RIKEN
Accelerator
Progress Reportvol.

理化学研究所 仁科加速器科学研究センター

RIKEN Nishina Center for Accelerator-Based Science

53

RIKEN Accelerator Progress Report
vol.

53

理化学研究所 仁科加速器科学研究センター
RIKEN Nishina Center for Accelerator-Based Science
Wako, Saitama, 351-0198 JAPANRIKEN Accelerator Progress Report 2019 vol.53
This is an unabridged version of the 53rd volume of RIKEN Accelerator Progress Report(hereinafter referred to as APR), the official annual report of the Nishina Center for
Accelerator-Based Science.
A PDF version of APR can be downloaded from our website.
http://www.nishina.riken.jp/researcher/APR/index_e.html

Published by
RIKEN Nishina Center for Accelerator-Based Science
2-1 Hirosawa, Wako-shi, Saitama 351-0198 JAPANDirector of RIKEN Nishina Center for Acclerator-Based Science
Hideto En’yo
Editorial Board
H. Ueno (Editor-in Chief), J. Zenihiro, T. Isobe, Y. Ichikawa, A. Kohama, E. Hiyama, T. Matsuzaki, R. Seidle, T. Doi,
T. Tada, T. Tamagawa, K. Takahashi, Y. Higurashi, K. Ozeki, T. Sumikama, K. Morimoto, H. Sato, M. Watanabe, T. Ikeda,
I. Watanabe, H. Haba, T. Abe, K. Tanaka, Y. Watanabe, H. Nagahama, M. Wada, Y. Tsuburai, M. Yamamoto, E. Fujino
and I. Yoshida
Contact
Progress@ribf.riken.jp
All rights reserved. This report or any portion thereof may not be reproduced or used in any form, including photostatic
print or microfilm, without written permission from the Publisher.
Contents of the manuscripts are the authors' responsibility. The Editors are not liable for the content of the report.
RIKEN Nishina Center for Accelerator-Based Science, September 2019

PREFACE
The RIKEN Accelerator Progress Report is the annual report of all research activities conducted in RIKEN Nishina
Center for Accelerator-Based Science (RNC). This volume, No. 53, covers the activities conducted in theJapanese ﬁscal year of 2019 (April 2019 to March 2020).
First, March 31, 2020 was the last day for Hideto En’yo
as the Director. Hideto led the RNC for a long period,
since October 2009. On this occasion, all RNC members
wish to express their gratitude and thank him for his management over ten and half years. During this period, oneof the many excellent achievements of RNC was the discovery of Element 113, “Nihonium.” The year 2019 was
designated as the International Year of the Periodic Table(IYPT). Hideto served as a member of the IYPT-Japan
Committee and organized a session for the Closing Ceremony in December, Tokyo, to demonstrate the world-wide
eﬀorts in “Creation of superheavy elements,” with a focus
on period-7 elements including Nihonium. In April 2019,
David Morrison was appointed as the Deputy Director of

RIKEN Brookhaven Research Center.
The year 2019 was the ﬁrst year of the new Japanese era “Reiwa,” which started on May 1. In RNC, this new period
was celebrated with the results obtained from the ﬁrst spectroscopy of 78 Ni, which was published in Nature, issued
on the second day of Reiwa, May 2. Other selected achievements are compiled in “Highlights of the Year” in thisvolume, which showcase the multi-disciplinary activities of RNC in the ﬁeld of science, technology, and innovation.
It should be noted that these achievements were made not just by in-house researchers and engineers in RNC; forsome of these projects, RNC collaborated with users at the RI Beam Factory (RIBF) and RIKEN Muon Facility at
the Rutherford Appleton Laboratory.
Two excellent progresses were made in the RIBF facility. The ﬁrst progress is the record breaking beam intensities
achieved at the Super-conducting Ring Cyclotron (SRC); the maximum intensity achieved for 124 Xe was 173 pnA, andthat for 238 U was 94 pnA. The excellent beams at SRC make the fast-beam programs at BigRIPS more productive,
especially for the nuclear structure study in 100 Sn and its vicinity, and in neutron-rich nuclei produced via in-ﬂight
ﬁssion. The second progress is the intensity- and energy-upgrade of the linear accelerator RILAC, which was achievedby the recent installations of the 28-GHz ECR ion source as well as super-conducting radio-frequency cavities. The
ﬁrst beam with the upgraded RILAC “SRILAC” was successfully extracted at the very end of FY2019. At the sametime, a new gas-ﬁlled recoil separator “GARIS-III” was installed to be coupled with SRILAC. The combination of
SRILAC and GARIS-III strengthens the scientiﬁc programs focused on super-heavy elements.
Two advisory committees, Nishina Center Advisory Committee (NCAC) and RIKEN Advisory Committee (RAC),
were organized. NCAC evaluated the RNC management with respect to organization, research achievement, andplanning, and they suggested that the intensity upgrade of RIBF was the ﬁrst priority in the coming years to becompetitive with other facilities across the world. Based on the report of NCAC, RAC provided this advice to the
President of RIKEN.
Since the end of FY2019, the social situation in the world has changed dramatically because of the COVID-19
pandemic. According to the measures of governments, universities, and institutes, research activities have been
limited signiﬁcantly. Remote-work and web-meetings using computer-network technology are highly recommended
and useful for organizing discussions and collaboration works. However, the importance of face-to-face discussions
and collaborations for increasing creativity has been recognized. It is hoped that research networks and relationships
over the world will become more involved in future to overcome this diﬃcult situation by sharing ideas and wisdom.

Hiroyoshi Sakurai
Director
RIKEN Nishina Center for Accelerator-Based Science

CONTENTS

RIKEN Accel. Prog. Rep. 53

C O N T E N T S
PagePREFACE
Ⅰ. HIGHLIGHTS OF THE YEAR
Strong one-neutron emission from two-neutron unbound states in β decays of r-process nuclei 86, 87Ga························
R. Yokoyama et al.

1

Shell evolution towards 60Ca: First spectroscopy of 62Ti···············································································
M. L. Cortés et al.

2

78

3

Ni revealed as a doubly magic stronghold against nuclear deformation···························································
R. Taniuchi et al.

Inclusive cross sections for one- and multi-nucleon removal from Sn, Sb, and Te projectiles
beyond the N = 82 shell closure·····································································································
V. Vaquero
g-Factor of the 99Zr isomer: monopole evolution in the shape-coexisting region···················································
F. Boulay et al.
Study of quasielastic barrier distributions as a step towards the synthesis of superheavy elementswith hot fusion reactions·············································································································
T. Tanaka et al.

4
5

6

Location of the neutron dripline at fluorine and neon··················································································
D. S. Ahn et al.

7

Dineutron correlation and rotational excitations in neutron-rich Mg isotopes······················································
M. Yamagami

8

xF dependence of the transverse single spin asymmetry of very forward π0 production in 510 GeV p↑ + p collisions········M. H. Kim et al.

9Non-evaporable getter-based differential pumping system for SRILAC·····························································
H. Imao et al.

10

Calibration of the beam energy position monitor system for the RIKEN superconducting acceleration cavity················
T. Watanabe et al.

11Intermediate silicon tracker development for sPHENIX experiment at RHIC······················································
I. Nakagawa et al.

12

Update of MOCO for the MPV system···································································································
H. Baba et al.

13

Offline measurement of mass and correlated decay properties using radioactive 224Ra source
via MRTOF+α-TOF detector········································································································
T. Niwase

14

Oﬄine collinear laser spectroscopy of barium II toward measurement of RIs at SLOWRI facility·····························
M. Tajima et al.

15

Angle-tunable wedge degrader for an energy-degrading RI beamline·······························································
J. W. Hwang et al.

16

Eﬀects of columnar defects introduced by 2.6 GeV U-ion irradiation on Jc characteristics of 2H-NbSe2·······················
T. Tamegai et al.

17

Impurity eﬀects on magnetism of T-type La1−x/2Eu1−x/2SrxCuO4······································································
M. Fujita

18

Size-dependent magnetic behavior of La2CuO4 nanoparticles·········································································
S. Winarsih et al.

19

Targeted alpha therapy of thyroid cancer: Evaluation of [211At]NaAt treatment in the xenograft model························
T. Watabe et al.

20

Live mouse imaging with 44mSc by a multiple-isotope PET············································································
T. Fukuchi et al.

21

Production cross sections of ytterbium and thulium radioisotopes in alpha-induced nuclear reactions on natural erbium····M. Saito et al.

22

RIKEN Accel. Prog. Rep. 53

CONTENTS

Production cross sections of dysprosium-159 radioisotope from the deuteron-induced reactions
on terbium-159 up to 24 MeV·······································································································
D. Ichinkhorloo et al.

23

Non-homologous end joining is the major repair pathway for DNA double strand breaks in human fibroblast
after heavy-ion irradiation···········································································································
M. Izumi and T. Abe

24

Mutation analysis pipeline V2: an improved version of bioinformatics pipeline for plantand microbial sequencing analysis··································································································
H. Ichida and T. Abe

25

Ⅱ. RESEARCH ACTIVITIES I (Nuclear, Particle and Astro-Physics)

1. Nuclear Physics
Decay studies in the region of 54Zn········································································································
A. Kubiela et al.

27

Study of the β-decay of 70Kr················································································································
A. Vitéz-Sveiczer et al.

28

Progress on the decay spectroscopy and measurement of half-lives and Pn values in exotic nuclei
near the N = 50 shell closure········································································································
C. J. Griffin et al.

29

Total absorption gamma spectroscopy studies around 100Sn···········································································
A. Algora et al.

30

New and comprehensive β- and βp-decay spectroscopy results in the vicinity of 100Sn···········································
J. Park et al.

31

Improved value for the Gamow-Teller strength of the 100Sn beta-decay·····························································
T. Faestermann and D. Lubos

32

β-delayed neutron emission probabilities for understanding the formationof the r-process rare-earth abundance peak (REP)···············································································
G. G. Kiss

33

Evolution of collectivity and mirror symmetry along N = Z···········································································
K. Wimmer

34

First attempt at in-beam γ-ray spectroscopy of 100Sn····················································································
S. Chen et al.

35

Intermediate-energy Coulomb excitation of 102Sn·······················································································
M. L. Cortés et al.

36

In-beam γ-ray spectroscopy of 136Te at relativistic energies············································································
V. Vaquero

37

Study of Gamow-Teller transitions from 11Li····························································································
L. Stuhl et al.

38

Structure of 13Be probed via quasi-free scattering·······················································································
Anna Corsi

39

Overview of the experimental setup of SAMURAI11 to measure the 48Cr(p, n) and 64Ge(p, n) reactionsin inverse kinematics·················································································································
M. Sasano et al.

40

Role of 66Se in the rp-process nucleosynthesis in type I X-ray bursts································································
V. Panin et al.

41

Particle identiﬁcation of light charged particle by SπRIT-TPC in Sn-Sn isotopic reactions II····································
Masanori Kaneko et al.

42Monte carlo simulation of collective ﬂow analysis for SπRIT-TPC··································································
M. Kurata-Nishimura et al.

43

Measurement of the proton elastic scattering from 132Sn at 300 MeV/nucleon·····················································
J. Zenihiro et al.

44

TDPAD measurement for the 10− isomer of 98Y·························································································J. M. Daugas et al.

45

Investigations of magnetic moments and spin alignment in Coulomb ﬁssion reaction············································
R. Lozeva et al.

46

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RIKEN Accel. Prog. Rep. 53

Magnetic-moment measurement of the isomeric state of 130Sn in the vicinity of the doubly—magic nucleus 132Sn···········
G. Georgiev, Y. Ichikawa et al.

47

Isomeric-to-ground state ratio of 128Sn measured by Rare RI Ring···································································
H. F. Li et al.

48

Performance study of electron spectrometer for SCRIT experiments································································
K. Tsukada et al.

49

Correlated measurement of mass and decay of fusion evaporation products for 51V+159Tb reactions
via MRTOF+α-TOF detector········································································································
T. Niwase et al.

50

Half-life determination of nuclear excited states of 229Th by the coincidence measurement between α particles
and γ rays from 233U···················································································································
Y. Shigekawa et al.

51

Mass measurements of 252Cf ﬁssion fragments via MRTOF-MS······································································
S. Kimura et al.

52

In-gas-cell laser ionization spectroscopy of Os isotopes using MRTOF-MS at KISS·············································
Y. Hirayama et al.

53

Calibration and simulation of LaBr3:Ce scintillator for analyzing 8Li(α, n)11B-reaction data·····································
Y. Mizoi et al.

54

Measurement of 25Al+p resonant elastic scattering relevant to the astrophysical reaction 22Mg(α, p)25Al······················
J. Hu et al.

55

26

Si beam production and thermal durability test of gas target window······························································
M. J. Kim et al.

56

Production of a high-intensity francium ion beam for the measurement of the electron electric dipole moment··············
H. Nagahama et al.

57

Development of β-NMR with spin-aligned beam·······················································································
H. Nishiabta et al.

58

Production of isomers around 52Fe nucleus via projectile fragmentation····························································
K. Kawata et al.

59

79

60

Se(n, γ)80Se reaction cross section through 77, 79Se(d, p)78, 80Se reactions···························································
N. Imai et al.

Production-cross-section measurement and new-isotope search for very neutron-deﬁcient RIs produced
from 78Kr beam at 345 MeV/nucleon by BigRIPS separator····································································
H. Suzuki et al.

61

Database of radioactive isotope beams produced at the BigRIPS separator·························································
Y. Shimizu et al.

62

RI beam production at BigRIPS in 2019·································································································
Y. Shimizu et al.

63

First success of RI-beam separation and particle identiﬁcation for nuclei with atomic number Z>82
at RIKEN RI beam factory··········································································································
T. Sumikama et al.
Analysis of fake asymmetry for the MTV experiment·················································································
F. Goto et al.

65
66

2. Nuclear Physics (Theory)
Non-relativistic expansion of Dirac equation with spherical vector and scalar potentials·········································Y. X. Guo and H. Z. Liang

67

Renormalizing random-phase approximation by using exact pairing································································
L. Tan Phuc et al.

68

Quenching factor of Gamow-Teller and spin dipole resonances······································································
Li-Gang Cao, H. Sagawa et al.

69

Pairing in excited nuclei: a review········································································································
N. Quang Hung et al.

70

Canonical base in self-consistent constrained HFB in odd-A nuclei·································································
K. Sugawara-Tanabe and K. Tanabe

71

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CONTENTS

S-shaped heat capacity in an odd-odd deformed nucleus··············································································
B. Dey et al.

72

Evidence for three-particle correlations in nuclear matter·············································································
W. Bentz and I.C. Cloet

73

Double charge-exchange phonon states··································································································
X. Roca-Maza, H. Sagawa et al.

74

3. Nuclear Data
EXFOR compilation of RIBF data in 2019······························································································
T. Tada75

4. Hadron Physics
Unfolding the transverse momentum distribution for very forward neutron production in pAu collisions—at √ sNN = 200 GeV···················································································································
B. Mulilo et al.
–77

Update of single and dihadron cross sections for light hadrons in e+e− annihilation at √ s = 10.58 GeV in Belle·············
Ralf Seidl

78

Preparation status of the J-PARC E16 experiment in 2019············································································
S. Yokkaichi

79

Measurement of nuclear eﬀects on anti-quarks via Drell-Yan process at FNAL-SeaQuest·······································
K. Nakano et al.

80

Progress of the polarized Drell-Yan experiment at Fermilab, SpinQuest (E1039)··················································
Y. Miyachi et al.

81

Development of zero-degree calorimeter for EIC·······················································································
Y. Goto et al.

82

INTT Silicon Modules and Ladders Assembly for sPHENIX Project································································
C. Miraval et al.

83

6. Particle Physics
Empirical formulas for the standard-model parameters················································································
Y. Akiba

85

Quarternion-spin-isospin model for the standard-model parameters·································································
Y. Akiba

86

R = 12H02 and its implications to gravity and cosmology··············································································
Y. Akiba

87

7. Astrophysics and Astro-Glaciology
Experimental equipment for exploring reactions of low energy ions with an ice surface as an interstellar dust analog······
Y. Nakai et al.
Commissioning of a prototype novel laser melting sampler for analyzing ice cores with high depth resolution
and high throughput··················································································································
Y. Motizuki et al.

89

90

8. Accelerator
Revaluation of beam orbit calculation method for the injection line of AVF cyclotron
after tuning pepper-pot emittance monitor·························································································
Y. Kotaka et al.

91

Non-thermal equilibrium eﬀect on plasma window with large diameter····························································
N. Ikoma et al.

92

Status report on update of alarm system and control system of magnet power supplies for RIBF·······························
M. Komiyama et al.

93

Power supply backup system for injection and extraction magnets of cyclotrons··················································
K. Kumagai and N. Fukunishi

94

Improvement of beam stability by stabilizing the cooling-water temperature for the main and trim coils of IRC·············
R. Koyama et al.

95

Interlock signal application from radiation monitoring ion chamber for SRC······················································
M. Nakamura et al.

96

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Nishina RIBF water-cooling system operational report 2019·········································································
T. Maie et al.

97

9. Instrumentation
Development of ZeroDegree Large Acceptance Dispersive mode····································································
H. Takeda et al.

99

Large-acceptance achromatic mode with mono-energetic wedge degrader for ZeroDegree spectrometer······················
S. Chen et al.

100

New ion-optical operating modes of BigRIPS and ZeroDegree spectrometer for production and separationof high-quality rare isotope beams and high-resolution spectrometer experiments··········································
H. Takeda et al.

101

Puriﬁcation of slowed-down RI beam····································································································
T. Sumikama et al.

102

Thermal model simulation of high-power rotating target for BigRIPS separator···················································
K. Yoshida et al.

103

Incidents involving the DMT3 magnet in the beam transport line from SRC to BigRIPS········································
K. Kusaka et al.

104

First conﬁrmation of stopped RIs at parasitic gas cell with new approach··························································
T. Sonoda et al.

105

Stopping examination for high-energy RI beams in the parasitic gas cell···························································
T. Sonoda et al.

106

Second report on oﬄine tests for RF carpet transportation in RF ion guide gas cell at the SLOWRI facility··················
S. Iimura et al.

107

The 3rd report on oﬄine test for RF carpet transportation in RF ion guide gas cell at the SLOWRI facility···················
A. Takamine et al.

108

Battery-operated compact ion source for beam transport test·········································································T. M. Kojima et al.

109

Present status of ERIS at the SCRIT electron scattering facility······································································
T. Ohnishi et al.

110

Latest performance of FRAC at SCRIT facility·························································································
S. Sato et al.

111

3D magnetic ﬁeld measurement of the SCRIT electron spectrometer································································
H. Wauke et al.

112

Measurement of the luminosity of electron scaterring at SCRIT·····································································
D. Taki et al.

113

Yield development with in-gas-jet laser ionization at KISS···········································································Y. X. Watanabe et al.

114

Observation of charge-stripping of 20 keV/q ions upon injection into gas cell cooler-buncher at KISS························
P. Schury et al.

115

Reliable connection methods for gas piping and signal cabling of PPAC in focal-plane vacuum chambers at BigRIPS·····
H. Sato et al.

116

Performance of a none-isochronous position-sensitive detector for the Rare-RI Ring·············································
R. Crane and S. Naimi

117

Intermediate Tracker Integration in sPHENIX··························································································
R. Nouicer, I. Nakagawa et al.

118

Assembly of Intermediate Silicon Tracker in Taiwan···················································································
C. Shih et al.

119

Development status of long data cable for sPHENIX-INTT detector································································
T. Hachiya et al.

120

Performance evaluation of a sensor module for INTT at sPHENIX··································································
A. Suzuki et al.

121

Sensor testing of Intermediate Silicon Tracker··························································································
K. Cheng et al.

122

Geant4 simulation of INTT Phase-2 Test Beam at Fermilab··········································································
C. Shih et al.

123

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Development of high-resolution hard X-ray detector system by using transition-edge sensor
for accelator-based experiments·····································································································
T. Isobe et al.

124

SAMURAI DAQ speed improvement····································································································
J. GAO et al.

125

High-stability high-voltage power supply for MRTOF·················································································
P. Schury et al.

126

Eliminating mass-dependent inaccuracies in MRTOF-MS for the study of RI using arbitrary reference masses··············
M. Rosenbusch

127

On-line mass measurement using multi-reﬂection time-of-ﬂight mass spectrograph (MRTOF-MS) at KISS··················J. Y. Moon et al.

128

Collinear laser spectroscopy of Ba+ in 6s 2S1/2-6p 2P3/2 transition·····································································
Y. Sasaki et al.

129

LIF observation of Rb atoms in superﬂuid helium by picosecond pulsed laser pumping·········································Y. Takeuchi et al.

130

Measurement of stopping-position width of highly energetic Rb ion beams in liquid nitrogen··································
M. Nishimura et al.

131

Investigation of the secondary rubidium beam proﬁle at HIMAC towards laser spectroscopy in an optical cryostat·········
K. Tsubura et al.

132

Degrader system for ZD-MRTOF·········································································································J. J. Liu et al.

133

First test of graphenic carbon vacuum windows with heavy ions·····································································
S. Purushothaman et al.

134

Heavy-ion irradiation test of radiochromic ﬁlms························································································
T. Kambara et al.

135

Computing and network environment at the RIKEN Nishina Center································································
T. Ichihara136

CCJ operations in 2019·····················································································································
S. Yokkaichi et al.

137

Ⅲ. RESEARCH ACTIVITIES II (Material Science and Biology)

1. Atomic and Solid State Physics (Ion)
Control of electrical conductivity in diamond by boron implantation—application of high-temperatureand high-pressure annealing·········································································································
H. Yamazaki et al.

139

Superconducting proximity eﬀect in epitaxial Nb(110)/Au(111)/Nb(110) trilayers················································
H. Yamazaki et al.

140

Simultaneous cluster dissociation and optical pumping of Ag in superﬂuid helium using a single UV laser···················
T. Yamamoto et al.

141

Baseline correction system for precision measurement of the hyperﬁne structure of Rb atoms in superﬂuid helium·········
M. Doi et al.

142

Proﬁle measurement of laser microbeam produced by glass capillaries: tilt dependence·········································
M. Mori et al.

143

2. Atomic and Solid State Physics (Muon)
Study on magnetism of defective reduced graphene oxides···········································································
R. Asih et al.

145

Magnetic ground state of Jeﬀ = 0 Mott insulator Ag3LiRu2O6 under pressure·······················································
T. Takayama et al.

146

Non-magnetic ground state of In2Ru2O7 probed by muon spin rotation······························································
T. Takayama et al.

147

Short-range magnetic order in the frustrated antiferromagnet Cu5(PO4)3(OH)4 (pseudomalachite)······························
H. Kikuchi et al.

148µSR investigation of spin liquid states in magnetic properties of MgTi2O4 sample················································
U. Widyaiswari et al.

149

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Zero-point vibrational energy in the muon sites of La2CuO4··········································································
M. R. Ramadhan et al.

150

Investigations of the quantum critical behavior of the S =1/2 J1-J2 square lattice antiferromagnets Sr2Cu(Te1−xWx)O6·······
Sungwon Yoon et al.

151

Magnetic ordering and spin dynamics of Nd2Ru2O7 studied by µSR·································································
U. Widyaiswari et al.

152

Muon spin relaxation study of solute-vacancy interactions during natural aging of Al–Mg–Si–Cu alloys·····················
K. Nishimura et al.

153

Muon spin rotation study on the new organic spin liquid candidate λ-(STF)2GaCl4···············································
T. Minamidate et al.

154

Zero-ﬁeld µSR on single-crystal organic superconductor λ-(BETS)2GaCl4·························································
D. P. Sari et al.

155

Relationship between the structure and electrical conductivity of 12-mer single-stranded polyadenine studied
by scanning tunneling microscope··································································································
H. Rozak et al.

156

Electron transfer in 12-mer double-stranded DNA by muon spectroscopy and scanning tunneling microscopy···············
H. Rozak et al.

157µSR study of the electron transfer mechanism of a blue copper protein, Pseudoazurin···········································
A. D. Pant et al.

158

Temperature dependence of the total muonium emission yield from silica aerogel using µSR method·························
K. Ishida et al.

159

3. Radiochemistry and Nuclear Chemistry
Relativistic density functional theory with the ﬁnite-light-speed correction for Coulomb interaction···························
T. Naito and R. Akashi et al.

161

On-line anion-exchange experiment of Nb and Ta in HF/HNO3 mixture solution for Db chemistry····························
S. Adachi et al.

162

Anion-exchange behaviour of Nb, Ta and Pa in H2SO4················································································
M. Kato et al.

163

Anion exchange of Nb and Ta in HF/HCl mixture solution for Db chemistry······················································
T. Yokokita and H. Haba

164

Anion exchange of element 104, Rf, at 0.11 M H2SO4 by using batch-type solid-liquid extraction apparatus, AMBER·····
T. Yokokita et al.

165

Anion exchange of Zr, Hf, and Th by the automated extraction apparatus: toward the chemical study of 104Rf in HNO3····
E. Watanabe et al.

166

99

Ru and 57Fe Mössbauer spectroscopic studies of Na2Ru1−xFexO3 of sodium-ion battery electrode······························
H. Hamano et al.

167

Development of an RF-carpet gas cell for the chemistry of superheavy elements·················································
Y. Shigekawa et al.

168

An attempt to modify the membrane degasser (MDG)·················································································
Y. Komori et al.

169

Preparation of Gd targets for in-beam ﬁssion measurements as a step towards the handling of 243Am targets
with ultra-thin backings··············································································································
T. Tanaka et al.

170

Preparation of [211At]-labeled sodium astatide (NaAt) by reducing with ascorbic acid for the treatmentof thyroid cancer······················································································································
Y. Shirakami

171

Development of radioimmunotherapy with astatine-211-counjugated antibodies··················································
H. Takashima et al.

172

Anti-cancer eﬀect of 211At-labeled antibody on xenografted mice with intravenous injection····································
Y. Kanayama et al.

173

Dispersion rates of astatine-211 from aqueous solutions and chloroform···························································
A. Toyoshima et al.

174

Usability of 67Cu as a therapeutic radioisotope for peptide receptor radionuclide therapy········································
Y. Fujisawa et al.

175

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Quality evaluation of RIKEN 67Cu for labeling peptide compound··································································S. Oshikiri et al.

176

Simultaneous imaging of Na+/K+ by semiconductor Compton camera GREI·······················································S. Motomura et al.

177

Research progress on double-photon-emission coincidence imaging with cascade gamma-ray-emitting nuclide·············
M. Uenomachi et al.

178

Production of Np-236 in the 232Th + 7Li reaction for standard material in accelerator mass spectrometry······················
Y. Hayakawa et al.

179

Excitation function measurement of the Tl(d, α)203Hg reaction for carrier-free 203Hg tracer production························Y. Takahashi et al.

180

Activation cross sections of alpha-induced reactions on natural tungsten for 186Re and 188Re production·······················
N. Ukon et al.

181

Activation cross sections of alpha particle-induced reactions on natural hafnium up to 50 MeV································S. Takacs et al.

182

Activation cross sections of alpha-induced reactions on natural ytterbium up to 50 MeV········································
M. Saito et al.

183

Measurement of excitation functions for 165Ho(α, xn)165–168Tm reactions····························································
A. R. Usman et al.

184

Production cross sections of (d, x) reactions on natural erbium·······································································
M. U. Khandaker et al.

185

Activation-cross-section measurement of alpha-induced reactions on natural dysprosium·······································
T. Murata et al.

186

Production cross sections of 157Dy in alpha-particle-induced reactions on natural gadolinium···································
D. Ichinkhorloo et al.

187

Activation cross sections of alpha-particle induced nuclear reactions on natural palladium······································
M. Aikawa et al.

188

Excitation function measurement for zirconium-89 and niobium-90 production using alpha-induced reactions
on yttrium-89··························································································································
T. Murata et al.

189

Production cross sections of 68Ga via deuteron-induced reactions on natural zinc·················································
Ts. Zolbadral et al.

190

Production cross sections of 45Ti via deuteron-induced reaction on 45Sc·····························································
Ts. Zolbadral et al.

191

Present status of 211At production at the RIKEN AVF cyclotron······································································
Y. Wang et al.

192

Decontamination of Po in the 211Rn/211At generator system············································································
K. Aoi et al.

193

Separation and puriﬁcation of 139Ce tracer for metallofullerene synthesis···························································
K. Akiyama et al.

194

Separation of 121mTe from antimony without redox reaction···········································································
T. Kubota et al.

195

Chemical separation of theranostic radionuclide 111Ag produced in natPd(d, x)111Ag reactions····································
K. Ooe et al.

196

Preliminary investigation of nanoclay-gel-based ﬂuorescent gel dosimeters under carbon-ion beam···························
T. Maeyama et al.

197

4. Radiation Chemistry and Biology
Mutants of the ectomycorrhizal mushroom Tricholoma matsutake that exert detrimental eﬀects
on its symbiotic partner Pinus densiﬂora··························································································
H. Murata et al.

199

Eﬀect of heavy-ion-beam irradiation on mycelial growth of medicinal mushrooms···············································
M. Hatashita, K. Takagi et al.

200

Yield improvement of starch-degrading enzyme in fungi by ion-beam mutagenesis··············································
H. Iwahara et al.

201

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RIKEN Accel. Prog. Rep. 53

Mutation breeding of sake yeast using heavy-ion-beam irradiation··································································
K. Baisho et al.

202

Isolation of morphological mutants in a bryophyte model Marchantia polymorpha using heavy-ion mutagenesis···········
S. Sakai et al.

203

Breeding of summer-autumn-ﬂowering small-ﬂowered spray-type chrysanthemums cultivar ‘Nagasaki SWC1’
by heavy-ion-beam irradiation······································································································
A. Hisamura et al.

204

Mutation induction in strawberry of original Saitama cultivar by C-ion irradiation···············································
H. Uchida et al.

205

Characteristics of heavy-ion mutagenesis in cultivated strawberry···································································
T. Wada et al.

206

Improvement of the Brix content of the sweet potato “Anno-Beni” by mutation induced
using heavy-ion-beam irradiation···································································································
T. Hashiguchi et al.

207

Development of mutagenesis technique for leguminous crops using heavy-ion-beam irradiationand screening of useful mutants·····································································································
P. Siviengkhek et al.

208

Mutants of sorghum variety “WRAY” induced by heavy-ion irradiation····························································
H. Cai et al.

209

Genetic analysis of an early ﬂowering rice mutant induced by argon ions··························································
R. Morita et al.

210

Approach toward isolating early-heading mutants from Tana Toraja local aromatic rice “Pare Bau” irradiatedwith argon- and carbon-ion beams··································································································A. M. Okasa et al.

211

A novel domain of LONG GRAIN 1 in rice possesses transcriptional activation activity·········································
H. Abe et al.

212

Establishment of large mutant lines on rotifer using heavy-ion-beam irradiation··················································
K. Tsunezumi et al.

213

Contribution of multiple DNA repair pathways in Arabidopsis thaliana dry seeds after heavy-ion-beam irradiation········
K. Ishii et al.

214

Ion-microbeam irradiation to damage DNA in RPE cell nucleus with tapered glass capillary optics at Pelletron facility····T. Ikeda et al.

215

Ⅳ. OPERATION RECORDS
Electric power consumption of RIKEN Nishina Center in 2019······································································
E. Ikezawa et al.

217

Operation report of the ring cyclotrons in the RIBF accelerator complex···························································
N. Tsukiori et al.

218

RILAC operation····························································································································
E. Ikezawa et al.

219

Operation report on the RIKEN AVF cyclotron for 2019··············································································
M. Hamanaka et al.

220

Present status of the liquid-helium supply and recovery system······································································
T. Dantsuka et al.

221

Operation of the BigRIPS cryogenic plant·······························································································
K. Kusaka et al.

222

Radiation safety management at RIBF···································································································
K. Tanaka et al.

223

Operation of the Pelletron tandem accelerator···························································································
T. Ikeda et al.

225

Fee-based activities operated by the Industrial Application Research Team························································
A. Yoshida et al.

226

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CONTENTS

Ⅴ. EVENTS
Nishina School 2019························································································································
H. Ishiyama et al.

227

Creation of superheavy elements highlighted at the closing ceremony of IYPT 2019·············································
H. Enʼyo228

The 3rd “Hodan-kai” meeting for the future of exotic nuclear physics······························································
W. Horiuchi et al.

229

SHE2019—The 4th International Symposium on Superheavy Elements····························································
H. Haba230

RIKEN Symposium “Trends in ion-beam breeding over the last two decades and future research”····························
T. Abe et al.

231

RIKEN Open Day 2019·····················································································································
H. Haba and K. Takahashi

232

Outreach activities outside the Wako campus···························································································
N. Miyauchi

233

Ⅵ. ORGANIZATION AND ACTIVITIES OF RIKEN NISHINA CENTER(Activities, Members, Publications & Presentations)
1. Organization ······························································································································

235

2. Finances ···································································································································

236

3. Staffing ····································································································································

236

4. Research publication ····················································································································

237

5. Management ······························································································································

238

6. International Collaboration ·············································································································

241

7. Awards ·····································································································································

243

8. Brief overview of the RI Beam Factory ·······························································································

245

Nuclear Science and Transmutation Research Division
Radioactive Isotope Physics Laboratory ··························································································

247

Spin isospin Laboratory ·············································································································

257

Nuclear Spectroscopy Laboratory ··································································································

264

High Energy Astrophysics Laboratory ····························································································

270

Superheavy Element Research Group ·····························································································

274

Superheavy Element Production Team ·····················································································

276

Superheavy Element Device Development Team ·········································································

281

Astro-Glaciology Research Group ·································································································

283

Nuclear Transmutation Data Research Group ····················································································

286

Fast RI Data Team ·············································································································

287

Slow RI Data Team ············································································································

289

Muon Data Team ···············································································································

290

High-Intensity Accelerator R&D Group ··························································································

292

High-Gradient Cavity R&D Team ···························································································

293

High-Power Target R&D Team ······························································································

294

Research Facility Development Division
Accelerator Group ····················································································································

295

Accelerator R&D Team ·······································································································

297

Ion Source Team ···············································································································

299

RILAC Team ···················································································································

300

CONTENTS

RIKEN Accel. Prog. Rep. 53

Cyclotron Team ················································································································

301

Beam Dynamics & Diagnostics Team ······················································································

303

Cryogenic Technology Team ·································································································305

Infrastructure Management Team ···························································································

306

Instrumentation Development Group ······························································································308

SLOWRI Team ·················································································································

310

Rare RI-ring Team ·············································································································

314

SCRIT Team ····················································································································

317

Research Instruments Group ········································································································

320

BigRIPS Team ·················································································································321

SAMURAI Team···············································································································

326

Computing and Network Team ······························································································

330

Detector Team ··················································································································

332

Accelerator Applications Research Division
Beam Mutagenesis Group ···········································································································

335

Ion Beam Breeding Team ·····································································································

336

Plant Genome Evolution Research Team ···················································································340

RI Application Research Group ····································································································

342

Nuclear Chemistry Research Team ··························································································

343

Industrial Application Research Team ······················································································

352

Subnuclear System Research Division
Quantum Hadron Physics Laboratory ·····························································································

354

Strangeness Nuclear Physics Laboratory ·························································································

358

Radiation Laboratory ················································································································

361

Meson Science Laboratory ··········································································································366

RIKEN BNL Research Center ······································································································

371

Theory Group ··················································································································

372

Experimental Group ···········································································································

377

Computing Group ··············································································································382

RIKEN Facility Office at RAL ·····································································································

387

Safety Management Group ················································································································

391

User Liaison Group ·························································································································

393

RIBF User Liaison Team ············································································································

394

Outreach Team ························································································································

395

Office of the Center Director ··············································································································

396

Partner Institutions ··························································································································

399

Center for Nuclear Study, Graduate School of Science, The University of Tokyo ··········································

400

Wako Nuclear Science Center, IPNS (Institute of Particle and Nuclear Studies),
KEK (High Energy Accelerator Research Organization) ································································

413

Events (April 2019 — March 2020) ······································································································

417

Press Releases (April 2019−March 2020) ·······························································································

418

Ⅶ. LIST OF PREPRINTS
List of Preprints (April 2019―March 2020) ····························································································

419

RIKEN Accel. Prog. Rep. 53

CONTENTS

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS
List of Symposia & Workshops (April 2019―March 2020) ··········································································

421

List of Seminars (April 2019―March 2020) ···························································································

421

I. HIGHLIGHTS OF THE YEAR<< Selection process of highlights >>Highlights are selected by a two-step process. In the first step, a referee who reviews a manuscript decides
whether she/he would recommend it as one of the highlights.
Members of the editorial board then make additional recommendations if they think an important contribution
has not been recommended by the referee.
The second step involves the editor-in-chief proposing a list of highlights based on the recommendation given
above to the editorial board. After discussing the scientific merits and uniqueness of the manuscripts fromviewpoints of experts/non-experts, the editorial board makes the final decision.

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Strong one-neutron emission from two-neutron unbound states inβ decays of r -process nuclei 86, 87 Ga†

Delayed neutron emission after β decays is found inneutron-rich nuclei in which the energy window of β −decay (Qβ ) is high enough to populate excited statesof the daughter nucleus above the neutron separationenergy (Sn ). All of the neutron-rich nuclei on the rprocess path are either one or multi-n β-delayed precursors. Delayed neutron emission shapes the ﬁnal
abundance pattern owing to the modiﬁcation of theisotopic population through the modiﬁcation of the decay path back to stability and by contributing significantly to the neutron ﬂux after freeze-out. However,experimental data that enable the evaluation of therole of multi-n emission for the r-process nuclei arealmost non-existent. Often, predictions for neutron
emission probabilities are based on a simpliﬁed cut-oﬀ
model that neglects γ-decay competition and assumes
that only the higher-multiplicity neutron emission prevails in the energy regions open to multiple neutronemission channels.
We studied neutron-rich Ga isotopes by means of
β-neutron-γ spectroscopy at RIBF using the in-ﬂight
ﬁssion of a 345 MeV/nucleon 238 U86+ beam on a 4mm-thick 9 Be production target. For decay measurement, 7 × 104 and 6 × 103 ions of 86 Ga and87
Ga, respectively, were transported to the ﬁnal focal
plane. Double-sided silicon-strip detectors (DSSSDs),
AIDA,1) WAS3ABi,2) and a YSO scintillator3) were
employed for ion and β correlation measurements. The
3
He neutron counter array, BRIKEN,4) was used forneutron measurement.
The half-lives and Pxn values were obtained throughthe analysis described in Ref. 6). The P1n and P2nvalues obtained in this work for 86 Ga are consistent
with the data reported by Miernik et al.7) We discovered new β-delayed two-neutron emitters, 84, 85, 87 Ga,
and measured their two-neutron branching ratio forthe ﬁrst time. Figure 1 shows a comparison of the experimental neutron branching ratio with shell-model
calculations based on the cut-oﬀ model reported by
Madurga et al.5) and shell-model calculations based on
the Hauser-Feshbach statistical model.8) When comparing the new experimental results with the predictions from the shell-model calculations, we notice a
discrepancy between the cut-oﬀ model and experimental data for all investigated β2n gallium precursors,
†

∗1
∗2
∗3
∗4
∗5

Neutron branching ratio (%)

R. Yokoyama,∗1 R. Grzywacz,∗1,∗2 B. C. Rasco,∗1,∗2 N. T. Brewer,∗1,∗2 K. P. Rykaczewski,∗2 I. Dillmann,∗3
J. L. Tain,∗4 and S. Nishimura∗5 for the BRIKEN collaboration
100
P1n GT (cutoff)
P1n GT+FF (cutoff)
P1n GT+FF (stat.)
P1n EXP50

P2n GT (cutoff)
P2n GT+FF (cutoff)
P2n GT+FF (stat.)
P2n EXP

0

51

52

53

54

55
56
Neutron number N

Fig. 1. Comparison of the experimental data and the predictions from the shell-model calculations by Madurga
et al.5) “GT” and “GT+FF” in the legend denote shellmodel calculations with pure Gamow-Teller and GT +ﬁrst forbidden transitions, respectively. The GT+FF
predictions, when coupled with the statistical model(stat.), provide a much better agreement with the data
than the cutoﬀ model.

which is most dramatically manifested in 87 Ga.
In contrast to the cut-oﬀ model, the inclusion of
the statistical model correctly reproduces the dominating role of one-neutron emission from two-neutron
unbound states. This result is the ﬁrst clear case inmedium/heavy nuclei where the eﬀects of statisticalemission must be considered to model β-delayed multineutron emission, which is of particular importance for
r-process modeling. The strong 1n emission from 2n
unbound states will require more detailed studies ofneutron and γ-ray spectra to establish the details of
the emission process. The detection of neutron energies and γ-ray energies is required to better constrain
both the strength-distribution models and statisticalmodel parameters.
References

1) C. J. Griﬃn et al., PoS NIC XIII, 097 (2014).
2) S. Nishimura et al., RIKEN Accel. Prog. Rep. 46, 182(2013).
3) R. Yokoyama et al., Nucl. Instrum. Methods Phys. Res.
A 937, 93–97 (2019).
4) A. Tarifeño-Saldivia et al., J. Instrum. 12, P04006(2017).
5) M. Madurga et al., Phys. Rev. Lett. 117, 092502 (2016).
6) B. C. Rasco et al., Nucl. Instrum. Methods Phys. Res.
A 911, 79 (2018).
7) K. Miernik et al., Phys. Rev. Lett. 111, 132502 (2013).
8) T. Kawano et al., Nucl. Phys. A 913, 51 (2013).

Condensed from article Phys. Rev. C 100, 031302(R)University of Tennessee, Knoxville
Oak Ridge National Laboratory
TRIUMF
IFIC (CSIC, Universitat de Valencia)
RIKEN Nishina Center-1-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Shell evolution towards 60 Ca: First spectroscopy of 62 Ti†
M. L. Cortés,∗1,∗2 W. Rodriguez,∗1,∗3 P. Doornenbal,∗1 A. Obertelli,∗4,∗5 J. D. Holt,∗6 S. M. Lenzi,∗7
J. Menéndez,∗8 F. Nowacki,∗9 K. Ogata,∗10,∗11 A. Poves,∗12 T. R. Rodríguez,∗12 A. Schwenk,∗5,∗13,∗14
J. Simonis,∗15 S. R. Stroberg,∗6,∗16 and K. Yoshida∗17 for the SEASTAR2017 collaboration.
4

Energy (MeV)

The study of N = 40 isotones can provide insight
into the mechanisms governing shell evolution. Alongthis isotonic chain diﬀerent behaviors are observed: 68 Ni
1)
For Fe and Cr,
shows a high E(2+1 ) and a low B(E2)↓.
+
a monotonous decrease of the E(21 ) when approaching N = 40 has been observed,1) while the E(2+1 ) of58, 60
Ti shows a moderate decrease towards N = 40.2,3)
The very exotic 60 Ca, where the Ca isotopic chain meets
the N = 40 isotones, is diﬃcult to reach experimentallyand only recently its existence has been established.4)
Theoretical calculations in the shell-model framework5)
concluded that quadrupole correlations in the N = 40
isotopes give rise to deformed ground states dominatedby intruder neutron orbits beyond the pf shell, leading
to an island of inversion below 68 Ni. On the other hand,symmetry conserving conﬁguration mixing calculations
with the Gogny interaction predict a conservation of theN = 40 gap leading to spherical 62 Ti and 60 Ca.6) In thiswork, the ﬁrst spectroscopy of 62 Ti is presented.
A 345 MeV/nucleon beam of 70 Zn with an average intensity of 240 pnA was fragmented on a Be target to produce 63 V. The isotopes were identiﬁed using BigRIPS7)
and delivered to the 151.3(13) mm long liquid hydrogen target of MINOS8) placed in front of the SAMURAI
magnet. Outgoing 62 Ti fragments were identiﬁed using SAMURAI and associated detectors.9) MINOS was
surrounded by DALI2+ , composed of 226 NaI(Tl) detectors.10,11)
Two peaks were clearly identiﬁed in the Doppler corrected γ-spectrum, and were found to be in coincidence.
Using a 2-dimensional χ2 minimization the energies of
the transitions were deduced to be 683(10) keV and823(20) keV, which were tentatively assigned to the+++2+
1 → 0gs and 41 → 21 transitions, respectively. The+
evolution of measured E(2+1 ) and E(41 ) energies for theE(2 +1 ):3E(4 +1 ):LiteratureThis work
LSSM
SCCM
VS-IMSRG

LiteratureThis work
LSSM
SCCM
VS-IMSRG

2
E(4 +1 )1E(2 +1 )

N=40
0
20

22

24

26

28

30

32

Z
+
Fig. 1. Systematics of E(2+1 ) and E(41 ) for even-even N =40 isotones, including the present measurement. The
black, green, and purple lines represent LSSM, SCCM,
and VS-IMSRG calculations, respectively.

N = 40 isotones between Ti and Ge1) is presented in+
62
Fig. 1. The E(2+Ti have a similar
1 ) and E(41 ) of66
value than the ones measured for Fe, higher than thoseof 64 Cr. This shows the ﬁrst increase of E(2+1 ) along
the N = 40 isotones towards 60 Ca. Large Scale Shell
Model (LSSM) calculations using the LNPS interaction
reproduce very accurately the data, indicating that theisland of inversion in this region extends down to 60 Ca.
Symmetry conserving conﬁguration mixing (SCCM) calculations using the Gogny D1S eﬀective interaction pre64
Cr and 66 Fe which lie very close todict E(2+1 ) forthe LSSM predictions. However, for 62 Ti a larger in+crease of the E(2+1 ) is obtained. For the E(41 ) energies,
the calculations overestimate the experimental values by
about 500 keV, although the minimum value for 64 Cr
is maintained. Ab initio valence-space in-medium similarity renormalization group (VS-IMSRG) calculations+
overestimate the E(2+1 ) and E(41 ) excitation energies in
62
64
66
Ti, Cr, and Fe, predicting all states as spherical.

Condensed from Phys. Lett. B 800, 135071 (2020)
RIKEN Nishina Center∗2 INFN-Laboratori Nazionali di Legnaro∗3 Universidad Nacional de Colombia∗4 IRFU, CEA, Université Paris-Saclay∗5 Institut für Kernphysik, Technische Universität Darmstadt∗6 TRIUMF∗7 Dipartimento di Fisica e Astronomia, Università di Padova∗8 Center for Nuclear Study, The University of Tokyo∗9 IPHC, CNRS/IN2P3, Université de Strasbourg∗10 RCNP, Osaka University∗11 Department of Physics, Osaka City University∗12 Departamento de Física Teórica, Universidad Autónoma de
Madrid
∗13 EMMI, GSI Helmholtzzentrum für Schwerionenforschung∗14 Max-Planck-Institut für Kernphysik∗15 Institut für Kernphysik, Johannes Gutenberg-Universität∗16 Department of Physics, University of Washington∗17 Advanced Science Research Center, Japan Atomic Energy
Agency†∗1

References

1) http://www.nndc.bnl.gov/ensdf/ .
2) H. Suzuki et al., Phys. Rev. C 88, 024326 (2013).
3) A. Gade et al., Phys. Rev. Lett. 112, 112503 (2014).
4) O. B. Tarasov et al., Phys. Rev. Lett. 121, 022501 (2018).
5) S. M. Lenzi et al., Phys. Rev. C 82, 054301 (2010).
6) T. R. Rodríguez et. al., Phys. Rev. C 93, 054316 (2016).
7) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, (2012).
8) A. Obertelli et al., Eur. Phys. J. A 50, (2014).
9) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
10) S. Takeuchi et al., Nucl. Instrum. Methods Phys. Res. A
763, 596 (2014).
11) I. Murray et al., RIKEN Accel. Prog. Rep. 51, 158 (2017).
-2-

Ⅰ. HIGHLIGHTS OF THE YEAR78

RIKEN Accel. Prog. Rep. 53

Ni revealed as a doubly magic stronghold against nuclear
deformation†

R. Taniuchi,∗1,∗2 C. Santamaria,∗3,∗2 P. Doornenbal,∗2 A. Obertelli,∗3,∗2,∗4 and K. Yoneda∗2
for SEASTAR2014 Collaboration

†

∗1
∗2
∗3
∗4

Counts / 80 keV

The doubly magic character of 78 Ni was investigated
for the ﬁrst time via the in-beam γ-ray spectroscopic
technique at the RIBF. Vital to the experiment wasa high intensity 238 U primary beam, accelerated by
the RIBF’s cyclotron complex and followed by the BigRIPS spectrometer1) for the production of the secondary cocktail beams. BigRIPS was centered on 79 Cu
and 80 Zn ions, which are bound by one and two protons
more than the target isotope 78 Ni. Excited states of78
Ni were populated by one- and two-proton knockout
reactions, respectively. To produce the excited statesin suﬃcient numbers, a new secondary target system,MINOS,2) was implemented. It consisted of a 10cm long liquid hydrogen target surrounded by a timeprojection chamber to trace outgoing protons following
the proton knockout reactions. Reaction residues were
tagged by the ZeroDegree spectrometer1) installed behind MINOS. De-excitation γ rays emitted in prompt
coincidence with the secondary reactions were detectedby the large volume γ-ray scintillator array DALI2.3)
The γ-ray spectra of the (p, 2p) and (p, 3p) reactions
are shown in Fig. 1. The energies of the peaks indicatedin the ﬁgure were deduced by maximum-likelihood ﬁts
with simulated response functions. As a result, a clear
high-energy γ-ray transition observed at 2,600(33) keV
in the (p, 2p) reaction illustrates the persistence of the
doubly magic nature of 78 Ni. However, another transition at a similar energy, 2,910(43) keV observed in the(p, 3p) channel, questions the stability of the protonand neutron shell closures.
The obtained levels of the excited states have been
compared with several state-of-the-art calculations.
Two large-scale shell-model calculations, LSSM and
MCSM, employing phenomenological interactions well
reproduced the experimentally observed transitions
just below 3 MeV as two excited 2+ states feeding the ground state independently. These theoretical predictions interpret the experimental result as
78
Ni having two coexisting shapes, spherical in the
ground-state band and prolate for the excited band,
respectively. Other theoretical approaches, such as
the QRPA, Coupled-Cluster, and In-Medium SRG calculations, could solely reproduce the ﬁrst 2+ state at
2,600 keV as spherical shape. The absence of the second 2+ state found at 2,910 keV is understood as due

80

a 79Cu(p,2p)78Ni
Mγ < 6583(10)60
1,103(14)40
1,540(30) 2,110(50) 2,600(33)Counts / 80 keV20

0b 80Zn(p,3p)78Ni
Mγ < 4
1,067(17)20

2,910(43)

10

0

1,000

2,000

3,000

4,000

5,000
Energy (keV)

Fig. 1. Doppler-corrected γ-ray spectra of 78 Ni for the(p, 2p) and (p, 3p) channels. These histograms are
fitted with simulated response functions (light bluelines) and double-exponential background curves (bluedashed line). The labels indicate the energies of therespective peaks. Solid response function lines had significance levels above 3σ, while the dotted ones did not.
The magenta line in each panel shows the summed curveof the simulated functions.

to the limitations of these models such that they do
not incorporate the deformed, or collective phenomena. This study suggests that the neutron-rich isotope
78
Ni cannot be envisaged as a simple doubly closedshell nucleus, but rather having a competing deformed
structure that prevails for more neutron-rich Ni isotopes and N = 50 isotones.
References

1) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 3C003(2012).
2) A. Obertelli et al., Eur. Phys. J. A 50, 8 (2014).
3) S. Takeuchi et al., Nucl. Instrum. Methods Phys. Res.
A 763, 596 (2014).

Condensed from the article in Nature 569, 53–58 (2019)
Department of Physics, The University of Tokyo
RIKEN Nishina Center
IRFU, CEA, Université Paris-Saclay
Institut für Kernphysik, Technische Universität Darmstadt-3-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Inclusive cross sections for one- and multi-nucleon removal from Sn, Sb,
and Te projectiles beyond the N = 82 shell closure†
V. Vaquero,∗1 A. Jungclaus,∗1 J. L. Rodríguez-Sánchez,∗2 J. A. Tostevin,∗3 P. Doornenbal,∗4 K. Wimmer,∗5,∗4
S. Chen,∗4,∗6 E. Nácher,∗1 E. Sahin,∗7 Y. Shiga,∗8 D. Steppenbeck,∗4 R. Taniuchi,∗4,∗5 Z. Y. Xu,∗9 T. Ando,∗5
H. Baba,∗4 F. L. Bello Garrote,∗7 S. Franchoo,∗10 A. Gargano,∗11 K. Hadynska-Klek,∗7 A. Kusoglu,∗12,∗13 J. Liu,∗9T. Lokotko,∗9 S. Momiyama,∗5 T. Motobayashi,∗4 S. Nagamine,∗5 N. Nakatsuka,∗14 M. Niikura,∗5 R. Orlandi,∗15
T. Saito,∗5 H. Sakurai,∗4,∗5 P. A. Söderström,∗4 G. M. Tveten,∗7 Zs. Vajta,∗16 and M. Yalcinkaya∗1,∗12
Inclusive one- and multi-nucleon removal cross sections have been measured for several Sn, Sb and Te isotopes just beyond the N = 82 neutron shell closure.
The beams were produced in the projectile ﬁssion of a238
U beam at the Radioactive Isotope Beam Factory at
RIKEN. The experimental cross sections were compared
to predictions from two diﬀerent versions of the Liege intranuclear cascade (INCL) model1,2) as shown in Fig. 1.
This ﬁgure shows an overall good agreement between
the calculations and the experimental results. In particular for the 0pxn removal from the N = 83 projectiles
133
Sn, 134 Sb, and 135 Te as well as the stable 112 Sn3) boththe magnitude and the gentle odd-even staggering of thecross sections is nicely reproduced by both calculations.
In contrast, none of them correctly describes the measured cross sections for one- and two-neutron removalfrom the N = 84 isotones 134 Sn and 135 Sb. This failure of the INCL model could be traced to the peculiar
structure of these nuclei with only a few valence neutrons
above the N = 82 shell gap.4)
Turning now to the one-proton knockout cross sections, Fig. 1(b) clearly shows that both calculations failto reproduce the experimental values for all three studied N = 84 projectiles, i.e. 134 Sn, 135 Sb and 136 Te. Note,however, that in this case the reﬁnements, which havebeen introduced in the modiﬁed version of the INCL
code, have a much stronger eﬀect as compared to thecase of one-neutron knockout, reducing the calculated
one-proton knockout cross sections by roughly a factorof two. The underlying reasons for the overestimation of
the cross section for the removal of the stronger boundnucleon species by the INCL model, which had alreadybeen recognized in the past, are still awaiting explana-Fig. 1. Comparison between experimental inclusive removal
cross sections and the results of calculations performed
with two diﬀerent versions (standard1) as dashed blue
and modiﬁed2) as solid black lines) of the INCL code
for a) the 0pxn and b) the 1pxn removal channels. The
experimental cross sections for 0pxn removal from 112 Sn
shown in a) are taken from Ref. 3).

tion. The present data for multi-nucleon removal indicate that an ad-hoc increase of the excitation energy
in the INCL model at the end of the cascade process,an approach which has been suggested to cure the incapacity of the model to correctly describe the removalof deeply bound nucleons, does not address the origin of
this problem.
Finally, we mention that the experimental inclusive
cross section for one-proton removal from semi-magic134
Sn was also compared with calculations based on
eikonal direct reaction theory with structure information from the nuclear shell model and refer to the original publication for further details.

Condensed from the article in Phys. Lett. B 795, 356 (2019)
IEM-CSIC Madrid∗2 Universidad de Santiago de Compostela∗3 University of Surrey∗4 RIKEN Nishina Center∗5 Department of Physics, University of Tokyo∗6 Peking University, Bejing∗7 University of Oslo, Oslo
∗8 Department of Physics, Rikkyo University∗9 University of Hong Kong
∗10 IN2P3-CNRS, Orsay∗11 INFN, Napoli∗12 Istanbul University∗13 ELI-NP, Magurele∗14 Department of Physics, Kyoto University∗15 Advanced Science Research Center, JAEA
∗16 MTA Atomki†∗1

References

1) D. Mancusi et al., Phys. Rev. C 90, 054602 (2014).
2) J. L. Rodríguez-Sánchez et al., Phys. Rev. C 96, 054602(2017).
3) L. Audirac et al., Phys. Rev. C 36, 041602(R) (2013).
4) V. Vaquero et al., Phys. Rev. Lett. 118, 202502 (2017).

-4-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

g-Factor of the 99 Zr isomer: monopole evolution in the shape-coexistingregion†F. Boulay,∗1,∗2,∗3 G. S. Simpson,∗4 Y. Ichikawa,∗2 S. Kisyov,∗5 D. Bucurescu,∗5 A. Takamine,∗2 D. S. Ahn,∗2
K. Asahi,∗2,∗6 H. Baba,∗2 D. L. Balabanski,∗2,∗7 T. Egami,∗2,∗8 T. Fujita,∗2,∗9 N. Fukuda,∗2 C. Funayama,∗2,∗6
T. Furukawa,∗2,∗10 G. Georgiev,∗11 A. Gladkov,∗2,∗12 M. Hass,∗13 K. Imamura,∗2,∗14 N. Inabe,∗2 Y. Ishibashi,∗2,∗15
T. Kawaguchi,∗2,∗8 T. Kawamura,∗9 W. Kim,∗12 Y. Kobayashi,∗16 S. Kojima,∗2,∗6 A. Kusoglu,∗11,∗17 R. Lozeva,∗11
S. Momiyama,∗18 I. Mukul,∗13 M. Niikura,∗18 H. Nishibata,∗2,∗9 T. Nishizaka,∗2,∗8 A. Odahara,∗9 Y. Ohtomo,∗2,∗6
D. Ralet,∗11 T. Sato,∗2,∗6 Y. Shimizu,∗2 T. Sumikama,∗2 H. Suzuki,∗2 H. Takeda,∗2 L. C. Tao,∗2,∗19 Y. Togano,∗6
D. Tominaga,∗2,∗8 H. Ueno,∗2 H. Yamazaki,∗2 X. F. Yang,∗20 and J. M. Daugas∗1,∗2
0.03
0.02
0.01

R(t)

A rapid change of the ground-state shape has been
known to occur in neutron-rich Zr isotopes between thespherical 98 Zr and deformed 100 Zr.1) This change has
been described as a quantum phase transition (QPT)
with the neutron number as a control parameter. The
99
Zr nucleus closest to the critical point of the QPT has
an isomer (99m Zr) with a spin parity of 7/2+ at 252 keV.
The interaction between the πg9/2 and νg7/2 orbitals has
been thought to be important for this QPT to occur,2)
and the 7/2+ state may be key to this mechanism. In
the present study, the nature of 99m Zr was investigatedthrough the magnetic moment.
The magnetic-moment measurement was performedat the BigRIPS at RIBF. 99m Zr was produced and spinaligned via the abrasion-ﬁssion of a 345-MeV/nucleon
238
U beam impinged on a 100-µm-thick 9 Be target. The
g-factor of 99m Zr was measured by the time-diﬀerential
perturbed angular distribution (TDPAD) method. Figure 1 shows the R(t) ratio evaluated using γ rays of
130 keV and 122 keV by assuming pure M 1 and E2 transitions, respectively, where a degree of spin-alignment of
1.5(4)% was extracted. The g factor of 99m Zr determined
was determined as |g| = 0.66(4); thus, the magnetic moment is |µ| = 2.31(14) µN .
This value is far from the Schmidt value of gfree =+0.425 for the νg7/2 orbital, indicating that 99m Zr is
not in a pure (νg7/2 )1 state. A comparison of the exper-

0
-0.01
-0.02
-0.03
200

400

600

800

1000

1200

1400

Time (ns)Fig. 1. R(t) ratio associated with two γ rays.

7/2+

7/2+

252 |μ|=2.31(14)μN
B(E2)=1.16(3) W.u.

3/2+

122 |μ|=0.42(6)μN
B(M1)=0.0102(3) W.u.
0 μ=-0.930(4)μN

1/2+

Exp.

441 μ=2.08μN

B(E2)=2.66 W.u.

3/2+
1/2+

B(M1)=0.0109 W.u.
30 μ=0.38μN
0 μ=-1.29μN

IBFM-1

Fig. 2. Comparison between experimental and theoreticalvalues. The IBFM-1 calculation is based on the transition probabilities among the lowest three states and themagnetic moments of the lowest two states.3)

Condensed from the article in Phys. Rev. Lett. 124, 112501(2020)∗1 CEA, DAM, DIF∗2 RIKEN Nishina Center∗3 GANIL, CEA/DSM-CNRS/IN2P3∗4 LPSC, CNRS/IN2P3, Université Joseph Fourier Grenoble 1∗5 IFIN-HH∗6 Department of Physics, Tokyo Institute of Technology∗7 ELI-NP, IFIN-HH∗8 Department of Advanced Sciences, Hosei University∗9 Department of Physics, Osaka University∗10 Department of Physics, Tokyo Metropolitan University∗11 IJCLab, CNRS/IN2P3, Université Paris-Saclay∗12 Department of Physics, Kyungpook National University∗13 Department of Particle Physics, Weizmann Institute∗14 Department of Physics, Meiji University∗15 Department of Physics, University of Tsukuba∗16 Department of Informatics and Engineering, University ofElectro-Communications∗17 Department of Physics, Istanbul University∗18 Department of Physics, University of Tokyo∗19 School of Physics, Peking University∗20 Intsituut voor Kern-en Stralingsfysica, K. U. Leuven†

imental values with the results of the interacting bosonfermion model (IBFM-1), as shown in Fig. 2, suggeststhat this state is strongly mixed with the main composition being νd5/2 . Furthermore, we found that monopole
single-particle evolution changes signiﬁcantly with theappearance of collective modes.4,5)
References

1) P. Campbell et al., Phys. Rev. Lett. 89, 082501 (2002).
2) P. Federman, S. Pittel, Phys. Lett. B 69, 385 (1977).
3) P. Spagnoletti et al., Phys. Rev. C 100, 014311 (2019).
4) Y. Tsunoda et al., Phys. Rev. C 89, 031301(R) (2014).
5) T. Togashi et al., Phys. Rev. Lett. 117, 172502 (2016).

-5-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Study of quasielastic barrier distributions as a step towards thesynthesis of superheavy elements with hot fusion reactions†
T. Tanaka,∗1,∗2,∗3 K. Morita,∗1,∗2 K. Morimoto,∗1 D. Kaji,∗1 H. Haba,∗1 R. A. Boll,∗4 N. T. Brewer,∗4
S. Van Cleve,∗4 D. J. Dean,∗4 S. Ishizawa,∗1,∗5 Y. Ito,∗1,∗6 Y. Komori,∗1 K. Nishio,∗1,∗6 T. Niwase,∗1,∗2
B. C. Rasco,∗4 J. B. Roberto,∗4 K. P. Rykaczewski,∗4 H. Sakai,∗1 D. W. Stracener,∗4 and K. Hagino∗7,∗8,∗9
The excitation functions of quasielastic scatteringcross sections for reactions relevant to the syntheses of superheavy nuclei, that is, the 22 Ne+248 Cm,26
Mg+248 Cm, and 48 Ca+238 U systems, were measured
using the gas-ﬁlled recoil ion separator GARIS to understand systematically the reaction dynamics of the
hot fusion reactions. From the measured cross sections,the barrier distribution was extracted, which shows a
distribution of the barrier height in the entrance channel. The experimental data were well reproduced by
the coupled-cannels calculations.1) The calculated results indicate that the shape of barrier distribution isaﬀected dominantly by deformation of the actinide target nuclei, but also by vibrational/rotational excitations of the projectile nuclei as well as neutron transfer processes before capture. Contribution from eachcolliding angles to the barrier distribution is systematically shown in Fig. 1 (black thin solid curves) byshowing the barrier distribution from each collidingangle range with 10◦ interval. Here, the distribution
for the side collision 80–90◦ is highlighted by the reddashed curve. The total barrier distributions, which
are the sum of the black thin solid curves and the reddashed curves, are also shown by the blue solid curves.
The peak of the sum of the evaporation residue crosssections for Sg (Z = 106),2–6) Hs (108),7) Cn (112)8,9)
and Lv (116)8,10)a) coincide not only with the barrier
distribution for 80–90◦ , but also with that for 70–80◦
etc. However, the overlap with the barrier distribution
for the tip collision, such as 0◦ –20◦ , is negligibly small,indicating that these hot fusion reactions take advantage of the compact collision, where the projectile approaches along the short axis of a prolately deformed
nucleus, as was discussed in Refs. 11–13).
For hot fusion reactions, the optimum incident energy, at which the evaporation residue cross section
†
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9
a)

0.12
0.10
0.08
0.06
0.04
0.02
0.00
-0.02

-d(dσQE /dσR )/dE

22

Ne+248Cm

26

σER (pb)

Sg (106)
102

101
100

110

120

48
Exp.
Ca+238U
Cal. (total)
Cal. (80 - 90 deg)Cal. (every 10 deg)

Mg+248Cm

Hs (108)
101

101

100

100

10-1

10-1

110 120 130 140
Ec.m. (MeV)

Upper limit Cn (112)
3n
4n
5n

170 180 190 200 210

Fig. 1. A comparison between the measured quasielastic
barrier distributions (the upper panels) and the evaporation residue cross sections reported at diﬀerent centerof-mass energies for the syntheses of Sg, Hs, and Cn2–9)(the lower panels). The red symbols indicate the experimental data from this work. The detailed explanationsof the calculated results are described in main text.

is maximized, can be estimated by an experimentally
determined barrier distribution, if the trend of compact collision is not changed. Importantly, it would
take only about one day to measure a barrier distribution for one reaction, which is much shorter than atypical experiment to synthesize new superheavy element, e.g., more than one hundred days using one pµA
beam. This new method will signiﬁcantly contributeto future experiments to synthesize both new superheavy elements and superheavy nuclei in the island ofstability.
References
1) K. Hagino et al., Comput. Phys. Commun. 123, 143(1999).
2) Yu. A. Lazarev et al., Phys. Rev. Lett. 73, 624 (1994).
3) A. Türler et al., Phys. Rev. C 57, 1648 (1998).
4) R. Dressier et al., PSI Rep. 1, 130 (1999).
5) S. Hübener et al., Radiochimica Acta 89, 737 (2001).
6) H. Haba et al., Phys. Rev. C 85, 024611 (2012).
7) J. Dvorak et al., Phys. Rev. Lett. 100, 132503 (2008).
8) Y. T. Oganessian et al., Phys. Rev. C 70, 064609 (2004).
9) S. Hofmann et al., Eur. Phys. J. A 32, 251 (2007).
10) S. Hofmann et al., Eur. Phys. J. A 48, 62 (2012).
11) D. J. Hinde et al., Phys. Rev. Lett. 74, 1295 (1995).
12) K. Nishio et al., Phys. Rev. C 62, 014602 (2000).
13) T. Tanaka et al., J. Phys. Soc. Jpn. 87, 014201 (2018).

Condensed from the article in Phys. Rev. Lett. 124, 052502(2020)RIKEN Nishina Center
Department of Physics, Kyushu University
Department of Nuclear Physics, The Australian National
University
Oak Ridge National Laboratory
Graduate School of Science and Engineering, Yamagata University
Advanced Science Research Center, JAEA
Department of Physics, Tohoku University
Research Center for Electron Photon Science, Tohoku University
Department of Physics, Kyoto University
The result of 48 Ca+248 Cm→296 Lv* is omitted from theFig. 1 due to the space limit. See the original article.

-6-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Location of the neutron dripline at fluorine and neon†
D. S. Ahn,∗1 N. Fukuda,∗1 H. Geissel,∗5 N. Inabe,∗1 N. Iwasa,∗4 T. Kubo,∗1,a K. Kusaka,∗1 D. J. Morrissey,∗6
D. Murai,∗3 T. Nakamura,∗2 M. Ohtake,∗1 H. Otsu,∗1 H. Sato,∗1 B. M. Sherrill,∗6 Y. Shimizu,∗1 H. Suzuki,∗1
H. Takeda,∗1 O. B. Tarasov,∗6 H. Ueno,∗1 Y. Yanagisawa,∗1 and K. Yoshida∗1
The location of the neutron dripline has been a longstanding issue, and it is only known up to oxygen (atomic
number Z = 8) so far. No conﬁrmed extensions of thedripline above Z = 8 have been made for nearly 20 years,
since 24 O (neutron number N = 16) was determined to
be a dripline nucleus.
In order to investigate the neutron dripline for higherZ elements such as ﬂuorine (Z = 9), neon (Z = 10), andsodium (Z = 11), we conducted a search for the new isotopes 32, 33 F, 35, 36 Ne, and 38, 39 Na at the RIKEN RIBF.
We attempted to observe isotopes beyond the line of themass number A = 3Z + 4, where the most neutron-richisotopes known so far are located. The search was performed using the projectile fragmentation of an intense48
Ca beam at 345 MeV/nucleon on a 20-mm-thick beryllium target. The projectile fragments were separated
and identiﬁed in ﬂight by the large-acceptance two-stage
fragment separator BigRIPS.1,2) The 48 Ca-beam intensity was as high as ∼450 particle nA (∼ 3 × 1012 particles/s).
Particle identiﬁcation was performed at the second
stage of the BigRIPS separator, relying on the combination of time of ﬂight (TOF), magnetic rigidity (Bρ),
and energy loss (∆E) measurements, from which the Z
and A/Z of the fragments were deduced.3) The TOF was
measured between two thin plastic scintillators installedat the intermediate and ﬁnal foci of the second stage.
The ∆E was measured using a stack of four identical silicon semiconductor detectors installed at the ﬁnal focus.
The Bρ was determined from a position measurement at
the intermediate focus using the same plastic scintillator.
The measurement was conducted with two Bρ settingsof the BigRIPS separator, the central particle of which
was tuned to be 33 F and the middle of 36 Ne and 39 Na,
respectively. In these settings, their neighboring isotopes
also had a reasonably good transmission.
a)After extensive running, we observed no events forF, 35, 36 Ne, and 38 Na and one event for 39 Na, implying that these unobserved isotopes were particle unbound. In order to assess the conﬁdence level of the implication, production cross sections were systematicallymeasured as a function of mass number, and the data
were compared with the predictions from the EPAX 2.15

32, 33

†
∗1
∗2
∗3
∗4
∗5
∗6
a

Condensed from the article in Phys. Rev. Lett. 123, 212501(2019)RIKEN Nishina Center
Department of Physics, Tokyo Institute of Technology
Department of Physics, Rikkyo University
Department of Physics, Tohoku University
GSI, Helmholtzzentrum für Schwerionenforschung GmbH
National Superconducting Cyclotron Laboratory, Michigan
State University
Corresponding author-7-

Fig. 1. Section of the nuclear chart showing the location of
the neutron dripline determined in the present work.

systematics4) and the Qg systematics.5) These systematics allowed us to extrapolate the observed cross sections
and, hence, estimate the expected yields of the unobserved isotopes. The comparison of no observed eventswith the expected yields revealed that the existence ofbound 32, 33 F, 35, 36 Ne, and 38 Na was excluded with highconﬁdence levels. Thus, we concluded that the mostneutron-rich and heaviest bound nuclei, corresponding
to the dripline nuclei, are 31 F and 34 Ne for ﬂuorine andneon, respectively. The location of the neutron dripline
has thus been extended up to Z = 10 for the ﬁrst timein nearly 20 years, as shown in Fig. 1.
The location of the neutron dripline is sensitive to theunderlying nuclear structure of neutron-rich exotic nuclei, such as the evolution of nuclear shell structure andoccurrence of nuclear deformation, which are caused by
the characteristic eﬀects of complex nuclear forces.6–8)
We compared the present results with various nuclear
mass and structure models, and we found that no models could consistently account for the nuclear binding of
neutron-rich nuclei in the present Z region.
The present results provide new keys to understanding
the nuclear stability at extremely neutron-rich conditions
and also present a new challenge to nuclear mass models
as well as nuclear structure theories and calculations.
References

1) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
2) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 03C003(2012).
3) T. Ohnishi et al., J. Phys. Soc. Jpn. 77, 083201 (2008).
4) K. Sümmerer, B. Blank, Phys. Rev. C 61, 034607 (2000).
5) O. B. Tarasov et al., Phys. Rev. C 75, 064613 (2007).
6) D. S. Ahn et al., Phys. Rev. Lett. 123, 212501 (2019) andreferences therein.
7) T. Otsuka, Phys. Scr. T 152, 014007 (2013).
8) T. Otsuka et al., arXiv:1805.06501v5 [nucl-th] 2 Jan 2020.

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Dineutron correlation and rotational excitations in neutron-rich Mg
isotopes
M. Yamagami ∗1
The spatial two-neutron correlation between two
weakly-bound neutrons, called dineutron correlation, is
one of the unique features of nuclei around the neutron
drip line. It is considered to be a universal phenomenon
that appears over all mass-number regions. However,experimental probes for this phenomenon are still underintense debate, except for light-mass nuclei such as 11 Li.
In this study, the inﬂuences of the novel pairing eﬀect
on rotational excitations in neutron-rich Mg isotopes areclariﬁed.
The experimental moment of inertia (MOI), which
can be extracted from the excitation energy E(2+1 ), issmaller than the rigid-body values by a factor of 2 to 3.
The most important inﬂuences in this respect are pairing correlations. I calculate the Thouless-Valatin (TV)
MOI, which includes the pairing correlations and residual interactions within the framework of the quasiparticle random phase approximation (QRPA).
The Hartree-Fock-Bogoliubov (HFB) equation with
the Skyrme energy density functional (EDF) is solvedin the three-dimensional wave-number mesh space.1) On
top of the HFB states, the QRPA equation in the A-B
matrix form1) is solved for the TV MOI:∑′
(1)(Jx )∗kk′ (A + B)−1
ITV = 2kk′ ,ll′ (Jx )ll .

Fig. 2. Same as Fig. 1 but for the Thouless-Valatin (TV),Belyaev, and experimental MOIs. They are divided by
the empirical value.

and 0.15 respectively. Figure 1 shows the neutron pairing gaps ∆n in neutron-rich Mg isotopes. The pairing gaps ∆n are almost constant in calculation using
the surface-type pairing force. This pairing force has astrong continuum-coupling eﬀect and creates dineutron
correlation around 40 Mg.1,2) The continuum-coupling effect is weak in the volume-type pairing force, and theneutron pairing gaps ∆n decrease as a function of mass
number A.
Figure 2 shows the TV MOIs in neutron-rich Mg
isotopes. The Belyaev MOIs, in which the residualinteractions in QRPA are neglected, are also shown.
They are divided by the empirical value Iemp =β 2 A7/3 /400 [MeV−1 ]. The TV MOIs using the surfacetype pairing force agree well with the experimental values, whereas the Belyaev MOIs underestimate the experimental values by about 20%.
The ratios of TV MOIs ITV /Iemp are almost constantin Mg isotopes with A ≤ 40, but they are substantiallyenhanced in 42, 44 Mg owing to the weak-binding eﬀect.
In conclusion, it is emphasized that the experimental
MOIs in neutron-rich Mg isotopes are well reproduced by
the TV MOIs using the surface-type pairing force, which
creates dineutron correlations. The diﬀerence between
the TV MOIs using the surface-type and volume-type
pairing forces increases on approaching the neutron drip
line, and the diﬀerence is 20.7% in 44 Mg.

kk′ ,ll′

The Skyrme SkM* EDF predicts the neutron drip
line at 44 Mg.
The quadrupole deformations of34, 36, 38, 40, 42, 44
Mg are β = 0.35, 0.30, 0.28, 0.28, 0.21,

Fig. 1. Neutron pairing gaps ∆n in neutron-rich Mg isotopes.
The results obtained using the surface-type and volumetype pairing forces are compared with the experimental
data.
∗1

References

1) M. Yamagami, Phys. Rev. C 100, 054302 (2019).
2) M. Yamagami et al., Phys. Rev. C 77, 064319 (2008).

Department of Computer Science and Engineering, Universityof Aizu-8-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

xF dependence of the transverse single spin asymmetry of very forward
π 0 production in 510 GeV p↑ + p collisions

The transverse single spin asymmetry, AN , of very
forward (η > 6) π 0 was ﬁrst measured in the RHICf
1)
in June, 2017 from polarized p + p colliexperiment√sions at s = 510 GeV. The AN is deﬁned as (dσLeft −dσRight )/(dσLeft +dσRight ), where σLeft(Right) is the particle production cross sections in the left (right) side of
the polarization direction of the proton beam. The ANof very forward π 0 is a powerful observable to investigate the contribution from the non-perturbative process
to the non-zero AN of π 0 , which has been measured inmany experiments2–4) thus far.
In order to measure the very forward π 0 precisely, anelectromagnetic calorimeter, the RHICf detector, wasinstalled at the zero-degree area of the STAR experiment at Relativistic Heavy Ion Collider, which was 18 m
away from the beam collision point. The conﬁgurationof the RHICf detector can be found in Ref. 5). The
RHICf detector has an energy resolution of 2.5–3.5%
for 100–250 GeV π 0 and a transverse momentum (pT )resolution of 0.005–0.025 GeV/c for 0.0–0.8 GeV/c π 0 .
The experiment was conducted for 28 h with threevertical detector positions, where the beam propagatedtowards the center of the large tower, center of the small
tower, and a point 24 mm below the center of the small
tower of the detector before the collisions. With thethree detector positions, we requested radial polarization, which was the direction at an angle of 90◦ fromthe usual vertical polarization at RHIC, and a large β ∗= 8 m so as to measure the wide pT range with higher
resolution. The kinematic coverage of the measured π 0
is xF > 0.25 and 0.0 < pT < 1.0 GeV/c, where the nonperturbative process was expected to mainly contributeto the π 0 production.
Figure 1 shows our preliminary result for the AN ofvery forward π 0 as a function of xF for ﬁve diﬀerent
pT ranges. The line and box error bars represent statistical and systematic uncertainties, respectively. The
estimation; of the polarization; beam center, which isdeﬁned as the extrapolated zero-degree position of thebeam to the detector; and background (mostly from thetwo-photon coincidence of diﬀerent π 0 ) were the threemain systematic sources. See Ref. 6) for more details
on the analysis procedure and systematic study.
In Fig. 1, the AN s are consistent with zero at a very
low pT < 0.09R GeV/c. However, its slope with respect
to the xF -axis becomes steeper as pT increases. WhenpT > 0.36 GeV/c, the increasing AN shows the same
slope with the previous forward (2 < η < 4) π 0 measurements2–4) even in the low-pT region where only the
∗1
∗2

AN

M. H. Kim∗1,∗2 for the RHICf collaboration

0.25
0.2

RHICf Preliminaryp↑+p → π0+X at s = 510 GeV (6 < η)
0.00 < pT < 0.09 GeV/c

0.15

0.09 < pT < 0.17 GeV/c
0.17 < p < 0.36 GeV/c

0.1

0.36 < pT < 0.59 GeV/c
0.59 < p < 1.00 GeV/c

T

T

0.05
0
−0.05
0

0.2

0.4

0.6

0.8
xF

Fig. 1. Preliminary result of the AN of very forward π 0 production as a function xF . The ﬁve diﬀerent colors correspond to diﬀerent pT ranges.

non-perturbative process is expected to be dominant.
It might be possible that the non-perturbative process
can contribute to the non-zero AN of π 0 at a higher pT .
The result also raises the necessity of further experimental eﬀorts to compare the roles of the perturbativeand non-perturbative processes in the AN of π 0 andthe measurement of the intermediate kinematic region
where both processes possibly contribute (0.8 < pT <2.0 GeV/c). Combined analysis with STAR forward andRoman pot7) detectors is useful to separate each process by measuring the rapidity gap or tagging a proton
scattered at a very low angle, which are the characteristics of the diﬀraction of the non-perturbative process.
References

1) RHICf Collaboration, arXiv: 1409.4860 [physics.ins-det].
2) D. L. Adams et al. (FNAL-E581 and E704 Collaborations), Phys. Lett. B 261, 201 (1991).
3) A. Adare et al. (PHENIX Collaboration), Phys. Rev. D
90, 012006 (2014).
4) B. I. Abelev et al. (STAR Collaboration), Phys. Rev. D
101, 222001 (2008).
5) M. H. Kim for the RHICf Collaboration, RIKEN Accel.
Prog. Rep. 52, 83 (2019).
6) M. H. Kim for the RHICf Collaboration, arXiv:1902.07852[hep-ex].
7) S. Bültmann et al. Nucl. Instrum. Methods Phys. Res.
535, 415 (2004).

Department of Physics, Korea University
RIKEN Nishina Center-9-Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Non-evaporable getter-based diﬀerential pumping system for SRILAC
H. Imao,∗1 K. Yamada,∗1 N. Sakamoto,∗1 T. Watanabe,∗1 Y. Watanabe,∗1 K. Oyamada,∗2 A. Yusa,∗2
and O. Kamigaito∗1
Upgrades of the RIKEN heavy-ion linac (RILAC) involving a new superconducting linac (SRILAC1) ) are in
progress. High-vacuum (<10−8 Pa) and particulate-free
conditions are strictly necessary for keeping the performance of the superconductive radio frequency (SRF)
cavities of SRILAC. It is crucially important to develop
neighboring warm sections to mitigate the large diﬀerence in the vacuum and clean conditions with respect tothe existing old RILAC and beamlines built almost four
decades ago. In the present study, a non-evaporable getter (NEG)-based diﬀerential pumping system (DPS) has
been developed.
The three-stage DPS (Fig. 1) was designed to achievea pressure reduction from the existing beamline vacuum(10−5 –10−6 Pa) to an ultra-high vacuum of less than
10−8 Pa in the SRF cavities within a very limited lengthof only 75 cm, ensuring a beam aperture greater than
40 mm. The properties of pumps we used for the DPS
are summarized in Fig. 1. Optimizations of the design
were performed with Molﬂow+2) . We measured the pressures of three stages in a prototype DPS when we leakedN2 and H2 with three diﬀerent leak rates, respectively.
The observed pressures are in good agreement with thecalculated ones (Fig. 2). The DPS also has fast closing gate valve (Series 75.2; VAT Group AG) responses
within 10 ms after receiving the signal of the pressure riseof three distributed cold-cathode gauges to protect the
SRF systems from unexpected vacuum breaks. Compact
electrostatic particle suppressors (EPSs) were equipped
at the inside of the ﬁrst-stage chambers of the DPSs to
suppress the scattering of particles and reduce possibili-

Fig. 1. Design of three-stages DPS and pump properties.
∗1∗2

RIKEN Nishina Center
Sumitomo Heavy Industries Accelerator Science Ltd.

Fig. 2. Pressure distributions for N2 and H2 leakage.

Fig. 3. Photograph of the DPS and the EPS.

ties to transport particles to the SRF cavities. The EPS
consists of two electrodes, each of which consists of 6
stainless-steel bars, as shown in Fig. 3. Some particle
tests with the EPS in air and vacuum were performed
with a vacuum particle sensor (VACUUM PARTICLESENSOR; Wexx Co., Ltd). Ceramic and metal particles were artiﬁcially generated by scraping blocks. The
counts were signiﬁcantly reduced when we applied a highvoltage on the electrodes. The vacuum in the beamlines
becomes an ionizing environment due to the energetic
heavy ions passing during the operation. We expect that
the EPS can suppress particle transport to the SRF cavities.
All components (chambers, pumps, valves, vacuum
gauges, etc.) were cleaned and assembled in a clean
room of ISO class 1. The installation of the pair DPSs
was completed in December 2019. Some pumps areequipped in the horizontal direction to prevent particle falls (Fig. 3). We already conﬁrmed that the desiredpressure reductions were successfully achieved, and actual operations will start soon.
References

1) N. Sakamoto et al., Proc. LINAC’18, Beijing, WE2A03(2017).
2) Molflow+, http://molflow.web.cern.ch/ .
- 10 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Calibration of the beam energy position monitor system for the RIKEN
superconducting acceleration cavity†
T. Watanabe,∗1 H. Imao,∗1 O. Kamigaito,∗1 N. Sakamoto,∗1 N. Fukunishi,∗1 M. Fujimaki,∗1 K. Yamada,∗1
Y. Watanabe,∗1 T. Toyama,∗2 T. Miyao,∗2 A. Miura,∗3 K. Hanamura,∗4 T. Kawachi,∗4 R. Koyama,∗5
and A. Kamoshida∗1,∗6
Upgrades for the RIKEN Heavy-ion Linac that involvea new Superconducting Linac (SRILAC) are currently
underway to promote super-heavy element searches andthe radioactive isotope (RI) production of astatine(211 At) for medical use.1,2) We have developed a beamenergy position monitor (BEPM) system3) that can simultaneously measure not only the beam position but
also the beam energy by measuring the time of ﬂight ofthe beam. By using parabolic-shaped electrodes (Fig. 1),
we realized the ideal linear response of the quadrupole
moments while maintaining good linear position sensitivity. We fabricated 11 BEPMs and a position calibration system employing the wire method that we used toobtain the sensitivity and oﬀset of the BEPMs.
Destructive monitors generate outgassing; if they areused, it becomes diﬃcult to maintain the Q value andsurface resistance of the superconducting radio frequency(SRF) cavities over a long period of time. It is, therefore,
crucial to develop nondestructive beam measurement diagnostics. With the aim of measuring the beam position
at an overall accuracy of ± 0.1 mm, a calibration measurement was performed at the KEK campus in Tokai.
Because there are 3 types of BEPMs for the SRILAC,3)
we designed and fabricated dummy pipes that surroundthe wire and jigs to mechanically ﬁt the calibration device. The calibration device is shown in Fig. 2. The
BEPM to be calibrated is connected to a dummy pipewith an inner diameter equal to that of one of the BEPMs(Fig. 2(a)). The assembly is ﬁxed to an XY stage thatmoves within the measurement region in 2-mm steps. A
wire acting as a signal source is ﬁxed. Round crimp terminals are attached by crimping and soldering at both

Cross
SectionElectrodeCeramic
Insulator

SMA
FeedthroughFig. 1. Parabolic-shaped electrodes.
†
∗1
∗2
∗3
∗4
∗5
∗6

Condensed from the the proceedings in 2019 International
Beam Instrumentation Conference (IBIC 2019)
RIKEN Nishina Center
KEK/J-PARC, Tokai
JAEA/J-PARC, Tokai
Mitsubishi Electric System & Service Co., Ltd., TokaiSHI Accelerator Service Ltd., Wako
National Instruments Japan Corporation, Tokyo

Type Ⅲy(a)x

To Network
Analyzer(b)(b)

Fig. 2. Photographs of the calibration measurement device,
jigs, and dummy pipes.

ends of a copper-plated piano wire. The dummy duct
has a double-pipe structure that can be expanded andcontracted. When the round-crimp terminals are connected to the electrode on both end plates, the innerdummy pipes are made to slide into the outer dummy
pipe to provide suﬃcient space for the connection of theelectrodes. After that operation is completed, the inner dummy pipes are restored to their original position
and ﬁxed to the double pipe by fastening bands. Adequate tension can be applied by moving one of the end
plates outward with ﬁne adjustment. The dummy pipes
are connected to the end plates with an RF contact ﬁnger and are held to the ground potential (Fig. 2(b)).
When the measurement was repeated, it was found thatboth the required electrical characteristics and ﬂexibility
could be achieved simultaneously by reducing the number of RF contact ﬁngers and applying copper tape tothe end plates. As a result, measurement errors weredrastically reduced.
By using the calibration device, the calibration wascompleted to within ±0.05 mm mechanical accuracy. We
will continue to analyze the measurement results of all
the BEPMs, which will be used to measure the beam
position and energy using the calibration values when
the beam is accelerated at SRILAC.
References

1) N. Sato et al., RIKEN Accel. Prog. Rep. 50, 262 (2017).
2) S. Yano et al., RIKEN Accel. Prog. Rep. 50, 263 (2017).
3) T. Watanabe et al., Proc. 15th Ann. Meet. of Particle
Accel. Soc. Jpn., Nagaoka, Japan, 2018-Aug. (2018), p. 49.

- 11 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Intermediate silicon tracker development for sPHENIX experiment at
RHIC
I. Nakagawa,∗1 Y. Akiba,∗1 D. Cacace,∗2 K. Cheng,∗3 E. Desmond,∗2 T. Hachiya,∗1,∗4 S. Hasegawa,∗5
T. Kondo,∗6 C. Kuo,∗3 M. Lenz,∗2 E. Mannel,∗2 C. Miraval,∗2 M. Morita,∗4 R. Nouicer,∗2 R. Pisani,∗2
M. Shibata,∗4 C. Shih,∗3 A. Suzuki,∗4 T. Todoroki,∗1 X. Wei,∗7 and R. Xiao∗7
The construction of sPHENIX detector1) has been
started since the sPHENIX was approved for the
Project Decision-2/3 (corresponds to DOE’s Critical
Decision-2/3) in May, 2019. The subsystem detectors
are now under mass production. We have been developing the one of the tracking devices of sPHENIX
called INTermediate Tracker (INTT), which consistedof 2 layers of a silicon strip sensor. The INTT is the
only tracker which has better than 1 beam clock resolution in sPHENIX trackers. It provides thus the timing of particle trajectories. A telescope was assembled
with 3 layers of prototype ladder for the ﬁrst beam testin March, 2018 at Fermilab test beam facility (FTBF).
The prototype detector demonstrated satisfactory position resolution as designed and about 96% detection
eﬃciency using well focused 120 GeV proton beam.
The design of silicon sensor and the high density interconnect readout cable were ﬁnalized after the ﬁrst
beam test. The next prototypes were considered as
pre-production versions and new silicon ladders wereassembled again to be tested in the next round beam

Fig. 2. The latest stave design (liquid cooling type).

test at FTBF in June, 2019. The performance ofthe pre-production ladders are discussed in Ref. 2).
The attempt to reproduce observed performance by
a GEANT MC simulation is in progress. The veryﬁrst attempt was made in this beam test to accumulate data with the full chain of the INTT readout system including the 1.2 meter long bus extension cable.3)
Technologically, it is the most challenging R&D of the
INTT project.
The stave is the support structure of the INTT module which consisted of silicon sensors and HDI. It requires not only the stiﬀness, but also high thermal
conductivity in order to remove heat generated fromthe read out chips mounted on the HDI. The stave ismade of a carbon ﬁber reinforced plastic and its prototyping has been proceeded in Asuka Co. in Japanand Lawrence Berkley National Laboratory in parallel. The latest stave is designed to be (Fig. 2) a liquid
cooling type using a carbon ﬁber composite tube laidout in the middle of the stave. The fabrication of thelatest design has been procured in Asuka Co.
The development of the INTT detector is thus in theﬁnal stage, the preparation for the mass production
is in progress. Produced all silicon sensors are to betested and evaluated in National Central University,
Taiwan.4) The ladder assembly is to be performed inboth National Taiwan University5) and BNL.6) The
mechanical design of the INTT ladders, readout chain,and support structure is discussed in Ref. 7).

Fig. 1. The INTT collaboration at the Fermilab test beamfacility in June 2019.
∗1
∗2
∗3
∗4
∗5
∗6
∗7

References

1) Conceptual Design Report of sPHENIX (2018).
2) A. Suzuki et al., in this report.
3) T. Hachiya et al., in this report.
4) K. Chen et al., in this report.
5) C. Shih et al., in this report.
6) M. Connor et al., in this report.
7) D. Cacace et al., in this report.

RIKEN Nishina Center
Brookhaven National Laboratory
National Central University
Nara Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University- 12 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Update of MOCO for the MPV system
H. Baba,∗1 T. Ichihara,∗1 T. Isobe,∗1 T. Ohnishi,∗1 K. Yoshida,∗1 Y. Watanabe,∗1 S. Ota,∗2 H. Shimizu,∗2
S. Shimoura,∗2 S. Takeuchi,∗2 D. Nishimura,∗3,∗2,∗1 J. Zenihiro,∗4,∗1 A. O. Tokiyasu,∗5 and R. Yokoyama∗6
We have been developing a data acquisition (DAQ)
system. VME-bus-based DAQ systems are widely utilized in RIBF. To speed up the VME DAQ system,a mountable controller (MOCO)1) was developed andintroduced in some experiments2) in 2016. We could
achieve very good DAQ performance; at the same time,
problems on the usability and robustness were found.
To establish a robust and easy-to-use system, we developed a new MOCO with parallelized VME (MPV),
which is a type of parallel readout extension of VME.3)
The system architecture is described in Ref. 3). In thiscontribution, we report the update of MOCO to adopt
the MPV system.
The original MOCO and new versions (prototype andproduction) of MOCO-MPV boards are shown in Fig. 1.
In the original MOCO, trigger and data communications
are performed using the LVDS I/O and USB interface.
On the other hand, these communications between the
MPV controller and MOCO-MPV are realized throughfour diﬀerential lines (LVDS I/O) that are patterned on
the MOCO-MPV board. These diﬀerential lines are
assigned as follows: 1) 100-MHz clock, 2) command
packet, 3) data packet A, and 4) data packet B. The
100-MHz clock and the command packets are distributed
from the controller. All commutations are synchronized(a) Original
MOCO(a) Prototype
MOCO-MPV

JTAG
USB(a) Production
MOCO-MPV

Debug
port

JTAG

LVDS
I/O PinDifferential
lines for
LVDS

Fig. 1. Photograph of diﬀerent versions of MOCO. The functionalities of the prototype and production MOCO-MPV
boards are the same. However, the positions of the JTAG
and debug port connectors are diﬀerent.
∗1
∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo
Department of Natural Sciences, Tokyo City University
Department of Physics, Kyoto University
ELPH, Tohoku University
Department of Physics and Astronomy, University of Tennessee- 13 -

Interrupt
from V792

BERR
from V792

34 words block transfer
between MOCO and V792

V792 Conversion �me
1 event busy ≈ 15us
Trigger �ming

Fig. 2. Monitor signals between MOCO and CAEN V792
QDC captured by Tektronix MDO3034 through the debug port of the prototype MOCO-MPV board.

with this 100-MHz clock. MOCO-MPV sends 200-Mbps
data at maximum by using two data packet lines to thecontroller. This 200-Mbps data throughput is suﬃcientbecause the maximum data rate of a typical 32-bit VME
module is 160 Mbps (in experiments at RIBF, this data
rate is usually much less than 20 Mbps per VME module). An eight-port debug interface is additionally implemented on the MOCO-MPV board to monitor the bus
signals between MOCO and a VME module. Figure 2
shows the signals of MOCO-MPV reading out data fromCAEN V792 QDC. MOCO-MPV waits for the interrupt
signal of V792, and the block transfer is started when
the interrupt signal is issued. After 34×32-bit data readout, the BERR signal is generated from V792, following
which this block transfer is terminated. Including theconversion time of V792, the duration of the one event
busy is only 15 µs. In the original MOCO case, DC
power is supplied via the DIN41612 female connector(right-side connector) because the board is designed toplace the front side of the VME backplane. In contrast,
since the MOCO-MPV board is installed at the rear side,both DC power and VME bus signals pass through the
DIN41612 male connectors (two left-side connectors).
The MPV system with the prototype MOCO-MPV
board was successfully introduced in the NP1512RIBF79R1-02 experiment4) in November 2019 for theﬁrst time. Legacy VME DAQ systems in RIBF will be
gradually replaced by the MPV system together withthe production MOCO-MPV board.
References

1) H. Baba et al., RIKEN Accel. Prog. Rep. 45, 9 (2012).
2) H. Baba et al., RIKEN Accel. Prog. Rep. 50, 224 (2017).
3) H. Baba et al., RIKEN Accel. Prog. Rep. 52, 146 (2019).
4) J. Zenihiro et al., in this report.

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Oﬄine measurement of mass and correlated decay properties using
radioactive 224 Ra source via MRTOF+α-TOF detector

Recently, we newly developed a detector called the “αTOF” detector1) for the measurement of mass and correlated decay properties by using a multi-reﬂection timeof-ﬂight mass spectrograph (MRTOF-MS).2) We performed realistic performance tests using a 224 Ra source.
The source, produced by a chemical separation from a
228
Th source,3) was placed in a cryogenic gas cell.
Ions of 220 Rn and 216 Po produced by the decay of224
Ra were thermalized in the gas cell and extractedusing an RF carpet, transported to the MRTOF-MS
preparation traps, and injected into the MRTOF-MS forthe correlated measurement of the time of ﬂight (ToF)and α-decay. 220 Rn and 216 Po have half-lives of 55.6 s
and 145 ms with characteristic α-particle energies of
6.29 MeV and 6.78 MeV, respectively. During this measurement, the MRTOF was operated for only 2 laps inside the MRTOF reﬂection chamber. This was suﬃcientto unambiguously determine the A/q value with a mass
resolving power of Rm ≈ 1500 with a wide mass bandwidth.

Counts / 12.8 ns

117
117

50
45
40
35
30
25
20
15
10
5
0
50
1110
45
40

35
30
25
20
15
10
5
01110
50

45
40
35
30
25
20
15
10
5
0
111.0
1110

118
118

119
119

A/q
120
120

singles ToF

216PoCO++

1120

1125

1130

1135

1115

1120

1125

1130

1135

111.5
1115

112.0
1120

112.5
1125

113.0
1130

113.5
1135

Po gated ToF

123
123

(a)

1115

Rn gated ToF

216

122
122

220RnHF++

220RnO++

220

121
121

CountsT. Niwase,∗1,∗2,∗3 M. Wada,∗3 P. Schury,∗3 H. Haba,∗2 S. Ishizawa,∗5,∗2,∗3 Y. Ito,∗4 D. Kaji,∗2 S. Kimura,∗2
H. Miyatake,∗3 K. Morimoto,∗2 K. Morita,∗1,∗2 M Rosenbusch,∗2 H. Wollnik,∗6 T. Shanley,∗7 and Y. Benari∗7

(b)

×10
1140

1140

3

10

(c)

×10

114.0
1140

3

Time-of-flight [μs]Fig. 1. (a) Singles ToF spectrum. (b) ToF spectrum in coincidence with 220 Rn α-decays obtained using a time gateof Tc = 180 s. (c) ToF spectrum in coincidence with 216 Po
decays with Tc = 450 ms.
∗1
∗2
∗3
∗4
∗5
∗6
∗7

decay time [s]Fig. 2. Distribution of decay time of 216 PoCO++ . The solidline indicates a distribution curve drawn with values obtained from the literature.

Figure 1 shows the ToF spectrum of 220 Rn and 216 Po.
ToF and α-decay signals were recorded event by eventwith absolute time stamps. Figure 1(a) shows the singles ToF spectrum. By using a coincidence time gate(Tc ) prior to the detection of an α-decay signal, it is possible to discriminate between ToF events corresponding
to 220 Rn and 216 Po, as shown in Fig. 1(b) and (c), respectively. To identify the peak of 216 Po, a ±150 keVenergy gate was used for the α-decay signal at approximately 6.78 MeV with Tc = 450 ms corresponding tothree half-life periods. To identify the peak of 220 Rn, asimilar gate was made on the 6.29 MeV α-decay signal
with Tc = 180 s.
Using the α-decay correlated ToF event, we determined that the ToF peak occurs at A/q = 118 and 120
from 220 Rn events and A/q = 122 from 216 Po events.
The limited mass resolution of the wide mass bandwidth measurement precluded precise molecular identiﬁcation. However, based on past experience, we havetentatively assigned the A/q = 118, 120 and 122 peaks to220
RnO++ , 220 RnHF++ and 216 PoCO++ , respectively.
In addition, by deﬁning the decay time as the time interval between the α-signal and the ToF event, we demonstrated the ability to measure half-lives with the α-TOF
detector. Figure 2 shows a plot of the measured decay
time of 216 PoCO++ ions along with the expected decay
time distribution function based on the value reported
in the literature. We evaluated the half-life of 216 Po as
T1/2 = 123(22) ms, which is in good agreement with theliterature value of 145(2) ms.
References

Department of Physics, Kyushu University
RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), KEK
Japan Atomic Energy Agency
Yamagata University
New Mexico State University
ETP Ion Detect

1) T. Niwase et al., Nucl. Instrum. Methods Phys. Res. A
953, 163198 (2020).
2) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B
335, 39(2014).
3) J. Narbutt et al., Appl. Radiat. Isot. 49, 89–91(1998).

- 14 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Oﬄine collinear laser spectroscopy of barium II toward measurement of
RIs at SLOWRI facility
M. Tajima,∗1 A. Takamine,∗1 Y. Sasaki,∗2,∗1 T. Asakawa,∗2,∗1 H. Iimura,∗3,∗1 M. Wada,∗4 H. A. Schuessler,∗5,∗1
Y. Matsuo,∗2,∗1 and H. Ueno∗1

∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Faculty of Science and Engineering, Hosei University
JAEA
Wako Nuclear Science Center, KEK
Department of Physics and Astronomy, Texas A&M University- 15 -

100000

138

Ba+

50000

137

Ba+

10000

Count rate of fluoresence signal [cps]The laser spectroscopy of atomic transitions is sensitive to nuclear structures in ground or metastablestates. In particular, the measurement of isotope shifts
and hyperﬁne splittings by collinear laser spectroscopy
has been a powerful tool to study RIs. Charge radii,
quadrupole deformation, and electromagnetic moments
have been elaborately measured at ISOL-type facilities
such as ISOLDE at CERN. However, the available nuclei are limited by chemical properties and lifetime with
the ISOL technique. On the other hand, the gas cell decelerator facility, SLOWRI,1) which is being developed
in RIKEN, will supply low-emittance and low-energy
RI beams including refractory elements and short-lived(≳10 ms) nuclei, which are diﬃcult to obtain from the
ISOL-type facility. We are preparing for collinear laser
spectroscopy by taking advantage of slow RI beams delivered from SLOWRI.
As a test of the system for collinear laser spectroscopy,
we performed the spectroscopy of barium ions. Barium was chosen because its ion production is relatively
easy and an existing dye laser is capable of inducing oneof the strong transitions, 5d 2 D5/2 -6p 2 P3/2 (614 nm).
A surface ionization source was constructed to obtain
Ba+ based on the design previously used at JAEA.2)
Barium oxide was heated up to approximately 2000 K
and a few nA of Ba+ were constantly produced. It was
extracted at 10.5 keV, focused by electrostatic lenses,
isotope-separated by a magnet, and focused again toenter an observation region. A continuous-wave (CW)dye laser (Coherent 899 Ring Laser) with Kiton Red
pumped by a solid-state laser (Verdi V10, 6 W) was irradiated collinearly with the Ba+ beam. The power was∼0.3 mW in the observation region. The laser wavelength was locked at 614.10433 nm by utilizing feedback
signals from a wavelength meter (HighFinesse WS-U10). The full width at half maximum (FWHM) of thelaser frequency was ∼5 MHz. In the observation region,
the velocity of ions was changed using a set of electrodes.
When the velocity was tuned according to the Doppler
shift, the ion was at resonance, and spontaneous emission from 6p 2 P3/2 to 6s 2 S1/2 (455 nm) successively occured. This ﬂuoresence signal was detected by a photomultiplier (Burle 8850). The quantum eﬃciency of thephotomultiplier was about 20% at 455 nm, but the efﬁciency was less than 1% at 614 nm. Therefore, this

5000

15000

136

Ba+

10000
5000

135

Ba+

6000
4000
2000

4000

134

Ba+

2000

900

1000

1100

1200

Scaning voltage [V]

1300

1400

Fig. 1. Resonance spectra for the isotopes 134–138 Ba+ showing the transition 5d 2 D5/2 -6p 2 P3/2 .

measurement is almost free of background counts due tostray laser light. Figure 1 shows the count rate of theﬂuoresence signal as a function of the voltage applied to
the Doppler-shift-tuning electrodes. Isotope shifts andhyperﬁne splittings for 135, 137 Ba+ with the nuclear spin
I = 3/2 were successfully observed.
Trajectory simulations suggest that the resonancespectrum becomes asymmetric due to misalignment of
the laser and ion beams, which can be a main systematic error. Detailed analysis is ongoing. We plan to introduce a ﬁne-tuning system of alignment before online
measurement.
References

1) M. Wada, Nucl. Instrum. Methods Phys. Res. B 317, 450(2013).
2) S. Ichikawa et al., Nucl. Instrum. Methods Phys. Res. A
274, 259 (1989).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Angle-tunable wedge degrader for an energy-degrading RI beamline†

The Optimized Energy-Degrading Optics (OEDO)
beamline1) was established at RIBF to produce 10–50MeV/nucleon beams by slowing down secondary beams
from the BigRIPS separator. This beamline can extend the energy range of RI beams that can be produced in RIBF to optimize nuclear reactions such as
nucleon transfer and Coulomb excitation.
The angle-tunable degrader, one of the key elementsin the OEDO beamline, is a monoenergetic degraderthat reduces the beam energy and spread of a beam.
It consists of two Al sheets with a quadratic cross section, the quadratic coeﬃcients of which have opposite
signs. While its central thickness is ﬁxed at 3 mm,
the wedge angle varies from 0 to 40 mrad according to
the relative positions of the two sheets. The eﬀective
area is ±30 mm (H) × ±50 mm (V), which is wide
enough for the typical beam width, ±20 mm. The average thickness deviations for sheets 1 and 2 are 33
and 58 µm, respectively. The total central thickness
can be increased by introducing an additional Al ﬂat
degrader immediately behind our system.
Figure 1 shows the whole system. For parallel andseparate movement of the sheets, the system includes
guides for the sheets, two parallel rails, and two linear
stepper motors. Each motor drives each Al sheet along
the corresponding rail. Because the motors operate
independently by remote control, we can optimize thewedge angle using real-time data.
Normalized CountJ. W. Hwang,∗1 S. Michimasa,∗1 S. Ota,∗1 M. Dozono,∗1 N. Imai,∗1 K. Yoshida,∗2 Y. Yanagisawa,∗2
K. Kusaka,∗2 M. Ohtake,∗2 D. S. Ahn,∗2 O. Beliuskina,∗1 N. Fukuda,∗2 C. Iwamoto,∗1 S. Kawase,∗3
K. Kawata,∗1 N. Kitamura,∗1 S. Masuoka,∗1 H. Otsu,∗2 H. Sakurai,∗2 P. Schrock,∗1 T. Sumikama,∗2
H. Suzuki,∗2 M. Takaki,∗1 H. Takeda,∗2 R. Tsunoda,∗1 K. Wimmer,∗4 K. Yako,∗1 and S. Shimoura∗1∗3∗4

FWHM =
5.4 MeV/u40

12.6 MeV/u

20
−20

−10

0

10

20

30

An experiment for evaluating the system performance was carried out at the OEDO beamline in RIBF.
A 171-MeV/nucleon 79 Se beam was produced by the
in-ﬂight ﬁssion of a 345-MeV/nucleon 238 U beam impinged on a 5-mm-thick Be target and was transported
to the OEDO beamline. The degrader system at thedispersive focus (FE9) in the OEDO beamline was optimized to obtain the 40-MeV/nucleon beam. The central thickness was set to 6 mm by placing a 3-mm-thick
ﬂat Al plate behind the system.
The performance of energy compression was evaluated by comparing the outgoing energy deviations using a monoenergetic degrader (the optimized wedge
angle) to a homogeneous degrader (0 mrad setting).
Figure 2 shows that the spread in the homogeneouscase is 12.6 MeV/nucleon in full width at half maximum (FWHM). The monoenergetic degrader reduced
the spread to 5.4 MeV/nucleon, which is similar to theestimated value of 5.2 MeV/nucleon. The performanceof the system was estimated as satisfactory and its ﬂexible wedge angle is useful to deal with many diﬀerent
nuclides and energies for various purposes.

Fig. 1. 3D design of the angle-tunable degrader system.

∗260

Fig. 2. Distributions of the outgoing energy spread using
a homogeneous and monoenergetic degrader. All distributions were normalized to have the same number of
events.



∗1

80

Outgoing Energy Deviation (MeV/u)


†Homogeneous
Monoenergetic

0
−30




100

Reference

Condensed from the article in Prog. Theor. Exp. Phys.
2019, 043D02 (2019), see also references therein
Center for Nuclear Study, the University of Tokyo
RIKEN Nishina Center
Department of Advanced Energy Engineering Science,
Kyushu University
Department of Physics, the University of Tokyo

1) S. Michimasa et al., Prog. Theor. Exp. Phys. 2019,
043D01 (2019).

- 16 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Eﬀects of columnar defects introduced by 2.6 GeV U-ion irradiation on
Jc characteristics of 2H-NbSe2
T. Tamegai,∗1 W. J. Li,∗1 S. Pyon,∗1 A. Takahashi,∗1 Y. Kobayashi,∗1 A. Yoshida,∗2 T. Kambara,∗2 andA. Ichinose∗3
One of the most salient features of superconductors
is the zero-resistance state. Although the presence ofsuch a state may be obvious in superconductors withouta magnetic ﬁeld, a motion of quantized vortices can destroy this useful state. The introduction of defects thatfunction as pinning centers for vortices is known to bea practical method to restore the ideal zero-resistancestate under strong magnetic ﬁelds, leading to the enhancement of the critical current density (Jc ) in superconductors. The irradiation of heavy ions on superconductors can create columnar defects (CDs) by destroying
the crystal structure of superconductors. CDs are ideal
pinning centers for vortices because they can trap vortices along their full length. The eﬀectiveness of CDs
in enhancing Jc was demonstrated in high-temperature
superconductors1) and also in iron-based superconductors.2) However, the eﬀect of heavy-ion irradiation onconventional superconductors has attracted much less attention to date. Only very recently, systematic work has
been conducted on 2H-NbSe2 irradiated at an angle of30◦ from the c-axis with a dose-equivalent matching ﬁeld
(BΦ ) of 3 T. In this paper, the presence of the peak eﬀectof Jc is reported. We investigated the eﬀect of 2.6 GeV
U-ion irradiation on the Jc characteristics of 2H-NbSe2 .
Single crystals of 2H-NbSe2 with Tc ∼ 7.2 K weregrown using the iodine transport method. 2.6 GeV U
ions were irradiated on 2H-NbSe2 at various angles, θCD ,from the c-axis and at various BΦ values up to 16 T. The
dependence of Jc on BΦ and θCD were studied.
Figure 1 shows scanning transmission electron microscope (STEM) image of 2H-NbSe2 irradiated by 2.6 GeV
U-ions from the directions of θCD = ±15◦ . It is clearthat continuous CDs with diameters of ∼7–10 nm werecreated.

100 nmFig. 1. Columnar defects created by 2.6 GeV U-ion irradiation ( θCD = ±15◦ ) in single-crystal 2H-NbSe2 .
∗1
∗2
∗3

Department of Applied Physics, The University of Tokyo
RIKEN Nishina Center
Central Research Institute of Electric Power Industry

Fig. 2. Eﬀects of 2.6 GeV U-ion irradiation on Jc -H in 2HNbSe2 : (a) pristine and irradiated samples with BΦ =1, 2, 4, and 6 T (//c) and (b) samples irradiated with
θCD = 0◦ , ±10◦ , ±20◦ , and ±30◦ at BΦ = 4 T.

Figure 2(a) shows Jc as a function of the magnetic
ﬁeld H(//c) at 4 K for a pristine sample of 2H-NbSe2
and samples irradiated at BΦ = 1, 2, 4, and 6 T along
the c-axis. In all cases, Jc decreases monotonically with
H. Compared with the pristine sample, Jc at 1 kOe
is enhanced by a factor of more than 10 even at BΦ =1 T. Figure 2(b) shows Jc as a function of H at 4 K
for 2H-NbSe2 irradiated from the directions of θCD =±10◦ , ±20◦ , or ±30◦ at BΦ = 2 T + 2 T Shown as areference is the sample with BΦ = 4 T at θCD = 0◦ . In
all cases, the magnetic ﬁeld H is applied along the c-axis(the average direction of CDs). It is remarkable that,in samples irradiated with θCD = ±10◦ and ±20◦ , Jc
shows a broad peak at H = 2–3 kOe, which is less than
10% of the total BΦ . Such a peak eﬀect is similar to theone observed in a sample with tilted CDs.3) It should
also be noted that similar broad peaks were observed in(Ba, K)Fe2 As2 irradiated at θCD ∼ ±15◦ . In this case,however, the peak appears at H ∼ 1/3BΦ . At a larger|θCD |, the broad peak is suppressed and replaced by a
sharp drop of Jc below H ∼ 0.3 kOe. The origin of thebroad peak in Jc -H in 2H-NbSe2 with splayed CDs is
not known yet. More systematic studies on 2H-NbSe2
with diﬀerent conﬁgurations of CDs are required.
References

1) L. Civale et al., Phys. Rev. Lett. 67, 648 (1991).
2) Y. Nakajima et al., Phys. Rev. B 80, 012510 (2009).
3) S. Eley et al., Sci. Rep. 8, 13162 (2018).
4) A. Park et al., Phys. Rev. B 97, 064516 (2018).

- 17 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Impurity eﬀects on magnetism of T⋆ -type La1−x/2 Eu1−x/2 Srx CuO4
M. Takahama,∗1 S. Asano,∗1 T. Taniguchi,∗1 I. Watanabe,∗2 and M. Fujita∗1
Since superconductivity in the cation-free T’-type
R2 CuO4 (R: rear-earth ion) was reported, the physical properties of cuprates have been studied in connection with the local structure around the CuO2 plane
and Cu coordination.1,2) However, owing to the diﬃculty in detecting the variation in oxygen states throughreduction annealing, the role of annealing in the mechanism of superconductivity and the genuine ground stateof T’-type cuprate remain controversial. To achieve
progress in these issues, we newly synthesized T⋆ -typeLa1−x/2 Eu1−x/2 Srx CuO4 (LESCO), which has a CuO5
pyramid coordination. For the T⋆ -type cuprate, it isconsidered that the oxygen defect in the as-sintered (AS)non-superconducting (SC) sample is repaired by oxidation annealing.3) Therefore, LESCO gives a unique
opportunity to study the eﬀect of local/global crystal
structure on the physical properties.
Our previous muon spin rotation/relaxation (µSR)
measurements on LESCO clariﬁed the existence of thedisordered magnetic state in the AS sample and theabsence of static magnetism in the oxidation-annealed(OA) SC sample, respectively.4) These results demonstrate a drastic change in the magnetic state due to annealing. To gain further insight into the ground stateof the T⋆ -type cuprate through the study of the magnetism, we investigated the impurity substitution eﬀect
for both AS and OA samples by µSR measurements.
For the experiments, we prepared a pelletized sampleof Zn- or Fe-substituted LESCO. The mixed powders
were ﬁred at 1050◦ C in air with intermediate groundings,
following which a part of poly-crystals was annealed under a high oxygen pressure of 400 atm at 500◦ C for 60 h.
Zero-ﬁeld µSR measurements were performed using aspectrometer installed at Port 2, RIKEN at Rutherford
Appleton Laboratory in the UK.
Figures 1(a) and (b) show representative zero-ﬁeldµSR time spectra. In both AS and OA samples of
La0.855 Eu0.855 Sr0.29 Cu0.95 Fe0.05 O4 , Gaussian-type depolarization changes into exponential-type depolarizing
upon cooling, and a fast depolarizing component appears at low temperatures, suggesting the developmentof electronic magnetic correlations. The onset temperature for the appearance of the fast depolarizing component (Tm ) was evaluated to be ∼22 K for the AS sample, which is higher than Tm of ∼7 K for the AS pristine
sample with the same hole concentration. Therefore,
the static (quasi-static) magnetism in the AS sample
is enhanced by the impurity substitution. From a systematic measurement, we found an increase in Tm withincreasing Fe concentration. Similarly, in the OA sample, the fast component develops below ∼12 K and the∗1∗2Institute for Materials Research, Tohoku University
RIKEN Nishina Center- 18 -

Fig. 1. The µSR time spectra for (a) as-sintered and (b)oxidation annealed La0.855 Eu0.855 Sr0.29 Cu0.95 Fe0.05 O4 .

volume fraction exceeds ∼60% at ∼3 K, indicating thatbulk static (quasi-static) magnetism is induced in the
OA sample by Fe substitution.
As for the Zn substitution eﬀect, similar results as in
AS Fe-substituted samples we observed, although theenhancement of Tm by Zn substitution is weak (Tm forthe 5% Zn-substituted AS x = 0.24 sample is ∼9 K).
However, no evidence of magnetic order was observedin the Zn substituted OA sample down to 2 K, whichis quantitatively the same as the result for the pristine OA sample. Thus, the stability of magnetism induced by magnetic and non-magnetic impurity is different; that is, the magnetic impurity more eﬀectively
stabilizes/induces the static magnetism in the T⋆ -type
cuprate. These results are consistent with the impurity
eﬀects reported for the optimally-doped and over-doped
La2−x Srx CuO4 , suggesting the universal nature of spincorrelations in hole-doped systems. As the next step, a
study of magnetic and SC properties in the under-doped
region, where a strong eﬀect of electron correlation canbe expected, is important.
References

1) M. Naito et al., Physica C 523, 28 (2016).
2) C. Weber et al., Nat. Phys. 6, 574 (2010).
3) J. Akimitsu et al., Jpn. J. Appl. Phys. 27, L1859 (1988).
4) S. Asano et al., J. Phys. Soc. Jpn. 88, 084709 (2019).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Size-dependent magnetic behavior of La2 CuO4 nanoparticles
S. Winarsih,∗1,∗2 F. Budiman,∗3,∗4 H. Tanaka,∗3,∗5 T. Goto,∗6 T. Adachi,∗6 B. Kurniawan,∗2 B. Soegijono,∗2 andI. Watanabe∗1,∗2
The study of high-Tc copper-oxide-based superconductors has been pursued for more than thirty years. The
magnetic ordering of the parent compound is strongly
inﬂuenced by element doping.1) The superconductivity(SC) appeared on increasing the hole-doping concentration.1) It was reported that weak magnetism appearedin the heavily doped regime for (x ≥ 0.30).2) Those results could provide valuable clariﬁcations of the magnetic
phase diagram of the high-Tc copper-oxide-based superconductors, but the correlation between spin dynamics
and SC remains unclear.
In the case of nanoparticles, Nèel predicted theoretically that ferromagnetic spins appear at the surface of
nanoparticles.3) This kind of magnetism was observedin nanogold systems and antiferromagnets such as CuO
and CoO.4,5) The nano-size eﬀect also caused a reduction in magnetic transition temperature, TN , of CuO.5)
In La2−x Srx CuO4 , Yin et al. reported possible weakmagnetism when the particle size was 113 nm with
0.1 ≤ x ≤ 0.30.6) With these results, the remaining problems on the magnetism and superconductivity of high-Tc
superconductors become more complicated.
We aim to investigate the nano-size eﬀect inLa2−x Srx CuO4 . We present the results of the parent
compound, La2 CuO4 (LCO). This report is an update
to our last year’s report.7) The sol-gel method was used
to produce the samples by controlling sintering temperatures and times to vary the particle size. We prepared
4 samples with diﬀerent particle sizes: 24 nm, 32 nm,
52 nm, and 71 nm. The detailed sample synthesis procedure was reported in our previous paper.8) Zero-ﬁeld(ZF) muon spin relaxation (µSR) measurements of thesesamples were performed at the RIKEN-RAL Muon Fa-

Fig. 2. Temperature dependence of the magnetic transition,
TN , of La2 CuO4 nanoparticles.

cility, Rutherford-Appleton Laboratory, UK, by using apulsed positive surface muon beam.
ZF-µSR time spectra of each sample were analyzed
using Eq. (1). Muon spin precession, which shows theappearance of a long-range magnetically ordered state,is expressed in the ﬁrst component. Slow relaxation ofmuon-spin polarization is expressed in the second component. From the ﬁtting results of the time spectra, we
could obtain the internal magnetic ﬁeld at the muon site,
Hint , which is shown in Fig. 1. The saturated Hint did
not change signiﬁcantly in all samples, showing a valueof about 420 G. This value is identical to that observedin bulk LCO.9)
A(t) = A1 e−λ1 t cos(ωt + ϕ) + A2 e−λ2 tFigure 2 depicts the temperature dependence of TN
which is deﬁned from Fig. 1. as the temperature whereHint suddenly drops to zero with increasing temperature.
The ﬁgure shows that TN decreases with reducing particle size. These results indicate that the particle sizeaﬀects TN without changing the saturated Hint . The result that the saturated d Hint value is the same between
nanoparticles of diﬀerent sizes and the bulk sample implies that the magnetic moments of Cu sensed by injectedmuons were almost the same. The reduction in TN might
be due to the destruction of the three-dimensional exchange interaction between the spins of Cu ions, which
existed in bulk LCO,10) as a result of reducing the particle size. We are now summarizing these results for submission to an international journal.
References

Fig. 1. Temperature dependence of the internal field at themuon site, d Hint , in La2 CuO4 nanoparticles.
∗1
∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Department of Physics, Universitas Indonesia
Department of Human Intelligence Systems, Kyushu Instituteof Technology
School of Electrical Engineering, Telkom University
Research Center for Neuromorphic AI Hardware, Kyushu Institute of Technology
Department of Engineering and Applied Sciences, Sophia University(1)1) T. P. Croft et al., Phys. Rev. B 89, 224513 (2014).
2) J. E. Sonier et al., Proc. Natl. Acad. Sci. USA 107, 17131(2010).
3) L. Nèel, Low Temperature Physics (Gordon and Breach,
New York, 1962), p. 413.
4) Y. Yamamoto et al., Phys. Rev. Lett. 93, 116801 (2004).
5) X. G. Zheng et al., Phys. Rev. B 72, 014464 (2005).
6) Y. Yin et al., J. Phys. Chem. C 117, 328 (2013).
7) S. Winarsih et al., RIKEN Accel. Prog. Rep. 52, 178 (2019).
8) S. Winarsih et al., Key. Eng. Mater. 966, 357 (2019).
9) J. I. Budnick et al., Europhys. Lett. 5, 651 (1988).
10) R. Coldea et al., Phys. Rev. Lett. 86, 5377 (2001).

- 19 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Targeted alpha therapy of thyroid cancer: Evaluation of [211 At]NaAt
treatment in the xenograft model†
T. Watabe,∗2,∗3 K. Kaneda-Nakashima,∗3,∗4 Y. Liu,∗2 Y. Shirakami,∗3 K. Ooe,∗1,∗2 A. Toyoshima,∗1,∗3
E. Shimosegawa,∗2 M. Fukuda,∗3,∗5 A. Shinohara,∗3,∗4 and J. Hatazawa∗3,∗5
Radioactive iodine has long been used clinically forpatients with diﬀerentiated thyroid cancer.1) 131 I is used
for the ablation of thyroid remnants or treatment ofmetastatic thyroid cancer.1) However, some patientswith multiple metastases are refractory to repetitive 131I
treatment, despite the targeted regions showing suﬃcient
iodine uptake.2) In such patients, beta-particle therapy
using 131 I is inadequate, and another strategy using amore eﬀective radionuclide targeting the sodium/iodide
symporter (NIS) is required.
211
At is an alpha emitter with chemical properties similar to those of iodine and is used in targeted alpha therapy. In the present study, we added ascorbic acid (AA)to 211 At solution to increase the radiochemical purity ofastatide and evaluated its eﬃcacy against diﬀerentiatedthyroid cancer, which is characterized by the expressionof NIS.
Methods
211
At was procured from the Research Center for Nuclear Physics at Osaka University and RIKEN via theshort-lived RI supply platform. Upon procurement,
211
At was separated and puriﬁed via dry distillation froma bismuth target and ﬁnally collected in distilled water.
Crude 211 At solution (AA(−) solution) and 211 At solution treated with AA (AA(+) solution) were prepared.
Thyroid uptakes were compared between the two solutions in normal male Wistar rats (n = 6). Cellular
uptake analysis in K1-NIS cells was performed underthe AA(+) and AA(−) conditions. The AA(+) solution was injected at three doses into K1-NIS xenograft
mice: 1 MBq (n = 6), 0.4 MBq (n = 6), and 0.1 MBq(n = 6). The vehicle was injected into control mice(n = 6). The treatment eﬀects were compared among
the four groups. Planar and SPECT images were acquired using a gamma camera system (E-cam, Siemens)with a low-energy all-purpose collimator.3) The energy
window was set at 79 keV ± 20%, targeting the X-rays
emitted from the daughter nuclide of 211 Po.4)
All the animal experiments were performed in compliance with the guidelines of the Institute of Experimental
Animal Sciences. The protocol was approved by the Animal Care and Use Committee of the Osaka University
Graduate School of Medicine.
Results
Thyroid uptake was signiﬁcantly enhanced in rats injected with the AA(+) solution as compared to those
†

∗1
∗2
∗3
∗4
∗5

Condensed from the article in J. Nucl. Med. 60, 1301, (2019)
RIKEN Nishina Center
Graduate School of Medicine, Osaka University
Institute for Radiation Sciences, Osaka University
Graduate School of Science, Osaka University
Research Center for Nuclear Physics, Osaka University

Fig. 1. (A) Planar and SPECT images of the mouse K1-NIS
xenograft model after the injection of the AA(+) solution.
High uptake was observed in the xenografts (arrows). (B)Change in the tumor size and body weight after the administration of AA(+) solutions.

injected with the AA(−) solution. Cellular uptake analysis showed a signiﬁcantly increased uptake of 211 At by
the K1-NIS cells under the AA(+) condition as comparedto the AA(−) condition. In the mouse xenograft model,
the K1-NIS tumors showed a signiﬁcant accumulation of211
At 3 and 24 h post administration (22.5 ± 10.4% ID
and 12.9 ± 6.8% ID, respectively). Tumor growth wasimmediately inhibited in a dose-dependent manner after
the administration of 211 At. In the survival analysis, the211
At groups (0.1, 0.4, and 1 MBq) showed signiﬁcantly
better survival than the control group.
Conclusion
The uptake of 211 At was enhanced in diﬀerentiatedthyroid cancer cells as well as normal thyroid by using
211
At solution treated with AA. The solution also showed
dose-dependent eﬃcacy against the K1-NIS xenografts,
suggesting its potential applicability to targeted alphatherapy.
References

1) T. Higashi et al., Ann. Nucl. Med. 26, 99 (2012).
2) M. Schlumberger, J. Endocrinol. Invest. 35, 40 (2012).
3) J. T. Kuikka et al., Nucl. Med. Commun. 19, 457 (1998).
4) E. L. Johnson et al., Nucl. Med. Biol. 22, 45 (1995).

- 20 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Live mouse imaging with 44m Sc by a multiple-isotope PET
T. Fukuchi,∗1 M. Shigeta,∗1 D. Mori,∗2 T. Yokokita,∗2 Y. Komori,∗2 H. Haba,∗2 and Y. Watanabe∗1
We have been developing a multiple-isotope positronemission tomography (MI-PET) system that can analyze the dynamics of multiple tracers. Using a positronγ emitter, which emits de-excitation γ-ray as a tracer
after the positron emission in β-decay, the MI-PET system identiﬁes the tracer by detecting the prompt γ-ray
emitted after the positron emission. Figure 1 shows aschematic illustration of the developed MI-PET prototype system. This system is composed of a PET scannerand additional γ-ray detectors.1) In this system, in addition to conventional PET imaging, coincidence among
the additional detectors and the PET scanner can be
performed. We expect that MI-PET will be used for
drug discovery research by direct comparison between
old and new drugs.
For multiple-isotope imaging using MI-PET, atleast one positron-γ emitter is necessary as a tracer.
Scandium-44 is one of the promising radioactive-tracer
candidates for MI-PET because of its large positronand γ-ray emission ratio and moderate half-life (44 Sc:
3.97 h, 44m Sc: 58.61 h). In our previous work, we
performed dual-isotope phantom imaging using 44m Sc
and 18 F (pure positron emitter) and evaluated the basic
imaging performance of MI-PET for 44m Sc.2)
Therefore, before the future development of a 44m Sclabeled drug for MI-PET applications, in order to test
the practical imaging ability of the MI-PET system for
44m
Sc, we conducted dual-isotope live mouse imaging
using 44m Sc, which is a simple substance.
Scandium-44m was produced at the RIKEN AVF cyclotron via the reaction 44 Ca(d, 2n)44m Sc with a 24MeV deuterium beam. As the irradiation target, 44 CaO

Fig. 2. Images of a live mouse with 44m Sc and 18 F-FDG injections (maximum intensity projection images). The reconstructed images were acquired with the absence (A)or presence (B) of γ-ray coincidence.

(97.0% enriched 44 Ca isotope) powder was pressed intoa disk of 10-mm diameter. The irradiated target wasdissolved in 6 M HCl and puriﬁed by the chemical processes.2) Finally, approximately 2 MBq of pure 44m Sc
was produced and transported to RIKEN Kobe campus
for the imaging experiment. Most of the short-lived byproduct, 44 Sc, decayed out during transportation.
In the mouse imaging experiment, 197 kBq 44m Sc(simple substance) and 198 kBq 18 F-FDG were administered to an 8-week-old normal male mouse by tail-vein
injection. Five minutes after administration, a 30-min
whole-body scan was performed under anesthesia.
The result of dual-isotope mouse imaging is shown in
Fig. 2. From the reconstructed images with the absence(A) or presence (B) of the prompt γ-ray detection, image(A) reﬂects the distribution of both 18 F-FDG and the
44m
Sc tracer, whereas image (B) reﬂects the isolated image of the 44m Sc tracer. In these images, we can clearlyobserve the diﬀerence between 18 F-FDG and 44m Sc distributions, i.e., 18 F-FDG is distributed in the heart andurinary bladder, whereas 44m Sc distributed in the liver.
From this experiment, we successfully demonstrated
the practical feasibility of dual-isotope imaging using
MI-PET with 44m Sc as the second tracer. In the future, we will synthesize a useful MI-PET drug labeledby 44m Sc and perform multiple-drug imaging on diseasemodel animals.
References

Fig. 1. Schematic illustration of the developed MI-PET prototype system.
∗1∗2

RIKEN Center for Biosystems Dynamics Research
RIKEN Nishina Center- 21 -

1) T. Fukuchi et al., Med. Phys. 44, 2257 (2017).
2) T. Fukuchi et al., RIKEN Accel. Prog. Rep. 52, 207(2019).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Production cross sections of ytterbium and thulium radioisotopes inalpha-induced nuclear reactions on natural erbium†
M. Saito,∗1,∗2 M. Aikawa,∗1,∗2,∗3 M. Sakaguchi,∗4,∗5,∗2 N. Ukon,∗6,∗2 Y. Komori,∗2 and H. Haba∗2

†
∗1
∗2
∗3
∗4
∗5
∗6

600

nat

Er(,x)500
Cross section (mb)Radionuclides are used in nuclear medicine for therapy and diagnosis. The production reactions of such
medical radionuclides should be investigated for practical use. The best route of their production can be
discussed based on cross sections of possible nuclear
reactions. The radionuclide 169 Yb (T1/2 = 32.018 d)
is a candidate of medical radionuclide. It decays withemission of Auger electrons and X-rays, which can beused for brachytherapy.1) There are several chargedparticle-induced reactions to produce 169 Yb. In thisstudy, we focused on alpha-induced reactions on nat Er.
Four previous studies of the nat Er(α, x)169 Yb reaction2–5) were found in a literature survey. However,
the experimental data published earlier are rather inconsistent with each other. Therefore, we measured
the excitation functions of the alpha-induced reaction
on nat Er. The cross sections of byproducts, 166 Yb, and165, 166, 167, 168, 170, 173
Tm, were also determined.
The experiment was performed at the RIKEN AVF
cyclotron. The stacked foil activation method andgamma-ray spectrometry were used. The stacked
target consisted of nat Er (99% purity, Goodfellow
Co., Ltd., UK) and nat Ti (99.6% purity, Nilaco
Corp., Japan). The nat Ti foils were used for thenatTi(α, x)51 Cr monitor reactions to assess beam parameters and target thicknesses. The sizes and weights
of both foils were measured to estimate their thicknesses. The derived thicknesses of nat Er and nat Ti were
20.06 mg/cm2 and 2.26 mg/cm2 , respectively. The
measured foils were cut to 10 × 10 mm2 to ﬁt a target holder. The target holder also served as a Faradaycup. The stacked target was irradiated for 1 hour witha 50.9-MeV alpha-beam. The energy was measured by
the time-of-ﬂight method.6) The energy degradation in
the stacked target was calculated using stopping powers obtained with the SRIM code.7) The beam intensity measured by the Faraday cup was 200.3 nA. Thesebeam parameters were assessed by the nat Ti(α, x)51 Cr
monitor reactions. According to the comparison, we
corrected the thickness of nat Er decreased by 1% within
the uncertainty.
The cross sections of the nat Er(α, x)169 Yb reaction

169

Yb

Homma 1980
Sonzogni 1992
Archenti 1985
Kiraly 2008
TENDL2017
This work

400
300
200
100
0

0

10

20

30

40

50

Energy (MeV)

Fig. 1. Excitation function of nat Er(α, x)169 Yb comparedwith previous data2–5) and TENDL-2017.9)

were derived. The radionuclide 169 Yb has a metastablestate with a short half-life (T1/2 = 46 s, IT: 100%),
which decays only to the ground state 169g Yb soonafter the irradiation. The 177.21-keV gamma (Iγ =22.28%) associated with the decay of 169g Yb was measured after a cooling time of 11 days. The cross sections were obtained from the net counts of the gamma
peak and are shown in Fig. 1. The results werecompared with those of previous studies2–5) and the
TENDL-2017 data.9) Both data of Király et al. (2008)
and TENDL-2017 have nearly the same peak positionas ours at approximately 35 MeV while the amplitudes
are diﬀerent. The other experimental data diﬀer signiﬁcantly from our results in both the shape and amplitude.
This work was supported by JSPS KAKENHI Grant
Number 17 K07004.
References

1) F. H. DeLand et al., J. Nucl. Med. 12, 683 (1971).
2) B. Király et al., Nucl. Instrum. Methods Phys. Res. B
266, 549 (2008).
3) A. A. Sonzogni et al., J. Radioanal. Nucl. Chem., Letters 165, 295 (1992).
4) A. Aechenti et al., Radiochemica Acta 38, 65 (1985).
5) Y. Homma et al., Int. J. Appl. Radiat. Isot. 31, 505(1980).
6) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566 (2014).
7) J. F. Ziegler et al., SRIM: the Stopping and Range ofIons in Matter, http://www.srim.org/ .
8) National Nuclear Data Center, The NuDat 2 database,
http://www.nndc.bnl.gov/nudat2/ .
9) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).

Condensed from the article in Appl. Radiat. Isot. 154,
108874 (2019)
Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
School of Science, Hokkaido University
Present address: Graduate School of Biomedical Science andEngineering, Hokkaido University
Advanced Clinical Research Center, Fukushima Medical
University- 22 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Production cross sections of dysprosium-159 radioisotope from thedeuteron-induced reactions on terbium-159 up to 24 MeV†
D. Ichinkhorloo,∗1,∗2,∗3 M. Aikawa,∗1,∗3,∗4 Ts. Zolbadral,∗4,∗2,∗3 Y. Komori,∗3 and H. Haba∗3
Dysprosium-159 (T1/2 = 144.4 d) can be used
to determine of bone mineral density.1) The dysprosium radionuclide can be produced by the chargedparticle-induced reactions on the monoisotopic element
terbium-159. In this work, the production cross sections of 157, 159 Dy and 160 Tb in the deuteron-induced
reactions on 159 Tb were studied. The results were compared with experimental data published previously2,3)
and TENDL-2017 data.4)
The experiment was performed at the RIKEN AVF
cyclotron. The stacked foil technique, the activation
method, and high-resolution γ-ray spectrometry wereused to determine the activation cross sections.
The stacked target consisted of 10 × 10 mm2 foils
cut from a large Tb foil (25 µmt, 25 × 50 mm2 , 99.9%
purity, Nilaco Corp., Japan) and two Ti foils (5 µmt,
50×100 mm2 , 99.6% purity and 20 µm, 120×100 mm2 ,
99.5% purity, Nilaco Corp., Japan). The sizes andweights of the large foils were measured to derive thethicknesses. The thicknesses of the Tb and two Ti foils
were found to be 20.56, 2.25, and 9.31 mg/cm2 , respectively. The Ti foils were interleaved to check the beam
parameters using the nat Ti(d, x)48 V monitor reaction.
The cut foils were stacked in a target holder, which
also served as a Faraday cup.
The deuteron beam was accelerated to 23.9 MeV using the RIKEN AVF cyclotron. The beam energy wasmeasured by the time-of-ﬂight method.5) The stacked
target was irradiated by the beam for 60 min withan average intensity of 94.3 nA. The beam intensity
was measured using the Faraday cup. Energy degradation in the stacked target was calculated using SRIM
code.6)The γ-rays emitted from the irradiated foils were
measured using a high-resolution high-purity germanium (HPGe) detector. The γ-ray spectra were analyzed using the software Gamma Studio (SEIKO
EG&G). The γ line at 58.0 keV (Iγ = 2.27%) emittedwith the 159 Dy decay (T1/2 = 144.4 d) was measured
to derive the cross sections of the 159 Tb(d, 2n)159 Dy
reaction. The measurements were performed after acooling time of 94 days. The γ line had negligible interference with the x-ray of the lead shielding of thedetector, which could be conﬁrmed by the absence ofpeaks at the energy in the two foils at the downstream
†
∗1
∗2
∗3
∗4

Fig. 1. Excitation function of the 159 Tb(d, 2n)159 Dy reaction.

of the beam. The self-absorption of the low-energy
γ line in the Tb foils was considered using the massattenuation coeﬃcient.
The cross sections derived from the corrected activities for 159 Dy production are presented with previous experimental data2,3) and TENDL-2017 data4) inFig. 1.
Our experimental data show a peak at approximately 14 MeV, which is consistent with other experimental data, while the amplitudes are substantialy
diﬀerent. The TENDL-2017 data slightly deviate fromours.
In summary, we performed an experiment to measure the excitation functions of deuteron-induced reactions on 159 Tb up to 24 MeV at the RIKEN AVF
cyclotron. The production cross sections of 157, 159 Dy
and 160 Tb were determined. The results were compared with previously obtained experimental data and
TENDL data.
This work was supported by JSPS KAKENHI Grant
Number 17K07004.
References
1) D. V. Rao et al., Med. Phys. 4, 109 (1977).
2) T. M. Duc et al., C. R. Acad. Sci. Ser. B 266, 100(1968).
3) F. Tárkányi et al., Nucl. Instrum. Methods Phys. Res.
B 316, 183 (2013).
4) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
5) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC 2014), 3566 (2014).
6) J. F. Ziegler et al., SRIM: the Stopping and Range ofIons in Matter, http://www.srim.org .

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 461, 102 (2019)
Faculty of Science, Hokkaido University
Nuclear Research Center, National University of Mongolia
Nishina Center for Accelerator-Based Science, RIKEN
Graduate School of Biomedical Science and Engineering,
Hokkaido University- 23 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Non-homologous end joining is the major repair pathway for DNA
double strand breaks in human fibroblast after heavy-ion irradiation
M. Izumi∗1 and T. Abe∗1
Accelerated heavy-ion particles with high linear energy transfer (LET) induce complex clustered DNA damage, which are diﬃcult to repair. Although the numbersof treatment facilities and patients undergoing heavyion therapy are increasing, the DNA repair mechanism
caused by heavy-ion irradiation is not fully understood at
the molecular level. DNA double-strand breaks (DSBs)
are the most lethal damage caused by ionizing irradiation and are repaired primarily by non-homologous end
joining (NHEJ) or homologous recombination (HR) in
mammalian cells, whereas alternative NHEJ (alt-NHEJ)
and/or single strand annealing (SSA) work only whenboth NHEJ and HR are impaired.
Several published results of survival assay using mammalian mutant cell lines deﬁcient in NHEJ or HR suggestthat NHEJ is inhibited after heavy-ion irradiation.1,2)
On the other hand, studies using inhibitors and CHO
mutant cell lines suggest that NHEJ is a major repair pathway after heavy-ion irradiation, although HR
is more important for higher-LET radiation.3,4) In addition, clustered DNA damage enhances end resection,
which promotes alt-NHEJ and/or SSA.5) Therefore, theDNA repair mechanism after heavy-ion irradiation is still
controversial in higher eukaryotes.
In this study, the DSB repair mechanism after heavyion irradiation was examined using speciﬁc inhibitors
against repair proteins. Human ﬁbroblast NB1RGB cells
were irradiated with X-ray, carbon ions, or argon ionsin the presence of an NHEJ inhibitor (NU7441) or HR
inhibitor (B02), as illustrated in Fig. 1. The repair eﬃciency was estimated by the kinetics of the phosphorylated histone H2AX foci, which reﬂect the presence of
DSBs (Fig. 2).
The number of phosphorylated histone H2AX after
X-ray irradiation decreased with similar kinetics in the
X-ray

40
20
1 35 8161) H. Wang et al., DNA Repair 7, 725 (2008).
2) S. C. Genet et al., Oncology Rep. 28, 1591 (2012).
3) H. Ma et al., Radiat. Oncol. 10, 225 (2015).
4) A. Gerelchuluun et al., Rad. Res. 183, 345–356 (2015).
5) H. Yajima et al., DNA Repair 12, 936 (2013).

24

time from irradiation (h)control
NU7441
B02

80
60
40
20
0

1 35 816

24

time from irradiation (h)Argon(LET = 300 keV/µm)
Number of phosphorylated-histone H2AX foci/cell (%)

600References

100

Number of phosphorylated-histone H2AX foci/cell (%)

Number of phosphorylated-histone H2AX foci/cell (%)

80

presence of NU7441 or B02, suggesting that both pathways work competitively and compensate each other. In
contrast, the foci formation after heavy-ion irradiation in
the presence of NU7441 was delayed and reached maximum 3 h after irradiation, probably because the histone H2AX is phosphorylated partly by DNA-PK. The
foci number decreased by 30% within 5 h of heavy-ion
irradiation with or without inhibitors. NU7441 inhibited DSB repair after heavy-ion irradiation at later time
points (5–24 h), whereas B02 had no eﬀect on DSB repair after heavy-ion irradiation. These results suggestthat high-LET radiation induced complex damage withdirty broken ends as well as simple repairable damage.
In addition, it is also suggested that NHEJ is the major repair pathway after heavy-ion irradiation and DNA
damage checkpoint delays the HR kinetics after heavyion irradiation.

Carbon(LET = 80 keV/µm)

control
NU7441(DNA-PKi)
B02(Rad51i)

100

Fig. 1. A: Schematic of the irradiation. Cells were tilted at
45 degrees for heavy-ion irradiation. B: Representative
immunostaining images of phosphorylated histone H2AX
(red) and nuclei (blue) after 2 Gy of X-ray or carbon-ion
irradiation. Arrows indicate the track of ions.

control
NU7441
B02

100
80
60
40
20
0

1 35 816

24

time from irradiation (h)Fig. 2. Time course of phosphorylated histone H2AX foci after irradiation. NB1RGB cells were pretreated with 3 µM NU7441 (DNA-PK inhibitor) or 10 µM B02 (Rad51 inhibitor) for 3 h and irradiatedwith 2 Gy of X-ray, carbon ions (LET = 80 keV/µm), or argon ions (LET = 300 keV/µm). The
percentage of foci per cell was plotted by normalizing the numbers at the maximum time point as100% after irradiation.
∗1

RIKEN Nishina Center- 24 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 53

Mutation analysis pipeline V2: an improved version of bioinformatics
pipeline for plant and microbial sequencing analysis
H. Ichida∗1 and T. Abe∗1
The rapid and coutinuous advancement in the massively parallel, “next generation” sequencing technology enabled a comprehensive analysis of genomic mutations in base-pair resolution in model species, suchas rice and Arabidopsis. A commonly used state-ofthe-art sequencing platform (HiSeq X, Illumina) produces roughly 2 terrabases of usable sequencing reads
per run in less than 3 days. To process, analyze, andextract usable information from such large datasets,a high-throughput bioinformatics pipeline that is specialized for mutation analysis and extensively utilizes
parallelization is required. Owing to such dataset volumes, it is not quite realistic to experimentally verify
all mutation candidates in each dataset, although themutation candidates must be accurate for such analysis. We have developed one such pipelines on the“HOKUSAI” parallel computing system, operated by
the Advanced Center for Computing and Communication, RIKEN in 2015;1) further, we have operated
and been adding continuous improvements since then.
Recently, there has been a great demand to support
various non-model organisms in the pipeline. Here,
we present a brief description of the major updated
version of our pipeline, namely, the mutation analysis
pipeline V2 (MAP-V2).
The basic workﬂow of MAP-V2 is essentially thesame as that of the previous version,2) but thepipeline’s internal structure and codes have been redesigned and re-written almost from scratch. MAPV2 runs quality checking of the input sequencing reads(by FastQC), mapping of the input sequencing reads
to the reference genome, and variant calling and ﬁltration to identify mutations induced in the genomes
and ﬁlter out false positives, which are mainly derived from intra-cultivar variations. In MAP-V2, raw
sequencing reads (supported for outputs from both
short- and long-read sequencers) are mapped to the reference genome sequences using one of the mapping programs supported by default (BWA, minimap2, ngmlr,
and BBMap), sorted, and realigned, and the data are
stored in the standard BAM format. Variant callings are performed with a maximum of twelve diﬀerent
programs (BcfTools, BedTools, BreakDancer, CNVNator, Delly, FreeBayes, GATK V4, GATK V3, Manta,
Pindel, Sniﬄes, and Strelka) and merged into a single ﬁle. The sequence quality check, mapping, andvariant calling statistics are summarized and compiled
in an HTML-format report for review. MAP-V2 utilizes a modular structure in each compartment of thepipeline: new programs, workﬂows, and therefore new
∗1

D

B
A

C

Fig. 1. An example of a MAP-V2 output. (A) Information
about the mutation, (B) evaluation, (C) the type andsize of the mutation, and (D) gene ID and annotationaﬀected by the mutation.

organisms can be easily added and integrated later. It
supports more programs than the previous version, but
this modular structure makes it easy to further extend
the pipeline to ﬁt speciﬁc requirements for each organism and project. MAP-V2 is currently implemented
and run on the HOKUSAI system, and it is capable oftransfer onto private and public cloud infractructurewith minor modiﬁcations, when necessary.
The most signiﬁcant change in MAP-V2 for users
is the output format of the results. An example ofa MAP-V2 output is shown in Fig. 1. MAP-V2 outRR
puts native (binary) Microsoft⃝ﬁles instead
Excel⃝of the tab-delimited text ﬁles in the previous version.
This change enabled the simulataneous output of multiple datasets in separate worksheets. A result ﬁlecontains three worksheets that include all post-ﬁlteredvariants identiﬁed from the mutants analysis, mutations that possibily cause the inactivation of gene functions based on prediction from gene structures and sequence changes (candidates of responsible mutations
in mutants), and statistics that summarizes identiﬁed
mutations categorize in mutation types. A variety offormatting options that visually categorize the possible
eﬀects of the identiﬁed mutations are used in MAP-V2
results.
References

1) H. Ichida et al., RIKEN Accel. Prog. Rep. 49, 254(2016).
2) H. Ichida et al., Plant J. 98, 301–314 (2019).

RIKEN Nishina Center- 25 -

II. RESEARCH ACTIVITIES I(Nuclear, Particle and Astro-Physics)

1. Nuclear Physics

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Decay studies in the region of 54 Zn
A. Kubiela,∗1 A. A. Ciemny,∗1 W. Dominik,∗1 A. Giska,∗1 Z. Janas,∗1 C. Mazzocchi,∗1 M. Pfützner,∗1
M. Pomorski,∗1 N. Soko φ̥ wska,∗1 R. Grzywacz,∗2 M. Madurga,∗2 C. Thornsberry,∗2 D. -S. Ahn,∗3 H. Baba,∗3
N. Fukuda,∗3 Y. Ichikawa,∗3 T. Kubo,∗3 B. Mauss,∗3 H. Nishibata,∗3 D. Suzuki,∗3 H. Suzuki,∗3 Y. Shimizu,∗3
M. Tajima,∗3 H. Takeda,∗3 A. Takamine,∗3 H. Ueno,∗3 H. Yamazaki,∗3 K. Yoshida,∗3 K. Kawata,∗4,∗3
Y. Takeuchi,∗5 A. Bezbakh,∗6 G. Kamiński,∗6 P. Szymkiewicz,∗6 A. Świercz,∗6 and Ł. Janiak∗7
In April 2019, we performed an experiment at the
RIBF facility to study the two-proton (2p) radioactivity of 54 Zn. The main goal was to measure correlations
between momenta of emitted protons in order to investigate whether they can provide insight into the structureof this exotic, extremely neutron-deﬁcient nucleus. In
particular, the comparison of the measured p − p correlations for 54 Zn with the previously established correlations for 45 Fe1) could reveal the expected inﬂuence ofthe proton Z = 28 shell closure on these proton dripline nuclei.
The nuclei of interest were produced using a 78 Kr
primary beam at 345 MeV/nucleon impinging on a
10 mm-thick beryllium target and separated with thehelp of the BigRIPS separator and ZeroDegree spectrometer.2) The separated ions, identiﬁed in-ﬂight, were
implanted into the Warsaw Optical Time Projection
Chamber (OTPC)3) mounted in the ﬁnal focal planeof the ZeroDegree spectrometer (F11). In order to increase the stopping eﬃciency in the relatively thin gasof the OTPC, a monoenergetic degrader was installedat the F10 focal plane.
The OTPC is a gaseous detector working in the TPC
mode, in which the signals are read out by means of optical methods instead of electronic ones. It can record
images of tracks of charged particles, allowing theiridentiﬁcation and the reconstruction of the decay eventsin three dimensions. The reconstruction is performedby combining the two-dimensional image recorded usinga CCD camera with the signal from a photomultiplierrecording the total light intensity as a function of time,
which is related to the position in the direction perpendicular to the image via the constant drift velocity. The
OTPC was ﬁlled with a gas mixture consisting of 69%
Ar, 29% He, and 2% CF4 at atmospheric pressure.
During the measurement, it was found that the production cross section for 54 Zn was smaller than thevalue predicted by the EPAX 3.1 empirical formula4) bya factor much larger than anticipated before the experiment. Nevertheless, decays of several ions of 54 Zn wererecorded, showing clear images of (2p) emission. An
example of such a decay is shown in Fig. 1(a). The de∗1
∗2
∗3
∗4
∗5
∗6
∗7

Fig. 1. Examples of CCD images showing decay events ofions stopped in the OTPC detector: (a) two-proton radioactivity of 54 Zn and (b) β-delayed two-proton emission from 55 Zn, illustrating the first observation of thischannel for this nucleus.

tailed analysis of the recorded (2p) events is currently inprogress. In addition, the collected data will be used todetermine the production cross section for 54 Zn, which
was previously unknown for the reaction used in thisexperiment. The cross-section systematics for neutrondeﬁcient zinc isotopes may shed light on the puzzle ofthe lower-than-expected production of 54 Zn. Understanding the fragmentation cross sections for nuclei atthe proton drip-line is of great importance for the upcoming next-generation radioactive beam facilities.
Before the ﬁnal setting on 54 Zn was tuned, other settings of BigRIPS were optimized and calibrated. This
allowed us to collect decay data for a few less-exotic nuclei in this region. According to a preliminary scan of
the recorded events, approximately 50 decays of 55 Cu,
380 decays of 56 Zn, and 300 decays of 55 Zn were observed. Among them, the latter case is the least known:
spectroscopic data for this nucleus are scarce.5) Amongthe decay events of this nucleus, we observed several
clear images of the β-delayed two-proton emission, achannel that has not been observed previously for thisnucleus. An example of such an event is shown in
Fig. 1(b). Careful analysis of all recorded decay eventsis in progress.
References

1) K. Miernik et al., Eur. Phys. J. A 42, 431 (2009).
2) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 03C003(2012).
3) M. Pomorski et al., Phys. Rev. C 90, 014311 (2014).
4) K. Sümmerer, Phys. Rev. C 86, 014601 (2012).
5) C. Dossat et al., Nucl. Phys. A 792, 18 (2007).

Faculty of Physics, University of Warsaw
Dep. of Physics and Astronomy, University of Tennessee
RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo
Department of Advanced Sciences, Hosei University
Joint Institute for Nuclear Research
National Centre for Nuclear Research- 27 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Study of the β-decay of 70 Kr
A. Vitéz-Sveiczer,∗1,∗2,∗3 A. Algora,∗1,∗2 A. I. Morales,∗1 B. Rubio,∗1 G. Kiss,∗2 J. Agramunt,∗1 V. Guadilla,∗1
A. Montaner-Pizá,∗1 S. E. A. Orrigo,∗1 A. Horváth,∗3 G. de Angelis,∗4 D. Napoli,∗4 F. Recchia,∗5 S. Lenzi,∗5
A. Boso,∗5 S. Nishimura,∗6 V. H. Phong,∗6 J. Wu,∗6 P. -A. Söderström,∗6 T. Sumikama,∗6 H. Suzuki,∗6
H. Takeda,∗6 D. S. Ahn,∗6 H. Baba,∗6 P. Doornebal,∗6 N. Fukuda,∗6 N. Inabe,∗6 T. Isobe,∗6 T. Kubo,∗6
S. Kubono,∗6 H. Sakurai,∗6 Y. Shimizu,∗6 C. Sidong,∗6 B. Blank,∗7 P. Ascher,∗7 M. Gerbaux,∗7 T. Goigoux,∗7
J. Giovinazzo,∗7 S. Grévy,∗7 T. Kurtukián Nieto,∗7 C. Magron,∗7 W. Gelletly,∗1,∗8 Zs. Dombrádi,∗7 Y. Fujita,∗9
M. Tanaka,∗9 P. Aguilera,∗10 F. Molina,∗10 J. Eberth,∗11 F. Diel,∗11 D. Lubos,∗12 C. Borcea,∗13
E. Ganioglu,∗14 D. Nishimura,∗15 H. Oikawa,∗15 Y. Takei,∗15 S. Yagi,∗15 W. Korten,∗16 G. de France,∗17
P. Davies,∗18 J. Liu,∗19 J. Lee,∗19 T. Lokotko,∗19 I. Kojouharov,∗20 N. Kurz,∗20 and H. Shaﬀner∗20
In this contribution, we present the preliminary results of the analysis of the experiment NP1112-RIBF93
related to our study of the β-decay of 70 Kr. The main
goal of the experiment was to study p-n pairing andisospin-related eﬀects in the structure of 70, 71 Kr using
their β-decays as a probe.
70
Kr nuclei were produced employing the fragmentation of a 78 Kr primary beam with an energy of
345 MeV/nucleon and average beam currents around40 pnA. The primary beam impinged on a 5 mm thick
Be target to produce a cocktail radioactive beam. The
nuclear species of interest were then separated and selected using the BigRIPS separator. The nuclei werethen implanted in the WAS3ABi active stopper, surrounded by the EURICA γ-ray spectrometer1) for the
study of their beta decay.
The level scheme of states in 70 Br populated in thebeta decay of 70 Kr has been deduced recently. Gammarays associated to the decay were identiﬁed using conventional β-γ and β-γ-γ coincidence techniques similarly to the procedure followed in Ref. 2). A primary
assignment of gamma rays was based on the determination of the half-lives obtained from implant-β-γ
correlations and their comparison with the half-life deduced from with implant-β correlations for the decay.
Then γ-γ coincidences and gamma intensities were employed to ﬁx their position in the decay level scheme.
Previous to our work, only the half-life of the decay

Fig. 1. Strongest identified gamma rays in the beta decayof 70 Kr. The spectrum is generated by requesting a
condition of gamma coincidences with beta transitions
correlated to 70 Kr implants in the analysis. Transitions
tagged with negative implant-β time correlations areshown in red.

was known with lower precision and no gamma rays
were associated to the decay.3) From the result of ouranalysis ﬁfteen gamma rays were identiﬁed for the ﬁrst
time and placed in the decay level scheme.4) In Fig. 1
we present the gamma spectrum generated in coincidence with beta transitions correlated to 70 Kr implants(in blue), that shows the most intense gamma rays.
Also for comparison, the gamma spectrum generated
in coincidence with background implant-beta correlations is given (in red). Presently, a comparison of theexperimental results with theoretical calculations5) is
performed in preparation for a publication.6)∗1

IFIC, CSIC-Univ. Valencia
MTA ATOMKI∗3 ELTE-Budapest∗4 INFN-Legnaro∗5 INFN-Padova∗6 RIKEN Nishina Center∗7 CEN Bordeaux-Gradignan∗8 Department of Physics, Surrey University∗9 Osaka University∗10 CCHEN∗11 Institute of Nucl. Physics, Universität zu Köln
∗12 Physik Department, Technische Universität München∗13 IFIN-HH, Bucarest∗14 Department of Physics, University of Istanbul∗15 Tokyo Univ. Sci.
∗16 IRFU, CEA, Universit Paris-Saclay∗17 GANIL-Caen∗18 Department of Physics, York University∗19 Department of Physics, University of Hong Kong
∗20 GSI, Germany∗2

References

1) S. Nishimura, Prog. Theor. Exp. Phys. 2012, 03C006(2012).
2) A. I. Morales et al., Phys. Rev. C 95, 064327 (2017).
3) G. Gürdal, E. A. Mccutchan, Nuclear Data Sheets 136,
1 (2016).
4) A. Vitéz-Sveiczer et al., Acta Phys. Polonica B 51, 587(2020).
5) P. Sarriguren, private communication.
6) A. Vitéz-Sveiczer et al., in preparation.

- 28 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Progress on the decay spectroscopy and measurement of half-lives andP n values in exotic nuclei near the N = 50 shell closure
C. J. Griﬃn,∗1 R. Caballero-Folch,∗1 L. Sexton,∗1,∗2 I. Dillmann,∗1 R. K. Grzywacz,∗3 K. P. Rykaczewski,∗4
J. L. Tain,∗5 J. Agramunt,∗5 A. Algora,∗5 H. Baba,∗6 S. Bae,∗7 N. T. Brewer,∗4 C. G Bruno,∗8 F. Calvino,∗9
T. Davinson,∗8 A. Estrade,∗10 S. Go,∗6 J. Ha,∗7 O. B. Hall,∗8 L. J. Harkness-Brennan,∗11 T. Isobe,∗6 D. Kahl,∗8
M. Karny,∗12 L. H. Khiem,∗13 G. G. Kiss,∗6 A. Korgul,∗12 S. Kubono,∗6 J. Liang,∗14 J. Liu,∗15 G. Lorusso,∗2,∗6,∗16
K. Matsui,∗6,∗17 K. Miernik,∗12 F. Montes,∗18 A. I. Morales,∗5 N. Nepal,∗3 S. Nishimura,∗6 V. H. Phong,∗6,∗19
B. C. Rasco,∗4,∗3 Y. Saito,∗1 D. W. Stracener,∗4 T. Sumikama,∗6 A. Tarifeño-Saldivia,∗9 A. Tolosa-Delgado,∗5
M. Wolinska-Cichocka,∗20 P. J. Woods,∗8 X. X. Xu,∗15 and R. Yokoyama∗3 for the BRIKEN Collaboration∗21
Total Fit
3

10

93

Se (Parent)93

Br ( daughter)
Br (n daughter)
Kr ( granddaughter)

92
93
92

Countsβ-delayed single- and multi-neutron emission is foundin neutron-rich nuclei in which β decay populates states
above the neutron separation energy (S n ) in the daughter nucleus. New generations of radioactive ion beamfacilities will be able to produce thousands of currently inaccessible neutron-rich nuclei. Delayed neutron emission is expected to be the dominant decay
process for these nuclei, with recent papers detailingthe importance of β-delayed neutron emission for ther -process.1,2)
In 2016, the BRIKEN collaboration constructed andcommissioned the world’s largest and most eﬃcient βdelayed neutron detector3,4) at RIBF to conduct a wideranging and systematic study into the decay propertiesof hundreds of the most exotic neutron-rich nuclei currently available. The BRIKEN detector consists of 140
3
He tubes within a HDPE moderator surrounding thehighly-segmented active stopper AIDA and two HPGeclover detectors in close geometry.
The NP1412-RIBF127R1 experiment implemented
the BRIKEN detector to measure β-delayed neutron
emission probabilities and half-lives, as well as conduct
decay spectroscopy studies, around the N = 50 shellclosure near the doubly-magic 78 Ni. This is a region
highlighted as sensitive to β-decay properties.5) In oneof the ﬁrst papers published from this experiment,6,7)
R. Yokoyama et al. observed two neutron emission in∗1

Physical Sciences Division, TRIUMF
Dept. of Physics, University of Surrey∗3 Dept. of Physics and Astronomy, University of Tennessee∗4 Oak Ridge National Laboratory∗5 Instituto de Física Corpuscular (IFIC)∗6 RIKEN Nishina Center∗7 Dept. of Physics and Astronomy, Seoul National University∗8 School of Physics and Astronomy, University of Edinburgh∗9 Universitat Politècnica de Catalunya (UPC)∗10 Dept. of Physics, Central Michigan University∗11 Dept. of Physics, University of Liverpool∗12 Faculty of Physics, University of Warsaw∗13 Institute of Physics, Vietnam Academy of Science and Technology∗14 Dept. of Physics and Astronomy, McMaster University∗15 Dept. of Physics, University of Hong Kong
∗16 National Physical Laboratory (NPL)∗17 Dept. of Physics, University of Tokyo∗18 National Superconducting Cyclotron Laboratory (NSCL),
Michigan State University∗19 Faculty of Physics, VNU University of Science∗20 Heavy Ion Laboratory, University of Warsaw∗21 www.wiki.ed.ac.uk/display/BRIKEN/Home∗2- 29 -Kr (-n / n- granddaughter)
Kr (n-n granddaughter)

91
93

102

92

Rb (-- great granddaughter)
Rb (--n / -n- / n-- great granddaughter)

10

-2000

0

2000

4000

6000

Implant -  correlation time (ms)

8000

10000

Fig. 1. Preliminary half-life analysis of 93 Se, showing thecontributions to the total fit from the parent and daughter isotopes.
84, 85, 87

Ga for the ﬁrst time, and detailed dominating
one-neutron emission from two-neutron unbound statesin 86, 87 Ga.
The analysis eﬀorts based at TRIUMF focus on the
91–95
Se and 94–97 Br isotopes. From these isotopes, halflives and P n values are expected to be measured for
92–95
Se and 95–97 Br for the ﬁrst time. An example decay
half-life Bateman ﬁt, considering the contributions to
the total ﬁt from each of the daughter nuclei along the
decay chain, is shown in Fig. 1. Decay spectroscopy
information in the neutron-rich region around A ∼ 90–
100 is sparse and this analysis will allow the extractionof the ﬁrst decay spectroscopy data for multiple nuclei
in this region.
Further analysis of the data is ongoing and expected
to yield multiple new P n values and half-lives. Early
publications highlight the potential of the highly eﬃcient BRIKEN detector to expand the systematics ofβ-decay in exotic neutron-rich nuclei, vital in developing accurate r -process nucleosynthesis models.
References

1) A. Arcones, F. Montes, Astrophys. J. 731, 5 (2011).
2) M. R. Mumpower et al., Phys. Rev. C 85, 045801 (2012).
3) A. Tarifeño-Saldivia et al., J. Instrum. 12, P04006 (2017).
4) A. Tolosa-Delgado et al., Nucl. Instrum. Methods Phys.
Res. A 925, 133 (2019).
5) T. Shafer et al., Phys. Rev. C 94, 055802 (2016).
6) B. C. Rasco et al., Nucl. Instrum. Methods Phys. Res.
A 911, 79 (2018).
7) R. Yokoyama et al., Phys. Rev. C 100, 031302(R) (2019).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Total absorption gamma spectroscopy studies around 100 Sn
A. Algora,∗1,∗2 J. A. Victoria,∗1 B. Rubio,∗1 J. L. Tain,∗1 A. Tolosa,∗1 J. Agramunt,∗1 E. Nacher,∗1
S. E. A. Orrigo,∗1 V. Guadilla,∗3 G. Kiss,∗2 D. Sohler,∗2 I. Kuti,∗2 T. Davinson,∗4 O. B. Hall,∗4 D. M. Kahl,∗4
C. G. Bruno,∗4 C. J. Appleton,∗4 P. J. Woods,∗4 S. Nishimura,∗5 N. Fukuda,∗5 H. Suzuki,∗5 D. S. Ahn,∗5
H. Baba,∗5 Y. Shimizu,∗5 H. Takeda,∗5 D. Nishimura,∗5 T. Isobe,∗5 M. Kaneko,∗5 S. Kubono,∗5 H. Sakurai,∗5
H. Shimizu,∗5 T. Sumikama,∗5 P. Doornenbal,∗5 M. L. Cortes,∗6 Zs. Podolyak,∗7 W. Gelletly,∗7 E. Ganioglu,∗8
Y. Fujita,∗9 F. Molina,∗10 J. Liu,∗11 J. Lee,∗11 K. P. Rykaczewski,∗12 M. Wolinska-Cichocka,∗13 M. Labiche,∗14
C. J. Griﬃn,∗15 S. Bae,∗16 J. Ha,∗16 and Y. Litvinov∗17
The region around 100 Sn in the nuclide chart is considered of great interest. There are several reasons for
that: the shell structure of nuclei in the vicinity of the
Z = N = 50 doubly-closed shell, the possibility of studying the heaviest accessible particle bound N = Z nucleus 100 Sn, the study of the quenching of the GamowTeller resonance1,2) and the astrophysical relevance of
decays in this region for the rapid proton-capture process (see3,4) and references therein).
Among the studied nuclei in the region, 100 Sn plays a
key role. The beta decay of this nucleus and that of nuclei located south east of 100 Sn is dominated by the single particle Gamow-Teller transition of πg9/2 → νg7/2 ,which is expected to be accesible inside the Qβ windowof the decay. This can provide a clear case for studying
the origin of the quenching of the Gamow-Teller strength(B(GT)), a topic that has attracted considerable attention over many years.1,2,5,6)
For these kind of studies it is mandatory to use a technique that provides beta decay data that do not suﬀer
from the Pandemonium eﬀect.7) This is the main motivation of the NP1612-RIBF147 experiment in which weused the total absorption spectrometer DTAS8) developed for DESPEC (FAIR) for measurements in combination with the implantation detector AIDA.9)
The beta decay of 100 Sn has been previously studied using high resolution experiments at GSI and at
RIKEN,10,11) showing that it has the largest B(GT)value measured in the nuclide chart. The limited statistics and the probable presence of a low-energy gamma
ray not identiﬁed in previous experiments constrain thereliability of the determination of the excitation energyof the 1+ state in 100 In, the state that should be mainly∗1

IFIC, CSIC-Univ. Valencia
MTA ATOMKI∗3 SUBATECH∗4 School of Physics and Astronomy, University of Edinburgh∗5 RIKEN Nishina Center∗6 INFN-Legnaro∗7 Department of Physics, Surrey University∗8 Department of Physics, University of Istanbul∗9 Osaka University∗10 CCHEN∗11 Department of Physics, University of Hong Kong
∗12 Oak Ridge National Laboratory∗13 Heavy Ion Laboratory, Warsaw University∗14 STFC Daresbury Laboratory∗15 Physical Sciences Division, TRIUMF∗16 Dept. of Physics and Astronomy, Seoul National University∗17 GSI∗2- 30 -

Fig. 1. Particle ID in BigRIPS from the experiment.

populated in the beta decay of 100 Sn. The excitationenergy of this state, as well as the β end-point energyof this transition is crucial for the determination of theB(GT) value. The high eﬃciency of DTAS and its granularity can contribute to solve this question as shown byMonte Carlo simulations. In this experiment we will
also have access to exotic decays that were not previously studied with the total absorption technique at theMass Separator (MSEP) at GSI because of the limited
production. In Fig. 1 we show the particle identiﬁcation in BigRIPS obtained during our experiment. Dueto technical problems we were able to run only 4 days
from a total of 10 approved days. The continuation of
the experiment is expected in 2020. The analysis of thepartial set of data is on going.
References

1) I. Hamamoto et al., Phys. Rev. C 48, R960 (1993).
2) B. Alex Brown et al., Phys. Rev. C 50, R2270 (1994).
3) T. Faestermann et al., Prog. Part. Nucl. Phys. 69, 85(2013).
4) P. Sarriguren, Phys. Rev. C 83, 025801 (2011).
5) P. Gysbers et al., Nat. Phys. 15, 428 (2019).
6) L. Batist et al., Eur. Phys. J. A 46, 45 (2010).
7) J. C. Hardy et al., Phys. Lett. B 71, 307 (1977).
8) J. L. Tain et al., Nucl. Instrum. Methods Phys. Res. A
803, 36 (2015).
9) C. J. Griﬃn et al., Proc. XIII Nuclei in the Cosmos 1,(Debrecen, Hungary, 2014) p. 97.
10) C. B. Hinke et al., Nature 486, 341 (2012).
11) D. Lubos et al., Phys. Rev. Lett. 122, 222502 (2019).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

New and comprehensive β- and βp-decay spectroscopy results in thevicinity of 100 Sn†
J. Park,∗1 R. Krücken,∗2 D. Lubos,∗3 R. Gernhäuser,∗3 M. Lewitowicz,∗4 S. Nishimura,∗5 and H. Sakurai∗6 forthe EURICA Collaboration
15

†
∗1
∗2
∗3
∗4
∗5
∗6

QEC or Ex (MeV)

The doubly magic nucleus 100 Sn and other nuclei
with similar mass and atomic numbers possess various
nuclear structure and astrophysical properties of importance.1) It is one of the few regions in the nuclear
chart where experimental observables to be comparedto nuclear shell model (SM) and ab-initio theories were
scarce, due to the low production cross section. However, a high radioactive isotope beam production rate
at RIBF enabled a decay spectroscopy experiment on
100
Sn and other N ≈ Z ≈ 50 nuclei, which featured
WAS3ABi2) and EURICA3) detectors for heavy ion
implantation, charged particle decay correlation and
γ-ray spectroscopy.
The database on β-decay and βp-decay half-lives(T1/2 ) and branching ratios (bβ , bβp ) of these protonrich nuclei was greatly expanded, with new or more
precise values. Several nuclei and isomers experienced
notable revisions on their T1/2 and bβp . β-decay endpoint measurements yielded ground-state to groundstate energy diﬀerences for 8 proton-rich nuclei, as
well as the excitation energies of 3 isomeric states (seeFig. 1). The results were consistent with AME2016,4)
mass models and SM calculations. Energy spectraof βp decays were produced with new, comparable orhigher statistics in relation to the available literature.
From EURICA data, 25 new γ rays were observed
and assigned to 10 new states in multiple nuclei, withguidance from empirical SM5) in the (p1/2 , g9/2 ) protonand neutron orbitals above the 76 Sr core. One example is the β-decay and βp decay of 98m In, where theﬁrst observation of βp-delayed γ rays from this isomer
could be assigned to excited states in 97 Cd (see Fig. 2).
As for 97 Cd itself, a new isomer with J π = (1/2− )was proposed based on a new β-delayed γ ray with
Eγ = 1245 keV, whose associated β-decay half-life was
0.73(7) s.
A systematic evaluation of the assignment of new excited states to tentative spins and parities was carriedout by comparing the energies of the corresponding
states, between their experimental and theoretical values. The energy discrepancies were less than 300 keV
and/or 20% relative to the experimental excitation energy.

10

EXP
DZ33
HB
KTUY05

5

0

90

Rh

92

Pd

AME/NUBASE16
FRDM12
HFB27
SLGM
93

Pd

94

Ag 95Ag
Isotope

97m
96m

96

Cd

Cd

Cd

97

Cd

98m

In

98

In

1290

511

70

763

Fig. 1. Ground-state to ground-state energy diﬀerencesand excitation energies of isomers deduced from β-decay
endpoint energy measurements. The reader is advised
to refer to the original article for references of the different mass models and SM calculations.

50

291

40

10
0
0

200

400

730

20

1417

30
602

Counts / 2 keV

60

600
800
E (keV)

1000

1200

1400

Fig. 2. γ-ray spectrum with EURICA, correlated to theβp decay of 98m In. Except for the 511-keV annihilation
γ ray, the peaks labeled in black correspond to known
γ rays in 97 Cd. Those labeled in blue were assigned asde-excitation transitions from new excited states in thesame nucleus.

References
1) T. Faestermann, M. Górska, H. Grawe, Prog. Part.
Nucl. Phys. 69, 85 (2013).
2) S. Nishimura, Prog. Theor. Exp. Phys. 2012, 03C006(2012).
3) P. -A. Söderström et al., Nucl. Instrum. Methods Phys.
Res. B 317, 649 (2013).
4) M. Wang et al., Chin. Phys. C 41, 030003 (2017).
5) F. J. D. Serduke, R. D. Lawson, D. H. Gloeckner, Nucl.
Phys. A 256, 45 (1976).

Condensed from the article in Phys. Rev. C 99, 034313(2019)
Department of Physics, Lund University
TRIUMF
Physik Department, Technische Universität München
Grand Accélérateur National d’Ions Lourds (GANIL)RIKEN Nishina Center
Department of Physics, University of Tokyo- 31 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Improved value for the Gamow-Teller strength of the 100 Sn beta-decay†
D. Lubos,∗1,∗2 J. Park,∗3 T. Faestermann,∗1 R. Gernhäuser,∗1 R. Krücken,∗4 M. Lewitowicz,∗5 S. Nishimura,∗2
and H. Sakurai∗6 for the EURICA collaboration
The main aim of experiment NP0702-RIBF09 was toimprove the value for the Gamow-Teller strength of the100
Sn beta-decay. This is important because 100 Sn is
the heaviest self-conjugate doubly-magic nucleus. The
data have now been evaluated and published.
With about 2500 nuclei the number of detected
100
Sn nuclei was about ten times higher than in previous experiments and new isotopic species towards the
proton dripline were discovered at the RIKEN Nishina
Center.1)
Decay spectroscopy has been performed with thehigh-eﬃciency detector arrays WAS3ABi and EURICA. The half-life of 100 Sn was measured more precisely than the literature values2) using two methods:a) β-decays correlated with identiﬁed mother nuclei
and b) correlated β-decays were in coincidence one of
the known γ-rays following the beta-decay was observed. Both results agreed yielding an average ofT1/2 = 1.18 ± 0.08 s. This value agrees with and has
about half the error compared to the average of theprevious values.
Similarly, the β-decay endpoint energy was determined for two data sets, the β-spectrum after a 100 Sn
implantation and by requiring, in addition, a γ-ray
from the decay. The method was tested by analyzing also the 98 Cd decay Q-value. Both 100 Sn data
sets yielded consistent results which give as average
Qβ = 3.91 ± 0.15 MeV. This value is more precise andlarger than the best previous result2) by about twice
the summed error bars. This discrepancy may be due
to unaccounted systematic uncertainties in either measurement.
The value and the uncertainty of the resulting
strength for the pure 0+ → 1+ Gamow-Teller decay
is improved to BGT = 4.4+0.9−0.7 . In Fig. 1 we compare anumber of theoretical calculations of BGT with experimental values: an extrapolation of the BGT -values of
the heavier even-even Sn isotopes (the error bar seems
too small) and the values measured in the two previous
experiments at GSI. Of all theories the chiral eﬀective
ﬁeld theory seems to describe the data best.

†
∗1
∗2
∗3
∗4
∗5
∗6

Fig. 1. Comparison of experimental and predicted GTtransition strengths of 100 Sn. The theoretical values
on the left side are from: Extreme Shell Model,3)
Shell Model - Monte Carlo,4) Finite Fermi Systems andQuasiparticle Random Phase Approximation,5) Large
Scale Shell Model with transitions to the four and one
lowest 1+ -states,2) the range of recent work explaining
GT-quenching with calculations using Eﬀective Field
Theory combined with 2-Body Currents.6) Experimental values are: an extrapolation from heavier even Snisotopes,7) ﬁrst8) and second2) GSI experiment, thepresent result and the average of all available experimental data. For the weighted average of Qβ its error
has been inﬂated by a factor 1.8 to account for the toolarge χ2 .

References

1) I. Celikovic et al., Phys. Rev. Lett. 116, 162501 (2016).
2) C. B. Hinke et al., Nature 486, 341 (2012), and Suppl.
Info.
3) A. de Shalit, I. Talmi, Nuclear Shell Theory (Aca- demic
Press, New York and London, 1963).
4) D. Dean, S. Koonin, T. Kuo, K. Langanke, P. Radha,Phys. Lett. B 367, 17 (1996).
5) A. Bobyk, W. Kaminski, Acta Phys. Pol. B 31, 953(2000).
6) P. Gysbers et al., Nature Phys. 15, 428 (2019).
7) L. Batist et al., Eur. Phys. J. A 46, 45 (2010).
8) T. Faestermann et al., Eur. Phys. J. A 15, 185 (2002).

Condensed from the article in Phys. Rev. Lett. 122, 222502(2019)
Technische Universität München
RIKEN Nishina Center
Lund University
TRIUMFGANIL, CEA/DSM-CNRS/IN2P3
University of Tokyo- 32 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

β-delayed neutron emission probabilities for understanding theformation of the r-process rare-earth abundance peak (REP)
G. G. Kiss,∗1 A. Tarifeño-Saldivia,∗2 J. L. Tain,∗3 A. Estrade,∗4 S. Nishimura,∗5 J. Agramunt,∗3 A. Algora,∗3
N. T. Brewer,∗6 R. Caballero-Folch,∗7 F. Calvino,∗2 T. Davinson,∗8 I. Dillmann,∗7 N. Fukuda,∗5
R. K. Grzywacz,∗9 O. Hall,∗6 A. I. Morales,∗3 A. Navarro,∗2 N. Nepal,∗5 B. C. Rasco,∗6 K. P. Rykaczewski,∗6
N. T. Szegedi,∗1 A. Vitéz-Sveiczer,∗1 A. Tolosa-Delgado,∗3 P. Vi,∗10 R. Yokoyama,∗9 M. Wolinska-Cichocka,∗11
and P. Woods∗8 for the BRIKEN collaboration∗12
The abundance distribution of the rapid-neutron
capture (so-called r-) process is characterized by twolarge maxima at masses of A ∼ 130 and A ∼ 195,
which are related to the ﬂow of matter through theneutron shell closures at N = 82 and N = 126.
However, there is an additional, relatively small—but
distinct—peak around A ∼ 160, which corresponds
to the region of the rare-earth elements. In contrast to the main abundance maxima that form during
the (n, γ) ↔ (γ, n) equilibrium, the rare-earth abundance peak (REP) originates later, after neutron exhaustion, thus representing a unique opportunity to
study the late-time environmental conditions of the rprocess.1–3) Several diﬀerent peak-production mechanisms were suggested, but experimental data—masses,
β-decay parameters, and neutron capture rates—areclearly needed to evaluate the diﬀerent astrophysicalscenarios. The most inﬂuential nuclei to the REP formation, located in the A ∼ 160, 55 ≤ Z ≤ 64 neutronrich region, have been identiﬁed by sensitivity studies.3)
The aim of the NP1612-RIBF148 experimental program is to measure the β-decay parameters, halflives, and delayed-neutron-emission probabilities (Pnvalues) of these species using the BRIKEN array,
which is the largest and most eﬃcient β-delayed neutron detector built.4,5) It consists of 140 3 He gasﬁlled proportional counters embedded in a high-density
polyethylene moderator. The neutron detector andtwo CLARION-type clover high purity germanium detectors are placed around the AIDA DSSSD array6)
which contains six layers of highly segmented Si detectors for the detection of implantations and β electrons.
The study was conducted at the Radioactive Isotope Beam Factory. A 60-pnA intensity 238 U beam

Fig. 1. Preliminary half-life analysis for 163 Pm isotopes,
showing the contributions to the total ﬁt from the parent, daughter, and granddaughter isotopes. Our T1/2
result is compared to the existing data7) (bold andslanted characters, respectively).

was accelerated up to an energy of 345 MeV/nucleon
before incidence on a 4-mm thick Be target to produce
radioactive secondary beams by in-ﬂight ﬁssion. The
nuclei of interest were separated and identiﬁed in the
BigRIPS spectrometer, transported through the ZeroDregree spectrometer, and implanted in the AIDA
array. Figure 1 shows the results of the preliminary
half-life analysis of the 163 Pm isotope. Although somehalf-lives in this region have already been already measured7) our experiment will not only provide a large
number of new Pn values8) and half-lives but also considerably improve the precision of the available data.
References

1) R. Surman et al., Phys. Rev. Lett. 79, 1809 (1997).
2) A. Arcones, G. Martinez Pinedo, Phys. Rev. C 83,
045809 (2011).
3) R. M. Mumpower et al., Prog. Part. Nucl. Phys. 86, 86(2016).
4) A. Tarifeno-Saldivia et al., J. Instrum. 12, P04006 (2016).
5) A. Tolosa-Delgado et al., Nucl. Instrum. Methods Phys.
Res. 925, 133 (2019).
6) C. Griﬃn et al., Proc. Sci. NIC-XIII, 097 (2014).
7) J. Wu et al., Phys. Rev. Lett. 118, 072701 (2017).
8) A. Tarifeño-Saldivia et al., RIKEN Accel. Prog. Rep.
52, 39 (2019).

∗1

Institute for Nuclear Research (Atomki)∗2 Universitat Politècnica de Catalunya (UPC)∗3 Instituto de Física Corpuscular (IFIC)∗4 University College of Science and Engineering, Central
Michigan University (CMU)∗5 RIKEN Nishina Center∗6 Oak Ridge National Laboratory∗7 Physical Sciences Division, TRIUMF∗8 School of Physics and Astronomy, University of Edinburgh∗9 Department of Physics and Astronomy, University of Tennessee∗10 Faculty of Physics, VNU University of Science∗11 HIL, University of Warsaw∗12 www.wiki.edu.ac.uk/display/BRIKEN/Home- 33 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Evolution of collectivity and mirror symmetry along N = Z
K. Wimmer,∗1,∗2 T. Hüyük,∗1 F. Browne,∗3 P. Doornenbal,∗3 T. Koiwai,∗2,∗3 H. Sakurai,∗2,∗3 T. Arici,∗4
M. Bentley,∗5 M. L. Cortés,∗6 N. Imai,∗7 A. Jungclaus,∗1 N. Kitamura,∗7 S. Lenzi,∗8,∗6 B. Longfellow,∗9
R. Lozeva,∗10 B. Mauss,∗3 D. Napoli,∗6 M. Niikura,∗2 X. Pereira-Lopez,∗5 F. Recchia,∗8,∗6 P. Ruotsalainen,∗11
R. Taniuchi,∗2,∗3 S. Uthayakumaar,∗5 V. Vaquero,∗1 R. Wadsworth,∗5 and R. Yajzey∗5,∗12
BigRIPS PID

Unlike any other physical system the nucleus represents a unique dual quantum many-body system. Itsconstituents, the protons and neutrons, are assumed
to be identical, except for their electric charge. They
can be seen as two representations of the nucleon, withisospin components tz = ±1/2 for neutrons and protons, respectively. Under the assumption of charge independence of the strong interaction, hence invarianceunder rotation in the isospin space, the properties ofmirror nuclei should be identical.
Mirror symmetry is typically studied through energy
diﬀerences between excited states of mirror nuclei or+
isospin triplets. Measurements of B(E2; 0+
gs → 21 )values for T = 1 isospin triplets allow to extract information on the proton and neutron matrix elements andto test isospin symmetry.1) The proton and neutron
multipole matrix elements can be written in isospin
representation

32

30

103

61

Ga
62

Zn

28

102

63

Z

Cu
64

Ni

26

10

24

22
2

2.02

2.04

2.06

2.08

2.1
A/Q

2.12

2.14

2.16

2.18

2.2

ZDS PID
34

103

32
30
28
102

26

(1)

Z

1
Mn/p = (M0 (Tz ) ± M1 (Tz ))
2

24
22

where M0 (Tz ) is the isoscalar and M1 (Tz ) the isovector multipole matrix element. Assuming isospin conservation the proton matrix elements of isobars area linear function of Tz only, i.e. M0 (Tz ) = M0 and
M1 (Tz ) = M1 · Tz , with constant M0/1 for all Tz . The
linearity provides a direct test of the isospin purity ofthe states. So far this has been tested for light nuclei, mostly in the sd shell, the heaviest case where+
the B(E2; 0+
gs → 21 ) values of all three members aremeasured is the A = 46 system.2)
In order to test this relation in heavier nuclei we havestudied the Coulomb excitation of A = 62 nuclei. All
three nuclei were studied under identical experimental conditions to reduce the statistical and theoreticaluncertainties. The 62 Zn, 62 Ga, and 62 Ge beams were
produced by the fragmentation of a 345 AMeV primary78
Kr beam provided by the SRC. Unique particle identiﬁcation in BigRIPS and the ZeroDegree Spectrome-

20

10

18
16
2

2.02

2.04

2.06

2.08

2.1

2.12

2.14

2.16

2.18

2.2

A/Q

Fig. 1. Particle identification plots for the 62 Zn beam impinging on the Be target.

ter was achieved by means of ∆E-Bρ-TOF measurements. Secondary Be and Au targets were used to+determine the B(E2; 0+
gs → 21 ) values. The particle
62
identiﬁcation plots for the Zn beam impinging on the
Be target is shown in Fig. 1.
The beams impinged on secondary targets located at
the F8 focus. γ rays from excited states were detectedin the DALI2+ array. Suﬃcient statistics for all threemembers of the A = 62 multiplet were collected todetermine the linearity of the proton multipole matrix
elements with a precision of about 5%. Additionally
new states were observed in nuclei beyond the N = Z
line. The results will shed new light on the evolutionof collectivity along the N = Z line and provide one of
the most stringent tests of isospin symmetry.

∗1

IEM-CSIC
Department of Physics, The University of Tokyo∗3 RIKEN Nishina Center∗4 GSI Helmholtzzentrum für Schwerionenforschung∗5 Department of Physics, University of York
∗6 INFN-Laboratori Nazionali di Legnaro∗7 Center for Nuclear Study, The University of Tokyo∗8 Department of Physics, University of Padova∗9 NSCL, Michigan State University∗10 CSNSM, Université Paris-Sud∗11 Department of Physics, University of Jyväskylä∗12 Physics Department, Jazan University∗2

References

1) A. M. Bernstein, V. R. Brown, V. A. Madsen, Phys.
Rev. Lett. 42, 425 (1979).
2) A. Boso et al., Phys. Lett. B 797, 134835 (2019).

- 34 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

First attempt at in-beam γ-ray spectroscopy of 100 Sn
S. Chen,∗1 J. Lee,∗1 A. Corsi,∗2 K. Wimmer,∗3 P. Doornenbal,∗4 F. Browne,∗4 M. L. Cortés,∗5 T. Koiwai,∗3,∗4
H. Sakurai,∗3,∗4 A. Algora,∗6 D. Brugnara,∗5,∗7 J. Cederkäll,∗8 J. Gerl,∗9 M. Górska,∗9 G. Haefner,∗10
K. Kokubun,∗3 P. Koseoglou,∗11,∗9 S. Kubono,∗4 P. Li,∗1 P. Liang,∗1 J. Liu,∗1 Z. Liu,∗12 T. Lokotko,∗1 J. Park,∗8
L. G. Sarmiento,∗8 R. Taniuchi,∗4,∗13 W. Xian,∗1 and I. Zanon∗5
ZeroDegree PID

BigRIPS PID

52

52
105

101

51

Sn 102Sn

100

105

Sn

51

104
104

103

49

50
103

Z

50

Z

The study of the heaviest self-conjugate exotic doubly magic nucleus 100 Sn and the single-particle natureof its neighboring nuclei are of great importance to thefundamental understanding of nuclear structure andthe astrophysical rp-process path. Owing to the low
production rate, no spectroscopic information, except
β-decay, has been measured for 100 Sn so far. As one of
the ﬁrst observables for nuclear structure, we aim at
the measurement of the ﬁrst 2+ state of 100 Sn, whichindicates the strength of the N = Z = 50 shell closures. A proposal was made to populate the excitedstates from neutron-removal reations of heavier Sn isotopes to perform an in-beam γ-ray spectroscopy measurement.1) In order to properly estimate the beamtime required, the production cross sections for 100 Sn
through secondary fragmentation reactions need to be
known. We performed an experiment with a beamtime of 4 days to measure the production cross sections of 100 Sn produced in neutron-removal reations
from 101, 102 Sn.
A 124 Xe primary beam at 345 MeV/nucleon was provided by SRC with an average intensity of ∼140 pnA.
The beam impinged on a 5-mm-thick 9 Be target to produce radioactive beams containing neutron-deﬁcient
Sn isotopes with the BigRIPS separator. It was tuned
to center on 101 Sn nuclei while accepting 102 Sn simultaneously. Average beam intensities in front of the secondary targets were 2 pps and 27.5 pps for 101, 102 Sn.
A 5-mm-thick CH2 target and a 3-mm-thick C target were used to induce the 1n- and 2n-removal reactions of 101, 102 Sn on C and H. The beam particles and reaction products were identiﬁed with the
BigRIPS and ZeroDegree spectrometers, respectively,
via the measurements of Bρ, ∆E, and ToF on an
event-by-event basis. The beam energies were measured to be ∼173 MeV/nucleon in BigRIPS and only
∼98 MeV/nucleon in ZeroDegree. The DALI2+ higheﬃciency γ-detection array2) was employed to detect

49
102

102

48

48
10

10

47

47
1.96 1.98 2 2.02 2.04 2.06 2.08 2.1

1

1.96 1.98 2 2.02 2.04 2.06 2.08 2.1

A/Q

1

A/Q

Fig. 1. BigRIPS particle identification (left) and ZeroDegree particle identification (right). The isotopes
101, 102
Sn are selected in BigRIPS, while 100 Sn is selected in ZeroDegree.
Table 1. Number of identified events and rates.
5 mm CH2−1n: 101 Sn→ 100 Sn50+ 53 (1.3/h)−2n: 102 Sn→ 100 Sn50+ 42 (1.0/h)

3 mm C40 (1.0/h)
30 (0.8/h)

the γ rays emitted in ﬂight from reaction products inthe vicinity of 100 Sn.
The particle identiﬁcation plots of BigRIPS and ZeroDegree are shown in Fig. 1. Data were accumulated
for 41 h on a CH2 target and 38 h on a C target.
The total numbers and counting rates of fully stripped100
Sn produced by 1n- and 2n-removal reactions are
summarized in Table 1.
The cross sections on the C target were determinedfrom the number of incident projectiles, the number ofreaction products identiﬁed in ZeroDegree, the atom
number in the target, as well as the ZeroDegree transmission and acceptance measured in the same setting.
The cross sections on H were determined using thedata with the CH2 target, subtracting the contribution measured on the C target, after normalization. To
maximize the statistics, hydrogen-like charge states of100
Sn in the ZeroDegree were considered to be usedin 1n-removal reactions. Preliminary values for crosssections have been obtained. Several new γ transitions
were also observed in this region. Detailed analyses forcross sections and γ spectroscopy are ongoing.

∗1

Department of Physics, The University of Hong Kong
IRFU, CEA, Université Paris-Saclay∗3 Department of Physics, University of Tokyo∗4 RIKEN Nishina Center∗5 INFN-LNL∗6 IFIC Valencia∗7 University of Padova∗8 Department of Physics, Lund University∗9 GSI Helmholtzzentrum Darmstadt∗10 Universté Paris-Saclay, CNRS/IN2P3, IJCLab∗11 Institut für Kernphysik, Technische Universität Darmstadt∗12 Institute of Modern Physics, Chinese Academy of Sciences∗13 Department of Physics, University of York
∗2

References

1) J. Lee, A. Corsi, K. Wimmer, RIKEN Proposal (2016).
2) S. Takeuchi et al., Nucl. Instrum. Methods Phys. Res.
A 763, 596 (2014).

- 35 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Intermediate-energy Coulomb excitation of 102 Sn

Being presumably the heaviest, particle-bound, doubly magic N = Z nucleus, 100 Sn oﬀers a fundamental
testing ground for nuclear theories. Experimental signatures of shell structure can be provided by the 2+
1
energies as well as by the reduced transition probabil+ities, B(E2; 0+
gs → 21 ). In the Sn isotopes between
the N = 50 and N = 82 shell closures, the 2+
1 energies are well established and show an almost constant value,1) as expected in the generalized seniority
scheme. Within the same framework, the B(E2)↑ values should resemble an inverted parabola peaking at
mid-shell. However, measurements in the most protonrich Sn isotopes,2–4) have shown a clear deviation fromthe expected behavior.
Diﬀerent calculations based on the large-scale shellmodel as well as on the relativistic quasi-particle
random-phase approximation have been performed inorder to give an account of the measured B(E2)↑ values.5) Although the calculations tend to agree on theneutron-rich side of the chain, signiﬁcant diﬀerences
are observed on the proton-rich side. This is particularly true for 102 Sn, where the diﬀerence between thepredictions amounts to almost a factor of 3, making
this isotope a good candidate for the investigation of
the eﬀects driving the nuclear structure in the vicinity of 100 Sn. In order to elucidate the nuclear structure underlying the measured B(E2)↑ values, the ﬁrst
Coulomb excitation measurement of 102 Sn was performed at the RIBF.6)
A 345 MeV/nucleon beam of 124 Xe with an average intensity of 120 pnA was fragmented on a 5 mm
thick Be target at the entrance of the BigRIPS separator7) to produce 102 Sn. Within the same experimental setting, 100 Cd was also transmitted. The isotopes
of interest were identiﬁed on an event-by-event basis using the Bρ-∆E-Bρ technique. Figure 1a) shows
the particle identiﬁcation obtained in BigRIPS, where102
Sn and 100 Cd are clearly visible. A 0.5 mm Au
target placed at F8 was used to induce Coulomb ex-

Atomic number

M. L. Cortés,∗1,∗2 F. Browne,∗2 P. Doornenbal,∗2 S. Chen,∗3 A. Corsi,∗4 T. Koiwai,∗5,∗2 J. Lee,∗3
H. Sakurai,∗2,∗5 K. Wimmer,∗5 A. Algora,∗6 D. Brugnara,∗1 J. Cederkäll,∗7 J. Gerl,∗8 M. Gorska,∗8
G. Haefner,∗9 K. Kokubun,∗5 P. Koseoglou,∗10 S. Kubono,∗2 P. Li,∗3 P. Liang,∗3 J. Liu,∗3 Z. Liu,∗11
T. Lokotko,∗3 J. Park,∗7 L. G. Sarmiento,∗7 R. Taniuchi,∗12 W. Xian,∗3 and I. Zanon∗1
51
50
102

49 102Sn

Sn

48
47

100
100

Cd
Cd

100
100
Cd

Cd

46
a)

45

b)

2.04 2.06 2.08 2.10 2.12 2.14
Mass-to-Charge ratio

2.04 2.06 2.08 2.10 2.12 2.14
Mass-to-Charge ratio

Fig. 1. Particle identification in a) BigRIPS, and b) Zerodegree. In both cases 102 Sn and 100 Cd are clearly identified.

citation. In addition, measurements with a 3 mm C
target were performed to obtain the nuclear contribution to the cross section. Outgoing fragments wereidentiﬁed using the ZeroDegree spectrometer, as shownin Fig. 1b). The target was surrounded by the higheﬃciency DALI2+ γ-detector array, composed of 226
NaI(Tl) detectors.8,9) The average beam intensities before the secondary target were 90 pps and 4200 pps for102
Sn and 100 Cd, respectively, with an energy around
177 MeV/nucleon.
As part of the experiment, the incoming beam was
implanted into a plastic target at F7 for 1 h, and dataon the γ rays emitted following the decay of the isomerwere collected using a HPGe detector. By combining
the information on the number of ions implanted andthe total γ rays observed, the isomeric ratio of thebeam can be obtained. This quantity is fundamental
for the correct determination of the cross section fromthe Coulomb excitation measurement. Finalization of
the outgoing particle identiﬁcation and further analysis
on the in-beam γ-ray spectra of 102 Sn and 100 Cd is
ongoing.
References∗1

INFN-Laboratori Nazionali di Legnaro
RIKEN Nishina Center∗3 Department of Physics, The University of Hong Kong
∗4 IRFU, CEA, Université Paris-Saclay∗5 Department of Physics, The University of Tokyo∗6 IFIC Valencia∗7 Department of Physics, Lund University∗8 GSI Helmholtzzentrum für Schwerionenforschung∗9 Université Paris-Saclay, CNRS/IN2P3, IJCLab∗10 Institut für Kernphysik, Technische Universität Darmstadt∗11 Institute of Modern Physics, Chinese Academy of Sciences∗12 Department of physics, University of York1) http://www.nndc.bnl.gov/ensdf/ .
2) G. Guastalla et al., Phys. Rev. Lett. 110, 172501 (2013).
3) V. M. Bader et al., Phys. Rev. C 88, 051301(R) (2013).
4) P. Doornenbal et al., Phys. Rev. C 90, 061302(R) (2014).
5) T. Togashi et al., Phys. Rev. Lett. 121, 062501 (2018).
6) M. L. Cortés, Experiment NP1612-RIBF153R1.
7) T. Kubo, et al., Prog. Theor. Exp. Phys. 2012 (2012).
8) S. Takeuchi et al., Nucl. Instrum. Methods Phys. Res.
A 763, 596 (2014).
9) I. Murray et al., RIKEN Accel. Prog. Rep. 51, 158 (2017).

∗2- 36 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

In-beam γ-ray spectroscopy of 136 Te at relativistic energies†
V. Vaquero,∗1 A. Jungclaus,∗1 P. Doornenbal,∗2 K. Wimmer,∗3,∗2 A. M. Moro,∗4 K. Ogata,∗5 T. Furumoto,∗6
S. Chen,∗2,∗7 E. Nácher,∗1 E. Sahin,∗8 Y. Shiga,∗9 D. Steppenbeck,∗2 R. Taniuchi,∗2,∗3 Z. Y. Xu,∗10 T. Ando,∗3
H. Baba,∗2 F. L. Bello Garrote,∗8 S. Franchoo,∗11 K. Hadynska-Klek,∗8 A. Kusoglu,∗12,∗13 J. Liu,∗10
T. Lokotko,∗10 S. Momiyama,∗3 T. Motobayashi,∗2 S. Nagamine,∗3 N. Nakatsuka,∗14 M. Niikura,∗3
R. Orlandi,∗15 T. Saito,∗3 H. Sakurai,∗2,∗3 P. A. Söderström,∗2 G. M. Tveten,∗8 Zs. Vajta,∗16 andM. Yalcinkaya∗120.25
B(E2;0+ → 2+) e2b2+
The reduced transition probability B(E2; 0+
1 → 21 )+to the ﬁrst excited 2 state of the neutron-rich nucleus 136 Te, with two protons and two neutrons outside the doubly-magic 132 Sn core, has been measured
via Coulomb excitation at relativistic energies at the
RIKEN Radioactive Isotope Beam Factory. A value ofB(E2) = 0.191(26) e2 b2 was extracted from the measured inelastic scattering cross section on a Au target taking into account the contributions from both
Coulomb and nuclear excitations. This value is compared to previous experimental results reported in theliterature and various theoretical calculations in Fig. 1.
Our measurement, performed at relativistic energies,
agrees with the large value which has recently been obtained in Coulomb excitation at safe energies at Oak
Ridge.1) It is, however, in conﬂict with the low-energy
Coulomb excitation measurement of Refs. 2–3) and thepreliminary result of the experiment using the fast timing technique reported by Fraile et al.4) For a detailed
discussion of the comparison to theory we refer thereader to the original publication.
The high statistics gathered in the present experiment allowed for the ﬁrst time to evaluate in detailthe validity of the approach employed in the analysis
of Coulomb excitation experiments at beam energies
around 150 MeV/nucleon and to estimate the systematic uncertainties involved in the diﬀerent steps of theanalysis. In this publication, a detailed discussion of
the analysis procedure is provided so that it can serve
as guideline for the analysis of future experiments using the same technique but accumulating less statistics. In particular, the correct determination of the

0.2

0.15
0.1

SM 1
SM 2

0.05

QRPA
MCSM
QRPA2
NSM

0

SM 3

132

This work
J. M. Allmond et al. 2017
A. E. Stuchbery et al. 2013
Danchev et al. 2011
L. M. Fraile et al. 2008
C. J. Barton et al. 2003

134
136
Mass Number (A)+Fig. 1. Comparison of the experimental B(E2; 0+
1 → 21 )136
value forTe determined in the present work to literature values for the 132, 134, 136 Te isotopes and diﬀerent
theoretical calculations (for details see the original publication).

exclusive scattering cross section to the 2+
1 state, taking into account the scattering-angle dependent losses
due to the limited acceptance of the ZeroDegree spectrometer and losses due to reactions which take place
on any material in the beam line between the identiﬁcations in BigRIPS and the ZeroDegree spectrometer,
is discussed in detail. The other important part of
the analysis concerns the determination of a B(E2)value from the measured exclusive cross section, which
requires a consistent description of both nuclear andelectromagnetic excitations. In the present case, thecode FRESCO5,6) was employed for this purpose.

Condensed from the article in Phys. Rev. C 99, 034306(2019)∗1 IEM-CSIC Madrid∗2 RIKEN Nishina Center∗3 Department of Physics, University of Tokyo∗4 Universidad de Sevilla, Sevilla∗5 Research Center for Nuclear Physics, Osaka University∗6 Graduate School of Education, Yokohama National University∗7 Peking University, Bejing∗8 University of Oslo, Oslo
∗9 Department of Physics, Rikkyo University∗10 University of Hong Kong
∗11 IN2P3-CNRS, Orsay∗12 Istanbul University, Istanbul∗13 ELI-NP, Magurele∗14 Department of Physics, Kyoto University∗15 Advanced Science Research Center, JAEA, Tokai∗16 MTA Atomki, Debrecen†

References

1) J. M. Allmond et al., Phys. Rev. Lett. 118, 092503(2017).
2) D. C. Radford et al., Phys. Rev. Lett. 88, 222501 (2002).
3) M. Danchev et al., Phys. Rev. C 84, 061306(R) (2011).
4) L. M. Fraile et al., Nucl. Phys. A 805, 218 (2008).
5) I. J. Thompson, Comput. Phys. Rep. 7, 3 (1988).
6) http://fresco.org.uk .

- 37 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Study of Gamow-Teller transitions from 11 Li

The studies of dynamic properties of exotic nuclei suchas giant resonances, which are manifested at high excitation energies (>10–15 MeV), are in the very earlystage. No data are available on spin-isospin collectivity
for nuclei with large isospin asymmetry factors, where(N − Z)/A > 0.25.1)
In the SAMURAI30 experiment, we studied themost basic nuclear collectivity, the Gamow-Teller (GT)
giant resonance, in the drip-line nucleus 11 Li at
181 MeV/nucleon. The charge-exchange (CE) (p, n) reactions in inverse kinematics are eﬃcient tools to extract
the B(GT) strengths of unstable isotopes up to high excitation energies, without Q-value limitation.2)
The combined setup of Particle Analyzer Neutron
Detector Of Real-time Acquisition (PANDORA)3) lowenergy neutron counter and the SAMURAI magnetic
spectrometer,4) together with a thick liquid hydrogentarget allowed us to perform such measurements withhigh luminosity. In this setup, PANDORA is used forthe detection of the recoil neutrons. The neutron kinetic
energies are deduced by the time-of-ﬂight technique, andSAMURAI is used for tagging the decay channel of thereaction residues. Many relevant decay channels after
the CE reaction can be measured in a single magnetic
rigidity setting owing to the large acceptance of SAMURAI. Such a setup was already successfully used in our
ﬁrst (p, n) experiment on 132 Sn.5) It was proven that we
can obtain information about the strength distributionof isovector spin-ﬂip giant resonances of unstable nuclei
with quality comparable to those on stable nuclei.5)∗1

Center for Nuclear Study, University of Tokyo, JapanRIKEN Nishina Center, Japan∗3 School of Physics, Peking University, China∗4 Department of Physics, Kyushu University, Japan∗5 Horia Hulubei Nat. Inst. of Phys. and Nucl. Eng., Romania∗6 Inst. de Physique Nuclaire, Univ. Paris-Saclay, France∗7 Department of Physics, Rikkyo University, Japan∗8 LPC CAEN, France∗9 Department of Physics, Ewha Womans University, Korea∗10 ATOMKI, Institute for Nuclear Research, HAS, Hungary∗11 Department of Physics, Toho University, Japan∗12 KVI - CART, University of Groningen, The Netherlands∗13 GSI Helmholtzzentrum für Schwerionenforschung, Germany∗14 Department of Physics, Korea University, Korea∗15 Department of Physics, Tohoku University, Japan∗16 Dept. of Physics, Tokyo Institute of Technology, Japan∗17 Department of Physics, University of Tokyo, Japan∗18 Dépt. Physique Nucl., CEA, Univ. Paris-Saclay, France∗19 Dept. of Physics, Saitama University, Saitama, Japan∗20 Institute of Modern Physics, Chinese Acad. of Sci., China∗2Counts [arb. units]

L. Stuhl,∗1,∗2,∗10 M. Sasano,∗2 J. Gao,∗2,∗3 Y. Hirai,∗4 K. Yako,∗1 T. Wakasa,∗4 D. S. Ahn,∗2 H. Baba,∗2
A. I. Chilug,∗5,∗2 S. Franchoo,∗6 Y. Fujino,∗7 J. Gibelin,∗8 I. S. Hahn,∗9 Z. Halász,∗10 T. Harada,∗11
M. N. Harakeh,∗12,∗13 D. Inomoto,∗4 T. Isobe,∗2 H. Kasahara,∗4 D. Kim,∗14 G. G. Kiss,∗10 T. Kobayashi,∗15
Y. Kondo,∗16 Z. Korkulu,∗2,∗10 S. Koyama,∗17 Y. Kubota,∗2 A. Kurihara,∗16 H. N. Liu,∗18 M. Matsumoto,∗16
S. Michimasa,∗1 H. Miki,∗16 M. Miwa,∗19 T. Motobayashi,∗2 T. Nakamura,∗16 M. Nishimura,∗2 H. Otsu,∗2
V. Panin,∗2 S. Park,∗9 A. T. Saito,∗16 H. Sakai,∗2 H. Sato,∗2 T. Shimada,∗16 Y. Shimizu,∗2 S. Shimoura,∗1
A. Spiridon,∗5 I. C. Stefanescu,∗5 X. Sun,∗2,∗3 Y. L. Sun,∗18 H. Suzuki,∗2 Y. Togano,∗7 T. Tomai,∗16,∗2
L. Trache,∗5 D. Tudor,∗5,∗2 T. Uesaka,∗2 H. Yamada,∗16 M. Yasuda,∗16 K. Yoneda,∗2 K. Yoshida,∗2 J. Zenihiro,∗2
and N. Zhang∗20,∗1
θC.M.=4º — 6º

li

Pre

ry

na
mi

Ex(11Be) [MeV]Fig. 1. Preliminary excitation energy spectrum in the 4◦ –6◦ center-of-mass system. The contributions of diﬀerent
decay channels are presented.

In our 11 Li(p, n)11 Be measurement, we successfully
identiﬁed clear kinematical correlations6) between theneutron energy and laboratory scattering angle for thediﬀerent decay channels of 11 Be: 10 Be+n, 9 Be+2n,
α+6 He+n, 2α+3n, 8 Li+t, and 9 Li+d.
The reconstruction of the excitation-energy spectrum
up to about 40 MeV, including the giant resonance region, is ongoing. Figure 1 presents preliminary resultsof the excitation energy spectra in the daughter nucleus
11
Be. The background subtraction and correction for thedetection eﬃciency and acceptance are ongoing. We will
derive the excitation energy spectra for θC.M. = 1◦ –10◦
from all decay channels. The forward scattering peaksin the 0◦ –8◦ center-of-mass system, suggest a strong GTtransition at approximately 18 MeV, in agreement withprevious beta-decay studies.7)
References

1) K. Nakayama et al., Phys. Lett. B 114, 217(1982).
2) M. Sasano et al., Phys. Rev. Lett. 107, 202501 (2011).
3) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A 866,
164 (2017).
4) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
5) J. Yasuda et al., Phys. Rev. Lett. 121, 132501 (2018).
6) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. B 463,
189 (2020).
7) R. Raabe et al., Phys. Rev. Lett. 101, 212501 (2008).

- 38 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Structure of 13 Be probed via quasi-free scattering
A. Corsi,∗1 Y. Kubota,∗2,3 G. Authelet,∗1 H. Baba,∗2 C. Caesar,∗4 D. Calvet,∗1 A. Delbart,∗1 M. Dozono,∗3
J. Feng,∗5 F. Flavigny,∗6 J.-M. Gheller,∗1 J. Gibelin,∗7 A. Giganon,∗1 A. Gillibert,∗1 K. Hasegawa,∗8,∗2 T. Isobe,∗2
Y. Kanaya,∗9,∗2 S. Kawakami,∗9,∗2 D. Kim,∗10,∗2 Y. Kiyokawa,∗3 M. Kobayashi,∗3 N. Kobayashi,∗11
T. Kobayashi,∗8,∗2 Y. Kondo,∗12,∗2 Z. Korkulu,∗2 S. Koyama,∗11,∗2 V. Lapoux,∗1,∗2 Y. Maeda,∗9 F. M. Marqués,∗7
T. Motobayashi,∗2 T. Miyazaki,∗11 T. Nakamura,∗12,∗2 N. Nakatsuka,∗14,∗2 Y. Nishio,∗15,∗2 A. Obertelli,∗3,∗2
A. Ohkura,∗15,∗2 N. A. Orr,∗7 S. Ota,∗3 H. Otsu,∗2 T. Ozaki,∗12,∗2 V. Panin,∗2 S. Paschalis,∗4 E. C. Pollacco,∗1
S. Reichert,∗16 J.-Y. Roussé,∗1 A. T. Saito,∗12,∗2 S. Sakaguchi,∗15,∗2 M. Sako,∗2 C. Santamaria,∗1,∗2 M. Sasano,∗2
H. Sato,∗2 M. Shikata,∗12,∗2 Y. Shimizu,∗2 Y. Shindo,∗15,∗2 L. Stuhl,∗2 T. Sumikama,∗8,∗2 M. Tabata,∗15,∗2
Y. Togano,∗12,∗2 J. Tsubota,∗12,∗2 T. Uesaka,∗2 Z. H. Yang,∗2 J. Yasuda,∗15,∗2 K. Yoneda,∗2 J. Zenihiro,∗2
J. Casal,∗17 M. Gómez-Ramos,∗18 and A. M. Moro∗18
Several experiments have attempted to study thespectroscopy of the unbound isotope 13 Be via both themissing-mass and invariant-mass technique using charge
exchange, fragmentation, proton removal from 14 B, andneutron removal from 14 Be. Even when considering only
the results obtained with the last method,1–4) interpretation of the excitation spectrum is sparse.
We performed a new measurement of neutron removalfrom 14 Be at the RIBF facility using the SAMURAI
spectrometer5) and its standard detectors, in addition
to the MINOS target-tracker system6) surrounded by
gamma detectors from the DALI2 array. For the interpretation of the invariant mass spectrum of 13 Be, we
adopted a novel method, proposed in Ref. 7), whichuses consistent three- and two-body models for 14 Be
and 13 Be, respectively, and can provide predictions forthe absolute cross sections, including the positions andweights of the structures of the spectrum, thus reducing
ambiguities in the analysis. A part of the complexityof the 13 Be continuum spectrum stems from the admixtures of single-particle structures with core-excited components. In this experiment, we were able to measurewith high statistics the possible 12 Be(2+ , 1− ) core excited component that decays via gamma rays.
The relative energy spectrum of 13 Be is shown in
Fig. 1. The absolute cross section is determined taking into account the eﬃciency for invariant-mass measurement and fragment transmission. The spectrum∗1

CEA, Université Paris-Saclay
RIKEN Nishina Center∗3 Center for Nuclear Study, University of Tokyo∗4 Department of Physics, Technische Universität Darmstadt∗5 Department of Physics, Peking University∗6 IPN Orsay∗7 LPC Caen
∗8 Department of Physics, Tohoku University∗9 Department of Applied Physics, University of Miyazaki∗10 Department of Physics, Ehwa Womans University∗11 Department of Physics, University of Tokyo∗12 Department of Physics, Tokyo Institute of Technology∗14 Department of Physics, Kyoto University∗15 Department of Physics, Kyushu University∗16 Department of Physics, Technische Universität München∗17 Dipartimento di Fisica e Astronomia, Universitá di Padova
and INFN∗18 Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla∗2- 39 -

Fig. 1. Left: relative energy spectrum of 13 Be and contributions from core excited components. Right: gamma
spectrum of 12 Be. The two transitions are reproduced by
the sum of an exponential background and the response
functions (dashed curves) of the DALI2 detector obtained
via a GEANT4 simulation.

is characterized by a prominent peak with a maximum at ∼0.48 MeV and a broader structure, peakedat ∼2.3 MeV, extending from ∼1 MeV to ∼5 MeV. The
contribution corresponding to 12 Be(2+ ) and 12 Be(1− )core excited states has been ﬁxed via coincidences with
2.1 and 2.7 MeV gamma transitions, respectively, andis shown for comparison after correcting for gammadetection eﬃciency.
The interpretation of the relative energy and transverse momentum spectrum, described more thoroughly
in Ref. 8), permitted to pin down the dominant ℓ = 1
contribution of the resonant peak observed in the lowlying spectrum, in agreement with2) and at variancewith the conclusions of Refs. 3–4), which assigned a dominant ℓ = 0 content to this peak.
References

1) H. Simon et al., Nucl. Phys. A 791, 267 (2007).
2) Y. Kondo et al., Phys. Lett. B 690, 245 (2010).
3) Y. Aksyutina et al., Phys. Lett. B 718, 1309 (2013).
4) Y. Aksyutina et al., Phys. Rev. C 87, 064316 (2013).
5) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
6) A. Obertelli et al., Eur. Phys. J. A 50, 8 (2014).
7) M. Gómez-Ramos et al., Phys. Lett. B 772, 115, (2017).
8) A. Corsi et al., Phys. Lett. B 797, 134843 (2019).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Overview of the experimental setup of SAMURAI11 to measure the48
Cr(p, n) and 64 Ge(p, n) reactions in inverse kinematics
M. Sasano,∗1 J. Gao,∗1,∗3 L. Stuhl,∗2 Y. Hirai,∗4 T. Wakasa,∗4 D. S. Ahn,∗1 J. K. Ahn,∗13 H. Baba,∗1 K. Chae,∗20
A. Chilug,∗5,∗1 K. Cook,∗15 Y. Fujino,∗7 N. Fukuda,∗1 B. Gao,∗19 S. Goto,∗4 I. S. Hahn,∗8 Y. Hamano,∗4
Z. Halász,∗9 T. Harada,∗10 S. Hong,∗20 S. Huang,∗1,∗3 N. Inabe,∗1 D. Inomoto,∗4 T. Isobe,∗1 H. Kasahara,∗4
D. Kim,∗8 T. Kobayashi,∗14 Y. Kondo,∗15 Z. Korkulu,∗1 A. Krasznahorkai,∗9 H. Miki,∗15 K. Miki,∗14
S. Mitsumoto,∗4 M. Miwa,∗18 T. Motobayashi,∗1 T. Nakamura,∗15 M. Nishimura,∗1 H. Oshiro,∗4 H. Otsu,∗1
V. Panin,∗1 S. Sakaguchi,∗4 D. Sakai,∗14 H. Sakai,∗1 S. Sakaki,∗4 H. Sato,∗1 T. Shimada,∗15 Y. Shimizu,∗1
B. Sun,∗21 X. Sun,∗1,∗3 H. Suzuki,∗1 J. Tanaka,∗1 Y. Togano,∗7 T. Tomai,∗15,∗1 T. Uesaka,∗1 Y. Utsuki,∗14
H. Wang,∗15 X. Xu,∗19 K. Yako,∗2 A. Yasuda,∗15 K. Yoneda,∗1 K. Yoshida,∗1 Y. Yoshitome,∗15 and J. Zenihiro∗1
In this report, we provide an overview of the setup
used in the SAMURAI11 experiment performed at the
RI Beam Factory (RIBF) of RIKEN Nishina Center inthe spring of 2019.
The experiment was performed to measure the (p, n)reaction on 48 Cr and 64 Ge. For each of 48 Cr and 64 Ge,
a secondary cocktail beam was produced via the fragmentation reaction of a 345 MeV/nucleon 78 Kr primarybeam on a 3 mm-thick 9 Be target installed at the F0 focal plane of the BigRIPS separator. The purity of 48 Cr(64 Ge) was 75.9% (58.3%) for a total beam intensity of
1.5 × 105 (1.4 × 105 ) particle/s.
The SAMURAI spectrometer1) was used as the key
device to tag the (p, n) reaction channel through theparticle idenﬁcation of residual beam nuclei. The large
acceptance of the SAMURAI spectrometer was crucial
to detect a wide range of residual nuclei with diﬀerent
masses and proton numbers in the same setup.
Figure 1 shows a schematic view of the experimental setup around the SAMURAI spectrometer. Two
thin plastic scintillators (SBT1,2) were installed downstream of STQ25 for the detection of beam particles.
Two multi-wire drift chambers were installed (BDC1,2)
to tune the beam focus. The secondary beam was transported onto a liquid hydrogen (Liq. H) target with athickness and diameter of 10 and 60 mm, respectively,
at the secondary target position of SAMURAI (F13).
∗1

RIKEN Nishina Center, Japan
Center for Nuclear Study, University of Tokyo, Japan∗3 School of Physics, Peking University, China∗4 Department of Physics, Kyushu University, Japan∗5 Horia Hulubei Nat. Inst. of Phys. and Nucl. Eng., Romania∗7 Department of Physics, Rikkyo University, Japan∗8 Department of Physics, Ewha Womans University, Korea∗9 ATOMKI, Institute for Nuclear Research, HAS, Hungary∗10 Department of Physics, Toho University, Japan∗11 KVI - CART, University of Groningen, The Netherlands∗12 GSI Helmholtzzentrum für Schwerionenforschung, Germany∗13 Department of Physics, Korea University, Korea∗14 Department of Physics, Tohoku University, Japan∗15 Dept. of Physics, Tokyo Institute of Technology, Japan∗16 Department of Physics, University of Tokyo, Japan∗18 Dept. of Physics, Saitama University, Saitama, Japan∗19 Institute of Modern Physics, Chinese Acad. of Sci., China∗20 Department of Physics, Sungkyunkwan University, Korea∗21 School of Physics and Nuclear Engineering, Beihang University, China∗2- 40 -

Fig. 1. Schematic view of the experimental setup aroundthe SAMURAI spectrometer.

The PANDORA neutron detector setup consisted of
37 plastic scintillators and was placed on the left andright sides of the Liq. H target. The neutron-gamma
pulse-shape discrimination (PSD) capability of PANDORA in combination with a new DAQ system basedon digitizers enables the reduction of the gamma-ray
background originating from the enviroment as well asfrom the beam.2) PANDORA was optimized to detect
neutrons with a kinetic energy of 0.1–5 MeV. The reaction residues entered SAMURAI after passing throughthe forward drift chambers, FDC0 and FDC1. The
magnetic ﬁeld of the spectrometer was set to 1.45
(1.36) T for the 48 Cr (64 Ge) beam. At the focal planeof SAMURAI, the beam residue particles were tracked
by FDC2K/3K drift chambers, followed by plastic scintillator walls HODS. In this experiment, a high rate ofaccepted triggers of approximately 5 kHz was achievedby employing a new method.3)
We are grateful to the RIKEN accelerator staﬀ and
CNS, University of Tokyo, for their continuous eﬀorts
to accomplish this stable beam accelration.
References

1) T. Kobayashi, et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
2) L. Stuhl, et al., Nucl. Instrum. Methods Phys. Res. A
866, 164–172 (2017).
3) J. Gao et al., in this report.

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Role of 66 Se in the rp-process nucleosynthesis in type I X-ray bursts
V. Panin,∗1 A. Chilug,∗2 A. Saastamoinen,∗3 Z. Halasz,∗4 D. S. Ahn,∗1 A. Al-Adili,∗5 H. Baba,∗1 K. Cook,∗6
C. Dósa,∗4 Z. Elekes,∗4 N. Fukuda,∗1 J. Gao,∗1 J. Gibelin,∗7 K. Hahn,∗8 G. Hegyesi,∗4 T. Isobe,∗1 D. Kim,∗8
T. Kobayashi,∗1 Y. Kondo,∗6 A. Kurihara,∗6 I. Kuti,∗4 H. Miki,∗6 K. Miki,∗9 T. Motobayashi,∗1 H. Otsu,∗1
M. Sasano,∗1 H. Sato,∗1 T. Shimada,∗6 Y. Shimizu,∗1 L. Sobotka,∗10 I. Stefanescu,∗2 L. Stuhl,∗1 H. Suzuki,∗1
H. Takeda,∗1 Y. Togano,∗11 T. Tomai,∗6 L. Trache,∗2 D. Tudor,∗2 T. Uesaka,∗1 Y. Utsuki,∗9 H. Wang,∗6
A. Yasuda,∗6 K. Yoneda,∗1 and Y. Yoshitome∗6
The important role of 66 Se in the dynamics of therp-process occuring in type I X-ray bursts was pointed
out by several theoretical studies.1,2) The resonant proton capture reaction 65 As(p, γ)66 Se can provide a potential breakout path from the waiting-point nucleus 64 Ge.
Theoretical variations of the rate of this reaction predicta dramatic eﬀect on the resulting chemical abundancesand light curves of the X-ray bursts, while the experimental constrains have not yet been well established.
The experiment NP1406-SAMURAI24 was conductedin March 2019 to measure the time-reversal process,namely one- and two-proton emission from the unboundstates of 66 Se populated by neutron removal from a 67 Se
projectile at 250 MeV/nucleon in a carbon target. A
secondary beam of 67 Se was obtained by the fragmentation of the primary 78 Kr beam at 345 MeV/nucleon
from SRC in a 2 mm Be target. The secondary 67 Se
beam intensity at the end of BigRIPS was on the orderof 103 pps with a purity of approximately 10%.
A schematic of the experimental setup at SAMURAIis shown in Fig. 1. Two carbon targets with thicknesses

CATANA
FDC0
FDC1

SQT25

BDCs

SBT

SAMURAI

B=1.75T
SSDs

FDC2k
FDC3k

Carbon target(0.425 mm and 2 mm)

PDCs
HODP

protons

HODS

67Se
66Se
65As
64Ge

Fig. 1. The experimental setup in NP1406-SAMURAI24.

Fig. 2. Charge identification of outgoing fragments in thefirst SSD and in HODS.

of 0.425 mm and 2 mm were used inside the CATANA
gamma detector3) followed by an array of GLAST-type4)
silicons-strip detectors (SSDs) for coincident measurements of the forward-focused protons and heavy fragments. The SSDs are equipped with dedicated dualgain ASIC preampliﬁers.5,6) In addition, two drift chambers (FDC0 and FDC1) are placed behind the SSDs for
tracking the fragments. The SAMURAI spectrometer isused to separate the reaction products and direct theminto corresponding tracking systems. Protons are measured by two drift chambers (PDCs) and a hodoscope(HODP), and heavy fragments are measured by twoother drift chambers (FDC2k and FDC3k) and a hodoscope (HODS).
Figure 2 shows an example of coincident charge identiﬁcation of the heavy fragments in the ﬁrst SSD behind
the target and in one scintillating bar of HODS witha cut on the 67 Se projectile. Secondary fragmentation
occurring in the beamline materials downstream of thetarget can be clearly identiﬁed. The events on the diagonal line indicate the reactions that occur in the target.
The right panel of Fig. 2 shows the overlap of the same
correlation plot with an additional condition on the coincident proton signal in HODP (black dots). Further
analysis of the experimental data is ongoing.
References∗1

RIKEN Nishina Center
IFIN-HH, Bucharest-Magurele∗3 Texas A&M University∗4 MTA Atomki, Debrecen∗5 Uppsala University∗6 Department of Physics, Tokyo Institute of Technology∗7 LPC Caen
∗8 Ewha Woman’s University, Seoul∗9 Department of Physics, Tohoku University∗10 Washington University in St. Louis∗11 Department of Physics, Rikkyo University

1) A. Parikh et al., Prog. Part. Nucl. Phys. 69, 225 (2013).
2) Y. H. Lam et al., arXiv:1505.02275v1 (2015).
3) Y. Togano et al., Nucl. Instrum. Methods Phys. Res. B,
463, 195 (2020).
4) C. Sgrò et al., Nucl. Instrum. Methods Phys. Res. A, 583,
9 (2007).
5) V. Panin et al., RIKEN Accel. Prog. Rep. 49, 164 (2016).
6) V. Panin et al., RIKEN Accel. Prog. Rep. 51, 148 (2018).

∗2- 41 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Particle identification of light charged particle by SπRIT-TPC in
Sn-Sn isotopic reactions II
M. Kaneko,∗1,∗2 J. Barney,∗2,∗3 G. Cerizza,∗2,∗3 J. Estee,∗2,∗3 W. G. Lynch,∗3 T. Isobe,∗2 G. Jhang,∗2,∗3
M. Kurata-Nishimura,∗2 P. Lasko,∗5,∗2 J. Łukasik,∗5 T. Murakami,∗1,∗2 P. Pawłowski,∗5,∗2 C. Santamaria,∗2,∗7
M. B. Tsang,∗3 J. W. Lee,∗4,∗2 and Y. Zhang∗6,∗2 for the SπRIT collaboration

1.2 Preliminary
min
ina
nary
ry

0.6
0.4
0.2
0
−1.5 −1 −0.5 0 0.5 1 1.5

y(0) = y/ yc.o.m-1

∗2
∗3
∗4
∗5
∗6
∗7

y(0) = y/ yc.o.m-1

Fig. 2. Transverse momentum and normalized rapidity
spectra of protons and deuterons in central 132 Sn+124 Sn
reactions without eﬃciency corrections.

Figure 2 presents preliminary spectra of the transverse momentum pT vs normalized rapidity y (0) without detection-eﬃciency corrections for protons anddeuterons in 132 Sn+124 Sn reactions. The rapidity was
normalized by the center-of-mass rapidity of the reaction system (y c.o.m ) and shifted by −1. A higher track
multipliticy cut, MTPC ≥ 55, was applied for selecting
central collisions. Protons and deuterons were identiﬁed using the angle-dependent mass described above.
The value y (0) = −1 corresponds to the perpendicular emissions, and it is close to the acceptance limitof the TPC. At y (0) ≥ −0.5, approximately symmetric distributions centered at the mid-rapidity, y (0) = 0,
were obtained, which is reasonable as the kinematics
of heavy-ion reactions. To extract physics informationand to compare with model predictions, eﬃciency correction is necessary, which is currently being evaluatedby Monte Carlo simulations.
This work is supported by the Japanese MEXT
KAKENHI Grant No. 24105004; the U.S. DOE underGrant Nos. DE-SC0004835, DE-SC0014530, and DENA0002923; the U.S. NSF Grant No. PHY-1565546;
and the Polish NSC Grant Nos. UMO-2013/09/B/
ST2/04064 and UMO-2013/10/M/ST2/00624. The
computing resources were provided by the HOKUSAI
system at RIKEN.

Fig. 1. Particle identiﬁcation spectra for diﬀerent emission
angles. Overdrawn markers and dotted lines are theGaussian-ﬁtted mean dE/dx values in each 50 MeV/crigidity bin and the results of a simultaneous ﬁt, respectively.
∗1

1

0.8

1.6 Deuteron in 132Sn+124Sn
1.4 Prelim
miin
mi
nary
na
ry
1.2
1
0.8
0.6
0.4
0.2
0
−1.5 −1 −0.5 0 0.5 1 1.5

p T (GeV/c)

1.4 Proton in 132Sn+124Sn

p T (GeV/c)

The main focus of the SπRIT-TPC1) project is toconstrain the high-density nuclear equation of state byusing heavy-ion reactions. SπRIT-TPC is designed tomeasure charged pions as well as light charged particles
from central collisions, which have been predicted to
be sensitive probes of dense nuclear matter.2,3) This
report describes particle identiﬁcation (PID) in TPC
based on the last report5) and the preliminary spectraof protons and deuterons in 132 Sn+124 Sn reactions.
The PID in TPC relies on two measured observables,
namely, the magnetic rigidity and energy deposit perunit length (dE/dx). The truncated-mean method wasapplied for the dE/dx measurement, which was foundto depend on the emission angles. To calibrate theangle dependence of dE/dx, tracks were classiﬁed bytheir pitch (ΘP itch ) and yaw (ΘY aw ) angles, and their
origins are set to the beam-axis direction. Figure 1
shows dE/dx vs magnetic rigidity plots in two diﬀerent angular regions of pitch and yaw angles. The lociof protons, deuterons, and tritons were simultaneously
ﬁtted by the simpliﬁed Bethe-Bloch formula4) for eachregion. As explained in Ref. 5), the mass was calculated from given dE/dx and rigidity values with ﬁtting
parameters. Then, the angle-calibrated observable isobtained.

References

1) R. Shane et al., Nucl. Instrum. Methods Phys. Res. A
784, 513 (2015).
2) M. B. Tsang et al., Phys. Rev. C 95, 044614 (2017).
3) N. Ikeno et al., Phys. Rev. C 97, 069902 (2018).
4) A. A. Mudrokh, A. I. Zinchenko, J. Phys. Conf. Ser.
798, 012071 (2017).
5) M. Kaneko et al., RIKEN Accel. Prog. Rep. 52, 36 (2019).

Department of Physics, Kyoto University
RIKEN Nishina Center
NSCL and Dept. of Phys. & Ast., Michigan State University
Department of Physics, Korea University
Institute of Nuclear Physics, PAN, Kraków, Poland
Department of Physics, Tsinghua University
Lawrence Berkeley National Laboratory, UC Berkeley- 42 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Monte carlo simulation of collective flow analysis for SπRIT-TPC

The SAMURAI Pion-Reconstruction and IonTracker-Time-Projection Chamber (SπRIT-TPC)1)
project aims to constrain the nuclear equation of state(EoS) at supra-saturation density using heavy ion collisions.
In heavy ion collision, the corrective ﬂow, which isone of sensitive probes to the nuclear EoS, characterized by asymmetric azimuthal emission amplitude, v1
and v2 with respect to a reaction plane orientation, Ψ ,v2

M. Kurata-Nishimura,∗1 J. Barney,∗2,∗1 G. Cerizza,∗2,∗1 J. Estee,∗2,∗1 B. Hong,∗3 T. Isobe,∗1 G. Jhang,∗2,∗1
M. Kaneko,∗4,∗1 H. S. Lee,∗7 J. W. Lee,∗3,∗1 J. Łukasik,∗5 W. G. Lynch,∗2 A. B. McIntosh,∗8
T. Murakami,∗4,∗1 P. Pawłowski,∗5,∗1 H. Sakurai,∗1 C. Santamaria,∗2,∗1 R. Shane,∗2
D. Suzuki,∗1 M. B. Tsang,∗2 and S. J. Yennello∗8 for SπRIT Collaboration0

initial

−0.03
−0.04
−0.05
−0.06
−0.07
−0.08

The Ψ is determined from an azimuthal angle distribution of charged particles event by event. In SπRITTPC experiment, the Ψ is calculated summing up unit
vectors of transverse momentum for Z = 1 and 2 particles.2) The detector bias on the Ψ caused by its rectangular shape and a limited acceptance was corrected using shifting and ﬂattening methods.3) The coeﬃcients,
v1 and v2, were obtained after correcting with a reaction plane resolution4) which depends on the laboratory azimuthal angle.
A Monte Carlo simulation was performed to validate
our analysis method. Conﬁgurations of the generated
events were chosen to reproduce distributions of real
data as listed in Table 1. Two acceptance setting for
the SπRIT-TPC and 4π (full) coverage were compared−1

References

∗4
∗5
∗6
∗7
∗8

0

0.5

1
ynrm

by analyzing through the same code developed for realdata.
In Fig. 1, v2 as a function of the center of mass
rapidity were shown for (A)SπRIT-TPC and (B)full
acceptance.The rapidity was normalized by the beam
rapidity, ynrm (≡ ycm /ybeam ). As a result, both ofthem almost reproduce the initial function (green line).
It indicates that the correction for the detector bias
was done properly. However, the absolute v2 are ∼6%smaller at ynrm = 0, whereas v1 reproduces the initialvalue. This discrepancy should be taken into accountas a systematic error.
This work is supported by the U.S. Departmentof Energy under Grant Nos. DE-SC0004835, DESC0014530, DE-NA0002923, US National Science
Foundation Grant No. PHY-1565546, the Japanese
MEXT KAKENHI (Grant-in-Aid for Scientiﬁc Research on Innovative Areas) grant No. 24105004, and
the Polish National Science Center (NCN), under contract Nos. UMO- 2013/09/B/ST2/04064 and UMO2013/10/M/ST2/00624.

Particle
protonMultiplicity 40
dN/dynrm exp(−0.5 ∗ (ynrm /0.78)2 )dN/dutexp(−0.1ut )
3v1
0.52ynrm − 0.18ynrm, const. in ut
2
4
v2−0.08 + 0.1ynrm − 0.02ynrm, const. in ut
Acceptance (A) SπRIT-TPC/(B) Full

∗3

−0.5

Fig. 1. The v2 simulated with (A) SπRIT-TPC and (B)Full acceptance. A green line shows the initial function.

Table 1. Configurations in the Mote Carlo simulation.
The center of mass rapidity normalized with the beam
rapidity was defined as ynrm ≡ ycm /ybeam . The transverse momentum ut (= βt γt ) was utilized.

∗2(B)Full

−0.02

2π dN
= 1+2v1 cos(ϕ−Ψ )+2v2 cos(2(ϕ−Ψ )). (1)N d(ϕ−Ψ )∗1(A)TPC−0.01

1) R. Shane et al., Nucl. Instrum. Methods Phys. Res. A
784, 513 (2015).
2) M. Kurata-Nishimura et al., RIKEN Accel. Prog. Rep.
62, 37 (2019).
3) J. Barrette et al., Phys. Rev. C 56, 3254 (1997).
4) A. M. Poskanzer, S. A. Voloshin, Phys. Rev. C 58, 1671
(1998).

