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

52

RIKEN Accelerator Progress Report
vol.

52

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 2018 vol.52
This is an unabridged version of the 52nd 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
In ﬁscal year 2018, RIKEN entered its 4th midterm, which
will last for seven years. For this new midterm period,
we have modiﬁed the Center’s organization. The former
RIBF Research Division was split into three divisions,
the Nuclear Science and Transmutation Research Division, Research Facility Development Division, and Accelerator Application Research Division. The change makes
our infrastructure components, application research, andnuclear transmutation research more visible. We merged
the Theoretical Research Division into the Subnuclear Research Division, reﬂecting the recent promotions of theleading theorists in the Nishina Center.
We made this change, in part, because from thismidterm, the RIKEN Nishina Center is categorized as a
strategic research center, switched from the former infrastructure center. This means that we need to place moreemphasis on our research strategy than on our user support as an accelerator facility. With this organizational change,
we can pursue the enhancement of both RIKEN’s own strategic research and user support for the community.
The Heisei era ended in April 2019. Considering the festive mood for the era change, I feel that it was much morenatural for the Japanese imperial transition to have taken place through abdication rather than by passing of theEmperor. However, as stated by the Heisei Emperor, we have experienced so many disasters over the 30 Heisei years,
and the one of the largest was the accident at the Fukushima Nuclear Power Plant. We still remember that many ofus went there to perform radiation measurements of the local people and soil in Fukushima.
Nuclear energy is one of the most important social knowledges born from nuclear science. Unfortunately, with theradioactive waste generated by nuclear reactors becoming a social problem, because of the Fukushima disaster, andthe decommissioning of the “Monju” plan, the nuclear energy cycle of our nation has failed. As nuclear physicists,
we must now reconsider energy issues and identify the correct path for the use of nuclear energy by scientiﬁcallyreconstructing its usefulness. Continuing operation of large nuclear power plants is not necessarily the only way toachieve this goal.
The Nishina Center has spearheaded a research eﬀort to transform radioactive waste into short-lived nuclides withthe use of the accelerator through the ImPACT Project. The patent “Radioactive Waste Processing Method,” which
originated from the Project, was awarded the 21st Century Invention Award for FY2018 by the Japan Institute ofInvention and Innovation. The award ceremony was attended by Imperial Prince Takamatsunomiya Nobuhito. Thisis a very small step toward the real goal of the nuclear energy problem, but we have to pursue solutions patiently
and continuously.
The year 2019 was proclaimed the International Year of the Periodic Table of Chemical Elements by UNESCO.
The opening ceremony was held in Paris in January, and the Year will conclude at the closing ceremony scheduled forTokyo on December 5. The 150th anniversary of the creation of the periodic table by Mendeleev as well as the recent
completion of the 7th row of the table will be celebrated. Tokyo was chosen as the venue of the closing ceremony
because of the discovery of nihonium.
The scientiﬁc goal of the Nishina Center is to obtain more research results from experiments conducted at the
RIBF, promote facility expansion and reinforcement of the RIBF, and discover elements 119 and 120. We havealready begun experiments to search for element 119. Trial operation of the superconducting RILAC will begin soon,
providing a substantial boost to the search experiment. Only God knows whether the elements will be discovered in
the near future or in 10 years.

Hideto En’yo
Director
RIKEN Nishina Center for Accelerator-Based Science

CONTENTS

RIKEN Accel. Prog. Rep. 52 (2019)

C O N T E N T S
PagePREFACE
Ⅰ. HIGHLIGHTS OF THE YEARFirst observation of 20B and 21B ···········································································································
S. Leblond et al.

1

Gamow–Teller giant resonance in 132Sn ··································································································
M. Sasano, J. Yasuda et al.

2First spectroscopy of the near drip-line nucleus 40Mg ·················································································
H. L. Crawford, P. Fallon et al.

3

Interplay between nuclear shell evolution and shape deformation revealed by magnetic moment of 75Cu·····················
Y. Ichikawa et al.

4Mass measurements of neutron-rich Ni isotopes in Rare RI Ring ···································································A. Ozawa et al.

5

Discovery of 60Ca and Implications For the Stability of 70Ca ·········································································
O. B. Tarasov

6

Nuclear surface diffuseness revealed in nucleon-nucleus diffraction ································································
W. Horiuchi and A. Kohama

7

Proton- and deuteron-induced reactions on 107Pd and 93Zr at 20–30 MeV/nucleon ················································
M. Dozono et al.

8Transverse momentum dependent fragmentation measurements in Belle···························································
R. Seidl

9

Measurement of elliptic flow of single electrons from semi-leptonic decay of charm and bottom hadrons—in Au+Au collisions at √ sNN = 200 GeV····························································································
Y. Ueda et al.

10

The chiral propulsion effect················································································································
Y. Hirono et al.

11

Superconducting RILAC booster ·········································································································
N. Sakamoto et al.

12

Remodeling of acceleration cavity resonators for RIKEN Ring Cyclotron ·························································
K. Yamada et al.

13

He gas stripper with N2 gas-jet curtain ···································································································
H. Imao et al.

14

Upgrade of particle selection system for Rare RI Ring experiments·································································
Y. Abe et al.

15

Aberration correction study for high-resolution optics of BigRIPS using sextupole magnets ···································
T. Nishi et al.

16

In-gas-jet laser ionization spectroscopy at KISS························································································
Y. Hirayama et al.

17

Microgram-order palladium isotope separation by odd-mass-selective photoionization··········································
T. Sonoda and T. Kobayashi

18

Introducing silver atoms into superfluid helium for precision laser spectroscopy ·················································
W. Kobayashi et al.

19

Magnetic properties of Alkali-metal Superoxide, NaO2················································································
F. Astuti et al.

20

Mass spectrometric speciation of mononuclear Re carbonyls in the gas phase·····················································
Y. Wang et al.

21

Practical synthesis of 211At-labeled immunoconjugate by double click method for α -emission cancer radiotherapeutics ···K. Fujiki and K. Tanaka et al.

22

Activation cross sections of α -induced reactions on natZn for Ge and Ga production··············································
M. Aikawa et al.

23

RIKEN Accel. Prog. Rep. 52 (2019)

CONTENTS

A novel mutation induced by Ar-ion-irradiation affect grain length and improve yield in rice···································
R. Morita et al.

24

Recent progress in overcoming interspecific hybrid sterility in rice ·································································
Y. Koide et al.

25

Improved and robust method to efficiently deplete repetitive elements from complex plant genomes ·························
H. Ichida and T. Abe

26

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

1. Nuclear Physics
Breakup of 9C studied at SAMURAI ·····································································································
A. I. Chilug, V. Panin et al.

27

Cluster structure of neutron-rich beryllium isotopes investigated by cluster quasi-free scattering reaction ····················
P. Li, D. Beaumel

28

Particle identification in 11Li(p, n) experiment at SAMURAI ········································································Y Hirai et al.

29

Neutron-gamma separation performance of PANDORA in SAMURAI30 experiment ···········································
Y. Hirai et al.

30

Gamow-Teller resonance in 14Be(p, n) reaction·························································································
J. Gao and L. Stuhl

31

Systematic study of one-proton and two-proton knockout reactions by deuterium target·········································
M. Miwa et al.

32

Study of spin-isospin response of 11Li (SAMURAI30 experiment)··································································
L. Stuhl et al.

33

Overview of the experimental setup of SAMURAI30 to measure the 11Li(p, n) reaction in inverse kinematics···············
M. Sasano, L. Stuhl et al.

34

Neutron-neutron correlation in Borromean nucleus 11Li via the (p, pn) reaction···················································
Y. Kubota et al.

35

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

36

Recent results of collective flow for SπRIT-TPC experiment·········································································
M. Kurata-Nishimura et al.

37

New implant-decay correlation method for β -delayed neutron emission measurements with the BRIKEN setup·············
O. Hall et al.

38

Progress on the measurements of Pn-values and half-lives for understanding the formationof the r-process rare-earth peak·····································································································
A. Tarifeño-Saldivia

39

97
β decays of the heaviest N = Z − 1 nuclei and proton instability of In······························································
J. Park et al.

40

Beta-gamma spectroscopy of neutron-rich 150Ba························································································
R. Yokoyama et al.

41

Preliminary results on β -decay of the Tz = −1 nucleus 66Se at RIBF ·································································
P. Aguilera et al.

42

Study of β -decay of 71Kr····················································································································A. Sveiczer et al.

43

Coexisting single-particle and octupole states in 133Sn·················································································
G. Simpson et al.

44

Inelastic scattering of neutron-rich Ni and Zn isotopes off a proton target··························································
M. L. Cortés et al.

45

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

46

Track distortion due to ion back flow in CAT-S at RIBF113: 132Sn(d, d’) measurement ··········································
S. Ota et al.

47

First mass measurements of neutron-rich calcium isotopes, 55–57Ca ··································································
S. Michimasa et al.

48

CONTENTS

RIKEN Accel. Prog. Rep. 52 (2019)

Re-measurement of the 4He(8He, 8Be) reaction··························································································
S. Masuoka, S. Shimoura et al.

49

Evaluation of 79Se(n, γ )80Se reaction by measuring 77, 79Se(d, p)78, 80Se reactions····················································
N. Imai, M. Dozono et al.

50

Fine tuning of isochronism in Rare RI Ring using resonant Schottky monitor ·····················································
F. Suzaki et al.

51

Preliminary analysis of the mass measurement experiment in the south-western region of 132Sn with Rare RI Ring·········
H. F. Li et al.

52

First online experiment of α -ToF detector with MRTOF-MS ········································································
T. Niwase et al.

53

195

β -γ spectroscopy of Os at KISS ········································································································
M. Ahmed et al.

54

Feasibility study of 199Pt Q-moment measurement using in-gas-jet laser ionization spectroscopy at KISS·····················
H. Choi et al.

55

Electric field gradient of ZnO crystal measured by β -NQR of 23Ne ·································································
H. Nishibata et al.

56

7

Be target production to measure 7Be(d, p) reaction for the primordial 7Li problem in Big-Bang Nucleosynthesis···········
A. Inoue et al.

57

New measurement of 8Li(α , n)11B reactions·····························································································
Y. Mizoi et al.

58

Trojan Horse Method-based study of the 18F(p, α )15O reaction at astrophysical energies: update on the 2015 run············
S. Cherubini et al.

59

Gamow-Teller transitions in 6He with PANDORA······················································································
L. Stuhl et al.

6021
β -NMR measurements for O at HIMAC·······························································································
A. Gladkov et al.

61

RI beam production at BigRIPS in 2018 ································································································
Y. Shimizu et al.

62

Measurement of production cross-section and momentum distribution of isotopes produced from 18O beam·················
H. Takeda et al.

64

Cross-section measurement of neutron-rich isotopes produced from an RI beam of 132Sn using a two-step scheme ·········
H. Suzuki et al.

65

2. Nuclear Physics (Theory)
Improvement of functionals in density functional theory using inverse Kohn-Sham methodand density functional perturbation theory ························································································
D. Ohashi, T. Naito et al.

67

Coulomb exchange functional with generalized gradient approximation for self-consistent
Skyrme Hartree-Fock calculations ·································································································
T. Naito, X. Roca-Maza et al.

68

Joint project for large-scale nuclear structure calculations in 2018 ··································································
N. Shimizu et al.

69

Bubble nuclei within the self-consistent Hartree-Fock mean field plus pairing approach ········································
L. Tan Phuc et al.

70

Dineutron correlation and large quadrupole collectivity in deformed Mg isotopes near neutron drip line ·····················
M. Yamagami

71

Isoscalar and isovector spin responses in sd-shell nuclei ··············································································
H. Sagawa and T. Suzuki

72

Self-consistent constrained HFB in odd-A nuclei ······················································································
K. Sugawara-Tanabe and K. Tanabe

73

Nuclear symmetry energy and the breaking of the isospin symmetry: how do they reconcile with each other ?··············
X. Roca-Maza et al.

74

Neutron-proton pairing correlations and deformation for N = Z nuclei in pf-shell using deformed BCS
and HFB approach····················································································································
E. Ha et al.

75

RIKEN Accel. Prog. Rep. 52 (2019)

CONTENTS

Spin-singlet and spin-triplet pairing correlations on shape evolution in sd-shell N = Z Nuclei ··································
E. Ha et al.
Low-lying collective excited states in non-integrable pairing models based on stationary phase approximation
to the path integral ···················································································································
F. Ni et al.
Study of giant dipole resonance in hot rotating light mass nucleus 31P ······························································
D. Mondal et al.

76

77
78

3. Nuclear Data
Verification test of 107Pd transmutation ···································································································
Y. Miyake et al.

79

Measurement of neutron production from 7 MeV/nucleon α incidence on a Bi target ···········································
K. Sugihara et al.

80

EXFOR compilation of RIBF data in 2018 ·····························································································
S. Jagjit et al.

81

4. Hadron Physics
Preliminary result of the transverse single spin asymmetry in very forward π0 production in 510 GeV p↑ + p collisions ····M. H. Kim

83

The stability of energy scale for RHICf photon measurement during the 2017 operation ········································
K. Sato et al.

84

Cross section and longitudinal single-spin asymmetry AL for forward W± → μ ±ν production in polarized p + p collisions–at √ s = 510 GeV ······················································································································
R. Seidl

85

Progress in analysis technique for extracting light-antiquark flavor asymmetry by SeaQuest at Fermilab ·····················
K. Nagai et al.

86

Forward hadron calorimeter R&D ········································································································
Y. Goto et al.

87

Development of the intermediate silicon tracker for sPHENIX experiment at RHIC ·············································
I. Nakagawa

88

Tracking performance simulation for INTT at sPHENIX ·············································································
T. Todoroki et al.

89

Preparation status of the J-PARC E16 experiment in 2018············································································
S. Yokkaichi

90

Spectroscopy of pionic atoms in 122Sn(d, 3He) reaction and angular dependence of the formation cross sections·············
T. Nishi et al.

91

Isotope identification in nuclear emulsion plate for double-hypernulcear study····················································
S. Kinbara et al.

92

5. Hadron Physics (Theory)
Short range π J/ψ − D D̄* interaction ······································································································
Y. Yamaguchi et al.

93

Proton decay matrix elements at physical quark mass ·················································································
Y. Aoki et al.

94

The πγ → ππ transition and the ρ radiative decay width from lattice QCD ························································
S. Meinel et al.

95

Neutron stars from an effective quark theory of QCD ·················································································
T. Tanimoto96

6. Particle Physics
Baryon spectrum of an SU(4) composite Higgs theory ················································································
E. T. Neil et al.

97

Updated empirical formulae of the masses of elementary particles··································································
Y. Akiba

98

A model of the empirical mass formulae of elementary particles ····································································
Y. Akiba

99

CONTENTS

RIKEN Accel. Prog. Rep. 52 (2019)

7. Astrophysics and Astro-Glaciology
High-sensitivity sulfur isotopic measurements for Antarctic ice core analyses·····················································
K. Takahashi et al.

101

Mass Measurements with the Rare-RI Ring for the A = 130 r-process Abundance Peak ·········································S. Naimi

102

8. Accelerator
Construction of New 28-GHz ECR ion source for RILAC············································································
T. Nagatomo et al.

103

Development of prototype superconducting linac for low-beta ions·································································
N. Sakamoto et al.

104

Performance test of bulk-niobium cavities for new superconducting linear accelerators ·········································
K. Yamada et al.

105

Input power coupler for SRILAC ·········································································································
K. Ozeki et al.

106

Development of RIKEN 28 GHz SC-ECRIS for the production of intense metal ion beam ·····································
Y. Higurashi et al.

107

Beam energy adjuster for super-heavy element synthesis at RIKEN Ring Cyclotron ·············································
K. Yamada et al.

108

Operation of high-temperature oven for 28-GHz superconducting ECR ion source···············································
J. Ohnishi et al.

109

Laser Energy Dependence of Plasma Instability by Solenoid Magnetic Field ·····················································
T. Karino et al.

110

Evaluation of beam orbit calculation method for the injection line of AVF cyclotron and performance evaluationof pepper-pot emittance monitor····································································································
Y. Kotaka et al.

111

Updating control units around the AVF cyclotron ······················································································
M. Komiyama et al.

112

Reconstruction of RF system controller for RIKEN Ring Cyclotron ································································
K. Yamada et al.

113

Radiation monitoring for cycrotrons in RIBF ···························································································
M. Nakamura et al.

114

Development of beam interlock system driven by change in current of the magnet ··············································
K. Kumagai and A. Uchiyama

115

Design of reliable control with star-topology fieldbus communication for an electron cyclotron resonance ion source
at RIBF·································································································································
A. Uchiyama

116

Operation report for Nishina and RIBF water-cooling systems ······································································
T. Maie et al.

117

Pressure measurement of plasma window with large diameter ·······································································
N. Ikoma et al.

118

Maintenance of vacuum conditions of RILAC ·························································································
S. Watanabe et al.

119

9. Instrumentation
Application of the Generic Electronics for Time Projection Chamber (GET) readout system
for heavy radioactive isotope collision experiments·············································································
T. Isobe et al.

121

PANDORA, a large volume low-energy neutron detector with real-time neutron-gamma discrimination······················
L. Stuhl et al.

122

Measurement of total kinetic energy using LaBr3(Ce) crystal in ZeroDegree spectrometer for two-step experiment·········
H. Suzuki et al.

123

Prototype of new delay line with chip inductors for the PPAC ·······································································
H. Sato et al.

124

Development of electronics to allow vertex determination in the KISS MSPGC ··················································
P. Schury et al.

125

RIKEN Accel. Prog. Rep. 52 (2019)

CONTENTS

Development of Plastic Scintillator Barrel for WASA at GSI ········································································
R. Sekiya et al.

126

Energy dependence study of cylindrical drift chamber used for the MTV experiment············································
F. Goto et al.

127

Development of long and high-density data bus for sPHENIX INTT detector ·····················································
T. Hachiya et al.

128

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

129

Slit system between the foci F2 and F3 of the BigRIPS separator ···································································
K. Yoshida et al.

130

Fast beam interlock system for BigRIPS separator ····················································································
K. Yoshida

131

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

132

Primary beam intensity calibration method using charge-states distribution ·······················································
D. S. Ahn et al.

133

Angle-tunable degrader system for OEDO ······························································································
J. W. Hwang et al.

134

Development of dispersion-matching optics of primary beam for SRC-BigRIPS system ········································S. Y. Matsumoto et al.

135

SHE-Mass-II: an MRTOF-MS for Super Heavy Nuclei ···············································································
M. Wada et al.

136

Status and future plans of the MRTOF MS constructed at the SLOWRI facility···················································
M. Rosenbusch et al.

137

Development of multiple reflection time of flight mass spectrograph at KISS ·····················································J. Y. Moon et al.

138

Offline test for RF carpet transportation in RF ion guide gas cell at the SLOWRI facility ·······································
A. Takamine et al.

139

Study of extraction yield of multi-nucleon transfer reaction products by using cooled argon gas cell ··························
Y. Hirayama et al.

140

Yield analysis using target sliding system at KISS ·····················································································Y. X. Watanabe et al.

141

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

142

Electron-beam-current control at RTM injector ························································································
M. Watanabe et al.

143

Modification of dc-to-pulse converter FRAC ···························································································
S. Sato et al.

144

Precise magnetic field measurement of WiSES ·························································································
H. Wauke et al.

145

MPV – Parallel Readout Extension of VME ····························································································
H. Baba et al.

146

Validation method to merge digital data acquisition with analog data-acquisition system in SAMURAI30 experiment·····
J. Gao, L. Stuhl

147

Development of 1.5-mm thick liquid hydrogen target ·················································································
S. Koyama and D. Suzuki

148

Profile measurement of a large target cell of liquid hydrogen ········································································
M. Miwa et al.

149

The stability of the liquid hydrogen target system during the SAMURAI 30 experiment ········································
X. Sun et al.

150

Design of an Ion Source for the eSHE project Toward Pioneering Electron Scattering on Superheavy Elements ············S. Naimi

151

Absolute optical absorption cross-section of Rb atoms injected into superfluid helium using energetic ion beams···········
K. Imamura et al.

152

CONTENTS

RIKEN Accel. Prog. Rep. 52 (2019)Baseline correction system of laser-microwave double resonance spectrum for atoms injected into superfluid heliumby laser sputtering ····················································································································
M. Sanjo et al.

153

Attempt to measure relaxation time of atomic bubble surrounding alkaline atoms in superfluid helium ·······················Y. Takeuchi et al.

154

Development of offline ion source for collinear laser spectroscopy of RI beams ··················································
M. Tajima et al.

155

Development of active nuclear spin maser with time-separated feedback scheme for Xe-EDM search ························
T. Sato et al.

156

Epithermal neutron spin filter with dynamic nuclear polarization using photo-excited triplet electron ·························S. Takada et al.

157

Measurement of impurity nuclides in 10.75 MeV/nucleon 136Xe beam in the atmosphere ·······································
T. Kambara and A. Yoshida

158

Computing and network environment at the RIKEN Nishina Center ·······························································
T. Ichihara et al.

159

CCJ operations in 2018 ····················································································································
S. Yokkaichi et al.

160

Ⅲ. RESEARCH ACTIVITIES II (Material Science and Biology)

1. Atomic and Solid State Physics (Ion)
Effects of asymmetrically-introduced splayed columnar defects on the peak effect in (Ba, K)Fe2As2 ··························
T. Tamegai et al.

161

Control of the electrical conductivity in diamond by ion implantation ······························································
H. Yamazaki et al.

162

Investigation of single event effects observed in SiC-SBDs ··········································································
Y. Nakada et al.

163

Energy dependence of MeV-ion microbeam size extracted from tapered glass capillary optics ·································
M. Ikekame et al.

164

Development of UV microbeam irradiation system by glass capillary optics ······················································
S. Kawamura et al.

165

2. Atomic and Solid State Physics (Muon)
Magnetic ordered states of hole-doped pyrochlore iridates (Y1-x-yCuxCay)2Ir2O7 investigated by μ SR ··························
J. Angel et al.

167

Generalization of muon spin relaxation function to study the pseudogap state of the underdoped La2-xSrxCuO4 ·············
M. D. Umar and I. Watanabe

168

Magnetic order in defective reduced graphene oxides (rGO) investigated using μ SR·············································
R. Asih et al.

169

Ground state of quasi-one dimensional competing spin chain Cs2Cu2Mo3O12 ······················································
T. Goto and K. Matsui

170Superconductivity in single crystals of λ-(BETS)2GaCl4 studied by transverse-field μ SR········································
D. P. Sari et al.

171

μ SR study on ferrimagnetism of Na-K alloy clusters incorporated into zeolite LSX under high-pressure helium gas ·······
T. Nakano et al.

172

Quantum effects of muon on the electronic state of La2CuO4 ·········································································
M. R. Ramadhan et al.

173

Ab-initio calculation and μ SR study of the covalency effect in YBa2Cu3O6 ························································
I. Ramli et al.

174

Studies of electrical conductivity in 12-mer single-stranded DNA by using scanning tunneling microscope ·················
H. Rozak et al.

175

Magnetic ordering of (Eu1-xCax)2Ir2O7 studied using muon spin relaxation (μ SR) ·················································
U. Widyaiswari et al.

176

μ SR study of the Cu-spin correlation in the electron-underdoped Pr1.3-xLa0.7CexCuO4+δ (x = 0.05) single crystals ············
T. Adachi et al.

177

RIKEN Accel. Prog. Rep. 52 (2019)

CONTENTS

Reduction in Néel Temperature of La2CuO4 Nanoparticles ···········································································
S. Winarsih et al.

178

Muon spin relaxation after hydrogen absorption-desorption process in Pd ·························································
M. Mihara et al.

179

Negative muon spin rotation with low-density gas target under transverse magnetic field
to solve the proton radius puzzle ···································································································
S. Kanda et al.
Measurement of total muonium emission yield from silica aerogel using μ SR method ··········································
K. Ishida et al.

180
181

3. Radiochemistry and Nuclear Chemistry
Extraction behavior of rutherfordium as a cationic fluoride complex with a TTA chelate extractant
from HF/HNO3 acidic solutions ····································································································
A. Yokoyama et al.

183

Coprecipitation experiment of element 102, No, with Sm(OH)3 using NH3 and NaOH solution ································
H. Ninomiya et al.

184

Complex formation of Fr with crown ethers ····························································································
Y. Komori et al.

185

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

186

Study of anion exchange equilibrium of Zr and Hf in H2SO4 for Rf experiment ··················································
T. Yokokita et al.

187

Development of 211At-labeled antibody for targeted alpha therapy···································································
Y. Kanayama et al.

188

RI imaging tracers for Na+/K+ dynamics in a living body ·············································································S. Motomura et al.

189

Measurement of activation cross sections of alpha particle induced reactions on iridium up to an energy of 50 MeV·······S. Takács et al.

190

Cross-section measurement of α -induced reactions on natEr for 169Yb production ·················································
M. Saito et al.

191

Activation cross sections of alpha-induced reactions on natIn for 117mSn production ···············································
M. Aikawa et al.

192

Investigation of alpha particle induced reactions on natural silver in the 40–50 MeV energy range ····························
F. Ditrói et al.

193

Production cross sections of deuteron-induced reactions on natural palladium for Ag isotopes ·································
N. Ukon et al.

194

Production cross sections of 111Ag in deuteron-induced nuclear reactions on natural palladium ································
K. Ooe et al.

195

Production cross sections of Mo, Nb and Zr radioisotopes from α -induced reaction on natZr ····································
T. Murata et al.

196

Activation cross sections of deuteron-induced reactions on niobium up to 24 MeV ··············································
M. Aikawa et al.

197

New cross section data for production of zirconium-89 by alpha-induced reaction on yttrium target ··························
T. Murata et al.

198

Cross section measurement of the deuteron-induced reaction on 89Y to produce 89Zr ·············································
M. Sakaguchi et al.

199

Activation cross sections of alpha particle induced reactions on natural nickel up to 50 MeV ··································S. Takács et al.

200

Measurement of half-lives of 181, 182a, 182b, 183, 184mRe and 187W ···········································································
Y. Komori and H. Haba

201

Production of Np isotopes in nuclear reactions for standard material in accelerator mass spectrometry ·······················
Y. Hayakawa et al.

202

Column chromatography of astatine using weak base anion exchange resin ·······················································
H. Ikeda et al.

203

CONTENTS

RIKEN Accel. Prog. Rep. 52 (2019)

Speciation analysis of oxidation states of astatine extracted into ethanol-water solutions ········································
Y. Shin et al.

204

Purification of 121mTe by anion exchange chromatography ············································································
T. Kubota et al.

205

Production of arsenic RI tracer from gallium oxide target by alpha beam irradiation ·············································
H. Ikeda et al.

206

Production of 44mSc for multiple-isotope PET ···························································································
T. Fukuchi et al.

207

Adsorption experiments of 88Y and 143Pm on in HNO3 ·················································································
T. Yokokita et al.

208

4. Radiation Chemistry and Biology
Development of new cultivar of Hibiscus by C-ion beam irradiation ·······························································S. Ochiai et al.

209

Effect of heavy ion beam irradiation on germination and mutation rate in local Toraja rice ·····································
R. Sjahril et al.

210

Isolation of the chalky grain mutant 13–45 in rice (Oryza sativa L.) ································································
T. Katsube-Tanaka et al.

211

Molecular analysis of the stay-green mutant dye1 induced by carbon ion beams in rice ·········································
H. Yamatani et al.

212

An early-flowering einkorn wheat mutant with deletions of PHYTOCLOCK 1/LUX ARRHYTHMO and VERNALIZATION 2
exhibits a high level of VERNALIZATION 1 expression induced by vernalization ················································ 213
K. Murai et al.
Effects of carbon-ion irradiation to male gametes on double fertilization in Cyrtanthus mackenii ······························
T. Hirano et al.

214

Death of pollen tetrads caused by chromosomal rearrangement ·····································································
Y. Kazama et al.

215

Estimation of efficient dose for heavy-ion beam mutagenesis by whole-genome mutational analysis
in Arabidopsis thaliana ··············································································································
K. Ishii et al.

216

Characterization of L-cysteine requiring mutants derived from heavy-ion-beam irradiated cells
in the unicellular green alga Parachlorella kessleri ·············································································
T. Yamazaki et al.

217

Increase of lipid production upon outdoor cultivation of heavy-ion beam irradiation mutant Parachlorella kessleri PK4and identification of its genetic variations ························································································
T. Takeshita et al.

218

Pleiotropic mutant of plant-symbiotic edible mushroom Tricholoma matsutake induced by argon-ion beam ·················
H. Murata et al.
Comparison of biological effect between low- and high-LET irradiation on DSB repair
in the filamentous fungus Neurospora crassa ····················································································
L. Ma et al.

219

220

Effect of different conditions of the mutant isolation system on rotifers by using heavy-ion beam irradiation ···············
K. Tsuneizumi et al.

221

The inhibitor of DNA-PK suppressed DNA repair after heavy-ion irradiation in quiescent mammalian cells ················
M. Izumi and T. Abe

222

Phosphorylation and accumulation of low-dose high-LET heavy ion-induced bystander signaling molecules ···············
M. Tomita et al.

223

CR-39 imaging method to estimate microbeam profiles produced by tapered glass capillary optics ···························
Y. Hikima et al.

224

Stability test of ion microbeams produced by tapered glass capillary optics for biological use ·································
T. Ikeda et al.

225

Ⅳ. OPERATION RECORDS
Program Advisory Committee meetings for nuclear physics and for materials and life experiments ···························
K. Yoneda et al.

227

RIKEN Accel. Prog. Rep. 52 (2019)

CONTENTS

Beam-time statistics of RIBF experiments ······························································································
K. Yoneda and H. Ueno

228

Electric power consumption of RIKEN Nishina Center in 2018 ·····································································
E. Ikezawa et al.

229

Operation report of the ring cyclotrons in the RIBF accelerator complex ··························································
J. Shibata et al.

230

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

231

Operation report on the RIKEN AVF cyclotron for 2018 ·············································································
K. Kobayashi et al.

232

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

233

Present status of the BigRIPS cryogenic plant···························································································
K. Kusaka et al.

234

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

235

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

237

Fee-based activities by the industrial application research team ·····································································
A. Yoshida et al.

238

Ⅴ. EVENTS
DIS2018 International Workshop ·········································································································
Y. Goto, for the QNP2018 LOC

239

RIKEN Open Day 2018 ····················································································································
K. Yoshida and T. Uesaka

240

Workshop on “The r-process and unstable nuclei in multi-messenger astronomy”················································
N. Nishimura et al.

241

TESLA Technology Collaboration Meeting 2019 at RIKEN Nishina Center ······················································
N. Sakamoto

242

Participation in Hokkaido Science Festival ·····························································································
N. Miyauchi

243

QNP2018 International Conference ······································································································
Y. Goto, for the QNP2018 LOC

244

RIBF “Hodan-kai” meeting on the future of exotic nuclear physics ·································································
T. Matsumoto

245

Symposium on “Science and Technology Explored with Periodic Table” celebrating the “IYPT2019 in Japan” ·············
H. Sakurai

246

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

247

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

248

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

248

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

249

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

250

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

253

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

255

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

256

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

258

CONTENTS

RIKEN Accel. Prog. Rep. 52 (2019)

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

267

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

273

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

278

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

283

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

285

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

289

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

291

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

294

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

296

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

298

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

299

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

302

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

303

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

304

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

305

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

307

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

309

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

310

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

311

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

313

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

315

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

316

Instrumentation Development Group ······························································································317

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

319

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

323

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

325

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

328

BigRIPS Team ·················································································································

329

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

332

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

335

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

337

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

340

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

341

Plant Genome Evolution Research Team ···················································································345

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

347

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

348

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

355

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

357

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

362

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

365

Meson Science Laboratory ··········································································································369

RIKEN Accel. Prog. Rep. 52 (2019)

CONTENTSRIKEN BNL Research Center ······································································································

375

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

376

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

378

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

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

389

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

394

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

396

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

397

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

398

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) ································································

411

Events (April 2018 – March 2019) ·······································································································

414

Press Releases (April 2018 – March 2019) ······························································································

415

Ⅶ. LIST OF PREPRINTS
List of Preprints (April 2018 – March 2019) ····························································································

417

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS
List of Symposia & Workshops (April 2018 – March 2019) ··········································································

419

List of Seminars (April 2018 – March 2019) ···························································································

419

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. 52 (2019)

First observation of 20 B and 21 B†
S. Leblond,∗1 F. M. Marqués,∗1 J. Gibelin,∗1 N. A. Orr,∗1 Y. Kondo,∗2 T. Nakamura,∗2 J. Bonnard,∗3
N. Michel,∗4,∗5 N. L. Achouri,∗1 T. Aumann,∗6,∗7 H. Baba,∗8 F. Delaunay,∗1 Q. Deshayes,∗1 P. Doornenbal,∗8
N. Fukuda,∗8 J. W. Hwang,∗9 N. Inabe,∗8 T. Isobe,∗8 D. Kameda,∗8 D. Kanno,∗2 S. Kim,∗9 N. Kobayashi,∗2
T. Kobayashi,∗10 T. Kubo,∗8 J. Lee,∗8 R. Minakata,∗2 T. Motobayashi,∗8 D. Murai,∗11 T. Murakami,∗12
K. Muto,∗10 T. Nakashima,∗2 N. Nakatsuka,∗12 A. Navin,∗13 S. Nishi,∗2 S. Ogoshi,∗2 H. Otsu,∗8 H. Sato,∗8
Y. Satou,∗9 Y. Shimizu,∗8 H. Suzuki,∗8 K. Takahashi,∗10 H. Takeda,∗8 S. Takeuchi,∗8 R. Tanaka,∗2
Y. Togano,∗2,∗7 A. G. Tuﬀ,∗14 M. Vandebrouck,∗3 and K. Yoneda∗835

It is well established that the shell structure of thenucleus, that leads to an enhanced stability for systems
with “magic” numbers of protons (Z) and/or neutrons(N ) of 2, 8, 20... is modiﬁed as the limits of particle stability, or driplines, are approached. Neutron numbers
between 8 and 20 correspond to the ﬁlling of the sdshell neutron single-particle orbitals. Approaching the
driplines, the energies of these orbitals evolve, leadingfor example to the disappearance of the N = 20 magic
number for Z = 10–12 and to the appearance of newshell closures at N = 14, 16 in the oxygen isotopes.
In this respect, the most neutron-rich boron isotopes,
which lie below doubly-magic 22, 24 O and straddle theneutron dripline, are of considerable interest.
After removing one or two nucleons from secondary
beams of 22 N and 22 C, produced at the RIBF of the
RIKEN Nishina Center, with a carbon reaction target, beam-velocity 19 B fragments and neutrons weredetected in the forward direction using the SAMURAI setup including the NEBULA neutron array.
The relative energy between the 19 B fragment andthe ﬁrst detected neutron is shown in Fig. 1. A
prominent resonance-like structure was observed atabout 2.5 MeV above the one-neutron decay threshold (Fig. 1) that, guided by theoretical considerations, has been identiﬁed as the 1− , 2− ground-state
doublet of 20 B, with energies Er = 1.56 ± 0.15 and2.50 ± 0.09 MeV. A weaker higher-lying peak was also
observed at 4.86 ± 0.25 MeV.
The data acquired for 21 B in the 19 B plus one(Fig. 1) and two-neutron channels were consistent withthe population of a resonance 2.47 ± 0.19 MeV above

25
20

22

O

23

O

24

21

N

22

N

23

20

C

19

B

O
N

22

C

15

N = 16

N [counts / 200 keV]

30

10
5
0

0

1

2

3

19

4

5

6

7

8

9

Erel( B+n) [MeV]Fig. 1. Relative energy spectrum of 19 B+n events following proton-removal from 22 N (gray) and 22 C (hatchedhistogram). The gray dotted line in the inset delineates
the neutron dripline.

the two-neutron emission threshold, and thus tentatively assigned to be the expected 3/2− ground state.
These results allowed the ﬁrst determinations to bemade of the ground-state masses of 20, 21 B, which arein agreement with the extrapolations of the most recent atomic-mass evaluations taking into account the19
B, 22 C and 23 N mass measurements. In this spirit,
the present 20, 21 B masses will permit mass-surface extrapolations in this region to be made with improved
precision and further from stability. In addition, 21 B
was found to exhibit direct two-neutron decay.
The identiﬁcation and ﬁrst spectroscopy of 20, 21 B
opens the way to the exploration of structure and correlations beyond the dripline below 24 O. In particular,
improvements in secondary-beam intensities and neutron detection should permit n-n correlations in the
decay of 21 B to be investigated and its ﬁrst excitedstate to be located. This, coupled with work underway
to investigate the excited states of 22 C, will provide direct insights into the N = 16 shell closure beyond theneutron dripline as well as stringent tests of a new generation of ab initio and related theoretical models.

†Condensed from the article in Phys. Rev. Lett. 121, 262502(2018), see also references therein.
∗1 LPC-Caen∗2 Department of Physics, Tokyo Institute of Technology∗3 Institut de Physique Nucléaire, Orsay∗4 NSCL/FRIB Laboratory, Michigan State University∗5 School of Physics, Peking University∗6 Institut für Kernphysik, Technische Universität Darmstadt∗7 ExtreMe Matter Institute EMMI, GSI∗8 RIKEN Nishina Center∗9 Department of Physics and Astronomy, Seoul National University∗10 Department of Physics, Tohoku University∗11 Department of Physics, Rikkyo University∗12 Department of Physics, Kyoto University∗13 GANIL, CEA/DRF-CNRS/IN2P3∗14 Department of Physics, University of York-1-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Gamow–Teller giant resonance in 132 Sn
M. Sasano,∗1 J. Yasuda,∗2 L. Stuhl,∗1,∗6 R. G. T. Zegers,∗3 H. Baba,∗1 W. Chao,∗1 M. Dozono,∗1 N. Fukuda,∗1
N. Inabe,∗1 T. Isobe,∗1 G. Jhang,∗1,∗13 D. Kamaeda,∗1 T. Kubo,∗1 M. Kurata-Nishimura,∗1 E. Milman,∗1
T. Motobayashi,∗1 H. Otsu,∗1 V. Panin,∗1 W. Powell,∗1 M. Sako,∗1 H. Sato,∗1 Y. Shimizu,∗1 H. Suzuki,∗1
T. Suwat,∗1 H. Takeda,∗1 T. Uesaka,∗1 K. Yoneda,∗1 J. Zenihiro,∗1 T. Kobayashi,∗1,∗4 T. Sumikama,∗1,∗4
T. Tako,∗4 T. Nakamura,∗5 Y. Kondo,∗5 Y. Togano,∗5 M. Shikata,∗5 J. Tsubota,∗5 K. Yako,∗6 S. Shimoura,∗6
S. Ota,∗6 S. Kawase,∗6 Y. Kubota,∗6 M. Takaki,∗6 S. Michimasa,∗6 K. Kisamori,∗6 C. S. Lee,∗6 H. Tokieda,∗6
M. Kobayashi,∗6 S. Koyama,∗7 N. Kobayashi,∗7 H. Sakai,∗1 T. Wakasa,∗2 S. Sakaguchi,∗2 A. Krasznahorkay,∗8
T. Murakami,∗9 N. Nakatsuka,∗9 M. Kaneko,∗9 Y. Matsuda,∗10 D. Mucher,∗11 S. Reichert,∗11 D. Bazin,∗3
and J. W. Lee∗12
Among collective modes,1) the Gamow-Teller (GT)
giant resonance is an interesting excitation mode. It
is a 0h̄ω excitation characterized by the quantumnumber changes in orbital angular momentum (∆L =0), spin (∆S = 1), and isospin (∆T = 1), and it isinduced by the transition operator στ . In stable nuclei
in medium or heavier mass regions (A > 50), the collectivity in this mode exhibits the GT giant resonance(GTGR), which provides information that is criticallyimportant for understanding the isovector part of theeﬀective nucleon-nucleon interaction2) and the symmetry potential of the equation of state.3) In particular,
the understanding of the short-range repulsive part ofthe eﬀective interaction, i.e., so-called Landau-Migdal(LM) force in the spin-isospin channel, is crucial in
the prediction of the onset of the pion condensationin nuclear matters such as a neutron star.4) Recently,
we have been rapidly expanding the domain of GTGR
studies at RIBF in the nuclear chart.5,6) This provides
a new opportunity to evaluate the strength of the LM
force and the so-called LM parameter g ′ for an unstable nucleus.
In this study, an experiment at RIBF was performed
in March 2014 to extract the GT transition strengths
over a wide excitation energy range covering their giant resonances on the key doubly magic nucleus 132 Sn.
The purpose of the experiment was to calibrate theg ′ parameter through observating the GTGR in 132 Sn.
This is also an essential step toward establishing thecomprehensive theoretical models for the nuclei locatedbetween 78 Ni and 208 Pb. Details of the experimental setups and analysis are already given in previous
progress reports and the results have been recently
published in Ref. 7). Data for the GTGR were ob-tained almost in the same quality as the stable-beamexperiments, which opens up a new age of GR studies with RI beams in the ﬁeld of experimental nuclear
physics. The obtained g ′ parameter was 0.68 ± 0.07.
In comparison to the values obtained for the stable
nuclei 90 Zr and 208 Pb, it indicates that g ′ is kept almost constant over a region of isospin asymmetry from(N − Z)/A = 0.11 to 0.24 and from mass number
A = 90 to 208. It also indicates that pion condensation occurs in the inner part of a neutron star whosemass is 1.4 times heavier than the solar mass.
We are grateful to the RIKEN RIBF accelerator
crew and CNS, University of Tokyo, for their eﬀorts
and support to operate the RI beam factory. We
thank M. Ichimura, E. Litvinova, C. Robin, Y. F. Niu,
G. Colo, H. Z. Liang, and Z. M. Niu for our valuable
discussions. This work was supported in part by aGrant-in-Aid for Scientiﬁc Research (No. 274740187),
Grant-in-Aid for the Japan Society for the Promotionof Science (JSPS) Research Fellow (No. 265720), JSPS
KAKENHI Grant No. 16H02179 from the Japan Society for the Promotion of Science, MEXT KAKENHI
Grant No. 24105005, US NSF PHY-1430152 (JINA
Center for 606 the Evolution of the Elements), US NSF
PHY-1565546, and the Hungarian NKFI Foundation[K124810].
References
1) M. N. Harakeh, A. M. van der Woude, Giant Resonances (Oxford University Press, Oxford, 2001).
2) S. Fracasso, G. Colo, Phys. Rev. C 72, 064310 (2005).
3) P. Danielewicz, Nucl. Phys. A 727, 233 (2003).
4) A. B. Migdal, Rev. Mod. Phys. 50, 107 (1978).
5) M. Sasano et al., Phys. Rev. Lett. 107, 202501 (2011).
6) M. Sasano et al., Phys. Rev. C 86, 034324 (2012).
7) M. Sasano et al., Phys. Rev. Lett. 121, 132501 (2018).

∗1

RIKEN Nishina Center
Department of Physics,Kyushu University∗3 NSCL, Michigan State University∗4 Department of Physics, Tohoku University∗5 Department of Physics, Tokyo Institute of Technology∗6 CNS, University of Tokyo∗7 Department of Physics, University of Tokyo∗8 MTA, Atomki∗9 Department of Physics, Kyoto University∗10 Department of Physics, Konan University∗11 Department of Physics, Technical University Munich∗12 Department of Physics, Korea University∗2-2-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

First spectroscopy of the near drip-line nucleus 40 Mg†
H. L. Crawford,∗1 P. Fallon,∗1 A. O. Macchiavelli,∗1 P. Doornenbal,∗2 N. Aoi,∗3 F. Browne,∗2 C. M. Campbell,∗1
S. Chen,∗2 R. M. Clark,∗1 M. L. Cortés,∗2 M. Cromaz,∗1 E. Ideguchi,∗3 M. D. Jones,∗1 R. Kanungo,∗4,∗5
M. MacCormick,∗6 S. Momiyama,∗7 I. Murray,∗6 M. Niikura,∗7 S. Paschalis,∗8 M. Petri,∗8 H. Sakurai,∗2,∗7
M. Salathe,∗1 P. Schrock,∗9 D. Steppenbeck,∗9 S. Takeuchi,∗2,∗10 Y. K. Tanaka,∗11 R. Taniuchi,∗7 H. Wang,∗2 and
K. Wimmer∗7
Magnesium isotopes oﬀer an opportunity to experimentally study the transition from well-bound to
weakly-bound nuclei and its inﬂuence on the excitedstates, which may reﬂect the correlations at the limits of stability. While knowledge on the heaviest Mg
isotopes is limited, an overall consistent picture of thestructure along Z = 12 has emerged between N = 20
and N = 28, of persistent prolate deformation from32
Mg to 38 Mg,1) which likely extends to 40 Mg.2)
40
Mg represents a particularly intriguing case forstudy. Theoretical expectations and experimental systematics suggest 40 Mg to be a well-deformed prolate
rotor as well, structurally very similar to 36, 38 Mg. However, the occupation of the relatively weakly-bound
2p3/2 neutron orbital near the Fermi surface may add
a new degree of freedom. In this report, the ﬁrst γray spectroscopic information of 40 Mg is presented anddiscussed in the context of the systematics along themagnesium isotopes.
Experimentally, a drastically diﬀerent prompt γ-ray
spectrum is observed for 40 Mg (see Fig. 1 (c)) as compared to 36, 38 Mg (see Fig. 1 (a), (b)), contrary to expec+
tations. The tentatively assigned 2+
1 →01 transition at
38
500(14) keV is 20% below that in Mg, a trend that is
outside the shell-model and other state-of-the-art theoretical predictions. The second γ-ray transition is evenmore puzzling. Given that 40 Mg is very near the neutron dripline, and the low-ℓ ν2p3/2 orbital sits at the
Fermi surface, the observed spectrum may be an indication of the manifestation of weak-binding eﬀects, as
discussed fully in the published Letter.
The experiment was carried out at the Radioactive
Isotope Beam Factory (RIBF) at RIKEN Nishina Center. An intense (450 pnA) primary beam of 48 Ca wasfragmented on a rotating production target, producing
a secondary cocktail beam centered on 41 Al. This beam
was transported through BigRIPS3) and was incident
upon a thick polyethylene secondary target at the focal

plane in front of ZeroDegree, which was tuned to center 40 Mg reaction residues. Prompt γ rays depopulating
the excited states in 40 Mg and other reaction residues
were detected in the DALI2 spectrometer,5) which consistisof 186 large-volume NaI(Tl) detectors surrounding
the secondary target.

(a) 36Mg from 40Al

659(6)

70
60
50

1319(21)

40
30
20
10
0

(b) 38Mg from 40Al

635(6)Counts / 25 keV

120
100

1332(19)

80
60
40
20

(c) 40Mg from 41Al
670(16)8500(14)

0

10

6
4
2
0
0

500

1000

1500

2000

2500

Energy [keV]

Fig. 1. (color online) Prompt γ-ray spectrum associatedwith (a) 36 Mg, (b) 38 Mg and (c) 40 Mg (populated in −1p
removal from 41 Al). Spectra were fit using the simulated
DALI2 response (red dashed curves) and a smooth background (dotted blue line); the solid black line represents
the total fit.

†

Condensed from the article in press in Phys. Rev. Lett. (2019)
NSD, Lawrence Berkeley National Laboratory∗2 RIKEN Nishina Center∗3 RCNP, Osaka University∗4 Astronomy & Physics Department, Saint Mary’s University∗5 TRIUMF∗6 Institut de Physique Nucléaire, IN2P3-CNRS, Université
Paris-Sud, Université Paris-Saclay∗7 Department of Physics, University of Tokyo∗8 Department of Physics, University of York
∗9 CNS, University of Tokyo, RIKEN Campus∗10 Department of Physics, Tokyo Institute of Technology∗11 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗1

References

1) P. Doornenbal et al., Phys. Rev. Lett. 111, 212502 (2013).
2) H. L. Crawford et al., Phys. Rev. C 89, 041303 (2014).
3) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 03C003(2012).
4) Y. Mizoi et al., RIKEN Accel. Prog. Rep. 38, 297 (2005).
5) S. Takeuchi et al., Nucl. Instrum. Methods Phys. Res. A
763, 596 (2014).

-3-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Interplay between nuclear shell evolution and shape deformation
revealed by magnetic moment of 75 Cu†
Y. Ichikawa,∗1 H. Nishibata,∗1,∗2 Y. Tsunoda,∗3 A. Takamine,∗1 K. Imamura,∗1,∗4 T. Fujita,∗1,∗2 T. Sato,∗1,∗5
S. Momiyama,∗6 Y. Shimizu,∗1 D. S. Ahn,∗1 K. Asahi,∗1,∗5 H. Baba,∗1 D. L. Balabanski,∗1,∗7 F. Boulay,∗1,∗8,∗9J. M. Daugas,∗1,∗9 T. Egami,∗10 N. Fukuda,∗1 C. Funayama,∗5 T. Furukawa,∗11 G. Georgiev,∗12
A. Gladkov,∗1,∗13 N. Inabe,∗1 Y. Ishibashi,∗1,∗14 T. Kawaguchi,∗10 T. Kawamura,∗2 Y. Kobayashi,∗1,∗15
S. Kojima,∗5 A. Kusoglu,∗7,∗12,∗16 I. Mukul,∗17 M. Niikura,∗6 T. Nishizaka,∗10 A. Odahara,∗2 Y. Ohtomo,∗1,∗5
T. Otsuka,∗1,∗3,∗6,∗18 D. Ralet,∗12 G. S. Simpson,∗19 T. Sumikama,∗1 H. Suzuki,∗1 H. Takeda,∗1 L. C. Tao,∗1,∗20
Y. Togano,∗1,∗5 D. Tominaga,∗10 H. Ueno,∗1 H. Yamazaki,∗1 and X. F. Yang∗18
3.0Magnetic moment [ μN ]Exotic nuclei are characterized by a number of excess
neutrons (or protons) relative to stable nuclei. Theirshell structure, which represents single-particle motion
in a nucleus, may vary owing to nuclear force andexcess neutrons, in a phenomenon called shell evolution. This eﬀect could be counterbalanced by collectivemodes causing deformations of the nuclear surface. We
studied the interplay between shell evolution and shapedeformation by focusing on the magnetic moment of
an isomeric state of the neutron-rich nucleus 75 Cu,1)
where low-lying states of the Cu isotopes exhibit an
intriguing behavior involving the shell evolution.2–4)
The magnetic moment measurement was carried out
at the BigRIPS at RIBF. Spin alignment as large as
30% was achieved in the isomeric state of 75 Cu by
a scheme of two-step projectile fragmentation with atechnique of momentum-dispersion matching,5) incorporating an angular-momentum selecting proton removal from 76 Zn. The magnetic moment was determined using the time-diﬀerential perturbed angular
distribution (TDPAD) method. Owing to the highspin alignment realized by the reﬁned two-step scheme,
the observed oscillation for the 66.2-keV γ rays in the
TDPAD spectrum had a signiﬁcance greater than 5σ.
The magnetic moment of the 66.2-keV isomer with spinparity 3/2− was determined to be µ = 1.40(6) µN for
the ﬁrst time.

μ(π p3/2)
3/2−

2.0

μ(π f5/2)

This work
1.0

0Exp. 3/2−
Exp. 5/2−
Calc. 3/2−
Calc. 5/2−

5/2−

69

Cu

71

Cu

Cu

73

75

Cu

Cu

77

79

Cu

Fig. 1. Systematics of magnetic moments for odd-A Cu
isotopes. Filled and open circles represent experimental
data for 3/2− and 5/2− states, respectively. Filled red
circle represents the result obtained in this work. Solidgreen and blue lines represent MCSM calculations for
3/2− and 5/2− states, respectively, with 20 ≤ (N, Z) ≤56 model space.6) µ(πp3/2 ) and µ(πf5/2 ) denote theproton Schmidt values for p3/2 and f5/2 , respectively.

The magnetic moment, thus obtained, demonstrated
a considerable deviation from the Schmidt value, µ =3.05 µN , for the p3/2 orbital. Figure 1 shows the systematics of magnetic moments of the 3/2− and 5/2−
states, where deviation from the Schmidt values appears to be maximal at 75 Cu. The analysis of themagnetic moment with the help of Monte Carlo shellmodel (MCSM) calculations6) reveals that the trendof the deviation corresponds to the eﬀect of core excitation and the low-lying states in 75 Cu are, to a large
extent, of a single-particle nature on top of a correlated 74 Ni core, elucidating the crucial role of the shellevolution even in the presence of collective mode.

†

Condensed from the letter in Nat. Phys. 15, 321 (2019)
RIKEN Nishina Center∗2 Department of Physics, Osaka University∗3 Center for Nuclear Study, University of Tokyo∗4 Department of Physics, Meiji University∗5 Department of Physics, Tokyo Institute of Technology∗6 Department of Physics, University of Tokyo∗7 ELI-NP, IFIN-HH∗8 GANIL, CEA/DSM-CNRS/IN2P3∗9 CEA, DAM, DIF∗10 Department of Advanced Sciences, Hosei University∗11 Department of Physics, Tokyo Metropolitan University∗12 CSNSM, CNRS/IN2P3, Université Pris-Sud∗13 Department of Physics, Kyungpook National University∗14 Department of Physics, University of Tsukuba∗15 Department of Informatics and Engineering, University ofElectro-Communications∗16 Department of Physics, Istanbul University∗17 Department of Particle Physics, Weizmann Institute∗18 Intsituut voor Kern-en Srralingsfysica, K. U. Leuven∗19 LPSC, Université Grenoble Alpes, CNRS/IN2P3∗20 School of Physics, Peking University∗1

References
1) C. Petrone et al., Phys. Rev. C 94, 024319 (2016).
2) T. Otsuka et al., Phys. Rev. Lett. 95, 232502 (2005).
3) S. Franchoo et al., Phys. Rev. Lett. 81, 3100 (1998).
4) K. T. Flanagan et al., Phys. Rev. Lett. 103, 142501(2009).
5) Y. Ichikawa et al., Nat. Phys. 8, 918 (2012).
6) Y. Tsunoda et al., Phys. Rev. C 89, 031301(R) (2014).

-4-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Mass measurements of neutron-rich Ni isotopes in Rare RI Ring
A. Ozawa,∗1 Y. Abe,∗2 D. Nagae,∗2 S. Naimi,∗2 F. Suzaki,∗2 Y. Yamaguchi,∗2 M. Wakasugi,∗2 H. Arakawa,∗3
S. Hosoi,∗3 Y. Inada,∗3 K. Inomata,∗3 T. Kobayayashi,∗3 K. Nishimuro,∗3 S. Omika,∗3 M. Sakaue,∗3 K. Yokota,∗3
T. Yamaguchi,∗3 R. Kagesawa,∗1 D. Kamioka,∗1 T. Moriguchi,∗1 M. Mukai,∗1 S. Ota,∗4 N. Kitamura,∗4
S. Masuoka,∗4 S. Michimasa,∗4 D. S. Ahn,∗1 H. Baba,∗1 N. Fukuda,∗1 Y. Shimizu,∗1 H. Suzuki,∗1 H. Takeda,∗1
Z. Ge,∗5 H. Li,∗5 S. Suzuki,∗5 K. Wang,∗5 Q. Wang,∗5 M. Wang,∗5 Y. Litvinov,∗6 Z. Podolyak,∗7 and T. Uesaka∗2
Nuclear mass measurements are important to investigate nuclear structure and pathway of nucleosynthesis. Neutron separation energies (Sn and S2n ), which
can be deduced from the nuclear masses, are very sensitive to the nuclear shell structure. In nucleosynthesis, Sn is a key parameter to determine the pathwayof the r-process. Ni isotopes have a magic number forthe protons (Z = 28) and three doubly magic isotopes(N = 20, 28, 50). Ni isotopes close to 78 Ni are assumed
to lie on the r-process path. Thus, the mass measurements for neutron-rich Ni isotopes are anticipated. Until
now, in neutron-rich Ni isotopes, masses up to 73 Ni havebeen evaluated in Atomic Mass Evaluation.1) The massof 74 Ni has been reported in Ref. 2). However, the error
bar is quite large (approximately 1 MeV). Thus, in thisexperiment, we performed the mass measurements forneutron-rich Ni isotopes (74, 76 Ni) in Rare RI Ring (R3).
The experimental setup in this measurement is essentially the same as that in the previous experimentat R3.3) We improved beam optics after installing the
OEDO system.4) The primary beam of 238 U accelerated
in SRC up to 345 MeV/nucleon was impinged on a Be
target. Secondary beams including 74, 76 Ni isotopes were
produced through in-flight reaction. We adjusted thethickness of the degraders located at F1 and F2 in BigRIPS such that the beam energies of 74, 76 Ni became
approximately 160 MeV/nucleon, which is the suitableenergy for individual ion injection.5)
Particle identification in BigRIPS was done by TOF
between F2 and F3, which were measured by two plastic scintillators, and ∆E at F3, that was measured byan ionization chamber (IC). In this experimental setting, a typical count rate for 76 Ni in F3 was approximately 0.16 cps for the full primary beam intensity(approximately 60 particles nA). The plastic scintillator at F3 also provided trigger signals for the kicker
magnets in R3. To maintain the trigger rate of the
kicker magnets within 100 Hz, we applied TOF-∆E
gates to the trigger signals, as described in Ref. 6).
A typical particle identification spectrum at F3 (forthe case of 74 Ni) is shown in Fig. 1. In this experiment, momentum dispersive focus was applied at F5in BigRIPS. We placed two PPACs there to measure
the momentum of the beams (Bρ). At S0, i.e., at
the entrance of SHARAQ, we located a TOF counter,
∗1
∗2
∗3
∗4
∗5
∗6
∗7

Fig. 1. A typical particle identification spectrum as measured at F3 for 74 Ni mass measurement.

which is a similar to the one used inside R3.7) ThisTOF counter provided a start signal to the TOF in R3.
We also measured the TOFs of each particle between
F3 and S0, which were converted to the β of their beams.
The particle injected into R3 was extracted after approximately 700 µs using the same kicker magnets. After the
extraction, the particle was collided with a plastic scintillator, which provided a stop signal for the TOF in R3
and IC. Finally, it was stopped in an NaI scintillator. In
the measurement of 74 Ni (76 Ni), the isochronous opticsof R3 were tuned using 76 Zn (78 Zn) such that the widthof TOF in R3 was the narrowest for this nucleus, thereby
resulting in a width of approximately 3 ps. Furthermore,
we carefully tuned the septum magnets and magnets at
the injection line of R3 to increase the transmission efficiencies of 74, 76 Ni from F3 to R3. The achieved values
for 74 Ni and 76 Ni were approximately 0.5% and 2.8%,
respectively. In this experiment, we accumulated theevents for 74 Ni (76 Ni) for approximately 5 h (10 h). To
deduce the masses, the TOF in R3 should be correctedby the corresponding β or Bρ. The analysis of data is
still ongoing.
References

1) M. Wang et al., Chin. Phys. 41, 030003 (2017).
2) A. Estrade et al., Phys. Rev. Lett. 107, 172503 (2011).
3) D. Nagae et al., RIKEN Accel. Prog. Rep. 50, 18 (2017).
4) Y. Yamaguchi et al., RIKEN Accel. Prog. Rep. 51, 165(2018).
5) Y. Yamaguchi et al., RIKEN Accel. Prog. Rep. 49, 18(2016).
6) Y. Abe et al., in this report.
7) D. Nagae et al., RIKEN Accel. Prog. Rep. 49, 181 (2016).

Institute of Physics, University of Tsukuba
RIKEN Nishina Center
Department of Physics, Saitama University
CNS, University of Tokyo
IMP, CAS, Lanzhou, China
GSI Helmholtz Center, Darmstadt, Germany
NPI, University of Surrey-5-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Discovery of 60 Ca and Implications For the Stability of 70 Ca†
O. B. Tarasov,∗1,∗2 D. S. Ahn,∗2 D. Bazin,∗1,∗2 N. Fukuda,∗2 A. Gade,∗1 M. Hausmann,∗1 N. Inabe,∗2
S. Ishikawa,∗3 N. Iwasa,∗3 K. Kawata,∗4 T. Komatsubara,∗2 T. Kubo,∗1,∗2 K. Kusaka,∗2 D. J. Morrissey,∗1,∗2
M. Ohtake,∗2 H. Otsu,∗2 M. Portillo,∗1,2 T. Sakakibara,∗3 H. Sakurai,∗2 H. Sato,∗2 B. M. Sherrill,∗1,∗2
Y. Shimizu,∗2 A. Stolz,∗1 T. Sumikama,∗2 H. Suzuki,∗2 H. Takeda,∗2 M. Thoennessen,∗1 H. Ueno,∗2
Y. Yanagisawa,∗2 and K. Yoshida∗2
The landscape of atomic nuclei is delineated by the
nucleon drip lines beyond which no bound states oflighter or heavier isotopes exist. The location of theneutron drip line provides a key benchmark for nuclear models and the quest to understand the nuclear
force. The proton-magic calcium isotopes span themagic neutron numbers 20, 28, 32, 34, and possibly
40 and 50. The calcium chain is just within reachof ab-initio models1) as well as the broadly applicablemean-ﬁeld and conﬁguration-interaction models. Observation of 59 Ca and 60 Ca would test the predictive
power of ab-initio models as compared to the energy
density functionals (EDFs), and indicate if the successof the ab-initio approaches in describing the masses of
the calcium isotopes. Measurements at NSCL2,3) havedemonstrated that the fragmentation of 76 Ge and 82 Se
beams using a two-stage separator can be used to produce new neutron-rich isotopes in the calcium region.
We report here the continuation of this work at the
RIKEN RIBF facility, using a higher beam energy andintensity, and so accessing the one-order-of-magnitude
lower production cross sections needed to explore thestability of 59, 60 Ca.
The discovery of 60
20 Ca40 and seven other neutronrich nuclei near the limits of stability is reported fromthe projectile fragmentation of 345 MeV/nucleon 70 Zn
beam with an intensity of 225 particle nA on Be targets
at the RI Beam Factory operated by RIKEN Nishina
Center and CNS, University of Tokyo. During a 99.5
hour measurement, 47 P, 49 S, 52 Cl, 54 Ar, 57 K, 59, 60 Ca,
and 62 Sc, the most neutron-rich isotopes of the respective elements, were observed for the ﬁrst time. In addition, one event consistent with 59 K was observed. The
produced fragments were analyzed and unambiguously
identiﬁed using the BigRIPS two-stage in-ﬂight separator tuned according to LISE++ calculations.4) Twoaluminum wedge-shaped degraders at the F1 and F5
dispersive planes were used at full BigRIPS momentum
acceptance to separate and purify the RI beams. The
particle identiﬁcation (PID) was conducted using the
ToF-Bρ-∆E-TKE method described in the appendix
to the previous work.5)
The results are compared with the drip-line predic†
∗1
∗2
∗3
∗4

Fig. 1. The region of the chart of nuclides studied in thiswork. Nuclei highlighted by red background were discovered in this work, green squares denote nuclei discovered at the NSCL since 2007.2,3,8,9) The neutron
drip lines predicted by the HFB-22,6) UNEDF1,10) and
WS4RBF 11) mass models are indicated by the blue dotted, red solid, and green dashed lines, respectively. The
model WS4RBF appears to underestimate the bindingsof isotopes in this region. HFB-22 and UNEDF1 seemto better predict the drip line. The inset shows thepredicted S2n values for even neutron-rich calcium isotopes.

tions of a wide variety of mass models. The two isotopes 49 S and 52 Cl, discovered in this work, emerge as
key discriminators between diﬀerent models. EDFs inbest agreement with the limits of existence in the explored region, HFB-226) and UNEDF0,7) predict theeven-mass Ca isotopes to be bound out to at least 70 Ca(see Fig. 1), at odds with ab-initio models that predict
the neutron drip line in Ca to be closer to 60 Ca with59
Ca unbound.
References

1) G. Hagen et al., Phys. Rev. Lett. 108, 242501 (2012).
2) O. B. Tarasov et al., Phys. Rev. Lett. 102, 142501(2009).
3) O. B. Tarasov et al., Phys. Rev. C 87, 054612 (2013).
4) O. B. Tarasov, D. Bazin, Nucl. Instrum. Methods Phys.
Res. B 266, 4657 (2008), http://lise.nscl.msu.edu .
5) O. B. Tarasov et al., Phys. Rev. C 80, 034609 (2009).
6) S. Goriely et al., Phys. Rev. C 88, 024308 (2013).
7) M. Kortelainen et al., Phys. Rev. C 82, 024313 (2010).
8) O. B. Tarasov et al., Phys. Rev. C 75, 064613 (2007).
9) T. Baumann et al., Nature 449, 1022 (2007).
10) M. Kortelainen et al., Phys. Rev. C 85, 024304 (2012).
11) N. Wang et al., Phys. Lett. B 734, 215 (2014).

Condensed from the article in Phys. Rev. Lett. 121, 022501(2018)
NSCL/FRIB, Michigan State University
RIKEN Nishina Center
Department of Physics, Tohoku University
Center for Nuclear Study, University of Tokyo-6-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Nuclear surface diﬀuseness revealed in nucleon-nucleus diﬀraction†
S. Hatakeyama,∗1 W. Horiuchi,∗1 and A. Kohama∗2
A systematic study of the nuclear surface density ofneutron-rich nuclei is interesting, as it reveals the neutron number dependence of the nuclear structure dominated by nuclear dynamics at around the nuclear surface. The study can also be extended to understand theproperties of the equation of state of asymmetric nuclear
matter. However, it is diﬃcult to probe the neutron
density by using traditional electron scattering. In thispaper, we use a proton target as a probe of the surface
density. Extended systematic studies have shown that
it is advantageous to use proton to study the neutron
and proton radii because it has more sensitivity to theneutrons at low-incident energy.1,2) To know more than
the nuclear radii, we study the proton-nucleus elastic
scattering, focusing on the reactions of small scattering
angles up to a few diﬀraction peaks.
Here, we employ the optical-limit approximation of
the Glauber model. As the input to the theory, a twoparameter Fermi (2 pF) density, ρ(r) = 1+expρ0 r−R , is
( a )assumed. The parameter R is chosen to give the sameroot-mean-square (rms) radius with several choices ofa. By calculating diﬀerential elastic scattering cross sections (DECS), it is found that the ﬁrst peak position
does not change and that its magnitude increases withsmaller diﬀuseness (sharper surface). The magnitude of
the DECS at the ﬁrst peak position must have information on the nuclear surface.
We perform a “numerical experiment” to deduce thenuclear “diﬀuseness” from the reaction data. We havethe DECS obtained from the realistic densities, theSkyrme-Hartree-Fock (HF) + BCS method used inRefs. 2) and 3). Regarding the DECS used as experimental data, we determine R and a in such a way thatthe DECS with the 2 pF density matches the ﬁrst peak
position and its magnitude of the DECS obtained by
the HF+BCS density. The extracted a values are displayed in Fig. 1. We can clearly see the isotope dependence of the nuclear surface, indicating shell evolution,
weak binding, and nuclear deformation, which cruciallychange the density proﬁle at around the nuclear surface.3) We ﬁnd that the extracted a values have a robust
structure information that is independent of the choiceof the incident energy.
To extract detailed structure information of unstable
nuclei, separation of proton and neutron diﬀuseness isimportant because neutron diﬀuseness is expected to be
more sensitive to the ground-state structure of neutronrich isotopes as it is dominated by the neutron motion
at the nuclear surface. We investigate the possibility ofutilizing the incident energy dependence of the nucleonnucleon total cross sections.1,2) Again, we perform a nu†

∗1
∗2

0.65

a (fm)

0.6
0.55

Ca
Ni
Zr
Sn
Yb
Pb

0.5
0.45

20

40

60 80 100 120 140 160
Neutron number

Fig. 1. Nuclear “diﬀuseness” extracted from the “numericalexperiment” at an incident energy of 550 MeV.

merical experiment. We respectively assume 2 pF densities for protons and neutrons and determine these fourparameters to reproduce the ﬁrst peak positions andtheir DECS at low and high incident energies. We calculate the diﬀuseness parameters and rms radii of the
protons and neutrons for 120 Sn, 208 Pb, and neutron-rich132
Sn with several sets of two incident energies among
200, 300, 550, and 800 MeV. For 120 Sn and 208 Pb, theextracted diﬀuseness parameters are scattered around
0.4–0.6 fm depending on the incident energies chosen,though the rms radii are converged within ∼0.5%. In
such cases where the proton and neutron surfaces are located at almost the same position, the separation of the
proton and neutron surface proﬁles might be diﬃcult,whereas in the case of 132 Sn, all the extracted values are
consistent with each other within 0.003 fm for protons
and neutrons.
In summary, we have performed a numerical experiment using the theoretically obtained DECS of highenergy nucleon-nucleus scattering based on the Glaubermodel starting from the nucleon-nucleon total cross sections. We have shown that ﬁrst diﬀraction peak reﬂects
the nuclear density proﬁle at around the nuclear surface, and have proposed a way to quantify it with thediﬀuseness parameter of the 2 pF function, which can be
determined uniquely. This method is advantageous forapplication to studies of unstable nuclei since the experimental data is limited to forward angles in the inverse
kinematics. This can also be useful for extracting the information of the proton and neutron surfaces, although
the separation of the proton and neutron surfaces may
be possible only for such neutron (proton)-rich systems
in which the surfaces of the proton and neutron surfaces
are well separated.
References

1) W. Horiuchi et al., Phys. Rev. C 89, 011601(R) (2014).
2) W. Horiuchi et al., Phys. Rev. C 93, 044611 (2016).
3) W. Horiuchi et al., Phys. Rev. C 96, 035804 (2017).

Condensed from the article in Phys. Rev. C 97, 054607 (2018)
Department of Physics, Hokkaido University
RIKEN Nishina Center-7-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Proton- and deuteron-induced reactions on 107 Pd and 93 Zr
at 20–30 MeV/nucleon
M. Dozono,∗1 N. Imai,∗1 S. Michimasa,∗1 T. Sumikama,∗2 N. Chiga,∗2 S. Ota,∗1 O. Beliuskina,∗1 S. Hayakawa,∗1
K. Iribe,∗3 C. Iwamoto,∗1 S. Kawase,∗4 K. Kawata,∗1 N. Kitamura,∗1 S. Masuoka,∗1 K. Nakano,∗4 P. Schrock,∗1
D. Suzuki,∗2 R. Tsunoda,∗1 K. Wimmer,∗5 D. S. Ahn,∗2 N. Fukuda,∗2 E. Ideguchi,∗6 K. Kusaka,∗2 H. Miki,∗7
H. Miyatake,∗8 D. Nagae,∗2 M. Nakano,∗9 S. Ohmika,∗2 M. Ohtake,∗2 H. Otsu,∗2 H. J. Ong,∗6 S. Sato,∗9
H. Shimizu,∗1 Y. Shimizu,∗2 H. Sakurai,∗2 X. Sun,∗2 H. Suzuki,∗2 M. Takaki,∗1 H. Takeda,∗2 S. Takeuchi,∗7
T. Teranishi,∗3 H. Wang,∗2 Y. Watanabe,∗4 Y. X. Watanabe,∗8 H. Yamada,∗7 H. Yamaguchi,∗1 R. Yanagihara,∗6
L. Yang,∗1 Y. Yanagisawa,∗2 K. Yoshida,∗2 and S. Shimoura∗1
The nuclear transmutation of long-lived ﬁssion products (LLFPs), which are produced in nuclear reactors, is one of the candidate techniques for the reduction and/or reuse of LLFPs. To design optimum
pathways for the transmutation process, several nuclear
reactions have been studied by using LLFPs as secondary beams. The studies indicate that proton- and/or
deuteron-induced spallation reactions at intermediate
energies (100–200 MeV/nucleon) are suﬃciently eﬀective for the LLFP transmutation.1–3) We note that protons/deuterons lose their energies in materials; therefore, measurements at lower reaction energies are deﬁnitely desired for the application of transmutation. In
this study, the isotopic production cross sections ofproton- and deuteron-induced reactions on 107 Pd and93
Zr at 20–30 MeV/nucleon were measured under an inverse kinematics condition. The experiment was conducted at the OEDO4) beamline at RIBF. This was theﬁrst physics experiment using OEDO. Detailed descriptions of the setup and procedure can be found in Ref. 5).
Figure 1 shows the preliminary results for the isotopic production cross sections of the proton-induced
reactions on 107 Pd. Considering the energy loss of thebeam in the target, the measured cross sections are theones averaged over 25–30 MeV/nucleon. The sensitivity threshold of the measurement was 5 mb because ofstatistics. We determined the cross sections for ﬁve isotopes (107–105 Ag and 106, 105 Pd).
The results show signiﬁcant production of Ag isotopes;
about 70% of the total cross section is exhausted by Ag
isotopes. This can be understood by the compoundnuclear process: 107 Pd + p →108 Ag∗ . The Ag isotopes
are probably produced by the evaporation of neutrons
from the highly excited compound nucleus 108 Ag∗ . Actually, the trend is completely diﬀerent from the highenergy spallation reaction case,2) in which the contribution of Ag isotopes is less than 10%.
The curves in Fig. 1 show the excitation functions
∗1
∗2
∗3
∗4
∗5

∗6
∗7
∗8
∗9

Fig. 1. Isotopic production cross sections of the protoninduced reactions on 107 Pd.

evaluated by TENDL-2017.6) The cross sections of Ag
and Pd isotopes were reasonably reproduced by theevaluation. On the other hand, the cross sections of103, 102
Rh were considerably overestimated; TENDL predicted signiﬁcant values for 103, 102 Rh, but they were notdetected in the experiment.
The present data, as well as higher-energy data, would
provide an eﬀective guideline for a possible solution of
LLFP transmutation. The results will be ﬁnalized soon,and the preparation for publication is in progress. Regarding the 93 Zr data, the analysis for particle identiﬁcation is ongoing.
This work was funded by the ImPACT Program of theCouncil for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
References

Center for Nuclear Study, the University of Tokyo
RIKEN Nishina Center
Department of Physics, Kyushu University
Department of Advanced Energy Engineering Science, Kyushu
University
Department of Physics, the University of Tokyo
Research Center for Nuclear Physics, Osaka University
Department of Physics, Tokyo Institute of Technology
WNSC, IPNS, KEK
Department of Physics, Rikkyo University

1) H. Wang et al., Phys. Lett. B 754, 104 (2016).
2) H. Wang et al., Prog. Theor. Exp. Phys. 2017, 021D01(2017).
3) S. Kawase et al., Prog. Theor. Exp. Phys. 2017, 093D03(2017).
4) S. Michimasa et al., Prog. Theor. Exp. Phys., accepted.
5) M. Dozono et al., RIKEN Accel. Prog. Rep. 51, 99 (2018).
6) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).
-8-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Transverse momentum dependent fragmentation measurements in
Belle†
R. Seidl∗1†∗1d2σ/dz dP hT [fb/GeV/c]ready existing transverse spin data from RHIC andsemi-inclusive scattering and inform on the data to betaken at the EIC.

810

0.10 < z < 0.15

107

0.20 < z < 0.25

0.25 < z < 0.30

0.30 < z < 0.35

0.35 < z < 0.40

0.40 < z < 0.45

0.45 < z < 0.50

0.50 < z < 0.55

0.55 < z < 0.60

0.60 < z < 0.65

0.65 < z < 0.70

0.70 < z < 0.75

0.75 < z < 0.80

0.80 < z < 0.85

5

10

104
3

10

0.85 < T < 0.90102d2σ/dz dP hT [fb/GeV/c]

0.15 < z < 0.20

6

10

107
6

10

5

10

4

10

3

10

d2σ/dz dP hT [fb/GeV/c]

102
10
107
6

10

5

10

104
3

10

102

d2σ/dz dP hT [fb/GeV/c]

10
0

6

10

5

10

3

10

10
1
0.5

1

1.5

2
2.5 0
PhT [GeV/c]

0.5

1

1.5

2
2.5 0
PhT [GeV/c]

0.5

1

1.5

1

1.5

p/p

102

0

0.5

π±

104

2
2.5
PhT [GeV/c]2
2.5
PhT [GeV/c]

K±

Fig. 1. Diﬀerential cross sections for pions (black circles),kaons (blue squares) and protons (green triangles) as
a function of PhT for the indicated z bins and thrust0.85 < T < 0.9. The error boxes represent the systematic uncertainties. Due to the large uncertainties inthem, z bins above 0.85 are not displayed.
σ2P [GeV2/c2]
hT

The Belle experiment at the asymmetric e+ e− collider KEKB provides a very large data set for not only
the study of ﬂavor physics but also the study of thestrong interaction, QCD. The clean initial state allows
very eﬀective measurements of fragmentation functions. Fragmentation functions describe the formationof conﬁned, ﬁnal state hadrons out of asymptoticallyfree high-energetic partons. These fragmentation functions (FF) therefore tell us about the conﬁnement process in itself. They also can be seen as tools used in order to extract ﬂavor and/or spin information in parton
distribution functions via their diﬀerent sensitivities.
The transverse momentum dependence of distribution
and fragmentation functions is of particular imiportance as it is closely related to the three-dimensional
structure of the nucleon planned to be measured ingreat detail at the Electron-Ion-Collider, EIC, and theCollins and Sivers eﬀects. In Belle, one has the uniquechance to study the transverse momentum dependencein single hadron fragmentation using the event-shapevariable thrust as the reference axis and as proxy forthe initial quark-anti-quark axis. For this analysisa,−1data sample√ of 655 fb collected at the center-or-massenergy of s = 10.58 GeV was used. Single charged
pions, kaons and protons were√selected as a functionof fractional energy z = 2Eh / s, the thrust value T
and the transverse momentum. The raw distributions
were corrected for particle mis-identiﬁcation, momentum smearing, backgrounds from other processes, recontruction and acceptance as well as initial-tate radiation, similar to the description of previous results.1,2)
The resulting transverse momentum dependent crosssections are shown in Fig. 1 for 0.85 < T < 0.9. The
behavior is overall very similar between particle species
with protons having generally narrower distributions.
As expected by theory, the low transverse momentum
region PhT < 1 GeV can be successfully described by
Gaussians. However, unlike theory predictions of arather simple fractional energy dependence, the widthsof these Gaussian ﬁts are increasing at small fractionalenergies while they decrease again at higher fractionalenergies. In these ﬁts, pions and kaons show similar
widths while those of proton are signiﬁcantly smaller,
as can be seen in Fig. 2. When compared for diﬀerent thrust values, the widths are largest at low thrust,
where the events are more spherical while they become
smaller as the events become more collimated.
These results will be used in global fragmentation
analyses in order to increase the precision of the al-

K±

π±

0.6

p/p

0.85 < T < 0.90

0.5
0.4
0.3
0.2
0.1
0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

z

1

Fig. 2. Gaussian widths as a function of z for pions (black
circles and boxes), kaons (blue squares and boxes) andprotons (green triangles and boxes) and thrust 0.85 <T < 0.9. The error boxes represent the corresponding
systematic uncertainties as described in the text.

References
1) R. Seidl et al. [Belle Collaboration], Phys. Rev. D 96,
032005 (2017).
2) R. Seidl et al. [Belle Collaboration], Phys. Rev. D 92,
092007 (2015).

Condensed from the article accepted in Phy. Rev. D
RIKEN Nishina Center-9-Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Measurement of elliptic flow of single electrons from semi-leptonic decay√of charm and bottom hadrons in Au + Au collisions at sN N = 200 GeV
Y. Ueda∗1,∗2 for the PHENIX Collaboration
Heavy ﬂavors (HFs), charm (c) and bottom (b) quarks,
are suitable probes for the study of quark gluon plasma(QGP). HFs are mainly produced from the hard scattering at the early stage of collisions because they havelarge masses (Mc ≈ 1.3 GeV/c2 , Mb ≈ 4.2 GeV/c2 ). HFs
reﬂect the space-time evolution of the QGP well. The
perturbative QCD calculations can be applied to the cand b quarks at the initial hard scattering in the collisions. It means that the yield of the c and b quarks
is calculated precisely. Also, the b quark mass is about
three times as heavy as the c quark mass. The measurement with c and b quark separation shows the quark
mass dependence of their quantities and behaviors in the
QGP. Therefore, the c and b quark measurement is essential for QGP research. The modiﬁcation of c and b
quarks provides information about QGP.
A Silicon Vertex Tracker (VTX) consisting of 4 layersof silicon detectors was installed at the RHIC-PHENIX
experiment in 2011 to reconstruct charged particle trajectories and their Distances of Closest Approach (DCA)
to the primary collision vertex. The DCA is related tothe decay length of the particles. As the decay lengthsof c and b hadrons are diﬀerent enough (D 0 ∼ 123µm, B 0 ∼ 455 µm), we can statistically separate electrons from the semileptonic decays of c and b hadrons
using the DCA, even with a lower integrated luminosity.
In 2014, the PHENIX collected about 15 billion minimum√
bias events from Au + Au collisions at sN N = 200 GeV,
which is 10 times larger than the previous dataset obtained in 2011. Additionally, the systematic uncertainties are reduced because the photonic background estimation and the VTX are improved.
For the HF study, we measure the centrality dependence of the nuclear modiﬁcation factors1) and the azimuthal anisotropy (v2 ) of the c and b electrons. v2 isoriginated from the initial geometry of the QGP. It thenFig. 2. Compared of charged hadron v2 with (a) charm and(b) bottom electron v2 .

expands the pressure gradient with the QGP evolution.
v2 reﬂects the hydrodynamic property of the QGP, e.g.,η/s, well. Therefore, the c and b electron separation measurement of v2 is essential for the study of the ﬂow eﬀect.
We installed the high-resolution detector FVTX at the
RHIC-PHENIX experiment in 2012 for the c and b electron v2 separation measurement. The FVTX detector
precisely measures the reaction plane, which is the reference of the v2 measurement. We measure the c and belectron v2 with smaller uncertainties using this detector.
A comparison of HF electron v2 using the 2014 dataset(black point) and the 2004 dataset (red point) is shownin Fig. 1. The new result is consistent with the previous result. On the other hand, the uncertainties became smaller because of the higher statistics in the 2014
dataset and the higher resolution provided by the FVTX
detector.
The HF v2 is statistically separated into c → e v2 andb → e v2 using the DCA information. The DCA region isseparated into 2 DCA regions: c and b rich regions. The
c/b
c/b electron v2 (v2 ) is described with the calculated b
fraction fb (c/b) and background (BG) fraction fBG (c/b)
for the c/b rich region using the following formulas.
v2meas (c) = fb (c) · v2b + (1 − fb (c)) · v2c + fBG (c) · v2BG (c)v2meas (b) = fb (b) · v2b + (1 − fb (b)) · v2c + fBG (b) · v2BG (b)Fig. 1. Comparison of HF v2 using 2007 dataset and 2014
dataset.

Here, v2meas (c/b) and v2BG (c/b) are the measured inclusiveelectron v2 and BG v2 for the c/b rich region, respectively. The c and b electron v2 are separately calculated
by solving these equations.
A comparison of (a) c electron v2 (red point) and (b)b electron v2 (blue point) with the charged hadron v2(pink point) is shown in Fig. 2. It is the ﬁrst measurement of b electron v2 at RHIC. The c and b electronv2 are smaller than the charged hadron v2 . Also, thec electron v2 seems to be larger than the b electron v2 .
Unfortunately, the large uncertainty makes b electron v2
consistent with zero. We will improve the method for thec and b electron v2 separation measurement.
Reference∗1∗2

RIKEN Nishina Center
Department of Physics, Hiroshima University

1) K. Nagashima for the PHENIX Collaboration., Nucl.
Phys. A 967, pp. 644–647 (2017).
- 10 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

The chiral propulsion eﬀect†
Y. Hirono,∗3 D. E. Kharzeev,∗1,∗2,∗3 and A. V. Sadofyev∗4∫ 3e2magnetic helicity given by H = 4π
d x A · B, where2
A is the vector potential and B is the magnetic ﬁeld.
It is worth mentioning that taking the derivative of
this action with respect to the vector potential, one
readily ﬁnds the CME current: JCME = δSχ /δA ∝B. Supplementing the non-relativistic Abelian Higgs
model with the term given by Eq. (3), one can ﬁnd theequation of motion for a quantized magnetic vortex at
ﬁnite µ, as derived by Kozhevnikov:
[
]
3
(4)
Ẋ = CX ′ × X ′′ + µ X ′′′ + (X ′′ )2 X ′ ,2

The physics of chiral media has attracted a significant attention recently. Remarkably, it appears thatthe quantum chiral anomaly signiﬁcantly aﬀects themacroscopic behavior of chiral media and induces newtransport phenomena,1,2) such as the Chiral Magnetic
and Chiral Vortical Eﬀects (CME and CVE, respectively). CME and CVE refer to the generation of electric currents along an external magnetic ﬁeld or vorticity in the presence of a chirality imbalance. The resulting currents are non-dissipative due to the protection
by the global topology of the gauge ﬁeld. These chiraleﬀects are expected to occur in a variety of systems:
the quark-gluon plasma, Dirac and Weyl semimetals,
primordial electroweak plasma, and cold atoms. In
quark-gluon plasma, the chirality imbalance can beproduced by topological ﬂuctuations of QCD, or by
the combination of electric and magnetic ﬁelds that
accompany heavy-ion collisions.
Consider the motion of a vortex ﬁlament in a ﬂuid.
It can be described by the localized induction equation(LIE),(1)Ẋ = CX ′ × X ′′ ,where a tangential term 32 µ(X ′′ )2 X ′ is added to keep
the arc-length-preserving property.
In this paper we are interested in the behavior ofchiral solutions. We can ﬁnd a simple explicit solutionof the FME (4) having the form of a helix,κ cos[A(s − vp t)]
1  0
Xhelix (t, s) = 2 κ0 sin[A(s − vp t)]  ,(5)Aτ0 A(s − vg t)
where the constants κ0 and τ√
0 give the curvature andthe torsion of the helix, A = κ20 + τ02 , and the phase

where X = X(t, s) denotes the position of a vortex,
t is the time, s is the arc-length parameter, the dot
and the prime indicate the derivatives with respect tot and s respectively, and C is a parameter dependent
on the properties of the ﬂuid. Interestingly, the LIE (1)can be mapped to the non-linear Schrödinger equation(NLSE) by the so-called Hasimoto transformation,
[ ∫ s
]
′
′
ψ(t, s) = κ(t, s) exp i(2)τ (t, s )ds ,κ2and group velocities are given by vp = τ0 + µ(τ02 − 20 ),κ2

where κ(t, s) is the curvature and τ (t, s) is the torsion
of a vortex. NLSE is known to be a completely integrable system which has solitonic solutions and an inﬁnite sequence of commuting conserved charges. The
LIE possesses solutions that represent helical excitations propagating along the vortex; they are known as
Hasimoto solitons.
Let us now consider a system in which parity is broken by the presence of magnetic helicity; the corresponding term in the action is∫Sχ = dt µ H,
(3)

0

2
2
2
2
where
( 2 η ≡2τ)0 s+(ϵ −τ0 )t+µτ0 (3ϵ −τ0 ), ξ ≡ s−(2τ0 +µ 3τ0 − ϵ )t, and ϵ and τ0 are constants. This soliton
has a constant torsion given by τ0 and propagates inthe z direction. Its speed is modiﬁed by µ and reduces
to the original Hasimoto soliton at µ = 0.
To summarize, we have found that in chirally imbalanced media there exist helical excitations that carryenergy along the vortex (the Chiral Propulsion Eﬀect).

where µ is the “chiral” chemical potential, H is the

†

∗1
∗2
∗3
∗4

3κ2

vg = − τ00 − 2 0 µ. Note that the sign of τ0 determines
the handedness of the helix. The radius R and thepitch ℓ of the helix are given by R = κ0 /(κ20 + τ02 ), ℓ =2πτ0 /(κ20 + τ02 ).
Using the map between the FME and the Hirota
equation, we ﬁnd a propagating solitonic solution of
the FME,sech[ϵξ] cos [η]− ϵ2 2ϵ+τ02
2ϵXsol (t, s) =  − ϵ2 +τ02 sech[ϵξ] sin [η]  .
(6)2ϵs − ϵ2 +τ 2 tanh[ϵξ]References

Condensed from the article in Phys. Rev. Lett. 121, 142301(2018)RIKEN Nishina Center
Department of Physics and Astronomy, Stony Brook University
Department of Physics, Brookhaven National Laboratory
Los Alamos National Laboratory

1) K. Fukushima, D. E. Kharzeev, H. J. Warringa, Phys.
Rev. D 78, 074033 (2008) [arXiv:0808.3382 [hep-ph]].
2) D. E. Kharzeev, Prog. Part. Nucl. Phys. 75, 133 (2014)[arXiv:1312.3348 [hep-ph]].

- 11 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Superconducting RILAC booster†N. Sakamoto,∗1 M. Dantsuka,∗1 H. Hara,∗3 H. Imao,∗1 E. Kako,∗2 O. Kamigaito,∗1 K. Kusaka,∗1 K. Miyamoto,∗3
H. Nakai,∗2 H. Okuno,∗1 K. Ozeki,∗1 H. Sakai,∗2 K. Sennyu,∗3 K. Suda,∗1 K. Umemori,∗2 T. Watanabe,∗1
Y. Watanabe,∗1 K. Yamada,∗1 and T. Yanagisawa∗3
The RIKEN Heavy-Ion Linac (RILAC) is undergoing an upgrade to enable it to further investigate superheavy elements and produce of radioactive isotopes for
medical applications. In this project, a new superconducting (SC) electron cyclotron resonance ion source andSC booster linac (SRILAC) are being developed andconstructed. The SRILAC consists of 10 TEM quarterwavelength resonators that are operated at 73 MHz andcontained in three cryomodules (CMs). The goals of
the upgrade are listed in Table 1. It should be notedthat the fundamental frequency of the reference radio
frequency (RF) signal has been chosen as 36.5 MHz because it is the frequency for the RF system of the RIBF
accelerators.
As shown in Fig. 1, the SRILAC consists of three
CMs–CM1, CM2, and CM3–with a room-temperature
medium-energy beam transport (MEBT) between them.
The CMs do not contain superconducting magnets. The
design of the CMs is a modiﬁcation of a prototype CM
developed at RIKEN.1–3)
The operational parameters of the CMs are listed inTable 2. The gap length of the cavity is optimized for
β = 0.08 particles with a transit time factor (TTF) of
0.9. The gap voltage is 1.2 MV, which corresponds toan acceleration gradient Eacc of 6.8 MV/m with a synchronous phase of −25◦ . After the fabrication of theten SC-cavities, all cavities were tested and passed theacceptance test.5)
The SC-cavities are cooled by 4-K liquid helium provided by a liquid helium cryogenic system using a HELIAL MF refrigerator (Air Liquide).
RILAC

SRILACMEBT Top View

Liquid Helium Transfer Line

A1

CM1

A2

CM2

CM3

Beam
Differential Pumping System

Beam
Floor

CM1

A2

CM2

∗1
∗2
∗3

Before12 DTLs
37.75/75.5
25 (A/q = 5)After
8 DTLs, 3 CMs
36.5/73.0
39 (A/q = 6)

Table 2. Operational parameters of the SRILAC.
Frequency (MHz)Einj (MeV/nucleon)
Eext (MeV/nucleon)
Number of cavities
Cavity typeMax. gap voltage (MV)
Synchronous phase (◦ )Max. acc. gradient (MV/m)
Target Q0 (at Eacc = 6.8 MV/m)
Beam current (µA)
Qext
Amplifier output (kW)73.0 (c. w.)
3.6
6.5 for A/q = 6
10
TEM, λ/4
1.2
−25
6.8
1 ×109≤100
1–4.5 ×106
7.5

For the MEBT, a newly designed beam energy position monitor will be employed instead of the traditional wire scanners. Because beam measurement is
non-destructive, ideally there is neither outgassing nor
spattering to produce particulates in the high-vacuum
sections.
Because the SRILAC will be installed in the existing
facility, it is important to have an isolation system indicated as a diﬀerential pumping system in Fig. 1 toprevent contamination of the SC-cavities, which deteriorates the performance of the SC-cavities.
Full assembly of the CM will be ﬁnished in the ﬁrst
quarter of 2019 and its installation in the accelerator
building is scheduled for March 2019. After installing
the MEBT, including the diﬀerential pumping systems,
cooling and RF testing will be performed during thesecond quarter of 2019 with the aim of full beam commissioning in the third quarter of 2019.
References

CM3

Fig. 1. Layout of the Superconducting RILAC (SRILAC).
†

UpgradeNumber of tanks
Frequency (MHz)Total Vacc (MV)Side View

1300 mmA1

7540 mmTable 1. Specifications of RILAC before and after upgrade.

Condensed from the proceedings of LINAC2018, Beijing,
September 2018, WE2A03, p. 620.
RIKEN Nishina Center
KEK, Tsukuba
MHI-MS, Kobe

- 12 -

1) K. Ozeki et al., Cryomodule and power coupler for
RIKEN Superconducting QWR, LINAC2016, East Lansing, September 2016, TUPLR061, p. 598.
2) K. Yamada et al., First Vertical Test of Superconducting
QWR Prototype at RIKEN, LINAC2016, East Lansing,
September 2016, THPLR040, p. 939.
3) N. Sakamoto et al., SRF2017, WEYA01; K. Yamada etal., PASJ 14th Annual Meeting, TUOL02.
4) http://www.jst.go.jp/impact/en/program/08.html
5) K. Yamada et al., Performance test of bulk-niobium cavities for new superconducting linear accelerator, in thesereports.

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Remodeling of acceleration cavity resonators for RIKEN Ring Cyclotron
K. Yamada,∗1 K. Suda,∗1 N. Sakamoto,∗1 and O. Kamigaito∗1
The RIKEN Ring Cyclotron (RRC)1) has two acceleration cavities that consist of variable-frequency halfwavelength resonators constructed over 30 years ago.
The design range of resonant frequency is between 20
and 45 MHz. Additionally, the resonant frequency canbe varied by moving two movable boxes,2) as shown in
Fig. 1. During the acceleration of 238 U, which is oneof the most important beams in the operation of RIBF,
the maximum beam current in the RRC was limited bylarge beam losses in the electrostatic deﬂection channel(EDC) that were caused by small turn separations and aspace-charge eﬀect owing to the insuﬃcient acceleration
voltage of the cavity resonators. The 238 U beam wasaccelerated in a ﬁxed-frequency mode using RILAC23,4)
as an injector. Consequently, the RRC resonators haveto be operated at a low frequency of 18.25 MHz, whichis less than the designed lower limit. To resonate at thislow frequency, the capacitance was increased by bringing the movable box close to the location of 20 mm fromthe dee electrode, which caused the extremely low shuntimpedance and frequent discharge. Moreover, the acceleration voltage could not be raised above 80 kV/gap.
Therefore, we decided to increase the acceleration voltage at 18.25 MHz operation by remodeling the innercomponent of the stems and dee electrode, excluding
the outer box of the resonator and the movable boxes,
respectively.
The frequency range of the RRC resonator was shiftedto the lower side by inserting notches in the stem thatwas originally straight. Because the RRC resonator had
not operate at a frequency higher than 39 MHz in recent
years, the frequency range after remodeling was set to
be 16–38 MHz. Although this slant type stem is similar
to the early design5) of the RRC resonator, the shuntimpedance, voltage distribution, and frequency range
were optimized by changing the notch sizes based on
3D electromagnetic calculation using Microwave Studio(MWS).6) Figure 1 shows a calculation model of MWS
for the original resonator and the modiﬁed resonator. It
was expected that the shunt-impedance could be doubled at 18.25 MHz by this remodeling.
The remodeling work on site was carried out fromFebruary to March 2018. We performed a low power
RF test with a network analyzer in April. According to
the test results, it was found that the frequency range
and quality factor Q0 were almost consistent with the
expected values for each resonator. Figure 2 shows animage of the inside of the resonator after modiﬁcation.
Simultaneously, the old-degraded power supplies for thegrid of tetrodes in RF power ampliﬁers were updated forstable operation.
The new resonators were used for the machine time
∗1

RIKEN Nishina Center- 13 -

Fig. 1. Calculation models of the original cavity (left panel)and remodeling cavity (right side) used in the MWS.

Fig. 2. Inside view of the remodeled RRC cavity.

from May and showed good performance in the operation from 18.25 MHz to 32.6 MHz. Especially, a stable
operation with the voltage of 120 kV/gap was realizedfor 18.25 MHz owing to the shunt-impedance improvement and discharge decrement. However, owing to thewater leakage from the cooling channel in the vacuum
due to the production problem, we are currently considering countermeasures.
References

1) Y. Yano, Proc. 13th Int. Cyclo. Conf., 102 (1992).
2) T. Fujisawa et al., Nucl. Instrum. Methods Phys. Res. A
292, 1 (1990).
3) K. Yamada et al., Proc. of IPAC12, TUOBA02, 1071
(2012).
4) K. Suda et al., Nucl. Instrum. Methods Phys. Res. A 722,
55 (2013).
5) K. Ogiwara et al., RIKEN Accel. Prog. Rep. 18, 172(1984).
6) https://www.cst.com/products/cstmws .

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

He gas stripper with N2 gas-jet curtain
H. Imao,∗1 H. Okuno,∗1 H. Hasebe,∗1 N. Ikoma,∗1,∗2 and O. Kamigaito∗1
The present intensity of uranium beams injected into
the ﬁrst stripper is reaching ∼1013 /s at the RIBF. Thishas given rise to various types of diﬃculties in the operation of He gas stripper. A small fraction of beam loss
in the He gas stripper1,2) causes serious hardware troubles or radioactivities. The qualities of beams injectedto the He stripper become worse at high-intensity operations owing to the space charge eﬀect in the RIKEN
ring cyclotron (RRC) placed 7 m upstream of the He
stripper. The diameter of the oriﬁces in the He stripper
must be enlarged for the eﬃcient transmission of highintensity beams. In contrast, a small leak of He gas to
the RRC becomes a serious problem at high-intensity
operations. The RRC has only 14 cryopumps with total
pumping speed of 120 m3 /s for N2 . Owing to the small
pumping capacity of He gas, the leaked He gas is accumulated in the RRC gradually. Collisions between U
ions and He atoms in the RRC can easily change theircharges and cause beam loss. For the acceleration ofhigh-intensity uranium beams, such beam loss induces
further losses by the local pressure rise due to the gas
desorption (dynamic vacuum).
To solve these inevitable problems, we invented the N2
gas-jet curtain method. By using curtain-like nitrogengas-jet that separates two rooms (Fig. 1), we can block
the helium ﬂow to the low-pressure side and the leaked
gas is exchanged to N2 from He.
Based on the concept, we designed and developed theFig. 1. Concept of N2 -jet curtain. The jet separates tworooms.

Fig. 2. Performance of N2 -jet curtain.
∗1∗2

Fig. 3. Enlargement of diameters of tapered tube oriﬁces.

Fig. 4. Comparison of eﬀective charge stripping eﬃciencies.

actual device to make the N2 gas-jet curtain optimized
with CFD calculations. The device was installed in the
He stripper and tested. Figure 2 shows the demonstrated performance of the N2 gas-jet curtain method.
It is evident that the sealing abilities signiﬁcantly increased. The gas that leaked downstream was successfully exchanged to nitrogen, as we desired. In addition,
the N2 gas-jet curtain worked as a pre-stripper. Initialstripping in N2 -jet curtain (∼30 µg/cm2 ) reduced therequired pressure of He gas up to ∼15%.
By utilizing the gas-jet curtain, we enhanced the oriﬁce diameters as shown in Fig. 3. The 4D acceptanceof the system is 1.5 times higher than that of previous
systems.
The improved system was applied in the user runs in2017 and 2018. The output intensities were increased
with more than 25% owing to the increasing transmission eﬃciencies (Fig. 4). No serious pressure rise in
the RRC was observed. The N2 gas-jet curtain method
was greatly contributed to the enhanced output intensity (71 pnA at 345 MeV/nucleon) achieved in 2017.
References

RIKEN Nishina Center
Department of Energy and Environment Science, Nagaoka
University of Technology- 14 -

1) H. Imao et al., Phys. Rev. ST Accel. Beams 15, 123501 (2012).
2) H. Imao et al., in Proc. IPAC’13, Shanghai, paper
THPPA01 & THPWO038 (2013).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Upgrade of particle selection system for Rare RI Ring experiments
Y. Abe,∗1 Y. Yamaguchi,∗1 M. Wakasugi,∗1 D. Nagae,∗1 F. Suzaki,∗1 and for the Rare RI Ring collaboration
We developed a particle selection system for Rare RI
Ring experiments. This system selects particles to be injected into R3 using the flight time and energy loss (∆E)
information obtained at F3 in the BigRIPS focal plane.
In the early stage of development,1) the signals from detectors were processed using the standard NIM modules
with a processing time of at least 60 ns. Because it is necessary to transmit the trigger signal to the kicker magnets as soon as possible, we developed dedicated modules
with the particle-selection function. A conceptual circuit diagram is shown in Fig. 1. Because these modules
are placed at F3, they are remote-controlled through theethernet communication. The signal processor consistsof two types of modules. One is for particle selection(module A). This processes the raw signals related to
the flight time and energy loss information.
Each particle arrives at a certain time relative to the
RF Phase. The module A applies coincidence or vetologic with time window created by the RF signal andcontrols the output signal rate by adjusting the deadtime of the module. Therefore, the particle is temporally separated and the output rate is appropriately adjusted. The module A has a window-type discrimination
function and can select a certain pulse height signal depending on the energy loss. In combination with both
functions, in principle, it is possible to select a single
isotope. The required processing time is approximately
15 ns. The other module (module B) combines OR-logic
with the signals from two or more types of module A.
Because module A can control the rate of output signal
in the given time window, it is possible to control theabundance of isotopes to be injected into R3. The processing time required in module B is also approximately
15 ns. Furthermore, module B can limit the total rate of
the output signal and adjust the delay of the signal usedas the excitation trigger for the kicker magnets.
We practically used the modules in the R3 experiments in fall 2018.2,3) The target nuclei chosen in theexperiments were the neutron-rich Ni and Pd isotopes.
In these experiments, a 2 mm-thick plastic scintillation
detector was installed additionally at F3 to get ∆E information for particle selection. Figure 2 (a) shows a typicalparticle-identification (PID) plot and 77 Ga has the highLinear
FIFO

Threshold / Rate

Module A1< 80 Hz (typical)

Coin. / Veto

L

Rate/Delay

Delay

F3 Plastic

RF(Accelerator)

Discriminator

Module B< 100 Hz

Trigger(Kicker / DAQ)

Delay

R

Coin. / Veto

Linear
FIFO

Module A2
Threshold / Rate

< 20 Hz (typical)

Fig. 1. Conceptual circuit diagram for particle selection andabundance tuning. Frequency of the output signal is adjustable.
∗1

est abundance. The abundance of other isotopes could
be increased by selectively getting rid of the Ga events,
as shown in Fig. 2 (b), where 76 Zn is the measure component. We increased the purity of nuclei in the moreneutron-rich side by shifting the time window and adjusting the output rate. Their purities can be higher
than that of 77 Ga, as shown in Fig. 2 (c). Owing tothis system, we successeded in the mass measurement of
neutron-rich nuclei. This system is useful not only for R3
experiments but also other experiments on exotic nuclei.

RIKEN Nishina Center

Fig. 2. (a) Typical PID plot of the secondary particles with
TOF and ∆E. (b) Ga isotope was ridded by the selection system. (c) Typical example of abundance control.
Broken-lines show the time window and frequency of theoutput rate set by each module A.

References

1) Y. Abe et al., RIKEN Accel. Prog. Rep. 50, 186 (2017).
2) A. Ozawa et al., in this report.
3) S. Naimi et al., in this report.

- 15 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Aberration correction study for high-resolution optics of BigRIPS using
sextupole magnets
T. Nishi,∗1 D. S. Ahn,∗1 N. Fukuda,∗1 N. Fukunishi,∗1 H. Geissel,∗1,∗2 N. Inabe,∗1 K. Itahashi,∗1 K. Kusaka,∗1
S. Y. Matsumoto,∗1,∗3 Y. Shimizu,∗1 T. Sumikama,∗1 H. Suzuki,∗1 M. Takaki,∗4 H. Takeda,∗1 Y. K. Tanaka,∗1,∗2
T. Uesaka,∗1 Y. Yanagisawa,∗1 and K. Yoshida∗1
We performed a test experiment in May 2018 to develop new optics of BigRIPS with higher order aberrations diminished by sextupole magnets. The optics is designed for spectroscopy of deeply bound pionic atoms1)
and search for double Gamow-Teller giant resonance.2)
Until now, we have achieved double the resolving powerwith the new optics compared to a standard design; however higher order aberrations remain. For example, thecorrelation between the horizontal position and the angle at F5 strongly depends on momentum, which is referred to as (x|aδ). In other words, the focal plane at
F5 is inclined at 87◦ (almost parallel to the beam axis).
This causes position-dependent deterioration of the resolution coupled with multiple scattering. To improve thiscondition, we developed a new optics using sextupoles.
Taking advantage of the mirror-symmetrical conﬁguration of the magnets in BigRIPS, we designed a new
optical setting as shown in Fig. 1. Trajectories in several
corresponding sections, namely between F0-F1 and F1F2, and between F3-F5 and F5-F7, are designed to besymmetric at the ﬁrst order. The ﬁeld strengths of the
sextupoles are also constrained to have (anti) symmetry in the same sections based on the sextupole coupling
coeﬃcients.3) Through these constraints, many aberrations will be canceled out, and others are expected tohave simple responses to the ﬁeld strengths of the sextupoles.
In the test experiment, we systematically varied theﬁeld strengths of the sextupoles and measured the aberrations. We utilized fragments of 9 C produced by a primary 18 O beam of 230 MeV/nucleon and a 30 mm thick
Be target. The 9 C distributions in terms of angle andmomentum are large enough to have a nearly ﬂat distribution in the acceptance of BigRIPS. We detected 9 C
by PPACs at F3, F5, and F7 and a plastic scintillator
at F7. Aberration coeﬃcients such as (x|a2 ) or (x|aδ)
were evaluated at F3 and F5. During the measurement,
we applied very narrow momentum gates of 0.1%, whichwere set by time of ﬂights between F0 and F7 using the
RF and F7 scintillator signals.
As a result, we found clear dependence of aberrationcoeﬃcients on the sextupole settings as expected; further, we optimized the settings to suppress the aberrations. Figure 2 shows correlation between position andangle in the horizontal direction at F5, where our main
detectors will be installed, with the sextupoles all oﬀ
∗1
∗2
∗3
∗4

Fig. 1. Calculated horizontal trajectories based on thirdorder matrix elements by simulation code. Blue, green,and yerrow correspond to +1.0%, 0.0% and −1.0% of deviations, respectively. The sextupole magnets are also
taken into account in the calculation.

Fig. 2. Position and angle correlation at F5 focal plane. Blue,sky blue, black, pink, and red correspond to the deviations of +1.0%, +0.5%, 0.0%, −0.5%, and −1.0%, respectively. (Left) All of the sextupole magnets are oﬀ.
(Right) All of the sextupole magnets are optimized.

(left) and all on after optimization (right). The diﬀerent colors represent diﬀerent momenta. The left panel
indicates a clear third order angular dependence, which
also depends on the momentum. In the right panel, allangular dependencies almost disappear.
In conclusion, we successfully controlled the aberrations using the sextupoles by maintaining strict conditions of symmetry. After optimization, dominant aberrations were clearly corrected. This study is a part ofour work to develop a dispersion-matched optical system
of SRC - BigRIPS. We performed another test experiment to study the optical properties between SRC and
F0 in June 2018 as found in Ref. 4).
References

1) K. Itahashi et al., RIBF Proposal 135, (2015).
2) T. Uesaka et al., RIBF Proposal 141, (2015).
3) K. L. Brown, SLAC Report No. 91, (1970).
4) S. Y. Matsumoto et al., in this report.

RIKEN Nishina Center
GSI Helmholtzzentrum für Schwerionenforschung GmbH
Department of physics, Kyoto University
CNS, University of Tokyo- 16 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)In-gas-jet laser ionization spectroscopy at KISS
Y. Hirayama,∗1 Y. X. Watanabe,∗1 P. Schury,∗1 M. Mukai,∗2 H. Choi,∗3 M. Ahmed,∗1,∗2 Y. Kakiguchi,∗1
M. Oyaizu,∗1 M. Wada,∗1 and H. Miyatake∗1
600

∗1

∗2
∗3

Counts (arb. u.)

We developed the KEK Isotope Separation System(KISS)1) to study the nuclear properties of neutronrich isotopes with neutron numbers around N = 126.
To study the nuclear structures at KISS, we measured
the hyperﬁne structure (HFS) of 199 Pt and 196, 197, 198 Ir
to determine the magnetic dipole moment and thechange in charge radius using the in-gas-cell laser ionization spectroscopy technique.2)
The present resolution of Γ = 12 GHz (FWHM) in
the HFS spectra measured by the in-gas-cell laser ionization technique was governed by pressure broadening(typically Γp = 10 GHz in FWHM), Doppler broadening (ΓD = 1.1 GHz), and laser bandwidth (ΓL =3.4 GHz). To improve the resolution, the in-gas-jet(collinear) laser ionization technique was successfully
established by the KU Leuven group3) to obtain precise
laser spectroscopy. In the case of in-gas-jet laser ionization technique, Γp and ΓD were drastically reduced
to 0.05 and 0.3 GHz owing to the spectroscopy in lowpressure and low-temperature gas jet, respectively. ΓL
can be improved to be 0.1 GHz by applying a narrowband laser system. Finally, the evaluated resolution
will be Γ = 0.35 GHz in FWHM.
To determine the electromagnetic moments and isotope shifts with higher precision, we have been developing an in-gas-jet laser ionization spectroscopy technique at KISS. We developed and installed a Laval
nozzle to obtain a gas jet with uniform velocity distribution,3) S-shaped pseudo-radio frequency quadrupole(S-RFQ) for the production and transportation oflaser-induced singly charged ions by collinear laser
spectroscopy, and a new narrow-band laser system.
The designed Mach number of the Laval nozzle is6.3, and the expected diameter and velocity of thegas jet are approximately 4 mm and 538 m/s, respectively. The laser system consists of a pumping laserof Nd:YAG (EdgeWave, 355 nm, 60 W), narrow-band
seed laser (TOPTICA, DLC DL Pro HP), and dyeampliﬁer (Sirah).
Figure 1 shows the HFS spectra of 198 Pt (I π = 0+ )and 194 Pt (I π = 0+ ) measured using the in-gas-celland in-gas-jet laser ionization techniques, respectively.
No HFS was observed due to I π = 0+ of both isotopes.
Therefore, the widths measured by both techniques are
the intrinsic resolutions of the techniques. The widths
obtained using the in-gas-cell and in-gas-jet laser ionization techniques were 12.5(5) and 0.6(1) GHz in

194

+

198

Pt (I = 0 )

500

π

+

Pt (I = 0 )
π

400
300
200
100
0

−10

−5

0

5

Laser frequency [GHz]10

Fig. 1. HFS spectra of 198 Pt (I π = 0+ ) and 194 Pt (I π =0+ ) measured using the in-gas-cell and in-gas-jet laser
ionization techniques, respectively, under the gas cellpressure of 80 kPa (background gas-pressure 50 Pa).
For the in-gas-cell laser ionization spectroscopy, the ionization scheme in Ref. 2) was used. We used the combination of λ1 = 225.000 nm and λ2 = 355 nm for the
in-gas-jet laser ionization spectroscopy. Horizontal axis
shows the deviation from each λ1 of the applied ionization schemes. Horizontal uncertainties stemmed fromwavemeters were 0.6 and 0.06 GHz for the in-gas-celland jet spectroscopy, respectively.

FWHM, respectively. Thus, we signiﬁcantly improved
the resonance width by applying the in-gas-jet laser
ionization technique. The gas-jet velocity was deduced
to be 537(5) m/s from the Doppler shift of the HFS
spectra of 194 Pt measured by the in-gas-jet collinear.
The gas-jet velocity was signiﬁcantly consistent withthe designed value of 538 m/s. From the measurements, we conﬁrmed that the experimental equipmentused in this study was successful.
However present width of 0.6 GHz is broader thanour expected width of 0.35 GHz owing to the Doppler
broadening eﬀect. To achieve the expected width,
we will optimize the background gas-pressure to create a gas jet with uniform velocity distribution.3) Despite the present width of 0.6 GHz, we could measure the electromagnetic moments and isotope shift
more precisely. The feasibility study by simulating the199
Pt HFS spectra was performed and reported in thisprogress report by H. Choi.4)
References

1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 412, 11 (2017).
2) Y. Hirayama et al., Phys. Rev. C 96, 014307 (2017).
3) Y. Kudryavtsev et al., Nucl. Instrum. Methods Phys.
Res. B 297, 7 (2013).
4) H. Choi et al., in this progress report.

Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator
Research Organization (KEK)
Department of Physics, University of Tsukuba
Seoul National University- 17 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Microgram-order palladium isotope separation by odd-mass-selective
photoionization
T. Sonoda,∗1 T. Kobayashi,∗2 T. Fujiwara,∗2 Y. Nagata,∗2 H. Ishiyama,∗1 V. Sonnenschein,∗3 M. Oohashi,∗3
A. Takamine,∗1 M. Rosenbusch,∗1 I. Katayama,∗1 H. Tomita,∗3 T. M. Kojima,∗1 P. Schury,∗4 and K. Midorikawa∗2
High-level radioactive wastes generated from nuclear
power plants contain small percentages of platinumgroup metals such as palladium, rhodium, zirconium,
and plutonium, which are valuable resources for industrial applications. A novel research project has been
started by the Impulsing Paradigm Change through Disruptive Technologies Program (ImPACT, Project manager: R. Fujita), which includes (1) the separation of
those valuable metals from ﬁssion waste, (2) the separation of long-lived and short-lived nuclei, and (3) the nuclear mutation from long-lived to short-lived nuclei. Oneof the key techniques in (2) was successfully advanced in
the method using odd-mass-selective laser excitation.1)
The separation of even- and odd-mass-number isotopesof Pd using orthogonally polarized lasers was demonstrated with ionization that was 10,000 times more efﬁcient1) than the scheme used so far. From a practicalperspective, the yields on the separation of even- andodd-mass-number isotopes must be comparable to Avogadro’s number of atoms for a large amount of nuclear
waste.
We demonstrated stable Pd isotope separation on a
microgram order by photoionization using a high-power,
high repetition rate pulsed laser system.2) The experimental apparatus is shown in Fig. 1. The Pd vapor was
produced by an electron beam that irradiated Pd samples in a crucible. Two linearly polarized beams withparallel polarization were applied for the selectively resonant ionization of odd-mass Pd isotopes among stable
six isotopes (102, 104, 105, 106, 108, 110 Pd). We succeeded in
the dominant photoionization of the105 Pd.
Two Frequency doubled Nd:YAG InnOSlab lasers(EdgeWave) individually pumped two dye lasers having a pulse width of 10 ns and repetition rate of 10 kHz.
Thickness meter
Photoionization zone

Gold plate
Current meter

10-4PaNd:YAG

Dye laserBBO

Nd:YAG

Dye laserBBO

Nd:YAG

∗1
∗2
∗3
∗4

Ti:Sapphire -BBO

A
Power
supplyDichroic mirror

Deflector for
non-photoionized ions
Alternative

Pd

Heat shield
EB-Gunoriginal gold color

Gold color was changed due to photoionized Pd collection.

Fig. 2. The gold plate implanted by selectively ionized 105 Pd(total deposition time is 3 h 23 min).

Also, there is an intra-cavity SHG in a Ti:Sapphire laser
system pumped by Nd:YAG, whose repetition rate andpulse width are 10 kHz and 35 ns, respectively. The
ﬁrst excitation wavelength (λ1 ) of 244.9 nm was produced by the ﬁrst dye laser after frequency doublingin a BBO crystal, which excites Pd atoms into the
4d9 (2 D3/2 )5p[1/2] state. The typical power of λ1 was
100 mW. The second dye laser or Ti:Sa laser produces
the second excitation wavelength (λ2 ) of 361.023 nm via
frequency doubling in a BBO crystal placed at the external (dye) and internal (Ti:Sa) cavity conﬁguration. The
λ2 excites Pd atoms to the Rydberg autoionizing state
4d9 (2 D3/2 )9d[3/2]. We used dye or Ti:Sa, depending on
the situation. The typical power of λ2 in the case of
Ti:Sa was 2 W, while that in the case of dye was 1.5 W.
Photoionized 105 Pd ions were collected on the gold plateon which a collection voltage of −50 V was applied. The
distance between the gold plate and the ionization area
was about 5 cm. We conﬁrmed the yields of Pd ionsand identiﬁed the Pd element from the oﬀ/on resonant
frequency by monitoring with a current meter. The typical current level attributed to the photoionized Pd was
10 µA.
Figure 2 shows the gold plate after collecting photoionized 105 Pd ions for 3 h and 23 min. From the valueof the total deposition current, we deduce the total number of 105 Pd to be 3.0 × 1017 , which corresponds to aweight of 50 µg. For the ﬁrst time, we conﬁrmed Pd
isotope separation in microgram orders by using oddmass-selective laser excitation.
References

RIKEN Nishina Center
RIKEN Center for Advanced Photonics
Faculty of Engineering, Nagoya University
High Energy Accelerator Research Organization (KEK)1) C. Locke et al., Appl. Phys. B 123, 240 (2017).
2) T. Sonoda et al., Nucl. Instrum. Methods Phys. Res. A
877, 118 (2018).

- 18 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Introducing silver atoms into superfluid helium for precision laser
spectroscopy

∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Department of Advanced Sciences, Hosei University
Department of Physics, Okayama University RIIS
Department of Physics, Osaka University
Department of Physics, Toho University- 19 -

3500

LIF

Magnetic Field

3000

12
9

2500

6

2000

3

1500
1000

15

0
0

200

400

600

800

Magnetic Field [G]In the Optical Radioisotope atom Observation inCondensed Helium as Ion-catcher (OROCHI), theshort-lived and low-yield radioisotope (RI) atoms generated as high-energetic ion beams at accelerator facilities are stopped in a very narrow region in superﬂuid
helium (He II) owing to the high density of He II. LaserRF and laser-microwave (MW) double resonance spectroscopy for the atoms enable the determination of thenuclear spin and electromagnetic moment, respectively,
through the measurements of Zeeman splitting and hyperﬁne splitting (HFS). Even without the high energy
ion beams, by using the laser ablation technique, we can
supply stable isotope atoms into He II. We have successfully measured HFSs of alkali atoms, 85, 87 Rb and 133 Cs
in He II.1,2) Consequently, we found that the HFSs differ from the ones in vacuum by a little less than 1% andthe achieved precision was suﬃcient even for the studyof hyperﬁne anomalies. Currently, we are attempting toapply this method to group 11 atoms to verify whether
a similar diﬀerence appears in atoms other than alkali
metal elements. The HFS of the stable isotope 197 Au
atom in He II was measured using this technique.3) Todiscuss the diﬀerential hyperﬁne anomalies 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, whose natural abundance
ratio is almost 1:1. Previously, however, we faced difﬁculties in the preparation of Ag atoms in He II.4) In
this report, we describe how we solved this problem.
In oﬄine experiments, atoms are introduced into He
II by laser ablation and laser dissociation. As the ﬁrst
step, a metal sample placed above He II surface is ablated by a second-harmonic pulse of a Nd:YAG laser
in the same manner as Ref. 4). Only Ag clusters,
among the particles generated by the ablation, can be
immersed into He II because the energy barrier for athermalized atom is too high to penetrate the surfaceof liquid helium. Next, the clusters are required to bedissociated by a dissociation laser to produce atoms forthe application of our spectroscopic technique. If dissociation occurs, highly excited atoms are generated andthe plasma emission from those atoms should be observed. When we used a femtosecond Ti:Sa laser for
Ag atoms, however, even plasma emission was not observed, as reported in Ref. 4).
It has been reported that Ag clusters in superﬂuid

LIF Intensity [counts / bin]

W. Kobayashi,∗1,∗2 K. Imamura,∗1,∗3 M. Sanjo,∗1,∗2 T. Fujita,∗1,∗4 A. Takamine,∗1 T. Furukawa,∗5 H. Ueno,∗1
and Y. Matsuo∗1,∗2

-3
1000

Sweep Time [ms]Fig. 1. Variation of LIF intensity with sweeping a magnetic
field.

helium droplets have an absorption at the around 330–
360 nm instead of 800 nm.5) Considering this characteristic of Ag clusters, we used the third-harmonic pulseof Nd:YAG laser (wavelength: 355 nm, repetition rate:
20 Hz, pulse width: 5 ns, pulse energy: 8 mJ) for the
dissociation. Consequently, plasma emission was observed. From this result, it was revealed that laser
wavelength selection is crucial for the dissociation of
Ag clusters, which was not the case for Rb, Cs, and Auclusters.
Next, we generated spin polarization by an opticalpumping method. The Ag atoms in He II were optically pumped and polarized by irradiation with a circularly polarized pumping laser, which was the fourthharmonic pulse of a neodymium-doped yttrium vanadium oxide (Nd:YVO4 ) laser (wavelength: 335.5 nm,
repetition rate: 20 kHz, pulse width: ∼25 ns, pulse
energy ∼1.5 µJ). When optical pumping is achieved,
the intensity of laser-induced ﬂuorescence (LIF) due
to the pumping laser is decreased because we optically
pumped the atoms into a dark state. Spin polarization
was conﬁrmed by the observation of the variation in
LIF intensity while sweeping a magnetic ﬁeld (0–12 G).
Figure 1 shows the decrease in LIF intensity when asuﬃcient magnetic ﬁeld was applied. We preliminarily
conﬁrmed from this spectrum that we achieved a spinpolarization of 50%. This result also leads to the conclusion that we successfully introduced Ag atoms into
He II and observed LIF. The HFS measurement for Ag
atoms in He II is in progress.
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 (2017).
5) E. Loginov et al., Phys. Rev. Lett. 106, 233401 (2011).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Magnetic properties of Alkali-metal Superoxide, NaO2
F. Astuti,∗1,∗2 M. Miyajima,∗3 T. Kambe,∗3 T. Nakano,∗4 and I. Watanabe∗1,∗2
Magnetism in the p-electron system has attracted
attention for the possibility of new types of magnetic
informative materials. Alkali-metal superoxides, AO2(A = Na, K, Rb, Cs), present an interesting example of magnetic materials on the basis of unpaired pelectrons. The magnetic ordering of KO2 , RbO2 , andCsO2 have been observed at temperatures 7 K, 15 K,
and 9.6 K, respectively using specific heat.1) However,
the magnetic ground state in NaO2 is not yet clarified.
Clear anomalies from the measurement of magnetic
susceptibility were observed at a temperature between
230 and 200 K in NaO2 . These anomalies were consistent with the expected structural phase transition, as
discussed in the previous study.1) The magnetic susceptibility, χ, drops sharply below 40 K, as shownin Fig. 2 (a). We checked that the sample quality
was good and the anomalies in magnetic susceptibility could be reproduced in all NaO2 sample batches(see sample condition in Fig. 1). The sudden changeof susceptibility value toward zero is an indication ofspin gap state as observed in other spin gap systems,
NaTiSi2 O6 and TiOCl.2,3) Mahanti et al. reported that
NaO2 has some similarities with one-dimensional spin
system.4)
There was no emergence of muon-spin precession
from the previous zero-field (ZF) µSR experiment in
NaO2 down to 0.3 K measured at the RIKEN-RAL
Muon Facility and DOLLY PSI, which indicated theabsence of magnetic ordering. To further study themagnetic properties in NaO2 , we measured the depolarization rate in ZF close to anomaly ∼ 40 K (observed by magnetic susceptibility) using CHRONUS
spectrometer at the RIKEN-RAL Muon Facility.
The temperature dependence of exponential relaxation rate, λ, measured using ZF- µSR showed ananomaly at a temperature below 40 K that was significantly consistent with the anomaly observed bymagnetic susceptibility measurement, as shown in
Fig. 2 (a). This indicated the possibility of magnetictransition around this temperature.5) The red line in
Fig. 2 (b) is the fitting line that utilizes the following
function: λ(T) = λ0 /[1 + A exp( −2∆T )], in which A isthe constant and ∆ is the spin-gap value.6) The obtained result of ∆ is estimated to be ∼ 35 K. The possibility of the formation of spin gap in NaO2 must be
further explored using other experimental techniques.
∗1
∗2
∗3
∗4

Fig. 1. Some sample batches of NaO2 used for µSR experiment. Labels indicate the number of sample batches.
Bright and dense yellow color imply that sample quality
is good.

Fig. 2. (a) Magnetic susceptibility of NaO2 and (b) Temperature dependence of exponential relaxation rate, λ,measured using ZF-µSR at various temperature aboveand below 40 K.

References
1) A. Zumsteg et al., Phys. Cond. Matter 17, 267–291(1974).
2) M. Isobe et al., J. Phys. Soc. Jpn, 71, 1423 (2002).
3) A. Seidel et al., Phys. Rev. B 67, 020405(R) (2002).
4) S. D. Mahanti et al., Solid State Commun. 18, 159–162(1976).
5) S. J. Blundell et al., J. Phys. Condens. Matt. 9, 119(1997).
6) P. J. Baker et al., Phys. Rev. B 75, 094404 (2007).

Department of Condensed Matter Physics, Hokkaido University
RIKEN Nishina Center
Department of Physics, Okayama University
Graduate School of Science and Engineering, Ibaraki University- 20 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Mass spectrometric speciation of mononuclear Re carbonyls in the gas
phase
Y. Wang,∗1,∗2 Y. Wittwer,∗3,∗4 J. Zhang,∗2 J. Yang,∗2 H. Haba,∗1 Y. Komori,∗1 T. Yokokita,∗1 S. Cao,∗2 F. Fan,∗2
R. Eichler,∗3,∗4 A. Türler,∗4 and Z. Qin∗2
For the chemical characterization of bohrium carbonyls, Bh(CO)n , a gas-phase chemical study of rhenium (Re) carbonyls was conducted at RIBF, RIKEN.1)
However, the experiments provided low chemical yields,
making it necessary to further study the formationof mononuclear Re carbonyls. In this study, a laserablation time-of-flight mass-spectrometer (LA-TOFMS) was modified to obtain the mass spectra of mononuclear Re carbonyl ions. High-purity CO and He gas mixtures were used to deduce the most stable species. Moreover, the influence of impurities on the formation of the
carbonyls was also investigated by adding O2 and H2 tothe gas mixture, because both were expected to have asignificant influence on Re.2)
Figure 1 shows the schematic of our LA-TOF-MS
setup. Each measurement starts with the pulse valve
opening (120 µs), thereby releasing a supersonic gas
jet. The gas is directed over the target surface, wherean ablation laser (Nd: YAG laser, 532 nm, 10 Hz,
15 mJ/pulse) induces a plasma to generate free metal
atoms and ions. Some of the plasma is rapidly cooledby the gas. Then it is transported through a skimmer
to a positive electric field, where a short pulsed highvoltage is applied (20 µs, 10 Hz, +1400 V). After free
drifting, the cations reach a micro-channel plate (MCP)
detector and the flight time is measured. An extension
pipe (i.d. = 4 mm; length = 60 mm) is added downstream of the metal target in to increase the reaction
time and strengthen the interaction between Re ions andCO gas. This was done to identify the most stable products formed in the gas phases, which are similar to thoseof our gas chromatography experiment.1,3)

∗2
∗3
∗4

Because the ion mass is proportional to the squareroot of its flight time, the mass number of each cation
can be determined, and then the chemical formula canbe deduced. Using He seeded by CO (CCO = 14%) as
the carrier gas, Re+ and [Re(CO)6 ]+ ions can be clearly
identified in the mass spectrum. No intermediates orother products can be observed owing to the added extension pipe. Then, H2 , O2 , and H2 /O2 gas mixtures
are added to the carrier gas as impurities. Only few[Re(CO)5 · (H2 )]+ can be observed when 14% of H2 isadded to the carrier gas. No other Re carbonyl hydrides
appear when C H2 is lower than 5%, while large amountof [ReO2 · (CO)4 ]+ can be observed when O2 is added tothe carrier gas. Therefore, H2 does not have a significant
influence on the formation of [Re(CO)n ]+ . The mass
spectra of O2 gas mixtures are very similar to Fig. 2.
Figure 2 shows the mass spectra of adding H2 and O2
to the CO and He carrier gas (C CO was fixed at 14%;
C H2 and C O2 varied from 14% to 0.002% in the same
steps). Despite the small quantities of hydroxides visible in both figures, the only significant reaction products
are [ReO2 · (CO)4 ]+ and [Re(CO)6 ]+ . [ReO2 · (CO)4 ]+disappears completely when C O2 is 0.002%. Therefore,
we conclude that the formation of Re carbonyl ions is
not sensitive to trace amounts of H2 , while even 0.09%
of O2 will significantly increase the product yield of Re
carbonyl oxide ions and decrease the product yield of Re
carbonyl ions.
References

Fig. 1. Schematic of the LA-TOF-MS technique.
∗1

Fig. 2. Mass spectra with a Re target using H2 and O2 in
CO and He gas mixture (C CO is 14%, while both C H2
and C O2 vary from 14% to 0.002% in the same steps).