RIKEN Nishina Center
NSCL and Dept. of Phys. & Ast., Michigan State University
Department of Physics, Korea University
Department of Physics, Kyoto University
IFJ PAN, Kraków
Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Kraków
Rare Isotope Science Project, Institute for Basic Science
Cyclotron Institute, Texas A&M University- 43 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Measurement of the proton elastic scatteringfrom 132 Sn at 300 MeV/nucleon
J. Zenihiro,∗1 T. Harada,∗2,∗3 N. Aoi,∗4 H. Baba,∗2 M. Dozono,∗5 F. Endo,∗5 S. Enyo,∗1 Y. Fujikawa,∗1
S. Hanai,∗5 Y. Hijikata,∗1 J. Hwang,∗5 N. Imai,∗5 K. Inaba,∗1 S. Ishida,∗6 T. Isobe,∗2 T. Kawabata,∗7
S. Kiyotake,∗8 A. Kohda,∗4 R. Kojima,∗5 R. Maeda,∗6 Y. Maeda,∗8 Y. Matsuda,∗6 S. Matsumoto,∗1
R. Matsumura,∗2,∗3 B. Mauss,∗2 S. Michimasa,∗5 D. Nishimura,∗9 T. Nishimura,∗8 K. Nosaka,∗6 S. Ota,∗5
H. Sakaguchi,∗4 K. Sakanashi,∗7 H. Shimizu,∗5 D. Suzuki,∗2 J. Tanaka,∗2 S. Terashima,∗10 R. Tsunoda,∗5 andT. Uesaka∗2
The “neutron skin” structure is an important phenomenon in ﬁnite nuclei and is known to be strongly related with the properties of nuclear matter. In neutronrich nuclei, excess neutrons are pushed out to thesurface region, evolving the “neutron skin” structure.
Many mean-ﬁeld predictions indicate that the thicknessof the neutorn skin (∆rnp ), which is deﬁned as the difference in root-mean-square radii between the protonand neutron, is strongly correlated with the equation ofstate (EOS) of the neutron matter. Neutron-rich doubly magic 208 Pb is a benchmarking nucleus for EOS
studies. Thus far, many theoretical and experimental
studies on the ∆rnp of 208 Pb have been conducted.
Proton elastic scattering is a powerful tool to extract
density information and ∆rnp . In the case of stable nuclei, we have established the method to determine neutron density distributions from proton elastic scattering
at 300 MeV.1) It is natural to expand this study to theunstable region, where large ∆rnp values are expected
because of the large isospin asymmetry. To apply our
method to unstable nuclei, we started a new project
to measure the elastic scattering of protons with RI
beams (ESPRI) based on missing mass spectroscopy
in inverse kinematics. We developed a new device, recoil particle spectrometer (RPS), which consists of a
1-mm-thick solid hydrogen target (SHT),2) two multiwire drift chambers (MWDCs), two plastic scintillators,
and fourteen NaI(Tl) calorimeter rods. RPS covers awide range of momentum transfers (0.5–2.5 fm−1 ) corresponding to 10◦ –35◦ in the c.m. scattering angles. We
successfully performed ESPRI measurements with RPS
for several light unstable nuclei.3) We also developed a
new method to determine the proton and neutron density distributions from two-energy proton elastic scattering data at 200 and 300 MeV/nucleon. Usually, theproton density distributions can be derived from the nuclear charge distributions determined by electron elastic
scattering,4) but at present, little information is avail∗1

Department of Physics, Kyoto University
RIKEN Nishina Center∗3 Department of Physics, Toho University∗4 RCNP, Osaka University∗5 CNS, University of Tokyo∗6 CYRIC, Tohoku University∗7 Department of Physics, Osaka University∗8 Department of Applied Physics, Miyzaki University∗9 Department of Natural Sciences, Tokyo City University∗10 School of Physics, Beihang University∗2- 44 -

able on the charge distributions of unstable nuclei. Thismethod is based on the diﬀerent energy dependences between pp and pn interactions, which was demonstrated
by the proton elastic scattering data of Zr isotopes at
200 and 300 MeV/nucleon.1)
132
Sn is another benchmarking nucleus, which has
a larger isospin asymmetry than that of 208 Pb. In
November 2019, we successfully completed the ESPRI
experiment for 132 Sn at 300 MeV/nucleon (NP1512RIBF79R1). The ﬁrst part of this experiment at
200 MeV/nucleon was already completed in 2016.5) A
secondary beam around 132 Sn at 300 MeV/nucleon was
produced by ﬁssion fragmentation with a 238 U beamat 345 MeV/nucleon. In this experiment, the purity of132
Sn was ∼20%, and the total intensity of the cocktail
beam was ∼700 kcps. Since high-intensity and heavy RI
beams cause critical radiation damage to and/or low efﬁciencies of detectors such as plastic scintillators, delayline parallel-plate avalanche counters (DL-PPACs), andion chambers, in place of the standard ones at BigRIPS,
we have used new detectors with good radiation hardnesses and fast timing responses, namely, diamond detectors, MWDCs, strip-readout PPACS (SR-PPACs),and Xe gas scintillators.6) The secondary beam particles were transported to F8 and ﬁnally to the SHT at
F12, where RPS was installed. At F8, a CNS active
target (CAT) was also installed for measurement at a
forward scattering angle around 7◦ –10◦ in the c.m. angles. A new high-speed DAQ system, MOCO with parallelized VME (MPV),7) was introduced for the ﬁrst
time, and it worked with a good live-time ratio under ahigh-data-rate condition. During the measurement, weclearly identiﬁed elastic events from the correlation ofrecoil proton energies and angles.
References
1) H. Sakaguchi et al., Prog. Part. Nucl. Phys. 97, 1 (2017).
2) Y. Matsuda et al., Nucl. Instrum. Methods. Phys. Res.
A 643, 6 (2011).
3) Y. Matsuda et al., Phys. Rev. C 87, 034614 (2013).
4) H. De Vries et al., At. Data Nucl. Data Tables 36, 495(1987).
5) J. Zenihiro et al., RIKEN Accel. Prog. Rep. 50, 54(2017).
6) J. Zenihiro et al., RIKEN Accel. Prog. Rep. 51, 156(2018).
7) H. Baba et al., in this report.

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

TDPAD measurement for the 10− isomer of 98 Y
J. M. Daugas,∗1,∗2,∗3 F. Boulay,∗1,∗2,∗4 Y. Ichikawa,∗2 A. Takamine,∗2 D. S. Ahn,∗2 K. Asahi,∗2,∗5 H. Baba,∗2
D. L. Balabanski,∗2,∗6 T. Egami,∗2,∗7 T. Fujita,∗2,∗8 N. Fukuda,∗2 C. Funayama,∗2,∗5 T. Furukawa,∗2,∗9
G. Georgiev,∗10 A. Gladkov,∗2,∗11 M. Hass,∗12 K. Imamura,∗2,∗13 N. Inabe,∗2 Y. Ishibashi,∗2,∗14 T. Kawaguchi,∗2,∗7
T. Kawamura,∗8 W. Kim,∗11 Y. Kobayashi,∗15 S. Kojima,∗2,∗5 A. Kusoglu,∗10,∗16 R. Lozeva,∗10 S. Momiyama,∗17
I. Mukul,∗12 M. Niikura,∗17 H. Nishibata,∗2,∗8 T. Nishizaka,∗2,∗7 A. Odahara,∗8 Y. Ohtomo,∗2,∗5 D. Ralet,∗10
T. Sato,∗2,∗5 G. S. Simpson,∗18 Y. Shimizu,∗2 T. Sumikama,∗2 H. Suzuki,∗2 H. Takeda,∗2 L. C. Tao,2,19
Y. Togano,∗5 D. Tominaga,∗2,∗7 H. Ueno,∗2 H. Yamazaki,∗2 and X. F. Yang∗20
0.20

340

3

300

R(t)

0.10
0.05
0
-0.05
-0.10
-0.15

0.08

(b) A=7.5(21)%

R(t)

0.04
0
-0.04
-0.08
0.15

(c)

0.10

2 1

0.05
0
-0.05

260

Yield (pps/mm)(a) A=17(4)%

0.15

R(t)

A time-diﬀerential perturbed angular distribution(TDPAD) measurement was performed for the 10− isomer 98m Y. The ﬁrst aim of this experiment was to investigate the single-particle structure and on the wave
functions of 98m Y, which is located in a region with arapid change of the ground-state nuclear shape, throughthe magnetic moment. The second aim was to measure
the amount of spin alignment of the isomeric states produced by the abrasion-ﬁssion reaction.
Neutron-rich N = 59 isotones were produced by theabrasion-ﬁssion reaction of a primary 238 U beam at
345 MeV/nucleon incident on a 100-µm-thick 9 Be target. A thin target was used to avoid the mixing of different momentum distributions if the reaction occurredat the entrance or exit of the target. Figure 1 shows thethree selections in the momentum distribution of 98 Y

-0.10
200

220

400

600

800

1000

1200

1400

Time (ns)180

Fig. 2. (a), (b), and (c) represent the R(t) ratio of 98m Y forselections 1, 2, and 3, respectively. See Refs. 1–2) for thedefinition of R(t).

140
100
60
20
-300

-260

-220

-180

-140

-100

-60

-20

20

60

100

X (mm)

Fig. 1. Selections in the momentum distribution of
distribution shape was estimated by LISE++.

98

Y. The∗1

CEA, DAM, DIF
RIKEN Nishina Center∗3 LCM, LNE-CNAM∗4 GANIL, CEA/DSM-CNRS/IN2P3∗5 Department of Physics, Tokyo Institute of Technology∗6 ELI-NP, IFIN-HH∗7 Department of Advanced Sciences, Hosei University∗8 Department of Physics, Osaka University∗9 Department of Physics, Tokyo Metropolitan University∗10 IJCLab, CNRS/IN2P3, Université Paris-Saclay∗11 Department of Physics, Kyungpook National University∗12 Department of Particle Physics, Weizmann Institute of Science∗13 Department of Physics, Meiji University∗14 Department of Physics, University of Tsukuba∗15 Department of Informatics and Engineering, University ofElectro-Communication∗16 Department of Physics, Istanbul University∗17 Department of Physics, University of Tokyo∗18 LPSC, CNRS/IN2P3, Université Grenoble Alpes∗19 School of Physics, Peking University∗20 Instituut voor Kern- en Stralingsfysica, K. U. Leuven∗2- 45 -

at F1. The selected isotones were implanted in a nonperturbating copper host at F8. The TDPAD apparatus
located at F8 was same as in Refs. 1–2), and an external
magnetic ﬁeld of 0.250 T was applied.
Figures 2 (a), (b), and (c) show the TDPAD spectrawith respect to the momentum distribution, where thehighest spin alignment of 17(4)% is located in its outerwing and no spin alignment exists at the center. The
g-factor of 98m Y was deduced to be |g| = 0.36(2). Thisvalue is far from the one expected under the assumptionof a (πg9/2 ⊗ h11/2 )10− conﬁguration, where the additivity rules give g = +0.517 considering the g-factorsof the 9/2+ and the 11/2− isomers of 97 Y and 99 Mo,
respectively.3,4) The interpretation of this result needs
improvement in theoretical calculations for the odd-odd
mass isotopes in this interesting region.
References

1) Y. Ichikawa et al., Nature Phys. 15, 321 (2019).
2) F. Boulay et al., Phys. Rev. Lett. 124, 112501 (2020).
3) B. Cheal et al., Phys. Lett. B 645, 133 (2007).
4) J. M. Daugas, private communication.

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Investigations of magnetic moments andspin alignment in Coulomb fission reaction

As one of the most accurate probes of the nuclear wave-functions, the magnetic moments of excitedstates in nuclei are both important and interesting.
Their measurement has several diﬃculties and particularities. One of the most crucial ones is the spin alignment of the nuclear ensemble which is produced in thereaction populating the nucleus of interest. In such an
experiment we have investigated the Coulomb ﬁssion
reaction, which was not previously studied, aiming toprobe the nuclear alignment trough the measurementof magnetic moments.
Nuclei around 132 Sn form a key region of the nuclear
chart from astrophysics and nuclear structure pointof view. In particular, below 132 Sn, several isomeric
structures emerge as for example in the 124, 125 Ag isotopes, which have interesting behaviour of the three
proton holes below Z = 50 closed-shell coupled to evenor odd amount of neutron holes from predominantly
the last three νh11/2 , d3/2 and s1/2 neutron orbitals
below N = 82.1) Measuring nuclear moments of such
excited isomeric states allows to ﬁnd what type of conﬁgurations are formed in these nuclei, and at the sametime, investigate unknown properties of the ﬁssion reaction mechanism.
The experiment was carried out in December 2019 at
the RIBF using the BigRIPS spectrometer. Primary238
U beam with an energy of 345 MeV/nucleon and an
intensity of the order of 100 pnA was used to induce
Coulomb ﬁssion onto a thin 184 W production target.
This very thin foil of only 0.1 mm was used for the ﬁrst
time in our experiment and performed well at the usedvery high ﬂux. The isotopes of interest produced in
the reaction were separated, transported and identiﬁedusing the standard methods for BigRIPS and using Al
wedges at the F1 and F5 focal planes of 7 mm and
1 mm, respectively. Our detection setup was placedat the F8 focal plane where the beam was stopped ina sandwich of 2 mm thick plastic and 3 mm thick Cu
host.
The momentum distribution for ions produced in theﬁssion reaction is generally wide and it is only partiallyaccepted (e.g. ±3%) by the BigRIPS spectrometer.2)
∗1
∗2
∗3
∗4
∗5
∗6
∗7

Z

R. Lozeva,∗1 G. Häfner,∗1,∗2 M. Si,∗1 Y. Ichikawa,∗3 H. Ueno,∗3 D. S. Ahn,∗3 K. Asahi,∗3 T. Asakawa,∗3,∗4
H. Baba,∗3 A. Esmaylzadeh,∗2 N. Fukuda,∗3 A. Gladkov,∗3 K. Imamura,∗3 N. Inabe,∗3 K. Kawata,∗3,∗5
L. Knaﬂa,∗2 A. Kusoglu,∗6 M. Niikura,∗7 Y. Sasaki,∗3,∗4 H. Sato,∗3 Y. Shimizu,∗3 H. Suzuki,∗3 M. Tajima,∗3
A. Takamine,∗3 H. Takeda,∗3 Y. Takeuchi,∗3,∗4 Y. Yanagisawa,∗3 H. Yamazaki,∗3 and K. Yoshida∗3

49

10

3

48
124

Ag

47

102

125

Ag

46

10

2.6

2.62

2.64

2.66

2.68

A/Q

Fig. 1. Particle-identification for the central setting.

In addition, in order to select certain parts of this momentum we have performed F1 slit cuts by accepting
only the high or only the low part of momentum distribution for the ions of interest.
Typical particle-identiﬁcation spectrum from thisexperiment for the central selection is shown in Fig. 1
for about 10% of the collected data. Similar statistics was obtained also for the wing setting. For themeasurement of the nuclear moments we have employed the well-known TDPAD method, applied successfully at RIBF.3,4) We used four HpGe detectors at
90◦ with respect to each other and two LaBr3 detectorsof 1.5 × 1.5 in. They were all placed in a horizontal
plane, while the magnetic ﬁeld used to induce the precession of the nuclear spins was provided by a compact
electromagnet and applied in a vertical direction.
Data analysis for the oscillation pattern and magnetic moment for the nuclei of interest are currently inprogress.
References

1) S. Lalkovski et al., Phys. Rev. C 87, 034308 (2013).
2) T. Kubo et al., Nucl. Instrum. Methods Phys. Res. B
204, 97 (2003).
3) Y. Ichikawa et al., Nat. Phys. 15, 321 (2019).
4) F. Boulay et al., Phys. Rev. Lett. 124, 112501 (2020).

Université Paris-Saclay, CNRS/IN2P3, IJCLabIKP, University of Cologne
RIKEN Nishina Center
Department of Advanced Sciences, Hosei University
Center for Nuclear Study, University of Tokyo
Department of Physics, Istanbul University
Department of Physics, University of Tokyo- 46 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Magnetic-moment measurement of the isomeric state of 130 Sn in thevicinity of the doubly—magic nucleus 132 Sn
G. Georgiev,∗1,∗2,∗3 Y. Ichikawa,∗1 D. S. Ahn,∗1 T. Asakawa,∗4 K. Asahi,∗1 H. Baba,∗1 K. Doi,∗4 N. Fukuda,∗1
A. Gladkov,∗1,∗5 T. Gray,∗3 G. Häfner,∗2,∗6 K. Kawata,∗1,∗7 W. Kobayashi,∗4 A. Kusoglu,∗8 G. J. Lane,∗1,∗3
R. L. Lozeva,∗2 C. Mihai,∗9 R. Mihai,∗9 Y. Nakamura,∗10 M. Niikura,∗11 H. Nishibata,∗1 A. Odahara,∗12
S. Pascu,∗9 M. Sanjo,∗4 Y. Sasaki,∗4 T. Sato,∗1 Y. Shimizu,∗1 E. Simpson,∗3 C. Sotty,∗9 A. Stuchbery,∗3
T. Sumikama,∗1 H. Suzuki,∗1 M. Tajima,∗1 A. Takamine,∗1 H. Takeda,∗1 Y. Takeuchi,∗4 A. Toda,∗5
A. Turturica,∗9 H. Ueno,∗1 and H. Yamazaki∗1
The region around 132 Sn has attracted much experimental and theoretical interest recently due toits doubly—magic character. A microsecond isomericstate has been observed experimentally in 130 Sn1–3)(t1/2 = 1.6 µs). Its tentative spin-parity assignment of
10+ suggests a neutron h211/2 conﬁguration, which, due
to its high spin, is expected to have a very pure wavefunction conﬁguration. A magnetic moment study on
this isomeric state should be able to shed light on therobustness of the double shell closure (Z = 50 and
N = 82) at 132 Sn.
The NP1712-RIBF143R1 experiment was performedin December 2018 at the BigRIPS separator at RIBF.
A two-step fragmentation scheme4) was employed to
produce a spin-aligned 130 Sn beam. A secondary
beam of 132 Sn was produced following the ﬁssion of
a 345 MeV/nucleon 238 U beam on a 6 mm 9 Be target
at F0. A wedge-shaped aluminium degrader (having amean thickness of 6 mm), positioned at the F1 dispersive focal plane, was used for the secondary-beam puriﬁcation. The momentum acceptance was restricted
to ±1.4% using the F1 momentum slits. A tertiary
beam of 130 Sn was produced with a wedge-shaped(2 mm) aluminium secondary target placed at the F5
momentum-dispersive focal plane. A two-neutron (2n)removal reaction mechanism was used to populate the10+ isomeric state of interest. Special care was taken
to match the momentum dispersion between F5 and F7
to that between F3 and F5. The momentum slits at
F7 were set to ±9 mm, which corresponds to ±0.26%
momentum selection. A beam intensity of 30 pps, witha purity of ∼20%, was obtained for 130 Sn.
The isomeric states of interest were implanted in
a 3 mm Cu host positioned between the poles of anelectro-magnet in the center of the time-diﬀerential
perturbed angular distribution (TDPAD) apparatus at

the F12 focal plane.
Four Ge and two LaBr3 detectors, positioned 7 cm
from the host in a horizontal plane around the magnet, were used to monitor the γ-rays from the decayof the isomeric state. The dipole magnet provided astatic magnetic ﬁeld of B = 0.150 T in the verticaldirection. A 0.1 mm plastic scintillator, placed upstream of the stopper, provided the t = 0 signal forisomeric-decay measurement. The TDPAD techniqueentails observing the modulation of the angular distribution of the isomeric γ-rays due to the rotation of thenuclear spin ensemble in the magnetic ﬁeld with theLarmor frequency ωL = gµN B/h. This is realized byconstructing a ratio function (R(t)), which combines
detectors positioned at 90◦ with respect to each other.
Provided that the magnetic ﬁeld at the nuclear site iswell known, one can readily determine the g factor of
the state of interest from the oscillation pattern in theR(t) function.
Two γ-rays (97 keV and 391 keV) were observed fromthe decay of the isomeric state, as expected from thepreviously known decay scheme. Their lifetimes, determined from the time spectra, were in agreement withthe previously observed lifetime of the isomeric state.
An oscillation pattern with a statistical signiﬁcance of
2.7σ was observed during the analysis of the ratio function. It indicates a gyromagnetic factor very close to
the free-nucleon Schmidt limit, in contrast with theg factors of other h11/2 states in the region, for which
a reduction of about 30% of the free-nucleon g factors(gseﬀ = 0.7 × gsfree ) is observed. This very small reduction of the g factor compared to the Schmidt-limit
indicates a very robust double—shell closure at 132 Sn.
Following this observation, a new proposal has been
submitted to the RIKEN NP PAC in December 2019.
It aims at conﬁrming this very intriguing indication
with a higher statistical signiﬁcance.

∗1

RIKEN Nishina Center
CSNSM, CNRS/IN2P3, Université Paris-Saclay∗3 Department of Physics, Australian National University∗4 Department of Advanced Sciences, Hosei University∗5 Department of Physics, Kyungpook National University∗6 Department of Physics, University of Cologne∗7 Center for Nuclear Study, University of Tokyo∗8 ELI-NP, IFIN-HH∗9 NIPNE, IFIN-HH∗10 Department of Physics, Meiji University∗11 Department of Physics, University of Tokyo∗12 Department of Physics, Osaka University∗2

References

1) R. L. Lozeva et al., Phys. Rev. C 77, 064313 (2008).
2) D. Kameda et al., Phys. Rev. C 86, 054319 (2012).
3) S. Pietri et al., Phys. Rev. C 83, 044328 (2011).
4) Y. Ichikawa et al., Nat. Phys. 8, 918 (2012).

- 47 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Isomeric-to-ground state ratio of 128 Sn measured by Rare RI Ring
H. F. Li,∗1,∗2,∗3 S. Naimi,∗1 D. Nagae,∗1 Y. Abe,∗1 F. Suzaki,∗1 Y. Yamaguchi,∗1 M. Wakasugi,∗1 S. Omika,∗4
K. Inomata,∗4 H. Arakawa,∗4 S. Hosoi,∗4 K. Nishimuro,∗4 Y. Inada,∗4 T. Kobayashi,∗4 D. Kajiki,∗4
D. Hamakawa,∗4 W. B. Dou,∗4 T. Yamaguchi,∗4 M. Mukai,∗5 T. Moriguchi,∗5 R. Kagesawa,∗5 D. Kamioka,∗5
A. Ozawa,∗5 S. Suzuki,∗2 Z. Ge,∗2 C. Y. Fu,∗2 Q. Wang,∗2 M. Wang,∗2 S. Ota,∗6 S. Michimasa,∗6
N. Kitamura,∗6 S. Masuoka,∗6 D. S. Ahn,∗1 H. Suzuki,∗1 N. Fukuda,∗1 H. Takeda,∗1 Y. Shimizu,∗1
Y. A. Litvinov,∗7 G. Lorusso,∗8 and T. Uesaka∗1

wherec T1 and T0 are the time-of-flight (TOF) of the nucleus of interest and reference nucleus, respectively, andBρ1 is the magnet rigidity of the nucleus of interest.1)
The unknown mass m1 is determined relative to the massof the isochronous reference nucleus m0 . Bρ tagging is
performed at the momentum-dispersive focal plane F5 of
BigRIPS by measuring the horizontal position with twoparallel-plate avalanche counters (PPACs). The TOF ofthe nuclei in R3 was measured using the E-MCP detector2) at S0 of SHARAQ and a plastic scintillator placed
69822022

Entries(a)18.66 / 2118698200

Amp 1

17.21  2.55

16

Mean 1693707.81  0.34

14

Sigma12.34  0.30

Amp 2

20.79  2.28

Mean 2693720.06  0.33

Sigma2

3.55  0.30

T1 (ns)2 / ndf

count

69818012693740
10

(ns)

260

260

69821020698190(b)

8693730

Entries

260

693720469371026937000693680 693700
12
106937208693740 693760 693780
6
4
2
0
corr

T1F5x(ns)(mm)

6938002

Fig. 1. (a), (b) Correlations between T1 and Tcorr, respec1
tively, and the F5 position for 128 Sn.
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

20

128

18

m

Sn

16
14
12

128

Sn

10
8
6

Entries260

2 / ndf

18.66 / 21

Amp 1

17.21  2.55

Mean 1693707.81  0.34

Sigma12.34  0.30

Amp 2

20.79  2.27

Mean 2693720.06  0.33

Sigma2

3.55  0.30

42
0693680693700693720693740corr

T1

693780693800Fig. 2. Tcorr
spectrum of 128 Sn; two Gaussian functions were1
used to fit the histogram.

behind R3.
In the autumn of 2018, the first mass measurement
campaign was conducted at R3. To measure the mass of
125
Ag and 124 Pd, 3 neighbor isotones, 126 Cd, 127 In, and128
Sn, were injected in R3 as reference nuclei to determine the mean Bρ value of R3.3) The first isomeric stateof 128 Sn, the excitation energy and half-life of which areabout 2091.5 keV and 6.5 s,5) respectively, was produced
and observed during this experiment. The TOF in R3
for each particle was normalized to the same turn numbers4) to determine T1 . The correlation between the T1of 128 Sn and the F5 position is shown in Fig. 1(a). Af’s dependence
ter event-wise correction with Bρ, Tcorr
1on the F5 position is shown in Fig. 1(b). The isomericstate and ground state of 128 Sn can be well resolved in
the spectrum of Tcorr, as shown in Fig. 2. The left peak1is the ground state of 128 Sn, and the right one is theisomeric state. A function composed of the sum of two
Gaussian functions was used to fit this spectrum.
The mass resolving power of R3 can be given by(2)

which is derived from Eq. (1). The full width at half
maximum of the achieved mass resolving power is about
125,000 from the ground-state peak. The isomeric-toground state ratio for 128 Sn is 1.8(4), which is determined by the integral values’ ratio of the fitting functions.
References

RIKEN Nishina Center
Institute of Modern Physics, Chinese Academy of Sciences
University of Chinese Academy of Sciences
Department of Physics, Saitama University
Institute of Physics, University of Tsukuba
Center for Nuclear Study, University of Tokyo
GSI Helmholtzzentrum für Schwerionenforschung
NPL, University of Surrey

693760(ns)

R = m/∆m = T1corr /∆T1corr ,

6

T1

corr

Entries

22

count

The excitation energy of the isomeric state and theisomeric-to-ground state ratios are very important tounderstand the nuclear structure and reactions. Direct
mass measurement can be used for measuring the excitation energy of the long-lived isomeric state and determining the isomeric-to-ground state ratio simultaneously. Rare RI Ring (R3) is an isochronous mass spectrometer in RIBF. The principle of the mass measurement at R3 is described by the following equation:
�
( )2
�
�
T0
1
−
corr
�
T1
m0 T1
m0 1 �
m1==
T1 � 1 + ()2 , (1)q1
q 0 T0
q0 T0
m0 /q0cBρ11) A. Ozawa et al., Prog. Theor. Exp. Phys. 2012, 03C009(2012).
2) Y. Abe et al., JPS Conf. Proc. 1, 013059 (2014).
3) S. Naimi et al., RIKEN Accel. Prog. Rep. 52, 102 (2019).
4) H. F. Li et al., RIKEN Accel. Prog. Rep. 52, 52 (2019).
5) G. Audi et al., Chin. Phys. C 41, 030001 (2017).
- 48 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Performance study of electron spectrometer for SCRIT experiments

tic
as
El

eV

280

pe
tic
as
ea
k
cp
sti
El
a

9.

270

290

300
310
Pe [MeV/c]

Fig. 1. Reconstructed momentum spectra of scattered electrons for diﬀerent scattering-angle regions.
∗1
∗2
∗3
∗4

4.4 MeV,

9.6 MeV, this work

9.6 MeV,

4)

4)

ary

Ver

2

1

1.1

1.2

1.3

1.4
[fm-1]

eff

neously. In addition, a magnetic-ﬁeld measurement
was performed to study the momentum resolution of
WiSES.
In 2019, we performed a series of electron-scatteringexperiments with carbon targets to evaluate the acceptance and momentum resolution of the spectrometer
after the measurement of the magnetic-ﬁeld distribution of the spectrometer magnet. The status of theﬁeld measurement is reported elsewhere.3)
Figure 1 shows reconstructed momentum spectrafrom the center of targets for an electron beam energyof 300 MeV and three scattering angle regions: 40◦ –45◦ , 45◦ –50◦ , and 50◦ –55◦ . One elastic peak and two
inelastic peaks are clearly observed. Figure 2 shows
yield distributions with varying eﬀective momentum
transfer after acceptance corrections. In the present
analysis, only the radiation tail from the elastic peakis taken into account for counting the yields. Moreover,
the acceptances for the elastic and inelastic events are
assumed to be the same. Although the distributions of
the elastic events are consistent between this work anda previous experiment,4) those of the inelastic eventsshow ﬁnite discrepancies.
Further analysis is ongoing to evaluate the performance of the spectrometer.

ak

0
260

6

40

4.4 MeV, this work

Fig. 2. Yield distributions with varying eﬀective momentum transfer after acceptance corrections. Filled circles
indicate preliminary results from this work. Opened
circles are from Ref. 4).

El

eV
M

 : 50-55 [deg]

eV
4.
4
M

0
80

eV

100

Elastic,q4.
4

 : 45-50 [deg]
4.
4

200

4)

Elastic, this work

in
relim

103

0.9

0

M

counts/(0.25 MeV/c)

400

104

10

pe

Ee : 300 [MeV] : 40-45 [deg]

M

800

105

yp

ak

We constructed the Self-Conﬁning Radioactive Ion
Target (SCRIT) electron scattering facility1) to perform electron scattering experiments for short-lived
unstable nuclei. Such experiments have been long desired but unrealized thus far because of the diﬃculties in preparing a thick target from such short-lived
nuclei. SCRIT is a novel technique to achieve a sufﬁciently high luminosity to perform electron scattering experiments by trapping the target ions along theelectron beam. After successful commissioning experiments with stable targets,2) we started to prepare foran experiment with an unstable nuclear target.
The SCRIT electrode was replaced with a new one
that has a larger cross section and less material aroundthe trapping region, in addition to providing a much
more uniform electric potential. Simultaneously, threeidentical carbon foils with a thickness of 35 µm were
installed as ﬁxed targets at the center and both edgesof the SCRIT electrodes, respectively, to evaluate theperformance of the electron spectrometer, windowframe spectrometer for electron scattering (WiSES).
The carbon targets can be moved out of the electronbeam axis when they are not in use. For WiSES, thedrift chamber in front of the spectrometer magnet was
replaced with a new one with both vertical and horizontal wires to reconstruct the horizontal and verticaltrajectory information of scattered electrons simulta-

Yield (arb. units)

K. Tsukada,∗1,∗2 A. Enokizono,∗2 Y. Honda,∗1,∗2 K. Kurita,∗3 H. Ohnishi,∗2 S. Sato,∗3 T. Suda,∗1,∗2 S. Takagi,∗4
D. Taki,∗1,∗2 T. Tamae,∗1,∗2 M. Watanabe,∗2 M. Wakasugi,∗2,∗4 and H. Wauke∗1,∗2

References

1) M. Wakasugi et al., Phys. Rev. Lett. 100, 164801(2008).
2) K. Tsukada et al., Phys. Rev. Lett. 118, 262501 (2017).
3) H. Wauke et al., in this report.
4) J. H. Fregeau et al., Phys. Rev. 104, 225 (1956).

ELPH, Tohoku University
RIKEN Nishina Center
Department of Physics, Rikkyo University
Institute for Chemical Research, Kyoto University- 49 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Correlated measurement of mass and decay of fusion evaporation
products for 51 V+159 Tb reactions via MRTOF+α-TOF detector

The SHE-Mass-II facility1) is a system with a multireﬂection time-of-ﬂight mass spectrograph (MRTOFMS2) ) coupled with the gas-ﬁlled recoil ion separator
GARIS-II3) in the E6 experimental room for the massmeasurement of fusion evaporation products, such asvery low yield nuclei in the superheavy region.
Recently, we developed and installed a novel detector
named α-TOF4) , which simultaneously records the timeof-ﬂight (TOF) signal and successive α-decay. The αTOF detector has the capability to signiﬁcantly reducethe background level.
The experiment was performed using 51 V+159 Tb
reactions.
A 51 V beam was accelerated up to
6.0 MeV/nucleon by RRC. The beam energy on the target was reduced by an aluminum degrader to approximately 4.8 MeV/nucleon. A 460-µg/cm2 -thick 159 Tb
220

200
180

(a) Singles ToF

207Ra2+

160
140
120
100

207Fr2+

Counts / 3.2 ns

80
60

y
r
a

40
20

2200

200
180

m
i
l
e

160
140
120
100
80
60
40
20
0

in

94.10594.10694.107(b) 207Ra gated ToF

pr94.10894.1096×10207Ra2+

6

94.10594.10694.107

ToF [0.1 ns]

94.10894.109×10

Fig. 1. (a) Singles TOF spectrum. (b) TOF spectrum incoincidence with 207 Ra α-decays obtained using a time
gate of 5s.
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

∗9

Department of Physics, Kyushu University
RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), KEK
Japan Atomic Energy Agency
Graduate School of Science and Engineering, Yamagata University
Department of Chemistry and Biochemistry, New Mexico
State University
Department of Nuclear Physics, The Australian National University
Department of Physics, Osaka University.
Institute for Basic Science

ToF [0.1ns]

T. Niwase,∗1,∗2,∗3 M. Wada,∗3 P. Schury,∗3 Y. Ito,∗4 S. Kimura,∗2 D. Kaji,∗2 M. Rosenbusch,∗2 Y. X. Watanabe,∗3
Y. Hirayama,∗3 H. Miyatake,∗3 J. Y. Moon,∗9 H. Ishiyama,∗2 K. Morimoto,∗2 H. Haba,∗2 T. Tanaka,∗7
S. Ishizawa,∗5,∗2,∗3 P. Brionnet,∗2 S. Iimura,∗8,∗2,∗3 A. Takamine,∗2 K. Morita,∗1,∗2 and H. Wollnik∗6

in

m
i
l
e

pr

y
r
a

Energy [keV]

Fig. 2. Two-dimensional mapping of TOF versus correlated
α-decay energies.

target was prepared by a sputtering method on a 3.0 µm
Ti backing foil.
The fusion evaporation residues (ERs) were separated
from the primary beam and eﬃciently transported using GARIS-II. After decelerating ERs using a Mylar foil,
the ERs were captured in a cryogenic high-purity He gas
catcher, and the thermalized ions were extracted by an
RF-carpet and transported to the MRTOF-MS via multiple RF ion traps. We observed the 206, 207 Fr, 206, 207 Ra
and 204 Rn isotopes extracted as doubly charged ions.
In this measurement, we focused on 206, 207 Ra isotopes
having relatively short half-lives, i.e., T1/2 = 240 ms for206
Ra and T1/2 = 1.38 s for 207 Ra.
Figure 1 shows a part of the TOF spectrum at A =207. When we gated the ToF spectrum by the αray energy of 207 Ra with a coincident time of 5 s (3.5
half-lives), we clearly discriminated the decay-correlated
TOF events (Fig. 1(b)).
Figure 2 shows a part of the two-dimensional spectrum for TOF and the correlated α-decay energies. Fromthe correlation mapping, we obtained the informationof TOF, as well as decay properties such as α-energy
and decay time, atom by atom. Further analysis is inprogress.
References

1) M. Wada et al., RIKEN Accl. Prog. Rep. 52, 136 (2019).
2) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B,
335, 39 (2014).
3) D. Kaji et al., Nucl. Instrum. Methods Phys. Res. B, 317,
311 (2013).
4) T. Niwase et al., Nucl. Instrum. Methods Phys. Res. A,
953, 163198 (2020).

- 50 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Half-life determination of nuclear excited states of 229 Th by thecoincidence measurement between α particles and γ rays from 233 U
Y. Shigekawa,∗1,∗2 A. Yamaguchi,∗3 K. Suzuki,∗4 H. Haba,∗1 T. Hiraki,∗4 H. Kikunaga,∗5 T. Masuda,∗4
S. Nishimura,∗1 N. Sasao,∗4 A. Yoshimi,∗4 and K. Yoshimura∗4
Studying the nuclear structure of 229 Th is importantin that reflection-symmetric and reflection-asymmetricshapes are expected to coexist1) and the first nuclear excited isomeric state of 229 Th (229m Th) has an extremely
low energy of 8.3 eV,2) which would enable the development of nuclear laser spectroscopy and an ultraprecise
nuclear clock. In this study, we measured the half-livesof nuclear excited states of 229 Th, populated through thealpha decay of 233 U, for further understanding of the nuclear properties of 229 Th. This work was also aimed atdetermining the half-life of the 29.2-keV state (Fig. 1).
This half-life was one of the key parameters for exciting 229 Th from the ground state to the 29.2-keV statewith synchrotron radiation to actively produce 229m Th,
which was recently realized by our group.3)
For the half-life determination, we performed a coincidence measurement between α particles and γ rays froma 233 U source prepared by electrodeposition. The 233 U
source was placed inside a vacuum chamber enclosed by
5-cm Pb blocks for background γ-ray reduction. Emitted α particles from the source were measured with apassivated implanted planar silicon detector mounted inside the chamber, and γ rays that were emitted from thesource and passed through a polyimide window out ofthe vacuum were measured with a LaBr3 (Ce) scintillator and photomultiplier. After amplification, α-particle

Fig. 1. Excited states of 229 Th the half-lives of which were
determined, and α and γ transitions used for determining
the half-lives (unit: keV).
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Graduate School of Science, Osaka University
Quantum Metrology Laboratory, RIKEN
Research Institute for Interdisciplinary Science, Okayama University
Research Center for Electron Photon Science, Tohoku University- 51 -

Fig. 2. Time spectrum of γ-ray signals following α-particle
signals for 4783.5-keV α particles and 42.4-keV γ rays
(histogram). A single exponential decay function convoluted with a Gaussian function is fitted to the data
(curve).

and γ-ray signals were recorded with Computer-Aided
Measurement And Control (CAMAC) modules to obtaintime spectra of γ-ray signals following α-particle signals
for each combination of α-particle and γ-ray energies.
Figure 2 shows a time spectrum for 4783.5-keV α particles and 42.4-keV γ rays. The half-life obtained fromthe fitting of a single exponential decay function convoluted with a Gaussian function was almost the sameas the reference value (172(6) ps).4) From a time spectrum for 4783.5-keV α particles and 29.2-keV γ rays,
we obtained the half-life of the 29.2-keV state, which isconsistent with that obtained from our synchrotron excitation of 229 Th (82(4) ps).3) These coincidences withthe previous results indicate that our experiments anddata analysis were correctly performed. The half-life of
the 97.1-keV state was obtained from γ rays of 54.7 and97.1 keV detected in coincidence with 4729-keV alphaparticles. The obtained half-life was seemingly shorter
than the reference value (147(12) ps).4) This may be because our measurement has better and time resolutions
than the previous measurement.4)
We could clearly observe the peak of 66.1-keV γ rays
by gating the γ-ray spectrum with α particles of approximately 4664 keV, which allowed us to obtain the half-lifeof the 163.2-keV state for the first time. We will continue detailed analysis to precisely determine each halflife and discuss the nuclear properties of 229 Th based on
the half-lives determined in this study.
References

1) G. A. Leander et al., Nucl. Phys. A 413, 375 (1984).
2) B. Seiferle et al., Nature 573, 243 (2019).
3) T. Masuda et al., Nature 573, 238 (2019).
4) H. Ton et al., Nucl. Phys. A 155, 245 (1970).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Mass measurements of 252 Cf fission fragments via MRTOF-MS
S. Kimura,∗1 M. Wada,∗2 H. Haba,∗1 S. Ishizawa,∗1,∗3,∗2 T. Niwase,∗1,∗4,∗2 M. Rosenbusch,∗2 and P. Schury∗2
for the SHE-Mass Collaboration

Z

60

2 2 2
1 1 1
1 1
1

55

2
2 2
2
2 2
1 1
1 1
1

2
2 2
2
2 2
2 2
1

2
2
2
2
2

2
2
2
2
2

2
2
2
2
2
2

2 2
2
2 2
2 2
2 2
2 2

2 2 2
2 2 2
2 2 2
2

50
80

85

90
N

95

100

10

5

10

6

10

7

10

8

10

9

10

10

10

11

∗2
∗3
∗4

240 laps
152Pr++Counts / 3.2 ns bin

140
120
100
80
60

152Ce++

07277400

7277600
TOF ( ns )Counts / 3.2 ns bin

7277800

241 laps

152Nd++

50

152Pr++

40
30
20

152Ce++

10
07307200

7307400
TOF ( ns )Fig. 2. TOF spectra of doubly charged A = 152 series. The
red line indicates a fit obtained using an exponentialGaussian hybrid function.3)
1.5

Exp(AME16)
FRDM12
KTUY05HFB24
WS4Present study

1
0.5
0
-0.5
-1
-1.5
84

86

88

90
92
94
Neutron number

96

98

100

Fig. 3. Neutron-number dependence of cerium-isotope
mass excess. Each line indicates a theoretical prediction. In the region of N > 93, the zero line corresponds
to the extrapolated masses listed in AME16.

determined by a single reference method.3) A typicalmeasurement achieved a relative precision of δm/m ∼10−7 . Figure 2 shows TOF spectra of the doubly
charged A = 152 series with diﬀerent numbers of laps.
As the relative position and intensity remain constantwhen the number of laps is varied, we can infer that thethree peaks are isobaric. In this case, 152 Nd was used
as a mass reference, and we experimentally determine
the mass of 152 Ce for the ﬁrst time. The measured
mass excess of 152 Ce is M E = −58845(61) keV andindicated in Fig. 3 with several theoretical predictions.
This result shows that the ground state of 152 Ce is lessbound than all the predictions listed in Fig. 3.

Fig. 1. Location of the observed isotopes on the nuclear
chart. The numbers, 1 or 2, indicate the observed
charge state. The color bar represents the precisionof experimental mass data taken from the 2016 Atomic
Mass Evaluation (AME16).
∗1

152Nd++

180
160

40
20

Mass Precision

65

220
200

ME-MEAME16 ( MeV )The rapid neutron-capture (r-) process path is governed by the balance between the β − -decay rate andneutron-capture rate. Masses of nuclei involved in the
r-process path play a crucial role in determining theﬁnal isotopic abundance. It is diﬃcult to access the
r-process nuclei due to their locations far from stability; thus, theoretical predictions are needed to obtain the ﬁnal isotopic abundances. However, in theregion where there are no experimental data on nuclear masses, the predicted mass values show a large
variance.1) Thus, accurate and precise mass data ofneutron-rich nuclei are required.
Here, we report mass measurements of the neutronrich nuclei produced by the spontaneous ﬁssion 252 Cf
with multi-reﬂection time-of-ﬂight mass spectroscopy(MRTOF-MS).2) The MRTOF-MS system consistsof a cryogenic gas cell (GC) with a 0.5 µm Mylar
window, an ion transport system having two linear
RF quadrupole traps, and an ejection system to the
MRTOF device. A 350 kBq 252 Cf source (SF: 3.09%)
with 6 µm Ti degrader was installed in front of the GC
window. Throughout the measurements, the GC wascryogenically cooled blow 70 K while the He gas pressure was regulated to maintain a density equivalent to
150 mbar at room temperature.
The measurement results are summarized in Fig. 1.
In the present study, we observed 78 isotopes fromiodine (Z = 53) to europium (Z = 63) in the TOF
spectra. The masses of the observed isotopes wereReferences

1) M. R. Mumpower et al., Prog. Part. Nucl. Phys. 86, 86(2016).
2) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B
335, 39 (2014).
3) Y. Ito et al., Phys. Rev. C 88, 011306(R) (2013).

RIKEN Nishina Center
WNSC, IPNS, KEK
Department of Physics, Yamagata University
Department of Physics, Kyushu University- 52 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

In-gas-cell laser ionization spectroscopy of Os isotopes using
MRTOF-MS at KISS
Y. Hirayama,∗1 H. Choi,∗2 J. Y. Moon,∗3 T. Hashimoto,∗3 M. Mukai,∗4 T. Niwase,∗5 M. Oyaizu,∗1
M. Rosenbusch,∗1 P. Schury,∗1 A. Taniguchi,∗6 M. Wada,∗1 Y. X. Watanabe,∗1 and H. Miyatake∗1
We developed the KEK Isotope Separation System(KISS)1) to study the nuclear properties of neutron-richisotopes with neutron numbers around N = 126. To
study the nuclear structures at KISS, we measured thehyperﬁne structure (HFS) of 194 Os (I π =0+ , T1/2 =6.0 y) and 196 Os (I π = 0+ , T1/2 = 34.9 m) to determine the change in charge radius using the in-gascell laser ionization spectroscopy technique2) assistedby the multi-reﬂection time-of-ﬂight mass spectrograph(MRTOF-MS). The MRTOF-MS installed at KISS cansuccessfully identify isotopes from mass-dependent timeof-ﬂight (TOF) spectra.3)
We measured the HFS of short-lived (T1/2 ∼ 30 min)isotopes by detecting the β- and γ-rays at KISS, and it isdiﬃcult to measure the HFS of isotopes with T1/2 > 1 h
by detecting the decay radiations in a limited beam time.
However, we can eﬃciently measure the HFS of these isotopes through ion counting using the MRTOF-MS without waiting for the radiation decays. Here, we report the
HFS measurement of 194 Os using the MRTOF-MS.
The 194 Os isotopes were produced in multi-nucleon
transfer reactions by using a stable 136 Xe beam (50 pnA)
with an energy of approximately 10 MeV/nucleon impinging on a 198 Pt target (12.5 mg/cm2 , enriched to 91%
with about 3% each of 194, 195, 196 Pt). Singly charged isotopes, produced by the in-gas-cell laser ionization technique, with an energy of 20 keV were extracted from the
KISS gas cell for the HFS measurements. The extracted
isotopes were injected into a helium gas cell for thermalization. Doubly charged ions were primarily producedby the charge exchange reaction with helium atoms in
194

2+

Pt

194

2+

Os

194

2+

Au

Fig. 1. Measured TOF spectrum of 194 Os2+ .
∗1

∗2
∗3
∗4
∗5
∗6

Wako Nuclear Science Center (WNSC), Institute of Particle
and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)
Seoul National University
Institute for Basic Science (IBS)
Department of Physics, University of Tsukuba
Department of Physics, Kyushu University
Institute for Integrated Radiation and Nuclear Science, Kyoto
University (KURNS)

y
r
a

in

im

l
re

backgroundP

Fig. 2. Measured HFS spectrum of 194 Os (I π = 0+ ). Horizontal uncertainty estimated from the accuracy of awavemeter.

the stopping process, and they were extracted from thehelium gas cell. Subsequently, the bunched isotopes were
injected into the MRTOF-MS for particle identiﬁcation.
The details of the MRTOF-MS system are reported inRef. 3).
Figure 1 shows the TOF spectrum of 194 Os2+ measured using the MRTOF-MS at KISS. We can clearly
identify the 194 Os2+ isotope with a contaminant peakof 194 Pt2+ ions, which were emitted through elastic
events from the production target and transported to
the MRTOF-MS as survived ions. By ﬁtting the TOF
spectrum, we can deduce the number of ions extracted
from the KISS gas cell. The HFS spectrum, as shown in
Fig. 2, was obtained by measuring the number of laserionized 194 Os isotopes as a function of the laser wavelength. There appears one resonance peak stemmingfrom one atomic transition of 194 Os due to I π = 0+ .
The constant background (dashed line) in Fig. 2 indicates the contaminant at the 194 Os2+ peak, which corresponds to 194 Au2+ transported as survived ions. The
expected TOF peak position of 194 Au2+ indicated by theblack dotted line in Fig. 1 deviates by about 4 ns fromthe 194 Os2+ peak. To evaluate the extraction yields of
194
Os2+ accurately, we ﬁt the spectrum by omitting the194
Au2+ peak because of the closeness of the peak positions. However, we could clearly deduce the resonancepeak of 194 Os and the amount of 194 Au as the constantbackground, as shown in Fig. 2. From the peak position, we can determine the isotope shift value of 194 Os
to deduce the change in the charge radius and discuss
the nuclear deformation. Further analysis is in progress.
References

1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B412, 11 (2017).
2) Y. Hirayama et al., Phys. Rev. C 96, 014307 (2017).
3) J. Y. Moon et al., in this report.

- 53 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Calibration and simulation of LaBr3 :Ce scintillator for analyzing
8
Li(α, n)11 B-reaction data
Y. Mizoi,∗1,∗2,∗3 H. Baba,∗3 A. Bracco,∗4,∗5 F. Camera,∗4,∗5 S. M. Cha,∗6 K. Y. Chae,∗6 S. Cherubini,∗3,∗7,∗8
H. S. Choi,∗9 N. N. Duy,∗6 T. Fukuda,∗3,∗10 S. Hayakawa,∗2 Y. Hirayama,∗11 N. Imai,∗2 H. Ishiyama,∗3 A. Kim,∗12
D. H. Kim,∗6 N. Kitamura,∗2 S. Kubono,∗2,∗3 M. S. Kwag,∗6 S. Michimasa,∗2 M. Mihara,∗3,∗13 H. Miyatake,∗11
S. Ota,∗2 R. G. Pizzone,∗7 H. Shimizu,∗2,∗3 N. K. Uyen,∗6 R. Wakabayashi,∗3,∗13 Y. X. Watanabe,∗11
O. Wieland,∗4 H. Yamaguchi,∗2 L. Yang,∗2 N. Zhang,∗2,∗14 and Z. C. Zhang∗14
single escape and double escape are consistent with thesimulated ones. By applying the results of our precise
energy calibration, we can proceed to the data analysis
for solving the discrepancies among the previous results.

Energy (keV)

9000
8000

Table 1. Gamma-ray sources used for oﬀ-line calibration andtheir energies.
SourceCs
Am/Be(12 C∗ )Cm/C(16 O∗ )Am/Be+Al
137

Energy (keV)

R² = 0.9999

7000
6000
5000
4000
3000
2000
1000
0
170

190

210

230
TDC channel

250

Fig. 1. Calibration plot obtained by oﬀ-line measurements.

Counts

We performed an experiment1) using LaBr3 :Ce scintillators2) at CRIB in 2018 for investigating controversial large diﬀerences among the previously reported3–9)
cross-section data of the 8 Li(α, n)11 B reaction. In order to resolve the discrepancies among them, it is essential to obtain an accurate γ-ray spectrum of 11 B;
therefore, accurate energy calibration and precise eﬃciency estimation play a crucial role. We performed oﬀline measurements for energy calibration using radiation
sources, as listed in Table 1. Figure 1 presents the calibration plot, in which the horizontal and vertical axes
correspond to the time-to-digital converter (TDC) channel reduced by a charge-to-time converter (QTC) andthe expected γ-ray energy, respectively; the plot shows
suﬃciently good linearity. On-line measurements using
16
N beams were also performed at CRIB. In the studied
reaction, 16 N decays to 16 O∗ , which emits γ-rays with
Eγ = 6130 keV. GEANT4 simulations were also performed for each type of γ-rays. One example is shownin Fig. 2, which is the preliminary result of the γ-ray
energy spectrum of 16 N(βγ). The histogram with error
bars and ﬁlled histogram are measured and simulated
spectra, respectively. The measured peaks of full energy,

30
25
20
15

662
4440
6130
7724

10
5
0

∗1

Center for Physics and Mathematics, Institute for Liberal Arts
and Sciences, Osaka Electro-Communication University∗2 Center for Nuclear Study, the University of Tokyo∗3 RIKEN Nishina Center∗4 INFN - Sezione di Milano∗5 Dipartimento di Fisica dell’Università degli Studi di Milano∗6 Department of Physics, Sungkyunkwan University∗7 INFN - Laboratori Nazionali del Sud (LNS)∗8 Dipartimento di Fisica ed Astronomia, Università di Catania∗9 Department of Physics and Astronomy, Seoul National University∗10 RCNP, Osaka University∗11 Wako Nuclear Science Center (WNSC/IPNS), KEK∗12 Department of Physics, Ewha Womans University∗13 Department of Physics, Osaka University∗14 IMP, Chinese Academy of Science (CAS)- 54 -

4600

4800

5000

5200

5400

5600

5800

6000

6200 6400
Energy (keV)

Fig. 2. Energy spectrum of γ-rays from 16 N(βγ).

References

1) Y. Mizoi et al., RIKEN Accel. Prog. Rep. 52, 58 (2019).
2) A. Gaiz et al., Nucl. Instrum. Methods Phys. Res. A 729,
910 (2013).
3) R. N. Boyd et al., Phys. Rev. Lett. 68, 1283 (1992).
4) X. Gu et al., Phys. Lett. B 343, 31 (1995).
5) Y. Mizoi et al., Phys. Rev. C 62, 065801 (2000).
6) S. Cherubini et al., Eur. Phys. J. 20, 355 (2004).
7) H. Ishiyama et al., Phys. Lett. B 640, 82 (2006).
8) M. La Cognata et al., Phys. Lett. B 664, 157 (2008).
9) S. K. Das et al., Phys. Rev. C 95, 055805 (2017).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Measurement of 25 Al+p resonant elastic scattering relevant to theastrophysical reaction 22 Mg(α, p)25 Al
J. Hu,∗1 H. Yamaguchi,∗2 S. W. Xu,∗1 N. T. Zhang,∗1 S. B. Ma,∗1 L. H. Ru,∗1 E. Q. Liu,∗1 T. Liu,∗1
S. Hayakawa,∗2 L. Yang,∗2 H. Shimizu,∗2 D. Kahl,∗3 C. B. Hamill,∗3 A. Murphy,∗3 J. Su,∗4 X. Fang,∗5 K. Chae,∗6
M. Kwag,∗6 S. Cha,∗6 N. N. Duy,∗6 N. K. Uyen,∗6 D. Kim,∗6 G. Pizzone,∗7 M. L. Cognata,∗7 S. Cherubini,∗7
S. Romano,∗7 A. Tumino,∗7 J. Liang,∗8 A. Psaltis,∗8 M. Sferrazza,∗8 D. H. Kim,∗9 and S. Kubono∗10
Type-I X-ray bursts are the most frequently observed thermonuclear explosions in nature.1) They occur on the surface of accreting neutron stars in lowmass X-ray binary systems. The investigation of Xray bursts can help us understand the properties of aneutron star and the underlying physics.
The bursts are driven by the tripe-α reaction, the
αp-process, and the rp-process. After breakout fromthe hot CNO cycle, the nucleosynthesis path is characterized by the αp-process.2) The αp-process is a sequence of α- and proton-induced reactions that transport nuclear material from the CNO cycle toward theregion of heavier proton-rich nuclei.
The X-ray light curve is the main direct observableof X-ray bursts and could be aﬀected signiﬁcantly by
the αp-process. According to a recent sensitivity study
by Cyburt,3) the 22 Mg(α, p)25 Al reaction is thought tobe the most sensitive one during the αp-process andmay have a prominent impact on the burst light curve.
However, with scarce experimental information on thisreaction, the reaction rate in the calculations of X-ray
bursts is estimated based on statistical models.
A measurement of 25 Al+p resonant elastic scattering has been performed to experimentally examine the22
Mg(α, p)25 Al reaction rates. The experiment was
performed using the CNS radioactive ion beam separator (CRIB),4) installed by the Center for Nuclear Study(CNS), University of Tokyo, in the RIKEN Accelerator
Research Facility. A primary beam of 24 Mg8+ was accelerated up to 8.0 MeV/nucleon by the AVF cyclotron
with an average intensity of 1 eµA. The primary beam
bombarded a liquid-nitrogen-cooled D2 gas target to
produce a secondary 25 Al beam via the 24 Mg(d, n)25 Al
reaction in inverse kinematics. The 25 Al beam wasseparated by the CRIB separator. The 25 Al beam,with an average energy of 5.68 MeV/nucleon and an
average intensity of 2.0 × 105 pps, was then delivered to the F3 experimental chamber, where it bom-

50 cm

26 cm

23 cm


MCP (CH 2) n

PPAC
25

Al

23°

targetp

Fig. 1. Schematic diagram (top view) of the experimental
setup at the F3 chamber.

barded a 13.95-mg/cm2 -thick (CH2 )n target and a
18.02-mg/cm2 -thick C target in which the beam wasstopped. The C target was used to evaluate the background contributions. After passing through a Wienﬁlter, the 25 Al beam purity can be up to 80%.
The setup at the F3 experimental chamber is shownin Fig. 1. A parallel-plate avalanche counter (PPAC)
and a micro channel plate (MCP) were used for measuring the time and position information of the beam
particles. The beam particles were identiﬁed in an
event-by-event mode using the abscissa of MCP and
the time of ﬂight between MCP and the RF signal
provided by the cyclotron.
The recoiling light particles from the 25 Al+p reaction were measured using three sets of Si telescopes ataverage angles of θlab ≈ 0◦ , 20◦ , and 23◦ , respectively.
Each telescope consisted of a 65-µm-thick double-sidestrip (16 × 16 strips) silicon detector and two 1500µm-thick pad detectors. The recoiling particles wereclearly identiﬁed using the ∆E-E method. An array often NaI(Tl) detectors was mounted directly above thetarget and used to detect the γ rays from the decayof the excited states in 25 Al. The data analysis is inprogress.
References

1) W. H. G. Lewin, J. V. Paradijs, R. E. Taam, Space
Science Reviews 62, 223 (1993).
2) R. K. Wallace, S. E. Woosley, Astrophys. J. Suppl. 45,
389 (1981).
3) R. H. Cyburt et al., Astrophys. J. Suppl. 830, 55 (2016).
4) Y. Yanagisawa et al., Nucl. Instrum. Methods Phys.
Res. A 539, 74 (2005).

∗1

Institute of Modern Physics, Chinese Academy of Sciences
Center for Nuclear Study, University of Tokyo∗3 School of Physics & Astronomy, University of Edinburgh∗4 College of Nuclear Science and Technology, Beijing Normal
University∗5 School of Physics, Sun Yet-sen University∗6 Department of Physics, Sungkyunkwan University∗7 INFN-LNS, Laboratori Nazionali del Sud∗8 Department of Physics & Astronomy, McMaster University∗9 Department of Physics, Ewha Womans University∗10 RIKEN Nishina Center∗2- 55 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

26

Si beam production and thermal durability test of gas target window

M. J. Kim,∗1 K. Y. Chae,∗1 S. Hayakawa,∗2 S. M. Cha,∗1 N. N. Duy,∗1 G. M. Gu,∗1 M. S. Kwag,∗1 N. R. Ma,∗2
N. K. Uyen,∗1 H. Shimizu,∗2 and H. Yamaguchi∗2∗1∗2Department of Physics, Sungkyunkwan University
Center for Nuclear Study, University of Tokyo- 56 -

100

90

Time of Flight (ns)The study of the αp process is important for understanding nucleosynthesis in x-ray burst. The process,which is composed of alternating (α, p) and (p, γ) reactions, is considered the bridge between the CNO cycle and rp process. Owing to technical issues, mostof the astrophysical (α, p) reactions on radioactive isotopes are less understood experimentally, including the26
Si(α, p)29 P reaction. The energy levels of 30 S fallingin the Gamow window of the reaction at x-ray burst
temperatures (T = 1 − 3 GK, Ex = 10 − 14 MeV) are
crucial for the 26 Si(α, p)29 P reaction rate. Many energy
levels were identified through previous works,1) but the
spins of levels above Ex = 10 MeV are not constrained inmany cases. Additionally, no energy levels above Ex =12.4 MeV have been measured so far. Thus, we thus plan
to measure the 26 Si(α, α)26 Si elastic resonant scattering.
We simultaneously expect that the 26 Si(α, p)29 P reaction is also directly observable, which requires a rather
high-intensity 26 Si beam. The primary beam intensity
is, however, limited to only approximately 200 pnA toprevent the deposited heat from breaking the F0 gas target window (Havar foil). Therefore, other types of foils
were tested during the beam time.
We took 1.5 days out of the approved 12 days of
beamtime to test the 26 Si beam production at the Center for Nuclear Study Radioactive Ion Beam Separator (CRIB)2) of the University of Tokyo in December
2019. A primary beam of 24 Mg8+ was accelerated by
the AVF cyclotron at 7.5 MeV/nucleon and with a maximum intensity of 400 pnA, bombarding the cryogenic
3
He gas target of 0.94 mg/cm2 . The 3 He gas was confined with windows of 3-µm-thick Ti foil (ϕ = 20 mm),which has a lower thickness and higher heat conductivity than the commonly used Havar foil, with the expectation of a higher injecting beam intensity. The
beam of the radioactive isotope 26 Si was produced by the3
He(24 Mg, 26 Si)n reaction. We installed a 0.2-mg/cm2 thick carbon foil as a charge stripper to obtain a higher
population of the highest charge state 26 Si14+ . The magnetic rigidity was set to 0.61208 Tm to select the desired
beam energy of 5.2 MeV/nucleon. The voltage of thesubsequent Wien filter was ±85.5 kV. A 26 Si purity of
59% and a beam intensity of about 4.7 × 104 particles
per second were achieved at the F3 focal plane, which aremuch higher than those of the previously produced 26 Si
beam at CRIB.3) The particle identification plot at F3
is shown in Fig. 1. This improvement may be attributed
to the higher primary beam intensity, the thinner gas
target window foil, the newly installed charge stripper,
and the higher Wien filter voltage.
We also investigated the thermal durability of other

26

Si14+

80

70

25

Al13+

60

50
-20

0

20

F3 PPAC a - X position (mm)Fig. 1. Particle identification spectrum obtained at the F3
focal plane. The 26 Si beam is clearly separated from otherbeam particles.

materials of the gas target window through primarybeam injection. We installed Mo (100% molybdenum,
thickness: 3 µm, thermal conductivity: 138 W/m/K,
melting point: 2896 K), Ti (100% titanium, thickness:
3 µm, thermal conductivity: 21.9 W/m/K, melting
point: 1941 K), Havar (thickness: 2.5 µm, thermal conductivity: 13 W/m/K, melting point: 1753 K) and CuBe
(98% copper, 2% beryllium, thickness: 3 µm, thermal
conductivity: 105 W/m/K, melting point: 1143 K) foils
held by copper frames on a rotating wheel4) in the F0
chamber. The temperature of each window was monitored by thermography. The foils were exposed toa 24 Mg8+ primary beam up to an intensity of about2800 enA, at which all the foils were pin-holed on the
beam-spot position but the Mo foil endured. The typical beam size is measured to be about 2 mm. We also
tested those foils mounted on the gas-filled target cellwith liquid-nitrogen cooling-except the CuBe foil. We
exposed the Ti foil to a 2600 enA 24 Mg8+ beam and theHavar and Mo foils to 1800 enA beams. The result showsthat only the Mo foil resisted breakage, suggesting that itis the most durable material. This is consistent with thehighest thermal conductivity and melting point among
the tested materials. We will determine the upper limitof the heat deposition rate through further investigation.
We anticipate that a higher intensity of the secondary
26
Si beam could be realized when Mo foils are used at
the F0 gas cell.
References

1) S. Almaraz-calderon et al., Phys. Rev. C 86, 065805 (2012).
2) Y. Yanagisawa et al., Nucl. Instrum. Method Phys. Res.
A 539, 74 (2005).
3) H. S. Jung et al., Phys. Rev. C 85, 045802 (2012).
4) D. Kahl, Master’s thesis, McMaster University (2008).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Production of a high-intensity francium ion beam
for the measurement of the electron electric dipole moment
H. Nagahama,∗1 K. Nakamura,∗1 N. Ozawa,∗1 Y. Kotaka,∗1 H. Haba,∗2 T. Hayamizu,∗2 M. Ohtsuka,∗2,∗3
K. S. Tanaka,∗4 H. Ueno,∗2 Y. Ichikawa,∗2 and Y. Sakemi∗1
The striking imbalance between matter and antimatter observed in the universe is known to be one of
the biggest mysteries in modern physics. For decades,
physicists have been attempting to investigate CP (C:charge conjugation, P: parity transformation) violations for diﬀerent physical systems, which could lead tothe discovery of the fundamental reasons for this mystery. One of these intriguing systems is the electric
dipole moment of an electron (eEDM). The existenceof an absolute value of the eEDM implies that CP symmetry has been violated. At the same time, this would
also reveal the existence of a new theory beyond thestandard model of particle physics.
Since the eEDM is expected to be small,1) it is necessary to adopt a system that enhances the eEDM toa suﬃciently large value. For this purpose, we havechosen francium. Francium has an eEDM enhancement factor of approximately 103 , which is known tobe the largest among any ground-state atom.2) The
ideal environment for Ramsey spectroscopy to measure the eEDM using francium atom is one in which alarge amount of francium atoms are trapped in a tiny
volume where the interactions with other particles arehighly suppressed. To this end, we are planning todevelop a three-dimensional optical lattice to conﬁnelaser-cooled francium atoms.
In this study, we constructed a surface ionizer to create a high-intensity francium ion beam. The surface
ionizer consists of a vacuum chamber, a gold target, deﬂection electrodes, and an infrared radiation heater, as
shown in Fig. 1. An 18 O6+ beam (6.28 MeV/nucleon)
provided by the AVF cyclotron in RIKEN RIBF will beirradiated on the gold target to induce the following fusion reactions inside the gold: 197 Au(18 O, xn)215−x Fr.
By heating up the target using the infrared heater, thethermal diﬀusion process of the franciums will occur,and some fractions will reach the surface. Most of the
franciums at the surface will be ionized according to
the Saha-Langmuir equation3) and, subsequently, thermally released into the vacuum. Since high voltages
are applied to the target (∼1000 V) as well as to thedeﬂection electrodes (∼930 V), the thermal francium
ions will experience the electric-ﬁeld gradient and betransported as a secondary beam (∼1 keV), which will
be guided at an angle of 45◦ with respect to the 18 O6+
beam. The francium ion beam generated will ﬁnally
∗1
∗2
∗3
∗4

2 EHDP 

0&366'
FKDPEHU)UEHDP'HIOHFWLRQ
HOHFWURGHV 9

,QIUDUHGUDGLDWLRQKHDWHU :*ROGWDUJHW
9Fig. 1. Schematic of the experimental apparatus to produce a high-intensity francium ion beam.

be monitored using a beam diagnostic system. The
beam diagnostic system consists of a micro-channel
plate (MCP) to monitor the beam’s characteristics anda silicon semiconducting detector (SSD) to observe α
radiation caused by the α decay of the franciums. An
α radiation source (Am) is placed near the SSD to calibrate the energy of the α radiation.
In September 2019, we constructed this experimental apparatus and performed an oﬄine test. During theoﬄine test, we heated up the target to 400 ∼ 800◦ C using the infrared heater and thermally ionized particles
already existing on the surface. These ionized particles
were monitored by the MCP, which allowed us to optimise the voltages applied to the target and the deﬂection electrodes. We have conﬁrmed that the optimised
voltages are consistent with our previous simulation using SIMION 8.1. After the oﬄine test, we performed
online experiments on October 25, 2019 and November 22, 2019. Through data analysis, we veriﬁed that
we had succeeded in producing a 210 Fr+ beam with anintensity of 1.3 × 106 /s.
References

1) M. S. Safronova et al., Rev. Mod. Phys. 90, 025008(2018).
2) J. S. M. Geinges, V. V. Flambaum, Phys. Rep. 397, 63(2004).
3) M. J. Dresser, J. Appl. Phys. 39, 338 (1968).

Center for Nuclear Study, the University of Tokyo
RIKEN Nishina Center
Waseda University Honjo Senior High School
Cyclotron and Radioisotope Center, Tohoku University- 57 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Development of β-NMR with spin-aligned beam
H. Nishibata,∗1,∗2 A. Gladkov,∗1 H. Ueno,∗1 Y. Ichikawa,∗1 A. Takamine,∗1 H. Yamazaki,∗1 M. Tajima,∗1
K. Kawata,∗1,∗3 M. Mihara,∗4 T. Sato,∗1 K. Doi,∗1,∗5 W. Kobayashi,∗1,∗5 M. Sanjo,∗1,∗5 T. Asakawa,∗1,∗5
Y. Sasaki,∗1,∗5 T. Yada,∗1∗5 and K. Asahi∗1
Nuclear electromagnetic moments, namely magnetic
dipole (µ) and electric quadruple (Q) moments, are oneof the most sensitive probes to address a single-particle
conﬁguration and nuclear deformation, respectively.
So far, nuclear moments for ground states have beenmeasured by the method of β-ray-detected nuclear
magnetic resonance (β-NMR) combined with a spinpolarized radioactive beam. However, it is diﬃcult
to apply β-NMR to far-unstable nuclei produced by
BigRIPS because the spin polarization is signiﬁcantly
reduced for reactions with the removal of many nucleons and/or with a beam energy >100 MeV/nucleon. In
order to overcome this diﬃculty, we have been developing a new method that combines the β-NMR techniqueand highly spin-aligned beam production with the twostep fragmentation method by using BigRIPS.1) This
report presents the recent results of a demonstration
experiment using spin-aligned 13 B (T1/2 = 17.3 ms, I π= 3/2− ) with the known ground-state µ and Q moments.3)
The experiment was performed at the Heavy Ion
Medical Accelerator in Chiba (HIMAC). A primary
15
N beam with an energy of 100 MeV/nucleon was accelerated by the synchrotron. The beam irradiation
time was 20 ms in every 3.3 s. A radioactive 13 B beam
was produced by the two-proton-removal reaction of15
N with a 1-mm-thick Be target, which was locatedat the entrance of the secondary beamline SB2. The
13
B beam was separated by two dipole magnets and awedge-type energy degrader (3-mm thickness, 6◦ angle) at the dispersive focal plane F1. The spin alignment was obtained by selecting a moment oﬀ the center of the momentum distribution by −4–−3%. Subsequently, the spin-aligned 13 B beam was delivered tothe end of the beamline F3, where the β-NMR apparatus is located, and was implanted to a TiO2 single
crystal.
Since the Q moment of the implanted 13 B interacts
with an electric ﬁled gradient at the implantation site
in the crystal and causes unequal Zeeman splitting between the individual sub-levels, a partial spin reversal using the adiabatic fast passage (AFP) method2)
becomes possible and convert the spin alignment of
the implanted 13 B into the spin polarization. Consequently, the angular distribution of the emitted β rays
becomes anisotropic. For the AFP method, a static
∗1
∗2
∗3
∗4
∗5

Fig. 1. Obtained NMR spectrum for spin-aligned 13 B.
The ordinate of this spectrum shows the double ratio
RRFon /RRFoﬀ , where RRFon (RRFoﬀ ) is the ratio of theβ-ray counts detected by the 0◦ and 180◦ telescopeswith (without) the oscillating magnetic field. The dotted line is the spectrum expected from the literature
values of µ = +3.1778(5) µN and Q = +36.6(8) mb3)
assuming a spin alignment of 4.5%.

magnetic ﬁeld of 0.2 T was applied to the crystal perpendicular to the beam axis in the horizontal plane,
and an oscillating magnetic ﬁeld was applied by a pairof coils perpendicular to the static magnetic ﬁeld. The
β rays from the β decay of 13 B were detected by twotelescopes placed at 0◦ and 180◦ with respect to thedirection of the static magnetic ﬁeld. Each telescopeconsists of two 1.0-mm-thick plastic scintillators.
Figure 1 shows the obtained NMR spectrum forspin-aligned 13 B. The resonances were observed at3067 ± 84 kHz and 3394 ± 84 kHz, which correspondto the transitions between the Zeeman sub-levels withm = −3/2 and −1/2, +1/2, and +3/2, respectively.
From these values, the moments of 13 Bg.s. were deduced to be |µ| = 3.18 (9) µN and |Q| = 36(9) mb,
which are consistent with the literature values of µ
= +3.1778(5) µN and Q = +36.6(8) mb.3) We havesuccessfully demonstrated our new method of β-NMR
with a spin-aligned beam.
References

1) Y. Ichikawa et al., Nat. Phys. 8, 918 (2012).
2) A. Abragam, The Principles of Nuclear Magnetism,(Clarendon, Oxford, 1961).
3) T. Nagatomo et al., Nucl. Phys. A 746, 509c (2004).

RIKEN Nishina Center
Department of Physics, Kyushu University
Center for Nuclear Study, University of Tokyo
Department of Physics, Osaka University
Department of Physics, Hosei University- 58 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Production of isomers around 52 Fe nucleus via projectile fragmentation
K. Kawata,∗1,∗2 S. Ota,∗2 J. Zenihiro,∗1 C. Iwamoto,∗2 N. Kitamura,∗2 H. Sakai,∗2 S. Masuoka,∗2
S. Michimasa,∗2 K. Yako,∗2 T. Harada,∗2 H. Nishibata,∗2 R. Tsunoda,∗2 N. Imai,∗2 J. Hwang,∗2 N. Zhang,∗4 and
F. Endo∗5
The nuclear responses of isomeric high-spin states
are attractive topics. A recent theoretical study on
the spin-isospin response of the 12+ isomeric state in52
Fe showed that the widths of the GT strength distributions from the ground and isomeric states may differ from each other due to the diﬀerent collectivities,1)
which may call for the modiﬁcation of a simple Brink
hypothesis. To perform nuclear reactions on such isomers, isomeric nuclear beams should be prepared since
the isomers are still short-lived nuclei.
Projectile fragmentation is a popular method to produce short-lived nuclei. In order to prepare the isomerbeam, it is necessary to understand the production
mechanism of isomers through the projectile fragmentation process. We studied the isomer ratios in thevicinity of 52 Fe as a function of the linear momentum
transfer. Although the ratios are conventionally described by a classical model assuming the contributionof the angular momentum transfers during the projectile fragmentation process,2) it is still not clear how theangular momentum is transferred to the fragmented
particles. To learn the role of the angular momentum
transfer, we studied not only the isomer ratio but also
the momentum distribution of the isomeric state of
the fragmentation process. In this paper, we report a
new systematic measurement of production cross sections of the isomers 52 Fe(12+ ),53 Fe(19/2− ), 54 Co(7+ ),and 54 Fe(10+ ) by primary beams of 58 Ni(0+ ) and59
Co(7/2− ).

Fig. 2. Isomer ratio of 52 Fe(12+ ). Red triangles show theresult from the 59 Co(7/2− ) beam, and the blue squares
show the result from the 58 Ni(0+ ) beam.

The experiment was performed at the SB2 course
in HIMAC, a synchrotron facility in Chiba. Figure 1
shows the experimental setup at the SB2 course. The
primary beams of 58 Ni and 59 Co at 350 MeV/nucleon
bombarded a 14-mm-thick 9 Be production target. The
fragments are separated and momentum analyzed bya fragment separator consisting of two dipole magnets
and quadrupole magnets. In order to obtain isomerratios, the number of fragments and γ rays from theisomers were counted. A Xe scintillator was used forcounting the fragment, and four Ge detectors were used
for detecting γ rays. The isomer ratio of a certain
fragment nucleus is the ratio of the number of emitted
gamma rays obtained after correcting for the eﬃciency
to the number of fragments.
Plastic
When the velocity of the fragment is the same as
Δp
Scintillator
thatof the projectile, no momentum is transferred toF2
the fragment.
SEM target D1
Plastic
EnergyFigure 2 shows the preliminary result of the isomer
slit
D2
degraderwedge
ratio of 52 Fe(12+ ). The momentum-transfer dependegrader slit
dence of the isomer ratio is clearly observed. The
59−
Xe
Ge*4 isomer ratio with the Co(7/2 ) beam at each moΔEcounter PPAC
mentum is larger than that with the 58 Ni(0+ ) beam.
It is inferred that the initial angular momentum of the
projectile has a signiﬁcant eﬀect on isomer production.
Fig. 1. Experimental setup in the SB2 course (16H362).
The data analysis is ongoing. The diﬀerence beThe number of primary beams was counted by a secondary emission monitor (SEM), which consists of atween the momentum distributions of isomers and nonthin Cu film. We identified the fragment by using theisomers will be investigated in order to clarify the role
ToF-∆E method. ToF was measured from F2 to F3,of angular momentum transfer from the viewpoint ofand ∆E was measured by a Xe scintillation detector.
the correlation between the linear momentum transfers
The number of isomers was counted by a Ge detector.
and angular momentum transfers.
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo
Toho Universicity
Institute of Modern Physics
Tohoku University

References

1) H. Z. Liang et al., Phys. Rev. C 98, 014311 (2018).
2) W. -D. Schmidt et al., Z. Phys. A 350, 215 (1994).

- 59 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

79

Se(n, γ)80 Se reaction cross section through 77, 79 Se(d, p)78, 80 Se
reactions

N. Imai,∗1 M. Dozono,∗1 S. Michimasa,∗1 T. Sumikama,∗2 S. Ota,∗1 S. Hayakawa,∗1 K. Iribe,∗2,∗3 C. Iwamoto,∗1
S. Kawase,∗4 K. Kawata,∗1,∗2 N. Kitamura,∗1 S. Masuoka,∗1 K. Nakano,∗4 P. Schrock,∗1 D. Suzuki,∗2
R. Tsunoda,∗1 K. Wimmer,∗2,∗5 D. S. Ahn,∗2 O. Beliuskina,∗1 N. Chiga,∗2 N. Fukuda,∗2 E. Ideguchi,∗2,∗6
K. Kusaka,∗2 H. Miki,∗2,∗7 H. Miyatake,∗8 D. Nagae,∗2 M. Nakano,∗2,∗9 S. Ohmika,∗2 M. Ohtake,∗2 H. Otsu,∗2
H. J. Ong,∗2,∗6 S. Sato,∗2,∗9 H. Shimizu,∗1 Y. Shimizu,∗2 H. Sakurai,∗2,∗5 X. Sun,∗2 H. Suzuki,∗2 M. Takaki,∗1
H. Takeda,∗2 S. Takeuchi,∗2,∗7 T. Teranishi,∗2,∗3 Y. Watanabe,∗4 Y. X. Watanabe,∗8 H. Yamada,∗2,∗7
H. Yamaguchi,∗1 L. Yang,∗1 R. Yanagihara,∗6 K. Yoshida,∗2 Y. Yanagisawa,∗2 and S. Shimoura1
Se is one of the long-lived ﬁssion products (LLFPs)
of nuclear waste. To design a facility to transmute thenucleus, a neutron-capture cross section on the nucleus
was conceptualized. However, because both the neutronand LLFPs are unstable, the measurement of neutroninduced cross section is quite challenging. Alternatively,
the reaction cross section can be indirectly determinedthrough a surrogate reaction.
It is generally accepted that the (n, γ) cross section
is composed of two parts: the formation of a compoundstate and the subsequent decay. The ﬁrst term can becalculated using optical-model potentials with global parameter sets. In contrast, theoretical estimates of thesecond process is quite challenging owing to its high level
density and complicated decay scheme, and it needs tobe evaluated experimentally.1) The present work aims
to determine the γ emission probability, Pγ , as a function of the excitation energy from the unbound states of80
Se populated by the (d, p) reaction. In the surrogate
method, the Pγ from the transfer reaction is used to determine the (n, γ) cross section. However, it is known
that a mismatch in the angular-momentum transfer between the transfer reaction and capture reaction leads
to a large cross section. To compensate for the mismatch, a surrogate ratio method is often used, where the(n, γ) cross section of interest is normalized using a pairof (n, γ) and transfer reactions of the neighboring nucleus. We deduce the 79 Se(n, γ)80 Se reaction by employing cross sections of 77 Se(n, γ)78 Se2) and 77 Se(d, p)78 Se
reaction.
The experiment was performed using the OEDO beam
line3) as one of the ﬁrst physics experiments. 77, 79 Se
beams produced by BigRIPS were energy-degraded at
F5, and the beam was spatially focused on a 4-mg/cm2
thick polyethylene deuteride target by OEDO. The beamenergy was adjusted to 20 MeV/nucleon at the target.
The recoiled particles were identiﬁed by employing a six∗1
∗2
∗3
∗4
∗5

∗6
∗7
∗8
∗9

Range (arb. unit)

79

Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center
Department of Physics, Kyushu Univ.
Department of Advanced Energy Engineering Science, Kyushu
Univ.
Department of Physics, Univ. of Tokyo
RCNP, Osaka University
Department of Physics, Tokyo Insititute of Technology
WNSC, IPNS, KEK
Department of Physics, Rikkyo University- 60 -

12
640

(a)

10

620

8

600

6

580

4

560

2
2.3

2.35

2.4

2.45

2.5

0

A/Q

Fig. 1. Mass of the outgoing reaction redisue as a functionof their A/Q measured at the S1 focal plane. The events
circled were 80 Se34+, 33+, 32+ , respectively. See the text
for details.

SSD-CsI(Tl) array called TiNA, which covered an angular range of 100◦ –150◦ in the laboratory frame. The
excitation energies of the state populated in 78 Se (80 Se)
were determined using TiNA and the incident beam momentum. The momenta of the outgoing nuclei were analyzed by the ﬁrst half of the SHARAQ spectrometer.
In the correlation between the excitation energy andthe mass-to-charge ratio (A/Q), which we presented in
the last report, 80 Se33+ (A/Q = 2.42) was not clearly
separated from 78 Se32+ (A/Q = 2.44). However, inFig. 1, which presents the mass as a function of the A/Q
ratio of 80 Se, they are separated well. Here, the mass wasdeduced from the analysis of the Bragg curve in the ionization chamber installed at the SHARAQ focal plane.
Analysis has almost been ﬁnalized. The manuscript will
be submitted soon.
This work was funded by the ImPACT Program ofCouncil for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
References

1) J. E. Escher et al., Rev. Mod. Phys. 84, 353 (2012).
2) S. Kawada, M. Igashira, T. Katabuchi, M. Mizumoto, J.
Nucl. Sci. Tech. 47, 643 (2010).
3) S. Michimasa et al., Prog. Theor. Exp. Phys. 2019,
043D01 (2019).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Production-cross-section measurement and new-isotope search for very
neutron-deficient RIs produced from 78 Kr beam at 345 MeV/nucleon by
BigRIPS separator
H. Suzuki,∗1 N. Fukuda,∗1 H. Takeda,∗1 Y. Shimizu,∗1 D. S. Ahn,∗1 T. Komatsubara,∗1 N. Inabe,∗1 K. Kusaka,∗1
Y. Yanagisawa,∗1 M. Ohtake,∗1 H. Sato,∗1 and K. Yoshida∗1∗1

Production cross section (mb)

102
10

(a)

0

Ti

45

50

Ge

Zn

Ni

Fe

Cr

Se

Kr

10-2
10-4
10-6
10-8

10-10
10-12
35

102

Production cross section (mb)

We performed production-cross-section measurements
and new-isotope searches around the proton drip-linewith the atomic numbers Z = 22−30.
Protonrich radioactive isotopes (RIs) were produced by the
projectile fragmentation of a 270-pnA 78 Kr beam at
345 MeV/nucleon impinged on a 5-mm-thick Be production target in the BigRIPS separator.1) Particle identiﬁcation based on the TOF-Bρ-∆E method2) was performed in the second stage of BigRIPS. The production
rates and momentum distirubions of the RIs were measured.
The production cross sections were deduced from themeasured production rates and their transmission eﬃciencies in BigRIPS, which were simulated with LISE++
calculation code.3,4) In the LISE++ simulation, a parameter “coef,” which controls the slopes of exponential
low-momentum tails in the momentum distribution of
the RIs, was adjusted to reproduce the measured distribution. The tails observed in the experiments fell oﬀ
faster than those calculated using LISE++ with the original parametrization. Momentum-peak shifts between
the simulations and experimantal results were also taken
into account in the calculation by tuning the Bρ values ofthe dipoles. The tuned Bρ values in the calculation weretypically ∼1% higher than the experimental ones. The
parameters of the angular distribution were not changedin the code.
Figure 1 shows the production cross sections of RIs obtained in the 78 Kr-beam campaign in 2019 (open circles)
and 2015 (open squares) with measurements by B. Blank
et al.5) (ﬁlled triangles). The solid lines in Fig. 1 show
the cross sections predicted from the empirical formula
EPAX3.1a.6) The measured cross sections of RIs with awide range of Z are fairly well reproduced by EPAX3.1a,
except in a region around the proton drip-line. There
are discrepancies between the cross sections measured
by B. Blank et al.5) and the ones in 2019 for Ti and Cr
isotopes. It may have been caused by insuﬃcient tunings
in the calculation in our preliminary analysis.
No new isotopes were discovered in our measurement
for Cr nor Ti isotopes. From the lack of observationof 41 Cr and 39 Ti and their expected yields, the upper
limits of their half-lives were preliminarily estimated to
be 70 ns and 90 ns, respectively.

RIKEN Nishina Center- 61 -

40

(b)

100

V

55

60

65

70

75

Cu

Ga

As

Br

Mass number

Mn

Co

Rb

10-2
10-4
10-6
10-8
Blank et al.
2015 data (preliminary)2019 data (preliminary)
EPAX3.1a

10-10
10-12
35

40

45

50

55

60

Mass number

65

70

75

Fig. 1. Production cross sections of RIs produced in the 78 Kr+ Be reaction at 345 MeV/nucleon. (a) Results for evenZ isotopes. (b) Results for odd-Z isotopes. Filled triangles, open squares, and open circles show the data measured by Blank et al.,5) data measured in 2015, and datameasured in 2019, respectively. Solid lines show the values predicted using the EPAX3.1a formula.6)

References

1) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
2) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).
3) O. B. Tarasov, D. Bazin, Nucl. Instrum. Methods Phys.
Res. B 266, 4657 (2008) (references therein; LISE++ site,
http://lise.nscl.edu,MichiganStateUniversity).
4) O. B. Tarasov, Nucl. Phys. A 734, 536 (2004).
5) B. Blank et al., Phys. Rev. C 93, 061301(R) (2016).
6) K. Sümmer, Phys. Rev. C 86, 014601 (2012).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Database of radioactive isotope beams produced at the BigRIPS
separator†
Y. Shimizu,∗1 N. Fukuda,∗1 H. Takeda,∗1 H. Suzuki,∗1 D. S. Ahn,∗1 N. Inabe,∗1 K. Kusaka,∗1 M. Ohtake,∗1
Y. Yanagisawa,∗1 K. Yoshida,∗1 T. Sumikama,∗1 and T. Kubo∗1,∗2
Many studies on exotic nuclei far from stability havebeen conducted at the RIKEN RIBF1) since 2007, taking advantage of the high intensity and large isotope variety of RI beams produced by the superconducting inﬂight separator BigRIPS.2) Neutron-rich RI beams in avery wide range of the nuclear chart have been produced
utilizing the in-ﬂight ﬁssion of a 238 U beam and the
projectile fragmentation of 18 O, 48 Ca, and 70 Zn beams.
Furthermore, a wide range of proton-rich RI beams havealso been produced utilizing the projectile fragmentation of 78 Kr and 124 Xe beams. The systematically measured production cross sections and other related data
are important to provide accurate production-yield information for planning rare-isotope experiments and to
improve models and formulae to predict the cross section. Therefore, we have organized the data concerning
the RI beam production and constructed a database tocompile them.
The measured production cross sections and yields
have been registered in the RI-beam database,3) alongwith other data sets such as the setting of the BigRIPS
separator and particle-identiﬁcation information. We
constructed such a relational database based on Microsoft Access 2010. Table 1 summaraizes the structureof the database, which consisits of ﬁve tables named“settings,” “yields,” “isomers,” “experiments,” and “papers.”
The graphical user interface of the RI-beam database
was developed as a web application using PHP. As illustrated in Fig. 1, the web interface of the RI-beam
database graphically represents a nuclear chart basedon the KTUY05 formula.4) In the nuclear chart, RI
Table 1. Structure of RI-beam database system as of December 2018.
table
settings

contents
settings_id, experimental conditions (beam,target, degraders, slit openings, Bρs, detectors)
yields
RI, yield, cross section, settings_id
isomers
RI, γ-ray energy, half-life, intensity, level
energy, spectrum of γ-ray energy
experiments proposal number, spokesperson, date,beam, course, delivered RIs
paperstitle, doi, first author, delivered RIs†∗1∗2

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 463, 158 (2020)
RIKEN Nishina Center
Facility for Rare Isotope Beams- 62 -

Fig. 1. Web interface. Cyan and yellow indicate nuclei
and new isotopes produced at the BigRIPS separator, respectively. Pink indicates the nuclei predictedby KTUY05.4) The production cross section and production yield for a nucleus of interest can be accessed
through the hyperlinked site.

beams produced with the BigRIPS separator are indicated by red letters. The production cross section andproduction yield for a nucleus of interest can be accessed through the hyperlinked site.
The RI-beam database and its web interface allow
eﬃcient RI-beam production at the BigRIPS separator. The database stores the RI-beam and related information obtained for more than 1,600 RI beams produced using BigRIPS. This system is a powerful tool
for planning RI-beam production procedures, optimizing BigRIPS settings, and implementing particle identiﬁcation and isotope separation. However, the present
database system was developed with a focus on the useof the production yields and cross sections measured
under various experimental conditions; currently, otherinformation such as RI beam purity is not included. In
the future, we plan to improve the system so that suchinformation can be stored as well. This would further
aid researchers in designing a more accurate experimental plan.
References

1) Y. Yano, Nucl. Instrum. Methods Phys. Res. B 261, 1009
(2007).
2) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
3) Database of radioactive isotope beams produced at the BigRIPS separator. Available at https://ribeam.riken.
jp/ (Accessed 1 Apr. 2019).
4) H. Koura et al., Prog. Theor. Phys. 113, 305 (2006).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

RI beam production at BigRIPS in 2019
Y. Shimizu,∗1 N. Fukuda,∗1 H. Takeda,∗1 H. Suzuki,∗1 D. S. Ahn,∗1 N. Inabe,∗1 K. Kusaka,∗1 M. Ohtake,∗1
Y. Yanagisawa,∗1 T. Komatsubara,∗1 H. Sato,∗1 K. Yoshida,∗1 and T. Uesaka∗1
The radioactive isotope (RI) beam production at the
BigRIPS fragment separator1) in 2019 is reported here.
Table 1 summarizes the experimental programs thatinvolved the use of the BigRIPS separator during thisperiod and the RI beams produced for each experiment.
In the spring beam time, a 78 Kr beam campaign
was conducted with eight experiments. A 67 Se beam
was delivered to the SAMURAI spectrometer to study
the proton-unbound state of 66 Se relevant to the rpprocess. A PALIS experiment was performed to conﬁrm the practical feasibility using the same settings
as for the 67 Se beam. A 62 Zn beam and, thereafter,a cocktail beam of 62 Ga and 62 Ge were produced tomeasure the Coulomb excitation of the A = 62 isospin
triplets and to extract the B(E2) values as well as proton and isoscalar multipole matrix elements. A 56 Zn
beam was produced to perform the ﬁrst γ-ray spectroscopy of the TZ = −2 nucleus 56 Zn to investigate
the mass dependence of the isospin-breaking eﬀects.
48
Cr and 64 Ge beams were produced to study GamowTeller transitions via the (p, n) reaction on the N = Z
unstable nuclei 48 Cr and 64 Ge. The BigRIPS groupmeasured the production cross sections of the proton-rich nuclei around 54 Zn and 43 Cr regions, and searched
the new isotopes for 37, 38 Ti and 47 Cr.2)
After the 78 Kr beam campaign, a 124 Xe beam campaign was conducted with four experiments. A 101 Sn
beam was produced to measure the energy of the ﬁrst
2+ state in 100 Sn. A 102 Sn beam was produced to
study the E2 transition strength of 102 Sn. An experiment with the DTAS setup was performed to measure
the probability of beta decay to excited states populated in the decay of 100 Sn using a cocktail beam ofnuclei around 100 Sn.
In the autumn beam time, a 238 U beam campaign
was conducted with six experiments. A 132 Sn beam
was produced to study the ground-state properties of132
Sn using proton elastic scattering with the ESPRI
setup. A PALIS experiment was performed to study
the extraction eﬃciency using alpha emitters aroundthe 208 Rn region. A cocktail beam of 127 Sn and 128 Sn
was delivered to F8 for the magnetic moment measurement using the time-diﬀerential perturbed angular distribution method. Three machine studies3–5) were performed to develop the production of the neutron-richnuclei with N = 126, the production of a slowed-down
RI beam using momentum-compressed optics, and theFig. 1. RI beams produced in 2019 and the production yield measured from March 2007 to December
2019 at the BigRIPS separator.
∗1

RIKEN Nishina Center- 63 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

ion optics of the large-acceptance-dispersive mode for
the ZeroDegree spectrometer.
The number of experiments using RI beams at the
BigRIPS separator is tallied in Table 2 for various primary beams in each year. A total of 191 experiments
have been performed so far. Figure 1 shows the RI
beams produced in 2019 at the BigRIPS separator on
the table of nuclides with red squares. The production
yields for 1608 RI beams have been measured fromMarch 2007 to December 2019, and they are indicatedwith cyan squares.

References

1) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
2) H. Suzuki et al., in this report.
3) N. Fukuda et al., in this report.
4) T. Sumikama et al., in this report.
5) H. Takeda et al., in this report.

Table 1. List of experimental programs and RI beams produced at the BigRIPS separator in 2019.
Primary beam (Period)

78Kr
345 MeV/nucleon(Mar. 19 – Apr. 18)

124
Xe
345 MeV/nucleon(May 29 – Jun. 18)U345 MeV/nucleon(Nov. 18 – Dec. 6)
238

Proposal No.
CourseRI beams
67
SAMURAISe, 1H
NP1406-SAMURAI24
67
NP1712-RIBF166-01
PALIS
Se
62
ZeroDegree
Ge/62Ga, 62Zn
NP1712-RIBF151R1
56
ZeroDegree
NP1712-RIBF145R1
Zn/57Zn
54
ZeroDegree
MS-EXP19-01
Zn, 41V#
48
SAMURAINP1612-SAMURAI11R1-01/02
Cr, 64Ge
54,55,56
NP1512-RIBF104R1
ZeroDegree
Zn
47
DA19-01-01
BigRIPS
Co#, 39V#
101
ZeroDegree
NP1612-RIBF146
Sn102
NP1612-RIBF153R1
ZeroDegree
Sn100
NP1612-RIBF147
ZeroDegreeSnPE19-01
BigRIPS132
F12
Sn, 48Ca
NP1512-RIBF79R1
208
Rn
NP1712-RIBF166-02
PALIS
202
Os
MS-EXP19-06
BigRIPS
107
MS-EXP19-04
ZeroDegree
Pd
80
MS-EXP19-05
ZeroDegree
Zn124
NP1712-RIBF157
F8
Ag/125Ag, 127Sn/128Sn#
assumed RI beam for the BigRIPS spectrometer

Table 2. Number of experiments performed using RI beams in each year.
Year

238

U

2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
Total

4
2
3
4
6
4
11
15
13
13
7
6
88

124

Xe

86

Kr

78

Kr

70

Zn

1

4
12

6

1

Ca

4
3
10

2
3
2
1

48

8
14

1

4

1
4

3
4
6
2

6

36

18

O

1
2
6
3

16

O

14

N

3
2

4

He

1

1

- 64 -

1

H

1

1
1

2
3
7
24

2

5

1

3

Yearly
total
5
6
10
14
8
20
9
17
26
22
22
14
18
191

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

First success of RI-beam separation and particle identification for
nuclei with atomic number Z > 82 at RIKEN RI beam factory†
T. Sumikama,∗1 T. Kubo,∗1,∗2 N. Fukuda,∗1 D. S. Ahn,∗1 H. Takeda,∗1 Y. Shimizu,∗1 H. Suzuki,∗1 N. Inabe,∗1
D. Murai,∗1,∗3 H. Sato,∗1 K. Kusaka,∗1 Y. Yanagisawa,∗1 M. Ohtake,∗1 and K. Yoshida∗1

:
D1

Li
Be

50

Full
Be

Li

He
Li H
He

Full

He
Li

82

80
2.43

∗1
∗2
∗3

2.44

2.45

2.46

2.47

2.48

2.49

2.5

2.51

2.52

Fig. 2. Particle-identification plot of the RI beams, which
was obtained by applying software gates of −5 < x <5 mm on the F3 and F7 positions.

He

H Full
He H
Li He
Be Li

82

Fig. 1. RI-beam separation scheme at the first stage of
the BigRIPS separator in the case of a 2-mm-thick aluminum degrader. The purple, green, red, orange, andpink solid lines show the selected RI beams for the
charge-state change ∆QF1 = 0, +1, +2, +3, and +4
at F1, respectively. The blue dashed lines show nuclei
having the same A/Q as 208 Rn with Q = 84.
†

1

208
84+
86Rn122

A/ Q

126

50

10

86

84

238U

Full

H

88

e
e
e
ip
e
-lik i-lik e-lik -lik ll str: L : H 1: H Fu
1
1
:
D
D D1
D

82

102

90

Be

208Rn

Be

92

Z

The separation of heavy RI beams is diﬃcult at
RIKEN RIBF, because the charge state Q of ions frequently changes in certain materials including a wedge
degrader used for the RI-beam separation. In an earlier
study,1) a large amount of in-ﬂight ﬁssion fragments
prevented the good separation of heavy RI beams.
In the present study, the charge-state change in thewedge degrader was taken into consideration in termsof the RI-beam puriﬁcation. We found that a 208 Rn
beam can be well separated from the ﬁssion fragments
when He-like and fully-stripped ions are selected at
the ﬁrst and second dipole magnets, respectively. Figure 1 shows the selected isotopes when an aluminum
degrader with a thickness of 2 mm is used at F1 of the
BigRIPS separator.2) This is an extension of a ﬁgurefor the full-strip ions for both dipole magnets given
in Ref. 3). The ﬁssion fragments with atomic numbers between 25 and 65 are required to have Li-like or
Be-like ions at the ﬁrst dipole. The probabilities of Lilike and Be-like ions for 160
85 Tb was estimated using the

Global code4) to be 4.7 × 10−4 and 1.8 × 10−6 , respectively. Because of these low probabilities, the ﬁssion
fragments are expected to be well eliminated.
An experiment to produce a 208 Rn beam was performed at RIKEN RIBF. The 3-mm-thick beryllium
was used as the production target. The thickness of
the aluminum wedge degraders at F1 and F5 were 2
and 1 mm, respectively. The He-like and fully-stripped
ions were chosen at the ﬁrst and second halves of theﬁrst stage of BigRIPS, respectively. The He-like ionswere chosen at the second stage of BigRIPS. To compare the separated RI beams with those in Fig. 1, awide slit setting of ±20 mm was applied at the achromatic foci F2 and F7. The ﬁssion fragments were nottransported to the second stage of BigRIPS even for
the wide slit. Software gates were applied to the positions measured at F3 and F7 to simulate the RI beams
with a narrow slit setting. Figure 2 shows a particleidentiﬁcation plot with gates of −5 < x < 5 mm at F3
and F7. The purity of 208 Rn reached 25%. Therefore,
RIKEN RIBF is now ready for user experiments in thisregion of the nuclear chart.
References

1) N. Inabe et al., RIKEN Accel. Prog. Rep. 48, 73 (2015).
2) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
3) J. P. Dufour et al., Nucl. Instrum. Methods Phys. Res.
A 248, 267 (1986).
4) C. Scheidenberger et al., Nucl. Instrum. Methods Phys.
Res. B 142, 441 (1998).

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 463, 237 (2020)
RIKEN Nishina Center
FRIB/NSCL, MSU
Department of Physics, Rikkyo University- 65 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 53

Analysis of fake asymmetry for the MTV experiment
F. Goto,∗1,∗2 H. Baba,∗2 J. A. Behr,∗3 T. Kajihara,∗4 H. Kawamura,∗5 M. Kitaguchi,∗1 C. D. P. Levy,∗3
H. Masuda,∗4 Y. Nakaya,∗4 K. Ninomiya,∗4 J. Onishi,∗4 R. Openshaw,∗3 S. Ozaki,∗4 M. Pearson,∗3 Y. Sakamoto,∗4
H. M. Shimizu,∗1 Y. Shimizu,∗4 R. Takenaka,∗4 K. Tamura,∗4 S. Tanaka,∗4 R. Tanuma,∗4 Y. Totsuka,∗4
E. Watanabe,∗4 Y. Yamamoto,∗4 Y. Yamawaki,∗4 M. Yokohashi,∗1 and J. Murata4
The Mott polarimetry for T-Violation (MTV) experiment aims to search for a large time-reversal symmetry
violation (T-violation) in polarized 8 Li β decay. This
experiment was conducted at the TRIUMF Isotope Separator and Accelerator (TRIUMF-ISAC). T-Violation
may arise in triple-vector correlation (R-correlation) inbeta decay. R-correlation causes electron transverse polarization and it can be measured by detecting the angle
symmetry of electron Mott scattering using a cylindrical drift chamber (CDC). Figure 1 shows a schematicof how β rays are detected. A 8 Li beam is stopped at
the beam stopper placed at the center of CDC, and anelectron is emitted. CDC can detect the track of theelectron scattered on an analyzer foil.
The electron emission distribution of β − decay, ω, isexpressed as1)
[

]
⃗
⃗ p⃗e
p⃗e
⟨J⟩
⟨J⟩
×
·
+ . . . . (1)ωdEe dΩe ∝ 1 + R⃗σ ·
+A
J
Ee
J Ee

The deﬁnition of R-correlation can be found in this function, where J⃗ is the spin polarization of the parent nuclei
and ⃗σ , p⃗e , and Ee are the spin polarization, momentum,
and electron energy, respectively. A-correlation is theanisotrpy of β-ray emission. In the case of 8 Li, A = − 13 .
Both A- and R-correlation terms are proportional tothe parent nuclei’s polarization. Therefore, we adopt Rasymmetry (Mott Scattering angle asymmetry) divided
by A-asymmetry (β ray emission rate asymmetry) as ascale of coeﬃcient R.
In our previous studies, we recognized a systematic
eﬀect that causes a large fake R-asymmetry. It is estimated that the source of this systematic eﬀect is accidental coincidence, and it shows an obvious dependence
on the width of the coincidence window and beam intensity.2) We assume an evaluation model function ofFig. 1. Schematic of CDC.
∗1
∗2
∗3
∗4
∗5

Fig. 2. Beam-intensity and coincidence-window dependenceof Mott scattering asymmetry. The red line indicatesfitting with Eq. (2).

fake asymmetry Asym(x). The variable x is presented
as a product of the beam intensity and the width of thecoincidence window in arbitrary units.
Asym(x) =(2)

The parameter a represents fake asymmetry caused by
accidental coincidence, b/x represents the ratio of thenumber of real Mott scattering events to accidental coincidence events, and c is the asymmetry of real Mott
scattering events. The limit of Asym(x) as x approaches
0 is c. This means that the y-intercept of this functionis the coeﬃcient R, which we want to know. Figure 2
shows 1183 measured asymmetry data points acquired in2017. The measurement time was 400 s per plotted data
point. The beam intensity was about 105−7 pps, and thecoincidence window varies from 100 ns to 3000 ns. Thisshows that our model is suitable for evaluating the scaleof fake asymmetry as a function of the product of beam
intensity and the width of the coincidence window.
The accidental coincidence model we use is assumed
with consideration of the double coincidence of β rays,
but there can be triple or more coincidence events. Multiple coincidence could cause other eﬀects of fake asymmetry. We need to evaluate this factor to draw a conclusion from our data.
References

Department of Physics, Nagoya University
RIKEN Nishina Center
TRIUMF
Department of Physics, Rikkyo University
Cyclotron and Radioisotope Center, Tohoku Universityac+.
1 + xb
1 + xb1) J. D. Jackson, S. B. Treiman, H. W. Wyld Jr., Phys. Rev.
106, 517 (1957).
2) J. Murata et al., Hyperfine Interact. 237, 125 (2016).

- 66 -

2. Nuclear Physics (Theory)Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 53

Non-relativistic expansion of Dirac equation with spherical vector andscalar potentials†
Y. X. Guo∗1,∗2,∗3 and H. Z. Liang∗2,∗1
Since the 1970s, the density function theory (DFT)in both the non-relativistic and relativistic frameworks has succeeded in microscopically describing the
ground-state and excited-state properties of thousandsof nuclei in a self-consistent manner. However, theconnection between these two frameworks remains unclear. The non-relativistic expansion of the Dirac equation is considered to be a potential bridge connecting
these two frameworks.1,2)
In 2012, Guo3) ﬁrst applied the similarity renormalization method (SRG)4,5) to perform the nonrelativistic expansion of the Dirac equation. By using
SRG, the Dirac Hamiltonian can be transformed intoa diagonal form after inﬁnite steps of unitary transformations, i.e., the eigenequations for the upper andlower components of the Dirac spinors can be decoupled. Furthermore, the Hamiltonian H thus obtained
was expanded in powers of 1/M (with M being thebare mass of the nucleon).
The results up to the 1/M 3 order were calculated.3)
However, the diﬀerences between the corresponding
results and the exact ones were still approximately
1 MeV. Therefore, it is necessary to include higherorder corrections. In this work, the results up to the
1/M 4 order are calculated, and the diﬀerences between
the calculated and exact values are less than 0.2 MeV
for all states.
From a simple observation, some geometric progressions are determined in the results of the conventional SRG method. This observation is reminiscentof the idea of resummation. In the reconstituted SRG
method, replacing M with the Dirac mass M ∗ = M +S
(with S being the scalar potential) not only yields the
non-relativistic expansion up to a certain order, butalso sums up the terms that belong to their families
up to inﬁnite order. Consequently, the convergence ofthe reconstituted SRG is much faster than that of theconventional SRG. The spectrum of the HamiltonianH̃ thus obtained is shown in Fig. 1.
The Foldy-Wouthuysen (FW) transformation6–9) is
another non-relativistic expansion method that has
been widely used. Both the FW transformation and
SRG method provide a systematic way to perform thenon-relativistic expansion of the Dirac equation up to
an arbitrary order. Thus, we also apply the FW transformation to a general case of the covariant DFT. In
†
∗1
∗2
∗3

-10
3p3/2
2f 5/2E (MeV)-20-30

2f 7/2

-40

1h9/2

2p3/2

2d5/2

1f 5/2

-50
I

II

III

Exact

1g7/2

I

II

III

Exact

Fig. 1. Energy spectrum of H̃ for the four pseudospin partners calculated using the reconstituted SRG method.
The first, second, and third columns show the singleparticle energies up to the first, second, and third orders, respectively. The last column, labeled “Exact,”shows the eigenenergies of the Dirac equation.

this work, the results with the FW transformation havealso been obtained up to the 1/M 4 order and comparedwith the corresponding results obtained using conventional SRG method. It seems that the FW transformation and the conventional SRG method produce thesame results up to the second order, but they show differences from the third order. By introducing a blockdiagonal transformation Ξ, we determined that the results obtained using the conventional SRG method areequal to those obtained using the FW transformation
with an additional unitary transformation Ξ. Consequently, the spectrum of the single-particle energy obtained using the FW transformation is identical to thatobtained using the SRG method.
With the applications of the SRG method and FW
transformation, the bridge connecting the DFT in therelativistic and non-relativistic frameworks is now conceivable.
References

1) P. G. Reinhard, Rep. Prog. Phys. 52, 439–514 (1989).
2) M. Bender, P. H. Heenen, P. G. Reinhard, Rev. Mod.
Phys. 75, 121–180 (2003).
3) J. Y. Guo, Phys. Rev. C 85, 021302 (2012).
4) F. Wegner, Ann. Phys. Berlin 506, 77–91 (1994).
5) A. B. Bylev, H. J. Pirner, Phys. Lett. B 428, 329–333(1998).
6) M. H. L. Pryce, Proc. Royal Soc. A 195, 62–81 (1948).
7) L. L. Foldy, S. A. Wouthuysen, Phys. Rev. 78, 29–36(1950).
8) S. Tani, Prog. Theor. Phys. 16, 267–285 (1951).
9) L. L. Foldy, Phys. Rev. 87, 688–693 (1952).

Condensed from the articles in Phys. Rev. C 99, 054324(2019) and Chin. Phys. C 43, 114105 (2019)
Department of Physics, The University of Tokyo
RIKEN Nishina Center
Department of Modern Physics, University of Science andTechnology of China- 67 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 53

Renormalizing random-phase approximation by using exact pairing†L. Tan Phuc,∗1 N. Quang Hung,∗1 and N. Dinh Dang∗2
1.2

The random-phase approximation (RPA) is a popular theoretical method to study the low-lying excitations and high-lying giant resonances in nuclei. The
excited states of RPA are built on the particle-hole(ph) components, which are represented by the ph pairs†. Because of the unknown
operators: Bph and Bphof the RPA ground state |RP A⟩, the quasi-boson approximation (QBA), which assumes a ph pair as a boson and |RP A⟩ ∼ |HF ⟩, is used to derive the RPA
expectation value, namely ⟨RP A|[Bph , Bp†′ h′ ]|RP A⟩ ∼

†

∗1
∗2

Condensed from the article in Phys. Rev. C 99, 064322 (2019)
Duy Tan University
RIKEN Nishina Center- 68 -B IV (E1)(e 2fm2)

RPA
HFEPRPAHFEPRPA-SC

0.8
0.6
0.4
0.2
0
5

10

15
E (MeV)201015E (MeV)201015E (MeV)

20

6
60

b) Ni
B IV (E1)(e 2fm2)

5
4
3
2
1
0
5
8

c)

7

90

Zr

6
B IV (E1)(e 2fm2)⟨HF |[Bph , Bp†′ h′ ]|HF ⟩ = δpp′ δhh′ .1) Using QBA within
RPA leads to a basic drawback that is the violation ofPauli principle because the nucleons are fermions insteadof boson as the assumption of QBA.
To overcome this problem, the ground-state correlations (GSC) factor Dph are taken into account to renormalize the residual interaction of
RPA (RRPA). The RPA expectation value becomes⟨RP A|[Bph , Bp†′ h′ ]|RP A⟩ ≃ Dph ≡ fh − fp , where fp
and fh are p and h occupation numbers.2) Although the
RRPA restored the Pauli principle, the energy-weighted
sum rule (EWSR) was violated.3) Therefore, anothertechnique was developed to ﬁx this drawback, namely
the pp and hh correlations were added in the phRRPA
matrix to fulﬁll the EWSR.3) However, this way doubled the matrix size of RPA equations and lead to timeconsuming. On the other hand, the RRPA does notinclude superﬂuid pairing. Therefore, we propose amethod to overcome all these shortcomings. In particular, by using the Hartree-Fock mean ﬁeld plus exact
pairing solution (HFEP),4) we can supply a good setof initial inputs for RPA. The GSC factor Dph , which
is used to renormalize the residual interactions, is calculated directly from exact pairing (EP). These are expected to preserve both Pauli principle and EWSR without adding any pp and hh correlations that make timeconsuming.
The proposed approach is applied for the dipole
case in several light-, medium-, and heavy-massThe
nuclei, namely 22, 24, 28 O, 60 Ni, and 90 Zr.
calculations are performed within the conventional
RPA, HFEP+RPA (HFEPRPA) and self-consistent
HFEPRPA (SC-HFEPRPA). The E1 EWSR will becompared with the model independent sum rule suchas the Thomas-Reich-Kuhn (TRK) sum rule. Our approach shows that the drawback of the phRRPA is removed, namely the EWSR are fulﬁlled without adding
any pp and hh conﬁgurations, hence the extensionof RPA matrices and time-consuming calculations are
avoided. As compared to the RPA results, the eﬀects

22

a) O
1

5
4
3
2
1
0
5

Fig. 1. The Isovector dipole transition probabilities of 22 O(a), 60 Ni (b) and 90 Zr (c) obtained within diﬀerent approaches. The sticks and lines represent to the probabilities B(E1, 0 → 1− ) and strength functions S(E).

of GSC and EP in the renormalization are signiﬁcant inlight nuclei and small in medium and heavy nuclei (seethe shift of S(E) in Fig. 1(a)–(c)). The antipairing eﬀect
is observed for the ﬁrst time within the SC-HFEPRPA,
which reduces the pairing energy from more than 10%
up to around 30% in the neutron-rich 22 O nucleus. Thisshows the contribution from the mutual eﬀect of theshort-range pairing and long-range ph residual interaction to the mean ﬁeld. The PDR is also found to beenhanced in neutron-rich nuclei because of the pairingeﬀect.
References

1) P. Ring, P. Schuck, The Nuclear Many-Problem (Springer,
2004).
2) F. Catara, N. D. Dang, M. Sambataro, Nucl. Phys. A
579, 1 (1994).
3) N. Q. Hung, N. D. Dang, T. V. N. Hao, L. T. Phuc, Phys.
Rev. C 94, 064312 (2016).
4) L. T. Phuc, N. Q. Hung, N. D. Dang, Phys. Rev. C 97,
024331 (2018).

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 53

Quenching factor of Gamow-Teller and spin dipole resonances†
L. -G. Cao,∗1 S. -S. Zhang,∗2 and H. Sagawa∗3,∗4

Ex =0

Ex =0

where Ex (max) is taken to be 30 MeV in the GT case.
The quenching factor qf = 0.64 corresponds to a renormalization factor of qRF = 0.80 for the GT transition
operator to retain the empirical sum rule value.
The calculated SD strength for 48 Ca is shown in Fig. 1.
†
∗1
∗2
∗3
∗4

Condensed from the article in Phys. Rev. C 100, 054324(2019)
School of Mathematics and Physics, North China ElectricPower University
School of Physics and Nuclear Energy Engineering, Beihang
University
RIKEN Nishina Center
Center for Mathematics and Physics, University of Aizu

- 69 -

6-1

SGT- (MeV )

5
4
48

Exp.
SAMi
SAMi(qf=0.64)
SAMi-T
SAMi-T(qf=0.64)

Ca

3
2
1
0
0

-1

15

2

20

10

SSD- (fm MeV )Spin-isospin excitations provide a unique opportunity
to study the spin correlations in nuclei. The GamowTeller (GT) transition is the simplest with both spin
and isospin transfers by one unit. The next simplest is
spin-dipole (SD) excitations, which involve the orbital
angular momentum transfer by one unit together withspin and isospin transfer. The quenching of the total
GT strength from the model-independent sum rule has
prompted theoretical studies of possible mechanisms,
ranging from conventional conﬁguration mixing to an
admixture of ∆-hole states. Experimental investigationsof the (p, n) and (n, p) reactions using the multipole decomposition (MD) technique have identiﬁed not only the
GT strength but also a considerable amount of broadly
distributed L = 1 SD strength at excitation energies
beyond the GT peak.
We study GT and SD states in four doubly magic
nuclei 48 Ca, 90 Zr, 132 Sn, and 208 Pb by using the selfconsistent Hartree-Fock+random-phase approximation(RPA) model with/without tensor interactions. We
adopt the modern energy density functions (EDFs)
SAMi and SAMi-T for the theoretical study. The latterhas tensor terms determined from Bruckner HF calculations with the AV18 interaction.
The GT strength is shown in Fig. 1 for the t− channel of 48 Ca. The main experimental GT resonance wasfound experimentally at Ex ∼10 MeV, in addition to asmall peak at Ex = 3 MeV in 48 Ca. The results calculated with SAMi reproduce well the main peak, but thelow-energy strength is predicted 1 MeV lower than theexperimental one. SAMi-T gives essentially the same
results for the main peak, but reproduces better the excitation energy for the small lower energy peak. The
integrated GT strength from Ex = 0 → 25 MeV is 15.3,
which is 64% of the GT sum rule. The calculated results exhaust almost 100% of the sum rule up to Ex =20 MeV. The quenching factor for the transition strengthis deﬁned as/ Ex (max)Ex (max)∑∑qf =B(GT : Ex )exp
B(GT )cal ,

5

10
15
E (MeV)

20

25

Exp.
SAMi
SAMi(qf=0.66)
SAMi-T
SAMi-T(qf=0.73)
48
Ca Total

5
0
0

10

20
E (MeV)30

40

Fig. 1. RPA strength functions of 48 Ca for the t− channel ofGT and SD resonances. The solid circles are the experimental data taken from Ref. 1). The short-dotted (shortdashed) and solid (dashed-dotted) lines are the theoretical results without and with a quenching factor given by
the SAMi (SAMi-T) EDF, respectively.

The tensor interactions have substantial eﬀects on the
SD response, and the eﬀect is diﬀerent for each multipole. As a net eﬀect, the main peak at Ex ∼23 MeV isshifted to a lower energy by 1 MeV by the tensor eﬀect,
which provides a better description of the experimental
strength distributions of SD for 48 Ca.
The quenching eﬀect is modest for the SD strength.
In 48 Ca, the qf value is 0.66 (0.73) for the SD with theSAMi (SAMi-T) EDF. In 90 Zr, the GT needs qf = 0.7,
while the SD shows qf = 0.8. The feature of quenchingis the same for 208 Pb; qf = 0.65 for the GT and qf =0.78(0.80) for the SD with the SAMi (SAMi-T) EDF.
In conclusion, the quenching eﬀect is modest for the
SD strength with the quenching factor qf ∼ 0.8 compared with that for GT, for which qf ∼ (0.55 − 0.69),
which is consistent with the quenching value obtained
from the GT beta decay processes in nuclei with A < 50.
This diﬀerence in the eﬀective quenching factors between
GT and SD should be implemented in future theoreticalstudies of double beta decay probabilities.
Reference

1) K. Yako et al., Phys. Rev. Lett. 103, 012503 (2009) andprivate communications.

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 53

Pairing in excited nuclei: a review†N. Quang Hung,∗1 N. Dinh Dang,∗2 and L. G. Moretto∗3
1012

The present review summarizes the recent progressin the study of pairing properties in excited nuclei andtheir analogy to those appeared in other ﬁnite systems including superconductors, metallic nano sizedclusters/grains, and solid-state materials such as ferromagnets. The review consists of four parts.
The ﬁrst part discusses the treatment of pairing
within a uniform model based on the BCS Hamiltonian within the grand canonical ensemble.
The second part focuses on the grandcanonical treatment of pairing within the Hartree-Fock-Bogoliubov
theory and ﬁnite-temperature pairing reentrance phenomenon in superconducting ultrasmall metallic grains
as well as in even-even and odd nuclei.
The third part presents the results obtained fromthe treatment of nuclear pairing within the canonicaland microcanonical ensembles, from which the eﬀectcaused by the ﬁnite size of the systems is highlighted.
Diﬀerent approaches to canonical and microcanonical ensembles including particle-number projection,
particle-number projection plus static path approximation, solutions of BCS with Lipkin-Nogami particlenumber projection incorporating the self-consistentquasiparticle random-phase approximation embedded
into the canonical and microcanonical ensembles, shellmodel Monte Carlo method at ﬁnite temperature, andexact solutions of the pairing problems, which are embedded into the canonical and microcanonial ensembles, are introduced.
In the fourth part, the ﬁrst experimental evidenceof the pairing reentrance phenomenon in a warm rotating 104 Pd nucleus, which was observed via the local enhancement of nuclear level density at low temperature and high angular momentum extracted fromthe reaction 12 C + 93 Nb at the incident energy of 40–
50 MeV, is analyzed and discussed within the framework of the ﬁnite-temperature BCS (FTBCS), which
includes the quasiparticle-number ﬂuctuations (FTBCS1) at angular momentum J (Fig. 1). The similar behavior of pairing reentrance observed in thecondensed-matter counterpart such as metallic compound of Eu0.75 Sn0.25 Mo6 S7.2 Se0.8 and heavy-fermion
cubic system of CePb3 , quasi-2D organic conductor κ(BETS)2 FeCl4 , and ferromagnetic superconductor of
URhGe under the strong magnetic ﬁeld is also summarized.
It has been found that, by applying the BCS theory
†
∗1
∗2
∗3

ρ (MeV -1 )

1010
8

10

Exp
FTBCS
FTBCS1

10 6
104
_

_

102

(b) J = 10 h(a) J = 0 h

100

ρ (MeV -1 )

1010
108
10 6
104
_

10

_

(c) J = 20 h102(d)J = 30 h

0

0

5

10

15

20

E* (MeV)

25

0

5

10

15

20

25

E* (MeV)Fig. 1. Level densities for 104 Pd as function of excitationenergy E ∗ at the quadrupole deformation parameterβ2 = 0.276 and diﬀerent values of total angular momentum J. The dotted and dashed lines stand for the
FTBCS and FTBCS1 results, respectively. The solidlines are the experimentally extracted level densities.

at ﬁnite temperature and angular momentum to theuniform nuclear model, for which the analytic solutions of the BCS equation can be obtained, one is able
to study the appearance of the ﬁrst-order and secondorder phase transitions in ﬁnite nuclear systems wheneither the total angular momentum or the number ofquasiparticles or the total energy of the system is ﬁxed.
However, it has also been pointed out that these shapephase transitions are simply an artifact caused by theapplication of the BCS theory to ﬁnite nuclei, neglecting all the thermal ﬂuctuations. In fact, strong thermal
ﬂuctuations in ﬁnite systems smooth out all the phasetransitions, leading to diﬀerent behaviors of nuclear
thermodynamic quantities. For example, the ﬂuctuations of the quasiparticle number are one of the microscopic origins caused the nonvanishing nuclear pairing
gaps at ﬁnite temperature, resulting in the smoothingof the superﬂuid-normal (second-order) phase transition. This ﬁnding is important in the sense that thermal ﬂuctuations should always be considered whenever
the statistical methods are applied to ﬁnite systems.

Condensed from the article in Rep. Prog. Phys. 82, 056301(2019)
Duy Tan University
RIKEN Nishina Center
University of California at Berkeley and Lawrence Berkeley
National Laboratory- 70 -

30

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 53

Canonical base in self-consistent constrained HFB in odd-A nuclei†
K. Sugawara-Tanabe∗1,∗2 and K. Tanabe∗3
We developed a program for solving the selfconsistent Hartree-Fock-Bogoliubov (CHFB) equation
under four constraints, one each on the total angularmomentum I, proton number Z+ in the + parity proton shell (p+ ), proton number Z− in the − parity
proton shell (p− ), and neutron number N , so thatit reproduces the 11/2− band in 135 Pr. We choose
the signature-invariant base Ck and Ck̂ , where k̂ isthe time-reversed level of k, and adopt a Hamiltonian
with spherical single-particle energies plus the residual quadrupole-quadrupole, monopole-pairing, andquadrupole-pairing interactions. In this signatureinvariant base, the generalized density matrix K(=
K 2 ) is expressed in terms of ρ1kl = ⟨Cl† Ck ⟩, ρ2k̂l̂ =Ρ1 C � Ρ2 C in canonical base

1.4

ii

∗1
∗2
∗3

     

 




0.8




odd nucleon in p�

0.6


�

p
 p�
 p� 14
� p� 17

0.4

0.0
15 10

5

0



  








  








5

10

15

  
20

Ξ1 � Ξ2 2 MeVii

�c� in canonical base MeV

1.4

B Gap in the canonical base

1.2

 p�
 p�
 p� 14
� p� 17

1.0
0.8
0.6





   
  






 
   







  


0.4
  

0.2




 
 


  


 


 



0.0
15 10

5

0

5

10

15

20

Ξ1 � Ξ2 2 MeVîîFig. 1. (A) ρ1c = ρ2c in the canonical base as a functionof (ξ 1 + ξ 2 )/2 at the I = 31/2− state. (B) ∆c in the
canonical base as a function of (ξ 1 + ξ 2 )/2 at the I =31/2− state. In both figures, filled circles represent the
proton levels in the p+ shell with Z+ = 14, and filledsquares represent the proton levels in the p− shell with
Z− = 17. Open circles and open squares indicate the
CHFB solution under Z = 14+17 = 31. The red filledsquare level with Z− = 17 and the red open-squarelevel with Z = 31 are mainly from h11/2 . See the text
for further details.

where ξ 1 = (F 1 )−1 (h1 − ωjx )F 1 , ξ 2 = (F 2 )−1 (h2 +ωjx )F 2 , and ∆c = (F 2 )−1 ∆F 1 . Here h1 , h2 , and ∆are deﬁned in Eq. (1) in Ref. 1). In Fig. 1, we compare the CHFB solution under three constraints for
I = 31/2, Z = Z+ + Z− , and N (open squares andopen circles) with the CHFB solution under four constraints (ﬁlled squares and ﬁlled circles). Here, thecircles correspond to the p+ shell, and squares correspond to the p− shells. The quantities represented by
the red ﬁlled square under the constraint Z− = 17 andthe red open square under Z = 31 are composed of thecontribution mainly from the h11/2 level with jz = 5/2.
The number Z = 31 corresponds to the proton number
outside core 28 for 135 Pr. As shown in (A) of Fig. 1,
ρ1c = ρ2c ∼ 1/2, i.e., 1/2 × 2 = 1 in the p− shell, we
conﬁrm that the solution certainly describes the negative parity band in the odd-Z nucleus (11/2− band in
†

1.0

0.2

⟨Cl̂† Ck̂ ⟩ and κk̂l = ⟨Cl Ck̂ ⟩, where the state | ⟩ is thequasiparticle vacuum. The CHFB equation is given as
Eq. (1) in Ref. 1). After rendering the dangerous term
zero through the iteration procedure, we can transform the elements in K to the canonical forms, i.e.,111c2 −1 222c(F 1 )−1
km ρmn Fnk ≡ ρkk and (F )k̂m̂ ρm̂n̂ Fn̂k̂ ≡ ρk̂k̂ ; thus
(F 2 )−1
κ F 1 ≡ κck̂k . In other words, K is transk̂m̂ m̂n nk
formed to Kc , and the relation Kc2 = Kc follows. Subsequently, we obtain ρ1c = ρ2c . If we apply the sametransformation to the CHFB matrix (see Eq. (1) in
Ref. 1)), we obtain


1
2
(ξ
+ξ
)/2
1
ii
2c
îî
 , (1)1−√ρ1cii = ρîî =2c2(∆ ) +((ξ 1 +ξ 2 )/2)2îi

A Density in the canonical base

1.2

135

Pr). In (B) of Fig. 1, we compare ∆ciî between the
CHFB solution under three constraints and the CHFB
solution under four constraints The blocking eﬀect isclearly indicated by the red ﬁlled or open squares because these gap values are much smaller than those forthe other levels.

Condensed from the talk at the autumn meeting of Japan
Physical Society, Yamagata University, Sept. 18th (2019)
RIKEN Nishina Center
Department of Information Design, Otsuma Women’s University
Department of Physics, Saitama University

Reference
1) K. Sugawara-Tanabe, K. Tanabe, RIKEN Accel. Prog.
Rep. 52, 1148 (2019).

- 71 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 53

S-shaped heat capacity in an odd-odd deformed nucleus†

†

∗1
∗2
∗3
∗4
∗5
∗6
∗7

100

0

80

-40

Entropy

-20
212

At
211
Po
200
Tl
184
Re

-60
-80
0.4

0.8

1.2

1.6

Temperature (MeV)

2.0

100

- 72 -

400

0.0

Condensed from the article in Phys. Lett. B 789, 634 (2019)
Bankura University
Institute of Fundamental and Applied Sciences, Duy Tan University
Variable Energy Cyclotron Centre
Dept. of Phys., Barasat Govt. College
RIKEN Nishina Center
Department of Natural Science and Technology, University of
Khanh Hoa
Dept. of Phys., Raniganj Girls’ College

60

20

-100

0.0

0.4

0.8

1.2

1.6

2.0

0.0

0.4

0.8

1.2

1.6

2.0

Temperature (MeV)

120
100

80

Heat Capacity

Average Energy (MeV)

A long-standing problem in nuclear physics is theexperimental observation of the pairing phase transition in atomic nuclei. Thermodynamic properties suchas superﬂuidity and pairing phase transition are wellestablished facts in inﬁnite nuclear matter.1) However,these properties digress from inﬁnite nuclear matter toﬁnite nuclei owing to statistical ﬂuctuations in the order parameter. Therefore, the gradual transition fromstrongly correlated paired states to unpaired ones inatomic nuclei may not be as evident as in inﬁnite matter.1) This induces a high degree of interest in the studyof nuclear thermodynamics, especially in the energy domain of neutron binding.
The study of thermodynamics of ﬁnite nuclei involves
the reliable extraction of experimental nuclear level density (NLD). The experimental determination of NLDs
has been diﬃcult in the past owing to the absence ofsuitable experimental techniques. Recently, the thermal
properties of diﬀerent nuclei were measured by the Oslogroup using a new technique, called the Oslo method,
and the S-shaped canonical heat capacity was extracted,
signalizing the pairing phase transition around the critical temperature Tc = 0.5–1.0 MeV.2,3) However, thismethod is limited to a low excitation energy E ∗ (below
the particle threshold) and angular momentum J (onlya few multiples of ℏ). This limitation in E ∗ and J has
recently been overcome by measuring the NLD from theevaporated particle spectra in compound nuclear reactions.3) In addition, thus far, most of the thermal properties have been studied in nuclei where the shell eﬀect(δS) is very small (less than ∼1 MeV). The mass region
exhibiting a large shell eﬀect (δS ∼ 10 MeV) has rarely
been studied; and thus, it is very important to investigate how the thermodynamic properties behave becauseof the large eﬀect of nuclear shells. In this work, theNLDs and, consequently, the nuclear thermodynamic
quantities (TQs) for four diﬀerent nuclei, 184 Re, 200 Tl,
211
Po, and 212 At, are estimated to understand the shelland deformation eﬀects on the TQs.
Figure 1 shows the free energy F , average energy E,
entropy S, and heat capacity C as functions of T . F
and E behave smoothly with varying T for all the nuclei. However, S and C show diﬀerent variations with T .
The diﬀerence in entropy appears primarily because ofFree Energy (MeV)

B. Dey,∗1 N. Quang Hung,∗2 D. Pandit,∗3 S. Bhattacharya,∗4 N. Dinh Dang,∗5 L. T. Quynh Huong,∗6
D. Mondal,∗3 S. Mukhopadhyay,∗3 S. Pal,∗3 A. De,∗7 and S. R. Banerjee∗7

60
40
20

80
60
40
20

0

0
0.0

0.4

0.8

1.2

1.6

Temperature (MeV)

2.0

Temperature (MeV)

Fig. 1. TQs as functions of temperature obtained using the
EP+IPM level densities for J = 12 ℏ.

the diﬀerent shell structures of the nuclei at low T since
they show a smooth variation at higher T (above T =1.6 MeV), where the shell structures are predicted to bemelted. Most noteworthy is the nature of the heat capacity of 184 Re, which is completely diﬀerent from thoseof the other three nuclei. There is a pronounced bump
(S-shape) in the heat capacity of 184 Re at T ∼ 0.8 MeV,
which is close to the critical temperature Tc , where thepairing gap collapses, as predicted by the conventional
BCS theory. This S-shape in the heat capacity is interpreted as a ﬁngerprint for a pairing transition in nuclei.
The heat capacities of 211 Po, 212 At, and 200 Tl do notshow the pronounced S-shape structure, as expected for
odd-odd and odd-even nuclei. In order to understandthe S-shaped heat capacity in such odd-odd deformed
nuclei, the exact neutron and proton pairing gaps havebeen calculated as functions of T , as discussed in detailin Ref. 4). It has been shown that S-shape of the heat
capacity observed in the odd-odd deformed 184 Re nucleus at J = 12 ℏ is only due to the change in pairing
gaps caused by the change in deformation.
The authors are very grateful to Dr. Pratap Roy,
VECC, Kolkata for providing experimental neutron energy spectra.
References

1) A. Belic et al., Nucl. Phys. A 731, 381 (2004).
2) E. Melby et al., Phys. Rev. Lett. 83, 3150 (1999).
3) B. Dey et al., Phys. Rev. C 96, 054326 (2017) and references therein.
4) B. Dey et al., Phys. Lett. B 789, 634 (2019).

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 53

Evidence for three-particle correlations in nuclear matter†
W. Bentz∗1 and I. C. Cloët∗2
The properties of inﬁnite nuclear matter havebeen the subject of intensive investigations for many
decades, mainly because of the wide range of applications, including the properties of heavy nuclei, supernova explosions, and neutron stars. In particular, studies on three-particle correlations have a long
history, beginning with the pioneering work of Bethe
in 1965.1) In this paper we focus our attention on
the skewness of nuclear matter and its implications
for three-particle
correlations.
Skewness is deﬁned as
J = 27ρ3 d3 EA /dρ3 at ρ = ρ0 , where EA is the energy per nucleon in isospin symmetric nuclear matter,and ρ0 is the saturation density. Recently, empiricalvalues of J have been extracted in Ref. 2) from heavy
ion collisions and neutron star observations, and thefollowing range was deduced:−0.50 GeV < J < −0.01 GeV .

=



dΩ2
4π

M
(H0 − H1 ) > 1.24
M∗

(1)

(5)

t
t



M − M∗
4 pF dM ∗1−× − +3
+
(H
−
H
)
,
0
1
3
M
3 M ∗ dpF
(2)

t

...
t

t

Fig. 1. The ﬁrst two terms in the Faddeev series of thethree-particle amplitudes. Genuine three-particle correlations start with the second diagram. The circles
represent two-body t-matrices.

where K is the incompressibility, pF the Fermi momentum, M ∗ ≡ M ∗ (k = pF ) the Landau eﬀective mass∗dM ∗ (k)at the Fermi surface, dM|k=pF the slope
dpF =dkof M ∗ (k) at the Fermi surface, and the dimensionless
three-particle interaction parameters H� (� = 0, 1) aredeﬁned by
2pF M ∗
h� ,
ρ
(3)
H� =
0
π2

References
1) H. A. Bethe, Phys. Rev. B 138, 804 (1965).
2) B. -A. Li, B. -J. Cai, L. -W. Chen, J. Xu, Prog. Part.
Nucl. Phys. 99, 29 (2018).
3) J. Negele, H. Orland, Quantum Many-particle systems(Springer, 1980).
4) C. Mahaux, P. F. Bortignon, R. A. Broglia, C. H. Dasso,
Phys. Rep. 120, 1 (1985).
5) J. P. Blaizot, B. L. Friman, Nucl. Phys. A 372, 69(1981).
6) E. N. E. van Dalen, C. Fuchs, A. Faessler, Phys. Rev.
C 72, 065803 (2005).
7) Z. Zhang, L. -W. Chen, Phys. Rev. C 94, 064326 (2016).
8) J. W. Holt, N. Kaiser, T. R. Whitehead, Phys. Rev. C
97, 054325 (2018).

where h� = h� (k1 = k2 = k3 = pF ) is given by the
angular average
1h� (k1 , k2 , k3 )2� + 1∗2(4)

The three-particle amplitudes H� satisfy a Faddeev
equation in the medium, with a 1-particle reducible
driving term (ﬁrst diagram in Fig. 1), and genuine
three-particle correlations, which start with the second diagram in Fig. 1. The driving term can be easily estimated by using eﬀective contact interactions of
the Landau-Migdal type, and give a contribution between 0.75 and 1.23 to Eq. (5). (Here we used theLandau-Migdal parameters obtained from Skyrme interactions7) ) and chiral eﬀective ﬁeld theory.8) ) This
gives us an important hint that two-particle correlations alone cannot satisfy the inequality Eq. (5), andthree-particle correlations processes are needed to explain the skewness of nuclear matter.

9p2F
J = −9K + ∗2
M∗1

dΩ3  ˆ ˆ �
k1 · k2 h(k1 , k2 , k3 ) .
4π

By using empirically and theoretically obtained ranges
for the incompressibility,2) the eﬀective mass M ∗ ,4)and its slope at the Fermi surface,5,6) we can deduce
the following inequality from (1) and (2):

By using the theoretical framework of the LandauMigdal theory, we will show that those empirical values
provide us with information on three-particle correlations in nuclear matter.
Extending Landau’s basic formula3) for the variationof the energy density of nuclear matter to include thethird order term, which involves the totally symmetricspin-isospin averaged three-particle forward scattering
amplitude h(k1 , k2 , k3 ), we are able to derive the following exact expression for J:†



Condensed from an article by W. Bentz and I. C. Cloët,Phys. Rev. C 100, 014303 (2019).
Department of Physics, Tokai University
Physics Division, Argonne National Laboratory- 73 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 53

Double charge-exchange phonon states†
X. Roca-Maza,∗1,∗2 H. Sagawa,∗3,∗4 and G. Colò∗1,∗2
The possibility of inducing double charge-exchange
excitations by heavy-ion beams at intermediate energies has recently fostered interest in new collective excitations such as double isobaric analog states (DIAS)
and double Gamow-Teller giant resonances (DGT). We
present some formulas to evaluate diﬀerent combinationsof the average excitation energies of DIAS and DGTR
by using commutator relations.
The expectation value for the energy of the DIAS
(DGT) is deﬁned as
EDIAS(DGT) ≡ ⟨DIAS(DGT)|H|DIAS(DGT)⟩− ⟨0|H|0⟩.

(1)

Here |0⟩ represents the ground state, and|DIAS(DGT)⟩ ≡O− |IAS(GT)⟩⟨IAS(GT)|O+ O− |IAS(GT)⟩1/2(2)

is the deﬁnition of the DIAS (DGT) state in terms of
the IAS (GT), which can be written as
O− |0⟩|IAS(GT)⟩ ≡.
⟨0|O+ O− |0⟩1/2(3)∑AThe operators O± = T± ≡i t± (i) are the isospin
raising and lowering operators∑
for IAS and DIAS. ForA
GT and DGT, O± = G± ≡i σz (i)t± (i). Startingfrom Eq. (1), one may write the excitation energy of the
DIAS (DGT) as
EDIAS(DGT) =22, [H, O−]]|0⟩⟨0|[O+,
2
2⟨0|O+ O− |0⟩(4)

assuming that the ground state has good isospin, thatis, there is no isospin mixing and T+ |0⟩ = 0. Within thesame approximation, EIAS(GT) reads
EIAS(GT) = ⟨IAS(GT)|H|IAS(GT)⟩ − ⟨0|H|0⟩=⟨0|[O+ , [H, O− ]]|0⟩.
⟨0|O+ O− |0⟩(5)

EDIAS(DGT) = 2EIAS(GT)⟨0|[O+ , [O+ , [[H, O− ], O− ]]]|0⟩.
2(N − Z)(N − Z − 1)

(6)

The denominator of Eq. (4) is evaluated to be
2 2
⟨0|O+
O− |0⟩ = 2(N − Z)(N − Z − 1). The second term
†
∗1
∗2
∗3
∗4

H = H0 + V + VC + VISB ,(7)

where V is the spin- and isospin-dependent interaction,
VC is the Coulomb interaction, and VISB is an ISB effective interaction originating from the nuclear strong
force. From Eq. (6), we can derive the relation between
the DGTR and DIAS energies as,
EDGTR − EDIAS =⟨0|[G2+ , [V, G2− ]]|0⟩,2(N − Z)(N − Z − 1)(8)since [G2+ , [VC + VISB , G2− ]] = [T+2 , [VC + VISB , T−2 ]] . In
order to evaluate the energy diﬀerence between EDGTR
and EDIAS , we adopt the separable interaction1)
V =

A
∑
i

+

A

κls l(i) · s(i) +

1 κστ
2 A

A
∑
i̸=j

1 κτ ∑
τ (i) · τ (j)
2 A
i̸=j

(σ(i) · σ(j))(τ (i) · τ (j)),(9)

where κls is the one-body spin-orbit coupling strength,
while κτ and κστ are the coupling strengths of the residual two-body interactions in the isospin and spin-isospin
channels, respectively. The average energy of the GTR
minus that of the IAS is expressed as⟨0|[G+ , [V, G− ]]|0⟩
EGT − EIAS =(N − Z)
� ⟩
⟨ � A
�
�
4 κls
N −Z
�∑
�
=−
0�
.
l(i) · s(i)� 0 +2(κστ −κτ )��
3 N −ZAi

One can write the energies for DIAS and DGT as+on the right-hand side in Eq. (6) could be diﬀerent fromzero only for the isospin symmetry breaking (ISB) termsin H because they contribute to EIAS [cf. Eq. (5)]. In
other words, the IAS and DIAS energies are a special ﬁlter for the terms in the Hamiltonian that break isospin
symmetry (Coulomb and the small contributions fromthe strong force), while the isospin-conserving part of H
does not contribute.
In order to evaluate the quartic and double commutators, we take the Hamiltonian

Condensed from the article in Phys. Rev. C 101, 014320(2020)
Dipartimento di Fisica “Aldo Pontremoli,” Università degliStudi di Milano
INFN, Sezione di Milano
RIKEN Nishina Center
Department of Physics, Omsk University- 74 -The energy diﬀerence between DGTR and DIAS (8) is
expressed in a similar manner as)(
N −Z(EGT −EIAS )EDGTR −EDIAS − 1+
N −Z −1⟩⟨ ∑A
4 κls 0| i l(i) · s(i)|01 N −Z−6(κστ −κτ ).
=3 (N −Z)(N −Z −1)
A N −Z −1
Quantitative discussions of the above formulas are reported elsewhere.
Reference
1) A. Bohr, B. R. Mottelson, Nuclear Structure Vol.I (World
Scientific, 1975).

3. Nuclear Data

Ⅱ-3. Nuclear Data

RIKEN Accel. Prog. Rep. 53

EXFOR compilation of RIBF data in 2019
T. Tada,∗1 S. Imai,∗2 D. Ichinkhorloo,∗3 M. Kimura∗3,∗4 M. Aikawa,∗3,∗5 and N. Otuka∗5,∗6
Nuclear-reaction data support the most essential
part of nuclear technologies (e.g., nuclear power production, nuclear fuel cycles, environmental monitoring,
dosimetry, radiation safety, radioisotope production,
radiotherapy, and medical diagnostics) and sciences(e.g., nuclear physics, nuclear chemistry, geophysics,
and astrophysics). Nuclear databases play a vital rolein providing the best estimate for nuclear reactions toa wide range of data users in various scientiﬁc ﬁelds
and related areas. One of the largest global nuclear
reaction databases open to the public is the EXFOR
library (EXchange FORmat for experimental nuclear
reaction data).1) The EXFOR library is a universal
common repository for nuclear reactions establishedin 1967. The International Network of Nuclear Reaction Data Centres (NRDC) maintains the EXFOR
library under the auspices of the International Atomic
Energy Agency (IAEA).2) The scope of the EXFOR
library covers a wide range of nuclear reactions suchas neutron-, charged-particle-, and photon-induced reactions.
Our group, the Hokkaido University Nuclear Reaction Data Centre (JCPRG),3) was founded in 1973 andjoined the NRDC as the ﬁrst Asian member in 1975.
We are responsible for the compilation of chargedparticle-, and photon-induced nuclear reactions measured at facilities in Japan.4) Our contributions to the
EXFOR database account for ∼10% of the complete
database. The database compilation process involves
the scanning of peer-reviewed journals for publishedpapers within the EXFOR scope. A unique entry number is given to each selected paper to be compiled for
the EXFOR library. We extract information from thebibliography, experimental setup, measured physicalquantities, measured numerical data, and uncertainties. The information is input in a single entry of
EXFOR. During this process, we contact the corresponding authors with questions on the contents of thepapers and requests for numerical data.
JCPRG has been cooperating with the RIKEN
Nishina Center since 2010 for the compilation of dataobtained by RIBF, which aims at the enhancement of
the availability of the RIBF data. Our activities related to the RIBF experiments are as follows. We
have compiled 48 new articles produced at Japanesefacilities and modiﬁed 42 old entries. This includes 10
∗1
∗2
∗3
∗4
∗5
∗6

articles from RIKEN, 6 new articles, and 4 old entries.
The compiled data are accessible by the entry numbers
listed in Table 1. The status of those compilations isperiodically reported via Nishina Center News.
We acknowledge that collaboration with RIKEN isa great help for us to establish an eﬀective procedure
for the compilations. Most of the RIKEN data arevery quickly compiled after publication, and the end
users can access them smoothly. We also thank all theauthors of the RIKEN articles who kindly provided numerical data. This greatly helps increase the accuracy
and quality of the database.
Table 1. Entry numbers with references compiled fromRIBF data in 2019.

New
Revised
Total

E25535)
E25868)E243011)
E253914)

Entries
E25836)
E25909)E243412)

E25847)
E259210)
E249313)

10

We would like to take this opportunity to express our
gratitude to the authors of these papers for their kindcooperation with the EXFOR compilation process.
References
1) N. Otuka et al., Nucl. Data Sheets 120, 272 (2014).
2) https://www-nds.iaea.org/ .
3) Hokkaido University Nuclear Reaction Data Centre,
http://www.jcprg.org/ .
4) M. Kimura, AAPPS Bulletin 28, 24 (2018).
5) S. Momiyama et al., Phys. Rev. C 96, 034328 (2017).
6) D. Kahl et al., Phys. Rev. C 97, 015802 (2018).
7) M. L. Cortés et al., Phys. Rev. C 97, 044315 (2018).
8) O. B. Tarasov et al., Phys. Rev. Lett. 121, 022501(2018).
9) M. Yoshie, I. Kohno, Sci. Pap. Inst. Phys. Chem. Res.
69, 63 (1975).
10) T. Murata et al., Appl. Radiat. Isot. 144, 47 (2019).
11) A. K. Kurilkin et al., Phys. Rev. C 87, 051001(R)(2013).
12) L. Y. Zhang et al., Phys. Rev. C 89, 015804 (2014).
13) H. Wang et al., Phys. Lett. B 754, 104 (2016).
14) S. Kawase et al., Prog. Theor. Exp. Phys. 2017,
093D03 (2017).

Graduate School of Science, Hokkaido University
Institute for the Advancement of Higher Education,
Hokkaido University
Faculty of Science, Hokkaido University
Research Center for Nuclear Physics (RCNP), Osaka University
RIKEN Nishina Center
NDS, IAEA- 75 -

4. Hadron Physics

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 53

Unfolding the transverse momentum distribution for very forward√
neutron production in pAu collisions at sN N = 200 GeV
B. Mulilo∗1,∗2 for the PHENIX collaboration
Smearing response matrix
0.3

True Pt [GeV/c]

The PHENIX collaboration measured that when atransversely polarized proton√ with spin up collides
with unpolarized proton at s = 200 GeV, they generate neutrons predominantly to the right.1) In 2011,
theorists explained this result in terms of the interference of pion and a1 reggeon exchanges.2) But in 2015
using run 15 pAu data, we observed that when a po√
larized proton collides with a gold nucleus at sN N
= 200 GeV, they generate more neutrons to the left3)
contrary to theoretical predictions.2) This nuclear dependence of the asymmetry (AN ) has, therefore, attracted a massive interest in nuclear physics.
We are now studying AN as a function of the transverse momentum (P t). We begin with an understanding that our measurements are limited by known eﬀects
such as the detector resolution and detection eﬃciency
among others. Our technique is, therefore, to employ
a method known as unfolding to remove these known
eﬀects and recover the distribution.
We proceed by parametrizing measurement eﬀects
using the response matrix in Fig. 1 from Monte
Carlo.4) What this matrix does is to map the binnedtrue spectrum in the magenta line onto the smeared
spectrum in the green line of Fig. 2. For the smeared
and true distribution bins Ri and Tj , respectively, thesmearing matrix element Sij gives the fraction of entries from bin Tj that end up being reconstructed in
bin Ri .
The unfolding has been performed using the singularvalue decomposition method5) contained in CERN’s
ROOT toolkit. Since our smearing matrix is not perfectly diagonal, we unfolded with a parameter, alias
Kreg,5) which determines the regularization of the unfolding. The unfolded spectrum is the distribution corresponding to an optimum regularization parameter,
Kreg = 6 as depicted in Fig. 2.
We are now optimizing and extending the ideas ofthe one dimensional unfolding to two dimensional unfolding of transverse momentum (P t) in azimuthal angle (Φ). The transverse single spin asymmetry (AN )for very forward neutron production will then be calculated as a function of the unfolded P t distribution.

0.25
0.2

0.15
0.1
0.05
0
0

0.05

0.1

0.15

0.2
0.25
0.3
Smeared Pt [GeV/c]

Fig. 1. Smearing response matrix mapping the binned true
P t spectrum to the smeared P t spectrum.
Data, unfolded, true and smeared Pt distributions (Kreg = 6)

Yield

×103

200

Data Pt spectrum

180

Unfolded Pt spectrum

160

True Pt spectrum

140

Smeared Pt spectrum

120
100
80
60
40
20
0
0

0.05

0.1

0.15

0.2

0.25
0.3
Pt [GeV/c]

Fig. 2. Superposition of the experimental data, unfolded,
true and smeared P t distributions. The P t distribution
in the green line is smeared from Monte Carlo whilethat in the dark blue line is the experimental data. The
P t distribution in the magenta line is generated using
Monte Carlo event generator.4)

References∗1∗21) A. Adare et al., Phys. Rev. D 88, 032006 (2013).
2) B. Z. Kopeliovich et al., Phys. Rev. D 84, 114012 (2011).
3) A. Aidala et al., Phys. Rev. Lett. 120, 022001 (2018).
4) G. Mitsuka, Phys. Rev. C 95, 044908 (2017).
5) Nucl. Instrum. Methods Phys. Res. A 372, 469 (1996).

RIKEN Nishina Center
Department of Physics, Korea University- 77 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 53

Update of single and dihadron cross sections for light hadrons in e+ e−√annihilation at s = 10.58 GeV in Belle††∗1cross section ratio
cross section ratio

π+π- (AEMP) / π+π- (std)π+π- (MVH) / π+π- (std)

1.4
1.2

π+π+ (AEMP) / π+π+ (std)π+π+ (MVH) / π+π+ (std)0.30 < z1 < 0.35

0.35 < z1 < 0.40

1
0.8
0.6
0.4
0.2 0.20 < z1 < 0.25

0.25 < z1 < 0.30

1.4 0.40 < z < 0.45
11.2

0.45 < z1 < 0.50

0.50 < z1 < 0.55

0.55 < z1 < 0.60

0.65 < z1 < 0.70

0.70 < z1 < 0.75

0.75 < z1 < 0.80

0.85 < z1 < 0.90

0.90 < z1 < 0.95

0.95 < z1 < 1.00

1
0.8
0.6
0.4
0.2

any hemisphere

1.4 0.60 < z < 0.65
1
1.2
1
0.8
0.6
0.4
0.2

cross section ratio

The fragmentation process describes the formationof ﬁnal-state hadrons from initial high-energetic partons such as quarks and gluons. Due to the strengthof the coupling of the strong interaction, described byquantum chromodynamics, QCD, this process is obtained only experimentally and parameterized in fragmentation functions, FFs. FFs are universal and factorize for most relevant processes and FF types. They
therefore serve as an important tool in the study ofthe spin, momentum and ﬂavor structure of the nucleon or other bound states of QCD. Its universality
can be used to extract them in one process, such as
electron-positron annihilation where no hadrons exist
in the initial state, and apply it to semi-inclusive deepinelastic lepton nucleon scattering SIDIS or hadronhadron scattering.
In the Belle experiment at the KEKB accelerator,a large amount of data exists that can be analyzed to
extract various hadronic cross sections as a functionof the fractional energy the hadrons carry relative tothe initial parton energies, as well as their spin andtransverse momentum dependence.
The extraction of the ﬂavor dependence of fragmentation functions from electron-positron annihilation is
not as easy since the cross sections are a sum over allaccessible ﬂavors, at Belle energies up, down, strange
and charm quarks. To gain some sensitivity the extraction of cross sections for two hadrons in the ﬁnal state
have been published a few years ago,1,2) where the ﬂavor dependence of each of two single hadron fragmentation functions can be used together. However, theinterpretation via single hadron fragmentation functions is only possible when both hadrons appear in opposite hemispheres which in turn can only be ensured
via additional quantities. Such variables are diﬃcult
to treat theoretically, so in an update two diﬀerent
fractional-energy deﬁnitions were used and comparedto the conventional one.
Both deﬁnitions contain scalar products between thetwo hadron’s four-momenta and therefore only havesizable fractional energies when both hadrons are far
separated without the need of an explicit hemisphereassignment. The cross section ratios for pion pairs canbe seen in Fig. 1 relative to the default deﬁnition. The
ﬁrst deﬁnition is actually the oldest one suggested for
dihadrons3) which is meant to also be able to interpret the dihadron cross sections at higher orders of thestrong coupling. The second deﬁnition is similar, but
stresses the transverse momentum in the two-hadroncross section ratio

R. Seidl∗1

1.4 0.80 < z < 0.85
1
1.2
1
0.8
0.6
0.4
0.2
0.3

0.4

0.5

0.6

0.7

0.8

0.9

z2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

z2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

z2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

z2

Fig. 1. Dipion cross section ratios as a function of fractionalenergy z2 in bins of z1 relative to the conventional fractional energy definitions. The opposite sign pairs are
displayed in blue squares and green triangles for the
AEMP and MVH definitions while the same sign pairs
are displayed by red circles and purple squares, respectively.

system.4) As can be seen, at very high fractional energies all three deﬁnitions are similar as both hadrons
need to be nearly back-to-back and no phase space fortransverse momentum remains. At low fractional momenta the cross sections using the alternative deﬁnitions are far smaller since the same-hemisphere hadronpairs would appear at much smaller fractional energies
due to the scalar product.
In addition to these updated dihadron cross sections,also single hadron cross sections were updated. The
diﬀerence to previously published single hadron crosssections for pions, kaons and protons2,5) (as well as for
dihadrons using the default fractional energy deﬁnitions) is an improved initial state radiation correction
as well as the separation of correlated and uncorrelated
systematic uncertainties.
References

1) R. Seidl et al., Phys. Rev. D 96, 032005 (2017).
2) R. Seidl et al., Phys. Rev. D 92, 092007 (2015).
3) G. Altarelli, R. K. Ellis, G. Martinelli, S. Y. Pi,
Nucl. Phys. B 160, 301 (1979). doi:10.1016/05503213(79)90062-2
4) P. J. Mulders, C. Van Hulse, Phys. Rev. D 100, 034011(2019).
5) M. Leitgab, et al., Phys. Rev. Lett. 111, 062002 (2013).

Condensed from Phys. Rev. D 101, 092004 (2020)
RIKEN Nishina Center- 78 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 53

Preparation status of the J-PARC E16 experiment in 2019
S. Yokkaichi∗1 for the J-PARC E16 Collaboration
We have proposed the experiment E161) to measure
the vector meson decays in nuclei in order to investigate
the chiral symmetry restoration in dense nuclear matter. The experiment will be performed at the J-PARC
Hadron Experimental Facility. The high-momentum
beamline, where the experiment will be conducted, isbeing constructed by KEK. Its scientiﬁc (“stage-1”) approval was granted to the experiment E16 by PAC in
March 2007. For the full (“stage-2”) approval, a technical design report was submitted to PAC in May 2014,
and reviewed for the experimental and budgetary feasibility. In the PAC meeting held in Jul. 2017, the stage-2
approval for 40 shifts (320 hours) of a commissioning
run was granted. In this run, the background measurement at the new beamline is required. The constructionof the beamline and our spectrometer is on schedule forcompletion in Feb. 2020. Only 20 shifts are allocatedin Feb.–Mar. 2020, and another 20 shifts are planned inearly 2021.
This experiment aims to systematically study thespectral modiﬁcation of vector mesons in nuclei, particularly the ϕ meson, using the e+ e− decay channel withstatistics that are two orders larger in magnitude thanthose of the precedent E3252) experiment performed at
KEK-PS. In other words, it aims to accumulate 1 × 105
to 2 × 105 events for each nuclear target (H, C, Cu, andPb) and deduce the dependence of the spectral modiﬁcation on the size of matter and meson momentum.
Our proposed spectrometer has 26 modules. Owing
to budget limitations, our ﬁrst goal of staged construction plan is to construct eight modules, as shown in
Fig. 1. With the eight-module conﬁguration, we proposed a physics run, Run-1, with 160 shifts (1280 hours),
as described in the previous APR.3)

Fig. 2. Photograph of the E16 Spectrometer, which is underconstruction.

The development of detectors and front-end modules
has been completed. Field mapping for the spectrometer magnet was performed in Jun.–Jul. 2019. We installed the detectors in the spectrometer magnet in Jul.
2019- Jan. 2020, including three layers of GEM Trackers(GTR) for tracking,4) Hadron Blind Čerenkov detectors(HBD),5) and Lead-Glass calorimeters (LG) for electron
identiﬁcation. We joined the RD516) collaboration in
CERN that aims to develop multi-pixel gas detectors including GEM. One layer of Solid-State Detector (SSD)
is introduced between GTR and the target in order tohelp the tracking under the huge background. The lastpart of development of trigger electronics,8) namely, theamp-shaper-discriminator boards to generate the trigger
signal at GTR and HBD, were completed in 2019.
We will start the commissioning run with 6 SSD, 6
GTR, 4 HBD, and 6 LG modules, out of eight modules
each, as shown in Fig. 1. The installation of detectors
has been completed, and shakedown is underway as ofJan. 2020, as shown in Fig. 2.
References

Fig. 1. Plan view of the proposed E16 Spectrometer in theeight-module configuration. The red line shows the constructed parts for the commissioning run in Feb. 2020.
The SSD located in the innermost layer is not shown.
∗1

RIKEN Nishina Center- 79 -

1) S. Yokkaichi et al., J-PARC proposal No. 16, (http://
j-parc.jp/researcher/Hadron/en/pac_0606/pdf/
p16-Yokkaichi_2.pdf); Y. Komatsu et al., JPS Conf.
Proc. 12, (2017), p. 020005; S. Ashikaga et al., JPS Conf.
Proc. 26, (2019), p. 024005.
2) R. Muto et al., Phys. Rev. Lett. 98, 042501 (2007).
3) S. Yokkaichi, RIKEN Accel. Prog. Rep. 52, 90 (2019).
4) W. Nakai et al., RIKEN Accel. Prog. Rep. 49, 195 (2015).
5) K. Kanno et al., Nucl. Instrum. Methods Phys. Res. A
819, 20 (2016).
6) http://rd51-public.web.cern.ch/RD51-Public/ .
7) https://www.psi.ch/drs/drs-chip/ .
8) T. N. Takahashi et al., J. Phys. Conf. Ser. 664, 082053(2015); M. Ichikawa et al., IEEE Trans. Nucl. Sci. 66,
2022 (2019).

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 53

Measurement of nuclear eﬀects on anti-quarks
via Drell-Yan process at FNAL-SeaQuest
K. Nakano,∗1,∗2 Y. Goto,∗2 Y. Miyachi,∗3 K. Nagai,∗4 S. Sawada,∗2,∗5 and T. -A. Shibata∗2,∗6
for the E906/SeaQuest Collaboration
The nuclear eﬀects on the partonic structure of nucleons signify that the distribution of partons in a nucleon
bound inside a heavy nucleus changes from that in afree nucleon. It was ﬁrst discovered by the EMC collaboration in 19831) and is being studied using various
measurements and theories to understand its mechanism. Most measurements made use of deep inelastic
scattering (DIS), which does not diﬀerentiate between
quarks and anti-quarks. The E772 experiment utilized
the Drell-Yan process to extract the nuclear eﬀects on
anti-quarks.2) It indicates that the eﬀects are smaller
than those observed in DIS, although the statistical precision was limited. If the diﬀerence between quarks andanti-quarks in the nuclear eﬀects is conﬁrmed, it will
be a strong constraint in understanding the mechanism
because it contradicts, for example, the conventional
nuclear model.3) A number of theoretical models were
proposed to reproduce the measured diﬀerence.4)
The E906/SeaQuest experiment at Fermilab aims tostudy the anti-quark distributions in the nucleon andnuclei. It utilizes the 120-GeV
proton beam from the√Fermilab Main Injector ( s = 15 GeV). It employs liquid hydrogen (LH2 ), liquid deuterium (LD2 ), carbon,
iron, and tungsten as targets to measure the DrellYan process in p + p, p + d, and p + A reactions. In
the Drell-Yan process, a quark in one hadron and ananti-quark in the other hadron are annihilated to produce a virtual photon, which then decays into a lepton
pair: q + q̄ → γ ∗ → l+ + l− . When it is measured
at forward rapidity (xF ≫ 0), an anti-quark nearly always originates from the target-side hadron. Therefore,
the ratios of per-nucleon cross sections of two targets,
R(A/D) ≡ (σp+A /A) / (σp+d /2), are sensitive to the
nuclear eﬀects on anti-quarks.
The SeaQuest spectrometer5) detects the ﬁnal-statemuon pair of the Drell-Yan process. SeaQuest acquired physics data from November 2013 to July 2017with a summer accelerator shutdown each year. It hasrecorded 1.4 × 1018 beam protons on targets and analyzed approximately 40% of the recorded data. We
selected dimuons with the invariant mass larger than
4.2 GeV, for which the Drell-Yan events are dominant. The dimuon yields have been corrected for trackreconstruction eﬃciency and background dimuons byusing the extrapolation method.6)
∗1
∗2
∗3
∗4
∗5
∗6

School of Science, Tokyo Institute of Technology
RIKEN Nishina Center
Faculty of Science, Yamagata University
Institute of Physics, Academia Sinica, Taiwan
Institute of Particle and Nuclear Studies, KEK
College of Science and Technology, Nihon University- 80 -

Fig. 1. Ratios of per-nucleon cross sections of C, Fe, and W
to D versus the Bjorken x of target-side partons (xT ).
The SeaQuest preliminary result is drawn with blue circles, and the E772 result is drawn with red squares.

Figure 1 shows the preliminary result of R(A/D)
measured using SeaQuest, together with the result obtained using E772 for comparison. The systematic uncertainty arises mostly from the ﬁtting shape used in
the extrapolation method. SeaQuest is consistent with
E772 in the commonly measured region, xT ∼ 0.2, with
better accuracy at higher xT . It favors the observationby E772 that the nuclear eﬀects on anti-quarks diﬀer
from those on quarks. Improvements in the measured
precision and comparisons to theoretical models in order to ﬁnalize the result are ongoing.
References

1) J. J. Aubert et al., Phys. Lett. B123, 275 (1983).
2) D. M. Alde et al., Phys. Rev. Lett. 64, 2479 (1990).
3) E. L. Berger, F. Coester, Phys. Rev. D 32, 1071 (1985).
4) A. E. L. Dieperink, C. L. Korpa, Phys. Rev. C 55, 2665
(1997).
5) C. A. Aidala et al., Nucl. Instrum. Methods Phys. Res.
A 930, 49 (2019).
6) K. Nagai et al., 2RIKEN Accel. Prog. Rep. 52, 86 (2019).

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 53

Progress of the polarized Drell-Yan experiment at Fermilab,
SpinQuest (E1039)
Y. Miyachi,∗1 Y. Goto,∗2 K. Nagai,∗2,∗3 K. Nakano,∗2,∗4 G. Nukazuka,∗1 S. Sawada,∗2,∗5 and T. -A. Shibata∗1,∗6
for the SpinQuest Collaboration
SpinQuest is a polarized fixed-target Drell-Yan experiment using a 120 GeV proton beam from Main
Injector at Fermilab. The primary goal of SpinQuest
is to measure the Sivers asymmetries, aiming to obtain a hint for the following fundamental question:“Do the light sea quarks contribute to the intrinsic spinof the nucleon via their orbital angular momentum?”
The Sivers asymmetry was first introduced to explain
the unexpected, large, transverse, single-spin asymmetries observed in hadron scattering. Non-zero valuesof the Sivers asymmetry have been measured in the
Semi-Inclusive Deep-Inelastic Scattering (SIDIS) experiments. The correlation between the transverse momentum of a quark and the spin of the parent nucleon,
represented by the Sivers function, is a source of theasymmetry. The Sivers functions for u and d quarks
were determined to be similar in size but with the opposite signs.2,3) As no results for the Sivers functions
for sea quarks are available, SpinQuest can help deter¯ through the measurement ofmine them for ū and d,
the Sivers asymmetries in the Drell-Yan process using
the transversely polarized proton and deuteron targets,for the first time.
NH3 and ND3 are used as the polarized proton anddeuteron target material. The target polarization is
obtained with dynamic nuclear polarization, which requires a low temperature of 1 K, strong magnetic fieldof 5 T, and 140 GHz microwave radiation. Under
the greatest instantaneous luminosity of any previous
evaporation refrigerator system, with a beam intensity of 3 ×1012 protons/s for 5 s, a high-cooling-power4
He evaporation refrigerator connected to a large pumpsystem (14,000 m3 /h) successfully maintains the target
material temperature at 1 K. The longest (along withthe beam-line) target cell to date for an evaporation
refrigerator requires a unique microwave distributing
horn. Three NMR coils installed for the target cell reduce systematic uncertainties in the polarization measurement.
The SpinQuest experiment inherits the spectrometerfrom the SeaQuest experiments,1) which measured the¯
flavor asymmetry in the light quark sea, d/ū.
It covers
the kinematic region where target sea quarks dominate
the Drell-Yan process: u or d quarks in the beam areannihilated with ū or d¯ anti-quarks in the target, re∗1
∗2
∗3
∗4
∗5
∗6

Fig. 1. Projected sensitivities of the single spin asymmetries at SpinQuest.

spectively. Because SpinQuest probes a lower xtarget
than SeaQuest, the target position has been moved
further upstream of the beam dump to increase acceptance in the low xtarget range, as well as to improveseparation for target and dump events. At present,
the commissioning of the target and spectrometer isongoing. The beam time is expected to begin in early2020.
Figure 1 shows the expected sensitivities of SpinQuest on the single spin asymmetries, AN , after two
years of combined operation on the NH3 and ND3targets. The error bars are statistical only. A relative systematic uncertainty of 0.04 is expected. The
bands represent theoretical predictions based on the
Sivers functions2,3) extracted from the present available SIDIS data. A comparison between the NH3 and
ND3 results could also be sensitive to the flavor dependence of the sea-quark Sivers function.
References

Faculty of Science, Yamagata University
RIKEN Nishina Center
Institute of Physics, Academia Sinica, Taiwan
School of Science, Tokyo Institute of Technology
Institute of Particle and Nuclear Studies, KEK
College of Science and Technology, Nihon University

1) C. A. Aidala et al., [SeaQuest Collaboration], Nucl. Instrum. Methods Phys. Res. A 930, 49 (2019).
2) M. Anselmino et al., Eur. Phys. J. A 39, 89 (2009).
3) P. Sun, F. Yuan, Phys. Rev. D 88, 034016 (2013).

- 81 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 53

Development of zero-degree calorimeter for EIC
Y. Goto,∗1 T. Chujo,∗2 Y. Itow,∗3 J. H. Lee,∗4 H. Menjo,∗5 Y. Miyachi,∗6 I. Nakagawa,∗1 K. Nakano,∗1,∗7
T. Sako,∗1,∗8 R. Seidl,∗1 T. -A. Shibata,∗1,∗7,∗9 K. Tanida,∗1,∗10 and Y. Yamazaki∗11
EIC, physics programs require the tagging of forward
neutrons as spectators to identify the target nucleon.
It constrains kinematics for studies of the short-range
correlation (SRC). The SRC is a nucleon-nucleon interaction at a very short distance. It shows how nucleons form a nucleus, and has a deep connection to
how the quark-gluon structure of a nucleon in a nucleus is modiﬁed, which is a phenomenon known as
the EMC eﬀect.3) Experiments have shown it is universal that ∼20% of nucleons are in SRC pairs. These
SRC pairs have high momentum and are spatially very
close to each other. Almost all of these SRC pairs arefound to be similar to a quasi-deuteron at its highmomentum tail. In addition to the SRC study in electron + nucleus collisions, we will be able to understandthe deuteron as a baseline of the SRC pair in electron+ deuteron collisions at zero degree.
In electron + proton collisions, the leading protonand neutron productions in DIS were measured, andtheir production mechanisms were studied at HERA
by comparison with the fragmentation process andone-pion exchange (OPE) process. The results support that the OPE process dominates the production,
but there are still tension in detailed understanding of
the mechanism and comparison between ZEUS4) andH15) data. In addition to the production cross section measurement, the spin asymmetry measurementof the leading baryons in polarized electron + proton
collisions will give us useful additional information forthe study of the production mechanism. The data
will also be used to understand the energy ﬂow anddevelopment of the event generator, and applied forunderstanding the air shower evolution of high-energy
cosmic rays and the neutrino interaction.
We will conduct the following studies in the future;1) a photon detector study at a low energy <300 MeV,
2) a prototype study of ZDC with position sensitivity,and 3) a radiation hardness study of scintillators. We
would like to maximize the physics capability by studying detector design, development, and simulation.

We propose the development of zero-degree apparatus in the Electron-Ion Collider (EIC) experiment.
Zero-degree detectors play critical roles in a numberof important physics topics at EIC.1) We will study
the requirements and technologies of zero-degree detectors and mainly develop a position-sensitive zerodegree calorimeter (ZDC).
In electron + nucleus collisions, exclusive vector meson production in a diﬀractive process is one of the
key measurements at EIC. For the coherent process
in which the nucleus remains intact, the cross section dependent on the momentum transfer (t) can betranslated to the transverse spatial distribution of gluons in the nucleus and is thus considered to be directly sensitive to the gluon saturation. This requires
accurate determination of the coherence of the reaction, which must be determined by identifying the
breakup of the excited nucleus. Evaporated neutrons
from the breakup in the diﬀraction process can be used
to separate the coherence with the highest probability(∼90%). In addition, photons from the de-excitationof the exited nucleus signal incoherence in the absenceof evaporated neutrons. This leads to a requirement tomeasure neutrons and photons precisely at near zero
degree to complete the coverage of coherence tagging
in a wide t range.
Collision geometry is an important measure in electron + nucleus collisions for an event-by-event characterization. It has been proposed that collision geometries can be tagged through forward neutron multiplicities emitted at near zero degree.2) Constraining
collision geometry quantities such as the “travelinglength” of the struck parton in the nucleus, which iscorrelated with the impact parameter of the collision,is very meaningful in studies of nuclear medium effects. With the determination of collision geometry inthese measurements, higher-precision constraints canbe achieved to enhance our understanding of the nuclear structure.
In electron + deuteron and helium-3 collisions at∗1

RIKEN Nishina Center
Tomonaga Center for the History of the Universe, Universityof Tsukuba∗3 Institute for Space-Earth Environmental Research, Nagoya
University∗4 Physics Department, Brookhaven National Laboratory∗5 Graduate school of Science, Nagoya University∗6 Department of Physics, Yamagata University∗7 Department of Physics, Tokyo Institute of Technology∗8 Institute for Cosmic Ray Research, University of Tokyo∗9 College of Science and Technology, Nihon University∗10 Advanced Science Research Center, Japan Atomic Energy
Agency∗11 Graduate School of Science, Kobe University

References∗21) A. Accardi et al., Eur. Phys. J. A 52, 268 (2016)[arXiv:1212.1701 [nucl-ex]].
2) L. Zheng, E. C. Aschenauer, J. H. Lee, Eur. Phys. J. A
50, 189 (2014) [arXiv:1407.8055 [hep-ex]].
3) B. Schmookler et al., [CLAS Collaboration], Nature
566, 354 (2019).
4) S. Chekanov et al., [ZEUS Collaboration], Nucl. Phys.
B 776, 1 (2007) [hep-ex/0702028].
5) F. D. Aaron et al., [H1 Collaboration], Eur. Phys. J. C
68, 381 (2010) [arXiv:1001.0532 [hep-ex]].

- 82 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 53

INTT Silicon Modules and Ladders Assembly for sPHENIX Project
C. Miraval,∗2 Y. Akiba,∗1 K. Cheng,∗3 E. Desmond,∗2 T. Hachiya,∗1,∗4 T. Kondo,∗5 C. Kuo,∗3 M. Lenz,∗2
E. Mannel,∗2 D. Cacace,∗2 M. Morita,∗4 I. Nakagawa,∗1 R. Nouicer,∗2 R. Pisani,∗2 M. Shibata,∗4 C. Shih,∗3
A. Suzuki,∗4 T. Todoroki,∗1 X. Wei,∗6 and R. Xiao∗6
The INTermediate silicon strip Tracker (INTT) barrel is comprised of several ladders tangentially arranged in layers around the RHIC beampipe.1) Eachladder assembly has two high-density interconnects(HDI) that are epoxied to a carbon fiber stave support. The two HDIs collectively host 52 FPHX chips
and 4 silicon sensors. The sensors and the chips are
glued to pads on the HDIs, wire-bonded, and then encapsulated.
The assembly process consists of multiple steps (cf.
Fig. 1). During the inspection step of assembly, thecarbon fiber staves are measured for flatness on BNL’s
OGP Smartscope Flash 500. The OGP is a top-downlaser optical measurement system with a potential Z
accuracy of 2 microns. Qualified carbon fiber staves
are placed on the assembly fixture (cf. Fig. 2) and HDIs
are installed and epoxied using glue masks.
Glue masks are placed in order to accurately epoxy
to the chip pads on the HDIs. Chips are then precisely
located and placed with acrylic vacuum fixtures thatinterface with the main assembly fixture (cf. Figs. 3–5). After the chips are epoxied, they are wire-bonded
to the HDIs and then electronically tested.
In the same fashion that the chips were installed, thesilicon sensors are placed on epoxied locations along
the HDIs using vacuum fixtures. The sensor’s vacuum
fixture (cf. Figs. 4 and 5) has micro adjusters allowing
the sensor’s position to be perfected before the epoxy
cures. Small marks are referenced on the HDI and thesilicon sensors using the OGP machine. These marks
are used for live alignment checks while adjusting thepositions of the sensors. After the epoxy is cured, afinal wire-bond job is performed and the full assemblyis then electrically tested.
Currently, all assembly fixtures have been designed, fabricated, and received; permitting us to begin prototype production. Additional fixtures usedin transportation and wire-bonding/encapsulation are
designed and being sent for fabrication. The transportation container doubles as a safe storage and testing fixture, as the electronic connectors and the cooling pipe can be accessed from outside the transportation container without putting the delicate sensors andchips at risk. Specific fixtures were necessary for the
∗1
∗2
∗3
∗4
∗5
∗6

wire-bonding and encapsulation machines so that multiple staves can be produced in the same exact manner
every time, streamlining production.

Fig. 1. Assembly Steps.

Fig. 2. Assembly Fixture.

Fig. 3. Chip Placement Tools on Assembly.

Fig. 4. Sensor Placement Tools on Assembly.

Fig. 5. Chip Placement Tool and Sensor Placement Tool

RIKEN Nishina Center
Brookhaven National Laboratory
National Central University
Nara Women’s University
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University

Reference

1) Conceptual Design Report of sPHENIX (2018).

- 83 -

6. Particle Physics

Ⅱ-6. Particle Physics

RIKEN Accel. Prog. Rep. 53

Empirical formulas for the standard-model parameters
Y. Akiba,∗1
Table 2. Formulas of the CKM matrix elements Vus , Vcb ,Vub , and the CP-violation parameter η̄.

In my previous article,1) I reported empirical formulas of the masses of the elementary particles inthe standard model (SM), namely, charged leptons(e, µ, τ ), quarks (t, c, u, b, s, d), gauge bosons (Z, W ),and the Higgs boson (H). Each of these formulas yields
the ratio µp /Mpl of the mass of particle p to the Planck
mass Mpl = 1.220910 ± 0.000029 × 1019 GeV in termsof a dimensionless constant ϵ0 = 2 × (6π)−48 . There isno adjustable parameter in the formulas.
Here, I report similar formulas for the mass of neutrinos, Cabbibo-Kobayashi-Masukawa (CKM) quark
mixing parameters, and neutrino mixing parameters.
Table 1 lists mass formulas including neutrions. The
neutrino masses calculated from the formulas are m1 =2.70 × 10−3 eV, m2 = 9.01 × 10−3 eV, and m3 =5.09 × 10−2 eV. Table 2 shows the formulas for the
CKM matrix elements and their calculated values. Table 3 lists the formulas of the neutrino mixing parame-

Vus
Vcb
Vub
η̄

s12

Table 1. Formulas for the masses of the SM particles.
s13
e
µ
τ

ν1
ν2
ν3
t
c
u
b
s
d

Z
W
H
∗1

(

calculated
0.224450.04332
0.003753
0.3497

Table 3. Formulas of the neutrino-mixing matrix.

s23

particle p

formula)−1 )1/2
1
1
1+
6π
6π
( )1/221
36π
4 1
3 (6π)2
(
)
3 1
1
27 1
1+
+
2 6π
4 (6π)2 π(

formula (µp = mp /Mpl )
(
)−1
1 1/3
1 1
ϵ
1
+
12π 2( 04 (6π)2 )
−1
3 1/3
3
27 1
1−
ϵ0
+
2
6π
4 (6π)2 )
(
−1
3 1
5 1
1/3
9πϵ0
1−
+
2
4 6π
4 (6π)

formula( ()()−1 )1/2
1
1
1
1−
1+
3
6π
6π
(
(
)(
)−1 )1/2
3
1
1
1+
1−
2π
6π
6π
(
)1/2 (
)(
)−1
1
1
1
1−
1+
12π
6π
6π

calculated
0.547
0.729
0.146

ters and their calculated values. The values calculated
from these formulas all agree with experimental data
within the uncertainty of the data.
There are 25 free parameters in the SM. These formulas yield 22 out of the 25 parameters. The remaining 3 parameters are the fine structure constant α, thestrong coupling constant αs , and the neutrino CP violation parameter δCP . Both α and αs are scale dependent, and δCP is the only unmeasured parameterin the SM.
Note that the value of ϵ0 is consistent with the product of the Hubble constant H0 and the Planck time
tpl = 1/Mpl :

(
)−1
1
2 1/2
1+
ϵ0
3
6π )
(
−1
1
1/2
2ϵ0
1−
6π )
(
−1
1
1/2
4πϵ0
1+
6π
1/3

8(6π)2 ϵ01/3
12ϵ0−2 1/38(6π) ϵ0
(
)−1
27 1
3 1
1/3
3(6π)ϵ0+1+
2 6π
4 (6π)2
1/3
ϵ0
(
)−1
1
−1 1/3(6π) ϵ01+
6π

H0 × tpl = (1.211 ± 0.014) × 10−61 .

ϵ0 ≡ 2 × (6π)−48 = 1.220608 × 10−61 .
Here, the Wilkinson Microwave Anisotropy Prob
(WMAP) nine-year value of H0 is used. This suggeststhat the masses of elementary particles are related tothe expansion of spacetime.
A model to explain these formulae is reported in thenext article,2) and implications to gravity and cosmology are reported in the article appearing after that.3)

)−1/2
(
1 1/4
1 1
1 1
ϵ
+
1
+
0
(8π 2 )12 6π
12 (6π)2()−1/2
2−1/4 1/4
3 1
9 1
ϵ
1−
−
(8π 2 02 6π
4 (6π)2
(
)−1/2
1/2
2
3 1
9 1
1/4
ϵ
1
+
−
8π 2 02 6π
2 (6π)2

References
1) Y. Akiba, Accel. Prog. Rep. 52, 98 (2019).
2) Y. Akiba, in this report.
3) Y. Akiba, in this report.

RIKEN Nishina Center- 85 -

Ⅱ-6. Particle Physics

RIKEN Accel. Prog. Rep. 53

Quarternion-spin-isospin model for the standard-model parameters
Y. Akiba ∗1
Table 1. Elementary actions.

In the preceding article,1) empirical formulas of theparameters of the standard model (SM) of particle
physics are presented. Here, I report a model thatcan produce these formulas. We call the model the“Quarternion-spin-isospin model” since it is based on
operators that are products of the quarternion bases
I µ , spin operator σ ν , and (weak) isospin operator
τ a . In the model, the Planck time τpl = 1/Mpl =5.3912 × 10−44 s is the minimum duration of time. A
term of the Lagrangian density Li of a particle is an“oriented product” of 48 “normalized primordial actions” (NPAs) that are selected from the following 64
NPAs.
}{ I µ σ ν τ a i τ 3 I c τ 3 −I c −i
,
,
,
,
,
, i, I c , −2, 2, 16π
3π 3π 3π 2π π
The oriented product operator ∨ has the following reduction rules:{α̂β̂, (if α̂β̂ = −β̂ α̂)α̂ ∨ β̂ =0,(if α̂β̂ = β̂ α̂){α̂β̂γ̂, (if α̂β̂ = −β̂ α̂, β̂γ̂ = −γ̂ β̂, γ̂ α̂ = −α̂γ̂)α̂∨ β̂ ∨γ̂ =0,(otherwise)(6π)2 ϵ0
iτ 3
i
g3D
g2D
Gab
e
µ
τ
ν1
ν2
ν3
U
u
c
t
D
d
s
b
Z
H
W

4
4
4
12
−4
12
−12
4
4
4
−12
−12
−12
4

−12
−3

1

3

iτ 3

ϵ0
i

−24
1
27
1+4

12
12

1
3
2
3
3
2
2

4
−2 2

2
8
24
8
1

−12

3

6
1
6

3

12
−4

(6π)ϵ0
i
τ3

3

−18

12

27
1

18
18
18
−27 18

1/3∂ˆ16 = ϵ0 (1 + iσ 1 + iσ 2 + iσ 3 ),s ∨ α̂ = sα̂, s1 ∨ s2 = 0, α̂ ∨ s ∨ β̂ = sα̂β̂.

+
+ 2
+ 3
1
= |ψ15 |τ + (u+ψ̂15
1 σ + u2 σ + u3 σ ),Here, s is a scalar. Following these rules, a 48
∨ product of NPAs, dS = ŝi1 ∨ · · · ∨ ŝi48 , is re′duced to a value in the form of ±m(6π)n is (τ 3 )s ϵ0 ,where ϵ0 = 2 × (6π)−48 , s ∈ {0, 1}, s′ ∈ {0, 1},m ∈ {1, ±2, ±3, ±4, ±6, ±8, ±12, ±18, ±24}, and n ∈{0, 1, 2}. The values of s, s′ , n, and m are determinedby the selection of the subset {ŝ1 , · · · , ŝ48 } from SNPA .
Due to the calculation rules of the ∨ product, only alimited number of 48 products have a non-zero reduced
value. We call these non-zero 48 product the “elementary action” (EA). An EA corresponds to a term of
Lagrangian density L of an elementary particle, e.g.,
the electron.
We found 48 EAs that correspond to the elementary particles of the SM, which are summarized in Table 1. In the table, U and D denote U -type and D-type
quarks, respectively, when their masses are ignored.
The mass of particles can be obtained from Table I.
In the following, I show how the mass formula of theelectron can be obtained from the table as an example.
The Lagrangian of the electron is a sum of three
EAs.

−
− 2
− 3
1
= |ψ15 |τ − (u−ψ̂15
1 σ + u2 σ + u3 σ ),1/3

Â18 = (6π)−2 ϵ0 (1 + iσ 1 + iσ 2 + iσ 3 ).
1/3Here, |ψ15 | = (6π)ϵ0 and the 3D vectors u+ =
+
+
−
−
−
−
+
−
(u+
1 , u2 , u3 ) and u = (u1 , u2 , u3 ) satisfy u × u =(−1, −1, −1) and u+ · u− = 1. The operators ∂ˆ16 and−correspond to the diﬀerential operator iσ µ ∂µ andψ̂15+
corresponds to its
the electron ﬁeld operator, and ψ15
conjugate. One can show
)(
(
)
1 1
ˆ16 ψ̂ + ψ̂ − + µe |ψ15 |2 ,∂L̂e = 1 +15 15
4 (6π)2
(
)−1
1 1/3
1 1
ϵ .
µe = 1 +
4 (6π)2
12π 2 0Similarly, all of the 22 formulas of the SM parameterspresented in the preceding article are derived. The
model also predicts 100% CP violation in the neutrino
sector and that the product of the Hubble constant H0
and the Planck time tpl is H0 tpl = 2 × (6π)−48 .
ReferenceL̂e = 4(6π)2 iϵ0 τ 3 + iϵ0 iτ 3 + 3ϵ0 .

1) Y. Akiba, in this report.

Each EA can then be written as a product of the following “operators.”
∗1

iτ 3

RIKEN Nishina Center- 86 -

Ⅱ-6. Particle Physics

RIKEN Accel. Prog. Rep. 53

R = 12H02 and its implications to gravity and cosmology
Y. Akiba ∗1
In the preceding article,1) I report a model (QST
model) that can yield the formulas of the standard
model (SM) parameters. The model implies that the
product of the Hubble constant H0 and the Plancktime tpl is H0 tpl = 2 × (6π)−48 = ϵ0 . This relation isderived as follows.
In general relativity, the action is written as
∫
∫ √
√
4
S = L −gdx = L det(gµν )d4 x,

which means that ϕ satisties the Laplace equation.
The general solution of ϕ isϕ(⃗r) = 1 − Σi

We note that ϕ2 = e2u = −g00 . In general relativity, g00 ≃ −1 − 2ϕG , where ϕG is the gravitational
potential. This means that ϕ = ϕG . Thus, the relation
R = 0 implies the Coulombic gravitational potential.
If we take into account the fact that H0 ̸= 0, thepotential equation for gravity becomes non-linear.

where gµν is the metric and L is the Lagrangian densityof the system.
In the QST model, this is expressed as√(1 + L̂) −g = 1 + L̂ + L̂g3D∆ϕ + 6H02 e2H0 t (ϕ − 1/ϕ) = 0.
One may question the validity of the QST model,
since the model implies that the Hubble constant is aconstant, which would mean that spacetime expands
exponentially at a constant rate. This contradicts
standard Big Bang cosmology. In the Big Bang theory,
H0 is not constant, and the scale of the universe is zeroat the Big Bang, which supposed to have occurred 13.8
billion years ago.
We note that there is no direct evidence that the Big
Bang occured 13.8 billion years ago, because the absolute scale of the time coordinate in the past is impossible to determine. The distance to an object far away
can only be measured by the red shift z. The valueof z is then translated to the time based on standard
cosmology by using the Friedmann equations. However, there is no experimental method to verify thatthe translation from z to t is correct.
The cosmic microwave background (CMB) is usuallyconsidered as the direct evidence of the Big Bang. I
argue that it is not. CMB is definitive evidence that
there was an era of z = 1100 when the spacetime scaleis 1/1100 of the present one and the temperature of
the Universe was 3000 K. In the standard cosmology, z = 1100 translates to 13.8 billion years ago and
380,000 years after the Big Bang. However, the only
basis for this time scale is the Friedmann equations. If
we assume that H0 is constant, the only change is thatthe time of CMB formation becomes about 1 trillion
years ago instead of 13.8 billion years ago.
The agreement between the abundance of 4 He andthe Big Bang nucleosynthesis (BBN) model is considered another evidence of the Big Bang. In standard
cosmology, BBN occured 3 minutes after the Big Bang.
However, it is impossible to determine the absolute
time when BBN occured. There is no observation that
contradicts with the assumpition that H0 is constant.

where L̂ is the elementary action (EA), and L̂g3D = 3ϵ0
is the EA corresponding to the gravity.
√−g = 1 + L̂g3D = 1 + 3ϵ0
Now the spacetime metric of the Hubble expansion is
ds2 = −dt2 + e2H0 t (dx2 + dy 2 + dz 2 ).
√For t = tpl , we have −g = e3H0 t = 1 + 3H0 tpl . Fromthe comparison, we have H0 tpl = ϵ0 . The Ricci scalar
curvature R and the 3D curvature K of this metric are
R = 12H02 ,K = 0.
Since H0 = ϵ0 /tpl is a constant, R is also a constant in
the QST model.
Now, we generalize the metric to allow local changesof the scale with a constraint that Ricci curvature
should remain constant.
ds2 = −e2u(x,y,z) dt2 + e2H0 t (dx2 + dy 2 + dz 2 ),R = 12H02 .

The Ricci curvature of this metric is
R = −2(∆u + (∇u)2 )e−2H0 t + 12H02 e−2u = 12H02 .
We can show that Coulomb gravity can be derived
from this metric. When we take the approximation
H0 ≃ 0, we have
R = −2(∆u + (∇u)2 ) = 0.
Now, we define ϕ = eu ; thus, we have
∆ϕ = ∆(eu ) = (∆u + (∇u)2 )ϕ = 0,
∗1

rsi
.
|⃗r − r⃗i |References
1) Y. Akiba, in this report.

RIKEN Nishina Center- 87 -

7. Astrophysics and Astro-Glaciology

Ⅱ-7. Astrophysics and Astro-Glaciology

RIKEN Accel. Prog. Rep. 53

Experimental equipment for exploring reactions of low energy ionswith an ice surface as an interstellar dust analog
Y. Nakai,∗1 H. Hidaka,∗2 and N. Watanabe∗2
An understanding of the synthesis of interstellar
molecular evolution is indispensable for understanding
various chemical aspects in the universe, e.g., the originof life. Various kinds of molecules have been found evenin molecular clouds in the first stage of star formation,
despite their very low temperature. Gas-phase ionmolecule reactions have been always considered to play
an important role in the chemical evolution in molecular clouds. Reactions of neutral radicals with neutral
species on an icy grain surface have been also proposed
as other pathways, the importance of which has been
confirmed for the production of hydrogen molecules,
water molecules, methanol molecules, and so on.1) Recently, the reactions of very-low-energy (eV order) ionswith an icy surface have been theoretically proposed tobe new non-negligible reaction pathways. In most of
the proposed pathways, neutral species and H3 O+ ionsare produced on the surface through reactions involving multiple water molecules.2,3) These reactions are
extremely complicated compared with gas-phase reactions. In addition, an actual icy surface probably has
more variety and complexity than the theoretical assumptions. Therefore, experimental investigations are
crucial to confirm theoretical predictions and explore
such reactions more deeply. However, no experiments
have been reported to our knowledge. Thus, we havestarted developing an experimental apparatus. In thisreport, we will provide an overview of our apparatus
under development.
Figure 1 shows a schematic of our experimental
equipment. An amorphous solid water (ASW) film
is made on an aluminum substrate mounted on thecold head of a He refrigerator at a low temperature(∼10–50 K) by introducing water vapor of ∼1 ×10−5
Pa into the vacuum chamber. The thickness of the
ASW film is estimated from its infrared absorption
intensity, which is measured using Fourier-transform
infrared spectroscopy (FTIR). After the introductionof water vapor is stopped, the ASW surface is irradiated with low-energy atomic/molecular ions using theion source located at the front of the substrate (lowenergy ion source in Fig. 1). This ion source consists ofan electron-impact ionizer, a Wien filter in which theions are mass-analyzed, and a deceleration lens system
to decelerate and focus ions on the substrate. In thetest of the ion source using a N+
2 beam, we obtained
an intensity of ∼2.8 nA with an energy of ∼3 eV andan energy spread of approximately ±2 eV on the substrate.
∗1∗2

Fig. 1. Schematic drawing of the experimental setup.

Our apparatus has another ion source (Cs+ ion
source in Fig. 1) for detecting reaction products by theirradiation of low-energy atomic/molecule ions. The
detection method is based on reactive ion scattering(RIS) and low-energy ion sputtering (LES) by Cs+
ions with a kinetic energy of a few or several tensof eV, which has been mainly developed as a detection method for neutral and/or ionic species on metal
and ice surfaces at temperatures higher than ∼70 K.4)
When Cs+ ions collide with an ice surface, a part ofthem pick up neutral species including water moleculeson the surface and scattered composite ions of CsM+
(RIS), where M is a picked-up neutral species. We canobtain a mass of M from the mass analysis of scattered CsM+ ions. Moreover, we can obtain the massesof ionic species on the surface through the mass analysis of ions sputtered by Cs+ (LES). A quadrupole mass
analyzer is used for these mass analyses. At present,
we performed isolated tests of the RIS method using apristine ASW film at 30 K and could detect Cs(H2 O)+
ions from the RIS process. However, the detection sensitivity will be further improved for our purpose.
We are now continuing development of the lowenergy ion source and the RIS-LES method for the
ASW surface at low temperature, aiming for better
performances.
References

1) N. Watanabe, A. Kouchi, Prog. Surf. Sci. 83, 439(2008).
2) D. Woon, Astrophys. J. 728, 44 (2011).
3) E. J. McBride et al., J. Phys. Chem. A 118, 6991 (2014).
4) H. Kang, Bull. Korean Chem. Soc. 32, 389 (2011).

RIKEN Nishina Center
Institute of Low Temperature Science, Hokkaido University- 89 -

Ⅱ-7. Astrophysics and Astro-Glaciology

RIKEN Accel. Prog. Rep. 53

Commissioning of a prototype novel laser melting sampler for analyzing
ice cores with high depth resolution and high throughput
Y. Motizuki,∗1 Y. Nakai,∗1 M. Yumoto,∗2 M. Maruyama,∗2 K. Takahashi,∗1 K. Kase,∗2 S. Wada,∗2 J. Hirose,∗1 andY. Yano∗1
A new facility for analyzing ice cores is being developed jointly by the Astro-Glaciology Research Group(AGRG) of RIKEN Nishina Center and the Photonics Control Technology Team of RIKEN Center for Advanced Photonics in a room (50 m2 ) at Wako Campus.
The mission of this facility is to analyze ice cores withhigh depth (temporal) resolution and high throughput
to obtain concentration proﬁles of various isotopes such−as 18 O/16 O and various ions such as SO2−
4 and NO3 .
The ice cores that we study have been drilled by
the Japanese Antarctic Research Expedition (JARE)
around Dome Fuji (DF) station in East Antarctica, andthe current JARE project to obtain the third Japanese
deep ice core, which is expected to contain information
up to more than a million years ago, has been approved
and is in progress. We aim at investigating the longterm history of climate change from the viewpoints of
the relation with solar activities and volcanic eruptions.
We also seek traces of supernovae in our galaxy and its
explosion rate as our ﬁnal goal.
In our facility, a low-temperature (LT) room, i.e., aprefabricated freezer container (3 m wide × 5 m long× 3 m high), has been installed, and its inside has been
kept at −20◦ C. Outside the LT room, two sets of isotope
analyzers have been equipped at room temperature; weplan to add the newest ion chromatography system here
in the near future.
The application of the laser melting method on ice
cores to obtain samples is the ﬁrst in the world. Figure 1 depicts a schematic of the prototype laser melting
sampler. The sampler consists of a continuous-wave ﬁber
laser (λ = 1.55 µm), an optical ﬁber (core diameter =200 µm, our originally designed nozzle (2 mm outer ϕ),a sampling buﬀer system with an electromagnetic valve,
and a computer that controls the positions of the sampling nozzle and the motorized stage on which an ice coreis placed. This system makes it possible to analyze ice
cores at a high depth resolution of ∼2 mm scale, whichcorresponds to a temporal resolution of ∼1 month in thecase of a DF ice core. Our system is also applicable to a
1-year resolution (∼3 cm) when sampling is performedin the direction of core depth.

Fig. 1. Schematic of the ice-core laser melting sampling system.
∗1∗2

Fig. 2. Left ﬁgure shows a photo of melting ice with thenozzle intruding the dummy ice (bottom right) and theinside buﬀer being ﬁlled (bottom left). The right shows
a ﬁlled vial.

In Fig. 1, the laser beam delivered by the opticalﬁber irradiates the target ice-core surface, and 1.5 mL of
melted water (suﬃcient volume for our precision analysis) is sucked up through the nozzle and transported
into our original SUS vial bottle by a peristaltic tube
pump at a pressure drop of 1 atm. The nozzle and tube
are kept above 0◦ C by the heaters installed inside thenozzle assembly.
We succeeded in continuous sampling into the vials
using this prototype sampler. Figure 2 shows the result: the holes were vertically made as small as 2 mm ϕon a dummy ice block (ρ = 0.9 g/cc) by laser melting.
For this purpose, a laser beam with a power of ∼1.3 W
was irradiated, and the nozzle intruding speed was set
to 0.40 mm/s. The eﬃciency of collecting melted water
was estimated to be ∼100%. As the ﬁrst step, we set ourtarget sampling time for a vial to 20 min, which was determined in concordance with the measurement time of
one sample by a single isotope analyzer using the AGRG
protocol developed based on our isotope measurements.
By choosing optimum apparatus parameters and by using an automated multi -nozzle system that has alreadybeen equipped in our system, we plan to attain a higher
throughput to handle many sample vials.
Our new technique has some advantages in comparison with the standard heater-melting continuous ﬂow
analysis method.1) They are as follows: 1) samplingzones are discrete to avoid mixing with each other, 2)
the amount of sampling ice can be adequately minimized, and 3) fragile low-density ice cores are also applicable because the portion of a core is placed horizontally (Fig. 1). Making the most of these merits, we havestarted to perform our ﬁrst application on Antarctic ice
to study if there appear seasonal variations in the wellestablished temperature proxy (18 O/16 O) for the ﬁrst
time in the past ∼30 years for direct comparison withthe temperature measured in the area.
We are grateful to Michio Sakashita for supporting uswith laser ﬁber treatment and Yu Vin Sahoo for preparing clear dummy ice blocks suitable for our experiments.
Reference

RIKEN Nishina Center
RIKEN Center for Advanced Photonics

1) e.g., R. Dallmayr et al., Bull. Glaciol. Res. 34, 11 (2016).
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Revaluation of beam orbit calculation method for the injection line of
AVF cyclotron after tuning pepper-pot emittance monitor
Y. Kotaka,∗1 Y. Ohshiro,∗1 H. Yamaguchi,∗1 N. Imai,∗1 Y. Sakemi,∗1 T. Nagatomo,∗2 T. Nakagawa,∗2 M. Kase,∗2
J. Ohnishi,∗2 A. Goto,∗2 K. Hatanaka,∗3 H. Muto,∗4 and S. Shimoura∗1
We developed a calculation method for the beam orbit from the Hyper ECR ion source to the AVF cyclotron
using the 4D emittance measured by a pepper-pot emittance monitor1) named PEM_IH102,3) and evaluated itwith the degree of ﬁt, which is χ2 divided by the degree of freedom (DOF) between two projections to anarbitrary coordinate axis made from both the measurement of other diagnostics and the beam orbit calculation.
However, the dispersion of χ2 is assumed to be the squareof 10% of the highest value of the measurement. Subsequently, the method of processing the beam image on
the ﬂuorescent plate of PEM_IH10 recorded by a digital camera was improved.4) This report is a summary ofRef. 4).
This year, as it was found that the degree of ﬁt varied
at diﬀerent thicknesses of the ﬂuorescent agent, the variation of the degree of ﬁt was examined while varying the
combination of the exposure time and gain and the thickness. The results of beam orbit calculations are compared with the beam proﬁle monitor (BPM), which measures 3 axes of proﬁles set 867 mm behind PEM_IH10
using the 23.6-keV 4 He2+ ion beam of 100 eµA. In thistest, the degree of ﬁt is deﬁned by dividing the sum of 3axes of χ2 by the sum of 3 axes of DOF. The thickness isdeﬁned by dividing the weight by the area and density.
The upper and lower tables of Fig. 1 show the degree ofﬁt obtained from thickness of 1.9 and 34.6 µm, respectively. From these results, irrespective of the thickness,the measurement of PEM_IH10 can be homogenized if
the gain and exposure time are optimized.
In order to revalue the beam orbit calculation method
after the optimization with respect to the thickness of thehe ﬂuorescent agent, the degree of ﬁt is examined using 4
beam intensities (124, 187, 196, and 308 eµA) of 15.4 keV

Fig. 1. Degree of ﬁt compared with BPM when the thicknessof the ﬂuorescence agent and the exposure time and gainof the digital camera are varied. (top) thickness = 1.9 µm;(bottom) thickness = 34.6 µm.
∗1
∗2
∗3
∗4

Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center
RCNP, Osaka University
Center of General Education, Tokyo University of Science,
Suwa

Fig. 2. Scatter plots showing the degree of ﬁt of (left) (u, u’)and (right) (w, w’) compared with EM_I36.

Fig. 3. Scatter plot showing the degree of ﬁt of (u, w) compared with a BPM set 107.5 mm behind EM_I36.

He2+ , 100 eµA of 12.6 keV 2 H+ , and 214 eµA of 12.8 keV
H+ by comparing the measurement of a 2D emittancemonitor5) (EM_I36) set 6.2 m behind PEM_IH10 withu and w coordinate axes perpendicular to the beam direction. The angles of u and w are indicated by u’ andw’, respectively. The left and right of Fig. 2 show the
scatter plot of the degree of ﬁt of (u, u’) and (w, w’)of EM_I36, respectively. The u or w values of all samples are less than 4. However, 3 samples showed u’ or
w’ values are greater than 6, and their widths of angular distributions from the beam orbit calculations were
all smaller than those from the measurements for both uand w.
On the contrary, Fig. 3 shows the scatter plot of degreeof ﬁt of (u, w) of BPM set 107.5 mm behind EM_I36.
It is found that all the degrees of ﬁt are less than 4.2.
This reason is not clear yet. We will check the tendencywith more data. On the whole, the results of beam orbit
calculation using 4D emittance measured by PEM_IH10
agree with real beam orbit so that they are useful for
analysing real beam orbits.
4
2

References

1) T. Hoﬀmann et al., AIP Conf. Proc. 546, 432 (2000).
2) Y. Kotaka et al., Proc. 13th Annual Meeting of PASJ,(2016), pp. 1072–1075.
3) Y. Kotaka et al., Proc. 14th Annual Meeting of PASJ,(2017), pp. 1118–1122.
4) Y. Kotaka et al., Proc. 16th Annual Meeting of PASJ,(2019), pp. 1109–1113.
5) Y. Kotaka et al., RIKEN Accel. Prog. Rep. 41, 96 (2008).

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RIKEN Accel. Prog. Rep. 53

Non-thermal equilibrium eﬀect on plasma window with large diameter
N. Ikoma,∗1,∗2 Y. Miyake,∗1 M. Takahashi,∗1 H. Okuno,∗1 S. Namba,∗3 K. Takahashi,∗2 T. Sasaki,∗2 andT. Kikuchi∗2
The disposal of high-level radioactive waste (HLW)
is a serious social problem. To address it, a transmutation scheme of long-lived ﬁssion products (LLFP)
employing a high-power accelerator, which provides
deuteron beams of 400 MW, was proposed in the ImPACT Fujita program.1) In such a system, a beam window, which separates the accelerator and target region,is considered one of the key issues. A plasma window (PW),2) which exploits a large pressure gradient
generated by an arc plasma ﬁlling the discharge channel, is considered a promising candidate. However, theﬁrst PW invented by Hershcovitch2) had an apertureof 2.36 mm, while the beam-spot size required in ourcase is 100 mm or larger.
Therefore, we developed a PW with a maximum diameter of 20 mm, as shown in Fig. 1, and demonstrated
conductance reduction by the PW.3) Furthermore, acomparison between the achieved cell pressure Pcell
and the pressure estimated from Eq. (1)4,5) suggested
that the gas (or heavy-particle) temperature Th was
lower at larger diameters due to the low-input power
density.3)√√
16ηkTh QL
Pcell ≃
,
(1)
πmh
r2

Fig. 2. Te vs. PW diameter.

In this paper, the typical electron temperature Te
was estimated based on the report that the axial electron temperature variation in cascade arc devices issmall.6,7) The Te is described by the Spitzer formula:
(
)2/3
ln Λ
σ
,
(2)
Te ≈
2 × 104

where σ is the average electrical conductivity of theplasma obtained from discharge current, voltage, andgeometry of the channel, assuming a uniform cylinder.
The Coulomb logarithm ln Λ was assumed as 10.
In contrast with the tendency of the heavy-particle
temperature,3) the estimated Te shown in Fig. 2 wasalmost constant regardless of the diameters. This may
indicate that the temperatures of electrons and heavy
particles attain a non-equilibrium state as the diameterincreases. Because Th is the most important factor in
the performance of the PW as described by Eq. (1),the non-equilibrium eﬀect will be discussed with theconductance-reduction eﬀect of plasma ignition.
This work was supported by RIKEN Junior Research Associate Program. Furthermore, this work was
funded by ImPACT Program of Council for Science,
Technology and Innovation (Cabinet Oﬃce, Government of Japan).

where η, k, mh , Q, r, and L are the viscosity of the gas,
Boltzmann constant, mass of gas particles, mass ﬂow
rate, channel radius, and channel length, respectively.

References

1) H. Okuno et al., Proc. Jpn. Acad. Ser. B 95, 430 (2019).
2) A. Hershcovitch, J. Appl. Phys. 78, 5283 (1995).
3) N. Ikoma et al., Plasma Fusion Res. 14, 1206148 (2019).
4) W. A. J. Vijvers et al., Phys. Plasmas 15, 093507(2008).
5) S. Huang et al., Phys. Plasmas 21, 123511 (2014).
6) J. J. Beulens et al., Phys. Fluids B 3, 2548 (1991).
7) J. J. Beulens et al., Plasma Sources Sci. Technol. 2, 180(1993).

Fig. 1. Structure of the PW developed in this study.
∗1
∗2
∗3

RIKEN Nishina Center
Graduate School of Engineering, Nagaoka University ofTechnology
Graduate School of Engineering, Hiroshima University- 92 -

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RIKEN Accel. Prog. Rep. 53

Status report on update of alarm system and control system of magnet
power supplies for RIBF
M. Komiyama,∗1 A. Uchiyama,∗1 M. Fujimaki,∗1 M. Hamanaka,∗2 M. Nishimura,∗2 and N. Fukunishi∗1
We report the following two improvements of the RIBF
control system. The ﬁrst is the update of an alarm system, which supports the stability of beam delivery. The
second is an improvement of the performance of the newmodule for the control system of magnet power supplies: NIO-C developed as a programmable logic controller (PLC) module.
In the RIBF facility, an alarm system has been operated along with the beam interlock system (BIS).1) We
have applied an alarm system mainly to signals indicating abnormal conditions of hardware of the accelerator facility that may adversely aﬀect accelerator tuning.
We are monitoring the status of the following equipmentwith an alarm system now:
(1) Vacuum pumps and valves associated with thepump system, such as the on/oﬀ status of turbo
molecular pumps on beamline.
(2) Vacuum pressure at the cyclotrons and beamline.
(3) Various devices in the AVF cyclotron and its ion
sources, such as the on/oﬀ status of the radio frequency (RF) system and status of current from themagnet power supply for the main coil.
The numbers of signals from the equipment listed aboveare 198, 74, and 18, respectively.
The alarm system has been operated using a tool in
the Control System Studio (CSS)2) and the Best Ever
Alarm System Toolkit (BEAST).3) The BEAST is a distributed alarm system consisting of Alarm Server, a CSS
user interface (UI) for viewing current alarms, and a
relational database for conﬁguration and logging. The
BEAST was ﬁrst introduced in the RIBF control system
in 2012, and it has been actively used in recent times
at the AVF console in the RIBF control room. As the
AVF console was moved to a new location in the summer of 2019, we updated the platform that operates theAlarm Server and relational database from a dedicatedPC to a server running CentOS 7 in a virtual machine
to ensure its stable operation. The BEAST was also updated to the latest version. The latest version of the
CSS software has undergone major improvements overthe previous version in the connection method for experimental physics and industrial control system (EPICS)4)
process variables (PVs). We newly employed CSS version 4.5.0 for the Alarm Server and PostgreSQL version
9.2.24 for the relational database, and CSS version 4.5.8
was newly installed on client PCs. In addition, withreference to the case of KEK, EPICS PVs dedicated tothe alarm system are created separately from the EPICS
PV used to control the equipment. They are operated
on the EPICS input-output controller (IOC) dedicatedto the alarm system. Changing the EPICS PV often∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

Device / Area group

Monitoring signal list

Alarm history (time, severity)

Fig. 1. Sample of the CSS UI for the BEAST operated at the
RIBF control system. A green signal indicates normal
operation, whereas red-highlighted signals are currently
outputting an alarm (except for the alarm history part).

requires a restart of the EPICS IOC, which may aﬀectbeam delivery. The new system allows changing alarm
conditions during beam delivery without aﬀecting thebeam delivery.
The second is related to the NIO-C successor developed as a PLC module in 2016.5) We reported in Ref. 5)that we could successfully control 34 magnet power supplies by using the NIO-C successor in the same manneras the existing system, which uses the NIO-C developed
based on the Versa Module Eurocard (VME) bus. However, it became clear that the command processing timeof the NIO-C successor is longer with higher ﬂuctuation
than that of VME-based NIO-C. While the commandprocessing time for one NIO-S was 11.8 ms on averageand ﬂuctuated in the range of 11.7–11.9 ms in the VMEbased NIO-C system, the NIO-C successor system took
18.3 ms on average and ﬂuctuated in the range of 4–
37 ms. The speed is too slow in actual accelerator operation. After investigation, we found that the slow speed
is caused by a logic of polling performed by NIO-C, which
is one of the important functions of the NIO system. By
improving the logic, the average command processing
time was shortened to 7 ms on average, and the ﬂuctuation range was narrowed down to 2.7–12.2 ms. The next
step is to determine whether the new system shows thesame performance in an actual operating environment,
in which several NIO-Ss are connected to one NIO-C.
References

1) M. Komiyama et al., RIKEN Accel. Prog. Rep. 39, 239(2006).
2) http://controlsystemstudio.org/ .
3) https://github.com/ControlSystemStudio/cs-studio/
wiki/BEAST .
4) https://epics.anl.gov/ .
5) M. Komiyama et al., Proc. PCaPAC2018, pp. 66–68.

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RIKEN Accel. Prog. Rep. 53

Power supply backup system for injection and extraction magnets ofcyclotrons
K. Kumagai∗1 and N. Fukunishi∗1
A large number of electromagnets are used to accelerate ion beams in the RIBF1) . For example, in the case of
the uranium-beam machine time, there are 500 electromagnets from RILAC2 to the end of SRC through RRC,
fRC, and IRC, each of which is excited by a DC power
supply with high current stability. As a high-quality
beam cannot be emitted unless all power supplies areavailable, it is important to perform the regular maintenance of power supplies and to consider how to handle
them if a failure occurs. In particular, in the case ofa failure during the machine time, it is necessary to restore the power supply as quickly as possible to minimize
downtime.
If any power supply fails, we attempt to repair it ﬁrst.
However, if the defective part cannot be identiﬁed immediately, the part is estimated to take time to repair,or a replacement is not at hand, it is necessary to consider whether another power supply can be used. As
power supplies with relatively low output current, suchas those for quadrupole magnets and steering magnets,
have relatively small chassis and are easy to handle, it iseasy to replace them with the same type of power supply
used for other beam courses. Since the output currentof the power supply for the trim coil and the dipole is
not very large, about 500 A at maximum, it is possible to substitute a power supply for other courses. On
the other hand, the main coil power supply for the four
cyclotrons (RRC, fRC, IRC, and SRC) typically has an
output of several hundred to several thousand amperes
and several hundred volts, and no power supply can be
replaced. Therefore, in the event of a failure, it is necessary to repair this power supply; therefore, we prepare
as many spare parts as possible.
Each cyclotron has 4 to 5 injection magnets and 3 to
5 extraction magnets. These magnets require extremely
high current of approximately 1000 A to 3500 A andvarious voltages ranging from 20 V to 120 V. Despite thelarge number of power supplies, the power supply chassis
are large and need many thick output-current cables;
therefore, it is diﬃcult to relocate the power supply after
a failure occurs. Therefore, a plan has been considered inwhich a power supply that can be replaced in the eventof a failure is arranged at an appropriate place and used
as a replacement for as many injection/extraction power
supplies as possible by adding partial temporary wiring.
The fRC-EBM power supply, a power supply for thefRC Extraction Bending Magnet manufactured in 2012,
was designed to be operated in the dual pattern of large
current-low voltage (2800 A–65 V) and medium currentmedium voltage (1500 A–100 V) in anticipation of use
as an alternative power supply. The thyristor rectiﬁcation part of the power supply is equipped with twounits, which can be connected in parallel or series, and∗1

RIKEN Nishina Center

Fig. 1. Wiring layout of the backup power supply for the
injection/extraction magnets of RRC and IRC.

the voltage-current ratio can be changed. In addition,
the transistor driver is prepared in two patterns having
diﬀerent control constants. In 2014, we reassigned thepower supply as that for the DAKR magnet on the IRCE5 beam line, which is operated several times a year, andwired it so that it could be used as an alternative power
supply for injection and extraction magnets of the RRC
cyclotron (hereafter referred to as “backup power supply”). In 2019, the wiring was extended so that it could
be used as a substitute for the power supply for injectionand extraction magnets of the IRC cyclotron if a failure
occurs. Figure 1 shows the current wiring layout of the
backup power supply.
A malfunction of the RRC-EBM1 power supply occurred on November 13, 2019 during a preparation period for uranium machine time. It was caused by the
failure of a shunt made of zeranin, a low-resistance alloy
for high-precision current detection, immersed in cooling water and had been used since the power supply was
manufactured in 1985. It was expected that it would
take about a week to remove the failed shunt, install
the DCCT, replace the accompanying control boards,
and make overall adjustments. Therefore, we immediately decided against repairing, switched the RRCEBM1 magnet to the backup power supply, and resumed
operation on the same day.
In addition, to enable the immediate use of the alternative power supply in case of trouble, we installed AC
400 V power receiving equipment, cooling water piping
for the alternative power supply, and wiring for the DC
current output in various places. In this manner we arepreparing to maintain the machine time.
Reference

1) Y. Yano, Proc. PAC07, TUYKI02, 700 (2007).
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RIKEN Accel. Prog. Rep. 53

Improvement of beam stability by stabilizing the cooling-watertemperature for the main and trim coils of IRC
R. Koyama,∗1,∗2 T. Maie,∗1 K. Kumagai,∗1 and N. Fukunishi∗1

&&#"% -*(*$'&( The improvement of the thermal stability of IRC madethe extraction beam from IRC and the beam trajectoryin SRC stable, and thereby, a tuning procedure for the
suppression of heat load on SRC-EDC consistent withthe overall beam-transmission eﬃciency has been facilitated. Consequently, we achieved the highest intensity
thus far of 94 particle nA for 345 MeV/nucleon 238 U
which is also attributed to other continuous eﬀorts.

   #&('%#' )+ ()' #% "")+ (# $% "")+ ( +)% %'%)# $$)' #% "($"%*%)"*.
,("*"&%"$/   &') "$+)') %$ #&('%#' )+ ("$/ &') "$#*''$) $!) %$ $'!)
("*%)

# $)$( ),'%#")+ (#*''$) $!) %$ )#&
' )+ (# $)$( ),'%#")+ ($'!)
("*%)

$"%*%)"*.
,("*"&%

a) Temperature of the primary cooling water for themain and trim coils of IRC. The ﬂuctuation rangesof both were improved from ∼6◦ C to 0.2◦ C.
b) Rising temperature of SRC-EDC due to the beamloss. It was improved from 8 ± 1◦ C to 6 ± 0.5◦ C.
c) Opening of temperature-regulating valves for thesecondary cooling water of the main and trim coilsof IRC. They were ﬁxed to 50% for stabilization.
d, e) Stability of the beam intensity and phase observedby the phase probe K01 (∼5 m downstream from
IRC). The ﬂuctuation range of beam intensity isimproved from 8% to 3% and that of beam phase isimproved from 0.1 ns to 0.01 ns.

#,
&'%"% )#&
' )+ (#,
&'%"% )' #% "")+ (stabilized by ﬁxing the valve openings to 50%, and theresulting extraction beam from IRC was stabilized.
The correlation between the values before and after
improvement are shown in the left and right part of
Fig. 1, respectively, where the details are as follows (theitemization corresponds to that in Fig. 1):

")"% *$'(*+(& # $% "")+ (")"% *$'(*+(& &&#"% -*(*$'&( Thermal stability is highly important for the stable
operation of RIBF with a high-intensity beam. It makes
the beam trajectory in a cyclotron stable and thereby
reduces the heat load due to beam loss on the septumof the electrostatic deﬂection channel (EDC), especiallyof SRC. Consequently, the beam-tuning for obtaining ahigh-intensity beam is facilitated.
The periodic ﬂuctuation of the heat load on SRCEDC has been observed with high-intensity beams suchas 345 MeV/nucleon 238 U since 2017. It has been thefastest and most eﬀective method to adjust the rf voltage and/or phase of RRC and/or fRC to suppress theincrease in heat load, but such an adjustment has anegative impact on the improvement of overall beamtransmission eﬃciency.
An investigation performed at the end of 2018 clariﬁed that the period of such heat-load ﬂuctuations is
synchronized with the ﬂuctuation period of the coolingwater temperature for the main and trim coils of IRC(upstream cyclotron of SRC). This synchronization iscaused by the periodic movement of the temperatureregulating valves for the secondary cooling water of thesecoils with 0–100% opening, which results from some kindof failure of the temperature control system.
In a 2019 operation of a 345 MeV/nucleon 238 U, thetemperature of both the primary and secondary coolingwater of the main and trim coils of IRC were drastically&') "$+)') %$ '(*"#%Fig. 1. Stabilizing eﬀect of cooling-water temperature for the main and trim coils of IRC in a
345 MeV/nucleon 238 U operation. The data acquired before and after stabilization are indicatedon the left and right part, respectively.
∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

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RIKEN Accel. Prog. Rep. 53

Interlock signal application from radiation monitoring ion chamber for
SRC
M. Nakamura,∗1 K. Yamada,∗1 A. Uchiyama,∗1 H. Okuno,∗1 and M. Kase∗1
Recently, we attempted to monitor the radiation due
to beam loss in the RIBF using ionization chambers(ICs).1,2) Usually, we investigate the radiation from theelectrostatic deﬂection channels (EDC) at RRC, fRC,
IRC, and SRC.3) On the other hand, the intensities of
the ion beams generated by RIBF increase in every year.
Accordingly, the management of the beam loss at important positions in RIBF is increasingly important for safeand eﬃcient operation of RIBF. In this study, we investigated the IC signal near the EDC of SRC and attempted
to input the alarm signal from this IC to the beam interlock system (BIS) of RIBF in the user time of a 238 U86+
beam.
Usually, the alarm levels of the ICs are determinedby comparing the signals from the ICs with those fromthermocouples set at the septum of the EDC of SRC.4)
Hence, the temperatures of the ﬁrst septum were compared with the signals of the IC set near the EDC of SRC
from October 15 to December 10 in 2018. The results
are shown in Fig. 1. The data demonstrated little dispersion, and we can obtain a calibration curve (red line).
From this curve, we can recognize that the voltage of the
IC became approximately 1.1 V when the temperatureof the ﬁrst septum became 42◦ C.4)
From November 12 to December 6 in 2019, the238 86+U
ion beam was accelerated to 345 MeV/nucleon.
Before this acceleration time, we set the alarm level of
IC at 1.1 V to the BIS.
Investigations were performed during this term by inputting the alarm signal to the BIS. However, in thisTable 1. Frequencies of troubles for which the BIS was engaged during the acceleration of the 238 U86+ beam in
2019.

SRC-EDC-ARC
RF-Tr
PS-Tr
BF-Tr
Others

1080
450
375
282
1614

Total

3801

term, we could not observe signals stronger than 1.1 V,
which was the estimated alarm level. Consequently the
BIS from IC near the EDC did not act in this time.
From these results, we could consider that the operationof the SRC in this term was completed favorably.
Subsequently, we investigated the frequency at which
the BIS of all RIBF systems was engaged from October 23 to December 10 in 2018. In this term, BIS was
engaged 19049 times. This result shows that BIS was engaged about 389 times per day. On the other hand, from
November 12 to December 6 in 2019, BIS was engaged
3801 times. This result shows that BIS was engaged
about 152 times per day. By comparing these two results, we could recognize that the operations of RIBF in2019 were completed more safety and eﬃciently than in
2018.
Next, we investigated the type of alarm signals put
into BIS during the acceleration of the 238 U86+ beam in
2019. BIS engagement via arc discharge at the EDC of
SRC (SRC-EDC-ARC) was observed most frequently.
BIS engagement due to a trouble of RF (RF-Tr) had
the second-highest frequency. BIS engagement due totroubles of a power supply in RIBF (PS-Tr) and due totroubles of baﬄes (BF-Tr) were also frequently observed.
The frequencies of these troubles are listed in Table 1.
Considering these results, we will investigate the correlation of the IC voltage and the conditions under which
the arc discharge at the EDC of SRC is generated in thenext step. Subsequently, we will re-examine the alarmlevel of IC.
References

Fig. 1. Correlation between the IC voltage and the temperature of the first septum of EDC.
∗1

RIKEN Nishina Center- 96 -

1) M. Nakamura et al., RIKEN Accel. Prog. Rep. 52, 114 (2018).
2) M. Nakamura et al., RIKEN Accel. Prog. Rep. 51, 139 (2017).
3) M. Nakamura et al., RIKEN Accel. Prog. Rep. 50, 152 (2016).
4) M. Nakamura et al., RIKEN Accel. Prog. Rep. 49, 146 (2015).

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 53

Nishina RIBF water-cooling system operational report 2019
T. Maie,∗1 K. Kusaka,∗1 Y. Watanabe,∗1 E. Ikezawa,∗1 M. Oshima,∗2 H. Shiraki,∗2 H. Hirai,∗2 K. Kobayashi,∗3
and J. Shibata∗3
Operation condition
In 2019, the cooling systems of Nishina and
RIBF were operated for a slightly longer period than the accelerators.
Excluding some installation that was run continuously, RIBF’s cooling systems were operated for approximately fourmonths. Furthermore, Nishina’s cooling systems AVFstandalone, AVF+RRC, AVF+RRC+IRC, and RILAC II+RRC+GARIS-II were operated for approximately eight months.
No huge troubles that could cause the long-term interruption of accelerator operation occurred, and thecooling systems operated stably with the exception ofsome minor problems.

Photograph of the RRC Cooling capacity augment equipment

Trouble report
Many issues occurred because of the cooling systems,
and all of the inverters were unexpectedly renewed owing to these issues. There was a malfunction of the
bearing of the cooling water pump motor, an issue withthe control valve of cooling water for stable supply, anda failure of the inverter for the cooling-water pump due
to aging.

cooling capacity of RRC and for stabilizing the coolingwater temperature of RRC was safely completed in
March 2019. While the implementation of new systems has not started yet, reasonable data could be obtained during the trial operation. It is expected thata progress report concerning implementation will beavailable in the next year.

Periodic maintenance

References

1) T. Maie et al., RIKEN Accel. Prog. Rep. 51 (2017).
2) T. Maie et al., RIKEN Accel. Prog. Rep. 52 (2018).

(1) Cleaning of the cooling towers(2) Inspection and overhauling of the cooling-waterpumps(3) Inspection of the inverter for the RIBF coolingwater pumps(4) Replacement of some superannuated hoses,
joints and valves used in the system(5) Cleaning of the strainers and filters used in thedeionized water production system(6) Extension of the sensing wires of the waterleakage alarm to floors of new areas(7) Flushing work of the cooling-water pipe that was
blocked by dirt
New installations and improvememts
The cooling systems for the superconducting RILAC, which had been constructed in the previous year,
started operation for commissioning. In addition, newcooling systems, which were built for increasing the
∗1
∗2
∗3

RIKEN Nishina Center
Nippon Air Conditioning Service Co., Ltd.
SHI Accelerator Service Co., Ltd.

- 97 -

9. Instrumentation

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Development of ZeroDegree Large Acceptance Dispersive mode
H. Takeda,∗1 N. Fukuda,∗1 H. Suzuki,∗1 Y. Shimizu,∗1 D. S. Ahn,∗1 T. Komatsubara,∗1 N. Inabe,∗1 K. Yoshida,∗1
S. Chen,∗2,∗3 M. Wada,∗3 A. Takamine,∗1 P. Doornenbal,∗1 and R. Tsunoda∗4
The ZeroDegree spectrometer1) is an RI-beam delivery
line following the BigRIPS separator.2) Four operating
modes are provided: two achromatic and two dispersivemodes with diﬀerent momentum resolutions and acceptances. Among them, the Large Acceptance Achromatic(LAA) mode is the standard one, and most experiments
have been conducted in this mode so far.
A parasitic experiment is proposed using ZeroDegree,where the online commissioning of a SLOWRI gas
catcher and a multi-reﬂection time-of-ﬂight mass spectrograph (MRTOF-MS) located at the ﬁnal focal plane
F11 will be performed symbiotically with other ZeroDegree experiments. For this purpose, mono-energetic
beams are desired to improve the stopping eﬃciency because the material thickness of a gas cell is very thin.
In order to realize such beams, a straight-forward solution is to employ a mono-energetic wedge degrader at thedispersive focal plane (F9 or F10) in the standard LAA
mode. However, transmission loss due to the degrader
may be a problem. Another option is to use a dispersive mode of ZeroDegree with a mono-energetic degrader
located immediately before the gas cell to minimize thetransmission loss. Both the previously prepared dispersive modes (MRD and HRD1) ) are undesirable because
they have a smaller acceptance compared to the LAA
mode as a result of aiming at a high momentum resolution. Thus, a new dispersive mode with a larger acceptance, named the Large Acceptance Dispersive (LAD)
mode, was developed. Figure 1 shows the ﬁrst-order ion
optics in the LAD mode of ZeroDegree. The horizontal acceptance and momentum resolution p/∆p are ±35
mrad and 2100, respectively, while they are ±20 mradand 4200 for the MRD mode and ±10 mrad and 6500
for the HRD mode, respectively.
A machine study with a 80 Zn beam produced by the
in-ﬂight ﬁssion of a 238 U beam at 345 MeV/nucleon witha 4 mm-thick Be target was conducted to examine theFig. 1. First-order ion optics in the LAD mode of ZeroDegreein the horizontal (X) plane. Red, green, and blue curves
correspond to the momentum deviation δ = −1.5, 0, and
1.5%, respectively.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Department of Physics, The University of Hong Kong
KEK Wako Nuclear Science Center
Center for Nuclear Study, the University of Tokyo

Table 1. Measured (Exp.) and designed (COSY) F8-F11
first-order transfer matrix elements in the LAD mode.
The units are mm, mrad, and % in x, a, and δ, respectively.
Exp.
COSY

(x|x)
1.02
1.0

(x|a)
0.27
0.0

(a|x)
−0.35
0.0

(a|a)
0.89
1.0

(x|δ)
20.3
21.0

(a|δ)
−5.49
0.0

Fig. 2. Z versus A/Q plot measured in the ZeroDegree LAD
mode. The 80 Zn beam is clearly separated.

LAD mode. The LAA mode with a mono-energetic degrader (LAAmono mode) was also tested3) in the samemachine study. We report the results for the LAD modehere.
The RI beam was identiﬁed and tagged4) in the BigRIPS separator and delivered to the ZeroDegree spectrometer. We ﬁrst measured the transfer matrix elements in the LAD mode. The results are summarizedin Table 1 and compared with the designed values calculated by COSY INFINITY. The main features are well
reproduced.
By using these matrix elements, particle identiﬁcation
was performed independently in the ZeroDegree spectrometer. The measured Z versus A/Q particle identiﬁcation plot is shown in Fig. 2. The A/Q resolution wasmeasured at narrow (±0.1%) and wide (±3%) momentum slit settings. The results were 0.15% and 0.17%
in σ, respectively. Higher-order aberration correction
is required to reach an expected value of 0.05% estimated from detector resolutions and ion-optical parameters. Analysis is in progress.
The transmission eﬃciency was also measured by comparing the number of 80 Zn with BigRIPS and ZeroDegree. The results were 85.5% (narrow) and 70.2%(wide). The transmission losses mainly occur at F10,
where the beam spreads for a large momentum deviation (δ) (see Fig. 1). The readjustment of ion optics isnecessary to reduce the beam spread.
References

1) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 03C003 (2012).
2) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
3) S. Chen et al., in this report.
4) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).

- 99 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Large-acceptance achromatic mode with mono-energetic wedge
degrader for ZeroDegree spectrometer
S. Chen,∗1,∗2 H. Takeda,∗3 M. Wada,∗2 P. Doornenbal,∗3 D. S. Ahn,∗3 N. Fukuda,∗3 S. Iimura,∗3 H. Ishiyama,∗3
J. Liu,∗1,∗2 M. Rosenbusch,∗2 P. Schury,∗2 Y. Shimizu,∗3 H. Suzuki,∗3 A. Takamine,∗3 and K. Yoshida∗3






















Fig. 1. (a) ZeroDegree setup for the LAAmono mode. (b)Energy distributions of 80 Zn before (left) and after (right)
the F10 wedge degrader.
∗1
∗2
∗3

Department of Physics, The University of Hong Kong
KEK Wako Nuclear Science Center
RIKEN Nishina Center

LAA mode
33

33

32

102

Z

31

30

10

29

30

10

29

28
27
2.55

LAAmono mode

32

102

31

Z

An experiment was proposed to achieve the online
commissioning of the SLOWRI gas catcher and multireﬂection time-of-ﬂight (MRTOF) mass measurements
symbiotically with in-ﬂight experiments using the ZeroDegree spectrometer.1) A 50-cm-long cryogenic He gas
cell will be placed downstream of the F11 chamber toprovide low-energy radioactive isotopes from the energetic radioactive isotope (RI) beams of ZeroDegree. For
ZeroDegree, the typically used large-acceptance achromatic (LAA) mode provides beams with a large energy
spread at the F11 focal plane, resulting in a relatively
low stopping eﬃciency (∼1%) in the gas cell. In order to improve the stopping eﬃciency, mono-energetic
beams are prefered. Two ion optic settings were proposed to make such beams: the large-acceptance dispersive (LAD) mode2) and the LAA mode with a monoenergetic wedge degrader (LAAmono). The transmission eﬃciencies and particle identiﬁcation resolutions
were investigated for both modes. Herein, we report
the results of the LAAmono mode.
A test was performed with a typical experimental con-

1

2.6

2.65

A/Q

2.7

2.75

2.8

28
27
2.55

1

2.6

2.65

2.7

2.75

2.8

A/Q

Fig. 2. Particle identification plots from the LAA mode (left)and LAAmono mode (right). The 80 Zn isotopes are indicated by the red ellipse in both plots.

dition for an in-beam gamma-ray experiment. A combination of a 345 MeV/nucleon 238 U primary beam anda 4-mm-thick 9 Be target was used to produce radioactive beams around 79 Cu at ∼270 MeV/nucleon. BothBigRIPS and ZeroDegree were tuned for the 80 Zn isotopes. The LAA and LAAmono mode were applied inturns for the ZeroDegree spectrometer. In the LAAmono mode, an Al wedge degrader with an angle of
20.8 mrad and a center thickness of 2.85 mm was employed at the momentum-dispersive focal plane (F10) of
the standard LAA mode, as shown in Fig. 1(a). Theenergy distribution of 80 Zn isotopes after the wedge degrader [Fig. 1(b) right] shows a good mono-energetic
property. A stopping eﬃciency of ∼5% in the gas cell
was estimated from this distribution.
The particle identiﬁcation (PID) for both modes was
performed using the time of ﬂight from F8 to F11, reconstructed Bρ between F8 and F10, Bρ between F10
and F11, and ∆E measured using the F11 ionizationchamber. The PID plots from both modes are shownin Fig. 2. The one from the LAAmono mode exhibitsa resolution slightly worse than the one from the LAA
mode, but the resolution was suﬃcient to separate all
the diﬀerent isotopes well. The transmission eﬃciencies
of ZeroDegree were studied by comparing the statisticsof the 80 Zn isotopes in BigRIPS and ZeroDegree PID
plots. The LAAmono mode keeps 95% eﬃciency in comparison with the standard LAA mode in this test experiment. This eﬃciency is consistent with the value estimated from LISE++ calculations, which suggests thatthe main loss originates from the reaction losses in thewedge degrader.
References

1) M. Wada, RIKEN Proposal NP1912-RIBF176.
2) H. Takeda, in this report.

- 100 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

New ion-optical operating modes of BigRIPS and ZeroDegree
spectrometer for production and separation of high-quality rareisotope beams and high-resolution spectrometer experiments†
H. Takeda,∗1 Y. K. Tanaka,∗2 H. Suzuki,∗1 D. S. Ahn,∗1 B. Franczak,∗2 N. Fukuda,∗1 H. Geissel,∗2
E. Haettner,∗2 N. Inabe,∗1 K. Itahashi,∗1 T. Komatsubara,∗1 T. Kubo,∗1,∗3 K. Kusaka,∗1 S. Y. Matsumoto,∗4
D. Murai,∗1 T. Nishi,∗1 M. Ohtake,∗1 C. Scheidenberger,∗2 Y. Shimizu,∗1 T. Sumikama,∗1 H. Ueno,∗1
T. Uesaka,∗1 Y. Yanagisawa,∗1 and K. Yoshida∗1
BigRIPS1) is a powerful two-stage in-ﬂight separator
that has been used for frontier experiments with exotic
nuclei for more than a decade. The ion-optical system is very versatile owing to the multi-stage structureof BigRIPS combined with the ZeroDegree spectrometer2) or the Superconducting Ring Cyclotron (SRC).
Various optical modes can be ﬂexibly realized according to the purpose of experiments. Two categories ofdevelopments are presented here.
One is a new operating mode of BigRIPS aiming at
a higher ion-optical resolving power. BigRIPS itself
has a two-stage structure consisting of F0-F2 and F3F7 with a matching section F2-F3 in between. In eachstage, the isotopic separation of projectile fragments
at an overall achromatic focus is performed in the Bρ∆E-Bρ operation with an achromatic energy degrader
positioned in a dispersive focal plane. In principle, thetwo stages act independently and their isotopic separation powers can be added or subtracted dependingon the sign of the optical magniﬁcation in the matching section F2-F3. In the standard operating mode of
BigRIPS, the two spatial separations with energy degraders are subtractive. The ion-optical solution foradding the Bρ-∆E-Bρ separation power (the additivemode) is obtained by adding an x-focus at F2.5. The
spatial-separation performance of the standard and additive modes of BigRIPS is demonstrated in the simulation with diﬀerent combinations of achromatic F1and F5-degraders. With the resulting increased spatial
separation power, the isotopic background can be substantially reduced. On the other hand, the standard
mode has a slightly better overall transmission and issuperior in providing an isotope cocktail focused on asmall-area detector or a secondary target. One canfavorably use either the standard or the new additivemode depending on the experimental requirements andpriorities.
Higher ion-optical resolving powers of the ﬁrst andsecond BigRIPS stages are also investigated with thegoals of further reducing the background and yielding

access to new isotopes of heavier elements. First, theresolving power of the second stage was doubled (thehigh-resolution Ddouble mode3) ). Improved particle
identiﬁcation was conﬁrmed by the ﬁrst test experiments. The simulation of a test case indicated that theincreased resolving power of both the ﬁrst and second
stages in the additive mode can reduce the backgroundto a large extent. The actual use of the proposed andprepared additive, standard, and higher-resolution ionoptical modes primarily depends on the detailed goalsof future BigRIPS experiments.
The other development is a dispersion-matched system with BigRIPS for high-resolution spectrometer experiments. The BigRIPS and ZeroDegree spectrometer are presently two independent, coupled achromatic
systems. A new dispersion-matched mode of BigRIPS
and ZeroDegree will enable novel experiments. In thisexperimental scenario, the F8 focal plane is dispersive and accommodates the secondary target. The secondary target can be viewed, e.g., by the γ-ray detector
array, and thus, high-resolution momentum measurements after a removal reaction can be performed at
F11 in coincidence with γ-spectroscopy.
For high-resolution spectroscopy experiments withhigh-intensity light projectiles, SRC and BigRIPS canbe operated as a dispersion-matched system. In thismode, the dispersive beamline from SRC to F0 and the
BigRIPS stages up to F5 form an overall achromatic
system. The momentum spread of high-intensity primary beams from the SRC is canceled in the position
spectra at F5, for instance, in the experiments studying pionic states. The ﬁrst experimental tests of the
proposed ion-optical mode have been successfully performed.
The described diﬀerent ion-optical developments will
be a base for novel BigRIPS experiments with exotic
nuclei and mesic atoms, and thus, contribute to a better understanding of the strong interaction and properties of hadronic matter.
References

†
∗1
∗2
∗3
∗4

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 463, 515 (2020)
RIKEN Nishina Center
GSI Helmholzzentrum für Schwerionenforschung GmbH
Facility for Rare Isotope Beams and National Superconducting Cyclotron Laboratory, Michigan State University
Department of Physics, Kyoto University- 101 -

1) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
2) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 03C003(2012).
3) H. Suzuki et al., RIKEN Accel. Prog. Rep. 46, 155(2013).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Purification of slowed-down RI beam
T. Sumikama,∗1 D. S. Ahn,∗1 N. Fukuda,∗1 N. Inabe,∗1 T. Komatsubara,∗1 K. Kusaka,∗1 M. Ohtake,∗1
H. Sakurai,∗1 Y. Shimizu,∗1 H. Suzuki,∗1 H. Takeda,∗1 Y. Yanagisawa,∗1 K. Yoshida,∗1 M. Dozono,∗2 N. Imai,∗2
S. Michimasa,∗2 R. Tsunoda,∗1,∗2 Y. X. Watanabe,∗3 M. Hausmann,∗4 and O. Tarasov∗1,∗5(1) purification of the RI beam using the two-stage
separation,(2) two-step momentum compression, and(3) transport of three charge states coupled with
PID using a time-of-flight (TOF) measurement
after the purification.
In this report, we focus on the RI-beam purification.
An experiment to verify the HIPSER concept was
performed using a 107 Pd beam produced with the BigRIPS separator at RIKEN RIBF. The 107 Pd beams
were separated at the first stage of BigRIPS using a

6000
105

Ru
Rh
107
Pd
108
Ag
109
Cd
106

5000

counts

4000
3000
2000
1000
0
40

30

20

10

0

10

20

30

40

x at F3 (mm)Fig. 1. Horizontal-position distributions of 107 Pd and its
isotones at F3. The results of 105 Ru, 106 Rh, 107 Pd,
108
Ag, and 109 Cd are shown by the green-dashed, blackdashed, red-solid, black-solid, and green-solid lines, respectively.
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo
Wako Nuclear Science Center, KEK
FRIB, MSU
NSCL, MSU

- 102 -

700
105

Ru
Rh
107
Pd
108
Ag
109
Cd

600

106

500

countsThe purity of a slowed-down RI beam at the second stage of the BigRIPS separator1) is important forparticle identification (PID) under the condition of a
total rate of 105 pps or higher.2) High-purity sloweddown RI beams are desirable for experiments at BigRIPS and the OEDO beamline.3) A high-intensity purified slowed-down exotic RI beam (HIPSER) concept
is proposed to obtain high-intensity and high-purity
RI beams using two-stage separation with two thickwedge degraders before measurement using beamline
detectors for PID. The HISPER concept consists ofthree technical components:

400
300
200
100
0
40

30

20

10

0

x at F7 (mm)

10

20

30

40

Fig. 2. Same as Fig. 1 but for the positions at F7.

wedge degrader with a thickness of 4.5 mm at F1 andthe F2 slit with a ±5-mm setting. The thickness-torange ratio (d/R) was 0.47. The energy was slowed
down from 254 to 174 MeV/nucleon. The contaminants at F2 were isotones of 107 Pd, since the horizontal position xF2 of 107 Pd at F2 were the same as thoseof the isotones. Figure 1 shows xF3 distributions of105
Ru, 106 Rh, 107 Pd, 108 Ag, and 109 Cd beams measured at F3. The positions at F2 and F3 show the
relation, xF3 = −xF2 . The central values of the xF3
distribution for these RI beams were the same.
With a thicker wedge degrader at F5, the 107 Pd
beam could be separated from its isotones.1,2) The second wedge degrader at F5 had a thickness of 3.5 mm(d/R = 0.69). The F7 position xF7 of the 107 Pd beam
was separated from the isotones, as shown in Fig. 2.
By setting the F7 slit as −10 mm < xF7 < +5 mm, thepurity of 107 Pd was obtained as 32%. The beam energy
between F5 and F7 was 78 MeV/nucleon. The TOF
measurement for the three charge states was performedat the ZeroDegree spectrometer. The charge-state separation at the ZeroDegree spectrometer, influence of
higher-order aberration, and beam-energy broadening
due to energy-loss straggling will be investigated in a
future analysis.
References

1) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
2) T. Sumikama et al., Nucl. Instrum. Methods Phys. Res.
B 376, 180 (2016).
3) S. Michimasa et al., Prog. Theor. Exp. Phys. 2019,
043D01 (2019).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Thermal model simulation of high-power rotating target for BigRIPS
separator
K. Yoshida,∗1 Z. Korkulu,∗1 Y. Yanagisawa,∗1 and T. Kubo∗1
A realistic thermal-model simulation is particularly
important to evaluate the beam-power tolerance of thehigh-power rotating target system of BigRIPS separator,1,2) which has been successfully operating at RIBF
since 2007. The target system was designed to withstanda beam power of 82 kW, which corresponds to the goal
beam intensity of 1 particle µA (pµA) for a 238 U beam at
345 MeV/nucleon. The available beam intensity at RIBF
was 13 kW so far, less than 20% of the goal. Therefore,
thermal-model simulations were utilized to estimate thethermal behavior of the target system for high-intensity
beams from the observation at lower beam intensities.
Many eﬀorts1–5) have been devoted to the thermal
model simulations of the target systems with ﬁniteelement ANSYS code. In the simulations, the rotating target was modeled using a mass transport optionof ANSYS6) to describe the rotating motion. The model
worked ﬁne at the design stage4) but has been less usable because a recent version of ANSYS limits the use ofmass transport only for motion slower than the thermal
diﬀusion speed. Since the rotating target distributes theheat load by a fast rotating motion, the restriction prevents the simulation in the operational condition of therotating target.
A new model of the rotating target was developed to
avoid the restrictions. In the new model, the target itself
is ﬁxed, and a heat source moves along the circumferenceof the target. As shown in Fig. 1, many heat sources witha square shape of 1 mm by 1 mm were deﬁned along thecircle of the beam trajectory, and each source was excited by a heat load at a slightly diﬀerent timing along
the trajectory. Thus, the rotation of the heat source was
successfully accounted for in the transient thermal calculation of ANSYS. In order to obtain the temperature distribution of a rotating target at the steady state, we have

Fig. 2. Temperature distribution of the rotating target forirradiation with a 238 U beam at 345 MeV/nucleon, 1 pµA.

to simulate whole thermal equilibration process startingwith the room-temperature target. More than 400 rotations of a spot heat source were necessary to obtainthe saturation of the temperature. This process can beshortened by starting with the temperature distributionof a time-averaged heat source, which was calculated bysteady-state thermal calculations with a time-averaged
circular heat source. A nearly steady temperature distribution was obtained after 3–4 rotations of the spot
heat source in this case.
A simulation for the case of a 238 U beam at an energyof 345 MeV/n and 1 pµA impinging on a 2-mm-thick
Be target was performed, and the resulting temperature
distribution is shown in Fig. 2. Heat transfer coeﬃcientsof 10.5 and 3 kW/m2 K were used for thermal contacts
between the cooling water and cooling disk and between
the cooling disk and Be target, respectively. As shown in
Fig. 2, the highest temperature of 1230◦ C indicated by
the “Max” label was obtained at the beam spot. Starting at the beam spot, the high-temperature region was
spread along the beam trajectory. The calculation showsthat the Be target does not melt in the heat of the beam
since the melting point of Be is 1287◦ C. The maximum
temperature of the calculation for 238 U beam at 30 pnA
was 66◦ C, which is consistent with the measured temperature of 63.6◦ C at RIBF. Thermo-mechanical calculations are in progress to check the thermal deformation
or destruction of the target.
References

Fig. 1. Model of the rotating target. Graphs are the time
structure of heat loads applied to heat source cells.
∗1

RIKEN Nishina Center

1) A. Yoshida et al., Nucl. Instrum. Methods Phys. Res. A 521,
65 (2004).
2) A. Yoshida et al., Nucl. Instrum. Methods Phys. Res. A 590,
204 (2008).
3) A. Yoshida et al., RIKEN Accel. Prog. Rep. 35, 152 (2002).
4) A. Yoshida et al., RIKEN Accel. Prog. Rep. 37, 295 (2004).
5) Z. Korkulu et al., RIKEN Accel. Prog. Rep. 52, 132 (2019).
6) ANSYS. Inc Product Release 19.

- 103 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Incidents involving the DMT3 magnet in the beam transport line from
SRC to BigRIPS
K. Kusaka,∗1 K. Yoshida,∗1 M. Ohtake,∗1 and Y. Yanagisawa∗1
After the October 2017 incident, wherein the lower
correction coil in the DMT3 magnet in the “T-course”
beam line was damaged,1) a new lower correction coil was
fabricated at Toshiba and installed in DMT3 in March2018. In addition to repairing the correction coil, we renewed its water-cooling channels such that the coolingwater lines of correction-coil pancakes are independent
from those of the main-coil pancakes. The DMT2 magnet, which is a “2-Tesla” resistive-type dipole magnet
identical to DMT3, was also improved in the watercooling design. A 18 O beam at 230 MeV/nucleon and238
U beam at 345 MeV/nucleon were safely transported
to the BigRIPS target via the “T-course” beam line with
the DMT2 and DMT3 magnets in 2018.
When we improved the cooling-water piping, we
ﬂushed all the cooling channels in DMT2 and DMT3
coils. Every pancake of the main and the correction coils
was ﬂushed with compressed air and water. We found aconsiderable amount of black powdery impurities in thewater that rinsed all the cooling channels. The composition of the impurities was analyzed using an electronprobe micro analyzer (EPMA), and we found that the
impurity was mostly copper-oxide crystals. The amountof the impurities we extracted from the non-damaged
upper correction coil of the DMT3 magnet was 0.8 g.
We investigated the cooling-water channel in the damaged correction coil by cutting the coil conductor. We
cut the damaged coil into 11 pieces. Figure 1 shows,as an example, a cross section of the correction coil cut
at a saddle-shaped coil end. Although we found no notable evidence of blockage by impurities, it is likely thata shortage of heat removal due to poor cooling-water ﬂow
in the correction coil damaged the epoxy isolation.
A 78 Kr beam and 124 Xe beam at 345 MeV/nucleon
were transported and RI beam experiments were successfully performed in the early summer 2019. However,at the beginning of the uranium beam time in November 2019, we again faced a similar incident, wherein theupper correction coil in the DMT3 magnet was damaged. The DMT2 and DMT3 magnets were excited withcurrents of 596 A and 594 A, respectively. However,
the total excitation voltage of the DMT3 magnet wasFig. 1. Cross section of the damaged lower correction coil atthe saddle-shaped coil end.
∗1

RIKEN Nishina Center

Fig. 2. Damaged upper correction coil of the DMT3 magnet.

131.6 V, which was about 10 V lower than the voltageof the DMT2 magnet (141.2 V). Furthermore, the temperatures of the cooling-water outlet of the upper andlower correction coils of the DMT3 magnet were 20.5◦ C
and 40.1◦ C, respectively. We concluded that the uppercorrection coil in the DMT3 magnet was short-circuited.
In order to complete the beam service successfully, we
isolated the upper correction coil from the excitation circuit, as we had done in 2017. The DMT3 magnet was
re-excited while monitoring the voltage of each coil pancake.
Furthermore, we introduced an additional auxiliary
DC power supply in the DMT3 excitation circuit in aparallel connection. Water-cooled protection diodes werealso used for safety. We excited the DMT3 magnet using two power supplies with currents of 110 A and 536 A
so that the uranium beam was safely transported to the
BigRIPS target from SRC. After 2 days of beam-timesuspension, scheduled experiments were performed till
December 6. At the end of the beam time, we tested thetransportation of the uranium beam using the DMT3
magnet without correction coils. We excited only themain coils of DMT3 magnet using two power supplies
with currents of 110 A and 563 A. We conﬁrmed thatthe uranium beam focused on the BigRIPS target welland the main coils were well cooled with a suﬃcient water ﬂow.
We investigated the upper correction coil by inserting a ﬁberscope CCD camera into the space between themain coils of the DMT3 magnet after the beam time.
Damage was found at the position of the second coil support from the beam exit side. Figure 2 shows the damageon the outer circumference of the upper correction coil.
The origin of the incident is under investigation.
Reference

1) K. Kusaka et al., RIKEN Accel. Prog. Rep. 51, 173 (2018).
- 104 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

First confirmation of stopped RIs at parasitic gas cell with new
approach
T. Sonoda,∗1 I. Katayama,∗1 M. Wada,∗2 H. Iimura,∗3 V. Sonnenschein,∗4 S. Iimura,∗1 A. Takamine,∗1
M. Rosenbusch,∗2 T. M. Kojima,∗1 D. S. Ahn,∗1 N. Fukuda,∗1 T. Kubo,∗1 S. Nishimura,∗1 Y. Shimizu,∗1
T. Sumikama,∗1 H. Suzuki,∗1 H. Takeda,∗1 M. Tanigaki,∗5 H. Tomita,∗4 K. Yoshida,∗1 and H. Ishiyama∗1
We are developing a scheme of parasitic low-energy
RI-beam production (PALIS)1) in the second focal
chamber (F2) of BigRIPS to establish the eﬀective utilization of rare isotopes and to perform comprehensive
measurements of the physical properties of exotic nuclei.
From previous experimental results,2) we ﬁgured outthat very intense radiation stays around the highenergy beam passage in F2. Under an intense radiation
environment, a strong plasma can easily be created inside the PALIS gas cell, which prevents the stopped RIs
from proper extraction. Therefore, we applied a new
approach to transport the stopped RIs from the strong
plasma via a long gas tube towards a lower-radiation
environment. This concept is similar to the “heliumjet” technique, but the present approach does not use
aerosols. In this beam time, we investigated the feasibility of this new approach by using alpha emitters produced by projectile fragmentation via a uranium beamand beryllium target.
Figure 1 shows a schematic of the experimental setup.

Fig. 1. Experimental setup.

SSD1
SSD2

Fig. 2. Alpha spectra observed by SSD1 and SSD2.

The gas cell is separated into two parts: a stoppingcell and an extraction cell which are joined with a70-cm-long and thin gas tube. High-energy alphaemitter beams were introduced to the stopping cell.
The BigRIPS optical parameters were set to those in
Sumikama et al.’s experiment.3) Firstly, we conﬁrmed
alpha rays created via decays from the alpha emittersthat were stopped in the delta-E SSD by adjusting theenergy degrader. By decreasing the degrader thickness,those observed alpha emitters were stopped inside thegas cell ﬁlled with argon gas at 0.5 to 1 atm. The alphaemitters stopped in the stopping cell were transported
to the extraction cell by a gas jet, where the radiation
intensity is at least 100 times lower than in the stopping cell. We observed a part of the alpha emittersthat were accidentally incident on the silicon pin-diode(SSD1) surface facing the ﬂow path at the entrance ofthe gas tube. Finally, we could conﬁrm the alpha emitters by inserting another silicon pin-diode (SSD2) in theﬂow path at the end of the gas tube. Figure 2 shows
the alpha spectra observed at SSD1 and SSD2.
The feasibility of the new gas cell structure was veriﬁed for the ﬁrst time. In the next beam time, we will
evaluate the extraction eﬃciency and apply laser ionization for those alpha emitters.
References

∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
High Energy Accelerator Research Organization, KEK
Japan Atomic Energy Agency, JAEA
Faculty of Engineering, Nagoya University, Nagoya
Institute for Integrated Radiation and Nuclear Science,
KURNS

1) T. Sonoda et al., Prog. Theor. Exp. Phys. 2019, 113D02(2019).
2) T. Sonoda et al., RIKEN Accel. Prog. Rep. 51, 171 (2017).
3) T. Sumikama et al., Nucl. Instrum. Methods Phys. Res.
B 463, 237 (2020).

- 105 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Stopping examination for high-energy RI beams in the parasitic gas cell†T. Sonoda,∗1 I. Katayama,∗1 M. Wada,∗2 H. Iimura,∗3 V. Sonnenschein,∗4 S. Iimura,∗1 A. Takamine,∗1
M. Rosenbusch,∗2 T. M. Kojima,∗1 D. S. Ahn,∗1 N. Fukuda,∗1 T. Kubo,∗1 S. Nishimura,∗1 Y. Shimizu,∗1
H. Suzuki,∗1 H. Takeda,∗1 M. Tanigaki,∗5 H. Tomita,∗4 K. Yoshida,∗1 and H. Ishiyama∗1Fig. 1. Experimental setup.
†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Prog. Theor. Exp. Phys. 2019,
113D02 (2019)
RIKEN Nishina Center
IPNS, High Energy Accelerator Research Organization
Applied Nuclear Physics Laboratory, Japan Atomic Energy
AgencyFaculty of Engineering, Nagoya University, Nagoya
Institute for Integrated Radiation and Nuclear Sciencedegrader thickness (mm)
12.77
13.14

12.48

1
transmitted/stopped fraction

We are developing a scheme of parasitic low-energy
RI-beam production (PALIS)1) to establish the eﬀective
utilization of rare isotopes and to perform comprehensive measurements of physical properties of exotic nuclei.
So far, we spent totally about two days of on-line commissioning beam time from 2015,2,3) thanks to the RIBF
MT committee. However, as the beam time is insuﬃcient to optimize the new device, we requested the PAC
committee for authentic beam time in 2017, and 3 daysof beam time was approved. Our plan in this formallyprovided beam time consists of 3 stages: 1) stopping examination for high-energy RI beams in the parasitic gas
cell, 2) an extraction test for stopped RIs and eﬃciency
evaluation, and 3) the demonstration of physical spectroscopy using a low-energy RI beam. Here we report
the results of the 12 h of on-line experiment in the ﬁrst
stage.
A schematic of the experimental setup is shown in
Fig. 1.
Two silicon surface barrier Detectors (SSDs) were installed inside the BigRIPS F2-chamber and used for examining the ∆E-E relation. The ﬁrst detector (∆E-SSD)
was mounted immediately after the (glass) energy degrader, and the second (E-SSD) was mounted inside thegas cell. A radioactive 67 Se beam was introduced to thissetup as the main secondary beam, which was produced
by projectile fragmentation via 78 Kr (340 MeV/nucleon)
and a beryllium target. We conﬁrmed that each isotonebeam with the same neutron number (N ) = 31, 32, and33 was well separated energetically after the energy degrader. Here, the N = 33 isotone-beam, consisting of
67
Se, 66 As, 65 Ge, and 64 Ga, was adjusted to maximize

13.59

transmitted fraction
at 440 mbar
(calculation)

0.8
exp. data (440mbar)
exp. data (no-gas)

0.6
0.4

stopped fraction
at 440mbar(exp.data)

stopped fraction
at 440mbar(calculation)

0.2
0
16

18

20
22
24
26
28
degrader angle (degrees)

30

Fig. 2. Normalized transmitted and estimated stopped fractions as functions of the degrader angle.

the stopping eﬃciency in the gas. The eﬀective thicknessof the energy degrader was varied by adjusting its rotation using a stepping motor. Energy-loss spectra wereobtained with ∆E-SSD and E-SSD as the angle of theglass degrader was varied from 18 to 28 degrees.
The normalized transmitted fraction at E-SSD and
expected stopped fractions in the gas cell are plotted inFig. 2 as functions of the degrader angle for the casesof no-gas (green rhombuses) and 440 mbar argon (redcircles) in the gas cell. The experimental data at 440
mbar were well reproduced by LISE++ calculations. In
addition, the expected stopped fraction in the gas wasestimated by comparing the transmitted fractions withand without gas. In this experiment, we conﬁrmed thatapproximately 30% of the ensemble of N = 33 isotonebeams were stopped in 440 mbar argon at the optimum
degrader angle.
As a next step, we will establish the extraction technique of stopped RIs for low-energy RI-beams.
References

1) T. Sonoda et al., Prog. Theor. Exp. Phys. 2019, 113D02(2019).
2) T. Sonoda et al., RIKEN Accel. Prog. Rep. 49, 16 (2015).
3) T. Sonoda et al., RIKEN Accel. Prog. Rep. 51, 169 (2017).

- 106 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Second report on oﬄine tests for RF carpet transportation in RF ion
guide gas cell at the SLOWRI facility
S. Iimura,∗1,∗2,∗3 A. Takamine,∗1 M. Rosenbusch,∗3 M. Wada,∗3 S. Chen,∗4 J. Liu,∗4 P. Schury,∗3 T. Sonoda,∗1
T. M. Kojima,∗1 Y. X. Watanabe,∗3 A. Odahara,∗2 and H. Ishiyama∗1

Transport Efficiency to 2nd RFCP100%

He: 133 mbar
He: 200 mbar
He: 267 mbar

80%
60%
40%
20%
0%

0

50
100
150
RF Voltage on the 1st RFCP [Vpp]200

Fig. 1. 1st RFCP transportation test results in three diﬀerent helium gas pressures: 133 mbar, 200 mbar, and 267
mbar. In this test, the drag dc ﬁeld on the 1st RFCP, theextraction DC ﬁeld between the 1st and 2nd RFCPs, andeach RF frequency were 4 V/cm, 20 V/cm, and ∼5 MHz,
respectively.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Department of Physics, Osaka University
Wako Nuclear Science Center (WNSC), IPNS, KEK
Department of Physics, The University of Hong Kong

100%
Transport Efficiency to 2nd RFCP

We are developing a radio frequency carpet (RFCP)-type ion guide1) gas catcher cell (RFGC) at the
SLOWRI facility. In the previous version,2) we could
achieve a transport eﬃciency of ∼60% only in 133 mbar
helium gas on the ﬁrst carpet from oﬄine measurements.
In these developments, to improve the transport eﬃciency, we changed the carpet pitch (the distance between the center of neighboring RF electrodes) from
0.32 mm to 0.25 mm.
In our oﬄine measurements, we evaluated the transport eﬃciency of the RFGC using a surface ionization Cs
ion source placed at the inner wall of the gas cell. Firstly,
we measured the ion reaching onto the 1st RFCP by using it as a Faraday cup. Subsequently, we used the 2nd
RFCP as a Faraday cup to measure ions transported by
the 1st RFCP after applying appropriate RF and DC
ﬁelds. The eﬃciency was deﬁned by the current measured at the 2nd RFCP divided by that measured at the
1st RFCP.
Figure 1 shows the result of the obtained transport
eﬃciency as a function of the RF voltages applied to
the 1st RFCP in three diﬀerent helium gas pressures.
The transport eﬃciency reached ∼80% at each pressure,which is ∼1.3 times greater than in the previous measurements.2)
In an online experiment, the total extraction eﬃciency
is determined by the product of stopping, ion survival,

He: 133 mbar
Ne: 133 mbar
Ne: 55 mbar
Ar: 31 mbar

80%
60%
40%
20%
0%

0

50
100
150
RF Voltage on the 1st RFCP [Vpp]200

Fig. 2. 1st RFCP transportation test results for three kindsof gases: helium, neon, and argon. The DC ﬁelds condition and RF frequency were the same as in the previous
tests.

and transport eﬃciencies. In order to enable more efﬁcient stopping, heavier species of buﬀer gas have been
investigated. Figure 2 shows the result of the measured
transport eﬃciency for three kinds of buﬀer gases. The
gas pressures of neon (55 mbar) and argon (31 mbar)
were adjusted so that the beam would be stopped withthe same eﬃciency as that achieved for 133 mbar of helium. It was found that helium (133 mbar) and neon
(55 mbar) gases gave comparable transport eﬃciencies.
On the other hand, with a higher pressure for neon, i.e.,equal to the helium pressure, the transport in neon gas
was observed to be four times less eﬃcient. In addition
to these results, considering that the ion survival probability in helium is 1.3 times higher than that in neon,as shown previously,3) the total eﬃciency in helium gas
may be the best performance.
We will keep testing the RFCP to search for the optimum conditions, especially for the parameters of the 2nd
RFCP. Furthermore, the ion-guide system to be placed
behind the 2nd RFCP is under assembly; it consistsof a quadrupole ion beam guide and an ion trapping
system. After that, we can provide a low-energy RI
beam to a multi-reﬂection time-of-ﬂight mass spectrograph (MRTOF-MS), which is under preparation. We
plan to start online commissioning of the RFGC and the
MRTOF-MS in spring FY2020 at the downstream of the
ZeroDegree Spectrometer.
References

1) M. Wada et al., Nucl. Instrum. Methods Phys. Res. B
204, 570 (2003).
2) A. Takamine et al., RIKEN Accel. Prog. Rep. 52, 139 (2019).
3) P. Dendooven et al., Nucl. Instrum. Methods Phys. Res.
A 558, 580 (2006).

- 107 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

The 3rd report on oﬄine test for RF carpet transportation in RF ion
guide gas cell at the SLOWRI facility
A. Takamine,∗1 S. Iimura,∗1 M. Rosenbusch,∗2 M. Wada,∗2 S. Chen,∗3 J. Liu,∗3 P. Schury,∗2 T. Sonoda,∗1
T. M. Kojima,∗1 I. Katayama,∗1 Y. X. Watanabe,∗2 H. Ueno,∗1 and H. Ishiyama∗1

∗1
∗2
∗3

RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), IPNS, KEK
Department of Physics, The University of Hong Kong

Cs 8.34 MHZ
Cs 5.75 MHz
Cs 4.80 MHz
Cs 2.79 MHz
Cs 1.75 MHz(a)
Transport efficiency on 1st RFCP

1.2
1
0.8
0.6
0.4
0.2
0

(b)
Transport efficiency on 1st RFCP

A gas catcher cell using a radio-frequency (RF) ion
guide method1) is being developed to provide ultra-slow
RI beams at the SLOWRI facility. We built a gutterstructure ion guide gas cell, which consists of two-stage
RF carpets (RFCPs).2) We previously used strip electrodes with a pitch of 0.32 mm (electrode width of
0.16 mm and spacing of 0.16 mm) for the 1st RFCP. The
transport eﬃciency was limited to ≈60% in 133 mbar of
He gas and even lower in a higher pressure gas. We
replaced the 1st RFCP with a ﬁner pitch of 0.25 mm(electrode width of 0.1 mm and spacing of 0.15 mm)
to improve the performance. However, ﬁner-pitch RF
electrodes have a larger capacitance, which would practically limit the RF resonance frequency for the RFCP.
Therefore, we conducted an oﬄine test to investigate the
RF transport performance on the new 1st RFCP at different RFs by changing the resonance coil of the resonant
circuit.
The oﬄine test was performed using surface-ionization
ion sources of Cs and K which were placed at the innerwall of the gas cell. The setup is shown in a ﬁgure in
Ref. 2). The ions produced from the ion sources were collected onto the 1st RFCP, transported on the 1st RFCP,
and collected onto the 2nd RFCP. We measured the ion
currents, I1 , on the 1st RFCP and those on the 2nd
RFCP, I2 , by a pA meter using each of the RFCPs as a
Faraday cup. The transported eﬃciency was deﬁned as
I2 /I1 . It should be noted that for the measurements of
I1 , the DC potential distribution was slightly diﬀerent
from that in the case of I2 because we could apply a DC
gradient on the on the 1st RFCP only for the measurements of I2 .
Figure 1 shows the test results in 133 mbar of Hegas for (a) Cs+ ions and (b) K+ ions at diﬀerent RF
frequencies. The drag DC ﬁeld on the 1st RFCP was
4 V/cm, and the extraction DC ﬁeld on 2nd RFCP was
20 V/cm. We achieved a higher transport eﬃciency compared with the previous RFCP,2) although we found thatit requires a correction to the eﬃciencies by a factor of
not more than ∼0.9, which results from the DC-ﬁeld
distribution diﬀerence mentioned above. The results indicate that an RF frequency of ∼6 MHz was suﬃcientfor Cs+ (m/q = 133), although it did not saturate theK+ (m/q = 39) transport eﬃciency. According to theresults, we will operate the RF ion guide gas cell at 7–
8 MHz in the commissioning at the end of the ZeroDegree beam line in spring FY2020.
The plots clearly show that higher RF voltages are required to transport the lighter ions at a similar RF fre-

0

50
100
150
RF voltages on 1st RFCP [Vpp]

1.2

200

K 8.05 MHz
K 5.75 MHz
K 3.49 MHz

1
0.8
0.6
0.4
0.2
0

0

50
100
150
RF voltages on 1st RFCP [Vpp]200

Fig. 1. RF voltage dependence of the RF transportation efficiencies for (a) Cs+ and (b) K+ .

quency, which can be straightforwardly interpreted fromthe expression of the RF repelling force.1) The plot (a)also shows that there exist RF voltages maximizing thetransport eﬃciency for each RF frequency. We observedsome discharge-like ion currents at a higher voltage thanthe eﬃciency peak points; consequently, the discharge
seemingly disturbed the ion transport. However thetransport eﬃciency would be diﬀerent depending on theposition in an RFCP stability diagram,3) deﬁned by the
RF and DC voltage values, which has a possibility to
explain this result. An attempt at quantitative interpretation is underway.
References

1) M. Wada et al., Nucl. Instrum. Methods Phys. Res. B
204, 570 (2003).
2) A. Takamine et al., RIKEN Accel. Prog. Rep. 52, 139 (2019).
3) S. Schwarz, Int. J. Mass Spectrom. 299, 71 (2011).

- 108 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Battery-operated compact ion source for beam transport test
T. M. Kojima,∗1 T. Sonoda,∗1 I. Katayama,∗1 M. Wada,∗2 and H. Ishiyama∗1
An ion source for a beam transport test at the
SLOWRI beamline1) has been desgined and assembled.
The beamline was constructed to transport slow rareisotope (RI) ions extracted with an accelerating voltage
of a few tens of kilovolts from the PALIS apparatus2)or RF gas cell.3) PALIS and the gas cell are systems
used for catching, thermalizing, and accumulating RIs
produced at BigRIPS. At present, neither PALIS nor
the gas cell is completed, and no ion can be extracted.
Instead of those systems, an ion source is necessary to
examine ion transport at the SLOWRI beamline. However, there is no room for installing a usual ion sourceat the upstream end of the beamline, since PALIS has
been already installed at that place, i.e., the F2 chamber of the BigRIPS facility.
The newly designed ion source is used as a sideinserted-type device. It can be installed at any of theparticular CF114 ﬂanges for the beam-proﬁle monitor
on the duct (see Fig. 1). The system consists of an ion
emitter part and extraction part. The former is biased
at an accelerating voltage of a few tens of kilovolts sothat it is isolated with a CF70 isolating nipple. A comercial thermal-ionization-type alkali ion emitter (HeatWave Labs, Model 101139 Cs+ )4) surrounded with a
50 mmϕ repeller electrode is mounted at the end of theisolated rod (see Fig. 2). The emitter, which contains aheater inside, has a cylindrical shape of 6.35 mmϕ and9.9-mm length, and its end side is coated with alkali
compounds. Note that the center hole of the repeller
is 10 mmϕ, which is slightly larger than the emitter, toavoid thermal contact. The position of the emitter isdesigned to be on the axis of the beamline duct. The
heater power of the emitter is supplied by a lithium-ion

Fig. 2. Photograph of the electrode arrangement of the ion
source. The coated alkali compounds of the ion emitterare seen at the center of the repeller.

battery (GlobalTech, GANGAN GT5)5) with an output
regulating circuit. The battery and circuit are housedin an acrylic box mounted on the top of the isolating
nipple; thus, they are isolated from the GND potential.
Therefore, it is easy to apply a high voltage bias to theion emitter part. The battery, when fully charged, canoperate the ion source for more than ten hours underusual conditions. The extraction part is assembled on
the CF114 ﬂange at the GND potential. It has two electrodes, i.e., an extractor with a 6 mmϕ aperture anda “collimator” with a replacable aperture plate. One
can adjust the emittance of extracted ions by changng
the aperture size of the “collimator,” though the extracted intensity decreases as the emittance decreases.
A 4 mmϕ aperture is set currently.
The ion source was tested at a very short (40 cm)
region of the beamline, which includes only one 20-cmlong electrostatic quadrupole between the ion source
and a Faraday cup. With 10-kV acceleration and 6.8W heater power, the ion current extracted through the
4 mmϕ “collimator” was about 1 nA on the Faraday cup
at 40 cm downstream when the electrostatic quadrupole
was optimized. The intensity is suﬃcient for our purpose. In addition, a higher intensity is expected witha higher power since the rated power of the heater is11.3 W.
With this ion source, the ion-transport properties ofthe beamline will be examined and adjusted.
References

Fig. 1. Left: The assembled ion source without the heater
controller. Right: The heater controller set on the topof the CF70 isolating nipple.
∗1∗2

RIKEN Nishina Center
KEK Wako Nuclear Science Center

1) M. Wada et al., RIKEN Accel. Prog. Rep. 47, 203 (2014).
2) T. Sonoda et al., Prog. Theor. Exp. Phys. 2019, 113D02(2019).
3) M. Wada et al., Nucl. Instrum. Methods Phys. Res. B
204, 570–581 (2003).
4) https://www.cathode.com/i_alkali.htm .
5) https://g-tech.jp/gt5 . (in Japanese)- 109 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Present status of ERIS at the SCRIT electron scattering facility
T. Ohnishi,∗1 S. Ichikawa,∗1 A. Enokizono,∗1 K. Kurita,∗2 S. Sato,∗1,∗2 M. Watanabe,∗1 and M. Wakasugi∗1,∗3
The electron-beam-driven RI separator for SCRIT(ERIS)1) at the SCRIT electron scattering facility2)
is an online isotope separator system used to produce low-energy RI beams using the photoﬁssion of
uranium. Recently, we developed ion-stacking andpulse-extraction systems to improve the DC-to-pulse
conversion eﬃciency using an RFQ cooler buncher
named the fringing-RF-ﬁeld activated DC-to-pulse converter (FRAC).3) With a surface-ionization ion source,
a high conversion eﬃciency was obtained.4) In thepresent year, we produced RI beams using the surfaceionization ion source and applied the ion-stacking andpulse-extraction systems to RI beams. In this paper,
we report the results.
Details of the RI production method and the surfaceionization ion source of ERIS are reported in Refs. 4–5).
In this measurement, 43 uranium-carbide disks, with athickness of 0.8 mm and a diameter of 18 mm, were usedas production targets. The total amount of uranium
was about 30 g. The uranium-carbide disks were irradiated with an electron beam accelerated to 150 MeV.
The electron beam power was adjusted to approximately 0.25–1 W to reduce background events. The target and ionization chamber were heated to 1500–2000◦ C
by using registive heating. The electric currents applied
to the ionization chamber and target heater were 120 A
and 900 A, respectively. Ionized RIs were extracted by
the exit grid of the ionization chamber, accelerated to
10 keV, and transported to the PID system1) located at
the exit of FRAC. Particle identiﬁcation was performedby measuring speciﬁc γ rays corresponding to the decayof the RIs by using a Ge detector.
Each measurement was performed as follows. First,
we irradiated production targets for 4 min to achieve
the equilibrium state of the RI production. Next, RI
beams were injected to the PID system for 1 min while
continuing the target irradiation. Finally, the target
irradiation was stopped, and γ rays were measured for
1 min. The rate of RI production is estimated fromthe observed γ-ray yield using the eﬃciency of the Ge
detector and the half-life of the RI. For example, therate of 140 Cs production is estimated as 4×105 atoms/s
with an electron beam power of 1 W. The transmission
eﬃciency from the ion source to the PID system wasmeasured as 23% using a stable Cs ion beam. This low
eﬃciency was due to the insuﬃcient adjustment of theion-beam optics for the injection to FRAC.
The ion stacking and pulse extraction were examined using the 140 Cs beam. The stacking and extrac∗1∗2∗3

RIKEN Nishina Center
Department of Physics, Rikkyo University
ICR, Kyoto University

Fig. 1. (a) Pulse shape of the 140 Cs beam with a 100ms stacking time and 1-W electron beam power. (b)Stacking-time dependence of the stacking ratio.

tion voltages of the exit grid were 100 and −200 V, respectively. The pulse shape of the pulsed RI beam wasmeasured with a ﬁxed time window, 10 µs, by changing the time interval between the extraction from ERIS
and the injection to FRAC. Fig.ure 1(a) shows the timeinterval dependence of the measured yield of 140 Cs witha 100-ms stacking time and 1-W electron beam power.
RI beams were extracted within 20 µs, which helps realize zero escape of stacked ions from FRAC during theinjection. The stacking-time dependence of the stacking ratio is shown in Fig. 2(b). Here, the stacking ratiois the ratio of the total number of RIs measured withstacking inside the ion source to that measured without stacking. A stacking ratio of almost 0.9 was obtained at a stacking time of 100 ms, which corresponds
to the cooling time inside FRAC with a relatively small
amount of buﬀer gas (∼10−3 Pa).
Considering these results, ERIS is almost ready forthe ﬁrst electron scattering experiment with unstable
nuclei. We consider 137 Cs as a candidate isotope due
to its high production rate. Under the condition of
100% transmission eﬃciency and a 10-W electron beam
power, which is the present maximum beam power, therate of 137 Cs is expected to be 4 × 107 atoms/s, which
is suﬃcient for the experiment.
References

1) T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B
317, 357 (2013).
2) M. Wakasugi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 668 (2013).
3) M. Wakasugi et al., Rev. Sci. Instrum. 89, 095107 (2018).
4) T. Ohnishi et al., RIKEN Accel. Prog. Rep. 52, 142 (2019).
5) T. Ohnishi et al., RIKEN Accel. Prog. Rep. 48, 229 (2015).

- 110 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Latest performance of FRAC at SCRIT facility
S. Sato,∗1,∗2 A. Enokizono,∗2 T. Ohnishi,∗2 K. Kurita,∗1 M. Wakasugi,∗2,∗3 and M. Watanabe∗2
The construction of the SCRIT electron scattering facility,1) which aims to realize the world’s ﬁrst electron
scattering experiment for unstable nuclei, enabled measurement with ∼108 ions/s. In order to perform electron
scattering with unstable nuclei at a small production
rate, it is necessary to convert the ions generated continuously by the ISOL-type ion separator, Electron-beamdriven RI separator for SCRIT(ERIS),2) to a pulsed
beam with an eﬃciency as high as possible. For this purpose, we developed a dc-to-pulse converter, Fringing-Rfﬁeld-Activated dc-to-pulse Converter(FRAC).3) In 2018,
the dc-to-pulse conversion eﬃciency was greatly improved through a modiﬁcation to incorporate coolingand the 2 step-bunching method.4) In this article, wereport the optimization of the 2 step-bunching method,
the latest performance, and the future plan.
In the 2 step-bunching method, pre-pulsed beams extracted from ERIS are stacked in FRAC and extracted
as a high-intensity pulsed beam from FRAC. Therefore, to achieve a high dc-to-pulse conversion eﬃciency,
the eﬃciencies of both ERIS and FRAC are important. The most important factor in these eﬃciencies
is the extraction frequency of the pre-pulsed beam, fpre .
To determine the most appropriate fpre , we performed
two measurements. The ﬁrst measurement was of thestacking-time dependence of the stacking eﬃciency of
ERIS, EERIS . EERIS was ∼100% for stacking times up to
100 ms. The details are reported in Ref. 5). The second
measurement is of the cooling time. The cooling timeis the time until the ions injected into FRAC are suﬃciently cooled. When 133 Cs was used as the ion beamand Xe gas of ∼10−3 Pa was used as the coolant, theFig. 2. RF-amplitude dependence of the number of stackedions.

cooling time was 50 ms. From these results, the appropriate time interval for extracting the pre-pulsed beam
was determined to be from 50 ms to 100 ms. Therefore,
2 step-bunching was performed at fpre = 10 Hz.
In the measurement after the optimization of 2 stepbunching, the stacking time dependence of the eﬃciency
of FRAC, EFRAC , was measured. The measurement was
performed twice while changing the number of injectedions per second, Ninj . Figure 1 shows the results. EFRAC
was constant at ∼90% when the number of injected ions
was less than 5.2 × 107 . However, EFRAC decreased as
the number of injected ions increased further. This isconsidered to be due to the shallowing of the pseudopotential created by the RF electric ﬁeld, which is a
result of the space charge eﬀect of the stacked ions. The
ions injected thereafter cannot be stacked further.
The pseudo potential can be deepened by increasing
the RF amplitude. We measured the RF-amplitude dependence of the number of stacked ions in order to explore the possibility of improving EFRAC by increasing
the RF amplitude. Figure 2 shows the result. As theRF amplitude increases, the number of stacked ions increases and EFRAC approaches 100%. From this result,
it is concluded that increasing the RF amplitude was
eﬀective. In order to stack ∼108 ions with a higher eﬃciency, we are planning to increase the RF amplitude.
References

Fig. 1. Stacking-time dependence of EFRAC .
∗1
∗2
∗3

Department of Physics, Rikkyo University
RIKEN Nishina Center
Institute for Chemical Research, Kyoto University

1) M. Wakasugi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 668 (2013).
2) T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B
317, 357 (2013).
3) M. Wakasugi et al., Rev. Sci. Instrum. 89, 095107 (2018).
4) S. Sato et al., RIKEN Accel. Prog. Rep. 52, 144 (2019).
5) T. Ohnishi et al., in this report.

- 111 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

3D magnetic field measurement of the SCRIT electron spectrometer

0.8
0.6
0.4
0.2

(a)

Bz [ T ]By [ T ]Window-frame Spectrometer for Electron Scattering (WiSES)1) is an electron spectrometer for SelfConﬁning Radioactive-isotope Ion Target (SCRIT)2) experiment. WiSES consists of a dipole magnet,3) two drift
chambers at the entrance and exit of the magnet, a helium bag installed between the two drift chambers to reduce the multiple scattering eﬀect, and two scintillation
counters used for trigger generation. The solid angle ofthe spectrometer is about 80 msr, covering a wide rangeof scattering angles, i.e., from 30◦ to 60◦ . A typicalmomentum resolution of ∆p/p ∼ 10−3 for an electronenergy in the range of 150–300 MeV is required to separate elastic and inelastic scattering with WiSES. It was
found that the momentum resolution evaluated in pastelastic scattering experiments did not reach the design
value. One possible cause was that the map calculatedusing OPERA3D to reconstruct the trajectories of thescattered electrons had not accurately reproduced the
WiSES magnetic ﬁeld.
The scattered electrons passing through WiSES experience strong vertical focusing due to Bz , which is ahorizontal component of the fringing ﬁeld.
In order to check the calculated map, we measured
the 3D magnetic ﬁeld of WiSES with the measured accuracy ∆B/B ∼ 10−3 . The magnetic ﬁeld strength was
0.4–0.8 T, which corresponds to an electron beam energy of 150–300 MeV in the experiment. In 2018, wedeveloped a triaxial probe made from three Hall probes
to measure three ﬁeld components simultaneously.4) The
measurement resolution of these probes is about 10−6 T.
In addition, we developed a 3D driving device consistingmeasured map
calculated map
difference × 50

field
clamp

0
0.2 magnet pole
0 200 400 600 8001000
Z [mm](b)0
measured map

0.2
0.4

calculated map
difference × 50

field
clamp

magnet pole

0 200 400 600 8001000
Z [mm]

Fig. 1. Comparison between the measured map and the caluculated one near the magnetic pole. The strength of themagnetic ﬁeld was 0.8 T. (a) shows vertical component
By and (b) shows horizontal component of the fringing
ﬁeld Bz . The red line is the measured map, blue lineis the calculated one, and green line shows 50 times thediﬀerence between the two maps.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
ELPH, Tohoku University
Department of Physics, Rikkyo University
Institute for Chemical Research, Kyoto University

δp/p[×10-3]

H. Wauke,∗1,∗2 T. Aoyagi,∗1,∗2 A. Enokizono,∗1 Y. Honda,∗1,∗2 K. Kurita,∗1,∗3 S. Sato,∗1,∗3 T. Suda,∗1,∗2
S. Takagi,∗1,∗4 S. Takayama,∗1,∗2 D. Taki,∗1,∗2 T. Tamae,∗2 K. Tsukada,∗1,∗2 T. Ohnishi,∗1 M. Wakasugi,∗1,∗4
and M. Watanabe∗1

5
4

150 MeV

200 MeV

150 MeV(sim)
150 MeV(this work)

200 MeV(sim)
200 MeV(this work)

300 MeV
300 MeV(sim)
300 MeV(this work)

3
2
-5

0

5 φ [deg]

Fig. 2. Comparison of the momentum resolution between themeasured map and the calculated one. The solid lines
show the simulation results, the open circles show theresults obtained with the calculation map, and the ﬁlled
circles show the results obtained with the measured map.
Red indicates the results with 150 MeV, green indicatesthe results with 200 MeV, and blue indicates the resultswith 300 MeV.

of three electric sliders that move in a large measurement area. The 3D driving device was controlled by a
LabVIEW program. The program also read the ﬁeld
values from the Hall probes and the absolute magnetic
ﬁeld of the WiSES magnet from nuclear magnetic resonance (NMR).
Figure 1 shows the vertical component By and thehorizontal component of the fringing ﬁeld Bz of the measured map and the calculated one. The structure of themeasured magnetic ﬁeld is similar to the calculated oneeven at about 1 cm from the magnet pole. Over the entire measurement area, the diﬀerence between the twomaps was ∼10−3 T for both By and Bz . Similar results
were obtained for other magnetic ﬁeld strengths.
In November 2019, an electron scattering experimentusing a carbon target was conducted.5) The momentum
resolution is the width of the elastic scattering peak obtained in the experiment. The resolution was obtainedusing the above two maps and compared. Figure 2 shows
the result. ϕ is the azimuth angle of the scattered electrons as viewed from the target. The width of the elastic
scattering peak obtained in the experiment was used as
the momentum resolution. At three electron energies,
the momentum resolutions obtained from the measured
map in this study were almost the same as that obtained
from the calculated one.
We need further consideration to explain the diﬀerence of the WiSES momentum resolution between thesimulated and experimental values.
References

1) T. Adachi et al., RIKEN Accel. Prog. Rep. 45, 144 (2012).
2) M. Wakasugi et al., Phys. Rev. Lett. 100, 164801 (2008).
3) T. Suda et al., RIKEN Accel. Prog. Rep. 46, 184 (2013).
4) H. Wauke et al., RIKEN Accel. Prog. Rep. 52, 144 (2018).
5) K. Tsukada et al., in this report.

- 112 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Measurement of the luminosity of electron scaterring at SCRIT
D. Taki,∗1,∗2 A. Enokizono,∗1 K. Kurita,∗1,∗3 T. Ohnishi,∗1 S. Sato,∗1,∗3 T. Suda,∗1,∗2 S. Takagi,∗1,∗4
S. Takayama,∗1,∗2 T. Tamae,∗1 K. Tsukada,∗1,∗2 M. Wakasugi,∗1,∗4 M. Watanabe,∗1 and H. Wauke∗1,∗2
At the Self-Confining Radioactive-isotope Ion Target(SCRIT) electron scattering facility, we will measure
the absolute luminosity value with a luminosity monitor (LMon),1) which consists of a CsI calorimeter arrayand two-dimensional fiber scintillators. Luminosity isexpressed as follows:
L=

NBrems. 1· [cm−2 s−1 ],σBrems. ε(1)where NBrems. is the number of measured bremsstrahlung
photons per second, σBrems. is the calculated
bremsstrahlung cross section, and ε is transmittance efficiency estimated as the number of detected photons
divided by the number of photons generated from theelectron target scatterings. Because LMon is located 7 m
downstream of the vertex position and there are someobstacles in between such as cryopanels and pipes, ε isas small as 0.30–0.55 depending on the electron beamenergy, angle, width, and so on.2) Therefore, it is important to evaluate the beam condition and corresponding
ε precisely by using a detector simulation to obtain L
accurately. In a previous study,3) ε was derived by comparing the spatial distribution measured using the fiber
scintillators with the simulated one. However, it was
found that the fiber scintillators with a spatial resolution of 3 mm are inadequate to determine the beam conditions correctly. Therefore, the spatial distribution ismeasured with higher resolution by using a silicon strip
detector (SSD) in this study.
Figure 1 shows the layout of the new LMon. The
SSD has four layers (X,Y,X,Y) of silicon sensors, eachof which has a sensitive area of 7.7 × 7.7 cm2 and 1536
strips with a pitch of 50 µm pitch. We use two out of
the four layers of SSD to measure horizontal and vertical
distributions. In addition, two plastic scintillatiors areused: one is used as a trigger counter, and the other isFig. 1. Layout of the new LMon.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
ELPH, Tohoku University
Department of Physics, Rikkyo University
Institute for Chemical Research, Kyoto University

Fig. 2. X, Y and XY distributuins.

used as a veto counter to remove the background electrons and positrons created upstream. The thickness of
the SSD is about 300 µm, and it converts bremsstrahlung
into electrons and positrons for the trigger scintillator.
Figure 2 shows the measured horizontal and verticalspatial distributions of the bremsstrahlung photons together with the two-dimensional spatial distribution at abeam energy of 150 MeV. About 8000 events were accumulated within 10 min. More detailed spatial distributions than the previous study1) are obtained. Since thistest experiment was performed without target ions, this
distribution represents bremsstrahlung generated fromresidual gases throughout the straight section of the electron storage ring. As was observed in the previous study,
the vertical distribution is sharper than the horizontal
one due to obstacles. The spread of the beam is about1000 ch, which coincides with 5 cm of the collimator hole.
At a next step, the spatial distributions will bemeasured with target ions. By comparing them with
GEANT4 simulation results, a precise value of ε will beobtained. In addition, the DAQ rate must be increased
by implementing the zero suppression mode. The acquisition rate is currently limited about 10 Hz at mostbecause the information of all channels of the SSD isrecorded in the current DAQ setup. Note that the beam
condition and corresponding ε change every moment,
and therefore, the spatial distributions have to be measured with a high DAQ rate for a short period in orderto obtain accurate total luminosities.
References

1) S. Yoneyama et al., RIKEN Accel. Prog. Rep. 48, 227 (2015).
2) S. Yoneyama, Master’s thesis (in Japanese), Tohoku University (2014).
3) T. Fujita et al., RIKEN Accel. Prog. Rep. 50, 188 (2017).

- 113 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Yield development with in-gas-jet laser ionization at KISS
Y. X. Watanabe,∗1 Y. Hirayama,∗1 H. S. Choi,∗2 M. Mukai,∗3 H. Miyatake,∗1 S. Iimura,∗4,∗5 M. Oyaizu,∗1
Y. Kakiguchi,∗1 N. Ishiyama,∗5 M. Wada,∗1 P. Schury,∗1 M. Rosenbusch,∗1 A. Taniguchi,∗6 J. H. Park,∗7 and
T. T. Yeung∗8,∗5
We are developing the KEK Isotope Separation System (KISS)1) to perform experimental studies suchas lifetime measurements, mass measurements, β-γ
spectroscopy, and laser spectroscopy for neutron-richnuclei around the closed neutron shell N = 126,
which is relevant to r-process nucleosynthesis. KISS
is an argon-gas-cell-based laser ion source, in whichthese neutron-rich nuclei are produced by multinucleon
transfer (MNT) reactions between a 136 Xe beam and198
Pt target.2) The beam is provided by RILAC2 +RRC with an energy of 9.4 MeV/nucleon on the target, which had a thickness of 12.5 mg/cm2 . The reaction products ejected from the target enter the gas
cell through a 5-µm polyimide window placed 10 mm
downstream from the target. The gas cell is ﬁlled with
1-atm argon gas, which thermalizes and neutralizes injected reaction products. They are transported to theexit of the gas cell by laminar gas ﬂow. In or out of thegas cell, these neutral atoms are irradiated by lasers forlaser resonance ionization. Two lasers are used: one isfor excitation, while the other is for ionization. One
speciﬁc element can be selected for ionization by tuning the wavelength of the excitation laser. These ions
are transported by radio frequency (RF) ion guides andaccelerated by a high voltage of 20 kV followed by adipole electromagnet for mass separation.
Since the neutron-rich nuclei of interest around N =126 are produced in rare channels of MNT reactions,
their eﬃcient extraction is essential for their measurements. Thus far, in-gas-cell laser ionization has been
used, in which two lasers are irradiated into the gascell. Recently, KU Leuven group demonstrated in-gasjet laser ionization with eﬃciency more than 10 times
that of in-gas-cell ionization.3) In-gas-jet laser ionization uses two lasers, which are irradiated on a gas jet
formed by a de Laval nozzle attached at the exit of
the gas cell. Low-temperature and low-pressure conditions in the supersonic jet could reduce the loss of ionscaused by their collisions with dense gas atoms. For
yield development at KISS, we introduced an in-gas-jet
∗1

∗2
∗3
∗4
∗5
∗6
∗7
∗8

Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator
Research Organization (KEK)
Department of Physics and Astronomy, Seoul National University
Department of Physics, University of Tsukuba
Department of Physics, Osaka University
RIKEN Nishina Center
Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS)
Rare Isotope Science Project (RISP), Institute for Basic Science (IBS)
Department of Physics, The University of Hong Kong

- 114 -

Fig. 1. KISS setup for in-gas-jet laser ionization.

laser ionization setup, as shown in Fig. 1. In order tosuﬃciently irradiate two lasers on the neutral atoms
of interest in the supersonic jet, the overlap among
them are optimized by arranging the excitation laser
collinearly with the gas jet, and the ionization laser
is perpendicularly reﬂected several times by two mirrors. An S-shaped RF quadrupole ion guide (SRFQ)
was introduced to enable the collinear injection of theexcitation laser. The SRFQ was segmented along theion transportation to apply an increasing electric potential from the upstream to the downstream because
a simulation with the SIMION code for the ion transportation indicated that ions stopped in the absenceof such an electric-potential gradient. The on-line experiment did not show increased extraction yields within-gas-jet laser ionization. When the same SRFQ wasused with in-gas-cell ionization, the count rates of extracted ions were the same between extraction withand without the electric-potential gradient. This result indicates that the initial ion velocities obtained
from the gas jet are not correctly evaluated in the simulation. We will further investigate the SRFQ designfor yield development with in-gas-jet laser ionization
through a more realistic simulation.
References
1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 412, 11 (2017).
2) Y. X. Watanabe et al., Phys. Rev. Lett. 115, 172503(2015).
3) R. Ferrer et al., Nat. Commun. 8, 14520 (2017).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Observation of charge-stripping of 20 keV/q ions upon injection into
gas cell cooler-buncher at KISS
P. Schury,∗1 T. Hashimoto,∗1,∗3 Y. Ito,∗4 H. Miyatake,∗1 J. -Y. Moon,∗1,∗3 T. Niwase,∗1,∗5 Y. Hirayama,∗1
M. Rosenbusch,∗1 M. Wada,∗1 X. Y. Watanabe,∗1 and H. Wollnik∗1,∗2

∗1
∗2
∗3
∗4
∗5

500

500

Offline reference
Online source

400

Counts / 6.4 ns

400

300
Counts / 6.4 ns

At the KISS facility, rare isotopes are produced
in-ﬂight by multi-nucleon transfer (MNT) reactions.
They are then stopped and neutralized in high pressure argon gas and transported by gas ﬂow to an exit
nozzle. Atoms of rare isotopes are then re-ionized inan element-selective manner by use of a 2-step laser excitation; the method can only produce singly-charged
ions. The gas cell system ﬂoats on a 20 kV bias, thereby
producing 20 keV/q ions. A magnetic separator withRm ≈ 900 ensures only a single isobar chain is transported downstream to the experimental apparatuses.
One of the primary experimental devices at KISS
is multi-reﬂection time-of-ﬂight mass spectrograph(MRTOF). The MRTOF, however, requires very lowenergy ions. To make the 20 keV/q KISS beam useable
by the MRTOF, a gas cell cooler-bucher (GCCB)1) has
been constructed. This device is similar in construction to a small rf carpet gas cell,2) but is windowless
and pressurized to only 1 mbar. The beam from KISS
stops in the GCCB, and is then extracted to vacuum
and transferred to the MRTOF. The MRTOF makes
rapidly interleaved time-of-ﬂight measurements of analyte (the beam from GCCB) and reference ions.
In the initial test of the GCCB, a 20 keV/q beamof 198 Pt+ was delivered from KISS. Figure 1 showsa time-of-ﬂight spectra measured during that study.
It was presumed that the peak at A/q = 99 was
198
Pt++ and a high-resolution follow-up measurement
conﬁrmed as much.
There are two ion traps between the GCCB and
MRTOF. While the ﬁrst of these has a very broadband response, the second trap (referred to as “ﬂattrap”) is somewhat mass selective. The amplitude of
the ﬂat trap was systematically varied to determine theprobability of conversion to a doubly-charged state. A
time-of-ﬂight spectrum was measured at each amplitude, and the number of singly- and doubly-charged A= 198 ions was recorded. The result, shown in Fig. 2,
indicates that ≈80% of incoming Pt ions were converted to the doubly-charged state.
From the occurrence of such charge-stripping reactions we presume the GCCB will also be highly eﬀective at breaking molecular contaminants which are acommon problem for gas cell based studies. We hope
to report on such an eﬀect in the near future.
KEK Wako Nuclear Science Center
New Mexico State University, USA
Institute for Basic Science, Korea
Japan Atomic Energy Agency
Kyushu University

300

200

100

200
80

90 100 110 120 130 140 150 160 170 180 190 200 210 220

m [u]

100

0
82

84

86

88

90

92

94

96

98

100

102

m [u]

Fig. 1. Time-of-ﬂight spectra from oﬄine test of KISS gas
cell cooler-buncher (GCCB) using a 20 keV/q beam of
198
Pt+ . The black spectrum shows the reference ions,85, 87
Rb+ and 133 Cs+ . The red spectrum shows the ionsdelivered from the GCCB, dominantly A/q = 99.

Fig. 2. Eﬀect of varying the RF amplitude of the ﬁnal
preparation trap before the MRTOF, indicating that
≈80% of the incoming beam is converted to a doublycharged state.

References

1) Y. Ito et al., JPS Conf. Proc. 6, 030112 (2015).
2) Y. Ito et al., RIKEN Accel. Prog. Rep. 49, 183 (2016).

- 115 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Reliable connection methods for gas piping and signal cabling of
PPAC in focal-plane vacuum chambers at BigRIPS
H. Sato,∗1 D. S. Ahn,∗1 N. Fukuda,∗1 T. Komatsubara,∗1 Y. Shimizu,∗1 H. Suzuki,∗1 H. Takeda,∗1 andK. Yoshida∗1
Two sets of parallel-plate avalanche counters(PPACs) are installed in each focal-plane vacuum
chamber at the BigRIPS and ZeroDegree separators.1)
For replacing the PPACs in a short time without any
trouble, we introduced reliable connection methods forgas piping and signal cabling inside the chamber: aquick coupling and a multipole connector, respectively.
The PPAC is filled with 10 Torr of gaseous isobutane
when in operation. The gas introduced from outsideof the chamber is transferred to the PPAC throughtwo Teflon tubes (for the inlet and outlet), and eachtube is inserted into a Wilson seal connector on the
PPAC. Because of the bad working environment due
to the narrow space of the chamber, a defect in the fitting of the Wilson seal may occur, causing gas leakage.
To avoid this, Full Flow Quick-Connects (Swagelok
SS-QF4-B-6M0 and SS-QF4-S-6M0) were adopted foreasy coupling (Fig. 1). The stems and bodies of the
Quick-Connects are attached to the PPAC and Teflon
tubes, respectively. A leakage test of the PPAC with
the Quick-Connects was performed by filling 10 Torr ofisobutane, and we observed no leakage in a vacuum of
5.5 × 10−5 Pa. In addition, no degradation of the vacuum occurred during the up-and-down motion of the










Fig. 1. Images of the Quick-Connects. (a) Ordinary gas
ports with Wilson seals. (b) New gas ports with thestems of Quick-Connects.
∗1

RIKEN Nishina Center- 116 -









Fig. 2. Images of signal cables with multipole connectors.
The shorter (200 mm) cables are connected to the
PPAC, and the longer (800 mm) cables are connectedto the chamber.

PPAC. We applied the Quick-Connects to the PPACs
in the F2, F3, F5, F7, F8, F9, F10, F11, and F12chambers during the autumn beam time in 2019.
For signal readouts, five coaxial cables (for anode, x1, x2, y1, and y2) are independently connected to the output ports of the preamplifier of
the PPAC. In addition, another cable for supplying a DC 12 V to the preamplifier is connected.
For easy and error-free connection, 14-pin multipole connectors (LEMO FGG.1B.314.CLAD76 andPHG.1B.314.CLAD76) were adopted (Fig. 2). Six
coaxial cables (RG178B/U) are soldered to one multipole connector. We performed the noise-level testingof the signal from the PPAC with the multipole connectors by using an alpha source 241 Am. As a result,the noise level of the signal was the same as that obtained with ordinary cabling. We applied the multipole connectors to the PPACs in the F3, F5, F7, andF8 chambers during the spring beam time in 2019.
We will finish the introduction of these two improvements to all the PPACs in 2020.
Reference

1) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Performance of a none-isochronous position-sensitive detector for the
Rare-RI Ring
R. Crane,∗1 S. Naimi,∗1 S. Hosoi,∗2 M. Mukai,∗3 H. F. Li,∗1,∗4 Y. Abe,∗1,∗5 D. Nagae,∗1,∗6 D. Hamakawa,∗2
Y. Inada,∗2 D. Kajiki,∗2 M. Sakaue,∗2 W. B. Tou,∗2 and K. Yokota∗2
We have developed a large area position-sensitive detector with a thin foil to be used for mass measurementwith the Rare-RI Ring.1) The principle of the detector operation is shown in the bottom of Fig. 1. Whenhigh energy beam passes through the thin foil, secondary electrons (SEs) are released and reﬂected by
the outer and inner mirror grids potential. The SEs
energy is determined by the acceleration grid placed
after the foil. The beam position is inferred from SEs
position measurement with the delay line MCP placed45◦ from the foil. To minimize the eﬀect of the SEs initial velocity, the detector has an isochronous design,2)which is achieved by careful choice of geometry and potentials: D/(L1 + L2 ) = 0.236Umir /Uacc , where Umirand Uacc are the acceleration and mirror potentials, respectively, D, L1 and L2 are dimensions of detector as
shown in Fig. 1. We have designed the detector to be
operated in the isochronous condition and also in thenone-isochronous condition, simply by modifying the
distance D between the inner and outer mirror grid.
In the isochronous detector operation D = 28 mm,
while for the none-isochronous operation D = 8 mm.
We have tested the detector at HIMAC with
200 MeV/nucleon 84 Kr beam in both isochronous (Iso)and none-isochronous (None-Iso) operation. For theIso detector we tested the performance for a grid pitchof 1 mm, while for the None-Iso detector 1 mm and
2 mm pitch were tested. The test results are summarized in Table 1. The detector position accuracy
is determined by the deviation from the foil image reconstructed by two PPACs. The position resolution isdetermined from a 2 mm diameter gate on the reconstructed foil image. For the mass measurement with
the Rare-RI Ring the accuracy and resolution of thehorizontal position are critical. The horizontal resolution of the None-Iso is better than the Iso detector.
The position accuracy of the None-Iso detector with
2 mm grid pitch is best, because we introduced a calibration mask in front of the foil to correct for any misalignment between the PPACs and the detector that
could result in a compromised position accuracy.

∗1
∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Department of Physics, Saitama University
Department of Physics, University of Tsukuba
IMP, CAS
National Institute of Radiological Sciences (NIRS), QST
Faculty of Sciences, Kyushu University

Beam 84Kr 200MeV/u

Trigger
Plastic

PPAC1

DL-E-MCP
chamber

PPAC2

Correction gridOuter mirror grid

D
Active area ofincident heavy ion

Beam

Inner mirror grid

45°
SEs

Conversion foil

L2

L1

Accelerating grid

SEs

Imaging area of SEs

MCP with position sensitive anodeFig. 1. (Top) Experimental setup at HIMAC consisting ofa trigger plastic scintillator, two PPACs and a vacuum chamber containing the DL-E-MCP. (Bottom)
Side view of the DL-E-MCP detector, where the beam
passage through the foil generates secondary electrons
that are reﬂected to the MCP with position-sensitive
delay line anode.
Table 1. The detector position accuracy Ax,y and resolution in sigma (σx,y ) are shown for both horizontal(x) and vertical (y) beam positions for diﬀerent detector operation; Isochronous (Iso.) and none-isochronous(None-Iso.). The performance of the latter is shown for
two diﬀerent grid pitch of 1 mm and 2 mm. The results
are shown for the same acceleration potential and different optimized mirror potential in each conﬁguration.

Ax [mm]Ay [mm]σx [mm]σy [mm]Iso.
1 mm pitch
+4.0
−0.1
3.5
2.2

None-Iso.
1 mm pitch
+1.5
0.0
2.4
2.9

None-Iso.
2 mm pitch
−0.8
+0.6
2.9
4.5

References
1) Z. Ge et al., RIKEN Accel. Prog. Rep. 50, (2017).
2) N. Nankov et al., Wiss. Tech. Berichte (Annual Report2004) FZR-423, 25 (2005).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Intermediate Tracker Integration in sPHENIX
D. Cacace,∗2 Y. Akiba,∗1 K. Cheng,∗3 E. Desmond,∗2 T. Hachiya,∗1,∗4 T. Kondo,∗5 C. Kuo,∗3 M. Lenz,∗2
E. Mannel,∗2 C. Miraval,∗2 M. Morita,∗4 I. Nakagawa,∗1 R. Nouicer,∗2 R. Pisani,∗2 M. Shibata,∗4 C. Shih,∗3
A. Suzuki,∗4 T. Todoroki,∗1 X. Wei,∗6 and R. Xiao∗6
The sPHENIX collaboration at RHIC is constructing a major upgrade to the PHENIX detector, consisting of an entirely new spectrometer based on theformer BaBar solenoid magnet and the PHENIX facilities and infrastructure.1) The upgrade will allow for
an in depth jet and beauty quarkonia physics program
to address the fundamentals of strongly coupled quarkgluon plasma. The solenoid magnet is sandwiched byhadronic calorimeters (HCal) followed by an electromagnetic calorimeter (EMCal). Inward of the EMCal
is a time projection chamber (TPC), INTermediate silicon strip Tracker (INTT) and MAPS-based VerTeX
detector (MVTX) composing the sPHENIX tracking
system. All of the subsystems have their challenges
when coalescing with one another, but the INTT is ofparticular interest in terms of integration considerations.
The INTT design, constrained by its neighbors, hasbeen heavily influenced by the other sPHENIX tracking components. The MVTX’s active region has anouter diameter of 10.5 cm and has a service cone longitudinally starting at 25 cm from the vertex and grows
to a diameter of 21.5 cm. The TPC has an inner diameter of 40 cm that spans a length of 117 cm from thevertex in both directions. The INTT has to fit between
these envelopes. The INTT detector itself consists ofthree main components each consisting of several subcomponents as seen in Fig. 1.
The first main component is the active region containing the silicon sensors. Four sensors are wire
bonded to 52 FPHX chips1) which are wire bonded
and epoxied to two high-density interconnects (HDI)
and both are epoxied to a stave for structural support.
This assembly, known as a ladder, as seen in Fig. 2,
covers an acceptance of pseudorapidity of ±1.1. Several ladders arranged tangentially to a circle aroundthe vertex compose what is referred to as a barrel.
The active area of the sensors is approximately half
the width of the HDI, which lends itself to a configuration where two barrels are required to obtain hermetic
2π azimuthal coverage, referred to as one layer. The
detector consists of four barrels or two layers at approximate radial positions of 7.2, 7.7, 9.7 and 10.3 cm
from the beam axis. The layers are held in position
∗1

∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Brookhaven National Laboratory
National Central University
Nara Women’s University
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University- 118 -

Fig. 1. INTT in sPHENIX 3D model cross section.

Fig. 2. INTT ladder 3D model.

with a series of stave end-caps and end-rings.
The end-rings also attach the barrels to the second
main component, the service barrel. The service barrel, consisting of two carbon fiber tubes and miscellaneous brackets, carries the services (cables, cooling,
nitrogen, etc.) from the ladders to beyond the TPC
volume. The cables terminate just beyond the TPC
and connect to the readout cards (ROC). The coolingand nitrogen connect to manifolds beyond the TPC.
From there all the services are routed to the respective
racks and/or infrastructure facilities. The outside of
the service barrel also has features that allow for thedetector and service barrel to installed as a singularunit.
Lastly, the third main component of the INTT is its
support structure. Consisting of a carbon fiber tube
and aluminum I-beams, the support structure facilitates the installation and operation of the INTT andall of its services. The I-beams connect the carbon fiber
tube to the inner HCal creating a direct load path forthe detector and direct service routing to the INTT’s
racks. The I-beams also support the ROCs at an appropriate location for the HDI extension cables thathave a maximum length of 120 cm.
Prototype ladders are being produced to verify thedesign and assembly fixtures for production.2) Prototype end-rings will be produced in conjunction with theladders to verifying the barrel configurations. The service barrel and support structure designs are far along
and are continuously being verified that they properly
integrate with the surrounding sPHENIX detectors.
References
1) sPHENIX Conceptual Design Report (2018), https://indico.bnl.gov/event/4625/attachments/18432/23516/
sphenix-conceptual-design_051918.pdf .
2) C. Miraval et al., in this report.

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Assembly of Intermediate Silicon Tracker in Taiwan
C. Shih,∗3 Y. Akiba,∗1 D. Cacace,∗2 K. Cheng,∗3 E. Desmond,∗2 T. Hachiya,∗1,∗4 S. Hasegawa,∗5 T. Kondo,∗6
C. Kuo,∗3 M. Lenz,∗2 E. Mannel,∗2 C. Miraval,∗2 M. Morita,∗4 I. Nakagawa,∗1 R. Nouicer,∗2 R. Pisani,∗2
M. Shibata,∗4 A. Suzuki,∗4 T. Todoroki,∗1 X. Wei,∗7 and R. Xiao∗7
The INTermediate Tracker (INTT) is the tracker
system between the Time Projection Chamber (TPC)and the MAPS-based Vertex Detector (MVTX). INTT
makes up the gap between TPC and MVTX, it can precisely reconstruct the track of charge particles. One
INTT ladder consists of 59 components, 1 stave, 2-highdensity interconnects (HDIs), 52 readout chips and 4 silicon sensors. All the components will be ﬁxed by glueand screws. A ladder assembly is performed in the following sequence. 1), Fix the readout chip on HDI bysilver epoxy with 26 chips per HDI. 2), Bond the readout chips to HDI using a bonding machine and checkthe response to slow control commands in a test bench.
3), assemble HDI with readout chips onto stave by thermal glue and screws. 4), Assemble silicon sensors onto
the ladder by silver epoxy. 5), Bond the silicon sensors toreadout chips by a bonding machine and check the FPHX
response again and also silicon sensor performance. 6),
Apply an encapsulation to protect the bonding wires.
The National Central University (NCU) in Taiwan is responsible for one-third of the INTT ladder production.
The assembly procedures 1) and 2) are planned to becovered by a private company in Taiwan, and the remaining procedures will be conducted in a clean-room
facility at the National Taiwan University (NTU). Figure 1 shows the gantry to be used for the assembly in
NTU, which consists of a large ﬂat table with a fourdimensional robotic gantry head. The gantry head isequipped with an optical microscope, which allows a calibration error in position to be the order of 10 µm. Thusfar, the assembly procedure requires 9 tools, as shown

Fig. 1. Photo of the clean room in NTU. Gantry, bonding
machine and optical gaging products (OGP) microscope
are all available.
∗1
∗2
∗3
∗4
∗5
∗6
∗7

RIKEN Nishina Center
Brookhaven National Laboratory
National Central University
Nara Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University

Fig. 2. The designs of the prototype of INTT ladder assembly
tools, the assembly tools family.

Fig. 3. Assembly tools already fabricated by AS CNC.

in Fig. 2. The assembly unit is one ladder, and thedesigns of all prototype assembly tools have been completed. The idea is to assemble the entire ladder on theladder assembly tray, while HDIs and silicon sensors areplaced on the HDI sample tray and sensor sample trayby hand, respectively. Pick up tools are used to pick up
the HDI and silicon sensors via the vacuum system andmove them to the stave by the gantry. An order for thetools has already been submitted to the Academia Sinica(AS) computer numerical control (CNC) factory. The
production of 5 has been completed, as shown in Fig. 3.
The assembly exercise and bonding exercise are scheduled to start simultaneously in early March. A dummy
HDI, dummy silicon sensor, and dummy stave have also
been produced, which are suﬃcient for the exercise. Two
important aspects namely, the type of glue and the procedure to apply the glue, are uncertain and need to be
determined. Both are expected to be ﬁnalized at theend of March. A new INTT test bench has been set up
in NCU, and a few checks are to be made to be fully
functional.
The conclusion for the INTT assembly in Taiwan isthat we aim to provide one functional complete ladderfor INTT phase - 3 Test Beam at 22th April.
References

1) Conceptual Design Report of sPHENIX (2018).
2) The PHENIX Forward Silicon Vertex Detector.

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Development status of long data cable for sPHENIX-INTT detector
T. Hachiya,∗1,∗2 Y. Akiba,∗1 D. Cacace,∗3 K. Cheng,∗4 E. Desmond,∗3 S. Hasegawa,∗5 T. Kondo,∗6 C. Kuo,∗4
M. Lenz,∗3 E. Mannel,∗3 C. Miraval,∗3 M. Morita,∗2 I. Nakagawa,∗1 R. Nouicer,∗3 R. Pisani,∗3 M. Shibata,∗2
C. Shih,∗4 A. Suzuki,∗2 T. Todoroki,∗2 X. Wei,∗7 and R. Xiao∗7
The intermediate tracker (INTT) is a silicon strip
barrel detector for the sPHENIX experiment.1) INTT
requires a special extension cable for data transfer between the INTT module and readout electronics. The
data cable must satisfy the following requirements toﬁt the tight space available for INTT at the sPHENIX
detector: (1) ﬂexibility, (2) a very long length ofat least 120 cm, (3) high-density signal lines (128lines/5 cm width), and (4) high-speed signal transfer(by LVDS).2) The development of the cable is the mostchallenging part of the INTT project.
We performed research and development of the cable in the past two years. The design of the cable was
optimized using a signal-transfer simulation with thestrip-line structure. We then made a prototype of thecable using a ﬂexible printed circuit board (FPC) witha liquid crystal polymer (LCP) as the substrate. The
LCP realizes a small signal loss because of its small
dielectric constant. The electrical and mechanical performance of the prototype were tested.2) Based on thisknowledge, we made a 120-cm-long prototype cable.
We measured the eye diagram to study the transfer
performance of the cable. Figure 1 shows the input(left) and output (right) shapes of the eye diagrams.
The signal height is 30% attenuated, and the waveformis rounded. This change in waveform is consistent withthe expectation from simulation. We found that theeye is clearly open. To quantify the performance, wewill measure the bit error rate.
In June 2019, we performed a beam test with a
120 GeV proton beam at the Fermilab Test Beam Facility (FTBF). The performance of the INTT module
Input signal

Output from the data cable

Fig. 1. Eye diagram with (right) and without (left) the
cable.
∗1
∗2
∗3
∗4
∗5
∗6
∗7

RIKEN Nishina Center
Nara Women’s University
Brookhaven National Laboratory
National Central University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University- 120 -

Sensors in a dark box

Readout Electronics

Long data cables

Fig. 2. Setup for testing the cable during the beam test at
FTBF.

was evaluated in terms of the detection eﬃciency andminimum ionizing particle (MIP) peak.3) In addition,
the prototype cable was tested under a beam environment. The data were taken using the cable together
with the INTT module and, later, readout electronics. Figure 2 shows the test setup at the beam test.
The INTT modules are installed in a dark box, andthe readout electronics are placed. The cable, shownas an orange ﬂat cable that makes loops, is connectedto them. This was the ﬁrst attempt to take data withthe full readout chain of the INTT detector. Further
investigation is ongoing to quantify the performance
under the beam environment.
An issue was found in the production of throughholes on the cable. We found that the through holes
have nodules caused by the residue of the adhesive
sheet used to laminate the FPC layers. Several attempts to clean the through holes by changing the drill
process and desmear process were unsuccessful. We
will test new adhesive sheets from diﬀerent manufacturers. These sheets are suitable for LCP according to
the catalog.
In summary, the development of an extremely longand high-density cable is in progress. The production
version of the cable was made and tested under a beam
environment. An issue is under investigation. We will
test new adhesive sheets, and a new prototype will bemade using a new adhesive sheet and tested during thebeam test in May 2020.
References

1) I. Nakagawa et al., in this report.
2) T. Hachiya et al., RIKEN Accel. Prog. Rep. 52, 128 (2019).
3) A. Suzuki et al., in this report.

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Performance evaluation of a sensor module for INTT at sPHENIX
A. Suzuki,∗1 Y. Akiba,∗2 D. Cacace,∗3 K. Cheng,∗4 E. Desmond,∗3 T. Hachiya,∗2,∗1 S. Hasegawa,∗5 T. Kondo,∗6
C. Kuo,∗4 M. Lenz,∗3 E. Mannel,∗3 C. Miraval,∗3 M. Morita,∗1 I. Nakagawa,∗2 R. Nouicer,∗3 R. Pisani,∗3
M. Shibata,∗1 C. Shih,∗4 T. Todoroki,∗2 X. Wei,∗7 and R. Xiao∗7
The intermediate silicon strip tracker (INTT) is oneof the tracking detectors of sPHENIX.1) An INTT sensor module consists of a silicon strip sensor, a readout chip called FPHX and a high-density interconnect(HDI).2) The size of the silicon strip sensor is 232.2 ×
22.5 × 0.32 mm3 . FPHX is a read-out LSI chip used
for PHENIX.1) One FPHX reads out 128 channels. 26
FPHXs correspond to 128 × 26 read-out channels. Eachchannel is equipped with a shaping ampliﬁer and 3-bit
ADC. HDI is a ﬂexible PC board.
We performed a beam test using a 120 GeV proton
beam in June, 2019 at Fermilab and analyzed the data
to evaluate the performance of the INTT sensor module.
Figure 1 shows the setup of three sensor modules and two
trigger scintillators. We call the layers from the front of
the beam direction L0, L1 and L2. Two scintillators arearranged to sandwich the sensor modules.
We deﬁne the eﬃciency of L0 by Eq. (1) and describe
how to calculate the eﬃciency. (1) Figure 2 shows thehit channel distributions for 26 FPHXs in a layer. The
beam spot was observed at chip 6, 7, 19 and 20, respectively. L1 and L2 required a single strip hit at chip 6
and ADC > 3 to reduce noise. An L0 hit can be multistrip hits among several chips around the beam spot. (2)We calculate the channel diﬀerence between L1 and L2
to choose the coincident hit from the track. Figure 3(a)shows the hit correlation between L1 and L2 so thatevents of channels with a diﬀerence <±5 are selected foras shown in Fig. 3(b). (3) We calculate the hit expectation of L0 using L1 and L2 hits by using Eq. (2) to search
for the most probable hit at L0. (4) We search for a corresponding hit at L0 to choose the one closest to the hit
expectation. L0 channels are numbered from 0 to 256
by combining two FPHX chips to cover the whole widthFig. 2. Hit channel distribution of L0. X-axis: entries, Yaxis: channel number.

Fig. 3. (a) Hit correlation between L1 and L2. X-axis: L1channel, Y-axis: L2 channel. (b) Diﬀerence (L1 channel L2 channel). (c) Hit correlation between L0 and expectation. X-axis: L0 channel, Y-axis: expected channel. (d)Diﬀerence (L0 channel - expected channel).

of the sensor. Figure 3(c) shows the hit correlation of
L0 with the expectation so that events of the closest hitof channels with a diﬀerence <±5 are selected as shown
Fig. 3(d). (5) The events of (2) as the denominator and(4) as the numerator for Eq. (1) are counted. The detection eﬃciency is evaluated as 96.0±0.5%, which is within
the error margins of the value of 96.4 ± 1.0% obtained in
the previous experiment conducted in 2018.
L0 Eﬃciency =N(L0hit ∩ L1hit ∩ L2hit ).
N(L1hit ∩ L2hit )L0exp = L1chan × 3 − L2chan × 2.

Fig. 1. Setup of ladders and scintillators in the beam test.
The orange arrow indicates the beam direction.
∗1
∗2
∗3
∗4
∗5
∗6
∗7

Nara Women’s University
RIKEN Nishina Center
Brookhaven National Laboratory
National Central University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University

(1)
(2)

In summary, we analyzed the beam test data to evaluate the eﬃciency of the INTT sensor module. The eﬃciency of L0 is 96.0 ± 0.6%. This result is consistent withthe 2018 result.
References

1) I. Nakagawa et al., in this report.
2) C. Aidata et al., Nucl. Instrum. Methods Phys. Res. A
755, 44–61 (2014).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Sensor testing of Intermediate Silicon Tracker
K. Cheng,∗3 Y. Akiba,∗1 D. Cacace,∗2 E. Desmond,∗2 T. Hachiya,∗1,∗4 T. Kondo,∗5 C. Kuo,∗3 M. Lenz,∗2
E. Mannel,∗2 C. Miraval,∗2 M. Morita,∗4 I. Nakagawa,∗1 R. Nouicer,∗2 R. Pisani,∗2 M. Shibata,∗4 C. Shih,∗3
A. Suzuki,∗4 T. Todoroki,∗1 X. Wei,∗6 and R. Xiao∗6
The Intermediate Silicon Tracker (INTT) uses a multichannel silicon sensor to record tracks of charged particles. The characteristics of all channels should be measured to determine the performance before assembly.
Some coarse quality assurances of every sensor are madeby Hamamatsu Photonics K.K. before delivery, including total IV and CV measurements of combined multiple
channels. Individual channels are then tested at the National Central University (NCU) in Taiwan.
A half ladder of the INTT detector has 26 chips, andeach chip has 128 channels. If we use a micropositioner
to touch the sensor channel by channel, the measurement
time will be huge. Furthermore, in this method, it is difﬁcult to control the touch force on AC pads, resulting
in severe damage to the pads. A major scratch on an
AC pad can cause a fatal problem in the wire bond to
the pad in an assembly process. The best solution is touse a probe card to connect 128 channels simultaneously
and then pass through the relay matrix to scan eachchannel. We only need to raise the voltage once in one
chip and keep the voltage to measure other channels. To
avoid severe scratching on bonding pads in this testingprocess, we employ a probe station (MPI TS200) thatcan control the contact force of the probe. When heightis deﬁned, the repeatability of the machine is smaller
than 2 µm, and the contact force is controlled by a machine, rather than a human hand. Because INTT siliconsensors have an AC-coupling design, all of the leakage
current originating from silicon will be blocked by a capacitor between silicon and the readout metal. The mostimportant measurement is, thus, the capacitance of eachchannel for the AC-coupling silicon sensors. To measure the capacitance, the silicon sensor should be fully
depleted.1) In the AC-coupling silicon sensor structure(Fig. 1), the AC pads and silicon are isolated; therefore,

Fig. 1. Schematic of the AC coupling sensor.
∗1
∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Brookhaven National Laboratory
National Central University
Nara Women’s University
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University

Fig. 2. CV curves of all channels in one chip. The blue markers show the result of connecting the DC pad to 0 V, andthe red lines show the result of connecting the bias ringto 0 V.

Fig. 3. Channel distribution of capacitance at full depletion.
The red circles show the values obtained with the bias
ring connected to 0 V, the blue and cyan circles show
the value with the DC pads of channel-1 and channel-128
connected to 0 V.

we need a contacting bias ring to create a closed circuit
to ensure full depletion. However, using a probe card totouch the readout pads and bias ring together is diﬃcult
because the contact window only opens at four cornersof the full sensor. Therefore, the coordinates of the window are not constant for each chip. Now, we change theconnection to the DC pad to 0 V create a circuit. In
the ﬁrst study, the capacitance diﬀerence is only 0.5 pF
between the connections to the bias ring and DC pad.
CV curves (Fig. 2) and the channel distribution of capacitance (Fig. 3) measured with two methods in one
chip show almost the same behaviors, thus suggestingthat the DC pad provides a reasonably consistent 0 V
contact point as the bias ring with an extra oﬀset of∼0.5 pF. Figure 3 shows that the capacitance is independent of which channel is connected to 0 V; therefore,a one-pin connection to the DC pad should be suﬃcient.
Therefore, the probe card will have 129 pins: 128 forthe measurement of the AC readout and one for the DC
pad. Subsequently we can determine the existence ofbad strips on the sensor and mark them.
Reference

1) R. Nouicer et al., Nucl. Instrum. Methods Phys. Res. A
461, 143–149 (2001).

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RIKEN Accel. Prog. Rep. 53

Geant4 simulation of INTT Phase-2 Test Beam at Fermilab
C. Shih,∗3 Y. Akiba,∗1 D. Cacace,∗2 K. Cheng,∗3 E. Desmond,∗2 T. Hachiya,∗1,∗4 S. Hasegawa,∗5 T. Kondo,∗6
C. Kuo,∗3 M. Lenz,∗2 E. Mannel,∗2 C. Miraval,∗2 M. Morita,∗4 I. Nakagawa,∗1 R. Nouicer,∗2 R. Pisani,∗2
M. Shibata,∗4 A. Suzuki,∗4 T. Todoroki,∗1 X. Wei,∗7 and R. Xiao∗7
The INTermediate Tracker (INTT) is the tracker system between the Time Projection Chamber (TPC) andthe MAPS - based Vertex Detector (MVTX). It makes
up the gap between the TPC and the MVTX, and it
can produce the track reconstruction of charged particles
more precisely. To check the performance of the INTT
modules, a beam test of INTT phase-2 was conducted in
Fermilab in May 2019. Protons at 120 GeV were used in
the test beam. Geant4 is applied to check the analysis
results. The geometry of the INTT beam test in simulation is shown in Fig. 1. There are 4 layers of INTT
modules, each of which is formed by 2 silicon sensors,
HDI, and a cooling system. The air gap between twolayers is 35 mm. The INTT modules are sandwiched bytrigger scintillators, one in the front and one in the back.
The readout chips and glue layers are not considered in
the simulation.
The beam is set to be perpendicular to the modules
in the ﬁrst simulation. To be consistent with the actual
data analysis of the beam test, only events that ﬁre asingle strip in layer 1 were selected in MC. A comparisonof energy deposit distributions is shown in Fig. 2. The
horizontal scale for MC is adjusted to match the MIP
peak position. The result shows that MC is wider thanthe data. In order to investigate the discrepancy, the injection angle theta of the beam is scanned from 0 to 2.81
degree with 0.01 degree step in the second simulation.
For most cases, the distribution of energy deposit is similar to that of the ﬁrst simulation. However, we foundthat the shape of the distribution changes once the an-

Fig. 3. Left: Distribution of energy deposit, beam theta angle
is 1.26 degree. Right: the schematic of event display.

Fig. 4. Beam spot distribution of INTT Test beam.

Fig. 5. Real energy deposit distribution.

Fig. 1. Geometry of INTT Test Beam in simulation.

Fig. 2. Distribution of energy deposit, the beam direction is
set to be perpendicular to modules.
∗1
∗2
∗3
∗4
∗5
∗6
∗7

RIKEN Nishina Center
Brookhaven National Laboratory
National Central University
Nara Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University

gle passes a threshold, as illustrated in the right panel ofFig. 3. The proton starts to ﬁre multiple strips, and thepass length of the primary strip becomes shorter than in
the perpendicular case. Consequently, the MIP peak of
the MC shrinks and leads to better agreement with thedata, as demonstrated in the left panel of Fig. 3. The
beam information of the phase-2 beam test is recordedby three wire chambers, and the beam spot is in Fig. 4,
the sigma is 0.0025 degree. Thus, the beam information
is optimized.
The second step is to reproduce the most probablevalue (MPV) of energy deposit. The function to convert
data from mV to KeV is 0.075 * mV = KeV. The MPV
ratio of the data and MC is 56.5%, the plot is shown in
Fig. 5.
In conclusion, the simulation indicated that the beam
was not injected at a perfectly perpendicular condition to
the INTT modules. The next step is to feed the beamspot distribution to a simulation with a diﬀerent angle
and to ﬁnd the angle between the beam direction andmodules. In the phase-3 INTT test beam, the gain andtiming setting needs to be checked.
Reference

1) Conceptual Design Report of sPHENIX (2018).

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RIKEN Accel. Prog. Rep. 53

Development of high-resolution hard X-ray detector system by usingtransition-edge sensor for accelator-based experiments
T. Isobe,∗1 H. Kaori,∗2 T. Okumura,∗1 S. Okada,∗1 S. Yamada,∗3 H. Tatsuno,∗3 D. A. Bennett,∗4
J. A. B. Mates,∗4 D. Yang,∗4 D. S. Swetz,∗4 and T. Hashimoto∗5 for the HEATES collaboration
A transition-edge sensor (TES) is a type of lowtemperature microcalorimeter that provides a muchbetter energy resolution than semiconductor detectors by using a superconducting material as thetemperature sensor at the superconducting-to-normaltransition-edge. Recently, a detector system with TES
was employed for accelator-based experiments.1) For
instance, a high-resolution X-ray measurement of a
Kaonic atom was succesfully performed at J-PARC in
spring 2018.2) An energy resolution of 5.7 eV in FWHM
was shown for the Co Kα X-ray line (6.9257 keV)during the beam time, while a resolution of 5 eV in
FWHM can be achieved for the same line with thebeam oﬀ. As the next step of high-resolution X-ray
spectroscopy with a TES detector system for accelatorbased science, we are constructing a new system byindroducing a modern cryogenic system (HPD Co.
Ltd. model 107 adiabatic demagnetization refrigerator, ADR, cryostat) and novel microwave readout system for TES. The model 107 cryostat has a helium3-backed, single-stage ADR with an ADR base temperature of 30 mK and a 300-h no-load regulation at
100 mK. Figure 1(a) shows the inside of the new cryogenic system.
The sensitivity of the TES is expressed as ∆T =E/C, where ∆T is the temperature change, E the energy of X-rays, and C the heat capacity of the TES.
Thus, the size of the TES, which determines C, is limited for a target performance. Typically, the size of
one pixel is 100 × 100 µm2 . In order to enlarge the acceptance of the detector, it is necessary to increase thenumber of TES pixels (readout channel). However,the number of electric connections to the cryostat islimited to less than ∼100 due to the limitation in cooling power of the cryogenic system. Recently, a novel
readout technique using a microwave resonator was developed.3) By introducing such microwave readout, thenumber of readout channels is expected to be increased
up to ∼1000 per readout connection. Figures 1(b) and(c) show the transmitted power of the prototype resonator, which gives 64 tones, where one tone is used
for one TES pixel readout.
After ﬁnishing the construction of the new detector system, we plan to execute online experimental
projects for the precise measurement of hard X-ray
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
National Institute of Advanced Industrial Science and Technology (AIST)
Graduate School of Science, Tokyo Metropolitan University
National Institute of Standards and Technology (NIST)
Japan Atomic Energy Agency (JAEA)- 124 -

Fig. 1. (a) New cryogenic system to introduce the novel
TES detector. The top plate is used for vacuum sealing.
The other plates are used for shielding thermal radiation of 300 K, 3 K, and 300 mK from top to bottom.
The TES detector is supposed to be mounted on thebottom part indicated by dashed square. (b) Transmitted power of the prototype resonator. Each tone corresponds to one channel (TES pixel). (c) Enlarged viewof the X-axis of (b). (d) Prototype resonator mounted
in model 107.

lines from atomic/nuclear excited states. For example,
X-rays from a muonic atom will be measured for thevalidation of quantum electromagnetics. Furthermore,
X-rays from the excited isomeric state of Th-229 are
proposed to be measured. Currently, a molybdenumgold bilayer TES microcalorimeter for X-rays in therange of 20 keV to 45 keV X-rays has been designed,
and its prototype has been tested.
This work is supported by the Japanese MEXT
KAKENHI under grant No. 18H05458 and No.
18H03713.
References

1) S. Okada et al., Prog. Theor. Exp. Phys. 2016, 091D01(2016).
2) T. Hashimoto et al., J. of Low Temp. Phys. 199, 1018
(2020).
3) J. A. B. Mates et al., Appl. Phys. Lett. 92, 023514 (2008).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

SAMURAI DAQ speed improvement
J. Gao,∗1,∗3 H. Baba,∗1 M. Sasano,∗1 and L. Stuhl∗2
1000

t1

n
ve

t3

t2

n
ve

t4

n
ve

n
ve

edead time

e

e

e

t1

t2

t3

t4

Δt1=t2-t1

Δt2=t3-t2

Δt3=t4-t3

……

time

Fig. 1.: Deﬁnition of the time interval between neighboring events ∆t.
∗1
∗2
∗3

RIKEN Nishina Center, Japan
Center for Nuclear Study, University of Tokyo, Japan
School of Physics, Peking University, China

count

500

15000
10000
5000

250
160

count

750

Δt(µs)

20000

6000
500

4000
2000

250
160

0

0
0

250

500

size

750

1000

(a) PDC

0

250

500

size

750

1000

(b) BDC

Fig. 2.: Plot of ∆t versus data size for SAMURAI30
data. A comparison of the ﬁgures indicates that PDC
limits the DAQ performance.

dead time(size = s) = inf{∆ti |sizei = s}.
With pairs (sizei , ∆ti ) of each event, where sizei isthe data size of the device of interest for event i and∆ti is deﬁned in Fig. 1, we can draw a 2D histogram.
For example, Fig. 2 shows two plots generated fromSAMURAI30 experiment1) data. In this example, thehistogram for the proton drift chamber (PDC) has a linear edge, but that for the beam drift chamber (BDC)
appears to have a plateau on the small data size side.
This implies that BDC should wait for other device(s)to ﬁnish data saving when it has a small amount of data.
We conclude that PDC is the bottleneck and should be
improved. We can repeat these steps to optimize DAQ
performance until all devices show a linear edge on thehistograms or the dead time becomes low enough for theexperiment.
This method is also useful for comparing the performance of diﬀerent modules. For example, Fig. 3(a) and
Fig. 3(b) show the results for two widely used TDCs,

1000

750

Δt(µs)In this contribution, we report the improvement of
the SAMURAI DAQ speed. SAMURAI DAQ contains
several VME subsystems. The typical dead time wasabout 200 µs. It is necessary to improve the DAQ system
to acquire suﬃcient data for recent studies.
The accurate measurement of dead time is critical forthe performance improvement. Conventionally, we estimate the typical dead time by checking the width of busy
signals using an oscilloscope. However the width can be
diﬀerent for events with diﬀerent data sizes. Therefore
we developed a new method to evaluate the dead time
as a function of data size using saved data. This method
helps us ﬁnd the device that critically limits the DAQ
speed.
The data size is easy to obtain from the data ﬁle, while
the dead time can be extracted from event time-stamps.
Let ∆t be the time interval between neighboring events(see Fig. 1). If we acquire a large amount of data, we
can expect some events to be accepted immediately after
the dead time is ﬁnished (like event 3 in Fig. 1).

(a) AMT-VME(b) V1190

Fig. 3.: Plot of ∆t versus data size for source test data.
AMT-VME TDC has a larger slope, implying that its
performance is worse.
AMSC AMT-VME TDC and CAEN V1190 TDC, respectively. We performed a source test for each TDC
and plotted the resulting 2D histograms. The edge in the
AMT-VME’s histogram exhibits a sharper slope, which
implies that the dead time of this module quickly increases when the data size increases. We emphasize herethat it would be very diﬃcult to recognize this performance diﬀerence through an oscilloscope measurement.
We applied this method to optimize DAQ for the
SAMURAI 11 experiment.2) According to the results
shown in Fig. 3, the DAQ speed was limited by the TDC
modules, rather than the detectors. Therefore in the experiment, all AMT-VME TDCs were replaced by V1190
TDCs. Combined with other optimizations, such as thedisabling of unnecessary TDC headers, the typical deadtime in SAMURAI 11 was about 50 µs, and the accepted
trigger rate was about 5 kHz. This is a large improvement over previous experiments in SAMURAI, which
typically had a dead time of about 200 µs and accepted
trigger rate of about 1 kHz.
(This work is funded by the China scholarship Council.)
References

1) L. Stuhl et al., RIKEN Accel. Prog. Rep. 52, 33 (2018).
2) M. Sasano et al., in this report.
- 125 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

High-stability high-voltage power supply for MRTOF†
P. Schury,∗1 M. Wada,∗1 H. Wollnik,∗1,∗2 J. -Y. Moon,∗1,∗3 T. Hashimoto,∗1,∗3 and M. Rosenbusch∗1
1
Allan deviation [ppm]

Achieving the highest possible mass resolving power
in a multi-reflection time-of-flight (MRTOF) mass
spectrograph requires very high-stability power supplies. To this end, we have developed a programmablehigh-voltage power supply that can achieve long-term
stability on the order of parts-per-million. We havedemonstrated that in the ≤1 Hz band the output stability is on the level of 1 part per million (ppm) during one hour, with only slightly more output variation
across 3 days. We have further demonstrated that theoutput is largely free of noise in the 1 Hz–200 Hz band.
We have also demonstrated settling to the ppm levelwithin one minute following a 100 V step transition.
Finally, we have demonstrated that when these power
supplies are used to bias the electrodes of an MRTOF
the measured time-of-flight is stable on the ppm-level
for at least one hour.
In order to achieve a fast-settling, high-precision,
long-term stable high-voltage power supply for driving our MRTOF, we have extended the concept laidout in the Voltage Multipliers, Inc, application note
“AN-0300 - High Voltage Op-Amp Application Using
Opto-Couplers,1) ” which describes the use of infrared
LEDs and high-voltage photodiodes to emulate an operational amplifier with up to 15 kV power supply span.
A conceptual circuit diagram of our design, separated
into functional blocks, is given in Fig. 1.
A crate of 16 power supplies was built to bias the

20-bit DAC

16-bit digital
thermometer
5.000 V

5.000 V

5.000 V

5.000 V

+
-

-

+5 kV

D1

Filter

U4

R LED

Q2

+

50 kΩ

49.95 MΩ

Rg

Rf

Cfb

D2

D4
-5 kV

-

Precision resistive divider

Q1

10 nF

+

+15 V

D3

1MΩ

R'g

R'f

Low-noise reference

Vout

Vset

Gain adjustment
+

-15 V

Regulation circuit with"high-voltage op-amp"

∗1
∗2
∗3

0.1

1

10
Cluster time [s]

100

1,000

Fig. 2. Allan deviation from individual ion times-of-flight.
The PID regulation without and with RC filter exhibit
a slope approximating white noise to ≈1 s and ≈10 s, respectively. The dashed line indicates the trend expected
for white noise. The Allan deviation curve switches
to a flat line indicative of flicker noise at a level of≈0.02 ppm, which coincides with the 0.1 ns raw bin
width from the TDC.

electrodes of 50 cm MRTOF-MS in the E3 (KISS)
vault. The voltages were adjusted until a time resolvt≈ 250,000 was achieved. Due to theing power of ∆tlens voltage requiring a bias of 5 kV or more, we havethus far opted to use an NHR 42 60r high-precision±6 kV power supply from ISEG to bias this electrode.
Figure 2 shows the result of an analysis of timeof-flight data from a several-hours-long measurement
using our newly developed power supplies with the
MRTOF in E3 along with a similar analysis using
pre-existing hours-long duration data from our fullsize MRTOF-MS operated with a PID stabilization
scheme. The data for the PID stabilization was obtained using a 30 ms cycle period, yielding a minimum
Allan deviation2) sampling period of ≈80 ms. The data
for the present system was obtained using a 15 ms cycle
period, yielding a minimum Allan deviation sampling
period of ≈40 ms. These analyses shows that in termsof long-term stability the voltage stabilization circuitof the present work exceeds the performance of our RC
filter enhanced PID regulation system. Using our new
power supplies, the MRTOF exhibits white noise in
the ion time-of-flight over a much wider duration thanwith the PID-based regulation systems.
References

1) “AN-0300 - High Voltage Op-Amp Application Using
Opto-Couplers,” Voltage Multipliers, Inc, http://www.
voltagemultipliers.com/pdf/High-Voltage-Op-Ampand-Linear-Regulator-App-Notes.pdf .
2) N. El-Sheimy, H. Y. Hou, X. J. Niu, IEEE Trans. Instrum. Meas. 57, 140–149 (2008).

Fig. 1. Design of the high-voltage stabilization circuit.
†

PID w/o RC Þlter
PID w/ RC Þlter
Present work

0.01

Digital controls
MCU

0.1

Condensed from Rev. Sci. Instrum. 91, 014702 (2020)
KEK Wako Nuclear Science Center
New Mexico State University
Institute for Basic Science- 126 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Eliminating mass-dependent inaccuracies in MRTOF-MS for the studyof RI using arbitrary reference masses

In high-precision mass spectrometry of radioactive
isotopes, mass dependent inaccuracies are one of the
major topics to be discussed, because the ionic mass
(mass-to-charge ratio) of the rare isotopes to be studied can be distant from that of the reference ionsused for calibration. In Penning-trap mass spectrometry, such eﬀects have been studied extensively inthe past using carbon cluster sources.1) For multireﬂection time-of-ﬂight (MRTOF) mass spectrometry
similar investigations are awaited, but are not completed yet. Other than in Penning traps, in electrostatic ion optics systems the trajectory of ions of equal
energy but diﬀerent mass is exactly the same, whichcomes from fundamental theorems. Following that,√ thedetected TOF of any ion is obtained by tD = α m/q,with the characteristic device constant α and m, q as
mass and charge. The mass can be calculated by useof a reference ion with m1 , q1 and TOF tD1 by:()2
m1 tD − t0
,
(1)
m=q
q1 tD1 − t0

relative mass deviation (mcalc − mreal )/mreal

M. Rosenbusch,∗1 P. Schury,∗1 M. Wada,∗1 S. Iimura,∗2,∗3 Y. Ito,∗4 and H. Wollnik∗5with t0 being the oﬀset time of the measurement (startof the TDC). However, mass-dependent inaccuracies
can come from the acceleration process of the ions,which has been investigated in a new theoretical framework.2) The acceleration process of ions out of an ion
trap happens with an electric ﬁeld that is switched onwith a transient in time with duration tT , and induces
a mass-dependent dynamic process. We have found asolution to include such a ﬁeld transition, and to calibrate masses far away from the reference mass despite
this eﬀect, while having only one reference ion species
available during the online measurement. To this end,
the system can be pre-calibrated once using two stable
ion species before the online
according√ measurement√
to the new equation tD = α m/q + β q/m having asecond device constant β. During the online measurement, only one of the two reference species serves again
as reference ion. Using a linear approximation of the⃗ =E⃗ max t , aacceleration ﬁeld during the increase E
tT
new equation has been found for the mass of the ions:
2

�(
)2
�
�
′
′
�
t �
tD1
tD1
β
t �
�
−  .
(2)
m = q D ′ +� D ′��
2α tD1
2α tD1
α
∗1
∗2
∗3
∗4
∗5

Wako Nuclear Science Center (WNSC), IPNS, KEK
RIKEN Nishina Center
Osaka University
Advanced Science Research Center, JAEA Ibaraki
Department of Chemistry and Biochemistry, New Mexico
State University- 127 -a)1.5e-031.0e-035.0e-04
0.0e+00-5.0e-04-1.0e-03-1.5e-03

single-ref. A = 85, uncorrected

3.0e-07b)

2.0e-071.0e-070.0e+00
single-ref. A = 85, corrected-1.0e-07
50

100

150

200

250

ionic mass / u

Fig. 1. Relative deviation from the real mass value (uponrecalculation of the mass from the TOF data of thereﬂectron simulation) as a function of the mass number,using a transition time of 100 ns. a): Recalculationof masses using the usual approach without correction
with mass A = 85 as reference ions. b): Recalculation
with correction using Eq. (2). Note the diﬀerent scales.

The times �t′D , �t′D1 , and �tD1 are reduced detection timesof the radioactive ion, the reference ion online, and thereference ion before the measurement, respectively. All
times are reduced according to �t′D = t′D − t2T −t0 , wheretT /2 is a new correction for the switching transition
emerging from the calculations. A simulation model
for a simple TOF mass spectrometer with short TOF of
only about 40 µs and a long switching time tT = 100 ns
has been written to show ampliﬁed eﬀects. The TOF
of ions has been simulated including dynamic acceleration, and over a broad mass range while assuming that
our reference ions have mass A = 85. The results using
the mass equation of the electrostatic problem and the
newly derived mass formula is shown in Fig. 1. It canbe seen that, in our constructed example, the impact ofsuch dynamic ion acceleration can be very signiﬁcant if
the switching is not fully considered. For MRTOF-MS,
however, this eﬀect is usually very small because of thefast switches (20 ns) and the very long TOF of 6 ms.
It will become important for measurements of superheavy nuclei with large mass distances of reference to
the SHE mass (depending on charge state), where theeﬀects can become signiﬁcant. The masses can thenbe accurately derived using the new correction.
References

1) A. Kellerbauer et al., Eur. Phys. J. D 22, 53 (2003).
2) M. Rosenbusch et al., Int. J. Mass Spectrom., underreview (2020).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

On-line mass measurement using multi-reflection time-of-flight mass
spectrograph (MRTOF-MS) at KISSJ. Y. Moon,∗1 T. Hashimoto,∗1 S. C. Jeong,∗2 M. Wada,∗2 P. Schury,∗2 Y. X. Watanabe,∗2 Y. Hirayama,∗2
Y. Ito,∗5 M. Rosenbusch,∗3 T. Niwase,∗4 H. Wollnik,∗6 and H. Miyatake∗2

Laser ON
1st. Laser OFF
1st/2nd Laser OFF
Laser/ICE OFF

35
30

(a)

25
20
15
(b)

10
5
0

6728100

140

6728200

6728300

6728400

6728500

Laser ON(c)

Laser OFF

120
100
(d)

80
60
40
20
0
6762900

6763000

6763100

6763200

6763300

6763400

6763500

TOF (ns)Fig. 1. Measured TOF spectra : 193 Os run (Upper) and194
Os run (Lower). See the text for details.
∗1
∗2

∗3
∗4
∗5
∗6

Institute for Basic Science, Rare Isotope Science Project
Wako Nuclear Science Center (WNSC), Institute of Parti- cle
and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)
RIKEN Nishina Center
Department of physics, Kyushu University
Japan Atomic Energy Agency
Department of Chem.&Bio.chem. New Mexico state university

Mass difference
Single reference (85Rb)

600

Single reference (Pt)400

M-MAME16 (keV/c2)

We report the ﬁrst online measurement using a newly
developed multi-reﬂection time-of-ﬂight mass spectrograph (MRTOF-MS), which recently achieved a mass
resolving power of, ∼120,000 in an oﬄine test. The detailed structure of the MRTOF-MS can be found in aprevious report.1) As a calibrant for the A ∼ 200 mass
region, 85 Rb ions were chosen because the 198 Pt ions extracted from the gas cell cooler buncher (GCCB), were
found more likely doubly charged.2) The Rb ions existing in the 133 Cs ion source were ﬁltered out by using therear linear Paul trap mass ﬁlter and transported withsigniﬁcant intensity. During the online experiment using a 198 Pt target of 12.5 mg/cm2 and 136 Xe beam of
10.75 MeV/nucleon, diﬀerent target-like isotopes were
produced in a multi-nucleon transfer reaction at KISS,3)
and among them, 194 Os ions were used to study the hyperﬁne structure.4) At KISS, by adjusting the laser frequency, speciﬁc ions are selectively ionized by irradiating the ionization lasers in two steps and transported

Double reference

200

y

ar
n
i
m

0

li
e
r
P

200
400
600
800

1000
194

Os

196

Os

198

Isotope

Ir

199

Ir

Fig. 2. Mass deviation from the AME2016 mass value. The
solid line denotes the uncertainties from the AME2016.

with almost 100% purity. However, in most of themeasurements, huge contaminants were observed, which
seemed irrelevant to the ionization laser. As an example, Fig. 1 demonstrates the contaminants observed in
the 193, 194 Os runs, in which (a) and (c) are 193 Pt and194
Pt ions, respectively, that survived from the elastic
events emitted from the production target. The othercontaminant near 194 Pt (d) is more likely a mixture of A
= 194 isotopes (Ir, Au, and Hg). The contaminant (b),6.5 micro-amu heavier than 193 Os, is not identiﬁed yet
but suﬃciently removed by the ion collection electrode(ICE). Fig. 2 demonstrates the accuracy and precision ofeach measurement of 194 Os (T1/2 = 6 y), 196 Os (T1/2 =30 m), 198 Ir (T1/2 = 8 s), and 199 Ir (T1/2 = 6 s). Three
diﬀerent methods implemented to derive their masses,
i.e., the single referencing method5) using 85 Rb ions or
Pt ions and the double referencing method,6) were compared there. It should be noted that the large discrepancy of 194 Os is more likely due to the contaminant included in the 194 Os position, as previously described.
The mass of 198 Ir has been directly measured for theﬁrst time, but it still needs more careful analysis.
References

1) J. Y. Moon et al., RIKEN Accel. Prog. Rep. 52, 138(2019).
2) P. Schury et al., in this report.
3) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res. B
353, 4 (2015).
4) Y. Hirayama et al., in this report.
5) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B
335, 39 (2014).
6) F. Wienholtz et al., Nature 498, 346 (2013).

- 128 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Collinear laser spectroscopy of Ba+ in 6s 2 S1/2 -6p 2 P3/2 transition
Y. Sasaki,∗1,∗2 M. Tajima,∗1 A. Takamine,∗1 H. Iimura,∗1,∗3 M. Wada,∗4 Y. Matsuo,∗1,∗2 and H. Ueno∗1
The nuclear electromagnetic properties in nuclear
ground states and long-life isomeric states for a wide
range of nuclides have been determined using collinear
laser spectroscopy (CLS).1) We are developing a CLS
apparatus for the slow RI beams that will be provided
from the SLOWRI facility2) in the near future, with thegoal of realizing CLS for RIs that are diﬃcult to obtainthrough the isotope separation on-line (ISOL) method.
We have started oﬀ-line CLS test. As a ﬁrst step, weselected stable Ba+ isotope ions since their high intensity ion beams can be produced with a compact surface
ionization source.
This report describes the oﬀ-line CLS experiment for
the transition from the ground state 6s 2 S1/2 to theexcited state 6p 2 P3/2 . Tajima et al. report on the
CLS test for the transition from 4d 2 D5/2 to 6p 2 P3/2
in this progress report.3) The excitation wavelength forthe 6s 2 S1/2 → 6p 2 P3/2 transition for Ba+ is 455 nm.
We built an external cavity diode laser (ECDL), which
was assembled with an anti-reﬂection-coated laser diodeNDBA116T (peak wavelength range: 450 to 470 nm;
manufactured by Nichia Corporation) and a 2400/mm
holographic grating (Thorlabs GH13-24V) in a Littrow
conﬁguration. The wavelength of the ECDL was locked
to a desired wavelength using a feedback system of ahigh-precision wavemeter (HighFiness WS-U-10). The
resulting time variation of the center frequency of thelaser was narrowed to 4 MHz in full width at half maximum (Fig. 1).
The CLS test was performed using a home-built
ECDL. Figure 2 shows a schematic of our CLS apparatus. Barium ions generated from the surface ionizer
were accelerated by a high voltage of 10 to 20 keV. The
accelerated ions were transported to an observation region after mass separation by a mass analyzing magnet.

Fig. 1. Frequency locking result for our ECDL.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Department of Advanced Science, Hosei University
JAEA
Wako Nuclear Science Center (WNSC), KEK

Fig. 2. Schematic diagram of our collinear laser spectroscopy
apparatus.

Fig. 3. Collinear laser spectroscopy spectra for 136–138 Ba+ .

A series of electrodes to control the Doppler shift wasplaced around the observation region. Laser-induced
ﬂuorescence (LIF) from the ions was collected in a photomultiplier tube in front of the electrodes, as shownin Fig. 2. We observed resonance spectra while scanning the voltage of the electrodes to control the Doppler
shift of the ions, instead of scanning the laser frequency.
Figure 3 shows the observed spectra for 136, 137, 138 Ba+ .
At this time, the ions were accelerated to 10.51 keV,
the laser frequency was locked to 658.372682 THz, andthe laser power was 0.1 mW. The beam intensities were
200 pA, 350 pA, and 1.4 nA for 136 Ba+ , 137 Ba+ , and138
Ba+ , respectively. We successfully observed ﬁve resonance peaks for the transition between the hyperﬁnesublevels of 137 Ba+ , and only the peaks for the 6s 2 S1/2
state (F = 1) → 6p 2 P3/2 state (F = 0, 1) transition
were not resolved, because the spacing is 32 MHz at
most.
We continue systematic measurements under various
experimental conditions such as diﬀerent laser powers,
acceleration voltages, and laser light path alignments
for resolution improvement. We will also improve thesensitivity using a coincidence method,4) aiming at the
spectroscopy for low-yield nuclei obtained at online experiments.
References

1) P. Campbell et al., Prog. Part. Nucl. Phys. 86, 127 (2016).
2) M. Wada, Nucl. Instrum. Methods Phys. Res. B 317, 450(2013).
3) M. Tajima et al., in this report.
4) D. A. Eastham et al., Opt. Commun. 60, 293 (1986).

- 129 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

LIF observation of Rb atoms in superfluid heliumby picosecond pulsed laser pumping
Y. Takeuchi,∗1,∗2 H. Kuramochi,∗3 K. Imamura,∗2 A. Takamine,∗2 M. Doi,∗1,∗2 T. Yamamoto,∗1,∗2 Y. Matsuo,∗1,∗2
Y. Zempo,∗4 T. Tahara,∗3 and H. Ueno∗2←PMT

Our research group has been developing a laser specmonochromator
troscopic method named OROCHI. The system uses su100 mm
100 mmperﬂuid helium (He II) as a trapping medium of atoms,
100 mmlens
and the interaction between the immersed atoms and the（f＝100mm)
LIF
surrounding helium atoms leads to a unique property of
200 mmthe spectroscopic environment. In particular, the Stokes Dissociation Laser
200 mmshift of the immersed atoms is important for understand- (Femtosecond Ti:Sa)
Excitation Laser(Picosecond Ti:Sa)
ing the dynamics of He II. In this study, we focus on the
Cryostat“atomic bubble” that causes the Stokes shift.
When atoms are introduced into He II, the surroundAblation Laser (Nd:YAG)
Quartz celling helium atoms are pushed out by the exchange (Pauli)
repulsion force.1) The resulting vacuum region is called
Fig. 2. Experimental setup of LIF detection.
an atomic bubble. When the shape of the outer electron
orbit of the atom changes owing to a state transition
such as excitation or absorption, the deformation of the sured by observing the time dependence of the emission
atomic bubble follows. This cycle is repeated at each wavelength.
excitation (Fig. 1).
For the observation, we plan to use a time-correlated
The absorption and emission occur within about single photon counting (TCSPC) system with a detec10−15 s, while it is estimated that the deformation of the tor of high time resolution. The TCSPC records the
bubble occurs on a timescale of a few picoseconds.1) How- time between the input of the excitation pulse laser sigever, this relaxation time has not been directly measured nal and the detection of the laser-induced ﬂuorescencein the picosecond time scale so far. To clarify the dynam- (LIF) photon to obtain the time dependence of the LIF
ics of the atomic bubble system, we combined the laser intensity. The typical time resolution of the system isspectroscopic technique in He II and an ultrafast laser 80 ps.
spectroscopic technique.2) In this research, we started
In this method, the pulse width of the excitation laser
with Rb as a target atom because its characteristics in must be shorter than the relaxation time. Therefore,
He II has been well studied.3,4) We here describe the cur- a picosecond mode-locked Ti: sapphire laser was introrent status of preparation for the ﬁrst measurement of duced. The typical pulse width of the laser is 1.6 ps.
the relaxation time.
Since the LIF of atoms in He II with ultrashort pulse
The wavelengths of atomic transitions in He II shift lasers has not been observed, we conducted a laser perbetween absorption and emission owing to this defor- formance evaluation experiment.
mation cycle.3) In the excited state, a part of atoms in
The observation was performed using the picosecond
the observation area are expected to emit photons dur- laser (laser power: 103 mW, repetition rate: 80 MHz)ing the deformation process before the atomic bubble and an oﬄine experiment setup and a laser sputteringreaches its potential minimum of the excited state. Be- method to introduce atoms. We used a monochromatorcause the change of the emission wavelength corresponds and a photomultiplier tube for the ﬂuorescence detection
to the degree of deformation, the relaxation time is mea- system. First, the LIF was measured by a wavelength
sweep of the excitation laser. We obtained a spectrum
Deformthat showed a peak in the ﬂuorescence intensity at a laser
Electron crowd(Relaxation)
wavelength of approximately 778 nm. This wavelength(p orbital)corresponds to the D1 excitation of Rb atoms in He II.
Next, by ﬁxing the laser wavelength ﬁxed at the peakin He II
Absorption
Emission position, a wavelength sweep of the monochromator was
performed. We observed an LIF spectrum centered atDeform
794 nm, which is the D1 emission wavelength in He II.
Electron crowd(Relaxation)(s orbital)
In summary, we successfully observed the LIF of atoms
in He II using the picosecond laser. We are planning toconduct an experiment of the relaxation time measurement by the TCSPC system.
Fig. 1. Deformation cycle of an atomic bubble.
∗1
∗2
∗3
∗4

Department of Advanced Sciences, Hosei University
RIKEN Nishina Center
Molecular Spectroscopy Laboratory, RIKEN
Department of Computer and Information Science, Hosei University

References

1) B. Tabbert et al., J. Low Temp. Phys. 109, 653 (1997).
2) D. Mandal et al., Chem. Phys. Lett. 359, 77 (2002).
3) Y. Takahashi et al., Phys. Rev. Lett. 71, 1035 (1993).
4) T. Furukawa et al., Hyperfine Interact. 196, 191 (2010).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Measurement of stopping-position width of highly energetic Rb ion
beams in liquid nitrogen
M. Nishimura,∗1,∗2 K. Imamura,∗2 A. Takamine,∗2 K. Tsubura,∗1,∗2 A. Gladkov,∗2 Y. Takeuchi,∗1,∗2 M. Doi,∗1,∗2
T. Yamamoto,∗1,∗2 M. Tajima,∗2 T. Asakawa,∗1,∗2 Y. Sasaki,∗1,∗2 K. Doi,∗1,∗2 K. Kawata,∗2,∗3 H. Nishibata,∗2,∗4
Y. Ichikawa,∗2 H. Ueno,∗2 and Y. Matsuo∗1,∗2
We are developing a laser spectroscopy technique
named optical RI-atom observation in conduced helium
as ion catcher (OROCH) for the study of nuclear properties of unstable nuclei. In this method, highly energetic ion beams are stopped in superﬂuid helium (HeII) and neutralized, following which atoms are subjected
to in-situ laser spectroscopy. The combination of optical pumping and the laser radiofrequency (RF) of microwave (MW) double-resonance methods enables us todetermine the Zeeman and hyperﬁne splittings of atoms,
from which the nuclear spin and moment are deduced.
The method is promising particularly for low-yield nuclei
because the stopping eﬃciency of He II is nearly 100%.
We have successfully observed laser-induced ﬂuorescence(LIF) from 85 Rb atoms of about 200 pps injected into He
II as a 66 AMeV beam in the RIKEN RIPS beamline.1)
However, the above energy beams could just reach thecenter of the optical cryostat after travelling for several
millimeters in He II. In order to apply this method toheavier elements such as Ag, Cs, and Au, a beamline ofhigher energy is necessary to transport beams to the LIF
observation region (ϕ2 mm × 5 mm).
As the ﬁrst step, we plan to apply this method toFig. 1. Schematic of (a) the pre-cryo and (b) the cryostat
chambers.
∗1
∗2
∗3
∗4

Department of Advanced Sciences, Hosei University
RIKEN Nishina Center
Center for Nuclear Study(CNS), Tokyo University
Department of Physics, Kyusyu University

Fig. 2. Diﬀerential PL2 counts as a function of the Al degrader thickness.

radioactive Rb isotopes provided by the HIMAC SB2
beamline at NIRS. To verify the feasibility of an online
experiment, we investigated beam yields and beam proﬁle using a 84 Rb beam produced from a primary 84 Kr
beam on a Be target of 350 AMeV. We observed photons from plastic scintillators to estimate the number of84
Rb ions stopped in the LIF observation region. Liquid nitrogen was used as a stopper instead of superﬂuid
helium in this experiment.
Figure 1 shows the schematics of the “pre-cryo” andcryostat chambers where two plastic scintillators PL1and PL2 are placed. Details of the apparatus andmeasurement method are described elsewhere2) in thisprogress report.
The result of the PL1 counts acquired to investigate
the transverse beam proﬁle is reported in Ref. 2). In order to measure the longitudinal stopping position of thebeam, we counted the PL2 photons as a function of the
thickness of aluminum energy degrader. The degrader
thickness was changed in steps of 50 µm. Figure 2 shows
the diﬀerential counts between neighboring thicknesses,
which correspond to the number of stopped ions. Thatis, the diﬀerential counts indicate the range distribution
for the beam if the stopper material is regarded as aluminum. We found that the optimal degrader thickness
was ∼750 µm. The beam was stopped within a longitudinal width of 0.3 mm in aluminum. From this result,
we roughly determined that the beams were stopped ina width of 1 mm in liquid nitrogen. If we convert thisvalue to the stopping-position width in He II, the beams
are estimated to be stopped in a width of 6 mm, considering the material density of He II. Further analysis
to estimate the 84 Rb atom yields in the LIF observation
region combined with the transverse beam proﬁle is inprogress.
References

1) K. Imamura et al., Appl. Phys. Express 12, 016502 (2019).
2) K. Tsubura et al., in this report.

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Investigation of the secondary rubidium beam profile at HIMAC
towards laser spectroscopy in an optical cryostat
K. Tsubura,∗1,∗2 K. Imamura,∗2 A. Takamine,∗2 M. Nishimura,∗1,∗2 A. Gladkov,∗2 Y. Takeuchi,∗1,∗2
M. Doi,∗1,∗2 T. Yamamoto,∗1,∗2 M. Tajima,∗2 T. Asakawa,∗1,∗2 Y. Sasaki,∗1,∗2 K. Doi,∗1,∗2 K. Kawata,∗2,∗3
H. Nishibata,∗2,∗4 Y. Ichikawa,∗2 H. Ueno,∗2 and Y. Matsuo∗1,∗2
We are developing a laser spectroscopy technique
named Optical RI-atom Observation in Condensed Helium as Ion-catcher (OROCHI) for the study of nuclear
spins and moments. In the OROCHI experiment, wecatch highly energetic ion beams in superfluid helium(He II) in our cryostat to neutralize them and conduct
in-situ laser spectroscopy. We irradiate the neutralized
atoms with circularly polarized laser light to produce
spin polarization and measure the atomic Zeeman andhyperfine splitting of the atoms using the laser-radiofrequency and laser-microwave (mw) double resonancemethod.
In the previous online experiment,1) our group observed the laser-rf double resonance spectra for 84–87 Rb
ion beams. It was reported that the atoms in superfluid
helium shows a hyperfine structure constant slightly
lager than that of a free atom by ∼1%.2,3) Now, basedon our interest in the hyperfine anomalies of the atoms
in superfluid helium, we plan to measure the hyperfine
splitting of the radioactive Rb, Ag, Cs, and Au isotopes, to which this method has not been applied.
We plan to apply this method to radioactive Rb
isotopes provided by the HIMAC SB2 beam line at
NIRS in FY 2020. As a prerequisite online experiment, we measured the beam yields of a 84 Rb beam
produced in proton pickup reactions by a 84 Kr beamof 350 A MeV on a Be target of 12 mm thickness toinvestigate the beam profile of 84 Rb ions stopped ina laser-induced fluorescence (LIF) observation region(ϕ2 mm × 5 mm).
The beam yields were counted with two plastic scintillation counters. One plastic scintillator (“PL1”:
30 mm square × 0.1 mm thickness) was placed ina chamber, which we call the “pre-cryo chamber,”in front of the cryostat. Another plastic scintillator(“PL2”: 10 mm square × 0.5 mm thickness) was placedat the center of the cryostat. A variable energy degrader system was placed upstream of PL1, and oneof the collimators having various diameters can be set
just upstream of PL1 in the pre-cryo chamber. A figure for the setup and the role of PL2 is described in thereport by M. Nishimura et al.4) in this progress report.
We measured the beam yields using PL1 as a function of the collimator diameter in order to investigate
the transverse beam profile. The coincidence pulses
∗1
∗2
∗3
∗4

Fig. 1. Collimator diameter dependence of the yield of thesecondary beam.

of two photomultipliers mounted at the left and rightsides of PL1 were counted by a multichannel scaler(Techno AP APG7400A USB-MCA4) with a dead timeof 1.5 µs. Figure 1 shows the collimator diameter dependence of PL1 counts. The primary beam intensity
was 2×108 particles per spill (the repetition cycle of thebeam spill was 3.3 s) for this measurement. Because
the beam purity was ∼40%, which was evaluated fromthe particle identification, we found that 84 Rb beams
of 3.8 × 104 particles per spill were provided from the
HIMAC SB2 line at the full primary beam intensityof 5.9 × 108 particles per spill with a dead-time correction. This value agrees with a LISE++ calculation
result. Currently, we are carefully analyzing the dataand evaluating the beam profiles of 84 Rb and impurity
82
Kr, assuming the beam profiles follow a Gaussian
distribution.
In summary, we evaluated the secondary beam yield
variations by changing the collimator size to investigate the transverse profile of the beam. Combinedwith the results for the longitudinal distribution of the
stopped atoms in the cryostat using PL2 counts,4) the
estimation of the yield and profile of 84 Rb atoms in
the LIF observation region is in progress. We will verify the feasibility of the hyperfine structure constantmeasurements for various Rb and Ag isotopes at the
HIMAC SB2 beam line.
References
1) X. F. Yang et al., Phys. Rev. A 90, 052516 (2014).
2) Y. Takahashi et al., Z. Phys. B 98, 391 (1995).
3) T. Furukawa, Ph.D. thesis, Osaka University (2007).
4) M. Nishimura et al., in this report.

Department of advanced science, Hosei University
RIKEN Nishina Center
CNS, University of Tokyo
Department of Physics, Kyushu University- 132 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Degrader system for ZD-MRTOF
J. J. Liu,∗1,∗2 S. Chen,∗1,∗2 S. Iimura,∗3 M. Wada,∗2 H. Ishiyama,∗3 A. Takemaine,∗3 M. Rosenbusch,∗2
D. S. Hou,∗4 and P. Schury∗2

∗1
∗2
∗3
∗4

Energy loss in ion chamber (a.u.)(a) ∆E - ∆E at a degrader angle of 20°
1400

1350

1300
81

Ga

1250
80

Zn

1200
500

550

600
650
Energy loss in Si (a.u)

700

750

(b)
b) Energy loss in Si vs. degrader an
2000
Energy loss in Si (a.u)

After the successful experience with gas-cell techniques and the multi-reﬂection time-of-ﬂight mass
spectrograph (MRTOF-MS) at SLOWRI and GARISII, parasite experiments for commissioning the cryogenic He gas cell and MRTOF-MS using the ZeroDegree spectrometer have been proposed. A gutter RF
carpet gas cell will be installed at the downstreamside of F11 to stop heavy ions and extract them tothe MRTOF-MS. Since the maximum stopping powerof the gas cell is ∼0.7 MeV/nucleon1) ions dumped
from ZeroDegree that have an energy higher than
100 MeV/nucleon need to be slowed down before entering the gas cell. A degrader system will be installed.
Additionally, as the commissioning will be run symbiotically with other ZeroDegree experiments, an independent data acquisition (DAQ) system for particle
identiﬁcation (PID) should be developed.
A movable ﬂat Pb-glass degrader with a thickness of
7.1 mm was combined with a step motor rotating in
the vertical direction from 0◦ to 90◦ , which is mounted
in front of the gas-cell window. The step motor hasa high resolution of 0.0072◦ per step enabling the ﬁnetuning of the eﬀective degrader thickness. The maximum eﬀective thickness of the degrader is 10.04 mm
when the degrader rotates to 45◦ , while there is nodegrader at 90◦ . An online PID DAQ system withshared beam signals from ZeroDegree is developed independently for the BigRIPS DAQ, which will not bein conﬂict to other experiments. The PID could be performed by the ∆E-∆E method using a multi-samping
ion chamber at F11 and Si detectors. Moreover, the∆E-TOF-Bρ method for PID could be applied using
the multi-samping ion chamber at F11, time of ﬂight
from F8 to F11 and F10 PPAC position information.
With the selection of speciﬁed ions, the degarder angle
can be optimized by measuring beam energy loss in the
Si array. After ﬁxing the angle of the degarder, the Si
array will be removed and ions will be transported to
the gas-cell.
The degrader system has been tested in an online
experiment. A 238 U primary beam with an energyof 345 MeV/nucleon was incident on a 4-mm thick9
Be target. Fragmentation around 80 Zn was produced
and selected by BigRIPS and ZeroDegree spectrometers, where a wedge-shaped degrader at F10 was utilized so as to mono-energetically focus particles on F11
by adopting the LAA-monoionic optical mode. The
PID has been performed by the ∆E-∆E, as shown
Department of Physics, the University of Hong Kong
Wako Nuclear Science Center,KEK
RIKEN Nishina Center
Institute of Modern Physics- 133 -

Si array

1500

81

Ga

1000

gas cellθPb-glass

500

0
0

20

40
60
Degrader angle θ (°)

80

Fig. 1. (a) Particle identification using the ∆E-∆E methodby a multi-sampling ion chamber at F11 and Si detector;(b) energy loss in the Si detector as a function of thedegrader angle

in Fig. 1(a), with a reasonable resolution. By scanningthe degrader angle θ from 0◦ to 90◦ and gating on 81 Ga,
the energy loss in Si as a function θ was obtained asshown in Fig. 1(b). By ﬁne tuning of θ from 39◦ to
40◦ , 81 Ga was expected to be caught by the gas cell.
This result is consistent with LISE++ calculation.
A real-time PID trigger is under construction within
the PID DAQ system, and it can be possible to stopa single ion in the gas cell. With selected particle information from the DAQ, a pulse will be generated toturn oﬀ the DC ﬁeld in the gas cell for a half life of
the selected ion. In such a condition, the β-delayed
neutron emission probability of the ion can be determined by counting daughter nuclei distinguished using
MRTOF-MS.
Reference

1) M. Wada et al., Nucl. Instrum. Methods Phys. Res. B
204, 570–581 (2003)

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

First test of graphenic carbon vacuum windows with heavy ionsS. Purushothaman,∗1 H. Haba,∗2 E. Haettner,∗1 S. Ishikawa,∗3 K. Itahashi,∗2 S. Y. Matsumoto,∗2,∗4
Y. Miyake,∗2 A. Sakaue,∗4 R. Sekiya,∗4 Y. K. Tanaka,∗1,∗5 and M. Tomut∗6
Currently, one of the main concerns in experiments
involving high-luminosity hadron beams is the limitations imposed by the materials directly interactingwith the beam. Beam windows are essential components in every accelerator and many experimental systems, and they experience enhanced radiation damage,high operation temperatures, and high thermal andtransient stresses, adding to pressure diﬀerences between the beam vacuum and atmosphere. Graphenic
carbon membranes are an excellent replacement for
conventionally used window materials such as steel,beryllium, aluminum, or Inconel alloys because of their
low atomic number and excellent thermomechanicalproperties. The excellent mechanical properties andmolecular impermeability of suspended graphenic carbon membranes1,2) make them an ideal vacuum window material with an extremely low window thickness
that meets the mechanical stability requirements.
Due to the ultrahigh electron transmissivity in awide electron energy range, high electrical conductivity, and high chemical stability of suspended graphenic
carbon membranes, their use as a vacuum window material is currently being explored, and they are being
implemented in ﬁelds such as electron microscopy and
X-ray photoelectron spectroscopy. In a recent development, a novel x-ray transmission window based onpolycrystalline graphene or graphenic carbon (GC) has
been developed1,2) as a replacement for the beryllium
transmission windows in X-ray detectors. A maximum
burst pressure of about 0.5–0.6 MPa at a window thickness of 1 µm and a diameter of 7.5 mm has been reported in Ref. 2).
The work outlined here aims intended to explore
the outstanding mechanical properties demonstrated
by the above-mentioned GC X-ray window within thecontext of hadron beams. As the ﬁrst step, diﬀerent aspects of irradiation-induced damage in the material were investigated in detail using 200 particle nA,
5 MeV/nucleon 20 Ne ion beam from the AVF accelerator at RIKEN. GC samples were placed at the E7Btarget position and irradiated. The total dose of each
irradiation procedure was quantiﬁed by measuring thebeam current with an accuracy of 5%. A collimator slitof a 3 mm width was used to limit the beam size on thesamples. A Faraday cup downstream of the collimator
was used to quantify the ﬂuence.
∗1
∗2
∗3
∗4
∗5
∗6

GSI Helmholtzzentrum für Schwerionenforschung
RIKEN Nishina Center
Tohoku University
Kyoto University
RIKEN CPR
University of Münster

Fig. 1. (a) Non-irradiated sample. Foil irradiated at
200 particle nA for (b) 1 h 51 min at a total fluenceof 9.7 × 1016 particles/cm2 , (c) 3 h 30 min at a total
fluence of 2.1 × 1017 particles/cm2 , and (d) 10 h at a
total fluence of 2.1 × 1017 particles/cm2 . Although thebeam was collimated using a 3 mm collimator slit, theobtained beam spot was “comma” shaped with a nonuniform intensity distribution. This is reflected in the
shape of the beam-induced compaction (marked with
red dotted curves).

Five graphenic carbon samples of thickness 1 µm anddiameter 7.5 mm were irradiated for diﬀerent time intervals (ﬂuences ranging from 9.7 × 1016 particles/cm2
to 9.7 × 1017 particles/cm2 ) to study the evolution ofirradiation-induced structural change.
The foil could mechanically withstand a 200 particle nA DC beam up to 10 h. A detailed investigation of
the eﬀects of irradiation-induced damage in the material is ongoing at the University of Münster and at GSI
using Raman spectroscopy, scanning and transmission
electron microscopy, and nanoindentation.
The next step will be to evaluate the performance
under pressure during the irradiation under a diﬀerential helium pressure of 0.2 MPa across the membranes
while monitoring the evolution of helium leakage. This
will check the feasibility of the GC vacuum window as
a candidate for hadronic ion beams.
References
1) S. Huebner et al., MRS Adv. 1.20, 1441 (2016).
2) S. Huebner et al., IEEE Trans. Nucl. Sci. 62.2, 588(2015).

- 134 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Heavy-ion irradiation test of radiochromic films
T. Kambara,∗1 A. Yoshida,∗1 Y. Hayashi,∗1 K. Ishii,∗1 and T. Abe∗1
The heavy-ion irradiation of biological or industrial
samples requires the dose-distribution measurement ofa beam spot 5–10 cm in diameter. A radiochromic
ﬁlm changes its color according to the absorbed doseof ionizing radiation and enables two-dimensional highresolution dose-distribution measurements. It is easy tohandle and portable, and a personal computer can capture its image with an inexpensive and common image
scanner and convert the numerical data of the image
to optical density (OD) as a function of the absorbed
dose.1) Radiochromic ﬁlms are widely used in radiotherapy for dosimetry of high-energy photons.
In order to assess the usefulness of radiochromic ﬁlms
in our high-energy heavy-ion irradiation, we tested two
types of ﬁlms, GAFCHROMICTM HD-V2 for a higher
dose and EBT-3 for a lower dose,2) using heavy ionswith a wide range of linear energy transfer (LET). The
irradiation targets were 4 cm × 5 cm rectangular segments of vendor-supplied 25 cm × 20 cm sheets of theﬁlms. The HV-D2 targets were irradiated by C ionswith LETs of 22.5 and 179 keV/µm, Ar ions with LETsof 184 and 673 keV/µm, and Fe ions with LETs of 637
and 1061 keV/µm with dose ranging from 1 to 400 Gy,
and the EBT-3 targets were irradiated by C ions with
LET of 22.5 keV/µm, Ar ions with LET of 184 keV/µm,
and Fe ions with LET of 637 keV/µm with dose ranging
from 0.2 to 10 Gy.
The targets were irradiated at the E5B beamline of
the RIKEN Ring Cyclotron where the LET was adjusted
by Al-plate degraders.3) The beam was collimated by a
20-mm-diameter aperture on a 10-mm-thick brass plate
about 153 mm upstream of the target.
Before and after the irradiation, the target wasscanned by an image scanner and converted to a 24-bit
75-dpi bitmap ﬁle. The numerical values of the three
primary colors (RGB) of each pixel were converted to
OD values following the procedure described in Ref. 1).
Although each of the RBG colors can yield OD distributions, we show in the following the results for green,
which is the most sensitive.

Fig. 1. Images, the corresponding OD distributions and onedimensional vertical distributions through the center ofﬁlms irradiated by (a) C ions after an 18.6-mm-thick degrader and (b) Ar ions without a degrader.

∗1

Fig. 2. OD of the ﬁlms irradiated by heavy ions with diﬀerent
LETs as functions of the absorbed dose.

Figure 1 shows examples of images of the irradiatedtargets, the corresponding two-dimensional OD distributions, and its one-dimensional distribution along a vertical line through the center: (a) an HD-V2 ﬁlm irradiatedby 200 Gy of 179-keV/µm C ions and (b) an EBT-3 ﬁlm
irradiated by 10 Gy of 184-keV/µm Ar ions. The image in (a) is blurred since the C ions passed through an
18.6-mm-thick degrader before the target. The image in(b) is clear; its OD distribution is ﬂat in the beam spotand drops sharply within about 1 mm at the edge since
the Ar ions did not pass through a degrader.
We obtained the net OD distribution of a target as thediﬀerence between the distributions before and after theirradiation, and we took the OD value at the center ofthe beam spot. Figure 2 compares the dose dependenceof the net OD value for diﬀerent irradiation conditions
and ﬁlms.
The dose dependence of OD has a common feature: it
ﬁrst increases linearly and ﬁnally saturates above 200 Gy
for HD-V2, but it does not saturate up to 10 Gy for
EBT-3. It is higher for lighter ions and lower LETs but
does not strongly depend on the ion and LET, remaining
within ±30% overall, although the atomic number of theions is diﬀerent by more than 4 and the LET is diﬀerent
by nearly 50.
As a whole, the radiochromic ﬁlms can be useful forvarious heavy ions with a wide range of LETs to evaluate doses between 0.2 and 200 Gy and to measure thetwo-dimensional dose distribution with a spatial resolution of about 1 mm. The ﬁlms may also be useful forthe comparison of irradiation dose between distant irradiation facilities since they are easily transported andtreated.
References

1) T. Agematsu, H. Hanaya, T. Kojima, Radioisotopes 57,
87 (2008) (Japanese).
2) http://www.gafchromic.com/ .
3) H. Ryuto, T. Abe, N. Fukunishi, M. Kase, Y. Yano,
J. Biomed, Nanotechnol. 2, 1 (2006).

RIKEN Nishina Center- 135 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Computing and network environment at the RIKEN Nishina Center
T. Ichihara,∗1 Y. Watanabe,∗1 and H. Baba∗1
We are operating Linux cluster systems1) at the
RIKEN Nishina Center (RNC).
Figure 1 shows the current configuration of theLinux servers at the RNC. The host RIBF.RIKEN.JP
is used as the mail server, the NFS server of the user
home directory, and the NIS master server. This is
the core server for the RIBF Linux cluster. A new
ssh login server RIBF02.RIKEN.JP with the CentOS
8.0 operating system (OS) was installed in November
2019.
For the mailing list service, we have been using
the Majordomo2) mailing list software at the host
RIBF.RIKEN.JP for a long time. Since the maintenance of Majordomo was terminated several years
ago, we have changed the mailing list software to
Mailman.3) Mailman has several functions addressing Domain-based Message Authentication Reporting

















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and Conformance (DMARC)4) which has been introduced recently at the Federal Agencies5) in US together with Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM).
The hosts RIBFSMTP1/2 are the mail gateways,
which are used for tagging spam mails and isolating virus-infected mails. The latest version of Sophos
Email Protection-Advanced (PMX 6.4.8) has been installed. Figure 2 shows the mail trends in 2019. Approximately 50% of the incoming mails were blocked
by the PMX ip-blocker.
The host RIBFUSER has been used for the RIBF
User Group registration and election of Users Executive Committee (UEC) members. Since twelve years
had passed since the installation of this server, we replaced it with a new server, HP-DL20G9 with SL7.4
OS, in January 2019.
The host RIBFWEB1 has been used as the Web
server in RNC. Because seven years had passed since
the installation of this server, we replaced it with a newserver, HP-DL20G10 with CentOS 8.0 OS, in November 2019. With a virtual host function of the Apache
http server, eight multi-host Web contents have been
served at the server simultaneously
An anonymous ftp server, FTP.RIKEN.JP, is managed and operated at the RNC. Major Linux distributions, including Scientific Linux, Ubuntu, and CentOS,
are mirrored daily for the convenience of their users
and for facilitating high-speed access.
References

1) T. Ichihara et al., RIKEN Accel. Prog. Rep. 52, 159(2019).
2) http://old.greatcircle.com/majordomo/ .
3) https://www.list.org/ .
4) https://en.wikipedia.org/wiki/DMARC .
5) https://cyber.dhs.gov/bod/18-01/ .

Fig. 1. Configuration of the RIBF Linux cluster.

∗1

Fig. 2. Mail trends: message categories in 2019.

RIKEN Nishina Center- 136 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

CCJ operations in 2019
S. Yokkaichi,∗1 H. En’yo,∗1 T. Ichihara,∗1 W. Nakai,∗1 and Y. Watanabe∗1
Table 1. Number of malfunctioning HDDs in HP servers
during 2011–2019.

Overview
The RIKEN Computing Center in Japan (CCJ)1)
commenced operations in June 2000 as the largest oﬀsite computing center for the PHENIX2) experimentbeing conducted at RHIC. Since then, CCJ has been
providing numerous services as a regional computing
center in Asia. We have transferred several hundred
TBs of raw data ﬁles and nDST a) ﬁles from the RHIC
Computing Facility (RCF)3) to CCJ.
Many analysis and simulation projects are being
conducted at CCJ, which are listed on the web page
http://ccjsun.riken.go.jp/ccj/proposals/. As of December 2019, CCJ has contributed to 43 published papers and 44 doctoral theses.

for the RHICf group8) and two servers for the J-PARC
E16 group,9) in order to keep their dedicated compilation and library environments along with some data.
Three 10-KVA UPSs are operated as power supply forthese CCJ nodes, should be replaced in 2020.

Computing hardware and software

Joint operation with ACCC/HOKUSAI

The network conﬁguration and the computing hardware (nodes) and software (OS, batch queuing systems, database engine, etc.) are almost the same as
described in the previous APR.1) We have two login
servers, one main server (users’ home directory, NIS,
DNS, and NTP), and two disk servers the disk sizesof which are 13 and 26 TB. The main server has anexternal SAS RAID (21 TB) for the home and work
regions of users as well as system usage. Moreover, theserver has a RAID with built-in disks (13 TB) that canbe used temporarily by users and the system.
We operate 26 computing nodes, of which 16 nodes
were purchased in Mar. 2009 and 10 nodes were purchased in Mar. 2011. Thus, in total, 368 (= 8 × 16
nodes + 24 × 10 nodes ) jobs can be processed simultaneously by these computing nodes using a batch queuing system, LSF 9.1.3.4) The LSF license contract in
CCJ is for 358 in total in JFY 2019, after the transferof 80 licenses from the RIBF cluster. Table 1 lists thenumber of malfunctioning SATA or SAS disks in the
HP servers, namely, computing nodes and NFS/AFS
servers.
One database (postgreSQL5) ) server and one AFS6)
server are operated in order to share the PHENIX computing environment. It should be noted that only theSL57) environment is shared by the computing nodes,
which have approximately 0.9 TB of library ﬁles. We
started two new data-transfer servers, which have a
10 G Ethernet I/F and 12 TB SATA RAID with builtin disks. Data transfer of the order of 100 TB from
J-PARC will start in 2020 and also from BNL in the
future. In addition, we operate two dedicated servers

CCJ and the RIKEN Integrated Cluster of Clusters(RICC) have been jointly operated since July 2009. In
April 2015, a new system named “HOKUSAI Greatwave” was launched by RIKEN ACCC,10) and the joint
operation with CCJ continued, with the inclusion ofa new hierarchical archive system in which approximately 900 TB of CCJ data are stored. As of Nov.
2019, 886 TB is used, with the inclusion of 749 TB of
PHENIX oﬃcial data, 25 TB of KEK/J-PARC data,
3 TB of RHICf data, and 109 TB of user-level archive
data. Subsequently, the “HOKUSAI BigWaterFall” IA
cluster, which has 840 nodes/33600 CPU cores, waslaunched in 2017 by ACCC. CCJ has not started touse the cluster, because it lacks support for NFS toshare the computing environment of PHENIX, unlike
RICC. In autumn in 2020, ACCC will start a charging
system to users for thier usage of CPU-time and storage capacity. Thus we are discussing the optimal ratioof purchasing new machines to paying to ACCC.

∗1a)

RIKEN Nishina Centerterm for a type of summary data files in PHENIX- 137 -

Type(Size) total
192
SATA (2 TB) 120
SATA (4 TB)
10
SAS (146 GB)
38
SAS (300 GB)
26
SATA (1 TB)

19 18 17 16 15 14 13 12 11
8 16 18 8 14 11 16 20 9
10 2 10 2 10 0 2 5 4
0 0
6 3 1 5 3 2 0 1 1
2 0 1 0 1 1 0 0 1

References
1) S. Yokkaichi et al., RIKEN Accel. Prog. Rep. 51, 188(2018).
2) http://www.phenix.bnl.gov/ .
3) https://www.racf.bnl.gov/ .
4) https://www.ibm.com/support/knowledgecenter/en/
SSETD4_9.1.3/lsf_welcome.html .
5) http://www.postgresql.org/ .
6) http://www.openafs.org/ .
7) http://www.scientificlinux.org/ .
8) Y. Itow et al., arXiv:1409.4860 (Proposal).
9) S. Yokkaichi, in this report.
10) http://accc.riken.jp/ .

III. RESEARCH ACTIVITIES II(Material Science and Biology)

1. Atomic and Solid State Physics (Ion)Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 53

Control of electrical conductivity in diamond by boron implantation—application of high-temperature and high-pressure annealing
H. Yamazaki,∗1 T. Minamidate,∗2 M. Kidera,∗1 A. Yamamoto,∗3 R. Kato,∗2 and H. Ueno∗1
Diamond is an excellent electrical insulator with alarge band gap of 5.5 eV. Interestingly, it becomes a semiconductor when doped with a small amount of boron(for p-type) or phosphorus (for n-type). Ekimov et
al. reported that B-doped diamond, when doped beyond the metal-to-insulator transition at nB ∼ 3 ×1020 B/cm3 , shows superconductivity in samples grownby high-pressure and high-temperature synthesis.1) Theoretically, the superconducting critical temperature Tc
can be increased substantially by reducing the eﬀects ofdisorder in the B-doping processes.2) For a higher Tc ,more subtle control of doping using CVD and/or MBE
methods is required, whereas a diﬀerent method basedon ion implantation is also worth investigating, since itenables selective ion doping in a controlled manner.
We attempted to control the electrical conductivity
in diamond by means of the ion-implantation techniquewith the use of RILAC at RIKEN. In our study, for nand p-type semiconductors (and possibly superconductors), nitrogen and boron ions are implanted into diamond, respectively. By changing the beam intensity andirradiation time, the concentration of nitrogen or boron
was controlled. Note that achieving an n-type semiconductor, and needless to say an n-type superconductor,
by the nitrogen-doping of diamond is challenging, sincenitrogen behaves as a deep donor in diamond and does
not contribute to conductivity.3) The electrical conductivity observed in the nitrogen-implanted diamonds (e.g.,
at nN ∼ 7.5 × 1021 N/cm3 ) is, therefore, most likely explained in terms of the carbon atoms connected via thesp2 bonding produced by radiation damage. The Raman
spectra support this scenario.
In this ﬁscal year, we mainly investigated boron-

Fig. 1. Phase diagram of carbon. The annealing condition inthis work is indicated by a red circle.
∗1
∗2
∗3

RIKEN Nishina Center
Condensed Molecular Materials Laboratory, RIKEN
Graduate School of Engineering and Science, Shibaura Institute of Technology

Fig. 2. Laser Raman spectra (632.8 nm excitation) of the
as-implanted and annealed samples for nB ∼ 6.8 ×
1022 B/cm3 . The broken lines indicate the fluorescence emission of the zero-phonon line (ZPL) and nphonon lines (nPLs; “phonon side band”) due to negatively charged nitrogen-vacancy (NV− ) defect centers.

implanted diamonds. Boron ions were implanted into
diamond crystals (each size is 1 × 1 × 0.3 mm3 ) at
5 keV (implantation depth: ∼10 nm) using an ECR ion
source.4) We prepared ten samples of diﬀerent concentrations ranging from nB ∼ 4.9 × 1020 to 6.8 × 1022 B/cm3 .
Measurements of the magnetization and electrical resistivity show that the as-implanted diamond samples do
not exhibit superconducting transitions, even though nBvalues are nominally beyond the metal-to-insulator transition at 3 × 1020 B/cm3 . In order to reduce the lattice damage produced during the implantation, we attempted annealing treatments after implantation. As
the phase diagram of carbon (Fig. 1) shows, diamond is
not stable at low pressures; we annealed the samples at
800◦ C and 4 GPa (in the diamond-stable region) for one
hour. The annealed samples, however, indicate no sign ofsuperconductivity. Rather, the annealing treatment degraded the diamond crystals: the (222) peak at a higher
angle in x-ray diﬀraction measurement disappeared after
annealing, whereas the (111) peak remained. Figure 2
shows a typical change in the Raman spectra after annealing. The ﬂuorescence emission due to NV− defectcenters is clear, suggesting that the annealing treatment
promotes the NV formation process, where nitrogen ionshave been embedded in the Ib-type diamond as impurities. Hereafter, we must also consider the eﬀect of theNV− centers on the electrical conductivity in the implanted diamonds.
References

1) E. A. Ekimov et al., Nature 428, 542 (2004).
2) T. Shirakawa et al., J. Phys. Soc. Jpn. 76, 014711 (2007).
3) S. J. Sque et al., Phys. Rev. Lett. 92, 017402 (2004).
4) M. Kidera et al., Eur. J. Mass Spectrom. 13, 239 (2007).

- 139 -

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 53

Superconducting proximity eﬀect in epitaxial
Nb(110)/Au(111)/Nb(110) trilayers
H. Yamazaki,∗1 N. Shannon,∗2 and H. Takagi∗3
Superconducting electronics, in which currents are carried by superconducting pairs of electrons, have great
potential for future application in quantum computing. An essential element of superconducting circuits
is the π junction, in which the phase of a superconducting wave function is inverted. One promising approach to building such a junction is to exploit the interplay between superconductivity and magnetism in superconductor (SC)/ferromagnet (FM)/SC heterostructures. Such multilayer structures are widely believedto achieve a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)
state, in which the superconducting proximity eﬀect
drives a superconducting order with oscillating phasewithin the FM layer.1) However, this approach suﬀers
from a serious drawback that the ferromagnetic elements
tend to suppress superconductivity, forcing devices tooperate at lower temperatures and with lower criticalcurrent densities.
In this study, we show that, in epitaxial Nb(110)/
Au(111)/Nb(110) trilayers, the equilibrium superconducting state presents strong evidence of 0-π state transitions as a function of the Au-layer thickness (tAu ).
Through the analysis of experimental data, we makea reasonable argument that a form of order-parameter
oscillation, similar to the FFLO-like state in FM for
SC/FM/SC junctions, is intrinsic to the proximityinduced Cooper pairs in the Au(111) layer. We tentatively ascribe this eﬀect to the spin-orbit coupling (SOC)
within the Au layer. Where SOC lifts the degeneracy between “up” and “down” spin electrons, electron pairs canform with a non-zero momentum. This leads to FFLOlike oscillations of the superconducting order parameterin real space. In the fcc lattice of Au, inversion symmetry is broken in the direction perpendicular to the (111)plane because of the ABCABC. . . stacking sequence of
atomic planes, and the lack of inversion symmetry leads
to the emergence of SOC.
We prepared a series of Nb(110)/Au(111)/Nb(110)Fig. 1. Schematic diagram of a vertical section of the sample
and the reversal images of RHEED patterns obtained in
the growth process (right).
∗1
∗2
∗3

RIKEN Nishina Center
Okinawa Institute of Science and Technology Graduate University
Max-Planck-Institute for solid state research

Fig. 2. Critical current density Jc of the Nb/Au[tAu ]/Nb trilayers at 4.2 K and 6.0 K (ML: atomic monolayer).

trilayers on single crystals of Al2 O3 (1120) using MBE
method. The sample structure is shown in Fig. 1. We
will focus on single-domain samples (0 < tAu ≤ 2.10 nm),the superconducting properties of which are uniquely determined by tAu . The superconducting critical current
density Jc in zero magnetic ﬁeld was estimated from thewidth of the M-H hysteresis curve for H// sample plane
by using a Bean model.2) The data in Fig. 2 appear exactly like those for FM/SC multilayers, which have been
conﬁrmed to exhibit the 0-π state transitions as a function of tFM .3) Following previous articles,3,4) we used theequation:
Jc = Jc0 | sin y|/y,

where

eﬀ
y = 2πEex
tAu /hVfAu .

(1)

The solid and dashed lines in Fig. 2 show theoretical ﬁts
to the data for 6.0 K and 4.2 K, respectively. Fits are
eﬀ(= 84.6 meV) for νfAu =obtained as a function of Eex
1.39 × 106 m/s and the ratio Jc0 (4.2 K)/Jc0 (6.0 K) =eﬀ
is an eﬀective parameter characterizing
5.0, where Eex
the order-parameter oscillations in the Au layer, νfAu theFermi velocity of Au, and Jc0 the overall scale for Jc .
eﬀ(=84.6 meV) is consistent with the
The value of Eex
SOC strength (120 meV) of conduction electrons in Au.
A pairing state should occur between two electrons on
the SOC-induced split parts of the Fermi surface. One
might refute this argument on the grounds that a diﬀerence of 84.6 meV in energy between the spin-split bands
is too large for the electrons to form a pair since thesuperconducting gap is no more than 1.40 meV in Nb.
However, this is not the case with regard to the proximity eﬀects.5) Clearly, a theory is needed that treats the
SOC eﬀect on the proximity-induced Cooper pairs in a
SC/normal metal/SC system.
References

1) A. I. Buzdin et al., JETP Lett. 35, 178 (1982).
2) E. M. Gyorgy et al., Appl. Phys. Lett. 55, 283 (1989).
3) Y. Blum et al., Phys. Rev. Lett. 89, 187004 (2002).
4) A. I. Buzdin, Rev. Mod. Phys. 77, 935 (2005).
5) T. Kontos et al., Phys. Rev. Lett. 86, 304 (2001).

- 140 -

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 53

Simultaneous cluster dissociation and optical pumping of Ag insuperfluid helium using a single UV laser
T. Yamamoto,∗1,∗2 K. Imamura,∗1 A. Takamine,∗1 W. Kobayashi,∗2 Y. Takeuchi,∗1,∗2 M. Doi,∗1,∗2 H. Ueno,∗1 and
Y. Matsuo∗1,∗2
We have been developing a laser spectroscopy method
for atoms introduced into superﬂuid helium (He II).
We generate spin polarization by the optically pumping
the atoms and perform laser-radiofrequency and lasermicrowave (MW) double resonance. This method enables us to determine the nuclear spins and electromagnetic moments through measurements of Zeeman splitting and hyperﬁne structure (HFS) splitting. Moreover,because HFSs in He II shift slightly from the value invacuum, we are studying such an interaction between
He II and atoms.
We have successfully measured HFSs of alkali atoms
such as stable 85, 87 Rb and 133 Cs in He II and observed
small diﬀerences from those in vacuum.1,2) Currently, we
are attempting to apply this method to group 11 atoms
to verify whether a similar diﬀerence appears in atoms
other than alkali metal elements. The HFS transition of
the stable isotope 197 Au atom in He II was observed using this technique.3) To discuss the diﬀerential hyperﬁneanomalies between isotopes, it is necessary to measure
the HFSs of at least two isotopes. Silver is a good candidate with two stable isotopes, 107 Ag and 109 Ag, thenatural abundance ratio of which is almost 1:1.
In oﬄine experiments, atoms have been introduced
into He II using a two-step laser sputtering method,
namely, by laser ablation and laser dissociation. As theﬁrst step, a metal sample placed above the He II surface
is ablated by the second-harmonic pulse of a Nd: YAG
laser (wavelength: 532 nm, repetition rate: 10 Hz, pulse
width: 8 ns, pulse energy: ∼5 mJ). Only clusters generated by the ablation process can be immersed in He
II. Subsequently, atoms are supplied by the dissociation
process for the spectroscopy of atoms in He II. Althougha femtosecond Ti:Sa laser (wavelength: 800 nm, repetition rate: 500 Hz, pulse width: ∼120 fs, pulse energy:∼200 µJ) has been eﬃcient in the dissociation for various atomic species, we found this is not the case for Ag
clusters.4) Inspired by a report that Ag clusters in He II
droplets show absorption in the range of 330–360 nm instead of 800 nm,5) our group applied the third-harmonic
pulse of Nd:YAG laser (wavelength: 355 nm, repetition
rate: 20 Hz, pulse width: 5 ns, pulse energy: 8 mJ) tothe dissociation process. The dissociation of Ag clusters
was clearly conﬁrmed by the generation of spin polarization of Ag atoms in He II through optical pumping.6)
For further study of Ag atoms using the laser-RF/MW
double resonance method, it is indispensable to increase
laser induced ﬂuorescence (LIF) photon counts.
In particular, increasing the power of the pumping∗1∗2

RIKEN Nishina Center
Department of Advanced Sciences, Hosei University

Fig. 1. Variation of LIF intensity with a magnetic field.

laser is promising because the LIF intensity is proportional to the pumping laser power for atoms in superﬂuid helium.7) This approach should also be eﬀective if
the pumping laser simultaneously function as the dissociation laser.
Herein, we report the introduction of the forth harmonics of a new DPSS laser (wavelength: 335 nm, repetition rate: 20 kHz, pulse width: ∼20 ns, pulse energy:
5 µJ). The wavelength of the laser matches the wavelength for both Ag cluster dissociation and Ag atomic
excitation in He II. Since the output power of the laser
is greater than 100 mW on average, it is expected thatthe laser pulses can dissociate Ag clusters.
Figure 1 shows the result of increase and decrease in
LIF intensity when a magnetic ﬁeld (0–11.5 G) and an
RF ﬁeld (10.0 MHz) were applied to Ag atoms in He
II. When a suﬃcient magnetic ﬁeld is applied, spin polarization is achieved, and the LIF intensity decreases.
In addition, when a constant RF is applied, the LIF intensity increases at the magnetic ﬁeld that provides the
Zeeman splitting energy corresponding to the resonant
RF. We conﬁrmed that the single laser can eﬃciently
perform as both the dissociation and pumping laser for
Ag atoms. In the next step, we will measure the HFS
splitting of Ag atoms in He II by using this laser system.
References

1) T. Furukawa, Doctral thesis, Osaka University (2007).
2) K. Imamura et al., Hyperfine Interact. 230, 73 (2014).
3) T. Fujita et al., RIKEN Accel. Prog. Rep. 47, 212 (2014).
4) T. Fujita et al., RIKEN Accel. Prog. Rep. 50, 196 (2014).
5) E. Loginov et al., Phys. Rev. Lett. 106, 233401 (2011).
6) W. Kobayashi et al., RIKEN Accel. Prog. Rep. 52, 19 (2019).
7) K. Imamura et al., Appl. Phys. Express. 12, 016502 (2019).

- 141 -

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 53

Baseline correction system for precision measurement of the hyperfine
structure of Rb atoms in superfluid helium
M. Doi,∗1,∗2 K. Imamura,∗2 A. Takamine,∗2 Y. Takeuchi,∗1,∗2 T. Yamamoto,∗1,∗2 H. Ueno,∗2 and Y. Matsuo∗1,∗2
We have been developing a laser spectroscopic method
for the atoms injected into superﬂuid helium (He II)with the objective of studying the nuclear structure of
unstable nuclei with low production yields and short
lifetimes. In this method, laser-induced ﬂuorescence(LIF) is observed by applying the laser-radiofrequency(RF)/microwave (MW) double resonance method to
atoms in He II to measure Zeeman splitting and hyperﬁne structure (HFS). It enables us to determine thenuclear magnetic moments and nuclear spins that reﬂect
nuclear structure.
One of the eﬀective ways to introduce atoms to He II
is a two-step laser sputtering method. In a previous experiment, we successfully measured the hyperﬁne structure of 133 Cs atoms in He II with an uncertainty of 10−5
via the laser-microwave double resonance method.1) In
order to discuss the hyperﬁne anomaly of atoms in He
II, it is necessary to measure hyperﬁne structure splittings for at least two isotopes. We attempted to show
the feasibility of deducing hyperﬁne splittings with anaccuracy and a precision of 10−6 for Rb, which has two
stable isotopes. However, it has been diﬃcult to realize
measurement with a suﬃciently high precision owing to
the ﬂuctuation of the number of observed photons when
we use the two-step laser sputtering method to supply
atoms to He II. To overcome this diﬃculty, a baseline
correction system to cancel the ﬂuctuation of the number of atoms was developed.2)
The baseline correction system consists of an electrooptic modulator (EOM) to switch the polarization of theexcitation laser quickly and a multichannel scaler (MCS)
equipped with multi-channel inputs to count photons forcircular and linear polarizations. It has been successfully demonstrated by observing the LIF count diﬀerence
between spin-polarized and unpolarized atoms that theFig. 1. (a) Switching of the polarization of the excitation
laser by EOM. (b) Schematic of the experimental setup
in a cryostat.
∗1∗2

Department of Advanced Sciences, Hosei University
RIKEN Nishina Center

Fig. 2. Laser RF double-resonance spectrum of 85, 87 Rb obtained using the baseline correction system.

baseline correction system works properly.2)
Next, we applied this system to a double-resonanceexperiment. With circularly polarized laser light irradiation, we expect to observe ﬂuorescence from atoms
only when the RF/MW frequency is resonant with the
Zeeman splitting or hyperﬁne structure while scanning
the RF/MW frequency. On the other hand, when thelaser light is linearly polarized, all the atoms are excited;
thus, the observed number of photons was proportional
to the number of atoms.
We performed an RF double-resonance experiment for
Rb atoms injected into He II using the baseline correction system. Rb atoms were irradiated with a 120-mW
Ti:Sa laser (wavelength: 780 nm, laser diameter: 2 mm)of either circular or linear polarization. Figure 2 shows
the spectrum obtained when we swept the RF frequency.
We observed two ﬂuorescence peaks. The peaks on theleft and right correspond to resonance for the Zeeman
splitting of 85 Rb and 87 Rb, respectively. The center frequencies of both peaks were consistent with the resonance frequencies estimated from our experimental condition. This result indicates that the baseline correction
system works well in the double-resonance experiment
as well as the previous work.3)
In the future, the present research will be extended bymeasuring the hyperﬁne structure of Rb with the baseline correction system to evaluate the hyperﬁne anomalyof Rb isotopes in He II, which requires a MW doubleresonance experiment with a long sweep time and, hence,an increased ﬂuctuation in the number of atoms.
References

1) K. Imamura et al., Hyperfine Interact. 230, 73 (2015).
2) M. Sanjo et al., RIKEN Accel. Prog. Rep. 52, 153 (2019).
3) T. Fujita et al., RIKEN Accel. Prog. Rep. 47, 212 (2014).

- 142 -

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 53

Profile measurement of laser microbeam produced by glass capillaries:
tilt dependence
M. Mori,∗1,∗2 T. Ikeda,∗2 Y. Hikima,∗1,∗2 S. Kawamura,∗1,∗2 and W. -G. Jin∗1
Tapered glass capillaries can simultaneously produce
ion and laser microbeams with diameters of several tensof µm.1,2) In the irradiation experiments at the RIKEN
Pelletron facility, for example, H and He ions with energies of a few MeV are used. Their ranges are only about
100 µm in water at most. Since it is diﬃcult to conﬁrm
incidence on the target by using detectors, the use ofa µm-order laser sight system prior to the ion irradiation plays an important role in avoiding mis-shootings.3)
The µm-order laser sight through a capillary was demonstrated with visible light and then extended to UV in
2018.4) This may be applicable to shorter wavelengths
such as X-rays. Moreover, a multi-quantum beam (laser+ ion) or (laser + laser) transmission through a capillary will be feasible. However, the transmission property
is diﬀerent between lasers and ions. Here, a laser beam
bending along the tilted capillary axis is reported, which
is known as the guiding eﬀect for keV-energy ion microbeams through the capillaries without any magnetic
ﬁeld.
Figure 1 shows the experimental setup.
A UV
laser 375 nm in wavelength was extracted from asemiconductor laser source (THORLABS L375P70MLD;
max.70 mW), and it entered a capillary mounted on a
precise stage after reﬂection on two mirrors. The powerof the laser microbeam was measured at a photodiode(OPHIR PD300) after a slit, which shields the scattered
light from the taper part of the capillary. The microbeam
was cut by a knife edge attached on a motorized stage(SURUGA SEIKI XYCV620-G-N) with a scan lengthand minimal step of 2 mm and 0.5 µm, respectively. The
knife edge was located 3 mm downstream of the capillary outlet, of which the corresponding distance from thecenter of the tilting (θ) was 72 mm for a capillary withan outlet of 18 µmϕ.
The proﬁles were obtained by diﬀerentiating the beam
power as a function of the knife-edge position. The peakshift according to θ is shown in Fig. 2. A steeper decrease for the θ(+) tilting, i.e., an asymmetry of the
proﬁles in the θ(+) and θ(−) tilting, can be found andmay be attributed to the slightly asymmetric shape of
capillaries. Satellite peaks are due to higher-order ringsof the Fraunhofer pattern.1) The angles reconstructed

Fig. 1. Experimental setup with the knife-edge method.
∗1∗2

Department of Physics, Toho University
RIKEN Nishina Center

Fig. 2. Laser microbeam profiles measured by tilting the capillary in the θ(+) and θ(−) directions.

Fig. 3. Reconstructed angles as a function of θ.

from the measured peak positions are summarized for
ﬁve outlet sizes, as shown in Fig. 3. The reconstructed
angle is found to be nearly proportional to θ. The solidline shows y = x as a guide to the eye. Most of thereconstructed angles are less than the tilting angles, especially for the outlets of 53, 63, and 80 µmϕ. Such aphenomenon is not found in ion experiments.5,6) This isconsidered a result of diﬀerent transmission mechanismsof ions and light in capillaries. Because ions lose theirenergies during scattering at the inner wall, they cannot
penetrate the capillary window, and only those parallel to the capillary axis contribute to the output beam.
However, light does not lose its energy during scatteringand always contributes to the output beam. We concluded that the knife-edge method is capable of measuring the laser microbeam proﬁle. Further, laser light ispossibly guided by the capillary tilting. The next step
will be to test the dependence on the divergence of theinitial laser beam.
References

1) K. Sato et al., RIKEN Accel. Prog. Rep. 51, 21 (2018).
2) T. Ikeda et al., Quantum Beam Sci. 4, 22 (2020).
3) T. Ikeda et al., RIKEN Accel. Prog. Rep. 51, 245 (2018).
4) S. Kawamura et al., J. Phys. Soc. Jpn. 89, 055002 (2020).
5) M. Ikekame et al., RIKEN Accel. Prog. Rep. 52, 164 (2019).
6) T. Ikeda et al., Nucl. Instrum. Methods Phys. Res. B 470, 42(2020).

- 143 -

2. Atomic and Solid State Physics (Muon)

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Study on magnetism of defective reduced graphene oxides
R. Asih,∗1,∗2 D. P. Sari,∗3,∗2 M. A. Baqiya,∗1 Darminto,∗1 and I. Watanabe∗2
The origin of magnetism in graphene-based materials has been determined to be related with the presence of defects in their sheets.1–3) A graphene-derived
material that has a signiﬁcant amount of defects is reduced graphene oxide (rGO). The magnetic state of rGO
has been reported to vary depending on the defect state
and, thus, on the preparation history. Paramagnetic,4)super-paramagnetic,5) and even room-temperature ferromagnetic states1,2) have been reported to coexist in
rGO.6) A magnetic ordering is expected to appear in thepresence of a suﬃcient amount of defects in rGO.3) In
this study, we investigate the presence of possible roomtemperature magnetic ordering in rGO prepared using
the green-synthesized method7) by means of muon-spin
relaxation (µSR).
The investigation of the Raman spectra of the synthesized rGO revealed the presence of a signiﬁcant amountof defects and that the amount of defects can be enhanced by thermal reduction.7) In addition to sp2 carbon hybridization (C = C), the main functional group,
the presence of diﬀerent types of oxygen functionalities
was observed in the synthesized rGO.7,8) The magnetization at 300 K was found to increase with an increasing amount of defects, and the enhancement was
not attributed to magnetic impurities.7) Moreover, a divergence in χ(T ) was observed under ﬁeld cooling (FC)and zero-ﬁeld cooling (ZFC) conditions, which might indicate that the blocking temperature is noticeable at
300 K. Thus, the µSR experiment was subsequently performed to microscopically investigate magnetism in rGO
at 300 K.
The inset in Fig. 1 shows the zero-ﬁeld (ZF) time spectrum of the synthesized rGO at 300 K. An appreciablemuon-spin precession on top of the decaying signal wasobserved in the spectrum, which is somehow similar tothat observed in as-prepared graphene.9) The spectrum
can be well ﬁtted by a single precession component anda Lorentzian decay. The ﬁtting results in a hyperﬁne
ﬁeld of about 6 G. Such coherent muon-spin precession
could indicate the presence of long-range magnetic ordering and/or the formation of a muonium (Mu)-H entangled state.9) Meanwhile, the Lorentzian decay signiﬁes muon diﬀusion through a carbon surface.10) Under
the assumption of the Mu-H dipolar interaction, a dipolar ﬁeld of approximately 5 G is obtained which is equal
to a Mu-H internuclear distance of 1.344 ± 0.005 . Furthermore, a longitudinal-ﬁeld (LF) was applied to decouple the muon spin from the electron spin. The LF
dependence of the muon-spin repolarization fraction is
∗1
∗2
∗3

Department of Physics, Institut Teknologi Sepuluh Nopember,Indonesia
RIKEN Nishina Center
Department of Regional Environment Systems, Shibaura Institute of Technology

Fig. 1. Field dependence of the muon-spin repolarization
fraction of the synthesized rGO at 300 K fitted by a simple model for the muonium radical (Eq. (1)). Inset: zerofield (ZF) µSR spectrum (at 300 K) of the synthesizedrGO fitted by the summation of Lorentzian decay and asingle precession component, as described in the text.

displayed in Fig. 1, which can be well ﬁtted by a simple
model for isotropic muonium with the function describedin Eq. (1).10)
Pexp = Pdia + Arad [x2 /(x2 + 1)],

(1)where x = B/Bhyp . Bhyp is the hyperﬁne ﬁeld for freemuonium. Pdia and Arad are the diamagnetic fraction
and the amplitude of the radical fraction, respectively.
The obtained Bhyp is about 4.35 ± 0.24 G, which is almost as large as that procured from the ZF spectrum.
This Bhyp value corresponds to a hyperﬁne frequency of
12(1) MHz, which is close to the instrument cut-oﬀ of
13 MHz. This can be the reason why ∼45% of the implanted muons were not observed in the ZF spectrum.
Furthermore, a more detailed analysis in conjunction
with ﬁrst-principles calculations is required to conﬁrm
that the observed muon-spin precession originates from
Mu-H interaction to form the CHMu group as suggested
for hydrogenated graphene.9)
References

1) S. Qin et al., Carbon 78, 559 (2014).
2) G. Khurana et al., Nanoscale 5, 3346 (2013).
3) J. Tǔcek et al., Chem. Soc. Rev. 47, 3899 (2018).
4) M. Sepioni et al., Phys. Rev. Lett. 105, 207205 (2010).
5) S. K. Sarkar et al., Physica E 64, 78 (2014).
6) P. Z. Sun et al., Nano Res. 7, 1507 (2014).
7) D. Darminto et al., IEEE Trans. Mag. 54, 1 (2018).
8) R. Asih et al., Mat. Sci. Forum 966, 290 (2019).
9) M. Riccò et al., Nano Lett. 11, 4919 (2011).
10) M. Gaboardi et al., J. Mater. Chem. A 2, 1039 (2014).

- 145 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Magnetic ground state of Jeﬀ = 0 Mott insulator Ag3 LiRu2 O6 underpressure
T. Takayama,∗1,∗2 M. Blankenhorn,∗1,∗2 A. Krajewska,∗1,∗2 D. P. Sari,∗3,∗4 I. Watanabe,∗4 and H. Takagi∗1,∗2,∗5
The interplay of strong spin-orbit coupling (SOC)and electron correlation in heavy transition-metal oxides has been found to give rise to unprecedented electronic phases. Among such oxides, Mott insulators witha d4 (t42g ) conﬁguration are expected to exhibit exotic
magnetism. In the d4 systems, Hund’s coupling produces an S = 1 and Leﬀ = 1 state. SOC thus yields
a spin-orbit-entangled Jeﬀ = 0 ground state. Although
the Jeﬀ = 0 state is non-magnetic, it may interact magnetically with each other through the excited Jeﬀ = 1
levels separated by SOC. It was proposed that the system undergoes magnetic ordering when the energy gainby magnetic interactions overcomes the energy cost of
the Jeﬀ = 0 to 1 excitation, which is dubbed excitonic
magnetism.1) Particularly, when the Jeﬀ = 0 state is arranged on a honeycomb lattice, exotic magnetic groundstates such as a spin-nematic phase or magnetic triplon
liquid, are expected to emerge.
The Jeﬀ = 0 honeycomb lattice may be realized in
Ru4+ (4d4 ) oxides. However, a honeycomb ruthenate
Li2 RuO3 is known to display spin-singlet dimerizationaccompanying orbital ordering.2) In the dimerized state,
the spin and orbital degrees of freedom are quenched,and spin-orbit coupling is inactive. In order to suppress the dimerization and realize the Jeﬀ = 0 state,
we employed an ion-exchange reaction and obtained thesilver-intercalated compound Ag3 LiRu2 O6 .3) The crystal structure at room temperature shows no appreciable
distortion in the Ru honeycomb lattice, indicating thedisappearance of dimerization.
The magnetic susceptibility χ(T ) of Ag3 LiRu2 O6 increases on cooling from room temperature and showssaturation below 100 K. Interestingly, no magnetic orderis observed down to 0.3 K. From inelastic neutron scattering and 7 Li-NMR measurements, Ag3 LiRu2 O6 was
found to have a gapped magnetic excitation of ∼35 meV,as expected for the Jeﬀ = 0-type singlet ground state.4)
The singlet ground state suggests that the magnetic exchange interactions are not strong enough to drive excitonic magnetism. We thus investigated the magnetic
properties under high pressures as an attempt to enhance magnetic interactions. Indeed, under a pressure
above 0.4 GPa, χ(T ) shows a broad peak below room
temperature, indicating the appearance of a pressureinduced electronic phase transition. However, the natureof the magnetic ground state under pressure remains un∗1
∗2
∗3
∗4
∗5

Max Planck Institute for Solid State ResearchInstitute for Functional Matter and Quantum Technologies,
University of Stuttgart
Graduate School of Engineering and Science, Shibaura Inst.
of Tech.
RIKEN Nishina Cente
Department of Physics, University of Tokyo

Fig. 1. Zero-field time spectra of muon asymmetry for
Ag3 LiRu2 O6 under a pressure of 0.64 GPa.

clear.4)
In order to understand the magnetic ground state under pressure, we performed a muon spin rotation measurement on Ag3 LiRu2 O6 under pressure by using ARGUS, ISIS. At ambient pressure, the time dependenceof muon asymmetry at low temperatures only shows amonotonic decrease, which is consistent with the nonmagnetic singlet ground state. As shown in Fig. 1, thetime dependence of muon asymmetry did not show any
pronounced change down to 2 K even at a pressure of
0.64 GPa, while χ(T ) showed a broad peak at approximately 150 K at that pressure. This suggests that thebroad peak observed in χ(T ) under pressure is not associated with a magnetic ordering but represents anotherelectronic phase transition while retaining the nonmagnetic ground state.
The nature of the pressure-induced nonmagnetic
phase, revealed by the µSR measurement, remains elusive. The x-ray diﬀraction under pressure excluded therestored dimerization in this pressure range. The candidates of possible ground states include a spin-orbit
triplon liquid, molecular orbital formation, or ﬂuctuating dimers. We are currently attempting to determine
the nature of this phase in combination with other spectroscopic probes.
References

1) G. Khaliullin, Phys. Rev. Lett. 111, 197201 (2013).
2) Y. Miura et al., J. Phys. Soc. Jpn. 76, 033705 (2007).
3) S. A. J. Kimber et al., J. Mater. Chem. 20, 8021 (2010).
4) T. Takayama et al., in preparation.

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Non-magnetic ground state of In2 Ru2 O7 probed by muon spin rotation
T. Takayama,∗1,∗2 A. Krajewska,∗1,∗2 I. Watanabe,∗3 D. P. Sari,∗3,∗4 and H. Takagi∗1,∗2,∗5
The interplay of charge, spin, and orbital degrees of
freedom in correlated systems gives rise to a variety of
exotic electronic states. Among these materials, ruthenium oxides containing Ru4+ cations (d4 electron count),which host orbital degeneracy, display a variety of spinorbital ordering phenomena such as spin singlet dimer
formation in Li2 RuO3 1) and La2 RuO5 .2) A particularlyinteresting situation may be found when Ru4+ cations
are placed on a frustrated lattice, for example, in pyrochlore ruthenate Tl2 Ru2 O7 , which displays a metalto-insulator transition with a spin-singlet ground state.3)
The spin-singlet state is discussed to originate from theformation of 1D zig-zag Haldane chains and is potentially the first example of such a system emerging in
a 3D lattice. While there is still discussion on theplausibility of the Haldane-chain scenario, the origin of
this unique state and behavior distinct from those ofother pyrochlore ruthenates remains unclear. Pyrochoreruthenates appear to be an interesting playground fornovel electronic states.
We discovered a new pyrochlore ruthenate In2 Ru2 O7
which adopts a weakly distorted pyrochlore structure at
300 K. In2 Ru2 O7 , is an insulator and shows Curie-Weissbehavior at high temperatures. At Tm ∼ 220 K, a sharp
drop in magnetic susceptibility χ(T ), similar to those ofother spin-singlet ruthenate compounds,1–3) is observed.
To elucidate the nature of the ground state of In2 Ru2 O7
and the absence of a long-range magnetic ordered state,
the temperature dependence of zero-field muon spinrotation (ZF-µSR) is necessary. In this report, we
present the result of a ZF-µSR experiment performedon CHRONUS at ISIS, UK. We recorded the time evolution of ZF-µSR spectra of In2 Ru2 O7 from 300 K down
to 10 K (Fig. 1(a)). No oscillation down to the lowest temperature was observed, excluding the presenceof long-range antiferromagnetic order and pointing to a
non-magnetic spin singlet state. The data over the wholestudied temperature range were fitted to a “stretched”
exponential:βPz (t) = e−(λt) ,(1)

where Pz (t) is the asymmetry, t is the time, λ is therelaxation rate, and β is the shape parameter. We observed a cross-over from a Gaussian-like to a Lorentzianlike damping with decreasing temperature (Figs. 1(a)and (b)). The high-temperature and low-temperature
response can be explained by the slowing behaviour ofthe fluctuations of dilute Ru spins, which originate from
∗1
∗2
∗3
∗4
∗5

Max Planck Institute for Solid State ResearchInstitute for Functional Matter and Quantum Technologies,
University of Stuttgart
RIKEN Nishina Center
Graduate School of Engineering and Science, Shibaura Institute of Technology
Department of Physics, University of Tokyo

Fig. 1. (a) Time evolution of ZF-µSR spectrum of In2 Ru2 O7
powder sample at various temperatures. (b) Temperaturedependence of λ and β fitted using equation (1).

the defects present in the system, or by the appearanceof slowly fluctuating quasi-particle spins excited fromthe spin-singlet state induced by injected muons. Such a
response was reported in other materials hosting a spinsinglet ground state.5,6) In addition, a sharp change in λand β is observed at Tm (Fig. 1(b)). The enhancementof λ below Tm would point to the opening of a gap.
In this report, the ground state of In2 Ru2 O7 was investigated with ZF-µSR. No evidence of long-range magnetic order was found; hence, the non-magnetic groundstate was confirmed. The temperature dependence ofthe relaxation rate implies the opening of a gap. Other
techniques such as resonant inelastic x-ray scattering
could aid the determination of the gap size.
References

1) Y. Miura et al., J. Phys. Soc. Jpn. 76, 033705 (2007).
2) H. Wu et al., Phys. Rev. Lett. 96, 256402 (2006).
3) S. Lee et al., Nat. Mat. 5 (2006).
4) K. Kojima et al., Phys. Rev. Lett. 74, 3471 (1995).
5) S. J. Blundell et al., Phys. Rev. B 77, 094424 (2008).
6) M. Miyazaki et al., Phys. Rev. B 75, 09440 (2007).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Short-range magnetic order in the frustrated antiferromagnet
Cu5 (PO4 )3 (OH)4 (pseudomalachite)
H. Kikuchi,∗1 Y. Fujii,∗2 U. Widyaiswari,∗3 and I. Watanabe∗3
Geometrically frustrated magnets have recently been
attracting much interest, because they are expected
to exhibit new physical states including spin liquid.
Almost every frustrated magnet studied so far, e.g.,
kagomé, triangular, and pyrochlore lattices, are basedon triangular units. The spin frustrated eﬀect, however,is not restricted to a triangle but appears if antiferromagnetic spins are on a polygon with odd-number edges
such as a pentagon. A lattice containing pentagons as
its unit can aﬀord a new category for the spin frustration eﬀect. Cu5 (PO4 )3 (OH)4 (mineral name: pseudomalachite) is an orthorhombic crystal1) with three
crystallographically inequivalent sites of copper. Layers consisting of face-shared CuO6 octahedrons extend
in the bc plane and are separated by interlayer PO4
tetrahedrons. A spin network in the bc plane formed
by Cu2+ ions (S = 1/2) has a unique structure composed of triangles and pentagons.
We measured the magnetic susceptibility, speciﬁc
heat, and high-ﬁeld magnetization of pseudmalachiteusing natural mineral samples.2) The sign of the Weisstemperature is found to be negative, indicating that thedominant interaction is antiferromagnetic. The speciﬁcheat C(T ) has a broad maximum at Tf ≈ 4.2 K, whereχ(T ) shows a peak anomaly.
The relative change of C(T ) at Tf is very small if thistransition is a long-range magnetic order.
The entropy change associated with the magnetic order was estimated to be approximately 5.5 J/(K·mol),Fig. 1. ZF-µSR spectra of pseudomalachite.
∗1
∗2
∗3

Department of Applied Physics, University of Fukui
FIR Center, University of Fukui
RIKEN Nishina Center

Fig. 2. Temperature dependence of the relaxation rate λ.

which is only one-ﬁfth of the expected value 5R ln 2
≈ 28.8 J/(K·mol). In order to clarify the magnetic ordering transitions in this frustrated magnet, measurements using a microscopic and dynamic probe is highly
desired.
Figure 1 shows the zero-ﬁeld muon spin relaxation(ZF-µSR) spectra measured down to 1.6 K. At relatively high temperatures, the spectra follow Gaussian
curves.
Below approximately 4.2 K, the initial asymmetry
begins to decrease, and the form of the spectra changes
from the Gaussian to an exponential curve following
exp(−λ/t), where λ is the relaxation rate. Figure 2
shows the temperature dependence of the relaxation
rate obtained from a ﬁt to the observed spectra. λ has adistinct peak at approximately 4 K, where the anomaly
was observed in the speciﬁc-heat data. These observed
results clearly indicate that the magnetic phase transition occurs at Tf .
The spectrum below Tf , however, does not show any
spin rotation, suggesting that the internal ﬁeld is dynamic, rather than static. Furthermore, even in thelowest-temperature spectrum, spin relaxation remains,and ﬁnite spin ﬂuctuations seem to be present in theordered phase. These ﬁndings are consistent with ourmacroscopic indication that the transition is not a longrange order but has the character of a short-range order,
which originates from the geometrical spin frustrationeﬀect of the peculiar spin network of pseudomalachite.
References

1) G. L. Shoemaker et al., Am. Mineral. 62, 1042 (1977).
2) H. Kikuchi et al., J. Korean Phys. Soc. 62, 2037 (2013).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53µSR investigation of spin liquid states in magnetic properties of
MgTi2 O4 sample
U. Widyaiswari,∗1,∗2 N. Hanasaki,∗3 B. Kurniawan,∗2 and I. Watanabe∗1,∗2
The investigation of the geometrical frustration ofstrongly correlated systems is an interesting research
field. These systems show various exotic physical properties such as spin ice,1) and spin liquid states.2) In
the spin liquid state, spins do not show magnetic ordering even at the ground state. The spin liquid state
generally appears in triangular lattices and Kagome
lattice systems, which show geometrical frustration ofspin systems.2) Materials with pyrochlore structures,such as pyrochlore oxides and spinel compounds, thathave corner-sharing tetrahedral lattices are strong candidates to exhibit such exotic physical properties.
The spinel titanate, MgTi2 O4 , has 3d1 electron (S =1/2) within the Ti3+ ion and forms a pyrochlore lattice.3) At room temperature, the lattice structure of
MgTi2 O4 is cubic, and it shows a structural transition to a tetragonal lattice at Tst = 260 K.4) This
structural phase transition is accompanied by a metalinsulator transition and changes in magnetic properties.4) Isobe et al. proposed a spin-singlet insulator as
the ground state, which did not form any magnetic
ordering, suggesting the appearance of a spin liquidstate.4) At this moment, the spin state of MgTi2 O4 in
the ground state is still unclear and open for discussion. To explore the magnetic properties of MgTi2 O4 ,we performed microscopic measurements using muonspin relaxation (µSR) spectroscopy.
We measured the time evolution of the muon-spin
polarization in the zero-field (ZF) condition at the
RIKEN-RAL Muon Facility in the United Kingdom.
Time spectra measured at several temperatures areshown in Fig. 1(a). No muon-spin precession was observed in the time spectrum, indicating that there wasno long-range ordered state down to 6 K. We fitted thetime spectra using Eq. (1).
A(t) = A0 exp(−λt),(1)where A0 is the initial asymmetry of the muon spinat t = 0 and λ is the muon-spin relaxation rate. The
temperature dependence of λ is shown in Fig. 1(b).
λ gradually increases with decreasing temperature below 250 K. The increase of λ indicates the appearanceof a slowing down behavior of Ti3+ spin fluctuations.
However, there is no critical slowing down behavior
indicating the absence of a magnetic ordered state in
the current ZF-µSR study, as suggested in a previous
study.4) Accordingly, we plan to gather more detailed
information on the spin dynamics by performing µSR
∗1
∗2
∗3

Fig. 1. (a) ZF-µSR time spectra of MgTi2 O4 and (b) temperature dependence of muon spin relaxation rate.

RIKEN Nishina Center
Department of Physics, Universitas Indonesia
Department of Physics, Osaka University- 149 -

measurements in the longitudinal field (LF) condition.
References
1) M. J. Harris et al., Phys. Rev. Lett. 79, 2554 (1997).
2) L. Balents, Nature 464, 199 (2010).
3) S. Torigoe et al., Phys. Rev. B 98, 134443 (2018).
4) M. Isobe, Y. Ueda, J. Phys. Soc. Jpn. 71, 1848 (2002).

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Zero-point vibrational energy in the muon sites of La2 CuO4
M. R. Ramadhan,∗1,∗3 M. I. Mohamed-Ibrahim,∗2 S. Sulaiman,∗2 and I. Watanabe∗1,∗2,∗3
La2 CuO4 (LCO), the parent compound of high-TC
superconducting La2−x Ba/Srx CuO4 , is known to haveantiferromagnetic long-range ordering (AF-LRO) due
to its classiﬁcation as a Mott insulator. One accurate experiment to prove the AF-LRO characteristic
is the muon spin relaxation (µSR) technique. In thistechnique, the implanted muons that sense an internal
magnetic ﬁeld undergo Larmor precession. A previous
study on bulk LCO showed that the muon’s precession frequency is 5.5 MHz. Using the muon’s gyromagnetic ratio, γµ = 135.538817 MHz/T, the internal ﬁeld
(Bµexp ) felt by muons in bulk LCO was determined tobe approximately 410 G.1) A recent study on thin-ﬁlm
LCO showed that the implanted muons probe an additional internal ﬁeld approximately 100–120 G.2) While
two clear precessions have been shown in the past, theexact location of the implanted muon is still unknown,
which hinders the ability of the µSR technique to reveal more information and knowledge from the LCO
system.
Our group has been developing a technique to precisely estimate the muon position by utilizing density functional theory (DFT) calculations. Generalized gradient approximation (GGA) was chosen for
the exchange-correlation functional. The antiferromagnetic conﬁguration of the Cu spin from Vaknin etal. is utilized for the non-collinear calculation.3) Because LCO is a Mott insulator, we need to include
the Coulombic repulsion energy (Ueﬀ = 7.2 eV) inthe DFT calculation. From our previous reports,4,5)
we show the muon position from our DFT calculationand the muon’s perturbation eﬀect on the Cu-spin densities from a DFT perspective. However, even whenusing the distributed-spin model to calculate the internal ﬁeld, the calculated internal ﬁeld shows a 21%
diﬀerence with that observed from the experimentally(Bµexp = 410 G, while BµDF T = 498 G). We considered that this discrepancy originates from the zeropoint vibrational motion (ZPVM) of the muon, which
was not considered in our last report. As a ﬁne quantum particle, the muon should ﬂuctuate in its lowestenergy state. To include the ZPVM, we ﬁrst evaluate the three-dimensional Hartree potential (VµHartree )around the implanted muon’s position. Subsequently,
we simply calculate the eigenvalues and eigenfunction
for the ground state on those areas by using the following equation:[ 2]ℏ∇2i + VµHartree (r) Ψµ (r) = Eµ Ψµ (r),
(1)
2mµ
∗1
∗2
∗3

Department of Physics, Universitas Indonesia
School of Distance Education, Universiti Sains Malaysia
RIKEN Nishina Center- 150 -

Fig. 1. Muon probability density map in the xz-plane forthe (a) unperturbed LCO (b) perturbed LCO.

where mµ denotes to the muon mass, and |Ψµ |2 (r)is the probability that the muon exists at each position r. This Schrödinger equation was using the ﬁnitediﬀerence method. From our calculations, we conclude
that the energy convergence is achieved by considering
a 1.5 × 1.5 × 1.5 (Å) area from the center of the muon
position. The probability that the muon exists within
this designated area is 100%.
As reported previously, the implanted muon only
aﬀects the local crystal and electronic structure of
LCO. From our calculations, we obtained the groundstate energy as 0.82 eV for the unperturbed LCO and0.89 eV for the perturbed LCO. The slight increaseof the ground-state energy is very likely due to the
local deformation of the crystal structure. However,
the general description of the muon’s distribution overthe considered area is relatively the same as shown in
Fig. 1. By using the muon probability density mapof the perturbed LCO and the distributed-spin modelfrom our previous reports4,5) , we successfully reduced
the diﬀerences of the internal ﬁeld to less than 1%(Bµexp = 410 G, while BµDFT +ZPVM = 409 G). While
this method shows a promising result for the LCO system, it still needs to be tested in other systems, inorder to standardize this method to assist in µSR experiments.
References

1) J. I. Budnick et al., Phys. Lett. A 124, 103 (1987).
2) E. Stilp et al., Phys. Rev. B 88, 064419 (2013).
3) D. Vaknin et al., Phys. Rev. Lett. 58, 2802 (1987).
4) M. R. Ramadhan et al., RIKEN Accel. Prog. Rep. 51,
197 (2017).
5) M. R. Ramadhan et al., RIKEN Accel. Prog. Rep. 52,
173 (2018).

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Investigations of the quantum critical behavior of the S = 1/2 J1 -J2
square lattice antiferromagnets Sr2 Cu(Te1−x Wx )O6
S. Yoon,∗1 W. -J. Lee,∗1 S. Lee,∗1,∗2 C. H. Lee,∗1 A. Berlie,∗2 I. Watanabe,∗3 and K. -Y. Choi∗1
The J1 -J2 square-lattice Heisenberg model oﬀers a richreservoir of exotic quantum phases. Depending on theratio J2 /J1 (the ratio of exchange interactions between
a diagonal and a side of the square), the classical groundstates encompass Néel, columnar antiferromagnetic, anddisordered states. In particular, the B -site ordered double perovskites Sr2 Cu(Te1−x Wx )O6 (B = Cu2+ , B ′′ =Te6+ or W6+ ) with the tetragonal I4/m structure are
regarded as near-optimal realizations of the S = 1/2
Heisenberg model on a square lattice.1–4) Notably, themagnetic ground state of Sr2 Cu(Te1−x Wx )O6 can betuned from a Néel order (x = 0; J2 /J1 = 0.03) througha quantum spin liquid to a columnar antiferromagnetic
order (x = 1; J2 /J1 = 7.92) by varying the B ′′ cation
between Te6+ and W6+ ions.3) Owing to the similar sizesof the Te6+ and W6+ ions, Sr2 Cu(Te1−x Wx )O6 retains
the isostructural crystal lattice.
Unlike the crystal structure, the magnetism is susceptible to a composition of the B ′′ cations that are involvedin the magnetic exchange paths mediating the Cu2+ ions.
W6+ (5d0 ) hybridizes strongly with O 2p, thereby enabling the magnetic exchange path Cu-O-W-O-Cu (J2 ).
This is in sharp contrast to the Te6+ (4d10 ) ion, whichis in favor of J1 . The distinct role of the Te6+ /W6+
ions in relation to the exchange interaction poses thequestion as to whether the theoretically predicted spin
liquid phase can be achieved by controlling the composition of the B ′′ cations. Strikingly, there is tantalizing
experimental evidence for a quantum disordered state ina wide composition range of x ≈ 0.1 − 0.7.3) However,
the observed wide range of the spin-liquid phase is notcompatible with the theoretically predicted narrow composition range of x ≈ 0.23 ∼ 0.33. Recent theoretical
calculations have proposed quenched disorders as a key
ingredient to this discrepancy.3,4) To clarify the precise
nature of the ground state, we focus on the compositionsin the range of x = 0.05 − 0.1, which is at the boundary between the Neel antiferromagnetic order and thequantum disordered state.
Muon spin relaxation measurements were performed

Fig. 1. Muon spin polarization data observed at zero field
together with fitting curves (see the text for details) for
x = 0.05, 0.08, and 0.1.
∗1
∗2
∗3

Department of Physics, Chung-Ang university
Science and Technology Facilities Council, ISIS-RAL
RIKEN Nishina Center

Fig. 2. Temperature dependences of the relaxation rate (a)and its stretch exponent (b) for x = 0.05, 0.08, and 0.1.

on ARGUS and CHRONUS spectrometers at RIKENRAL towards understanding the precise nature of theground state and associated spin dynamics of the x =0.05, 0.08, and 0.1 compounds. Representative spectra
are shown in Fig. 1. No spontaneous muon spin oscillation is observed, indicating the absence of long-range
magnetic order. Moreover, all the observed µSR spectra are described by a stretched exponential function
exp[−(λt)β ], where λ is the muon relaxation rate andβ is the exponent.
Temperature dependences of the muon spin relaxation
rate, λ(T ), and its stretch exponent, β(T ), for x = 0.05,
0.08, and 0.1 are plotted in Fig. 2. λ(T ) of x = 0.05
starts to increase on cooling below 15 K and subsequently becomes constant for temperatures below 0.5 K.
In the x = 0.08 and 0.1 compounds, the crossover regime
shrinks, and onset temperatures shift to 6 K and 2 K for
x = 0.08 and 0.1, respectively; on the other hand, aplateau appears at 1 K for x = 0.1. We comment thatthe x = 0.05 and 0.1 compounds reveal the persistentspin dynamics below T = 0.5 − 1 K, which is often observed in frustrated magnets.
In addition, the T -dependence of the stretching exponent, β(T ), of x = 0.08 and 0.1 resemble λ(T ) while
increasing from 1 to 1.6 with decreasing temperature. In
sharp contrast, β(T ) of x = 0.05 decreases from 1.8 to
1.3 on cooling to 25 K. Noticeably, the low-T β(T ) of thecompounds is between those of Gaussian and Lorentzianrelaxation functions. When we consider that a Gaussianlike distribution is expected for dense disordered systems
or migrating unpaired spins in the matrix of singlet spins
and that a Lorentzian-like distribution is expected for
dilute systems, the ground state for x = 0.05, 0.08, and
0.1 is largely compatible with the random singlet picture
comprising resonating singlets and propagating orphanlike spins.
References

1) O. Mustonen et al., Nat. Commun. 9, 1085 (2018).
2) M. Watanabe et al., Phys. Rev. B 98, 054422 (2018).
3) O. Mustonen et al., Phys. Rev. B 98, 064411 (2018).
4) K. Uematsu, H. Kawamura, Phys. Rev. B 98, 134427 (2018).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Magnetic ordering and spin dynamics of Nd2 Ru2 O7 studied by µSR
U. Widyaiswari,∗1,∗2 H. Sakai,∗3 K. Inoue,∗3 N. Hanasaki,∗3 D. P. Sari,∗4 B. Kurniawan,∗2 and I. Watanabe∗1,∗2
Pyrochlore ruthenate (R2 Ru2 O7 ) is one of the systems that have a pyrochlore structure with the generalformula A2 B2 O6 O’, where A is a trivalent rare-earth
ion and B is a tetravalent transition metal ion. This
structure is composed of two corner-sharing tetrahedral lattices, which induce the magnetic frustration of
spins on each corner of the tetrahedral lattices. Novelphysical properties such as the spin-glass,1) spin-ice,2)and metal-insulator transition accompanied by a magnetic transition,3–5) are induced by this magneticallyfrustrated state. Those exotic properties originate
from the competition and/or cooperation among the
Coulomb interaction (U ), spin-orbit coupling (SOC)eﬀect, and exchange interaction between the rare-earth
and transition metal ions.
The temperature dependence of the speciﬁc heatof R2 Ru2 O7 shows a λ-type peak accompanied by asmall cusp in the temperature dependence of magnetic
susceptibility at the magnetic transition temperature,
TN .6–8) TN shifts to the higher temperature side fromapproximately 76 K to 160 K with increase in the ionicradius of R.6) Ku et al. showed that three anomalies
occur in Nd2 Ru2 O7 at 146 K, 21 K, and 1.8 K.8) At
present, the origin of those anomalies is unclear. Accordingly, we investigated the magnetic properties of
Nd2 Ru2 O7 by the muon spin relaxation (µSR) method
and compared the results with our previous results for
Nd2 Ir2 O7 .4,5)
The time evolution of the muon-spin polarization(µSR time spectrum) in zero ﬁeld (ZF) was measured
at several temperatures and analyzed by the following
two-component relaxation function:
A(t) = A1 exp(−λ1 t) + A2 exp(−λ2 t).

(1)

The ﬁrst and second components describe the fast andslow relaxation components, respectively. A1 and A2
are the asymmetry parameters while λ1 and λ2 are themuon relaxation rates of the two components.
We conﬁrmed from the current study an orderedstate of Ru spins below 146 K, showing a decrease in
the initial asymmetry parameter accompanied by theappearance of a critical slowing down behavior of the
Ru spin ﬂuctuations.9) Another anomaly of the muon
relaxation rate was detected around 30 K as a broad
dip in its temperature dependence.9) This anomaly
is unlikely to be due to the appearance of the magnetic ordering of Nd spins because no critical slowing
down behavior was observed at lower temperatures in
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Department of Physics, Universitas Indonesia
Department of Physics, Osaka University
Graduate School of Engineering and Science, Shibaura Institute of Technology- 152 -

Fig. 1. (a) ZF- and LF-µSR time spectra of Nd2 Ru2 O7
measured at various temperatures. An LF of 3850 G
was applied for LF-µSR measurement. (b) Temperature dependences of the slow relaxation rate in both
the ZF and LF condition.

Nd2 Ir2 O7 .4,5)
In order to clarify the anomaly around 30 K, we
measured µSR in the longitudinal-ﬁeld (LF) condition under an applied ﬁeld of 3850 G. Both ZF- andLF-µSR time spectra are shown in Fig. 1(a). We
conﬁrmed that the relaxation rate still showed theanomaly around 30 K in LF-µSR,9) but this anomaly
was slightly smaller compared to the case of ZF-µSR.
To obtain more information about the origin of theanomaly around 30 K, we are now planning to conduct
further µSR measurements of the LF scan at several
temperatures to investigate the change in spin dynamics.
References

1) J. G. Park et al., Physica B 328, 90 (2003).
2) M. J. Harris et al., Phys. Rev. Lett. 79, 2554 (1997).
3) K. Matsuhira et al., J. Phys. Soc. Jpn. 80, 094701(2011).
4) R. Asih et al., J. Phys. Soc. Jpn. 86, 024705 (2017).
5) H. Guo et al., Phys. Rev. B 88, 060411(R) (2013).
6) M. Ito et al., J. Phys. Chem. Solids 62, 337 (2001).
7) N. Taira et al., J. Solid State Chem. 152, 441 (2000).
8) S. T. Ku et al., J. Phys. Condens. Matt. 30, 155601(2018).
9) U. Widyaiswari et al., to be published.

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Muon spin relaxation study of solute-vacancy interactions during
natural aging of Al–Mg–Si–Cu alloys†
K. Nishimura,∗1,∗2 K. Matsuda,∗1,∗2 S. Lee,∗1 I. Watanabe,∗2 T. Matsuzaki,∗2 S. Wenner,∗3 and R. Holmestad∗4Age-hardenable aluminum alloys are strengthened bynanometer-sized atomic clusters and precipitates that are
coherent with the aluminum matrix. These are formedby the segregation of atoms (e.g., Mg and Si) from asolid solution, where the solute atoms occupy substitutional sites in fcc-Al. Such a solid solution comprisinga few at. % of alloying elements is achieved by solution
heat treatment (SHT)—an annealing step at 770–870 K.
The solid solution is highly unstable after quenching in
ice water after SHT (SHTQ). During further heat treatments at a lower temperature (artiﬁcial aging) and evenroom-temperature storage (natural aging), vacancies andsolute atoms co-diﬀuse and produce atomic clusters, withall atoms remaining at fcc-Al positions.1,2) The most important techniques to detect and quantify precipitatesin the Al-Mg-Si system have been transmission electron
microscopy (TEM) and atom probe tomography (APT).
However, small atomic clusters are diﬃcult to detect in
TEM, APT is unsuitable to investigate the crystallography of precipitates, and neither technique can map vacancies. Muon spin relaxation (µSR) is one techniquethat can map vacancies, and it investigates short-range
magnetic ﬁelds and the presence of point defects in solids.
This work builds upon earlier literature on aluminumwith trace elements and Al–Mg–Si alloys,3–7) and it extends the analysis to the same alloys with Cu additions.
Figure 1 shows the zero-ﬁeld µSR spectra observed forAl-1.0%Mg2 Si-0.2%Cu-AQ (in the SHTQ condition) at
measurement temperatures in the range of 20–280 K andfor Al-1.0%Mg2 Si-0.2%Cu-350C (annealed at 623 K for1000 min after SHTQ) at 280 K. The plot demonstrates
that the muon spin depolarization rate depends heavily on temperature. Similar µSR spectra were acquired
for all samples. We have interpreted the measured µSR
spectra using a Monte Carlo simulation, in which four ﬁtting parameters were employed: the dipolar width (∆),
trapping rate (νt ), detrapping rate (νd ), and fraction ofFig. 2. Fitted trapping rates from isotheral relaxation spectra. Samples are quenched after SHT and kept at 280 K
throughout the measurements. The trapping rates decrease with time for all alloys except the quaternary Al–
Mg–Si–Cu alloy, the trapping rate for which increases withtime.

initially trapped muons (P0 ).3,8)
From previous µSR studies, muons are considered to
be trapped by single vacancies or vacancy-solute pairs
near room temperature.3–6) Therefore, in most cases, theνt values decrease with time during natural aging because excess vacancies are lost at imperfections, such as
grain boundaries, voids, and surfaces. The change intrapping rate during storage at 280 K after SHTQ was
measured for Al-1.0%Mg2 Si-0.2%Cu, Al-1.6%Mg2 Si, Al0.5%Si, Al-0.2%Cu, and base Al, as shown in Fig. 2.
The horizontal axis denotes the time from SHTQ on alogarithmic scale. The νt values for the Cu-free samples decrease with time. The speed of the decrease is inversely correlated with the solute concentration, which is
expected because muons have more defects to be trappedin and more time to undergo spin relaxation. The reason
why the νt values of Al-0.2%Cu start out lower than in
the other alloys is unclear. A surprising result from theisothermal experiment is that the νt values (black circles)
for the Cu-added sample increase with time. If muons aretrapped only at vacancy-associated sites, the result indicates that the number density of vacancies increases withtime after quenching when all the elements Mg, Si, andCu are present in the alloy composition. This suggeststhat new vacancies are continuously diﬀusing into thematerial and binding to solute atoms, shifting the equilibrium concentration of vacancies to higher levels thanin the alloys with fewer elements. Further investigation
to clarify this phenomenon using positron annihilation
spectroscopy is in progress.
References

Fig. 1. Muon spin relaxation spectra for an as-quenched (AQ)
Al-1.0%Mg2 Si-0.2%Cu sample at 20–280 K and a sample
annealed at 623 K for 1000 min (350C) at 280 K.
†
∗1
∗2
∗3
∗4

Condensed from the article in Metall. Mater. Trans. A 50, 3446
(2019)
Department of Materials Science and Engineering, U. Toyama
RIKEN Nishina Center
SINTEF Industry, Norway
NTNU Norway

1) K. Matsuda et al., Mater. Trans. 58, 167 (2017).
2) M. Werinos et al., Mater. Design 107, 257 (2016).
3) S. Wenner et al., Phys. Rev. B 86, 104201 (2012).
4) S. Wenner et al., Acta. Mater. 61, 6082 (2013).
5) S. Wenner et al., Metall. Mater. Trans. A 45, 5777 (2014).
6) K. Nishimura et al., Arch. Metall. Mater. 60, 925 (2015).
7) K. Nishimura et al., J. Phys. Soc. Jpn. Conf. 21, 011030(2018).
8) T. Hatano et al., Hyper. Inter. 17, 211 (1984).

- 153 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Muon spin rotation study on the new organic spin liquid candidate
λ-(STF)2 GaCl4
T. Minamidate,∗1,∗2 D. P. Sari,∗3 N. Matsunaga,∗2 and I. Watanabe∗3
In recent research, some candidate quantum spin
liquid (QSL) materials have been found in molecular conductors such as κ-(ET)2 Cu2 (CN)3 1) and
EtMe3 Sb[Pd(dmit)2 ]2 ,2) which have antiferromagnetic(AF) spin systems with a nearly regular triangular lattice. Recently, we found a new candidate QSL material, λ-(STF)2 GaCl4 , which can be located between theorganic superconductor λ-(BETS)2 GaCl4 and the antiferromagnet λ-(ET)2 GaCl4 in the temperature-pressure
phase diagram shown in Fig. 1. The AF phase in the ET
salt is suppressed by a small pressure, and the STF salt
shows neither the AF nor the superconducting transition down to 1.6 K. The STF salt shows a gradual peakstructure in the temperature dependence of the static
susceptibility, which is well described by the AF Heisenberg model with a regular triangular lattice.3) In contrast to the good agreement of the susceptibility behavior, the calculated geometry of the spin interaction inλ-(STF)2 GaCl4 is quite distorted from a regular triangle. Therefore, it can be a key material to investigate
the stabilization mechanism of the QSL state. Hence
we conducted a µSR study to investigate the local spin
dynamics of λ-(STF)2 GaCl4 .
We succeeded in synthesizing a high-quality sampleof λ-(STF)2 GaCl4 , and in the 2017 beamtime, we conducted the ﬁrst µSR measurement. The µSR time spectrum at 0.3 K started to decouple on applying a longitudinal ﬁeld (LF) of 100 G, indicating that there is no AF
long-range ordering. However, by comparing the time
spectrum with that in an LF of 1000 G, for which thecomplete decoupling behavior was observed, we foundthat a slow relaxation remains, indicating that there are

Fig. 1. Schematic temperature-pressure phase diagram of λD2 GaCl4 (D = ET, STF, BETS).3)
∗1
∗2
∗3
∗4

RIKEN Condensed Molecular Material Lab.
Department of Physics, Hokkaido University.
RIKEN Nishina Center
Department of Physics, Sibaura Institute of Technology

Fig. 2. Temperature dependence of the µSR relaxation rate
and total asymmetry under zero field in λ-(STF)2 GaCl4 .

some eﬀects of ﬂuctuating internal ﬁelds. This behavior
is similar to that observed in the µSR measurement of
κ-(ET)2 Cu2 (CN)3 .4)
In the beamtime in July 2019, we conducted highstatistics µSR measurement and improved the experimental setup. The total asymmetry was improved incomparison with the previous experiment in 2017, from
6% to 8.3% at 0.3 K. A resonable asymmetry of about
10% is frequently observed in molecular conductors dueto the formation of muonium. The time spectra can beﬁtted by a single exponential function. Figure 2 shows
the temperature dependence of the total asymmetry andrelaxation rate λ. The total asymmetry at a high temperature was 9.3% and started to decrease below 5 K.
This decrease was not observed in the previous measurement due to unsatisfactory experimental conditions. In
conjunction, we observed the increase of λ. We now suspect that these give evidence for the gradual growth ofthe local staggered moments in the short-range AF ordered region. The lack of the transition to the bulk AF
state with the growth of the short-range order is considered to be due to static spin heterogeneity resulting fromthe disorder or due to the eﬀect of the spin frustration.
As the next step, it is important to measure the spin
dynamics toward the lower-temperature region to elucidate whether the long-range AF order or the quantum
critical point exists. Now, we have submitted a proposal
for measurement using a 3 He/4 He dilution refrigerator.
With the progress of this research, the microscopic spin
dynamics in the QSL state and the stabilization mechanism of the QSL state in a disordered system can probably be clariﬁed.
References

1) Y. Shimizu et al., Phys. Rev. B 91, 107001 (2003).
2) T. Itou et al., Phys. Rev. B 77, 104413 (2008).
3) T. Minamidate et al., J. Phys. Soc. Jpn. 84, 063704 (2015).
4) S. Nakajima et al., J. Phys. Soc. Jpn. 81, 063706 (2012).

- 154 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Zero-field µSR on single-crystal organic superconductorλ-(BETS)2 GaCl4
D. P. Sari,∗1,∗2 K. Hiraki,∗3 T. Nakano,∗4 Y. Nozue,∗5 A. Hillier,∗6 I. Watanabe,∗2 and Y. Ishii∗1
Unconventional superconductivity is often realized
in the vicinity of a magnetic ordered state, as observed in ruthenates, heavy fermions, cuprates, organic
superconductors, and Fe-based superconductors.1) In
the organic superconductor family κ-(ET)2 X with thecation molecules ET = (CH2 )2 S4 C6 S4 (CH2 )2 and anion
molecules X, the superconducting state emerges on applying pressure to the long-range-ordered antiferromagnetic insulator at a low temperature below about 10 K,
while at a high-temperature region, a crossover occurs
from a metallic to a paramagnetic insulating state.2)
Therefore, it is suspected that the metallic-state spincorrelations govern the superconductivity.
Powell and McKenzie3) proposed that for the wholefamily of organic superconductors, which includes thesystems with the β, β ′ , κ, and λ types of stacking cation
molecules in the conducting plane, the metallic spin correlations, the spin ﬂuctuations of which are maximum
near the wave vector (π, π), mediate superconductivity.
In fact, two adjacent cation molecules form a dimer are
considered as a site. Furthermore, electron hopping between a site and its nearest-neighbor sites in the transverse and longitudinal directions was described by thetransfer integrals, t, and they create a type of square lattice. The second nearest neighbor sites were then determined by the diagonal transfer integral (from upper-rightto lower-left corner of the square), t′ . Then, the so-calledanisotropic triangular lattice was characterized by the ratio, t′ /t. Accordingly, the system reached frustration att′ /t = 1. The variation from a small t′ /t (feature of thesquare lattice) passing through the frustration regime toa large t′ /t (feature of quasi-one-dimensionality) changes
the superconducting symmetry in the following manner. As the value of t′ /t is varied, the superconducting symmetry change from “dx2 −y2 ” for t′ /t < 0.93, to“(s+dxy )+i(dx2 −y2 )” for t′ ∼ t, to “s+dxy ” for t′ /t ≳ 1.3.
It should be noticed that the “(s + dxy ) + i(dx2 −y2 )”state breaks time-reversal symmetry according to themomentum-dependence plot of the argument of the complex number of the superconducting gap for several casesof t′ /t.
We focused on the study of the superconducting statein quasi-two-dimensional organic superconductor λ(BETS)2 GaCl4 with BETS = (CH2 )2 S2 Se2 C6 S2 S2 (CH2 )2through muon spin relaxation (µSR). By substituting Se
with S, which yields a negative pressure, the superconducting state eventually changed to an antiferromagnetic
state.4,5) Our transverse-ﬁeld µSR study revealed that λ∗1
∗2
∗3
∗4
∗5
∗6

Graduate School of Engineering and Science, Shibaura Institute of Tech.
RIKEN Nishina Center
Department of Physics, Fukushima Medical University
Graduate School of Science and Engineering, Ibaraki University
Department of Physics, Osaka University
ISIS Facility, STFC, United Kingdom

Fig. 1. Zero-field µSR time spectra measured at several temperatures, below and above TC of ∼5.5 K. The solid line
is a single exponential fitting model.

(BETS)2 GaCl4 has the characteristics both d-wave ands-wave pairing symmetry.6) From our calculation on thebasis of the density
functional theory of the transfer integral within BETS
dimers, λ-(BETS)2 GaCl4 has two kinds of square lattices
alternating in the a-direction. One has t′ /t ∼ 0.8, andthe other has t′ /t ∼ 0.2.7) Accordingly, the lattice is not
simple, reﬂecting its superconducting pairing symmetry.
In order to investigate the possibility of time-reversal
symmetry breaking in λ-(BETS)2 GaCl4 , we performed
zero-ﬁeld µSR in the superconducting state, which cansensitively detect the spontaneous appearance of an internal ﬁeld of the order of about 10−4 T.
We prepared ∼130 mg single crystals of λ(BETS)2 GaCl4 and oriented them all in the same direction. The polarized muon beam direction was nearly
perpendicular to the conducting plane. Zero-ﬁeld µSR
was conducted with high statistics up to 80 MEvents.
Figure 1 shows the time spectra at several temperatures
below and above the critical temperature, TC , of ∼5.5 K.
The time spectra up to 10 µs can fairly be analyzed using
a single exponential function. No appreciable change ofthe relaxation rate was detected from the measurement
at T = 6.3 K down to 1.5 K. We will perform similar
measurements in diﬀerent orientations of single crystals
with respect to the muon beam direction in order to obtain complete and precise results.
References

1) G. R. Steward, Adv. In Phys. 66, 75 (2017).
2) F. Kagawa, K. Miyagawa, K. Kanoda, Nature 436, 534 (2005).
3) Powell and McKenzie, Phys. Rev. Lett. 98, 027005 (2007).
4) Y. Saito et al., J. Phys. Soc. Jpn. 87, 013707 (2018).
5) T. Minamidate et al., J. Phys. Soc. Jpn. 84, 063704 (2015).
6) D. P. Sari, et al., in preparation.
7) D. P. Sari, RIKEN Accel. Prog. Rep. 51, 206 (2018).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Relationship between the structure and electrical conductivity of 12-mersingle-stranded polyadenine studied by scanning tunneling microscope†
H. Rozak,∗1,∗2 W. N. Zaharim,∗2 I. Miyazaki,∗3 N. E. Ismail,∗2 S. N. Abu Bakar,∗2 D. Kernain,∗5 M. R. Samian,∗4
K. Ichimura,∗3 M. I. Mohamed-Ibrahim,∗2 S. Sulaiman,∗2 and I. Watanabe∗1,∗2,∗3
DNA has received much attention over the past few
decades owing to their unique feature of π-π stacking interaction between neighboring bases. This feature provides an eﬀective medium for the electron transport process in DNA.1) In biological phenomena, the electrontransfer could be utilized to study the DNA damage andrepair mechanism at the sub-atomic scale.2)
How can we diﬀerentiate the characteristics of electron
motion in normal and damaged DNA? Furthermore, will
damage in DNA aﬀect the electron hopping rate andmechanism of electron motion? In order to answer thesequestions, ﬁrstly, we need to clarify whether DNA bases(A, C, G, and T) are conductive. Once strong baseline
data of electron transfer in each base have are accumulated, the data could be used as a reference for normal and damaged DNA. A lot of studies have been conducted in the past to investigate the electronic properties
of DNA.3) Their ﬁndings vary from insulating to semiconducting and metallic properties. In order to resolve
this matter, two main techniques were used: scanningtunneling microscopy (STM) and muon spin relaxation
spectroscopy (µSR). Measurements were performed 12mer single-stranded (12-ss) adenine, cytosine, guanine,
and thymine. But in this report, we only present the
XRD and STM data of adenine (12-ssA).
XRD measurements were performed to characterizeFig. 1. XRD patterns of 12-ssA molecules measured at room
temperature. The XRD patterns showed no sharp or enhanced diﬀraction peak, suggesting an amorphous stateof the sample.
†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Materials Science Forum. 966,
Trans Tech Publications Ltd., (2019)
RIKEN Nishina Center
School of Distance Education, Universiti Sains Malaysia
Department of Engineering, Hokaido University
School of Biological Sciences, Universiti Sains Malaysia
Institute of Research in Molecular Medicine, Universiti Sains
Malaysia

Fig. 2. The STM image of 12-ssA molecules that align in a
one-dimensional chain structure and the analysis of theheight proﬁle of 12-ssA molecules.

the structure of a 12-ssA molecules at room temperature,
however, no sharp diﬀraction peaks were observed in the
XRD pattern, which indicated that the 12-ssA sample is
not crystallized and it is in an amorphous state as shownin Fig. 1.
For the STM measurements, the molecular structureof the 12-ssA molecule was probed to measure the height
proﬁle between the tip to the sample molecule (h). This
height proﬁle represents the eﬃciency of the electron
tunneling from the tip to the sample, which could be
related to the conductivity of the sample. The relation
between the height proﬁle (h) and the eﬃciency of thetunneling current (I) could be expressed as follows:
I = V × exp[−2ℏ−1 (2mϕ)1/2 h](1)

Where m is the electron rest mass and ϕ is the work
function of the sample.4) Based on Eq. (1), the current
depends exponentially on the distance. If the distance
between tip and sample surface increase, the tunnelingcurrent decreases.
In this study, the structure of 12-ssA molecules wasfound to be well observable on the graphite substrate as
illustrated in Fig. 2. The structure of 12-ssA molecules
was observed as bright spots in the red circle. The lengthof the molecule was about 4.3 ± 1.6 Å, and the sideby-side distance was 25 ± 7.5 Å. This ﬁgure indicatesthat 12-ssA was not perfectly insulating and had electrical conductivity because STM only probe the conductive sample.5) The results of the height proﬁle of 12-ssA
molecules in Fig. 2 could be used to make a comparison
with other samples (12-ssC, 12-ssG, and 12-ssT) in the
future.
References

1) R. G. Endres et al., Rev. Mod. Phys. 76, 195 (2004).
2) M. A. Grodick et al., Biochemistry. 54, 962 (2015).
3) K. L Jiménez-Monroy et al., J. Phys. Chem. A 121, 1182
(2017).
4) T. Ohshiro et al., Chem. Commun. 46, 2581 (2010).
5) B. Bhushan, H. Fuchs, Applied Scanning Probe Methods
II. (Springer-Verlag Berlin Heidelberg, 2006).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Electron transfer in 12-mer double-stranded DNA by muon
spectroscopy and scanning tunneling microscopy
H. Rozak,∗1,∗2 S. Sulaiman,∗2 W. N. Zaharim,∗2 N. E. Ismail,∗2 S. N. Abu Bakar,∗2 M. R. Samian,∗4
I. Miyazaki,∗3 K. Ichimura,∗3 and I. Watanabe∗1,∗2,∗3
24
22
20
Asymmetry(%)

Electron transport through DNA plays a pivotal
role in biological systems. Processes that use electron transfer include scanning the damaged sites in
DNA and DNA repair.1,2) To understand these biological phenomena, it is necessary to investigate theelectron transfer process in normal and damaged DNA
at the microscopic level. The main questions of thisstudy are: what is the diﬀerence in the characteristics of electron transfer between normal and damaged
DNA, and how much the diﬀerence in the quantitative value for electron diﬀusion along the normal anddamaged DNA helix.
In order to answer those questions, muon spin relaxation (µSR) measurements were performed at theArgus spectrometer RIKEN RAL. This µSR technique
has been suggested as a good probe to study the motion of electron transfer in DNA because the muon
spin relaxation could characterize or model the diﬀusion of electrons along the DNA helix via hyperﬁneinteraction without producing any radiation eﬀect on
the sample.3)
In this study, 12-mer double-stranded synthetic
DNA GC (12 mer-dsDNA GC) was used to portraythe conditions for normal DNA. The measurements
were performed at room temperature and the external longitudinal magnetic ﬁelds were applied up to

Fig. 1. STM image of 12 mer-dsDNA GC molecules aligned
in one-dimensional chain structure.
∗1
∗2
∗3
∗4

18


 16

 14

0G
20 G
100 G
200 G
500 G
1000 G

12
10
8

0

2

4
6
Time(PS)

8

10

Fig. 2. Raw data of muon spin relaxation for 12-merdouble-stranded synthetic DNA GC dependence overtime.

3400 G. The 80 mg powder sample of 12 mer-dsDNA
GC was wrapped in a thin silver foil with the diameterof 1.5 cm.
In addition, scanning tunneling microscopy (STM)
measurements were conducted to probe the molecular
structure of 12 mer-dsDNA GC. From the STM measurements, the images of 12 mer-dsDNA GC molecules
were successfully observed as shown in Fig. 1. The
image in Fig. 1, was taken in constant current modeat room temperature and it corresponds to the surface map of electron tunneling from HOMO tip to the
LUMO of the sample.4)
Figure 2 shows the raw data of muon spin relaxation
spectra dependence over time. The asymmetry is increased as the applied magnetic ﬁeld increases. The
muon spin relaxation becomes suppressed at the highest external magnetic ﬁelds. This result indicates thatthe spin relaxation of a muon is interacting with anelectron that is rapidly diﬀusing along the molecule.
At higher applied ﬁeld, the muon-electron hyperﬁne
coupling starts to be quenched. Accordingly, the muon
spin relaxation is decreased, as illustrated in Fig. 2.
References

1) E. O’brien et al., Science 355(6327), eaag1789 (2017).
2) M. A. Grodick et al., Biochemistry 54(4), 962 (2015).
3) M. Iain, J. Phys. Chem. B 123(21), 4540 (2019).
4) R. Harison et al., Mater. Sci. Forum. 966, (2019).

RIKEN Nishina Center
School of Distance Education, Universiti Sains Malaysia
Department of Engineering, Hokkaido University
School of Biological Sciences, Universiti Sains Malaysia- 157 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53µSR study of the electron transfer mechanism of a blue copper protein,
Pseudoazurin
A. D. Pant,∗1,∗2,∗3 T. Yamaguchi,∗1 K. Ishida,∗3 and T. Kohzuma∗1Electron transfer (ET) is an important phenomenon
to understand biological processes such as photosynthesis and respiration systems. The study of ET in proteinusing positive muon was initiated by K. Nagamine’s
group with the cytochrome c protein.1) However, theelectron transfer path/mechanism is not clearly understood yet. We aim to perform a systematic study toestablish the application of muons to life science.
Since biological systems are complex in geometry
and dynamic, we started studying the ET mechanism
in a small and single active-site blue copper protein,rather than large systems. Copper proteins that containsingle- or multi-copper sites in their prosthetic group
work in a wide range of ET processes and biologicalenergy conversion cycles.2) The copper centers in these
proteins play a main role in ET. However, there remain
several obscure points in the ET pathway;3) that is,there is no clear mechanism to understand the electrontransfer. Blue copper protein (type: T1Cu) contains
only a single copper-ion binding site that serves as anelectron mediator between large proteins. Pseudoazurin(PAz), a member of T1Cu, functions in the electrontransfer processes in several microorganisms. With theapplication of the muon spin rotation and relaxation(µSR) method, we propose to probe the electron transfer mechanism in PAz, in which electron transfer occurs
only from/to the copper center. The µSR study on
PAz will provide novel insight to understand the muon
method for studies in life science.
In order to understand the ET mechanism and functions of copper proteins, we will perform µSR measurements in reduced pseudoazurin (PAzCu1+, diamagnetic) and oxidized pseudoazurin (PAzCu2+, paramagnetic) (Fig. 1) using surface muons (∼4 MeV). For
reference, a similar set of measurements will also be
performed in buﬀer solution and pure water. The samples are prepared and puriﬁed (solution, concentration∼10 mM, volume ∼700 µL) in Kohzuma laboratory,
Ibaraki University, Mito. The solution is ﬁlled in asample cell (silicone rubber ring, ϕ20 mm, t ∼ 2 mm,
polyvinylidene chloride ﬁlm ∼15 µm on both sides of
the ring), which is masked by silver ring (ϕ18 mm, t
0.3 mm) so that the incident muon beam can be prevented from stopping in the rubber. The blue oxidized
PAz changes to the reduced form using ascorbic acid.
Indium sealing is used in a helium glove bag environment. The measurements will be performed at a transverse ﬁeld of 2.3 G, zero ﬁeld, and a longitudinal ﬁeld
∗1
∗2
∗3

Institute of Quantum Beam Science, Ibaraki University
IMSS, KEK
Meson Science Laboratory, RIKEN Nishina Center

Fig. 1. Structure of pseudoazurin (PDB: 1BQK) with thecoordinate scheme around Cu(II). Copper is an active
site for electron transfer.

at diﬀerent temperature ranges (20 K–300 K).
When a surface muon beam (∼MeV) is incident on
the sample solution, the beam energy is transferred tothe solution until the end of the radiation track. A large
fraction of incident muons will be found in the diamagnetic muon form and some in the muonium form (boundstate of muon and an electron, Mu = µ+ e− ). If lowenergy muons are stopped around the copper center of
reduced PAz, there is a possibility of electron transferfrom the copper center to the muon to form Mu. The
Mu formed by the former (in solution) and latter (byelectron transfer) cases will be distinguished by theirfrequencies. Interactions will exist between muons andelectrons as well as muons and nuclei. These behaviors
are expected to be reﬂected in the time spectra. The
relaxation of Mu depends on its interaction with the environment. For example, a small amount of oxygen willcause the fast relaxation of Mu.4) The formation of Mu
at diﬀerent sites in the sample will provide information
about the electron transfer mechanism.
References

1) K. Nagamine et al., Physica B 289-290, 631–635S(2000).
2) O. Farver, Coord. Chem. Rev. 255, 757–773 (2011).
3) S. Wherland et al., Perspect. Sci. 6, 94–105 (2015).
4) A. D. Pant et al., J. Phys. Conf. Ser. 551, 012043 (2014).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 53

Temperature dependence of the total muonium emission yield fromsilica aerogel using µSR method
K. Ishida,∗1 K. Suzuki,∗2 T. Mibe,∗2 M. Iwasaki,1,∗3 S. Kamal,∗4 and J. Brewer∗4
We are developing thermal-energy muonium (Mu =µ+ e− ) production as a source of the cold muon beam forthe muon g-2/EDM experiment planned at J-PARC.1)
We observed at TRIUMF that the Mu emission ratefrom silica aerogel to vacuum is enhanced by surface
ablation.2,3) However, the present Mu yield measurement performed by tracking the muon decay positronis limited to a region away (∼5 mm) from the surface
owing to the large background from the muoniums decaying in aerogel. To enable measurement of the Mu
emitted in vacuum including the region near the surface, where we are planning to shoot a Mu ionizing
laser, we performed a new measurement using the Mu
spin rotation (MuSR) method in the ARGUS spectrometer at the RIKEN-RAL Muon Facility. In MuSR, theprecession of the muon spin can be detected by asymmetric emission of the muon decay positrons. Since theprecession frequency of Mu is diﬀerent from that of diamagnetic muon under an applied ﬁeld, we can measure
the fraction of muons forming the Mu state.
In the measurement, we added a gold foil to thedownstream of the silica aerogel target. First, we set
the muon-beam momentum so that the muons fully stopin the middle of the aerogel and measured the Mu spin
relaxation intrinsic to the aerogel material. Then, we
chose another momentum so that the muon stopping
distribution peaked at the downstream surface of the
aerogel. In this half-stopping condition, we observed
an increase in the Mu spin relaxation rate.4) This wasinterpreted as a result of Mu transfer to the gold foil
after emission to vacuum. Once in gold, Mu changes
its state to diamagnetic muon and cannot contribute to
the Mu precession signal anymore.
Here, we report the ﬁrst measurement of the temperature dependence of the Mu emission rate. In a naive
model, where Mu is emitted after diﬀusion in spacesin the aerogel nano-structure, we expect that the Mu
emission rate is proportional to the thermal Mu velocity, v ∝ T 1/2 , where T is the aerogel temperature.
Keys for the experiment are the cooling of the aerogeland the aerogel temperature measurement. Since thethermal conductivity of the silica aerogel is very low,
we relied on cooling by thermal radiation emission. We
designed a sample holder that covers all the faces of the
aerogel and mounted it on the cryostat. In a cooling test
conducted prior to the MuSR measurement, we used aK-type thermocouple directly inserted into the aero∗1
∗2
∗3
∗4

RIKEN Nishina Center
IPNS, KEK
Meson Science Laboratory, RIKEN
University of British Columbia

Fig. 1. Temperature dependence of the Mu relaxation ratewith the muons stopped in the middle (full stop) and at
the downstream edge of the silica aerogel (half stop).

gel in addition to the semiconductor thermometers on
the cryostat and the sample holder. The thermocouple
was chosen because of its small size and low heat mass.
While cooling down from room temperature, the aerogel
temperature initially followed that of the sample holder,though with some delay. Subsequently, the aerogel temperature was saturated at approximately 180 K and stabilized, however cold the sample holder was. This wasunderstood as the eﬀect of leakage of thermal radiationfrom the room-temperature surface through an opening
used to insert the thermocouple. The saturation temperature was consistent with that expected with area
fraction of the opening, which was about 10%. In the
MuSR measurement, the thermocouple was removed,
and the aerogel sample was completely surrounded by
the cold surface. This ensured that the aerogel temperature reached equilibrium with that of the holder.
A preliminary result of the Mu relaxation rate measurement is shown in Fig. 1. The relaxation rate in the
aerogel (full stop) did not change much with the temperature, while the rate in the half-stop condition waslarger and showed some temperature dependence. We
plan a detailed analysis to study whether it agrees withthe diﬀusion model assuming the Mu velocity distribution equilibrated with the temperature.
References

1) M. Abe et al., Prog. Theor. Exp. Phys. 2019, 053C02(2019).
2) P. Bakule et al., Prog. Theor. Exp. Phys. 2013, 103C01(2013).
3) G. A. Beer et al., Prog. Theor. Exp. Phys. 2014, 091C01(2014).
4) K. Ishida et al., RIKEN Accel. Prog. Rep. 52, 181 (2019).

- 159 -

3. Radiochemistry and Nuclear ChemistryⅢ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Relativistic density functional theory with the finite-light-speed
correction for Coulomb interaction†
T. Naito,∗1,∗2 R. Akashi,∗1 H. Z. Liang,∗1,∗2 and S. Tsuneyuki∗1,∗3
The periodic table of elements is determined by theelectronic conﬁguration and represents the periodicity of fundamental atomic properties. However, thepositions of super-heavy elements (SHEs) in the periodic table are tentative because their chemical properties have not been established. Owing to the shorthalf-lives of SHEs, experimental measurements of theirchemical properties are diﬃcult. Thus, ﬁrst-principles
numerical simulations are complementary tools to such
experimental measurements.
The ﬁrst-principles calculation for SHEs requires
proper treatment of the relativistic eﬀect. The relativistic eﬀect can modify the Coulomb interaction
between the charged particles, which is signiﬁcant in
SHEs. The non-relativistic form is of the order O (Zα),
whereasdominant contribution is of the or( the second)2
der O (Zα) , which is called the Breit correction.1)
Here, α ≃ 1/137 is the ﬁne-structure constant. The
Breit correction is usually called the relativistic eﬀect
or ﬁnite-light-speed eﬀect. The lowest order of relativistic eﬀects
incorporatedusing the Dirac equation
(
)
( 2)
2
is also O (Zα)∼ O 1/c . Once the relativistic
eﬀects incorporated by the Dirac equation are considered, the Breit correction between two electrons should
also be considered to keep consistency. Hereafter, we
refer to both the Breit correction and eﬀects incorporated using the Dirac equation as “relativistic eﬀect”
for simplicity.
So far, the electronic structure() calculation with therelativistic eﬀects in O 1/c2 has been performed
based on wave-function theory. In contrast, density
functional theory (DFT)2,3) with the consistent(inclu-)
sion of the relativistic eﬀects up to the order O 1/c2
is unprecedented. Although the accuracy of DFT islower than that of wave-function theory, DFT withthe relativistic eﬀects is highly desired, because DFT
is applicable to larger systems such as molecules andcoordination complex ions, the experimental synthesesof which are ongoing, and even solids.
In this paper, we formulate the Hartree-exchangecorrelation functional) for electron systems with the(correction of O 1/c2 . As a benchmark calculation,
the all-electron calculation of atoms is performed.
We calculated the energy of the lawrencium atomwith two electronic conﬁgurations, where one valence
electron occupies the 6d orbital ([Rn] 5f 14 6d1 7s2 ) or
7p orbital ([Rn] 5f 14 7s2 7p1 ). For comparison, that of
†

∗1
∗2
∗3

Condensed from the article in arXiv: 1911.10670
Department of Physics, The University of Tokyo
RIKEN Nishina Center
Institute for Solid State Physics, The University of Tokyo- 161 -

Table 1. Total energies for lutetium and lawrencium
atoms. All values are in the Hartree atomic unit.