RIKEN Nishina Center
Institute of Modern Physics, Chinese Academy of Sciences
Laboratory of Radiochemistry, Paul Scherrer InstituteDepartment of Chemistry and Biochemistry, University ofBern- 21 -

1) Y. Wang et al., RIKEN Accel. Prog. Rep. 50, 25 (2017).
2) Y. Wang et al., Phys. Chem. Chem. Phys. 17, 13228(2015).
3) Y. Wang et al., Phys. Chem. Chem. Phys. 21, 7147
(2019).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Practical synthesis of 211 At-labeled immunoconjugate by double click
method for α-emission cancer radiotherapeutics†
K. Fujiki,∗1,∗2 Y. Kanayama,∗3 S. Yano,∗4 N. Sato,∗4 T. Yokokita,∗4 P. Ahmadi,∗1,∗2 Y. Watanabe,∗3 H. Haba,∗4
and K. Tanaka∗1,∗2,∗5
In this paper, a facile synthesis of an 211 At-labeledimmunoconjugate that is used as an α-emission molecular targeting therapy is described. We synthesizeda tetrazine probe modiﬁed with closo-decaborate(2-),
which is a prosthetic group that forms a bioavailable stable complex with 211 At. Our one-pot three-component
double-click labeling method,1) which consists of RIKEN
click2–4) and tetrazine ligation,5) was utilized to introduce the decaborate to HSA (human serum albumin) or
trastuzumab (anti-HER2 antibody) using decaboratetetrazine 1 and TCO (trans-cyclooctene)-aldehyde 2
without reducing the antibody binding aﬃnity, as shownin Fig. 1. The average number of molecules attached
to HSA was determined as 2 decaborate moieties (a1 + 2 molecule underwent a 1,065 MW increase) by the
MALDI-TOF mass spectroscopic analysis in comparison
to the intact HSA molecular weight.
Next, the astatination of decaborate-trastuzumab
was conducted by treating solutions of decaboratetrastuzumab with Na[211 At] in the presence of chloramine T as an oxidant over 5 min at room temperature. As shown in Fig. 2, the labeling was performed
using 1 µM decaborate-trastuzumab in 0.05% PBS-T
and Na[211 At], 75 MBq, in PBS to furnish 211 At-labeledtrastuzumab with a speciﬁc activity of 1.7 MBq/µg in
49% RCY. The potential loss of antigen recognition activity in the 211 At-labeled trastuzumab with a high speciﬁc activity was assessed by measuring the dissociation

Fig. 1. Preparation of decaborate-HSA/trastuzumab via
the one-pot three-component double-click labelingmethod. Dissociation constants (Kd ) of the decaboratetrastuzumab measured by the QCM method.
†

∗1
∗2
∗3
∗4
∗5

Condensed from the article in Chem. Sci. 10, 1936 (2019)
Biofunctional Synthetic Chemistry Laboratory, RIKEN
GlycoTargeting Research Laboratory, RIKENLaboratory for Pathophysiological and Health Science,
RIKEN
RIKEN Nishina Center
Biofunctional Chemistry Laboratory, Kazan Federal University- 22 -

constant Kd of the obtained 211 At-labeled trastuzumab.
This value was found to be 1.0 nM, indicating no impairment to the aﬃnity. Reacting 0.1 µM decaboratetrastuzumab with Na[211 At], 104 MBq, in PBS provided
211
At-labeled trastuzumab in 30% RCY with a very highspeciﬁc activity of 15 MBq/µg.
An intratumor injection of 6.3 µg of the 211 At-labeledtrastuzumab with 1.4 MBq in BALB/c nude mice implanted with HER2-expressing epidermoid cancer cells
yielded eﬀective suppression of tumor growth, as shownin Fig. 3. Our work provides one of the most practical 211 At-labeling methods to develop molecular cancer
radiotherapeutics.

Fig. 2. Radiolabeling of decaborate-trastuzumab. RCY (Radiochemical yield) was obtained from the radioactivityof the puriﬁed radiolabeled product against the added
Na[211 At].

Fig. 3. Therapeutic eﬃcacies of α-emitting 211 At-labeledtrastuzumab, trastuzumab, or PBS after intratumor injection.

References
1) K. Fujiki et al., Sci. Rep. 7, 1912 (2017).
2) K. Tanaka et al., Angew. Chem. Int. Ed. 47, 102 (2008).
3) K. Tanaka et al., Angew. Chem. Int. Ed. 49, 8195 (2010).
4) K. Fujiki, K. Tanaka, e-EROS Encyclopedia of Reagentsfor Organic Synthesis (Wiley, Germany, 2018), published
online. DOI: 10.1002/047084289X.rn02050
5) M. L. Blackman, M. Royzen, J. M. Fox, J. Am. Chem.
Soc. 130, 13518 (2008).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Activation cross sections of α-induced reactions on nat Zn for Ge and
Ga production†
M. Aikawa,∗1,∗2 M. Saito,∗3,∗2,∗4 S. Ebata,∗1,∗5 Y. Komori,∗2 and H. Haba∗2
Gallium-68 (T1/2 = 67.71 min) is used in positronemission tomography (PET). The production of 68 Ga
is important for its application in PET. In addition
to 68 Ga, the production of its long-lived parent, 68 Ge(T1/2 = 270.95 d), is worthy of investigation for a 68 Ga
generator. One of the reactions to produce 68 Ge is the
α-induced reaction on nat Zn. Two sets of experimental data1,2) could be found in the EXchange FORmat(EXFOR) library. The two datasets deviate from eachother. Therefore, we measured the cross sections of
α-induced reactions on nat Zn for 68 Ge production.
The experiment was performed at the AVF cyclotronof the RIKEN RI Beam Factory using standard methods, stacked foil activation method, and oﬀ-line γ-ray
spectrometry. Thin metallic foils of nat Zn (99.9% purity, Nilaco Corp., Japan) and nat Ti (99.6% purity, Nilaco Corp., Japan) were stacked as the target. The
stacked target was irradiated by a 51.5 MeV α beam.
The incident beam energy was measured by the timeof-ﬂight method using a plastic scintillator monitor.3)
The irradiation of the α beam lasted for 2 hours. The
average intensity was 82.0 nA, which was measured bya Faraday cup. The decrease in the energy of projectiles in the target was estimated using the SRIM
code.4) γ spectra from the irradiated foils were measured with a high-resolution HPGe detector.
To assess the beam parameters and target thicknesses, the cross sections of the nat Ti(α, x)51 Cr monitor reaction were derived. Consequently, we could conﬁrm that our results were signiﬁcantly consistent withthe recommended values.5)
The 1077.34-keV γ-line (Iγ = 3.22%) from the 68 Ga
decay was measured after a long cooling time of approximately 80 days. Directly produced 68 Ga could
completely get decayed in this period and the decay of
68
Ga was in equilibrium with that of its parent 68 Ge.
The cross sections of 68 Ge are shown in Fig. 1 with previous experimental data1,2) and TENDL-2017 data.6)
The peak position of our result is consistent with theexperimental data, although the amplitude is slightly
larger. The tendency of TENDL-2017 data is diﬀerent
from the experimental data.
The integral yield of 68 Ge was estimated from the
†
∗1
∗2
∗3
∗4
∗5

nat

Cross section (mb)250

Haasbroek+ (1976)
Nagame+ (1978)
TENDL2017
This work

Zn(α,x)68Ge

200
150
100
50
0

0

10

20

30

40

50

Energy (MeV)

Fig. 1. Excitation function of nat Zn(α, x)68 Ge reaction.

Integral yield (kBq/µAh)

100

68

Haasbroek+ (1976)
Nagame+ (1978)
This work

Ge

80
60
40
20
0

10

15

20

25

30 35 40
Energy (MeV)

45

50

55

Fig. 2. Integral yield of 68 Ge.

cross sections measured in this work and stopping powers calculated by the SRIM code.4) The derived integral yield is shown in Fig. 2 with the previously obtained experimental data.1,2) The values obtained inour result are greater than other data above 30 MeV
as expected from the cross sections measured in thiswork.
References
1) F. J. Haasbroek et al., CSIR Res. Rep. FIS 91, 1 (1976).
2) Y. Nagame et al., Int. J. Appl. Radiat. Isot. 29, 615(1978).
3) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566 (2014).
4) SRIM: the Stopping and Range of Ions in Matter, http://www.srim.org/.
5) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2017).
6) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 427, 91 (2018)
Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Science, Hokkaido University
Present address: Graduate School of Biomedical Science,
Hokkaido University
Present address: School of Environment and Society, Tokyo
Institute of Technology- 23 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

A novel mutation induced by Ar-ion-irradiation aﬀect grain length andimprove yield in rice
R. Morita,∗1 H. Ichida,∗1 Y. Hayashi,∗1 H. Abe,∗1 Y. Shirakawa,∗1 K. Ichinose,∗1 T. Kazama,∗2 K. Toriyama,∗2
T. Sato,∗1,∗2 and T. Abe∗1
Rice serves as an important staple food for morethan half of the world’s population. The size of a ricegrain, which is one of the most important agronomic
traits, is correlated with its yield. The grain size is apolygene-controlled quantitative trait, resulting in substantial variations in the size and shape of grains. Although several genes inﬂuencing the grain size have beencloned from rice cultivars, it is necessary to identify novel
genes that determine the grain size to meet the increasing food demands of the growing world population.
To identify a novel gene that can determine the grainsize, we isolated a rice mutant that exhibited a signiﬁcant increase in grain weight from 159 independent M2lines raised from Ar-ion-irradiated (5 Gy, 290 keVµm−1 )rice seeds. In the mutant, the grain length increased(5.46 ± 0.01 mm, Avr. ± SE) in comparison with thatof the wild-type (WT) Nipponbare (5.26 ± 0.02 mm,
Fig. 1). Given that the grain width and thickness were
not altered in the mutant, the increased grain weightwas considered to be the result of the increase in grain
length. We designated this mutant as long grain1 (lin1 ).
We tested whether the yield increased in the lin1 mutant under ﬁeld conditions in 2014 and 2016 in a paddy
ﬁeld. Three plots of the lin1 mutant and wild-type Nipponbare plants were formed in a paddy ﬁeld. In eachplot, 49 plants (7 × 7 plants, 30 cm inter-plant spacing)were planted. The outermost plants were excluded fromsampling to avoid the border eﬀect. Therefore, 25 plants(5 × 5 plants grown in the 1.44 m2 ) in the center of eachplot were used to calculate the yield. The 1000-grain
weight was 27.6 g and 25.9 g in 2014, and 27.1 g and26.3 g in 2016 in the lin1 mutant and Nipponbare, respectively (Table 1). The number of panicles, spikelets,and percentage fertility were not signiﬁcantly diﬀerent
between the lin1 mutant and WT in both years, suggesting that there was no tradeoﬀ between grain length

Fig. 1. Seeds and brown grains of Nipponbare (a and c) andlin1 mutant (b and d). Bar = 5 mm.
∗1∗2

RIKEN Nishina Center
Graduate School of Agricultural Science, Tohoku University

Table 1. Agronomic traits and grain yield of WT and lin1.

and number of panicles, number of spikelets, and percentage fertility in this mutant. Consequently, the grain
yield (g/m2 ) was 8.2% and 16.4% higher in the lin1 mutant compared with that of the WT in 2014 and 2016,
respectively. These results demonstrated that the mutated lin1 allele could improve the rice grain yield.
We performed the whole-genome sequencing and genetic linkage analyses to identify the yield-related gene,
LIN1. Thus, a 1 bp deletion in the coding sequence of
Os06g0675200 gene on chromosome 6 was ascertained
to be linked with the grain length. To conﬁrm that
Os06g0675200 corresponded with the LIN1 gene, we introduced a 1 bp insertion in the gene of Nipponbare using
the CRISPR/Cas9-mediated genome editing system. As
with the lin1 mutant, the transgenic plants displayed enhanced grain length compared with that of WT, thereby
indicating that the inactivation of the gene by the 1 bp
insertion and subsequent frameshift reproduced the observed phenotype of the lin1 mutant and supported theconclusion that Os06g0675200 is the LIN1 gene.
To investigate whether the mutant allele of LIN1 hasalready been utilized in rice breeding, we conducted
the sequence polymorphism analysis using the TASUKE
genome browser,1) which collectively provides polymorphisms among rice cultivars. We used information from
25 varieties (15 temperate japonica and ten indica), forwhich the sequencing coverage of the entire coding sequence of LIN1 was available. All temperate japonicaand six indica-varieties harbored the wild-type LIN1 allele. In contrast, four indica varieties shared an identical
T to C substitution, which caused a non-synonymous
substitution in the amino acid sequence of LIN1. These
results revealed that the increase in grain yield achievable by the inactivation of LIN1 might be limited in suchvariants that already harbor mutant LIN1 alleles. Thus,
the lin1 mutation reported in this study may be useful tofurther increase the grain yield in both temperate japonica and indica rice varieties.
Reference

1) M. Kumagai et al., Bioinformatics 29, 1806 (2013).
- 24 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Recent progress in overcoming interspecific hybrid sterility in rice
Y. Koide,∗1 K. Onishi,∗2 Y. Hayashi,∗3 T. Abe,∗3 Y. Fukuta,∗4 Y. Okumoto,∗5 and A. Kanazawa∗1
Inter-specific hybridization enables breeders totransfer valuable genes from one species to anotherfor improving crops. However, reproductive barriers,
which are also known as “species barriers,” often prevent gene flow between two species. In two cultivatedrice species (Oryza sativa and O. glaberrima), hybrid
sterility is considered as the main reproductive barrier.
To date, more than 10 loci for hybrid sterility between
these species have been found.1) Among these loci, the
HYBRID STERILITY 1 (S1 ) locus on the short armof chromosome 6 has been frequently detected,2) suggesting that the S1 locus is the major cause of thesterility barrier. Here, we review the recent progressin overcoming the hybrid sterility caused by the S1 locus and highlight the usefulness of a forward genetic
screening for a mutant with a “neutral” allele of hybrid
sterility loci.
In 1990, Sano3) showed that the hybrid between astrain of O. sativa and near-isogenic lines (NILs) containing a segment of chromosome 6 from O. glaberrimain the genetic background of O. sativa exhibited partial sterility in pollen and seeds. This phenomenon
was explained by the genetic interaction between the
S1g allele (formerly the S1 allele of Sano3) ) and S1s allele (formerly the S1a allele of Sano3) ), which were derived from O. glaberrima and O. sativa, respectively.
The S1g allele acts as a “gamete eliminator,” and bothmale and female gametes possessing the S1s allele areaborted only in the heterozygote (S1g /S1s ).4) Althoughthese studies revealed the genetic nature of the S1 locus, it was still unclear how we can overcome the sterility barrier.
Recently, significant progress has been made by artificial mutagenesis using genome editing5) or heavy-ion
beam irradiation.6) Koide et al.6) used Acc108 (a variety of O. sativa) and NIL, which contain the S1s allele
and the S1g allele at the S1 locus, respectively. Theyobtained a total of 2,478 F1 seeds for heavy-ion beamirradiation via artificial pollination. From 1,817 F1 hybrids (M1 generation) irradiated with carbon-ion beam
(LET 30 keV/nucleonm, 150 Gy) at the RIKEN RIbeam factory, Wako, Japan, they obtained one plantthat had a panicle with >50% seed fertility from theM1 population (Fig. 1). Then, they developed the M2
family through self-pollination of the M1 plant and obtained the mutant Acc108S1 M, which does not induce
∗1
∗2
∗3
∗4
∗5

A

NIL

B

Acc108x
S1s/S1s

S1g/S1g
F1

Heavy-ionbeam
irradiation

S1g/S1s

Select fertile plants

C>50%
seed ferlity
Acc108S1M

Fig. 1. Forward genetic screening for a mutant with a “neutral” allele of the hybrid sterility locus. (A) The scheme
for selecting a mutant with a neutral allele at the hybrid
sterility locus, S1 . (B) A sterile rice panicle observed in
the M1 plant. The seed sterility was due to the hybrid
sterility locus, S1 . (C) A fertile panicle observed in theM1 plant. Seed sterility did not occurr because of amutation induced at the S1 locus.

sterility in either the hybrid with the S1g carrier or thatwith the S1s carrier.
The results of the crossing experiments, genetic
mapping, and nucleotide sequencing suggested that thecausative mutation of Acc108S1 M was a 5-bp deletionin the peptidase-coding gene (denoted by SSP ) in the
S1 locus. These results indicated that the SSP was
one of the essential genes for inducing hybrid sterility
in heterozygotes (S1g /S1s ) and Acc108S1 M has a neutral allele “S1mut ” at the S1 locus.6)
In summary, recent studies5,6) have focused on the
S1 locus and have shown how to obtain a neutral allele
through reverse or forward genetic approaches. In general, the number of hybrid sterility loci that have beenannotated and characterized in crop gene pools is still
limited. In such a case, a forward genetic screening ismore practical than approaches in which gene identification is a prerequisite, e.g., genome editing, for creating neutral alleles. Although these two approaches
have their own specific advantages, recent studies havedemonstrated a technique that allows broader accessto desirable traits in distantly related species duringcrop breeding.
References
1) K. Doi et al., Curr. Opin. Plant Biol. 11, 144–148(2008).
2) A. Garavito et al., Genetics 185, 1425–1440 (2010).
3) Y. Sano, Genetics 125, 183–191 (1990).
4) Y. Koide et al., New Phytol. 179, 888–900 (2008).
5) Y. Xie et al., Mol. Plant 10, 1137–1140 (2017).
6) Y. Koide et al., Proc. Natl. Acad. Sci. USA, 115,
E1955–E1962 (2018).

Research Faculty of Agriculture, Hokkaido University
Department of Agro-Environmental Science, Obihiro University of Agriculture and Veterinary Medicine
RIKEN Nishina Center
Japan International Research Center for Agricultural Sciences
Faculty of Agriculture, Kyoto University- 25 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 52 (2019)

Improved and robust method to eﬃciently deplete repetitiveelements from complex plant genomes†
H. Ichida∗1 and T. Abe∗1
Wheat is one of the most important staple food crops
around the world, occupying 17% (one-sixth) of the
global crop acreage and serving as a food source forapproximately 40% of the world’s population. Despite
the availability of a high-quality reference genome sequence, whole genome re-sequencing of wheat is stilla major challenge owing to its large and complex
genome. Wheat has an estimated haploid genome sizeof 15.4–15.8 Gb, of which 84.7% is made up of repetitive sequences. To successfully apply genome sequencing to practical agricultural breeding situations, the establishment of an eﬀective strategy to eliminate highly
abundant repetitive elements within the genome is required.
Duplex-speciﬁc nuclease (DSN) provides an enzymatic method to reduce the whole-genome redundancy
and normalization. However, this method has notbeen widely used in the genome analysis of agricultural
crops owing to its sensitivity to reaction conditions anddiﬃculty in DNA recovery after the treatment. We developed an improved design for Illumina-compatible sequencing adapters that avoids duplex formation withina typical annealing temperature range (∼68◦ C) and accidental degradation by the DSN enzyme. The newly
designed adapter includes the 21 bp sequences immediately adjacent to the original TruSeq adapter andforms a hairpin-like structure by placing the necessary
adapter sequences in a complementary orientation at
the 5’ and 3’ ends of a single oligonucleotide at room
temperature during library preparation. Using this design, all necessary sequence elements for Illumina sequencing could then be added using full-length adapter
primers during the recovery PCR, which generates a library with exactly the same structure as the original
TruSeq libraries.
We compared the relative abundance of 18S and
25S rDNA elements in genomic DNA and the DNA
libraries before and after DSN treatment (DSN− andDSN+ , respectively) in rice and diploid, tetraploid,and hexaploid wheat cultivars by quantitative PCR.
In summary, the relative abundances of 18S and
25S rDNA were reduced to 1.15% and 3.54% of theDSN− samples in rice. The eﬀectiveness of the DSN
treatment was essentially the same among the threewheat genomes. In particular, the relative abundanceof 18S rDNA was decreased to 7.13%, 4.95%, and4.33% considering the DSN− in diploid, tetraploid, andhexaploid cultivars, respectively. The relative abun†∗1

Fig. 1. Comparison of read counts before and after duplexspecific nuclease-based repeat depletion in gene regions.
Reprinted from Plant Science, https://doi.org/10.
1016/j.plantsci.2018.10.021, with permission from
Elsevier.

dance of 25S rDNA was also decreased to 21.73%,
8.96%, and 7.54% considering DSN− . These results
indicate that the DSN treatment eﬀectively depleted
repetitive sequences in diﬀerent wheat cultivars, whichhave much larger and more complex genomes compared with rice.
We evaluated the enzymatic depletion of highly
repetitive elements by DSN treatment in an actual Illumina sequencing run using the diploid wheat cultivar KU104-1, which has an estimated genome size of
6.1 Gb, as a model. The sequencing reads mappedon the regions encoding Ty1-Copia and Ty3-Gypsy
were decreased by 61.6% and 33.4%, respectively, compared with the DSN− samples. DNA-type repetitive elements were also successfully depleted by the
DSN treatment. In particular, reads mapped to DNAtype transposons and simple sequence repeats (SSRs)
were respectively reduced by 17.1% and 9.0% compared with the untreated control. Therefore, we conclude that this method should be useful in a broad
range of species in which genomic approaches are notcurrently applicable owing to their large and complex
genome structures and the consequent high expenses
of sequencing and analysis.

Condensed from the article in Plant Science,
280, 455-460 (2019)
RIKEN Nishina Center- 26 -

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

1. Nuclear Physics

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Breakup of 9 C studied at SAMURAI
A. I. Chilug,∗1,∗2,∗3 V. Panin,∗3,∗4 L. Trache,∗1 T. Motobayashi,∗3 Z. Halasz,∗5 for HI-p collaboration
During the NP1412-SAMURAI29R1 experiment, theC breakup reaction into 8 B +p was studied by Coulomb
dissociation and nuclear breakup. By using the invariant
mass technique and the detailed balance theorem,1) it ispossible to determine the reaction cross section for the
astrophysical process 8 B(p, γ)9 C using two alternative
indirect methods: Coulomb dissociation1) and by applying the ANC technique for nuclear breakup (NB).2)
The radiative proton capture 8 B(p, γ)9 C is being investigated due to its astrophysical importance as a possible bypass of the 3α-process leading to the CNO cycle
in low metallicity massive stars, by a sequence of protons
and alpha capture reactions on nuclei close to the proton drip line.3) From the previous experiments, a large
spread of results was obtained for the determined astrophysical S18 factor (see Ref. 4)), and hence a new set of
accurate measurements is necessary.
The experiment was performed in RIKEN at the RIBF
facility during the SAMURAI Oxygen18 campaign in thespring of 2018, as part of the HI-p program. The primary beam 18 O at 230 AMeV hit a Be production target. The 9 C secondary beam, having intensities up to
4.7 · 104 pps, was separated by using the two-stage separator BigRIPS and delivered to the SAMURAI area.
Fig. 1 shows the PID of the beam at the entrance of
the SAMURAI area. The aim of the experiment is toperform inclusive and exclusive measurements of the 9 C
breakup reaction products using a dedicated detection
system set at the superconducting magnetic spectrometer SAMURAI. For the study of 9 C breakup in a nuclear
field, a natural carbon target (425 µm thick) was used,
and for the Coulomb dissociation measurement, we set
a Pb target (150 µm thick). The detection system usedduring the experiment comprised two scintillator detectors (SBT1&2) for beam PID (in combination with the
BigRIPS scintillators) and for triggering the data acquisition system. Two drift chambers (BDC1&2) were used
to measure the position and angle of the beam. The target was followed by 4 Si detectors to track the reaction
products along with another drift chamber (FDC0). Twoplastic scintillators (HODF&HODP) were placed behind
the SAMURAI exit window to measure the energy loss
and the time of flight for particle identification. Finally,
two proton drift chambers (PDC1&2) were used for magnetic rigidity analysis of the emitted protons.
The tracking system mentioned above is made of 4
position sensitive Si detectors (GLAST) with a large active area (87.5 × 87.5 mm2 ) and high granularity (eachsilicon detector has 128 strips), which were arranged in
two pairs, an placed downstream of the reaction target.
9

∗1
∗2
∗3
∗4
∗5

Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH)
Faculty of Physics, University of Bucharest
RIKEN Nishina Center
Département de Physique Nucléaire, IRFU, CEA, Université
Paris-Saclay
Institute of Nuclear Research (ATOMKI), DebrecenFig. 1. The purity and PID of the secondary beam.

Fig. 2. Signals of the reaction products in the Si system.

This system was newly introduced for all 4 HI-p experiments. In order to simultaneously track the protons andheavy fragments, the signals from the Si detectors were
processed with new Dual Gain Preamplifiers (DGP) designed at RIKEN and packed at ATOMKI. A high dynamic range was assured for the entire system. Thus,
the system could measure the energy loss of the protons(around 200 keV) in coincidence with the heavy fragments (up to 600 MeV). The signals from the DGP were
fed into the ASIC system based on HINP16 chips.5) Two
Motherboards (MB) with 16 slots each for connecting 16
HINP boards, each of them having 2 ASIC chips, processed a total of 1024 output signals from the silicondetectors. The PID of the reaction products in the Si
detectors can be seen in Fig. 2.
The Si system was used in the beam for the first time.
It worked well, and in combination with the existing
detection systems, assured the experimental goals presented in the submitted proposal. The data analysis isin progress.
References

1) G. Baur et al., Nucl. Phys. A 458, 188–204 (1986).
2) L. Trache et al., Phys. Rev. Lett. 87, 271102 (2001).
3) M. Wiescher et al., Astrophys. J. 343, 352–364 (1989).
4) T. Fukui et al., Few-body Syst. 54 1583–1586 (2013).
5) G. L. Engel et al., Nucl. Instrum. Methods Phys. Res. A
573, 418–426 (2007).

- 27 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Cluster structure of neutron-rich beryllium isotopes investigated bycluster quasi-free scattering reaction
P. Li∗1 and D. Beaumel∗2,∗3 for the SAMURAI12 collaboration
Clustering is known for long as an important andgeneral feature of atomic nuclei. So far alpha-particle
clustering has dominated cluster states studies among
all other possible partitioning. Thus, nuclei with evenand equal numbers of protons and neutrons (the socalled alpha-conjugate nuclei) have been extensively
studied. A few decades ago, some general propertiesof clustering in nuclei have been stressed, e.g. its preferential occurrence close to cluster decay thresholds
rather than in ground-states.1) The situation might besomewhat diﬀerent in exotic nuclei for which well developed cluster conﬁgurations may occur in groundstates, even though located well below the corresponding cluster threshold. The SAMURAI12 experiment
aims to investigate the cluster structure of neutronrich beryllium isotopes using the cluster quasifree scattering reaction (p, pα) in inverse kinematics. Such an
approach has been recently emphasized as a suitable
method to investigate how α cluster states are spatiallydeveloped.2) Beryllium isotopes are of special interestin relation with clustering. The 8 Be nucleus is famous
for its developed α–α structure, well reproduced by
ab initio calculations. Antisymmetrized Molecular dynamics calculations predict the occurrence of α–α core
up to the dripline, neutrons occupying molecular orbits
around this core. The purpose of the SAMURAI12 experiment is to study the (p, pα) reaction on neutronrich Beryllium isotopes up to the dripline.
The experiment was performed using the SAMURAI
large-acceptance spectrometer during the spring campaign of 2018. Secondary 10, 12, 14 Be beams at nearly
150A MeV were produced by fragmentation of a 230AMeV 18 O primary beam. using the BigRIPS separator. To study the (p, pα) reaction in inverse kinematics, a new setup combining several elements wasdeveloped. The ﬁrst component was the solid hydrogen target (SHT) system associated with the ESPRI
setup.4) This system allows to prepare a target foil oftypically 1–3 mm thickness with a diameter of 3 cm,
well adapted for our study. A new target chamber dedicated to the SAMURAI12 experiment has been builtwith new apertures allowing detection of protons at
the relevant angles. A new target frame was also built
for the production of a 2 mm thick foil which was usedin the experiment. For recoil proton detection, the
ESPRI Recoil Proton Spectrometer (RPS) system was
implemented. It is composed of 3 stages: 1. Multiwire
drift chamber (MWDC) for scattering angle determi∗1∗2∗3

nation, 2. plastic detector of 4 mm thickness and 3. NaI
rods. The system was installed in a two-arm conﬁguration identical to the one used during the SAMURAI13
experiment.4) The two arms were placed at 95 cm fromtarget, covering an angular range of 50◦ –70◦ , corresponding to about 40◦ –70◦ in center of mass (CM) for
the free p + α elastic scattering. Detection of alphaclusters was insured by two telescopes composed of Silicon and CsI(Tl) detectors placed at forward angles tocover the angular range 4◦ –12◦ . The ﬁrst layer wasa double-sided Silicon detector (DSSD), 62 × 62 mm
active area with 32 strips on each side. The second
stage was composed of CsI(Tl) crystals 2.5 × 2.5 cm2 ,6 cm long, from the FARCOS array. Energy range ofthe clusters was 100 ∼ 150 MeV/nucleon. A dedicatedenergy calibration run with a (secondary) alpha beam
was used in order to achieve precise energy calibrationneeded to deduce the missing mass. The detection of
the 4, 6, 8 He beam-like velocity residues near zero degrees produced in the 10, 12, 14 Be(p, pα) reactions was
performed using the SAMURAI spectrometer and its
standard detectors.5) The residue scattering angle wasmeasured using the Forward Drift Chamber 0 (FDC0)
placed upstream of the SAMURAI entrance. Afterthe exit window of SAMURAI, rigidity measurement
and particle identiﬁcation of the residues were insured
by the Forward Drift Chamber 2 (FDC2), and the
HODP and HODF walls of plastic hodoscopes composed of 16 and 24 slats of BC408 scintillators, (ofdimensions 120 × 10 × 1 cm3 ), respectively. For complementary invariant mass studies, the neutron multidetector NEBULA was also included in the setup. The
data analysis is undergoing, presently focusing on thecalibrations runs of forward telescopes with alpha secondary beams. A detailed uniformity response studyof CsI(Tl) modules is being performed owing to theposition information provided by the DSSD.
References
1) K. Ikeda, N. Tagikawa, H. Horiuchi, Prog. Theor. Phys.
464, (1968).
2) M. Lyu et al., Phys. Rev. C 97, 044612 (2018).
3) Y. Matsuda et al., Nucl. Instrum. Methods Phys. Res.
A 643, 6 (2011).
4) S. Chebotaryov et al., Prog. Theor. Exp. Phys. 2018,
053D01 (2018).
5) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).

Hong Kong University
Institut de Physique Nucléaire, Orsay
RIKEN Nishina Center- 28 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

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

Light output (a.u.)

HODF24 that were hit by the unreacted beam were excluded from the trigger. Figure 2 shows a typical PID
spectrum in HODF24 for events generated by the 11 Li
or 14 Be beams. Using the PID information, the reaction
channels for 11 Li(p, n)11 Be5) and 14 Be(p, n)14 B6) can be
identified.

11Li

Fig. 1. An incoming PID spectrum of the SBT detector. The
separation of 11 Li and 14 Be is clear.

∗1

Department of Physics, Kyushu University
Center for Nuclear Study, University of Tokyo∗3 RIKEN Nishina Center∗4 School of Physics, Peking University∗5 Horia Hulubei Nat. Inst. of Phys. and Nucl. Eng.
∗6 LPC CAEN
∗7 Department of Physics, Rikkyo University∗8 Department of Physics, Ewha Womans University∗9 ATOMKI, Institute for Nuclear Research, HAS∗10 Department of Physics, Toho University∗11 KVI - CART, University of Groningen∗12 GSI Helmholtzzentrum für Schwerionenforschung∗13 Department of Physics, Korea University∗14 Department of Physics, Tohoku University∗15 Dept. of Physics, Tokyo Institute of Technology∗16 Department of Physics, University of Tokyo∗17 Dépt. Physique Nucl., CEA, Univ. Paris-Saclay∗18 Dept. of Physics, Saitama University∗19 Institute of Modern Physics, Chinese Acad. of Sci.

14Be

Time-of-Fight (a.u.)Light output [MeVee]

The details of the particle identification (PID) of
the incoming secondary cocktail beam and the reaction
residues in the SAMURAI30 experiment are reported.
A secondary cocktail beam of unstable 11 Li and14
Be was produced via the fragmentation reaction of
a 230 MeV/nucleon 18 O primary beam on a 14-mmthick 9 Be target. In the experimental setup1) aroundthe SAMURAI spectrometer.2) two 1-mm-thick plastic scintillators (SBT1, 2) were installed for the detection of beam particles. The SBTs were used to produce the beam trigger (threshold was set to Z > 2).
The beam PID was performed on an event-by-event basis by measuring the energy loss in the SBTs and the
ToF of the beam particles in BigRIPS between F7 andF13. The secondary cocktail beam consisted of 11 Li at
182 MeV/nucleon with an intensity of 2.5 × 105 particle/s and 14 Be at 198 MeV/nucleon with an intensityof 1 × 105 particle/s with purities of 48% and 19%, respectively. The triton contamination was below 30%.
Figure 1 shows the incoming beam PID spectrum.
The secondary beam was transported onto a 10-mmthick liquid hydrogen target.3,4) The reaction residues
entered SAMURAI after passing through the forward
drift chamber, FDC0. The magnetic field of the spectrometer was set to 2.75 T. At the focal plane of SAMURAI, a wall (HODF24 detector) of 24 plastic scintillator
bars with dimensions of 1200W ×100H ×10D mm3 wasinstalled, to measure the trajectories, energy loss, andToF (from SBTs) of the reaction residues. Further downstream, an additional wall, HODP, with 16 plastic bars
(same as HODF24 bars) was installed. The 2 bars of∗2

fig Residue PID hod bar 7

80
70

11B

60
50

9Be

40
30

7Li

11Be

8Li

4He

10

2H

520

103

14Be

12Be

10Be

6Li

20

0
510

12B

11Li

102

9Li

6He

10

3H

530

540

550

560

1

Time-of-Fight (a.u.)

Fig. 2. A PID spectrum in the focal plane of SAMURAI,
measured by one bar (bar ID = 7) of HODF24.

References

1) M. Sasano et al., in this report.
2) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
3) X. Sun et al., in this report.
4) M. Miwa et al., in this report.
5) L. Stuhl et al., in this report.
6) J. Gao et al., in this report.
- 29 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Neutron-gamma separation performance of PANDORA in SAMURAI30
experiment
Y. Hirai,∗1 L. Stuhl,∗2 M. Sasano,∗3 J. Gao,∗3,∗4 K. Yako,∗2 T. Wakasa,∗1 D. S. Ahn,∗3 H. Baba,∗3 A. Chilug,∗5,∗3
S. Franchoo,∗6 Y. Fujino,∗7 J. Gibelin,∗6 I. S. Hahn,∗8 Z. Halász,∗9 T. Harada,∗10 M. N. Harakeh,∗11,∗12
D. Inomoto,∗1 T. Isobe,∗3 H. Kasahara,∗1 D. Kim,∗13 G. G. Kiss,∗9 T. Kobayashi,∗14 Y. Kondo,∗15 Z. Korkulu,∗3
S. Koyama,∗16 Y. Kubota,∗3 A. Kurihara,∗15 H. N. Liu,∗17 M. Matsumoto,∗15 S. Michimasa,∗2 H. Miki,∗15
M. Miwa,∗18 T. Motobayashi,∗3 T. Nakamura,∗15 M. Nishimura,∗3 H. Otsu,∗3 V. Panin,∗3 S. Park,∗8
A. T. Saito,∗15 H. Sakai,∗3 H. Sato,∗3 T. Shimada,∗15 Y. Shimizu,∗3 S. Shimoura,∗2 A. Spiridon,∗5 I. Stefanescu,∗5
X. Sun,∗3,∗4 Y. L. Sun,∗17 H. Suzuki,∗3 Y. Togano,∗7 T. Tomai,∗15,∗3 L. Trache,∗5 D. Tudor,∗5,∗3 T. Uesaka,∗3
H. Yamada,∗15 M. Yasuda,∗15 K. Yoneda,∗3 K. Yoshida,∗3 J. Zenihiro,∗3 and N. Zhang∗19,∗2

PSDmean (a.u.)(a)PSD o kevee 300

200< L.O.< 400 [keVee]

0.6
102
0.5

25

Counts

120
100
80
60

0.3
10
0.2

0.1

1500

2000

2500

3000

3500

4000

1

Light output [keVee]

Fig. 1. PSDmean as a function of light output (bar ID = 7).
∗1

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

20
15
10

40
5

20
0
0

0.1

0.2

0.3

0.4

PSDmean (a.u.)

0.5

0.6

0
0

0.1

0.2

0.3

0.4

PSDmean (a.u.)

0.5

0.6

Fig. 2. PSDmean distributions for the light output (a) from
200 to 400 and (b) from 1400 to 1600 [keVee]. The blue
and red lines shows gamma and neutron events, respectively.

the neutron-like events, while the distribution in the low
PSD range represents the gamma-like events.
To evaluate the discrimination performance of PANDORA, Figure-of-Merit (FoM)is used. FoM is deﬁned
as:
FoM =

1000

35
30

0.4

500

PSD o kevee 1500

1400< L.O.< 1600 [keVee]140

PSD vs Charge7

0
0

(b)

180
160

CountsThe neutron-gamma discrimination ability of PANDORA (Particle Analyzer Neutron Detector Of Realtime Acquisition )1) was studied for SAMURAI 302,3)
experiment using 11 Li(p, n) reactions.4) The method ofseparating neutron and gamma events is based on charge
integration, where the PSD (Pulse-Shape Discrimination) parameter is (QLong − QShort )/QLong , where QLong
and QShort are derived from the charge integrated in thelong gate and short gate of each end of a PANDORA
bar, respectively. PSDmean can be deﬁned as the arithmetic average of PSD because PANDORA is a doubleended read-out. Figure 1 presents a two-dimensional
plot of PSDmean vs. QLong (light output) of a PANDORA
bar. The locus in the higher PSD region corresponds to∆γ−n,
Lγ−FWHM + Ln−FWHM(1)where ∆γ−n is the PSD diﬀerence between the neutron and gamma component peaks. Lγ−FWHM and
Ln−FWHM are the full widths at half maxima of the
gamma and neutron distributions, respectively. In thiswork, we used the window method, detailed in Ref. 1).
Figure 2 shows the one-dimensional PSDmean projections in 200 keVee wide window centered at light outputs of 300 keVee (a) and 1500 keVee (b), respectively.
The calculated FoM values are 1.17 ± 0.01 (a) and
0.98 ± 0.03(b).We achieved better FoM value than previous studies.5–7) Owing to the optimized digital read-out,large gain setting, and improved scintillation material,
we achieved better FoM value than previous studies.
References
1) L. Stuhl, et al., Nucl. Instrum. Methods Phys. Res. A
866, 164 (2017).
2) M. Sasano et al., in this report.
3) L. Stuhl et al., in this report.
4) Y. Hirai et al., in this report.
5) S. A. Pozzi, et al., Nucl. Instrum. Methods Phys. Res. A
723, 19 (2013).
6) D. Cester, et al., Nucl. Instrum. Methods Phys. Res. A
735, 202 (2014).
7) P. Blanc, et al., Nucl. Instrum. Methods Phys. Res. A
750, 1 (2014).

- 30 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Gamow-Teller resonance in 14 Be(p, n) reaction
J. Gao,∗1,∗3 L. Stuhl,∗2 M. Sasano,∗1 Y. Hirai,∗4 K. Yako,∗2 T. Wakasa,∗4 for SAMURAI30 Collaboration
A charge-change (p, n) experiment, SAMURAI30,
on 14 Be and 11 Li nuclei was performed on the SAMURAI spectrometer.1,2) In this report, we present thestatus of the analysis of 14 Be(p, n)14 B∗ channel.
We used inverse kinematics with a secondary beamof 14 Be at 198.4 MeV/nucleon and a 10 mm thick liquidhydrogen target, rotated by 45◦ .3,4) The low-energy
neutron detector setup, consisted of PANDORA5) and
WINDS scintillator arrays, covered the laboratory angular range of 47.8◦ to 133.9◦ and were employed todetect the recoil neutrons. Signals from those detectors were recorded by a digital data acquisition system, which was operated in parallel with the standard
SAMURAI DAQ system by sharing the same trigger
signal.6) The neutron time-of-ﬂight was measured toreconstruct the missing mass spectra.
Figure 1 shows the laboratory angle vs. laboratory
energy spectrum of the detected neutrons when 13 B isselected in the HODF24 hodoscope, three curves (in
0–5 MeV, 5–10 MeV, and 15–20 MeV of excitation energies) evidently appeared. The left and right wingsof the scintilator array are drawn seperately. The colored solid lines indicate the excitation energy of 14 B.
The dotted lines indicate the corresponding center-ofmass angles. The signal-to-noise ratio is expected to be
improved by the neutron-gamma discrimination analysis.7)

Fig. 2. Kinematic correlation of neutron angle and energy
when 12 Be and deuteron are detected downstream of
SAMURAI.

Figure 2 shows the laboratory angle vs. laboratory energy spectrum of neutrons when both 12 Be anddeuteron are selected in the HODF24 hodoscope.
These curves show that the 14 B excitation energy
can be derived from the missing mass sprctrum ofneutrons, thereby implying that our experiment was
successfully performed. In the future, we will tag theother decay channels of excited 14 B and ﬁnally derive
the Gamow-Teller strength.
We express our gratitude to the RIKEN and CNS
staﬀ for the stable operation of the accelerators during
the measurement. This work is funded by the China
Scholarship Council, KAKENHI project 16H06716,
the Japan Society for the Promotion of Science, andKurata Grant from the Kurata Memorial Hitachi Science and Technology Foundation.
References
1) M. Sasano et al., in this report.
2) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294(2013).
3) M. Miwa et al., in this report.
4) X. Sun et al., in this report.
5) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A
866, 164 (2017).
6) J. Gao et al., in this report.
7) Y. Hirai et al., in this report.

Fig. 1. Kinematic correlation of neutron angle and energy
when 13 B is detected downstream of SAMURAI.

∗1

∗2
∗3
∗4

RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo
School of Physics, Peking University
Department of Physics, Kyushu University- 31 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Systematic study of one-proton and two-proton knockout reactions by
deuterium target
M. Miwa,∗1,∗2 T. Uesaka,∗2 Y. Kubota,∗3 H. Wang,∗2 P. Doornenbal,∗2 A. Obertelli,∗3 H. Otsu,∗2
and for the SEASTAR Collaboration

∗1
∗2
∗3

Department of Physics, Saitama University
RIKEN Nishina Center
Institut für Kernphysik, Technische Universität Darmstadt- 32 -

8

6

Sigma_d/Sigma_p

Roy J. Glauber1) ﬁrst stated that an additive law does
not always hold true in nuclear reactions. He showedthat the interaction cross-sections in deuteron induced
reactions are smaller than the sum of those in protonand neutron-induced reactions under the same conditions. The reduction in cross-section is due to hiding
one nucleon from the other in the target nucleus. Thisis called an “eclipse” eﬀect.
This eﬀect is thoroughly investigated for the interaction cross-section but not for individual reaction channels. In this work, we investigate the deuteron and proton induced one-proton and two-proton knockout reactions for neutron-rich beams and discuss their systematic
behavior.
The experiment was performed after the third
SEASTAR campaign4) in May 2017, using the SAMURAI spectrometer and MINOS target. A cocktail beamincluding neutron-rich K, Ca, Sc, Ti, and V was produced through projectile fragmentation reactions of a
primary 70 Zn beam at 345 MeV/nucleon impinging on aberyllium target. The experimental setup was the sameas that in the SEASTAR experiment, except that liquidhydrogen in the target container was replaced by liquid
deuterium. In the following analysis, we used the data
for liquid hydrogen as well. The liquid hydrogen anddeuterium targets with thicknesses of 1.1 and 2.6 g/cm2 ,respectively, were used as secondary targets. Beams of51
K, 52–54 Ca, 56–57 Sc, 58–60 Ti, and 61–62 V with an initial energy of ∼240 MeV/nucleon lost their energies by∼90 MeV/nucleon in the target. Therefore, the crosssections evaluated in this work are averaged over theenergy range. The secondary beam and fragments wereidentiﬁed event by event using the ∆E-TOF-Bρ method.
The systematic of interaction and one- and two-proton
knockout reactions for the neutron-rich beams were obtained. In the data analysis, the MINOS-TPC tracking
was not required and the cross-section was obtained bycounting the number of relevant isotopes in the focal
plane detectors of the SAMURAI spectrometer. Owing
to large acceptance of the SAMURAI spectrometer, allbeam particles and the products of one- and two-proton
knockout reactions were collected. Figure 1 summarizes
the data for the cross-section ratio of a deuteron target to a proton target plotted for nuclides in the cocktail beam. The green, blue, and red plots the represent interaction, one-, and two-proton knockout reaction cross-sections respectively. The ratios of interaction cross-sections had an almost constant value ∼1.2

4

2

0
51K 52Ca 53Ca 54Ca 55Sc 56Sc 57Sc 58Ti 59Ti 60Ti 61V 62V

IsotopeFig. 1. Ratio(σd /σp ) of cross-sections of a deuteron target toa proton target.The horizontal axis is the beam isotope.
The green, blue, and red plots represent the interaction,
one-proton, and two-proton knockout the reaction crosssections respectively.

for all isotopes. This is qualitatively attributed to theeclipse eﬀect as mentioned above. The ratios of oneproton knockout cross-sections had slightly larger values∼1.5. This is due to the diﬀerence in elementary processes. The cross-sections for p-n scattering were 60%
larger than those for p-p scattering. Thus, the crosssection comprising deuterium and a neutron is larger
than that of hydrogen. It should be to noted that theratios of interaction and one-proton knockout reaction
cross-section exhibited very small isotope dependences.
In contrast, the result of two-proton knockout crosssections shows a signiﬁcantly large deuteron/proton ratio. This value cannot be understood by the eclipse effect and/or the diﬀerence in elementary processes. We
presume it originates from unknown mechanisms, whichmight enhance the cross-section of two-proton knockoutwith a deuterium target. Practically, the large values
indicate the usefulness of a deuterium target in the production of neutron-rich nuclei via two-proton knockout
reactions.
the data for neutron knockout reactions and channels with one and more neutron evaporation were also
recorded. The systematic data can provide a comprehensive understanding of deuteron induced reactions.
References

1) R. J. Glauber, Phys. Rev. 100, 242 (1955).
2) A. Obertelli et al., Eur. Phys. J. A 50, 8 (2014).
3) H. Wang et al., Phys. Lett. B 754, 104 (2016).
4) P. Doornenbal, A. Obertelli, RIKEN Proposal for Scientific Program, (2013).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Study of spin-isospin response of 11 Li (SAMURAI30 experiment)
L. Stuhl,∗1 M. Sasano,∗2 J. Gao,∗2,∗3 Y. Hirai,∗4 K. Yako,∗1 T. Wakasa,∗4 D. S. Ahn,∗2 H. Baba,∗2 A. 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
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. 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,∗1th vs. Tn left

The spin-isospin responses of 11 Li and 14 Be neutron
drip line nuclei were measured in charge-exchange (p, n)reactions. Until recently, only the spin-isospin collectivity in stable isotopes was investigated.1) There is noavailable data for nuclei with large isospin asymmetry
factors, where (N − Z)/A >0.25. The (p, n) reactions atintermediate beam energies (E/A >100 MeV) and small
scattering angles can excite Gamow-Teller (GT) states
up to high excitation energies in the final nucleus, without Q-value limitation. The combined setup of PANDORA2) and SAMURAI spectrometer3) with a thick liquid hydrogen target (LHT)4) allowed us to perform theexperiment with high luminosity. In this setup,5) PANDORA was used for the detection of the recoil neutrons
while SAMURAI was used to tag the decay channel ofthe reaction residues.
The secondary cocktail beam of 11 Li and 14 Be wastransported onto the 10 mm-thick LHT.6) The neutron
detector setup on the left and right sides of LHT consisted of 27 PANDORA and 13 WINDS7) plastic scintillator bars. The neutron kinetic energies were deduced by
the time-of-flight (ToF) technique (1.25 m flight path).
The ToF time reference was taken from SBT1,2 plastic
scintillators. The left and right wings with respect to thebeam line covered the laboratory recoil angular regionof 47◦ –113◦ and 62◦ –134◦ , respectively, with 3.25◦ steps.
PANDORA was optimized to detect neutrons with a kinetic energy of 0.1–5 MeV. The light output threshold
was set to be 60 keVee . The digital data-acquisition(DAQ) of PANDORA was combined8) with standard∗1

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

Fig. 1. Recoil neutron energy spectrum as a function of scattering angle in the laboratory frame.

DAQ of SAMURAI.
The reaction residues were momentum analyzed
by the SAMURAI spectrometer, using HODF24 and
HODP detectors.9) Figure 1 shows a preliminary plotof kinetic energy as a function of laboratory scattering angle for recoil neutrons associated with 11 Li beam.
We required the simultaneous detection of 9 Li and d in
HODF24 and neutron detection10) in PANDORA.
A clear kinematical correlation between the measured
kinetic energy and the laboratory scattering angle, above
18 MeV excitation energy (Ex ), was obtained. This forward scattering peak (2◦ –7◦ in the center-of-mass system) suggests a GT transition. The 9 Li + d decay channel of 11 Be is observed for the first time. Reconstructionof the excitation-energy spectrum up to about 30 MeV,
including the GT giant resonance region, is ongoing.
References

1) K. Nakayama et al., Phys. Lett. B 114, 217(1982).
2) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A 866,
164 (2017).
3) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
4) X. Sun et al., in this report.
5) M. Sasano et al., in this report.
6) M. Miwa et al., in this report.
7) K. Yako et al., RIKEN Accel. Prog. Rep. 45, 137 (2012).
8) J. Gao et al., in this report.
9) Y. Hirai et al., in this report.
10) Y. Hirai et al., in this report.
- 33 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Overview of the experimental setup of SAMURAI30 to measure the11
Li(p, n) reaction in inverse kinematics
M. Sasano,∗1 L. Stuhl,∗2 J. Gao,∗1,∗3 Y. Hirai,∗4 K. Yako,∗2 T. Wakasa,∗4 D. S. Ahn,∗1 H. Baba,∗1 A. Chilug,∗5,∗1
S. Franchoo,∗6 Y. Fujino,∗7 J. Gibelin,∗6 I. S. Hahn,∗8 Z. Halász,∗9 T. Harada,∗10 M. N. Harakeh,∗11,∗12
D. Inomoto,∗4 T. Isobe,∗1 H. Kasahara,∗4 D. Kim,∗13 G. G. Kiss,∗9 T. Kobayashi,∗14 Y. Kondo,∗15 Z. Korkulu,∗1
S. Koyama,∗16 Y. Kubota,∗1 A. Kurihara,∗15 H. N. Liu,∗17 M. Matsumoto,∗15 S. Michimasa,∗2 H. Miki,∗15
M. Miwa,∗18 T. Motobayashi,∗1 T. Nakamura,∗15 M. Nishimura,∗1 H. Otsu,∗1 V. Panin,∗1 S. Park,∗8
A. T. Saito,∗15 H. Sakai,∗1 H. Sato,∗1 T. Shimada,∗15 Y. Shimizu,∗1 S. Shimoura,∗2 A. Spiridon,∗5 I. Stefanescu,∗5
X. Sun,∗1,∗3 Y. L. Sun,∗17 H. Suzuki,∗1 Y. Togano,∗7 T. Tomai,∗15,∗1 L. Trache,∗5 D. Tudor,∗5,∗1 T. Uesaka,∗1
H. Yamada,∗15 M. Yasuda,∗15 K. Yoneda,∗1 K. Yoshida,∗1 J. Zenihiro,∗1 and N. Zhang∗19,∗2
In this report, we provide an overview of the setup
used in the SAMURAI30 experiment performed at the
RI Beam Factory (RIBF) of RIKEN Nishina Center inthe spring of 2018.
The experiment was performed to measure the (p, n)reaction on 11 Li1) and 14 Be.2) A secondary cocktail
beam was produced via the fragmentation reaction of
a 230 MeV/nucleon 18 O primary beam on a 14 mmthick 9 Be target installed at the F0 focal plane of
the BigRIPS separator. The secondary cocktail beam
consisted of 11 Li at 182 MeV/nucleon and 14 Be at
198 MeV/nucleon with purities of 48% and 19%, respectively. The total beam intensity was 5 × 105 particle/s.
The SAMURAI spectrometer3) was used as the key
device to tag the (p, n) reaction channel through particle idenﬁcation of beam residual nuclei.4) The large
acceptance by the SAMURAI spectrometer was crucial
to detect a wide range of residual nuclei with diﬀerent
mass and proton numbers in the same setup.
Figure 1 shows a schematic view of the experimental setup around the SAMURAI spectrometer. Two 1mm-thick 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 (LH) target with a thickness and diameter of 10 and 60 mm,
respectively5,6) (rotated by 45◦ ) at the secondary target position of SAMURAI (F13).
∗1

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

Fig. 1. The schematic view of the experimental setup
around the SAMURAI spectrometer.

The PANDORA neutron detector setup consisted of
40 plastic scintillators and was placed on the left andright sides of the LH target. The neutron-gamma pulseshape discrimination (PSD) capability of PANDORA
in combination with a new DAQ system based on digitizers7) enables the reduction of the gamma-ray background originating from the enviroment as well as fromthe beam.8) PANDORA was optimized to detect neutrons with a kinetic energy of 0.1–5 MeV. The reaction
residues entered SAMURAI after passing through theforward drift chamber, FDC0. The magnetic ﬁeld of thespectrometer was set to 2.75 T. At the focal plane of
SAMURAI, walls consisting of 24 and 16 plastic scintillator bars, HODF24 and HODP, were installed to momentum analyze the reaction residues. NEBULA wasused to detect the fast decay neutrons of the reaction
products (decays by 1n and 2n emissions).
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) L. Stuhl et al., in this report.
2) J. Gao et al., in this report.
3) T. Kobayashi, et al., Nucl. Instrum. Methods Phys. Res.
B 317 294 (2013).
4) Y. Hirai et al., in this report.
5) X. Sun et al., in this report.
6) M. Miwa et al., in this report.
7) J. Gao et al., in this report.
8) Y. Hirai et al., in this report.

- 34 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Neutron-neutron correlation in Borromean nucleus 11 Li
via the (p, pn) reaction
Y. Kubota,∗1,∗2 A. Corsi,∗3 G. Authelet,∗3 H. Baba,∗2 C. Caesar,∗4 D. Calvet,∗3 A. Delbart,∗3 M. Dozono,∗1
J. Feng,∗5 F. Flavigny,∗6 J. -M. Gheller,∗3 J. Gibelin,∗7 A. Giganon,∗3 A. Gillibert,∗3 K. Hasegawa,∗8,∗2
T. Isobe,∗2 Y. Kanaya,∗9,∗2 S. Kawakami,∗9,∗2 D. Kim,∗10,∗2 Y. Kiyokawa,∗1 M. Kobayashi,∗1 N. Kobayashi,∗11
T. Kobayashi,∗8,∗2 Y. Kondo,∗12,∗2 Z. Korkulu,∗13,∗2 S. Koyama,∗11,∗2 V. Lapoux,∗3,∗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,∗1 H. Otsu,∗2 T. Ozaki,∗12,∗2 V. Panin,∗2 S. Paschalis,∗4
E. C. Pollacco,∗3 S. Reichert,∗16 J. -Y. Roussé,∗3 A. T. Saito,∗12,∗2 S. Sakaguchi,∗15,∗2 M. Sako,∗2
C. Santamaria,∗3,∗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 and J. Zenihiro∗2∗11d2σ/d kdcosθ nf (arb.)

Dineutron is a hypothetical bound state of two neutrons in a nuclear medium and spatially localized pair,which is diﬀerent from the one obtained via the BCS
mechanism.1) The neutron-neutron correlation from thedineutron is expected to appear in various circumstances such as the surface of weakly bound neutronrich systems and inner crust of the neutron stars. With
the advent of RI beam facilities, extended experimental
studies on the dineutron correlation on 11 Li have been
conducted such as E1 strength measurement using the
Coulomb breakup reaction2) and neutron momentum
measurement using the carbon-induced knockout reaction.3) Dineutron correlation has been experimentallyindicated through the smaller opening angle of two neutrons with respect to the core but its signature was integrated over the whole volume or limited region of thesystem owing to the methodology.4) The kinematicallycomplete measurement of the quasi-free (p, pn) reaction
was thus performed with 11 Li, 14 Be, and 17, 19 B to obtain the correlation angle θnf as well as the missing
momentum k, which provides radial information about
the neutron in its initial state.
The measurement was performed at RIBF using the
SAMURAI spectrometer.5) For higher statistics, the15-cm-thick liquid hydrogen target MINOS6) was usedwith a 200 kpps 11 Li beam. The (p, pn) setup composed of the neutron detector WINDS,7) recoil proton
detector, and gamma-ray detector array DALI28) was
newly conﬁgured to realize the kinematically complete

0.8

k ~ 0.3 fm -1
k ~ 0.7 fm -1

0.6
0.4
0.2
0
-1

-0.5
0
0.5
Correlation angle cosθ nf

1Fig. 1. cos θnf dependence of the double diﬀerential crosssection for each missing momentum k. The horizontal
and vertical axes show the correlation angle and double
diﬀerential cross-section, respectively. Each spectrum isscaled for the comparison. Errors are smaller than thesymbols.

measurement.
Figure 1 shows the cos θnf dependence of the double diﬀerential cross-section at k ∼ 0.3 and 0.7 fm−1 ,corresponding to the outer and inner part of 11 Li, respectively. The ﬁgure exhibits apparent k-dependenceof the correlation angle. The large negative slope atk ∼ 0.3 fm−1 is the signature of the dineutron correlation in this region. The slope is almost ﬂat atk ∼ 0.7 fm−1 , indicating a weak correlation. This result
reveals that the dineutron correlation is favored in theouter region of 11 Li, which is qualitatively consistent
with the theoretical predictions.1)
References

Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center∗3 CEA, Saclay∗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∗13 MTA Atomki∗14 Department of Physics, Kyoto University∗15 Department of Physics, Kyushu University∗16 Department of Physics, Technische Universität München∗21) A. B. Migdal, Soviet J. Nucl. Phys. 16, 238 (1973).
2) T. Nakamura et al., Phys. Rev. Lett. 96, 252502 (2006).
3) H. Simon et al., Phys. Rev. Lett. 83, 496 (1999).
4) Y. Kikuchi et al., Prog. Theor. Exp. Phys. 2016 103D03(2016).
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) J. Yasuda et al., Nucl. Instrum. Methods Phys. Res. B
376, 393 (2016).
8) S. Takeuchi et al., Nucl. Instrum. Methods Phys. Res.
A763, 596 (2014).

- 35 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Particle identification of light charged particle by SπRIT-TPC in Sn-Sn
isotopic reactions
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(dE/dx)measured − (a × fBethe (β) + b) = 0
∗1
∗2
∗3
∗4
∗5
∗6
∗7

132

Sn+124Sn 270 MeV/u

80000

countsThe nuclear equation of state (EOS) is one of the most
attractive subjects in nuclear physics and astrophysics.
Intermediate energetic heavy ion collisions (HIC) withhigh isospin asymmetry provide us critical knowledge toconstrain the density dependence of the symmetry energy, which contributes to the asymmetric nuclear EOS.
Various types of models have predicted that the spectrum of π − /π + from HIC has a high sensitivity to thesymmetry energy;1,2) however, the lack of experimental
data and the model dependence are still a problem. At
intermediate energies, since the π meson production isdominated by the decay of the ∆ resonance state, whichis excited from the inelastic nucleon-nucleon scattering,
nucleon dynamics in the participant region indirectly inﬂuences the ﬁnal yield of π mesons. Recent progress incalculations based on AMD shows that the cluster correlation alters the nucleon dynamics and has a considerable inﬂuence on the ﬁnal yield of π − /π + as well as thesensitivity of the symmetry energy.3) Therefore, precise
information on the cluster production in HIC is desired.
In order to estimate the relative production rate of lightclusters emitted from Sn-Sn reactions at 270 MeV per
nucleon,4) mass evaluation for the light charged particles is ongoing, which will be described in this report.
The SAMURAI Pion Reconstruction and Ion Tracker
Time Projection Chamber5) was placed into the gap of
the SAMURAI dipole magnet at 0.5 T, which allows us
to measure the energy deposit per unit length (dE/dx)
and the magnetic rigidity of the charged particles individually. In order to calibrate dE/dx and to estimate
the resolution of particle identiﬁcation, the numericalmass is calculated as follows. The mean dE/dx for relativistic charged particles in a material is described wellby the Bethe equation,6) − ⟨dE/dx⟩ = fBethe (β), whereβ is the velocity of the incident particle. Furthermore,
β 2 = (zR)2 /(m2 + (zR)2 ), where z is the charge, and R
and m are the rigidity and mass, respectively. If the experimental locus of dE/dx and the rigidity for a certain
particle species can be ﬁt by g(β) = a × fBethe (β) + b
with ﬁxed z and m (for an example of proton, z = 1 andm = 938.272 ... MeV/c2 ), the empirical dE/dx calculator is obtained. Finally, by solving the equation(1)

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
Department of Physics, Tsinghua University
Lawrence Verkeley National Laboratory, UC Verkeley- 36 -

θ∈ (0°~27°), φ∈ (-40°~40°)
for Z=1 nuclei

60000
40000
20000
0

500

1000

1500

2000

2500

3000

Particle mass (MeV/c2)

3500

4000

Fig. 1. Mass spectrum calculated from dE/dx and rigidity
by using Eq. (1). θ and ϕ are polar and azimuthal angles
in the laboratory frame, respectively.

in terms of mass with z for a certain particle and theobtained coeﬃcients a and b, we can calculate the massfrom the measured dE/dx and rigidity. Figure 1 shows
the mass spectrum calculated by Eq. (1) for a restricted
angle, where the coeﬃcients a and b are obtained byﬁtting the proton locus of dE/dx and rigidity. The protons, deuterons, and tritons are well resolved, but thepeak positions are slightly shifted for deuterons and tritons since only the proton locus is considered for theﬁtting.
In Ref. 6), a highly-skewed Landau distribution is introduced to calculate the energy loss, which considers
the ﬂuctuations of the energy loss during interactions
with a thin absorber material. Investigation on the resolution using Landau formula is also ongoing.
This work is supported by the Japanese MEXT
KAKENHI Grant No. 24105004, the U.S. DOE under Grant Nos. DE-SC0004835, DE-SC0014530, 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 for analyzing the data were provided by
the HOKUSAI system at RIKEN.
References

1) B. A. Li et al., Phys. Rev. C 71, 014608 (2005).
2) M. B. Tsang et al., Phys. Rev. C 95, 044614 (2017).
3) N. Ikeno et al., Phys. Rev. C 97, 069902 (2018).
4) J. Barney et al., RIKEN Accel. Prog. Rep. 50, 49 (2017).
5) R. Shane et al., Nucl. Instrum. Methods Phys. Res. A
784, 513 (2015).
6) http://pdg.lbl.gov/2018/reviews/rpp2018-revpassage-particles-matter.pdf .

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Recent results of collective flow for SπRIT-TPC experiment

∗2
∗3
∗4
∗5
∗6
∗7

∗8

2π/N dN/d( φ - Ψ)

(b)

1.03

(c)

1.15

1.02

1.1

1.01

1.05

1.1

1.05

1

1

1

0.95

0.99

0.95

0.9

0.98

0.9

0.97

0.85

0.85

Since the distribution of Ψ was distorted due to a rectangular shape of SπRIT-TPC, it was corrected applying
a re-centering and a shifting method.6) The azimuthal
angle distributions with respect to Ψ were plotted for
protons measured with 132 Sn + 124 Sn in Fig. 1. In theseplots, Ψ was determined with all light fragments excluding itself to avoid auto correlation. Red lines showsﬁtting results with a formula

∗1

(a)

1.15

2π/N dN/d( φ - Ψ)

The SAMURAI Pion-Reconstruction and Ion-TrackerTime-Projection Chamber (SπRIT-TPC)1) project aims
to constrain a nuclear equation of state (EoS) at suprasaturation density using heavy ion collisions. TheSπRIT-TPC was designed to measure π − /π + production ratio depending on isospin asymmetry. Since thepions are expected to be produced through the ∆ resonance formation, π − /π + ratio is related to some kindof nuetron-to-proton squared ratio which is then supposed to be sensitive to the symmetry energy at highdensities.3)
Additionally, measurements of collective ﬂow with
proton and neutron are proposed as a useful probe2) tonuclear EOS, because neutrons are repelled from dense
region as a result of the repulsive isospin symmetry potential with increase of density, while protons are opposite.
The ﬁrst experiment had been performed in April 2016
with 132 Sn and 108 Sn beams at 270 MeV/nucleon on
112
Sn and 124 Sn targets at SAMURAI in RIBF. Neutrons were detected by NeuLAND4) covering the midrapidity region. In this paper, recent results of the collective ﬂow for proton and neutron will be discussed.
A track reconstruction was done using SπRITROOT
software and particle identiﬁcation ability is discussed
in Ref. 5).
An orientation angle of reaction plane, Ψ was determined with summing up a transverse momentum of lightcharged fragments, p, d, t, 3 He, and 4 He event by event,as following.
(
)
(
) ∑
N
−
→
cos ϕk
Q cos Ψ
(1)
ωk
Q =
=
sin ϕkQ sin Ψk=1{
1 if rapidity in the center of mass > 0ωk =−1 otherwise

2π/N dN/d( φ - Ψ)

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 Collaboration

RIKEN Nishina Center
NSCL and Dept. of Phys. & Ast., Michigan State University
Department of Physics, Korea University
Department of Physics, Kyoto University
IFJ PAN
Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University
Rare Isotope Science Project, Institute for Basic Science
Cyclotron Institute, Texas A&M University- 37 -

0.8
−3

0.8
−2

−1

0

1

2
3
∆ (φ - Ψ)

−3

−2

−1

0

1

2
3
∆ (φ - Ψ)

−3

−2

−1

0

1

2
3
∆ (φ - Ψ)

Fig. 1. Azimuthal angle distributions of proton with respectto Ψ . The rapidity coverages in the center of massare (a) target-rapidity: −4.0 ∼ −0.06, (b) mid-rapidity:−0.06 ∼ 0.06, and (c) Beam-rapidity: 0.06 ∼ 4.0). Redlines indicate fitting with Eq. (2).

2π dN
= 1 + 2v1 cos(ϕ) + 2v2 cos(2ϕ) + ...
N dϕ

(2)

The negative and positive v1 were observed in the target (a) and beam rapidity region (c), which is the evidence of directed ﬂow. The negative v2 was observedin the mid rapidity region (b), which indicates out-ofplane elliptic ﬂow of protons. The strength of v1 and v2
are needed to be corrected with a reaction plane resolution to compare between 132 Sn + 124 Sn and 108 Sn +112
Sn collisions. Neutron’s collective ﬂow was also observed within a limited acceptance. Simulation and further analysis are necessary to extract EoS information.
Addition to neutron to proton ratio, 3 H to 3 He analysis
is ongoing, which is expected to serve in resolving ambiguities caused by the eﬀective-mass splitting between
neutrons and proton.
This work is supported by the U.S. Department of Energy under Grant Nos. DE-SC0004835, DE-SC0014530,
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 UMO-2013/10/M/ST2/00624.
References

1) R. Shane et al., Nucl. Instrum. Methods Phys. Res. A
784, 513 (2015).
2) B. -A. Li et al., Phys. Rev. Lett. 85, 4221 (2000).
3) N. Ikeno et al., Phys. Rev. C 97, 069902 (2018).
4) NeuLAND Technical Design Report, http://www.
fair-center.eu/fileadmin/fair/experiments/NUSTAR/
Pdf/TDRs/NeuLAND-TDR-Web.pdf, accessed: 2016/01/21.
5) M. Kaneko et al., in this report.
6) J. -Y. Ollitrault et al., Nucl. Phys. A 638, 195c (1998).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

New implant-decay correlation method for β-delayed neutron
emission measurements with the BRIKEN setup
O. Hall,∗1 A. Estrade,∗2,∗3 J. Liu,∗4 G. Lorusso,∗3,∗5 K. Matsui,∗3 F. Montes,∗6 N. Nepal,∗2 S. Nishimura,∗3
V. H. Phong,∗3,∗7 J. Agramunt,∗8 D. S. Ahn,∗3 A. Algora,∗8 H. Baba,∗3 S. Bae,∗9 N. T. Brewer,∗10
C. G. Bruno,∗1 R. Cabellero-Folch,∗11 F. Calvino,∗12 T. Davinson,∗1 I. Dillmann,∗11 C. Domingo-Pardo,∗8
S. Go,∗13 C. J. Griﬃn,∗1 R. Grzywacz,∗10,∗13 T. Isobe,∗3 D. Kahl,∗1 G. Kiss,∗3 S. Kubono,∗3 M. Labiche,∗14
A. I. Morales,∗8 B. C. Rasco,∗10 K. P. Rykaczewski,∗10 H. Sakurai,∗3 Y. Shimizu,∗3 T. Sumikama,∗3 H. Suzuki,∗3
H. Takeda,∗3 J. L. Tain,∗8 A. Tarifeno-Saldivia,∗12 A. Tolosa-Delgado,∗8 P. J. Woods,∗1 R. Yokoyama,∗11 for the
BRIKEN collaboration
With the observation of a binary neutron-starmerger accompanied by the spectroscopic identiﬁcation of r -process nucleosynthesis1) taking place in2017, there have been major developments in identifying a site of the r -process. These new observations
will increase the demand for precise nuclear data thatis necessary to reach a clearer understanding of the r process mechanisms thought to be occurring in theseenvironments.
In June 2017, an experiment was performed to study
the decay properties of the β-delayed neutron emittersin the mass region A = 130 near the doubly magic
nucleus 132 Sn. The active-stopper array AIDA2) was
placed at F11 with the nuclei of interest being implanted and detected alongside their subsequent decays in the silicon detector stack. Neutrons emitted
from the β-decay of the implanted ions were detectedby the BRIKEN neutron counter array3,4) surrounding AIDA. The neutron counter array consisted of 140
gas-ﬁlled 3 He counters, which were held inside a large
moderation block made of high-density polyethylene.
In carrying out analysis on the data, a new methodof correlating beta events with implanted ions was developed. As the detectors that comprise the AIDA
detector stack are double-sided silicon strip detectors(DSSDs), positional information of both high energy
implant and low energy decay events is obtained. Withβ-decay energies of 100 s of keV and a narrow strip
pitch of 560 µm, decay events will be spread acrossmultiple strips. This results in a trade-oﬀ between
detection eﬃciency and a background from electronic

Fig. 1. Comparison between the old correlation method (a)and the new method (b). In both images the red circle
indicates an implant particle, the orange circle a beta
particle and the blue circles as noise events.

noise for low energy signals, which is sensitive to thedetection threshold and the correlation method.
In previous experiments single points have been assigned to the location of the implants and betas withcorrelation performed based upon the beta points thatfall within an area around the implant signal, typicallya 7×7 pixel square shown in Fig. 1 a). The new method
instead takes into account all of the strips that ﬁre during an event and assigns an area for both implant anddecay signals. Correlations can then be performed bysearching for an overlap between the areas of the beta
and implant events as shown in Fig. 1 b). This new
method has been shown to reduce the amount of noisecorrelated with implants whilst maintaining the betadetection eﬃciency of the previous method, as noise
events that would otherwise fall within the 7 × 7 area
will now be rejected.
The data analysis for the experiment is ongoing.
The data shows the potential of the BRIKEN setup toextend the systematics of β-delayed neutron emission
probabilities along the N = 82 and Z = 50 shell closures south and east of 132 Sn. The results will improve
the reliability of nuclear data for r -process models.

∗1

School of Physics and Astronomy, University of Edinburgh
College of Science and Engineering, Central Michigan Univeristy∗3 RIKEN Nishina Center∗4 Department of Physics, The University of Hong Kong
∗5 National Physics Laboratory∗6 NSCL and Department of Physics and Astronomy, Michigan
State University∗7 Faculty of Physics,VNU Hanoi University of Science∗8 Instituto de Fı́sica Corpuscular∗9 Department of Physics, Seoul National University∗10 Oak Ridge National Laboratory∗11 TRIUMF∗12 Universitat Politècnica de Catalunya∗13 Department of Physics and Astronomy, University of Tennessee∗14 STFC Daresbury Laboratory∗2

References
1) E. Pian et al., Nature 551, 67–70 (2017).
2) C. J. Griﬃn et al., Proc. XIII Nuclei in the Cosmos 1,
97 (2014).
3) A. Tarifeño-Saldivia et al., J. Instrum. 12, 04006 (2017).
4) B. C. Rasco et al., Nucl. Instrum. Methods Phys. Res.
911, 78–86 (2018).

- 38 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Progress on the measurements of Pn -values and half-lives forunderstanding the formation of the r-process rare-earth peakA. Tarifeño-Saldivia,∗1 G. G. Kiss,∗2 J. L. Tain,∗3 A. Estrade,∗4 J. Agramunt,∗3 T. Davinson,∗5 I. Dillmann,∗10
N. Fukuda,∗6 R. Grzywacz,∗9 O. Hall,∗5 A. I. Morales,∗3 A. Navarro,∗1 N. Nepal,∗4 S. Nishimura,∗6
K. P. Rykaczewski,∗7 N. T Szegedi,∗2 A. Sveiczer,∗2 A. Tolosa-Delgado,∗3 P. Vi,∗8 R. Yokoyama∗9 for the
BRIKEN collaboration∗11
The Rare Earth Peak (REP) is a small, but clearly
distinctive, peak around mass A ∼ 160 in the elemental
solar system abundances created by the rapid neutroncapture process (r-process). In contrast to the r-process
abundance peaks associated with neutron shell closures(e.g. A ∼ 130, 195), which are formed during the(n, γ) ↔ (γ, n) equilibrium, the REP is formed later
after the neutron exhaustion. Thus, the understanding of the REP formation oﬀers a unique probe forthe study of the late times environmental conditionsin the r-process site. According to theoretical models,1) masses, β-decay rates, β-delayed neutron emission
probabilities (Pn ) and the capture rates play a key rolein the formation of the REP. The most inﬂuential nuclei
to the REP formation have been determined by sensitivity studies to be the neutron-rich region with massA ∼ 160 from Cs to Gd.2) The physical input for thesesensitivity studies is based on current nuclear model calculations. Recently, several of the half-lives in the REP
region have been measured by the EURICA collaboration at RIBF in the RIKEN Nishina Center.3) Morerecently, the largest and most eﬃcient β-delayed neutron detector of its kind has been built by the BRIKEN
collaboration,4) at the RIKEN Nishina Center, for asystematic study of the decay properties of the most
exotic neutron-rich nuclei, including the REP nuclei,
accessible currently by experimental means. A detailed
description of the BRIKEN detector and the scientiﬁcprogram of the BRIKEN project is provided by Tain et
al.5)
The NP1612-RIBF148 experiment make use of
BRIKEN for the measurement of β-delayed neutron
emission probabilities and half-lives in the REP nuclei region. The experiment has been allocated with10 days of total beamtime. An exploratory experimental run (2.5 days in total) was carried out in 2017 witha setting centered on 167 Sm, the heaviest most exotic
accessible REP nuclei. This run has provided data for

Fig. 1. Preliminary analysis from partial data for the βdecay for 157 Pr.

measurement of some new half-lives in the region from
Gd to Pm.6) However the statistics for precise measurement of Pn -values was rather poor. In 2018 a newexperimental run has been carried using a total of 5.0
days of beamtime. The 2018 run has used a setting
centered on 165 Pm, providing data for measurement of
Pn -values in the region from Ce to Eu. In Fig. 1 is presented the preliminary analysis of partial data for thecase of 157 Pr. The analysis make use of the approachdeveloped by Tolosa-Delgado et al.7) for a consistent ﬁtof parameters of the decay chain in implant-β-gated andimplant-β-neutron-gated time correlation histograms.
The preliminary analysis yielded a half-live of 327 ms,
in agreement with the previous EURICA measurement(295 ms +10% −4%), and a new Pn -value of 6.8%.
In summary, three quarters of the allocated beamtime for the experiment have been completed. The
coverage region of the experimental data from 2017 and2018 runs, for measurement of the REP Pn -values andhalf-lives, extends from Ce to Gd nuclei. The detailed
data analysis of this region is ongoing.

∗1

Universitat Politècnica de Catalunya (UPC)
Institute for Nuclear Research (Atomki)∗3 Instituto de Fı́sica Corpuscular (IFIC)∗4 University College of Science and Engineering, Central Michigan University (CMU)∗5 School of Physics and Astronomy, University of Edinburgh∗6 RIKEN Nishina Center∗7 Oak Ridge National Laboratory∗8 Faculty of Physics, VNU University of Science∗9 Department of Physics and Astronomy, University of Tennessee∗10 TRIUMF∗11 www.wiki.ed.ac.uk/display/BRIKEN/Home∗2- 39 -

References
1) A. Arcones et al., Phys. Rev. C 83, 045809 (2011).
2) M. R. Mumpower et al., Phys. Rev. C 85, 045801 (2012).
3) J. Wu et al., Phys. Rev. Lett. 118, 072701 (2017).
4) A. Tarifeno-Saldivia et al., J. Instrum. 12, P04006 (2017).
5) J. L. Tain et al., Acta Phys. Pol. B 49, 417–428 (2018).
6) A. Tarifeno-Saldivia et al., RIKEN Accel. Prog. Rep. 51,
55 (2018).
7) A. Tolosa-Delgado et al., Nucl. Instrum. Methods Phys.
Res. A 925, 133–147 (2019).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

β decays of the heaviest N = Z − 1 nuclei and proton instability of
97
In†
J. Park,∗1,∗2 R. Krücken,∗1,∗2 D. Lubos,∗3,∗4,∗5 R. Gernhäuser,∗3 M. Lewitowicz,∗6 S. Nishimura,∗4 and
H. Sakurai∗4,∗7 for the EURICA Collaboration
Table 1. Half-lives, β-decay endpoint energies, log f t values and β-delayed proton emission branching ratios of91
Pd, 95 Cd, 97 In and 99 Sn.

†
∗1
∗2
∗3
∗4
∗5
∗6
∗7

Nucleus
91
Pd
95
Cd
97
In
97m
In
99
Sn

2

T1/2 (ms)
32(3)
32(3)
28(5)
1.3–230 µs
24(4)< 0.63 MeV

0log f t3.4(5)
3.1(5)
3.0(9)bβp (%)
3.0+1.1−0.9
4.5+1.2−1.0
1.7+1.7−0.8

14.7(36)

3.8(7)

3.9+3.4
−1.7

2

97

In

theo
log [T 1/2(s)]1

l = 4 (g9/2)

10230 µs−4

FRDM

In isotopes

HFB

600 ms−2

l = 1 (p 1/2)

(9/2+) ground state

0
AME

−1

DZ

1.3 µs−60.64 MeV

0.5

QEC (MeV)
11.8(22)10.2(17)10.0(30)

S p (MeV)Interesting nuclear structure phenomena can be observed at the limits of neutron or proton binding, providing sensitive probes of shell evolution and/or collective behaviors. Studies have found the doubly magic100
Sn to be stable against proton emission, conﬁrming the robustness of the N, Z = 50 shells. Searches
for even more neutron-deﬁcient nuclei below 100 Sn resulted in a discovery of new isotopes, while also reaching the proton dripline for Rh and Ag isotopes.1)
From a decay spectroscopy experiment at the RIBF,
half-lives, β-decay endpoint energies, and β-delayed
proton emission branching ratios of N = Z − 1 nuclei 91 Pd, 95 Cd, 97 In and 99 Sn were measured with thewide-range active silicon strip stopper array for β andion detection2) (WAS3ABi). The results, summarizedin Table 1, are consistent with β decays of mirror nuclei containing a mixture of Gamow-Teller and Fermi
decay components.
The apparent stability of 97 In against proton emission was investigated. Based on the deﬁcit in the βdecay amplitude of the parent nucleus, an isomericstate in 97 In decaying to 96 Cd via one-proton emission was proposed. Although this decay branch has
not been detected directly, the observation of a γ-ray
transition belonging to the β decay of 96 Cd was a supporting evidence for the proton-emitting isomer. The
missing proton events were hypothesized to have occurred in a time range between the ions’ ﬂight throughthe BigRIPS and ZeroDegree separators (∼600 ns) andthe 600-µs deadtime of WAS3ABi.
From the shell model perspective, 97m In is formedby promoting a π1p1/2 proton into the π0g9/2 orbital,
leaving an unpaired proton in the π1p1/2 orbital andresulting in a spin-parity of (1/2− ). The large spin
diﬀerence and parity change suppress a γ-ray decaybranch to the (9/2+ ) ground state. Experimental halflife limits on the isomer were converted into a hypothetical proton energy range through a theory on proton emission.3) As shown in Fig. 1, the lower angularmomentum barrier for proton emission from the π1p1/2
orbital compared to the π0g9/2 orbital would facilitate
proton emission from the isomer. This result is con-

0.6

0.78 MeV

0.7
0.8
Qp (MeV)

HB

−2

KTUY

95

96

97
A

98

99

Fig. 1. Left: theoretical T1/2 as a function of emitted
proton energy Qp and orbital angular momentum l.
Right: experimental proton separation energy Sp of theground state of 97 In compared with diﬀerent mass predictions.4–9)

sistent with a few mass models which predict 97 In toundergo β decay as opposed to proton emission.
References

Condensed from the article in Phys. Rev. C 97, 051301(R)(2018)
Department of Physics and Astronomy, University of British
Columbia
TRIUMF
Physik Department, Technische Universität München
RIKEN Nishina Center
Excellence Cluster Universe, Technische Universität München
Grand Accélérateur National d’Ions Lourds (GANIL)
Department of Physics, University of Tokyo- 40 -

1) I. Čeliković et al., Phys. Rev. Lett. 116, 162501 (2016).
2) S. Nishimura, Prog. Theor. Exp. Phys. 2012, 03C006(2012).
3) D. S. Delion, R. J. Liotta, R. Wyss, Phys. Rep. 424,
113 (2006).
4) J. Duﬂo, A. P. Zuker, Phys. Rev. C 52, R23 (1995).
5) P. Möller, J. R. Nix, W. D. Myers, W. J. Swiatecki, At.
Data Nucl. Data Tables 59, 185 (1995).
6) S. Goriely, N. Chamel, J. M. Pearson, Phys. Rev. C 88,
061302(R) (2013).
7) H. Koura, T. Tachibana, M. Uno, M. Yamada, Prog.
Theor. Phys. 113, 305 (2005).
8) M. Wang et al., Chin. Phys. C 41, 030003 (2017).
9) H. Herndl, B. A. Brown, Nucl. Phys. A 627, 35 (1997).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Beta-gamma spectroscopy of neutron-rich 150 Ba†
R. Yokoyama,∗1 E. Ideguchi,∗2 G. Simpson,∗3 Mn. Tanaka,∗2 S. Nishimura,∗4 P. Doornenbal,∗4
P. -A. Söderström,∗4 G. Lorusso,∗4 Z. Y. Xu,∗5 J. Wu,∗4,∗6 T. Sumikama,∗7 N. Aoi,∗2 H. Baba,∗4 F. Bello,∗8
F. Browne,∗9,∗4 R. Daido,∗10 Y. Fang,∗10 N. Fukuda,∗4 G. Gey,∗3,∗4,∗11 S. Go,∗1,∗4 N. Inabe,∗4 T. Isobe,∗4
D. Kameda,∗4 K. Kobayashi,∗12 M. Kobayashi,∗1 T. Komatsubara,∗13 T. Kubo,∗4 I. Kuti,∗14 Z. Li,∗6
M. Matsushita,∗1 S. Michimasa,∗1 C. -B. Moon,∗15 H. Nishibata,∗10 I. Nishizuka,∗7 A. Odahara,∗10 Z. Patel,∗16,∗4
S. Rice,∗16,∗4 E. Sahin,∗8 L. Sinclair,∗17,∗4 H. Suzuki,∗4 H. Takeda, ∗4 J. Taprogge,∗18,∗19 Zs. Vajta,∗14
H. Watanabe,∗20 A. Yagi,∗10 and T. Inakura∗21
Intruder orbitals due to the strong l · s coupling inatomic nuclei can cause higher-order interactions, for example, octupole-deformed shapes energetically favoredin certain nuclei. Octupole correlations (λ = 3) arecaused by the interactions between orbits with ∆j =∆l = 3. Nuclei with Z or N = 34, 56, 88, and 134
possess such orbits at or close to the Fermi surface andare expected to have strong octupole correlations. Recently, static octupole deformation was reported in theZ ∼ 88, N ∼ 134 (Ra) region by Gaﬀney et al.2) andat Z ∼ 56, N ∼ 88 (Ba) by Bucher et al.3) However,
the result that 148 Ba may have strong octupole correlation as 144 Ba does4) raised a question whether 150 Ba
also possess strong octupole correlation.
Neutron-rich Ba (Z = 56) isotopes were produced at
RIBF and measured by means of β-γ spectroscopy at theF11 focal plane of the ZeroDegree spectrometer. An active stopper, WAS3ABi,5) and HPGe array, EURICA,6)
were used for β-ion correlation and γ-ray detection, respectively. The γ-ray spectrum of the 150 Cs decay within
0.2 s after implantation is shown in Fig. 1. The estimated continuum background is overlaid. Two peaks at
100 and 597 keV were assigned as transitions in 150 Ba
after a log-likelihood ratio test requiring 4σ signiﬁcance.
From the systematics of 144–148 Ba, the 100-keV and 597+
keV γ rays were assigned as 2+
and 3− → 2+
1 → 0
1
decay, which are also consistent with their intensities.
Condensed from the article in Prog. Theor. Exp. Phys. 2018,
041D02∗1 Center for Nuclear Study, The University of Tokyo∗2 Research Center for Nuclear Physics, Osaka University∗3 LPSC, Université Grenoble-Alpes, CNRS/IN2P3∗4 RIKEN Nishina Center∗5 Department of Physics, The University of Tokyo∗6 Department of Physics, Peking University∗7 Department of Physics, Tohoku University∗8 Department of Physics, University of Oslo
∗9 School of Computing Engineering and Mathematics, University of Brighton∗10 Department of Physics, Osaka University∗11 ILL, Grenoble∗12 Department of Physics, Rikkyo University∗13 Department of Physics, University of Tsukuba∗14 MTA Atomki, Hungarian Academy of Science, Hungary∗15 Department of Display Engineering, Hoseo University∗16 Department of Physics, University of Surrey∗17 Department of Physics, University of York∗18 Instituto de Estructura de la Materia, CSIC
∗19 Departamento de Física Teórica, Universidad Autónoma de
Madrid∗20 Department of Physiscs, Beihang University∗21 Department of Physiscs, Niigata University†- 41 -

Fig. 1. A γ-ray spectrum from the β decay of 150 Cs.

A calculation with the Hartree-Fock method and therandom-phase approximation (RPA) was newly performed.7,8) The calculation predicted that 150 Ba has alarge ground-state octupole deformation, β30 = 0.15, as
those of the even-even A = 144 to 148 isotopes. The
RPA calculation predicted a J = 3 excitation of 150 Ba
at 0.76 MeV, which may be the observed 697 keV state.
The calculated state has B(E3) = 35 W.u., indicatingthat the state is an octupole collective state rather thana single particle one.
In summary, the newly measured E(2+1 ) and possiblyE(3− ) of 150 Ba indicate that the quadrupole deformation of 150 Ba is larger than that of 148 Ba, and there
may exist a negative-parity J = 3 band with a large
octupole collectivity. A newly performed HF-plus-RPA
calculation predicted a static octupole deformation in
the A = 140 to 150 Ba isotopes and excited states withoctupole collectivity at around 1 MeV. The results showthat 150 Ba has a large octupole collectivity and that theregion of octupole correlations around Z = 56, N = 88
may be wider than expected.9,10)
References

1) I. Ahmad et al., Ann. Rev. Nucl. Pt. Sci. 43 71 (1993).
2) L. P. Gaﬀney et al., Nature 497, 199 (2013).
3) B. Bucher et al., Phys. Rev. Lett. 116, 112503 (2016).
4) W. Urban et al., Nucl. Phys. A 613, 107 (1997).
5) S. Nishimura et al., Prog. Theor. Exp. Phys. 2012,
03C006 (2012).
6) P.-A. Söderström et al., Nucl. Instrum. Methods Phys.
Res. B 317, 649 (2013).
7) T. Nakatsukasa et al., Phys. Rev. C 76, 024318 (2007).
8) T. Inakura et al., Phys. Rev. C 80 044301 (2009).
9) P. Möller et al., At. Data Nucl. Data Tables 109, 1(2016).
10) S. E. Agbemava et al., Phys. Rev. C 93, 044304 (2016).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Preliminary results on β-decay of the Tz = −1 nucleus 66 Se at RIBF
P. Aguilera,∗1,∗2 B. Rubio,∗2 F. Molina,∗1 J. Agramunt,∗2 A. Algora,∗2 V. Guadilla,∗2 A. Montaner-Piza,∗2
A. I. Morales,∗2 S. E. A. Orrigo,∗2 B. Blank,∗3 P. Ascher,∗3 M. Gerbaux,∗3 T. Goigoux,∗3 J. Giovinazzo,∗3
S. Grévy,∗3 T. Kurtukian Nieto,∗3 C. Magron,∗3 D. Nishimura,∗4 J. Chiba,∗4 H. Oikawa,∗4 Y. Takei,∗4 S. Yagi,∗4
D. S. Ahn,∗5 P. Doornenbal,∗5 N. Fukuda,∗5 N. Inabe,∗5 G. Kiss,∗5 T. Kubo,∗5 S. Kubono,∗5 S. Nishimura,∗5
Y. Shimizu,∗5 C. Sidong,∗5 P. A. Söderström,∗5 T. Sumikama,∗5 H. Suzuki,∗5 H. Takeda,∗5 V. H. Phong,∗5 J. Wu,∗5
H. Sakurai,∗4,∗5 Y. Fujita,∗6 M. Tanaka,∗6 W. Gelletly,∗2,∗7 F. Diel,∗8 D. Lubos,∗9 G. de Angelis,∗10 D. Napoli,∗10
C. Borcea,∗11 A. Boso,∗12 R. B. Cakirli,∗13 E. Ganioglu,∗13 G. de France,∗14 S. Go,∗15 and K. Wimmer∗16
In this paper, the preliminary results of the analysisof the NP1112-RIBF82 experimental campaign are presented. The main goal of this study is the Tz = −1 66 Se
β-decay.
66
Se was produced using a primary beam of 78 Kr
with 345 MeV/nucleon and a target of Be. The nuclei of interest were separated and identiﬁed at the BigRIPs mass separator by the ΔE-ToF-Bρ method (seeFig. 1 inset). The nuclei of interest were implanted inthree Double-Sided Silicon Strip Detectors (DSSSDs)
named WAS3ABi, surrounded by the EUROBALLRIKEN Cluster Array1) (EURICA).
The β and γ spectra were obtained by the correlations
between implants and decays within a ±400 ms time

window. Backward correlation times were used to subtract random correlations. In Fig. 1, the β spectrumwith background subtraction is shown. A similar procedure was applied to obtain the γ-spectrum, consideringthat EURICA was triggered by WAS3ABi. In Fig. 2 theγ-spectrum is shown.
We present here the ﬁrst experimental results on the
β-delayed gamma decay of 66 Se. Two gamma lines
were previously observed in the isomeric decay2) and inbeam study3) of 66 As. They correspond to the gammadeexcitation of two levels with J π = 1+ and 2+ at
836 keV and 964 keV energy respectively. Throughour analysis, we could identify three additional levels
by implant-γ and implant-γ-γ correlation analysis (seeFig. 3).

Fig. 2. Gamma spectrum following 66 Se decay, backgroundsubtracted. In green, γ lines identiﬁed in 66 Se β-decay.

Fig. 1. Beta spectrum from 66 Se decay with background subtracted and PID selection of 66 Se implants identiﬁed by
the BigRIPs mass separator.

∗1

Chilean Nuclear Energy Commision
IFIC, CSIC-Universidad de Valencia∗3 Centre d’Etudes Nucléaires de Bordeaux-Gradignan∗4 Department of Physics, Tokyo City University∗5 RIKEN Nishina Center∗6 Department of Physics, Osaka University∗7 Department of Physics, Surrey University∗8 Institute of Nuclear Physics, Universität zu Köln
∗9 Physics Department E-12, Technische Universität München∗10 Istituto Nazionale di Fisica Nucleare, Laboratorio Nazionale
di Legnaro∗11 National Institute for Physics and Nuclear Engineering, IFINHH∗12 Istituto Nazionale di Fisica Nucleare, Sezione di Padova∗13 Department of Physics, Istanbul University∗14 Grand Accélérateur National d’Ions Lourds∗15 Department of Physics, Tennessee University∗16 Atomki, Debrecen∗2- 42 -

Fig. 3. (Color online) Preliminary level scheme for 66 Se decay. Levels previously known in the literature are shownin black, blue lines correspond to this work.

References

1) B. Rubio et al., RIKEN Accel. Prog. Rep. 49, 27 (2015).
2) R. Grzywacz et al., Phys. Lett. B 429, 247 (1998).
3) R. Grzywacz et al., Nucl. Phys. A 682, 41c (2001).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Study of β-decay of 71 Kr
A. 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 paper, we present the preliminary results of theanalysis of the experiment NP1112-RIBF93, in particular, the ones related to our study of the β-decay of 71 Kr.
The main objective of the NP1112-RIBF93 experimentis to study p-n pairing and isospin-related features inthe structure of 70, 71 Kr through their β-decays.
71
Kr nuclei were produced in the fragmentation of a78
Kr primary beam with an energy of 345 MeV/nucleon.
The high intensity beam provided by the accelerator
complex of the RI Beam Factory (RIBF) enabled us toachive primary beam currents around 40 pnA. The primary beam impinged on a 5 mm thick Be target to produce a cocktail beam. After the separation and selectionin the BigRIPS separator (see Fig. 1), the nuclei were
implanted in the WAS3ABi active stopper, surroundedby the EURICA γ-ray spectrometer.1)
Standard β-γ and β-γ-γ coincidence techniques wereapplied to study the β-decay of 71 Kr. New γ transitions have been identiﬁed based on the comparisons between the half-lives obtained from implant-β-γ correlations and the half-life values determined from the corresponding correlations of previously identiﬁed γ-rays
that belong to the 71 Kr decay (198, 207 and 397-keVtransitions). In total, 4 new γ transitions have been
identiﬁed. After the identiﬁcation of all γ-rays that belong to this decay, γ-γ coincidences were also studied.
A new half-life value was determined using the implantβ-γ time correlations with coincidence conditions on thestrongest identiﬁed γ-rays of the decay. Several factors∗1

IFIC, CSIC-Univ. Valencia∗2 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, Université Paris-Saclay∗17 GANIL-Caen∗18 Department of Physics, York University∗19 Department of Physics, University of Hong Kong
∗20 GSI

Fig. 1. Identification plot for the isotopes produced in 78 Kr
fragmentation for the 71 Kr setting.

Fig. 2. Half-life of 71 Kr determined in this work.

that can inﬂuence the quality of the ﬁt and the ﬁnal
value were taken into account as in our previous 70 Br
study.2) Figure 2 shows the half-life of the 71 Kr decay obtained with this method. The half-life obtained of T1/2
= 96.55(79) ms for this decay was signiﬁcantly consistent
with the previous measurements and it is the most precise value reported until now in the literature. Presently,
a new decay scheme is being constructed. The analysesof the 70, 71 Kr β and the possible 71 Kr isomer decays arestill in progress.
References

1) S. Nishimura, Prog. Theor. Exp. Phys. 03C006 (2012).
2) A. I. Morales et al., Phys. Rev. C 95, 064327 (2017).

- 43 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Coexisting single-particle and octupole states in 133 Sn
G. Simpson,∗1 J. Keatings,∗2 A. Jungclaus,∗3 J. Taprogge,∗4 S. Nishimura,∗5 P. Doornenbal,∗5 G. Lorusso,∗5
P. -A. Söderström,∗5 T. Sumikama,∗5 J. Wu,∗5 Z. Y. Xu,∗5 T. Isobe,∗5 H. Sakurai,∗5 andthe EURICA RIBF-85 collaboration∗5
200

∗1
∗2
∗3
∗4
∗5

375 *

γ-rays emitted fromparent nuclei

1500

2000 2500 3000
Energy (keV)

35004041 *

1000

1561 +
1779 +
0
0

In

4000

4351 *

500

50

4041 single escape *3562 +

neutrons
neutrons

299 *

100

133

+ β decay* β-n decay

511

Counts per keV

1504041 double escape *The experimental study of single valence particle(hole) nuclei provides crucial experimental data for nuclear structure studies. In particular the energies of
low-lying levels in these nuclei can provide the eﬀective single-particle (hole) energies used in shell-model
calculations.1) In experiment RIBF-85,1,2) , which waspart of the EURICA campaign, the single valence neutron nucleus 133 Sn was studied following the β- andβ-n decay of 133, 134 In parent nuclei. This has allowed the energies of several single-particle states tobe veriﬁed and the γ decays of new levels observed.
To date all single-particle states in the N = 82–126
valence shell have been directly experimentally identiﬁed in 133 Sn, except the νi13/2 one.3–5) Furthermore
the recent report of enhanced quadrupole and octupole
strength in 132 Sn6) allows searches for more complex
states to be performed. The co-existence of spherical single-particle and collective states appears to be aubiquitous feature of the nuclear landscape.
The high Qβ and Qβ−n values of 14135(60) keV and
11110(270) keV for the β and β-n decays of 133, 134 In,
respectively, make them ideal for studying a wide rangeof states in 133 Sn. The diﬀering spins of the groundstates of these nuclei [(9/2+ ) and (4− −7− )] mean thatlevels with diﬀerent spin ranges should be populated.
The experimental γ-ray spectrum obtained following the decay of selected and implanted 133 In ions ispresented in Fig. 1. Many transitions previously assigned to 132 Sn are observed.7) A new γ decay of energy 1779 keV is assigned to 133 Sn as this transition
was observed following both the β decay of 133 In andthe β-n decay of 134 In. The 1561-keV transition, previously reported in several experiments is conﬁrmed.3–5)
However, no evidence was found for the 513- and 854keV γ decays of the νp3/2 and νp1/2 states from parent
133
In nuclei.4) This shows that 133 In was much more
−1ground state, than thestrongly populated in its πg9/2−1
πp1/2 long-lived isomer. The γ decay of the 854-keV
νp3/2 state was however observed following the β-n decay of 134 In.
The 1561-keV transition receives more than one
third of the total feeding intensity following the β-ndecay of 134 In. The weak population of the 1779-keV
state in 133 Sn following β-n decay means that it may
have a positive parity.

4500

Fig. 1. γ-ray spectrum obtained from the β-decay of 133 In
in the current work.

Octupole excitations are amongst the ﬁrst few excited states in 132 Sn7) and have recently been shown
to possess enhanced collectivity.6) As the 1779-keV
state has not been populated in transfer reaction experiments then its isospin quantum number is probably diﬀerent to that of the neighboring states4,5,8) The
1⊗3− conﬁguration
1779-keV state probably has a νf7/2
and is lowered in energy due to an attractive protonneutron interaction.
Following the β decay of 133 In the log f t value forthe 1779-keV state was measured to be 6.9(1). This iscompatible with either a ﬁrst-forbidden transition or ahindered allowed Fermi one. Here the hindrance occurs
due to ΔT �= 0 between the initial and ﬁnal states,
which impedes Fermi transitions. This underlines thecomplex nature of the octupole state, which contains
multiple particle-hole excitations.
Evidence of coexisting single-particle and octupole
states at an energy of ∼1.6 MeV in 133 Sn is presented.
It is a theoretical challenge to reproduce these states.
References
1) J. Taprogge et al., Phys. Rev. Lett. 112, 132501 (2014).
2) G. Simpson et al., Phys. Rev. Lett. 113, 132502 (2014).
3) P. Hoﬀ et al., Phys. Rev. Lett. 77, 1020 (1996).
4) J. M. Allmond et al., Phys. Rev. Lett. 112, 172701(2014).
5) V. Vaquero et al., Phys. Rev. Lett. 118, 202505 (2017).
6) D. Rosiak et al., Phys. Rev. Lett. 121, 252501 (2018).
7) B. Fogelberg et al., Phys. Rev. Lett. 73, 2413 (1994).
8) K. Jones et al., Phys. Rev. C 84, 034601 (2011).

LPSC, Grenoble
School of Engineering, University of the West of Scotland
IEM, CSIC Madrid
Departamento de Fı́sica Téorica,Universidad Autonoma de
MadridRIKEN Nishina Center- 44 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Inelastic scattering of neutron-rich Ni and Zn
isotopes oﬀ a proton target†
M. L. Cortés,∗1,∗2 P. Doornenbal,∗3 M. Dupuis,∗4 S. M. Lenzi,∗5 F. Nowacki,∗6 A. Obertelli,∗7,∗3 S. Péru,∗4
N. Pietralla,∗1 V. Werner,∗1 K. Wimmer,∗8 and the NP1312-RIBF118 collaboration.
One of the most important insight on nuclear structure obtained from studies performed at radioactive ion
beam facilities is the modiﬁcation of the shell closureswith varying number of protons and neutrons.1) Thisshell-evolution has been widely studied, in particularon the neutron-rich side of the nuclear chart. Experimental evidence suggests, for example, the appearanceof new magic numbers at N = 32, 34 in Ca isotopes,2,3)
as well as the disappearance of the shell closures at
N = 8, 20 and 281) in various neutron-rich isotopes.
For the Ni isotopic chain, the reduced transition probability, B(E2)↑, measured between N = 28 and N = 40,
shows a parabolic trend which indicates a subshell closure at N = 40. A measurement of the B(E2)↑ value of70
Ni indicated an enhanced collectivity for N = 42,4)
thus a possible weakening of the Z = 28 gap towards
78
Ni. In contrast, measurements of 72, 74 Ni5,6) show a
reduced B(E2)↑ value for these isotopes, corroborating
the magic character of the N = 50 and Z = 28 shellgaps.
In the experiment, performed at the RIBF as partof the ﬁrst SEASTAR campaign, a 238 U primary beamwith an energy of 345 MeV/nucleon and an averageintensity of 12 pnA impinged on a 3 mm thick 9 Be target at the entrance of BigRIPS.7) After selection andidentiﬁcation, 72, 74 Ni and 76, 80 Zn ions were focused on
the MINOS device,8) composed of a 102(1) mm longliquid hydrogen target surrounded by a Time Projection Chamber (TPC). Due to the low eﬃciency of MINOS for the (p, p′ ) reaction, the information of the TPC
was not used, leading to a decrease of the resolution of
1 MeV γ-rays from a typical 9% using MINOS, to 14%.
Reaction products were identiﬁed using the ZeroDegree spectrometer,7) and γ rays were detected with the
DALI2 array,9) composed of 186 NaI(Tl) detectors. The
full-energy-peak eﬃciency of the array was determinedusing a detailed Geant4 simulation and was found to
be 14% at 1.33 MeV with an energy resolution of 6.2%
(FWHM) for a stationary source.
Direct proton inelastic scattering cross sections to the+2+
1 and 41 states were inferred from the γ-ray spectrum of each isotope. Such cross sections were analyzed
considering two reaction models. First, a microscopic
†

∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

Condensed from the article in Phys. Rev. C 97, 044315 (2018)
Institut für Kernphysik, Technische Universität Darmstadt
GSI Helmoltzzentrum für Schwerionenforschung GmbHRIKEN Nishina Center
CEA, DAM, DIF
Dipartimento di Fisica e Astronomia, Universitá di Padova
IPHC, CNRS/IN2P3, Université de Strasbourg
IRFU, CEA, Université Paris-Saclay
Department of Physics, University of Tokyo- 45 -

approach, based on transition densities obtained from
Quasiparticle Random Phase Approximation (QRPA)
and the Jeukenne-Lejeune-Mahaux (JLM) potential,10)
was used to calculate theoretical inelastic scatteringcross sections. To deal with the high energies of thebeam in front of the target (≈ 270 MeV), an extensionof the JLM folding model above 200 MeV/nucleon wasdeveloped. This approach provided the theoreticalcross sections for inelastic scattering to the 2+
1 stateof 72, 74 Ni and 80 Zn. By comparing the theoretical andexperimental cross sections, neutron-to-proton matrix
element ratios, Mn /Mp , were obtained. The results
suggest that for the Ni isotopes (Mn /Mp ) > (N/Z),
which implies that the contribution of the neutrons tothe collectivity is enhanced. For 80 Zn, the calculation
yields (Mn /Mp ) < (N/Z), which is in agreement withan increased role of the protons to the collectivity. Second, deformation lengths for the ﬁrst quadrupole excitation of each isotope were obtained using the ECIS9711) code. The calculations included a collective vibrational model and used the KD02 global optical potential.12) From the deformation lengths a matter deformation parameter β2 (p, p′ ) was obtained and compared with previously measured charge deformations,
β2 (EM). For the Ni isotopes β2 (p, p′ ) is slightly higher
than β2 (EM), consistent with a previous measurementon 74 Ni13) and with the conservation of the Z = 28 gap
for neutron-rich Ni isotopes. The opposite eﬀect is observed for 80 Zn, thus suggesting that the shell closure
for N = 50 is conserved when approaching Z = 28.
This work represents a step towards a consistent interpretation of the (p, p′ ) data and will be beneﬁcial forthe extraction of useful physics parameters linked tonuclear structure calculations.
References
1) O. Sorlin et al., Prog. Part. Nucl. Phys. 61, 602 (2008).
2) F. Wienholtz et al., Nature 498, 346 (2013).
3) D. Steppenbeck et al., Nature 502, 207 (2013).
4) O. Perru et al., Phys. Rev. Lett. 96, 232501 (2006).
5) K. Kolos et al., Phys. Rev. Lett. 116, 122502 (2016).
6) T. Marchi et al., Phys. Rev. Lett. 113, 182501 (2014).
7) T. Kubo et al., Prog. Theor. Exp. Phys. 2012 (2012).
8) A. Obertelli et al., Eur. Phys. J. A 50, 8 (2014).
9) S. Takeuchi et al., Nucl. Instrum. Methods Phys. Res.
A 763, 596 (2014).
10) J.-P. Jeukenne et al., Phys. Rev. C 16, 80 (1977).
11) J. Raynal, Phys. Rev. C 23, 2571 (1981).
12) A. Koning et al., Nucl. Phys. A 713, 231 (2003).
13) N. Aoi et al., Phys. Lett. B 692, 302 (2010).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Magnetic-moment measurement of the isomeric state of 130 Sn
in the vicinity of 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 A. Kusoglu,∗8 W. Kobayashi,∗4 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 C. Sotty,∗9 A. Stuchbery,∗3 T. Sumikama,∗1
H. Suzuki,∗1 M. Tajima,∗1 A. Takamine,∗1 Y. Takeuchi,∗4 H. Takeda,∗1 A. Toda,∗5 A. Turturica,∗9 H. Ueno,∗1
and H. Yamazaki∗1in thickness and 30 × 30 mm2 in area. The dipole magnet provided a static magnetic ﬁeld of B0 = 0.150 T.
130m
Sn was implanted into the Cu stopper and γ rays
were detected with four Ge detectors located in a plane
perpendicular to B0 at a distance of 7.0 cm from thestopper and at every 90 degrees. Two LaBr3 detectors were also placed at 90 degrees with respect toeach other so as not to interfere with the Ge detectors.
The plastic scintillator with a thickness of 0.1 mm wasplaced upstream of the stopper. Its signal provided thetime-zero trigger. The TDPAD apparatus enabled us
to determine the g-factor of 130m Sn by observing thechanges in anisotropy of the de-excitation γ rays emitted from spin-aligned 130m Sn in synchronization withthe spin precession in the presence of an external ﬁeld.
In this experiment, we observed two cascade γ raysfrom 130 Sn with energies of 97 keV and 391 keV. The
R(t) ratio representing the change in the anisotropy ofγ rays was obtained according to

The 130 Sn nucleus is located in the vicinity of the
doubly-magic nucleus 132 Sn and known to have an isomeric state at an energy level of 2435 keV with a halflife of 1.61 µs.1–3) Its spin parity has been tentatively
assigned to be 10+ where a conﬁguration of two neutron holes coupled in parallel in the h11/2 orbital is
expected to be predominated. The purity of the conﬁguration can be a good indicator of the magicity near132
Sn. Therefore, we measured the magnetic momentof the isomeric state of 130 Sn.
The experiment was conducted at the BigRIPS at
the RIBF. The two-step fragmentation scheme4) was
employed to produce spin-aligned 130 Sn beam. In thereaction at F0, 132 Sn was produced by a ﬁssion reaction of a 345-MeV/nucleon 238 U beam on a 9 Be target
with a thickness of 6 mm. A wedge-shaped aluminium
degrader with a mean thickness of 6 mm was placed at
the ﬁrst momentum-dispersive focal plane F1, where
the momentum acceptance at F1 was ±1.4%. The secondary 132 Sn beam was introduced to a second target
of wedge-shaped aluminum with a mean thickness of
2 mm, placed at the momentum-dispersive focal plane
F5. The 130 Sn nuclei including those in the isomericstate 130m Sn, were produced by removing two neutrons
from 132 Sn. The 130 Sn beam was subsequently transported to F7 under the condition that the momentum
dispersion between F5 and F7 was matched to thatbetween F3 and F5. The slit width at F7 was set to±9 mm. The intensity and purity of 130 Sn in the tertiary beam were 30 cps and 30%, respectively.
The 130 Sn beam was introduced to the experimental
apparatus for time-diﬀerential perturbed angular distribution (TDPAD) measurement, which was placed at
the focal plane F12. The TDPAD apparatus consistedof a dipole magnet, a Cu crystal stopper, Ge detectors,
and a plastic scintillator. The Cu stopper was 3.0 mm

R(t) =

N13 (t) − ϵN24 (t),N13 (t) + ϵN24 (t)(1)

where N13 (t) and N24 (t) are the aggregates of thephoto-peak count rates in the two pairs of Ge detectors
placed diagonally to each other, and ϵ denotes a correction factor for the diﬀerence in detection eﬃciency.
The same applies to the LaBr3 detectors. Theoretically, R(t) is expressed as a function of t as,
R(t) =

3A22
cos 2(ωL t + α),
4 + A22(2)

in terms of the rank-two anisotropy parameter A22 =AB2 F2 , where A denotes the degree of spin alignment,
B2 is the statistical tensor for complete alignment, andF2 is the radiation parameter. The Larmor frequency
ωL is given by ωL = gµN B0 /h̄, where g is the g-factorof 130m Sn in the unit of nuclear magneton µN . α is theinitial phase of the precession depending on the detector arrangement. The detailed analysis and deductionof the g-factor are in progress.

∗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 Department of Physics, Istanbul University∗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).

- 46 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Track distortion due to ion back flow in CAT-S at RIBF113:
132
Sn(d, d’) measurement

The equation of state (EoS) of nuclear matter not
only governs the femto-scale quantum many-body system, namely nuclei, but also plays an important rolein the structure of neutron stars and in supernova phenomena. In particular, the EoS of isospin asymmetricnuclear matter has attracted much interest from theviewpoint of the existence of heavy neutron stars. Although the asymmetric term of incompressibility, Kτ ,can be a benchmark for various EoSs thanks to thedirect accessibility via the measurements of isoscalar
giant monopole resonances,1) the ambiguity of the Kτ
is still larger than those of other EoS parameters. The
measurement of deuterium inelastic scattering oﬀ 132 Sn
was performed at RIBF in RIKEN, aiming at a more
precise determination of the Kτ value.
An active target CAT-S has been employed for themeasurement2) to measure the forward angle scattering,which is sensitive to the monopole transition, together
with the backward angle scattering. A cocktail beamof 132 Sn, 133 Sb, and 134 Te having the total intensity of
3.2 × 105 particles per second bombarded the CAT-S
ﬁlled with 0.4-atm pure deuterium gas. A set of three
400-µm thick THGEMs is used for the electron multiplication device in TPC of CAT-S. In this paper, we
report the observed ﬁeld distortion due to the injectionof the high-intensity heavy-ion beam and its treatmentin the tracking procedure.
There is a phenomena called ion back ﬂow (IBF)where the ions produced in the THGEMs go back to
the drift region through the hole of the THGEMs. The
drift velocity of the ion is as slow as 0.01 cm/µs anda signiﬁcant number of ions exists along the beam axis
like a wall if the IBF rate is large. Since the geometrical conﬁguration and voltage settings of THGEMs in
RIBF113 were not optimized for the reduction of the
IBF rate, the eﬀect of space charge due to the ions is

Vertex along beam axis (mm)S. Ota,∗1 H. Tokieda,∗1 C. Iwamoto,∗1 M. Dozono,∗1 U. Garg,∗2 S. Hayakawa,∗1 K. Kawata,∗1 N. Kitamura,∗1
M. Kobayashi,∗1 S. Masuoka,∗1 S. Michimasa,∗1 A. Obertelli,∗3,∗4 D. Suzuki,∗4 R. Yokoyama,∗1 J. Zenihiro,∗4
R. Kojima,∗1 H. Baba,∗4 O. Beliuskina,∗1 S. Chebotaryov,∗4 P. Egelhof,∗5 T. Harada,∗6 M. N. Harakeh,∗7
K. Howard,∗2 N. Imai,∗1 M. Itoh,∗8 Y. Kiyokawa,∗1 C. S. Lee,∗1 Y. Maeda,∗9 Y. Matsuda,∗8 E. Milman,∗4
V. Panin,∗4 H. Sakaguchi,∗10 P. Schrock,∗1 S. Shimoura,∗1 L. Stuhl,∗4 M. Takaki,∗1 K. Taniue,∗9 S. Terashima,∗11
T. Uesaka,∗4 Y. N. Watanabe,∗12 K. Wimmer,∗1,∗4,∗12 K. Yako,∗1 Y. Yamaguchi,∗1 Z. Yang,∗4 and K. Yoneda∗4
50

10

0

10 1
10−11

-50
-10

∗1

Center for Nuclear Study, the University of Tokyo
Department of Physics, University of Notre Dame
∗3 Le Centre CEA de Saclay∗4 RIKEN Nishina Center∗5 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗6 Department of Physics, Toho University∗7 KVI, Center for Advanced Radiation Technology∗8 Cyclotron and Radio Isotope Center, Tohoku University∗9 Department of Applied Physics, University of Miyazaki∗10 Research Center for Nuclear Physics, Osaka University∗11 Dept. of Nucl. Sci. and Tech., Beihang University∗12 Department of Physics, the Univerisity of Tokyo
∗2

1

0

10 -10

Excitation Energy (MeV)

0

10

Excitation Energy (MeV)

Fig. 1. Corrected (left) and uncorrected (right) correlation.

observed. This eﬀect on the trajectory of recoil particle is observed in the vertex position dependence of theexcitation energy (shown in the right panel of Fig. 1).
because the position displacement along the beam axischanges the angle of trajectory. A locus around theexcitation energy of zero corresponds to elastic scattering. Large deviations at the entrance (Z = −50) andexit (Z = 50) are clearly seen. The ﬁeld distortion isestimated by using the ﬁnite element solver (FEniCS
project) assuming a certain ion density along the beamaxis in the active volume. The resultant position displacement between the electron generated point and theobserved point are estimated by the simulation of electron transportation taking the estimated ﬁeld distortion
into account. Left panel of Fig. 1 shows the result withtaking the position displacement into account in tracking procedure. In this procedure, the IBF rate of 32%
is assumed. Now the locus of elastic scattering becomesstraight and the eﬀect of the IBF is compensated. The
best estimator of the IBF rate can be obtained by comparing the widths of elastic peaks assuming various IBF
rates.
The excitation energy with beam particle identiﬁcation is obtained and signiﬁcant statistics is observed in
the GMR energy region in excitation energy spectrumof each isotope. The analysis to ﬁnalize the excitationenergy spectra at forward angle is ongoing and the further analysis for backward angle will be performed.
References

1) T. Li et al., Phys. Rev. Lett. 99, 162503 (2007).
2) S. Ota et al., J. Radioanal. Nucl. Chem. 305, 907–911(2015).

- 47 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

First mass measurements of neutron-rich calcium isotopes, 55–57 Ca†
S. Michimasa,∗1 M. Kobayashi,∗1 Y. Kiyokawa,∗1 S. Ota,∗1 D. S. Ahn,∗2 H. Baba,∗2 G. P. A. Berg,∗3
M. Dozono,∗1 N. Fukuda,∗2 T. Furuno,∗4 E. Ideguchi,∗5 N. Inabe,∗2 T. Kawabata,∗4 S. Kawase,∗6 K. Kisamori,∗1
K. Kobayashi,∗7 T. Kubo,∗8,∗9 Y. Kubota,∗2 C. S. Lee,∗1 M. Matsushita,∗1 H. Miya,∗1 A. Mizukami,∗10
H. Nagakura,∗7 D. Nishimura,∗11 H. Oikawa,∗10 H. Sakai,∗2 Y. Shimizu,∗2 A. Stolz,∗9 H. Suzuki,∗2 M. Takaki,∗1
H. Takeda,∗2 S. Takeuchi,∗12 H. Tokieda,∗1 T. Uesaka,∗2 K. Yako,∗1 Y. Yamaguchi,∗1 Y. Yanagisawa,∗2
R. Yokoyama,∗13 K. Yoshida,∗2 and S. Shimoura∗1
The mass of atomic nuclei is a fundamental quantity
as it reflects the sum of all interactions within the nucleus, which is a quantum many-body system comprisedof two kinds of fermions, protons and neutrons. Changes
in the shell structures in nuclei far from stability can bedirectly probed by mass measurements.
The shell evolution of the neutron 2p1/2 and 1f5/2 orbitals in neutron-rich calcium region has attracted considerable attention in recent years. The presence of alarge subshell gap at N = 34 between the orbitals in
the Ca isotopes was theoretically predicted,1) and the54
Ca suggested the possible
measurement of E(2+1 ) inemergence of a sizable subshell closure at N = 34.2)
One of the most critical information on the existence ofthe subshell gap at N = 34 is the atomic masses of thecalcium isotopes beyond N = 34. We performed the firstmass measurements of neutron-rich Ca isotopes beyond
N = 34 to probe the shell evolution of the neutron 2p1/2
and 1f5/2 orbitals.
The experiment was performed at the Radioactive Isotope Beam Factory (RIBF) at RIKEN, which is operated by RIKEN Nishina Center and Center for Nuclear
Study, University of Tokyo. The masses were measured
directly by using the TOF–Bρ technique. Neutron-richisotopes were produced by fragmentation of a 70 Zn primary beam at 345 MeV/nucleon in a 9 Be target. The
fragments were separated by the BigRIPS separator,3)
and transported in the High-Resolution Beam Line to
the SHARAQ spectrometer.4) Details on the experimental setup and analysis procedure can be found in theprevious report.5)
We discussed the evolution of the empirical δe shell
gaps6) of neutron-rich Ca isotopes from the atomic
masses of 55–57 Ca, as shown in Fig. 1. The δe value
is identical with S2n (N ) − S2n (N + 1), where S2n (N )is the two-neutron separation energy of a nucleus with
Condensed from the article in Phys. Rev. Lett. 121, 022506(2018)∗1 Center for Nuclear Study, The University of Tokyo∗2 RIKEN Nishina Center∗3 Dept. of Physics, University of Notre Dame, USA∗4 Dept. of Physics, Kyoto University∗5 RCNP, Osaka University∗6 Dept. of Advanced Energy Engineering Sciences, Kyushu University∗7 Dept. of Physics, Rikkyo University∗8 FRIB, MSU, USA∗9 NSCL, MSU, USA∗10 Dept. of Physics, Tokyo University of Science∗11 Dept. of Physics, Tokyo City University∗12 Dept. of Physics, Tokyo Institute of Technology∗13 Dept. of Physics & Astronomy, University of Tennessee†- 48 -

Fig. 1. The empirical δe shell gaps in neutron-rich Ca isotopes. Squares indicate values determined for the firsttime, and circles are literature values from AME2016.7)
The solid lines show theoretical predictions.8–11)

neutron number N, and the empirical energy gaps acrossthe Fermi surface in the nuclei is evaluated. In the
figure, the squares represent the experimental δe values determined for the first time, while the circles represent the literature values obtained from AME2016.7)
The solid lines indicate the theoretical predictions by using KB3G,8) MBPT,9) IM-SRG,10) and modified SDPFMU (SDPF-BR)11) interactions. The empirical energy
gap at N = 34 is close to that at N = 32, and slightly
smaller than that at N = 28. Thus, the experimental
result indicates a sizable energy gap of subshells in 54 Ca,
which is comparable to that in 52 Ca. However the gap
is not as large as recent predictions by SDPF-BR and
IM-SRG interactions. We are preparing a physics article
to report the shell evolution in neutron-rich Ca isotopes
beyond N = 34.
References

1) T. Otsuka et al., Phys. Rev. Lett. 87, 082502 (2001).
2) D. Steppenbeck et al., Nature 502, 207 (2013).
3) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
4) T. Uesaka et al., Prog. Theor. Exp. Phys. 2012, 03C007(2012).
5) M. Kobayashi et al., RIKEN Accel. Prog. Rep. 50, 59(2017).
6) W. Satuła, et al., Phys. Rev. Lett. 81, 3599 (1998).
7) M. Wang et al., Chin. Phys. C 41, 030003 (2017).
8) A. Poves et al., Nucl. Phys. A 694, 157 (2001).
9) J. D. Holt et al., Phys. Rev. C 90, 024312 (2014).
10) J. Simonis et al., Phys. Rev. C 96, 014303 (2017).
11) Y. Utsuno et al., Phys. Rev. C 86, 051301 (2012).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Re-measurement of the 4 He(8 He, 8 Be) reaction

∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

100
90
80

(a)

70
60
50
40
30
20
10
0
0

Counts (a.u.)

In our previous study, the candidate resonanceof 4n system (tetra-neutron) was found using the4
He(8 He, 8 Be)4n reaction with a 186 MeV/nucleon 8 He
beam.1) A new measurement with better statistics andbetter accuracy was performed to evidence the existence of the tetra-neutron system.2)
The intensity of the 8 He beam (3.5×106 particles per
second at the liquid helium target) was approximately
twice compared to that of the previous experiment.
A pair of cathode readout drift chambers (CRDCs)
was used at the ﬁnal focal plane of the SHARAQ spectrometer. To improve the resolution, the positions andangles of the CRDCs were precisely calibrated in thesoftware analysis by using the reference data of a 4 He
beam. We achieved position resolutions of 0.40 and
0.62 mm FWHM and angular resolutions of 1.12 and1.87 mrad FWHM in the horizontal and vertical directions, respectively. Ion optical analysis was then performed to evaluate the ion transport matrix elementsof both the beam line and the SHARAQ spectrometer. The scattering angle of the reaction was deduced
from the angle measured by the CRDCs after taking
the ion transport matrix into account. Higher orderaberrations were thus corrected for. We obtained aresolution of 4.7 and 2.8 mrad FWHM in the horizontal and vertical directions, respectively.
In the previous experiment, the systematic uncertainty was 1.25 MeV mostly due to the fact that noreference data were measured in the momentum regionof the tetra-neutron resonance. In this experiment,
we measured the 1 H(3 H, 3 He)n reaction by using a 3 H
beam at 310 MeV/nucleon (8.3 Tm) and a CH2 target.
The advantage of this reaction is that the rigidity ofboth the beam and the ejectile are the same as thatof the 4 He(8 He, 8 Be)4n reaction at 186 MeV/nucleon.
Therefore, the reaction of reference and the reactionof physics can be measured in the same momentum
window without changing the magnet settings.
Figure 1 (a) shows the kinematical curve of the1
H(3 H, 3 He) reaction. The scattering angle is plotted

Scattering angle (mrad)

S. Masuoka,∗1 S. Shimoura,∗1 M. Takaki,∗1 S. Ota,∗1 S. Michimasa,∗1 M. Dozono,∗1 C. Iwamoto,∗1
K. Kawata,∗1 N. Kitamura,∗1 M. Kobayashi,∗1 R. Nakajima,∗1 H. Tokieda,∗1 R. Yokoyama,∗1 D. S. Ahn,∗2
H. Baba,∗2 N. Fukuda,∗2 T. Harada,∗3 E. Ideguchi,∗4 N. Imai,∗1 N. Inabe,∗2 Y. Kondo,∗5 T. Kubo,∗2
Y. Maeda,∗6 F. M. Marqués,∗7 M. Matsushita,∗1 T. Nakamura,∗5 N. Orr,∗7 H. Sakai,∗2 H. Sato,∗2 P. Schrock,∗1
L. Stuhl,∗1,∗2 T. Sumikama,∗2 H. Suzuki,∗2 H. Takeda,∗2 K. Taniue,∗6 T. Uesaka,∗2 K. Wimmer,∗8 K. Yako,∗1
Y. Yamaguchi,∗1 Y. Yanagisawa,∗2 K. Yoshida,∗2 and J. Zenihiro∗2

350
300

0.2

0.4

0.6

0.8

1

1.2

1.4
1.6
1.8
2
Missing momentum (%)

0.4

0.6

0.8

1

1.2

1.4
1.6
1.8
2
Missing momentum (%)

(b)

250
200
150
100
50
0
0

0.2

Fig. 1. (a) Plot of the scattering angle against the missing
momentum. The kinematical curve of 1 H(3 H, 3 He)n reaction is visible. (b) Missing momentum spectrum after
correcting for the scattering angle in (a).

against the missing momentum, which is given by the
momentum diﬀerence between the 3 H beam and the3
He ejectile. Figure 1 (b) shows the spectrum of themissing mass momenta after correcting for the scattering angle dependence. Given the known Q-value of the1
H(3 H, 3 He) reaction, the missing mass momentum of
the peak seen in the ﬁgure was taken as a reference.
The uncertainty of the excitation energy of 4n is evaluated to be 26 keV RMS due to the uncertainty of thepeak position in Fig. 1 (b).
Further analysis is ongoing.
References

Center for Nuclear Study, the University of Tokyo
RIKEN Nishina Center
Department of Physics, Toho University
Research Center for Nuclear Physics, Osaka University
Department of Physics, Tokyo Institute of Technology
Faculty of Engineering, University of Miyazaki
Laboratorie de Physique Corpusculaire, IN2P3-CNRS, ENSICAEN et Université de Caen
Department of Physics, the University of Tokyo

1) K. Kisamori et al., Phys. Rev. Lett. 116, 052501 (2016).
2) S. Masuoka et al., RIKEN Accel. Prog. Rep. 50, 198(2017).

- 49 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Evaluation of 79 Se(n, γ)80 Se reaction by measuring 77, 79 Se(d, p)78, 80 Se
reactions

The ﬁrst excited state at 95.7 keV in 79 Se, which is located on the path of the s-process nucleosynthesis, has atiny branch of β decay to 79 Br. Depending on the temperature of the astrophysical site, some ground states of
79
Se can be excited to produce 79 Br. The ratio of 80 Se
to 79 Se in a meteorite indicates the temperature of thesite.1) However, the neutron capture reaction on 79 Se
which is the main reaction ﬂow in the s-process has notbeen measured.
The nucleus is known as one of the long-lived ﬁssion
products (LLFP) of nuclear waste. To design the facility to transmute the nucleus, a neutron capture crosssection on the nucleus was conceptualized. However,
because both the neutron and LLFPs are unstable, themeasurement of neutron-induced cross-section is quite
challenging. Alternatively, the reaction cross-section canbe indirectly determined through a surrogate reaction.
It is generally assumed that the (n, γ) cross-section
is composed of two parts; the formation of compoundstate and the subsequent decay. The ﬁrst term canbe calculated using the optical model potentials with
global parameterbcharres. In contrast, the theoreticalestimates of the second process is quite challenging owing to high level density and complicated decay scheme,
and need to be evaluated by the experiment.2) This work
aims to determine the γ emission probability, Pγ , fromthe unbound states of 80 Se populated by the (d, p) reaction as a surrogate for the 79 Se(n, γ)80 Se reaction. The
method can be veriﬁed by comparing the cross-sectionsof 77 Se(n, γ)78 Se determined by directly measuring the77
Se(d, p)78 Se reaction with the direct measurement at
En = 550 keV.3)
The experiment was performed by using the OEDO
beam line4) as one of the ﬁrst physics experiments.
The 77, 79 Se beams produced by BigRIPS were energydegraded at F5 and the beam was spatially focusedon a 4-mg/cm2 thick polyethylene deuteride target
by OEDO. The beam energy was adjusted to be
∗1
∗2
∗3
∗4
∗5

∗6
∗7
∗8
∗9

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- 50 -A/Q (arb. u.)

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. Shimoura∗1
2.4

4
3.5

2.35

3
2.5

2.3
2
1.5

2.25

1
2.2
−5

0.5
0

5

10

15

20

25
30
Energy (MeV)

0

Fig. 1. A/Q measured at S1 focal plane as a function of theexcitation energy in 80 Se. See the text for details.