Lu
Lr

Outermost
5d1
6p1
6d1
7p1

Non-rel−13848.19912−13848.12376−33551.48205−33551.38274

SRel-CB−14527.46807−14527.42700
Unbound−37331.31054

the lutetium atom is also calculated, where one valence
electron occupies the 5d orbital ([Xe] 4f 14 5d1 6s2 ) or
6p orbital ([Xe] 4f 14 6s2 6p1 ). The energies calculatedwith these conﬁgurations in the non-relativistic (Nonrel) and the newly-developed relativistic (SRel-CB)
schemes are listed in Table 1. The smaller values forthe respective approximations in each atom are written
in bold. In the lutetium atom, the outermost valence
electron prefers to occupy the d orbital rather than the
p orbital with all schemes. In contrast, in the lawrencium atom, the electron prefers to occupy the p orbital
rather than the d orbital with the SRel-CB scheme,
whereas it still prefers the d orbital in the Non-rel
scheme, as in the lutetium case. The occupation of thep orbital could be the origin of the anomalous behaviorof lawrencium.4) This result is consistent with previous calculations using wave-function theory.5,6) Notethat we obtained the consistent results with far lesscomputational cost than those previous calculations.
It should also be noted that the p-block elements aredeﬁned as those in which the outer-most electrons occupy the p orbitals.7) Lawrencium, thus, belongs to
the p block, rather than d according to the deﬁnition.
It seems, however, more appropriate to regard thatthe concept of “block” is ambiguous for the heavy andsuper-heavy elements, because the electronic conﬁguration of lawrencium is almost the same as that oflutetium, and the only diﬀerence is in the outermost
electron. Therefore, reconsideration of the classiﬁcation appropriate for SHEs is mandatory.
References
1) G. Breit, Phys. Rev. 34, 553 (1929). ibid 36, 383 (1930).
2) P. Hohenberg, W. Kohn, Phys. Rev. 136, B864 (1964).
3) W. Kohn, L. J. Sham, Phys. Rev. 140, A1133 (1965).
4) T. K. Sato et al ., Nature 520, 209 (2015).
5) E. Eliav, U. Kaldor, Y. Ishikawa, Phys. Rev. A 52, 291(1995).
6) X. Cao, M. Dolg, H. Stoll, J. Chem. Phys. 118, 487(2003).
7) F. A. Cotton, G. Wilkinson, P. L. Gauss, Basic Inorganic Chemistry (John Wiley & Sons, 1995).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

On-line anion-exchange experiment of Nb and Ta in HF/HNO3 mixture
solution for Db chemistry
S. Adachi,∗1,∗2 A. Toyoshima,∗1,∗3 K. Tsukada,∗1,∗4 H. Haba,∗1 Y. Komori,∗1 T. Yokokita,∗1 Y. Shigekawa,∗1
Y. Wang,∗1 A. Kashihara,∗1,∗2 M. Kato,∗1,∗5 A. Nakajima,∗1,∗5 and K. Sueki∗1,∗6
Superheavy elements with atomic number ≥ 104 areplaced at the 7th period of the periodic table. Owing
to the inﬂuence of strong relativistic eﬀects caused bytheir large positive nuclear charge, these elements are expected to have chemical properties diﬀerent from thoseof lighter homologues. However, because these elements
have very short half-lives and low production rates in nuclear reactions, it is diﬃcult to determine their chemical
properties.
Few studies on the aqueous chemistry of Db, a group5 superheavy element, have been performed together
with the lighter homologues Nb and Ta and the pseudohomologue Pa. In the anion exchange in 13.9 M HF
solution, the distribution coeﬃcient (Kd ) of Db was reported to be smaller than those of Nb and Ta but larger
than that of Pa.1) In 0.31 M HF/0.1 M HNO3 solution, the adsorption of Db on the resin was showed to
be clearly weaker than that of Ta and similar to thoseof Nb and Pa.2) These studies suggest that Db would
form [DbOF4 ]− like Nb or [PaOF5 ]2− and/or [PaF7 ]2−
like Pa, but not [DbF6 ]− like Ta. Thus, the purpose of
the present study is to investigate whether Db behaves
like either Pa or Nb, particularly in high HF concentrations, which would enable us to deduce its chemical
form: [DbOF4 ]− or [DbF6 ]− . In this study, we performed on-line anion-exchange experiment of Nb and Ta
in HF/HNO3 mixture solution by using an automatedrapid chemistry apparatus (ARCA) to determine thesuitable experimental conditions for Db.
88g
Nb (T1/2 = 14.5 min) and 170 Ta (T1/2 = 6.7 min)were produced in the nat Ge(19 F, nx) and nat Gd(19 F, nx)
reactions, respectively, using the RIKEN K70 AVF
cyclotron. The reaction products transported by a
He/KCl gas-jet system were deposited on a collection

Fig. 1. Elution curves of 88g Nb and 170 Ta in 0.20, 11, 14.5 M
HF/1.0 M HNO3 solutions.
∗1
∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Graduated school of Pure and Applied Sciences, Tsukuba University
Institute for Radiation Sciences, Osaka University
JAEA Advanced Science Research Center
Science and Engneering, Tsukuba University
Faculty of Pure and Applied Sciences, Tsukuba University

Fig. 2. Variation of the distribution coeﬃcient, Kd , of Nb,
Ta, and Pa as a function of [F− ].

site of ARCA. Then, the products were dissolved in 0.1–
14.5 M HF/1.0 M HNO3 mixture solution. The solution
was fed onto a small chromatographic column (1.6 mm
i.d. × 7 mm) ﬁlled with anion-exchange resin (MCI GELCA08Y) at a ﬂow rate of 1.0 mL/min. The eﬄuent fractions were collected in 7 polypropylene tubes. The products remaining in the column were stripped with 0.015 M
HF/6.0 M HNO3 mixed solution and were collected inanother PP tube. These fractions assayed by γ-ray spectrometry with a Ge detector to obtain elution curves for
Nb and Ta.
Figure 1 shows, the elution curves of 88g Nb and 170 Ta
in 0.20, 11, and 14.5 M HF/1.0 M HNO3 solutions.
The eluted radioactivity A(ν) at eﬄuent volume ν is expressed by the the{following equation: }(1)
A(ν) = Amax −N (νp − ν)2 /(2νp ν))
where Amax , N , and νp are maximum peak height, thenumber of theoretical plates, and the peak volume, respectively. The ν and νp values are corrected for thedead volume. The results of the ﬁt are in good agreement with the experimental data. The Kd value basedon the column chromatographic method is expressed as
Kd = νp /mr(2)
where mr is the mass of dry resin. The average mr value
was measured to be 5.7±0.6 mg. The Kd values obtained
through the online column chromatography and a batch
experiment conducted separately are plotted in Fig. 2.
The Kd values in the on-line experiment are larger
than those in the batch experiment. However, the overall trend of Kd values, such as a sudden increase in theKd value of Nb at around [F− ]eq = 5 × 10−3 M, was reproduced. This suggests that the anion-exchange kinetics of Db may be fast in the present mixed solution, andthe Kd values of Db may be obtained under the present
conditions. In the near future, we will perform online
experiments of Db to determine its Kd value.
References

1) K. Tsukada et al., Radiochim. Acta 97, 83 (2009).
2) Y. Kasamatsu et al., Chem. Lett. 38, 1084 (2009).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Anion-exchange behaviour of Nb, Ta and Pa in H2 SO4
M. Kato,∗1,∗2 K. Tsukada,∗3 H. Haba,∗1 Y. Komori,∗1 T. Yokokita,∗1 D. Mori,∗1 S. Adachi,∗1,∗4
A. Kashihara,∗1,∗4 and K. Sueki∗1,∗5
Studies on the behavior of the group-4 elements Zr
and Hf, which are homologous elements of Rf, havebeen conducted in H2 SO4 .1) It was found that the ionexchange reaction of Zr and Hf is slow in H2 SO4 andcannot reach equilibrium in current superheavy element studies. On the other hand, there are not many
researches on the group-5 elements in H2 SO4 . Similarly to the group-4 elements, the ion-exchange reaction of the group-5 elements Nb and Ta, and theirpseudo homologue Pa may be slow. To elucidate thebehaviour of Db in H2 SO4 , it is necessary to clarify the
behaviour of Nb, Ta and Pa in H2 SO4 .
95
Nb (T1/2 = 35.0 d) and 179 Ta (T1/2 = 1.82 y) were
produced in the nat Zr(d, xn) and nat Hf(d, xn) reaction,
respectively, by bombarding metallic nat Zr and nat Hf
foils with a 24-MeV deuteron beam using the RIKEN
AVF cyclotron.
Each target material was dissolved in 0.2 mL ofconcentrated HF solution in a PTFE beaker. After evaporation to dryness, the residue was dissolved
with 0.2 mL of 1 M HF and then dried up. The
residue was dissolved with 0.3 mL of 1 M HF and fed
onto a chromatographic column ﬁlled with the anionexchange resin (BIO RAD AG 1 × 8 100–200 mesh,F− form 5 mm i.d. × 45 mm). After washing the column with 2.5 mL of 1 M HF, Zr and Hf were eluted
from the column with 5 mL of the mixed solution of
9 M HCl/0.004 M HF. Then, Nb was eluted with 5 M
HNO3 /0.2 M HF, while Ta was eluted with 4 M HCl.2)
233
Pa (T1/2 = 27.0 d) was chemically separated from237
Np (T1/2 = 2.144×106 y). 237 Np was dissolved with
0.2 mL of 9 M HCl, and fed onto the chromatographic
column ﬁlled with the 100–150 mesh of the TK400
resin. Np was eluted with 20 mL of 9 M HCl, then
Pa was eluted subsequently with 1.8 mL of 1 M HCl.
The solution was evaporated to dryness to fume out
HCl. Then, the residue was dissolved with pure waterand evaporated to dryness 3 times. Then, radio tracers
were stocked in a polypropylene vessel in 1 M H2 SO4 .
For the batch experiments with low H2 SO4 concentrations, the radiotracer was diluted to 0.2 M H2 SO4 withpure water.
The anion-exchange resin used was the strongly
basic anion exchanger, MCI GEL CA08Y suppliedby Mitsubishi Chemical Corporation. The resin waswashed with 2.0 M NaOH and 2.0 M H2 SO4 alterna∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Science and Engineering, University of Tsukuba
JAEA, Advanced Science Research Center
Graduated school of Pure and Applied Sciences, Universityof Tsukuba
Faculty of Pure and Applied Sciences, University of Tsukuba- 163 -

Fig. 1. Variation of the Kd values of 95 Nb, 179 Ta and 233 Pa
on the anion-exchanger CA08Y as a function of HSO−
4
concentration [HSO−
4 ].

tively 3 times to replace Cl− ion in CA08Y with HSO−
4.
Finally, the resin was washed with distilled water anddried up to a constant weight at 70◦ C in an oven.1)
We determined the distribution coeﬃcient (Kd ) values of Nb, Ta, and Pa on CA08Y in H2 SO4 at various concentrations. 5–25 mg of the resin and 3 mLof H2 SO4 solutions with 50 µL of the radiotracer wereplaced in a polystyrene centrifuge tube and shaken for
120 min at 22◦ C. After centrifugation, a 1 mL of thesolution was pipetted and subjected to γ-ray spectrometry with a Ge detector The same treatment was conducted without the resin to determine the reference radioactivity. The radioactivity on the resin was determined by subtracting the solution radioactivity fromthe reference activity.
Figure 1 shows a variation of the Kd values of Nb,
Ta, and Pa as a function of [HSO−
4 ]. Especially in thecase of Nb, the Kd values varies greatly. Therefore, it’snecessary to check the reproducibility of the data.
It was reported that the ion-exchange reaction of thegroup-4 elements is slow.1) However, we found that thereaction of the group-5 elements reach the equilibrium
faster, within 20 s.
References

1) Z. J. Li et al., Radiochim. Acta 100, 157 (2012).
2) Y. Kasamatsu et al., J. Nucl. Radiochem. Sci. 8, 2
(2007).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Anion exchange of Nb and Ta in HF/HCl mixture solution for Db
chemistry
T. Yokokita∗1 and H. Haba∗1

105

Kd / mL g–1

10[F––] =10–3
M–5[F ] =10 M

4

–

–4

[F ] =10

M

103
102
101
100

0.01

0.1
[Cl–] / M

RIKEN Nishina Center[F–] =10–3 M[F–] =10–5 M

105[F–] =10–4 M

104
103
102

0.01

0.1
[Cl–] / M

1

Fig. 2. Kd values of Ta in anion exchange as a function of
Cl− concentration.

following equation:
Kd = Ar Vs /As wr = (Ac − As )Vs /As wr ,(1)

where Ar and As are the radioactivities on the resin andin the solution, respectively; Vs is the volume (mL) of
the solution; and wr is the mass (g) of the dry resin. Ac
denotes the radioactivity of the control solution.
The Kd values of Nb and Ta as a function of Cl− concentration in the anion-exchange experiment are shownin Figs. 1 and 2, respectively. The values of Nb andTa linearly decrease with increasing Cl− concentration,
except for Nb in [F− ] = 10−5 M. These results suggestthat Nb and Ta form anionic complexes in [F− ] ≥ 10−4
and ≥10−5 M, respectively. The slope values between
log Kd and log [Cl− ] of Nb are −1.1 ± 0.1 and −1.3 ± 0.1
in [F− ] = 10−4 and 10−3 M, respectively. These results
indicate that the net charge of the adsorbed Nb species
is −1. For Ta, the slope values between log Kd and log[Cl− ] are −0.8 ± 0.1, −0.4 ± 0.1, and −0.8 ± 0.4 in [F− ]= 10−5 , 10−4 , and 10−3 M, respectively. These results
indicate that the net charge of the adsorbed Ta species
is −1 at [F− ] = 10−5 and 10−3 M. However, at [F− ] =10−4 M, the net charge of the adsorbed Ta species cannot
be determined.
We also obtained the Kd values of Nb and Ta as afunction of F− concentration in [HCl] = 0.1 M. We also
obtained those of Pa in our previous study.4) The sequence of the Kd values is Ta > Nb > Pa, and it is consistent with that in the HF/HNO3 mixture system.2,3)
This point suggests that the eﬀect of the chloride ion issmall for the complexation agent. On the other hand,another study is needed to check the eﬀect of chloride
ion.
References

1Fig. 1. Kd values of Nb in anion exchange as a function of
Cl− concentration.
∗1

106

Kd / mL g–1

Clarifying the chemical properties of superheavy elements with atomic number (Z) ≥ 104 is an intriguing
and important subject. These elements are produced ataccelerators using heavy-ion-induced nuclear reactions.
The production rates of these elements are low, and theirhalf-lives are short (T1/2 ≤ 1 min). Thus, chemical studies on these elements are conducted on a single-atombasis.1)
The ﬂuoride ion is a very strong complexing agent forgroup-5 elements (Nb and Ta). The ﬂuoride complex
species of the heaviest group-5 element, dubnium (Db),
is very interesting (Db forms oxyﬂuoride or ﬂuoride complexes) because Nb and Ta form diﬀerent ﬂuoride complexes (Nb: [NbOF5 ]2− ; Ta: [TaF7 ]2− ) in 0.1–10 M HF([F− ] = 8.9 × 10−3 − 1.9 × 10−2 M).2) To determine theﬂuoride complex species of Db, we plan to perform an
ion-exchange study of Db. In this study, we performed
an anion-exchange experiment on Nb and Ta in HF/HClmixture solutions to determine the suitable experimental
conditions and obtain comparable data for Db.
We produced 95 Nb and 179 Ta in the nat Zr(d, xn)
and nat Hf(d, xn)179 Ta reactions (nat = natural isotopic
abundance), respectively, by using the RIKEN AVF
cyclotron. These radiotracers were puriﬁed by theanion-exchange method using the procedure reported inRef. 3).
In the anion-exchange experiments, the anionexchange resin (MCI GEL CA08Y) was added to 0.25 mLof an HF/HCl mixture solution containing both 95 Nb
and 179 Ta in a PP tube, and the mixture was shaken using a mixer. Next, the resin was removed by centrifugation. Subsequently, the ﬁltrate was pipetted into anothertube, weighed, and subjected to γ-ray spectrometry using a Ge detector. The concentration of HF and HCl
was determined by titration with a standardized NaOH
solution before the experiments. In all anion-exchange
experiments, control experiments without the resin were
performed. The Kd values were determined from the1) A. Türler, V. Pershina, Chem. Rev. 113, 1273 (2013).
2) Y. Kasamatsu et al., J. Radioanal. Nucl. Chem. 279, 371(2009).
3) Y. Kasamatsu et al., J. Nucl. Radiochem. Sci. 8, 69 (2007).
4) T. Yokokita, H. Haba, RIKEN Accel. Prog. Rep. 52, 186(2019).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Anion exchange of element 104, Rf, at 0.11 M H2 SO4 by usingbatch-type solid-liquid extraction apparatus, AMBER
T. Yokokita,∗1 Y. Kasamatsu,∗2 E. Watanabe,∗2 Y. Komori,∗1 Y. Shigekawa,∗1 Y. Wang,∗1 D. Mori,∗1
H. Ninomiya,∗2 S. Hayami,∗2 K. Tonai,∗2 K. Ghosh,∗1 A. Shinohara,∗2 and H. Haba∗1
The relativistic eﬀect of orbital electrons is relatively more pronounced for heavy elements. In particular, the chemical properties of superheavy elements(SHEs) with atomic number Z ≥ 104 are expected deviate from the periodicity of their lighter homologues
in the periodic table. Thus, it is important and interesting to investigate the chemical properties of these elements. Thus far, ion-exchange experiments on SHEs
have been conducted to determine the distribution coeﬃcients (Kd ), which are deﬁned as the ratio of the elemental concentrations of the two phases.1) However,those values at equilibrium have not been obtained inmost studies. To obtain the Kd values for Rf at equilibrium, a batch-type solid-liquid extraction apparatus
called AMBER was developed,2) and the equilibrium
Kd values on the chloride complexation of Rf were successfully obtained in an Aliquat 336/HCl system.3)
To study the sulfate complexation of Rf, we planto perform anion-exchange experiments with Rf andits homologous elements. By using AMBER, we havealready performed online anion-exchange experimentswith Zr and Hf in H2 SO4 as the model experiments
for Rf and determined the anion-exchange experimental condition of Rf as 0.1–0.7 M H2 SO4 .4) In this work,
we performed online anion-exchange experiments with
Rf and Hf at 0.11 M H2 SO4 by using AMBER to examine the equilibrium time for the distribution of theelements and determine their Kd values.
In the online anion exchange of Rf and Hf, we simultaneously produced 261 Rf and 169 Hf (T1/2 = 3.24 min)by the bombardment of a mixture of 248 Cm and nat Gd
mixture with 18 O beams delivered by the K70 AVF
cyclotron at RIKEN. The products were transported
to a chemistry room by a He/KCl gas-jet system. The
transported products were deposited on the collection
site of AMBER’s dissolution equipment for ∼3 min
and were dissolved with 0.24 mL of 0.11 M H2 SO4 .
The solution sample was injected into a chemical reaction container containing the anion-exchange resin(MCI GEL CA08Y). After shaking the container witha shaker for 10, 30, and 90 s, only the solution phase
was discharged from the container, after being passed
through a PTFE ﬁlter by compressed air for 10 s. The
discharged solution was collected in a Ta disk on theround table of an automated rapid α/SF detection system5) and evaporated quickly to dryness using hot He
gas and a halogen heat lamp. Subsequently, using thedetection system’s robot arm, the Ta disk was sub∗1∗2

RIKEN Nishina Center
Graduate School of Science, Osaka University- 165 -

jected to rapid γ-ray measurement with a Ge detector
to monitor 169 Hf. We also performed control experiments with 10-s shaking without the resin to determine
the standard radioactivity of the solution sample. The
Kd values were determined from the radioactivities in
the resin and solution phases, the volume of the solution phase, and the mass of the dry resin.
We conducted 327 anion-exchange and 135 control
cycles, and observed a total of 96 α events from thedecay of 261 Rf and its daughter nuclide 257 No (T1/2 =24.5 s), including 14 time-correlated α-α correlations.
The event ratios of 261 Rf between the resin and solution phases were estimated from the α events. The Kdvalues of Hf were constant in all the time ranges studied (10–90 s), indicating that equilibrium in the anion
exchange of Hf was accomplished within 10 s. Thoseof Rf were also constant in all the time ranges studied,yielding values of approximately 10 mL g−1 . This indicates that Rf is not adsorbed on the resin. In turn, thisis considered to suggest that Rf does not form an anionic sulfate complex at 0.11 M H2 SO4 , though there is2−
a possibility that counter ions of HSO−
4 and SO4 are
preferentially adsorbed on the resin. It should be notedthat that we cannot exclude the possibility that the kinetics of Rf is signiﬁcantly slower than that of Zr and
Hf. The Kd values at 0.1 M H2 SO4 follow the order of
Zr > Hf ≫ Rf, and this sequence is consistent with thetrend predicted by theoretical calculation.6) Furthermore, in a cation-exchange study in H2 SO4 /HNO3 , thesequence of the Kd values was reported to be Rf > Hf
≥ Zr.7) These results indicate that the sulfate complexation of Rf is weaker than those of lighter homologues.
From the present work, we found that Rf is not adsorbed on the anion-exchange resin at 0.11 M H2 SO4within 10–90 s. However, it is not clear whether Rf
avoids forming the anionic sulfate complex in this studied condition. We need additional anion-exchange experiments of Rf at a lower counter-ion concentration.
References
1) Y. Nagame et al., Nucl. Phys. A 944, 614 (2015).
2) Y. Kasamatsu et al., Radiochim. Acta 103, 513 (2015).
3) T. Yokokita et al., Dalton Trans. 45, 18827 (2016).
4) T. Yokokita et al., RIKEN Accel. Prog. Rep. 52, 187(2019).
5) H. Haba et al., RIKEN Accel. Prog. Rep. 45, 204 (2012).
6) V. Pershina et al., Radiochim. Acta 94, 407 (2006).
7) Z. J. Li et al., Radiochim. Acta 100, 157 (2012).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Anion exchange of Zr, Hf, and Th by the automated extraction
apparatus: toward the chemical study of 104 Rf in HNO3
E. Watanabe,∗1 T. Yokokita,∗2 Y. Kasamatsu,∗1 S. Hayami,∗1 K. Tonai,∗1 Y. Shigekawa,∗2 H. Haba,∗2 and
A. Shinohara∗1
Chemical elements with Z ≥ 104 are called superheavy elements (SHEs). The chemical properties ofSHEs are almost unknown because they must be synthesized by heavy-ion-induced nuclear reactions using
accelerators with very low cross sections and have very
short half-lives (T1/2 ≤ 1 min). There are some chemical
experiments on 104 Rf in solution chemistry; however, its
chemical properties are not suﬃciently understood due
to limited experimental methods. Further systematic experimental studies are needed. In our previous work, wedeveloped the automated batch-type solid-liquid extraction apparatus (AMBER) and investigated the anionexchange behavior of Rf in HCl and H2 SO4 to obtain
the distribution coeﬃcients (Kd ) of Rf under chemical
equilibrium conditions.1,2)
In this study, we focus on the formation of the Rf nitrate complexes. Indeed, the clear diﬀerence between
the complexation of Th (pseudo homologue of Rf) andthose of Zr and Hf (homologues) in HNO3 is known; Th
forms an anionic complex with large coordination numbers of 10 and/or 12, while Zr and Hf do not. We previously found that anion-exchange reactions using Adogen464 resin (anion exchanger) in HNO3 reach the chemical
equilibrium in 60 s for Th, and this resin is promisingfor 261 Rf (T1/2 = 68 s) experiments. Toward the anionexchange experiments of Rf in HNO3 using AMBER,
herein, we determined the experimental conditions forwashing the resin and its repetitive use.
We produced the 88 Zr and 175 Hf isotopes in the89
Y(d, 3n) and nat Lu(d, xn) reactions, respectively, byusing the RIKEN AVF cyclotron. 234 Th was separated
from 238 U (α-decay mother nuclide). These radionuclides were puriﬁed by an anion-exchange method.
0.3 mL of 8 M HNO3 including 88 Zr, 175 Hf, and 234 Th
was injected into the chemical reaction container in AMBER, containing 3 mg of the Adogen 464 resin, and thecontainer was shaken for 60 s (anion-exchange part). After only the solution phase was discharged from the container passing through a PTFE ﬁlter with compressed
air, the Zr, Hf, and Th adsorbed on the resin were
washed out by injecting 0.1 M HNO3 or 0.1 M HCl into
the container (back extraction part). In the same manner as above, the washing solution was discharged fromthe container. This part was repeated until all of Zr, Hf,
and Th were excluded from the resin. The recovery rateuntil the m-th back extraction was determined from thefollowing equation:
R(m) =

m
∑
i

∗1
∗2

Ai /

n
∑

Ai ,

i

Graduate school of Science, Osaka University
RIKEN Nishina Center

Fig. 1. Recovery rate R(m) of Zr, Hf, and Th using 0.1 M
HNO3 and 0.1 M HCl as the back extractant.

where Ai is the radioactivity of the solution in the ith back extraction, and n is the total number of backextraction.
Figure 1 shows the behavior of R(m) as a function ofm. This graph shows that 9 or 10 times of back extractions are required to wash out all of the Zr, Hf, and Th
adsorbed on the resin in 0.1 M HNO3 (a), while 3 or
4 times are enough in 0.1 M HCl (b). This diﬀerence
results in diﬀerent experimental times for one cycle (thetotal time of anion-exchange part, back extraction part,and conditioning part); 5 min for 0.1 M HNO3 (9 backextractions), and 3 min for 0.1 M HCl (3 back extractions). We decided to use 0.1 M HCl as the solution forback-extraction since the experiments for 261 Rf shouldbe performed in shorter cycles.
We performed about 100 cycles of the following sequence; 60 s of anion exchange with 8 M HNO3 , followedby 4 back extractions with 0.1 M HCl, and then 2 iterations of conditioning with 8 M HNO3 . The Kd valuesof Zr, Hf, and Th in the anion exchange were constantin 100 consecutive runs using AMBER, and this result
indicates that the Adogen 464 resin has suﬃcient durability to conduct a repetitive anion-exchange experimentof 261 Rf.
In the near future, an on-line experiment of Zr and Hf
will be conducted as a model experiment for Rf underthe experimental conditions determined in this study.

(1)
References
1) T. Yokokita et al., Dalton Trans. 45, 18827 (2016).
2) T. Yokokita et al., RIKEN Accel. Prog. Rep. 52, 187 (2019).
- 166 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry99

RIKEN Accel. Prog. Rep. 53

Ru and 57 Fe Mössbauer spectroscopic studies of Na2 Ru1−x Fex O3 of
sodium-ion battery electrodeK. Hamano,∗1,∗2 Y. Kobayashi,∗1,∗2 H. Haba,∗2 and H. Ueno∗2∗1∗2

Dep. of Eng. Sci., University of Electro-Commun.
RIKEN Nishina Center- 167 -

1.01

Relative transmission (a. u.)

1
0.99
0.98
0.97
0.96
0.95
0.94
0.93
0.92
-4

-3

-2

-1

0

1

2

3

4

Velocity mm/

Fig. 1. 57 Fe Mössbauer spectrum of disordered
Na2 Ru0.99 Fe0.01 O3 measured at 15.0 K.
1.001

Relative transmission (a. u.)

Sodium-ion batteries have attracted attention as thenext generation of batteries after Li-ion batteries forlarge-scale applications owing to the abundance andlow cost of sodium.1–3) The use of Na-excess metal oxides, Na2 MO3 (M: transition metals), as cathode materials may realize large capacities through an additional
oxygen redox reaction. Among Na-excess metal oxides,
Na2 RuO3 is expected to be the leading cathode material. In this study, we demonstrate the oxidation states
and coordination environments of Ru ions in Na2 RuO3
and Na2 Ru1−x Fex O3 (x = 0.01 and 0.05) after repeating the charge/discharge processes by means of 99 Ru
and 57 Fe Mössbauer spectroscopy, XRD, and electrochemical measurements. Mössbauer spectroscopy is a
powerful tool to understand the oxidation states of
Ru ions. However, the measurements of 99 Ru Mössbauer spectra can only be performed at low temperatures because the Mössbauer transition energy is relatively high (Eγ = 89.8 keV).4,5) A 57 Fe-doped sampleof Na2 Ru1−x Fex O3 was prepared to estimate the temperature dependence of the oxidation states of Ru sites
by 57 Fe Mössbauer spectroscopy.
Na2 RuO3 has a layered structure in which the ﬁrst
layer is composed of Na+ and the second layer contains Na+ and Ru4+ in the ratios 1:3 and 2:3, respectively. It is known that Na2 RuO3 has two phases,
namely, ordered and disordered arrangements, whichcorrespond to sintering times of 48 h and 12 h, respectively. Ordered Na2 RuO3 has honeycomb-type cation
ordering in the [Na1/3 Ru2/3 ]O2 layers, whereas disordered Na2 RuO3 has a random distribution of Na+ andRu4+ in the [Na1/3 Ru2/3 ]O2 layers. The two polymorphs exhibit signiﬁcant diﬀerences in electrochemical properties.3)
A sample of disordered Na2 Ru0.99 Fe0.01 O3 was prepared through a solid-state reaction. A stoichiometricmixture of RuO2 , NaHCO3 , and Fe2 O3 was pressedand sintered at 850◦ C for 12 h in an Ar atmosphere.
The Na2 Ru0.99 Fe0.01 O3 sample was conﬁrmed to be
in a single phase by XRD. For 99 Ru Mössbauer spectroscopy, the source nuclide 99 Rh (T1/2 = 15.0 d) was
produced through the 99 Ru(p, n)99 Rh reaction at the
AVF Cyclotron. 99 Ru Mössbauer spectra were obtained by a conventional arrangement, but both thesource and absorbers were maintained at 4.2 K in aliquid He cryostat during the measurements.
The 57 Fe Mössbauer spectrum of disordered
Na2 Ru0.99 Fe0.01 O3 shows a doublet peak, as shown in
Fig. 1. The doublet was analyzed with the distribu-

1

0.999

0.998

0.997

0.996

0.995
-4

-3

-2

-1

0

1

2

3

4

Velocity mm/

Fig. 2. 99 Ru Mössbauer spectrum of disordered
Na2 Ru0.99 Fe0.01 O3 measured at 5.0 K.

tion of quadrupole splitting (∆EQ ) because Fe ionswere randomly present at on Na and Ru sites. The
mean values of the obtained distributions of the isomer
shift (δ) and ∆EQ were 0.48(1) mm/s and 0.64 mm/s,
respectively. Fe ions were in a trivalent state in the[Na1/3 Ru2/3 ]O2 layers. The 99 Ru Mössbauer spectrum shows a broadened and asymmetric single line, as
shown in Fig. 2. The isomer shift was −0.30(1) mm/s,
and the Ru ion was in a typical Ru4+ state. It is speculated that the line broadening is caused by an increasein the oxidation state of a part of the Ru ions from
Ru4+ to Ru5+ and a signiﬁcant distortion of the octahedron of RuO6 with the introduction of a Fe3+ ion.
References

1) K. M. Mogare et al., Z. Anorg. Allg. Chem. 630, 547 (2004).
2) M. Tamaru et al., Electrochem. Commun. 33, 23 (2013).
3) B. M. de Boisse et al., Nature Commun. 7, 11397 (2016).
4) K. Takahashi et al., RIKEN Accel. Prog. Rep. 48, 242(2015).
5) Y. Kobayashi et al., J. Phys. 217, 012023 (2010).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Development of an RF-carpet gas cell for the chemistry of superheavy
elements
Y. Shigekawa,∗1 A. Yamaguchi,∗2 N. Sato,∗1 A. Takamine,∗1 M. Wada,∗3 and H. Haba∗1
The chemical investigation of superheavy elements(SHEs), with atomic number Z ≥ 104, is intriguing because of the strong relativistic eﬀects on atomic electrons.1) In previous studies, the gas-phase chemical properties of SHEs up to Hs (Z = 108) and those of Cn(Z = 112), Nh (Z = 113), and Fl (Z = 114) have beenmeasured1) with the help of the He gas-jet system, whichallows the deceleration and rapid transport of produced
SHEs to gas chromatographic apparatus. However, forthe heaviest elements such as Cn, Nh, and Fl, reliable experimental data with suﬃcient statistics have not beenobtained, because of their short half-lives (∼1 s), which
are shorter than the transportation time of the He gas-jet
system (∼3 s). The RF-carpet gas-cell system, currently
used for precise mass measurements of transfermium elements,2,3) allows the rapid deceleration and transportation (<100 ms) of SHE ions separated with a gas-ﬁlled
recoil ion separator (GARIS-II). In this study, we developed a cryogenic RF-carpet gas cell, placed after GARISor GARIS-II and connected to a gas chromatographic apparatus, for the gas-phase chemistry of short-lived SHEs(<3 s).
Figure 1 shows a schematic view and photograph ofthe constructed gas cell, which is similar to the one being
used in the SHE-Mass-II.3) A gas-cell chamber, where He
gas for decelerating SHE ions is introduced, is supported
by a cryocooler inside a vacuum chamber. The cryocooler can cool the gas cell to ∼70 K, freezing gaseous
impurities and preventing SHE ions from reacting with
impurities. A DC cylinder and an RF carpet are placed
inside the gas-cell chamber. The DC cylinder, consistingof 45 electrodes connected by low-outgas surface-mountresistors, produces a drift ﬁeld of up to ∼9 V/cm fortransporting SHE ions to the RF carpet. The RF carpet
consists of many concentric-ring electrodes with 60-µm
width and 100-µm spacing. It has a Φ0.32-mm hole atthe center for extracting SHE ions. The hole diameteris less than that of SHE-Mass-II (Φ0.74 mm), allowing
a lower pressure in the vacuum chamber and lower loss
rate of He gas from the gas-cell chamber. A quadrupole(a)Vacuum (b)chamber

Cryocooler

DC cylinder RF carpet

DC cylinder
QPIG

SHE ion from GARIS
260 mmGas cellchamberCs+ source

RF carpet

190mm

Cs+ source

200 mmFig. 1. (a) Schematic view and (b) photograph of the developed cryogenic RF carpet gas cell.
∗1
∗2
∗3

RIKEN Nishina Center
Quantum Metrology Laboratory, RIKEN
Wako Nuclear Science Center (WNSC), IPNS, KEK

Fig. 2. Transportation eﬃciency of Cs+ ions as a function of
the RF voltage for combinations of the AF frequency andvoltage with a drift ﬁeld of 6.7 V/cm at a He pressureof 100 mbar and a gas-cell temperature of approximately
75 K.

ion guide (QPIG) is placed close to the hole of the RF
carpet to transport extracted ions.
As an evaluation of the apparatus, we measured thetransportation eﬃciency of Cs+ ions from the surface of
the RF carpet to the central hole of the carpet by usinga Cs ion source placed inside the gas-cell chamber. First,
the current of Cs+ ions that reached the RF carpet wasmeasured using the carpet as the Faraday cup. Next,
Cs+ ions were transported towards the carpet hole byapplying RF ﬁelds, on which audio frequency (AF) ﬁelds
were superimposed,4) to the carpet. The current of Cs+ions extracted through the hole was measured using the
QPIG as the Faraday cup. The transportation eﬃciency
was obtained by dividing the current at the QPIG bythat at the RF carpet.
Figure 2 shows an example of the measured transportation eﬃciency as a function of the RF voltage. For
each AF frequency, the AF voltage was ﬁxed to the valuethat could maximize the transportation eﬃciency. In
Fig. 2, the transportation eﬃciency is saturated withhigh RF voltages, indicating that suﬃcient RF voltages
can be applied to the RF carpet with our setup. Highmaximum transportation eﬃciencies (more than 80%)
were successfully obtained; hence, the constructed gas
cell would be applicable to experiments with SHE isotopes at low production rates. Higher AF frequencies
are preferable in that lower RF voltages can saturate
the eﬃciency (Fig. 2), and that faster transportation is
expected.5)
We will measure the transportation eﬃciency throughthe QPIG with Cs ions and also with radioisotopes ofﬂine and online. In parallel, we will develop the gas
chromatographic apparatus connected to the gas cell.
References

1) A. Türler, V. Pershina, Chem. Rev. 113, 1237 (2013).
2) Y. Ito et al., Phys. Rev. Lett. 120, 152501 (2018).
3) M. Wada et al., RIKEN Accel. Prog. Rep. 52, 136 (2019).
4) F. Arai et al., Int. J. Mass Spectrom. 362, 56 (2014).
5) G. Bollen, Int. J. Mass Spectrom. 299, 131 (2011).

- 168 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

An attempt to modify the membrane degasser (MDG)
Y. Komori,∗1 K. Ooe,∗2 T. Yokokita,∗1 Y. Shigekawa,∗1 and H. Haba∗1
We have been developing a rapid solvent extraction
apparatus coupled to the GARIS gas-jet system foraqueous chemistry studies of element 106, Sg, and element 107, Bh.1,2) This apparatus consists of a continuous dissolution apparatus called a membrane degasser(MDG), a ﬂow solvent extractor (FSE), and liquid scintillation detectors. In the MDG, nuclear reaction products transported by the gas-jet method are continuously
mixed and dissolved with an aqueous solution. The gas
is removed through a hydrophobic membrane, and thesolution is injected to the FSE. In our previous studies,
we fabricated the MDG and studied the dissolution efﬁciencies of 90m Nb (T1/2 = 18.8 s), 90g Nb (14.6 h), and178aTa (2.36 h) produced in the nat Zr(d, x)90m, g Nb andnat
Hf(d, x)178a Ta reactions.1) We found that the dissolution eﬃciency of the short-lived 90m Nb isotope is as
low as approximately 50%, though those for the longlived 90g Nb and 178a Ta isotopes are greater than 80%.
We considered that the reason for the diﬀerence in dissolution eﬃciencies between the short-lived and longlived isotopes is as follows: (i) the gas-jet-transported
products are not mixed well with the aqueous solutionand (ii) the long-lived isotopes accumulate in the MDG.
In this work, we fabricated a miniaturized MDG to reduce the accumulation of the reaction products in the
MDG. A major modiﬁcation is the reduction of the inner volume of the MDG from 23 µL to 1.8 µL. We measured the dissolution eﬃciencies of 90m Nb, 90g Nb, and178a
Ta using the miniaturized MDG and compared theresults with those obtained with the conventional MDG.
We also studied the dissolution eﬃciencies of 144 Eu(T1/2 = 10.2 s), 143 Sm (68 s), and 143 Eu (2.59 min)using the conventional MDG. The 144 Eu with a half-lifeof 10 s is favorable because its dissolution eﬃciency isless inﬂuenced by the accumulation in the MDG thanthat of the long-lived isotopes.
90m, gNb and 178a Ta were produced in the same reactions as mentioned above. Two nat Zr foils with a thickness of 2.4 µm and four nat Hf foils with a thickness of
4.4 µm were irradiated with a 24 MeV deuteron beam
supplied by the RIKEN AVF cyclotron. The beam currents were 4.6 and 1.5 µA. The reaction products weretransported by the He/KCl gas-jet system to the miniaturized or conventional MDG in the chemistry laboratory. The ﬂow rate of the He carrier gas was 1.5 L/min.
Before entering the MDG, nuclear reaction products
were continuously mixed with 1 M HCl at a ﬂow rate of
1 mL/min inside a PTFE capillary of 0.75 mm inner diameter (i.d.) and 5 cm length. Eﬄuents from the MDG
were collected for 30 or 60 s with polypropylene tubes
and were subjected to γ-ray spectrometry with a Ge detector. The dissolution eﬃciencies were determined by∗1∗2

RIKEN Nishina Center
Osaka University Graduate School of Medicine

Table 1. Summary of the dissolution eﬃciencies obtainedwith the miniaturized and conventional MDGs.

Nuclide(Half-life)

Dissolution efficiency [%]Miniaturized

Conventional

MDG

MDG

Nb (18.81 s)

35 ± 236 ± 5

Ta (2.36 h)

53 ± 371 ± 7

Nb (14.6 h)

60 ± 2081 ± 10Eu (10.2 s)Ყ

43 ± 5143

Sm (68 s)

Ყ

74 ± 8Eu (2.59 min)

Ყ78 ± 12

90m

178a
90g

144

143

comparing the radioactivity in the eﬄuents with that
directly collected on a glass ﬁber ﬁlter. We also produced 144 Eu, 143 Sm, and 143 Eu through the nat Sm(d, x)
reaction. Six 144 SmF3 targets deposited on Ti foils, eachwith a thickness of 495 µg/cm2 were irradiated with a
24 MeV deuteron beam of 3.9 µA. The dissolution eﬃciencies of these nuclides were determined with the conventional MDG using almost the same procedures as for
90m, gNb and 78a Ta.
The dissolution eﬃciencies of 90m, g Nb and 178a Ta obtained with the miniaturized and conventional MDGs
are summarized in Table 1. Those of 144 Eu, 143 Sm, and143
Eu with the conventional MDG are also listed in Table 1. The dissolution eﬃciency of the short-lived 90m Nb
obtained with the miniaturized MDG is the same as thatobtained with the conventional MDG. The eﬃciencies ofthe long-lived 178a Ta and 90g Nb with the miniaturized
MDG are almost 20% lower than those with the conventional MDG. This might be the result of a decreasein the accumulation of the long-lived isotopes due tothe smaller inner volume in the miniaturized MDG. The
lower dissolution eﬃciency of the short-lived nuclides
such as 90m Nb and 144 Eu might be due to the insufﬁcient mixing of the gas-jet-transported products withthe aqueous solution. At this moment, we expect that adissolution eﬃciency of ∼40% is attainable for 265 Sga, b(T1/2 = 8.5 s, 14.4 s)3) and 266 Bh (T1/2 = 10.7 s) using this MDG.4) To increase the dissolution eﬃciency ofthese short-lived nuclides, more rapid and eﬃcient mixing of the gas with the aqueous solution is necessary. We
will improve the mixing unit of the MDG in the future.
References

1) Y. Komori et al., RIKEN Accel. Prog. Rep. 49, 29 (2016).
2) Y. Komori et al., RIKEN Accel. Prog. Rep. 50, 247 (2017).
3) H. Haba et al., Phys. Rev. C 85, 024611 (2012).
4) H. Haba et al., EPJ Web Conf. 131, 07006 (2016).

- 169 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Preparation of Gd targets for in-beam fission measurements as a step
towards the handling of 243 Am targets with ultra-thin backings
T. Tanaka,∗1,∗2 D. J. Hinde,∗1,∗2 H. Haba,∗2 M. Dasgupta,∗1,∗2 S. Battisson,∗1 A. C. Berriman,∗1 L. T. Bezzina,∗1
J. Buete,∗1 I. P. Carter,∗1 K. J. Cook,∗1 E. Graham,∗1 J. Heighway,∗1 T. D. Hume,∗1 D. Y. Jeung,∗1 Y. Komori,∗2
P. McGlynn,∗1 D. Mori,∗2 S. A. Parker-Steele,∗1 C. Sengupta,∗1 C. Simenel,∗1 E. C. Simpson,∗1 M. A. Stoyer,∗1,∗3
B. M. A. Swinton-Bland,∗1 Y. Wang,∗2 W. Wojtaczka,∗1 and T. Yokokita∗2

Table 1. Combinations of backing material, thickness andsubstrate.
Backing material
Ti
Cr
Al
∗1
∗2
∗3
a)

Thickness
200 nm
300 nm
300 nm
300 nm
740 nmSubstrate
Cu(3.6–4.7 µm)
KI-coated glass
Cu (3.8–4.4 µm)
self-supporting

160
58

140
120
Counts

The study of in-beam ﬁssion characteristics is of fundamental importance in understanding heavy-ion induced fusion reactions and the shell structure of ﬁssioning nuclei. Characteristic information is extracted fromthe measured velocities of the ﬁssion fragments. Since
the fragments lose kinetic energy when passing throughthe target and/or backing to reach the detectors, thinner targets and backings are favored for studies to decrease the systematic error. Additionally, safe handlingand survival of radioactive isotope (RI) targets in beam
are important factors. Since thinner targets and backings are fragile, the optimization of the backing material,
thickness and preparation procedures are key for studies
with RI targets.
In order to ﬁnd the optimum backing, a variety ofbackings with diﬀerent material, thickness, and substrate, were prepared, as indicated in Table 1. As thethin backings are too thin for electrodeposition of the
RI target, a substrate such as Cu is used to support thebacking during electrodeposition, and is subsequently removed. The Ti and Cr materials were evaporated using an evaporator at ANFF. a) The Cu substrates weredissolved by a solution made by combining 4 grams oftrichloroacetic acid (TCA), 20-mL 30% NH3 solution
and 20-mL deionized water, resulting in 40-mL of 9.3%
TCA solution, similar to that described in Refs. 1–3).
The success ratios for dissolving the Cu without breaking the backing materials were more than 80% for Ti
backing material and less than 50% for Cr backing material. Attempts to release the Ti-backings from KI-coatedglass by dissolving potassium iodide in water were notsuccessful because the backings were broken.
As a backing test, the backings, 200-nm Ti, 300-nm
Ti, and 300-nm Cr (once removed from the Cu sub-58

Ni+27Al

100
80
60
40
20
0

500 1000 1500 2000 2500 3000 3500 4000
Energy (ch)Fig. 1. Energy spectrum measured by a Si detector from thereaction of 58 Ni + nat Gd with Al backing.

strates), were irradiated by a 170 MeV 58 Ni12+ beam of
1 mm diameter, which was provided by the Heavy Ion
Accelerator Facility of the Australian National University. The 300-nm Ti backing survived beam irradiationof 1.5 enA for more than one hour.
Gd target material, instead of RI 243 Am, was successfully deposited on Ti-backing and Al-backing by electrodeposition utilizing the Hot-Lab of RIKEN Nishina
Center. The detailed procedures are similar to that described in Ref. 4). The thicknesses of 1.6-mm-diameter(5-mm-diameter) Gd targets were between 130 and 190(40 and 120) µg/cm2 .
The Gd targets on 300-nm-Ti/740-nm-Al backings
were tested with the same conditions as the backing test.
An energy spectrum measured by a Si detector, which
was mounted 15 cm downstream of the target at 18◦ withrespect to the beam axis, is indicated in Fig. 1. The clear
peaks indicate the elastic scattering from the reactionsof 58 Ni + nat Gd and 58 Ni + 27 Al, which demonstrate
the uniformity and quality of the target and backing.
The safety of all of procedures for handling the target, as well as the uniformity and quality of the target,
have been conﬁrmed. The 243 Am target will be preparedusing the same procedures as the Gd targets.
References

Department of Nuclear Physics, The Australian National University
RIKEN Nishina Center
Lawrence Livermore National Laboratory
Australian National Fabrication Facility, ANU node

Ni+natGd

1) G. T. J. Arnison, Nucl. Instrum. Methods Phys. Res. 53,
357 (1967).
2) B. Lommel et al., Nucl. Instrum. Methods Phys. Res. A
655, 44 (2011).
3) M. A. Stoyer et al., LLNL-TR-752862 (2018).
4) Y. Kudou et al., RIKEN Accel. Prog. Rep. 42, 265 (2009).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Preparation of [211 At]-labeled sodium astatide (NaAt) by reducing withascorbic acid for the treatment of thyroid cancer†
Y. Shirakami,∗1 K. Kaneda,∗1 A. Toyoshima,∗1,∗2 T. Watabe,∗3 K. Ooe,∗1,∗3 A. Shinohara,∗4 and J. Hatazawa∗4
Iodine-131 (131 I)-labeled sodium iodide, [131 I]-NaI, hasbeen used in clinics as the standard medication for patients with thyroid cancer. NaI can be transferred into
cancer cells via sodium-iodide symporters (NIS), resulting in cell death owing to β − particles emitted from the131
I atoms. The agent has some limitations: i) [131 I]-NaI
does not work in some patients, even though the agent
accumulates in tumor lesions, and ii) the patients treatedwith the drug require isolated hospitalization within aweek.
[211 At]-NaAt is expected to be a novel therapeutic
agent for patients with thyroid cancer as an alternative
to [131 I]-NaI because the linear energy transfer (LET) of
211
At is much higher than that of 131 I. Several papers
have proven the eﬃcacy of the drug in animals and humans.1,2) The drug, however, has not been well evaluatedin humans yet. One of the major problems of the agent isthe diﬃculty in the chemical identiﬁcation of NaAt due
to the lack of a stable isotope of astatine. The aim ofour study is to develop methods for the quality controlof the drug.
Bismuth-209 was irradiated with helium-4 (α) at
29 MeV, and 211 At was produced through the209
Bi(α, 2n)211 At reaction. The target was placed in aquartz tube and heated up to 850◦ C under a mixture ofhelium and oxygen gas ﬂow (30 mL/min and 10 mL/min,
respectively). Dry-distillated 211 At was collected in ateﬂon tube cooled in an ice-water bath. Through thetube, 100 µL of distillated water was passed, and an
aqueous solution of 211 At (bulk solution) was collected
in a micro PFA vial.
An aqueous solution of [211 At]-NaAt was prepared using the following procedures. An aliquot of the bulk solution was transferred to a glass vial containing an aqueous
solution of 7 w/v% sodium hydrogen carbonate. Subse-

Fig. 1. TLC profiles of the [211 At] bulk solution and [211 At]NaAt. Plate: Silica gel, Solvent: acetonitrile/water (2/1).
†

∗1
∗2
∗3
∗4

Condensed from the article in J. Nucl. Med. 60, 1301 (2019)
Institute for Radiation Sciences, Osaka University
RIKEN Nishina Center
Graduate School of Medicine, Tracer Kinetics and Nuclear
Medicine, Osaka University
Research Center for Nuclear Physics, Osaka University

Fig. 2. HPLC profiles of [211 At]-NaAt.
Column: reversed phase C-18 (Nakarai Tesque, Kyoto). Solvent:
20 mmoL/L tetrabutylammonium chloride/acetonitrile(7 : 3). Upper: UV trace, Bottom: RI trace.

quently, an aqueous solution of 3 w/v% ascorbic acid wasadded to the vial. The mixture solution was kept for 1 h
at room temperature. The radioactivity of the solution
was adjusted to 10 MBq/mL.
Representative TLC proﬁles of the [211 At] bulk solution and [211 At]-NaAt are shown in Fig. 1. The [211 At]
bulk solution was comprised of several radioactive spots
having irregular shapes (Fig. 1, upper). This result indicated that the bulk solution is a mixture of several chemical species of 211 At, including the higher oxidation statesof astatine (At+ and/or At3+ ) as well as astatide ion(At− ). The radioactive species were converged on a single component (relative to front (Rf) = 0.9, radiochemical purity (RCP) > 90%) after the addition of ascorbic
acid (Fig. 1, bottom). The component was also presented
as the major radioactive peak (retention time (Rt) =7.42 min, RCP > 90%) by high-performance liquid chromatography (HPLC) analysis, as shown in Fig. 2. The
component was estimated to be [211 At]-NaAt.
In thyroid cancer cells, the solution of [211 At]-NaAt
was accumulated in cells speciﬁcally via NIS. The solution also inhibited tumor growth in mice with thyroid
cancer.
These results suggest that ascorbic acid is eﬃcient forthe preparation of [211 At]-NaAt having high radiochemical purity. In conclusion, it is proved that [211 At]-NaAt
is a promising agent for the treatment of patients withthyroid cancer.
References

1) J. G. Hamilton et al., Exp. Biol. Med. 86, 366 (1954).
2) S. Carlin et al., J. Nucl. Med. 44, 1827 (2003).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Development of radioimmunotherapy with astatine-211-counjugatedantibodies
H. Takashima,∗1,∗2 Y. Koga,∗1,∗2 K. Onuki,∗3 S. Manabe,∗4,∗5 R. Tsumura,∗1 T. Anzai,∗1 N. Iwata,∗1
M. Yasunaga,∗1 Y. Wang,∗2 T. Yokokita,∗2 Y. Komori,∗2 D. Mori,∗2 H. Haba,∗2 H. Fujii,∗3 and Y. Matsumura∗1
Macromolecules and macroproteins hardly extravasatefrom blood vessels at a normal organ site due to theirlarge molecular weight. By contrast, since the permeability of blood vessels at tumor sites is higher thanthat at normal organs, macromolecules and macroproteins can extravasate from tumor vessels. Moreover,due to the poor lymphatic drainage system at tumor
sites, macromolecules and macroproteins are retained
for a prolonged time after extravasation. As a result,macromolecules and macroproteines selectively and efﬁciently accumulate in tumors. This phenomenon isthe enhanced permeability and retention (EPR) eﬀect,1)
which is the rationale of drug delivery systems for cancer treatment. Antibodies such as immunoglobulin G(IgG), the molecular weight of which is approximately
150 kDa, accumulate in tumors via the EPR eﬀect. In
addition to the EPR eﬀect, antigen-antibody interaction
with target molecules expressed in tumors enhances thetumor accumulation of antibodies.2)
We successfully produced several types of monoclonal
antibodies (mAbs) that recognize target molecules
highly or speciﬁcally expressed in tumors, and appliedmAbs to drug carriers. The antibody-drug conjugate(ADC) is composed of an mAb that recognizes target molecules in tumors and low-molecular weight anticancer agents, and it is an example of armed antibodies. Previously, using our mAbs, we prepared ADCs anddemonstrated that they showed potent antitumor eﬀects
in cancer xenograft models.3–5)
Alpha particles are characterized by higher liner energy transfer (LET) and shorter range in tissue thanother types of radiation, resulting in eﬃcient deoxyribonucleic acid (DNA) double-strand breaks in accumulated cells with minor eﬀects on adjacent cells. Accordingly, since the successful delivery of alpha emitters totumor sites is expected to yield eﬃcient antitumor effects with mild toxicity, we focus on the developmentof radioimmunotherapy (RIT) with an alpha-emitterconjugated antibody.
In this study, we labeled antibodies with astatine211, one of the most promising alpha emitters for cancer
treatment, and evaluated the binding activities and invitro cytocidal eﬀects of the radioactive antibodies.
We synthesized astatine-211 in the 209 Bi(α, 2n)211 At
reaction using the RIKEN Azimuthally Varying Field
∗1
∗2
∗3
∗4
∗5

Developmental Therapeutics, Exploratory Oncology Research& Clinical Trial Center (EPOC), National Cancer Center
RIKEN Nishina Center
Division of Functional Imaging, EPOC, National Cancer Center
Synthetic Cellular Chemistry Laboratory, RIKEN
Research Center for Pharmaceutical Development, Tohoku
University

Fig. 1. Flowchart to prepare astatine-211-conjugated antibodies.

(AVF) cyclotron.
Figure 1 shows a ﬂowchart to prepare astatine211-conjugated antibodies. First, we reduced the interchain disulﬁde bonds of mAbs4,5) and attached atrimethylstannyl benzoate linker to an mAb with reactive sulfhydryl groups via a thioether bond between
the sulfhydryl and maleimide groups. Then, we labeled liker-antibody complexes with astatine-211 via a
halogen-exchange reaction. Subsequently, the astatine211-conjugated antibodies were puriﬁed away from unconjugated astatine-211 using a PD-10 desalting column(GE Healthcare Life Sciences, Chicago, IL, USA). To
increase the labeling eﬃciency, we optimized the procedure to purify astatine-211 from bismuth and calculated
the labeling rate by dividing the radioactivities of immunoconjugates by those of astatine-211 that was initially applied to the reaction solution (100 MBq); thelabeling rate was approximately 60%. We successfully
prepared astatine-211-conjugated antibodies using bothmAbs newly developed by us and trastuzumab, a clinically available mAb for patients with breast or gastriccancer.
We evaluated the aﬃnity of astatine-211-conjugatedantibodies by ﬂow cytometry. The radioactive antibodies bound to cancer cells depending on the expression
level of target molecules on the cell membrane, and thespeciﬁc aﬃnity of immunoconjugates was comparable
to the corresponding mAbs. As a result, astatine-211conjugated antibodies exerted in vitro cytocidal eﬀects
on cancer cells depending on the expression of target
molecules on the cell membrane.
In conclusion, we synthesized astatine-211 using the
RIKEN AVF cyclotron and succeeded in constructing
astatine-211-conjugated antibodies. The present data
warrant further basic studies for future clinical development.
References

1) Y. Matsumura et al., Cancer Res. 46, 6387 (1986).
2) H. Takashima et al., Sci. Rep. 7, 12341 (2017).
3) Y. Koga et al., Int. J. Cancer. 137, 1457 (2015).
4) R. Tsumura et al., J. Control. Release. 284, 49 (2018).
5) H. Fuchigami et al., Sci. Rep. 8, 14211 (2018).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Anti-cancer eﬀect of 211 At-labeled antibody on xenografted mice withintravenous injection
Y. Kanayama,∗1 K. Sakamoto,∗2 R. Zochi,∗1 Y. Wang,∗3 T. Yokokita,∗3 Y. Komori,∗3 D. Mori,∗3 H. Haba,∗3 andY. Watanabe∗1
Uptake rates [%ID/g]

35
30

3h

25

24h

48h

26.10
21.47

20
15
10
5
0

UL

BL

HE

LU

SP

PA

LI

KI

ST

IN

FM

TH A431 C6

GB

Fig. 2. Biodistribution in xenografted mice (n = 4). A431,
HER2 positive; C6, HER2 negative.
1200

Tumor size [mm^3]

Astatine-211 is a promising α emitter for targeted
α therapy because of its simple decay scheme, which
can avoid undesirable radiation from daughter nuclides.
In a previous study, we investigated the radiolabeling method of 211 At on monoclonal antibodies using astannyl compound (m-MeATE). The synthesis of 211 Atlabeled IgG was successful, but we observed the detachment of 211 At 24 h after intravenous (IV) injection.
To overcome the deastatination, the use of decaborane,
a boron cluster compound, is a possible solution because its binding to astatine is more stable in vivo.1)
However, as we have previously reported,2) the 211 Atdecaborate moiety may increase hydrophobicity, which
probably causes its poor bioavailability, resulting in the
low tumor uptake by IV injection. In the present study,
we introduced a PEG linker between decaborate and IgG
to decrease the hydrophobicity. By using this conjugate,
we investigated the anti-cancer eﬀect of 211 At-labeledtrastuzumab on HER2-positive cancer xenografted micewith IV injection.
The 211 At-decaborate (B10)-PEG5-trastuzumab was
obtained through the 3-step synthesis (Fig. 1). We used
46 MBq of 211 At produced in the 209 Bi(α, 2n)211 At reaction at the RIKEN AVF cyclotron for labeling 40 µg of
the antibody-linker conjugate, and the mixture after thereaction was applied to ﬁltration with G50 DNA-grade
gel to remove free 211 At and replace it with physiologicalsaline. The radioactivity yield was 65% (30.2 MBq was
retained on the antibody), with the protein recovery rate
being 64%. The speciﬁc radioactivity was 1.08 MBq/µg.
We ﬁrst investigated the bio-distribution of the 211 Atlabeled trastuzumab in xenografted mice 3, 24, and48 h after IV injection. Figure 2 shows that 211 Attrastuzumab was in the blood at signiﬁcant levels(around 15%ID/g) for 48 h and progressively accumulated in the target A431 tumor region (up to approximately 20%ID/g) during the same period. On the other
hand, the control C6 tumor region did not show a signiﬁcant accumulation from 24 to 48 h. This result wasconsistent with the typical outcome of a PET imaging

1.8 MBq At-Tra (n=4)

1000

1.0 MBq At-Tra (n=4)
1.0 MBq Free At (n=5)

800
600
400
200
0

0

6

12

18

Day

24

30

36

Fig. 3. Average tumor size of the mice after IV injection of211
At-B10-PEG5-trastuzumab.

study using 64 Cu-labeled trastuzumab.
Subsequently, we proceeded to examine the anticancer eﬀect of 211 At-trastuzumab via IV injection. Twogroups of mice were administered 1.8 or 1.0 MBq of211
At-trastuzumab (1.7 µg), while the control group was
administered 1.0 MBq of free 211 At. The changes in the
body weight and tumor size, as well as the survival rate
were observed up to 36 days after the IV injection (Day0) (the tumor size is shown in Fig. 3).
A larger dose (1.8 MBq) of 211 At-Trastuzumab caused
a severe decrease in the body weight within a week, implying a serious side eﬀect of the injection, and led tothe euthanization of a mouse. The 211 At-trastuzumabin either dose successfully suppressed the growth of thetumor in size with only one shot of the IV injection, andno mice died because of the tumor. No adverse eﬀects
were observed in the 1.0 MBq At-Tra group. In con2. Cu-free click chemistry 1. Amine coupling
trast, the tumor grew much more rapidly in the control
211(SPAAC)
3. Covalent aaching of At
group, with no mice alive until Day 36. Thus, we suc211At
cessfully demonstrated the favorable anti-tumor eﬀect of
NH2
211
At-B10-labeled trastuzumab conjugated with a PEG
DBCO-PEG4-decaborate NHS-PEG1-azide Trastuzumab linker, which was probably supported by the improved
biodistribution.
211
Fig. 1. Synthesis of

∗1
∗2
∗3

At-B10-PEG5-trastuzumab.

Laboratory for Pathophysiological and Health Science,
RIKEN
Laboratory for Nonnatural Amino Acid Technology, RIKEN
RIKEN Nishina Center

References

1) F. Guerard et al., Cancer Biother. Radiopharm. 28, 1(2013).
2) K. Fujiki et al., Chem. Sci. 10, 1936 (2019).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Dispersion rates of astatine-211 from aqueous solutions andchloroform†
A. Toyoshima,∗1,∗2,∗3 K. Nagata,∗2,∗3 K. Ooe,∗1,∗3,∗4 Z. Zhang,∗2,∗3 T. Ikeda,∗3 S. Ichimura,∗3 H. Obata,∗3
T. Yoshimura,∗2,∗3 and A. Shinohara∗2,∗3
Airborne concentrations of radioactive materials are
crucial for the evaluation of human exposure and radiation protection protocols. An important factor inﬂuencing airborne radioactivity concentration is the dispersal
rate from a radioactive solid or liquid sample, which depends on the chemical forms of the radioactive materials.
Therefore, to evaluate the airborne concentration, it isindispensable to experimentally determine the dispersal
rates under various conditions. Recently, targeted alphatherapy using a short-lived radioisotope emitting α particles was developed.1) 211 At with a half-life of 7.2 h is apromising α-emitter for the therapy.2) However, becauseof the lack of long-lived At isotopes, its dispersion has
been rarely studied.3) For realistic and eﬀective clinicaluse of 211 At, the evaluation of its airborne concentration is necessary. Herein, we investigated the dispersal
rates of 211 At in aqueous acidic, neutral, and alkaline
solutions and in chloroform.
211
At was produced in the 209 Bi(α, 2n)211 At reaction
using the AVF cyclotron at the Research Center of Nuclear Physics, Osaka University. 211 At was also supplied
from RIKEN through the Supply Platform of Short-lived
Radioisotopes. 211 At was then separated from the irradiated Bi target by dry distillation. The experimental
setup to measure the dispersal rate of 211 At is shown in
Fig. 1. Details of the setup can be found in the full article. A plastic cylinder was connected to a ﬁlter holder inwhich a glass-ﬁber ﬁlter paper, charcoal-impregnated ﬁlter paper, and two charcoal cartridges were placed. The
inside of the cylinder was covered with a thin polyethylene terephthalate sheet to catch dispersed 211 At on its
surface. An air pump for ventilation was connected tothe top of the holder. To a 100 mL beaker, 0.010 mLof the 211 At stock solution was added to 20 mL of theaqueous solutions and chloroform. To a 1.5 mL microtube, 0.002 mL of the 211 At solution was pipetted into
0.50 mL of the aqueous solutions. The radioactivity of211
At used in a single run was 0.4–2 MBq at the startof the experiment. The interior of the system was ventilated at an air ﬂow rate of 30 L/min. The solution
was stirred with a magnetic stirrer during ventilationfor 60 min. Subsequently, the characteristic 79 keV Xray of Po attributed to the electron capture (EC) decayof 211 At in/on the sample solution, vessel, ﬁlter papers,
cartridges, etc. was measured using a Ge detector.
Under all the studied conditions, the recovered yieldsof 211 At were 100% within the error. This indicatesthat dispersed 211 At was completely collected using the
setup. For the 100 mL beaker data, the dispersal rate of211
At depended on the solution acidity, where 13% and
16% of 211 At dispersed moderately in the acidic and basic solutions, respectively, and 30% dispersed in the neutral buﬀer. In contrast, for the microtube, the dispersal
rates of 211 At were much smaller (2–4%) than those fromthe beaker and were largely unchanged among the studied conditions. These results clearly show that 211 At dispersion was suppressed in the microtube because of themuch smaller liquid surface area and was not strongly
inﬂuenced by solution conditions. Upon the additionof ascorbic acid (AA) to the neutral buﬀer, the dispersal rate of 211 At was remarkably suppressed because of
the reduction of the originally present At species to themonovalent ionic At− .4) In our previous clinical study
with Na211 At,5) AA was required to be admixed at 1.2
weight/volume% to 211 At-stocked distilled water as astabilizer in vivo. Thus, for the actual use of Na211 At,
the dispersal rate of 211 At can be extremely low. In
chloroform as well, a very low dispersal rate of 211 At
was observed.
In conclusion, the dispersal rates of 211 At were foundto vary depending on the solution conditions, with the
maximum dispersion observed at pH 7. In the neutral
solution containing AA, the dispersion rate of 211 At wasquite low, suggesting that the dispersion of 211 At shouldbe negligible in future clinical studies with Na211 At.

†

References

∗1
∗2
∗3
∗4

Condensed from the article in Radiat. Saf. Manage. 18, 16(2019)RIKEN Nishina Center
Institute for Radiation Sciences, Osaka University
Graduate School of Science, Osaka University
Osaka University Graduate School of Medicine

Fig. 1. Experimental setup for the measurement of dispersal
rates of 211 At.

1) M. R. McDevitt et al., Eur. J. Nucl. Med. 25, 1341 (1998).
2) F. Guérard et al., Cancer Biother. Radiopharm. 28, 1 (2013).
3) U. Lindencrona et al., Appl. Radiat. Isotopes 62, 395 (2005).
4) J. Champion et al., J. Phys. Chem. 117, 1983 (2013).
5) T. Watabe et al., J. Nucl. Med. 60, 355 (2019).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Usability of 67 Cu as a therapeutic radioisotope for peptide receptor
radionuclide therapy
Y. Fujisawa,∗1 H. Haba,∗2 Y. Magata,∗3 and Y. Iida∗1
Copper-67 is an attractive radionuclide for nuclear
medicine therapy, which has an emitted β-particle energy suitable for applying to small tumors and a physical half-life of 61.8 hours long enough to damage them.
Recently, radiolabeled somatostatin (SST) analogues
targeting SST receptor-2 are useful for diagnosis andtherapy of neuroendocrine tumors (NETs). And peptide receptor radionuclide therapy (PPRT) has become one of the most promising treatments for patientswith well to moderately diﬀerentiated unresectable ormetastatic NETs. High energy β-particle-emitting 90 Y
(2.28 MeV) becomes available for this therapy andshows high eﬃcacy, but its application is limited byadverse eﬀects.1) 67 Cu emits middle energy β-particles(0.39–0.58 MeV), and its maximal tolerated activity
dose is much higher than 90 Y. So, 67 Cu may have an
advantage in treating relatively small tumor masses.2)
In this study, we prepared a novel SST derivative,
ToDBTTATE, labeled with 67 Cu (Fig. 1), and evaluated its potential for cancer therapy in mice bearing
AR42J rat pancreatic tumor cells. ToDBTTATE has
a ligand, diacetyl-bis (N 4 -methylthiosemicarbazone)(ATSM), which releases a copper in hypoxic condition
such as tumor in its structure and the copper will remain at the site.3)
The ligand which was synthesized from 4-Methyl-3thiosemicarbazide according to the procedure reported
by Paterson et al.4) was bound to TATE, a most frequently used SST analog in clinical practice and 67 CuToDBTTATE was obtained from reaction with 67 Cu
with microwave synthesis system. Tumor-bearing mice
were prepared by implantation of AR42J tumor cells(5 × 106 cells) in 0.1 mL PBS into the ﬂanks of nude
mice (BALB/c-nu/nu, male). Biodistribution experiments were performed by intravenously administering
OH

N
N
N
H

N 67

Cu

H
N

N

O
O

O

O

N
H

S

S

O
HO
HO

H
N
O

O

H
N

N
H

O
HN

S
S

H
N
O

O
N
H
HO

O

NH

O
NH
NH2

∗2
∗3

*†

,

Faculty of Pharmaceutical Sciences, Suzuka University of
Medical Science
RIKEN Nishina Center
Department of Molecular Imaging, Hamamatsu University
School of Medicine- 175 -

*†

,

,

*†

Fig. 2. Therapeutic studies of 67 Cu-ToDBTTATE. *, † Differences between the group of 67 Cu-ToDBTTATE andnon-treatment (*)/ligand only (†) were determined at
p < 0.05 by using Graph Pad PRISM ver. 6.05 (ANOVA
followed by Tukey’s test).

Cu-ToDBTTATE. The mice were killed at 1, 24 and48 h after administration, and tissue of interest were
excised and weighed after which their radioactivity
was measured. For therapeutic studies, AR42J tumors
were grown in BALB/c mice in the same way. Mice
were intravenously administered with 17.9–25.2 MBq
of 67 Cu-ToDBTTATE. Untreated mice were used as acontrol. Mice were weighed and tumor diameters wererecorded regularly. The diameters of tumors were measured with a caliper, and tumor volumes were determined using the following formula: (longer diameter)× (shorter diameter)2 /2.
67
Cu-ToDBTTATE showed high accumulation in
the tumor, 2.62 ± 0.46, 1.75 ± 1.20 and 1.80 ± 0.44%
ID/g at 1, 24 and 48 h after administration, respectively. Substantial tumor size reduction was observedin all mice treated with 67 Cu-ToDBTTATE (Fig. 2).
As this result, 67 Cu-ToDBTTATE is a promising agent
for the treatment of NETs and 67 Cu is expected to besuitable for treatment of relatively small tumor. The
use of 67 Cu for cancer therapy has also potential foreﬃcient tailor-made therapy.
67

References

Fig. 1. Chemical structure of 67 Cu-ToDBTTATE.
∗1

non treatment, n = 4
ToDBTTATE (ligand only), n = 6
67Cu-ToDBTTATE (17.9 – 25.2 MBq), n = 61) G. A. Wiseman et al., Eur. J. Nucl. Med. 27, 766 (2000).
2) E. B. van Dieren et al., Int. J. Radiat. Oncol. Biol. Phys.
36, 197 (1996).
3) F. Dehdashti et al., Eur. J. Nucl. Med. Mo. Imaging
307, 844 (2003).
4) B. M. Paterson et al., Inorg. Chem. 49, 1884 (2010).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Quality evaluation of RIKEN 67 Cu for labeling peptide compound
S. Oshikiri,∗1 H. Kato,∗1 D. Mori,∗1 A. Hino,∗2 and H. Haba∗1
Copper-67 (67 Cu) with a half-life of 2.58 days is oneof the promising RIs for both diagnosis and therapy innuclear medicine. We have been developing a technology for producing 67 Cu via the 70 Zn(d, αn)67 Cu reaction using the RIKEN AVF cyclotron and distributing
puriﬁed 67 Cu products (RIKEN 67 Cu) to the generalpublic through the Japan Radioisotope Association.1)
In this work, we investigated the availability of RIKEN
67
Cu for radiolabeling a peptide compound.
DOTA-Substance P (DOTA-SP) is DOTA-peptidethat has been studied as a candidate radiopharmaceutical for glioblastoma.2,3) In the present study, we selected DOTA-SP as a model compound.
The labeling method of 67 Cu-DOTA-SP is as follows.
Step 1: RIKEN 67 Cu chloride (2.6 MBq) was dissolved
in 0.05 M hydrochloric acid to prepare a 67 Custock solution (80 MBq/mL). The radioactivity of 67 Cu was determined using a germanium
semiconductor detector.
Step 2: DOTA-SP was dissolved in 0.75 M sodium acetate buﬀer at pH5.0 to prepare 14 × 10−5 ,4.6 × 10−5 , and 0.92 × 10−5 M DOTA-SP solutions.
Step 3: 2.0 µL of the 67 Cu-stock solution was added to
1.0 µL of each DOTA-SP solution. The mixture of the 67 Cu-stock solution and DOTA-SP
solutions of 14 × 10−5 , 4.6 × 10−5 , and 0.92 ×
10−5 M resulted in 1.2, 3.5, and 17 MBq/nmol
solutions, respectively.
Step 4: The mixture in Step 3 was heated at 97◦ C for
10 min and kept at a room temperature for5 min.
Step 5: Labeling yields of 67 Cu-DOTA-SP were determined using the thin-layer chromatography (TLC) method with a C18 reversed-phase
TLC plate (NAGEL PR-18W/UV254) andeluted with a mixture of acetonitrile, 0.5 M
ammonium acetate, methanol, and tetrahydrofuran in a volume ratio of 4:3:2:1.
Figure 1 shows the labeling yield (%) as a functionof the speciﬁc radioactivity of 67 Cu-DOTA-SP. RIKEN
67
Cu was used to label DOTA-SP with the highest
yield at 1.2 MBq/nmol. The yield decreased with anincrease of the speciﬁc radioactivity.
In previous research using another DOTA-peptide,
DOTA-TATE, the labeling yield with 64 Cu was reported to be 97% at a speciﬁc radioactivity of
7 MBq/nmol.4) 64 Cu is a radionuclide with a half-life of
12.7 h. We can convert thereported speciﬁc radioac∗1∗2

RIKEN Nishina Center
RI Research Department, FUJIFILM Toyama ChemicalCo., Ltd.

- 176 -

Fig. 1. Relation between specific activity (MBq/nmol) andlabeling yield (%) of 67 Cu-DOTA-SP.

tivity of 7 MBq/nmol for 64 Cu into 1.4 MBq/nmolfor 67 Cu. This is comparable with our result at
1.2 MBq/nmol in DOTA-SP and might be applicableto other compounds with such a speciﬁc radioactivityof RIKEN 67 Cu. This speciﬁc radioactivity was considered to be suﬃcient for use in studies such as invitro/in vivo studies to examine candidate radiopharmaceuticals.
In this study, we evaluated the quality of RIKEN
67
Cu through DOTA-SP labeling and revealed thatRIKEN 67 Cu has a high and suﬃcient quality to label compounds such as DOTA-peptides for studies onradiopharmaceuticals.
References

1) S. Yano et al., RIKEN Accel. Prog. Rep. 49, 22 (2016).
2) A. Majkowska-Pilip et al., Molecules 23, 2542 (2018).
3) L. Królicki et al., Eur. J. Nucl. Med. Mol. Imaging 46,
614 (2019).
4) S. N. Rylova et al., PLoS One 13, e0195802 (2018).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Simultaneous imaging of Na+ /K+ by semiconductor Compton camera
GREI†
S. Motomura,∗1 I. Kii,∗1,∗2 H. Haba,∗3 H. Yakushiji,∗1 Y. Watanabe,∗1 and S. Enomoto∗4
Various metal elements exist in a living body andare used as essential factors for maintaining life. For
example, sodium (Na) and potassium (K) are homologous alkali metals that are clearly distinguished by somebiomolecules and used for forming a membrane potential
required for nerve activity. Since various metal elements
in a living body are controlled by specific biomolecules,
it is expected that the behavior of these metal elementschanges in diseased tissues.
We are exploring the possibility of a new concept of
diagnostic imaging that diagnoses the function of a living organism by non-invasive visualization of the dynamics of associated metal elements in vivo. In particular,a nuclear medicine imaging technique, which takes theimages of the radioisotopes (RIs) of the metal elements
to be traced, enables the visualization of the dynamics of a deep part of a living body by administering asmall amount of RIs. As for Na and K, 24 Na, 42 K, and43
K have suitable half-lives for administration to a living body: 15, 12, and 22 h, respectively. However, sincethese are not positron-emitting nuclides, they cannot be
imaged by PET, and the gamma-ray energies of the nuclides are too high for use in SPECT.
Therefore, we are studying the imaging of 24 Na, 42 K,
and 43 K using a semiconductor Compton camera called
GREI1,2) to visualize the dynamics of Na+ and K+ in
a living body. We have already obtained various resultsin the simultaneous imaging of multiple nuclides that
emit gamma rays from about 200 KeV to 2 MeV by using GREI equipped with germanium semiconductor detectors as gamma-ray sensors. In addition, it is possible to create three-dimensional images simply by taking
an image from one direction with a single imaging headFig. 1. RI solutions of 24 Na and 42, 43 K collected in micro
tubes. The gap between the tips of the micro tubes was 1 cm.
†
∗1
∗2
∗3
∗4

Presented at The 14th Annual meeting of Japanese society formolecular imaging, May 23–24, (2019)
RIKEN Center for Biosystems Dynamics ResearchCompass to Healthy Life Research Complex Program, RIKEN
RIKEN Nishina Center for Accelerator-Based Science
RIKEN Center for Life Science Technologies

Fig. 2. Gamma-ray energy spectrum measured by GREI.

Fig. 3. Gamma-ray images of 24 Na and 42, 43 K simultaneously measured by GREI.

without arranging a large number of sensors around theimaging target or rotating the imaging head.
Since FY2018, the use of these nuclides has been madepossible at the Molecular Imaging Facility at RIKEN
Kobe campus, and a series of protocols for manufacturing and preparing 24 Na, 42 K, and 43 K in-house andconducting GREI imaging experiments have been established. To demonstrate the feasibility of simultaneous
imaging of these nuclides by GREI, we performed a test
imaging experiment by using RI solutions.
RI solutions of 24 Na and 42, 43 K were collected at thetips of two micro tubes separately (Fig. 1). 42 K and 43 K
were not separated, because they are chemically identical. The radio-activities of 24 Na, 42 K, and 43 K were
2.1 MBq, 910 kBq, and 76 kBq, respectively. The tubes
were placed under the GREI imaging head 3.5 cm awayfrom the front detector. The GREI imaging was performed for 1 h.
Figure 2 shows the gamma-ray spectrum obtained in
the GREI imaging experiment. We were able to clearly
identify the gamma-ray peaks of each nuclide. By settingenergy windows on the peaks of each nuclide, we performed three-dimensional image reconstruction on therecorded data. As a result, we succeeded in taking theimages of 24 Na and 42, 43 K simultaneously.
References

1) S. Motomura et al., J. Anal. At. Spectrom. 28, 934 (2013).
2) T. Ida et al., Jpn. J. Appl. Phys. 58, 016002 (2019).

- 177 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Research progress on double-photon-emission coincidence imaging withcascade gamma-ray-emitting nuclide
M. Uenomachi,∗1 Z. Zhong,∗1 K. Shimazoe,∗1 H. Takahashi,∗1 D. Mori,∗2 T. Yokokita,∗2 Y. Komori,∗2 and
H. Haba∗2
Positron emission tomography (PET) and singlephoton-emission computed tomography (SPECT) are
important nuclear medicine modalities that have been
widely used for clinical diagnosis. PET detects the coincidence of annihilation gamma-rays from a positronemitting nuclide. SPECT uses a collimator to restrict theincident direction of gamma-rays. Therefore, nuclides for
PET imaging are limited to positron-emitting nuclides
and there is a theoretical spatial resolution limit derived
from the positron range. The sensitivity of SPECT is relatively low because of its use of a collimator, and it is difﬁcult to image multiple nuclides simultaneously. To realize highly sensitive multi-nuclide imaging, we proposed adouble-photon -emission coincidence imaging method.1)
For SPECT imaging, single-photon-emitting nuclides
are preferable. Among them, there are nuclides that
emit two photons in cascade decay. For example, 111 In,
which is widely used in SPECT imaging, emits two
gamma-rays at 171 keV and 245 keV. Using two gammarays, the position of nuclides can be determined withhigher sensitivity. One of the methods using two gammarays is double-photon-emission computed tomography(DPECT).1,2) This method can drastically increase thesignal-to-noise (SN) ratio of Compton imaging3) by coincidence detection for cascade gamma-rays with multiple
Compton cameras, which is based on Compton scattering kinetics. Conventional Compton imaging can obtain
only the angle information of incident gamma-rays, anddrawing many Compton cones results in a low SN ratio.
However, DPECT can limit the nuclide position from a
Compton cone to an overlap of two Compton cones. We
previously demonstrated DPECT using 134 Cs and 60 Co
for application to fuel debris imaging2) with GAGGSiPM Compton cameras.4) In the present research, wedeveloped small GAGG-SiPM Compton cameras for application to nuclear medicine and demonstrated doublephoton-emission coincidence methods using 43 K, which
is one of the promising double-photon-emitting nuclides
because of its short decay time and suitable gamma-ray

Fig. 2. Single-photon Compton imaging at (a) 373 keV and(b) 617 keV. (c) Time diﬀerence of DPECT (camera1camera2).

energies.
43
K was produced in the 43 Ca(d, 2p)43 K reaction at
the RIKEN AVF cyclotron. After chemical separation,
2 (6) MBq of 43 K in 6 (18) µL H2 O was placed in avial as a gamma-ray source. Figure 1 shows the experimental setup of DPECT for 43 K. 43 K mainly emitscascade gamma-rays at 617 keV and 373 keV. A Compton camera consists of a scatter layer and an absorberlayer. Each layer consists of an 8 × 8 GAGG array coupled to an 8 × 8 SiPM array. The thicknesses of the
GAGG arrays is 4 mm and 9 mm for scatterers and absorbers, respectively. The pixel size of the GAGG arrays
is 2.5 mm × 2.5 mm, and each crystal is separated by
BaSO4 reﬂectors. The signal from SiPM is processed by
the dynamic time over threshold (dToT) method5) to extract the energy. The distance from the 43 K source toa scatterer was 30 mm, and two Compton cameras wereplaced in opposite directions.
Figures 2(a) and 2(b) show images reconstructed
through back projection. Figure 2(a) shows a singlephoton Compton image at 373 keV and (b) shows animage at 617 keV. We succeeded in obtaining images ofsingle-photon Compton imaging with our small Compton
cameras. Figure 2(c) shows a histogram of time diﬀerence of double Compton coincidence events at 373 keV
and 617 keV. However, the number of coincidence events
that can be used for DPECT with Compton scattering
energy windows was only 12. After this experiment, we
increased the number of Compton cameras to detect double Compton coincident events eﬃciently and repeatedthe experiment with eight modules. The result is underanalysis.
References

Fig. 1. Experimental setup of DPECT for 43 K.
∗1∗2

Department of Engineering, The University of Tokyo
RIKEN Nishina Center

1) Y. Yoshihara et al., Nucl. Instrum. Methods Phys. Res. A
873, 51 (2017).
2) M. Uenomachi et al., Nucl. Instrum. Methods Phys. Res.
A 954, 161682 (2020).
3) R. W. Todd et al., Nature 251, 132 (1974).
4) J. Jiang et al., J. Nucl. Sci. Technol. 53, 1067 (2015).
5) K. Shimazoe et al., IEEE Trans. Nucl. Sci. 59, 3213 (2012).
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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Production of Np-236 in the 232 Th + 7 Li reaction for standard materialin accelerator mass spectrometry
Y. Hayakawa,∗1,∗2 A. Yokoyama,∗1,∗3 A. Sakaguchi,∗1,∗4 K. Teranishi,∗1,∗2 R. Morita,∗1,∗2 N. Matsumura,∗1,∗3
A. Nakajima,∗1,∗4 D. Mori,∗1 Y. Komori,∗1 T. Yokokita,∗1 Y. Wang,∗1 and H. Haba∗1
Neptunium-236 can be a useful tracer in the determination of 237 Np, an isotope of minor-actinide Np, which
exists in tiny quantities in the environment owing to
its release from nuclear facilities. Such determination
is of practical use in various earth science ﬁelds such as
surface material circulation and environmental pollution
assessment.1) The measurement of 237 Np is expected tobe quantiﬁed by accelerator mass spectrometry (AMS),
although an internal standard method for Np needs anappropriate spike. Tracers for several elements are available now, but the spike for neptunium has not been developed yet. We aim to devise an eﬃcient method forthe production of 236 Np in the ground state of half-life
1.54 × 105 y as a candidate for the spike nuclide.
In this study, 236 Np tracer production was implemented in the reaction of 232 Th + 7 Li to measure 237 Np.
In the beginning of the project, the excitation functionsof Np isotopes and by-products were measured using target stacks of Th metal foils. We irradiated the targets
with 42 MeV 7 Li ions from the RIKEN AVF cyclotron
while integrating the beam current with a Faraday cup
in the irradiation course. Chemical procedures were performed to isolate Np atoms from the target. The target material was dissolved in a mixed acidic solution of
0.027 M HF and 3 M HNO3 , and the sample was driedby heating. Then, the residue was adjusted to 4 mL of
3 M HNO3 solution, reduced with ascorbic acid and Fe

Fig. 1. Excitation functions of the production of Np-236m
and Np-236g isomers.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Graduate School of Natural Science and Technology,
Kanazawa University
Institute and College of Science and Engineering, Kanazawa
University
Center for Research in Isotopes and Environmental Dynamics,
University of Tsukuba

Fig. 2. Isomeric ratios of 236 Np and angular momenta transferred into targets.

ions and introduced into a TEVA resin column; subsequently, it was treated with 3 M HNO3 and 10 M HClfor puriﬁcation and ﬁnally with 0.1 M HCl for the elution of Np. To remove Pa, another process with a TK
400 column was performed. To determine the yields of
Np isotopes and by-products, γ-ray spectrometry was
conducted for the eﬄuents with a Ge detector. For the
Np-236g measurement, samples for AMS and ICP-MS
were prepared through puriﬁcation with UTEVA resin
after waiting for Np-236m to decay out, and they werebrought to the VERA facility in the University of Vienna, with which this project is in collaboration.
Figure 1 shows the excitation functions of the production of Np-236m and Np-236g. The yield in the groundstate (6−) was found to be larger than that in the excited state (1+) in the studied energy range, although
the former data are preliminarily taken.
Isomeric yields of the product are thought to be correlated with angular momentum in the composite system
if their spins substantially diﬀer from each other. The
maximum orbital angular momenta transferred to the
nuclear system were estimated using the ALICE code2)
and compared to the isomeric ratios of 236 Np in Fig. 2.
The ﬁgure shows the correlation of observation to angular momenta. The analysis of the result is in progress,
and additional experiments including mass spectrometry are in planning to conﬁrm the precision and reproducibility of the data.
References

1) W. Rund, G. S. Goﬀ, in Radionuclides in the Environment, edited by D. A. Atwood (Wiley, 2013).
2) M. Blann, “CODE ALICE/85/300,” UCID-20169 (September 1984).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Excitation function measurement of the Tl(d, α)203 Hg reaction for
carrier-free 203 Hg tracer production
Y. Takahashi,∗1 S. Goto,∗1 D. Mori,∗2 T. Yokokita,∗2 Y. Komori,∗2 Y. Wang,∗2 and H. Haba∗2

Table 1. Measured nuclides and their nuclear data.6–9)
Nuclide
204m
Pb
203
Pb
202m
Pb
201g
Pb
202
Tl
201
Tl
203
Hg
∗1
∗2

Half-life
66.93 min
51.92 h3.54 h
9.33 h12.31 d3.0421 d
46.594 dEγ /keV899.15279.1952
422.12311.15439.51167.43279.1952

Iγ /%99.14480.9
84.108
76.90
91.5
10.00
81.56

104
203

103
Count rate / cps

The inﬂuence of relativistic eﬀects on orbital electrons is notable in the superheavy elements with theatomic number Z ≥ 104. It is predicted that the inﬂuence is maximum in the group-12 element 112 Cn according to a theoretical calculation.1) In order to conﬁrm this prediction, we are planning chemical experiments on Hg as basic research for a chemical investigation of Cn. 203 Hg (T1/2 = 46.594 d) is a suitable radionuclide to conduct oﬀ-line experiments because it has a relatively long half-life and emits measurable γ-rays. A carrier-free 203 Hg tracer can be produced with the nat Tl + d reaction, but only the excitation functions of Pb and Tl isotopes obtained withthat reaction were measured in previous studies.2–4) In
this study, we measured the excitation function of the205
Tl(d, α)203 Hg reaction.
The production cross sections of 203 Hg were measured by means of a stacked foil technique. nat Tl2 O3pellets (96.5 mg cm−2 thick) were covered with 0.01mm-thick Al foil.
These pellets and nat Ti foils(0.02 mm thick) were alternately stacked as a target.
The nat Ti foils were used for monitoring the beam current and as an energy degrader. The target, ﬁxed in atarget holder, was irradiated with a 24-MeV deuteronbeam supplied from the RIKEN AVF cyclotron for
2.5 h in He gas. The beam current was measured witha Faraday cup connected to the target holder, and theaverage current was about 90 nA. The deuteron energies in the individual pellets and foils were calculatedwith LISE++ ver. 11.2.5) After irradiation, the produced nuclides were identiﬁed and quantiﬁed by γ-ray
spectrometry using Ge detectors.
Table 1 lists the identiﬁed nuclides and their nuclear
data.
When each of 203 Pb and 203 Hg disintegrates, γ-raysof 279 keV are emitted. The radioactivity of each nu-

Pb

102
203

Hg

101
100

0

- 180 -

20 30 40
Elapsed time / d5060

Fig. 1. Count rates of the 279 keV peak for one of the pellets. The solid curve indicates a fit of the experimental
values based on Eq. (1). The dashed lines indicate thecomponents of 203 Pb and 203 Hg.

clides can be determined by analyzing the change ofthe count rate of the 279 keV peak against elapsed
time because their half-lives are quite diﬀerent. The
obtained count rates of the 279 keV peak are shown in
Fig. 1.
The data in Fig. 1 can be ﬁtted with the following
equation:
Ctot = C0,Pb exp (−λPb t) + C0,Hg exp (−λHg t). (1)where C0,X and λX are the initial count rates and decay
constant of a nuclide X of interest, respectively, andt is the elapsed time from the end of bombardment.
The result of this analysis indicated that 203 Hg wascertainly produced. The analysis is performed for all
Tl pellets, and the determination of production crosssections of 203 Hg is in progress.
References

Graduate school of science and technology, Niigata University
RIKEN Nishina Center

101) A. Türler et al., Chem. Rev. 113, 1237 (2013).
2) R. Adam Rebeles et al., Nucl. Instrum. Methods Phys.
Res. B 288, 94 (2012).
3) R. Adam Rebeleset al., J. Korean Phys. Soc. 59, 1975 (2011).
4) J. W. Blue et al., J. Med. Phys. 5, 532 (1978).
5) O. B. Tarasov et al., Nucl. Instrum. Methods Phys. Res.
B 266, 4657 (2008).
6) C. J. Chiara et al., Nuclear Data Sheets 111, 141 (2010).
7) F. G. Kondev, Nuclear Data Sheets 105, 1 (2005).
8) S. Zhu et al., Nuclear Data Sheets 109, 699 (2008).
9) F. G. Kondev, Nuclear Data Sheets 108, 365 (2007).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Activation cross sections of alpha-induced reactions on natural
tungsten for 186 Re and 188 Re production
N. Ukon,∗1,∗2 M. Aikawa,∗3,∗4,∗2 M. Saito,∗4,∗2 T. Murata,∗4,∗2 Y. Komori,∗2 H. Haba,∗2 and S. Takács∗5
Radioisotopes (RI) are used for diagnosis and therapy in nuclear medicine. 186 Re is a β − emitter witha half-life of 3.72 days. Its maximum β − energy of
1.07 MeV has average penetration ranges of 1.1 mm insoft tissue and 0.5 mm in bone. It decays with the emission of γ-rays at 137 keV (Iγ = 9.47%). 188 Re is alsoa β − emitter with a half-life of 17 h and a maximum
β − energy of 2.12 MeV, and it decays with γ-ray emission at 155 keV (Iγ = 15.61%).1,2) Both isotopes can beused for theranostics investigations (therapy and diagnosis). We focused on processes to produce 186, 188 Re
through alpha-induced reactions on natural tungsten
because only one previous work with one data point
for both isotopes has been reported at an incident energy of 43 MeV.3) Therefore, we investigated the excitation function of the nat W(α, x)186, 188 Re reactions up
to 51 MeV.
The excitation functions of the nat W(α, x)186, 188 Re
reactions were measured using the stacked-foil technique, activation method, and high-resolution γ-ray
spectroscopy. nat W foils (purity: 99%, Goodfellow Co.,
Ltd., UK) were stacked with nat Ti foils (purity: 99%,
Goodfellow Co., Ltd., UK) for monitoring the beam
parameters and degrading the beam energy. The average thicknesses of the W and Ti foils were 29.99 and2.29 mg/cm2 , respectively. The irradiation was performed at the RIKEN AVF cyclotron. The target wasirradiated by an alpha-particle beam of 51 MeV withan average intensity of 189.1 pnA for 2 h. The incident beam energy was determined by the time-of-ﬂight
method using plastic scintillator monitors.4) The energy
loss of the beam in the stacked target was calculated using the SRIM code available online.5) The γ-ray spectraof the activated foils were measured using a high-purity
germanium (HPGe) detector. Nuclear decay data weretaken from the online NuDat 2.7 database.6)
From the net peak areas of the 137.16- and 155.04keV γ-rays, the activation cross sections for thenatW(α, x)186, 188 Re reaction were deduced using thestandard activation formula
σ=

∗2
∗3
∗4
∗5

Tγ the number of counts in the photo-peak, εd the detector eﬃciency, εγ the γ-ray abundances, εt the measurement dead time, λ the decay constant, tb the bombarding time, tc the cooling time, and tm the acquisitiontime.
We found that the only previous data point obtainedby Scott et al.3) for the nat W(α, x)186 Re reaction isapproximately half of our data. In contrast, for thenatW(α, x)188 Re reactions, the only data point of Scottet al.3) is more than double our result. The TENDL20197) predictions deviate considerably from the experimental data.
ReferencesTγ λ,εd εγ εt Nt Nb (1 − e−λt b)e−λt c(1 − e−λt m)where Nt denotes the surface density of target atoms,
Nb the number of bombarding particles per unit time,∗1

Fig. 1. Excitation functions of the nat W(α, x)186, 188 Re reactions. The results are compared with a previous study3)
and TENDL-2019.7)

Advanced Clinical Research Center, Fukushima Medical University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Institute for Nuclear Research, Debrecen, (ATOMKI)- 181 -

1) A. M. Denis-Bacelar et al., Eur. J. Nucl. Med. Mol. Imaging 44, 620 (2017).
2) I. G. Finlay et al., Lancet Oncol. 6, 392 (2005).
3) N. E. Scott et al., Nucl. Phys. A 119, 131 (1968).
4) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.,(2014), p. 3566.
5) J. F. Ziegler et al., SRIM: the Stopping and Range ofIons in Matter, http://www.srim.org/ .
6) National Nuclear Data Center: the NuDat2 database,
http://www.nndc.bnl.gov/nudat2/ .
7) A. J. Koning et al., TENDL-2019 nuclear data library,https://tendl.web.psi.ch/tendl_2019/tendl2019.html

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Activation cross sections of alpha particle-induced reactions on natural
hafnium up to 50 MeV†
S. Takács,∗1 M. Aikawa,∗2,∗3,∗4 M. Saito,∗2,∗3 T. Murata,∗2,∗3 N. Ukon,∗5,∗3 Y. Komori,∗3 and H. Haba∗3

†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 459, 50 (2019)
Institute for Nuclear Research, Hungarian Academy of Sciences
Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Advanced Clinical Research Center, Fukushima Medical University

450

nat

Hf(a,x)178W

400
350

Tárkányi 2014
This work
fit This work
TENDL-2017

300

Cross section (mb)

The 178m Ta (T1/2 = 9.31 min) radioisotope is suitable
for therapeutic applications owing to the high ionization capability of Kα1 and Kα2 radiation it emits (60%).
The distribution of the injected isotope in the humanbody can be tracked using a positron emission tomography (PET) camera by utilizing its partial positron decay mode (total β + decay: 1.24%). An alternative production route for the medically interesting 178m Ta radioisotope is the 178 W/178m Ta generator system. To
explore this possibility, activation cross sections of thenat
Hf(α, x)178 W (T1/2 = 21.6 d) reaction were investigated up to 50 MeV.
The experiment was performed at the RIKEN AVF
cyclotron. The stacked-foil activation technique andhigh-resolution γ-ray spectrometry were applied. The
stacked-foil target was assembled using pure metallic
foils of nat Hf and nat Ti from Nilaco Corp., Japan withaverage thicknesses of 10.34 and 5.34 µm, respectively.
Both the Hf and the Ti foils were inserted into the stackin pairs to compensate for the activity loss due to therecoil eﬀect. The target was irradiated with a 51.0MeV α-particle beam for 1 h. The incident beam energy
was measured using the time-of-ﬂight method.1) The energy loss of the bombarding alpha particles was calculated using the semi-empirical formula of Andersen andZiegler.2) The average beam intensity measured using a
Faraday cup was cross checked with the nat Ti(α, x)51 Cr
monitor reaction. The experimentally determined crosssections for the nat Ti(α, x)51 Cr monitor reaction agreed
perfectly with their recommended value3) ; therefore, theprimary beam parameters were accepted in further data
analysis. The γ-ray spectra of each irradiated foil wererecorded using a high-resolution high-purity germanium(HPGE) detector without chemical separation. Five series of gamma-ray measurements were performed withincreasing cooling times to observe the decay of the reaction products. Reaction and decay data for the data
analysis were taken from the NuDat 2.7 database.4)
The production of tungsten isotopes from 173 W to184
W was possible with the used alpha-particle parameters on a natural hafnium target. Due to limitation of
the used experimental technique and the decay parameters of those isotopes cross sections were derived only
for the 176, 177, 178 W radionuclides in our experiments.
As the radionuclide 178 W can be produced on all thesix stable isotopes of hafnium with the applied 51 MeV

250
200
150
100
50
0
20

25

30

35

40

45

50

Energy (MeV)

Fig. 1. Excitation function of the nat Hf(α, x)178 W reaction
in comparison with previous experimental data and theresult of the model calculation taken from the TENDL2017 database.5)

alpha-particle beam, the resulting excitation function
has a complex shape. The practical threshold energy ofthis process is approximately 20 MeV because the very
low yield of the 174 Hf(α, γ)178 W reaction did not provide a measurable contribution. Since no gamma emission follows the decay of 178 W the Eγ = 1340.85 andEγ = 1350.55 keV gamma lines of 178m Ta and its decay product were used in the data analysis. The appliedcooling time ensured the complete decay of the directly
produced 178m Ta and equilibrium between the decaying
178
W and 178m Ta.
The experimental data are in good agreement witheach other, while the TENDL-20175) prediction follows
the tendency of the experimental data up to 44 MeV.
In addition to the obtained cross sections of thenat
Hf(α, x)178 W reaction, cross sections for the nat Hf(α,176, 177W, nat Hf(α, x)175, 176, 177, 178g, 180g, 182g, 183 Ta,x)and nat Hf(α, x)173, 175, 179m2, 180m, 181 Hf processes were
determined. The results can contribute to develop the178
W/178m Ta generator system and to estimate the expected radio-impurity due to the co-production of otherradionuclides.
This work was conducted in the framework of aJapanese - Hungarian Research Cooperative Program
between JSPS and HAS.
References

1) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), (2014), p. 3566.
2) H. H. Andersen, J. F. Ziegler, Helium Stopping Powers
and Ranges in all Elements, (Pergamon, Oxford, 1997).
3) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
4) National Nuclear Data Center, The NuDat 2.7 database,
http://www.nndc.bnl.gov/nudat2/ .
5) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

- 182 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Activation cross sections of alpha-induced reactions on
natural ytterbium up to 50 MeV†
M. Saito,∗1,∗2 M. Aikawa,∗1,∗2,∗3 T. Murata,∗1,∗2 N. Ukon,∗4,∗2 Y. Komori,∗2 H. Haba,∗2 and S. Takács∗5
Many radioisotopes can be used for medical diagnosis and therapy. One candidate radioisotope is 177g Lu(T1/2 = 6.647 d).1) This radioisotope decays with emissions of a β-particle and γ-rays, which are useful fortherapy and diagnosis. For practical use of 177g Lu, thebest production reaction should be selected. Amongthe possible production reactions, we focused on thenat
Yb(α, x)177g Lu reaction in this study. Only one experimental study on this reaction was found in a literature survey.2) The study reported the production crosssections of 177g Lu up to 37.7 MeV. We investigated thecross sections of the reaction up to 50 MeV.
The experiment was performed at the RIKEN AVF
cyclotron. The stacked foil activation method and highresolution γ-ray spectrometry were used. The stacked
target consisted of pure metallic foils of nat Yb (99%purity, Goodfellow Co., Ltd., UK) and nat Ti (99.6%
purity, Nilaco Corp., Japan). The sizes and weights of
the Yb (3 pieces of 25 × 25 mm2 ) and Ti (1 piece of
50 × 100 mm2 ) foils were measured for determination of
the target thicknesses. The average thicknesses of thefoils were found to be 16.60, 16.32, and 17.11 mg/cm2
for the Yb foils and 2.40 mg/cm2 for the Ti foil. The
foils were cut into small pieces of 8 × 8 mm2 to fit a target holder that also served as a Faraday cup. The target was irradiated with a 51.0-MeV α beam for 2 hours.
The incident beam energy was measured by the timeof-flight method.3) Energy degradation in the target
was calculated by the SRIM code.4) The average beam
intensity measured by the Faraday cup was 414 nA.
The γ-ray spectra of each irradiated foil were measured
by a high-resolution HPGe detector without chemical
separation. Reaction and decay data were taken from
NuDat 2.7 for the data analysis.5)
The excitation function of the nat Ti(α, x)51 Cr monitor reaction was derived from measurements of the320.08-keV γ rays emitted after decay of 51 Cr (T1/2 =27.7025 d). The derived cross sections were comparedwith the IAEA recommended values.6) According to thecomparison, the adopted beam intensity was 379 nA, adecrease of 8.4% from the measured value.
Production cross sections of 177g Lu (T1/2 = 6.647 d)were derived from measurements of the γ line at
208.37 keV (Iγ = 10.36%) after a cooling time of 3.1
†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 453, 15 (2019)
Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Advanced Clinical Research Center, Fukushima Medical University
Institute for Nuclear Research- 183 -

Fig. 1. Excitation function of the nat Yb(α, x)177g Lu reaction in comparison with previous experimental data2)
and the TENDL-2017 data prediction.7)

days. Its parent radionuclide 177 Yb (T1/2 = 1.911 h)
decayed during the cooling time. The contribution of177m
Lu (T1/2 = 160.44 d) was estimated using the measurement series after a cooling time of 143 days and wasfound to be negligibly small. The cumulative cross sections of the nat Yb(α, x)177g Lu reaction were derived andcompared with the previous study2) and the TENDL2017 data,7) as shown in Fig. 1. The experimental
data are in good agreement with each other, but the
TENDL-2017 data are much lower than the previous
and our experimental ones.
In addition to 177g Lu, production cross sections of co-produced radionuclides 170, 171, 172, 173, 175 Hf,
171g, 172g, 173
Lu, and 169g Yb were determined. The results are useful to evaluate radionuclidic impurities of
177g
Lu for its practical application.
This work was supported by Hokkaido University Nitobe School Advanced Program Research Grant and
JSPS KAKENHI Grant Number 17K07004.
References
1) K. Rahbar et al., J. Nucl. Med. 58, 85 (2017).
2) B. Király et al., Nucl. Instrum. Methods Phys. Res. B
266, 3919 (2008).
3) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), (2014) p. 3566.
4) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
5) National Nuclear Data Center, The NuDat 2.7 database,
http://www.nndc.bnl.gov/nudat2/ .
6) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
7) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Measurement of excitation functions for 165 Ho(α, xn)165–168 Tm reactions
A. R. Usman,∗1,∗2 M. U. Khandaker,∗1,∗3 H. Haba,∗1 N. Otuka,∗1,∗4 and M. Murakami∗1
Currently, therapeutic radioisotopes are predominantly produced via the (n, γ) reactions routes. However, charged-particle-induced nuclear reactions serve as
good alternatives to produce these radioisotopes withhigh specific activities. The irradiation of holmium (Ho)with alpha-particle beams leads to the production ofseveral important thulium (Tm) radioisotopes for applications in nuclear medicine. In addition to the use of167
Tm as a skeletal imaging agent, the radioisotope wasreported to be useful for studying bone and tumour.1)
Furthermore, the Auger electrons as well as low-energy
γ- and X-rays emitted from the moderately long-lived167
Tm (9.25 days) are suitable for radiotherapy.2,3) On
the other hand, 165 Tm (1.25 days) has been considered
as a potential replacement of the popular 167 Tm owing
to its desirable decay characteristics.
A comprehensive analysis of all previous measurements of alpha-particle-induced reactions on holmium
shows large and unacceptable discrepancies. In thiswork, new measurements have therefore been made witha relatively large number of holmium foils to explore theexcitation functions at various energy points.
The overall procedure employed in the present work issimilar to that of our previous studies.4–6) The stacked
target foils were irradiated with a beam of alphaparticles, and the foils were subjected to gamma-ray
spectrometry to determine the production cross sections.
Thin metallic holmium foils (purity: 99%, thickness:
12.29 µm, supplier: Goodfellow, UK) served as the target. There is only one isotope, 165 Ho (100%), in natural
holmium. Natural copper foils and natural titanium foils
served as degraders of the beam energy and were used for
1200

165 Ho(α,4n) 165 Tm

Tarkanyi et al., '10

Cross section (mb)

1000

Gadkari et al., '97
Singh, '92

800

Mukherjee et al., '91
Sau et al., '68

600

Martin and Pilger, '66
RamaRao et al., '87

400

TENDL-2019
This work

200

0

∗2
∗3
∗4

monitoring of beam the intensity. A 50.4 MeV beam extracted from the RIKEN AVF cyclotron was focused ontarget foils of 9-mm diameter. The stack was irradiatedfor 2.0 h with a beam intensity of 5.45 × 1011 alphas/s.
The beam intensity was determined from the activitiesof 51 Cr produced from the nat Ti(α, x)51 Cr monitor reaction, for which the cross section recommended by the
IAEA (σ = 26.4 mb at Eα = 50 MeV) was adopted.
The measured production cross sections were calculatedusing the well-known activation equation.6)
Owing to space constraints, only the excitation function of 165 Tm and its thick target yield are presented in this report. 165 Tm is populated through the165
Ho(α, 4n)165 Tm reaction. 165 Tm (30.06 hours) decays via the EC + β + (100%) process to 165 Er. The
cross sections of this radioisotope were measured via
its relatively intense gamma line of Eγ = 242.917 keV(Iγ = 35.5%).
The physical thick target yield has been calculated forthe investigated radioisotope using the interpolation of
the measured production cross sections by spline fits aswell as the stopping power calculated using SRIM code.
In conclusion, new cross sections have been investigated for the 165 Ho(α, 4n)165 Tm, 165 Ho(α, 3n)166 Tm,
165
Ho(α, 2n)167 Tm, and 165 Ho(α, n)168 Tm reactions,but in this short report, only the results for 165 Tm havebeen presented.
References

20

25

30

35

40

45

50

55

Incident alpha energy (MeV)60

Fig. 1. Excitation function of the 165 Ho(α, 4n)165 Tm reaction.
∗1

Fig. 2. Integral thick target yield for 165 Tm.

RIKEN Nishina Center
Department of Physics, Umaru Musa Yar’adua University
Center for Biomedical Physics, Sunway University
Nuclear Data Section, International Atomic Energy Agency

1) R. Chandra et al., Radiol. 100, 687 (1971).
2) F. Tárkárnyi et al., Appl. Radiat. Isot. 68, 404 (2010).
3) M. Sadeghi et al., J. Radioanal. Nucl. Chem. 291, 731(2012).
4) A. R. Usman et al., Nucl. Instrum. Methods Phys. Res.
B 368, 112 (2016).
5) A. R. Usman et al., Nucl. Instrum. Methods Phys. Res.
B 399, 34 (2017).
6) A. R. Usman, et al., Appl. Radiat. Isot. 114, 104 (2016).

- 184 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Production cross sections of (d, x) reactions on natural erbium†
M. U. Khandaker∗1,∗2 and H. Haba∗2
Nowadays, radionuclides find wide applications invarious field such as medicine, industry, agriculture etc.
The production of such radionuclides is performed via
a number of processes, mostly via the use of particle
accelerators and nuclear reactors. Although the use ofparticle accelerators show some advantages over the nuclear reactors, however the production of radionuclides
via former process is still not well practiced. The nuclear reaction cross-sections play a key role in optimization of production parameters for radionuclide of interest via the use of particle accelerators. Present study
concerns the measurement of production cross-sectionsof residual radionuclides via deuteron irradiation on
natural erbium target in the energy range of 4.59–
23.06 MeV. This rare earth metal can also be used as apotential material for the production of some medicallyimportant thulium and erbium radionuclides. As an example, the production of the 167 Tm finds applications
as a tracer for tumor and bone studies by using both
the Anger/gamma camera and the rectilinear scanner.1)
Furthermore, it’s relatively long half-life (T1/2 = 9.25 d)and emission of γ-ray (Eγ = 207.801 keV, Iγ = 42%)and Auger electrons (Auger L = 5.5 keV, 114%) made it
suitable for applications in radionuclide therapy.2) Notethat considering the common drawbacks of (n, γ) production route (carrier added and low specific activity
production), several authors3) studied the production
possibility of thulium radionuclides via light-charged
particles-induced reactions on several targets. However, since a search of literature shows that the status
of deuteron-induced reaction cross-sections on erbium

Fig. 2. Thick target integral yields (physical) for 167, 168 Tm
radionuclides.

is not satisfactory, further study on such processes may
find great significance in various respect.
In these circumstances, this study forms an interest to measure the production cross-sections ofnat
Er(d, x)163, 165, 166, 167, 168 Tm and nat Er(d, x)171 Er
nuclear processes from their respective thresholds up to
23.06 MeV by using the AVF cyclotron of the RIKEN
RI Beam Factory, Wako, Japan. Details on the irradiation technique, radioactivity determination, and data
evaluation procedures are available in Ref. 4) Owing to
the space limitation of this report, we present only thenatEr(d, x)167 Tm cross sections and the deduced yieldin Figs. 1 and 2, respectively. Measured cross sections
with an overall uncertainty of better than 33% are listed
in Ref. 4). The cross-sections were normalized by using
the nat Ti(d, x)48 V monitor cross sections recommended
by IAEA. Measured data were critically compared withthe available literature data, and an overall good agreement was found. However, only partial agreements wereobtained with the data extracted from the TENDL2017 library and Empire-3.2.2 code.
The deduced thick-target yields indicate that a low
amount of no-carrier-added radioactivity of 167 Tm(4.2 MBq/µA-h) could be obtained by irradiating an enriched 167 Er target with 15-MeV deuteron energy froma cyclotron.
References

Fig. 1. Excitation function of the nat Er(d, x)167 Tm reaction.
†∗1∗2

Condensed from Nucl. Instrum. Methods Phys. Res. B 470,
1 (2020)
Centre for Biomedical Physics, Sunway University
RIKEN Nishina Center- 185 -

1) D. G. Medvedev, L. F. Mausner, G. A. Greene,
A. L. Hanson, Appl. Radiat. Isot. 66, 1300 (2008).
2) H. Uusijarvi, P. Bernhardt et al., J. Nucl. Med. 47, 807(2006).
3) F. Tarkanyi, A. Hermanne, F. Ditroi, S. Takacs, Appl.
Radiat. Isot. 135, 67 (2018).
4) M. U. Khandaker, H. Haba et al., Nucl. Instrum. Methods Phys. Res. B 470, 1 (2020).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Activation-cross-section measurement of alpha-induced reactions on
natural dysprosium
T. Murata,∗1,∗2 M. Aikawa,∗1,∗2,∗3 M. Sakaguchi,∗1,∗2 H. Haba,∗2 Y. Komori,∗2 Z. Szűcs,∗4 F. Ditrói,∗4 andS. Takács∗4
Holmium-166 can be used for a liver-cancer treatment
called radioembolization.1) It is worthwhile to investigate the most eﬃcient method for 166 Ho production bycomparing possible production reactions. The alphainduced reaction on dysprosium is one of them. However, there are no available experimental data for thisreaction. Thus, we were motivated to perform an experiment for the nat Dy(α, x)166 Ho reaction.
The experiment was performed using the AVF cyclotron at the RIKEN Beam Factory (Wako, Saitama,
Japan). The stacked-foil activation technique and highresolution γ-ray spectrometry were used to measure thecross sections of generated radionuclides. The stackedfoil target consisted of natural dysprosium (99% purity,
Goodfellow Co., Ltd., UK) and natural titanium (99.6%
purity, Nilaco Corp., Japan). The sizes and weights
of both foils were measured, and the derived average
thicknesses of the natural dysprosium and natural titanium foils were 23.6 µm and 5.1 µm, respectively. Bothfoils were cut into pieces of 8 × 8 mm2 size and inserted into the target holder, which served as a Faradaycup. The target was irradiated with a 50.6-MeV alphabeam. The measured beam intensity was 103.8 pnA.
The beam energy was measured using the time-of-ﬂight(TOF) method.2) The energy degradation in the target
was calculated using the stopping powers obtained from
SRIM code.3)
After one-hour irradiation, the target was removed
from the target holder for oﬀ-line γ-ray spectrometry

Fig. 1. Comparison of the excitation function of thenatTi(α, x)51 Cr monitor reaction with IAEA’s recommended values.4)
∗1
∗2
∗3
∗4

Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of science, Hokkaido Unviersity
Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI)

Fig. 2. Comparison of the excitation function of thenatDy(α, x)166 Ho reaction with the TENDL-2017 data.5)

using a high-purity germanium (HPGe) detector. The
320.08-keV γ-line (T1/2 = 27.704 d, Iγ = 9.91%) wasused to derive the cross sections of the nat Ti(α, x)51 Cr
monitor reaction.
Because the cross sections of the monitor reaction
were signiﬁcantly diﬀerent from IAEA’s recommended
values,4) an elemental analysis of the dysprosium foil was
conducted via scanning electron microscopy with energy
dispersive spectroscopy (SEM-EDS) using JSM-6610LA
with JED-2300, JEOL Ltd. at Hokkaido Research Organization. The foil was found to contain 4.27% oxygenby mass. The stopping power of natural dysprosium was
modiﬁed by considering the oxygen compounds. Consequently, the excitation function of the nat Ti(α, x)51 Cr
reaction showed good agreement with the recommended
values4) as shown in Fig. 1. The beam intensity wascorrected by −4% from the measured one.
The γ-line of 80.576 keV (T1/2 = 26.824 h, Iγ =6.56%) was used to derive the excitation function of
the nat Dy(α, x)166 Ho reaction. The result is shown in
Fig. 2 with the TENDL-2017 data.5) It was found that
the TENDL-2017 data5) signiﬁcantly underestimate thecross sections of this reaction.
The production of the radioactive by-products, suchas 167 Ho (T1/2 = 3.003 h), is being analyzed. The results
will be published in a forthcoming paper.
References

1) M. Reinders et al., Semin. Nucl. Med. 49, 237 (2019).
2) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), (2014), p. 3566.
3) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res. B
268, 1818 (2010).
4) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
5) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).

- 186 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Production cross sections of 157 Dy in alpha-particle-induced reactions
on natural gadolinium
D. Ichinkhorloo,∗1,∗2,∗3 M. Aikawa,∗1,∗4,∗3 Ts. Zolbadral,∗4,∗2,∗3 T. Murata,∗4,∗3 M. Sakaguchi,∗4,∗3
Y. Komori,∗3 T. Yokokita,∗3 and H. Haba∗3
The radioisotope dysprosium-157 (T1/2 = 8.14 h)
can be used for bone scanning (skeletal imaging).1)
This radionuclide can be produced through chargedparticle-induced reactions on natural gadolinium. In
this work, the production cross sections of 157 Dy in thealpha-particle-induced reactions on natural gadolinium
were studied. No previous experimental data were
found in a literature survey. The results were compared with TENDL-2017 data.2)
The experiment was performed at the RIKEN AVF
cyclotron. In the experiment, we used the stacked foil
technique, the activation method, and high-resolution
γ-ray spectrometry to determine the activation crosssections.
The stacked target consisted of 8 × 8 mm2 foils cut
from a larger Gd foil (25 µm, 50 × 50 mm2 , 99.9%
purity, Nilaco Corp., Japan) and Ti foils (5 µm, 50 ×
100 mm2 , 99.6% purity, Nilaco Corp., Japan). The
isotopic composition of the natural Gd target is 152 Gd(0.2%), 154 Gd (2.2%), 155 Gd (14.8%), 156 Gd (20.5%),
157
Gd (15.7%), 158 Gd (24.8%), and 160 Gd (21.8%).
The sizes and weights of the larger foils were measured to derive the average thickness. The thicknessof the Gd and Ti foils were found to be 25.4 and2.29 mg/cm2 , respectively. The Ti foils were used toassess beam parameters and target thicknesses using
the nat Ti(α, x)51 Cr monitor reaction. The cut foils
were stacked in a target holder, which also served as a
Faraday cup.
The alpha-particle beam was accelerated to51.1 MeV by the RIKEN AVF cyclotron.
Thebeam energy was measured using the time-of-ﬂight
method.3) The stacked target was irradiated for 60 min
with an average beam intensity of 257.6 nA. The beam
intensity was measured using the Faraday cup. Energy
degradation in the stacked target was calculated using
SRIM code.4)
The γ-rays emitted from the irradiated foils were
measured using a high-resolution high-purity germanium (HPGe) detector. The γ-ray spectra were analyzed using the software Gamma Studio (SEIKO
EG&G). The γ-rays at 326.3 keV (Iγ = 93%) emitted
after the decay of 157 Dy (T1/2 = 8.14 h) was measured
to derive the cross sections of the nat Gd(α, x)157 Dy
∗1
∗2
∗3
∗4
∗5

Faculty of Science, Hokkaido University
Nuclear Research Center, National University of Mongolia
Nishina Center for Accelerator-Based Science, RIKEN
Graduate School of Biomedical Science and Engineering,
Hokkaido University
School of Science, Hokkaido University- 187 -

Fig. 1. Excitation function of the nat Gd(α, x)157 Dy reaction.

reaction. The measurements were performed after acooling time of 15 h.
The total uncertainties (8.8%) were estimated fromthe square root of the quadratic summation of eachcomponent: statistical uncertainty (1.5%), target
thickness (2%), target purity (1%), beam intensity(5%), detector eﬃciency (6%), and γ -ray intensity(3.2%).
The cross sections derived from the activity of 157 Dy
are presented in comparison with TENDL-2017 data2)
in Fig. 1. The TENDL-2017 data underestimate ourexperimental cross sections.
In summary, we have performed an experiment tomeasure the activation cross sections of alpha-particleinduced reactions on nat Gd up to 51 MeV at the
RIKEN AVF cyclotron. In this work, the production
cross sections of 157 Dy were determined, and the results were compared with the prediction of TALYSbased model calculation, for which data were takenfrom the TENDL-2017 online database.
This work was supported by JSPS KAKENHI Grant
Number 17K07004.
References
1) G. Subramanian et al., J. Nucl. Med. 12, 558 (1971).
2) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
3) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC 2014), 3566 (2014).
4) J. F. Ziegler et al., SRIM: the Stopping and Range ofIons in Matter, http://www.srim.org .

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Activation cross sections of alpha-particle induced nuclear reactions
on natural palladium†
M. Aikawa,∗1,∗2 M. Saito,∗3,∗2,∗4 Y. Komori,∗2 H. Haba,∗2 S. Takács,∗5 F. Ditrói,∗5 and Z. Szücs∗5

†
∗1
∗2
∗3
∗4
∗5

14

nat

12
Cross section (mb)

Production cross sections of radioactive isotopes (RI)
are fundamental information for medical applications
such as therapy and diagnostics. One of the medical RI
is 103 Pd (T1/2 = 16.991 d), which is used for brachytherapy1) and targeted radionuclide therapy as part of the103
Pd/103m Rh in vivo generator.2) In addition to thedirect production of 103 Pd, the contribution from thedecay of its parent, 103g Ag, is worthy of investigation.
There are several charged-particle-induced reactions to
produce 103 Ag. In a literature survey, only one experimental study of 103g Ag production cross sections of
α-induced reactions on nat Pd was found.3) The incident energy of the previous study is limited to below
37 MeV and even lower than that at the peak of thecross sections. Therefore, we are motivated to perform
an experiment to determine the excitation function of
the nat Pd(α, x)103g Ag reaction up to 50 MeV.
The experiment was performed at the RIKEN AVF
cyclotron. The stacked-foil activation technique andhigh-resolution γ-ray spectrometry were used. Thin
metallic foils of nat Pd (99.95% purity, Nilaco Corp.,
Japan) and nat Ti (99.9% purity, Goodfellow Co., Ltd.,UK) were purchased to fabricate a target. The size andweight of the large foils were measured. The average
thicknesses of the Pd and Ti foils were found to be 9.70
and 4.85 mg/cm2 from the measurement, respectively.
The foils were cut into small pieces of 10 × 10 mm2
to fit a target holder. The stacked target consisted of
12 sets of the group of Pd-Pd-Ti-Ti foils. The target
was irradiated for 2 h by a 51.2-MeV α beam with anaverage intensity of 111.4 nA. The intensity was measured using a Faraday cup. The initial beam energy
was determined using the time-of-flight method.4) The
energy degradation of the beam in the target was calculated using the polynomial approximation of stoppingpower data.5) Gamma-ray spectra from each irradiatedfoil were measured four times to follow the decay of thereaction products with half-lives between 50 min and
460 days. Nuclear-decay data were taken from NuDat
2.7.6)
The 118.74-keV γ rays (Iγ = 31.2%) emitted withthe decay of 103g Ag (T1/2 = 65.7 min) were measured
after a cooling time of 3.6 h. There are minor contributions to the photo-peak area from co-produced isotopes,
Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 449, 99 (2019)
Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Science, Hokkaido University
Present address: Graduate School of Biomedical Science andEngineering, Hokkaido University
Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI)- 188 -

Pd(α,x)103gAg

Hermanne 2005
TENDL2017
This work

10
8
6
4
2
0

25

30

35
40
Energy (MeV)45

50

Fig. 1. Cumulative cross sections of the nat Pd(α, x)103g Ag
reaction.

100

Pd and 111m Pd, but their total contribution is negligibly small. The measured counts are used to determine the excitation function of the nat Pd(α, x)103g Ag
reaction. In addition to the direct production, there
are contributions from the decay of its isometric state(T1/2 = 5.7 s) and 103 Cd (T1/2 = 7.3 min). Therefore,
cumulative cross sections are derived in this work. The
result is shown in Fig. 1 in comparison with the experimental data obtained earlier3) and the TENDL-2017
data.7) Our result is slightly higher than the previous
experimental data. The TENDL-2017 data provides an
excitation function with a consistent tendency.
Our result extends cross-section data to the higher
energy region and covers the peak. It enriches nuclear
reaction databases and is available for development oftheoretical calculation models.
This work is supported by the Japan - Hungary Research Cooperative Program, JSPS and HAS and by
JSPS KAKENHI Grant Number 17K07004.
References
1) S. Nag et al., Int. J. Radiat. Oncol. Biol. Phys. 44, 789(1999).
2) Z. Szucs et al., Radiochim. Acta 92, 215 (2004).
3) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 229, 321 (2005).
4) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), (2014), p. 3566.
5) J. F. Ziegler et al., SRIM: the Stopping and Range ofIons in Matter (2008).
6) National Nuclear Data Center, The NuDat 2.7 database,
http://www.nndc.bnl.gov/nudat2/ .
7) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Excitation function measurement for zirconium-89 and niobium-90
production using alpha-induced reactions on yttrium-89†
T. Murata,∗1,∗2 M. Aikawa,∗1,∗2,∗3 M. Saito,∗1,∗2 H. Haba,∗2 Y. Komori,∗2 N. Ukon,∗4,∗2 S. Takács,∗5 and
F. Ditrói∗5
Zirconium-89 (T1/2 = 78.41 h) and niobium-90(T1/2 = 14.6 h) are expected to be used for immunoPET.1,2) From the viewpoint of radionuclide production,
the investigation of eﬀective production reactions is valuable. We focused on the α-induced reactions on themonoisotopic element 89 Y to produce the two radionuclides. Five experimental studies on these reactions3–5)
were found in a literature survey. However, signiﬁcantdiscrepancies exist among the experimental data. Therefore, we were motivated to investigate α-induced reactions on 89 Y. The cross sections of co-produced radionuclides other than 89 Zr and 90 Nb were also determined.
The experiment was performed at the RIKEN AVF cyclotron. The stacked foil activation technique and highresolution γ-ray spectrometry, which are well-establishedmethods, were adopted for the experiment. The target
was composed of pure metallic foils of 89 Y (99% purity,
Goodfellow Co., Ltd., UK), nat Ti (99.6% purity, Nilaco
Corp., Japan), and 27 Al (> 99% purity, Nilaco Corp.,
Japan). The sizes and weights of the foils were measured
to determine their average thicknesses, which were foundto be 24.2, 5.1, and 5.5 µm for Y, Ti, and Al, respectively.
The three foils were cut into a small size of 1 cm × 1 cm
to ﬁt a target holder, which also served as a Faraday cup.
The stacked target was irradiated with a 50.9 ± 0.1-MeV
M-beam for 1 h. The incident energy of the beam wasmeasured using the time-of-ﬂight method.6) The energy
degradation in the target was calculated using stopping
powers obtained from the Stopping and Range of Ionsin Matter (SRIM) code.7) The average beam intensity
was measured as 411 nA using the Faraday cup. The
irradiated stacks were dismantled for the oﬀ-line γ-ray
spectrometry using HPGe detectors. The dead time was
kept under 10% by adjusting the distances between themeasured foil and HPGe detector. Reaction and decay
data for the γ-ray spectrometry were taken from NuDat
2.7.8)The beam parameters were veriﬁed using the27
Al(α, x)22 Na and nat Ti(α, x)51 Cr monitor reactions
in comparison with the IAEA recommended values.9)
Based on the comparison, the beam intensity was decreased by 4% from the measured value. The corrected
intensity of 398 nA was adopted to derive cross sections.
The excitation function of the 89 Y(α, x)89g Zr reaction
†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 458, 21 (2019)
Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Advanced Clinical Research Center, Fukushima Medical University
Institute for Nuclear Research, Hungarian Academy of Sciences

Fig. 1. Comparison of cumulative cross sections of the89
Y(α, x)89g Zr reaction with previously reported data3–5)
and TENDL-2017 data.10)

was determined. The measurement of the 909.15-keV γrays (T1/2 = 78.41 h, Iγ = 99.04%) was performed after
a cooling time of 10 days, which was long enough forcomplete decay of the parent nuclei 89g, m Nb and 89m Zr.
The cumulative cross sections of 89g Zr were obtained andcompared with three previous studies3–5) and TENDL2017 data10) in Fig. 1. One of the three experimental
data sets3) agree with our result. However, the others4,5)
deviate from ours.
In addition to 89g Zr, the production cross sectionsof 90 Nb and other co-produced radionuclides were determined and compared with previous studies and the
TENDL-2017 data. Our results are reasonably consistent with some of the previous studies.
This work was supported by JSPS KAKENHI Grant
Number 17K07004.
References

1) M. A. Deri et al., Nucl. Med. Biol. 40, 3 (2013).
2) V. Radchenko et al., Radiochim. Acta 102, 433 (2014).
3) V. N. Levkovski, Cross Sections of Medium Mass Nuclide
Activation (A = 40–100) by medium energy protons andalpha particles (E = 10–50 MeV) (Inter-Vesi, Moscow,
USSR, 1991).
4) N. L. Singh et al., Phys. Scr. 61, 550 (2000).
5) M. Shahid et al., Nucl. Instrum. Methods Phys. Res. B
358, 160 (2015).
6) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566 (2014).
7) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
8) National Nuclear Data Center, The NuDat 2.7 database,
http://www.nndc.bnl.gov/nudat2/ .
9) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
10) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

- 189 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Production cross sections of 68 Ga via deuteron-induced reactions on
natural zinc
Ts. Zolbadral,∗1,∗2 M. Aikawa,∗1,∗3,∗2 D. Ichinkhorloo,∗3,∗2 Kh. Tegshjargal,∗4 N. Javkhlantugs,∗4 Y. Komori,∗2
and H. Haba∗2
Ga (T1/2 = 68 min), a positron emitter, is a valuable medical isotope used for positron emission tomography (PET). One of the production routes of this radionuclide is the deuteron-induced reaction on zinc. In
a literature survey, only two datasets of the experimental cross sections of the nat Zn(d, x)68 Ga reaction were
found,1,2) and these data show a remarkable discrepancy. It is necessary to obtain reliable cross sections toinvestigate the best production route for practical use.
Therefore, we measured the production cross sectionsof 68 Ga via the deuteron-induced reaction on naturalzinc.
The stacked-foil activation method and γ-ray spectrometry were used. The stacked target was composedof metallic foils of nat Zn (17.64 mg/cm2 , 99.9% purity) and nat Ti (9.13 mg/cm2 , 99.6% purity). The target was irradiated for 22 min by a 24-MeV deuteronbeam from the RIKEN AVF cyclotron. The incident beam energy was measured using the time-ofﬂight method. The energy degradation in the stacked
foils was calculated using SRIM code.3) The beam intensity was measured using a Faraday cup and crosschecked using the nat Ti(d, x)48 V monitor reaction.4)
By referring to the cross sections of the monitor reaction, the beam intensity was increased 6.6% from themeasured value and thereby corrected to 102.4 nA.
The γ-ray spectra of the irradiated foils were measured using a high-resolution HPGe detector (ORTEC
68

Fig. 2. Integral yield of 68 Ga.

GMX30P4-70) without chemical separation. The detector was calibrated using a standard mixed multiple
γ-ray-emitting point source. The distance between thedetector and foils was chosen to keep the dead time lessthan 7%.
The cross sections of the nat Zn(d, x)68 Ga reaction
were derived from the measurements of the 1077.34keV γ-line (Iγ = 3.22%) associated with the 68 Ga decay. The excitation function of the reaction is shownin Fig. 1 in comparison with previous data1,2) and thetheoretical estimation of TENDL-2017.5) Our result is
consistent with the data reported by Šimečková et al.2)
but inconsistent with those reported by Nassiﬀ andMünzel1) in the whole investigated energy region. The
TENDL-2017 data overestimate the experimental dataaround the peak in the energy range of 8–18 MeV.
The physical yield of 68 Ga was deduced from themeasured cross sections. The derived yield is shown in
Fig. 2. The physical yield of 68 Ga via the deuteroninduced reaction on zinc is reported for the ﬁrst time.
This work is supported by JSPS KAKENHI Grant
Number 17 K07004. Ts.Z. was granted a scholarshipby the M-JEED project (Mongolian-Japan Engineering Education Development Program, J11B16).
References

Fig. 1. Excitation function of the nat Zn(d, x)68 Ga reaction.
∗1
∗2
∗3
∗4

Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
School of Engineering and Applied Sciences, National University of Mongolia- 190 -

1) S. J. Nassiﬀ, H. Münzel, Radiochem. Radioanal. Lett.
12, 353 (1972).
2) E. Šimečková et al., EPJ Web Conf. 146, 11034 (2017).
3) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
4) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
5) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Production cross sections of 45 Ti via deuteron-induced reaction on 45 Sc
Ts. Zolbadral,∗1,∗2 M. Aikawa,∗1,∗3,∗2 D. Ichinkhorloo,∗3,∗2 Kh. Tegshjargal,∗4 Y. Komori,∗2 H. Haba,∗2
S. Takács,∗5 F. Ditrói,∗5 and Z. Szücs∗5
The radionuclide 45 Ti (T1/2 = 184.8 min) is a positron
emitter (Eβ + = 439 keV, Iβ + = 84.8%) suitable forpositron emission tomography (PET). This radioisotope
can be produced in the deuteron-induced reaction on ascandium-45 target at cyclotrons. However, the quality of experimental data on the cross sections of the45
Sc(d, 2n)45 Ti reaction is not satisfactory. The main
purpose of this study is, therefore, to measure the crosssections of the 45 Sc(d, 2n)45 Ti reaction for 45 Ti production. In addition, the physical yield is derived from themeasured cross sections.
The stacked-foil activation technique and γ-ray spectrometry were adopted to determine the cross sections.
The stacked target consisted of metallic foils of 45 Sc(thicknesses of 7.71 mg/cm2 and 76.0 mg/cm2 with apurity of 99.0%), 27 Al (4.99 mg/cm2 , 99.6%), and nat Ti(9.13 mg/cm2 , 99.6%). The target was irradiated for
30 min with a 24-MeV deuteron beam from the RIKEN
AVF cyclotron. The incident beam energy was measured
by the time-of-flight method. The energy degradation in
the stacked target was calculated using the SRIM code.1)
The beam intensity was measured using a Faraday cup
and cross-checked with the nat Ti(d, x)48 V monitor reaction.2) According to the cross checking, the intensity(175.2 nA) was corrected by a decrease of 3% from themeasured value (180.3 nA). The γ-ray spectra of the irradiated foils were measured by a high-resolution andhigh-purity germanium (HPGe) detector. The detector
was calibrated by a standard mixed γ-ray point source.
The dead time was kept below 7% in the measurements.

Fig. 1. Excitation function of the 45 Sc(d, 2n)68 Ti reaction.
∗1
∗2
∗3
∗4
∗5

Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
School of Engineering and Applied Sciences, National University of Mongolia
Institute for Nuclear Research (ATOMKI), Hungary

Fig. 2. Physical yield of 45 Ti.

The cross sections of the 45 Sc(d, 2n)45 Ti reaction
were derived from the measurement of the 719.6-keV
γ-line (Iγ = 0.154%) associated with the 45 Ti decay.
The excitation function of the 45 Sc(d, 2n)45 Ti reaction
is shown in Fig. 1 in comparison with previous experimental data3) and the theoretical estimation fromTENDL-2017.4) The derived excitation function of the45
Sc(d, 2n)45 Ti reaction is consistent with the data reported by Hermanne et al.3) The peak position of the
TENDL-2017 data is slightly shifted to a lower energy.
The physical yield of 45 Ti was deduced from a spline
fitted curve of the measured excitation function andstopping power calculated from the SRIM code.1) The
derived yield is shown in Fig. 2. The present yield curveof 45 Ti is slightly higher than the experimental datameasured by Dmitriev et al.5) at 22 MeV. We confirmedthat no radioactive impurities of titanium are producedin the energy range below 15 MeV, which is the threshold energy of 44 Ti production. Above 15 MeV and up
to 24 MeV, the physical yield of 44 Ti is seven or moreorders of magnitude less than that of 45 Ti and negligibly
small. Thus, this reaction with chemical separation allows the production of high-specific-activity 45 Ti in thisenergy range.
This work is supported by JSPS KAKENHI Grant
Number 17 K07004. Ts.Z was granted a scholarship by
the M-JEED project (Mongolian-Japan Engineering Education Development Program, J11B16).
References

1) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res. B
268, 1818 (2010).
2) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
3) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 270, 106 (2012).
4) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
5) P. P. Dmitriev et al., INDC (CCP)-210, 1 (1983).

- 191 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Present status of 211 At production at the RIKEN AVF cyclotron
Y. Wang,∗1 N. Sato,∗1 Y. Komori,∗1 T. Yokokita,∗1 D. Mori,∗1 S. Usuda,∗1 and H. Haba∗1
211

At is one of the most promising radionuclides fortargeted alpha radiotherapy owing to its suitable halflife of T1/2 = 7.214 h and high alpha-particle emission
probability of 100%.1) We have been producing 211 At
via the 209 Bi(α, 2n)211 At reaction at the RIKEN AVF
cyclotron.2,3) In this paper, we report improved production technologies of 211 At, which could reduce theseparation time from 2 h to 1 h and yield a neutral dry
211
At product instead of the confused 211 At species inthe solution.
Figure 1 shows the production process for dry 211 At.
A metallic 209 Bi target (> 99.999%, 20 mg/cm2 ) was
prepared through vacuum evaporation on an Al plate(thickness: 1 mm). As shown in Fig. 1(a), the Bi target was placed at an angle of 15◦ with respect to thebeam axis. The target was cooled with water (10◦ C,
1.5 L/min) and He gas (30 L/min) during the irradiation. An alpha beam with an energy of 29.0 ± 0.2 MeV
was delivered from the RIKEN AVF cyclotron. The
precise beam energy was measured using a time-offlight detector.4) A beam-wobbling system was used torotate the beam spot on the target and to prevent heatconcentration. After the beam passed through a Be
window (18.1 µm) and He cooling gas (65 mm, 1.1 bar),
the beam energy on the target was 28.0 ± 0.2 MeV,
as calculated with LISE (ver. 11.0.72). The beam
intensity (4–32 µA) and irradiation time (2 to 8 h)
was varied to meet the users’ requirements. Subsequently, 211 At was separated from the Bi target byusing a dry distillation technique (see Fig. 1(b)). The
irradiated Bi target was placed on a copper tray in aquartz tube and heated up to 850◦ C in 10 min, following which it was kept for another 15 min and finallycooled down naturally. 211 At sublimated from the target was transported from the quartz tube through aquartz capillary (i.d. = 2 mm, length = 13 cm) to a
PFA cold trap (i.d. = 1 mm, length = 100 cm) by oxygen gas (10 mL/min). The PFA cold trap was cooled
to −96◦ C to collect the gaseous 211 At. As shown in
Fig. 1(c), after the distillation, the capillary and the
PFA trap tube were washed with chloroform (FUJIFILM Wako Pure Chemical Corporation, Cat. No.:033-15721, Infinity Pure, 200–400 µL). The eluate collected in a 1-mL V-shaped glass vial was then dried
up by dry N2 gas (100 mL/min) at room temperature(see Fig. 1(d)). The chemical yields of the dry 211 At
products were determined by measuring the 687 keV γ-ray (Iγ = 0.261%) with a Ge detector. The chemical
purity of the products and the decontamination factor of 209 Bi from 211 At were evaluated with chemical
analysis using inductively coupled plasma mass spec∗1

RIKEN Nishina Center- 192 -

Fig. 1. Production process of dry 211 At.

trometry (ICP-MS).
We confirmed that the radioactivities of 211 At produced in the targets agreed well with those estimatedfrom thick target yields in the literature.5) The atomic
ratio 210 At/211 At was determined to be less than
2.1 × 10−6 at the end of bombardment (EOB), which
satisfied the medical requirement of < 1 × 10−3 at
EOB.4) The typical chemical yield was 80%. The
chemical impurities (> 1 ng) in 200 µL of chloroform
were Cu (43.84 ng), Al (38.90 ng), Zn (23.55 ng), andBi (6.70 ng). The decontamination factor of 209 Bi fordry 211 At was determined to be 8.3 × 10−8 .
By using the current production technology of 211 At,
1 GBq of 211 At can be produced through 1.5-h irradiation with a 32-µA alpha beam (27.8 MeV on target).
Dry 211 At can be prepared 4 h after EOB. We havebeen distributing 211 At to 14 users in Japan for the
research and development of nuclear medicine.
References
1) M. Zalutsky et al., Curr. Radiopharm. 4, 177 (2011).
2) S. Yano et al., RIKEN Accel. Prog. Rep. 50, 263 (2017).
3) N. Sato et al., RIKEN Accel. Prog. Rep. 50, 262 (2017).
4) T. Watanabe et al., Proc. 12th Annual Meeting of Particle Accelerator Society of Japan, (2015), p. 1198.
5) A. Hermanne et al., Appl. Radiat. Isot. 63, 1 (2005).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Decontamination of Po in the 211 Rn/211 At generator system
K. Aoi,∗1,∗2 K. Kawasaki,∗1,∗2 S. Maruyama,∗1,∗2 M. Higashi,∗1,∗3 K. Washiyama,∗4 A. Yokoyama,∗1,∗3
I. Nishinaka,∗5 D. Mori,∗1 Y. Wang,∗1 and H. Haba∗1
The short path length and high linear energy transfer of α particles are expected to enable targeted alpha therapy for the treatment of tumor. A promising nuclide among various α emitters is 211 At with ahalf-life of 7.21 h, which has gained popularity owing
to its appropriate life and potential to synthesize labeled compounds as a halogen element. This has been
the motivation behind several preclinical studies on At
chemistry.1) To improve the availability of 211 At, thedevelopment of a 211 Rn/211 At generator would be useful for expanding nuclide production away from accelerator facilities because 211 Rn, which has a half-life of
14.6 h, is the parent nuclide of 211 At.2) However, Po
isotopes such as 207 Po and 206 Po, which are known tobe harmful to the human body, may contaminate theAt sample owing to decay from the Rn products. We
aim to study the wet chemistry processes by using adsorption chromatography resins for an At solution freefrom Po contamination.
In this study, 211 At was produced via the209
Bi(α, 2n) reaction at the RIKEN AVF cyclotron anddelivered to Kanazawa University. The irradiated Bi
target was dissolved in 2 mL of 6 M HNO3 and mixed
with 10 mL of H2 O to prepare a 1 M HNO3 solution,
2 mL of which was used to extract the 211 At nuclide
into 18 mL of dodecane solvent.
Aliquots of the dodecane solution were subjected
to back extractions into several solutions of various
HCl concentrations. 2 mL of each solution was fed toadsorption chromatography columns ﬁlled with eithera cation-exchange resin, DGA resin, or TEVA resin
through a conditioning process in advance. The eluted
solution from the column and the eluent due to additional washing with 2 mL of two solutions with thesame HCl concentration were subjected to liquid scintillation counter (LSC) measurement to determine the211
At radioactivity.
The results of the measurement of 211 At radioactivity after puriﬁcation with adsorption chromatography columns demonstrate that the recoveries for DGA
resin and cation-exchange resin were ca. 50% at mostat 0.01 M HCl and were better than that for TEVA
resin. This suggests that the species of At may have
∗1
∗2
∗3
∗4

∗5

Graduate School of Natural Science and Technology,
Kanazawa University
Institute and College of Science and Engineering, Kanazawa
University
Fukushima Global Medical Science Center, Fukushima Medical University
Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology
RIKEN Nishina Center- 193 -

Fig. 1. Recovery of 211 At radioactivity and elimination of
Po depending on the ascorbic-acid concentration.

a variety of oxidation states that aﬀect adsorption
in columns. Therefore, another experiment was performed to change their oxidation states by using a reductant agent and to conﬁrm the eﬀect of reduction
with cation-exchange resin.
Similarly to the experiment described above,
aliquots of the dodecane solution were subjected toback extractions into 0.01 M HCl solution, which had
been adjusted to the solutions with 0.01, 0.1, and 1%
ascorbic acid. The HCl solutions were fed to a column
ﬁlled with cation-exchange resin that was conditioned
well in advance. The eluent from the column was collected and subjected to the LSC measurement in thesame manner as above.
The recovery of 211 At radioactivity with ascorbic
acid as a reductant agent is shown in Fig. 1 together
with Po elimination data taken with the Po activity
produced in the JAEA tandem accelerator. It was
found that the 211 At recoveries are improved to 80%,and the elimination of Po was successful under thesame condition.
References

1) F. Guérard, J. -F. Gestin, M. W. Brechbiel, Cancer Biother. Radiopharm. 28, 1 (2013).
2) E. Maeda et al., J. Radioanal. Nucl. Chem. 303, 1465
(2015).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Separation and purification of 139 Ce tracer for metallofullerene synthesis
K. Akiyama,∗1,∗2 K. Amekura,∗1 and H. Haba∗2
Recently, clinical tests have been conducted on radionuclides of group 3 elements including lanthanides,
and some radionuclides were newly approved as radiopharmaceuticals. Metallofullerenes encapsulating lanthanide elements are attractive for application in electronic devices and pharmaceuticals. In particular, it isexpected that rich π electrons on a metallofullerene surface enable the production of various metallofullererene
derivatives by the addition of various functional groups
and that the encapsulation of radionuclides by thesederivatives could be applied as radiopharmaceuticals.
For such applications, excellent radionuclides, such as
139
Ce, emitting monochromatic γ rays and have a halflife of several months are required. In this paper, we
report the separation and puriﬁcation of a 139 Ce tracer
from its target material for metallofullerene synthesis.
Cerium-139 was produced from the 139 La(d, 2n)139 Cereaction using a nat La target irradiated with 5 µA of
24 MeV deuterons for 5 h at the RIKEN AVF cyclotron.
After the irradiation, the La target containig 139 Ce wasdissolved in nitric acid. For the separation and puriﬁcation of 139 Ce from La, the solvent extraction method was
employed and was executed according to the procedureshown in the Fig. 1. The solution samples obtained in aseries of this extraction procedure were measured using a
Ge semiconductor detector to check the remaining 139 Ce
radioactivity in each sample.
The remaining amounts of the target material La andoxidant Cr were determined by optical absorption measurement and were found to be 2.1% and 3.9%, respec-

Fig. 1. Schematic diagram of 139 Ce separation from a of La
target.
∗1∗2

Department of Chemistry, Tokyo Metropolitan University
RIKEN Nishina Center

Fig. 2. HPLC elution behavior of 139 Ce metallofullerene
together with UV-monitored chromatogram of metallofullerenes produced in this study.

tively. The amount of remaining La in a single separation
process is still much larger than the amount of the 139 Ce
tracer. However, it has been found that by repeating
this separation procedure, it would be possible to obtaina suﬃciently puriﬁed 139 Ce tracer.
As mentioned above, the separated 139 Ce tracer still
includes large amounts of La and Cr. However, if theamounts of these impurities are suﬃciently small relative to that of the added carrier element and do notaﬀect the fullerene production, the purity of 139 Ce canbe said to be suﬃcient in this experiment. To conﬁrm
this, Tb4 O7 was added to a 139 Ce tracer solution, andthis solution was employed for the metallofullerene production under the same conditions as those previously
reported.1) In Fig. 2, the high-performance liquid chromatography (HPLC) elution behavior of 139 Ce metallofullerene (open circles) on a Buckyprep column (Nacalai
Tesque, Inc., eﬂuent: tolunene) is shown together with achromatogram aquired using UV absorption (gray solidline). The most dominant elution peak found in both
chromatograms are due to M@C82 .2) It is reported thatthe HPLC retention time of M@C82 on a buckyprep
column increases as the atomic number of the encapsulated lanthanide atom increased.3) The observed UVmonitored HPLC elution peak around 60 min occurs after that of Ce metallofullerene and is considered to be
derived from Tb@C82 because no HPLC elution peakwith suﬃcient intensity and faster retenton time thanthat of Ce@C82 is observed. In conclusion, the observed
elution peak is derived from Tb@C82 and the amount of
the remaning La with this separation method is foundto be suﬃciently small.
References

1) K. Akiyama et al., RIKEN Accel. Prog. Rep. 49, 243 (2016).
2) H. Shinohara et al., Rep. Prog. Phys. 63, 843 (2000).
3) D. Fuchs et al., J. Phys. Chem. 100, 725 (1996).

- 194 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Separation of 121m Te from antimony without redox reaction
T. Kubota,∗1,∗2 S. Fukutani,∗1 T. Takahashi,∗1 H. Haba,∗2 D. Mori,∗2 and S. Takahashi∗1
Radioactive tellurium isotopes, such as 129 Te, 131 Te,
and 132 Te, were released in the Fukushima Dai-ichi
nuclear accident and are regarded as signiﬁcant for
the evaluation of exposure dose during 2011. Owing
to their short half-life, radioactive materials derived
from the accident have already decayed out; thus, theevaluation requires some laboratory experiments. In
experiments where radio nuclides are added to plant
and animal samples, carrier-free and high-purity tracers should be employed to avoid undesirable chemical
eﬀects. The production of a suitable tracer had been
investigated in previous reports where radioactive tellurium generated by the bombardment of Sb2 O3 with
deuteron at an energy of 24 MeV was puriﬁed througha redox reaction.1,2) However, this method generates
toxic chlorine gas. More moderate methods, therefore,should be developed.
We found that tellurium is separated as a cationfrom anionic antimony through anion exchange chromatography. Chemical species of both elements were
calculated under several conditions, following which
tellurium was separated using the calculation results.
Tellurium and antimony exist as chloro-complex anions in a high-concentration HCl solution. With increasing pH, Te(IV) is converted into TeOOH+ , while
Sb(III) forms a precipitate. Through this precipitation, a large part of tellurium is co-precipitated. We
considered that tellurium can be puriﬁed with careful
control of the pH and HCl concentration, and we investigated the optimal conditions using Medusa-Hydrachemical equilibrium software for Windows.3) The calculation results are shown below. Te(IV) was converted into TeOOH+ at pH > −0.2 and [HCl] < 1.6 M.
Sb(III) remained as a solution at pH < −0.5 and [HCl]> 3.2 M with [Sb] = 200 mM, which is equivalent to
900 mg Sb2 O3 dissolved in 30 mL HCl and to a concentration derived from ordinary production at one time.
At this antimony concentration, tellurium cannot be
puriﬁed. Based on the fact that the solubility of antimony depends on its concentration, the maximum concentration of antimony at pH = −0.2 without precipitation was calculated to be 7 mM. In order to ensurethat the puriﬁcation was conducted without precipitation, we applied a concentration of 5 mM Sb.
An irradiated Sb2 O3 pellet was dissolved in concentrated HCl, following which insoluble antimony was removed by centrifugation. The supernatant was diluted
with H2 O to 2.4 M HCl and 5 mM Sb solution. The solution was loaded onto anion exchange resin (AG1x8,∗1∗2

Institute for Integrated Radiation and Nuclear Science, Kyoto University
RIKEN Nishina Center- 195 -

Fig. 1. Elution (□) and total recovery ratio (⃝) of tellurium from antimony (5 mM) with 1.6 M HCl.

Cl-form, 100–200 mesh, 10 mL), following which Te121m was eluted with 1.6 M HCl.
Figure 1 shows the elution curve of Te-121m and thetotal recovery ratio of Te-121m. The total recovery
ratio of Te-121m reached almost 100% with ﬁve bed
volume eluent, while antimony was adsorbed onto theanion exchange resin without elution.
In this research, we investigated the puriﬁcation of
tellurium from matrix antimony with pH regulation.
Its performance was satisfactory for a low antimony
concentration. Further investigations are required to
optimize the separation method for higher concentrations.
References

1) T. Kubota et al., RIKEN Accel. Prog. Rep. 50, 254(2017).
2) T. Kubota et al., RIKEN Accel. Prog. Rep. 52, 205(2019).
3) I. Puigdomenech, Chemical equilibrium diagrams:
MEDUSA, (2010), https://www.kth.se/che/medusa/
downloads-1.386254 (accessed 2020-07-20).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Chemical separation of theranostic radionuclide 111 Ag produced innat
Pd(d, x)111 Ag reactions
K. Ooe,∗1,∗2 T. Watabe,∗1,∗2 Y. Shirakami,∗2 D. Mori,∗3 T. Yokokita,∗3 Y. Komori,∗3 H. Haba,∗3 and
J. Hatazawa∗2,∗4

∗1
∗2
∗3
∗4

1 M HNO3 Conc. HNO3

50
Eluted radioactivity/%

Silver-111 (111 Ag, T1/2 = 7.45 d) is a candidate
radionuclide for theranostics (therapeutics + diagnosis). The nuclide emits β-particles (maximum β energy:
1036.8 keV), which can be applied to tumor therapy,and γ-rays with energies of 342 keV (branching ratio:7%) and 245 keV (branching ratio: 1.33%), which canbe used for imaging by single photon emission computed tomography (SPECT). However, 111 Ag has beenrarely applied in the ﬁeld of nuclear medicine. Toward
the nuclear medical use of 111 Ag, we previously measured the production cross sections of nat Pd(d, x)111 Ag
reactions.1) The energy at the peak of the excitation
function of the nat Pd(d, x)111 Ag reactions was approximately 9 MeV with a cross section of approximately
40 mb, which is consistent with the reported results.2–4)
In this study, 111 Ag was chemically separated froma metallic nat Pd target through anion-exchange chromatography for future nuclear medical application of
111
Ag.
111
Ag was produced by irradiating a stack of 6 metallic nat Pd foils (purity: 99.95%, thickness: 0.10 mm, Nilaco Corp., Japan) with a 24-MeV deuteron beam fromthe RIKEN K70 AVF Cyclotron. The average beam intensity was approximately 200 nA, and the irradiation
time was 30 min. After irradiation, one of the irradiated nat Pd targets was dissolved in a mixed HNO3
and HCl solution. After evaporation to dryness, theresidue was dissolved in 1 M HNO3 solution and thenfed into an anion exchange column (Muromac 1 × 8,
200–400 mesh, NO−
3 form, Φ10 mm × 11 cm). Firstly,111
Ag was eluted by 1 M HNO3 solution. According to
the literature,5) Ag shows no adsorption in 1 M HNO3
solution on an anion-exchange resin, while Pd adsorbs
on the resin. After the elution of 111 Ag, nat Pd was
stripped by concentrated HNO3 solution. Each eluted
fraction (approximately 1 mL) was subjected to γ-ray
spectrometry with a Ge detector for determining 111 Ag
radioactivity by using the 342-keV γ peak of 111 Ag. Because this γ peak was partly overlapped by the 345-keV
γ peak of 105 Ag (T1/2 = 41.29 d), which was simultaneously produced in the nat Pd(d, x) reactions, the area of
the 342-keV γ peak of 111 Ag was calculated by Gaussian ﬁtting. The elution behavior of nat Pd was checkedusing the 172-keV γ peak of 111m Pd (T1/2 = 5.5 h),which was also produced in the nat Pd(d, x) reactions.
Figure 1 shows the elution curves of 111 Ag and
Department of Nuclear Medicine and Tracer Kinetics, Osaka
University Graduate School of Medicine
Institute for Radiation Sciences, Osaka University
RIKEN Nishina Center
Research Center for Nuclear Physics, Osaka University- 196 -

Ag-111
Pd-111m

40
30
20
10
0

0

10
20
30
Elution volume/mL

40

Fig. 1. Elution curves of 111 Ag and 111m Pd in anionexchange chromatography.
111m

Pd obtained in this study. The elution of 111 Ag by
1 M HNO3 solution started from fraction #11 and almost ﬁnished at fraction #16 before the start of elutionof 111m Pd, showing the clear separation of 111 Ag fromthe nat Pd target. By changing the eluent to concentrated HNO3 after fraction #20, the elution of 111m Pdstarted from fraction #28. Very little 111 Ag and 111m Pd
radioactivities remained on the anion-exchange column
after completion of the separation. The recovery yieldsof 111 Ag and 111m Pd were approximately 99% and 98%,
respectively. This high yield for 111 Ag is quite suitable
for nuclear medical use, which requires large radioactivity for tumor therapy. Because many radioactive isotopes of Ag are produced in the nat Pd(d, x) reactions,the use of an enriched 110 Pd target is essential for theselective production of 111 Ag in the 110 Pd(d, 2n)111 Ag
reactions. However, enriched 110 Pd targets are quite
expensive, and it is important to recycle the 110 Pd target after the separation of 111 Ag. Therefore, the highrecovery yield for 111m Pd obtained in this study is alsofavorable for the separation of 111 Ag in medical use.
The present results will lead to preclinical studies oftherapeutic eﬀects with 111 Ag.
References
1) K. Ooe et al., RIKEN Accel. Prog. Rep. 52, 195 (2019).
2) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 217, 193 (2004).
3) N. Ukon et al., Nucl. Instrum. Methods Phys. Res. B
426, 13 (2018).
4) F. Ditrói et al., Nucl. Instrum. Methods Phys. Res. B
270, 61 (2012).
5) J. P. Faris, R. F. Buchanan, Anal. Chem. 36, 1157
(1964).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 53

Preliminary investigation of nanoclay-gel-based fluorescent gel
dosimeters under carbon-ion beam
T. Maeyama,∗1,∗2 A. Mochizuki,∗1,∗2 N. Fukunishi,∗2 and K. L. Ishikawa∗2,∗3
High-precision radiotherapy that focuses high doses ofradiation on tumors and decreases the amount of damage to healthy tissues is becoming popular. To validate
the complex dose distribution, tissue-equivalent dosimetry with high spatial resolution in three dimensions isrequired. Gel dosimetry has attracted attention for doseverification in advanced radiotherapy. A gel dosimeteris prepared from a radiation-sensitive compound and agelling agent. After a radiation-induced chemical reaction, the gel retains the same spatial distribution, andthe 3D dose distribution can be evaluated by 3D gel scanning. Gel dosimeters are categorized according to thecharacterization method used the nuclear magnetic resonance (NMR) measurement method,1–5) absorptiometry(X-ray6) or visible light7,8) ), and fluorometry. The sensitivity of detection by fluorometry9–11) is approximately
1,000 times greater than that by visible-light absorptiometry because fluorescence can be detected against
a low background, isolated from excitation light. In contrast, absorptiometry measures transmitted light relative
to high incident light levels at the same wavelength. The
measurement methods using NMR and X-ray computed
tomography (CT) also show limited detection sensitivity,
and the dose of irradiation products must be at least several Gy for successful detection. In contrast, mGy-level
dose can be detected by fluorometry. Thus, gel dosimeters employing fluorometry are expected to be the mosthighly sensitive type of gel dosimeter.
In a recent study, we reported a nanoclay-gel-based
dosimeter that uses fluorescent dyes for X-ray irradiation. Although most gel dosimeters are prepared usingorganic gelling agents, such as gelatin, sensitivity can beenhanced by introducing inorganic nanosized clay as thegelling agent.9–11) There are two types of such agents.
The first is nanoclay-based radio-fluorogenic gel (NCRFG), in which a fluorescent dye is produced when anon-fluorescent dye, such as coumarin-3-carboxylic acid
(CCA), reacts with radicals formed from the radiolysis
of water. The second type of gel is nanoclay-based radio degradation fluorescence gel (NC-RDG), in which
a non-fluorescent dye is produced when a fluorescentdye, such as rhodamine 6G (R6G) or 7-diethylamino-4methylcoumarin (7D4MC), reacts with radicals. In thisstudy, nanoclay-gel-based fluorescent gel dosimeters wereapplied to heavy-ion-beam irradiation for preliminary investigation.
Fluorescent gels were prepared using nanoclay as thegel, deionized water, and a fluorescence dye or probe.
Two types of gel dosimeters prepared for this study. One
was prepared from 2 µM 7D4MC and 2.5-wt% nanoclay
as follows. First, clay dispersion stock was prepared by
∗1
∗2
∗3

Kitasato Univ
RIKEN Nishina Center
Univ. of Tokyo

Fig. 1. Scanned image of fluorescent gel after irradiation with
135 MeV/nucleon 12 C6+ (entrance surface dose = 12 Gy).

mixing 23.35 g of ultra-pure water (Simplicity UV, Millipore Corp.) with 0.75 g of clay in a glass beaker atroom temperature. A fluorescence probe stock solution(500 mL) was prepared by mixing 1.14 mg of 7D4MC
with water. The clay dispersion stock (24.1 g) and fluorescence probe stock solution (5.9 mL) were then introduced to a 50 mL screw-capped glass vial and mixedusing a rotation/revolution vacuum mixer (V-mini300,
EME Corp., Japan) for 10 min at 1200/600 rpm and−90 hPa gauge pressure to obtain a uniform dispersion.
The other was prepared from 100 µM dihydrorhodamine 123 (DHR123) and 2.5-wt% nanoclay using arotation/revolution vacuum mixer with the same procedure. Finally, prepared gels were enclosed in a 100×100×
10 mm plate. The prepared samples were irradiated using 12 C6 -ion beams (135 MeV/nucleon) accelerated by
the RI Beam Factory (RIBF) at RIKEN. The irradiatedsamples were scanned using a fluorescent gel scanner.
The irradiation changes in fluorescence intensity with
irradiation were observed, as shown in Fig. 1. The left
image shows the entrance surface. In 7D4MC fluorescentgel, the fluorescence intensity decreases with increasing
dose, and in DHR123 fluorescent gel, the fluorescenceintensity increases with increasing dose. The detailed
results are currently being analyzed, and some results
will be submitted.
References

1) T. Maeyama et al., J. Radiat. Res. 57, 318 (2016).
2) T. Maeyama et al., J. Phys. Chem. B 121, 4238 (2017).
3) T. Maeyama et al., Radiat. Phys. Chem. 96, 92 (2014).
4) T. Maeyama et al., Radiat. Phys. Chem. 107, 7 (2015).
5) T. Maeyama et al., Radiat. Phys. Chem. 146, 121 (2018).
6) E. Maynard et al., Phys. Med. Biol. 63, 075014 (2018).
7) K. I. Penev et al., Med. Phys. 44, 1948 (2017).
8) I. Kawamura et al., Jpn. J. Appl. Phys. 58, 022003 (2019).
9) T. Maeyama et al., J. Phys. Conf. Ser. 1305, 012045 (2019).
10) T. Maeyama et al., Sens. Actuators A 298, 111435 (2019).
11) T. Maeyama et al., Radiat. Phys. Chem. 151, 42 (2018).

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4. Radiation Chemistry and Biology

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Mutants of the ectomycorrhizal mushroom Tricholoma matsutake thatexert detrimental eﬀects on its symbiotic partner Pinus densiflora †H. Murata,∗1 S. Nakano,∗1 T. Yamanaka,∗1 T. Abe,∗2 H. Ichida,∗2 Y. Hayashi,∗2 T. Shimokawa,∗1 K. Tahara,∗1
and A. Ohta∗3
Tricholoma matsutake is an ectomycorrhizal fungus
that produces the prized mushrooms “matsutake” insymbiotic association with conifers.1) In our attempts
to induce mutants of T. matsutake that could be useful in artiﬁcial cultivation for fruiting by γ-ray irradiation at 500 Gy, we isolated a mutant, designated as
G1, that grew better in substrates than the wild-type
NBRC 33136.1) The phenotype of G1 on agar plates
somewhat resembled that of Ar 59, which had been isolated by argon-ion-beam irradiation at 500 Gy; bothmutants overproduced amylase and cellulase activities
and exhibited a mycelial morphology diﬀerent from thewild-type, forming a fuzzy cotton-ball-like colony, rather
than a mycelial mat.1,2) In the present study, we examined how G1 and Ar 59 inﬂuence the plant growth ofPinus densiflora seedlings in vitro.
The inoculation was performed with two diﬀerent
methods. The ﬁrst involved sterile 1-week-old P. densiflora seedlings, in which the seedlings were planted
in a pumiceous soil substrate ﬁlled with T. matsutake
mycelia and axenically co-cultured at 23◦ C for 120 days.
The second involved sterile 1-month-old P. densiflora
seedlings already grown in the pumiceous soil, in which
T. matsutake mycelia were placed on the surface of thesubstrate where the shoot base emerged; they were axenically co-cultured at 23◦ C for 150 days.
In the ﬁrst experiment, G1 exhibited a signiﬁcantdetrimental eﬀect on both above- and below-ground organs; root systems were severely underdeveloped or collapsed, leading in turn to aboveground wilting (Fig. 1).

Fig. 1. Biomass measurements of 1-week-old P. densiflora
seedlings co-cultured with T. matsutake strains for 120
days.
†

∗1
∗2
∗3

Condensed from the article in Botany 97, 463–474 (2019)
Forest Research and Management Organization
RIKEN Nishina Center
Lake Biwa Environmental Research InstituteFig. 2. Biomass measurements of 1-month-old P. densiflora
seedlings co-cultured with T. matsutake strains for 150
days.

This result contrasts with the plant-growth-promoting
eﬀect of Ar 59, as well as NBRC 33136; the former allowed the seedlings to gain signiﬁcantly higher aboveground and total biomasses than the control, while thelatter allowed them to gain signiﬁcantly higher aboveground, belowground, and total biomasses (Fig. 1).
In the second experiment, seedlings associated with
G1 exhibited signiﬁcant decreases in their belowgroundbiomasses, and many lateral roots degenerated significantly, reducing their rhizosphere biomasses (Fig. 2).
Seedlings associated with Ar 59, in contrast, exhibited neither plant-growth-promoting nor plant-growthinhibiting eﬀects (Fig. 2). Unlike these mutants, NBRC
33136 promoted plant growth; the aboveground andtotal biomasses signiﬁcantly increased, but the belowground biomass did not (Fig. 2).
Data suggest that there could be a regulatory region in
the genome of T. matsutake that determines plant associating behaviors, depending upon where the mutations
occur and what environment the fungus inhabits basedon its endophytic association with non-host plants.3)
The overproduction of degrading enzymatic activities is
not the cause of G1’s trait of harming its symbiotic partner, because Ar 59 overproduced the same enzymatic
activities without harming P. densiflora seedlings. Genomic and transcriptomic analyses of these mutants willallow us to unearth the unknown regulatory mechanisms
involved in the ectomycorrhizal symbiosis of T. matsutake.
References

1) H. Murata et al., Botany 97, 463 (2019).
2) H. Murata et al., Mycorrhiza 28, 171 (2018).
3) H. Murata et al., Mycorrhiza 23, 235 (2013).
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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Eﬀect of heavy-ion-beam irradiation on mycelial growth of medicinal
mushrooms
M. Hatashita,∗1 K. Takagi,∗1 H. Ichida,∗2 and T. Abe∗2
It is well known that β-D-glucans from fungi areeﬀective initiators of cell-mediated immunity in humans.1) β-D-glucans isolated from various fungi diﬀer
in their chemical structures and, consequently, in theirimmunomodulatory activities. For example, schizophyllan, which is a β-D-glucan extracted from the fungus
Schizophyllum commune and is classiﬁed as a medicine,stimulates the immune system.2) We are aiming to establish beneﬁcial mutants from several extremely rare fungiwith immunostimulatory activities. We had alreadyachieved the isolation of several Cordyceps militaris mutants with higher proliferative activity by the repeatedpropagation of expanding hyphal tips from the protonbeam irradiation of the fungus.3) Heavy-ion beams havebeen accepted as an eﬀective mutagen.4) A small number of genes are expected to be disrupted in the mutant
genomes because heavy-ion beams can induce mutations
with a high frequency at relatively low doses. Such characteristics of heavy-ion irradiation are advantageous formutation breeding. In the latest study, prior to mutant screening by ion-beam breeding, we examined thedose dependence of mycelial growth of two fungi against
the irradiation of heavy-ion beams and compared themycelial-growth eﬀect of heavy-ion-beam irradiation tothat of proton-beam irradiation.
The microbial strain Fuscoporia obliqua NBRC 8681
was obtained from the National Institute of Technology and Evaluation. It was inoculated on an agar plate(potato dextrose agar [PDA5) ]) and incubated at 25◦ C.
The microbial strain Polyporus umbellatus ATCC 60546
was purchased from the American Type Culture Collection. It was inoculated on an agar plate (yeast malt
peptone agar [YM5) ]) and incubated at 25◦ C. Thesesamples were inoculated on fresh 6 cm plates 4 days
before the irradiation and incubated in the dark at
room temperature. The 200-MeV proton-beam irradiation (LET 0.5 keV/µm) on the culture plates was carried out by the Wakasa Wan Multi-purpose Accelerator
with Synchrotron and Tandem at the Wakasa Wan Energy Research Center in the dose range of 100–2,000 Gy.
The culture plates were irradiated with Ar ions (LET
180 keV/µm) and Fe ions (LET 640 keV/µm) in the dose
range of 100–300 Gy at the RIKEN RI-beam factory.
For the growth-rate measurement, three loops ofmycelia from the center of each irradiated plate were
inoculated on each center of three fresh 9 cm plates andincubated at 25◦ C. The maximum and minimum diameters of the mycelial zone of each plate were measured
using a vernier caliper 8 days later. The data from threeirradiated plates were averaged and compared with thedata from the control.
∗1∗2Res. and Develop. Dept., The Wakasa Wan Energy ResearchCenter
RIKEN Nishina Center

Table 1. Eﬀect of ion-beam irradiation on mycelial growthof medicinal mushrooms.

Table 1 lists the relative ratio of the mycelial growth
for two strains, which were irradiated with three kindsof ion beams, respectively. Under any irradiation condition, the mycelial growth rate decreased as the irradiation dose increased. For proton-beam irradiation, theresults for irradiation doses of 100 and 300 Gy were almost the same as those of the control (data not shown),
and the relative suppressions of mycelial growth were observed from 500 to 2,000 Gy. Relative ratios of mycelial
growth of 50.8% and 42.2% were obtained with F. obliqua after irradiation with 300 Gy of Ar and Fe ions,
respectively. Moreover, relative ratios of 5.3% and 2.3%
were obtained with P. umbellatus after irradiation with
300 Gy of Ar and Fe ions, respectively. Heavy-ion beams
showed a higher relative biological eﬀectiveness (RBE)of mycelial growth inhibition than proton beams, regardless of the kind of fungi.
References

1) D. L. Williams, Mediators Inﬂamm. 6, 247-50 (1997).
2) V. E. Ool, F. Liu, Liu, Curr. Med. Chem. 7, 715-29 (2000).

3) S. K. Das et al., Lett. Appl. Microbiol. 47, 534-8 (2008).
4) Y. Kazama et al., Genes Genet. Syst. 88, 189-97 (2013).
5) A. Imtiaj et al., Mycobiology 36, 34–39 (2008).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Yield improvement of starch-degrading enzyme in fungi by ion-beammutagenesis

Fig. 1. Survival curves of fungi producing starch-degrading
enzymes after C- and Fe-ion irradiation.
∗1∗2

Novozymes JapanRIKEN Nishina Center- 201 -

NTG

Relative activity (parent strain=1.0)

C-ion 400 Gy

Relative activity (parent strain=1.0)

Relative activity (parent strain=1.0)

To improve the productivity of amylolytic enzymes
in ﬁlamentous fungi that are widely used worldwide,
various breeding processes have been conducted so far.
In breeding by classical mutagenesis, chemical mutagen treatment, UV irradiation, and gamma-ray irradiation have been used for years on ﬁlamentous fungi;
however, the range of mutation could be narrowed withthe repeated use of the same conventional methods.
Therefore, this study was conducted with the aim of investigating the possibility of heavy-ion beams as a newsource of mutagenesis for breeding ﬁlamentous fungi.
The spores of Aspergillus niger that produce starchdegrading enzymes were dried on membrane ﬁlters(ADVANTEC, A020A025A), and these membranes,
packed in Hybri-bags (Cosmo Bio), were irradiatedwith heavy-ion beams of carbon and iron (50 to
400 Gy). The LETs of C and Fe ions were 76 keV/µm
and 640 keV/µm, respectively.
The mutants obtained from 200 Gy of C ions and
400 Gy of Fe ions with a survival rate of approximately 20% were examined for their enzyme productivity (Fig. 1).
Simultaneously, we also examined mutants that
had been treated with N-methyl-N′ -nitro-N-nitrosoguanidine (NTG) and UV irradiation on the same A.
niger strain and compared them with those obtainedusing heavy-ion beams.
Among the mutagens used, NTG treatment yielded
the most diversiﬁed morphology on the strain, andUV irradiation showed the least change in morphology. The morphology of mutants treated with heavy-

Relative activity (parent strain=1.0)

H. Iwahara,∗1 T. Matsui,∗1 H. Ichida,∗2 and T. Abe∗2

Fe-ion 200 Gy

UVFig. 2. Yield deviations of mutants treated with various
mutagens.

ion beams was less diversiﬁed than that of NTG, but
considerable diversity was still observed in the sporulation and the length of aerial hyphae.
In addition, 920 strains were randomly isolated fromeach mutagen group and cultivated in a liquid medium
with 96-well microtiter plates, and their enzyme productivity was examined and compared with that of theparent strain (Fig. 2). The NTG mutant group showed
the largest variation, but both the C-ion and Fe-ion
mutants also showed a wide variation. In addition,
several mutants from both the ion beams and NTG
showed a higher productivity than the parent strain.
These mutants will be further examined in larger-scale
fermentation.
From these results, it was conﬁrmed that the heavyion beam was eﬀective against A. niger as a mutagenesis tool for improving productivity. We will continue
to conduct screening on a larger scale with the aim offurther improving enzyme productivity.

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Mutation breeding of sake yeast using heavy-ion-beam irradiation

In recent years, the total sake consumption has been
decreasing, although the consumption of fruity sake variants such as Ginjo-shu is increasing. Taste of fruity
sake results from malic acid.1) Malic acid is produced byyeast during main fermentation (moromi).2) The main
objective of this study is to isolate a high-malic-acidproducing yeast strain through the irradiation of heavyion beams to develop high-value-added products.
The parent strain is an in-house yeast strain, T-66. It
is isolated from Kyokai-kobo K-6 and tends to produce
more organic acid more than K-6. T-66 was precultured
in 5 mL of a koji extract medium (a Baumé degree of6.0) at 30◦ C for 2 days. The cultured yeast cells werespread on YPD agar medium plates [20 g/L (w/v) glucose, 20 g/L (w/v) polypeptone, 10 g/L (w/v) yeast
extract, and 18 g/L (w/v) agar]. We irradiated theplates with 500 Gy of Fe-ion beams (790 keV/µm) at
the RIKEN Nishina center in Jury 2018. After incubation at 30◦ C for 5 days, 88 mutant yeast strains wereisolated from the plates.
As primary screening, the mutagenized yeast strains
was precultured in 5 mL of koji extract medium. 3 mL ofyeast culture was added to 20 mL of koji extract medium
supplemented with 7 g alcohol-dehydrated koji and incubated at 20◦ C for 10 days.3) Filtrated mediums were
measured using an alcohol densitometer (Alcomate AL2, Woodson Riken Keiki, Tokyo), and titratable acidTable 1. Analysis of mutant yeast strains.

Alcohol
content [%]
19.7
19.5
18.9
18.2
16.6
20.2
20.0
19.7
20.1

Sample name
Parent strain
P1-8
P2-11
P3-10
P4-3
P6-12
P6-9
P7-13
P7-6

Titratable
acidity [-]
4.5
5.2
4.8
4.9
4.8
4.9
4.8
5.0
4.8

Malic acid
[mg/L]
639.2
908.3
624.8
975.6
797.8
778.5
725.7
884.3
1100.5

Table 2. Analysis of small-scale sake brewing.
Samplename

Parentstrain
P1-8
P3-10
P7-6
∗1
∗2

Sake
meter
value [-]

Alcohol
content[%]

Titratable
acidity
[-]

Amino
acid
content [-]Sensory
evaluation

+4.6

17.1

2.9

0.8

3

+4.1
+1.8
+9.1

16.8
16.6
17.3

3.6
3.6
3.4

0.8
0.8
0.7

2
1
2

Akita Shurui Seizoh Co., Ltd.
RIKEN Nishina Center

Organic-acidamount [mg/L]

K. Baisho,∗1 H. Tomioka,∗1 Y. Furuki,∗1 Y. Hayashi,∗2 and T. Abe∗2
2,000
1,500
1,000
500
0

Acetic acid
Malic acid
Citric acidL-lactic acid

Parentstrain

P1-8

P3-10

P7-6

D-lactic acid

Fig. 1. Organic-acid production of isolated mutant yeast
strains.

ity was measured using the oﬃcial analysis method of
the National Tax Agency. We selected 8 mutant yeast
strains that produced more organic acids than the parent strain without producing any oﬀ-ﬂavor. Next, theamount of organic acid (succinic acid, lactic acid, citricacid, malic acid, and acetic acid) was measured using
an F-kit (J. K. International, Tokyo). Table 1 lists theresults of primary screening. The malic-acid production
amounts of P1-8, P3-10, and P7-6 strains were higher
than those of the parent strains.
As secondary screening, the parent strain, T-66, and 3
selected mutant yeast strains were examined by smallscale sake brewing. After the ﬁltration of fermentation mash, the sake meter value (SMV), an indicatorof sweetness of sake; alcohol content; titratable acidity;
and amino-acid content were measured using the oﬃcial
analysis method of the National Tax Agency. Additionally, we performed sensory evaluation (3-step rating: 1
is good and 3 is bad). Table 2 lists the results. The
three selected mutant yeast strains produced more organic acid than the parent strain. While the SMVs are
diﬀerent, the three mutants show almost the same levelof alcohol production as T-66. This result shows that thethree mutant yeasts have good brewing ability. P3-10
scored the highest value in sensory evaluation. To verify
the reason for this result, the amount of organic acid wasmeasured using an F-kit (Fig. 1). P3-10 showed a higher
malic-acid content and lower succinic-acid content thanthe other mutants, indicating that the sake brewed withthis strain will have a light taste that matches the preference of recent consumers. It was shown that the P3-10
strain produces a lighter-tasting sake than the parent
strain, T-66.
We isolated the high-malic-acid-producing yeast strain
P3-10 derived from T-66. P3-10 produces not only more
malic acid but also more acetic acid more than T-66.
Because acetic acid produces an oﬀ-ﬂavor for sake, weplan to improve on the P3-10 strain.
References

1) Y. Shimazu et al., J. Brew. Soc. Japan 106, 747 (2011).
2) M. Toyozawa et al., J. Ferment. Technol. 38, 342 (1960).
3) K. Saito et al., J. Brew. Soc. Japan 87, 915 (1992).
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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Isolation of morphological mutants in a bryophyte model
Marchantia polymorpha using heavy-ion mutagenesis
S. Sakai,∗1 C. Hirata,∗1 Y. Sakai,∗1 Y. Kazama,∗2,∗3 T. Abe,∗2 and K. Ishizaki∗1
Since land plants emerged approximately 470 million
years ago, their body plans have changed signiﬁcantly
during evolution through a transition from gametophytedominant to sporophyte-dominant life histories and thedevelopment of many specialized tissues and organs,such as stomata, vascular tissues, roots, leaves, seeds,
and ﬂowers. Bryophytes occupy a basal position inland-plant evolution, and the haploid (n) gametophyte
is dominant over the diploid (2n) sporophyte in theirlife histories, while angiosperms (ﬂowering plants), thelast diverged group of land plants, have diploid (2n)sporophyte-dominant life histories. For better understanding of the evolution of body plan in land plants,
the accumulation of knowledge about the molecularmechanism for the gametophytic organ development inbryophytes is needed. Forward-genetic approaches focusing on the gametophyte development in bryophytes
are especially important.
The bryophyte Marchantia polymorpha is a classical but recently emerging model plant. Recently, powerful experimental tools for molecular genetics havebeen established in M. polymorpha, including highfrequency transformation techniques and genome-editing
techniques using the CRISPR/Cas9 system,1) in addition to the whole genome sequence information.2)
As it exhibits low genetic redundancy in most regulatory pathways,2) M. polymorpha should be advantageous for forward-genetic approaches. Similar to otherbryophytes, the spores are haploid; therefore, the eﬀectof the induced mutations can be immediately observedin the ﬁrst gametophyte generation developed from thespores.
In this study, we adopted a heavy-ion beam as themutagen for screening mutants with altered gametophyte
morphology in M. polymorpha. Spores, which are single

Fig. 2. Wild-type thallus (A) and isolated morphological mutants (B) of M. polymorpha.

Fig. 1. Assessment of the mutagenicity of carbon-ion beams
on the spores of M. polymorpha. Plants grown from thespores irradiated with carbon-ion beams were observed(A), and the ratio of normal thallus development wasevaluated (B) (N = 4, n = 69–466, bar = SD). Values
accompanied by diﬀerent letters are signiﬁcantly diﬀerent(Tukey’s test, p < 0.05). Arrow, growth-arrested plants.

cells and the start point of the development of the thallus(plant body) in M. polymorpha, were irradiated with acarbon-ion beam (LET: 30 keV/µm) at a dose of 100 Gy
or 150 Gy. Carbon-ion irradiation decreased the ratioof the normal thallus development from the spores in aradiation-dose-dependent manner (Fig. 1A and B).
Subsequently, the plants developed from spores irradiated with carbon-ion beams were further cultured forseveral weeks to screen for mutants. To date, 19 mutants
showing abnormal thallus development were successfully
isolated among ∼9,000 individuals. As shown in Fig. 2A,
on the thallus surface of the wild-type plant, air chambers (yellow square) and gemma cups with clonal progenies, gemmae (blue square), are developed. Two of the 19
isolated mutants develop defective air chambers, 10 haveabnormal gemmae and gemma cups, and 7 showed defects in both air-chamber and gemma-cup development.
For example, a mutant ss12 shows a marked decreasein the frequency of air-chamber formation and ch2 hasgemma cups with no gemma (red square), while ss656,
ss691, and ss793 are deﬁcient in the development ofgemma cups (Fig. 2B). We are currently conducting thedetailed characterization of morphological phenotypes inthese mutants, in parallel with the identiﬁcation of thecausal genes using next-generation sequencing (NGS).
These mutants seem promising to reveal important factors functioning in the gametophytic organ developmentin the model basal land plant M. polymorpha.

∗1

References∗2∗3

Dep. Biol., Fac. Sci., Grad. Sch. Sci. Kobe Univ.
RIKEN Nishina Center
Fac. Biosci. Biotech., Fukui Pref. Univ.

1) K. Ishizaki et al., Plant Cell Physiol. 57, 262–270 (2016).
2) J. L. Bowman et al., Cell. 171, 287–305 (2017).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Breeding of summer-autumn-flowering small-flowered spray-type
chrysanthemums cultivar ‘Nagasaki SWC1’ by heavy-ion-beamirradiation
A. Hisamura,∗1 J. Morooka,∗2 T. Abe,∗3 Y. Hayashi,∗3 and T. Hirano∗3,∗4
In Nagasaki Prefecture, the small-ﬂowered spray-type
chrysanthemums is promoted for planting in open ﬁelds
because producers can cultivate it at low cost. It has agreat demand during Obon (early in August) as a funeral ﬂower in Japan. It is necessary to ship three colors of ﬂowers (red, white, and yellow) simultaneously
from the market. However, the shipment time is unstable because of bloom delays or bud departing at theearly stage caused by high temperatures during the cultivation period. Therefore, the development of a new
cultivar that enables a stable shipment time has been
desired to meet the needs of the market. We conductedcross-breeding and selected a superior red lineage forwhich the blooming time can be controlled using longday treatment under lighting (Fig. 2(a)). In this study,
we irradiated this superior red lineage with a heavy-ion
beam to obtain cultivars of diﬀerent colors that have thesame shipment time as the superior red lineage. It has
been reported that the ﬂower color of the original cultivar is important to obtain a wide mutation spectrumof the ﬂower color in Chrysanthemum.1) This cultivar
was thought to be suitable for inducing mutations of
the ﬂower color such as white or yellow. As a result,
we succeeded in developing a new cultivar known as“Nagasaki SWC1” with white ﬂowers in 2018.
We irradiated 27 scions of the superiod red lineage
with C-ion beams (LET: 23 keV/µm) at a dose of 5 Gy
at RIKEN Nishina Center in January 2015. We planted
and pinched the irradiated scions as a mother stock, following which we picked scions. We planted these scions
in the ﬁeld and obtained 984 candidate mutant plants,
including 49 ﬂower-color mutants. Some of these mutants were chimera. Therefore we isolated the plants
with only white ﬂowers in the ﬁrst selection. We multiplied these plants and cultivated them in the ﬁeld in
2016. Subsequently we selected a superior plant named“W1-1” in the second selection. The third selection was
performed in 2017 to conﬁrm its stability of characteristics and ﬂower color. The ﬁnal experimental productionof “W1-1” was performed at the ﬁeld of an agricultural
center, and “W1-1” gained high evaluation in a test ofadaptability to local ﬁelds in 2018. We named this superior cultivar “Nagasaki SWC1” and applied for theregistration of this variety on March 18, 2019.
“Nagasaki SWC1” has a white (white-group 155-C
on the R.H.S. color chart) single ﬂower (Fig. 2(b)). It
∗1
∗2
∗3
∗4

Agriculture and Forestry Technical Development Center, Nagasaki Prefectural Government
Shimabara Development Bureau
RIKEN Nishina Center
Faculty of Agriculture, University of Miyazaki

Fig. 1. Original flower and the flower-color mutants.

Fig. 2. Original flower (a) and a new cultivar “Nagasaki
SWC1” (b).

blooms in the middle of July under natural long days.
It is also possible to control blooming by long-day treatment under light culture and adjust the shipment timeto the period of highest demand which is early August. Furthermore, “Nagasaki SWC1” has a small unnecessary inferior branch. This characteristic provides
a labor-saving plant shape which is suitable for bouquet
making. These characteristics of “Nagasaki SWC1” areinherited from the superior red lineage. Therefore, red
and white ﬂowers can be shipped simultaneously in the
period of highest demand. This is a great advantage for
producers, and an increase in their income can be expected. Presently, we are working on breeding a yellow
ﬂower line. Our aim is to breed a new cultivar for a setof three colors of small-ﬂowered spray-type chrysanthemums.
Reference
1) K. Tamaki et al., Hort. Res. (Japan) 16, 117 (2017).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Mutation induction in strawberry of original Saitama cultivar by C-ion
irradiation
H. Uchida,∗1 H. Oda,∗1 E. Kondo,∗1 Y. Hayashi,∗2 and T. Abe∗2
Agriculture in Saitama prefecture is in a poor situation owing to the aging of producers and the decreasein the number of new farmers. Strawberry is one of theimportant farm products of Saitama because of its highproductivity per unit area. We have been working on
the breeding of strawberry since 2008 to enhance theproduction of strawberry. We successfully produced ouroriginal cultivars “Saien I-1Go” and “Saien I-3Go” 1) andregistered them in February 2019. These cultivars havea rich taste with high sugar content and moderate acidity, as well as a good balance between sweetness andacidity. Therefore, the production of these cultivars is
expected to expand in the near future. On the other
hand, they have the disadvantaged of a late harvest period and low yield compared to general main varieties.
In addition, the peel color of “Saien I-3Go” darkens in
the warm season, which results in a reduced evaluationof the fruit appearance. To solve these problems, we
conducted mutation breeding by using heavy-ion beams
and are in the process of developing promising lines withimproved yield factors such as an increased number offruit sets, an earlier harvesting season, and a desirable
peel color.
We used “Saien I-1Go” and “Saien I-3Go” for irradiation from 2015 to 2018. The seedlings were irradiatedwith C-ion beams (LET 22.5 keV/µm) at dose ranges of
10–30 Gy, 30–80 Gy, and 30–120 Gy in 2015–2016, 2017,and 2018, respectively. After irradiation, seedlings weregrown by cuttings. The survival rate was measured after
4 to 5 weeks, and the growth and changes in peel color
were observed after planting. Selected mutant lines were
propagated in a runner plant, and the stability of mutant
Table 1. Survival rate of “Saien I-1Go” and “Saien I-3Go.”

Dose

Survival rate (%)(Gy)

Saien I-1Go

Saien I-3Go

0

100.0

100.0

30

90.7

93.2

40

92.8

-

60

78.3

61.9

80

60.0

-

90

-

26.4

120
4.4
"Saien I-1Go" in 2017, and "Saien I-3Go" in 2018 
The number of surviving plants was counted 4 ("Saien,*R RU 6DLHQ,*R ZHHNVDIWHULUUDGLDWLRQ
∗1∗2

Saitama Agricultural Technology Research Center
RIKEN Nishina Center

0XWDQW&RQWURO

Fig. 1. Peel color of a mutant of “Saien I-3Go” irradiated at
a dose of 30 Gy.

&RQWURO

0XWDQW

Fig. 2. High-branching mutant of “Saien I-1Go” irradiated at
a dose of 80 Gy.

traits was confirmed in the next year.
According to the result, both “Saien I-1Go” and “Saien
I-3Go” survived even at a dose of 80 Gy or more. A previous study showed that the lethal dose 50 of C-ion irradiation for apple and Japanese pear scions are 18 Gy and
13 Gy, respectively.2) This suggests that the seedlings ofstrawberry may be a viable plant species even at highirradiation doses relative to those of other plants of thefamily Rosaceae (Table 1).
We obtained several mutant lines in this study. One ofthese mutant lines changed the peel color from dark red
to light red (Fig. 1). Another line increased the number of branches and flowers owing to abnormal branching morphology (Fig. 2). We are currently investigating
the other characteristics of these promising mutant lines,
such as the grass shape, flowering time, and yield. We
are also investigating whether the target trait is inherited in progeny and examining whether it is promising
as a breeding stock.
The peel color of the mutant is lighter than that of thecontrol.
The number of branches and flowers increased in the
mutant.
References

1) H. Oda et al., Bulletin of the Saitama Agricultural Technology Research Center. jpn. 17, 7 (2018).
2) Y. Ito et al., RIKEN Accel. Prog. Rep. 37, 151 (2004).
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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Characteristics of heavy-ion mutagenesis in cultivated strawberry
T. Wada,∗1 T. Sueyoshi,∗1 K. Oku,∗1 K. Shimomura,∗1 and T. Abe∗2
A cultivated strawberry cultivar “Fukuoka S6” hasbeen a popular product in the Japanese strawberry market due to its high quality, which is attributed to desirable characteristics, such as large, deeply red, glossy andtasty fruits. However, this cultivar also has some disadvantages, such as late maturity and a soft fruit pericarp,
which causes physical damage to the fruit while transporting. Ion-beam irradiation has attracted much attention as a novel technique for inducing spotted mutagenesis on plant genomes.1) This study developed mutantsof strawberry, which show early ﬂowering and high fruit
ﬁrmness, by using heavy-ion-beam irradiation.
An experiment was performed in 2014 and 2015. In
2014, strawberry nursery seedlings (5 plants per treatment) propagated in a sterilized condition were exposed
to a 12 C6+ ion-beam (1.62 GeV, LET 30 keVµm-1) at the
RIKEN Ring Cyclotron at doses of 0 (no treatment), 10,
15, 20, or 30 Gy. In 2015, seedlings were propagated similarly, separated, and ﬁlled up in a 50-ml falcon tube (at7 g per tube). Eight tubes per treatment were exposed
to a 12 C6+ ion-beam. Irradiated seedlings were transplanted and cultured on 1/2MS media at 20◦ C with a
16-h light regime, the weight of seedlings after 2 months
from transplanting were measured, and the propagation ratio was calculated in comparison with the initial
weight. The eﬀect of each treatment was evaluated bycomparing the propagation ratio to that achieved without treatment. Surviving seedlings were potted, acclimated, and transplanted in a greenhouse. The characteristics of mutants were examined using “Fukuoka S6”
as a control.
The propagation ratio decreased with an increase in irradiation dose, but the propagation ratio at 30 Gy, which
was the highest dosage, was 74% of that achieved without treatment (Fig. 1). Although many previous studies
using cultivated strawberry adopted a dosage of approximately 10 Gy, such as 8 to 16 Gy,2) 10 to 20 Gy,3) and
0.5 to 2.5 Gy,4) to obtain mutants in a practical breeding

Table 1. Characteristics of strawberry seedlings mutated bycarbon-ion-beam irradiation.
Trait
Fruit color
Fruit size

∗1
∗2

Fukuoka Agric. Res. Cent.
RIKEN Nishina Center

Total
7
5
0
61

Fig. 2. Fruits of a mutant line developed from 15 Gy heavyion-beam irradiation (left) and “Fukuoka S6” (right).
Bars = 1 cm.

program, the median lethal dose (LD50 ) has not been
detected. The survival ratio at 32 Gy of 12 C6+ ionbeam irradiation was 91%,2) suggesting that the LD50
of strawberry is greater than 30 Gy. Since the genome ofstrawberry was allo-octoploid (2n = 8x = 56), genes ona homoeologous genome might have compensated for theloss of functions of a certain gene. Summarizing thoseprevious studies and this study, the practical and suitable dosage of 12 C6+ heavy-ion-beam irradiation to obtain mutants of cultivated strawberry eﬃciently should
be further investigated.
Some surviving plants indicated characteristics different from “Fukuoka S6” in the forcing culture of thegreenhouse (Table 1). The fruit-pericarp pigmentationof mutants varied widely from darker red to lighter red(Fig. 2), but the fruit size only showed downsizing; further, some mutants showed harder fruit ﬁrmness thanthe control.
References

Fig. 1. Propagation ratio of strawberry seedlings mutated bycarbon-ion beam irradiation.

Darkening
Lightening
Upsizing
Downsizing

Absorbed dose (Gy)
10 15 20
30
1
2
1
3
1
4
0
0
0
0
0
0
12 23 10151) A. Tanaka et al., Genes Genet. Syst. 72, 141 (1997).
2) N. Chiba et al., JAEA-Review 2008-055, 78 (2008).
3) T. Abe et al., Breed. Res. 16, 67 (2014).
4) M. Yotoriyama et al., JAEA-Review 2010-065, 71(2011).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Improvement of the Brix content of the sweet potato “Anno-Beni”
by mutation induced using heavy-ion-beam irradiation
T. Hashiguchi,∗1 K. Yamane,∗1 J. Nagai,∗1 F. Tojima,∗1 K. Ishii,∗2 Y. Hayashi,∗2 and T. Abe∗2
Table 1. Line selection by dry-matter ratio of mutants ofthe sweet potato “Anno-Beni” obtained by C-ion-beamirradiation.

Dose(Gy)

Number ofregenerated
shootsNumber of
selected
plants

5

107

25

10

70

5

15

19

1

Table 2. Dry matter and Brix content of 4 mutant lines ofsweet potato.

Line name

Dose
(Gy)

Testedroot
tubersMean ofdry
matterratio (%)

Mean of
brix
(%)

No.15
No.17
No.27
No.34
Control(B1)

5
5
5
10
-

7
7
5
5
16

34.3
34.1
35.9
36.0
33.3

12.4
12.7
13.0
13.2
11.6

15

Steamed sweet potato Brix (%)

Heavy-ion-beam irradiation eﬀectively induces plantmutations and is used for plant breeding.1) The sweet
potato cultivar “Anno-Beni,” which has a high sugar
content, is an important and special product in the
Tanegashima island area. However, the weather cancause the sugar content to be unstable and the productto taste bad. Sugar is produced from starch by storage and heat, and it turns into sweetness. However, thedry-matter content and starch content change according to the harvest time, storage period, and tuber root
position. Therefore, by inducing mutations throughheavy-ion-beam irradiation, varieties and strains witha stable sugar content have been selected. In thisstudy, we measured the dry-matter contents of selectedmutants irradiated with a heavy-ion-beam, and in thisreport, we describe the eﬀect of the irradiation on thesugar content.
Embryogenic callus derived from the stem apex of
the “Anno-Beni” B1 line were irradiated with a C-ionbeam (LET 23 keV/µm) at a dose of 5, 10, and 15 Gy
in 2015. Regenerated plants that grew normally wereobtained from the irradiated callus. Subsequently, we
propagated 196 individual plantlets to 5 clone plants,
respectively, and cultivated them in the ﬁeld of KIAD
∗ 1, Kumage Branch for line selection in 2016. We
selected 31 lines that grew better and had higher drymatter contents than the control (Table 1).
In the next year, the 31 selected lines were grownby vegetative propagation, and 5 individual plants perline were cultivated in the ﬁeld. We investigated theplant growth and dry-matter contents in 2017. The
root tubers of the 4 lines were steamed and, diluted
with water in a 1 : 1 ratio, their Brix contents were
measured. Brix is the sugar content of an aqueous solution. It is known that there is a correlation between
the dry-matter rate and Brix percentage of tuberous
roots in sweet potato.2) Although the means of the drymatter content in 4 mutant lines showed no signiﬁcantdiﬀerence, the Brix contents of 4 lines were higher thanthose of the control (Table 2).
Some root tubers produced by mutant lines had
a higher Brix percentage and dry-matter rate thanthe control (Fig. 1). These results, obtained throughthe individual selection of mutant lines showing better
growth and higher dry-matter contents than the control, suggest that high-Brix-content strains could beselected.

14
13
12
Control

11

C5Gy No.15 n=7
C5Gy No.17 n=7

10
9

n=16

C5Gy No.27 n=5
C10Gy No.34 n=5

25

30
35
Dry matter content (%)

40

Fig. 1. Correlation between Brix content and dry-matterratio in root tubers produced by 4 mutant lines.

References∗1∗2

Kagoshima Prefectural Institute for Agricultural Development (KIAD)
RIKEN Nishina Center- 207 -

1) T. Abe et al., Breed. Res. 16, 67 (2014).
2) M. Ouchida, K. Ueno, Rep. Kyushu Br. Crop Sci. Soc.
Japan 80, 22 (2014).

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Development of mutagenesis technique for leguminous crops using
heavy-ion-beam irradiation and screening of useful mutants
P. Siviengkhek,∗1 K. Ishii,∗2 T. Sato,∗2,∗3 Y. Hayashi,∗2 and T. Abe∗2
Leguminous crops (soybean, mungbean, and peanut)
are important sources of lipid and protein for the humandiet. In Lao PDR, mungbean and soybean productions
are well suited to local soil and temperature conditions,which include both wet and dry seasons. However, soybean and mungbean productions are currently operated
on a small scale and at a household level depending on
the local farmers’ skill. There are several factors hampering the expansion of the production area and yieldfor both crops. Mungbean has an indeterminate ﬂowering habit, which implies that it does not have a deﬁned
ﬂowering period and will continue ﬂowering as long as
adequate soil moisture is provided. Consequently, harvesting mungbean is costly because of its long cultivation period and loss of grains from early-matured pods.
On the other hand, most varieties of soybean are sensitive to the photoperiod. It is necessary to cultivate
suitable varieties depending on the locations or seasons;otherwise, some varieties ﬂower early, resulting in a low
production yield. To overcome these diﬃculties, productions of mungbean with a determinate ﬂowering trait
and soybean with a non/less photosensitive trait are desired. Some mutants of soybean have been obtained withcarbon-ion-beam irradiation.1–3) In this study, to determine an eﬃcient condition for mutant induction, we irradiated mungbean and soybean with heavy-ion beams atvarious absorbed doses and observed the eﬀects on plant
growth.
Dry seeds of mungbean (Vigna radiate ‘Pakse’) andTable 1. Germination and growth of soybean (ARC3) irradiated by C-ion and Ar-ion beams at diﬀerent doses.
Ion
Control
C

Dose
(Gy)

Germination
rate
(%)

Survival
rate
(%) *

0
90.0
90.0
25
63.3
63.3
50
70.0
70.0
75
70.0
56.7
100
80.0
63.3
125
80.0
23.3
150
80.0
43.3
200
80.0
16.7
Ar
5
83.3
83.3
10
90.0
83.3
20
90.0
76.7
30
63.3
26.7
* Number of growing plants / 30 sown seeds** Plant height /average height of control plants
∗1
∗2
∗3

GrowthIndex **
1.00
0.99
0.91
0.82
0.73
0,50
0.68
0.26
0.88
0.80
0.65
0.39

Maize and Cash Crop Research Center, National Agriculture,
Forestry and Rural Development Research Institute (NAFRI)
RIKEN Nishina Center
Graduate School of Agriculture, Tohoku University

Table 2. Germination and growth of mungbean (Pakse) irradiated by C-ion and Ar-ion beams at diﬀerent doses.
Ion
Control
C

Ar

Dose
(Gy)
0
25
50
75
100
125
150
5
10
20
30
40
50

Germination
rate
(%)
100.0
96.7
93.3
80.0
96.7
96.7
96.7
86.7
90.0
86.7
90.0
83.3
63.3

Survival
rate
(%) *
83.3
80.0
83.3
80.0
86.7
93.3
70.0
83.3
70.0
73.3
90.0
83.3
63.3

GrowthIndex **
1.00
0.93
0.98
0.95
0.97
0.83
0.86
1.00
0.92
0.91
0.92
0.66
0.54

soybean (Glycine max L. Merr ‘ARC3’) are packed intoa rectangular plastic box or into a plastic petri dishin which a cork sheet is bedded to lay seeds in a single layer. Seeds of mungbean and soybean packed into
the rectangular plastic box were irradiated with C ions(135 MeV/n) at doses of 0–150 Gy and 0–200 Gy, respectively. The LET of C-ion beams was controlled to
30 keV/µm. Seeds packed into the plastic petri dish were
irradiated with Ar ions (160 MeV/n) at doses of 0–50 Gy.
The LET of C-ion beams was controlled to 188 keV/µm.
After irradiation, the seeds were sowed at an experimental ﬁeld.
Soybean showed sensitivity to both C-ion (in the range
of 0–200 Gy) and Ar-ion (0–50 Gy) beams (Table 1). Although mungbean showed lower sensitivity, the growthrate was reduced to 0.83 after 125 Gy irradiation of a Cion beam and to 0.54 after 50 Gy irradiation of an Ar-ion
beam (Table 2). To optimize the mutation rate, we determined the minimal doses that yield a growth index appropriate for mutagenesis with heavy-ion beams. Therefore, we determined the appropriate absorbed doses formutant selection as follows: for soybean, C-ion beams at
75 and 100 Gy, and Ar-ion beams at 10 and 20 Gy wereused; for mungbean, C-ion beams at 125 and 150 Gy, andAr-ion beams at 30 and 40 Gy were used. Among theirradiated soybean plants, some male sterile plants were
found. The highest percentage of male sterile plants was
67% after Ar-ion-beam irradiation at 20 Gy, followed by
33%, 17%, and 17% after C-ion-beam irradiation at 150,
125 and 100 Gy, respectively. On the other hand, there
were no male sterile plants among mungbean plants.
References

1) H. Kuribara et al., RIKEN Accel. Prog. Rep. 43, 286 (2010).
2) S. Arase et al., Plant Biotech. 28, 323 (2011).
3) R. Grasso et al., PLoS One 11, e0167998 (2016).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Mutants of sorghum variety “WRAY” induced by heavy-ion
irradiation
H. Cai,∗1 N. Yuyama,∗1 and T. Abe∗2
Sorghum [Sorghum bicolor (L.) Moench; 2n = 2x =20] is one of the most important cereals for food, forage, sugar, and biofuel worldwide.1) Sorghum, maize(Zea mays), rice (Oryza sativa), wheat (Triticum aestivum), and barley (Hordeum vulgare) are called theworld’s five major food crops, and sorghum is thestaple for more than 500 million people worldwide(http://www.fao.org). In this study, to induce mutations, dry seeds of sweet sorghum variety “WRAY”
were treated using Ar- and C-ion beams in RIBF from2015 to 2016.
The seeds were irradiated with Ar (290 keV/µm)ions and C (30 keV/µm) ions. The doses of the Ar
and C ions were 5 to 50 Gy, and 50 to 125 Gy, respectively. Survival rates were estimated by counting
M1 plants surviving in the field. M2 seeds were harvested separately from each self-pollinated M1 plant.
The mutants were identified from M2 plants. Mutation rates were calculated based on the numbers of M1lines, which showed morphological mutants in M2 generation. The highest rate of morphological mutants
was observed at a C-ion irradiation dose of 75 Gy (Table 1). A total of 9 morphological mutants were identified from 374 lines, among which, 2 mutants were in
Ar- treated plants and 7 mutants were in C- treatedplants. The phenotypes of mutants were dwarf, yellow
leaf, late heading and early heading (Fig. 1). Ma3 is
an important flowering-time gene that will be useful insorghum breeding.2) A next-generation sequencing andgenetic analysis revealed that an early-heading mutant
has a 1-bp deletion in Ma3. The genetic analysis ofother mutants is ongoing.
Table 1.

Ions

Dose (Gy)Survival
rate (%)

Control
Ar

0
5
10
15
50
75
100

80
83
48
18
91
67
21

125

15

C

∗1
∗2

a

b

c

d

Fig. 1. Mutations induced by heavy-ion beams. (a) Early
line, (b) dwarf line, (c) late line (left) and wild type(right) and (d) yellow leaf line (left) and semi-dwarf
line.

References
1) A. H. Paterson et al., Nature 457, 551 (2009).
2) K. L. Childs et al., Plant Physiol. 113, 611 (1997).

Eﬀects of ion-beam irradiation on mutation induction.

No. of M1
lines

No. of morphological mutants
yellow leaf

85
49
5

1

235

1

dwarf

late
headingearlyheading1113Forage Crop Research Institute, JGAFSA
RIKEN Nishina Center- 209 -

Total

2

1

Mutationrate (%)

0

1.2
2.0
0

7

3.0

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Genetic analysis of an early flowering rice mutant induced
by argon ions
R. Morita,∗1 H. Ichida,∗1 K. Ichinose,∗1 Y. Shirakawa,∗1 Y. Hayashi,∗1 T. Sato,∗1,∗2 and T. Abe∗1
Heading date, also known as ﬂowering time, is one of
the important traits for a crop such as rice to achievea high yield by making eﬀective use of sunlight andtemperature.1) Although numerous genes inﬂuencing
the heading date have been identiﬁed and characterized in rice, it is necessary to identify novel genes that
determine the heading date to understand the mechanism to control this trait. To identify a novel geneinﬂuencing the heading date, we isolated a rice mutant(Ar-G150) that exhibited an early ﬂowering phenotype
from a rice (Oryza sativa L. cv. Nipponbare) M2 population derived from imbibed seeds irradiated with argon ions (2.5 Gy, 95 MeV/n, LET: 286 keVµm−1 ). To
determine the mode of inheritance of the early ﬂowering trait, we produced F2 progenies derived froma cross between Ar-G150 and their original variety,
Nipponbare. We grew Nipponbare, Ar-G150, and theF2 progenies in a greenhouse under natural photoperiod conditions from June 17, 2016, and recorded theheading date of each plant. The heading date of Nipponbare were from September (Sept.) 2nd to Sept.
6th. The heading date of Ar-G150 were from August (Aug.) 23rd to Aug. 26th, approximately 10 days
earlier than Nipponbare. Segregation for the earlyﬂowering phenotype was observed in F2 progenies, i.e.,seven F2 plants showed normal ﬂowering (the heading dates were from Sept. 2nd to Sept. 5th), and 23
F2 plants showed early ﬂowering (the heading dates
were from Aug. 23rd to Aug. 27th). The segregationof normal- and early-ﬂowering phenotypes in the F2progenies (7:23) showed a good ﬁt to a 1:3 ratio (thetwo-tailed p-value from Fisher’s exact test was 1.00),
indicating that Ar-G150 possessed a single dominant
mutated gene with an early-ﬂowering trait. To characterize the mutated phenotype in detail or determine
the causative gene of early ﬂowering, the homozygousline for the mutated gene is needed. Thus, we cultivated 16 F3 lines (approximately 20 plants per line)
derived from the self-pollination of early-ﬂowering F2plants to select the homozygous line using a paddy
ﬁeld in 2019. In 5 out of the 16 F3 lines, all F3 plants
exhibited early ﬂowering, indicating that the mutatedgene in their parental plant was homozygous. In the remaining 11 lines, segregation for the early- and normalﬂowering phenotype was observed in F3 plants, indicating that the mutated gene in the parental plant washeterozygous. The number of homozygous F2 and heterozygous F2 (5:11) showed a good ﬁt to a 1:2 ratio (thetwo-tailed p-value from Fisher’s exact test was 1.00).
∗1∗2

RIKEN Nishina Center
Graduate School of Agricultural Science, Tohoku University- 210 -

Fig. 1. Days to heading of WT and Ar-G150 grown undera short-day condition. Values are means ± standard
error (n = 5). Student’s t-test was used to compare thetwo groups.

These results indicated that the early-ﬂowering character was determined by a single gene.
Using the homozygous F3 plants, we started tocharacterize the early-ﬂowering phenotype of Ar-G150.
First, we determined the days to heading under a controlled photoperiod condition using a growth chamber
to reveal whether the mutated gene aﬀects the photoperiod response. We grew Nipponbare and Ar-G150
plants under a short-day condition (10 h light/14 hdark), and measured the days to heading. Since rice
is a short-day plant and the critical photoperiod of
Nipponbare is estimated to be 15.6 h,2) this condition
prompts rice plants to develop ﬂowers. Under this condition, the days to heading of Ar-G150 (57.8 ± 1.0 d,
average ± standard error) was slightly less than thedays to heading of Nipponbare (61.2 ± 1.2 d), althoughno signiﬁcant diﬀerences were observed between thedays to heading of both lines (p > 0.05), suggesting that the mutated gene have little or no eﬀect ofpromoting ﬂowering under the short-day conditions(Fig. 1). We also started to perform the whole genome
re-sequencing analysis of homozygous F3 mutants toreveal the causative gene. The information of thecausative gene will help us understand the mechanism
to control the heading date of rice in more detail.
References
1) B. Wang, J. Li, Plant Cell 31, 1416 (2019).
2) T. Horie, H. Nakagawa, Jpn. J. Crop Sci. 59, 687 (1990).

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Approach toward isolating early-heading mutants from Tana Toraja
local aromatic rice “Pare Bau” irradiated with argonand carbon-ion beams
A. M. Okasa,∗1,∗2,∗3 M. Riadi,∗1 T. Sato,∗2,∗3 K. Toriyama,∗2 K. Ishii,∗3 Y. Hayashi,∗3
T. Abe,∗3 and R. Sjahril∗1,∗4
Tana Toraja is a mountainous area in the northernpart of South Sulawesi, Indonesia. The area has been
known as an aromatic-rice-producing area.1) The aromatic rice cultivar “Pare Bau” has good grain quality
and fragrant aroma, making it relatively expensive inthe market, but it has several disadvantages including
late heading dates and long stems for modern farming
systems. The heading date can be determined by thebasic vegetative phase (BVP) and photoperiod sensitive phase (PSP).2) Indonesian rice cultivated in mountain areas has a relatively short PSP and relatively long
BVP. This study aims to isolate early heading mutant
lines induced by heavy-ion-beam irradiation.
Dry seeds of Tana Toraja local aromatic rice cultivar(Oryza sativa L. “Pare Bau”) were irradiated with carbon ions (30 keV/µm) and argon ions (300 keV/µm) in
the RI-beam factory, RIKEN Nishina Center, Japan.
Owing to a limited range of Ar-ion beams, seeds for Arion irradiation needed to be packed in a single layer.
For this purpose, a sponge was bedded as a bottom
plate in a plastic rectangular box (75 × 50 × 18 mm).
The doses of Ar-ion and C-ion irradiation were 10 and
150 Gy, respectively.3,4) We investigated the heading
dates of Pare Bau lines irradiated with Ar and C ions
(PB-A and PB-C, respectively).
In May 2016, M1 seeds (1000 seeds of PB-A and 1000
seeds of PB-C) were germinated and sown in seedlingpots and grown in a greenhouse for three weeks. The
germination rates of M1 seeds were 53% for PB-C and
49% for PB-A, while that of the wild-type control was
70%. The seedlings (94 PB-A and 79 PB-C plants)
were transplanted in the paddy fields of Hasanuddin
University (S: 5◦ 7′ 53.50′′ E: 119◦ 28′ 57.97′′ ; 20 m above
sea level) in June 2016. Owing to poor establishmentof seedlings, only small amounts of M1 plants (13 PBA and 13 PB-C plants) set more than 50 seeds inNovember 2016. In June 2017, 50 M2 seedlings perline were transplanted in the paddy field of mountainous Enrekang Regency (S: 3◦ 19′ 47.44′′ E: 119◦ 50′ 1.57′′ ;650 m above sea level) neighboring Tana Toraja Regency. Based on heading dates at least one week earlier ʢ<119 daysʣthan those of the wild-type control(>125 days), we selected 82 PB-A and 26 PB-C plants
as mutant candidates. From these M2 plants, we sampled M3 seeds with relatively large grain weights per
∗1
∗2
∗3
∗4

Faculty of Agriculture, Hasanuddin University
Graduate School of Agricultural Science, Tohoku University
RIKEN Nisina Center
Corresponding author- 211 -

Fig. 1. Phenotypes of early-heading mutants induced byheavy-ion-beam irradiation in the paddy field of Enrekang Regency.

panicle from 18 lines of PB-A and one line of PB-C in
October 2017. In May 2018, 50 M3 seedlings per line
were transplanted in the paddy field of Enrekang Regency. Heading dates of the M3 individual plants andwild-type control plants were recorded for the first 25
plants showing relatively early heading. The days toheading of the wild-type control was 126 to 130 days
with an average of 128 days, while those of the following nine lines were 108 to 126 days with an average of 117 to 121 days, which were over one weekless than that of the wild-type control (Fig. 1). Theselines are PB-A.5.3.45, PB-A.6.1.9, PB-A.7.1.30, PBA.12.2.4, PB-A.12.2.12, PB-A.14.2.14, PB-A.14.3.1,
PB-A.14.4.3, and PB-C.20.1.49. We expect these lines
to contain mutant candidates. Genetic analysis will be
performed for M4 lines and their hybrids with the wild
type to investigate the mutated genes responsible forearly heading.
Acknowledgements
The authors would like to express their deepest
gratitude to the Directorate General of Resources
for Science, Technology and Higher Education (DGRSTHE), the Ministry of Education and Culture forEnhancing International Publication Program throughthe PMDSU Scholarship.
References

1) H. Sahardi, F. Djufry, Proc. National Seminar on Genetic Resources of Agriculture, (2013) pp. 1.34–43.
2) B. S. Vergara, T. T. Chang, The Flowering Response of
the Rice Plant to Photoperiod: A Review of the Literature, 4th Edition (IRRI, Philippines, 1985).
3) Y. Hayashi et al., RIKEN Accel. Prog. Rep. 50, 27(2017).
4) Y. Hayashi et al., RIKEN Accel. Prog. Rep. 51, 238(2018).

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

A novel domain of LONG GRAIN 1 in rice possesses transcriptional
activation activity
H. Abe,∗1 R. Morita,∗1 Y. Shirakawa,∗1 Y. Hayashi,∗1 H. Ichida,∗1 and T. Abe∗1
We previously identiﬁed the gene LONG GRAIN 1(LIN1 ), which regulates seed development, and a mutation of the gene (lin1 ), which causes long grain size.1)
The lin1 mutant was obtained from rice (Oryza sativa
L. ssp. japonica cv. Nipponbare) M2 population derived
from imbibed seeds irradiated with argon-ion beams(5 Gy, 95 MeV/nucleon, LET: 286 keV m−1 ) in the
RIKEN RI-beam factory.1) LIN1 is predicted to encode
the 412 amino acid protein, LIN1, with calculated MW
42,579 and pI 10.8. InterPro search of LIN1 revealed
that LIN1 has no known functional domain and/or motif.
To gain more insight into LIN1 functions for seeddevelopment, we conducted yeast two-hybrid screening
for isolation of LIN1 interaction proteins (LIPs).2) We
obtained several LIPs, and one LIP was MADS1, thetranscription factor for ﬂoral organ development. During the course of the yeast two-hybrid assay for LIN1
and MADS1 interaction, we noticed that mutant lin1
was more actively bound to MADS1 than full length
LIN1 (Figs. 2.3 and 4). As sequence alignments of
LIN1 homologs in rice and Arabidopsis revealed that
LIN1 has 5 short stretch conserved domains (I∼V)(Fig. 1.1), we divided LIN1 into several N- and Cterminal fragments, each containing several conserved
domains, and performed yeast two-hybrid assays. Unexpectedly, yeast cells transformed with BD-fusion construct of N-terminal fragment of LIN1-M120 (Fig. 1.3)
containing only conserved domain I were grown on aselection plate of SD/-Leu/-Trp/-His/-Ade not only inthe presence of AD-MADS1 but also in an AD-empty
construct (Figs. 2.6 and 7). On the contrary, the BD12
3
4

Fig. 1. Schematic diagram of LIN1, lin1 and LIN1 fragmentprotein sequence. Dark blue color with Roman numerals(I∼V) indicates positions of conserved domains. 1. Fulllength LIN1 protein (M1-G412). 2. Mutant lin1 proteincaused by 1 bp deletion of LIN1 gene. The frame shift
mutation result for an extended sequence (orange color)and a premature stop codon. 3. N-terminal fragmentof LIN1-M120 containing the domain I. 4. C-terminal
fragment of P121-LIN1 without the N-terminal portion(3) of LIN1.
∗1

RIKEN Nishina Center ! ! !

!

%

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

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 %

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Fig. 2. Yeast two-hybrid assays. Combination of BD-fusion
constructs and AD-fusion constructs are indicated (1-8).
Both constructs were transformed into Y2H-Gold yeast
competent cells, and growth assays on SD/-Leu/-Trp andSD/-Leu/-Trp/-His/-Ade plates were performed.

fusion construct of the C-terminal fragment of P121LIN1 (Fig. 1.4) had no such activity (Fig. 2.8). These
results indicate that the N-terminal fragment of LIN1M120 had transcriptional activation activity for the reporter gene expression in yeast cells.
Considering the results, we hypothesize that LIN1
might be a novel transcription factor family protein with
N-terminal transcriptional activation activity for regulating seed development. Elucidation of LIN1-regulated
target genes should be provided for important information not only for understanding seed development but
also for application of plant breeding.
References

1) R. Morita et al., Mol. Breeding 39, 135 (2019).
2) H. Abe et al., unpublished.

- 212 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Establishment of large mutant lines on rotifer
using heavy-ion-beam irradiation
K. Tsuneizumi,∗1 M. Yamada,∗1 K. Ichinose,∗1 H. Ichida,∗1 and T. Abe∗1
In larviculture, rotifers (Brachionus plicatilis sensestrict) are generally used as the initial feed for hatchedlarvae,1) while larger preys (e.g., Artemia) are neededwith larval growth. The improper management of feed
size and density results in mass mortality, a high incidence of morphologically abnormal development, and asubstantial depletion of ﬁsh larvae.2) To improve the survival and growth of ﬁsh larvae, prey of appropriate size
between those of rotifer and Artemia is needed. The aimof this study was to apply heavy-ion-beam-based mutation breeding techniques3,4) for the selection of rotifer
mutants with larger body sizes.
The size distributions of the lorica length of rotifers
are 170–320 µm in individuals carrying amictic eggs.
The next food item Artemia nauplii has a body length of
400–1,000 µm, and thus, there is a large size gap (320–400 µm) between rotifer and Artemia nauplii. The rotifer strain is widely divided into two types, obligate andcyclically parthenogenesis, based on their life cycle.5) In
aquaculture facilities, the intensive mass culture of live
food rotifers is performed via parthenogenetic reproduction to induce their rapid proliferation. The Notojima
strain is known as the largest rotifer strain used in Japanand has obligate parthenogenesis. Based on these characteristics, this study used the Notojima strain as theraw material for ion-beam irradiation.
In our previous study, we measured the biological effect of heavy-ion-beam irradiation on rotifers under different conditions.6) In this study, a large-scale screening
method was developed, and mutant lines with increased
body sizes were selected using the length of the lorica as
indicators. Heavy-ion-beam irradiation was performed
using carbon (C) (1.62 GeV, LET = 23 keV/µm) at six
irradiation doses of 100, 150, 200, 300, 400, and 600 Gy
and argon (Ar) (3.8 GeV, LET = 312 keV/µm) at six
irradiation doses of 25, 50, 75, 100, 150, and 200 Gy. After irradiation, morphometric characteristics were compared with control groups without irradiation.
The results of categorising lorica lengths of the control and the 56 selected larger mutant strains are shownin Fig. 1. Strains were classiﬁed according to their average lorica length: Class I for 340–350 µm, Class II for
350–360 µm, and Class III for 360–370 µm. Class I corresponds to over 11% elongation, Class II to 15%, andClass III to 18% compared to the lorica length of thecontrols. The large mutant lines from 1968 rotifers irradiated with C-ion beams were categorized as follows:
30 lines to Class I, 19 lines to Class II, and 3 lines toClass III. In the large mutant lines from 1080 rotifers irradiated with Ar-ion beams, there were 3 lines in Class I∗1

Fig. 1. Comparison of lorica lengths between large mutant
strains and the control.

and 1 line in Class II (Fig. 1). Steel’s multiple comparison tests showed a diﬀerence at 0.001 signiﬁcancelevel in lorica lengths of all larger mutant strains fromClass I to Class III compared with the control group(305.6 ± 3.0 µm).
The size range of lorica length of the larger mutant
strains was 320–400 µm, which is not covered by thesize ranges of the wild-type rotifer and Artemia nauplii in seedling production (Fig. 1, red bars). Various
larger mutant strains have been established by mutagenesis with heavy-ion-beam irradiation, and these strains
may help reduce the mass mortality of domestic ﬁsh if
used during the intermediate feeding stage between rotifers and Artemia nauplii.
The lorica lengths of all large mutant strains showedsigniﬁcant diﬀerences compared to the control group(Steel’s multiple comparison tests, p < 0.001, n = 20).
Boxplots indicate the lorica lengths of rotifers (n = 20).
Strains were separated into classes according to the average lorica length.
References

1) S. Mills et al., Hydrobiologia 796, 39 (2017).
2) T. Kotani et al., J World Aquac. Soc. 40, 383 (2009).
3) T. Abe et al., in Plant Mutation Breeding and Biotechnology, edited by Q. Y. Shu et al. (CABI, Oxfordshire,2012), p. 99.
4) A. Tanaka et al., J. Radiat. Res. 51, 223 (2010).
5) T. Yoshinaga et al., Hydrobiologia 412, 103 (1999).
6) K. Tsuneizumi et al., RIKEN Accel. Prog. Rep. 52, 221(2019).

RIKEN Nishina Center- 213 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Contribution of multiple DNA repair pathways in Arabidopsis thaliana
dry seeds after heavy-ion-beam irradiation
K. Ishii,∗1 S. Ohbu,∗1 M. Yamada,∗1 and T. Abe∗1
Heavy-ion-beam irradiation induces DNA doublestrand break (DSB) which is critical damage to cellular proliferation. DSB is repaired by two main
pathways: homologous recombination (HR) repair,which is homology-dependent and error-free; canonicalnon-homologous end-joining (C-NHEJ), which is Kudependent and potentially error-prone and by a recently identiﬁed error-prone pathway, alternative nonhomologous end-joining (A-NHEJ). Which pathway is
chosen is dependent on the phase of cell cycle and theinitiation of DNA end resection.1) HR is preferred during the S/G2 phase in the cell cycle because sister chromatids can be used as homologous templates. C-NHEJ
functions through the cell cycle and especially in G1 andG2 phase. A-NHEJ functions when the key factors of
C-NHEJ are absent, essentially in the S phase. Because
most embryo cells in dried seeds are in the G1 phase,2)
it is possible that C-NHEJ will mainly function after
heavy-ion-beam irradiation. In this study, we irradiatedheavy-ion-beams on three diﬀerent lines: a wild type, a
C-NHEJ-deﬁcient line, and a HR-deﬁcient line, and wemeasured mutation rates to reveal how each DSB-repair
pathway functions.
We obtained Arabidopsis thaliana seeds of SALK_
123114 line with a T-DNA insertion in the Ku70 gene(a Ku70(−/−) mutant) and SALK_038057 line withthat in the Rad 54 gene (a Rad 54(−/−) mutant) from
Nottingham Arabidopsis Stock Centre (NASC) andused them as the C-NHEJ-deﬁcient and HR-deﬁcientlines, respectively. Dry seeds of Col-0 line (wild type),
the Ku70(−/−) mutant, and the Rad 54(−/−) mutant were irradiated with 12 C6+ (135 MeV/nucleon)
ions at doses ranging from 0 to 600 Gy. The LETof C-ion beams were controlled to 30 keV/µm. After the irradiation, ﬂowering rate (number of ﬂowering plants per total number of incubated seeds) were
measured as survival rate, as previously described.3)
We also obtained seeds of CS16118 line with a TDNA insertion in the APG3 gene (an APG3(+/−)
mutant) from NASC. The APG3(+/−) mutant
was crossed with the Ku70(−/−) and Rad 54(−/−)
mutants to produce Ku70(−/−)APG3(+/−) andRad 54(−/−)APG3(+/−) mutants in the F2 generations, respectively. Dry seeds of the APG3(+/−) line
(regarded as a wild type), Ku70(−/−)APG3(+/−) line,
and Rad 54(−/−)APG3(+/−) line were irradiated with
12 6+
C (135 MeV/nucleon) ions at 60 Gy. The LET of
C-ion beams was controlled to 30 keV/µm. After theirradiation, appearance ratio was measured as mutation
rate, as previously described.4)
The ﬂowering rates of un-irradiated control of the wild
∗1

RIKEN Nishina Center

Fig. 1. Mutation rate after C-ion-beam irradiation at 60 Gy.
**: p < 0.01.

type, C-NHEJ-deﬁcient line, and HR-deﬁcient line were
not lower than 0.99. In the wild type, the ﬂowering
rate was 0.80 even after 600 Gy-irradiation, while in the
Rad 54(−/−) mutant, the rate was reduced to 0.30. In
the Ku70(−/−) mutant, there was no individual ﬂowered only after 120 Gy-irradiation. It is suggested thatboth C-NHEJ and HR pathways are involved in DNA
repair after heavy-ion-beam irradiation and the C-NHEJ
pathway has a greater contribution.
While the mutation rate of the wild type was 0.7%,
those of the HR-deﬁcient and C-NHEJ-deﬁcient lines
were signiﬁcantly (p < 0.01) higher: 2.0% and 2.9%,
respectively. It is possible that in the HR-deﬁcient lines,
DSBs usually repaired by the HR pathway are repairedby the C-NHEJ pathway. Although the diﬀerence between the HR-deﬁcient and C-NHEJ-deﬁcient lines was
not signiﬁcant, the C-NHEJ-deﬁcient line showed higher
mutation rate. It is suggested that when the C-NHEJ
pathway is absent, DSBs are repaired not by the errorfree HR pathway but by the error-prone A-NHEJ pathway, resulting in higher mutation rate.
In this study, it was suggested that DSBs induced indry seeds of A. thaliana by heavy-ion beams are mainly
but not entirely repaired by the C-NHEJ pathway. One
possibility is that the embryo cells in the dry seeds are
not uniform in the G1 phase. Another is that DSBs
are not completely repaired in the G1 phase but in thefollowing phase beyond the cell cycle check points.
References

1) C. S. Spampinato, Cell. Mol. Life Sci. 74, 1693 (2017).
2) R. D. de Castro, H. W. M. Hilhorst, R. Bras. Fisiol. Veg.
12, 105 (2000).
3) Y. Kazama et al., Plant Biotechnol. 25, 113 (2008).
4) Y. Kazama et al., Plant Biotechnol. 29, 441 (2012).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 53

Ion-microbeam irradiation to damage DNA in RPE cell nucleus withtapered glass capillary optics at Pelletron facility
T. Ikeda,∗1 M. Sakai,∗2,∗1 K. Takemoto,∗2,∗1 A. Shibata,∗3 M. Izumi,∗1 and M. Uesaka∗2
Cell irradiation experiments with ion microbeams havestarted at a new beamline of the RIKEN Pelletron accelerator facility in the Nishina R&D Building. The purpose of the experiments is to investigate the dynamics
of the accumulation of restoration proteins after DNA
double-strand breaks (DSB). The microbeam irradiation
allows artiﬁcial DNA damage, which deﬁnes the time
zero for the accumulation of repair proteins. To create DSB eﬃciently, ions with high linear energy transfer(LET) should be used. Figure 1 shows the LET in waterfor H and He ions with an energy E below 5 MeV. The H
and He ions have maximum LETs of 80 and 240 keV/µm,
respectively, just before stopping. If we use He ions withan energy of 4.5 MeV, an LET of more than 100 keV/µm
is available through an ion range of 27 µm. The LET
value is large enough to create DSB.
The irradiation was performed at the BL-W30 beamline employing a single tapered glass capillary optics atthe beam port, where the microbeam was emitted in thehorizontal direction. A He-ion beam was accelerated to
4.5 MeV with a tandem accelerator (Pelletron 5SDH-2,
1.7 MV max.), and it entered a glass capillary having
an outlet diameter and end window thickness of 11.4 µm
and 8.6 µm, respectively. The details of the capillary microbeam at an old beamline of our facility are reported
elsewhere.1,2) The target was nuclei of retinal pigment
epithelial (RPE) cells cultivated in a liquid medium. The
cells were fully conﬂuent in petri dishes, the glass bottoms of which were marked to ﬁnd irradiated cells for the
ﬂuorescence observation after the irradiation. As shownin Fig. 2(a), the petri dish was positioned at an angle ofapproximately 45◦ to the capillary axis. To maintain thecells in the dish ﬁlled with the medium, it was dripped
onto the bottom of the dish at a speed controlled bya peristaltic pump. The microbeam intensity was set
to approximately 15 ions/s, which was conﬁrmed before
and after the irradiation. The irradiation distance be-

Fig. 1. Comparison of the LETs of H and He ions in waterwith an energy between 0 and 5 MeV.
∗1
∗2
∗3

RIKEN Nishina Center
The Graduate School of Engineering, Univ. of Tokyo
Gunma University Initiative for Advanced Research (GIAR),
Gunma Univ.

Fig. 2. (a) Cell irradiation with a glass capillary. The angle
was set to approximately 45◦ with respect to the capillaryaxis. (b) Irradiated RPE cell nucleus with DSB points.

tween the capillary outlet and the cells was set to several
micrometers. The distance was always monitored by amicroscope above the irradiation point. Each dish was
moved for 3–8 min to irradiate the cells on a line acrossthe dish. The total number of dishes was four. Afterthe irradiation, 30 min was spent for the repair process
based on an enzymatic reaction. Subsequently, the cells
were ﬁxed with 3% paraformaldehyde (PFA)-2% sucrosein phosphate-buﬀered saline (PBS), followed by washingwith PBS. Next, the dishes were ﬁlled with PBS for delivery to Gunma University for observation by an optical
microscope with three-dimensional structured illumination, 3D-SIM, microscopy (DeltaVision OMX version 4,
GE Healthcare).
Figure 2(b) shows a bottom view of one of the irradiated cells. The blue area corresponds to the cell nucleus labeled by DAPI. The bright blue points are DSB
positions where phosphorylated histone H2AX was laR 488 by the immunoﬂuorescence
beled with Alexa Fluor⃝
method. The DSB points are clearly aligned on a linewith extremely low background ﬂuorescence. The line is
expected to be a He ion track stopping at or penetrating
the nucleus. The photo is one of the z-sliced photos witha slice step ∆z of 0.25 µm.
The brightness information of each pixel in the images
was stored as a 3D map. Using the map, the directionsof all ion tracks and the density distributions of DSB andother restoration proteins were extracted. The time evolution of repair of DSB as a function of the distance fromthe ion track will be obtained in the next experiment bychanging the time between irradiation and ﬁxing.
References

1) V. Mäckel et al., Rev. Sci. Instrum. 85, 014302 (2014).
2) T. Ikeda et al., Quantum Beam Sci. 4, 22 (2020).

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IV. OPERATION RECORDS

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

Electric power consumption of RIKEN Nishina Center in 2019
E. Ikezawa,∗1 Y. Watanabe,∗1 H. Yamasawa,∗1 and O. Kamigaito∗1
The average hourly electrical power consumption of
the RIKEN Nishina Center (RNC) for each day in 2019is shown in Fig. 1. The total electrical power consumption by RNC in 2019 was 56,928 MWh, which was 5%
higher than that in 2018. When RI Beam Factory(RIBF) experiments using an uranium (238 U) beam

were conducted, the maximum commercial electrical
power supply to the RIKEN Wako campus reached20.05 MW with a cogeneration system (CGS) output of
6.0 MW on November 11, 2019, and the maximum electrical power consumption of RNC reached 15.8 MW on
November 27, 2019.

Fig. 1. Average hourly electrical power consumption of RNC for each day in 2019.

∗1

RIKEN Nishina Center- 217 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

Operation report of the ring cyclotrons in the RIBF accelerator complex
N. Tsukiori,∗1 K. Ozeki,∗2 T. Dantsuka,∗2 M. Fujimaki,∗2 T. Fujinawa,∗2 N. Fukunishi,∗2 S. Fukuzawa,∗1
M. Hamanaka,∗1 H. Hasebe,∗2 Y. Higurashi,∗2 E. Ikezawa,∗2 H. Imao,∗2 S. Ishikawa,∗1 O. Kamigaito,∗2
Y. Kanai,∗2 M. Kase,∗2 M. Kidera,∗2 K. Kobayashi,∗1 M. Komiyama,∗2 R. Koyama,∗1 K. Kumagai,∗2 T. Maie,∗2
M. Nagase,∗2 T. Nagatomo,∗2 T. Nakagawa,∗2 M. Nakamura,∗2 T. Nakamura,∗1 M. Nishida,∗1 M. Nishimura,∗1
J. Ohnishi,∗2 H. Okuno,∗2 N. Sakamoto,∗2 J. Shibata,∗1 K. Suda,∗2 A. Uchiyama,∗2 S. Watanabe,∗2
T. Watanabe,∗2 Y. Watanabe,∗2 K. Yadomi,∗1 K. Yamada,∗2 and H. Yamasawa∗2
The operation report of the ring cyclotrons in the
RIBF accelerator complex from Jan. to Dec. 2019 is presented here. Table 1 presents a summary of the beams
accelerated by these cyclotrons. The availability in thetable is deﬁned by the ratio of the actual beam time tothe scheduled beam time, which is an index of the stable
operation of accelerators. In calculating each availability,
for beam times that were completed earlier than scheduled, the scheduled times are identiﬁed with the actual
times. Multiple experiments supplying identical beams
are shown as a block.
The total beam supply time (actual beam time) was
1581.8 h. The ratio of beam times between the experiments conducted in the old facility (RARF) and those
conducted in the new facility (RIBF) was 8% and 92%.
In the RARF, the actual beam time was 128.0 h, andthe availability was 105.6%. Beams were stably supplied
as usual. In addition to the beams listed in Table 1,
experiments for synthesizing the 119th element using a51
V beam were conducted as a closed beam time under
the Nishina Center Director.
In the RIBF, three beam services were conducted. The
total beam time was 1453.8 h, and the availability was
92.2%. For the supply of 238 U beams, a maximum beam
intensity of 94.2 particle nA was achieved, which was
1.3 times higher than the value of 72.0 particle nA in
a previous beam time in Oct. 2018. A second hightemperature oven1) was added in the 28-GHz superconducting electron cyclotron resonance ion source, which
has contributed to an increase in intensity and the stabilization of the uranium beam. Furthermore, the stabilization of the magnetic ﬁeld of the IRC has also contributed to a stable beam intensity and an improvementin the transmission eﬃciencies for RRC and fRC.2) For

the supply of 124 Xe beams, a maximum beam intensityof 173 particle nA was achieved, which was 1.7 times
higher than the value of 102 particle nA in a previous
beam time in Apr. 2016.
The improvement of the acceleration voltage by the
upgrade of the RRC resonators3) performed in 2018 hascontributed to the remarkable enhancement in the intensity of beams delivered to the RIBF. In 18.25-MHz
operations, both resonators were operated with an acceleration voltage of over 138 kV. Owing to an improvement of the shunt impedance, a signiﬁcant reduction wasachieved in the frequencies of the voltage breakdown bydischarge and in the high-voltage trips of the vacuum
tube. After all beam times scheduled in the ﬁrst halfof this ﬁscal year had been ﬁnished, a high-power test
was performed. Both resonators achieved an acceleration voltage of 160 kV, which was twice that before theupgrade.
However, after the resonator upgrade of RRC, waterleakages occurred in cooling water channels of the stems
several times in 2018 and once in 2019. We spent 4–
5 days repairing the leakage point by welding. Water
leakage is a very serious problem that hinders the stable operation of RIBF. Therefore, during this summer
maintenance period, an intensive investigation to ﬁndtiny leaks and the treatment of all the leaks found in theinvestigation were conducted. Since then, no degradations of vacuum occurred due to water leakage from thestems.
References

1) J. Ohnishi et al., RIKEN Accel. Prog. Rep. 52, 109 (2019).
2) R. Koyama et al., in this report.
3) K. Yamada et al., RIKEN Accel. Prog. Rep. 52, 13 (2019).

Table 1. Summary of the accelerated beams in 2019.

∗1∗2

SHI Accelerator Service Ltd.
RIKEN Nishina Center- 218 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

RILAC operation
E. Ikezawa,∗1 T. Ohki,∗2 M. Kase,∗1 T. Nakagawa,∗1 N. Sakamoto,∗1 H. Okuno,∗1 N. Fukunishi,∗1
Y. Watanabe,∗1 M. Komiyama,∗1 A. Uchiyama,∗1 T. Maie,∗1 M. Nagase,∗1 M. Fujimaki,∗1 T. Watanabe,∗1
H. Hasebe,∗1 H. Imao,∗1 K. Ozeki,∗1 K. Suda,∗1 Y. Higurashi,∗1 K. Yamada,∗1 S. Watanabe,∗1 M. Kidera,∗1
T. Nagatomo,∗1 K. Kumagai,∗1 T. Nishi,∗1 H. Yamauchi,∗2 K. Oyamada,∗2 M. Tamura,∗2 A. Yusa,∗2
K. Kaneko,∗2 and O. Kamigaito∗1
The RIKEN heavy-ion linac (RILAC) was operated
in December 2019. Some statistics regarding the operation of RILAC from January 1 to December 31, 2019are presented in Table 1.
Table 2 lists the beam service times in the standalone
mode of RILAC in 2019.
The following works and tests to upgrade RILAC
have been in progress at the LINAC building during
the reporting period. The details are described elsewhere in this progress report.
(1) Performance tests were conducted at the new
28-GHz superconducting electron cyclotron resonance ion source (SC 28-GHz ECR ion source).
Table 3 lists the operation time of the performance tests in 2019.
(2) The section after the A2 cavity was reconstituted. The necessary preparation for the installation of a superconducting RILAC (SRILAC), middle-energy beam transport (MEBT),and high-energy beam transport (HEBT) was
conducted.
We performed the following maintenance works during the reporting period.
(1) In the radio-frequency systems, DC high-voltage
power supplies were subjected to annual inspection. The major components with mechanicalparts were subjected to simple inspection.
(2) The water pumps were subjected to simple inspection. All cooling towers were subjected tomonthly inspection.

Table 1. Statistics of RILAC operation from January 1 to
December 31, 2019.

∗1∗2

Operation time of RILAC

43.7 hMechanical problem

0.0 hStandalone RILAC

23.9 hInjection into RRC

0.0 h

Total beam service time of RILAC

23.9 h

RIKEN Nishina Center
SHI Accelerator Service Ltd.

- 219 -

(3) All turbomolecular pumps were subjected tosimple inspection. Cryogenic pumps used forcavities 3, 4, and 6 and the standby units were
overhauled.
(4) All magnet power supplies were subjected tosimple inspection.

Table 2. Beam service time of standalone RILAC in 2019.
Beam course

Total time (h)%In acceleration room

23.9

100.0

e2

0.0

0.0

e3

0.0

0.0

Total

23.9

0.0

Table 3. Operation time of the SC 28-GHz ECR ion sourcein 2019.
Ion

Mass

Total time (h)

Ar

40

463.4

Ca

40

650.6

V

51

403.0

Zn

70

1017.6

Total

2534.6

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

Operation report on the RIKEN AVF cyclotron for 2019
M. Hamanaka,∗1 K. Suda,∗2 M. Fujimaki,∗2 N. Fukunishi,∗2 S. Fukuzawa,∗1 A. Goto,∗2 H. Hasebe,∗2
Y. Higurashi,∗2 E. Ikezawa,∗2 H. Imao,∗2 S. Ishikawa,∗1 O. Kamigaito,∗2 K. Kaneko,∗1 M. Kase,∗2 M. Kidera,∗2
K. Kobayashi,∗1 M. Komiyama,∗2 Y. Kotaka,∗3 R. Koyama,∗1 K. Kumagai,∗2 T. Maie,∗2 M. Nagase,∗2
T. Nagatomo,∗2 T. Nakagawa,∗2 T. Nakamura,∗1 M. Nishida,∗1 M. Nishimura,∗1 J. Ohnishi,∗2 H. Okuno,∗2
Y. Oshiro,∗3 K. Ozeki,∗2 N. Sakamoto,∗2 J. Shibata,∗1 N. Tsukiori,∗1 A. Uchiyama,∗2 S. Watanabe,∗2
T. Watanabe,∗2 Y. Watanabe,∗2 K. Yadomi,∗1 and K. Yamada∗2
The yearly report on the operation of the RIKEN
AVF cyclotron (denoted as AVF hereafter) for the period
January - December 2019 is presented here. AVF hasfour beam courses as stand-alone operations: C03 (RIproduction), E7A (CRIB), E7B (student experiment),
and C12 (a new course for nuclear physics). The beamcourses are shown schematically in Fig. 1. In addition,
AVF is used as an injector of RRC. In this mode, there
are three beam delivery schemes: RRC-RARF, RRCIRC-E5, and RRC-SRC.
The yearly operation statistics and beams acceleratedusing AVF are summarized in Tables 1 and 2, respectively. The total operation time was 3603 h, of which
3166 h was dedicated to AVF stand-alone experiments
and 437 h to operations as the injector of RRC. The
latter decreased by 1114 h compared with that in thelast year. New experiments were conducted at the C12
course in the E7 experimental hall. It is remarkable that
there was no trouble in AVF during beam services in thisyear. The phase slit that leaked cooling water in the lastyear was replaced by a new one during a maintenanceperiod in the summer. In the same period, the SC-ECR
ion source operated for AVF since 2008 was removed owing to the diﬃculty of maintenance. As an alternative,

the 18 GHz ECR ion source used for RILAC to produce intense metallic ions was installed. At the end of
2019, the ion source became operational as an injector
for AVF.
Table 1. Comparison of AVF operation statistics with thatin the previous year.
AVF stand-alone operation
Tuning of AVF[h][h]
Trouble of AVF
C03 exp.
[h][h]
E7A exp.
[h]
E7B exp.
[h]
C12 exp.
Sub total[h]

AVF operation as injector of RRC
Tuning of AVF[h]Trouble of AVF[h]RRC-RARF exp.
[h]
RRC-IRC-E5 exp.
[h]
Sub total
[h]
Total

[h]

2018
886
6
2067
262
274
0

2019
1314
0
873
789
152
36

3489

3166

2018
132
1
600
820
1551

2019
117
0
239
81
437

5042

3603

Table 2. AVF beam list in 2019.

C12

Fig. 1. Overview of the AVF cyclotron with ion sources,
each experimental course, and the beam transport line
to RRC.
∗1∗2∗3

SHI Accelerator Service Ltd.
RIKEN Nishina Center
Center for Nuclear Study, the University of Tokyo- 220 -

Particle
Energy [MeV/nucleon]
AVF stand-alone operation
p
12
d
12
4
He
6.5
4
He
7.25
4
He
12.5
6
Li
11.2
7
Li
6
10
B
7
18
O
6
18
O
6
18
O
6
18
O
7
19
F
6
20
Ne
5
24
Mg
7
24
Mg
8
AVF operation as injector of RRC
12
C
7
14
N
7
40
Ar
5.19
56
Fe
5

Course/Scheme
C03
C03
E7B
C03, E7B
C03
E7A
C03, E7B
E7A
C03
C03
C12
C12
C03
E7B
E7A
E7A
RRC-RARF
RRC-RARF
RRC-IRC-E5
RRC-RARF

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

Present status of the liquid-helium supply and recovery system
T. Dantsuka,∗1 H. Okuno,∗1 M. Nakamura,∗1 S. Tsuruma,∗1 M. Takahashi,∗1 M. Kuroiwa,∗1 M. Ohshima,∗2
H. Miura,∗2 H. Shiraki,∗2 H. Hirai,∗2 K. Kimura,∗2 M. Haneda,∗2 A. Mikami,∗2 M. Nagano,∗2 and H. Hazama∗2
The liquid-helium supply and recovery system,1)
which can produce liquid helium at a liquefaction rateof 200 L/h from pure helium gas, had been under stable
operation since the beginning of April 2001. As operation failures due to aging-related deterioration has increased in recent years, a new liqueﬁer was introduced
in 2017. It can produce liquid helium at a liquefaction
rate of 220 L/h from pure helium gas. In the summerof 2018, the older helium liqueﬁer has failed. However,with the new helium liqueﬁer, we can supply liquid
helium without stoppage.
The volumes of liquid helium supplied each year
from 2001 to 2018 are shown in Fig. 1. The supplied
volume gradually increased from 20,000 L to 180,000 L.
Owing to a malfunction, the supplied volume decreased
in 2014.

The purity of helium gas recovered from the laboratories is gradually deteriorating. At present, theimpurity concentration in the recovered gas is about
500 ppm. The impurity concentration does not affect the liquefaction operation, but it is necessary toobserve the progress. The volumes of helium gas recovered from each building in Wako campus were measured. The recovery eﬃciency, which is deﬁned as theratio of the amount of recovered helium gas to theamount of supplied liquid helium, was calculated to be
more than 85% for the buildings on the south side of
Wako campus, namely, the Cooperation Center building of the Advanced Device Laboratory, Chemistry andMaterial Physics building, and Nanoscience Joint Laboratory building.
Reference

1) K. Ikegami et al., RIKEN Accel. Prog. Rep. 34, 349(2001).

200000180000160000Liquid Helium (L)140000120000Surface Chemistry Laboratory
Molecular Characteriza�on Team
Advanced Device Laboratory
Magne�c Materials Laboratory

Other laboratories
Quantum Func�onal System Research GroupRadioac�ve Isotope Physics Laboratory
Surface and Interface Science Laboratory
Condensed Molecular Materials Laboratory
Low Temperature Physics Laboratory
Emergent Phenomena Measurement Research Team
Exploratory Materials Team

100000
80000
60000
40000
20000
0

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
Fiscal Year

Fig. 1. Volumes of liquid helium supplied to the various laboratories for each fiscal year from 2001 to 2018.

∗1∗2

RIKEN Nishina Center
Nippon Air Conditioning Service K.K.

- 221 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

Operation of the BigRIPS cryogenic plant
K. Kusaka,∗1 M. Ohtake,∗1 K. Yoshida,∗1 M. Ohshima,∗2 A. Mikami,∗2 H. Hazama,∗2 H. Miura,∗2 H. Shiraki,∗2
H. Hirai,∗2 M. Haneda,∗2 K. Kimura,∗2 and M. Nagano∗2
We performed two continuous operations of the BigRIPS cryogenic plant in 2019. The first operation period was from March 1 to June 24, and the second wasfrom October 23 to December 11. The total operation
time of the compressor unit was 72,222 h.
During these continuous operations, we encountered
two significant incidents. One incident was the failureof the compressor unit in June. We first noticed an unusual noise that was produced by the main motor of thecompressor unit. Although the noise level gradually increased daily, we maintained the continuous operation
while monitoring the vibrations of the main compressor
and the motor unit. However, the compressor unit suddenly stopped on June 13. Though no interlock alarm
event was recorded, we consider that the reason was theover current of the main motor unit because a sudden increase of the main motor current from 29.9 A to 32.6 A
was recorded in the control system. We could restart thecompressor unit and maintain the continuous operation
till the end of the beam time.
The main motor unit was disassembled on site to investigate the origin of the unusual vibrations. In a bearing
unit on the coupling side, damage was found on a surface
of its inner ring and the bearing balls (Fig. 1). We also
found that the size of the housing for the damaged bearing unit was 5 µm larger than its dimension standard(+0–25 µm. The motor unit was reassembled with new
bearing units, and the housing was re-manufactured witha tolerance of +0.0 µm. After the regular maintenanceof the whole compressor unit, a test operation was successfully performed, and no unusual noise was producedin the second operation period.
Figure 2 shows the vibration acceleration in the vertical and horizontal directions as a function of the total
operation time. Two rapid increases of the vibration acceleration at operation times of 59,000 h and 71,000 h
indicate the damage of the bearing unit occurred in Dec.
20161) and in June 2019. The vibration acceleration re-Fig. 1. Damaged bearing unit, disassembled from the coupling side of the motor unit.
∗1∗2

RIKEN Nishina Center
Nippon Air Conditioning Services Co., Ltd.

Fig. 2. Vibration acceleration of the compressor unit. Two
operation periods are indicated by arrows.

mained less than 8 m/s2 in the second operation period.
The other incident consisted of the failures of the first
expansion turbine T1 in the refrigerator. The T1 turbine
did not start rotation in the starting up of the refrigerator. The starting sequence of the refrigerator unit usually proceeds automatically as follows. The purge line
valve opens for 30 s so that room-temperature heliumgas flows into the gas-bearing cartridge of the expansion turbines T1 and T2. Subsequently the control valve
CV3130 in the turbine inlet line gradually opens, andthe inflow of the cold helium gas starts the rotation ofT1 and T2 simultaneously. The opening of CV3130 increases up to 50% and the rotation speeds of T1 andT2 turbine increase beyond 3000 rps depending on thetemperature of the inlet helium gas.
The first failure of T1 turbine occurred on June 13,
when a sudden stop of the compressor caused refrigerator trip. After having the compressor unit restarted, we
restarted the refrigerator operation. After the turbine
trip caused by the low-temperature interlock of the inlet
helium gas during the start up, T1 did not start rotationin the automatic starting sequence. We somehow started
the refrigerator without the purging process and could
proceed with the beam time till June 19. We stopped therefrigerator in the usual manner and visually checked T1
and T2 in the summer maintenance. Although no visualabnormality was found in the maintenance, the same failure occurred in the test operation on September 25. T1
did not work during start up.
Both turbine cartridges were sent to its manufacturer
Linde and were disassembled. While T2 was not damaged, the gas bearing of T1 had problems. Scratches
and particles were found on the lower axial bearing. After replacing the lower axial bearing with a new one andpolishing the shaft, T1 turbine cartridge was reassembled. The repaired turbines were remounted on October
24, and the refrigerator successfully started on October
25. The origin of the scratches is under investigation.
Reference

1) K. Kusaka et al., RIKEN Accel. Prog. Rep. 50, 285 (2017).

- 222 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

Radiation safety management at RIBF
K. Tanaka,∗1 Y. Uwamino,∗1 H. Sakamoto,∗1 R. Hirunuma-Higurashi,∗1 H. Mukai,∗2 A. Akashio,∗1
T. Okayasu,∗1 R. Suzuki,∗3 M. Takekoshi,∗3 Y. Yamauchi,∗3 K. Igarashi,∗1 S. Iizuka,∗1 N. Usudate,∗1 andY. Shioda∗1

∗1
∗2
∗3

1000

RRC roof
IRC roof
BigRIPS roof

Sv/y

100

10

1
2000

2005

2010
year

2015

2020

Fig. 1. Radiation dose at the boundary of the radiationcontrolled area.

10

Dose rate (Sv/h)

The results of radiation monitoring at RIBF, performed between the border of the facility and theradiation-controlled area, are reported. The residual
doses along the accelerator setups are also presented.
In 2019, a 238 U beam of about 345 MeV/nucleon
was provided at an intensity of 70 particle nA in
November and December. A 78 Kr beam of about
345 MeV/nucleon of 300 particle nA was used in
March and April. Subsequently, 128 Xe beam of about
345 MeV/nucleon of 80 particle nA was used in May
and June.
The dose rates at the boundary of the radiationcontrolled area were monitored. Neutron and γ-ray
monitors were used at three locations roofs of the RRC,
IRC, and BigRIPS. Figure 1 shows the annual neutron
dose at these positions. In 2019, even the highest annual dose of 60 µSv/y at the IRC roof was lower thanthe legal limit of 5.2 mSv/y.
The dose rates at the site boundary, where the legal
limit is 1 mSv/y, were monitored. Neutron and γ-ray
monitors were used, and the annual dose in 2019 was
found to be lower than the detection limit after background correction. The detection limit of the neutron
monitor is 2 µSv/y and that of the γ-ray monitor is
8 µSv/y. Therefore, it was inferred that the annual
dose at the boundary was less than 10 µSv/y, which isconsiderably lower than the legal limit.
The residual radioactivity at the deflectors of the cyclotrons was measured just before maintenance work.
The residual dose depends on factors such as thebeam intensity, accelerator operation time, and cooling time. The dose rates from 1986 are shown in Fig. 2.
The dose rates for FRC, IRC, and SRC are shownfor the years scince 2006, when the RIBF operation
started. For AVF, the dose rate increased in 2006 because the radioisotope production was started and thebeam intensity increased.
The residual radioactivity along the beam lines wasmeasured after almost every experiment. Figure 3
shows the locations of measurement points where highresidual doses were observed. Table 1 lists the dose
rates, beam conditions, and cooling time at the measurement points. The maximum dose was 46 mSv/h
at point 23, which is in the vicinity of the beam dumpof BigRIPS.
The radioactivity in the closed cooling system at BigRIPS was measured. The water for the F0 target, theexit beam dump, and the side-wall dump were sampled
RIKEN Nishina Center
Japan Environment Research Corporation
Daiwa Atomic Engineering Corporation- 223 -

10

10

10

10

5

4

3

AVF
RRC
IRC
SRC
FRC

2

1

1990

1995

2000

2005

Year

2010

2015

2020

Fig. 2. Dose rates of residual radioactivity at the deflectorsof 5 cyclotrons.

in June. The water in the closed cooling systems for
the F0 target was not replaced in 2019. 1300 L ofwater for the exit beam dump was replaced in April
2018, following which 200 L and 130 L of water was
supplied in March and October 2019, respectively. For
the side-wall beam dump, all of the water was replacedin July 2018. The results are listed in Table 2. A liquid
scintillation counter (LSC-7400, Hitachi Co. Ltd.) wasused for low-energy γ ray of 18 keV from H-3 nuclide.
A Ge detector (GC2019, Canbbera Co. Ltd.) was also
used for γ rays emitted from other radionuclides. The
radionuclides, except for H-3, were already filtered byan ion exchange resin in the closed cooling systems.
Although the overall value of contamination was less

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

than the legal limit for drain water, as summarized inTable 2, the water from the closed cooling system will
be dumped into the drain tank before the next operation to prevent contamination in the room in the caseof a water leakage.
The E-learning module, which can be accessed anytime and from anywhere (even from outside RIKEN),
has been used for re-training the radiation workers at
RIBF. About 670 radiation workers have completed
the training in 2019.
As described above, radiation management to comply with lows and to keep the radiation level as low as
possible has been conducted successfully.

Table 1. Dose rates measured at beam lines in 2019.
Points 1–24 indicate the locations where measurements
were taken as shown in Fig. 3.

Point

Dose
Cooling
Date Particle Energy Intensity time
rate (M/D)(MeV/u) (pnA)(μSv/h)
(h)

1
2

300
240

12/27
12/27

O-18
O-18

6.0
6.0

1000
1000

50
50

3

100

12/27

O-18

6.0

1000

50

4

800

12/27

O-18

6.0

1000

50

5

90

7/29

α

7.25

5000

1014

6

400

7/29

V-51

6.0

1000

276

7

120

7/29

V-51

6.0

1000

276

8

120

12/27

U-238

10.75

2629

497

9

95

7/29

V-51

6.0

1000

291

10

110

7/29

N-14

135

142

355

11

2600

6/26

Xe-124

50

370

163

12

2800

12/18

U-238

50

508

286

13

150

12/18

U-238

50

508

286

14

315

12/18

U-238

345

94

284

15

33500

6/26

Xe-124

345

148

161

16

280

12/18

U-238

345

94

284

17

150

6/26

Xe-124

345

148

161

18

1100

6/26

Xe-124

345

148

161

19

250

6/26

Xe-124

345

148

161

20

790

6/26

Xe-124

345

148

161

21

1860

6/26

Xe-124

345

148

161

22

2800

6/26

Xe-124

345

148

161

23

46000

6/26

Xe-124

345

148

161

24

415

12/18

U-238

345

94

284

Fig. 3. Layout of the beam lines at RIBF. The measurement locations listed in Table 1 are indicated.
Table 2. Concentrations of radionuclide in the cooling water at BigRIPS, the allowable legal limits for drain water, and the ratios of concentration to the allowable
limit.

Cooling Nuclide
water
H-3
BigRIPS Mn-54
F0 target
H-3
Be-7
BigRIPS Mn-54
Co-56
exit
Co-57
beam
Co-58
dump
Co-60
H-3
Be-7
BigRIPS Mn-54
side-wall Co-57
beam
Co-58
dump
Co-60
1) read as 3.9× 10-4

- 224 -

Concentration[a] Limit[b] Ratio to(Bq/cm3)(Bq/cm3) limit [a/b]60
5.3e-23.2
1.0
3.9e-43.9e-41)summationon
5.3e-27.6
60
1.3e-11.4e-230
4.5e-45.1e-31
5.1e-32.1e-30.3
6.9e-35.1e-34
1.3e-31.3e-21
1.3e-22.2e-30.2
1.1e-2summationon
1.7e-18.4
60
1.4e-18.5e-330
2.8e-41.5e-31
1.5e-32.3e-34
5.6e-41.3e-31
1.3e-31.7e-30.2
8.6e-3summationon
0.15

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

Operation of the Pelletron tandem accelerator
T. Ikeda,∗1 M. Hamagaki,∗1 and H. Sato∗1
Table 2. Approved conditions at the RIKEN Pelletron.
The tandem accelerator (Pelletron 5SDH-2, 1.7 MVmax.) in the Nishina R&D Building, which is managed
Ion
Maximum Energy
Ion
Maximum Energy
by the Detector Team of RNC, is joint-use equipment inH
3.4 MeVB
10.2 MeV
Wako campus. Figure 1 shows the conﬁguration of theHe
5.1 MeVC
12 MeV
beam elements. Two ion sources are employed. One is
Li / Be
6.8 MeVother
0.6 MeV/u
the RF charge-exchange ion source, called Alphatross,* Z : 1 – 83 excluding deuterons
for experiments using He ion beams. The other is the* Maximum intensity: 6.3 x 1012 ions / s (1 pA)
Source of Negative Ions by Cesium Sputtering (SNICS),(b)which is used for experiments with almost all other ions. (a)Thus far, ion species of H, He, Li, B, C, N, O, Si, Ti, Ni,
Cu, and Au have been accelerated at 0.5–1.7 MV.
The accelerator has four beam lines named BLE/Wnn (nn stands for the bending angle). BL-E45 isused for surface modiﬁcation. BL-E15 is reserved forthe analysis of Rutherford backscattering (RBS) spectrometry/elastic recoil detection analysis (ERDA). A
micrometer-sized beam based on glass capillary optics
Fig. 2. (a) Overhaul of the Pelletron accelerator. (b) Awith an end window is available at BL-W30 to irradiateschool principal explaining the accelerator to students.
the biological sample in air or solution.
During the annual reporting period from January 1 to
December 31, 2019, the total machine time (MT) includglass capillaries at BL-W301) (7 days)
ing a machine study was 20 days, where the condition(2) Microbeam (He ion) irradiation for single cells
test of the ion sources is not included. The ion species
at BL-W302) (9 days including 1 day with He/H++
accelerated in 2019 were the light ions H , He andions.)
He2+ with energies ranging from 1.0 to 4.8 MeV and Au(3) RBS/ERDA experiments using carbon ions (0ions with energies of 3 and 9 MeV, as summarized inday)
Table 1. An experiment used both H and He ions on a(4) Educational experiment of proton capture by carday to compare the eﬀects of diﬀerent stopping powers.
bon/boron nucleus for Nishina School (2 days)
The topics (1–6) are listed with the number of days of(5) Development of charged-particle/gamma-ray demachine time.
tector to be used for RIBF experiments (2 days)(6)
Other development using protons (0 day)
(1) Microbeam performance study with H ions using

Fig. 1. Pelletron tandem accelerator and beamlines in the
Nishina R&D Building.
Table 1. Beam conditions and experiments conducted in thetandem accelerator. A day for He2+ includes an MT for
H+ .

∗1

Ion

Energy[MeV]

Beam current[pnA]

Experiment1H+

1.0–3.00.001–160

Irradiation

84He+, 2+

3.0–4.8

0.018–200

Irradiation

12

Au 5+

3.0–9.0

0.1

Irradiation

1

RIKEN Nishina Center

Operation
time [days]

In this year, the regulation of the maximum energyof carbon ions was changed, as summarized in Table 2 with other ions. The charge state 12 C6+ is now
available with the full acceleration voltage of 1.7 MV(Ecarbon = 11.9 MeV). The approved maximum energy
was 0.6 MeV/nucleon.
The acceleration tank was overhauled in May for theﬁrst time in 3 years (Fig. 2(a)). No serious deterioration
was found at any essential parts for the operation. The
pellet chains and inner wall of the tank were cleaned to
avoid sudden voltage drops. In August, the experimentof the Nishina School was performed. 1- and 2-MeV
protons were provided for the nuclear resonance reactionof 12 C(p, γ)13 N, the reaction energies of which are 0.457
and 1.699 MeV, respectively. The energy spectra of theγ rays from the carbon and boron targets were obtained.
Some known and unknown γ-ray peaks were discussed
by the student participants.
References

1) T. Ikeda et al., Nucl. Instrum. Methods Phys. Res. B 470,
42 (2020).
2) T. Ikeda et al., in this report.

- 225 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 53

Fee-based activities operated by the Industrial Application ResearchTeam
A. Yoshida,∗1 T. Kambara,∗1 H. Haba,∗1 and D. Mori∗1
The fee-based activities operated by the Industrial
Application Research Team in 2019, which are the utilization of heavy-ion beams in the industry and the
distribution of radioisotopes, are summarized below.
RIKEN Nishina Center allows the use of the AVF
cyclotron, RILAC, and RIKEN Ring Cyclotron (RRC)
by private companies in Japan for a fee.1) At present,
the main users are semiconductor companies that irradiate space-use semiconductor devices with Ar, Kr, or
Xe ions from the RRC to simulate single-event eﬀects
due to the heavy-ion components of cosmic radiation.
Proposals for beam utilization are reviewed by a program advisory committee dedicated to industrial use(InPAC). In July 2019, InPAC held its 9th meeting,where it reviewed and approved two proposals. No
fee-based beamtimes were executed in 2019.
Since 2007, RIKEN has distributed radioisotopes(RIs) to users in Japan for a fee in collaboration with
the Japan Radioisotope Association2) (JRIA). The nuclides are 65 Zn (T1/2 = 244 days), 109 Cd (T1/2 = 463
days), 88 Y (T1/2 = 107 days), 85 Sr (T1/2 = 65 days),and 67 Cu (T1/2 = 61.8 hours) produced by the Nuclear
Chemistry Research Team (formerly RI ApplicationsTeam) at the AVF cyclotron. According to a material transfer agreement (MTA) drawn between JRIA
and RIKEN, JRIA mediates the transaction of the RIs
and distributes them to users. 65 Zn and 109 Cd are delivered approximately two weeks after the acceptanceof an order. 85 Sr, 88 Y, and 67 Cu, which have shorthalf-lives, are not stocked like 65 Zn and 109 Cd but are
produced in a scheduled beamtime after an order is
accepted. Therefore, they are delivered two months ormore after an order. Details can be found on the online
ordering system J-RAM3) of JRIA.
In 2019, we delivered no 109 Cd, two shipments of65
Zn with a total activity of 6.7 MBq, two of 88 Y witha total activity of 2 MBq, and one of 67 Cu with anactivity of 5 MBq. The ﬁnal recipients of the RIs were
two universities, one research institute, and one medical research center.
Figure 1 shows the yearly trends in the number oforders and the amounts of distributed RIs. Comparedwith 2018, the amounts of distributed 65 Zn and 85 Sr
decreased and that of distributed 88 Y remained thesame. The shipment of 67 Cu is the ﬁrst since westarted its delivery in August 2018.
In the general trend, the demand for long-lived RIs
has drastically decreased, whereas that for short-lived
RIs is increasing.
∗1

RIKEN Nishina Center- 226 -

Fig. 1. Number of orders (upper) and amount (lower) of
the RIs distributed yearly from 2007 to 2019. The distribution of 88 Y started in 2010, that of 85 Sr in 2015,
and that of 67 Cu in 2018.

References

1) http://ribf.riken.jp/sisetu-kyoyo/ (Japanese).
2) http://www.jrias.or.jp/ (Japanese),
http://www.jrias.or.jp/e/ (English).
3) https://j-ram.org/ (Japanese).

V. EVENTS

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 53

Nishina School 2019
H. Ishiyama,∗1 T. Motobayashi,∗1 and H. Ueno∗2
Nishina School aims at introducing nuclear physics research to Asian university students who are choosing
their future ﬁeld of study. In 2019, the 13th Nishina
School was held from July 30 to August 9. This period was made slightly later than usual to make it easier for Japanese students to participate after their termend examinations. Students and supervisors from Peking
University (PKU), the University of Hong Kong (HKU),
Seoul National University, Rikkyo University, and Tohoku University joined Nishina School this year. Highschool students from Philips Exeter Academy, USA,
along with their teacher, participated in most of the
School programs. Figure 1 shows all 22 students andSchool staﬀ members.
The School began with self-introductions of the students. The ﬁrst week was dedicated mostly to lectures
and training on a few subjects related to a nuclear reaction experiment that was performed in the second weekof the School. The lectures were on a few basic topics forresearch, including overviews of nuclear physics and nuclear astrophysics, as well as methods of radiation measurements. Another lecture was dedicated to radiation
safety. The training subjects were electronic-pulse propagation and radiation detection. The training covered
the detectors, electronics, and data acquisition system
to be used in the experiment in the following week.
The program in the second week focused on a reaction
experiment using proton beams from the Pelletron accelerator at RIKEN Nishina Center. The students weredivided into six groups, which oversaw six diﬀerent typesof measurements. They started to design the experimentby evaluating the feasibility of measurements (i.e., estimation of γ-ray yields, etc.), following which they set thedetectors around the reaction target and determined theconditions of beam exposure based on their considerations. After the experiment, they analyzed the experimental data obtained and ﬁnally made presentations on

Fig. 1. Participants of Nishina School 2019.
∗1∗2

School Master
Chair, Nishina School Steering Committee

Fig. 2. Photograph of the experimental apparatus. The 12 C
or BN target in the vacuum pipe at the center of photograph was irradiated with proton beams from the Pelletron accelerator. The NaI detector at upper side of thephotograph detected γ-rays generated by the reactions.

Fig. 3. Example of the γ-ray spectra obtained for the “inbeam” measurement of the 12 C(p, γ)13 N reaction with a
2-MeV proton beam.

their results. They studied the low-energy 12 C(p, γ)13 N
or 10 B(p, α)7 Be reaction, which are related to nucleosynthesis in stars.
Figure 2 shows the experimental apparatus. Proton
beams with an energy of 1 or 2 MeV bombarded a carbon or boron nitride target, which stopped the protons toprovide a so-called thick target yield of those reactions.
Two methods were employed to determine the resonanceyield: the detection of “in-beam” γ-rays from 13 N or 7 Be
excited states and the detection of 511-keV γ-rays fromthe β + decay of 13 N or 7 Be activities, which is known as
the “activation” technique. Figure 3 shows an example ofthe obtained γ-ray spectrum for the “in-beam” measurement of the 12 C(p, γ)13 N reaction. Two distinct peaks ofrelevance in the experiment are clearly observed. The six
teams could ﬁnally extract the reaction cross sections.
We thank all the staﬀ members of the Nishina Center
who participated and helped in Nishina School 2019.
- 227 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 53

Creation of superheavy elements highlighted at the closing ceremony of
IYPT 2019†
H. En’yo,∗1
The year, 2019 was the International Year of the Periodic Table (IYPT). It marked the celebration of the150th anniversary of Mendeleev’s periodic table and thecompletion of the 7th row of the table. The opening
ceremony took place on January 29th at the UNESCO
HQ in Paris, and the closing ceremony took place on
December 5th at the Tokyo Prince Hotel. The closing
ceremony was hosted by the Chemical Society of Japan,
Science Council of Japan, and RIKEN on behalf of UNESCO, IUPAC, and IUPAP.
The closing ceremony included an impressive list of
exhibitions and sessions; it started with an opening session, followed by sessions titled “Introduction of IYPT
activities” and “Discoveries and Creation of elements,”
and ended with a session titled “Periodic Table for Next
Generations.” The event also had musical performances,including one by an orchestra comprised of Japanesechemists. The entire program was recorded and can beviewed on the web page of IYPT of Japan.1)
An important session for Nishina Center was the “Creation of Superheavy Elements,” which started with the
piano fantasy “Nihonium” played by a high school student Honoka Motai. Miss Motai is so devoted to theperiodic table that the discovery of nihonium inspired
her to compose the music she performed. Her beautiful
music was accompanied by a screen showing the landscape of Nihonium Avenue stretching from Wako City
Station to RIKEN.2) This avenue is a “walk of fame”
of about 15 min for the 118 elements from hydrogento oganesson, which are displayed in paving stones andlead to the entrance of RIKEN, where a large monument
dedicated to nihonium is installed.

After the piano performance, celebrated speeches were
given with institutional introductory movies. This included Victor Matveev for the Joint Institute for Nuclear
Research, Karlheinz Langanke for GSI Helmholtzzentrum für Schwerionenforschung, Roderick Clark for
Lawrence Berkeley National Laboratory, Mark Stoyer
for Lawrence Livermore National Laboratory, Krzysztof
Rykaczewski for Oak Ridge National Laboratory, Kosuke Morita for RIKEN Nishina Center, and a final speech given by Yuri Oganessian representing all
the discoverers. Lastly, the boards of 15 superheavy
elements from Rf (Z = 104) to Og (Z = 118)
are shown in line by M. Itkis (JINR), V. Matveev(JINR), R. Clark (LBNL), A. Yakushev (GSI), C. Duellmann (GSI, JGUM), M. Block (GSI, JGUM), K. Langanke (GSI), D. Ackermann (GANIL), J. Khuyagbaatar(GSI), M. Honoka (Tokyo Gakugei University SeniorHigh School) with K. Morimoto (RIKEN), S. Dmitriev(FLNR, JINR), V. Utyonkov (FLNR, JINR), M. Stoyer(LLNL), K. Rykaczewski (ORNL), and A. Karpov(FLNR, JINR), respectively.
These scientists had participated in both this ceremony and the 4th International Symposium on Superheavy Elements (SHE2019), held from 1–5 December at
Hakone. H. Haba (RIKEN) and K. Morita (Kyushu-U,
RIKEN) jointly chaired the symposium.
References

1) https://iypt.jp/ .
2) The video was created by N. Miya-uchi, RIKEN Nishina
Center, and can be obtained upon request.

Fig. 1. The boards of 15 superheavy elements from Rf to Og displayed by discoverers.
†∗1

Condensed from the article in Nucl. Phys. News 30, 1 (2020)
RIKEN Nishina Center- 228 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 53

The 3rd “Hodan-kai” meeting for the future of exotic nuclear physics
W. Horiuchi,∗1,∗2 Y. Ichikawa,∗3,∗4 K. Sekizawa,∗5 and D. Suzuki∗3 for the “Hodan-kai” meeting organizers
The third “Hodan-kai” meeting by young researchers
was held from February 19 to 21, 2020 at the Integrated
Innovation Building in Kobe campus of RIKEN, whichis the same venue as for the previous Hodan-kai meetings. This Hodan-kai was the third in the meeting
series organized by RIBF Theory Forum and RIKEN
Nishina Center, and supported by RIKEN iTHEMS
and JICFuS. The style of Hodan-kai is diﬀerent fromthat of an ordinary workshop in which recent researchworks are presented by the respective research groups.
This meeting aims to facilitate the exchange of new
ideas among young researchers, including unmatured
ideas and dreams that are not feasible at present.
Given the spirit of the meeting, the presentation ﬁles
are disclosed to the public. Furthermore, the venue islocated in a rather isolated place, which enables participants to concentrate on physics discussions. The
meeting always exceeds the scheduled time owing topassionate discussions among the participants.
The ﬁrst Hodan-kai was held from July 21 to August
2, 2017, and focused mainly on the latest theoretical research on nuclear physics. The number of participants
was 49 with 23 presentations. The second meeting washeld from February 18 to 20, 2019 and had 42 participants. While limiting the number of presentations to
25, the topic was extended: 6 presentations were madeby theoretical nuclear physicists, 7 presentations by
experimental nuclear physicists, and 12 presentations
by researchers in other ﬁelds that may closely be re-Fig. 2. Photograph of a panel discussion.

lated to nuclear physics. The program and summaryof the ﬁrst and second Hodan-kai were shared on theirrespective websites.1,2)
In the third Hodan-kai, we had 43 participants and17 presentations by young researchers including 6 and
7 presentations by theoretical and experimental nuclear physicists, respectively, and 4 presentations byresearchers in other ﬁelds. In addition to these talks
given in the regular Hodan-kai style, we newly organized two “panel discussion” sections to facilitate interaction among the participants. In the panel discussions, introductory talks on “New textbook for nuclear
physics” and “What is cooling?” were given by theorganizers, and 5–7 short talks were given by invited
panelists. Though, as always, these exciting discussions easily exceeded the scheduled time, the meeting
ended sucessfully while keeping the spirit of Hodan-kai.
The full program and summary of the third Hodan-kai
can be found on its website.3) Figures 1 and 2 show
some snapshots of the 3rd Hodan-kai. Attracting more
students to this meeting is one of the key ingredientsfor the success of “Hodan-kai.” We plan to hold thenext Hodan-kai in February 2021 and look forward to
having more participants.
References

Fig. 1. Group photograph of the 3rd “Hodan-kai” meeting.
∗1
∗2
∗3
∗4
∗5

Department of Physics, Hokkaido University
RIBF Theory ForumRIKEN Nishina Center
Department of Physics, Kyushu University
Center for Transdisciplinary Research, Institute for Research Promotion, Niigata University- 229 -

1) 1st Hodan-kai:
2509/ .
2) 2nd Hodan-kai:
2864/ .
3) 3rd Hodan-kai:
3157/ .

https://indico2.riken.jp/event/
https://indico2.riken.jp/event/
https://indico2.riken.jp/event/Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 53

SHE2019—The 4th International Symposium on Superheavy Elements
H. Haba on behalf of the SHE2019 Local Organizing Committee∗1
The 4th International Symposium on Superheavy
Elements (SHE2019) was held on December 1–5, 2019
at The Prince Hakone Lake Ashinoko in Hakone,
Japan. Hakone is close to Tokyo, situated at the footof Mount Fuji, and one of the most popular travel
destinations among Japanese and foreign tourists.
SHE2019 followed the previous symposiums at Texas
A&M University, USA in 2013 and 2015 and Kazimierz
Dolny, Poland in 2017. This symposium was jointly organized by the RIKEN Nishina Center, Research Center for Superheavy Elements, Kyushu University, andAdvanced Science Research Center, Japan Atomic Energy Agency. It had 130 registrants from 16 countries.
There were 2 plenary, 33 invited, and 27 oral talks, aswell as 14 poster presentations.
SHE2019 covered all theoretical and experimental
aspects of superheavy nuclei and atoms. SHE2019
started with two plenary talks titled “SHE2019 Symposium: experimental challenges” by Y. Oganessianand “Superheavy elements: theoretical challenge” by
W. Nazarewicz of Michigan State University, USA on
the evening of December 1. From the morning of December 2 till the evening of December 4, the following scientific sessions were conducted: 1) Reaction of
Synthesis of the Heaviest and Neutron-rich Nuclei; 2)
Status and Short-term Plans at SHE Facilities; 3) Nu-

cleosynthesis of SHE and Search in Nature; 4) Properties and Structure of the SHN; and Decays, 5) Heavy
Atoms and Chemistry of SHE; 6) New Approaches and
Setups; and 7) New Facilities, Setups, and Instrumentations. On the evening of December 2–4, Young Scientists sessions were held to give young scientists as
many opportunities for oral presentation as possible.
The excursion of SHE2019 was conducted in theafternoon on December 4. The participants visited
Hakone Lake to enjoy the scenery, Hakone Sekisho(checkpoint) to experience the history, and Hakone
Shrine to explore the local culture and religion.
The year 2019 marked the 150th anniversary of the
discovery of the periodicity of chemical elements by
Dmitrij Ivanovich Mendelejev. Thus, the United Nations and UNESCO proclaimed 2019 as the “International Year of the Periodic Table of Chemical Elements(IYPT2019).” The Closing Ceremony of IYPT washeld at The Tokyo Prince Hotel in Tokyo, Japan on December 5th, immediately after SHE2019. Most of the
SHE2019 participants joined the Closing Ceremony of
IYPT and celebrated the discoveries of elements 113,
115, 117, and 118—nihonium (Nh), moscovium (Mc),tennessine (Ts), and oganesson (Og), respectively—
and the completion of the 7th period of the periodic
table.

Fig. 1. Conference photo taken at a garden of The Prince Hakone Lake Ashinoko on December 4, 2019c(⃝Hideto
En’yo).
∗1

RIKEN Nishina Center- 230 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 53

RIKEN Symposium “Trends in ion-beam breeding over the last two
decades and future research”
T. Abe,∗1 Y. Hayashi,∗1 H. Ichida,∗1 K. Ishii,∗1 R. Morita,∗1 K. Tsuneizumi,∗1 M. Izumi,∗1 Y. Shirakawa,∗1
S. Ohbu,∗1 M. Yamada,∗1 H. Abe,∗1 K. Ichinose,∗1 and N. Asakawa∗1
The RIKEN Symposium on “Trends in ion-beam
breeding over the last two decades and future research”
was held on 23–24 Jan. 2020 at the RIKEN Wako Campus. It was the 9th RARF/RIBF User’s Meeting on
Biology, which is held once every two years. The Beam
Mutagenesis Group promotes various life-science applications of ion beams from the RI Beam Factory. In
particular, this group develops new techniques to breed
plants and microbes with the use of heavy-ion irradiation. We started collaborations with ﬂower companies
and public agricultural experimental stations in 1996
to investigate the potential uses of heavy-ion beams inapplied plant breeding. As a result, two new ﬂower varieties were obtained from irradiated samples in 1998.
The former is a dahlia having large ﬂowers and a novel
color, and it has been sold in Hiroshima City since theautumn of 2001.1) The latter is a verbena, which issterile, generating no seeds; produces ﬂowers with aprolonged lifespan; and has been marketed since thespring of 2002.2) We formed a consortium for ion-beam
breeding. In 2019, it consisted of 184 domestic and20 overseas user institutions. We have already produced 34 new plant varieties. This meeting was ﬁrst
convened in Jan. 2003 to spread ion-beam breeding
technology, and it consisted of practical research, biology, and special lectures. Practical research is classiﬁed into research on ﬂowers, food crops, microbes, andenvironmental-improving plants such as trees and moss
depending on the irradiation samples. Figure 1 shows
the change in the numbers of participants categorized
by their specialization. The number of ﬂower breeders
has decreased since the early meetings. We found thations with higher LETs, such as Fe, are eﬀective for the
mutation breeding of microbes.3) Two new yeast strains
created in 2010 are currently used by over 20 breweries
to produce high-quality sake in Japan.4) The numberof microbe breeders has increased since 2011. NEXTand SIP programs were started from 2010 and 2014,
respectively. We have been investigating the eﬀects of
LETs ranging from 23 to 640 keV/µm on mutation induction. The highest mutation rate was observed at an
LET of 30 keV/µm (LETmax) in Arabidopsis thaliana 5)
and rice.6) The majority of mutations caused by LETmax irradiation were small deletions that were suﬃcient to disrupt a single gene.7) We have been using
high- throughput DNA sequencing technologies to analyze gene mutations. An increasing number of biologists
have shown that mutants induced by LETmax irradiation have become more useful and important in modern∗1

RIKEN Nishina CenterNo. of participants
130

192

190

Year 2003
I
held
2007

2009
I
2013

2015
I
2019

Biology
Tree
MicrobeFood
crop

FlowerFig. 1. Changes in the specializations of symposium participants from 2003 to 2019.

genetic studies, enabling the discovery of genes.8,9)The symposium began with the history over the lasttwo decades of biology and practical research on ﬂowers
and food crops. In a special issue, Dr. Kang, who belongs to ARTI and KAERI and is the President of the
Korean Society of Breeding Science, introduced “Current status and future prospect of mutation breeding
research in Korea.” The next session was on the results of breeding microbe such as Tricholoma matsutake, baker’s yeast, and microalgae. Finally, we discussed avenues for research on biology and ion-beam
breeding in the next decade. The targets of heavyion breeding have extended from ﬂowers to crops suchas grains and beans, which will contribute to solving
the global problems of food supply and environmental
stress. The next meeting will be held in Jan. 2022.
References

1) M. Hamatani et al., RIKEN Accel. Prog. Rep. 34, 169(2001).
2) T. Kanaya et al., Plant Biotech. 25, 91 (2008).
3) H. Ichida et al., Mut Res. 639, 101 (2008).
4) M. Yokobori et al., RIKEN Accel. Prog. Rep. 45, xxiii(2012).
5) Y. Kazama et al., Plant Biotech. 25, 113 (2008).
6) Y. Hayashii et al., RIKEN Accel. Prog. Rep. 50, 27 (2017).
7) Y. Kazama et al., BMC Plant Biol. 11, 161 (2011).
8) Y. Koide et al., Proc. Natl. Acad. Sci. USA 115, E1955(2018).
9) R. Morita et al., Mol. Breed. 39, 135 (2019).

- 231 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 53

RIKEN Open Day 2019
H. Haba∗1 and K. Takahashi∗1
RIKEN Open Day, on which many laboratories
showcase their research activities and attractive experimental devices to the public, was held in the RIKEN
Wako campus on April 20, 2019. In the Nishina Center, 17 research groups comprising more than 200 researchers participated in the event, as listed in Table 1.
The cover page of the leaflet that introduced the exhibition content in the Nishina Center is shown in Fig. 1.
The radiation controlled area in the RIBF building was
opened to the public to display the world’s largest superconducting cyclotron SRC, the in-flight RI separator BigRIPS, and other powerful experimental devices,along with the exhibition laboratories.
The year 2019 marked the 150th anniversary of the
discovery of the periodicity of chemical elements by
Dimitry Mendeleev. Thus, the United Nations and
UNESCO proclaimed 2019 as the “International Yearof the Periodic Table of Chemical Elements.” Dr. Kosuke Morita, the director of the Superheavy Element
Research Group, gave a scientific lecture titled “Insearch of further new elements” at the Suzuki Umetaro
Hall. He presented the discovery of element 113, nihonium, and the research plan for the next new element,element 119, at RIBF. The weather on the open day
was very pleasant. A total of 8,253 visitors came to
the RIKEN Wako Campus. Among them, 3,013 visited RIBF.

Fig. 1. Cover of the leaflet provided by the Nishina Center
for RIKEN Open Day 2019.

Table 1. List of the Nishina Center exhibitions on RIKEN Open Day 2019.

Laboratory / Group / Team
Accelerator GroupSLOWRI TeamBigRIPS Team
Rare RI-Ring Team
Spin isospin Laboratory
SAMURAI Team
Nuclear Spectroscopy Laboratory
Radioactive Isotope Physics Laboratory
Nishina Center
Nuclear Chemistry Research TeamIon Beam Breeding TeamSuperheavy Element Research Group
User Liaison GroupSCRIT Team
Radiation Laboratory
Quantum Hadron Physics Laboratory
High Energy Astrophysics Laboratory∗1

Exhibition theme
The World’s Strongest Superconducting Ring Cyclotron
Ion Trap and Ultra-Slow RI Production
Superconducting RI Beam Separator BigRIPS
Precision Mass Measurement in 1 ms
Microscopes for Unstable Nuclei
SAMURAI Magnetic Spectrometer
Tiny Magnets in Materials
Study on Origin of Elements at RIBF
Glass Marble Shooting
Nuclear Chart with LEGO Block
Familiar RI and Useful RI
Creating Amazing Plants
The Discovery of the New Element "Nihonium"
Let's Make Your Nihonium
Handmade Spectrometer
See Radiation with Diffusion Cloud Chamber
Enjoy Spinning a Variety of Tops
Research Activities in the Experimental Hadron Physics
Elementary Particles, Nuclei and the Universe
In Space Now

RIKEN Nishina Center- 232 -

Number of staff
35
4
11
8
13
6
12
9
10
7
6
15
12
7
7
11
13
40

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 53

Outreach activities outside the Wako campus
N. Miyauchi∗1
The year 2019 marks the 150th anniversary of the discovery of Mendeleev’s periodic law. Further, in 2016,
the names of the four elements up to the 118th, including the 113th element nihonium, were finalized, andthe 7th period of the periodic table was completed. To
commemorate these events, the United Nations General
Assembly and UNESCO declared 2019 as the International Year of Periodic Table (IYPT2019). Accordingly,
various events related to the periodic table were held
globally. In Japan, “the Japan Chemical Society, International Year of Periodic Table 2019 Executive Committee” organized special traveling exhibitions at about 20
locations across the country to familiarize people withthe periodic table. The User Liaison Group held workshops at two locations in these traveling exhibitions.
JST Science Agora in Daiba, Tokyo on Nov. 16–
17
The workshop aimed to build a model of the 113th
element, nihonium. The first workshop was held at a
traveling exhibition booth organized by the Executive
Committee of the International Periodic Table at the
Science Agora1) venue on November 16 and 17, 2019(the Science Agora itself was held for three days, from
November 15 to 17). Specifically, we asked participants
to make a three-dimensional nihonium model using smallbeads, which are a children’s toy, and helped them gain
an understanding of the nucleus and how nihonium was
discovered. Although the nucleus is never visible to thenaked eye, the workshop was an attempt to make people
feel the existence of the nucleus by making a model using
the actual number of protons and neutrons.
This time, owing to the limited size of our booth, only
a few participants could be taught by a researcher. As aresult, the total number of participants was only 44 overtwo days. Although the workshop had the disadvantage
of not being able to handle a large number of people,
it was well received because the participants were able
to talk with actual researchers owing to the face-to-faceseating style.
Ehime Prefectural Science Museum on Jan. 18–
19
The next nihonium workshop was held at anothertraveling exhibition booth organized by the Executive
Committee at the Ehime Prefectural Science Museum2)
on January 18 and 19, 2020 (we were invited for two days
to the traveling exhibition that was conducted from December 14, 2019 to January 26, 2020). The workshop
was a great success because Mr. Yoji Hisamatsu (of thisScience Museum), who directed all the traveling exhibitions, took care of us. More than 100 participants made∗1

RIKEN Nishina Center

Fig. 1. Workshop to make a nihonium model using smallbeads.

Fig. 2. Brief lecture on atomic nuclei and nihonium.

their own models of nihonium over the two days of theworkshop.
RIKEN Osaka Campus Open Day 2019
Apart from the above two traveling exhibitions, weparticipated in the open house of RIKEN’s Osaka campus on November 23, 2019. Various RIKEN Centersfrom all over Japan also participated in the event to introduce their research to people in the Osaka area. We
introduced research at the RNC by using a small 3D
nuclear chart produced by a 3D printer, in addition toposter panels. We had a large audience including children. The exhibition was very successful.
References

1) https://www.jst.go.jp/sis/scienceagora/en/reports/
2019/ .
2) http://www.i-kahaku.jp/index.html .

- 233 -

VI. ORGANIZATION AND ACTIVITIESOF RIKEN NISHINA CENTER(Activities, Members, Publications & Presentations)Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

1. Organization
1.1 Organization Chart as of March 31, 2020 （End of FY2019）- 235 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

1.2 Topics in FY2019
Year

Date

Topics in Management

2019

Apr. 1

Newly appointed:
Deputy Director of RIKEN BNL Research Center: David MORRISON

2019

Apr. 1

Newly appointed:
Team Leader of Plant Genome Evolution Research Team: Tomoko ABE

2. Finances
A transition of the RNC budget for the past four years is shown in following graph.
Million Yen

3,500
3,000
2,500
2,000
1,500

3,060

3,199

2016

2017

2,877

2,824

2018

2019

1,000
500
0

3. Staffing
At the start of FY 2019, there were 142 personnel affiliated with RNC and 419 researchers visiting RNC for research purpose. The following
graphs show a breakdown of personnel into six categories as of April 1, 2019, and a transition of the number of each category.

73

Permanent Researcher

28

Contract Researcher
Technical staff

419

Special Postdoctoral Researcher
Junior Research Associate
External researcher

FY2019- 236 -

5

18
18

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

600

External researcher

500

Junior Research Associate

400
Special Postdoctoral
Researcher

300

Technical staff

200

Contract Researcher

100

Permanent Researcher

0

2016

2017

2018

2019

4. Research publication
The number of papers published annually from RNC is shown graphically using the data obtained from Clarivate Analytics’ Web of Science
Documents.

400
Source Documents

350
300
250
200
150
100
50
0

2016

2017

2018

2019

Publication Year
Citation analysis for the past four years
As of April 2020
Year
Indicators
Total number of papers

2016

2017

2018

2019

347

298

286

301

Percentage of papers in top 10%

15.85

16.78

20.63

9.63

Percentage of papers in top 1%

1.44

2.68

4.20

1.00

- 237 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

5. Management
Headed by the RNC Director Hideto En'yo, the RIKEN Nishina Center for Accelerator-Based Science (RNC) consists of:

9 Laboratories
10 Groups with 27 Teams
2 overseas research centers with 3 Groups

as of the end of FY2019. There are also two 'Partner Institutes' which conduct research in the laboratories set up in RNC. RNC is managed
by its Director who takes into consideration the majority decision of the RNC Coordination Committee. The management of RNC is supportedby the following committees:Program Advisory Committee
Safety Review Committee
RIBF Machine Time Committee
Public Relations Committee

There are also committees to support the President of RIKEN and/or the Director of RNC such as:

Nishina Center Advisory Council with three subcommittees:
・RBRC Scientific Review Committee (SRC)・International Advisory Committee for the RIKEN-RAL Muon Facility
・RBRC Management Steering Committee (MSC)

Nishina Center for Accelerator-based Science
Executive Members (as of March 31, 2020)
Hideto EN'YO
Director
Hiroyoshi SAKURAI
Deputy Director (Nuclear Science and Transmutation Research Division)
Osamu KAMIGAITO
Deputy Director (Research Facility Development Division)
Tomoko ABE
Deputy Director (Accelerator Application Division)
Yasushige YANO
Senior Advisor
Tohru MOTOBAYASHI
Senior Advisor
Hideyuki SAKAI
Senior Advisor

RNC Coordination Committee
The following subjects relevant to the RNC management are deliberated under the chairmanship of the RNC Director:






Establishment of the new organization or reorganization in RNC
Personnel management of RNC researchers
Research themes and research budget
Approval of the Partner Institutes
Evaluation of the management of RNC and the response to the recommendations by external evaluation

The RNC Coordination Committee is held monthly.
Members (as of March 31, 2020)
Hideto EN'YO
Director, RNC; Director, Radiation Laboratory
Hiroyoshi SAKURAI
Deputy Director, RNC; Director, Radioactive Isotope Physics Laboratory and Nuclear Transmutation Data ResearchGroup; Team Leader, Muon Date Team
Osamu KAMIGAITO
Deputy Director, RNC; Director, Accelerator Group and High-Intensity Accelerator R&D Group; Team Leader,
Infrastructure Management Team
Tomoko ABE
Deputy Director, RNC; Director, Beam Mutagenesis Group; Team Leader, Ion Beam Breeding Team and Plant
Yasushige YANO
Tohru MOTOBAYASHI
Hideyuki SAKAI
Tomohiro UESAKA
Hideki UENO
Toru TAMAGAWA
Kosuke MORITA
Yuko MOTIZUKI
Hiroki OKUNO

Genome Evolution Research Team

Senior Advisor, RNC
Senior Advisor, RNC
Senior Advisor, RNC
Director, Spin Isospin Laboratory and Research Instruments Group
Director, Nuclear Spectroscopy Laboratory and User Liaison Group; Team Leader, Outreach Team
Director, High Energy Astrophysics Laboratory
Director, Superheavy Element Research Group
Director, Astro-Glaciology Research Group
Deputy Group Director, Accelerator Group; Team Leader, Accelerator R&D Team, Cryogenic Technology Team, andHigh-Power Target R&D Team- 238 -

Ⅵ. RNC ACTIVITIESNobuhisa FUKUNISHI
Masanori WAKASUGIHiromitsu HABA
Tetsuo HATSUDA
Emiko HIYAMA
Masahiko IWASAKI
Kanenobu TANAKA
Koji MORIMOTO
Hideaki OTSU
Toshiyuki SUMIKAMA
Naruhiko SAKAMOTO
Takahide NAKAGAWA
Eiji IKEZAWA
Hironobu ISHIYAMA
Koichi YOSHIDA
Hidetada BABA
Hiromi SATO
Atsushi YOSHIDA
Ken-ichiro YONEDA
Yasuyuki AKIBA
Taku IZUBUCHI
Tsukasa TADA
Yutaka WATANABE
Yasushi WATANABE
Koichi ABE

RIKEN Accel. Prog. Rep. 53

Deputy Group Director, Accelerator Group; Team Leader, Beam Dynamics & Diagnostics Team
Director, Instrumentation Development Group; Team Leader, Rare RI-Ring Team and SCRIT Team
Director, RI Application Research Group; Team Leader, RI Application Team and Superheavy Element Production
Team
Director, Quantum Hadron Physics Laboratory
Director, Strangeness Nuclear Physics Laboratory
Director, Meson Science Laboratory
Director, Safety Management GroupTeam Leader, Superheavy Element Device Development Team
Team Leader, SAMURAI Team and Fast RI Data Team
Team Leader, Slow RI Data Team
Team Leader, Cyclotron Team and High-Gradient Cavity R&D Team
Team Leader, Ion Source Team
Team Leader, RILAC Team
Team Leader, SLOWRI Team
Team Leader, BigRIPS Team
Team Leader, Computing and Network Team
Team Leader, Detector Team
Team Leader, Industrial Application Research Team
Team Leader, RIBF User Liaison TeamGroup Leader, Experimental Group, RIKEN BNL Research Center
Group Leader, Computing Group, RIKEN BNL Research Center
Vice Chief Scientist, Quantum Hadron Physics Laboratory
Deputy Team Leader, Infrastructure Management Team
Deputy Team Leader, RIBF User Liaison Team
Director, Nishina Center and iTHEMS Promotion Office

Program Advisory Committee
The Program Advisory Committee reviews experimental proposals submitted by researchers and reports the approval/disapproval of the
proposals to the RNC Director. The Committee also reports to the RNC Director the available days of operation at RIBF or the Muon
Facility at RAL allocated to researchers. The Committee is divided into three categories according to the research field.


Nuclear Physics Experiments at RIBF (NP-PAC): academic research in nuclear physics
Materials and Life Science Researches at RNC (ML-PAC): academic research in materials science and life science
Industrial Program Advisory Committee (In-PAC): non-academic research

Program Advisory Committee for Nuclear Physics Experiments at RI Beam Factory (NP-PAC)
The 20th NP-PAC was held on December 16−18, 2019 at RIBF.
Members (as of March 31, 2020)
Robert V.F. JANSSENS (Chair)
Dieter ACKERMANN
Nori AOIMaria J.G. BORGE
Robert CHARITY
Augusto O. MACCHIAVELLI
Gabriel MARTINEZ-PINEDO
Iain MOOREDavid J. MORRISSEY
Hitoshi NAKADA
Alexandre OBERTELLITakehiko SAITO
Kimiko SEKIGUCHI
Philip J. WOODS
Andrea VITTURI
Xiaohong ZHOU

University of North Carolina at Chapel Hill
GANIL
Osaka University
Consejo Superior de Investigaciones Científicas
Washington University in St. Louis
Lawrence Berkeley National Laboratory
Technische Universität Darmstadt, GSI Helmholtzzentrum für Schwerionenforschung
University of Jyväskylä
Michigan State University
Chiba University
Technische Universität Darmstadt
RIKEN Cluster for Pioneering Research
Tohoku University
University of Edinburgh
Universita' di Padova
Institute of Modern Physics, CAS

Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)
The 18th and 19th ML-PAC was held on June 28, 2019 and January 24, 2020 at RIBF, respectively.
Members (as of March 31, 2020)
Adrian HILLIER (Chair)
Philippe MENDELS
Zhi QIN
Toshiyuki AZUMA
Ryosuke KADONOISIS, RAL (UK)
Laboratorie de Physique des Solides, Universite Paris (SUD)
Institute of Modern Physics, CAS
RIKEN Cluster for Pioneering ResearchInstitute of Materials Structure Science (KEK)- 239 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Atsushi KAWAMOTO
Shigeyuki KAWANO
Kenya KUBO
Hiroyuki YAMASE
Xu-Guang ZHENG
Robert V.F. JANSSENS

Hokkaido University
The University of Tokyo
International Christian University
Research Center for Functional Materials, NIMS
Saga University
University of North Carolina at Chapel Hill

Industrial Program Advisory Committee (In-PAC)
The 9th In-PAC was held on July 10, 2019 at RNC.

Safety Review Committee
The Safety Review Committee is composed of two sub committees, the Safety Review Committee for Accelerator Experiments and the HotLab Safety Review Committee. These Committees review the safety regarding the usage of radiation generating equipment based on the
proposal submitted to the RNC Director from the spokesperson of the approved experiment.
Safety Review Committee for Accelerator Experiments
Members (as of March 31, 2020)
Hiromi SATO (Chair)
Kouji MORIMOTO
Eiji IKEZAWA
Hiromitsu HABA
Atsushi YOSHIDA
Koichi YOSHIDA
Naoki FUKUDA
Naruhiko SAKAMOTO
Daisuke SUZUKI
Masaki SASANO
Yuichi ICHIKAWA

Team Leader, Detector Team
Team Leader, Superheavy Element Device Development Team
Team Leader, RILAC Team
Team Leader, RI Application Team
Team Leader, Industrial Cooperation Team
Team Leader, BigRIPS TeamTechnical Scientis, BigRIPS Team
Team Leader, Cyclotron Team
Research Scientist, Radioactive Isotope Physics Laboratory
Senior Research Scientist, Spin Isospin Laboratory
Senior Research Scientist, Nuclear Spectroscopy Laboratory

External members
Shinichiro MICHIMASA
Hidetoshi YAMAGUCHI
Yutaka WATANABE

Assistant Professor, Center for Nuclear Study, University of Tokyo
Lecturer, Center for Nuclear Study, University of Tokyo
Associate Professor, High Energy Accelerator Research Organization, KEK

Ex officio members
Kanenobu TANAKA
Hisao SAKAMOTO

Director, Safety Management Group
Technical Scientist, Safety Management Group

Hot-Lab Safety Review Committee
Members (as of March 31, 2020)
Kazuya TAKAHASHI (Chair)
Kanenobu TANAKA
Hisao SAKAMOTO
Hiroki MUKAI
Eriko HIGURASHI
Hiromitsu HABA
Tetsuya OHNISHI

Senior Research Scientist, Nuclear Chemistry Research Team
Director, Safety Management Group
Technical Scientist, Safety Management Group
Technical Staff I, Safety Management Group
Technical Scientist, Safety Management GroupTeam Leader, RI Application Team
Senior Research Scientist, SCRIT TeamRIBF Machine Time Committee
Upon request of the RNC Director, the RIBF Machine Time Committee deliberates on the machine time schedule of RIBF and reports theresults to the Director.
Members (as of March 31, 2020)
Hideki UENO (Chair)
Osamu KAMIGAITO
Masanori WAKASUGITomohiro UESAKA
Nobuhisa FUKUNISHI
Hiroki OKUNO
Hiroyoshi SAKURAI
Tomoko ABE

Director, User Liaison Group and Nuclear Spectroscopy Laboratory
Director, Accelerator Group
Director, Instrumentation Development Group
Director, Research Instruments Group and Spin Isospin Laboratory
Deputy Group Director, Accelerator Group
Deputy Group Director, Accelerator Group
Director, Radioactive Isotope Physics Laboratory
Director, Beam Mutagenesis Group- 240 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Hiromitsu HABA
Kanenobu TANAKA
Ken-ichiro YONEDA
Kouji MORIMOTO
Koichi YOSHIDA

Director, RI Application Research Group
Director, Safety Management GroupTeam Leader, RIBF User Liaison Team
Team Leader, Superheavy Element Research Device Development Team
Team Leader, BigRIPS Team

External members
Kentaro YAKO
Hidetoshi YAMAGUCHI
Yutaka WATANABE

Associate Professor, Center for Nuclear Study, University of Tokyo
Lecturer, Center for Nuclear Study, University of Tokyo
Associate Professor, High Energy Accelerator Research Organization, KEK

ObserversHideto EN'YO
Susumu SHIMOURA
Michiharu WADA
Kosuke MORITA
Hideaki OTSU
Atsushi YOSHIDA
Tohru MOTOBAYASHI
Hideyuki SAKAI
Kathrin WIMMER
Yasuhiro SAKEMI
Koichi ABE
Kazushige FUKUSHIMA

Director, RNC
Director, Center for Nuclear Study, University of Tokyo
Director, KEK Wako Nuclear Science Center
Director, Superheavy Element Research GroupTeam Leader, SAMURAI Team
Team Leader, Industrial Cooperation Team
Senior Advisor, RNC
Senior Advisor, RNC
Lecturer, University of Tokyo; Chair, The RIBF Users Executive Committee (RIBF-UEC)
Professor, Center for Nuclear Study, University of Tokyo
Director, Nishina Center and iTHEMS Promotion Office
Manager, Nishina Center and iTHEMS Promotion OfficePublic Relations Committee
Upon request of the RNC Director, the Public Relations Committee deliberates and coordinates the following matters:Creating public relations system for RNC
Prioritization of the public relations activities for RNC
Other general and important matters concerning the public relations of RNC

Members (as of March 31, 2020)
Koichi ABE (Chair)
Hiroyoshi SAKURAI
Osamu KAMIGAITO
Tomoko ABE
Tetsuo HATSUDA
Masahiko IWASAKI
Tomohiro UESAKA
Hideki UENO
Toru TAMAGAWA
Emiko HIYAMA
Kosuke MORITA

Director, Nishina Center and iTHEMS Promotion Office
Deputy Director, RNC; Director, Radioactive Isotope Physics Laboratory
Deputy Director, RNC; Director, Accelerator Group
Deputy Director, RNC; Director, Beam Mutagenesis Group
Director, Quantum Hadron Physics Laboratory
Director, Meson Science Laboratory
Director, Spin Isospin Laboratory and Research Instruments Group
Director, Nuclear Spectroscopy Laboratory and User Liaison Group
Director, High Energy Astrophysics Laboratory
Director, Strangeness Nuclear Physics Laboratory
Director, Superheavy Element Research Group

RBRC Management Steering Committee (MSC)
RBRC MSC is set up according to the Memorandum of Understanding between RIKEN and BNL concerning the collaboration on the Spin
Physics Program at the Relativistic Heavy Ion Collider (RHIC). The 25th MSC was held on May 24, 2019.
Members (as of May 24, 2019)
Motoko KOTANI
Tetsuo HATSUDA
Shoji NAGAMIYA
Robert TRIBBLE
Dmitori DENISOV
Berndt MUELLER

Executive Director, RIKEN
Program Director, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program
Senior Visiting Scientist, RNC
Deputy Director for Science and Technology, BNL
Deputy Associate Laboratory Director for High Energy Physics, BNL
Associate Laboratory Director for Nuclear and Particle Physics, BNL

6. International Collaboration

Country

Partner InstituteObjects- 241 -

RNC contact person

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Austria

Stefan Meyer Institute forSubatomic Physics

Framework

Masahiko IWASAKI, Director, Meson Science
Laboratory

China

China Nuclear Physics Society

Creation of the council for China -Japan
research collaboration on nuclear physics

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

Peking University

Nuclear Science

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

Institute of Modern Physics,
Chinese Academy of Science

Physics of heavy ions

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

School of Nuclear Science andTechnology, Lanzhou University

Framework

Masahiko IWASAKI, Director, Meson Science
Laboratory

School of Physics, Nanjing
University

Framework

Emiko HIYAMA, Director, Strangeness Nuclear
Physics Laboratory

Department of Physics, Faculty of
Science, The University of Hong
Kong

Experimental and educational researchcollaboration in experimental nuclear physics

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

School of physics, Nankai
University

Framework

Emiko HIYAMA, Director, Strangeness Nuclear
Physics Laboratory

Finland

University of Jyvaskyla

Basic nuclear physics and related
instrumentation

Hironobu ISHIYAMA, Team Leader, SLOWRITeamFranceNational Institute of Nuclear
Physics and Particle Physics(IN2P3)

Physics of heavy ions

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Normandy University

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Technische Universität München

Nuclear physics, hadron physics, nuclear
astrophysics

Emiko HIYAMA, Director, Strangeness Nuclear
Physics Laboratory

GSI

Physics of heavy ions and accelerator

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

Department of Physics,
Technische Universität Darmstadt

Framework

Emiko HIYAMA, Director, Strangeness Nuclear
Physics Laboratory

Hungary

The Institute of Nuclear Researchof the Hungarian Academy of
Sciences (ATOMKI)

Nuclear physics, Atomic Physics

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Indonesia

ITB, UNPAD, ITS, UGM, UI

Material science using muons at the RIKENRAL muon facility

Masahiko IWASAKI, Director, Meson Science
Laboratory

Hasanuddin University

Agricultural science and related fields
involving heavy-ion beam mutagenesis using
Indonesian crops

Tomoko ABE, Director, Beam Mutagenesis Group

Applied Physics Division,
National Institute for New
Technologies, Energy andEnvironment (ENEA)

Framework

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

European Center for Theoretical
Studies in Nuclear Physics andRelated Areas (ECT*)

Theoretical physics

Tetsuo HATSUDA, Director, Quantum Hadron
Physics Laboratory

Istituto Nazionale di Fisica
Nucleare (INFN)

Physics of heavy ions

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

Germany

Italy

Country

Partner InstituteObjects

RNC contact person

Seoul National University

Nishina School

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

College of Natural Science, Ewha
Women’s University

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

College of Natural Sciences,
INHA University

Framework

Emiko HIYAMA, Director, Strangeness Nuclear
Physics Laboratory

Malaysia

Universiti Sains Malaysia

Muon Science

Masahiko IWASAKI, Director, Meson Science
Laboratory

NorwayFaculty of Mathematics andNatural Science, University ofOslo（UiO MN）

Framework

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

Korea- 242 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

PolandThe Henryk Niewodniczanski
Institute of Nuclear
Physics, Polish Academy of
Sciences(IFPAN)

Framework

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

Romania“Horia Hulubei” National
Institute of Physics and Nuclear
Engineering Bucharest-Magurele,
Romania

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

University of Bucharest

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Joint Institute for Nuclear
Research (JINR)

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Russian Research Center“Kurchatov Institute”

Framework

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

Switzerland

Paul Scherrer InstituteImprove the performance and reliability ofaccelerator systems

Osamu KAMIGAITO, Director, Accelerator GroupUSA

Columbia University

The development of QCDCQ

Hideto EN’YO, Director, Radiation Laboratory

Michigan State University

Comprehensive
The use of TPC (Time Projection Chamber)

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

VietnamVietnam Atomic Energy
Commission

Framework

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

EuropeEuropean Nuclear Science andApplication
Research2

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

The European Organization for
Nuclear Research (CERN)

R&D and application of micro-pattern gas
detectors (MPGD) technology (RD51
Collaboration)

Hideto EN’YO, Director, Radiation Laboratory

The European Organization for
Nuclear Research (CERN)

Collaboration in the ALICE Experiment

Hideto EN’YO, Director, Radiation Laboratory

Russia7. Awards
Awardee, Laboratory / TeamAward

Organization

Date

Emiko HIYAMA, Director, Strangeness Nuclear Physics
Laboratory

The FY 2019 Prize for Science andTechnology, the Commendation for
Science and Technology by the
Minister of Education, Culture, Sports,
Science and Technology

The Minister of Education, Culture,
Sports, Science and Technology

Apr. 17

Daiki MORI, Technical Staff, Nuclear Chemistry
Research Team

Young Scientist Oral Presentation
Award at 56th Annual Meeting onRadioisotopes and Radiation
Researchers

Japan Radioisotope Association

Jul. 4

Nozomi SATO, Research Part-time Worker, Nuclear
Chemistry Research TeamIUPAC Periodic Table of Younger
Chemists

IUPAC

Jul. 8

Yasushi ABE, Visiting Scientist, Instrumentation
Development GroupThe 16th PASJ Annual Award forposter presentation

Particle Accelerator Society of Japan

Aug. 3

Akio TOMIYA, Special Postdoctoral Researcher,Computing GroupThe 13th Particle Physics Medal(FY2019): Young Scientist Award in
Theoretical Particle Physics

Particle Theory Committee

Sep. 19

Kosuke MORITA, Director, Superheavy Element
Research GroupThe 2019 Kimura Award

The Japan Society of Nuclear andRadiochemical Sciences (JNRS)

Sep. 25- 243 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Koichi YOSHIDA, Team Leader, BigRIPS TeamThe Saitama prefecture High-pressure
Gas Chairman Commendation

The Saitama prefecture High-pressure
Gas Committee

Oct. 23

A joint research group of RNC's Safety Management
Group and the Neutron Beam Technology Team of
RIKEN Center for Advanced Photonics

2019 Symposium on Nuclear Data
Poster Presentation Award

Atomic Energy Society of Japan
Nuclear Data Division

Nov.28

Tomoya NAITO, Student Trainee, Quantum Hadron
Physics Laboratory2020 CAEN Best Young Speaker
Award

Organizing Comettee of "Vth Topical
Workshop on Modern Aspects inNuclear Structure"

Feb. 8Hiromitsu HABA, Director, the RI Application Group

Open Innovation Prize(President of Science Council of Japan
Prize)

Cabinet Office, Government of Japan

Feb. 27- 244 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

8. Brief overview of the RI Beam Factory
Intensity of Primary Beams
Achieved beam intensities (as of March 2019)
238U

Xe
86
Kr
78Kr
70
Zn
48Ca
18O
14N
4He
d
pol. d124

94 pnA (345 MeV/nucleon, Nov. 2019)173 pnA (345 MeV/nucleon, Jun. 2019)30 pnA (345 MeV/nucleon, Nov. 2007)
486 pnA (345 MeV/nucleon, May. 2015)
250 pnA (345 MeV/nucleon, May 2017)730 pnA (345 MeV/nucleon, Nov. 2016)
1000 pnA (345 MeV/nucleon, Jun. 2010)
400 pnA (250 MeV/nucleon, Oct. 2010)
1000 pnA (250 MeV/nucleon, Oct. 2009)
1000 pnA (250 MeV/nucleon, Oct. 2010)
120 pnA, P~80% (250 MeV/nucleon, May 2015)

History of Beam Intensity Upgrade- 245 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Total beam time for experiments

Total beam time allocated to BigRIPS experiments- 246 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Radioactive Isotope Physics Laboratory
1. Abstract

This Laboratory works as one of core research groups conducting programs at the world-premiere heavy-ion accelerator facilityof RIKEN “RI Beam Factory (RIBF).” The Laboratory explores exotic nuclear structures and dynamics in exotic nuclei that havenever been investigated before, such as those with largely imbalanced proton and neutron numbers. Our aim is to develop new
experimental techniques utilizing fast radioactive isotope (RI) beams at RIBF, to discover new phenomena and properties in exotic
nuclei. The Laboratory is focusing three major subjects; shell evolution of very neutron-rich nuclei, the r-process path and equationof-state in asymmetric nuclear matter. The Laboratory has initiated international collaborations for in-beam gamma spectroscopy,
decay spectroscopy and heavy-ion induced reactions, and has formed a discussion forum for next generation gamma-ray detectors.

2. Major Research Subjects(1) Study of structure and dynamics of exotic nuclei through developments of new tools in terms of reaction- and technique-based
methodology(2) Research on EOS in asymmetric nuclear matter via heavy-ion induced reactions(3) Detector developments for spectroscopy and reaction studies

3. Summary of Research Activity(1) In-beam gamma spectroscopy
In the medium and heavy mass region explored at RIBF, collective natures of nuclei are one of important subjects, which are
obtained through production and observation of high excited and high spin states. To populate such states, heavy-ion induced reactions
such as fragmentation, fission are useful. So far, we have developed two-step fragmentation method as an eﬃcient method to identify
and populate excited states, and lifetime measurements to deduce transition strength.
Devices utilized for the in-beam gamma spectroscopy are ZeroDegree Spectrometer (ZDS) and a NaI array DALI2. Since the endof 2008, the first spectroscopy on nuclei island-of-inversion region was performed, we have explored step-by-step new and unknown
regions in the nuclear chart. The second campaign in 2009 was organized to study background components originating from atomic
processes in a heavy target. Neutron-rich nuclei at N = 20 to 28 were studied in 2010. In 2011–2013, we conducted experiment
programs for Ca-54, Ni-78, neutron-rich nuclei at N = 82 and neutron-deficient nuclei at Z = 50.
A multitude of data obtained with inelastic, nucleon knock-out, fragmentation channels have been analyzed and published. In
2011–2013, collective natures of Mg-36, 38 and Si-42 were both published in PRL. Excited states firstly observed in Ca-54 werereported in Nature to demonstrate a new nuclear magic number of 34. Fragmentation reaction has been found eﬃcient for nuclei
with A > 100 and low-lying excited state in Pd-126 has been successfully observed and reported in PRC. In 2019, results of the first
spectrosocpy of 40 Mg was published in PRL, to demonstrate the exotic structure which is very diﬀerent from in other neutron-rich Mg
isotopes.
To further strengthen the in-beam gamma spectroscopy at RIBF, we have proposed a new setup of MINOS + DALI2 to search
for the 1st excited states in even-even neutron-rich nuclei with Z ∼ 20 to 40. The program was submitted to the PAC 2013 as a
new category of proposal, “proposal for scientific program” and was S-ranked. A dedicated collaboration “SEASTAR” has been
established as a subset of in-beam gamma collaboration “SUNFLOWER.” The three campaigns were organized in 2014, 2015 and2017 to study very neutron-rich isotopes, and were very productive to access very neutron-rich nuclei such as Ar-52, Ca-56, Ni-78,
Kr-100, Zr-110. In 2019, the result of the first spectroscopy was published in Nature.
A new project of high resolution gamma spectroscopy with fast beams “HiCARI” has been proposed at PAC 2018 and thecampaign programs are scheduled in 2020. MINIBALL and several Ge tracking detectors from Japan, Europe, the USA and Korea
are being combined to form an array of germanium detectors. The new setup aims to accelerate researches of the nuclear structure byobserving gamma-lines in even-odd nuclei and measuring lifetimes of excited states. The two workshops were organized in 2019, andthe machine time of 43.5 days in total was approved at PAC 2019.
Concerning a next generation detector, a discussion forum has been established to write up a white paper on tracking germanium
detectors and high-eﬃcient crystal detectors such LaBr3 and GAGG.
(2) Decay spectroscopy
Beta- and isomer-spectroscopy is an eﬃcient method for studying nuclear structure, especially for non-yrast levels. We had
accumulated experimental techniques at the RIPS facility to investigate nuclear structure in light mass region via beta-gamma andbeta-p coincidence. Concerning the medium and heavy mass region available at RIBF, we have developed two position-sensitive
active-stoppers, strip-silicon detectors and a cylindrical active stopper called CAITEN, to achieve a low-background measurement by
taking correlation between heavy ion stop position and beta-ray emission position. A site of decay-spectroscopy at the new facility of
RIBF is the final focal plane of ZDS, where high precision of TOF in particle identification is obtained due to a long flight path fromBigRIPS to ZDS.
At the end of 2009, the first decay spectroscopy was organized with a minimum setup of four clover gamma detectors and silicon
strip detectors, to study neutron-rich nuclei with A ∼ 110. The first campaign was found successful and eﬃcient to publish four
letter articles in 2011, two PRL’s and two PLB’s. One of the PRL papers is associated to the r-process path where half-lives for 18- 247 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

neutron-rich nuclei were determined for the first time. The other PRL paper reported a finding of deformed magic number 64 in the
Zr isotopes.
The success of the first decay-spectroscopy campaign stimulated to form a new large-scale collaboration “EURICA,” where a
twelve Euroball cluster array is coupled with the silicon-strip detectors to enhance gamma eﬃciency by a factor of 10. A construction
proposal of “EURICA” was approved in the PAC 2011, and the commissioning was successfully organized in spring 2012. Since
then, physics runs had been conducted for programs approved to survey nuclei of interest as many as possible, such as Ni-78, Pd-128,
Sn-100. The EURICA collaboration finished its physics programs in summer 2016. So far, 54 papers including 14 PRL’s and 13
PLB’s were published. One of the highlights is discovery of a seniority isomer in Pd-128, of which cascade gamma decay gives theenergy of first excited state and robustness of N = 82 magic number, and the other is a half-life measurement for 110 neutron-richnuclei across the N = 82 shell gap, which shows implications for the mechanism and universality of the r-process path.
Beta-delayed neutron emission probability of medium and heavy neutron-rich nuclei is important to understand nuclear structure
and the r-process path. In 2013, a new collaboration “BRIKEN” has been established to form a He-3 detector array. A present
design of the array has neutron eﬃciency as high as 70% up to 3 MeV. The array was coupled with the AIDA silicon strip system. A
construction proposal was approved at the PAC 2013 and three physics proposals have been approved. The commissioning run was
conducted in autumn 2016. The major physics runs were conducted in 2017–2019.
The CAITEN detector was successfully tested with fragments produced with a Ca-48 beam in 2010.
(3) Equation-of-state via heavy-ion central collisions
Equation-of-state in asymmetric nuclear matter is one of major subjects in physics of exotic nuclei. Pi-plus and pi-minus yields
in central heavy ion collisions at the RIBF energy are considered as one of EOS sensitive observables at the RIBF energy. To observecharged pions, a TPC for the SAMURAI spectrometer is being constructed under an international collaboration “SπRIT,” Construction
proposal was submitted at the PAC 2012, and physics proposals were approved at the PAC 2012 and 2013. The physics runs weresuccessfully conducted in spring 2016. The data analysis is in progress to produce the first physics results.
An international symposium “NuSYM” on nuclear symmetry energy was organized at RIKEN July 2010 to invite researchers
in three sub-fields, nuclear structure, nuclear reaction and nuclear astrophysics, and to discuss nuclear symmetry energy together.
Since then, the symposium series have been held every year and been useful to encourage theoretical works and to strengthen thecollaboration.
(4) Nucleon correlation and cluster in nuclei
Nucleon correlation and cluster in nuclei are matters of central focus in a “beyond mean-field” picture. The relevant programswith in-beam gamma and missing-mass techniques are to depict nucleon condensations and correlations in nuclear media as a functionof density as well as temperature. Neutron-halo and –skin nuclei are objects to study dilute neutron matter at the surface. By changing
excitation energies in neutron-rich nuclei, clustering phenomena and role of neutrons are to be investigated.
In 2013, two programs were conducted at the SAMURAI spectrometer. One is related to proton-neutron correlation in the C-12
nucleus via p-n knockout reaction with a carbon target. The other is to search for a cluster state in C-16, which was populated via
inelastic alpha scattering. The data is being analyzed.
In 2018, a new project based on missing mass spectroscopy was launched to investigate an exotic cluster state in a very protonrich nucleus. The experiment was organized at GANIL with combination of RIKEN liquid hydrogen target CRYPTA and the MUST2
detector array in 2018.

Members
Group Director
Hiroyoshi SAKURAI (Deputy Director, RNC)
Special Temporary Research Scientist
Takashi ICHIHARA
Research/Technical Scientists
Yoichi NAKAI (Senior Research Scientist)
Tadaaki ISOBE (Senior Research Scientist)
Akihisa KOHAMA (Senior Research Scientist)

Pieter Christiaan DOORNENBAL (Senior Research Scientist)
Shunji NISHIMURA (Senior Research Scientist)
Daisuke SUZUKI (Research Scientist)

Research Consultants
Akitsu IKEDA
Masayasu ISHIHARA

Kenichi MATSUYANAGI
Hiroyuki MURAKAMI

Special Postdoctoral Researcher
Browne FRANK- 248 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Visiting Researcher
Alejandro ALGORA (JSPS)
Benoit J. C. MAUSS (JSPS)

Byul MOON (Nat’l Res. Foundation)

Junior Research Associates
Hideki SHIMIZU (Univ. of Tokyo)

Takuma KOIWAI (Univ. of Tokyo)

International Program Associates
Juan SAIZ LOMAS (Univ. of York)

Xiaohui SUN (Peking Univ.)

Senior Visiting Scientists
Koichiro ASAHI (Tokyo Tech)
Shigeru KUBONO (Univ. of Tokyo)

Kengo OGAWA (Chiba Univ.)

Visiting Scientists
Nori AOI (Osaka Univ.)
Giordano CERIZZA (Michigan State Univ.)
Jin-hee CHANG (Michigan State Univ.)
Silvio CHERUBINI (Univ. of Catania)
Martha Liliana CORTES SUA (INFN)
Mitsunori FUKUDA (Osaka Univ.)
Byungsik HONG (Korea Univ.)
Kazuo IEKI (Rikkyo Univ.)
Kei IIDA (Kochi Univ.)
Natsumi IKENO (Tottori Univ.)
Takuji IZUMIKAWA (Niigata Univ.)
Takashi KISHIDA (Aoyama Gakuin Univ.)
Gabor KISS (ATOMKI)
Khiem LE (Vietnam Academy of Sci. and Tech.)
Hiu Ching LEE (The Univ. of Hong Kong)
Giuseppe LORUSSO (Nat’l Phys. Lab.)
Alan MCINTOSH (Texas A & M Univ.)
Yoshiharu MORI (Kyoto Univ.)
Tetsuya MURAKAMI (Kyoto Univ.)

Megumi NIIKURA (Univ. of Tokyo)
Evgueni NIKOLSKI (Kurchatov Inst.)
Daiki NISHIMURA (Tokyo City Univ.)
Takashi OHTSUBO (Niigata Univ.)
Hooi Jin ONG (Osaka Univ.)
Akira ONO (Tohoku Univ.)
Naohiko OTSUKA (IAEA)
Kazuhiro OYAMATSU (Aichi Shukutoku Univ.)
Clementine Angelique Marie-Th SANTAMARIA (Berkeley
Lab)
Paer-Anders SOEDERSTROEM (TU Darmstadt)
Maya TAKECHI (Niigata Univ.)
Ryo TANIUCHI (Univ. of York)Rensheng WANG (Soochow Univ.)
Hiroshi WATANABE (Beihang Univ.)
Kathrin WIMMER (Inst.o de Estructura de la Materia, Consejo
Superior de Investigaciones Cientias, CSIC)
Jin WU (Argonne Nat’l Lab.)
Yasutaka YAMAMOTO (Osaka Univ.)

Visiting Technicians
Jorge AGRAMUNT ROS (Valencia city hall)
Hilde DE WITTE (KU Leuven)

Herbert E. HESS (Univ. of Cologne)
Ivan KOJOUHAROV (GSI)

Student Trainees
Takamichi AOKI (Univ. of Tokyo)
Takumi AOKI (Univ. of Tokyo)
Yusei BANDO (Univ. of Tokyo)
Jonathan BARNEY (Michigan State Univ.)
Linh BUI (Vietnam Atomic Energy Inst.)
Justin B. ESTEE (Michigan State Univ.)
Hiroaki FUKUSHIMA (Rikkyo Univ.)
Shinnosuke KANAYA (Osaka Univ.)
Masanori KANEKO (Kyoto Univ.)
Jiseok KIM (Korea Univ.)
Asahi KOHDA (Osaka Univ.)

Kei KOKUBUN (Univ. of Tokyo)
Shunpei KOYAMA (Univ. of Tokyo)
Jung Woo LEE (Korea Univ.)
Thomas G. PARRY (Univ. of Surrey)
Takeshi SAITO (Univ. of Tokyo)
Hidaka TANABE (Tsukuba Univ.)
Chun Yuen TSANG (Michigan State Univ.)
Phong VI (VNU Univ. of Sci.)
Ryo WAKABAYASHI (Osaka Univ.)
Tik Tsun YEUNG (The Univ. of Hong Kong)
Naoya YOSHIDA (Univ. of Tokyo)

Part-time Worker
Kiyomi ARAI (Research Part-time Worker I)
Mie DOI (Research Part-time Worker I)
Masanori KANEKO (Research Part-time Worker I)
Miki KANOU (Research Part-time Worker I)

Noriko OKAYASU (Research Part-time Worker I)
Tsuneyo SUZUKI (Research Part-time Worker I)
Misuzu KANOU (Research Part-time Worker II)
Eiko MIZUMOTO (Research Part-time Worker II)- 249 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

List of Publications & Presentations
Publications[Original papers]
T. Lokotko, S. Leblond, J. Lee, P. Doornenbal, A. Obertelli, A. Poves, F. Nowacki, K. Ogata, K. Yoshida, G. Authelet, H. Baba, D. Calvet,
F. Chateau, S. Chen, A. Corsi, A. Delbart, J. Gheller, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi,
M. Niikura, H. Otsu, C. Peron, A. Peyaud, E. Pollacco, J. Rousse, H. Sakurai, C. Santamaria, Z. Xu, M. Sasano, Y. Shiga, S. Takeuchi,
R. Taniuchi, T. Uesaka, H. Wang, V. Werner, F. Browne, L. Chung, Z. Dombradi, S. Franchoo, F. Giacoppo, A. Gottardo, K. HadynskaKlek, Z. Korkulu, S. Koyama, Y. Kubota, M. Lettmann, C. Louchart, R. Lozeva, K. Matsui, T. Miyazaki, S. Nishimura, L. Olivier,S. Ota, Z. Patel, E. Sahin, C. Shand, P. Soderstrom, I. Stefan, D. Steppenbeck, T. Sumikama, D. Suzuki, Z. Vajta, and J. Wu, “Shellstructure of the neutron-rich isotopes 69, 71, 73 Co,” Phys. Rev. C 101, 034314 (2020).
Y. Sun, A. Obertelli, P. Doornenbal, C. Barbieri, Y. Chazono, T. Duguet, H. Liu, P. Navratil, F. Nowacki, K. Ogata, T. Otsuka, F. Raimondi,
V. Soma, Y. Utsuno, K. Yoshida, N. Achouri, H. Baba, F. Browne, D. Calvet, F. Chateau, S. Chen, N. Chiga, A. Corsi, M. Cortes,
A. Delbart, J. M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, T. Motobayashi, I. Murray,
H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. Togano, T. Uesaka, K. Wimmer,
K. Yoneda, O. Aktas, T. Aumann, L. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R. B. Gerst, J. Gibelin, K. Hahn, D. Kim, T. Koiwai,
Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Park, D. Rossi, E. Sahin,
D. Sohler, P. A. Soderstrom, S. Takeuchi, H. Tornqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang,
M. Yasuda, and L. Zanetti, ‘Restoration of the natural E(1/2+1 ) − E(3/2+1 ) energy splitting in odd-K isotopes towards N = 40,” Phys.
Lett. B 802, 135215 (2020).
V. Vaquero, A. Jungclaus, T. Aumann, J. Tscheuschner, E. Litvinova, J. Tostevin, H. Baba, D. Ahn, R. Avigo, K. Boretzky, A. Bracco,
C. Caesar, F. Camera, S. Chen, V. Derya, P. Doornenbal, J. Endres, N. Fukuda, U. Garg, A. Giaz, M. Harakeh, M. Heil, A. Horvat,
K. Ieki, N. Imai, N. Inabe, N. Kalantar-Nayestanaki, N. Kobayashi, Y. Kondo, S. Koyama, T. Kubo, I. Martel, M. Matsushita, B. Million, T. Motobayashi, T. Nakamura, N. Nakatsuka, M. Nishimura, S. Nishimura, S. Ota, H. Otsu, T. Ozaki, M. Petri, R. Reifarth,
J. Rodriguez-Sanchez, D. Rossi, A. Saito, H. Sakurai, D. Savran, H. Scheit, F. Schindler, P. Schrock, D. Semmler, Y. Shiga, M. Shikata,Y. Shimizu, H. Simon, D. Steppenbeck, H. Suzuki, T. Sumikama, D. Symochko, I. Syndikus, H. Takeda, S. Takeuchi, R. Taniuchi,
Y. Togano, J. Tsubota, H. Wang, O. Wieland, K. Yoneda, J. Zenihiro, and A. Zilges, “Fragmentation of single-particle strength aroundthe doubly magic nucleus 132 Sn and the position of the 0f5/2 proton-hole state in 131 In131,” Phys. Rev. Lett. 124, 022501 (2020).
M. Cortes, W. Rodriguez, P. Doornenbal, A. Obertelli, J. Holt, S. Lenzi, J. Menendez, F. Nowacki, K. Ogata, A. Poves, T. Rodriguez,
A. Schwenk, J. Simonis, S. Stroberg, K. Yoshida, L. Achouri, H. Baba, F. Browne, D. Calvet, F. Chateau, S. Chen, N. Chiga, A. Corsi,
A. Delbart, J. M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, H. Liu, T. Motobayashi,
I. Murray, H. Otsu, V. Panin, N. Paul, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. Sun, Y. Togano, T. Uesaka, K. Wimmer,
K. Yoneda, O. Aktas, T. Aumann, L. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R. B. Gerst, J. Gibelin, K. Hahn, D. Kim, T. Koiwai,
Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Park, D. Rossi,
E. Sahin, D. Sohler, P. A. Soderstrom, S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada,
D. Yan, Z. Yang, M. Yasuda, and L. Zanetti, “Shell evolution of N = 40 isotones towards 60 Ca: First spectroscopy of 62 Ti,” Phys. Lett.
B 800, 135071 (2020).
M. Tanaka, M. Takechi, A. Homma, M. Fukuda, D. Nishimura, T. Suzuki, Y. Tanaka, T. Moriguchi, D. Ahn, A. Aimaganbetov, M. Amano,
H. Arakawa, S. Bagchi, K. Behr, N. Burtebayev, K. Chikaato, H. Du, S. Ebata, T. Fujii, N. Fukuda, H. Geissel, T. Hori, W. Horiuchi,
S. Hoshino, R. Igosawa, A. Ikeda, N. Inabe, K. Inomata, K. Itahashi, T. Izumikawa, D. Kamioka, N. Kanda, I. Kato, I. Kenzhina,
Z. Korkulu, Y. Kuk, K. Kusaka, K. Matsuta, M. Mihara, E. Miyata, D. Nagae, S. Nakamura, M. Nassurlla, K. Nishimuro, K. Nishizuka,
K. Ohnishi, M. Ohtake, T. Ohtsubo, S. Omika, H. Ong, A. Ozawa, A. Prochazka, H. Sakurai, C. Scheidenberger, Y. Shimizu, T. Sugihara, T. Sumikama, H. Suzuki, S. Suzuki, H. Takeda, Y. Tanaka, I. Tanihata, T. Wada, K. Wakayama, S. Yagi, T. Yamaguchi, R. Yanagihara, Y. Yanagisawa, K. Yoshida, and T. Zholdybayev, “Swelling of doubly magic 48 Ca core in Ca isotopes beyond N = 28,” Phys.
Rev. Lett. 124, 102501 (2020).
G. Zhang, H. Watanabe, G. Dracoulis, F. Kondev, G. Lane, P. Regan, P. A. Soderstrom, P. Walker, K. Yoshida, H. Kanaoka, Z. Korkulu,
P. Lee, J. Liu, S. Nishimura, J. Wu, A. Yagi, D. Ahn, T. Alharbi, H. Baba, F. Browne, A. Bruce, M. Carpenter, R. Carroll, K. Chae,
C. Chiara, Z. Dombradi, P. Doornenbal, A. Estrade, N. Fukuda, C. Griﬃn, E. Ideguchi, N. Inabe, T. Isobe, S. Kanaya, I. Kojouharov,
T. Kubo, S. Kubono, N. Kurz, I. Kuti, S. Lalkovski, T. Lauritsen, C. Lee, E. Lee, C. Lister, G. Lorusso, G. Lotay, E. McCutchan,
C. B. Moon, I. Nishizuka, C. Nita, A. Odahara, Z. Patel, V. Phong, Z. Podolyak, O. Roberts, H. Sakurai, H. Schaﬀner, D. Seweryniak,
C. Shand, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda, S. Terashima, Z. Vajta, J. Valiente-Dobon, Z. Xu, and S. Zhu, “Interplay ofquasiparticle and vibrational excitations: First observation of isomeric states in 168 Dy and 169 Dy,” Phys. Lett. B 799, 135036 (2019).
L. Sinclair, R. Wadsworth, J. Dobaczewski, A. Pastore, G. Lorusso, H. Suzuki, D. Ahn, H. Baba, F. Browne, P. Davies, P. Doornenbal,
A. Estrade, Y. Fang, N. Fukuda, J. Henderson, T. Isobe, D. Jenkins, S. Kubono, Z. Li, D. Lubos, S. Nishimura, I. Nishizuka, Z. Patel,
S. Rice, H. Sakurai, Y. Shimizu, P. Schury, H. Takeda, P. Soderstrom, T. Sumikama, H. Watanabe, V. Werner, J. Wu, and Z. Xu,“Half-lives of 73 Sr and 76 Y and the consequences for the proton dripline,” Phys. Rev. C 100, 044311 (2019).
K. Nakano, Y. Watanabe, S. Kawase, H. Wang, H. Otsu, H. Sakurai, S. Takeuchi, Y. Togano, T. Nakamura, Y. Maeda, D. S. Ahn,
M. Aikawa, S. Araki, S. Chen, N. Chiga, P. Doornenbal, N. Fukuda, T. Ichihara, T. Isobe, S. Kawakami, T. Kin, Y. Kondo, S. Koyama,
T. Kubo, S. Kubono, M. Uesaka, A. Makinaga, M. Matsushita, T. Matsuzaki, S. Michimasa, S. Momiyama, S. Nagamine, M. Niikura,T. Ozaki, A. Saito, T. Saito, Y. Shiga, M. Shikata, Y. Shimizu, S. Shimoura, T. Sumikama, P. A. Soderstrom, H. Suzuki, H. Takeda,
R. Taniuchi, J. Tsubota, Y. Watanabe, K. Wimmer, T. Yamamoto, and K. Yoshida, “Isotope production in proton-, deuteron-, andcarbon-induced reactions on 93 Nb at 113 MeV/nucleon,” Phys. Rev. C 100, 044605 (2019).
S. Chen, J. Lee, P. Doornenbal, A. Obertelli, C. Barbieri, Y. Chazono, P. Navratil, K. Ogata, T. Otsuka, F. Raimondi, V. Soma, Y. Utsuno,
K. Yoshida, H. Baba, F. Browne, D. Calvet, F. Chateau, N. Chiga, A. Corsi, M. Cortes, A. Delbart, J. Gheller, A. Giganon, A. Gillibert,- 250 -

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C. Hilaire, T. Isobe, J. Kahlbow, T. Kobayashi, Y. Kubota, V. Lapoux, H. Liu, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul,
W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, N. Achouri,
O. Aktas, T. Aumann, L. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R. Gerst, J. Gibelin, K. Hahn, D. Kim, T. Koiwai, Y. Kondo,
P. Koseoglou, C. Lehr, B. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Park, D. Rossi, E. Sahin, D. Sohler,
P. Soderstrom, S. Takeuchi, H. Tornqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda,and L. Zanetti, “Quasifree neutron knockout from 54 Ca corroborates arising N = 34 Neutron magic number,” Phys. Rev. Lett. 123,
142501 (2019).
R. Yokoyama, R. Grzywacz, B. Rasco, N. Brewer, K. Rykaczewski, I. Dillmann, J. Tain, S. Nishimura, D. Ahn, A. Algora, J. Allmond,
J. Agramunt, H. Baba, S. Bae, C. Bruno, R. Caballero-Folch, F. Calvino, P. Coleman-Smith, G. Cortes, T. Davinson, C. Domingo-Pardo,
A. Estrade, N. Fukuda, S. Go, C. Griﬃn, J. Ha, O. Hall, L. Harkness-Brennan, J. Heideman, T. Isobe, D. Kahl, M. Karny, T. Kawano,
L. Khiem, T. King, G. Kiss, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, J. Liang, J. Liu, G. Lorusso, M. Madurga, K. Matsui,
K. Miernik, F. Montes, A. Morales, P. Morrall, N. Nepal, R. Page, V. Phong, M. Piersa, M. Prydderch, V. Pucknell, M. Rajabali,
B. Rubio, Y. Saito, H. Sakurai, Y. Shimizu, J. Simpson, M. Singh, D. Stracener, T. Sumikama, R. Surman, H. Suzuki, H. Takeda,
A. Tarifeno-Saldivia, S. Thomas, A. Tolosa-Delgado, M. Wolinska-Cichocka, P. Woods, and X. Xu, “Strong one-neutron emission
from two-neutron unbound states in β decays of the r -process nuclei 86, 87 Ga,” Phys. Rev. C 100, 031302 (2019).
V. Phong, G. Lorusso, T. Davinson, A. Estrade, O. Hall, J. Liu, K. Matsui, F. Montes, S. Nishimura, A. Boso, P. Regan, R. Shearman,
Z. Xu, J. Agramunt, J. Allmond, D. Ahn, A. Algora, H. Baba, N. Brewer, C. Bruno, R. Caballero-Folch, F. Calvino, M. WolinskaCichocka, G. Cortes, I. Dillmann, C. Domingo-Pardo, A. Gargano, S. Go, C. Griﬃn, R. Grzywacz, L. Harkness-Brennan, T. Isobe,
A. Jungclaus, D. Kahl, L. Khiem, G. Kiss, A. Korgul, S. Kubono, K. Miernik, A. Morales, N. Nepal, M. Piersa, Z. Podolyak, B. Rasco,
K. Rykaczewski, H. Sakurai, Y. Shimizu, D. Stacener, T. Sumikama, H. Suzuki, H. Takeda, J. Tain, A. Tarifeno-Saldivia, A. TolosaDelgado, V. Vaquero, P. Woods, R. Yokoyama, and C. Yuan, “Observation of a µs isomer in 134
49 In85 : Proton-neutron coupling “southeast” of 132
50 Sn82 ,” Phys. Rev. C 100, 011302 (2019).
V. Vaquero, A. Jungclaus, J. Rodriguez-Sanchez, J. Tostevin, P. Doornenbal, K. Wimmer, S. Chen, E. Nacher, E. Sahin, Y. Shiga, D. Steppenbeck, R. Taniuchi, Z. Xu, T. Ando, H. Baba, F. Bello Garrote, S. Franchoo, A. Gargano, K. Hadynska-Klek, A. Kusoglu, J. Liu,
T. Lokotko, S. Momiyama, T. Motobayashi, S. Nagamine, N. Nakatsuka, M. Niikura, R. Orlandi, T. Saito, H. Sakurai, P. Soderstrom,
G. Tveten, Z. Vajta, and M. Yalcinkaya, “Inclusive cross sections for one- and multi-nucleon removal from Sn, Sb, and Te projectiles
beyond the N = 82 shell closure,” Phys. Lett. B 795, 356–361 (2019).
K. Wimmer, P. Doornenbal, W. Korten, T. Arici, P. Aguilera, A. Algora, T. Ando, H. Baba, B. Blank, A. Boso, S. Chen, A. Corsi,
P. Davies, G. de Angelis, G. de France, D. Doherty, J. Gerl, R. Gernhauser, D. Jenkins, S. Koyama, T. Motobayashi, S. Nagamine,
M. Niikura, A. Obertelli, D. Lubos, B. Rubio, E. Sahin, T. Saito, H. Sakurai, L. Sinclair, D. Steppenbeck, R. Taniuchi, R. Wadsworth,and M. Zielinska, “Discovery of 68 Br in secondary reactions of radioactive beams,” Phys. Lett. B 795, 266–270 (2019).
D. Lubos, J. Park, T. Faestermann, R. Gernhauser, R. Krucken, M. Lewitowicz, S. Nishimura, H. Sakurai, D. Ahn, H. Baba, B. Blank,
A. Blazhev, P. Boutachkov, F. Browne, I. Celikovic, G. de France, P. Doornenbal, Y. Fang, N. Fukuda, J. Giovinazzo, N. Goel,
M. Gorska, S. Ilieva, N. Inabe, T. Isobe, A. Jungclaus, D. Kameda, Y. Kim, I. Kojouharov, T. Kubo, N. Kurz, Y. Kwon, G. Lorusso,
K. Moschner, D. Murai, I. Nishizuka, Z. Patel, M. Rajabali, S. Rice, H. Schaﬀner, Y. Shimizu, L. Sinclair, P. Soderstrom, K. Steiger,
T. Sumikama, H. Suzuki, H. Takeda, Z. Wang, N. Warr, H. Watanabe, J. Wu, and Z. Xu, “Improved value for the gamow-teller strengthof the 100 Sn beta decay,” Phys. Rev. Lett. 122, 222502 (2019).
Z. Chen, Z. Li, H. Hua, H. Watanabe, C. Yuan, S. Zhang, G. Lorusso, S. Nishimura, H. Baba, F. Browne, G. Benzoni, K. Chae, F. Crespi,
P. Doornenbal, N. Fukuda, G. Gey, R. Gernhauser, N. Inabe, T. Isobe, D. Jiang, A. Jungclaus, H. Jung, Y. Jin, D. Kameda, G. Kim,
Y. Kim, I. Kojouharov, F. Kondev, T. Kubo, N. Kurz, Y. Kwon, X. Li, J. Lou, G. Lane, C. Li, D. Luo, A. Montaner-Piza, K. Moschner,
C. Niu, F. Naqvi, M. Niikura, H. Nishibata, A. Odahara, R. Orlandi, Z. Patel, Z. Podolyak, T. Sumikama, P. Soderstrom, H. Sakurai,
H. Schaﬀner, G. Simpson, K. Steiger, H. Suzuki, J. Taprogge, H. Takeda, Z. Vajta, H. Wang, J. Wu, A. Wendt, C. Wang, H. Wu,
X. Wang, C. Wu, C. Xu, Z. Xu, A. Yagi, Y. Ye, and K. Yoshinaga, “Proton shell evolution below 132 Sn: first measurement of low-lying
β-emitting isomers in 123, 125 Ag,” Phys. Rev. Lett. 122, 212502 (2019).
R. Taniuchi, C. Santamaria, P. Doornenbal, A. Obertelli, K. Yoneda, G. Authelet, H. Baba, D. Calvet, F. Chateau, A. Corsi, A. Delbart,
J. M. Gheller, A. Gillibert, J. Holt, T. Isobe, V. Lapoux, M. Matsushita, J. Menendez, S. Momiyama, T. Motobayashi, M. Niikura,
F. Nowacki, K. Ogata, H. Otsu, T. Otsuka, C. Peron, S. Peru, A. Peyaud, E. Pollacco, A. Poves, J. Y. Rousse, H. Sakurai, A. Schwenk,
Y. Shiga, J. Simonis, S. Stroberg, S. Takeuchi, Y. Tsunoda, T. Uesaka, H. Wang, F. Browne, L. Chung, Z. Dombradi, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadynska-Klek, Z. Korkulu, S. Koyama, Y. Kubota, J. Lee, M. Lettmann, C. Louchart, R. Lozeva, K. Matsui,
T. Miyazaki, S. Nishimura, L. Olivier, S. Ota, Z. Patel, E. Sahin, C. Shand, P. A. Soderstrom, I. Stefan, D. Steppenbeck, T. Sumikama,
D. Suzuki, Z. Vajta, V. Werner, J. Wu, and Z. Xu, “78 Ni revealed as a doubly magic stronghold against nuclear deformation,” Nature
569, 53–58 (2019).
N. Paul, A. Obertelli, C. Bertulani, A. Corsi, P. Doornenbal, J. Rodriguez-Sanchez, G. Authelet, H. Baba, D. Calvet, F. Chateau, S. Chen,
A. Delbart, J. Gheller, A. Giganon, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, M. Niikura,
H. Otsu, C. Peron, A. Peyaud, E. Pollacco, J. Rousse, H. Sakurai, C. Santamaria, M. Sasano, Y. Shiga, D. Steppenbeck, S. Takeuchi,
R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, T. Ando, T. Arici, A. Blazhev, F. Browne, A. Bruce, R. Carroll, L. Chung, M. Cortes,
M. Dewald, B. Ding, Z. Dombradi, F. Flavigny, S. Franchoo, F. Giacoppo, M. Gorska, A. Gottardo, K. Hadynska-Klek, Z. Korkulu,
S. Koyama, Y. Kubota, A. Jungclaus, J. Lee, M. Lettmann, B. Linh, J. Liu, Z. Liu, C. Lizarazo, C. Louchart, R. Lozeva, K. Matsui,
T. Miyazaki, K. Moschner, S. Nagamine, N. Nakatsuka, C. Nita, S. Nishimura, C. Nobs, L. Olivier, S. Ota, Z. Patel, Z. Podolyak,
M. Rudigier, E. Sahin, T. Saito, C. Shand, P. Soderstrom, I. Stefan, T. Sumikama, D. Suzuki, R. Orlandi, V. Vaquero, Z. Vajta,
V. Werner, K. Wimmer, J. Wu, and Z. Xu, “Prominence of Pairing in Inclusive (p, 2p) and (p, pn) Cross Sections from Neutron-Rich
Nuclei,” Phys. Rev. Lett. 122, 162503 (2019).
H. Watanabe, H. Wang, G. Lorusso, S. Nishimura, Z. Xu, T. Sumikama, P. A. Soderstrom, P. Doornenbal, F. Browne, G. Gey, H. Jung,
J. Taprogge, Z. Vajta, J. Wu, A. Yagi, H. Baba, G. Benzoni, K. Chae, F. Crespi, N. Fukuda, R. Gernhauser, N. Inabe, T. Isobe,- 251 -

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A. Jungclaus, D. Kameda, G. Kim, Y. Kim, I. Kojouharov, F. Kondev, T. Kubo, N. Kurz, Y. Kwon, G. Lane, Z. Li, C. B. Moon,
A. Montaner-Piza, K. Moschner, F. Naqvi, M. Niikura, H. Nishibata, D. Nishimura, A. Odahara, R. Orlandi, Z. Patel, Z. Podolyak,
H. Sakurai, H. Schaﬀner, G. Simpson, K. Steiger, Y. Sun, H. Suzuki, H. Takeda, A. Wendt, and K. Yoshinaga, “New isomers in 125 Pd79
and 127 Pd81 : Competing proton and neutron excitations in neutron-rich palladium nuclides towards the N = 82 shell closure,” Phys.
Lett. B 792, 263–268 (2019).
S. Michimasa, J. Hwang, K. Yamada, S. Ota, M. Dozono, N. Imai, K. Yoshida, Y. Yanagisawa, K. Kusaka, M. Ohtake, M. Matsushita,
D. S. Ahn, O. Beliuskina, N. Chiga, K. Chikaato, N. Fukuda, S. Hayakawa, E. Ideguchi, K. Iribe, C. Iwamoto, S. Kawase, K. Kawata,
N. Kitamura, S. Masuoka, H. Miyatake, D. Nagae, R. Nakajima, T. Nakamura, K. Nakano, S. Omika, H. Otsu, H. Sakurai, P. Schrock,H. Shimizu, Y. Shimizu, T. Sumikama, X. Sun, D. Suzuki, H. Suzuki, M. Takaki, M. Takechi, H. Takeda, S. Takeuchi, T. Teranishi,
R. Tsunoda, H. Wang, Y. Watanabe, Y. X. Watanabe, K. Wimmer, K. Yako, H. Yamaguchi, L. Yang, H. Yoshida, and S. Shimoura,“OEDO, the energy-degrading beamline at RI Beam Factory,” PTEP 2019, 043D01 (2019).
J. Hwang, S. Michimasa, S. Ota, M. Dozono, N. Imai, K. Yoshida, Y. Yanagisawa, K. Kusaka, M. Ohtake, D. S. Ahn, O. Beliuskina,
N. Fukuda, C. Iwamoto, S. Kawase, K. Kawata, N. Kitamura, S. Masuoka, H. Otsu, H. Sakurai, P. Schrock, T. Sumikama, H. Suzuki,
M. Takaki, H. Takeda, R. Tsunoda, K. Wimmer, K. Yako, and S. Shimoura, “Angle-tunable wedge degrader for an energy-degrading
RI beamline,” PTEP 2019, 043D02 (2019).
K. Wimmer, F. Recchia, S. Lenzi, S. Riccetto, T. Davinson, A. Estrade, C. Griﬃn, S. Nishimura, F. Nowacki, V. Phong, A. Poves,
P. A. Soderstrom, O. Aktas, M. Al-Aqeel, T. Ando, H. Baba, S. Bae, S. Choi, P. Doornenbal, J. Ha, L. Harkness-Brennan, T. Isobe,
P. John, D. Kahl, G. Kiss, I. Kojouharov, N. Kurz, M. Labiche, K. Matsui, S. Momiyama, D. Napoli, M. Niikura, C. Nita, Y. Saito,
H. Sakurai, H. Schaﬀner, P. Schrock, C. Stahl, T. Sumikama, V. Werner, W. Witt, and P. Woods, “First spectroscopy of 61 Ti and thetransition to the Island of Inversion at N = 40,” Phys. Lett. B 792, 16–20 (2019).
A. Tolosa-Delgado et al. [BRIKEN Collaboration], “Commissioning of the BRIKEN detector for the measurement of very exotic βdelayed neutron emitters,” Nucl. Instrum. Methods Phys. Res. A 925, 133–147 (2019).
X. Xu, J. H. Liu, C. X. Yuan, Y. M. Xing, M. Wang, Y. H. Zhang, X. H. Zhou, Yu. A. Litvinov, K. Blaum, R. J. Chen, X. C. Chen,
C. Y. Fu, B. S. Gao, J. J. He, S. Kubono, Y. H. Lam, H. F. Li, M. L. Liu, X. W. Ma, P. Shuai, M. Si, M. Z. Sun, X. L. Tu, Q. Wang,
H. S. Xu, X. L. Yan, J. C. Yang, Y. J. Yuan, Q. Zeng, P. Zhang, X. Zhou, W. L. Zhan, S. Litvinov, G. Audi, S. Naimi, T. Uesaka,
Y. Yamaguchi, T. Yamaguchi, A. Ozawa, B. H. Sun, K. Kaneko, Y. Sun, and F. R. Xu “Masses of ground and isomeric states of 101 In
and confguration-dependent shell evolution in odd-A Indium isotopes,” Phys. Rev. C100, 051303(R) (2019).
N. T. Zhang, X. Y. Wang, D. Tudor, B. Bucher, I. Burducea, H. Chen, Z. J. Chen, D. Chesneanu, A. I. Chilug, L. R. Gasques, D. G. Ghita,
C. Gomoiu, K. Hagino, S. Kubono, Y. J. Li, C. J. Lin, W. P. Lin, R. Margineanu, A. Pantelica, I. C. Stefanescu, M. Straticiuc,
X. D. Tang, L. Trache, A. S. Umar, W. Y. Xin, S. W. Xu, and Y. Xu, “Constraining the 12 C+12 C astrophysical S-factors with the12
C+13 C measurements at very low energies,” Phys. Lett. B801, 135170 (2020).
B. Elman, A. Gade, R. V. F. Janssens, A. D. Ayangeakaa, D. Bazin, J. Belarge, P. C. Bender, B. A. Brown, C. M. Campbell, M. P. Carpenter,
H. L. Crawford, B. P. Crider, P. Fallon, A. M. Forney, J. Harker, S. N. Liddick, B. Longfellow, E. Lunderberg, C. J. Prokop, J. Sethi,
R. Taniuchi, W. B. Walters, D. Weisshaar, and S. Zhu, “Probing the role of proton cross-shell excitations in 70 Ni using nucleon knockout
reactions,” Phys. Rev. C 100, 034317 (2019).
Y. Ichikawa, H. Nishibata, A. Takamine, K. Imamura, T. Fujita, T. Sato, Y. Shimizu, D. S. Ahn, K. Asahi, H. Baba, D. L. Balabanski,
F. Boulay, J. M. Daugas, N. Fukuda, A. Gladkov, N. Inabe, Y. Ishibashi, Y. Ohtomo, T. Otsuka, T. Sumikama, H. Suzuki, H. Takeda,
L. C. Tao, H. Ueno, and H. Yamazaki, “Interplay between nuclear shell evolution and shape deformation revealed by the magnetic
moment of 75 Cu,” Nat. Phys. 15, 321–325 (2019).
A. Sakurai, B. K. Sahoo, K. Asahi, and B. P. Das, “Relativistic many-body theory of the electric dipole moment of 129 Xe and its implications for probing new physics beyond the standard model,” Phys. Rev. A 100, 020502 (R) (2019).
F. Boulay, G. S. Simpson, Y. Ichikawa, S. Kisyov, D. Bucurescu, A. Takamine, D. S. Ahn, K. Asahi, H. Baba, D. L. Balabanski,
T. Egami, T. Fujita, N. Fukuda, C. Funayama, T. Furukawa, G. Georgiev, A. Gladkov, M. Hass, K. Imamura, N. Inabe, Y. Ishibashi,
T. Kawaguchi, T. Kawamura, W. Kim, Y. Kobayashi, S. Kojima, A. Kusoglu , R. Lozeva, S. Momiyama, I. Mukul, M. Niikura,
H. Nishibata, T. Nishizaka, A. Odahara, Y. Ohtomo, D. Ralet, T. Sato, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda, L. C. Tao,
Y. Togano, D. Tominaga, H. Ueno, H. Yamazaki, X. F. Yang, and J. M. Daugas, “g Factor of the 99 Zr (7/2+ ) isomer: monopole evolution
in the shape-coexisting region,” Phys. Rev. Lett. 124, 112501 (2020).
T. Sonoda, I. Katayama, M. Wada, H. Iimura, V. Sonnenschein, S. Iimura, A. Takamine, M. Rosenbusch, T. M. Kojima, D. S. Ahn,
N. Fukuda, T. Kubo, S. Nishimura, Y. Shimizu, H. Suzuki, H. Takeda, M. Tanigaki, H. Tomita, K. Yoshida, and H. Ishiyama, “Conceptual study on parasitic low-energy RI beam production with in-flight separator BigRIPS and the first stopping examination for
high-energy RI beams in the parasitic gas cell,” Prog. Theor. Exp. Phys. 2019, 113D02 (2019).
G. Häfner, K. Moschner, A. Blazhev, P. Boutachkov, P. J. Davies, R. Wadswroth, F. Ameil, H. Baba, T. Bäck, M. Dewald, P. Doornenbal,
T. Faestermann, A. Gengelbach, J. Gerl, R. Gernháuser, S. Go, M. Górska, H. Grawe, E. Gregor, H. Hotaka, T. Isobe, D. G. Jenkins,
J. Jolie, H. S. Jung, I. Kojouharov, N. Kurz, M. Lewitowicz, G. Lorusso, R. Lozeba, E. Merchan, F. Naqvi, H. Nishibata, D. Nishimura,
S. Nishimura, N. Pietralla, H. Scaﬀner, P. -A. Söderström, K. Steiger, T. Sumikama, J. Taprogge, P. Thöle, H. Watanabe, N. Warr,
V. Werner, Z. Y. Xu, A. Yagi, K. Yoshinaga, and Y. Zhu, “Properties of γ-decaying isomers in the 100 Sn region populated in fragmentation of a 124 Xe beam,” Phys. Rev. C 100, 024302 (2019).
R. Yokoyama, M. Singh, R. Grzywacz, A. Keeler, T. T. King, J. Agramunt, N. T. Brewer, S. Go, J. Heideman, J. Liu, S. Nishimura,
P. Parkhurst, V. H. Phong, M. M. Rajabali, B. C. Rasco, K. P. Rykaczewski, D. W. Stracener, J. L. Tain, A. Tolosa-Delgado, K. Vaigneur,and M. Wolińska-Cichocka, “Segmented YSO scintillation detectors as a new β-implant detection tool for decay spectroscopy infragmentation facilities,” Nucl. Instrum. Methods Phys. Res. A 937, 93–97 (2019).
J. W. Lee et al. [SPiRIT Collaboration], “Charged particle track reconstruction with SπRIT Time Projection Chamber,” Nucl. Instrum.
Methods Phys. Res. A 965, 163840 (2020).

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C. Y. Tsang et al. [SPiRIT Collaboration], “Space charge eﬀects in the SπRIT time projection chamber,” Nucl. Instrum. Methods Phys.
Res. A 959, 163477 (2019).
J. Estee et al. [SPiRIT Collaboration], “Extending the dynamic range of electronics in a Time Projection Chamber,” Nucl. Instrum.
Methods Phys. Res. A 944, 162509 (2019).

[Review articles]୩಺ྏ, ᓎҪതّ, ʮ2 ॏຐ๏਺ͱͦͷഁΕ: χοέϧ 78 ͷΨϯϚઢ෼ޫ͕ղ໌ͨ͠ด֪ੑʯ, ʮ෺ཧՊֶ, ͜ͷ 1 ೥ 2020ʯ, ύϦςΟ2020 ೥ 1 ݄߸, pp.86–89, ‫ؙ‬ળग़൛, (2020).
R. Taniuchi and Pieter Doornenbal, “A new Frontier of unstable doubly magic nuclei,” AAPPS BULLETIN 29, 13–18 (2019).

[Proceedings]
J. Giovinazzo, T. Goigoux, B. Blank, P. Ascher, M. Gerbaux, S. Grevy, T. Kurtukian-Nieto, C. Magron, P. Doornenbal, N. Fukuda,
N. Inabe, G. Kiss, T. Kubo, S. Kubono, S. Nishimura, H. Sakurai, Y. Shimizu, C. Sidong, P. Soderstrom, T. Sumikama, H. Suzuki,
H. Takeda, P. Vi, J. Wu, D. Ahn, J. Agramunt, A. Algora, V. Guadilla, A. Montaner-Piza, A. Morales, S. Orrigo, B. Rubio, Y. Fujita,
M. Tanaka, W. Gelletly, P. Aguilera, F. Molina, F. Diel, D. Lubos, G. de Angelis, D. Napoli, C. Borcea, A. Boso, R. Cakirli, E. Ganioglu,
J. Chiba, D. Nishimura, H. Oikawa, Y. Takei, S. Yagi, K. Wimmer, G. de France, S. Go, and B. Brown, “Two-proton Radioactivity: theInteresting Case of 67 Kr and Further Studies,” Acta Phys. Pol. B 51, 577 (2020).
A. Vitéz-Sveiczer, A. Algora, A. I. Morales, B. Rubio, G. G. Kiss, G. D. Angelis, F. Recchia, S. Nishimura, J. Agramunt, V. Guadilla,
A. Montaner-Pizá, S. E. A. Orrigo, A. Horváth, D. Napoli, S. Lenzi, A. Boso, V. H. phong, J. Wu, P. -A. Söderström, T. Sumikama,
H. Suzuki, H. Takeda, D. S. Ahn, H. Baba, P. Doornenbal, N. Fukuda, N. Inabe, T. Isobe, T. Kubo, S. Kubono, H. Sakurai, Y. Shimizu,
S. Chen, B. Blank, P. Acher, M. Gerbaux, T. Goigoux, J. Giovinazzo, S. Grévy, T. Kurtukián Nieto, C. Magron, W. Gelletly,
Dz. Dombrádi, Y. Fujita, M. Tanaka, P. Aguilera, F. Molina, J. Eberth, F. Diel, D. Lubos, C. Borcea, E. Ganioglu, D. Nishimura,
H. Oikawa, Y. Takei, S. Yagi, W. Korten, G.de. France, P. Davies, J. Liu, J. Lee, T. Lokotko, I. Kojouharov, N. Kurz, and H. Schaﬀner,“Studing the exotic decay 70 Kr → 70 Br∗ ,” Acta Phys. Pol. B 51, 587–594 (2020).
B. Ding, Z. Liu, X. Liu, P. Doornenbal, A. Obertelli, S. Lenzi, P. Walker, L. Chung, B. Linh, G. Authelet, H. Baba, D. Calvet, F. Chateau,
A. Corsi, A. Delbart, J. Gheller, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, M. Niikura,
F. Nowacki, H. Otsu, C. Peron, A. Peyaud, E. Pollacco, J. Rousse, H. Sakurai, M. Sasano, Y. Shiga, S. Takeuchi, R. Taniuchi, T. Uesaka,
H. Wang, K. Yoneda, X. Tang, Y. Lam, T. Huang, M. Sun, W. Zhang, H. Lu, D. Hou, F. Browne, Z. Dombradi, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadynska-Klek, Z. Korkulu, S. Koyama, Y. Kubota, J. Lee, M. Lettmann, R. Lozeva, K. Matsui, T. Miyazaki,
S. Nishimura, C. Louchart, L. Olivier, S. Ota, Z. Patel, E. Sahin, C. Santamaria, C. Shand, P. Soderstrom, G. Stefan, D. Steppenbeck,
T. Sumikama, D. Suzuki, Z. Vajta, V. Werner, J. Wu, Z. Xu, X. Zhou, Y. Zhang, H. Xu, and F. Zhang, “Spectroscopic study in neutronrich Mn isotopes around the N = 40 “Island of Inversion,”” EXON-2018 Proceedings of the International Symposium on Exotic Nuclei“Exotic Nuclei,” 22–34 (2019)
A. Tolosa-Delgado, J. Agramunt, D. Ahn, A. Algora, H. Baba, S. Bae, N. Brewer, C. Bruno, R. Caballero Folch, F. Calvino, P. ColemanSmith, G. Cortes, T. Davinson, I. Dillmann, C. Domingo-Pardo, A. Estrade, N. Fukuda, S. Go, C. Griﬃn, R. Grzywacz, J. Ha, O. Hall,
L. Harkness-Brennan, T. Isobe, D. Kahl, M. Karny, L. Khiem, G. Kiss, M. Kogimtzis, S. Kubono, M. Labiche, I. Lazarus, J. Lee,
J. Liang, J. Liu, G. Lorusso, K. Matsui, K. Miernik, F. Montes, B. Moon, A. Morales, N. Nepal, S. Nishimura, R. Page, V. Phong,Z. Podolyak, V. Pucknell, B. Rasco, P. Regan, A. Riego, B. Rubio, K. Rykaczewski, Y. Saito, H. Sakurai, Y. Shimizu, J. Simpson,
P. Soderstrom, D. Stracener, T. Sumikama, H. Suzuki, J. Tain, M. Takechi, H. Takeda, A. Tarifeno-Saldivia, S. Thomas, P. Woods,
X. Xu, and R. Yokoyama, “Improving nuclear data input for r-process calculations around A ∼ 80,” Springer Proc. Phys. 219, 453–456(2019)
F. Recchia, K. Wimmer, S. Lenzi, S. Riccetto, T. Davinson, A. Estrade, C. Griﬃn, S. Nishimura, F. Nowacki, V. Phong, A. Poves,
P. A. Soderstrom, O. Aktas, M. Alaqueel, T. Ando, H. Baba, S. Bae, S. Choi, P. Doornenbal, J. Ha, L. Harkness-Brennan, T. Isobe,
P. John, D. Kahl, G. Kiss, M. Labiche, K. Matsui, S. Momiyama, D. Napoli, M. Niikura, C. Nita, Y. Saito, H. Sakurai, P. Schrock,
C. Stahl, T. Sumikama, V. Werner, and W. Witt, “Isomer spectroscopy in odd-even Ti isotopes: approaching N = 40,” Acta Phys. Pol.
B 50, 669 (2019).
Y. Watanabe, J. Suwa, K. Nakano, S. Kawase, H. Wang, H. Otsu, H. Sakurai, D. Ahn, M. Aikawa, T. Ando, S. Araki, S. Chen, N. Chiga,
P. Doornenbal, N. Fukuda, T. Isobe, S. Kawakami, T. Kin, Y. Kondo, S. Koyama, S. Kubono, Y. Maeda, A. Makinaga, M. Matsushita,
T. Matsuzaki, S. Michimasa, S. Momiyama, S. Nagamine, T. Nakamura, M. Niikura, T. Ozaki, A. Saito, T. Saito, Y. Shiga, M. Shikata,Y. Shimizu, S. Shimoura, T. Sumikama, P. Soderstrom, H. Suzuki, H. Takeda, S. Takeuchi, R. Taniuchi, Y. Togano, J. Tsubota,
M. Uesaka, Y. Watanabe, K. Wimmer, T. Yamamoto, and K. Yoshida, “Isotopic production cross sections of residual nuclei in protonand deuteron-induced reactions on 91, 92 Y, 92, 93 Zr, and 93, 94 Nb around 100 MeV/nucleon,” CERN Proc. 1, 139–144 (2019).
X. Sun, H. Wang, H. Otsu, H. Sakurai, D. Ahn, M. Aikawa, P. Doornenbal, N. Fukuda, T. Isobe, S. Kawakami, S. Koyama, T. Kubo,
S. Kubono, G. Lorusso, Y. Maeda, A. Makinaga, S. Momiyama, K. Nakano, M. Niikura, Y. Shiga, P. A. Soderstrom, H. Suzuki,
H. Takeda, S. Takeuchi, R. Taniuchi, Y. Watanabe, Y. Watanabe, H. Yamasaki, and K. Yoshida, “Cross section measurements in thereactions of 136 Xe on proton, deuteron and carbon at 168 MeV/u,” CERN Proc. 1, 153–158 (2019).
S. Kubono, T. Kawabata, N. Iwasa, J. J. He, and S. Q. Hou, “Experimental Challenge to the Cosmological Li Problem,” Proc. Int.
Conference on Nuclei in the Cosmos XV, ed. A. Formicola, et al., Springer Proceedings in Physics 219, 45–52 (2019).
S. Hayakawa, K. Abe, O. Beliuskina, S. M. Cha, K. Y. Chae, S. Cherubini, P. Figuera, Z. Ge, M. Gulino, J. Hu, A. Inoue, N. Iwasa,
D. Kahl, A. Kim, D. H. Kim, G. G. Kiss, S. Kubono, M. La Cognata, L. Lamia, M. Lattuada, E. J. Lee, J. Y. Moon, Sara Palmerini,
C. Parascandolo, S. Y. Park, D. Pierroutsakou, Rosario Gianluca Pizzone, G. G. Rapisarda, S. Romano, H. Shimizu, C. Spitaleri,
Xiaodong Tang, O. Trippella, Aurora Tumino, P. Vi, H. Yamaguchi, L. Yang, and N. T. Zhang “Cross section measurements of the7
Be(n, p)7 Li and the 7 Be(n, α)4 He reactions covering the big-bang nucleosynthesis energy range by the trojan horse method at CRIB,”
Proc. Int. Conference on Nuclei in the Cosmos XV, ed. A. Formicola, et al., Springer Proceedings in Physics 219, 33–38 (2019).

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L. Lamia, C. Spitaleri, M. Mazzocco, S. Hayakawa, C. A. Bertulani, A. Boiano, C. Boiano, Carlo Broggini, Antonio Caciolli,
Rosanna Depalo, F. Galtarossa, G. L. Guardo, M. Gulino, S. Kubono, M. La Cognata, M. La Commara, G. La Rana, M. Lattuada,
Roberto Menegazzo, A. Pakou, C. Parascandolo, D. Piatti, D. Pierroutsakou, Rosario Gianluca Pizzone, S. Romano, G. G. Rapisarda,
M. L. Sergi, O. Sgouros, F. Soramel, V. Soukeras, E. Strano, D. Torresi, Aurora Tumino, H. Yamaguchi, F. L. Villante, and G. L. Zhang“The Cosmologically Relevant 7 Be(n, α)4 He Reaction in View of the Recent THM Investigations,” Proc. Int. Conference on Nuclei in
the Cosmos XV, ed. A. Formicola, et al., Springer Proceedings in Physics 219, 53–56 (2019).
H. Shimizu, D. Kahl, H. Yamaguchi, K. Abe, O. Beliuskina, S. M. Cha, K. Y. Chae, A. A. Chen, Z. Ge, S. Hayakawa, N. Imai, N. Iwasa,
A. Kim, D. H. Kim, M. J. Kim, S. Kubono, M. S. Kawag, J. Liang, J. Y. Moon, S. Nishimura, S. Oka, S. Y. Park, A. Psaltis, T. Teranishi,
Y. Ueno, and L. Yang, “Study on 26m Al(p, γ) reaction at the SNe temperature,” JPS Conf. Proc. 31, 011073 (2020).
S. Hayakawa, M. La Cognata, L. Lamia, H. Shimizu, L. Yang, H. Yamaguchi, K. Abe, O. Beliuskina, S. M. Cha, K. Y. Chae, S. Cherubini,
P. Figuera, Z. Ge, M. Gulino, J. Hu, A. Inoue, N. Iwasa, D. Kahl, A. Kim, D. H. Kim, G. Kiss, S. Kubono, M. La Commara,
M. Lattuada, E. J. Lee, J. Y. Moon, S. Palmerini, C. Parascandolo, S. Y. Park, D. Pierroutsakou, R. G. Pizzone, G. G. Rapisarda,
S. Romano, C. Spitaleri, X. D. Tang, O. Trippella, A. Tumino, P. Vi, and N. T. Zhang, “Experimental study on the 7 Be(n, p)7 Li and the7Be(n, α)4 He reactions for cosmological lithium problem,”JPS Conf. Proc. 31, 011036 (2020).

Presentations[International conferences/workshops]
H. Sakurai (invited), “In-flight radioactive isotope beam facilities and nuclear physics at RIKEN,” The First African Nuclear Physics
Conference (ANPC), Kruger, South Africa, July 1–5, 2019.
S. Nishimura (invited), “r-process studies at RIBF,” Nuclear and astrophysics aspects for the rapid neutron capture process in the era ofmultimessenger observations, ECT∗ , Trento, Italy, July 1–5, 2019.
S. Nishimura (invited), “Decay properties of exotic nuclei” China-Japan Collaboration Workshop on Nuclear Mass and Life for Unraveling
Mysteries of R-process, ITP-CAS, Beijing, China, October 9–13, 2019.
S. Nishimura (invited), “Ukakuren” JINA-CEE IReNA/NAOJ Workshop, National Astronomy Observation of Japan, Mitaka, Japan,
December 3-4 (2019).
T. Isobe (poster), “Measurement of Th-229 low lying isomeric state with MRTOF+TES system at RIKEN-RIBF,” 18th International
Workshop on Low Temperature Detectors (LTD18), Milano, Italy, July 22–26, 2019.
T. Isobe (invited), “Latest update on RIKEN facilities,” 9th International Symposium on Nuclear Symmetry Energy (NuSym2019), Danan,
Vietnam, September 30–October 4, 2019.
T. Isobe (oral), “Experimental study of hydrogen isotopes production in Sn+Sn RI collisions at 270 AMeV,” 9th International Symposium
on Nuclear Symmetry Energy (NuSym2019), Danan, Vietnam, September 30–October 4, 2019.
P. Doornenbal (invited), “Structure of exotic Calcium and Nickel isotopes,” 14th Asia Pacific Physics Conference, Kuching, Malaysia,
November 17–22, 2019.
P. Doornenbal (invited), “Exploring the terra incognita of exotic nuclei at RIKEN: past achievements and future endeavors,” VINANST-13,
Reu Island, Vietnam, August 7–9, 2019.
P. Doornenbal (invited), “Towards high-resolution in-beam Gamma-ray spectroscopy at the RIBF,” 27th International Nuclear Physics
Conference (INPC), Glasgow, UK, July 29–August 2, 2019.
P. Doornenbal (invited), “In-beam gamma-ray spectroscopy at RIKEN,” 1st African Nuclear Physics Conference (ANPC), Kruger National Park, South Africa, July 1–5, 2019.
P. Doornenbal (oral), “High resolution spectroscopy of 78 Ni,” High Resolution Gamma-ray Spectrosocpy at the RIBF Workhsop, Darmstadt, Germany, April 10–12, 2019.
P. Doornenbal (oral), “Technical Considerations,” High Resolution Gamma-ray Spectrosocpy at the RIBF Workhsop, Darmstadt, Germany, April 10–12, 2019.
D. Suzuki (invited), “Present and future of in-beam spectroscopy at RIBF,” Workshop on RI-beam Spectroscopy by Innovative Gaseous
Active Targets, Osaka, Japan, December 19–20, 2019.
D. Suzuki (invited), “Present and future of in-beam spectroscopy at RIBF,” Workshop on RI-beam Spectroscopy by Innovative Gaseous
Active Targets, Osaka, Japan, December 19–20, 2019.
D. Suzuki (oral), “Coulomb and quantum bubbles in heavy nuclei,” High Resolution Gamma-Ray Spectroscopy at the RIBF, Darmstadt,
Germany, April 10–12, 2019.
D. Suzuki (oral), “rp-process study at OEDO,” OEDO collaboration workshop, Wako, Japan, September 2, 2019.
D. Suzuki (oral), “Recent results from SUNFLOWER and future perspectives,” JSPS/NRF/NSFC A3 Foresight Program “Nuclear Physics
in the 21st Century” Joint Kickoﬀ Meeting, Kobe, Japan, December 6–7, 2019.
D. Suzuki (invited), “Present and future of in-beam spectroscopy at RIBF,” Workshop on RI-beam Spectroscopy by Innovative Gaseous
Active Targets, Osaka, Japan, December 19–20, 2019.
D. Suzuki (invited), “Present and future of in-beam spectroscopy at RIBF,” Workshop on RI-beam Spectroscopy by Innovative Gaseous
Active Targets, Osaka, Japan, December 19–20, 2019.
D. Suzuki (oral), “Coulomb and quantum bubbles in heavy nuclei,” High Resolution Gamma-Ray Spectroscopy at the RIBF, Darmstadt,
Germany, April 10–12, 2019.
D. Suzuki (oral), “rp-process study at OEDO,” OEDO collaboration workshop, Wako, Japan, September 2, 2019.
W. Horiuchi, S. Hatakeyama, A. Kohama (oral), “Nuclear “diﬀuseness” probed by proton-nucleus diﬀraction,” The 27th International- 254 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Physics Conference (INPC 2019), Glasgow, UK, July 29–August 2, 2019. (INPC 2019)
S. Kubono (invited), “Heavy element synthesis under explosive burning on neutron stars,” The 10th European Summer School on Experimental Nuclear Astrophysics Catania, INFN-LNS, June 16–23, 2019.
S. Kubono (invited), “Experimental approach to explosive H-burning in X-ray bursts and SNeII,” Workshop on origin of Elements andCosmic Evolution: From Big-Bang to Supernovae and Mergers, Beihang University, China, November 27–29, 2019.
K. Asahi (invited), “Experiment on nuclear EDMs,” KEK Workshop on Nucleon EDMs and Spin Structure 2020, KEK Tokai Campus,
Tokai, Ibaraki, Japan, January 11, 2020.
R. Taniuchi (oral), “Approaching the fifth island of inversion from the north” High Resolution Gamma-Ray Spectroscopy at the RIBF, TU
Darmstadt, Germany, April 10–12, 2019.
R. Taniuchi (oral), “In-beam gamma-ray spectroscopy of 78 Ni reveals its doubly magic character,” 27th International Nuclear Physics
Conference (INPC 2019), Glasgow, United Kingdom, July 29–August 2, 2019.
R. Taniuchi (oral), “Quest for shell quenching of N = 50 in doubly magic 78 Ni” 8th SUNFLOWER Workshop/HiCARI Workshop, Osaka,
September 26–28, 2019.
V. Phong (oral), “β-decay measurements of very neutron-rich isotopes around Mass A = 130 within the BRIKEN project at RIBF,” 15th
International Symposium on Origin of Matter and Evolution of Galaxies (OMEG15), Kyoto, Japan, July 2–5, 2019.
V. Phong (oral), “Measurement of very neutron-rich beta delayed neutron emitters around mass A = 130 relevant to the astrophysicalr-process,” 9th International Symposium on Nuclear Symmetry Energy (NuSYM2019), Danang, Vietnam, September 30–October 4,
2019.
H. Shimizu (poster), “Study on 26m Al(p, γ) reaction at the SNe temperature,” Symposium on Origin of Matter and Evolution of Galaxies(OMEG15), Kyoto, Japan, July 2–5, 2019.
H. Shimizu (poster), “Isomeric 26 Al beam production with CRIB,” Nuclear Physics School For Young Scientists (NUSYS-2019), Lanzhou,
China, August 12–17, 2019.
T. Koiwai (oral), “Single-particle structure of 55 Ti and 57 Ti,” Workshop on high-resolution gamma-ray spectroscopy at the RIBF, Darmstadt, Germany, April 2019
T. Koiwai (oral), “In-beam γ-ray spectroscopy of 55 K and 55 Ca via neucleon knockout reactions,” International Nuclear Physics Conference (INPC 2019), Glasgow, UK, July–Augsut 2019
T. Koiwai (oral), “N = 34 beyond 54 Ca: Single-particle structure of 55, 57 Ti,” 8th SUNFLOWER Workshop and HiCARI Workshop (JSPS
A3Foresight), Osaka, Japan, August 2019.

[Domestic conferences/workshops]ᓎҪതّʢট଴ߨԋʣ,ʮRIBF Ͱͷ֩෺ཧ‫ڀݚ‬ʯ, ‫ڀݚ‬ձʮγϛϡϨʔγϣϯʹΑΔӉ஦ͷ‫ج‬ຊ๏ଇͱਐԽͷղ໌ʹ޲͚ͯʢQUCS2019ʣʯ,‫౎ژ‬େֶ‫ૅج‬෺ཧֶ‫ॴڀݚ‬, ‫౎ژ‬, 2019 ೥ 12 ݄.
੢ଜढ़ೋʢ‫ޱ‬಄ൃදʣ, ʮr ϓϩηεͷ‫ڀݚ‬: ࣮‫ݧ‬త‫ͱূݕ‬௅ઓʯ, ‫ڀݚ‬ձʮ‫֩ࢠݪ‬෺ཧͰͭΉ͙ r ϓϩηεʯ, ‫౎ژ‬େֶ‫ૅج‬෺ཧֶ‫ݚ‬‫ॴڀ‬, ‫౎ژ‬, 2019 ೥ 5 ݄ 22–24 ೔.
P. Doornenbal (invited), “Recent results from SUNFLOWER and future plans,” RIBF Week, Wako, Japan, September 2–4, 2019.
P. Doornenbal (invited), “Results from SEASTAR III,” SAMURAI Workshop, Tokyo, Japan, August 30–31, 2019.
P. Doornenbal (oral), “Sunflower Status,” SUNFLOWER/HiCARI Workshop, Osaka, Japan, August 26–28, 2019.
P. Doornenbal (invited), “Probing the Nuclear Shell Closures far oﬀ Stability with In-Beam Gamma-Ray Spectroscopy,” JPS Spring
Meeting, Kyushu, Japan, March 14–17, 2019.
ᴳ‫ޱ‬༤ਔʢ‫ޱ‬಄ൃදʣ, ງ಺ব, খᖛ༸ԝ, ʮ൓ཅࢠ-‫ࢄ֩ࢠݪ‬ཚʹΑΔ‫ر‬ബ֩ີ౓ྖҬͷ୳ࡧʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ౦ࢁΩϟϯύε, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16 ೔–20 ೔.
F. Browne (oral), “Coulomb excitation study of Se isotopes beyond N = 50,” 8th SUNFLOWER Workshop/HiCARI Workshop (JSPS
A3Foresight), Osaka, Japan, August 26–28, 2019.
୩಺ྏʢট଴ߨԋʣ, ʮ֩ม‫ʹܗ‬ରͯ͠ೋॏด֪Λ‫࣋͢ݎ‬Δ 78Niʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶʢΦϯϥΠϯ։࠵ʣ,2020 ೥ 3 ݄ 16–19 ೔.
Ѵ ߞҰ࿠ʢট଴ߨԋʣ, ʮ‫ࢠݪ‬ͷ EDM ͱ࣌ؒ൓సରশੑͷഁΕ—൓࣓ੑ‫ࢠݪ‬ͷ EDM Λத৺ʹʯ, ిࢠ EDM ‫ڀݚ‬ձ, ౦‫ژ‬େֶۨ৔Ωϟϯύε, ໨ࠇ, 2019 ೥ 12 ݄ 11 ೔.

[Seminars]
T. Isobe, “Overview of the RI Beam Facility (RIBF),” CNS Summer School 2019 (CNSSS19), Nishina Hall Riken Wako, August 21–27,
2019.
T. Isobe, “Experimental study of asymmetric dense nuclear matter Equation Of State by using heavy RI collisions at RIBF-SπRIT,” CNS
Summer School 2019 (CNSSS19), Nishina Hall Riken Wako, August 21–27, 2019.
S. Kubono, “Special lectures on nuclear astrophysics,” Department of Physics, Hong Kong University, April 15–18, 2019.
K. Asahi, “Electric dipole moments of diamagnetic atoms—Present status of experiments,” CNS Seminar, Hongo, Tokyo, Japan, June 13,
2019.
R. Taniuchi, “78 Ni revealed as a doubly magic stronghold against nuclear deformation,” 276th RIKEN RIBF Nuclear Physics Seminar,
Saitama, Japan, May 28, 2019.
R. Taniuchi, “In-beam gamma-ray spectroscopy of 78 Ni revealed its double magicity and shape-coexistence,” The RIBF Users Group
Thesis Award lecture, RIBF Week 2019, Saitama, September 3, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

AwardsP. Doornenbal, RIKEN BAIHO Award 2020, Achievement: In-beam γ-ray spectroscopy of the neutron-rich doubly-magic nucleus 78 Ni
R. Taniuchi, The RIBF Users Group Thesis Award, September 3, 2019.
୩಺ྏ, ୈ 14 ճʢ2020 ೥ʣ೔ຊ෺ཧֶձएख঑ྭ৆, 2020 ೥ 3 ݄ 18 ೔.
୩಺ྏ, ୈ 26 ճ‫֩ࢠݪ‬ஊ࿩ձ ৽ਓ৆, 2020 ೥ 3 ݄ 18 ೔.
V. Phong, ANPhA(and AAPPS DNP) award for Young Scientists at 9th International Symposium on Nuclear Symmetry Energy(NuSYM2019): 2nd prize.

Press releasesʮຐ๏਺‫ࣈۚʹڀݚ‬ౝ—͍ͭʹதੑࢠա৒ͳχοέϧ‫֩ࢠݪ‬ͷೋॏຐ๏ੑʹ݁࿦—ʯ, 2019 ೥ 5 ݄ 2 ೔.
ʮ৽ຐ๏਺ 34 ͷ৽ͨͳূ‫—ڌ‬தੑࢠϊοΫΞ΢τ൓ԠͰ୳ΔΧϧγ΢Ϝ-54 ͷด֪ߏ଄—ʯ, 2019 ೥ 10 ݄ 18 ೔.
ʮ‫ʹܹٸ‬๲ΕΔ‫—֩ࢠݪ‬Χϧγ΢ϜಉҐମͰ‫͔ͨͬͭݟ‬ҟৗͳ֩൒‫૿ܘ‬େ‫ݱ‬৅—ʯ, 2020 ೥ 3 ݄ 13 ೔.

Outreach activitiesᓎҪതّ, ʮ‫ݩ‬ૉͷਐԽͱม‫׵‬ʯ, 2019 ೥౓Ѷ԰ެຽ‫ؗ‬αΠΤϯεߨ࠲, 2019 ೥ 4–6 ݄.
ү෦஧ত, ʮՊֶऀʹͳΔͱ͍͏ࣄʙੈք࠷ઌ୺ͷ‫ͱڀݚ‬ະདྷʙʯ, ࡉాֶԂߨԋձ, ࡉాֶԂߴ౳ֶߍ, ࢤ໦, 2019 ೥ 6 ݄ 24 ೔.

Others[Software package]
A. Kohama, K. Iida, K. Oyamatsu, H. Iwase, Release of “kurotama0” update (ver. 3.0), Contribution of PHITS update to ver. 3.20,
March 2020.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Spin isospin Laboratory
1. Abstract
The Spin Isospin Laboratory pursues research activities putting primary focus on interplay of spin and isospin in exotic nuclei.
Understanding nucleosyntheses in the universe, especially those in r- and rp-processes is another big goal of our laboratory.
Investigations on isospin dependences of nuclear equation of state, spin-isospin responses of exotic nuclei, occurrence of various
correlations at low-densities, evolution of spin-orbit coupling are main subjects along the line. We are leading a mass measurement
project with the Rare RI Ring project, too. Through the experimental studies, we will be able to elucidate a variety of nuclear
phenomena in terms of interplay of spin and isospin, which will in turn, lead us to better understanding of our universe.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Direct reaction studies of neutron-matter equation of state
Study of spin-isospin responses with RI-beams
R-process nucleosynthesis study with heavy-ion storage ring
Application of spin-polarization technique to RI-beam experiments and other fields
Development of special targets for RI-beam experiments

3. Summary of Research Activity(1) Direct reaction studies of neutron matter equation of state
Direct reactions induced by light-ions serve as powerful tools to investigate various aspects of nuclei. We are advancing experimental programs to explore equation of state of neutron matter, via light-ion induced reactions with RI-beams.
(1-1) Determination of a neutron skin thickness by proton elastic scattering
A neutron skin thickness is known to have strong relevance to asymmetry terms of nuclear equation of state, especially to aterm proportional to density. The ESPRI project aims at determining density distributions in exotic nuclei precisely by proton elastic
scattering at 200–300 MeV/nucleon. An experiment for 132 Sn that is a flagship in this project has been successfully performed.
(1-2) Asymmetry terms in nuclear incompressibility
Nuclear incompressibility represents stiﬀness of nuclear matter. Incompressibility of symmetric nuclear matter is determined
to be 230 ± 20 MeV, but its isospin dependence still has a large uncertainty at present. A direct approach to the incompressibilityof asymmetric nuclear matter is an experimental determination of energies of isoscalar giant monopole resonances (GMR) in heavy
nuclei. We have developed, in close collaboration with Center for Nuclear Study (CNS) of University of Tokyo, an active gas target
for deuteron inelastic scattering experiments to determine GMR energies. The active gas target has been already tested with oxygen
and xenon beams at HIMAC and finally has been applied to a 132 Sn experiment at RIBF.
(1-3) Multi-neutron and α-cluster correlations at low densities
Occurrences of multi-neutron and α-cluster correlations are other interesting aspects of nuclear matter and define its low-density
behavior. The multi-neutron and α-cluster correlations can be investigated with the large-acceptance SAMURAI spectrometer. The
SAMURAI has been already applied to experiments to explore light neutron-rich nuclei close to the dripline. We plan to reinforce
experimental capabilities of the SAMURAI by introducing advanced devices such as MINOS (Saclay) and NeuLAND (GSI).
(1-4) Fission barrier heights in neutron-rich heavy nuclei
The symmetry energy has a strong influence on fission barrier heights in neutron-rich nuclei. Knowledge on the fission barrierheights, which is quite poor at present, is quite important for our proper understanding on termination of the r-process. We are planningto perform, in collaboration with the TU Munich group, (p, 2p)-delayed fission experiments at the SAMURAI to determine the fission
barrier heights in neutron-rich nuclei in Pb region.
(2) Study of spin-isospin responses with RI-beams
The study of spin-isospin responses in nuclei forms one of the important cores of nuclear physics. A variety of collective states,for example isovector giant dipole resonances, isobaric analogue states, Gamow-Teller resonances, have been extensively studied byuse of electromagnetic and hadronic reactions from stable targets.
The research opportunities can be largely enhanced with light of availabilities of radioactive isotope (RI) beams and of physics of
unstable nuclei. There are three possible directions to proceed. The first direction is studies of spin-isospin responses of unstable nuclei
via inverse-kinematics charge exchange reactions. A neutron-detector array WINDS has been constructed, under a collaboration of
CNS, Tokyo and RIKEN, for inverse kinematics (p, n) experiments at the RI Beam Factory. We have already applied WINDS to the(p, n) experiments for 12 Be, 132 Sn and plan to extend this kind of study to other exotic nuclei.
The second direction is studies with RI-beam induced charge exchange reaction. RI-beam induced reactions have unique properties which are missing in stable-beam induced reactions and can be used to reach the yet-to-be-discovered states. We have constructed
the SHARAQ spectrometer and the high-resolution beam-line at the RI Beam Factory to pursue the capabilities of RI-beam induced
reactions as new probes to nuclei. One of the highlights is an observation of β+ type isovector spin monopole resonances (IVSMR) in
208
Pb and 90 Zr via the (t, 3 He) reaction at 300 MeV/nucleon.
The third direction is studies of neutron- and proton-rich nuclei via stable-beam induced charge exchange reactions, which is
conducted under collaboration with Research Center for Nuclear Physics (RCNP), Osaka University. We have performed the double- 257 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

charge exchange 12 C(18 O, 18 Ne) 12 Be reaction at 80 MeV/nucleon to investigate structure of a neutron-rich 12 Be nucleus. Peaks corresponding to ground and excited levels in 12 Be have been clearly observed. Another double charge exchange reaction, (12 C, 12 Be(0+2 ))are being used to search for double Gamow-Teller resonances.
(3) R-process nucleosynthesis study with heavy-ion storage ring
Most of the r-process nuclei become within reach of experimental studies for the first time at RI Beam Factory at RIKEN. The
Rare RI Ring at RIBF is the unique facility with which we can perform mass measurements of r-process nuclei. Construction of theRare RI Ring started in FY2012 in collaboration with Tsukuba and Saitama Universities. A major part of the ring has been completed
and the commissioning run is planned in FY2014.
We are planning to start precise mass measurements of r-process nuclei soon. A series of experiments will start with nuclei in the
A = 80 region and will be extended to heavier region.
(4) Application of spin-polarization technique to RI-beam experiments and other fields
A technique to produce nuclear polarization by means of electron polarization in photo-excited triplet states of aromatic molecules
can open new applications. The technique is called “Tripletd-DNP.” A distinguished feature of Triplet-DNP is that it works under alow magnetic field of 0.1–0.7 T and temperature higher than 100 K, which exhibits a striking contrast to standard dynamic nuclear
polarization (DNP) techniques working in extreme conditions of several Tesla and sub-Kelvin.
We have constructed a polarized proton target system for use in RI-beam experiments. Recent experimental and theoretical studies
have revealed that spin degrees of freedom play a vital role in exotic nuclei. Tensor force eﬀects on the evolution of shell and possible
occurrence of p-n pairing in the proton-rich region are good examples of manifestations of spin degrees of freedom. Experimentswith the target system allow us to explore the spin eﬀects in exotic nuclei. It should be noted that we have recently achieved a proton
polarization of 40% at room temperature in a pentacene-d14 doped p-terphenyl crystal.
Another interesting application of Triplet-DNP is sensitivity enhancement in NMR spectroscopy of biomolecules. We started a
new project to apply the Triplet-DNP technique to study protein-protein interaction via two-dimensional NMR spectroscopy, in close
collaboration with biologists and chemists.
(5) Development of special targets for RI-beam experiments
For the research activities shown above, we are developing and hosting special targets for RI-beam experiments listed below:(a) Polarized proton target (described in (4))(b) Thin solid hydrogen target(c) MINOS (developed at Saclay and hosted by the Spin Isospin Laboratory)

Members
Director
Tomohiro UESAKA
Research/Technical Scientists
Masaki SASANO (Senior Research Scientist)
Ken-ichiro YONEDA (Senior Research Scientist)

Juzo ZENIHIRO (Senior Research Scientist)
Sarah NAIMI (Research Scientist)

Contract Researchers
Takeshi INOUE

Kenichiro TATEISHI

Postdoctoral Researcher
Junki TANAKA
Junior Research Associates
Tomoya HARADA

Shoichiro MASUOKAInternational Program Associates
Siwei HUANG (Peking Univ.)
Alexandra-Ionela STEFANESCU (Univ. of Bucharest)

Ionut-Catalin STEFANESCU (Univ. of Bucharest)
Hongfu LI (IMP, CAS)

Research Consultants
Harutaka SAKAGUCHI (Osaka Univ.)
Yasuyuki SUZUKI (Niigata Univ.)

Kazuko TANABE (Otsuma Women’s Univ.)

Senior Visiting Scientist
Hiroyuki SAGAWA (Univ. of Aizu)- 258 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Visiting Scientists
Hidetoshi AKIMUNE (Konan Univ.)
Didier BEAUMEL (CNRS IPN Orsay)
Konstanze BORETZKY (GSI)
Christoph CAESAR (GSI)
Anna CORSI (CEA Saclay)
Zsolt DOMBRADI (ATOMKI)
Zoltan ELEKES (ATOMKI)
Zsolt FULOP (ATOMKI)
Tatsuya FURUNO (Osaka Univ.)
Igor GASPARIC (Rudjer Boskovic Inst.)
Zhuang GE (IMP, CAS)
Alain GILLIBERT (CEA Saclay)
Valdir GUIMARAES (Inst. de Fisica da Univ. de Sao Paulo)
Zoltan HALASZ (ATOMKI)
Matthias HOLL (TRIUMF)
Kaori KAKI (Shizuoka Univ.)
Takahiro KAWABATA (Kyoto Univ.)
Yuma KIKUCHI (NIT, Tokuyama College)
Yosuke KONDO (Tokyo Tech.)
Zeren KORKULU (ATOMKI)
Attila KRASZNAHORKAY (ATOMKI)
Dorottya KUNNE SOHLER (ATOMKI)
Istvan KUTI (ATOMKI)
Valerie LAPOUX (CEA Saclay)
Yury LITVINOV (GSI)
Hongna LIU (TU Darmstadt)

Yohei MATSUDA (Tohoku Univ.)
Kenjiro MIKI (Tohoku Univ.)
Tetsuaki MORIGUCHI (Tsukuba Univ.)
Momo MUKAI (Tsukuba Univ.)
Takashi NAKAMURA (Tokyo Tech.)Alexandre OBERTELLI (TU Darmstadt)
Kazuyuki OGATA (Osaka Univ.)
Valerii PANIN (CEA Saclay)
Emanuel POLLACCO (CEA Saclay)
Kimiko SEKIGUCHI (Tohoku Univ.)
Haik SIMON (GSI)
Laszlo STUHL (ATOMKI)
Baohua SUN (Beihang Univ.)
Yelei SUN (TU darmstadt)
Shinji SUZUKI (Chinese Academy of Sci.)
Satoru TERASHIMA (Beihang Univ.)
Hans Toshihide TOERNQVIST (TU Darmstadt)
Yasuhiro TOGANO (Rikkyo Univ.)
Takashi WAKUI (QST)
He WANG (Tokyo Tech.)Takayuki YAMAGUCHI (Saitama Univ.)
Nobuhiro YANAI (Kyushu Univ.)
Zaihong YANG (Osaka Univ.)
Juzo ZENIHIRO (Kyoto Univ.)
Yuhu ZHANG (Chinese Academy of Sci.)

Visiting Technicians
Gilles AUTHELET (CEA Saclay)
Denis CALVET (CEA Saclay)
Alain DELBART (CEA Saclay)
Jean-Marc GHELLER (CEA Saclay)
Arnaud GIGANON (CEA Saclay)

Clement HILAIRE (CEA Saclay)
Daniel KOERPER (GSI)
Cedric PERON (CEA Saclay)
Jean-Yves ROUSSE (CEA Saclay)
Olivier TELLIER (CEA Saclay)

Student Trainees
Paul E. ANDRE (CEA Saclay)
Takanobu DOI (Kyoto Univ.)
Wenbo DOU (Saitama Univ.)
Naoki EBINA (Tokyo Tech.)
Shiyo EN’YO (Kyoto Univ.)
Yuuki FUJII (Tokyo Tech.)
Yuki FUJIKAWA (Kyoto Univ.)
Saiya FUJIWARA (Kyushu Univ.)
Jian GAO (Peking Univ.)
Daiki HAMAKAWA (Saitama Univ.)
Yuya HAMANO (Kyushu Univ.)
Yuto HIJIKATA (Kyoto Univ.)
Yuma HIRAI (Kyushu Univ.)
Shun HOSOI (Saitama Univ.)Nancy Anne Paul HUPIN (Univ. of Paris-Saclay)
Kento INABA (Kyoto Univ.)
Yasuto INADA (Saitama Univ.)
Daiki INOMOTO (Kyushu Univ.)
Minami INOUE (Tohoku Univ.)
Shunya ISHIDA (Tohoku Univ.)
Leo KAGESAWA (Tsukuba Univ.)
Daisuke KAJIKI (Saitama Univ.)
Hina KASAHARA (Kyushu Univ.)
Kenta KAWAHARA (Tohoku Univ.)
Yusuke KAWASHIMA (Kyushu Univ.)

Sho KITAYAMA (Tohoku Univ.)
Shuhei KIYOTAKE (Univ. of Miyazaki)
Hironori KOUNO (Kyushu Univ.)
Taishi KUBO (Kyushu Univ.)
Atsushi KURIHARA (Tokyo Tech.)
Hayato KUROSAWA (Tohoku Univ.)
Christopher LEHR (TU Darmstadt)
Pengjie LI (The Univ. of Hong Kong)
Zanetti LORENZO (TU Darmstadt)
Ryu MAEDA (Tohoku Univ.)
Riku MATSUMURA (Saitama Univ.)
Hareru MIKI (Tokyo Tech.)
Midori MIWA (Saitama Univ.)
Motoki MURATA (Kyoto Univ.)
Anna NAKAGAWA (Tohoku Univ.)
Shinnosuke NAKAI (Tohoku Univ.)
Mio NISHIMURA (Rikkyo Univ.)
Toui NISHIMURA (Univ. of Miyazaki)
Kotaro NONAKA (Univ. of Miyazaki)
Kyoko NOSAKA (Tohoku Univ.)
Shintaro OKAMOTO (Kyoto Univ.)
Su-yeon PARK (Ewha Womans Univ.)
Atsumi SAITO (Tokyo Tech.)
Yuko SAITO (Tohoku Univ.)
Daisuke SAKAI (Tohoku Univ.)- 259 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Shigehito SAKAKI (Kyushu Univ.)
Kosuke SAKANASHI (Osaka Univ.)
Akane SAKAUE (Kyoto Univ.)
Mamoru SAKAUE (Saitama Univ.)
Tetsuro SHIMADA (Tokyo Tech.)
Dora SZALKAI (Eotvos Lorand Univ.)
Kohei TAKAHASHI (Tokyo Tech.)
Yuta UTSUKI (Tohoku Univ.)

Vadim WAGNER (TU Darmstadt)
Atomu WATANABE (Tohoku Univ.)
Kohei YAMAMOTO (Tohoku Univ.)
Shinpei YAMANAGA (Univ. of Miyazaki)
Akira YASUDA (Tokyo Tech.)
Kenjiro YOKOTA (Saitama Univ.)
Yuuki YOSHITOME (Tokyo Tech.)
Jianwei ZHAO (Beihang Univ.)

Interns
Maruf ALI (Univ. of Surrey)
Richard CRANE (Univ. of Surry)George W. G. W. HUDSON-CHANG (Univ. of Surrey)

Assistants
Emiko ISOGAI
Asako TAKAHASHI

Yuri TSUBURAI

List of Publications & Presentations
Publications[Original papers]
Z. Elekes, Á. Kripkó, D. Sohler, K. Sieja, K. Ogata, K. Yoshida, P. Doornenbal, A. Obertelli, G. Authelet, H. Baba, D. Calvet, F. Château,
A. Corsi, A. Delbart, J. -M. Gheller, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, H. Otsu,
C. Péron, A. Peyaud, E. C. Pollacco, J. -Y. Roussé, H. Sakurai, C. Santamaria, Y. Shiga, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang,
K. Yoneda, F. Browne, L. X. Chung, Zs. Dombrádi, F. Flavigny, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadyńska-Klȩk, Z. Korkulu,
S. Koyama, Y. Kubota, J. Lee, M. Lettmann, C. Louchart, R. Lozeva, K. Matsui, T. Miyazaki, M. Niikura, S. Nishimura, L. Olivier,S. Ota, Z. Patel, E. Sahin, C. Shand, P. -A. Söderström, I. Stefan, D. Steppenbeck, T. Sumikama, D. Suzuki, Zs. Vajta, V. Werner, J. Wu,
and Z. Xu, “Nuclear structure of 76 Ni from the (p, 2p) reaction,” Phys. Rev. C 99, 014312 (2019).
A. I. Chilug, V. Panin, D. Tudor, L. Trache, I. C. Stefanescu, A. E. Spiridon, A. Saastamoinen, Z. Halasz, T. Motobayashi, T. Uesaka,
K. Yoneda, H. Otsu, “Study of the 9C breakup through NP1412-SAMURAI29R1 experiment,” AIP Conf. Proc. 2076, 060001 (2019).
Z. H. Yang, F. M. Marqués, N. L. Achouri, D. S. Ahn, T. Aumann, H. Baba, D. Beaumel, M. Böhmer, K. Boretzky, M. Caamaño, S. Chen,
N. Chiga, M. L. Cortés, D. Cortina, P. Doornenbal, C. A. Douma, F. Dufter, J. Feng, B. Fernández-Dom’ınguez, Z. Elekes, U. Forsberg,
T. Fujino, N. Fukuda, I. Gašparić, Z. Ge, R. Gernhäuser, J. M. Gheller, J. Gibelin, A. Gillibert, B. M. Godoy, Z. Halász, T. Harada,
M. N. Harakeh, A. Hirayama, S. W. Huang, N. Inabe, T. Isobe, J. Kahlbow, N. Kalantar-Nayestanaki, D. Kim, S. Kim, M. A. Knösel,
T. Kobayashi, Y. Kondo, P. Koseoglou, Y. Kubota, I. Kuti, C. Lehr, P. J. Li, Y. Liu, Y. Maeda, S. Masuoka, M. Matsumoto, J. Mayer,
H. Miki, M. Miwa, I. Murray, T. Nakamura, A. Obertelli, N. Orr, H. Otsu, V. Panin, S. Park, M. Parlog, S. Paschalis, M. Potlog,
S. Reichert, A. Revel, D. Rossi, A. Saito, M. Sasano, H. Sato, H. Scheit, F. Schindler, T. Shimada, Y. Shimizu, S. Shimoura, I. Stefan,
S. Storck, L. Stuhl, H. Suzuki, D. Symochko, H. Takeda, S. Takeuchi, J. Tanaka, Y. Togano, T. Tomai, H. T. Törnqvsit. J. Tscheuschner,
T. Uesaka, V. Wagner, K. Wimmer, H. Yamada, B. Yang, L. Yang, Y. Yasuda, K. Yoneda, L. Zanetti, and J. Zenihiro, “Study of multineutron systems with SAMURAI spectrometer,” Springer Proc. Phys. 238, 529–534 (2020).
V. P. Ladygin, A. V. Averyanov, E. V. Chernykh, D. Enache, Yu. V. Gurchin, A. Yu. Isupov, M. Janek, J. -T. Karachuk, A. N. Khrenov,
D. O. Krivenkov, P. K. Kurilkin, N. B. Ladygina, A. N. Livanov, O. Mezhenska, S. M. Piyadin, S. G. Reznikov, Ya. T. Skhomenko,
A. A. Terekhin, A. V. Tishevsky, and T. Uesaka (DSS Collaboration), “Energy dependence of the vector Ay and tensor Ayy and Axx
analyzing powers in deuteron-proton elastic scattering at large scattering angles,” EPJ Web of Conferences 204, 01019 (2019).
O. Mezhenska, A. V. Averyanov, E. V. Chernykh, D. Enache, Yu. V. Gurchin, A. Yu. Isupov, M. Janek, J. -T. Karachuk, A. N. Khrenov,
D. O. Krivenkov, P. K. Kurilkin, V. P. Ladygin, N. B. Ladygina, A. N. Livanov, S. M. Piyadin, S. G. Reznikov, Ya. T. Skhomenko,
A. A. Terekhin, A. V. Tishevsky, T. Uesaka, and J. Urban (DSS Collaboration), “Study of the deuteron analyzing powers in dp elastic
scattering at the energy of 800 MeV”, EPJ Web Conf. 204 (2019) 10001(2019).
N. Paul, A. Obertelli, C. A. Bertulani, A. Corsi, P. Doornenbal, J. L. Rodriguez-Sanchez, G. Authelet, H. Baba, D. Calvet, F. Château,
S. Chen, A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi,
M. Niikura, H. Otsu, C. Péron, A. Peyaud, E. C. Pollacco, J. -Y. Roussé, H. Sakurai, C. Santamaria, M. Sasano, Y. Shiga, D. Steppenbeck, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, T. Ando, T. Arici, A. Blazhev, F. Browne, A. M. Bruce, R. Carroll,
L. X. Chung, M. L. Cortés, M. Dewald, B. Ding, Zs. Dombradi, F. Flavigny, S. Franchoo, F. Giacoppo, M. Górska, A. Gottardo,
K. Hadynska-Klek, Z. Korkulu, S. Koyama, Y. Kubota, A. Jungclaus, J. Lee, M. Lettmann, B. D. Linh, J. Liu, Z. Liu, C. Lizarazo,
C. Louchart, R. Lozeva, K. Matsui, T. Miyazaki, K. Moschner, S. Nagamine, N. Nakatsuka, C. Nita, S. Nishimura, C. R. Nobs,
L. Olivier, S. Ota, Z. Patel, Zs. Podolyák, M. Rudigier, E. Sahin, T. Y. Saito, C. Shand, P. -A. Söderström, I. G. Stefan, T. Sumikama,
D. Suzuki, R. Orlandi, V. Vaquero, Zs. Vajta, V. Werner, K. Wimmer, J. Wu, and Z. Xu, “Prominence of pairing in inclusive (p, 2p) and(p, pn) cross sections from neutron-rich nuclei,” Phys. Rev. Lett. 122, 162503 (2019).
X. Xu, M. Wang, K. Blaum, J. D. Holt, Yu. A. Litvinov, A. Schwenk, J. Simonis, S. R. Stroberg, Y. H. Zhang, H. S. Xu, P. Shuai, X. L. Tu,
X. H. Zhou, F. R. Xu, G. Audi, R. J. Chen, X. C. Chen, C. Y. Fu, Z. Ge, W. J. Huang, S. Litvinov, D. W. Liu, Y. H. Lam, X. W. Ma,
R. S. Mao, A. Ozawa, B. H. Sun, Y. Sun, T. Uesaka, G. Q. Xiao, Y. M. Xing, T. Yamaguchi, Y. Yamaguchi, X. L. Yan, Q. Zeng,
H. W. Zhao, T. C. Zhao, W. Zhang, and W. L. Zhan, “Masses of neutron-rich 52–54 Sc and 54, 56 Ti nuclides: The N = 32 subshell closurein scandium,” Phys. Rev. C 99, 064303 (2019).

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X. Xu, J. H. Liu, C. X. Yuan, Y. M. Xing, M. Wang, Y. H. Zhang, X. H. Zhou, Yu. A. Litvinov, K. Blaum, R. J. Chen, X. C. Chen,
C. Y. Fu, B. S. Gao, J. J. He, S. Kubono, Y. H. Lam, H. F. Li, M. L. Liu, X. W. Ma, P. Shuai, M. Si, M. Z. Sun, X. L. Tu, Q. Wang,
H. S. Xu, X. L. Yan, J. C. Yang, Y. J. Yuan, Q. Zeng, P. Zhang, X. Zhou, W. L. Zhan, S. Litvinov, G. Audi, S. Naimi, T. Uesaka,
Y. Yamaguchi, T. Yamaguchi, A. Ozawa, B. H. Sun, K. Kaneko, Y. Sun, and F. R. Xu, “Masses of ground and isomeric states of 101 In
and configuration-dependent shell evolution in odd-A indium isotopes,” Phys. Rev. C 100, 051303 (2019).
A. Corsi, Y. Kubota, J. Casal, M. Gomez-Ramos, A. M. Moro, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono,
J. Feng, F. Flavigny, J. -M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim,
Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F. M. Marques,
T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, N. A. Orr, S. Ota, H. Otsu, T. Ozaki,
V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. -Y. Rousse, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano,
H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y. L. Sun, M. Tabata, Y. Togano, J. Tsubota, T. Uesaka, Z. H. Yang,
J. Yasuda, K. Yoneda, and J. Zenihiro, “Structure of 13 Be probed via quasi-free scattering,” Phys. Lett. B 797, 134843 (2019).
S. Chen, J. Lee, P. Doornenbal, A. Obertelli, C. Barbieri, Y. Chazono, P. Navrátil, K. Ogata, T. Otsuka, F. Raimondi, V. Som‘a, Y. Utsuno,
K. Yoshida, H. Baba, F. Browne, D. Calvet, F. Château, N. Chiga, A. Corsi, M. L. Cortés, A. Delbart, J. -M. Gheller, A. Giganon,
A. Gillibert, C. Hilaire, T. Isobe, J. Kahlbow, T. Kobayashi, Y. Kubota, V. Lapoux, H. N. Liu, T. Motobayashi, I. Murray, H. Otsu,
V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun, Y. Togano, T. Uesaka, K. Wimmer,
K. Yoneda, N. Achouri, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gašparić, R. -B. Gerst, J. Gibelin, K. I. Hahn,
D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, C. Lehr, B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Y. Park,D. Rossi, E. Sahin, D. Sohler, P. -A. Söderström, S. Takeuchi, H. Törnqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu,
H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti, “Quasifree neutron knockout from 54 Ca corroborates arising N = 34 Neutron
magic number,” Phys. Rev. Lett. 123, 142501 (2019).
V. Ladygin, A. Averyanov, E. Chernykh, D. Enache, Y. Gurchin, A. Isupov, M. Janek, J. -T. Karachuk, A. Khrenov, D. Krivenkov,
P. Kurilkin, N. Ladygina, A. Livanov, O. Mezhenska, S. Piyadin, S. Reznikov, Y. Skhomenko, A. Terekhin, A. Tishevsky, and T. Uesaka,“Spin studies of the short-range correlations with polarized beams at JINR-nuclotron,” JPS Conf. Proc. 26, 023023 (2019).
M. L. Cortés, W. Rodriguez, P. Doornenbal, A. Obertelli, J. D. Holt, S. M. Lenzi, J. Menéndez, F. Nowacki, K. Ogata, A. Poves,
T. R. Rodrı́guez, A. Schwenk, J. Simonis, S. R. Stroberg, K. Yoshida, L. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen,
N. Chiga, A. Corsi, A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux,
H. N. Liu, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun, Y. Togano,
T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gašparić, R. -B. Gerst, J. Gibelin,
K. I. Hahn, D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner,
T. Nakamura, S. Y. Park, D. Rossi, E. Sahin, D. Sohler, P. -A. Söderström, S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang,
V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, L. Zanetti, “Shell evolution of N = 40 isotones towards 60 Ca: First
spectroscopy of 62 Ti,” Phys. Lett. B 800, 135071 (2020).
H. N. Liu, A. Obertelli, P. Doornenbal, C. A. Bertulani, G. Hagen, J. D. Holt, G. R. Jansen, T. D. Morris, A. Schwenk, R. Stroberg,
N. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, M. L. Cortés, A. Delbart, J. -M. Gheller,
A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, T. Motobayashi, I. Murray, H. Otsu, V. Panin,
N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda,
O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gašparić, R. -B. Gerst, J. Gibelin, K. I. Hahn, D. Kim, T. Koiwai,
Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Y. Park, D. Rossi,
E. Sahin, D. Sohler, P. -A. Söderström, S. Takeuchi, H. Törnqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada,
D. Yan, Z. Yang, M. Yasuda, and L. Zanetti, “How robust is the N = 34 subshell closure? first spectroscopy of 52 Ar,” Phys. Rev. Lett.
122, 072502 (2019).
J. Tanaka, C. Bertulani, and S. Typel, “Post-formation in alpha emission from nuclei,” EPJ Web Conf. 227, 01001 (2020).
T. Matsumoto, J. Tanaka, and K. Ogata, “Borromean feshbach resonance in 11 Li studied via 11 Li (p, p′ ),” Prog. Theor. Exp. Phys. 12,
123D02 (2019).
S. Bagchi, R. Kanungo, W. Horiuchi, G. Hagen, T. D. Morris, S. R. Stroberg, T. Suzuki, F. Ameil, J. Atkinson, Y. Ayyad, D. Cortina-Gil,
I. Dillmann, A. Estradé, A. Evdokimov, F. Farinon, H. Geissel, G. Guastalla, R. Janik, S. Kaur, R. Knöbel, J. Kurcewicz, Y. A. Litvinov,
M. Marta, M. Mostazo, I. Mukha, C. Nociforo, H. J. Ong, S. Pietri, A. Prochazka, C. Scheidenberger, B. Sitar, P. Strmen, M. Takechi,
J. Tanaka, Y. Tanaka, I. Tanihata, S. Terashima, J. Vargas, H. Weick, and J. S. Winfield, “Neutron skin and signature of the N = 14 shell
gap found from measured proton radii of 17–22 N,” Phys. Lett. B 790, 251–256 (2019).
S. Bagchi, R. Kanungo, W. Horiuchi, G. Hagen, T. D. Morris, S. R. Stroberg, T. Suzuki, F. Ameil, J. Atkinson, Y. Ayyad, D. Cortina-Gil,
I. Dillmann, A. Estradé, A. Evdokimov, F. Farinon, H. Geissel, G. Guastalla, R. Janik, S. Kaur, R. Knöbel, J. Kurcewicz, Y. Litvinov,
M. Marta, M. Mostazo, I. Mukha, C. Nociforo, H. J. Ong, S. Pietri, A. Prochazka, C. Scheidenberger, B. Sitar, P. Strmen, M. Takechi,
J. Tanaka, Y. Tanaka, I. Tanihata, S. Terashima, J. Vargas, H. Weick, and J. Stuart Winfield, “Measurement of proton-distribution radiiof neutron-rich nitrogen isotopes,” EPJ Web Conf. 223, 01003 (2019).
H. Kouno, Y. Kawashima, K. Tateishi, T. Uesaka, N. Kimizuka, and N. Yanai, “Non-pentacene polarizing agents with improved airstability for triplet dynamic nuclear polarization at room temperature,” J. Phys. Chem. Lett. 10, 2208–2213 (2019).
K. Nishimura, H. Kouno, K. Tateishi, T. Uesaka, K. Ideta, N. Kimizuka, and N. Yanai, “Triplet dynamic nuclear polarization of nanocrystals dispersed in water at room temperature,” Phys. Chem. Chem. Phys. 21, 16408–16412 (2019).
K. Tateishi, M. Negoro, H. Nonaka, A. Kagawa, S. Sando, S. Wada, M. Kitagawa, and T. Uesaka, “Dynamic nuclear polarization withphoto-excited triplet electrons using 6,13-diphenylpentacene,” Phys. Chem. Chem. Phys. 21, 19737–19741 (2019).
H. Kouno, K. Orihashi, K. Nishimura, Y. Kawashima, K. Tateishi, T. Uesaka, N. Kimizuka, and N. Yanai, “Triplet dynamic nuclear
polarization of crystalline ice using water-soluble polarizing agents,” Chem. Commum. 56, 3717–3720 (2020).

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L. Stuhl, M. Sasano, J. Gao, Y. Hirai, K. Yako, T. Wakasa, D. S. Ahn, H. Baba, A. I. Chilug, S. Franchoo, Y. Fujino, N. Fukuda, J. Gibelin,
I. S. Hahn, Z. Halasz, T. Harada, M. N. Harakeh, D. Inomoto, T. Isobe, H. Kasahara, D. Kim, G. G. Kiss, T. Kobayashi, Y. Kondo,
Z. Korkulu, S. Koyama, Y. Kubota, A. Kurihara, H. N. Liu, M. Matsumoto, S. Michimasa, H. Miki, M. Miwa, T. Motobayashi,
T. Nakamura, M. Nishimura, H. Otsu, V. Panin, S. Park, A. T. Saito, H. Sakai, H. Sato, T. Shimada, Y. Shimizu, S. Shimoura,
A. Spiridon, I. C. Stefanescu, X. Sun, Y. L. Sun, H. Suzuki, E. Takada, Y. Togano, T. Tomai, L. Trache, D. Tudor, T. Uesaka, H. Yamada,Z. Yang, M. Yasuda, K. Yoneda, K. Yoshida, J. Zenihiro, and N. Zhang, “Study of spin-isospin responses of radioactive nuclei with thebackground-reduced neutron spectrometer, PANDORA,” Nucl. Instrum. Methods Phys. Res. B 463, 189–194 (2020).
Y. Kubota, M. Sasano, T. Uesaka, M. Dozono, M. Itoh, S. Kawase, M. Kobayashi, C. S. Lee, H. Matsubara, K. Miki, H. Miya, Y. Ono,
S. Ota, K. Sekiguchi, T. Shima, T. Taguchi, T. L. Tang, H. Tokieda, T. Wakasa, T. Wakui, J. Yasuda, and J. Zenihiro, “Development ofa neutron detector with a high position resolution at intermediate energies,” Nucl. Instrum. Methods Phys. Res. A 914, 32–41 (2019).

[Books]H. Sagawa, N. Yoshida, 「量子コンピュータ」, 量子情報理論 第 3 版, 1–300 (2019).

[Proceedings]
T. Yamaguchi, N. Tadano, Y. Abe, M. Amano, Z. Ge, D. Kamioka, T. Moriguchi, D. Nagae, S. Naimi, A. Ozawa, F. Suzaki, S. Suzuki,
T. Suzuki, T. Uesaka, M. Wakasugi, K. Wakayama, and Y. Yamaguchi, “Development of a new in-ring beam monitor in the Rare-RI
Ring,” Nucl. Instrum. Methods Phys. Res. B 463, 241–243 (2019).

Presentations[International conferences/workshops]
H. Sagawa (invited), “Recent progress on single and double spin-isospin excitations,” Neutrino Nuclear Response 2019 (NNR19), RCNP,
Osaka, Japan, May 8–9, 2019.
H. Sagawa (Oral), “Single and double charge exchange excitations of spin-isospin mode,” Nuclear Structure and Dynamics (NSD2019),
Venice, Italy, May 13–17, 2019.
H. Sagawa (invited), “Three-body model for nuclei near and beyond drip line,” Theoretical Nuclear Physics in Padova, Italy, May 20–21,
2019.
S. Naimi (Oral), “First mass measurements with the rare-RI ring at RIBF/RIKEN for nuclear astrophysics,” 27th International Nuclear
Physics Conference 2019, Glasgow, UK, July 29–August 2, 2019.
S. Huang, Z. Yang, and M. Marques (poster), “Experimental study of 4n with 8 He(p, 2p) reaction,” International Nuclear Physics Conference Glasgow, UK, July 29–August 2, 2019.
J. Tanaka (invited), “Clear evidence of α clusters in the ground state of heavy nuclei,” The 27th International Nuclear Physics Conference
Glasgow, UK, July 29–August 2, 2019.
S. Naimi, D. Nagae, Y. Abe, Y. Yamaguchi, S. Omika, K. Inomata, H. Arakawa, S. Hosoi, Y. Inada, W. B. Dou, D. Kajiki, K. Nishimuro,
T. Kobayashi, T. Yamaguchi, D. Hamakawa, M. Mukai, T. Moriguchi, R. Kagesawa, D. Kamioka, A. Ozawa, F. Suzaki, S. Suzuki,
Z. Ge, C. Y. Fu, Q. Wang, M. Wang, S. Ota, S. Michimasa, N. Kitamura, S. Masuoka, D. S. Ahn, H. Suzuki, N. Fukuda, H. Takeda,
Y. Shimizu, Yu. A. Litvinov, G. Lorusso, P. Walker, Zs. Podolyk, M. Wakasugi, and T. Uesaka (Poster), “Mass measurement of neutronrich 122 Rh, 123, 124 Pd and 125 Ag nuclides with rare-RI ring at RIBF in RIKEN,” 28th International Nuclear Physics Conference 2019,
Glasgow, UK, July 29–August 2, 2019.
H. Sagawa (Oral), “Single and double charge exchange excitations of spin-isospin mode,” EPJ Web Conf. 223, 01053 (2019).
H. Sagawa (invited), “EoS from terrestrial experiments: static and dynamic polarizations of nuclear density+B12,” 9th International
Symposium on Nuclear Symmetry Energy (Nusym2019), Da Nang City, Vietnam, September 30–October 4, 2019.
J. Tanaka (invited), “Direct evidence of α clusters in the ground state of heavy nuclei,” The 4th International Workshop on Quasi-Free
Scattering with Radioactive-Ion Beams, October 13–18, 2019.
T. Uesaka, “Possibility of LOREX at RIBF,” LOREX Workshop, GSI, Germany, December12–13, 2019.
H. Sagawa (invited), “Recent topics of single and double phonon spin-isospin excitations,” Vth Topical Workshop on Modern Aspects inNuclear Structure, Bormio, Italy, February 4–9, 2019.
S. En’yo, “A large solid hydrogen target for the proton elastic scattering with high int ensity RI beams,” CLUSHIQ2020, Beppu, Japan,
January 23–24, 2020.

[Domestic conferences/workshops]
立石健一郎, 上坂友洋 (招待講演), 「光励起電子スピンを用いた動的核偏極—超偏極溶液 NMR に向けて」, 第 58 回 NMR 討論会(NMR 討論会・SEST 2019 連合大会), 川崎コンベンションホール, 川崎, 2019 年 11 月 7–9 日.
髙田秀佐, 上坂友洋, 立石健一郎, 吉岡瑞樹, 大竹淑恵, 若林泰生, NOPTREX コラボレーション (口頭発表), 「Triplet-DNP による陽子偏極を利用した中性子スピンフィルターの開発—小型中性子源 RANS での性能評価—」, 日本物理学会 2019 年秋季大会, 山形大学, 山形, 2019 年 9 月 17–20 日.
松村理久 (ポスター発表), 「核分裂生成核種 Sr-90 の陽子および重陽子誘起反応に関する研究」, 日本物理学会第 75 回年次大会, 名
古屋大学, 名古屋, 2020 年 3 月 16–19 日.
上坂友洋 (口頭発表), 「超偏極が拓く科学技術〜フェムト・テクノロジーの未来に向けて〜」, 理研-九大-福岡市-ISIT 連携シンポ
ジウム, 理研和光キャンパス, 和光, 2019 年 5 月 22 日.
上坂友洋 (口頭発表), 「Triplet-DNP enhanced NMR is just around the corner」, DSB プロジェクト年次報告会, 理研横浜キャンパス,鶴見, 2019 年 11 月 13 日.

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原田知也 (口頭発表), 「不安定核 132Sn の逆運動学陽子弾性散乱測定」, 日本物理学会第 75 回年次大会, 名古屋大学, 名古屋, 2020
年 3 月 16–19 日.
延與紫世 (口頭発表), 「大強度 RI ビーム実験のための固体水素標的の開発」, 日本物理学会第 75 回年次大会, 名古屋大学, 名古屋,2020 年 3 月 16–19 日.
土方佑斗 (口頭発表), 「大強度不安定核ビームの粒子識別のための Xe ガス検出器の開発」, 日本物理学会第 75 回年次大会, 名古屋
大学, 名古屋, 2020 年 3 月 16–19 日.

[Seminar]
上坂友洋 (口頭発表), 「核物質の多様性」, 物理学第二教室原子核ハドロン研究室セミナー京都大学, 京都, 2019 年 11 月 29 日.

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Nuclear Science and Transmutation Research Division
Nuclear Spectroscopy Laborarory
1. Abstract

The research group has conducted nuclear-physics studies utilizing stopped/slowed-down radioactive-isotope (RI) beams mainly
at the RIBF facility. These studies are based on the technique of nuclear spectroscopy such as β-ray-detected NMR (β-NMR), γPAD (Perturbed Angular Distribution), laser, and Mössbauer among other methods that takes advantage of intrinsic nuclear properties
such as nuclear spins, electromagnetic moments, and decay modes. In particular, techniques and devices for the production of spincontrolled RI beams have been developed and combined to the spectroscopic studies, which enable high-sensitivity measurements ofspin precessions/resonances through a change in the angular distribution of radiations. Anomalous nuclear structures and propertiesof far unstable nuclei are investigated from thus determined spin-related observables. The group also aims to apply such techniques tointerdisciplinary fields such as fundamental physics and materials science by exploiting nuclear probes.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Nuclear spectroscopy utilizing spin-oriented fast RI beams
Nuclear/Atomic laser spectroscopy & SLOWRI R&DApplication of RI probes to materials science
Fundamental physics: Study of symmetry

3. Summary of Research Activity(1) Nuclear spectroscopy utilizing spin-oriented fast RI beams
Measurements of static electromagnetic nuclear moments over a substantial region of the nuclear chart have been conducted forstructure studies on the nuclei far from the β-decay stability. Utilizing nuclear spin orientation phenomena of RIs created in the
projectile-fragmentation reaction, ground- and excited-state electromagnetic nuclear moments been determined by means of the βray-detected nuclear magnetic resonance (β-NMR) and the γ-ray time diﬀerential perturbed angular distribution (γ-TDPAD) methods.
In particular, a new method developed for controlling spin in a system of rare RIs, taking advantage of the mechanism of the two-step
projectile fragmentation reaction combined with the momentum-dispersion matching technique, has been developed and employedmaking fully use of world’s highest intensity rare RIBs delivered from BigRIPS for rare isotopes.
(2) Nuclear/Atomic laser spectroscopy & SLOWRI R&D
The group has been conducting system development for nuclear laser spectroscopy from the following two approaches in orderto realize experiments for rare isotopes at RIBF. One is collinear laser spectroscopy for a large variety of elements using sloweddown RI beams produced via a projectile-fragmentation reaction, which can be achieved only by the universal low-energy RI-beamdelivery system, SLOWRI, under installation in collaboration with the SLOWRI Team. This slowed-down RI-beam scheme enables
to perform high-precision laser spectroscopy even with fast-fragmentation-based RIBs without the elemental limitation problematicin the ISOL-based RIBs.
The other approach is a new method utilizing superfluid helium (He II) as a stopping medium of energetic RI beams, in which thecharacteristic atomic properties of ions surrounded by superfluid helium enables us to perform unique nuclear laser spectroscopy. RIions trapped in He II are known to exhibit a characteristic excitation spectrum significantly blue-shifted compared with the emission
one. Consequently, the background derived from the excitation-laser stray light, which often causes serious problems in measurements,
can be drastically reduced.
(3) Application of RI probes to materials science
The application of RI and heavy ion beams as a probe for condensed matter studies is also conducted by the group. The microscopic material dynamics and properties have been investigated through the deduced internal local fields and the spin relaxation of
RI probes based on various spectroscopies utilizing RI probes such as β-NMR/NQR spectroscopy, Mössbauer spectroscopy, the γ-ray
time diﬀerential perturbed angular correlation (γ-TDPAC) spectroscopy. Furthermore, studies on the control of electrical conductivityof diamond by boron and nitrogen implantation are ongoing.
Provided that highly spin-polarized RI probes are produced independently of their element properties and doped into a substanceas an impurity, the constituent particle of the substance can be substituted by the same element RI probe without changing the material
structure. This scheme provides a new opportunity for materials-science researches, but a key technology, production of elementindependent highly spin-polarized RI beams, has not yet been achieved. In this subject, the group has conducted R&D studies torealize an ultra-slow & highly-spin-polarized RI beams, based on the technique of the atomic beam resonance.
(4) Fundamental physics: Study of symmetry
The nuclear spins of stable and unstable isotopes sometimes play important roles in fundamental physics research. New experimental methods and devices have been developed for studies of the violation of time reversal symmetry (T-violation) using spinpolarized nuclei. These experiments aim to detect the small frequency shift in the spin precession arising from new mechanisms
beyond the Standard Model.

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Members
Director
Hideki UENO
Research/Technical Scientists
Hiroki YAMAZAKI (Senior Research Scientist)
Yuichi ICHIKAWA (Senior Research Scientist)

Aiko TAKAMINE (Research Scientist)

Research & Development Scientist
Tetsu SONODA
Special Postdoctoral Researcher
Hiroki NISHIBATA
Postdoctoral Researcher
Minori TAJIMA
Research Associate
Aleksey GLADKOV
Junior Research Associate
Keita KAWATA (Univ. of Tokyo)
Senior Visiting Scientists
Yukari MATSUO (Hosei Univ.)
Hideyuki SAKAI (Univ. of Tokyo)

Takaharu OTSUKA (Univ. of Tokyo)

Visiting Scientists
Dimiter Loukanov BALABANSKI (IHIN)
Georgi GEORGIEV (CNRS-IN2P3)
Kei IMAMURA (Okayama Univ.)
Yoko ISHIBASHI (Tohoku Univ.)
Yoshio KOBAYASHI (Univ. of Electro-Commun.)
Kenya KUBO (Int’l Christian Univ.)
Kensaku MATSUTA (Osaka Univ.)
Jun MIYAZAKI (Hokuriku Univ.)
Takamasa MOMOSE (The Univ. of British Columbia)
Jiro MURATA (Rikkyo Univ.)

Jin NAKAMURA (Univ. of Electro-Commun.)
Hiroki NISHIBATA (Kyushu Univ.)
Naoki NISHIDA (Tokyo Univ. Sci)
Tomoya SATO (Tokyo Tech)
Wataru SATO (Kanazawa Univ.)
Andrew E. STUCHBERY (The Australian Nat’l Univ.)
Satoshi TSUTSUI (Japan Synchrotron Radiation Res. Inst.)
Yasuhiro YAMADA (Tokyo Univ. Sci)
Deyan T. YORDANOV (Inst. de Phys.Nucl. d’Orsay)
Akihiro YOSHIMI (Okayama Univ.)

Student Trainees
Shota AMAGASA (Tokyo Univ. Sci)
Takumi ASAKAWA (Hosei Univ.)
Kazuho DOI (Hosei Univ.)
Miru DOI (Hosei Univ.)
Takumi FUNABASHI (Tokyo Univ. Sci)
Timothy J. GRAY (The Australian Nat’l Univ.)
Kentaro HAMANO (Univ. of Electro-Commun.)
Kazuki HAMAZAKI (Tokyo Univ. Sci)
Kyouichi IZUOKA (Tokyo Univ. Sci)
Masato KIJI (Univ. of Electro-Commun.)Naoki KOSHIKAWA (Tokyo Univ. Sci)

Masaki NISHIMURA (Hosei Univ.)
Shinichi OKAMURA (Univ. of Ferrara)David PELLETIER (ENSICAEN)
Yusuke SASAKI (Hosei Univ.)
Ryo TAKEMURA (Tokyo Univ. Sci)
Yuika TAKEUCHI (Hosei Univ.)
Kenta TSUBURA (Hosei Univ.)
Tomoaki YADA (Hosei Univ.)
Takumi YAMAMOTO (Hosei Univ.)
Fumiya YOKOSUKA (Aoyama Gakuin Univ.)

Interns
Chengyu GUO (Peking Univ.)
Chan HEO (The Univ. of Hong Kong)
Meng Chit HO (The Univ. of Hong Kong)
Ziyao HU (Peking Univ.)
Min Young KIM (Seoul Nat’l Univ.)
Minju KUM (Seoul Nat’l Univ.)
Euijoon KWON (Seoul Nat’l Univ.)
Joo Hyun LEE (Seoul Nat’l Univ.)
Pak Yi LI (The Univ. of Hong Kong)

Fumiya OURA (Tohoku Univ.)
Shoko TAKESHIGE (Rikkyo Univ.)
Masashi TAWARA (Rikkyo Univ.)
Hao WANG (Peking Univ.)
Sau Hei WONG (The Univ. of Hong Kong)
Seungbum WOO (Seoul Nat’l Univ.)
Lisheng YANG (Peking Univ.)
Ryan W. YEUNG (The Univ. of Hong Kong)
Zhenxiang ZHOU (Peking Univ.)

Temporary Staﬃng- 265 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Emiko FUJINO

Naoko YUASA

AssistantIzumi YOSHIDA

List of Publications & Presentations
Publications[Original papers]
M. Tajima, N. Kuroda, C. Amsler, H. Breuker, C. Evans, M. Fleck, A. Gligorova, H. Higaki, Y. Kanai, B. Kolbinger, A. Lanz, M. Leali,
V. Mäckel, C. Malbrunot, V. Mascagna, Y. Matsuda, D. Murtagh, Y. Nagata, A. Nanda, B. Radics, M. Simon, S. Ulmer, L. Venturelli,
E. Widmann, M. Wiesingerc, and Y. Yamazaki, “Antiproton beams with low energy spread for antihydrogen production,” J. Instrum.
14, P05009 (2019).
L. C. Tao, Y. Ichikawa, C. X. Yuan, Y. Ishibashi, A. Takamine, A. Gladkov, T. Fujita, K. Asahi, T. Egami, C. Funayama, K. Imamura,
J. L. Lou, T. Kawaguchi, S. Kojima, T. Nishizaka, T. Sato, D. Tominaga, X. F. Yang, H. Yamazaki, Y. L. Ye, H. Ueno, Y. Yanagisawa,
and K. Yoshida, “Negative parity states in 39 Cl configured by crossing major shell orbits,” Chin. Phys. Lett. 36, 062101-1–4 (2019).
D. S. Ahn, N. Fukuda, H. Geissel, N. Inabe, N. Iwasa, T. Kubo, K. Kusaka, D. J. Morrissey, D. Murai, T. Nakamura, M. Ohtake, H. Otsu,
H. Sato, B. M. Sherrill, Y. Shimizu, H. Suzuki, H. Takeda, O. B. Tarasov, H. Ueno, Y. Yanagisawa, and K. Yoshida, “Location of theneutron dripline at fluorine and neon,” Phys. Rev. Lett. 123, 212501-1–6 (2019). [Featured in Physics] [Editors’ Suggestion]
S. Tsutsui, M. Mizumaki, and Y. Kobayashi, “Electronic and atomic dynamics in Sm and Eu cage-structured intermetallics,” Hyperfine
Interact. 240, 84-1–16 (2019).
T. Funabashi, Y. Kobayashi, and Y. Yamada, “Metastable iron carbide thin films produced by pulsed laser deposition of iron in methane
atmosphere,” Hyperfine Interact. 240, 121-1–8 (2019).
F. Boulay, G. S. Simpson, Y. Ichikawa, S. Kisyov, D. Bucurescu, A. Takamine, D. S. Ahn, K. Asahi, H. Baba, D. L. Balabanski,
T. Egami, T. Fujita, N. Fukuda, C. Funayama, T. Furukawa, G. Georgiev, A. Gladkov, M. Hass, K. Imamura, N. Inabe, Y. Ishibashi,
T. Kawaguchi, T. Kawamura, W. Kim, Y. Kobayashi, S. Kojima, A. Kusoglu, R. Lozeva, S. Momiyama, I. Mukul, M. Niikura, H. Nishibata, T. Nishizaka, A. Odahara, Y. Ohtomo, D. Ralet, T. Sato, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda, L. C. Tao, Y. Togano,
D. Tominaga, H. Ueno, H. Yamazaki, X. F. Yang, and J. M. Daugas, “g-Factor of the 99 Zr (7/2+ ) isomer: Monopole evolution in shapecoexisting region,” Phys. Rev. Lett. 124, 112501-1–6 (2020).
K. Hamazaki, Y. Kobayashi, and Y. Yamada, “Iron nitride films produced by arc deposition of iron in a nitrogen atmosphere,” Hyperfine
Interact. 241, 4-1–10 (2020).
Y. Yamada, Y. Sato, Y. Kobayashi, T. Ando, N. Takahama, K. Some, M. Sato, M. Mihara, M. K. Kubo, W. Sato, J. Miyazaki, T. Nagatomo,
J. Kobayashi, A. Okazawa, S. Sato, and A. Kitagawa, “In-beam Mössbauer spectra for 57 Mn implanted sulfur hexafluoride,” Hyperfine
Interact. 241, 15-1–15 (2020).
T. Otsuka, Y. Tsunoda, T. Abe, N. Shimizu, and P. Van Duppen, “Underlying structure of collective bands and self-organization in quantum
systems,” Phys. Rev. Lett. 123, 222502 (2019).
S. Sels, T. Day Goodacre, B. A. Marsh, A. Pastore, W. Ryssens, Y. Tsunoda, N. Althubiti, B. Andel, A. N. Andreyev, D. Atanasov,
A. E. Barzakh, M. Bender, J. Billowes, K. Blaum, T. E. Cocolios, J. G. Cubiss, J. Dobaczewski, G. J. Farooq-Smith, D. V. Fedorov,
V. N. Fedosseev, K. T. Flanagan, L. P. Gaﬀney, L. Ghys, P.-H. Heenen, M. Huyse, S. Kreim, D. Lunney, K. M. Lynch, V. Manea,
Y. Martinez Palenzuela, T. M. Medonca, P. L. Molkanov, T. Otsuka, J. P. Ramos, R. E. Rossel, S. Rothe, L. Schweikhard, M. D. Seliverstov, P. Spagnoletti, C. Van Beveren, P. Van Duppen, M. Veinhard, E. Verstraelen, A. Welker, K. Wendt, F. Wienholtz, R. N. Wolf, andA. Zadvornaya, “Shape staggering of mid-shell mercury isotopes from in-source laser spectroscopy compared with density functional
theory and Monte Carlo shell model calculations,” Phys. Rev. C 99, 044306 (2019).
F. Flavigny, J. Elseviers, A. N. Andreyev, C. Bauer, V. Bildstein, A. Blazhev, B. A. Brown, H. De Witte, J. Diriken, V. N. Fedosseev,
S. Franchoo, R. Gernhäuser, M. Huyse, S. Ilieva, S. Klupp, Th. Kröll, R. Lutter, B. A. Marsh, D. Mücher, K. Nowak, T. Otsuka,
J. Pakarinen, N. Patronis, R. Raabe, F. Recchia, P. Reiter, T. Roger, S. Sambi, M. Seidlitz, M. D. Seliverstov, B. Siebeck, Y. Tsunoda,
P. Van Duppen, M. Vermeulen, M. Von Schmid, D. Voulot, N. Warr, F. Wenander, and K. Wimmer, “Microscopic structure of coexisting0+ states in 68 Ni probed via two-neutron transfer,” Phys. Rev. C 99, 054332 (2019).
L. Xie, X. F. Yang, C. Wraith, C. Babcock, J. Bieroń, J. Billowes, M. L. Bissell, K. Blaum, B. Cheal, L. Filippin, K. T. Flanagan,
R. F. Garcia Ruiz, W. Gins, G. Gaigalas, M. Godefroid, C. Gorges, L. K. Grob, H. Heylen, P. Jönsson, S. Kaufmann, M. Kowalska,
J. Krämer, S. Malbrunot-Ettenauer, R. Neugart, G. Neyens, W. Nörtershäuser, T. Otsuka, J. Papuga, R. Sánchez, Y. Tsunoda, and
D. T. Yordanov, “Nuclear charge radii of 62–80 Zn and their dependence on cross-shell proton excitations,” Phys. Lett. B 797, 134805(2019).
C. Hornung, D. Amanbayev, I. Dedes, G. Kripko-Koncz, I. Miskun, N. Shimizu, S. Ayet San Andrés, J. Bergmann, T. Dickel, J. Dudek,
J. Ebert, H. Geissel, M. Górska, H. Grawe, F. Greiner, E. Haettner, T. Otsuka, W. R. Plaß, S. Purushothaman, A.-K. Rink, C. Scheidenberger, H. Weick, S. Bagchi, A. Blazhev, O. Charviakova, D. Curien, A. Finlay, S. Kaur, W. Lippert, J.-H. Otto, Z. Patyk, S. Pietri,
Y. K. Tanaka, Y. Tsunoda, and J. S. Winfield, “Isomer studies in the vicinity of the doubly-magic nucleus 100 Sn: Observation of a new
low-lying isomeric state in 97 Ag,” Phys. Lett. B 802, 135200 (2019).
T. Otsuka, A. Gade, O. Sorlin, T. Suzuki, and Y. Utsuno, “Evolution of shell structure in exotic nuclei,” Rev. Mod. Phys. 92, 015002(2020).
T. Miyagi, T. Abe, M. Kohno, P. Navratil, R. Okamoto, T. Otsuka, N. Shimizu, and S. R. Stroberg, “Ground-state properties of doubly
magic nuclei from the unitary-model-operator approach with the chiral two- and three-nucleon forces,” Phys. Rev. C 100, 034310- 266 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53(2019).
B. Abromeit, V. Tripathi, H. L. Crawford, S. N. Liddick, Y. Utsuno, P. C. Bender, B. P. Crider, R. Dungan, P. Fallon, K. Kravvaris,
N. Larson, R. S. Lubna, A. O. Macchiavelli, T. Otsuka, C. J. Prokop, A. L. Richard, N. Shimizu, S. L. Tabor, A. Volya, and S. Yoshida,“Beta decay of T z = +11/2 isotopes 37 Al and 39 Si understanding Gamow Teller strength distribution in neutron rich nuclei,” Phys. Rev.
C 100, 014323 (2019).
A. Matta, W. N. Catford, N. A. Orr, J. Henderson, P. Ruotsalainen, G. Hackman, A. B. Garnsworthy, F. Delaunay, R. Wilkinson, G. Lotay,
N. Tsunoda, T. Otsuka, A. J. Knapton, G. C. Ball, N. Bernier, C. Burbadge, A. Chester, D. S. Cross, S. Cruz, C. Aa. Diget, T. Domingo,
T. E. Drake, L. J. Evitts, F. H. Garcia, S. Hallam, E. MacConnachie, M. Moukaddam, D. Muecher, E. Padilla-Rodal, O. Paetkau,
J. Park, J. L. Pore, U. Rizwan, J. Smallcombe, J. K. Smith, K. Starosta, C. E. Svensson, J. Williams, and M. Williams, “Shell evolution
approaching the N = 20 island of inversion: Structure of 29 Mg,” Phys. Rev. C 99, 044320 (2019).
Y. L. Sun, A. Obertelli, P. Doornenbal, C. Barbieri, Y. Chazono, T. Duguet, H. N. Liu, P. Navrátil, F. Nowacki, K. Ogata, T. Otsuka,
F. Raimondi, V. Somà, Y. Utsuno, K. Yoshida, N. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi,
M. L. Cortés, A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. Togano, T. Uesaka,
K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gas̆parić, R. -B. Gerst, J. Gibelin, K. I. Hahn,
D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura,
S. Y. Park, D. Rossi, E. Sahin, D. Sohler, P. -A. Söderström, S. Takeuchi, H. Törnqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner,
X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti, “Restoration of the natural E(1/2+1 ) − E(3/2+1 ) energy splitting in odd-k
isotopes towards N = 40,” Phys. Lett. B 802, 135215 (2020).
S. Chen, J. Lee, P. Doornenbal, A. Obertelli, C. Barbieri, Y. Chazono, P. Navrátil, K. Ogata, T. Otsuka, F. Raimondi, V. Somà, Y. Utsuno,
K. Yoshida, H. Baba, F. Browne, D. Calvet, F. Château, N. Chiga, A. Corsi, M. L. Cortés, A. Delbart, J.-M. Gheller, A. Giganon,
A. Gillibert, C. Hilaire, T. Isobe, J. Kahlbow, T. Kobayashi, Y. Kubota, V. Lapoux, H. N. Liu, T. Motobayashi, I. Murray, H. Otsu,
V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun, Y. Togano, T. Uesaka, K. Wimmer,
K. Yoneda, N. Achouri, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gas̆parić, R.-B. Gerst, J. Gibelin, K. I. Hahn,
D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, C. Lehr, B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Y. Park,D. Rossi, E. Sahin, D. Sohler, P.-A. Söderström, S. Takeuchi, H. Törnqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu,
H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti, “Quasifree neutron knockout from corroborates arising neutron magic
number,” Phys. Rev. Lett. 123, 142501 (2020).
F. Diel, Y. Fujita, H. Fujita, F. Cappuzzello, E. Ganioğlu, E.-W. Grewe, T. Hashimoto, K. Hatanaka, M. Honma, T. Itoh, J. Jolie,
B. Liu, T. Otsuka, K. Takahisa, G. Susoy, B. Rubio, and A. Tamii, “High-resolution study of the Gamow-Teller (GT-) strength in
the 60 Zn(3 He, t)64 Ge reaction,” Phys. Rev. C 99, 054322 (2019).

[Review article]
Y. Ichikawa, “Nuclear shell evolution with shape deformation—Structure of exotic nuclei investigated by the magnetic moment—ʢʮม‫ܗ‬͠ͳ͕Β֪ਐԽ—࣓‫ؾ‬ϞʔϝϯτͰ୳ΔΤΩκνοΫ֩ͷʰத਎ʱʯʣ,” Isotope News 765, 26–29 (2019).

Presentations[International conferences/workshops]
H. Ueno (invited), “Nuclear-physics research based on RI spin orientation technique,” XXXVI Mazurian Lakes Conference on Physics,
Piaski, Poland, September 1–7, 2019.
A. Takamine (invited), “Recent progress in the development of gas cells, SHE results combining GARIS with GASCELL+MRTOF,”
Expert Meeting on Next-Generation Fragment Separators 2019, Darmstadt, Germany, September 30–October 3, 2019.
Y. Ichikawa (invited), “Magnetic-moment measurement of exotic nuclei using spin-oriented RI beams at RIBF,” 14th Asia-Pacific Physics
Conference (APPC 2019), Sarawak, Malaysia, November 17–22, 2019.
T. Otsuka (invited), “Self-organization of quantum systems and the structure of heavy nuclei,” Workshop Physics between lead anduranium: In preparation of new experimental campaigns at ISOLDE, Leuven, Bergium, April 16–18, 2019.
T. Otsuka (invited), “Alpha clustering in nuclei and the shell model,” Theoretical Nuclear Physics in Padova: A Meeting in Honor ofProf. Andrea Vitturi, Padova, Italy, May 20–21 2019.
T. Otsuka (invited), “Self-organization in nuclear structure and its impact to heavy nuclei—A challenge to Bohr-Mottelson’s picture and afuture prospect—,” LXIX International Conference on Nuclear Spectroscopy and Nuclear Structure “Fundamental Problems of Nuclear
Physics, Nuclei at Borders of Nucleon Stability, High Technologies,” (Nucleus-2019) , Dubna, Russia, July 1–5, 2019.
T. Otsuka (invited), “Nuclear matrix elements with advanced shell model methods,” Workshop on Progress and Challenges in Neutrinoless
Double Beta Decay, Trento, Italy, July 15–19, 2019.
T. Otsuka (invited), “Ab initio studies on the dripiline of the Island-of-Inversion nuclei,” Workshop on Ab initio Nuclear Theory fromBreakthroughs to Applications, Guildford, UK, July 24–26, 2019.
T. Otsuka (oral), “Self-organization in atomic nuclei and nuclear collectivity,” 27th International Nuclear Physics Conference (INPC2019), Glasgow, UK, July 29–August 2, 2019.
T. Otsuka (invited), “Precision nuclear structure via the Monte-Carlo shell model,” ESNT Workshop Laser Spectroscopy as a Tool for
Nuclear Theories, Saclay, France, October 7–11, 2019.
T. Otsuka (invited), “Evolution of shape and shell of atomic nuclei and the self-organization,” 2XVII International Meeting on “Selected
topics in nuclear and atomic physics,” Fiera di Primiero, Italy, September 30–October 4, 2019.
T. Otsuka (invited), “Olaf gets into shapes,” Symposium on “Particles, photons, and fields: Messengers of violent events from the nucleus,- 267 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

through the sky, to the cosmos,” Groningen, the Netherlands, November 21, 2019.
T. Otsuka (invited), “Self-organization of quantum systems and nuclear collectivity,” International Symposium on Clustering as a Window
on the Hierarchical Structure of Quantum Systems (CLUSHIQ2020), Beppu, Japan, January 23–24, 2020.
T. Otsuka (invited), “Self-organization in nuclear collective bands,” Fifth Topical Workshops on Modern Aspects of Nuclear Structure,
Bormio, Italy, February 4–9, 2020.
T. Otsuka (invited), “Nuclear matrix elements of neutrinoless double beta decay calculated by Monte Carlo shell model for 76 Ge and136
Xe,” International Conference on Neutrino and Nuclear Physics 2020 (CNNP2020), Cape Town, South Africa, February 24–28,
2020.
T. Otsuka (invited), “Structure of F-Ne-Na-Mg isotopes and new mechanism of driplines,” Workshop on Progress in Ab Initio Techniquesin Nuclear Physics, Vancouver, Canada, March 3–6, 2020.

[Domestic conferences/workshops]ࢢ઒༤Ұ, ʮ‫ىྭ֩ࢠݪ‬ঢ়ଶͷ࣓‫ؾ‬Ϟʔϝϯτଌఆʯ, 2019 ೥౓ʮ෺࣭֊૚‫ݪ‬ཧ‫ڀݚ‬ʯˍʮϔςϩք໘‫ڀݚ‬ʯ߹ಉय़߹॓, ‫఼ޚ‬৔,2019 ೥ 5 ݄ 10–11 ೔.
্໺लथ, “Highly Spin-polarized RI beams and the application to nuclear and condensed-matter physics ,” ৽ֶज़ྖҬʮӉ஦‫؍‬ଌ‫ݕ‬ग़‫ࢠྔͱث‬ϏʔϜͷग़ձ͍ɻ ৽ͨͳԠ༻΁ͷՍ͚‫ڮ‬ɻʯୈ 1 ճྖҬશମձٞ, ౦‫ژ‬େֶ Kavli IPMU, ദࢢ, 2019 ೥ 7 ݄ 15–16 ೔.
ߴๆѪࢠ, “Development of an RF ion guide gas cell for universal ultra slow RI beams,” ৽ֶज़ྖҬʮӉ஦‫؍‬ଌ‫ݕ‬ग़‫ࢠྔͱث‬ϏʔϜͷग़ձ͍ɻ৽ͨͳԠ༻΁ͷՍ͚‫ڮ‬ɻʯ, ୈ 1 ճྖҬશମձٞ, ౦‫ژ‬େֶ Kavli IPMU, ദ, 2019 ೥ 7 ݄ 15–16 ೔.
ࠓҪ߁‫و‬, ౻ࢬ྄, ২஛ஐ, ࡫ඌొ, ٢ଜଠ඙, ٢ଜߒ࢘, ٢‫ݟ‬জ༸, ‫ٶ‬ຊ༞थ, ૿ా޹඙, ‫ݪ‬ल໌, ࠓଜ‫ܛ‬, ্֞֎मҰ, த઒޹ल, ۚҪอ೭, ࢢ઒༤Ұ, ௕༑ܼ, ຊా༸հ, ࡔ্࿨೭, ʮྔࢠΠΦϯϏʔϜʢQIB) ෼ޫʹ޲͚ͨ Yb υʔϓϑΝΠόʔΛ༻͍ͨ 987 nm ޫͷ૿෯ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ‫ذ‬ෞେֶ༄‫ށ‬Ωϟϯύε, ‫ذ‬ෞ, 2019 ೥ 9 ݄ 10–13 ೔.
ࠓҪ৳໌, ಊԂণഢ, ಓਖ਼৽Ұ࿠, ୸‫ה‬૱೭, େా৾ี, J. W. Hwang, ‫ؠ‬ຊͪͻΖ, ઒੉ᰌҰ࿠, ઒ా‫ܟ‬ଠ, ๺ଜಙོ, ૿ԬᠳҰ࿕, த໺‫ܟ‬ଠ, P. Schrock, ླ໦େհ, ֯ాཧ‫ࢠܙ‬, K. Wimmer, for ImPACT17-02-02 collaboration, ʮ‫ٯ‬ӡಈֶ 79 Se(d, p) ൓ԠʹΑΔதੑࢠ
ั֫൓Ԡஅ໘ੵͷධՁʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶখന઒Ωϟϯύε, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
઒ా‫ܟ‬ଠ, େా৾ี, ಊԂণഢ, મኍेࡾ, ‫ؠ‬ຊͪͻΖ, ๺ଜಙོ, ञҪӳߦ, ࡫໺‫لڡ‬, ૿ԬᠳҰ࿕, ಓਖ਼৽Ұ࿠, ԣࢁྠ, ໼޲‫ݠ‬ଠ࿠,
Laszlo STUHL, ࡔ‫ོ࣏ޱ‬, ‫ాݪ‬஌໵, ࣉౢ஌, ੢ാᔨ‫ر‬, ֯ాཧ‫ࢠܙ‬, ࠓҪ৳໌, Ningtao Zhang, Jongwon Hwang, ԕ౻ོ࢙, ʮೖࣹ֩ഁࡅ൓ԠʹΑΔ 52 Fe पล֩ͷߴεϐϯΞΠιϚʔͷੜ੒ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶখന઒Ωϟϯύε, ࢁ‫ܗ‬,2019 ೥ 9 ݄ 17–20 ೔.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑ଠ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. Moon, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ߴๆѪࢠ, ৿ాߒհ, H. Wollnik, ʮMRTOF-MS Λ༻͍ͨ 207 Ra ͷਫ਼ີ࣭ྔ—่յಛੑଌ
ఆʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶখന઒Ωϟϯύε, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
Ӊ౎໺য়, ࢢ઒ོහ, ਗ਼ਫଇ޹, େ௩޹࣏, ʮ42 Ca ʹ͓͚Δඇ࣠ରশ௒ม‫ܗ‬ঢ়ଶͱଟॏม‫ڞܗ‬ଘʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶখന઒Ωϟϯύε, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
֯ా༎հ, େ௩޹࣏, ਗ਼ਫଇ޹, ʮϞϯςΧϧϩ֪໛‫ʹܕ‬ΑΔ Sm ಉҐମͷ‫ܗ‬ঢ়มԽͷ‫ڀݚ‬ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶখന઒Ωϟϯύε, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
Ѩ෦‫ڤ‬, P. Maris, େ௩޹࣏, ਗ਼ਫଇ޹, ֯ా༎հ, Ӊ౎໺য়, J. P. Vary, ٢ా‫ږ‬, ʮϞϯςΧϧϩ֪໛‫ʹܕ‬ΑΔୈҰ‫ݪ‬ཧ‫͔ࢉܭ‬ΒͷΞϧϑΝΫϥελʔߏ଄ͷ‫ڀݚ‬ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶখന઒Ωϟϯύε, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
্໺लथ, ʮ֩੔ྻ RI ϏʔϜΛ༻͍ͨ β-NMR ଌఆ๏ʯ, ৽ֶज़ྖҬʮΫϥελʔ֊૚ʯ&ʮྔࢠϏʔϜԠ༻ʯ߹ಉ‫ݕ‬ग़‫ث‬ϫʔΫγϣοϓ, ౦๺େֶ੨༿ࢁΩϟϯύε, ઋ୆, 2019 ೥ 9 ݄ 20–21 ೔.
େ௩޹࣏ʢট଴ߨԋʣ, ʮ‫֩ࢠݪ‬෺ཧͷύϥμΠϜγϑτͱ‫ژ‬ίϯϐϡʔλʯ, ‫ڀݚ‬ձ γϛϡϨʔγϣϯʹΑΔӉ஦ͷ‫ج‬ຊ๏ଇͱਐ
Խͷղ໌ʹ޲͚ͯ , ‫౎ژ‬, 2019 ೥ 12 ݄ 16–19 ೔.
খᖒ௚໵, ௕ᖛ߂‫ق‬, ૣਫ༑༸, தଜ‫ܓ‬༎, খߴ߁র, ాத߳௡ੜ, େ௩ະདྷ, খ৿༗‫ࢠر‬, ࢢ઒༤Ұ, Ӌ৔޺ޫ, ্໺लथ, ञ‫ݟ‬ହ‫׮‬,ʮϑϥϯγ΢Ϝ‫ࢠݪ‬ͷి‫ؾ‬૒‫ࢠۃ‬ೳ཰୳ࡧͷͨΊͷද໘ి཭ΠΦϯ‫ݯ‬ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰ʢ໊‫ݹ‬԰େֶ‫ݱ‬஍։࠵தࢭʣ, 2020 ೥ 3 ݄ 16–19 ೔.
ԣਢլจ࠸, ߴๆѪࢠ, ాౡඒయ, Ԭ໺ହල, ࠤʑ໦༔ี, ઙՏ୓ޫ, ൧ଜल‫ل‬, ࿨ాಓ࣏, H. A. Schuessler, দඌ༝լར, ্໺लथ, લా͸Δ͔, ʮίϦχΞϨʔβʔ෼ޫΛ࢖ͬͨ Zr ಉҐମͷ֩ߏ଄‫͚ͨ޲ʹڀݚ‬Ϩʔβʔޫ‫ݯ‬։ൃʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ,໊‫ݹ‬԰ʢ໊‫ݹ‬԰େֶ‫ݱ‬஍։࠵தࢭʣ, 2020 ೥ 3 ݄ 16–19 ೔.
੢ଜণً, ࠓଜ‫ܛ‬, ߴๆѪࢠ, ཐྑ݈ଠ, Aleksey Gladkov, ஛಺༝ҥՖ, ౔‫ྤࡾډ‬, ࢁຊঊ, ాౡඒయ, ઙՏ୓ޫ, ࠤʑ໦༔ี, ౔ҪҰา,઒ా‫ܟ‬ଠ, ੢ാᔨ‫ر‬, ࢢ઒༤Ұ, ্໺लथ, দඌ༝լར, ʮӷମ஠ૉ‫ڥ؀‬Լʹ͓͚Δߴ଎ Rb ΠΦϯϏʔϜͷఀࢭҐஔ੍‫ޚ‬ʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰ʢ໊‫ݹ‬԰େֶ‫ݱ‬஍։࠵தࢭʣ, 2020 ೥ 3 ݄ 16–19 ೔.
ཐྑ݈ଠ, ࠓଜ‫ܛ‬, ߴๆѪࢠ, ੢ଜণً, Aleksey Gladkov, ஛಺༝ҥՖ, ౔‫ྤࡾډ‬, ࢁຊঊ, ాౡඒయ, ઙՏ୓ޫ, ࠤʑ໦༔ี, ౔ҪҰา,઒ా‫ܟ‬ଠ, ੢ാᔨ‫ر‬, ࢢ઒༤Ұ, ্໺लथ, দඌ༝լར, ʮ֩Ϟʔϝϯτଌఆ๏։ൃͷͨΊͷޫֶ༻ΫϥΠΦελοτʹ͓͚Δ Rb
ͷऩྔଌఆʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰ʢ໊‫ݹ‬԰େֶ‫ݱ‬஍։࠵தࢭʣ, 2020 ೥ 3 ݄ 16–19 ೔.

Press releases“Zirconium isotopes are suddenly deformed even in the excited stateʢʮδϧίχ΢ϜಉҐମ͸ྭ‫ى‬ঢ়ଶͰ΋ಥવม‫͢ܗ‬Δʯʣ,” press
release from RIKEN, March 17, 2020.
RIKEN HP: https://www.riken.jp/press/2020/20200317_2/index.html .
“Basic principles of nuclear shape and self-organization in quantum systems ʢʮ‫֩ࢠݪ‬ͷ‫ܗ‬ͷ‫ج‬ຊ‫ݪ‬ཧͱྔࢠ‫Ͱܥ‬ͷࣗ‫ݾ‬૊৫Խʯʣ,”joint press-release from the University of Tokyo and RIKEN, November 26, 2019.
The Univ. of Tokyo HP: https://www.s.u-tokyo.ac.jp/ja/press/2019/6629/ .
RIKEN HP: https://www.riken.jp/press/2019/20191126_1/index.html .

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53“Research group lead by RIKEN and the University of Tokyo succeeded in measuring excited-state nuclear magnetic moment of a neutronrich copper isotope ʢʮཧ‫ͱݚ‬౦େͳͲ, தੑࢠա৒ͳಔಉҐମ‫֩ࢠݪ‬ͷྭ‫ى‬ঢ়ଶͷ࣓‫ؾ‬Ϟʔϝϯτଌఆʹ੒ޭʯʣ,” Nikkei Shinbun
Newspaper Online, January 30, 2019.
“New structural aspects of copper isotopes unveiled through the nuclear magnetic moment—Successful measurement by maximizing spinalignment of the RI beam—ʢʮ࣓‫ؾ‬Ϟʔϝϯτ͔Β෼͔ΔಔಉҐମͷ৽ͨͳ࢟—‫Ͱ·ݶۃ‬εϐϯ੔ྻ౓ΛߴΊͨ RI ϏʔϜΛ‫ۦ‬࢖ͯ͠ଌఆʹ੒ޭ—ʯʣ,” joint press-release from RIKEN and the University of Tokyo, January 30, 2019.
RIKEN HP: https://www.riken.jp/press/2019/20190130_2/ .
The Univ. of Tokyo HP: https://www.s.u-tokyo.ac.jp/ja/info/6251/ .
JICFuS HP: https://www.jicfus.jp/jp/190130pressrelease/ .

Outreach activities
H. Ueno, Special Exhibition of the International Year of the Periodic Table 2019ʢࠃࡍप‫ظ‬ද೥ಛผల 2019ʮཧԽֶ‫ॴڀݚ‬ͷχϗχ΢Ϝ໛‫ܕ‬Λͭ͘Ζ͏ʯʣ, Ehime Prefectural Science Museum, January 18–19, 2020.
ʮ‫֩ࢠݪ‬Λั·͑ͯޫͰ
A. Takamine, Interactive Event “RIKEN DAY: Let’s talk with researchers!” ʢཧ‫ ݚ‬DAYɿ‫ͱऀڀݚ‬࿩ͦ͏ʂΈΔʯʣ, Tokyo Science Museum, December 15, 2019.
H. Ueno, RIKEN Osaka Campus Open Day 2019, Suita, November 23, 2019.
H. Ueno, Kagakudo 100 Books 2019 Selection CommitteeʢՊֶಓ 100 ࡭ 2019 બॻҕһձ).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research DivisionHigh Energy Astrophysics Laborarory
1. Abstract

In the immediate aftermath of the Big Bang, the beginning of our universe, only hydrogen and helium existed. However, nuclear
fusion in the interior of stars and the explosion of supernovae in the universe over 13.8 billion years led to the evolution of a world
brimming with the many diﬀerent elements we have today. By using scientific satellites or balloons to observe X-rays and gamma-rays
emitted from celestial objects, we are observing the synthesis of the elements at their actual source. Our goal is to comprehensively
elucidate the scenarios for the formation of the elements in the universe, together with our research on sub-atomic physics through theuse of an accelerator.

2. Major Research Subjects(1) Nucleosynthesis in stars, supernovae, and neutron star mergers(2) Plasma and vacuum in extremely strong magnetism and gravity(3) Research and development of innovative X-ray and gamma-ray detectors

3. Summary of Research Activity

High Energy Astrophysics Laboratory started in April 2010. The goal of our research is to reveal the mechanism of nucleosynthesis and the evolution of elements in the universe, and to observe/discover exotic physical phenomena in extremely strong magnetic
and/or gravitational fields. We have observed supernova remnants, strongly magnetized neutron stars, pulsars, black holes and galaxies
with X-ray astronomical satellites, balloons and ground-based telescopes.
(1) Nucleosynthesis in the universe(1-1) XRISM
We have contributed to the XRISM (X-ray imaging and spectroscopy mission) mission for the launch in 2022. XRISM is therecovery mission of the ASTRO-H/Hitomi satellite, which was launched in February 2016 but lost by an accident one month after thelaunch. Hitomi carried four X-ray and gamma-ray detectors covering the 0.3–600 keV energy range. We, in collaboration with JAXA
(Japan Aerospace Exploration Agency), Tokyo Metropolitan University, Kanazawa University, Saitama University, NASA/GSFC etc.,
contributed to the soft X-ray spectrometer (SXS), which achieves unprecedented energy resolution (<7 eV) in the 0.3–12 keV energy
band with a low temperature micro calorimeter. We hoped to use SXS to discover many previously-unknown elemental lines in theuniverse and to measure the abundance of these elements, but this was not possible with Hitomi. The XRISM satellite carries almost
identical X-ray detectors as the Hitomi satellite, and is expected to carry out scientific observations that were not done with the Hitomi
mission.
(1-2) MAXI
From April 2018, High Energy Astrophysics Laboratory hosts MAXI (Monitor of All-sky X-ray Image) onboard International
Space Station (ISS), which was attached on ISS in 2009. MAXI is a RIKEN-lead project collaborating with JAXA and other universities. Since MAXI scans X-ray all-sky in 90 minutes, many transient objects including neutron star or blackhole binaries are found. Allof the data are going to public soon after they are taken, and almost all of the groups in high-energy phenomena rely on the MAXI data.
In 2018, we issued 34 alerts as ATEL (Astronomer’s Telegram) and 5 new blackhole candidates were found. To detect counterpartsof neutron star merger events (i.e. gravitational wave events), we have prepared an automatic searching system and keep watching
all-sky.
(1-3) Astrophysical Data Analysis
In parallel with the mission development/operations, we performed data analysis.
• We proved that the abundance ratios of the iron-peak elements in the Perseus cluster were consistent with the solar abundance. In
previous studies, overabundance of Cr, Mn, and Ni are reported, but Hitomi’s high spectroscopic data denied the overabundance.
The inter-galactic medium of the nearby cluster has similar abundance pattern of our galaxy.
• We have detected a mysterious hump in the spectrum of the neutronstar low-mass X-ray binary, Aquila X-1. The hump can beinterpreted as a recombination-edge of heavy elements (Cd) which were possibly produced by rp-process in X-ray bursts on theneutron star surface.
(2) Extremely strong magnetism and gravity
We have contributed to the NASA’s world-first X-ray polarimeter mission IXPE (Imaging X-ray Polarimeter Explorer). HighEnergy Astrophysics Laboratory is responsible for providing the gas electron multipliers (GEMs) to the IXPE mission: the GEM is a
key device of the X-ray polarimeter and produced based on our patent for space use. The IXPE satellite will be launched in the second
half of 2021. We have already provided the flight qualified GEMs to the project in FY2018, and have contributed to the detector
calibrations in FY2019.
By using the IXPE mission, we aim to proof the strong magnetism of Magnetars, which are one of the species of neutron stars
which have ultra-strong magnetic field B > 1011 T. In such ultra-strong magnetic field, higher-order diagrams, O(eB/m2 ), O(eB/m2 )2
etc., never eliminated in the QED perturbation theory. As the results, we observe newly-emerging phenomenon such as vacuum
polarization, vacuum birefringence, etc. If such exotic phenomena are detected, we sure that Magnetars have really ultra-strong- 270 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

magnetic field.
(3) Innovative X-ray and gamma-ray detectors
In collaboration with NASA Goddard Space Flight Center, we have developed and tested a hard X-ray polarimeter with a Time
Projection Chamber technique. This TPC polarimeter is one of candidates of the future satellite XPP (X-ray polarimeter Probe
mission) planned with an international consortium.
As an successor of the MAXI mission, we are also verifying the principle of a new concept, multiplexing lobster-eye (MuLE)
optics, to monitor the entire sky with a wide field-of-view for detecting and immediate reporting transient objects such as a neutronstar merger.

Members
Group Director
Toru TAMAGAWA
Research/Technical Scientist
Tatehiro MIHARA (Senior Research Scientist)
Contract Researcher
Takao KITAGUCHI
Visiting Researcher
Asami HAYATO (JSPS Fellow)
Visiting Scientists
Aya BAMBA (Univ. of Tokyo)
Teruaki ENOTO (Kyoto Univ.)
Naohisa INADA (NIT, Nara College)
Satoru KATSUDA (Saitama Univ.)
Tomoki KIMURA (Tohoku Univ.)
Motohide KOKUBUN (ISAS/JAXA)
Toru MISAWA (Shinshu Univ.)
Ikuyuki MITSUISHI (Nagoya Univ.)
Yujin NAKAGAWA (JAMSTEC)
Toshio NAKANO (JTEC Corporation)

Hirofumi NODA (Osaka Univ.)
Hirokazu ODAKA (Univ. of Tokyo)
Yuki OKURA (NAOJ/Nat’l Inst. of Natural Sci.)
Rohta TAKAHASHI (NIT, Tomakomai College)
Yoko TAKEUCHI (TIRI)
Yukikatsu TERADA (Saitama Univ.)
Harufumi TSUCHIYA (JAEA)
Masaki WAKABAYASHI (Jakulin Commercial Company LC)
Shin’ya YAMADA (Tokyo Metoropolitan University)

Student Trainees
Miho OKUBO (Tokyo University of Science)
Tomoshi TAKEDA (Tokyo University of Science)
Marina TSUTSUMI (Tokyo University of Science)

Keisuke UCHIYAMA (Tokyo University of Science)
Yuto YOSHIDA (Tokyo University of Science)
Yuuki WADA (Univ. of Tokyo)

List of Publications & Presentations
Publications[Original papers]
T. Ebisuzaki, J. Katori, J. Makino, A. Noda, H. Shinkai, and T. Tamagawa, “INO: Interplanetary network of optical lattice clocks,” Int. J.
Mod. Phys. D 29, id.1940002 (2020).
S. Oda, M. Shidatsu, S. Nakahira, T. Tamagawa, Y. Moritani, R. Itoh, Y. Ueda, H. Negoro, K. Makishima, N. Kawai, and T. Mihara,“X-ray and optical observations of the black hole candidate MAXI J1828-249,” Publ. Astron. Soc. Jpn. 71, id.108 (2019).
T. Kitaguchi, K. Black, T. Enoto, A. Hayato, J. Hill, W. Iwakiri, P. Kaaret, T. Mizuno, and T. Tamagawa, “A convolutional neural network
approach for reconstructing polarization information of photoelectric X-ray polarimeters,” Nucl. Instrum. Methods Phys. Res. A 942,
id.162389 (2019).
M. Kubota, T. Tamagawa, K. Makishima, T. Nakano, W. Iwakiri, M Sugizaki, and K. Ono, “An enigmatic hump around 30 keV in Suzaku
spectra of Aquila X-1 in the hard state,” Publ. Astron. Soc. Jpn. 71, id.33 (2019).
C. Hu, T. Mihara, M. Sugizaki, Y. Ueda, and T. Enoto, “Monitoring the superorbital period variation and spin period evolution of SMC
X-1,” Astrophys. J. 885, id.123 (2019).
E. Gotthelf, J. Halpern, J. Alford, T. Mihara, H. Negoro, N. Kawai, S. Dai, M. Lower, S. Johnston, M. Bailes, S. Oslowski, F. Camilo,
H. Miyasaka, and K. Madsen, “The 2018 x-ray and radio outburst of magnetar XTE J1810-197,” Astrophys. J. Lett. 874, id.L25 (2019).
Q. Abarr, M. Baring, B. Beheshtipour, M. Beilicke, G. de Geronimo, P. Dowkontt, M. Errando, V. Guarino, N. Iyer, F. Kislat, M. Kiss,
T. Kitaguchi, H. Krawczynski, J. Lanzi, S. Li, L. Lisalda, T. Okajima, M. Pearce, L. Press, B. Rauch, D. Stuchlik, H. Takahashi, J. Tang,
N. Uchida, A. West, P. Jenke, H. Krimm, A. Lien, C. Malacaria, J. Miller, and C. Wilson-Hodge, “Observations of a GX 301-2 apastronflare with the x-calibur hard x-ray polarimeter supported by NICER, the swift XRT and BAT, and fermi GBM,” Astrophys. J. 891, id.70(2020).
M. Ohno, et al., “Event-selection technique for the multi-layer Si -CdTe Compton camera onboard Hitomi,” Nucl. Instrum. Methods Phys.
Res. A 924, 327–331 (2019).

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Presentations[International conferences/workshops]
Y. Takeuchi (Oral), “Development and properties of 100 mm-square size LTCC-GEM,” The 6th International Conference on Micro Pattern
Gaseous Detectors (MPGD19), La Rochelle, France, May 5–10, 2019.
T. Kitaguchi (Poster), “A machine learning approach for reconstructing X-ray polarization information acquired with micro-pattern gas
polarimeters,” The 6th International Conference on Micro Pattern Gaseous Detectors (MPGD19), La Rochelle, France, May 5–10,
2019.
K. Uchiyama (Poster), “Irradiation test with heavy ions of fine-pitch LCP-GEMs for the IXPE satellite mission,” The 6th International
Conference on Micro Pattern Gaseous Detectors (MPGD19), La Rochelle, France, May 5–10, 2019.

[Domestic conferences/workshops]ࡾ‫ޱ( ߂ݐݪ‬಄ൃද), ʮશఱ X ઢ‫૷ࢹ؂‬ஔ MAXI ͷ 10 ೥ʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
ᜊ౻༾ (‫ޱ‬಄ൃද), ʮখ‫ܕ‬Ӵ੕౥ࡌΛ໨ࢦͨ͠ΨϯϚઢόʔετภޫ౓‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬,2019 ೥ 9 ݄ 17–20 ೔.
ߴ‫ޱ( ॆ߂ڮ‬಄ൃද), ʮߗ X ઢूޫภޫ‫ ܭ‬XL-Calibur ‫ݧ࣮ٿؾ‬ͷ 2021 ೥ϑϥΠτ΁޲͚ͨ४උঢ়‫گ‬ʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
။ᖒ༏ً (‫ޱ‬಄ൃද), ʮCMOS ΠϝʔδϟΛ༻͍ͨ X ઢภޫࡱ૾γεςϜͷ։ൃ IIIʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019
೥ 9 ݄ 17–20 ೔.
‫࢘܊‬मҰ (‫ޱ‬಄ൃද), ʮภޫ X ઢ‫؍‬ଌӴ੕ IXPE ͷਐ௙ঢ়‫ͱگ‬γϛϡϨʔγϣϯ΁ͷऔΓ૊Έʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ,໊‫ݹ‬԰େֶ, ΦϯϥΠϯ։࠵, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
಺ࢁ‫ܚ‬༞ (‫ޱ‬಄ൃද), ʮIXPE Ӵ੕౥ࡌ GEM ͷӉ஦ઢॏΠΦϯ΁ͷ଱ੑࢼ‫ݧ‬ʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ΦϯϥΠϯ։࠵, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
य़೔஌໌ (‫ޱ‬಄ൃද), ʮCMOS ΠϝʔδϟΛ༻͍ͨ X ઢภޫࡱ૾γεςϜͷ։ൃ IVʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ΦϯϥΠϯ։࠵, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
‫ۄ‬઒ప (‫ޱ‬಄ൃද), ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ΁ͷࢀՃ‫ݱ‬ঢ় (5)ʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘
͹, 2020 ೥ 3 ݄ 16–19 ೔.
ࢁ‫ޱ‬༑༸ (‫ޱ‬಄ൃද), ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ౥ࡌ X ઢ๬ԕ‫༻ڸ‬डಈ‫ܕ‬೤੍‫ޚ‬ૉࢠαʔϚϧγʔϧυͷ։ൃ (6)ʯʯ, ೔ຊఱจֶ
ձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
ࢁຊཾ࠸ (‫ޱ‬಄ൃද), ʮγϛϡϨʔγϣϯΛ༻͍ͨ IXPE Ӵ੕ʹΑΔ޿͕ͬͨఱମͷ X ઢภޫղੳख๏ͷ‫ڀݚ‬ʯʯ, ೔ຊఱจֶձ
2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
ി಺߁ี (‫ޱ‬಄ൃද), ʮCMOS ΠϝʔδηϯαΛ༻͍ͨߗ X ઢࡱ૾ภޫ‫ܭ‬ͷ։ൃ IIʯʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ,ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
ߴ‫ޱ( ॆ߂ڮ‬಄ൃද), ʮߗ X ઢภޫ‫؍‬ଌ࣮‫ ݧ‬XL-Calibur ‫ٿؾ‬ͷ 2021 ೥ϑϥΠτ΁޲͚ͨ४උঢ়‫گ‬ʯʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
ᖒ໺ୡ࠸ (‫ޱ‬಄ൃද), ʮॏྗ೾‫ ݯ‬X ઢରԠఱମ୳ࠪ‫ܭ‬ը Kanazawa-SAT3 ϑϥΠτϞσϧͷ෼ޫੑೳධՁʯʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
ੴ࡚‫ۍ‬ঘ (‫ޱ‬಄ൃද), ʮX ઢ෼ޫࡱ૾Ӵ੕ XRISM ౥ࡌ Resolve ͷ։ൃͷ‫ݱ‬ঢ় Vʯʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
ࡾ‫ޱ( ߂ݐݪ‬಄ൃද), ʮMAXI/GSC ʹΑΔ ۜՏ‫ܥ‬ϋϩʔͷ BH ࿈੕ MAXI J0637-430 ͷൃ‫ͱݟ‬, 2019 ೥౓‫ޙ‬൒ͷಥൃ‫ݱ‬৅ʯʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
ઙҪ࿨ඒ (‫ޱ‬಄ൃද), ʮதੑࢠ੕ͱͷ௿࣭ྔ X ઢ࿈੕ͷ௕‫ظ‬มಈʹ͍ͭͯ IIʯʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
ߴౢ૱ (‫ޱ‬಄ൃද), ʮʮ͘͢͟ʯӴ੕ʹΑΔ߱ணதੑࢠ੕ SMC X-1 ͷ޿͕ͬͨమًઢͷղੳͱͦͷ‫ي‬ಓɾ௒‫ي‬ಓҐ૬ґଘੑʯʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ஜ೾େֶ, ΦϯϥΠϯ։࠵, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
‫ۄ‬઒ప (‫ޱ‬಄ൃද), ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ΁ͷࢀՃ‫ݱ‬ঢ় (4)ʯ, ೔ຊఱจֶձ 2019 ೥ळ‫ق‬೥ձ, ‫۽‬ຊେֶ, ‫۽‬ຊ, 2019 ೥ 9 ݄
11–13 ೔.
ࡾੴҮ೭ (‫ޱ‬಄ൃද), ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ౥ࡌ X ઢ๬ԕ‫༻ڸ‬डಈ‫ܕ‬೤੍‫ޚ‬ૉࢠαʔϚϧγʔϧυͷ։ൃ (5)ʯ, ೔ຊఱจֶձ
2019 ೥ळ‫ق‬೥ձ, ‫۽‬ຊେֶ, ‫۽‬ຊ, 2019 ೥ 9 ݄ 11–13 ೔.
ࢁຊཾ࠸ (‫ޱ‬಄ൃද), ʮγϛϡϨʔγϣϯΛ༻͍ͨ IXPE Ӵ੕ʹΑΔ X ઢภޫղੳख๏ͷ‫ڀݚ‬ʯ, ೔ຊఱจֶձ 2019 ೥ळ‫ق‬೥ձ,‫۽‬ຊେֶ, ‫۽‬ຊ, 2019 ೥ 9 ݄ 11–13 ೔.
๺‫وޱ‬༤ (‫ޱ‬಄ൃද), ʮ‫ػ‬ցֶशΛ༻͍ͨඈ੻ը૾ॲཧʹΑΔޫిࢠ௥੻‫̭ܕ‬ઢภޫ‫ܭ‬ͷ‫্͓޲౓ײ‬Αͼ IXPE Ӵ੕σʔλ΁ͷԠ༻ʯ, ೔ຊఱจֶձ 2019 ೥ळ‫ق‬೥ձ, ‫۽‬ຊେֶ, ‫۽‬ຊ, 2019 ೥ 9 ݄ 11–13 ೔.
ੴ࡚‫ۍ‬ঘ (‫ޱ‬಄ൃද), ʮX ઢ෼ޫࡱ૾Ӵ੕ XRISM ౥ࡌ Resolve ͷ։ൃͷ‫ݱ‬ঢ় IVʯ, ೔ຊఱจֶձ 2019 ೥ळ‫ق‬೥ձ, ‫۽‬ຊେֶ, ‫۽‬ຊ,2019 ೥ 9 ݄ 11–13 ೔.
খߴ༟࿨ (‫ޱ‬಄ൃද), ʮCMOS ΠϝʔδηϯαΛ༻͍ͨߗ X ઢࡱ૾ภޫ‫ܭ‬ͷ։ൃʯ, ೔ຊఱจֶձ 2019 ೥ळ‫ق‬೥ձ, ‫۽‬ຊେֶ, ‫۽‬ຊ, 2019 ೥ 9 ݄ 11–13 ೔.
େ‫ٱ‬อඒึ (‫ޱ‬಄ൃද), ʮγϯΫϩτϩϯ์ࣹޫΛ༻͍ͨߴΤωϧΪʔ X ઢภޫ‫ܭ‬ͷੑೳධՁʯ, ೔ຊఱจֶձ 2019 ೥ळ‫ق‬೥ձ,‫۽‬ຊେֶ, ‫۽‬ຊ, 2019 ೥ 9 ݄ 11–13 ೔.
ߴ‫ޱ( ॆ߂ڮ‬಄ൃද), ʮߗ̭ઢภޫ‫؍‬ଌ࣮‫ ݧ‬X(L)-Calibur ‫ٿؾ‬ͷ 2018 ೥ͷ‫؍‬ଌ݁Ռͱ 2021 ೥ϑϥΠτ΁޲͚ͨ४උঢ়‫گ‬ʯ, ೔ຊఱจֶձ 2019 ೥ळ‫ق‬೥ձ, ‫۽‬ຊେֶ, ‫۽‬ຊ, 2019 ೥ 9 ݄ 11–13 ೔.