20 MeV/nucleon at the target. The recoiled particles
were identiﬁed by employing the six SSD-CsI(Tl) arraycalled TiNA, which covered 100◦ to 150◦ in the laboratory frame. The excitation energies of the state populated in 78 Se (80 Se) were determined using TiNA andincident beam momentum. The momenta of the outgoing nuclei were analyzed by the ﬁrst half of the SHARAQ
spectrometer.
Figure 1 presents the mass-to-charge (A/Q) ratio determined by the spectrometer as a function of the excitation energy of 80 Se. The locus at A/Q = 2.3 is the80
Se33+ while A/Q = 2.27 is 79 Se33+ . The locus of 80 Se
clearly indicates that 80 Se survived at an energy higher
than 10 MeV of the one neutron separation energy of
80
Se. The fraction of (N +1, Z) nuclei to (N , Z) residues
allows us to determine Pγ as a function of excitation energy. Further analysis is ongoing.
This work was funded by the ImPACT Program ofCouncil for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
References

1) F. Kappler et al., Rep. Prog. Phys. 52, 945 (1989).
2) J. E. Escher et al., Rev. Mod. Phys. 84, 353 (2012).
3) S. Kawada, M. Igashira, T. Katabuchi, M. Mizumoto, J.
Nucl. Sci. Tech. 47, 643 (2010).
4) S. Michimasa et al., Prog. Theo. Exp. Phys., accepted (2019).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Fine tuning of isochronism in Rare RI Ring using resonant Schottky
monitorRare RI Ring (R3)1) is a storage ring that measure
the masses of highly unstable exotic nuclei. According to the r-process, the masses of neutron-rich nuclei are crucial to understand nucleosynthesis. We employed a time-of-flight mass spectrometry method in
an isochronous storage ring (R3). Because the target
precision in mass determination was 10−6 , isochronism
with a precision of 10−6 was required. R3 has a hexagonal symmetric structure that alternates between the
sector section and straight section. The sector section consists of four bending magnets. The two magnets on both ends are equipped with ten trim coils
to tune the isochronous condition. A monitor thatmeasures the isochronous condition with 10−6 precision is required for precise isochronism tuning. Thiscan be achieved through revolution time measurement
for several sample particles with evenly distributed momentum over acceptance. However, it is not practicalbecause it takes a long time. In this paper, we report another way using a resonant Schottky pick-up,2)
which measures the revolution frequency with a precision of 10−6 , to evaluate the isochronism. The revolution frequency of an accumulated single-ion is temporally varied, as already shown in Ref. 3), because themomentum is smoothly decreased with time owing to
the collision with the residual gas under the vacuum
level of 10−5 Pa. The advantage of the new method
is that the isochronism over the full range of momentum acceptance is precisely monitored with a single
event, and the measurement is completed within a few
seconds.
We practically applied this method to measure theisochronism of R3 using 78 Ge32+ beam with an energyof 166 MeV/nucleon, and attempted to fine tune theisochronism. Figure 1 shows the momentum dependence of the revolution frequency. The momentum acceptance of R3 and the beam transport line up to R3 islimited to ±0.3% and the good field region in R3 is provided within ±0.3%. Although a particle with momentum less than −0.3% can be accumulated, its isochronism is unestablished. Therefore, we discuss here theisochronism within the momentum region of ±0.3%.
The black line indicates the momentum-dependent revolution frequency under the expected setting of thetrim-coil current. The initial momentum, which is indicated at the right edge of the plot, was obtained fromthe horizontal position measured at the dispersive focal point F5 in BigRIPS. The third-order correlation
between the revolution frequency and momentum remains. It is suppressed by fine tuning the trim-coil∗1

Relative Frequency [Hz]F. Suzaki,∗1 Y. Abe,∗1 M. Wakasugi,∗1 Y. Yamaguchi,∗1 and the Rare RI Ring collaboration
100
50

Out ofgood field region

0
-50

-100

-0.4

-0.3

-0.2

-0.1

dp/p [%]

00.1

Fig. 1. Revolution frequency as a function of momentum
converted from the accumulation time. The black andred solid lines indicate the revolution frequency before
and after the fine tuning procedure, respectively. Twolines correspond to one event each. We subtracted thecenter frequency of the observational range from eachrevolution frequency. The momentum region less than
−0.3% is out of the acceptance. Third-order correlation between the revolution frequency and momentum
disappeared owing to fine tuning. The isochronism was
obtained to be 5.4 × 10−6 .

current using the known response functions of eachtrim-coil current to the isochronism. Among the ten
horizontally arranged trim coils, the currents for the
inner trim coils were slightly decreased by a few percent and those for the outer trim coils were oppositely
increased in this case. This tuning procedure was repeated for some time. The red line shows the revolution frequency after the tuning procedure and it isnearly constant within the momentum acceptance. We
can reduce the variation in frequency within the momentum acceptance from 46 Hz before tuning to 15 Hz
after tuning. This corresponds to the isochronism of
5.4 × 10−6 . The data outside the acceptance are ignored because they are out of the good field region.
We succeeded in the quick tuning of isochronism witha resonant Schottky pick-up and frequency variation
within the momentum acceptance was easily achievedin the order of 10−6 .
References

1) Y. Yamaguchi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 629 (2013).
2) F. Nolden et al., Nucl. Instrum. Methods Phys. Res. A
659, 69 (2011).
3) F. Suzaki et al., Proc. of 13th Int. Conf. on Heavy Ion
Acc. Tech., 98 (2015).

RIKEN Nishina Center- 51 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Preliminary analysis of the mass measurement experiment in thesouth-western region of 132 Sn with 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
Mass measurement experiments were conducted atRare RI Ring (R3)1) in 2018. Neutron-rich 122 Rh,
123, 124
Pd, and 125 Ag nuclides were measured in two set2)
tings. The principle of the mass masurement in the R3
can be described by the following equation:
�2
m1
m0 T1 �� 1 − β1
=
(1)
�
(
)2
q1
q0 T0
1 − TT10 β1

where T1 and T0 are the revolution times of nucleus ofinterest and reference nucleus, respectively, and β 1 isthe velocity of the nucleus of interest.3) The unknown
mass m1 is determined relative to the mass of reference
nucleus m0 . When a particle is injected into R3 using the
kicker magnet,1) it circulates for approximately 0.7 ms.
The particle is then extracted to ELC using the same
kicker magnet. The detector setup in R3 is shown in
Fig. 1 We measured the time-of-flight (TOF) from F3 to
S0 to determine the velocities of each particle and from
S0 to ELC to determine T1 and T0 .
To obtain the revelotion time of the particle in R3, weneed to know the turn number of each particle before
the extraction. For this purpose, we used detectors at
R-MD4 of R3, which were composed of the E-MCP detector,4) a plastic scintillator, and a CsI(Tl) telescope.
NaI (Beam stop)

Ion chamber
ELC PlaKicker Magnet

S0

E-MCP
E-MCP

Pla.
CsI(Tl) Tele.

Rare-RI Ring (R3)R-MD4

Fig. 1. Schemaic view of the detector setup at R3.
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

Table 1. TOF, revolution times, and deduced turn numbersof nuclide in the two settings.
Nuclei

128

Rev. time [ns]394.00R3 TOF [ns]724922.66 724897.19 724904.61 724904.61

Turns

1840

127

Sn

391.69126In395.28127In

397.642
1823
125

Cd

399.04126

Cd

405.44
1806
124

Ag

402.99125Ag405.44
1788
123

Pd

407.09724293.23 724204.20 724284.13 724561.00 724621.44
1849

1832

1815

1798

1780

First, the telescope detectors and plastic scintillator at
R-MD4 were placed on the central orbit and the injection time spectrum was recorded. Second, the detectors
were moved to the inner side of the ring, 85 mm awayfrom the central orbit, which corresponds to the extraction orbit. The TOF of the nuclei, circulating in R3, canbe determined from these two measurements. Third, we
inserted the E-MCP detector with a thin foil into thecentral orbit of the ring to measure the revolution timeof the nuclei. The turn number of each nucleus wasdetermined based on the TOF obtained by the first two
steps and the revolution time obtained by the third step.
The TOF in the R3, revolution time measured by the EMCP detector, and the deduced turn number are listed
in Table 1. For 122 Rh and 124 Pd, the turn numbers could
not be clearly determined owing to the low statistics ofthe revolution times. However, the revolution times of122
Rh and 124 Pd could be precisely estimated based on
the mean Bρ value and central orbit length, which were
calibrated by the data of other nuclei.
To determine the mass, besides T0, 1 , we also need to
calculate β1 for each event. β1 will be determined by
the TOF between the F3 achromatic focus of BigRIPS
and S0 and the corresponding path length that will becalibrated by the reference nuclei in the future.
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 SurreySn1) Y. Yamaguchi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 629(2013).
2) S. Naimi et al., in this report.
3) A. Ozawa et al., Prog. Theor. Exp. Phys. 2012, 03C009 (2012).
4) Y. Abe et al., JPS Conf. Proc. 1, 013059 (2014).
5) D. Nagae et al., RIKEN Accel. Prog. Rep. 51, 168 (2018).

- 52 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

First online experiment of α-ToF detector with MRTOF-MS
T. Niwase,∗1,∗2 M. Wada,∗3 P. Schury,∗3 Y. Ito,∗4 S. Kimura,∗1 D. Kaji,∗1 M. Rosenbusch,∗1 Y. X. Watanabe,∗3
Y. Hirayama,∗3 H. Miyatake,∗3 J. Y. Moon,∗3,∗7 H. Ishiyama,∗1 K. Morimoto,∗1 H. Haba,∗1 T. Tanaka.∗1,∗2
S. Ishizawa,∗1,∗4 A. Takamine,∗1 K. Morita,∗1,∗2 and H. Wollnik∗5
We have the measured masses of more than 80 shortlived nuclei using a multi reﬂection time-of-ﬂight mass
spectrograph (MRTOF-MS)1) and plan to measure super heavy nuclei. For this purpose, we developed a new
innovative detector, named α-ToF,2) which is capableof performing correlation measurement of the time-ofﬂight signal and successive α decay signals. It can reliably discriminate true events from background events.
The ﬁrst online experiment of the α-ToF detector
was performed at SHE-Mass-II3) coupled with the gasﬁlled recoil Ion Separator GARIS-II.4) A short-lived radium isotope was produced in the 159 Tb(51 V, 5n)207 Ra
reaction by a 219.1 MeV primary beam with an intensity of 1.0 pµA. The 460 µg/cm2 thick Tb target
was produced by sputtering of the target material on
a 3.0 µm thick Ti backing foil. The reaction products(fusion-evaporation residues: ERs) were separated inﬂight from the projectiles and other background products. The ERs were captured in a cryogenic He gas
catcher through Mylar foil windows, and the thermalized ions were extracted from the gas catcher by an
rf-carpet and further transported to the MRTOF-MS
via multiple ion traps.
The SHE-Mass-II facility has a single triplet ion
trap, which directly connects the gas catcher to the
MRTOF to achieve high eﬃciency. However, such conﬁguration might suﬀer from contaminant ions from thegas catcher, therefore, we placed a Bradbury-Nielsen
ion gate between the trap and the MRTOF to reducethe contamination. Unfortunately, the gate was broken just before the measurement due to a discharge
accident. A preliminary time-of-ﬂight spectrum for
207
Ra2+ is shown in Fig. 1. Many background counts
are seen in the raw spectrum (Fig. 1 (a)). On gating
the spectrum by the α-ray energy of 207 Ra with a coincident time of two half-life periods, such backgrounds
were reduced by a factor of 40 (Fig. 1 (b)), while thetrue event number was preserved with 36% eﬃciency,
which agrees with the solid angle of the Si detector andthe limited coincidence time.
Figure 2 (a) shows a part of the two-dimensional
spectrum for the time-of-ﬂight and the α-energy while
Fig. 2 (b) shows a decay time spectrum of 207 Ra. The
decay time is the interval between the time-of-ﬂight
∗1
∗2
∗3
∗4
∗5
∗6
∗7

52.89552.89652.89752.89852.89952.9

52.90152.90252.90352.9041052.905

Fig. 1. A part of the time-of-flight spectrum of 207 Ra. (a) is
a raw spectrum while (b) shows coincident events with
α-rays from 207 Ra for a coincident time of two half-livesof 207 Ra.

Fig. 2. (a)Two-dimensional spectrum of the time-of-flightand α-decay energy. (b) decay spectrum of 207 Ra. The
solid lines indicate the literature values of the decay
profiles, namely T1/2 =1.3 s and 59 ms with an intensity
ratio of 1:20.

signal and the α-ray signal. From this spectrum, thehalf-life of 207 Ra is found to be 1.33(50) s, which agrees
with the literature value.5) We also observed a few
early events, which are consistent with the decay fromthe isomeric state of 207m Ra having a half-life of 59 ms.
In this ﬁrst online experiment, we conﬁrmed thatthe α-ToF detector can reduce the background in atime-of-ﬂight spectrum and obtain decay properties ofshort-lived nuclei.
References

1) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B
335, 39 (2014).
2) T. Niwase et al., RIKEN Accel. Prog. Rep. 51, 157 (2018).
3) M. Wada et al., RIKEN Accel. Prog. Rep. 52, (2019).
4) D. Kaji et al., Nucl. Instrum. Methods Phys. Res. B
317, 311 (2013).
5) F. G. Kondev, S. Lalkovski et al., Nucl. Data Sheets
112, 707 (2011).

RIKEN Nishina Center
Department of Physics, Kyushu University
KEK, Wako Nuclear Science Center
Japan Atomic Energy Agency
Department of Physics, Yamagata University
Department of Chemistry and Biochemistry, New Mexico
State University
Institute for Basic Science, Rare Isotope Science Project- 53 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

β-γ spectroscopy of 195 Os at KISS
M. Ahmed,∗1 Y. X. Watanabe,∗2 Y. Hirayama,∗2 M. Mukai,∗1 J. H. Park,∗3 P. Schury,∗2 Y. Kakiguchi,∗2
S. Kimura,∗4 A. Ozawa,∗1 M. Oyaizu,∗2 M. Wada,∗2 and H. Miyatake∗2
Almost a half of nuclei in nature heavier than iron are
considered to have been synthesized in the rapid neutron
capture process (r-process) under an explosive stellar environment with a temperature higher than 109 K and aneutron density higher than 1020 cm−3 . The r-process
goes through the region of extremely neutron-rich nuclei
under such an explosive condition. The peak at the mass
number of 195, called as the 3rd peak, on the observed
solar r-abundance distribution is considered to be originated from the waiting point nuclei with the neutron
number (N ) of 126 on the r-process path. The astrophysical environment such as the temperature and theneutron density is not known for the formation of the
3rd peak. To investigate those conditions, the properties such as lifetimes and masses of the waiting point
nuclei are important. However, they are too far fromthe β-stability line to experimentally access. Therefore,
some theoretical prediction is employed for the physicalvalues of the nuclear properties concerning the r-process
in order to perform the nucleosynthesis simulation tosurvey the explosive stellar conditions. Thus a reliable
theoretical nuclear model is required to precisely predict those nuclear properties to elucidate the astrophysical environments of the r-process. The region of theneutron-rich nuclei around N = 126 is predicted as acompetitive region of the ﬁrst-forbidden (FF) and theallowed Gamow-Teller (GT) β-decays.1) Such competition makes it diﬃcult to theoretically predict their halflives, and those predicted values in various theoreticalmodels are deviated from each other. The systematic
experimental investigation of nuclear properties of theneutron-rich nuclei around N = 126 is important for theselection of reliable theoretical model and improvementof their predictions.
Neutron-rich osmium isotopes are candidates to study
their nuclear structures because they have the ﬁlled single particle orbits h11/2 for protons, which contribute to
the GT β-transitions for the nuclei around N = 126. We
have performed β-γ spectroscopy of 195 Os at KEK Isotope Separation System (KISS)2) to study its β-decay
scheme, which is unknown so far. The 195 Os isotopes
were produced by multi-nucleon transfer reactions between the 136 Xe beam (50 pnA on target) with energy ofaround 10 MeV/nucleon and a 198 Pt target. They werecollected, separated and extracted by the KISS, and ﬁnally the 195 Os ions of its ground state and isomericstate were transported with the rate of 14(2) cps to themeasurement area. They were implanted into an alu∗1
∗2

∗3
∗4

Department of Physics, University of Tsukuba
Wako Nuclear Science Center (WNSC), Institute of Particle
and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)
Institute for Basic Science (IBS)RIKEN Nishina Center- 54 -

Fig. 1. Meausred γ-ray energy spectra in coincidence with
the MSPGC detector hit patterns M = 1 (red line) andM = 2 (blue line).

minized Mylar tape, which was surrounded by the MultiSegmented Proportional Gas Counter (MSPGC)3) and
four High-Purity Germanium (HPGe) clover detectors.
The MSPGC was used to detect β-rays, X-rays and conversion electrons, and the HPGe clover detectors wereused to detect γ-rays. Figure 1 shows measured γ-ray
energy spectra in coincidence with the MSPGC detector
hit patterns M = 1 (red line) and M = 2 (blue line).
The hit patterns M = 1 and M = 2 are sensitive to Xrays and β-rays, respectively. We have found 28 γ-ray
peaks in total with some characteristic X-rays. 22 γ-ray
peaks denoted by black labels agree with energies in theliterature for γ-rays from 194 Ir(n, γ)195 Ir reactions and
β-delayed γ-rays of 195 Ir. We found 6 γ-ray peaks forthe ﬁrst time. The lifetime measurements and γ-γ coincidence analyses reveal that two of them with blue labels
are β-delayed γ-rays of 195 Os, and four of them with redlabels are γ-rays associated with a newly found isomeric
decay of 195 Os. Further analysis for the β-decay schemeand the isomeric decay of 195 Os is in progress.
References

1) I. N. Borzov, Phys. Rev. C 67, 025802 (2003).
2) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res. B
353, 4 (2015).
3) M. Mukai et al., Nucl. Instrum. Methods Phys. Res. A
884, 1 (2018).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Feasibility study of 199 Pt Q-moment measurement
using in-gas-jet laser ionization spectroscopy at KISS
H. Choi,∗1 Y. Hirayama,∗2 Y. X. Watanabe,∗2 P. Schury,∗2 M. Mukai,∗2 M. Ahmed,∗2,∗3 M. Oyaizu,∗2
M. Wada,∗2 and H. Miyatake∗2
KEK Isotope Separation System (KISS)1) has beendeveloped to study nuclei in the region of neutron magic
number N = 126. We investigated the nuclear structureof 199 Pt and Ir isotopes by measuring their hyperﬁne
structures (HFSs) through the in-gas-cell laser ionization technique.2) In the measurement, we obtained precise values of magnetic dipole moments µ = +0.75(8) µN
and µ = −0.57(5) µN for 199g Pt and 199m Pt, respectively.
However the errors of electric quadrupole moments werequite large, Qg = +1.7(17) b and Qm = +3.5(21) b. To
improve the spectral resolution, we developed an in-gasjet laser ionization spectroscopy technique at KISS. In
the laser system, a diode laser (TOPTICA, DLC DL Pro
HP, 450 nm) is used for the seed laser of a pulsed dyeampliﬁer (Sirah), which creates UV light (λ1 = 225 nm)
for the excitation to the state 5d8 6s6p 5 F2 . A Nd:YAG
laser (EdgeWave) is used to pump the dye ampliﬁer andfor ionization as the second step (λ2 = 355 nm). Compared to in-gas-cell ionization, we improved the resolution from 12.5(5) GHz to 0.6(1) GHz in the full width of
the half maximum owing to the low density and temperature conditions of the gas jet.3) From this result, we are
expecting to obtain a much more precise value of electromagnetic moments and isotope shift for 199 Pt throughthe in-gas-jet laser ionization spectroscopy technique.
The feasibility of 199 Pt HFS measurement throughthe in-gas-jet laser ionization spectroscopy was investigated by the Monte Carlo simulation. Based on the HFS
spread and present resolution of 0.6 GHz by the in-gasjet method, we determined the measurement step ∆ν 1
= 0.27 GHz. From the yield of 199g+m Pt, we determined
the measurement time of 10 min for each data point,
which corresponds to a measurement of 20 h. A Voigt
function with Gaussian width ΓG = 316(27) MHz andLorentzian width ΓL = 110(76) MHz, which were determined from the oﬀ-line measurement of 196 Pt (Iπ =0+ ), was used in a response function of the resonancepeak. Relative intensities between each resonance peakwere computed via the Racah coeﬃcient. We assumed
the unknown electric quadrupole hyperﬁne coupling constant of the atomic excited state of 199g Pt to be 1 GHz.
Figure 1 shows the simulated hyperﬁne splitting spectrum of 199g+m Pt. The vertical axis indicates the expected β-ray events detected by MSPGC4) during the
10 min beam accumulation. The total β-ray events were
evaluated to be 4915 counts. Figure 2 shows the simulated HFS spectrum of 199m Pt nuclei obtained by gat∗1∗2∗3

Seoul National University
Wako Nuclear Science Center (WNSC), Institute of Particle
and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)
Department of Physics, University of Tsukuba

Fig. 1. Simulated HFS spectrum of 199g+m Pt. Red line indicates the simultaneous fitting function.

Fig. 2. Simulated HFS spectrum of 199m Pt obtained by gating on 392-keV γ-ray.

ing on a 392 keV γ-ray. Total γ-ray events detected by
the four super clover Ge detectors were evaluated to be3941 counts. In the analysis, the spectra in Figs. 1 and 2
were simultaneously ﬁtted using the common parameters(electromagnetic hyperﬁne coupling constants) for 199i Pt(i = g, m). The reduced chi-square of ﬁtting was 1.13.
In the simulation, we assumed µg = +0.75 µN and Qg =+1.7 b, and µm = −0.57 µN and Qm = +3.5 b for 199g Pt
and 199m Pt respectively. The evaluated electromagnetic
moments from the ﬁtting were µg = +0.7434(58) µN ,Qg = +1.75(10) b, µm = −0.5740(49) µN , and Qm =+3.42(10) b. From the simulation, we conﬁrmed thatthe 20 h measurement is enough to achieve precise values of electromagnetic moments for 199 Pt.
References

1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res. B
353, 4 (2015).
2) Y. Hirayama et al., Phys. Rev. C 96, 014307 (2017).
3) Y. Hirayama et al., in this progress report.
4) M. Mukai et al., Nucl. Instrum. Methods Phys. Res. A
884, 1 (2018).

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Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Electric field gradient of ZnO crystal measured by β-NQR of 23 Ne
H. Nishibata,∗1 A. Gladkov,∗1,∗2 T. Kawaguchi,∗3 H. Ueno,∗1 Y. Ichikawa,∗1 A. Takamine,∗1 T. Sato,∗1
K. Kawata,∗1,∗4 H. Yamazaki,∗1 W. Kobayashi,∗3 M. Sanjo,∗3 L. C. Tao,∗5 Y. Namamura,∗6 T. Asakawa,∗3
Y. Sasaki,∗3 K. Totsuka,∗3 K. Doi,∗3 T. Yada,∗3 K. Asahi,∗1 Y. Ishibashi,∗7 K. Imamura,∗8 T. Fujita,∗9
G. Georgiev,∗10 J. M. Daugas,∗11 and S. Fujiyama∗12This report presents the results of the experimental
program NP1612-RRC47, which is a part of a project
to measure the ground-state magnetic dipole (µ) andelectric quadrupole (Q) moments of neutron-rich Ne isotopes.
The structures of neutron-rich Ne have attracted
much attention because of their exotic structures in the
ground states, such as large deformation and p-wave
halo, as suggested by some of the experiments.1) In order
to investigate such structures, measurements of µ and Q
moments are one of the most eﬀective ways; however,up to now, there exist no moment data for neutron-rich
Ne isotopes. In our project, we approach the groundstate moments of neutron-rich Ne isotopes by meansof β-detected nuclear magnetic resonance (β-NMR). As
the ﬁrst step of this project, we performed an experiment to determine an appropriate single crystal with
an electric ﬁeld gradient at the Ne stopping site for βNMR measurement of the Ne isotopes. In the present
experiment, we applied a β-NQR method2) to the spinpolarized 23 Ne, whose ground-state moments and spinwere well known.3)
The experiment was performed by using RIKEN projectile fragment separator (RIPS). A radioactive 23 Ne
was produced by the one-neutron pickup reaction of
22
Ne (70 MeV/nucleon) with a 0.25-mm-thick Be target.
The 23 Ne spin polarization was obtained by injecting the
primary beam with a tilt angle of 2◦ with respect to the
Be target at the focal plane F0 and selecting the moray
Staticmagnetic fieldRF coil
ZnO

Cold finger
Plastic scintillator

Spin-polarized 23Ne

Fig. 1. Experimental setup.
∗1

RIKEN Nishina Center
Department of Physics, Kyungpook National University∗3 Department of Physics, Hosei University∗4 Center for Nuclear Study, University of Tokyo∗5 School of Physics, Peking University∗6 Department of Physics, Meiji University∗7 Cyclotron and Radioisotope Center, Tohoku University∗8 Department of Physics, Okayama University∗9 Department of Physics, Osaka University∗10 CSNSM, CNRS/IN2P3, Université Paris-Sud∗11 CEA, DAM, DIF∗12 RIKEN, Condensed Molecular Materials Laboratory∗2

Table 1. Comparison between the experimental |q| and thecalculated ones.
Exp.
31(3)
×1019 [V/m2 ]Calc.
Zn siteO site30
45×1019 [V/m2 ] ×1019 [V/m2 ]mentum of 23 Ne at the dispersive focal plane F1. The
obtained spin polarization of 23 Ne was approximately
8%.
Figure 1 shows a layout of the experimental setup. In
the ﬁgure, the spin-polarized 23 Ne beam comes from left
to right side and stops in a ZnO single crystal in vacuum.
The crystal was cooled down to ∼47 K to achieve a longspin-lattice relaxation time. A static magnetic ﬁeld of
0.5 T was applied to the crystal. An oscillating magnetic
ﬁeld was applied by a pair of coils perpendicular to thestatic magnetic ﬁeld through a vacuum chamber wall,
made of ﬁber-reinforced plastics. The β rays from theβ decay of 23 Ne were detected by two telescopes, which
consist of three 1.0-mm-thick plastic scintillators, placed
at 0◦ and 180◦ along the polarization direction.
The obtained NQR spectrum for the ZnO crystal has
been already shown in the previous report.4) The observation of the resonance indicated that the ZnO single
crystal is available for the Ne NMR measurement andensures suﬃcient spin-lattice relaxation time. From theobtained νQ (= eqQ/h) = 1.08(5) × 103 kHz and theliterature Q moment value of 23 Ne, Q = 145(13) emb,3)
the electric ﬁeld gradient q was obtained as |q| =31(3) × 1019 V/m2 .
For a deeper insight, the obtained electric ﬁeld gradient was compared with those calculated by using thegauge including projector augmented waves (GIPAW)
approach.5) Table 1 compares the experimental electricﬁeld gradient with those calculated for substitutionalsites of Zn and O. As seen in the table, the experimental value is very close to that for the O site. It may
suggest that the implanted 23 Ne tends to stop at thesubstitutional Zn site.
References

1) T. Nakamura et al., Phys. Rev. Lett. 112, 142501 (2014)
and references therein.
2) D. Nagae et al., Nucl. Instrum. Methods Phys. Res. B
266, 4612 (2008).
3) W. Geithner et al., Phys. Rev. C 71, 064319 (2005).
4) H. Nishibata et al., RIKEN Accel. Prog. Rep. 2017, 75(2018).
5) C. J. Pickard, F. Mauri, Phys. Rev. B 63, 245101 (2001).
- 56 -

Ⅱ-1. Nuclear Physics

7

RIKEN Accel. Prog. Rep. 52 (2019)

Be target production to measure 7 Be(d, p) reaction for the primordial
7
Li problem in Big-Bang Nucleosynthesis

A. Inoue,∗1 A. Tamii,∗1 S. Cha,∗2 K. Y. Chae,∗2 S. Hayakawa,∗3 N. Kobayashi,∗1 S. Nakamura,∗1 T. Shima,∗1
H. Shimizu,∗3 H. Yamaguchi,∗3 L. Yang,∗3 and Z. Yang∗1
The overestimation of primordial 7 Li abundance in thestandard Big-Bang nucleosynthesis (BBN) model is oneof the known and unresolved problems. A recent theoretical BBN model predicted a primordial 7 Li abundance
that was approximately three times larger than the recent precise observation.1) Light nuclei were produced up
to 7 Be by nuclear reactions in several hundred seconds
following the Big Bang.
7
Li nuclei were predominantly produced by the electron capture decay of 7 Be in the standard BBN model.
The decay half life of 7 Be, 53.22 days, is much longer
than the timescale of the production of light nuclei after
the Big Bang. Thus, one possible scenario to solve the7
Li problem is that 7 Be was destroyed in the timescale ofthe nuclear reactions. There are several possibilities todestroy 7 Be, for example, the 7 Be(d, p)8 Be, 7 Be(n, α), or
7Be(n, p) reactions.2) We focus on the 7 Be(d, p)8 Be reaction because its contribution is suggested to be larger
than that of 7 Be(n, α)4 He.3,4) The goal of the experimentis to measure the cross-section of the 7 Be(d, p)8 Be reaction in the BBN energy region of 100–400 keV. We plan tomeasure the 7 Be(d, p)8 Be reaction with a 7 Be target because the available data are insuﬃcient for the accuracy
or energy range.5,6) We are also motivated to measure
the reaction in direct kinematics because it implementsa good energy resolution. The method allows us to reconstruct the kinematics of the reaction by measuring
the outgoing proton without measuring the two alphaparticles. We apply the implantation target method to
produce the 7 Be target. 7 Be particles were implanted byirradiating a gold target with a 7 Be beam.

Fig. 2. γ-ray energy spectrum of the implanted 7 Be (red dotted plot) and background spectrum (black dotted plot).

We performed an experiment to produce a 7 Be implanted target at CRIB, Center for Nuclear Study(CNS) in April, 2018.
The experimental setup is
shown in Fig. 1.7) The primary beam was 7 Li2+ at
5.6 MeV/nucleon. The secondary beam was producedby the 1 H(7 Li, 7 Be) reaction. The secondary beam energy was 4.0 MeV/nucleon. The 7 Be beam was directed
on to a 10 µm thick gold target as the host material after an energy degrader made of gold with a thickness of
15 µm and 2 mmϕ collimator determined the implanted
beam position.
We evaluated the amount of implanted 7 Be by detecting 477 keV γ-rays with a LaBr3 detector after the implantation. The γ-ray is emitted in the electron capture process of 7 Be with a branching ratio of 10.5%. We
achieved an implantation of 1.9 × 1012 7 Be particles as
expected after one day of irradiation. Figure 2 shows
the measured γ-ray spectrum. We improved the beam
optics for the the high intensity 7 Be beam since 2017,
which enabled the production of the 7 Be target with ahigh intensity beam.
The 7 Be target was carried to the Japan Atomic Energy Agency (JAEA) to measure the (d, p) reaction in
June, 2018. The outgoing protons were successfully measured by three layered silicon detectors with the thickness of 500 µm each at 2 diﬀerent angles, 30◦ and 45◦ .
Currently, analyses are being conducted to obtain the
cross-section of the 7 Be(d, p) reaction.
References

Fig. 1. Experimental setup at CRIB. The enlarged schematic
picture shows the inside of the F2 chamber.
∗1
∗2
∗3

Research Center for Nuclear Physics, Osaka University
Department of Physics, Sungkyunkwan University
Center for Nuclear Study, Graduate School of Science, University of Tokyo1) R. H. Cyburt et al., J. Cosmol. Astropart. Phys. 11, 012(2008).
2) M. Barbagallo et al., Phys. Rev. Lett. 117, 152701 (2016).
3) S. Q. Hou et al., Phys. Rev. C 91, 055802 (2015).
4) T. Kawabata et al., Phys. Rev. Lett. 118, 052701 (2017).
5) R. W. Kavanagh et al., Nucl. Phys. 18, 493 (1960).
6) C. Angulo et al., Astrophys. J. 630, L105 (2005).
7) H. Yamaguchi et al., Nucl. Instrum. Methods Phys. Res.
A 589, 150 (2008).

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Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

New measurement of 8 Li(α, n)11 B reactions
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
Cross section (mb)

The 8 Li(α, n)11 B reaction is considered to be thekey reaction in the inhomogeneous Big Bang and typeII supernova nucleosyntheses, and we have been providing cross-section data1–7) on this reaction for morethan two decades. The previous results1–7) are summarized in Fig. 1, in which the Gamow-peak widths
are also drawn. The energy regions of T9 = 1 and 2
are important for the Big Bang and supernova nucleosyntheses, respectively.
As shown in Fig. 1, the cross-sections obtained by
the previous experiments have large diﬀerences around
Ecm = 1.0 MeV. The previous experiments were performed by two diﬀerent methods: inclusive and exclusive. The former detected either 11 B1,2) or neutron4,6)
and the latter3,5,7) detected both 11 B and neutron bymeasuring their kinetic energies and angles. The crosssections of the former results are ﬁve times larger thanthe latter ones systematically. We could estimate thatthe sources of the discrepancies might originate fromthe experimental methods, but we have no experimental fact to determine them. To solve this problem, we
designed a new inclusive measurement, in which wemeasured the γ-rays emitted from 11 B∗ s. The previous
experiment did not measure the γ-rays. Therefore thisexperiment will provide new data to understand the8Li(α, n)11 B reaction. Considering that the expected
γ-ray energies are between 2 and 8 MeV, we selecteda large volume 3.5“×8” LaBr3 :Ce detector8) provided
by INFN Milano. We also installed plastic and 6 Li-

800
T 9 =2700

T 9 =1

600

Boyd1)
Gu2)
Mizoi3)Cherubini4)
Ishiyama5)
Cognata6)
DAS7)

500

400

300

200

100

0
0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Ecm (MeV)
Fig. 1. Excitation functions of 8 Li(α, n)11 B reaction.

glass scintillators to detect neutrons by covering wide
energy ranges between a few ten keV to 10 MeV.
This experiment was performed at CRIB in September 2018. We placed a gas-target cell at F3, in which
4
He gas was ﬁlled at a pressure of 1.0 atm. The 8 Li
beam, whose intensity was typically 300 kHz, was produced by the 7 Li(d, p)8 Li reaction. The primary 7 Li
beam had an energy of 6.0 MeV/nucleon and an intensity of 250 particle nA. The D2 -gas production target
had a thickness of 1.9 mg/cm2 . The energies of 8 Li
particles measured inside the 4 He-gas target were between Ecm = 0.9 and 1.9 MeV.
We successfully obtained data with suﬃcient statistics. Although we faced diﬃculties in data analysis owing to the large background originating from thermal
neutrons, we could identify the γ-rays emitted from11 ∗B s. We will further present the results to solve thecontroversial discrepancies.

∗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 Istituto Nazionale di Fisica Nucleare (INFN) - Sezione di
Milano∗5 Dipartimento di Fisica dell’Università degli Studi di Milano∗6 Department of Physics, Sungkyunkwan University∗7 Istituto Nazionale di Fisica Nucleare (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 Research Center for Nuclear Physics (RCNP), Osaka University∗11 Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator
Research Organization (KEK)∗12 Department of Physics, Ewha Womans University∗13 Department of Physics, Osaka University∗14 Institute of Modern Physics (IMP), Chinese Academy of Science (CAS)

References

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

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Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Trojan Horse Method-based study of the 18 F(p, α)15 O reaction at
astrophysical energies: update on the 2015 run
S. Cherubini,∗1,∗2,∗3 G. D’Agata,∗1,∗2 M. Gulino,∗1,∗3,∗4 M. La Cognata,∗1 S. Palmerini,∗1 R. G. Pizzone,∗1
S. Romano,∗1,∗2 R. Spartà,∗1 C. Spitaleri,∗1,∗2 H. Yamaguchi,∗5 K. Abe,∗5 O. Beliuskina,∗5 S. Hayakawa,∗5
D. M. Kahl,∗5 Y. Sakaguchi,∗5 S. Kubono,∗3 D. Suzuki,∗3 N. Iwasa,∗6 K. Y. Chae,∗7 M. Kwag,∗7 H. S. Jung,∗8
D. N. Binh,∗9 V. Guimarães,∗10 and S. Bishop∗11
The ﬁrst experiment where the Trojan Horse
Method (THM)1,2) was applied to measure the crosssection of an astrophysically important reaction,
namely 18 F(p, α)15 O at nova energies,3,4) using a radioactive beam was published in Phys. Rev. C 92,
015805 (2015).
To improve the results of that study, a new experiment was performed at the RIKEN Nishina Center using the CRIB apparatus from the University of Tokyo
during the fall of 2015. Similar to the previous work,
the primary beam of 18 O delivered by the AVF cyclotron was used to produce a 18 F radioactive beamwith intensity in the range of 105 –106 pps.
After the standard CRIB apparatus, the radioactive
beam of 18 F was tracked by two PPACs and ﬁnallyused to bombard thin (100–200 µg/cm2 ) CD2 targets.
The THM aimed to study a suitably chosen reaction
proceeding via a quasi-free mechanism with three bodies in the ﬁnal state1) (18 F(d, α15 O)n in this case) toinfer pieces of information for the purpose of astrophysics, 18 F(p, α)15 O in this case.
The distance between the PPACs was substantially
optimized on the basis of the experience acquired in
the previous experiment. Additionally, detection system based on the ASTRHO (Array of Silicons for Trojan HOrse) setup was upgraded. In particular, 8 bidimensional position sensitive silicon detectors (45 × 45mm2 active area, 500 µm thick, made by Hamamatsu
Photonics K. K., Solid State Division) mounted in asquare geometry were used to detect the outgoing particle with an exit angle of approximately 10◦ to 40◦ . A
set of two double-sided multi-strip silicon detectors (50× 50 mm2 , 500 µm thick, produced by Micron Semiconductor Ltd) was used to detect the particles withexit angle ranging from approximately 4◦ to 10◦ .
One of the main problems encountered in the analysis of data in the previous work came from the existence of various reaction channels with three parti-

cles in the ﬁnal state. Although it was shown thatthe events originating from the reaction channels ofinterest could be disentangled from those from otherchannels by applying various types of cuts in the phasespace, the possibility of having a direct identiﬁcationin the Z of the outgoing particles, at least for the heavier ones, was a major goal in this experiment. To thisend, a ∆E stage was added in front of the double-sided
multi strip detectors mentioned above to ensure thata ∆E-E telescope covered the angles ranging between
approximately 4◦ to 10◦ . This resulted in a higher detection eﬃciency because we could accept regions of
the phase space that had to be discarded in the previous data analysis.
The 2015 experimental run was also optimized tocover the phase of space region relevant to the neutron induced 18 F(n, α)15 N reaction. The importanceof having a method to measure the cross-sections of thereaction induced by neutrons on radioactive species isclear, specially if the half-life of the radioactive isotopes involved in the entrance channel of the reaction
are of the order of 1 h or less.
The experiment was successfully performed in thefall of 2015 over a period of 18 days divided into
two runs. Unfortunately, while we expected to obtainhighly enhanced accumulated statistics with respect tothe previous experiment, the number of relevant THM
events only increased by a factor of approximately 2.
In contrast, the events that can be associated withthe 18 F(n, α)15 N reaction in the THM framework, wereabundant and well discriminated.
The analysis of both channels is being ﬁnalized.
Some preliminary results have been presented at various meetings and conferences, and we plan to publish
the ﬁnal results of these studies within this year.
References
1) R. E. Tribble et al., Rep. Prog. Phys. 77, 106901 (2014).
2) S. Cherubini et al., Astrophys. J. 457, 855, (1996).
3) A. S. Adekola et al., Phys. Rev. C 83, 052801(R) (2011).
4) A. M. Laird et al., Phys. Rev. Lett. 110, 032502 (2013).

∗1

INFN-LNS
Dipartimento di Fisica e Astronomia, Università di Catania∗3 RIKEN Nishina Center∗4 Università di Enna KORE
∗5 Center for Nuclear Study, The University of Tokyo∗6 Department of Physics, Tohoku University∗7 Department of Physics, Sungkyunkwan University∗8 Department of Physics, Chung-Ang University∗9 30 MeV Cyclotron Center, Tran Hung Dao Hospital∗10 Universidade de São Paulo, Instituto de Fı́sica, Departamento de Fı́sica Nuclear∗11 Technische Universität München∗2- 59 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Gamow-Teller transitions in 6 He with PANDORA
L. Stuhl,∗1,∗2 J. Gao,∗2,∗3 M. Sasano,∗2 K. Yako,∗1 Y. Kubota,∗2 Z. Yang,∗2 J. Zenihiro,∗2 V. Panin,∗2
Z. Korkulu,∗2 E. Takada,∗4 H. Baba,∗2 and T. Uesaka∗2
We started a program at RIBF aiming to study the
spin-isospin responses of light drip line nuclei. An experiment1) with 5 days of beam time was approved toinvestigate 11 Li and 14 Be nuclei. The charge-exchange(p, n) reactions at intermediate beam energies (E/A >100 MeV) and small angles can selectively excite theGamow-Teller (GT) states up to high excitation energies
in the ﬁnal nucleus. Therefore, (p, n) reactions in inverse
kinematics applying the missing mass reconstruction2,3)
provide the best and eﬃcient tool to study the B(GT)strength values of unstable isotopes in a wide excitationenergy region, without Q-value limitation. In a pilot
measurement of the mentioned experiment, we studied
the case of 6 He at HIMAC facility in Chiba to investigate the Gamow-Teller transitions in 6 He and commission our new plastic scintillator-based neutron detector PANDORA (Particle Analyzer Neutron Detector
Of Real-time Acquisition)4) and its pulse shape discrimination (PSD) capability.
The secondary beam properties and details of the experimental setup are described in another contribution
in this volume.5) By using PANDORA with our digital
data acquisition system,6) we could detect the neutrons
having kinetic energies of a few tens of keV. Neutronand gamma-like events could be separated by deﬁning
PSDmean value as the arithmetic mean of PSD values1)of two single-end read-outs of each bar. From the measured neutron time-of-ﬂight and recoil angle (in the laboratory angle range of 75◦ –99◦ ), the excitation energyof the residual nucleus can be reconstructed. Figure 1
shows the calculated kinematical correlations for the
6
He(p, n) charge-exchange reaction at 123 MeV/nucleon

Fig. 2. Neutron spectra as functions of both recoil neutronenergy and recoil angle in the 6 He(p, n) reaction without gating on neutron-like events (a) and with gate on
neutron-like events (b).

energy.
Selecting the incident 6 He particles and the identiﬁcation of 6 Li reaction residue produced from the (p, n) reaction, a clear kinematical correlation can be seen on theFig. 2 (a) scatter plot. This matches with the calculated
curve and corresponds to transitions to the ground statein 6 Li. After gating on neutron-like events by PSDmean ,the improvement of the kinematic locus in Fig. 2 (b)presents the eﬀectiveness of PANDORA and its PSD capability. The data shown here were accumulated within
9 h. Further analysis with larger statistics is in progress.
This work was supported by KAKENHI 16H06716
and the Japan Society for the Promotion of Science.
References

Fig. 1. Correlations between recoil neutron energy and laboratory kinematics for fixed excitation energies.
∗1
∗2
∗3
∗4

Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center
School of Physics, Peking University
National Institute of Radiological Sciences (NIRS)- 60 -

1) L. Stuhl et al., RIKEN Accel. Prog. Rep. 48, 54 (2015).
2) M. Sasano et al., Phys. Rev. Lett. 107, 202501 (2011).
3) M. Sasano et al., Phys. Rev. C 86, 034324 (2012).
4) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A 866,
164 (2017).
5) M. Sasano et al., RIKEN Accel. Prog. Rep. 51, 78 (2018).
6) J. Gao et al., RIKEN Accel. Prog. Rep. 51, 146 (2018).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

β-NMR measurements for 21 O at HIMAC
A. Gladkov,∗1,∗2 H. Nishibata,∗1 K. Kawata,∗1,∗3 H. Yamazaki,∗1 T. Sato,∗1 Y. Ichikawa,∗1 A. Takamine,∗1
M. Sanjo,∗1,∗4 W. Kobayashi,∗1,∗4 T. Asakawa,∗1,∗4 Y. Sasaki,∗1,∗4 M. Tajima,∗1 K. Asahi,∗1 and H. Ueno∗1
The interest in the shell evolution in the region ofneutron-rich oxygen isotopes has its origin in the multiple studies on 23 O, which have revealed the anomalous
nuclear properties of this isotope. The appearance ofthe new neutron magic number at N = 16 as well as
the formation of the halo structure in 23 O have been
experimentally indicated.1,2) Thus, the information on
the nuclear structure of the neighboring isotopes, suchas 19, 21 O, can provide the systematic picture of thechange in the nuclear properties in this region.
In parallel with the interest in the nuclear structure, the 21 O isotope has a large potential in materials science studies. Owing to it’s advantages in thebeta-ray-detected NMR measurements, as comparedto other oxygen isotopes with known electromagnetic
moments,3) 21 O appeared to be a good candidate toserve as the electromagnetic probe to investigate theatomic-scale properties of the oxygen-containing systems.
Previously, we have reported on the measurement of
nuclear moments of 21 O at RIKEN RIBF.3) However,even though the obtained values provide certain information on the nuclear structure, the improvements inthe precision of Q-moment measurement are desirable
to successfully implement 21 O in the studies describedabove.
Thus, we prepared and performed precision measurements on the nuclear magnetic dipole and electric
quadrupole moments for the ground-state of 21 O using
the β-NMR method at HIMAC, Chiba. The secondary
beam of 21 O was produced at the SB2 4) separation lineof the facility by using the 22 Ne primary beam on the
1-mm-thick Be target at an energy of 70 MeV/nucleon
and beam intensity of 7.8 · 108 particles per spill. The
isotope separation was done in two stages through themomentum and momentum-loss analyses. The latter
was realized using a 3.5-mm-thick Al wedge-shaped energy degrader installed at the F1 focal plane. Beampurity of nearly 100% was achieved for the secondary
beam after the separation. To ensure the polarizationof 21 O, an emission angle of θ = 2.6◦ ± 1◦ was applied using the beam swinger located upstream of theSB2 beam line and the outgoing momentum window
was selected to be pf = p0 × (0.984 ± 0.020) considering the one neutron pick-up mechanism involved in
the reaction. The particle identification was done using ∆E-ToF. The time of flight (ToF) was measured
between the F1 and F3 focal planes of the beam line.
∗1
∗2
∗3
∗4

After the isotope separation, the secondary beam of
O was delivered to the β-NMR apparatus installed
downstream the beam line. The well-establishedmethod of β-NMR in combination with AFP technique5) was applied to measure the electromagnetic
moments. The following sequence was implemented
in the measurements. The stopper crystal placed in a
5000 G static magnetic field B0 was irradiated by thesecondary beam during the first two spills from synchrotron. After the beam implantation, the oscillating
magnetic field was applied to the stopper perpendicular to B0 by using the tank circuit containing fivevariable remotely controlled vacuum capacitors of 50–
2000 pF. The following six spills (9.9 s) were artificiallyskipped and the β-rays from 21 O β-decay were counted
by the plastic scintillator telescopes located above andbelow the stopper. In the next cycle, the beta-rays
were counted without the application of the RF field
and the ratio between the two measurements was taken
to extract the AP value and therefore, the resonant frequency. The 0.5-mm-thick CaO crystal and 0.5 mmthick TiO2 single crystal were used in the g-factor andQ-moment measurements, respectively.
The analysis of the data acquired during the experiment is in progress and the results will be reported
later.
21

References
1) C. Nociforo et al., Phys. Lett. B 605, 79 (2005).
2) D. Cortina-Gil et al., Phys. Rev. Lett. 93, 062501(2004).
3) A. Gladkov et al., RIKEN Accel. Prog. Rep. 50, 74(2017).
4) M. Kanazawa et al., Nucl. Phys. A 746, 393 (2004).
5) D. Nagae et al., Nucl. Instrum. Methods Phys. Res. B
266, 4612 (2008).

RIKEN Nishina Center
Department of Physics, Kyungpook National University
Center for Nuclear Study, The University of Tokyo
Department of Advanced Sciences, Hosei University- 61 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

RI beam production at BigRIPS in 2018
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
In the autumn beam time, the 238 U beam campaign
was conducted with seven experiments. 134, 136 Sn
beams were produced to study the unbound γ-decaying
states in 133, 135 Sn. The ﬁrst physics experiments using the Rare-RI Ring were performed to measure theprecise masses of 74, 76 Ni, 122 Rh, and 124 Pd isotopes.
The BRIKEN experiment was performed to measure
the beta-delayed multi-neutron emission probabilities
in the rare-earth region using the cocktail beam around165
Pm. The ﬁrst experiment with the VANDLE array
setup was performed to study the beta-delayed neutron emission in the vicinity of 78 Ni using the cocktail
beam around 82 Cu. The 132 Sn beam was used to produce the tertiary 130 Sn beam using a two-step schemewith a momentum-dispersion matching technique5) at
F5. The tertiary 130 Sn beam was delivered to F12
for the magnetic moment measurement using the timediﬀerential perturbed angular distribution method.
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 174 experiments
have been performed so far. Figure 1 shows the RI
beams produced in 2018 at the BigRIPS separator on

The radioactive isotope (RI) beam production at
the BigRIPS fragment separator1) in 2018 is presented
here. Table 1 summarizes the experimental programs
that involved the use of the BigRIPS separator during this period and the RI beams produced for eachexperiment.
In the spring beam time, the 18 O beam campaign
was performed with seven experiments. The 10, 12, 14 Be
beams were delivered to the SAMURAI spectrometerto study the cluster structure of neutron-rich Beryllium isotopes. The 14 O beam was produced to investigate the single-particle structure and nucleon correlation in exotic nuclei using knockout reactions. Cocktail beams of 14 Be, 11 Li, and 8 He were produced tomeasure the spin-isospin responses of the neutron dripline nuclei. 9 C beam was produced to study thesingle-particle structure of 8 B relevant to nuclear astrophysics. Two machine studies were performed to develop the dispersion-matched ion-optical system of the
SRC and BigRIPS.2,3) The BigRIPS group has measured the production cross-sections of the proton-richnuclei for the Li–F region and the momentum distribution of 10 C beam in the machine study.4)
Table 1.

List of experimental programs and RI beams produced at the BigRIPS separator in 2018.

Primary beam
(Period)O
230 MeV/nucleon(May 15 – Jun. 8)
18U345 MeV/nucleon(Oct. 16 – Dec. 10)
238∗1

Proposal No.

CourseNP1612-SAMURAI12R1
NP1512-SAMURAI31
MS-EXP18-03
NP1412-SAMURAI30

SAMURAISAMURAIBigRIPSSAMURAI

MS-EXP18-04

BigRIPS

NP1412-SAMURAI29R1
MS-EXP18-02
NP1712-RIBF162
NP1612-RIBF149
NP1612-RIRING2
NP1612-RIBF148-03
NP1712-RIRING1R1
NP1512-RIBF136
INSPECTION18
NP1712-RIBF143R1

SAMURAIBigRIPSRIKEN Nishina Center- 62 -

RI beams
10,12,14Be, 4HeO
C
14
Be/11Li/8He
17,18
13,14,15
12,13,17,18
F,O,N,
9,10,11,14
8,13,14
7,10,11C,
B,
Be, 6Li
9
C
9
C
14
9

ZeroDegree

134,136

Rare-RI Ring
ZeroDegree
Rare-RI Ring
ZeroDegree
BigRIPS
F12

Ni
Pm
124
Pd, 122Rh
82
Cu
74,76
165

132

Sn

Sn

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Table 2.

Year

238

U

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

4
2
3
4
6
4
11
15
13
13
7
82

124

Xe

86

Kr

Number of experiments performed using RI beams in each year.
78

Kr

70

Zn

1

8

6

1

Ca

4
3
10

2
3
2
1

48

6

1

4

1
4

3
4
6
2

6

36

18

O

1
2
6
3
2
3
7
24

16

O

14

N

3
2

4

He

1

1

1

2

H

1

1
1

5

1

3

Yearly
total
5
6
10
14
8
20
9
17
26
22
22
14
173

Fig. 1. RI beams produced in 2018 and the production yield measured from March 2007 to December 2018at the BigRIPS separator.

the table of nuclides with red squares. The number
of RI beams produced in 2018 is 40. The production
yields for 1608 RI beams have been measured fromMarch 2007 to December 2018 and they are indicatedusing cyan. The yellow color indicates the known isotopes. The number of new isotopes is approximately
140.
References
1) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
2) S. Y. Matsumoto et al., in this report.

- 63 -

3) T. Nishi et al., in this report.
4) H. Takeda et al., in this report.
5) Y. Ichikawa et al., Nature Phys. 8, 918 (2012).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Measurement of production cross-section and momentum distribution of
isotopes produced from 18 O beam

∗1

10

2

10

1

Be
Li

10

-1

10

-2

N

C
B

1

O
F

102
10

N

1

1

He

10-1
10-2
10-3
10

-4

10-6
5

Li

6

7

8

9

C

Be

this workmeasured in the past
EPAX 3.1a
EPAX 2.15
FRACS 1.1

10-5

B

10 11 12 13 14 15 16 17 18 19Mass number
Fig. 1. Production cross-sections of isotopes produced in the18
O + Be reaction. The upper and lower panels show
the results for proton-rich (A/Z ≤ 2) and neutron-rich(A/Z > 2) isotopes, respectively.

1

Yield ratio

The production yields and production cross-sectionsof 6 Li, 7, 10, 11 Be, 8, 13, 14 B, 9, 10, 11, 14 C, 12, 13, 17, 18 N,
13, 14, 15
O, and 17, 18 F produced from an 18 O beam at
230 MeV/nucleon were systematically measured with
the BigRIPS separator.1) By combining with previously
measured cross-sections of other isotopes, the crosssection data of almost all nuclei that can be produced
from 18 O has been completed, except for some stable
nuclei and 3 H. In addition, the momentum distribution
was measured for a wide range for 10 C.
The secondary beam was produced from the 18 O beam
on a 2 mm-thick Be target at F0. The momentum slit
at F1 was set at ±3%. An 8 mm-thick Al achromatic
degrader was used at F1 to purify the secondary beam.
The particle identiﬁcation was performed by using the∆E vs. TOF information in the second stage of BigRIPS. For each cross-section measurement, the Bρ setting was tuned for the peak of the momentum distribution of the target isotope. The production cross-sections
were deduced from the measured production rates andthe transmission eﬃciency of the BigRIPS separator estimated with the simulation code LISE++ .2)
The measured production cross-sections are shown in
Fig. 1. The upper and lower panels show the resultsfor proton-rich (A/Z ≤ 2) and neutron-rich (A/Z > 2)
isotopes, respectively. The ﬁlled circles are the measured data at this time, while open circles are previously
measured ones. The magenta, blue, and green lines are
predictions of EPAX 3.1a,3) EPAX 2.15,4) and FRACS
1.1,5) respectively.
The measured cross-sections of the proton-rich B–O
isotopes are 1/2–1/10 of the EPAX 3.1a predictions.
The closer to the proton dripline, the larger the deviation becomes. The results of FRACS 1.1 are almost
the same as those of EPAX 3.1a, while EPAX 2.15 underestimates the cross-sections of isotopes near the stability line. For the neutron-rich isotopes, all the models
reproduced the measured cross-sections relatively wellcompared to the proton-rich side.
The momentum distribution of 10 C was measured bychanging the ﬁrst Bρ01 from −12% to +12% for the
peak momentum value in 3% steps. The yield ratio tothe peak value is plotted as a function of the momentum
deviation in Fig. 2. The red circles show the measured
values. The distribution was not well reproduced by
the LISE++ calculation with the “Universal parametrization” model6) (green line). We need to modify the σconv
and coef parameters, which correspond to the width andlow-momentum tail of the distribution, to reproduce themeasured distribution (blue line). Detailed analysis is inprogress.

Production cross-section (mb)

H. Takeda,∗1 N. Fukuda,∗1 H. Suzuki,∗1 Y. Shimizu,∗1 D. S. Ahn,∗1 N. Inabe,∗1 K. Yoshida,∗1 and T. Uesaka∗1

RIKEN Nishina Center- 64 -

10-1
10-2
-3

10

-4

10
-15

measured++
LISE originalmodified
-10

-5

0

∆p/p (%)

5

10

15

Fig. 2. Momentum distribution of 10 C produced in the 18 O
+ Be 2 mm reaction at 230 MeV/nucleon. The originalmodel (green line) used in the LISE++ did not reproduce
the measured distribution (red circles) well. Modificationof the parameters were needed (blue line).

References

1) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
2) O. B. Tarasov, D. Bazin, Nucl. Instrum. Methods Phys.
Res. B 266, 4657 (2008).
3) K. Sümmerer, Phys. Rev. C 86, 014601 (2012).
4) K. Sümmerer, B. Blank, Phys. Rev. C 61, 034607 (2000).
5) B. Mei, Phys. Rev. C 95, 034608 (2017).
6) O. Tarasov, Nucl. Phys. A 734, 536 (2004).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Cross-section measurement of neutron-rich isotopes produced from an
RI beam of 132 Sn using a two-step scheme
H. Suzuki,∗1 K. Yoshida,∗1 N. Fukuda,∗1 H. Takeda,∗1 Y. Shimizu,∗1 D. S. Ahn,∗1 T. Sumikama,∗1 N. Inabe,∗1
T. Komatsubara,∗1 H. Sato,∗1 Z. Korkulu,∗1 K. Kusaka,∗1 Y. Yanagisawa,∗1 M. Ohtake,∗1 H. Ueno,∗1
S. Michimasa,∗2 N. Kitamura,∗2 K. Kawata,∗2 N. Imai,∗2 O. B. Tarasov,∗3,∗1 D. P. Bazin,∗3,∗1 T. Kubo,∗4,∗1
J. Nolen,∗5,∗1 and W. F. Henning∗5,∗6,∗1

∗1
∗2
∗3
∗4
∗5
∗6

in this experiment at RIBF and the ones at GSI2) are
shown with the cross-section formulae COFRA1.03) andEPAX3.1a.4) Both formulae reproduce the experimental
cross sections fairly well. Further detailed analyses arein progress.
4

Atomic number (Z )1052Preliminary

3

50

10

48

2

10

46
44

10
128

42
40
2.55

127

Pd

Pd

2.6

2.65

2.7

A/Q

2.75

2.8

2.85

1

Fig. 1. The Z versus A/Q PID plot of 128 Pd setting in ZeroDegree. Partially-stripped contaminants are includedin the plot with the fully-stripped 127, 128 Pd.

102
Sn
AgCd
101
In
RhPd
0
Ru
10
10-1
Tc
10-2
Nb Mo
10-3
10-4
GSI data
10-5 126
Pd
setting
128
Pd setting
10-6 COFRA1.0
Preliminary
EPAX3.1a10-7
95 100 105 110 115 120 125 130 135 140

Production cross section [mb]The production cross sections of neutron-rich radioactive isotopes (RI), including 125–128 Pd produced from aless-exotic RI beam of 132 Sn, were measured using BigRIPS and ZeroDegree at the RIKEN RI Beam Factory(RIBF) in November 2017.
A two-step reaction scheme was proposed1) for the eﬃcient production of mid-heavy very-neutron-rich RIs. In
this scheme, a long-lived neutron-rich RI such as 132 Sn,
whose half-life is 40 s, is produced by an ISOL in the ﬁrst
step, and accelerated by post-accelerators. In the second
step, more exotic nuclei, such as 125–128 Pd, are produced
by a fragmentation reaction. With this scheme, one may
obtain greater yields of very neutron-rich RIs than thoseobtained by direct production through the in-ﬂight ﬁssion of a 238 U beam, which is currently a very popularmethod to produce them. To evaluate the yields of RIs
by the two-step scheme with a 132 Sn beam, we measured the production cross sections of neutron-rich Pd
isotopes beyond 125 Pd, up to which the cross sections
had already been measured at GSI together with theneighboring RIs.2)
In the experiment, the 132 Sn beam was produced
at BigRIPS by the in-ﬂight ﬁssion of a 40-pnA
345-MeV/nucleon 238 U86+ beam impinging on a 4mm-thick Be target. The 132 Sn-beam energy was
278 MeV/nucleon, the intensity was 35 kHz, and thepurity was 50%. The neutron-rich Pd isotopes were
produced by the fragmentation with a 6-mm-thick Be
target at the entrance of ZeroDegree. The particle identiﬁcation (PID) was performed by deducing the atomic
number Z, the mass-to-charge ratio A/Q, and the mass
number A of the RIs based on the TOF-Bρ-∆E-TKE
method in ZeroDegree. Two settings—the 126 Pd setting
and the 128 Pd setting—were applied for measuring thecross sections of 125, 126 Pd and 127, 128 Pd, respectively.
The Z vs A/Q PID plot of the 128 Pd setting is shownin Fig. 1. Many fully-stripped isotopes are observed withthe partially-stripped ones. 127, 128 Pd46+ are well identiﬁed in the plot. The events in the two blobs on theright side of 128 Pd46+ are the H-like ions of 126, 127 Pd45+ .
From the yields of RIs, their transmission in ZeroDegree,
and the beam dose of 132 Sn, the production cross sections were deduced. In Fig. 2, the cross sections obtained
RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo
National Superconducting Cyclotron Laboratory, Michigan
State University
Facility for Rare Isotope Beams, Michigan State University
Division of Physics, Argonne National Laboratory
Physik Department, Technische Universität München- 65 -

Mass number (A)Fig. 2. The experimental cross sections of neutron-rich RIs
produced from 132 Sn beams at RIBF and GSI2) withcross-section formulae COFRA1.03) and EPAX3.1a.4)

References

1) K. Helariutta et al., Eur. Phys. J. A 17, 181 (2003).
2) D. Pérez-Loureiro et al., Phys. Lett. B 703, 552 (2011).
3) COFRA web page, http://www.usc.es/genp/cofra.
4) K. Sümmerer, Phys. Rev. C, 86, 014601 (2012).

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

RIKEN Accel. Prog. Rep. 52 (2019)

Improvement of functionals in density functional theory using inverse
Kohn-Sham method and density functional perturbation theory†
D. Ohashi,∗1,∗2 T. Naito,∗1,∗2 and H. Z. Liang∗2,∗1
0

The density functional theory (DFT) is one of themost successful approaches to calculate the groundstate properties. The ground-state density ρgs andenergy Egs are obtained by solving the Kohn-Sham(KS) equation.1,2) The∫ ground-state energy is givenby Egs = T0 [ρgs ] + vext (r) ρgs (r) dr + EHxc [ρgs ],where T0 is the KS kinetic energy, vext is the externalﬁeld, and EHxc [ρ] is the Hartree-exchange-correlationenergy density functional (EDF). However, the accuracy of DFT calculations depends on the determinationof EHxc [ρ] as it is unknown. The inverse Kohn-Sham(IKS) method was proposed toward the improvementof EDFs. Nevertheless, the actual method to improve
EDFs has not been explicitly determined.
In this work, for the ﬁrst time, a new way to improve EDFs by the combination of the IKS methodand density functional perturbation theory (DFPT) is
proposed. In this method, a conventional ẼHxc [ρ] isassumed to be close enough to EHxc [ρ] and the diﬀerence is considered in the ﬁrst-order DFPT( )with small(1)
λ as EHxc [ρ] = ẼHxc [ρ] + λEHxc [ρ] + O λ2 . In addition, ρgs (r) and Egs are expanded perturbatively. The
perturbation is assumed to not aﬀect the external ﬁeld,and ρgs (r) is assumed to be given.
Under the assumptions, we calculate Egs based on
the ﬁrst-order DFPT and on the IKS method. By com(1)paring them, the following equation for EHxc [ρ] is obtained:∫(1)
δEHxc [ρgs ](1)(1)
λEHxc [ρ̃gs ] − λEHxc [ρgs ] + λρgs (r) drδρ (r)∫
N∑
δ ẼHxc [ρgs ]=ρgs (r) dr− Ẽgs ,εi + ẼHxc [ρgs ]−δρ (r)
i=1

∗1
∗2

−30
−40
−50
0.01

target−20

LDA Exchange
1.4
1.3
1.2
1.1
1.0
0.9
0.01 0.1

ε1st
x /εx

ε1st
x (a.u.)

−10

0.1

1

1

10
10

100
100

rs (a.u.)
Fig. 1. Exchange energy density ε1st
x (rs ) calculated intargetthe first iteration and ratios ε1st(rs ). The
x (rs ) /εx
Hartree atomic unit is used here.

tionally, they are easy to handle owing to their spherical symmetry.
It is found that A1 and α1 are obtained within 7.2%
and 1.0% errors in He-Ne, and within 2.3% and 0.2%
errors in Xe-Rn, respectively, from the LDA results.
The calculated exchange energy density at the ﬁrst
iteration, ε1st
x (rs ), and its ratio to the LDA are shownin Fig. 1 for the pairs of He-Ne and Xe-Rn withdashed and dot lines, respectively, while the LDA
exchange functional is represented with a solid line.
The energy density εx (ρ) and the∫ Wigner-Seitz radius rs are deﬁned as Ex [ρ] = εx (ρ) ρ (r) dr and
1/3
rs = [3/ (4πρ)] , respectively. The Xe-Rn pair reproduces the LDA functional within a few percents.
Moreover, it is found that the ground-state energy
becomes closer to the LDA as the iteration proceeds.
The ground-state energies of He, Ne, Xe, and Rn are
ﬁnally reproduced within 0.4%, 0.003%, 0.002%, and
0.0003% errors, respectively, comparing with 28%, 8%,2%, and 2% errors at the zeroth step. It is also foundthat the ground-state density is improved by the iterations.
To summarize, our method accurately reproduces
the LDA functionals. The accuracy of ground-stateenergies and densities are improved by two to three orders and one to two orders of magnitude, respectively.
This method can be eﬀective for nuclear DFT as well.

where εi is the single-particle energy obtained from
Because it is diﬃρgs using the IKS method.
(1)
cult
to
solve
this
equation,
weassume EHxc [ρ] =∫∑αk[ρ (r)] dr and iteratively determine its
k Akvalue. Finally, ẼHxc [ρ] is improved to be ẼHxc [ρ] +(1)
λEHxc [ρ].
As benchmark calculations, ρgs (r) is calculated
target[ρ] and we attempt to reprofrom the known EHxc
duce it from a less accurate ẼHxc . Here, we use thetargetandHartree and LDA exchange functional as EHxc
the Hartree one as ẼHxc . The pairs of noble-gas atoms
He-Ne and Xe-Rn are used because two unknowns Ai
and αi should be determined at each iteration. Addi†

Targetfrom He and Ne
from Xe and Rn

References
1) P. Hohenberg, W. Kohn, Phys. Rev. 136, B864 (1964).
2) W. Kohn, L. J. Sham, Phys. Rev. 140, A1133 (1965).
3) Y. Wang, R. G. Parr, Phys. Rev. A 47, R1591 (1993).
4) Q. Zhao, R. G. Parr, J. Chem. Phys. 98, 543 (1993).

Condensed from arXiv:1812.09285 [physics.chem-ph]
Department of Physics, The University of Tokyo
RIKEN Nishina Center- 67 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Coulomb exchange functional with generalized gradientapproximation for self-consistent Skyrme Hartree-Fock calculations†T. Naito,∗1,∗2 X. Roca-Maza,∗3,∗4 G. Colò,∗3,∗4 and H. Z. Liang∗2,∗1
10

LDA (%)∆ECx

Recently, it was shown that the Coulomb energy
density functionals of the generalized gradient approximation (GGA) give almost the same accuracy as thatof the exact-Fock energy1) by using the experimental charge density distribution as inputs of the functional. As a step further, we carry out the corresponding self-consistent Skyrme Hartree-Fock calculation byusing the Perdew-Burke-Ernzerhof GGA (PBE-GGA)
Coulomb exchange functional2) instead of the exactFock. The GGA Coulomb exchange functionals havebeen proposed as|∇ρch |,
2kF ρch()1/3
kF = 3π 2 ρch
.

(2)

κ
,
1 + µs2 /κ

∗1
∗2
∗3
∗4

exact (%)
∆ECx

Ca

Sn

O

Ca

Sn

20

40

0.5
0.0
−0.5
−1.0
−1.5
−2.0

0

60

80

100 120 140 160 180

Mass Number A
Fig. 1. Deviation between the PBE-GGA and the LDA,
LDA
∆ECx
, and the deviation between the PBE-GGA andexact
the exact-Fock ∆ECx
, defined as Eq. (4).
exact
ECx − ECx,
ECx
(4)
are shown as functions of mass number A in Figs. 1(a)and (b), respectively.
In conclusion, λ does not have an obvious isospin
dependence, and λ = 1.25 reproduces the exact-Fockcalculation well in general. Here, note that the PBEGGA Coulomb potential is the local potential andhence the(numericalcost of the self-consistent calcula)tion is O N 3 , while the exact-Fock Coulomb potential is the(non-local
potential and hence the numerical)cost is O N 4 . This scheme helps to achieve a better
description and understanding of the observables inwhich the Coulomb interaction plays important roles,
such as the mass diﬀerence of the mirror nuclei and theenergy of the isobaric analog state.
LDA
=
∆ECx

(3)

in order to satisfy some physical conditions.3) Accordingly, the parameter κ = 0.804 is determined for any
value of µ by the Hölder inequality. In contrast, two
diﬀerent values of µ have been widely used in the studies of atoms2) and solids.4) For the PBE-GGA functional, µ = 0.21951 is determined by the random phaseapproximation of the homogeneous electron gas. Since
this µ can be a diﬀerent value for nuclear systems, thefree parameter of the PBE-GGA Coulomb exchange
functional, µ, is multiplied by a factor λ. For the nuclear part, the SAMi functional5) is used in the selfconsistent calculation. For comparison, the exact-Fockenergies are also calculated, where the exact-Fock calculation is carried out using the ﬁrst-order perturbation theory.6)
The deviation of the Coulomb exchange energy ECx
LDA
in the PBE-GGA from that in the LDA, ∆ECx
, and
exact
,
the deviation from that in the exact-Fock ∆ECx
†

O

(b)

1.0

In particular, the enhancement factor F in the PBEGGA Coulomb exchange functional is assumed to be2)
F (s) = 1 + κ −

4

0
1.5

( )1/3∫3e
3
4/3[ρch (r)] F (s (r)) dr,
ECx [ρch ] = −16πε0 π(1)where F is the enhancement factor due to the density
gradient, F ≡ 1 is the hold for the local density approximation (LDA), and ρch is the charge distribution.
Here, s denotes the dimensionless density gradient

exact-Fock
GGA (λ = 1.00)
GGA (λ = 1.25)
GGA (λ = 1.50)

SAMi

6

2

2

s=

(a)

8

LDA
ECx − ECx
,
ECx

exact
=
∆ECx

References
1) T. Naito, R. Akashi, H. Liang,
Phys. Rev. C
97, 044319 (2018).
2) J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett.
77, 3865 (1996).
3) J. P. Perdew, K. Burke, Y. Wang,
Phys. Rev.
B 54, 16533 (1996).
4) J. P. Perdew, et al ., Phys. Rev. Lett. 100, 136406(2008).
5) X. Roca-Maza, G. Colò, H. Sagawa, Phys. Rev. C 86,
031306 (2012).
6) X. Roca-Maza, L.-G. Cao, G. Colò, H. Sagawa, Phys.
Rev. C 94, 044313 (2016).

Condensed from the article in Phys. Rev. C 99, 024309(2019)
Department of Physics, The University of Tokyo
RIKEN Nishina Center
Dipartimento di Fisica, Università degli Studi di Milano
INFN, Sezione di Milano- 68 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Joint project for large-scale nuclear structure calculations in 2018
N. Shimizu,∗1 J. Menéndez,∗1 T. Miyagi,∗1 S. Yoshida,∗2 T. Otsuka,∗3,∗1,∗2 and Y. Utsuno∗4,∗1
We have been promoting a joint project for largescale nuclear structure calculations since the year
2002, based on a collaboration agreement between
the RIKEN Accelerator Research Facility (currently
RIKEN Nishina Center) and the Center for Nuclear
Study, the University of Tokyo. This agreement
was completed successfully in March 2018 successfully.
Based on this project, 62 original papers and 56 proceedings have been published and some are being prepared under various collaborations with many experimentalists (e.g. Refs. 1–3)). In 2018, we performed
several theoretical studies for understanding the nuclear structure. Among these studies, we brieﬂy show
three theoretical achievements: a statistical method
for the uncertainty quantiﬁcation of shell-model studies,4) the development of an ab initio nuclear structure
calculation,5) and the theoretical estimation of nuclear
matrix elements that are required for surveying physics
beyond the standard model.3,6–9)
We proposed a novel method to quantify the theoretical uncertainty stemming from the eﬀective interactions of the nuclear shell model.4) In this method,
the uncertainty is discussed by estimating the probability distribution of the parameter set of the eﬀective
interaction in the multidimensional parameter space.
This enables us to quantify an extent of the agreement between the theoretical results and experimental
data in a statistical manner, and the resulting conﬁdence intervals show unexpectedly large variations.
In addition, we pointed out that a large deviation of
the conﬁdence interval of the energy in the shell-model
calculations from the corresponding experimental data
can be used as an indicator of some exotic property,
e.g., α clustering.
In order to investigate the medium-mass nuclei
based on the underlying nuclear interactions in an
ab initio way, the unitary-model-operator approach(UMOA)5) was developed. In the UMOA, the manybody Hamiltonian is transformed by a unitary transformation such that one-particle-one-hole and twoparticle-two-hole excitations do not occur. We calculated the binding energies and radii of 4 He, 16 O,
and 40 Ca using the similarity-renormalization-group(SRG) evolved chiral eﬀective-ﬁeld-theory interaction
consisting of two-nucleon and three-nucleon forces.
The resulting binding energies and radii were consistent with the recent ab initio results obtained using the same Hamiltonian, and we signiﬁcantly underestimated the radii compared to the experimental
∗1
∗2
∗3
∗4

data. To clarify the origin of this underestimation, we
also calculated the radii using the eﬀective operators
obtained from consistent SRG evolution in two- andthree-body spaces. It turned out that the SRG evolution of the radius operator gives a minor modiﬁcationand the underestimation still remains. For a uniﬁed
description of the binding energies and radii, a further
understanding of the nuclear force itself is essential.
We also studied two-neutrino double-beta decays
and double-electron capture. We developed an effective theory that, based on data on beta decays
and electron capture, describes well measured doublebeta transitions, making predictions for several unknown decays.6) Subsequently, we calculated the double electron-capture half-life of 124 Xe into the ﬁnal nucleus 124 Te.7) Our large-scale shell model results predicted a half-life of about 1022 y, which is shorter thanthat predicted by other theoretical approaches, suggesting that an observation of the double-electron capture of 124 Xe is within the reach of current experimental searches.
In addition, we performed shell-model calculations
to study the possible scattering of dark matter oﬀ
atomic nuclei. These interactions could reveal the nature of dark matter, and we investigated how to discriminate experimentally the signal from diﬀerent dark
matter–nucleus couplings.8) In addition, together with
the XENON collaboration, we analyzed for the ﬁrst
time, the coupling of dark matter particles to the pions exchanged between two nucleons,3) a contributionthat has so far not been constrained experimentally.
Finally, we calculated the more general dark matternucleus interactions that can receive coherent contributions from several nucleons in ﬂuorine, silicon, argon,
germanium, and xenon targets.9)
References
1) Md. S. R. Laskar et al., Phys. Rev. C 99, 014308 (2019).
2) C. Loelius et al., Phys. Rev. Lett. 121, 262501 (2018).
3) XENON collaboration, M. Hoferichter, P. Klos,
J. Menéndez, A. Schwenk, Phys. Rev. Lett. 122 071301(2019).
4) S. Yoshida, N. Shimizu, T. Togashi, T. Otsuka, Phys.
Rev. C 98, 061301(R) (2018).
5) T. Miyagi, T. Abe, R. Okamoto, T. Otsuka, Phys. Rev.
C 96, 054312 (2017).
6) E. A. Coello Pérez, J. Menéndez, A. Schwenk, Phys.
Rev. C 98, 044501 (2018).
7) E. A. Coello Pérez, J. Menéndez, A. Schwenk,
arXiv:1809.04443.
8) A. Fieguth, M. Hoferichter, P. Klos, J. Menéndez, et al.,Phys. Rev. D 97, 103532 (2018).
9) M. Hoferichter, P. Klos, J. Menéndez, A. Schwenk,
Phys. Rev. D 99, 055031 (2019).

Center for Nuclear Study, The University of Tokyo
Department of Physics, The University of Tokyo
RIKEN Nishina Center
Japan Atomic Energy Agency- 69 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)Bubble nuclei within the self-consistent Hartree-Fock mean field plus
pairing approach†

†
∗1
∗2
∗3

22

a) O

0.1

FTHF
FTBCS
FTEP
FTEP-BSk14

Depletion factor

A bubble structure is the depletion of nucleon density at its center, which is caused by the absence ofthe nucleon on the s-orbitals. The peak of the swave function at r = 0 signiﬁcantly contributes tothe nucleon density. Therefore, the absence of the swave creates the bubble structure. The pairing correlation and the low-ling excitations aﬀect this bubble structure. In this report, we study the evolution of the bubble structure within the self-consistent
Skyrme-Hartree-Fock mean ﬁeld (HF) plus pairing correlation. The latter is included in two ways: within the
Bardeen-Cooper-Schrieﬀer theory (BCS) and within
the exact pairing solution (EP)1) at ﬁnite temperature, which are referred to as the FTBCS and FTEP,
respectively. The bubble candidates are the neutronrich 22 O (N = 14, Z = 8) and doubly-magic 34 Si(N = 20, Z = 14) nuclei. The calculations are performed with the Skyrme-type interaction MSk3. The
binding energies (BE) and two proton/neutron separation energies (S2p/2n ) of these candidate nuclei are
ﬁtted to the experimental data by adjusting the parameters GN and GZ of the neutron and proton pairing interactions, respectively. The ﬁnite-temperature
HF (FTHF), whose single-particle occupation numbers follow the Fermi-Dirac distribution, is also used tomake a comparison with the FTBCS and FTEP. The
bubble structure is evaluated by the depletion factor
F = (ρmax −ρcent )/ρmax , where ρmax and ρcent are themaximum and central nucleon densities, respectively.
The numerical calculations are performed within the
FTHF, FTBCS and FTEP for 22 O and 34 Si. The pairing eﬀect is known to be dominant in the region aroundFermi surface so that a truncated space with the level
1d5/2 located below Fermi surface and six levels 2s1/2 ,1d3/2 , 1f7/2 , 2p3/2 , 1f5/2 , and 2p1/2 above it is taken
into account for the neutron shell of 22 O and protonshell of 34 Si. As for the proton shell of 22 O and neutron shell of 34 Si, they are closed and therefore are notaﬀected by pairing. For 34 Si, the experimental value
for the occupation number of the 2s1/2 level has beenmeasured and reported by Mutschler et al.2) The pairing interaction parameter G is adjusted to reproduce
this value, which is used as the initial input. For 22 O,
because the occupation number of the 2s1/2 level is notknown, the calculations are based on reproducing its

0.05

0

0.5

1

T (MeV)

1.5

Depletion factor

L. Tan Phuc,∗1,∗2 N. Quang Hung,∗1 and N. Dinh Dang∗3b) 34SiF T HFF T B CS
FTE P

2

4

0.2

0.1

0

T (MeV)

Fig. 1. The depletion factors of 22 O and 34 Si obtained
within the FTHF, FTBCS and FTEP at diﬀerent temperatures.

BE and S2n values.
The results obtained show that, at T ≃ 0, the depletion factors F within the FTBCS and FTEP reach
19% for proton density in 34 Si and 2% for neutron density in 22 O, whereas the FTHF without pairing produces the value of F at around 24% and 11% for 34 Si
and 22 O, respectively (at T = 0.1 MeV). These results
indicate that the eﬀect of pairing correlation on the
bubble structure is strong in the neutron-rich nucleus
22O, and weak in the doubly-magic nucleus 34 Si. With
increasing T , the bubbles in these nuclei become lesspronounced and completely disappear when T reaches
the critical value TF . The value of TF in 34 Si is around
4 MeV within the FTBCS and FTEP, whereas, for 22 O,
it is 0.57 MeV within the FTBCS and 0.85 MeV within
the FTEP (Fig. 1). This diﬀerence can be explainedby the fact that the BCS pairing gap ∆ collapses when
T reaches a critical value Tc = 0.57∆ (T = 0), whichmakes the depletion factor coincide with that predictedby the FTHF, whereas the EP pairing gap is always
ﬁnite with increasing T . This phenomenon causes a
signiﬁcant diﬀerence in TF for the neutron-rich nucleus
22
O, where the pairing correlation is dominant. On theother hand, this phenomenon does not seem to takeplace in the doubly-magic nucleus 34 Si. The BSk14 interaction, which is also used in predicting the neutron
bubble in 22 O, shows a small pairing in this nucleus
instead of strong pairing obtained by using the MSk3
interaction. This indicates that the MSk3 is more suitable than the BSk14 in our study.
References
1) A. Volya, B. A. Brown, V. Zelevinsky, Phys. Lett. B
509, 37 (2001).
2) A. Mutschler et al., Nature 13, 152 (2017).

Condensed from the article in Phys. Rev. C 97, 024331(2018)
Duy Tan University, Ho Chi Minh City, Vietnam
University of Science - Vietnam National University, Ho Chi
Minh City, Vietnam
RIKEN Nishina Center- 70 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Dineutron correlation and large quadrupole collectivity in deformed Mg
isotopes near neutron drip line
M. Yamagami∗1
Dineutron correlation is one of the exotic features innuclei near the neutron drip line. The pair excitation
into continuum states plays a key role in creating thestrong spatial correlation between two neutrons. Dineutron correlation is considered to be a universal phenomenon around the drip line but the experimental evidence is still under intense debate except for light mass
nuclei. In this study, we discuss low-lying quadruple excitations in deformed Mg isotopes to clarify the continuum eﬀects in pairing correlation, which could suggest
the presence of dineutron correlation.
First, we solve the Hartree-Fock-Bogoliubov (HFB)
equation with Skyrme energy density functional (EDF).
We demonstrate the result using the SkM* EDF but the
UNEDF0 EDF draws the same conclusion. The pairingcorrelation is active for single-particle states whose en(+)
ergy ε satisﬁes ε < λ + Epair . Here, λ is the chemical

Fig. 1. K π = 0+ isoscalar quadrupole transition strengths(+)
with Epair = 10 MeV in 40, 42, 44 Mg. QRPA strengths
ignoring the dynamical pairing eﬀect are compared.

(+)

potential and Epair = 10 MeV is used. The predicted
neutron drip line nucleus is 44 Mg with neutron chemical
potential λn = −0.15 MeV. The quadrupole deformations of 34, 36, 38, 40, 42, 44 Mg are β2 = 0.35, 0.30, 0.28,
0.28, 0.21, and 0.15, and the neutron pairing gaps are∆n = 1.21, 1.20, 1.17, 0.98, 1.05, and 1.00 MeV respectively.
On top of the HFB states, we solve the quasiparticle random phase approximation (QRPA) equation
Fig. 2. Summation of strength SIS2 (6 MeV) in neutron-richin the matrix form.1) Figure 1 shows the K π = 0+
Mg isotopes are shown. Eﬀects of continuum states andIS
isoscalar quadrupole transition strength B(Q 2; Eν ) =pairing correlation are investigated.
| ⟨ν| r2 Y20 |0⟩ |2 to the excited state |ν⟩ at excitation energy Eν in 40, 42, 44 Mg. The QRPA excitation is gen(+)
Epair = 10 MeV. It should be noted that the singleerated by the coherent superposition of excitations ofparticle state with ε ≈ 10 MeV has a wave number
both particle-hole and particle-particle types. The trank ≈ 0.27 fm−1 and the spatial size ∆x ≈ 1/k ≈ 3.7 fm
sition strengths without the dynamical pairing eﬀects,
corresponds to the diameter of a dineutron predicted
i.e., QRPA calculation ignoring the residual pairing inaround 40 Mg.2)
teractions, are also shown.
Figure 2 also shows the SIS2 (6 MeV) of RPA
It should be noted that the transition strength of lowand QRPA ignoring the dynamical pairing correlation.
lying states signiﬁcantly reduces when the dynamical
These two results coincide with each other except for
pairing eﬀect is ignored. This excitation mode is in44
Mg. SIS2 (6 MeV) increases by 38.9% when static pairduced by the ﬂuctuation of neutron-pair occupation ining correlation is added in 44 Mg. This is due to an addiNilsson orbits with diﬀerent spatial shapes. For examtional particle-hole conﬁguration from the resonant stateple, the prolate-type orbits [310]1/2 and [301]1/2, and[321]1/2 to resonant state [301]1/2.
the oblate-type orbit [303]7/2 are the main contributors
In conclusion, the coupling to continuum states inaround 40 Mg.
pairing
correlation enhances the low-lying transition
(6
MeV)
=
Figure2shows
thesummationofstrengthS
IS2∑
IS34, 36
strengthsof K π = 0+ isoscalar quadruple excitations
B(Q
2;
E
).
In
Mg,
the
typicalν
0<Eν <6 MeV(+)
in Mg isotopes near the neutron drip line. This suggests
model size for stable nuclei, Epair = 4 MeV, gives reathe presence of dineutron correlations.
sonable results. The eﬀect of continuum states above(+)

Epair = 4 MeV becomes gradually sizable as it approaches the drip line. SIS2 (6 MeV) converges with∗1

Department of Computer Science and Engineering, Universityof Aizu- 71 -

References

1) M. Yamagami et al., RIKEN Accel. Prog. Rep. 50, 92(2017).
2) M. Yamagami et al., Phy. Rev. C 77, 064319 (2008).

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Isoscalar and isovector spin responses in sd-shell nuclei†
H. Sagawa∗1 and T. Suzuki∗2
The spin-isospin response and spin-isospin dependent interactions in nuclei are important fundamental problems in nuclear physics and astrophysics. Recently, isoscalar (IS) and isovector (IV) spin M1 transitions have been investigated by high-resolution proton
inelastic scattering measurements at Ep = 295 MeV.1)
In this study, the spin magnetic dipole transitions andneutron-proton spin-spin correlations in sd-shell eveneven nuclei with N = Z, 20 Ne, 24 Mg, 28 Si, 32 S, and36
Ar along with a p-shell nucleus 12 C are investigatedusing shell model wave functions considering the enhanced IS spin-triplet pairing with eﬀective spin operators. In general, the calculated results show good
agreement with the experimental energy spectra in
N = Z nuclei as far as the excitation energies are concerned. In comparison with the experimental M1 results, the accumulated IS spin strengths up to 16 MeVshow small quenching eﬀect, corresponding to the effective quenched operator f IS (eﬀ) ∼ 0.9, while a large
quenching f IV (eﬀ) ∼ 0.7 is extracted for the IV channel. Similar quenching on the IS spin M1 transitions
is obtained by the 20% enhanced IS spin-triplet pairing correlations with the bare spin operator. However,
the enhanced IS pairing does not change much the excitation energy spectra. The Towner’s eﬀective spin
operators eﬃciently reproduce the accumulated experimental IV spin strength, while the quenching of eﬀective operators is much larger than that observed in the
IS spin channel. Consequently, an enhanced IS spintriplet pairing interaction enlarges the proton-neutron
spin-spin correlation deduced from the diﬀerence between the IS and IV sum rule strengths. The betadecay rates and the IS magnetic moments of sd-shell
are also studied in terms of IS pairing and the eﬀective spin operators. Previously, a large quenching ofIS magnetic transition strength was suggested in theliterature. However, the (p, p′ ) data in Ref. 1) do notexhibit the large quenching eﬀect on the IS spin transitions. This should further be studied experimentallywith possible IS probes such as (d, d′ ) reactions withcomprehensive theoretical calculations.

10

S(σ)

8

∗2

6
4

0

16

20

10

S(στ)

24

28
A

32

EXP
USDB
USDB*qiv
USDB**qiv

8

36

40

(b)

6
4
2
0

16

20

24

28
A

32

36

40

Fig. 1. (Color online) Accumulated spin-M1 transition
strengths of (a) IS channel and (b) IV channel. Experimental and theoretical data are summed up to
Ex = 16 MeV. Shell model calculations are performed
with USDB eﬀective interaction: (a) in the results of
USDB* and USDB*qis, the IS spin-triplet pairing interaction is enhanced by multiplying the relevant matrix
elements with a factor of 1.1 compared to the original USDB interactions, and the quenching factor fsIS
= 1.0 and 0.9 for IS spin operator, respectively. For
USDB**qis, the IS pairing interaction is enhanced bya factor of 1.2 and a quenching factor fsIS = 0.9 is introduced for the IS spin operator. Experimental data
are taken from Ref. 1). Long thin error bars indicate
total experimental uncertainty, while short thick error
bars denote the partial uncertainty from the spin assignment. (b) Eﬀective IV operators2) are adopted for
spin, orbital and spin-tensor operators for USDB*qiv
and USDB**qiv. For the results of USDB*qiv andUSDB**qiv, the IS pairing interaction is enhanced bya factor of 1.1 and 1.2, respectively, using the eﬀective
operators.

References

∗1

(a)

2

1) H. Matsubara et al., Phys. Rev. Lett. 115, 102501(2015) and private communications.
2) I. Towner, Phys. Rep. 155, 263 (1987).
†

EXP
USDB
USDB*
USDB*qis
USDB**qis

Condensed from the article in Phys. Rev. C 97, 054333(2018)RIKEN Nishina Center and Center for Mathematics andPhysics, University of Aizu
Department of Physics, College of Humanities and Science,
Nihon Univerity and National Astronomical Observatory ofJapan- 72 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Self-consistent constrained HFB in odd-A nuclei†
K. Sugawara-Tanabe∗1,∗2 and K. Tanabe∗3
All existing constrained Hartree-Fock-Bogoliubov(CHFB) calculations neglect the Fock or the exchange
terms. Here, the constraint conditions are applicable to the proton number Z, neutron number N ,and the√angular momentum along the chosen x-axis⟨Ix ⟩ = I(I + 1). The numerical calculations startfrom the spherical single-particle basis and include
the residual quadrupole-quadrupole (Q-Q), monopolepairing (MP), and quadruple-pairing (QP) interactions.1) In the approximation without the exchange
2
terms, only the terms Y02 and Y22 + Y−2
in the Q2
Q interaction are considered but the terms Y12 ± Y−1
2
and Y22 − Y−2
are not. We have developed the code
to include all exchange terms in the residual interactions. The exchange terms of Q-Q contribute to
the self-energy Γ and the gap ∆, and those of MP
and QP to Γ . Then, the√ constraint on angular moI(I + 1) − ⟨Iz2 ⟩. We chosementum ⟨Ix ⟩ becomes
the signature invariant base that reduces the diagonalization space to half2) because the total Hamiltonian
with three constraints H ′ is invariant under the operator Rx = exp(−iπIx ). All input matrix elements
are rewritten in this base and the spherical singleparticle operator in this base∑Ck is transformed to†quasiparticle operators αi† =k>0 (Ck Aki + Ck̂ Bki )∑and αî† = k>0 (Ck̂† Âki + Ck B̂ki ), where the notation

50
135

40

I

30

20

10
Theory
Exp.

0
0.0

∗3

1.5

2.0

−0.23 MeV. The strength of QP is 10% of MP, expressed in terms of MeV/b4 and the strength of QQ
is χππ = −0.030 MeV/b4 , χνν = −0.032 MeV/b4 ,and χπν = −0.100 MeV/b4 with an oscillator lengthb. These numerical results are consistent with the experimental data except for the I = 15/2− state. The
constraint on the proton number Z is eﬀective but thevalue of Z for + and − parity states is mixed owing(0)
to Gπ+π− . For example, Z+ = 13.58 and Z− = 17.42
at I = 15/2− , while Z+ = 13.99 and Z− = 17.01 at
I = 55/2− , where Z = Z+ + Z− is the proton number outside the magic number 28. For better results,
another constraint on Z− should be included or the
MP and QP interactions between the + and − parity
states should be dropped. This calculation is preliminary and there is room for ﬁnding better parametersets.

no ωjx , i.e., without constraint on ⟨Ix ⟩, h2 , Λ̂, Â, andB̂ are reduced to h1 , Λ, A, and B, respectively. The
iteration procedure in the numerical analysis is basedon the gradient method.3)
Figure 1 compares I versus transition energy ∆E =E(I) − E(I − 2). The parameters are the same spherical single-particle energy as listed in Table 1 in Ref. 1).
(0)
(0)
(0)
The strength of MP is Gπ+π+ = Gπ−π− = Gπ+π− =
(0)
(0)
(0)
−0.22 MeV and Gν+ν+ = Gν−ν− = Gν+ν− =

∗2

1.0

Fig. 1. Backbending plot for I as a function of energy difference ∆E = E(I) − E(I − 2). Experimental data istaken from Ref. 4).

where h1 (h2 ) includes the spherical single-particle energy and ∑self-energy Γ and ω is the Lagrange multiplierfor Ix = k,l>0 (jx )k,l (Ck† Cl − Ck̂† Cl̂ ). When there is

∗1

0.5

E MeV

k̂ is the time reversal of k. Then, the CHFB equation
becomes:
)( ∗
)
( 1
B̂
A
∆T
h − ωjx∆∗−h2∗ − ωjx
Â∗ B
( ∗
)(
)
B̂
A
−Λ̂ 0
=
,
(1)
0 Λ
Â∗ B

†

Pr

Yrast 11 2 band

References
1) K. Tanabe, K. Sugawara-Tanabe, Prog. Theor. Phys.
83, 1148 (1990).
2) A. L. Goodman, Nucl. Phys. 86, 5866 (2001).
3) H. J. Mang, B. Samadi, P. Ring, Z. Physik A 279, 325(1976).
4) C. S. Paul et al., Phys. Rev. C 84, 047302 (2011).

Condensed from the talk in Int. Symp. on “Simplicity, Symmetry and Beauty,” Sept. 26–28, Shanghai (2018)
RIKEN Nishina Center
Department of Information Design, Otsuma Women’s University
Department of Physics, Saitama University- 73 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Nuclear symmetry energy and the breaking of the isospin symmetry:
how do they reconcile with each other ? †X. Roca-Maza,∗1 G. Colò,∗1 and H. Sagawa∗2
The density dependence of symmetry energy is still
not understood well enough. A deeper understandingis highly needed, because an accurate characterizationof the symmetry energy entails profound consequences
for the study of neutron distributions in nuclei along
the entire nuclear chart, as well of other properties ofneutron-rich nuclei.1) The symmetry energy is also ofparamount importance for understanding the properties of compact objects like neutron stars; it directly
aﬀects the determination of the radius of a low-mass
neutron star.2)
The isobaric analog state (IAS) is one of the wellestablished properties of nuclei that is measured accurately, and it is dominantly sensitive to the isospin
symmetry breaking (ISB) in the nuclear medium due
to Coulomb interaction.3) If there is an inconsistency
between the properties of the symmetry energy andour knowledge of the IAS and ISB forces, it is a serious issue. As discussed often, the neutron skin isstrongly correlated with the density dependence of thesymmetry energy. Therefore, we cannot accept thatthe values of the neutron skin do not match our understanding of the isospin symmetry, which is one of
the basic symmetries of nature, and its breaking.

Fig. 1. Energy of the IAS as a function of ∆rnp with various
EDFs. The arrows indicate the experimental results;
PRex is obtained from the polarized electron parity violation experiment, Dipole polarizability is the value
obtained from the measurement of giant dipole resonances, and elastic p scattering is the data obtained
from the polarized proton scattering cross section analysis.

Starting from the prototype SAMi functional, a systematically varied family was generated, by keeping asimilar quality of the original ﬁt and varying the valuesof J and L. In addition, a family based on the systematic variation of J and L with respect to a relativistic mean ﬁeld (RMF) model with density-dependent
meson-nucleon vertices (DD-ME) was also introduced.
These functionals provide the values of the neutron
skin through the Hartree-Fock (HF) or Hartree solution for the ground-state; in addition, they provide, self-consistently, the IAS energy via the chargeexchange random phase approximation (RPA). The results for the IAS energy, EIAS , as a function of ∆Rnp
are plotted in Fig. 1. The results associated with otherSkyrme interactions are also plotted. We found a serious discrepancy of (0.5∼1) MeV between the calculated and experimental EIAS for all EDFs in Fig. 1.
To solve this puzzle, we reconsidered all possible contributions to the IAS energy that have not been considered with suﬃcient care in self-consistent calcula†∗1∗2

tions so far. Then, we proposed a new parametrization SAMi-ISB for Skyrme-like EDF, which reconciles
standard nuclear properties (saturation density, binding energy, and charge radii of ﬁnite nuclei) with both
our current understanding of the density behavior of
the symmetry energy and the reproduction of the IAS
energy of 208 Pb. We have self-consistently included
for the ﬁrst time within the HF+RPA framework, all
known contributions that break the isospin symmetry.
All of these contributions have been calculated in amodel-independent way. We have ﬁxed only two freeparameters in the charge symmetry breaking (CSB)
and charge independence breaking (CIB) terms, andwe have shown that this allows for a good reproduction of the IAS energy of 208 Pb without compromising
the other properties of nuclear matter and ﬁnite nuclei.
The calculated results show a ﬁne agreement with theexperimental excitation energy of IAS in 208 Pb reconciling realistic symmetry energy parameters and theneutron skin as shown in Fig. 1. The energies of IAS
in Sn isotopes are also improved by SAMi-ISB.

Condensed from the article in Phys. Rev. Lett. 120, 202501(2018)
Dipartimento di Fisica, Università degli Studi di Milano and
INFN, Sezione di Milano
RIKEN Nishina Center and Center for Mathematics andPhysics, University of Aizu

References
1) Bao-An Li et al., Eur. Phys. J. A 50, 9 (2014).
2) C. J. Horowitz et al., J. Phys. G 41, 093001 (2014).
3) N. Auerbach et al., Phys. Rev. Lett. 23, 484 (1969).

- 74 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Neutron-proton pairing correlations and deformation for N = Z
nuclei in pf -shell using deformed BCS and HFB approach†
E. Ha,∗1 M. -K. Cheoun,∗1 and H. Sagawa∗2
Shell evolution by deformation is an important concept to understand the structure of neutron-rich nuclei, whose deformation can be conﬁrmed by rotationalenergy spectra and the E2 transition probability extracted from the experiments. The shell evolution
plays a crucial role in understanding the beta-decays
in nucleosynthesis. Such features may also appear inneutron-deﬁcient deformed nuclei, for example, N = Z
pf -shell nuclei. In particular, in RMF calculations,68
Se and 72 Kr are claimed to have oblate deformations
while 48 Cr, 52 Fe, and 64 Ge may have prolate deformations, as presented in Table 1.
In this work, we determine the most stable deformation by investigating the evolution of ground stateenergies along with the deformation within a framework of the deformed BCS (DBCS) and deformed HFB(DHFB) models. Speciﬁcally, 64 Ge is known to cause
a bottle-neck on p- or α-nucleosynthesis. Then, theneutrino-proton (νp)-process, ν̄e + p → n + e+ , produces lots of neutrons which make it possible to escape the bottle-neck by 64 Ge (n, p) 64 Ga (p, γ) 65 Ge
reaction and subsequently, bridge the waiting points.
Therefore, the nuclear structure of 64 Ge becomes the
key to understand the mechanism of these reaction.
First, we studied the evolution of single particle state(SPS) energies for N = Z pf -shell nuclei by exploitinga deformed Woods-Saxon potential. Second, taking
these SPS, we calculated the ground state energies of
the nuclei including the pairing interactions of like- (nnand pp) and unlike-pairs(np) by the deformed BCS (orHFB) approach. The pairing correlations were foundto be sensitive to the deformation parameter β2 andthe evolved Fermi energies ϵf .
The pairing eﬀects of like-pairs bound the nucleus
more strongly, but did not signiﬁcantly change the evolution of ground state energies. In contrast, the np
pairings contributed to the formation of more boundnuclei and signiﬁcantly aﬀected the pf -shell deformation. To determine the importance of T = 0 pairing, we introduced an enhanced T = 0 pairing interaction, where the T = 0 pairing matrices obtained by the
Bruckner HF calculations were enlarged by a factor of
1.5. We found that the enhanced T = 0 pairing correlations, which played vital roles in the determination of
nuclear deformations of sd-shell nuclei,1) are importantin the evolution of nuclear deformation. Speciﬁcally,†∗1∗2

Table 1. Deformation parameter from the experimental
E2 transition data2) and theoretical deformation parameters by Relativistic Mean Field (RMF),3) FRDM
model,4) and the present results with the enhanced T= 0 pairing for N = Z pf -shell nuclei. Empirical pairing gaps deduced from the five-point mass formula5) arealso shown.
A
Ti
48
Cr
52
Fe
64
Ge
68
Se
72
Kr
76
Sr
44

β2E2
0.277
0.340
0.230
0.259
0.239
0.330
0.443

β2RM F
0.000
0.225
0.186
0.217
–0.285–0.3580.410

β2F RDM
0.011
0.226–0.0110.207
0.233–0.3660.402

β2ours
0.2
0.2
0.2
0.1
–0.2
–0.1
0.1

∆emp
p
2.631
2.128
1.991
1.807
1.909
2.001
1.626

emp
δnp
2.068
1.442
1.122
1.435
1.522
1.353
0.715

the oblate deformations of 68 Se and 72 Kr and prolate
deformations of 52 Fe and 64 Ge could not be explained
without the enhanced T = 0 pairing correlations in thepresent model. Finally, the HFB approach including
pairings between diﬀerent states does not provide any
new eﬀects on the nuclear structure but contributes
to a more reasonable renormalization of the strengthparameter for the nuclear interaction in the nuclear
medium.
In conclusion, the evolution of ground state energies is determined by the evolution of the outermost
shell. The np pairing interactions signiﬁcantly change
the evolution of deformation. In particular, the enhanced isoscalar spin-triplet pairing is shown to play
an important role in changing the shape of the pf -shell
N = Z nuclei such as 68 Se and 72 Kr. It is also suggested by the study of pairing gaps that the IS condensation by the enhanced T = 0 pairing may happen inboth sd-shell and pf -shell nuclei. The state dependent
pairing correlations induced by HFB model are foundto rarely aﬀect the nuclear structures as compared tothe conventional BCS approach.
References
1) E. Ha, M. K. Cheoun, H. Sagawa, Phys. Rev. C 97,
024320 (2018).
2) B. Pritychenko et al., Atomic Data Nucl. Data Tables 107, 1 (2016).
3) G. A. Lalazissis, S. Raman, P. Ring, Atomic Data andNucl. Data Tables 71, 1 (1999).
4) P. Möller, J. R. Nix, W. D. Myers, W. J. Swiatecki,
Atomic Data and Nucl. Data Tables 59, 185 (1995).
5) M. K. Cheoun et al., Nucl. Phys. A 561, 74 (1993); A
564, 329 (1993); M. K. Cheoun et al., ibid. A 587, 301(1995).

Condensed from the article in Phys. Rev. C 97, 064322(2018)
Department of Physics and Origin of Matter and Evolutionof Galaxy (OMEG) Institute, Soongsil University
RIKEN, Nishina Center and Center for Mathematics andPhysics, University of Aizu

- 75 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Spin-singlet and spin-triplet pairing correlations on shape evolution in
sd-shell N = Z Nuclei†
E. Ha,∗1 M. -K. Cheoun,∗1 and H. Sagawa ∗2,∗3
Pairing correlations play an important role in nuclear structure, and have an important eﬀect on nuclear electro-magnetic (EM) and weak transitions.
The pairing correlations are classiﬁed into like-pairing(neutron-neutron (nn) and proton-proton (pp)) andunlike-pairing (neutron-proton (np)) correlations. In
particular, for N = Z nuclei, the np pairing may become signiﬁcant because protons and neutrons occupy
the same orbital and have the maximum conﬁguration
overlap, which is important especially for the T = 0
pairing. The nn and pp pairings have isovector (IV)spin-singlet (T = 1, J = 0) mode, while the np pairing correlations have peculiar isoscalar (IS) spin-triplet(T = 0, J = 1) as well as IV spin-singlet mode. Overthe last few decades, there have been many discussions
regarding the np pairing correlations, in particular, thecoexistence of IS and IV correlations and their competitions in some speciﬁc nuclear observables.
Recently, interesting experimental data have beenreported, which show more quenching in the IV M1
spin transition data for the N = Z sd-shell nuclei1)
than the IS data. These features are not expectedaccording to former theoretical discussions.2,3) It waspointed out in Ref. 4) that the T = 0 pairing plays
a signiﬁcant role to cause these features in the spin
dependent observables.
We studied the shape evolution of N = Z nuclei,
24Mg, 28 Si, and 32 S in the deformed Woods-Saxon(DWS) and deformed BCS (DBCS) approximations
taking into account both T = 0 and T = 1 pairingcorrelations. In the ﬁlling approximation for the DWS
potential, it is shown that the shape evolution strongly
correlates with the shell structure of s.p. energies near
the last occupied orbit (Fermi energy). The eﬀect of
two types of pairing correlations with isospin T = 0
and T = 1 are studied by the DBCS model with Gmatrix-based pairing interactions. We adopted an enhanced T = 0 pairing interaction to clarity the eﬀect of
T = 0 pairing on the ground state energy. In Fig. 1, weused a stronger T = 0 interaction (50% stronger thanthe G-matrix results4) ), which makes the pairing correlations more transparent, especially at the large prolate
deformation and leads to the deep prolate deformation
minimum in 24 Mg. A drastic change in the pairing correlation energy is induced by the active T = 0 pairing
channel on top of the usual T = 1 channel, implying
†
∗1
∗2
∗3

Fig. 1. The ground state energy (Etotal = EMF′ +Epair ) for24
Mg by the DBCS model with Woods-Saxon potential.
Mean field energy by the DBCS is denoted as EMF′ .
Epair is the pairing energy in the right y-axis. The
pairing energies are estimated with enhanced T = 0
pairing in np channel.

that the two paring channels co-exist in the large deformation region.
In summary, we found a coexistent phase of two
types of superconductors in the large deformation region |β2 | > 0.3 in 24 Mg, 28 Si and 32 S with the enhanced
T = 0 pairing. The competition between T = 0 and
T = 1 pairing channels substantially aﬀect the energy
minima of 24 Mg, 28 Si and 32 S. Our model gives a reasonable deformation minima for these nuclei, i.e., prolate for 24 Mg and 32 S and oblate for 28 Si.
References

1) H. Matsubara et. al., Phys. Rev. Lett. 115, 102501(2015).
2) A. Arima , K. Shimizu, W. Bentz, H. Hyuga, Adv. Nucl.
Phys. 18, 1 (1987).
3) I. S. Towner, Phys. Rep. 155, 263 (1987).
4) H. Sagawa, C. L. Bai, G. Colo, Phys. Scr. 91, 083011(2016).

Condensed from the article in Phys. Rev. C 97, 024320(2018)
Department of Physics and Origin of Matter and Evolutionof Galaxy (OMEG) Institute, Soongsil University
RIKEN Nishina Center
Center for Mathematics and Physics, University of Aizu

- 76 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Low-lying collective excited states in non-integrable pairing models
based on stationary phase approximation to the path integral †F. Ni,∗1 N. Hinohara,∗1,∗2 and T. Nakatsukasa∗1,∗2,∗3

†

∗1
∗2
∗3

Condensed from the article in Phy. Rev. C 98, 064327 (2018)
Faculty of Pure and Applied Sciences, University of Tsukuba
Center for Computational Sciences, University of Tsukuba
RIKEN Nishina Center- 77 -

80
B(Pad)The time-dependent mean-field (TDMF) theory isa standard theory to describe the dynamics of nuclei
from the microscopic degrees of freedom.1) Inclusionof the pairing dynamics leads to the time-dependent
Hartree-Fock-Bogoliubov (TDHFB) theory, which has
been utilized for a number of studies of nuclear reaction and structure. The small-amplitude approximation of TDHFB with modern energy density functionals, namely quasiparticle random phase approximation(QRPA), has successfully reproduced the properties ofgiant resonances in nuclei. In contrast, the QRPA description of low-lying quadrupole vibrations is not as
good as that of the giant resonances. A large-amplitude
nature of the quantum shape fluctuation is supposed to
be important for these low-lying collective states.
The TDMF (TDHFB) theory corresponds to an SPA
solution in the path integral formulation. It lacks apart of quantum fluctuation, which is important in large
amplitude dynamics. To introduce the quantum fluctuation based on the TDHFB theory, requantization isnecessary. A simple and straightforward way of requantization is canonical quantization. This is extensively
utilized for collective models in nuclear physics.
In our previous work,2) we studied various requantization methods for the two-level pair model, in order
to investigate the low-lying excited 0+ states. Since thecollectivity is rather low in the pairing motion in nuclei,
the canonical quantization often fails to produce an approximate answer to the exact solution. In contrast,
the stationary phase approximation (SPA) to the path
integral can give quantitative results not only for theexcitation energies but also for the wave functions andtwo-particle-transfer strengths. The quantized statesobtained in the SPA has two advantages: First, thewave functions are given directly in terms of the microscopic degrees of freedom. Second, the restorationof broken symmetries are automatic. However, the applications of SPA have been limited to integrable systems. This is because we need to find separable periodic trajectories on a classical torus. Since nuclear
systems, of course, correspond to non-integrable systems, a straightforward application of the SPA is notpossible.
In this paper, we propose a new approach of SPA
applicable to non-integrable systems, which is basedon the extraction of the one-dimensional (1D) collective coordinate using the adiabatic self-consistent col-

60
40
20
0

gs-->gs
02+-->02+
gs-->gs++
02 -->02] Exact] ASCC+SPA

188
190
192
Initial mass number of Pb

Fig. 1. Calculated two-neutron transfer matrix elements for
Pb isotopes.

lective coordinate (ASCC) method.1) Since the 1D system is integrable, the collective subspace can be quantized with the SPA. The optimal degree of freedom associated with a slow collective motion is determined
self-consistently inside the TDHFB space, without any
assumption. Thus, our approach of ASCC+SPA basically consists of two steps: (1) Find a decoupled 1D
collective coordinate of the collective motion of interest.
(2) Apply the SPA to the collective mode.
On the decoupled collective subspace, which is derived by the ASCC, we apply the Einstein-BrillouinKeller (EBK) quantization rule,
p1 dq 1 = 2πk,(1)Ckwhere k is an integer with a unit of h̄ = 1. Then, on
this trajectory Ck , the k-th stationary state is given as asuperposition of the (generalized) Slater determinants:ρ(q, p)dt |q, p⟩ eiT [q,p] ,(2)|ψk ⟩ =
Ck

where T [q, p] is the classical action integral. Thismethod is applied to the neutron pairing model for
Pb isotopes. We calculate the two-neutron-transfer
strengths from the ground to the ground and from theexcited to the excited states (Fig. 1). A reasonableagreement is found between the ASCC+SPA and theexact calculations.
References

1) T. Nakatsukasa, K. Matsuyanagi, M. Matsuo, K. Yabana, Rev. Mod. Phys. 88, 045004 (2016).
2) F. Ni, T. Nakatsukasa, Phys. Rev. C 97, 044310 (2018).

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Study of giant dipole resonance in hot rotating light mass nucleus 31 P†
D. Mondal,∗1 D. Pandit,∗1 S. Mukhopadhyay,∗1,2 S. Pal,∗1 S. Bhattacharya,∗3 A. De,∗4 N. D. Dang,∗5
N. Q. Hung,∗6 S. Bhattacharya,∗1,∗2 S. Bhattacharyya,∗1,∗2 B. Dey,∗7 P. Roy,∗1 K. Banerjee,∗1,∗2,∗8 and
S. R. Banerjee∗9
The Isovector Giant Dipole Resonance (GDR) is observed in all nuclei and is characterized by the resonanceenergy (EG ), width (ΓG ) and strength (SG ).1) Macroscopically, it is described as out-of-phase oscillation of
proton and neutron ﬂuids, while microscopically, it isa coherent excitations of one particle-one hole (1p-1h)
conﬁgurations across one major shell. It can be built
on the ground state as well as every excited states ofatomic nucleus. The GDR built on the nuclear excitedstates is experimentally studied by two complementary
methods, namely inelastic scattering reactions and fusion evaporation reactions.
In this report, a systematic study of the GDR parameters is presented in a very light mass nucleus 31 P
by using fusion evaporation reactions. The compound
nucleus (CN) 31 P was populated at three diﬀerent excitation energies by using the α beam (Ebeam = 28, 35,
42 MeV) from K-130 cyclotron at the Variable Energy
Cyclotron Centre, Kolkata. The GDR and nuclear level
density (NLD) parameters have been determined by simultaneous statistical model analysis of the high-energy
γ ray and neutron spectra measured with the LAMBDA
array2) and neutron time of ﬂight detectors,3) respectively. The angular momentum (J) of the multiplicities
with a multiplicity ﬁlter.4) The angular distribution of
the high-energy γ rays has been performed to determine the bremsstrahlung component which is observed
for the beam energies above ∼10 MeV/nucleon. The estimation of the bremsstrahlung contribution is crucial
for precise determination of the GDR parameters.
It was observed that the GDR remains very much collective in this light mass nucleus and the EG remains
roughly constant at around 17.5 MeV as the nuclear
temperature (T ) changes. In Fig. 1, the measured GDR
widths are compared with the results of calculations
within diﬀerent models and plotted as a function of T .
Panels (a) and (b) show that the thermal shape ﬂuctuation model (TSFM)5) and the phenomenological thermal shape ﬂuctuation model (pTSFM)6) (phenomenological version of TSFM) overpredict the measured
†

∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Condensed from the article in Phys. Lett. B 784, 423 (2018)
Variable Energy Cyclotron Centre
Homi Bhabha National InstituteDepartment of Physics, Barasat Govt. College
Department of Physics, Raniganj Girls’ College
RIKEN Nishina Center
Institute of Fundamental and Applied Sciences, Duy Tan
University
Saha Institute of Nuclear Physics
Department of Nuclear Physics, Australian National University(Ex) Variable Energy Cyclotron Centre- 78 -

Fig. 1. Comparison of measured GDR width with the results of various model calculations as a function of T at
J = 11.5 h̄ (black dot-dashed line) and J = 15.5 h̄ (bluesolid line). The red long-dashed lines in panels (c) and(d) are the predictions at J = 0 h̄.

widths. In panel (c) the calculations within the critical temperature included ﬂuctuation model (CTFM)7)
is presented. Within this model, the GDR width remains constant at the ground-state value up to a criticaltemperature due to the GDR induced ﬂuctuation andincreases thereafter. Interestingly, this model nicely reproduced the measured widths. The widths were also
described quite well [panel (d)] by the results of calculations based on microscopic phonon damping model(PDM),8) according to which the GDR width arises owing to the coupling of the GDR state with the noncollective p-h, p-p and h-h conﬁgurations. The thermal
paring gaps are found to vanish in the ranges of T and
J considered in this experiment, therefore, have no effect on the measured GDR width in this light mass
system. The present results establish the universalityof CTFM and PDM in describing the GDR width as afunction of temperature and angular momentum.
References

1) M. N. Harakeh, A. van der Would, Giant Resonances:
Fundamental high-Frequency mode of nuclear excitation(Clarendon Press, Oxford, 2001).
2) S. Mukhopadhayay, et al., Nucl. Instrum. Methods Phys.
Res. A 582, 603 (2007).
3) K. Banerjee, et al., Nucl. Instrum. Methods Phys. Res.
A 608, 440 (2009).
4) Deepak Pandit, et al., Nucl. Instrum. Methods Phys.
Res. A 624, 148 (2010).
5) Y. Alhassid, et al., Phys. Rev. Lett. 61, 1926 (1988).
6) Dimitri Kusnezov, et al., Phys. Rev. Lett. 81, 542 (1998).
7) Deepak Pandit, et al., Phys. Lett. B 713, 434 (2012).
8) N. Dinh Dang, et al., Phys. Rev. Lett. 80, 4145 (1998).

3. Nuclear Data

Ⅱ-3. Nuclear Data

RIKEN Accel. Prog. Rep. 52 (2019)

Verification test of 107 Pd transmutation†
Y. Miyake,∗1 N. Ikoma,∗1 K. Takahashi,∗1 Y. V. Sahoo,∗1 and H. Okuno∗1
In a previous study, we reported the construction of an
implantation beam line for 107 Pd transmutation.1) After
that, 107 Pd was implanted into a carbon foil and irradiated by a deuteron beam. In this study, a veriﬁcation
test for the 107 Pd transmutation is reported.
107
Pd ions were implanted into a carbon foil as
107
PdO− with an energy of 20 keV. This foil is a multilayer graphene sheet with a thickness of 360 µg/cm2 developed by KANEKA.2) The amount of implanted 107 Pd
was analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to be approximately 270 ng in a carbon foil. The 107 Pd-implanted sample was irradiated bydeuteron at 12 MeV/nucleon with a current of 1–2 particle µA. The cumulative irradiation current was 1.09 C,
which corresponds the irradiation with a beam currentof 1 particle µA for 12.6 days.
After cooliing, γ-ray measurements were conducted.
The γ-ray spectrum of the irradiated sample is shownin Fig. 1. γ-ray emitting from radionuclides of 7 Be,
105
Ag, and 106m Ag were detected. 7 Be is produced fromcarbon, while 105 Ag and 106m Ag are generated fromthe transmutation of 107 Pd. The activities of 105 Ag
and 106m Ag were calculated from the γ-ray spectrumof 345 keV and 450 keV, respectively. The activity wasdetermined using the total net count of γ-ray peaks. The
radioactivity was decay-corrected from the day when
the deuteron irradiation ﬁnished. Considering the γray abundance of 0.41 at 345 keV and 0.28 at 450 keV,
the activity was calculated to be 8.38 × 102 Bq and4.98 × 104 Bq, which correspond with 0.8 pg of 105 Ag
and 9.0 pg of 106m Ag, respectively.3)

Fig. 2. Isotopic ratio of Pd/107 Pd of irradiated sample.

The production yield of nuclides per deuteron was calculated using the Particle and Heavy Ion Transport code
System (PHITS) to estimate the amount of 105 Pd and106
Pd generated by the experiment.4) Assuming that all
105
Ag and 106m Ag detected by the γ-ray measurements
will be converted into 105 Pd and 106 Pd, respectively,
they amount to 92% for 105 Pd and 25% for 106 Pd generated from the 107 Pd transmutation. Therefore, the total
amount of 105 Pd and 106 Pd was estimated to be 0.9 pg
for 105 Pd and 40 pg for 106 Pd. Considering that theamount of implanted 107 Pd was estimated to be 270 ng,
the isotopic ratios were calculated to be 3.29 × 10−6 for105
Pd/107 Pd and 1.49 × 10−4 for 106 Pd/107 Pd.
The isotopic ratio normalized by the number of 107 Pd
nuclei (Pd/107 Pd) was also evaluated by a simulation
using PHITS. Considering the production yield of eachnuclide, the change in the isotopic ratios were estimatedto be 2.90 ×10−6 for 105 Pd/107 Pd and 8.43 × 10−5 for106
Pd/107 Pd for deuteron irradiation performed with abeam current of 1 particle µA for 12.6 d. This estimation is consistent with the experimental results, thereby
preliminarily verifying the 107 Pd transmutation (Fig. 2).
This work was funded by the ImPACT Program of theCouncil for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
References

Fig. 1. γ-ray spectrum of irradiated sample.
†∗1

Condensed from the article in Y. Miyake et al., OECD/NEA(2018) Proceedings of the Fifteens Information Exchange
Meetings on Actinide and Fission Product Partitioning andTransmutaiton, Manchester, UK, 1-3 October 2018.
RIKEN Nishina Center- 79 -

1) Y. Miyake et al., RIKEN Accel. Prog. Rep. 51, 102(2018).
2) A. Tatami et al., AIP Conference Proceedings, 1962,
030005 (2018).
3) R. L. Heath, Gamma-ray spectrum catalogue: Ge(Li) andSi(Li) spectrometry, Fourth edition, Aerojet Nuclear Co.,
Idaho Falls, Idaho (1974).
4) T. Saito et al., J. Nucl. Sci. Technol. 55, 684–690 (2018).

Ⅱ-3. Nuclear Data

RIKEN Accel. Prog. Rep. 52 (2019)

Measurement of neutron production
from 7 MeV/nucleon α incidence on a Bi target
K. Sugihara,∗1,∗2 E. Lee,∗1,∗2 N. Shigyo,∗1,∗2 K. Tanaka,∗1 A. Akashio,∗1 and T. Sanami∗1,∗3°

RF signal and the neutron detector. The TDC resolution was about 0.012 ns/ch. The peak at 3650 ch was
the prompt γ-ray from the α incident reactions. Lowenergy neutrons from the preceding beam bunch wereoverlapped in the TOF spectrum. These events were
excluded because their small signals were lower than thethreshold level of the electronics. The neutron eventswere extracted by using the diﬀerence in the decay partof the signal between neutrons and γ-rays.1)
The measured neutron TTY and the calculation results by INCL2) and JQMD3) models in PHITS4) code
are shown in Fig. 3. The results of INCL show better
agreement with the experimental results than those of
JQMD.
The measured data will be applied to the shielding
design of the new beam line.

Counts

102

10

1
0

500 1000 1500 2000 2500 3000 3500
TDC [ch]Fig. 2. TOF spectrum at 0◦ .

10 6
10

°

7

10 8
10

°

9

10 10

°
°

exp
INCL
JQMD

10 5
TTY [n/sr/MeV/source]

RIKEN has a plan of installing a new beam line for
producing 211 At by α particle incidence on a 209 Bi target. It is assumed that an α beam should have an energyof 7.16 MeV/nucleon to reduce undesired byproducts.
Validation of Monte Carlo simulation codes on radiation shielding is required for the design of a beam line.
The neutron energy spectrum of the 209 Bi(α, 2n)211 At
reaction has not been measured. Experimental data of
double-diﬀerential neutron thick target yields (TTY) aredesired as a neutron source term in the radiation shielding design. We measured the neutron energy spectra by
the time-of-ﬂight (TOF) method.
The experiment was carried out at the E7B course of
AVF cyclotron. The experimental arrangement is illustrated in Fig. 1.
The 7.16 MeV/nucleon α beam irradiated a 209 Bi target. The repetition rate of the beam was about 16 MHz.
The integrated beam current was obtained from thecounts of a neutron survey meter set near the target
chamber. The thickness of the target was 2 mm, which
was longer than the range of the α particle.
Neutrons from the target were measured with EJ301
liquid organic scintillators that were 2 inch in diameterand thickness. A 2 mm thick plastic scintillator was
set as a veto detector. The neutron kinetic energy wasdetermined by the TOF method in which the start andstop signals came from the neutron scintillator and theRF signal of the AVF cyclotron, respectively. The ﬂight
path lengths from the target to the detectors were from
1 to 1.2 m as shown in Fig. 1. The background neutrons
were estimated from the measurement data with an ironshadow bar of 60 cm thickness between the target andeach neutron detector.
Figure 2 shows the TOF spectrum at 0◦ . The horizontal axis represents the time diﬀerence between the

°

10 11

10 12
10 13
2

4
6
8 10 12 14
Neutron Energy [MeV]Fig. 3. Neutron TTY and the calculation results by INCL
and JQMD implemented in PHITS.
Fig. 1. Experimental arrangement.
∗1
∗2
∗3

References

RIKEN Nishina Center
Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University
KEK- 80 -

1) T. Nakamoto et al., J. Nucl. Sci. Technol. 32, 827 (1995).
2) A. Boudard et al., Phys. Rev. C 87, 014606 (2013).
3) K. Niita et al., Phys. Rev. C 52, 2620 (1995).
4) T. Sato et al., J. Nucl. Sci. Technol. 55 (2018).

Ⅱ-3. Nuclear Data

RIKEN Accel. Prog. Rep. 52 (2019)

EXFOR compilation of RIBF data in 2018
S. Jagjit,∗1 T. Tada,∗1 M. Aikawa,∗1,∗2 D. Ichinkhorloo,∗1 S. Imai,∗3 M. Kimura,∗1 and N. Otuka∗2,∗4
Table 1. Entry numbers with references compiled fromRIBF data in 2018.

Nuclear reaction data is the central cohesive sourceof support for the new advancements in nuclear technology (e.g., nuclear power, fuel cycles, environmental
monitoring, dosimetry, radiation safety, radioisotope
production, radiotherapy, and medical diagnostics)
and science (e.g., nuclear physics, nuclear chemistry,geophysics, and astrophysics). A nuclear databaseplays a vital role in providing the best estimated nuclear reaction data to a wide range of data users
working in various ﬁelds of science and related areas. One such database open to the public is the
EXchange FORmat (EXFOR) library for experimental nuclear reaction data.1) The EXFOR database is
the universally common repository for nuclear reactions, which was established in 1967, and is maintained by the International Network of Nuclear Reaction Data Centres (NRDC) under the auspices of theInternational Atomic Energy Agency (IAEA).2) The
scope of EXFOR covers a wide range of nuclear reactions such as neutron-induced, charged-particle, andphoton-induced reactions.
The Hokkaido University Nuclear Reaction Data
Centre (JCPRG)3) was founded in 1973 and has beena member of NRDC since 1975. JCPRG is responsible for the compilation of charged-particle and photoninduced nuclear reactions measured at the facilities located in Japan.4) The contribution of JCPRG to the
EXFOR database amounts to ∼ 5% of the total entries.
Our compilation process involves the scanning ofpeer-reviewed journals for the published papers thatmeet the scope of EXFOR. A unique entry number isassigned to each selected paper to be compiled for the
EXFOR library to track progress in compilation. The
compilers extract the bibliographic information, experimental set up, measured physical quantities, measured
numerical data, and error information that are given as
input to a single entry of EXFOR. During this process,we contact the corresponding authors for questions on
the content of the papers and requests for numericaldata.
JCPRG has cooperated with the RIKEN Nishina
Center for the compilation of data obtained in RIBF
since 2010. The purpose of this cooperation is to increase the availability of nuclear reaction data obtained
at RIBF. In this article, we report our activities related
to the RIBF data. In 2018, we compiled 53 new papers reporting the experiments performed at Japanese
∗1
∗2
∗3
∗4

Enteries

Total

E25165)
E25498)
E255711)
E257414)
E257817)

E25426)
E25539)E256112)
E257515)
E258018)14

E25437)
E255410)
E256213)
E257616)

facilities and out of these, 14 papers were based on
RIBF data. All authors of these 14 entries had kindly
provided us the numerical data. The compiled data isaccessible by the entry numbers listed in Table 1.
We have established an eﬀective procedure to compile all new publications during the last eight-year collaboration with the RIKEN Nishina Center. Therefore, most of the recent experimental nuclear reaction
data is provided by the corresponding authors. This
cooperation is valuable and eﬀective, and essential forcontinuing rapid and reliable compilation.
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, No. 5, 24 (2018).
5) S. Hayakawa et al., Phys. Rev. C 93, 065802 (2016).
6) D. Kaji et al., J. Phys. Soc. Jpn. 86, 085001 (2017).
7) J. W. Hwang et al., Phys. Lett. B 769, 503 (2017).
8) T. Sumikama et al., Phys. Rev. C 95, 051601 (2017).
9) S. Momiyama et al., Phys. Rev. C 96, 034328 (2017).
10) H. Suzuki et al., Phys. Rev. C 96, 034604 (2017).
11) V. Vaquero et al., Phys. Rev. Lett. 118, 202502 (2017).
12) N. Fukuda et al., J. Phys. Soc. Jpn. 87, 014202 (2018).
13) Y. Shimizu et al., J. Phys. Soc. Jpn. 87, 014203 (2018).
14) M. Aikawa et al., Nucl. Instrum. Methods Phys. Res.
B 426, 18 (2018).
15) N. Ukon et al., Nucl. Instrum. Methods Phys. Res. B
426, 13 (2018).
16) T. Nishi et al., Phys. Rev. Lett. 120, 152505 (2018).
17) M. Aikawa et al., Nucl. Instrum. Methods Phys. Res.
B 427, 91 (2018).
18) S. Chebotaryov et al., Prog. Theor. Exp. Phys. 2018,
053D01 (2018).

Faculty of Science, Hokkaido University
RIKEN Nishina Center
Institute for the Advancement of Higher Education,
Hokkaido University
NDS, IAEA- 81 -

4. Hadron Physics

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Preliminary result of the transverse single spin asymmetry in very
forward π 0 production in 510 GeV p↑ + p collisions
M. H. Kim∗1,∗2 for the RHICf collaboration
The RHICf experiment1) measured the transverse
single spin asymmetry, AN , which is deﬁned as the leftright cross section asymmetry of beam polarization, ofvery forward π 0 in June, 2017. The spin-related interactions between protons and the production mechanism of a particle can be deeply understood by ANmeasurement. To date, the non-zero AN of forward
π 0 has been measured by many experiments, and theparton-level interaction between protons has generally
been considered to be the origin of the π 0 production.
However, recently, larger AN was observed for more
diﬀractive-like events than the events driven by hard
scattering;2) therefore, the measurement of AN in very
forward π 0 production by the RHICf experiment will
provide a new input to unveil the origin of the non-zero
AN of π 0 , especially from the viewpoint of diﬀractive
and non-diﬀractive interactions.
To measure the very forward π 0 , we moved an electromagnetic calorimeter (RHICf detector), which was
originally developed for the LHCf experiment,3) from
CERN to BNL, and installed it at the zero-degree areaof the STAR experiment, which was 18 m away fromthe beam collision point. The RHICf detector consistsof two sampling calorimeters; smaller one has a lateraldimension of 20 mm × 20 mm and the larger one hasa lateral dimension of 40 mm × 40 mm. Each tower
is composed of 16 GSO plates for energy measurement
and 4 layers of GSO bars for position measurement. π 0
can be identiﬁed and reconstructed by measuring two
decayed photons with two towers or even one tower
because the position resolution for photons is of thelevel of a few hundred µm. We measured very forward
π 0 with a wide transverse momentum (pT ) coverageof 0 < pT < 1 GeV/c and a longitudinal momentum
fraction (xF ) range of 0.2 < xF < 1. For the correlation study with other STAR detectors, we took thedata using the STAR data acquisition system.
Experimentally, AN is calculated by following equation:
1 1 ( N ↑ − RN ↓ )
AN =
,
(1)
P Dϕ N ↑ + RN ↓

AN

0.3

0.25
0.2
0.15
0.1

∗1

p↑+p → π0+X at s = 510 GeV
6<η
0.2 < xF < 0.4
0.4 < xF < 0.6
0.6 < xF < 1.0

0.05
0
−0.05
−0.1
0

0.2

0.4

0.6

0.8
p (GeV/c)T

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

oﬀset angle. Typical values of P and Dϕ is around 0.6
and 0.96 respectively.
Figure 1 presents our ﬁrst result for the AN of very
forward inclusive π 0 production. Surprisingly, nonzero AN of π 0 was observed even in very forward π 0
production. AN increases as a function of both xF
and pT . Because the non-zero AN in Fig. 1 was driven
by the π 0 produced in the very forward region where
the diﬀractive process is dominant, the diﬀraction canbe considered to be a possible contributor of this ﬁnite AN as expected by a recent study.2) In order tofurther study the role of diﬀraction in the forward π 0
production, we are now analyzing the correlation between RHICf and STAR detectors. STAR forward detectors and Roman pot4) can identify diﬀractive events
by observing the rapidity gap or a recoil proton. Therefore, we will be able to understand the relation between
diﬀraction and AN of (very) forward π 0 with a combined RHICf-STAR analysis.

where N ↑(↓) is the number of detected π 0 in p↑(↓) + p
collision and R is the luminosity ratio between two
collision types of spin up (↑) and down (↓). P represents the average polarization of the proton beam andDϕ is a correction factor for π 0 azimuthal angle distribution because AN usually depends on the particle’s
azimuthal angle by AN ∝ sin(ϕ − ϕ0 ) where ϕ0 is an∗2

RHICf Preliminary

References
1) RHICf Collaboration, LOI, arXiv: 1409.4860v1.
2) S. Heppelmann (STAR Collaboration), Proc. Sci.
DIS2013, 240 (2013).
3) O. Adriani et al. (LHCf Collaboration), J. Instrum. 3,
S08006 (2008).
4) S. Bültmann et al., Nucl. Instrum. Methods Phys. Res.
A 535, 415 (2004).