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෢ా๎ࢤ (‫ޱ‬಄ൃද), ʮAPV25/SRS Λར༻ͨ͠ TPC X ઢภޫ‫ܭ‬ͷ։ൃͱภޫ‫؍‬ଌʹ࠷దͳ APV 25 ઃఆͷௐࠪʯ, ϚΠΫϩύλʔϯΨε‫ݕ‬ग़‫ & ث‬ΞΫςΟϒഔ࣭ TPC ߹ಉ‫ڀݚ‬ձ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 12 ݄ 6–7 ೔.
٢ా༐ొɾࠤ౻޺थ (‫ޱ‬಄ൃද), ʮ௒খ‫ܕ‬Ӵ੕౥ࡌ༻ GEM X ઢ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ϚΠΫϩύλʔϯΨε‫ݕ‬ग़‫ & ث‬ΞΫςΟϒഔ࣭
TPC ߹ಉ‫ڀݚ‬ձ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 12 ݄ 6–7 ೔.
पᅵً (ϙελʔൃද), ʮࡱ૾ૉࢠͷ਺Λେ෯ʹ࡟‫͢ݮ‬ΔଟॏԽϩϒελʔΞΠ X ઢ ޫֶ‫ܥ‬ͷ։ൃ࣮ূʯ, JAXA Ӊ஦Պֶ‫ॴڀݚ‬,૬໛‫ݪ‬, 2020 ೥ 1 ݄ 8–9 ೔.
‫࢘܊‬मҰ (ϙελʔൃද), ʮIXPE Ӵ੕ʹΑΔ޿͕ͬͨఱମͷ‫؍‬ଌγϛϡϨʔγϣϯʯ, JAXA Ӊ஦Պֶ‫ॴڀݚ‬, ૬໛‫ݪ‬, 2020 ೥ 1 ݄
8–9 ೔.
ࡾੴҮ೭ (ϙελʔൃද), ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ౥ࡌʹ޲͚ͨ๬ԕ‫༻ڸ‬αʔϚϧ γʔϧυͷ։ൃʯ, JAXA Ӊ஦Պֶ‫ॴڀݚ‬, ૬໛‫ݪ‬, 2020 ೥ 1 ݄ 8–9 ೔.
ߴ‫( ॆ߂ڮ‬ϙελʔൃද), ʮߗ X ઢूޫภޫ‫ ܭ‬X(L)-Calibur ‫ݧ࣮ٿؾ‬ͷ 2018 ೥ϑϥΠτͱকདྷ‫ܭ‬ըʯ, JAXA Ӊ஦Պֶ‫ॴڀݚ‬, ૬໛‫ݪ‬, 2020 ೥ 1 ݄ 8–9 ೔.
‫ۄ‬઒ప (ϙελʔൃද), ʮX ઢภޫ‫؍‬ଌӴ੕ IXPEʯ, JAXA Ӊ஦Պֶ‫ॴڀݚ‬, ૬໛‫ݪ‬, 2020 ೥ 1 ݄ 8–9 ೔.
ੴ࡚‫ۍ‬ঘ (ϙελʔൃද), ʮX ઢ෼ޫࡱ૾Ӵ੕ (XRISM) ౥ࡌ Resolve ͷ։ൃঢ়‫گ‬ʯ, JAXA Ӊ஦Պֶ‫ॴڀݚ‬, ૬໛‫ݪ‬, 2020 ೥ 1 ݄
8–9 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Superheavy Element Research Group
1. Abstract
The elements with their atomic number Z > 103 are called as trans-actinide or superheavy elements. This group has been studying
the physical and chemical properties of superheavy elements. They must be produced by artificially for the scientific study utilizing
the accelerators in RIBF. Two teams lead the study of the superheavy elements. Superheavy Element Production Team studies various
methods of eﬃcient production of the superheavy elements and their physical and chemical properties. Superheavy Element Device
Development Team develops the main experimental device, i.e., the gas-filled recoil ion separator, GARIS.
The synthesis of elements having atomic numbers over 119 will be attempted with the aim of establishing nuclear synthesis
technology that reaches the “island of stability” where the lifetime of atomic nuclei is expected be prolonged significantly. With theaim of constructing an ultimate nuclear model, maximum utilization will be made of key experimental devices which become fully
operational in order to conduct research for the syntheses of element 119 and 120.

2. Major Research Subjects
Superheavy Element Production Team
(1) Searching for new elements(2) Spectroscopic study of the nucleus of heavy elements(3) Chemistry of superheavy elements(4) Study of a reaction mechanism for fusion process
Superheavy Element Device Development Team
(5) Maintenance of GARIS, GARIS-II and development of new gas-filled recoil ion separator GARIS-III(6) Maintenance and development of detector and DAQ system for GARIS, GARIS-II and GARIS-III(7) Maintenance and development of target system for GARIS, GARIS-II and GARIS-III

3. Summary of Research Activity(1) Searching for new elements
To expand the periodic table of elements and the nuclear chart, we will search for new elements.
(2) Spectroscopic study of the nucleus of heavy elements
Using the high sensitivity system for detecting the heaviest element, we plan to perform a spectroscopic study of nuclei of theheavy elements.
(3) Chemistry of superheavy elements
Study of chemistry of the trans-actinide (superheavy element) has just started world-wide, making it a new frontier in the field ofchemistry. Relativistic eﬀects in chemical property are predicted by many theoretical studies. We will try to develop this new field.
(4) Study of a reaction mechanism for fusion process
Superheavy elements have been produced by complete fusion reaction of two heavy nuclei. However, the reaction mechanism of
the fusion process is still not well understood theoretically. When we design an experiment to synthesize nuclei of the superheavy
elements, we need to determine a beam-target combination and the most appropriate reaction energy. This is when the theory becomes
important. We will try to develop a reaction theory useful in designing an experiment by collaborating with the theorists.
(5) Research Highlight
The discovery of a new element is one of the exciting topics both for nuclear physicists and nuclear chemists. The elements with
their atomic number Z > 103 are called as trans-actinides or superheavy elements. The chemical properties of those elements have notyet been studied in detail. Since those elements do not exist in nature, they must be produced by artificially, by using nuclear reactions
for the study of those elements. Because the production rate of atoms of those elements is extremely small, an eﬃcient production andcollection are key issues of the superheavy research. In our laboratory, we have been trying to produce new elements, studying thephysical and chemical properties of the superheavy elements utilizing the accelerators in RIKEN.
Although the Research Group for Superheavy element has started at April 2013, the Group is a renewal of the Superheay Element
Laboratory started at April 2006, based on a research group which belonged to the RIKEN accelerator research facility (RARF), andhad studied the productions of the heaviest elements. The main experimental apparatus is a gas-filled recoil ion separator GARIS. The
heaviest elements with their atomic numbers, 107 (Bohrium), 108 (Hassium), 109 (Meitnerium), 110 (Darmstadtium), 111 (Roentogenium), and 112 (Copernicium) were discovered as new elements at Helmholtzzentrum für Schwerionenforschung GmbH (GSI),
Germany by using 208 Pb or 209 Bi based complete fusion reactions, so called “cold fusion” reactions. We have made independentconfirmations of the productions of isotopes of 108th, 110th, 111th, and 112th elements by using the same reactions performed at GSI.
After these work, we observed an isotope of the 113th element, 278 113, in July 2004, in April, 2005, and in August 2012. The isotope,
278
113, has both the largest atomic number, (Z = 113) and atomic mass number (A = 278) which have determined experimentally
among the isotopes which have been produced by cold fusion reactions. We could show the world highest sensitivity for production
and detection of the superheavy elements by these observations. Our results that related to 278 113 has been recognized as a discovery- 274 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

of new element by a Joint Working Party of the International Union of Pure and Applied Chemistry (IUPAC) and International Union
of Pure and Applied Physics (IUPAP). Finally, we named the 113th element as “Nihonium.”
We decided to make one more recoil separator GARIS-II, which has an acceptance twice as large as existing GARIS, in order torealize higher sensitivity. The design of GARIS-II has finished in 2008. All fabrication of the separator will be finished at the end of
fiscal year 2008. It has been ready for operation after some commissioning works.
Preparatory work for the study of the chemical properties of the superheavy elements has started by using the gas-jet transportsystem coupled to GARIS. The experiment was quite successful. The background radioactivity of unwanted reaction products has beenhighly suppressed. Without using the recoil separator upstream the gas-jet transport system, large amount of unwanted radioactivity
strongly prevents the unique identification of the event of our interest. This new technique makes clean and clear studies of chemistryof the heaviest elements promising.
The spectroscopic study of the heaviest elements has started by using alpha spectrometry. New isotope, 263 Hs (Z = 108), which
has the smallest atomic mass number ever observed among the Hassium isotopes, had discovered in the study. New spectroscopic
information for 264 Hs and its daughters have obtained also. The spectroscopic study of Rutherfordium isotope 261 Rf (Z = 104) has
done and 1.9-s isomeric state has directly produced for the first time.
Preparatory works for the study of the new superheavy elements with atomic number 119 and 120 have started in 2013. We
measured the reaction products of the 248 Cm (48 Ca, xn)296- x Lv (Z = 116) previously studied by Frelov Laboratory of Nuclear Reaction,
Russia, and GSI. We observed 5 isotopes in total which tentatively assigned to 293 Lv, and 292 Lv.

MemberDirector
Kosuke MORITA

List of Publications & Presentations
Publications[Original papers]
T. Tanaka, K. Morita, K. Morimoto, D. Kaji, H. Haba, R. A. Boll, N. T. Brewer, S. Van Cleve, D. J. Dean, S. Ishizawa, Y. Ito, Y. Komori,K. Nishio, T. Niwase, B. C. Rasco, J. B. Roberto, K. P. Rykaczewski, H. Sakai, D. W. Stracener, and K. Hagino, “Study of quasielastic
barrier distributions as a step towards the synthesis of superheavy elements with hot fusion reactions,” Phys. Rev. Lett. 124, 052502-1–
052502-6 (2020).

Presentations[International conferences/workshops]
K. Morita (invited), “Superheavy element search at RIKEN,” The 4th International Symposium on Superheavy Elements (SHE2019),
Hakone, Japan, December 1–5, 2019.
S. Sakaguchi (oral), “Perspective in the super heavy element research,” Joint Kickoﬀ Meeting of JSPS/NRF/NSFC A3 Foresight Program“Nuclear physics in the 21st century,” Kobe, Japan, December 6–7, 2019.

Awards৿ాߒհ, ʮ113 ൪‫ݩ‬ૉͷൃ‫ʹݟ‬ΑΔ์ࣹԽֶ΁ͷߩ‫ݙ‬ʯ, ୈ 63 ճ೔ຊ์ࣹԽֶ, ໦ଜ৆.

Others৿ాߒհ, ཧԽֶ‫ ॴڀݚ‬Ұൠެ։, ཧԽֶ‫ ॴڀݚ‬കଠ࿠ϗʔϧ, ࿨ޫ, 2019 ೥ 04 ݄ 20 ೔.
৿ాߒհ, ֩ԽֶՆͷֶߍ, ༝෍Ӄ ༝෍τϐΞ, ༝෍, 2019 ೥ 09 ݄ 13 ೔.
৿ాߒհ,ʮ৽‫ݩ‬ૉͷ୳ࡧʯ, ࡨମԽֶ౼࿦ձࢢຽߨ࠲, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2019 ೥ 09 ݄ 21 ೔.
৿ాߒհ,ʮ113 ൪‫ݩ‬ૉͷൃ‫ʹݟ‬ΑΔ์ࣹԽֶ΁ͷߩ‫ݙ‬ʯ, ೔ຊ์ࣹԽֶֶձ, ͍Θ͖, 2019 ೥ 09 ݄ 25 ೔.
৿ాߒհ,ʮαΠΤϯεΧϑΣ in SAGAʯ, ࢈‫ۀ‬࿑ಇ෦ ΋ͷͮ͘Γ࢈‫ۀ‬՝, Պֶ‫ؗ‬, ௗ੘, 2019 ೥ 09 ݄ 28 ೔.
৿ాߒհ,ʮ৽‫ݩ‬ૉͷ୳ࡧʯ, ࡛‫ۄ‬େֶʢཧֶ෦ʣΉͭΊࡇ, ࡛‫ۄ࡛ ۄ‬େֶཧֶ෦, ͍ͨ͞·, 2019 ೥ 11 ݄ 02 ೔.
৿ాߒհ, IYPT ดձࣜ, ౦‫ ژ‬౦‫ژ‬ϓϦϯεϗςϧ, ౦‫ژ‬, 2019 ೥ 12 ݄ 05 ೔.
৿ాߒհ,ʮ৽‫ݩ‬ૉͷ୳ࡧʯ, େ෼‫ؔػڀݚݧࢼݝ‬, େ෼‫ཱݝݝ‬ਤॻ‫ؗ‬, େ෼, 2019 ೥ 11 ݄ 16 ೔.
৿ాߒհ,ʮ෱ҪαΠΤϯεϑΣελʯ, ෱Ҫ‫ڭݝ‬ҭி, ෱Ҫࢢ AOSSA, ෱Ҫ, 2019 ೥ 02 ݄ 11 ೔.
৿ాߒհ,ʮ೔ຊͷ͍͢͝Պֶऀʯ, ே೔খֶੜ৽ฉ, 2019 ೥ 10 ݄ 07 ೔.
৿ాߒհ,ʮ113 ൪ɾ119 ൪‫ݩ‬ૉ΁ͷࢥ͍ʯ, ຖ೔৽ฉ, 2019 ೥ 08 ݄ 22 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Superheavy Element Research Group
Superheavy Element Production Team
1. Abstract

The elements with atomic number Z ≥ 104 are called as trans-actinide or superheavy elements (SHEs). Superheavy Element
Production Team investigates synthesis mechanisms of SHEs, nuclear properties of SHE nuclei, and chemical properties of SHEs
mainly in collaboration with Superheavy Element Devise Development Team and Nuclear Chemistry Research Team of RIKEN
Nishina Center.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Search for new superheavy elements
Decay spectroscopy of the heaviest nuclei
Study of reaction mechanisms for production of the heaviest nuclei
Study of chemical properties of the heaviest elements

Summary of Research Activity(1) Search for new superheavy elements
In November, 2016, the 7th period of the periodic table was completed with the oﬃcial approval of four new elements, nihonium(Nh, atomic number Z = 113), moscovium (Mc, Z = 115), tennessine (Ts, Z = 117), and oganesson (Og, Z = 118) by International
Union of Pure and Applied Chemistry (IUPAC). We have started to search for new elements to expand the chart of the nuclides toward
to the island of stability and the periodic table of the elements toward the 8th period of the periodic table. Since June, 2017, RIKEN
heavy-ion Linear ACcelerator (RILAC) has been shut down for its upgrade until the end of 2019. During this long-term break, tocontinue SHE studies at RIBF, we moved GAs-filled Recoil Ion Separator II (GARIS II) from the irradiation room of RILAC to theE6 room of RIKEN Ring Cyclotron (RRC). In December 2017, the RRC + GARIS II setup became ready for SHE studies. We first
conducted the commissioning of the RRC + GARIS II setup in the nat La + 51 V, 159 Tb + 51 V, and 208 Pb + 51 V reactions. Then, we
started to search for new element, element 119 in the 248 Cm + 51 V reaction in January, 2018. In 2019, we continued to search forelement 119 in the 248 Cm + 51 V reaction. We also developed the new separator GARIS III on the beam line of the upgraded RILAC,
i.e. Superconducting RIKEN heavy-ion Linear ACcelerator (SRILAC). The SRILAC + GARIS III setup will be ready for the SHE
experiments in 2020.
(2) Decay spectroscopy of the heaviest nuclei
We developed a novel detector, referred to as an “α-TOF detector,” for correlated measurements of atomic masses and decay
properties of low-yield, short-lived radioactive isotopes using a multi-reflection time-of-flight mass spectrograph. By correlating
measured time-of-flight signals with decay events, it can suppress background events and obtain accurate, high-precision mass andhalf-life values even in cases of very low event rates. An oﬄine test of the α-TOF detector showed that the time-of-flight detection
eﬃciency for 5.48 MeV α-particles is more than 90% and yields a time resolution of 250.6(68) ps and an α-energy resolution of
141.1(9) keV.
(3) Study of reaction mechanisms for production of the heaviest nuclei
SHE nuclei have been produced by complete fusion reactions of two heavy nuclei. However, the reaction mechanism of thefusion process is still not well understood both theoretically and experimentally. We measured excitation functions for the quasielastic
scattering of the 248 Cm+22 Ne, 248 Cm+26 Mg, and 238 U+48 Ca reactions using GARIS at RILAC. The quasielastic barrier distributions
were successfully extracted for these systems, and compared with coupled-channels calculations. It was found that the results can beutilized to locate the optimal energy for the future searches for undiscovered superheavy nuclei.
(4) Study of chemical properties of the heaviest elements
Chemical characterization of newly-discovered SHEs is an extremely interesting and challenging subject in modern nuclear andradiochemistry. In collaboration with Nuclear Chemistry Research Team of RIKEN Nishina Center, we are developing SHE production systems as well as rapid single-atom chemistry apparatuses for chemistry studies of SHEs. We installed a gas-jet transportsystem to the focal plane of GARIS at RILAC. This system is a promising approach for exploring new frontiers in SHE chemistry: thebackground radiations from unwanted products are strongly suppressed, the intense primary heavy-ion beam is absent in the gas-jet
chamber, and hence the high gas-jet extraction yield is attained. Furthermore, the beam-free conditions make it possible to investigate
new chemical systems. In 2019, we continued to develop an ultra-rapid gas-chromatograph apparatus at the focal plane of GARIS forthe gas chemistry of SHEs. This apparatus consists of an RF carpet gas cell and a cryo-gas-chromatograph column with a Si detector
array. For the aqueous chemistry, we also developed a flow solvent extraction apparatus which consisted of a continuous dissolution
apparatus, a flow extraction apparatus, and a liquid scintillation counter.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Members
Team Leader
Hiromitsu HABA
Research & Development Scientist
Daiya KAJI
Special Postdoctoral Researcher
Tomohiro HAYAMIZU
Visiting Scientists
Satoshi ADACHI (Kyushu Univ.)
Marc ASFARI (Inst. Pluridisciplinaire Hubert Curien)
Mahananda DASGUPTA (Australian Nat’l Univ.)
Olivier DORVAUX (Strasbourg Univ.)
Benoit Jean-Paul GALL (Strasbourg Univ./Inst. Pluridisciplinaire Hubert Curien)
Zaiguo GAN (Inst. of Modern Phys.)
Shintaro GO (Kyushu Univ.)
David HINDE (The Australian Nat’l Univ.)
Student Trainees
Masato HIGASHI (Kyushu Univ.)
Tamito KAI (Kyushu Univ.)
Kieran KESSACI (IPHC Strasbourg/Strasbourg Univ.)
Ikuto MURAKAMI (Kyushu Univ.)
Yuto NAGATA (Kyushu Univ.)

Minghui HUANG (Inst. of Modern Phys.)
Hiroyuki KOURA (JAEA)
Daisuke NAGAE (Kyushu Univ.)
Satoshi SAKAGUCHI (Kyushu Univ.)
Mirei TAKEYAMA (Yamagata Univ.)
Masaomi TANAKA (Kyushu Univ.)
Taiki TANAKA (The Australian Nat’l Univ.)
Huabin YANG (Inst. of Modern Phys.)Zhiyuan ZHANG (Inst. of Modern Phys.)
Natsuki NAITO (Kyushu Univ.)
Mako OSADA (Kyushu Univ.)
Kazuya SHIRASAKA (Kyushu Univ.)
Yoshihide SUEKAWA (Kyushu Univ.)

List of Publications & Presentations
Publications[Original papers]
S. Ahmed, E. Altiere, T. Andalib, M. J. Barnes, B. Bell, C. P. Bidinosti, Y. Bylinsky, J. Chak, M. Das, C. A. Davis, F. Fischer, B. Franke,
M. T. W. Gericke, P. Giampa, M. Hahn, S. Hansen-Romu, K. Hatanaka, T. Hayamizu, B. Jamieson, D. Jones, K. Katsika, S. Kawasaki,
T. Kikawa, W. Klassen, A. Konaka, E. Korkmaz, F. Kuchler, L. Kurchaninov, M. Lang, L. Lee, T. Lindner, K. W. Madison, J. Mammei,
R. Mammei, J. W. Martin, R. Matsumiya, E. Miller, T. Momose, R. Picker, E. Pierre, W. D. Ramsay, Y. -N. Rao, W. R. Rawnsley,
L. Rebenitsch, W. Schreyer, S. Sidhu, S. Vanbergen, W. T. H. van Oers, Y. X. Watanabe, and D. Yosifov, “Fast-switching magnet
serving a spallation-driven ultracold neutron source,” Phys. Rev. Accel. Beams 22, 102401-1–16 (2019).
T. Tanaka, K. Morita, K. Morimoto, D. Kaji, H. Haba, R. A. Boll, N. T. Brewer, S. Van Cleve, D. J. Dean, S. Ishizawa, Y. Ito, Y. Komori,K. Nishio, T. Niwase, B. C. Rasco, J. B. Roberto, K. P. Rykaczewski, H. Sakai, D. W. Stracener, and K. Hagino, “Fusion dynamics for
hot fusion reactions to synthesize superheavy nuclei revealed in quasielastic barrier distributions,” Phys. Rev. Lett. 124, 052502-1–96(2020).
Y. Wang, Y. Wittwer, J. Zhang, J. Yang, H. Haba, Y. Komori, T. Yokokita, S. Cao, F. Fan, R. Eichler, A. Türler, and Z. Qin, “Massspectrometric speciation of metal-carbonyls in the gas phase,” PSI Annual Report 2018, Laboratory of Radiochemistry, 13–14 (2019).
Y. Kasamatsu, N. Kondo, K. Nakamura, Y. Kuboki, H. Ninomiya, Y. Shigekawa, E. Watanabe, Y. Yasuda, K. Toyomura, M. Nagase,
T. Yokokita, Y. Komori, H. Haba, T. Yoshimura, H. Itabashi, and A. Shinohara, “Solvent extraction of Zr and Hf from HCl by Aliquat
336 using a flow-type extraction apparatus toward online chemical studies of element 104, rutherfordium,” Solv. Extr. Ion Exch 38,
318–327 (2020).
T. Niwase, M. Wada, P. Schury, H. Haba, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Miyatake, K. Morimoto, K. Morita, M. Rosenbusch,
H. Wollnik, T. Shanley, and Y. Benari, “Development of an “α-TOF” detector for correlated measurement of atomic masses and decay
properties,” Nucl. Instrum. Methods Phys. Res. A 953, 163198-1–8 (2020).
Y. Sakemi, H. Nagahama, T. Hayamizu, N. Ozawa, K. S. Tanaka, K. Harada, A. Uchiyama, and J. Tsutsumi, “Present status of fundamental
symmetry experimental project with laser cooled heavy elements,” CNS Annual Report 2018, 23–24 (2020).
N. Ozawa, H. Nagahama, T. Hayamizu, J. Tsutsumi, K. S. Tanaka, K. Harada, A. Uchiyama, and Y. Sakemi, “Development of a novelsurface ionizer for the electron EDM measurement using francium,” CNS Annual Report 2018, 25–26 (2020).

[Review articles]
H. Haba, “The rewards and challenges of expanding the periodic table,” Chem. Eng. News, August 5, 36–37 (2019).
Ӌ৔޺ޫ, ʮୈ 8 प‫ظ‬ͷ৽‫ݩ‬ૉΛ‫ٻ‬Ίͯʯ, ์ࣹԽֶ 40, 14–20 (2019).
Ӌ৔޺ޫ, ʮ೔ຊͷ‫ʹऀڀݚ‬ΑΔ৽‫ݩ‬ૉͷ୳ࡧͱप‫ظ‬දͷ։୓—χοϙχ΢Ϝ, 93 ൪‫ݩ‬ૉ, χϗχ΢Ϝɻ͞ΒͳΔ৽‫ݩ‬ૉΛ‫ٻ‬Ίͯ—ʯ, Խֶͱ޻‫ ۀ‬72, 944–945 (2019).

[Books]- 277 -

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๛ౢް࢙, Ӌ৔޺ޫ, ʮ௒ॏ‫ݩ‬ૉԽֶ–༹ӷԽֶʯ, in ʮϑϩϯςΟΞγϦʔζ 2 ௒ॏ‫ݩ‬ૉԽֶͷ࠷લઢʯ, Ӭ໨་Ұ࿠ʢฤஶʣ, pp. 41–48,
೔ຊ์ࣹԽֶձ, 2019 ೥ 9 ݄ 1 ೔.

[Proceedings]
H. Haba for RIKEN SHE Collaboration, “Present status and perspectives of SHE researches at RIKEN,” in Proceedings of the International
Symposium on Exotic Nuclei, Petrozavodsk, Russia, 10–15 September 2018, Yu. E. Penionzhkevich, Yu. G. Sobolev (Eds.), (World
Scientific Publishing Co. Pte. Ltd., 2020), pp. 192–199.

Presentations[International conferences/workshops]
H. Haba (invited), “Production and applications of radioisotopes at RIKEN RI Beam Factory,” SHE Science Symposium, Oak Ridge,
USA, May 30, 2019.
H. Haba (invited), “Synthesis and chemistry of new elements at RIKEN,” 9th European Chemistry Congress, Berlin, Germany, June
17–18, 2019.
A. Yakushev, L. Lens, Ch. E. Düllmann, M. Asai, M. Block, H. Brand, H. M. David, J. Despotopulos, A. Di Nitto, K. Eberhardt, U. Forsberg, P. Golubev, M. Götz, S. Götz, H. Haba, L. Harkness-Brennan, W. Hartmann, R. -D. Herzberg, D. Hinde, J. Hoﬀmann, A. Hübner,
E. Jäger, M. Jourdan, D. Judson, J. Khuyagbaatar, B. Kindler, Y. Komori, J. Konki, J. V. Kratz, J. Krier, N. Kurz, M. Laatiaoui,
S. Lahiri, B. Lommel, M. Maiti, A. Mistry, Ch. Mokry, K. Moody, Y. Nagame, J. P. Omtvedt, P. Papadakis, V. Pershina, T. Reich,
D. Rudolph, J. Runke, L. Samiento, T. K. Sato, M. Schädel, P. Scharrer, B. Schausten, D. Shaughnessy, J. Steiner, P. Thörle-Pospiech,
A. Toyoshima, N. Trautmann, K. Tsukada, J. Uusitalo, K. -O. Voss, A. Ward, M. Wegrzecki, N. Wiehl, E. Williams, and V. Yakusheva(invited), “Chemical studies of superheavy elements at a recoil separator, with a focus on Fl,” 6th International Conference on theChemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
M. Götz, Ch. E. Düllmann, A. Yakushev, M. Asai, J. Ballof, A. Di Nitto, K. Eberhardt, S. Götz, H. Haba, E. Jäger, Y. Kaneya, Y. Komori,
J. V. Kratz, J. Krier, B. Lommel, A. Mitsukai, Y. Nagame, T. K. Sato, A. Toyoshima, K. Tsukada, V. Wolter, and V. Yakusheva (poster),“In-situ synthesis of volatile transition metal carbonyl complexes with short-lived radioisotopes,” 6th International Conference on theChemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
Z. Qin, Y. Wang, S. Cao, J. Zhang, J. Yang, H. Haba, F. Fan, Y. Komori, T. Yokokita, K. Morimoto, D. Kaji, Y. Wittwer, R. Eichler,
and A. Türler (poster), “The study of rhenium pentacarbonyl complexes using single-atom chemistry in gas phase,” 6th International
Conference on the Chemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
Y. Wang, Y. Wittwer, J. Zhang, J. Yang, H. Haba, Y. Komori, T. Yokokita, S. Cao, F. Fan, R. Eichler, A. Türler, and Z. Qin (oral), “Thespecies identification of Mo, W, and Re carbonyl complexes with laserablation time-of-flight mass-spectrometry,” 6th International
Conference on the Chemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
L. Lens, A. Yakushev, Ch. E. Düllmann, M. Asai, M. Block, H. Brand, M. Dasgupta, H. M. David, J. Despotopulos, A. Di Nitto,
K. Eberhardt, M. Götz, P. Golubev, S. Götz, H. Haba, L. Harkness-Brennan, F. P. Heßberger, R. -D. Herzberg, D. Hinde, J. Hoﬀmann,
A. Hübner, E. Jäger, D. Judson, J. Khuyagbaatar, B. Kindler, Y. Komori, J. Konki, J. V. Kratz, J. Krier, N. Kurz, M. Laatiaoui, S. Lahiri,
B. Lommel, M. Maiti, A. K. Mistry, C. Mokry, K. Moody, Y. Nagame, J. P. Omtvedt, P. Papadakis, V. Pershina, A. Roth, D. Rudolph,
J. Runke, L. Sarmiento, M. Schädel, P. Scharrer, T. Sato, D. Shaughnessy, B. Schausten, J. Steiner, P. Thörle-Pospiech, N. Trautmann,
K. Tsukada, J. Uusitalo, A. Ward, M. Wegrzecki, E. Williams, N. Wiehl, and V. Yakusheva (poster), “Optimizations of the TASCACOMPACT setup towards chemical studies of nihonium (element 113),” 6th International Conference on the Chemistry and Physics of
the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
T. Niwase, M. Wada, P. Schury, Y. Ito, S. Kimura, D. Kaji, M. Rosenbusch, Y. Watanabe, Y. Hirayama, H. Miyatake, J. Y. Moon,
H. Ishiyama, K. Morimoto, H. Haba, T. Tanaka, S. Ishizawa, A. Takamine, K. Morita, and H. Wollnik (poster), “Development and first
results from a novel “α-ToF” detector used with a multi-reflection time-of-flight mass spectrograph,” 6th International Conference on
the Chemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
T. Tanaka, K. Morita, K. Morimoto, D. Kaji, H. Haba, R. A. Boll, N. T. Brewer, S. V. Cleve, D. J. Dean, S. Ishizawa, Y. Ito, Y. Komori,K. Nishio, T. Niwase, B. C. Rasco, J. B. Roberto, K. Rykaczewski, H. Sakai, D. W. Stracener, and K. Hagino (oral), “Fusion dynamics
for hot fusion reactions revealed in quasielastic barrier distributions,” 6th International Conference on the Chemistry and Physics of theTransactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
M. Wada, P. Schury, H. Miyatake, Y. X. Watanabe, Y. Hirayama, H. Wollnik, S. Kimura, S. Ishizawa, T. Niwase, M. Rosenbusch, D. Kaji,
K. Morimoto, H. Haba, I. Takamine, T. Tanaka, H. Ishiyama, Y. Ito, J. Y. Moon, and K. Morita (invited), “SHE-Mass-II setup for direct
mass measurement of hot-fusion superheavy nuclides,” 6th International Conference on the Chemistry and Physics of the Transactinide
Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
Y. Ito, P. Schury, M. Wada, F. Arai, H. Haba, Y. Hirayama, S. Ishizawa, D. Kaji, S. Kimura, H. Koura, M. Maccormick, H. Miyatake,J. -Y. Moon, K. Morimoto, K. Morita, M. Mukai, I. Murray, T. Niwase, K. Okada, A. Ozawa, M. Rosenbusch, A. Takamine, T. Tanaka,
Y. Watanabe, H. Wollnik, and S. Yamaki (oral), “Direct mass measurements of mendelevium isotopes in the vicinity of the N =152 deformed shell-closure,” 6th International Conference on the Chemistry and Physics of the Transactinide Elements (TAN19),
Wilhelmshaven, Germany, August 25–30, 2019.
H. Haba (invited), “Present status and perspectives of superheavy element researches at RIKEN,” XXXVI’th Mazurian Lakes Conference
on Physics, Piaski, Poland, September 1–7, 2019.
H. Haba (invited), “RI production—Chemistry of new elements to diagnosis and treatment of cancer—,” Tsukuba Conference 2019,
Tsukuba, Japan, October 2–4, 2019.
Y. Kasamatsu, H. Ninomiya, S. Hayami, M. Nagase, E. Watanabe, Y. Shigekawa, N. Kondo, H. Haba, T. Yokokita, Y. Komori, D. Mori,Y. Wang, K. Ghosh, M. Kaneko, and A. Shinohara (poster), “Coprecipitation of nobelium with samarium hydroxide,” The 4th Interna-- 278 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

tional Symposium on Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
Z. Qin, Y. Wang, S. W. Cao, J. C. Zhang, F. L. Fang, J. Yang, H. Haba, Y. Komori, T. Yokokita, K. Morimoto, D. Kaji, Y. Wittwer,
R. Eichler, and A. Türler (invited), “Towards the bohrium carbonyl complexes in gas phase,” The 4th International Symposium on
Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
Y. Wang, Y. Wittwer, J. Zhang, S. Cao, Y. Komori, T. Yokokita, Y. Shigekawa, F. Fan, J. Yang, H. Haba, R. Eichler, A. Türler, and Z. Qin(oral), “Species identification of Re carbonyls using laser-ablation time-of-flight mass-spectrometer,” The 4th International Symposiumon Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
T. Yokokita, Y. Kasamatsu, E. Watanabe, Y. Komori, H. Ninomiya, Y. Wang, D. Mori, K. Ghosh, A. Shinohara, and H. Haba (oral),“Anion exchange of Rf, Zr, Hf, and Th in H2 SO4 ,” The 4th International Symposium on Superheavy Elements (SHE2019), Hakone,
Japan, December 1–5, 2019.
T. Niwase, M. Wada, P. Schury, Y. Ito, S. Kimura, D. Kaji, M. Rosenbusch, Y. X. Watanabe, Y. Hirayama, H. Miyatake, J. Y. Moon,
H. Ishiyama, K. Morimoto, H. Haba, T. Tanaka, S. Ishizawa, A. Takamine, K. Morita, and H. Wollnik (oral), “Correlation measurement of precision mass and decay properties of nuclei via MRTOF-MS with α-ToF detector,” The 4th International Symposium on
Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
M. Rosenbusch, M. Wada, P. Schury, S. Iimura, H. Haba, Y. Hirayama, H. Ishiyama, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Miyatake, J. Y. Moon, K. Morimoto, T. Tanaka, T. Niwase, A. Takamine, K. Morita, Y. X. Watanabe, and H. Wollnik (oral), “Dynamic
ejection-field correction for MR ToF mass spectrometry of SHE using arbitrary mass references,” The 4th International Symposium on
Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
H. Haba (plenary), “Production and applications of radioisotopes at RIKEN RI Beam Factory—Search for new elements through diagnosis
and therapy of cancer—,” The 10th International Conference on Isotopes (10ICI), Kuala Lumpur, Malaysia, February 3–7, 2020.
H. Haba (invited), “Present status and perspectives of superheavy element chemistry at RIKEN,” The 10th International Conference on
Isotopes (10ICI), Kuala Lumpur, Malaysia, February 3–7, 2020.

[Seminars]
H. Haba, “Production of radioisotopes for application Studies at RIKEN RI Beam Factory,” Seminar at Institute of Modern Physics (IMP),
Lanzhou, China, August 12, 2019.
H. Haba, “Production of radioisotopes for application Studies at RIKEN RI Beam Factory,” IFIN-HH Seminar at Horia Hulubei National
Institute for R&D in Physics and Nuclear Engineering, Bucharest, Rumania, October 21, 2019.
H. Haba, “Production of radioisotopes for application studies at RIKEN RI Beam Factory,” Seminar at Sunway University, Selangor,
Malaysia, February 10, 2020.

[Domestic conferences/workshops]Ӌ৔޺ޫʢট଴ߨԋʣ, ʮ৽‫ݩ‬ૉԽֶͷల๬ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑ଠ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. Moon, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ߴๆѪࢠ, ৿ాߒհ, H. Wollnikʢ‫ޱ‬಄ൃදʣ, ʮMRTOF-MS Λ༻͍ͨ 207 Ra ͷਫ਼ີ࣭ྔ–่յಛੑଌఆʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
ૣ઒༏ଠ, ࡔ‫ޱ‬ҁ, ଜాਅ༏, দଜՆ‫ل‬, ౻পमฏ, தౡ࿕‫ٱ‬, ּদྑਸ, ࣰ‫ްݪ‬, খ৿༗‫ࢠر‬, ԣ๺୎໵, ৿େً, ໼ೲ৻໵, Ӌ৔޺ޫ,ԣࢁ໌඙ʢ‫ޱ‬಄ൃදʣ, ʮU+p ‫ ͼٴ‬Th+Li ൓ԠʹΑΔ Np ಉҐମྭ‫਺ؔى‬ͷ࡞੒ʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ
͖, 2019 ೥ 9 ݄ 24–26 ೔.
ԣ๺୎໵, ּদྑਸ, ౉ᬒӯհ, খ৿༗‫ࢠر‬, ೋ‫ٶ‬लඒ, Ԧ༸, ৿େً, ΰʔγϡίʔελϒ, ࣰ‫ްݪ‬, Ӌ৔޺ޫʢ‫ޱ‬಄ൃදʣ, ʮེࢎ‫ܥ‬ʹ͓͚Δ Rf ͷӄΠΦϯަ‫׵‬ʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
଎ਫᠳ, ೋ‫ٶ‬लඒ, ౉ᬒӯհ, ॏՏ༏େ, Ӭ੉কߒ, ּদྑਸ, ۙ౻੒ඒ, Ӌ৔޺ޫ, ԣ๺୎໵, খ৿༗‫ࢠر‬, ৿େً, Ԧ༸, ΰʔγϡίʔελϒ, ࠤ౻๬, ࣰ‫ްݪ‬ʢ‫ޱ‬಄ൃදʣ, ʮਫࢎԽαϚϦ΢Ϝ‫ڞ‬௜๏Λ༻͍ͨ 102 ൪‫ݩ‬ૉϊʔϕϦ΢Ϝͷ௜఼࣮‫ݧ‬ʯ, ೔ຊ์ࣹԽֶձ
ୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. Moon, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ߴๆѪࢠ, ৿ాߒհ, H. Wollnikʢ‫ޱ‬಄ൃදʣ, ʮMRTOF + α-TOF Λ༻͍ͨ 207 Ra ͷ࣭ྔ–่յಛੑଌఆʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
҆ୡασΟΞ, ຤໦‫ܒ‬հ, ๛ౢް࢙, ௩ా࿨໌, Ӌ৔޺ޫ, খ৿༗‫ࢠر‬, ԣ๺୎໵, ৿େًʢϙελʔൃදʣ, ʮHF/HNO3 ਫ༹ӷதʹ
͓͚Δ Nb, Ta, Pa ͷӄΠΦϯަ‫ݧ࣮׵‬ʙDb ϑοԽ෺ࡨମͷਪఆʹ޲͚ͯʙʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖,2019 ೥ 9 ݄ 24–26 ೔.
৿ాྋխ, ૣ઒༏ଠ, খ৿༗‫ࢠر‬, ԣ๺୎໵, ৿େً, Ӌ৔޺ޫ, ּদྑਸ, ࣰ‫ްݪ‬, ԣࢁ໌඙ʢϙελʕൃදʣ, ʮ239 Np ෳ߹֩‫͓ʹܥ‬͚Δ֩෼྾அ໘ੵଌఆʹΑΔ‫ي‬ಓ֯ӡಈྔͷਪఆʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮ৽‫ݩ‬ૉΛ୳ͦ͏!ʯ, ೔ຊԽֶձ ‫ͪͨ܅‬ͷকདྷͱԽֶͷະདྷ ౦େͰա͢͝Խֶͳि຤, จ‫ژ‬, 2019 ೥ 10 ݄
20 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮ113 ൪χϗχ΢Ϝͷൃ‫ݟ‬ʯ, ࠃࡍप‫ظ‬ද೥ 2019 ಛผలΦʔϓχϯάΠϕϯτ, ࢁ‫ܗ‬, 2019 ೥ 11 ݄ 3 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮ‫ݩ‬ૉΛͭ͘Ζ͏ʂʯ, αΠΤϯεΞΰϥࠃࡍप‫ظ‬ද೥ಛผ‫ا‬ը ‫ݩ‬ૉ‫ݕ‬ఆ 2019@౦‫ژ‬, ߐ౦, 2019 ೥ 11 ݄
16 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮϥδΦΞΠιτʔϓͷ੡଄ͱԠ༻—৽‫ݩ‬ૉͷ୳ࡧ͔Β͕Μͷ਍அɾ࣏ྍ·Ͱ—ʯ, 2019 ೥౓೔ຊΞΠιτʔϓ‫ڠ‬ձγϯϙδ΢ϜʮPETɾΠϝʔδϯά‫ڀݚ‬ͷ࠷લઢʙϥΠϑαΠΤϯεͱཧ޻ֶͷ༥߹ʙʯ, ઒࡚, 2019 ೥ 11 ݄ 22 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮཧ‫͚͓ʹݚ‬ΔϥδΦΞΠιτʔϓͷ੡଄ͱԠ༻ʙ৽‫ݩ‬ૉͷ୳ࡧ͔Β͕Μͷ਍அɾ࣏ྍ·Ͱʙʯ, ୈ 75 ճ์ࣹઢ‫ܭ‬ଌ‫ڀݚ‬ձ, ࿨ޫࢢ, 2020 ೥ 1 ݄ 18 ೔.
খᖒ௚໵, ௕ᖛ߂‫ق‬, ૣਫ༑༸, தଜ‫ܓ‬༎, খߴ߁র, ాத߳௡ੜ, େ௩ະདྷ, খ৿༗‫ࢠر‬, ࢢ઒༤Ұ, Ӌ৔޺ޫ, ্໺लथ, ञ‫ݟ‬ହ‫׮‬ʢ‫ޱ‬- 279 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

಄ൃදʣ,ʮϑϥϯγ΢Ϝ‫ࢠݪ‬ͷి‫ؾ‬૒‫ࢠۃ‬ೳ཰୳ࡧͷͨΊͷද໘ి཭ΠΦϯ‫ݯ‬ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձʢ2020೥ʣ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. Moon, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ൧ଜढ़, ߴๆѪࢠ, ৿ాߒհ, H. Wollnikʢ‫ޱ‬಄ൃදʣ, ʮMRTOF+α-TOF Λ༻͍ͨ୹ण໋
α ่յ֩छͷ࣭ྔ–่յಛੑଌఆʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձʢ2020 ೥ʣ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Superheavy Element Research Group
Superheavy Element Device Development Team
1. Abstract
A gas-filled recoil ion separator has been used as a main experimental device for the study of superheavy elements. This team isin charge of maintaining, improving, developing, and operating the separators and related devices. In the RIBF facility, three gas-filled
recoil ion separators are installed at RILAC and RRC facility. One is GARIS that is designed for a symmetric reaction such as coldfusion reaction, and the other two are developed for an asymmetric reaction such as hot-fusion reaction, GARIS-II and GARIS-III.
New elements 278 113 were produced by 70 Zn + 209 Bi reaction using GARIS. Further the new element search Z > 118 is currently inprogress by using GARIS-II and GARIS-III.

2. Major Research Subjects(1) Maintenance of GARIS, GARIS-II and development of new separator GARIS-III(2) Maintenance and development of detector and DAQ system for superheavy element research(3) Maintenance and development of target system for GARIS, GARIS-II and GARIS-III

3. Summary of Research Activity
The GARIS-II and III are newly developed which has an acceptance twice as large as existing GARIS, in order to realize higher
transmission. A new element search program aiming to element 119 was started using GARIS-II. And new separator GARIS-III
was developed and installed into the RILAC experimental hall. It will be ready for operation in the physical year 2020 after somecommissioning works. We will also oﬀer user-support if a researcher wishes to use the devices for his/her own research program.

Members
Team Leader
Kouji MORIMOTO
Research/Technical Scientists
Masaki FUJIMAKI (concurrent: Senior Technical Scientist)

Daiya KAJI (Technical Scientist)

Postdoctoral Researchers
Pierre BRIONNET

Sota KIMURA

Junior Research Associates
Satoshi ISHIZAWA

Toshitaka NIWASE

Visiting Scientists
Shin-ichi GOTO (Niigata Univ.)
Eiji IDEGUCHI (Osaka Univ.)
Yuta ITO (JAEA)

Katsuhisa NISHIO (JAEA)
Fuyuki TOKANAI (Yamagata Univ.)

Student Trainees
Hayato NUMAKURA (Yamagata Univ.)
Yoshiki TAKAHASHI (Niigata Univ.)

Hiroki TSUNODA (Niigata Univ.)

List of Publications & Presentations
Publications[Original papers]
S. Ishizawa, K. Morimoto, D. Kaji, T. Tanaka, and F. Tokanai, “Improvement of the detection eﬃciency of a time-of-flight detector for
superheavy element search,” Nucl. Instrum. Methods Phys. Res. A 960, 163614 (2020).
T. Niwase, M. Wada, P. Schury, H. Haba, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Miyatake, K. Morimoto, K. Morita, M. Rosenbusch,
H. Wollnik, T. Shanley, and Y. Benari, “Development of an “α-TOF” detector for correlated measurement of atomic masses and decay
properties,” Nucl. Instrum. Methods Phys. Res. A, 953, 163198 (2020).
H. Numakura, K. Morimoto, D. Kaji, K. Kosugi, C. Horikawa, S. Ishizawa, M. Takeyama, and F. Tokanai, “Evaluation of a backilluminated solid state detector with thin dead layer for super heavy element research,” Jpn. J. Appl., Phys. 59, 066004 (2020).

[Review articles]ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. MOON, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ߴๆѪࢠ, ৿ాߒհ, H. Wollnik, ʮMRTOF+α-TOF Λ༻͍ͨ 207 Ra ͷ࣭ྔ-่յಛੑଌఆʯ,์ࣹԽֶ ୈ 41 ߸ 2020 ೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Presentations[International conferences/workshops]
K. Morimoto (invited), “The discovery of element 113,” TAN 19, Wilhelmshaven, Germany, August 2019.
S. Ishizawa (oral), K. Morimoto, D. Kaji, T. Tanaka, and F. Tokanai, “Improvement of the detection eﬃciency of a time-of-flight detector for superheavy element search,” The 2019 IEEE Nuclear Science Symposium (NSS) and Medical Imaging Conference (MIC),
Manchester, UK, October 26–November 5, 2019.
P. Brionnet (oral), “First measurement of the reaction 51 V+159 Tb → 210 Ra∗ on GARIS-II,” The 4th International Symposium on Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
T. Niwase (oral), M. Wada, P. Schury, Y. Ito, D. Kaji, M. Rosenbusch, Y. X. Watanabe, Y. Hirayama, J. Y. MOON, H. Ishiyama, T. Tanaka,
A. Takamine, S. Kimura, K. Morimoto, H. Haba, S. Ishizawa, K. Morita, H. Miyatake, and H. Wollnik, “Correlation measurement ofprecision mass and decay properties of nuclei via MRTOF-MS with α-ToF detector,” The 4th International Symposium on Superheavy
Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
S. Ishizawa (poster), K. Morimoto, D. Kaji, T. Tanaka, and F. Tokanai, “Improvement of the detection eﬃciency of a time-of-flight detector
with a large eﬀective area for superheavy element search,” The 4th International Symposium on Superheavy Elements (SHE2019),
Hakone, Japan, December 1–5, 2019.
T. Niwase (poster), M. Wada, P. Schury, Y. Ito, S. Kimura, D. Kaji, M. Rosenbusch, Y. X. Watanabe, Y. Hirayama, H. Miyatake,J. Y. Moon, H. Ishiyama, K. Morimoto, H. Haba, T. Tanaka, S. Ishizawa, A. Takamine, K. Morita, and H. Wollnik, “Development andfirst results from a novel “α-TOF” detector used with a multi-reflection time-of-flight mass spectrograph,” TAN 19, Wilhelmshaven,
Germany, August 2019.
H. Numakura (poster), C. Horikawa, K. Morimoto, S. Ishizawa, M. Takeyama, and F. Tokanai, “Evaluation of dead-layer thickness of
SSD for SHE research,” The 19th International Conference on Solid State Dosimetry (SSD19), Hiroshima, September 15–20, 2019.
I. Murakami (poster), S. Sakaguchi, D. Kaji, K. Morimoto, T. Niwase, K. Morita et al., “Development of MCP ToF Detectors at Kyushu
University,” The 4th International Symposium on Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
K. Morimoto (oral), “Discovery of Nh and search for element 119,” nSHE RG Collaboration Meeting. Oak Ridge National Laboratory
and the University of Tennessee Knoxville, US, May 30–June 1, 2019.
D. Kaji (oral), “GARIS-2/-3 performance,” nSHE RG Collaboration Meeting. Oak Ridge National Laboratory and the University ofTennessee Knoxville, US, May 30–June 1, 2019.
P. Brionnett (oral), “Data analysis I,” nSHE RG Collaboration Meeting. Oak Ridge National Laboratory and the University of Tennessee
Knoxville, US, May 30–June 1, 2019.
S. Ishizawa (oral), “Optimization of ToF system,” nSHE RG Collaboration Meeting. Oak Ridge National Laboratory and the Universityof Tennessee Knoxville, US, May 30–June 1, 2019.
S. Kimura (oral), “Determination of anchor via direct mass measurement with MR-TOF,” nSHE RG Collaboration Meeting. Oak Ridge
National Laboratory and the University of Tennessee Knoxville, US, May 30–June 1, 2019.
K. Morimoto (oral), “Present status and plans of GARIS, GARIS-II and GARIS-III,” SSRI-PNS Collaboration Meeting 2019, Nishina
hall, Nishina Bldg. 2F, September 4, 2019.

[Domestic conferences/workshops]ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. MOON, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ߴๆѪࢠ, ৿ాߒհ, H. Wollnik, ʮMRTOF-MS Λ༻͍ͨ 207 Ra ͷਫ਼ີ࣭ྔ-่յಛੑଌ
ఆʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. MOON, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ߴๆѪࢠ, ৿ాߒհ, H. Wollnik, ʮMRTOF+α-TOF Λ༻͍ͨ 207Ra ͷ࣭ྔ-่յಛੑଌ
ఆʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձ (2019), ͍Θ͖, 2019 ೥ 9 ݄.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. MOON, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ൧ଜढ़, ߴๆѪࢠ, ৿ాߒհ, H. Wollnik, ʮMRTOF+α-TOF Λ༻͍ͨ୹ण໋ α ่յ֩छͷ࣭ྔ-่յಛੑଌఆʯ, ೔ຊ෺ཧֶձ ୈ 75 ճ೥࣍େձ (2020 ೥), ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄.

Awardsఉ੉‫ོڿ‬, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձ (2019), एख༏लൃද৆ 2019 ೥ 9 ݄

Others৿ຊ޾࢘, ཧԽֶ‫ॴڀݚ‬ઋ୆஍۠ Ұൠެ։, ʮ৽‫ݩ‬ૉʮχϗχ΢Ϝʯͷൃ‫ͳͨ৽ͱݟ‬ల։ʯ, ཧԽֶ‫ ॴڀݚ‬ઋ୆஍۠, 2019 ೥ 07 ݄
27 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Astro-Glaciology Research Group
Summary of Research Activities

Our Astro-Glaciology Research Group promotes both experimental and theoretical studies to open up the new interdisciplinary
research field of astro-glaciology, which combines astrophysics, astrochemistry, glaciology, and climate science.
On the experimental side, we measure isotopic and ionic concentrations in ice cores drilled at Dome Fuji station, Antarctica,
in collaboration with the National Institute of Polar Research (NIPR, Tokyo). Here, the ice cores are time capsules which preserve
atmospheric information of the past. In particular, the ice cores obtained around the Dome Fuji site are very unique, because they
contain much more information on the stratosphere than any other ice cores obtained from elsewhere on Earth. This means that wehave significant advantages in using Dome Fuji ice cores if we wish to study the Universe, since UV photons, gamma-rays, and highenergy protons emitted by astronomical phenomena aﬀect the atmosphere of the stratosphere. Our principal aim is thus to acquire andinterpret information preserved in ice cores regarding:• Signatures of past volcanic eruptions and solar cycles;• Relationships between climate change and volcanic activity, and climate change and solar activity as well;• Traces of past supernovae in our galaxy, in order to understand better the rate of galactic supernova explosions.

Moreover, we are promoting experimental projects on:• Development of an automated laser melting sampler for analyzing ice cores with high depth resolution and high through-put;• Development of precise analytical techniques of high sensitivity for analyzing ice cores;• The application of analytical methods to measure isotopes developed for ice cores to archaeological artifacts;• The evolution of molecules in space.

On the theoretical side, we are simulating numerically:• Chemical eﬀects of giant solar flares and supernovae on the Earth’s atmosphere;• The explosive and the r-process nucleosynthesis in core-collapse supernovae.

Combining our experimental evidence and theoretical simulations, we are promoting the researches mentioned above. In particular,
climate change is the most critical issue facing the world in the 21st century. It is also emphasized that the frequency of supernova
explosions in our galaxy has not yet been fully understood, and this is a crucial key to understand of the r-process nucleosynthesis, oneof the goals of the Nishina Center. We note that our subjects all will contribute to an understanding relationships between the Universe
and Earth.

Members
Director
Yuko MOTIZUKI
Research/Technical Scientists
Kazuya TAKAHASHI (Senior Research Scientist)

Yoichi NAKAI (Senior Research Scientist)

Technical Staﬀ I
Yu Vin SAHOO
Senior Visiting Scientists
Yasushige YANO (RIKEN/Nishina Memorial Foundation)

Kunihiko KODERA (Meteorological Res. Inst.)

Visiting Scientists
Hideharu AKIYOSHI (Nat’l Inst. for Environmental Studies)
Akira HORI (Kitami Inst. of Tech.)
Kazuho HORIUCHI (Hirosaki Univ.)
Yoshinori IIZUKA (Hokkaido Univ.)

Naoyuki KURITA (Nagoya Univ.)
Hideki MADOKORO (Mitsubushi Heavy Industries, Ltd.)
Hideaki MOTOYAMA (Nat’l Inst. of Polar Res.)
Kenji TANABE (Okayama Univ. of Sci.)

Visiting Technician
Junya HIROSE (Fusion Tech. Co., Ltd.)
Student Trainee
Hisashi HAYAKAWA (Osaka Univ.)
Part-time Worker
Satomi NEGISHI (Part-time Worker I)- 283 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

List of Publications & Presentations
Publications[Original papers]
T. Minami, K. Hatanaka, Y. Motizuki, Y. Nakai, and K. Takahashi, “A method of collecting trace amounts of vermilion from artifacts
for source estimation by sulfur isotope (δ34S) analysis: use of sulfur-free adhesive,” Journal of Archaeological Science: Reports 28,
102027, (2019).

[Books]๬݄༏ࢠ,ʮNewton ϥΠτ 2.0 प‫ظ‬දʯ (‫)ྗڠ‬, χϡʔτϯϓϨε, 2019 ೥ 12 ݄.
๬݄༏ࢠ,ʮχϡʔτϯࣜ௒ਤղ ࠷‫ʹڧ‬໘ന͍!! प‫ظ‬දʯ (‫)ྗڠ‬, χϡʔτϯϓϨε, 2019 ೥ 7 ݄.

Presentations[International conferences/workshops]
Y. Motizuki (invited), “The oxygen isotopic variations in a Dome Fuji (Antarctica) ice core—Relationships of the temperature proxy withsolar activity and oceanic variations,” WCRP/SPARC SATIO-TCS joint workshop on Stratosphere-Troposphere Dynamical Couplingin the Tropics, Kyoto, February 21–25, 2020.
H. Akiyoshi, Y. Nakai, Y. Motizuki, T. Imamura, and Y. Yamashita, “Ozone change simulations of Halloween event and Carrington
event using MIROC3.2 chemistry-climate model,” WCRP/SPARC SATIO-TCS joint workshop on Stratosphere-Troposphere Dynamical Coupling in the Tropics, Kyoto, February 21–25, 2020.
Y. V. Sahoo, K. Takahashi, Y. Nakai, Y. Motizuki, and H. Motoyama, “Annually-resolved water isotope measurements in a shallow ice
core (DFS10) for 60 meters depth,” (A poster paper), The Tenth Symposium on Polar Science, Tachikawa, December 3–5, 2019.
S. Fujita, K. Goto-Azuma, M. Hirabayashi, A. Hori, Y. Iizuka, Y. Motizuki, H. Motoyama, K. Takahashi, H. Enomoto, K. Fukui,
Y. Hoshina, F. Nakazawa, S. Sugiyama, and S. Surdylk, “Metamorphism of layered firn at Dome Fuji, Antarctica: Evolution of relations
between Near-infrared reflectivity and the other textural/chemical properties,” The Tenth Symposium on Polar Science, Tachikawa, December 3–5, 2019.
K. Kanzawa, F. Miyake, Y. Tada, K. Horiuchi, S. Otani, K. Sasa, Y. Motizuki, K. Takahashi, Y. Nakai, H. Motoyama, and H. Matsuzaki,“Variation of cosmogenic 10Be for cosmic ray event in 5480 BC from Antarctic Dome Fuji ice core,” The 8th East Asia Accelerator
Mass Spectrometry Symposium, Nagoya, Japan, December 3–6, 2019.
Y. Motizuki (invited), “Women in Astronomy: A view from a gender-imbalanced country,” IAU Symposium 358: “Astronomy for Equity,
Diversity and Inclusion—a roadmap to action within the framework of IAU centennial anniversary,” Tokyo, November 12–15, 2019.
Y. Motizuki (invited), “Historical supernova signatures in polar ice cores,” International workshop on “Historical supernovae, novae andother transient events,” Leiden, the Netherlands, October 14–18, 2019.

[Domestic conferences/workshops]
๬݄༏ࢠ, ߴ‫ڮ‬࿨໵, தҪཅҰ, Y. V. Sahoo, ຊࢁल໌, খࣉ๜඙, ʮೆ‫ۃ‬υʔϜ;͡ΞΠείΞ͔Β͙͞Δ‫ؾ‬Թมಈͱଠཅ‫׆‬ಈͱͷ૬ؔʯ, ೔ຊఱจֶձ 2020 ೥य़‫ق‬೥ձ, ͭ͘͹, 2020 ೥ 3 ݄ 16–19 ೔.
தҪཅҰ, ೔ߴ޺, ౉ล௚थ, ʮ௿ΤωϧΪʔΠΦϯͱ௿Թණද໘ͱͷ൓Ԡ࣮‫૷ݧ‬ஔ։ൃͷ‫ݱ‬ঢ়ʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ,໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16 ೔–19 ೔.
ੁᖒՂੈ, ࡾ୐ෙࠫ, ଟా༔അ, ງ಺Ұึ, େ୩Ꮺ, ࡫ެ࿨, ߴ‫౒ڮ‬, দଜਅणඒ, མ߹༔ଠ, ๬݄༏ࢠ, ߴ‫ڮ‬࿨໵, தҪཅҰ, ຊࢁल໌,দ࡚ߒ೭, ʮBC5480 ೥Ӊ஦ઢΠϕϯτʹ͓͚ΔυʔϜ;͡ΞΠείΞதͷ 10Be ͱ 36Cl ೱ౓ͷมಈʯ, ୈ 67 ճԠ༻෺ཧֶձय़
‫ֶق‬ज़ߨԋձ, ౦‫ژ‬, 2020 ೥ 3 ݄ 12–15 ೔.
ࡾ୐ෙࠫ, ງ಺Ұึ, ᓎҪ‫ٱܟ‬, ๬݄༏ࢠ, தҪཅҰ, ߴ‫ڮ‬࿨໵, ຊࢁल໌, দ࡚ߒ೭, ʮӉ஦ઢੜ੒֩छΛ༻͍ͨ‫ݩل‬લ 660 ೥ࠒͷӉ஦ઢΠϕϯτௐࠪʯ, ୈ 67 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, ౦‫ژ‬, 2020 ೥ 3 ݄ 12–15 ೔.
๬݄༏ࢠ (ট଴ߨԋ), ʮೆ‫ۃ‬ණதͷ֩छଘࡏൺ͔Βա‫ڈ‬ͷ‫ީؾ‬มಈΛ͙͞Δ—Ӊ஦ͱͷؔ࿈Λࢹ໺ʹʯ, ࡛‫ۄ‬େֶཧֶ෦෺ཧྔࢠ
ྗֶಛผߨٛ, ͍ͨ͞·, 2020 ೥ 1 ݄ 20 ೔.
ߴ‫ڮ‬࿨໵ (ট଴ߨԋ), ʮ‫ۃ‬ඍྔͷེԫಉҐମൺ෼ੳʹΑΔ, Ҩ੻͔Βग़౔ͨ͠ਫۜगͷ࢈஍ಉఆʯ, ୈ 370 ճΨεΫϩϚτάϥϑΟʔ‫ڀݚ‬ձಛผߨԋձ, ʮՊֶͱจԽʹߩ‫͢ݙ‬ΔΨεΫϩϚτάϥϑΟʔ—ਓΛ஌Δ, ஍‫ٿ‬Λ஌Δ, Ӊ஦Λ஌Δʯ, ౦‫ژ‬, 2019 ೥ 11 ݄
22 ೔.
๬݄༏ࢠ (ট଴ߨԋ), ʮυʔϜ;͡ΞΠείΞ͔Β୳Δ‫ީؾ‬มಈͱଠཅ‫׆‬ಈͱͷؔ܎ʯ, ౦‫ژ‬େֶେֶӃཧֶ‫ڀݚܥ‬Պ ஍‫ٿ‬࿭੕Պֶઐ߈ ࠤ౻‫ࣨڀݚ‬ηϛφʔ, ౦‫ژ‬, 2019 ೥ 10 ݄ 8 ೔.
ੁᖒՂੈ, ࡾ୐ෙࠫ, ଟా༔അ, ງ಺Ұึ, େ୩Ꮺ, ࡫ެ࿨, ๬݄༏ࢠ, ߴ‫ڮ‬࿨໵, தҪཅҰ, ຊࢁल໌, দ࡚ߒ೭, ʮυʔϜ;͡ΞΠείΞத 10Be ͱ 36Cl ೱ౓ͷଌఆʹΑΔ BC5480 ೥Ӊ஦ઢΠϕϯτͷௐࠪʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄
17–20 ೔.
தҪ ཅҰ, ೔ߴ޺, ౉෦௚थ, ʮ੕ؒਖද໘Λ໛ٖͨ͠௿Թණද໘ͱ௿ΤωϧΪʔΠΦϯͱͷ൓Ԡ࣮‫૷ݧ‬ஔͷ։ൃʯ(ϙελʔൃද),‫ࢠݪ‬িಥֶձୈ 44 ճ೥ձ, ௐ෍, 2019 ೥ 9 ݄ 5 ೔.
๬݄༏ࢠ (ট଴ߨԋ), ʮೆ‫ۃ‬ͷණ͔Βͻ΋ͱ͘Ӊ஦ͱ஍‫ٿ‬ͷྺ࢙ʯ, ެӹࡒஂ๏ਓࢁా௕ຬ঑ֶձ 30 प೥‫ه‬೦ߨԋձ, ઒࡚, 2019 ೥
7 ݄ 20 ೔.

Press releasesߴ‫ڮ‬࿨໵, ๬݄༏ࢠ, ೆ෢ࢤ, ʮ௒ඍྔེԫಉҐମൺ෼ੳΛߟ‫ʹֶݹ‬Ԡ༻͢Δ—‫ాژ‬Ҩ੻ͷग़౔඼͔Β੺৭‫إ‬ྉΛਫ਼ີ෼ੳ—ʯ, 2019೥ 11 ݄ 26 ೔. https://www.riken.jp/press/2019/20191126_2/- 284 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

K. Takahashi and Y. Motizuki, “Sticky tape: A key ingredient for mapping artifact origins,” March 9, 2020. https://www.riken.jp/
en/news_pubs/research_news/pr/2019/20191126_2/
RIKEN Science News blog; It Ain’t Magic, “Tape and vermilion: ingredients for mapping artifact origins,” by Adam Phillips, March 9,2020. https://itaintmagic.riken.jp/hot-off-the-press/tape-and-vermilion-ingredients-for-mappingartifact-origins/๬݄༏ࢠ (‫ݸ‬ผऔࡐड), ʮαΠΤϯε View: ஍‫ݹ࠷ٿ‬ͷණ ۷࡟ͤΑʯಡച৽ฉ‫ࣄه‬, 2019 ೥ 5 ݄ 26 ೔.

Outreach activities๬݄༏ࢠ (ট଴ߨԋ), ʮೆ‫ۃ‬ͷණ͔Βͻ΋ͱ͘Ӊ஦ͱ஍‫ٿ‬ͷྺ࢙ͱ‫ڥ؀ڀݚ‬ΛօͰ੔͍͑ͯ͘͜ͱͷେ੾͞ʯ, ߴদୈҰߴ౳ֶߍ(߳઒‫ )ݝ‬ཧ‫ஂݚ‬ମ‫ֶݟ‬, ࿨ޫ, 2019 ೥ 7 ݄ 29 ೔.
Y. V. Sahoo (Invited talk), “Studying and pursuing research positions in Japan,” Sakura Science High School Program promoted by
Department of Japan-Asia Youth Exchange Program in Science, Japan Society and Technology Agency, Wako, June 11, 2019.
๬݄༏ࢠ (ট଴ߨԋ), ʮೆ‫ۃ‬ͷණ͔Βͻ΋ͱ͘Ӊ஦ͱ஍‫ٿ‬ͷྺ࢙ʯ, KEK-TYL εΫʔϧཧ‫ࢠঁܥ‬Ωϟϯϓ 2019, ͭ͘͹, 2019 ೥ 4
݄ 3–4 ೔.

OthersK. Takahashi, “Detecting traces of sulfur in ice cores—An advanced isotope-measuring system can reveal insights about past environments
in shorter time,” RIKEN RESEARCH, SUMMER 2019, November 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Nuclear Transmutation Data Research Group
1. Abstract

The nuclear waste problem is an inevitable subject in nuclear physics and nuclear engineering communities. Since the Chicago
Pile was established in 1942, nuclear energy has become one of major sources of energy. However, nowadays the nuclear waste
produced at nuclear power plants has caused social problems. Minor actinide components of the waste have been studied well as a fuelin fast breeder reactors or ADS. Long-lived fission products (LLFP) in waste, on the other hand, have not been studied extensively. A
deep geological disposal has been a policy of several governments, but it is diﬃcult to find out location of the disposal station in termsof security, sociology and politics. To solve the social problem, a scientific eﬀort is necessary for nuclear physics community to findout eﬃcient methods for reduction of nuclear waste radioactivity. In the world-wide situation above, our Group aims to obtain reaction
data of LLFP at RIBF and other muon facilities for muon capture data. These data are necessary to design an accelerator-based system
for transmutation, and also may lead to a new discovery and invention for peaceful use of nuclear power and the welfare of humanity.

2. Major Research Subjects

The Group is formed by three research teams. The first two Teams, “Fast RI Data Team” and “Slow RI Data Team,” are in
charge of proton- and deuteron-induced reaction data of LLFP in inverse kinematics at RIBF. The third Team “Muon Data Team” isto obtain muon capture data of LLFP at muon facilities. All of the teams are focusing to obtain high-quality data which are essentiallynecessary to establish reliable reaction models. Each team has its own subjects and promotes LLFP reaction programs based on theirlarge experiences, techniques and skills.

3. Summary of Research Activity

In 2014, all the teams polished up experimental strategies, formed collaboration and prepared experiments. Physics runs forspallation reaction were successfully organized at RIBF in 2015–2017. The muon program started at RCNP, Osaka University inspring 2016 and the data for Pd isotopes were successfully obtained in 2017–2019 via in-beam method with DC beams at RCNP, andvia activation method with pulsed beams at J-PARC and ISIS-RAL/RIKEN facilities.
The reaction data obtained with both fast and energy-degraded beams at RIBF encouraged the nuclear data group of JAEA, anda new database called “JENDLE/ImPACT-2018” has been released. The new database has been generated by a newly developed
reaction model “DEURACS” which treats deuteron-induced reactions. DEURACS reproduces very well cross section data, and muchbetter than other reaction models. A simulation code “PHITS” has been re-coordianted to use the database information.
In December 2018, the Team leader, Hideaki Otsu, was invited to join Technical Meeting of IAEA, entitled “Novel Multidisciplinary Applications with Unstable Ion Beams and Complementary Techniques.” Our activity has been demonstrated and recognizedinternationally.

MemberGroup Director
Hiroyoshi SAKURAI (concurrent: Director, RI Physics Lab.)

List of Publications & Presentations
Publications[Original papers]
H. Okuno, H. Sakurai, Y. Mori, R. Fujita, and M. Kawashima, Proceedings of the Japan Academy, Series B 95, 430–439 (2019).

Presentations[International conferences/workshops]
H. Sakurai (invited), “A program for accelerator-based transmutation system for LLFP,” Fourth International Workshop on Technology
and Components of Accelerator-Driven Systems (TCADS-4), Antwerp, Belgium, October 14–17, 2019.

Press releasesʮʮ֩ͷΰϛʯ໰୊ղܾʹඞཁͳՃ଎‫ث‬ͷ֓೦ΛఏҊ—‫ط‬ଘͷ 300 ഒͷߴग़ྗॏཅࢠϏʔϜͷՃ଎͕Մೳʹ—ʯ, 2019 ೥ 8 ݄ 9 ೔.

Patents
Outreach activitiesᓎҪതّ, ʮʮ֩ͷΰϛʯΛΊ͙Δ‫ݩ‬ૉม‫΁׵‬ͷ௅ઓʯ, ࡾୋωοτϫʔΫେֶ, 2019 ೥ 9 ݄ 19 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Nuclear Transmutation Data Research Group
Fast RI Data Team
1. Abstract

Fast RI team aims at obtaining and accumulating the cross section data for long lived fission products (LLFPs) in order to explore
the possibility of using accelerator for nuclear transmutation.
LLFPs as nuclear waste have been generated continuously in nuclear power plants for wealth for human lives, while people
noticed the way of disposal has not necessarily been established, especially after the Fukushima Daiichi power plant disaster. One of
the ways to reduce the amount of LLFP or to recover them as recycled resources is nuclear transmutation technique.
RIBF facility has a property to generate such LLFP as a secondary beam and the beam species are identified by event by event.
Utilizing the property, absolute values of the cross section of various reactions on LLFPs are measured and accumulated as a database.

2. Major Research Subjects(1) Measurement of reaction products by the interaction of LLFPs with proton, deuteron, and photon to explore candidate reactions for the transmutation of LLFPs.
(2) Evaluation of the cross section data for the neutron induced reactions from the obtained data.

3. Summary of Research Activity
(1)
(2)
(3)
(4)

Acting as a collaboration hub on many groups which plan to take data using fast RI beams in RIBF facility.
Concentrating on taking data for proton and deuteron induced spallation reactions with inverse kinematics.
Accumulating the cross section data and evaluating them as evaluated nuclear data.
Evaluating cross section of neutron induced reaction on LLFP by collaborating with the nuclear model calculation and evaluation group.

Members
Team Leader
Hideaki OTSU (Concurrent: Team Leader, SAMURAI Team)
Visiting Scientists
Takashi TERANISHI (Kyushu Univ.)
Student Trainees
Keita NAKANO (Kyushu Univ.)

List of Publications & Presentations
Publications[Original papers]
H. Wang, H. Otsu, N. Chiga et al., “Enhancement of element production by incomplete fusion reaction with weakly bound deuteron,”Commun. Phys. 2, 78 (2019).
K. Nakano, Y. Watanabe, S. Kawase, H. Otsu et al., “Isotope production in proton-, deuteron-, and carbon-induced reactions on 93 Nb at
113 MeV/nucleon,” Phys. Rev. C 100, 044605 (2019).
S. Michimasa, J. Hwang, K. Yamada, H. Otsu et al., “OEDO, the energy-degrading beamline at RI Beam Factory,” Prog. Theor. Exp.
Phys. 4, 043D01 (2019).
J. Hwang, S. Michimasa, S. Ota, H. Otsu et al., “Angle-tunable wedge degrader for an energy-degrading RI beamline,” Prog. Theor. Exp.
Phys. 4, 043D02 (2019).
S. Takeuchi, T. Nakamura, M. Shikata, H. Otsu et al., “Coulomb breakup reactions of 93, 94 Zr in inverse kinematics,” Prog. Theor. Exp.
Phys. 1, 013D02 (2019).

[Proceedings]
X. Sun, H. Wang, H. Otsu, H. Sakurai et al., “Cross section measurements in the reactions of 136 Xe on proton, deuteron and carbon
at 168 MeV/u,” Proc. of the 15th Internat. Conf. on Nuclear Reaction Mechanisms, CERN-Proceedings-2019-001 (CERN, Geneva,2019), pp. 153–157.
Yu. Watanabe, J. Suwa, K. Nakano, H. Otsu et al., “Isotopic production cross sections of residual nuclei in proton- and deuteron-induced
reactions on 91, 92 Y, 92, 93 Zr, and 93, 94 Nb around 100 MeV/nucleon,” Proc. of the 15th Internat. Conf. on Nuclear Reaction Mechanisms,
CERN-Proceedings-2019-001 (CERN, Geneva, 2019), pp. 139–144.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Presentations[International conferences/workshops]
H. Otsu, “Cross section measurements for LLFP nuclei at RIBF,” Fourth International Workshop on Technology and Components ofAccelerator-Driven Systems (TCADS-4), Antwerp, Belgium, October 14–16, 2019.
H. Wang, “Spallation reaction study for long-lived fission products in nuclear waste,” International Nuclear Physics Conference 2019
(INPC2019), Glasgow, UK, July 29–August 2, 2019.
H. Wang, “Spallation reaction study for long-lived fission products in nuclear waste,” International conference on nuclear data andtechnology (ND2019), Beijing, China, May 19–24, 2019.
K. Nakano, “Isotope-production Cross Sections of Residual Nuclei in Proton- and Deuteron-induced Reactions on 93 Zr at 50 MeV/u,”International conference on nuclear data and technology (ND2019), Beijing, China, May 19–24, 2019.
X. Sun, “Cross-section Measurement in the Reactions of 136 Xe on Proton, Deuteron and Carbon,” International conference on nuclear
data and technology (ND2019), Beijing, China, May 19–24, 2019
Y. Togano et al., “Status report of dipole strength measurement performed in S09 and ImPACT,” SAMURAI International Collaboration
Workshop, Rikkyo University, Japan, August 30–31, 2019.

[Domestic conferences/workshops]େ௡ल‫ ڿ‬ଞ 4 ໊, ImPACT-RIBF Collaboration, ʮ֩ม‫ʹ׵‬ΑΔߴϨϕϧ์ࣹੑഇ‫غ‬෺ͷେ෯ͳ௿‫ݮ‬ɾࢿ‫ݯ‬Խ (4-1), “LLFP ͷஅ໘ੵଌఆͱͦͷΤωϧΪʔґଘੑ”ʯ, ೔ຊ‫ֶྗࢠݪ‬ձ, ਫ‫ށ‬, 2019 ೥ 3 ݄.

Press releasesϫϯɾϔ (Wang He), େ௡ल‫ڿ‬, ᓎҪതّ, ʮॏཅࢠʹΑΔ‫ݩ‬ૉม‫཰֬׵‬ͷ૿େ—ͦͷ··༥߹͢Δ͔, ෼྾͔ͯ͠ΒҰ෦͚ͩ༥߹
͢Δ͔—ʯ, ཧԽֶ‫ॴڀݚ‬, 2019 ೥ 7 ݄ 5 ೔.

Doctor thesesத໺‫ܟ‬ଠ, “Study of Isotope Production in Proton- and Deuteron-Induced Spallation Reactions on 93 Nb and 93 Zr,” ‫۝‬भେֶ େֶӃ૯߹ཧ޻ֶ෎.

Bachelor thesesদଜཧ‫ٱ‬, ʮ֩෼྾ੜ੒֩छ 90 Sr ͷཅࢠ͓Αͼॏཅࢠ༠‫ى‬൓Ԡʹؔ͢Δ‫ڀݚ‬ʯ, ౦๜େֶ ཧֶ෦.
੢௡ඒ࡙, ʮSe-79 ͷ֩ഁࡅ൓Ԡσʔλऔಘʹ޲͚ͨೋ࣍ϏʔϜͷཻࢠࣝผʯ, ‫۝‬भେֶ ૯߹ཧ޻ֶ෦.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Nuclear Transmutation Data Research Group
Slow RI Data Team
1. Abstract

This team is in charge of the development of low-energy RI beams of long-lived fission fragments (LLFP) from the 238 U by meansof degrading the energy of beams produced by the BigRIPS fragment separator.

2. Major Research Subjects
Studies of the slowing down and purification of RI beams are the main subjects of the team. Developments of devices used forthe slowing down of RI beams are also an important subject.
(1) Study and development of the slowed-down methods for LLFP.
(2) Development of the devices used for the slowing down.
(3) Operation of the BigRIPS separator and supply the low energy LLFP beam to the experiment in which the cross sections of
LLFP are measured at the low energy.
(4) Development of the framework to seamlessly handle device, detector, DAQ, and analysis for the easy control of the complicate
slowed-down RI beam production and its development.

3. Summary of Research Activity
A new OEDO beam line, designed for the slowed-down RI beams, was constructed under the collaboration with CNS, the University of Tokyo. Our group was responsible for the construction of the infrastructure such as the cooling water and the electricalequipment, and the movement and alignment of existing vacuum chambers, quadrupole magnets. The power supply for the Superconducting Triplet Quadrupoles (STQ) was made, which had a stability also under the low current condition.
Slowed-down 93 Zr beams with 20 or 50 MeV/nucleon were successfully developed at June 2016 for the first time. The methods
to obtain the narrow energy, position, and angle distribution were developed. The methods of the energy adjustment and the particle
identification at 50 MeV/nucleon were developed. The 93 Zr and 107 Pd beams with 50 MeV/nucleon were produced for the nucleartransmutation experiments using proton or deuteron targets at October 2016. The commissioning experiment of the OEDO beam line
was successfully performed at June 2017. The first transmutation experiments using OEDO beam line were performed with 93 Zr,
107
Pd, and 79 Se around 20 MeV/nucleon.
With our developments, the slowed-down RI beams became ready for the transmutation experiments. On the other hand, theprocedure to make the slowed-down RI beams became highly specialized. In order to easily produce the slowed-down RI beam, theframework is under the development to seamlessly handle the device, detector, DAQ, and analysis.

Members
Team Leader
Toshiyuki SUMIKAMA
Student Trainee
SungHan BAE (Seoul Nat’l Univ.)

List of Publications & Presentations
Publications[Original papers]
S. Takeuchi et al., “Coulomb breakup reactions of 93, 94 Zr in inverse kinematics,” Prog. Theor. Exp. Phys. 2019, 013D02 (2019).
S. Michimasa et al., “OEDO, the energy degrading beamline at RI Beam Factory,” Prog. Theor. Exp. Phys. 2019, 043D01 (2019).
H. Jongwon et al., “Angle-tunable wedge degrader for an energy-degrading RI beamline,” Prog. Theor. Exp. Phys. 2019, 043D02 (2019).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
Nuclear Transmutation Data Research Group
Muon Data Team
1. Abstract

Dr. Yoshio Nishina observed muons in cosmic rays in 1937. The muon is an elementary particle similar to electron and classified
to lepton group. The muon has positive or negative electric charge, and the lifetime is 2.2 µsec. The negative muon (µ− ) is 207 times
heavier than the electron and behaves as a “heavy electron” in materials. The negative muon is captured by atomic orbits of nuclei toform a muonic atom and cascades down to the 1 s orbit to make muon nuclear capture. The muon is combined with a proton in the
nucleus to convert to a neutron and a neutrino. The muon nuclear capture reaction on a nucleus (ZA N) with the atomic number Z andmass number A generates the isotopes of ZA––1x N (x = 0, 1, 2, 3, 4) by emitting some neutrons in the reaction. The phenomenon is called“muon nuclear transmutation.” The reaction branching ratio of ZA N(µ− , xnν)ZA––1x N reactions (x = 0, 1, 2, 3, 4) is one of importantfactors toward various applications with nuclear transmutation technique. From a viewpoint of the nuclear physic, the muon nuclear
capture reaction is very unique and interesting. A high-energy compound nuclear state is suddenly generated in the nuclei associatedwith a weak conversion process of proton to neutron and neutrino. Many experimental results have been so far reported, however, thereaction mechanism itself is not well clarified. The research team aims at obtaining the experimental data to investigate the reaction
mechanism of muon nuclear capture, and also at theoretical understanding on the nuclear capture reaction.

2. Major Research Subjects(1) Experimental clarification on the mechanism of nuclear muon capture reaction(2) Theoretical understanding on the nuclear muon capture reaction(3) Interdisciplinary applications with the nuclear transmutation technique

3. Summary of Research Activity

There are two experimental methods to study the muon nuclear capture reaction. The first one is “muon in-beam spectroscopy
method.” The neutron and γ-ray emissions from the excited states of ZA––1x N nuclei are prompt events and are observed by the “muonin-beam spectroscopy method” with a DC muon beam. The reaction branching ratio is directly determined by measuring the neutron
multiplicity in the reaction. The DC muon beam is available at the MuSIC (Muon Science Innovative Channel) muon facility in the
Research Center for Nuclear Physics (RCNP) at Osaka University. The second one is “muon activation method” with the pulsed
muon beam. The produced unstable nuclei ZA––1x N make β+/− decays. The γ-rays associated with β+/− decays to the daughter nuclei areobserved in the experiment. The build-up curve of γ-ray yield at muon beam-on and the decay curve at beam-oﬀ are measured. Since
the half-lives and decay branching ratios of β+/− -γ decays are known, the reaction branching ratios to the ZA––1x N nuclei are determinedby the γ-ray yield curves. The pulsed muon beam is available at the RIKEN-RAL Muon Facility in the UK and J-PARC muon facility.
Muon nuclear capture reactions are studied on five isotope-enriched palladium targets (104, 105, 106, 108, 110 Pd) and five isotopeenriched zirconium targets (90, 91, 92, 94, 96 Zr) employing two experimental methods. By obtaining the experimental data on the Pd and Zr
targets, the reaction mechanism is investigated experimentally, and the results are compared with appropriate theoretical calculations.
The 107 Pd is classified to a long-lived fission product (LLFP) and is contained in a spent nuclear fuel. The study of muon nuclear
capture on the Pd and Zr targets is aiming at exploring a possible reaction path to make the nuclear transmutation of the Pd and Zr
metal extracted from the spent nuclear fuel without an isotope separation process. This research was funded by the ImPACT Programof Council for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
(1) Experiments with “muon in-beam spectroscopy method”
Muon nuclear capture reactions were investigated on five palladium targets (104, 105, 106, 108, 110 Pd) by employing the DC muon
beam at MuSIC. The γ-ray and neutron in the muon nuclear capture reaction were measured with the time information relative toA
A– xPd(µ− , xnν)45
Rh reactions, wheremuon beam arrival. The measured neutron multiplicity gives the reaction branching ratio of 46
A = 104, 105, 106, 108, 110 and x = 0, 1, 2, 3, 4.
Employing a newly built neutron spectrometer, the neutron was measured to obtain the reaction branching ratios of muon capture
reactions on the Pd targets. We have constructed a neutron spectrometer named “Seamine”: Scintillator Enclosure Array for Muon
Induced Neutron Emission. The spectrometer consists of 21 liquid scintillation counters, 2 Ge γ-ray detectors, 7 BaF2 counters. The
Pd target, muon beam counters and muon degraders are placed at the center of spectrometer. The neutron counter is a BC-501A
liquid scintillation counter with 20 cm diameter and 5 cm depth and is connected to a 5” photo multiplication tube (H4144-01). The
total neuron detection eﬃciency is estimated 5%, where the distance is 4 cm from the target to neutron counters. The Ge γ-ray
detectors are placed at 10 cm form the target, and the typical detection eﬃciency is 0.5% for 200 keV γ-ray. The BaF2 counters arelocated beneath the target to detect fast γ-rays emitted from the compound nucleus formed in the reactions. Signals from the liquid
scintillation counters are processed in a CAEN V1730B waveform digitizer (16 channel, 14 bit, 500 M samplings/sec.). The neuron-γ
discrimination is performed on-line during the experiment, and the detailed data analysis is conducted oﬀ-line after the experiment.
The neutron energy spectrum is constructed in the digitizer. Signals from Ge detectors are also processed in the digitizer to obtain theenergy and time spectrum of γ-rays associated with the reaction. Signals from the BaF2 counters and muon beam counters are sent to
the digitizer to make the fast timing signals.
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is in progress to obtain the multiplicity, the energy and the TOF spectrum using start signals given by γ-rays detected in the BaF2
counters. The γ-ray data gives the energy spectrum of prompt γ-rays and muonic X-rays originated from the 104, 105, 106, 108, 110 Pdtargets.
(2) Experiments with “muon activation method” at the RIKEN-RAL Muon Facility
We conducted the experiments on the muon nuclear capture employing the muon activation method at the RIKEN-RAL Muon
Facility in the UK. The pulsed muon beam was irradiated on the 104, 105, 106, 108, 110 Pd targets. The γ-rays were detected by a Ge detector
located at the downstream of the Pd targets to maximize the detection eﬃciency. The build-up and decay curves of γ-ray intensities
were measured associated with β+/− decays of produced unstable nuclei to daughter nuclei. The γ-ray-yield curves give the absoluteAA– xPd(µ− , xnν)45
Rh reactions. The
radiation activity produced by the reaction, and the reaction branching ratios are determined for 46
decay curves of γ-rays from the produced nuclei with long half-lives were measured under low γ-ray background at an experimental
apparatus built in a separated room. The detailed oﬀ-line data analysis is in progress.
(3) Experiments with “muon activation method” at J-PARC muon facility
The experiments employing the muon activation method were performed at J-PARC muon facility. The five isotope-enriched Pdtargets (104, 105, 106, 108, 110 Pd) were irradiated by the pulsed muon beam, and the build-up and decay curves of γ-ray intensities were
measured.
In addition to the Pd targets, the experiments on five isotope-enriched Zr target (90, 91, 92, 94, 96 Zr) were conducted to obtain theA
A– xZr(µ− , xnν)39
Y reactions, where A = 90, 91, 92, 94, 96. The obtained reaction branching ratios on thereaction branching ratios of 40
Pd and Zr targets are important to understand the reaction mechanism of muon nuclear capture. The 93 Zr is one of the LLFP and iscontained in a spent nuclear fuel. The experiment on the Zr targets is to explore a possibility to realize the nuclear transmutation of
the Zr metal extracted from the spent nuclear fuel.
−107– xIn order to obtain the reaction branching ratio of 107
46 Pd(µ , xnν)45 Rh reactions, the muon activation experiment was performed
employing a Pd target containing 107 Pd of 15.3%. The γ-ray intensities associated with β+/− decays of produced unstable nuclei were
measured to obtain the build-up and decay curves. Once the branching ratios of the reactions on the 104, 105, 106, 108, 110 Pd targets are
obtained, these contributions are extracted from the branching-ratio data obtained for the Pd target with 107 Pd. The reaction branching−
107– xratio of 107
46 Pd(µ , xnν)45 Rh reactions is finally determined. The detailed oﬀ-line data analysis is in progress.
(4) Comparison with theory
The muon activation method gives the reaction branching ratios. The muon in-beam spectroscopy method gives the neutron
multiplicity and the neutron energy spectrum. These experimental results are important to understand the compound nuclear state andneutron emission mechanism. The reaction branching ratios obtained by the muon activation method are compared with the results ofneutron multiplicity measurements. The neutron energy spectrum is considered to be reflected by the energy distribution of compound
nuclear state and neutron emission mechanism. The experimental results are compared with the appropriate calculations employing theneutron emission mechanisms due to an evaporation, a cascade and a direct emission processes with assuming the energy distribution
at compound nuclear state.

Members
Team Leader
Hiroyoshi SAKURAI
Contract Researcher
Teiichiro MATSUZAKI

List of Publications & Presentations
Publications[Original papers]
S. Wenner, C. D. Marioara, K. Nishimura, K. Matsuda, S. Lee, T. Namiki, I. Watanabe, T. Matsuzaki, and R. Holmestad, “Muon spin
relaxation study of solute?vacancy interactions during natural aging of Al-Mg-Si-Cu alloys,” Metall. Mater. Trans. A 50, 3446–3451(2019).

[Proceedings]
R. Fujita, M. Kawashima, M. Ozawa, and T. Matsuzaki, “Reduction and resource recycling of high-level radioactive wastes throughnuclear transmutation—overview and current progress—,” Proceeding for the 13th International Conference on Nucleus-Nucleus Collisions (NN2018).

Presentations[International conferences/workshops]
T. Saito, M. Niikura, T. Matsuzaki, and H. Sakurai for ImPACT muon collaboration, “Neutron emission property after nuclear muon
capture of palladium,” International Nuclear Physics Conference 2019, Scottish Event Campus, Glasgow, UK, July 29–August 2, 2019.

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Nuclear Science and Transmutation Research Division
High-Intensity Accelerator R&D Group
1. Abstract
The High-Intensity Accelerator R&D group, consisting of two teams, develops elemental technology of high-power acceleratorsand high-power targets, aiming at future applications to nuclear transmutations of long-lived fission product into short-lived nuclides.
The research subjects are superconducting rf cavities for low-velocity ions, design of high-power accelerators, high-power target
systems and related technologies.
Nuclear transmutation with high-intensity accelerators is expected to reduce the high-level radioactive wastes and to recycle
the precious resources such as rare-earth materials in future. This method is one of the important applications of the ion-accelerator
technologies that have been developed at RIKEN for a long time. Under the framework of ImPACT Fujita Program, we have conducted
R&D of elemental technology related to the high-power accelerators and high-power targets, from FY2014 to FY2018. We gained alot of experiences in these R&Ds. Among them, the development of a superconducting rf cavity has become the basis of the upgrade
program of the RILAC facility which started in 2016.

2. Major Research Subjects(1) R&D of elemental technology of high-power accelerators and high-power targets.

3. Summary of Research Activity(1) A high-gradient rf cavity has been constructed and tested based on the superconducting rf technology.
(2) Several candidates for the high-power target have been proposed and their prototypes have been tested.
(3) A high-current deuteron RFQ has been designed.

MemberGroup Director
Osamu KAMIGAITO (concurrent: Group Director, Accelerator Group)- 292 -

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Nuclear Science and Transmutation Research Division
High-Intensity Accelerator R&D Group
High-Gradient Cavity R&D Team
1. Abstract

We develop new components for accelerators dedicated for low-beta-ions with very high intensity. Specifically, we are designingand constructing a cryomodule for superconducting linac eﬃcient for acceleration of low-beta-ions. In parallel, we try to optimize an
rf acceleration system by making computer simulations for acceleration of very high intensity beams.

2. Major Research Subjects(1) Development of high-gradient cavites for low beta ions
(2) Development of power saving cryomodules

3. Summary of Research Activity• Development of highly eﬃcient superconducting accelerator modules

Members
Team Leader
Naruhiko SAKAMOTO
Research/Technical Scientists
Kazunari YAMADA
Yutaka WATANABE

Kazutaka OZEKI

Research & Development Scientist
Kenji SUDA

List of Publications & Presentations
Publications[Proceedings]
N. Sakamoto, T. Dantsuka, M. Fujimaki, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, K. Suda, A. Uchiyama, T. Watanabe,
Y. Watanabe, K. Yamada, E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara, A. Miyamoto, K. Sennyu, and T. Yanagisawa, “Development of superconducting quarter-wave resonator and cryomodule for low-beta ion accelerators at RIKEN Radioactive Isotope Beam
Factory,” Proceedings of the 19th International Conference on RF Superconductivity (SRF2019), (2019), pp. 750–757.

Presentations[International conferences/workshops]
N. Sakamoto, T. Dantsuka, M. Fujimaki, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, K. Suda, A. Uchiyama, T. Watanabe,
Y. Watanabe, K. Yamada, E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara, A. Miyamoto, K. Sennyu, and T. Yanagisawa (invited),“Development of superconducting quarter-wave resonator and cryomodule for low-beta ion accelerators at RIKEN Radioactive Isotope
Beam Factory,” 19th International Conference on RF Superconductivity (SRF2019), Dresden, Germany, June 30–July 5, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Nuclear Science and Transmutation Research Division
High-Intensity Accelerator R&D Group
High-Power Target R&D Team
1. Abstract

The subjects of this team cover R&D studies with respect to target technology for the transmutation of the LLFPs.

2. Major Research Subjects(1) Liquid lithium target for production of neutron or muon
(2) Beam window without solid structure

3. Summary of Research Activity(1) Liquid lithium target for production of neutron or muon
(H. Okuno)(2) Beam window with solid structure(H. Okuno)

MemberTeam Leader
Hiroki OKUNO

List of Publications & Presentations
Publications[Original papers]
H. Okuno, H. Sakurai, Y. Mori, R. Fujita, and M. Kawashima, “Proposal of a 1-ampere-class deuteron single-cell linac for nuclear
transmutation,” Proceedings of the Japan Academy, Series B 95, 430–439 (2019).

Presentations[International conferences/workshops]
H. Okuno (oral), “Accelerator and target for transmutation of long-lived fission products in nuclear waste,” Fourth International Workshop
on Technology and Components of Accelerator-Driven Systems (TCADS-4), Antwerp, Belgium, October 14–17, 2019.
H. Okuno (oral), “Seeking for a novel fabrication technology to make a large-bore SRF-QWR cavity for 1-ampere class linac,” TTC 2020,
Genève, Switzerland, February 4–7, 2020.

Press releasesʮʮ֩ͷΰϛʯ໰୊ղܾʹඞཁͳՃ଎‫ث‬ͷ֓೦ΛఏҊ—‫ط‬ଘͷ 300 ഒͷߴग़ྗॏཅࢠϏʔϜͷՃ଎͕Մೳʹ—ʯ, ཧ‫ݚ‬ϓϨεϦϦʔε, 2019 ೥ 8 ݄ 9 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Accelerator Group
1. Abstract

The Accelerator Group, consisting of seven teams, pursues various upgrade programs on the world-leading heavy-ion accelerator
facility, RI Beam Factory (RIBF), to enhance the accelerator performance and operation eﬃciency. The programs include the R&D
of superconducting ECR ion source, charge stripping systems, beam diagnostic devices, radiofrequency systems, control systems, andbeam simulation studies. We are also maintaining the large infrastructure to realize eﬀective operation of the RIBF. Moreover, we are
actively promoting the applications of the facility to various research fields.
Our primary mission is to supply intense, stable heavy-ion beams for the users through eﬀective operation, maintenance, andupgrade of the RIBF accelerators and related infrastructure. The director members govern the development programs that are not dealt
with by a single team, such as intensity upgrade and eﬀective operation. We also discuss the future plans of RIBF along with otherlaboratories belonging to the RIBF research division.
Various improvements and developments have been carried out for the RIBF accelerators in order to upgrade the beam intensities
and stability. Owing to the eﬀorts, for example, the intensity of the uranium beam has increased by 70% in the last three years, resulting
in the intensity of 94 pnA (7.7 kW) at the exit of the superconducting ring cyclotron. The beam intensity of 124 Xe has increased to
173 pnA, corresponding to the beam power of 7.4 kW.
In 2016, a supplemental budget was approved for the upgrade of RIBF aiming at synthesizing heavier new elements. A superconducting linac booster has been constructed at the RILAC facility with this budget under the collaboration with KEK researchers.
We also constructed a new superconducting ECR ion source at RILAC. The beam commissioning with the upgraded RILAC, which
has been named “SRILAC,” was started in January 2020. Finally, the SRILAC facility passed the facility inspection by the Nuclear
Regulatory Authority on the last day of FY2019. The accelerating cavities of the ring cyclotron, which had been suﬀered from thelow accelerating voltage, were also modified with this supplemantal budget. This modification played a key role in the increase of thebeam intensities of uranium and xenon mentioned above. We also started providing intense vanadium beams for the synthesis of a
new element [119] at GARIS II in 2017.
On the other hand, we have started a new project with RCNP, Osaka university, for the promotion of application research using
short-lived radioisotopes since 2017. A high-power target for production of 211 At is under development with RI Application ResearchGroup of RNC in the framework of this project. It will be installed and tested in the SRILAC facility in near future.
An upgrade plan of RIBF for further increasing heavy-ion beams, especially the uranium beam, has been continuously discussed.
The plan proposed recently is based on a new idea of “charge-stripper ring (CSR),” which is used to improve the overall stripping
eﬃciency of the uranium beam. This device recirculates and re-injects the uranium ions into the charge stripper until the ions become
the charge state required for the succeeding acceleration, while the bunch structure is kept with its isometric orbit lengths for all the
charge states. Design study of the whole CSR is under progress after intensive optical calculations for the circulating beam. The final
goal of this plan is to increase the uranium beam intensity by 20 times of the present value, namely up to 2000 pnA, at the exit of SRC.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Intensity upgrade of RIBF accelerators (Okuno)
Eﬀective and stable operation of RIBF accelerators (Fukunishi)
Commissioning of the upgraded RILAC (SRILAC) facility
Promotion of the future plan

3. Summary of Research Activity(1) The maximum intensities of the uranium and xenon beams reached 94 and 173 pnA, respectively, at 345 MeV/nucleon.
(2) The maximum intensity of the calcium beam reached 740 pnA at 345 MeV/nucleon, which corresponds to 12.3 kW. That of
the krypton beam reached 486 pnA, corresponding to 13.4 kW.
(3) The overall beam availability for the RIBF experiments averaged for 5 years from 2013 to 2017 was 92%. Although theavailability fell down to 79% in 2018 because of several hardware troubles, it exceeded 92% in 2019.
(4) A major upgrade of the accelerator facility has been conducted aiming at synthesizing heavier new elements. It includes
construction of a superconducting linac booster of RILAC, construction of a new superconducting ECR ion source, andmodification of the accelerating cavities of the ring cyclotron (RRC). The upgraded RILAC (SRILAC) facility passed thefacility inspection by the Nuclear Regulatory Authority, as scheduled.
(5) The large infrastructure was properly maintained based on a well-organized cooperation among the related sections.
(6) An intensity-upgrade plan of the RIBF has been further investigated. Design study of the charge-stripper ring (CSR) is underprogress.

Members
Group Director- 295 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Osamu KAMIGAITO
Deputy Group Directors
Hiroki OKUNO (for intensity upgrade)

Nobuhisa FUKUNISHI (for stable and eﬃcient operation)

Junior Research Associate
Takahiro KARINO (Utsunomiya Univ.)

Kaori NAKAMURA (The University of Tokyo)

Research Part-time Worker I
Akira GOTO

Masayuki KASE

Research Consultants
Tadashi FUJINAWA

Toshiyuki HATTORI

Visiting Scientists
Eiji KAKO (KEK)
Hirotaka NAKAI (KEK)
Kensei UMEMORI (KEK)
Hiroshi SAKAI (KEK)

Taro KONOMI (KEK)
Noboru SASAO (Okayama Univ.)
Yasutaka IMAI (Okayama Univ.)

Student Trainees
Akira FUJIEDA (Okayama Univ.)

Hiroyuki KAINO (Okayama Univ.)

Assistant
Karen SAKUMA
Administrative Part-time Worker II
Ryoko UMEZAKI

List of Publications & Presentations
Publications[Original papers]
T. Karino, “Evaluation method of beam instability in laser ion source using solenoid,” Rev. Sci. Instrum. 91, 033316 (2020).
K. Nakamura, N. Nishiura, M. Okamura, T. Kanesue, S. Ikeda, and A. Cannavo, “Feasibility study of a compact heavy ion source forinvestigation of laboratory magnetospheric plasma,” Rev. Sci. Instrum. 91, 033503 (2020).

[Proceedings]
O. Kamigaito, K. Ozeki, N. Sakamoto, K. Suda, and K. Yamada, “Measurement of mechanical vibration of SRILAC cavities,” Proceedingsof the 19th International Conference on RF Superconductivity (SRF2019), (Dresden, Germany, TUP042, 2019), pp. 515.
O. Kamigaito, T. Dantsuka, M. Fujimaki, N. Fukunishi, H. Hasebe, Y. Higurashi, E. Ikezawa, H. Imao, M. Kidera, M. Komiyama, K.
Kumagai, T. Maie, Y. Miyake, T. Nagatomo, T. Nakagawa, M. Nakamura, T. Nishi, J. Ohnishi, H. Okuno, K. Ozeki, N. Sakamoto, K.
Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, and K. Yamada, “Recent progress in RIKEN RI Beam Factory,” Proceedings of 22ndInternational Conference on Cyclotrons and their Applications (CYC2019), (Cape Town, South Africa, MOB01, 2019).

Presentations[International conferences/workshops]
O. Kamigaito (invited), “Recent progress in RIKEN RI Beam Factory,” 22nd International Conference on Cyclotrons and their Applications (CYC2019), Cape Town, South Africa, September 22–27, 2019.
T. Karino (oral), “Evaluation method of beam instability in laser ion source using solenoid,” The 18th International Conference on Ion
Sources (ICIS2019), Lanzhou, China, September 1–6, 2019.
K. Nakamura (oral), “Feasibility study of a compact heavy ion source for investigation of laboratory magnetospheric plasma,” The 18th
International Conference on Ion Sources (ICIS2019), Lanzhou, China, September 1–6, 2019.
A. Fujieda (oral), “Ba-ion spectroscopy experiment for high-intensity gamma-ray source using heavy ions,” The 12th International Workshop on Fundamental Physics Using Atoms (FPUA2020), Wako, Japan, January 9–10, 2020.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Accelerator Group
Accelerator R&D Team
1. Abstract
We are developing the key hardware in upgrading the RIBF accelerator complex. Our primary focus and research is charge
stripper which plays an essential role in the RIBF accelerator complex. Charge strippers remove many electrons in ions and realizeeﬃcient acceleration of heavy ions by greatly enhancing charge state. The intensity of uranium beams is limited by the lifetime of the
carbon foil stripper conventionally installed in the acceleration chain. The improvement of stripper lifetimes is essential to increase
beam power towards the final goal of RIBF in the future. We are developing the low-Z gas stripper. In general gas stripper is free fromthe lifetime related problems but gives low equilibrium charge state because of the lack of density eﬀect. Low-Z gas stripper, however,can give as high equilibrium charge state as that in carbon foil because of the suppression of the electron capture process. Another our
focus is the upgrade of the world’s first superconducting ring cyclotron.

2. Major Research Subjects(1) Development of charge strippers for high power beams (foil, low-Z gas)
(2) Upgrade of the superconducting ring cyclotron(3) Maintenance and R&D of the electrostatic deflection/inflection channels for the beam extraction/injection

3. Summary of Research Activity(1) Development of charge strippers for high power beams (foil, low-Z gas)
(H. Hasebe, H. Imao, H. Okuno)
We are developing the charge strippers for high intensity heavy ion beams. We are focusing on the developments on carbon or
berrilium foils and gas strippers including He gas stripper.
(2) Upgrade of the superconducting ring cyclotron(J. Ohnishi, H. Okuno)
We are focusing on the upgrade of the superconducting ring cyclotron.
(3) Maintenance and R&D of the electrostatic deflection/inflection channels for the beam extraction/injection(J. Ohnishi, H. Okuno)
We are developing high-performance electrostatic channels for high power beam injection and extraction.

Members
Team Leader
Hiroki OKUNO
Research/Technical Scientists
Hiroshi IMAO (Senior Research Scientist)
Jun-ichi OHNISHI (Senior Technical Scientist)

Hiroo HASEBE (Technical Scientist)

Special Postdoctoral Researcher
Yasuto MIYAKE
Junior Research Associate
Naoya IKOMA
Visiting Scientists
Andreas ADELMANN (Paul Sherrer Inst.)
Noriyosu HAYASHIZAKI (Tokyo Tech)

Hironori KUBOKI (KEK)

Student Trainees
Taishi SASAKI (Nagaoka Univ. of Tech.)

Yoshiki SHIKUMA (Nagaoka Univ. of Tech.)Part-time Workers
Taishi SASAKI (Research Part-time Worker II)

Yoshiki SHIKUMA (Research Part-time Worker II)- 297 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

List of Publications & Presentations
Publications[Original papers]
N. Ikoma, Y. Miyake, M. Takahashi, H. Okuno, S. Namba, K. Takahashi, T. Sasaki, and T. Kikuchi, “Demonstration of plasma window
with diameter of 20 mm and pressure separation for accelerator application,” Plasma Fusion Res. 14, 1206148 (2019).
N. Ikoma, Y. Miyake, M. Takahashi, H. Okuno, S. Namba, K. Takahashi, T. Sasaki, and T. Kikuchi, “Characteristics of plasma window
with various channel diameters for accelerator applications,” Review of Scientific Instruments 91, 053503 (2020).

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Research Facility Development Division
Accelerator GroupIon Source Team
1. Abstract
Our aim is to operate and develop the ECR ion sources for the accelerator-complex system of the RI Beam Factory. We focus on
further upgrading the performance of the RI Beam Factory through the design and fabrication of a superconducting ECR ion sourcefor production of high-intensity heavy ions.

2. Major Research Subjects(1) Operation and development of the ECR ion sources(2) Development of a superconducting ECR heavy-ion source for production of high-intensity heavy ion beams

3. Summary of Research Activity(1) Operation and development of ECR ion sources(T. Nakagawa, M. Kidera, Y. Higurashi, T. Nagatomo, Y. Kanai, and H. Haba)
We routinely produce and supply various kinds of heavy ions such as zinc and calcium ions for the super-heavy element searchexperiment as well as uranium ions for RIBF experiments. We also perform R&D’s to meet the requirements for stable supply ofhigh-intensity heavy ion beams.
(2) Development of a superconducting ECR ion source for use in production of a high-intensity heavy ion beam
(T. Nakagawa, J. Ohnishi, M. Kidera, Y. Higurashi, and T. Nagatomo)
The RIBF is required to supply heavy ion beams with very high intensity so as to produce RI’s and for super-heavy element searchexperiment. We have designed and are fabricating an ECR ion source with high magnetic field and high microwave- frequency, since
the existing ECR ion sources have their limits in beam intensity. The coils of this ion source are designed to be superconducting for the
production of high magnetic field. We are also designing the low-energy beam transport line of the superconducting ECR ion source.

Members
Team Leader
Takahide NAKAGAWA
Research/Technical Scientists
Takashi NAGATOMO (Senior Technical Scientist)
Yoshihide HIGURASHI (Technical Scientist)

Masanori KIDERA (Technical Scientist)

Special Temporary Research Scientist
Yasuyuki KANAI

List of Publications & Presentations
Publications[Original papers]
T. Nagatomo et al., “High intensity vanadium beam for synthesis of new superheavy elements with well-controlled emittance by using“slit triplet”,” Rev. Sci. Instrum. ICIS18, 023318 (2020).
A. Uchiyama et al., “Control system for the new RIKEN 28-GHz superconducting electron cyclotron resonance ion source for SRILAC,”
Rev. Sci. Instrum. ICIS18, 025101 (2020).

[Proceedings]
T. Nagatomo et al., “Development of RIKEN 28 GHz SC-ECRISs for synthesizing super-heavy elements,” Proc. HIAT2018,
doi:10.18429/JACoW-HIAT2018-TUZAA01.

Presentations[International conferences/workshops]
Y. Higurashi (invited), “Status and perspective for high intensity uranium beams from the RIKEN 28 GHz ECRIS,” ICIS2019, Lanzhou,
China, September 1–6, 2019.
T. Nakagawa (oral), “Production of intense metal ion beam with RIKEN 28 GHz SC-ECRIS,” ICIS2019, Lanzhou, China, September
1–6, 2019.
T. Nagatomo (oral), “Well-controlled emittance of the metallic ion beam extracted from the 28 GHz SC-ECRIS adopting the super
conducting acceleration cavity for new super heavy elements research,” ICIS2019, Lanzhou, China, September 1–6, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Accelerator GroupRILAC Team
1. Abstract

The operation and maintenance of the RIKEN Heavy-ion Linac (RILAC) have been carried out. There are two operation modes:
one is the stand-alone mode operation and the other is the injection mode operation. The RILAC has been used especially as an
injector for the RIKEN RI- Beam Factory accelerator complex. The RILAC is composed of the 28 GHz SC ECR ion source, thefrequency-variable RFQ linac, the frequency-variable main linac, and the SC booster linac (SRILAC).

2. Major Research Subjects(1) The long term high stability of the RILAC operation.
(2) Improvement of high eﬃciency of the RILAC operation.

3. Summary of Research Activity

The RILAC was started to supply ion beams for experiments in 1981. Thousands hours are spent in a year for delivering manykinds of heavy-ion beams to various experiments.
The RILAC has two operation modes: one is the stand-alone mode operation delivering low-energy beams directly to experiments
and the other is the injection mode operation injecting beams into the RRC. In the first mode, the RILAC supplies a very important
beam to the nuclear physics experiment of “the research of super heavy elements.” In the second mode, the RILAC plays a very
important role as upstream end of the RIBF accelerator complex.
The maintenance of these devices is extremely important in order to keep the log-term high stability and high eﬃciency of the
RILAC beams. Therefore, improvements are always carried out for the purpose of more stable and more eﬃcient operation.

Members
Team Leader
Eiji IKEZAWA
Research/Technical Scientist
Yutaka WATANABE (Senior Technical Scientist)

List of Publications & Presentations
Publications[Proceedings]
M. Tamura, E. Ikezawa, T. Ohki, H. Yamauchi, K. Oyamada, A. Yusa, K. Kaneko, Y. Watanabe, and O. Kamigaito, “Present status of
RILAC,” Proceedings of the 16th Annual Meeting of Particle Accelerator Society of Japan, (2019), pp. 1263.

Presentations[Domestic conferences]ాଜ‫࢙ڡ‬, ஑୔ӳೋ, େ໦ஐଇ, ࢁ಺‫ࢿܒ‬, খࢁా࿨޾, ༡ࠤཅ, ۚࢠ݈ଠ, ౉ᬒ༟, ্֞֎मҰ, ʢFSPI010ʣ, ʮཧ‫ݚ‬ॏΠΦϯϦχΞο
Ϋͷ‫ݱ‬ঢ়ใࠂʯ, ୈ 16 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ‫౎ژ‬, 2019 ೥ 7 ݄ 31 ೔–8 ݄ 3 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Accelerator Group
Cyclotron Team
1. Abstract

Together with other teams of Nishina Center accelerator division, maintaining and improving the RIBF cyclotron complex. The
accelerator provides high intensity heavy ions. Our mission is to have stable operation of cyclotrons for high power beam operation.
Recently stabilization of the rf system is a key issue to provide 10 kW heavy ion beam.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

RF technology for Cyclotrons
Operation of RIBF cyclotron complex
Maintenance and improvement of RIBF cyclotrons
Single turn operation for polarized deuteron beams
Development of superconducting cavity

3. Summary of Research Activity• Development of the rf system for a reliable operation• Development of highly stabilized low level rf system• Development of superconducting cavity• Development of the intermediate-energy polarized deuteron beams.

Members
Team Leader
Naruhiko SAKAMOTO
Research/Technical Scientists
Kazutaka OZEKI (Senior Technical Scientist)

Kenji SUDA (Technical Scientist)

List of Publications & Presentations
Publications[Proceedings]
K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, Y. Watanabe, K. Yamada, E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara,
A. Miyamoto, K. Sennyu, and T. Yanagisawa, “Fabrication and performance of superconducting quarter-wavelength resonators for
SRILAC,” Proceedings of the 19th International Conference on RF Superconductivity, (2019), pp. 182–187.
H. Imao, O. Kamigaito, N. Sakamoto, T. Watanabe, Y. Watanabe, K. Yamada, and K. Oyamada, “Non-evaporative getter-based diﬀerential
pumping system for SRILAC at RIBF,” Proceedings of the 19th International Conference on RF Superconductivity (2019), pp. 419–423.
K. Yamada, T. Dantsuka, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, T. Watanabe, Y. Watanabe,
E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara, A. Miyamoto, K. Sennyu, and T. Yanagisawa, “Construction of superconducting
linac booster for heavy-ion linac at RIKEN Nishina Center,” Proceedings of the 19th International Conference on RF Superconductivity,(2019), pp. 502–507.
O. Kamigaito, K. Ozeki, N. Sakamoto, K. Suda, and K. Yamada, “Measurement of mechanical vibration of SRILAC cavities,” Proceedingsof the 19th International Conference on RF Superconductivity (2019), pp. 513–517.
݄‫ݑډ‬ढ़, ෱ᖒ੟ࣇ, ᖛ஥੣, ੴ઒੝, খྛਗ਼ࢤ, খࢁ྄, ஥ଜ෢ࢤ, ੢ాູ, ੢ଜ੣, ࣲాॱᠳ, ໼෌Ұ৻, େؔ࿨‫و‬, ஈ௩஌ࢤ, ౻‫ר‬ਖ਼थ, ౻ೄխ, ෱੢ெঘ, ௕୩෦༟༤, ೔฻঵ӳ, ஑୔ӳೋ, ࠓඌߒ࢜, ্֞֎मҰ, ۚҪอ೭, Ճ੉ণ೭, ໦ࣉਖ਼‫ݑ‬, ࠐࢁඒ࡙, ‫۽‬୩‫ࢠܡ‬, ਅՈ෢࢜, ௕੉੣, ௕༑ܼ, த઒޹ल, தଜਔԻ, େ੢७Ұ, Ԟ໺޿थ, ࡔຊ੒඙, ਢా݈࢚, ಺ࢁ‫ڿ‬ਔ, ౉෦ल, ౉ᬒ‫؀‬, ౉ᬒ༟,ࢁాҰ੒, ࢁᖒलߦ, ʮཧ‫ ݚ‬RIBF ʹ͓͚ΔϦϯάαΠΫϩτϩϯͷӡసใࠂʯ, ୈ 16 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ‫౎ژ‬େֶ٢ాΩϟϯύε, (‫౎ژ‬, 2019), pp.1193–1197.
ᖛ஥੣, ෱ᖒ੟ࣇ, ੴ઒੝, খྛਗ਼ࢤ, খࢁ྄, ஥ଜ෢ࢤ, ੢ాູ, ੢ଜ੣, ࣲాॱᠳ, ݄‫ݑډ‬ढ़, ໼෌Ұ৻, ۚࢠ݈ଠ, খࢁా࿨޾, ాଜ‫࢙ڡ‬, ༡ࠤཅ, ਢా݈࢚, ౻‫ר‬ਖ਼थ, ෱੢ெঘ, ‫ޙ‬౻জ, ௕୩෦༟༤, ೔฻঵ӳ, ࠓඌߒ࢜, Ճ੉ণ೭, ্֞֎मҰ, ໦ࣉਖ਼‫ݑ‬, ࠐࢁඒ࡙,‫۽‬୩‫ࢠܡ‬, ਅՈ෢࢜, ௕੉੣, ௕༑ܼ, த઒޹ल, େ੢७Ұ, Ԟ໺޿थ, େؔ࿨‫و‬, ࡔຊ੒඙, ಺ࢁ‫ڿ‬ਔ, ౉෦ल, ౉ᬒ‫؀‬, ౉ᬒ༟, ࢁాҰ੒, খߴ߁র, େ৓޾ޫ, ʮཧ‫ ݚ‬AVF αΠΫϩτϩϯӡసͷ‫ݱ‬ঢ়ใࠂʯ, ୈ 16 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ‫౎ژ‬େֶ٢ాΩϟϯύε,(‫౎ژ‬, 2019), pp. 1224–1228.

Presentations[International conferences/workshops]
K. Ozeki (oral), “Power couplers for RIKEN superconducting QWR,” World Wide Fundamental Power Coupler meeting #5, Geneva,
Switzerland, June 25–26, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, Y. Watanabe, K. Yamada, E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara,
A. Miyamoto, K. Sennyu, and T. Yanagisawa (poster), “Fabrication and performance of superconducting quarter-wavelength resonators
for SRILAC,” 19th International Conference on RF Superconductivity (2019), Dresden, Gernany, June 30–July 5, 2019.
H. Imao, O. Kamigaito, N. Sakamoto, T. Watanabe, Y. Watanabe, K. Yamada, and K. Oyamada (poster), “Non-evaporative getter-based
diﬀerential pumping system for SRILAC at RIBF,” 19th International Conference on RF Superconductivity (2019), Dresden, Gernany,
June 30–July 5, 2019.
K. Yamada, T. Dantsuka, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, T. Watanabe, Y. Watanabe,
E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara, A. Miyamoto, K. Sennyu, and T. Yanagisawa (poster), “Construction of superconducting linac booster for heavy-ion linac at RIKEN Nishina Center,” 19th International Conference on RF Superconductivity (2019),
Dresden, Gernany, June 30–July 5, 2019.
O. Kamigaito, K. Ozeki, N. Sakamoto, K. Suda, and K. Yamada (poster), “Measurement of mechanical vibration of SRILAC cavities,”
19th International Conference on RF Superconductivity (2019), Dresden, Gernany, June 30–July 5, 2019.

[Domestic conferences/workshops]݄‫ݑډ‬ढ़, ෱ᖒ੟ࣇ, ᖛ஥੣, ੴ઒੝, খྛਗ਼ࢤ, খࢁ྄, ஥ଜ෢ࢤ, ੢ాູ, ੢ଜ੣, ࣲాॱᠳ, ໼෌Ұ৻, େؔ࿨‫و‬, ஈ௩஌ࢤ, ౻‫ר‬ਖ਼थ, ౻ೄխ, ෱੢ெঘ, ௕୩෦༟༤, ೔฻঵ӳ, ஑୔ӳೋ, ࠓඌߒ࢜, ্֞֎मҰ, ۚҪอ೭, Ճ੉ণ೭, ໦ࣉਖ਼‫ݑ‬, ࠐࢁඒ࡙, ‫۽‬୩‫ࢠܡ‬, ਅՈ෢࢜, ௕੉੣, ௕༑ܼ, த઒޹ल, தଜਔԻ, େ੢७Ұ, Ԟ໺޿थ, ࡔຊ੒඙, ਢా݈࢚, ಺ࢁ‫ڿ‬ਔ, ౉෦ल, ౉ᬒ‫؀‬, ౉ᬒ༟,ࢁాҰ੒, ࢁᖒलߦ (ϙελʔൃද), ʮཧ‫ ݚ‬RIBF ʹ͓͚ΔϦϯάαΠΫϩτϩϯͷӡసใࠂʯ, ୈ 16 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ‫ژ‬౎େֶ٢ాΩϟϯύε, ‫౎ژ‬, 2019 ೥ 7 ݄ 31 ೔–8 ݄ 3 ೔.
ᖛ஥੣, ෱ᖒ੟ࣇ, ੴ઒੝, খྛਗ਼ࢤ, খࢁ྄, ஥ଜ෢ࢤ, ੢ాູ, ੢ଜ੣, ࣲాॱᠳ, ݄‫ݑډ‬ढ़, ໼෌Ұ৻, ۚࢠ݈ଠ, খࢁా࿨޾, ాଜ‫࢙ڡ‬, ༡ࠤཅ, ਢా݈࢚, ౻‫ר‬ਖ਼थ, ෱੢ெঘ, ‫ޙ‬౻জ, ௕୩෦༟༤, ೔฻঵ӳ, ࠓඌߒ࢜, Ճ੉ণ೭, ্֞֎मҰ, ໦ࣉਖ਼‫ݑ‬, ࠐࢁඒ࡙,‫۽‬୩‫ࢠܡ‬, ਅՈ෢࢜, ௕੉੣, ௕༑ܼ, த઒޹ल, େ੢७Ұ, Ԟ໺޿थ, େؔ࿨‫و‬, ࡔຊ੒඙, ಺ࢁ‫ڿ‬ਔ, ౉෦ल, ౉ᬒ‫؀‬, ౉ᬒ༟, ࢁాҰ੒, খߴ߁র, େ৓޾ޫ (ϙελʔൃද), ʮཧ‫ ݚ‬AVF αΠΫϩτϩϯӡసͷ‫ݱ‬ঢ়ใࠂʯ, ୈ 16 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ‫౎ژ‬େֶ٢ాΩϟϯύε, ‫౎ژ‬, 2019 ೥ 7 ݄ 31 ೔–8 ݄ 3 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Accelerator GroupBeam Dynamics & Diagnostics Team
1. Abstract

Aiming at stable and eﬃcient operation of the RIBF cascaded cyclotron system, Beam Dynamics and Diagnostics Team developes
power supplies, beam instrumentation, computer control and beam dynamic studies. We have successfully increased the beam availability for user experiments to more than 90%. We have also established small-beam-loss operations. The latter strongly contributes
to recent high-power operations at RIBF.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

More eﬃcient and stable operations of the RIBF cascaded cyclotron system
Maintenance and developments of the beam instrumentation
Developments of computer control system for more intelligent and eﬃcient operations
Maintenance and improvements of the magnet power supplies for more stable operations
Upgrade of the existing beam interlock system for high-power beams with few tens of kW

3. Summary of Research Activity(1) High-intensity heavy-ion beams such as 94-pnA uranium, 173-pnA xenon, 486-pnA krypton, and 740-pnA calcium beams
have been obtained.
(2) The world-first high-Tc SQUID beam current monitor has been developed.
(3) The bending power of the fixed-frequency Ring Cyclotron has been upgraded to 700 MeV.
(4) The world-most-intense V beams are stably supplied to super-heavy-element search experiments.
(5) The RIBF control system has been operated stably by replacing legacy hardware controllers carried over from our old facility
with new ones. Several useful operation tools are also developed.
(6) The dated power supplies exciting the main coils of RIKEN Ring Cyclotron has been upgrade to a new one having a betterlong-term stability than the old ones.

Members
Team Leader
Nobuhisa FUKUNISHI
Research/Technical Scientists
Masaki FUJIMAKI (Senior Technical Scientist)
Keiko KUMAGAI (Senior Technical Scientist)
Tamaki WATANABE (Senior Technical Scientist)

Kazunari YAMADA (Senior Technical Scientist)
Akito UCHIYAMA (Technical Scientist)

Expert Technician
Misaki KOMIYAMA
Postdoctoral Researcher
Takahiro NISHI
Visiting Scientists
Shin-ichiro HAYASHI (Hiroshima Int’l Univ.)
Atsushi KAMOSHIDA (Nat’l Instruments Japan Corporation)

Takuya MAEYAMA (Kitasato Univ.)

Student Trainee
Anri MOCHIZUKI (Kitasato Univ.)
Part-time Worker
Makoto NAGASE (Research Part-time Worker I)

List of Publications & Presentations
Publications[Original papers]
A. Uchiyama, T. Nagatomo, Y. Higurashi, J. Ohnishi, M. Komiyama, K. Kumagai, M. Fujimaki, H. Yamauchi, M. Tamura, K. Kaneko,
N. Fukunishi, and T. Nakagawa, “Control system for the new RIKEN 28-GHz superconducting electron cyclotron resonance ion source
for SRILAC,” Rev. Sci. Instrum. 91, 025101 (2020).
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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53[Proceedings]
T. Watanabe, H. Imao, O. Kamigaito, N. Sakamoto, N. Fukunishi, M. Fujimaki, K. Yamada, Y. Watanabe, T. Toyama, T. Miyao, A. Miura,
K. Hanamura, T. Kawachi, R. Koyama, and A. Kamoshida, “Calibration of the beam energy and position monitor system for the
RIKEN superconducting acceleration cavity,” Proceedings of the 2019 International Beam Instrumentation Conference (IBIC2019),
Pre-Release 1–3, Malmö, Sweden, September 8–12, 2019.
K. Yamada et al., “Construction of superconducting linac booster for heavy-ion linac at RIKEN Nishina Center,” Proc. SRF2019, TUP037,
Dresden, Germany, 2019-July, p. 504.
R. Koyama, A. Uchiyama, H. Imao, and T. Watanabe, “Upgrade of gas stripper control system for system integration at RIBF,” Proceedingsof the 16th Annual Meeting of Particle Accelerator Society of Japan, 865–868, Kyoto, Japan, July 31–August 3, 2019.
A. Uchiyama, M. Komiyama, K. Kumagai, E. Ikezawa, J. Ohnishi, H. Yamauchi, and M. Tamura, “Upgrade of electromagnet power
supply control at RILAC,” Proceedings of the 16th Annual Meeting of Particle Accelerator Society of Japan, 869–872, Kyoto, Japan,
July 31–August 3, 2019.
T. Watanabe, T. Toyama, K. Hanamura, H. ImaoA, O. Kamigaito, A. Kamoshida, T. Kawachi, R. Koyama, N. Sakamoto, N. Fukunishi,
M. Fujimaki, A. Miura, T. Miyao, K. Yamada, and Y. Watanabe, “Mapping measurement for beam energy position monitor system
for RIKEN superconducting acceleration cavity,” Proceedings of the 16th Annual Meeting of Particle Accelerator Society of Japan,
1105–1108, Kyoto, Japan, July 31–August 3, 2009.

Presentations[International conferences/workshops]
K. Yamada et al. (poster), “Construction of superconducting linac booster for heavy-ion linac at RIKEN Nishina Center,” 19th International Conference on RF Superconductivity (SRF2019), Dresden, Germany, June 30–July 5, 2019.
A. Uchiyama, T. Nagatomo, Y. Higurashi, J. Ohnishi, M. Komiyama, K. Kumagai, M. Fujimaki, H. Yamauchi, M. Tamura, K. Kaneko,
N. Fukunishi, and T. Nakagawa (poster), “Control system for the new RIKEN 28-GHz superconducting electron cyclotron resonanceion source for SRILAC,” The 18th International Conference on Ion Sources (ICIS2019), Lanzhou, China, September 1–6, 2019.
T. Watanabe, H. Imao, O. Kamigaito, N. Sakamoto, N. Fukunishi, M. Fujimaki, K. Yamada, Y. Watanabe, T. Toyama, T. Miyao, A. Miura,
K. Hanamura, T. Kawachi, R. Koyama, and A. Kamoshida, “Calibration of the beam energy and position monitor system for the
RIKEN superconducting acceleration cavity,” The 2019 International Beam Instrumentation Conference (IBIC2019), Malmö, Sweden,
September 8–12.
M. Komiyama et al. (poster), “Recent updates of the RIKEN RI Beam Factory control system,” The17th Biennial International Conferenceon Accelerator and Large Experimental Physics Control Systems (ICALEPCS 2019), New York, USA, October 5–11, 2019.
K. Yamada (oral), “Cryomodule design, assembly and installation utilizing KOACH system,” TESLA Technology Collaboration (TTC)
Meeting 2020 at CERN, Geneva, Switzerland, February 4–7, 2020.

[Domestic symposium]
M. Komiyama, A. Uchiyama, and K. Kumagai (poster), “Beam Interlock System of RIKEN RI Beam Factory,” 7th Accelerator Facility
Safety Symposium, Tokai, Ibaragi, Japan, January 23–24, 2020.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Accelerator Group
Cryogenic Technology Team
1. Abstract
We are operating the cryogenic system for the superconducting ring cyclotron in RIBF. We are operating the helium cryogenic
system in the south area of RIKEN Wako campus and delivering the liquid helium to users in RIKEN. We are trying to collecteﬃciently gas helium after usage of liquid helium.

2. Major Research Subjects(1) Operation of the cryogenic system for the superconducting ring cyclotron in RIBF.
(2) Operation of the helium cryogenic plant in the south area of Wako campus and delivering the liquid helium to users in Wako
campus.

3. Summary of Research Activity(1) Operation of the cryogenic system for the superconducting ring cyclotron in RIBF
(H. Okuno, T. Dantsuka, M. Nakamura, T. Maie).
(2) Operation of the helium cryogenic plant in the south area of Wako campus and delivering the liquid helium to users in Wako
campus.
(T. Dantsuka, S. Tsuruma, M. Kuroiwa, M. Takahashi, H. Okuno).

Members
Team Leader
Hiroki OKUNO
Research/Technical Scientists
Masato NAKAMURA (Senior Technical Scientist)
Expert Technicians
Tomoyuki DANTSUKA

Takeshi MAIE

Part-time Workers
Mamoru TAKAHASHI (Research Part-time Worker I)
Shizuho TSURUMA (Administrative Part-time Worker I)

Mayumi KUROIWA (Administrative Part-time Worker II)- 305 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Accelerator Group
Infrastructure Management Team
1. Abstract
Our team is in charge of operation, maintenance, and monitoring of research infrastructure of the whole RIBF, such as coolingwater system, air conditioner system, building equipment, and so on. It is very important to keep these infrastructures working properly
for the eﬀective and eﬃcient operation of RIBF.
We are also involved in the planning of the RIBF beam time, which is conducted by the RIBF User Liaison Team, through theestimation of the utility costs such as the electricity and the gas used for the power generator. Another important mission of our teamis to coordinate large-scale repair works carried out by the RIKEN Facility Section so that the beam time can proceed smoothly.
In the last three years, there were big construction works related to the upgrade project of the RILAC facility. We carried out thedesign of the SRF test facility, took part in the design work of the new building for radioisotope purification, jointly designed the ion
source room, and so on. The transfer work of GARIS II and the room-temperature cavities of the RILAC booster was conducted byour team.

2. Major Research Subjects(1) Operation, maintenance and monitoring of infrastructure of RI Beam Factory.
(2) Participation in the beam time planning through utility cost estimation.
(3) Coordination of large construction work and modification related to RI Beam Factory.

Members
Team Leader
Osamu KAMIGAITO (concurrent: Group Director, Accelerator Group)
Deputy Team Leader
Yutaka WATANABE (concurrent: Senior Technical Scientist,
RILAC Team.)Special Temporary Technical Scientist
Shu WATANABE
Special Temporary Employee
Hideyuki YAMASAWA

List of Publications & Presentations
Publications[Proceedings]
K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, Y. Watanabe, K. Yamada, E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara,
A. Miyamoto, K. Sennyu, and T. Yanagisawa, “Fabrication and performance of superconducting quarter-wavelength resonators for
SRILAC,” Proceedings of the 19th International Conference on RF Superconductivity (SRF2019), Dresden, Germany, MOP055, 182(2019).
H. Imao, K. Yamada, N. Sakamoto, T. Watanabe, Y. Watanabe, O. Kamigaito, and K. Oyamada, “Non-evaporable getter-based diﬀerential pumping system for SRILAC at RIBF,” Proceedings of the 19th International Conference on RF Superconductivity (SRF2019),
Dresden, Germany, TUP013, 419 (2019).
K. Yamada, T. Dantsuka, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, T. Watanabe, Y. Watanabe,
E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara, A. Miyamoto, K. Sennyu, and T. Yanagisawa, “Construction of superconducting
linac booster for heavy-ion linac at RIKEN Nishina Center,” Proceedings of the 19th International Conference on RF Superconductivity(SRF2019), Dresden, Germany, TUP037, 504 (2019).
N. Sakamoto, T. Dantsuka, M. Fujimaki, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, K. Suda, A. Uchiyama, T. Watanabe,
Y. Watanabe, K. Yamada, E. Kako, H. Nakai, H. Sakai, K. Umemori, H. Hara, A. Miyamoto, K. Sennyu, and T. Yanagisawa, “Development of superconducting quarter-wave resonator and cryomodule for low-beta ion accelerators at RIKEN Radioactive Isotope Beam
Factory,” Proceedings of the 19th International Conference on RF Superconductivity (SRF2019), Dresden, Germany, WETEB1, 752(2019).
O. Kamigaito, T. Dantsuka, M. Fujimaki, N. Fukunishi, H. Hasebe, Y. Higurashi, E. Ikezawa, H. Imao, M. Kidera, M. Komiyama,
K. Kumagai, T. Maie, Y. Miyake, T. Nagatomo, T. Nakagawa, M. Nakamura, T. Nishi, J. Ohnishi, H. Okuno, K. Ozeki, N. Sakamoto,
K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, and K. Yamada, “Recent progress in RIKEN RI Beam Factory,” Proceedings of
22nd International Conference on Cyclotrons and their Applications (CYC2019), Cape Town, South Africa, MOB01, (2019).

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N. Tsukiori, K. Ozeki, S. Fukuzawa, M. Hamanaka, S. Ishikawa, K. Kobayashi, R. Koyama, T. Nakamura, M. Nishida, M. Nishimura,
J. Shibata, K. Yadomi, T. Dantsuka, M. Fujimaki, T. Fujinawa, N. Fukunishi, H. Hasebe, Y. Higurashi, E. Ikezawa, H. Imao, O. Kamigaito, Y. Kanai, M. Kase, M. Kidera, M. Komiyama, K. Kumagai, T. Maie, M. Nagase, T. Nagatomo, T. Nakagawa, M. Nakamura,
J. Ohnishi, H. Okuno, N. Sakamoto, K. Suda, A. Uchiyama, S. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, and H. Yamasawa,“Status Report on the Operation of RIBF Ring Cyclotron,” Proceedings of the 16th Annual Meeting of Particle Accelerator Society ofJapan (PASJ2019), July 31–August 3, 2019, Kyoto, Japan, FSPH002, 1193 (2019).
M. Hamanaka, K. Suda , A. Goto, J. Ohnishi, Y. Oshiro, S. Fukuzawa, S. Ishikawa, R. Koyama, T. Nakamura, M. Nishida, M. Nishimura,
J. Shibata, N. Tsukiori, K. Yadomi, K. Kaneko, K. Oyamada, M. Tamura, Akira Yusa, M. Fujimaki, N. Fukunishi, H. Hasebe, Y. Higurashi, H. Imao, M. Kase, O. Kamigaito, M. Kidera, M. Komiyama, K. Kumagai, T. Maie, M. Nagase, T. Nagatomo, T. Nakagawa,
H. Okuno, K. Ozeki, N. Sakamoto, A. Uchiyama, S. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, and Y. Kotaka, “Status report on the operation of RIKEN AVF Cyclotron,” Proceedings of the 16th Annual Meeting of Particle Accelerator Society of Japan(PASJ2019), July 31–August 3, 2019, Kyoto, Japan, FSPH010, 1224 (2019).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Instrumentation Development Group
1. Abstract
This group develops core experimental installations at the RI Beam factory. Three projects are currently going on. SLOWRI is anexperimental installations under testing and a common element enabling multiple-use. This will stop high-energy RI beams in a gascatcher system and re-accelerates up to several-tenth keV, and the high-quality cold RI beam will be delivered to the users. SCRIT is
the world first facility for an electron scattering oﬀ unstable nuclei, and has been constructed independently of the RIBF main facility.
The first physic result was demonstrated in 2017, and the facility is now under upgrading of the electron beam power driving the RI
beam production. Rare-RI Ring is an event-by-event operated heavy-ion storage ring aiming at the precision mass measurement for
extremely rare exotic nuclei. This is now open for an experimental proposal application, and has already performed PAC-approved
experiments, and an improvement for higher precise mass measurement is now going on. All instrumentations were designed tomaximize the research potential of the world’s most intense RI beams, and the exclusive equipment available at the RI Beam Factorymakes experimental challenges possible. Technologies and experiences accumulated in this group will be able to provide opportunitiesof new experimental challenges and the foundation for future developments of RIBF.

2. Major Research Subjects
(1)
(2)
(3)
(4)

SCRIT Project
SLOWRI Project
Rear RI Ring Project
RUNBA project (Beam recycling development)

3. Summary of Research Activity
We are developing beam manipulation technology in carrying out above listed project. They are the high-quality slow RI beam
production (SCRIT and SLOWRI), the beam cooling and stopping (SCRIT and SLOWRI), and the beam accumulation technology(Rare RI Ring) in a storage ring. The technological knowhow accumulated in our projects will play a significant role in the next
generation RIBF. Status and future plan for each project is described in subsections. The electron scattering from 132 Xe isotopes has
been successfully measured and the nuclear charge density distribution has been obtained in SCRIT. We are ready for the electrons
scattering experiments for unstable nuclei. Rare RI Ring has been commissioned and the performances has been evaluated. We
have demonstrated a mass-measurement capability of R3 and successfully started mass-measurements for unknown-mass nuclei inthe experiments approved by PAC. Recently, we succeeded in measurement of masses of 74, 76 Ni, 122 Rh, and 124 Pd for the first time.
SLOWRI is now under test experiments to establish a slow RI beam production using two types of gas cells. PALIS has beencommissioned from 2015, and basic functions such as, for instance, the RI-beam stopping in Ar gas cell and the extraction from thegas cell have beam evaluated. RF ion-guide gas cell is now under testing and it will be online-commissioned in this year. Future plans
for these projects are described in subsections.
We have started a new project from last year. According to the future plan of Nishina center, we are going to develop a beam
re-cycling technique. A circulation of an RI beam in a storage ring equipped by a thin internal target is maintained until that somenuclear reaction happen at the target. The circulating beam losses the energy and the emittance grows up turn by turn because ofexisting internal target. In order to establish a beam re-cycling technique, the energy loss and growth of the energy-spread and theemittance have to be compensated by using a re-acceleration system and a beam-cooling or a fast feedback system. A beam re-cycling
technique is supposed to greatly enhance an RI use eﬃciency in a nuclear physics study. As a first step for the development of thesenovel technique, we will construct a testbench consisting of a relatively small size of heavy-ion storage ring that will be connect
to our ISOL (ERIS) in SCRIT facility. This ring named RUNBA (Recycled-Unstable-Nuclear Beam Accumulator) is equipped byacceleration devices and beam-cooling devices necessary in our R&D study. It was originally constructed as a beam cooler ring (sLSR) at the Institute for Chemical Research (ICR), Kyoto University more than ten years ago. This has been already moved to RIBF
in last year, and will be re-constructed by the SCRIT system in following year. Technical development for key devices required in
RUNBA such as a charge breeder, an energy-spread compensator, and an internal target system have been already started under the
research cooperation agreement with ICR Kyoto University.

Members
Director
Masanori WAKASUGIContract Researcher
Ryo OGAWARA- 308 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Visiting Scientists
Yasushi ABE (Nat’l Inst. of Radiological Sci.)
Akira OZAWA (Tsukuba Univ.)

Fumi SUZAKI (JAEA)

Student Trainees
So Sato (Rikkyo Univ.)

Shu TAKAGI (Kyoto Univ.)

Part-time Worker
Midori TAKEMON (Administrative Part-time Worker I)

List of Publications & Presentations
Publications and presentations are listed in subsections.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Instrumentation Development GroupSLOWRI Team
1. Abstract

SLOWRI is a universal low-energy RI-beam facility at RIBF that provides a wide variety of short-lived nuclei as high-purity andlow-emittance ion beams or stored ions in a trap, including a parasitic operation mode. The SLOWRI team develops and manages
the facility and performs high-precision spectroscopy experiments. The construction of the SLOWRI facility began in FY2013 andcommissioning work is ongoing. From April 1st in FY2019, SLOWRI has been started to be co-operated under RNC and WNSC/KEK
collaboration.
High-energy radioactive ion beams from the projectile fragment separator BigRIPS are thermalized in a large He gas catcher cell
(RFC cell) or in a small Ar gas catcher cell (PALIS cell). From these gas cells, the low-energy ion beams will be delivered via mass
separators and switchyards to various devices: such as an ion trap, a collinear fast beam apparatus, and a multi-reflection time of flightmass spectrograph. A multi-reflection time-of-flight mass spectrograph (MRTOF) has been also developed.
Two mass measurement projects using MRTOF mass spectrographs have been started: one is for trans uranium elements at the
GARIS facility and the other is for r-process nuclides at SLOWRI facility. At GARIS-II, we installed second prototype SLOWRI
combined with MRTOF, which is a medium-sized cryogenic RF-carpet He gas cell. Using second prototype SLOWRI, more than 80
nuclear masses have been measured including first mass measurements of Md and Es isotopes. In FY2019, the mass measurement for257
Db has been successfully performed at GARIS-II, and the mass has been directly determined for the first time. At SLOWRI facility,
third prototype SLOWRI is under construction, which is a 50-cm-long RF-carpet-type He gas cell combined with MRTOF. The third
prototype will be installed at F11 of BigRIPS, downstream of ZeroDegree spectrometer, which can provide symbiotic measurementswith other BigRIPS experiments.
Parallelly, the on-line commissioning for PALIS has been continuously performed at F2 of BigRIPS. For the optimization of
optical components on SLOWRI beam line, which connects between these gas cells installed at BigRIPS and an experimental room,
a compact cesium ion source was installed at the upstream of the beam line in FY2019.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Construction of the stopped and low-energy RI-beam facility, SLOWRI.
Development of a multi-reflection time-of-flight mass spectrograph for precision mass measurements of short-lived nuclei.
Development of collinear laser spectroscopy apparatus.
Development of a parasitic slow RI-beam production method using resonance laser ionization.
Commissioning for SLOWRI beam line.

3. Summary of Research Activity(1) Construction of stopped and low-energy RI-beam facility (SLOWRI)SLOWRI consists of two gas catchers (RF carpet gas cell and PALIS gas cell), mass separators a 50-m-long beam transport line,
a beam cooler-buncher, an isobar separator, and a laser system. The RF carpet gas cell will be installed at the exit of the D5 dipole
magnet of BigRIPS. The gas catcher contains a large cryogenic He gas cell with a large traveling wave rf-carpet. The PALIS gas cellis installed in the vicinity of the second focal plane slit of BigRIPS. It will provide parasitic RI-beams from those ions lost in the slits
during other experiments. In this gas catcher, thermalized RI ions quickly become neutral and will be re-ionized by resonant laser
radiations. Oﬀ- and on-line commissioning is underway.
Based on test experiments with the prototype setups, the RF-carpet gas cell contains a three stage rf-carpet structure: a gutter rf
carpet (1st carpet) for the collection thermal ions in the cell into a small slit, a narrow (about 10 mm) traveling-wave rf-carpet (2ndcarpet) for collection of ions from the gutter carpet and for transporting the ions towards the exit, and a small rf carpet for extraction
from the gas cell. In FY2019, we modified the 1st carpet to have a finer pitch which was reduced by 20% compared with the previous
version, in order to improve the transport eﬃciency. We tested the transport performance of the new 1st carpet using Cs+ ions provided
with a surface ionization ion source installed inside the gas cell. As the result, we have successfully achieved 80% transport eﬃciency
in a He gas of 133 mbar. As combined with a transport eﬃciency on the 2nd carpet, we confirmed more than 70% extraction eﬃciency
from the gas cell for the Cs+ ions which were collected onto the RF carpets.
We will install the RF-carpet gas cell combined with MRTOF at F11 of BigRIPS at first, where the on-line commissioning andsystematic mass measurements will be started from FY2020. At F11, symbiotic measurements with other BigRIPS experiments such
as HiCARI projects can be performed.
(2) Development of a multi-reflection TOF mass spectrograph for short-lived nuclei
The atomic mass is one of the most important quantities of a nucleus and has been studied in various methods since the earlydays of modern physics. From among many methods we have chosen a multi-reflection time-of-flight (MRTOF) mass spectrometer.
Slow RI beams extracted from the RF ion-guide are bunched and injected into the spectrometer with a repetition rate of ∼100 Hz. A
mass-resolving power of 170,000 has been obtained with a 2 ms flight time for 40 K and 40 Ca isobaric doublet. This mass-resolving
power should allow us to determine ion masses with an accuracy of ≤10−7 .
The MR-TOF mass spectrograph has been placed under the GARIS-II separator aiming at direct mass measurements of trans-- 310 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

uranium elements. A medium-sized cryogenic He gas cell was placed at the focal plane of GARIS-II and a bunched low-energy heavy
ion beam was transported to the trap of MRTOF. Mass measurements of more than 80 nuclides, including short-lived (T 1/2 = 10 ms)
isotopes of Ra and several isotopes of the trans-uranium elements Fm, Es, No and Md were performed in collaboration with Wako
Nuclear Science Center (WNSC) of KEK and Super Heavy Element Synthesis team of RIKEN. In FY2019, the mass measurement of
a super heavt element of 257 Db has been successfully performed, and the mass has been dilectly measured for the first time.
A new MRTOF has been assembled in FY2019 to be coupled with the third SLOWRI protype gass cell, which will be installed at
F11 of BigRIPS. Using an ion source of K+ , the oﬄine commissioning has been sucessflully performed. As the result, an impressive
mass- resolving power of 570,000 has been achived.
(3) Development of collinear fast beam apparatus for nuclear charge radii measurements
The root-mean-square charge radii of unstable nuclei have been determined exclusively by isotope shift measurements of the
optical transitions of singly charged ions or neutral atoms by laser spectroscopy. Many isotopes of alkali, alkali-earth, and noble-gas
elements in addition to several other elements have been measured by collinear laser spectroscopy since these ions all have good
optical transitions and are available at conventional ISOL facilities. However, isotopes of other elements, especially refractory andshort-lived ones, have not been investigated so far.
In SLOWRI, isotopes of all atomic elements will be provided as well collimated, mono-energetic ion beams. This should expand
the range of nuclides available for laser spectroscopy. In the first years of the RIBF project, elements in the vicinity of Ni, suchas Ni, Co, Fe, Cr, Cu, Ga, and Ge are planned to be investigated. They all have possible optical transitions in the ground states ofneutral atoms with presently available laser systems. Some of them have so called recycling transitions, which enhance the detection
probabilities noticeably. Furthermore, the multistep resonance ionization (RIS) method can be applied to the isotopes of Ni as well as
those of some other elements. The required minimum intensity for this method can be as low as 10 atoms per second.
An oﬀ-line mass separator and a collinear fast beam apparatus with a large solid-angle fluorescence detector was built previously.
A 617-nm transition of the metastable Ar+ ion at 20 keV was measured with both collinear and anti-collinear geometry, which allowed
determination of the absolute resonant frequency of the transition at rest with a relative accuracy better than 10−8 . A new setup isunder preparation at the SLOWRI experiment area in collaboration with the Ueno nuclear spectroscopy laboratory.
(4) Development of parasitic slow RI-beam production scheme using resonance laser ionization
More than 99.9% of RI ions produced in projectile fission or fragmentation are simply dumped in the first dipole magnet and theslits. A new scheme, named PALIS, meant to rescue such precious RI using a compact gas catcher cell and resonance laser ionization,
was proposed as a part of SLOWRI. The thermalized RI ions in a cell filled with Ar gas can be quickly neutralized and transported
to the exit of the cell by gas flow. Irradiation of resonance lasers at the exit ionizes neutral RI atoms eﬃciently and selectively. The
resonance ionization scheme itself can also be a useful method to perform hyperfine structure spectroscopy of RI of many elements.
In FY2019, we had two on-line experiments and a part of the experimental result was published in Prog. Theor. Exp. Phys. (Seeour publication list) Technical developments are under progress in on- and oﬀ-line commissioning.
(5) Commissioning for SLOWRI beam line
SLOWRI beam line composes of four dipole magnets, two focal plane chambers, 62 electrostatic quadrupole singlets, 11 electrostatic quadrupole quartets and 7 beam profile monitors. The hardware construction has been almost finished. In order to tune theoptical components, a compact ion source, which can be used as a side-inserted type device, has been installed at the upstream of thebeam line. We will start the tuning for the beam line using Cs+ ions provided from the ion source in FY2020.

Members
Team Leader
Hironobu ISHIYAMA
Research/Technical Scientists
Takao KOJIMA (Senior Research Scientist)
Aiko TAKAMINE (Research Scientist)

Tetsu SONODA (Technical Scientist)

Expert Technician
Takeshi MAIE
Junior Research Associate
Shun IIMURA
Visiting Scientists
Hideki IIMURA (JAEA)
Kunihiro OKADA (Sophia Univ.)
Mikael REPONEN (Univ. of Jyvaskyla)
Hans SCHUESSLER (Texas A&M Univ.)

Volker SONNENSCHEIN (Nagoya Univ.)
Minoru TANIGAKI (Kyoto Univ.)
Hideki TOMITA (Nagoya Univ.)
Hermann WOLLNIK (Univ. of Giessen)Student Trainees- 311 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Ryunosuke KODAMA (Univ. of Electro-Commun.)

Kento SUZUKI (Univ. of Electro-Commun.)Part-time Workers
Ichirou KATAYAMA (Research Part-time Worker I)

Marco ROSENBUSCH (Research Part-time Worker I)

List of Publications & Presentations
Publications[Original papers]
T. Sonoda, I. Katayama, M. Wada, H. Iimura, V. Sonnenschein, S. Iimura, A. Takamine, M. Rosenbusch, T. M. Kojima, D. S. Ahn,
N. Fukuca, T. Kubo, S. Nishimura, Y. Shimizu, H. Suzuki, H. Takaeda, M. Tanigaki, H. Tomita, K. Yoshida, and H. Ishiyama, “Conceptual study on parasitic low-energy RI beam production with in-flight separator BigRIPS and the first stopping examination for high-energy RI beam in the parasitic gas cell,” Progress of Theoretical and Experimental Physics, 2019-11, 113D02, (2019).
M. Rosenbusch, M. Wada, P. Schury, Y. Ito, H. Ishiyama, S. Ishizawa, Y. Hirayama, S. Kimura, T. M. Kojima, H. Miyatake, J. Y. Moon,
T. Niwase, T. Sonoda, A. Takamine, Y. X. Watanabe, and H. Wollnik, “A new multi-reflection time-of-flight mass spectrograph for the
SLOWRI facility,” Nucl. Instrum. Methods Phys. Res. B 463, 184–188 (2020).
P. Aschere, N. Althubiti, D. Atanasov, K. Blaum, R. B. Cakirli, S. Grevy, F. Herfurth, S. Kreim, D. Lunney, V. Manea, D. Neidherr,
M. Rosenbusch, L. Schweikhard, A. Welker, F. Wienholtz, R. N. Wolf, and K. Zuber, “Mass measurements of neutron-rich isotopes
near N = 20 by in trap decay with the ISOLTRAP spectrometer,” Phys. Rev. C 100, 014304 (2019).
H. Wollnik, M. Wada, P. Schury, M. Rosenbusch, Y. Ito, and H. Miyatake, “Time-of-flight mass spectrographs of high mass resolving
power,” International Journal of Modern Physics A, doi:10.1142/S0217751X19420016, (2019).
T. Niwase, M. Wada, P. Schury, H. Haba, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Miyatake, K. Moromoto, K. Morita, M. Rosenbusch,
H. Wollnik, T. Shanley, and Y. Benari, “Development of an alpha-TOF detector for correlated measurement of atomic masses and decay
properties,” Nucl. Instrum. Methods Phys. Res. A 953, 163198 (2020).
P. Schury, M. Wada, H. Wollnik, J. -Y. Moon, T. Hashimoto, and M. Rosenbusch, “High-stability, high-voltage power supplies for use
with multi-reflection time-of-flight mass spectrographs,” Rev. Sci. Instrum. 91, 014702 (2020)
S. Sels, P. Fischer, H. Heylem, V. Lagaki, S. Lechner, F. M. Maier, P. Plattner, M. Rosenbusch, F. Wienholts, R. N. Wolf, W. Nortershauser,
L. Schweikhard, and S. Malbrunot-Ettenauer, “First steps in the development of the multi ion reflection apparatus for collinear laser
spectroscopy,” Nucl. Instrum. Methods Phys. Res. B 463, 310–314 (2020).
S. Lechner, P. Fischer, H. Heylen, V. Lagaki, F. Maier, P. Plattner, M. Rosenbush, S. Sels, F. Wienholtz, R. N. Wolf, W. Nortershauser,
L. Schweikhard, and S. Malbrunot-Ettenauer, “Fluorescence detection as a new diagnostics tool for electrostatic ion beam traps,”
Hyperfine Interactions 240, 95 (2019).
Y. Hirayama, Y. X. Watanabe, M. Mukai, P. Schury, M. Ahmed, H. Ishiyama, S. C. Jeong Y. Kakiguchi, S. Kimura, J. Y. Moon, M. Oyaizu,
J. H. Park, M. Wada, and H. Miyatake, “Nuclear spectroscopy of r-process nuclei using KEK Isotope Separation System,” Nucl. Instrum.
Methods Phys. Res. A 463, 425–430 (2020).
M. Mukai, Y. Hirayama, P. Schury, Y. X. Watanabe, M. Ahmed, H. Haba, H. Ishiyama, S. C. Jeong, Y. Kakiguchi, S. Kimura, J. Y. Moon,
M. Oyaizu, A. Ozawa, J. H. Park, H. Ueno, M. Wada, and H. Miyatake, “Development of a multi-segmented proportional gas counterfor beta-decay spectroscopy at KISS,” Nucl. Instrum. Methods Phys. Res. B 463, 421–424 (2020).
N. Kimura, R. Kodama, K. Suzuki, S. Oishi, M. Wada, K. Okada, N. Ohmae, H. Katori, and N. Nakamura, “Direct determination of theenergy of the first excited fine structure level in Ba6+ ,” Phys. Rev. A 100, 052508, (2019)[Proceedings]
Y. X. Watanabe, Y. Hirayama, P. Schury, Y. Kakiguchi, M. Oyaizu, M. Wada,M. Miyatake, M. Mukai, S. Kimura, H. Ishiyama, S. C. Jeong,
J. Y. Moon, and J. H. Park, “Production of neutron-rich nuclei by multinucleon transfer reactions at KISS project” Exotic Nuclei, 486–
491 (2019).
Y. X. Watanabe, Y. Hirayama, M. Mukai, M. Ahmed, Y. Kakiguchi, H. Miyatake, M. Oyaizu, P. Schury, M. Wada, S. Kimura, H. Ishiyama,
S. C. Jeong, J. Y. Moon, and J. H. Park, “Experimental studies of neutron-rich nuclei around N = 126 at KEK isotope separation system,”
EPJ Web Conf. 223, 01069 (2019).

Presentations[International conferences/workshops]
H. Tomita, V. Sonnenschein, R. Terabayashi, M. Ohashi, S. Kato, S. Suzuki, K. Saito, Y. Matsui, T. Sakazaki, T. Iguchi, N. Nishizawa,T. Sonoda, H. Ishiyama, and K. Yoshida (poster), “Development of frequency comb based laser absorption/ionization spectroscopy ofradioactive isotopes”, International Conference on Laser Probing (PLATAN 2019), Helmholz Institute, Mainz, May 19–24, 2019.
A. Takamine (invited), “Recent progress in the development of gas cells, and SHE results combining GARIS with GASCELL + MRTOF”,
Expert Meeting on Next-Generation in-Flight Separators, GSI FAIR, Darmstadt, Germany, October 1, 2019.
H. Ishiyama (invited), “Present status of SLOWRI”, RIBF Users Meeting 2019, RIKEN, Japan, September 4, 2019.
H. Ishiyama (invited), “Present status of SLOWRI”, SSRI-PNS collaboration meeting 2019, RIKEN, Japan, September 4, 2019.
S. Iimura, A. Takamine, J. Liu, S. Chen, M. Rosenbusch, M. Wada, and H. Ishiyama (poster), “Development of gas cell to stop and collecthigh energy RI beam, and extract radioactive ions with a high eﬃciency”, The ALL RIKEN Workshop 2019, RIKEN, Japan, December
5–6, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53[Domestic conferences/workshops]෋ాӳੜ, V. Sonnenschein, Ճ౻߂ଠ࿠, ࣉྛྏฏ, ੢ᖒయ඙, Ҫ‫ޱ‬఩෉, M. Reponen, Ԃా఩, ੴࢁത߃, ࿨ాಓ࣏, ยࢁҰ࿠, ஛ాߒ೭, ླ໦ߒ, ਗ਼ਫཅฏ, ٢ాޫҰ, ൧ଜल‫ل‬, ߴๆѪࢠ, M. Rosenbuch, খౡོ෉, ‫ٱ‬อහ޾, K. Wendt (‫ޱ‬಄ൃද), ʮཧԽֶ‫ڀݚ‬
ॴ RI ϏʔϜϑΝΫτϦʔ௿଎ RI ϏʔϜੜ੒૷ஔʹ͓͚Δ‫ڞ‬໐ΠΦϯԽϨʔβʔΠΦϯ‫ݯ‬ͷ։ൃʯ, ࣍ੈ୅์ࣹઢγϯϙδ΢Ϝ
2019, ट౎େֶ౦‫ژ‬, ౦‫ژ‬, 2019 ೥ 8 ݄ 8–9 ೔.
൧ଜढ़ (‫ޱ‬಄ൃද), ʮཧ‫ ݚ‬BigRIPS SLOWRI ʹ͓͚Δ RF ΧʔϖοτΨεηϧͷ։ൃʯ, ‫ژ‬େෳ߹‫ݚ‬ઐ໳‫ڀݚ‬ձʮ୹ण໋֩ RI Λ༻͍ͨ֩෼ޫͱ֩෺ੑ‫ ڀݚ‬VIʯ݉ʮୈ 11 ճఀࢭɾ௿଎ RI ϏʔϜΛ༻͍ͨ֩෼ޫ‫ڀݚ‬ձʯ, ‫ژ‬େෳ߹‫ݚ‬, ‫౎ژ‬, 2020 ೥ 1 ݄ 16–17 ೔.
ߴๆѪࢠ (‫ޱ‬಄ൃද), ʮ֩ɾ෺࣭Պֶ‫΁ڀݚ‬ͷԠ༻Λ໨ࢦͨ͠ߴภ‫ ۃ‬RI ϏʔϜੜ੒ʯ, ‫ژ‬େෳ߹‫ݚ‬ઐ໳‫ڀݚ‬ձʮ୹ण໋֩ RI Λ༻͍ͨ֩෼ޫͱ֩෺ੑ‫ ڀݚ‬VIʯ݉ʮୈ 11 ճఀࢭɾ௿଎ RI ϏʔϜΛ༻͍ͨ֩෼ޫ‫ڀݚ‬ձʯ, ‫ژ‬େෳ߹‫ݚ‬, ‫౎ژ‬, 2020 ೥ 1 ݄ 16–17 ೔.
ੴࢁത߃ (‫ޱ‬಄ൃද), ʮ์ࣹੑτϨʔαʔ 8 Li ๏Ͱ‫ݻ‬ମి஑ք໘ͷϦν΢Ϝ֦ࢄ͸௥੻Մೳ͔ʁʯ, ‫ژ‬େෳ߹‫ݚ‬ઐ໳‫ڀݚ‬ձʮ୹ण໋
֩ RI Λ༻͍ͨ֩෼ޫͱ֩෺ੑ‫ ڀݚ‬VIʯ݉ʮୈ 11 ճఀࢭɾ௿଎ RI ϏʔϜΛ༻͍ͨ֩෼ޫ‫ڀݚ‬ձʯ, ‫ژ‬େෳ߹‫ݚ‬, ‫౎ژ‬, 2020 ೥ 1
݄ 16–17 ೔.

Outreach activities
H. Ishiyama (school master), S. Iimura (school staﬀ), and T. Kojima (school staﬀ), Nishina School 2019, Riken, Wako, Japan, July
30–August 1, 2019.

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Research Facility Development Division
Instrumentation Development Group
Rare RI-ring Team
1. Abstract

The aim of Rare-RI Ring (R3) is to measure the masses of short-lived unstable nuclei far from the beta-stability line. In particular,a high-precision mass measurement for nuclei located around the r-process pass (rare-RI) is required in nucleosynthesis point of view.
The R3 completed the construction at the end of 2014, and has been performed commissioning experiments several times by 2017.
Through the commissioning experiments, we confirmed the high ability of R3 as a storage ring capable of handling one event, anddemonstrated that it is possible to perform the time-of-flight Isochronous Mass Spectrometry (IMS) in shorter than 1 ms. We haveacquired an adequate eﬃciency to conduct the mass measurement experiments in the end of 2017. In 2018, we have successfully
conducted the first mass measurement experiment for 74, 76 Ni, 122 Rh, 123, 124 Pd, and 125 Ag. The analysis is in progress for giving
the new experimental mass values of 74, 76 Ni, 122 Rh, 124 Pd, and for improving the experimental mass values of 123 Pd, 125 Ag. The
remaining issues as the R3 facility are further improvement of experimental eﬃciency and that of mass measurement precision. In
2019, we started eﬀorts to resolve those issues.

2. Major Research Subjects(1) Further improvement of experimental eﬃciency and mass measurement precision(2) Precision mass measurement for rarely produced isotopes related to r-process

3. Summary of Research Activity

In the commissioning experiments up to 2017, we confirmed the unique performances of R3 and demonstrated the time-of-flightisochronous mass measurement method. The ring structure of R3 was designed with a similar concept of a separate-sector ring
cyclotron. It consists of six sectors and straight sections, and each sector consists of four rectangular bending magnets. Two magnets
at both ends of each sector are additionally equipped with ten trim coils to form a precise isochronous field. We have realized informing the precise isochronous field of 5 ppm with wide momentum range of ∆p/p = ±0.5%. Another performance required forR3 is to eﬃciently seize hold of an opportunity of the mass measurement for rare-RIs produced unpredictably. It was realized byconstructing the Isotope-Selectable Self-trigger Injection (ISSI) scheme which pre-identified rare-RI itself triggers the injection kicker
magnets. Key device was an ultra-fast response kicker system that has been successfully developed. Full activation of the kicker
magnetic field can be completed within the flight time of the rare-RI from an originating point (F3 focal point in BigRIPS) of thetrigger signal to the kicker position in R3.
Since R3 accumulates, in principle, only one event, we fabricated high-sensitive beam diagnostic devices in the ring. They should
be applicable even for one event circulation. One of them is a cavity type of Schottky pick-up installed in a straight section of R3.
The Schottky pick-up successfully monitored a single 78 Kr36+ ion circulation with the measurement time of less than 10 ms in the firstcommissioning experiment. We also confirmed that it is useful for fine tuning of the isochronous field. Another is a timing monitor,
which detects secondary electrons emitted from thin carbon foil placed on the circulation orbit. The thickness of the foil is 50 µg/cm2 .
This timing monitor is working well to observe first several tens turns for injected event.
We performed mass measurement in the third commissioning experiment by using unstable nuclei which masses are well-known.
The masses of 79 As, 77 Ga, 76 Zn, and 75 Cu relative to 78 Ge were derived with the accuracy of less than 10 ppm. In addition, we have
improved the extraction eﬃciency to 2% by considering the matching condition between the emittance of injection events and theacceptance of R3. This extraction eﬃciency was suﬃcient to conduct the accepted two proposals: mass measurements of Ni isotopes
and mass measurements of Sn region.
In the beginning of 2018, we examined the feasibility of these two proposals in detail. Consequently, we decided to proceedwith two proposals at the same period. In the beginning of November 2018, we have conducted the first experiment using the R3 to
measure the masses for 74, 76 Ni in 4 days. After that, we also measured the masses for 122 Rh, 123, 124 Pd, and 125 Ag in 4.5 days at theend of November 2018. These nuclei were successfully extracted from R3 with the eﬃciency of 1–2%. The masses of 74, 76 Ni, 122 Rh,
and 124 Pd can be determined experimentally for the first time. On the other hand, the masses of 123 Pd and 125 Ag will be improved theprecision compared with previous experimental values. These analyses are still in progress. Since each proposal has a machine timeof several days to measure the masses of exotic nuclei, we will plan to conduct the mass measurements of the other Ni isotopes andnuclei of Sn region in 2020 or later.
With further improvements in experimental eﬃciency and mass measurement precision, the R3 enables mass measurement of
extremely rare-RIs that are inaccessible for other techniques. In 2019, we started to add one more kicker magnet. More accurate
injection and reliable extraction will be possible, the experimental eﬃciency will be improved about 10 times from the previous
experiment. We plan to conduct a beam test in 2020.

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Members
Team Leader
Masanori WAKASUGI
Research/Technical Scientist
Yoshitaka YAMAGUCHI (Technical Scientist)
Expert Technician
Takeshi MAIE
Visiting Scientists
Yasushi ABE (Nat’l Inst. of Radiological Sci.)

Fumi SUZAKI (JAEA)

List of Publications & Presentations
Publications[Original papers]
X. Xu, M. Wang, K. Blaum, J. D. Holt, Yu. A. Litvinov, A. Schwenk, J. Simonis, S. R. Stroberg, Y. H. Zhang, H. S. Xu, P. Shuai, X. L. Tu,
X. H. Zhou, F. R. Xu, G. Audi, R. J. Chen, X. C. Chen, C. Y. Fu, Z. Ge, W. J. Huang, S. Litvinov, D. W. Liu, Y. H. Lam, X. W. Ma,
R. S. Mao, A. Ozawa, B. H. Sun, Y. Sun, T. Uesaka, G. Q. Xiao, Y. M. Xing, T. Yamaguchi, Y. Yamaguchi, X. L. Yan, Q. Zeng,
H. W. Zhao, T. C. Zhao, W. Zhang, and W. L. Zhan, “Masses of neutron-rich 52–54 Sc and 54, 56 Ti nuclides: The N = 32 subshell closurein scandium,” Phys. Rev. C 99, 064303 (2019).
X. Xu, J. H. Liu, C. X. Yuan, Y. M. Xing, M. Wang, Y. H. Zhang, X. H. Zhou, Yu. A. Litvinov, K. Blaum, R. J. Chen, X. C. Chen,
C. Y. Fu, B. S. Gao, J. J. He, S. Kubono, Y. H. Lam, H. F. Li, M. L. Liu, X. W. Ma, P. Shuai, M. Si, M. Z. Sun, X. L. Tu, Q. Wang,
H. S. Xu, X. L. Yan, J. C. Yang, Y. J. Yuan, Q. Zeng, P. Zhang, X. Zhou, W. L. Zhan, S. Litvinov, G. Audi, S. Naimi, T. Uesaka,
Y. Yamaguchi, T. Yamaguchi, A. Ozawa, B. H. Sun, K. Kaneko, Y. Sun, and F. R. Xu, “Masses of ground and isomeric states of 101 In
and configuration-dependent shell evolution in odd-A indium isotopes,” Phys. Rev. C 100, 051303(R) (2019).
F. C. Ozturk, B. Akkus, D. Atanasov, H. Beyer, F. Bosch, D. Boutin, C. Brandau, P. Buehler, R. B. Cakirli, R. J. Chen, W. D. Chen,
X. C. Chen, I. Dillmann, C. Dimopoulou, W. Enders, H. G. Essel, T. Faestermann, O. Forstner, B. S. Gao, H. Geissel, R. Gernhaeuser,
R. E. Grisenti, A. Gumberidze, S. Hagmann, T. Heftrich, M. Heil, M. O. Herdrich, P. -M. Hillenbrand, T. Izumikawa, P. Kienle,
C. Klaushofer, C. Kleﬀner, C. Kozhuharov, R. K. Knoebel, O. Kovalenko, S. Kreim, T. Kuehl, C. Lederer-Woods, M. Lestinsky,
S. A. Litvinov, Yu. A. Litvinov, Z. Liu, X. W. Ma, L. Maier, B. Mei, H. Miura, I. Mukha, A. Najafi, D. Nagae, T. Nishimura,
C. Nociforo, F. Nolden, T. Ohtsubo, Y. Oktem, S. Omika, A. Ozawa, N. Petridis, J. Piotrowski, R. Reifarth, J. Rossbach, R. Sanchez,
M. S. Sanjari, C. Scheidenberger, R. S. Sidhu, H. Simon, U. Spillmann, M. Steck, Th. Stoehlker, B. H. Sun, L. A. Susam, F. Suzaki,
T. Suzuki, S. Yu. Torilov, C. Trageser, M. Trassinelli, S. Trotsenko, X. L. Tu, P. M. Walker, M. Wang, G. Weber, H. Weick, N. Winckler,
D. F. A. Winters, P. J. Woods, T. Yamaguchi, X. D. Xu, X. L. Yan, J. C. Yang, Y. J. Yuan, Y. H. Zhang, X. H. Zhou, and the FRS-ESR,
ILIMA, SPARC, and TBWD Collaborations, “New test of modulated electron capture decay of hydrogen-like 142 Pm ions: Precision
measurement of purely exponential decay,” Phys. Lett. B 797, 134800 (2019).
J. T. Zhang, K. Yue, H. X. Li, X. L. Tu, C. J. Shao, P. Ma, B. Mei, X. C. Chen, Y. Y. Yang, X. Q. Liu, Y. M. Xing, K. H. Fang, Z. Y. Sun,
M. Wang Yu. A. Litvinov, T. Yamaguchi, P. Egelhof, Y. H. Zhang, and X. H. Zhou, “The development of in-ring reaction measurements
at the HIRFL-CSR,” Nucl. Instrum. Methods Phys. Res. A 948, 162848-1–5 (2019)[Proceedings]
Z. Ge, T. Uesaka, S. Naimi, D. Nagae, Y. Abe, S. Omika, F. Suzaki, T. Yamaguchi, Y. Yamaguchi, M. Wakusugi, H. Li, K. Wakayama,
H. Arakawa, K. Inomata, K. Nishimuro, T. Kobayashi, A. Ozawa, S. Hosoi, Y. Inada, S. Suzuki, T. Moriguchi, M. Mukai, M. Amano,
D. Kamioka, and Y. Yano, “Scheme of high-resolution identification and selection of secondary Ions for mass measurements with theRare-RI Ring,” Hyper. Int. 240 92/1–11 (2019).

Presentations[International conferences/workshops]
A. Ozawa (invited), “Mass measurements for Ni-isotopes in Rare-RI Ring, RIBF,” China-Japan Collaboration Workshop on Nuclear Massand Life for Unraveling Mysteries of R-process, Beijing, China, October 10–12, 2019.
T. Yamaguchi (invited), “New experimental plan and detector R&D at the Rare-RI Ring facility,” China-Japan Collaboration Workshop
on Nuclear Mass and Life for Unraveling Mysteries of R-process, Beijing, China, October 10–12, 2019.

[Seminars]
T. Yamaguchi, “Charge changing cross section measurement—A possible method to extract point-proton radii of radioactive isotopes,”
Beihang Univ., Beijing, China, October 14, 2019.

[Domestic conferences/workshops]޲Ҫ΋΋ʢ‫ޱ‬಄ൃදʣ, ʮബບΛར༻ͨ͠ඈߦ࣌ؒ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄
17–20 ೔.
Ҵా߁ਓʢ‫ޱ‬಄ൃදʣ, ʮ‫ك‬গ RI ϦϯάͷͨΊͷϑΝΠόʔγϯνϨʔγϣϯ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

ࡉҪॣʢ‫ޱ‬಄ൃදʣ, ʮ‫ك‬গ RI ϦϯάͷͨΊബບΛར༻ͨ͠Ґஔ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬,2019 ೥ 9 ݄ 17–20 ೔.
ࢁ‫ޱ‬༝ߴʢট଴ߨԋʣ, ʮRIBF ʹ͓͚ΔॏΠΦϯ஝ੵϦϯάʯ, Ӊ஦࢙‫ڀݚ‬ηϯλʔߏ੒һձٞ, ஜ೾େֶ, ͭ͘͹, 2019 ೥ 11 ݄
21 ೔.
௕ߐେีʢ‫ޱ‬಄ൃදʣ, ʮ‫ك‬গ RI ϦϯάͰͷཻࢠ஝ੵ֬ೝͷҝͷඈߦ࣌ؒ‫ݕ‬ग़‫ث‬ʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ‫ݱ‬஍։࠵தࢭ,2020 ೥ 3 ݄ 16–19 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Instrumentation Development GroupSCRIT Team
1. Abstract

The SCRIT Electron Scattering Facility has been constructed at RIKEN RIBF. This aims at investigation of internal nuclear
structure for short-lived unstable nuclei by means of electron scattering. SCRIT (Self-Confining RI Ion Target) is a novel method
to form internal targets in an electron storage ring. This is a unique method for making electron scattering experiments for unstable
nuclei possible. Construction of the facility has been started in 2009. This facility consists of an electron accelerator (RTM), a SCRITequipped electron storage ring (SR2), an electron-beam-driven RI separator (ERIS), and a window-frame spectrometer for electron
scattering (WiSES) which consists of a large window-frame dipole magnet, drift chambers and trigger scintillators. Installationof all components in the facility was completed in 2015. After the comprehensive test and tuning, the luminosity was reached to
3 × 1027 /(cm2 s) with the number of injected ions of 3 × 108 . In 2016, we successfully completed a measurement of diﬀraction of
scattered electrons from 132 Xe nuclei and determined the charge density distribution for the first time. The facility is now under setting
up to move the first experiment for unstable nuclei.

2. Major Research Subjects

Development of SCRIT electron scattering technique and measurement of the nuclear charge density distributions of unstable
nuclei.

3. Summary of Research Activity

SCRIT is a novel technique to form internal target in an electron storage ring. Positive ions are three dimensionally confined in theelectron beam axis by transverse focusing force given by the circulating electron beam and applied electrostatic longitudinal mirror
potential. The created ion cloud composed of RI ions injected from outside works as a target for electron scattering. Constructionof the SCRIT electron scattering facility has been started in 2009. The electron accelerators RTM and the storage ring SR2 weresuccessfully commissioned in 2010. Typical accumulation current in SR2 is 250–300 mA at the energy range of 100–300 MeV that isrequired energy range in electron scattering experiment. The SCRIT device was inserted in the straight section of SR2 and connected
to an ISOL named ERIS (Electron-beam-driven RI separator for SCRIT) by 20-m long low energy ion transport line. A buncher
system based on RFQ linear trap named FRAC (Fringing-RF-field-Activated dc-to-pulse converter) was inserted in the transport line
to convert the continuous beam from ERIS to pulsed beam, which is acceptable for SCRIT. The detector system WiSES consisting ofa high-resolution magnetic spectrometer, drift chambers and trigger scintillators, was constructed, and it has a solid angle of 100 msr,
energy resolution of 10−3 , and the scattering angle coverage of 25–55 degrees. A wide range of momentum transfer, 80–300 MeV/c,
is covered by changing the electron beam energy from 150 to 300 MeV.
We successfully measured a diﬀraction pattern in the angular distribution of scattered electron from 132 Xe isotope at the electron
beam energy of 150 MeV, 200 MeV, and 300 MeV, and derived the nuclear charge distribution by assuming two-parameters Fermi
model for the first time. At this time, luminosity was reached to 3 × 1027 /(cm2 s) at maximum and the averaged value was 1.2 ×1027 /(cm2 s) with the number of injected target ions of 3 × 108 .
We are now under preparation for going to the experiments for unstable nuclei. There are some key issues for that. They are
increasing the intensity of the RI beams from ERIS, eﬃcient DC-to-pulse conversion at FRAC, improving the transmission eﬃciency
from FRAC to SCRIT, and eﬀective suppression of the background in measurement of scattered electrons. RI beam intensity will be
improved by upgrading the electron beam power from 10 W to 60 W, increasing the contained amount of U in the target ion source,and some modifications in mechanical structure in the ion source. For upgrading the electron beam power, the RF system of RTM
has been maintained intensively, and we will continue the development of RTM. For eﬃcient DC-to-pulse conversion, we establishedthe two-step bunching method, which is time compression at FRAC in combination with pre-bunching at the ion source using gridaction. Furthermore, we will improve the conversion eﬃciency and the transmission eﬃciency from FRAC to the SCRIT device bycooling the trapped ions using minuscule amounts of a buﬀer gas. These improvements on FRAC were already confirmed in oﬀ-line
test. Since one of significant contribution to the background for scattered electron is scattering from massive structural objects aroundthe trapping region originated from halo components of the electron beam, we remodeled the SCRIT electrodes. The vacuum pumpsystem at the SCRIT device has been upgraded to reduce the contribution of residual gases. Luminosity for radioactive Xe isotopes is
expected to be more than 1026 /(cm2 s) after these improvements. Then, we will be able to start experiments for unstable nuclei. Whenfurther upgrading in the RTM power planed to be 3 kW will be achieved, we can extend the measurements to more exotic nuclei.
In 2018, we developed several instruments. One is the introduction of the surface-ionization type ion source at ERIS in order
to increase kinds of radioactive beam and to produce high intensity beam. Another development is the upgrading of the drift chamber located in front of the magnetic spectrometer of WiSES to improve the momentum resolution and angular acceptance. Thesedevelopments help us to realize experiments for unstable nuclei.
In 2019, we installed a newly designed SCRIT electrodes. The main purpose of the replacement was to lower the background
during the measurement due to the electron scattering from the SCRIT electrodes itself but not from the ion targets for the experiment.
For that purpose, we employed thin metal wires to construct the electrodes rather than metal plates nor blocks. In addition, we
modified the inside structure of the SCRIT chamber to symmetrize the electric ground potential aﬀecting the potential curve inside theelectrodes. Currently, we are adjusting the SR2 accelerator and ion source ERIS to be ready for the measurement by means of the new- 317 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

SCRIT electrodes.

Members
Team Leader
Masanori WAKASUGI
Research/Technical Scientists
Masamitsu WATANABE (Senior Research Scientist)

Tetsuya OHNISHI (Senior Technical Scientist)

Expert Technician
Takeshi MAIE
Contract Researcher
Akitomo ENOKIZONO
Research Consultants
Takashi EMOTO
Masahiro HARA

Shinichi ICHIKAWA

Senior Visiting Scientist
Toshitada HORI (Hiroshima Univ.)
Visiting Scientists
Toshimi SUDA (Tohoku Univ.)
Tadaaki TAMAE (Tohoku Univ.)
Kyo TSUKADA (Tohoku Univ.)

Yuki HONDA (Tohoku Univ.)
Kazuyoshi KURITA (Rikkyo Univ.)
Shuo WANG (Shandong Univ.)

Student Trainees
Taihei AOYAGI (Tohoku Univ.)
Syota TAKAYAMA (Tohoku Univ.)

Daisuke TAKI (Tohoku Univ.)
Hikari WAUKE (Tohoku Univ.)

List of Publications & Presentations
Publications[Proceedings]
K. Tsukada, K. Adachi, A. Enokizono, T. Fujita, M. Hara, T. Hori, M. Hori, S. Ichikawa, K. Kasama, K. Kurita, K. Namba, T. Ohnishi,
T. Suda, T. Tamae, M. Togasaki, M. Wakasugi, M. Watanabe, and K. Yamada, “Electron scattering from 208 Pb and 132 Xe ions at the
SCRIT facility,” Hyperfine interact 240, 1–120 (2019).

Presentations[International conferences/workshops]
T. Suda (invited), “Proton charge radius by low-energy electron scattering,” International Workshop on the Structure of the Proton,
Yamagata, February 10–11, 2019.
T. Suda (oral), “Nuclear physics with low-energy and high-intensity electron beam,” Neutrino Nuclear Response 2019 (NNR19), RCNP,
Osaka, Japan, May 8–9, 2019.
T. Suda (invited), “Electron scattering for short-live nuclei,” Gordon Conference on “Exploring simple structural patterns and dynamics
of nuclei,” New London US, June 16–21, 2019.
T. Suda (invited), “Nuclear physics with electron beam,” Connecting Fundamental Physics, Chemistry and the Origins of Biomolecular
Homochirality, National Observatory of Japan, June 26–27, 2019.
S. Sato (oral), M. Wakasugi, T. Ohnishi, M. Watanabe, A. Enokizono, and K. Kurita, “Improvement of a dc-to-pulse conversion eﬃciency
of FRAC,” The 13th International Conference on Stopping and Manipulation of Ions and related topics (SMI2019), Montreal, Canada,
July 16–19, 2019.
T. Suda (plenary/invited), “Electron scattering for short-lived nuclei,” International Nuclear Physics Conference (INPC2019), Glasgow
UK, July 29–August 2, 2019.
M. Watanabe (poster), A. Enokizono, M. Hara, Y. Honda, T. Hori, S. Ichikawa, K. Kasama, K. Kurita, M. Nakano, K. Namba, T. Oonishi,
S. Sato, T. Suda, S. Takayama, T. Tamae, K. Tsukada, M. Wakasugi, and H. Wauke, “Fine optimization of SCRIT facility for short-lived
nuclei experiment,” International Nuclear Physics Conference (INPC2019), Glasgow, UK, July 29–August 2, 2019.
T. Suda (invited), “Proton radius,” The 11th Circum-Pan-Pacific Symposium on High Energy Spin Physics, Miyazaki Japan, August
27–30, 2019.
H. Wauke (poster), T. Aoyagi, A. Enokizono, Y. Honda, T. Suda, S. Takayama, T. Tamae, K. Tsukada, T. Ohnishi, M. Wakasugi, andM. Watanabe, “Precise magnetic field measurement of electron spectrometer for the electron scattering oﬀ unstable nuclei experiment,”
International school for Strangeness Nuclear Physics 2019, Tohoku Univ., Sendai, Japan, September 5–8, 2019.

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K. Tsukada (oral), T. Aoyagi, A. Enokizono, M. Hara, Y. Honda, T. Hori, S. Ichikawa, K. Kurita, T Ohnishi, S. Sato, T. Suda, S. Takayama,
T. Tamae, M. Wakasugi, and M. Watanabe, “Present status and future prospects of the SCRIT electron scattering facility,” 9th International Symposium on Nuclea1r Symmetry Energy (NuSYM2019), Danang City, Vietnam, September 30–October 4, 2019.
T. Suda (invited), “Proton radius,” 14th Asia-Pacific Physics Conference (APPC2019), Kuching Malaysia, November 17–22, 2019.
K. Tsukada (oral), T. Aoyagi, A. Enokizono, M. Hara, Y. Honda, T. Hori, S. Ichikawa, K. Kurita, T Ohnishi, S. Sato, T. Suda,
T. Tamae, M. Wakasugi, and M. Watanabe, “Present status of SCRIT electron scattering facility,” 14th Asia-Pacific Physics Conference(APPC2019), Sarawak, Malaysia, November 17–22, 2019.
T. Suda (invited), “Electron-scattering activities in Japan for nucleon and nuclei,” KVI Seminar, KVI Groningen, Netherlands, January 8,
2019.
T. Suda (invited), “ULQ2 project,” Collaborative Seminar by REIMEI, RCNP and Clusters, February 2020.
T. Ohnishi (oral), A. Enokizono, M. Hara, T. Hori, S. Ichikawa, K. Kurita, R. Ogawara, S. Sato, T. Suda, S. Takayama, D. Taki, S. Takagi,
T. Tamae, K. Tsukada, M. Wakasugi, M. Watanabe, and H. Wauke, “Electron scattering with unstable nuclei at the SCRIT electron
scattering facility,” Vth Topical Workshop on Modern Aspects in Nuclear Structure—The Many Facets of Nuclear Structure, Bormio,
Italy, February 4–9, (2020).

[Domestic conferences/workshops]ਢాརඒʢট଴ߨԋʣ, ʮΨϯϚઢϏʔϜΛ༻͍ͨ‫֩ࢠݪ‬ɾϋυϩϯ෺ཧͷ৽‫ہ‬໘ͱࠓ‫ޙ‬ͷల๬ʯ, ௿ΤωϧΪʔɾେిྲྀిࢠϏʔϜͱ‫֩ࢠݪ‬෺ཧ, RCNP ‫ڀݚ‬ձ, େࡕ, 2019 ೥ 3 ݄ 4–5 ೔.
ਢాརඒʢট଴ߨԋʣ, ʮཅࢠͷαΠζ͕͓͔͍͠ʁʯ, ౦‫ژ‬େֶ෺ཧֶ‫ࣨڭ‬ίϩΩ΢Ϝ, ౦‫ژ‬, 2019 ೥ 11 ݄ 8 ೔.
࿨Ӊ‫͔ͻܚ‬Γʢ‫ޱ‬಄ൃදʣ, ʮSCRIT ిࢠεϖΫτϩϝʔλʔͷ 3 ࣍‫࣓ݩ‬৔ଌఆʯ, ౦๺େֶཧֶ‫ڀݚ‬Պ 6 ઐ߈+ੜ໋Պֶ‫ڀݚ‬Պ߹ಉγϯϙδ΢Ϝ 2020, ౦๺େֶ, 2020 ೥ 2 ݄ 14 ೔.
࿨Ӊ‫͔ͻܚ‬Γʢϙελʔൃදʣ, ௩ా‫ڿ‬, ੨༄ହฏ, ਢాརඒ, ∁ࢁ঵ଠ, ୍େ༞, ‫ߐۄ‬஧໌, ຊଟ༎‫ه‬, ʮSCRIT ిࢠεϖΫτϩϝʔλʔͷ 3 ࣍‫࣓ݩ‬৔ଌఆʯ, ELPH γϯϙδ΢Ϝ, ౦๺େֶ ELPH, ઋ୆, 2019 ೥ 3 ݄ 6 ೔.
ࠤ౻૵ʢ‫ޱ‬಄ൃදʣ, ӿԂতஐ, େ੢఩໵, ‫ా܀‬࿨޷, ਢాརඒ, ௩ా‫ڿ‬, ࿨Ӊ‫͔ͻܚ‬Γ, एਿণಙ, ౉ᬑਖ਼ຬ, ʮSCRIT ࣮‫ݧ‬ͷͨΊͷߴޮ཰ RFQ Ϋʔϥʔόϯνϟʔͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
࿨Ӊ‫͔ͻܚ‬Γʢ‫ޱ‬಄ൃදʣ, ੨༄ହฏ, ӿԂতஐ, େ੢఩࠸, ‫ా܀‬࿨޷, ࠤ౻૵, ਢాརඒ, ߴ໦प, ∁ࢁ঵ଡ, ୍େ༞, ‫ߐۄ‬஧໌, ௩ా‫ڿ‬, ຊଟ༎‫ه‬, एਿণಙ, ౉ᬑਖ਼ຬ, ʮSCRIT ిࢠεϖΫτϩϝʔλʔͷ 3 ࣍‫࣓ݩ‬৔ଌఆʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
௩ా‫ڿ‬ʢ‫ޱ‬಄ൃදʣ, ੨༄ଠฏ, ࢢ઒ਐҰ, ӿԂতஐ, େ੢఩࠸, ‫ా܀‬࿨޷, ࠤ౻૵, ਢాརඒ, ߴࢁ঵ଡ, ୍େ༞, ‫ߐۄ‬஧໌, ‫ݪ‬խ߂, ງར‫ڡ‬, ຊଟ༎‫ه‬, ࿨Ӊ‫͔ͻܚ‬Γ, एਿণಙ, ౉ᬑਖ਼ຬ, ʮ୸ૉඪతΛ༻͍ͨ SCRIT ࣮‫ࢠి༻ݧ‬εϖΫτϩϝʔλͷੑೳධՁʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.

[International seminars/lectures]
T. Suda, Lectures: “Electron scattering for nucleon and nuclei,” Johannesburg, South Africa, October 19–November 3, 2019.
T. Suda, Public lecture: “Nihonium: 113th element,” Johannesburg, South Africa, October 19–November 3, 2019.

[Domestic seminars/lectures]ਢాརඒ, ʮిࢠઢ֩෺ཧಛ࿦ʯ, େֶӃߨٛ, 2019 ೥ 10 ݄–2020 ೥ 3 ݄.
ਢాརඒ, ʮӉ஦૑ੜ෺ཧֶ֓࿦ʯ, GPPU ߨٛ, 2019 ೥ 6 ݄.
ਢాརඒ, ʮ‫ݩ‬ૉʹ͍ͭͯʯ, ‫۽‬୩ߴߍ๚໰ੜ΁ͷಛผߨٛ, 2019 ೥ 8 ݄ 26 ೔.
ਢాརඒ, “Physics Today,” ৽ׁେֶूதߨٛ, 2019 ೥ 12 ݄ 3–5 ೔.
ਢాརඒ, ʮ‫ݩ‬ૉͱ‫֩ࢠݪ‬ʯ, ‫۽‬୩ߴߍಛผत‫ۀ‬, 2019 ೥ 12 ݄ 6 ೔.
ਢాརඒ, ʮ೔ຊͰൃ‫͞ݟ‬Εͨ 113 ൪৽‫ݩ‬ૉχϗχ΢Ϝʯ, ઋ୆੨ྕத౳ֶߍग़લत‫ۀ‬, 2019 ೥ 12 ݄ 10 ೔.

AwardsH. Wauke, SNP School Incentive Prize, “Precise magnetic field measurement of electron spectrometer for the electron scattering oﬀ
unstable nuclei experiment,” International school for Strangeness Nuclear Physics 2019, Tohoku Univ., Sendai, Japan, September 5–8,
2019.

Others
T. Ohnishi, A. Enokizono, M. Hara, T. Hori, S. Ichikawa, K. Kurita, R. Ogawara, S. Sato, T. Suda, S. Takayama, D. Taki, S. Takagi,
T. Tamae, K. Tsukada, M. Wakasugi, M. Watanabe, and H. Wauke, “The SCRIT project at RIKEN,” NUSTAR Annual Meeting 2020,
GSI, Darmstadt, Germany, March 2–6, (2020).

- 319 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Research Instruments Group
1. Abstract
The Research Instruments Group is the driving force at RI Beam Factory (RIBF) for continuous enhancement of activities andcompetitiveness of experimental research. Consisting of four teams, we are in charge of the operation, maintenance, and improvementof the core research instruments at RIBF, such as the BigRIPS in-flight RI separator, ZeroDegree spectrometer and SAMURAI spectrometer, and the related infrastructure and equipment. We are also in charge of the production and delivery of RI beams using the
BigRIPS separator. The group also conducts related experimental research as well as R&D studies on the research instruments.

2. Major Research Subjects
Design, construction, operation, maintenance, and improvement of the core research instruments at RIBF and related R&D studies.
Experimental studies on exotic nuclei.

3. Summary of Research Activity
The current research subjects are summarized as follows:(1) Production and delivery of RI beams and related research(2) Design, construction, operation, maintenance, and improvement of the core research instruments at RIBF and their related
infrastructure and equipment(3) R&D studies on the core research instruments and their related equipment at RIBF
(4) Experimental research on exotic nuclei using the core research instruments at RIBF

Members
Director
Tomohiro UESAKA
Contract Researcher
Toshiyuki KUBO
Junior Research Associate
Rieko TSUNODA
Senior Visiting Scientist
Toshio KOBAYASHI (Tohoku Univ.)
Student Trainee
Fumitaka ENDO (Tohoku Univ.)- 320 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Research Instruments GroupBigRIPS Team
1. Abstract
This team is in charge of design, construction, development and operation of BigRIPS in-flight separator and its related research
instruments at RI beam factory (RIBF). They are employed not only for the production of RI beams but also the experimental studies
using RI beams.

2. Major Research Subjects
Design, construction, development and operation of BigRIPS in-flight separator, RI-beam transport lines, and their related research
instruments

3. Summary of Research Activity
This team is in charge of design, construction, development and operation of BigRIPS in-flight separator, RI-beam transport lines,
and their related research instruments such as ZeroDegree spectrometer at RI beam factory (RIBF). They are employed not only forthe production of RI beams but also various kinds of experimental studies using RI beams. The research subjects may be summarized
as follows:(1) General studies on RI-beam production using in-flight scheme.
(2) Studies on ion-optics of in-flight separators, including particle identification of RI beams.
(3) Simulation and optimization of RI-beam production.
(4) Development of beam-line detectors and their data acquisition system.
(5) Experimental studies on production reactions and unstable nuclei.
(6) Experimental studies of the limits of nuclear binding.
(7) Development of superconducting magnets and their helium cryogenic systems.
(8) Development of a high-power production target system.
(9) Development of a high-power beam dump system.
(10) Development of a remote maintenance and remote handling systems.
(11) Operation, maintenance and improvement of BigRIPS separator system, RI-beam transport lines, and their related research
instruments such as ZeroDegree spectrometer and so on.
(12) Experimental research using RI beams.

Members
Team Leader
Koichi YOSHIDA
Research/Technical Scientists
Yoshiyuki YANAGISAWA (Senior Research Scientist)
Naohito INABE (Senior Technical Scientist)
Kensuke KUSAKA (Senior Technical Scientist)

Masao OHTAKE (Senior Technical Scientist)
Naoki FUKUDA (Technical Scientist)
Hiroyuki TAKEDA (Technical Scientist)

Contract Researchers
Deuk Soon AHN
Yohei SHIMIZU

Hiroshi SUZUKI

Visiting Scientists
Alan Matthew AMTHOR (Bucknell Univ.)
Daniel P. BAZIN (Michigan State Univ.)
Alfredo ESTRADE VAZ (Central Michigan Univ.)
Michael FAMIANO (Western Michigan State Univ.)
Hans GEISSEL (GSI/Justus-Liebig Univ. Giessen)
Tuomas Arne Santeri GRAHN (Univ. of Jyvaskyla)
Kazuo IEKI (Rikkyo Univ.)

Naohito IWASA (Tohoku Univ.)
Yutaka MIZOI (Univ. of Electro-Commun.)David MORRISSEY (Michigan State Univ.)
Mauricio PORTILLO (Michigan State Univ.)
Bradley M. SHERRILL (Michigan State Univ.)
Oleg TARASOV (Michigan State Univ.)

Student Trainee
Shunki ISHIKAWA (Tohoku Univ.)- 321 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Part-time Worker
Tetsuro KOMATSUBARA (Research Part-time Worker I)

List of Publications & Presentations
Publications[Original papers]
Y. Ichikawa, H. Nishibata, Y. Tsunoda, A. Takamine, K. Imamura, T. Fujita, T. Sato, S. Momiyama, Y. Shimizu, D. S. Ahn, K. Asahi,
H. Baba, D. L. Balabanski, F. Boulay, J. M. Daugas, T. Egami, N. Fukuda, C. Funayama, T. Furukawa, G. Georgiev, A. Gladkov,
N. Inabe, Y. Ishibashi, T. Kawaguchi, T. Kawamura, Y. Kobayashi, S. Kojima, A. Kusoglu, I. Mukul, M. Niikura, T. Nishizaka,
A. Odahara, Y. Ohtomo, T. Otsuka, D. Ralet, G. S. Simpson, T. Sumikama, H. Suzuki, H. Takeda, L. C. Tao, Y. Togano, D. Tominaga,
H. Ueno, H. Yamazaki, and X. F. Yang, “Interplay between nuclear shell evolution and shape deformation revealed by the magnetic
moment of 75 Cu,” Nat. Phys. 15, 321 (2019).
Z. Q. Chen, Z. H. Li, H. Hua, H. Watanabe, C. X. Yuan, S. Q. Zhang, G. Lorusso, S. Nishimura, H. Baba, F. Browne, G. Benzoni,
K. Y. Chae, F. C. L. Crespi, P. Doornenbal, N. Fukuda, G. Gey, R. Gernhäuser, N. Inabe, T. Isobe, D. X. Jiang, A. Jungclaus, H. S. Jung,
Y. Jin, D. Kameda, G. D. Kim, Y. K. Kim, I. Kojouharov, F. G. Kondev, T. Kubo, N. Kurz, Y. K. Kwon, X. Q. Li, J. L. Lou, G. J. Lane,
C. G. Li, D. W. Luo, A. Montaner-Pizá, K. Moschner, C. Y. Niu, F. Naqvi, M. Niikura, H. Nishibata, A. Odahara, R. Orlandi, Z. Patel,
Zs. Podolyák, T. Sumikama, P. -A. Söderström, H. Sakurai, H. Schaﬀner, G. S. Simpson, K. Steiger, H. Suzuki, J. Taprogge, H. Takeda,
Zs. Vajta, H. K. Wang, J. Wu, A. Wendt, C. G. Wang, H. Y. Wu, X. Wang, C. G. Wu, C. Xu, Z. Y. Xu, A. Yagi, Y. L. Ye, andK. Yoshinaga, “Proton shell evolution below 132 Sn: first measurement of low-lying β-emitting isomers in 123, 125 Ag,” Phys. Rev. Lett.
122, 212502 (2019).
D. Lubos, J. Park, T. Faestermann, R. Gernhäuser, R. Krücken, M. Lewitowicz, S. Nishimura, H. Sakurai, D. S. Ahn, H. Baba, B. Blank,
A. Blazhev, P. Boutachkov, F. Browne, I. Čeliković, G. de France, P. Doornenbal, Y. Fang, N. Fukuda, J. Giovinazzo, N. Goel,
M. Górska, S. Ilieva, N. Inabe, T. Isobe, A. Jungclaus, D. Kameda, Y. K. Kim, I. Kojouharov, T. Kubo, N. Kurz, Y. K. Kwon, G. Lorusso,
K. Moschner, D. Murai, I. Nishizuka, Z. Patel, M. M. Rajabali, S. Rice, H. Schaﬀner, Y. Shimizu, L. Sinclair, P. -A. Söderström,
K. Steiger, T. Sumikama, H. Suzuki, H. Takeda, Z. Wang, N. Warr, H. Watanabe, J. Wu, and Z. Xu, “Improved value for the gamowteller strength of the 100 Sn beta decay,” Phys. Rev. Lett. 122, 222502 (2019).
D. S. Ahn, N. Fukuda, H. Geissel, N. Inabe, N. Iwasa, T. Kubo, K. Kusaka, D. J. Morrissey, D. Murai, T. Nakamura, M. Ohtake, H. Otsu,
H. Sato, B. M. Sherrill, Y. Shimizu, H. Suzuki, H. Takeda, O. B. Tarasov, H. Ueno, Y. Yanagisawa, and K. Yoshida, “Location of theneutron dripline at fluorine and neon,” Phys. Rev. Lett. 123, 212501 (2019).
H. Watanabe, H. K. Wang, G. Lorusso, S. Nishimura, Z. Y. Xu, T. Sumikama, P. -A. Söderström, P. Doornenbal, F. Browne, G. Gey,
H. S. Jung, J. Taprogge, Zs. Vajta, J. Wu, A. Yagi, H. Baba, G. Benzoni, K. Y. Chae, F. C. L. Crespi, N. Fukuda, R. Gernhäuser,
N. Inabe, T. Isobe, A. Jungclaus, D. Kameda, G. D. Kim, Y. K. Kim, I. Kojouharov, F. G. Kondev, T. Kubo, N. Kurz, Y. K. Kwon,
G. J. Lane, Z. Li, C. -B. Moon, A. Montaner-Pizá, K. Moschner, F. Naqvi, M. Niikura, H. Nishibata, D. Nishimura, A. Odahara,
R. Orlandi, Z. Patel, Zs. Podolyák, H. Sakurai, H. Schaﬀner, G. S. Simpson, K. Steiger, Y. Sun, H. Suzuki, H. Takeda, A. Wendt,
and K. Yoshinaga, “New isomers in 125 Pd79 and 127 Pd81 : Competing proton and neutron excitations in neutron-rich palladium nuclides
towards the N = 82 shell closure,” Phys. Lett. B 792, 263 (2019).
A. Corsi, Y. Kubota, J. Casal, M. Gómez-Ramos, A. M. Moro, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono,
J. Feng, F. Flavigny, J. -M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim,
Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F. M. Marqués,
T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, N. A. Orr, S. Ota, H. Otsu, T. Ozaki,
V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. -Y. Rousse, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano,
H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y. L. Sun, M. Tabata, Y. Togano, J. Tsubota, T. Uesaka, Z. H. Yang,
J. Yasuda, K. Yoneda, and J. Zenihiro, “Structure of 13 Be probed via quasi-free scattering,” Phys. Lett. B 797, 134843 (2019).
G. X. Zhang, H. Watanabe, G. D. Dracoulis, F G. Kondev, G. J. Lane, P. H. Regan, P. -A. Söderström, P. M. Walker, K. Yoshida,
H. Kanaoka, Z. Korkulu, P. S. Lee, J. J. Liu, S. Nishimura, J. Wu, A. Yagi, D. S. Ahn, T. Alharbi, H. Baba, F. Browne, A. M. Bruce,
M. P. Carpenter, R. J. Carroll, K. Y. Chae, C. J. Chiara, Zs. Dombradi, P. Doornenbal, A. Estrade, N. Fukuda, C. Griﬃn, E. Ideguchi,
N. Inabe, T. Isobe, S. Kanaya, I. Kojouharov, T. Kubo, S. Kubono, N. Kurz, I. Kuti, S. Lalkovski, T Lauritsen, C. S. Lee, E. J. Lee,
C. J. Lister, G. Lorusso, G. Lotay, E. A. McCutchan, C. -B. Moon, I. Nishizuka, C. R. Nita, A. Odahara, Z. Patel, V. H. Phong,Zs. Podolyák, O. J. Roberts, H. Sakurai, H. Schaﬀner, D. Seweryniak, C. M. Shand, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda,
S. Terashima, Zs. Vajta, J. J. Valiente-Dóbon, Z. Y. Xu, and S. Zhu, “Interplay of quasiparticle and vibrational excitations: First
observation of isomeric states in 168 Dy and 169 Dy,” Phys. Lett. B 799, 135036 (2019).
P. J. Davies, J. Park, H. Grawe, R. Wadsworth, R. Gernhäuser, R. Krücken, F. Nowacki, D. S. Ahn, F. Ameil, H. Baba, T. Bäck, B. Blank,
A. Blazhev, P. Boutachkov, F. Browne, I. Cěliković, M. Dewald, P. Doornenbal, T. Faestermann, Y. Fang, G. de France, N. Fukuda,
A. Gengelbach, J. Gerl, J. Giovinazzo, S. Go, N. Goel, M. Górska, E. Gregor, H. Hotaka, S. Ilieva, N. Inabe, T. Isobe, D. G. Jenkins,
J. Jolie, H. S. Jung, A. Jungclaus, D. Kameda, G. D. Kim, Y. -K. Kim, I. Kojouharov, T. Kubo, N. Kurz, M. Lewitowicz, G. Lorusso,
D. Lubos, L. Maier, E. Merchan, K. Moschner, D. Murai, F. Naqvi, H. Nishibata, D. Nishimura, S. Nishimura, I. Nishizuka, Z. Patel,
N. Pietralla, M. M. Rajabali, S. Rice, H. Sakurai, H. Schaﬀner, Y. Shimizu, L. F. Sinclair, P. -A. Söderström, K. Steiger, T. Sumikama,
H. Suzuki, H. Takeda, J. Taprogge, P. Thöle, S. Valder, Z. Wang, N. Warr, H. Watanabe, V. Werner, J. Wu, Z. Y. Xu, A. Yagi,
K. Yoshinaga, and Y. Zhu, “Toward the limit of nuclear binding on the N = Z line: Spectroscopy of 96 Cd,” Phys. Rev. C 99, 021302(R)(2019).
J. Park, R. Krücken, D. Lubos, R. Gernhäuser, M. Lewitowicz, S. Nishimura, D. S. Ahn, H. Baba, B. Blank, A. Blazhev, P. Boutachkov,
F. Browne, I. Čeliković, G. de France, P. Doornenbal, T. Faestermann, Y. Fang, N. Fukuda, J. Giovinazzo, N. Goel, M. Górska,- 322 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

H. Grawe, S. Ilieva, N. Inabe, T. Isobe, A. Jungclaus, D. Kameda, G. D. Kim, Y. -K. Kim, I. Kojouharov, T. Kubo, N. Kurz, Y. K. Kwon,
G. Lorusso, K. Moschner, D. Murai, I. Nishizuka, Z. Pate, M. M. Rajabali, S. Rice, H. Sakurai, H. Schaﬀner, Y. Shimizu, L. Sinclair,
P. -A. Söderström, K. Steiger, T. Sumikama, H. Suzuki, H. Takeda, Z. Wang, H. Watanabe, and J. Wu, “New and comprehensive β- andβp-decay spectroscopy results in the vicinity of 100 Sn,” Phys. Rev. C 99, 034313 (2019).
V. H. Phong, G Lorusso, T. Davinson, A. Estrade, O. Hall, J. Liu, K. Matsui, F. Montes, S. Nishimura, A. Boso, P. H. Regan, R. Shearman,
Z. Y. Xu, J. Agramunt, J. M. Allmond, D. S. Ahn, A. Algora, H. Baba, N. T. Brewer, C. G. Bruno, R. Caballero-Folch, F. Calvino,
M. Wolińska-Cichocka, G. Cortes, I. Dillmann, C. Domingo-Pardo, A. Gargano, S. Go, C. J. Griﬃn, R. K. Grzywacz, L. HarknessBrennan, T. Isobe, A. Jungclaus, D. Kahl, L. H. Khiem, G. Kiss, A. Korgul, S. Kubono, K. Miernik, A. I. Morales, N. Nepal, M. Piersa,
Zs. Podolyák, B. C. Rasco, K. P. Rykaczewski, H. Sakurai, Y. Shimizu, D. W. Stacener, T. Sumikama, H. Suzuki, H. Takeda, J. L. Tain,
A. Tarifeño-Saldivia, A. Tolosa-Delgado, V. Vaquero, P. J. Woods, R. Yokoyama, and C. Yuan, “Observation of a µs isomer in 134
49 In85 :Proton-neutron coupling “southeast” of 132
50 Sn82 ,” Phys. Rev. C 100, 011302(R) (2019).
R. Yokoyama, R. Grzywacz, B. C. Rasco, N. Brewer, K. P. Rykaczewski, I. Dillmann, J. L. Tain, S. Nishimura, D. S. Ahn, A. Algora,
J. M. Allmond, J. Agramunt, H. Baba, S. Bae, C. G. Bruno, R. Caballero-Folch, F. Calvino, P. J. Coleman-Smith, G. Cortes, T. Davinson, C. Domingo-Pardo, A. Estrade, N. Fukuda, S. Go, C. J. Griﬃn, J. Ha, O. Hall, L. J. Harkness-Brennan, J. Heideman, T Isobe,
D. Kahl, M. Karny, T. Kawano, L. H. Khiem, T. T. King, G. G. Kiss, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, J. Liang, J. Liu,
G. Lorusso, M. Madurga, K. Matsui, K. Miernik, F. Montes, A. I. Morales, P. Morrall, N. Nepal, R. D. Page, V. H. Phong, M. Piersa,
M. Prydderch, V. F. E. Pucknell, M. M. Rajabali, B. Rubio, Y. Saito, H. Sakurai, Y. Shimizu, J. Simpson, M. Singh, D. W. Stracener,
T. Sumikama, R. Surman, H. Suzuki, H. Takeda, A. Tarifeño-Saldivia, S L. Thomas, A. Tolosa-Delgado, M. Wolińska-Cichocka,
P. J. Woods, and X. X. Xu “Strong one-neutron emission from two-neutron unbound states in β decays of the r-process nuclei 86, 87 Ga,”
Phys. Rev. C 100, 031302(R) (2019).
L. Sinclair, R. Wadsworth, J. Dobaczewski, A. Pastore, G. Lorusso, H. Suzuki, D. S. Ahn, H. Baba, F. Browne, P. J. Davies, P. Doornenbal,
A. Estrade, Y. Fang, N. Fukuda, J. Henderson, T. Isobe, D. G. Jenkins, S. Kubono, Z. Li, D. Lubos, S. Nishimura, I. Nishizuka, Z. Patel,
S. Rice, H. Sakurai, Y. Shimizu, P. Schury, H. Takeda, P. -A. Söderström, T. Sumikama, H. Watanabe, V. Werner, J. Wu, and Z. Y. Xu,“Half-lives of 73 Sr and 76Y and the consequences for the proton dripline,” Phys. Rev. C 100, 044311 (2019).
K. Nakano, Y. Watanabe, S. Kawase, H. Wang, H. Otsu, H. Sakurai, S. Takeuchi, Y. Togano, T. Nakamura, Y. Maeda, D. S. Ahn,
M. Aikawa, S. Araki, S. Chen, N. Chiga, P. Doornenbal, N. Fukuda, T. Ichihara, T. Isobe, S. Kawakami, T. Kin, Y. Kondo, S. Koyama,
T. Kubo, S. Kubono, M. Uesaka, A. Makinaga, M. Matsushita, T. Matsuzaki, S. Michimasa, S. Momiyama, S. Nagamine, M. Niikura,T. Ozaki, A. Saito, T. Saito, Y. Shiga, M. Shikata, Y. Shimizu, S. Shimoura, T. Sumikama, P. A. Söderström, H. Suzuki, H. Takeda,
R. Taniuchi, J. Tsubota, Y. Watanabe, K. Wimmer, T. Yamamoto, and K. Yoshida, “Isotope production in proton-, deuteron-, andcarbon-induced reactions on 93 Nb at 113 MeV/nucleon” Phys. Rev. C 100, 044605 (2019).
H. Wang, H. Otsu, N. Chiga, S. Kawase, S. Takeuchi, T. Sumikama, S. Koyama, H. Sakurai, Y. Watanabe, S. Nakayama, D. S. Ahn,
H. Baba, S. D. Chen, K. Chikaato, M. L. Cortés, N. Fukuda, A. Hirayama, R. Hosoda, T. Isobe, S. Kawakami, Y. Kondo, S. Kubono,
Y. Maeda, S. Masuoka, S. Michimasa, I. Murray, R. Nakajima, T. Nakamura, K. Nakano, M. Nishimura, T. Ozaki, A. Saito, T. Saito,
H. Sato, Y. Shimizu, S. Shimoura, P. -A. Söderström, Y. Soudo, X. H. Sun, J. Suwa, D. Suzuki, H. Suzuki, H. Takeda, M. Takechi,
Y. Togano, T. Tomai, H. Yamada, M. Yasuda, and K. Yoshida, “Enhancement of element production by incomplete fusion reaction withweakly bound deuteron,” Commun. Phys. 2, 78 (2019).
A. Tolosa-Delgado, J. Agramunt, J. L. Tain, A. Algora, C. Domingo-Pardo, A. I. Morales, B. Rubio, A. Tarifeno-Saldivia, F. Calvino,
G. Cortes, N. T. Brewer, B. C. Rasco, K. P. Rykaczewski, D. W. Stracener, J. M. Allmond, R. Grzywacz, R. Yokoyama, M. Singh,
T. King, M. Madurga, S. Nishimura, V. H. Phong, S. Go, J. Liu, K. Matsui, H. Sakurai, G. G. Kiss, T. Isobe, H. Baba, S. Kubono,
N. Fukuda, D. S. Ahn, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda, P. A. Soderstrom, M. Takechi, C. G. Bruno, T. Davinson,
C. J. Griﬃn, O. Hall, D. Kahl, P. J. Woods, P. J. Coleman-Smith, M. Labiche, I. Lazarus, P. Morrall, V. F. E. Pucknell, J. Simpson,
S. L. Thomas, M. Prydderch, L. J. Harkness-Brennan, R. D. Page, I. Dillmann, R. Caballero-Folch, Y. Saito, A. Estrade, N. Nepal,
F. Montes, G. Lorusso, J. Liang, S. Bae, J. Ha, B. Moon, the BRIKEN collaboration, “Commissioning of the BRIKEN detector for themeasurement of very exoticβ-delayed neutron emitters,” Nucl. Instrum. Methods Phys. Res. A 925, 133 (2019).
S. Takeuchi, T. Nakamura, M. Shikata, Y. Togano, Y. Kondo, J. Tsubota, T. Ozaki, A. Saito, H. Otsu, H. Wang, H. Sakurai, Y. Watanabe,
S. Kawase, D. S. Ahn, M. Aikawa, T. Ando, S. Araki, S. Chen, N. Chiga, P. Doornenbal, S. Ebata, N. Fukuda, T. Isobe, S. Kawakami,
T. Kin, S. Koyama, S. Kubono, Y. Maeda, A. Makinaga, M. Matsushita, T. Matsuzaki, S. Michimasa, S. Momiyama, S. Nagamine,
K. Nakano, M. Niikura, K. Ogata, T. Saito, Y. Shiga, Y. Shimizu, S. Shimoura, T. Sumikama, Pär-Anders Söderstrom, H. Suzuki,
H. Takeda, R. Taniuchi, M. Uesaka, Y. Watanabe, K. Wimmer, T. Yamamoto, and K. Yoshida, “Coulomb breakup reactions of 93, 94 Zr
in inverse kinematics,” Prog. Theor. Exp. Phys. 2019, 013D02 (2019).
S. Michimasa, J. Hwang, K. Yamada, S. Ota, M. Dozono, N. Imai, K. Yoshida, Y. Yanagisawa, K. Kusaka, M. Ohtake, M. Matsushita,
D. S. Ahn, O. Beliuskina, N. Chiga, K. Chikaato, N. Fukuda, S. Hayakawa, E. Ideguchi, K. Iribe, C. Iwamoto, S. Kawase, K. Kawata,
N. Kitamura, S. Masuoka, H. Miyatake, D. Nagae, R. Nakajima, T. Nakamura, K. Nakano, S. Omika, H. Otsu, H. Sakurai, P. Schrock,H. Shimizu, Y. Shimizu, T. Sumikama, X. Sun, D. Suzuki, H. Suzuki, M. Takaki, M. Takechi, H. Takeda, S. Takeuchi, T. Teranishi,
R. Tsunoda, H. Wang, Y. Watanabe, Y. X. Watanabe, K. Wimmer, K. Yako, H. Yamaguchi, L. Yang, H. Yoshida, and S. Shimoura,“OEDO, the energy-degrading beamline at RI Beam Factory,” Prog. Theor. Exp. Phys. 2019, 043D01 (2019).
J. Hwang, S. Michimasa, S. Ota, M. Dozono, N. Imai, K. Yoshida, Y. Yanagisawa, K. Kusaka, M. Ohtake, D. S. Ahn, O. Beliuskina,
N. Fukuda, C. Iwamoto, S. Kawase, K. Kawata, N. Kitamura, S. Masuoka, H. Otsu, H. Sakurai, P. Schrock, T. Sumikama, H. Suzuki,
M. Takaki, H. Takeda, R. Tsunoda, K. Wimmer, K. Yako, and S. Shimoura, “Angle-tunable wedge degrader for an energy-degrading
RI beamline “, Prog. Theor. Exp. Phys. 2019, 043D02 (2019).
T. Sonoda, I. Katayama, M. Wada, H. Iimura, V. Sonnenschein, S. Iimura, A. Takamine, M. Rosenbusch, T. M. Kojima, D. S. Ahn,
N. Fukuda, T. Kubo, S. Nishimura, Y. Shimizu, H. Suzuki, H. Takeda, M. Tanigaki, H. Tomita, K. Yoshida, and H. Ishiyama, “Conceptual study on parasitic low-energy RI beam production with in-flight separator BigRIPS and the first stopping examination for
high-energy RI beams in the parasitic gas cell,” Prog. Theor. Exp. Phys. 2019, 113D02 (2019).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53[Proceedings]
K. Kusaka, “Long term operation of the superconducting triplet quadrupoles with cryocoolers for BigRIPS in-flight separator at RIKEN,”
2019 IOP Conf. Ser.: Mater. Sci. Eng. 502, 012103(2019).

Presentations[International conferences/workshops]
H. Suzuki (oral), “Discovery of 72 Rb & production of proton-rich RI-beams at RIBF,” The International Conference on Proton-Emitting
nuclei (PROCON2019), East Lansing, Michigan, USA, June 3–7, 2019.
N. Fukuda (invited), “Observation of new isotopes at RIKEN RI Beam Factory,” XXXVI Mazurian Lakes Conference on Physics, Piaski,
Poland, September 1–7, 2019.
K. Kusaka (poster), “Long term operation of the superconducting triplet quadrupoles with cryocoolers,” EUCAS2019: 14th European
Conference on Applied Superconductivity, SEC, Glasgow, UK, September 1–5, 2019.
D. S. Ahn (invited), “Status of RI beam production at BigRIPS,” Expert meeting on Next-Generation Fragment Separators 2019, Darmstadt, Germany, September 30–October 2, 2019.
H. Takeda(invited), “Development of various new ion-optics modes at BigRIPS,” Expert meeting on Next-Generation Fragment Separators
2019, Darmstadt, Germany, September 30–October 2, 2019.
N. Fukuda (invited), “Observation of new isotopes at RIKEN RI Beam Factory,” 14th Asia Pacific Physics Conference, Sarawak, Malaysia,
November 17–21, 2019.
N. Fukuda (oral), “Present status of RI production at RIKEN RI Beam Factory and future prospects—RI Production at high energies—,”
JSPS/NRF/NSFC A3 Foresight Program “Nuclear Physics in the 21st Century,” Joint Kickoﬀ Meeting, Kobe, Japan, December 6–7,
2019.

[Domestic conferences/workshops]দຊᠳଡʢ‫ޱ‬಄ൃදʣ, ੢ོത, ߴ໦‫ج‬৳, A. D. Soon, അ৔ल஧, ౻Ԭ޺೭, ෱ా௚थ, ෱੢ெঘ, H. Geissel, Ҵลঘਓ, ൘‫݈ڮ‬ଠ, ೔Լ݈༞, ࡾ໦‫ݠ‬ೋ࿠, ࡾྠւ࠼, Ӭߐ஌จ, ࡕ্गԻ, ਗ਼ਫཅฏ, ୸‫ה‬૱೭, ླ໦޺, ஛ాߒ೭, ాதྑथ, ্ࡔ༑༸, ౉ลचҎ, ໼޲‫ݠ‬ଠ࿠, ༄ᖒળߦ, ٢ాޫҰ, મኍेࡾ, ʮBigRIPS ʹ͓͚Δߴਫ਼౓ύΠதؒࢠ‫ࢠݪ‬෼ޫɾೋॏΨϞϑʵςϥʔ‫ڊ‬େ‫ڞ‬໐୳ࡧ࣮‫ݧ‬ͷ‫ݱ‬ঢ়ʯ, ೔ຊ෺ཧֶձୈ 72 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
S. Masuoka, S. Shimoura, M. Takaki, M. Dozono, C. Iwamoto, K. Kawata, N. Kitamura, M. Kobayashi, S. Michimasa, R. Nakajima,
S. Ota, H. Tokieda, R. Yokoyama, D. S. Ahn, H. Baba, N. Fukuda, T. Harada, E. Ideguchi, N. Imai, N. Inabe, Y. Kondo, T. Kubo,
Y. Maeda, F. M. Marques, M. Matsushita, T. Nakamura, N. Orr, H. Sakai, H. Sato, P. Schrock, L. Stuhl, T. Sumikama, H. Suzuki,
H. Takeda, K. Taniue, T. Uesaka, K. Wimmer, K. Yako, Y. Yamaguchi, Y. Yanagisawa, K. Yoshida, and J. Zenihiro, ʮೋॏՙిަ‫׵‬൓
Ԡ 4 He(8 He, 8 Be) ൓Ԡͷ࠶ଌఆ IIʯ, ೔ຊ෺ཧֶձୈ 72 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
ࡾ໦੖ྤ, தଜོ࢘ (‫ޱ‬಄ൃද), ۙ౻༸հ, N. L. Achouri, T. Aumann, അ৔ल஧, F. Delaunay, P. Doornenbal, ෱ా௚थ, J. Gibelin,
J. Hwang, Ҵลঘਓ, ү෦஧ত, ُాେี, ؆໺େً, S. Kim, খྛ৴೭, খྛढ़༤, ‫ٱ‬อහ޾, S. Leblond, J. Lee, M. Marques, ೆํ྄‫ޗ‬, ຊྛಁ, ଜҪେ஍, ଜ্఩໵, ෢౻‫ۏ‬ඒ, தౢৎՅ, த௩ಙ‫ܧ‬, A. Navin, ੢੐࣐࿠, ੜӽॣ, N. A. Orr, େ௡ल‫ڿ‬, ࠤ౻޿ւ, ࠤ౻ًٛ, ਗ਼ਫཅฏ, ླ໦޺, ߴ‫ݡڮ‬ਓ, ஛ాߒ೭, ෢಺૱, ాதོ‫ݾ‬, ௪໺ହ޺, A. G. Tuﬀ, M. Vandebrouck, ถా݈Ұ࿠, ʮՙిަ‫׵‬൓ԠΛ༻͍ͨதੑࢠա৒ඇଋറ֩ 28 F ͷ‫ڀݚ‬ʯ, ೔ຊ෺ཧֶձୈ 72 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
෌ాਸ਼थ (‫ޱ‬಄ൃද), ෢ஐຑ໹, େ௶ོ, ຊؒজ, ాத੟ਉ, ෱ాޫॱ, ླ໦݈, ੢ଜଠथ, ৿‫ޱ‬఩࿕, ҆ಘॱ, A. S. Aimaganbetov, ఱ໺কಓ, ߥ઒༟थ, S. Bagchi, K. H. Behr, N. Burtebayev, ਌੻࿨໻, ైߤ, ౻Ҫ๎໵, ෱ా௚थ, H. Geissel, ງଠ஍, ੕໺णय़, ҏ‫ޒ‬ᖒྋ, ஑ా࠼Ն, Ҵลঘਓ, ழ‫ۢވ‬ඒ, ൘‫݈ڮ‬ଠ, ઘ઒୎࢘, ্Ԭେ‫ى‬, ਆా௚ਓ, Ճ౻Үຏ, I. Kenzhina, Z. Korkulu, Ye. Kuk, ೔Լ݈༞, ࡾ‫࢚جݪ‬, ‫ܙాٶ‬ཧ, ௕ߐେี, தଜᠳ݈, M. Nassurlla, ੢ࣨࠃޫ, ੢௩‫࣏ݡ‬, େᙈॢҰ࿕, େ੢߁հ, େ஛੓༤, Ԧ‫ܙ‬ਔ, খ୔‫ݦ‬, A. Prochazka, ᓎҪതّ, C. Scheidenberger, ਗ਼ਫཅฏ, ਿ‫وݪ‬৴, ୸‫ה‬૱೭, ླ໦৳࢘, ླ໦޺, ஛ాߒ೭, ాத༔ଠ࿠, ాதྑथ,࿨ాଠ࿠, एࢁਗ਼ࢤ, ീ໦ᠳҰ, ࢁ‫وޱ‬೭, ༄‫ే཮ݪ‬, ༄ᖒળߦ, ٢ాޫҰ, T. K. Zholdybayev, ʮSc ಉҐମͷՙిมԽஅ໘ੵଌఆʯ,೔ຊ෺ཧֶձୈ 72 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
ಊԂণഢ (‫ޱ‬಄ൃද), ࠓҪ৳໌, ಓਖ਼৽Ұ࿠, ԼӜ‫ڗ‬, େా৾ี, ୸‫ה‬૱೭, ઍլ৴޾, େ௡ल‫ڿ‬, ೖ෦߂ଠ࿠, ଞ ImPACT17-02-01 ίϥϘϨʔγϣϯ, ʮ௿଎ RI ϏʔϜΛ༻͍ͨ 107 Pd ͷཅࢠɾॏཅࢠ༠‫ى‬൓Ԡଌఆʯ, ೔ຊ෺ཧֶձୈ 72 ճ೥࣍େձ, ‫۝‬भେֶ, ෱
Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
ೖ෦߂ଠ࿠ (‫ޱ‬಄ൃද), ಊԂণഢ, ࠓҪ৳໌, ಓਖ਼৽Ұ࿠, ԼӜ‫ڗ‬, େా৾ี, ୸‫ה‬૱೭, ઍլ৴޾, େ௡ल‫ڿ‬, ࣉ੢ߴ, ଞ ImPACT1702-01 ίϥϘϨʔγϣϯ, ʮ௿଎ RI ϏʔϜΛ༻͍ͨ 93 Zr ͷཅࢠɾॏཅࢠ༠‫ى‬൓Ԡଌఆʯ, ೔ຊ෺ཧֶձୈ 72 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
‫ݪ܀‬ಞࢤ (‫ޱ‬಄ൃද), தଜོ࢘, ۙ౻༸հ, ෢಺૱, ేถ‫و‬ਓ, ᴡ౻ರඒ, ҆ాণ߂, ࢁా‫وܒ‬, ౡా఩࿕, ࡾ໦੖ྤ, দຊਅ༝ࢠ,N. L. Achouri, T. Aumann, അ৔ल஧, F. Delaunay, P. Doornenbal, ෱ా௚थ, J. Gibelin, J. Hwang, Ҵลঘਓ, ү෦஧ত, ُాେี,S. KimD, খྛ৴೭, খྛढ़༤, ‫ٱ‬อහ޾, S. Leblond, J. Lee, M. Marques, ຊྛಁ, ଜҪେ஍, ଜ্఩໵, ෢౻‫ۏ‬ඒ, த௩ಙ‫ܧ‬, A. Navin,
N. A. Orr, େ௡ल‫ڿ‬, ࠤ౻޿ւ, ࠤ౻ًٛ, ਗ਼ਫཅฏ, ླ໦޺, ߴ‫ݡڮ‬ਓ, ஛ాߒ೭, ௪໺ହ޺, A. G. Tuﬀ, M. Vandebrouck, ถా݈Ұ࿠, ʮ22 C ͷΫʔϩϯ෼ղ൓Ԡʯ, ೔ຊ෺ཧֶձୈ 72 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
٢ཹ༐‫ى‬, ۙ౻༸հ (‫ޱ‬಄ൃද), தଜོ࢘, N. L. Achouri, T. Aumann, അ৔ल஧, F. Delaunay, P. Doornenbal, ෱ా௚थ, J. Gibelin,
J. Hwang, Ҵลঘਓ, ү෦஧ত, ُాେี, ؆໺େً, S. Kim, খྛ৴೭, খྛढ़༤, ‫ٱ‬อහ޾, S. Leblond, J. Lee, M. Marques, ೆํ྄‫ޗ‬, ຊྛಁ, ଜҪେ஍, ଜ্఩໵, ෢౻‫ۏ‬ඒ, தౢৎՅ, த௩ಙ‫ܧ‬, A. Navin, ੢੐࣐࿠, ੜӽॣ, N. A. Orr, େ௡ल‫ڿ‬, ࠤ౻޿ւ, ࠤ౻ًٛ, ਗ਼ਫཅฏ, ླ໦޺, ߴ‫ݡڮ‬ਓ, ஛ాߒ೭, ෢಺૱, ాதོ‫ݾ‬, ௪໺ହ޺, A. G. Tuﬀ, M. Vandebrouck, ถా݈Ұ࿠, ʮ25 O ͷෆม࣭ྔ֩෼ޫʯ, ೔ຊ෺ཧֶձୈ 72 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
ࡾ໦੖ྤ (‫ޱ‬಄ൃද), ۙ౻༸հ, தଜོ࢘, N. L. Achouri, T. Aumann, അ৔ल஧, F. Delaunay, P. Doornenbal, ෱ా௚थ, Julien Gibelin,
J. Hwang, Ҵลঘਓ, ү෦஧ত, ُాେี, ؆໺େً, S. Kim, খྛ৴೭, খྛढ़༤, ‫ٱ‬อහ޾, S. Leblond, J. Lee, M. Marques, ೆํ- 324 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

྄‫ޗ‬, ຊྛಁ, ଜҪେ஍, ଜ্఩໵, ෢౻‫ۏ‬ඒ, தౢৎՅ, த௩ಙ‫ܧ‬, A. Navin, ੢੐࣐࿠, ੜӽॣ, N. A. Orr, େ௡ल‫ڿ‬, ࠤ౻޿ւ, ࠤ౻ًٛ, ਗ਼ਫཅฏ, ླ໦޺, ߴ‫ݡڮ‬ਓ, ஛ాߒ೭, ෢಺૱, ాதོ‫ݾ‬, ௪໺ହ޺, A. G. Tuﬀ, M. Vandebrouck, ถా݈Ұ࿠, ʮՙిަ‫׵‬൓ԠΛ༻͍ͨඇଋറ֩ 28 F ͷ୳ࡧʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17 ೔–20 ೔.
٢ཹ༐‫ޱ( ى‬಄ൃද), ۙ౻༸հ, தଜོ࢘, N. L. Achouri, T. Aumann, അ৔ल஧, F. Delaunay, P. Doornenbal, ෱ా௚थ, J. Gibelin,
J. Hwang, Ҵลঘਓ, ү෦஧ত, ُాେี, ؆໺େً, S. Kim, খྛ৴೭, খྛढ़༤, ‫ٱ‬อහ޾, S. Leblond, J. Lee, M. Marques, ೆํ྄‫ޗ‬, ຊྛಁ, ଜҪେ஍, ଜ্఩໵, ෢౻‫ۏ‬ඒ, தౢৎՅ, த௩ಙ‫ܧ‬, A. Navin, ੢੐࣐࿠, ੜӽॣ, N. A. Orr, େ௡ल‫ڿ‬, ࠤ౻޿ւ, ࠤ౻ًٛ, ਗ਼ਫཅฏ, ླ໦޺, ߴ‫ݡڮ‬ਓ, ஛ాߒ೭, ෢಺૱, ాதོ‫ݾ‬, ௪໺ହ޺, A. G. Tuﬀ, M. Vandebrouck, ถా݈Ұ࿠, ʮ25 O ͷෆม࣭ྔ֩෼ޫʯ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17 ೔–20 ೔.
N. Fukuda (oral), “Current and near future BigRIPS DAQ,” RIBFDAQ workshop 2019, RIKEN, Wako, Japan, December 23, 2019.

Press releases
RIKEN ϓϨεൃද (2019.11.19) ϑοૉͱωΦϯͷಉҐ‫ݩ‬ૉͷଘࡏ‫ݶ‬քΛॳΊܾͯఆ—‫֩ࢠݪ‬ͷ஍ਤͷ‫ڥ‬քઢΛ 20 ೥ͿΓʹߋ৽—Ҵลঘਓ, ෱ా௚थ, ‫ٱ‬อහ޾, தଜོ࢘- 325 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Research Instruments GroupSAMURAI Team
1. Abstract

In collaboration with research groups in and outside RIKEN, the team designs, develops and constructs the SAMURAI spectrometer and relevant equipment that are and will be used for reaction experiments using RI beams at RI Beam Factory. The SAMURAI
spectrometer consists of a large superconducting dipole magnet and a variety of detectors to measure charged particles and neutrons.
After the commissioning experiment in March 2012, the team prepared and conducted, in collaboration with researchers in individual experimental groups, the first series of experiments with SAMURAI in May 2012. Then, several numbers of experiments were
well performed until now utilizing the property of SAMURAI. The team also provides a basis for research activities by, for example,
organizing collaboration workshops by researchers who are interested in studies or plan to perform experiments with the SAMURAI
spectrometer.

2. Major Research Subjects

Design, operation, maintenance and improvement of the SAMURAI spectrometer and its related research instruments. Supportand management for SAMURAI-based research programs. Generate future plans for next generation instruments for nuclear reaction
studies.

3. Summary of Research Activity

The current research subjects are summarized as follows:(1) Operation, maintenance and improvement of a large superconducting dipole magnet that is the main component of the SAMURAI spectrometer.
(2) Design, development and construction of various detectors that are used for nuclear reaction experiments using the SAMURAI
spectrometer.
(3) Preparation for planning experiments using SAMURAI spectrometer.
(4) Maintenance and improvement of the SAMURAI beam line.
(5) Formation of a collaboration platform called SAMURAI collaboration.
(6) Preparation for next generation spectrometer for nuclear reaction studies.

Members
Team Leader
Hideaki OTSU
Research & Development Scientist
Mizuki NISHIMURA
Junior Research Associate
Takato TOMAI

List of Publications & Presentations
Publications[Original papers]
A. Revel, O. Sorlin, F. M. Marqués, H. Otsu et al., “Extending the Southern Shore of the Island of Inversion to 28 F,” Phys. Rev. Lett. 124,
152502 (2020).
K. J. Cook, T. Nakamura, Y. Kondo, K. Hagino, H. Otsu et al., “Halo Structure of the Neutron-Dripline Nucleus 19 B,” Phys. Rev. Lett.
124, 212503 (2020).
M. L. Cortes, W. Rodriguez, P. Doornenbal, A. Obertelli, H. Otsu et al., “Shell evolution of N = 40 isotones towards 60 Ca: first spectroscopy of 62 Ti,” Phys. Lett. B 800, 135071 (2020).
Y. L. Sun, A. Obertelli, P. Doornenbal, H. Otsu et al., “Restoration of the natural E(1/2+1 )-E(3/2+1 ) energy splitting in odd-K isotopes
towards N = 40,” Phys. Lett. B 802, 135215 (2020).
S. Chen, J. Lee, P. Doornenbal, A. Obertelli, H. Otsu et al., “Quasifree Neutron Knockout from 54 Ca Corroborates Arising N = 34 Neutron
Magic Number,” Phys. Rev. Lett. 123, 142501 (2019).
A. Corsi, Y. Kubota, J. Casal, H. Otsu et al., “Structure of 13 Be probed via quasi-free scattering,” Phys. Lett. B 797, 134843 (2019).
Y. Kondo, T. Tomai, and T. Nakamura, “Recent progress and developments for experimental studies with the SAMURAI spectrometer,”Nucl. Instrum. Methods Phys. Res. B 463, 173–178 (2020).
L. Stuhl, M. Sasano, H. Otsu et al., “Study of spin-isospin responses of radioactive nuclei with the background-reduced neutron” spectrometer, PANDORA,” Nucl. Instrum. Methods Phys. Res. B 463, 189–194 (2020).
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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Y. Togano, T. Nakamura, Y. Kondo, H. Otsu et al., “New γ–ray detector CATANA for in-beam γ–ray spectroscopy with fast RI beams,”
Nucl. Instrum. Methods Phys. Res. B 463, 195–197 (2020).