RIKEN Nishina Center
Department of Physics, Korea University- 83 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

The stability of energy scale for RHICf photon measurement during the2017 operation√
Mγγ = θ Eγ1 Eγ2 ,(1)where θ is the opening angle of a photon pair, and Eγ1
and Eγ2 are the photon energies. Figure 1 shows the reconstucted mass distribution of photon pair events obtained in RHICf-Run 2625, which contains 3.5 × 104
events. The peak in the distribution corresponds tothe π 0 events. The distribution is fit with the Gaussian function combined with the Chebyshev polynomial
function for the background event. The variation of
the invariant-mass peak measured in each RHICf-run isshown in Fig. 2. The horizontal and vertical axes show
the run number of the RHICf experiment and the relative peak position of the invariant mass measured ineach run to the one in Run 2625, respectively. The red
dotted lines show the variations at −1.5% and +1.5%.
From the result, we conclude that the energy scale ofthe calorimeters was stable within ±1.5%, which is lessthan the uncertainty of the absolute energy scale estimated from the beam test. The small variation may be
due to the temperature dependency of the PMTs used in
the detector. The detailed investigation is in progress.
∗1∗2

RIKEN Nishina Center
Institute for Space-Earth Environmental Research, Nagoya
University- 84 -

3000

2500

RHICf Preliminary

RHIC Run17 510GeV p+p
RHICf Run2625
Type-I π0

2000

Data

1500

Fit result

1000

500

0

0

20

40

60

80

100 120 140 160 180 200
Mgg [MeV]

Fig. 1. The invariant mass distribution of photon pair events.
Red line shows the composite function of the Gaussianfunction and the Chebyshev polynomial function.
The relative peak positon of π 0 mass

The RHIC forward (RHICf) experiment1) aims to verify hadronic interaction models2–4) by measuring the
production cross-sections of forward neutral particles(photons, neutrons, and π 0 ) emitted during protonproton√ collisions with a center-of-mass collision energyof s = 510 GeV at BNL-RHIC, which is important tounderstand the development of air showers for cosmicray physics. The RHICf operation was successfully completed in 2017.
The RHICf detector is located 18 m from the interaction point where the STAR detector is installed. The
RHICf detector has two compact sampling and positioning calorimeters. Each calorimeter is composed of 16 layers of GSO scintillators, 4 X-Y hodoscope layers of GSO
bar bundles, and tungsten absorber layers. The energyof an incident photon is reconstructed from the summation of the energy deposits in the scintillator layers. Theenergy calibration of the calorimeters was performed using 50–200 GeV/c electron beams at CERN-SPS before
the operation at RHIC, and the systematic uncertainty
was found to be about 3%.5)
The energy scale can be verified and monitored using
π 0 events recorded in the proton-proton collision data.
The π 0 events are identified by measuring the photon
pairs produced from π 0 decays. The invariant mass of aphoton pair, Mγγ , is calculated as

Events(/bin)

K. Sato∗1,∗2 and H. Menjo∗1,∗2 for the RHICf collaboration

1.03

RHICf Preliminary

1.02

RHIC Run17 510GeV p+p
Type-I π0 sample+1.5 %

1.01

1

0.99

-1.5 %

0.98

0.97
2600

2650

2700

2750

2800

2850

2900

2950

3000

Run number

Fig. 2. The relative peak position of the reconstructed π 0mass in each run, which is comapared with the one in
RHICf-Run 2625. The red dotted lines show ±1.5%. The
lower arrows indicate the physics operation periods withcollisions.

References

1) RHICf Collaboration, Letter of Intent, arXiv:1401.1004;
RHICf proposal, arXiv:1409.4860.
2) T. Pierog, Iu. Karpenko, J. M. Katzy, E. Yatsenko,
K. Werner, Phys. Rev. C 92, 034906 (2015).
3) S. Ostapchenko, Phys. Rev. D 83, 014018 (2011).
4) E. -J. Ahn, R. Engel, T. K. Gaisser, P. Lipari, T. Stanev,
Phys. Rev. D 80, 094003 (2009).
5) Y. Makino et al., J. Instrum 12, P03023 (2017).

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Cross section and longitudinal single-spin asymmetry AL for forward
W ± → µ± ν production in polarized p + p collisions√
at s = 510 GeV†

Sampled range

σ(pp→W±)× BR(W→ l±) total cross section
W-

W

RHICBOS+PYTHIA
CHE
STAR W→ e
PRD85 (2012) 092010
PHENIX W→ e
PRL 106 (2011) 062001-1.0 < η < 1.0-0.35 < η < 0.35

PHENIX W→ µ2013 :∫ Ldt = 285 pb-1

1.1 < |η| < 2.5
50

100

150

200

250

300

σ(pp→W± )× BR(W→ l± ) [pb]Fig. 1. The W ± → µ± ν cross section measured at forward
and backward rapidity 1.1 < |η| < 2.5 (closed [blue] circles) and previously published results at central rapidity.
†

∗1

1.0

(a)

W++Z→µ+,e+µ

AL (2012)µAL (2013)
PHENIX AeL (2011-2012), pe > 30 GeV
T
PHENIX AeL (2013), pe > 30 GeV

p+p at s = 510 GeV

0.5

T

0.0
-0.5

AL

Understanding the spin of the proton and its decomposition is essential to explaining how the strong interaction, described by quantum chromodynamics QCD,
creates the basic building blocks of the visible matterin our universe, protons and neutrons. Sea quarks arefound to be asymmetric at small to intermediate Bjorken
x < 0.2, where x is the parton momentum fraction.
While several models can describe the measured unpolarized light sea, these models diﬀer signiﬁcantly in theirpredictions for the polarized case. Valence quark helicity contributions to the total spin of the nucleon are
already relatively well known, but sea quark helicities
are still poorly understood. An elegant way to accesssea quark helicities is via the weak interaction as possible at the Relativistic Heavy Ion Collider (RHIC).1) In
p + p collisions, real W ’s can be produced in the annihilation of predominantly up(down) and anti-down(up)quark pairs for W +(−) production. Furthermore, thehelicity of participating quarks and anti-quarks is ﬁxed
to be left-handed and right-handed, respectively, due tothe parity violating nature of the weak interaction. If
one of the two proton beams is longitudinally polarized,
the helicity of the proton beam therefore selects quarks
that are polarized parallel or anti-parallel with it andvice versa for anti-quarks.
In this analysis, we rely on the reconstruction of
forward-going muons impinging the muon-spectrometerof the PHENIX detector. The data sets used in this analysis were recorded at RHIC during the 2012 and 2013
polarized√ proton running periods at a center-of-mass energy s = 510 GeV with a luminosity of approximately

AL

R. Seidl∗1 for the PHENIX collaboration

-1.0
1.0

(b)

W-+Z→µ-,e-STAR AeL(PRL 113 (2014) 072301)
DSSV ET>25 GeV

0.5
0.0
NNPDFpol1.1
GRSV STDDSSVDNS KKP
DNS Kretzer

-0.5
-1.0

-2

-1

DSSV 0.6

DSSV 0.5

0

1

2

η

l

Fig. 2. Longitudinal single spin asymmetry, AL for (a)W + + Z→µ+ , e+ and (b) W − + Z→µ− , e− for PHENIX
for 2012 (closed [blue] circles) and 2013 (closed [purple]
circles) and previously published data and parameterizations.

53 and 285 pb −1 . The average beam polarizations were
between 54% and 58% for the two beams and running
periods. For each event a combined probability distribution, Wness is formed from all variables. Tracks withhigh Wness (> 0.92) are used for further analysis. An
unbinned maximum likelihood ﬁt approach is used todetermine the ﬁnal number of W s and remaining backgrounds. Figure 1 shows the extracted total cross sections for inclusive W ± → µ± production in p + p collisions at a center-of-mass energy of 510 GeV. The crosssections are consistent within uncertainties with previous measurements at this energy from central W → e
decay channels and with the expected NLO predictions.
The longitudinal single-spin asymmetries, AL are shownin Fig. 2 for positive and negative W + Z decay muoncandidates. They show the ﬁrst muon single spin asymmetry results from W + Z decays at pseudorapidities|η| > 1 of the decay lepton. They help determine thevalence and sea quark helicities at diﬀerent momentum
fractions than at central rapidities. The behavior of theasymmetries is generally consistent with the parameterizations.
Reference

1) C. Bourrely and J. Soﬀer, Phys. Lett. B 314, 132 (1993).

Condensed from the article Phys. Rev. D 98, 032007 (2018)
RIKEN Nishina Center- 85 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Progress in analysis technique for extracting light-antiquark flavor
asymmetry by SeaQuest at Fermilab
K. Nagai,∗1 Y. Goto,∗2 Y. Miyachi,∗3 K. Nakano,∗2,∗4 S. Sawada,∗2,∗5 T. -A. Shibata,∗2,∗6 for theE906/SeaQuest Collaboration
The amounts of d¯ and ū in a proton were expected tobe the same based on the ﬂavor independence of gluon
splitting. However, the NMC experiment at CERN
showed that the total amount of d¯ exceeds that of ū.1,2)
The NA51 experiment at CERN and the E866 experiment at Fermilab measured the Bjorken x dependence¯ 3,4) whereof the light-antiquark ﬂavor asymmetry d/ū,
Bjorken x is the momentum fraction of a parton to a
¯ > 1.0 at x < 0.25 andproton. They found that d/ū¯
d/ū < 1.0 at x ∼ 0.3, although the results at x ∼ 0.3
is consistent with 1.0 due to the large statistical un¯ in thiscertainty. It is very important to measure d/ū
unclear region in order to understand the proton structure.
The SeaQuest experiment is a Drell–Yan experiment
performed at the Fermi National Accelerator Laboratory (Fermilab) in Illinois, US. The main purpose ofthis experiment is to measure the light-antiquark ﬂavor asymmetry in a proton in 0.1 < x < 0.45, which includes the unclear region in the previous experiments.
As shown in Fig. 1, the Drell–Yan process is a reaction in which an antiquark in a hadron and a quark inanother hadron annihilate and decay into a lepton pair
via a virtual photon: q + q̄ → γ ∗ → µ+ + µ− .5) The
cross section of the proton-proton Drell–Yan process
at the leading order is expressed as
d2 σ
4πα2
=
dx1 dx2
9x1 x2

1s∑Fig. 1. Diagram of the Drell–Yan process.

took the physics data from 2013 through 2017. The
recorded number of beam protons on targets is 1.4 ×
1018 . At this moment, about 40% of the data are being
analyzed.
The preliminary result of the light-quark ﬂavor
asymmetry was reported.7) The analysis toward theﬁnal result is currently in progress.
There are two diﬃculties that need to be resolvedin the current analysis: the estimation of the beamintensity dependence of the reconstruction eﬃciency
and that of the random background. We are now testing a new method for resolving them based on real data
instead of simulation, namely the so-called extrapolation method.
In this method, we evaluate the cross section ratio
ﬁrst as a function of the beam intensity. Here, we do
not apply any corrections. Then it is ﬁtted with afunction and extrapolated to the zero beam intensity.
The extrapolated value is considered to be the “correct” cross section ratio. Through the simulation, we
conﬁrmed that the extrapolation method removes thebeam-intensity dependence of the reconstruction eﬃciency correctly. The investigation to conﬁrm whether
this method can handle the random background is inprogress.

e2i

i=u,d,s,...

[qi (x1 )q¯i (x2 ) + q¯i (x1 )qi (x2 )] , (1)where x is the Bjorken x, the subscripts (1, 2) denotethe beam and the target, respectively, and q(x) is theparton distribution function. In the SeaQuest acceptance (x1 ≫ x2 ), the last term of Eq. (1) vanishes
because the PDFs of antiquarks are small enough at
the high x region. Therefore, an antiquark of the target proton is always involved in the process and is thus
accessible easily.
The SeaQuest experiment measures the muon pairs
in the ﬁnal state of the Drell–Yan process, which is produced with the 120 GeV proton beam provided by the
Fermilab Main Injector and the liquid hydrogen anddeuterium targets. The details of the SeaQuest spectrometer have been reported in the past.6) SeaQuest
∗1
∗2
∗3
∗4
∗5
∗6

References
1) P. Amaudruz et al., Phys. Rev. Lett. 66, 2712 (1991).
2) M. Arneodo et al., Phys. Rev. D 50, R1 (1994).
3) A. Baldit et al., Phys. Lett. B 332, 244 (1994).
4) E. A. Hawker et al., Phys. Rev. Lett. 80, 3715 (1998).
5) S. D. Drell, T. M. Yan, Phys. Rev. Lett. 25, 316 (1970).
6) K. Nagai et al., RIKEN Accel. Prog. Rep. 49, 114(2016).
7) K. Nakano et al., RIKEN Accel. Prog. Rep. 50, 118(2017).

Institute of Physics, Academia Sinica, Taiwan
RIKEN Nishina Center
Department of Physics, Yamagata University
Department of Physics, Tokyo Institute of Technology
Institute of Particle and Nuclear Studies, KEK
College of Science and Technology, Nihon University- 86 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Forward hadron calorimeter R&D
Y. Goto,∗1 H. Matsuda,∗2 Y. Miyachi,∗3 I. Nakagawa,∗1 K. Nakano,∗1,∗4 R. Seidl,∗1 T. -A. Shibata,∗1,∗4,∗5
K. Tanida,∗1,∗6 and Y. Yamazaki∗7
High energy polarized proton collision experiments
at RHIC in Brookhaven National Laboratory haveshown that the perturbative QCD describes experimental data accurately, and have largely developed anunderstanding of the internal structure of the proton.
We will reﬁne it much further and explore how theproperties of the proton emerge from internal quarkand gluon interactions by measuring the 3D structureof the proton with high precision measurements in thesPHENIX experiment at RHIC and the Electron-Ion
Collider (EIC) in the future. The 3D understanding of
the proton structure will enable us to understand theorigin of the proton spin including the orbital motionof quarks and gluons (or collectively called partons).
We have proposed to construct a forward apparatusof the sPHENIX detector that will expand the kinematic coverage of the measurements of the 3D structure of the proton.1) In the forward rapidity region, alarge single-spin asymmetry (SSA) or azimuthal modulation is known to exist, which will enable us to study
the orbital motion of quarks and gluons. Theoretically, this phenomenon has been explained by thetransverse-momentum dependent parton distributionfunction and correlations of partons in the proton.
Based on these theoretical framework, we measure the
SSAs of forward jets, hadrons, electrons, photons, etc.
systematically in polarized proton collisions with highprecision at sPHENIX.
The forward hadron calorimeter is essential for theforward jet reconstruction and hadron energy measurements, along with triggering. Designing and developing this calorimeter is a joint project with the EIC
generic detector R&D group eRD1 and the STAR upgrade project.2) In addition to being a viable sPHENIX
forward calorimeter, the system is designed to fulﬁll
the requirements of a forward hadron calorimeter of
an EIC detector.
The forward hadron calorimeter is located outside
the ﬂux return yoke of the superconducting solenoid
magnet of the sPHENIX barrel detector system, witha front face 3.5 m away from the interaction point. The
presence of the ﬂux return yoke only has a minor eﬀect
on the calorimeter performance. The forward hadroncalorimeter consists of 2,044 towers measuring 10 cm ×10 cm × 81 cm with an expected energy resolution of

∗1

∗2
∗3
∗4
∗5
∗6
∗7

Fig. 1. An image of a tower of the hadron calorimeter.

√
approximately 70%/ E(GeV) for single hadrons. It
covers a pseudorapidity range of 1.2 < η < 4.0.
The design of the calorimeter follows the design of
the STAR upgrade project. A prototype calorimeter
tower has been made by STAR and it has been tested
at the FNAL test beam facility to validate the construction technique. It is scalable and re-conﬁgurablewith a minimal number of mechanical components.
Therefore, it minimizes the resources required for construction and operation. Figure 1 shows an image ofthe prototype calorimeter tower. It consists of 38 layersof 20 mm iron absorbers and 3 mm plastic scintillator
plates, which correspond to a total depth of approximately 4.5 nuclear interaction lengths. A wavelengthshifting (WLS) plate provides uniform and eﬃcient
light collection from all scintillation tiles along thedepth of the tower. The light from the WLS plate ismeasured with SiPMs similar to the sPHENIX barrel
calorimeters. This allows for the use of common readout electronics for all sPHENIX calorimeter systems.
Factors that limit the energy resolution are alignment
and non-uniformity.
References
1) E. C. Aschenauer et al., arXiv:1602.03922 [nucl-ex].
2) O. D. Tsai et al., J. Phys. Conf. Ser. 587, no. 1, 012053(2015).

RIKEN Nishina Center
J-PARC Center, Japan Atomic Energy Agency
Department of Physics, Yamagata University
Department of Physics, Tokyo Institute of Technology
College of Science and Technology, Nihon University
Advanced Science Research Center, Japan Atomic Energy
AgencyGraduate School of Science, Kobe University- 87 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Development of the intermediate silicon tracker for sPHENIX
experiment at RHIC
I. Nakagawa,∗1 Y. Akiba,∗1 H. Aso,∗1,∗2 D. Cacace,∗3 E. Desmond,∗3 T. Hachiya,∗1,∗4 T. Ichino,∗1,∗2
M. Isshiki,∗4 T. Kondo,∗5 H. Kureha,∗4 E. Mannel,∗3 G. Mitsuka,∗1 R. Nouicer,∗3 R. Pisani,∗3 K. Sugino,∗4
A. Suzuki,∗4 M. Tsuruta,∗1 T. Todoroki,∗1 and Y. Yamaguchi∗1

The development of the next generation experiment,
called sPHENIX,1) at RHIC has been ﬁrmly proceeded
and have passed the critical decision 1 and 3a approvalin August 2018. The R&D of the intermediate silicon
tracker for sPHENIX is almost in the ﬁnal stage of thedevelopment. The silicon strip sensor design and thehigh density interconnect (HDI)2) had been ﬁnalized
by the 2nd generation prototyping in early 2018. The
3 layers of INTT telescope ladder modules based onthese 2nd generation prototypes were assembled for the
beam test at Fermi Laboratory. Shown in the Fig. 1
is the telescope array used for the beam test in March2018.
The resulting spectra of the 120 GeV primary proton beam measured by a corresponding cell of eachladder layer are shown in Fig. 2. The observed position and the width of the Gaussian shapes are wellconsistent between the three layers and matches withthe expected beam proﬁle which is also measured by
the beam proﬁle monitor originally implemented at thetest beam facility of Fermi Lab. The noise performance
was also quite satisfactory.
The next round beam tests is scheduled in May, 2019with a full readout chain including a 1.2 meter bus extender3,4) and the air cooling stave support structure,
which were substituted by temporary solutions in thelast beam test because they were still in the middle ofdevelopment stages and not ready for the beam test.
The stave (Fig. 3 is the support structure of the INTT
module which consisted of silicon sensors and HDI as 

Fig. 2. The telescope of the INTT half ladder detectors
assembled for the beam test at Fermi Lab.

Fig. 3. The auto-CAD drawing of the stave support structure with the air cooling tubes.

Fig. 4. The HDI module mounted on the prototype stave.

Fig. 1. The telescope of the INTT half ladder detectors
assembled for the beam test at Fermi Lab.

shown in the Fig. 4. It requires not only the stiﬀness,but also high thermal conductivity in order to remove
heat generated from the read out chips mounted on
the HDI. The stave is made of a carbon ﬁber reinforced plastic (CFRP) and its prototyping has beenin progress both in Asuka Co. in Japan and Lawrence
Berkley National Laboratory in parallel. As well as themeasurement of thermal conductivity performance ofthe prototype staves, the stiﬀness is also tested before
the ﬁnalization.

∗1

References

∗2
∗3
∗4
∗5

RIKEN Nishina Center
Department of Physics, Rikkyo University
Brookhaven National Laboratory
Nara Women’s University
Tokyo Metropolitan Industrial Technology Research Institute1) Conceptual Design Report of sPHENIX (2018).
2) I. Nakagawa, RIKEN Accel. Prog. Rep. 50, (2017).
3) T. Hachiya et al., in this report.
4) M. Tsuruta et al., in this report.

- 88 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Tracking performance simulation for INTT at sPHENIX

Fig. 1. (Left) In-time vertex tagging and (Right) out-of-timevertex tagging eﬃciency versus event multiplicity.
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Department of Physics, Rikkyo University
Brookhaven National Laboratory
Nara Women’s University
Tokyo Metropolitan Industrial Technology Research Institute- 89 -sPHENIX Simulation

107

10 MHz p+p, 2 INTT layers
|Z

106

RECO

|<10cm, |η|<1.0

In time, Gen
RECO

105

In time, Reco (N≥20)
TPC
Pile-up, Gen

104

Pile-up, Reco (N≥20 && NINTT ≥1)

4

7

RECO
TPC

RECO

103
102
10
1
0

1

2

3

5

6

8

9

10

p (GeV/c)T

Fig. 2. Number of tracks from in-time and pile-up events asa function of pT with diﬀerent tracking requirements.
MVTX cluster association efficiency

The sPHENIX tracking system comprises, from theinside to outside, i) the Monolithic-Active-Pixel-Sensorbased Vertex Detector (MVTX),1) ii) the Intermediate
Silicon Strip Tracker (INTT),2) and iii) the Time Projection Chamber (TPC).2) MVTX measures the distance of
closest approach for heavy-ﬂavour physics. TPC aims at
a momentum resolution of 1.2% for diﬀerent Υ state separations. INTT has a narrow timing window of 100 ns,
which is orders smaller than those of MVTX (4000 ns)
and TPC (26400 ns), which provides rejection powers on
pile-up events and tracks.
The INTT tracking performance and its optimal layer
conﬁguration are evaluated via 1) pile-up event rejections, 2) pile-up track rejections, and 3) MVTX cluster association eﬃciency to TPC track seeds. For
these studies,√ Geant4 simulations with PYTHIA8 p+p
events at s = 200 GeV, embedded at realistic collision rates at sPHENIX, are employed. Tracks are reconstructed only with MVTX hit triplets and a cluster
in one of the INTT layers for the (1), while tracks areseeded in TPC and interpolated to INTT and MVTX
hits with the Hough transformation for the (2) and (3).
Figure 1 Left (Right) shows the event vertex tagging(rejection) eﬃciency in (out of) the INTT time window
as a function of PYTHIA event multiplicity at the collision rate of 12 MHz. The integrated in-time vertex
tagging eﬃciency is 98.4 ± 0.3%, and the integrated outof-time, i.e. pile-up, vertex rejection eﬃciency is 99%.
This indicates 1 INTT cluster provides a good rejectionof pile-up tracks.
Figure 2 shows the numbers of tracks per pT bin widthfrom in-time and pile-up events as a function of pT at
the collision rate of 10 MHz. The blue and red lines
are the generated tracks in in-time and pile-up events.

NRECO TRK / 0.5 GeV/c

T. Todoroki,∗1 Y. Akiba,∗1 H. Aso,∗1,∗2 D. Cacace,∗3 E. Desmond,∗3 T. Hachiya,∗1,∗4 T. Ichino,∗1 M. Isshiki,∗4
T. Kondo,∗5 H. Kureha,∗4 E. Mannel,∗3 G. Mitsuka,∗1 I. Nakagawa,∗1 R. Nouicer,∗3 R. Pisani,∗3 K. Sugino,∗4
A. Suzuki,∗4 M. Tsuruta,∗1 and Y. Yamaguchi∗1

1
0.8
0.6

+/- 5 µs MVTX timing window
RECO

NMVTX CLUS≥2

0.4

No pileup

10 MHz p+p345p (GeV/c)2INTT Layers
1INTT Layer

0.2

0INTT Layer

0
0

1

2

T

Fig. 3. MVTX cluster association eﬃciency to TPC track
seeds as a function of pT with diﬀerent number of INTT
layers.

The red circles show that the pile-up contribution in thereconstructed tracks becomes two orders smaller thanthat from the in-time events (blue squares) by requiring
1 INTT cluster in addition to 20 TPC clusters in tracking. This also indicates 1 INTT cluster provides a good
rejection of pile-up tracks.
Figure 3 shows MVTX cluster association eﬃciency
to TPC track seeds as a function of pT at no pile-up(0 Hz) and 10 MHz collision rates. The worst eﬃciency
is obtained without INTT (0INTT Layer) because of
the large distance between MVTX and TPC. INTT hits
in the association reduce the uncertainty in searching
MVTX hits, resulting in better eﬃciency. The eﬃciency
is the best with 2 INTT layers. These studies show thata two-layer INTT detector is optimal for obtaining thebest tracking performance at sPHENIX.
References

1) MVTX proposal submitted to the DOE Oﬃce of Science2) sPHENIX proposal, arXiv:1501.06197

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Preparation status of the J-PARC E16 experiment in 2018
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 JPARC Hadron Experimental Facility. Scientiﬁc (“stage1”) approval was granted to the experiment E16 by
PAC in March 2007. For the full (“stage-2”) approval,
the demonstration of experimental feasibility and theprospects of acquiring suﬃcient funds and beam-line
construction are necessary. Therefore a technical design report was submitted to PAC in May 2014, which
was revised twice according to the requirements of PAC.
The most recent revision was submitted to PAC in Jan.
2017.
In the PAC held in Jul. 2017, stage-2 approval forthe 40 shifts (320 hours) of a commissioning run was
granted. In this run, the background measurement
at the new beamline should be performed. The highmomentum beam line, where the experiment will be
conducted is being constructed by KEK. As of Jan.
2019, the target date of the ﬁrst beam and our commissioning run is between Jan. and Apr. in 2020, dependingon the budgetary status of KEK.
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 modiﬁcation the sizeof matter and meson momentum. The e+ e− decays ofthe ρ, ω, and J/ψ mesons can be measured simultaneously. Their yields depend on the trigger condition
required to suppress the background e+ e− pairs.
In order to increase the statistics by a factor of 100,
we plan to use a 30-GeV primary proton beam withan intensity of 1 × 1010 protons per beam pulse of 2sec duration and 5.52-sec cycle, in the high-momentum
beam line. We also use 0.2%-interaction targets that
produce an interaction rate of 10 MHz at the targets.
Our spectrometer has 26 modules. Owing to budget limitations, our ﬁrst goal of the staged construction plan is to construct eight modules, which approximately covers one third of the full acceptance. With theeight-module conﬁguration, we proposed Run-1 with
160 shifts (1280 hours) of physics run after the commissioning run. In the Run-1, we will be able to accumulate the statistics as six times as that of E325 andobtain the velocity dependence of spectral modiﬁcationin the Cu target, as shown in Fig. 1.
∗1

RIKEN Nishina Center- 90 -

Fig. 1. Expected signal of the spectral modification of ϕ inRun-1. As the measure of the modification, the ratioof excess amount to the amount of mesons in ϕ-peak is
examined and plotted as a function of βγ of the mesons.

The development of detectors and front-end modules
has been completed. We have proceeded the productionof detectors such as GEM Tracker (GTR) for tracking,3)Hadron Blind Čerenkov detector (HBD),4) and LeadGlass calorimeter (LG) for electron identiﬁcation. We
joined the RD515) collaboration in CERN that aims todevelop multi-pixel gas detectors including GEM. We
use SRS, which is a readout-system developed by RD51,
for GEM readout. For LG readout, a front-end module that uses the DRS4 chip6) has been developed byourselves.
The development of trigger electronics is still underway.7) Test of the amp-shaper-discriminator boards togenerate the trigger signal at GTR and HBD are in
progress toward the production planned in Apr. 2019.
The ﬁrmwares on the trigger logic and distribution
modules are also under construction toward the integrated test planned in May 2019.
References

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. Morino et al., JPS Conf.
Proc. 8, 022009 (2015). Y. Komatsu et al., JPS Conf.
Proc. 12, 020005 (2017).
2) R. Muto et al., Phys. Rev. Lett. 98, 042501 (2007).
3) W. Nakai et al., RIKEN Accel. Prog. Rep. 49, 195 (2015).
4) K. Kanno et al., Nucl. Instrum. Methods Phys. Res. A
819, 20 (2016).
5) http://rd51-public.web.cern.ch/RD51-Public/ .
6) https://www.psi.ch/drs/drs-chip/ .
7) T. N. Takahashi et al., J. Phys. Conf. Ser. 664, 082053(2015).

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Spectroscopy of pionic atoms in 122 Sn(d, 3 He) reaction and angulardependence of the formation cross sections†T. Nishi,∗1,∗2 K. Itahashi,∗2 G. P. A. Berg,∗3 H. Fujioka,∗4 N. Fukuda,∗2 N. Fukunishi,∗2 H. Geissel,∗5
R. S. Hayano,∗1 S. Hirenzaki,∗6 K. Ichikawa,∗1 N. Ikeno,∗7 N. Inabe,∗2 S. Itoh,∗1 M. Iwasaki,∗2 D. Kameda,∗2
S. Kawase,∗8 T. Kubo,∗2 K. Kusaka,∗2 H. Matsubara,∗8 S. Michimasa,∗8 K. Miki,∗1 G. Mishima,∗1 H. Miya,∗2
H. Nagahiro,∗6 M. Nakamura,∗2 S. Noji,∗1 K. Okochi,∗1 S. Ota,∗8 N. Sakamoto,∗2 K. Suzuki,∗9 H. Takeda,∗2
Y. K. Tanaka,∗1 K. Todoroki,∗1 K. Tsukada,∗2 T. Uesaka,∗2 Y. N. Watanabe,∗1 H. Weick,∗5 H. Yamakami,∗4
and K. Yoshida∗2(piAF Collaboration)
The central peak is assigned mainly to formation of
the 2p pionic state. The right most peak in the largermass side is contributed from higher pionic orbitals.
The pionic states in 121 Sn are observed for the firsttime. We made an elaborate fitting of the observed
spectrum and deduced the 1s and 2p binding energies
and the 1s width. The deduced binding energies andthe width agree with theoretical calculations.
In the measurement, a large angular acceptance of
BigRIPS provided a very unique opportunity. As
shown in Fig. 2 of Ref. 2), we observe reaction-angle dependence of the pionic atom formation spectra for the
first time. The dependence of both 1s and 2p states are
determined experimentally. Comparing the measured
dependence with a theoretical prediction,3) they are
qualitatively agreeing well, and the observed dependence directly confirms the assignment of the angularmomenta of the structures in the spectrum.
Quantitatively comparing the measured absoluteformation cross sections with the theoretical predictions, we find that the measured 2p cross section fairly
well agrees with the theory and that the 1s cross section is smaller by a factor of about 20%. Since a ratioof the measured cross sections of the 1s to 2p state is
attributed with relatively small errors, the deviationfrom the theory invokes important questions in understanding of the pionic atom formation reactions.
In conclusion, we conducted first pionic atom spectroscopy at RIBF and measured pionic 121 Sn as peakstructures in the missing-mass spectrum for the firsttime. Reaction angle dependence of the pionic 1s and
2p formation cross sections are observed and comparedwith theoretical calculations. The measured dependence qualitatively agree with the theory confirming
the correct assignment of the observed structures inthe spectrum. Measured absolute 2p cross section wellagrees with the theory but the theory overestimatesthe 1s cross section by a factor of about 5. The measurement firmly proves potential of the RIBF for futurehigh precision spectroscopy of pionic atoms.

Spectroscopy of deeply bound pionic atoms has been
contributing to understanding of non-perturbative lowenergy region of the QCD.1) We have started an experimental spectroscopy of pionic atoms at RIBF andconducted our first experiment in 2010 by measuring122
Sn(d, 3 He) reactions near the π − emission threshold for about 15h. We employed deuteron beam withthe energy of 498.9 ± 0.2 MeV and a typical intensity of 2 × 1011 /s accelerated by SRC. Such a highintensity deuteron beam may serve as an irreplaceablebasis for high statistical and systematic precision in
the spectroscopy and let us achieve opportunities toreach understanding of the the low-energy QCD with
unprecedented accuracy.
During the experiment, the deuteron beam impinged
on a thin 122 Sn target located at a nominal target position of BigRIPS. We used BigRIPS as a spectrometer
to momentum-analyze the emitted 3 He and measured
the Q-value of the reaction in the missing-mass measurement. We reconstructed the tracks of the 3 He by aset of tracking detectors placed near the F5 dispersive
focal plane. We installed a set of scintillation counters
at F5 and F7 focal planes and identified the particles.
After applying detailed optical aberration corrections,
we achieved excitation spectra of the target Sn nucleus with the best resolution of 0.42 MeV (FWHM).
The absolute excitation energy is calibrated by usinga polyethylene target to observe two-body reactions ofH(d, 3 He)π 0 .
In the measured excitation spectrum of the target Sn
nucleus, we observe three prominent peak structuresnear the π − emission threshold as depicted in Fig. 1of our original paper Ref. 2). The left most peak inthe smaller-mass side is assigned to the 1s pionic state
mainly coupling with a neutron hole state of (3s1/2 )−1
n .
†
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Condensed from the article in Phys. Rev. Lett. 125, 152505(2018)
University of Tokyo
RIKEN Nishina Center
University of Notre Dame
Kyoto University
GSI Helmholtzzentrum für Schwerionenforschung GmbH
Nara Women’s University
Tottori University
CNS, University of Tokyo
Stefan Meyer Institute for Subatomic Physics

References
1) K. Suzuki et al., Phys. Rev. Lett. 92, 072302 (2004).
2) T. Nishi et al., Phys. Rev. Lett. 120, 152505 (2018).
3) N. Ikeno et al., PTEP 2015, 033D01 (2015).

- 91 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Isotope identification in nuclear emulsion plate for double-hypernulcear
study†
S. Kinbara,∗1 H. Ekawa,∗2 T. Fujita,∗3 S. Hayakawa,∗4 S. H. Hwang,∗5 Y. Ichikawa,∗3 K. Imamura,∗3 R. Murai,∗1
M. K. Soe,∗1 M. Sweet,∗1 A. Takamine,∗3 A. M. M. Theint,∗1 H. Ueno,∗3 J. Yoshida,∗6 M. Yoshimoto,∗1 andK. Nakazawa∗1
Double hypernulcei such as double-Λ and Ξ hypernuclei provide information about Λ-Λ and Ξ-N interactions, which are important to understand the inner
structure of a neutron star. We have only two reliable
information from the NAGARA1,2) and KISO3,4) eventsin the E373 experiment. Other events are not uniquely
identiﬁed for the production and decay processes owing
to the remaining possible interpretations. The charge
identiﬁcation method is a key technique to understandthe multi-strangeness system.
To develop the method, we exposed eight nuclides (1 H,
2H, 3 H, 3 He, 4 He, 7 Li, 9 Be, and 11 B) to a nuclear emulsion at RIPS. To study the halo eﬀect in the ﬁnite focal
depth of objective lens, the exposed angle θ perpendicular to the emulsion surface was set to be θ ≈ 25◦ , 50◦ ,and 75◦ .
To recognize the charge of the particle, we measured
the track width and estimated the track volume thatreﬂect the energy-losses. Raw images were taken by microscope with a 100× objective lens and an 8 bits CCD
camera. A focused image, as shown in Fig. 1(a), consists of the most focused layers of raw images. Figure 1(b) is illustrated according to the following equation, Bout = 255 × (Bin − Bmin )/(Bmax − Bmin ), where
Bin , Bmax , and Bmin are the brightness of each pixel,
maximum, and minimum brightness in Fig. 1(a), respectively. Bin was enhanced to Bout . Figure 1(c) was illustrated by applying an algorithm called “diﬀerence ofGaussian” to Fig. 1(b). Then, a uniform backgroundimage was obtained by subtracting Fig. 1(b) from 1(c),as shown in Fig. 1(d). We measured the brightness
perpendicular to the track in the Fig. 1(d) and de-Fig. 1. Image processing method to obtain track width.
†
∗1
∗2
∗3
∗4
∗5
∗6

Condensed from the article in Prog. Theor. Exp. Phys. 2019,
011H01 (2019).
Physics Department, Gifu University
Department of Physics, Kyoto University
RIKEN Nishina Center
Department of Physics, Osaka University
Korea Research Institute of Standards and Science
Japan Atomic Energy Agency

Fig. 2. Vrα of each nucleus to α particle as a function oflog(1/sinθ).

ﬁned the track width as a distance between two inﬂection points, which were obtained by applying a ﬁtting
function, f = a × tanh(gauss(x, µ, σ)), to the data in
Fig. 1(e).
The track width depends on the photographic development. As a calibration source, we used α particles
which have monochromatic kinetic energy emitted fromnatural isotope 212 Po in the emulsion. We obtained thecalibration function of v α (d) with 68 α-particles, wherev α is the average track volume of an α-particle at depth
d from the emulsion surface.
The widths were measured for every 1 µm cell along
the track. Because the depths of the measured cellschanged along the track, a volume ratio Vrα to normalize
the α-particle for each nucleus was ∑obtained ∑for measured
90
90
α
V
/
volume Vi in ith cell as Vrα =ii=1i=1 v (di ),where di is the depth of the ith cell. We put 200 tracks
together at four areas for each nucleus in the exposed
emulsion and ﬁtted them according to log(1/sinθ), where
we set log(1/sinθ) to be ξ, as angle dependence of thevolume ratio, Vrα (ξ), to the volume of the α particle, as
shown in Fig. 2.
To conﬁrm the utility of the above method, it wasapplied to one track of a Ξ hypernucleus candidate detected in the E373 experiment. The nucleus of this trackis known as 3 H or 6 He by kinematical analysis. TheirVrα can be estimated by the data points of 1 H and 4 He.
Thus, we concluded that the nucleus would be a 6 He
nucleus with a likelihood ratio of 0.9.
References

1) H. Takahashi et al., Phys. Rev. Lett. 87, 212502 (2001).
2) J. K. Ahn et al., Phys. Rev. C 88, 014003 (2013).
3) K. Nakazawa et al., Prog. Theor. Exp. Phys. 2015,
033D02 (2015).
4) E. Hiyama, K. Nakazawa, Annu. Rev. Nucl. Part. Sci. 68,
131 (2018).

- 92 -

5. Hadron Physics (Theory)Ⅱ-5. Hadron Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Short range πJ/ψ − D D̄ ∗ interaction†
Y. Yamaguchi,∗1 Y. Abe,∗2 K. Fukukawa,∗3 and A. Hosaka,∗4
Exotic hadrons such as XY Z states reported in theheavy ﬂavor sector have been one of the interesting topics in hadron and nuclear physics.1) Especially, for the
exotic mesons near the thresholds, those states could be
realized as a hadronic molecule, which is a loosely boundor resonant state of multi-mesons.
Zc (3900) is an exotic state that has been reported
by BESIII,2) Belle,3) and other facilities.4,5) This state
has a nonzero electric charge that cannot be possessedby the standard cc̄ state. There have been various studies of Zc (3900), where multiquark states andhadronic molecules have been discussed (see Ref. 1)).
On the other hand, the non bound state explanation
has also been studied. Recent Lattice QCD simulation
by HALQCD6) indicates that Zc (3900) is a virtual state
induced by the strong πJ/ψ − DD̄∗ potential.
For the exotic state near the threshold, heavy hadroninteraction is important to understand the structure.
We study the short range πJ/ψ − DD̄∗ interaction described by (i) the meson exchange model, and (ii) quark
exchange model, and compare the results obtained bythese models.
In the meson exchange model, the D(∗) meson exchange is introduced, which is given as the Born term of
the t−channel scattering amplitude. The amplitude is
obtained by the eﬀective Lagrangians with respect to theheavy quark and chiral symmetries,7,8) which are given
by
[
]
gπ
LπHH = −Tr H1 γµ γ5 ∂ µ π̂ H̄1 ,
(1)
2fπ
[
]
LψHH = g ′ Tr J H̄2 ↔∂µ γ µ H̄1 + H.c.,(2)√where gπ = 0.59, g ′ = 4/ mψ m2D , and the pion decay
constant fπ = 93 MeV.
In the quark exchange model, the πJ/ψ − DD̄∗ interaction is described by the constituent quark model
Hamiltonian9,10)
)
(
αs
3
q
− C F⃗i · F⃗jHij= Kq + − br +
4
r
( 3
)
2
σ −σ2 rij
8παh
⃗i · S⃗j F⃗i · F⃗j .
S
−
e
(3)
3mi mj π 3/2
In Fig. 1, the cross sections of the πJ/ψ −DD̄∗ transition obtained using the two models are compared. The
cross section obtained using quark exchange is dominated by the spin-spin term, which is contributed by
the light quark dynamics instead of the charm quark
†
∗1
∗2
∗3
∗4

Condensed from the article in EPJ Web Conf. 204, 01007(2019)RIKEN Nishina Center
NEC
Suma Gakuen
RCNP, Osaka University- 93 -

Fig. 1. πJ/ψ − DD̄∗ cross sections obtained by (a) quark
exchange model, and (b) D(∗) exchange model.

dynamics. In comparison with that of quark exchange,
the cross section obtained by meson exchange is verysmall. A large diﬀerence is obtained between the twomodels, and it would be useful to understand the shortrange interaction in the πJ/ψ − DD̄∗ channel.
References

1) A. Hosaka, T. Iijima, K. Miyabayashi, Y. Sakai, S. Yasui,
Prog. Theor. Exp. Phys. 2016, 062C01 (2016).
2) M. Ablikim et al. [BESIII Collaboration], Phys. Rev. Lett.
110, 252001 (2013).
3) Z. Q. Liu et al. [Belle Collaboration], Phys. Rev. Lett.
110, 252002 (2013).
4) T. Xiao, S. Dobbs, A. Tomaradze, K. K. Seth, Phys. Lett.
B 727, 366 (2013).
5) V. M. Abazov et al. [D0 Collaboration], Phys. Rev. D 98,
052010 (2018).
6) Y. Ikeda et al. [HAL QCD Collaboration], Phys. Rev.
Lett. 117, 242001 (2016).
7) R. Casalbuoni et al., Phys. Rep. 281, 145 (1997).
8) A. V. Manohar, M. B. Wise, Heavy Quark Physics, (Cambridge University Press, Cambridge, England, 2000).
9) T. Barnes, E. S. Swanson, Phys. Rev. D 46, 131 (1992).
10) E. S. Swanson, Annals Phys. 220, 73 (1992).

Ⅱ-5. Hadron Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Proton decay matrix elements at physical quark mass
Y. Aoki,∗1,∗2 (current:∗3) Y. Kuramashi,∗4 and E. Shintani∗3

∗1
∗2
∗3
∗4

np=(1,1,1)

0.05

ts=18
ts=20

0.05

0.04

0.04

0.03

0.03

0.03

0.02

0.02

0.02

0.01

0.01

0.01

np=(0,1,2)

LL

0.04

np=(0,0,2)

0.05

W0

Proton decay is a smoking-gun signal of the physics
beyond the standard model (BSM). Grand uniﬁed theory (GUT) is the most natural origin of such an event
if observed. Despite no clear signal of the supersymmetry or any BSM phenomena at LHC, the idea of
unifying the known fundamental interactions is still
attractive. Estimate of the QCD contribution of the
proton decay matrix element is needed to test GUTs
against the proton lifetime bound obtained in the experiment. Also a reliable estimate of the matrix elements is desirable for planning the future generation
proton decay detectors.
The proton decay matrix elements are obtained bynumerical computation using lattice QCD. So far, the2 + 1 ﬂavor computations have provided the matrix elements with extrapolation to the physical ud quark
mass from the results at unphysically large masses.
This procedure yields one of the largest systematic
uncertainties. Settling this systematics is important1)
and possible using current lattice gauge ﬁeld ensembles
generated at the physical point.
We use gauge ﬁeld conﬁgurations of 2 + 1 ﬂavor QCD generated with non-perturbatively O(a)improved Wilson fermions by the PACS collaboration.2) As pointed in the previous works (see e.g.3) ),computations using the three-point functions aremandatory to obtain the matrix elements of a proton decaying into a pseudoscalar (and an anti lepton).
Last year we reported on the optimization of the parameters of smearing function of the quarks for interpolating operators of proton and mesons. Using this
we are extending the computation for the three-point
functions. Figure 1 shows the ratio of the three andtwo-point functions for proton decay form factor W0
for p → π 0 via LL operator (ϵijk (uTi CPL dj )PL uk ), forthree diﬀerent momentum values p⃗ = 2π/64∗ n⃗p . Fromthe plateau we will obtain the form factor that we areafter. Comparison of the two diﬀerent source-sink separation ts is performed, and they show consistent results in the middle. In this study we use 644 lattice atthe physical point mass. Last year we present a resultof low energy constant α computed on 644 and 964 volumes. As the results from two volumes are consistent,
we expect 644 is also good for the form factors.
We need several further steps to obtain the from factors in the physical unit (GeV2 ) and renormalized ina convenient renormalization scheme for phenomenological use. For the renormalization one needs to solve
the operator mixing due to an explicit chiral symmetry

0
0

5

10

t

15 20

0
0

5

10

t

15 20

0
0

5

10

t

15 20

Fig. 1. Time dependence of the ratio of three and twopoint functions for proton decay form factor W0 for
p → π 0 via LL operator (ϵijk (uTi CPL dj )PL uk ). The
middle points should converge to the form factor in theasymptotic limit of large source-sink separation ts , thus
develops a plateau.

breaking of the Wilson fermion formulation. The nonperturbative renormalization4) can be applied to solve
the mixing and at the same time to obtain the totallyrenormalized operator in the MS scheme. The use of
RI/SMOM schemes5) are under investigation. Finallythe lattice cutoﬀ squared 1/a2 needs to be multiplied.
This study has shown that we have reasonably a
good signal for the form factors and the low energy constants (last year) at the physical quark masses. Witha full statistics and a supplemental mass dependence
analysis, as well as with a completion of the operator
renormalization, this work provides results of proton
decay matrix elements with no systematic error fromchiral extrapolation for the ﬁrst time. There is another on-going project6) to calculate the same matrix
elements with domain-wall fermions with very coarse
lattice but with a better control of chiral symmetry.
These two studies are complementary to each otherand together will bring us to the ﬁnal goal of estimating the proton decay matrix elements for pseudo-scalarﬁnal states with direct simulation at the physical point.
References

1) A. Martin, G. Stavenga, Phys. Rev. D 85, 095010(2012).
2) Y. Kuramashi, talk given at Lattice 2017.
3) Y. Aoki, T. Izubuchi, E. Shintani, A. Soni, Phys. Rev.
D 96, 014506 (2017).
4) Y. Aoki, C. Dawson, J. Noaki, Soni, Phys. Rev. D 75,
014507 (2007).
5) C. Sturm, Y. Aoki, N. Christ, T. Izubuchi, C. Sachrajda, A. Soni, Phys. Rev. D 80, 014501 (2009).
6) J. Yoo, Y. Aoki, T. Izubuchi, S. Syritsyn, arXiv:1812.09326.

KEK Theory Center
RIKEN Nishina Center
RIKEN R-CCS
CCS, University of Tsukuba- 94 -

Ⅱ-5. Hadron Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

The πγ → ππ transition and the ρ radiative decay widthfrom lattice QCD†
C. Alexandrou,∗1,∗2 L. Leskovec,∗3 S. Meinel,∗3,∗4 J. Negele,∗5 S. Paul,∗2 M. Petschlies,∗6 A. Pochinsky,∗5
G. Rendon,∗3 and S. Syritsyn∗7,∗4
Lattice QCD calculations of hadronic matrix elements of external currents are straightforward as longas the initial and ﬁnal states contain no more than asingle, stable hadron. For multi-hadron states, however, the relation between the ﬁnite-volume matrix
elements computed on the lattice and the physicalinﬁnite-volume matrix elements of interest is quite
nontrivial, and is known only for certain cases. The
formalism for 1 → 2 transition matrix elements was
pioneered by Lellouch and Lüscher in 2000,4) and waslater generalized by other authors to more complicatedsystems.5–10)
Our collaboration is using this formalism to compute
several 1 → 2 transition matrix elements of interestin high-energy and nuclear physics, including semileptonic weak decays such as B → ππℓν̄. The present
work considers the electromagnetic process πγ → ππ,
where we take the ππ system in a P wave and isospin
1, and allow the photon to be virtual. The hadronicmatrix element for this process can be written as

Fig. 1. Our results for the πγ → ππ transition amplitude
as a function of the ππ invariant mass and the photon
virtuality. The magenta boxes show the 1σ uncertain√
ties in a s, a2 q 2 , and V/a.

2iV(q 2 , s) νµαβϵϵν (P, m)(pπ )α Pβ , (1)mπwhere P and ϵ are the four-momentum and polarization of the two-pion ﬁnal state, pπ is the fourmomentum of the single-pion initial state, and theamplitude V(q 2 , s) depends on the two scalar variables q 2 = (pπ − P )2 and s = P 2 . Our calculation
was performed with 2 + 1 ﬂavors of clover fermions,at a pion mass of approximately 320 MeV. Our results for V(q 2 , s) are shown in Fig. 1. This amplitude shows the expected enhancement associatedwith the ρ resonance, which corresponds to a poleat spole ≈ m2ρ + imρ Γρ . One very interesting result,seen for the ﬁrst time, is the following: for large s,V(q 2 , s) falls oﬀ signiﬁcantly slower compared to what
one would expect for purely resonant behavior.
The residue of V(0, s) at s = spole is equal to the
product of the ρ-ππ and ρ-πγ couplings. Our result for the photocoupling is |Gρπγ | = 0.0802(32)(20),⟨ππ|J µ |π⟩ =

†

∗1
∗2
∗3
∗4
∗5
∗6
∗7

where the ﬁrst uncertainty originates from the twopoint and three-point function ﬁts, while the second
uncertainty is an estimate of the parametrization dependence in the analytic continuation. Despite theheavier-than-physical light-quark masses, the lattice
result for |Gρπγ | is already close to the value extracted
from the measured ρ radiative decay width.11)
References
1) M. Lüscher, Nucl. Phys. B 354, 531 (1991).
2) R. A. Briceño, J. J. Dudek, R. D. Young, Rev. Mod.
Phys. 90, 025001 (2018).
3) C. Alexandrou et al., Phys. Rev. D 96, 034525 (2017).
4) L. Lellouch, M. Lüscher, Commun. Math. Phys. 219,
31 (2001).
5) C. J. D. Lin, G. Martinelli, C. T. Sachrajda, M. Testa,
Nucl. Phys. B 619, 467 (2001).
6) N. H. Christ, C. Kim, T. Yamazaki, Phys. Rev. D 72,
114506 (2005).
7) M. T. Hansen, S. R. Sharpe, Phys. Rev. D 86, 016007(2012).
8) R. A. Briceño, Z. Davoudi, Phys. Rev. D 88, 094507(2013).
9) R. A. Briceño, M. T. Hansen, A. Walker-Loud, Phys.
Rev. D 91, 034501 (2015).
10) R. A. Briceño, M. T. Hansen, Phys. Rev. D 92, 7,074509 (2015).
11) C. Patrignani et al. (Particle Data Group), Chin. Phys.
C 40, 100001 (2016).

Condensed from the article in Phys. Rev. D 98, 074502(2018)
Department of Physics, University of Cyprus
Computation-based Science and Technology Research Center, Cyprus InstituteDepartment of Physics, University of Arizona
RIKEN Nishina Center
Center for Theoretical Physics, Massachusetts Institute ofTechnology
Helmholtz-Institut für Strahlen- und Kernphysik, Universityof Bonn
Department of Physics and Astronomy, Stony Brook University- 95 -

Ⅱ-5. Hadron Physics (Theory)

RIKEN Accel. Prog. Rep. 52 (2019)

Neutron stars from an eﬀective quark theory of QCD†
T. Tanimoto,∗1 W. Bentz,∗1,∗2 and I. C. Cloët∗3
The study of neutron star matter has attracted increased attention recently because of the observationof massive neutron stars exceeding two solar masses1)
and gravitational wave measurements of a binary neutron star merger event.2) In this work, we investigate
whether a single eﬀective quark theory of QCD which
can describe both the structure of free and in-medium
hadrons as well as nuclear systems,3) can also produce
properties for neutron stars which agree with data.
For this purpose, we use the two-ﬂavor Nambu-JonaLasinio (NJL) model4) with the proper-time regularization scheme, which incorporates important aspectsof conﬁnement.3)
We calculate the eﬀective potentials of nuclear matter(NM) and quark matter (QM) in the mean ﬁeld approximation as functions of two independent chemical potentials for baryon number and isospin. The Fermi gasof electrons is also included so as to achieve β equilibrium and charge neutrality. Besides the vacuum (Mexican hat shaped) part, the eﬀective potentials containpieces which describe the Fermi motion of composite
nucleons (case of NM) or constituent quarks (case of
QM) in scalar and vector mean ﬁelds. The descriptionof the nucleon is based on the Faddeev method in thequark-diquark approximation, taking into account boththe scalar and axial vector diquark channels. In the QM
sector we also take into account the pairing of quarks
in the scalar diquark channel, which gives rise to a gap(color superconductivity). We use the Gibbs equilibrium conditions to describe the phase transition fromNM to QM with an intermediate mixed phase. The
constituent quark mass (scalar mean ﬁeld), the gap,
and the isoscalar- and isovector-vector mean ﬁelds are
determined self consistently by minimization of the effective potential for ﬁxed chemical potentials.
The model parameters in the single nucleon and NM
sector are the same as in Ref. 3). In order to realize aphase transition to QM at reasonable transition densities (between 2ρ0 and 4ρ0 , where ρ0 = 0.16 fm−3 ) witha stable QM component, we found that it is possible touse the same value for the pairing strength in QM as
for the scalar diquark interaction in the single nucleon
sector, but the vector couplings must be smaller thanin NM by a factor of 0.5–0.68.In the results below we
use a reduction factor of 0.68 for both isoscalar- andisovector vector couplings in QM.
By using our equation of state as an input to solve theTolman-Oppenheimer-Volkoﬀ equations, we can calcu†
∗1
∗2
∗3

Condensed from an article by T. Tanimoto et al., to be published in Phys. Rev. C (2019).
Department of Physics, Tokai University
RIKEN Nishina Center
Physics Division, Argonne National Laboratory- 96 -

late the properties of neutron stars. From our results,
shown in Figs. 1 and 2, we can conclude that our NJL
model description, which has been very successful forsingle hadrons and nuclear systems, leads to a satisfying scenario also for the phase transition to QM andthe resulting properties of neutron stars.

Fig. 1. Neutron star mass vs. central baryon density. The
solid line shows the pure NM case, and the dashed line
shows a phase transition to QM at about 3ρ0 . PSR
J0348 + 0432 and GW170817 indicate the observed values of star masses of Refs. 1–2), respectively.

Fig. 2. Mass-radius relation for neutron stars. For explanation of lines and symbols, see the caption to Fig. 1.

References

1) J. Antoniadis et al., Science 340, 6131 (2013).
2) B. Abbott et al., (LIGO Scientific, Virgo), Phys. Rev.
Lett. 119, 161101 (2017).
3) I. C. Cloët, W. Bentz, A. W. Thomas, Phys. Rev. Lett.
109, 182301 (2012).
4) Y. Nambu, G. Jona-Lasinio, Phys. Rev. 122, 345(1961); 124, 246 (1961).

6. Particle Physics

Ⅱ-6. Particle Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Baryon spectrum of an SU(4) composite Higgs theory†
E. T. Neil∗1,∗2 [for the Tel Aviv-Colorado Collaboration]
The possibility that the Higgs boson is not a fundamental scalar, but rather a composite bound stateof some new strongly-coupled sector, provides an intriguing scenario for new physics beyond the Standard
Model. Current measurements of the properties of the
Higgs boson provide only weak constraints on the possible scale of compositeness for the Higgs. If the Higgs
is indeed a composite bound state, then there will be
an associated spectrum of other new composite particles which may be within discovery reach of the Large
Hadron Collider (LHC) or other future colliders. The
overall pattern of the spectrum is directly related tothe underlying fundamental structure, just as the spectrum of QCD is predicted by the quark masses and thegauge symmetry group SU(3).
The full spectrum of a strongly-coupled gauge theory
cannot be predicted by traditional perturbative methods. Instead, lattice simulations can be used to obtain
numerical but systematically controlled results for the
spectrum of a particular theory. In this work, we choseto study an SU(4) gauge theory proposed as a composite Higgs model by Ferretti.1) This model includes
two types of fermions, charged under the fundamental
4 and “sextet” two-index antisymmetric 6 representations of SU(4). We have developed a lattice code capable of dealing with fermions in multiple representations, with previous results on the “meson” spectrum2)
and thermodynamic properties of this theory.3)
Composite bound states can be enumerated byclassifying all SU(4)-singlet combinations of fermions.
Writing the 4 fermions as q and the 6 fermions as Q,
we can identify bound states such as qqqq which are
direct analogues of the familiar QCD baryons. However, there is an additional baryon-like bound statecomposed of qqQ fermions. This “chimera baryon” isespecially interesting in the context of the composite
Higgs model, in which it has the same quantum numbers as the fundamental top quark. Mixing between
the top quark and this top-partner chimera is responsible for the generation of the observed top mass.
Using standard lattice spectroscopy techniques, we
compute the mass of the chimera and the other baryonlike states for a range of input fermion masses. The
physical limit for the composite Higgs model requires
taking the massless limit for the sextet fermions m6 →0, but the other fermion mass m4 remains a free parameter of the model. Figure 1 shows our results forthe spectrum versus m4 with 1σ error bands. The units
are set in terms of F6 , the sextet NGB decay constant,†∗1∗2

Fig. 1. Spectrum of bound states computed from lattice simulation for SU(4) gauge theory with two Diracfermions in the 4 and 6 (“sextet”) gauge representations. Bound-state masses (vertical axis) are shown versus the squared fundamental Nambu-Goldstone boson
2(NGB) mass MP,
4 , which is proportional to the input
fermion mass m4 , treated as a free parameter. In thecontext of the composite Higgs model, F6 is boundedby experiment to be F6 ≳ 1 TeV, so the plot can beread in TeV units. Most bound states are seen to beheavier than 5 TeV for the entire parameter space.

which is related to the Higgs vacuum expectation
value; experimental constraints require F6 ≳ 1 TeV,
so the plot units are equivalent to TeV scale.
We see that for the full parameter space, all boundstates are found to be quite heavy, with masses of order 5 TeV or larger, and thus likely out of the reach of
the LHC. However, the fundamental pseudo-NambuGoldstone boson (NGB, purple curve) may be withinreach for at least part of the parameter space. Future
lattice studies will focus on non-perturbative contributions to the Higgs potential in this model, which should
greatly constrain the allowed parameters of the model.
References
1) G. Ferretti, JHEP 1406, 142 (2014).
2) V. Ayyar, T. DeGrand, D. C. Hackett, W. I. Jay,
E. T. Neil, Y. Shamir, B. Svetitsky, Phy. Rev. D 97,
no. 7, 074505 (2018).
3) V. Ayyar, T. DeGrand, D. C. Hackett, W. I. Jay,
E. T. Neil, Y. Shamir, B. Svetitsky, Phy. Rev. D 97,
no. 11, 114502 (2018).

Condensed from the article in Phy. Rev. D 97, no. 11, 114505(2018)RIKEN Nishina Center
Department of Physics, University of Colorado, Boulder- 97 -

Ⅱ-6. Particle Physics

RIKEN Accel. Prog. Rep. 52 (2019)

Updated empirical formulae of the masses of elementary particles
Y. Akiba,∗1
formulacalculated(c)measured(m)|c/m − 1|1/3e1/(12π 2 )ϵ0 (1+(1/4)(1/(6π)2 ))−1 Mpl
0.511002 MeV 0.510998946 ± 0.0000000031 MeV 5.9 × 10−61/3µ
3/2ϵ0 (1 − 1/(2π)+3/(4π)2 )−1 Mpl
105.6594 MeV 105.6583745 ± 0.0000024 MeV 9.6 × 10−61/3
τ9πϵ0 (1 − 1/(8π)+(5/4)(1/(6π)2 ))−1 Mpl
1.77684 GeV
1.77686 ± 0.12 GeV
1.3 × 10−5
2 1/3
t
8 × (6π) ϵ0 Mpl
172.1 GeV
173.4 ± 0.75 GeV
7.5 × 10−3
1/3c
12ϵ0 Mpl
1.24 GeV
1.28 ± 0.025 GeV(MS at mc )3.4 × 10−2
−2 1/3u
8 × (6π) ϵ0 Mpl
2.07 MeV
2.15 ± 0.15 MeV (MS at 2 GeV) 3.8 × 10−2
1/3
2 −1
b
3 × (6π)ϵ0 (1+1/4π+3/(4π) ) Mpl
4.18 GeV
4.18 ± 0.03 GeV(MS at mb )≤ 2 × 10−31/3s
ϵ0 Mpl91.8 MeV
93.8 ± 2.4 MeV (MS at 2 GeV) 2.1 × 10−2
−1
−1 1/3d(6π) ϵ0 (1+1/6π) Mpl
4.63 MeV
4.7 ± 0.2 MeV (MS at 2 GeV) 1.5 × 10−2
2 1/4
2 −1/2
Z 1/(8π )ϵ0 (1+1/12(1/(6π))+1/12(1/(6π) ))Mpl 91.1862 GeV
91.1876 ± 0.0021 GeV
1.5 × 10−5
−1/4
2 1/4
2 −1/2W
2/(8π )ϵ0 (1 − 1/(4π) − 2/(4π) )Mpl
80.387 GeV
80.385 ± 0.015 GeV
2.5 × 10−5
1/4
H
21/2 /(8π 2 )ϵ0 (1+1/(4π)+1/(4π)2 )−1/2 Mpl
125.14 GeV
125.1 ± 0.2 GeV
3.8 × 10−4

)
( ∫
m(t)
αs (t)
dt ,= exp −m0π

In my article in APR20171) I reported empiricalformulae of the masses of charged leptons (e, µ, τ ),quarks (t, c, u, b, s, d), gauge bosons (Z, W ), andHiggs boson (H). The formulae yield the masses interms of the Planck mass Mpl and a dimensionlessconstant ϵ0 = 2 × (6π)−48 . There is no adjustableparameter in the formulae. Note that the value of ϵ0is consistent with the product of the Hubble constantH0 and the Planck time tpl = 1/Mpl :where t = log µ2 and αs (t) is the running QCD coupling constant at the scale µ. The value of αs (t) in the
PDG2016 review is used for the calculation.
The formulae, calculated values (c) using the formulae, measured values (m), and diﬀerence |c/m − 1|are summarized in the table above. The calculations
reproduce the measured mass values well.
The agreement is within the uncertainty of the measured mass or the Planck mass (2.4 × 10−5 ). There isa pattern in the formulae. The formulae can be summarized as1
1/3
mf = Nf (6π)nf ϵ0 (1+δl )−1 Mpl ,2
2cB 1/4
ϵ (1+δB )−1 Mpl ,mB =8π 2 0where mf and mB are the masses of charged fermions(leptons and quarks) and bosons, respectively. Nf aresmall positive integers, nf are integers ranging from
−2 to 2, and δl and δB are small real numbers. cZ =0, cW = −1/4, and cH = 1/2. The pattern suggests
the existence of a rule that determines the formulae.
1/3
Note that all fermion masses are of order of (6π)nf ϵ0with −2 ≤ nf ≤ 2 and the boson masses are of the
1/4
order of 1/8π 2 ϵ0 . Presumaby, this part is the mainpart of the mass, and (1 + δl ) and (1 + δB ) are thecorrection factors due to interactions.
A model to explain these formulae is reported in a
separate article.4)

H0 × tpl = (1.211 ± 0.014) × 10−61 ,−48= 1.220608 × 10−61 .
0 ≡ 2 × (6π)
Here, the WMAP nine-year value of H0 is used. Thissuggests that the masses of elementary particles are
related to the expansion of space-time.
Here, I report a small update of the formulae for b
and d quarks and Z, W, H bosons. The revised formulae have better agreement with the data.
The mass values calculated using the formulae arecompared with the measured ones. For the calculation,
the value of Planck mass from CODATA2) is used:
Mpl = 1.220910 ± 0.000029 × 1019 GeV.
The measured values of the particle masses are takenfrom PDG2016.3) In QCD, the mass of a quark is dependent on the scale and the scheme. In the PDG
review, the mass of quarks other than the t quark are
given in the MS scheme at µ = 2 GeV for the u, d, squarks and at µ = mq for the b and c quarks. For the tquark, the measured mass is considered to be the polemass. The formula for a quark is assumed to yield theMS mass at the Z boson mass mZ . The ﬁrst-orderrenormalization group equation (RGE) given below isused to correct for the mass value at the scale mZ to
the mass at the scale the PDG uses:∗1

References
1) Y. Akiba, RIKEN Accel. Prog. Rep. 51 (2017).
2) P. J. Mohr et al., Rev. Mod. Phys. 88, 035009 (2016).
3) C. Patrignani et al. (Particle Data Group), Chin. Phys.
C 40, 100001 (2016).
4) Y. Akiba, RIKEN Accel. Prog. Rep. 52 (2018).

RIKEN Nishina Center- 98 -

Ⅱ-6. Particle Physics

RIKEN Accel. Prog. Rep. 52 (2019)

A model of the empirical mass formulae of elementary particles
Y. Akiba∗1′

In the preceding article1) empirical formulae ofthe masses of charged leptons (e, µ, τ ), quarks(t, c, u, b, s, d), and gauge and Higgs bosons (Z, W,
H) are presented. Here I report a model that can produce these mass formulae.
In the model, there is the minimum duration of time,
which is the Planck time τpl = 1/Mpl = 5.3912 ×
10−44 sec. A term of the action (integral of Lagrangian) of a particle is a wedge product of 48 “primordial actions” (PAs) that are selected from the folPAs:
lowing 64 PAs.

a reduced value in the form of ±m(6π)n is (τ 3 )s ϵ0 ,where ϵ0 = 2 × (6π)−48 , s ∈ {0, 1}, s′ ∈ {0, 1},
and m, n(0 ≤ n ≤ 4) are integers. The valuesof s, s′ , n, and m are determined by the selectionof the subset {ŝ1 , · · · , ŝ48 } from SP A . The reduced
values of 48 wedge products of PAs that correspondto the actions of charged leptons (e, µ, τ ), neutrinos (ν1 , ν2 , ν3 ), quarks (u, c, t, d, s, b), and bosons(Z, W, H) are summarized in Table 1. In the table,
U and D stand for U -type and D-type quarks, respectively, when their mass is ignored.
The mass of particles can be obtained from this table. In the below, I shows how the mass formula of theelectron can be obtained from the table as an example.
The action of the electron is

1 µ ν a 1
1 3 1 c 3
I σ τ ,εi,ετ ,εI τ ,
6π
6π
6π
6π
1
1
− I c , − εi, i, I c , −ε, ε, 1.
2π
2π

SP A =

dSe = 4(6π)2The wedge product operator ∧ and orientation operator (sign operator) ε have the following reduction rules:α̂∧β̂∧γ̂ =α̂β̂γ̂
0(α̂β̂ = −β̂ α̂, β̂γ̂ = −γ̂ β̂, γ̂ α̂ = −α̂γ̂)(otherwise),

Table 1. The action of particles per Planck Time.

e
µ
τ
ν1
ν2
ν3
U
u
c
t
D
d
s
b
Z
H
W
∗1

iτ

−12
−3
−12
−12

1

3

3

iτ
1
27
1+4

ϵ0
i

†
ψ̂15 = 4(6π)2 0 iτ 3 ,idˆ16 ψ̂15†
ψ̂15 = 0 iτ 3,
Â18 ∧ ψ̂15
µ0e |ψ15 |2 = 3 0 .

1
3
3

1/3

Here, µ0e = (12π 2 )−1 ϵ0 . The terms 4(6π)2 ϵ0 iτ 3 ,ϵ0 iτ 3 , and 3ϵ0 correspond to the kinetic, the EM interaction, and the mass term, respectively. From these
relations, the mass formula of the electron can be determined.

−2
2

−4

±2

±2

±8
±24
±8

1
−12

3

6
1
6

3

3

18

+ 3 0.

1/3

Here, s is scalar. Following these rules, a 48 wedge
product of PAs, dS = ŝi1 ∧ · · · ∧ ŝi48 , is reduced to(6π)ϵ0i τ33

and the vectors u1 =Here, |ψ15 | = (6π)ϵ0
1
1
1
2
2
(u1 , u2 , u3 ) and u = (u1 , u22 , u23 ) satisfy u1 × u2 =(−1, −1, −1) and u1 · u2 = 1. The operators id16 andψ15 correspond to the diﬀerential operator iσ µ ∂µ and†corresponds to its
the electron ﬁeld operator, and ψ15
conjugate. One can show that(ε∧) = 2 .

3

0 iτ

1/3
1
2
3
0 (1 + iσ + iσ + iσ ),ψ̂15 = |ψ15 |τ 2 (u21 σ 1 + u22 σ 2 + u23 σ 3 ),†= |ψ15 |τ 1 (u11 σ 1 + u12 σ 2 + u13 σ 3 ),
ψ̂15
1/3
Â18 = (6π)−2 0 (1 + iσ 1 + iσ 2 + iσ 3 ).

n(6π)2 ϵ0
iτ 3
4
4
4
−12
4
−12
−12
−4
−4
−4
−12
−12
−12
4
12
4
12

+

idˆ16 =s ∧ α̂ = sα̂, s1 ∧ s2 = 0, α̂ ∧ s ∧ β̂ = sα̂β̂ ,n3Each term of the action can then be written as a product of the following “operators”“operators”:(α̂β̂ = −β̂ α̂)(α̂β̂ = β̂ α̂),α̂β̂0α̂ ∧ β̂ =

0τ

27
1
27

dSe =

1+

1 1
4 (6π)2

µe =

1+

1 1
4 (6π)2†
idˆ16 ψ̂15
ψ̂15 + µe |ψ15 |2 ,
−1

1 1/3
12π 2 0 .

Similarly, the mass formulae of µ, τ, ν1 , ν2 , ν3 , u, d,s, c, b, t, Z, W , and H can be obtained from each row
in the Table 1.

18
18
±18
18

Reference
1) Y. Akiba, RIKEN Accel. Prog. Rep. 52 (2018).

RIKEN Nishina Center- 99 -

7. Astrophysics and Astro-Glaciology

Ⅱ-7. Astrophysics and Astro-Glaciology

RIKEN Accel. Prog. Rep. 52 (2019)

High-sensitivity sulfur isotopic measurements for Antarctic ice core
analyses†
K. Takahashi,∗1 Y. Motizuki,∗1 and Y. Nakai∗1
Sulfur isotopic measurements have been widely applied in earth sciences to investigate the origin and behavior of sulfur compounds in the lithosphere, hydrosphere, and atmosphere. Recently, sulfur isotopic analyses have also been utilized to elucidate the origin andcirculation of various materials in nature in order to develop various scientific research fields, such as environmental, biological, archaeological, and so on.1,2) Sulfur
isotopic compositions are reported as per mil ( ) variations relative to a standard material (typically Vienna
Canyon Diablo Troilite, VCDT) as follows:δ 34 S = (34 S/32 S)sample /(34 S/32 S)standard − 1
In Antarctic ice and snow samples, it is considered that the sulfur isotopic ratios reflect the origin
and pathway of sulfur compounds from their precursor
materials, thus indicating the Antarctic environmental(hydrospheric and atmospheric) conditions. Sulfate andmethane-sulfonic acids are the main sulfur components
in ice and snow samples, and the sulfate ion is particularly dominant among those species. Several studies have examined the origins and geochemical implications of sulfates based on the sulfur isotopic composition of Antarctic ice and snow samples. Several studies3,4) have analyzed the sulfur isotopic compositions ofsurface snow to investigate the origin of sulfate aerosols
and their alteration during transport from coastal areas to the Antarctic interior. Sulfur isotopic compositions in ice cores elucidate the paleo-climatic changes:
Cole-Dai et al.5) and Baroni et al.6) measured the sulfur
isotopic compositions of ice core samples influenced bylarge volcanic eruptions (e.g. Pinatubo, Tambora) toinvestigate the origin and isotopic fractionation of sulfates during their transport through the stratosphere.
In those studies, more than 200 g (containing more than
150 nmol sulfate) samples were required to obtain sulfur
isotopic (δ 34 S) data.
We developed a high-sensitivity sulfur isotopic (δ 34 S)
analytical system equipped with an elemental analyzer,
a cryo-flow device, and an isotope ratio mass spectrometer, and established a measurement and calibration
procedure. Using this system, we precisely measured
the sulfur isotopic ratio (δ 34 S) of samples containing
5–40 nmol sulfate. Test runs were performed on samples from the Antarctic shallow ice core DF01. Figure 1
shows the depth profiles of the sulfate concentration andthe sulfur isotopic ratio (δ 34 S) for the samples takenfrom DF01 at a depth of 8.49 to 9.39 m. The sample taken from a depth of 8.79 m depth is regarded as†∗1

Fig. 1. δ 34 S (solid circles) and sulfate concentration (opentriangles) depth profiles for the two analyzed sections
from ice core DF01. The minimum δ 34 S value and thepeak sulfate concentration at 8.79 m depth in section 2
are considered to be due to the AD 1883 eruption of the
Krakatau volcano.

corresponding in time to the AD 1883 eruption of the
Krakatau volcano. As shown in Fig. 1, it showed a peaksulfate concentration in its depth profile, which is considered to have resulted from a large volcanic eruption.
The δ 34 S value obtained at that depth in the sample
was distinct from the values at other depths and consistent with the reported values for volcanic sulfates
The analytical system developed herein is a powerfultool for trace sulfur isotopic analyses. The results obtained from the DF01 ice core samples are the first step
towards elucidating high-time-resolution (less than oneyear) paleo-environmental changes through sulfur isotopic analyses. Furthermore, the other analyses method
shown in this study can be applied not only to the analyses of ice core samples, but also to other analyses, suchas the analysis of tree rings,2) which require small-scale
analyses. Therefore, this measurement system is expected to be widely applicable to sulfur isotopic analyses in environmental and geochemical sciences.
References
1) F. Fourel et al., Proc. Earth Planetary Science 13, 232(2015).
2) P. M. Wynn et al., Biochemistry 114, 255 (2013).
3) R. Uemura et al., Geophys. Res. Lett. 43, (11), 5878
(2016).
4) N. Akata et al., Seppyo 73, (5), 339 (2011).
5) J. Cole-Dai et al., Geophys. Res. Lett. 36, (22), L22703(2009).
6) M. Baroni et al., Science 315, 84 (2007).

Condensed from the article in Rapid. Comm. Mass. 32, 1911(2018)RIKEN Nishina Center- 101 -

Ⅱ-7. Astrophysics and Astro-Glaciology

RIKEN Accel. Prog. Rep. 52 (2019)

Mass Measurements with the Rare-RI Ring for the A = 130 r-process
Abundance PeakS. Naimi,∗1 H. F. Li,∗1,∗2 Y. Abe,∗1 Y. Yamaguchi,∗1 D. Nagae,∗1 F. Suzaki,∗1 M. Wakasugi,∗1 H. Arakawa,∗3
W. B. Dou,∗3 D. Hamakawa,∗3 S. Hosoi,∗3 Y. Inada,∗3 K. Inomata,∗3 D. Kajiki,∗3 T. Kobayashi,∗3 M. Sakaue,∗3
K. Yokoya,∗3 T. Yamaguchi,∗3 R. Kagesawa,∗4 D. Kamioka,∗4 T. Moriguchi,∗4 M. Mukai,∗4 A. Ozawa,∗4 S. Ota,∗5
N. Kitamura,∗5 S. Masuaoka,∗5 S. Michimasa,∗5 D. S. Ahn,∗1 H. Baba,∗1 N. Fukuda,∗1 Y. Shimizu,∗1 H. Suzuki,∗1
H. Takeda,∗1 C. Y. Fu,∗2 Z. Ge,∗1,∗2 S. Suzuki,∗2 Q. Wang,∗2 M. Wang,∗2 Yu. A. Litvinov,∗6 G. Lorusso,∗7 andT. Uesaka∗1
In the fall of 2018, we have conducted an experimentat the Rare-RI Ring (R3) to measure masses of nuclei
in the south-west region of 132 Sn. As it has been shown
from sensitivity studies1) masses of nuclei in the region
around N = 82 has the most signiﬁcant impact on the
A = 130 r-process abundance peak. We have measured
masses of the most exotic nuclei approaching N = 82,
namely 122 Rh, 123, 124 Pd and 125 Ag isotopes.
Particles of interest were produced at RIBF by impinging a 40-pnA Uranium beam on a 5-mm thick Be
target. Particles were identiﬁed at BigRIPS by energy
loss in an Ionization Chamber (IC) placed at F3 andtheir Time-of-Flight (ToF) from F3 to F5. After injection into the R3 and storage for about 1 ms, equivalent
to almost 2000 turns, the particles were extracted. Figure 1 shows the PID at F3 of all events a BigRIPS inyellow and extracted events after R3 shown in pink.
The mass will be determined from the total time-ofﬂight in the storage ring and a velocity correction. The
mass determination of a particle with m1 /q1 requires
also a reference particle with known mass m0 /q0√m1
1 − β12
m0 T1
=
,
(1)
q1
q0 T0 1 − ( TT1 β1 )20

In Table 1, we show the number of extracted events
preliminarily conﬁrmed with the PID. The overall extraction eﬃciency was lower than expected and was lessthan 1% for the reference particle. The data analysis isbeing carried out.
In the future we aim at studying even more exotic,
relevant nuclides in this region.

with β1 being the particle of interest velocity that is measured along the beamline before injection. The time-ofﬂight of the reference particle T0 and particle of interest
T1 inside the ring are determined by a procedure detailed
elsewhere.2)
Table 1. Preliminary total events extracted after the ring.
Isotope
127
Sn
126
In
125
Cd
124
Ag
123
Pd
122
Rh
∗1
∗2
∗3
∗4
∗5
∗6
∗7

Events
104
287
140
1261
122
2

Isotope
128
Sn
127
In
126
Cd
125
Ag
124
Pd

Events
178
157
4965
406
11

RIKEN Nishina Center
IMP, CAS, China
Department of Physics, Saitama University
Department of Physics, University of Tsukuba
CNS, University of Tokyo
GSI Helmholtz Center, Darmstadt, Germany
NPL, University of Surrey

Fig. 1. Particle Identification (PID) showing the energy loss
in the Ionizarion Chamber (IC) at F3 and ToF from F3
to F5. In yellow are shown events at BigRIPS and inpink are shown extracted events after R3. Particles ofinterested are labeled in green, while reference particles
are labeled in black.

References

1) M. Mumpower et al., J. Phys. G 42, 034027, (2015).
2) H. Li et al., in this report.

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8. Accelerator

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Construction of New 28-GHz ECR ion source for RILAC
T. Nagatomo,∗1 Y. Higurashi,∗1 J. Ohnishi,∗1 A. Uchiyama,∗1 K. Kumagai,∗1 M. Fujimaki,∗1 T. Nakagawa,∗1
T. Ohki,∗2 M. Tamura,∗2 K. Kaneko,∗2 K. Oyamada,∗2 A. Yusa,∗2 H. Yamauchi,∗2 and O. Kamigaito∗1
Since 2017, we have been upgrading the RIKEN
linear accelerator RILAC for the RIBF project1) andto synthesize new super-heavy elements (SHEs) withatomic number Z ≥ 119. In the upgrade,2) some of thelatter acceleration cavities of RILAC were planned to be
replaced with superconducting quarter-wavelength resonators (SC-QWRs) to increase the energy of the beamwith M/Q = 6 from 5 MeV/nucleon to 6 MeV/nucleon
for the synthesis of SHEs. In the SHE project, thehigh intense metallic ion beams, such as Va and Cr(> 10 particle µA), are required from the ion source.
In addition, because the SC-QWRs are driven by theﬁxed frequency, these SC-QWRs are skipped in thevariable frequency operation especially for the RIBF
project. Thus, high-intensity ion beams with a higher
charge than before. For example, Ca16+ beam of∼ 100 electric µA is required to achieve enough energy
without the SC-QWRs to meet the variable frequency
acceleration scheme of RIBF. To meet these requirements, we decided to construct a new electron cyclotron
resonance ion source that consists of fully superconducting mirror magnets (SC-ECRIS) with a high-power
28 GHz gyrotron microwave generator.
Figure 1 shows the current status of the new 28 GHz
SC-ECRIS and gyrotron microwave generator with low
energy beam transport (LEBT) constructed in the injection room of the RILAC accelerator building. The
SC-ECRIS and microwave generator are the same models as the uranium ion source of RILAC II, which is predominantly used for RIBF project (for details, please
see the references).3–5) The new SC-ECRIS is designed
to be operated with 18 and 28 GHz microwaves. In
Fig. 1, the LEBT following the ECRIS consists of asolenoidal lens, an analyzing magnet sandwiched by twosteering magnets, a diagnostics chamber, and anothersolenoidal lens. In the diagnostics chamber, a Faraday
cup and a pepper-pot type emittance meter (PPEM)
were installed. The 40 Ar11+ beam of ∼ 90 electric µA
was successfully extracted from the new SC-ECRIS as
the ﬁrst beam with the 18 GHz microwave because the
28 GHz microwave generator was not ready at thattime. Figure 2 shows the beam proﬁle (x-y plot) andhorizontal emittance (x-x′ plot) of 40 Ar11+ beam withthe 18 GHz microwave of 700 W using the PPEM. In
Fig. 2, the beam has a characteristic triangular hollow
shape with widely spread emittance along the horizontal. The triangular shape is formed by the hexapolar
magnetic ﬁeld of the mirror ﬁeld of ECRIS and the ionsare localized into three peripheral regions in the beam.
By selecting one of the three intense regions in the x∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

Fig. 1. New 28 GHz SC-ECRIS and LEBT.

Fig. 2. Obtained beam profile (upper) and horizontal emittance (lower) of 40 Ar11+ beam using PPEM. Color indicates the beam intensity in the arbitrary unit.

y space as a red rectangle in the left of Fig. 2, it isfound that the localization in the emittance space also
appears as shown in the right of Fig. 2. From the result,
we can eﬀectively increase the beam brightness, which
is deﬁned as the beam intensity per unit emittance, bysuitable spatial selection of the localized beam using a
combination of slits and steering magnets.
We plan to ﬁnish the preparations for the 28 GHz microwave generator and high temperature oven to generate metallic vapor in the ﬁrst half of 2019.
References
1) Y. Yano, Nucl. Instrum. Methods Phys. Res. B 261, 1009
(2007).
2) O. Kamigaito et al., Proceedings of IPAC2016, Busan,
Korea, 1281 (2016).
3) T. Nakagawa et al., Rev. Sci. Instrum. 81, 02A320(2010).
4) Y. Higurashi et al., Rev. Sci. Instrum. 85, 02A953(2014).
5) G. D. Alton et al., Rev. Sci. Instrum. 65, 775 (1994).

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Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Development of prototype superconducting linac for low-beta ionsN. Sakamoto,∗1 O. Kamigaito,∗1 K. Ozeki,∗1 K. Suda,∗1 Y. Watanabe,∗1 and K. Yamada∗1
Since 2015, the accelerator group of Nishina Centerhas joined the ImPACT program, led by Dr. Fujita, todevelop a system for processing the so-called long-lived
ﬁssion products (LLFPs) via nuclear reactions and transmutations induced by ion beams provided by a particle
accelerator.1) As a part of this program, a prototype superconducting (SC) linac has been developed. The main
purpose of this prototype is to realize a high accelerationﬁeld gradient Eacc with a high performance SC-cavity(high-Q0 ) and a spatially eﬃcient cryomodule. The cryomodule is the main component of SC-linac, which comprises 4 K SC-cavities. Finally, we tried to evaluate its
stability and reliability using the prototype cryomodule.
The prototype cryomodule (Fig. 1) consists of one SCcavity, one dummy, cavity and a vacuum vessel equippedwith a thermal shield. The length of the cryomodule wasdesigned as 1.34 m. The SC-cavity, whose beam ports
are connected with bellow pipes and are equipped with apower coupler, is supported by four hollow pillars madeof GFRP. To minimize heat conduction from the room
temperature part to the 4 K cold part, a thermal shield isinstalled between the room temperature part and the 4 K
cold part. The thermal shield provides thermal anchors
to the beam pipes, the power couplers, and the cavity
supports.
The developed SC-cavity was based on the structureof a quarter-wave resonator (QWR) (See Fig. 1) with
optimum β as low as 0.08 and a resonant frequency of
75.5 MHz, which can be changed up to 5 kHz with a mechanical tuner. The planned operating Eacc is 4.5 MV/mwith a Q0 of 8.9 ×108 , which is estimated by using the 3D
simulation package Micro Wave Studio (MWS).2) Notethat Q0 is deﬁned as the ratio of its stored energy to the
Vacuum Vessel

4 K Helium Tank

Super Insulator
SC QWR Cavity

4K

Du

m

m

y

Thermal Shield

Bellows

Helium Vessel (Ti)
Magnetic Shield
Acceleration Gaps
Bellows

Bellows

Beam
Gate Valve

Gate Valve

Vacuum Port

Mechanical Tuner

1,340 mmPower Couplers

Fig. 1. Schematic of the prototype cryomodule.
∗1

RIKEN Nishina Center

Target Q0

4K

Fig. 2. Measured Q0 plotted as a function of Eacc .
dashed lines indicate contours of the wall loss.

The

Fig. 3. Power level of the pickup signal (Pt ) from the SCcavity during the long-term operation test.

wall loss of the cavity. The SC-QWR cavity was fabricated using pure niobium sheets. Q0 was measured by anRF(radio frequency) test, cooling the bulk SC-cavity to
4 K with liquid helium. Extensive study of surface treatment was performed3) and a Q0 of 2.3×109 was achievedat an Eacc of 4.5 MV/m (Fig. 2).
After integration of the SC-cavity to the prototype
cryomodule, a long-term operation test was successfully
performed. A solid state ampliﬁer with a maximum output power of 4.5 kW and a digital feedback module havebeen developed, which excite the SC-cavity with an external Q of 1×106 . In the feedback loop, the amplitudeof Eacc was limited by an RF limiter and its phase waslocked to the reference signal provided by the externalsignal generator. The amplitude and phase errors were0.1% and 1 degree, respectively. In Fig. 3, the deviationof the power level of the pickup signal (Pt /Pt0 ) was plotted as a function of the elapsed time during the 12 hr
operation test at an Eacc of 4.75 MV/m. The reliability
with a criteria of |∆Eacc /Eacc | ≤ 0.1%, was evaluated as
95%. This can be improved by tuning the tuner control.
This research work was funded by the ImPACT Program of the Japan Council for Science, Technology andInnovation (Cabinet Oﬃce, Government of Japan).
References

1) http://www.jst.go.jp/impact/en/program/08.html .
2) http://www.cst.com .
3) N. Sakamoto et al., SRF2017, WEYA01; K. Yamada etal., PASJ 14th Annual Meeting, TUOL02.
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Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Performance test of bulk-niobium cavities for new superconducting
linear accelerators
K. Yamada,∗1 K. Ozeki,∗1 N. Sakamoto,∗1 K. Suda,∗1 and O. Kamigaito∗1
In order to upgrade the beam intensity and energy of
the RIKEN Linear Accelerator (RILAC),1) an upgrade
project of the RILAC is now ongoing. The beam intensity is increased by the newly built 28 GHz superconducting (SC) ECR ion source,2) and the beam energy
is boosted over 6.5 MeV/nucleon for ions with mass tocharge ratio of 6 by the new SC linear accelerator (SRILAC).3) The SRILAC consists of three cryomodules including ten SC quarter-wavelength resonators (QWRs)
with a resonant frequency of 73 MHz. The SC-QWRs
are made of bulk niobium and kept at 4.2 K by using alarge liquid-helium refrigerator.
In order to test the performance of SC-QWRs in the
SC state, a test stand was prepared at RIKEN basedon the test stand at KEK.4) We drilled a hole in thefloor and installed a cryostat with an inner diameter of
700 mm and a depth of 3240 mm. A magnetic shield was
put into the cryostat to prevent the penetration of geomagnetism and achieved a value of less than 10 mGauss.
The SC-QWR to be tested is suspended from a flange
and stored in the cryostat as shown in Fig. 1. Liquid
helium is poured into the cryostat until the cavity is
submerged, and the SC-QWR is tested by applying RF
power. X-rays may be generated at high voltage by factors such as field emission of electrons, and the test standis structured to be covered with an iron shield. The validity of the new test stand was confirmed by comparing
the test result of a 73 MHz prototype SC-QWR carriedout in the RIKEN and the KEK.
The performance test of actual SC-QWRs took placefrom June 2018. When the assembly of an SC-QWR wascompleted, the performance test was carried out sequen-

Iron
shieldSC- QWR
Magnetic
shieldFig. 2. Q0 vs Eacc plot of the bulk SC-QWRs. The green
star represents the criteria of the SRILAC.

tially and it was confirmed whether or not acceptableperformance was obtained. In the early days, there wasa problem of vacuum leak of the SC-QWR, but it was
stopped by tightening the flange bolts again. All the SCQWRs were fabricated until November 2018 and tested
immediately. The details of the test procedure are thesame as that given in Ref. 4).
Figure 2 shows the quarity factor Q0 plotted against
acceleration voltage Eacc for all SC-QWRs. Althoughmultipacting was observed at 0.9 MV/m for each SCQWR as indicated in the figure, it could be processed
within a few hours. The test results indicate very highvalues of Q0 and Eacc for all SC-QWRs; thus, all the
SC-QWRs passed the acceptance test successfully. The
maximum Eacc is significantly higher than the required
value, and the exponential deterioration of Q0 has not
yet been observed for all SC-QWRs. Note that the resonant frequency of all SC-QWRs is in the range of thefrequency tuner as expected.
The SC-QWR with which the performance was confirmed was slowly leaked in an ISO class 1 clean room
immediately, the test coupler and vacuum exhaust pipe
were removed, and blank flanges were attached to sendback to the factory for the post-process of installing thetitanium jacket. Currently the SC-QWRs are being installed in the SRILAC cryomodules. The three cryomodules will be completed and allocated in the beginning ofMarch 2019.
References

CryostatFig. 1. Installation of a test assembly by suspending a SCQWR into the cryostat.
∗1

RIKEN Nishina Center

1) M. Odera et al., Nucl. Instrum. Methods Phys. Res. A
227, 187 (1984).
2) T. Nagatomo et al., in this report.
3) N. Sakamoto et al., Proc. of LINAC18, WE2A03, 620(2018).
4) K. Yamada et al., Proc. of LINAC16, THPLR040, 939(2016).

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Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Input power coupler for SRILAC
K. Ozeki,∗1 O. Kamigaito,∗1 N. Sakamoto,∗1 K. Suda,∗1 and K. Yamada∗1
As an upgrade project of the RIKEN Linear Accelerator (RILAC), the construction of a superconducting
heavy ion linear accelerator (Superconducting RILAC,
denoted as SRILAC hereinafter) is now in progress.1,2)
In this report, the progress in the implementation of input power couplers to feed RF power to the resonator isreported.
For the construction of a prototype accelerator system
based on the superconducting quarter-wavelength resonator (QWR),3–9) which was carried out prior to thisproject, the couplers were designed to have double disktype ceramic vacuum windows to ensure the vacuum of
QWR as well as to avoid the long antenna design.10,11)
On the other hand, the couplers for the SRILAC were
designed to have single disk-type ceramic vacuum window, in order to simplify the structure and reduce theproduction cost. The geometry around the vacuum window was designed to have a characteristic impedance of
50 Ω using CST Microwave Studio.12)
The couplers were produced by Mitsubishi Heavy Industries Machinery Systems Ltd. A total of ten couplers
were delivered in sequence. A photograph of the couplers
is shown in Fig. 1.
The couplers must be kept completely clean and degassed in advance in order to prevent contamination of
the QWR. All the operations described below were performed in an ISO class-1 clean room.
At the beginning, the following rinsing operations
were performed: deconstruction of the coupler, rinsing of each part using ultrapure water, drying, and re-construction.
After the rinsing operations, a pair of couplers was
mounted on an RF test stand chamber (see Fig. 2), andthe RF test stand chamber and the two couplers were
baked at 120◦ C.
Then, the ceramic vacuum window was processed withRF power (RF process). Figure 2 shows the setup of the
RF process. While feeding RF power to the system, theinterlocks were set for an emergence of arc light due toa discharge in the coupler, and a loss of vacuum. The
RF process was performed ﬁve times (the two couplers
were processed once), and every time the RF power was
successfully fed up to about 5 kW without any diﬃculty.
After the RF processes were ﬁnished, the couplers
were attached to the QWRs in the ISO class-1 cleanroom. The fabrication of the cryomodules is now inprogress.

Fig. 2. Photograph (left) and schematic (right) of the RF
process. The RF power was fed from the right-side coupler and transmitted to left-side coupler. The left-side
coupler was terminated with a dummy load. The input,
reflected, and transmitted RF powers were measured.

References

Fig. 1. Two sets of input power couplers. Constructed (left)and deconstructed (center and right) parts.
∗1

RIKEN Nishina Center

1) N. Sakamoto et al., in this report.
2) K. Yamada et al., in this report.
3) K. Ozeki et al., Proc. 12th Ann. Meet. PASJ, 1116 (2015).
4) N. Sakamoto et al., Proc. SRF2015, 976 (2015)..
5) K. Ozeki et al., Proc. LINAC16, 598 (2016).
6) K. Yamada et al., Proc. LINAC16, 939 (2016).
7) K. Yamada et al., Proc. 14th Ann. Meet. PASJ, 17 (2017).
8) K. Ozeki et al., RIKEN Accel. Prog. Rep. 51, 131 (2018).
9) N. Sakamoto et al., in this report.
10) K. Ozeki et al., Proc. SRF2015, 1335 (2015).
11) K. Ozeki et al., RIKEN Accel. Prog. Rep. 49, 139 (2016).
12) https://www.cst.com/products/cstmws .

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Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Development of RIKEN 28 GHz SC-ECRIS for the production of
intense metal ion beam†
Y. Higurashi,∗1 T. Nagatomo,∗1 J. Ohnishi,∗1 and T. Nakagawa∗1
At RIKEN, we planned to synthesize new elementswith atomic number (Z) higher than 118, after theexperiments for synthesizing the super-heavy element(Z = 113).1) For this purpose, the production of intense and stable highly charged metallic ion beams, suchas Ti12+, 13+ , V12+, 13+ , and Cr13+ ions, are required.
In particular, there is a strong demand for an intense
beam of V13+ ions to synthesize the new element with
Z = 119. Therefore, we conducted test experiments to
produce these beams and studied the eﬀect of magnetic
ﬁeld distribution to maximize the beam intensity of theseheavy ions for several years.
It is well-known that the “scaling law” 2,3) and the “highB mode” operation4–6) provide some important guidelines to optimize the magnetic mirror ratio of ion sources
for the production of various charge states of heavy ions.
As a ﬁrst step to improve the ion source performance forthe production of these metallic ion beams, we conducteda systematic study to optimize the magnetic ﬁeld distribution using the RIKEN 28 GHz SC-ECRIS7,8) and theliquid He-free SC-ECRIS9) on the basis of these laws. In
the systematic studies, it was concluded that the optimum magnetic mirror ratio (Bext /Bmin ) is 2.2–2.7 for the
production of V13+ ion beam. If we choose Bmin ∼ 0.6 T,
which is the optimum value for the 28 GHz microwave
operation to maximize the beam intensity, the optimum
Bext is predicted to be 1.3–1.6 T. Therefore, we chose
Bext of 1.4 T for the production of V13+ ion beam.
We used a high-temperature oven10) for the production of the V vapor. For long-term operation of the high-Fig. 2. Beam intensity of V13+ ions as a function of microwave power.

temperature oven, we fabricated a new crucible, whose
volume is almost two times larger than that of the oldone.11) To obtain suﬃcient temperature for evaporating
the materials, detailed simulation for optimizing the crucible structure was carefully performed and suﬃciently
high temperature was obtained to produce the vapor.
The detailed results are presented in Ref. 10).
Figure 1 shows the typical charge state distribution ofa highly charged V ion beam at the injected microwave
power of ∼2 kW. The extraction voltage was 12.6 kV.
The ion source was tuned to produce a V13+ ion beam.
The beam intensity increased linearly with increase in
the injected microwave power, as shown in Fig. 2, andobtained ∼400 electric µA of V13+ ion beam with ∼2 kW.
For long term operation (longer than one month), we
successfully produced ∼120 electric µA of V13+ ion beam
without break.
References

Fig. 1. Charge state distribution of highly charged V ions.
†∗1

Condensed from proceedings of ECRIS2018
RIKEN Nishina Center

1) K. Morita, Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016), JPS Conf.
Proc. 14, 010004 (2017).
2) R. Geller et al., Proc. 8th Int. Conference on ECR ion
sources and their applications, NSCL report MSUCP-47(MSU, Dec. 1987), p. 1.
3) R. Geller, Electron Cyclotron Resonance Ion Sources and
ECR Plasmas, Institute of Physics, (CRC Press, Bristol,
1996).
4) T. Antaya, S. Gammino, Rev. Sci. Instrum. 65, 1723 (1994).
5) S. Gammino et al., Rev. Sci. Instrum. 67, 4109 (1996).
6) D. Hitz et al., Rev. Sci. Instrum. 73, 509 (2002).
7) Y. Higurashi et al., Rev. Sci. Instrum. 85, 02A953 (2014).
8) G. Alton, D. N. Smithe, Rev. Sci. Instrum. 65, 775 (1994).
9) T. Kurita et al., Nucl. Instrum. Methods Phys. Res. B
192, 429 (2002).
10) J. Ohnishi et al., Proceedings of ECRIS 2018.
11) J. Ohnishi et al., Rev. Sci. Instrum. 87, 02A709 (2016).

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Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Beam energy adjuster for super-heavy element synthesis at RIKEN
Ring Cyclotron
K. Yamada,∗1 T. Ohki,∗2 H. Yamauchi,∗2 K. Oyamada,∗2 M. Tamura,∗2 A. Yusa,∗2 K. Kaneko,∗2 T. Maie,∗1
Y. Watanabe,∗1 and O. Kamigaito∗1
A new experiment on the synthesis of super-heavy
element (SHE) is on going in the RIKEN Nishina Center using a vanadium beam1) accelerated by the combination of RIKEN Linear Accelerator 2 (RILAC2)2,3)
and RIKEN Ring Cyclotron (RRC).4) For the SHE experiment, the beam energy has to be adjusted to the
pinpoint value that continuously irradiates to a target
over a long period. However, it is diﬃcult to ﬂexibly
change the beam energy by the cyclotron. Therefore,
we introduced a beam energy adjuster (BEA) using an
acceleration cavity into the beam line from the RRC
to the target to ensure that the beam energy can beﬁnely adjusted to approximately ± 3%.
We decided to divert the ﬁnal-stage acceleration cavity, RF power ampliﬁer, and the control system used
as RILAC booster5) to the BEA system. This acceleration cavity is a 6 gap quarter-wavelength resonator.
Although the cell length does not perfectly match withthe velocity of the beam from the RRC, the original
layout of the drift tubes was applicable to the ﬁne adjustment of the beam energy. Because the original resonant frequency of the cavity was 75.5 MHz, it was
remodeled to 73.0 MHz, which was compatible withthe operation frequency of the RRC. To lower the resonant frequency, the outer and inner cylinders were extended by inserting an outer spacer ring and an innerspacer ring, respectively. Both spacer rings were madeof oxygen-free copper. The height of both rings was
36 mm, as determined by 3D electromagnetic calculation using Microwave Studio (MWS). Figure 1 shows
the calculation model of MWS with the spacers.
The original cavity was transferred to the beamdistribution corridor (D-corridor) in the Nishina
Memorial building in the summer of 2017.6) After the
spacer rings were attached to the cavity, a low-power
RF test was performed in October. Figure 2 shows
the inner cylinder of the BEA cavity after inserting
the spacer ring. The test result indicated that it was
successfully remodeled to have a resonant frequencyof 73.0 MHz with a quality factor Q0 of 22500, which
was almost equivalent to the original cavity. The control system, vacuum system, cooling water, and control
cables were installed simultaneously. Finally, the supply and control cables were wired from a high-voltage
power supply located at a power supply building northof the Nishina Memorial building to a tetrode RF ampliﬁer installed at the D-corridor in December. The
high-power RF test was also successfully completed∗1∗2

RIKEN Nishina Center
SHI Accelerator Service, Ltd.

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without any serious problems and the BEA system began operations for the SHE experiment from December
2017.

Fig. 1. A model with spacer rings used in the MWS calculation.

Fig. 2. Inner components of the remodeled cavity.

References
1) Y. Higurashi et al., RIKEN Accel. Prog. Rep. 51, 17(2018).
2) K. Yamada et al., Proc. of IPAC12, TUOBA02, 1071
(2012).
3) K. Suda et al., Nucl. Instrum. Methods Phys. Res. A
722, 55 (2013).
4) Y. Yano, Proc. 13th Int. Cyclo. Conf., 102 (1992).
5) O. Kamigaito et al., Rev. Sci. Instrum. 76, 013306(2005).
6) Y. Watanabe et al., RIKEN Accel. Prog. Rep. 51, 132(2018).

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RIKEN Accel. Prog. Rep. 52 (2019)

Operation of high-temperature oven for 28-GHz superconducting ECR
ion source
J. Ohnishi,∗1 Y. Higurashi,∗1 and T. Nakagawa∗1
Table 1. Summary of MT using HTO.

∗1

RIKEN Nishina Centermaterial

consumption
rate (mg/h)

34

UO2

2.4

35

UO2

3.2

UO2

4.0, 4.2, 12

periodU35+

10–11/2016

100–120

U35+

5–6/2017

60–120U35+

10–11/2017

80–1207 + 27 + 10

U35+

10–12/2018

110–140

27.5 + 30

UO2

2.4, 2.4

V13+

1–2/2018

100–210

20 + 13

metal V

2.2, 4.1

V13+

6–7/2018

100–230

23 + 9metal V

2.0, 3.8V13+9/2018

90–11010

metal V

2.4

890

U35+ beam current
oven current
power

160
140

860
830

120

800

100

770

80

740

60

710

40

680

20

650

0

10/7

10/17

10/27

11/6

11/16
date

11/26

12/6

Current (A) / Power (W)

180

620
12/16

Fig. 2. Operational trend of HTO in U-MT of 2018.

beams are not supplied to the accelerators and change
according to the width of the slits located upstream.
This trend shows that uranium beams of 120 μA or
more could be supplied stably except during the last two
weeks mentioned below. The power of heat generationof the crucible was obtained by subtracting the Jouleloss on the support pipes from the total electric power.
The operation of the ion source was interrupted because
the crucible was changed to a new one for replenishment
of UO2 on Nov. 9. Although stable operation was performed, we had to increase the current and power of the
HTO after the end of November, as can be seen in theﬁgure. The reason was because a vapor-ejection hole ofthe crucible was blocked by a pileup of UO2 and thebeam intensity decreased. The ﬁrst blockage that happened on December 6 was resolved naturally and the MT
ended as scheduled even though the second blockage occurred. It was found that blockage tends to occur when
the amount of vapor is large. This problem is serious,
but it has not been solved yet. Details of this article areshown in Ref. 3).
References

Fig. 1. Schematic of the tungsten crucibles.

beam
operation
current (PA) time (d)ion

U35+ (μ A)

Uranium beams, which are accelerated at the RI-beam
Factory (RIBF), are extracted from a 28-GHz superconducting ECR ion source (SC-ECRIS)1) by using ahigh-temperature oven (HTO). Our HTO uses a tungsten crucible, which is joule-heated with a DC current of
600–700 A. Figure 1 shows the dimensions of two typesof crucibles. The crucible is heated to approximately
2000◦ C in order to achieve a UO2 vapor pressure of 0.1–
1 Pa. The HTO, which has been under development
since 2013,2) was ﬁrst used to operate the ion source for
the RIBF experiments in the autumn of 2016.
The HTO was also used to produce high-intensity
vanadium beams in the 28-GHz SC-ECRIS. V13+ beams
with a current of 100 μA or more were supplied tothe beam time for experiments on super heavy element
synthesis from 2018. For the production of vanadium
beams, we placed a yttria crucible into a tungsten crucible and ﬁlled it with metal vanadium (vapor pressure:
1 Pa at 1827◦ C) because the metal vanadium should beelectrically insulated from the crucible.
Table 1 lists a summary of the machine-time (MT),whose beams were supplied from the 28-GHz SC-ECRIS
using the HTO. Four uranium-MT (U-MT) and three
vanadium-MT have been performed so far. During normal operation, the average currents of U35+ and V13+
were both approximately 100–120 μA. The HTO can be
operated continuously for at least three weeks because
the ﬁllable amount of the R692 type, which was used forthese MTs, was approximately 2 and 4 g for vanadiumand UO2 , respectively.
Figure 2 shows the trend of the beam current of U35+ ,the electric current, and the power of heat generation of
the crucible during the U-MT in the autumn of 2018.
The beam current of U35+ was measured with a Faraday cup positioned down-stream of the analyzing magnet. The beam current can only be measured when the1) Y. Higurashi et al., Rev. Sci. Instrum. 85, 02A953 (2014).
2) J. Ohnishi et al., Rev. Sci. Instrum. 87, 02A709 (2016).
3) J. Ohnishi et al., Proc. 23rd Int. Workshop on ECR ion
sources, Catania Italy, Sep. 2018, to be published in JACOW Web site.

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RIKEN Accel. Prog. Rep. 52 (2019)

Laser Energy Dependence of Plasma Instability by Solenoid
Magnetic Field†
T. Karino,∗1,∗3 M. Okamura,∗1,∗2 T. Kanesue,∗2 S. Ikeda,∗2 and S. Kawata∗3
A very high current beam is required for heavy-ion
inertial fusion (HIF), and therefore the use of a laser
ion source using a solenoid is proposed. By using asolenoid magnetic field, the spread of plasma can besuppressed. However, it has been found that a certain range of field strength triggers unstable plasma
condition.1)
Figure 1 shows the experimental setup. The plasma
generated by the laser on the target is measured by a
Faraday cup after it is transported through a 3000 mm
long solenoid coil located 315 mm from the target.
Nd:YAG laser was used with an incident angle of 20◦ .
Figure 2 shows the example of Au target when thelaser energy is 411 mJ. The vertical axis and horizontal
axis show the beam current and time of flight, respectively. In the figure, waveforms of the beam current for
40 shots are overlaid on each other. Figure 2 (a) shows
the case without the solenoid. Figure 2 (b) shows thecase when the solenoid magnetic field is 28.6 G. It isfound that the waveform of Fig. 2 (b) is more unstable
than the waveform of Fig. 2 (a).
Figure 3 shows the experiment result of the Au target. The vertical axis represents the instability of theplasma, and the horizontal axis represents the solenoid
magnetic field. In this experiment, the plasma instability was evaluated based on the standard deviationof the half width over peak current. By using thismethod, it is possible to know the degree of collapseof the waveform. In Fig. 3, the larger the value on
the vertical axis is, the more unstable the plasma is.
The energy of the Nd: YAG laser was 312 to 411 mJ.
The laser spot size was 3.84 mm. From Fig. 3, it canbe seen that the range of the magnetic field where thebeam current becomes unstable varies depending on
the laser energy.
Moreover, it was found that the unstable rangechanges also when the target is changed from anotherexperiment. For example, in the case of Fe, the magnitude of the solenoid magnetic field where the plasma
became unstable became smaller than that of Au.
From these experimental results, it can be said thatthe unstable range of plasma varies with the speed andtype of plasma.

Fig. 2. Waveform of current beam (Laser energy is 411 mJ).

Fig. 1. Experimental equipment.
†

∗1
∗2
∗3

Fig. 3. Experiment result of gold target.
Condensed from the proceedings HIF 2018
RIKEN Nishina Center
Collider-Accelerator Department, Brookhaven National
Laboratory
Graduate School of Engineering, Utsunomiya University- 110 -

Reference
1) K. Takahashi et al., AIP Conf. Proc. 1525, 241 (2013).

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RIKEN Accel. Prog. Rep. 52 (2019)

Evaluation of beam orbit calculation method for the injection line of
AVF cyclotron and performance evaluation of pepper-pot emittancemonitor∗1
Fig. Sakemi,
2.
Y. Kotaka,∗1 Y. Ohshiro,∗1 H. Yamaguchi,∗1 N. Imai,∗1 Y.
T. Nagatomo,∗2 M. Kase,∗2 J. Ohnishi,∗2∗2∗3∗4
A. Goto, K. Hatanaka, H. Muto, and S. Shimoura∗1

We ﬁnished developing a calculation method forthe beam orbit from the Hyper ECR ion source tothe center of the AVF cyclotron using the 4D emittance measured with a pepper-pot emittance monitor1)(PEM_IH10).2,3) We attempted to numerically evaluate our calculations of 15 types of beams by comparing
other diagnostics.
To evaluate our beam orbit, we compared it to the2D emittance measured by the 2D emittance monitor4)(EM_I36) installed 6.2 m away from PEM_IH10 using
χ2 test. However, it should be noted that the 1D distribution projected from the 2D distribution was used
for the comparison. χ2 is deﬁned as the sum of squared
diﬀerences of each position or each angle between themeasurement and the calculation divided by an assumed
dispersion. However, this value itself is not signiﬁcantbecause this experiment was conducted to observe therelative variations in the results. This value was estimated so that χ2 /DOF becomes approximately 1 when
the calculation may conform to the measurement by visual judgement.
4D emittance was measured using a standard (x, y)
coordinate system perpendicular to the beam direction,
where x and y denote the horizontal and vertical directions, respectively. The coordinate system of EM_I36(u, w) was rotated by 45 degree against the (x, y) coordinate system, and u’ and w’ were the angles of u-axis
and w-axis, respectively. The left part of Fig. 1 indicatesthe scatter plot of χ2 /DOFs of u and u’. The χ2 /DOFs
of w and w’ is indicated in the right part of Fig. 1. The
displacements in the position or angle between the measurement and calculation were determined but they werecanceled to determine the distribution conformity in thiscomparison.
All values of χ2 /DOF were is found to be
Fig. 1.
scattered up to 6. The reasons of this variation are being

Fig. 1. (left) Scatter plot shows χ2 /DOFs of u and u’. (right)
Scatter plot shows χ2 /DOFs of w and w’. Fifteen beams(H+ , D+ , 4 He2+ , 7 Li2+ , 11 B4+ , and 18 O6+ ) are tested.
∗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

Δy (mm)Δx (mm)x (mm)y (mm)

Fig. 2. Diﬀerences in distribution between ﬁducial points andmeasured position on pixel coordinate: x-axis (left) andy-axis (right).

examined singly.
The above-mentioned displacements for positions andangles were approximately 10 mm and 10 mrad, respectively. One of the considerable reasons is the magnetic hysteresis of the vertical deﬂection dipole magnet (DMI23). We measured the magnetic hysteresisand found the magnetic diﬀerence to be 1.7% when
the commonly-used excitation current varied from 10 to
20 A. For example, 1.0% magnetic ﬁeld diﬀerence is estimated to cause 10 mm diﬀerence at 300 mm from DMI23
when the excitation current is 25 A. Because we used asetting excited current for the beam orbit calculation
without knowing this, these displacements in positions
and angles occurred. Therefore, the magnetic ﬁeld of
DMI23 needs to be measured.
After the beam orbit calculation, we started the performance evaluation of PEM_IH10 for improvement andfocused on the position error of the ﬂuorescent plate. As
its view was recorded by the digital camera, it transformed to real space by the relationship between theﬁducial points on the ﬂuorescent plate and their measured positions on the pixel coordinate. The position error was estimated from the diﬀerences between the ﬁducial points and their transformed positons. Previously,
there were 15 ﬁducial points with a diameter of 1 or
2 mm. The standard deviations (SD) of the diﬀerencesof x direction and y direction were 0.12 and 0.19 mm,
respectively. For improvement, we used a graph paper
pasted on the ﬂuorescent plate and selected 225 ﬁducial
points at 5 mm interval in the area of 70 mm square.
The diﬀerences in the distributions of x and y are shownin the left and the right parts of Fig. 2, respectively. The
SD of diﬀerences of x and y were improved to 0.06 and0.07 mm, respectively. Other performance evaluation
will be conducted.
References

1) T. Hoﬀmann et al., AIP Conf. Proc. 546, 432 (2000).
2) Y. Kotaka et al., Proc. 14th Annual Meeting of PASJ,(2017), pp. 1118–1122.
3) Y. Kotaka et al., RIKEN Accel. Prog. Rep. 51, 138 (2018).
4) Y. Kotaka et al., RIKEN Accel. Prog. Rep. 41, 96 (2008).

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RIKEN Accel. Prog. Rep. 52 (2019)

Updating control units around the AVF cyclotron
M. Komiyama,∗1 M. Fujimaki,∗1 N. Fukunishi,∗1 R. Koyama,∗2 M. Hamanaka,∗2 H. Mukai,∗3 T. Nakamura,∗2 andA. Uchiyama∗1
We report on the update of the control units aroundthe AVF cyclotron to reduce the diﬃculties caused by radiation and implement a new beam interlock system under construction (hereafter, AVF-BIS). The beam diagnostic equipment like a beam proﬁle monitor or a Faraday cup on the AVF cyclotron and its beam transportline has been controlled by DIM1) since 1989, and theequipment on the beam transport line around RILAC2
has been controlled by N-DIM2) since 2012. They were
installed in 19-inch racks (hereafter, rack) at two place:the ﬂoor on which the AVF cyclotron is placed (hereafter, AVF ﬂoor) and the ﬂoor that is one level below(hereafter, AVF-M2 ﬂoor). Recently, as the performanceof the AVF cyclotron has been improved and the beam
intensity accelerated by the AVF cyclotron has been increased, there have been frequent issues such as the control unit becoming unresponsive toward the remote control suddenly. In the most frequent case, it occurred
three times in 4 h while accelerating a 12 MeV/nucleon
deuteron beam with an intensity of 4 pµA at the C03
target. Because this frequently occurs during accelerating a deuteron in the AVF cyclotron, we speculatethat the cause of the trouble is the inﬂuence of radiation, especially the neutrons coming out from the
AVF cyclotron and its beam transport line during beamtransport. Therefore, we measured the dose of neutron
around the installation location of the control unit using the TL badge. Figure 1 shows the measurement
locations and results of the two measurements. At the
AVF-M2 ﬂoor, several racks are placed along the south
wall for the control unit. Among them, the control unit
where this issue frequently occurs is located at No. 1 inFig. 1. The results clearly show that the neutron doseat this point is higher than other places. This might beoccurring because No. 1 is close to the open hole underthe AVF cyclotron (No. 9). However, it has not been
speciﬁed yet. As the best measure at present, we moved
the control unit to a place where the neutron dose was
low based on the results.
Simultaneously, we updated the control unit from old
DIM to N-DIM. This update was made because the DIM
in use was old and the DIM-based existing beam interlock system for the AVF cyclotron needed to be renewed
along with its low-energy experimental facility to AVFBIS.3) AVF-BIS stops a beam by outputting signals toa beam chopper and Faraday cup for various interlock
signal inputs. In this system, the Faraday cup needs tobe controlled by N-DIM.
The updating work was conducted during the summer
maintenance period in 2018 as follows:
∗1

∗2
∗3

RIKEN Nishina Center
SHI Accelerator Service Ltd.
Japan Environment Research Corporation

Fig. 1. Neutron dose measurement. The AVF-B2 floor is one
floor below the AVF-M2 floor. The data written on theright side shows the average dose (integrated dose).

(1) To move one of the racks from No. 1 to No. 3 with
the N-DIM inside.
(2) To move some N-DIMs mounted on the rack next
to the rack to be relocated to the gap between theexisting racks near No. 3.
(3) To set up some new N-DIMs on the existing racks
near No. 3. Remove the signal and control cablefrom the DIM at No. 3 and AVF ﬂoor, and reconnect them to the newly set up N-DIMs.
Consequently, we moved and set up 28 N-DIMs in total. Currently, they control the beam diagnostic equipment on the beam transport line around RILAC2, andthe beam diagnostic equipment and vacuum system on
the beam transport line downstream of AVF cyclotron.
This indicates that approximately 60% of the DIMs under operation at the AVF and AVF-M2 ﬂoors have been
updated. Because DIM still controls the various equipment attached to the AVF cyclotron and the beam diagnostic equipment of the beam transport line in E7 experimental vault, we are planning to sequentially update
the control to N-DIM.
After the summer maintenance, the occurrence of thisissue in the control unit was reduced to 0% while accelerating the 12 MeV/nucleon deuteron beam with an intensity of 1.5 pµA at the C03 target for more than one
month. Thus, it is evident that this maintenance has
had certain eﬀect.
References
1) K. Shimizu et al., Proc. Cyclotrons’84, pp. 392–395.
2) M. Fujimaki et al., RIKEN Accel. Prog. Rep. 37, 279(2004).
3) M. Komiyama et al., Proc. ICALEPCS2017, (2017),
pp. 427–430.

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RIKEN Accel. Prog. Rep. 52 (2019)

Reconstruction of RF system controller for RIKEN Ring Cyclotron
K. Yamada,∗1 S. Fukuzawa,∗2 M. Hamanaka,∗2 S. Ishikawa,∗2 K. Kobayashi,∗2 R. Koyama,∗2 T. Nakamura,∗2
M. Nishida,∗2 M. Nishimura,∗2 J. Shibata,∗2 N. Tsukiori,∗2 K. Yadomi,∗2 K. Suda,∗1 and N. Sakamoto∗1
The RIKEN Ring Cyclotron (RRC) has been supplying beams for various experiments as the key accelerator of RIKEN Nishina Center for over 30 years.
The RRC has two sets of acceleration cavities and RF
power amplifiers,1) and each set is controlled by an independent controller system. Most controllers of the
RRC’s RF system consist of hardware logic using relays and analog transmission to/from low-level circuits
and analog meter. Equipment for RF voltage setting,
RF phase setting, drivers of frequency tuners and RF
power coupler, and drivers of RF matching circuits
for amplifier were controlled by independent control
boxes for each device. A programmable logic controller(PLC) was used for the indicator control and remote
operation interface, and it was replaced in 2004 without changing the system configuration. By updating
the low-level circuits in 2007, the analog voltage outputs from the RF voltage and phase setting boxes wereconverted to digital signals by additional converters
and connected to the new low-level circuits. The data
logging system did not work because it was old andoutdated. The previous hardware type control system
could not freely set operation parameters like the frequency tuning system, which caused significant interruption in the machine time. To solve such inconveniences, we decided to update the system that can be
integrated and controlled by a PLC.
The new system is controlled by the Mitsubishi Electric MELSEC-Q series PLC and a touch panel forhuman-machine interface. Figure 1 shows images ofthe main part of the original control rack and updated
control rack. The low-level circuits were transferredfrom the RRC room to the underground passage andintegrated into the PLC control rack, as shown in theright panel of Fig. 1, and controlled directly by the
PLC. Power supplies for the tetrodes in the RF amplifier were also controlled directly by the PLC. We replaced the all old signal transducers of the filament andplate power supplies as well as the power supplies forgrid electrodes. The old two-phase stepping motors forthe two movable boxes, trimmer, and RF power coupler were replaced with a new five-phase stepping motor, SANYO DENKI FSF893S, which can set parameters such as the driving speed. The remote operationof the system was integrated into the operation terminal of RILAC22) through Ethernet using the SCADA
software of Wanderware InTouch. The operations of
RF voltage and phase were also integrated into theoperational interface3) using rotary encoders through∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

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the CC-Link slave interface, Anywire AFCS02.
The control system for RRC’s RF was successfully
updated in March 2016. Owing to these modifications, several improvements were obtained. The timeof RF re-excitation when discharged was curtailed from30 min to a few minutes. The RF voltage was enhanced by more than 10% by the assured automatic
re-excitation function. The amplifier damage at the
RF voltage trip was significantly reduced by the voltage rump-up function. The resolutions of RF voltage
and phase set points were improved from 1/10000 to
1/30000 and 1/36000, respectively. The control system
upgrade contributed to the stabilization of beam operation during the RIBF experiment and further performance improvement is expected in combination withthe cavity upgrade of RRC reported in Ref. 4).

(a)

(b)

Fig. 1. Main part of control system before (left panel) andafter (right panel) the upgrade.

References
1) T. Fujisawa et al., Nucl. Instrum. Methods Phys. Res.
A 292, 1 (1990).
2) K. Yamada et al., Proc. of IPAC12, TUOBA02, 1071
(2012).; K. Suda et al., Nucl. Instrum. Methods Phys.
Res. A 722, 55 (2013).
3) K. Yamada et al., RIKEN Accel. Prog. Rep. 49, 150(2016).
4) K. Yamada et al., in this report.

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RIKEN Accel. Prog. Rep. 52 (2019)

Radiation monitoring for cycrotrons in RIBF
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) Usually, we investigate the radiation from theelectrostatic deﬂection channels (EDC) at RRC and
SRC. We input the alarm signal from these ICs to thebeam interlock system (BIS).2,3) However, four ring cyclotrons RRC, fRC, IRC, and SRC are used in the caseof 238 U86+ beam acceleration. Hence, we installed theICs near the EDC of fRC and IRC. Last year, we conducted tests by inputting the alarm signal from the IC
signal near the EDC of the IRC. In this report, we attempted to input the alarm signal from the IC near the
EDC of fRC to BIS.
We considered the alarm levels of the ICs by comparing the signals from the ICs with those from the thermocouples (TCs) set at the septum of RRC, IRC, andSRC.2,3) Suppose that a beam deposits a 600 W heatat the septum electrode of the EDC. The temperaturerise at the beam loss point is estimated to be 800◦ C
based on a thermal analysis using the ﬁnite element
method. At this moment, the temperature diﬀerence
between the TC set at the nearest part where the beam
was irradiated and the cooling water of the septum becomes 10◦ C. In contrast, the septum is made of Cu andits melting point is 1080◦ C. Therefore, the septum cannot be melted at these conditions. However, to protect
against the risks of damage caused to the septum, thealarm level of the temperature diﬀerence of TCs was
set to 10◦ C. Hence, we compared the temperature difference on the septum with the IC signal near the EDC
of fRC in the user time (UT) of the 238 U86+ beam. The
result is shown in Fig. 1. The data demonstrated little
dispersion and we can obtain a calibration curve (redline), as shown in Fig. 1. From this curve, we can recognize that the voltage of the IC became approximately
0.55 V when the temperature diﬀerence became 10◦ C.
From October 16 to December 16, the 238 U86+ ion
beam was accelerated to 345 MeV/nucleon. Usually,
we collected the data of TCs and IC within 7–10 days
from the beginning of the UT of RIBF. Based on thisobservation, we determined the alarm level of IC and
set it to BIS, which is the time available between thisexperiment and the next. However, in this term, we
could not ﬁnd any vacant time to input the alarm signal
to BIS. Thus, we compared the data when the BIS acted
on the signal from the TCs set at EDC of fRC withthe data of IC set near the EDC of fRC. We can thenconsider the propriety of the alarm level of the IC signal.
The IC signal from 0:00 to 5:00 on 12/3/2018 isshown in Fig. 2 as typical example data. From 2:08
to 2:50, BIS acted 20 times by the sudden temperaturerising of EDC for the instability of electric ﬁeld of fRC.
∗1

Fig. 1. Correlation of IC voltage and the temperature difference on the septum.

Fig. 2. Signals from the IC installed near the EDC of fRC.

During this term, the value of IC set near the EDC
distributed from 0.56 to 1.05 V. Such phenomena were
frequently observed on other days of this UT. On observing the IC signals when the BIS from TCs signals
acted in this UT, the alarm level of IC described above
is found to be reasonable.
We performed investigations by inputting the alarm
signal to the BIS during the machine time of the238 86+U
ion beam. However, we could not input thesignal from the IC set near the EDC of fRC. Hence, wewill investigate the alarm signal from fRC to BIS nexttime.
References
1) M. Nakamura et al., RIKEN Accel. Prog. Rep. 50, 152(2017).
2) M. Nakamura et al., RIKEN Accel. Prog. Rep. 49, 146(2016).
3) M. Nakamura et al., RIKEN Accel. Prog. Rep. 48, 237(2015).

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Development of beam interlock system driven by change in current of
the magnet
K. Kumagai∗1 and A. Uchiyama∗1
At the RI Beam Factory, the machine time (MT) using
SRC (Superconducting Ring Cyclotron) is implemented
for about 4 months a year. In recent years, with increasein the beam intensity, the power of the beam at the target has increased to about 13 kW during 78 Kr acceleration. Many electromagnets used in cyclotrons and beamtransport lines are individually powered by a DC power
supply. When the power supply fails, the trajectory of
the beam changes. If the beam strikes the vacuum vessel and melts, the beam operation cannot be continued.
To prevent such troubles, when the power supply fails orturns oﬀ, the power supply itself detects this and sends
a signal to the beam interlock system (BIS),1) and stops
the beam within a few tens of milliseconds. On the other
hand, even when the power supply is in operation, if thecurrent value changes arbitrarily, the beam trajectory
will change and cause trouble. Such abnormal events do
not occur frequently, but several troubles have occurred.
For example, during the 70 Zn-MT on April 18, 2017,
the current value of the SRC-SH1 power supply changed
from −24 A to −97 A without any operation. The beam
struck the vacuum bellows at the SRC injection section,
the bellows melted, and the MT was interrupted.
With the increase in beam power, it becomes necessary to have a system that stops the beam by detecting
the changes in current due to unknown causes or noises.
A simple method is to constantly measure the set current value of the power supply and the actual current
through the network, and when the diﬀerence between
the two values become large, the system issues a signal.
However, with the method of monitoring via the network, it is diﬃcult to stop the beam within a few tensof milliseconds after the phenomena, since the repetition
rate of the monitor is not suﬃciently fast and the monitoring speed cannot be kept constant.
Therefore, we developed a system that can detectchanges in the current of the power supply by a relatively
simple method and send a signal to the beam interlock
system only when it is not due for operation. Figure 1
shows a schematic diagram of the beam interlock system driven by change in current (Curs-BIS). The system
consists of an FA-M3 PLC produced by Yokogawa Electric Corp. The main components are a sequence CPU,
analog input modules, and a digital output module.
In order to precisely measure the current stability, thesignal cables had already been wired from each power
supply to the DVM. The signal cables are branched andconnected to the 16-bit analog input modules in theCurs-BIS system. The system is programmed to measure the input analog signals of 24 to 48 points at intervals of 8 msec and send a signal to the beam interlock
system when the measured value exceeds the preset allowable value. On the other hand, when the current is∗1

RIKEN Nishina CenterFig. 1. Schematic diagram of the beam interlock system
driven by change in current (Curs-BIS). The parts drawn
in red are newly installed.

changed by an operation for the adjustment of the beam
trajectory, the signal should not come out. In order todistinguish whether the change in current value is due tothe operation or not, a real-time CPU module (F3RP61)
that was installed Linux was added.2) Since the EPICS
CA client runs on the CPU, when the power supply operation is performed on the EPICS network, the information can be detected within several milliseconds andis instantaneously transmitted via the FAM3 bus to thesequence CPU register. Thus, a program is establishedto judge whether the change in current is due to an operation or some kind of trouble and judge whether tosend a beam interlock signal. After the current has beenchanged by the operation, the allowable range of current
is automatically reset again after several tens of seconds.
The time required for one scan of the sequence program was about 0.4 msec during normal operation. All
the current values that are being measured and the histories of the beam interlock signal can be monitored on
the WEB.
We tested two sets of the Curs-BIS at uranium machine time from October 2018. The number of power
supplies monitoring the current was 24 units each. The
power supply stopped due to trouble several times, andthe change in current was detected and the system
worked correctly. The result of the test was almost satisfactory. However, unnecessary interlock signals weresometimes issued when some of the power supplies werelargely changed from 0 A to a predetermined current
value.
Next time, we will improve the program so that no
signal will be issued just after the power supply is turned
on. In addition, we will also increase the number ofmonitors to 48 per units.
References

1) M. Komiyama et al., RIKEN Accel. Prog. Rep. 39, 239(2006).
2) A. Uchiyama et al., Proc. PCaPAC08, WEX03, (2008).