[Proceedings]
M. Kurata-Nishimura et al., “Experimental study of nuclear equation of state using heavy ion collisions at RIKEN-RIBF,” Proc. 15th Int.
Symp. Origin of Matter and Evolution of Galaxies (OMEG15) JPS Conf. Proc. 31, (2020), p. 011023.
J. Gibelin et al., “Boron isotopes at the drip-line: 19 B,” Proc. of the 22nd Int. Conf. on Few-Body Problems in Physics Springer Proceedings in Physics 238 (2020), p. 103.
B. Monteagudo et al., “Structure of Beryllium isotopes beyond the neutron dripline,” Proc. of the 22nd Int. Conf. on Few-Body Problemsin Physics Springer Proceedings in Physics 238 (2020), p. 331.
Z. H. Yang et al., “Study of multi-neutron systems with the SAMURAI spectrometer,” Proc. of the 22nd Int. Conf. on Few-Body Problemsin Physics Springer Proceedings in Physics 238 (2020), p. 529.
A. I. Chilug, et al., “Study of the 9 C breakup through NP1412-SAMURAI29R1 experiment,” Carpathian Summer School of Physics 2018
(CSSP18), Sinaia, Romania, AIP Conference Proceedings 2076, 060001 (2019).

Presentations[International conferences/workshops]
M. Kurata–Nishimura, “Experimental study of nuclear equation of state using heavy ion collisions at RIKEN-RIBF,” The 15th International Symposium on Origin of Matter and Evolution of Galaxies, Kyoto, July 2–5, 2019.
M. Kurata–Nishimura, “Recent results of collective flow at neutron rich Sn+Sn collisions with 270 MeV/u,” 9th International Symposium
on Nuclear Symmetry Energy (NuSYM 2019), Da Nang, Vietnam, October 2–5, 2019.
T. Nakamura, “Recent progress of spectroscopic studies of nuclei near and beyond the neutron drip line,” Thirty Eighth International
Workshop on Nuclear Theory, Rila Mountains, Bulgaria, June 23–29, 2019.
Y. Kondo, “Spectroscopy of Oxygen isotopes beyond the neutron drip line,” Gordon Research Conference, “Exploring simple structural
patterns and the dynamics of nuclei,” New London, NH, US, June 16–21, 2019.
K. J. Cook, “Nuclear structure at the neutron drip-line: determining the halo nature of 19 B using coulomb breakup,” Gordon Research
Conference, “Exploring simple structural patterns and the dynamics of nuclei,” New London, NH, US, June 16–21, 2019.
Y. Kondo, “Spectroscopy of unbound nuclei towards the possible doubly magic nucleus 28 O,” 27th International Nuclear Physics Conference, Glasgow, UK, July 29–August 2, 2019.
T. Nakamura, “Spectroscopy of neutron-drip-line nuclei using SAMURAI at RIBF,” 27th International Nuclear Physics Conference,
Glasgow, UK, July 29–August 2, 2019.
T. Tomai, “Observation of excited states of 31 Ne using nuclear breakup reaction,” 27th International Nuclear Physics Conference, Glasgow,
UK, July 29–August 2, 2019.
T. Nakamura, “SAMURAI at RIBF: recent progress and near-future perspectives,” RIBF USERS Meeting 2019, RIKEN, Wako, Japan,
September 3–4, 2019.
T. Nakamura, “Multi-neutron clusters,” 4th International Workshop on Quasi-Free Scattering with Radioactive-Ion Beams, Maresias,
Brazil, October 9–13, 2019.
T. Nakamura, “Study of nuclear structure with radioactive beams,” WE-Heraeus Summer School on: Nuclear Physics in Astrophysics,
Heidelberg, Germany, September 9–16, 2019.
T. Nakamura, “Exploration of neutron drop line nuclei at RIBF,” 14th Asia-Pacific Physics Conference, Borneo Convention Centre
Kuching, Sarawak, Malaysia, November 17–22, 2019.
T. Nakamura, “Experiments on neutron-rich nuclei at SAMURAI at RIBF for astrophysics,” Workshop on “Origin of elements and cosmic
evolution: From big-bang to supernovae and mergers,” Beihang University, Beijing China, November 27–29, 2019.
T. Nakamura, “Exotic nuclei for investigating hierarchical structure of matter,” International Symposium on Clustering as a Window on
the Hierarchical Structure of Quantum Systems (CLUSHIQ2020), Beppu, Japan, January 23–24, 2020.
T. Nakamura, “Coulomb breakup of halo nuclei,” Japan-France Joint Workshop Clusters in Quantum Systems: From Atoms to Nuclei
and Hadrons, Fukuoka, Japan, January 27–31, 2020.
T. Nakamura, “Study of exotic nuclei along the neutron drip line and beyond,” Vth Topical Workshop on Modern Aspects of Nuclear
Structure, Bormio, Italy, February 4–9, 2020.
N. A. Orr, “High-energy direct reaction studies of light, nuclei beyond the neutron dripline,” 27th International Nuclear Physics Conference, Glasgow, UK, July 29–August 2, 2019,
N. A. Orr, “Direct reaction studies with high-energy radioactive beams of light nuclei beyond the neutron dripline,” Workshop on Challenges in Direct Nuclear Reactions, Beijing, China, August 19–21, 2019.
N. A. Orr, “Direct reaction studies of light neutron-rich nuclei beyond the dripline,” CENuM-RULiC Joint Workshop on Extreme Nuclear
States and Reactions, Daejeon, South Korea, October 31–November 2, 2019.
F. M. Marqués, “Probing nuclei with (too) many neutrons,” Gordon Research Conference, “Exploring simple structural patterns and the
dynamics of nuclei,” New London, NH, US, June 16–21, 2019.
F. M. Marqués, “The extremes of neutron richness,” Pisa Summer School—Rewriting Nuclear Physics Textbooks: One More Step Forward, Pisa, Italy, July 22–26, 2019.
F. M. Marqués, “Exotic structures in exotic nuclei,” 24th European Conference on Few-Body Problems in Physics, Guildford, UK, 2–6- 327 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

September 2019.
F. M. Marqués, “Two-neutron emission and related phenomena,” Workshop GDR RESANET—Nuclear Structure under Extreme Conditions, Caen, France, December 9–10, 2019.
J. Gibelin, “Neutron-rich boron isotopes at and beyond the drip line,” Japan-France Joint Workshop Clusters in Quantum Systems: From
Atoms to Nuclei and Hadrons, Fukuoka, Japan, January 27–31, 2020.
C. Lenain, “Search for Hydrogen 7 and its 4 neutron decay at SAMURAI,” Japan-France Joint Workshop Clusters in Quantum Systems:
From Atoms to Nuclei and Hadrons, Fukuoka, Japan, January 27–31, 2020.
M. Duer, “Study of the 8 He(p, pα)4n reaction,” International Workshop on Quasi-free Scattering with Radioactive Beams Maresias,
Brazil, QFS-RB19, October 13–18, 2019.
M. Knösel, “Precise measurement of the neutron-neutron scattering length,” International Workshop on Quasi-free Scattering with Radioactive Beams QFS-RB19, Maresias, Brazil, October 13–18, 2019.
C. Lehr, “Results from NeuLAND @ SAMURAI and the low-energy dipole response of 6, 8 He,” NUSTAR Annual Meeting, GSI Darmstadt, Germany, March 2–6, 2020,[SAMURAI International Collaboration Workshop 2019, Rikkyo University, Tokyo, Japan, August 30–31, 2019.]

Y. L. Sun et al., “STRASSE: a silicon tracker project for quasi free scattering at RIBF.”
T. Nakamura et al., “Development of high-granularity neutron detector array HIME.”
T. Aumann et al., “Status of TUDa funding application for construction of HIME and future experiments at SAMURAI.”
D. Rossi et al., “Invariant-mass spectroscopy at the low-Z shore of the island of inversion.”
H, Chae et al., “Study of unbound nuclei 33 Ne via one-proton knockout reactions.”
Sonja Storck, et al., “Analysis update on the lifetime measurement of the 26 O g.s. at SAMURAI.”
M. Duer, et al., “Analysis of the 8 He(p, pα)4n.”
Z. Yang, et al., “Quasi-free (p,pn) reaction with Borromean nuclei 11 Li,14 Be, and 17 B.”
V. Panin et al., “Status report of S24 experiment: investigation of unbound states in neutron-deficient 66 Se.”
H. Otsu et al., “HI-α invariant mass spectroscopy.”
S. Kim et al., “Study of unbound excited states in 17 C.”
Y. Hirai et al., “Study of Gamow-Teller transition in neutron-rich 11 Li’.
T. Pohl et al., “Analysis status of S31: probing isospin dependence of nucleon correlations using (p, pN) reaction.”
T. Motobayashi et al., “Nuclear breakup and coulomb dissociation of 9 C nucleus studied at RIBF RIKEN.”
T. Isobe et al., “Experimental study of density dependent symmetry energy at RIBF-SPiRIT.”
Z. H. Yang et al., “Status report of s034: study of 7 H and the tetraneutron using 8 He(p, 2p) reaction.”
P. Li et al., “Cluster structure of neutron-rich Beryllium isotopes investigated by cluster quasi-free scattering reaction.”Y. Togano et al., “Status report of dipole strength measurement performed in S09 and ImPACT.”
C. Lehr et al., “Analysis update on the low-energy dipole response of the halo nuclei 6, 8 He.”
J. Tanaka et al., “Search for preformed-alpha particles via alpha-knockout reaction from alpha-decay nuclei.”
N. A. Orr et al., “Status of NEBULA-Plus and possible future experiments.”
Y. KONDO et al., “Status report of the SAMURAI21 experiment.”
H. Wang et al., “Study on tensor correlation in neutron-rich nuclei via (p, pd) reaction.”[Domestic conferences/workshops]
தଜོ࢘, ʮΤΩκνοΫ֩ࢠଟମ‫Ͱܥ‬ඥղ͘෺࣭ͷ֊૚ߏ଄ʯ, ୈೋճΫϥελʔ֊૚ྖҬ‫ڀݚ‬ձ, ౦‫ۀ޻ژ‬େֶ, ౦‫ژ‬, 2019 ೥ 5
݄ 31–6 ݄ 1 ೔.
҆ా੟, ʮμΠχϡʔτϩϯ୳ࡧͷͨΊͷߴਫ਼ࡉதੑࢠ‫ݕ‬ग़‫ث‬ͷ։ൃ-IIʯ, 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
ࡾ໦੖ྤ, ʮՙిަ‫׵‬൓ԠΛ༻͍ͨඇଋറ֩ 28F ͷ୳ࡧʯ, 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
ౡా఩࿕, ʮதੑࢠա৒ඇଋറ֩ 30F ͷ֩෼ޫʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
٢ཹ༐‫ى‬, ʮ25 O ͷෆม࣭ྔ֩෼ޫʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձୈ 75 ճ೥࣍େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
தଜོ࢘, ʮଟதੑࢠΫϥελʔ୳ࡧͷͨΊͷ൓௓ཅࢠ‫ݕ‬ग़‫ ث‬CATANA/STRASSEʯ, ৽ֶज़ྖҬʮΫϥελʔ֊૚ʯʮྔࢠϏʔϜԠ༻ʯ߹ಉ‫ݕ‬ग़‫ث‬ϫʔΫγϣοϓ, ౦๺େֶ, ઋ୆, 2019 ೥ 9 ݄ 20–21 ೔.
҆ా੟, “Development of the neutron detector array with high granularity (HIME) for dineutron correlation measurement,” ৽ֶज़ྖҬ‫ڀݚ‬ʮྔࢠΫϥελʔͰಡΈղ͘෺࣭ͷ֊૚ߏ଄ʯεΫʔϧ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2020 ೥ 3 ݄ 2–4 ೔.
ւ࿝໊௚थ, ʮෆ҆ఆ֩ͷ४஄ੑࢄཚଌఆ༻ཅࢠ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ৽ֶज़ྖҬ‫ڀݚ‬ʮྔࢠΫϥελʔͰಡΈղ͘෺࣭ͷ֊૚ߏ଄ʯεΫʔϧ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2020 ೥ 3 ݄ 2–4 ೔.
ߴ‫߁ڮ‬ฏ, ʮߴ෼ղೳதੑࢠ‫ݕ‬ग़‫ ث‬HIME ͷ։ൃʯ, ৽ֶज़ྖҬ‫ڀݚ‬ʮྔࢠΫϥελʔͰಡΈղ͘෺࣭ͷ֊૚ߏ଄ʯεΫʔϧ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2020 ೥ 3 ݄ 2–4 ೔.
ేถ‫و‬ਓ, ʮม‫ܗ‬༠Ҿ‫ܕ‬ϋϩʔ֩ 31Ne ͷඇଋറྭ‫ى‬ঢ়ଶͷ୳ࡧʯ, ৽ֶज़ྖҬ‫ڀݚ‬ʮྔࢠΫϥελʔͰಡΈղ͘෺࣭ͷ֊૚ߏ଄ʯ
εΫʔϧ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2020 ೥ 3 ݄ 2–4 ೔.
ᴡ౻ರඒ, ʮதੑࢠա৒ϔϦ΢ϜಉҐମͷΫʔϩϯ෼ղ൓Ԡʯ, ৽ֶज़ྖҬ‫ڀݚ‬ʮྔࢠΫϥελʔͰಡΈղ͘෺࣭ͷ֊૚ߏ଄ʯεΫʔϧ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2020 ೥ 3 ݄ 2–4 ೔.
ᴡ౻ರඒ, ʮதੑࢠա৒ϔϦ΢ϜಉҐମͷΫʔϩϯ෼ղ൓Ԡʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 03 ݄

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

16–19 ೔.

[Poster presentation]
S. Storck, “Lifetime measurement of the 26 O g.s. at SAMURAI,” International Nuclear Physics Conference, Glasgow, UK, INPC2019,
July 29–August 2, 2019.

AwardsJ. Kahlbow, Giersch Award for Outstanding Doctoral Thesis 2019, 2019.

Press releases
O. Sorlin and F. M. Marqués, “L’oxygène-28 n’aurait pas la stabilité que la théorie lui prédit,” IN2P3-CNRS: Actualités - April 27, 2020,
https://in2p3.cnrs.fr/fr/cnrsinfo/loxygene-28-naurait-pas-la-stabilite-que-la-theorie-lui-predit .
Doornenbal Pieter, ᓎҪതّ, ʮ৽ຐ๏਺ 34 ͷ৽ͨͳূ‫—ڌ‬தੑࢠϊοΫΞ΢τ൓ԠͰ୳ΔΧϧγ΢Ϝ-54 ͷด֪ߏ଄—ʯ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 10 ݄ 18 ೔.

Doctor theses
B. Monteagudo, “Structure and neutron decay of the unbound Beryllium isotopes 15, 16 Be,” Université de Caen Normandie, November
2019.
J. Kahlbow, “The low-Z shore of the island of inversion: invariant-mass spectroscopy of the heavy fluorine isotopes 29 F∗ & 30 F at
SAMURAI with NeuLAND,” Technische Universität Darmstadt, 2019.

Master theses
M. Knösel, “Investigation of the dineutron system via quasi-free He-4-knockout reactions at He-6,” Technische Universität Darmstadt,
2019.
ࡾ໦੖ྤ, ʮՙిަ‫׵‬൓ԠΛ༻͍ͨඇଋറ֩ 28 F ͷ‫ڀݚ‬ʯ, ౦‫ۀ޻ژ‬େֶཧֶӃ෺ཧֶ‫ܥ‬.
ౡా఩࿕, ʮதੑࢠա৒ͳඇଋറϑοૉಉҐମͷ‫ڀݚ‬ʯ, ౦‫ۀ޻ژ‬େֶཧֶӃ෺ཧֶ‫ܥ‬.
‫ݪ܀‬ಞࢤ, ʮ22 C ͷΫʔϩϯ෼ղ൓Ԡʯ, ౦‫ۀ޻ژ‬େֶཧֶӃ෺ཧֶ‫ܥ‬.

Bachelor thesesߴ‫߁ڮ‬ฏ, ʮߴ෼ղೳதੑࢠ‫ݕ‬ग़‫ ث‬HIME ͷ։ൃʯ, ౦‫ۀ޻ژ‬େֶ.
ւ࿝໊௚थ, ʮෆ҆ఆ֩ͷ४஄ੑࢄཚଌఆ༻ཅࢠ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ౦‫ۀ޻ژ‬େֶ.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Research Instruments Group
Computing and Network Team
1. Abstract
This team is in charge of development, management and operation of the computing and network environment, mail and information servers and data acquisition system and management of the information security of the RIKEN Nishina Center.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Development, management and operation of the general computing servers
Development, management and operation of the mail and information servers
Development, management and operation of the data acquisition system
Development, management and operation of the network environment
Management of the information security

3. Summary of Research Activity
This team is in charge of development, management and operation of the computing and network environment, mail and information servers and data acquisition system and management of the information security. The details are described elsewhere in thisprogress report.
(1) Development, management and operation of the general computing servers
We are operating Linux/Unix NIS/NFS cluster system for the data analysis of the experiments and general computing. This
cluster system consists of eight computing servers with 64 CPU cores and totally 200 TB RAID of highly-reliable Fibre-channelinterconnection. Approximately 700 user accounts are registered on this cluster system. We are adopting the latest version of the
Scientific Linux (X86 64) as the primary operating system, which is widely used in the accelerator research facilities, nuclear physics
and high-energy physics communities in the world.
(2) Development, management and operation of the mail and information servers
We are operating RIBF.RIKEN.JP server as a mail/NFS/NIS server. This server is a core server of RIBF Linux cluster system.
Postfix has been used for mail transport software and dovecot has been used for imap and pop services. These software packages
enable secure and reliable mail delivery. Sophos Email Security and Control (PMX) installed on the mail front-end servers whichtags spam mails and isolates virus-infected mails. The probability to identify the spam is approximately 95–99%. We are operating
several information servers such as Web servers, Integrated Digital Conference (INDICO) server, Wiki servers, Groupware servers,
Wowza streaming servers. We have been operating approximately 70 units of wireless LAN access points in RNC. Almost the entire
radiation-controlled area of the East Area of RIKEN Wako campus is covered by wireless LAN for the convenience of experiments
and daily work.
(3) Development, management and operation of the data acquisition system
We have developed the standard data-acquisition system named as RIBFDAQ. This system can process up to 40 MB/s data. By
using crate-parallel readout from front-end systems such as CAMAC and VME, the dead time could be minimized. To synchronize theindependent DAQ systems, the time stamping system has been developed. The resolution and depth of the time stamp are 10 ns and48 bits, respectively. This time stamping system is very useful for beta decay experiments such as EURICA, BRIKEN and VANDLE
projects. One of the important tasks is the DAQ coupling, because detector systems with dedicated DAQ systems are transported to
RIBF from foreign facilities. In case of SAMURAI Silicon (NSCL/TUM/WUSTL), the readout system is integrated into RIBFDAQ.
The projects of MUST2 (GANIL), MINOS (CEA Saclay), NeuLAND (GSI) and TRB3 (TUM) cases, data from their DAQ systems
are transferred to RIBFDAQ and merged online. For SPIRIT (RIKEN/GANIL/CEA Saclay/NSCL), RIBFDAQ is controlled fromthe NARVAL-GET system that is a large-scale signal processing system for the time projection chamber. EURICA (GSI), BRIKEN(GSI/Univ. Liverpool/IFIC), VANDLE (UTK) and OTPC (U. Warsaw) projects, we adopt the time stamping system to apply individual
trigger for each detector system. In this case, data are merged in oﬄine. In addition, we are developing intelligent circuits based on
FPGA. General Trigger Operator (GTO) is an intelligent triggering NIM module. Functions of “common trigger management,” “gateand delay generator,” “scaler” are successfully implemented. The trigger system in BigRIPS DAQ is managed by 5 GTO modules. To
improve the data readout speed of VME system, we have successfully developed the MPV system which is a parallel readout extensionof the VME system. Data readout sequence is completely parallelized that helps to improve the DAQ deadtime. Thanks to the MPV
system, now the DAQ system in RIBF is 10 times faster than in 2007.
(4) Development, management and operation of the network environment
We have been managing the network environment collaborating with Information Systems Division in RIKEN. All the Ethernet
ports of the information wall sockets are capable of the Gigabit Ethernet connection (10/100/1000 BT). In addition, some 10 Gbps
networks port has been introduced to RIBF experimental area. Approximately 70 units of wireless LAN access points have been
installed to cover the almost entire area of Nishina Center.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53(5) Management of the information security
It is essential to take proper information security measures for information assets. We are managing the information security of
Nishina Center collaborating with Information Systems Division in RIKEN.

Members
Team Leader
Hidetada BABA
Research/Technical Scientist
Yasushi WATANABE (Senior Research Scientist)
Junior Research Associate
Fumiya GOTO
Special Temporary Research Scientist
Takashi ICHIHARA

List of Publications & Presentations
Presentations[International Conferences/Workshops]
H. Baba, “MOCO and MPV/cumputing infrastructure at RIBF, HOKUSAI and U-Tokyo/current and near future BigRIPS DAQ,” RIBFDAQ Workshop, Wako, Japan, December 23, 2019.

[Domestic Conferences/Workshops]
H. Baba, “RIBF DAQ,” SAMURAI International Collaboration Workshop, Toshima, Japan, August 30–31, 2019.
‫ޙ‬౻จ໵ (ΦϯϥΠϯൃදʣ, ʮMTV ࣮‫ݧ‬ͷใࠂ 2ʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
അ৔ल஧ (ΦϯϥΠϯൃදʣ, ʮฒྻԽ VME όεʹΑΔ DAQ ͷߴ଎Խʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020
೥ 3 ݄ 16–19 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Research Facility Development Division
Research Instruments Group
Detector Team
1. Abstract

This team is in charge of development, fabrication, and operation of various detectors used for nuclear physics experiments at
RIBF. Our current main mission is maintenance and improvement of detectors which are used at BigRIPS separator and its succeeding
beam lines for beam diagnosis and particle identification of RI beams. We are also engaged in R&D of new detectors that can be used
for higher-intensity RI beams. In addition, we are doing the R&D which uses the pelletron accelerator together with other groups.

2. Major Research Subjects

Development, fabrication, and operation of various detectors for nuclear physics experiments, including beam-line detectors which
are used for the production and delivery of RI beams (beam diagnosis and particle identification). R&D which uses the pelletron
accelerator.

3. Summary of Research Activity

The current research subjects are summarized as follows:(1) Maintenance and improvement of the beam-line detectors which are used at BigRIPS separator and its succeeding beam lines.
(2) Development of new beam-line detectors with radiation hardness and tolerance for higher counting rates.
(3) Management of the pelletron accelerator and R&D which uses the pelletron.

Members
Team Leader
Hiromi SATO
Research/Technical Scientist
Tokihiro IKEDA (Senior Research Scientist)
Special Temporary Employee
Manabu HAMAGAKIVisiting Scientist
Takeshi KOIKE (Tohoku University)
Student Trainees
Shunya KAWAMURA (Toho University)
Masaya SAKAI (University of Tokyo)
Kento TAKEMOTO (University of Tokyo)

Yuka HIKIMA (Toho University)
Mitsumasa MORI (Toho University)

List of Publications & Presentations
Publications[Original papers]
D. S. Ahn, N. Fukuda, H. Geissel, N. Inabe, N. Iwasa, T. Kubo, K. Kusaka, D. J. Morrissey, D. Murai, T. Nakamura, M. Ohtake, H. Otsu,
H. Sato, B. M. Sherrill, Y. Shimizu, H. Suzuki, H. Takeda, O. B. Tarasov, H. Ueno, Y. Yanagisawa, and K. Yoshida, “Location of theneutron dripline at fluorine and neon,” Phys. Rev. Lett. 123, 212501 (2019).
H. Wang, H. Otsu, N. Chiga, S. Kawase, S. Takeuchi, T. Sumikama, S. Koyama, H. Sakurai, Y. Watanabe, S. Nakayama, D. S. Ahn,
H. Baba, S. D. Chen, K. Chikaato, M. L. Cortes, N. Fukuda, A. Hirayama, R. Hosoda, T. Isobe, S. Kawakami, Y. Kondo, S. Kubono,
Y. Maeda, S. Masuoka, S. Michimasa, I. Murray, R. Nakajima, T. Nakamura, K. Nakano, M. Nishimura, T. Ozaki, A. Saito, T. Saito,
H. Sato, Y. Shimizu, S. Shimoura, P. -A. Söderström, Y. Soudo, X. H. Sun, J. Suwa, D. Suzuki, H. Suzuki, H. Takeda, M. Takechi,
Y. Togano, T. Tomai, H. Yamada, M. Yasuda, and K. Yoshida, “Enhancement of element production by incomplete fusion reaction withweakly bound deuteron,” Commun. Phys. 2, 78 (2019).
A. Corsi, Y. Kubota, J. Casal, M. Gomez-Ramos, A. M. Moro, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono,
J. Feng, F. Flavigny, J. -M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim,
Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F. M. Marques,
T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, N. A. Orr, S. Ota, H. Otsu, T. Ozaki,
V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. -Y. Rousse, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano,
H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y. L. Sun, M. Tabata, Y. Togano, J. Tsubota, T. Uesaka, Z. H. Yang,
J. Yasuda, K. Yoneda, and J. Zenihiro, “Structure of 13 Be probed via quasi-free scattering,” Phys. Lett. B 797, 134843 (2019).

[Proceedings]- 332 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

M. Ohno, T. Irimatsugawa, Y. Miura, H. Takahashi, T. Ikeda, C. Otani, M. Sakama, and N. Matsufuji, “Calorimetry of heavy charged
particle by superconducting transition-edge sensor,” Journal of Low Temperature Physics 193, 1222–1227 (2018).
R. Smith, M. Ohno, Y. Miura, N. Nakada, Y. Mitsuya, H. Takahashi, T. Ikeda, C. Otani, M. Sakama, N. Matsufuji, T. Irimatsugawa,
S. Kohjiro, H. Yamamori, and F. Hirayama, “Microcalorimetry of carbon ion beam for medical treatment by transition edge sensor,”
Journal of Low Temperature Physics 199, 1012–1017 (2020).
T. Ikeda, M. Ikekame, Y. Hikima, M. Mori, S. Kawamura, T. Minowa, and W. -G. Jin, “Profile measurements of MeV ion microbeams
in atmosphere extracted from single tapered glass capillaries with an end window,” Nucl. Instrum. Methods Phys. Res. B 470, 42–47(2020).
T. Sumikama, T. Kubo, N. Fukuda, D. S. Ahn, H. Takeda, Y. Shimizu, H. Suzuki, N. Inabe, D. Murai, H. Sato, K. Kusaka, Y. Yanagisawa,
M. Ohtake, and K. Yoshida, “First success of RI-beam separation and particle identification for nuclei with atomic number Z > 82 at
RIKEN RI beam factory,” Nucl. Instrum. Methods Phys. Res. B 463, 237–240 (2020).

Presentations[International conferences/workshops]
T. Ikeda, M. Ikekame, Y. Hikima, M. Mori, T. Kawamura, T. Minowa, and W. -G. Jin (oral), “Profile measurements of MeV ion microbeams in atmosphere extracted from single tapered glass capillary with an end window,” 13th European Conference on Accelerators
in Applied Research and Technology (ECAART13), Split, Croatia, May 5–10, 2019.
M. Mori, T. Kawamura, T. Ikeda, T. Minowa, and W. -G. Jin (poster), “Profile measurement of laser microbeam produced by glass
capillaries : tilting dependence,” 24th Optoelectronics and Communications Conference/International Conference on Photonics in
Switching and Computing 2019 (OECC/PSC 2019), Fukuoka, Japan, July 7–11, 2019.
R. Smith, M. Ohno, Y. Miura, N. Nakata, H. Takahashi, Y. Mitsuya, N. Matsufuji, M. Sakama, T. Ikeda, T. Irimatsugawa, S. Koujiro,
H. Yamamori, F. Hirayama, and C. Otani (poster), “Microcalorimetry of carbon ion beam for medical treatment by transition edge
sensor,” 18th International Workshop on Low Temperature Detectors (LTD-18), Milano, Italy, July 22–26, 2019.
T. Ikeda, M. Ikekame, Y. Hikima, M. Mori, T. Kawamura, T. Minowa, and W. -G. Jin (poster), “Measurement of proton microbeam
profiles in atmosphere produced by single tapered glass capillary optics with an end window,” International Conference on Photonic,
Electronic and Atomic Collisions (ICPEAC2019), Deauville, France, July 23–30, 2019.
T. Kawamura, T. Ikeda, M. Mori, and W. -G. Jin (poster), “Development of UV-laser microbeam cell irradiation system by glass capillary
optics : estimation of density enhancement,” 16th International Congress of Radiation Research (ICRR2019), Manchester, UK, August
25–29, 2019.
Y. Hikima, T. Ikeda, M. Ikekame, M. Mori, T. Kawamura, and W. -G. Jin (poster), “Fine structure evaluation by pattern recognition for ion
microbeam extracted from tapered glass capillary optics,” 23rd International Workshop on Inelastic Ion-Surface Collisions (IISC-23),
Matsue, Japan, November 17–22, 2019.

[Domestic conferences/workshops]
஑ా࣌ߒ, ඿ֶ֞, ࠤ౻޿ւ (‫ޱ‬಄ൃද), ʮཧԽֶ‫͚͓ʹॴڀݚ‬ΔλϯσϜՃ଎‫ث‬ͷ‫ݱ‬ঢ়ʢ2018–2019 ೥౓ʣʯ, ୈ 32 ճλϯσϜՃ଎‫ͦͼٴث‬ͷपลٕज़ͷ‫ڀݚ‬ձ, ਆ‫ށ‬େֶ, ਆ‫ށ‬, 2019 ೥ 7 ݄ 5–6 ೔.
ञҪխ࠸, ஑ా࣌ߒ, ࣲా३࢙, ஛ຊ݈ਓ, ্ࡔॆ (ϙελʔ), ʮα ઢ࣏ྍͷͨΊͷ He ΠΦϯϏʔϜ DNA রࣹ෼ੳͷ‫ڀݚૅج‬ʯ, ୈ
16 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ‫౎ژ‬େֶ, ‫౎ژ‬, 2019 ೥ 7 ݄ 31 ೔–8 ݄ 3 ೔.
஑ా࣌ߒ (‫ޱ‬಄ൃද), ʮϑλ෇ΨϥεΩϟϐϥϦʔʹΑΔ MeV ΠΦϯϚΠΫϩϏʔϜরࣹͰੜͨ͡ࡉ๔֩಺ΠΦϯτϥοΫͷղੳʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ‫ذ‬ෞେֶ, ‫ذ‬ෞ, 2019 ೥ 9 ݄ 10–13 ೔.
ञҪխ࠸, ஑ా࣌ߒ, ࣲా३࢙, ஛ຊ݈ਓ, ্ࡔॆ (‫ޱ‬಄ൃද), ʮα ઢ࣏ྍͷͨΊͷ He ΠΦϯϚΠΫϩϏʔϜ DNA রࣹ෼ੳͷ‫ૅج‬‫ڀݚ‬ʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥ळͷେձ, ෋ࢁେֶ, ෋ࢁ, 2019 ೥ 9 ݄ 11–13 ೔.
ࡾ໦੖ྤ, ۙ౻༸հ, தଜོ࢘, Nadia Lynda Achouri, Thomas Aumann, അ৔ल஧, Franck Delaunay, Pieter Doornenbal, ෱ా௚थ, Julien
Gibelin, Jongwon Hwang, Ҵลঘਓ, ү෦஧ত, ُాେี, ؆໺େً, Sunji Kim, খྛ৴೭, খྛढ़༤, ‫ٱ‬อහ޾, Sylvain Leblond,
Jenny Lee, Miguel Marques, ೆํ྄‫ޗ‬, ຊྛಁ, ଜҪେ஍, ଜ্఩໵, ෢౻‫ۏ‬ඒ, தౢৎՅ, த௩ಙ‫ܧ‬, Alahari Navin, ੢੐࣐࿠, ੜӽॣ, Nigel Andrew Orr, େ௡ल‫ڿ‬, ࠤ౻޿ւ, ࠤ౻ًٛ, ਗ਼ਫཅฏ, ླ໦޺, ߴ‫ݡڮ‬ਓ, ஛ాߒ೭, ෢಺૱, ాதོ‫ݾ‬, ௪໺ହ޺, Adam
Garry Tuﬀ, Marine Vandebrouck, ถా݈Ұ࿠ (‫ޱ‬಄ൃද), ʮՙిަ‫׵‬൓ԠΛ༻͍ͨඇଋറ֩ 28 F ͷ୳ࡧʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
٢ཹ༐‫ى‬, ۙ౻༸հ, தଜོ࢘, Nadia Lynda Achouri, Thomas Aumann, അ৔ल஧, Franck Delaunay, Pieter Doornenbal, ෱ా௚थ, Julien
Gibelin, Jongwon Hwang, Ҵลঘਓ, ү෦஧ত, ُాେี, ؆໺େً, Sunji Kim, খྛ৴೭, খྛढ़༤, ‫ٱ‬อහ޾, Sylvain Leblond,
Jenny Lee, Miguel Marques, ೆํ྄‫ޗ‬, ຊྛಁ, ଜҪେ஍, ଜ্఩໵, ෢౻‫ۏ‬ඒ, தౢৎՅ, த௩ಙ‫ܧ‬, Alahari Navin, ੢੐࣐࿠, ੜӽॣ, Nigel Andrew Orr, େ௡ल‫ڿ‬, ࠤ౻޿ւ, ࠤ౻ًٛ, ਗ਼ਫཅฏ, ླ໦޺, ߴ‫ݡڮ‬ਓ, ஛ాߒ೭, ෢಺૱, ాதོ‫ݾ‬, ௪໺ହ޺, Adam
Garry Tuﬀ, Marine Vandebrouck, ถా݈Ұ࿠ (‫ޱ‬಄ൃද), ʮ25 O ͷෆม࣭ྔ֩෼ޫʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
஑ా࣌ߒ, ࠤ౻޿ւ (‫ޱ‬಄ൃද), ʮλϯσϜՃ଎‫ʹث‬ΑΔΩϟϐϥϦʔϚΠΫϩϏʔϜͷੜ੒ͱԠ༻ʯ, ୈ 80 ճԠ༻෺ཧֶձळ‫ق‬ֶज़ߨԋձ, ๺ւಓେֶ, ࡳຈ, 2019 ೥ 9 ݄ 18–21 ೔.
εϛεϥΠΞϯ, େ໺խ࢙, ߴ‫ߒڮ‬೭, ࡾ௡୩༗‫و‬, ࡾӜོٛ, தా௚थ, দ౻੒߂, ࡔؒ੣, ஑ా࣌ߒ (‫ޱ‬಄ൃද), ʮ௒఻ಋసҠ୺ηϯαʹΑΔ࣏ྍ༻୸ૉॏཻࢠΧϩϦϝτϦʯ, ୈ 80 ճԠ༻෺ཧֶձळ‫ֶق‬ज़ߨԋձ, ๺ւಓେֶ, ࡳຈ, 2019 ೥ 9 ݄ 18–21 ೔.
େ໺խ࢙, εϛεϥΠΞϯ, ࡾӜོٛ, தా௚थ, ࡾ௡୩༗‫و‬, ߴ‫ߒڮ‬೭, ஑ా࣌ߒ, ࡔؒ੣, দ౻੒߂ (‫ޱ‬಄ൃද), ʮ௒఻ಋసҠ୺ηϯαʹΑΔॏཻࢠϏʔϜਫ਼ີ‫ܭ‬ଌʯ, ୈ 80 ճԠ༻෺ཧֶձळ‫ֶق‬ज़ߨԋձ, ๺ւಓେֶ, ࡳຈ, 2019 ೥ 9 ݄ 18–21 ೔.
஑ా࣌ߒ, Ҿؒ༒Ֆ, ৿ޫਖ਼, Տଜढ़࠸, ۚӴࠃ (‫ޱ‬಄ൃද), ʮϑλ෇ΨϥεΩϟϐϥϦʔͰੜ੒͞Εͨ MeV ΠΦϯϚΠΫϩϏʔϜͷ
CR-39 ʹΑΔεϙοτߏ଄ධՁʯ, ୈ 62 ճ์ࣹઢԽֶ౼࿦ձ, ෱Ҫେֶෟଐࠃࡍ‫ॴڀݚֶ޻ྗࢠݪ‬, ರլ, 2019 ೥ 9 ݄ 23–25 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

ञҪխ࠸, ஑ా࣌ߒ, ࣲా३࢙, ઘխࢠ, ஛ຊ݈ਓ, ্ࡔॆ (‫ޱ‬಄ൃද), ʮα ઢ࣏ྍͷͨΊͷ He ΠΦϯϚΠΫϩϏʔϜ DNA রࣹ෼ੳͷ‫ڀݚૅج‬ʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2020 ೥य़ͷ೥ձ, ෱ౡେֶ, ෱ౡ, 2020 ೥ 3 ݄ 16–18 ೔.
ຊྛಁ, ஑ా࣌ߒ, ੴࢁത߃, ϐʔλʔ υʔωϯόϧ, ࠤ౻޿ւ, ্໺लथ (‫ޱ‬಄ൃද), ʮਔՊεΫʔϧ—‫֩ࢠݪ‬൓Ԡ࣮‫ݧ‬Λத৺ͱֶͨ͠෦ֶੜ޲͚ࠃࡍϓϩάϥϜʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձʢ2020 ೥ʣ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
஑ా࣌ߒ, ञҪխ࠸, ஛ຊ݈ਓ, ࣲా३࢙, ઘխࢠ, ্ࡔॆ (‫ޱ‬಄ൃද), ʮΨϥεΩϟϐϥϦʔͰੜ੒͞ΕͨΠΦϯϚΠΫϩϏʔϜʹΑΔ RPE ࡉ๔ͷ DNA ଛই༠ൃ࣮‫ݧ‬ʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձʢ2020 ೥ʣ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
Ҿؒ༒Ֆ, ஑ా࣌ߒ, ඿ֶ֞, ۚӴࠃ (‫ޱ‬಄ൃද), ʮΨϥεΩϟϐϥϦʔޫֶ‫ʹܥ‬ΑΔΠΦϯϚΠΫϩϏʔϜͷরࣹ‫ͱ཭ڑ‬εϙοταΠζͷ૬ؔʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձʢ2020 ೥ʣ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.

AwardsՏଜढ़࠸, JSRC Young Scientist Award for 16th International Congress of Radiation Research (ICRR2019), ೔ຊ์ࣹઢԽֶձ, 2019 ೥
7 ݄ 12 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Accelerator Applications Research Division
Beam Mutagenesis Group
1. Abstract
This group promotes biological applications of ion beams from RI Beam Factory (RIBF). Ion Beam Breeding Team studies
various biological eﬀects of fast heavy ions and develops new technology to breed plants and microbes by heavy-ion irradiations.
Plant Genome Evolution Research Team studies the eﬀect of chromosomal rearrangements on plant genomes and phenotypes.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Biological eﬀects of fast heavy ions
Molecular nature of DNA alterations induced by heavy-ion irradiation
Research and development of heavy-ion breeding
Identification of plant sex-determining genes using mutants and their evolutionary study

3. Summary of Research Activity
Summary of research activities of the two teams are given in the sections of each team.

MemberDirector
Tomoko ABE

List of Publications & Presentations
Publications and presentations for each research team are listed in subsections.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Accelerator Applications Research Division
Beam Mutagenesis GroupIon Beam Breeding Team
1. Abstract

Ion beam breeding team studies various biological eﬀects of fast heavy ions. It also develops new technique to breed plants andmicrobes by heavy-ion irradiations. Fast heavy ions can produce dense and localized ionizations in matters along their tracks, incontrast to photons (X rays and gamma rays) which produce randomly distributed isolated ionizations. These localized and dense
ionization can cause double-strand breaks of DNA which are not easily repaired and result in mutation more eﬀectively than singlestrand breaks. A unique feature of our experimental facility at the RIKEN Ring Cyclotron (RRC) is that we can irradiate living
tissues in atmosphere since the delivered heavy-ion beams have energies high enough to penetrate deep in matter. This team utilizes adedicated beam line (E5B) of the RRC to irradiate microbes, plants and animals with beams ranging from carbon to iron. Its researchsubjects cover study of ion-beam radiation mutagenesis, genome-wide analyses of mutation, and development of new plants andmicrobial varieties by heavy-ion irradiation. Thirty new varieties have already been brought to the market.

2. Major Research Subjects(1) Study on the biological eﬀects by heavy-ion irradiation(2) Study on the molecular nature of DNA alterations induced by heavy-ion irradiation(3) Innovative applications of heavy-ion beams

3. Summary of Research Activity

We study biological eﬀects of fast heavy ions from the RRC using 135 A MeV C, N, Ne ions, 95 A MeV Ar ions, 90 A MeV Fe
ions and from the IRC using 160 A MeV Ar ions. We also develop breeding technology of microbes and plants. Main subjects are:(1) Study on the biological eﬀects by heavy-ion irradiation
Heavy-ion beam deposits a concentrated amount of dose at just before stop with severely changing the linear energy transfer(LET). The peak of LET is achieved at the stopping point and known at the Bragg peak (BP). Adjusting the BP to target malignant
cells is well known to be eﬀective for cancer therapy. On the other hand, a uniform dose distribution is a key to the systematic study
for heavy-ion mutagenesis, thus to the improvement of the mutation eﬃciency. Plants and microbes therefore, are irradiated usingions with stable LET. We investigated the eﬀect of LET ranging from 23 to 640 keV/µm, on mutation induction using dry seeds ofthe model plants Arabidopsis thaliana and rice (Oryza sativa L.). The most eﬀective LET (LETmax) was 30 keV/µm in Arabidopsis
and rice dry seeds. LETmax irradiations showed the same mutation rate as that by chemical mutagens, which typically cause highmutation rate. The LETmax of imbibed rice seeds and dry wheat (Triticum monococcum) seeds were shown to be 50–63 keV/µm and50 keV/µm, respectively. In the case of microbe, filamentous fungus (Neurospora crassa), the Ar ions at 290 keV/µm demonstrated
higher mutagenic activity than the Fe-ions at 640 keV/µm. Thus, the LET is an important factor to be considered in heavy-ion
mutagenesis.
(2) Study on the molecular nature of DNA alterations induced by heavy-ion irradiation
We analyzed the DNA alterations corresponding to morphological mutants in Arabidopsis and rice. In the mutants from C- andAr-ions irradiations, the majority of the induced mutations were deletions. The proportion of large deletions (>100 bp) increased
with increasing LET. We concluded that the size of deletions generated by heavy-ion beam irradiation increased with increasing LET.
Whole-genome analysis by high-through put sequencing is a powerful tool used to characterize the nature of induced mutations.
We also developed a new pipeline named the Automated Mutation Analysis Pipeline (AMAP), for the rapid detection of wholegenome mutations in Arabidopsis. We comprehensively characterized the mutation eﬀects of ion beams of C (30 keV/µm) and Ar(290 keV/µm) by whole-genome mutational analysis on eight morphological mutants with AMAP. C ions at a dose of 400 Gy mainly
induced single-nucleotide variants (SNVs) and small insertions and deletions (InDels) at a rate of 57 sites per mutant genome. LETmax
irradiation is eﬀective for breeding because of its very high mutation frequency. Most mutations are SNV and small deletions which
are capable of disrupting a single gene. Thus, irradiation can eﬃciently generate knockout mutants of a target gene and can be applied
to reverse genetics. On the other hand, irradiation with Ar ions at a dose of 50 Gy showed a mutation spectrum diﬀerent from that at
LETmax. The proportion of SNVs and small InDels was low at a rate of 28 sites per mutant genome, while that of large deletions andchromosomal rearrangements was high (10 sites per mutant genome). As such, higher LET irradiation is promising as a new mutagen
suitable for the functional analysis of tandem duplicated genes.
(3) Innovative application of heavy-ion beams
In 1999, we formed a consortium for ion-beam breeding consisting of 24 groups. In 2019, the consortium grew to 184 groups
from Japan and 20 from overseas. Previously, the ion-beam breeding procedures were carried out using mainly flowers and ornamental
plants. We have recently put a new non-pungent and tearless onion, ‘Smile ball,’ on the market along with ‘Kiku Meigetsu,’ an edible
late flowering chrysanthemum. In addition, a new project was launched to expand the cultivation area of this variety of chrysanthemum
in Yamagata prefecture. Beneficial variants have been cultivated for various plant species, such as high yield sea weeds, lipidshyperaccumulating unicellular alga, large marine plankton and lettuce with a low browning property as a cut vegetable. We collaborate- 336 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

with Miyagi prefectural government and Tohoku University to breed salt-resistant lines in the more delicious commercial rice varieties,‘Hitomebore’ and ‘Manamusume.’ Imbibed seeds were irradiated with the LETmax (C-ions) on 16 April, 2011. We have isolated
a candidate line of salt-resistant mutant from 719 M2 progenies grown in the saline paddy field in 2012. This line grew well after
transplantation and had high yield in common paddy field as well. By broadening the target of heavy-ion breeding extending fromflowers to crops such as grains, the technology will contribute to solving the global problems of food shortage and environmental
destruction.

Members
Team Leader
Tomoko ABE
Research/Technical Scientists
Tokihiro IKEDA (Senior Research Scientist)
Masako IZUMI (Senior Research Scientist)
Teruyo TSUKADA (Senior Research Scientist)

Kazuhide TSUNEIZUMI (Senior Research Scientist)
Ryouhei MORITA (Technical Scientist)

Research & Development Scientist
Hiroyuki ICHIDA
Technical Staﬀ I
Yoriko HAYASHI

Yuki SHIRAKAWA

Technical Staﬀ II
Sumie OHBU

Mieko YAMADASpecial Temporary Technical Scientists
Hiroshi ABE

Katsunori ICHINOSE

Research Consultant
Masahiro MII (Chiba Univ.)
Visiting Scientists
Ayumi DEGUCHI (Chiba Univ.)
Makoto FUJIWARA (Sophia Univ.)
Eitaro FUKATSU (Forestry and Forest Products Res. Inst.)
Tomonari HIRANO (Univ. of Miyazaki)
Akiko HOKURA (Tokyo Denki Univ.)
Yutaka MIYAZAWA (Yamagata Univ.)
Kazumitsu MIYOSHI (Chiba Univ.)
Toshikazu MORISHITA (Nat’l Agriculture and Food Res.
Org.)
Koji MURAI (Fukui Prefectural Univ.)

Kyosuke NIWA (Tokyo Univ. of Marine Sci. and Tech.)
Norihiro OHTSUBO (Kyoto Prefectural Univ.)
Tadashi SATO (Tohoku Univ.)
Yoichi SATO (Riken Food Co., Ltd.)
Kenichi SUZUKI (Suntory Flowers Co., Ltd.)
Hinako TAKEHISA (Nat’l Inst. of Agrobiological Sci.)
Masanori TOMITA (Central Res. Inst. of Electric Power Industry)
Masao WATANABE (Tohoku Univ.)
Takeshi YAMAKI (Riken Vitamin Co., Ltd.)

Visiting Technicians
Yukiko KANAZAWA (Nippon Beet Sugar Manufacturing Co.,Ltd.)
Miho MOGAMIYA (Riken Food Co., Ltd.)
Research Fellow
Hironari UCHIDA (Saitama Agricultural Tech. Res. Center)
Student Trainee
Yuta HARUNARI (Tokyo Denki Univ.)
Part-time Worker
Haruka WATANABE (Administrative Part-time Worker II)- 337 -

Daisuke SAITO (Riken Food Co., Ltd.)
Takuji YOSHIDA (Takii & Co., Ltd)

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

List of Publications & Presentations
Publications[Original papers]
T. Kashiwabara, K. Tanoi, N. Kitajima, A. Hokura, T. Abe, T. Nakanishi, and I. Nakai, “Comparative in vivo imaging of arsenic andphosphorus in Pteris vittata gametophyte by synchrotron µ-XRF and radioactive tracer techniques,” Chem. Lett. 48, 319–321 (2019).
Y. Hayashi, S. Ishii, T. Hirano, K. Ichinose, Y. Kazama, and T. Abe, “New ornamental cherry cultivars induced by heavy-ion beamirradiation,” Acta Hortic. 1235, 99–103 (2019).
Ѩ෦஌ࢠ, ࢢా༟೭, ৿ాཽฏ, େ໺๛, ௕୩७޺, ߴ৓‫ܒ‬Ұ, ാԼণൣ, ଜҪߞೋ, ʮϛϡʔλήϊϛΫεͱมҟ౷߹σʔλϕʔεͷߏஙʯ, JATAFF δϟʔφϧ 7, 19–23 (2019).
M. Krasovec, Y. Kazama, K. Ishii, T. Abe, and D. A. Filatov, “Immediate dosage compensation is triggered by the deletion of Y-linked
genes in Silene latifolia,” Current Biol. 29, 2214–2221 (2019).
H. Kawamoto, K. Yamanaka, A. Koizumi, K. Ishii, Y. Kazama, T. Abe, and S. Kawano, “An asexual flower of Silene latifolia andMicrobotryum lychnidis-dioicae promotes sex-organ development,” PLoS One 14, e0217329 (2019).
H. Ichida and T. Abe, “An improved and robust method to eﬃciently deplete repetitive elements from complex plant genomes,” Plant Sci.
280, 455–60 (2019).
H. Murata, S. Nakano, T. Yamanaka, T. Shimokawa, T. Abe, H. Ichida, Y. Hayashi, K. Tahara, and A. Ohta, “Conversion from mutualism to parasitism: a mutant of the ectomycorrhizal agaricomycete Tricholoma matsutake that induces stunting, wilting, and root
degeneration in seedlings of its symbiotic partner, Pinus densiflora, in vitro,” Botany 97, 463–474 (2019).
H. Ichida, R. Morita, Y. Shirakawa, Y. Hayashi, and T. Abe, “Targeted exome sequencing of unselected heavy-ion beam-irradiatedpopulations reveals less-biased mutation characteristics in the rice genome,” Plant J 98, 301–314 (2019).
R. Morita, H. Ichida, K. Ishii, Y. Hayashi, H. Abe, Y. Shirakawa, K. Ichinose, K. Tsuneizumi, T. Kazama, K. Toriyama, T. Sato, and
T. Abe, “LONG GRAIN 1: a novel gene that regulates grain length in rice,” Mol. Breed. 39, 135–142 (2019).
Y. Sawada, M. Sato, M. Okamoto, J. Masuda, S. Yamaki, M. Tamari, Y. Tanokashira, S. Kishimoto, A. Ohmiya, T. Abe, and M. Y. Hirai, “Metabolome-based discrimination of chrysanthemum cultivars for the eﬃcient generation of flower color variations in mutation
breeding,” Metabolomics 15, 118–129 (2019).

Presentations[International conferences/workshops]
H. Ichida (invited), R. Morita, Y. Shirakawa, Y. Hayashi, and T. Abe, “A less-biased approach to characterize carbon-ion beam-induced
mutations by whole exome sequencing of unselected M2 populations in rice,” Rice Functional Genomics Workshop in XXVII Plant &Animal Genome Conference, San Diego, USA, January 12–16, 2019.
K. Niwa (poster), T. Abe, and A. Kobiyama, “Possibility of polyploidy breeding using cryptic species in the marine crop Pyropia yezoensis(Bangiales, Rhodophyta),” 23rd International Seaweed Symposium, Jeju, Korea, April 28–May 3, 2019.
T. Abe (invited), H. Ichida, Y. Hayashi, Y. Shirakawa, K. Ishii, and R. Morita, “Ion-beam radiation mutagenesis and plant mutation
breeding,” 14th Conference of Society for the Advancement of the Breeding Research in Asia and Oceania, Gwangju, Korea, July 2–5,
2019.
H. Murata (oral), S. Nakano, T. Yamanaka, T. Shimokawa, T. Abe, H. Ichida, Y. Hayashi, K. Tahara, and A. Ohta, “Radiation mutagenesisof the ectomycorrhizal fungus Tricholoma matsutake,” The 10th International Workshop on Edible Mycorrhizal Mushrooms, Nagano,
Japan, October 23, 2019.
T. Hioki (oral), H. Kunitake, T. Abe, and T. Hirano, “Analysis of petal size regulatory mechanisms in flower mutant of Arabidopsis
thaliana,” The 14th JKTC Seminar, Qingdao, China, October 18–21, 2019.

[Domestic conferences/workshops]Ѩ෦஌ࢠ (ট଴ߨԋ), ྛґࢠ, ࢢా༟೭, ʮIon Beam Mutagenesis ͱΠΦϯϏʔϜ඼छվྑϓϥοτϑΥʔϜʯ, ୈ 1 ճ ॏɾΫϥελʔΠΦϯϏʔϜར༻ʹΑΔඍੜ෺༝དྷߴੜ࢈ੑΤωϧΪʔ ‫ڥ؀‬γϯϙδ΢Ϝ, ஜ೾େֶ, ͭ͘͹, 2019 ೥ 1 ݄ 29 ೔.
্ా७ฏ (‫ޱ‬಄ൃද), ෩ؒ༟հ, Ѩ෦஌ࢠ, ଜҪߞೋ, ʮҰཻ‫ܥ‬ίϜΪ DV92 ‫ܥ‬౷ʹ͓͚ΔՖ੒஗Ԇมҟମ late-heading 2ʙ5 (lh2ʙ5) ͷಉఆʯ, ೔ຊҭछֶձ ୈ 135 ճߨԋձ, ઍ༿େֶ, ઍ༿, 2019 ೥ 3 ݄ 16–17 ೔.
, ೔ຊҭछֶձ ୈ 135 ճߨԋࢢా༟೭ (‫ޱ‬಄ൃද), Ѩ෦஌ࢠ, ʮޮ཰తͳ൓෮഑ྻআ‫ٕڈ‬ज़ͷ։ൃͱίϜΪશήϊϜղੳ΁ͷԠ༻ʯձ, ઍ༿େֶ, ઍ༿, 019 ೥ 3 ݄ 16–17 ೔.
ೋӋ‫ګ‬հ (‫ޱ‬಄ൃද), Ѩ෦஌ࢠ, খᐻࢁಞࢤ, ʮεαϏϊϦͱӅณछͷަࡶ࣮‫ݧ‬ʯ, ೔ຊ૶ྨֶձୈ 43 ճେձ, ‫౎ژ‬େֶ, ‫౎ژ‬, 2019
೥ 3 ݄ 17 ೔.
Ѩ෦஌ࢠ (ট଴ߨԋ), ʮΠΦϯϏʔϜҭछٕज़Ͱເͷ২෺Λ૑Δʯ
, ୈ 6 ճϛχγϯϙʮ‫ػ‬ೳੑόΠΦʯ(TIA ͔͚͸͠‫ڀݚ‬ʮ‫ػ‬ೳੑόΠΦʯάϧʔϓ), ౦‫ژ‬େֶ, ദ, 2019 ೥ 3 ݄ 18 ೔.
ଜాफ‫ޱ( ݠ‬಄ൃද), ౉઒༑ཬ‫ܙ‬, ྛґࢠ, Ѩ෦஌ࢠ, ᅳ෢‫ొٱ‬, ฏ໺ஐ໵, ʮॏΠΦϯϏʔϜরࣹ༤ੑ഑‫͕ࢠۮ‬ॏෳडਫ਼ͱᡢൃੜʹ‫͢΅ٴ‬Ө‫ڹ‬ʯ, Ԃֶܳձฏ੒ 31 ೥౓य़‫ق‬େձ, ໌࣏େֶ, ઒࡚, 2019 ೥ 3 ݄ 23–24 ೔.
ৗઘ࿨ल (‫ޱ‬಄ൃද), ࢁాඒ‫ࢠܙ‬, Ұ੉উ‫ل‬, ࢢా༟೭, ۚᜉ௝, ഡ‫ݪ‬ಞࢤ, ઒ా࣮‫ق‬, ยࢁ‫࢜و‬, 㟒ࢁҰ޹, ख௩৴߂, খүխ඙, Ѩ෦஌ࢠ, ʮॏΠΦϯϏʔϜরࣹʹΑΔγΦϛζπϘϫϜγେ‫ܕ‬มҟ‫ܥ‬౷ͷҭछʯ, ೔ຊ೶ܳԽֶձ 2019 ೥౓େձ, ౦‫ژ‬೶‫ۀ‬େֶ, ੈ
ా୩, 2019 ೥ 3 ݄ 26–27 ೔.
ଜాਔ (‫ޱ‬಄ൃද), ஥໺ᠳଠ, ࢁதߴ࢙, Լ઒஌ࢠ, Ѩ෦஌ࢠ, ࢢా༟೭, ྛґࢠ, ా‫߃ݪ‬, ଠా໌, ʮೋһഓཆ‫ڞͰܥ‬ੜύʔτφʔͷΞΧϚπ࣮ੜබΛ‫ރ‬Β͢Ϛπλέมҟମͷ࡞ग़ʯ, ೔ຊ೶ܳԽֶձ 2019 ೥౓େձ, ౦‫ژ‬೶‫ۀ‬େֶ, ੈా୩, 2019 ೥ 3 ݄ 26–27 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Ѩ෦஌ࢠ (‫ޱ‬಄ൃද), ੴҪެଠ࿠, ෩ؒ༟հ, ฏ໺ஐ໵, ʮॏΠΦϯϏʔϜরࣹʹΑΓ༠ൃͨ͠γϩΠψφζφมҟͷಛ௃ʯ, ‫ૅج‬෺ཧֶ‫ڀݚॴڀݚ‬ձʮ์ࣹઢͷੜମӨ‫ڹ‬ղ໌΁ͷ෼໺ԣஅʹΑΔ௅ઓʯ, ‫౎ژ‬େֶ, ‫౎ژ‬, 2019 ೥ 5 ݄ 23–25 ೔.
ੴҪެଠ࿠ (‫ޱ‬಄ൃද), ࢢా༟೭, Ѩ෦஌ࢠ, ʮΠωͷ඼छಛҟతߴਫ਼౓ϦϑΝϨϯε഑ྻ࡞੡ख๏ͷ։ൃʯ, ೔ຊҭछֶձୈ 136
ճߨԋձ, ۙ‫ـ‬େֶ, ಸྑ, 2019 ೥ 9 ݄ 6–7 ೔.
‫ٱ‬ଜຑࢠ (‫ޱ‬಄ൃද), ॾԬ३࢘, Ѩ෦஌ࢠ, ྛґࢠ, ฏ໺ஐ໵, ʮॏΠΦϯϏʔϜরࣹʹΑΔՆळখΪΫ඼छʮ௕࡚ SWC1ʯͷҭ੒ʯ,೔ຊҭछֶձୈ 136 ճߨԋձ, ۙ‫ـ‬େֶ, ಸྑ, 2019 ೥ 9 ݄ 6–7 ೔.
ઘխࢠ (ϙελʔൃද), Ѩ෦஌ࢠ, ʮॏཻࢠઢʹΑΓ༠ൃ͞ΕΔ DNA ೋຊ࠯੾அͷम෮‫ߏػ‬ͷղੳʯ, ୈ 42 ճ೔ຊ෼ࢠੜ෺ֶձେ
ձ, ෱Ԭࠃࡍձٞ৔ ϚϦϯϝοη෱Ԭ, ෱Ԭ, 2019 ೥ 12 ݄ 3–6 ೔.
Ѩ෦஌ࢠʢট଴ߨԋ), ʮΠΦϯҭछͷ‫ݱ‬ঢ়ͱͦΕͧΕͷࢪઃͷಛ௃ʯ, ෱ҪΠΦϯϏʔϜҭछ‫ڀݚ‬ձ, ए‫ڱ‬࿷ΤωϧΪʔ‫ڀݚ‬ηϯλʔ, ರլ, 2019 ೥ 12 ݄ 13 ೔.
౻ా༔ੜ (‫ޱ‬಄ൃද), ࢢా༟೭, ෩ؒஐ඙, Ѩ෦஌ࢠ, ௗࢁ‫࠸ێ‬, ʮindica ඼छ Lebed ʹ୆த 65 ߸Λ໭͠ަࡶͯ͠ಘΒΕͨ༤ੑෆູ
ੑͷղੳʯ, ࠃཱҨ఻ֶ‫ ॴڀݚ‬Πωଐۙԑछ‫ڀݚ‬ձʮOryza ଐήϊϜ৘ใΛ‫ͨ͠༻׆‬Ҩ఻తଟ༷ੑ‫ڀݚ‬ͷਪਐʯ, ࠃཱҨ఻‫ॴڀݚ‬,ࡾౡ, 2019 ೥ 12 ݄ 12–13 ೔.

Press releases
ࢢా༟೭, Ѩ෦஌ࢠ, ʮޮ཰తͳ൓෮഑ྻআ‫ٕڈ‬ज़ͷ։ൃͱίϜΪશήϊϜղੳ΁ͷԠ༻ʯ, ೔ຊҭछֶձ 2019 ೥य़‫ق‬େձʢ135ճʣઍ༿େֶ ‫ൃऀه‬ද, 2019 ೥ 3 ݄ 7 ೔.
੩Ԭ‫ݝ‬, ʮ৽඼छʮS1200ʯ΁ͷ‫ظ‬଴ʯ, ੩Ԭ‫ݝ‬೶ྛٕज़‫ॴڀݚ‬, ‫ॴڀݚ‬χϡʔε 58, 2019 ೥ 8 ݄.
‫ٱ‬ଜຑࢠ, ॾԬ३࢘, Ѩ෦஌ࢠ, ྛґࢠ, ฏ໺ஐ໵, ʮॏΠΦϯϏʔϜ঎ࣾʹΑΔՆळখΪΫ඼छʮ௕࡚ SWC1ʯͷҭ੒ʯ, ೔ຊҭछ
ֶձ 2019 ೥ळ‫ق‬େձʢ136 ճʣ, ۙ‫ـ‬େֶ ‫ൃऀه‬ද, 2019 ೥ 9 ݄ 3 ೔.

PatentsѨ෦஌ࢠ, ৿ాཽฏ, ྛґࢠ, ࢢా༟೭, ҆෦߂, ࠤ౻խࢤ, ʮछࢠͷαΠζ͕૿େͨ͠২෺ͷ੡଄ํ๏ʯ, ಛ‫ڐ‬ग़‫ئ‬൪߸ 2019-000749,
ग़‫ئ‬೔ 2019 ೥ 1 ݄ 7 ೔.
Ѩ෦஌ࢠ, ৗઘ࿨ल, ࢢా༟೭, ഡ‫ݪ‬ಞࢤ, ΩϜɾώδϯ, ࡕ૔ྑ޹, ੁ޲ࢤ࿠, খүխ඙, ख௩৴߂, ઒ా࣮‫ق‬, খྛ‫ܟ‬య, ʮϫϜγͷมҟ‫ܥ‬౷ͷ࡞ग़ํ๏, ϫϜγͷมҟ‫ܥ‬౷, ͓ΑͼॏΠΦϯϏʔϜͷ൑ఆํ๏ʯಛ‫ڐ‬ग़‫ئ‬൪߸ 2019-015899, ग़‫ئ‬೔ 2019 ೥ 1 ݄ 31 ೔.
‫ٱ‬ଜຑࢠ, ॾԬ३࢘, Ѩ෦஌ࢠ, ྛґࢠ, ฏ໺ஐ໵, ʮΩΫ඼छ’ ௕࡚ SWC1’ʯ, ඼छొ࿥ग़‫ئ‬൪߸ 33790, ग़‫ئ‬೔ 2019 ೥ 3 ݄ 18 ೔.
མ߹੒ޫ, Ѩ෦஌ࢠ, ྛґࢠ, ʮϋΠϏεΧε඼छ’ ϚβʔΦϨϯδ’ʯ, ඼छొ࿥ग़‫ئ‬൪߸ 33885, ग़‫ئ‬೔ 2019 ೥ 4 ݄ 22 ೔.

Outreach activitiesѨ෦஌ࢠ, ࢢా༟೭, ࢁాඒ‫ࢠܙ‬, ʮॏΠΦϯϏʔϜʹ཮্ཆ৩, ʮϫΧϝͷֵ৽ʯਐΉʯ೔ຊͷԑਂ͖ւ૶, ͦͷྺ࢙ͱ‫ࡏݱ‬ʢ‫ޙ‬ฤʣ, https://jbpress.ismedia.jp/articles/-/55473, ࣫‫࣍ݪ‬࿠ʢ‫ऀه‬ʣ, ‫ݱ‬୅Ϗδωε, ৯ͷ‫ॴڀݚ‬, 2019 ೥ 2 ݄ 15 ೔.
https://www.foods-ch.com/shokuhin/1556092438588/, ϑʔζνϟωϧ, 2019 ೥ 4 ݄ 25 ೔ʢసࡌʣ
We established the “Asagao (Morning glory) Club” to deepen the understanding of our technology of mutation breeding. The club
distributes the morning glory seeds irradiated with C-ion on request, and collects and compiles the observation reports of their growth.
Some reports have been featured in the booklet issued by the club every two years.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Accelerator Applications Research Division
Beam Mutagenesis Group
Plant Genome Evolution Research Team
1. Abstract
Established in May 2018, the plant genome evolution research team studies the eﬀect of heavy-ion induced mutations on plant
phenotypes. Chromosome rearrangements including translocation, inversion, and deletion are thought to play an important role inevolution and have a great potential to provide large phenotypic changes. However, this potential has not been fully investigated because of the lack of an eﬀective method to induce rearrangements. We recently found that chromosomal rearrangements are frequently
induced after heavy-ion irradiations with high valence numbers such as Fe ions or Ar ions. This frequency is 30 times higher thanthat of the previous techniques and allows characterization of the eﬀect of chromosomal rearrangements. We develop amd optimize
molecular and bioinfoematics techniquws based on the resent progress on genome sequencing technology, to eﬃciently identify andanalyse genomic mutations from model and non-model plant species. we also utilise this heavy-ion’s unique capability for plant
breeding and evolution studies.

2. Major Research Subjects(1) Study on the eﬀect of chromosomal rearrangements on plant genomes and phenotypes(2) Identification of the plant sex-determining genes and their evolutionary study

3. Summary of Research Activity(1) Study on the eﬀect of chromosomal rearrangements on plant genomes and phenotypes
In order to investigate the eﬀect of chromosome rearrangements on plant phenotypes, we analysed the Arabidopsis mutant Ar55as1, which were originally induced by Ar-beam irradiation at a dose of 50 Gy with an LET of 290 keV/µm. This mutant has no
homozygous mutation in any genes but has chromosomal rearrangements in the genome. This mutant shows a clear morphologicalmutant phenotype in which the petiole is shorter than wild-type plants. As a result of the investigation of the trait of each individual
and the presence or absence of chromosome rearrangements in the M3 generation of the mutant, we found that the inversion ofchromosome 2 is responsible for the phenotype. In addition, this inversion was found to be a dominant mutation. From this finding,we showed that a chromosome rearrangement can dominantly aﬀect the plant phenotype. We are currently investigating the eﬀect of
this inversion on gene expression.
We also attempted to induce a chromosome rearrangement at a target position by using genome editing technology, because thistechnique will be necessary when the functional analysis of chromosomal rearrangements will be performed in the future. There has
been no report in which a large chromosomal rearrangement was induced in A. thaliana by the genome editing. However, we expectedthat if it is a proven chromosomal region where chromosome rearrangement has occurred by heavy-ion irradiation, it can be induced
even when using genome editing. As a result, 760-kb inversion or deletion was successfully induced by genome editing.
(2) Identification of the plant sex-determining genes and their evolutionary study
A dioecious plant, Silene latifolia, has heteromorphic sex chromosomes (X and Y). We previously identified sex changing mutantsof S. latifolia by heavy-ion mutagenesis. The sex-changing mutants include hermaphroditic mutants and asexual mutants. The former
has both stamens and gynoecium, while the latter have no reproductive organs. By whole-genome analysis and RNA seq analysis, wehave idetified a gene that is deleted in all 14 of the 14 hermaphroditic mutants. This gene could be a candidate of sex determinant genewith gynoecium suppressing function.

Members
Team Leader
Tomoko ABEContract Researcher
Kotaro ISHII
Visiting Scientists
Ali FERJANI (Tokyo Gakugei Univ.)

Yusuke KAZAMA (Fukui Prefectural Univ.)

Student Trainees
Andi M. OKASA (Tohoku Univ.)
Part-time Worker
Yukako ABE (Part-time Worker)- 340 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

List of Publications & Presentations
Publications[Original papers]
N. Fujita, Y. Kazama, N. Yamagishi, K. Watanabe, S. Ando, H. Tsuji, S. Kawano, N. Yoshikawa, and K. Komatsu, “Development of the
VIGS system in the dioecious plant Silene latifolia,” Int. J. Mol. Sci. 20, 1031 (2019).
M. Krasovec, Y. Kazama, K. Ishii, T. Abe, and D. A. Filatov, “Immediate dosage compensation is triggered by the deletion of Y-linked
genes in Silene latifolia,” Current Biol. 29, 2214–2221 (2019).
R. Morita, H. Ichida, K. Ishii, Y. Hayashi, H. Abe, Y. Shirakawa, K. Ichinose, K. Tsuneizumi, T. Kazama, K. Toriyama, T. Sato, and
T. Abe, “LONG GRAIN 1: a novel gene that regulates grain length in rice,” Mol. Breed. 39, 135 (2019).
H. Kawamoto, K. Yamanaka, A. Koizumi, K. Ishii, Y. Kazama, T. Abe, and S. Kawano, “An asexual flower of Silene latifolia andMicrobotryum lychnidis-dioicae promotes sex-organ development,” PLoS One 14, e0217329 (2019).

Presentations[International conferences/workshops]
K. Ishii, Y. Kazama, T. Hirano, T. Takeshita, S. Kawano, and T. Abe (poster), “Development of a pipeline for whole-genome mutational
analysis and its application on heavy-ion mutagenesis,” Rice Functional Genomics Workshop in XXVII Plant & Animal Genome
Conference, San Diego, USA, January 12–16, 2019.
T. Abe (invited), H. Ichida, Y. Hayashi, Y. Shirakawa, K. Ishii, and R. Morita, “Ion-beam radiation mutagenesis and plant mutation
breeding,” 14th Conference of Society for the Advancement of the Breeding Research in Asia and Oceania, Gwangju, Korea, July 2–5,
2019.

[Domestic conferences/workshops]෩ؒ༟հ (ট଴ߨԋ), “Study of plant sex chromosome by using heavy-ion induced mutants,” ୈ 1 ճ ॏɾΫϥελʔΠΦϯϏʔϜར༻ʹΑΔඍੜ෺༝དྷߴੜ࢈ੑΤωϧΪʔ, ‫ڥ؀‬γϯϙδ΢Ϝ, ஜ೾େֶ, ͭ͘͹, 2019 ೥ 1 ݄ 29 ೔.
্ా७ฏ, ෩ؒ༟հ, Ѩ෦஌ࢠ, ଜҪߞೋ (‫ޱ‬಄ൃද), ʮҰཻ‫ܥ‬ίϜΪ DV92 ‫ܥ‬౷ʹ͓͚ΔՖ੒஗Ԇมҟମ late-heading 2ʙ5 (l h2ʙ5) ͷಉఆʯ, ೔ຊҭछֶձ ୈ 135 ճߨԋձ, ઍ༿େֶ, ઍ༿ࢢ, 2019 ೥ 3 ݄ 16–17 ೔.
Ѩ෦஌ࢠ, ੴҪެଠ࿠, ෩ؒ༟հ, ฏ໺ஐ໵ (‫ޱ‬಄ൃද), ʮॏΠΦϯϏʔϜরࣹʹΑΓ༠ൃͨ͠γϩΠψφζφมҟͷಛ௃ʯ, ‫ૅج‬෺ཧֶ‫ڀݚॴڀݚ‬ձʮ์ࣹઢͷੜମӨ‫ڹ‬ղ໌΁ͷ෼໺ԣஅʹΑΔ௅ઓʯ, ‫౎ژ‬େֶ, ‫౎ژ‬, 2019 ೥ 5 ݄ 23–25 ೔.
ੴҪެଠ࿠, ࢢా༟೭, Ѩ෦஌ࢠ (ϙελʔൃද), ʮΠωͷ඼छಛҟతߴਫ਼౓ϦϑΝϨϯε഑ྻ࡞੡ख๏ͷ։ൃʯ, ೔ຊҭछֶձୈ
136 ճߨԋձ, ۙ‫ـ‬େֶ, ಸྑ, 2019 ೥ 9 ݄ 6–7 ೔.
෩ؒ༟հ, M. Krasovec, ੴҪެଠ࿠, Ѩ෦஌ࢠ, D. A. Filatov (‫ޱ‬಄ൃද), ʮࣁ༤ҟ‫ג‬২෺ώϩϋϊϚϯςϚͰൃ‫ͨ͠ݟ‬ੑછ৭ମͷଈ࣌Ҩ఻ࢠྔิਖ਼ʯ, ೔ຊҨ఻ֶձ 91 ճେձ, ෱Ҫେֶ, ෱Ҫ, 2019 ೥ 9 ݄ 11–14 ೔.
‫ڮ‬ຊՂ੅, ੢ӜѪࢠ, ্ా७ฏ, ෩ؒ༟հ, ࢢా༟೭, Ѩ෦஌ࢠ, ଜҪߞೋ (ϙελʔൃද), ʮॏΠΦϯϏʔϜʹΑͬͯ࡞ग़͞Εͨ௒‫ૣۃ‬ੜίϜΪมҟମ extra early-flowering 4 ʹ͓͚Δ‫ݪ‬ҼҨ఻ࢠͷಉఆʯ, ೔ຊҨ఻ֶձ 91 ճେձ, ෱Ҫେֶ, ෱Ҫ, 2019 ೥ 9 ݄
11–14 ೔.
ञҪਹਓ, ฏాઍᜢ, ෩ؒ༟հ, Ѩ෦஌ࢠ, ࡾଜప࿠, ਂ৓ӳ߂, ੴ࡚ެ߁ (ϙελʔൃද), ʮॏΠΦϯϏʔϜরࣹ๔ࢠΛ༻͍ͨθχΰέ഑‫ۮ‬ମ‫ܗ‬ଶ‫ܗ‬੒มҟମͷεΫϦʔχϯάͱղੳʯ, ೔ຊ২෺ֶձ 83 ճେձ, ౦๺େֶ, ઋ୆ࢢ, 2019 ೥ 9 ݄ 15–17 ೔.
౉ᬑང, େ෦੅ߐ, Ѩ෦஌ࢠ, ෩ؒ༟հ (ϙελʔൃද), ʮήϊϜฤूʹΑΔγϩΠψφζφ΁ͷછ৭ମ࠶ฤ੒ͷಋೖʯ, ೔ຊ২෺ֶ
ձ 83 ճେձ, ౦๺େֶ, ઋ୆, 2019 ೥ 9 ݄ 15–17 ೔.
෩ؒ༟հ (‫ޱ‬಄ൃද), ʮછ৭ମ࠶ฤ੒: ͦͷ༠ൃͱද‫ʹܕݱ‬༩͑ΔӨ‫ڹ‬ʯ, ୈ 12 ճ๺཮߹ಉόΠΦγϯϙδ΢Ϝ, ਗ਼෩૳, ͋ΘΒ,2019 ೥ 10 ݄ 25–26 ೔.
্ా७ฏ, ෩ؒ༟հ, Ѩ෦஌ࢠ, ࢢా༟೭, ଜҪߞೋ (ϙελʔൃද), ʮҰཻ‫ܥ‬ίϜΪ (Triticum monococcum) KU104-2 ͓Αͼ DV92‫ܥ‬౷͔Β࡞ग़ͨ͠Ֆ੒஗Ԇมҟମ late-heading1, 2 (l h1, 2) ͷղੳʯ, ୈ 14 ճϜΪྨ‫ڀݚ‬ձ, ௗऔେֶ‫ס‬૩஍‫ڀݚ‬ηϯλʔ, ௗऔ,2019 ೥ 11 ݄ 2–3 ೔.
‫ڮ‬ຊՂ੅, ੢ӜѪࢠ, ্ా७ฏ, ෩ؒ༟հ, Ѩ෦஌ࢠ, ࢢా༟೭, ଜҪߞೋ (ϙελʔൃද), ʮॏΠΦϯϏʔϜরࣹʹΑͬͯ࡞ग़͞Εͨ௒‫ૣۃ‬ੜίϜΪมҟମ extra early-flowering 4 ʹ͓͚Δ‫ݪ‬ҼҨ఻ࢠͷಉఆʯ, ୈ 14 ճϜΪྨ‫ڀݚ‬ձ, ௗऔ, ௗऔେֶ‫ס‬૩஍‫ڀݚ‬ηϯλʔ, 2019 ೥ 11 ݄ 2–3 ೔.
ߴ৓‫ܒ‬Ұ, ੴҪެଠ࿠, ാԼণൣ, Ѩ෦஌ࢠ (ϙελʔൃද), ʮATM/ATR ‫ػ‬ೳܽଛγϩΠψφζφࠜ୺ʹ͓͚Δ X ઢরࣹ‫ޙ‬ͷ
γ-H2AX ͷۭ࣌ؒؒ෼෍ʯ, ೔ຊ์ࣹઢӨ‫ֶڹ‬ձୈ 62 ճେձ, ‫౎ژ‬େֶ, ‫౎ژ‬, 2019 ೥ 11 ݄ 14–16 ೔.
෩ؒ༞հʢট଴ߨԋ), ʮ෱Ҫ‫ཱݝ‬େֶʹ͓͚ΔΠΦϯҭछͷల๬—Ԃܳ২෺ͷછ৭ମ࠶ฤ‫ڀݚ‬ʯ, ෱ҪΠΦϯϏʔϜҭछ‫ڀݚ‬ձ, ए‫ڱ‬࿷ΤωϧΪʔ‫ڀݚ‬ηϯλʔ, ರլ, 2019 ೥ 12 ݄ 13 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Accelerator Applications Research Division
RI Application Research Group
1. Abstract
RI Application Research Group promotes industrial applications of radioisotopes (RI) and ion beams at RIKEN RI Beam Factory(RIBF). Nuclear Chemistry Research Team develops production technologies of useful RIs for application studies in nuclear andradiochemistry. The team also develops technologies of mass spectrometry for trace-element and isotope analyses and apply themto the research fields such as cosmochemistry, environmental science, archaeology, and so on. Industrial Application Research Team
promotes industrial applications of the accelerator facility and its related technologies.

2. Major Research Subjects(1) Research and development of RI production technologies at RIBF
(2) RI application researches(3) Development of trace element analyses using accelerator techniques and its application to geoscience and archaeologicalresearch fields(4) Development of chemical materials for ECR ion sources of the RIBF accelerators(5) Development of technologies on industrial utilization and novel industrial applications of RIBF
(6) Support of industrial utilization of the heavy-ion beams at RIBF
(7) Support of some materials science experiments(8) Fee-based distribution of RIs produced at RIBF

3. Summary of Research Activity
See the subsections of Nuclear Chemistry Research Team and Industrial Application Research Team.

Members
Director
Hiromitsu HABATeam Leaders
Hiromitsu HABA

Atsushi YOSHIDA

List of Publications & Presentations
See the subsections of Nuclear Chemistry Research Team and Industrial Application Research Team- 342 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Accelerator Applications Research Division
RI Application Research Group
Nuclear Chemistry Research Team
1. Abstract

The Nuclear Chemistry Research Team develops production technologies of unique radioisotopes (RIs) at RIKEN RI Beam
Factory (RIBF) and applies them in the research fields of physics, chemistry, biology, engineering, medicine, pharmaceutical andenvironmental sciences. The purified RIs such as 65 Zn, 67 Cu, 85 Sr, 88 Y, and 109 Cd are delivered to universities and institutes throughJapan Radioisotope Association. We also develop new technologies of mass spectrometry for the trace-element analyses using accelerator technology and apply them to the research fields such as cosmochemistry, environmental science, archaeology, and so on. We
perform various isotopic analyses on the elements such as S, Pd, and Pb using ICP-MS, TIMS, and IRMS. We also develop chemicalmaterials for ECR ion sources of the heavy-ion accelerators at RIBF.

2. Major Research Subjects(1) Research and development of RI production technologies at RIBF
(2) RI application researches(3) Development of trace element analyses using accelerator techniques and its application to geoscience and archaeologicalresearch fields(4) Development of chemical materials for ECR ion sources of the heavy-ion accelerators at RIBF

3. Summary of Research Activity(1) Research and development of RI production technologies at RIBF and RI application researches
Due to its high sensitivity, the radioactive tracer technique has been successfully applied for investigations of the behavior ofelements in the fields of chemistry, biology, engineering, medicine, pharmaceutical and environmental sciences. We have been developing production technologies of useful radiotracers at RIBF and conducting their application studies in collaboration with many
researchers in various fields. With 30-MeV proton, 24-MeV deuteron, and 50-MeV alpha beams from the AVF cyclotron, we presently
produce about 100 radiotracers from 7 Be to 211 At. Among them, 65 Zn, 67 Cu, 85 Sr, 88 Y, and 109 Cd are delivered to Japan Radioisotope
Association for fee-based distribution to the general public in Japan. Our RIs are also distributed to researchers under the Supply
Platform of Short-lived Radioisotopes for Fundamental Research, supported by MEXT KAKENHI. On the other hand, radionuclides
of a large number of elements are simultaneously produced from metallic targets such as nat Ti, nat Ag, nat Hf, 197 Au, and 232 Th irradiatedwith a 135-MeV nucl.−1 14 N beam from the RIKEN Ring Cyclotron. These multitracers are also supplied to universities and institutes
as collaborative researches.
In 2019, we developed production technologies of radioisotopes such as 24 Na, 42, 43 K, 44m Sc, 48 Cr, 111 Ag, 186 Re, 211 At, 224 Ra,
212
Pb, and 225 Ac which were strongly demanded but lack supply sources in Japan. We also investigated the excitation functions
for the nat V(p, x), nat Cr(p, x), nat La(p, x), 169 Tm(p, x), nat Ta(p, x), 45 Sc(d, x), nat Tl(d, x), nat Ca(α, x), nat Ni(α, x), nat Sb(α, x),nat Nd(α, x),nat
Gd(α, x), and nat Dy(α, x) reactions to quantitatively produce useful RIs. We used radiotracers of 42, 43 K, 44m Sc, 111 Ag, 186 Re, 211 At,
224
Ra, 212 Pb, and 225 Ac for application studies in chemistry, 24 Na, 42, 43 K, 44m Sc, 67 Cu, 186 Re, 211 At, and 225 Ac in nuclear medicine.
We also produced 65 Zn, 67 Cu, and 88 Y for our scientific researches on a regular schedule and supplied the surpluses through Japan
Radioisotope Association to the general public. In 2019, we accepted 2 orders of 65 Zn with a total activity of 6.7 MBq, 1 order of67
Cu with 5 MBq, and 2 orders of 88 Y with 2 MBq. We also distributed 44m Sc (2 MBq × 3), 88 Zr (1 MBq × 1 and 2 MBq × 1), 95 Nb(1 MBq × 2 and 2 MBq × 1), 124 Sb (2 MBq × 1), 141 Ce (9 kBq × 1 and 13 kBq × 1), 175 Hf (1 MBq × 1 and 2 MBq × 1), and 211 At(5 MBq × 4, 50 MBq × 6, 100 MBq × 11, and 120 MBq × 1) under the Supply Platform of Short-lived Radioisotopes for Fundamental
Research.
(2) Superheavy element chemistry
Chemical characterization of newly-discovered superheavy elements (SHEs, atomic numbers Z ≥ 104) is an extremely interesting and challenging subject in modern nuclear and radiochemistry. We are developing SHE production systems as well as rapid
single-atom chemistry apparatuses at RIBF. Using heavy-ion beams from RILAC and AVF, 261 Rf (Z = 104), 262 Db (Z = 105),265
Sg (Z = 106), and 266 Bh (Z = 107) are produced in the 248 Cm(18 O, 5n)261 Rf, 248 Cm(19 F, 5n)262 Db, 248 Cm(22 Ne, 5n)265 Sg, and248
Cm(23 Na, 5n)266 Bh reactions, respectively, and their chemical properties are investigated.
We installed a gas-jet transport system to the focal plane of the gas-filled recoil ion separator GARIS at RILAC. This system isa promising approach for exploring new frontiers in SHE chemistry: the background radiations from unwanted products are strongly
suppressed, the intense primary heavy-ion beam is absent in the gas-jet chamber, and hence the high gas-jet extraction yield is attained.
Furthermore, the beam-free condition makes it possible to investigate new chemical systems. To realize aqueous chemistry studies of
Sg and Bh, we have been developing a continuous and rapid solvent extraction apparatus which consists of a continuous dissolution
apparatus Membrane DeGasser (MDG), a Flow Solvent Extractor (FSE), and a liquid scintillation detector for α/SF-spectrometry.
On the other hand, we have a gas-jet coupled target system and a safety system for a radioactive 248 Cm target on the beam lineof AVF. In 2019, the distribution coeﬃcients of 261 Rf on the anion-exchange resin in the H2 SO4 system were measured with the
AutoMated Batch-type solid-liquid Extraction apparatus for Repetitive experiments of transactinides (AMBER) which was developedby the research group of Osaka University. The distribution coeﬃcients of 262 Db on the anion-exchange resin in the mixed HF/HNO3- 343 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

system were also measured with the Automated Rapid Chemistry Apparatus (ARCA) of Japan Atomic Energy Agency. We produced
radiotracers of 88 Zr, 95 Nb, 95m Tc, 175 Hf, 177, 179 Ta, and 183 Re at AVF and conducted model experiments for aqueous chemistry studies
on Rf, Db, and Bh. In 2019, we developed a cryogenic RF-carpet gas cell, which will be placed on the focal plane of GARIS andconnected to a gas chromatographic apparatus, for the future gas-phase chemistry of the short-lived SHEs (<3 s).
(3) Development of trace element analyses using accelerator techniques and its application to geoscience and archaeologicalresearch fields
We have been developing the ECR Ion Source Mass Spectrometer (ECRIS-MS) for trace element analyses. In 2019, we renovatedthe detection system of ECRIS-MS and evaluated its sensitivity and mass resolution power. We equipped a laser-ablation system with
an ion source and a pre-concentration system to achieve high-resolution analyses for noble gases such as Kr and Xe.
Using the conventional ICP-MS, TIMS, IRMS, and so on, we analyzed sediments such as a ferro-manganese nodule in the Pacific
Ocean to elucidate its growth history concerning the environmental changes in the ocean. We also studied Pb and S isotope ratios on
cinnabar and asphalt samples from ancient ruins in Japan to elucidate the distribution of goods in the archaic society and to reveal
the establishment of the Yamato dynasty in the period from Jomon to Tumulus. We established a sampling technique for pigment
without any damages on the artifacts or wall paintings, using a S-free adhesive tape. Then, we applied the technique to the analyses ofthe pigment from Roman ruins in Badalona, Spain. We also applied the technique to the analyses of the red-color substances on theartifacts such as Kyoden remains (Izumo-city, Shimane prefecture), Renpeijou-ato (Zentuji-city, Kagawa prefecture) and so on. We
also investigated the transmutation of the long-lived 107 Pd to the stable Pd isotopes by the deuteron-induced nuclear reaction.
(4) Development of chemical materials for ECR ion sources of the heavy-ion accelerators at RIBF
In 2019, we prepared metallic 238 U rods and 238 UO2 on a regular schedule for 238 U-ion accelerations with the 28-GHz ECR of
RILAC II.

Members
Team Leader
Hiromitsu HABA
Research/Technical Scientist
Kazuya TAKAHASHI (Senior Research Scientist)
Research & Development Scientist
Hiroo HASEBE
Contract Researcher
Yukiko KOMORISpecial Postdoctoral Researcher
Yudai SHIGEKAWA
Postdoctoral Researchers
Yang WANG

Takuya YOKOKITA

Technical Staﬀ I
Daiki MORI
Research Consultant
Hisaaki KUDO (Niigata Univ.)
Visiting Scientists
Masayuki AIKAWA (Hokkaido Univ.)
Kazuhiko AKIYAMA (Tokyo Metropolitan Univ.)
Ferenc DITRÓI (ATOMKI)
Osuke FUJIMOTO (Fujifilm Toyama Chemical Co., Ltd.)
Takahiro HIRAKI (Okayama Univ.)
Hayato IKEDA (Tohoku Univ.)
Noriko ISHIOKA (QST)
Masamichi KAJITA (Fujifilm Toyama Chemical Co., Ltd.)
Hiroshi KATO (Fujifilm Toyama Chemical Co., Ltd.)
Mayeen U. KHANDAKER (Sunway Univ.)
Hidetoshi KIKUNAGA (Tohoku Univ.)
Yoshikatsu KOGA (Nat’l Cancer Center)
Shoko KUBOTA (Fujifilm Toyama Chemical Co., Ltd.)
Takumi KUBOTA (Kyoto Univ.)

Susanta Kumar LAHIRI (Saha Inst. of Nucl. Phys.)
Takahiko MASUDA (Okayama Univ.)
Toshimitsu MOMOSE (Int’l Univ. of Health and Welfare)
Akio NAGANO (Fujifilm Toyama Chemical Co., Ltd.)Eri NAKAMURA (Fujifilm Toyama Chemical Co., Ltd.)
Kenichiro OGANE (Int’l Univ. of Health and Welfare)
Miki OHTSUKA (Waseda Univ.)
Kazuhiro OOE (Osaka Univ.)
Shinobu OSHIKIRI (Fujifilm Toyama Chemical Co., Ltd.)
Yasutaka SAITO (Fujifilm Toyama Chemical Co., Ltd.)Aya SAKAGUCHI (Univ. of Tsukuba)
Miho SATAKE (Fujifilm Toyama Chemical Co., Ltd.)
Yuki SATO (Fujifilm Toyama Chemical Co., Ltd.)
Kenji SHIMAZOE (Univ. of Tokyo)- 344 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Keisuke SUEKI (Univ. of Tsukuba)
Kentaro SUZUKI (Fujifilm Toyama Chemical Co., Ltd.)
Zoltán SZŰCS (ATOMKI) Sándor TAKÁCS (ATOMKI)
Hiroyuki TAKAHASHI (Univ. of Tokyo)
Miho TAKAHASHI (Tokyo Univ. of Marine Sci. and Tech.)
Miwako TAKAHASHI (Nat’l Inst. of Radiological Sci.)
Yuichi TAKAKU (Inst. for Environmental Sci.)
Hiroki TAKASHIMA (Nat’l Cancer Center)
Kazuo TANAKA (Tohoku Univ.)
Masayoshi TODA (Tokyo Univ. of Marine Sci. and Tech.)
Visiting Technicians
Hideyuki ARAI (Metal Tech. Co. Ltd.)
Hiroshi ARATA (Metal Tech. Co. Ltd.)
Hidehiro HASHIMOTO (Metal Tech. Co. Ltd.)
Yoshiyuki IIZUKA (ATOX Co., Ltd.)
Akimitsu KANDA (Japan Radioisotope Association)
Shota KIMURA (Japan Radioisotope Association)
Yukiyoshi KON (Osaka Univ.)
Takashi KURIHARA (Metal Tech. Co. Ltd.)

Atsushi TOYOSHIMA (Osaka Univ.)
Takashi UI (Fujifilm Toyama Chemical Co., Ltd.)
Naoyuki UKON (Fukushima Medical Univ.)
Ahmed R. USMAN (Umaru Musa Yar’adua Univ.)
Shigeki WATANABE (QST)
Chunli YANG (Inst. of Modern Phys.)
Akihiko YOKOYAMA (Kanazawa Univ.)
Zenko YOSHIDA (ATOX Co., Ltd.)
Koji YOSHIMURA (Okayama Univ.)

Takahiro MIKAMOTO (Japan Radioisotope Association)
Hiroki SHIBAHARA (ATOX Co., Ltd.)
Yuki TAKEMURA (ATOX Co., Ltd.)
Yasutaka TAKEUCHI (ATOX Co., Ltd.)
Shusaku TAZAWA (ATOX Co., Ltd.)
Yuichirou WAKITANI (Japan Radioisotope Association)
Mami YUKI (ATOX Co., Ltd.)

Student Trainees
Sadia ADACHI (Univ. of Tsukuba)
Kjeld A. A. G. BEEKS (Vienna Univ. of Tech.)
Desheng CHEN (Univ. of Chinese Academy of Sci.)
Wei Seng FOONG (Univ. of Tokyo)
Yuta HAYAKAWA (Kanazawa Univ.)
Sho HAYAMI (Osaka Univ.)
Xuan HOU (Univ. of Tokyo)
Ayuna KASHIHARA (Univ. of Tsukuba)
Mizuho KATO (Univ. of Tsukuba)
Cheonghun KIM (Univ. of Tokyo)
Mariko KOBAYASHI (Univ. of Tokyo)
Masaharu KURINO (Univ. of Tokyo)
Natsuki MATSUMURA (Kanazawa Univ.)
Ryoga MORITA (Kanazawa Univ.)
Tomohiro MURATA (Hokkaido Univ.)

Akihisa NAKAJIMA (Univ. of Tsukuba)
Kaito NISHIZUKA (Univ. of Tsukuba)
Koichi OKAI (Okayama Univ.)
Moemi SAITO (Hokkaido Univ.)
Michiya SAKAGUCHI (Hokkaido Univ.)
Kaori SHIRAI (Niigata Univ.)
Hayato SUZUKI (Ibaraki Univ.)
Yusuke SUZUKI (Univ. of Tsukuba)
Kakeru TERANISHI (Kanazawa Univ.)
Katsuyuki TOKOI (Ibaraki Univ.)
Katsuma TONAI (Osaka Univ.)
Mizuki UENOMACHI (Univ. of Tokyo)
Eisuke WATANABE (Osaka Univ.)
Yuki YASUDA (Osaka Univ.)
Zhihong ZHONG (Univ. of Tokyo)

Part-time Workers
Michiko KITAGAWA (Research Part-time Worker I)
Nozomi SATO (Research Part-time Worker I)

Sachiko USUDA (Research Part-time Worker I)
Minako OSANAI (Research Part-time Worker II)

List of Publications & Presentations
Publications[Original papers]
M. Aikawa, M. Saito, Y. Komori, H. Haba, S. Takács, F. Ditrói, and Z. Szűcs, “Activation cross sections of alpha-particle induced nuclear
reactions on natural palladium,” Nucl. Instrum. Methods Phys. Res. B, 449, 99–104 (2019).
E. Corniani, F. Ditrói, S. Takács, H. Haba, Y. Komori, M. Aikawa, M. Saito, and T. Murata, “Study of secondary implantation ofradioisotopes during alpha-particle irradiation,” J. Radioanal. Nucl. Chem. 320, 813–822 (2019).
M. Saito, M. Aikawa, T. Murata, N. Ukon, Y. Komori, H. Haba, and S. Takács, “Activation cross sections of alpha-induced reactions on
natural ytterbium upto 50 MeV,” Nucl. Instrum. Methods Phys. Res. B 453, 15–21 (2019).
M. Ebihara, Y. Oura, N. Shirai, Y. Nagakawa, N. Sakurai, H. Haba, H. Matsuzaki, H. Tsuruta, and Y. Moriguchi, “A new approachfor reconstructing the 131 I-spreading due to the 2011 Fukushima nuclear accident by means of measuring 129 I in airborne particulatematters,” J. Environ. Radio. 208-209, 106000-1–9 (2019).
T. Masuda, A. Yoshimi, A. Fujieda, H. Fujimoto, H. Haba, H. Hara, T. Hiraki, H. Kaino, Y. Kasamatsu, S. Kitao, K. Konashi, Y. Miyamoto,
K. Okai, S. Okubo, N. Sasao, M. Seto, T. Schumm, Y. Shigekawa, K. Suzuki, S. Stellmer, K. Tamasaku, S. Uetake, M. Watanabe,
T. Watanabe, Y. Yasuda, A. Yamaguchi, Y. Yoda, T. Yokokita, M. Yoshimura, and K. Yoshimura, “X-ray pumping of the 229 Th nuclear
clock isomer,” Nature 573, 238–242 (2019).
M. Saito, M. Aikawa, M. Sakaguchi, N. Ukon, Y. Komori, and H. Haba, “Production cross sections of ytterbium and thulium radioisotopes
in alpha-induced nuclear reactions on natural erbium,” Appl. Radiat. Isot. 154, 108874-1–6 (2019).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Y. Shigekawa, Y. Kasamatsu, E. Watanabe, H. Ninomiya, S. Hayami, N. Kondo, Y. Yasuda, H. Haba, and A. Shinohara, “Observation ofinternal-conversion electrons emitted from 229m Th produced by beta decay of 229 Ac,” Phys. Rev. C 100, 044304-1–7 (2019).
A. Yamaguchi, H. Muramatsu, T. Hayashi, N. Yuasa, K. Nakamura, M. Takimoto, H. Haba, K. Konashi, M. Watanabe, H. Kikunaga,
K. Maehata, N. Y. Yamasaki, and K. Mitsuda, “Energy of the 229 Th nuclear clock isomer determined by absolute γ-ray energy diﬀerence,” Phys. Rev. Lett. 123, 222501-1–6 (2019).
T. Murata, M. Aikawa, M. Saito, H. Haba, Y. Komori, N. Ukon, S. Takács, and F. Ditrói, “Excitation function measurement for zirconium89 and niobium-90 production using alpha-induced reactions on yttrium-89,” Nucl. Instrum. Methods Phys. Res. B 458, 21–27 (2019).
S. Takács, M. Aikawa, M. Saito, T. Murata, N. Ukon, Y. Komori, and H. Haba, “Activation cross sections of alpha particle-induced
reactions on natural hafnium up to 50 MeV”, Nucl. Instrum. Methods Phys. Res. B 459, 50–58 (2019).
D. Ichinkhorloo, M. Aikawa, T. Zolbadral, Y. Komori, and H. Haba, “Activation cross sections of dysprosium-157, 159 and terbium-160
radioisotopes from the deuteron-induced reactions on terbium-159 up to 24 MeV,” Nucl. Instrum. Methods Phys. Res. B 461, 102–104(2019).
T. Minami, K. Hatanaka, Y. Motizuki, Y. Nakai, and K. Takahashi, “A method of collecting trace amounts of vermilion from artifacts forsource estimation by sulfur isotope (δ34 S) analysis: Use of sulfur-free adhesive tape to minimize damage to the artifact body during
sampling,” J. Archaeolog. Sci. Rep. 28, 102027-1–5 (2019).
A. R. Usman, M. U. Khandaker, H. Haba, N. Otuka, and M. Murakami, “Production cross sections of thulium radioisotopes for alphaparticle induced reactions on holmium,” Nucl. Instrum. Methods Phys. Res. B 469, 42–48 (2020).
M. Okamura, E. Beebe, S. Ikeda, T. Kanesue, D. Raparia, T. Karino, and H. Haba, “96 Zr beam production for isobar experiment inrelativistic heavy ion collider,” Rev. Sci. Instrum. 91, 013319-1–5 (2020).
T. Tanaka, K. Morita, K. Morimoto, D. Kaji, H. Haba, R. A. Boll, N. T. Brewer, S. Van Cleve, D. J. Dean, S. Ishizawa, Y. Ito, Y. Komori,K. Nishio, T. Niwase, B. C. Rasco, J. B. Roberto, K. P. Rykaczewski, H. Sakai, D. W. Stracener, and K. Hagino, “Fusion dynamics for
hot fusion reactions to synthesize superheavy nuclei revealed in quasielastic barrier distributions,” Phys. Rev. Lett. 124, 052502-1–96(2020).
M. U. Khandaker, H. Haba, Y. Komori, and N. Otuka, “Excitation functions of deuteron-induced nuclear reactions on erbium in the energy
range of 4–24 MeV,” Nucl. Instrum. Methods Phys. Res. B 470, 1–9 (2019).
Y. Wang, Y. Wittwer, J. Zhang, J. Yang, H. Haba, Y. Komori, T. Yokokita, S. Cao, F. Fan, R. Eichler, A. Türler, and Z. Qin, “Massspectrometric speciation of metal-carbonyls in the gas phase,” PSI Annual Report 2018, Laboratory of Radiochemistry, 13–14 (2019).
M. Sakaguchi, M. Aikawa, M. Saito, N. Ukon, Y. Komori, and H. Haba, “Production cross sections of 89 Zr by deuteron-induced reactions
on 89 Y,” JAEA-Conf 2019-001, 185–188 (2019).
T. Fukuchi, H. Haba, and H. Kikunaga, “Phantom production for a multiple-isotope β-ray imaging system,” ELPH Annual Report, Tohoku
University 2018, 105–106 (2019).
M. Saito, M. Aikawa, T. Murata, Y. Komori, H. Haba, S. Takács, F. Ditrói, and Z. Szűcs, “Production cross sections of 169 Yb by the
proton-induced reaction on 169 Tm,” Nucl. Instrum. Methods Phys. Res. B 471, 13–16 (2020).
Y. Kasamatsu, N. Kondo, K. Nakamura, Y. Kuboki, H. Ninomiya, Y. Shigekawa, E. Watanabe, Y. Yasuda, K. Toyomura, M. Nagase,
T. Yokokita, Y. Komori, H. Haba, T. Yoshimura, H. Itabashi, and A. Shinohara, “Solvent extraction of Zr and Hf from HCl by Aliquat
336 using a flow-type extraction apparatus toward online chemical studies of element 104, rutherfordium,” Solv. Extr. Ion Exch 38,
318–327 (2020).
Z. Tsoodol, M. Aikawa, I. Dagvadorj, T. Khishigjargal, N. Javkhlantugs, Y. Komori, and H. Haba, “Production cross sections of 68 Ga andradioactive by-products in deuteron-induced reactions on natural zinc,” Appl. Radiat. Isot. 159, 109095-1–8 (2020).
M. Sakaguchi, M. Aikawa, M. Saito, N. Ukon, Y. Komori, and H. Haba, “Activation cross section measurement of the deuteron-induced
reaction on yttrium-89 for zirconium-89 production”, Nucl. Instrum. Methods Phys. Res. B 472, 59–63 (2020).
T. Niwase, M. Wada, P. Schury, H. Haba, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Miyatake, K. Morimoto, K. Morita, M. Rosenbusch,
H. Wollnik, T. Shanley, and Y. Benari, “Development of an “α-TOF” detector for correlated measurement of atomic masses and decay
properties,” Nucl. Instrum. Methods Phys. Res. A 953, 163198-1–8 (2020).
J. Grund, M. Asai, K. Blaum, M. Block, S. Chenmarev, Ch. E. Düllmann, K. Eberhardt, S. Lohse, Y. Nagame, Sz. Nagy, P. Naubereit,
J. J. W. van de Laar, F. Schneider, T. K. Sato, N. Sato, D. Simonovski, K. Tsukada, and K. Wendt, “First online operation of TRIGATRAP,” Nucl. Instrum. Methods Phys. Res. A 972, 164013-1–8 (2020).
Y. Shigekawa, Y. Kasamatsu, Y. Yamakita, Y. Yasuda, E. Watanabe, N. Kondo, H. Haba, and A. Shinohara, “Development of a retardingfield type magnetic bottle spectrometer for studying the internal-conversion process of 235m U,” Nucl. Instrum. Methods Phys. Res. A
976, 164207-1–10 (2020).

[Review articles]
H. Haba, “The rewards and challenges of expanding the periodic table,” Chem. Eng. News, August 5, 36–37 (2019).
Ӌ৔޺ޫ, ʮୈ 8 प‫ظ‬ͷ৽‫ݩ‬ૉΛ‫ٻ‬Ίͯʯ, 40, 14–20 (2019).
Ӌ৔޺ޫ, ʮ೔ຊͷ‫ʹऀڀݚ‬ΑΔ৽‫ݩ‬ૉͷ୳ࡧͱप‫ظ‬දͷ։୓—χοϙχ΢Ϝ, 93 ൪‫ݩ‬ૉ, χϗχ΢Ϝ. ͞ΒͳΔ৽‫ݩ‬ૉΛ‫ٻ‬Ίͯ—ʯ,Խֶͱ޻‫ ۀ‬72, 944–945 (2019).
Ӌ৔޺ޫ, ʮཧ‫͚͓ʹݚ‬Δ֩ҩֶ࣏ྍ༻ϥδΦΞΠιτʔϓͷ੡଄ʯ, Drug Delivery Syst. 35, 114–120 (2020).
ւ໺߂ߦ, ּদྑਸ, ॏՏ༏େ, Ӌ৔޺ޫ, ฏ໦‫޺و‬, ૿ా޹඙, ࢁ‫ޱ‬ರ࢙, ԣ๺୎໵, ٢‫ݟ‬জ༸, ٢ଜߒ࢘, ʮߴً౓ X ઢΛ༻͍ͨ֩‫ڞ‬໐ࢄཚٕज़ʹΑΔ‫ ֩ࢠݪ‬229 Th ΞΠιϚʔঢ়ଶͷਓ޻ੜ੒ʯ, Isotope News No. 768, 2–6 (2020).

[Books]ࠤ౻๬, ޻౻‫ٱ‬ত, ʮ௒ॏ‫ݩ‬ૉͷ߹੒ʯ, in ʮϑϩϯςΟΞγϦʔζ 2 ௒ॏ‫ݩ‬ૉԽֶͷ࠷લઢʯ, Ӭ໨་Ұ࿠ʢฤஶʣ, pp. 6–13, ೔ຊ์- 346 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

ࣹԽֶձ, 2019 ೥ 9 ݄ 1 ೔.
๛ౢް࢙, Ӌ৔޺ޫ, ʮ௒ॏ‫ݩ‬ૉԽֶ—༹ӷԽֶʯ, in ʮϑϩϯςΟΞγϦʔζ 2 ௒ॏ‫ݩ‬ૉԽֶͷ࠷લઢʯ, Ӭ໨་Ұ࿠ʢฤஶʣ,pp. 41–48, ೔ຊ์ࣹԽֶձ, 2019 ೥ 9 ݄ 1 ೔.
ೆ෢ࢤ, ߴ‫ڮ‬࿨໵, ʮ‫ాژ‬Ҩ੻ 4 ۠ग़౔Ҩ෺෇ணਫۜगͷེԫಉҐମ෼ੳʯ, in ʮग़ӢࢢͷจԽࡒใࠂ 39 ‫ాژ‬Ҩ੻ 4 ۠ ൃ۷ௐࠪใ
ࠂॻʯ, ग़Ӣࢢ‫ڭ‬ҭҕһձ, pp. 165–168, 2019 ೥ 3 ݄.
Ӌ৔޺ޫʢ෼୲ࣥචʣ, ʮΞΠιτʔϓखா 12 ൛ʯ, ೔ຊΞΠιτʔϓ‫ڠ‬ձʢฤूɾൃߦʣ, ‫ؙ‬ળग़൛‫ࣜג‬ձࣾ, 2020 ೥ 3 ݄ 30 ೔.

[Proceedings]
H. Haba for RIKEN SHE Collaboration, “Present status and perspectives of SHE researches at RIKEN,” in “Proceedings of the international symposium on exotic nuclei, Petrozavodsk, Russia, 10–15 September 2018,” Yu. E. Penionzhkevich, Yu. G. Sobolev (Eds.),
World Scientific Publishing Co. Pte. Ltd., pp. 192–199 (2020).

Presentations[International conferences/workshops]
A. R. Usman, M. U. Khandaker, H. Haba, and N. Otuka (poster), “Cyclotron production cross sections of 61 Cu radionuclide fromnat
Ni(d, x)61 Cu nuclear reaction,” 2019 International Conference on Nuclear Data for Science and Technology (ND2019), Beijing,
China, May 19–24, 2019.
A. R. Usman, M. U. Khandaker, H. Haba, and N. Otuka (poster), “Towards formation of IAEA database for all metallic properties usefulin radionuclides production: eﬀect of varied titanium densities on excitation functions,” 2019 International Conference on Nuclear Data
for Science and Technology (ND2019), Beijing, China, May 19–24, 2019.
H. Haba (invited), “Production and applications of radioisotopes at RIKEN RI Beam Factory,” SHE Science Symposium, Oak Ridge,
USA, May 30, 2019.
H. Haba (invited), “Synthesis and chemistry of new elements at RIKEN,” 9th European Chemistry Congress, Berlin, Germany, June
17–18, 2019.
H. Kanda, T. Nakano, N. Aoi, M. H. Fukuda, T. Yorita, T. Suzuki, N. Takahashi, A. Shinohara, H. Haba, S. Kamigaito, H. Kikunaga,
H. Hama, T. Muto, H. Ikeda, H. Watabe, M. Itoh, H. Kawamura, Y. Sakemi, M. R. Zhang, K. Nagatsu, and H. Suzuki (oral), “Shortlived radioisotope supplying platform in Japan,” 39th Annual Conference of the Canadian Nuclear Society and 43rd Annual CNS/CNA
Student Conference, Ottawa, Canada, June 23–26, 2019.
T. Zolbadral, M. Aikawa, D. Ichinkhoroloo, K. Tegshjargal, N. Javkhlantugs, Y. Komori, and H. Haba (poster), “Production cross sectionsof 68 Ga and radioactive by-products in deuteron-induced reactions on natural zinc,” The 7th GI-CoRE Medical Science and Engineering
Symposium FLASH, MBA, & 4DRT, Hokkaido, Japan, August 18–19, 2019.
A. Yakushev, L. Lens, Ch. E. Düllmann, M. Asai, M. Block, H. Brand, H. M. David, J. Despotopulos, A. Di Nitto, K. Eberhardt, U. Forsberg, P. Golubev, M. Götz, S. Götz, H. Haba, L. Harkness-Brennan, W. Hartmann, R. -D. Herzberg, D. Hinde, J. Hoﬀmann, A. Hübner,
E. Jäger, M. Jourdan, D. Judson, J. Khuyagbaatar, B. Kindler, Y. Komori, J. Konki, J. V. Kratz, J. Krier, N. Kurz, M. Laatiaoui,
S. Lahiri, B. Lommel, M. Maiti, A. Mistry, Ch. Mokry, K. Moody, Y. Nagame, J. P. Omtvedt, P. Papadakis, V. Pershina, T. Reich,
D. Rudolph, J. Runke, L. Samiento, T. K. Sato, M. Schädel, P. Scharrer, B. Schausten, D. Shaughnessy, J. Steiner, P. Thörle-Pospiech,
A. Toyoshima, N. Trautmann, K. Tsukada, J. Uusitalo, K. -O. Voss, A. Ward, M. Wegrzecki, N. Wiehl, E. Williams, and V. Yakusheva(invited), “Chemical studies of superheavy elements at a recoil separator, with a focus on Fl,” 6th International Conference on theChemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
M. Götz, Ch. E. Düllmann, A. Yakushev, M. Asai, J. Ballof, A. Di Nitto, K. Eberhardt, S. Götz, H. Haba, E. Jäger, Y. Kaneya, Y. Komori,
J. V. Kratz, J. Krier, B. Lommel, A. Mitsukai, Y. Nagame, T. K. Sato, A. Toyoshima, K. Tsukada, V. Wolter, and V. Yakusheva (poster),“In-situ synthesis of volatile transition metal carbonyl complexes with short-lived radioisotopes,” 6th International Conference on theChemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
Z. Qin, Y. Wang, S. Cao, J. Zhang, J. Yang, H. Haba, F. Fan, Y. Komori, T. Yokokita, K. Morimoto, D. Kaji, Y. Wittwer, R. Eichler,
and A. Türler (poster), “The study of rhenium pentacarbonyl complexes using single-atom chemistry in gas phase,” 6th International
Conference on the Chemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
Y. Wang, Y. Wittwer, J. Zhang, J. Yang, H. Haba, Y. Komori, T. Yokokita, S. Cao, F. Fan, R. Eichler, A. Türler, and Z. Qin (oral), “Thespecies identification of Mo, W, and Re carbonyl complexes with laserablation time-of-flight mass-spectrometry,” 6th International
Conference on the Chemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
L. Lens, A. Yakushev, Ch. E. Düllmann, M. Asai, M. Block, H. Brand, M. Dasgupta, H. M. David, J. Despotopulos, A. Di Nitto,
K. Eberhardt, M. Götz, P. Golubev, S. Götz, H. Haba, L. Harkness-Brennan, F. P. Heßberger, R. -D. Herzberg, D. Hinde, J. Hoﬀmann,
A. Hübner, E. Jäger, D. Judson, J. Khuyagbaatar, B. Kindler, Y. Komori, J. Konki, J. V. Kratz, J. Krier, N. Kurz, M. Laatiaoui,
S. Lahiri, B. Lommel, M. Maiti, A. K. Mistry, C. Mokry, K. Moody, Y. Nagame, J. P. Omtvedt, P. Papadakis, V. Pershina, A. Roth,
D. Rudolph, J. Runke, L. Sarmiento, M. Schädel, P. Scharrer, T. Sato, D. Shaughnessy, B. Schausten, J. Steiner, P. Thörle-Pospiech,
N. Trautmann, K. Tsukada, J. Uusitalo, A. Ward, M. Wegrzecki, E. Williams, N. Wiehl, V. Yakusheva (poster), “Optimizations of the
TASCA-COMPACT setup towards chemical studies of nihonium (element 113),” 6th International Conference on the Chemistry andPhysics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
T. Niwase, M. Wada, P. Schury, Y. Ito, S. Kimura, D. Kaji, M. Rosenbusch, Y. Watanabe, Y. Hirayama, H. Miyatake, J. Y. Moon,
H. Ishiyama, K. Morimoto, H. Haba, T. Tanaka, S. Ishizawa, A. Takamine, K. Morita, and H. Wollnik (poster), “Development and first
results from a novel “α-ToF” detector used with a multi-reflection time-of-flight mass spectrograph,” 6th International Conference on
the Chemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
T. Tanaka, K. Morita, K. Morimoto, D. Kaji, H. Haba, R. A. Boll, N. T. Brewer, S. V. Cleve, D. J. Dean, S. Ishizawa, Y. Ito, Y. Komori,- 347 -

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K. Nishio, T. Niwase, B. C. Rasco, J. B. Roberto, K. Rykaczewski, H. Sakai, D. W. Stracener, and K. Hagino (oral), “Fusion dynamics
for hot fusion reactions revealed in quasielastic barrier distributions,” 6th International Conference on the Chemistry and Physics of theTransactinide Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
M. Wada, P. Schury, H. Miyatake, Y. X. Watanabe, Y. Hirayama, H. Wollnik, S. Kimura, S. Ishizawa, T. Niwase, M. Rosenbusch, D. Kaji,
K. Morimoto, H. Haba, I. Takamine, T. Tanaka, H. Ishiyama, Y. Ito, J. Y. Moon, and K. Morita (invited), “SHE-Mass-II setup for direct
mass measurement of hot-fusion superheavy nuclides,” 6th International Conference on the Chemistry and Physics of the Transactinide
Elements (TAN19), Wilhelmshaven, Germany, August 25–30, 2019.
Y. Ito, P. Schury, M. Wada, F. Arai, H. Haba, Y. Hirayama, S. Ishizawa, D. Kaji, S. Kimura, H. Koura, M. Maccormick, H. Miyatake,J. -Y. Moon, K. Morimoto, K. Morita, M. Mukai, I. Murray, T. Niwase, K. Okada, A. Ozawa, M. Rosenbusch, A. Takamine, T. Tanaka,
Y. Watanabe, H. Wollnik, and S. Yamaki (oral), “Direct mass measurements of mendelevium isotopes in the vicinity of the N =152 deformed shell-closure,” 6th International Conference on the Chemistry and Physics of the Transactinide Elements (TAN19),
Wilhelmshaven, Germany, August 25–30, 2019.
M. Okamura (oral), E. Beebe, S. Ikeda, T. Kanesue, D. Raparia, and H. Haba, “96 Zr beam production for isobar experiment in RHIC,”
The 18th International Conference on Ion Sources (ICIS’19), Lanzhou, China, September 1–6, 2019.
H. Haba (invited), “Present status and perspectives of superheavy element researches at RIKEN,” XXXVI’th Mazurian Lakes Conference
on Physics, Piaski, Poland, September 1–7, 2019.
H. Haba (invited), “RI production—Chemistry of new elements to diagnosis and treatment of cancer—,” Tsukuba Conference 2019,
Tsukuba, Japan, October 2–4, 2019.
T. Fukuchi, M. Shigeta, H. Haba, S. Yamamoto, and Y. Watanabe (poster), “Imaging performance evaluation of a multiple-isotope PET
with 44m Sc tracer,” 2019 IEEE Nuclear Science Symposium (NSS) and Medical Imaging Conference (MIC), Manchester, UK, October
26–November 2, 2019.
T. Zolbadral, M. Aikawa, D. Ichinkhoroloo, T. Khishigjargal, Y. Komori, H. Haba, S. Takács, F. Ditrói, and Z. Szűcs (poster), “Production
cross sections of 45 Ti via deuteron-induced reaction on scandium,” 2019 Symposium on Nuclear Data, Fukuoka, Japan, November
28–30, 2019.
M. Saito, M. Aikawa, T. Murata, Y. Komori, H. Haba, S. Takács, F. Ditrói, and Z. Szűcs (poster), “Production of 169 Yb by the protoninduced reaction on 169 Tm,” 2019 Symposium on Nuclear Data, Fukuoka, Japan, November 28–30, 2019.
Y. Kasamatsu, H. Ninomiya, S. Hayami, M. Nagase, E. Watanabe, Y. Shigekawa, N. Kondo, H. Haba, T. Yokokita, Y. Komori, D. Mori,Y. Wang, K. Ghosh, M. Kaneko, and A. Shinohara (poster), “Coprecipitation of nobelium with samarium hydroxide,” The 4th International Symposium on Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
E. Watanabe, S. Hayami, K. Tonai, H. Ninomiya, K. Ouchi, Y. Kasamatsu, Y. Kitagawa, M. Nakano, Y. Shigekawa, T. Yokokita, and
A. Shinohara (poster), “Anion-exchange Experiment of Zr, Hf, and Th in HNO3 ,” The 4th International Symposium on Superheavy
Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
Z. Qin, Y. Wang, S. W. Cao, J. C. Zhang, F. L. Fang, J. Yang, H. Haba, Y. Komori, T. Yokokita, K. Morimoto, D. Kaji, Y. Wittwer,
R. Eichler, and A. Türler (invited), “Towards the bohrium carbonyl complexes in gas phase,” The 4th International Symposium on
Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
Y. Wang, Y. Wittwer, J. Zhang, S. Cao, Y. Komori, T. Yokokita, Y. Shigekawa, F. Fan, J. Yang, H. Haba, R. Eichler, A. Türler, and Z. Qin(oral), “Species identification of Re carbonyls using laser-ablation time-of-flight mass-spectrometer,” The 4th International Symposiumon Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
T. Yokokita, Y. Kasamatsu, E. Watanabe, Y. Komori, H. Ninomiya, Y. Wang, D. Mori, K. Ghosh, A. Shinohara, and H. Haba (oral),“Anion exchange of Rf, Zr, Hf, and Th in H2 SO4 ,” The 4th International Symposium on Superheavy Elements (SHE2019), Hakone,
Japan, December 1–5, 2019.
T. Niwase, M. Wada, P. Schury, Y. Ito, S. Kimura, D. Kaji, M. Rosenbusch, Y. X. Watanabe, Y. Hirayama, H. Miyatake, J. Y. Moon,
H. Ishiyama, K. Morimoto, H. Haba, T. Tanaka, S. Ishizawa, A. Takamine, K. Morita, and H. Wollnik (oral), “Correlation measurement of precision mass and decay properties of nuclei via MRTOF-MS with α-ToF detector,” The 4th International Symposium on
Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
M. Rosenbusch, M. Wada, P. Schury, S. Iimura, H. Haba, Y. Hirayama, H. Ishiyama, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Miyatake, J. Y. Moon, K. Morimoto, T. Tanaka, T. Niwase, A. Takamine, K. Morita, Y. X. Watanabe, and H. Wollnik (oral), “Dynamic
ejection-field correction for MR ToF mass spectrometry of SHE using arbitrary mass references,” The 4th International Symposium on
Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
H. Haba (plenary), “Production and applications of radioisotopes at RIKEN RI Beam Factory—Search for new elements through diagnosis
and therapy of cancer—,” The 10th International Conference on Isotopes (10ICI), Kuala Lumpur, Malaysia, February 3–7, 2020.
H. Haba (invited), “Present status and perspectives of superheavy element chemistry at RIKEN,” The 10th International Conference on
Isotopes (10ICI), Kuala Lumpur, Malaysia, February 3–7, 2020.
Y. Komori, M. Murakami, and H. Haba (oral), “Measurements of excitation functions for the nat W(d, x) reactions based on new half-livesof rhenium isotopes,” The 10th International Conference on Isotopes (10ICI), Kuala Lumpur, Malaysia, February 3–7, 2020.

[Seminars]
H. Haba, “Production of radioisotopes for application Studies at RIKEN RI Beam Factory,” Seminar at Institute of Modern Physics (IMP),
Lanzhou, China, August 12, 2019.
H. Haba, “Production of radioisotopes for application Studies at RIKEN RI Beam Factory,” IFIN-HH Seminar at Horia Hulubei National
Institute for R&D in Physics and Nuclear Engineering, Bucharest, Rumania, October 21, 2019.
Y. Komori, “Aqueous chemistry of superheavy elements at RIKEN,” IFIN-HH Seminar at Horia Hulubei National Institute for R&D in- 348 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Physics and Nuclear Engineering, Bucharest, Rumania, October 21, 2019.
H. Haba, “Production of radioisotopes for application studies at RIKEN RI Beam Factory”, Seminar at Sunway University, Selangor,
Malaysia, February 10, 2020.
Y. Komori, “Excitation function measurements in RIKEN”, Seminar at Sunway University, Selangor, Malaysia, February 10, 2020.

[Domestic conferences/workshops]
෱஍஌ଇ, ॏాඒ߳, Ӌ৔޺ޫ, ࢁຊ੣Ұ, ౉ล‫ྑګ‬, ӿຊलҰʢ‫ޱ‬಄ൃදʣ, ʮཅిࢠ–ΨϯϚઢ์ग़֩ 44 Sc Λ༻͍ͨෳ਺τϨʔαʔPET Πϝʔδϯάʯ, ೔ຊ෼ࢠΠϝʔδϯάֶձୈ 14 ճ૯ձɾֶज़ूձ, ࡳຈ, 2019 ೥ 5 ݄ 23–24 ೔.
౻Ҫത࢙, େ؏࿨৴, ∁ౡେً, ‫ݹ‬լએউ, ௡ଜྒྷ, দଜอ޿, Ӌ৔޺ޫ, Wang Yang, Kaustab Ghosh, খ৿༗‫ࢠر‬, ԣ๺୎໵, ৿େً,ᚸು࢙೫ʢϙελʔൃදʣ, ʮҩྍࢪઃͰͷ α ઢ์ग़֩छ 211 At ͷଌఆ‫ܥ‬ͷߏஙʯ, ೔ຊ෼ࢠΠϝʔδϯάֶձୈ 14 ճ૯ձɾֶज़
ूձ, ࡳຈ, 2019 ೥ 5 ݄ 23–24 ೔.
ຊଜ৴࣏, ‫ت‬Ҫ‫܄‬, Ӌ৔޺ޫ, ༀࢣࣉलथ, ౉ล‫ྑګ‬, ӿຊलҰʢ‫ޱ‬಄ൃදʣ, ʮ൒ಋମίϯϓτϯΧϝϥ GREI ʹΑΔ Na+ /K+ ͷಉ࣌Πϝʔδϯάʯ, ೔ຊ෼ࢠΠϝʔδϯάֶձୈ 14 ճ૯ձɾֶज़ूձ, ࡳຈ, 2019 ೥ 5 ݄ 23–24 ೔.
৿େً, ԣ๺୎໵, খ৿༗‫ࢠر‬, Ԧ༸, Ӌ৔޺ޫ, ਆాߊॆ, ࿬୩༤Ұ࿠, দຊ‫װ‬༤, ໦ଜढ़෉ʢ‫ޱ‬಄ൃදʣ,ʮཧ‫͚͓ʹݚ‬Δ൦෍༻ਫ਼੡
42, 43K ͓Αͼ 44m Sc ͷ੡଄ٕज़։ൃʯ, ୈ 56 ճΞΠιτʔϓɾ์ࣹઢ‫ൃڀݚ‬දձ, จ‫ژ‬, 2019 ೥ 7 ݄ 3–5 ೔.
ॏՏ༏େʢ‫ޱ‬಄ൃදʣ, ʮ235m U ͱ 229m Th ͷ಺෦స‫׵‬աఔʹର͢ΔԽֶޮՌʯ, ୈ 58 ճ֩ԽֶՆͷֶߍ, ༝෍, 2019 ೥ 9 ݄ 11–14 ೔.
খ৿༗‫ࢠر‬ʢ‫ޱ‬಄ൃදʣ, ʮཧ‫ݚ‬ͷ֩Խֶ‫ڥ؀ڀݚ‬ʯ, ୈ 58 ճ֩ԽֶՆͷֶߍ, ༝෍, 2019 ೥ 9 ݄ 11–14 ೔.
ᜊ౻๖ඒ, ߹઒ਖ਼޾, ࡔ‫ޱ‬ཧ࠸, ӈۙ௚೭, খ৿༗‫ࢠر‬, Ӌ৔޺ޫ, λΧοναϯυʔϧʢ‫ޱ‬಄ൃදʣ, ʮՙిཻࢠೖࣹ൓Ԡʹ͓͚Δҩ
ྍ༻์ࣹੑ֩छ 169 Yb ੜ੒அ໘ੵଌఆ࣮‫ݧ‬ʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥ळͷେձ, ෋ࢁ, 2019 ೥ 9 ݄ 11–13 ೔.
ଜా๎େ, ߹઒ਖ਼޾, ࡔ‫ޱ‬ཧ࠸, Ӌ৔޺ޫ, খ৿༗‫ࢠر‬, λΧναϯυʔϧ, ϑΣϨϯνσΟτϩΠ, ζʔνκϧλϯʢ‫ޱ‬಄ൃදʣ, ʮDyඪత΁ͷΞϧϑΝཻࢠরࣹʹΑΔ 166 Ho ͷྭ‫਺ؔى‬ଌఆʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥ळͷେձ, ෋ࢁ, 2019 ೥ 9 ݄ 11–13 ೔.
ࡔ‫ޱ‬ཧ࠸, ߹઒ਖ਼޾, ᜊ౻๖ඒ, ӈۙ௚೭, খ৿༗‫ࢠر‬, Ӌ৔޺ޫʢ‫ޱ‬಄ൃදʣ, ʮ89 Zr ੜ੒Λ໨తͱͨ͠ 89 Y ഩ΁ͷॏཅࢠরࣹʹ͓
͚Δੜ੒அ໘ੵͷଌఆʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥ळͷେձ, ෋ࢁ, 2019 ೥ 9 ݄ 11–13 ೔.
I. Dagvadorj, M. Aikawa, T. Zolbadral, Y. Komori, H. Habaʢ‫ޱ‬಄ൃදʣ, ʮProduction cross sections of dysprosium radioisotopes indeuteron-induced reactions on natural terbium up to 24 MeVʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥ळͷେձ, ෋ࢁ, 2019 ೥ 9 ݄ 11–13 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮ৽‫ݩ‬ૉԽֶͷల๬ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑ଠ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. Moon, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ߴๆѪࢠ, ৿ాߒհ, H. Wollnikʢ‫ޱ‬಄ൃදʣ, ʮMRTOF-MS Λ༻͍ͨ 207 Ra ͷਫ਼ີ࣭ྔ—่յಛੑଌఆʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
૿ా޹඙, Kjeld Beeks, Ӌ৔޺ޫ, ‫ݪ‬ल໌, ฏ໦‫޺و‬, ౻ࢬ྄, ౻ຊ߂೭, ླ໦݈ଠ, ւ໺߂ߦ, ּদྑਸ, ๺ඌਅ࢘, খແ݈࢘, ‫ٶ‬ຊ༞थ,ԬҪߊҰ, ࡫ඌొ, ࠤ౻ଳࢠ, Thorsten Schumm, ੉‫ށ‬੣, ॏՏ༏େ, Simon Stellmer, ‫࣏ݡ࡞ۄ‬, ২஛ஐ, ౉෦৴, ౉෦࢘, ࢁ‫ޱ‬ರ࢙,҆ా༐ً, ґా๕୎, ٢‫ݟ‬জ༸, ٢ଜߒ࢘, ٢ଜଠ඙ʢ‫ޱ‬಄ൃදʣ, ʮτϦ΢Ϝ 229 ‫֩ࢠݪ‬ҟੑମ͔Βͷਅۭࢵ֎ޫ‫؍‬ଌͷ‫ݱ‬ঢ়ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17–20 ೔.
౉ᬒӯհ, ଎ਫᠳ, ౦಺ࠀഅ, ּদྑਸ, ๺Տ߁ོ, ॏՏ༏େ, ԣ๺୎໵, த໺խ༝, ࣰ‫ްݪ‬ʢϙελʔൃදʣ, ʮ঳ࢎதʹ͓͚Δ Zr, Hf͓Αͼ Th ͷࡨ‫ܗ‬੒ʹؔ͢Δ࣮‫ݧ‬ɾཧ࿦‫—ڀݚ‬௒ॏ‫ݩ‬ૉ Rf ͷԽֶ‫—͚ͯ޲ʹڀݚ‬ʯ, ୈ 13 ճ෼ࢠՊֶ౼࿦ձ 2019 ໊‫ݹ‬԰, ໊‫ݹ‬԰, 2019 ೥ 9 ݄ 17–20 ೔.
ૣ઒༏ଠ, ࡔ‫ޱ‬ҁ, ଜాਅ༏, দଜՆ‫ل‬, ౻পमฏ, தౡ࿕‫ٱ‬, ּদྑਸ, ࣰ‫ްݪ‬, খ৿༗‫ࢠر‬, ԣ๺୎໵, ৿େً, ໼ೲ৻໵, Ӌ৔޺ޫ,ԣࢁ໌඙ʢ‫ޱ‬಄ൃදʣ, ʮU+p ‫ ͼٴ‬Th+Li ൓ԠʹΑΔ Np ಉҐମྭ‫਺ؔى‬ͷ࡞੒ʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ
͖, 2019 ೥ 9 ݄ 24–26 ೔.
খ৿༗‫ࢠر‬, ଜ্ণ࢙, Ӌ৔޺ޫʢ‫ޱ‬಄ൃදʣ, ʮnat W(d, x) ൓ԠʹΑΔ Re ಉҐମͷྭ‫ͱ਺ؔى‬൒‫ظݮ‬ͷଌఆʯ, ೔ຊ์ࣹԽֶձୈ 63ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
Y. Wang, N. Sato, Y. Komori, T. Yokokita, D. Mori, S. Usuda, H. Habaʢ‫ޱ‬಄ൃදʣ, ʮProduction of At-211 at RIKENʯ, ೔ຊ์ࣹԽֶ
ձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
ԣ๺୎໵, ּদྑਸ, ౉ᬒӯհ, খ৿༗‫ࢠر‬, ೋ‫ٶ‬लඒ, Ԧ༸, ৿େً, ΰʔγϡίʔελϒ, ࣰ‫ް ݪ‬, Ӌ৔޺ޫʢ‫ޱ‬಄ൃදʣ, ʮེࢎ‫ܥ‬ʹ͓͚Δ Rf ͷӄΠΦϯަ‫׵‬ʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
౉ᬒӯհ, ଎ਫᠳ, ౦಺ࠀഅ, ೋ‫ٶ‬लඒ, ּদྑਸ, ๺Տ߁ོ, ॏՏ༏େ, ԣ๺୎໵, த໺խ༝, ࣰ‫ްݪ‬ʢ‫ޱ‬಄ൃදʣ, ʮZr, Hf, Th ͷ঳ࢎࡨମ‫ܗ‬੒ʹؔ͢Δ࣮‫͓ݧ‬Αͼཧ࿦‫ ڀݚ‬Rf ͷԽֶʹ޲͚ͯ ʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
଎ਫᠳ, ೋ‫ٶ‬लඒ, ౉ᬒӯհ, ॏՏ༏େ, Ӭ੉কߒ, ּদྑਸ, ۙ౻੒ඒ, Ӌ৔޺ޫ, ԣ๺୎໵, খ৿༗‫ࢠر‬, ৿େً, Ԧ༸, ΰʔγϡίʔελϒ, ࠤ౻๬, ࣰ‫ްݪ‬ʢ‫ޱ‬಄ൃදʣ, ʮਫࢎԽαϚϦ΢Ϝ‫ڞ‬௜๏Λ༻͍ͨ 102 ൪‫ݩ‬ૉϊʔϕϦ΢Ϝͷ௜఼࣮‫ݧ‬ʯ, ೔ຊ์ࣹԽֶձ
ୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
ॏՏ༏େ, ּদྑਸ, ࢁ๺Ղ޺, ۚࢠ੓ࢤ, ౉ᬒխ೭, ౉ᬒӯհ, ҆ా༐ً, ۙ౻੒ඒ, ࣰ‫ްݪ‬ʢ‫ޱ‬಄ൃදʣ, ʮࢎԽ෺ɾϑοԽ෺ɾԘԽ
෺‫͚͓ʹܥ‬Δ U-235m ͷ൒‫͓ظݮ‬Αͼ಺෦స‫ࢠి׵‬ΤωϧΪʔεϖΫτϧͷଌఆʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
ॏՏ༏େ, ּদྑਸ, ౉ᬒӯհ, ҆ా༐ً, ۙ౻੒ඒ, ೋ‫ٶ‬लඒ, ଎ਫᠳ, Ӌ৔޺ޫ, ࣰ‫ްݪ‬ʢ‫ޱ‬಄ൃදʣ, ʮAc-229 ͷ β ઢ—ిࢠಉ࣌‫਺ܭ‬ଌఆʹΑΔ Th-229m ͷ಺෦స‫ࢠి׵‬ͷ‫؍‬ଌʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. Moon, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ߴๆѪࢠ, ৿ాߒհ, H. Wollnikʢ‫ޱ‬಄ൃදʣ, ʮMRTOF + α-TOF Λ༻͍ͨ 207 Ra ͷ࣭ྔ–่յಛੑଌఆʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
Ӎ૔‫ܒ‬, ळࢁ࿨඙, Ӌ৔޺ޫ, ‫ٱ‬෌໦ࢤ࿠ʢ‫ޱ‬಄ൃදʣ, ʮϥϯλϊΠυ಺แϑϥʔϨϯʢLn3+ @C82 3− ʣʹ͓͚Δ಺แۚଐ‫୸͕ࢠݪ‬ૉέʔδʹ‫ઁ͢΅ٴ‬ಈతӨ‫ڹ‬ʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
੨Ҫ‫౎ܠ‬, ৽༟‫و‬, ઒㟒߁ฏ, ౦ඒཬ, ࿯ࢁ޾৴, ੢தҰ࿕, Ӌ৔޺ޫ, ৿େً, Yang Wang, ԣࢁ໌඙ʢϙελʔൃදʣ, ʮRn-211/At-211- 349 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

δΣωϨʔλγεςϜʹඞཁͳ 207 Po আ‫ڈ‬๏ͷ‫ݕ‬౼ʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
҆ୡασΟΞ, ຤໦‫ܒ‬հ, ๛ౢް࢙, ௩ా࿨໌, Ӌ৔޺ޫ, খ৿༗‫ࢠر‬, ԣ๺୎໵, ৿େًʢϙελʔൃදʣ, ʮHF/HNO3 ਫ༹ӷதʹ
͓͚Δ Nb, Ta, Pa ͷӄΠΦϯަ‫ݧ࣮׵‬ʙDb ϑοԽ෺ࡨମͷਪఆʹ޲͚ͯʙʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖,2019 ೥ 9 ݄ 24–26 ೔.
৿ాྋխ, ૣ઒༏ଠ, খ৿༗‫ࢠر‬, ԣ๺୎໵, ৿େً, Ӌ৔޺ޫ, ּদྑਸ, ࣰ‫ްݪ‬, ԣࢁ໌඙ʢϙελʔൃදʣ, ʮ239 Np ෳ߹֩‫͓ʹܥ‬͚Δ֩෼྾அ໘ੵଌఆʹΑΔ‫ي‬ಓ֯ӡಈྔͷਪఆʯ, ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձʢ2019ʣ, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
ԣ๺୎໵ʢ‫ޱ‬಄ൃදʣ, ʮ৽‫ن‬ΨϯϚઢΠϝʔδϯά༻ϓϩʔϒ K-42, K-43 ‫ ͼٴ‬Sc-44m ͷ੡଄ʯ, ୈೋճ Chemical Probe ߹ಉ߹॓ηϛφʔ, ཛྷࢁொ, 2019 ೥ 10 ݄ 8–9 ೔.
খ৿༗‫ࢠر‬ʢϙελʔൃදʣ, ʮ༗༻ RI ϓϩʔϒ੡଄ʹ޲͚ͨ֩൓Ԡྭ‫਺ؔى‬ͷଌఆʯ, ୈೋճ Chemical Probe ߹ಉ߹॓ηϛφʔ,ཛྷࢁொ, 2019 ೥ 10 ݄ 8–9 ೔.
Y. Wangʢϙελʔൃදʣ, ʮProduction of a therapeutic isotope, astatine-211 at RIBFʯ, ୈೋճ Chemical Probe ߹ಉ߹॓ηϛφʔ, ཛྷࢁொ, 2019 ೥ 10 ݄ 8–9 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮ৽‫ݩ‬ૉΛ୳ͦ͏! ʯ, ೔ຊԽֶձ ‫ͪͨ܅‬ͷকདྷͱԽֶͷະདྷ ౦େͰա͢͝Խֶͳि຤, จ‫ژ‬, 2019 ೥ 10 ݄
20 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮ113 ൪χϗχ΢Ϝͷൃ‫ݟ‬ʯ, ࠃࡍप‫ظ‬ද೥ 2019 ಛผలΦʔϓχϯάΠϕϯτ, ࢁ‫ܗ‬, 2019 ೥ 11 ݄ 3 ೔.
ՖԬ޺࢙, େౡ߁޺, ླ໦ത‫ݩ‬, ࠤʑ໦Ұ࿠, ౉ลໜथ, Ӌ৔޺ޫ, ߥ໺ହ, ੴԬయࢠ, ରഅٛਓʢ‫ޱ‬಄ൃදʣ, ʮAt-211 ඪࣝ α ϝνϧ–ϑΣχϧΞϥχϯΛ༻͍ͨ಺༻์ࣹઢྍ๏ʯ, ೔ຊ֩ҩֶձୈ 61 ճֶज़૯ձ, দࢁ, 2019 ೥ 11 ݄ 4–6 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮ‫ݩ‬ૉΛͭ͘Ζ͏! ʯ, αΠΤϯεΞΰϥࠃࡍप‫ظ‬ද೥ಛผ‫ا‬ը‫ݩ‬ૉ‫ݕ‬ఆ 2019@౦‫ژ‬, ߐ౦, 2019 ೥ 11 ݄
16 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮϥδΦΞΠιτʔϓͷ੡଄ͱԠ༻—৽‫ݩ‬ૉͷ୳ࡧ͔Β͕Μͷ਍அɾ࣏ྍ·Ͱ—ʯ, 2019 ೥౓೔ຊΞΠιτʔϓ‫ڠ‬ձγϯϙδ΢ϜʮPETɾΠϝʔδϯά‫ڀݚ‬ͷ࠷લઢʙϥΠϑαΠΤϯεͱཧ޻ֶͷ༥߹ʙʯ, ઒࡚, 2019 ೥ 11 ݄ 22 ೔.
ߴ‫ڮ‬࿨໵ʢ‫ج‬ௐߨԋʣ, ʮ‫ۃ‬ඍྔͷེԫಉҐମൺ෼ੳʹΑΔ, Ҩ੻͔Βग़౔ͨ͠ਫۜगͷ࢈஍ಉఆʯ, ೔ຊ෼ੳԽֶձ ୈ 370 ճΨεΫϩϚτάϥϑΟʔ‫ڀݚ‬ձಛผߨԋձ, ๺, 2019 ೥ 11 ݄ 22 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ, ʮଟޫࢠΨϯϚઢ์ग़֩छͷ੡଄ʯ, ʮଟޫࢠΨϯϚઢ࣌ؒ/ۭؒ૬ؔ‫ܕ‬அ૚ࡱ૾๏ͷ‫ڀݚ‬ʯϫʔΫγϣοϓ,ߓ, 2019 ೥ 12 ݄ 6 ೔.
∁ౡେً, ‫ݹ‬լએউ, େ؏࿨৴, ᚸು࢙೫, ௡ଜྒྷ, ҆੢ߴኍ, ‫ాؠ‬๬, Wang Yang, ԣ๺୎໵, খ৿༗‫ࢠر‬, ৿େً, Ӌ৔޺ޫ, ౻Ҫത࢙,দଜอ޿ʢϙελʔൃදʣ, ʮΞϧϑΝઢ์ग़֩छΞελνϯ-211 Λ༻͍ͨ์ࣹ໔Ӹྍ๏ͷ։ൃʯ, ୈ 5 ճ AMED ͕Μएख‫ڀݚ‬ऀϫʔΫγϣοϓ, ઍ୅ా, 2020 ೥ 1 ݄ 9 ೔.
Ӌ৔޺ޫʢট଴ߨԋʣ,ʮཧ‫͚͓ʹݚ‬ΔϥδΦΞΠιτʔϓͷ੡଄ͱԠ༻ʙ৽‫ݩ‬ૉͷ୳ࡧ͔Β͕Μͷ਍அɾ࣏ྍ·Ͱʙʯ, ୈ 75 ճ์ࣹઢ‫ܭ‬ଌ‫ڀݚ‬ձ, ࿨ޫ, 2020 ೥ 1 ݄ 18 ೔.
ߴ‫ߒڮ‬೭, ౡఴ݈࣍, ‫ܓాח‬, Ӌ৔޺ޫ, ඦ੉හޫʢ‫ޱ‬಄ൃදʣ,ʮଟޫࢠΨϯϚઢ࣌ؒɾۭؒ૬ؔ‫ܕ‬Πϝʔδϯά๏ͷ‫ ڀݚ‬1ʢ֓ཁʣʯ,2020 ೥ୈ 67 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, ઍ୅ా, 2020 ೥ 3 ݄ 12–15 ೔.
‫ܓాח‬, ۚ‫ܟ‬᭪, ٢໺কੜ, ঙࢠҭ޺, ࢁ࿏ߊ߂, ࠇᖒढ़հ, ԣా༗ҝ, େ‫ڮ‬༤ೋ, ౡఴ݈࣍, ߴ‫ڮ‬ඒ࿨ࢠ, Ӌ৔޺ޫ, ඦ੉හޫ, ߴ‫ߒڮ‬೭, ٢઒জʢ‫ޱ‬಄ൃදʣ, ʮଟޫࢠΨϯϚઢ࣌ؒɾۭؒ૬ؔ‫ܕ‬Πϝʔδϯά๏ͷ‫ ڀݚ‬2ʢγϯνϨʔλ։ൃʣʯ, 2020 ೥ୈ 67 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, ઍ୅ా, 2020 ೥ 3 ݄ 12–15 ೔.
Ӌ৔޺ޫ, ৿େً, খ৿༗‫ࢠر‬, ԣ๺୎໵, Ԧ༸, ߴ‫ߒڮ‬೭, ౡఴ݈࣍, ‫ܓాח‬, ඦ੉හޫ, ߴ‫ڮ‬ඒ࿨ࢠʢ‫ޱ‬಄ൃදʣ, ʮଟޫࢠΨϯϚઢ࣌ؒɾۭؒ૬ؔ‫ܕ‬Πϝʔδϯά๏ͷ‫ ڀݚ‬3ʢRI ੡଄ʣʯ, 2020 ೥ୈ 67 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, ઍ୅ా, 2020 ೥ 3 ݄
12–15 ೔.
େ৊݈Ұ࿕, ҪԼහ޹, Ԭ࡚‫ل‬༤, ‫ܡࢁݹ‬ଠ࿠, ߴ‫ڮ‬ඒ࿨ࢠ, ඦ੉හޫ, ߴ‫ߒڮ‬೭, ౡఴ݈࣍, ‫ܓాח‬, Ӌ৔޺ޫʢ‫ޱ‬಄ൃදʣ, ʮଟޫࢠΨϯϚઢ࣌ؒɾۭؒ૬ؔ‫ܕ‬Πϝʔδϯά๏ͷ‫ ڀݚ‬4ʢҩྍԠ༻ʣʯ, 2020 ೥ୈ 67 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, ઍ୅ా, 2020
೥ 3 ݄ 12–15 ೔.
্ϊொਫ‫ل‬, Zhong Zhihong, େ৊݈Ұ࿠, ౡఴ݈࣍, ߴ‫ߒڮ‬೭, ‫ܓాח‬, Ӌ৔޺ޫ, ߴ‫ڮ‬ඒ࿨ࢠ, ඦ੉හޫʢ‫ޱ‬಄ൃදʣ, ʮଟޫࢠΨϯϚઢ࣌ؒɾۭؒ૬ؔ‫ܕ‬Πϝʔδϯά๏ͷ‫ ڀݚ‬5ʢγεςϜ։ൃʣʯ, 2020 ೥ୈ 67 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, ઍ୅ా, 2020
೥ 3 ݄ 12–15 ೔.
খᖒ௚໵, ௕ᖛ߂‫ق‬, ૣਫ༑༸, தଜ‫ܓ‬༎, খߴ߁র, ాத߳௡ੜ, େ௩ະདྷ, খ৿༗‫ࢠر‬, ࢢ઒༤Ұ, Ӌ৔޺ޫ, ্໺लथ, ञ‫ݟ‬ହ‫׮‬ʢ‫ޱ‬಄ൃදʣ,ʮϑϥϯγ΢Ϝ‫ࢠݪ‬ͷి‫ؾ‬૒‫ࢠۃ‬ೳ཰୳ࡧͷͨΊͷද໘ి཭ΠΦϯ‫ݯ‬ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձʢ2020೥ʣ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
ࡔ౦༎੕, ੨໦ঊ, ᓎҪതّ, ৽૔५, ླ໦େհ, Ӌ৔޺ޫʢ‫ޱ‬಄ൃදʣ,ʮ์ࣹԽ๏ʹΑΔଟதੑࢠ‫֩ࢠݪ‬ͷ୳ࡧʯ, ೔ຊ෺ཧֶձୈ
75 ճ೥࣍େձʢ2020 ೥ʣ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
ւ໺߂ߦ, Ӌ৔޺ޫ, ‫ݪ‬ल໌, ฏ໦‫޺و‬, ౻ࢬ྄, ౻ຊ߂೭, ּদྑਸ, ๺ඌਅ࢘, খແ݈࢘, ૿ా޹඙, ‫ٶ‬ຊ༞थ, ԬҪߊҰ, ࡫ඌొ,Kjeld Beeks, Thorsten Schumm, ੉‫ށ‬੣, ॏՏ༏େ, A. Simon Stellmer, ‫࣏ݡ࡞ۄ‬, ২஛ஐ, ౉෦৴, ౉෦࢘, ࢁ‫ޱ‬ರ࢙, ҆ా༐ً, ґా๕୎, ٢‫ݟ‬জ༸, ٢ଜߒ࢘, ٢ଜଠ඙ʢ‫ޱ‬಄ൃදʣ, ʮτϦ΢Ϝ 229 ΞΠιϚʔ४Ґ͔Βͷਅۭࢵ֎ޫͷ୳ࡧʯ, ೔ຊ෺ཧֶձୈ 75ճ೥࣍େձʢ2020 ೥ʣ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, Ճ࣏େ࠸, M. Rosenbusch, ౉ล༟, ฏࢁլҰ, ‫ٶ‬෢Ӊ໵, J. Y. Moon, ੴࢁത߃,৿ຊ޾࢘, Ӌ৔޺ޫ, ాதହ‫و‬, ੴᖒྙ, ൧ଜढ़, ߴๆѪࢠ, ৿ాߒհ, H. Wollnikʢ‫ޱ‬಄ൃදʣ,ʮMRTOF+α-TOF Λ༻͍ͨ୹ण໋ α่յ֩छͷ࣭ྔ-่յಛੑଌఆʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձʢ2020 ೥ʣ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16–19 ೔.

Awards৿େً, ʮཧ‫͚͓ʹݚ‬Δ൦෍༻ਫ਼੡ 42, 43 K ͓Αͼ 44m Sc ͷ੡଄ٕज़։ൃʯ, ୈ 56 ճΞΠιτʔϓɾ์ࣹઢ‫ൃڀݚ‬දձ एख༏लߨԋ৆, 2019 ೥ 7 ݄ 4 ೔.
N. Sato, “Awards the Element NIHONIUM”, Periodic Table of Younger Chemists, International Union of Pure and Applied Chemistry,- 350 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

July 8, 2019.
த໺‫ࢤو‬, ౦ୡ໵, Ӌ৔޺ޫ, ᴡ౻௚ਓ, দ‫ݪ‬༤ೋ, ʮઌಋతͳྔࢠϏʔϜԠ༻ʹΑΔεϚʔτͳ݈߁௕णࣾձͷ૑ग़ʯ, ಺ֳ෎ ୈ 2ճ೔ຊΦʔϓϯΠϊϕʔγϣϯେ৆೔ຊֶज़ձٞձ௕৆, 2020 ೥ 2 ݄ 15 ೔.

Press releasesࣗવքͰ࠷খͷྭ‫ى‬ΤωϧΪʔΛ΋ͭ‫֩ࢠݪ‬ঢ়ଶͷਓ޻తੜ੒ʹ੒ޭ—௒ਫ਼ີʮ‫ܭ࣌֩ࢠݪ‬ʯ࣮‫ʹݱ‬େ͖͘લਐ—, ཧԽֶ‫ڀݚ‬ॴ, 2019 ೥ 9 ݄ 11 ೔. https://www.riken.jp/press/2019/20190912_1/ .
τϦ΢Ϝ‫֩ࢠݪ‬ͷਫ਼ີϨʔβʔ෼ޫ࣮‫΁ݱ‬ॏཁͳҰา—τϦ΢Ϝ 229 ΞΠιϚʔঢ়ଶͷΤωϧΪʔΛܾఆ—, ཧԽֶ‫ॴڀݚ‬, 2019೥ 11 ݄ 29 ೔. https://www.riken.jp/press/2019/20191129_2/ .

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Accelerator Applications Research Division
RI Application Research Group
Industrial Application Research Team
1. Abstract

Industrial application research team handles non-academic activities at RIBF corresponding mainly to industries.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Support of industrial utilization of the RIBF accelerator beam.
Development of technologies related to the industrial utilization and novel industrial applications.
Fee-based distribution of radioisotopes produced at RIKEN AVF Cyclotron.
Development of real-time wear diagnostics of industrial material using RI beams.

3. Summary of Research Activity(1) Support of Industrial Utilization of RIBF
RNC promote facility-sharing program “Promotion of applications of high-energy heavy ions and RI beams.” In this program,
RNC opens a part of the RIBF facility, which includes the AVF cyclotron, RILAC, RIKEN Ring Cyclotron and experimental instruments, to non-academic proposals from users including private companies. The proposals are reviewed by a program advisorycommittee, industrial PAC (IN-PAC). The proposals which have been approved by the IN-PAC are allocated with beam times and theusers pay RIKEN the beam time fee. The intellectual properties obtained by the use of RIBF belong to the users. In order to encourage
the use of RIBF by those who are not familiar with utilization of ion beams, the first two beam times of each proposal can be assigned
to trial uses which are free of beam time fee.
In July 2019, the ninth IN-PAC met and approved two fee-based proposals from new users. In January 2019, IN-PAC held amail review and approved one fee-based proposal from a continuously using private company. In January and February 2019, fourfee-based beam times were performed with Kr-84 (70 MeV/nucleon) and Ar-40 (95 MeV/nucleon) beams at the E5A beamline. The
client used the beam to simulate single-event eﬀects of space-use semi-conductors by heavy-ion components of cosmic rays.
(2) Development of technologies related to the industrial utilization and novel industrial applications
We develop technologies to assess and improve the beam quality. Before each beam time, we measure the properties of the beam;
the dependence of the beam energy on the degrader thickness, the beam LET-distribution at a certain depth of an irradiated sample
calculated with the energy-loss code (SRIM), and the relation between the beam flux and the reading of a transmission-type detectors.
Since the beam is extracted to the atmosphere and passes through materials, it can be contaminated with secondary nuclides producedby nuclear reactions in the materials. We study the beam impurity using radiochemical measurements and compared the results withsimulations by the PHITS code. We tested radiochromic films as a new method of two-dimensional dose distribution measurement.
We have irradiated two types of radiochromic films using C, Ar, and Fe ions and measured the change of optical density as a functionof the dose. We conclude that radiochromic films can be useful to measure the dose distribution of heavy-ion irradiations with a spatial
resolution of about 1 mm.
(3) Fee-based distribution of radioisotopes produced at RIKEN AVF Cyclotron
We have been handling fee-based distribution of radioisotopes since 2007. The radionuclides are Zn-65 (T 1/2 = 244 days), Cd-109(463 days), Y-88 (107 days), Sr-85 (65 days) and Cu-67 (2.58 days) which are produced at the AVF cyclotron by the nuclear chemistryresearch team. According to a material transfer agreement (MTA) drawn between Japan Radioisotope Association (JRIA) and RIKEN,
JRIA mediates the transaction of the RIs and distributes them to users. Details can be found on the online ordering system J-RAM
home page of JRIA.
In 2019, we delivered no Cd-109, two shipments of Zn-65 with a total activity of 6.7 MBq, two of Y-88 with a total activity of
2 MBq, and one of Cu-67 with an activity of 5 MBq. The final recipients of the RIs were two universities, one research institute andone medical research center.
(4) Development of real-time wear diagnostics of industrial material using RI beams
We are developing a method to determine the spatial distribution of gamma-ray emitting RIs on periodically-moving objects,
named “GIRO” (Gamma-ray Inspection of Rotating Object), that is based on the same principle as the medical PET imaging but issimpler and less expensive. Two pairs of detectors were employed to obtain 3D image data. We also performed single-photon emission
computer tomography (SPECT) mode measurement. GIRO can obtain SPECT-mode data together with PET-mode data. This method
can be used for real-time inspection of a closed system in a running machine. In 2019, we are developing a portable size GIRO system
in order to bring and demonstrate it for private companies.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Members
Team Leader
Atsushi YOSHIDA
Contract Researcher
Tadashi KAMBARA
Technical Staﬀ I
Daiki MORI

List of Publications & Presentations
Presentations[Domestic conferences/workshops]٢ాರ (‫ޱ‬಄ൃදʣ, ʮՃ଎‫ࢪث‬ઃͰൃੜ͢ΔΠΦϯϏʔϜͷඇੜ෺‫ۀ࢈ܥ‬ར༻ʯ, ෱ҪΠΦϯϏʔϜҭछ‫ڀݚ‬ձ, ෱Ҫ‫ݝ‬ए‫ڱ‬࿷ΤωϧΪʔ‫ڀݚ‬ηϯλʔ, ರլ, 2019 ೥ 12 ݄ 13 ೔.
٢ాರ (‫ޱ‬಄ൃදʣ, ʮӉ஦࣌୅౸དྷʙ൒ಋମͰ΋ॏΠΦϯরࣹʙʯ, ཧ‫ݚ‬γϯϙδ΢ϜʮॏΠΦϯϏʔϜҭछٕज़ͷ࣮༻Խ 20 ೥ʯ,
࿨ޫ, 2020 ೥ 1 ݄ 23 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
Quantum Hadron Physics Laboratory
1. Abstract

Atomic nuclei are made of protons and neutrons bound by the exchange of pion and other mesons. Also, protons and neutrons
are made of quarks bound by the exchange of gluons. These strong interactions are governed by the non-Abelian gauge theory
called the quantum chromodynamics (QCD). On the basis of theoretical and numerical analyses of QCD, we study the interactions
between the nucleons, properties of the dense quark matter realized at the center of neutron stars, and properties of the hot quark-gluon
plasma realized in the early Universe. Strong correlations common in QCD and cold atoms are also studied theoretically to unravel
the universal features of the strongly interacting many-body systems. Developing perturbative and non-perturbative techniques inquantum field theory and string theory are of great importance not only to solve gauge theories such as QED and QCD, but also to findthe theories beyond the standard model of elementary particles. Various theoretical approaches along this line have been attempted.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Perturbative and non-perturbative methods in quantum field theories
Theory of spontaneous symmetry breaking
Lattice gauge theory
QCD under extreme conditions
Nuclear and atomic many-body problems

3. Summary of Research Activity(1) Perturbative and non-perturbative methods in quantum field theories(1-1) Theory of the Anomalous Magnetic Moment of the Electron
The anomalous magnetic moment of the electron ae measured in a Penning trap occupies a unique position among high precision
measurements of physical constants in the sense that it can be compared directly with the theoretical calculation based on the renormalized quantum electrodynamics (QED) to high orders of perturbation expansion in the fine structure constant α, with an eﬀective
parameter α/π. Both numerical and analytic evaluations of ae up to (α/π)4 were firmly established. The coeﬃcient of (α/π)5 has
been obtained recently by an extensive numerical integration. The contributions of hadronic and weak interactions have also been
estimated. The sum of all these terms leads to ae (theory) = 1 159 652 181.606 (11)(12)(229) × 10−12 , where the first two uncertainties
are from the tenth-order QED term and the hadronic term, respectively. The third and largest uncertainty comes from the current bestvalue of the fine-structure constant derived from the cesium recoil measurement: α−1 (Cs) = 137.035 999 046 (27). The discrepancy
between ae (theory) and ae ((experiment)) is 2.4σ. Assuming that the standard model is valid so that ae (theory) = ae (experiment) holds,
we obtained α−1 (ae ) = 137.035 999 1496 (13)(14)(330), which is nearly as accurate as α−1 (Cs). The uncertainties are from thetenth-order QED term, hadronic term, and the best measurement of ae , in this order.
(1-2) Optimized perturbation theory and its relation to anti-Stokes lines
We discussed fundamental properties of the fastest apparent convergence (FAC) condition which is used as a variational criterion
in optimized perturbation theory (OPT). We examine an integral representation of the FAC condition and a distribution of the zerosof the integral in a complex artificial parameter space on the basis of theory of Lefschetz thimbles. We find that the zeros accumulate
on a certain line segment known as an anti-Stokes line in the limit K → ∞, where K is a truncation order of a perturbation series.
This phenomenon gives an underlying mechanism that physical quantities calculated by OPT can be insensitive to the choice of theartificial parameter.
(1-3) Perturbative static quark potential in Maximal Abelian gauge
One of the most interesting features of QCD is its peculiar behavior at low energies, where it displays confinement. Among themany explanations proposed for this phenomenon, one of the more interesting approaches utilizes its similarity to the behavior of amagnetic field in a type II superconductor. The magnetic field cannot penetrate the superconductor except for narrow flux tubes, much
like the chromoelectric field extends only between confined particles, and if there existed elementary magnetic charges, they would
be confined inside a superconductor much like quarks in the vacuum. We calculated the static quark potential for an SU(N) gauge
theory in the Maximal Abelian gauge as well as its Abelian projection up to two loops in perturbation theory, and we discussed its
renormalization properties.
(1-4) Lorentzian conformal field theories through sine-square deformation
In quantum field theories, symmetry plays an essential and exceptional role. Focusing on some proper symmetry and delving
into its meaning have been proven to be one of the most fruitful strategies. We reexamined two-dimensional Lorentzian conformal
field theory using the formalism previously developed in a study of sine-square deformation of Euclidean conformal field theory. We
construct three types of Virasoro algebra. One of them reproduces the result by Lüscher and Mack, while another type exhibits thedivergence in the central charge term. The other leads the continuous spectrum and contains no closed time-like curve in the system.
(2) Theory of spontaneous symmetry breaking(2-1) Eﬀective Lagrangian for Nambu-Goldstone modes in nonequilibrium open systems
We developed the eﬀective field theory of diﬀusive Nambu-Goldstone (NG) modes associated with spontaneous internal symmetry
breaking taking place in nonequilibrium open systems. The eﬀective Lagrangian describing semi-classical dynamics of the NG modes- 354 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

is derived and matching conditions for low-energy coeﬃcients are also investigated. Due to new terms peculiar to open systems, theassociated NG modes show diﬀusive gapless behaviors in contrast to the propagating NG mode in closed systems. We demonstrate
two typical situations relevant to the condensed matter physics and high-energy physics, where diﬀusive type-A or type-B NG modes
appear.
(2-2) Spontaneous symmetry breaking and Nambu-Goldstone modes in open classical and quantum systems
Spontaneous symmetry breaking (SSB) in Hamiltonian systems is a universal and widely observed phenomena in nature, e.g.,
the electroweak and chiral symmetry breakings, superconductors, ferromagnets, solid crystals, and so on. It is also known that the
SSB occurs even in dissipative systems such as reaction diﬀusion system and active matters. We discussed spontaneous symmetry
breaking of open classical and quantum systems. When a continuous symmetry is spontaneously broken in an open system, a gaplessexcitation mode appears corresponding to the Nambu-Goldstone mode. Unlike isolated systems, the gapless mode is not always apropagation mode, but it is a diﬀusion one. Using the Ward-Takahashi identity and the eﬀective action formalism, we establish the
Nambu-Goldstone theorem in open systems, and derive the low-energy coeﬃcients that determine the dispersion relation of NambuGoldstone modes. Using these coeﬃcients, we classify the Nambu-Goldstone modes into four types: type-A propagation, type-A
diﬀusion, type-B propagation, and type-B diﬀusion modes.
(3) Lattice gauge theory(3-1) NΩ dibaryon from lattice QCD near the physical point
The nucleon(N)-Omega(Ω) system in the S-wave and spin-2 channel was studied from the (2+1)-flavor lattice QCD with nearly
physical quark masses. The time-dependent HAL QCD method is employed to convert the lattice QCD data of the two-baryon
correlation function to the baryon-baryon potential and eventually to the scattering observables. The potential, obtained under theassumption that its couplings to the D-wave octet-baryon pairs are small, is found to be attractive in all distances and to produce aquasi-bound state near unitarity. Including the extra Coulomb attraction, the binding energy of becomes 2.5 MeV. Such a spin-2 state
could be searched through two-particle correlations in p-p, p-nucleus and nucleus-nucleus collisions.
(3-2) ΛΛ and NΞ interactions from lattice QCD near the physical point
The S-wave ΛΛ and NΞ interactions were studied on the basis of the (2+1)-flavor lattice QCD simulations close to the physicalpoint. Lattice QCD potentials in four diﬀerent spin-isospin channels are extracted by using the coupled-channel HAL QCD method
and are parametrized by analytic functions to calculate the scattering phase shifts. The ΛΛ interaction at low energies shows only aweak attraction, which does not provide a bound or resonant dihyperon. The NΞ interaction in the spin-singlet and isospin-singlet
channel is most attractive and lead the NΞ system near unitarity. Relevance to the strangeness = −2 hypernuclei as well as to twobaryon correlations in proton-proton, proton-nucleus and nucleus-nucleus collisions was also discussed.
(3-3) Stress tensor around static quark-anti-quark from Yang-Mills gradient flow
The spatial distribution of the stress tensor around the quark-anti-quark pair in SU(3) lattice gauge theory was studied. The YangMills gradient flow plays a crucial role to make the stress tensor well-defined and derivable from the numerical simulations on thelattice. The resultant stress tensor with a decomposition into local principal axes shows, for the first time, the detailed structure of theflux tube along the longitudinal and transverse directions in a gauge invariant manner. The linear confining behavior of the potential
at long distances is derived directly from the integral of the local stress tensor.
(4) QCD under extreme conditions(4-1) Finite density QCD based on complex Langevin method
The complex Langevin method (CLM) is one of a promising approach to overcome the sign problem. The central idea of thisapproach is that the stochastic quantization does not require the probabilistic interpretation of the Boltzmann weight e−S even when theaction takes complex values. Although the equivalence between CLM and the familiar path integral quantization is quite nontrivial, it
is pointed out that the probability distribution of the drift term can judge the correctness of the CLM. This enable us to perform latticesimulation of QCD based on CLM in the finite density region in a self-contained manner. We discussed the applicability of the CLM
with four-flavor staggered fermions on a 83 × 16 lattice with quark mass m = 0.01. In particular, we focus on the behavior of theeigenvalue distribution of the fermion mass matrix which is closely related to the appearance of the singular drift problem.
(4-2) Non-equilibrium quantum transport of chiral fluids from kinetic theory
We introduced the quantum-field-theory (QFT) derivation of chiral kinetic theory (CKT) from the Wigner-function approach,which manifests side jumps and non-scalar distribution functions associated with Lorentz covariance and incorporates both backgroundfields and collisions. The formalism is utilized to investigate second-order responses of chiral fluids near local equilibrium. Such nonequilibrium anomalous transport is dissipative and aﬀected by interactions. Contributions from both quantum corrections in anomaloushydrodynamic equations (EOM) of motion and those from the CKT and Wigner functions (WF) are considered in a relaxation-time
approximation (RTA). Anomalous charged Hall currents engendered by background electric fields and temperature/chemical-potential
gradients are obtained. Furthermore, chiral magnetic/vortical eﬀects (CME/CVE) receive viscous corrections as non-equilibrium
modifications stemming from the interplay between side jumps, magnetic-moment coupling, and chiral anomaly.
(4-3) Hadron-quark crossover in cold and hot neutron stars
We presented a much improved equation of state for neutron star matter, QHC19, with a smooth crossover from the hadronic
regime at lower densities to the quark regime at higher densities. We now use the Togashi et al. equation of state, a generalization of
the Akmal-Pandharipande-Ravenhall equation of state of uniform nuclear matter, in the entire hadronic regime; the Togashi equation ofstate consistently describes nonuniform as well as uniform matter, and matter at beta equilibrium without the need for an interpolation
between pure neutron and symmetric nuclear matter. We describe the quark matter regime at higher densities with the Nambu-Jona-- 355 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Lasinio model, now identifying tight constraints on the phenomenological universal vector repulsion between quarks and the pairing
interaction between quarks arising from the requirements of thermodynamic stability and causal propagation of sound. The resultant
neutron star properties agree very well with the inferences of the LIGO/Virgo collaboration, from GW170817, of the pressure versus
baryon density, neutron star radii, and tidal deformabilities. The maximum neutron star mass allowed by QHC19 is 2.35 MS, consistent
with all neutron star mass determinations.
(5) Nuclear and atomic many-body problems(5-1) Renormalized random-phase approximation
A fully self-consistent renormalized random-phase approximation was constructed based on the self-consistent Hartree-Fockmean field plus exact pairing solutions (EP). This approach exactly conserves the particle number and restores the energy-weighted
sum rule, which is violated in the conventional renormalized particle-hole random-phase approximation for a given multipolarity. The
numerical calculations are carried out for several light-, medium-, and heavy-mass nuclei such as O22, Ni60, and Zr90 by using theeﬀective MSk3 interaction. To study the pygmy dipole resonance (PDR), the calculations are also performed for the two light andneutron-rich O24,28 isotopes, whose PDRs are known to be dominant. The results obtained show that the inclusion of ground-statecorrelations beyond the random-phase approximation (RPA) by means of the occupation numbers obtained from the EP aﬀects the
RPA solutions within the whole mass range, although this eﬀect decreases with increasing the mass number. At the same time, theantipairing eﬀect is observed via a significant reduction of pairing in neutron-rich nuclei. The enhancement of PDR is found in mostneutron-rich nuclei under consideration within our method.
(5-2) Ab initio covariant density functional theory for nuclear structure
Nuclear structure models built from phenomenological mean fields, the eﬀective nucleon-nucleon interactions (or Lagrangians),
and the realistic bare nucleon-nucleon interactions were presented. The success of covariant density functional theory (CDFT) to
describe nuclear properties and its influence on Brueckner theory within the relativistic framework are focused upon. The challenges
and ambiguities of predictions for unstable nuclei without data or for high-density nuclear matter, arising from relativistic density
functionals, are discussed. The basic ideas in building an ab initio relativistic density functional for nuclear structure from ab initio
calculations with realistic nucleon-nucleon interactions for both nuclear matter and finite nuclei are presented. The current statusof fully self-consistent relativistic Brueckner-Hartree-Fock (RBHF) calculations for finite nuclei or neutron drops (ideal systems
composed of a finite number of neutrons and confined within an external field) is reviewed. The guidance and perspectives towards an
ab initio covariant density functional theory for nuclear structure derived from the RBHF results are provided.
(5-3) QCD-like phase diagram with Efimov trimers and Cooper pairs
We investigated color superfluidity and trimer formation in resonantly interacting SU(3) Fermi gases with a finite interaction
range. The finite range is crucial to avoid the Thomas collapse and treat the Efimov eﬀect occurring in this system. Using theSkorniakov-Ter-Martirosian equation with medium eﬀects, we show the eﬀects of the atomic Fermi distribution on the Efimov trimer
energy at finite temperature. We show the critical temperature of color superfluidity within the many-body T-matrix approximation.
In this way, we can provide a first insight into the phase diagram as a function of the temperature T and the chemical potential µ.
This phase diagram consists of trimer, normal, and color-superfluid phases, and is similar to that of quantum chromodynamics at finite
density and temperature.
(5-4) Superfluid phase transitions in asymmetric nuclear matter
We investigated superfluid phase transitions of asymmetric nuclear matter at finite temperature (T) and density (ρ) with a low
proton fraction (Y p ≤ 0.2), which is relevant to the inner crust and outer core of neutron stars. A strong-coupling theory developed
for two-component atomic Fermi gases is generalized to the four-component case, and is applied to the system of spin-1/2 neutronsand protons. The phase shifts of neutron-neutron (nn), proton-proton (pp) and neutron-proton (np) interactions up to k = 2 fm−1 areCof the neutron superfluidity at Y p = 0 agrees
described by multi-rank separable potentials. We show that the critical temperature T nn
Cwell with Monte Carlo data at low densities and takes a maximum value T nn = 1.68 MeV at ρ/ρ0 = 0.14 with ρ0 = 0.17 fm−3 . Also,Cof the proton superconductivity for Y p ≤ 0.2 is substantially suppressed at low densities due to np-pairing
the critical temperature T nn
C
only above ρ/ρ0 = 0.70(0.77) for Y p = 0.1(0.2), and (iii) the deuteron condensation
fluctuations, and starts to dominate over T nn
temperature T dC is suppressed at Y p ≤ 0.2 due to a large mismatch of the two Fermi surfaces.
(5-5) One-dimensional Bose and Fermi gases with contact interactions
One-dimensional spinless Bose and Fermi gases with contact interactions have the close relationship via Girardeau’s Bose-Fermi
mapping, leading to the correspondences in their energy spectra and thermodynamics. However, correlation functions are in general
not identical between these systems. We derive in both systems the universal relations for correlation functions, which hold for any
energy eigenstate and any statistical ensemble of the eigenstates. These relations include the large-momentum tails of static structure
factors and of momentum distributions as well as energy relations, which connect the sums of kinetic and interaction energies to themomentum distributions. The relations involve two- and three-body contacts, which measure local two- and three-body correlations,
respectively. We clarified how the relations for bosons and fermions diﬀer and are connected with each other. In particular, we foundthat the three-body contact makes no contribution to the bosonic energy relation, but it plays a crucial role in fermionic one.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Members
Director
Tetsuo HATSUDA
Vice Chief Scientist
Tsukasa TADA
Research/Technical Scientists
Takumi DOI (Senior Research Scientist)
Yoshimasa HIDAKA (Senior Research Scientist)

Pascal Raphaël Gabriel NAIDON (Senior Research Scientist)
Haozhao LIANG (Senior Research Scientist)

Senior Scientist
Makiko NIO
Contract Researcher
Dang NGUYEN DINH
Special Postdoctoral Researchers
Tomoya HAYATA
Matthias W.G. BERWEIN
Takahiro DOI
Shinya GONGYO

Kazuya MAMEDA
Enrico RINALDI
Shoichiro TSUTSUI

Postdoctoral Researcher
Christiane Heike SCHMICKLER
Research Consultant
Takeo INAMI (Sungkyunkwan Univ. (SKKU))
Visiting Scientists
Shinya AOKI (Kyoto Univ.)
Tatsumi AOYAMA (KEK)
Gergely P. FEJOS (Eotvos Lorand Univ.)
Kenji FUKUSHIMA (Univ. of Tokyo)
Hideki HAMAGAKI (Nagasaki Inst. of Applied Sci.)
Koji HASHIMOTO (Osaka Univ.)
Masashi HAYAKAWA (Nagoya Univ.)
Tomoya HAYATA (Keio Univ.)
Yoichi IKEDA (Kyushu Univ.)
Takashi INOUE (Nihon Univ.)
Noriyoshi ISHII (Osaka Univ.)
Yoichi KAZAMA (Univ. of Tokyo)
Ivan KOSTOV (Inst. de Phys. Theorique)Tetsuo MATSUI (The Open Univ. of Japan)
Takayuki MATSUKI (Tokyo Kasei Univ.)
Takaya MIYAMOTO (NEC Corporation)
Kenji MORITA (QST)

Masaki MURATA (Japan Univ. Economics)
Atsushi NAKAMURA (Hiroshima Univ.)
Takashi NAKATSUKASA (Tsukuba Univ.)
Hung NGUYEN (Duy Tan Univ.)
Yoji OHASHI (Keio Univ.)
RHINE KUMAR ARAYAKKANDI KEECH (Cochin Univ. ofSci. and Tech.)
Norisuke SAKAI (Keio Univ.)
Kenji SASAKI (Kyoto Univ.)
Shoichi SASAKI (Tohoku Univ.)
Hiroshi SUZUKI (Kyushu Univ.)
Motoi TACHIBANA (Saga Univ.)
Sachiko TAKEUCHI (Japan College of Social Work)
Makoto TAKIZAWA (Showa Pharmaceutical Univ.)
Hiroshi TOKI (Osaka Univ.)
Di-Lun YANG (Keio Univ.)

Visiting Researchers
Yuta SEKINO (JSPS)

Hiroyuki TAJIMA (Kochi Univ.)

Student Trainees
Yutaro AKAHOSHI (Kyoto Univ.)
Asahi CHIKAOKA (Univ. of Tokyo)
Yixin GUO (Univ. of Tokyo)
Xun LIU (Univ. of Tokyo)
Yan LYU (Peking Univ.)
Kotaro MURAKAMI (Kyoto Univ.)

Tomoya NAITO (Univ. of Tokyo)
Hikaru SAKAKIBARA (Univ. of Tokyo)
Ziting SUN (Univ. of Sci. and Tech. of China)
Hui TONG (Peking Univ.)
Zhenyu WANG (Nankai Univ.)
Tingyu ZHANG (Univ. of Sci. and Tech. of China)- 357 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
Strangeness Nuclear Physics Laboratory
1. Abstract

We proposed accurate calculation method called ‘Gaussian Expansion Method using infinitesimally shifted Gaussian lobe basis
function.’ When one proceeds to four-body systems, calculation of the Hamiltonian matrix elements becomes much laborious. In orderto make the four-body calculation tractable even for complicated interactions, the infinitesimally-shifted Gaussian lobe basis function
has been proposed. The GEM with the technique of infinitesimally-shifted Gaussians has been applied to various three-, four- andfive-body calculations in hypernuclei, the four-nucleon systems, and cold-atom systems. As results, we succeeded in extracting newunderstandings in various fields.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Hypernuclear structure from the view point of few-body problem
Structure of exotic hadron system
quantum atomic system and ultra cold atomic system
Equation of state for neutron star

3. Summary of Research Activity(1) With use of ΞN interaction based on HAL Lattice QCD, we predict to have a bound state for NN Ξ four-body system which
would be the lightest bound Ξ hypernucleus. We also propose how to produce this hypernucleus.
(2) Several compact ssscc-bar pentaquark resonances are predicted quark model, that is, J π = 1/2− ‘E = 5180 MeV, Γ =20 MeV), 5/2− (5645 MeV, 30 MeV), 5/2− (5670 MeV, 50 MeV), and 1/2+ (5360 MeV, 80 MeV). These are the candidatesof compact pentaquark resonance states from the current best quark model, which should be confirmed either by experiments
or lattice QCD calculations.
(3) Mixtures of two kinds of fermions, such as spin up and down electrons in materials, are well-known to lead to pairing andsuperconductivity. In this project, study mixtures of three diﬀerent kinds of fermions were studied. In these systems, inaddition to pairing, a new kind of clustering by three can appear due the Efimov eﬀect. We obtained the phase diagram ofthese systems and showed that it is similar to that of QCD, where the hadron phase is the analogue of the phase of Efimovclusters of three fermions.

Members
Director
Emiko HIYAMA
Research/Technical Scientists
Pascal NAIDON (Senior Research Scientist)
Special Postdoctoral Researcher /Contract Researcher
Yasuhiro YAMAGUCHISpecial Postdoctoral Researcher
Kadir Utku CAN Takuma YAMASHITA
Postdoctoral Researcher
Christiane H. SCHMICKLER
Senior Visiting Scientist
Makoto OKA (JAEA)
Visiting Scientists
Masayuki ASAKAWA (Osaka Univ.)
Kadir Utku CAN (The Univ. of Adelaide)
Jaume CARBONELL (CNRS/IN2P3, IJCLab)
Lorenzo CONTESSI (Hebrew Univ. of Jerusalem)
Jiwei CUI (Xidian Univ.)
Akinobu DOTE (KEK)
Shimpei ENDO (Tohoku Univ.)
Tomokazu FUKUDA (Univ. of Electro-Commun.)
Yasuro FUNAKI (Kanto Gakuin Univ.)
Takenori FURUMOTO (Yokohama Nat’l Univ.)
Philipp GUBLER (JAEA)

Satoru HIRENZAKI (Nara Women’s Univ.)
Atsushi HOSAKA (Osaka Univ.)
Jinniu HU (Nankai Univ.)
Tetsuo HYODO (Tokyo Metropolitan Univ.)
Kiyomi IKEDA (Niigata Univ.)
Masahiro ISAKA (Hosei Univ.)
Souichi ISHIKAWA (Hosei Univ.)
Daisuke JIDO (Tokyo Tech)
Hyun-Chul KIM (Inha Univ.)
Kei KOTAKE (Fukuoka Univ.)
Toshio MOTOBA (Univ. of Electro-Commun.)- 358 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Takayuki MYO (Osaka Inst. of Tech.)
Satoshi NAKAMURA (Tohoku Univ.)
Kazuma NAKAZAWA (Gifu Univ.)
Hidekatsu NEMURA (Osaka Univ.)
Jean-Marc RICHARD (Univ. Lyon)
Thomas RIJKEN (Univ. Of Nijmegen)Hans-Josef SCHULZE (INFN)
Shoji SHINMURA (Gifu Univ.)
Jirina STONE (Univ. of Tennessee)
Hajime TOGASHI (Kyushu Univ.)
Atsushi UMEYA (Nippon Inst. of Tech.)

Shin WATANABE (NIT, Gifu College)
Wolfram WEISE (TU Munich)Chengjun XIA (Zhejiang Univ.)
Masanobu YAHIRO (Kyushu Univ.)
Ulugbek YAKHSHIEV (Inha Univ.)
Taiichi YAMADA (Kanto Gakuin Univ.)
Yasuo YAMAMOTO (Tsuru Univ.)
Takuma YAMASHITA (Tohoku Univ.)
Ying ZHANG (Tianjin Univ.)
Xian-Rong ZHOU (East China Normal Univ.)

Student Trainees
Kongyi HU (Nankai Univ.)
Jehee LEE (Tokyo Tech)
Jie LIU (Nanjing Univ.)

Qi MENG (Nanjing Univ.)
Qian WU (Nanjing Univ.)

Part-time Worker
Yoko FUJITA (Administrative Part-time Worker I)

List of Publications & Presentations
Publications[Original papers]
J. Lee, Q. Wu, Y. Funaki, and E. Hiyama, “Three-Body structure of Λ9 Be with ααΛ cluster model,” Few-Body Syst. 60, 30 (2019).
R. Lazauskas, E. Hiyama, and J. Carbonell, “Ab initio calculation of 5 H resonant states,” Phys. Lett. B 791, 335 (2019).
J. Lee, N. Yamanaka, and E. Hiyama, “Eﬀect of the Pauli exclusion principle in the electric dipole moment of 9 Be with |∆S | = 1
interactions,” Phys. Rev. C 99, 055503 (2019).
E. Hiyama, R. Lazauskas, F. M. Marques, and J. Carbonell, “Modeling 19 B as a 17 B-n-n three-body system in the unitary limit,” Phys.
Rev. C 100, 011603(R) (2019).
T. -W. Wu, M. -Z. Liu, L. -S. Geng, E. Hiyama, and M. P. Valderrama, “DK, DDK and DDDK molecules-understanding the nature of theD∗s0 (2317),” Phys. Rev. D 100, 034209 (2019).
E. Hiyama, K. Sasaki, T. Miyamaoto, T. Doi, T. Hatsuda, Y. Yamamoto, and T. Rijken, “Possible lightes Ξ hypernuceus with Modern ΞNinteraction,” Phys. Rev. Lett. 124, 092501 (2020).
Y. Shimizu, Y. Yamaguchi, and M. Harada, “Heavy quark spin multiplet structure of Pc(4312), Pc(4440), and Pc(4457),”
arXiv:1904.00587 [hep-ph] (2019).
Y. Yamaguchi, H. G.- Tecocoatzi, A. Giachino, A. Hosaka, E. Santopinto, S. Takeuchi, and M. Takizawa, “Pc pentaquarks with chiraltensor and quark dynamics,” Phys. Rev. D 101, 091502 (2020).
Y. Yamaguchi and N. Yamanaka, “Large electric dipole moment of charged leptons in the standard model,” arXiv:2003.08195 [hep-ph](2020).
Q. Meng, E. Hiyama, K. U. Can, P. Gubler, M. Oka, A. Hosaka, and H. Zong, “Compact ssscc pentaquark states predicted by a quark
model,” Phys. Lett. B 798, 135028 (2019).
P. Froelich, T. Yamashita, Y. Kino, S. Jonsell, E. Hiyama, and K. Piszczatowski, “Four-body treatment of the antihydrogen-positronium
system: binding, structure, resonant states and collisions,” Hyperfine Interact. 240, 46 (2019).

[Review articles]
Y. Yamaguchi, A. Hosaka, S. Takeuchi, and M. Takizawa, “Heavy hadronic molecules with pion exchange and quark core couplings: a
guide for practitioners,” J. Phys. G 47, 053001 (2020).

[Proceedings]
Y. Yamaguchi, “pi J/psi-DDbar* potential described by the quark exchange diagram,” EPJ Web Conf. 204, 01007 (2019).
Y. Yamaguchi, “Short range interaction in pi J/psi-DDbar* channel,” Int. J. Mod. Phys. Conf. Ser. 49, 1960005 (2019).
Y. Yamaguchi, “Short range pi J/psi -DDbar* potential described by the quark exchange diagram,” Springer Proc. Phys. 238, 629 (2020).

Presentations[International conferences/workshops]
E. Hiyama (invited), “Five-body structure of sssc c,” The 1st CENuM Workshop for Hadron Physics, Incheon, Korea, June 17–18, 2019.
E. Hiyama (invited), “Structure of light Ξhypernuclei with modern ΞN interaction,” International workshop on “Nuclear structure at thecrossroads” (INT 19-2a), Seattle, U.S.A., July 1–August 2, 2019.
E. Hiyama (invited), “Five-body structure of sssc c,” International Workshop on Perspectives in Hadron Physics, Quy Nhon, Vietnam,
September 22–28, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

P. Naidon (Invited), “A bubble of polarons,” 2nd workshop “Clusters in quantum systems: from atoms to nuclei and hadrons,” Fukuoka,
Japan, January 27–31, 2020.
Y. Yamaguchi (oral), “Role of the tensor force in the heavy hadronic molecules,” The 18th International Conference on Hadron Spectroscopy and Structure (HADRON2019), Guilin, China, August 16–21, 2019.
Y. Yamaguchi (oral), “Tensor force in heavy hadronic molecules,” Workshop on Chiral and heavy quark symmetries in quark-hadron
physics, Osaka, Japan, August 25, 2019.
Y. Yamaguchi (oral), “Hadronic molecules of heavy hadrons with tensor force,” The 24th European conference on few-body problems inphysics (EFB24), Guirford, UK, September 2–6, 2019.
Y. Yamaguchi (oral), “Heavy hadronic molecules: pion exchange and coupling to multiquark states,” Workshop on “Physics of heavyquark and exotic hadrons,” Tokai, Ibaraki, Japan, January 27–29, 2020.
Y. Yamaguchi (oral/poster), “Tensor force in the heavy hadronic molecules,” REIMEI Workshop on Universal Features of Quantum Flows
with Spin, Orbital and Tensor Correlations, Tokai, Ibaraki, Japan, February 17–19, 2020.
K. U. Can (oral), “Structure of the charmed baryons through an electromagnetic perspective,” 15th Rencontres du Vietnam Perspectives
in Hadron Physics, ICISE, Quy Nhon, Vietnam, September 22–28, 2019.
T. Yamashita, Y. Kino, E. Hiyama, S. Jonsell, and P. Froelich (poster), “Inelastic resonant scattering of positronium by (anti)hydrogenatom,” XX International Workshop on Low-Energy Positron and Positronium Physics & XXI International Symposium on ElectronMolecule Collisions and Swarms, Belgrade, Serbia, July 18–20, 2019.
T. Yamashita, Y. Kino, E. Hiyama, K. Piszczatowski, S. Jonsell, and P. Froelich (oral, hot topic), “Towards prediction of the rates ofantihydrogen positive ion production in antihydrogen-excited positronium reaction,” XXXIst International Conference on Photonic,
Electronic, and Atomic Collisions (ICPEAC), Deauville, France, July 23–30, 2019.
M. Niiyama, T. Yamashita, and Y. Kino (poster), “Four-body calculation of energy levels of muonic molecule dtµe in muon catalyzed
fusion,” XXXIst International Conference on Photonic, Electronic, and Atomic Collisions, Deauville, France, July 23–30, 2019.
T. Yamashita, M. Umair, Y. Kino, and E. Hiyama (poster), “Coupled rearrangement channel calculation of dipole resonance states of
positronic helium atom,” XXXIst International Conference on Photonic, Electronic, and Atomic Collisions, Deauville, France, July
23–30, 2019.
C. H. Schmickler (oral), “Universal few-body physics of charged particles,” REIMEI Workshop on “Universal features of quantum flows
with spin, orbital and tensor correlations,” Tokai, Ibaraki, Japan, February 17–19, 2020.

[Domestic conferences/workshops]ࢁ‫ޱ( ޺߁ޱ‬಄ൃද), ʮύΠΦϯަ‫ͱྗ׵‬ϋυϩϯ෼ࢠঢ়ଶʯ, ‫ڀݚ‬ձʮΫΥʔΫ໛‫͔ܕ‬ΒΈͨΤΩκνοΫϋυϩϯ‫ڀݚ‬ͷਐలͱ
QCD ͷ৽ల։ʯ, ࿨ޫ, 2019 ೥ 7 ݄ 6 ೔.
ࢁ‫ޱ( ޺߁ޱ‬಄ൃද), ʮ2 ϝιϯ‫͚͓ʹܥ‬ΔϔϏʔϑϨʔόʔަ‫׵‬૬‫༻࡞ޓ‬ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄
17–20 ೔.
ࢁ‫ޱ( ޺߁ޱ‬಄ൃද), ʮిࢠͷి‫ؾ‬૒‫ࢠۃ‬Ϟʔϝϯτʹ͓͚Δϋυϩϯϧʔϓͷ‫د‬༩ʯ, Flavor Physics Workshop 2019, ෋ాྛ, 2019೥ 11 ݄ 19–22 ೔.

[Seminars]
Y. Yamaguchi, “Heavy hadronic molecules: pion exchange and coupling to compact states,” Tokyo Institute of Technology, Tokyo,
December 13, 2019.
Y. Yamaguchi, “Heavy hadronic molecules: pion exchange and coupling to compact states,” Nagoya University, Nagoya, Aichi, Japan,
December 17, 2019.
T. Yamashita and Y. Kino (oral), “For analysis of fundamental muonic atom process: development of few-body calculation method andrelated topics on relativistic eﬀects of exotic atoms,” Seminar on fundamental theories for negative muon experiments at J-PARC and
its application to elemental analysis, Tokai, Ibaraki, Japan, April 18, 2019.

Awardsංࢁӵඒࢠ, Պֶٕज़෼໺ͷจ෦Պֶେਉදজ Պֶٕज़৆ʢ‫ڀݚ‬෦໳ʣʮྔࢠগ਺ଟମ‫ܥ‬ͷ‫ࢉܭີݫ‬ཧ࿦ͷཱ֬ͱͦͷԠ༻‫ڀݚ‬ʯ,2019 ೥ 4 ݄ 17 ೔.

Press releasesංࢁӵඒࢠࣨ௕, ౔Ҫୖ਎ઐ೚‫ڀݚ‬һ, ਺ཧ૑଄ϓϩάϥϜͷॳా఩உϓϩάϥϜσΟϨΫλʔΒͷࠃࡍ‫ڞ‬ಉ‫ڀݚ‬άϧʔϓ, ৽ͨͳϋΠύʔ‫֩ࢠݪ‬ʮάβΠɾςτϥόϦΦϯʯ—άβΠཻࢠͷৼΔ෣͍Λਫ਼ີ‫Ͱࢉܭ‬ղ͖໌͔͢—, 2020 ೥ 3 ݄ 5 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
Radiation Laboratory
1. Abstract

Nucleons, such as protons and neutrons, are a bound state of constituent quarks glued together with gluons. The detail structureof nucleons, however, is not well understood yet. Especially the mechanism to build up the spin of proton, which is 1/2, is a major
problem in physics of the strong force. The research goal of Radiation Laboratory is to solve this fundamental question using the world
first polarized-proton collider, realized at RHIC in Brookhaven National Laboratory (BNL) in USA. RHIC stands for Relativistic
Heavy Ion Collider, aiming also to create Quark Gluon Plasma, the state of Universe just after the Big Bang, and study its property.
RIKEN-BNL Research Center (RBRC) also directed by H. En’yo carries our core team at BNL for those exciting researches using thePHENIX detector and its upgraded sPHENIX detector in preparation. We have observed that the proton spin carried by gluons is finite
and indeed sizable. We also identified W bosons in the electron/positron decay channel and in the muon decay channel, with which we
showed how much anti-quarks carry the proton spin. Other than the activities at RHIC we are preparing and starting new experiments
at J-PARC and Fermilab to study the nature of hadron and preparing for the electron-ion collider (EIC). We are also performing
technical developments such as novel ion sources, fine-pitch silicon pixel detectors and high-performance trigger electronics.

2. Major Research Subjects(1) Spin physics with relativistic polarized-proton collisions at RHIC
(2) Study of nuclear matter at high temperature and/or at high density(3) Technical developments on radiation detectors and accelerators

3. Summary of Research Activity(1) Experimental study of spin structure of proton using RHIC polarized proton collider[See also RIKEN-BNL Research Center Experimental Group for the activities at BNL]
The previously published central neutral pion double spin asymmetries at the highest collision energies at RHIC of 510 GeV havebeen augmented with the publication of the complementary charged pion double spin asymmetries at the same collision energy. The
ordering of the three pion asymmetries allows a direct determination of the sign of the gluon polarization which has been found to benonzero. These results will be included in future global fits of all the existing experimental data in the world and will improve thesensitivity of quark and gluon spin contributions to the total spin of the nucleon. Additionally, the first double spin asymmetry resultsfor direct photons and jets are being prepared by PHENIX. Both are in principle cleaner probes since no fragmentation functions are
involved. The direct photon probe also restricts the initial, hard interaction to be predominantly between a quark and a gluon thus
further increasing the sensitivity to the gluon spin.
While orbital angular momentum cannot be directly accessed at RHIC, several transverse spin phenomena have been observed
which relate to orbital angular momentum and the three-dimensional structure of the nucleon. These phenomena by themselves havebecome a major field of research as the dynamics of the strong interaction. During the 2015 RHIC operation, collisions of transversely
polarized protons with Au and Al nuclei were provided for the first time. Two rather surprising results have been discovered here.
First, the single transverse spin asymmetries for J/Ψ particles which are found to be consistent with zero to even higher precisions,show distinctly nonzero asymmetries in proton-Au collisions at the lowest transverse momenta both if detected at slightly forward
or backward regions with respect to the polarized beam. Also charged hadron single spin asymmetries have been observed in all
three colliding systems. While a previously known nonzero forward asymmetry for positive hadrons was confirmed, a substantial
reduction of these asymmetries for p + Al and p + Au collisions was observed. Such a reduction was predicted by several theoreticalmodels describing the non-linear eﬀects of high gluon densities in nuclei suggested by the so-called color-glass-condensate. While
the kinematic region does not reach into the range where the color-glass-condensate is expected, this reduction in asymmetries has
been met with interest by the theory community. The results have now been published. When moving to more central rapidities, theleft-right asymmetries are known to be very small for neutral pions. Since then they have been confirmed to be small also for eta
mesons and, for the first time, also for direct photons. The direct photon asymmetries are again very important here as they are only
sensitive to the transverse spin eﬀects in the initial state and not the fragmentation. Both results are being prepared for publication.
In June of 2017, an electro-magnetic calorimeter was installed in the most forward area of the STAR experiment and took polarized
proton collision data for neutral particle production (neutron, photon, neutral pion). The cross-section measurement will give us new
inputs to develop high-energy particle-collision models which are essential to understand air-shower from ultra-high energy cosmic
rays. The asymmetry measurement will enable us to understand the hadron collision mechanism based on QCD. An unexpectedly
large neutral pion asymmetry has been found using this data that may connect to the large pion asymmetries at smaller rapidities andhigher transverse momenta. The results have been accepted for publication in PRL.
Some of us are participating in the Fermilab SeaQuest experiment as a pilot measurement of muon pairs from Drell-Yan processusing a 120-GeV unpolarized proton at Fermilab. After finishing unpolarized measurements in 2017 to study the quark spin-orbit
eﬀect, a new measurement with a polarized proton target will start in 2020 to study the sea-quark orbit eﬀect of the polarized protonin the target.
For many jet related measurements fragmentation functions are necessary to gain spin and or flavor sensitivity. Those are currently
extracted by some of us using the KEK-Belle data. In addition to using the fragmentation results with RHIC measurements, they will
also provide the basis for most of the key measurements to be performed at the electron-ion collider. In 2019, transverse momentum- 361 -

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dependent cross sections of pions, kaons and protons were published as a function of fractional energy and event topology. These
measurements relate to essentially all transverse spin or momentum dependent measurements at RHIC, semi-inclusive DIS and theEIC.
As the Electron-Ion Collider is becoming a reality, many of us are participating in the various community eﬀorts to define thephysics goals of the EIC and how they inform on the choices of collisions energies, luminosities and detector components. While theaccelerator eﬀorts are naturally led by the two main Nuclear physics laboratories in the US, BNL and JLAB, a large EIC user groupof more than 1000 members from all around the world is working on making the EIC a reality. Within this group, we are participatingin various functions from the steering committee, the conference and talks committee to various physics or detector related topicalgroups.
(2) Experimental study of quark-gluon plasma using RHIC heavy ion collider[See also RIKEN-BNL Research Center Experimental Group for the activities at BNL]
We have completed several key measurements in the study of quark-gluon plasma at RHIC. As the top of them, we lead theanalysis of the first thermal photon measurement in heavy ion collisions. The measurement indicates that the initial temperaturereached in the central Au + Au collision at 200 GeV is about 350 MeV, far above the expected transition temperature T c ∼ 170 MeV,
from hadronic phase to quark-gluon plasma. This work was rewarded by Nishina Memorial Prize given to Y. Akiba in 2011. We alsomeasured direct photons in d + Au and direct photon flow strength ν2 and ν3 in Au + Au.
We lead measurement of heavy quark (charm and bottom) using VTX, a 4-layer silicon vertex tracker which we jointly constructedwith US DOE. The detector was installed in PHENIX in 2011. PHENIX recorded approximately 10 times more data of Au+Au
collisions in the 2014 run than the 2011 run. PHENIX recorded high statistics p + p and p + A data in 2015, and the doubled the Au+ Au in 2016. PHENIX concluded its data taking in the 2016 run.
The results of the 2011 run was published in Physical Review C (Phys. Rev. C 93, 034904 (2016)). This is the first publicationfrom VTX. The result showed that the electrons from bottom quark decay is suppressed for pT > 4 GeV/c, but the suppression factor issmaller than that of charm decay electrons for 3 < pT < 4 GeV/c. This is the first observation of bottom electron suppression in heavy
ion collisions, and the first result that shows the bottom and charm suppression is diﬀerent. The results of b→e and c→e measurementin the 2015 p + p run has been published in Physical Review D99, 092003 (2019). The centrality dependence of the suppression b→e
and c→e from the 2014 Au+Au data is in preparation.
PHENIX published measurements of flow strength in p + Au, d + Au, and 3 He+Au (Nature Physics 15, 214 (2019)). The results
provide strong evidence for formation of small droplet of quark gluon plasma in collisions of small systems at RHIC.
In Wako we are operating a cluster computer system (CCJ) specialized to analyze huge data sets taken with the PHENIX detector.
It consists of 28 nodes (18 old nodes and 10 new nodes) each of which has two CPUs and 10 sets of local disks for data repository(old node: quad-core CPU, 1TB disk, new node: six-core CPU, 2 TB disk). There are 264 CPU cores and 380 TB disks in total.
This configuration ensures the fastest disk I/O when each job is assigned to the node where the required data sets are stored. It is also
important that this scheme doesn’t require an expensive RAID system and network. Through this development we have established afast and cost-eﬀective solution in analyzing massive data.
The data of 0.9 Pbyte obtained by the PHENIX experiment is stored in a hierarchical storage system which is a part of HOKUSAI
BigWaterfall/SailingShip supercomputer systems operated by the Head Oﬃce for Information Systems and Cybersecurity. In addition,
we operate a dedicated server for the RHICf group and two servers for the J-PARC E16 group, to keep their dedicated compilationand library environments, and some data.
(3) Study of properties of mesons and exotic hadrons with domestic accelerators
Preparation of the experiment E16 at J-PARC Hadron experimental facility is underway with several Grant-in-Aids. This experiment aims to perform a systematic study of the spectral modification of low-mass vector mesons in nuclei to explore the physics ofchiral symmetry breaking and restoration in dense nuclear matter, namely, the mechanism proposed by Nambu to generate most of
hadron masses.
The Gas Electron Multiplier (GEM) technology is adopted for the two key detectors, GEM Tracker (GTR) and Hadron-blind
Cherenkov detector (HBD). To improve electron-identification performance, lead-glass calorimeters (LG) are used in combination
with HBD. We are in the production phase. The parts for six modules of GTR, four modules of HBD and six modules of LG are
assembled and installed in the spectrometer magnet at J-PARC. Read-out electronics and trigger logic modules are also installed andtested. We have been a member of the CERN-RD51 collaboration to acquire the read-out technology for GEM. The MoU for RD51
was extended for the period of 2019–2023.
Due to the budgetary limitation, we aim to install a part of detectors at the beginning of the experiment, eight modules of
GTR/HBD/LG out of 26 modules in the full installation. J-PARC PAC gave us a stage-2 approval on July 2017, to the commissioning run (Run 0), which will be performed when the beam line is completed. Although there is a significant delay from theoriginally planned date of March 2016, the construction of the beam line by KEK was completed finally in early 2020 to perform
this experiment. We performed the 1st half of commissioning run (Run0a) in June 2020 successfully, and the 2nd half is planned in
January 2021.
(4) Detector development for PHENIX experiment
The PHENIX experiment proposes substantial detector upgrades to go along the expected accelerator improvements, including
the future electron-ion collider “EIC”. The present PHENIX detector is repurposed to the sPHENIX (super PHENIX) detector whichreuses the Babar solenoid magnet at SLAC and is covered by the hadronic calorimeter which was not available in the previous RHIC

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experiments. The sPHENIX was approved for the Project Decision-2/3 (corresponds to DOE’s Critical Decision-2/3) in May 2019.
We RIKEN group have been developing the one of the tracking devices of sPHENIX detector, so called intermediate tracker (INTT)
since 2015. The INTT provides the best timing resolution among the sPHENIX tracking system, in conjunction with a time projection
chamber and a MAPS based vertex detectors. The R&D of INTT detector is almost in the last stage. The prototype detectors
demonstrated satisfactory performance in the eﬃciency and position resolutions as designed in the last two beam tests at the Fermilab
Test Beam Facility (FTBF) using 120 GeV proton beam in March 2018 and June 2019. The preparation for the production ladderassembly is ongoing both in Taiwan Silicon Detector Facility (TSiDF) and BNL.
We have been developing a plan to build a forward spectrometer to be added to the sPHENIX detector. With this addition, thefsPHENIX detector will have both hadronic and electromagnetic calorimetry as well as tracking in the forward rapidity region. This
upgrade makes it possible to study forward jets and hadrons in jets which are of vital importance for the cold QCD program inpolarized p + p and p + A collisions at RHIC. The fsPHENIX detector can be further upgraded to the ePHENIX detector to be used
for electron-ion collisions at EIC. We are preparing test bench to perform R&D for the forward hadron calorimeter.
As the further investigation of the neutral pion production asymmetry discovered in the RHICf experiment, we started preparation
for the next phase of the experiment, namely RHICf-II. The target year of physics data taking is 2024 as a part of sPHENIX experiment.
The highlight of the upgraded experiment is the larger acceptance of the high position resolution part of the zero-degree calorimeter(ZDC). We found the detector technology developed for the FoCAL upgrade project of the ALICE experiment at LHC well satisfies
the RHICf-II performance requirement. We thus resumed the associated membership of the ALICE collaboration and the RHICf-II
detectors are to be developed together with the FoCAL collaboration. This new detector technology development is also a part of the
R&D program for the essential ZDC detector for EIC.

Members
Director
Hideto EN’YO
Vice Chief Scientist
Yasuyuki AKIBA
Research/Technical Scientist
Yuji GOTO (Senior Research Scientist)
Itaru NAKAGAWA (Senior Research Scientist)
Seidl RALF (Senior Research Scientist)

Yasushi WATANABE (Senior Research Scientist)
Satoshi YOKKAICHI (Senior Research Scientist)

Contract Researcher
Tomonori TAKAHASHI
Special Postdoctoral Researcher
Koki KANNO
Research Associate
Wataru NAKAIInternational Program Associates
Minho KIM (Korea Univ.)

Benard MULILO (Korea Univ.)

Senior Visiting Scientist
Toshiaki SHIBATA (Nihon Univ.)
Visiting Scientists
Kazuya AOKI (KEK)Se Young HAN (Korea Univ.)
Shoichi HASEGAWA (JAEA)
Takashi KONDO (Tokyo Metropolitan Industrial Tech. Res.
Inst.)
Shunzo KUMANO (KEK)
Tsutomu MIBE (KEK)
Yuhei MORINO (KEK)
Student Trainees
Sakiko ASHIKAGA (Kyoto Univ.)
Ryohei FUJII (Kyoto Univ.)
Kaede KAMANO (Nara Women’s Univ.)
Takehito KONDO (Hiroshima Univ.)
Yoko MINATO (Nara Women’s Univ.)

Ken-ichi NAKANO (Tokyo Tech)
Megumi NARUKI (Kyoto Univ.)
Kyoichiro OZAWA (KEK)
Susumu SATO (JAEA)
Kenta SHIGAKI (Hiroshima Univ.)
Maya SHIMOMURA (Nara Women’s Univ.)
Kiyoshi TANIDA (JAEA)

Seiya MIYATA (Univ. of Tokyo)
Tomoki MURAKAMI (Univ. of Tokyo)
Satomi NAKASUGA (Kyoto Univ.)
Junsang PARK (Seoul Nat’l Univ.)
Kenta SATO (Nagoya Univ.)- 363 -

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Ayaka SUZUKI (Nara Women’s Univ.)
Kazuki SUZUKI (Kyoto Univ.)

Yosuke UEDA (Hiroshima Univ.)
Jaehee YOO (Korea Univ.)

InternAyaka SUZUKI (Nara Women’s Univ.)
AssistantKeiko SUZUKI

List of Publications & Presentations
Publications[Original papers]
C. Aidala et al. (PHENIX Collaboration), “Measurements of µ µ pairs from open heavy flavor and Drell-Yan in p + p collisions at√
sNN = 200 GeV,” Phys. Rev. D 99, 072003 (2019).
C. Aidala et al. (PHENIX Collaboration), “Nonperturbative-transverse-momentum broadening in dihadron angular correlations in√
sNN = 200 GeV proton-nucleus collisions,” Phys. Rev. C 99, 044912 (2019).
A. Adare et al. (PHENIX Collaboration), “Measurement of two-particle correlations with respect to second- and third-order event planes√in Au + Au collisions at sNN = 200 GeV,” Phys. Rev. C 99, 054903 (2019).
C. Aidala et al. (PHENIX Collaboration), “Measurement of charm and bottom production from semileptonic hadron decays in p + p√
collisions at sNN = 200 GeV,” Phys. Rev. D 99, 092003 (2019).
A. Adare et al. (PHENIX Collaboration), “Beam energy and centrality dependence of direct-photon emission from ultra-relativistic
heavy-ion collisions,” Phys. Rev. Lett. 123, 022301 (2019).
C. Aidala et al. (PHENIX Collaboration), “Nuclear dependence of the transverse single-spin asymmetry in the production of charged√
hadrons at forward rapidity in polarized p + p, p + Al, and p + Au collisions at sNN = 200 GeV,” Phys. Rev. Lett. 123, 122001 (2019).
√
U. A. Acharya et al. (PHENIX Collaboration), “J/Ψ and Ψ (2S) production at forward rapidity in p + p collisions at sNN = 510 GeV,”
Phys. Rev. D 101, 052006 (2020).
C. Aidala et al. (PHENIX Collaboration), “Nuclear-modification factor of charged hadrons at forward and backward rapidity in p + Al√
and p + Au collisions at sNN = 200 GeV,” Phys. Rev. C 101, 034910 (2020).
C. A. Aidala, Y. Goto, et al., “The SeaQuest spectrometer at fermilab,” Nucl. Instrum. Methods Phys. Res. A 930, 49–63 (2019).
M. H. Kim, Y. Goto, I. Nakagawa, √J. S. Park, R. Seidl, et al., “Transverse single-spin asymmetry for very forward neutral pion productionin polarized p + p collisions at s = 510 GeV,” Phys. Rev. Lett. 124, 252501 (2019).
M. Ichikawa et al., “Trigger merging module for the J-PARC E16 experiment,” IEEE Trans. Nucl. Sci. 66, 2022 (2019).

[Proceedings]
A. Dote, Y. Goto, A. Hosaka, S. Kumano, and A. Monnai, “Proceedings, 8th international conference on quarks and nuclear physics(QNP2018),” JPS Conf. Proc. 26 (2019).
A. Chen, Y. Goto, et al., “Probing nucleon’s spin structures with polarized Drell-Yan in the fermilab SpinQuest experiment,” PoS
SPIN2018, 164 (2019).
Y. Itow, Y. Goto, I. Nakagawa, R. Seidl, J. S. Park, M. H. Kim, et al., “Recent results from the LHCf and RHICf experiments,” EPJ Web
Conf. 208, 05004 (2019).
0
M. H. Kim, Y. Goto, I. Nakagawa, R. Seidl, J. S. Park,√ M. H. Kim, et al., “Transverse single spin asymmetry for very forward π
production in polarized proton-proton collisions at s = 510 GeV,” EPJ Web Conf. 208, 05007 (2019).
Y. Goto, “Asymmetry measurement of very forward neutral particle production in the RHICf experiment,” Acta Phys. Polon. B Proc.
Suppl. 12, 837 (2019).
S. Ashikaga et al., (J-PARC E16 Collaboration), “Measurement of vector meson mass in nuclear matter at J-PARC,” JPS Conf. Proc. 26,
024005 (2019).

Presentations[International conferences/workshops]
Y. Goto (invited), “Nucleon structure study at RHIC and EIC,” YKIS2018b Symposium on Recent Developments in Quark-Hadron
Sciences, Kyoto, Japan, June 12, 2018.
Y. Goto (invited), “Asymmetry measurement of very forward neutral particle production in the RHICf experiment,” Diﬀraction and Low-x
2018, Reggio Calabria, Italy, August 29, 2018.
Y. Goto (oral), “Very forward neutral particle measurement in the RHICf experiment,” 5th Joint Meeting of the APS Division of Nuclear
Physics and the Physics Society of Japan, Hawaii, USA, October 26, 2018.
Y. Goto (invite), “Electron-ion collider project,” Workshop on Progress on Hadron Structure Functions in 2018, Tsukuba, Japan, November 19, 2018.
Y. Goto (invited), “Forward spin physics at PHENIX and sPHENIX,” International Workshop on Forward Physics and Forward Calorimeter Upgrade in ALICE, Tsukuba, Japan, March 7, 2019.
Y. Goto (invited), “RHICf results,” Cold QCD Workshop, RHIC & AGS Annual Users’ Meeting, Upton, New York, USA, June 4, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Y. Goto (invited), “Plan for EIC (Electron-Ion Collider),” 14th ANPhA Board meeting and Symposium in Korea, Jeju Island, Korea, June
28, 2019.
Y. Goto (invited), “Overview of future facilities for nucleon spin studies,” 11th Circum-Pan-Pacific Symposium on High Energy Spin
Physics (Pacific Spin 2019), Miyazaki, Japan, August 30, 2019.
Y. Goto (invited), “Physics and detector requirements at zero degree of EIC,” Workshop on Forward Physics and QCD at the LHC, thefuture Electron Ion Collider and Cosmic Ray Physics, Guanajuato, Mexico, November 19, 2019.
S. Yokkaichi (invited), “Measurement of the spectral change of vector mesons in nuclei at the high-momentum beam line in J-PARC
HEF,” J-PARC Symposium 2019, Tsukuba, Japan, September 23–26, 2019.
S. Ashikaga, “Measurement of vector meson mass in nuclear matter at J-PARC,” The 8th International Conference on Quarks and Nuclear
Physics (QNP2018), Tsukuba, Japan, November 13–17, 2018.
M. Ichikawa, “Trigger merging module for the J-PARC E16 experiment,” 21st IEEE Real Time ConferenceRT2018 (RT2018), Williamsburg, VA, USA, June 12, 2018.

[Domestic conferences/workshops]‫ޙ‬౻༤ೋʢট଴ߨԋʣ, ʮElectron-Ion Collider (EIC) ‫ܭ‬ըʯ, ೔ຊֶज़ձٞެ։γϯϙδ΢Ϝʮૉཻࢠ෺ཧɾ‫֩ࢠݪ‬෺ཧ෼໺ͷେ‫ܕ‬ࢪઃ‫ܭ‬ըɾେ‫ن‬໛‫ܭڀݚ‬ըϚελʔϓϥϯʯ, ౦‫ژ‬, 2019 ೥ 2 ݄ 19 ೔.
‫ޙ‬౻༤ೋ (ট଴ߨԋʣ, “Progress on RHIC-spin physics,” Progress on QCD and Nucleon Structure in 2019, ͭ͘͹, 2019 ೥ 2 ݄ 28 ೔.
‫ޙ‬౻༤ೋ (‫ޱ‬಄ൃදʣ, ʮPHENIX ࣮‫Ͱݧ‬ͷภ‫ۃ‬ཅࢠ + ‫֩ࢠݪ‬িಥʹΑΔ࠷৽ͷ݁Ռʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ,ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17 ೔.
ଜ্ஐ‫ޱ( ل‬಄ൃදʣ, ʮJ-PARC E16 ࣮‫͚ͨ޲ʹݧ‬ඈ੻‫ݕ‬ग़‫ث‬ͷ։ൃ͓ΑͼੑೳධՁʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶҏ౎Ωϟϯύε, ෱Ԭ, 2019 ೥ 3 ݄ 14–17 ೔.
࢛೔ࢢ‫ ޛ‬ʢট଴ߨԋʣ, ʮ‫֩ࢠݪ‬தͰͷϕΫτϧதؒࢠͷ࣭ྔมԽͷଌఆʯ, ELPH ‫ڀݚ‬ձ C023ʮ‫֩ࢠݪ‬தʹ͓͚Δϋυϩϯͷੑ࣭ͱΧΠϥϧରশੑͷ໾ׂʯ, ౦๺େֶిࢠޫཧֶ‫ڀݚ‬ηϯλʔ, ઋ୆, 2018 ೥ 9 ݄ 11–12 ೔.

Press releasesʮཅࢠিಥ͔Βͷࠨӈඇରশੑͳ pi தؒࢠͷੜ੒ʯ, ཧԽֶ‫ॴڀݚ‬, ౦‫ژ‬େֶӉ஦ઢ‫ॴڀݚ‬, ໊‫ݹ‬԰େֶ, ೔ຊ‫ڀݚྗࢠݪ‬։ൃ‫ߏػ‬,2020 ೥ 6 ݄ 23 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
Meson Science Laboratory
1. Abstract
Particles like muons, pions, and kaons have finite life times, so they do not exist in natural nuclei or matters. By implanting theseparticles into nuclei/matters, exotic phenomena in various objects can be studied from new point of view.
For example, kaon is the second lightest meson, which has strange quark as a constituent quark. It is expected that if one embeds
mesons into nuclei, the sizes of the nuclei become smaller and one can form a high-density object beyond the normal nuclear density.
Study of this object could lead to better understanding of the origin of the mass of the matter, and may reveal the quark degree of
freedom beyond the quark-confinement. The other example is the weak interaction in nuclear matter. It can only be studied by the
weak decay of hypernuclei, which have Lambda particle in the nuclei.
Muon provides even wider scope of studies, covering condensed matter physics as well as nuclear and atomic physics, and weare trying to extend the application field further into chemical and biological studies. For instance, stopping positively charged muonin a material, we obtain information on the magnetic properties or the local field at the muon trapped site (µSR). Injecting negatively
charged muon to hydrogen gas, muonic hydrogen atom (µp) is formed. We are planning to measure µp hyperfine splitting energy tomeasure proton magnetic radius, which is complementary quantity to the proton charge radius and its puzzle. We are also interested
in precision measurement of muon property itself, such as muon anomalous magnetic moment (g − 2).
In our research, we introduce diﬀerent kind of impurities into nuclei/matters, and study new states of matter, new phenomena, or
the object properties.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Study of meson property and interaction in nuclei
Origin of matter mass/quark degree of freedom in nuclei
Condensed matter and material studies with muon
Nuclear and particle physics studies via muonic hydrogen
Development of ultra cold muon beam, and its application from material science to particle physics

3. Summary of Research Activity(1) Hadron physics at J-PARC, RIKEN-RIBF, GSI and SPring-8
Kaon and pion will shed a new insight to the nuclear physics. The recent discovery of deeply bound pionic atom enables us toinvestigate the properties of mesons in nuclear matter. At RIKEN-RIBF, we are preparing precise experimental study of the pionicatom. Very lately, we succeeded to discover kaonic nuclear bound state, “K-pp,” at J-PARC. The yield dependence on momentumtransfer shows that observed system is unexpectedly small. We extended our study on Λ(1405) that could be K − p bound state. By
these experiments, we are studying the K̄N interaction, and clarify the nature of kaon in nuclei. At Spring-8 and at GSI, we areplanning to study omega and η′ nuclei. By these experiments, we aim to be a world-leading scientific research group using these lightmeta-stable particles.
(1-1) Deeply bound kaonic nuclei
J-PARC E15 experiment had been performed to explore the simplest kaonic nuclear bound state, “K − pp”. Because of the strong
attraction between K̄N, the K̄ in nuclei may attract surrounding nucleons, resulting in forming a deeply bound and extremely dense
object. Measurement of the kaon properties at such a high-density medium will provide precious information on the origin of hadron
masses, if the standard scenario of the hadron-mass-generation mechanism, in which the hadron masses are depends on matter densityand energy, is correct. Namely, one may study the chiral symmetry breaking of the universe and its partial restoration in nuclear
medium.
The E15 experiment was completed to observe the “K − pp” bound state by the in-flight 3 He(K − , n) reaction, which allows us
the formation via the invariant-mass spectroscopy by detecting decay particles from “K − pp”. For the experiment, we constructed a
dedicated spectrometer system at the secondary beam-line, K1.8BR, in the hadron hall of J-PARC.
With the Λpn final states obtained in the first stage experiment, we observed a kinematic anomaly in the Λp invariant mass
near the mass threshold of M(K − pp) (total mass of kaon and two protons) at the lower momentum transfer q region. We conducteda successive experiment to examine the nature of the observed kinematical anomaly in the Λpn final state, and we confirmed theexistence of the bound state below the mass threshold of M(K − pp) at as deep as the binding energy of 40 MeV. The momentum
transfer q naturally prefers lower momentum for the bound state formation, but the observed event concentration extended having theform-factor parameter ∼400 MeV/c. Based on the PWIA calculation, the data indicated that the “K − pp” system could be as small as∼0.6 fm. It is astonishingly compact in contrast to the mean nucleon distance ∼1.8 fm.
This observed signal shows that a meson ( q̄q) forms a quantum state where baryons (qqq) exist as nuclear medium, i.e., a highly
excited novel form of nucleus with a kaon, in which the mesonic degree-of-freedom still holds. This is totally new form of nuclear
system, which never been observed before.
(1-2) Precision X-ray measurement of kaonic atom
To study the K̄N interaction at zero energy from the atomic state level shift and width of kaon, we have performed an X-ray
spectroscopy of atomic 3d → 2p transition of negatively charged K-mesons captured by helium atoms. However, our first experimentis insuﬃcient in energy resolution to see the K − -nucleus potential. Aiming to provide a breakthrough from atomic level observation,- 366 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

we introduce a novel X-ray detector, namely superconducting transition-edge-sensor (TES) microcalorimeter oﬀering unprecedented
high energy resolution, being more than one order of magnitude better than that achieved in the past experiments using conventional
semiconductor detectors. The experiment J-PARC E62 aims to determine 2p-level strong interaction shifts of kaonic 3 He and 4 He
atoms by measuring the atomic 3d → 2p transition X-rays using TES detector with 240 pixels having about 23 mm2 eﬀective area
and the average energy resolution of 7 eV (FWHM) at 6 keV. We carried out the experiment at J-PARC in June 2018 and successfully
observed distinct X-ray peaks from both atoms. The data analysis is now ongoing.
Another important X-ray measurement of kaonic atom would be 2p → 1 s transition of kaonic deuteron (K − -d). We havemeasured same transition of kaonic hydrogen (K − -p), but the width and shift from electro-magnetic (EM) value reflect only isospin
average of the Kbar N interaction. We can resolve isospin dependence of the strong interaction by the measurements both for K − -p andK − -d. The experiment J-PARC E57 aims at pioneering measurement of the X-rays from K − -d atoms. Prior to full (stage-2) approvalof the E57 proposal, we performed a pilot run with hydrogen target in March 2019.
(1-3) Deeply bound pionic atoms and η′ mesonic nuclei
We have been working on precision spectroscopy of pionic atoms systematically, which leads to understanding of the non-trivial
structure of the vacuum and the origin of hadron masses. The precision data set stringent constraints on the chiral condensate at
nuclear medium. We are presently preparing for the precision systematic measurements at RIBF. A pilot experiment performed in2010 showed a unprecedented results of pionic atom formation spectra with finite reaction angles. The measurement of pionic 121 Sn
performed in 2014 showed a very good performance of the system. We have been analyzing the data to achieve information on thepion-nucleus interaction based on the pionic atom spectroscopy.
We are also working on spectroscopy of η′ mesonic nuclei in GSI/FAIR. Theoretically, peculiarly large mass of η′ is attributed
to UA(1) symmetry and chiral symmetry breaking. As a result, large binding energy is expected for η′ meson bound states in nuclei(η′ -mesonic nuclei). From the measurement, we can access information about gluon dynamics in the vacuum via the binding energy
and decay width of η′ -nuclear bound state.
(1-4) 3 Λ H lifetime puzzle and our approach
Three recent heavy ion experiments (HypHI, STAR, and ALICE) announced surprisingly short lifetime for 3 Λ H hyper-nucleus’s
Mesonic Weak Decay (MWD), which seems to be inconsistent with the fact that the 3 Λ H is a very loosely bound system. It is very
interesting to study this with a diﬀerent experimental approach. We proposed a direct measurement of 3 Λ H MWD lifetime with ∼20%
resolution at J-PARC hadron facility by using K − meson beam at 1 GeV/c. As for the feasibility test, we also measure 4 Λ H lifetime.
A Cylindrical Detector System (CDS) used in J-PARC E15/E31 experiment is employed to capture the delayed π− as a weak
decay product from 3, 4 Λ H; a calorimeter is installed in the very forward region to tag fast π0 meson emission at ∼0 degree, which
ensures that the Λ hyperon production with small recoil momentum. By this selection, we can improve the ratio between 3, 4 Λ H andquasi-free Λ and Σ background. A test beam for feasibility study with 4 He target has been conditionally approved by J-PARC PAC.
We will conduct the experiment and to present the data in short.
(2) Muon science at RIKEN-RAL branch
The research area ranges over particle physics, condensed matter studies, chemistry and life science. Our core activities are
based on the RIKEN-RAL Muon Facility located at the Rutherford-Appleton Laboratory (UK), which provides intense pulsed-muonbeams. We have variety of important research activities such as particle/nuclear physics studies with muon’s spin and condensed
matter physics by muon spin rotation/relaxation/resonance (µSR).
(2-1) Condensed matter/materials studies with µSR
To improve our two µSR spectrometers, ARGUS (Port-2) and CHRNUS (Port-4), we adjusted the threshold level of the muondetector system for the zero-field condition. At this condition, we optimized the eﬃciency of the detector system and the counting rate
was improved nearly 50% without any deformation of the time spectrum.
Among our scientific activities on µSR studies from year 2016 to 2019, following studies are most important subjects of materialsciences at the RIKEN-RAL muon facility:(1) Deformed nodal superconducting gap state and asymmetric spin-fluctuation mediated Cooper pair in the quasi twodimensional organic superconductor Λ-[BETS]2 GaCl4(2) Multi magnetic transitions in the Ru-based pyrochlore systems, R2 Ru2 O7 .
(3) Magnetic properties of the nano-cluster gold in the border of macro- and micro- scale.
(4) Novel magnetic and superconducting properties of nano-size La-based high-TC superconducting curates.
(5) Determination of muon positions estimated from density functional theory (DFT) and dipole-field calculations.
(6) Chemical muonic states in DNA molecules.
(2-2) Nuclear and particle physics studies via ultra-cold muon beam and muonic atoms
If we can improve muon beam emittance, timing and energy dispersion (so-called “ultra-cold muon”), then the capability of µSR
studies will be drastically improved. The ultra-cold muon beam can stop in a thin foil, multi-layered materials and artificial lattices, so
one can apply the µSR techniques to surface and interface science. The development of ultra-cold muon beam is also very importantas the source of pencil-like small emittance muon beam for muon g-2 measurement.
Ultra-cold muon beam has been produced by laser ionization of muoniums in vacuum (bound system of µ+ and electron). We
are developing two key components, high eﬃciency muonium generator at room temperature and high intensity ionization laser. The
study of muonium generator has been done in collaboration with TRIUMF. In 2013, we demonstrated at least 10 times increase of
the muonium emission eﬃciency by fabricating fine laser drill-holes on the surface of silica aerogel. Further study was done in 2017with more than 20 aerogel target having diﬀerent surface conditions. We are analyzing the data to identify which condition most- 367 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

contributed to increasing the muonium emission eﬃciency. We also developed a high power Lyman-α laser in collaboration with lasergroup at RIKEN. In this laser development, we succeeded to synthesize novel laser crystal Nd:YGAG, which has an ideal wavelength
property for laser amplification to generate Lyman-α by four-wave mixing in Kr gas cell. We already achieved 10 times increase of
Lyman-α generation than before. However, in order to increase the intensity by one more order, we need a larger size crystal. So far
we have inhomogeneity problem but we are trying to solve this problem.
Concerning the muonic atom, we are planning a new precise measurement of proton radius. A large discrepancy was foundrecently in the proton charge radius between the new precise value from muonic hydrogen atom at PSI and those from normal hydrogen spectroscopy and e-p scattering. We propose a precise measurement of Zemach radius (with charge and magnetic distributions
combined) using the laser spectroscopy of hyperfine splitting energy in the muonic hydrogen atom. As a key parameter for designing
the experiment, we need the quench rate of the muonic proton polarization due to collision with surrounding protons, for which only
theoretical estimations are available. We successfully measured the quench rate of muonic deuterium polarization in deuterium gas,
which confirmed the long lifetime consistent with the calculation. In this fiscal year, we carried out measurement on muonic proton in
low pressure hydrogen gas.

Members
Director
Masahiko IWASAKI
Research Scientists
Kenta ITAHASHI (Senior Research Scientist)
Yue MA (Senior Research Scientist)
Haruhiko OUTA (Senior Research Scientist)

Fuminori SAKUMA (Senior Research Scientist)
Isao WATANABE (Senior Research Scientist)

Contract Researcher
Katsuhiko ISHIDA
Junior Research Associates
Julia ANGEL (Hokkaido Univ.)
Shun SEO (Univ. of Tokyo)

Muhamad UMAR (Hokkaido Univ.)

International Program Associates
Muhammad H.B. CHE LAH (Univ. Sains Malaysia)
Redo Muhammad RAMADHAN (Univ. Indonesia)
Harison B. ROZAK (Univ. Sains Malaysia)

Suci WINARSIH (Univ. Indonesia)
Utami WIDYAISWARI (Univ. Indonesia)

Research Consultant
Masayasu KAMIMURA
Senior Visiting Scientists
Hiroyuki NOUMI (Osaka Univ.)

Kazuhiro TANAKA (KEK)

Visiting Scientists
Tadashi ADACHI (Sophia Univ.)
Hiroko ARIGA (Hokkaido Univ.)
Retno ASIH (Inst. Teknologi Sepuluh Nopember)
Fahmi ASTUTI (Inst. Teknologi Sepuluh Nopember)
KwangYong CHOI (Chung-Ang Univ.)
Catalina Oana CURCEANU (INFN)
Zyun EZAWA (Tohoku Univ.)
Hiroyuki FUJIOKA (Tokyo Tech)
Takayuki GOTO (Sophia Univ.)
Maryam HASSANVAND (Isfahan Univ. of Tech.)
Wataru HIGEMOTO (JAEA)
Ko-ichi HIRAKI (Fukushima Medical Univ.)
Satoru HIRENZAKI (Nara Women’s Univ.)
Koichi ICHIMURA (Hokkaido Univ.)
Yasuyuki ISHII (Shibaura Inst. of Tech.)
Ryosuke KADONO (KEK)
Takayuki KAWAMATA (Tohoku Univ.)
Seiko KAWAMURA (JAEA)
Takuya KOBAYASHI (Saitama Univ.)
Yoji KOIKE (Tohoku Univ.)

Seungwon LEE (Univ. of Toyama)
Kenji MATSUDA (Univ. of Toyama)
Mototsugu MIHARA (Osaka Univ.)
Yasuhiro MIYAKE (KEK)
Mohamed Ismail MOHAMED-IBRAHIM (Univ. Sains
Malaysia)
Takehito NAKANO (Ibaraki Univ.)
Takahiro NAMIKI (Univ. of Toyama)
Katsuhiko NISHIMURA (Univ. of Toyama)
Yasuo NOZUE (Osaka Univ.)
Agustinus NUGROHO (Inst. Teknologi Bandung)
Kazuki OHISHI (Comprehensive Res. Org. for Sci. and Soc.)
Yu OISHI (KEK)
Atsushi OKAZAWA (Univ. of Tokyo)
Amba D. PANT (Ibaraki Univ.)
Dita PUSPITA SARI (Shibaura Inst. of Tech.)Irwan RAMLI (Univ. Cokroaminoto Palopo)
Yuta SADA (Osaka Univ.)
Lusi SAFRIANI (Univ. Padjadjaran)
Naohito SAITO (KEK)- 368 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Ichiro SHIRAKI (Univ. of Yamanashi)
Shukri SULAIMAN (Univ. Sains Malaysia)
Ken SUZUKI (Stefan Meyer Inst.)
Kensuke SUZUKI (Tohoku Univ.)
Takao SUZUKI (Shibaura Inst. of Tech.)Tomohiro TAKAYAMA (Max Planck Inst.)
Yoshiki TANAKA (GSI)
Hiroshi TANIDA (Toyama Prefectural Univ.)

Andrea VACCHI (INFN)
Eberhard WIDMANN (Stefan Meyer Inst.)
Zhuan XU (Zhejiang Univ.)
Ichihiro YAMAUCHI (Saga Univ.)
Toshimitsu YAMAZAKI (Univ. of Tokyo)
Masaru YOSOI (Osaka Univ.)
Xu-Guang ZHENG (Saga Univ.)
Johann ZMESKAL (Austrian Academy of Sci.)

Student Trainees
Irwan RAMLI (Hokkaido Univ.)
Shu AIKAWA (Tokyo Tech)

Tanawat SAWASDEE (Suranaree Univ. of Tech.)Part-time Worker
Mayumi YOSHIMURA (Administrative Part-time Worker II)
Assistants
Yoko FUJITA
Kumiko TAKAHASHI

Mitsue YAMAMOTO

List of Publications & Presentations
Publications[Original papers]
M. Clemenza, et al., “Muonic atom X-ray spectroscopy for non-destructive analysis of archaological samples,” Journal of Radioanalyticaland Nuclear Chemistry 322, 1357–1363 (2019).
B. V. Hampshire, K. Butcher, K. Ishida, G. Green, D. Paul, and A. Hillier, “Using negative muons as a probe for depth profiling silver
Roman coinage,” Heritage 2, 400–407 (2019).
S. Asano, K. M. Suzuki, K. Kudo, I. Watanabe, A. Koda, R. Kadono, T. Noji, Y. Koike, T. Taniguchi, S. Kitagawa, K. Ishida, and M. Fujita,“Oxidation annealing eﬀects on the spin-glass-like magnetism and appearance of superconductivity in T*-type La1−x/2 Eu1−x/2 Sr x CuO4
(0.14 ≦ x ≦ 0.28),” J. Phys. Soc. Jpn. 88, 084709/1-6 (2019).
F. Astuti, M. Miyajima, T. Fukuda, M. Kodani, T. Nakano, T. Kambe, and I. Watanab, “Anionogenic magnetism combined with latticesymmetry in alkali-metal superoxide RbO2 ,” J. Phys. Soc. Jpn. 88, 043701/1-5 (2019).
M. A. Baqiya, T. Adachi, A. Takahashi, T. Konno, T. Ohgi, I. Watanabe, and Y. Koike, “Muon-spin relaxation study of the spin correlationsin the overdoped regime of electron-doped high-T C cuprate superconductors,” Phys. Rev. B 100, 064514/1-5 (2019).
S. Wenner, C. Marioara, K. Nishimura, K. Matsuda, S. Lee, T. Namiki, I. Watanabe, T. Matsuzaki, and R. Holmestad, “Muon spin
relaxation study of solute-vacancy interactions during natural aging of Al-Mg-Si-Cu alloys,” Metallurgical and Materials Transactions
A 50, 3446–3451 (2019).
T. Suzuki, K. Katayama, I. Watanabe, and H. Tanaka, “Spin-fluctuating ground state in the spin-1/2 kagome lattice (Rb1−x Cs x )2 Cu3 SnF12
with x = 0.53 observed by muon spin relaxation,” J. Phys. Soc. Jpn. 89, 074701 (2020).
K. M. Suzuki, S. Asano, H. Okabe, A. Koda, R. Kadono, I. Watanabe, and M. Fujita, “Successive magnetic ordering sequence observed
from muon spin rotation in T’-structured R2 CuO4 (R = Nd, Eu),” Phys. Rev. B (in press).
H. Yamauchi, D. P. Sari, I. Watanabe, Y. Yasui, L. -J. Chang, K. Kondo, T. U. Ito, M. Ishikado, M. Hagihara, M. D. Frontzek, S. Chi,
J. A. Fernandez-Baca, J. S. Lord, A. Berlie, A. Kotani, S. Mori, and S. Shamoto, “High-temperature short-range order in Mn3 RhSi,”
Commun. Mater. (in press).
K. Oinuma, N. Okano, H. Tsunakawa, S. Michimura, T. Kobayashi, H. Taniguchi, K. Satoh, J. Angel, I. Watanabe, Y. Ishii, H. Okamoto,and T. Itou, “Spin structure at zero magnetic field and field-induced spin reorientation transitions in a layered organic canted antiferromagnet bordered on a superconducting phase,” Phys. Rev. B (in press).
M. Fujita, K. M. Suzuki, S. Asano, H. Okabe, A. Koda, R. Kadono, and I. Watanabe, “New aspects of magnetism in T’-type Eu2 CuO2
revealed by precise muon spin rotation/relaxation measurements,” Phys. Rev. B (in press).

[Review articles]
H. Ohnishi, F. Sakuma, and T. Takahashi, “Hadron physics at J-PARC,” Prog. Part. Nucl. Phys., (in press)[Books]‫࡚ؠ‬խ඙, ࠤ‫࢙ؒٱ‬య, ࢁզ୓າ, ʮ࠷ۙͷ‫͔ڀݚ‬ΒɿK தؒࢠͱཅࢠ 2 ͔ͭΒͳΔ “‫֩ࢠݪ ”ͳົح‬ʯ, ೔ຊ෺ཧֶձࢽ, 2020 ೥ 1
݄߸ ୈ 75 ‫ר‬ୈ 1 ߸ʢ௨‫ ר‬855 ߸ʣpp. 10–15.

[Proceedings]
S. Kawasaki et al., “Λ(1405) spectroscopy via the in-flight d(K − , n) reaction at the J-PARC K1.8BR,” JPS Conf. Proc. 26, 022009 (2019).
T. Yamaga et al., “Results of KbarNN search via the (K − , n) reaction at J-PARC,” JPS Conf. Proc. 26, 023008 (2019).
T. Hashimoto et al., “Kaonic atom experiments at J-PARC,” JPS Conf. Proc. 26, 023013 (2019).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

H. Asano et al., “Spectroscopic study of the Λ(1405) resonance via the d(K − , n) reaction at J-PARC,” AIP Conf. Proc. 2130, 040018(2019).
Y. K. Tanaka et al., “Spectroscopy of η′ -mesic nuclei with WASA at GSI/FAIR,” Acta Phys. Polon. B 51, 39 (2020).