- 115 -

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Design of reliable control with star-topology fieldbus communication
for an electron cyclotron resonance ion source at RIBF†
A. Uchiyama,∗1 T. Nagatomo,∗1 Y. Higurashi,∗1 J. Ohnishi,∗1 T. Nakagawa,∗1 M. Komiyama,∗1 N. Fukunishi,∗1
H. Yamauchi,∗2 M. Tamura,∗2 and K. Kaneko∗2
A new superconducting electron cyclotron resonanceion source (SC-ECRIS) was installed at RILAC in the
RIKEN project to increase the beam intensity.1) Considering the new SC-ECRIS, the control system should
follow the current RIKEN 28-GHz SC-ECRIS control
system for RILAC2, because the RIKEN 28-GHz SCECRIS control system based on Experimental Physics
and Industrial Control System (EPICS) has proven tobe successful.2) Thus, in the new SC-ECRIS control
system, we adopted a programmable logic controller(PLC) of the Yokogawa FA-M3V series.
However, the RIKEN 28-GHz SC-ECRIS control
system is less reliable because it uses TCP/IP communication between the PLC controllers for interlock signal. In general, a network I/O-based interlock system
is not highly reliable owing to the failure of network
switch in the network route and slow signal transmission speed as compared to the bus access. Therefore,
the reliability of a signal through TCP/IP is lower thanthat of an electric signal, which results in a less reliableinterlock.
Accordingly, to overcome this disadvantage, a new
SC-ECRIS control system has been designed by implementing two diﬀerent types of CPUs in the main PLC
station. Essentially, the sequence PLC CPU (F3SP71)
in the ﬁrst slot and Linux PLC CPU (F3RP61) in thesecond slot have been implemented in the same PLC
base module. In the sequence PLC CPU, the sequential program called ladder program runs for the interlock system and the Linux CPU runs the EPICS
input/output controller (IOC) and provides operation
services to users via the EPICS Channel Access protocol. In the Yokogawa FA-M3V series, the ﬁeldbus iscalled the FA bus. The controllers on the main station
manage four substations connected through FA bus
communication, electrically isolated by optical ﬁbers.
Because the heavy ions generated by an ion source are
extracted to the low-energy beam transport by highvoltage, substations also need to be implemented at thehigh-voltage stage in some cases. The new SC-ECRIS
control system consists of a main PLC station and ﬁve
PLC substations with star-topology ﬁeldbus communication using optical FA bus modules (see Fig. 1).
At present, this control system does not include thecontrol for superconducting electromagnet power supplies. The system has been implemented by another†∗1∗2

Condensed from the article
No. WEP30
RIKEN Nishina Center
SHI Accelerator Service Ltd.

in

Proc.

PCaPAC2018,- 116 -

Fig. 1. System chart of new SC-ECRIS control system. Interlock signal is delivered by bus communications.

PLC with EPICS.
This new SC-ECRIS control system was successfully
used in the test operation of the new SC-ECRIS performed in August 2018 without any serious problem.
Because two CPUs were mounted in one base unit, thetrigger signal could be exchanged for interlocking withthe sequence PLC CPU from the Linux PLC CPU via
the FA bus on the PLC base module. Therefore, it
is possible to share the interlock signal of the highvoltage stage with the Linux PLC CPU and sequence
PLC CPU without going through the TCP/IP network, which improves the system reliability of the interlock feature successfully without lowering the conventional system usability.
References
1) T. Nagatomo et al., in these proceedings.
2) M. Komiyama et al., Proc. ICALEPCS 2009, (2009),
pp. 275–277.

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Operation report for Nishina and RIBF water-cooling systems
T. Maie,∗1 K. Kusaka,∗1 M. Ohtake,∗1 Y. Watanabe,∗1 E. Ikezawa,∗1 M. Oshima,∗2 H. Hirai,∗2 K. Kobayashi,∗3
A. Yusa,∗3 and J. Shibata∗3
Operation condition
In FY 2018, the cooling systems in Nishina and
RIBF were operated for approximately same periods
as the accelerators. As the experiments of GARIS II
in E6 room had begun, RIBF’s cooling systems wereoperated for approximately two-and-a-half months,
which was slightly shorter [than usual]. Nishina’s cooling systems’ which consisted of AVF-stand alone and
AVF + RRC were operated for approximately sevenmonths. There was no significant issue to cause interruption of accelerator operation’ and the cooling systems were operated almost steadily except some of minor problems.
Trouble report
The problems of the cooling systems as follows;
Burst of frozen cooling piping in the cooling tower in
February 2018 due to the decrease of outside temperature, Malfunctioning of the inverter used for the watercooling pump caused by aging degradation, Malfunctioning of the control valve.
Periodic maintenance(1) Cleaning of the cooling towers(2) Inspection and overhauling of the water- coolingpumps(3) Inspection of the inverter for the RIBF watercooling pumps(4) Inspection and overhauling of the air compressor(5) Replacement of some superannuated hoses,
joints’ and valves used in the system(6) Cleaning of the strainers and filters used in thedeionized water production system(7) Extension of the sensing wires of the water leakage alarm to floors of new areas(8) Switching electricity during planned power failure as well as restoration of each device(9) Securing of minimum power at low load operatorof CGS (cogeneration system)
Establishment and improvement
In this fiscal year, it has been planned that four systems of the RIBF cooling tower’ whose performanceswere degradated by aging’ are to be overhauled on a
∗1

∗2
∗3

RIKEN Nishina Center
Nippon Kucho Service Co., Ltd
SHI Accelerator Service Co., Ltd- 117 -

Fig. 1. Photographs of the four systems of RIBF cooling
tower overhaul and new cooling systems for RILAC’s
super conductive.

large scale, new cooling systems are to be installed
along with RILAC’s superconductive, and constructionof RRC cooling systems for rainforcement of cooling
capacity and for stabilization of cooling water temperature. The constuction of the RRC cooling systems
mentioned above is aimed at elimination of the fluctuation of the magnetic field of an RRC electromagnet
due to the inconstancy of the cooling water.
References
1) T. Maie et al., RIKEN Accel. Prog. Rep. 51, (2017).
2) T. Maie et al., RIKEN Accel. Prog. Rep. 50, (2016).

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Pressure measurement of plasma window with large diameter
N. Ikoma,∗1,∗2 Y. Miyake,∗1 M. Takahashi,∗1 H. Okuno,∗1 S. Namba,∗3 and T. Kikuchi∗42

10

P1 [kPa]

The plasma window (PW),1) which separates a vacuum from an atmosphere by an arc plasma ﬁlling thedischarge channel, is a novel beam window technology. It has several applications in an accelerator system such as a gas charge stripper2,3) for a heavy ion
accelerator or a beam window for an accelerator-driven
subcritical reactor (ADS).4) In addition, a target system using PW has been proposed in the ImPACT Fujita program5) for the transmutation of long-lived ﬁssion products (LLFP) into a stable or short-lived nuclei. However, the small diameter of PW is a crucial
problem for these applications. The ﬁrst PW invented
by Hershcovitch,1) with an aperture of 2.36 mm, aimed
at electron beam welding in an atmosphere. However,the beam spot size in our intended case is several tensof millimeters or more. Therefore, to implement thePW in the accelerator system, its diameter needs tobe enlarged. Furthermore, an investigation of the relation between conﬁnement pressure and diameter isalso important to predict the performance of PW forvarious purposes. Therefore, we have developed a PW
with large diameter in reference to a PW designed by
Namba et al.6) In a previous study,7) we reported theperformance of a PW with a diameter of 10 mm. After that, we systematically measured the pressure byvarying the diameter from 6 to 20 mm. In this study,
the preliminary results of pressure measurement havebeen reported.
The experimental setup is shown in Fig. 1. Argon
gas was introduced from the upstream of the PW. It
was then exhausted by two mechanical booster pumps(Edwards, EH 500, the exhaust speed of each pump
was approximately 100 L/s). Three DC power sup-

101

100

0

∗1
∗2
∗3
∗4

RIKEN Nishina Center
Department of Energy and Environment Science, Nagaoka
University of Technology
Graduate School of Engineering, Hiroshima University
Department of Nuclear System Safety Engineering, Nagaoka
University of Technology- 118 -

10
15
Diameter [mm]2025Fig. 2. Dependence of P1 on the diameter of PW.

plies (TDK Lambda, ESS-400-37-2-D) were connectedin parallel between the cathode and anode, and an arc
current of 100 A was supplied. The discharge voltage
was monitored by a data logger (KEYENCE, NR-600).
The gas ﬂow rate was maintained at 20 L/min by themass ﬂow controller (MKS Instruments, 1579 A) andboth upstream and downstream pressures, P1 and P2 ,were measured.
Figure 2 shows the upstream pressure P1 on each diameter, which decreased with an increase in the diameter of PW. P2 was maintained at approximately 200 Pa
in each condition. These results will be compared withthose of an existing theoretical model (P1 ∝ 1/r2 )based on viscous laminar ﬂow.8,9) We will determine
a prediction model that can describe the conﬁnement
pressure in the PW with a large diameter.
This work was supported by RIKEN Junior Research Associate Program and funded by ImPACT
Program of Council for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
References

Fig. 1. Experimental setup.

51) A. Hershcovitch, J. Appl. Phys. 78, 5283 (1995).
2) H. Okuno et al., Phys. Rev. Accel. Beams 14, 033503(2011).
3) H. Kuboki et al., J. Radioanal. Nucl. Chem. 299, 1029
(2014).
4) S. Ben-Liang et al., Chin. Phys. C 38, 018201 (2014).
5) Impulsing Paradigm Change through Disruptive Technologies Program ImPACT, http://www.jst.go.jp/
impact/en/index.html, accessed: January 21, 2019.
6) S. Namba et al., Rev. Sci. Instrum. 87, 083503 (2016).
7) N. Ikoma et al., RIKEN Accel. Prog. Rep. 51, 144(2018).
8) W. A. J. Vijvers et al., Phys. Plasmas 15, 093507 (2008).
9) S. Huang et al., Phys. Plasmas 21, 123511 (2014).

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 52 (2019)

Maintenance of vacuum conditions of RILAC
S. Watanabe,∗1 Y. Watanabe,∗1 E. Ikezawa,∗1 K. Yamada,∗1 N. Sakamoto,∗1 M. Kase,∗1 O. Kamigaito,∗1
M. Nishida,∗2 K. Yadomi,∗2 J. Shibata,∗2 K. Oyamada,∗2 A. Yusa,∗2 N. Tsukiori,∗2 K. Kobayashi,∗2
S. Fukuzawa,∗2 T. Nakamura,∗2 R. Koyama,∗2 S. Ishikawa,∗2 M. Hamanaka,∗2 M. Nishimura,∗2 T. Ohki,∗2
H. Yamamoto,∗2 M. Tamura,∗2 and K. Kaneko∗2
Maintenances of vacuum condition in RILAC are described. There had been two big problems of vacuum
conditions at RILAC. One was a vacuum leak at a cavity No. 5, the other was a leak of vacuum at a cavity
A1. The cavity No. 5 had a vacuum leak, the pressureof its vacuum was higher than 1 × 10−4 Pa. As for a
problem of cavity No. 5, it was diﬃcult to handle it because of its heavy weight, large scale and complicatedstructure. As shown in Fig. 1, the cavity No. 5 hasa large vacuum chamber of which the inner wall wasused as an electrode called “outer conductor.” Insideof the outer conductor, there were several electrodes
to accelerate an ion beam. Some of the accelerationelectrodes were connected to a large cavity called “center conductor.” Junction area between the electrodeand the center conductor was sealed using an O-ring.
The opposite side of the wall of the center conductor
opposite side of the wall was exposed to atmosphere.
Flanges were sealed using O-rings. All O-rings of thevacuum-sealing ﬂanges on the outer conductor were
exchanged with new ones, however the pressure was
not improved, higher than 1 × 10−4 Pa. We found another air-leak point by using a helium leak detector
when we shot helium gas from an atmosphere side of
the center conductor. The cavity No. 5 was repaired infrom September to November. Another vacuum leakpoint was sealed face between electrodes and the cavity. When helium gas was shot from the atmosphereside of the center conductor to sealed area. A helium
leak detector was reacted. To access the O-ring on thecenter conductor, a large ﬂange of the outer conductor
was opened using a crane. To ﬁx the leak, the elec-

Outer Conductor
Beam

C

Center Conductor

Drift Tube
Shorting Device

Fig. 1. Schematic diagram of cavity No. 5.
∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

- 119 -

Fig. 2. Sealing face with a degenerate O-ring on center conductor of cavity No. 5.

trode was removed from the center conductor. A deteriorating O-ring across the ages was found as shownin Fig. 2 and the O-ring was replaced with new one.
When the electrodes were assembled, thin silver plates
were stacked on the joint area to place the electrodeson the level. The leak of the tank was ﬁxed and thepressure of the tank was improved to 9 × 10−6 Pa.
The cavity, A1, had vacuum leak on the bottom
ﬂange, however, a location of the leak point was not
identiﬁed precisely. We presumed that the air-leakpoint was under the paint covering the vacuum-sealing
ﬂanges because of the delayed response of the helium
detection. Thus, in October, after removing the paint,
we hunted the air-leak once more. The surface of theﬂange was masked by plastic tape except the checking area to block the ingress of helium gas. The tape
was re-covered every time the checking area changing.
At last, we found the air-leak point on an area of thecooling pipe on the ﬂange. The vacuum leak area wasfound and was applied by sealing agent (VACSEAL).
The pressure of A1 was improved to 3 × 10−6 Pa.

9. Instrumentation

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Application of the Generic Electronics for Time Projection Chamber(GET) readout system for heavy radioactive isotope collisionexperiments†
T. Isobe,∗1 G. Jhang,1∗,∗3 H. Baba,∗1 J. Barney,∗1,∗3 P. Baron,∗7 G. Cerizza,∗1,∗3 J. Estee,∗1,∗3 M. Kaneko,∗1,∗2
M. Kurata-Nishimura,∗1 J. W. Lee,∗1,∗4 W. G. Lynch,∗3 T. Murakami,∗1,∗2 N. Nakatsuka,∗2 E. C. Pollacco,∗7
W. Powell,∗5 H. Sakurai,∗1 C. Santamaria,∗1,∗3 D. Suzuki,∗1 S. Tangwancharoen,∗3 and M. B. Tsang∗3

†
∗1
∗2
∗3
∗4
∗5
∗7

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. A 899, 43–48 (2018)
RIKEN Nishina Center
Department of Physics, Kyoto University
National Superconducting Cyclotron Laboratory, Michigan
State University
Department of Physics, Korea University
Department of Physics, University of Liverpool
CEA Saclay IRFU/SPhNd3t

reco. with slope

4

He

10

reco. with height

3

He

102

6

Li

7

Li

10
1
0

100

200

300

400

500

600

700

800

dE/dX (A.U.)

Fig. 1. Energy loss distribution of each particle passing
through TPC. Trajectories of 1.6 ≤ p/Q ≤ 1.7 GeV/c
are selected. The spectrum of energy loss reconstructedwith the signal height is shown as a dotted line while
the spectrum of energy loss reconstructed with the signal
slope is shown as a solid line.

Max. ADC / slope

The SπRIT time projection chamber (TPC) is oneof the main devices for the SπRIT project at RIKENRIBF.1) The SπRIT project aims to study the densitydependent term of the symmetry energy using heavy RI
collision through the measurement of charged pions andlight nuclei. We have implemented the Generic Electronics for Time Projection Chamber (GET) in SπRIT-TPC
readout system. The operation of the GET electronics
during the last experiment in 2016 went well at DAQ arate of 60 Hz.
It was hard to identify Li isotopes clearly due to thelimitation of the ADC dynamic range. We have developed a method to measure energy loss by using theslope value of each signal instead of the pulse height.
Here, the slope is the gradient of the leading signal
shape. A cocktail beam of proton, deuteron, triton, 3 He,
4He, 6 Li, and 7 Li particles with a beam momentum ofp/Q ∼1.6 GeV/c is made with the BigRIPS fragment
separator. Figure 1 shows the energy loss distributionof each projectile. In the case of the high-gain configuration used for the pion measurement, the depositedenergy from the Z ≥ 3 particles is too high to identify
Li isotopes by using signal height information. Due tothe saturation of several pads along the Li trajectory,
the energy loss resolution of the Li trajectory is worse
than that of other light particle trajectories. By using
the slope value instead of signal height, it is possible
to increase the dynamic range of signal measurement sothat the distribution of 6 Li and 7 Li can be separated by
4 σ.
Figure 2 shows the calibration curves obtained by injecting a long rectangular pulse to the ground wire of
TPC: the maximum slope and ADC value as a functionof input charge. Although the maximum ADC value issaturated around an input charge of 120 fC, the maximum slope value still shows linearity beyond 120 fC.
According to the SPICE simulation, the linearity of theslope value extends up to 200 fC charge input, i.e. thedynamic range is increased by 65%.
This work is supported by the Japanese MEXT
KAKENHI Grant No. 24105004, the U.S. DOE un-

4000
3500
3000
2500

C

AD

2000
1500

slope

1000
500
0

0

20

40

60

80

100

120

140

Injected Charge (fC)

Fig. 2. Pad response induced by a long rectangular pulse
injected to the ground plane wire. The induced ADC
response is saturated for an injected charge above 120 fC.

der Grant Nos. DE-SC0004835, DE-SC0014530, 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 for analyzing data were provided by the
HOKUSAI system at RIKEN.
References

1) S. Rebecca et al., Nucl. Instrum. Methods Phys. Res. A
784, 513 (2015).
2) E. Pollacco et al., Phys. Procedia 37, 1799 (2012).
3) T. Isobe et al., RIKEN Accel. Prog. Rep. 48, 204 (2015).

- 121 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

PANDORA, a large volume low-energy neutron detector with real-timeneutron-gamma discrimination†
L. Stuhl,∗1,∗2 M. Sasano,∗2 K. Yako,∗1 J. Yasuda,∗3 H. Baba,∗2 S. Ota,∗1 and T. Uesaka∗2
Recent nuclear physics studies are increasingly focused on the region far from the valley of stability.
The increase in the intensity of available exotic isotopes enables the investigation of phenomena with low
cross-sections, such as inelastic scattering and chargeexchange (CE) reactions. Because the cross-sections of
the CE reactions are very low, it is crucial to eﬃciently
tag these reaction channels and minimize the contaminant events from other reaction channels with larger
cross-sections (e.g., elastic scattering, knockout reactions). The (p, n) CE reactions at intermediate energies(150–300 MeV/nucleon) are a powerful tool to study the
spin-isospin excitations in nuclei. The inverse kinematics1,2) enables the (p, n) reactions on exotic nuclei with ahigh luminosity. In this technique, neutron detectors areused to measure the time-of-ﬂight (ToF) of low-energy
recoil neutrons from a few hundred keV to a few MeV
produced from the (p, n) reaction. This methodology
has been successfully applied to study the Gamow-Teller
strength distribution from 56 Ni2) and 132 Sn3) isotopes.
We also started a program at RIBF aiming to study the
spin-isospin responses of 11 Li and 14 Be light drip line
nuclei.
The ﬁrst generation of neutron detectors designed
for these measurements, such as LENDA,4) WINDS,5)and ELENS6) cannot distinguish between neutrons andgamma rays. The random gamma background, whichmainly arises from the environment, cannot be removed
from the neutron spectra. We developed the PANDORA(Particle Analyzer Neutron Detector Of Real-time Acquisition) system as an upgrade of the WINDS detector.
PANDORA is based on a plastic scintillator, sensitive
to the diﬀerences between neutrons and gamma rays.
Neutrons and gamma rays can be distinguished by theirpulse shapes because their signals in the tail region diﬀer(larger tail for neutrons). PANDORA employs a digital
data acquisition system. The signals are read-out withCAEN V1730 digitizer.
We presented the ﬁrst results on the pulse shape discrimination capabilities of the new large volume plastic
scintillator EJ-299-34-based device PANDORA coupled
to a digital data acquisition system. The PSD performance was compared to that of the well-established EJ299-33 scintillator.7) We introduced the PSDmean oﬄine
value as the arithmetic mean of online PSD values of
two single-end read-outs (PSDleft and PSDright ). The
ToF distributions acquired using a 252 Cf ﬁssion source
†
∗1
∗2
∗3

Condensed from the article in Nuclear Instruments and Methods in Phys. Res. A 866, 164 (2017)
Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center
Department of Physics, Kyushu University

Fig. 1. PSDmean vs. ToF spectrum shows a good separation of neutron and gamma-like events. The sharp peak
below 10 ns corresponds to events identified as gamma
rays, while the distribution in the higher ToF region and
PSDmean > 0.15 represents neutron-like events. The inner scale corresponds to the kinetic energy of the detected
neutrons obtained using the ToF method. A large random gamma background can also be observed.

show that with PANDORA, 91±1% of all detected neutrons can be identiﬁed online and 91±1% of the detectedgamma rays can be excluded. This online gamma rejection (individual threshold conditions on the left andright PSDs) reduces the background by one order ofmagnitude.
Our goal of particle-based real-time triggering was
successfully attained. This development allows (p, n) reactions on exotic nuclei to be measured with a secondary
beam intensity up to 106 particle/sec. Furthermore,this new setup provides opportunity for reaction studies that involve emission of low-energy neutrons. The
PANDORA system is capable to provide a ﬁltered data
package of energy, timing, PSD information, and digitized pulse shape, which can be used for further improvements oﬄine.
References
1) G. Perdikakis et al., IEEE Trans. Nucl. Sci. 56, 3 (2009).
2) M. Sasano et al., Phys. Rev. Lett. 107, 202501 (2011).
3) M. Sasano et al., EPJ Web of Conf. 107, 06003 (2016).
4) G. Perdikakis et al., Nucl. Instrum. Methods Phys. Res.
A 686, 117 (2012).
5) K. Yako et al., RIKEN Accel. Prog. Rep. 45, V, (2012).
6) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A 736,
1 (2014).
7) P. Blanc et al., Nucl. Instrum. Methods Phys. Res. A 750,
1 (2014).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Measurement of total kinetic energy using LaBr3 (Ce) crystal in
ZeroDegree spectrometer for two-step experiment
H. Suzuki,∗1 D. S. Ahn,∗1 N. Fukuda,∗1 H. Takeda,∗1 Y. Shimizu,∗1 R. Taniuchi,∗1 H. Wang,∗1 S. Takeuchi,∗2,∗1
and K. Yoshida∗1

Light output [ch]

8400
8300
8200
8100
8000
7900
7800
7700
7600
7500

12.6 12.8 13 13.2 13.4 13.6 13.8 14

Fig. 1. Relation between light output from LaBr3 (Ce) crystal
2
and calculated EZ by ATIMA.5)∗2

RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo

129

47+

Ag

102

10

126

Ag46+

2.7

A/Q

2.75

1
2.8

2.85

Fig. 2. Separation of Ag isotopes in A versus A/Q. 4.6σ
separation was achieved between 129 Ag47+ and 126 Ag46+ .

the light output and calculated energy-loss of RIs using
an energy-loss code ATIMA.5) Owing to the quenchingeﬀect, the light output was not proportional to the en2
ergy loss. In this experiment, EZ (E; energy loss in the
crystal) was found to be proportional to the light output,
as shown in Fig. 1. In previous studies by Kobayashi4)
2√E respectively, were proand Taniuchi et al.,6) EZ 2 andZ
posed as the proportional variables. It is unclear why
the quenching eﬀects are diﬀerent in these three cases.
It may be caused by the width of the Z range, which was
41–50 in our case, 28–52 in Ref. 4), and 8–50 in Ref. 6).
The distribution of A in the two-step experiment was
0.95 in RMS around 129 Ag47+ . Thus, the resolution of
A was 0.8% and 3σ separation was achieved between the
fully-stripped 129 Ag47+ and H-like 126 Ag46+ in mass. In
A/Q axis, 3.5σ separation was obtained between these
two isotopes. Thus, 4.6σ separation was achieved using
both A/Q and A separations. Figure 2 shows the separation of Ag isotopes in the two-step experiment in A
versus A/Q plot. The fully-stripped RIs are well separated from the H-like RIs. The charge number, Q, wasdeduced from A/Q and A. 2.5σ separation was achievedin the Q separation.
References

E 2/Z [GeV2] (calc. by ATIMA)

∗1

134
132
130
128
126
fully−
124 stripped ions122
H−like ions
120
118
116
2.55 2.6
2.65

Mass number (A )A LaBr3 (Ce) crystal was used as the total-kineticenergy (TKE) counter for particle identiﬁcation (PID)
in the ZeroDegree spectrometer in the two-step experiment.1) In this experiment, events of partially-strippedradioactive isotopes (RI) were not negligible, because themass numbers, A, of RIs produced at the target at theentrance of ZeroDegree were over 100 and their kinetic
energies were 200 MeV/nucleon. For the PID, the atomic
number, Z, and the mass-to-charge ratio, A/Q, were deduced based on a TOF-Bρ-∆E method. However, theA/Q resolution in ZeroDegree with Medium-ResolutionAchromatic mode2) was 0.061% in RMS and inadequate
to separate fully-stripped RIs from the partially-stripped
ones. Thus, the value of A was deduced from the velocity(β) and TKE of each RI and was used for the separation.
The LaBr3 (Ce) crystal3,4) was mounted at the endof ZeroDegree. It is cylindrical in shape with 3-inch
diameter and length, covered with a 0.5-mm thick Al
housing. Nine PIN-photodiodes were attached to theback of the crystal through a light-guide made of Lucite.
Five diodes with eﬀective areas of 18 mm2 (S3204-08;
Hamamatsu Photonics K.K.) were arranged in the shapeof a cross and other four diodes of 10 mm2 (S3590-18;
Hamamatsu) were placed at the four corners. The signal
from each diode was ampliﬁed by a pre-ampliﬁer (MSI8; mesytec GmbH & Co. KG) whose dynamic range
was set to be 1 GeV in Si energy-loss equivalent anda shaping ampliﬁer (MSCF-16; mesytec) whose shaping
time was set to be 2 µs.
The energy of the crystal was calibrated by comparing

1) H. Suzuki et al., RIKEN Accel. Prog. Rep. 52, (2019).
2) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 03C003(2012).
3) R. Kambayashi, Master’s thesis, Rikkyo Univ. (2011).
4) K. Kobayashi, Master’s thesis, Rikkyo Univ. (2012).
5) ATIMA web page, https://web-docs.gsi.de/~weick/atima.
6) R. Taniuchi et al., RIKEN Accel. Prog. Rep. 48, 210(2015).

- 123 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Prototype of new delay line with chip inductors for the PPAC
H. Sato,∗1 H. Baba,∗1 and K. Yoshida∗1
In Parallel Plate Avalanche Counter (PPAC), which
is used at the BigRIPS, the XY position is deduced
by using the delay line readout method.1) The X andY electrode strips are connected to multi-tapped delaylines (DLs). The inductance of the DL is formed bya coil made by winding a ϕ0.3 wire wound around a
ϕ2.0 Bakelite rod. Additionally ϕ0.12 lead wires are
soldered onto the coil wire every eight turns. Thus, thefabrication and maintenance of this DL is a diﬃcult
work that requires an expert for soldering. To simplify
the DL fabrication, prototyping of new DL consistingof chip inductors and capacitors has been started.
The new DL is fabricated by the reﬂow soldering
method. A soldering paste is put on the pads of theG10 board via a 200 µm-thick mask. The chips areplaced on the pads and then the board is heated up toaround 160◦ C on a hot plate to melt the solder. Imagesof the ordinary DL and the new DL are shown in Fig. 1.
Several new DLs were fabricated and tested. In
this report, the properties of the X DL named
CLDLX#02 are described. The chip inductors are
Murata LQW2BAN91NG00L, whose inductance L is
91 nH ± 2%.
The chip capacitors are Murata
GRM2162C1H390JZ01D, whose capacitance C is 39 pF± 5%, and chips having the same C within one decimal
place were used √to realize the same delay time of one
pitch (Tdt = 1.07 LC). The measured average Tdt was
2.02 ns with 1.0% of the standard deviation.
The performance of the 240 mm × 150 mm PPAC
with new DLs was evaluated with an α source. Figure 2 (a) shows the X-axis position spectrum of the
α-rays that are uniformly irradiated on the PPAC. The
uniformity of the detection sensitivity from −108 mm

Fig. 2. X-axis position spectrum: (a) uniformly irradiated,(b) with a position calibration mask.
Table 1. Characteristics of CLDLX#02 and 25X#34.
inductance [nH]capacitance [pF]
total delay time [ns]delay time of one pitch [ns]signal speed [mm/ns]
attenuation rate [%]uniformity of sensitivity [%]position resolution [mm]

CLDLX#02
91
39.1
193
2.02
1.265
65
1.8
0.32

25X#34
90
38.4
192
2.02
1.261
68
1.4
0.25

to +108 mm (90% of the full range of X) excluding
the statistical ﬂuctuation was 1.8%. Figure 2 (b) is the
spectrum measured with a position calibration mask,
which has a slit interval and width of 5 and 0.5 mm, respectively. The position resolution was measured to be
0.32 mm in σ. The characteristics of CLDLX#02 aresummarized in Table 1 with those of an ordinary multitapped DL (25X#34) for comparison. As presented,
the position resolution of CLDLX#02 is slightly wider
than that of the 25X#34. Thus, with further modiﬁcation to obtain better performance, the new DL canbe used for the PPAC instead of the ordinary DL. In
addition, we are also considering another type of DL
whose coil is directly patterned on the G10 board.
Fig. 1. Images of the DL boards for X. (a) ordinary multitapped DL. (b) new DL.
∗1

RIKEN Nishina Center

Reference

1) H. Kumagai et al., Nucl. Instrum. Methods Phys. Res.
B 317, 717 (2013).

- 124 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Development of electronics to allow vertex determination in the KISS
MSPGC
P. Schury,∗1 Y. Hirayama,∗1 H. Choi,∗1,∗2 H. Miyatake,∗1 Y. X. Watanabe,∗1 and M. Mukai∗1,∗3∗3

KEK Wako Nuclear Science Center
Seoul National University
Institute of Physics, University of Tsukuba

200 MΩ

∗2

1 nF

∗1

HV

(a)

10 MΩ

CR-110-Sig/2+CcouplingCM50Ω

AD8138-+Sig/2

Proportional gas counter tube(b)+Sig/2+-Sig/2-

Sallen-Key

AD8130
RPZ

Ref
R1

Guassian
Pulse

CR-200FB

g = 1 + R2/R1
R2+Sig/2+-Sig/2-

AD8130Ref
FB

470 pF

Trigger
Pulse
49Ω

The goal for the KEK Isotope Separation System(KISS)1) is to provide precise nuclear data of neutronrich nuclei near N = 126. Such nuclei, which play an important role in the r-process, are diﬃcult to produce bytraditional means (e.g. in-ﬂight ﬁssion/fragmentation,fusion, ISOL) and therefore KISS uses multi-nucleon
transfer reactions to produce them. The rates of interesting nuclei are typically less than 1 s−1 .
For understanding the nature of the N = 126 bottleneck presumed to be responsible for the 3rd peak of
the r-process requires precise atomic masses and decay
half-lives. In order to provide the nuclear astrophysics
community with the necessary precise half-life data, amulti-segmented proportional gas counter (MSPGC)2)
was developed for KISS. The system as initially envisioned utilized two concentric rings of proportional gas
counter (PGC) tubes (16 in each ring), thereby allowing
the use of “hit pattern” analysis to discriminate background events such as e.g. cosmic rays. This proved to
be a successful strategy which allowed meaningfully precise half-life determination from species delivered with
rates down to 0.1 s−1 .
In order to push the half-life measurements to N =126, however, will require use of the MSPGC with rates
an order of magnitude lower. To accomplish this, the
PGC tubes have been upgraded to utilize a resistive
wire. By detecting the charge deposited on each end of
the wire, it is possible to extract the position of the decay detection along the length of the detector. The 3D
decay vertex made possible be this added information
should allow half-life determination from yields on theorder of 0.01 s−1 .
This requires a charge-sensitive pre-ampliﬁer, shaping ampliﬁer, and trigger generator for both ends ofeach PGC tube −64 sets in total. Noise considerations require the pre-ampliﬁer to be located as close
to the PGC as possible, while space constraints makeit infeasible to pack everything into the area near the
MSPGC. A small circuit board with power conditioners, a Cremat CR-110 charge-sensitive ampliﬁer (CSA)(g = 1.6 V/pC), and an AD8138 diﬀerential line driveris installed close to each end of every PGC tube. The
diﬀerential signals are immune to environmental noise.
An array of receivers, as well as power supplies,
is installed within a 3U 19” crate installed in a rack
≈ 3 m from the MSPGC. The power for the CSA circuit boards is supplied via a long ribbon cable. The differential line drivers following the CSA allow the signal
from each detector to be sent to the receiver crate via

Fig. 1. Sketch of circuitry installed (a) near to and (b) at
a distance from the MSPGC. The signal from the CSA
is converted to a diﬀerential signal to allow noise-freetransmission, via long ribbon cable, prior to applicationof a shaping ampliﬁer. In the inset the trigger pulse islight blue and the Gaussian pulse is purple. The ADC istriggered by the falling edge of the trigger pulse, 2.5 µs
prior to the peak of the Gaussian pulse.

the long ﬂat ribbon cable as well. The receiver boards
use a pair of AD8130 diﬀerential receiver ampliﬁers toprovide a decoupled pair of signals, one to be processedby a CR-200 shaping ampliﬁer and the the other to trigger the 14-bit Hoshin C008 analog-to-digital converter(ADC) used to measure the pulse-height of the CR-200
output and determine the detection position along the
PGC. Details are given in Fig. 1.
In the initial testing with Ccoupling = 1 nF, large∼100 kHz oscillations were observed in the CSA output. After consultation with Cremat, it was determinedthat the each CSA saw the coupling capacitor on the
opposite end of the PGC as a heavy load. Reducing
Ccoupling to 100 pF gave clean, stable signals. Development is ongoing.
References

1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 412, 11 (2017).
2) M. Mukai et al., Nucl. Instrum. Methods Phys. Res. A
884, 1 (2018).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Development of Plastic Scintillator Barrel for WASA at GSI
R. Sekiya,∗1 V. Drozd,∗2 H. Fujioka,∗3 K. Itahashi,∗4 S. Y. Matsumoto,∗1,∗4 T. R. Saito,∗2,∗5,∗6 K. Suzuki,∗7 and
Y. K. Tanaka∗2,∗8

Fig. 1. Schematic configuration of a single slat of PSB.
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

Department of Physics, Kyoto University
GSI Helmholtz Center for Heavy Ion Research
Department of Physics, Tokyo Institute of Technology
RIKEN Nishina Center
High Energy Nuclear Physics Laboratory, Cluster for Pioneering Research, RIKEN
Helmholtz Institute Mainz
SMI
II. Physikalisches Institut, Giessen University- 126 -

100

Time Resolution σt [ps]We plan to conduct new experiments for hypernuclear spectroscopy1) and η ′ -mesic nuclei exploration2)
using the WASA central detector3,4) and the fragment
separator (FRS) at GSI. The WASA central detector
consists of a superconducting solenoid magnet, a plastic scintillator barrel (PSB), and a cylindrical drift
chamber for charged particle measurement and CsI
calorimeters for gamma-ray measurement.
We are upgrading the cylindrical part of PSB toachieve 100 ps in time resolution based on the experimental requirement. In the old conﬁguration, we had
only one photomultiplier tube with a light guide foreach scintillator slat of PSB. We improved the time resolution by detecting photons on both sides using multipixel-photon counters (MPPCs). Since the PSB will
be located inside the superconducting solenoid magnet, we chose detectors that can be operated under amagnetic ﬁeld. MPPC satisﬁes this requirement.
We made a single slat of PSB as schematicallyshown in Fig. 1. The size of the plastic scintillator
is 550 × 38 × 8 mm3 . We adopted Eljen EJ-230, which
has an attenuation length of 120 cm. We attachedfour MPPCs (Hamamatsu Photonics S13360-6050CS)
on each side of the plastic scintillator and electricallyconnected them in series. The eﬀective area of the
MPPC is 6 × 6 mm2 . The MPPCs were then connected to ampliﬁers developed in Ref. 5). The ampliﬁed signals were recorded by a waveform digitizer(CAEN V1742) with a sampling frequency of 2.5 GHz.
In order to evaluate the time resolution, we irradiated the plastic scintillator with electrons from a 90 Srsource with an endpoint energy of 2.28 MeV. A slit witha gap of 2 mm was inserted between the plastic scintil-

95

90

85

80
Overvoltage
4V

75

6V
8V

70
−30

−20

−10

0

10

20
30
Source Position [cm]Fig. 2. The dependence of the time resolution σt on source
positions and applied bias voltages.

lator and the 90 Sr source. We performed mesurements
by changing the position of the source to investigate
the hit position dependence. The overvoltage was alsochanged to 4, 6, and 8 V.
We evaluated the time resolution of the plastic scintillator by analyzing the waveform data. In the analysis, we simulated a function of constant fraction discriminators by using a software to obtain the precision
arrival time of signals at the right and left ends of theplastic scintillator (T R and T L ). The time resolutionof this single slat of PSB (σt ) can be estimated byﬁtting a (T R − T L )/2 histogram with a Gaussian function and taking its standard deviation, neglecting thehit position distribution of the electrons.
Figure 2 shows the time resolution σt as a functionof the source positions. Diﬀerent colors correspond to
diﬀerent bias voltages. We achieved a time resolution
better than 100 ps for all the tested conditions. We
also found that the time resolutions become better as
the overvoltage is decreased.
Based on the measurements described above, we
conﬁrmed that a single slat of PSB achieves the required time resoution. We are planning a more systematic evaluation of the PSB performance by using
mono-energetic proton beams.
References

1) T. R. Saito et al., proposal GSI-SIS S447 (2017).
2) K. Itahashi et al., proposal GSI-SIS S457 (2017).
3) C. Bargholtz et al., Nucl. Instrum. Methods Phys. Res.
A 594, 339 (2008).
4) H.-H. Adam et al. (WASA-at-COSY Collaboration),
arXiv:nucl-ex/0411038 (2004).
5) P. W. Cattaneo et al., IEEE Trans. Nucl. Sci. 61, 2657 (2014).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Energy dependence study of cylindrical drift chamber used 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. Shibaguchi,∗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. Murata∗4
The purpose of the MTV (Mott polarimetry for Tviolation) experiment is to ﬁnd a large time reversal
symmetry violation (T-violation) in polarized 8 Li β − decay. T-violation may arise in triple vector correlation(R-correlation) in beta decay. R-correlation causes electron transverse polarization and it can be measured bydetecting electron Mott scattering asymmetry. In the
MTV experiment, which has been running at TRIUMFISAC (Isotope Separator and Accelerator), cylindricaldrift chamber (CDC) is used as a tracking detector tomeasure angles of the electron emission and backward
scattering per event.1) The physics data were collected
in 2017.
In 2018, we studied β − ray energy dependence of CDC
to predict Mott asymmetry measured in our system.
The electron emission distribution of β − decay, ω, is expressed as:2)
[
]
⃗
⟨J⟩
p⃗e
×
ωdEe dΩe ∝ 1 + R⃗σ ·+ ....
(1)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 energy of electron, respectively. Coeﬃcient R is predicted from the ﬁnal state interaction (FSI) between theelectron and daughter nucleus. In the standard model,
coeﬃcient R of FSI in 8 Li β − decay is predicted as
RFSI (8 Li) =

αZme
.
3pe

(2)

Where α is the ﬁne structure constant, Z is the atomic
number of daughter nucleus, and me is the electron mass.
RFSI is a non-zero value but it doesn’t violate time reversal symmetry. If a signiﬁcant diﬀerence exists between
theoretical RFSI and measured R, it may imply the existence of T-violation. These formulae show that β −Fig. 2. Energy spectra using 90 Sr radiation source at five different positions from the PMT.

emission distribution depends on β − ray energy. In our
experiment in 2017, we measured β − emission distribution (Eq. (1)) in its integrated form with Ee . The prediction of expected asymmetry in our detector system
requires the determination of the minimum detectableelectron energy. In the 2018 experiment, we measured
energy spectra detected by CDC using 90 Sr radiation
source and its energy threshold was deduced.
The measurement setup consists of stopping scintillation counters (SCs: used as trigger scintillator of CDC)
and two PMT attached on both sides of SC. The mostsigniﬁcant ambiguity of CDC energy threshold is due toSC whose length is 675 mm. When an electron hits adiﬀerent point of SC, the amount of photons reaching
PMTs also vary. We placed the radiation source on the
SC with a collimator at ﬁve diﬀerent positions to measure the ambiguity of energy threshold (Fig. 1). Figure 2
shows the energy spectra using 90 Sr radiation source at
ﬁve diﬀerent positions from the PMT. The end point energy and threshold are deﬁned by ﬁtting on these datawith the intrinsic response function of 90 Y β − ray. The
cutoﬀ channels of the spectra correspond to the threshold. From these analyses, we determined the averageenergy threshold as
Eth = (6.5 ± 2.2) × 10−1 MeV.

Fig. 1. Setup of the measurement to study the source position
dependence.
∗1
∗2
∗3
∗4
∗5

Department of Physics, Nagoya University
RIKEN Nishina Center
TRIUMF
Department of Physics, Rikkyo University
Cyclotron and Radioisotope Center, Tohoku University(3)

The energy threshold that was obtained in 2018 is necessary to calculate the asymmetry expected in our detector. In contrast, we need more analyses on the physics
data to set ﬁnal results R. In addition, the development of track detection method by machine learning isin progress to reduce systematic errors.
References

1) J. Murata et al., Hyperfine Interact. 237, 125 (2016).
2) J. D. Jackson, S. B. Treiman, H. W. Wyld Jr., Phys. Rev.
106, 517 (1957).

- 127 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Development of long and high-density data bus for sPHENIX INTT
detector
T. Hachiya,∗1,∗2 Y. Akiba,∗1 H. Aso,∗1,∗3 D. Cacace,∗4 E. Desmond,∗4 T. Ichino,∗1,∗3 M. Isshiki,∗2 T. Kondo,∗5
H. Kureha,∗2 E. Mannel,∗4 G. Mitsuka,∗1 I. Nakagawa,∗1 R. Nouicer,∗4 R. Pisani,∗4 K. Sugino,∗2 A. Suzuki,∗2
M. Tsuruta,∗1 T. Todoroki,∗1 and Y. Yamaguchi∗1
The intermediate tracker (INTT) is a silicon strip barrel detector for the sPHENIX experiment.1) INTT is
implemented in a tight space between an inner silicondetector (MVTX) and the outer TPC, and the readout
electronics are placed 120 cm away from the detector.
The data bus of INTT must satisfy the following requirements:2) (1) ﬂexibility, (2) length of at least 120 cm, (3)high-density signal line (128 lines/5 cm), and (4) highspeed signal transfer (by LVDS). It is challenging to meet
all the requirements because high-speed signal transfer
and a long data bus are contradictory.
To investigate the technical feasibility of the data bus,
we made a prototype of the long and high-density data
bus using ﬂexible printed circuit (FPC), which is a ﬁlm
based PC board. A liquid crystal polymer (LCP) waschosen as the ﬁlm material to reduce signal loss due tothe small dielectric tangent. The prototype is a threelayer structure in which the middle signal layer is sandwiched by the top and bottom ground layers for a differential impedance (Zdiﬀ ) of 100 Ω. Figure 1 shows an
FPC sheet containing ﬁve sets of the signal layer before
laminating the top and bottom layers.
We evaluated the electrical and mechanical characteristics of the prototype. As a result, we found thatthe signal attenuation and return loss are −3 dB and−20 dB, respectively, and Zdiﬀ is 90 Ω. The thiner line ispreferable for 100 Ω, but more diﬃcult to produce without troubles. The signal distortion was visually tested
using the eye diagram. The eye is clearly open as shownin Fig. 2 (left). We also found that the accuracy of thewidth of the signal lines is ±3 µm from the measurementof the line widths for 40 lines on the FPC as shown in
Fig. 2 (right). These results show that the prototype
meets the requirements within the scope of the speciﬁcation.
However, two issues are found in the prototype FPC.
One is that the peel strength of the laminated layers is
weak, and the other is that it is diﬃcult to produce thethrough holes for long FPC. We studied several ways
120cm

Fig. 1. LCP sheet of the signal layer for the prototype.
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Department of Physics, Nara Women’s University
Department of Physics, Rikkyo University
Brookhaven National Laboratory
Tokyo Metropolitan Industrial Technology Research InstituteFig. 2. Characteristics of the prototype FPC. (Left) Clear
opening of eye diagram (Right) small variation of the line
widths.

Cu plang ~35μm
Cu
Cu
LCP

Cu
Cu
LCP

Adhesive

Adhesive

LCP

LCP

Adhesive

Adhesive

Cu

Cu

LCP
Cu

Cu

Cu

LCP
Cu

Fig. 3. Result of the Cu-plating for the four layer FPC. (Left)
Schematic view of the laminated structure of FPC with
Cu-plating. (Right) Result of Cu-plating.

to improve the peel strength. The current status is reported in Ref. 3).
The through hole is produced by drilling a hole on
the FPC and Cu-plating the surface of the hole throughan electro-chemical process. This requires a big chemical bath to soak the entire FPC. We looked for a company that has a bath big enough for INTT data bus.
Along with the company, we tested the Cu-plating on
the through hole for the 4 layer FPC. Figure 3 shows theCu-plating result, which was successful. We will investigate the reliability of the through hole with a thermal
shock test as a next step.
We evaluated the feasibility of the long and highdensity data bus using FPC. Most of the issues weresolved, and some technical issues found in the study are
under further investigation. Based on the knowledge
from the prototype, we are making the production version of the data bus for INTT. The production version
will be tested in 2019.
References

1) I. Nakagawa et al., in this article.
2) T. Hachiya et al., RIKEN Accel. Prog. Rep. 51, 162(2017).
3) M. Tsuruta et al., in this article.

- 128 -

2

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Performance evaluation of sensor module for INTT at sPHENIX
A. Suzuki,∗1,∗2 Y. Akiba,∗1 H. Aso,∗1,∗3 D. Cacace,∗4 E. Desmond,∗4 T. Hachiya,∗1,∗2 T. Ichino,∗1,∗3 M. Isshiki,∗2
T. Kondo,∗5 H. Kureha,∗2 E. Mannel,∗4 G. Mitsuka,∗1 I. Nakagawa,∗1 R. Nouicer,∗4 R. Pisani,∗4 K. Sugino,∗2
M. Tsuruta,∗1 T. Todoroki,∗1 and Y. Yamaguchi∗1
Intermediate silicon strip tracker (INTT) is one of the
tracking detectors of sPHENIX.1) As shown in Fig. 1,
INTT ladder consists of high-density interconnect (HDI)FVTX chips for PHENIX (FPHX) and silicon strip sensor.2) HDI is a ﬂexible PC board to provide input andoutput for FPHX. The power to FPHX and silicon strip
sensor are supplied through HDI. FPHX is a readout
LSI chip used for PHENIX. 26 FPHX are implemented
into the INTT ladder. One FPHX readouts 128 strip
channels. Each channel is equipped with a shaping ampliﬁer and 3-bit ADC. There are two diﬀerent sizes ofthe silicon strip sensor. One of them is 78 × 16 mm forA (20 mm for B). It is sensitive in ϕ direction.
We built a test bench to evaluate the sensor module
performance at Nara Women’s University as shown in
Fig. 2. The read-out system of the bench is described
below. First, the hit data is sent from FPHX to read-out
card (ROC) through a ﬂexible cable, and are read-out at
ROC. Data are sent from ROC to the front-end module(FEM) through an optical ﬁber and to be formatted.
Finally the data from the FEM in the PC is recorded.
Figure 3 shows the schematic drawing of the read-out
system.
To check the functionality of the read-out system, we
input a test pulse from ROC to FPHX with changing

Fig. 2. Test bench setup.

∗2
∗3
∗4
∗5

Fig. 4. (a) ADC vs pulse height (b) Pulse height vs strip
channel.

pulse height and measure ADC. Figure 4 (a) shows thecorrelation between input pulse height and output ADC
in a chip. Every chip responded linearly as expected.
There were some strange signals in ADC 7 of a chip.
Figure 4 (b) shows the number of hits (z-axis) as a function of pulse height (y-axis) in diﬀerent strip channels(x-axis). All channels responded correctly and the hit
eﬃciency improved at the threshold (pulse heights arenear 30). The read-out system operated properly.
We measured the cosmic ray with an external trigger to study the response of minimum ionizing particle(MIP). As shown in Fig. 3, the sensor module and external trigger overlap each other, and the coincidence ofboth sensor module and external trigger decreases thenoise. We are in the progress of accumulating data.
In the next step we will qualitatively evaluate thenoise and eﬃciency by measuring the radiation source
and cosmic ray. We plan to conduct the beam test at
Fermi lab. in 2019 to evaluate the sensor modules.

Fig. 1. INTT ladder.

∗1

Fig. 3. The schematic drawing of the readout system.

RIKEN Nishina Center
High Energy Physics Department, Nara Women’s University
Department of Physics, Rikkyo University
Brookhaven National Laboratory
Management and Planning Department, Tokyo Metropolitan
Industrial Technology Research Institute

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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RIKEN Accel. Prog. Rep. 52 (2019)

Slit system between the foci F2 and F3 of the BigRIPS separator
K. Yoshida,∗1 M. Ohtake,∗1 and Y. Yanagisawa∗1
A new slit system has been installed between thesecond and third foci (F2, F3) of the BigRIPS separator, as shown in Fig. 1. The slit system is used to
select the angles of RI beams produced at the target(F0) because it is placed at the point-to-parallel spot
where the beam angles focusing at F2 are converted topositions by beam-line magnets.
The inset of Fig. 1 shows the structure of the slit
system. It consists of horizontal and vertical slits andhas a similar structure as the F2 or F7 slit system.1)
It was installed in a vacuum chamber whose inner dimensions were 750 × 360 × 875 mm3 . Slit-blades weremade by tungsten alloys (HAC2, Nippon Tungsten Co.
Ltd.) with dimensions 150 × 150 × 80 mm3 (horizontal) and 240 × 120 × 80 mm3 (vertical) and weights
38 and 44 kg, respectively. They were connected to
the linear actuators mounted on the wall of the vacuum chamber through the vacuum feedthroughs. The

slit-blade positions were remotely controlled using the
stepping motors of the linear actuators. A position
accuracy of ± 0.1 mm was achieved. To support theheavy slit-blades, a rail and cam followers were used forthe horizontal slits, whereas Conston springs were used
for the vertical slits. A detector stage for the position
sensitive detector was also installed at the upstream ofthe slits in the vacuum chamber.
The hardware of the slit system was installed in
March 2018 and its control software was modified in
April 2018. The slit system became operational at the
beginning of May 2018. Since then, the slit system isused as the standard device to select RI beam angles
in the BigRIPS separator.
Reference
1) K. Yoshida et al., RIKEN Accel. Prog. Rep. 38, 293(2005).

Fig. 1. Layout of the BigRIPS separator. The target (F0) and seven foci (F1-F7) of BigRIPS are indicatedin the figure. Inset is the enlarged drawing of the newly installed slit system.

∗1

RIKEN Nishina Center- 130 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Fast beam interlock system for BigRIPS separator
K. Yoshida∗1
The fast beam interlock system for the BigRIPS
separator1) was designed and constructed in 2014 andhas been in operation since then to protect the beamline equipment from hitting the misaligned intensive
primary beams due to magnet failure. The interlock
system utilizes four compact RIO systems (cRIO) of
National Instrument Co. Ltd. as the processing modules and continuously monitors the power supplies of
34 magnets placed at the primary beam line and BigRIPS, where a primary beam is transported. The
current monitor signals from the power supplies are
digitized by ADCs in cRIO every 2 µs and comparedwith the pre-deﬁned upper and lower limits. A fault
signal is generated if the digitized values are beyond
these limits. The fault signals are merged into otherfault signals and fed to the beam chopper system tocut oﬀ the beam. The total response time, which isdeﬁned as the time between an analog signal drift anda beam stopping at the third focus (F3) of BigRIPS,
was ∼200 µs for a 48 Ca 345 MeV/nucleon beam.
During the operation of fast interlock system, theoriginal system was found to be weak for the ﬂuctuation of input noises. The noise of current monitor
signals is not always stable. If the noise suddenly increases, the interlock system detects it as the drift ofthe current output and generates the fault signal. The
beam is then stopped by the beam chopper. This happens a few times per day during the beam time.
The inspection of the current monitor signal using a
digital storage type oscilloscope revealed the existenceof two types of noise: a bi-polar ringing-like noise withhigh frequency (more than 2 MHz), a short unipolar
pulse whose duration is approximately 20 µs. The latter was created with the discharge of electrostatic deﬂector EDC of the SRC. To prevent the detection ofthese noises, noise ﬁlters are inserted in the analog input lines.
One such noise ﬁlter is a passive low-pass ﬁlter. EMI
ﬁltering capacitor EMIFIL DDS1 0.022 µF of Murata
was installed at the current monitor outputs of magnet
power supplies. The moving average method was also
implemented after the ADC of cRIO system, considering the average of 2 to 16 successive digital values fromthe ADC. Because ADC provides the converted value
every 2 µs, the averaging takes place between 4 and32 µs. By installing the EMI ﬁlter and taking the average of 16 successive AD values, the ringing like noise
was completely eliminated from the system. However,the short pulse noise could still be detected because
the pulse was slower than the EMI ﬁlter and unipolar
pulses were not eliminated by averaging.
∗1

RIKEN Nishina Center- 131 -

Fig. 1. Logic diagram of upgraded fast interlock system.

To eliminate the short pulse noise, a time-over-limit
detection mechanism was further added to the interlock logic. This was accomplished by installing a bitshift register on the output of the comparator, which
compared the digitized signal and pre-deﬁned limits.
Each output of the comparator was stored in the ﬁrst
bit of the bit-shift register. The remaining bits of theregister were pre-shifted by one bit before storing theﬁrst bit. Thus, the 16 bit register stored 16 successive comparison results. A failure signal was generated
when all 16 bits were in the “on” state. With this algorithm, the failure signals were only generated for the
input signals whose amplitudes exceeded the limit by
32 µs. Therefore, the deviation of input signals shorter
than 32 µs was completely ignored.
The interlock logic was modiﬁed as shown in Fig. 1
by modifying the FPGA program code in the cRIO system and no hardware modiﬁcation was required. The
actual modiﬁcation was performed in April 2018 andsince then, the fast beam interlock system has been
operated with no noise.
Reference
1) K. Yoshida et al., RIKEN Accel. Prog. Rep. 47, 169(2014).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Thermal model simulation of high-power rotating target for BigRIPS
separator
Z. Korkulu,∗1 K. Yoshida,∗1 Y. Yanagisawa,∗1 and T. Kubo∗1,∗2
Since 2007, a water-cooled high-power rotating disktarget made of beryllium or tungsten has been used as
the production target at the in-ﬂight radioactive-isotope(RI) beam separator BigRIPS.1,2) The diameter of therotational disk is 30 cm while the thickness can be optimized according to the atomic number and the energyof the selected projectile. To obtain a variety in thickness, the circumference edge of each disk has two steps
to realize less thicknesses. The rotational disk target
system was designed to withstand the maximum beam
intensity of 238 U at 345 MeV/nucleon and 1 particle µA.
Although only about 20% of the goal beam intensity of
82 kW has been achieved, the high-power rotating target system has been successfully operated with various
beams. Because the present primary beam intensity ismuch lower than the goal value, the requirement that Be
could withstand the goal intensity cannot be experimentally commissioned. Therefore, we started to develop
simulations based on ANSYS Parametric Design Language (APDL)3) to calculate the beam spot temperature
at various conditions. Earlier, a prototype target system
was designed and constructed using the same simulation
code.4,5)
In the analysis, a complete model built by APDL wasused. The primary beam was focused at a diameter of
1 mm (FWHM) with Gaussian beam distribution. The
power deposition in beryllium material was calculatedwith the LISE++ simulation code.6) To include the effect of radiation cooling, the emissivity of 0.57 was used
for the surface of the Be disk.5) The target disk wastightly ﬁxed with screws on the water-cooled aluminum
plate (see Fig. 1) and the boundary temperature for the

Fig. 2. A 48 Ca primary beam at 345 MeV/nucleon with
470 pnA (7.8 kW in beam power) onto the beryllium target of 10 mm thickness. The heat deposited in the target
was 0.96 kW for a beam spot size with a diameter and rotation speed of 1 mm and 10 rpm, respectively. The maximum beam spot temperature is approximately 118◦ C.

cooling water was ﬁxed at 25◦ C. The heat transfer coefﬁcient, calculated by JAERI formula,7) was found to be
10.5 kW/m2 K at 25◦ C. Because the beam spot temperature varied with time, the temperature-dependent thermal conductivity of Be and Al was used for temperatures
between 25 and 1200◦ C and 25 and 700◦ C, respectively.
In our simulations, the heat source was ﬁxed and thetarget model moved across it based on the mass transport option of ANSYS. To capture the eﬀect of temperature variation occurring in the model, the applied meshsize must be small enough. Although the beam spot temperature became constant after several rotations, thiscomplex model required a few hours of the CPU time.
The initial analysis was performed with low rotational
speed, from 1 to 10 rotations per minute (rpm), in several
steps to conﬁrm the reliability of our simulation code.
The present status of simulated heat distribution with
10 rpm is reported in Fig. 2. Further simulation studies
are under way to optimize a small mesh size that canincrease the rotation speed of the disk target up to therequired velocity of 100 to 1000 rpm.
References

Fig. 1. Cooling-water is introduced to the aluminum disk
through a double-piped shaft.
∗1∗2

RIKEN Nishina Center
Facility for Rare Isotope Beams, Michigan State University

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) ANSYS, Inc. Product Release 19.0, USA.
4) A. Yoshida et al., RIKEN Accel. Prog. Rep. 35, 152 (2002).
5) A. Yoshida et al., RIKEN Accel. Prog. Rep. 37, 295 (2004).
6) O. Tarasov et al., Nucl. Instrum. Methods Phys. Res. B
266, 4657 (2008).
7) J. Boscary et al., Fusion Eng. Des. 43, 147 (1998).

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RIKEN Accel. Prog. Rep. 52 (2019)

Primary beam intensity calibration method using charge-states
distribution
D. S. Ahn,∗1 H. Suzuki,∗1 N. Fukuda,∗1 Y. Shimizu,∗1 H. Takeda,∗1 K. Yoshida,∗1 Y. Yanagisawa,∗1 N. Inabe,∗1
and T. Kubo∗2,∗1
The primary beam intensity is an important quantity
for experiments to obtain the production cross-sections
and rates of radioactive isotopes and monitoring the stability of beam during the experiment. The primary beam
intensity is determined using a triple coincidence (3-coin)monitor1) by detecting light charged particles recoilingout of the production target in the BigRIPS, as shownin Fig. 1. The advantage of this system is the nondestructive method and its availabillity at all times during
the experiment but the calibration for 3-coin monitor isneeded and depends on the combination of beams, targets, and beam energy.
The direct measurement of Faraday cup (FC) readout is used for the calibration of the 3-coin monitor. The
size of FC at the BigRIPS is small owing to the space
limitation in the production target chamber, causing escape of the secondary electrons from the FC, even if theelectric suppressor is applied. Consequentially, the readout of FC gives a larger current in cases of heavy-ion
primary beams. Therefore, the determination of FC calibration factor (FCF) is quite important to obtain absolute primary beam intensity. In this report, the calibration method of the primary beam intensity for FC
using a charge-states distribution of the primary beam isreported.
Figure 2 shows the ﬂow chart for the calibration
method of the primary beam intensity for a 238 U86+
beam case. In principle, the beam current can be determined by counting the number of incident ions. The
primary beam is irradiated to the target and measuresthe charge-states distribution after the target. The total
number of incident ions is obtained from the number of
one arbitrary charge-state and its ratio to the total. A
1 mm Be target is used to measure the charge-states distribution of 238 U at 345 MeV/nucleon (such a thin target is preferable to reduce the possible backgrounds ofﬁssion fragments). In the experiment, each charge-state
was set to the central axis in each time. The relative yieldFig. 1. Schematic view of the primary beam monitoring system at the production target chamber.
∗1∗2

RIKEN Nishina Center
FRIB/NSCL, Michigan State University

Fig. 2. Flow chart for the calibration method of the primarybeam intensity.

Fig. 3. Experimental charge-states distribution of 238 U after
1 mm Be target.

for the neighboring ionic charge-state was obtained with
PPACs at F1 or plastic scintillator at F2 and it as normalized with the total number of counts. Figure 3 shows
the charge-state distribution of 238 U after 1 mm Be target in the range from 92+ to 85+ . The number of 86+
charge-states, N (86+ ), and its ratio, R(86+ ), after the
1 mm Be target were deduced and the sum of ratio was
nomarlized with 1. The intensity of the primary beamcannot be measured directly with the BigRIPS detectors
because it has a signiﬁcantly higher rate. The countablecount rate of N (86+ ) was used to deduce the primarybeam intensity whose ratio R(86+ ) was 8.2 × 10−6 . The
number of 86+ charge-state was ∼104∼5 Hz with the full
beam intensity (50∼100 pnA in a U beam case). Thus,
we obtained the beam intensity by the 3-coin monitor,I(3-coin, Be 1 mm).
Consequentially, the FC calibration factor [FCF] was
deduced by comparing the read-out of FC [FCread-out ]and I(3-coin, Be 1 mm), the average value of FCF is 3.2
in the 238 U86+ beam case. Similar types of calibration
were performed in diﬀerent primary beam cases. The average values of FCF are 1.7, 1.55, and 1.3 for a 124 Xe54+ ,78
Kr36+ , and 70 Zn30+ beam at 345 MeV/nucleon, respectively. The FCF is assumed to be 1.0 in the 48 Ca20+ and18 8+
O beam cases.
Reference

1) Y. Yamaguchi et al., RIKEN Accel. Prog. Rep. 42, 161 (2009).
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RIKEN Accel. Prog. Rep. 52 (2019)

Angle-tunable degrader system for OEDO
J. 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

∗1
∗2
∗3
∗4

Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center
Department of Advanced Energy Engineering Science,
Kyushu University
Department of Physics, University of Tokyo- 134 -

Fig. 1. Picture of the angle-tunable degrader system.
100

Arbitrary Unit

An angle-tunable degrader system was developed
for the OEDO beamline,1) which slows down a beam
separated by BigRIPS2) to produce a beam of 10–
50 MeV/nucleon. This system is used as a monoenergetic degrader to reduce the beam energy and its
spread. Since the system was designed to adjust its
wedge angle and thickness, it has high versatility todeal with various experimental conditions. In this report, we present the structure and experimental veriﬁcation of the system.
The degrader part consists of a pair of Al sheetswith quadratic cross sections, and their quadratic coeﬃcients for thickness diﬀer only in their signs. Theiroverlap, therefore, functions as the wedge degrader,
and the wedge angle is changed according to their relative position. The thickness can be also adjusted
by introducing an additional plate. The overall system was constructed as shown in Fig. 1, which has
a ﬁxed central thickness of 3 mm and a wedge angle from 0 mrad to 40 mrad. The eﬀective area is± 30 mm(H) × ± 50 mm(V). The averages of thickness deviations from the machining precision for each
Al sheet are 33 and 58 μm, respectively. The uncertainty of the angle originating from these deviations is
2 mrad.
The commissioning experiment of this system
was carried out at the OEDO beamline.1) 79 Se of
171 MeV/nucleon, separated by BigRIPS,2) was delivered to the degrader system installed at the dispersive FE9 focus. The central thickness of the system
was set to 6 mm to slow down the beam to about
40 MeV/nucleon.
The spread of the outgoing energy distribution forthe monoenergetic-beam case with an optimized wedge
angle was compared with that for the case using the homogeneous degrader, where the wedge angle is 0 mrad,to evaluate the performance of the degrader system.
As shown in Fig. 2, while the energy spread in the homogeneous case was measured to be 12.6 MeV/nucleon
in full width at half maximum, the spread was reduced
to 5.4 MeV/nucleon in the case of the optimized monoenergetic degrader, which is consistent with the estimation by a simulation.
In summary, we developed an angle-tunable degrader system for the OEDO beamline for a low-energy

Homogeneous
Monoenergetic

80
60

FWHM =
5.4 MeV/u40

12.6 MeV/u

20
0
−30

−20

−10

0

10

20

30

Outgoing Energy Deviation (MeV/u)

Fig. 2. Distributions of the outgoing energy deviation using
a homogeneous degrader (black) and an optimized monoenergetic degrader (red). All the distributions werenormalized to have the same number of events.

RI beam. The performance of the system was experimentally veriﬁed using 79 Se beam at 171 MeV/nucleon,
and we successfully obtained a low-energy beam at
42 ± 2.7 MeV/nucleon with the suppressed spread.
We expect that this system can be used for various
purposes and conditions thanks to its ﬂexible wedge
angle.
This work was funded by ImPACT (Impulsing
Paradigm Change through Disruptive Technologies)
Program of Council for Science, Technology and Innovation (Cabinet Oﬃce, Government of Japan).
References
1) S. Michimasa, et al., Prog. Theor. Exp. Phys., accepted.
2) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Development of dispersion-matching optics of primary beamfor SRC-BigRIPS system
S. Y. Matsumoto,∗1,∗2 D. S. Ahn,∗1 N. Fukuda,∗1 N. Fukunishi,∗1 H. Geissel,∗3 N. Inabe,∗1
K. Itahashi,∗1 K. Kusaka,∗1 T. Nishi,∗1 Y. Shimizu,∗1 T. Sumikama,∗1 H. Suzuki,∗1 M. Takaki,∗4
H. Takeda,∗1 Y. K. Tanaka,∗1,∗3 T. Uesaka,∗1 Y. Yanagisawa,∗1 and K. Yoshida∗1
We are working toward the development of a new optics1) for SRC-BigRIPS system that can be used for
two types of experiments based on missing-mass spectroscopy: search double Gamow-Teller giant resonanceand systematic high-precision spectroscopy of pionic
atoms (piAF). In these experiments, the largest contribution to the missing-mass resolution is the momentum spread of the primary beam. Therefore, we applied a technique for dispersion matching2,3) to suppress the contribution from the momentum spread. The
dispersion-matching condition is fulﬁlled when the dispersions of the BigRIPS spectrometer and its upstream
beam-transfer lines are properly adjusted to eliminate
the contribution factor as follows:(xF5 |δF0 ) + (xF5 |xF0 )(xF0 |δSRC ) = 0.

5

×103

CountsCountsHere, x is the horizontal position and δ is the relative
momentum deviation from a reference particle.
In constructing the dispersion-matching optics, we investigated phase distributions of beam transfer-line, i.e.,
the upstream section between SRC and F0. In the preceding piAF experiment,4) the dispersion in SRC-F0 was
not properly controlled owing to insuﬃcient information
regarding SRC. In addition, we require momentum compaction (ideally achromatic-focus) condition at the intermediate point (T11), thereby isolating the uncertainties
in the optical properties of the in-coming beam and de-

4

×103
5
4

3

3

2

2

1

1

0

-15 -10-50
5xF5 [mm]0-15 -10-50
5xF5 [mm]Fig. 1. Position distribution at F5 with the standard (left)and dispersion-matching (right) optics. Red and bluelines represent data with or without target at F0, respectively.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Department of Physics, Kyoto University
GSI Helmholtzzentrum für Schwerionenforschung GmbH
Center for Nuclear Study, University of Tokyo

Table 1. Measured and designed matrix elements.
Matrix element(xF5 |δF0 )(xF5 |xF0 )(xF0 |δSRC )Measured value
62.3 ± 0.5 mm/%−1.67 ± 0.03
29.1 ± 0.3 mm/%

Designed value
62.0 mm/%−1.82
33.4 mm/%sign T11-F0 by realizing ﬂexible designs at F0.
To deduce the phase distributions at T11 and F0, we
used particle trajectories measured by detectors in BigRIPS and traced them back to the upstreams. The
matrix elements in T11-F0 and BigRIPS required forthe trace-back method are measured by decoupling thecorresponding sections by inserting thick degraders at
the entrances.
We performed an experiment to examine the beamtransfer line in June 2018. The goal of this experiment isto achieve the dispersion-matching condition by tuning
the optics in the beam-transfer line. A primary beam of
18 8+
O with an energy of 230 MeV/nucleon was utilized
up to F7 to measure the optical matrices. The beam
was detected by PPACs at F3, F5, and F7. According
to the measurements, we optimized optics in the beamtransfer line to ensure that T11 and F0 have momentum
compaction and dispersion, respectively.
We evaluated the resolving power of the dispersionmatching optics by simulating the reaction Q-value by
the energy loss at F0. Figure 1 shows a comparisonof position distributions at F5 measured with an Al(75 µm thickness) target represented by red curves and athrough-hole represented by blue curves for the standard
optics (left panel) and the dispersion-matching optics(right panel). The right panel seemed to exhibit better separation with diﬀerence in energy loss of 4.2 MeV.
Table 1 presents the measured and designed values ofmatrix elements related to the dispersion-matching condition. Consequently, we succeeded in separating δ =0.056% of momentum deviations in 3.6σ. The corresponding resolving power is estimated to be 7300.
In summary, we constructed a new optical system
to improve the missing-mass resolution by dispersion
matching. A precise analysis is in progress.
References

1) T. Nishi et al., in this report.
2) B. L. Cohen, Rev. Sci. Instrum. 30, 415 (1959).
3) T. Wakasa et al., Nucl. Instrum. Methods Phys. Res. A
482, 79 (2002) and references therein.
4) T. Nishi et al., RIKEN Accel. Prog. Rep. 48, 235 (2015).

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RIKEN Accel. Prog. Rep. 52 (2019)

SHE-Mass-II: an MRTOF-MS for Super Heavy Nuclei
M. Wada,∗1 P. Schury,∗1 S. Kimura,∗2 S. Ishizawa,∗2,∗5 T. Niwase,∗2,∗3 Y. Ito,∗4 M. Rosenbusch,∗2 D. Kaji,∗2
K. Morimoto,∗2 H. Haba,∗2 H. Miyatake,∗1 X. Y. Watanabe,∗1 H. Hirayama,∗1 J. Y. Moon,∗7,∗1 A. Takamine,∗2
T. Tanaka,∗3,∗2 K. Morita,∗3,∗2 H. Ishiyama,∗2 and H. Wollnik∗6
The SHE-Mass facility was a system with a multireﬂection time-of-ﬂight mass spectrograph (MRTOFMS)1) and a cryogenic gas catcher coupled with the
GARIS-II at RILAC. With this setup, we have measured the masses of more than 80 fusion-evaporated
products including several trans-fermium nuclides.2–5)
After the shutdown of GARIS-II at RILAC, we rebuilt a similar setup, i.e., the SHE-Mass-II, at the new
GARIS-II in the E6 experimental room.
The new setup has a single stage triplet ion trapsystem, which directly connects the gas catcher to the
MRTOF to achieve high eﬃciency. The whole setup
including vacuum pumps, a gas cylinder, and electric
circuits is mounted on a single base plate and the plate
is movable on rails to ensure quick coupling and decoupling to the GARIS-II. The gas catcher and ion
trap chambers are mounted on a two-dimensional railsystem that enables easy maintenance of the internal
structures of the setup.
A drawback of the new setup is that more contaminant ions could be expected owing to a diﬃculty ofintermediate mass selection. In the previous setup, we
had a 5 m-long beam line between the two ion traps
where we could place a Bradbury-Nielsen (BN) ion
gate6) to select a single mass number. However, the
new setup has only a 50 cm distance between the trapand MRTOF where a BN gate can be installed. We
developed a 10 times ﬁner gate device made of 13 µthick wires with 130 µ intervals, which can deﬂect a
1 keV/q ion beam by 65 mrad with a ±100 V pulse.
Such ﬁne structure makes sharp cut on the ion beam.
In a preliminary test, a resolution of 2 mass units wasachieved.
Another improvement in the new setup is the replacement of a sextuple ion beam guide (SPIG) madeof rigid molybdenum rods with a segmented micro
quadrupole ion beam guide (SµQPIG) made of 2 mmwide, four-layer printed circuit boards. These devices interface the gas catcher with the triplet ion trap
through diﬀerential pumping sections. In the previous
setup, we needed to run an ion source in the gas catcher
to have a ‘space-charge cloud’ which pushed the ionsin the SPIG, while in the new setup, a DC gradientpotential in the SµQPIG carries the rare ions without
∗1
∗2
∗3
∗4
∗5
∗6
∗7

KEK, Wako Nuclear Science Center
RIKEN Nishina Center
Department of Physics, Kyushu University
JAEA
Department of Physics, Yamagata University
Department of Chemistry and Biochemistry, New Mexico
State University
Institute for Basic Science, Rare Isotope Science Project- 136 -

Fig. 1. SHE-Mass-II setup.

support from the space-charge cloud. The new scheme
provides cleaner ion beams to the MRTOF.
We also replaced the time-of-ﬂight detector with a
newly developed α-TOF detector, which records thetime-of-ﬂight signal and the successive α-decay, simultaneously. The ﬁrst online commissioning of the SHEMass-II setup was performed in December 2018 and
we found that the α-TOF detector signiﬁcantly reduced the background level.7) An oﬄine experimentusing 252 Cf ﬁssion source is also in progress.
We are ready to start the direct mass measurementof hot-fusion super heavy elements, 288 Mc and 284 Nh,with the SHE-Mass-II setup.
References
1) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B
335 39, (2014).
2) P. Schury et al., Phys. Rev. C 95, 011305(R) (2017).
3) S. Kimura et al., Int. J. Mass Spectrom. 430, 134 (2018).
4) M. Rosenbusch et al., Phys. Rev. C 97, 064306 (2018).
5) Y. Ito et al., Phys. Rev. Lett. 120, 152501 (2018).
6) N. E. Bradbury, R. A. Nielsen, Phys. Rev. 49, 388 (1936).
7) T. Niwase et al., RIKEN Accel. Prog. Rep. 51, 157 (2018).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Status and future plans of the MRTOF MS constructed at the SLOWRI
facility
M. Rosenbusch,∗1 M. Wada,∗1,∗2 H. Ishiyama,∗1 P. Schury,∗2 Y. Ito,∗3 H. Haba,∗1 S. Ishizawa,∗1 D. Kaji,∗1
S. Kimura,∗1 H. Miyatake,∗2 J. Y. Moon,∗4 K. Morimoto,∗1 K. Morita,∗1,∗5 T. Niwase,∗1,∗5 A. Takamine,∗1
T. Tanaka,∗1,∗5 and H. Wollnik∗6
A new multi-reﬂection time-of-ﬂight mass spectrograph (MRTOF MS) for the precise measurement of nuclear masses has been assembled at the SLOWRI facility
at RIKEN. The device is designed and sized following
the successful apparatus1–4) presently installed at thegas-ﬁlled ion-recoil separator GARIS-II. Two concentric
ion mirrors separated by a central drift tube of 26 cm
length are facing each other, where each mirror consistsof eight electrodes enabling deceleration and reﬂectionof ions and two electrostatic lenses enabling radial conﬁnement (length of each mirror: 35 cm, total length of
MRTOF MS: 96 cm). For mass resolving powers in theorder of m/δm > 105 (m as the mass and δm as measured FWHM of the mass according to the TOF signal),
ion-optical aberrations must be reduced accordingly toallow for a narrow time-of-ﬂight focus. Several measures
have been undertaken: As radial aberration coeﬃcientsfrom initial angles and diameters of the beam decrease
rapidly with the diameter of the ion optics, the electrode diameter has been chosen as large as 10 cm, while
the beam diameter is expected to be at the order of amillimeter for the major part of the trajectory. All electrodes consist of precision-machined stainless steel (providing high stability), and have been coated with gold toensure an excellent electric-ﬁeld distribution in the absence of chemical compounds bound to the surfaces. The
electrodes are further mounted on a precision-machined
single solid piece of alumina, where the position of theelectrodes (concentric on the outer side as well) is deﬁned
by a V-shape of the ceramic support (see photo). Oneof the technical goals of this setup is the acceptance andstorage of ions with kinetic energies of 5 keV or above
present at the position of the drift tube. In presently
well-known and successful conﬁgurations of the electricﬁelds (for positive ions), this requires negative voltagesof up to −15 kV at the electrostatic lenses (the broad
electrodes at each mirror). Thus, special attention has
been given to the choice of the electric feedthroughs,
distances of cables, and vacuum compatible insulationof the wires. The wires inside the vacuum allow for biases of more than 10 kV at zero distance between each
two cables. The vacuum system of the MRTOF MS device is presently operational, and ion traps for guidance
and preparation of radioactive ions are existing and to
∗1
∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), IPNS, KEK
Advanced Science Research Center, JAEA
Institute for Basic Science
Department of Physics, Kyushu University
Department of Chemistry and Biochemistry, New Mexico
State University

Fig. 1. Top: Photo from the top showing the assembly with
gold-coated electrodes. Bottom left: Precision machined
ceramic support with V-shape to define the electrode position. Bottom right: Cabling of the electrodes for the
suppression of electric discharges.

be installed in near future.
The new MRTOF device has been constructed fortwo major purposes, which is a coupling to the gas
cell presently developed for SLOWRI5) to operate insymbiosis with other BigRIPS experiments, and the development and test of novel technologies for MRTOF
mass spectrometry. In collaboration with experimental groups operating at BigRIPS, a new project of the
SLOWRI facility aims at the installation of a cryogenic
helium gas cell at the end of the BigRIPS beam line
to accept unused reaction products measured at various
in-beam experiments, which are guided to beam dumps
otherwise. Application of state-of-the-art technologies
as using the in-trap lift technology6) and an in-trap deﬂector7) are further planned for the MRTOF MS operation at SLOWRI in future.
References

1) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B
376, 425 (2015).
2) P. Schury et al., Int. J. Mass Spectrom. 359, 19 (2014).
3) Y. Ito et al., Phys. Rev. Lett. 120, 152501 (2018).
4) M. Rosenbusch et al., Phys. Rev. C 97, 064306 (2018).
5) A. Takamine et al., in this report.
6) R. N. Wolf et al., Int. J. Mass Spectrom. 313, 8 (2012).
7) P. Fischer et al., Int. J. Mass Spectrom. 435, 305 (2012).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Development of multiple reflection time of flight mass spectrograph at
KISS
J. Y. Moon,∗1 S. C. Jeong,∗1 M. Wada,∗2 P. Schury,∗2 Y. X. Watanabe,∗2 Y. Hirayama,∗2 Y. Ito,∗6
M. Rosenbusch,∗3 S. Kimura,∗3 S. Ishizawa,∗5 T. Niwase,∗4 H. Wollnik,∗7 and H. Miyatake∗2
KEK Isotope Separation System (KISS) dedicated tothe study of the third peak around A ∼ 195 in thesolar abundance can produce pure low-energy beamsof neutron-rich isotopes around N = 126 using multinucleon transfer reaction and in-gas cell laser ionizationand spectroscopy technique.1)
The KISS facility mainly performing beta-decay lifetime study and beta-delayed γ-ray spectroscopy so far,by a multi-reﬂection time-of-ﬂight (MRTOF-MS), will
be able to measure masses of RIs by steering the beam
direction toward the MRTOF-MS system while the betadecay curve is being measured at the decay station. The
MRTOF-MS, competitive to the state-of-art Penning
trap, features a high mass resolving power of >100000
even in the short measurement time (∼30 ms). Together
with its lower yield requirement, remarkable strengths
the device has are suitable for the short-lived RIs of low
production yield.2)
Recently, construction of a new MRTOF-MS has been
completed (Fig. 1), and presently in the performance
test. It consists of a gas cell to cool down the injected
ions, a trap system, and a MRTOF chamber. The trapsystem thermalizes the ions, and converts a continuous

Fig. 1. MRTOF-MS system, constructed and coupled to the
KISS beam line.
∗1
∗2

∗3
∗4
∗5
∗6
∗7

Institute for Basic Science, Rare Isotope Science Project
Wako Nuclear Science Center (WNSC), Institute of Particle
and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)
RIKEN Nishina Center
Department of physics, University of Kyushu
Department of physics, University of Yamagata
JAEA
Department of Chem. & Bio.chem. New Mexico state university

Fig. 2. Ion currents measured at the outer-ring and the faraday cup, respectively for the diﬀerent pressures – (A) PHe= 100 Pa, (B) PHe = 174 Pa.

beam into a pulsed beam for further MRTOF operation.
In this report, for the gas cell ﬁlled with the helium
buﬀer gas, its ion extraction eﬃciency experimentallymeasured has been briefed. The investigation has been
performed at two diﬀerent pressures of PHe = 100 and
174 Pa. Using a radio frequency (RF) carpet (ϕ190 mm)
with a pitch of 0.64 mm, an exit hole with ϕ1.28 mm anda thermal K+ ion source. The “ion surﬁng” mode developed by the combination of a repelling RF potential,
a DC potential gradient, and a 4-phase audio frequency(AF) potential has been implemented, by which the ionsstopped in the gas cell are quickly transported.3) Whenthe ion surﬁng mode with ion drift direction opposite
to the exit hole applied, the current measured at theoutermost ring of RF carpet (Iouter ) showed only small
diﬀerence of around 1%, compared to that at the carpet
surface of no RF applied. A faraday cup was installednear the exit, whose current is IFC . Figure 2 shows theevidence of the ion surﬁng mode created, in which therelative phase of AF voltages was changed by time from+90◦ (to exit hole) to −90◦ (to outer-ring). It has beenachieved that most of ions arrived on the carpet wereextracted by the “ion surﬁng” mode, i.e. the ratio of theextracted ions to the collected (“extraction eﬃciency”)
close to 100%.
References

1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res. B
353, 4 (2015).
2) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B
335, 39 (2014).
3) G. Bollen, Int. J. Mass Spectrom. 335, 131 (2011).

- 138 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Oﬄine test for RF carpet transportation in RF ion guide gas cell at the
SLOWRI facility

We are developing an RF ion guide1) gas catcher
cell (RFGC) at the SLOWRI facility. Instead of thepreviously-used cylindrically shaped gas cell, we recently
introduced a newly-designed cuboid-shaped gas cell to
improve the heat conduction between the cell and a cryocooler. At the same time, we redesigned an RF carpet(RFCP) conﬁguration consisting of two stages of RFtransport electrodes, which is one stage less than thatin the previous version3) (see Fig. 1). Although the 1st
RFCP has been unchanged, the 2nd RFCP now has concentric electrodes to collect ions to the exit hole at thecenter of the RFCP (Fig. 1(b)). Since the RFCPs aremounted onto the lid (an aluminum plate) of the gas
cell, the thermal conductance has been improved andthe RFCPs are eﬃciently cooled down.
We tested the transport performance of the RFGC using a surface ionization Cs ion source placed at the innerwall of the gas cell. The 1st RFCP carries ions to the
2nd RFCP, and the ions are guided to the exit hole by
the 2nd RFCP. Firstly, we measured the ion currents collected onto the 1st RFCP by using the 1st RFCP as a
Faraday cup, and then transported the ions through the
1st RFCP. After that, the ions were transported to the
(a)

(b)

Fig. 1. (a) Sketch of the RFGC with an ion trajectory (greenline). Red lines depict equipotential surfaces. (b) Photoof the center region of the RFCPs.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Quantum Metrology Laboratory, RIKEN
Wako Nuclear Science Center (WNSC), IPNS, KEK
Institute for Basic Science

Transport efficiency on 1st RFCP

A. Takamine,∗1 M. Rosenbusch,∗1 M. Wada,∗1,∗3 P. Schury,∗3 J. Y. Moon,∗4 T. Sonoda,∗1 T. M. Kojima,∗1
I. Katayama,∗1 Y. X. Watanabe,∗3 H. Ueno,∗1 and H. Ishiyama∗1
0.79.35 kPa
13 kPa18.8 kPa

0.6
0.5
0.4
0.3
0.2
0.1
0

0

20

40

60

80

100

120

140

160

RF voltage on the 1st RFCP [Vpp]Fig. 2. 1st RFCP transportation test results for three different He gas pressures, namely 9.35 kPa, 13 kPa, and18.8 kPa. In this test, the drag dc field on the 1st RFCP
was 11.7 V/cm and the extraction DC field between the
1st and 2nd RFCPs was 20 V/cm.

2nd RFCP by applying the RF and DC ﬁelds to the 1st
RFCP. The eﬃciency was deﬁned by the current measured at the 2nd RFCP divided by that measured at the
1st RFCP. The test was typically performed with currents in the order of a few nA at the 1st RFCP. Figure 2
shows one example of the obtained transport eﬃciency
as a function of the RF voltages applied to the 1st RFCP
for three diﬀerent helium gas pressures. The results show
a transport eﬃciency of ≈60% at pressures of 13 kPa andless.
We subsequently extracted the ions from the exit holeusing an ion surﬁng technique4) on the 2nd RFCP, andthe extracted ions were detected by a Faraday cup behindthe 2nd RFCP. The extraction eﬃciency was measured tobe ≈ 80%. Therefore, the total eﬃciency in the present
RFCP conﬁguration was obtained to be ≈50%.
We will continue the test for an RFCP with ﬁner
pitch, and will try to use an ion surﬁng type RFCP
as the 1st RFCP instead of the DC+RF type used inthis measurement. We are now preparing the ion-guidesystem to be placed behind the 2nd RFCP; it consistsof a quadrupole ion beam guide and an ion trapping
system. This low-energy RI beam provider will be connected to a multi-reﬂection time-of-ﬂight mass spectrograph (MRTOF-MS). We plan to start online commissioning of the RFGC in FY2019 at the end of the ZeroDegree beam line.
References

1) M. Wada et al., Nucl. Instrum. Methods Phys. Res. B 204,570 (2003).
2) A. Takamine et al., RIKEN Accel. Prog. Rep. 50, 194 (2017).
3) A. Takamine et al., RIKEN Accel. Prog. Rep. 50, 193 (2017).
4) G. Bollen, Int. J. Mass Spectrom. 299, 131 (2011).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Study of extraction yield of multi-nucleon transfer reaction products byusing cooled argon gas cellY. Hirayama,∗1 Y. X. Watanabe,∗1 M. Oyaizu,∗1 M. Ahmed,∗1,∗2 H. Choi,∗3 S. Iimura,∗4 H. Ishiyama,∗5
S. C. Jeong,∗6 Y. Kakiguchi,∗1 J. Y. Moon,∗6 M. Mukai,∗2 P. Schury,∗1 M. Wada,∗1 and H. Miyatake ∗1

∗1

∗2
∗3
∗4
∗5
∗6

Wako Nuclear Science Center (WNSC), Institute of Particle
and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK)
Department of Physics, University of Tsukuba
Seoul National University
Osaka University
RIKEN Nishina Center
Institute for Basic Science, Rare Isotope Science Project136

Xe beamLaser
ionization+

Purified Ar gas~ 0.1 ppb

198

Pt rotating target
PT100

+

gas jetLiq. N2

30 Pa

10 Pa

Doughnut-shaped
argon gas cellHe cryo module−4

Fig. 1. Schematic view of the gas cell system with a coolingsystem. The details of the gas cell system were reported
in Ref. 2).
250

Counts

200
150
100
50

30 kPa

0
0

10

20

15 kPa
30 kPa
30

40

50

60

70

80

90

60

70

80

90

Time (min.)350

Temperature (K)We have developed the KEK Isotope Separation
System (KISS) to study the β-decay properties ofneutron-rich isotopes with neutron numbers around N =126 for astrophysics research.1) KISS uses a laser ion
source to produce pure low-energy ion beams of theisotopes, which are produced as target-like-fragments(TLFs) in multi-nucleon transfer reactions by impinging
a stable 136 Xe beam with an energy of approximately
10 MeV/nucleon on a 198 Pt target. The extraction efﬁciency from the laser ion source, which is based on anargon gas cell, was as low as 0.1%.2) We assume thatthe low extraction eﬃciency stems from the formationof molecule ions between TLF ions and impurities in thegas cell. The molecule ions would be neutralized in theargon gas cell, and, therefore, we cannot conﬁrm the formation of neutral molecules by detecting and identifying
them using usual electromagnetic methods.
To study this assumption, we developed a cooling system for the argon gas cell to freeze out the impurities
in the argon gas and gas cell for suppressing the formation probability. Figure 1 shows a schematic view ofthe gas cell system with a cooling system that consistsof a He cryo-module and liquid nitrogen cooling circuit.
The gas cell is on the module to be cooled eﬀectively,
and liquid nitrogen is ﬂowed along a wall of the gas cell.
Two thermometers (Pt100) were installed to monitor thetemperatures at the center and the argon gas inlet partof the gas cell. The cooling system enabled the argon
gas and the gas cell to be cooled down to approximately
120 K in an oﬀ-line cooling test.
To study whether the extraction yield could be increased by suppressing the formation probability ofmolecules using the cooling system, we performed
an on-line experiment using a 136 Xe20+ beam with10.75 MeV/nucleon and an intensity of 20 pnA. Figure 2
shows the measured extraction yield of 198 Pt+ (top) andthe temperatures (bottom) as a function of time, respectively. The red and blue lines in the bottom ﬁgure show
the temperatures at the center and the gas inlet partof the gas cell, respectively. The extraction yield decreased with decrease in the temperature, and becamealmost saturated at 60 min with temperatures of 170 K
and 130 K at the center and the gas inlet part of thegas cell, respectively. The origin of bumps measured
at approximately 26 and 36 min in the top ﬁgure was

300
250
200
150
100
50
0
0

10

20

30

40

50

Time (min.)Fig. 2. Measured extraction yield of 198 Pt+ (top) and thetemperatures (bottom) as a function of time.

unclear. After saturation, we decreased the argon gas
pressure down to 15 kPa from 30 kPa to keep the gas
density constant according to the change in temperature. After that, we found a recovery of the extraction
yield.
However, we did not ﬁnd any increase in the extraction yield by cooling the gas cell system. This indicates that the formation of molecules is not the dominant cause for the low extraction yield. The extraction
yield of unstable 199 Pt at 170 K was also the as same asthat measured at room temperature.
References

1) S. C. Jeong et al., KEK Report 2010-2, (2010).
2) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res. B
412, 11 (2017).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Yield analysis using target sliding system at KISS

∗1

∗2
∗3
∗4
∗5
∗6
∗7

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

Experimental data
GRAZING simulation

1.5

1

0.5

0
0

5
10
15
20
25
30
Distance between target and window (mm)

2

1

0
50

60
70
Angle (degree)

80

11
10
9
8
7
6
5
4
3
2
1
0

Yield (a.u.)

Fig. 1. Yields of 199 Pt by changing the distance between thetarget and the window.

Energy (MeV/nucleon)

We are developing KEK Isotope Separation System (KISS)1) to perform the β-γ spectroscopy ofneutron-rich nuclei around the neutron-closed shell N =126, relevant to the r-process nucleosynthesis. The
neutron-rich nuclei are produced by multinucleon transfer (MNT) reactions between the 136 Xe beam and 198 Pt
target,2) and collected by a gas cell ﬁlled with argon
placed at the downstream of the target. Because thedense plasma in the argon gas induced by the primarybeam would reduce the extraction eﬃciency for the ionsof interest, the gas cell has a beam pipe through which
the primary beam passes without entering the gas cell.3)
Thus the target-like fragments (TLFs) ejected from thetarget at ﬁnite angles can enter the gas cell through thedoughnut-shaped 5 µm Kapton window with the innerand outer diameters of 20 and 90 mm, respectively. To
optimize the distance between the target and window,
which is important for the eﬃcient collection of TLFs, atarget sliding system was introduced that can move thetarget along the beam axis and extraction yields werestudied by changing the distance.
In this work, the TLFs of interest were 199 Pt isotopes,
which were produced in the MNT reactions of 136 Xeand 198 Pt. The beam was provided by RILAC2 + RRC
with an energy of 9.4 MeV/nucleon on the target andthe target thickness was 12.5 mg/cm2 . 199 Pt isotopes
entering the gas cell were thermalized and neutralized in
the argon gas and transported to the exit of the gas cellby a laminar gas ﬂow. They were irradiated by lasers tobe element-selectively ionized and accelerated by a highvoltage of 20 kV. After mass-separated by an dipole
magnet, they were implanted into an aluminized Mylartape, where their β-rays were detected to evaluate theimplantation rate by ﬁtting the decay curves.
The dots in Fig. 1 show the measured extraction
yields by changing the distance between the target andthe window. Figure 2 shows the correlation between
energies and angles of the 199 Pt TLFs by the GRAZING calculations.4) The yields show a wide distribution
with a maximum at the energy around zero and angle
around 70◦ . The red line in Fig. 1 indicates the 199 Pt
yields considering the calculated correlation in Fig. 2

Implantation rate (a.u.)

Y. X. Watanabe,∗1 Y. Hirayama,∗1 M. Mukai,∗2 H. S. Choi,∗3 S. Iimura,∗4 Y. Kakiguchi,∗1 H. Miyatake,∗1
M. Oyaizu,∗1 P. Schury,∗1 M. Wada,∗1 A. Taniguchi,∗5 S. C. Jeong,∗6 N. Ishiyama,∗7 M. Ahmed,∗2 andJ. Y. Moon∗6

Fig. 2. Correlation between energies and angles of 199 Pt nuclei ejected from the target in MNT reactions of 136 Xe(9.4 MeV/nucleon) + 198 Pt (12.5 mg/cm2 ) by GRAZING calculations.

with the beam spot size (ϕ6 mm) on the target. It is
normalized in the experimental data at a distance of
10 mm. These calculations were found to be signiﬁcantly consistent with the experimental data and they
provide a good reference for the optimization of target
position.
References

1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 376, 52 (2016).
2) Y. X. Watanabe et al., Phys. Rev. Lett. 115, 172503(2015).
3) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 412, 11 (2017).
4) A. Winther, Nucl. Phys. A 572, 191 (1994); 594, 203(1995).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Present status of ERIS at the SCRIT electron scattering facility
T. Ohnishi,∗1 S. Ichikawa,∗1 M. Nakano,∗2 K. Kurita,∗2 and M. Wakasugi∗1
The electron-beam-driven RI separator for SCRIT(ERIS)1) at the SCRIT electron scattering facility2) isan online isotope separator system used to produce lowenergy RI beams for electron scattering experiments ofunstable nuclei. Recently, we developed ion-stacking
and pulse-extraction systems to improve the DC-topulse conversion eﬃciency using an RFQ cooler buncher
named FRAC (fringing-RF-ﬁeld activated DC-to-pulse
converter).3) The results were reported in Ref. 4). In
the present year, we have adopted the ion-stacking andpulse-extraction systems to the surface-ionization ion
source to extend the variety of ion beams. In this paper,
we report the results and present the status of ERIS.
Figure 1 shows the schematic of the surface-ionization
ion source at ERIS and its electrical potential. The ionization chamber is made of tantalum, which is 25 mm
long, contains a hole with a diameter of 1.5 mm, and has
inner and outer diameters of 7 and 9 mm, respectively.
The exit grid contains a hole with a diameter of 3 mm
which is attached to a meshed electrode, and it is 3 mm
away from the exit hole of the ionization chamber toavoid thermal deformation. Most of the neutral atoms
remain inside the ionization chamber and transfer tube,
except those that escape through the small exit hole.
The neutral atoms are ionized at the inner wall of theionization chamber. A large electric current is applied
to the ionization chamber through the transfer tube andthe inner wall is heated to 1000–2000◦ C.
The commissioning test was performed using a 133 Cs
ion beam of 10 keV. The voltage of the exit grid at thestacking and extraction were 10 and −60 V, respectively.
An electric current of 120 A was applied to the ionization chamber. The extracted ions were transported to
FRAC and measured by the monitoring system.5) Figure 2(a) shows the pulse shape with a stacking time ofFig. 2. (a) Pulse shape after 10-ms of stacking; the dotted line shows the current of the continuous beam. (b)Stacking-time dependence of stacking ratio.

10 ms. The extraction period was set to 2 ms to measure the pulse shape. With a stacking time of 10 ms, thepulse height was roughly 34 times of that with a continuous beam. The stacking time dependence of stacking
ratio is shown Fig. 2(b). The stacking ratio is the ratioof the charge calculated by subtracting the contributionof the continuous beam from the total charge within aextracted pulse width to the total charge obtained byintegrating the continuous beam over the stacking time.
A stacking ratio of almost 0.9 was obtained at a stackingof 10 ms. In comparison to previous results4) (approximately 0.2 with a 10 ms stacking), the obtained stacking
ratio is much larger. We reason that the number of neutral atoms escaped from the ionizaiton chamber during
the staking time is small owing to the high ionizationeﬃciency.
The DC-to-pulse conversion eﬃciency of FRAC wasmeasured and it exceeded 50% with a longer stacking time of approximately 50 ms. This longer stacking
time was enough to cool the ions with a relatively small
amount of buﬀer gas (∼10−3 Pa)inside FRAC. This operation condition is needed to connect with the SCRIT
device installed inside the electron storage ring. The
results at FRAC were reported in Ref. 6).
More detailed study and improvement of the ion stacking inside ERIS is in progress.
References

Fig. 1. Schematic of the surface-ionization ion source at
ERIS and the electrical potential.
∗1∗2

RIKEN Nishina Center
Department of Physics, Rikkyo University

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. 50, 192(2017).
5) M. Togasaki et al., RIKEN Accel. Prog. Rep. 44, 173(2013).
6) S. Sato et al., in this report.

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Electron-beam-current control at RTM injector
M. Watanabe,∗1 A. Enokizono,∗1 and M. Wakasugi∗1

Beam Current Ie (mA)

100
10Grid voltage Vg
200 V
50 V

1

Cathode heater power Ph = 21.1 W

400Perveance = Ie / Vg

16

18

20

Cathode Heater Power Ph (W)Fig. 1. Electron beam current depending on cathode heater
power. It saturates around the heater power of 20 W.
RIKEN Nishina Center

3/2: 0.2 x 10

-3

300
200
100
0

0

50

100

150

200

Grid Voltage Vg (V)Fig. 2. Electron beam current depending on the grid voltage.
The figure shows the case of cathode heater power of
21.1 W, which is saturated.

graph forms straight lines in the logarithmic y-axis up
to Ph = 18 W. This is a common behavior of cathodetype electron source. In this range, it should be notedthat the electric ﬁeld by Vg does not signiﬁcantly affect the beam current, indicating that the electric ﬁeld
used to extract the electrons does not have a dominanteﬀect on extraction. However temperature plays a signiﬁcant role in the extraction of thermal electrons. Thisis consistent with the exponential functions that produce
straight lines in the logarithmic scale because the Fermi
function is composed of an exponential function.
In contrast, Ie is saturated above Ph = 19 W. This
is interpreted as the space charge between the cathodeand grid manages the maximum beam current because
the space charge suppresses the electron extraction byscreening the electric ﬁeld.
Figure 2 shows the dependence of electron beam current Ie on the grid voltage Vg . It seems that it is easy
to extrapolate the line toward the higher Vg range to
produce a higher beam current Ie . The original designof RTM has a maximum Vg of 200 V. However, we havealready installed a grid voltage power supply of 500 V
for this purpose.
According to these results, the heater power Ph >19 W for the cathode-type electron source NJK2305 is abetter option to obtain a controllable beam current with
Vg < 200 V.
References

0.1
14

∗1

500

Beam Current Ie (mA)

SCRIT facility1) is a unique facility to measure electron scattering oﬀ from short-lived nuclei. In the
SCRIT facility, a racetrack microtron (RTM2) ) is usedas the electron injector of the energy of 150 MeV forthe electron storage ring (SR2) and ISOL-type nuclei
source which is the electron-beam-driven RI separator
for SCRIT (ERIS3) ). We have been working toward upgrading4) the RTM to operate ERIS for eﬃcient photoﬁssion and run SR2 in a stable condition. Especiallyfor ERIS, a higher electron beam current is desired forhigher ion yield of short-lived nuclei.
RTM is equipped with a cathode-type electron sourcewith the energy of 60 keV. Before adjusting and upgrading the RTM accelerator, it is important to know thespeciﬁcations of the 60 keV cathode-type electron sourceof RTM.
It is evident that the electron beam current depends
on the temperature of the cathode, which is controlled
by the cathode heater power Ph and the electric ﬁeld
around the cathode to extract thermal electrons fromthe surface of the cathode. In this study, we examinedthese relationships.
The commercially available NJK2305, provided by
New Japan Radio Co., Ltd., is used as the cathode-type
electron source. The maximum electron beam current is
4.25 A at a heater voltage of 6.3 V. It has a grid meshin front of the cathode surface to make electric ﬁeld forthe extraction of thermal electrons. The beam current
ranges from 20 to 70 mA with a grid voltage of 20 V.
Figure 1 shows the cathode-heater-power Ph dependence of the electron beam current Ie. Unfortunately,
we do not have information about the temperature of
the cathode; however, it is considered that temperatureis nearly proportional to Ph . The two lines in the ﬁgure
represent the grid voltage (Vg ) of 50 and 200 V. The

1) M. Wakasugi et al., Nucl. Instrum. Methods Phys. Res.
B 17, 668 (2013).
2) T. Hori, Doctoral Thesis, the Graduate University for
Advanced Studies (SOKENDAI), 2002.
3) T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B
317, 357 (2013).
4) M. Watanabe et al., RIKEN Accel. Prog. Rep. 49, 188(2015), 50, 190 (2016), and 51, 177 (2017).

- 143 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Modification of dc-to-pulse converter FRAC
S. Sato,∗1,∗2 M. Wakasugi,∗2 T. Ohnishi,∗2 M. Watanabe,∗2 A. Enokizono,∗2 K. Kurita,∗1 and M. Nakano∗1,∗2
At the SCRIT electron scattering facility,1) we aim
at realizing world’s ﬁrst electron scattering experimentfor unstable nuclei, after succeeding in the principle
veriﬁcation experiment using stable nuclei 132 Xe.2) In
order to perform electron scattering with an unstable nuclei with a small production rate, it is important to accumulate and inject ions eﬃciently into the
SCRIT device. For this purpose, it is necessary to convert a continuous ion beam from the ISOL-type ion
separator, ERIS (Electron-beam-driven RI separater
for SCRIT),3) to a pulsed beam with a pulse duration of 300–500 µs. We developed a dc-to-pulse converter, FRAC (Fringing-Rf-ﬁeld-Activated dc-to-pulse
Converter),4) based on an RFQ linear ion trap, with aconversion eﬃciency of 5.6%. In this article, we reportabout the modiﬁcation applied to further improve theeﬃciency and the latest performance of the FRAC.
The ﬁrst modiﬁcation is to enable cooling of the accumulated ions with a buﬀer gas. Ions lose their kinetic
energy by collision with the buﬀer gas and accumulate
in a longitudinal potential well created by the DC potential applied to the RFQ rod and a barrier electrodeat both ends of the rods. The ions are injected for several seconds, stacked, and consequently ejected as ahigh-intensity pulsed beam. Ion beam cooler-buncher
technology with a buﬀer gas of ∼1 Pa is widely usedin the world. However, since the SCRIT device operates under a high vacuum of ∼10−8 Pa, it cannot be
used in our beam line. Therefore, we tried to maintainthe pressure inside the FRAC as high as possible while
keeping the beam line vacuum at ∼10−5 Pa by differential pumping between the FRAC and beam line.
As a result, the vacuum of the FRAC was achievedas ∼10−3 Pa. Cooling with low-pressure buﬀer gas
requires a long cooling time of several tens of milliseconds, which causes a decrease in eﬃciency, however,that can be prevented by operating the FRAC in the
SPI (Synchronous Pulse Injection) mode,4) in which
the injection barrier potential is switched open andclose synchronously with the arrival of the pre-pulsed
beam from ERIS.
The second modiﬁcation is to enable the applicationof an electric ﬁeld gradient in the longitudinal directionof the FRAC. When the potential of the cooling regionis uniform, it takes several milliseconds to extract all
the cooled ions because they are widely distributed in
the entire cooling area with low velocity. Therefore,
the RFQ was physically divided into six segments, anddescending DC potentials were applied and the potential dropped toward the exit. Consequently, the cooled∗1∗2

Department of Physics, Rikkyo University
RIKEN Nishina Center- 144 -

Table 1. Conversion eﬃciency.

 finj

Vd


5 Hz

10 Hz

20 Hz

50 Hz

100 Hz

0V
5V
10 V
15 V

92.2%
92.4%
85.4%
-

88.1%
87.2%
79.1%
-

76.4%
81.8%
73.3%
-

66.7%
74.1%
63.4%
-

60.9%
69.8%
64.2%
53.5%

Fig. 1. Waveforms of the output pulsed beam obtained at
diﬀerent Vd .

ions were locally accumulated in the vicinity of theexit, and as a result, it is possible to extract as a narrow pulse beam.
In the measurement, the electric ﬁeld gradient was
set to be linear. The potential diﬀerence between theentrance and the exit, Vd , and the injection frequencyof the pre-pulsed beam, finj , were used as measurement
parameters. The conversion eﬃciency was greatly improved by the present modiﬁcation. Table 1 shows theconversion eﬃciency with each measurement parameter. Figure 1 shows the waveform of the extracted
pulsed beam when the pre-pulsed beam is injected at
100 Hz, with an ejection cycle of 0.5 Hz. As can beseen in Fig. 1, the pulse width narrows as Vd increases,
and the FWHM is reduced to 418.5 µs at Vd = 15 V.
At the same time, however, the conversion eﬃciency
is relatively small. Methods to solve this problems are
currently under development.
References
1) M. Wakasugi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 668 (2013).
2) K. Tsukada et al., Phys. Rev. Lett. 118, 262501 (2017).
3) T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B
317, 357 (2013).
4) M. Wakasugi et al., Rev. Sci. Instrum. 89, 095107(2018).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Precise magnetic field measurement of WiSES

WiSES1) (Window-frame Spectrometer for Electron
Scattering) is an electron spectrometer for the SCRIT(Self-Conﬁning RI Ion Target) experiment.2,3) The
dipole magnet4) of WISES has a large aperture for themeasurement of scattered electrons in a wide scattering
angle at once. The gap volume of the magnet is 140 cm(width), 29 cm (height), 170 cm (depth). In elastic electron scattering experiments, a typical momentum resolution of δp/p ∼ 10−3 for 150–300 MeV electron energy
is required to separate elastic and inelastic scattering
events. The momentum resolution measured by elastic
scattering for 12 C and 208 Pb is found to not reach thedesign value. To improve further momentum resolution,
we will measure the precise 3D magnetic ﬁelds of the
WiSES magnet with a precision of δB/B ∼ 10−3 .
We will use three Hole probes to measure Bx , By ,and Bz at the same time. The Hall probe has a Hallsensor inside and reacts to the component of the magnetic ﬁeld with respect to the normal direction of thesensor surface. However, the Hall probe also detects themagnetic ﬁeld with respect to the tangent of the sensor,
namely the Planar Hall eﬀect.5) Bprobe detected by theHall probe is expressed as follows:
Bprobe = B cos θ + pH (B sin θ)2 sin 2ϕ,(1)

where θ is the angle between the normal direction of thesensor and the magnetic ﬁeld, and ϕ is the rotation angleof the sensor. The ﬁrst term in Eq. (1) is the Hall eﬀect.
The second term in Eq. (1) corresponds to the Planar
Hall eﬀect. To determine the value of the Planar Hall
coeﬃcient pH of the second term, we measured the 2ϕdependence of each probe in a uniform magnetic ﬁeld.

spacerBiaxial rotary table

∗3

0.002
0
-0.002-0.004
0

100

200

300

400

500

600

[deg]

Fig. 2. Result of 2ϕ dependent magnetic ﬁeld by the Planar
Hall eﬀect. Each color corresponds to the ﬁtting for eachprobe.

The setup is shown in Fig. 1. The probe was mounted
on a rotating stage in the homogeneous ﬁeld region of
the WiSES magnet. The absolute value of the ﬁeld wasmeasured by NMR, which was also located in the homogeneous region. The stage could rotate around twoaxes corresponding to θ and ϕ of Eq. (1), with resolutions of 0.3 mrad. In this measurement, θ was set to be90◦ to suppress the inﬂuence of the ﬁrst term of Eq. (1).
The results for the three probes are shown in Fig. 2.
By adding some mis-alignment angles of our system asﬁtting parameters into Eq. (1), our data are well reproduced. In the present ﬁtting, the followings points areincluded:(a) the contribution from the ﬁrst term of Eq. (1) owing to a small deviation from the 90◦ ,(b) the angle between the probe and the rotary axisof the stage, etc.

References

Fig. 1. Setup of Planar Hall eﬀect measurement in WiSES.
RIKEN Nishina Center
ELPH, Tohoku University
Department of Rikkyo University

0.004

Consequently, the pH s are evaluated to be 0.008, 0.01,
and 0.015. These values are consistent with a previous
study (pH = 0.0148).6) NMR values for each probe areshown in Fig. 2. Although, the evaluation of systematic
errors are ongoing. We will mount three probes on asystem to make a triaxial probe, and create a precise
map of the magnetic ﬁeld of the WiSES magnet at thenext stage.

Hall sensor∗2

NMR value = 0.411 [ T ]NMR value = 0.408 [ T ]NMR value = 0.408 [ T ]

0.006

B

Hall probe

∗1

B[T]

H. Wauke,∗1,∗2 A. Enokizono,∗1 Y. Honda,∗1,∗2 K. Kasama,∗1,∗2 T. Ohnishi,∗1 T. Suda,∗1,∗2 S. Takayama,∗1,∗2
T. Tamae,∗1,∗2 K. Tsukada,∗1,∗2 M. Wakasugi,∗1 and M. Watanabe∗11) 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. 45, 184 (2013).
4) T. Tamae et al., RIKEN Accel. Prog. Rep. 47, 196 (2014).
5) C. Goldberg, R. E. Davis, Phys. Rev. 94, 1121 (1954).
6) S. Tomita, Master Thesis, Tohoku Univ., (2017).

- 145 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

MPV – Parallel Readout Extension of VME
H. Baba,∗1 T. Ichihara,∗1 T. Isobe,∗1 T. Ohnishi,∗1 K. Yoshida,∗1 Y. Watanabe,∗1 S. Ota,∗2 S. Shimoura,∗2 andS. Takeuchi∗2
We have been developing a data acquisition (DAQ)
system at RIBF. The parallel readout VME DAQ system1) was successfully operated in 2016. In this system,
the data readout of all VME modules were completely
parallelized by a mountable controller (MOCO).2) The
DAQ performance was signiﬁcantly improved; however,the usability and robustness of the system was rather
problematic. To solve these problems, we developed
a new MPV system (MOCO with parallelized VME),
which is a type of parallel readout extension of the VME.
When we set up the MOCO system, several unwantedfeatures were found: 1) MOCO was installed between
the VME module and VME backplane; consequently,
the VME module protruded from the VME shelf by
7 cm. Some circuit components on the VME module
were exposed, which caused a short-circuit. 2) MOCO
had USB connectivity. A single PC can handle multiple
MOCOs. However, owing to the congestion in the USB,the data transfer speed fatally degrades. To obtain agood performance, same number of PCs and MOCOs
should be installed. 3) To synchronize events between
MOCOs and other DAQ devices, trigger and busy signals have to be exchanged. For this purpose, four additional pairs of diﬀerential cables were connected to the
MOCO located inside the VME shelf, which creates amess of cables.
In this study, we developed circuit boards known
as the MPV controller (Fig. 1) and MPV backplane(Fig. 2). All DAQ communications (e.g. trigger anddata) for MOCO are done through this controller. Avnet
PicoZed 70103) (red board in Fig. 1), which contains
Xilinx Zynq-7000 All Programmable System-on-Chip, is
adopted as the main circuit of the controller. Logic cirLVDS I/O (4 x 6 Lines)
MOCO 1
MOCO 2
MOCO 3
MOCO 4
MOCO 5
MOCO 6NIM I/O
Trigger,Busy, etc

Avnet PicoZed 7010 isadopted to implement

1Gbps
Ethernet

Data and commands
are communicatedlines routed on the
MPV backplane

Fig. 1. Image of MPV controller. This controller can simultaneously handle up to 6 modules of MOCO.
∗1∗2

RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo

Front side

Rear side
MOCO isinstalledfrom therear side

MPV
Controllerlines are routed
to each slot
J2 C01-C08 pins are
assigned forPower connectors(+5 V, +12 V, -12 V)

Fig. 2. Image of the MPV backplane (5-slot). 7-slot typeis also available. Dimension and mounting holes arecompatible with Schroﬀ/NVENT Monolithic Backplane(23001-065 for 5 slot, 23001-067 for 7 slot).

cuits to handle the MOCO are implemented on PicoZed.
The MPV controller accesses the MOCO through thediﬀerential lines on the backplane. Four pairs of differential lines (LVDS) are routed to each slot from thecontroller position, i.e., there are 24 pairs of diﬀerential
lines on the MPV backplane. In the previous MOCObased system, additional cables and PCs were required.
However, this MPV system does not require any extra
cables and devices. As shown in Fig. 2, the MPV controller is installed at the left-most slot of the backplane.
VME modules are installed at the front, similar to thestandard VME system. Simultaneously, MOCOs are inserted from the rear side of the backplane. A MOCO canaccess the VME module through the DIN41612 connectors. In the standard VME backplane, all slots shared
the VME bus lines. In contrast, the MPV backplane
has an isolated architecture except for power lines. Data
are independently acquired by FPGA on the controller,
which can be read-out from the 1 Gbps ethernet port.
The maximum possible data rate for the six MOCOs
is 960 Mbps, which is within the range of theoreticalthroughput of 1 Gbps ethernet with a jumbo frame.
These features enable the complete parallel read-out of
the VME-based DAQ system.
In conclusion, the hardware of the MPV has been successfully produced. The ﬁrmware for the MPV controller
is under development. This system will be ready in 2019.
References

1) H. Baba et al., RIKEN Accel. Prog. Rep. 50, 224 (2017).
2) H. Baba et al., RIKEN Accel. Prog. Rep. 45, 9 (2012).
3) http://zedboard.org/product/picozed- 146 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Validation method to merge digital data acquisition with analog
data-acquisition system in SAMURAI30 experiment
J. Gao,∗1,∗3 L. Stuhl,∗2 M. Sasano,∗1 K. Yako,∗2 H. Baba,∗1 SAMURAI 30 Experiment Collaboration
In this paper, the method to combine the digital
data acquisition system (DDAQ) of our low-energy
neutron detector PANDORA1) and the analog datacquisition system (DAQ) of standard detectors of
SAMURAI spectrometer2) during the SAMURAI30
experiment3,4) is reported.
PANDORA was optimized to detect neutrons with akinetic energy of 0.1–5 MeV by measuring the related
Time-of-Flight (ToF) in the range of 50–300 ns. Data
from PANDORA bars (each with a signal from bothends) were read out with duplicated readout. CAEN
V1730 modules were used for the charge and pulse
shape discrimination information while an analog circuit (discriminators and CAEN V1290 TDC modules)
was used for timing and triggering.
For the DDAQ, we daisy chained six CAEN V1730B(16-channel modules) and one CAEN V1730D (8channel module) waveform digitizers using an optical connection. The unpublished software of digiTES
based on Digital Pulse Processing for the Pulse ShapeDiscrimination (DPP-PSD) ﬁrmware5) was used to
manage diﬀerent modules in the daisy chain conditionand control the digitizers. A LUPO (Logic Unit for
Programmable Operation) module6,7) was used to generate a 62.5 MHz signal to synchronize timestamps ofthe seven modules and share the clock with another
LUPO in the DAQ system.

The acquisition in the digitizers was not based on
the self-triggering of each channel. The local triggering
option of the two-two coupled channels (in V1730, twoneighboring channels were paired) was used to ensure
the coincidence between photomultipliers of both sidesof PANDORA. The digitizers were conﬁgured to ensure that the validation of the local triggers came froman external trigger based on the costumer conﬁgured
software criteria. To manage the coincidence requirements between the two separate acquisition systems,
the ﬁrst channel (ch 0) of each digitizer was dedicatedto a logic signal. This external trigger validated the
PANDORA self-triggers in a time window of approximately 1 µs.
The validation signal originated from the accepted
trigger of analog DAQ based on the triple coincidence of “BEAM” (from SBT detectors), analog “PANDORA” (recoil neutron) and “HODOSCOPE” (reaction residues at hodoscopes). This typical trigger rate
was 1.3 × 103 Hz.
Consistent with our expectation, six diﬀerent values
were observed in Fig. 1. In comparison with the typicaldead time of SAMURAI DAQ (approximately 100 µs),
this method is enough for us to align the two data sets.
We express our gratitude to the RIKEN and CNS
staﬀ for the stable operation of the accelerators during
the measurement. This work is funded by the China
Scholarship Council, KAKENHI project 16H06716,
the Japan Society for the Promotion of Science, andKurata Grant from the Kurata Memorial Hitachi Science and Technology Foundation.
References

1) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A
866, 164 (2017).
2) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
3) M. Sasano et al., in this report.
4) L. Stuhl et al., in this report.
5) http://www.caen.it/csite/CaenProd.jsp .
6) https://ribf.riken.jp/RIBFDAQ/index.php?DAQ .
7) H. Baba et al., Nucl. Instrum. Methods Phys. Res. A
777, 75 (2015).

count

4e+05

2e+05

0e+00
100

105

110

(TSdigitizer − TSlupo) ns

115

Fig. 1. Time stamp diﬀerence between DDAQ and DAQ.
V1730B/D has 2 ns timestamp resolution while LUPO
has 10 ns resolurion.
∗1
∗2
∗3

RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo
School of Physics, Peking University- 147 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Development of 1.5-mm thick liquid hydrogen target

We report on the development of a thin liquid hydrogen target using the CRYPTA system.1) We aim to
perform missing mass experiments on proton-rich nuclei with high statistics and reasonable resolution via
one and two neutron transfer ((p, d) and (p, t), respectively) reactions with 50 MeV/nucleon radioactive
beams, which generate deuterons and tritons ranging
between 10 and 30 MeV/nucleon. Consequently we obtained a 1.5 mm thick liquid hydrogen target.
The system was placed in a vacuum chamber. A target cell was connected to a refrigerator with a copper
bar and cooled down below the boiling point. To monitor the temperatures, a thermometer labeled ‘A’ wasattached to the connecting end of the cell and ‘B’ wasattached to the surface of the window frame, as shownin Fig. 1 (a). A gas pipe was connected to the inside of
the cell. The pipe was also connected to a reserver tankplaced outside the vacuum chamber, which was filledwith hydrogen gas. Hydrogen was introduced from thetank to the cell. The hydrogen gas was liquefied nearthermometer A and dropped into the cell. A heater wasplaced near thermometer A to maintain the temperature
above the melting point.
The target cell consisted of one body frame and two
window frames, all made of aluminum, as shown in
Fig. 1 (b). Each window frame had a hole with a diameter of 20-mm at the center. The window frame ofthe downstream side was tapered to detect recoil particles at large angles. The side view of the constructed
target cell is shown in Fig. 1 (a). The volume was defined by a pair of 6.47-µm-thick HAVER foils glued to
the window frames. The designed distance between the
(a)

(b)

A (T1 )

B (T2 )

7 mm

Beam

20 mm

20 mm

1.5 mmFig. 1. (a) Side view of the cross-section of target cell. Blue
area is filled with liquid hydrogen. Green squares indicate
the thermometers. (b) Side view of the cross-section oftarget cell components.
∗1∗2

Department of Physics, University of Tokyo
RIKEN Nishina Center

Temperature (K)S. Koyama∗1,∗2 and D. Suzuki∗2
22
21

thermometer A (T )20thermometer B (T )

1
2

19
18
17
16
15
14

R1

13
12

−5

R2
0

R3

R4

5

10

15

20

Time (min)Fig. 2. Variation of temperatures during liquefaction.

foils was 0.5 mm. The liquid hydrogen volume thus defined expanded toward the outside by 0.5 mm at thecenter of each side due to the 0.8-atm gas pressure. The
shape of the expansion was measured with a laser displacement sensor. The total thickness was found to be
1.5 mm at the center. We had no experience of liquefaction of hydrogen in such narrow volume and tested todetermine the design of the window frames. Finally, weplaced a 7-mm thick volume outside the foils to fully fill
the target cell, as shown in Fig. 1 (a).
We performed a test at our test-bench at the RIBF. To
visually confirm that the target cell was fully filled withliquid hydrogen, one of the foils was replaced with a 125µm-thick Kapton foil. Figure 2 shows the variations in
the temperature of thermometer A (T1 ) and thermometer B (T2 ) during liquefaction. Before introducing thehydrogen gas, the target system was maintained at temperatures above the melting point by the heater (R1 ).
When hydrogen gas was gradually introduced, the temperature of the target became higher because hydrogengas was cooled (R2 ). Liquefaction gradually occurred
while the temperature was almost constant (R3 ). During this step, it was observed from outside that only
the lower part of the 20-mm diameter hole was filled.
While the cell was filled only partially, the full 7-mm
thick volume was likely filled at this point. Then, thetemperature started to decrease (R4 ). When T1 became
lower than 15.5 K, the heater turned on and the rate ofdecrease reduced. T1 suddenly increased at t = 9.5 min,as indicated by the red arrow. At this point the target
was fully filled. This behavior of temperature was observed using HAVAR foils at both sides. Therefore, we
consider the target was also fully filled in this condition.
Reference

1) H. Ryuto et al., Nucl. Instrum. Methods Phys. Res. A
555, 1 (2005).

- 148 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Profile measurement of a large target cell of liquid hydrogen
M. Miwa,∗1,∗2 M. Sasano,∗2 X. Sun,∗3,∗2 L. Stuhl,∗4 J. Gao,∗3,∗2 and M. Kurata-Nishimura∗2
The (p, n) reaction in inverse kinematics is a powerful probe for studying nuclear isovector responses in
unstable nuclei. In May 2018, the SAMURAI 30 experiment was performed using PANDORA1) and SAMURAI2) setup with a liquid hydrogen target3) to study
the GT transitions ,including their resonances, in the11
Li and 14 Be neutron drip line nuclei.4,5)
In general, the target thickness along the beam direction is required to obtain the cross sections. However, inthe case of a liquid hydrogen target that contains withthin membranes, the target thickness strongly depends
on the inﬂation of the membranes due to the diﬀerential
pressure between liquid hydrogen and the vacuum in thetarget chamber.
In the SAMURAI 30 experiment, the target cell was
tilted at 45◦ with respect to the beam direction, sothat the recoil neutrons of interest, which were emitted
around 90◦ , did not penetrate the target frame structures. Because the inﬂated target cell was tilted withrespect to the beam line, the evaluation of the target
thickness required three-dimensional analysis of the target shape. In this work, we measured the proﬁle of alarge target cell of liquid hydrogen by using a laser displacement meter and obtained the eﬀective target thickness along the beam direction by analyzing the proﬁledata.
Figure 1 schematically shows the setup for the target
proﬁle measurement. The target cell was ﬁlled with N2
gas, instead of liquid H2 , at 1719 Pa, which corresponds

Fig. 1. Schematic of the setup for the two-dimensional profile measurement of the target thickness. The membranesof both sides are irradiated with a laser in the beam direction.
∗1
∗2
∗3
∗4

Department of Physics, Saitama University
RIKEN Nishina Center
School of Physics, Peking University
Center for Nuclear Study, University of Tokyo

Fig. 2. Profile result of the target shape. The vertical axis
indicates the spatial coordinate along the beam direction.
The blue and red plots are the original data after thecalibration and the data at an angle of 45◦ respectively.

to the diﬀerential pressure of 0.72 kPa. A laser displacement meter (KEYENCE LJ-G5000) was used to measure the target proﬁle. The laser vertically irradiatedthe target cell surface. The conﬁguration of the laser intensity was automatic, and the sampling time was 2 ms.
The measurement can decide the absolute value only inthe beam direction, while the position information in thehorizontal direction can be just obtained as relative values. The scale of the horizontal position was calibrated
by adjusting the inner diameter of the target frame to be
the designed value, 50 mm. Here, we note that a typicalbeam spot of an RI beam at the SAMURAI F13 focal
plane has a width of ±10 mm and a height of ±20 mm.
As a result of the proﬁle measurement, we obtained
the target shape data shown in Fig. 2. The blue plots
represent original data while the red plots are tilted at
an angle of 45◦ . The proﬁle analysis provided the target thickness after 45-degree rotation as 15.8 mm at thecenter, 14.3 mm at x = ±10 mm, and 7.40 mm at y =±20 mm.
In summary, we evaluated the target proﬁle in the
SAMURAI 30 experiment, taking into account the target tilting with respect to the beam direction throughthe three-dimensional analysis of the target cell.
References

1) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A 866,
164 (2017).
2) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 304 (2013).
3) H. Ryuto et al., Nucl. Instrum. Methods Phys. Res. A
555, 1 (2005).
4) L. Stuhl et al., in this report.
5) J. Gao et al., in this report.

- 149 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

The stability of the liquid hydrogen target system during the
SAMURAI 30 experiment
X. Sun,∗1,∗2 M. Sasano,∗2 M. Miwa,∗3,∗2 L. Stuhl,∗4 and J. Gao∗1,∗2
The charge-exchange (p, n) reactions in inverse kinematics are powerful tools to study the spin-isospin response of light nuclei. In general, Polyethylene (CH2 )is used as the hydrogen target to induce the (p, n) reactions, because it is easy to handle and has uniform
thickness. However, the background generated fromthe carbon in CH2 is serious.
In the SAMURAI 30 experiment, a thick liquid hydrogen target (LHT)1) was used to perform the measurements of the (p, n) reactions with a high reaction
rate and lower background from carbon. It was required to keep the temperature of the target cell below the boiling point of hydrogen during the measurement. In this report, the stability of the temperatureand pressure of the LHT system during the SAMURAI
30 beam time is reported.
The setup of the LHT system is described in Ref. 1).
A Giﬀord-McMahon cycle (GM) refrigerator was used
to keep the target cell at a low temperature in order
to liquefy the hydrogen. A heat shield covered by aluminum foil was installed around the target cell to prevent heat inﬂow from the room temperature environment. A Cu tube was used to connect the target cellto the GM refrigerator, to which a heater was attached
to control the temperature.
The temperatures of the target cell and the Cu tube
were measured using a Si diode thermometer. In the
SAMURAI 30 experiment, hydrogen gas with a pressure of 812 hPa was ﬁlled into the cell after cooling
down the system. The pressure decreased to around
500 hPa when the hydrogen gas was liqueﬁed. Under such conditions, the temperature of the target cellshould be kept lower than 18 K during the measurement in order to keep the hydrogen in liquid form.
Figure 1 shows the variations of the temperature andgas pressure with time after the hydrogen gas was liqueﬁed. The temperature was found to be instable during the ﬁrst 8 hours. The temperatures of the target
cell and the Cu tube increased steadily. In order tolower the temperature, the temperature of the waterin the chiller was decreased from 22◦ C to 8◦ C. However, it was found that this operation had almost no
inﬂuence on the temperature of the LHT system. The
temperature increased gradually, as shown in Fig. 1,
but the liquid phase was maintained at just below theboiling point. The temperature of the target cell stabilized at 18.3 K after the pressure of the hydrogen
∗1
∗2
∗3
∗4

Fig. 1. Variations of the temperature (top panel) and gas
pressure (bottom panel) with time. The temperature
was measured for both the target cell (blue line) andthe Cu connector (red line).

was added to 710 hPa. However, for some reason, a
rapid decrease in temperature and pressure was observed 4 hours later. When the temperature of the Cu
tube decreased to 14.7 K, the heater started working.
The temperature of the target cell was kept at about
15 K and the gas pressure was stable at 705 hPa. The
LHT system was maintained at a stable temperatureand pressure for more than 8 hours.
In summary, in the SAMURAI 30 experiment, theinstability of the LHT system was observed during theﬁrst 8 hours of the beam time. During the rest of
the beam time, the ﬂuctuation of the temperature andpressure of the LHT system were less than 1.5% and
1%, respectively. Further investigation is necessary toachieve stable control of the system temperature andpressure for a long time.
Reference

School of Physics, Peking University
RIKEN Nishina Center
Department of Physics, Saitama University
Center for Nuclear Study, University of Tokyo

1) H. Ryuto et al., Nucl. Instrum. Methods Phys. Res. A
555, 1 (2005).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Design of an Ion Source for the eSHE project
Toward Pioneering Electron Scattering on Superheavy Elements
S. Naimi,∗1 T. K. Sato,∗2 K. Tsukada,∗3 P. Schury,∗4 Y. Ito,∗3 H. Haba,∗1 Y. Komori,∗1 T. Ohnishi,∗1
and T. Uesaka∗1
Theoretical study shows that the central depression
in the nucleonic density is enhanced in superheavy nuclei and is correlated with the symmetry energy.1) Electron scattering is a very reliable technique to probe thecharge density in heavy nuclei.
The electron scattering on SuperHeavy Elements
project, or eSHE project for short, aims at pioneering
electron scattering on heavy and superheavy nuclei bycreating a missing link between two powerful facilities
at RIKEN, the AVF cyclotron and the SCRIT facility.
The AVF facility can produce heavy and superheavy
nuclei. The SCRIT facility is dedicated for electron
scattering on Rare Isotopes (RIs).2) The eSHE project
mission consists in bringing RIs produced at AVF to
the SCRIT facility to perform electron scattering. For
this purpose, we prepare a target from RIs produced at
AVF, which is then transport to SCRIT facility where
the target could be inserted into the oven of ion source
designed for this purpose. Since the preparation andtransport of the target will take time, only RIs with long
lifetime (at least few hours) are considered. Figure 1
shows nuclei heavier than 208 Pb that could be reachedby this method. However, the feasibility of SHEs will
be limited by the production yield even for long-lived
nuclei and a more eﬃcient method is needed. To test
the feasibility of this method, we plan to conduct a pilot
experiment with 225 Ac with a half-life of 10 days. This
isotope can be produced with high intensity at AVF
via the reaction 226 Ra(d, 3n)225 Ac, with 24 MeV and10 μA deuterium beam. To perform electron scatteringexperiment for 10 hours, a target of 0.3–3 GBq 225 Ac isneeded. Due to the low ionisation potential of Ac element, it is possible to achieve high ionisation eﬃciency
with a surface ion source type.3) Design of such ion
source is shown in Fig. 2, where a double valve system
is used to allow insertion of RIs target into the oven of
the ion source without breaking the vacuum. The ion
source is now under construction and it will be commissioned ﬁrstly oﬄine with Lanthanum, which is available
commercially as La2 O3 powder. The online commissioning will be performed with 225 Ac produced at the
AVF. The aim is to estimate the total eﬃciency and production, which will determine the feasibility of electron
scattering at SCRIT. To achieve the necessary accuracy
for electron scattering study, a beam of 106 − 107 ions
per second is needed for a period of one month.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Research group for Heavy Element Nuclear Science, JAEA
Research Center for Electron Photon Science, Tohoku University
WNSC, IPNS, KEK

Known
w heavy and Superheavy nuclei
Protons
Neutrons

NihoniumHalf-life

208Pb

<1s
seconds
minutes
hours
days
years
Gyear
>Gy

Nuclei available for the eSHE project

208Pb

Pilot experimentwith 225Ac

Fig. 1. (Top) All known nuclei heavier than 208 Pb isotope(Bottom) Nuclei with long enough lifetimes that would
be available for the eSHE project. A pilot experimentwill be conducted with 225 Ac.

Movable holder to allow
target insertion
ValvesOven

Ionizer

Target+MovableholderHigh-vacuum+

Double valve
systemFig. 2. Design of an ion source for Ac ionization. In thelower left side is shown the schematic of insertion of RIs
target into the oven without breaking the vacuum.

References

1) B. Schuetrumpf et al., Phys. Rev. C 96 (2017).
2) K. Tsukada et al., Phys. Rev. Lett. 118 (2017).
3) T. K. Sato et al., Nature 520 (2015).

- 151 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Absolute optical absorption cross-section of Rb atoms injected into
superfluid helium using energetic ion beams†
K. Imamura,∗1,∗2 Y. Matsuo,∗2,∗3 W. Kobayashi,∗2,∗3 T. Egami,∗2,∗3 M. Sanjo,∗2,∗3 A. Takamine,∗2 T. Fujita,∗2,∗4
D. Tominaga,∗2,∗3 Y. Nakamura,∗1,∗2 T. Furukawa,∗5 T. Wakui,∗6 Y. Ichikawa,∗2 H. Nishibata,∗2 T. Sato,∗2
A. Gladokov,∗2,∗6 L. C. Tao,∗2,∗8 T. Kawaguchi,∗2,∗3 Y. Baba,∗3 M. Iijima,∗3 H. Gonda,∗3 Y. Takeuchi,∗3
R. Nakazato,∗3 H. Odashima,∗1 and H. Ueno∗2
An in-situ laser spectroscopy method utilizing atomic
impurity in superﬂuid helium (He II) has been developed
for the application of nuclear structure study of rareisotopes. The method is named Optical RI-atom Observation in Condensed Helium as Ion-catcher (OROCHI).
The key feature of the technique is that the center wavelengths of the absorption spectra of atoms in He II arelargely blue-sifted from those of emission spectra. The
feature is signiﬁcantly advantageous for the detectionof ﬂuorescence signals from atoms in He II with ultralow background. Moreover, He II works as an eﬀective
stopper for highly energetic ion beams. The stopping
eﬃciency of He II reaches nearly 100% for the beam energy of several tens of MeV/nucleon. Considering theabove reasons, OROCHI has proven to be an eﬃcientmethod for the study of nuclear structure of low production yield rare-isotopes. We have demonstrated thefeasibility of OROCHI using 84–87 Rb ion beams with up
to 66 MeV/nucleon energy and 104 pps intensity, so far.1)
However, unexpected laser stray light limits the signal
detection sensitivity. To eﬃciently separate the signal
from background, we developed a new ﬂuorescence detection system (FDS) that realizes low background signal detection using double monochromator. The ﬁrst
demonstration of the new FDS was performed using
85
Rb31+ ion beam delivered from RIPS. We deduced theoptical absorption cross-section from the result of ﬂuorescence intensity dependence on beam intensity andapplied laser power.
The experimental setup was the same as that inRef. 2). A 66 MeV/nucleon 85 Rb ion beam was passed
through two aluminum energy degraders to adjust the
stopping position in He II. During beam stopping position adjustment using various degraders thickness, we
conﬁrmed that the injected ions were stopped within
1 mm injection depth. The energy degraded ion beam
was introduced into He II. Rubidiums that were diﬀusedfrom the observation region with approximately several
hundred miliseconds after stopping in He II were subjected to a laser light from the Titanium sapphire laser(780 nm, ϕ ≈ 2 mm). The laser induced ﬂuorescence(LIF) from Rb atoms was focused on the optical ﬁber
†

∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

Condensed from the article in Appl. Phys. Exp. 12, 016502 (2019)
Department of Physics, Meiji University
RIKEN Nishina Center
Department of Advanced Sciences, Hosei University
Department of Physics, Osaka University
Department of Physics, Tokyo Metropolitan University
National Institute for Radiological Science
Department of Physics, Kyungpook National University
School of Physics, Peking University

Fig. 1. Measured fluorescence intensity dependence normalized by injected beam intensity.

bundle with an entrance of 5 × 2 mm2 using the lensunit of the FDS. The LIF guided using the optical ﬁber
bundle was introduced into the double monochromator.
Rb D1 emission light (793 nm in He II) was selectedusing the double monochromator and detected using aphoto-multiplier tube.
The measured LIF dependence on beam intensity andapplied laser power is shown in Fig. 1. The verticalaxis was normalized by the beam intensity and the horizontal axis shows the applied laser power. The observed LIF intensity ILIF was obtained using the equation ILIF = Nobs σ ΦLaser ϵdet , where Nobs , σ, ΦLaser andϵdet , denote the number of atoms in the observation region, optical absorption cross-section, photon ﬂux of thelaser, and detection eﬃciency of FDS, respectively. Nobs
was estimated from the beam intensity Ibeam and diﬀusion time of Rb atom. ΦLaser was proportional to theapplied laser power PLaser . Thus, the equation for normalized LIF intensity ILIF /Ibeam can be written as afunction of PLaser . The value of ϵdet ≈ 10−7 obtained
from the result of experiment using Rb enclosed gas cell
was used for the deduction of σ. As a result of ouranalysis, we deduced σ = 3.59(16) × 10−15 cm2 as the
optical absorption cross-section of Rb in He II. The successful derivation of the quantitative value attributes tothe improvement of detection eﬃciency by two orders ofmagnitude using the new FDS, as compared to previous work.1) We conclude that 200 pps is a suﬃcient ion
beam intensity to detect LIF from Rb atoms in He II inaccordance with our experimental result.
References

1) X. F. Yang et al., Phys. Rev. A 90, 052516 (2014).
2) K. Imamura et al., RIKEN Accel. Prog. Rep. 50, 197 (2017).

- 152 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)Baseline correction system of laser-microwave double resonancespectrum for atoms injected into superfluid helium by laser sputtering
M. Sanjo,∗1,∗2 K. Imamura,∗2,∗3 W. Kobayashi,∗1,∗2 Y. Takeuchi,∗1,∗2 A. Takamine,∗2 T. Furukawa,∗2,∗4
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) tomeasure the hyperﬁne structure and Zeeman splitting of
unstable nuclei with low production yields and short lifetimes. In this method, highly energetic ion beams are efﬁciently caught as neutralized atoms in superﬂuid helium
owing to its high density. In addition, the absorption
wavelength of atoms in He II is largely blue-shifted dueto the eﬀect of surrounding He atoms while the emission
wavelength is almost the same as that in vacuum. This
enables us to detect photons emitted from the atoms withlow background by removing the excitation-laser straylight.
So far, in the oﬄine experiment, we succeeded in
the measurement of the hyperﬁne structure constant for133
Cs atoms with accuracy of 10−5 via laser-microwave(MW) double resonance method.1) In order to discuss
hyperﬁne anomaly of atoms in He II, it is required tomeasure hyperﬁne structure splitting using more than
two isotopes. To show the feasibility for deducing hyperﬁne anomaly parameter using the method, we have
performed a series of experiment to measure hyperﬁnesplitting with an accuracy and a precision of 10−6 using
Rb which has two stable isotopes. It has been diﬃcult
to realize suﬃcient measurement accuracy and precision
due to ﬂuctuation of the number of observed photons
when we use two-step laser sputtering method to supply
atoms in He II.2) We here report the development of abaseline correction system to cancel the ﬂuctuation of thenumber of atoms injected into He II and a preliminary
experiment performed using this system.
We need to irradiate a circularly polarized laser lightand apply a magnetic ﬁeld to the atoms to generate spinpolarization. We can observe ﬂuorescence from atoms
when MW frequency is resonant to the hyperﬁne structure splitting by scanning MW frequency irradiated tospin polarized atoms. On the other hand, when the excitation laser light is linearly polarized light, we observe
photons proportional to the number of atoms in the observation region, because spin polarization does not occur. We can correct the ﬂuctuation of the number ofobserved photons by using the diﬀerence in the observed
photons for both polarizations.
The correction system consists of an Electrooptic
Modulator (EOM) to quickly switch the polarization of
the excitation-laser and a Multi Channel Scaler (MCS)
equipped with multi-channel inputs to count photons at
the circularly and linearly polarization. In the case that
we apply a square wave voltage at 1 kHz to the EOM,
∗1
∗2
∗3
∗4

Department of Advanced Science, Hosei University
RIKEN Nishina Center
RIIS, Okayama University
Department of Physics, Toho University

Fig. 1. (a) Scheme of observed photon number calibration via
switching of the polarization of excitation-laser with an
EOM. (b) Cancellation of the fluctuation of the numberof observed photons using Rb in He II.

the polarization is switched as shown in the upper ofFig. 1(a). Next, we detect photons emitted from theatoms at the circularly polarized section (ch. 1) and thelinearly polarized section (ch. 2) alternately using coincidence with the signal to EOM as shown in the lower ofFig. 1(a). In ch. 1, hyperﬁne structure resonance peaksuperimposed with the base ﬂuctuation caused by the
number of atoms variation is observed. In ch. 2, photons proportional to the number of atoms in the observation region is observed. Consequently, it is expectedthat we can realize measurement free from the ﬂuctuation of number of observed photons by correcting ch. 1
signal counts with ch. 2 ones.
We performed a preliminary experiment for Rb atoms
injected into He II by laser sputtering. Atoms are irradiated with a Ti:Sa laser of 100 mW (wavelength: 780 nm)
either with circular or linear polarization. Fig. 1(b)shows the spectrum obtained when we swept the magnetic ﬁeld. We attempted to observe the ﬂuorescence
twin peaks when the spin polarization is collapsed at the
0 magnetic ﬁeld. Channel 1 (white line) in the upper
part of Fig. 1(b) shows spectrum in the circularly polarized section, and ch. 2 (red line) shows the spectrum inthe linearly polarized section. The lower part of Fig. 1(b)shows the number-of-atoms corrected spectrum. It was
conﬁrmed that the baseline ﬂuctuation is clearly canceled. From the result, we concluded that we succeededin the baseline correction. Future outlook on researchis the measurement of hyperﬁne structure for 85, 87 Rb
in He II with using this system to evaluate hyperﬁneanomaly for Rb isotopes in He II.
References

1) K. Imamura, et al., Hyperfine Intaract. 230, 73 (2015).
2) T. Furukawa, Phys. Rev. Lett. 96, 095301 (2006).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Attempt to measure relaxation time of atomic bubble surrounding
alkaline atoms in superfluid helium
Y. Takeuchi,∗1,∗2 M. Sanjo,∗1,∗2 W. Kobayashi,∗1,∗2 H. Kuramochi,∗3 A. Takamine,∗2 Y. Matsuo,∗1,∗2 Y. Zempo,∗4
T. Tahara,∗3 and H. Ueno∗2
Our research group has been developing a new typeof nuclear laser spectroscopy method named OROCHI,
which is based on laser spectroscopy of atoms in superﬂuid helium (He II). In this method, the presence of theinteraction between injected atoms and surrounding helium atoms plays an important role to prepare a uniquespectroscopic environment. In this study, we focus on
the structure of the atoms surrounded by He.
When the atoms are introduced into He II, the surrounding helium atoms are pushed out by the exchange(Pauli) repulsion force.1) The resulting vacuum region iscalled “atomic bubble.” For the electronic ground stateof the introduced atom, the bubble typically has a radiusof 5 ∼ 10 Å. When the shape of the electron orbit of theatom changes owing to a state transition such as excitation and absorption, it is considered that atomic bubble
is also deformed in He II as the shape of the orbital deforms.
Figure 1 shows the deformation process of the atomic
bubble. Because the Franck-Condon principle holds truein the process of absorbing and releasing photons, the radius of the bubble is kept constant before and after thetransitions. Therefore, after these short time transitions,the bubble is aﬀected by the electron orbit of the introduced atom and deforms (relaxes) over a certain time.
It is known that the wavelengths of atoms in He II shift
between absorption and emission owing to this process.2)
It is estimated that it takes an order of a few pico seconds to deform the bubble but so far the relaxation time
has not been measured in the time domain. To clarify
the dynamics of the atomic bubble system, we will combine the laser spectroscopic technique in He II and theultrafast laser spectroscopic technique.3)
In this research, we decided to start with Rb as the target atom of this experiment because its characteristics in
He II is well studied.2,4) We plan to perform experiments
using a detection system with a high time resolution for
the relaxation time in the excited state.

Fig. 2. Energy calculated value of Rb atomic bubble system.
(18 helium, Hybrid density functional APF with the basis
set Def2TZVPP was used.)

The experiment will be conducted in an oﬄine environment using laser ablation for the introduction of atoms.4)
In the cryostat used for oﬄine experiments, the atoms aresupplied by laser ablation and laser dissociation into He
II in a quartz cell installed in the upper part of the helium
tank. Then, a pumping laser irradiates to Rb atoms in
the observation region and ﬂuorescence is observed using
the Time-Correlated Single Photon Counting (TCSPC)
system. We plan to obtain the time dependence of theintensity of ﬂuorescence using this system that records
the time diﬀerence between the irradiation of the excitation laser signal and the detection of the ﬂuorescentphoton.5) The time resolution of the system is approximately 80 ps. It is considered that emission also occurs
during the deformation process of the bubble to the energy minimum of the excited state. Therefore, if we canobserve the intensity changes of ﬂuorescence up to several
tens of ns, which is the spontaneous emission lifetime, we
can estimate the time required for bubble deformation.
Currently, performance evaluation of picosecond pulsed
Ti: sapphire laser for excitation is ongoing.
Additionally, in parallel with the preparation of the experiment, we calculated atomic energy levels using Gaussian 09 to estimate the amount of wavelength change dueto the relaxation of atomic bubbles. The calculation of
the energy of the atomic bubble formed by 18 helium
atoms resulted in the conﬁrmation of the broadening of
the bubble radius and shifts in the atomic transition energy (Fig. 2). Besides, we will derive the inﬂuence dueto the increase of the number of He atoms for bubble
formation and simulate the case for other atoms such as
Cs.
References

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 Digital Media, Hosei University

1) H. Bauer et al., Phys. Lett. A 146, 134 (1990).
2) Y. Takahashi et al., Phys. Rev. Lett. 71, 1035 (1993).
3) D. Mandal et al., Chem. Phys. Lett. 359, 77 (2002).
4) T. Furukawa et al., Hyperfine Interact 196, 191 (2010).
5) W. Becker, Advanced Time-Correlated Single Photon
Counting Techniques, (Springer, Berlin, Heidelberg, 2005).
- 154 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Development of oﬄine ion source for collinear laser spectroscopy of
RI beams
M. Tajima,∗1 A. Takamine,∗1 T. Asakawa,∗2 M. Wada,∗3 Y. Sasaki,∗2 Y. Nakamura,∗4 H. Iimura,∗5,∗1
K. Okada,∗6 T. Sonoda,∗1 H. A. Schuessler,∗7,∗1 H. Odashima,∗4 Y. Matsuo,∗2,∗1 and H. Ueno∗1
Collinear laser spectroscopy of RI beams is a powerful probe to directly measure the nuclear propertiesof ground or isomeric states. We designed and constructed an oﬄine ion source for the planned optical
spectroscopy of RI ion beams of refractory elements
at a rate of 100 pps. Because it is diﬃcult to obtainions of refractory elements by the widely-used surface
ionization method, we adopted laser ablation of a solid
target in He gas and the RF ion guide system1) for ion
beams with low emittance.
Figure 1(a) shows a sketch of the setup. The RF ion
guide system is composed of cylindrical DC electrodes,
RF carpet (RFCP), a quadrupole ion guide (QPIG),
and RFQ. There are 54 electrodes and an exit holeat the center of RFCP. QPIG is composed of 4 thinplates with 28 electrodes on each plate assembled as
an azimuthally four-segmented square tube. RFQ iscomposed of three segments of four SUS rods and an
endcap. A solid target for laser ablation is ﬁxed on
the surface of the cylindrical electrode. An aluminosilicate Cs+ emitter is also prepared for the performance
test. Helium gas is introduced constantly and the typical pressure is approximately 22 mbar at the most
upstream chamber. This ion source system is ﬂoatedat 10 kV and connected to a test beamline through an
insulation ﬂange as shown in Fig. 1(b).
The target is irradiated by an Nd:YAG laser pulse(532 nm, 10 ns width). First, the produced energetic
ions are stopped via collisions with He gas and guided
to RFCP by a DC electric ﬁeld. Then, the ions are subsequently guided to the downstream by RFCP, QPIG,
and RFQ with applied RF and DC electric ﬁelds. Afterthe ions are focused through the Einzel lens and four
quadrupoles, they are separated depending on m/q using a dipole magnet and collected onto a Faraday cup(FC). Figures 1(c)–(e) show the relative beam intensity as a function of the applied RF amplitudes for
RFCP, QPIG, and RFQ, respectively, when Ag metaltarget was used for laser ablation and the Cs+ emitter
was used as a reference. Typical beam intensity at FC
is 107 –108 ions per laser pulse, which is suﬃcient forthe demonstration of the planned spectroscopy of RI
beams.
∗1

∗2
∗3
∗4
∗5
∗6
∗7

RIKEN Nishina Center
Department of Advanced Sciences, Hosei University
Wako Nuclear Science Center, KEK
Department of Physics, Meiji University
Nuclear Science and Engineering Research Center, JAEA
Department of Physics, Sophia University
Department of Physics and Astronomy, Texas A&M University- 155 -

Fig. 1. Sketch of the ion-source system (a) and test beamline (b). Dependence of beam intensity at the Faraday
cup as a function of applied RF amplitude for RFCP(c), QPIG (d), and RFQ (e).

As the next step, laser ablation for diﬀerent targets such as BaF2 and Zr will be conducted. In addition, we will work toward the development of on-line
spectroscopy for low-intensity beams with coincidence
method.2)
References
1) M. Wada et al., Nucl. Instrum. Methods Phys. Res. B
204, 570 (2003).
2) D. A. Eastham et al., Opt. Commun. 82, 23 (1991).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Development of active nuclear spin maser
with time-separated feedback scheme for Xe-EDM search
T. Sato,∗1 Y. Ichikawa,∗1 A. Takamine,∗1 A. Gladkov,∗1 T. Inoue,∗2,∗3 A. Uchiyama,∗3,∗1 S. Kojima,∗4
C. Funayama,∗4 S. Tanaka,∗4 Y. Sakamoto,∗4 Y. Ohtomo,∗4 C. Hirao,∗4 M. Chikamori,∗4 E. Hikota,∗4 T. Suzuki,∗4
M. Tsuchiya,∗4 T. Furukawa,∗5 A. Yoshimi,∗6,∗1 C. P. Bidinosti,∗7 T. Ino,∗8 H. Ueno,∗1 Y. Matsuo,∗9,∗1
T. Fukuyama,∗10 N. Yoshinaga,∗11 Y. Sakemi,∗12,∗4 and K. Asahi∗1,∗4
CP violation is one of the critical requirements for generating matter-antimatter asymmetry in the Universe.
It is known that the magnitude of CP violation in theStandard Model (SM) of particle physics is insuﬃcient to
explain the observed matter dominance in the Universe,
and therefore the discovery of extra CP violations originating from new physics beyond the SM is much awaited.
A ﬁnite permanent electric dipole moment (EDM) of aparticle or a system implies the violation of time reversal and CP symmetry. The value of EDMs that are
predicted by theories beyond the SM are typically manyorders of magnitude larger than those predicted by theSM, and therefore the EDM is one of the most promisingprobes to search for new physics.
In the current study, we focus on the atomic EDM
of Xe, which is sensitive to T, P-odd nucleon-nucleon
and nucleon-electron interaction. The EDM is detectedby measuring the Larmor frequency of a nuclear spin
under the static magnetic and electric ﬁeld applied at
the same time. In order to improve the upper limit of
the current for the Xe atomic EDM, 4.1 × 10−27 e · cm,1)
which corresponds to a ∼40-nHz frequency precision under a 10-kV/cm electric ﬁeld, we are developing a nuclear
spin maser with an active feedback scheme,2–4) which allows observation of a continuous spin oscillation avoiding
decay of the signal. In addition, to reduce systematic
uncertainties in the spin precession frequency, we aredeveloping co-existing masers of 129 Xe and 131 Xe.5) By
comparing the frequencies of two masers, the systematic
uncertainty, which is caused by drifts in the magnetic
ﬁeld and in the eﬀective ﬁeld due to the Fermi-contact
interaction between Xe and polarized Rb, can be reduced.
We recently found that systematic errors can be further eliminated by reducing the phase deviation between
the observed signal and the actual Xe precession causedby the feedback ﬁeld for masing. The spin precession of
Xe is detected through the motion of Rb spins, which
adiabatically follow the rotating ﬁeld produced by the∗1

RIKEN Nishina Center
FRIS, Tohoku University∗3 CYRIC, Tohoku University∗4 Department of Physics, Tokyo Institute of Technology∗5 Department of Physics, Toho University∗6 RIIS, Okayama University∗7 Department of Physics, University of Winnipeg∗8 Institute of Material Structure Science, KEK∗9 Department of Advanced Sciences, Hosei University∗10 RCNP, Osaka University∗11 Department of Physics, Saitama University∗12 CNS, University of Tokyo∗2

Fig. 1. Maser signals obtained for 129 Xe (left) and 131 Xe(right) with the TSFB scheme. The observation-feedback
cycle is repeated every 40 s. After observation for 30 s
and a margin of 2 s, a 3 s FB signal was applied to maintain the oscillation of the masers (black arrows).

Xe spins. When the feedback ﬁeld is superimposedon the Xe spin ﬁeld, the Rb spin will follow the resultant Xe plus feedback ﬁeld, and hence the Rb precession phase will be shifted from the Xe precession.
The phase shift causes frequency error due to the frequency pulling eﬀect.2) To eliminate the pulling eﬀect,
we adopt a new scheme for masing, the time-separated
feedback (TSFB) scheme. In this scheme, the observation of spin precession and application of the feedback
ﬁeld are separated in time and repeated alternately. The
feedback ﬁeld is generated according to the precession
signal, which is acquired during the period without the
feedback ﬁeld, so that the maser operation becomes freefrom the frequency pulling eﬀect. Note that the spin
precession is observed continuously, unlike the repeatedfree-induction-decay measurements.
A typical signal obtained from the co-existing masersof 129 Xe and 131 Xe with the TSFB scheme is shown in
Fig. 1. The frequency error due to the drift in the powerof the pumping light for Xe polarization was the dominant source of errors in the conventional active maser.
Using the TSFB scheme, we have succeeded in reducing
this error from ∼1.6 µHz to below 60 nHz. A detailed
study on the frequency characteristics and stability of
the TSFB maser is in progress.
References

1) M. A. Rosenberry, T. E. Chupp, Phys. Rev. Lett. 86, 22(2001).
2) A. Yoshimi et al., Phys. Lett. A 304, 13 (2002).
3) A. Yoshimi et al., Phys. Lett. A 376, 1924 (2012).
4) T. Inoue et al., Eur. Phys. J. D 70, 129 (2016).
5) T. Sato et al., Phys. Lett. A 382, 588 (2018).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Epithermal neutron spin filter with dynamic nuclear polarization using
photo-excited triplet electron
S. Takada,∗1,∗2 K. Tateishi,∗1 T. Inoue,∗1 Y. Wakabayashi,∗3 Y. Ikeda,∗3 Y. Otake,∗3 T. Yoshioka,∗2 andT. Uesaka∗1

NMR signal (a.u.)

3000

2500

2000

1500

1000

Build up time ~ 20 h

0
0

∗1
∗2
∗3

RIKEN Nishina Center
Department of Physics, Kyushu University
RIKEN Center for Advanced Photonics

1

2

3

4

5

6

Time [h]

7

8

9

10

A exp(-x/T)
Relaxation time ~ 28 hTime [h]Fig. 2. Polarization build up time (upper) and relaxation
time (lower) of the sample.

gle crystal of naphthalene doped with pentacene is used
as a filter. To polarize a huge crystal, a high-power laser
was implemented into the target chamber. We measured
the polarization build up time and relaxation time of thesingle crystal with a size of ϕ15 × 6 mm3 (Fig. 2). The
values are longer than assumed. As the next step, weare planning to optimize the strength of the laser andmicrowave, and the filter thickness. Then, we will checkthe performance of the neutron spin filter at RIKEN
Accelerator-driven compact Neutron source (RANS) in
March this year.
References

Fig. 1. Setup of the neutron polarization system using
Triplet-DNP.

103

500

NMR signal (a.u.)

A neutron spin filter using polarized 1 H media canpolarize the neutron beam passing through it because
the cross-sections have a large helicity dependence. 1 H
has a flat cross-section of 20 barn in the wide energy
range. Therefore, the spin filter of 1 H media is suitablefor epithermal neutrons. A polarized epithermal neutron beam is available, for example, in the T -violation
search in a compound nucleus.1) The solid state of 1 H
doped media is often polarized by Dynamic Nuclear Polarization (DNP). DNP is a technique of transferringspin polarization from electrons to nuclei by microwave
irradiation. We applied DNP with photo-exited triplet
electron spin (Triplet-DNP)2) because it can be used at
a higher temperature (>77 K) and in a lower magnetic
field (<1 T) compared to the conventional DNP method.
The neutron spin filter with Triplet-DNP was first developed at the Paul Scherrer Institut (PSI) in Switzerland.
They achieved 1 H polarization of 70% using a naphthalene crystal with a size of 5 × 5 × 5 mm3 in 0.36 T and at
25 K,3,4) and evaluated its performance using a polarized neutron beam in a meV region. We plan to preparea 1-cm-thick sample because a thick sample is suitable
for the polarization of epithermal neutrons. In addition,
we need a large acceptance of the spin filter in order toobtain high statistics. Therefore, we prepared a setupof the neutron spin filter with Triplet-DNP to polarize
such a huge sample, and it is shown in Fig. 1. The system is installed in the target chamber made of stainlesssteel, and the chamber is cooled with cold N2 gas.
Triplet-DNP is carried out at 0.3 T and 100 K. A sin-

1) T. Okudaira, 2018, PhD Thesis, Nagoya University, Aichi,
Japan.
2) A. Henstra, P. Dirksen, W. Th. Wenckebach, Phys. Lett.
A 134, 134 (1988).
3) M. Haag, B. van den Brandt, T. R. Eichhorn, P. Hautle,
W. Th. Wenckebach, Nucl. Instrum. Methods Phys. Res.
A 678, 91 (2012).
4) T. R. Eichhorn, N. Niketic, B. van den Brandt, U. Filges,
T. Panzner, E. Rantsiou, W. Th. Wenckebach, P. Hautle,
Nucl. Instrum. Methods Phys. Res. A 754, 10 (2014).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

Measurement of impurity nuclides in 10.75 MeV/nucleon 136 Xe beamin the atmosphere
T. Kambara∗1 and A. Yoshida∗1
On the basis of a fee-based facility sharing program,1)
private companies in Japan use 95 MeV/nucleon Ar and
70 MeV/nucleon Kr beams from the RIKEN Ring Cyclotron (RRC) to simulate single event eﬀects (SEE) of
semiconductor devices by high-LET components of thecosmic rays.2) Recently, the demand for heavier ionswith higher LET for the SEE test has signiﬁcantly increased, which has led us to prepare for fee-based Xeion irradiations. Because the samples are irradiatedin the atmosphere at RIBF, the beam passes throughvarious materials before the sample and fast secondary
nuclides produced by nuclear reactions in the materials
may contaminate the beam. We study the beam impurities with radiochemical measurements and previously
reported results for the Kr beam.3)
During a machine-study beamtime in February
2018, we measured the beam impurities of a
10.75 MeV/nucleon 136 Xe beam from RILAC2 and
RRC. The setup at the E5A beamline is shown in Fig. 1.
The beam spot was spread with a pair of wobbler magnets on the beam line. The beam passed through a
Kapton window with a thickness of 25 µm and diameterof 50 mm into the atmosphere, followed by an ionization chamber (IC), AE-1341S, which was produced by
Applied Engineering Inc,4) to measure the beam intensity.
In the IC, the beam passed four 6 µm thick mylar foils
and a 15 µm thick Al-foil electrode. A test sample of a
Si wafer (100 mm diameter and 0.5 mm thick) was attached directly to the exit of the IC to simulate semiconductor devices of clients. The total length of the beam
path in the atmosphere was approximately 39 mm. No
energy-degrader plates were used in these irradiations.
From the output-current measurement of the IC, thetotal number of primary Xe ions was estimated to beapproximately 1.17 × 1010 for a 10 minutes irradiation.
According to SRIM calculation,5) the energy of the primary Xe ions was approximately 2.3 MeV/nucleon at
the surface of the sample in which the ions stopped.
We measured the γ rays from the irradiated sample
with a Ge detector 12 times from 7 min to 17.2 days
after the irradiation. We analyzed the observed γ-ray
peaks according to the tabulated transition energies,
lifetimes, and branching ratios,6) and identiﬁed 15 radionuclides from 135 Xe to 159 Ho. Then, we extrapolated
the decay curves of the radioactivity to the end of theirradiation time to obtain the production probabilitiesof the radionuclides normalized to one incident 136 Xe
ion.
Figure 2 shows the obtained nuclide-production prob∗1

RIKEN Nishina Center

Fig. 1. Schematic diagram (left) and photograph (right) of
the setup of irradiation.

Fig. 2. Measured production probabilities of radionuclides.
Because the tabulated γ-emission probabilities of 158 Ho
are in the relative values, the maximum probability is
assumed to be 100% of the parent decay.

abilities. Because the Xe ions in the sample had much
lower energy than the Coulomb barrier, all the observed
radionuclides were produced in the upstream materials
and implanted in the sample. The ratios of the observed radionuclides in the beam were below 10−4 andthe total impurity would be below 1%.
Dy (Z = 66) and Ho (Z = 67) can be produced onlyin the Al electrode of the ionization chamber. We suppose that the Ho-isotopes were produced through thecomplete nuclear fusion reactions followed by multiple
neutron emissions, and the observed 155 Dy and 157 Dy
were mostly the daughters of 155 Ho and 157 Ho, respectively.
References

1) http://ribf.riken.jp/sisetu-kyoyo/ (in Japanesetext).
2) T. Kambara, A. Yoshida, RIKEN Accel. Prog. Rep. 48,
239 (2015).
3) T. Kambara, A. Yoshida, Record of 2018 IEEE Radiation Eﬀects Data Workshop (REDW), p. 94.
4) http://www.o-yo-giken.co.jp/ .
5) J. F. Ziegler, http://www.srim.org/ .
6) R. B. Firestone, Table of Isotopes (Wiley Interscience,1998).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

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 thecore server for the RIBF Linux cluster.
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) has been installed.
Figure 2 shows the mail trends in 2018. Approximately
50% of the incoming mails were blocked by the PMX
ip-blocker.
In order to improve the reliability of mails, we haveinstalled OpenDKIM and OpenDMARK software in
the mail server and mail gateway. DomainKeys Identified Mail (DKIM)2) is an email authentication method
designed to detect forged sender addresses in emails

Fig. 2. Mail trends:message categories in 2018.

(email spoofing), a technique often used in phishingand email spam. DMARC (Domain-based Message
Authentication, Reporting and Conformance)3) is anemail-validation system designed to detect and prevent
email spoofing, the use of forged sender addresses often
used in phishing and email spam. It is expected thatcombining DKIM and DMARC will reduce phishingand email spam.
The Integrated Digital Conference (INDICO) software4) has been operated at INDICO2.RIKEN.JP
since 2007. We replaced the hardware and softwareof this server in March 2018. HP DL-320G8 was installed for the new indico server. The indico software
was updated from indico 0.99 to 2.1.5. The new indico
software uses PostgreSQL database, while the previous
indico used Zope Object DataBase (ZODB) written in
Python. The migration of the database from ZODB
to PostgreSQL has been carried out.
Electric Log (ELOG)5) and MoinMoin Wiki6) for the
RIBF experiments were installed in the server RIBFEXP.RIKEN.JP in 2007. We have updated the ELOG
software from elog 2.1.4 to elog 3.1.4 and Wiki softwarefrom MoinMoin 1.5.7 to MoinMoin 1.9.10 in January
2019. HP ProLiant DL-20G9 was installed for the new
ELOG and Wiki server.
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. 51, 287 (2018).
2) https://en.wikipedia.org/wiki/DKIM .
3) https://en.wikipedia.org/wiki/DMARC .
4) https://docs.getindico.io/ .
5) https://elog.psi.ch/elog/ .
6) https://moinmo.in/ .

Fig. 1. Configuration of the RIBF Linux cluster.
∗1

RIKEN Nishina Center- 159 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 52 (2019)

CCJ operations in 2018
S. Yokkaichi,∗1 H. En’yo,∗1 T. Ichihara,∗1 W. Nakai,∗1 and Y. Watanabe∗1Overview
The RIKEN Computing Center in Japan (CCJ)1)
commenced operations in June 2000 as the largest oﬀsite computing center for the PHENIX2) experiment being conducted at RHIC. Since then, CCJ has been providing numerous services as a regional computing centerin Asia. We have transferred several hundred TBs of raw
data ﬁles and nDSTa) 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 2018, CCJ has contributed to 43 publishedpapers and 43 doctoral theses.
Computing hardware and software
The network conﬁguration and the computing hardware (nodes) and software (OS, batch queuing systems,
database engine, etc.) are almost same as described in
the previous APR.1) We have two login servers, one main
server (users’ home directory, NIS, DNS and NTP), andtwo disk servers whose disk sizes are 13 and 26 TB. The
main server has an external SAS RAID (21 TB) for thehome and work regions of users, and system usage. Also,
the server has a RAID with built-in disks (13 TB) which
can be 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 queuingsystem LSF 9.1.3.4) Table 1 lists the number 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,

Table 1. Number of malfunctioning HDDs in HP servers
during 2011–2018.
Type(Size)
SATA(1 TB)
SATA(2 TB)
SATA(4 TB)
SAS(146 GB)
SAS(300 GB)

∗1
a)

total
192
120
10
38
26

2018 ’17 ’16 ’15 ’14 ’13 ’12 ’11
16 18
8 14 11 16 20
9
2 10
2 10
0
2
5
4
0
3
1
5
3
2
0
1
1
0
1
0
1
1
0
0
1

RIKEN Nishina Centerterm for a type of summary data files in PHENIX

which have approximately 0.9 TB of library ﬁles. We
have two data-transfer servers, on which the grid environment8) is installed for data transfer to/from RCF.
Two new data-transfer servers will be in operation inearly 2019 and replace two servers being currently used.
Data transfer of the order of 100 TB from J-PARC and
BNL will be performed in the future. In addition, we
operate a dedicated server for the RHICf group9) andtwo servers for the J-PARC E16 group,10) in order tokeep their dedicated compilation and library environments along with some data.
A 10-KVA UPS (supplied by NTT Facilities) was discarded without battery exchange owing to its high costof exchange. The power wiring was relocated in Nov.
2018. Subsequently, a total power in our UPS system is30 KVA and a typical average load factor is 51% without jobs and 59% with maximum number of jobs in thecalculation nodes.
Joint operation with ACCC/HOKUSAI
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 ACCC11) and the joint operation with CCJ continued, including a new hierarchicalarchive system in which approximately 900 TB of CCJ
data are stored. Subsequently, the “HOKUSAI BigWaterFall” IA cluster, which has 840 nodes/33600 CPU
cores, was launched in 2017 by ACCC. Then a dedicated usage of legacy RICC 10 nodes by CCJ was ended
and the direct connection between CCJ and HOKUSAI
with the two 10G Ethernet links was also ended. CCJ
has not started to use the cluster because it does notsupport the NFS to share the computing environmentof PHENIX unlike RICC. Instead, we are in preparation to use one of the “container technologies” (such as“Docker” 12) ) to share the environment.
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) http://www.globus.org/toolkit/docs/
latest-stable/gridftp/ .
9) Y. Itow et al., arXiv:1409.4860 (Proposal).
10) S. Yokkaichi, RIKEN Accel. Prog. Rep., in this report.
11) http://accc.riken.jp/
12) https://www.docker.com/- 160 -

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. 52 (2019)

Eﬀects of asymmetrically-introduced splayed columnar defects on thepeak eﬀect in (Ba, K)Fe2 As2T. Tamegai,∗1 S. Pyon,∗1 A. Takahashi,∗1 A. Yoshida,∗2 and T. Kambara∗2
Iron-based superconductors (IBSs) are intensively
studied from both fundamental and applied aspects. In
particular, to make these materials practically appealing, the enhancement of critical current density, Jc , isindispensible. Columnar defects (CDs) introduced byheavy-ion irradiation are known to be very eﬀective toenhance Jc .1) The eﬀects of heavy-ion irradiation havebeen demonstrated in 122-type IBSs.2–4) Compared withheavy-ion irradiated Ba(Fe, Co)2 As2 , the Jc . in heavyion irradiated (Ba, K)Fe2 As2 has been enhanced up to ∼15 MA/cm2 . To further enhance Jc . in (Ba, K)Fe2 As2 ,we have introduced heavy ions in a splayed manner,
where CDs are introduced symmetrically from two directions (± θCD ) from the c-axis with the same dose
(Fig. 1(a)). We conﬁrmed that Jc in (Ba, K)Fe2 As2 canbe enhanced by ∼ 30% by choosing |θCD | = 5◦ .5) In thecourse of these studies, we discovered an anomalous peakeﬀect in (Ba, K)Fe2 As2 when the CDs are introduced atangles of |θCD | > 15◦ .5) The anomalous peak of Jc as afunction of magnetic ﬁeld appeared near 1/3B Φ (B Φ =nΦ0 , n: density of CDs, Φ0 : ﬂux quantum).
As described above, all splayed CDs have been introduced symmetrically with respect to the c-axis. Therefore, in this study, we introduced asymmetries to thesplayed CDs and measured its eﬀect on the anomalous
peak. All irradiations were done using a 2.6 GeV U beamat the RI Beam Factory at RIKEN Nishina Center at a
total dose of B Φ = 8 T (n = 4×1011 cm−2 ). Three typesof asymmetries were introduced. (1) We changed the average direction of two the types of CDs from the c-axis,
θCD = 20◦ ± 15◦ (Fig. 1(b)). (2) Instead of changing thedirection of two types of CDs, we made diﬀerent doses
for the two directions while maintaining the total dose,B Φ = 2 T and 6 T for θCD = −15◦ and +15◦ , respectively (Fig. 1(c)). (3) The splay plane is tilted, so that it
will have an angle ϕCD from the ac plane (Fig. 1(d)). Jc H at 20 K with various conﬁgurations of splayed CDs arecompared with the symmetric splayed CDs. It is obviousthat the introduction of asymmetry strongly suppresses
the anomalous peak eﬀect near 1/3B Φ .

Fig. 2. J c -H at 20 K with various configurations of splayed
CDs; (a) Comparison of (a) and (b) in Fig. 1, (b) Comparison of (a) and (c) in Fig. 1, and (c) Comparison of(a) and (d) in Fig. 1.

Fig. 1. (a) Standard splayed CDs. (b) Asymmetric splayed
CDs with the average direction away from the c-axis. (c)Splayed CDs with asymmetry in doses. (d) Asymmetric
splayed CDs with splay plane tilted away from the acplane.
∗1∗2

Department of Applied Physics, The University of Tokyo
RIKEN Nishina Center

References

1) L. Civale et al., Phys. Rev. Lett. 81, 45 (1991).
2) Y. Nakajima et al., Phys. Rev. B 80, 012510 (2009).
3) F. Ohtake et al., Physica C 518, 47 (2015).
4) T. Tamegai et al., Supercond. Sci. Technol. 25, 084008(2012).
5) A. Park et al., Phys. Rev. B 97, 064516 (2018).

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Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 52 (2019)

Control of the electrical conductivity in diamondby ion implantation
H. Yamazaki,∗1 T. Minamidate,∗2 M. Kidera,∗1 H. M. Yamamoto,∗3 R. Kato,∗2 and H. Ueno∗1
Although diamond is an insulator with a large bandgap of 5.5 eV, it becomes a semiconductor when dopedwith a small amount of boron (for p-type) or phosphorus(for n-type). Doped diamonds hold promise as the material for next-generation devices in place of the existing
Si- and GaAs-based semiconductors. In line with thisresearch trend, Ekimov et al. reported that B-doped diamond, when doped beyond the metal-to-insulator transition at nB ∼ 3×1020 cm−3 , shows superconductivity inthe samples grown by high-pressure—high-temperaturesynthesis.1) Using inelastic X-ray scattering from a CVD(chemical vapor deposition) grown sample, strong softening of the optical-phonon modes was admittedly observed in superconducting B-doped diamond near the
Brillouin-zone center.2) Theoretically, the superconducting critical temperature Tc can be raised substantiallyby reducing the eﬀects of disorder in the B-doping processes.3) For a higher Tc , more subtle control of doping using CVD and/or MBE (molecular beam epitaxy)
methods is highly required, whereas a diﬀerent method
based on ion implantation is also worth investigating
since it enables selective ion-doping in a controlled manner.
In this study, we try to control the electrical conductivity in diamond by means of the ion implantation technique, utilizing the beam facilities in RIKEN. For n- andp-type semiconductors (and possibly superconductors),
nitrogen and boron ions are implanted into diamond,
respectively. To create an n-type semiconductor by Ndoping is a challenging work, since nitrogen behaves as a
deep donor in diamond and does not contribute to conductivity.4) By changing the beam intensity and irradiation time, the concentration of the dopants in diamond
was controlled. The electrical conductivity of the doped
diamonds was measured using a four-probe conﬁguration. Magnetization measurements were carried out toFig. 1. Temperature dependence of the electrical resistanceR normalized to R (300 K) for B-doped diamonds.
∗1
∗2
∗3

RIKEN Nishina Center
Condensed Molecular Materials Laboratory, RIKEN
Institute for Molecular ScienceFig. 2. Temperature dependence of the magnetization for Bdoped diamonds.

elucidate the eﬀect of paramagnetic moments (due tolattice defects) and the emergence of superconductivity.
Raman spectroscopy and X-ray diﬀraction (XRD) studies were also performed.
Figure 1 shows the temperature dependence of theelectrical resistance R normalized to R (300 K) for Bdoped diamonds. Their doping concentrations are indicated in the ﬁgure. The fairly high dispersion of data
is supposedly due to bad electrical contact between the
conductive paste and the diamond surface. A modelof thermally-assisted hopping can provide a good ﬁt to
the experimental data. We are currently examining thephysical signiﬁcance of the ﬁtting parameters. The results of the magnetization measurements (Fig. 2) showthat our B-doped diamonds do not exhibit superconducting transitions at low temperatures, even though thedoping concentrations are nominally beyond the metalto-insulator transition at nB ∼ 3×1020 cm−3 . Annealing
treatment after the irradiation may be necessary for the
samples to show superconductivity. The temperaturedependence of the magnetization can be represented as
the sum of the Curie and temperature-independent components. The correlation between each component andthe doping concentration will be clariﬁed by preparing
the samples at higher concentrations.
As for the N-doped diamonds (e.g. at nN ∼ 7.5 ×
1021 cm−3 ), the results obtained by Raman spectroscopy
and XRD show that they were fully converted into amorphous carbon in the as-implanted state as well as after
annealing at 1000 K, likely due to radiation damage.
We have to further consider the implantation/annealing
process in order to minimize the lattice damage in diamonds.
References

1) E. A. Ekimov et al., Nature 428, 542 (2004).
2) M. Hoesch et al., Phys. Rev. B 75, 140508(R) (2007).
3) T. Shirakawa et al., J. Phys. Soc. Jpn. 76, 014711 (2007).
4) S. J. Sque et al., Phys. Rev. Lett. 92, 017402 (2004).

- 162 -

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 52 (2019)

Investigation of single event eﬀects observed in SiC-SBDs
Y. Nakada,∗1 E. Mizuta,∗1 S. Kuboyama,∗1 and H. Shindou∗1
Wide bandgap semiconductor devices such as GaN and
SiC are attractive for next-generation satellites to reduce
the energy losses in high-power and high-frequency systems. Although Si remains the dominant material usedin space systems, there is now a strong demand for new
and more eﬃcient devices. However, there are few reports about power-handling applications. For such use
in satellite power applications, the mechanisms of single
event eﬀects (SEEs) must be resolved at ﬁrst with someappropriate steps.
In this study, we report the results of evaluating SEEs
on SiC-Schottky barrier diodes (SiC-SBDs) for powerhandling applications. The ion species we used in theexperiment was 86 Kr, 1242 MeV. The ion range was
113 µm; LET was 27 MeV/(mg/cm2 ) at the device surface. Figure 1 shows the device structure. The SiCSBD in this study was a type of commercial oﬀ-the-shelf(COTS) 1200 V device.
It is known that the failure modes of SiC-SBDs are
separated into three regions as shown in Fig. 2.1) Region 1 is the non-destructive region where the collectedcharge is reproducibly measured with no damage. Region 2 is where there is a permanent increase in leakage
current and thus, we deﬁne “Region 2” as the permanent
damage region. Region 3 is deﬁned as the catastrophic
failure region where an SEE occurs. However, the causeof the transition from Region 1 to Region 2, and thento Region 3 has yet to be clariﬁed. We therefore focus
on the area of transition and discuss Region 1 and 2,
particularly in terms of experiments and simulation.
Figure 3 (left) shows the transition of the leakage current (Ir) at reverse bias condition after irradiation. In
Fig. 3 (left), Ir was shown not to increase up to 220 V
but increased above 240 V. We assume that the threshold between 220 V and 240 V is the area of transition
from Region 1 to Region 2. Figure 3 (right) shows theIr values at 220 V and 240 V during irradiation. Ir was
shown not to increase with Kr ﬂuence at 220 V but does
increase at 240 V.
Figure 4 shows the TCAD (technology computer-aided
design) simulation results of one particle traversing in
SiC-SBD by ECORCE.2) The parameters of SiC-SBDs
that we used were obtained by measuring the electricalcharacteristics. A calculated point in Fig. 4 was an in6FKRWWN\FRQWDFW
1HSL
1VXE

2KPLFFRQWDFW

Fig. 1. Device structure.

Fig. 2. Characteristic regions obs-

erved by heavy ion irradiations on SiC-SBDs.
∗1

Research and Development Directorate, Japan Aerospace Exploration Agency

Fig. 3. Ir values at each voltage after irradiation (left) and increase of Ir during irradiation at 220 V and 240 V (right).

Fig. 4. TCAD simulation results of one particle traversing in
SiC-SBD. (Vr = 220 V; solid line/Vr = 240 V; dashed line).

cident point of particles, directly below the electrode.
In Fig. 4, at ﬁrst, a particle traverses in a device withelectron-hole pairs being generated and thus, the electric ﬁeld was enhanced further. Second, the total current (Itot) was increased. Finally, the increase in current
causes the temperature of the calculated point to rise.
Compared to Vr = 220 V, the temperature value at Vr =240 V was remarkably high and above the melting point(3000 K) of the SiC crystal. Thus, the temperature exceeding the melting point is assumed to be one owing todevice deterioration.
In these experiments, we evaluated the area of transition between the three regions. To assess the experimental data, we conducted TCAD simulation of single
event eﬀects. This simulation was available to observe
the electron behavior inside SiC-SBDs when one particle makes an incident on a device. On comparing thebefore and after data, we found a signiﬁcant diﬀerence
regarding temperature at the incident point of particles.
Although certain issues regarding the simulation parameters remain to be resolved, the ability to simulate thecauses of SEE deterioration for power devices is necessary. To resolve these eﬀects, additional experiments are
required.
References

1) S. Kuboyama et al., IEEE Trans. 53, 6 (2006).
2) A. Michez et al., IEEE Trans. 62, 4 (2015).

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Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 52 (2019)

Energy dependence of MeV-ion microbeam size extracted from tapered
glass capillary optics
M. Ikekame,∗1,∗2 T. Ikeda,∗1,∗2 Y. Hikima,∗1,∗2 M. Mori,∗1,∗2 S. Kawamura,∗1,∗2 T. Minowa,∗2 and W. -G. Jin∗2
Tapered glass capillary optics, which is known as thecell injection needle in life sciences, is capable of producing micrometer-sized MeV ion beams. One of theadvantages of this microbeam optics is that the target
can either be in vacuum, air, or liquid because the endwindow at the capillary outlet keeps the vacuum level
inside the capillary. The end-window is fabricated to bethin enough to enable the passage of ions. It also contributes in the close approach of the capillary outlet to
the target even in air/liquid so that the broadening of the
microbeam size due to multiple-scattering is minimized.
An irradiation experiment on a small organ such as an
insect’s skin using a few MeV energy H/He ions provided
by the RIKEN Pelletron accelerator is scheduled to investigate the gene functions relevant to the developmentof the organ. The combination of MeV ions and the capillary realizes the damage conﬁnement in depth as wellas the pin-point lateral damage in the order of µm toensure that microscopic observation can be performed toﬁnd any change in the shape of the organ after the ion
irradiation. We aim at a spot size of several tens of µm
at an irradiation distance of 1 mm or beam divergence of1◦ . This report introduces the measurements of the spot
sizes and their positions.
Figure 1 shows the plastic end-window of the used capillary whose inlet/outlet sizes were 1.8 mm/9.9 µm, respectively. A 2.8 MeV H+ beam entered the capillary
mounted at the beam port of BL-W30 line (Fig. 2(a)).
The port has a θ-ϕ (horizontal and vertical) tilting system. The microbeam size and position were measured
by the knife-edge method with a step of 75 µm, assuming Gaussian shape. The extracted ions were counted
by a PIN photodiode, connected to the pre- and mainampliﬁers, discriminator and visual scaler.
Capillary optics is known to have a beam guiding effect. For keV ions, the ion transmission was observed
even when the capillary was tilted by up to 80 mrad.1)
The eﬀect for 2.8 MeV H+ was tested for the ﬁrst timein this energy region. The measured bending angle re-Fig. 1. Outlet of the capillary. The inner diameter and thethickness of the end-window are 9.9 µm and 9.1 µm, respectively. Inner diameter looks larger owing to the refraction index of borosilicate (1.473) for λ = 587.6 nm.
∗1∗2

RIKEN Nishina Center
Department of Physics, Toho University

Fig. 2. (a) Measurements of the size and position with knifeedge method. (b) The blue circles show the bending angles
as a function of the horizontal tilt angle.

Fig. 3. Microbeam profiles according to (a) ion energy and(b) number of thin Al layers.

constructed from the spot position in Fig. 2(b) shows theguiding for up to 9.0 mrad. However, the measured angles for a larger tilting exhibited degradation due to theasymmetric tails of the spots.
The measured spot sizes according to the ion energy
are shown as lines named 1–5 in Fig. 3(a). The ion energy
was selected by the pulse height of the main-ampliﬁer
output between the low-energy (1–3 V) and high-energy(7–10 V). Line 5 that represents the minimized energyloss events is the narrowest peak. The peak becomeswider for lower energy events. To obtain narrower microbeams by cutting the low-energy events, a stack of
Al-degrader foils was introduced behind the knife-edge.
Figure 3(b) shows the beam proﬁles changing the numberof foils of 11 µm thickness each. No ion was counted formore than three layers. The narrowest peak (398 µm in
FWHM) was obtained by three layers. The corresponding beam divergence is approximately 1◦ for each side,which is comparable to that of 3◦ of the laser microbeam
extracted from the same capillary for the laser sight system.2) The average energy and standard deviation of theions at the PIN photodiode are 1.08 MeV and 51.7 keV,
respectively, estimated by SRIM code.3)
References

1) T. Ikeda et al., Appl. Phys. Lett. 89, 163502 (2006).
2) K. Hirose et al., RIKEN Accel. Prog. Rep. 51, 193 (2018).
3) SRIM-2003, http://www.srim.org/ .

- 164 -

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 52 (2019)

Development of UV microbeam irradiation system by glass capillary optics
S. Kawamura,∗1,∗2 T. Ikeda,∗1,∗2 M. Mori,∗1,∗2 M. Ikekame,∗1,∗2 Y. Hikima,∗1,∗2 T. Minowa,∗1 and W. G. Jin∗1
The tapered glass capillary is known to be a powerfultool for producing ion microbeams. Many studies on ion
microbeam produced by the glass capillaries as well as
its application of irradiation to a living cell have beenreported.1) Several years ago, a group from Toho university and RIKEN started studies on the visible-light microbeams by glass capillaries.2) Recently, we have developed an ion microbeam irradiation system with a visiblelaser microbeam.3–5) Another irradiation setup based on
UV-laser microbeams will be newly introduced to a beamline of RIKEN Pelletron accelerator so that the ion andUV-laser microbeam irradiations can be switched quickly
without any changing around the sample stage. Thistime, we will report the details on the UV-laser microbeam proﬁles and the estimation of the beam energy
byglass
capillaryperthepulse([J])
by the optics.
glass capillary optics.
The glass capillary was fabricated from a straight glass
tube made of borosilicate, whose inner and outer diameters are 1.8 mm and 3.0 mm, respectively. The glass
capillaries were made using a puller (Narishige PE-22) byheating a straight glass tube and pulling both ends witha constant force. The outlet diameter a of the capillary
was determined using a microforge (Narishige MF-900).
Figure 1 shows the experimental setup for beam proﬁle measurement. In this measurement, we used a diodelaser with wavelength (λ) of 375 nm. A ﬂuorescentscreen was used to obtain the spot shape at the distanceL, called irradiation distance, from the capillary outlet.
The spot pictures were taken by a digital camera thatis installed behind a ﬂuorescent screen. Generally, thespot shapes for L > 1 mm and L < 100 µm are likea Fraunhofer diﬀraction pattern and a Fresnel pattern,
respectively,
which areare known
knownasasringspotpatterns
images for a parrespectively, whichallel beam entered a small circular aperture. In previous
study, the spot pictures with Ar+ laser with λ = 488 nm
were analyzed for L > 1 mm and L < 100 µm.4) We
will support the pin-point irradiation to the nucleus in aliving cell. Therefore, we deﬁned the irradiation distance(L = 17 µm) and obtained spot diameters D(FWHM)
for the microbeam. Figure 2 shows the results of D as

Mirror
Diode laser (375 nm)
Fluorescent screen
Glass capillary
Objective lensL

∗2

Toho University
RIKEN Nishina Center

Fig. 3. Density enhancement of the extracted laser beam for
λ = 375 nm with diﬀerent outlet diameters a.

a function of a at L = 17 µm. In this experiment, we
obtained smaller spots for smaller outlet capillaries without high-order rings like a Fraunhofer diﬀraction pattern.
The spot shapes are good for irradiating a small target
like the nucleus in a living cell.
Using a power sensor (Ophir PD-300) and photodiode(HAMAMATSU S2281), we measured the beam powerfor diﬀerent glass capillaries, and estimated the focusing
ability. To estimate the focusing ability of the capillaries,
we introduced density enhancement, which is the ratio
between the output beam density at the outlet and the
input beam density at the inlet.
Figure 3 shows the density enhancement for glass capillaries that have diﬀerent outlet diameters. This resultmeans that the tapered glass capillary has a strong focusing ability even for UV-laser beam (λ = 375 nm). In thenear future, we will install this system to the beam lineof the Pelletron accelerator and for biological irradiation.
References

MirrorFig. 1. Experimental setup for beam proﬁle measurement.
∗1Fig. 2. Spot diameters D(FWHM) for glass capillaries with
diﬀerent outlet diameters a. The input laser wavelength
was 375 nm. L is the irradiation distance.

1) T. Ikeda et al., Appl. Phys. Lett. 89, 163502 (2016).
2) W. G. Jin et al., J. Phys. Soc. Jpn. 84, 114301 (2015).
3) M. Koushima et al., J. Phys. Conf. Ser. 875, 112004 (2017).
4) K. Sato et al., RIKEN Accel. Prog. Rep. 51, 21 (2018).
5) K. Hirose et al., RIKEN Accel. Prog. Rep. 51, 193 (2018).

- 165 -

2. Atomic and Solid State Physics (Muon)

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Magnetic ordered states of hole-doped pyrochlore iridates(Y1−x−y Cux Cay )2 Ir2 O7 investigated by µSR
J. Angel,∗1,∗2 K. Matsuhira,∗3 and I. Watanabe∗1,∗2
The interplay between electron-electron correlationand spin-orbit coupling interaction leads to various exotic states in iridates such as Mott insulator, spin liquid,
and Weyl semimetal.1) Pyrochlore iridates, R2 Ir2 O7(R = Y and lanthanides) exhibit a largely systematic metal-insulator transition (MIT) among pyrochlore
systems and is observed with accompanying magnetictransition by changing R ion. The Ir atom is expected
to play a critical role because Ir has the large spinorbit coupling eﬀect, which is predicted to cause exotic magnetic properties in R2 Ir2 O7 . Among R2 Ir2 O7 ,Mott insulator Y2 Ir2 O7 (Y3+ : non-magnetic; Ir4+ : 5d5 )is an ideal system for the investigation of the magnetic properties of the Ir atom to clarify its origin.
This is because the Y atom does not possess any localized magnetic moments and exhibits the all-in allout magnetic ground state below the MIT temperatureof approximately 170 K.2–4) Further, the mechanism of
MIT should also be studied by doping holes to the system.5–7) A key issue on the Mott insulator is the holedoping eﬀect; therefore, we investigated the changes
in the magnetic properties of (Y1−x−y Cux Cay )2 Ir2 O7(x = 0.05) in which the hole concentration can be controlled by substituting Ca for Y.
The µSR measurement in the zero-ﬁeld condition(ZF-µSR) was carried out at the RIKEN-RAL Muon
Facility, Rutherford-Appleton Laboratory, in the UK
using a pulsed positive muon beam. We measured
the ZF-µSR time spectra of polycrystalline samples,(Y1−x−y Cux Cay )2 Ir2 O7 (x = 0.05) and analyzed themusing the following analysis function.
A(t) = A0 e−λt

(1)

In Eq. (1), A(t) is the asymmetry of the muon-spin
polarization at t, A0 is the initial asymmetry at t =0, and λ is the depolarization rate of the asymmetry
parameter.
Figure 1 shows the temperature dependence of A0
measured on (Y1−x−y Cux Cay )2 Ir2 O7 (x = 0.05) at various values of y. Sudden decreases in A0 were observedwith a decrease in the temperature of the samples up
to y = 0.10. This decrease in A0 was not observed for
y = 0.20 in the metallic state. The decrease implies theappearance of the fast depolarizing component causedby the slowing down of the ﬂuctuations of Ir spins. The
dashed lines in Fig. 1 indicate the onset temperatures
∗1
∗2
∗3

of the appearance of the magnetically ordered state in(Y1−x−y Cux Cay )2 Ir2 O7 (x = 0.05). It is clear that themagnetically changes in the electronic state from insulating to metallic. This study will be soon published.

RIKEN Nishina Center
Department of Condensed Matter Physics, Hokkaido University
Graduate School of Engineering, Kyushu Institute of Technology

Fig. 1. Temperature dependence of initial asymmetry, A0for (Y1−x−y Cux Cay )2 Ir2 O7 obtained from zero-fieldµSR measurements.

References

1) W. Witczak-Krempa et al., Annu. Rev. Condens. Matter
Phys. 5, 57 (2014).
2) S. M. Disseler et al., Phy. Rev. B 86, 014428 (2012).
3) D. Yanagishima, Y. Maeno, J. Phys. Soc. Jpn. 70, 2880
(2001).
4) N. Taira, M. Wakeshima, Y. Hinatsu, J. Phys. Condens.
Matt. 13, 5527 (2001).
5) H. Fukazawa, Y. Maeno, J. Phys. Soc. Jpn. 71, 2578
(2002).
6) L. Savary et al., Phys. Rev. X 4, 041027 (2014).
7) W. K. Zhu et al., Phys. Rev. B 90, 054419 (2014).

- 167 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Generalization of muon spin relaxation function to study the pseudogap
state of the underdoped La2-x Srx CuO4
M. D. Umar∗1,∗2 and I. Watanabe∗1,∗2
The origin of the partial gap in the charge and spin
sectors at the normal state of cuprate-based superconductors called, pseudogap state, and its interplay withthe superconducting state are still elusive. One study
proposed that the pseudogap state is a precursor of thesuperconducting state, while another study argued thatthe state is a competing order such as spin or charge density waves, stripes, and other exotic orders, for instance,d-density wave and circular current models.1)
The µSR technique is a sensitive tool to investigate
the static and dynamic behaviors of the internal magnetic fields. The previous µSR time spectra of the underdoped regime of La2-x Srx CuO4 showed that the initialline shapes change from the Gaussian-shape dependingon the temperature and doping concentration.2,3) At a
low temperature range, the characteristic temperaturesdue to the changes in the Gaussian-shape are related
to the formation of a spin glass system2) , and at a lowtemperature range and, at a higher temperature range,
they are correlated with a minimum resistivity from themetal-insulator crossover experiments.3) A product of
the Lorentzian and Gaussian functions can approach thechanges from the Gaussian-shape in the two previous
studies.2,3) In a fast fluctuation limit, the longitudinal
field dependence of the relaxation rate is described by
Redfield formula.4) However, the relaxation rate of theLorentzian function may represent static or dynamic internal fields on the muon site.5) Replacing the Gaussianor Lorentzian exponentials of the Kubo-Toyabe functions with a stretched exponential6) and convoluting theGaussian and Lorentzian probability density functions(PDFs)7) are two static scenarios that have been pro-

µs

Fig. 2. Calculated time spectra in the LF experiment for
all cases in Fig. 1, plotted for the same ratio of the applied longitudinal ﬁeld (γµ Bexp ) to the width distributions (∆, a).

posed earlier to fit the intermediate state of the line
shape between the Gaussian- and Lorentzian-shapes.
As an alternative for the static scenario due to thetiny changes in the Gaussian-shape, we propose a mixture of Gaussian and Lorentzian PDFs. In general, mixing two or more PDFs is interpreted in terms of either the non-normal behavior of the PDF or the presence of two or more subpopulations.8) Moreover, themixing of the Gaussian and Lorentzian PDFs can approach a convolution of the Gaussian and Lorentzian
PDFs.9) We apply the Kubo Golden Rule (KGR) formula to derive the muon spin relaxation functions resulting from the mixing of the Gaussian and Lorentzian
PDFs for both zero- (ZF) and longitudinal-field (LF)experiments. Our result shows that the mixture of theGaussian and Lorentzian PDFs can approach the convolution and stretched exponential scenarios. Our derivation also confirmed that the KGR formula for the LF
condition can analytically produce the Lorentzian part,which is contrary to a previous claim.10) The analysis
function of the mixture of the two PDFs exhibits initialslopes between the Gaussian and Lorentzian shapes inboth the ZF and LF conditions, whereas the depth andposition of a dip in the ZF lineshape change with theratio of the Gaussian and Lorentzian weighting factors.
Referencesµs

Fig. 1. The line shapes of the mixture of the Gaussian andLorentzian PDFs in the ZF conditions with three diﬀerent
ratios of weight factors (n) compared to the convolutionof the Gaussian and Lorentzian PDFs and the stretchedexponential scenarios plotted with the same width of theGaussian (∆) and Lorentzian (a) distributions.
∗1∗2

RIKEN Nishina Center
Department of Physics, Hokkaido University

1) T. Kirzhner, G. Koren, Sci. Rep. 4, 6244 (2014).
2) C. Panagopoulos et al., Phys. Rev. B 66, 064501 (2002).
3) I. Watabe et al., J. Phys. Soc. Jpn. 73, 2232 (2008).
4) R. S. Hayano et al., Phys. Rev. B 20, 850 (1979).
5) K. M. Kojima, Appl. Magn. Reson. 13, 111 (1997).
6) M. R. Crook et al., J. Phys. Condens. Matt. 9, 1149 (1997).
7) M. I. Larkin et al., Phys. Rev. Lett. 85, 1982 (2000).
8) G. McLachlan, D. Peel, Finite Mixture Model (John Wiley & Son, Canada, 2000).
9) T. Ida et al., J. Appl. Cryst. 33, 1311 (2000).
10) M. I. Larkin et al., Physica B 289–290, 153 (2000).

- 168 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Magnetic order in defective reduced graphene oxides (rGO)
investigated using µSR
R. Asih,∗1,∗2 M. A. Baqiya,∗1 D. P. Sari,∗3,∗2 Darminto,∗1 and I. Watanabe∗2
Several studies have investigated graphene-basedmaterials with a focus on molecular-based magnets.
In particular, reduced graphene oxide (rGO) is afascinating system that has numerous defects andfunctional group on its sheets; hence, it is ideal togenerate the magnetism of intrinsically nonmagnetic
graphene. rGO have been reported to exhibit various magnetic states including paramagnetic,1) weaksuper-paramagnetic,2) and room temperature ferromagnetic.3–5) These magnetic features are believed tobe related to the defect states in the rGO sheet.3,4,6)
A suﬃcient number of defects, especially in the formof vacancies and chemisorbed hydrogen, can lead tothe onset of magnetic ordering. Therefore, we intend
to further investigate a possible magnetic ordering inrGO prepared by the green synthesis method.7)
The presence of signiﬁcant number of defects anddiﬀerent types of oxygen functionality in the obtained rGO have been conﬁrmed by Raman, Fouriertransform infrared (FTIR), and photoemission spectroscopies. The defect concentration increases, whilethat of the oxygen functional group decreases whenrGO is thermally reduced at 1000◦ C (rGO-1000). Furthermore, an enhancement in magnetization was observed when the number of defect increases, conﬁrming defect-induced-magnetism in rGO. It was veriﬁedthat the magnetic impurities did not contribute toward enhancement of the magnetization. Thus, muon
spectroscopy (µSR) could help investigate the possible
onset of magnetism in rGO.
µSR measurements were performed on the obtained
samples, rGO and rGO-1000, under zero-ﬁeld (ZF) andlongitudinal-ﬁeld (LF) conditions. Figure 1 (a) shows
the ZF time spectra of rGO and rGO-1000 at 2 K. No
clear muon-spin precession was observed. Muon spin
depolarization is prominent up to 4 µs, then it is considerably slower in the range of 5–7 µs. Further, spin
depolarization is observed after 8 µs. These features
denote the appearance of the oscillation component on
the decaying signal; it is a typical feature of graphenebased compounds.8,9) Instead of magnetic ordering,the oscillation possibly indicates the nuclear dipolarinteraction between muon and proton.8) The changes
in the initial asymmetry and background along witha small increase in the relaxing amplitude for rGO1000 compared with that of rGO could be caused by
∗1
∗2
∗3

Department of Physics, Institut Teknologi Sepuluh Nopember, Indonesia
RIKEN Nishina Center
Department of Regional Environment Systems, Shibaura Institute of Technology- 169 -

Fig. 1. (a) Zero-field (ZF) time spectra of rGO and rGO1000 at 2 K. (b) Longitudinal-field (LF) time spectraof rGO-1000 at 2 K.

the increase in defect concentration. A missing fraction can occur in the samples when the positive muonstrongly interacts with an electron (hyperﬁne interaction) either due to the formation of muonium or after
the adduction reaction of muonium to form a radical.
To conﬁrm the cause, LF-µSR measurements were performed to decouple muon spin from the electron spin.
Figure 1 (b) displays the LF spectra of rGO-1000. The
decoupling is likely to occur owing to the applied ﬁeldof 100 G, which is much smaller than the ﬁeld required
to recover the free muonium signal (1580 G). This low
value demonstrates the formation of a radical complex
that was not detected in bare graphene.9) Further ﬁtting analysis concomitant with calculation work arerequired to verify these suggestions.
References
1) Sepioni et al., Phys. Rev. Lett. 105, 207205 (2010).
2) Sarkar et al., Phys. E Low-Dimensional Syst. Nanostruct. 64, 78–82 (2014).
3) Qin et al., Carbon 78, 559–565 (2014).
4) Khurana et al., Nanoscale 5, 3346–3351 (2013).
5) Sun et al., Nano Res. 7, 1507–1518 (2014).
6) Tǔcek et al., Chem. Soc. Rev. 47, 3899–3990 (2018).
7) Darminto et al., IEEE Trans. Mag. 54, 1–5 (2018).
8) Riccò et al., Nano Lett. 11, 4919–4922 (2011).
9) Gaboardi et al., J. Mater. Chem. A 2, 1039–1046 (2014).

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Ground state of quasi-one dimensional competing spin chain
Cs2 Cu2 Mo3 O12
T. Goto,∗1 K. Matsui,∗1,∗2 J. Angel,∗3 I. Watanabe,∗3 T. Sasaki,∗4 and M. Hase∗5
The ground state of the competing-spin chain
R2 Cu2 Mo3O12 1,2) has attracted much interest, not only
for the possibility of spin nematic state,3–7) but also because the two isomorphic compounds with R = Cs andRb show diﬀerent ground states.8–11) While the former
shows a magnetic order at T N = 1.8 K, the latter showsa small spin gap of ∆/kB = 1.6 K. Within a classical spinmodel, the competing spin chain with the ferromagnetic
J 1 for nearest neighboring spins and the antiferromagnetic J 2 for next nearest spins, the helical order is expected for |J2 /J1 | > 1/4. For both the two compounds
satisfy this condition, that is J1 = −93 and J2 = +33 K
for Cs, and −138 and +51 K for Rb, the diﬀerence intheir ground states may come from the quantum eﬀect ora tiny inter-chain interaction. As for the Cs-system, theexistence of magnetic order has so far been conﬁrmedby the speciﬁc heat7) and µSR8–11) at zero ﬁeld, andby NMR8–11) under ﬁnite ﬁelds. However, the observed
increase in NMR line width below T N becomes quite
small when the applied ﬁeld is lower than 2 T. That is,
the increase in FWHM of NMR spectrum below T N isdecreased from 400 Oe for the measurements above 3 T
to only 120 Oe for below 2 T. In order to investigate thespin state under low ﬁelds, we have performed LF-µSR
experiments on this compound.
Zero (ZF) and longitudinal (LF) ﬁeld-µSR measurements in the 3 He temperature range were performed
on a powder sample at Riken-RAL Muon facility using a spin-polarized pulsed surface-muon (µ+ ) beamwith a momentum of 27 MeV/c. The zero-ﬁeld muon
spin depolarization data were analyzed with the function GKT (τ ; σ)e−λτ , where G KT is Kubo-Toyabe function, σ ≈ 0.068 µsec−1 , the temperature independent
quasi-static ﬁeld distribution contributed from nuclear
moments and λ, the depolarization rate due to the dynamical spin ﬂuctuation.
With decreasing temperature, ZF-λ showed an abrupt
increase below TN = 1.8 K, supporting the results ofspeciﬁc heat and NMR.7,8) Under ﬁnite LF’s, the depolarization curves obeyed GKT (τ ; σ)e−λτ + P (∞), where
the constant P (∞) is the asymptotic value of muon spinpolarization at τ → ∞. P (∞) was dependent on HLF ,and for example, at 0.3 K, P (∞) increased monotonically from zero with increasing H LF and reached 0.8
above 3 kOe.12) There observed no initial drop in the
depolarization function even at the lowest temperature,indicating that the relaxing amplitude was decreased under higher H LF .
The temperature dependence of λ under various H LF
is shown in Fig. 1. Note here that λ(HLF ) is a measureof frequency component of γHLF in the electron spin
ﬂuctuation spectrum. One can see that in higher tem∗1
∗2
∗3
∗4
∗5

Sophia University
ISSP, University of Tokyo
RIKEN Nishina Center
IMR, Tohoku University
National Institute for Material Science

perature region above T N , λ is small and nearly independent of H LF , indicating that the spin ﬂuctuation has
a white spectrum.13) With decreasing temperatures, theweight of low frequency part of the spectrum increases
signiﬁcantly, showing the freezing of spin ﬂuctuation due
to the magnetic order. This is just analogous to our previous report where the slow down toward the Bose-glass
is shown.13) However, in the present case, the dynamical
spin ﬂuctuation persists even at lower temperatures far
below T N . At this stage we can only speculate that the
spins are in the quasi static ordered state, where only asmall static hyperﬁne ﬁeld is observed by NMR, and are
gradually stabilized with increasing applied ﬁeld. The
latter is in accordance with the increase in P (∞) and in
the hyperﬁne ﬁeld at higher ﬁeld.11) In order to conﬁrm
this speculation, µSR and NMR measurements under
the widerange of applied ﬁeld are necessary, and it is
now on the progress.

Fig. 1. Temperature dependence of dynamical component ofrelaxation rate λ under various longitudinal fields H LF .

References

1) M. Hase et al., J. Appl. Phys. 97, 10B303 (2005).
2) M. Hase et al., Phy. Rev. B 70, 104426 (2004).
3) M. Hagiwara et al., J. Phys. Conf. Ser. 320, 012049(2011).
4) H. Tsunetsugu et al., J. Phys. Soc. Jpn. 75, 083701(2006).
5) T. Hikihara et al., Phy. Rev. B 78, 144404 (2008).
6) M. Sato et al., Phys. Rev. Lett. 110, 077206 (2013); Phy.
Rev. B 83 (2011) 064405, B 79 (2009) 060406(R)7) A. Fujimura et al., IEEE Trans. on Mag. 99, 1100503(2016).
8) Y. Hoshino et al., JPS Conf. Proc. 3, 014012 (2014).
9) T. Goto et al., J. Phys. Conf. Ser. 828, 012017 (2017).
10) A. Yagi et al., J. Phys. Conf. Ser. 828, 012016 (2017).
11) K. Matsui et al., Phy. Rev. B 96, 22402(R) (2017).
12) K. Matsui et al., JPS Conf. Proc. 21, 011008 (2018).
13) T. Goto et al., Phy. Rev. B 78, 054422 (2008).

- 170 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Superconductivity in single crystals of λ-(BETS)2 GaCl4 studied bytransverse-field µSR
D. P. Sari,∗1,∗2 K. Hiraki,∗3 R. Asih,∗4,∗2 I. Watanabe,∗2 and Y. Ishii∗1
The superconducting gap structure in λ(BETS)2 GaCl4 is intriguing and has been consistently
studied using µSR. We performed transverse field (TF)
µSR at fields of 150 Oe down to 0.3 K using a 120 mg
randomly oriented sample, at the ISIS Muon Facility in
the UK. The temperature dependence of the superfluid
density deduced from that experiment is best describedby the s + d-wave with a dominant s-wave component.1)
In order to get clearer and more direct evidence in termsof the superconducting gap structure determination, we
performed similar measurements using a 75 mg wellaligned sample by applying the external field perpendicular to the conducting ac-plane. Here, we report the
TF dependence of the London penetration depth, whichleads to the upper critical field H c2 estimation, in orderto check the quality of the experimental setup in aligned
single crystals of λ-(BETS)2 GaCl4 .
Figure 1 shows a typical TF-µSR spectra with a fieldof 150 Oe in the aligned single crystals at T = 0.3 K
and 10 K after being cooled through critical temperature
Tc ∼ 5.3 K.
The time spectra were fitted by using Eq. (1),()2
A(t) = 0.3438 × e−(σt) cos γµ Hint1(sample) t + ϕ)((1)+ 0.652 cos γµ Hint2(Ag foil) t + ϕ

The two oscillation components represent about 35%
signal from the sample and 65% signal from the silver
package. The damping rate σ becomes prominent oncethe system enters the superconducting state. The superconducting component of the damping rate σSC is222= σ 2 − σNM, where σNMis the signal
then given by σSCσT =10 K in the normal state due to the nuclear moments.
Furthermore, the TF dependence of σSC can be used todetermine the London penetration depth λ and to givean estimate for the Hc2 , following Eq. (2),Fig. 1. The normalized TF time spectra in the applied field of
150 Oe measured at T = 0.3 K (black) and 10 K (green).
The red and black solid lines are the best-fit results obtained by using Eq. (1). The trace of the envelope of thecosine curve represents the damping rate σ of Eq. (1).

(2)

Fig. 2. Transverse-field dependence of damping rate of themuon-spin precession in the superconducting state, σSC ,of λ-(BETS)2 GaCl4 taken at 0.3 K. The red and green
circles indicate the data for randomly oriented and welloriented crystals, respectively. The inset figure shows thealigned crystal mounted in a silver foil. The black arrow
indicates the direction of the applied field.

where Happ = 150 Oe and λis in nm.2)
Figure 2 shows the estimation of H c2⊥ from the measurements of the aligned crystals. The resulting Hc2⊥ ,which is parallel to the b-axis, is 41 ± 19 kOe, and theabsolute value of the London penetration depth at 0 K,
λ(0) = 710 ± 12 nm. The estimation of H c2 from theprevious TF-µSR measurement on a randomly oriented
sample was 43±25 kOe.1) From magnetoresistance measurements, the H c2 of λ-(BETS)2 GaCl4 was reported tohave a high anisotropy. The H c2 parallel to a, b, andc-axes were 150 kOe, 30 kOe, and ∼ 130 kOe, respectively.3) In comparison with the H c2 in the randomly oriented crystals, the estimation of H c2⊥ is closer to the reference of the magnetoresistance measurement, although
the signal we obtained from the sample was smaller thanthat of the background from silver. It implies that the
sample alignment was good enough. Taking into accountthe low sample mass, we will increase it up to ∼ 120 mg
in order to obtain a stronger signal and solid results.

√

[
)3 ]
(
√
λ−2
2σSC (H) = 4.83 × 104 × (1 − Happ /Hc2 ) × 1 + 1.21 1 − Happ /Hc2

∗1
∗2
∗3
∗4

Graduate School of Engineering and Science, Shibaura Inst.
of Tech.
RIKEN Nishina Center
Department of Physics, Fukushima Medical University
Institut Teknologi Sepuluh Nopember

References

1) D. P. Sari, et al., to be submitted.
2) E. H. Brandt, Phys. Rev. B, 68, 054506 (2003).
3) M. A. Tanatar, et al., Supercond. 12, 511 (1999).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)µSR study on ferrimagnetism of Na-K alloy clusters incorporated
into zeolite LSX under high-pressure helium gas
T. Nakano,∗1 L. M. Kien,∗2 I. Watanabe,∗3 R. Asih,∗4,∗3 Y. Ishii,∗5 M. Kibble,∗6 C. Goodway,∗6 C. Oﬀer,∗6
and R. Done∗6
Various types of magnetic orderings such as ferromagnetism, antiferromagnetism, and ferrimagnetism
have been found in three dimensionally arrayed alkalimetal nanoclusters in zeolite crystals.1) The magnetic
properties depend on the structure of the zeolite,
species of the alkali element, and electron density of
the clusters. They are a new class of magnetic materials because their magnetic orderings are realized by themutual interactions between the s-electrons and they
contain no magnetic elements.
In zeolite LSX (low-silica X), β-cages with an innerdiameter of 7 Å are arrayed in a diamond structure.
A supercage with an inner diameter of 13 Å is formed
between the β-cages. The supercages are also arrayedin a diamond structure. It is known that an N-typeferrimagnetism appears when Na-K alloy clusters areincorporated into zeolite LSX (Na4 K8 Al12 Si12 O48 persupercage) by loading K atoms for a certain range ofthe loading density. The highest Curie temperature TC
is approximately 20 K. Recently, we found that a new
ferromagnetic phase with TC as high as 60 K is formed
on applying pressure using helium gas. Because theformation of the new magnetic phase has a slow timedependence and is irreversible, it is speculated that thehelium atoms are loaded into the pores of the zeolite
crystal by pressure and directly change the electronic
states of the clusters resulting in the enhancement of
the magnetism. In this work, we performed µSR measurements on this system under a high-pressure heliumgas to investigate the new magnetic phase.
A high pressure cell newly made of Ti alloy wasloaded with a powder sample of K-loaded LSX. This
sample shows a ferrimagnetic ordering below 20 K atambient pressure. µSR measurements were performedat the RIKEN-RAL Muon Facility in the U. K. The
pressure cell was loaded into the VARIOX cryostat
and connected to a high-pressure He gas handling system which allowed us to control the pressure at any
temperatures.2) We used a double-pulsed decay muon
beam with a momentum of 64.3 MeV/c. Zero-ﬁeldµSR spectra were obtained by utilizing the ARGUS
spectrometer.
The obtained spectra showed slow relaxations. At
50 MPa, the initial asymmetry A0 of the spectrum

gradually decreased below ≃ 90 K and quickly below≃ 20 K, as shown in Fig. 1. The decrease in A0 indicates that the muon spin is depolarized within the time
resolution of the measurement, ≃ 0.4 µs, owing to theappearance of a strong internal magnetic ﬁeld. After
reducing the pressure, the decrease in A0 below ≃ 90 K
disappeared, as seen in Fig. 1. Therefore, the gradualdecrease in A0 at 50 MPa can be attributed to thehigh TC magnetic phase. The phase transition is not
sharp. This may be due to a distribution of TC originating from a certain inhomogeneity of the He atom
loading. At 50 MPa, the ambient pressure phase withTC ≃ 20 K still remained. thereby indicating a phaseseparation. A part of the crystal may be loaded with
He atoms by pressure. The amplitude of the decreasein A0 for the high TC magnetic phase is approximetely
half of that in the 20-K phase at an ambient pressure.
This result indicates that although there are some inhomogeneities, the high TC magnetic phase has suﬃcient volume and can be regarded as bulk magnetism,
which does not originate owing to any impurities.

∗1

References

∗2
∗3
∗4
∗5
∗6

Institute of Quantum Beam Science, Ibaraki University
Hanoi University of Science, Vietnam National University
RIKEN Nishina Center
Department of Physics, Institut Teknologi Sepuluh Nopember
Department of Physics, Shibaura Institute of Technology
ISIS, Rutherford Appleton Laboratory- 172 -

Fig. 1. Initial asymmetry of the µSR spectra of Na-K alloy
clusters in zeolite LSX as a function of temperature.
The red circles are data taken at 50 MPa and the blue
circles are those after reducing the pressure.

1) T. Nakano, Y. Nozue, Adv. Phys. X 2, 254 (2017).
2) I. Watanabe, Y. Ishii, T. Kawamata, T. Suzuki,
F. L. Pratt, R. Done, M. Chowdhury, C. Goodway,
J. Dreyer, C. Smith, M. Southern, Physica B 404, 993(2009).

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Quantum eﬀects of muon on the electronic state of La2 CuO4
M. R. Ramadhan,∗1,∗3 M. I. Mohamed-Ibrahim,∗2 S. Sulaiman,∗2 and I. Watanabe∗1,∗2,∗3
Muon spin relaxation (µSR) studies on La2 CuO4
(LCO) prove the appearance of the antiferromagnetic(AF) long-range ordering as previously observed bypowder neutron diﬀraction experiments.1) The appearance of coherent muon-spin precession was observed andthe internal ﬁeld at the muon site was determined tobe approximately 410 G.2) Neutron diﬀraction experiments determined the AF spin structure, where the Cu
spin had the magnetic moment of 0.5 µB aligning to theb-axis in the CuO2 plane. Recent µSR studies on thethin ﬁlm reported the observation of another muon-spin
precession component, which experienced less internalﬁeld at the muon site of approximately 100–120 G.3) Although both µSR and neutron diﬀraction experiments
sense the same Cu spin in LCO, it is not yet possible
to explain the internal ﬁelds at the muon site by using
the AF spin structure as proposed by neutron diﬀraction experiments because the position of the implanted
muon has not been precisely determined to explain theelectronic state.
To deduce more detailed information and knowledge
from the µSR results, we are developing techniques tomore precisely estimate the muon position in LCO using
the density functional theory (DFT) calculations. The
Hubbard parameter U and exchange parameter J were
set to be 8 and 0.8 eV, respectively. The AF spin structure proposed by Vaknin et al. was considered in our
non-collinear calculations. To obtain a realistic behavior of muon, we utilized a large 32-unit supercell with asingle muon implanted in the lowest position as shownby the electron potential map as reported in the previous study,4) resulting in the perturbed system. We also
consider the unperturbed system, which is the same supercell with no implanted muon to capture the essential
diﬀerences between the perturbed and unperturbed systems. The ground state of the supercell was achievedby setting the convergence criterion to be 1 × 10−5 eV
and relaxing all atoms until the magnitude of the force
on each atom became less than 0.05 eV/Å. The dipole
ﬁeld value perceived by muon was evaluated using thespin-density grids acquired from our DFT calculations,
given by the following equation:]∑ 1 [(⃗r −⃗ri )SS3(⃗
ρi ·(⃗r −⃗ri ))
−⃗
ρi
(1)
Hdip (⃗r) =|⃗r −⃗ri ||⃗r −⃗ri |2i
Where ρ⃗i S is the magnetic moment of the Cu spin and|⃗r −⃗ri | is the relative distance between the muon and Cu
spins. The total internal ﬁeld at the muon site, Hdip (⃗r),
is obtained from the summation of all dipole ﬁelds due
∗1
∗2
∗3

Department of Physics, Universitas Indonesia
School of Distance Education, Universiti Sains Malaysia
RIKEN Nishina Center

Fig. 1. Comparison of spin density map of LCO for (a) unperturbed system and (b) perturbed system.

to the surrounding Cu spins. For our calculations, we
set the spherical region centered by the muon with aradius of 50 Å. This spherical region is suﬃcient for theconvergence of the calculated internal ﬁelds.
Figure 1 shows the spin density contour map between
the unperturbed (a) and perturbed (b) systems. Our
calculations indicate that the unperturbed system is an
AF insulator with 0.61 µB and an insulating gap ∼ 2 eV,
which signiﬁcantly corresponds with the experimental
data.5) The perturbed system, however, shows a local
deformation in both crystal and spin structure owing
the implanted muon. The nearest Cu spins are aﬀectedby the presence of the muon, thereby slightly reducing
the value of Cu magnetic moment to 0.58 µB . These
local deformations do not aﬀect the electronic structure in general as the muon only aﬀects the surrounding
atom, making a large supercell necessary in our studies. Using Eq. (1), we evaluated the dipole ﬁeld value ofthe muon inside our perturbed system and obtained avalue of 498 G, which is close to the experimental valueof 410 G. The diﬀerence of ∼ 80 G can be attributed totwo possible issues. The ﬁrst issue is the considerationof the zero-point vibrational motion for the implanted
muon. The second is the utilization of a more optimized supercell structure to get a better description on
how the implanted positive muons aﬀect the crystal andspin structure. We believe that these two key points aremandatory to obtain more information from the muon’s
position inside the system.
References

1) D. Vaknin et al., Phys. Rev. Lett. 58, 2802 (1987).
2) J. I. Budnick et al., Phys. Lett. A 124, 103 (1987).
3) E. Stilp et al., Phys. Rev. B 88, 064419 (2013).
4) M. R. Ramadhan et al., RIKEN Accel. Prog. Rep. 51,
197 (2017).
5) J. M. Grinder et al., Phys. Rev. B 37, 7506 (1988).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Ab-initio calculation and µSR study of the covalency eﬀect in
YBa2 Cu3 O6
I. Ramli,∗1,∗2 S. S. Mohd-Tajudin,∗3 S. Sulaiman,∗3 M. I. Mohamed-Ibrahim,∗3 and I. Watanabe∗1,∗2
Since the ﬁrst discovery of high-Tc in cuprates overthree decades ago, extensive studies of their magnetic properties have been carried out in order to explain the mechanism of superconductivity. YBa2 Cu3 O6(YBCO6 ), which is the mother compound of the high-Tc
cuprate YBa2 Cu3 O6+x , shows long-range antiferromagnetic (AF) ordering with the Néel temperature TN =420 K. The AF ordering in this system arises from thestrong on-site coulumb repulsion between electrons, and
it is destroyed by changing the oxygen content, which
results in superconductivity. A detailed understandingof the electronic structures and magnetic states regarding the mother compound and its chemical derivatives is
the key to understand the nature of superconductivity.1)
We studied the covalency eﬀect on the magnetic properties of YBCO6 by ab-initio calculations through thedensity functional theory (DFT) and the muon-spin resonance (µSR) technique. The µSR experiment involves
the implantation of muons into the system, and this provides information on the internal ﬁeld at the muon site,which is very important when discussing the electronicand spin states of the system.
We have carried out µSR experiments on single crystals of YBCO6 and detected three distinct muon-spin
precession components. This result suggests that three
diﬀerent muon sites exist in YBCO6 with internal ﬁeldsof 117.7 G, 295.5 G, and 220.4 G. In order to get a deeper
understanding of this result, we tried to estimate themuon-sites by ab-initio calculations and calculate theinternal ﬁelds at these muon sites. Since DFT fails to
consider the strong correlation eﬀect in a system such as
YBCO6 , an additional Hubbard parameter, U, was incorporated into our ab-initio calculations (DFT+U).2)
The DFT+U calculations found three local minima inthe potential, which can be regarded as initial muonsites in the system since muon has a positive charge.
These positions, marked as M1, M2, and M3, are shownin Fig. 1.
The muon perturbation to the host system was calculated by placing one muon at each initial muon site ina large 4 × 4 × 2 supercell and allowing all ions in the
supercell to relax. The large supercell is required to accomodate the behaviour of the muon as an ultra dilute
impurity in the host system. In the last step, we calculated the internal ﬁeld at each relaxed muon positionon the basis of dipolar interaction between the muonand the magnetic ions. The calculated internal ﬁelds
at the muon sites on the basis of ionic picture of magnetism, where spins reside in particular ions, are larger
∗1
∗2
∗3

RIKEN Nishina Center
Department of Condensed Matter Physics, Hokkaido University
School of Distance Education, Universiti Sains Malaysia

Fig. 1. The muon site positions from DFT+U calculations.

Fig. 2. The diﬀerences between the calculated and experimental values of the internal ﬁelds as functions of the Uvalue.

than those deduced from the experiments, although thezero point vibration energy of muons was carefully considered.
The covalency eﬀect, which arises from the strong hybridization between the Cu 3d and the O 2p orbitals, isthought to play a crucial role in this discrepancy. Thiseﬀect causes the extention of spin density in the real
space, although it is contradictory to the ionic pictureof magnetism. The DFT+U calculations have the capability to provide the spin density and have successfully
explained the ambigous missing intensity in copper oxide
compounds.3) Finally, we examined the internal ﬁelds at
the muon sites on the basis of the spin density criterion.
The internal ﬁeld at each site has a strong dependence on
the U value. Careful tuning of the U value was required.
The diﬀerences between the calculated and experimental values of the internal ﬁelds are shown as functions of
the U value in Fig. 2.
References

1) B. Keimer et al., Nature 518, 179–186 (2015).
2) J. Orenstein, A. J. Millis., Science 228, 468–474 (2000).
3) A. C. Walters et al., Nature 5, 867–872 (2009).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Studies of electrical conductivity in 12-mer single-stranded DNA byusing scanning tunneling microscope
H. Rozak,∗1,∗2 W. N. Zaharim,∗2 I. Miyazaki,∗3 K. Ichimura,∗3 M. I. Mohamed-Ibrahim,∗2 M. R. Samian,∗4
S. Sulaiman,∗2 and I. Watanabe∗1,∗2,∗3
DNA is a molecule that stores genetic instruction inliving things for making other large molecules. The
main structure of DNA consists of sugar phosphates andbases. There are four kinds of bases in DNA, namely
adenine (A), guanine (G), cytosine (C), and thymine(T).1) These bases contain a ring of atoms known as anaromatic group, and they are electron-rich in nature. If
their electron clouds overlap within the bases, π-π interactions are created and become a medium of electrontransport.2)
Electron transport in DNA is important in biological processes, especially for understanding the DNA
damage and repair mechanisms. According to previous
studies,3,4) electrons travel through the DNA to scan
the damaged area and repair it by using repair protein.
Therefore, the main question here is whether DNA isan electrical conductor or not? If DNA is conductive,
how do the electrons move along the DNA strand?
In order to answer this question, we carried out scanning tunneling microscope (STM) measurements on asimple sequence DNA. Our samples were composed of
12-mer single stranded synthetic DNA (12-mer ssDNA),and each strand had only one type of base (12mer-ssG,
12mer-ssC, 12mer-ssA or 12mer-ssT). In this report,
however, we only show the results of cytosine.
We prepared our 12mer-ssC sample for STM measurements by dissolving of 0.1 mg of powder sample in
2 ml pure water. This solution was shaken by using

Fig. 1. STM image of 12 mer single stranded cytosine
molecule aligned in a one-dimensional chain structure.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
School of Distance Education, Universiti Sains Malaysia
Department of Engineering, Hokaido University
School of Biological Sciences, Universiti Sains Malaysia

Fig. 2. Schematic picture of the electron tunnelling fromthe highest molecular orbital (HOMO) of the tip to thelowest molecular orbital (LUMO) of the sample.

an ultrasonic vibrator for about 60 min. Then, we deposited a droplet of the sample on a graphite stage anddried it in a space lined with silica gels for about 2 h.
The values of the bias voltage and current we used in
our STM measurement were 1.0 V and 0.1 nA, respectively.
From our STM measurements, we successfully observed the molecule image of 12mer-ssC as shown in
Fig. 1. This means that the sample is conductive.
We understood that electron tunneling occurs from thehighest molecular orbital (HOMO) of the tip to the lowest molecular orbital (LUMO) of the sample. Besides,
we also observed that the sample molecules are aligned
parallel to each other forming a one-dimensional chain
structure. Figure 1 shows the STM image of sample
in a one-dimensional chain structure. This structure
might cause electron transfer in a one-dimensional passacross the edges of the molecules, due to the overlapping of π orbitals between the strands of molecules.
This result agrees well with the results of muon spin
relaxation: electron transport occurs in the quasi onedimensionality at room temperature.
References

1) L. Pray, Nature Education 1, 100 (2008).
2) D. M Eley, D. I. Spivey, Trans. Faraday Soc. 58, 411(1962).
3) E. O’brien et al., Science 355, eaag1789 (2017).
4) Grodick et al., Biochemistry 54, 962–973(2015).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Magnetic ordering of (Eu1-x Cax )2 Ir2 O7 studied using muon spin
relaxation (µSR)
U. Widyaiswari,∗1,∗2 J. Angel,∗1,∗3 H. Nomura,∗4 T. Taniguchi,∗4 K. Matsuhira,∗4 B. Kurniawan,∗2 andI. Watanabe∗1,∗2,∗3
Pyrochlore oxides have been studied extensively because they show various physical properties such as superconductivity,1) spin-glass-like transition,2) possibility of a spin liquid state,3) and metal-insulator transition (MIT).4,5) Pyrochlore lattices have a network of
corner-sharing tetrahedra, which makes these systems
geometrically frustrated. Pyrochlore iridate series is
one of those frustrated systems. In pyrochlore iridates,
R 2 Ir2 O7 (R is the 4f rare element), the electronic properties vary with the changing value of R. Previous study
showed MIT at T MI accompanied by a magnetic transition in Ir4+ . The T MI decreases with an increase in the
R 3+ ionic radius and MIT disappears between R = Nd
and Pr.5) In Eu2 Ir2 O7 (T MI = 120 K), Eu3+ is a nonmagnetic ion (J = 0; 4f 6 ).5) Accordingly, the orderedstate of Ir4+ magnetic moment can be directly examined. This study aims to investigate the hole-doped
eﬀect on the magnetic properties in (Eu1-x Cax )2 Ir2 O7 .
Polycrystalline samples were synthesized using thesolid-state reaction and characterized by measuring themuon spin relaxation (µSR). The measurement was
conducted at the RIKEN-RAL Muon Facility in the
United Kingdom using a single pulsed muon beam. The
samples were measured in zero-ﬁeld condition in a temperature range between 1.6 and 200 K.
The results of µSR measurement were plotted in thezero-ﬁeld µSR (ZF-µSR) time spectra, which can be analyzed and ﬁt using the Lorentzian relaxation function,
as shown in Eq. (1).
A(t) = A0 exp(−λt)(1)

This function expresses the muon spin relaxation. A0
is the initial asymmetry at t = 0 and λ is the relaxation
rate of the muon. Figure 1 shows the ZF-µSR time spectra, where the solid line represents the best-ﬁt results.
The corrected asymmetry is obtained by subtracting
the background components from its asymmetry. It
decreases with a decrease in temperature, thereby indicating the existence of an ordered state. The temperature dependence of normalized asymmetry for various
x is shown in Fig. 2. It can be seen for x = 0.035 and
0.07, the ordered states appear in the samples with onset temperature around 100 K. However, for x = 0.13,
there is no ordered state. The result indicates that themagnetic volume fraction decreases with an increase in
the concentration of Ca.
∗1
∗2
∗3
∗4

Fig. 1. Zero-field µSR time spectra of (Eu1-x Cax )2 Ir2 O7
measured at several temperatures.

RIKEN Nishina Center
Department of Physics, Universitas Indonesia
Department of Condensed Matter Physics, Hokkaido University
Faculty of Engineering, Kyushu Institute of Technology

Fig. 2. Temperature dependence of (a) normalized asymmetry and (b) muon relaxation rate obtained from theanalysis of ZF-µSR time spectra of (Eu1-x Cax )2 Ir2 O7 .

From the result of µSR, it can be concluded thathole doping diminishes the magnetic ordered state of
the sample. The eﬀect of hole doping on magnetic ordered states and the physical properties of this system
must be investigated by comparing the result of µSR
obtained here with those obtained in other macroscopic
studies.
References
1) M. Hanawa et al., Phys. Rev. Lett. 87, 187001 (2001).
2) Y. Ito et al., J. Phys. Chem. Solids 62, 337 (2001).
3) L. Balents, Nature 464, 199 (2010).
4) K. Matsuhira et al., J. Phys. Soc. Jpn. 76, 043706 (2007).
5) K. Matsuhira et al., J. Phys. Soc. Jpn. 80, 094701 (2011).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)µSR study of the Cu-spin correlation in the electron-underdoped
Pr1.3-x La0.7 Cex CuO4+δ (x = 0.05) single crystals
T. Adachi,∗1,∗2 K. Kawabata,∗2 S. Onishi,∗2 A. Takahashi,∗3 Y. Koike,∗3 and I. Watanabe∗1

∗1

∗2
∗3

18

Pr1.3-xLa0.7CexCuO4+δ

16

Raw Asymmetry (%)

It has widely been believed in electron-doped highT c cuprates with the so-called T’-structure that an
antiferromagnetic (AF) order is formed in a parent
compound and underdoped samples. Formerly, however, it has been reported that the superconductivity
appears even in the parent compound and underdoped
samples through the appropriate reduction of excess
oxygen from as-grown thin ﬁlms1) and polycrystals,2)
resulting in a completely diﬀerent phase diagram fromthat formerly obtained. These suggest that the superconductivity in the electron-doped cuprates cannot
be understood in terms of carrier doping into Mott
insulators as in the case of the hole-doped cuprates.
Moreover, a raising question is whether or not the Cuspin correlation is developed in superconducting (SC)samples.
Recently, through improved reduction annealing,
we have prepared SC single crystals of the underdoped Pr1.3-x La0.7 Cex CuO4+δ (PLCCO) with x =0.05 − 0.10 whose ground states had been believed to
be AF.3,4) Our recent zero-ﬁeld (ZF) µSR measurements of PLCCO with x = 0.104,5) have revealed that,through the reduction annealing, a long-range AF order changes to a short-range one coexisting with thesuperconductivity. Moreover, it has been found thatthe further reduction brings about the destruction of
the short-range AF order and the increase in the SC
transition temperature T c . However, in samples withhigh T c values, the Cu-spin correlation has been foundto be developed at low temperatures, suggesting theintimate relation between the developed Cu-spin correlation and superconductivity.
In order to investigate the doping dependence of
the Cu-spin correlation, we have performed ZF-µSR
measurements of lightly electron-doped PLCCO withx = 0.05 using a MiniCryo at RIKEN-RAL.
For the as-grown sample of x = 0.05, it has beenfound that a long-range AF order is formed below the
Neel temperature TN ∼ 250 K and T N decreases downto ∼ 110 K for the moderately reduced sample. Figure 1 shows ZF-µSR time spectra of the further reduced sample of PLCCO (x = 0.05) with Tc ∼ 27 K. It
is found that the spectrum at 200 K shows slow depolarization of muon spins due to nuclear dipole ﬁelds at
the muon site. With decreasing temperature, the depolarization of muon spins becomes fast gradually andthe muon spin precession is observed below ∼ 100 K,
RIKEN Nishina Center
Department of Engineering and Applied Sciences, Sophia
University
Department of Applied Physics, Tohoku University- 177 -

x = 0.05

1412
10

T = 200 K
150 K
110 K
100 K
80 K
10 K

8
6

0

2

4

6

8

Time (µsec)

10

12

14

Fig. 1. Zero-field µSR time spectra of the further reduced
Pr1.3-x La0.7 Cex CuO4+δ (x = 0.05) with Tc ∼ 27 K.

indicating the formation of a long-range AF order. At
the lowest temperature of 10 K, however, it is foundthat the slow depolarization is still observed in a longtime region and the amplitude of the muon-spin precession is small, suggesting that the long-range AF ordered region is not 100% in the further reduced sample
but coexists with the slowly ﬂuctuating region of Cu
spins. From the analysis of the spectra, it has been
estimated that the volume fraction of a magneticallyordered region is ∼ 25% and the slowly ﬂuctuating region exhibiting the superconductivity is ∼ 75%. These
results suggest that the long-range AF order and superconductivity with a high T c value coexist with eachother in the further reduced sample of PLCCO withx = 0.05. In the ideally reduced sample of x = 0.05,
the AF order would disappear and the superconductivity would appear homogeneously under the development of the Cu-spin correlation, which is probably thecharacteristic of the electron-doped high-T c cuprates.
References
1) O. Matsumoto et al., Physica C 469, 924 (2009).
2) T. Takamatsu et al., Appl. Phys. Express. 5, 073101(2012).
3) T. Adachi et al., J. Phys. Soc. Jpn. 82, 063713 (2013).
4) T. Adachi et al., Condens. Matter 2, 23 (2017).
5) T. Adachi et al., J. Phys. Soc. Jpn. 85, 114716 (2016).

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Reduction in Néel Temperature of La2 CuO4 Nanoparticles
S. Winarsih,∗1,∗2 F. Budiman,∗3,∗4 H. Tanaka,∗3 T. Goto,∗5 T. Adachi,∗5 B. Kurniawan,∗2 B. Soegijono,∗2 andI. Watanabe∗1,∗2
Recent reports on antiferromagnetic nanoparticles focus on the reduction in Néel temperature (TN ), the emergence of superparamagnetic behavior, and the increasein the band gap value.1–3) However, there is no uniﬁed
research on their magnetically ordered state. The causeof TN reduction has also not been investigated. In order to overcome this situation, a study on the magnetic
properties of La2 CuO4 nanoparticles (LCO NPs) using muon spin relaxation (µSR) and NMR is suggested.
La2 CuO4 is a mother compound of high-Tc cuprate oxides that has been well established by experiments andtheoretical methods; thus, a probing nano-sized eﬀect inthis LCO system can be achieved.4)
LCO NPs used in the present study were successfully
obtained through the sol-gel method. A detailed explanation about sample preparation has been reported in
our previous paper.5) Zero-ﬁeld (ZF) µSR on LCO NPs
was carried out at RIKEN-RAL Muon Facility in theUK, using a single pulse positive surface muon beam.
ZF-µSR time spectra of LCO NPs with a particle sizeof 96 nm are shown in Fig. 1. The time spectra wereanalyzed by using Eq. (1). The ﬁrst component represents muon spin precession and the second component
represents the slow relaxation behavior beyond 1 µs. It
is shown that muon spin precession does exist in LCO
NPs and it disappears at 100 K. Muon spin precession
indicates the formation of the long-range ordered (LRO)

Fig. 2. Temperature dependence of the internal field at themuon site in LCO NPs with a particle size of 96 nm.

state.
A(t) = A1 e−λ1 t cos(ωt + ϕ) + A2 e−λ2 t(1)Figure 2 depicts the temperature dependence of theinternal ﬁeld at the muon site, Hint , of LCO NPs witha particle size of 96 nm. It is shown that Hint starts toincrease below ∼ 60 K, indicating that the TN of thissample is ∼ 60 K; this is strongly suppressed comparedto the bulk LCO, which has a TN of ∼ 320 K.4) Hint
reaches a saturated value ≈ 420 G at low temperatures.
This means that LCO NPs have almost the same saturated internal ﬁeld value as that observed in bulk LCO.4)
It is concluded that the nano-sized eﬀect causes the reduction in TN but does not aﬀect the internal ﬁeld at
the muon site. These two phenomena are also observedin a hole- doped La2-x Srx CuO4 bulk system.6) However,
the resistivity of LCO NPs does not show indication ofsuperconducting behavior. The reduction in the TN of
LCO NPs may be owing to the phase separation into
fully antiferromagnetic and paramagnetic regions. Our
139
La NMR results also show that phase separation does
exist in LCO NPs. Further analysis is required to describe this phase separation so that the cause of the reduction in TN of LCO NPs can be clearly explained.
References

Fig. 1. ZF-µSR time spectra of La2 CuO4 NPs with a particle
size of 96 nm.
∗1

∗2
∗3
∗4
∗5

RIKEN Nishina Center
Department of Physics, Universitas Indonesia
Department of Human Intelligence Systems, Kyushu Instituteof Technology
School of Electrical Engineering, Telkom University
Department of Physics, Sophia University

1) X. G. Zheng et al., Phys. Rev. B 72, 014464 (2005).
2) D. Caruntu et al., J. Phys. D, Appl. Phys. 40, 5801
(2007).
3) M. Enhessari et al., Mater. Sci. Semicond. Process 16,
1517 (2013).
4) J. I. Budnick et al., Phys. Lett. A 124, 1 (1987).
5) S. Winarsih et al., Key. Eng. Mater (2019). [in press].
6) E. Stilp et al., Phys. Rev. B 88, 064419 (2013).

- 178 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Muon spin relaxation after hydrogen absorption-desorption
process in Pd
M. Mihara,∗1,∗2 H. Araki,∗3 K. Shimomura,∗2,∗4 W. Higemoto,∗2,∗5 M. Mizuno,∗3 K. Sugita,∗3 Y. Tanaka,∗3
Y. Kitayama,∗3 D. Tomono,∗2,∗6 E. Torikai,∗2,∗7 W. Sato,∗8 K. Ohkubo,∗3 R. Murakami,∗3 N. Matsuoka,∗3
I. Watanabe,∗2 T. Matsuzaki,∗2 and R. Kadono∗2,∗4
Palladium has a unique property as a hydrogen storage material, by which it can absorb large amountsof hydrogen under ambient hydrogen gas pressure orby electrochemical charging at around room temperature.1) By using positron annihilation lifetime spectroscopy, we have found that an anomalously large
amount of vacancies are formed in Pd after a hydrogen absorption-desorption process at room temperature.2,3) In addition, our recent µSR study on Pd has
shown that in electrochemically charged Pd with hydrogen, a β hydride phase (PdHx ) remains even afterhydrogen desorption by degassing at room temperature.4) These results suggest that residual hydrogenatoms are possibly trapped after the desorption process due to the formation of vacancies. Although somemodels have been suggested, such as the formation ofvacancies in a hydride phase2,3) or a vacancy-hydrogen(V-H) cluster5) in metal-hydrogen systems, no direct
evidence to judge those models have been presented
yet. In this report, we present the result of ZF-µSR
measurements on post-annealed PdHx at various temperatures to clarify the microscopic property of residual hydrogen atoms in Pd.
The µSR experiment was performed at the RIKENRAL muon facility and J-PARC. The PdHx samples
were prepared by means of electrolytic charging inwhich a voltage was applied between Pd and Pt plates
immersed in NaCl solutions. In order to minimize thetime between the post-annealing and the µSR measurement, an equipment consisting of an electric furnace and a glass tube connected to a vacuum pump
was prepared beside the µSR experimental port. The
post-annealing was done for 1 h just before the µSR
measurement, and the amount of removed hydrogenby the post-annealing process was deduced from theweight diﬀerence.
The ZF-µSR spectra for each sample were well explained by a combination of a dynamic Gaussian KuboToyabe (DKT) function and a nearly non-relaxing
component.4) Figure 1 shows a typical result of theasymmetry of the relaxing DKT component and the
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

Department of Physics, Osaka University
RIKEN Nishina Center
Division of Materials and Manufacturing Science, Osaka
University
IMSS, KEK
JAEA
RCNP, Osaka University
University of Yamanashi
Kanazawa University- 179 -

Fig. 1. Post-annealing temperature dependence of asymmetry for ZF-µSR in PdHx and hydrogen content.

Fig. 2. Post-annealing temperature dependence of field distribition width for ZF-µSR in PdHx

amount of hydrogen content in Pd as a function of
the post-annealing temperature. This shows that hydrogen in PdHx is stable up to about 100◦ C and ismostly removed at around 200◦ C, and the asymmetry
follows almost the same annealing temperature dependence with the hydrogen content. The values of ﬁeld
distribution width ∆ for the DKT function are nearly
constant and independent of the annealing temperature, as shown in Fig. 2. The present result suggeststhat the residual hydrogen keeps a β hydride phase inwhich hydrogen atoms stay closely together like a cluster at a trap site and are released from Pd once sucha hydrogen cluster is dissociated.
References

1) B. D. Adams, A. Cheni, Materialstoday 14, 282 (2011).
2) K. Sakaki et al., Mat. Trans. 43, 2652 (2002).
3) K. Sakaki et al., J. Alloys Comp. 414, 204 (2006).
4) M. Mihara et al., JPS Conf. Proc. 21, 011031 (2018).
5) Y. Fukai, H. Sugimoto, J. Phys. Condens. Matt. 19,436201 (2007).

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Negative muon spin rotation with low-density gas target undertransverse magnetic field to solve the proton radius puzzle
S. Kanda,∗1 K. Ishida,∗2 M. Iwasaki,∗1,∗2 Y. Ma,∗1,∗2 S. Okada,∗1 and M. Sato∗3
When a negative muon is captured by a nuclear
Coulomb potential, an electron around the nuclei iskicked out and the muon forms an exotic bound state
called muonic atom. Muonic atom provides a unique
opportunity to study the nuclear structure such as the
charge radius of the nuclei. In particular, the proton
charge radius attracts renewed interest since the measurement of the Lamb shift in muonic hydrogen.1) The
experiment derived a signiﬁcantly discrepant result compared to the results of electron-proton scattering andhydrogen spectroscopy. This discrepancy has been an
important unsolved problem in sub-atomic physics.
To obtain a new insight into the puzzle, a new measurement of the ground-state hyperﬁne splitting (HFS)in muonic hydrogen is planned. The experiment aims
to determine the proton Zemach radius, which is deﬁned as a convolution of the electric charge and magnetic
moment distributions. As a preliminary experiment toward the spectroscopy of HFS, a muon spin rotation(µSR) measurement with a gaseous hydrogen target was
proposed.2) The objective of the experiment was to understand the spin depolarization process involving themuonic hydrogen atom.
In a magnetic ﬁeld, muon spin rotates with the Larmor frequency, which depends on the hyperﬁne state ofmuonic atom. Therefore, we can quantify the population of the hyperﬁne states and the depolarization eﬀect
by measuring the angular asymmetry of decay electrons.
Figure 1 illustrates the experimental setup at Port4

Fig. 1. Experimental setup: (a) cross-sectional view; (b)view from downstream. The numbers in the parentheses
denote: (1) negative pulsed muon beam, (2) Helmholtz
coils, (3) aluminium gas chamber, (4) top electron detectors, and (5) bottom electron detectors.
∗1
∗2
∗3

RIKEN Cluster for Pioneering Research
RIKEN Nishina Center
High Energy Accelerator Research Organization (KEK)

Fig. 2. Decay electron time spectrum with deuterium gas
target at 1 atm. No magnetic field was applied. Eachline corresponds to the respective fitting result.

in RIKEN-RAL muon facility. A transverse magnetic
ﬁeld was applied using the coils, which are parts of
the CHRONUS spectrometer. Decay electrons from themuonic atoms were detected by the segmented scintillation counters with silicon photomultiplier (SiPM) readout. The detectors were originally developed for the
muonium production experiment at Port3.3) A study
conducted in 20164) revealed that a countermeasure forthe background arising from the duct-streaming neutrons is essential for suﬃcient signal-to-noise ratio. Accordingly, the detectors were placed away from the beamaxis. The inner walls of the target chamber were covered
with silver plates to reduce the lifetime of wall-stopped
muons via nuclear capture.
The experiment was conducted in 2018 with a gaseous
deuterium target to establish the measurement procedure. Deuterium was selected owing to its longerlifetime of polarization instead of protium. Figure 2
shows a measured time spectrum of electrons from themuon decays. The spectrum was analyzed using a ﬁtting function containing three exponential components
and a constant background. Each exponential component corresponded to the muon lifetime in silver (87 ns),aluminium (864 ns), and deuterium (2195 ns). The
beam momentum was optimized at several target densities considering the muonic hydrogen yield. The analysis
for the µSR measurement under the transverse magnetic
ﬁeld is in progress.
References

1) R. Pohl et al., Nature 466, 213 (2010).
2) S. Kanda et al., J. Phys. Conf. Ser. 1138, 012009 (2018).
3) S. Okada et al., RIKEN Accel. Prog. Rep. 50, 244 (2016).
4) M. Sato et al., RIKEN Accel. Prog. Rep. 51, 228 (2017).

- 180 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 52 (2019)

Measurement of total muonium emission yield from silica aerogel
using µSR method
K. Ishida,∗1 K. Suzuki,∗2 M. Iwasaki,∗1,∗3 S. Kanda,∗3 S. Okada,∗4 T. Mibe,∗5 Y. Oishi,∗6 A. Olin,∗7
S. Kamal,∗8 and J. Brewer∗8
We are working towards the development of producing slow muon beams, as a source of the accelerated
cold muon beam, to be used for the muon g-2/EDM
measurement planned at J-PARC.1) We observed at
TRIUMF that the muonium (Mu = µ+ e− ) emission
rate from silica aerogel to vacuum is enhanced by surface ablation.2,3) By ionizing the muonium with an intense laser, high intensity slow muon source can beobtained. However, the present muonium yield measurement by tracking of the muon decay positron islimited to a region away (∼5 mm) away from the surface owing to the large background from the muoniums
decaying in aerogel, whereas we plan to ionize muoniums in the vacuum region less than 5 mm from thesurface because most of the muoniums emitted are expected to stay there. Although we can extrapolate themeasured muonium yield to the region closer to thesurface with modeling, it is much preferable if we canget the information directly.
We performed a new measurement using a completely diﬀerent method, muonium spin rotation(MuSR) under applied magnetic ﬁeld (∼0.22 mT). The
muonium precession is kept during its diﬀusion in aerogel and even after its emission to vacuum. Here, if
we put a metallic foil such as gold attached to the
aerogel surface, the muonium entering the metal will
become diamagnetic and the muonium precession willstop. This will decrease the precession amplitude withthe time after muon beam injection and can be observed as the relaxation in µSR spectra. For example,
if 10% of the formed muonium has reached the foil by agiven time, the precession amplitude should decrease
to 90%. Thus, the precession spectrum gives us information on the timing distribution of the muoniums
reaching the foil.
We set an aerogel sample with a gold foil stacked
at the downstream surface in the ARGUS µSR spectrometer at the RIKEN-RAL Muon Facility. First,
we set the muon beam momentum to stop the muonsin the middle of the aerogel and measured the intrinsic muonium spin relaxation. The relaxation (0.0389(11) µs−1 ) was subtracted as the background in all thefollowing measurements. Then, we set the momentum
∗1

∗2
∗3
∗4
∗5
∗6
∗7
∗8

RIKEN Nishina Center
Department of Physics, Nagoya University
Meson Science Laboratory, RIKEN
Atomic, Molecular and Optical Physics Laboratory, RIKEN
IPNS, KEK
IMSS, KEKTRIUMF
University of British Columbia- 181 -

Fig. 1. MuSR spectra under 0.22 mT with muons stoppingnear the downstream surface of silica aerogel with thegold foil placed at 0 mm (above) and 20 mm (bottom)
from the surface. The precession signal with approximately 100 times the period of muonium is due to thediamagnetic muons that did not form muonium.

to snsure that the muon stopping distribution peakedat the downstream surface edge of the aerogel, thereby
contributing to the largest muonium emission probability. In this half stopping condition, it is evident thatthe muonium precession relaxes faster, indicating thegradual loss of muoniums due to transfer to the gold
foil. MuSR measurement was also performed for different foil distances (10 and 20 mm) to obtain detailed
timing and space information on muonium distribution
in vacuum.
The MuSR spectra with the gold foil at 0 mm and
20 mm are compared in Fig. 1. The initial muonium
precession amplitude was approximately 2.5% in bothcases and the relaxation rates after subtracting thebackground rate were 0.0355 (20) µs−1 and 0.0146(31) µs−1 , respectively. The result can be understoodby considering the diﬀerent timing distribution of themuoniums reaching the foil. A detailed analysis to extract the muonium emission rate and timing from therelaxation spectra is in progress.
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).

3. Radiochemistry and Nuclear ChemistryⅢ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Extraction behavior of rutherfordium as a cationic fluoride complex
with a TTA chelate extractant from HF/HNO3 acidic solutions†
A. Yokoyama,∗1 Y. Kitayama,∗2 Y. Fukuda,∗2 H. Kikunaga,∗3 M. Murakami,∗4 Y. Komori,∗4 S. Yanou,∗4
H. Haba,∗4 K. Tsukada,∗5 and A. Toyoshima∗5
Rutherfordium (Rf) has atomic number 104 and is
the lightest among the transactinide, or superheavy,
elements. The element is positioned as a homologue ingroup 4 of the Periodic Table of elements, which is predicted to be in the 6d transition series. The chemical
properties of such elements have attracted much attention because of possible deviations from those of theirhomologs as a result of enhancement of the relativistic
eﬀect for heavy elements. It was found diﬃcult thatthe characterization is performed based on one-atomat-a-time chemistry for their low production rates andshort half-lives.
In the present study, we used reversed-phase chromatography with 2-thenoyltriﬂuoroacetone (TTA) asa chelating extractant to clarify the chemical properties of the cationic ﬂuoride complexes of the superheavy element Rf. Unlike previous studies with cationexchange resins, the use of TTA enables preferential
extraction of metal ions in group 4, therefore the speciﬁc complex formation constant of Rf can be determined. The experiments were performed at various
HF/0.01 M HNO3 concentrations, with a newly developed resin containing a solution of TTA in n-octanol.
Fluoride complexation with Rf was investigated by extraction with TTA, which is sensitive to the valenceof the metal complex. The Rf behavior was comparedwith those of Zr and Hf.
In the chromatography experiments with TTA, 222
α-events, including formation of 29 time-correlated
α-particle pairs (8.00–8.40 MeV) from 261 Rf and its
daughter nuclide 257 No, were observed in 1771 cycles.
The %ads values for Rf were constant at around 60%
in the [F− ]eq range up to 5 × 10−4 M and then steeply
decreased at [F− ]eq = 9 × 10−4 M. In contrast, thevalue for Hf decreased signiﬁcantly from 100% to afew percent at around [F− ]eq = 1 × 10−4 M. This
is in good agreement with the results of the Zr andHf experiments. This suggests that the cationic ﬂuoride complexes of Rf are more stable than those of
Hf at [F− ]eq > 1 × 10−4 M. Diﬀerences among ﬂuoride species formation with Rf and its homologs are
†

∗1
∗2
∗3
∗4
∗5

Condensed from Radiochim. Acta 107 (1), 27 (2019)
Institute and College of Science and Engineering, Kanazawa
University
Graduate School of Natural Science and Technology,
Kanazawa University
Research Center for Electron Photon Science, Tohoku University
RIKEN Nishina Center
Advanced Science Research Center, Japan Atomic Energy
Agency- 183 -

therefore clearly observed in these [F− ]eq ranges.
Decay of No was taken into account in correction of
the %ads values. The %ads values for 255 No as a function of [F− ]eq in the range 1.93×10−5 to 1.66×10−3 M
were obtained in the study. In the Rf experiments, the%ads values for 261 Rf were constant, at around 60%,in the [F− ]eq range up to 5 × 10−4 M and then steeply
decreased at [F− ]eq = 9 × 10−4 M. In contrast, in the
No experiments, the %ads values for 255 No were lessthan 10% across the entire range of [F− ]eq . The results of the present work conﬁrm that No is adsorbed
on TTA to a small extent and the eﬀect on the %ads
values of 261 Rf is negligible.
The obtained K d values for Rf are compared withthose for Zr and Hf from the independent experimentsin the present study. The result shows signiﬁcant differences between the behavior of Rf and those of its
homologs. The K d values for Rf appear at higher F−
concentrations than those for Zr and Hf. Assumingthat during extraction Rf forms species with TTA, similarly to the other elements in group 4, the decrease in
extraction may be caused by additional cationic ﬂuoride complexation. The K d results show that the
cationic complex of Rf, [RfF]3+ , is more stable thanthose of the other elements at high ﬂuoride concentrations. This stability means that ﬂuoride complexation
with the extracted Rf species is weaker than in thecases of the other elements. This conclusion is consistent with the experimental results obtained with acation-exchange resin.
In conclusion, the adsorption behaviors of Rf, Zr,
and Hf with a TTA extractant were observed in dilute solutions of HF and HNO3 . The behaviors of
the No atoms produced in the decay of Rf were determined with 255 No nuclides produced in runs otherthan the Rf experiments to assess the precise behavior of Rf, without the eﬀects of its daughters. The
results of the present study suggest that the chemical
species involved in TTA extraction may be [RfF]3+ ,based on comparisons with the results for Zr and Hf.
It was concluded that ﬂuoride complexation with Rf
cations is weaker than that with either Zr or Hf, which
are group 4 homologs. The observed behavior of Rf is
supported by theoretical calculations and agrees withthe results of previous experiment on cation exchange.
This study is the ﬁrst comparison of complexation data
for Rf cations with those for Zr and Hf, other thanthose based on cation-exchange experiments.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Coprecipitation experiment of element 102, No, with Sm(OH)3
using NH3 and NaOH solution
H. Ninomiya,∗1 Y. Kasamatsu,∗1 S. Hayami,∗2 M. Nagase,∗2 Y. Shigekawa,∗1 N. Kondo,∗1 E. Watanabe,∗1
H. Haba,∗3 T. Yokokita,∗3 Y. Komori,∗3 D. Mori,∗3 Y. Wang,∗3 K. Ghosh,∗3 N. Sato,∗3 and A. Shinohara∗1

∗1
∗2
∗3

20
214

Po

CountsHeavy elements are expected to have the characteristic chemical properties in the periodic table owing
to signiﬁcant relativistic eﬀects on their orbital electrons. From the previous cation-exchange studies on
element 102, noberium (No) in HCl, the most stable
ion valency of No in aqueous solution is reported to
be +2, although that of other heavy actinide elements
is +3.1,2) However, it is diﬃcult to investigate thechemical behavior of heavy elements. Heavy elementswith Z ≥ 101 are synthesized by heavy-ion-induced
nuclear reactions with very low production rates andtheir half-lives are short.3) Thus, the chemical experiments of these elements must be rapidly conducted on
one-atom-at-a-time basis using nuclear reaction products transported from the target chamber by a He/KCl
gas-jet system. Additionally, for unambiguous identiﬁcation of a single atom, detection of α particle isrequired. Owing to these diﬃculties, there are a few
reports on solution chemical experiments of No. In thetri-n-octylamine chloride extraction system and cationexchange experiment in HCl, the elution behavior of
No was reported to be similar to that of alkaline earth
metals.4) To deepen the understanding of the chemical
properties of No, we aim at investigating a precipitation of nobelium hydroxide.
In previous studies, we newly developed coprecipitation method with samarium hydroxide to investigate
the hydroxide and ammine complexation properties ofheavy elements.5) Then, we succeeded in conducting
the coprecipitation experiment of element 104, Rf, in
NH3 and NaOH solutions using the developed suction
ﬁltration apparatus. In this study, by applying the coprecipitation method, we performed online coprecipitation experiment of 255 No to investigate the precipitation behavior of nobelium hydroxide.
We produced 255 No (T1/2 = 186 s) and 162 Yb(T1/2 = 18.9 min) by 248 Cm(12 C, 5n)255 No andnat
Gd(12 C, xn)162 Yb reactions with AVF cyclotron at
RIKEN. The reaction products were transported by
the He/KCl gas-jet system to the chemistry room anddissolved in dilute HCl solution. In the case of making
precipitated sample, 20 µg of Sm and 2 mL of the basic
solution (dilute or concentrated aqueous NH3 or 0.10
or 1.0 M NaOH solution) was added into the dissolved
solution in the PP beaker and stirred for 5 min at room
temperature. Then, the solution containing the precipitate was ﬁltrated using the suction ﬁltration apparaGraduate School of Science, Osaka University
Faculty of Science, Osaka University
RIKEN Nishina Center- 184 -

10

255

No

0
7000

7500
8000
Energy / keV

8500

Fig. 1. α-spectra for 255 No standard samples.

tus controlled by PC. In the case of making standard
sample, the reaction products were dissolved in dilute
HCl solution and the solution was put on a Ta plate.
Then, these precipitated and standard samples weredried and subjected to alpha particle measurement by
the automated rapid α/SF detection system. After alpha particle measurement, γ-ray activities of 162 Yb inthe samples were measured with Ge detectors.
We successfully prepared 51 coprecipitated samples
and 48 standard samples. In the alpha-particle measurement (Fig. 1), we detected 243 events for 255 No.
The cross-section of 255 No was estimated to be approximately 450 nb and the value was consistent with thatobtained in the previous report.6) High precipitation
yields of No were obtained and the detailed evaluation
is now under analysis.
In future, we will discuss the hydroxide complexation properties of 255 No based on the comparison of
the coprecipitation behavior of 255 No with those of alkaline earth metal elements.
References
1) J. Maly, T. Sikkeland, R. Silva, A. Ghiorso, Science 160,
1114–1115 (1963).
2) G. T. Seaborg, in The Transuranium Elements,(McGraw-Hill, New York, 1949).
3) M. Schädel, Radiochim. Acta 100, 579 (2012).
4) R. J. Silva, W. J. Mcdowell, O. L. Keller, et al., J. Inorg.
Nucl. Chem. 38, 1207–1210 (1976).
5) Y. Kasamatsu, et al., Appl. Radiat. Isot. 118, 105–116(2016).
6) T. Sikkeland, A. Ghirso, M. J. Nurmia, Phy. Rev. 172,
1232–1238 (1968).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Complex formation of Fr with crown ethers
Y. Komori,∗1 H. Haba,∗1 T. Yokokita,∗1 S. Yano,∗1 N. Sato,∗1 K. Ghosh,∗1 Y. Sakemi,∗2 and H. Kawamura∗3

∗1
∗2
∗3

RIKEN Nishina Center
Center for Nuclear Study, the University of Tokyo
Frontier Research Institute for Interdisciplinary Sciences, Tohoku University

10
18C6

0.5 M 18C6
0.01 M 18C6

1

D

Francium (Fr) is the heaviest known alkali metal withatomic number 87. It is one of the least-studied elements among the naturally occurring elements because
all its isotopes are short-lived. The half-life of its longestlived isotope, 223 Fr, is only T1/2 = 21.8 min. Owing
to experimental diﬃculties, the chemical properties of
Fr have not been studied in detail so far. We aim toclarify the chemical bonding nature of Fr, which is inﬂuenced by relativistic eﬀects, through complex formation studies of Fr. Recently, Haverlock et al. examined the complex formation of Fr+ with calix[4]arenebis(benzocrown-6) (BC6B).1) They reported that Fr+ ismore eﬀectively extracted with BC6B than Cs+ . However, the reason for the selectivity is still unclear. In
this work, we studied the complex formation of Fr using
seven types of crown ethers: 18-crown 6-ether (18C6),
dicyclohexano-18-crown 6-ether (DC18C6), dibenzo-18crown 6-ether (DB18C6), 24-crown 8-ether (24C8),
dibenzo-24-crown 8-ether (DB24C8), 21-crown 7-ether(21C7), and dibenzo-21-crown 7-ether (DB21C7). Complex formation stability and selectivity of alkali metals
with the crown ethers depend on the ring cavity size andsubstituent groups of the crown ethers. Therefore, inthis work, we will investigate the eﬀects of the cavity
size and substituent groups of the crown ethers on thestability and selectivity of the complex formation of Fr.
We produced the second longest-lived isotope of Fr,
212
Fr (T1/2 = 20 min), in the 206 Pb(11 B, 5n)212 Fr reaction. Four sets of an 864-µg/cm2 206 Pb target on a 10 µm
Be foil were placed in a 12 mm spacing in 129-kPa He.
They were irradiated with a 11 B beam at an energy of
86 MeV. The beam energies on the four 206 Pb targets
are calculated to be in the range of 70–79 MeV, which
covers the peak region of the excitation function of the206
Pb(11 B, 5n)212 Fr reaction.2) The 212 Fr atoms that recoiled out of the 206 Pb target were thermalized in He
gas, attached to KCl aerosol particles, and transported
through a Teﬂon capillary to a chemistry laboratory. In
the chemistry laboratory, the aerosols were collected ona piece of Naﬂon sheet for 20 s. The aerosols were dissolved with 100 µL of 1 M nitric acid and transferred
into a polypropylene (PP) tube. Another 600 µL of 1 M
HNO3 and 700 µL of nitrobenzene containing each of thecrown ethers were then added into the PP tube. The PP
tube was shaken for a certain time for extraction. Aftercentrifuging the PP tube for 2 min, 500 µL of each phase
was subjected to γ-ray spectrometry to determine the
distribution ratios (D) of Fr. The D values were measured as functions of the shaking time and the concentration of each crown ether. These results were comparedwith those of RIs of lighter alkali metals such as 24 Na,
43
K, and 137 Cs.

0.1

0.01

100 200 300 400 500 600 700

Fig. 1. Variations of D values of Fr+ as a function of shaking
time in solvent extraction with 0.01 and 0.5 M 18C6.