Presentations[International conferences/workshops]
F. Sakuma (invited), “K − pp bound system at J-PARC,” The 15th International Conference on Meson-Nucleon Physics and the Structureof the Nucleon (MENU-2019), Cohon University Center, Carnegie Mellon University, Pittsburgh Pennsylvania, June 2–7, 2019.
K. Itahashi (invited), “Mesons in nuclei: review and perspectives,” 3rd Jagiellonian Symposium on Fundamental and Applied Subatomic
Physics, Krakow, June 23–28, 2019.
K. Itahashi (oral), “Precision spectroscopy of pionic atoms at RIBF,” The 27th International Nuclear Physics Conference (INPC 2019),
Glasgow, UK, July 29–August 2, 2019.
T. Yamaga (oral), “Result of KbarNN search via exclusive measurements of (K − , n) reaction at J-PARC,” The 27th International Nuclear
Physics Conference (INPC 2019), Glasgow, UK, July 29–August 2, 2019.
S. Okada (oral), “Kaonic atom X-ray spectroscopy with superconducting detector,” The 27th International Nuclear Physics Conference(INPC 2019), Glasgow, UK, July 29–August 2, 2019.
T. Hashimoto (oral), “Towards the X-ray measurement of kaonic deuterium at J-PARC,” The 27th International Nuclear Physics Conference (INPC 2019), Glasgow, UK, July 29–August 2, 2019.
K. Ishida, “Status of the g − 2 and EDM experiment at J-PARC,” FCCP2019, Anacapri, Italy, August 2019.
K. Ishida, “Measurement of the proton Zemach radius from the hyperfine splitting in muonic hydrogen utilizing muon spin repolarization
with laser: Principle and Method,” Proton Radius 2019, Veli Losinji, Croatia, September 2019.
S. Kanda, “Measurement of the proton Zemach radius from the hyperfine splitting in muonic hydrogen utilizing muon spin repolarization
with laser: Preparation Status,” Proton Radius 2019, Veli Losinji, Croatia, September 2019.
K. Ishida, “Status of the g − 2 and EDM experiment at J-PARC,” Proton Radius 2019, Veli Losinji, Croatia, September 2019.
M. Iwasaki (invited), “Kaonic nuclear bound state “K − pp” observation and possible future plan,” The 3rd J-PARC symposium (JPARC2019), Tsukuba, September 23–26, 2019.
K. Ishida et al., “Laser spectroscopy of the 1s hyperfine splitting energy of muonic hydrogen for the determination of proton Zemachradius,” The 3rd J-PARC symposium (J-PARC2019), Tsukuba, Japan, September 23–26, 2019.
M. Iwasaki (invited), “A novel and peculiar quantum system—K-meson and two protons bound state,” STRANEX: Recent progress andperspectives in STRANge EXotic atoms studies and related topics ECT*, Trento, October 21–25, 2019.
F. Sakuma (invited), “Λ(1405)pn Final State in the K − + 3 He reaction,” STRANEX: Recent progress and perspectives in STRANge
EXotic atoms studies and related topics ECT*, Trento, October 21–25, 2019.

[Domestic conferences/workshops]‫࡚ؠ‬խ඙ʢট଴ߨԋʣ, ʮK தؒࢠ ͱ̎ͭͷཅࢠ͕ଋറͨ͠‫ࢠྔͳົح‬ଟମ‫ܥ‬ʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2009 ೥ 9݄ 17–20 ೔.
O. Zhadyraʢ‫ޱ‬಄ൃදʣ, ʮThe physics E31 experiment to search the Λ(1405) via the d(K − , πΣ) reaction at J-PARC K1.8BRʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2009 ೥ 9 ݄ 17–20 ೔.
ࢁզ୓າʢট଴ߨԋʣ, ʮ൓ K தؒࢠϏʔϜΛ༻͍ͨ൓ K தؒࢠ‫֩ࢠݪ‬ͷ‫ڀݚ‬ʯ, ELPH ‫ڀݚ‬ձ C024ʮϋυϩϯߏ଄ʹ͓͚Δଟཻ
ࢠ૬ؔʯ, ౦๺େֶిࢠޫཧֶ‫ڀݚ‬ηϯλʔ, ઋ୆, 2019 ೥ 10 ݄ 16–17 ೔.
ؔ԰ྋฏ, ʮGSI ʹ͓͚Δ WASA ‫ݕ‬ग़‫ث‬Λ༻͍ͨϋΠύʔ֩෼ޫ࣮‫͓ݧ‬Αͼ η′ தؒࢠ‫ݧ࣮ࡧ୳֩ࢠݪ‬ͷͨΊͷϓϥενοΫγϯ
νϨʔλόϨϧͷ։ൃʢII)ʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2009 ೥ 9 ݄ 17–20 ೔.
ੴాউ඙, ʮӳࠃཧ‫ ݚ‬RAL ϛϡΦϯࢪઃͱϛϡΦϯར༻෼ੳʯ, ୈ 2 ճจཧ༥߹γϯϙδ΢Ϝ ྔࢠϏʔϜͰྺ࢙Λ୳Δ—Ճ଎‫ث‬͕๰͙จཧ༥߹ͷ஍ฏ—, େࡕ, 2019 ೥ 12 ݄.
দຊᠳଡ (‫ޱ‬಄ൃද), ʮߴਫ਼౓ύΠதؒࢠ‫ࢠݪ‬෼ޫ࣮‫ݧ‬ͷͨΊͷࡾ໘ަସ MWDC ͷ։ൃʯ, ೔ຊ෺ཧֶձ೥࣍େձ, 2020 ೥ 3 ݄.

[Seminars]
RIKEN Symposium, “International Workshop of Topological Quantum Materials,” Tainan, Taiwan, January 10–12, 2019.
RIKEN Symposium, “The 5th International Symposium in Current Progress in Mathematics and Sciences,” Depok, Indonesia, July 9–10,
2019.

AwardsS. Winarsih, RIKEN Summer School 2019, Poster Prize (in Physics).
S. Winarsih, RIKEN Summer School 2019, Poster Prize (Best Presentation).
S. Winarsih, RIKEN Exchange Meeting 2019, Poster Prize (Student Section), ཧ‫ݚ‬ӫๆ৆ ൘‫݈ڮ‬ଠ 2020 ೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
RIKEN BNL Research Center
1. Abstract
The RIKEN BNL Research Center was established in April 1997 at Brookhaven National Laboratory with Professor T. D. Lee ofColumbia University as its initial Director. It is funded by the Rikagaku Kenkyusho (RIKEN, The Institute of Physical and Chemical
Research) of Japan. The Center is dedicated to the study of strong interactions, including spin physics, lattice QCD and RHIC
physics through the nurturing of a new generation of young physicists. Professor Lee was succeeded by BNL Distinguished Scientist,
N. P. Samios, who served until 2013. Dr. S. H. Aronson led the Center from 2013. After strong and significant leadership for 4 years,
S. Aronson stepped down from Director in March 31st 2017. Hideto En’yo succeeds from JFY 2017. Support for RBRC was initiallyfor five years and has been renewed four times, and presently extends to 2023. The Center is located in the BNL Physics Department.
The RBRC Theory Group activities are closely and intimately related to those of the Nuclear Theory, High Energy Theory, andLattice Gauge Theory Groups at BNL. The RBRC Experimental Group works closely with Radiation Laboratory at RIKEN, Wako,
the RHIC Spin Group at BNL, the RHIC Spin Physics community, and the PHENIX/sPHENIX collaboration. BNL provides oﬃce
space, management, and administrative support. In addition, the Computational Science Initiative (CSI) and Information Technology
Division (ITD) at BNL provide support for computing. The Deputy Director of RBRC is D. Morrison (BNL). D. Kharzeev (Stony
Brook/BNL) is leader of the Theory Group. Y. Akiba (RIKEN) is Experimental Group leader. T. Izubuchi (BNL) is Computing Group
leader.

2. Major Research Subjects
Major research subjects of the theory group are(1) Heavy Ion Collision(2) Perturbative QCD(3) Phenomenological QCD
Major research subjects of the computing group are(1) Search for new law of physics through tests for Standard Model of particle and nuclear physics(2) Dynamics of QCD and related theories(3) Theoretical and algorithmic development for lattice field theories, QCD machine design
Major research subject of the experimental group are(1) Experimental Studies of the Spin Structure of the Nucleon(2) Study of Quark-Gluon Plasma at RHIC
(3) sPHENIX detector construction

3. Summary of Research Activity
Summary of Research Activities of the three groups of the Center are given in the sections of each group.

Members
Director
Hideto EN’YO
Deputy Director
David P. MORRISON
Administrative Staﬀ
Kazushige FUKUSHIMA (Administration Manager, Nishina
Center and iTHEMS Promotion Oﬃce)
Hiroshi ITO (Deputy Administration Manager, Nishina Centerand iTHEMS Promotion Oﬃce)- 371 -

Pamela ESPOSITO (Administrative Assistant)
Maureen MCNEIL-SHEA (Administrative Assistant)

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
RIKEN BNL Research Center
Theory Group
1. Abstract
The eﬀorts of the RBRC theory group are concentrated on the major topics of interest in High Energy Nuclear Physics andstrongly interacting Chiral Matter. This includes: understanding of the Quark-Gluon Plasma; the nature of dense quark matter; theinitial state in high energy collisions, the Color Glass Condensate; its evolution through a Glasma; spin physics, as is relevant forpolarized hadronic collisions; physics relevant to electron-hadron collisions and the Electron-Ion Collider; quantum transport and the
Chiral Magnetic Eﬀect.
Theory Group hosted many joint tenure track positions with universities in U.S. and Japan.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Heavy Ion Collisions
Perturbative Quantum Chromo-Dynamics (QCD)
Phenomenological QCD
Chiral Matter

3. Summary of Research Activity(1) Phase diagram of QCD
The heavy ion program at Relativistic Heavy Ion Collider (RHIC) at BNL is focused on the study of the properties of QCD matterat high energy densities and high temperatures. The RBRC Theory group performs research that supports and guides the experimental
program at RHIC. In the past year, RBRC researchers had developed the theory of bulk viscosity’s behavior near the critical point andinvestigated universality-driven analytic structure of QCD crossover (V. Skokov).
Y. Kikuchi (in collaboration with K. Kashiwa and A. Tomiya) have developed a novel approach to the phase transitions using theneural network. In collaboration with R. Kobayashi, K. Shiozaki, and S. Ryu), Y. Kikuchi has proven a new theorem with higher-form
symmetry and applied it to the quantum dimer models.
(2) QCD Matter at High Energy Density and at small x
The RHIC experimental heavy ion program is designed to study the properties of matter at energy densities much greater thanthat of atomic nuclei. This includes the initial state of nucleus-nucleus collisions, the Color Glass Condensate, the intermediate state
to which it evolves, the Glasma, and lastly the thermal state to which it evolves, the Quark-Gluon Plasma. Theorists at the RBRC havemade important contributions to all of these subjects.
During the past year, D. Kharzeev and V. Skokov in their papers investigated the role of entanglement in gluon fields at small
Bjorken x in generating the azimuthal anisotropy of hadrons produced in AA and pA collisions at RHIC. It has been found that thesmall x gluon distributions are directly related to the entanglement entropy. D. Kharzeev, in collaboration with T. Ullrich and Z. Tu,
investigated the role of entanglement in explaining the LHC data on hadron multiplicity distributions, and proposed a program to study
entanglement at the EIC.
Y. Hatta has investigated the photoproduction of J/Ψ charmonium near the threshold and its link to the problem of the origin of
the proton’s mass. He has found that this process can be used to extract the proton mass distribution. Y. Hatta has also developed
the theory of spin dependence of Pomeron and Odderon in elastic scattering, and proposed a mechanism for single spin asymmetry
observed at RHIC. He has also made important contributions to developing the science program at the EIC.
Y. Mehtar-Tani has developed a theory of jet propagation through a dense QCD matter that properly takes into account the multiple
scattering eﬀects. He has also evaluated higher order QCD corrections to jet quenching, and proposed a dynamical grooming algorithm
for QCD jets.
C. Shen has advanced the applications of hydrodynamics to the description of heavy ion collisions, and built a quantitative modelfor the Beam Energy Scan at RHIC. In collaboration with Kharzeev and others, he has implemented the eﬀects of magnetic field on
the hydrodynamical evolution.
The activity of RBRC members described above bridges the gap between fundamental theory and phenomenology of heavy
ion collisions. This includes the lattice QCD studies, the analytical work on the dynamics of phase transitions, the development ofhydrodynamical and kinetic theory approaches incorporating quantum anomalies, and phenomenology. Much of the current work in
the field is based on the ideas originally developed by the RBRC theorists.
(3) Chiral Matter
Much of the work done at the RBRC Theory group has broad implications beyond the domain of Nuclear and High Energy
physics. One example is the Chiral Magnetic Eﬀect, originally proposed to occur in quark-gluon plasma, but discovered recently incondensed matter systems, so-called Dirac and Weyl semimetals (the original experimental observation of CME was made at BNL in
ZrTe5 in a paper co-authored by D. Kharzeev). It has become clear that RBRC can make a very substantial impact also on condensed
matter physics, where the methods developed at RBRC can be applied to a new set of problems. Vice versa, some of the new theoreticaldevelopments in condensed matter physics can be utilized for the study of QCD matter. Because of this, the RBRC developed a new- 372 -

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initiative on Chiral Matter focusing on the studies of quantum behavior in strongly interacting matter containing chiral fermions – thisincludes the quark-gluon plasma, electroweak plasma, Dirac and Weyl semimetals, and topological insulators.
In the past year, the RBRC members within this new initiative obtained a number of new results. Some of them, with a direct
relevance for the quark-gluon plasma, have been already described above; other results are of direct relevance for condensed matterphysics. D. Kharzeev and his students have proposed a new chiral magnetic photocurrent that has been observed experimentally.
Kharzeev in collaboration with Q. Li have developed a concept of a new type of “chiral qubit” based on Dirac and Weyl semimetals.
The Chiral Matter initiative has already broadened the impact of RBRC beyond the traditional domain of high-energy nuclear
physics, and has extended the RBRC research into a new and extremely active area.

Members
Group Leader
Dmitri KHARZEEV
Deputy Group Leaders
Yoshitaka HATTARBRC Researchers
Jordy DE VRIES
Yuta KIKUCHI
Yacine MEHTAR-TANI

Chun SHEN
Vladimir SKOKOV

Visiting Scientists
Hiromichi NISHIMURA (Keio Univ.)

Yuya TANIZAKI (North Carolina State Univ.)

List of Publications & Presentations
Publications[Original papers]
D. E. Kharzeev and Y. Kikuchi, “Real-time chiral dynamics from a digital quantum simulation,” Phys. Rev. Res. 2, 023342 (2020)
doi:10.1103/PhysRevResearch.2.023342 [arXiv:2001.00698 [hep-ph]].
S. Kaushik, D. E. Kharzeev, and E. J. Philip, “Transverse chiral magnetic photocurrent induced by linearly polarized light in symmetric
weyl semimetals,” [arXiv:2006.04857 [cond-mat.mes-hall]].
J. Garaud, M. N. Chernodub, and D. E. Kharzeev, “Vortices with magnetic field inversion in non-centrosymmetric superconductors,”[arXiv:2003.10917 [cond-mat.supr-con]].
U. Gürsoy, D. Kharzeev, E. Marcus, K. Rajagopal, and C. Shen, “Charge-dependent flow induced by electromagnetic fields in heavy ion
collisions,” [arXiv:2002.12818 [hep-ph]].
A. S. Gorsky and D. E. Kharzeev, “Tensor supercurrent in QCD,” Phys. Rev. D 101, 114002 (2020) doi:10.1103/PhysRevD.101.114002[arXiv:2001.07638 [hep-th]].
K. Hao, D. Kharzeev, and V. Korepin, “Bethe Ansatz for XXX chain with negative spin,” Int. J. Mod. Phys. A 34, 1950197 (2019)
doi:10.1142/S0217751X19501975 [arXiv:1909.00800 [hep-th]].
G. Inghirami, M. Mace, Y. Hirono, L. Del Zanna, D. E. Kharzeev, and M. Bleicher, “Magnetic fields in heavy ion collisions: flow andcharge transport,” Eur. Phys. J. C 80, 293 (2020) doi:10.1140/epjc/s10052-020-7847-4 [arXiv:1908.07605 [hep-ph]].
M. Chernodub, J. Garaud, and D. Kharzeev, [arXiv:1908.00392 [cond-mat.supr-con]].
D. Kharzeev, E. Shuryak, and I. Zahed, “Baryogenesis and helical magnetogenesis from the electroweak transition of the minimal Standard
Model,” [arXiv:1906.04080 [hep-ph]].
Z. Tu, D. E. Kharzeev, and T. Ullrich, “Einstein-podolsky-rosen paradox and quantum entanglement at subnucleonic scales,” Phys. Rev.
Lett. 124, 062001 (2020) doi:10.1103/PhysRevLett.124.062001 [arXiv:1904.11974 [hep-ph]].
X. G. Huang, D. E. Kharzeev, and H. Taya, “Real-time dynamics of axion particle production due to spontaneous decay of a coherent
axion field,” Phys. Rev. D 101, 016011 (2020) doi:10.1103/PhysRevD.101.016011 [arXiv:1904.08184 [hep-ph]].
D. Kharzeev and J. Liao, Nucl. Phys. News 29, 26–31 (2019) doi:10.1080/10619127.2018.1495479
D. E. Kharzeev and Q. Li, “The chiral qubit: quantum computing with chiral anomaly,” [arXiv:1903.07133 [quant-ph]].
S. Kaushik, D. E. Kharzeev, and E. J. Philip, “Chiral magnetic photocurrent in dirac and weyl materials,” Phys. Rev. B 99, 075150 (2019)
doi:10.1103/PhysRevB.99.075150 [arXiv:1810.02399 [cond-mat.mes-hall]].
Y. Hatta, “J/Ψ photo-production near threshold and the proton mass problem,” doi:10.1142/9789811214950 0035
Y. Hatta and Y. Zhao, “Parton distribution function for the gluon condensate,” [arXiv:2006.02798 [hep-ph]].
R. Boussarie and Y. Hatta, “QCD analysis of near-threshold quarkonium leptoproduction at large photon virtualities,” Phys. Rev. D 101,
114004 (2020) doi:10.1103/PhysRevD.101.114004 [arXiv:2004.12715 [hep-ph]].
Y. Hatta, “How EIC can help us to understand heavy-ion collisions,” [arXiv:2004.05336 [hep-ph]].
Y. Hagiwara, Y. Hatta, R. Pasechnik, and J. Zhou, “Spin-dependent Pomeron and Odderon in elastic proton-proton scattering,” Eur. Phys.
J. C 80, 427 (2020) doi:10.1140/epjc/s10052-020-8007-6 [arXiv:2003.03680 [hep-ph]].

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C. A. Aidala, E. Aschenauer, F. Aslan, A. Bacchetta, I. Balitsky, S. Benic, S. Bhattacharya, M. Boglione, M. Burkardt, J. Cammarota,
G. A. Chirilli, C. Cocuzza, A. Courtoy, D. de Florian, P. Di Nezza, A. Dumitru, S. Fucini, K. Fukushima, Y. Furletova, L. Gamberg,
O. Garcia-Montero, F. Gelis, V. Guzey, Y. Hatta, F. Hautmann, T. J. Hobbs, T. Horn, E. Iancu, S. Joosten, Z. B. Kang, R. Kishore,
Y. V. Kovchegov, P. Kroll, K. Kumerički, K. Kutak, T. Lappi, H. W. Lin, X. Liu, S. Liuti, C. Lorcé, H. Mäntysaari, C. Marquet,
Y. Makris, K. A. Mamo, Y. Mehtar-Tani, A. Metz, Z. E. Meziani, G. A. Miller, J. Miller, A. Mukherjee, P. M. Nadolsky, F. I. Olness,
B. Pasquini, B. Pire, C. Pisano, D. Pitonyak, M. V. Polyakov, A. Prokudin, J. W. Qiu, M. Radici, A. Rajan, S. Rajesh, M. Rinaldi,
K. Roy, C. Royon, N. Sato, M. Schlegel, G. Schnell, P. Schweitzer, S. Scopetta, R. Seidl, K. Semenov-Tian-Shansky, A. Signori,
D. Sokhan, A. M. Stasto, L. Szymanowski, A. Tarasov, D. Triantafyllopoulos, T. Ullrich, R. Venugopalan, I. Vitev, W. Vogelsang,
A. Vossen, B. T. Wang, S. Wallon, K. Watanabe, C. Weiss, B. W. Xiao, H. U. Yee, and Y. Zhao, “Probing nucleons and nuclei in highenergy collisions,” doi:10.1142/11684 [arXiv:2002.12333 [hep-ph]].
R. Boussarie, Y. Hatta, L. Szymanowski, and S. Wallon, “Probing the Sivers function with an unpolarized target: GTMD distributions
and the Odderons,” Phys. Rev. Lett. 124, 172501 (2020) doi:10.1103/PhysRevLett.124.172501 [arXiv:1912.08182 [hep-ph]].
Y. Hatta, M. Strikman, J. Xu, and F. Yuan, “Sub-threshold J/Ψ and Υ production in γA collisions,” Phys. Lett. B 803, 135321 (2020)
doi:10.1016/j.physletb.2020.135321 [arXiv:1911.11706 [hep-ph]].
S. Benic, Y. Hatta, H. N. Li, and D. J. Yang, “Single-spin asymmetries at two loops,” Phys. Rev. D 100, 094027 (2019)
doi:10.1103/PhysRevD.100.094027 [arXiv:1909.10684 [hep-ph]].
Y. Hatta, N. Mueller, T. Ueda, and F. Yuan, Phys. Lett. B 802, 135211 (2020) doi:10.1016/j.physletb.2020.135211 [arXiv:1907.09491[hep-ph]].
Y. Hatta and X. Yao, “QCD evolution of the orbital angular momentum of quarks and gluons: Genuine twist-three part,” Phys. Lett. B
798, 134941 (2019) doi:10.1016/j.physletb.2019.134941 [arXiv:1906.07744 [hep-ph]].
Y. Hatta, A. Rajan, and D. L. Yang, “Near threshold J/Ψ and Υ photoproduction at JLab and RHIC,” Phys. Rev. D 100, 014032 (2019)
doi:10.1103/PhysRevD.100.014032 [arXiv:1906.00894 [hep-ph]].
R. Boussarie, Y. Hatta, and F. Yuan, “Proton spin structure at small-x,” Phys. Lett. B 797, 134817 (2019) doi:10.1016/j.physletb.2019.134817[arXiv:1904.02693 [hep-ph]].
X. Yao, Y. Hagiwara, and Y. Hatta, “Computing the gluon Sivers function at small-x,” Phys. Lett. B 790, 361–366 (2019)
doi:10.1016/j.physletb.2019.01.029 [arXiv:1812.03959 [hep-ph]].
S. Benić and Y. Hatta, “Single spin asymmetry in forward pA collisions: Phenomenology at RHIC,” Phys. Rev. D 99, 094012 (2019)
doi:10.1103/PhysRevD.99.094012 [arXiv:1811.10589 [hep-ph]].
B. Schenke, C. Shen, and P. Tribedy, “Running the gamut of high energy nuclear collisions,” [arXiv:2005.14682 [nucl-th]].
A. Czajka, S. Hauksson, C. Shen, S. Jeon, and C. Gale, “Eﬀects of the mean field on fluid dynamics in the relaxation time approximation,”[arXiv:2004.11920 [nucl-th]].
B. Schenke, C. Shen, and D. Teaney, “Transverse momentum fluctuations and their correlation with elliptic flow in nuclear collision,”[arXiv:2004.00690 [nucl-th]].
C. Shen and S. Alzhrani, “A collision geometry-based 3D initial condition for relativistic heavy-ion collisions,” [arXiv:2003.05852 [nuclth]].
C. Gale, J. F. Paquet, B. Schenke, and C. Shen, “Probing early-time dynamics and quark-gluon plasma transport properties with photons
and hadrons,” [arXiv:2002.05191 [hep-ph]].
J. F. Paquet et al. [JETSCAPE], “Revisiting Bayesian constraints on the transport coeﬃcients of QCD,” [arXiv:2002.05337 [nucl-th]].
A. Monnai, B. Schenke, and C. Shen, “QCD equation of state at finite densities for nuclear collisions,” [arXiv:2002.02661 [nucl-th]].
C. Shen, “Studying QGP with flow: A theory overview,” [arXiv:2001.11858 [nucl-th]].
B. Schenke, C. Shen, and P. Tribedy, “Bulk properties and multi-particle correlations in large and small systems,” [arXiv:2001.09949[nucl-th]].
Y. Tachibana, C. Shen, and A. Majumder, “Bulk medium evolution has considerable eﬀects on jet observables!,” [arXiv:2001.08321[nucl-th]].
A. Kumar, A. Majumder, and C. Shen, “Energy and scale dependence of q̂ and the “JET puzzle”,” Phys. Rev. C 101, 034908 (2020)
doi:10.1103/PhysRevC.101.034908 [arXiv:1909.03178 [nucl-th]].
B. Schenke, C. Shen, and P. Tribedy, “Hybrid Color Glass Condensate and hydrodynamic description of the Relativistic Heavy Ion
Collider small system scan,” Phys. Lett. B 803, 135322 (2020) doi:10.1016/j.physletb.2020.135322 [arXiv:1908.06212 [nucl-th]].
G. Vujanovic, J. F. Paquet, C. Shen, G. S. Denicol, S. Jeon, C. Gale, and U. Heinz, “Exploring the influence of bulk viscosity of QCD on
dilepton tomography,” Phys. Rev. C 101, 044904 (2020) doi:10.1103/PhysRevC.101.044904 [arXiv:1903.05078 [nucl-th]].
A. Monnai, B. Schenke, and C. Shen, “Equation of state at finite densities for QCD matter in nuclear collisions,” Phys. Rev. C 100, 024907(2019) doi:10.1103/PhysRevC.100.024907 [arXiv:1902.05095 [nucl-th]].
A. Majumder, S. Cao, C. Shen, and G. Y. Qin, “Eﬀects of drag induced radiation and multi-stage evolution on heavy quark energy loss,”
PoS HardProbes2018, 130 (2019) doi:10.22323/1.345.0130 [arXiv:1902.02217 [nucl-th]].
C. Gale, S. Jeon, S. Mcdonald, J. F. Paquet, and C. Shen, “Centrality dependence of the direct photonmultiplicity in heavy ion collisions,”
PoS HardProbes2018, 178 (2019) doi:10.22323/1.345.0178 [arXiv:1901.07019 [nucl-th]].
B. Schenke, C. Shen, and P. Tribedy, “Multi-particle and charge-dependent azimuthal correlations in heavy-ion collisions at the Relativistic
Heavy-Ion Collider,” Phys. Rev. C 99, 044908 (2019) doi:10.1103/PhysRevC.99.044908 [arXiv:1901.04378 [nucl-th]].
√C. Gale, S. Jeon, S. McDonald, J. F. Paquet, and C. Shen, “Photon radiation from heavy-ion collisions in the sNN = 19–200 GeV
regime,” Nucl. Phys. A 982, 767–770 (2019) doi:10.1016/j.nuclphysa.2018.08.005 [arXiv:1807.09326 [nucl-th]].

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M. Singh, C. Shen, S. McDonald, S. Jeon, and C. Gale, “Hydrodynamic fluctuations in relativistic heavy-ion collisions,” Nucl. Phys. A
982, 319–322 (2019) doi:10.1016/j.nuclphysa.2018.10.061 [arXiv:1807.05451 [nucl-th]].
C. Shen and B. Schenke, “Dynamical initialization and hydrodynamic modeling of relativistic heavy-ion collisions,” Nucl. Phys. A 982,
411–414 (2019) doi:10.1016/j.nuclphysa.2018.08.007 [arXiv:1807.05141 [nucl-th]].
B. Schenke, C. Shen, and P. Tribedy, “Features of the IP-Glasma,” Nucl. Phys. A 982, 435–438 (2019) doi:10.1016/j.nuclphysa.2018.08.015[arXiv:1807.05205 [nucl-th]].
S. Ryu, S. McDonald, C. Shen, S. Jeon, and C. Gale, “Eﬀects of hadronic rescattering in mini-jet production and energy loss at the LHC,”PoS High-pT2017, 014 (2019) doi:10.22323/1.320.0014
S. Cao, A. Majumder, G. Y. Qin, and C. Shen, “Drag induced radiation and multi-stage eﬀects in heavy-flavor energy loss,” Phys. Lett.
B 793, 433–439 (2019) doi:10.1016/j.physletb.2019.05.020 [arXiv:1711.09053 [nucl-th]].
B. Chakraborty, M. Honda, T. Izubuchi, Y. Kikuchi, and A. Tomiya, “Digital quantum simulation of the Schwinger model with topologicalterm via adiabatic state preparation,” [arXiv:2001.00485 [hep-lat]].
K. Kashiwa, Y. Kikuchi, and A. Tomiya, “Phase transition encoded in neural network,” PTEP 2019, 083A04 (2019)
doi:10.1093/ptep/ptz082 [arXiv:1812.01522 [cond-mat.dis-nn]].
R. Kobayashi, K. Shiozaki, Y. Kikuchi, and S. Ryu, “Lieb-Schultz-Mattis type theorem with higher-form symmetry and the quantum
dimer models,” Phys. Rev. B 99, 014402 (2019) doi:10.1103/PhysRevB.99.014402 [arXiv:1805.05367 [cond-mat.stat-mech]].
W. Dekens, J. de Vries, K. Fuyuto, E. Mereghetti, and G. Zhou, “Sterile neutrinos and neutrinoless double beta decay in eﬀective field
theory,” J. High Energy Phys. 06, 097 (2020) doi:10.1007/JHEP06(2020)097 [arXiv:2002.07182 [hep-ph]].
J. de Vries, E. Epelbaum, L. Girlanda, A. Gnech, E. Mereghetti, and M. Viviani, “Parity- and time-reversal-violating nuclear forces,”[arXiv:2001.09050 [nucl-th]].
V. Cirigliano, W. Dekens, J. De Vries, M. Graesser, E. Mereghetti, S. Pastore, M. Piarulli, U. Van Kolck, and R. Wiringa, “Renormalized
approach to neutrinoless double- β decay,” Phys. Rev. C 100, 055504 (2019) doi:10.1103/PhysRevC.100.055504 [arXiv:1907.11254[nucl-th]].
J. de Vries, G. Falcioni, F. Herzog, and B. Ruijl, “Two- and three-loop anomalous dimensions of Weinberg’s dimension-six CP-odd
gluonic operator,” [arXiv:1907.04923 [hep-ph]].
V. Cirigliano, A. Crivellin, W. Dekens, J. de Vries, M. Hoferichter, and E. Mereghetti, “CP violation in higgs-gauge interactions: fromtabletop experiments to the LHC,” Phys. Rev. Lett. 123, 051801 (2019) doi:10.1103/PhysRevLett.123.051801 [arXiv:1903.03625 [hepph]].
F. Oosterhof, B. Long, J. de Vries, R. Timmermans, and U. van Kolck, Phys. Rev. Lett. 122, 172501 (2019) doi:10.1103/
PhysRevLett.122.172501 [arXiv:1902.05342 [hep-ph]].
J. Dragos, T. Luu, A. Shindler, J. de Vries, and A. Yousif, “Confirming the existence of the strong CP problem in lattice QCD with thegradient flow,” [arXiv:1902.03254 [hep-lat]].
J. De Vries, M. Postma, and J. van de Vis, “The role of leptons in electroweak baryogenesis,” J. High Energy Phys. 04, 024 (2019)
doi:10.1007/JHEP04(2019)024 [arXiv:1811.11104 [hep-ph]].
J. Kim, J. Dragos, A. Shindler, T. Luu, and J. de Vries, “Towards a determination of the nucleon EDM from the quark chromo-EDM
operator with the gradient flow,” PoS LATTICE2018, 260 (2019) doi:10.22323/1.334.0260 [arXiv:1810.10301 [hep-lat]].
J. de Vries, P. Draper, K. Fuyuto, J. Kozaczuk, and D. Sutherland, “Indirect signs of the peccei-quinn mechanism,” Phys. Rev. D 99,
015042 (2019) doi:10.1103/PhysRevD.99.015042 [arXiv:1809.10143 [hep-ph]].
W. Dekens, J. de Vries, M. Jung, and K. Vos, “The phenomenology of electric dipole moments in models of scalar leptoquarks,” J. HighEnergy Phys. 01, 069 (2019) doi:10.1007/JHEP01(2019)069 [arXiv:1809.09114 [hep-ph]].
J. Dragos, T. Luu, A. Shindler, J. de Vries, and A. Yousif, “Improvements to nucleon matrix elements within a θ vacuum from Lattice
QCD,” PoS LATTICE2018, 259 (2019) doi:10.22323/1.334.0259 [arXiv:1809.03487 [hep-lat]].
A. Connelly, G. Johnson, F. Rennecke, and V. Skokov, “Universal location of the Yang-Lee edge singularity in O(N) theories,”[arXiv:2006.12541 [cond-mat.stat-mech]].
A. Connelly, G. Johnson, S. Mukherjee, and V. Skokov, “Universality driven analytic structure of QCD crossover: radius of convergenceand QCD critical point,” [arXiv:2004.05095 [hep-ph]].
C. P. Korthals Altes, H. Nishimura, R. D. Pisarski, and V. V. Skokov, “Free energy of a holonomous plasma,” Phys. Rev. D 101, 094025(2020) doi:10.1103/PhysRevD.101.094025 [arXiv:2002.00968 [hep-ph]].
A. Dumitru, V. Skokov, and T. Stebel, “Subfemtometer scale color charge correlations in the proton,” Phys. Rev. D 101, 054004 (2020)
doi:10.1103/PhysRevD.101.054004 [arXiv:2001.04516 [hep-ph]].
H. Duan, C. Akkaya, A. Kovner, and V. V. Skokov, “Entanglement, partial set of measurements, and diagonality of the density matrix inthe parton model,” Phys. Rev. D 101, 036017 (2020) doi:10.1103/PhysRevD.101.036017 [arXiv:2001.01726 [hep-ph]].
C. P. Korthals Altes, H. Nishimura, R. D. Pisarski, and V. V. Skokov, “Conundrum for the free energy of a holonomous gluonic plasma at
cubic order,” Phys. Lett. B 803, 135336 (2020) doi:10.1016/j.physletb.2020.135336 [arXiv:1911.10209 [hep-th]].
S. Schlichting and V. Skokov, “Saturation corrections to dilute-dense particle production and azimuthal correlations in the Color Glass
Condensate,” Phys. Lett. B 806, 135511 (2020) doi:10.1016/j.physletb.2020.135511 [arXiv:1910.12496 [hep-ph]].
S. Mukherjee and V. Skokov, “Universality driven analytic structure of QCD crossover: radius of convergence in baryon chemical potential,” [arXiv:1909.04639 [hep-ph]].
V. Skokov, “Measuring the Weizsäcker-Williams distribution of linearly polarized gluons at an electron-ion collider through dijet azimuthal asymmetries,” PoS DIS2019, 256 (2019) doi:10.22323/1.352.0256 [arXiv:1907.10334 [hep-ph]].

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M. Martinez, T. Schäfer, and V. Skokov, “Critical behavior of the bulk viscosity in QCD,” Phys. Rev. D 100, 074017 (2019)
doi:10.1103/PhysRevD.100.074017 [arXiv:1906.11306 [hep-ph]].
R. D. Pisarski, V. V. Skokov, and A. Tsvelik, “A Pedagogical Introduction to the Lifshitz Regime,” Universe 5, 48 (2019)
doi:10.3390/universe5020048
M. Mace, V. V. Skokov, P. Tribedy, and R. Venugopalan, “Initial state description of azimuthally collimated long range correlations inultrarelativistic light-heavy ion collisions,” [arXiv:1901.10506 [hep-ph]].
N. Armesto, F. Dominguez, A. Kovner, M. Lublinsky, and V. Skokov, “The Color Glass Condensate density matrix: Lindblad evolution,
entanglement entropy and Wigner functional,” J. High Energy Phys. 05, 025 (2019) doi:10.1007/JHEP05(2019)025 [arXiv:1901.08080[hep-ph]].
H. Nishimura, C. Korthals-Altes, R. D. Pisarski, and V. Skokov, “Thermal eﬀective potential for the Polyakov loop to higher loop order,”PoS Confinement2018, 155 (2019) doi:10.22323/1.336.0155 [arXiv:1811.11736 [hep-th]].
A. Dumitru, V. Skokov, and T. Ullrich, “Measuring the Weizsäcker-Williams distribution of linearly polarized gluons at an electron-ion
collider through dijet azimuthal asymmetries,” Phys. Rev. C 99, 015204 (2019) doi:10.1103/PhysRevC.99.015204 [arXiv:1809.02615[hep-ph]].
K. Dusling, M. Mace, V. V. Skokov, P. Tribedy, and R. Venugopalan, “Multiparticle correlations and collectivity in small systems fromthe initial state,” Nucl. Phys. A 982, 495–498 (2019) doi:10.1016/j.nuclphysa.2018.09.051 [arXiv:1807.06032 [hep-ph]].
M. Mace, V. V. Skokov, P. Tribedy, and R. Venugopalan, “Systematics of azimuthal anisotropy harmonics in proton–nucleus collisions at
the LHC from the Color Glass Condensate,” Phys. Lett. B 788, 161–165 (2019) doi:10.1016/j.physletb.2018.09.064 [arXiv:1807.00825[hep-ph]].
M. Mace, V. V. Skokov, P. Tribedy, and R. Venugopalan, “Hierarchy of azimuthal anisotropy harmonics in collisions of small systems fromthe Color Glass Condensate,” Phys. Rev. Lett. 121, 052301 (2018) doi:10.1103/PhysRevLett.121.052301 [arXiv:1805.09342 [hep-ph]].
R. D. Pisarski, V. V. Skokov, and A. M. Tsvelik, “Fluctuations in cool quark matter and the phase diagram of Quantum Chromodynamics,”
Phys. Rev. D 99, 074025 (2019) doi:10.1103/PhysRevD.99.074025 [arXiv:1801.08156 [hep-ph]].
A. Dumitru, F. Gelis, T. Lappi, and Y. Mehtar-Tani, “Summary of week VII,” doi:10.1142/9789811214950 0057
Y. Mehtar-Tani, A. Soto-Ontoso, and K. Tywoniuk, “Tagging boosted hadronic objects with dynamical grooming,” [arXiv:2005.07584[hep-ph]].
J. Barata and Y. Mehtar-Tani, “Improved opacity expansion at NNLO for medium induced gluon radiation,” [arXiv:2004.02323 [hep-ph]].
Y. Mehtar-Tani, “Improved opacity expansion for medium-induced parton splitting,” [arXiv:2003.02884 [hep-ph]].
C. A. Aidala, E. Aschenauer, F. Aslan, A. Bacchetta, I. Balitsky, S. Benic, S. Bhattacharya, M. Boglione, M. Burkardt, J. Cammarota,
G. A. Chirilli, C. Cocuzza, A. Courtoy, D. de Florian, P. Di Nezza, A. Dumitru, S. Fucini, K. Fukushima, Y. Furletova, L. Gamberg,
O. Garcia-Montero, F. Gelis, V. Guzey, Y. Hatta, F. Hautmann, T. J. Hobbs, T. Horn, E. Iancu, S. Joosten, Z. B. Kang, R. Kishore,
Y. V. Kovchegov, P. Kroll, K. Kumerički, K. Kutak, T. Lappi, H. W. Lin, X. Liu, S. Liuti, C. Lorcé, H. Mäntysaari, C. Marquet,
Y. Makris, K. A. Mamo, Y. Mehtar-Tani, A. Metz, Z. E. Meziani, G. A. Miller, J. Miller, A. Mukherjee, P. M. Nadolsky, F. I. Olness,
B. Pasquini, B. Pire, C. Pisano, D. Pitonyak, M. V. Polyakov, A. Prokudin, J. W. Qiu, M. Radici, A. Rajan, S. Rajesh, M. Rinaldi,
K. Roy, C. Royon, N. Sato, M. Schlegel, G. Schnell, P. Schweitzer, S. Scopetta, R. Seidl, K. Semenov-Tian-Shansky, A. Signori,
D. Sokhan, A. M. Stasto, L. Szymanowski, A. Tarasov, D. Triantafyllopoulos, T. Ullrich, R. Venugopalan, I. Vitev, W. Vogelsang,
A. Vossen, B. T. Wang, S. Wallon, K. Watanabe, C. Weiss, B. W. Xiao, H. U. Yee, and Y. Zhao, “Probing nucleons and nuclei in highenergy collisions,” doi:10.1142/11684 [arXiv:2002.12333 [hep-ph]].
R. Boussarie and Y. Mehtar-Tani, “On gauge invariance of transverse momentum dependent distributions at small x,” [arXiv:2001.06449[hep-ph]].
Y. Mehtar-Tani, A. Soto-Ontoso, and K. Tywoniuk, “Dynamical grooming of QCD jets,” Phys. Rev. D 101, 034004 (2020) doi:10.1103/
PhysRevD.101.034004 [arXiv:1911.00375 [hep-ph]].
Y. Mehtar-Tani and K. Tywoniuk, “Improved opacity expansion for medium-induced parton splitting,” [arXiv:1910.02032 [hep-ph]].
Y. Mehtar-Tani, A. Soto-Ontoso, and M. Verweij, “Background estimator for jet studies in p + p and A + A collisions,” Phys. Rev. D 100,
114023 (2019) doi:10.1103/PhysRevD.100.114023 [arXiv:1904.12815 [hep-ph]].
Y. Mehtar-Tani, “Gluon bremsstrahlung in finite media beyond multiple soft scattering approximation,” J. High Energy Phys. 07, 057(2019) doi:10.1007/JHEP07(2019)057 [arXiv:1903.00506 [hep-ph]].
Y. Mehtar-Tani and K. Tywoniuk, “Higher-order corrections to jet quenching,” PoS HardProbes2018, 096 (2019) doi:10.22323/1.345.0096[arXiv:1903.01302 [hep-ph]].
K. Tywoniuk and Y. Mehtar-Tani, “Toward a unified description of jet and medium scales in heavy-ion collisions,” Nucl. Phys. A 982,
631–634 (2019) doi:10.1016/j.nuclphysa.2018.12.003
H. A. Andrews, L. Apolinario, R. A. Bertens, C. Bierlich, M. Cacciari, Y. Chen, Y. T. Chien, L. C. Mendez, M. Deak, D. d’Enterria,
F. Dominguez, P. C. Harris, K. Kutak, Y. J. Lee, Y. Mehtar-Tani, J. Mulligan, M. Nguyen, C. Ning-Bo, D. Perepelitsa, G. Salam,M. Spousta, J. G. Milhano, K. Tywoniuk, M. Van Leeuwen, M. Verweij, V. Vila, U. A. Wiedemann, and K. C. Zapp, “Novel tools andobservables for jet physics in heavy-ion collisions,” J. Phys. G 47, 065102 (2020) doi:10.1088/1361-6471/ab7cbc [arXiv:1808.03689[hep-ph]].

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Subnuclear System Research Division
RIKEN BNL Research Center
Experimental Group
1. Abstract

RIKEN BNL Research Center (RBRC) Experimental Group studies the strong interactions (QCD) using RHIC accelerator at
Brookhaven National Laboratory, the world first heavy ion collider and polarized p + p collider. We have three major activities: Spin
Physics at RHIC, Heavy ion physics at RHIC, and detector upgrades of PHENIX experiment at RHIC.
We study the spin structure of the proton using the polarized proton-proton collisions at RHIC. This program has been promoted
by RIKEN’s leadership. The first focus of the research is to measure the gluon spin contribution to the proton spin. Recent resultsfrom PHENIX π0 measurement and STAR jet measurement has shown that gluons in the proton carry about 30% of the proton spin.
This is a major milestone of RHIC spin program. The second goal of the spin program is to measure the polarization of anti-quarks inthe proton using W → e and W → µ decays. The results of W → e measurement was published in 2016. The final results of W → µ
was published in 2018.
The aim of Heavy ion physics at RHIC is to re-create Quark Gluon Plasma (QGP), the state of Universe just after the Big Bang.
Two important discoveries, jet quenching eﬀect and strong elliptic flows, have established that new state of dense matter is indeed
produced in heavy ion collisions at RHIC. We are now studying the property of the matter. Recently, we have measured direct photons
in Au + Au collisions for 1 < pT < 3 GeV/c, where thermal radiation from hot QGP is expected to dominate. The comparison between
the data and theory calculations indicates that the initial temperature of 300 MeV to 600 MeV is achieved. These values are well above
the transition temperature to QGP, which is calculated to be approximately 160 MeV by lattice QCD calculations.
We had major roles in detector upgrades of PHENIX experiment, namely, the silicon vertex tracker (VTX) and muon trigger
upgrades. Both of the upgrade is now complete. The VTX is the main device to measure heavy quark (charm and bottom) production
and the muon trigger is essential for W → µ measurement. The results from the first run with VTX detector in 2011 was published.
The results show that electrons from bottom quark decay is strongly suppressed at high pT , but the suppression is weaker than that ofcharm decay electron for 3 < pT < 4 GeV/c. We have recorded 10 times as much Au + Au collisions data in each of the 2014 run and2016 run. The large dataset will produce definitive results on heavy quark production at RHIC.
PHENIX completed its data taking in 2016. We are now working on R&D of intermediate silicon tracker INTT for sPHENIX, a
new experiment at RHIC that will be installed in the PHENIX IR.

2. Major Research Subjects(1) Experimental Studies of the Spin Structure of the Nucleon(2) Study of Quark-Gluon Plasma at RHIC
(3) PHENIX detector upgrades

3. Summary of Research Activity

We study the strong interactions (QCD) using the RHIC accelerator at Brookhaven National Laboratory, the world first heavy ion
collider and polarized p + p collider. We have three major activities: Spin Physics at RHIC, Heavy ion physics at RHIC, and detector
upgrades of PHENIX experiment. From 2015, Y. Akiba (Experimental Group Leader) is the Spokesperson of PHENIX experiment.
(1) Experimental study of spin structure of proton using RHIC polarized proton collider
How is the spin of proton formed with 3 quarks and gluons? This is a very fundamental question in Quantum Chromodynamics(QCD), the theory of the strong nuclear forces. The RHIC Spin Project has been established as an international collaboration between
RIKEN and Brookhaven National Laboratory (BNL) to solve this problem by colliding two polarized protons for the first time inhistory. This project also has extended the physics capabilities of RHIC.
The first goal of the Spin Physics program at RHIC is to determine the gluon contribution to proton spin. It is known that the spinof quark accounts for only 25% of proton spin. The remaining 75% should be carried either by the spin of gluons or the orbital angularmomentum of quarks and gluons. One of the main goals of the RHIC spin program has been to determine the gluon spin contribution.
Before the start of RHIC, there was little experimental constraint on the gluon polarization, ∆G.
PHENIX measures the double helicity asymmetry (ALL ) of π0 production to determine the gluon polarization. Our most recent
publication of π0 ALL measurement at 510 GeV shows non-zero value of ALL , indicating that gluons in the proton is polarized. Global
analysis shows that approximately 30% of proton spin is carried by gluons.
RHIC achieved polarized p + p collisions at 500 GeV in 2009. The collision energy increased to 510 GeV in 2012 and 2013. The
main goal of these high energy p + p run is to measure anti-quark polarization via single spin asymmetry AL of the W production. We
upgraded the muon trigger system to measure W → µ decays in the forward direction. With the measurement of W → e and W → µ,we can cover a wide kinematic range in anti-quark polarization measurement. The 2013 run is the main spin run at 510 GeV. PHENIX
has recorded more than 150/pb of data in the run. The final results of the AL measurement in W → e channel in combined data of2011 to 2013 was published in 2016. The paper on the final results of W → µ was published in 2018. These high statistics results givestrong constraints on the polarization of anti-quarks in the proton.
RHIC has the first polarized proton nucleus collision run in 2015. In this run, we discovered a surprisingly large nuclear dependence of single spin asymmetry of very forward neutron. The paper of this discovery was published in Physical Review Letters.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Fig. 1. Single spin asymmetry AL of electrons from W and Z decays. The AL is sensitive to the polarization of anti-quarks in the proton. The curves and theshaded region show theoretical calculations based on various polarized parton distribution (PDF) sets. The mid-rapidity points were published in Phys.
Rev. D 93, 051103(R) (2016). The forward/backward points were published in Phys. Rev. D 98, 032007 (2018).

Fig. 2. Single spin asymmetry AN of very forward neutron in p + p, p + Al, and p + Au collision. Published in Phys. Rev. Lett. 120, 022001 (2018).

(2) Experimental study of Quark-Gluon Plasma using RHIC heavy-ion collider
The goal of high energy heavy ion physics at RHIC is study of QCD in extreme conditions i.e. at very high temperature and atvery high energy density. Experimental results from RHIC have established that dense partonic matter is formed in Au + Au collisions
at RHIC. The matter is very dense and opaque, and it has almost no viscosity and behaves like a perfect fluid. These conclusions areprimarily based on the following two discoveries:• Strong suppression of high transverse momentum hadrons in central Au + Au collisions (jet quenching)• Strong elliptic flow
These results are summarized in PHENIX White paper, which has approximately 2700 citations to date. The focus of the research inheavy ion physics at RHIC is now to investigate the properties of the matter. RBRC have played the leading roles in some of the mostimportant results from PHENIX in the study of the matter properties. These include (1) measurements of heavy quark production
from the single electrons from heavy flavor decay (2) measurements of J/Ψ production (3) measurements of di-electron continuumand (4) measurements of direct photons.
Our most important result is the measurement of direct photons for 1 < pT < 5 GeV/c in p + p and Au + Au through their internalconversion to e+ e− pairs. If the dense partonic matter formed at RHIC is thermalized, it should emit thermal photons. Observation ofthermal photon is direct evidence of early thermalization, and we can determine the initial temperature of the matter. It is predictedthat thermal photons from QGP phase is the dominant source of direct photons for 1 < pT < 3 GeV/c at the RHIC energy. We
measured the direct photon in this pT region from measurements of quasi-real virtual photons that decays into low-mass e+ e− pairs.
Strong enhancement of direct photon yield in Au + Au over the scaled p + p data has been observed. Several hydrodynamical models
can reproduce the central Au + A data within a factor of two. These models assume formation of a hot system with initial temperatureof T init = 300 MeV to 600 MeV. This is the first measurement of initial temperature of quark gluon plasma formed at RHIC. These- 378 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Fig. 3. Left: Cover of Nature Physics March 2019 issue featuring the PEHNIX article reporting strong evidence of small QGP droplent formation. Right: Dataof elliptic and triangular flow measured in p+Au, d+Au and 3 He+Au collisions.

Fig. 4. Preliminary results of the elliptic flow strength ν2 of single electrons from charm and bottom decays.

results are recently published in Physical Review Letters. Y. Akiba is the leading person of the analysis and the main author of thepaper. He received 2011 Nishina memorial Prize mainly based on this work.
PHENIX experiment measured the flow in small collision systems (p + Au, d + Au, and 3 He + Au), and observed strong flow in allof these systems. Theoretical models that assume formation of small QGP droplets best describe the data. These results are publishedin Nature Physics in 2019.
(3) Detector upgrade
The group had major roles in several PHENIX detector upgrades, namely, the silicon vertex tracker (VTX) and muon trigger
upgrades. VTX is a high precision charged particle tracker made of 4 layers of silicon detectors. It is jointly funded by RIKEN andthe US DOE. The inner two layers are silicon pixel detectors and the outer two layers are silicon strip detectors. Y. Akiba is the project
manager and A. Deshpande is the strip system manager. The VTX detector was completed in November 2010 and subsequently
installed in PHENIX. The detector started taking data in the 2011 run. With the new detector, we measure heavy quark (charm andbottom) production in p + p, A + A collisions to study the properties of quark-gluon plasma. The final result of the 2011 run was
published. The result show that single electrons from bottom quark decay is suppressed, but not as strong as that from charm decay
in low pT region (3 < pT < 4 GeV/c). This is the first measurement of suppression of bottom decay electrons at RHIC and the firstobservation that bottom suppression is smaller than charm. We have recorded 10 times as much Au + Au collisions data in eachof the 2014 run and 2016 run. The large dataset will produce definitive results on heavy quark production at RHIC. A preliminary
results on the elliptic flow strength ν2 of b → e and c → e has been presented in Quark Matter 2018 conference. The results ofbottom/charm ratios in p + p collisions at 200 GeV from the 2015 run was published (Phys. Rev. D99 092003 (2019)). A paper
reporting measurements of the nuclear suppression factor RAA of charm and bottom in Au+Au collisions from the 2014 data is inpreparation.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Fig. 5. Three ladder telescope made from INTT silicon tracker prototype. The prototype detector was tested in a beam test at FNAL in February 2018.

PHENIX completed its data taking in 2016. We are now working on R&D of intermediate silicon tracker INTT for sPHENIX, a
new experiment at RHIC that will be installed in the PHENIX IR. A three ladder telescope of INTT prototype modules was tested ina beam test at FNAL. The prototype detector worked very well during the test.

Members
Group Leader
Yasuyuki AKIBARBRC Researchers
Jan C. BERNAUER
Megan CONNORS
Yuji GOTO
Takashi HACHIYA
Itaru NAKAGAWA
Seidl RALF

Atsushi TAKETANI
Takahito TODOROKI
Marta VERWEIJ
Yasushi WATANABE
Satoshi YOKKAICHISpecial Temporary Research Scientist
Takashi ICHIHARA
Visiting Scientists
Stefan BATHE (Baruch College Univ. of New York)
Gaku MITSUKA (KEK)
Rachid NOUICER (BNL)

Masahiro OKAMURA (BNL)
Takao SAKAGUCHI (BNL)
Takashi SAKO (Univ. of Tokyo)

Student Trainees
Kai-Yu Cheng (National Central U)
Anthony Hodges (Georgia State U)
Lihan Liu (Vanderbilt U)

Xiao Rui (Purdue U)
Cheng-Wei Shih (National Central U)
Cheuk-Ping Wong (Georgia State U)

List of Publications & Presentations
Publications[Original papers]
C. Aidala et al., “Creation of quark-gluon plasma droplets with three distinct geometries,” Nature Physics 15, 214 (2019).
A. Adare et al., “Beam energy and centrality dependence of direct-photon emission from ultrarelativistic heavy-ion collisions,” Phys. Rev.
Lett. 123, 022301 (2019).
C. Aidala et al., “Nuclear dependence of the transverse single-spin asymmetry in the production of charged hadrons at forward rapidity√
in polarized p+p, p+Al, and p+Au collisions at sNN = 200 GeV,” Phys. Rev. Lett. 123, 122001 (2019).
A. Adare et al., “Multiparticle azimuthal correlations for extracting event-by-event elliptic and triangular flow in Au+Au collisions at√
sNN = 200 GeV,” Phys. Rev. C 99, 024903 (2019).
√
C. Aidala et al., “Nonpertuarbative transverse momentum broadening in dihedron angular correlations in sNN = 200 GeV proton-nucleus
collisions,” Phys. Rev. C 99 044912 (2019).
A. Adare et al., “Measurement of two-particle correlations with respect to second- and third- order event planes in Au+Au collisions at√
sNN = 200 GeV,” Phys. Rev. C 99, 5,054903 (2019).
√
C. Aidla et al., “Measurements of µµ pairs from open heavy flavor and Drell-Yan in p+p collisions at s = 200 GeV,” Phys. Rev. D 99,
072003 (2019).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

C. Aidla et al., “Measurement of charm and bottom production from semileptonic hadron decays in p+p collisons at
Phys. Rev. D 99, 092003 (2019).

√

sNN = 200 GeV,”

Presentations[International conferences/workshops]
T. Hachiya (invited), “PHENIX heavy flavor highlights,” 8th International conference on new frontiers in physics (ICNFP 2019), Crete,
Greece, August 21–29, 2019.
M. Connors (invited), “PHENIX jighlights,” 28th International conference on ultrarelativistic nucleus-nucleus collisions (Quark Matter2019), Wuhan, China, November 4–9, 2019.
T. Todoroki (oral), “Quark flavor dependence of particle flow in nucleus-nucleus collisions measured by PHENIX,” 28th International
conference on ultrarelativistic nucleus-nucleus collisions (Quark Matter 2019), Wuhan, China, November 4–9, 2019.

AwardsMegan Connors, CAREER award from the National Science Foundation.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
RIKEN BNL Research Center
Computing Group
1. Abstract

The computing group founded in 2011 as a part of the RIKEN BNL Research Center established at Brookhaven National Laboratory in New York, USA, and dedicated to conduct researches and developments for large-scale physics computations important forparticle and nuclear physics. The group was forked from the RBRC Theory Group.
The main mission of the group is to provide important numerical information that is indispensable for theoretical interpretationof experimental data from the first principle theories of particle and nuclear physics. Their primary area of research is lattice quantum
chromodynamics (QCD), which describes the sub-atomic structures of hadrons, which allow us the ab-initio investigation for stronglyinteracting quantum field theories beyond perturbative analysis.
The RBRC group and its collaborators have emphasized the necessity and importance of precision calculations, which will precisely check the current understandings of nature, and will have a potential to find a physics beyond the current standard model offundamental physics. We have therefore adopted techniques that aim to control and reduce any systematic errors. This approach has
yielded many reliable results.
The areas of the major activities are R&D for high performance computers, developments for computing algorithms, and researches of particle, nuclear, and lattice theories. Since the inception of RBRC, many breakthroughs and pioneering works has carriedout in computational forefronts. These are the use of the domain-wall fermions, which preserve chiral symmetry, a key symmetry forunderstanding nature of particle nuclear physics, the three generations of QCD devoted supercomputers, pioneering works for QCD
calculation for Cabibbo-Kobayashi-Maskawa theory, QCD + QED simulation for isospin breaking, novel algorithm for error reduction
in general lattice calculation. Now the chiral quark simulation is performed at the physical up, down quark mass, the precision formany basic quantities reached to accuracy of sub-percent, and the group is aiming for further important and challenging calculations,such as the full and complete calculation of CP violating K → ππ decay and ε′ /ε, or hadronic contributions to muon’s anomalous
magnetic moment g − 2. Another focus area is the nucleon’s shape, structures, and the motion of quarks and gluon inside nucleon
called parton distribution, which provide theoretical guidance to physics for sPHENIX and future Electron Ion Collider (EIC), Hyper
Kamiokande, DUNE, or the origin of the current matter rich universe (rather than anti-matter). Towards finite density QCD, they also
explore Quantum Computing to overcome the sign problem.

2. Major Research Subjects(1) Search for new law of physics through tests for Standard Model of particle and nuclear physics, especially in the frameworkof the Cabibbo-Kobayashi-Maskawa (CKM), hadronic contributions to the muon’s anomalous magnetic moment (g − 2) for
FNAL and J-PARC’s experiments, as well as B physics at Belle II and LHCb.
(2) Nuclear Physics and dynamics of QCD or related theories, including study for the structures of nucleons related to physics
for Electron Ion Collider (EIC or eRHIC), Hyper Kamiokande, T2K, DUNE.
(3) Theoretical and algorithmic development for lattice field theories, QCD machine (co-)design and code optimization.

3. Summary of Research Activity

In 2011, QCD with Chiral Quarks (QCDCQ), a third-generation lattice QCD computer that is a pre-commercial version of IBM’s
Blue Gene/Q, was installed as an in-house computing resource at the RBRC. The computer was developed by collaboration among
RBRC, Columbia University, the University of Edinburgh, and IBM. Two racks of QCDCQ having a peak computing power of 2 × 200
TFLOPS are in operation at the RBRC. In addition to the RBRC machine, one rack of QCDCQ is owned by BNL for wider use forscientific computing. In 2013, 1/2 rack of Blue Gene/Q is also installed by US-wide lattice QCD collaboration, USQCD. The group
has also used the IBM Blue Gene supercomputers located at Argonne National Laboratory and BNL (NY Blue), and Hokusai and
RICC, the super computers at RIKEN (Japan), Fermi National Accelerator Laboratory, the Jeﬀerson Lab, and others. From 2016, thegroup started to use the institutional cluster both GPU and Intel Knight Landing (KNL) clusters installed at BNL and University ofTokyo extensively.
Such computing power enables the group to perform precise calculations using up, down, and strange quark flavors with proper
handling of the important symmetry, called chiral symmetry, that quarks have. The group and its collaborators carried out the first
calculation for the direct breaking of CP (Charge Parity) symmetry in the hadronic K meson decay (K → ππ) amplitudes, ε′ /ε, which
provide a new information to CKM paradigm and its beyond. They also provide the hadronic contribution in muon’s anomalous magnetic moment (g − 2)µ . These calculation for ε′ /ε, hadronic light-by-light of (g − 2), are long waited calculation in theoretical physics
delivered for the first time by the group. The K → ππ result in terms of ε′ /ε currently has a large error, and deviates from experimental
results by 2.1 σ. To collect more information to decide whether this deviation is from the unknown new physics or not, the group continues to improve the calculation in various way to reduce their error. Hadronic light-by-light contribution to (g − 2)µ is improved bymore than two order of magnitudes compared to our previous results. As of 2019 summer, their calculation is among the most precise
determination for the g − 2 hadronic vacuum polarization (HVP), and only one calculation in the world for the hadronic light-by-light(HLbL) contribution at physical point. These (g − 2)µ calculations provide the first principle theoretical prediction for on-going newexperiment at FNAL and also for the planned experiment at J-PARC. Other projects including flavor physics in the framework of the
CKM theory for kaons and B mesons that include the new calculation of b-baryon decay, Λb → p; the electromagnetic properties- 382 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

of hadrons; the proton’s and neutron’s form factors and structure function including electric dipole moments; proton decay; nucleon
form factors, which are related to the proton spin problem or neutrino-nucleon interaction; Neutron-antineutron oscillations; inclusive
hadronic decay of τ leptons; nonperturbative studies for beyond standard model such composite Higgs or dark matter models fromstrong strongly interacting gauge theories; a few-body nuclear physics and their electromagnetic properties; QCD thermodynamics
in finite temperature/density systems such as those produced in heavy-ion collisions at the Relativistic Heavy Ion Collider; Quantum
Information, Quantum Computing; and applications of machine learning in field theories.
The RBRC group and its collaborators have emphasized the necessity and importance of precision calculations, which will provide
stringent checks for the current understandings of nature, and will have a potential to find physics beyond the current standard modelof fundamental physics. We have therefore adopted techniques that aim to control and reduce any systematic errors. This approach
has yielded many reliable results, many of basic quantities are now computed within sub-percent accuracies.
The group also delivers several algorithmic breakthroughs, which speed up generic lattice gauge theory computation. These novel
technique divides the whole calculation into frequent approximated calculations, and infrequent expensive and accurate calculation
using lattice symmetries called All Mode Averaging (AMA), or a compression for memory needs by exploiting the local-coherenceof QCD dynamics. Together with another formalism, zMobius fermion, which approximate chiral lattice quark action eﬃciently, thetypical calculation is now improved by a couple of orders of magnitudes, and more than an order of magnitude less memory needs
compared to the traditional methods. RBRC group and its collaborators also provide very eﬃcient and generic code optimized to thestate-of-arts CPU or GPU, and also improve how to eﬃciently generate QCD ensemble.

Extrapolation to continuum and infinite volume (prelim)30

48I-64I
24D
32D
48D
32Dfine25aµ × 1010

c1
1−(1 − c2 a2)(m µL)2

20
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(6)

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32Dfine−2−4aµ × 1010

F2(a, L) = F2



13/20

−6
−8
−10

5

−12

0

−14
0

0.05

0.1

0.15

0.2

0

1/(mµ L)2

0.05

0.1

0.15

0.2

1/(mµ L)2

Connected diagrams

Disconnected diagrams± 0.28) × 10−10
acHLbL = (28.46 ± 3.66
adHLbL= (−12.39 ± 2.09stat ± 1.63sys,a2) × 10−10
µ

(7)
(8)

aHLbL
= (16.06 ± 3.90stat ± 1.91sys,a2) × 10−10µ(9)Fig. 1. The bottom plots are Hadronic
Light-by-Light (HLbL) contributionsstat
to muon anomalous
magnetic
moment shown at top diagram.
2
sys,a
µ

• Plenary talk given at LATTICE 2018. We are still accumulating more statistics.

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0.5
0

JAM
xFitter
FNAL
ASV

RIKEN Accel.
0 Prog. Rep. 53

0.2

0.4

0.6

Ⅵ. RNC ACTIVITIES

0.8

1

x
4
0.4

µ = 3.2 GeV

3.5

fv⇡ (x)2.5
20.3
xfv⇡ (x)

3

and
to 2
was
futu

0.2

0.1

1.5
0

0

0.2

0.4

0.8

1

x

1
continuum est.
JAM18
0.5
xFitter
FNAL
ASV
0
0
0.2

0.6

0.4

0.6

0.8

1

x

FIG. 29.
Our determinations of valence PDF of pion,⇡fv (x, µ), at factorization scale µ = 3.2 GeV. (Top panel)
The PDF determination from a = 0.04 fm data (red) andMembersa = 0.04 fm data (blue). (Bottom panel) Our estimate ofGroup Leader
PDF in the continuum limit (blue). In both top and bottom
Taku IZUBUCHI
panels, the darker inner band includes only the statistical erSpecial Postdoctoral Researchersror.
The lighter outer band includes
both statistical error as
Akio
TOMIYA
Enrico RINALDI
well as the systematic errors. Our estimates are compared
RBRC Researcherswith AOKIthe(RIKEN
FNAL
E-0615
estimate[37](greensymbols),
ASV
Yasumichi
BNL Fellow,
KEK)
SergeySYRITSYN(RHIC Physics
Fellow)
Ethan NEIL (RHIC Physics Fellow)
Luchang JIN (RHIC Physics Fellow)
estimate[27](greenStefanMEINEL (RHIC
Physics
Fellow) dashed line), JAM estimate [70] (blackband) and xFitter analysis [75] (purple line). Insets: the same
Visiting Scientists⇡
dataBLUM
are(Univ.
replotted
xf(BNL)
Thomasof Connecticut) as the traditional
Meifeng LINv (x) versus x.

Fig. 2. Parton Distribution of pion as function of momentum fraction of valence quark, x, at factorization scale 3.2 GeV compred to phenomenological andexperimental determinations. From arXiv:2007.06590

Chulwoo JUNG (BNL)
Shigemi OHTA (KEK)
Tomomi ISHIKAWA (Shanghai Jiao-Tong Univ.)
Christoph LEHNER (BNL)

Robert MAWHINNEY (Columbia Univ.)
Hiroshi OKI (Nara Women’s Univ.)
Christopher KELLY (Columbia Univ.)

Finally, we compare our PDF determinations with
384 other global fit analysis in - thesummary plot in Fig. 29.
Along with our determinations of valence PDFs at the

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

List of Publications & Presentations
Publications[Original papers]
C. Y. Seng, X. Feng, M. Gorchtein, and L. C. Jin, “Joint lattice QCD–dispersion theory analysis confirms the quark-mixing top-row
unitarity deficit,” Phys. Rev. D 101, 111301 (2020). doi:10.1103/PhysRevD.101.111301 [arXiv:2003.11264 [hep-ph]].
X. Feng, M. Gorchtein, L. C. Jin, P. X. Ma, and C. Y. Seng, “First-principles calculation of electroweak box diagrams from lattice QCD,”
Phys. Rev. Lett. 124, 192002 (2020). doi:10.1103/PhysRevLett.124.192002 [arXiv:2003.09798 [hep-lat]].
T. Blum, N. Christ, M. Hayakawa, T. Izubuchi, L. Jin, C. Jung, and C. Lehner, “Hadronic light-by-light scattering contribution to themuon anomalous magnetic moment from lattice QCD,” Phys. Rev. Lett. 124, 132002 (2020). doi:10.1103/PhysRevLett.124.132002[arXiv:1911.08123 [hep-lat]].
X. Feng, Y. Fu, and L. C. Jin, “Lattice QCD calculation of the pion charge radius using a model-independent method,” Phys. Rev. D 101,
051502 (2020). doi:10.1103/PhysRevD.101.051502 [arXiv:1911.04064 [hep-lat]].
X. Y. Tuo, X. Feng, and L. C. Jin, “Long-distance contributions to neutrinoless double beta decay π− → π+ ee,” Phys. Rev. D 100, 094511(2019). doi:10.1103/PhysRevD.100.094511 [arXiv:1909.13525 [hep-lat]].
G. Rendon, S. Meinel et al., “I = 1/2 S -wave and P-wave Kπ scattering and the κ and K ∗ resonances from lattice QCD,” arXiv:2006.14035[hep-lat]
T. Blake, S. Meinel, and D. van Dyk. “Bayesian analysis of b → sµ+ µ− Wilson coeﬃcients using the full angular distribution ofΛb → Λ(→ p π− )µ+ µ− Decays,” Phys. Rev. D 101, 035023 (2020).
R. Larsen, S. Meinel, S. Mukherjee, and P. Petreczky, “Excited bottomonia in quark-gluon plasma from lattice QCD,” Phys. Lett. B 800,
135119 (2020).
R. Larsen, S. Meinel, S. Mukherjee, and P. Petreczky, “Thermal broadening of bottomonia: Lattice nonrelativistic QCD with extended
operators,” Phys. Rev. D 100, 074506 (2019).
J. R. Green, M. Engelhardt, N. Hasan, S. Krieg, S. Meinel, J. W. Negele, A. V. Pochinsky, and S. N. Syritsyn, “Excited-state eﬀects innucleon structure on the lattice using hybrid interpolators,” Phys. Rev. D 100, 074510 (2019).
L. Leskovec, S. Meinel, M. Pflaumer, and M. Wagner, “Lattice QCD investigation of a doubly-bottom b̄b̄ud tetraquark with quantum
numbers I(J P ) = 0(1+ )” Phys. Rev. D 100, 014503 (2019).
N. Hasan, J. Green, S. Meinel, M. Engelhardt, S. Krieg, J. Negele, A. Pochinsky, and S. Syritsyn, “Nucleon axial, scalar, and tensor
charges using lattice QCD at the physical pion mass,” Phys. Rev. D 99, 114505 (2019).
T. Izubuchi, S. Syritsyn et al., “Valence parton distribution function of pion from fine lattice,” Phys. Rev. D 100, 034516 (2019).
E. Rinaldi, S. Srytsyn, et al. “Lattice QCD determination of neutron-antineutron matrix elements with physical quark masses,” Phys. Rev.
D 99, 074510 (2019).
K. -Y. Kim, M. Nishida, M. Nozaki, M. Seo, Y. Sugimoto, and A. Tomiya, “Entanglement after quantum quenches in lifshitz scalar
theories,” J. Stat. Mech. 1909, 093104 (2019) arXiv:1904.01276 [hep-lat]
B. Chakraborty, M. Honda, T. Izubuchi, Y. Kikuchi, and A. Tomiya, “Digital quantum simulation of the schwinger model with topologicalterm via adiabatic state preparation,” arXiv:2001.00485 [hep-lat][Review articles]
T. Aoyama, L. Jin, T. Blum, T. Izubuchi, C. Lehner et al., “The anomalous magnetic moment of the muon in the standard model,”arXiv:2006.04822 [hep-ph]V. Cirgliano, Z. Davoudi, T. Izubuchi et al., “The role of lattice QCD in searches for violations of fundamental symmetries and signals
for new physics,” Eur. Phys. J. A 55, 197 (2019).
P. Gambino, S. Meinel, et al., “Challenges in semileptonic B decays,” arXiv:2006.07287 [hep-ph]W. Detmold, S. Meinel, S. Syritsyn, et al. [USQCD Collaboration]. “Hadrons and nuclei,” Eur. Phys. J. A 55, 193 (2019).
C. Lehner, S. Meinel et al. [USQCD Collaboration]. “Opportunities for lattice QCD in quark and lepton flavor physics,” Eur. Phys. J. A
55, 195 (2019).
T. Izubuchi[Books]K. Hashimoto, A. Tomiya et al., “Physisits use machine learning (in Japanese),” Asakura, October 2019.
K. Hashimoto, A. Tanaka, and A. Tomiya, “Deep Learning and physics (in Japanese),” Kodansha, June 2019.

[Proceedings]
K. Maltman, T. Izubuchi, et al., “Current status of inclusive hadronic τ determinations of |Vus |,” SciPost Phys. Proc. 1, 006 (2019).
M. Kawaguchi, S. Matsuzaki, and A. Tomiya, “Analysis on nonperturbative flavor violation at chiral crossover criticality in QCD,”
arXiv:2005.07003 [hep-ph]
M. Kawaguchi, S. Matsuzaki, and A. Tomiya, “Nonperturbative flavor breaking in topological susceptibility at Hot QCD criticality,”
arXiv:2003.11375 [hep-ph]
H. -T. Ding, S. -T. Li, S. Mukherjee, A. Tomiya, and X. -D. Wang, “Meson masses in external magnetic fields with HISQ fermions,”
arXiv:2001.05322 [hep-lat]
H. -T. Ding, O. Kaczmarek, F. Karsch, S. -T. Li, S. Mukherjee, A. Tomiya, and Y. Zhang, “Dirac Eigenvalue spectrum of Nf = 2+1 QCD- 385 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

towards the chiral limit using HISQ fermions,” arXiv:2001.05217 [hep-lat]
A. Tomiya, H. -T. Ding, X. -D. Wang, Y. Zhang, S. Mukherjee, and C. Schmidt, “Phase structure of three flavor QCD in external magnetic
fields using HISQ fermions,” arXiv:1904.01276 [hep-lat]

Presentations[International conference/workshops]
L. Jink (invited), “QED corrections to hadron masses,” χ QCD collaboration meeting at University of Kentucky, December 13, 2019.
L. Jin (invited), “Status of Muon g − 2,” Brookhaven Forum 2019: Particle Physics and Cosmology in the 2020’s, September 26, 2019.
L. Jin (invited), “Hadronic Light-by-Light RBC,” Hadronic contributions to (g − 2) µ , INT Workshop INT-19-74W, September 11, 2019.
L. Jin (invited, plenary) “QED∞ in muon g − 2, hadron spectroscopy, and beyond,” 37th international conference on lattice field theory,
June 20, 2019.
A. Tomiya (invited), “Applications of machine learning to computational physics,” A.I. for nuclear physics (invited), Jeﬀerson Laboratory,
Virginia, USA, November 3, 2020.
A. Tomiya, “Chiral condensate in Schwinger model by quantum computer,” International Workshop on “Theoretical Particle Physics
2019,” Tokyo, Japan, November 4, 2019.
A. Tomiya, “Phase structure of three flavor QCD in external magnetic fields,” XQCD 2019, Tokyo, Japan, June 2019.
A. Tomiya, “Phase structure of three flavor QCD in external magnetic fields,” Lattice 2019, Wuhan, China, June 2019.

[Domestic Conferences/Workshops]
A. Tomiya, “Phase structure of three flavor QCD in external magnetic fields,” JPS meeting, Kyushu University, March 2019.
A. Tomiya, “QCD phase transition under external magnetic field with improved staggered fermions,” JPS meeting, Tokyo University of
Science, March 2018.

[Seminars]
A. Tomiya, “Lattice gauge theory with quantum computers,” (Virtual) RIKEN Center for Computational Science, Japan, June 3, 2020.
A. Tomiya, “Lattice gauge theory with quantum computers,” (Virtual) Osaka university, Japan, May 12, 2020.
A. Tomiya, “An introduction to deep learning (lecture),” Jamstec (Japan Agency for Marine-Earth Science and Technology), Japan,
January 13, 2019.
A. Tomiya, “An introduction to lattice gauge theories (lecture),” Math club, Tokyo, Japan, December 28, 2019.
A. Tomiya, “An introduction to deep learning (lecture),” Kochi Technological university, Kochi, Japan, December 13, 2019.
A. Tomiya, “An introduction to Machine learning and science (lecture),” Kochi Technological university, Kochi, Japan, December 13,
2019.
A. Tomiya, “An introduction to lattice gauge theories (lecture),” Jilin U, China, November 18, 2019.
A. Tomiya, “An introduction to deep learning (lecture),” Waseda U (hpc-phys working group), Japan, November 7, 2019.
A. Tomiya, “Phase transition in three flavor QCD with background magnetic field,” Jilin U, China, September 24, 2019.
A. Tomiya, “Phase transition in three flavor QCD with background magnetic field,” Keio, Japan, July 10 2019.
A. Tomiya, “Applications of machine learning to computational physics,” Brookhaven National Laboratory, NY, US, May 30, 2019.
A. Tomiya, “Towards reduction of autocorrelation in HMC by machine learning,” Riken CCS, Kobe, Japan, March 29, 2019.
A. Tomiya, “Deep Learning and Holographic QCD,” Riken, Wako, Japan, December 10, 2018.

AwardsL. Jin and K. G. Wilson, “For his outstanding contributions to the calculation of the hadronic light-by-light scattering component of theanomalous magnetic moment of the muon,” Award for Excellence in Lattice Field Theory, 2019.
L. Jin, “Lattice Calculation of the QED Correction to Meson Leptonic Decay,” U.S. Department of Energy (DOE), Early Career Research
Program, Proposal 0000253629.
S. Syritsyn, “Nucleon Structure, Fundamental Symmetries, and Lattice QCD,” U.S. National Science Foundation (NSF), Career Award
A. Tanaka and A. Tomiya, “Particle Physics Medal, Young Scientist Award in Theoretical Particle Physics,” Japan Particle and Nuclear
Theory Forum, 2019.
A. Tanaka and A. Tomiya, “Journal of the Physical Society of Japan Most Cited Articles in 2018 from Vol.86 (2017),” Journal of the
Physical Society of Japan, 2019.
T. Izubuchi, BNL Science and Technology Award, 2020.

Press Releases
https://www.bnl.gov/newsroom/news.php?a=117139
May 5, 2020, RIKEN, Brookhaven National Laboratory, Columbia University, Universities of Connecticut, Nagoya, Regensburg,“Four Years of Calculations Lead to New Insights into Muon Anomaly”- 386 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
RIKEN Facility Oﬃce at RAL
1. Abstract
Our core activities are based on the RIKEN-RAL Muon Facility located at the ISIS Neutron & Muon Source at the Rutherford
Appleton Laboratory (UK), which provides intense pulsed-muon beams. The RIKEN-RAL Muon Facility is a significant and longstanding collaboration between RIKEN and RAL in muon science—with 2020 being the 30th years of continuous agreements between
RIKEN and RAL. The Facility enables muon science throughout Japan and other field—it continues to attract proposals from a wide
variety of Japanese universities and institutions (with over 80 groups having now used the facility), and including industrial users suchat Toyota, and has been instrumental in establishing scientific links with other Asian universities.
Muons have their own spins with 100% polarization, and can detect local magnetic fields and their fluctuations at muon stoppingsites very precisely. The method to study the characteristics of materials by observing time dependent changes of muon spin polarization is called “Muon Spin Rotation, Relaxation and Resonance” (µSR method), and is applied to study electro-magnetic properties
of insulating, metallic, magnetic and superconducting systems. Muons reveal static and dynamic properties of the electronic state ofmaterials in the zero-field condition, which is the ideal magnetic condition for research into magnetism. For example, we have carriedout µSR investigations on a wide range of materials including frustrated pyrochlore systems, which have variety of exotic groundstates of magnetic spins, so the magnetism study of this system using muon is quite unique.
The ultra-cold muon beam can be stopped in thin foil, multi-layered materials and artificial lattices, which enables us to apply theaSR techniques to surface and interface science. The development of an ultra-cold muon beam is also very important as a source of
pencil-like small emittance muon beam for muon g-2/EDM measurement. We have been developing muonium generators to create
more muonium atoms in vacuum even at room temperature to improve beam quality compared with the conventional hot-tungsten
muonium generator. We have demonstrated a strong increase in the muonium emission eﬃciency by fabricating fine laser drill-holeson the surface of silica aerogel. We are also developing a high power Lyman-alpha laser in collaboration with the Advanced Photonics
group at RIKEN. The new laser will ionize muoniums 100 times more eﬃciently for slow muon beam generation.
Over the past 2–3 years, a significant development activity in muon elemental analysis has taken place, proton radius experiments
have continued and been developed, and chip irradiation experiments have also continued.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Materials science by muon-spin-relaxation method and muon site calculation
Development of elemental analysis using pulsed negative muons
Nuclear and particle physics studies via muonic atoms and ultra-cold muon beam
Other muon applications

3. Summary of Research Activity(1) Material Science at the RIKEN-RAL Muon Facility
Muons have their own spins with 100% polarization, and can detect local magnetic fields and their fluctuations at muon stoppingsites very precisely. The µSR method is applied to studies of newly fabricated materials. Muons enable us to conduct (1) material
studies under external zero-field condition, (2) magnetism studies with samples without nuclear spins, and (3) measurements of muon
spin relaxation changes at wide temperature range with same detection sensitivity. The detection time range of local field fluctuations
by µSR is 10−6 to 10−11 second, which is an intermediate region between neutron scattering method (10−10 −10−12 second) and Nuclear
Magnetic Resonance (NMR) (longer than 10−6 second). At Port-2 and 4 of the RIKEN-RAL Muon Facility, we have been performingµSR researches on strong correlated-electron systems, organic molecules, energy related materials and biological samples to study
electron structures, superconductivity, magnetism, molecular structures and crystal structures.
Among our scientific activities on µSR studies from year 2017 to 2020, following subjects of material sciences are most importantachievements at the RIKEN-RAL muon facility:(1) Deformed nodal superconducting gap state and asymmetric spin-fluctuation mediated Cooper pair in the quasi twodimensional organic superconductor λ-[BETS]2 GaCl4(2) Multi magnetic transitions in the Ru-based pyrochlore systems, R2 Ru2 O7 .
(3) Magnetic properties of the nano-cluster gold in the border of macro- and micro- scale.
(4) Novel magnetic and superconducting properties of nano-size La-based high-TC superconducting cuprates.
(5) Determination of muon positions estimated from density functional theory (DFT) and dipole-field calculations.
(6) Chemical muonic states in DNA molecules.
Result-1) We developed a novel method to determine deformed superconducting-gap structure with the density functional theory
calculations. It was concluded that the two-dimensional organic superconductor λ-[BETS]2 GaCl4 has a deformed nodal gap which
has the steeper width rather than that of the d-wave state. Result-2) Doped hole eﬀects on the magnetic properties of corner-sharedmagnetic moments on pyrochlore systems gave us new interpretations to understand exotic phenomena, like the quantum criticalityof magnetic moments and a quasi-magnetic monopole state. Result-3) and 4) The nano-size eﬀect show a new scheme of electronic
properties of metallic element. We confirmed that the nano-gold cluster can have free electronic moment on one nano-cluster. The
same nano-size eﬀect was examined on the La-based high-TC superconducting oxide changing the electronic state from insulating tosuperconducting. We confirmed the reduction in the magnetic interaction and the disappearance of the superconducting state leading- 387 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

the increase in the ferromagnetic interaction within the wide-range of the hole concentration. Result-5) Well known and deeply
investigated La2 CuO4 has opened a new scheme of the Cu spin. Taking into account quantum eﬀects to expand the Cu-spin orbital
and muon positions, we have succeeded to explain newly found muon sites and hyperfine fields at those sites.
We have been continuing to develop muon-science activities in Asian countries. We enhanced international collaborations toorganize new µSR experimental groups and to develop muon-site calculation groups using computational method. We are creating
new collaborations with new teams in diﬀerent countries and also continuing collaborations in µSR experiments on strongly correlated
systems with researchers from Taiwan, Indonesia, China, Thailand and Malaysia including graduate students. We are starting tocollaborate with the new Chinese muon group who are developing the Chinese Muon Facility and trying to develop more muon
activities in the Asian area.
(2) Development of elemental analysis using pulsed negative muons
There has been significant development of elemental analysis using negative muons on Port 4 and Port 1 over the past coupleof years. Currently, elemental analysis commonly uses X-ray and electron beams, which accurately measure surfaces. However asignificant advantage of muonic X-rays over those of electronic X-rays is their higher energy due to the mass of the muon. These highenergy muonic X-rays are emitted from the bulk of the samples without significant photon self-absorption. The penetration depth ofthe muons can be varied by controlling the muon momentum, providing data from a thin slice of sample at a given depth. This can beover a centimetre in iron, silver and gold or over 4 cm in less dense materials such as carbon.
Some techniques for elemental analysis are destructive or require the material under investigation to undergo significant treatment
and some of the techniques are only sensitive to the surface. Therefore, negative muons oﬀer a unique service in which they canmeasure inside, beyond the surface layer and completely non-destructively.
The areas of science that have used negative muons for elemental analysis have been very diverse. The largest area is the cultural
heritage community as the non-destructive ability is particularly important and will become more so. This community have investigated swords from diﬀerent eras, coins (Roman gold and silver, Islamic silver and from the Tudor Warship Mary Rose), miniatureboats from Sardinia, reliefs on Baptist church gate, Bronze Age tools and cannon balls. In addition, energy materials (Li composition
for hydrogen storage), bio-materials (search for iron to potentially help understand Alzheimer’s), engineering alloys (manufacturing
processes for new materials for jet engines), and functional materials (surface eﬀects in piezo electrics) have also been investigated.
The study was extended to see the diﬀerence by isotopes of silver and lead, which may give hint on the source of the material.
(3) Ultra-cold (low energy) Muon Beam Generation and Applications
Positive muon beam with thermal energy has been produced by laser ionization of muonium (bound system of µ+ and electron)
emitted from a hot tungsten surface with stopping surface muon beam at Port-3. The method generates a positive muon beam withacceleration energy from several 100 eV to several 10 keV, small beam size (a few mm) and good time resolution (less than 8 nsec).
By stopping the ultra-cold muon beam in thin foil, multi-layered materials and artificial lattices, we can precisely measure local
magnetic field in the materials, and apply the µSR techniques to surface and interface science. In addition, the ultra-cold muon is very
important as the source of pencil-like small emittance muon beam for muon g-2/EDM measurement. It is essential to increase the slow
muon beam production eﬃciency by 100 times for these applications. There are three key techniques in ultra-cold muon generation:
production of thermal muonium, high intensity Lyman-alpha laser and the ultra-cold muon beam line.
A high-power Lyman-alpha laser was developed in collaboration with the Advanced Photonics group at RIKEN. The new laser
system is used at J-PARC U-line and, upon completion, will ionize muoniums 100 times more eﬃciently for slow muon beam
generation. In this development, we succeeded to synthesize novel ceramic-based Nd:YGAG crystal, which realized a highly eﬃcientand stable laser system. However, larger size crystal than presently available is needed for full design power. We are working hard to
improve the crystal homogeneity including the option of using slightly diﬀerent material.
We also succeeded in developing an eﬃcient muonium generator, laser ablated silica aerogel, which emits more muoniums into
vacuum even at room temperature. Study has been done at TRIUMF utilizing positron tracking method of muon decay position.
We demonstrated in 2013 at least 10 times increase of the muonium emission eﬃciency by fabricating fine laser drill-holes on thesurface of silica aerogel. Further study was carried out in 2017 to find the optimum fabrication that will maximize the muonium
emission. From the analysis, we found the emission has large positive correlation with the laser ablated area rather than with anyother parameters. We also confirmed the muon polarization in vacuum. An alternative detection method for muonium emission using
muonium spin rotation, which will be sensitive even to muoniums near the surface, was tested at RIKEN-RAL in 2018 and was foundsuccessful. The study was further applied the measurement of the temperature dependence.
In RIKEN-RAL Port 3, the ultra-cold muon beam line, which had been designed with hot tungsten, was completely rebuilt touse advantage of the new room temperature silica aerogel target. The equipment was tested with surface muon beam and basic datasuch as muon stopping in aerogel were taken. We are waiting the laser crystal development in order to proceed to ultra-cold muon
generation. A similar target design will be adopted in the ultimate cold muon source planned for muon g-2/EDM at J-PARC.
(4) Other Fundamental Physics Studies
A measurement of the proton radius using 2S-2P transition of muonic hydrogen at PSI revealed that the proton charge radius
is surprisingly smaller than the radius measured using normal hydrogen spectroscopy and e-p scattering by more than 5 times theirexperimental precision. The muonic atom has larger sensitivity to the proton radius because the negative muon orbits closer tothe proton, although there is no reason why these measurements can yield inconsistent results if there exists no exotic physics orunidentified phenomenon behind. The cause of the discrepancy is not understood yet, thus a new measurement with independent
method is much anticipated.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

We proposed the measurement of the proton radius by using the hyperfine splitting of the muonic hydrogen ground state. This
hyperfine splitting is sensitive to the Zemach radius, which is a convolution of charge and magnetic-dipole distributions inside proton.
We are planning to re-polarize the muonic hydrogen by a circularly polarized excitation laser (excites one of the F = 1 states andregenerates the muon spin polarization), and detect the recovery of the muon decay-asymmetry along the laser.
At RIKEN, we are developing dedicated laser system (mid-infrared high-power pulse laser system at around 6 µm). We havetested the eﬃciency of our wavelength conversion scheme. We are going to test band-width narrowing using a seed laser of (Quantum
Cascade Laser) and the laser reflection cavity. Preparation using muon beam is also in progress. We measured the muon stopping
distribution in low-density hydrogen-gas cell, which gave us consistent results with beam simulation. Another key is the lifetime of
the upper hyperfine state of the muonic hydrogen that will contribute the polarization. We successfully observed the clear muon spin
precession of muonic deuterium atom in 2018 for the first time in the world. The measurement with muonic protium was carried out
in 2019.
(5) Other topics
RIKEN and ISIS have signed a new collaboration agreement for the period 2018–2023. This is the fourth in a continuous series ofagreements, the first being signed in 1990, resulting in a partnership which will have lasted over 30 years. Under the new agreement,
ownership and operation of the facility was passed to ISIS, a refurbishment programme of the facility has started, a user programme forJapanese scientists continued under the partnership between RIKEN and ISIS. The RIKEN-RAL collaboration is regularly highlighted
as a good example of UK-Japanese science partnership at the UK-Japan Joint Committee on Science and Technology (chaired by the
UK Chief Scientific Advisor to Government and a counterpart from Japan)—for example, Dr. King and Dr. Watanabe presented
RIKEN-RAL at the November 2016 meeting of the Committee. The RIKEN-RAL collaboration has also enabled the developmentof collaborative activity between RIKEN and other Asian universities, e.g. through several MoUs with Indonesian and Malaysian
universities.

Members
Director
Philip KING
Research Scientist
Isao WATANABE (Senior Research Scientist)
Contract Researcher
Katsuhiko ISHIDA

List of Publications & Presentations
Publications[Original papers]
M. Abe et al. (J-PARC E34 collaboration), “A new approach for measuring the muon’s anomalous magnetic moment and electric dipole
moment,” Prog. Theor. Exp. Phys. 2019, 053C02 (2019).
M. Clemenza et al., “Muonic atom X-ray spectroscopy for non-destructive analysis of archaological samples,” Journal of Radioanalyticaland Nuclear Chemistry 322, 1357–1363 (2019).
B. V. Hampshire, K. Butcher, K. Ishida, G. Green, D. Paul, and A. Hillier, “Using negative muons as a probe for depth profiling silver
Roman coinage,” Heritage 2, 400–407 2019.
S. Asano, K. M. Suzuki, K. Kudo, I. Watanabe, A. Koda, R. Kadono, T. Noji, Y. Koike, T. Taniguchi, S. Kitagawa, K. Ishida, andM. Fujita, J. Phys. Soc. Jpn. 88, 084709-1–6 (2019).
F. Astuti, M. Miyajima, T. Fukuda, M. Kodani, T. Nakano, T. Kambe, and I. Watanab, J. Phys. Soc. Jpn. 88, 043701-1–5 (2019).
M. A. Baqiya, T. Adachi, A. Takahashi, T. Konno, T. Ohgi, I. Watanabe, and Y. Koike, “Muon-spin relaxation study of the spin correlationsin the overdoped regime of electron-doped high-TC cuprate superconductors,” Phys. Rev. B 100, 064514-1–5 (2019).
S. Wenner, C. Marioara, K. Nishimura, K. Matsuda, S. Lee, T. Namiki, I. Watanabe, T. Matsuzaki, and R. Holmestad, “Muon spin
relaxation study of solute-vacancy interactions during natural aging of Al-Mg-Si-Cu alloys,” Metallurgical and Materials Transactions
A 50, 3446–3451 (2019).

Presentations[International conferences/workshops]
K. Ishida (oral), “Status of the g-2 and EDM experiment at J-PARC,” FCCP2019, Anacapri, Italy, August 29–31, 2019.
K. Ishida (oral), “Measurement of the proton Zemach radius from the hyperfine splitting in muonic hydrogen utilizing muon spin repolarization with laser: Principle and Method,” Proton Radius 2019, Veli Losinji, Croatia, September 15–20, 2019.
S. Kanda (oral), “Measurement of the proton Zemach radius from the hyperfine splitting in muonic hydrogen utilizing muon spin repolarization with laser: Preparation Status,” Proton Radius 2019, Veli Losinji, Croatia, September 15–20, 2019.
K. Ishida (oral), “Status of the g-2 and EDM experiment at J-PARC,” Proton Radius 2019, Veli Losinji, Croatia, September 15–20, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

K. Ishida (oral), “Laser spectroscopy of the 1 s hyperfine splitting energy of muonic hydrogen for the determination of proton Zemachradius,” The 3rd J-PARC symposium (J-PARC2019), Tsukuba, Japan, September 23–26, 2019.
I. Watanabe (oral), The 1st International MIPAnet Conference on Science and Mathematics (IMC-SciMath 2019), Parapat, Indonesia,
October 9–11, 2019.
I. Watanabe (oral), 4th Padjadjaran International Physics Symposium (PIPS2019), Bandung, Indonesia, November 13–14, 2019.
I. Watanabe (oral), International Conference on Magnetism and Its Application (IICMIA2019), Solo, Indonesia, November 20–21, 2019.

[Domestic conferences/workshops]ੴాউ඙ʢট଴ߨԋʣ, ʮӳࠃཧ‫ ݚ‬RAL ϛϡΦϯࢪઃͱϛϡΦϯར༻෼ੳʯ, ୈ 2 ճจཧ༥߹γϯϙδ΢Ϝ ྔࢠϏʔϜͰྺ࢙Λ୳Δ—Ճ଎‫͕ث‬๰͙จཧ༥߹ͷ஍ฏ—, େࡕେֶத೭ౡηϯλʔ, େࡕ, 2019 ೥ 12 ݄ 25 ೔–26 ೔.
ੴాউ඙ʢ‫ޱ‬಄ൃදʣ, ʮཧ‫ ݚ‬RAL ͷ‫ݱ‬ঢ়ͱల๬ʯ, ୈ 10 ճʮmuon ՊֶͱՃ଎‫ڀݚث‬ʯ‫ڀݚ‬ձ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2020 ೥ 1 ݄
8 ೔–9 ೔.

[Seminars]
RIKEN Symposium, “International workshop of topological quantum materials,” Tainan, Taiwan, January 10–2, 2019.
RIKEN Symposium, “The 5th international symposium in current progress in mathematics and sciences,” Depok, Indonesia, July 9–10,
2019.

AwardsS. Winarsih, RIKEN Summer School 2019, Poster Prizeʢin Physicsʣ
S. Winarsih, RIKEN Summer School 2019, Poster PrizeʢBest Presentationʣ
S. Winarsih, RIKEN Exchange Meeting 2019, Poster PrizeʢStudent Sectionʣ

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Safety Management Group
1. Abstract

The RIKEN Nishina Center for Accelerator-Based Science possesses one of the largest accelerator facilities in the world, which
consists of two heavy-ion linear accelerators and five cyclotrons. This is the only site in Japan where uranium ions are accelerated.
The center also has electron accelerators of microtron and synchrotron storage ring. Our function is to keep the radiation level inand around the facility below the allowable limit and to keep the exposure of workers as low as reasonably achievable. We are also
involved in the safety management of the Radioisotope Center, where many types of experiments are performed with sealed andunsealed radioisotopes.

2. Major Research Subjects(1) Safety management at radiation facilities of Nishina Center for Accelerator-Based Science(2) Safety management at Radioisotope Center(3) Radiation shielding design and development of accelerator safety systems

3. Summary of Research Activity

Our most important task is to keep the personnel exposure as low as reasonably achievable, and to prevent an accident. Therefore,
we daily patrol the facility, measure the ambient dose rates, maintain the survey meters, shield doors and facilities of exhaust air
and wastewater, replenish the protective supplies, and manage the radioactive waste. Advice, supervision and assistance at major
accelerator maintenance works are also our task.
The interlock system for which is the part of the radiation control system developed for the RILAC upgrade was installed andstarted to operate. Access management system for the RILAC building, which was installed previous year, was improved to control
Minor improvements of the radiation safety systems were also done. The old UPS for radiation management system of Nishinabuilding was replaced. Halogen sensitive filter for the exhaust system of Nishina building was newly installed.

Members
Director
Kanenobu TANAKA
Research/Technical Scientists
Rieko HIGURASHI (Technical Scientist)

Hisao SAKAMOTO (Technical Scientist)

Expert Technician
Atsuko AKASHIO
Technical Staﬀ I
Hiroki MUKAI
Junior Research Associate
Kenta SUGIHARA
Visiting Scientists
Masayuki HAGIWARA (KEK)
Noriaki NAKAO (Shimizu Corporation)
Toshiya SANAMI (KEK)

Nobuhiro SHIGYO (Kyushu Univ.)
Hiroshi YASHIMA (Kyoto Univ.)

Student Trainees
Shougo IZUMITANI (Kyushu Univ.)

Eunji LEE (Kyushu Univ.)

Part-time Workers
Kimie IGARASHI (Administrative Part-time Worker I)
Satomi IIZUKA (Administrative Part-time Worker II)

Yukiko SHIODA (Administrative Part-time Worker II)
Naoko USUDATE (Administrative Part-time Worker II)

Temporary Staﬃng
Ryuji SUZUKI
Assistant
Tomomi OKAYASU- 391 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

List of Publications & Presentations
Publications[Proceedings]
ాத৊৴,ʮେ‫ن‬໛Ճ଎‫ࢪث‬ઃʹ͓͚Δ, ࣄ‫࣌ނ‬ͷԁ‫ͳ׈‬δϣ౬ํ఻ୡͱආ೉ͷऔΓ૊Έʯ, ೔ຊ์ࣹઢ҆શ؅ཧֶձࢽ 18, 2 (2019).
޲Ҫ߂थ, ాத৊৴, ্ຸٛ๎,ʮRIBF Ճ଎‫ࢪث‬ઃͷྫྷ٫ਫʹؔ͢Δ์ࣹઢ؅ཧʯ, Isotope News 762, 4 (2019).

Presentations[International conferences/workshops]
K. Tanaka (oral), “Recent trouble and measures in unsealed radioisotope handling at RIBF,” International Technical Safety Forum 2019,
Lund, Sweden, May 13–17, 2019.
K. Tanaka (invited), “Radiation evaluation in RIBF,” Tsukuba, Japan, September 23–26, 2019.
K. Sugihara(poster), “Measurement of neutron energy spectra of 345 MeV/u 238 U Incidence on a Cu Target,” 2019 Symposium on Nuclear
Data, Kasuga, Japan, November 28–30, 2019.
S. Izumitani(poster), “Production via the 7 Li(p ,n) 7 Be reaction with 2.49 MeV proton injection,” 2019 Symposium on Nuclear Data,
Kasuga, Japan, November 28–30, 2019.

[Domestic conference/workshops]ాத৊৴ (ট଴ߨԋ),ʮRIBF ͷΠϯλʔϩοΫͱӡ༻ʯ, ୈ 7 ճՃ଎‫ࢪث‬ઃ҆શγϯϙδ΢Ϝ, ౦ւଜ, 2020 ೥ 1 ݄ 23–24 ೔.

Awards[Excellent poster award]
S. Izumitani, “Production via the 7 Li(p, n) 7 Be reaction with 2.49 MeV proton injection,” 2019 Symposium on Nuclear Data, Kasuga,
Japan, November 28–30, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

User Liaison Group
1. Abstract
The essential mission of the User Liaison Group is to maximize the research activities of RIBF by attracting users in various fields
with a wide scope. The Group consists of two teams. The RIBF User Liaison Team provides various supports to visiting RIBF users
through the RIBF Users Oﬃce. Managing RIBF beam time and organizing the Program Advisory Committee Meetings to review
RIBF experimental proposals are also important mission of the Team in order to enhance collaborative-use of the RIBF. The OutreachTeam has created various information materials, such as pamphlets, posters, and homepages, to introduce the research activities in
the RNC. On the homepage, we provide information on usage of the RIBF facility. The team also participate in science introduction
events hosted by public institutions. In addition, the User Liaison Group also takes care of laboratory tours for RIBF visitors frompublic. The numbers of visitors amounts to 2,300 per year.

Members
Director
Hideki UENO
Research Consultants
Ikuko HAMAMOTO (The Lund Univ.)

Munetake ICHIMURA (Univ. of Tokyo)

Assistants
Yu NAYA
Tomomi OKAYASU

Midori YAMAMOTO- 393 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

User Liaison GroupRIBF User Liaison Team
1. Abstract
To enhance synergetic common use of the world-class accelerator facility, the Radioisotope Beam Factory (RIBF), it is necessary
to promote a broad range of applications and to maximize the facility’s importance. The facilitation and promotion of the RIBF are
important missions charged to the team. Important operational activities of the team include: i) the organization of international Program Advisory Committee (PAC) meetings to review experimental proposals submitted by RIBF users, ii) RIBF beam-time operation
management, and iii) promotion of facility use by hosting outside users through the RIBF Independent Users program, which is a
new-user registration program begun in FY2010 at the RIKEN Nishina Center (RNC) to enhance the synergetic common use of the
RIBF. The team opened the RIBF Users Oﬃce in the RIBF building in 2010, which is the main point of contact for Independent Usersand provides a wide range of services and information.

2. Major Research Subjects(1) Facilitation of the use of the RIBF
(2) Promotion of the RIBF to interested researchers

3. Summary of Research Activity(1) Facilitation of the use of the RIBF
The RIBF Users Oﬃce, formed by the team in 2010, is a point of contact for user registration through the RIBF Independent User
program. This activity includes:• registration of users as RIBF Independent Users,• registration of radiation workers at the RIKEN Wako Institute,• provision of an RIBF User Card (a regular entry permit) and an optically stimulated luminescence dosimeter for each RIBF
Independent User, and• provision of safety training for new registrants regarding working around radiation, accelerator use at the RIBF facility, andinformation security, which must be completed before they begin RIBF research.
The RIBF Users Oﬃce is also a point of contact for users regarding RIBF beam-time-related paperwork, which includes:• contact for beam-time scheduling and safety review of experiments by the In-House Safety Committee,• preparation of annual Accelerator Progress Reports, and• maintaining the above information in a beam-time record database.
In addition, the RIBF Users Oﬃce assists RIBF Independent Users with matters related to their visit, such as invitation procedures,visa applications, and the reservation of on-campus accommodation.
(2) Promotion of the RIBF to interested researchers• The team has organized an international PAC for RIBF experiments; it consists of leading scientists worldwide and reviews
proposals in the field of nuclear physics (NP) purely on the basis of their scientific merit and feasibility. The team also assists
another PAC meeting for material and life sciences (ML) organized by the RNC Advanced Meson Laboratory. The NP and ML
PAC meetings are organized twice a year.
• The team coordinates beam times for PAC-approved experiments and other development activities. It manages the operatingschedule of the RIBF accelerator complex according to the decisions arrived at by the RIBF Machine Time Committee.
• To promote research activities at RIBF, proposals for User Liaison and Industrial Cooperation Group symposia/mini-workshops
are solicited broadly both inside and outside of the RNC. The RIBF Users Oﬃce assists in the related paperwork.
• The team is the point of contact for the RIBF users’ association. It arranges meetings at RNC headquarters for the RIBF User
Executive Committee of the users’ association.
• The Team conducts publicity activities, such as arranging for RIBF tours, development and improvement of the RNC oﬃcial web
site, and delivery of RNC news via email and the web.

Members
Team Leader
Ken-ichiro YONEDA
Contract Researcher
Tadashi KAMBARA- 394 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

User Liaison Group
Outreach Team
1. Abstract
The Outreach Team has created various information materials to introduce research activities in the RNC. For instance, the teammakes brochures introducing the RNC and the RIBF accelerator facility, posters of symposia and the summer school hosted by RNC,
the center homepage containing information such as details of RNC and the procedure for the use of the RIBF facility, and images ofequipment and facilities available for researchers inside and outside RIKEN, among the others. Furthermore, the team also participatesin science introduction events hosted by public institutions.

2. Major Work Contents
The major work contents of the Outreach Team is to promote the publicity of RNC, through the creation of various materials suchas brochures, websites, posters, and videos, among the others. The arrangement of tours of the RIBF facility and the exhibition andintroduction of the RIBF facility at science events are also conducted independently or in cooperation with RIKEN Public Relations
Oﬃce.

3. Summary of Work Activity
The specific work contents performed by the team are as follows:• [Website] The Team creates/manages the RNC oﬃcial website (http://www.nishina.riken.jp), which introduces the organization and its research activities. This website plays an important role in providing information to researchers who visit RNC
to conduct his/her own research.
• [Brochures] The Team has produced various brochures introducing the organization and the studies performed at RNC. The
brochures named “Your body is made of star scraps” explaining element synthesis in the universe and “Introduction of RIBF
Facility” in a cartoon style for children are among them.
• [Posters] Conference/Symposium posters connected with RNC were prepared on the request of organizers. For general purpose,a special poster featuring the nuclear chart has been prepared for distribution. In commemoration of the discovery of nihonium,
brochures and posters dedicated to the ceremony were made.
• [RIBF Cyclopedia] In April 2012, the permanent exhibition hall (RIBF Cyclopedia) located at the entrance hall of the RIBF
building was set up in cooperation with RIKEN Public Relations Oﬃce. Explanatory illustrations on nuclear science, research at
RIBF, RIBF history, a 3D nuclear chart built with LEGO blocks, and a 1/6-size GARIS model are displayed to help understanding
through visual means. The Team is also working on updating the exhibits.
• [RIBF facility tour] The Team arranges RIBF facility tour for over 2000 visitors per year. The tour is guided by a researcher.
• [Science event participation] In 2010, 2012, 2013, 2015, and 2016, the sub-team opened an exhibition booth of RNC to introduce
the latest research activities on the occasion of the “Science Agora” organized by Japan Science and Technology Agency (JST).
From time to time, the sub-team was invited to participate in scientific events by MEXT, Wako city, and Nissan global foundation.
One attraction targeting children is the hands-on work of assembling “Iron-beads” to create a nuclear chart or a shape of nihonium.
In addition to the above-noted work contents, the Team conducts a variety of works, such as taking pictures of meetings organized by
RNC, cooperation in the production of a 3D video to explain the accelerators and the research at RIBF, among the others.

Members
Team Leader
Hideki UENO
Deputy Team Leader
Yasushi WATANABE
Technical Staﬀ I
Narumasa MIYAUCHI

List of Publications & Presentations
Outreach activities
Special Exhibition of the International Year of the Periodic Table 2019ʢࠃࡍप‫ظ‬ද೥ಛผల 2019ʮཧԽֶ‫ॴڀݚ‬ͷχϗχ΢Ϝ໛‫ܕ‬Λͭ͘Ζ͏ʯʣ, Niihama (Ehime Prefectural Science Museum), January 18–19, 2020.
RIKEN Osaka Campus Open Day 2019, Suita, November 23, 2019.
Science Agora 2019 (an open forum organized by the Japan Science and Technology Agency), Tokyo (The National Museum of Emerging
Science and Innovation), November 15–17, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Oﬃce of the Center Director
Summary of Research Activity
This oﬃce is in place from JFY2018 to support the center director in subjects which the promotion oﬃce is not able to cover. It
also works as a home laboratory for research administrators and assistants with an indefinite term contract. This year’s most important
activity of the oﬃce was to support the International Symposium on Superheavy Elements (SHE2019) held at Hakone, Japan from 1st
to 5th of December 2019. The Chair parsons K. Morita and H. Haba run the symposium and were supported largely by this oﬃce;
research administrator Narumasa MIYAUCHI and assistants Noriko ASAKAWA and Noriko KIYAMA. Miyachi also contributed
largely to the International Year of Periodic table (IYPT2019), in the preparation of the travelling exhibitions and the preparationof the session “Creation of superheavy elements” in the IYPT2019 Closing Ceremony. His handmade video of “The Landscape of
Nihonium Avenue” was greatly appreciated by the audience. Below is a list of activity of Nishina Center Director’s Oﬃce, in public
or semi-public events.
2019.03.01

NuPECC at Warsaw

2019.03.11
2019.03.17

RBRC SRC
JPS meeting at Ito Campus,
Kyushu University

2019.04.17

Nishina Center,
New-commers’ Orientation
Completion Ceremony for
Nihonium Avenue

2019.05.19

2019.05.29

ORNL visit

2019.06.11

Sakura Science High School
Visit

2019.06.24

NCAC

2019.06.28

ML-PAC

2019.07.10

IN-PAC

2019.07.27

Mendeleev 150

2019.08.01

SCK-CEN visit

2019.08.02

IUPAP-WG9

2019.08.21

NICT Visit

2019.08.26

TAN19

2019.09.07

IYPT2019 Special Exhibition
in Kyoto

2019.10.03

J. Soffer’s Memorial2019.10.23
2019.11.00

RAC
Chemistry and Chemical
Industry

Nishina Center is the associate member of (NuPECC: Nuclear Physics European Collaboration
Committee, an Expert Committee of the European Science Foundation). The status report ofNishina Center was presented at their regular meeting at Warsaw, Poland. The minutes areavailable in http://www.nupecc.org/misc/min94.pdf
Nishina Director participated in Scientific Review Committee of RIKEN-BNL Research Center.
As recommended by Nishina Center, Japan Physics Society organized a special joint session for
IYPT2019 at the Ito Campus of Kyushu University with the Chemical Society of Japan at
Kobe-Okamoto Campus of Konan University. K. Morita gave a plenary talk.
In the orientation for new commers in Nishina Center, introductory talk of “Researcher’s MustHave” was given by Nishina Director.
Wako City held the Completion Ceremony of Nihonium Avenue in the RIKEN Wako Campus.
The Mayer Matsumoto invited the donors and students to the Ceremony. The Nishina Director
gave the presentation of “Welcome to the birthplace of 113th element, nihonium (in Japanese)”.
Many of audience also attended the challenge exam for chemical elements, held together with the
ceremony.
Nishina Director visited Oak Ridge National Laboratory to participate in the collaboration
meeting for superheavy element search.
Sakura Science High School, a government-driven virtual school for foreign exchange Students,
visited RIKEN. Nishina Director gave a presentation of “Welcome to the birthplace of 113th
element, nihonium”.
Nishina Center Advisory Committee was held. Nishina Director and the Center activities werereviewed for three days.
Nishina Director gave an introductory talk for ML-PAC (Program Advisory Committee forMaterials and Life Science).
Nishina Director gave an introductory talk for In-PAC( Program Advisory Committee forIndustrial usage), which was held in a closed session.
4th International Conference on the Periodic Table (Mendeleev 150) was held at ITMO University
in Saint Petersburg, Russian Federation (see https://mendeleev150.ifmo.ru/). Nishina Director
gave a lecture titled “History of Nihonium” on behalf of Kosuke Morita. The talk was publishedin https://doi.org/10.1515/pac-2019-0810
Nishina Director visited CNK-CEN which is the Belgian nuclear research centre, to seek forpossible collaboration in MYRRHA(Multi-purpose hYbrid Research Reactor for High-tech
Application).
Nishina Director participated in the annual general meeting for IUPAP-WG9 (Working Group 9)
held at University of Notre Dame in London, UK. Agenda is available athttps://iupap.triumf.ca/icnp/meetings.html.
A delegation from NICT (National Institute of Information and Communication Technology)
visited Nishina Center. Nishina Director made an introduction to them with a story of the first
cyclotron made by Nishina was made on the Paulsen’s arc converted which was developed forradio communication.
Tan19(6th International Conference on the Chemistry and Physics of the Transactinide Elements)
was held in Wilhelmshaven, Germany. Nishina Director was invited to give a lecture “Element
Genesis over 13.8 Billion Universal Years” in a session dedicated to the International Year of
Periodic Table: https://www-win.gsi.de/tan19/symposium.html.
Nishina Director gave a public lecture in the Special Exhibition in Kyoto for the InternationalYear of Periodic Table, titled “13.8 billion years of element genesis, from Big-Bang to nihonium( in Japanese)”.
Nishina Director participated in a memorial symposium for J. Soffer, who was a leading theoristof perturbative QCD and the father of the RHIC spin project, at BNL, NY, USA.
Nishina director gave a presentation in RIKEN Advisory Council.
Nishina Director contributed a report of Mendeleev150 Symposium to the special contents for
IYPT2019 in Chemistry and Chemical Industry, 940, Vol72-11, 2019.

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Ⅵ. RNC ACTIVITIES2019.11.25

Event Myrrha

2019.12.05

IYPT2019 Closing Ceremony

2019.12.01

SHE20192019.12.16

NP-PAC

2020.01.24

ML-PAC

2020.01.00

Nuclear Physics News

2020.01.27

Strategic review of Helmholtz
Association

RIKEN Accel. Prog. Rep. 53

Nishina Director participated in Event MYRRHA (introduction of MYRRHA project to Japanesecommunities) held at Belgian Embassy at Tokyo, Japan
Nishina director was a port of the organizing committee for the closing ceremony of IYPT2019,held in Tokyo, Japan. He produced and chaired a session named “Creation of superheavy
elements” attended by many of actual discoverers. https://iypt.jp
Director’s office fully supported the international Symposium on Superheavy Elements(SHE2019) held at Hakone, Japan from 1st to 5th of December 2019. The Chair parsons are K.
Morita and H. Haba. https://she2019.riken.jp
Nishina Director gave an introductory talk for NP-PAC (Program Advisory Committee for
Nuclear Physics).
Nishina Director gave an introductory talk for ML-PAC (Program Advisory Committee forMaterials and Life Science).
Nishina Director reported “Superheavy Elements at the Closing Ceremony of IYPT” to Nuclear
Physics News, Vol. 30, No. 1, 2020.
Nishina Director visited Helmholtz Association in Berlin, Germany, to review of the scientificfield “MATTER” which includes GSI, DESY and other large-scale laboratories

Members
Director
Hideto EN’YO
Research Administrator
Narumasa MIYAUCHI (concurrently appointed to OutreachTeam)
Assistants
Noriko ASAKAWA
Noriko KIYAMAYu NAYA (concurrently appointed to RIBF User Liaison
Team)
Karen SAKUMA (concurrently appointed to Accelerator
Group)

Asako TAKAHASHI (concurrently appointed to Spin Isospin
Laboratory)
Mitsue YAMAMOTO (concurrently appointed to Meson Science Laboratory)
Izumi YOSHIDA (concurrently appointed to Nuclear Spectroscopy Laboratory)

List of Publications & Presentations
Publications[Proceedings]
Hideto En’yo (invited), “History of nihonium,” Proceedings of Mendeleev 150, Pure and Applied Chemistry, 91, 1941 (2019).

Presentations[International conferences/workshops]
Hideto En’yo (invited), “History of nihonium,” 4th International Conference on the Periodic Table (Mendeleev 150), ITMO University inSaint Petersburg, Russian Federation, July 26–28, (2019).
Hideto En’yo (invited), “Element genesis over 13.8 billion Universal years,” Special Symposium for International Year of Periodic Tablein the 6th International Conference on the Chemistry and Physics of the Transactinide Elements (TAN19), Wilhelmshaven, Germany,
August 25–30, 2019.

Outreach activities
Hideto En’yo, “Welcome to the birthplace of 113th element, nihonium,” a lecture given to the Sakura Science High School, RIKEN-Wako,
June 11, 2019.
Hideto En’yo et al. (invited), “Creation of superheavy elements,” The Closing Ceremony of IYPT2019, Tokyo, Japan, December 5, 2019.
Hideto En’yo, “Superheavy Elements at the Closing Ceremony of IYPT” contributed to Nuclear Physics News 30, 39 2020.
Ԇᢛलਓ, ʮΑ͏ͦ͜, 113 ൪‫ݩ‬ૉχϗχ΢Ϝͷੜ஀஍, ཧ‫ݚ‬ਔՊηϯλʔ΁ʯ, χϗχ΢Ϝ௨Γ‫׬‬੒‫ه‬೦ࣜయʢ࿨ޫࢢओ࠵ʣ, ཧ‫ݚ‬࿨ޫΩϟϯύε, ࿨ޫ, 2019 ೥ 5 ݄ 19 ೔.
Ԇᢛलਓ, ʮ‫ݩ‬ૉ૑੒ͷ 138 ԯ೥: Ϗοάόϯ͔Βχϗχ΢ϜʹࢸΔ·Ͱʯ, ࠃࡍप‫ظ‬ද೥ 2019 ಛผల, ‫౎ژ‬େֶ, ‫౎ژ‬, 2019 ೥ 9
݄ 7 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Partner Institutions

The Nishina Center started research collaboration with universities and research institutes in 2008 under the “Research Partnership”
agreement. This collaboration framework permits an external institute to develop its own projects at the RIKEN Wako campus inequal partnership with the Nishina Center. At present, two institutes, the Center for Nuclear Study (CNS), the University of Tokyo;
and the Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High-energy Accelerator Research
Organization (KEK) are conducting research activities under the “Research Partnership” agreement.
The CNS and the Nishina Center signed the partnership agreement in 2008. Until then, the CNS had collaborated in joint programswith RIKEN under the “Research Collaboration Agreement on Heavy Ion Physics” (collaboration agreement) signed in 1998. The
partnership agreement redefines procedures related to the joint programs while keeping the spirit of the collaboration agreement. The
joint programs include experimental nuclear-physics activities using CRIB, SHARAQ, and GRAPE at RIBF, accelerator development,
and activities at RHIC PHENIX.
KEK started low-energy nuclear physics activity at RIBF in 2011 under the Research Partnership System. The joint experimental
programs are based on KISS (KEK Isotope Separator). After the R&D studies on KISS, it became available for users from 2015.
The experimental proposals that request the use of the above-noted devices of the CNS and KEK together with the other RIBF
key devices are screened by the Program Advisory Committee for Nuclear Physics experiments at RI Beam Factory (NP-PAC) The
NP-PAC meetings are co-hosted together with the CNS and KEK.
The activities of the CNS and KEK are reported in the following pages.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Partner Institution
Center for Nuclear Study, Graduate School of Science
The University of Tokyo
1. Abstract

The Center for Nuclear Study (CNS) aims to elucidate the nature of nuclear system by producing the characteristic states where
the Isospin, Spin and Quark degrees of freedom play central roles. These researches in CNS lead to the understanding of the matterbased on common natures of many-body systems in various phases. We also aim at elucidating the explosion phenomena and theevolution of the universe by the direct measurements simulating nuclear reactions in the universe. In order to advance the nuclear
science with heavy-ion reactions, we develop AVF upgrade, CRIB and SHARAQ facilities in the large-scale accelerators laboratories
RIBF. The OEDO facility has been developed as an upgrade of the SHARAQ, where a RF deflector system has been introduced toobtain a good quality of low-energy beam. A new project for fundamental symmetry using heavy RIs has been starting to install new
experimental devices in the RIBF. We promote collaboration programs at RIBF as well as RHIC-PHENIX and ALICE-LHC with
scientists in the world, and host international meetings and conferences. We also provide educational opportunities to young scientists
in the heavy-ion science through the graduate course as a member of the department of physics in the University of Tokyo and throughhosting the international summer school.

2. Major Research Subjects(1) Accelerator Physics(2) Nuclear Astrophysics(3) Nuclear spectroscopy of exotic nuclei(4) Quark physics(5) Nuclear Theory(6) OEDO/SHARAQ project(7) Exotic Nuclear Reaction(8) Low Energy Nuclear Reaction Group(9) Active Target Development(10) Fundamental Physics

3. Summary of Research Activity(1) Accelerator Physics
One of the major tasks of the accelerator group is the AVF upgrade project that included development of ion sources. In 2019, theoperating time of the HyperECR was 2326 hours, which is 76% of the total operating time of the AVF cyclotron. The beam extraction
system of the HyperECR is under development realize a high intensity and low emittance beam. For the pepper-pot emittance monitor
used for the analysis of the beam injection transport system, we optimized the exposure time and gain of digital camera for a varietyof thicknesses of fluorescent agent and was able to keep homogenized measurements despite of thickness. For the beam transport
analysis of the beamline to CRIB, E7B, and EDM experiment from AVF cyclotron, we started developing 4D emittance monitor
because the transverse components of beam are coupled and it is expected to measure high intensity beam in a few seconds.
(2) Nuclear Astrophysics
The main activity of the nuclear astrophysics group is to study astrophysical reactions and special nuclear clustering using the
low-energy RI beam separator CRIB. Several experimental projects on big-bang nucleosynthesis (BBN) are currently under way. To
give a solution to the cosmological 7 Li abundance problem, 7 Be(n, α)/(n, p) astrophysical reactions were studied with the Trojan
Horse method, and the rate of 7 Be(n, p1 ), the (n, p) reaction with 7 Li excitation, is evaluated at the BBN temperature for the first time.
7
Be(d, p) measurement with a 7 Be-implanted target was carried out in 2018, in collaboration with RCNP, Osaka Univ. and JAEA.
8
Li(α, n) reaction has been considered as responsible to the production of nuclei heavier than boron in some models of the BBN. To
solve the discrepancy between the previous measurements of 8 Li(α, n), a new experiment with γ-ray measurement was performed
at CRIB in September 2018. To confirm the exotic linear-chain cluster structure in 14 C nucleus indicated in the previous 10 Be + α
resonant scattering measurement at CRIB, a new measurement was carried out at INFN-LNS, Catania, Italy, under the collaborationof CNS, INFN, Univ. Edinburgh and other institutes, in October 2018. A measurement on 25 Al + p resonant scattering was performed
at CRIB in February 2019, to study the resonances relevant for the astrophysical 22 Mg(α, p) reaction in X-ray bursters.
The main activity of the nuclear astrophysics group is to study astrophysical reactions and special nuclear clustering using the lowenergy RI beam separator CRIB. As the first experiment of the INSPIRATION project, a measurement of the proton-halo 8 B+120 Sn
system at energies around the Coulomb barrier was carried out in April 2019, under the collaboration of Japan and China. This wasto study the reaction mechanism, including the break-up, of the system involving a weakly-bound nucleus, 8B. On the interest of
nuclear clustering in the 14 O nucleus, a measurement of 10 C+α elastic scattering was performed, under the collaboration of Belgium(ULB), Kyoto Univ., Osaka Univ., CNS, and other groups. We identified several peaks in the energy spectrum, which may show theexistence of cluster states. Studies on big-bang nucleosynthesis (BBN) are currently under way. To give a solution to the cosmological7
Li abundance problem, 7 Be(n, α)/(n, p) astrophysical reactions were measured with the Trojan Horse method, and the first reliableevaluation of the rate of 7 Be(n, p1), the (n, p) reaction with 7 Li excitation, at the BBN temperature, was made during 2019. To produce- 400 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

RI beams at CRIB with higher intensity, a project to improve the heat capacity of the cryogenic gas target was initiated in 2019. We
tested several materials for the sealing foils and the flanges, and a thermal monitoring with a thermography was introduced.
(3) Nuclear structure of exotic nuclei
The NUSPEQ (NUclear SPectroscopy for Extreme Quantum system) group studies exotic structures in high-isospin and/or highspin states in nuclei. The CNS GRAPE (Gamma-Ray detector Array with Position and Energy sensitivity) is a major apparatus forhigh-resolution in-beam gamma-ray spectroscopy. Missing mass spectroscopy using the SHARAQ is used for another approach on
exotic nuclei. The group plays a major role in the OEDO/SHARAQ project described below. In 2019, analysis of a new measurementof the 4 He(8 He, 8 Be)4n reaction for better statistics and better accuracy has been proceeding.
(4) Quark Physics
Main goal of the quark physics group is to understand the properties of hot and dense nuclear matter created by colliding heavy
nuclei at relativistic energies. The group has been involved in the PHENIX experiment at Relativistic Heavy Ion Collider (RHIC) at
Brookhaven National Laboratory, and the ALICE experiment at Large Hadron Collider (LHC) at CERN. As for ALICE, the group has
involved in the data analyses, which include the measurement of low-mass lepton pairs in Pb-Pb and p-Pb collisions, J/ψ measurements in p-Pb collisions, long range two particle correlations in p-Pb collisions, and searches for thermal photons in p-Pb collisions.
The group has been involved in the ALICE-TPC upgrade using a Gas Electron Multiplier (GEM). Installation of GEM chambers in
the TPC and commissioning of the TPC were carried out in 2019. The group has started working on the online space-charge distortion
correction of the TPC by utilizing the GPUs and Machine learning technique.
(5) Nuclear Theory
The nuclear theory group participated in a project, “Priority Issue 9 to be tackled by using the Post-K Computer” and promotes
computational nuclear physics utilizing supercomputers. We developed shell-model codes for the conventional Lanczos method andthe Monte Carlo shell model for massively parallel computation. In FY2019, we performed the Monte Carlo shell model calculationsof the Sm isotopes and revealed that the excited states of 154 Sm and 166 Er whose structures were considered to be β/γ vibration can beinterpreted in view of shape coexistence.
(6) OEDO/SHARAQ project
The OEDO/SHARAQ group pursues experimental studies of RI beams by using the high-resolution beamline and the SHARAQ
spectrometer. A mass measurement by TOF-Bρ technique for very neutron-rich successfully reaches calcium isotopes beyond N = 34,
55, 57Ca, and the preparation of publication is ongoing. The experimental study of 0− strength in nuclei using the parity-tansfer charge
exchange (16 O, 16 F) is on progress and the data analysis is on the final stage. The OEDO beamline, which was an upgrade of the highresolution beamline to produce low-energy RI beams, has started the operation in June and has successfully achieved the designed
ion-optical performance. The first and second experiments were performed in October and November, and new data for nuclear
transmutation of long lived fission products (LLFPs) were successfully obtained.
(7) Exotic Nuclear Reaction
The Exotic Nuclear Reaction group studies various exotic reactions induced by beams of unstable nuclei. One subject is inversekinematics (p, n) reaction. In 2017 a set of neutron counters PANDORA was used for the first time at HIMAC facility for the study ofthe 6 He(p, n) reaction. Candidate nuclei to study are high spin isomers such as 52 Fe(12+ ). Development of isomer beam was carriedout.
(8) Low Energy Nuclear Reaction GroupA recoil particle detector for missing mass spectroscopy, named TiNA, had been developed under the collaboration with RIKEN
and RCNP. TiNA consists of 6 sector telescopes. Each of which as a stripped-type SSD and 2 CsI(Tl) crystals. After the test experimentat the tandem facility of Kyushu Univ., TiNA was employed at the physics experiment with OEDO. Development of the tritium target
is still on-going. Several deuterium doped Ti targets were fabricated at the Toyama Univ. They were tested by using d(12 C, d) reaction
at the tandem facility at Kyushu. The amount of deuterium was found to be scattered. The optimum condition to make the target will
be sought for. The production cross section 178m2 Hf was evaluated for the mass production in the future. The digital signal processing
devices for the GRAPE have been developed to measure the cascade transitions from the isomeric state. After chemical separation of
Hf at the hot laboratory at RIBF. The week cascade decay was successfully measured.
(9) Active Target Development
Two types of gaseous active target TPCs called CAT’s and GEM-MSTPC are developed and used for the missing mass spectroscopy. The CAT’s are employed for the study of equation of state of nuclear matter. The measurement of giant monopole resonancein 132 Sn at RIBF with CAT-S and the data analysis is ongoing. In 2017, we developed a larger active target called CAT-M, which has
10-times larger active volume than that of CAT-S. The CAT-M was commissioned at HIMAC and the excitation energy spectrum of136
Xe for proton scattering was measured. The GEM-MSTPC is employed for the nuclear astrophysics study. The data analysis of(α, p) reaction on 18 Ne and 22 Mg and the β-decay of 16 Ne followed by α emission are ongoing.
(10) Fundamental Physics
Although the Standard Model of particle physics is being steadily and successfully verified, the disappearance of the antimatterin the universe could not be suﬃciently explained; a more fundamental framework is required and has to be studied. In order to- 401 -

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understand the mechanism of matter-antimatter symmetry violation, we are developing the next generation experiments employing
ultracold atoms to search for the electron electric dipole moment (EDM) using heavy element francium (Fr) in an optical latticeat RIBF. In 2019, we developed a surface ionizer for production of a high intensity Fr ion beam. Using the surface ionizer, the
1st Fr production experiment was also conducted in 2019. At present, the development of a magneto-optical trap and an atomic
interferometer are in progress.

Members
Director
Susumu SHIMOURA
Scientific Staﬀ
Susumu SHIMOURA (Professor)
Yasuhiro SAKEMI (Professor)
Nobuaki IMAI (Associate Professor)
Kentaro YAKO (Associate Professor)
Taku GUNJI (Associate Professor)

Noritaka SHIMIZU (Project Associate Professor)
Hidetoshi YAMAGUCHI (Lecturer)
Shin’ichiro MICHIMASA (Assistant Professor)
Shinsuke OTA (Assistant Professor)
Hiroki NAGAHAMA (Assistant Professor)

Guest Scientists
Yutaka UTSUNO (Guest Professor)
Daiki NISHIMURA (Guest Associate Professor)

Toshitaka KAJINO (Guest Post Doctoral Associate)

Technical Staﬀ
Yasuteru KOTAKA
Techinical Assistants
Yukimitsu OHSHIRO

Masayoshi YAGYU

Project Research Associates
Masanori DOZONO
Seiya HAYAKAWA

Takashi ABE

Post Doctoral Associates
Shinichi HAYASHI
Daiki SEKIHATA
Keisuke NAKAMURA
Keita KAMAKURA
Jongwon HWANG
Nanru MA

Yusuke TSUNODA
Kota YANASE
Laszlo STUHLLei YANG
Javier MENÉNDEZ

Assistant Teaching Staﬀ
Yuko SEKIGUCHI
Academic Support Staﬀ
Reiko KOJIMA

Chihiro IWAMOTO

Graduate Students
Shoichiro MASUOKA
Noritaka KITAMURA
Keita KAWATA
Hideki SHIMIZU

Rieko TSUNODA
Naoya OZAWA
Shutaro HANAINatsuki SHIMIZU

Administration Staﬀ
Toshio OSUGI
Ikuko YAMAMOTO

Takako ENDO
Yukino KISHI- 402 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

List of Publications & Presentations
Publications[Original papers]
K. Nakano, Y. Watanabe, S. Kawase, H. Wang, H. Otsu, H. Sakurai, S. Takeuchi, Y. Togano, N. Nakamura, M. Maeda, D. S. Ahn,
M. Aikawa, S. Araki, S. Chen, N. Chiga, P. Doornenbal, N. Fukuda, T. Ichihara, T. Isobe, S. Kawakami, T. Kin, Y. Kondo, S. Koyama,
T. Kubo, S. Kubono, M. Uesaka, A. Makinaga, M. Matsushita, T. Matsuzaki, S. Michimasa, S. Momiyama, S. Nagamine, M. Niikura,T. Ozaki, A. Saito, T. Saito, Y. Shiga, M. Shikata, Y. Shimizu, S. Shimoura, T. Sumikama, P. A. Söderström, H. Suzuki, H. Takeda,
R. Taniuchi, J. Tsubota, Y. Watanabe, K. Wimmer, T. Yamamoto, and K. Yoshida, “Isotope production in proton-, deuteron-, andcarbon-induced reactions on 93 Nb at 113 MeV/nucleon,” Phys. Rev. C 100, 044605 (2019).
A. Corsi, Y. Kubota, J. Casal, M. Gómez-Ramos, A. M. Moro, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono,
J. Feng, F. Flavigny, J. -M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim,
Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F. M. Marques,
T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, N. A. Orr, S. Ota, H. Otsu, T. Ozaki,
V. Panin, S. Paschalis, E. C. Pollacco, S. Reichert, J. - Y. Rousse, A. T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano,
H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y. L. Sun, M. Tabata, Y. Togano, J. Tsubota, T. Uesaka, Z. H. Yang,
J. Yasuda, K. Yoneda, and J. Zenihiro, “Structure of 13 Be probed via quasi-free scattering,” Phys. Lett. B 797, 134843 (2019).
M. Mazzocco, N. Keeley, A. Boiano, C. Boiano, M. La Commara, C. Manea, C. Parascandolo, D. Pierroutsakou, C. Signorini, E. Strano,
D. Torresi, H. Yamaguchi, D. Kahl, L. Acosta, P. Di Meo, J. P. Fernandez-Garcia, T. Glodariu, J. Grebosz, A. Guglielmetti, Y. Hirayama,
N. Imai, H. Ishiyama, N. Iwasa, S. C. Jeong, H. M. Jia, Y. H. Kim, S. Kimura, S. Kubono, G. La Rana, C. J. Lin, P. Lotti, G. MarquinezDuran, I. Martel, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, A. Pakou, K. Rusek, Y. Sakaguchi, A. M. Sanchez-Bentez, T. Sava,
O. Sgouros, V. Soukeras, F. Soramel, E. Stiliaris, L. Stroe, T. Teranishi, N. Toniolo, Y. Wakabayashi, Y. X. Watanabe, L. Yang,
Y. Y. Yang, and H. Q. Zhang, “Elastic scattering for the 8 B and 7 Be + 208 Pb systems at near-Coulomb barrier energies,” Phys. Rev. C
100, 024602 (2019).
H. Wang, H. Otsu, N. Chiga, S. Kawase, S. Takeuchi, T. Sumikama, S. Koyama, H. Sakurai, Y. Watanabe, S. Nakayama, D. S. Ahn,
H. Baba, S. D. Chen, K. Chikaato, M. L. Cortés, N. Fukuda, A. Hirayama, R. Hosoda, T. Isobe, S. Kawakami, Y. Kondo, S. Kubono,
Y. Maeda, S. Masuoka, S. Michimasa, I. Murray, R. Nakajima, T. Nakamura, K. Nakano, M. Nishimura, T. Ozaki, A. Saito, T. Saito,
H. Sato, Y. Shimizu, S. Shimoura, P. A. Söderström, Y. Soudo, X. H. Sun, J. Suwa, D. Suzuki, H. Suzuki, H. Takeda, M. Takechi,
Y. Togano, T. Tomai, H. Yamada, M. Yasuda, and K. Yoshida “Enhancement of element production by incomplete fusion reaction withweakly bound deuteron,” Commun. Phys. 2, Article number 78 (2019).
R. Taniuchi, C. Santamaria, P. Doornenbal, A. Obertelli, K. Yoneda, G. Authelet, H. Baba, D. Calvet, F. Chateau, A. Corsi, A. Delbart,
J. -M. Gheller, A. Gillibert, J. D. Holt, T. Isobe, V. Lapoux, M. Matsushita, J. Menéndez, S. Momiyama, T. Motobayashi, M. Niikura,
F. Nowacki, K. Ogata, H. Otsu, T. Otsuka, C. Peron, S. Peru, A. Peyaud, E. C. Pollacco, A. Poves, J. - Y. Rousse, H. Sakurai,
A. Schwenk, Y. Shiga, J. Simonis, S. R. Stroberg, S. Takeuchi, Y. Tsunoda, T. Uesaka, H. Wang, F. Browne, L. X. Chung, Z. Dombradi,
S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadynska-Klek, Z. Korkulu, S. Koyama, Y. Kubota, J. Lee, M. Lettmann, C. Louchart,
R. Lozeva, K. Matsui, T. Miyazaki, S. Nishimura, L. Olivier, S. Ota, Z. Patel, E. Sahin, C. Shand, P. -A. Söderström, I. Stefan,
D. Steppenbeck, T. Sumikama, D. Suzuki, Z. Vajta, V. Werner, J. Wu, and Z. Y. Xu, “78 Ni revealed as a doubly magic stronghold
against nuclear deformation,” Nature 569, 53 (2019).
N. Paul, A. Obertelli, C. A. Bertulani, A. Corsi, P. Doornenbal, J. L. Rodriguez-Sanchez, G. Authelet, H. Baba, D. Calvet, F. Chateau,
S. Chen,, A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama,, T. Motobayashi,
M. Niikura, H. Otsu, C. Peron, A. Peyaud, E. C. Pollacco, J. -Y. Rousse, H. Sakurai, C. Santamaria, M. Sasano, Y. Shiga, D. Steppenbeck, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, T. Ando,, T. Arici, A. Blazhev, F. Browne, A. M. Bruce, R. Carroll,
L. X. Chung, M. L. Cortes,,, M. Dewald, B. Ding, Zs. Dombradi, F. Flavigny, S. Franchoo, F. Giacoppo, M. Gorska, A. Gottardo,
K. Hadynska- Klek, Z. Korkulu, S. Koyama,, Y. Kubota,, A. Jungclaus, J. Lee, M. Lettmann, B. D. Linh, J. Liu, Z. Liu, C. Lizarazo,
C. Louchart, R. Lozeva,, K. Matsui, T. Miyazaki, K. Moschner, S. Nagamine,, N. Nakatsuka, C. Nita, S. Nishimura, C. R. Nobs,
L. Olivier, S. Ota, Z. Patel, Zs. Podolyak, M. Rudigier, E. Sahin, T. Y. Saito,, C. Shand, P. -A. Söderström, I. G. Stefan, T. Sumikama,
D. Suzuki, R. Orlandi, V. Vaquero, Zs. Vajta, V. Werner, K. Wimmer, J. Wu, and Z. Xu, “Prominence of Pairing in Inclusive (p, 2p)
and (p, pn) Cross Sections from Neutron-Rich Nuclei,” Phys. Rev. Lett. 122, 162503 (2019).
S. Michimasa, J. Hwang, K. Yamada, S. Ota, M. Dozono, N. Imai, K. Yoshida, Y. Yanagisawa, K. Kusaka, M. Ohtake, M. Matsushita,
D. S. Ahn, O. Beliuskina, N. Chiga, K. Chikaato, N. Fukuda, S. Hayakawa, E. Ideguchi, K. Iribe, C. Iwamoto, S. Kawase, K. Kawata,
N. Kitamura, S. Masuoka, H. Miyatake, D. Nagae, R. Nakajima, T. Nakamura, K. Nakano, S. Omika, H. Otsu, H. Sakurai, P. Schrock,H. Shimizu, Y. Shimizu, T. Sumikama, X. Sun, D. Suzuki, H. Suzuki, M. Takaki, M. Takechi, H. Takeda, S. Takeuchi, T. Teranishi,
R. Tsunoda, H. Wang, Y. Watanabe, Y. X. Watanabe, K. Wimmer, K. Yako, H. Yamaguchi, L. Yang, H. Yoshida, and S. Shimoura,“OEDO, the energy-degrading beamline at RI Beam Factory,” Prog. Theor. Exp. Phys. 2019, 043D01 (2019).
J. Hwang, S. Michimasa, S. Ota, M. Dozono, N. Imai, K. Yoshida, Y. Yanagisawa, K. Kusaka, M. Ohtake, D. S. Ahn, O. Beliuskina,
N. Fukuda, C. Iwamoto, S. Kawase, K. Kawata, N. Kitamura, S. Masuoka, H. Otsu, H. Sakurai, P. Schrock, T. Sumikama, H. Suzuki,
M. Takaki, H. Takeda, R. Tsunoda, K. Wimmer, K. Yako, and S. Shimoura, “Angle-tunable wedge degrader for an energy-degrading
RI beamline,” Prog. Theor. Exp. Phys. 2019, 043D02 (2019).
S. Takeuchi, T. Nakamura, M. Shikata, Y. Togano, Y. Kondo, J. Tsubota, T. Ozaki, A. Saito, H. Otsu, H. Wang, H. Sakurai, Y. Watanabe,
S. Kawase, D. S. Ahn, M. Aikawa, T. Ando, S. Araki, S. Chen, N. Chiga, P. Doornenbal, S. Ebata, N. Fukuda, T. Isobe, S. Kawakami,
T. Kin, S. Koyama, S. Kubono, Y. Maeda, A. Makinaga, M. Matsushita, T. Matsuzaki, S. Michimasa, S. Momiyama, S. Nagamine,
K. Nakano, M. Niikura, K. Ogata, T. Saito, Y. Shiga, Y. Shimizu, S. Shimoura, T. Sumikama, P. A. Söderström, H. Suzuki, H. Takeda,
R. Taniuchi, M. Uesaka, Y. Watanabe, K. Wimmer, T. Yamamoto, and K. Yoshida, “Coulomb breakup reactions of 93, 94 Zr in inverse
kinematics,” Prog. Theor. Exp. Phys. 2019, 013D02 (2019).

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Z. Elekes, A. Kripko, D. Sohler, K. Sieja, K. Ogata, K. Yoshida, P. Doornenbal, A. Obertelli, G. Authelet, H. Baba, D. Calvet, F. Chateau,
A. Corsi, A. Delbart, J. -M. Gheller, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, H. Otsu,
C. Peron, A. Peyaud, E. C. Pollacco, J. -Y. Rousse, H. Sakurai, C. Santamaria, Y. Shiga, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang,
K. Yoneda, F. Browne, L. X. Chung, Zs. Dombradi, F. Flavigny, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadynska-Klek, Z. Korkulu,
S. Koyama, Y. Kubota, J. Lee, M. Lettmann, C. Louchart, R. Lozeva, K. Matsui, T. Miyazaki, M. Niikura, S. Nishimura, L. Olivier,S. Ota, Z. Patel, E. Sahin, C. Shand, P. -A. Söderström, I. Stefan, D. Steppenbeck, T. Sumikama, D. Suzuki, Zs. Vajta, V. Werner, J. Wu,
and Z. Xu, “Nuclear structure of 76 Ni from the (p,2p) reaction,” Phys. Rev. C 99, 014312 (2019).
S. Chen, J. Lee, P. Doornenbal, A. Obertelli, C. Barbieri, Y. Chazono, P. Navratil, K. Ogata, T. Otsuka, F. Raimondi, V. Soma, Y. Utsuno,
K. Yoshida, H. Baba, F. Browne, D. Calvet, F. Chateau, N. Chiga, A. Corsi, M. L. Cortes, A. Delbart, J. M. Gheller, A. Giganon,
A. Gillibert, C. Hilaire, T. Isobe, J. Kahlbow, T. Kobayashi, Y. Kubota, V. Lapoux, H. N. Liu, T. Motobayashi, I. Murray, H. Otsu,
V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun, Y. Togano, T. Uesaka, K. Wimmer,
K. Yoneda, N. Achouri, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R. -B. Gerst, J. Gibelin, K. I. Hahn,
D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, C. Lehr, B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Y. Park,D. Rossi, E. Sahin, D. Sohler, P. A. Söderström, S. Takeuchi, H. Tornqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu,
H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti, “Quasifree neutron knockout from 54 Ca corroborates arising N = 34 neutron
magic number,” Phys. Rev. Lett. 123, 142501 (2019).
L. Stuhl, M. Sasano, J. Gao, Y. Hirai, K. Yako, T. Wakasa, D. S. Ahn, H. Baba, A. I. Chilug, S. Franchoo, Y. Fujino, N. Fukuda, J. Gibelin,
I. S. Hahn, Z. Halasz, T. Harada, M. N. Harakeh, D. Inomoto, T. Isobe, H. Kasahara, D. Kim, G. G. Kiss, T. Kobayashi, Y. Kondo,
Z. Korkulu, S. Koyama, Y. Kubota, A. Kurihara, H. N. Liu, M. Matsumoto, S. Michimasa, H. Miki, M. Miwa, T. Motobayashi,
T. Nakamura, M. Nishimura, H. Otsu, V. Panin, S. Park, A. T. Saito, H. Sakai, H. Sato, T. Shimada, Y. Shimizu, S. Shimoura,
A. Spiridon, I. C. Stefanescu, X. Sun, Y. L. Sun, H. Suzuki, E. Takada, Y. Togano, T. Tomai, L. Trache, D. Tudor, T. Uesaka, H. Yamada,Z. Yang, M. Yasuda, K. Yoneda, K. Yoshida, J. Zenihiro, and N. Zhang, “Study of spin-isospin responses of radioactive nuclei with thebackground-free neutron spectrometer, PANDORA,” Nucl. Instrum. Methods Phys. Res. B 463, 189–194 (2020).
S. Michimasa, N. Imai, M. Dozono, J. W. Hwang, K. Yamada, S. Ota, K. Yoshida, Y. Yanagisawa, K. Kusaka, M. Ohtake, M. Matsushita,
D. S. Ahn, O. Beliuskina, N. Chiga, K. Chikaato, N. Fukuda, S. Hayakawa, E. Ideguchi, K. Iribe, C. Iwamoto, S. Kawase, K. Kawata,
N. Kitamura, S. Masuoka, H. Miyatake, D. Nagae, R. Nakajima, T. Nakamura, K. Nakano, S. Omika, H. Otsu, H. Sakurai, P. Schrock,H. Shimizu, Y. Shimizu, T. Sumikama, X. Sun, D. Suzuki, H. Suzuki, M. Takaki, M. Takechi, H. Takeda, S. Takeuchi, T. Teranishi,
R. Tsunoda, H. Wang, Y. Watanabe, Y. X. Watanabe, K. Wimmer, K. Yako, H. Yamaguchi, L. Yang, H. Yoshida, and S. Shimoura,“New energy-degrading beamline for in-flight RI beams, OEDO,” Nucl. Instrum. Methods Phys. Res. B 463, 143 (2020).
M. L. Cortés, W. Rodriguez, P. Doornenbal, A. Obertelli, J. D. Holt, S. M. Lenzi, J. Menéndez, F. Nowacki, K. Ogata, A. Poves,
T. R. Rodrguez, A. Schwenk, J. Simonis, S. R. Stroberg, K. Yoshida, L. Achouri, H. Baba, F. Browne, D. Calvet, F. Chateau, S. Chen,
N. Chiga, A. Corsi, A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux,
H. N. Liu, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun,
Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R. -B. Gerst,
J. Gibelin, K. I. Hahn, D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B. D. Linh, T. Lokotko, M. MacCormick,
K. Moschner, T. Nakamura, S. Y. Park, D. Rossi, E. Sahin, D. Sohler, P. -A. Söderström, S. Takeuchi, H. Toernqvist, V. Vaquero,
V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti, “Shell evolution of N = 40 isotones
towards 60 Ca; First spectroscopy of 62 Ti,” Phys. Lett. B 800, 135071 (2020).
A. E. Barzakh, D. Atanasov, A. N. Andreyev, M. Al Monthery, N. A. Althubiti, B. Andel, S. Antalic, K. Blaum, T. E. Cocolios, J. G. Cubiss, P. Van Duppen, T. Day Goodacre, A. de Roubin, Yu. A. Demidov, G. J. Farooq-Smith, D. V. Fedorov, V. N. Fedosseev, D. A. Fink,
L. P. Gaﬀney, L. Ghys, R. D. Harding, D. T. Joss, F. Herfurth, M. Huyse, N. Imai, M. G. Kozlov, S. Kreim, D. Lunney, K. M. Lynch,
V. Manea, B. A. Marsh, Y. Martinez Palenzuela, P. L. Molkanov, D. Neidherr, R. D. Page, M. Rosenbusch, R. E. Rossel, S. Rothe,
L. Schweikhard, M. D. Seliverstov, S. Sels, C. Van Beveren, E. Verstraelen, A. Welker, F. Wienholtz, R. N. Wolf, and K. Zuber,“Hyperfine anomaly in gold and magnetic moments of I π = 11/2− gold isomers,” Phys. Rev. C 101, 034308 (2020).
K. B. Howard, U. Garg, M. Itoh, H. Akimune, S. Bagchi, T. Doi, Y. Fujikawa, M. Fujiwara, T. Furuno, M. N. Harakeh, Y. Hijikata,
K. Inaba, S. Ishida, N. Kalantar-Nayestanaki, T. Kawabata, S. Kawashima, K. Kitamura, N. Kobayashi, Y. Matsuda, A. Nakagawa,S. Nakamura, K. Nosaka, S. Okamoto, S. Ota, S. Weyhmiller, and Z. Yang, “Compression-mode resonances in the calcium isotopes
and implications for the asymmetry term in nuclear incompressibility,” Phys. Lett. B 801 135185 (2020).
T. Lokotko, S. Leblond, J. Lee, P. Doornenbal, A. Obertelli, A. Poves, F. Nowacki, K. Ogata, K. Yoshida, G. Authelet, H. Baba, D. Calvet,
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L. Kaya, A. Vogt, P. Reiter, M. Siciliano, N. Shimizu, Y. Utsuno, H. -K. Wang, A. Gargano, L. Coraggio, N. Itaco, K. Arnswald,
D. Bazzacco, B. Birkenbach, A. Blazhev, A. Bracco, B. Bruyneel, L. Corradi, F. C. L. Crespi, G. de Angelis, M. Droste, J. Eberth,A. Esmaylzadeh, E. Farnea, E. Fioretto, C. Fransen, A. Gadea, A. Giaz, A. Görgen, A. Gottardo, K. Hadyńska-Klȩk, H. Hess, R. Hirsch,P. R. John, J. Jolie, A. Jungclaus, V. Karayonchev, L. Kornwebel, W. Korten, S. Leoni, L. Lewandowski, S. Lunardi, R. Menegazzo,
D. Mengoni, C. Michelagnoli, T. Mijatović, G. Montagnoli, D. Montanari, C. Müller-Gatermann, D. Napoli, Zs. Podolyák, G. Pollarolo, F. Recchia, J. -M. Régis, N. Saed-Samii, E. Şahin, F. Scarlassara, K. Schomacker, M. Seidlitz, B. Siebeck, P. -A. Söderström,
A. M. Stefanini, O. Stezowski, S. Szilner, B. Szpak, E. Teruya, C. Ur, J. J. Valiente-Dobón, K. Wolf, K. Yanase, N. Yoshinaga, andK. O. Zell, “Isomer spectroscopy in 133 Ba and high-spin structure of 134 Ba,” Phys. Rev. C 100, 024323 (2019).
T. Miyagi, T. Abe, M. Kohno, P. Navrátil, R. Okamoto, T. Otsuka, N. Shimizu, and S. R. Stroberg, “Ground-state properties of doubly
magic nuclei from the unitary-model-operator approach with chiral two- and three-nucleon forces,” Phys. Rev. C 100, 034310 (2019).
Md. S. R. Laskar, R. Palit, S. N. Mishra, N. Shimizu, Y. Utsuno, E. Ideguchi, U. Garg, S. Biswas, F. S. Babra, R. Gala, C. S. Palshetkar,
and Z. Naik, “Structure of the 11/2- isomeric state in 133 La,” Phys. Rev. C 101, 034315 (2020).
M. Hoferichter, P. Klos, J. Menéndez, and A. Schwenk, “Nuclear structure factors for general spin-independent WIMP-nucleus scattering,”
Phys. Rev. D 99, 055031 (2019).
L. W. Iskra, R. Broda, R. V. F. Janssens, M. P. Carpenter, B. Fornal, T. Lauritsen, T. Otsuka, T. Togashi, Y. Tsunoda, W. B. Walters, andS. Zhu, “Revised B(E3) transition rate and structure of the 3− level in 96 Zr,” Phys. Lett. B 788, 396 (2019).
L. Xie, X. F. Yang, C. Wraith, C. Babcock, J. Bieroń, J. Billowes, M. L. Bissell, K. Blaum, B. Cheal, L. Filippin, K. T. Flanagan,
R. F. Garcia Ruiz, W. Gins, G. Gaigalas, M. Godefroid, C. Gorgesk, L. K. Grob, H. Heylen, P. Jönsson, S. Kaufman. M. Kowalska,
J. Krämer, S. Malbrunot-Ettenauer, R. Neugart, G. Neyens, W. Nörtershäuser, T. Otsuka, J. Papuga, R. Sánchez, Y. Tsunoda, and
D. T. Yordanov, “Nuclear charge radii of 62–80 Zn and their dependence on cross-shell proton excitations,” Phys. Lett. B 797, 134805(2019).
E. A. Coello Perez, J. Menéndez, and A. Schwenk, “Two-neutrino double electron capture on 124 Xe based on an eﬀective theory and thenuclear shell model,” Phys. Lett. B 797, 134885 (2019).
C. Hornung, D. Amanbayev, I. Dedes, G. Kripko-Koncz, I. Miskun, N. Shimizu, S. A. S. Andres, J. Bergmann, T. Dickel, J. Dudek,
J. Ebert, H. Geissel, M. Gorska, H. Grawe, F. Greiner, E. Haettner, T. Otsuka, W. R. Plass, S. Purushothaman, A. -K. Rink, C. Scheidenberger, H. Weick, S. Bagchi, A. Blazhev, O. Charviakova, D. Curien, A. Finlay, S. Kaur,W. Lippert, J. -H. Otto, Z. Patyk, S. Pietri,
Y. K. Tanaka, Y. Tsunoda, and J. S. Winfield, “Isomer studies in the vicinity of the doubly-magic nucleus 100 Sn; observation of a new
low-lying isomeric state in 97 Ag,” Phys. Lett B 802, 135200 (2020).

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Y. L. Sun, A. Obertelli, P. Doornenbal, C. Barbieri, Y. Chazono, T. Duguet, H. N. Liu, P. Navrátil, F. Nowacki, K. Ogata, T. Otsuka,
F. Raimondid, V. Somà, Y. Utsuno, K. Yoshida, N. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chenq, N. Chiga, A. Corsi,
M. L. Cortés, A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. Togano, T. Uesaka,
K. Wimmer. K. Yoneda, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gašparić, R. -B. Gerst, J. Gibelin, K. I. Hahna,
D. Kima, T. Koiwai, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B. D. Linh, T. Lokotko, M. Ma, Cormick, K. Moschner, T. Nakamura,
S. Y. Park, D. Rossi, E. Sahin, D. Sohler, P. -A. Söderström, S. Takeuchi, H. Törnqvista, V. Vaquero, V. Wagner, S. Wang, V. Werner,
X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti, “Restoration of the natural E(1/2+1)-E(3/2+1) energy splitting in
Odd-K isotopes towards N = 40,” Phys. Lett. B 802, 135215 (2020).
N. Shimizu, T. Mizusaki, Y. Utsuno, and Y. Tsunoda, “Thick-restart block Lanczos method for large-scale shell-model calculations,”
Comp. Phys. Comm. 244, 372 (2019).
M. L. Cortés, W. Rodriguez, P. Doornenbal, A. Obertelli, J. D. Holt, S. M. Lenzi, J. Menéndez, F. Nowacki, K. Ogata, A. Poves,
T. R. Rodrı́guez, A. Schwenk, J. Simonis, S. R. Stroberg, K. Yoshida, L. Achouri, H. Baba, F. Browne, D. Calvet, F. Château,jS. Chens, N. Chiga, A. Corsi, A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota,
V. Lapoux. H. N. Liu, T. Motobayashi. I. Murray, H. Otsu, V. Panin. N. Paul, H. Sakurai. M. Sasano, D. Steppenbeck, L. Stuhl,
Y. L. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gašparić, R. B. Gerst, J. Gibelin, K. I. Hahn, D. Kima, T. Koiwai, Y. Kondo, P. Koseogloue, J. Lee, C. Lehr B. D. Linh, T. Lokotko. M. MacCormick,
K. Moschner. T. Nakamura, S. Y. Park, D. Rossi, E. Sahin, D. Sohler, P. -A. Söderström, S. Takeuchi, H. Toernqviste, V. Vaqueroa,
V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan. Z. Yang, M. Yasuda, and L. Zanetti, “Shell evolution of N = 40 isotones
towards 60 Ca; First spectroscopy of 62 Ti,” Phys. Lett. B 800, 135071 (2020).
V. Manea, J. Karthein, D. Atanasov, M. Bender, K. Blaum, T. E. Cocolios, S. Eliseev, A. Herlert, J. D. Holt, W. J. Huang, Yu. A. Litvinov,
D. Lunney, J. Menéndez, M. Mougeot, D. Neidherr, L. Schweikhard, A. Schwenk, J. Simonis, A. Welker, F. Wienholtz, and K. Zuber,First glimpse of the N = 82 shell closure below Z = 50 from masses of neutron-rich cadmium isotopes and isomers, Phys. Rev. Lett.
124, 092502 (2020).
M. Ciemala, S. Ziliani, F. C. L. Crespi, S. Leoni, B. Fornal, A. Maj, P. Bednarczyk, G. Benzoni, A. Bracco, C. Boiano, S. Bottoni,
S. Brambilla, M. Bast, M. Beckers, T. Braunroth, F. Camera, N. Cieplicka-Orynczak, E. Clement, S. Coelli, O. Dorvaux, S. Erturk,
G. de France, C. Fransen, A. Goldkuhle, J. Grebosz, M. N. Harakeh, L. W. Iskra, B. Jacquot, A. Karpov, M. Kicinska-Habior, Y. Kim,
M. Kmiecik, A. Lemasson, S. M. Lenzi, M. Lewitowicz, H. Li, I. Matea, K. Mazurek, C. Michelagnoli, M. Matejska-Minda, B. Million,
C. Muller-Gatermann, V. Nanal, P. Napiorkowski, D. R. Napoli, R. Palit, M. Rejmund, Ch. Schmitt, M. Stanoiu, I. Stefan, E. Vardaci,
B. Wasilewska, O. Wieland, M. Zieblinski, M. Zielinska, A. Atac, D. Barrientos, B. Birkenbach, A. J. Boston, B. Cederwall, L. Charles,
J. Collado, D. M. Cullen, P. Desesquelles, C. Domingo-Pardo, J. Dudouet, J. Eberth, V. Gonzalez, J. Goupil, L. J. Harkness-Brennan,
H. Hess, D. S. Judson, A. Jungclaus, W. Korten, M. Labiche, A. Lefevre, R. Menegazzo, D. Mengoni, J. Nyberg, R. M. Perez-Vidal,
Zs. Podolyak, A. Pullia, F. Recchia, P. Reiter, F. Saillant, M. D. Salsac, E. Sanchis, O. Stezowski, Ch. Theisen, J. J. Valiente-Dobon,
J. D. Holt, J. Menéndez, A. Schwenk, and J. Simonis, “Lifetime measurements of the second 2+ state in neutron-rich 16 C and 20 O as atest of ab initio nuclear structure, Phys. Rev. C 101 021303 (2020).
֯ా༎հ, “Ni ಉҐମʹ͓͚Δ৽‫ͳح‬ม‫ڞܗ‬ଘ‫ݱ‬৅ͱ֩ࢠ഑Ґʹґଘ֪ͨ͠ਐԽͷ‫ڀݚ‬,” ‫ڀݚ֩ࢠݪ‬ୈ 64 ‫ ר‬1 ߸ 25 ท (2019).

[Books]T. Shibata, I. Tanihata, M. Fujiwara, T. Otsuka, and S. Shimoura: “Large-scale investigation of deposited radioactive materials,” Environmental Contamination from the Fukushima Nuclear Disaster, ed., Teruyuki Nakajima, Toshimasa Ohara, Mitsuo Uematsu and Yuichi
Onda, CAMBRIDGE ENVIRONMENTAL CHEMISTRY SERIES, CAMBRIDGE, 2019, pp. 309–323.

[Proceedings]
S. Hayakawa, K. Abe, O. Beliuskina, S. M. Cha, K. Y. Chae, S. Cherubini, P. Figuera, Z. Ge, M. Gulino, J. Hu, A. Inoue, N. Iwasa,
D. Kahl, A. Kim, D. H. Kim, G. G. Kiss, S. Kubono, M. La Cognata, M. La Commara, L. Lamia, M. Lattuada, E. J. Lee, J. Y. Moon,
S. Palmerini, C. Parascandolo, S. Y. Park, D. Pierroutsakou, R. G. Pizzone, G. G. Rapisarda, S. Romano, H. Shimizu, C. Spitaleri,
X. Tang, O. Trippella, A. Tumino, P. Vi, H. Yamaguchi, L. Yang, and N. T. Zhang, “Cross section measurements of the 7 Be(n, p)7 Li
and the 7 Be(n, α)4 He reactions covering the Big-bang nucleosynthesis energy range by the Trojan horse method at CRIB,” Nuclei in
the Cosmos XV (Springer International Publishing), 33–37 (2019).
H. Yamaguchi, S. Hayakawa, L. Yang, H. Shimizu, D. Kahl, and CRIB collaboration, “Study on explosive nucleosynthesis with lowenergy RI beams at CRIB,” Nuclei in the Cosmos XV (Springer International Publishing), 265–268 (2019).
L. Lamia, C. Spitaleri, M. Mazzocco, S. Hayakawa, C. A. Bertulani, A. Boiano, C. Boiano, C. Broggini, A. Caciolli, R. Depalo, F. Galtarossa, G. L. Guardo, M. Gulino, S. Kubono, M. La Cognata, M. La Commara, G. La Rana, M. Lattuada, R. Menegazzo, A. Pakou,
C. Parascandolo, D. Piatti, D. Pierroutsakou, R. G. Pizzone, S. Romano, G. G. Rapisarda, M. L. Sergi, O. Sgouros, F. Soramel, V. Soukeras, E. Strano, D. Torresi, A. Tumino, H. Yamaguchi, F. L. Villante, and G. L. Zhang, “The cosmologically relevant 7 Be(n, α)4 Hereaction in view of the recent THM investigations,” Nuclei in the Cosmos XV (Springer International Publishing), 53–56 (2019).
A. A. Oliva, L. Lamia, G. L. Guardo, C. Spitaleri, S. Cherubini, A. Cvetinovic, G. D’Agata, N. de Sereville, A. Di Pietro, P. Figuera,
M. Gulino, F. Hammache, S. Hayakawa, I. Indelicato, M. La Cognata, M. La Commara, D. Lattuada, M. Lattuada, G. Manicò,
M. Mazzocco, S. Messina, S. Palmerini, R. G. Pizzone, M. L. Pumo, G. G. Rapisarda, S. Romano, M. L. Sergi, N. Soic, R. Spartà, and
A. Tumino, “Study of the neutron induced reaction 17 O(n, α)14 C at astrophysical energies via the Trojan Horse Method,” EPJ Web ofConferences 227, 02007 (2020).
R. G. Pizzone, G. D’Agata, I. Indelicato, M. L. Cognata, P. Figuera, G. L. Guardo, S. Hayakawa, L. Lamia, M. Lattuada, M. Milin,
G. G. Rapisarda, S. Romano, M. L. Sergi, N. Skukan, N. Soic, C. Spitaleri, and A. Tumino, “Fluorine destruction in stars studied via
Trojan horse method,” Proceedings of the 15th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG15),- 408 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

JPS Conf. Proc. 31, 011002 (2020).
S. Ishikawa, N. Iwasa, S. Kubono, K. Asada, D. Guru, S. Hayakawa, K. Hirose, T. Kawabata, K. Kominato, H. Makii, M. Matsuda,
S. Nishimura, K. Nishio, R. Orlandi, and T. Sakakibara, “Experimental study of the 7 Be(n, p1)7 Li* reaction for the cosmologicallithium problem,” Proceedings of the 15th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG15), JPS
Conf. Proc. 31, 011037 (2020).
S. Palmerini, M. L. Cognata, L. Acosta, R. Alba, E. Chavez, S. Cherubini, G. D. Agata, A. D. Pietro, P. Figuera, K. D. L. Rios,
G. L. Guardo, M. Gulino, S. Hayakawa, G. Kiss, M. L. Commara, L. Lamia, C. Maiolino, G. Manico, M. Mazzocco, J. Mrazek,
C. Parascandalo, T. Petruze, D. Pierroutsakou, R. Pizzone, G. Rapisarda, S. Romano, D. Santonocito, R. Sparta, C. Spitaleri, and
A. Tumino, “Measurement of the 27 Al(p, α)24 Mg reaction at astrophysical energies via the Trojan horse method,” Proceedings of the
15th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG15), JPS Conf. Proc. 31, 011056 (2020).
S. Hayakawa, M. L. Cognata, L. Lamia, H. Shimizu, L. Yang, H. Yamaguchi, K. Abe, O. Beliuskina, S. M. Cha, K. Y. Chae, S. Cherubini,
P. Figuera, Z. Ge, M. Gulino, J. Hu, A. Inoue, N. Iwasa, D. Kahl, A. Kim, D. H. Kim, G. Kiss, S. Kubono, M. L. Commara, M. Lattuada,
E. J. Lee, J. Y. Moon, S. Palmerini, C. Parascandolo, S. Y. Park, D. Pierroutsakou, R. G. Pizzone, G. G. Rapisarda, S. Romano,
C. Spitaleri, X. D. Tang, O. Trippella, A. Tumino, P. Vi, and N. T. Zhang, “Experimental study on the 7 Be(n, p)7 Li and the 7 Be(n, α)4 Hereactions for cosmological lithium problem,” Proceedings of the 15th International Symposium on Origin of Matter and Evolution of
Galaxies (OMEG15), JPS Conf. Proc. 31, 011036 (2020).
H. Shimizu, D. Kahl, H. Yamaguchi, K. Abe, O. Beliuskina, S. M. Cha, K. Y. Chae, A. A. Chen, Z. Ge, S. Hayakawa, N. Imai, N. Iwasa,
A. Kim, D. H. Kim, M. J. Kim, S. Kubono, M. S. Kawag, J. Liang, J. Y. Moon, S. Nishimura, S. Oka, S. Y. Park, A. Psaltis, T. Teranishi,
Y. Ueno, and L. Yang, “Study on 26m Al(p, γ), reaction at the SNe temperature,” Proceedings of the 15th International Symposium on
Origin of Matter and Evolution of Galaxies (OMEG15), JPS Conf. Proc. 31, 011073 (2020).
L. Yang, C. Lin, H. Jia, N. Ma, D. Wang, F. Yang, L. Sun, X. Xu, P. Wen, and F. Zhong, “Reactions with exotic nuclei at near andsub-barrier energies,” EPJ Web of Conferences 223, 01071 (2019).
A. Uchiyama, K. Harada, T. Inoue, H. Kawamura, K. S. Tanaka, M. Itoh, T. Aoki, A. Hatakeyama, Y. Takahashi and Y. Sakemi, “Development of a dual isotope co-magnetometer using laser cooled rubidium toward electron electric dipole moment measurement using
Francium,” Journal of Physics: Conf. Series 1206, 012008 (2019).
M. Hoferichter, P. Klos, J. Menéndez, and A. Schwenk, “Dark-matter-nucleus scattering in chiral eﬀective field theory,” Proceedings of
the 9th International Workshop on Chiral Dynamics, PoS CD2018 (2019) 095.

Presentations[International conferences/workshops]
N. Imai (Oral), “Single particle structure coupled to the second 0+ state in 32Mg,” High resolution gamma ray spectroscopy at RIBF,
T. U. Darmstadt, Germany, April 10–12, 2019.
N. Imai (Invited), “Controlling the motions of two kinds of fermions in a nucleus, a new energy degraded RI beam line OEDO,” Frontier
Session of KPS meeting, Deajon, Korea, April 24–26, 2019.
N. Imai (Oral), “Evaluation of the neutron capture reaction on 79 Se via a surrogate reaction of d(79 Se, p) reaction at OEDO,” The 15th
International Symposium on Origin of Matter and Evolution of Galaxies, Kyoto, July 2–5, 2019.
S. Michimasa (Oral), “Closed-shell nature in neutrons of 54 Ca,” International Nuclear Physics Conference 2019 (INPC2019), Scottish
Event Campus, Glasgow, UK, July 29–August 2, 2019.
M. Dozono (Oral), “Proton-induced reactions on 107 Pd at around 30 MeV/nucleon: First result using slowed-down RI beams at OEDO,”
International Nuclear Physics Conference 2019 (INPC2019), Scottish Event Campus, Glasgow, UK, July 29–August 2, 2019.
J. Hwang (Oral), “Performance of the OEDO beamline,” International Nuclear Physics Conference 2019 (INPC2019), Scottish Event
Campus, Glasgow, UK, July 29–August 2, 2019.
N. Kitamura (Oral), “Structure of 30 Mg studied by in-beam gamma-ray spectroscopy via neutron knockout reactions,” International
Nuclear Physics Conference 2019 (INPC2019), Scottish Event Campus, Glasgow, UK, July 29–August 2, 2019.
N. Kitamura (Oral), “High-resolution spectroscopy of 95–98 Kr,” 8th SUNFLOWER Workshop / HiCARI Workshop, Osaka University,
Osaka, Japan, August 26–28, 2019.
S. Michimasa (Invited), “OEDO status report and development,” OEDO collaboration meeting 2019, Nishina, Saitama, Japan, September
2, 2019.
N. Imai (Invited), “Status report of ImPACT17-02-02,” OEDO collaboration meeting 2019, Nishina, Saitama, Japan, September 2, 2019.
M. Dozono (Invited), “Status report of ImPACT17-02-01,” OEDO collaboration meeting 2019, Nishina, Saitama, Japan, September 2,
2019.
J. Hwang (Invited), “Study of octupole deformation at OEDO,” OEDO collaboration meeting 2019, Nishina, Saitama, Japan, September
2, 2019.
N. Imai (Invited), “Proposal of he surrogate reaction of 130 Sn(n, γ),” OEDO collaboration meeting 2019, Nishina, Saitama, Japan, September 2, 2019.
S. Shimoura (Invited), “OEDO project—Slowing-down beam line in RIKEN RIBF,” XXIII International School on Nuclear Physics andApplication (Varna2019), Varna, Bulgaria, September 23–27, 2019.
S. Michimasa (Invited), “Present status of the OEDO-SHARAQ system,” Expert Meeting on Next-Generation Fragment Separators
2019, GSI, Germany, September 30–October 2, 2019.
S. Shimoura (Invited), “Slowing-down beam line in RIKEN RIBF—OEDO,” 14th Asia-Pacific Physics Conference (APPC2019), Kuching, Malaysia, November 17–22, 2019.

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S. Michimasa (Oral), “Experimental study of neutron shell gap in Calcium-54,” 14th Asia-Pacific Physics Conference (APPC2019),
Kuching, Malaysia, November 17–22, 2019.
S. Ota (Oral), “Research of isoscalar giant monopole resonances using gaseous activetarget,” 14th Asia-Pacific Physics Conference(APPC2019), Kuching, Malaysia, November 17–22, 2019.
N. Imai (Invited), “Shape coexistence of atomic nuclei,” Frontier Session of KPS meeting, KDJ Center, Gwangju, Korea, December
23–25, 2019.
M. Dozono (Invited), “Nuclear astrophysics studies with OEDO,” JSPS/NRF/NSFC A3 Foresight Program “Nuclear Physics in the 21stCentury” Joint Kickoﬀ Meeting, Kobe, Hyogo, Japan, December 6–7, 2019.
S. Ota (invited), “Kτ from ISGMR measurements on and around 132 Sn,” Gordon Research Conference, Nuclear Chemistry, “Exploring
simple structure patterns and the dynamics of nuclei,” New London, NH, US, June 16–21, 2019.
S. Ota (oral), “Giant resonances in Tin-region nuclei studied using gaseous active target,” Vth Topical Workshop on Modern Aspects inNuclear Structure, Bormio, Italy, February 04–09, 2020.
H. Yamaguchi (invited), “Studying astrophysical reactions and nuclear clusters with low-energy RI beams,” 2019 KPS Spring Meeting,Pioneering session: Low energy nuclear science for astrophysics, Daejeon, Korea, April 25, 2019.
H. Yamaguchi (invited), “Experiments on astrophysical reactions with low-energy unstable nuclei beams at CRIB,” The 27th International
Nuclear Physics Conference (INPC 2019), Glasgow, U.K., July 29–August 2, 2019.
H. Yamaguchi (invited), “Nuclear astrophysics with low-energy RI beams,” Nuclear Physics School for Young Scientists (NUSYS-2019),
Lanzhou, China, August 12–17, 2019.
H. Shimizu (poster), “Isomeric 26 Al beam production with CRIB,” NUclear physics School for Young Scientists (NUSYS-2019), Lanzhou,
China, August 12–17, 2019.
H. Yamaguchi (oral), “Activities at the low-energy RI beam separator CRIB,” RIBF Users Meeting 2019, Wako, Saitama, Japan, September 3–4, 2019.
H. Yamaguchi (invited), “Nuclear astrophysics projects at CNS, the University of Tokyo,” International workshop on Origin of Elements
and Cosmic Evolution: From Big-Bang to Supernovae and Mergers (OECE), Beijing, China, November 27–29, 2019.
H. Yamaguchi (oral), “Active target for the TTIK method,” Workshop on RI-beam Spectroscopy by Innovative Gaseous Active Targets,
Osaka, Japan, December 19–20, 2019.
S. Hayakawa (invited), “Experimental study on the 7 Be(n, p)7 Li and the 7 Be(n, α)4 He reactions for cosmological lithium problem,” The
15th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG15), Kyoto, Japan, July 2–5, 2019.
H. Shimizu (poster), “Study on 26m Al(p, γ) reaction at the SNe temperature,” The 15th International Symposium on Origin of Matter and
Evolution of Galaxies (OMEG15), Kyoto, Japan, July 2–5, 2019
T. Gunji for the ALICE Collaboration (oral), “Recent results in relativistic heavy-ion collisions with the ALICE experiment at the CERNLHC,” 14th Asia-Pacific Physics Conference (APPC 2019), Kuching, Sarawak, Malaysia, November 17–22, 2019.
D. Sekihata for the ALICE Collaboration (Oral), “Light neutral mesons production at the LHC measured by ALICE,” PHOTON 2019
International Conference on the Structure and the Interactions of the Photon, INFN-LNF, Frascati, Italy, 3–7 June 2019.
D. Sekihata for the ALICE Collaboration (Poster), “Study of dielectron production in Pb-Pb collisions at sqrt(sNN ) = 5.02 TeV with
ALICE,” Quark Matter 2019 - the XXVIIIth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions, Wuhan, China,
November 3–9, 2019.
Y. Sekiguchi for the ALICE collaboration (Oral), “Measurement of long-range two- and multi-particle correlations by ALICE,” theXXVIIIth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions, Wuhan, China, November 3–9, 2019.
Y. Sakemi(invited), “Fundamental physics with cold radioactive atoms,” 14th ASIA-PACIFIC PHYSICS CONFERENCE(APPC14),
Kuching, Malaysia, November 20, 2019.
Y. Sakemi(invited), “Fundamental physics with laser cooled atoms,” 36th Mazurian Lakes Conference on Physics (Probing fundamental
laws of nature with exotic nuclei and atoms), Poland, Piaski, September-2, 2019.
Y. Kotaka (Poster), “Development of the calculation method of injection beam trajectory of RIKEN AVF Cyclotron with 4D emittancemeasured by the developed pepper-pot emittance monitor,” 8th International Beam Instrumentation Conference, Malmö, Sweden,
September 8–12, 2019.
N. Shimizu (invited), “Configuration-interaction shell-model calculations for nuclear structure physics,” 11th Symposium on Discovery,
Fusion, Creation of New Knowledge by Multidisciplinary Computational Sciences, Tsukuba International Congress Center, Tsukuba,
Ibaraki, Japan, October 15, 2019.
N. Shimizu (invited), “Level densities of pf-shell nuclei by large-scale shell-model calculations,” 7th Workshop on Nuclear Level Density
and Gamma Strength, Oslo University, Oslo, Norway, May 28, 2019.
T. Abe (oral), “Alpha-cluster structure of light nuclei from no-core Monte Carlo shell model,” RIBF Users Meeting, RIKEN RIBF,
Saitama, Japan, September 3, 2019.
T. Abe (oral), “Alpha-cluster structure from an ab-initio point of view,” RCNP Workshop on RI-beam Spectroscopy by Innovative Gaseous
Active Targets, RCNP, Osaka University, Osaka, Japan, October 20, 2019.
T. Abe (oral), “Intrinsic structure of light nuclei from no-core Monte Carlo shell model,” Pioneer Symposia on Various Manifestations of
Nuclear Structure, KPS Fall Meeting 2019, Gwangju, Korea, October 20, 2019.
K. Yanase (oral), “CP violation in atomic nuclei and Atomic EDM,” International workshop for graduate students and young physicists
on nuclear physics, Peking, University, Beijing, China, November 22–25, 2019.
K. Yanase (oral), “Atomic EDM and CP violation in atomic nuclei,” Nucleon electric dipole moments and spin structure in 2020, KEK,

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Tokai, Japan, January 11, 2020.
T. Abe (poster), “Alpha-cluster structure from the ab-initio Monte Carlo shell model,” International Symposium on Clustering as a Window
on the Hierarchical Structure of Quantum Systems (CLUSHIQ2020), Ryoutiku Bettei, Oita, Japan, January 23, 2020.
J. Menéndez (invited), “Neutrinoless double-beta decay: novel insights on nuclear matrix elements,” International Nuclear Physics Conference (INPC), Glasgow (United Kingdom), July 2019.
J. Menéndez (invited), “Double-beta decay calculations: new tests and opportunities,” the INT Program “Nuclear Structure at the Crossroads,” Seattle (USA), July 2019
J. Menéndez (invited), “Nuclear physics and double-beta decay,” “Massive Neutrinos,” the Wilhelm und Else Heraeus-Seminar Bad
Honnef (Germany), July 2019.
J. Menéndez (invited), “Relating double-beta decay to nuclear properties at hand,” the workshop “Neutrino Nuclear Responses for Double
Beta Decays and Astro Neutrinos (NNR19),” Osaka (Japan), May 2019.
J. Menéndez (invited), “Beta decay in the nuclear shell model: capabilities, limitations, uncertainties,” ECT*Workshop “Precise beta
decay calculations for searches for new physics,” Trento (Italy)
Y. Tsunoda (poster), “Shapes of Sm isotopes studied by Monte Carlo shell model calculations,” 11th Symposium on Discovery, Fusion,
Creation of New Knowledge by Multidisciplinary Computational Sciences, Tsukuba International Congress Center, Tsukuba, Ibaraki,
Japan, October 15, 2019.

[Domestic conferences/workshops]
N. Imai (Oral), ʮr-process ֩ͷதੑࢠั֫൓Ԡ࣮‫͍ͯͭʹݧ‬ʯ, ‫ڀݚݚج‬ձ “‫֩ࢠݪ‬෺ཧͰ๰͙ r-process” ‫౎ژ‬, 2019 ೥ 5 ݄ 22
೔–24 ೔.
N. Imai (Oral), ʮ‫ٯ‬ӡಈֶ 79 Se(d, p) ൓ԠʹΑΔதੑࢠั֫൓Ԡஅ໘ੵͷධՁʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9
݄ 17 ೔–20 ೔.
K. Kawata (Oral), ʮೖࣹ֩ഁࡅ൓ԠʹΑΔ 52 Fe पล֩ͷߴεϐϯΞΠιϚʔͷੜ੒ʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019
೥ 9 ݄ 17 ೔–20 ೔.
R. Tsunoda (Oral), ʮεζಉҐମͷྭ‫ى‬ঢ়ଶͱ૊ΜͩΞΠιόϦοΫΞφϩά‫ڞ‬໐ঢ়ଶʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬,2019 ೥ 9 ݄ 17 ೔–20 ೔.
N. Kitamura (Oral), ʮΠϯϏʔϜΨϯϚઢ֩෼ޫͰ୳Δ 30 Mg ͷ֩ߏ଄ʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17
೔–20 ೔.
N. Imai (Oral), ʮLow-energy RI beam of versatile element; OEDO at RIBFʯ, ATTPC workshop, େࡕ, 2019 ೥ 12 ݄ 19 ೔–20 ೔.
઒ా‫ܟ‬ଠ΄͔ʢ‫ޱ‬಄ൃදʣ, ʮೖࣹ֩ഁࡅ൓ԠʹΑΔ 52 Fe पล֩ͷߴεϐϯΞΠιϚʔͷੜ੒ʯ, ೔ຊ෺ཧֶձ̎̌̍̕೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17 ೔–20 ೔.
OEDO collaboration meeting 2019, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 9 ݄ 2 ೔.
େా৾ี, ԕ౻ོ࢙ʢ‫ޱ‬಄ൃදʣ, ʮେ‫౓ڧ‬ॏΠΦϯϏʔϜরࣹ༻௿ѹΨεΞΫςΟϒඪత CAT ͷ։ൃͱ‫ݱ‬ঢ়ʯ, ϚΠΫϩύλʔϯΨε‫ݕ‬ग़‫( ث‬MPGD)ɾΞΫςΟϒഔ࣭ TPC ߹ಉ‫ڀݚ‬ձ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 12 ݄ 6–7 ೔.
ԕ౻ོ࢙΄͔ʢ‫ޱ‬಄ൃදʣ, ʮେ‫౓ڧ‬ॏΠΦϯϏʔϜরࣹԼͰͷΞΫςΟϒඪత CAT ʹ͓͚ΔΠΦϯόοΫϑϩʔͷ཈੍ʯ, ೔ຊ෺ཧֶձୈ̓̑ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16 ೔–19 ೔.
ՖҪपଠ࿠΄͔ʢ‫ޱ‬಄ൃදʣ, ʮେ‫ ౓ڧ‬RI ϏʔϜ࣮‫͚͓ʹݧ‬Δߴ଎Ԡ౴ඈ੻‫ݕ‬ग़‫ ث‬SR-PPAC ͷੑೳධՁʯ, ೔ຊ෺ཧֶձୈ̓̑ճ
೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16 ೔–19 ೔.
ಊԂণഢ΄͔ (‫ޱ‬಄ൃද), ʮΞΠιϚʔಉఆͷͨΊͷΞΫςΟϒετούʔͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ,໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16 ೔–19 ೔.
T. Gunji (oral), ʮLHC-ALICE ࣮‫͚͓ʹݧ‬Δ GEM-TPC ߴ౓Խͷ։ൃͱ‫ݱ‬ঢ়ʯ, ୈ 16 ճϚΠΫϩύλʔϯΨε‫ݕ‬ग़‫( ث‬MPGD) ୈ 3
ճΞΫςΟϒഔ࣭ TPC ߹ಉ‫ڀݚ‬ձ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 12 ݄ 6 ೔–7 ೔.
T. Gunji (oral), ʮALICE ࣮‫౓ߴݧ‬Խʹ͓͚Δେ‫ ܕ‬GEM ͱτϦΨʔϨε DAQ ͷ։ൃͱ࣮૷ʯ, ৽ֶज़ྖҬʮΫϥελʔ֊૚ʯʮྔ
ࢠϏʔϜԠ༻ʯ߹ಉ‫ݕ‬ग़‫ث‬ϫʔΫγϣοϓ, ౦๺େֶ, ઋ୆, 2019 ೥ 9 ݄ 20–21 ೔.
T. Gunji (oral), ʮߴΤωϧΪʔॏΠΦϯিಥͷ෺ཧ: ‫ૅج‬ɾ࠷ઌ୺ɾ՝୊ɾల๬ʯ, “কདྷల๬,” ཧ‫ݚ‬γϯϙδ΢Ϝ νϡʔτϦΞϧ‫ڀݚ‬ձ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 8 ݄ 19 ೔–21 ೔.
T. Gunji (oral), ʮFuture ALICE upgrade beyond 2030ʯ, ୈ 36 ճ֦େ൛ Heavy Ion Café, ্ஐେֶ, ઍ୅ా, 2019 ೥ 6 ݄ 22 ೔–23 ೔.
√
D. Sekihata (oral), ʮ֩ࢠର͋ͨΓॏ৺‫ܥ‬ΤωϧΪʔ sNN = 5.02 TeV ཅࢠ-ཅࢠ‫ͼٴ‬Ԗ-Ԗ‫֩ࢠݪ‬িಥʹ͓͚Δதੑதؒࢠͱ௚઀
ޫࢠଌఆʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 17 ೔–20 ೔.
D. Sekihata (Oral), ʮQM2019 Ͱͷϋʔυϓϩʔϒͷ࣮‫ݧ‬త·ͱΊʯ, ʮϙετ QM2019ʯ, ୈ̏̓ճ Heavy Ion Cafe ୈ̏̌ճ Heavy
Ion Pub ߹ಉ‫ڀݚ‬ձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2019 ೥ 12 ݄ 22 ೔.
D. Sekihata (Oral), ʮALICE ࣮‫ ݧ‬TPC ‫ݕ‬ग़‫ث‬ΦϯϥΠϯඈ੻࠶ߏ੒ʹ޲͚ͨ‫ػ‬ցֶशʹΑΔۭؒిՙޮՌͷߴ଎ิਖ਼ʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16 ೔–19 ೔.
ؔ‫ޱ‬༟ࢠ for the ALICE collaboration (Oral), ʮখ͍͞‫͚͓ʹܥ‬Δ௕‫ ཭ڑ‬2 ཻࢠ૬ؔଌఆʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ݄ 16 ೔–19 ೔.
ؔ‫ޱ‬༟ࢠ for the ALICE collaboration (Oral), ʮখ͍͞‫͚͓ʹܥ‬ΔํҐ֯ҟํੑͷϥϐσΟςΟґଘੑʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄.
খߴ߁র (Oral), ʮཧ‫ ݚ‬AVF αΠΫϩτϩϯೖࣹ‫ܥ‬ͷϏʔϜ‫ي‬ಓ‫ํࢉܭ‬๏ͷධՁͱ 4 ࣍‫ݩ‬Τϛολϯεଌఆ‫ث‬ͷվྑʯ, ୈ 16 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ‫౎ژ‬େֶ, ‫౎ژ‬, 2019 ೥ 7 ݄ 31 ೔–8 ݄ 3 ೔.
֯ా༎հʢট଴ߨԋʣ, ʮϞϯςΧϧϩ֪໛‫ʹܕ‬ΑΔϕʔλ่յͷ‫ڀݚ‬ʯ, ‫֩ࢠݪ‬෺ཧͰͭΉ͙ r ϓϩηε, ‫౎ژ‬େֶ‫ૅج‬෺ཧֶ‫ڀݚ‬- 411 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

ॴ, ‫౎ژ‬, 2019 ೥ 5 ݄ 22 ೔.
༄੉޺ଠʢ‫ޱ‬಄ൃදʣ, ʮ‫͚͓ʹ֩ࢠݪ‬Δ CP ରশੑͷഁΕͱి‫ؾ‬૒‫ࢠۃ‬Ϟʔϝϯτʯ, ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬,2019 ೥ 9 ݄ 18 ೔.
ਗ਼ਫଇ޹ʢ‫ޱ‬಄ൃදʣ, ʮ‫࣮ݱ‬త༗ޮ૬‫༻࡞ޓ‬Λ༻͍֪ͨ໛‫ʹܕ‬ΑΔγοϑϞʔϝϯτͷධՁʯ, ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 18 ೔.
֯ా༎հʢ‫ޱ‬಄ൃදʣ, ʮϞϯςΧϧϩ֪໛‫ʹܕ‬ΑΔ Sm ಉҐମͷ‫ܗ‬ঢ়มԽͷ‫ڀݚ‬ʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 18 ೔.
Ѩ෦‫ޱ( ڤ‬಄ൃද), ʮAlpha-cluster structure from the ab-initio Monte Carlo shell modelʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ݄ 18 ೔.
Ѩ෦‫ޱ( ڤ‬಄ൃද), ʮAlpha-cluster structure from ab-initio Monte Carlo shell modelʯ, γϛϡϨʔγϣϯʹΑΔӉ஦ͷ‫ج‬ຊ๏ଇͱਐԽͷղ໌ʹ޲͚ͯ (QUCS 2019), ‫౎ژ‬େֶ‫ૅج‬෺ཧֶ‫ॴڀݚ‬, ‫౎ژ‬, 2019 ೥ 12 ݄ 18 ೔.
֯ా༎հʢ‫ޱ‬಄ൃදʣ, ʮϞϯςΧϧϩ֪໛‫ʹܕ‬ΑΔதॏ֩ͷߏ଄ͷ‫ڀݚ‬ʯ, γϛϡϨʔγϣϯʹΑΔӉ஦ͷ‫ج‬ຊ๏ଇͱਐԽͷղ໌ʹ޲͚ͯ (QUCS 2019), ‫౎ژ‬େֶ‫ૅج‬෺ཧֶ‫ॴڀݚ‬, ‫౎ژ‬, 2019 ೥ 12 ݄ 18 ೔.
ਗ਼ਫଇ޹ʢ‫ޱ‬಄ൃදʣ, ʮ‫֪֩ࢠݪ‬໛‫ͱࢉܭܕ‬ଟ༷ͳม‫ܗ‬όϯυʯ, γϛϡϨʔγϣϯʹΑΔӉ஦ͷ‫ج‬ຊ๏ଇͱਐԽͷղ໌ʹ޲͚ͯ(QUCS 2019), ‫౎ژ‬େֶ‫ૅج‬෺ཧֶ‫ॴڀݚ‬, ‫౎ژ‬, 2019 ೥ 12 ݄ 19 ೔.
༄੉޺ଠʢϙελʔൃදʣ, ʮେ‫ن‬໛֪໛‫ʹࢉܭܕ‬ΑΔ CP ଱༻ੑΛഁΔ૬‫༻࡞ޓ‬ͷ୳ࡧʯ, γϛϡϨʔγϣϯʹΑΔӉ஦ͷ‫ج‬ຊ๏ଇͱਐԽͷղ໌ʹ޲͚ͯ (QUCS 2019), ‫౎ژ‬େֶ‫ૅج‬෺ཧֶ‫ॴڀݚ‬, ‫౎ژ‬, 2019 ೥ 12 ݄ 17 ೔.

[Seminars]
M. N. Harakeh, “Nuclear compression modes from stable to exotic nuclei,” CNS + RIBF NP seminar # 267, RIBF Hall, February 3, 2020.
େ৓޾ޫ (Oral), ʮCNS ΠΦϯ‫ݯ‬ͷ‫ݱ‬ঢ়ʯ, ୈ 17 ճ AVF ߹ಉଧͪ߹Θͤ, ์ࣹઢҩֶ૯߹‫ॴڀݚ‬, ઍ༿, 2019 ೥ 6 ݄ 27 ೔–28 ೔.
খߴ߁র (Oral), ʮཧ‫ ݚ‬AVF ͷ༌ૹ‫࠷ܥ‬దԽͷ‫ݱ‬ঢ়ʯ, ୈ 17 ճ AVF ߹ಉଧͪ߹Θͤ, ์ࣹઢҩֶ૯߹‫ॴڀݚ‬, ઍ༿, 2019 ೥ 6 ݄ 27
೔–28 ೔.
େ৓޾ޫ (Oral), ʮCNS ΠΦϯ‫ݯ‬ͷ‫ݱ‬ঢ়ʯ, ୈ 18 ճ AVF ߹ಉଧͪ߹Θͤ, ཧԽֶ‫ॴڀݚ‬ɾCNS, ࿨ޫ, 2020 ೥ 2 ݄ 18 ೔–19 ೔.
খߴ߁র (Oral), ʮཧ‫ ݚ‬AVF ͷϏʔϜ༌ૹ‫࠷ܥ‬దԽͷ‫ݱ‬ঢ়ʯ, ୈ 18 ճ AVF ߹ಉଧͪ߹Θͤ, ཧԽֶ‫ॴڀݚ‬ɾCNS, ࿨ޫ, 2020 ೥ 2
݄ 18 ೔–19 ೔.
৿Ӭ੖඙ઌੜΛࣱͿձ, ‫ه‬೦ߨԋձʮ̎̍ੈ‫ل‬ͷ෺ཧֶʕӉ஦ɾੜ໋ɾαϒΞτϜʯ, ֶ࢜ձ‫ؗ‬, ઍ୅ా, 2019 ೥ 6 ݄ 2 ೔.

AwardsN. Kitamura, CNSSS18 Young scientist award, ANPhA/AAPPS-DNP award for young scientist for the presentation “characterization ofa tritium target for two-neutron transfer reaction at TRIUMF.”

Others[External review]
External evaluation of CNS, Hongo Campus and CNS Building, January 30–31, 2020.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Partner Institution
Wako Nuclear Science Center, IPNS (Institute of Particle and Nuclear Studies)
KEK (High Energy Accelerator Research Organization)
1. Abstract

The Wako Nuclear Science Center (WNSC) of KEK aims to promote low-energy nuclear physics and nuclear astrophysics research
as well as interdisciplinary studies using short-lived radioactive nuclei. WNSC operates the KEK Isotope Separation System (KISS)
which is an electro-magnetic isotope separator featuring elemental selectivity from the use of resonance laser ionization in a gas
catcher. The KISS facility provides various neutron-rich nuclei via multinucleon transfer reactions. Of particular significance is its
provision of nuclei in the vicinity of the neutron magic number N = 126. Optical and β-γ spectroscopy have been applied to theseneutron-rich nuclear beams, for nuclear structure and nuclear astrophysical studies. Several new developments—a rotating target, adonut-shaped gas cell, and in-jet laser ionization scheme—have been performed to improve the performance of KISS facility. The
WNSC has also developed multi-reflection time of flight mass spectrographs (MRTOF-MS) for precision mass measurements ofshort-lived nuclei in collaboration with the RIKEN SLOWRI team and the Institute of Basic Science (IBS), Korea. After successful
mass measurements in combination with the GARIS-II at RILAC, the existing MRTOF-MS setup has been renewed for use with the
GARIS-II relocated after the ring cyclotron for high precision mass measurements of superheavy nuclides, and additional MRTOF-MS
setups have been placed at KISS and at F11 of the ZeroDegree Spectrometer for comprehensive mass measurements of more than one
thousand nuclides.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Production and manipulation of radioactive isotope beams for nuclear experiments.
Explosive nucleosynthesis (r- and rp-process).
Heavy ion reaction mechanism for producing heavy neutron-rich nuclei.
Development of MRTOF mass spectrographs for short-lived nuclei.
Comprehensive mass measurements of short-lived nuclei including superheavy elements.

3. Summary of Research Activity

The Wako Nuclear Science Center (WNSC) provides low-energy short-lived radioactive ion beams to users from universities
using the KEK isotope separator system (KISS). In FY2019, four experimental programs were carried out at KISS. In terms technicaldevelopments at KISS, an in-jet laser spectroscopy setup for high-precision laser spectroscopy and a multi-reflection time-of-flightmass spectrograph (MRTOF-MS) have been installed and tested online and applied to some physics cases. One was the hyperfine
structure spectroscopy of 194 Os and 196 Os isotopes to determine their isotope shifts. Their half-lives (6 years and 35.9 minutes, respectively) are too long to reasonably determine the resonance wavelengths through decay measurement. However, the mass spectrographallows us to use the ion counting method to identify the resonance by discriminating ions of specific isotope from an isobaric mixture
in the time-of-flight spectrum. Another was β − γ spectroscopy of 192m Os, 192g, 192m Re isotopes of nuclear astrophysical interest. In
this experiment, the KISS beam was shared between the decay station and the MRTOF-MS. During the decay curve measurement at
the decay station, the beam was transferred to the MRTOF-MS to determine the masses and the branching ratios of the isomeric states
and the ground states. The same scheme was also used for the β − γ spectroscopy studies of 186g, 186m, 187g, 197 Ta isotopes.
For the interface between the KISS beams and the MRTOF-MS, a gas cell cooler-buncher (GCCB) plays an essential role. Singlycharged 20 keV ion beams from KISS enter the 30 cm-long gas cell through a 2-mm diameter aperture and are thermalized in 1 mbar
He gas. The thermal ions are extracted by an RF-carpet and transported to a triplet RF quadrupole ion trap before injection into
the MRTOF-MS. We discovered two important phenomena in the GCCB. One is that singly-charged ions are largely converted to
doubly charged ions, which provides a significant gain in the mass resolving power. The other is molecular contaminants in the KISS
beams are totally destroyed in the thermalization process. This feature can be a savior for all low-energy RI-beam facilities whichhave always suﬀered from these molecular contaminations.
In addition to the KISS MRTOF, two more MRTOF setups are presently operated by WNSC in collaboration with RIKENSLOWRI team, one each at the GARIS-II and the BigRIPS facilities of RIKEN RIBF. These will be used for comprehensive massmeasurements of short-lived nuclides including superheavy elements (Z > 103). In FY 2019, the first direct mass measurement ofsuperheavy nuclide (257 Db, Z = 105) has been performed. This setup will be used for precision mass measurements of neutron-rich
moscovium and nihonium isotopes for reliable determination of the atomic numbers as well as the mass numbers. The mass spectrograph at BigRIPS (ZD-MRTOF) is being installed at the end of the BigRIPS+ZeroDegree spectrometer and has already shown ahighest mass resolving power of 570,000 with 9 ms flight time for 39 K+ ions in oﬄine studies. First online commissioning experiment
was scheduled using parasitic beams of in-beam γ experiments in the end of FY2019, however, it was cancelled due to spread of novel
coronavirus disease.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Members
Group Leader
Michiharu WADA
Researchers
Yutaka WATANABEPeter SCHURY
Sunchan Jeong

Yoshikazu HIRAYAMA
Hiroari MIYATAKE
Marco Rosenbusch

Technical Staﬀ
Yutaka KAKIGUCHI

Michihiro OYAIZU

Visiting Researchers
Hermann WOLNICK (NMSU)
Jun-young MOON (IBS)
Sidong CHEN (HKU)
Wenduo XIAN (HKU)
Hiroshi WATANABE (Beihan University)

Hyun-suk CHOI (Seoul National University)
Jiajian LIU (HKU)
Shuxiong YAN (Jinan University)
Dongsheng HOU (IMP)Student Trainees
Toshitaka NIWASE (PhD. Student, Kyushu Univ.)

Shun IIMURA (PhD. Student, Osaka Univ.)

Assistant
Machiko IZAWA

List of Publications & Presentations
Publications[Original papers]
T. Niwase, M. Wada, P. Schury, H. Haba, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Miyatake, K. Morimoto, K. Morita, B. M. Rosenbusch,
H. Wollnik, T. Shanley, and Y. Benari, “Development of an “α-TOF” detector for correlated measurement of atomic masses and decay
properties,” Nucl. Instrum. Methods Phys. Res. A 953, 163198 (2020).
Y. Hirayama, Y. X. Watanabe, M. Mukai, P. Schury, M. Ahmed, H. Ishiyama, S. C. Jeong, Y. Kakiguchi, S. Kimura, J. Y. Moon,
M. Oyaizu, J. H. Park, M. Wada, and H. Miyatake, “Nuclear spectroscopy of r-process nuclei using KEK Isotope Separation System,”Nucl. Instrum. Methods Phys. Res. B 463, 425–430 (2020).
M. Rosenbusch, M. Wada, P. Schury, Y. Ito, H. Ishiyama, S. Ishizawa, Y. Hirayama, S. Kimura, T. M. Kojima, H. Miyatake, J. Y. Moon,
T. Niwase, T. Sonoda, A. Takamine, Y. X. Watanabe, and H. Wollnik, “A new multi-reflection time-of-flight mass spectrograph for the
SLOWRI facility,” Nucl. Instrum. Methods Phys. Res. B 463, 184–188 (2020).
M. Mukai, Y. Hirayama, P. Schury, Y. X. Watanabe, M. Ahmed, H. Haba, H. Ishiyama, S. C. Jeong, Y. Kakiguchi, S. Kimura, J. Y. Moon,
M. Oyaizu, A. Ozawa, J. H. Park, H. Ueno, M. Wada, and H. Miyatake, “Development of a multi-segmented proportional gas counterfor β-decay spectroscopy at KISS,” Nucl. Instrum. Methods Phys. Res. B 463, 421–424 (2020).
P. Schury, M. Wada, H. Wollnik, J. -Y. Moon, T. Hashimoto, and M. Rosenbusch, “High-stability, high-voltage power supplies for use
with multi-reflection time-of-flight mass spectrographs,” Rev. Sci. Instrum. 91, 014702 (2020).
S. Michimasa, N. Imai, M. Dozono, J. W. Hwang, K. Yamada, S. Ota, K. Yoshida, Y. Yanagisawa, K. Kusaka, M. Ohtake, M. Matsushita,
D. S. Ahn, O. Beliuskina, N. Chiga, K. Chikaato, N. Fukuda, S. Hayakawa, E. Ideguchi, and S. Shimoura, “New energy-degrading
beamline for in-flight RI beams, OEDO,” Nucl. Instrum. Methods Phys. Res. B 463, 143–147 (2020).
N. Kimura, R. Kodama, K. Suzuki, S. Oishi, M. Wada, K. Okada, N. Ohmae, H. Katori, and N. Nakamura, “Direct determination of theenergy of the first excited fine-structure level in Ba6+ ,” Phys. Rev. A 100, 052508 (2019).
S. Ahmed, E. Altiere, T. Andalib, M. J. Barnes, B. Bell, C. P. Bidinosti, Y. Bylinsky, J. Chak, M. Das, C. A. Davis, F. Fischer, B. Franke,
M. T. W. Gericke, P. Giampa, M. Hahn, S. Hansen-Romu, K. Hatanaka, T. Hayamizu, B. Jamieson, D. Jones, K. Katsika, S. Kawasaki,
T. Kikawa, W. Klassen, A. Konaka, E. Korkmaz, F. Kuchler, L. Kurchaninov, M. Lang, L. Lee, T. Lindner, K. W. Madison, J. Mammei,
R. Mammei, J. W. Martin, R. Matsumiya, E. Miller, T. Momose, R. Picker, E. Pierre, W. D. Ramsay, Y. -N. Rao, W. R. Rawnsley,
L. Rebenitsch, W. Schreyer, S. Sidhu, S. Vanbergen, W. T. H. van Oers, Y. X. Watanabe, and D. Yosifov, “Fast-switching magnet
serving a spallation-driven ultracold neutron source,” Phys. Rev. Accel. Beams 22, 102401 (2019).
H. Wollnik, M. Wada, P. Schury, M. Rosenbusch, Y. Ito, and H. Miyatake, “Time-of-flight mass spectrographs of high mass resolving
power,” International Journal of Modern Physics A 34, 36, 1942001 (2019).
Y. Hirayama, M. Mukai, Y. X. Watanabe, M. Oyaizu, S. C. Jeong, Y. Kakiguchi, P. Schury, M. Wada, and H. Miyatake, “Eﬃcient twocolor two-step laser ionization schemes of λ1 ∼ 250 nm and λ2 = 307.9 nm for heavy refractory elements-Measurements of ionization
cross-sections and hyperfine spectra of tantalum and tungsten,” Rev. Sci. Instrum. 90, 115104 (2019).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

M. Mazzocco, N. Keeley, A. Boiano, C. Boiano, M. La Commara, C. Manea, C. Parascandolo, D. Pierroutsakou, C. Signorini, E. Strano,
D. Torresi, H. Yamaguchi, D. Kahl, L. Acosta, P. Di Meo, J. P. Fernandez-Garcia, T. Glodariu, J. Grebosz, A. Guglielmetti, Y. Hirayama,
N. Imai, H. Ishiyama, N. Iwasa, S. C. Jeong, H. M. Jia, Y. H. Kim, S. Kimura, S. Kubono, G. La Rana, C. J. Lin, P. Lotti, G. Marquı́nezDurán, I. Martel, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, A. Pakou, K. Rusek, Y. Sakaguchi, A. M. Sánchez-Benı́tez, T. Sava,
O. Sgouros, V. Soukeras, F. Soramel, E. Stiliaris, L. Stroe, T. Teranishi, N. Toniolo, Y. Wakabayashi, Y. X. Watanabe, L. Yang,
Y. Y. Yang, and H. Q. Zhang, “Elastic scattering for the 8 B and 7 Be + 2O8 Pb systems at near-Coulomb barrier energies,” Phys. Rev. C
100, 024602 (2019).
S. Ahmed, T. Andalib, M. J. Barnes, C. B. Bidinosti, Y. Bylinsky, J. Chak, M. Das, C. A. Davis, B. Franke, M. T. W. Gericke, P. Giampa,
M. Hahn, S. Hansen-Romu, K. Hatanaka, B. Jamieson, D. Jones, K. Katsika, S. Kawasaki, W. Klassen, A. Konaka, E. Korkmaz,
F. Kuchler, L. Kurchaninov, M. Lang, L. Lee, T. Lindner, K. W. Madison, J. Mammei, R. Mammei, J. W. Martin, R. Matsumiya,
R. Picker, E. Pierre, W. D. Ramsay, Y. -N. Rao, W. R. Rawnsley, L. Rebenitsch, C. A. Remon, W. Schreyer, A. Sikora, S. Sidhu,
J. Sonier, B. Thorsteinson, S. Vanbergen, W. T. H. vanOers, Y. X. Watanabe, and D. Yosifov, “A beamline for fundamental neutron
physics at TRIUMF,” Nucl. Instrum. Methods Phys. Res. A 927, 101–108 (2019).
S. Ahmed, E. Altiere, T. Andalib, B. Bell, C. P. Bidinosti, E. Cudmore, M. Das, C. A. Davis, B. Franke, M. Gericke, P. Giampa, P. Gnyp,
S. Hansen-Romu, K. Hatanaka, T. Hayamizu, B. Jamieson, D. Jones, S. Kawasaki, T. Kikawa, M. Kitaguchi, W. Klassen, A. Konaka,
E. Korkmaz, F. Kuchler, M. Lang, L. Lee, T. Lindner, K. W. Madison, Y. Makida, J. Mammei, R. Mammei, J. W. Martin, R. Matsumiya,
E. Miller, K. Mishima, T. Momose, T. Okamura, S. Page, R. Picker, E. Pierre, W. D. Ramsay, L. Rebenitsch, F. Rehm, W. Schreyer,
H. M. Shimizu, S. Sidhu, A. Sikora, J. Smith, I. Tanihata, B. Thorsteinson, S. Vanbergen, W. T. H. van Oers, and Y. X. Watanabe, “First
ultracold neutrons produced at TRIUMF,” Phys. Rev. C 99, 025503 (2019).
J. Surbrook, M. MacCormick, G. Bollen, M. Brodeur, M. Eibach, K. Gulyuz, A. Hamaker, C. Izzo, S. M. Lenzi, D. Puentes, M. Redshaw,
R. Ringle, R. Sandler, S. Schwarz, P. Schury, N. Smirnova, C. Sumithrarachchi, A. A. Valverde, A. C. C. Villari, and I. T. Yandow,“Precision mass measurements of 44 V and 44m V for nucleon-nucleon interaction studies,” Hyperfine Interact 240, 65 (2019).
N. Kimura, R. Kodama, K. Suzuki, S. Oishi, M. Wada, K. Okada, N. Ohmae, H. Katori, and N. Nakamura, “Direct wavelength measurement of the visible M1 transition in Ba7+ with a novel calibration method,” Plasma and Fusion Research 14, 1201021 (2019).

[Proceedings]
F. Galtarossa, L. Corradi, S. Szilner, E. Fioretto, G. Pollarolo, T. Mijatović, D. Montanari, D. Ackermann, D. Bourgin, S. Courtin, G. Fruet,
A. Goasduﬀ, J. Grebosz, F. Haas, D. Jelavić Malenica, S. C. Jeong, H. M. Jia, P. R. John, D. Mengoni, M. Milin, G. Montagnoli,
F. Scarlassara, N. Skukan N. Soić A. M. Stefanini E. Strano, V. Tokić, C. A. Ur, J. J. Valiente-Dobón, and Y. X. Watanabe, “Light andheavy fragments mass correlation in the 197 Au + 130 T e transfer reaction,” IL NUOVO CIMENTO 42 C, 2–3 (2019).

Presentations[International conferences/workshops]
M. Wada (invited), “Towards precise mass measurements of Nh and Mc isotopes,” 4th International Symposium on Superheavy Elements(SHE2019), Hakone, Japan, December 1–5, 2019.
M. Wada (invited), “SHE-Mass-II setup for direct mass measurement of hot-fusion superheavy nuclides,” 6th International Conference
on the Chemistry and Physics of the Transactinide Elements (TAN2019), Wilhelmshaven, Germany, August 25–31, 2019.
M. Wada (invited), “Antiprotonic atoms with short-lived nuclei,” ECT∗ Antiproton-nucleus interactions and related phenomena, Trento,
Italy, June 17–23, 2019.
M. Wada (invited), “Towards comprehensive mass measurements with MRTOF mass spectrographs at RIKEN RIBF,” 2019 The Korean
Physical Society Spring Meeting, Daejeon, Korea, April 24–26, 2019.
M. Wada (invited), “Symbiotic mass measurement with ZD-MRTOF,” High Resolution Gamma-Ray Spectroscopy at the RIBF, Darmstadt,
Germany, April 10–12, 2019.
H. Miyatake (invited), “KISS Project,” 14th Asia-Pacific Physics Conference, Borneo, Indonesia, November 17–22, 2019.
H. Miyatake (invited), “Recent progress of researches with KISS and MRTOF,” China-Japan Collaboration Workshop on “Nuclear massand life for unraveling mysteries of r-process,” ITP/CAS, Beijing, China, October 9–13, 2019.
H. Miyatake (invited), “Recent progress of researches with KISS and MRTOF,” The 15th International Symposium on Origin of Matterand Evolution of Galaxies (OMEG15), Kyoto, Japan, July 2–5, 2019.
Y. Watanabe (invited), “RI production at low energies “Production of N = 126 nuclei and beyond using multinucleon transfer reactions,”
JSPS/NRF/NSFC A3 Foresight Program—Nuclear Physics in the 21st Century,” Nuclear Structure & Nuclear Reaction Joint Kickoﬀ
Meeting, Kobe, Japan, December 6–7, 2019.
Y. Watanabe (invited), “Recent experimental results of KEK Isotope Separation System (KISS),” 1-day workshop at GSI on new approaches to MNT reaction studies, Darmstadt, Germany, October 23, 2019.
Y. Watanabe (invited), “Recent experimental results of KEK Isotope Separation System (KISS),” The 13th International Conference on
Stopping and Manipulation of Ions and related topics (SMI-2019), Montreal, Canada, July 16–19, 2019.
Y. Watanabe (invited), “Experimental studies of neutron-rich nuclei around N = 126 at KEK isotope separation system,” The IV International Conference on Nuclear Structure and Dynamics (NSD2019), Venice, Italy, May 13–17, 2019.
Y. Watanabe (invited), “Production of N = 126 nuclei and beyond using multinucleon transfer reactions,” Physics between lead anduranium: in preparation of new experimental campaigns at ISOLDE, Leuven, Belgium, April 16–18, 2019.
Y. Hirayama (invited), “Study of nuclear structure in the vicinity of nuclear structure in the vicinity of N = 126 at KISS,” Vth Topical
Workshop on Modern Aspects in Nuclear Structure, Bormio, Italy, February 4–9, 2020.
Y. Hirayama (poster), “Nuclear spectroscopy of r-process nuclei in the vicinity of N = 126 by using KISS,” 27th International Nuclear- 415 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Physics Conference (INPC 2019), Glasgow, UK, July 29–August 2, 2019.
Y. Hirayama (invited), “Nuclear spectroscopy of r-process nuclei in the vicinity of N = 126 at KISS,” Physics between lead and uranium:in preparation of new experimental campaigns at ISOLDE, Leuven, Belgium, April 16–18, 2019. Hirayama P. Schury (invited),“Nuclear physics by multi-reflection time-of-flight mass spectroscopy at WNSC,” 27th International Nuclear Physics Conference (INPC2019), Glasgow, UK, July 29–August 2, 2019.
P. Schury (invited), “Present status and future plans for slow and stopped beams in RIKEN,” The 13th International Conference on
Stopping and Manipulation of Ions and related topics (SMI-2019), Montreal, Canada, July 16–19, 2019.
M. Rosenbusch (oral), “Dynamic ejection-field correction for MRTOF mass spectrometry of SHE using arbitrary mass references fromreliable sources,” 4th International Symposium on Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.
T. Niwase (poster), “Development and first results from a novel “α-TOF” detector used with a multi-reflection time-of-flight mass spectrograph,” 6th International Conference on the Chemistry and Physics of the Transactinide Elements (TAN2019), Wilhelmshaven,
Germany, August 25–31, 2019.
T. Niwase (oral), “Correlation measurement of precision mass and decay properties of nuclei via MRTOF-MS with α-ToF detector,” 4thInternational Symposium on Superheavy Elements (SHE2019), Hakone, Japan, December 1–5, 2019.

[Domestic conferences/workshops]‫ٶ‬෢Ӊ໵ʢ‫ޱ‬಄ൃදʣ, ʮKISS Ͱͷ֩෼ޫ‫ڀݚ‬ʯ, ୹ण໋ RI Λ༻͍ͨ֩෼ޫͱ֩෺ੑ‫ ڀݚ‬VI, ‫౎ژ‬େֶෳ߹‫ྗࢠݪ‬Պֶ‫ॴڀݚ‬, େࡕ෎‫۽‬औ, 2020 ೥ 1 ݄ 16–17 ೔.
‫ٶ‬෢Ӊ໵ʢট଴ߨԋʣ, ʮୈ 7 प‫ݩظ‬ૉՊֶ: ௒ॏ‫ݩ‬ૉͷ෺ཧͱԽֶʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ೥
17–25 ೔.
‫ٶ‬෢Ӊ໵ʢট଴ߨԋʣ, ʮୈ 3 ϐʔΫͱऴᖼྖҬʹର͢Δ࣮‫ݧ‬తΞϓϩʔνʯ, ‫ͭͰ֩ࢠݪ‬Ή͙ r ϓϩηε, ‫౎ژ‬େֶ‫ૅج‬෺ཧֶ‫ݚ‬‫ॴڀ‬, ‫౎ژ‬, 2019 ೥ 5 ݄ 22–24 ೔.
౉ᬒ༟ʢট଴ߨԋʣ, ʮPresent status of KISSʯ, RIKEN, RIBF Users Meeting2019, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 9 ݄ 3–4 ೔.
౉ᬒ༟ʢট଴ߨԋʣ, ʮNuclear researches relevant to r-process with KISS and MRTOFʯ, Ӊ஦ʹ͓͚Δ෺࣭ਐԽ—‫֩ࢠݪ‬ɾ‫ࢠݪ‬ɾ෼
ࢠ—ୈ 1 ճγϯϙδ΢Ϝ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 8 ݄ 1–2 ೔.
ฏࢁլҰʢ‫ޱ‬಄ൃදʣ, ʮKISS ͰͷΨεδΣοτ಺Ϩʔβʔ‫ڞ‬໐ΠΦϯԽ֩෼ޫʯ, ೔ຊ෺ཧֶձ 2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬,2019 ೥ 9 ೥ 17–25 ೔.
P. Schuryʢ‫ޱ‬಄ൃදʣ, ʮCurrent status and ongoing strategy for MRTOF-MS at WNSCʯ, SSRI-PNS Collaboration Meeting 2019, ཧԽֶ‫ॴڀݚ‬, ࿨ޫ, 2019 ೥ 9 ݄ 4 ೔.
ఉ੉‫ོڿ‬ʢ‫ޱ‬಄ൃදʣ, ʮCorrelation measurement mass and decay properties of short-lived α-decay nuclei via MRTOF with α-TOF
detector (MRTOF+α-TOF Λ༻͍ͨ୹ण໋ α ่յ֩छͷ࣭ྔ-่յಛੑଌఆ)ʯ, ೔ຊ෺ཧֶձୈ 75 ճ೥࣍େձ, ໊‫ݹ‬԰େֶ, ໊‫ݹ‬԰, 2020 ೥ 3 ೥ 16–19 ೔.
ఉ੉‫ོڿ‬ʢ‫ޱ‬಄ൃදʣ, ʮCorrelation measurement of precision mass and decay properties of 207Ra with MRTOF+α-TOFʯ. ೔ຊ์ࣹԽֶձୈ 63 ճ౼࿦ձ (2020), ͍Θ͖࢈‫ۀ‬૑଄‫ؗ‬, ͍Θ͖, 2019 ೥ 9 ݄ 24–26 ೔.
ఉ੉‫ོڿ‬ʢ‫ޱ‬಄ൃදʣ, ʮCorrelation measurement of precision mass and decay properties of 207Ra with MRTOF-MSʯ, ೔ຊ෺ཧֶձ
2019 ೥ळ‫ق‬େձ, ࢁ‫ܗ‬େֶ, ࢁ‫ܗ‬, 2019 ೥ 9 ೥ 17–25 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Events (April 2019 — March 2020)
RNC
Apr. 20

Wako Open Campus

May. 24

The 25th RBRC Management Steering Committee (MSC)

Jun.24–26

The 5th Nishina Center Advisory Council (NCAC)

Jun. 28

The 18th Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)

Jul. 10The 8th Industrial Program Advisory Committee (In-PAC)

Jul.31–Aug.9

Nishina School

Dec.16–18

The 20th Program Advisory Committee for Nuclear Physics Experiments at RI Beam Factory (NP-PAC)

Jan.24

The 19th Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)

CNS
Aug. 21–27

18th CNS International Summer School CNSSS19
https://indico2.cns.s.u-tokyo.ac.jp/event/65/- 417 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 53

Press Releases (April 2019−March 2020)
RNC
May. 278

R. Taniuchi, P. Doornenbal, H. Sakurai,Radioactive Isotope Physics Laboratory

Jun. 15

Transverse momentum dependent production cross sections of charged pions, kaonsand protons produced in inclusive e +e− annihilation at √s = 10.58 GeV

R. Seidl, Radiation Laboratory

Jun. 26

Gamma-ray Glow preceding Downward Terrestrial Gamma-ray FlashY. Wada, High Energy Astrophysics Laboratory

Jul. 5Enhancement of element production by incomplete fusion reaction with weakly bound W. He, H. Otsu, Fast RI Data Team, H. Sakurai,
nucleus deuteron
Nuclear Transmutation Data Research Group

Aug. 9Proposal of a 1-ampere-class deuteron single-cell linac for nuclear transmutation

H. Okuno, High-Power Target R&D Team, H.
Sakurai, Nuclear Transmutation Data ResearchGroup

Sep. 12

X-ray pumping of the 229Th nuclear clock isomer

H. Haba, RI Application Research Group

Oct. 18

Quasifree neutron knockout from 54Ca corroborates arising N = 34 neutron magic
number

P. Doornenbal, H. Sakurai, Radioactive Isotope
Physics Laboratory

Nov. 19

Location of the neutron dripline at fluorine and neon

D.S. Ahn, N. Fukuda, N. Inabe, BigRIPS Team,
T. Kubo, Research Instruments Group

Nov. 26

A method of collecting trace amounts of vermilion from artifacts for source estimation
K. Takahashi, Y. Motizuki, Astro-Glaciology
by sulfur isotope (δ34S) analysis: use of sulfur-free adhesive tape to minimize damage
Research Groupto the artifact body during samplingNov. 26

Underlying structure of collective bands and self-organization in quantum systems

T. Otsuka, Nuclear Spectroscopy Laboratory

Nov. 29

Energy of the 229Th nuclear clock isomer determined by absolute γ-ray energy
difference

H. Haba, RI Application Research Group

Mar. 5

Possible lightest Ξ hypernucleus with modern ΞN interactions

E. Hiyama, Strangeness Nuclear Physics
Laboratory, T. Doi, Quantum Hadron Physics
Laboratory

Mar. 13

Swelling of doubly magic 48Ca core in Ca isotopes beyond N = 28

M. Tanaka, Nuclear Spectroscopy Laboratory,
M. Takechi, M. Fukuda, H. Sakurai, Radioactive
Isotope Physics Laboratory

Mar. 17

g-Factor of the 99Zr (7/2+) isomer: monopole evolution in shape coexisting region

Y. Ichikawa, J.-M. Daugas, H. Ueno, Nuclear
Spectroscopy Laboratory

Ni revealed as a doubly magic stronghold against nuclear deformation- 418 -

VII. LIST OF PREPRINTS

Ⅶ. LIST OF PREPRINTS

RIKEN Accel. Prog. Rep. 53

List of Preprints (April 2019―March 2020)
RIKEN NC-NP
Not Applicable

RIKEN NC- AC
Not Applicable

RIKEN MP
Not Applicable

RIKEN QHP
411

Self-consistent random phase approximation based on the relativistic Hartree-Fock theory: Role
Z. Wang et al.
of ρ-meson tensor coupling

412

Field-theoretical Derivation of the Negative Magnetoresistance with the Chiral Anomaly

K. Fukushima, Y. Hidaka

413

QCD-like phase diagram with Efimov trimers and Cooper pairs in resonantly interacting SU(3)Fermi gases

H. Tajima, P. Naidon

414

Non-relativistic expansion of Dirac equation with spherical scalar and vector potentials bysimilarity renormalization group

H. Liang, Y. Guo415

I = 2 ππ potential in the HAL QCD method with all-to-all propagators

Y. Akahoshi et al.

416

String confinement in 2-form lattice gauge theory

T. Hayata, A. Yamamoto

417

Spontaneous symmetry breaking and Nambu-Goldstone modes in open quantum and classicalsystems

Y. Minami, Y. Hidaka

CNS-REP98

CNS Annual Report 2018

H. Nagahama

KEK-REP
1904.097

An inexpensive biasing system for use in electrostatic steering of ionsP. Schury, M. Wada

26
1904
.115
89
1910
.104
94

Development of an “α-TOF” detector for correlated measurement of atomic masses and decay
T. Niwase et al.
properties
Accurately accounting for effects on times-of-flight caused by finite field-transition times during
M. Rosenbusch et al.
the ejection of ions from a storage trap: A study for TOF and MRTOF mass spectrometry

Nishina Center Preprint server (not including Partner Institution) can be found at
http://nishina-preprints.riken.jp/- 419 -

VIII. LIST OF SYMPOSIA,
WORKSHOPS & SEMINARS

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 53

List of Symposia & Workshops (April 2019―March 2020)
RNC
1

Nishina School 2019

RIBF Conf. Hall, RIKEN
Wako Campus

Jul. 30–Aug. 92

8th SUNFLOWER workshop

Osaka University
Nakanoshima Center

Aug. 26–28

3

New Trends in Integrable Systems 2019

Media Center, Osaka City
University (Sugimoto
campus)Sep. 9–20

458th Nuclear Chemistry Summer School

Yufutopia, Oita Prefecture

Sep. 11–14

5

4th International Symposium on Superheavy Elements (SHE2019)

The Prince Hakone Lake
AshinokoDec. 1–5

6

International Symposium on Clustering as a Window on the Hierarchical Structure of Quantum Ryotiku Bettei, Oita
Prefecture
Systems (CLUSHIQ2020)

Jan. 23–24

7

RIKEN Symposium “Practical application of Ion Beam Breeding in the past 20 years”

Suzuki Umetaro Hall

Jan. 23–24

8

Japan-France Joint Workshop on "Clusters in Quantum Systems: from Atoms to Nuclei andKyushu University
Hadrons"

9

18th AVF Liaison Meeting

Nishina Hall

10

3rd RIBF Young Researchers’ Discussion: Future of Physics of Exotic Nuclei

Integrated Innovation
Building (IIB), RIKEN Kobe Feb. 19–21
Campus11

Scientific Research on Innovative Areas “Clustering as a Window on the Hierarchical of Quantum
Nishina Hall
Systems School”

Jan. 27–31

Feb. 18–19

Mar. 2–4

List of Seminars (April 2019―March 2020)
Nuclear Physics Monthly Colloquium
Not held in 2019

RIBF Nuclear Physics Seminar
1

Takaharu Otsuka(RNC)

Tin isotopes: Are they dull round nuclei?
https://indico2.riken.jp/event/3022/

Apr. 92

Inoue Yoshiyuki(RIKEN)

Nature of coronae around supermassive black holes
https://indico2.riken.jp/event/3040/

May 14

3

William B. Brinckerhoff(NASA)

Mass spectrometers to Mars and beyond
https://indico2.riken.jp/event/3049/

May 16

4

Newcomers to Nishina
Center in 2019

Newcomers’ seminarhttps://indico2.riken.jp/event/3052/

May 21- 421 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 53

5

Ryo Taniuchi(U. York)

78

Ni revealed as a doubly magic stronghold against nuclear deformation
https://indico2.riken.jp/event/3069/

May 28

6

Koichi Sato
(Osaka City U.)

Large-amplitude quadrupole shape mixing probed by the (p, p′)reactionhttps://indico2.riken.jp/event/3081/

Jun. 11

7

Xing Fan(Harvard U.)

Towards an improved electron and positron magnetic moment measurement as a test of theStandard Model and CPT symmetry
https://indico2.riken.jp/event/3100/

Jul. 8

8

Enrico Rinaldi(RIKEN, BNL)The neutron lifetime with near-Exascale computing
https://indico2.riken.jp/event/3092/

Jul. 99Toshio Suzuki(Tohoku U.)

Is electron scattering useless to study neutron distribution in nuclei?
https://indico2.riken.jp/event/3134/

Oct. 1110

Masayuki Yamagami(U. Aizu)

Tetrahedral deformation in nuclei
https://indico2.riken.jp/event/3147/

Oct. 15

11

Sohtaro Kanda(RNC)

Precision microwave spectroscopy of the ground-state hyperfine splitting in muonium atom
https://indico2.riken.jp/event/3180/

Nov. 26

12Kohl(Hampton U.)

The proton radius puzzle and its intersections
https://indico2.riken.jp/event/3190/

Dec. 913

Andrea Vitturi(INFN)The molecular cluster model for 12C and the description of inelastic processes in 12C induced byalpha particles
Dec. 12https://indico2.riken.jp/event/3181/

14

DeukSoon Ahn(RNC)

Location of the neutron dripline at fluorine and neon
https://indico2.riken.jp/event/3309/

Jan. 14

15

Or Hen(MIT)

Short-range correlations and the quarks withinhttps://indico2.riken.jp/event/3317/

Jan. 21

16

Muhsin N. Harakeh(KVI-CART, GANIL, GSI)

Co-organized by CNS and RNC
Nuclear compression modes from stable to exotic nuclei
https://indico2.riken.jp/event/3324/

Feb. 3

Seminar by Each Laboratory
Nuclear Science and Transmutation Research Division
1

José R. C. López-Urrutia(Max-Planck)

Hard-core atomic physics: highly charged ions
https://indico2.riken.jp/event/3030/

Apr. 112

Roland Diehl(Max-Planck)Gamma-ray spectroscopy from nuclei in the cosmos
https://indico2.riken.jp/event/3103/

Jul. 93

Shigeki Fujiyama(RIKEN)

計算機を活用した固体 NMR の解析法
https://indico2.riken.jp/event/3105/

Jul. 24

4

Yugo Nagata(Tokyo U. Sci.)

静周期磁場によるポジトロニウム超微細構造の観測実験
https://indico2.riken.jp/event/3162/

Nov. 5

5

Takatoshi Aoki
(U. Tokyo)

極低温 Fr 原子を用いたパリティ非保存効果誘起の光シフトの研究： 標準模型を超えた新物理と核のアナポールモーメン
トDec. 20https://indico2.riken.jp/event/3198/

6

Yoichi Yatsu(Tokyo Tech)

超小型衛星による宇宙開発の実態 –成功と挫折の軌跡–

Jan. 28

7

Daiki Yamashita(RIKEN)

Er-implanted silica lasers based on Si nanobeam cavities
https://indico2.riken.jp/event/3356/

Feb. 27

High Energy Astrophysics Lab. Seminar -> http://astro.riken.jp/wordpress/?page_id=65- 422 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 53

Subnuclear System Research Division
1

Hiromichi Nishimura(RBRC)QHP Seminar:
Effective potential for the Polyakov loop to higher loop order

Apr. 1

2

Alex Kovner(U Connecticut)

NT / RIKEN seminar
The Color Glass Condensate density matrix: Lindblad evolution, entanglement entropy andWigner functional

Apr. 5

3

Tamura Hirokazu(Tohoku U.)

Nuclear physics with strange quarks --Resent results and future prospects at J-PARC—
https://indico2.riken.jp/event/3026/

Apr. 84

Paolo Bedaque(U. Maryland)

NT / RIKEN seminar:
A Complex path around the sign problem

Apr. 125

Anatoly Radyushkin,(ODU/Jlab)

NT / RIKEN seminar:
Parton distributions in Euclidean space

Apr. 19

6

Keh-Fei Liu(U. Kentucky)

RIKEN Lunch Seminar:
Partons from the path-integral formalism of the hadronic tensor

Apr. 25

7

Gokce Basar(UiC)

RIKEN Lunch Seminar:
Relativistic hydrodynamic fluctuations

May 3

8

Shoichiro Tsutsui(RIKEN)QHP Seminar:
Applicability of the complex Langevin method for QCD at finite density

May 8

9

Hiroyuki Fujioka(Tokyo Tech)

第 4 回「物質階層を横断する会」～ハドロン・原子核・原子・分子合同ミーティング Ξハイペロン吸収によるダブルΛハイパー
核フラグメント生成
https://indico2.riken.jp/event/3047/

May 1010Michael Strickland(Kent State U.)

NT / RIKEN seminar:
The non-equilibrium attractor: Beyond hydrodynamics

May 1011

Masashi Kaneta(Tohoku U.)

γ d → Λ K+ n 反応での終状態相互作用を通したΛn 間力測定実験計画
https://indico2.riken.jp/event/3070/

May 2012

Enrico Rinaldi(RIKEN)QHP Seminar:
Composite Dark MatterMay 22

13

Semeon Valgushev(BNL)

RIKEN Lunch Seminar:
Complex saddle points of path integrals

May 2314

Shoichi Sasaki(Tohoku U.)

SNP Seminar:
Nucleon form factors from lattice QCD at the physical pointhttps://indico2.riken.jp/event/3042/

May 24

15

Henry Lamm
(UMD)

NT / RIKEN seminar
Pieces of the puzzle: Reaching QCD on quantum computers

May 24

16

Akio Tomiya(RBRC)RIKEN Lunch Seminar:
Applications of machine learning to computational physics

May 3017

Kazuya Mameda(RIKEN)QHP Seminar:
Chiral kinetic theory with general relativity

Jun. 518

Hsiang-nan Li(NCTS)NT / RIKEN seminar:
D meson mixing via dispersion relation

Jun. 14

19

Nora Brambilla(TUM)

QHP Seminar:
Nonrelativistic effective field theories for heavy quarkonium

Jun. 20

20

Minoru Tanaka(Osaka U.)

QHP Seminar:
Search for new physics in isotope shifts of atomic spectra
https://indico2.riken.jp/event/3091/

Jul. 1021

Javad Shabani(NYU)

NT / RIKEN seminar:
Topological superconducting qubits

Jul. 1222

Paul Caucal(Saclay)

RIKEN Lunch Seminar:
Deciphering the zg distribution in ultrarelativistic heavy ion collisions

Jul. 25- 423 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 53

23

Takafumi Niida(Tsukuba U.)

QHP Seminar:
Global and local polarization in heavy-ion collisions

Jul. 3124

Fabio Siringo(U. Catania)

NT / RIKEN seminar
Perturbation Theory of Non-Perturbative QCD

Aug. 225

Jnanadeva Maharana(Inst. Physics,
Bhubaneswar)

NT / RIKEN seminar:
Topological Superconducting Qubits

Aug. 726

Kiminad Mamo
(Stony Brook U.)

NT / RIKEN seminar
DIS on a quantum extremal RN-AdS black hole: with application to DIS on a nucleus

Aug. 827

Ryo Karakida(AIST)RIKEN Lunch Seminar:
Mean field approach to the Fisher information matrix in deep neural networks

Aug. 15

28

Jean-Francois Paquet(Duke U.)NT / RIKEN seminar:
Aug. 16
Effective and temperature-dependent viscosities in a hydrodynamically-expanding QCD plasma

29

Daniel Harlow(MIT)

NT / RIKEN seminar:
Symmetries in quantum field theory and quantum gravity

Aug. 2330

Masazumi Honda(Cambridge)

RIKEN Lunch Seminar:
Quantum black hole entropy from 4d supersymmetric Cardy formula

Aug. 29

31

Shailesh Chandrasekharan(Duke U.)NT / RIKEN seminar:
Qubit regularization of quantum field theories

Sep. 632

Andrey Tarasov(BNL)

RIKEN Lunch Seminar
Deeply inelastic scattering structure functions on a hybrid quantum computer

Sep. 1233

Derek Teaney(Stony Brook)

NT / RIKEN seminar:
The bulk viscosity of QCD in the chiral limit

Sep. 19

34

Nodoka Yamanaka(Kyoto U.)

QHP Seminar:
Nuclear electric dipole moment and the axions
https://indico2.riken.jp/event/3115/

Sep. 25

35

Andrecia Ramnath(U. Jyvaskyla)

RIKEN Lunch Seminar:
Rapidity correlators at unequal rapidity

Sep. 26

36

Giuliano Giacalone(IPhT – Saclay)

NT / RIKEN seminar:
Observing the deformation of nuclei with relativistic nuclear collisions

Sep. 27

37

Adrien Florio(EPFL)RIKEN Lunch Seminar
Chiral charge dynamics in Abelian gauge theories at finite temperature

Oct. 338

Gerald Dunne(U. Connecticut)

NT / RIKEN seminar:
Resurgence and non-perturbative physics

Oct. 4

39

Ming Li(U. Connecticut)

NT / RIKEN seminar
JIMWLK equation from quantum-classical correspondence

Oct. 1140

Rasmus Larsen(BNL)

RIKEN Lunch Seminar:
Bottomonia in QGP from lattice QCD: Beyond the ground states

Oct. 17

41

Derek Teaney(Stony Brook U.)

NT/RIKEN Seminar:
The bulk viscosity of QCD in the chiral limit

Oct. 18

42

Koichi Hattori(YITP)QHP Seminar:
Recent progress in relativistic magnetohydrodynamics

Oct. 23

43

Miguel A. Vazquez-Mozo(U. Salamanca)

QHP Seminar:
Anomalous (super)fluids and differential geometry

Oct. 2344

Sophia Han(Ohio U.)

NT/RIKEN Seminar:
Detectability of phase transitions from multi-messenger observations

Oct. 25

45

Joseph Kapusta

Special NT/RIKEN Seminar:
Relaxation time for strange quark spin in rotating quark-gluon plasma

Oct. 31- 424 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 53

46

Alba S. Ontoso(BNL)

RIKEN Lunch Seminar:
Revisiting the discovery potential of the isobar run at RHIC

Nov. 1447

Paul Chesler(Harvard U.)

NT/RIKEN Seminar:
Critical gravitational collapse and thermalization in small systems

Nov. 2248

Savely Karshenboim(LMU)

QHP Seminar:
New quantum SI units and fundamental constants

Nov. 26

49

Nicolas Wink
(Heidelberg)

Special NT/RIKEN Seminar:
Elementary correlation functions in QCD and their application

Dec. 450

Amit Kumar

NT/RIKEN Seminar
Probing quark-gluon plasma at high resolution

Dec. 6

51

Florian Cougoulic

NT/RIKEN Seminar:
Helicity-dependent generalization of the JIMWLK evolution and MV modelDec. 13

52

Scott Lawrence

NT/RIKEN Seminar:
From qubits to quarks: Parton physics on a quantum computer

Dec. 2053

Kaushik Roy(Stony Brook U.)

RIKEN Lunch Seminar:
NLO impact factor for inclusive photon+dijet production in e + A DIS at small x

Jan. 23

54

Stefan Hoeche(Fermilab)

NT/RIKEN Seminar:
Towards precision event simulation for collider experiments

Jan. 24

55

Dean Lee

NT/RIKEN Seminar
New tools for the quantum many-body problem

Feb. 7

56

Xiangdong Ji

Special NT/RIKEN Seminar:
Partonic structure of the proton from large momentum effective theory

Feb. 1057

Greg Jackson(U. Bern)

RIKEN Lunch Seminar:
Shedding light on photon and dilepton spectral functions

Feb. 1358

Carlota A. Casas

NT/RIKEN Seminar:
Solving the medium-induced gluon radiation spectrum for an arbitrary number of scatterings

Feb. 1459

Eduardo Fraga

Special NT/RIKEN Seminar:
Critical dynamics from small, noisy, fluctuating systems

Feb. 1860

Leticia Palhares

Special NT/RIKEN Seminar:
Infrared gluon mass and the Gribov-Zwanziger model of nonperturbative Yang-Mills theories

Feb. 19

61

Kazuki Ikeda(Osaka U.)

RIKEN Lunch Seminar:Phase transitions of quantum annealing and quantum chaos

Feb. 2062

Duff Neill

NT/RIKEN Seminar:
Soft fragmentation on the celestial sphereFeb. 21

63

Tomoya Hayata (Keio U.)

QHP Seminar:
Chital magnetic/vortical effect of lightFeb. 26

64

Katerina Chatziioannou

NT/RIKEN Seminar:
Studying supranuclear matter with gravitational waves from neutron star binaries

Feb. 28

65

Yong Zhao(BNL)

RIKEN Lunch Seminar:
Nonperturbative Collins-Soper kernel from lattice QCD

Mar. 566

Abha Rajan(BNL)

RIKEN Lunch Seminar:
Ioffe time behavior of PDFs and GPDs

Mar. 12QHP Seminar -> http://ribf.riken.jp/QHP/seminar.html
SNP Seminar -> http://snp.riken.jp/seminar.html
RIKEN/BNL Lunch Time Talk -> https://sites.google.com/site/rikenlunch/talks- 425 -

理化学研究所

埼玉県 和光市 広沢
RIKEN 2020-050