Figure 1 shows the variation of the D values of Fr+ as
a function of the shaking time in the solvent extraction
with 0.01 and 0.5 M 18C6. We found that the extraction
equilibrium time of Fr+ is as fast as within 30 s. Therefore, we ﬁxed the shaking time to be 3 min. The 18membered rings, with a cavity diameter of 2.6–3.2 Å,3)
show the highest aﬃnity for K+ because their cavity sizes
ﬁt the size of K+ ion (ionic diameter: 2.66 Å4) ). The cavity diameter of the 24-membered crowns is in the rangeof 4.5–5.0 Å,5) which is larger than all alkali metal ions.
Thus, they show aﬃnity for larger alkali metal ions suchas Cs+ (3.34 Å4) ) and Fr+ (3.46 Å6) ). The cavity diameter of 21-membered crowns is in the range of 3.4–4.3 Å.3)
When using DB21C7, the D values of Cs+ are slightly
larger than those of Fr+ , while the D values of Cs+ andFr+ are almost the same when using 21C7. Two benzene
rings of DB21C7 may aﬀect the selectivity between Cs+
and Fr+ .
In this work, the D values of Fr+ with several types ofcrown ethers are almost the same as those of Cs+ , which
can be qualitatively understood by the relation between
the size of the alkali metal ions and the ring cavity diameter of the crown ethers. However, in the previous
study using calixarene, the D values of Fr+ are almost
one order of magnitude higher than those of Cs+ .1) To interpret these results and elucidate the reason of complex
formation selectivity between Fr+ and Cs+ , we will perform further investigations, for example, XAFS studiesof the Cs+ -crown ether and Cs+ -calixarene complexes,
and quantum chemistry calculations for Fr+ as well as
Cs+ .
References

1) T. J. Haverlock et al., J. Am. Chem. Soc. 125, 1126 (2003).
2) Y. Komori et al., RIKEN Accel. Prog. Rep. 51, 224 (2018).
3) C. J. Pedersen, J. Am. Chem. Soc. 92, 386 (1970).
4) L. H. Ahrens, Geochim. Cosmochim. Acta 2, 155 (1952).
5) M. Chamsaz, Russ. J. Inorg. Chem. 50, 413 (2005).
6) L. H. Delmau et al., J. Phys. Chem. B 117, 9258 (2013).

- 185 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Anion and cation exchange of Pa in HF/HCl mixture solution for Db
chemistry
T. Yokokita∗1 and H. Haba∗1
Clarifying the chemical properties of superheavy elements with atomic number Z ≥ 104 is an intriguing andimportant subject. These elements are produced at accelerators using heavy-ion-induced nuclear reactions. The
production rates of these elements are low, and their halflives are short (T1/2 ≤ 1 min). Thus, chemical studies onthese elements are conducted on a single-atom basis.1)
F− ion is a very strong complexing agent for thegroup-5 elements (Nb and Ta). The ﬂuoride complex
species of the heaviest group-5 element, dubnium (Db),
is very interesting (Db forms [DbOFx ]n− or [DbFx ]n− )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 the ﬂuoride complex species of Db, we plan to perform an ionexchange study of Db. In this study, we performed anionand cation-exchange experiments of Pa (pseudo homologue of Db) in HF/HCl mixture solution to determine thesuitable experimental condition of Db and obtain comparable data for Db.
233
Pa was obtained as an α-decay daughter of 237 Np
in the following procedure. First, 237 Np in 9 M HCl containing 233 Pa was fed onto the TK400 resin’s (TRISKEM)
column. 237 Np was then eluted with 9 M HCl and 233 Pa
was adsorbed on the resin. The adsorbed 233 Pa species
was eluted with 1 M HCl. The eluent containing the Pa
tracers was evaporated and dissolved in 9 M HCl. Then,
Pa nuclide was puriﬁed by anion-exchange column chromatography using a procedure found in Ref. 3).
In the anion-exchange experiments, the anion-exchange
resin (MCI GEL CA08Y) was added in 0.25 mL of
HF/HCl mixture solution containing 233 Pa in a PP tube
and the mixture was shaken using a mixer. Next, theresin was removed by centrifugation. Subsequently, theﬁltrate was pipetted into another tube, weighed, and subjected to γ-ray spectrometry using a Ge detector. The
concentration of HF and HCl was determined by titration with standardized NaOH solution before the experiments. In all anion-exchange experiments, control exper-

Fig. 1. Kd values of Pa in anion exchange as a function of Cl−
concentration.
∗1

RIKEN Nishina Center

Fig. 2. Kd values of Pa in cation exchange as a function of
H+ concentration.

iments without the resin were performed. We also performed cation-exchange experiments of Pa using a cationexchange resin (MCI GEL CK08Y). The experimental
procedures were the same as the anion-exchange experiments. The Kd values were determined from the following
equation:(1)
Kd = Ar Vs /As wr = (Ac − As )Vs /As wr

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 Pa as a function of Cl− concentrationin the anion-exchange experiment are shown in Fig. 1. Inanion exchange, the Kd values of Pa linearly decrease withincreasing concentration of Cl− in [F− ] = 10−6 − 10−2 M.
These results indicate that Pa forms anionic complexes
in the studied conditions. The slope values between log
Kd and log[Cl− ] are −1.4, −1.9, −1.6, −1.9, and −1.2
in [F− ] = 10−6 , 10−5 , 10−4 , 10−3 , and 10−2 M, respectively. These results indicated that the net charge of theadsorbed Pa species are −2 and −1.
The Kd values of Pa as a function of H+ concentrationin the cation-exchange experiment are shown in Fig. 2.
The Kd values of Pa were > 103 mL g−1 and Pa was adsorbed on the resin in [F− ] = 10− 7 − 10− 5 M and [H+ ]= 0.01 M. These results indicate that Pa forms cationicspecies in these F− concentrations. The linear relation
between log Kd and log [H+ ] is not obtained. It is suggested that some cationic Pa species coexist and/or Pa
forms chloride complexes.
Recently, we produced 95 Nb and 179 Ta (homologues ofDb) in the nat Zr(d, xn)95 Nb and nat Hf(d, xn)179 Ta reactions, respectively. We plan to study anion- and cationexchange behavior of Nb and Ta in HF/HCl using thesetracers for Db chemistry.
References

1) 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).

- 186 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Study of anion exchange equilibrium of Zr and Hf in H2 SO4 for Rf
experiment
T. Yokokita,∗1 Y. Kasamatsu,∗2 Y. Komori,∗1 E. Watanabe,∗2 K. Ghosh,∗1 Y. Wang,∗1 D. Mori,∗1 A. Shinohara,∗2
and H. Haba∗1
Clarifying the chemical properties of superheavy elements with atomic number Z ≥ 104 is an intriguing andimportant subject. These elements are produced by accelerators using heavy-ion-induced nuclear reactions. The
production rates of these elements are low, and their halflives are short (T1/2 ≤ 1 min). Therefore, chemical studies on these elements are conducted on a single-atom basis.1)
The chemical properties of superheavy elements havebeen discussed by comparing their chemical behavior withthat of lighter homologous elements. The solution chemistry of superheavy elements has been studied mainly forelement 104, Rf. In these studies, experiments on Rf andhomologous elements was carried out under the same conditions, but even for homologous elements, equilibrated
data were obtained only under a few conditions. In particular, it was reported that the chemical reaction kinetics between Zr and Hf are diﬀerent in H2 SO4 .2) Equilibrated data are necessary to discuss chemical properties
such as complex formation. Therefore, the observation ofequilibration and the equilibrated distribution data arevery important to characterize the sulfate complex formation of Rf. In our previous study, we performed anionexchange experiment with 88 Zr, 175 Hf, and 234 Th and determined the suitable experimental condition for Rf.3) In
this work, we performed online anion-exchange experiments with Zr and Hf by using AMBER4) as the modelexperiment of Rf.
85
Zr and 169 Hf were produced in the nat Ge(18 O,
85xn) Zr and nat Gd(18 O, xn)169 Hf reactions, respectively,
using the K70 AVF cyclotron at RIKEN. The nuclear reaction products were transported using a gas-jet system
to the chemistry laboratory and deposited on the collection site of AMBER for 60 s. Then, the deposited sample
was dissolved in 0.21–0.27 mL of 0.16–0.72 M H2 SO4 . The
solution sample entered the chemical reaction container
containing the anion-exchange resin (MCI GEL CA08Y).
After shaking the container with a vortex mixer for 10–
600 s, only the solution phase was pushed out of the container by using compressed air, and was assayed by γ-ray
spectroscopy. The residual Zr and Hf species adsorbedon the resin were stripped by washing the resin ﬁve times
with 0.25 mL of 1 M H2 SO4 . Subsequently, the resin wasconditioned with H2 SO4 for the next anion exchange. A
control experiment was also performed without the resin
to determine the radioactivity of the control solution. The
Qd values were determined from the following equation:
Qd = Ar Vs /As wr = (Ac − As )Vs /As wr(1)

where Ar , As , and Ac are radioactivities of the resin, thesolution, and the control solution, respectively; Vs is thevolume (mL) of the solution; and wr is the mass of thedry resin (g).
∗1
∗2

RIKEN Nishina Center
Graduate School of Science, Osaka University

Fig. 1. The Qd values of (a) Hf and (b) Zr in anion exchange
as a function of shaking time.

The activity of 85 Zr was very low, and the Qd valuesof Zr had large errors. Figures 1(a) and 1(b) show thetime dependence of the Qd values of Hf and Zr, respectively. The Qd values of Hf are constant within the errors
in the entire time range studied in 0.26–0.72 M H2 SO4 .
In 0.16 M H2 SO4 , the Qd values of Hf become constantwithin the errors after 180 s. From the time when the Qdvalues became constant within error, the anion-exchange
reaction reaches equilibrium within 180 and 10 s in 0.16
and ≥ 0.26 M H2 SO4 , respectively. From these results, it
is seen that the anion-exchange reaction kinetics is slow
in low concentration of H2 SO4 . It is suggested that theanion-exchange kinetics of Rf may be slow in low concentration of H2 SO4 . In the case of Zr, the Qd values areconstant within the error in the entire time range studied
in 0.16–0.72 M H2 SO4 . However, from this result, the discussion of anion-exchange reaction equilibrium for Zr isdiﬃcult, because the obtained Qd values have large error.
In any case, we need to perform experiments with Zr
again using enough activity of Zr isotopes. To obtain thesmall variations’ Qd values of small variations, we need tosuitably adjust the ratio of Wr and Vs , when we performthe control experiment. For Hf, the Qd values in 0.51
and 0.72 M H2 SO4 have large errors; therefore, we planto perform experiments under this condition again using
increased resin weight.
References

1) A. Türler, V. Pershina, Chem. Rev. 113, 1273 (2013).
2) Z. J. Li et al., Radiochim. Acta 100, 157 (2012).
3) Y. Kasamatsu et al., Radiochim. Acta 103, 513 (2015).
4) T. Yokokita et al., RIKEN Accel. Prog. Rep. 51, 217 (2018).

- 187 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Development of 211 At-labeled antibody for targeted alpha therapy

Radiotherapeutic agents labeled with various αemitting nuclides have been developed for targeted alpha therapy. 211 At has a simple decay scheme and can
avoid the risk of side eﬀects caused by daughter nuclides; it is thus considered a useful α-emitter for thistherapy. Given the requirements for 211 At-labeled pharmaceuticals in the future, RIKEN Nishina Center for
Accelerator-Based Science aims to increase the 211 At
production scale a global maximum; this prompted us
to develop 211 At-labeled drugs and labeling methods.
For the attachment of 211 At, organotin compounds
are the most widely used precursor owing to the weakness of the carbon-tin bond, which enables the useof a tin group as a leaving group.1) In this study,
we used an organotin compound, N -succinimidyl-3(trimethylstannyl)benzoate (m-MeATE), for 211 At labeling. According to the direct astatination procedurereported by Lindegren et al.,2) m-MeATE was ﬁrst conjugated with a monoclonal IgG. Then, m-MeATE andIgG were mixed at a molar ratio of 20:1 and incubatedfor 30 min at 25◦ C in a pH-8.5 NaCO3 buﬀer. The
attachment of 211 At was carried out by a modiﬁed protocol of the method of Li et al.3) An oxidizing agent
N-chlorosuccinimide (NCS) (0.2 mg/ml) was added to
the 211 At solution in 1% acetic acid MeOH. Then an
IgG/m-MeATE conjugate in a 0.2 M sodium acetate
buﬀer was mixed with the activated 211 At solution, withthe ﬁnal MeOH and NCS concentrations being 11% and3.6 µg/ml, respectively. The incubation was performedfor 3 min. N -iodosuccinimide (0.2 mg/ml) was thenadded at a ﬁnal concentration of 5.4 µg/ml, and thereaction mixture was incubated for another 1 min. For
puriﬁcation, an Amicon Ultra 50 kDa column (Merck)
was used in ultraﬁltration.
Finally, 5.6 MBq of 211 At-labeled IgG was obtainedusing 40 MBq of 211 At-MeOH (shown in Table 1). In
this experiment, we did not reach the labeling yield that
Li et al. reported previously (40.2 ± 6.9%).3) Further,
we examined the use of a PD Spintrap G-25 gel ﬁltration column for puriﬁcation, only to reduce the yield.
To demonstrate the usefulness of the 211 At-labeled
IgG, we performed a biodistribution study using themice with xenografted tumors speciﬁc to IgG. Threeand 24 h after the 211 At-labeled IgG i.v. injections, themice were dissected to measure tissue radioactivity. As
a control group, free 211 At was also administered. The
results are shown in Fig. 1. Unexpectedly, the distribution of 211 At-labeled IgG was almost the same as that of
∗1
∗2
∗3
∗4

Uptake rates [% ID/g]

Y. Kanayama,∗1 K. Sakamoto,∗2 E. Ebisui,∗3 Y. Wang,∗4 T. Yokokita,∗4 Y. Komori,∗4 D. Mori,∗4 H. Haba,∗4 andY. Watanabe∗1

Laboratory for Pathophysiological and Health Science,
RIKEN
Laboratory for Nonnatural Amino Acid Technology, RIKEN
Liver Cancer Prevention Research Unit, RIKEN
RIKEN Nishina Center- 188 -

30

Free 211At 3h

25

211At-IgG 3h

20
15Free 211At 24h
211At-IgG 24h

1050

Fig. 1. Biodistribution of free 211 At and 211 At-labeled antibody 3 and 24 h after i.v. injection in the tumor-bearing
mice.
Table 1. Labeling results of 211 At-labeled IgG purified byultrafiltration or gel filtration.
Purification
methodRadioactivity
yield [%]

Protein yield[%]

Specific activity[kBq/ug]

Ultrafiltration

13.9

75.0

12.9

Gel filtration

5.0

69.5

14.9

Table 2. Labeling results of 211 At-labeled IgG or IgG/mMeATE purified by reduced nonspecific binding gel.
Precursor

Radioactivity
yield [%]

Protein yield[%]

Specific Activity[kBq/ug]

IgG/m-MeATE

43.9

85.6

31.6

Intact IgG

12.9

79.3

12.5

free 211 At. The high accumulation rates in the stomach
and thyroid indicated the physiological accumulation of211
At detached from IgG.
From these results, we speculated that the increasedhydrophobicity by astatination may have caused thenonspeciﬁc binding of 211 At-labeled IgG to column ﬁlters or gels in the puriﬁcation step, resulting in a low
radioactivity yield despite a high protein yield. To overcome this problem, we used a specialized gel to alleviate
nonspeciﬁc binding. As shown in Table 2, the radioactivity yields were signiﬁcantly improved.
In the next step, we will examine a labeling method
using decaborane, which is expected to have a higher
stability in bonding with 211 At in the body.
References
1) F. Guerard et al., Cancer Biother. Radiopharm. 28, 1(2013).
2) S. Lindegren et al., J. Nucl. Med. 49, 1537 (2008).
3) H. K. Li et al., Cancer Sci. 108, 1648 (2017).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

RI imaging tracers for Na+ /K+ dynamics in a living body
S. Motomura,∗1 I. Kii,∗2 H. Haba,∗3 H. Yakushiji,∗1 Y. Watanabe,∗1 and S. Enomoto∗4
Sodium (Na) and potassium (K) are essential metalelements that play important roles in our body. Bothmetal elements exist as ions in the body and each constitutes approximately 0.2% of the body weight. Although they both are alkali metals located in group 1of the periodic table of elements, the ions Na+ and K+
behave very diﬀerently in a living body. For example,
the concentration of Na+ is higher in the extracellular
ﬂuid than that in the intracellular ﬂuid, while the concentration of K+ is conversely higher in the cell thanthat in the extracellular ﬂuid.
The diﬀerent behaviors of Na+ and K+ are caused
by certain functions of some biomolecules that can signiﬁcantly distinguish the ions. An example of suchmolecule is Na+ /K+ -ATPase, which takes in two K+
ions into a cell and takes out three Na+ ions out of acell in one cycle. This mechanism is used to form themembrane potential in neurons, reabsorption of Na+ions in kidneys, etc.
The idea of the MetalloDiagnosis is to obtain the
diagnostic information of molecular functions by observing the behavior of associated metal elements(Fig. 1). Various metal elements are controlled bysome biomolecules in a living body. Thus, the behaviorof the metal elements can be altered corresponding towhether the molecule is functioning normally or not. If
we can non-invasively visualize the diﬀerent behaviorof the associated metal elements, we can make noninvasive imaging diagnosis of the molecular functions.
We are trying to use our imaging apparatus called
GREI1) to realize the MetalloDiagnosis. The GREI isa kind of gamma-ray imaging camera with an imaging
principle called the Compton camera made of germanium semiconductor radiation detectors. The GREI
can take three-dimensional images of radio-tracers injected into living animals even by using a single GREI
imaging head without any rotation or movement.2)
Furthermore, the GREI can identify each radioisotope
injected simultaneously into an animal by distinguishing the gamma-ray energy in the energy range from100 keV to 2 MeV, owning to the excellent energy resolution of the semiconductor detectors.
To realize the MealloDiagnosis by GREI, we needto prepare radioisotopes of each metal element that
we are going to take images of the behavior in a living body. For the MetalloDiagnosis of Na and K, wechose 24 Na, 42 K, and 43 K that have the half-lives of
15-, 12-, and 22-hours, respectively (Table 1). We es∗1

∗2
∗3
∗4

RIKEN Center for Biosystems Dynamics ResearchCompass to Healthy Life Research Complex Program,
RIKEN
RIKEN Nishina Center
RIKEN Center for Life Science Technologies- 189 -

Fig. 1. Concept of MetalloDiagnosis by GREI. Diagnostic information is obtained by observing the associatedmetals.
Table 1. Radioisotopes of Na and K for GREI imaging.

Nuclide24

Half life

Gamma-ray energy (keV)Na

15.0 h

1368.6, 2754.0

4212.4 h1524.743

22.3 h372.8, 617.5

KK

tablished the preparation schemes for these radioisotopes utilizing the nuclear reactions of nat Mg(d, x)24 Na
and nat Ca(d, x)42, 43 K. We have also established a delivery scheme for these radioisotopes from Wako to themolecular imaging facility in the RIKEN Kobe campus. It should be noted that we have made delivery of
24
Na, 42 K, and 43 K radioisotopes 6 times in FY2018.
In the RIKEN Kobe campus, it was the ﬁrst timethat we have used the radioisotopes of 24 Na, 42 K, and43
K for experiment. We have started GREI imaging experiment of living mice injected the Na and K
radioisotopes simultaneously. For each GREI experiment, approximately 1 MBq and 100 kBq of 24 Na and43
K, respectively, were used for the time-course imaging of Na+ /K+ dynamics in a living mouse, and it waspossible to visualize the diﬀerent behavior of Na+ andK+ . This study is ongoing and the results are being
prepared to consider for publication.
References
1) S. Motomura et al., J. Anal. At. Spectrom. 28, 934(2013).
2) T. Ida, S. Motomura et al., Jpn. J. Appl. Phys. 58,
016002 (2019).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Measurement of activation cross sections of alpha particle induced
reactions on iridium up to an energy of 50 MeV†
S. Takács,∗1 F. Ditrói,∗1 Z. Szücs,∗1 M. Aikawa,∗2 H. Haba,∗3 Y. Komori,∗3 and M. Saito∗4
195m

Pt has proper decay characteristics for internal therapy investigations (T1/2 = 4.03 d, IT = 100%,Eγ = 98.9 keV, and Iγ = 11.4%). This isomeric statetransfers its energy by internal transition and emits
low energy gamma photons, conversion electrons, andAuger electrons with high intensity. Owing to the low
energy of the emitted conversion and Auger electrons,
their energy is deposited in a very short range andthen, most parts of the deposited energy get concentrated in a small volume, preferably in a single targeted
cell. In addition, its low energy gamma photons canbe used for imaging. 195m Pt can be attached to platinum complexes, which are used for chemotherapy, andthus, it can be applied as an eﬀective anti-tumor agent
in radiotherapy.
The 195m Pt for medical applications is produced inreactors in the 194 Pt(n, γ)195m Pt reaction with a moderate yield and low speciﬁc activity. Charged particle
induced reactions may provide high speciﬁc activity
isotopes. Several production routes to produce 195m Pt
were investigated previously but the nat Ir(α, x)195m Pt
reaction was not studied. The high spin isomeric state(13/2+ ) of 195 Pt can be formed in a reaction with particles capable to transfer high angular momentum. Thus
alpha particle bombardment is one of the best ways to
produce this radionuclide.
We measured the cross sections of alpha particle
induced nuclear reactions on natural iridium using a51.2-MeV alpha particle beam. The standard stackedfoil target technique and activation method were applied. The activity of the reaction products was assessed without chemical separation using high resolution gamma spectrometry based on a HPGe detector(ORTEC GEM-25185-P).
Two stacks containing Ir target and Ti monitor foils
were irradiated at the AVF cyclotron in the RIKEN
RI Beam Factory, Wako, Japan, in a Faraday-cup-likevacuum chamber equipped with a long collimator, assuring a small solid angle for the escaping secondary
electrons. The initial beam energy was conﬁrmed by
the measurement of time of ﬂight before and after theirradiation.1) The beam current was kept constant during the irradiation. The beam parameters were also
monitored by the nat Ti(α, x)51 Cr monitor reaction.
†
∗1
∗2
∗3
∗4

Condensed from the article in Appl. Radiat. Isot. 136, 133(2018)
Institute for Nuclear Research, Hungarian Academy of Sciences
Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University- 190 -

Fig. 1. Cross sections of nat Ir(α, x)195m Pt reaction in comparison with the predicted data calculated by the
TALYS nuclear model code system.2)

Excitation functions for the production of 196m2 Au,
Au, 195m,g Au, 194 Au, 193m,g Au, 192 Au, 191m,g Au,
191
Pt, 195m Pt, 194g Ir, 194m Ir, 192g Ir, 190g Ir, and 189 Ir
isotopes were determined up to 50 MeV alpha particle
energy on natural iridium target. The measured data
were compared to the available experimental data andresults of theoretical calculations.2) Figure 1 shows theexcitation function for the nat Ir(α, x)195m Pt reaction.
The nat Ir(α, x)195m Pt production route utilizes thenatural iridium target and provides high speciﬁc activity of 195m Pt. The radio-purity of 195m Pt producedby cyclotrons on iridium targets is somewhat lower
than the reactor produced 195m Pt due to the unavoidable co-produced 193 Pt and 191 Pt radionuclides but theamount of these two isotopes can be reduced by using the enriched 193 Ir target material, and at the sametime, the amount of 195m Pt can be increased. Irradiating an 193 Ir target enriched to 95% with alpha particles
of an energy of 50 MeV and beam intensity of 200 µA
for 24 h, activity of about 1 GBq of 195m Pt can beachieved at the end of the bombardment.
Besides the excitation function of the nat Ir(α, x)195m Pt
reaction, we measured the cross-section data for the
production of 196m2 Au, 196m,g Au, 191 Pt, 194g Ir, 194m Ir,
190g
Ir, and 189 Ir isotopes for the ﬁrst time. The measured cross sections may also contribute to the improvement of theoretical model codes.
196m,gReferences
1) T. Watanabe, et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566, (2014).
2) A. J. Koning, D. Rochman, Nucl. Data Sheets 113, 2841
(2012).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Cross-section measurement of α-induced reactions on nat Er for 169 Yb
production
M. Saito,∗1,∗2 M. Aikawa,∗1,∗2,∗3 M. Sakaguchi,∗4,∗2 N. Ukon,∗5,∗2 Y. Komori,∗2 and H. Haba∗2

∗1
∗2
∗3
∗4
∗5

Graduate School of Biomedical Science and engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
School of Science, Hokkaido University
Advanced Clinical Research Center, Fukushima Medical
University- 191 -

600

nat

This work
B. Kiraly (2008)
A. A. Sonzogni (1992)
A. Archenti (1985)
Y. Homma (1980)
TENDL-2017

169

Er(α,x)

Yb

500
Cross section (mb)Radioisotopes (RIs) are widely used in the medicalﬁelds such as therapy and diagnosis. To develop such
medical treatments, the candidates of medical RIs need
to be studied further. Ytterbium-169 (169 Yb) is a typeof RI that has a half-life of 32.018 days and emits Auger
electrons, X and γ rays. The Auger electrons and X
rays can be used in brachytherapy as an alternative
RI to 125 I and 192 Ir.1) The γ rays at 177.21 keV (Iγ= 22.28%) and 197.96 keV (Iγ = 35.93%) provide theopportunity for diagnosis.2) Therefore, owing to thesecharacteristics, 169 Yb can be used in theranostics.
Various reactions can be used to produce 169 Yb suchas the neutron-capture reaction on 168 Yb and chargedparticle induced reactions on 169 Tm and nat Er. Amongthese, the best production route has not been determined yet. Therefore, we performed systematic studies on the charged-particle induced reactions to produce 169 Yb such as deuteron- and alpha-induced reactions on 169 Tm and alpha-induced reactions on nat Er.
In this report, we focus on the α-induced reaction on
nat
Er. The cross-sections for these reactions have already been experimentaly measured and reported.3–6)
However, these cross-sections are diﬀerent. Therefore,
we again measured them to ensure a higher accuracy.
The experiment was performed at the AVF cyclotronof the RIKEN RI Beam Factory using the activationstacked-foil method. Metallic foils of nat Er (purity:
99%, Goodfellow Co., Ltd., UK) and nat Ti (purity:
99.6%, Nilaco Corp., Japan) were stacked as the target.
The Ti foils were inserted for the nat Ti(α, x)51 Cr monitor reaction to assess the target thicknesses and beam
parameters. Their average thicknesses were 20.26 and2.24 mg/cm2 , which were derived from their measured
weights and areas. The stacked target was irradiatedfor 1 h by a 50-MeV α beam with an intensity of
100.1 pnA measured with a Faraday cup. The initial beam energy was determined by the time of ﬂight
measurement.8) The energy degradation in the stacked
target was calculated by the SRIM code.9) The irradiated foils were separated and subjected to the γ-ray
spectrometry using a HPGe detector. The nuclear decay data were taken from the NuDat 2.7 database.10)
The cross-sections of nat Ti(α, x)51 Cr monitor reaction were derived from the measurement of γ line at
320.08 keV (Iγ = 9.910%). The result was compared

400
300
200
100
0

10

20

30
40
Energy (MeV)50

60

Fig. 1. Preliminary result of nat Er(α, x)169 Yb comparedwith previous data3–6) and TENDL-2017.7)

with the recommended values of IAEA and we conﬁrmed the accuracy of the foil thicknesses and beam
parameters within the uncertainties.
The γ line at 177.21 keV (Iγ = 22.28%) was used
to derive the cross-sections of 169 Yb. The comparison
between our preliminary result, former experimental
data, and the TENDL-2017 data is shown in Fig. 1.
The peak position of our result is consistent with thedata obtained by B. Király et al. (2008).3) However,
the amplitude of their data is larger than our result.
Other experimental data4–6) are very diﬀerent from ourresult. The TENDL-2017 data show a peak at thesame energy as ours, although the ampulitude of thepeak is lower.
References
1) Neil S. Patel et al., Cardiovasc. Radiat. Med. 2, 173(2001).
2) F. H. DeLand et al., J. Nucl. Med. 12, 683 (1971).
3) B. Király et al., Nucl. Instrum. Methods Phys. Res. B
266, 549 (2008).
4) A. A. Sonzogni et al., J. Radioanal. Nucl. Chem., Lett.
165, 295 (1992).
5) A. Aechenti et al., Radiochemica Acta 38, 65 (1985).
6) Y. Homma et al., Int. J. Appl. Radiat. Isot. 31, 505(1980).
7) A. J. Koning et al., Nucl. Data Sheets 113, 2841
(2012).
8) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566 (2014).
9) J. F. Ziegler et al., SRIM: the Stopping and Range ofIons in Matter, http://www.srim.org/.
10) National Nuclear Data Center, The NuDat 2 database,
http://www.nndc.bnl.gov/nudat2/.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Activation cross sections of alpha-induced reactions on nat In for
117m
Sn production†
M. Aikawa,∗1,∗2 M. Saito,∗3,∗2 N. Ukon,∗4,∗2 Y. Komori,∗2 and H. Haba∗2

†
∗1
∗2
∗3
∗4

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 426, 18 (2018)
Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science, Hokkaido University
Fukushima Global Medical Science Center, Fukushima Medical University- 192 -

200

Cross section (mb)The radioisotope 117m Sn (T1/2 = 13.76 d) can beused as a theranostic radioisotope for both medical
therapy and imaging. The production of 117m Sn isof much concern, and the possible production reactions are studied. We focused on one of the reactions,
namely the 115 In(α, x)117m Sn reaction, in this paper.
Three experimental literature1–3) could be found in the
EXFOR library.4) The literature data, however, show alarge discrepancy from each other. More reliable andaccurate data are required for practical use. Therefore, we performed a new experiment to measure thecross sections of the 115 In(α, x)117m Sn reaction. In addition, the cross sections of the by-products, 113 Sn and
116m, 117, 118m
Sb, were measured.
The experiment was performed at the AVF cyclotronof the RIKEN RI Beam Factory. The stacked foil
technique, activation method, and high resolution γray spectrometry were used to derive the activation
cross sections. Metallic foils of nat In (4.29% 113 In
and 95.71% 115 In) and nat Ti were stacked as a target.
The target was irradiated by a 51.6-MeV α beam for
2 h. The incident beam energy was determined using
the time-of-flight method.5) The beam energy degradation in the stacked target was calculated using the
SRIM code.6) The average intensity of the beam was
202.1 nA, which was measured by a Faraday cup. The
irradiated foils were separated and subjected to γ-ray
spectrometry with an HPGe detector.
The excitation function of the nat Ti(α, x)51 Cr monitor reaction was used to assess the beam parameters and the target thicknesses. The excitation function could be derived from measurements of the γ line
at 320.08 keV (Iγ = 9.91%) from the decay of 51 Cr(T1/2 = 27.7025 d). The result is in good agreementwith the recommended values.7) Therefore, we adopted
the measured beam parameters and target thicknesses
without any adjustments.
The measurement of the 156.02-keV γ line (Iγ =2.113%) from the 117m Sn decay was performed for the
cross sections of the 115 In(α, x)117m Sn reaction. The
cooling time was longer than 45 h for the complete
decay of the parent nuclei, 117g In (T1/2 = 43.2 min),
117m
In (T1/2 = 116.2 min), and 117 Sb (T1/2 = 2.80 h).
The cumulative cross sections of 117m Sn for nat In targets were obtained from the measurement. The cross115

In(α,x)117mSn

150

Fukushima+ (1963)
Qaim+ (1984)
Bhardwaj+ (1992)
TENDL2017
This work

100

50

0

10

15

20

25

30 35 40
Energy (MeV)

45

50

55

Fig. 1. Excitation function of the 115 In(α, x)117m Sn reaction.

sections were normalized to those for 115 In enrichedtargets, taking into account the negligibly small contribution of the α-capture reaction on 113 In. The resultis shown in Fig. 1 in comparison with the previous experimental data1–3) and the TENDL-2017 data.8) The
present result is almost consistent with the data obtained by Qaim and Döhler (1984).2) The data obtained by Fukushima et al. (1963)1) and TENDL-2017
show smaller amplitudes than the others. On the contrary, the data obtained by Bhardwaj et al. (1992)3)
are much larger than that obtained by the others.
In this work, the cross sections of the 115 In(α,117m
Sn reaction up to 50 MeV were measured usx)
ing the stacked foil activation technique and high resolution γ-ray spectrometry. The measured cross sections were compared with the earlier experimental data
and the TENDL data. One of the three experimental
datasets is in good agreement with our result. Our
result can contribute to the estimation of 117m Sn production.
References
1) S. Fukushimai et al., Bull. Chem. Soc. Jpn. 36, 1225
(1963).
2) S. M. Qaim et al., Int. J. Appl. Radiat. Isot. 35, 645(1984).
3) M. K. Bhardwaj et al., Int. J. Mod. Phys. E 1, 389(1992).
4) N. Otuka et al., Nucl. Data Sheets 120, 272 (2014).
5) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566 (2014).
6) SRIM: the Stopping and Range of Ions in Matter, http://www.srim.org/.
7) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2017).
8) A. J. Koning, D. Rochman, Nucl. Data Sheets 113, 2841
(2012).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Investigation of alpha particle induced reactions on natural silver in the
40–50 MeV energy range†
F. Ditrói,∗1 S. Takács,∗1 H. Haba,∗2 Y. Komori,∗2 M. Aikawa,∗3 M. Saito,∗4 and T. Murata∗5
1.E+02

In-110g

Cross secon (mb)

500

400
Takacs 2010
this work

300

TENDL-2017
EMPIRE
Wasilewsky 1985

200

100

0
0

10

20

30

40

50

Alpha energy (MeV)

60

70

80

Fig. 1. Excitation function of the nat Ag(α, x) 110g In reaction
compared with the previous results and the results of thetheoretical model code calculations.
†
∗1
∗2
∗3
∗4
∗5

In-111 this work + Takacs 2010 +Haasbroek 1976

1.E+00700600In-109g this work + Takacs 2010 +Tarkanyi 2015

1.E+01

Integral yield (GBq/C)

Natural silver targets were irradiated using a 50 MeV
alpha-particle beam in order to measure the activation
cross sections of radioisotopes in the 40–50 MeV energy
range. Among the radio-products, there are medicallyimportant isotopes such as 110m In and 111 In.1) For optimizing the production of these radioisotopes and theirpurity and specific activity, the cross section data forevery produced radioisotope are important. New data
were measured in this energy range and the results ofsome previous measurements were confirmed. Physicalyield curves were calculated using the new cross section
data completed with the results from the literature.
The irradiation was performed on a dedicated beamline of the K70-MeV AVF cyclotron of the RIKEN
RI Beam Factory by using an Eα = 50.7 ± 0.3 MeV
beam. The nat Ti(α, x)51 Cr reaction on titanium foils(Ti: 10.9 µm) was used as a monitor reaction to checkand correct the beam intensity and energy degradation
through the whole stack. The foils were ordered ingroups in such a way that we could compensate or avoid
the activity loss or excess activity due to the recoil effect of the radioisotope in question. The first 10 foils of
the stack were silver. The Ag foils were arranged in one
block, i.e. one after other, because for silver, we wereCondensed from the article in Nucl. Instrum. Methods Phys.
Res. B 436, 119 (2018)
Institute for Nuclear Research, HAS
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Graduate School of Biomed. Sci. and Eng., Hokkaido Univ.
School of Science, Hokkaido University- 193 -

1.E-01

Cd-109 this work + Haasbroek
1976

1.E-02
1.E-03
In110g this work +Takacs 2010

1.E-04
1.E-05

Ag-110m this work + Takacs 2010

Ag-106m this work + Takacs 2010In-111 this work + Takacs 2010 + Haasbroek 1976
In110g this work + Takacs 2010
In-109g this work + Takacs 2010 + Tarkanyi 2015
Ag-110m this work + Takacs 2010
Ag-106m this work + Takacs 2010
Ag-105g this work + Takacs 2010
Cd-109 this work + Haasbroek 1976
In-111 Abe 1984
In-110g Abe 1984
In-109g Abe 1984

1.E-06
Ag-105g this work + Takacs 2010

1.E-07
1.E-08
0

10

20

30

40

50

60

70

80

Alpha energy (MeV)

Fig. 2. Calculated physical yields from selected α-particle
induced nuclear reactions on Ag compared with the literature data.

interested in the high energy part (40–50 MeV range).
The excitation functions for nat Ag(α, x)111,110m, 110g,
109g 108g
In, 111, 110m, 106m, 105g Ag and 109 Cd were measured in the energy range of 40–50 MeV (e.g. 110g In
in Fig. 1). The newly determined cross section data
helped clarify the problems between the previous literature results. The cross section deduced for the production of 110g In, 109g In, 108g In, 111 Ag, and 110g Ag in mostcases show a good continuation of the eventually existing literature data in a lower energy region. In the caseof 111 In and 109 Cd, the agreement with the previous
literature data is excellent. The results of the theoretical nuclear reaction model codes are not systematicand give only partly good estimations for several reactions. There are reactions, for which both (EMPIRE
and TENDL) fail completely. Thick target physicalyield curves were calculated from the measured crosssections (Fig. 2). The excitation functions for thesecalculations were constructed by using our new results
combined with data from the literature. The literature
values agree well with our results.
Among the possible industrial applications, theTLA2) method was demonstrated by using 106m Ag,
which is the best radioisotope for this purpose. It has
been proved that by using 106m Ag as a tracer, the wear
measurement can be performed with actual parameters.
References

1) F. Tárkányi et al., Nucl. Instrum. Methods Phys. Res. B
351, 6 (2015).
2) F. Ditrói et al., IAEA TECDOC-924, 1997.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Production cross sections of deuteron-induced reactions on natural
palladium for Ag isotopes†
N. Ukon,∗1,∗2,∗3 M. Aikawa,∗3,∗4 Y. Komori,∗3 and H. Haba∗3Radioisotopes (RI) are available for medical therapy and diagnostics.1) 103 Pd with a half-life of T1/2
= 16.991 d decays (100% electron capture (EC)) into
103m
Rh, which successively decays (100% isomeric transition) into 103 Rh with a 39.5-keV γ-ray emission. 103 Pd
is a medical radioisotope and is available for brachytherapy.2) For the eﬀective production of 103 Pd, a variety ofreactions should be investigated for comparison, including reactions to produce 103 Ag (T1/2 = 65.7 min), which
is a parent of 103 Pd. One of the processes used for producing 103 Ag is deuteron-induced reactions on natural
palladium, which has only been studied up to 20.3 MeV
in previous studies.3–5)
In addition to 103 Pd, the radionuclide 104g Ag which
has a short β + decay half-life (T1/2 = 69.2 min) can beused for diagnostic imaging in positron emission tomography (PET). 111 Ag has signiﬁcant potential as a therapeutic β − radionuclide decaying (92% β − , Eβ max ) =1037 keV) directly to the ground state of 111 Cd. The
PET using 104 Ag has the possible combination of diagnostic studies to investigate the uptake of 111 Ag labelled compounds of the therapeutic radionuclide before
treatment.6) Ag, 104m, g Ag, and 111 Ag can be obtained bycharged particle reactions on nat Pd. Therefore, we investigated the activation cross sections of deuteron-induced
reactions on metallic foils of natural palladium (102 Pd
1.02%; 104 Pd 11.14%; 105 Pd 22.33%; 106 Pd 27.33%;
108
Pd 26.46%; 110 Pd 11.72%) in connection with the
production of medically relevant radioisotopes.
The excitation functions of the nat Pd(d, x) reactions
were measured by the stacked-foil method, activation
method and high-resolution γ-ray spectroscopy. nat Pd
foils (purity: 99.95%, Nilaco Corp., Japan) were stacked
with nat Ti (purity: 99.6%, Nilaco Corp., Japan) andnat
Zn foils (purity: 99.95%, Nilaco Corp., Japan) for
monitoring the beam parameters and degrading thebeam energy. The thicknesses of the Pd, Ti, andZn foils were 8.15, 4.93, and 25.14 mg/cm2 , respectively.The irradiation was performed at the RIKEN AVF
cyclotron. A 24-MeV deuteron beam with an average intensity of about 174 nA was irradiated on the target for
20 min. The incident beam energy was measured by
the time-of-ﬂight method using plastic scintillator monitors. The beam energy degraded in the stacked target
was calculated using the polynomial approximation of
stopping-power data.7) The γ-ray spectra of the acti†
∗1
∗2
∗3
∗4

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 426, 13 (2018)
Nuclear Reaction Data Center (JCPRG), Hokkaido University
Advanced Clinical Research Center, Fukushima Medical University
RIKEN Nishina Center
Faculty of Science, Hokkaido University

Fig. 1. Excitation function of the nat Pd(d, x)103 Ag reaction.
The result is compared with a previous study4) andTENDL-2017.9)

vated foils were measured using HPGe detectors. The
nuclear decay data were taken from the online NuDat
2.6 database.8)
We found that our result is in good agreement withthe previous data obtained by Hermanne et al.4) up
to 20.3 MeV. On the other hand, the theoretical calculation reproduces well the experimental cross sections up to 15 MeV; however at higher energies, thecalculation overestimates the experimental cross sections. We performed an experiment of the deuteroninduced reactions on natural palladium to produce Ag
isotopes by using the stacked foil activation technique.
The excitation functions of the nat Pd(d, x)103 Ag reaction from 20.3 MeV to 24 MeV, nat Pd(d, x)104g Ag, andnat
Pd(d, x)104m Ag were measured for the ﬁrst time. The
production cross sections of 105 Ag, 106m Ag, 110m Ag, and111
Ag are in good agreement with the previous experimental data. Above 20.3 MeV, all excitation functionsin this work continued smoothly to the data in the previous study.
References
1) J. F. Chatal, C. A. Hoefnagel , Lancet 354, 931 (1999).
2) A. S. Meigooni, R. Nath, Int. J. Radiat. Oncol. Biol. Phys.
22, 1125 (1992).
3) F. Ditrói, et al., Nucl. Instrum. Methods Phys. Res. B
270, 61 (2012).
4) A. Hermanne et al., Radiochim. Acta 92, 215 (2004).
5) F. Ditrói et al., Appl. Radiat. Isot. 128, 297 (2017).
6) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 217, 193 (2004).
7) H. H. Andersen, J. F. Ziegler, Hydrogen Stopping Powers
and Ranges in All Elements, Vol. 3 (Pergamon, Oxford,1997).
8) National Nuclear Data Center: the NuDat 2 database,
http://www.nndc.bnl.gov/nudat2/.
9) A. J. Koning et al., TENDL-2017: TALYS-based evaluated nuclear data library.

- 194 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Production cross sections of 111 Ag in deuteron-induced nuclear
reactions on natural palladium
K. Ooe,∗1 T. Watabe,∗1 Y. Shirakami,∗1 D. Mori,∗2 T. Yokokita,∗2 Y. Komori,∗2 H. Haba,∗2 and J. Hatazawa∗1∗1∗2

natPd(d, x)111Ag

50
Cross section/mb

Several radionuclides such as 90 Y and 131 I are currently used for nuclear medicine therapy of tumors.
These radionuclides are produced using nuclear reactors. In Japan, all therapeutic radionuclides are now
imported from other countries. Therefore, domestic
production using accelerators is desirable for a stablesupply of therapeutic radionuclides.
Silver-111 (111 Ag) is a β − emitter, which can be applied to the therapy of tumors. It has a half-life of
7.45 d and can be produced in 110 Pd(d, x)111 Ag reactions using accelerators. This radionuclide also emits
γ rays with energies of 342 and 245 keV, which canbe used for imaging by single photon emission computed tomography (SPECT). These nuclear propertiesof 111 Ag are expected to be suitable for theranostics(therapeutics + diagnosis). However, 111 Ag has beenrarely applied to the nuclear medicine ﬁeld. In thisstudy, production cross sections for nat Pd(d, x)111 Ag
reactions are investigated for future nuclear medical
application of 111 Ag.
The cross sections of nat Pd(d, x)111 Ag reactions
were measured by the stacked-foil method. Metallic
foils of natural isotopic Pd (purity: 99.95% and thickness: 0.0125 mm, Nilaco Corp., Japan) were used as
the target. Metallic foils of nat Ta (purity: 99.95%
and thickness: 0.10 mm, Nilaco Corp., Japan) andnat
Ni (purity: 99.95% and thickness: 0.001 mm, Nilaco Corp., Japan) were also used as a beam energy degrader and beam intensity monitor with thenatNi(d, x)61 Cu reactions, respectively. Twenty ﬁve
Pd and 10 Ni foils were stacked together with 2 Ta foils
which were placed on the top of the stack. The irradiation of the stack with the 24 MeV deuteron beam wasconducted using the RIKEN K70 AVF Cyclotron. The
stack covered the beam energy range of 4–17 MeV forthe measurement of cross sections of nat Pd(d, x)111 Ag
reactions. The average beam intensity was approximately 180 nA and the irradiation time was 2 h. Afterthe irradiation of the stack, each foil was subjected to
γ-ray spectrometry using a HPGe detector. The 245keV γ peak of 111 Ag was used to calculate the crosssections.
Because 110m Ag would be produced simultaneouslywith 111 Ag and remain in the body for a long timeowing to its very long half-life (249.79 d) during radiotherapy, the cross sections of nat Pd(d, x)110m Ag reactions were also investigated. The preliminary results of the cross sections of the nat Pd(d, x)111 Ag and
Department of Nuclear Medicine and Tracer Kinetics, Osaka
University Graduate School of Medicine
RIKEN Nishina Center- 195 -

This work
Hermanne et al.1)
Ukon et al.2)
Ditrói et al.3)

40

natPd(d, x)110m Ag

30This work

20
10
0
0

5

10
15
20
Beam energy/MeV

Fig. 1. Excitation functions ofnat
Pd(d, x)110m Ag reactions.

nat

25

Pd(d, x)111 Ag andnat

Pd(d, x)110m Ag reactions are shown in Fig. 1. 111 Ag
is produced not only in the direct nuclear reaction but
also from the decay of by-products 111m Ag (T1/2 =64.8 s) and 111m Pd (T1/2 = 5.5 h). Therefore, cumulative cross sections for 111 Ag are shown in Fig. 1.
The energy at the peak of the excitation function ofnat
Pd(d, x)111 Ag reactions was approximately 9 MeV
with a cross section of approximately 40 mb, which isconsistent with the previous results.1–3) The excitation
function of nat Pd(d, x)110m Ag reactions has a maximum of approximately 40 mb at around 14 MeV andalmost half amplitude of that of the nat Pd(d, x)111 Ag
reactions at around 9 MeV. Although 110m Ag is simultaneously produced with 111 Ag, the radioactivity of
110m
Ag produced with 9-MeV deuteron beam would
be approximately 1% of the 111 Ag activity owing to
the diﬀerence in cross sections and half-lives between
111
Ag and 110m Ag.
As the next step for the medical application of 111 Ag,
chemical puriﬁcation of 111 Ag from a Pd target will be
performed by ion exchange chromatography.
References
1) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 217, 193 (2004).
2) N. Ukon et al., Nucl. Instrum. Methods Phys. Res. B
426, 13 (2018).
3) F. Ditrói et al., Nucl. Instrum. Methods Phys. Res. B
270, 61 (2012).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Production cross sections of Mo, Nb and Zr radioisotopes fromα-induced reaction on nat Zr†
T. Murata,∗1,∗2,∗3 M. Aikawa,∗3,∗2 M. Saito,∗3,∗2 N. Ukon,∗4,∗2 Y. Komori,∗2 H. Haba,∗2 and S. Takács∗5

†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Appl. Radiat. Isot. 144, 47(2019)
School of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Advanced Clinical Research Center, Fukushima Medical
University
Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI)- 196 -

300

96

Cross section (mb)

Chowdhury 1995
Pupillo 2014
Hagiwara 2018
TENDL2017
This work #1
This work #2

99

Zr(α,x) Mo

250
200
150
100
50
0

0

5

10

15
20
25
Energy (MeV)

30

35

40

Fig. 1. Excitation function of the 96 Zr(α, x)99 Mo reaction.
3
Activity at EOB (MBq/µA)

The most important medical radioisotopes atpresent are 99m Tc (T1/2 = 6.0 h) and its generator
99
Mo (T1/2 = 66.0 h). Nuclear reactions to produce
99
Mo using accelerators are energetically investigatedworldwide. One of the charged-particle reactions used
to create 99 Mo is the 96 Zr(α, x)99 Mo reaction. Threeexperimental data1–3) were found in a literature survey. The three datasets, however, show quite diﬀerent shapes from each other. Therefore, we performed
two experiments to measure the cross sections of the96
Zr(α, x)99 Mo reaction. In addition, the cross sections
for the production of 93m Mo, 90g, 92m, 95g, 95m, 96 Nb,
and 88, 89g, 95 Zr isotopes were measured.
Two independent irradiations using diﬀerent targets
and α-beam energies were performed at the RIKEN
AVF cyclotron. The stacked-foil technique, activation
method, and high-resolution γ-ray spectrometry wereused. Two stacked targets consisted of nat Zr foils of different thicknesses (6.75 and 13.22 mg/cm2 ) and nat Ti
foils (2.43 and 2.40 mg/cm2 ). The targets were respectively irradiated for 2 h by α beams of two diﬀerent
energies, namely 29 and 50 MeV. The incident beamenergies were determined by using the time-of-ﬂight
method.4) The energy degradation in the targets wascalculated using the SRIM code.5) The average intensity measured by a Faraday cup was about 400 nA in
both cases. The γ lines from the decay of the radioisotopes for each irradiated foil were measured using an
HPGe detector.
The excitation function of the nat Zr(α, x)99 Mo reaction was derived from measurements of the γ line at739.500 keV (Iγ = 12.20%). The parent nuclei of 99 Mo,
99g
Nb (T1/2 = 15.0 s), and 99m Nb (T1/2 = 2.5 min), decayed during cooling times longer than 47 h. The crosssections of 96 Zr were deduced by taking into accountthe isotopic composition of natural zirconium. The results are shown in Fig. 1 and compared with previous
experimental data1–3) and the TENDL-2017 data.6)
Our results are in complete agreement with the recent
experimental data,3) but very diﬀerent from the others.
Based on our measured excitation function, the end ofbombardment activity of 99 Mo was deduced with theAbe (1984)
Pupillo (2014)
Hagiwara (2018)
This work

99

Mo

2.5
2
1.5
1
0.5
0

5

10

15

20
25
Energy (MeV)30

35

Fig. 2. End of bombardment activity of 99 Mo for 1 h irradiation.

stopping powers obtained using the SRIM code.5) Our
result shown in Fig. 2 is almost consistent with the twodatasets,3,7) but larger than one dataset.2)
References
1) D. P. Chowdhury et al., Nucl. Instrum. Methods Phys.
Res. B 103, 261 (1995).
2) G. Pupillo et al., J. Radional. Nucl. Chem. 302, 911(2014).
3) M. Hagiwara et al., J. Radioanal. Nucl. Chem. 318, 569(2018).
4) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566 (2014).
5) SRIM: the Stopping and Range of Ions in Matter,
http://www.srim.org/.
6) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).
7) K. Abe et al., J. Nucl. Mater. 123, 972 (1984).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Activation cross sections of deuteron-induced reactions on niobium
up to 24 MeV†
M. Aikawa,∗1,∗2 Y. Komori,∗2 and H. Haba∗2

†
∗1
∗2

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 436, 217 (2018)
Faculty of Science, Hokkaido University
RIKEN Nishina Center- 197 -

Ditroi 2000
Tarkanyi 2007
Avrigeanu 2013
TENDL2017
This work

Cross section (mb)

200
150

93

Nb(d,x)93mMo

100
50
0

0

5

10

15

20

Energy (MeV)

Fig. 1. Excitation function of the 93 Nb(d, 2n)93m Mo reaction.

250

Dmitriev 1983
Ditroi 2016
This work

93m

Mo

Physical yield (MBq/µAh)

One of the potential radioisotopes for nuclear
medicine is 93m Mo.1) Several reactions to produce
93m
Mo were studied, for example, proton- anddeuteron-induced reactions on Nb, α-induced reactions
on Zr, and 7 Li-induced reactions on Y. In this paper, we focus on the deuteron-induced reactions on
Nb because the cross sections of these reactions areabout four times larger than those of the protoninduced reactions.2) Four experimental data sets up
to 50 MeV2–5) were found in a literature survey, andthey were scattered over several tens of mb at apeak of around 17 MeV. Therefore, we performed
an experiment to measure the cross sections of the93
Nb(d, 2n)93m Mo reaction.
We used standard methods such as the stackedfoil activation method and oﬀ-line γ-ray spectrometry.
The stacked target of the experiment was composedof thin metallic foils of 93 Nb (27.11 mg/cm2 , 99.9%
purity, Nilaco Corp., Japan) and nat Ti (9.13 mg/cm2 ,99.6% purity, Nilaco Corp., Japan). The nat Ti foils
were used to monitor the beam parameters. The target was irradiated by a 23.6-MeV deuteron beam at
the AVF cyclotron of the RIKEN RI Beam Factory.
The incident beam energy was measured by the timeof-ﬂight method using a plastic scintillator monitor.6)
The irradiation lasted for 30 min with an average intensity of 200.3 nA, which was measured using a Faraday cup. The energy degradation of the beam in thestacked target was calculated using the SRIM code.7)
The beam parameters and the target thicknesses wereassessed by the nat Ti(d, x)48 V monitor reaction. The
γ lines from the foils were measured by using a highresolution HPGe detector.
The 263.049-keV γ line (Iγ = 57.4%) from the
93m
Mo IT decay (T1/2 = 6.85 h) was measured after acooling time of about 10 h. The excitation functionof the 93 Nb(d, 2n)93m Mo reaction was derived fromthe measurement. The result is shown in Fig. 1 together with the earlier experimental data3–5) and the
TENDL-2017 data.8) Our result shows good agreementwith the other experimental data in the entire energy
region. The theoretical calculation overestimates theexperimental data.
The physical yield of 93m Mo from the 93 Nb(d,2n)93m Mo reaction was calculated from the excitation
function using the spline ﬁtting shown in Fig. 1 and thestopping power calculated by the SRIM code.7) The re-

200
150
100
50
0

0

5

10

15

20

25

Energy (MeV)

Fig. 2. Physical yield of 93m Mo.

sult, together with the other experimental data,2,9) isshown in Fig. 2. Our result is consistent with the twodata studied earlier.2,9)References
1) M. Sadeghi et al., J. Radioanal. Nucl. Chem. 286, 141(2010).
2) F. Ditrói et al.,, Nucl. Instrum. Methods Phys. Res. B
373, 17 (2016).
3) F. Ditrói et al., Nucl. Instrum. Methods Phys. Res. B
161–163, 172 (2000).
4) F. Tárkányi et al., Nucl. Instrum. Methods Phys. Res.
B 255, 297 (2007).
5) M. Avrigeanu et al., Phys. Rev. C 88, 014612 (2013).
6) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566 (2014).
7) SRIM: the Stopping and Range of Ions in Matter, http://www.srim.org/.
8) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
9) P. P. Dmitriev et al., INDC(CCP)-210, 1 (1983).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

New cross section data for production of zirconium-89 byalpha-induced reaction on yttrium target
T. Murata,∗1,2 M. Aikawa,∗1,2 M. Saito,∗1,2 N. Ukon,∗2,3 Y. Komori,∗2 H. Haba,∗2 S. Takács,∗4 and F. Ditrói∗4
Zirconium-89 is considered a good candidate for
immuno-PET investigations owing to its decay properties.1) Even though it is possible to produce 89 Zr with a
low incident beam energy (approximately 12 MeV) andhigh speciﬁc activities by using proton beams (470–1195 mCi/mmol),1) it is worthwhile to consider its
production using heavier particles. Co-production of90
Nb, another expectable radionuclide for medicine,2)is possible in the same irradiation with alpha particles.
The alpha-induced reaction on natural yttrium is
one of the ways to produce 89 Zr and 90 Nb. There are,however, only two earlier studies on the 89 Y(α, x)89 Zr
reaction and no data for the high energy region is available, where higher cross sections seem to be achieved.
In this work, a new experiment to measure the crosssections for the 89 Y(α, x)89 Zr reaction was performed
to investigate the optional route for 89 Zr production.
The well known stacked-foil technique and activation method were used to measure the cross sections forthe alpha-induced reactions on natural yttrium. The
stacked-foil target consisted of yttrium (25 µm, Nilaco), titanium (5 µm, Nilaco), and aluminum (5 µm,
Nilaco) foils. The thicknesses were veriﬁed within 0.6%
by measuring the sizes and weights of the foils. The
stacked-foil target was attached to a target holder,which also served as a Faraday-cup, and was irradiated with a 50-MeV alpha beam with an intensity of
200 pnA for 1 h using the AVF cyclotron at the RIKEN
beam factory. The energy of the alpha beam in eachfoil was calculated using stopping powers that wereobtained from the SRIM software.3) The intensity was
assumed to be constant in the target. The correctness of the beam parameters and foil thicknesses waschecked by monitoring the reactions on aluminum andtitanium foils by comparing their cross sections with
the IAEA recommended values.
After the irradiation, a cooling time of over 40 min
was taken to reduce the background radiation, which
is an obstacle for the measurement. A high purity germanium detector was used to collect the gamma-ray
spectra from the foils. To derive the cross sections of
the monitored reactions, the 1274.5 keV (Iγ = 99.94%)
and 320.08 keV (Iγ = 9.91%) gamma-lines were used
for nat Al(α, x)22 Na and nat Ti(α, x)51 Cr reactions, respectively. The data obtained from the monitored re∗1
∗3
∗2
∗4

Graduate School of Biomedical Science and Engineering,
Hokkaido University
Advanced Clinical Research Center, Fukushima Medical
University
Nishina Center for Accelerator-Based Science, RIKEN
Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI)- 198 -

Fig. 1. Experimental cross sections of 89 Y(α, x)89 Zr reaction with earlier experimental data and TENDL data.

actions was signiﬁcantly consistent with the IAEA recommended values.
A speciﬁc gamma-line of 909.15 keV (Iγ = 99.04%)
from 89 Zr was used to derive the cross sections of
the 89 Y(α, x)89 Zr reaction. Owing to the short halflife of 89 Nb (T1/2 = 2.03 h) as compared to 89 Zr(T1/2 = 78.41 h), the derived cross sections were cumulative. The cross sections of 89 Zr are shown in
Fig. 1 in comparison with earlier two experiments4,5)
and TENDL data.6) Our result is consistent with Levkovski’s result and indicates that the TENDL values
are overestimated at higher energy.
In this work, the peak position of the cross sectionsof 89 Y(α, x)89 Zr reaction could not be obtained. To
ﬁnd the most eﬃcient energy for 89 Zr production byalpha particles, another experiment using a higher energy alpha beam is needed. In addition to the peak
position of the excitation function, the evaluation of
speciﬁc activity and yields of other co-produced nuclei
is needed for the practical application of 89 Y(α, x)89 Zr
reaction.
References

1) M. A. Deri et al., Nucl. Med. Biol. 40, 3(2013).
2) V. Radchenko et al., Nucl. Med. Biol. 41, 721(2014).
3) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
4) V. N. Levkovski, Cross Sections of Medium Mass Nuclide Activation (A = 40–100) by Medium Energy Protons and Alpha Particles (E = 10–50 MeV) (Inter-Vesi,
Moscow, 1991).
5) M. Shahid et al., Nucl. Instrum. Methods Phys. Res. B
42, 158(2015).
6) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Cross section measurement of the deuteron-induced reaction on 89 Y
to produce 89 Zr
M. Sakaguchi,∗1,∗2 M. Aikawa,∗2,∗3 M. Saito,∗2,∗3 N. Ukon,∗2,∗4 Y. Komori,∗2 and H. Haba∗2
Zirconium-89 (T1/2 = 78.41 h) is a positron emitter, which can be used for the diagnostic imaging
of Positron Emission Tomography (PET). There aremany routes to produce 89 Zr. The 89 Y(p, n)89 Zr reaction and the 89 Y(d, 2n)89 Zr reaction can be quoted as
their examples. The former is better known, as many
experiments have been performed on this reaction during the last several decades. In contrast, only sevenexperiments with the latter1–7) could be found in theliterature. The behaviors of the excitation functions of
the latter disagree with each other and there are only afew previous experiments that show cross sections over
20 MeV. These facts are obstacles to deciding the mosteﬃcient way to obtain this radionuclide. Therefore, we
performed an experiment on the 89 Y(d, 2n)89 Zr reaction and measured the cross sections up to 24 MeV.
We adopted the standard stacked-foil activation
method for this experiment. The target consisted of89
Y foils (purity: 99.0%, thickness: 28.6 μm; Goodfellow Co., Ltd., UK) and nat Ti foils (purity: 99.6%,
thickness: 20.3 μm; Nilaco Corp., Japan), whichwere used for the nat Ti(d,x)48 V monitor reaction.
This stacked target was positioned in a target holder
served as a Faraday cup and irradiated by a 23.6-MeV
deuteron beam for 1 h at the RIKEN AVF cyclotron.
The average beam intensity was 102.3 nA, which wasmeasured by using the Faraday cup. The energies ofthe projectile going through each foil and their uncertainties were calculated by using the SRIM8) code.
After a cooling time of approximately 1 h, we disassembled the stacked foils and measured the γ-ray
spectra on each foil by using an HPGe detector. The
909.15-keV γ-line (Iγ = 99.04%) following the decay of89
Zr and the 983.525-keV γ-line (Iγ = 99.98%) following the decay of 48 V were measured to derive the crosssections of the 89 Y(d, 2n)89 Zr and nat Ti(d, x)48 V reactions, respectively. Keeping the dead time less than
5%, the distance between the measured foils and the
HPGe detector was adjusted in every γ-ray measurement.
The cross sections of the nat Ti(d, x)48 V reaction
were derived, and it was conﬁrmed that their values
agree with the IAEA recommended values, which indicates the correctnesses of the thicknesses and beam
parameters within the uncertainties.
∗1
∗2
∗3
∗4

School of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Advanced Clinical Research Center, Fukushima Medical
University- 199 -

Fig. 1. Excitation function for the 89 Y(d, 2n)89 Zr reaction
compared with the previous experimental data and the
TENDL data.

Figure 1 shows the excitation function of theY(d, 2n)89 Zr reaction in this work in comparison
with the previous data and the TENDL9) data. Our
result indicates that the peak of the excitation function
is located at around 17.9 MeV and the corresponding
cross section value is approximately 970 mb. These
values are almost the same as that of some of the previous data. On the other hand, the cross section valuesof the TENDL data are higher than those of all the experimental data in the range between 10 and 20 MeV.
In this work, we performed an experiment on the89
Y(d, 2n)89 Zr reaction at the RIKEN AVF cyclotron.
The stacked foil activation method and γ-ray spectrometry were used for this experiment. The crosssections of this reaction were measured up to 24 MeV.
Our result is consistent with some of the previous data.
The production yield of 89 Zr in this reaction will be derived and compared with that in other reactions.
89

References
1) O. Lebeda et al., Nucl. Instrum. Methods Phys. Res. B
360, 118 (2015).
2) M. S. Uddin et al., Radiochim. Acta 95, 187 (2007).
3) H. I. West et al., UCRL-ID-115738, 1 (1993).
4) D. Digering et al., J. Radioanal. Nucl. Chem. Lett. 127,
7 (1988).
5) H. H. Bissem et al., Phys. Rev. C 22, (4), 1468 (1980).
6) A. M. La Gamma, S. J. Nassif, Radiochim. Acta 19,
161 (1973).
7) N. Baron, B. L. Cohen, Phys. Rev. 129, 2636 (1963).
8) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
9) A. J. Koning et al., Nucl. Data Sheets, 113, 2841 (2012).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Activation cross sections of alpha particle induced reactions
on natural nickel up to 50 MeV
S. Takács,∗1 F. Ditrói,∗1 H. Haba,∗2 Y. Komori,∗2 M. Aikawa,∗3,∗2 M. Saito,∗4,∗2 and T. Murata∗5,∗2
Cu is a medium-energy β − emitter radionuclide,which is similar to 177 Lu, but oﬀers the advantage ofradiation suitable for diagnostics along with a therapy
eﬀect. We investigated the 64 Ni(α, p)67 Cu reaction byirradiating natural nickel targets. Cross sections ofalpha particle-induced reactions, resulting in the production of 61,64,67 Cu, 55, 56, 57, 58, 60 Co, 56, 57, 66 Ni, and62, 63, 65
Zn were determined, and the results were compared with data available in the literature.
The stacked target technique and activation method
were used, followed by high-resolution gamma spectrometry of the activated target foils. Two independent irradiation experiments using diﬀerent target foils and irradiation parameters were performedat the AVF cyclotron of the RIKEN RI Beam Factory. The stacked targets consisted of nat Ni target
foils (4.11 mg/cm2 and 4.45 mg/cm2 ) and nat Ti monitor foils to monitor the beam parameters (2.40 and
4.95 mg/cm2 ) of diﬀerent thicknesses. The targets
were irradiated for 1 and 2 h with alpha beams of 186
and 400 nA and energies of Eα = 41.6 ± 0.35 MeV andEα = 50.73 ± 0.30 MeV, respectively. The primarybeam energies were determined by the time-of-ﬂight
method.1) The energy degradation in the targets wascalculated by the semiempirical polynomial method ofZiegler et al.2) The beam intensity was measured by a
Faraday cup and was recorded every minute to checkits stability in both cases.
The activity of the foils was measured by a HPGe
spectrometer to identify the isotopes and to determine
their intensity. The nat Ti(α, x)51 Cr reaction was used
to monitor the beam intensity and energy degradation
through the whole stack. It was not necessary to correct the beam parameters obtained from primary measurements. The foils were placed in pairs in the stack
and activity of the lower energy foil of each pair wasmeasured supposing compensation of the activity loss
due to the recoil eﬀect.
The newly determined cross section data from thetwo irradiations correspond well in the overlapping energy region and can be used as one dataset. Because
only the 64 Ni(α, p) reaction contributes to the production of 67 Cu, the measured data were normalized to the
100% 64 Ni target composition and were compared tothe experimental data measured earlier as well as to

40

67

∗1
∗2
∗3
∗4
∗4

Institute for Nuclear Research,Hungarian Academy of Sciences
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Graduate School of Biomed. Sci. and Eng., Hokkaido University
School of Science, Hokkaido University- 200 -

64Ni(α,p)67Cu

35

This work
Tanaka 1960
Antropov 1985

30

Takacs 1996

Cross section (mb)

Skakun 2004
Levkovskij 1991

25

TENDL 2017
Spline fit of all data

20
15
10
5
0

0

5

10

15

20

25

30

35

40

45

50

Energy (MeV)

Fig. 1. Excitation function of the 64 Ni(α, p)67 Cu comparedwith the previous results and with the results of theoretical model codes.

the results of the theoretical nuclear reaction model
code TALYS (Fig. 1) taken from the TENDL-2017
data library available online.3)
From the measured cross sections, yield curves were
calculated and compared with the available experimental yield data. Our results agree well with most values
in the literature except for the data of Tanaka (1960)4)and Antropov (1985).5)
Our preliminary data are, in general, in agreementwith data in the literature, however, an additional experiment is required to cover the 20 MeV-to-thresholdenergy region of the excitation function. Owing to
the high energy degradation of the alpha particles theusual stacked target technique cannot be used eﬀectively below 20 MeV. Therefore, a new rotating irradiation setup is designed for measurements in this energy
region.
References
1) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), 3566 (2014).
2) J. F. Ziegler, Helium stopping powers and ranges in allelements, (Pergamon Press, New York, 1978).
3) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
TENDL-2017: Database available from: https://
tendl.web.psi.ch/tendl_2017/tendl2017.html
4) Tanaka et al., J. Phys. Soc. Jpn. 15, 2159 (1960).
5) Antropov et al., 35. Conf. Nucl. Spectr. and Nucl.
Struct., Leningrad (1985).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Measurement of half-lives of 181, 182a, 182b, 183, 184m Re and 187 W
Y. Komori∗1 and H. Haba∗1
Chemical characterization of superheavy elements is
one of the most important and challenging subjects innuclear chemistry. We plan to conduct model experiments for the chemical studies of element 107, Bh,using radiotracers of its homologs, Tc and Re. Longlived 95m Tc (T 1/2 = 61 d), 183 Re (T 1/2 = 70 d),
and 184m, g Re (m: T 1/2 = 169 d; g: T 1/2 = 35.4 d)
are useful for the model experiments. These isotopes
are producible in the deuteron-induced reactions on
nat
Mo and nat W (nat: natural isotopic abundance) using the RIKEN AVF cyclotron. Previously, we measured the production cross-sections of the Re isotopes
in the nat W(d, x) reactions for the quantitative production of 183, 184m, g Re.1) In the course of measurements, we noticed that the half-lives of some Re isotopes such as 181, 183 Re was slightly shorter than thoseadopted in literatures. Furthermore, recently, the halflife of 182a Re has been revised from 12.7 ± 0.2 h2)
to 14.14 ± 0.45 h3) because Bonardi et al. and Manenti et al. suggested that the half-life of 182a Re is
13.74 ± 0.48 h4) and 14.50 ± 0.45 h,5) respectively.
Therefore, it is worth reinvestigating the half-lives ofthese Re isotopes. In this work, we measured thehalf-lives of 181, 182a, 182b, 183, 184m Re and 187 W and compared them with the half-life values adopted in the
Nudat 2.7 database.6)
We determined the half-lives of 181, 182a, 182b Re and187
W using a reference source method. Four nat W foils
with a thickness of 20 μm were irradiated for 5 minwith 24 MeV deuteron beam supplied from the RIKEN
AVF cyclotron. The average beam current evaluatedwith the Faraday cup was 425 nA. After the irradiation, three of the nat W foils were repetitively measured with three Ge detectors every 4 h or 6 h with88
Y (T1/2 = 106.626 ± 0.021 d7) ). 88 Y was used as thereference source to correct the dead time during the radioactivity measurement.8) The cooling time and deadtime were ≥ 1.6 h after the end of bombardment (EOB)
and ≤ 12.8%. The internal clock time of the computerfor data acquisition was synchronized with the Internet
time server in RIKEN every 1 h.
As for the long-lived isotopes, 183, 184m Re, we determined their half-lives by following their interferencefree γ lines under low dead time condition of ≤ 3.0%.
A nat W foil with a thickness of 100 μm irradiated withthe 24 MeV deuteron beam for 125 min with a beam
current of 5 pμA, was repetitively measured every 12 hwith the Ge detector at the cooling time of 474 d after
the EOB.
The half-lives of 181, 182a, 182b, 183, 184m Re and 187 W
determined in this work are listed in Table 1 along withthose adopted in the Nudat 2.7 database.6) We found∗1

RIKEN Nishina Center- 201 -

Table 1. Half-lives adopted in Nudat 2.76) for 181, 182a, 182b,
183, 184m
Re and 187 W and those determined in this work.
Gamma energy (E γ ) used for analysis in this work is also
listed.

NuclideEγ [keV]

Half-life(Nudat 2.7 )Half-life(this work)

6)Re

19.9 ± 0.7 h9)953.6

18.94 ± 0.05 hRe

14.14 ± 0.45 h3)

470.2614.33 ± 0.03 h

Re64.2 ± 0.5 h3)1427.362.6 ± 0.5 h

187W

24.000 ± 0.004 h10)685.8123.92 ± 0.04 h

183

Re

70.0 ± 1.4 d11)

291.72366.5 ± 0.1 d

Re

169 ± 8 d12)318.008

178.7 ± 0.4 d

920.933

178.5 ± 0.4 d

181

182a

182b

184m

that the half-life of 181 Re is 18.94±0.05 h, which is 0.96h shorter than the literature data of 19.9 ± 0.7 h.9) The
half-life of 182a Re is 14.33 ± 0.03 h, which is consistent
with the value of 14.50 ± 0.45 h reported by Manenti etal.5) and the recently revised value of 14.14 ± 0.45 h bySingh.3) The half-life of 182b Re is 62.6 ± 0.5 h, which is
1.6-h shorter than the literature value of 64.2 ± 0.5 h.3)
The half-life of 187 W is 23.92 ± 0.04 h, which is slightly
shorter than the literature value of 24.000 ± 0.004 h.10)
The half-life of 183 Re is 66.5 ± 0.1 d, which is 3.5-d
shorter than the literature data of 70.0 ± 1.4 d.11) The
half-lives of 184m Re determined by the decays of 318keV and 921-keV γ lines are 178.5±0.4 and 178.7±0.4 d,respectively. The average half-life of 184m Re is 178.6 ±0.3 d, which is 9.6-d longer than the literature data of
169 ± 8 d.12) For further discussion, we will compare
our newly determined half-lives of these isotopes withthe previously reported values.
References

1) Y. Komori et al., RIKEN Accel. Prog. Rep. 49, 245(2016).
2) B. Singh, J. C. Roediger, Nucl. Data Sheets 111, 2081
(2010).
3) B. Singh, Nucl. Data Sheets 130, 21 (2015).
4) M. Bonardi et al., Radiochim. Acta 99, 1 (2011).
5) S. Manenti et al., Radiochim. Acta 102, 669 (2014).
6) Nudat 2.7, Nat. Nucl. Data Center, Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/.
7) E. A. McCutchan, A. A. Sonzogni, Nucl. Data Sheets
115, 135 (2014).
8) H. Kikunaga et al., Proc. Radiochim. Acta 1, 113(2011).
9) S.-c. Wu, Nucl. Data Sheets 106, 367 (2005).
10) M. S. Basunia, Nucl. Data Sheets 110, 999 (2009).
11) C. M. Baglin, Nucl. Data Sheets 134, 149 (2016).
12) C. M. Baglin, Nucl. Data Sheets 111, 275 (2010).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Production of Np isotopes in nuclear reactions
for standard material in accelerator mass spectrometry
Y. Hayakawa,∗1 A. Yokoyama,∗2 A. Sakaguchi,∗3 K. Yamamori,∗1 K. Sekiguchi,∗3 S. Yanou,∗4 Y. Komori,∗4
T. Yokokita,∗4 and H. Haba∗4
The techniques for highly sensitive mass spectrometry, such as ICP-MS and AMS, are rapidly being developed currently. Several elements or nuclides thatwere not supposed to be applicable in those techniques
several decades ago are now quantitatively analyzed.
Especially, for long-lived actinides elements, the techniques are becoming more important as a promisingalternative to radioactivity measurements. The tracer
nuclide for target elements, which is non-existent innature and absent in target samples, is necessary toestablish a standard in the new techniques. Tracers
for several elements are available now but the tracer
for neptunium has not been developed yet. We aim todevise an eﬃcient method for the production of Np236 in the ground state of half life 1.54 × 105 y as a
candidate for tracer nuclide.
In this study, the Np tracer production was implemented in the reactions of 232 Th + 7 Li and 238 U + p
to measure Np-237 in environmental samples.
For irradiation, target stacks of Th metal foils of two
tytpes of thickness were prepared: a thin target for theexcitation function measurement and a thick target for
tracer production of Np. A silver foil was irradiated at
the same time to monitor the beam intensity from theradioactivity of 111 In generated during the irradiation
with current integration using a beam course equippedwith Faraday cup.
We irradiated the targets with 42 MeV 7 Li ions fromthe RIKEN AVF cyclotron. Chemical procedures were
performed to isolate Np atoms from the target. As
an example of the procedure, the target material was
dissolved in 3 M HNO3 with Np-239 tracer to checkchemical recoveries and the sample was dried by heating. The residue was then dissolved in conc. HCl,
repeatedly dried three times, and ﬁnally adjusted to
3 M HNO3 solution of 4 ml. This solution was introduced into a TEVA resin column, subsequently treatedwith 3 M HNO3 and 10 M HCl for puriﬁcation, and ﬁnally treated 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 andby-products, γ-ray spectrometry was conducted for theeﬄuents with a Ge detector.
As an example of the result, a measured γ spec∗1
∗2
∗3
∗4

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
RIKEN Nishina Center- 202 -

Fig. 1. Example of γ spectrum of isolated Np. (Red: Np236m, Green: Np-234)

Fig. 2. Exciting functions of 236m Np in reactions of 238 U +p and 232 Th + 7 Li.

trum is shown in Fig. 1, where many photopeaks of
Np isotopes including Np-236m are observed. Figure 2
compares the excitation function of Np-236m obtained
from this study to that obtained from the 39 MeV p+ U experiment conducted in RCNP of Osaka University. Although the cross section of Th + Li is nearly
two orders of magnitude lower than that of U + p,
it is predicted that the isomeric ratio of Np-236g to
Np-236m for the products of the former reaction islarger than that for the latter, which had been measured to be around 0.5.1) The analysis of the result isstill in progress and additional experiments including
mass spectrometry are in the planning stage at present.
Reference

1) J. Aaltonen, M. Brenner, S. A. Egorov, A. M. Fridkin, V. B. Funschtein, E. A. Gromova, P. Manngård,V. A. Rubchen’a, Yu. A. Selitsky, V. A. Yakovlev,
V. S. Zenkevich, Phys. Rev. C 41, 513 (1990).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Column chromatography of astatine using weak base anion exchange
resin
H. Ikeda,∗1,∗2,∗3 H. Kikunaga,∗2,∗3 Y. Komori,∗3 T. Yokokita,∗3 D. Mori,∗3 H. Haba,∗3 and H. Watabe∗1Astatine (At) is one of the nuclides expected to be
applied for targeted α-particle therapy (TAT). Several
methods for At separation are known. Two methods (dry distillation1) and wet extraction2,3) ) are usedmainly. Dry distillation can obtain a pure solution of
At without impurities; however, it requires the construction of a complicated apparatus.1) On the other
hand, although wet extraction is a simple method, theaqueous solution is contaminated with the organic solvent after back extraction. To solve these problems,
we tried At separation using column chromatography.4)
However, the eluent was too alkaline for biological studies. Therefore, we need to find a solution with mild
conditions. In the general wet separation of At, it isnecessary to dissolve bismuth metal or bismuth oxide(Bi2 O3 ) into nitric acid. We examined the dissolution
method using hydrochloric acid (4 M HCl).4) However,large amounts of anions other than astatide anion (At− )existed in the solution, which was used to dissolve the
Bi2 O3 target in our study. This influenced the behavior of At in column chromatography, and we could notachieve a high yield of At tracer. In this work, we reconsidered the chemical operation. Improvement of the
dissolution method of the Bi2 O3 target and the conditions of column chromatography were investigated. The
radioactivity was measured with a high-purity germanium detector. The quantitation of 211 At was carriedout with γ-ray at 687 keV (Iγ = 0.261%).
We produced 211 At at the RIKEN Nishina Center using the 209 Bi(α, 2n)211 At reaction (29 MeV, 250 particle nA, 30 min). A Bi2 O3 pellet was used as the target.
The irradiated target was added to 12 mL of 0.25 M
EDTA · 2Na solution and 0.01 M L-ascorbic acid solution in a 50 mL tube. By shaking this mixture for
60 min, the Bi2 O3 target was completely dissolved.
This solution was used for column chromatography
studies. 3-Aminopropyl Silica Gel (Tokyo Chemical Industry Co., Ltd.) was used as the weak anion exchange
resin, and 1 mL (7 mmϕ × 26 mm) of the resin wasR
Mini-column (M size). Thisfilled into the Muromac⃝
was flushed with 25 mL of EtOH, 10 mL of H2 O, and10 mL of 1 M L-Ascorbic acid in this order (conditioning).
On dissolving the Bi2 O3 target, 71% of 211 At was adsorbed to the 50 mL tube. Column chromatography was
carried out using the 211 At remaining in the solution.
The operations and results are shown in Fig. 1. We
found that 211 At could be separated with a 50% yield
∗1
∗2
∗3

Cyclotron and Radioisotope Center, Tohoku University
Research Center for Electron Photon Science, Tohoku University
RIKEN Nishina Centerat a more mild condition (0.3–1 M NaOH). However,
7–25% and 1–7% of 211 At were lost at the charge andwashing processes, respectively. The column residue of211
At was 15–22%. The separation method of At in ourstudy is still unstable and has to be improved.
Run 1
5 mL of stock solution(211At 100% = 79.9 kBq)

10 mL of H2O

10 mL of
0.3 M NaOH

Weak Base Anion Exchange Column

3-Aminopropylsilica Gel (TCI) in Muromac® Mini-column size M
211At: 19.8 kBq(24.8%)

211At: 0.6 kBq(0.8%)

Residue in column

211At: 17.8 kBq (22.3%)

211At: 40.4 kBq(50.6%)

Run 2
5 mL of stock solution(211At 100% = 79.9 kBq)

10 mL of H2O

10 mL of
0.3 M NaOH

Weak Base Anion Exchange Column

3-Aminopropylsilica Gel (TCI) in Muromac® Mini-column size M
211At: 5.7 kBq(7.3%)

211At: 0.8 kBq(1.1%)

Residue in column

211At: 14.8 kBq (18.5%)

211At: 12.8 kBq(73.9%)

Run 3
5 mL of stock solution(211At 100% = 152 kBq)

10 mL of H2O

10 mL of
1 M NaOH

Weak Base Anion Exchange Column

3-Aminopropylsilica Gel (TCI) in Muromac® Mini-column size M
211At: 36.2 kBq(23.8%)

211At: 9.9 kBq(6.5%)

Residue in column

211At: 21.0 kBq (13.8%)

211At: 82.7 kBq(54.3%)

Fig. 1. Methods and results of column chromatography.
Run 1 and Run2 had the same conditions; however, theresults did not show the same behavior.

References
1) S. Lindegren et al., Appl. Radiat. Isot. 55, 157 (2001).
2) M. S. Sultana et al., J. Radioanal. Nucl. Chem. 243, 631(2000).
3) C. Zona et al., J. Radioanal. Nucl. Chem. 276, 819(2008).
4) H. Ikeda et al., RIKEN Accel. Prog. Rep. 51, 227 (2017).

- 203 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Speciation analysis of oxidation states of astatine
extracted into ethanol-water solutions
Y. Shin,∗1 K. Kawasaki,∗1 K. Aoi,∗2 K. Washiyama,∗3 A. Yokoyama,∗2 I. Nishinaka,∗4 S. Yanou,∗5 and H. Haba∗5
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 a halflife of 7.21 h, which has gained popularity owing to its
appropriate life and possible compounds as a halogen
element. This has been the motivation behind several
preclinical studies on At-chemistry1) However, the successive chemical processes for the general use of Atchemistry has not been well studied. We aim to study
the wet chemistry processes of At that may form a prevailing technology.
In previous studies,2,3) the At-211 radioactivity wasrecovered eﬃciently from an irradiated Bi target in thechemical systems of dodecane and ethanol solution withoxidizing agents such as N-bromosuccinimide (NBS)
and bromine water, which supply Br2 . However, themechanism of solvent extraction was not clariﬁed in the
study. Here, we performed a thin layer chromatography(TLC) experiment to investigate the oxidation states ofAt species extracted into the system with NBS as wellas bromine water, in reference to a TLC study on At
species.4)
The At-211 radioactivity was produced via 209 Bi(α,2n) reaction at the RIKEN AVF cyclotron and delivered
to Kanazawa University. The irradiated Bi target wasdissolved in 2 mL of 6 M HNO3 and diluted with 10 mL
of H2 O to prepare a 1 M HNO3 solution, from which
the 211 At nuclide was extracted into the dodecane solvent. Aliquots of the solution were subjected to backextractions into 90% ethanol solution with NBS or Br2
water after 15 min of its addition or without an oxidizing agent. 10 μL from each sample of 211 At (ca. 15 to
50 Bq) obtained in the back extractions was spotted on
a TLC plate (Merck Silica gel 60 F254 aluminum sheet,
10 × 2 cm) and developed with 50% ethanol solution for
90 min (7 cm in ﬂow distance). After drying, the plate
was exposed to an imaging plate for 10 to 20 min to
perform an image analysis of its radioactivity.
The images of TLC demonstrated in Fig. 1 suggestthat three diﬀerent species were separated. The results of the analysis exhibit that the oxidizing agents of
Br2 water and NBS signiﬁcantly increase the oxidized
species of AtO4 − instead of decreasing the others’ as
∗1
∗2
∗3
∗4
∗5

Institute and College of Science and Engineering, Kanazawa
University
Graduate School of Natural Science and Technology,
Kanazawa University
Fukushima Global Medical Science Center, Fukushima Medical Unversity
Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology
RIKEN Nishina Center- 204 -

compared to the case without an oxidizing agent. This
indicates that such oxidation due to the agents causes
distribution among the species and enhance the distribution ratio of At during extraction. Therefore, theback-extraction favors the oxidized species instead ofAt− .

Fig. 1. Imaging of 211 At radioactivity on thin-layer chromatography for (a) Br2 water, (b) NBS, and (c) no oxidizing agent (see text for detail).

Table 1. Distributions of At chemical species in extracted
solutions.

Chemicalspecies
At㸫
AtO3㸫
AtO4㸫

Br2 water

NBS

No addition

12 %
47 %
41 %

13 %
45 %
42 %

23 %
57 %
20 %

References
1) F. Guérard, J-F. Gestin, M. W. Brechbiel, Cancer Biother. Radiopharm., 28, 1 (2013).
2) E. Maeda, A. Yokoyama, T. Taniguchi, K. Washiyama,
I. Nishinaka, J. Radioanal. Nucl. Chem. 303 (2), 1465
(2015).
3) Y. Shin, K. Kawasaki, N. Yamada, K. Washiyama,
A. Yokoyama, I. Nishinaka, S. Yanou, H. Haba, RIKEN
Accel. Prog. Rep. 51, 228 (2018).
4) I. Nishinaka, K. Hashimoto, H. Suzuki, J. Radioanal.
Nucl. Chem. 318, 897 (2018).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Purification of 121m Te by anion exchange chromatography
T. Kubota,∗1,∗2 K. Iwata,∗1 S. Fukutani,∗1 T. Takahashi,∗1 H. Haba,∗2 D. Mori,∗2 and S. Takahashi∗1
Radioactive tellurium nuclides, such as 129 Te, 131 Te,
and 132 Te, were released into the environment by the
Fukushima accident. These are the parent nuclide ofradioactive iodine, 129 I, 131 I, and 132 I, respectively, regarded as critical for internal exposure, and their ﬁssion
yield is relatively high. The data on the environmental
behavior of tellurium are required to estimate the radiation doses after the accidents. To obtain such data,
tracer experiments using radioactive tellurium are essential. This report describes the puriﬁcation of 121m Te toprepare an adequate tracer for plant and animal experiments.
Tellurium-121m was produced by the bombardmentof Sb2 O3 pellets with 24 MeV deuterons at the RIKEN
AVF cyclotron.1) Sb2 O3 powder with a purity of
99.999% was pressed to form a pellet with a diameterof 15 mm. The irradiated pellets were transported to
the Institute for Integrated Radiation and Nuclear Science, Kyoto University for further treatment.
Tellurium was puriﬁed from antimony by anion chromatography where two methods were applied, namely,
Downs’s method2) and its modiﬁcation. Downs et al.
reported that the irradiated sample dissolved in HCl
was diluted to 2 M HCl and then added with hypochlorite, thereby separating tellurium and antimony by anion chromatography.2) In the other method, the mixture of antimony dissolved in conc. HCl and NaClO
was poured into an anion exchange column and thentellurium was recovered in eluant.
Figure 1 shows the result of an attempt to purify tellurium by the Downs’s method where only antimony is
expected to be eluted with 2 M HCl. Both elements

Fig. 1. Recovery of tellurium and antimony in each eluate.
L denotes the loading solution of 1 mL and E1, E2, andE3 denote the eluent of 2 mL of 2 M HCl.
∗1
∗2

Institute for Integrated Radiation and Nuclear Science, Kyoto
University
RIKEN Nishina Center

Fig. 2. Recovery of tellurium and antimony in each eluate.
L denotes the loading solution of 1.4 mL and E denotes
the eluent of a mixture of conc. HCl and 5% NaClO in
the ratio of 10:1 (v/v).

were, however, similarly eluted; hence, tellurium cannot
be puriﬁed.
Figure 2 shows the puriﬁcation of tellurium by themodiﬁcation method. Tellurium was eluted ﬁrst in thereverse elution order described in Downs’s method andwas consequently separated from antimony with a recovery of 60%.
Antimony forms Sb(V)-chloro complex ion in oxidizing HCl3) to be strongly adsorbed onto anion exchange
resin. Thus, the concentration of antimony in the eluate
can be ignored for the loading solution in both methods. The fate of antimony depended on the following
eluents, whose redox potential and chloride concentration are critical for the separation where tellurium can beobtained without antimony when both values are high.
Because Te(VI) is not adsorbed onto the anion exchange resin at any concentration of HCl,4) the valencyof tellurium in the eluate is 6 and that of remaining
would be 4. The rate of redox reaction with NaClO isconsidered to aﬀect the elution property. Therefore, anappropriate regulation of redox potential would yield ahigher tellurium recovery with high purity. In addition,
the disadvantage of the puriﬁcation method used here
naturally causes to evolve toxic chlorine gas.
The puriﬁcation method was established to provide a
tracer of carrier free radioactive tellurium without antimony. Further investigations are still required from theperspective of safety as well as recovery.
References

1) T. Kubota et al., RIKEN Accel. Prog. Rep. 50, 254 (2017).
2) D. Downs, D. A. Miller, J. Rad. Nucl. Chem. 262, 241 (2004).
3) C. Yoshimura et al., Japan Analyst 13, 1249 (1964).
4) K. Kimura et al., Japan Analyst 7, 174 (1958).

- 205 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Production of arsenic RI tracer from gallium oxide target
by alpha beam irradiation
H. Ikeda,∗1,∗2,∗3 H. Kikunaga,∗2,∗3 Y. Komori,∗3 T. Yokokita,∗3 D. Mori,∗3 H. Haba,∗3 and H. Watabe∗1
Arsenic (As) is toxic to living beings. Therefore, it
is considered one of the most important environmental
pollutants. Contamination of soil by As signiﬁcantly
inﬂuences the living environment and agriculture. Phytoextraction is an eﬀective method to remove As fromthe contaminated soil.1) Thus it is necessary to determine the plant species that can eﬃciently extract As
to achieve eﬀective As removal. We need to investigate
which plant species more eﬃciently extract arsenic toachieve eﬀective arsenic removal. We believe that plant
imaging using radioisotope (RI) is eﬀective for that purpose. Arsenic is known to be stable in the trivalent andpentavalent oxidation states. However, it is suggested
that the pentavalent arsenic species are predominant insoil due to the biological activity of transforming microorganisms.2) Therefore, the arsenic species in thesame oxidation state as in soil are preferred for ourpresent purpose. It was recently reported3,4) that the72
Se(T1/2 = 8.5 d)/72 As(T1/2 = 26.0 h) generator was
prepared from a germanium target irradiated with protons. The tracer from the method, however, includes
beta emitters useless for the positron imaging. In thisstudy, we aim to develop a method for the tracer preparation of 74 As (T1/2 = 17.77 d), a positron emitter using the reaction system of a gallium (Ga) target withalpha particles for less contamination of beta emittersin the tracer. The 74 As radioactivity was measured
by gamma-ray spectrometry with a high-purity germanium detector.
0.1 g of Ga2 O3 powder was formed into pellets(10 mmϕ). Each pellet was covered with an aluminum
foil (10 µm thickness) and used as a target. The target
was irradiated with an alpha beam (29 MeV, 1.5 pµA)
for 30 min. Following processes for tracer preparation were started after the byproducts such as 71 As(T1/2 = 65 h) and 72 As decayed out at least 4 weeks after the irradiation. The irradiated Ga2 O3 was dissolvedin 1 mL of 12 M NaOH by heating up to 80◦ C. 917 mg
of non-irradiated Ga2 O3 was dissolved in 9 mL of 12 M
NaOH and added to the target solution, which was neutralized into a pH of 4 to 5 with ca. 2 mL of 6 M HCl andchanged into the suspending solution. The suspension
was subjected to solvent extraction with 5 mL of 1 M
Di-(2-ethylhexyl)phosphoric acid (HDEHP) organic solution with either of benzene, toluene, and 1-octanol
by shaking for ca. 1 h. The aqueous phase from solvent
extraction with toluene or benzene was processed into
the following chemical treatment after precipitation of
∗1
∗2
∗3

Cyclotron and Radioisotope Center, Tohoku University
Research Center for Electron Photon Science, Tohoku University
RIKEN Nishina Center- 206 -

Table 1. Arsenic yields extracted into aqueous phase.

solventbenzenetoluene1-octanol

yield (%)

66.5 ± 0.8

65.8 ± 0.940.2 ± 0.5

sup. 50 mL(ca. 95% EtOH)

H2O
20 mL

0.1 M HCl
20 mL

mnion exchange resin column 2 mL (7.5 mm∅ × 45 mm)

74ms: n.d.

(discard)

74ms~1%(discard)

74ms fraction(~90%)

Fig. 1. A part of the scheme for As tracer preparation.

NaCl by adding ethanol.
The supernatant collected from the aqueous solution
was treated after measuring its radioactivity, as depicted in Fig. 1, where a chromatography column ofR
2 mL anion exchange resin of Muromac⃝
1 × 8 100–200−
R
Minimesh (Cl form) ﬁlled into the 30 Muromac⃝
column M (7.5 mmϕ × 45 mm) was used. This column
was ﬂushed with 20 mL of H2 O, 20 mL of 1 M NaOH,
and 20 mL of H2 O in a sequential order. The ion form of
the resin was changed from Cl− to OH− in the preparative conditioning. The supernatant was charged into
the column, which was ﬂushed with 20 mL of H2 O toremove ethanol and undesired species. After that, 74 As
was eluted with 20 mL of 0.1 M HCl.
Table 1 presents the results of solvent extraction. The
recoveries of 74 As isotope are nearly the same for benzene and toluene except for 1-octanol. The loss of 74 As
in coprecipitation with NaCl was ca. 1.7%. The column chromatographic process in Fig. 1 lost ca. 10%of the charged 74 As onto the column. We successfully prepared an 74 As tracer solution including 60%of the produced radioactivity in a Ga2 O3 target combining solvent extraction and anion exchange column
chromatography.
References
1) M. Lei et al., Env. Sci. and Poll. Res. 25, 124 (2018).
2) R. E. Macur et al., Env. Sci. and Tech. 38, 104 (2004).
3) M. Jahn et al., Radiochim. Acta 98, 807 (2010).
4) D. E. Wycoﬀ et al., J. Chromatogr. A 1340, 109 (2014).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Production of 44m Sc for multiple-isotope PET
T. Fukuchi,∗1 S. Yano,∗2 H. Haba,∗1 and Y. Watanabe∗1
We have been working toward the development of anext-generation positron emission tomography (PET)system, known as multiple-isotope PET (MI-PET). MIPET is designed to coincide with γ-ray using additional detectors and identify the tracer by detecting theprompt γ-ray, which is emitted after positron emission
from positron-γ emitter. Figure 1 shows an image andschematic illustration of the developed MI-PET system.
The system is composed of a PET system and additional γ-ray detectors. The PET system consists of pixelized gadolinium orthosilicate (GSO) scintillation detectors and has a ring geometry with an inner diameter
and width of 95 mm and 37.5 mm, respectively. Eightbismuth germanium oxide (BGO) scintillation detectors
constitute the additional eight detectors, each with adimension of 50 × 50 × 30 mm3 , arranged in two rings
mounted on each side of the PET ring.1)
For multiple-isotope imaging using MI-PET, atleast one positron-γ emitter is necessary as a tracer.
Scandium-44 is one of the candidates for the specific radioactive tracer for MI-PET owing to its large positronand γ-ray emission ratio and moderate half-life (44 Sc:
3.97 h, 44m Sc: 58.61 h). Therefore, we studied the production of 44m Sc and its imaging using MI-PET.
For 44m Sc production, we used nat CaO powder as thetarget material, which was pressed into a disk with an inner diameter and thickness of 10-mm and 376-mg/cm2 ,respectively. The target was irradiated for 3 h with a
24-MeV deuteron beam having an intensity of 3.0 µA
at the RIKEN AVF cyclotron. The irradiated CaO target was dissolved in 6 M HCl and evaporated to becomedry. Subsequently, the residue was dissolved in 5 mL of
2 M HCl. The solution was passed through an anion
exchange resin column (DGA resin, particle size: 50–
100 µm) filled in a Muromac column.2) The resin wasthen washed with 5 mL of 2 M HCl and 44m Sc was eluted
from the resin with 10 mL of 0.1 M HCl. Finally, approximately 2.0 MBq of 44m Sc with 90% radiochemical

Fig. 1. Image (left) and schematic illustration (right) of thedeveloped PET system.
∗1∗2

RIKEN Center for Biosystems Dynamics Research
RIKEN Nishina Center

Fig. 2. Illustration of rod phantom configuration.

Fig. 3. The x-y plane projection images of rod phantom. Images were reconstructed with (A) absence or (B) presenceof γ-ray detection.

yield was obtained.
To test the imaging ability of the MI-PET system for
44m
Sc, we scanned a dual radionuclide rod phantom thatcomprised three cylindrical rods with a diameter andlength of 10 mm and 76 mm, respectively. Scandium44m and 18 F (pure positron emitter) dissolved in water were poured into the rods. The first rod had 44m Sc(585 kBq) and 18 F (636 kBq) activities. The second andthird rods had 44m Sc (585 kBq) and 18 F (636 kBq) activities, respectively. The configuration of this rod phantom is illustrated in Fig. 2. The rods were positioned
parallel to the scanner’s axial direction and a 30-min
scan was performed.
Figure 3 shows the reconstructed phantom images as
the x-y plane projection images of the rod phantom withthe absence (A) or presence (B) of γ-ray detection. Fromthese images, the distribution of 44m Sc and 18 F is evident.
This study demonstrates the feasibility of 44m Sc imaging using MI-PET. In future, we will conduct multiple
isotope animal experiments using 44m Sc and the other
PET tracer. We will also synthesize useful MI-PET druglabeled with 44m Sc.
References

1) T. Fukuchi et al., Med. Phys. 40, 6, 2257 (2017).
2) C. Alliot et al., Nucl. Med. Bio. 42, 524 (2015).
- 207 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Adsorption experiments of 88 Y and 143 Pm on in HNO3
T. Yokokita,∗1 S. Yano,∗1 Y. Komori,∗1 and H. Haba∗1
Seventeen elements of Sc, Y, and 15 lanthanides arecalled as rare earth elements (REEs). REEs are used
in a wide range of applications such as semiconductors,
catalysis, lasers, magnets, and neutron absorbents.1) It
is diﬃcult to purify them due to their very similar chemical properties. Therefore, simple and eﬀective mutual
separation methods are needed to obtain pure materials
for the industry.
So far, many extractants have been developed, andsome extractants are commercially available. However,
the adsorption behavior of REEs on those resins were
only reported for some elements in some inorganic solutions. A systematic study of the adsorption behaviorof many elements will be useful for the development of
separation and puriﬁcation technology. In this work, todevelop the separation methods of REEs, we studied theadsorption behavior of Y and Pm using 18 commerciallyavailable resins.
88
Y and 143 Pm were produced in the nat Sr(d, xn)88 Y
and nat Pr(α, xn)143 Pm reactions using the K70 AVF cyclotron at RIKEN and were separated from the target materials using LN resin. In the adsorption experiments, the resins (Actinide, CU, DGA (normal),
DGA (branched), LN, LN2, Muromac 1 × 8, Muromac
50 W × 8, Pb, RE, Sr, TBP, TK 100, TK 101, TK 400,
TRU, UTEVA, and ZR resins) were added in 1 mL of
HNO3 containing 88 Y or 143 Pm in a PP tube, and the
mixture was shaken for 4 h using a mixer. After that,the resin was removed by centrifugation. Subsequently,
the ﬁltrate was pipetted into another tube and weighed
and then subjected to γ-ray spectrometry using a Ge detector. Finally, the HNO3 concentrations of the aqueous
phases were determined by titration with a standardized
NaOH solution. In all the adsorption experiments, control experiments without the resin were performed. The
Kd values were determined from the following equation:
Kd = Ar Vs /As wr = (Ac − As )Vs /As wa(1)

where Ar , As , and Ac are the radioactivities of the resin,
the solution, and the control solution, respectively. Vs isFig. 1. The Kd values of Y and Pm with LN resin as a function of HNO3 concentration.
∗1

RIKEN Nishina Center

Fig. 2. The Kd values of Y and Pm with TRU resin as afunction of HNO3 concentration.

the volume (mL) of the solution, and wa is the mass (g)of the dry resin.
We investigated the Kd values of Y and Pm as functions of HNO3 concentration. The Kd values of Y and
Pm were low (≤20 mL g−1 ) and constant when we used
CU, Muromac 1 × 8, Pb, Sr, TBP, TK 101, TK 400,
UTEVA, and ZR resins in 0.1–13 M HNO3 . It was foundthat these resins are not suitable for the separation of Y
and Pm in HNO3 .
Using DGA (branched) and Muromac 50 W×8 resins,
Y and Pm were adsorbed on the resins in some HNO3
concentrations, and the Kd values of Y agreed with thoseof Pm. Therefore, these resins are not useful for the
separation of Y and Pm from each other.
When Actinide and DGA (normal) resins were used,
the Kd values of Y and Pm were ≥102 mL g−1 , and thevalues were diﬀerent from each other. Y and Pm can beseparated using these resins. However, those Kd values
were ≥102 mL g−1 in 0.1–13 M HNO3 , and both Y and
Pm were adsorbed on the resins. The Y and Pm species
adsorbed on these resins can be stripped by using a large
volume of eluents, and this separation method requires
a long time. It is concluded that Actinide and DGA(normal) resins are not suitable for the separation of Y
and Pm.
Figure 1 shows the dependences of the Kd values of Y
and Pm on the HNO3 concentration in the adsorption
experiment using LN resin. When LN resin is used, theKd values of Y are higher than those of Pm in a high
HNO3 concentration range. The same behavior was observed using LN2 and TK 100 resins. Figure 2 shows the
HNO3 concentration dependences of the Kd values of Y
and Pm on the TRU resin. The Kd values of Y are lower
than those of Pm when TRU resin is used. The same
behavior was obtained with RE resin. It is suggested
that these resins are useful for the separation of Y andPm.
In the future, we will perform adsorption experiments
using other REE elements and discuss about good separation conditions for REEs.
Reference

1) B. Swain, E. O. Otu, Sep. Purif. Technol. 83, 82 (2011).

- 208 -

4. Radiation Chemistry and Biology

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

Development of new cultivar of Hibiscus by C-ion beam irradiation
S. Ochiai,∗1 M. Ochiai,∗1 Y. Ochiai,∗1 Y. Hayashi,∗2 and T. Abe∗2
Hibiscus is a well-known ﬂowering shrub that belongs
to the mallow family (Malvaceae). There are a lot of
cultivated varieties over the world with wide variations
in ﬂower color and shape. It is popular in Japan as an
ornamental plant. We, Hanakongou Co. Ltd., have developed original cultivars of Hibiscus and nine of them
are currently in the market. In this study, we attempted
mutation induction by heavy-ion beam irradiation to increase the variations in ﬂower colors of our original cultivars. Consequently, we successfully developed a newcolor cultivar from ‘mother-pink’ (Fig. 1).
Two kinds of cultivars (‘mother-pink,’ ‘moon-light’)and a strain called dark-red of hibiscus were used forthe irradiation treatment in 2014. The cuttings were irradiated with C-ion beams (LET 23 keV/µm) at dosesof 10, 20, 30, and 40 Gy. The irradiated cuttings wereplanted in the soil and the rooted cutting was cultivatedin a greenhouse. The number of survived plants werecounted after seven months. Table 1 lists the numberof survived plants. There was no decrease in the survival at 20 Gy in ‘mother-Pink’ and ‘moon-light.’ However, the survival rate at 20 Gy was lesser than 50% in
dark-red. We multiplled cuttage from ‘mother-pink’ irradiated with 20 Gy. The growth of irradiated cuttingsvaried individually even with high survival rate. No mutation in the color of ﬂowers or leaves were observed in
the survived 35 plants. We selected the plants with wellrooting from the 35 plants and produced 500 cuttingsin 2015. Some plants grown from these cuttings had
leaves with a lighter color and no mutation in the colorof the ﬂower was observed. Propagation by cutting was
repeated in 2016 and we cultivated 1,300 plants. We
isolated three mutated plants with orange ﬂowers fromthe 1,300 plants. A stability in the ﬂower color mutation was conﬁrmed by cultivating 60 cuttings from threeplants in 2017. Although the ﬂower size, intensity of
ﬂower color, and length of internode were diﬀerent, allplants bloomed with orange ﬂowers. The percentage ofTable 2.

plants that had deep orange colored ﬂowers and suitableinternode length for potted ﬂowers was approximately
90%. We used these plants for propagation. The traitsof the mutant were evaluated in 2018 using 500 cuttingsfrom the selected plant. The characteristics of mutant
ﬂower are listed in Table 2. These traits were almost stable. ‘Mother-Pink’ has a characteristic of continuously
blooming, even in the hot summer season. We conﬁrmedthat the selected mutant maintained this excellent characteristic. This mutant is named ‘mother-orange’ and it
is under application for variety registration.

Fig. 1. Flower of mutant. Original ‘mother-pink’ (left) andnew cultivar ‘mother-orange’ (right).
Table 1. Eﬀect of C-ion beam irradiation on survival in Hibiscus.

Mother-pink
Moon-light
Dark-red

Irradiated
44
40
35
41
40
40
29
30
25

Number of cuttings
Planted
Survived
35
35
23
9
4
0
41
41
40
39
36
8
29
28
30
14
25
1

Comparison of ﬂower characteristics between original cultivar (‘mother-pink’) and mutant.
Shape

Original
Mutant

Dose
(Gy)
20
30
40
10
20
30
10
20
30

Shape

Direction

Diameter

Bud

Trumpet-shaped
Horizontal

Horizontal
Upward

14 cm
12 cm

45A
53B

Color Petal (Banded type)
Band 1
Band 2
155B
52C
5A
N30A

Staminal
column20D
15D

Filament
White
Pale red*: Deﬁnition of color groups from RHS (The Royal Horticultural Society) color chart. 45A: Vivid red, 53B:
Strong red, 155B: Yellowish white, 5A: Brilliant Greenish Yellow, 52C: Deep Pink, N30A: Vivid Reddish
Orange, 20D: Pale yellow, 15D: Light yellow∗1∗2

Hanakongou Co., Ltd.
RIKEN Nishina Center- 209 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

Eﬀect of heavy ion beam irradiation on germination and mutation
rate in local Toraja rice
R. Sjahril,∗1 M. Riadi,∗1 Raﬁuddin,∗1 T. Sato,∗2,∗3 K. Toriyama,∗2 Y. Hayashi,∗3 T. Abe,∗3 andA. R. Trisnawaty∗1
Tana Toraja is one of the areas in South Sulawesi
that has wide local rice germplasm diversity. Basedon the results of a survey of local rice in the Tana
Toraja district, Suhardi et al. found approximately
29 local varieties of Toraja rice, each of which has
exotic characteristics such as brown rice, red, aromatic and glutinous.1) The local rice cultivars have
many unique traits, for example black and red rice.
These colored rice cultivars are in the spotlight as foodwith health-promoting beneﬁts because these pigments
found in them have an antioxidative eﬀect.2) However,improved rice cultivars are expanded in this area. Most
farmers grow no native rice cultivar because the yieldof these cultivars is lower than the improved cultivars
and have long maturity during 5–6 months (Fig. 1). It
is feared this will result in a lack of local rice cultivars
as germplasm materials. Our research aims to improve
the productivity of local cultivars with unique trait byheavy-ion beam irradiation. In this study, we evaluated seed germination as a result of irradiation using
ion beam in two varieties of Toraja local rice.
Pare Ambo and Pare Lea are black and red rice cultivar (Oryza sativa L.) in Tana Toraja, respectively(Fig. 2). Dry seeds packed in a plastic case were irradiated with Ar (309 keV/µm) and C (30 keV/µm)
in RI-beam factory, RIKEN Nishina Center, Japan.
The doses of Argon-ion and Carbon-ion were 10 and
150 Gy, respectively.3,4)
Each grain from one panicle for each M1 plant wasgerminated in one line method on a 15 cm Petri dishand transplanted into small plastic bags. The germiFig. 1. Local red rice “Parelea” has a long culm tending
to lodge.

Table 1. Germination rate (%) on M1 and M2 seeds in
Tana Toraja rice cultivars Pare Ambo and Pare Lea.
BeforeIrradiation

Cultivar
Pare Ambo
Pare Lea

85
98

M1

M2

Irradiation Ion

Irradiation Ion

CarbonArgon

Carbon

Argon

54
97

55
98

85
93

90
94

Table 2. Number of plants undergoing albino mutation in
Tana Toraja rice cultivars Pare Ambo and Pare Lea.
Ion

M2 plants

AlbinoMutation Rate

Carbon Pare Ambo

(No.)
414

(No.)
8

(%)
1.9

Pare Lea

1619

46

2.8

Pare Ambo
Pare Lea

90
1034

1
22

1.1
2.1

Argon

Cultivarnation percentages of seeds used before being irradiated are 85% and 98% in Pare Ambo and Pare Lea,
respectively (Table 1). Ion beam irradiation reduced
the germination percentage of Pare Ambo by approximately 30%. However, the germination percentage
of Pare Lea after irradiation was approximately thesame as before irradiation. M1 seeds of Pare Ambo
and Pare Lea irradiated with Argon-ion produced better seedling growths than Carbon-ion.
Further M2 seed germination shows uniqueness insome seedlings, such as lighter leaf color, albinism andwrinkled leaf, which could prove to be potential mutant
lines in tested M2 lines seed. Chlorophyll mutation inM2 plant was observed through the color of the leaves
ten days after sowing until the plant was transplanted
into the rice ﬁeld. The irradiation treatment with ion
beam also gives rise to chlorophyll mutations as seenin M2 of Pare Ambo and Pare Lea (Table 2). A higher
albino mutation rate was found in M2 population irradiated by carbon ion instead of argon ion in both
cultivars. The occurrence chlorophyll mutation occurring is a mutagenic eﬀect of carbon-ion beam, whichindicates that the treatment is eﬀective in the creationof genetic diversity in the M2 population.
References

Fig. 2. Pre Ambo (Blackrice) and Pare lea (red rice).
∗1
∗2
∗3

Hasanuddin University, Makassar, Indonesia
Tohoku University, Sendai, JapanRIKEN Nisina Center- 210 -

1) Sahardi et al., Proc. of Nat. Sem. on Gen. Res. of Agr.
(2013), pp. 34–43.
2) Rahim et al., Int. J. Pharma. Phytochem. Res. 8, 771–
776, (2016).
3) Y. Hayashi et al., RIKEN Accel. Prog. Rep. 51, 238 (2018).
4) Y. Hayashi et al., RIKEN Accel. Prog. Rep. 50, 27 (2017).

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

Isolation of the chalky grain mutant 13–45 in rice (Oryza sativa L.)
T. Katsube-Tanaka,∗1 R. Tabassum,∗1 T. Dosaka,∗1 C. Masuoka,∗1 M. Tsuyama,∗1 Y. Mukai,∗1 C. Nukigi,∗1
H. Ichida,∗2 R. Morita,∗2 and T. Abe∗2
High temperature during the grain ﬁlling of rice diminishes the grain quality as well as productivity. Chalkvalues and peak head rice yields were quadratically increased and linearly decreased, respectively, against an
increase in the nighttime air temperature during the R8stage where one brown hull appeared on the main stem
panicle.1) Chalky grains have several air spaces between
the starch granules in amyloplast,2) resulting in lowered
palatability3) as well as substantial yield loss due to reduced polishing eﬃciency.4) The molecular mechanism
underlying the rice grain chalkiness is supposed to becomplicated and largely unknown.
In this study, a novel chalky rice mutant was isolated from heavy ion beam (Carbon, 20 Gy, LET: 22.6–
60.3 keV/µm)- irradiated rice (O. sativa ssp. japonica
cultivar Nipponbare) of 1,116 lines. The mutant tentatively named 13–45 showed signiﬁcantly higher chalky
ratio (0.4–0.6), which was deﬁned by the averaged ratioof chalky area to grain area of all brown rice grains withina panicle than the wild type (<0.1) at 28◦ C (Fig. 1).
Meanwhile, the chalky ratio of both the wild type andthe mutant became low (<0.06) and similar to each otherat 24◦ C. These results suggested that the rice grain of
the mutant 13–45 is very sensitive to high temperatureand is useful for the analysis of the mechanism underlying the chalkiness caused by high temperature duringgrain ﬁlling.
Prolamin, the second most abundant and hydrophobic
seed storage protein in rice, is composed of 13 kDa and
10 kDa polypeptides. Prolamin is often demonstrated todecrease under heat stress. When the total seed proteins
were compared by western blotting with anti-10 kDa prolamin antibody, a band around 70 kDa clearly disappeared in the mutant 13–45. The 70 kDa polypeptide of
the wild type was insoluble and puriﬁed by 2D-PAGE for
Peptide mass ﬁngerprinting, resulting in the identiﬁcation of chloroplastic 70 kDa heat shock-related protein:
cpHsp70.
Rice genome contains two cpHsp70 genes: cpHsp701 and cpHsp70-2. The transcription levels for the twogenes were not diﬀerent between the mutant 13–45 andthe wild type. Thus, the coding region and promoter region (∼2 kbp) of the two genes in the mutant 13–45 werecloned and sequenced, demonstrating that a single nucleotide polymorphism (SNP) was exclusively detected
at the 3’ region of the second exon of cpHsp70-2. The
SNP resulted in amino acid substitution of the 259th aspartic acid with valine (D259 V) in an ATPase domain.
The whole exome sequencing analysis of the mutant 13–
45 conﬁrmed that only three homozygous mutations including the SNP in cpHsp70-2 caused non-synonymous∗1∗2

Graduate School of Agriculture, Kyoto University
RIKEN Nishina Center

Fig. 1. External appearance of brown rice for the wild type
(Nipponbare) and mutant 13–45 grown under conventional field condition (high, 28◦ C) and cool temperature
condition (low, 24◦ C).

substitutions and frameshifts in the coding sequences.
Transgenic plants of the mutant 13–45 expressing wild
type cpHsp70-2 were produced and the chalky ratio averaged by six panicles was compared with those of themutant 13–45 and the wild type. The chalky ratio of
the transgenic line 7(6/12) was signiﬁcantly lower (0.08)
than that of the mutant (0.15–0.23) and comparable tothat of the wild type (0.07). The results indicated thatcpHsp70-2 is a causal gene for the chalkiness of the mutant 13–45.
The intrinsic ATPase activity of recombinant cpHsp702 was compared between the mutant 13–45 and the wild
type. The results showed that the Km of the mutant
13–45 type was slightly lower (higher in aﬃnity) thanthat of the wild type and Vmax of the mutant 13–45
type was signiﬁcantly lower by 23% than that of the wild
type. Besides, the growth of DnaK (Hsp70 homologue)defective Escherichia coli (E. coli ) cells complemented
with DnaK with D201 V mutation (equivalent to the rice
D259 V mutation) was signiﬁcantly reduced at 37◦ C. The
growth of DnaK-defective E. coli cells complemented
with wild type DnaK was not diﬀerent from that of the
non-complemented DnaK-defective E. coli cells at 37◦ C.
Taken together, these results suggest that the lowered
function of cpHsp70-2 is involved with the chalkiness ofthe mutant 13–45.
References

1) S. B. Lanning et al., Field Crops Res. 124, 132 (2011).
2) T. Tashiro, I. F. Wardlaw, Aust. J. Agric. Res. 42, 485(1991).
3) S. S. Kim et al., Cereal Chem. 77, 376 (2000).
4) N. Sreenivasulu et al., J. Exp. Bot. 66, 1737 (2015).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

Molecular analysis of the stay-green mutant dye1 induced by carbon ion
beams in rice†
H. Yamatani,∗1 M. Nakano,∗1 Y. Hayashi,∗2 Y. Masuda,∗1 T. Abe,∗2 and M. Kusaba∗1
Chlorophyll synthesis and degradation are carefully
regulated in plants not only because chlorophyll is an essential photosynthetic molecule, but also because in its
free form it can damage cells photo-oxidatively.1) Mutants that retain the green of leaves under senescenceinducing conditions are known as stay-green mutants.
We isolated a stay-green mutant from a rice M2 population (Oryza sativa L.) irradiated with carbon ion beams(1.6 GeV, 23 keV/µm, 20 Gy). It exhibited delayed yellowing during natural senescence in the paddy ﬁeld. This
recessive mutant, named delayed yellowing1-1 (dye1-1 ),was greener than the wild-type cultivar, Nipponbare,ﬁve weeks after heading, when most leaves are senescent(Fig. 1).
We performed map-based cloning of DYE1. An analysis of the F2 population and its progeny revealed that
DYE1 is located on chromosome 8. Fine mapping of
DYE1 delimited the candidate region within 43.1 kb,
which contained seven predicted genes (Fig. 2). A nextgeneration sequence analysis revealed that dye1-1 has a
G-to-A substitution at the second exon of Lhca4, causing amino acid substitution from glutamic acid to lysine(E146K). Lhca4 is a subunit of the light-harvesting complex for photosystem I (PSI). This residue corresponds toE154 in Arabidopsis Lhca4, which is a pigment-bindingsite conserved not only among Lhca subunits but also
among Lhcb subunits (light-harvesting complex for photosystem II) of diﬀerent species.2)
A blue native-PAGE analysis revealed a signiﬁcantchange in the conformation of PSI-LHCI supercomplex
in dye1-1 (Fig. 3). Nevertheless, the biomass of dye1-1
was comparable to that of the wild-type. Interestingly,

Fig. 2. DYE1 encodes Lhca4, a subunit of the PSI antennacomplex LHCI.

Fig. 3. Blue native-PAGE analysis of photosystems. Arrows
indicate newly merged bands in dye1-1.

Fig. 1. dye1 exhibits a stay-green phenotype during natural
senescence (five weeks after heading).
†∗1∗2

Condensed from the article in J. Exp. Bot. 69, 1027–1035(2018)
Graduate School of Science, Hiroshima University
RIKEN Nishina Center

Lhcb1, a subunit of the trimeric LHCII, was highly accumulated in dye1-1. The high accumulation of LHCII
in the LHCI mutant dye1-1 may compensate the reduced PSI activity caused by the impairment of LHCI
antenna (Lhca4), suggesting a novel functional interaction between LHCI and LHCII.
Higher chlorophyll content in leaves is observed before and during senescence in dye1-1, indicating thatthe impairment of Lhca4 inﬂuences chlorophyll synthesis
and/or degradation during the development and senescence of leaves in rice. It will be of great interest to
examine whether mutants of other LHCI subunits showa high chlorophyll content/stay-green phenotype.
References

1) Tanaka et al., The Arabidopsis Book 9, e0145, (2011).
2) A. N. Melkozernov, R. E. Blankenship, J. Biol. Chem.
278, 44542–44551, (2003).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

An early-flowering einkorn wheat mutant with deletions of
PHYTOCLOCK 1/LUX ARRHYTHMO and VERNALIZATION 2
exhibits a high level of VERNALIZATION 1 expression induced
by vernalization†
A. Nishiura,∗1 S. Kitagawa,∗1 M. Matsumura,∗1 Y. Kazama,∗2 T. Abe,∗2 N. Mizuno,∗3 S. Nasuda,∗3
and K. Murai∗1
The early-ﬂowering or early-heading phenotype in
bread wheat (Triticum aestivum) cultivars is importantas it can produce an early harvest. This characteristic isparticularly beneﬁcial in East Asia as it allows harvesting
to before the onset of the rainy season. To understandthe molecular mechanism of ﬂowering in wheat, we developed a large-scale mutant panel in diploid einkorn wheat(T. monococcum) using a heavy-ion beam.1) Einkorn
wheat seeds were exposed to a heavy-ion beam andthen sown in the ﬁeld. Selfed seeds from each spike of
M1 plants were used to generate M2 lines. Every year
over the past 15 years, we have obtained approximately
1,000 M2 lines and built up a mutant panel with 10,000
M2 lines. This mutant panel is being systematicallyscreened for mutations aﬀecting reproductive growth, especially for the ﬂowering-time mutants. From the large
scale mutant panel, we have identiﬁed four extra earlyﬂowering mutants, named extra early-flowering1 (exe1 ),
exe2, exe3, and exe4.2) The four exe mutants fall into twogroups namely Type I (moderately extra early-ﬂowering
type: exe1 and exe3 ) and Type II (extremely extra earlyﬂowering type: exe2 and exe4 ). An analysis of VERNALIZATION 1 (VRN1 ), a ﬂowering promoter gene,shows that it is more highly expressed in seedlings at
early developmental stages in both Type I and II mutants than wild-type (WT). These ﬁndings indicate thatthe diﬀerence in earliness between Type I and II mutants
is associated to the level of VRN1 expression.
The diﬀerences between the diurnal gene expression
patterns in the ﬁeld were examined for four clock-related
genes and three clock downstream genes in WT andexe3 mutant plants grown in the ﬁeld, respectively. The
biggest diﬀerence was found for a clock-related gene,
PHYTOCLOCK 1/LUX ARRHYTHMO, which is abbreviated to Wheat PCL1 (WPCL1 ). The WPCL1 was
not expressed in the exe3 mutant plants, whereas it was
highly expressed during sunset in WT plants. PCR analysis of DNA markers indicated that the exe3 mutant
had a deletion of WPCL1 in the genome, which was cosegregated with the mutant phenotype in the segregationline.
We conﬁrmed that the original strain KU104-1 carried a mutation that produced a null allele of a ﬂowering repressor gene VERNALIZATION 2 (VRN2 ). As
†

∗1
∗2
∗3

Condensed from the article in J. Plant Physiol. 222, 28 (2018)
Faculty of Bioscience and Biotechnology, Fukui Prefectural
University
RIKEN Nishina Center
Graduate School of Agriculture, Kyoto University

Fig. 1. Model for the extra early-flowering phenotype in theexe3 mutants compared with wild-type. (A) Wild-type,(B) exe3 mutant

a result, the exe3 mutant has both WPCL1 and VRN2
loss-of-function mutations. The analysis of plant development in a growth chamber showed that vernalization
treatment accelerated ﬂowering time in the exe3 mutant
under short day (SD) as well as long day (LD) conditions and the early-ﬂowering phenotype was correlatedwith the earlier up-regulation of VRN1. The deletionof WPCL1 aﬀects the SD-speciﬁc expression patterns ofsome clock-related genes, clock downstream genes, andphotoperiod pathway genes, suggesting that the exe3
mutant causes a disordered SD response. The present
study indicates that VRN1 expression is associated withthe biological clock and the VRN1 up-regulation is notinﬂuenced by the presence or absence of VRN2.
A model for the extra early-ﬂowering phenotype of
exe3 mutant is shown in Fig. 1. The disruption of clockfunction also aﬀects the expression of the ﬂorigen gene
WFT through the VRN1 expression. A high level of
WFT expression was observed in the exe3 mutant under LD conditions, suggesting that the disrupted clock
somehow induces WFT expression. Under SD conditions, another ﬂorigen gene could be up-regulated by the
disrupted clock function and accelerate ﬂowering in theexe3 mutant. The up-regulation of VRN1 is controlled
by the vernalization pathway and clock function. It is not
related to VRN2 and determines the earliness in wheat.
References
1) K. Murai et al., Nucl. Instrum. Methods Phys. Res. B
314, 59 (2013).
2) A. Nishiura et al., Breed. Sci. 64, 213 (2014).

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RIKEN Accel. Prog. Rep. 52 (2019)

Eﬀects of carbon-ion irradiation to male gametes on double
fertilization in Cyrtanthus mackenii
T. Hirano,∗1,∗2 Y. Watarikawa,∗1,∗3 Y. Hayashi,∗2 T. Abe,∗2 and H. Kunitake∗1
Heavy-ion-beam mutagenesis has been applied forvarious plant materials, and many mutants have beensuccessfully obtained through the screening process.
As one of the plant materials for the irradiation, pollen
was used for mutant induction.1,2) When pollen grains
of Cyrtanthus mackenii (Amaryllidaceae) were irradiated with a carbon-ion beam, inhibitory eﬀects onpollen tube growth were not observed.3) It is reported
that generative cells in the irradiated pollen grains
can recognize and manage genomic lesions using DNA
damage response pathways during pollen tube growth.
However, with high-dose irradiation (40 Gy), sperm
cell formation is prevented and the generative cells are
not divided into two sperm cells; however, the cell cycle
progresses. The male gametes are called generativecell-like sperm cells (GC-like SCs). In this study, we
analyzed the reproduction process involved in the irradiated pollen grains to reveal the behavior of malegametes during double fertilization.
Anthers of C. mackenii in 0.2-mL tubes were irradiated with C ions (22.5 keV/µm) at a dose of 10 or
40 Gy and then stored at −20◦ C. The pollen grains
with or without carbon ion beam irradiation werecrossed with unirradiated female organs. The ovules
were ﬁxed with an FAA solution (formaldehyde, acetic
acid, and ethanol) for 3 days after the crossing (DAC),
and we observed the developmental states of the ovules
by using the paraﬃn section method.
In the embryo sacs at 3 DAC with the unirradiatedpollen grains, a degenerated synergid cell, an undivided egg, and central cells were observed. In the sexual reproduction process of higher plants, one of thesynergid cells, which succeed in interacting with thepollen tube, is degenerated. Therefore, it is indicatedthat the pollen tubes reached one of the synergid cells
until 3DAC, and the embryo sacs were considered immediately before or after fertilization. In addition to
the embryo sacs at the fertilization phase, we observed
abnormal embryo sacs without the egg apparatus andcentral cell (Fig. 1). The proportions of the embryosacs in the fertilization phase, abnormal development,
and unfertilization were 79%, 9%, and 12%, respectively.
In the pollen grains irradiated at 10 Gy, pollen tubes
also arrived at the embryo sacs until 3 DAC. The proportions of the embryo sacs in the fertilization phase,abnormal development, and unfertilization were 79%,
∗1
∗2
∗3

Fig. 1. Abnormal embryo sac formed 3 days after the crossing with unirradiated pollen grains. The arrow indicates the abnormal embryo sac. The embryo sac on theleft side has a central cell. Bar = 50 µm.

6%, and 15%, respectively, and were the same as thatin the case of unirradiated pollen grains. After 40 Gy
irradiation, the proportion of embryo sacs in the fertilization phase was 58% and that in the abnormal development was 28%. These results indicated that pollen
tubes from the irradiated pollen grains also arrived at
the embryo sacs until 3 DAC.
Since the abnormal embryo sacs were commonly observed with or without carbon-ion irradiation, the abnormal development is interpreted to be aﬀected byenvironmental factors or the plant status. Based on
the interpretation, the proportion of embryo sacs at
the fertilization phase is thought not to be drasticallydecreased in the pollen grains irradiated at 40 Gy. It
is also suggested that inhibitory eﬀects on pollen tube
growth would not be observed in vivo. However, there
is a possibility that under high-dose irradiation, pollen
tubes or male gametes promote abnormal embryo sac
formation.
We are now observing embryo sacs after 14 DAC.
Those data are expected to reveal double fertilizationand the embryogenesis process involved in the irradiated male gametes and will be useful for understanding
abnormal embryo sac formation.
References

Faculty of Agriculture, University of Miyazaki
RIKEN Nishina Center
present aﬃliation: Agriculture and Forestry Technical Development Center, Nagasaki Prefectural Government- 214 -

1) K. Naito et al., Genet. 169, 881 (2005).
2) Y. Kazama et al., Sci. Rep. 6, 18917 (2016).
3) T. Hirano et al., AoB Plants 5, plt004 (2011).

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

Death of pollen tetrads caused by chromosomal rearrangement
Y. Kazama,∗1 H. Abe,∗1 K. Ishii,∗1 M. Sato,∗2 T. Hirano,∗3 K. Toyooka,∗2 and T. Abe∗1
Chromosomal rearrangements can be induced withhigh eﬃciency by using high-LET irradiation.1) They
are considered one of the important mutations during
evolution, because chromosomal rearrangements canaﬀect the gene expression patterns.2) On the other
hand, they sometimes cause a defect in the inheritanceof chromosomes, because of the loss of a large set of
essential genes (Fig. 1).
To observe such a defect of chromosome inheritance, we used an Arabidopsis T-DNA tagging mutant(SALK 123114), which was provided by the Arabidop-

sis Bio-Resource Center (ABRC). A whole genome
analysis followed by the mutation detection with
AMAP3) revealed a reciprocal translocation between
chromosome 1 and 2 in this mutant (Fig. 1). The TDNA was inserted in the junction region. We crossed
this mutant with another mutant (SALK 056345) totrace the inheritance of the chromosome by inserting
T-DNA in chromosome 2 of SALK 056345. In the F2generation, we detected only three types of chromosomes, namely wild type, F1 type, and SALK 123114
type (Fig. 1), and no double mutant had both T-DNA.
This result indicates that half of the zygote would bedead in the F1 plants. Indeed, about half of the pollens in the anthers of F1 plants were dead (data notshown), and about half of the seeds in siliques could
not mature in the F1 plants (data not shown), indicating that cell death occurred in both pollen and egg
developments.
From the whole genome mutation analysis, cells having pairs of a non-translocated chromosome and atranslocated chromosome were expected to be deadduring the development of pollens and eggs due tothe loss of large sets of genes. One pair lacked a partof chromosome 2, which contains 1,734,820 bp. The
other pair lacked a part of chromosome 1, which contains 5,804,110 bp. To determine the timing of the cell
death, we observed the pollen development in the F1plants. When TUNEL assay1, which can detect fragmentation of the DNA generated during cell death,
was performed, positive signals were detected in someof the tetrad cells in the F1 plants. This result indicates that the death of the pollen cells occurred justafter meiosis.

Fig. 2. Images of TUNEL assay in pollen tetrads.
Fig. 1. Ideogram of cell death occurring due to the genetic
cross of the rearrangement mutant.

References
∗1

∗2
∗3

1) Y. Kazama et al., Plant J. 92, 1020 (2017).
2) Y. Kazama et al., Cytologia 83, 125 (2018).
3) K. Ishii et al., Genes Genet. Syst. 91, 229 (2016).

RIKEN Nishina Center
RIKEN Center for Sustainable Resource Science
Department of Agriculture, Miyazaki University- 215 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

Estimation of eﬃcient dose for heavy-ion beam mutagenesis bywhole-genome mutational analysis in Arabidopsis thaliana
K. Ishii,∗1 H. Ichida,∗1 S. Ohbu,∗1 and T. Abe∗1
Heavy-ion beams are used as an eﬀective mutagen
that induces localized mutations due to its higher linear energy transfer (LET). The observation of the occurrence ratio of albino mutants as the mutation frequency
in the M2 generation after carbon-ion beam irradiation(30 keV/µm) at doses of 50–500 Gy showed that the
mutation frequency increased with increasing dose between 50–350 Gy and plateaued at 400 Gy.1) However,
the measurement of mutation frequency by visual screening of mutants from a large number of irradiated plants
is time-consuming. In this study, we tried to estimate
an eﬃcient dose for heavy-ion beam mutagenesis by performing whole-genome mutational analysis on relatively
small numbers of irradiated plants.
Dry seeds of Arabidopsis thaliana (the Col-0 strain)
were irradiated with 12 C6+ (135 MeV/nucleon) ions, atdoses of 0–350 Gy. The LET of C ion beams was controlled to 30 keV/µm. M2 seeds were harvested from selfpollinated M1 plants, and ten M3 plants were harvested
from one self-pollinated M2 plant. Genomic DNA wasextracted from the mixture of leaves of the ten M3 plants.
Five DNA pools were sequenced for each dose using
HiSeq X-Ten sequencing systems (Illumina Inc.). The
read sequences obtained were input into the mutational
analysis pipeline AMAP, as described previously, withsome modiﬁcations.2) In short, after mapping the readsequences to the reference genome sequence (TAIR10)
with BWA (BWA-MEM) software, the mutation candidates were detected with GATK (HaplotypeCaller),
PINDEL, and BREAKDANCER software. Then, theAMAP ﬁltered out the false-positives by using its own
algorithm.
In spite of the process of ﬁltering out false-positives,
conﬁrmation of the mutation candidates in one DNApool (350-Gy irradiation) by using Integrative Genomics Viewer (IGV) software revealed that 81% of
the candidates were still false-positives (data not shown).
We conﬁgured additional criteria for the determinationof false-positives. Among the mutation candidates output from GATK, those with the ‘QUAL’ value (calculated by GATK) less than 150 or ‘MAPPING_QUAL’value (calculated by BWA) less than 60 were treated as
false-positives. Among the mutation candidates output
from PINDEL, those with the ratio of the number of readsequences supporting the mutation to that of mapped
read sequences less than 0.2 or with the number of reads
supporting the mutation less than 5 were treated as
false-positives. Among the mutation candidates output
from BREAKDANCER, those with the ratio of the number of read sequences supporting the mutation to thatof mapped read sequences less than 0.15 were treatedas false-positives. Also, among the mutation candidates∗1

RIKEN Nishina Center

Fig. 1. Average number of mutations. Five DNA pools wereanalyzed at each dose.

output from PINDEL or BREAKDANCER, two candidates
from diﬀerent DNA pools overlapping one another bymore than 80% of their regions were treated as falsepositives. By using IGV software, it was revealed that
21% of the candidates in the DNA pool (350-Gy) werefalse-positives after these additional ﬁltrations and that
9% of the positive mutations were ﬁltered out by theadditional ﬁltrations. The mutation candidates in all
DNA pools were tested with the additional ﬁltrations
and checked using IGV software.
The number of mutations per genome increased monotonically as the irradiation dose increased and did notplateau until 350 Gy (Fig. 1). In this study, it wassuggested that irradiation at 350 Gy is eﬃcient in therange of 0–350 Gy. Although the means for evaluating the mutation frequency in this study was diﬀerent
from that in the previous study,1) the tendency of increase in the mutation frequency in proportion to theirradiation dose was similar. The mutation analysis
method in this study covered all mutations in the wholegenome while the mutation analysis by visual screening covered only those in genes related to the development of chloroplasts. Because this method can determine
the type (single nucleotide substitution, deletion, insertion, inversion, or chromosomal rearrangement) and thesize of each mutation, the previous study revealed the
LET-dependent eﬀect for mutation induction: heavy-ion
beams with higher LET can induce chromosomal rearrangements or large deletions more frequently than thosewith lower LET.3) In this study, it was also revealed that
this method can be applied to the dose-dependent eﬀect
for mutation induction.
References

1) Y. Kazama et al., BMC Plant Biol. 11, 161 (2011).
2) K. Ishii et al., Genes Genet. Syst. 91, 4, 229–233 (2016).
3) Y. Kazama et al., Plant J. 92, 6, 1020–1030 (2017).

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RIKEN Accel. Prog. Rep. 52 (2019)

Characterization of L-cysteine requiring mutants derived fromheavy-ion-beam irradiated cells in the unicellular green alga
Parachlorella kessleri
T. Yamazaki,∗1,∗2 E. Kounosu,∗1 T. Takeshita,∗1,∗2,∗3 A. Hirata,∗1,∗3,∗4 S. Ota,∗1,∗2 Y. Kazama,∗5 T. Abe,∗5 and
S. Kawano∗1,∗2,∗3
Many microalgae show accumulation of neutral lipids,
such as triacylglycerols (TAGs), in oil bodies under conditions in which there is a lack of nutrients, including nitrogen, phosphorus and sulfur, in their environment. Although sulfur starvation in microalgae induces lipid accumulation, little is known about the underlying mechanism. Interest in this phenomenon is divided into two
aspects: 1) the connection between recognition of sulfur
starvation and lipid synthesis and 2) whether the mechanism of lipid induction under sulfur-starvation conditions is shared with those of other nutrient-starvation
conditions. To answer these questions, we obtained
heavy-ion-beam irradiated algal mutants that require Lcysteine, which is an amino acid with sulfur.1)
Sulfate is the most highly oxidized sulfur compound,is widespread in nature and is the most important supplier of sulfur for green plants, including microalgae(Fig. 1A). Plants incorporate sulfate intracellularly asa sulfur source. In green algae and land plants, sulfate is taken up by the sulfate transporter (SULTR)
across the plasma membrane. Sulfate in the cytosol
is transported into chloroplasts by chloroplast localized
SULTR. In chloroplasts, sulfate is bound to ATP by sulfate adenylyltransferase (ATS) and deoxidized to sulﬁteby adenylyl-sulfate kinase (APSK) and adenyl sulfate
reductase (APR). Sulﬁde is reduced by sulﬁde reductase (SiR) and ﬁnally assimilated into L-cysteine by exchanging sulﬁde with the acetyl group of O-acetyl-Lserine (OAS) in a reaction catalyzed by O-acetylserine(thiol) lyase (OAS TL). L-cysteine is metabolized to Lmethionine through L-homocysteine in chloroplasts andmitochondria.2) Although knowledge of the microalgalsulfate-assimilation pathway is limited, the homologous
genes that function in sulfate assimilation in land plants
have been identiﬁed in Chlamydomonas.
Chlorella and Parachlorella species are unicellular immotile green microalgae classiﬁed in the Trebouxiophyceae, which have spherical cells less than ∼ 10 µm
in diameter containing a chloroplast. Parachlorella
kessleri accumulates TAG under sulfate-limited conditions.3) Therefore, this species can be used as a model
for investigation of the response to nutrient starvation.
We reported an investigation of the regulatory system oflipid and starch synthesis under sulfate-starvation con∗1
∗2
∗3
∗4
∗5

Department of Integrated Biosciences, Graduate School of
Frontier Sciences, University of Tokyo
JST, CREST
Future Center Initiative, University of Tokyo
Bioimaging Center, Graduate School of Frontier Sciences, University of Tokyo
RIKEN Nishina Center

Fig. 1. Sulfur-assimilation pathway and isolated Srp mutants ofP. kessleri. (A) Schematic of the sulfate assimilation pathway.
WT, wild type (B) Phenotype of Srp mutants.

ditions,1) and summarize it in this report.
Mutagenesis of P. kessleri was performed according
to our previous method. For isolation of cysteine requiring P. kessleri mutants using Fe-ion treatments, 200 µL
aliquots of a 2-day-old P. kessleri culture were transferred into tubes. The samples were stored at 4◦ C prior
to being subjected to heavy-ion-beam irradiation. Cells
were irradiated in the RIKEN RI-beam factory (Wako,
Saitama, Japan) at doses of 25 and 50 Gy. The linear
energy transfer value was 790 keVµm−1 . The irradiated cells were spread onto L-cysteine medium 1.5% agar
plates for isolation of single colonies. Approximately
13,000 colonies were picked as isolates and inoculated
onto both L-cysteine medium 1.5% agar plates and sulfate medium 1.5% agar plates. Isolates that grew onlyin L-cysteine were identiﬁed as sulfate repressed proliferation (Srp) mutants (Fig. 1B). The strains were deposited in the National Institute of Technology and Evaluation, Tokyo, Japan, under accession numbers FERM
BP-22268 (for Srp 1) and FERM BP-22288 (for Srp 2).
A phenotype of these mutants under sulfate replete
conditions exhibited that cell proliferation was suppressed like the phenotype of wild type under sulfur
deplete conditions, but starch was highly accumulated.
The eﬀects of sulfate and L-cysteine on lipid and starch
accumulation in the wild type and mutants were compared in media containing diﬀerent sulfur compounds
as sulfur sources. Our results suggest that a shortageof L-cysteine, which is a metabolite of sulfate, induces
lipid accumulation and that sulfate ions promote starch
accumulation in chloroplasts. This study was supported
by JST, CREST and START (to SK).
References
1) Condensed from the article in Yamazaki et al., Algal Res.
36, 37–47 (2018).
2) Ravanel et al., J. Biol. Chem. 279, 22548–22557 (2004).
3) Takeshita et al., Bioresource Technol, 158, 127–134 (2014).

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RIKEN Accel. Prog. Rep. 52 (2019)

Increase of lipid production upon outdoor cultivation of heavy-ion beamirradiation mutant Parachlorella kessleri PK4 and identification of its
genetic variations†
T. Takeshita,∗1 K. Oshima,∗2,∗3 K. Ishii,∗4 H. Kawamoto,∗1 S. Ota,∗1,∗3 T. Yamazaki,∗1,∗3 A. Hirata,∗5
Y. Kazama,∗4 T. Abe,∗5 M. Hattori,∗2,∗3 and S. Kawano∗1,∗3
In recent years, microalgae have gained signiﬁcant attention as a promising feedstock for the biofuel industry.
Some microalgae such as Parachlorella kessleri, a species
separated from the genus Chlorella, can accumulate highlevels of starch and lipids that can be used for the production of bioethanol and biodiesel, respectively.1,2) Irradiation of P. kessleri with heavy-ion beams with varying doses and ion species resulted in the generation ofphenotypes with potential economic relevance in termsof lipid production.3) One such mutant, PK4, exhibitedhigh lipid accumulation under nitrogen starvation conditions.3)
In this study, the lipid accumulation of PK4 was analyzed using two experimental systems: a laboratorybased small-scale culture and thin-layer photobioreactor(T-PBR) mass cultivation in a culture volume of 150 l.
Nutrient dilution was adopted to maximize the lipid productivity by exploiting the PK4 response to nutrient
limitation. We also determined its genetic variation bywhole genome re-sequencing.
TAP and UP media were compared to maximize thelipid productivity of PK4 at a laboratory scale (80 ml).
The growth of wild type (WT) and PK4 stopped in thecomplete TAP media on day 6 post-inoculation, but both
WT and PK4 continued to proliferate in the UP media
even on day 8 post-inoculation. In the complete UP
media, only a small amount of lipid accumulated in either WT or PK4 cultures. The culture on day 4 postinoculation was collected and diluted with sterilized distilled water and individual cultivations were continued.
PK4 accumulated more lipids and at an earlier stage
than WT in UP medium after nutrient dilution.
The nutrient dilution experiment was performed in a
150 l thin layer- photobioreactor (T-PBR) (Fig. 1). The
culture was diluted with water four times to induce nutrient limitation on day 7 post-inoculation. Lipids began
to increase from day 9 post-inoculation (2 days after dilution) and continued to increase until the last day ofcultivation (38% DW, 2.0 g · L−1 ). The maximum lipid
content was 66% per dry weight (Day13, 2.9 g · L−1 )and the maximum lipid productivity after dilution was
0.59 g · L−1 · day−1 .
The locations of genetic variation in PK4 were inves†

∗1
∗2
∗3
∗4
∗5

Condensed from the article in Algal Res. 35, 416–426 (2018)
Department of Integrated Biosciences, Graduate School of
Frontier Sciences, University of Tokyo
Center for Omics and Bioinformatics, Graduate School of
Frontier Sciences, University of TokyoJapan Science and Technology Agency (JST), CREST
RIKEN Nishina Center
Bioimaging Center, Graduate School of Frontier Sciences, University of Tokyo

Fig. 1. Time-series data in T-PBR. (A) water temperatureand light intensity, (B) cell numbers and biomass, and(C) content of starch and lipids. The culture was diluted
with water four times on day 7 post-inoculation.

tigated by next-generation sequencing (Illumina MiSeq
and HiSeq). In total, we identiﬁed three loci, which
probably caused the observed phenotype in the automated mutation analysis pipeline (AMAP) with somemodiﬁcations.4) They correspond to putative homologs
of elicitor-responsive protein (9934_t), ATP/ADP transporter (9067_t) and endo-1,4-β-mannanase (8741_t).
There are three copies of the 9067_t gene in the genome.
One of the three homologs is ATP and ADP transporter
localized in the chloroplast envelope. However the relationship of this transporter with membrane lipids has
been discussed.5) The 8741_t gene has 13 genetic copies.
Mannan is one of the polysaccharides present in thecell wall of algae.6) 1,4-β-mannanase hydrolyzes β-1,4mannosidic linkages of D-mannan, as well as galacto- andglucomannans at random site.7) A study of metabolites
or genetics including complementation of the aﬀected
genes would be required to determine the gene(s) whose
mutation is responsible for the PK4 phenotype.
References

1) B. Fernandes et al., Bioresour Technol. 144, 268–274(2013).
2) X. Li, et al., Biotechnol Bioeng. 110, 97–107 (2013).
3) S. Ota et al., Bioresour Technol. 149, 432–438 (2013).
4) K. Ishii et al., Syst. 91, 229–233 (2017).
5) A. G. Navarro et al., J. Cell. Physiol. 229, 2126–2136(2014).
6) H. Takeda et al., Phytochemistry 34, 1053–1055 (1993)
7) Do Bien-Cuong et al., Factories 8, 59 (2009).

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Pleiotropic mutant of plant-symbiotic edible mushroom Tricholoma
matsutake induced by argon-ion beam†
H. Murata,∗1 T. Abe,∗2 H. Ichida,∗2 Y. Hayashi,∗2 T. Yamanaka,∗1 T. Shimokawa,∗1 and K. Tahara∗1
Tricholoma matsutake is an ectomycorrhizal fungus
that produces prized mushrooms “matsutake” in association with conifers.1) Currently, there are no fungal strains as useful in cultivating fruits as commercial
saprophytic edible mushrooms. Developing the strainsthat are suitable for spawn cultivation will greatly
contribute to the artiﬁcial cultivation of mycorrhizal
mushrooms. Previously, we reported that an argonion beam (40 Ar17+ , 95 MeV/nucleon) eﬃciently killed
T. matsutake strains on agar plates at a dose of over
100 Gy and generated some mutants whose mycelial
morphology was diﬀerent from that of the wild-type.2)
In this study, we document that the irradiation ofargon-ion beam on T. matsutake induces a mutant thathas pleiotropically altered phenotypes in mycelial morphology and degrading enzymatic activities.
The mutant Ar 59 was obtained by irradiating themycelia of T. matsutake NBRC 33136 on modiﬁed
Melin-Norkrans agar containing 1.5% V8 juice withan argon-ion beam at a dose of 500 Gy. Next, themycelial colony was separated into pieces and transferred onto fresh agars.2) The Ar 59 strain formed
a hedgehog-like colony on the potato dextrose agar
(PDA) containing 0.1% azurin-crosslinked (AZCL)amylose and 0.1% AZCL-hydroxyethyl (HE)-cellulose
substrates, unlike the wild-type strain that had a ﬂatmycelial mat with ﬂower-like areal hyphae on the inoculation plug (Figs. 1 (a–d)). The Ar 59 strain exhibited a signiﬁcantly higher amylose- and cellulosedegrading activities than the wild-type strain. In addition, clear halo zones, resulting from the conversionof water-insoluble dye-linked substrates into water soluble substances, were formed around the colonies during the incubation period of 21 days. These clear halozones extended for seven additional days (Figs. 1 (e–h)).
The phenotype of strain Ar 59 diﬀered substantiallyfrom those of T. matsutake NBRC 33136, which raises
a concern whether Ar 59 is a contaminant. Therefore,
the relationship between the NBRC33136 and Ar 59
strains was clariﬁed by analyzing the sequences of theirrRNA gene ITS (867 bp) and IGS1 (361 bp) regions,and the phylum-speciﬁc mobile DNA megB1 (479 bp).
The results showed that the strain sequences were identical. Therefore, strain Ar 59 was proven to be a mutant of T. matsutake NBRC33136.
We have isolated a pleiotropic mutant whose colonymorphology diﬀers from that of the wild-type T. mat†∗1
∗2

Fig. 1. Traits of T. matsutake mutant Ar 59 on PDA containing AZCL-amylose and AZCL-HE-cellulose. (a–d)
Colony morphology. (a, c) NBRC 33136 on PDA containing AZCL-amylose and AZCL-HE-cellulose, respectively. (b, d) Strain Ar 59 on PDA containing AZCLamylose and AZCL-HE-cellulose, respectively. (e–h)
Depolymerizing activities. (e, g) NBRC 33136 on PDA
containing AZCL-amylose and AZCL-HE-cellulose. (f,h) Strain Ar 59 on PDA containing AZCL-amylose
and AZCL-HE-cellulose, respectively. Clear halo zones
around the colonies were scored as enzymatic activities(e–h).

sutake strain NBRC33136 and has acquired high levels of amylose- and cellulose-degrading activities. Its
pleiotropic feature indicates that argon-ion beams may
have deleted a part of negative regulatory region that
controls various traits. Whether heavy-ion beams thatbreak double-stranded regions of DNA ranging in size
from a few bp to over 1 kilobase positively inﬂuence
the life cycle of fungus, rendering fruiting in spawn
cultivation, remains to be clariﬁed. However, irradiation with heavy-ion beams may be useful to create newtraits in T. matsutake.
References
1) A. Yamada et al., Mycoscience 55, 27 (2014).
2) H. Murata et al., RIKEN Accel. Prog. Rep. 51, 244(2018).

Condensed from the article in Mycorrhiza 28, 171 (2018)
Forestry and Forest Products Research Institute
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Comparison of biological eﬀect between low- and high-LET irradiation
on DSB repair in the ﬁlamentous fungus Neurospora crassa †L. Ma,∗1,∗2,∗3 Y. Kazama,∗2 T. Hirano,∗2,∗4 R. Morita,∗2 S. Tanaka,∗1 T. Abe,∗2 and S. Hatakeyama∗1
Ionizing radiations induce various cellular injuries, especially DNA double-strand breaks (DSBs). To obtaininsights on the biological eﬀects on several forms of ionizing radiations causing DSBs, we examined the cell killingeﬀect, mutation frequency, and mutation type proﬁle us1,2)
ﬁlamentous fungus Neurospora crassa.1)
ing the model filamentous
Two repair pathways, homologous recombination(HR) repair and non-homologous end-joining (NHEJ),
recognizes and processes DSBs to maintain the integrityof genetic information. Asexual spores of wild-type
Neurospora crassa and two DSB repair-deﬁcient mutants (NHEJ-related mus-52 knockout strain and HRrelated mei-3 nonsense mutant) were irradiated with
X-ray (200 kVp, 2–5 keV/µm) as a low-linear energy transfer (LET) beam, and C- (135 MeV/nucleon,
30 keV/µm), Ar- (95 MeV/nucleon, 287 keV/µm), andFe- (90 MeV/nucleon, 641 keV/µm) ion beams as highLET beams. The survival rates were examined by acolony formation assay. Mutagenesis frequencies at ad-3loci were calculated as a ratio of visual purple colonies
to total colonies. Mutation spectra at the ad-3B gene ofcollected mutants were examined by DNA sequencing.
The experimental schema is shown in Fig. 1.
To determine the relative biological eﬀectiveness(RBE) values on the killing eﬀect, the doses with 50%
survival in each ion-beam irradiation were comparedwith those obtained after X-ray irradiation as the reference radiation. RBEs of C-, Ar-, and Fe-ion beams were
calculated to be 3.0, 7.4, and 5.8, respectively. Therefore, the Ar-ion displayed the greatest lethal eﬀect on
Neurospora crassa, which was found to be 2.5 times more
eﬀective than the C-ion. The rank order of RBE was Ar> Fe- > C-ion> X-ray.
C- > X-ray.
The killing eﬀect proﬁle of the X-ray irradiation wasquite similar to the C-ion beam. The mus-52 strain exhibited sensitivity to X-ray similar to that observed in
the mei-3 strain at 100 Gy. However, little additional
cell death was observed at 200, 300, and 400 Gy. The
survival rate in response to the high-LET ion-beam irradiation progressively decreased with the absorbed dose
for all irradiated strains. In the case of C-ion beam irradiation, the sensitivity of the mus-52 strain was higher
than that of the wild-type and mei-3 strains at low
doses. In the case of Ar-ion beam irradiation, the mei-3
strain exhibited the highest sensitivity at all doses. In
the case of Fe-ion beam irradiation, the survival curves
†
∗1
∗2
∗3
∗4

Condensed from the article in Int. J. Radiat. Biol. 94, 1125–
1133 (2018)
Laboratory of Genetics, Faculty of Science, Saitama University
RIKEN Nishina Center
Gunma University Heavy Ion Medical Center
Faculty of Agriculture, University of Miyazaki

Fig. 1. Experimental schema of biological eﬀect evaluation.

of three strains did not diﬀer at lower doses, whereas obvious diﬀerences in sensitivity (mei-3 > mus-52 >WT)
were observed at higher doses.
The mutation frequency in the ad-3 loci indicated thatmei-3 > wild type > mus-52 in all irradiated beams.
The Ar-ion beam demonstrated a higher mutagenic capability than the Fe-ion beam in both the wild-type andmei-3 strains. The mutation frequency of the wild-typestrain was lower in response to Fe-ion beams than the Xrays. The deletion mutations were the most frequent but
the deletion size increased with the increasing value of
LET. The high-LET ion beams tended to induce larger
deletions, with Fe-ion beams inducing deletions > 100 bp
and Ar-ion beams causing deletions that ranged from 2
to 100 bp. Alternatively, low-LET X-ray induced deletions of 1 bp.
Our results indicated that high-LET ion beams exhibit higher cell killing and increased deletion size than
low-LET X-ray in Neurospora crassa. These diﬀerent
LET-dependent phenomena may be due to the physicalproperties of each radiation and repair mechanism of thedamage induced in Neurospora crassa. Our results may
be useful in selecting the appropriate beam source tomutagenize fungi for further research and agricultural
applications. For example, C-ion beams, which predominantly cause single-nucleotide deletions and baseexchanges but few large deletions compared with higherLET Ar- and Fe-ion beams, may be useful in generating novel fungal strains harboring mutation in essential
genes without destroying the neighboring genes.
Reference
1) L. Ma et al., Fungal Biol. 117, 227–38 (2013).

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Eﬀect of diﬀerent conditions of the mutant isolation system on rotifers
by using heavy-ion beam irradiation
K. Tsuneizumi,∗1 M. Yamada,∗1 K. Ichinose,∗1 H. Ichida,∗1 and T. Abe∗1
Heavy-ion beam mutagenesis is generally recognized
as an eﬀective method for mutation breeding.1,2) Although this method has been greatly successful withplants, its application to animals is limited. Therefore,
we plan to acquire more basic data to set up the optimal conditions for a heavy-ion beam irradiation system
by using Brachionus plicatilis sensu stricto (rotifer) as
the model.3)
In aquaculture, rotifers are used as the live bait forlarval ﬁshes that have just been born. As larval ﬁshes
grow, they select food based on the mouth size.4) Rotifers are used for larval ﬁshes at ﬁrst, and later on
the brown shrimp Artemia is used. Rotifers averagearound 300 µm in length, while Artemia is between
400 µm and 1 cm in length. When switching foodfrom rotifer to Artemia, a live bait of a suitable size
(300–400 µm) has not been found yet. During thisgap time, larval ﬁshes die of starvation or cannibalize
each other, and these problems result in a signiﬁcantdecrease in the number of larval ﬁshes. It is known to
be a common bottleneck in aquaculture.
In this study, to overcome the problem of starvation and cannibalization, we plan to establish large rotifers required during the gap time. Using heavy-ion
beams accelerated by the RIBF accelerator at RIKEN,
we measured the biological eﬀect of heavy-ion beamirradiation on rotifers under diﬀerent conditions. After irradiation, each rotifer was separated to a plastic
culture dish and cultivated at 20◦ C at a salinity of
1.8%. Nonirradiated rotifers almost survived throughthe experiment. On the contrary, the survival rate ofrotifers irradiated by 600 Gy of carbon-ion beam wasdecreased to 41.7% by the 16th day after irradiation(Fig. 1). The survival rate of rotifers irradiated by
200 Gy of argon-ion beam was decreased to 15.0% by
the 15th day after irradiation (Fig. 2). The survival
rate decreased gradually depending on the degree ofirradiation dose (Figs. 1, 2). These data will be helpful for the establishment of the mutant isolation systemby heavy-ion beam irradiation on rotifers.

Fig. 2. Eﬀects of diﬀerent argon irradiation conditions on
survival rate of rotifers. The rotifers were irradiatedwith argon-ion beams at diﬀerent dose levels (25, 50,
75, 100, 150, and 200 Gy). The survival rates were
measured every two or three days under each condition
after irradiation. The data includes mean ± SE of six
independent experiments. The bars represent the SE ofdata.

References
Fig. 1. Eﬀects of diﬀerent carbon irradiation conditions on
survival rate of rotifers. The rotifers were irradiatedwith carbon-ion beams at diﬀerent dose levels (100, 150,
200, 300, 400, and 600 Gy). The survival rates were
measured every two or three days under each condition
after irradiation. The data includes mean ± SE of six
independent experiments. The bars represent the SE of
data.
∗1

RIKEN Nishina Center- 221 -

1) T. Abe et al., in Plant Mutation Breeding and Biotechnology, edited by Q. Y. Shu et al., (CABI, Oxfordshire,2012).
2) A. Tanaka et al., J. Radiat. Res. 51, 223 (2010).
3) S. Mills et al., Hydrobiologia 796, 39 (2017).
4) Y. Sawada et al., Bull. Fish. Lab. Kinki Univ. 7, 1
(2000).

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

The inhibitor of DNA-PK suppressed DNA repair after heavy-ion
irradiation in quiescent mammalian cells∗1

RIKEN Nishina Center

X log
X G0
C log
C G0

40
30
20
10
0

01 3

8
16
time from irradiation (h)24Fig. 1. The number of phosphorylated histone H2AX fociafter irradiation. NB1RGB cells were synchronized in
the quiescent state by serum starvation for 48 h. Cells
in the proliferating state (◦ △) or quiescent state (• )were irradiated with 5 Gy of X-ray or carbon ions (LET
= 80 keV/µm), and the phosphorylated histone H2AX
was detected by immunostaining 1–24 h post irradiation.

30
25

Number of phosphorylated
histone H2AX foci/cell

Accelerated heavy-ion particles with high linear energy transfer (LET) induce complex clustered DNA
damage, which is an obstacle to eﬃcient repair. DNA
double-strand breaks (DSBs) are most lethal damage among them and are repaired primarily by nonhomologous end joining (NHEJ) or homologous recombination (HR) in mammalian cells, whereas alternative NHEJ (alt-NHEJ) and/or single strand annealing(SSA) work only when both NHEJ and HR are impaired.
Several published studies using the Chinese hamster
ovary (CHO) cells and two CHO mutant lines deﬁcientin HR or NHEJ suggest that NHEJ does not eﬃciently
repair DNA damages and that HR is essential for survival after heavy-ion irradiation.1,2) On the other hand,a study using inhibitors against NHEJ and HR in human lung cancer cell line suggests that NHEJ is a major DNA repair pathway after heavy-ion irradiation.3)
Therefore, the DNA repair mechanism is still controversial in higher eukaryotes.
In this study, we investigated the repair mechanism inquiescent mammalian cells, where HR does not work.
To estimate the secondary carcinogenesis in radiation
therapy, it is important to know whether DNA damages
are repaired by NHEJ or highly mutagenic alt-NHEJ
and/or SSA, because the majority of the cells in the
body exist in a quiescent state. First, we investigated
the foci formation of phosphorylated histone H2AX,
which reﬂects the presence of DSBs after irradiation(Fig. 1). The number of histone H2AX foci reachedmaximum immediately after X-ray or carbon ion irradiation and decreased similarly as time proceeded in both
logarithmically growing cells and quiescent cells. These
results suggest that NHEJ is a major repair pathway inboth logarithmically growing cells and quiescent cells
since HR does not work in quiescent cells and requiresa much longer time (> 8 h) than NHEJ.
To conﬁrm that NHEJ is a major pathway in quiescent cells, we investigated the eﬀect of NU7441, a
potent speciﬁc inhibitor of DNA-PK, which is involvedin NHEJ (Fig. 2). NU7441 increased the number ofphosphorylated histone H2AX 16 h after carbon ion irradiation, suggesting that NHEJ is the dominant DNA
repair pathway. It is also suggested that alt-NHEJ or
SSA does not work eﬃciently in quiescent cells.
In the previous report, we have shown that the cell
survival of CHO cells is dependent on HR4) as several
groups have already reported.1,2) HR may play a majorrole in DNA repair in CHO cells because CHO cells
are not arrested in the G1 phase and accumulate in
the S-G2 phase after irradiation due to the lack of p53

Number of phosphorylated
histone H2AX foci/cell

M. Izumi∗1 and T. Abe∗1

20
15
10
5
0

1

16
0

1

16
3

(h)
NU7441 (µM)

Fig. 2. The eﬀect of NU7441 on DNA repair. The quiescentNB1RGB cells were treated with 3 µM NU7441 and irradiated with 2 Gy of carbon ions, and the phosphorylated
histone H2AX was detected 16 h post irradiation.

(data not shown). On the contrary, the majority oflogarithmically growing NB1RGB cells (60–70%) are in
the G1 phase and stay in the G1 phase until DSB repair
is completed. Therefore, NHEJ may play a major role
in DNA repair in NB1RGB cells. Currently, we are
examining the eﬀect of drugs on several cell lines toinvestigate whether the genetic background can explain
the selection of repair pathways.
References

1) 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) M. Izumi, T. Abe, RIKEN Accel. Prog. Rep. 47, 253(2014).

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Phosphorylation and accumulation of low-dose high-LET heavy
ion-induced bystander signaling molecules
M. Tomita,∗1,∗2 T. Tsukada,∗2 and M. Izumi∗2
Radiation-induced bystander response (RIBR) is acellular response induced in non-irradiated cells thatreceived bystander signals from directly irradiatedcells.1) RIBR induced by low doses of high-linear energy transfer (LET) radiation is an important issue forthe health of astronauts and in hadrontherapy. Here,
we investigated the underlying molecular mechanisms
and biological implications of high-LET RIBR.
We found that normal human ﬁbroblast WI38, cultured conﬂuent, irradiated with high-LET(1000 keV/µm) iron (Fe) ions showed the bystander
cell killing eﬀect at low doses (≤ 0.2 Gy).2) In addition,
we reported that gap-junction intercellular communication (GJIC), cyclooxygenase-2 (COX-2), and nitricoxide (NO) were involved in its signal transfer.3)
Figure 1 shows the phosphorylation and accumulation of bystander signaling related molecules in WI-38
cells irradiated with 0.1 Gy of Fe ions. Cells were pretreated with or without c-PTIO (a scavenger of NO)or lindane (an inhibitor of GJIC). Left panels werepreviously reported.4) The phosphorylation of Akt at
Ser473 and NF-κB p65 at Ser536 and accumulation of
COX-2 were observed in the cell 3 h after irradiation.
They were eﬃciently inhibited by c-PTIO. Phosphorylated histone H2AX at Ser139 (γ-H2AX) is widely used
as a surrogate marker of DNA double-strand breaks(DSBs). γ-H2AX was observed 3 and 6 h after irra-

diation and the one at 6 h was inhibited by c-PTIO.
These results suggest that phosphorylation of NF-κB,
Akt, and histone H2AX and accumulation of COX-2
were mainly mediated by NO. Meanwhile, phosphorylation of Akt at 3 h after irradiation was also inhibitedby linedane but that of NF-κB and γ-H2AX was not(right panels). Surprisingly, COX-2 was overexpressedin the cells pretreated with lindane irrelevantly to irradiation. It is well known that COX-2 overexpressedcancer cells are resistant to the induction of apoptosis.5) The ability of lindane to inhibit GJIC is apparent,1) whereas COX-2 overexpression in addition to inhibition of Akt may also contribute to the inhibitionof bystander cell killing, even if DSBs are induced in
the bystander cells.
Continued studies must elucidate the role of GJIC.
The obtained results suggested that NF-κB, Akt, andCOX-2 were involved in the low-dose of high-LET
heavy-ion-induced bystander signaling.
References
1) M. Tomita, M. Maeda, J. Radiat. Res. 56, 205 (2015).
2) M. Tomita et al., RIKEN Accel. Prog. Rep. 48, 302(2015).
3) M. Tomita et al., RIKEN Accel. Prog. Rep. 50, 266(2017).
4) M. Tomita et al., RIKEN Accel. Prog. Rep. 51, 234(2018).
5) M Tsujii, R. N. DuBois, Cell 83, 493 (1995).

Fig. 1. Phosphorylation and accumulation of bystander signaling related molecules. WI-38 cells werepretreated with or without c-PTIO (20 µM) or lindage (Lin, 50 µM) 2 h before irradiation with
0.1 Gy of 90 MeV/nucleon Fe ions (1000 keV/µm). Cells were harvested 3 and 6 h after irradiation
followed by immunoblotting.
∗1∗2

Radiation Safety Research Center, Central Research Institute of Electric Power Industry
RIKEN Nishina Center- 223 -

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CR-39 imaging method to estimate microbeam profiles produced bytapered glass capillary optics
Y. Hikima,∗1,∗2 T. Ikeda,∗1,∗2 M. Ikekame,∗1,∗2 M. Mori,∗1,∗2 S. Kawamura,∗1,∗2 T. Minowa,∗2 and W. -G. Jin∗2
To perform accurate ion microbeam irradiation on biological targets, such as the nucleus of a mammalian cell,
bacterium, and a small organ of an insect, the beam
proﬁles should be quantitatively estimated to obtain the
narrowest beam spot. We employed tapered glass capillary optics with an end-window at the thin outlet to
produce microbeams of MeV ions. This optics realizes
the irradiation whose target is even in air or liquid. The
beam structure produced by the capillary optics was already reported to have core and halo components.1) The
ions without any scattering on the inner glass wall maintain their initial directions and generate a sharp spot
known as the core. The other ions suﬀering from thescattering may form a broad spot, which is called a halocomponent. The halo component should be suppressedto obtain narrower beam size, thereby resulting in good
position resolution for irradiation experiments.
A plastic tracking detector CR-39 is available for theobservation of microbeam proﬁles, where the ion hitting
point appears as a pit with a diameter of a few µm afteretching with, for example, 7N-NaOH for 2 h. However,the standard CR-39 detector is not suitable for H ionsowing to low linear energy transfer (LET). In this study,a CR-39 with higher sensitivity, whose product name is
HARZLAS, was employed. Although it is generally diﬃcult to implement the analysis of pit distribution createdby microbeam because the pits in the spot overlap eachother, the parametrization of the halo component can befree from overlapping. Here, we report an analysis of the
microbeam proﬁles of H ion with an energy of 2.8 MeV
to aim at a small-sized spot (several tens of µm) at an
irradiation distance of 1 mm or divergence of 1◦ .
We have started the trial of using the brightness (darkness) information of each unit area in a microscopic
photo of a piece of CR-39 as the density of the pits, assuming that all pits are separated and are approximately

Fig. 1. (a) 2.8 MeV H+ microbeam spot on CR-39 and thehistogram along with slice area. (b) Ion energies after
transmitting the materials estimated by SRIM simulation.
No ions were transmitted through more than five layers.
∗1∗2

RIKEN Nishina Center
Department of Physics, Toho University

Fig. 2. Spot sizes according to the number of Al layers withthickness of 11 µm. Panel (e) shows the narrowest spot.

of the same size. This method cannot be implemented
to the center of the core. However, it can be possibly
applied to the halo component and the region outlining
the core. An H+ beam accelerated by the RIKEN Pelletron accelerator was transmitted through a capillarywith an outlet of 9.9 µm. Then, a spot was formed ona piece of CR-39 at an irradiation distance of 1 mm,
which is shown in the upper panel of Fig. 1 (a). The
green histogram in the lower panel expresses the sum of
darkness along with a horizontal thin zone shown as the
slice area in the upper panel. The histogram was analyzed to have two Gaussian peaks with 176 and 575 µm in
FWHM corresponding to the core and halo component,
respectively. However, the core size is not used in further
analysis because the darkness density at the center is already saturated. The ions in the halo component had
relatively lower energies, which can be stopped if Al layers with a thickness of 11 µm are inserted. Figure 1 (b)shows the decline of ion energy as the layers were added
according to the SRIM simulation.2) Figure 2 shows thebeam spots and the histograms showing the spot sizes.
As shown in Fig. 2 (e), the narrowest spot was obtainedwith four layers. The energy of ions was estimated to be
1.08 MeV with a standard deviation of 52 keV regarding
the simulation. This method can determine the accurate
number of Al layers to obtain the narrowest spot.
References

1) J. Hasegawa et al., J. Appl. Phys. 110, 044913 (2011).
2) Simulation code, SRIM-2003, http://www.srim.org/ .
- 224 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 52 (2019)

Stability test of ion microbeams produced by tapered glass capillary
optics for biological use
T. Ikeda,∗1 M. Hamagaki,∗1 M. Ikekame,∗1,∗2 Y. Hikima,∗1,∗2 and H. Sato∗1
Ion beam irradiation to cell nucleus has played an
important role in the induction of artiﬁcial damage inDNA. The extent or type of DNA damage depends on
the stopping power of the ion, which is a function ofion mass and velocity. For example, heavy ion cancer
therapy employs carbon ions. Ion beam breeding to produce mutants of plants uses C, Ar, and Fe ions and soon. Both cases use fast heavy-ions in the order of 10
to 100 MeV/nucleon to obtain a range varying between
a few mm and a few tens of cm and maintain a stopping power large enough to induce double-strand breaks(DSB) in DNA. To investigate a similar eﬀect in single cells, slow light-ions (H or He) with energy of a few
MeV are available. A He2+ ion with 4 MeV energy has
the range of approximately 20 µm in water, which islarger than the thickness of cells, and a stopping power
greater than 200 keV/µm, which is strong enough tocreate DSB.
Employing such H or He ions with energies of afew MeV provided by the Pelletron tandem accelerator(1.7 MV max.) in Nishina R&D Building, we developed
a microbeam irradiation system based on single tapered
glass capillary optics with a plastic end-window at thethin outlet. Figure 1 (a) shows an image of an approximately 7-cm-long glass capillary mounted at the beam
port of BL-W30. The capillary inlet/outlet diameters
were 1.8 mm/10 µm, respectively, and the thickness ofthe end-window at the outlet was 9 µm. The cylindrical object just downstream of the capillary was a PIN
photodiode assembly to count the ions.
Because we plan to perform single-ion irradiation to acell nucleus, the stopping power of the ions and the dose(number of ions in the target area) are critical factors. A
cell irradiation system, in particular, requires accurate
irradiation time and highly stable microbeam intensity.
However, the stability of Pelletron terminal (acceleration) voltage is not better than 0.5% and consequently,
the microbeam intensity was really unstable until the
beginning of 2018. The accelerated ions go through a series of quadrupole magnets (QM), a vertical steerer, anda switching magnet (SM), and enter the capillary optics
after travelling 5–6 m. The unstable terminal voltage results in the ﬂuctuation of the spot position. To stabilize
the number of ions entering the capillary, the beam was
defocused by QM. The beam proﬁle was monitored by an
Al2 O3 ﬂuorescent plate with a 5 mm interval grid connected to a pico-ammeter shown in Fig. 1 (b). The proﬁle monitor was installed at BL-W15, which is a beamline next to BL-W30. The monitor and the capillary
optics were at a similar distance from SM. Figure 1 (c)∗1∗2

RIKEN Nishina Center
Department of Physics, Toho University

Fig. 1. (a) Tapered glass capillary optics mounted at a beam
port of BL-W30. (b) Al2 O3 fluorescent plate with 5-mm
interval grid in BL-W15. (c) Round-shaped beam spot.
(d) A spot defocused horizontally but focused vertically.

Fig. 2. Pelletron terminal voltage monitor (blue) and microbeam intensity (green) as a function of time.

shows a round shaped beam spot. Because the position
ﬂuctuation was mainly in the horizontal direction, thebeam was defocused horizontally but focused verticallyas shown in Fig. 1 (d).
After proﬁle tuning, the beam was switched to BLW30. The upper curve in Fig. 2 shows the time evolutionof the Pelletron terminal voltage monitor (∼ 5.56 V) proportional to the terminal voltage setting to 1.400 MV.
The standard deviation (σ) was 2.372 kV (0.169%),
which corresponds to ∼ 5 mm ﬂuctuation at the capillary entrance. However, the modiﬁed shape as shownin Fig. 1 (d) realized the stable rate of the microbeam
around 1000 ions per second even when the terminal
voltage became more unstable within 0.9% peak-topeak. The ﬂuctuation σ of ion-count rate (microbeam
intensity) in Fig. 2 was 8.10%, which became successfully stable. Before this method, the ion-count rate had
ﬂuctuated between 0 and 1000 counts/s randomly.

- 225 -

IV. OPERATION RECORDS

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Program Advisory Committee meetings
for nuclear physics and for materials and life experiments
K. Yoneda,∗1 K. Ishida,∗1 H. Yamazaki,∗1 N. Imai,∗2 Y. X. Watanabe,∗3 K. Yako,∗2 H. Miyatake,∗3
M. Iwasaki,∗1 and H. Ueno ∗1
The Program Advisory Committees (PAC) are in
charge of reviewing the scientific proposals submitted
for the use of the accelerator facility of RIKEN Nishina
Center (RNC). Three PAC meetings were held in fiscal
year 2018; one for the proposals of nuclear physics (NPPAC), and two for the proposals of materials and life
experiments (ML-PAC). The NP-PAC reviewed experimental proposals at RIBF, whereas the ML-PAC reviewed proposals at Rutherford Appleton Laboratory(RAL) and RIBF.
NP-PACThe 19th NP-PAC meeting was held from November 29 through December 1, 2018,1) with attendance of
16 PAC members. 33 proposals including 3 construction proposals were reviewed, and 14 proposals wereapproved as grade A. The outcome of the NP-PAC
meeting is summarized in Table 1.
The 19th NP-PAC members are as follows:
A. Bracco (INFN, the chair), D. Ackermann (GANIL),
A. Andreyev (University of York), I. Hamamoto (University of Lund/RNC), R.V.F. Janssens (Universityof North Carolina at Chapel Hill), A.O. Macchiavelli(LBNL), D.J. Morrissey (MSU), T. Nagae (Kyoto University), H. Nakada (Chiba University), K. Ogata(RCNP, Osaka University), T. Rauscher (University of Hertfordshire), K. Sekiguchi (Tohoku UniverTable 1. Summary of the outcome of the 19th NP-PAC
meeting. The proposals ranked as A are treated as “approved” proposals.
19th NP-PAC (November 29–December 1, 2018)
requested
approved
proposals (days) proposals (days)
GARIS
2 (31.5)
1 (17)
CRIB (AVF)
5 (44.5)
3 (35)
RIPS
0 (0)
0 (0)
KISS
0 (0)
0 (0)
BigRIPS/ZD
10 (71)3 (13.5)
SHARAQ/OEDO
6 (53.5)
2 (16)
Rare RI Ring
1 (13.5)
1 (9)SAMURAI
9 (74.5)
4 (20)Total
33 (288.5)
14 (110.5)

∗1
∗2
∗3

RIKEN Nishina Center
Center for Nuclear Study, the University of Tokyo
Wako Nulcear Science Center, Institute of Particle and Nuclear Studies, KEK- 227 -sity), H. Simon (GSI), P. Van Duppen (KU Leuven),
Y.-H. Zhang (IMP).
ML-PACThe 16th and 17th ML-PACs were held on July 20,
2018, and in January , 2019, respectively.2) The PAC
meeting was held for the 16th ML-PAC, and the proposals were reviewed with only submitted documents,
as was done from in the 13th ML-PAC meeting. The
17th ML-PAC review was done only by mail review, as
the number of proposals to review was relatively small.
The outcome of the meeting is summarized in Table 2.
The 16th and 17th ML-PAC members are as follows:
A. Hiller (ISIS, RAL, the chair), T. Azuma (RIKEN),
R. Kadono (KEK), A. Kawamoto (Hokkaido University), S. Kawano (University of Tokyo), K. Kubo
(ICU), P. Mendels (University of Paris), Z. Qin (Chinese Academy of Sciences), H. Yamase (NIMS), andX.G. Zheng (Saga University).

Table 2. Summary of the outcome of the 16th and 17th
ML-PAC meetings. The RIBF proposals ranked as A
are treated as “approved” proposals.
16th ML-PAC (July 20, 2018)
requested
approved
proposals (days) proposals (days)RAL
14 (68)9 (25)
RIBF
2 (8)
2 (8)
Total
16 (76)
11 (33)17th ML-PAC (January 2019)
requested
approved
proposals (days) proposals (days)
RAL
7 (39)
6 (19)
RIBF
1 (1)
1 (1)
Total
8 (40)
7 (20)

References

1) http://www.nishina.riken.jp/RIBF/NP-PAC/index.html .
2) http://www.nishina.riken.jp/RIBF/ML-PAC/index.html .

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Beam-time statistics of RIBF experiments
K. Yoneda ∗1 and H. Ueno ∗1
This report describes the statistics of the beam times(BTs) at the RIBF facility in fiscal year (FY) 2018.
The BTs are categorized into the following two groups:
high-energy-mode and low-energy-mode BTs. In theformer mode, the beams are delivered in the acceleration scheme of AVF, RILAC, or RILAC2 → RRC→ (fRC → IRC →) SRC, where the accelerators inparentheses can be skipped in cascade acceleration depending on the beam species used. In the latter mode,
the acceleration scheme is AVF or RILAC (→ RRC).
The BTs in the high-energy mode were scheduledfrom May to June and from October to December 2018,considering the restriction of utility-power use, budgetary constraints, the maintenance schedule of the accelerator system and co-generation system, etc. In theseries of experiments performed in spring, the primarybeam of 18 O was provided to users, and the 238 U primary beam was provided in autumn. Ten experiments
approved by the RIBF Program Advisory Committees(PAC)1) with an approved BT of 59 days were conducted. The facility development programs used 3.5
days of BT; these are defined as machine study (MS)experiments. Two PAC-approved experiments had tobe canceled due to sudden schedule change caused byaccelerator troubles.
The summary of the high-energy-mode BTs in
FY2018 is given in Fig. 1 as a bar chart. User time decreased compared to the BT in FY2017; this is mainly
due to the startup tuning of the newly-introduced
RRC-RF cavities, and troubles of water leakage fromthe new RF cavities. The total length of the MS isalmost as short as the length in FY2017. Even though
there remain only few newly-introduced facility device requiring beam tests, the opportunities of machinestudies should be promoted as an investment for expanding the potential capability and availability of the
facility.
The summary of the low-energy mode is shown in
Fig. 2. Here, the BTs are classified based on the accelerator operation modes, i.e., AVF standalone, RILAC
standalone, and RRC. In FY2018, the total BT lengthof the low-energy mode increased compare to that in
FY2017 regardless of the RILAC shutdown started in
the middle of June 2017 for accelerator upgrade. The
relatively longer AVF-standalone time and RRC time
are due to the long runs for the transmutation experiment and superheavy element search. It is anticipatedthat RRC will be mostly used for the superheavy element search experiments until RILAC becomes available again in FY2019.

∗1

RIKEN Nishina Center- 228 -

Fig. 1. Bar chart showing the BT statistics for high-energymode experiments from FY2007 to FY2018. The accelerator tuning time and Nishina Center mission time are
not included.

Fig. 2. Bar chart showing the BT statistics for low-energymode experiments from FY2007 to FY2018.

Reference

1) K. Yoneda, K. Ishida, H. Yamazaki, N. Imai, Y. Watanabe, K. Yako, H. Miyatake, H. Ueno, in this report.

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Electric power consumption of RIKEN Nishina Center in 2018
E. Ikezawa,∗1 Y. Watanabe,∗1 H. Yamasawa,∗1 and O. Kamigaito∗1
The average hourly electrical power consumption foreach day in the RIKEN Nishina Center (RNC) in 2018is shown in Fig. 1. The total electrical power consumption by RNC in 2018 was 54,200 MWh, which
was 26% lower than that in 2017. When RI Beam
Factory (RIBF) experiments using an uranium (238 U)
beam were conducted, the maximum electrical power
supply to the RIKEN Wako campus from the commercial power reached 19.2 MW with a CGS output of
5.0 MW on November 15, 2018, and the maximum electrical power consumption of RNC reached 15.4 MW on
November 12, 2018.

Fig. 1.

∗1

Average hourly electrical power consumption for each day in RNC in 2018.

RIKEN Nishina Center- 229 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Operation report of the ring cyclotrons in the RIBF accelerator
complexJ. Shibata,∗1 K. Suda,∗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 K. Ozeki,∗2 N. Sakamoto,∗2 N. Tsukiori,∗1 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. 2018 is presented. Table 1 presents a summary of the beams accelerated by these cyclotrons. The availability is defined as
the ratio of the actual beam service time to the scheduled beam service time, which is an index of the stable
operation of accelerators. Multiple experiments supplying identical beams are shown as a block, whereas theexperiments with the 51 V beam are not shown, because
the new element search experiments are conducted as
the closed beam time under the Nishina Center Director. The total beam supply time was 1719.4 h excluding the V beam supply. The service of RRC was notavailable due to the upgrade of the resonators1) during the period of two months from February. In theold facility (RARF), the actual beam service time was
477.0 h, and the availability was 108.5%. Stable beams
were supplied as usual. In the new facility (RIBF), twobeam services were carried out. The total beam supply
time was 1242.4 h, and the availability was 84.2%.
For the synthesis of the 119th element, three beamservices were carried out. The 51 V beams were suppliedwith the availability of 73.5%. The availability was low
due to the vacuum leakages caused by cooling waterleakage at the new resonators of RRC and had to beaborted for repairs.

For the beam supply of 18 O, the maximum beam intensity was 600 particle nA, and the availability was
100.6% for seven experiments. There were failures in
the RRC, namely in the plate and filament power supplies for an intermediate amplifier of RF No. 1 and ina vacuum control system, which seemed to be caused
mainly by radiation.
A 238 U beam at 345 MeV/nucleon was supplied foreight experiments, and the maximum beam intensityof 72 particle nA was the highest ever. The availability decreased to 67.8% owing to several troubles.
The beam supply was started 7.5 d later than scheduled due to the failures and repairs of the SRC-EIC
and -EDC, abnormal termination of the rotating charge
stripper, and a severe beam tuning to reduce beamlosses. The rotation-stops of the charge stripper occurred frequently even during the beam supply. Finally,a ferrofluidic seal was exchanged to recover stable operation. Furthermore, a vacuum leakage happened again
at the RRC resonator No. 1 in November, and the repair was performed. It took 8 d for the repair and beamtuning to resume the beam supply.
Reference

1) K. Yamada et al., “Remodeling of acceleration cavity resonators for RIKEN Ring Cyclotron”, in this report.

Table 1. Summary of the accelerated beams in 2018.

∗1∗2

SHI Accelerator Service Ltd.
RIKEN Nishina Center- 230 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

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 H. Yamauchi,∗2 K. Oyamada,∗2 M. Tamura,∗2 A. Yusa,∗2 K. Kaneko,∗2 and O. Kamigaito∗1
For the upgrade of RILAC, the following works havebeen in progress at the LINAC building during thereporting period. The details are described elsewherein this progress report.
(1) The new 28 GHz superconducting electron cyclotron resonance ion source and the low energy beam transport (LEBT) were installed.
The necessary preparation for the test was conducted.
(2) The section after the A2 cavity reconstituted.
The necessary preparation for the installation ofa superconducting RILAC (sRILAC), middle energy beam transport (MEBT), high energy beamtransport (HEBT), and helium refrigerator was
conducted.
(3) The GARIS3 was installed in the e2 beamcourses in target room no. 1.
(4) The air cooling fan coil units in the radiationcontrolled area were replaced.
We performed the following maintenances during thereporting 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.

∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

- 231 -

(2) The water pumps were subjected to simple inspection. All cooling towers were subjected tomonthly inspection.
(3) All turbomolecular pumps were subjected tosimple inspection. Cryogenic pumps used for the
No. 5 cavity, A1 cavity, and standby units were
overhauled.
We performed the following repairs during the reporting period. The details are described elsewhere inthis progress report.
(1) The No. 5 cavity had a serious vacuum leakdue to a deteriorated vacuum gasket of the center conductor in the cavity. The external dimensions of the gasket are 10 ± 0.1 mm height,
8 ± 0.1 mm width, and 4273 ± 13.5 mm length in
the radial direction. We replaced it with a newone. In addition, silver plates for the electricalcontact of the center conductor were replacedwith new ones.
(2) The bottom plate of the A1 cavity had a vacuum leak. We repaired the plate with a repair
material.

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Operation report on the RIKEN AVF cyclotron for 2018
K. Kobayashi,∗1 K. Ozeki,∗2 M. Fujimaki,∗2 N. Fukunishi,∗2 S. Fukuzawa,∗1 A. Goto,∗2 M. Hamanaka,∗1
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 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. Oyamada,∗1 N. Sakamoto,∗2 J. Shibata,∗1 K. Suda,∗2 M. Tamura,∗1 N. Tsukiori,∗1
A. Uchiyama,∗2 S. Watanabe,∗2 T. Watanabe,∗2 Y. Watanabe,∗2 K. Yadomi,∗1 K. Yamada,∗2 and A. Yusa∗1
The yearly report on the operation of the RIKEN
AVF cyclotron (denoted as AVF hereafter) for the period January–December 2018, is presented. AVF hasfour beam courses of various ion beams used for standalone operations: C01 (machine study), C03 (RI production), E7A (CRIB), and E7B (student experiment).
In addition, AVF is used as an injector of RRC. In
this mode, beams are delivered to three courses: RRCRARF, RRC-IRC E5, and RRC-IRC-SRC. The beamcourses are shown schematically in Fig. 1.
The yearly operation statistics and beams acceleratedusing AVF are summarized in Table 1 and 2, respectively. Remarkable operations achieved this year include a development test of C-foil and a demonstration
experiment of nuclear transmutation. For C-foil development, an endurance test was performed for 150 h at
C03. The experiment to demonstrate nuclear transmutation was carried out at C03. Most of the delivered
time to C03 (2067 h, twice as long as that in the usualyear) was spent on this experiment. In the RIBF experiment (RRC-IRC-SRC course), the beam was continuously delivered without any break for 600 h, out of a
total delivered time of 820 h. In a total operation timeof 5042 h, only 7 h was spent for AVF repairs. In thelast experiment in July, a cooling water pipe of PHASESLIT leaked inside the AVF vacuum. Therefore, theRARF experiment was canceled.
Table 1. Comparison of AVF operation statistics with thatof the previous year.

Table 2. AVF beam list in 2018.

Fig. 1. Overview of AVF cyclotron with ion sources, experimental courses, and beam transport line to RRC.
∗1
∗2
∗3

SHI Accelerator Service Ltd.
RIKEN Nishina Center
Center for Nuclear Study, the University of Tokyo- 232 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Present status of the liquid-helium supply and recovery system
T. Dantsuka,∗1 H. Okuno,∗1 M. Nakamura,∗1 M. Kase,∗1 S. Tsuruma,∗1 M. Ohshima,∗2 H. Miura,∗2
H. Shiraki,∗2 H. Hirai,∗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 failure due to deterioration over time has increased
in recent years, duplication of liqueﬁer was conducted
in 2017. The new liqueﬁer can produce liquid helium
at a liquefaction rate of 220 L/h from pure helium gas.
Consequently, even when the liqueﬁer breaks down, it
can be repaired without stopping the supply of liquid
helium.
The volumes of liquid helium supplied each year
from 2001 to 2017 are shown in Fig. 1. From 2001
to 2013, there was a gradual increase in the supplied
volume, with two declines in 2009 and 2011. In 2014,
the supplied volume decreased owing to a malfunctionin the system. However, in 2015, the supplied volume
returned to its original value. In 2016, the supplied
volume decreased but slightly increased in 2017.

Other laboratories
Quantum Funconal System Research GroupRadioacve Isotope Physics Laboratory
Surface and Interface Science Laboratory

The purity of helium gas recovered from the laboratories gradually improved after the new system wasconstructed. At present, the impurity concentration in
the recovered gas rarely exceeds 200 ppm. The volumeof helium gas recovered from each building in the Wako
campus as well as the volume transported to the liquid helium supply and recovery system were measured.
The recovery eﬃciency, which is deﬁned as the ratio of
the amount of recovered helium gas to the amount of
supplied liquid helium, was calculated. The recovery
eﬃciency for the buildings on the south side of the
Wako campus, namely the Cooperation Center building of the Advanced Device Laboratory, Chemistry andMaterial Physics building, and Nanoscience Joint Laboratory building, increased to more than 85%.
Reference
1) K. Ikegami et al., RIKEN Accel. Prog. Rep. 34, 349(2001).

Emergent Phenomena Measurement Research Team
Exploratory Materials Team
Surface Chemistry Laboratory
Molecular Characterizaon Team

180000160000Liquid Helium (L)140000120000100000
80000
60000
40000
20000
0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
Fiscal Year
Fig. 1.

∗1∗2

Volumes of liquid helium supplied to the various laboratories for each fiscal year from 2001 to 2017.

RIKEN Nishina Center
Nippon Air Conditioning Service K.K- 233 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Present status 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 R. Sasaki,∗2 K. Kimura,∗2 M. Noguchi,∗3 and N. Suzuki∗3
After the September 2017 incident wherein water pipelines for the refrigerator system were severely
blocked by muddy impurities, we replaced the entire piping of the cooling water system for the BigRIPS cryogenic plant in March 2018. Figure 1 shows the new cooling water pipelines for the compressor unit and refrigerator. We changed the cooling water system for the refrigerator from the cool-water system using cooling towers to the chilled-water system using RIBF absorption
chillers. The cooling eﬃciency of the turbine system has
greatly improved.
Based on the RIBF beam-time schedule, we performed
two continuous operations at the BigRIPS cryogenic
plant in 2018. The ﬁrst operation lasted from Apr. 17
to June 18 and the second from Sept. 28 to Dec. 17. We
operated the cryogenic system without any trouble inboth periods. We measured the vibrations of the compressor unit and observed the low oil contamination inhelium gas during operations. The total operation timeof the compressor unit was 68,291 h.
Figure 2 shows the vibration acceleration in the vertical and horizontal directions as a function of the total operation time. We measured the vibrations of thecompressor at the high-pressure and low-pressure sides
since 2015. Except the rapid increase of the vibration
acceleration at the operation time of 59,000 h, which indicates the damage in the baring unit that occurred in
Dec. 2016,1) the vibration acceleration stayed less than
8 m/s2 during the operation period.
Figure 3 shows an estimate of the oil contaminationlevel at the entrance of the third coalescer vessel as afunction of the coalescer ﬁlter operation time. By mea-

Fig. 1. New cooling water piping for the compressor and refrigerator.
∗1
∗2
∗3

RIKEN Nishina Center
Nippon Kucho Service Co., Ltd.
Mayekawa Mfg. Co., Ltd.

Fig. 2. Vibration acceleration of the compressor unit.

Fig. 3. Oil contamination at the entrance of the third coalescer vessel.

suring the operation interval of the drain valves of the
coalescer vessels in the compressor unit, the oil contamination level was evaluated.2) The navy blue, green,and yellow diamonds represent the estimates for the
2008–2009, 2010–2011, and 2012–2013 operations, respectively. The estimate for the 2014–2015 and 2016–2018 operations are shown with pink and red diamonds,
respectively. The oil contamination values measured using the oil check kit are also shown. The open triangles, squares, and circles represent the results for the
2008–2009, 2010–2011, and 2012–2013 operations. The
results for the 2014–2015 and 2016–2018 operations areindicated by the open diamonds and circles, respectively.
Both estimations of the oil contamination level are consistent with each other and the performance eﬃciencyof the latest ﬁlter elements seems to be better than thatof the others.
References

1) K. Kusaka et al., RIKEN Accel. Prog. Rep. 50, 285 (2017).
2) K. Kusaka et al., RIKEN Accel. Prog. Rep. 41, 309 (2010).

- 234 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

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
In this paper, the results of radiation monitoringat RIBF, conducted at the border of the facility andthe radiation-controlled area are reported. In addition, the residual doses along the accelerator setups
are presented. In 2018, a 238 U beam of approximately
345 MeV/nucleon was provided at an intensity of 70
particle nA during October to December. A 18 O beamof approximately 230 MeV/nucleon of 700 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: the roofs of theRRC, IRC, and BigRIPS. Figure 1 shows the annual
neutron dose at these positions. In 2018, even the highest annual dose of 51 µSv/y at the IRC roof was lower
than the 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 2018 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 thecyclotrons was measured just before the maintenancework. The residual dose depends on factors such as

1000

µSv/y

100

10

1
2000

2005

2010

2015

year

Fig. 1. Radiation dose at the boundary of radiationcontrolled area.
∗1

∗2
∗3

RIKEN Nishina Center
Japan Environment Research Corporation
Daiwa Atomic Engineering Corporation- 235 -

Fig. 2. Dose rates of residual radioactivity at the deflectorsof five cyclotrons.

beam intensity, accelerator operation time, and coolingtime. The dose rates from 1986 are shown in Fig. 2.
The dose rates for FRC, IRC, and SRC are shown foryears after 2006, when the RIBF started its operation.
For AVF, the dose rate increased in 2006 because theradioisotope production was started in that year andthus, the beam intensity increased.
The residual radioactivity along the beam lines wasmeasured after every experiment. Figure 3 shows thelocations of measurement points where high residual
doses were observed. Table 1 lists the dose rates,
beam conditions, and cooling time at the measurement
points. The maximum dose was 17.8 mSv/h at point
19, which is in the vicinity of beam dump of BigRIPS.
The radioactivity in the closed cooling system at BigRIPS was measured. The water for the F0 target,
exit beam dump, and side-wall dump were sampled inJune. The water in the closed cooling systems for theF0 target and exit beam dump was replaced in May
2018. Therefore, the detected radioisotopes in the F0target and exit beam dump were generated during one
month of operation in RIBF. For the side-wall beamdump, part of the water was replaced in January 2018,
but all the water was replaced in March 2015; the results are presented in Table 2. A liquid scintillation
counter (LSC-7400, Hitachi Co. Ltd.) was used forthe low energy β ray of 18 keV from H-3 nuclide. A
Ge detector (GC2019, Canbbera Co. Ltd.) was also
used for the γ rays emitted from other radionuclides.
The radionuclides, except H-3, were already filteredby an ion exchange resin in the closed cooling systems.

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Although the overall value of contamination was lessthan the legal limit for drain water, as presented 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 case of awater leakage.
The e-learning module, which can be accessed anytime from anywhere (even from outside RIKEN), hasbeen used to the re-train the radiation workers at
RIBF. Approximately 630 radiation workers have completed the training in 2018.

Table 1. Dose rates measured at beam lines in 2017.
Points 1–24 indicate the locations where measurements
were taken as shown in Fig. 3.

Point

Dose Date
Energy Intensity Coolingrate (M/D) Particle (MeV/u)(pnA) time
(μSv/h)
(h)

1
2

200
400

8/24
8/24

Ar-40
Ar-40

5.2
5.2

40
40

573
573

3

170

8/24

Ar-40

5.2

40

573

4

1000

10/10

N-14

135

357

120

5

250

8/24

Ar-40

95

1

571

6

150

8/24

Ar-40

95

1

571

7

5500

12/17

U-238

50

342

159

8

1800

12/17

U-238

50

342

159

9

700

12/17

U-238

50

342

159

10

100

12/20

U-238

345

72

231

11

9600

12/20

U-238

345

72

231

12

140

12/20

U-238

345

72

231

13

350

12/20

U-238

345

72

231

14

1600

7/25

Ar-40

160

1

983

15

400

7/25

Ar-40

160

1

983
1133

16

200

7/25

O-18

230

600

17

1430

12/20

U-238

345

72

231

18

3450

12/20

U-238

345

72

231

19

17800

12/20

U-238

345

72

231

20

241

12/20

U-238

345

72

589

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.

Fig. 3. Layout of the beam lines at RIBF. The measurement locations listed in Table 1 are indicated.

- 236 -

Cooling Nuclide Concentration[a] Limit[b] Ratio towater(Bq/cm3) limit [a/b](Bq/cm3)
3.4
60
5.8e-2BigRIPS H-3
F0 targetsummation 5.8e-2
BigRIPS H-3
3.8
60
6.4e-2exit
Mn-54
1.3e-31)1
1.3e-3beamsummation 6.4e-2
dump
53.
60
0.89
BigRIPS H-3
8.6e-230
2.9e-3side-wall Be-7
Mn-54
1.2e-31
1.2e-3beam
dump
summation 0.89
1) read as 1.3× 10-3

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)

Operation of the Pelletron tandem accelerator
T. Ikeda,∗1 M. Hamagaki,∗1 and H. Sato∗1
The tandem accelerator (Pelletron 5SDH-2, 1.7 MVmax.) in the Nishina R&D Building, which is managed
by the Detector Team of RNC, is a joint-use equipment
at the Wako campus. Figure 1 shows the configurationof the beam elements. Two ion sources are located in
the upstream of the accelerator. One is the RF chargeexchange ion source called Alphatross, which is mainly
used for the extraction of He− ions. The negative charge
state of He ions is realized by transmission through Rb
vapor. The other one is the Source of Negative Ions by
Cesium Sputtering (SNICS). Almost all other ions canbe extracted from SNICS as negative ions, e.g., H− andC− . These ions are installed as a solid cathode, e.g.,
TiH2 for H− , to be sputtered by Cs ions.1) Thus far, theion species of H, He, Li, B, C, N, O, Si, Ti, Ni, Cu, andAu have been accelerated by 0.5–1.7 MV.
The accelerator has four beam lines named BL-E/Wnn(nn stands for the bending angle). BL-E45 is used forsurface modification. BL-E15 is reserved for the analysis of Rutherford backscattering (RBS) spectrometry/elastic recoil detection analysis (ERDA). The microbeam
port is BL-W30, which employs tapered glass capillary

Fig. 1. Pelletron tandem accelerator and beamlines in the
Nishina R&D Building.

Table 1. Beam conditions and experiments conducted in thetandem accelerator.
Ion

Energy[MeV]

Beam current[pnA]

ExperimentOperation
time [days]

1H+

1.0–3.0

0.008–420

Irradiation

25

4He+, 2+

2.0–4.8

0.2–300

Irradiation

4

with an end-window to irradiate biological sample in solution.
The range of the ion beams is several 10 µm at mostfor water (density = 1 g/cm3 ). Only H+ can have ranges
greater than 100 µm for water. All the experiments except for microbeam irradiation with the glass capillaries
should be performed in vacuum chambers, where heavy
ions of several MeV, such as Au ions, can provide stopping powers greater than 200 keV/µm at only the surface
layer of samples or detector-sensitive areas.
This year, BL-W15 (Fig. 2) started to be used again
after the renewal of the beam diagnostic system consisting of two Al2 O3 fluorescent plates with current monitors. This system helps to focus the beams down to afew cm in diameter at the end of the line by tuning aquadrupole magnet as shown in Fig. 1. The beam line
was used for the experiments of detector calibration andNishina School.
During the annual reporting period from Jan. 1 to Dec.
31, 2018, the total machine time including a machine
study was 29 days, where the condition test of the ion
sources is not counted. The ion species accelerated in2018 were only light ions H+ , He+ , He2+ with energies
ranging from 1.0 to 4.8 MeV, as summarized in Table 1.
Experimental studies were performed on the following
subjects.
(1) Machine study of a proton microbeam using tapered glass capillaries (1 day)(2) Test of microbeam irradiation on single cells at
BL-W30 (24 days)(3) ERDA experiments using carbon ions (0 day)(4) Educational experiment of proton capture by acarbon nucleus for Nishina School (1 day)(5) Development of charged particle/gamma ray detector to be used for RIBF experiments (2 days)(6) Other development using protons (1 day)Fig. 2. BL-W15 started to be used again as a multipurpose
beam line after the renewal of the beam diagnostic system.
The degree of vacuum level for the user setup is required
to be better than 10−4 Pa. (Left). A setup for calibrationof gamma ray detectors using a resonance reaction witha carbon target bombarded by 1 or 2 MeV proton beams(Right).
∗1

RIKEN Nishina Center

Since the experimental area is approved as a secondclass radiation-controlled area, the users of all measurements can access their setup even during the beam irradiation time. The users are free from any setup for
remote control utilities. These points are the advantagesof using the RIKEN Pelletron accelerator.
Reference

1) R. Middleton, A Negative-Ion Cookbook (Univ. Pennsylvania, Philadelphia, PA 19104, 1990).

- 237 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 52 (2019)Fee-based activities by the industrial application research teamA. Yoshida,∗1 T. Kambara,∗1 H. Haba,∗1 and D. Mori∗1
Fee-based activities conducted by the Industrial Application Research Team (former Industrial Cooperation Team) in 2018, which include the utilization ofheavy-ion beams in the industry and distribution ofradioisotopes, 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) In 2018,
four fee-based beamtimes were successfully performed
for the irradiation test of space-use semiconductor devices: an 80-hour beamtime with a 70-MeV/nucleon
84
Kr beam in February, 40-hour beamtime with a 70MeV/nucleon 84 Kr and 20-hour beamtime with a 95MeV/nucleon 40 Ar in July, and 8-hour beamtime witha 70-MeV/nucleon 84 Kr beam in December. The former three beamtimes were at the E5A and the last
one was at the E3A beamline, where the clients irradiated their samples in the atmosphere. In addition,
we performed a three-hour machine-study beamtime
in February with a 10.75-MeV/nucleon 136 Xe beam,in which we studied the properties of beam to prepare
future fee-based utilizations.
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), and 85 Sr(T1/2 = 65 days), produced by the Nuclear Chemistry
Research Team (former RI Applications Team) at the
AVF cyclotron. According to a material transfer agreement (MTA) drawn between JRIA and RIKEN, JRIA
mediates the transaction of RIs and distributes themto users. 65 Zn and 109 Cd are delivered approximately
two weeks after the acceptance of an order. 85 Sr and
88
Y, which have shorter half-lives, are not stocked like65
Zn and 109 Cd but are produced in a scheduled beamtime after an order is accepted. Therefore, they are delivered two months or more after the order is placed.
These details can be found on the online ordering system J-RAM3) of JRIA.
In 2018, we delivered three shipments of 65 Zn witha total activity of 9.7 MBq, two shipments of 88 Y witha total activity of 2 MBq, and no shipments of 109 Cd,
The final recipients of RIs were a university, a research
institute, and a medical research center.
Figure 1 shows the yearly trends in the number oforders and the amount of distributed RIs. Comparedwith 2017, the amount of distributed 65 Zn increased
by a factor of 2.6 and that of 88 Y remained the same.
We anticipate that the demand for short-lifetime RIs
would increase in future and are considering to add∗1

RIKEN Nishina Center- 238 -

Fig. 1. Number of orders (upper) and amount (lower) of
the RIs distributed yearly from 2007 to 2017. The distribution of 88 Y started in 2010 and that of 85 Sr in
2015.

such RIs to the fee-based distribution. As the firststep, we announced the distribution of the new RI 67 Cu(T1/2 = 61.8 h) in August. It will be produced in ascheduled beamtime after an order is accepted.
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://www.j-ram.net/jram/DispatchTopPage.do(Japanese).

V. EVENTS

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 52 (2019)

DIS2018 International Workshop
Y. Goto∗1 for the DIS2018 Local Organizing Committee
DIS2018 International Workshop was held from
April 16th to 20th at Port Island, Kobe. It was the
26th in an annual series of International Workshops
on Deep Inelastic Scattering (DIS) and Related Subjects covering an eclectic mixture of material related toquantum chromodynamics (QCD) and DIS as well asa general survey of the hottest current topics in highenergy physics. The majority of the program was devoted to the most recent results from experiments at
BNL, CERN, Fermilab, Jeﬀerson Lab, and KEK. Relevant theoretical advances were also covered in detail.
On the ﬁrst day, topics of this year were overviewed
both theoretically and experimentally through plenary
talks. This year, experimental reviews were presented
for each topics of physics instead of each facility owing to the expansion of the community, which was
dominated by LHC. The Electron Ion Collider (EIC)
became more realistic and the nuclear physics community showed more interest in this future facility.
First, the nucleon structure with unpolarized, polarized, and neutrino scatterings in various energies werereviewed. Next, hadron ﬁnal states, hadron scatterings
with perturbative QCD and jet, precision measurements, and the search of physics beyond the standard
model (BSM) were reviewed and theoretical ideas were
presented. In the last session, soft scatterings, fragmentation and exotic hadrons, three-dimensional (3D)
hadron structure, and hadron structure with lattice
QCD were discussed as non-perturbative QCD physics
with emphasis on Japanese activities.
From the second to the fourth day, parallel sessions
were held for the following working groups (WGs):• WG1: structure functions and parton densities• WG2: low x and diﬀractive physics• WG3: Higgs and BSM physics in hadron collisions• WG4: hadronic and electroweak observables• WG5: physics with heavy ﬂavors• WG6: spin and 3D structure• WG7: future of DIS
A special topic for this year’s workshop was the discussion of the future projects of DIS regarding the submission of a document to the European Strategy Update for Particle Physics (ESUPP) led by the International Advisory Committee of the workshop. A special
joint session for all working groups was held after the
regular parallel sessions in the second day. Panelists
from EIC, LHeC (e + p collider at LHC), VHEep (e + p
collider with a plasma accelerator), and e + p option of
FCC (Future Circular Collider) presented their new accelerator facilities, theorists reviewed QCD and heavy∗1

RIKEN Nishina Center- 239 -

Fig. 1. Group photo of the DIS2018 workshop.

ion theories motivating these projects with broad perspective, and participants discussed the involvement ofthese projects in the document.
On the last day (ﬁfth day), summaries from each
WG were given by the coveners of the WG in the morning session. Two future projects, EIC and LHeC, andrelated physics topics were reviewed to discuss important points from their point of view in the afternoon.
The workshop was organized by the Graduate Schoolof Science, Kobe University, RIKEN Nishina Center,
and KEK with support from Grant-in-Aid ScientiﬁcResearch on Innovative Areas, MEXT, Japan: “Newexpansion of particle physics of post-Higgs era by LHC:
revealing the vacuum and space-time structure,” andsponsored by DESY, CERN, Kobe Tourism Bureau& Kobe Convention Bureau, and Tsutomu Nakauchi
Foundation for Promoting Conventions.
The workshop was held in two meeting locations:the Convention Hall of Kobe University for the plenary sessions and the Kobe International Convention Centre for the parallel sessions. A total of
254 participants demonstrated 256 presentations. A
group photo is shown in Fig. 1. Slides shown in theworkshop are available at https://indico.cern.ch/
event/656250/ and the proceedings of the workshop
are published online at https://pos.sissa.it/316.

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 52 (2019)

RIKEN Open Day 2018
K. Yoshida,∗1 and T. Uesaka∗1
RIKEN Open Day, where several laboratories showcased their experimental devices and research activity
to the public in RIKEN Wako campus, was held on
April 21, 2018. In the Nishina Center, 17 researchgroups, comprising 276 researchers participated in theevent, as listed in Table 1. The leaﬂet that introduced
the exhibition content in the Nishina Center is shownin Fig. 1. It was handed out to the visitors at RIBF.
The radiation controlled area in the RIBF building
was opened for visitors to display the superconducting
cyclotron SRC and other experimental devices alongwith the exhibition of laboratories. Dr. Wakasugi,
the group director of the Instrumentation Development
Group, gave a scientiﬁc lecture titled “What we can see
and do with the Storage Ring” at the Ohkochi Memorial Hall.
A total of 2533 and 7935 visitors came to RIBF and
RIKEN, respectively.

Table 1.

Fig. 1. Leaﬂet for RIKEN Open Day provided by Nishina
Center.

List of exhibitions.

Laboratory/Group/Team

Exhibition theme

Participants

Accelerator Group

The World’s Strongest Superconducting Ring Cyclotron

41

SLOWRI TeamIon Trap and Ultra-Slow RI Production

6

BigRIPS TeamSuperconducting RI Beam Separator BigRIPS

10

Rare RI-Ring Team

Precision Measurement of Nuclear Mass

10

Spin Isospin Laboratory.

Microscopes for Unstable Nuclei

22

SAMURAI TeamSAMURAI Magnetic Spectrometer

7

Nuclear Spectroscopy Laboratory

Tiny Magnets in Materials

12

Nishina Center

Nuclear Chart with LEGO Block

4

Nuclear Chemistry Research Team

Environmental Radiation and Useful Radiation

9

Ion Beam Breeding Team

Creating Amazing Plants

13Superheavy Element Research GroupThe Discovery of Nihonium

9

SCRIT Team

Handmade Spectrometer

9

Daruma Dolls Challenge

16Radioactive Isotope Physics Laboratory

See Radiation with Diffusion Cloud Chamber
Radiation Laboratory

Enjoy Spinning a Variety of Tops

13

Research Activities in the Experimental Hadron Physics
High-energy Astrophysics Laboratory.
Meson Science Laboratory
Quantum Hadron Physics Laboratory∗1

Dawn of Gravitational Wave Astronomy
Introductory Meson Science
Particle Physics Experience37
22

Elementary Particles, Nuclei and the Universe

9

Operation and Management

27

RIKEN Nishina Center- 240 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 52 (2019)

Workshop on “The r-process and unstable nuclei in multi-messenger
astronomy”
N. Nishimura,∗1,∗8 T. Abe,∗2,∗3,∗8 K. Nakazato,∗4,∗8 H. Sakurai,∗2,∗5 Y. Sekiguchi,∗6,∗1 H. Ueno,∗5 T. Uesaka,∗5
and K. Yoshida∗7,∗8
The workshop on “The r-process and unstable nuclei in multi-messenger astronomy”ʢ‫ڀݚ‬ձʮॏྗ೾‫؍‬ଌ࣌୅ͷ r ϓϩηεͱෆ҆ఆ֩ʯʣwas held on 20–22
June 2018 at the RIKEN Nishina center. This workshop was sponsored by the RIKEN Nishina Center and“Priority Issue 9 to be Tackled by Using Post-K Computer” (JICFuS), and was supported by the membersof RIBF Theory Forum.
The main scientific goal of the workshop was tosummarize the recent progress on the study of the rprocess, which is one of the most dominant nucleosynthesis processes for the cosmic origin of heavy elements
beyond iron. The workshop was directly motivatedby the recent (17 August 2017) successful observations of gravitational waves from a neutron-star merger
event (GW170817) and the associated optical transient
called kilonova/macronova, powered by r-process nucleosynthesis. We discussed several aspects of neutronstar mergers, focusing on nuclear physics, e.g., experiments/theory of unstable nuclei, gravitational wave astronomy, optical observation, and the theoretical models of neutron-star mergers using supercomputers suchas the K Computer.
The scientific program consisted of 8 sessions, i.e.,“multi-messenger astronomy of neutron-star-mergers,”“high-energy astronomy,” “the cosmic origin and evolution of r-process,” “the nuclear equation of state(EoS),” “nuclear masses,” “β-decay,” “nuclear fission,”and “the studies of unstable-nuclei in large facilities inJapan.” They covered a wide range of research fields inboth nuclear-physics and astrophysics, thus reflecting
the multi-disciplinary culture of nucleosynthesis studies. More than hundred participants gathered in the
RIBF lecture Hall (Fig. 1) to provide recent progressof their studies and to discuss the application to rprocess studies. This included 18 invited talks, 17 oral
contributions, 7 poster presentations.
The workshop started with a session for reportingthe “multi-messenger” observation of GW170817 including the kilonova, which opened a new era of astronomy triggered by gravitational wave detection anda theoretical understanding of the neutron-star merger
as the astrophysical site of the r-process. The re∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

Center for Gravitational Physics, YITP, Kyoto University
Department of Physics, The University of Tokyo
Center for Nuclear Study, The University of Tokyo
Faculty of Arts and Science, Kyushu University
RIKEN Nishina Center
Department of Physics, Toho University
Department of Physics, Kyoto University
RIBF Theory Forum

Fig. 1. Many interesting presentations were given at RIBF
Conference Hall in the 3-day workshop.

maining problems relevant to the nuclear-physics properties and aimed toward the complete understanding of kilonovae (and thus GW events) were highlighted. Following the talks on astronomy, the resultsof unstable-nuclei, e.g., the measurements of β-decay
half-lives at RIBF and the plan of experiments targeting the nuclear masses and neutron-capture in RIBF
were reported. Although there are still several gaps,
it appears that the r-process can connect (terrestrial)
nuclear-physics experiments with the transients in thesky.
GW170817 also imposes strict restrictions on the
EoS of neutron stars obtained from the GW signals
as well as traditional astronomical observation. Several talks focused on the physics of neutron stars andrelated astronomical phenomena with an emphasis on
the GW observation. The future experimental plansregarding the EoS were given as well as the theoreticalprogress of the EoS were presented.
The presentation files are available on the workshop website.1) The next iteration of this workshop2)
is planned to be held at Yukawa Institute for Theoretical Physics in Kyoto University in May 2019. We
will mostly focus on various topics in theoretical nuclear physics on such as the problems in r-process nucleosynthesis and (future) experiments of neutron-richnuclei far from stability.
References
1) URL: https://sites.google.com/view/rp2018/2) URL: https://www2.yukawa.kyoto-u.ac.jp/~rp2019/- 241 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 52 (2019)TESLA Technology Collaboration Meeting 2019
at RIKEN Nishina Center
N. Sakamoto ∗1
The mission of the TESLA Technology Collaboration1) (TTC) is to advance R&D on the SRF technology
and related accelerator studies across diverse scientificapplications, and to provide a bridge for the communication and sharing of ideas, developments, and testing across associated projects. The TTC meeting isheld once/twice a year changing locations in Europe,Asia, and North America. This time, the TTC meeting (Fig. 1) was held from 26 June to 29 June, 2018 at
RIKEN Nishina Center (RNC).2)
The TTC meeting covers subjects related to superconducting RF technology extensively. The timetable ofthis meeting is shown in Fig. 2. In each session, a specific subject chosen by the technical board members was
discussed intensively, and the information obtained fromexperimental and theoretical studies at various laboratories and companies was exchanged (see Table 1). In thismeeting, there were four working group sessions and one
hot topic session as follows:

Fig. 2. Timetable of the sessions for the TTC meeting at
RNC.
Table 1. Statistics of registrants of TTC2018 at RNC.

• WG1:What are the performance limits for low-beta
resonators?
• WG2:How to improve the present specification forbulk Niobium?
• WG3:High Q and high gradient performance.
• WG4:Special applications of SRF cavities.
• Hot Topic:Warm vacuum sections between low beta
cryomodules.
Note that since the meeting was hosted by RNC, subjects related to the low-beta ion accelerator were chosen for the WG1 and Hot Topic sessions. Eight plenary
talks were conducted on these subjects: Overview on
fabrication and treatment problems with Quarter- andHalf-Wave Resonator (QWR, HWR), Spoke (Z. Conway,
ANL), Overview talks for niobium material and specification (A. Palczewski, JLab), RIKEN overview and
SRF activities (O. Kamigaito, RNC), Lessons learned

Fig. 1. Group photo taken during the meeting.
∗1

RIKEN Nishina Center

Country
BrazilCanadaChina
FranceGermany
Italy
Japan

#
1
2
19
2
14
3
55

Korea
SwedenSwitzerland
UK
USA

4
4
4
1
34

Labs and Companies
CBMM
TRIUMF
IHEP, Peking U.,IMP, NINGXIACEA-Saclay,CEA-Gif-sur-Yvette
DESY, HIM, HZB
INFN-LNL,SAES
KEK, RNC, JAEA, QST,
MHI-MS, Tokyo Denkai, SAES,TOSHIBA, ULVAC
Miyoshi-Gokin, NEURON Japan,
R-DEC, ScandiNova, Sojitz
Korea U., IBS
ESS-ERIC, Uppsala U.
CERN
STFC Daresbury
Fermilab, JLab, SLAC,
FRIB/MSU, BNL, ANL,NW U.
Cornell U., OD U., Stony Brook
U., ATI, II-VI,ISOHIM

during module assembly and first cool-down test in
FRIB (T. Xu, MSU), Recent theoretical and experimental progress in N2 doping and infusion (M. Checchin,
Fermilab), Overview talks for Nb3Sn and other thinfilm technology (G. Eremeev, JLab), SC CH structurein Mainz/Frankfurt/Darmstadt (F. Dziuba, GSI), andTechnical progress of crab cavity in fabrication andtests at CERN (M. Garlasche, CERN). Two special
seminars were presented by H. Kawata from KEK and
K. Sakamoto from QST, introducing the industrial applications in compact-ERL at KEK and the high intensity
neutron source project at QST-Rokkasho.
The meeting was conducted successfully, and it had
more than 120 participants. The next meeting will beheld at TRIUMF (Vancouver, Canada) in February 2019.
References

1) https://tesla-new.desy.de .
2) https://indico.desy.de/indico/event/20010/program .
- 242 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 52 (2019)

Participation in Hokkaido Science Festival
N. Miyauchi ∗1
The year 2018 marked the 150th anniversary of thenaming of “Hokkaido.” As part of a series of events
commemorating the 150th anniversary, an event called“Hokkaido Science Festival” was hosted by the Hokkaido
government.1) The purpose of the event was to evoke
the challenging spirit of, in particular, young peoplein Hokkaido and to foster the youth into becoming
globally competitive human resources. The event washeld at the Hokkaido Prefectural Sports Center (alsocalled “Hokkai Kitayell”) on August 6–7, 2018 in Sapporo, and persons of considerable prominence attended
lectures that encouraged audience participation. Also,
companies, universities, and research institutes participated and conducted various explanation exhibitions
and experience-based programs. Figure 1 shows a venue
in the Hokkaido Prefectural Sports Center.
The Nishina Center (more precisely, User Liaison
Group) participated in the event, together with the
Public Relations Oﬃce, and conducted a workshop forchildren and an exhibition. The Public Relations Oﬃce
conducted an exhibition on “Kagakudo 100 books.2) ”
We introduced the RIBF facility through the following three exhibitions. The ﬁrst one was a participatory exhibition (i.e., workshop) entitled “Let’s make anihonium nucleus with ironing beads.” In this workshop, using ironing beads, which are children’s toys, theparticipants constructed a three-dimensional nihonium
pixel craft, after being explained about nuclear structures and how nihonium was discovered at the Nishina
Center. The scene of the workshop is shown in Fig. 2.
The second one was a panel exhibition. Here, in addition to panels on the research at the RIBF facility,
an oversized panel on SRC was also displayed. This
extra-large SRC panel was aimed at getting the people
to realize its scale while staying in Sapporo. Thus, by
taking pictures in front of it, the visitors were able totake pictures as if they had actually come to the RIBF
facility. This panel was particularly well-received bychildren and their parents.
The third one is the 3D nuclear chart made of Lego
Blocks (Fig. 3). This 3D nuclear chart drew considerable attention, probably due to the familiarity of Lego
Blocks and the rarity of the nuclear chart created with
it. The 3D nuclear chart was a good exhibit, because
it could generate interest owing to its interesting structure, and also because it allows researchers to makeintuitive explanations using the actual nuclear chart.
This display was also well received by the visitors.
Unfortunately, the location of our exhibition inside
the venue was not good, and hence the exhibit that
attracted the most participants was not ours. However,the visitors were able to thoroughly discuss the contentsof the exhibition and enjoyed the display.

Fig. 2. A photograph taken at the workshop for making anihonium nucleus with ironing beads.

Fig. 3. A photograph taken at the exhibition of a 3D nuclear
chart made of Lego Blocks.

Fig. 1. A photograph taken at an exhibition hall in the
Hokkaido Prefectural Sports Center∗1

RIKEN Nishina Center

References

1) http://www.pref.hokkaido.lg.jp/ss/tsk/hokkaido
sciencefestival.htm .
2) https://kagakudo100.jp/ .

- 243 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 52 (2019)

QNP2018 International Conference
Y. Goto∗1 for the QNP2018 Local Organizing Committee
QNP2018 International Conference was held from
November 13th to 17th in Tsukuba. It was the 8th
one in a series of International Conference on Quarks
and Nuclear Physics. The conference was held at the
Tsukuba International Congress Center (EPOCHALTSUKUBA). Experimentalists and theorists discussed
recent developments in the ﬁeld of hadron and nuclear
physics.
The conference began with plenary talks on neutron stars and hadron physics. Recent progress ingravitational waves and dense baryonic matter, andthe strangeness in neutron stars were discussed. In
the plenary sessions, experimental reviews on quarkand gluon structure of hadrons, hadron spectroscopy,
hadron interactions and nuclear structure, and hot anddense matter were presented. Theoretical reviews were
given for these subjects including reviews from lattice
QCD. There were also planary talks on experimental
facilities, GSI-FAIR project, Jeﬀerson Lab 12 GeV program, Belle-II project, J-PARC hadron project, andEIC project.
In four parallel sessions, following topics were covered:
Quark and gluon structure of hadrons
parton distribution functions, generalized parton distributions, transverse momentum distributions, and high-energy hadron reactions, among
others.
Hadron spectroscopy
heavy quark physics, exotics, and N ∗ , among others.
Hadron interactions and nuclear structure
hypernuclear physics, kaonic nuclei, and baryon
interactions, among others.
Hot and cold dense matter
quark-gluon plasma, color glass condensate, densestars, strong magnetic ﬁeld, mesons in nuclear
medium, and hadronization, among others.
One of the highlights of the conference was theresults from J-PARC on their ﬁrst major projecton strange nuclear physics. They obtained a large
charge symmetry breaking eﬀect in the hypernulei, theﬁrst clear Ξ hypernucleus, and Kaonic nucleus. JPARC physics covers wide areas of hadron physics,
strangeness nuclear physics, exotic hadrons, hadrons
in nuclear medium, nucleon structure functions, andquark-hadron matter.
Social events such as excursions to Tsukuba space∗1

RIKEN Nishina Center- 244 -

Fig. 1. Group photo of the QNP2018 conference.

center of JAXA and Belle-II of KEK, local sakebrewery and Mt. Tsukuba, soba noodle cooking, andKashima-Jingu shrine and historical Edo-taste downtown of Sawara were conducted, which were interactive. Participants also enjoyed good reception at thecongress center and conference dinner at the hotel
Grand Shinonome.
This conference was held with ﬁnancial supports by
KEK/J-PARC, RCNP, APCTP, JSPS Grant on Innovative Area: “Clustering as a window on the hierarchical structure of quantum systems,” Tsukuba Tourism
and Convention Association, and Tsukuba City. We
also received support from JAEA, RIKEN, and SOKENDAI.
A total of 216 participants from 25 countries attended the conference. There were 23 plenary talks
and 128 parallel talks (including 15 invited keynote
talks) in four parallel sessions. A group photo is shownin Fig. 1.
The full program and presentation ﬁles are available online at the conference website: https://
conference-indico.kek.jp/indico/event/33/ andthe proceedings of the conference will be published online in JPS Conference Proceedings.
A satellite workshop on “hadron structure and interaction in ﬁnite density matter” was held from
November 11th to 12th at KEK Tokai Campus
hosted by KEK and JAEA (http://j-parc-th.
kek.jp/workshops/2018/11-11/). Another workshop on the “progress on hadron structure functions in 2018” was held from November 18 to 19 at
KEK Tsukuba Campus (http://j-parc-th.kek.jp/
workshops/2018/11-18/).

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 52 (2019)

RIBF “Hodan-kai” meeting on the future of exotic nuclear physics
T. Matsumoto∗1,∗2 on behalf of the RIBF “Hodan-kai” meeting organizers
The second in the series of the RIBF “Hodan-kai”
meeting by young researchers was held at Kobe campus of RIKEN, Integrated Innovation Building, fromFeb. 18 to 20, 2019. The venue was in a relatively isolated place, and actually this was one of the key factors
for the success of the meeting; the participants wereforced to be in the meeting room and concentrate on
physics. The RIBF “Hodan-Kai” meeting is organizedby members of RIBF Theory Forum and supported by
RIKEN Nishina Center, RIKEN iTHEMS, and JICFuS. This meeting is aimed at an intensive discussion
based purely on curiosity, such as what is interesting
and what we want to do in the future in a frank andlow-pressure atmosphere. The style of “Hodan-kai” isthus diﬀerent from a usual workshop.
The ﬁrst “Hodan-kai” meeting was held at the sameplace from Jul. 21 to Aug. 2, 2017. In the ﬁrst meeting, we focused on the latest theoretical research of nuclear physics. The number of presentations was 23, and
we engaged in a heated debate. Although we sharedrecognition for the progress in theoretical research, we
wanted more discussions with experimentalists and researchers in various ﬁelds in order to deﬁnitize a new
agenda for the future of nuclear physics. The programand summary of the ﬁrst “Hodan-kai” meeting can beseen in the web site.1)
Based on the direction obtained at the ﬁrst meeting,
we arranged the second meeting as follows: 7 presentations on experimental research in nuclear physics,
6 presentations on theoretical research in nuclear

Fig. 2. Atmosphere of the banquet.

physics, and 12 presentations on some related ﬁelds,
namely deep learning, quantum computing, computational physics, weak measurement, super-heavy elements, hadron physics, and laser physics. The number of presentations was 14 for invited and 11 for contributed. In the second meeting, there were 42 participants from various ﬁelds, and we had a heated discussion beyond the scheduled time. Thus, it was avery meaningful meeting. The program of the second“Hodan-kai” meeting can be seen in the web site.2) Following the success of this meeting, we are planning tohold the next meeting in February 2020, and welcome
many young researchers to join.
References
1) https://indico2.riken.jp/event/2509/ .
2) https://indico2.riken.jp/event/2864/ .

Fig. 1. Atmosphere of the 2nd “Hodan-kai” meeting.

∗1∗2

Department of Physics, Kyushu University
RIBF Theory Forum- 245 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 52 (2019)

Symposium on “Science and Technology Explored with Periodic Table”
celebrating the “IYPT2019 in Japan”
H. Sakurai∗1
The year 2019 is the 150th anniversary of Dmitry
Mendeleev’s discovery of the periodic system and has
thus been proclaimed to be the “International Year of
the Periodic Table of Chemical Elements” (IYPT2019)by the United Nations General Assembly and UNESCO1) . As the ﬁrst oﬃcial event at the IYPT2019 inJapan, a kick-oﬀ symposium titled “Science and Technology Explored with Periodic Table” was organized at
the Science Council of Japan (SCJ), Tokyo, on February 23rd , 2019.2)
The symposium was coupled with an opening ceremony to celebrate the IYPT2019. Prof. Ken Sakai,chairman of the SCJ committees of the IYPT2019 and
IUPAC, gave an opening introduction of the event.
Celebration addresses were made by representatives ofhosting and supporting organizations of the symposium, including SCJ, The Chemical Society of Japan,
The Physical Society of Japan, and RIKEN. On behalfof RIKEN, Prof. Shigeo Koyasu, one of the executives,
spoke about the history of RIKEN over a 100 years
and highlighted the contributions made by RIKEN to
the development of the periodic table.
Invited talks related to elements and the periodic table were given by distinguished chemists andphysicists: Profs. Kouhei Tamao, Hideo Hosono,
Susumu Kitagawa, Yoshiteru Maeno, Hiroko Tokoro,
Kousuke Morita, and Kazuyuki Tatsumi. Prof. Morita
presented a history of element ﬁnding and productionand emphasized the role of RIKEN in the productionof Element 113, “Nihonium.”Fig. 2. Group photo of representatives of hosting organization with the speakers and organizers of the opening
ceremony and symposium.

A discussion session was chaired by Prof. Hiroyoshi Sakurai. Questions about elements were raisedby the audience, and answers were provided by speakers and organizers to help the general public understand elements better.
The closing remark was made by Prof. Mihoko Nojiri, vice chairman of the SCJ IYPT2019 committee
and chairman of the SCJ IUPAP committee.
The symposium was open for public and the numberof total participants was about 200, including media
reporters.
The SCJ IYPT2019 committee acknowledges themany people, who supported the organization of theceremony and symposium, as well as the administration and staﬀ members at RIKEN Nishina Centerfor their support: Asako Takahashi, Yunike Shimizu,
Kazushige Fukushima, Tetsuo Nayuki, Keiko Iwano,
Kumiko Sugita, Midori Shishido, Tomomi Okayasu,
Midori Yamamoto, and Mitsue Yamamoto. The symposium poster was designed by Narumasa Miyauchi.
Dr. Ryo Taniuchi was in charge of photography.
References
1) https://www.iypt2019.org .
2) https://www.iypt2019.jp .

Fig. 1. Photo of the IYPT2019 symposium held at the hallof Science Council of Japan on February 23rd , 2019.
∗1

RIKEN Nishina Center- 246 -

VI. ORGANIZATION AND ACTIVITIESOF RIKEN NISHINA CENTER(Activities, Members, Publications & Presentations)Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

1. Organization
1.1 Organization Chart as of March 31, 2019 （End of FY2018）- 247 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

1.2 Topics in FY2018
In FY2018, the RNC reorganized the former three division system consisting of the Theory Research Division, the Subnuclear System
Research Division and the RIBF Research Division into a four division system.
Year

Date

Topics in Management

2018

Apr. 1

Newly appointed:
Team Leader of the SLOWRI Team: Hironobu ISHIYAMA

2018

Apr. 1

Newly appointed:
Team Leader of the Computing and Network Team: Hidetada BABA

2018

May. 1

Newly appointed:
Team Leader of the Plant Genome Evolution Research Team: Yusuke KAZAMA

2019

Jan. 11

Interim Review of the Chief Scientist, Tomohiro UESAKA

2. Finances
A transition of the RNC budget for the past five years is shown in following graph.
Million Yen

3,500
3,000
2,500
2,000
1,500

2,800

3,060

3,199

2016

2017

2,877

1,000
500
0

2015

2018

3. Staffing
At the start of FY 2018, there were 160 personnel affiliated with RNC and 355 researchers visiting RNC for research purpose. The following
graphs show a breakdown of personnel into six categories as of April 1, 2018, and a transition of the number of each category.

73

Permanent Researcher

38

Contract Researcher
Technical staff

355

Special Postdoctoral Researcher
Junior Research Associate
External researcher

FY2018- 248 -

12
18
19

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

700

External researcher

600

Junior Research Associate

500

Special Postdoctoral
Researcher

400
300

Technical staff

200

Contract Researcher

100

Permanent Researcher

0

2015

2016

2017

2018

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

2015

2016

2017

2018

Publication Year

Citation analysis for the past four years
As of March 2019Year
Indicators
Total number of papers

2015

2016

2017

2018

288

347

298

286

Percentage of papers in top 10%

17.01

15.85

16.78

20.63

Percentage of papers in top 1%

1.39

1.44

2.68

4.20

- 249 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 FY2018. 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, 2019)
Hideto EN'YO
Director RNC, Chief Scientist, Director of Radiation Laboratory
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, 2019)
Hideto EN'YO
Director, RNC, Director, Radiation Laboratory
Hiroyoshi SAKURAI
Deputy Director, RNC; Group Director, Radioactive Isotope Physics Laboratory and Nuclear Transmutation Data
Research Group; Team Leader, Muon Date Team
Osamu KAMIGAITO
Deputy Director, RNC; Group Director, Accelerator Group and High-Intensity Accelerator R&D Group; Team
Leader, Infrastructure Management Team
Tomoko ABE
Deputy Director, RNC; Group Director, Beam Mutagenesis Group; Team Leader, Ion Beam Breeding Team
Yasushige YANO
Senior Advisor, RNC
Tohru MOTOBAYASHI
Senior Advisor, RNC
Hideyuki SAKAI
Senior Advisor, RNC
Tomohiro UESAKAGroup Director, Spin Isospin Laboratory and Research Instruments Group
Hideki UENO
Group Director, Nuclear Spectroscopy Laboratory and User Liaison Group; Team Leader, Outreach TeamToru TAMAGAWA
Group Director, High Energy Astrophysics Laboratory
Kosuke MORITA
Group Director, Superheavy Element Research Group
Yuko MOTIZUKIGroup Director, Astro-Glaciology Research Group
Hiroki OKUNO
Deputy Group Director, Accelerator Group; Team Leader, Accelerator R&D Team, Cryogenic Technology Team, andHigh-Power Target R&D Team
Nobuhisa FUKUNISHI
Deputy Group Director, Accelerator Group; Team Leader, Beam Dynamics & Diagnostics Team
Masanori WAKASUGIGroup Director, Instrumentation Development Group; Team Leader, Rare RI-Ring Team and SCRIT Team
Hiromitsu HABA
Group Director, RI Application Research Group; Team Leader, RI Application Team and Superheavy Element- 250 -

Ⅵ. RNC ACTIVITIES

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
Yusuke KAZAMA
Atsushi YOSHIDA
Yasuyuki AKIBA
Taku IZUBUCHI
Ken-ichiro YONEDA
Tsukasa TADA
Yutaka WATANABE
Yasushi WATANABE
Teruo NAYUKI

RIKEN Accel. Prog. Rep. 52 (2019)
Production TeamGroup Director, Quantum Hadron Physics Laboratory
Group Director, Strangeness Nuclear Physics Laboratory
Group Director, Meson Science Laboratory
Group 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, Plant Genome Evolution Research Team
Team Leader, Industrial Application Research TeamGroup Leader, Experimental Group, RIKEN BNL Research Center
Group Leader, Computing Group, RIKEN BNL Research Center
Team Leader, RIBF User Liaison Team
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 19th NP-PAC was held on November 29−December 1, 2018 at RIBF.
Members (as of March 31, 2019)
Angela BRACCO (Chair)
Dieter ACKERMANN
Andrei ANDREYEV
Ikuko HAMAMOTO
Robert V.F. JANSSENS
Augusto O. MACCHIAVELLIDavid J. MORRISSEY
Tomofumi NAGAE
Hitoshi NAKADA
Alexandre OBERTELLI
Kazuyuki OGATA
Tomas RAUSCHER
Kimiko SEKIGUCHIHaik SIMON
Piet VAN DUPPEN
Yuhu ZHANG

INFN
GANIL
University of York
Lund University
University of North Carolina at Chapel Hill
Lawrence Berkeley National Laboratory
Michigan State University
Kyoto University
Chiba University
Technische Universität Darmstadt
RCNP, Osaka University
University of Basel
Tohoku University
GSI
K.U.Leuven
Institute of Modern Physics, CAS

Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)
The 16th and 17th ML-PAC was held on July 20, 2018 and January 2019 at RIBF, respectively.
Members (as of March 31, 2019)
Adrian HILLIER (Chair)Toshiyuki AZUMA
Ryosuke KADONO
Atsushi KAWAMOTO
Norimichi KOJIMA
Kenya KUBO
Philippe MENDELSISIS, RAL (UK)RIKEN Cluster for Pioneering ResearchInstitute of Materials Structure Science (KEK)
Hokkaido University
Toyota RIKEN
ICU
Universite Paris-SUD(France)- 251 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)
Atsushi SHINOHARA
Shukri SULAIMAN
Hiroyuki YAMASE
Shigeo YOSHIDA
Xu-Guang ZHENG

Osaka University
Universiti Sains Malaysia (Malaysia)
NIMS
Thera-Projects
Saga University

Industrial Program Advisory Committee (In-PAC)
The 8th In-PAC was held on June 29, 2018 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, 2019)
Hiromi SATO (Chair)
Kouji MORIMOTO
Eiji IKEZAWA
Hiromitsu HABA
Shinichiro MICHIMASA
Hidetoshi YAMAGUCHI
Yutaka WATANABE
Atsushi YOSHIDA
Koichi YOSHIDA
Naoki FUKUDA
Naruhiko SAKAMOTO
Daisuke SUZUKI
Juzo ZENIHIROYuichi ICHIKAWA

Team Leader, Detector Team
Team Leader, Superheavy Element Device Development Team
Team Leader, RILAC Team
Team Leader, RI Application Team
Assistant Prof., Center for Nuclear Study, University of Tokyo
Lecturer, Center for Nuclear Study, University of Tokyo
Associate Professor, High Energy Accelerator Research Organization, KEK
Team Leader, Industrial Cooperation Team
Team Leader, BigRIPS Team
Nishina Center Research Scientist, BigRIPS Team
Team Leader, Cyclotron Team
Research Scientist, Radioactive Isotope Physics Laboratory
Research Scientist, Spin Isospin Laboratory
Research Scientist, Nuclear Spectroscopy Laboratory

Ex officio members
Kanenobu TANAKA
Hisao SAKAMOTOGroup Director, Safety Management Group
Technical Scientist, Safety Management Group

Hot-Lab Safety Review Committee
Members (as of March 31, 2019)
Masako IZUMI (Chair)
Kanenobu TANAKA
Hisao SAKAMOTO
Hiroki MUKAI
Eriko HIGURASHI
Hiromitsu HABA

Senior Research Scientist, Ion Beam Breeding TeamGroup Director, Safety Management Group
Safety Management Group
Technical Staff I, Assigned Employee, Safety Management Group
Technical Scientist, Safety Management GroupTeam Leader, RI Application 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, 2019)
Hideki UENO (Chair)
Osamu KAMIGAITO
Masanori WAKASUGITomohiro UESAKA
Nobuhisa FUKUNISHI
Hiroki OKUNO
Hiroyoshi SAKURAI
Tomoko ABE
Hiromitsu HABA
Kanenobu TANAKA
Ken-ichiro YONEDA

Group Director, User Liaison and Industrial Cooperation Group and Nuclear Spectroscopy Laboratory
Group Director, Accelerator Group
Group Director, Instrumentation Development Group
Group Director, Research Instruments Group and Spin Isospin Laboratory
Deputy Group Director, Accelerator Group
Deputy Group Director, Accelerator Group
Group Director, Radioactive Isotope Physics Laboratory
Group Director, Beam Mutagenesis Group
Group Director, RI Application Research Group
Group Director, Safety Management GroupTeam Leader, RIBF User Liaison Team- 252 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Kouji MORIMOTO
Koichi YOSHIDATeam Leader, Superheavy Element Research Device Development Team
Team Leader, BigRIPS Team

External members
Kentaro YAKO
Hidetoshi YAMAGUCHI
Michiharu WADA

Associate Professor, Center for Nuclear Study, University of Tokyo
Lecturer, Center for Nuclear Study, University of Tokyo
Professor, High Energy Accelerator Research Organization, KEK

ObserversHideto EN'YO
Susumu SHIMOURA
Hiroari MIYATAKE

Director, RNC
Director, Center for Nuclear Study, University of Tokyo
Director, KEK Wako Nuclear Science Center

Kosuke MORITA
Hideaki OTSU
Atsushi YOSHIDA
Tohru MOTOBAYASHI
Kazushige FUKUSHIMAGroup Director, Superheavy Element Research GroupTeam Leader, SAMURAI Team
Team Leader, Industrial Cooperation Team
Senior Advisor, RNCManager, Nishina Center and iTHMES 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, 2019)
Teruo NAYUKI
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; Group Director, Radioactive Isotope Physics Laboratory
Deputy Director, RNC; Group Director, Accelerator Group
Deputy Director, RNC; Group Director, Beam Mutagenesis Group
Group Director, Quantum Hadron Physics Laboratory
Group Director, Meson Science Laboratory
Group Director, Spin Isospin Laboratory and Research Instruments Group
Group Director, Nuclear Spectroscopy Laboratory and User Liaison Group
Group Director, High Energy Astrophysics Laboratory
Group Director, Strangeness Nuclear Physics Laboratory
Group 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 24th MSC was held on June 12, 2018.
Members (as of June 12, 2018)
Motoko KOTANIShoji NAGAMIYA
Tetsuo HATSUDA
Robert TRIBBLEDavid LISSAUER
Berndt MUELLER

Executive Director, RIKEN
Senior Visiting Scientist, RNC
Program Director, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program
Deputy Director for Science and Technology, BNL
Deputy Chair, Physics Department, BNL
Associate Laboratory Director for Nuclear and Particle Physics, BNL

6. International Collaboration

Country
China

Partner InstituteObjects

RNC contact person

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- 253 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 ionsTohru MOTOBAYASHI, Senior Advisor, RNC

Germany

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

Italy

Applied Physics Division,
National Institute for New
Technologies, Energy andEnvironment (ENEA)

Framework

Tohru MOTOBAYASHI, Senior Advisor, RNC

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

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

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

RussiaJoint 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

Korea- 254 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Switzerland

Paul Scherrer InstituteImprove the performance and reliability ofaccelerator systems

Osamu KAMIGAITO, Director, Accelerator GroupUK

The Science and Technology
Facilities Council

Muon science using the ISIS Facility at the
Rutherford Appleton Laboratory

Masahiko IWASAKI, Director, Meson Science
Laboratory

USA

BNL

The Spin Physics Program at the Relativistic
Heavy Ion Collider (RHIC)

Hideto EN’YO, Director, Radiation Laboratory

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

Vietnam Atomic Energy
Commission

Framework

Tohru MOTOBAYASHI Senior Advisor, RNC

Institute of Physics, Vietnam
Academy of Science andTechnology

Framework

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

European Nuclear Science andApplication
Research2

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Vietnam

Europe7. Awards
Awardee, Laboratory / TeamAward

Organization

Date

Hiroki OKUNO, Deputy Group Director, Accelerator
Group
Kensuke KUSAKA, Nishina Center Research Scientist,
BigRIPS TeamThe 22nd Superconductivity Scienceand Technology Award

Forum of Superconductivity Scienceand Technology

Apr. 16

Hideaki OTSU, Team Leader, Fast RI Data Team
Hiroyoshi SAKURAI, Team Leader, Muon Date Team
Teiichiro MATSUZAKI, Contract Researcher, Muon Data
TeamThe 21st Century Invention PrizeJapan Institute Invention andInnovation

Jun. 12

Minjung KIM, Intern, Radiation Laboratory2018 Gertrude Scharff-Goldhabor
Prize

Brookhaven Woman in Science(BWIS)

Jul. 17

Yuya TANIZAKI, Special Postdoctoral Researcher,
Theory Group, RIKEN BNL Research Center

The 13th Particle Physics
Medal(FY2018): Young Scientist
Award in Theoretical Particle Physics

Particle Theory Committee

Sep. 16

Taku IZUBUCHI, Group Leader, Computing Group,
RIKEN BNL Research Center

APS Fellow

American Physical Society

Sep. 11

Naoki KIMURA, Student Trainee, SLOWRI TeamThe 2018 International Conference
Presentation Incentive Award

The Atomic Collision Society of Japan

Jun. 18

Masato NAKAMURA, Senior Technical Scientist,
Cryogenic Technology TeamThe Saitama prefecture High-pressure
Gas Chairman Commendation

The Saitama prefecture High-pressure
Gas Committee

Oct. 16

Takahiro NISHI, Postdoctoral Researcher, Spin Isospin
Laboratory

The 13th Young Scientist Award of
the Physical Society of Japan in thefield of experimental physics/The 25thAward for Outstanding Young
Physicists-Experimental Nuclear
Physics

The Physical Society of Japan

Mar. 15- 255 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

8. Brief overview of the RI Beam Factory
Intensity of Primary Beams
Achieved beam intensities (as of March 2018)
238

U
Xe
86
Kr
78
Kr
70
Zn
48
Ca
18
O
14
N
4
He
d
pol. d124

70 pnA (345 MeV/nucleon, Nov. 2017)
102 pnA (345 MeV/nucleon, Apr. 2016)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- 256 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Total beam time for experiments

Total beam time allocated to BigRIPS experiments- 257 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 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.
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.
A new project of high resolution gamma spectroscopy with fast beams has been proposed at PAC 2018 and the campaign programs
are scheduled in 2020. MINIBALL and several Ge tracking detectors from Japan, Europe and the USA are being combined to form
an array of germanium detectors. The new setup aims to accelerate researches of the nuclear structure by observing gamma-lines
in even-odd nuclei and measuring lifetimes of excited states. The first workshop will be organized in April, 2019, and having 55
participants.
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
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.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 have been conducted for programs approved to survey nuclei of interest as many as possible, such as Ni-78, Pd-128,
Sn-100. So far, 44 papers including 12 PRL’s and 10 PLB’s were published. One of the highlights is discovery of a seniority isomer in
Pd-128, of which cascade gamma decay gives the energy of first excited state and robustness of N = 82 magic number, and the otheris a half-life measurement for 110 neutron-rich nuclei across the N = 82 shell gap, which shows implications for the mechanism anduniversality of the r-process path. The EURICA collaboration finished its physics programs in summer 2016.
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 and 2018.
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 program to find out proton-cluster states was organized by utilizing
low-energy radioactive isotope beams at GANIL-LISE, where the RIKEN liquid hydrogen target was installed.
A new project based on missing mass spectroscopy was launched to investigate an exotic cluster state in a very proton-rich nucleus.
The experiment will be 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)

Contract Researcher
Mizuki NISHIMURA
Research Consultants
Masayasu ISHIHARA
Hiroyuki MURAKAMI
Akitsu IKEDA

Kenichi MATSUYANAGI
Kenji TANABE- 259 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Special Postdoctoral Researcher
Browne FRANK

Shintaro GO

Foreign Postdoctoral Researcher
He WANG
Research Associate
Ryo TANIUCHI
Junior Research Associates
Masanori KANEKO (Kyoto Univ.)

Hideki SHIMIZU (Univ. of Tokyo)

International Program Associates
Xiaohui SUN (Peking Univ.)

Phong VI (VNU Universityof Science)of Science)

Visiting Researcher
Benoit Jean-Pacal Camille MAUSS (JSPS Fellow)
Senior Visiting Scientists
Kengo OGAWA (Chiba Univ.)
Shigeru KUBONO (Univ. of Tokyo)

Koichiro ASAHI (Tokyo Tech)

Visiting Scientists
Hooi Jing ONG (RCNP)
Akira ONO (Tohoku Univ.)
Megumi NIIKURA (Univ. of Tokyo)
Kazuhiro OYAMATSU (Aichi Shukutoku University)
Silivio CHERUBINI (Univ. of Catania)
Clementine SANTAMARIA (Berkeley Lab.)
Daiki NISHIMURA (Tokyo Univ. of Sci.)
Kei IIDA (Kochi University)
Takashi KISHIDA (Aoyama Univ.)
Gabor KISS (MTA Atomki)
Naohiko OTSUKA (Intl. Atomic Energy Agency, Austria)
Natsumi IKENO (Tottori Univ.)
Giuseppe LORUSSO (National Physics Lab., UK)
Giordano CERIZZA (NSCL)
Hiu Ching LEE (Univ. of Hong Kong)
Satoshi TAKEUCHI (Tokyo Tech)
Byungsik HONG (Korea Univ.)
Paer-Anders SOEDERSTROEM (T. U. Darmstadt)

Alan MCINTOSH (Texas A & M Univ.)
Jin WU (ANL)
Kathrin WIMMER (Univ. of Tokyo)
Jin-hee CHANG (MSU)
Tetsuya MURAKAMI (Kyoto Univ.)
Yoshiharu MORI (Kyoto univ.)
Kazuo IEKI (Rikkyo Univ.)
Rensheng WANG (Soochow Univ.)
Mitsunori FUKUDA (Osaka Univ.)
Takuji IZUMIKAWA (Niigata Univ.)
Nori AOI (RCNP)
Takashi OHTSUBO (Niigata Univ.)
Khiem Hong LE (Vietnam Academy of Sci. and Tech.)Maya TAKECHI (Niigata Univ.)
Evgueni NIKOLSKI (RRC Kurchatov Inst.)
Martha Liliana CORTES SUA (INFN)
Hiroshi WATANABE (Beihang Univ.)
Alexey OGLOBLIN(Kurchatov Institute)

Visiting Technicians
Ivan KOJOUHAROV (GSI)

Jorge AGRAMUNT ROS (Valencia City Hall)

Student Trainees
Akira HOMMA (Niigata Univ.)
Tomohito AMANO (Univ. of Tokyo)
Satoru MOMIYAMA (Univ. of Tokyo)
Natsumi OGAWA (Univ. of Tokyo)
Justin ESTEE (Michigan State University)
Naoya YOSHIDA (Univ. of Tokyo)
JungWoo LEE (Korea University)
Rento YAMADA (Univ. of Tokyo)
Shunpei KOYAMA (Univ. of Tokyo)
Jun TSUTSUMI (Univ. of Tokyo)
Jonathan BARNEY (Michigan State University)
Zhulieta TONEVA (University of Sofia St. Kl. Ohridski)
Shinnosuke KANAYA (Osaka Univ.)

Noritsugu NAKATSUKA(Kyoto Univ.)
Takeshi SAITO (Univ. of Tokyo)
Ayumi YAGI(Osaka Univ.)
Takuma KOIWAI (Univ. of Tokyo)
Kosuke ONISHI(Osaka Univ.)
Yusuke FUJINO (Rikkyo Univ.)
Takanobu SUGIHARA(Osaka Univ.)(Hanoiof
University
Phong VI (VNU
Science) of Science)
Naoto KANDA(Niigata Univ.)
Linh BUI (Vietnam Atomic Energy Institute)
So SATO(Rikkyo Univ.)
Takamichi AOKI (Univ. of Tokyo)
Moe NAKANO(Rikkyo Univ.)

Part-time Worker
Keishi MATSUI (Univ. of Tokyo)- 260 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
H. L. Crawford, P. Fallon, A. O. Macchiavelli, P. Doornenbal, N. Aoi, F. Browne, C. M. Campbell, S. Chen, R. M. Clark, M. L. Cortes,
M. Cromaz, E. Ideguchi, M. D. Jones, R. Kanungo, M. MacCormick, S. Momiyama, I. Murray, M. Niikura, S. Paschalis, M. Petri,
H. Sakurai, M. Salathe, P. Schrock, D. Steppenbeck, S. Takeuchi, Y. K. Tanaka, R. Taniuchi, H. Wang, K. Wimmer, “First spectroscopyof the near drip-line nucleus 40 Mg,” Phys. Rev. Lett. 122, 052501 (2019).
P. J. Davies, J. Park, H. Grawe, R. Wadsworth, R. Gernhauser, R. Krucken, F. Nowacki, D. S. Ahn, F. Ameil, H. Baba, T. Back, B. Blank,
A. Blazhev, P. Boutachkov, F. Browne, I. Celikovic, M. Dewald, P. Doornenbal, T. Faestermann, Y. Fang, G. de France, N. Fukuda,
A. Gengelbach, J. Gerl, J. Giovinazzo, S. Go, N. Goel, M. Gorska, 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. Soderstrom, K. Steiger, T. Sumikama,
H. Suzuki, H. Takeda, J. Taprogge, P. Thole, S. Valder, Z. Wang, N. Warr, H. Watanabe, V. Werner, J. Wu, Z. Y. Xu, A. Yagi,
K. Yoshinaga, Y. Zhu, “Toward the limit of nuclear binding on the N = Z line: Spectroscopy of 96 Cd,” Phys. Rev. C 99, 021302 (2019).
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, Z. Xu, “Nuclear
structure of 76 Ni from the (p, 2p) reaction,” Phys. Rev. C 99, 014312 (2019).
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. Chateau, S. Chen, N. Chiga, A. Corsi, M. L. 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. 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. Soderstrom, S. Takeuchi, H. Tornqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada,
D. Yan, Z. Yang, M. Yasuda, L. Zanetti, “How robust is the N = 34 subshell closure? First spectroscopy of 52 Ar,” Phys. Rev. Lett. 122,
072502 (2019).
I. Murray, M. MacCormick, D. Bazin, P. Doornenbal, N. Aoi, H. Baba, H. Crawford, P. Fallon, K. Li, J. Lee, M. Matsushita, T. Motobayashi, T. Otsuka, H. Sakurai, H. Scheit, D. Steppenbeck, S. Takeuchi, J. A. Tostevin, N. Tsunoda, Y. Utsuno, H. Wang, K. Yoneda,“Spectroscopy of strongly deformed 32 Ne by proton knockout reactions,” Phys. Rev. C 99, 011302 (2019).
J. Park, R. Krucken, D. Lubos, R. Gernhauser, M. Lewitowicz, S. Nishimura, D. S. Ahn, H. Baba, B. Blank, A. Blazhev, P. Boutachkov,
F. Browne, I. Celikovic, G. de France, P. Doornenbal, T. Faestermann, Y. Fang, N. Fukuda, J. Giovinazzo, N. Goel, M. Gorska,
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. Patel, M. M. Rajabali, S. Rice, H. Sakurai, H. Schaﬀner, Y. Shimizu, L. Sinclair,
P. -A. Soderstrom, K. Steiger, T. Sumikama, H. Suzuki, H. Takeda, Z. Wang, H. Watanabe, J. Wu, Z. Y. Xu, “New and comprehensive
beta- and betap-decay spectroscopy results in the vicinity of 100 Sn,” Phys. Rev. C 99, 034313 (2019).
V. Vaquero, A. Jungclaus, P. Doornenbal, K. Wimmer, A. M. Moro, K. Ogata, T. Furumoto, S. Chen, E. Nacher, E. Sahin, Y. Shiga,
D. Steppenbeck, R. Taniuchi, Z. Y. Xu, T. Ando, H. Baba, F. L. Bello Garrote, S. Franchoo, K. Hadynska-Klek, A. Kusoglu, J. Liu,
T. Lokotko, S. Momiyama, T. Motobayashi, S. Nagamine, N. Nakatsuka, M. Niikura, R. Orlandi, T. Y. Saito, H. Sakurai, P. A. Soderstrom, G. M. Tveten, Zs. Vajta, M. Yalcinkaya, “In-beam gamma-ray spectroscopy of 136 Te at relativistic energies,” Phys. Rev. C 99,
034306 (2019).
K. Wimmer, F. Recchia, S. M. Lenzi, S. Riccetto, T. Davinson, A. Estrade, C. J. 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. R. John, D. Kahl, G. Kiss, I. Kojouharov, N. Kurz, M. Labiche, K. Matsui, S. Momiyama, D. R. Napoli, M. Niikura, C. Nita,
Y. Saito, H. Sakurai, H. Schaﬀner, P. Schrock, C. Stahl, T. Sumikama, V. Werner, W. Witt, P. J. Woods, “First spectroscopy of 61 Ti andthe transition to the island of inversion at N = 40,” Phys. Lett. B 792, 16 (2019).
H. Sakurai, “Nuclear physics with RI Beam Factory,” Front. Phys. 13, 132111 (2018).
M. L. Cortes, P. Doornenbal, M. Dupuis, S. M. Lenzi, F. Nowacki, A. Obertelli, S. Peru, N. Pietralla, V. Werner, K. Wimmer, G. Authelet,
H. Baba, D. Calvet, F. Chateau, A. Corsi, A. Delbart, J.-M. Gheller, A. Gillibert, T. Isobe, V. Lapoux, C. Louchart, 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, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, F. Browne, L. X. Chung, Zs. 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, L. Olivier, S. Ota, Z. Patel, E. Sahin, C. M. Shand, P-A. Soderstrom, I. Stefan, D. Steppenbeck,
T. Sumikama, D. Suzuki, Zs. Vajta, J. Wu, Z. Xu, “Inelastic scattering of neutron-rich Ni and Zn isotopes oﬀ a proton target,” Phys.
Rev. C 97, 044315 (2018).
A. Corsi, A. Obertelli, P. Doornenbal, F. Nowacki, H. Sagawa, Y. Tanimura, N. Aoi, H. Baba, P. Bednarczyk, S. Boissinot, M. Ciemala,A. Gillibert, T. Isobe, A. Jungclaus, V. Lapoux, J. Lee, K. Matsui, M. Matsushita, T. Motobayashi, D. Nishimura, S. Ota, E. Pollacco,- 261 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

H. Sakurai, C. Santamaria, Y. Shiga, D. Sohler, D. Steppenbeck, S. Takeuchi, R. Taniuchi, H. Wang, “Spectroscopy of nuclei around
100Sn populated via two-neutron knockout reactions,” Phys. Rev. C 97, 044321 (2018).
X. Y. Liu, Z. Liu, B. Ding, P. Doornenbal, A. Obertelli, S. M. Lenzi, P. M. Walker, L. X. Chung, B. D. Linh, 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, M. Niikura, F. Nowacki, H. Otsu, C. Peron, A. Peyaud, E. C. Pollacco, J. -Y. Rousse, H. Sakurai, M. Sasano, Y. Shiga,
S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, Y. H. Lam, T. H. Huang, M. D. Sun, W. Q. Zhang, H. Y. Lu, D. S. Hou,F. Browne, Zs. 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.-A. Soderstrom, G. L. Stefan, D. Steppenbeck, T. Sumikama, D. Suzuki, Zs. Vajta, V. Werner, J. Wu, Z. Xu, X. H. Zhou,
Y. H. Zhang, H. S. Xu, F. S. Zhang, “Spectroscopy of 65, 67–25 Mn: Strong coupling in the N = 40 ‘island of inversion’,” Phys. Lett. B
784, 392 (2018).
J. Park, R. Krucken, D. Lubos, R. Gernhauser, M. Lewitowicz, S. Nishimura, D. S. Ahn, H. Baba, B. Blank, A. Blazhev, P. Boutachkov,
F. Browne, I. Celikovic, G. de France, P. Doornenbal, T. Faestermann, Y. Fang, N. Fukuda, J. Giovinazzo, N. Goel, M. Gorska,
H. Grawe, S. Ilieva, N. Inabe, T. Isobe, A. Jungclaus, D. Kameda, G. D. Kim, Y. -K. Kim, I. Kojouharov, T. Kubo, N. Kurz, G. Lorusso,
K. Moschner, D. Murai, I. Nishizuka, Z. Patel, M. M. Rajabali, S. Rice, H. Sakurai, H. Schaﬀner, Y. Shimizu, L. Sinclair, P.-A. Soderstrom, K. Steiger, T. Sumikama, H. Suzuki, H. Takeda, Z. Wang, H. Watanabe, J. Wu, Z. Y. Xu, “beta decays of the heaviest N = Z − 1nuclei and proton instability of 97 In,” Phys. Rev. C 97, 051301R (2018).
O. B. Tarasov, D. S. Ahn, D. Bazin, N. Fukuda, A. Gade, M. Hausmann, N. Inabe, S. Ishikawa, N. Iwasa, K. Kawata, T. Komatsubara,
T. Kubo, K. Kusaka, D. J. Morrissey, M. Ohtake, H. Otsu, M. Portillo, T. Sakakibara, H. Sakurai, H. Sato, B. M. Sherrill, Y. Shimizu,
A. Stolz, T. Sumikama, H. Suzuki, H. Takeda, M. Thoennessen, H. Ueno, Y. Yanagisawa, K. Yoshida, “Discovery of 60 Ca and implications for the stability of 70 Ca,” Phys. Rev. Lett. 121, 022501 (2018).
Zs. Vajta, D. Sohler, Y. Shiga, K. Yoneda, K. Sieja, D. Steppenbeck, Zs. Dombradi, N. Aoi, P. Doornenbal, J. Lee, H. Liu, M. Matsushita,
S. Takeuchi, H. Wang, H. Baba, P. Bednarczyk, Zs. Fulop, S. Go, T. Hashimoto, E. Ideguchi, K. Ieki, K. Kobayashi, Y. Kondo,
R. Minakata, T. Motobayashi, D. Nishimura, H. Otsu, H. Sakurai, Y. Sun, A. Tamaii, R. Tanaka, Z. Tian, T. Yamamoto, X. Yang,
Z. Yang, Y. Ye, R. Yokoyama, J. Zenihiro, “Proton single particle energies next to 78 Ni: Spectroscopy of 77 Cu via single proton
knock-out reaction,” Phys. Lett. B 782, 99 (2018).
K. Wimmer, W. Korten, T. Arici, P. Doornenbal, 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. T. Doherty, J. Gerl, R. Gernhauser, D. Jenkins, S. Koyama, T. Motobayashi, S. Nagamine,
M. Niikura, A. Obertelli, D. Lubos, B. Rubio, E. Sahin, T. Y. Saito, H. Sakurai, L. Sinclair, D. Steppenbeck, R. Taniuchi, R. Wadsworth,
M. Zielinska, “Shape coexistence and isospin symmetry in A = 70 nuclei: Spectroscopy of the T − Z = 1 nucleus 70 Kr,” Phys. Lett. B
785, 441 (2018).
O. Wieland, A. Bracco, F. Camera, R. Avigo, H. Baba, N. Nakatsuka, T. Aumann, S. R. Banerjee, G. Benzoni, K. Boretzky, C. Caesar,
S. Ceruti, S. Chen, F. C. L. Crespi, V. Derya, P. Doornenbal, N. Fukuda, A. Giaz, K. Ieki, N. Kobayashi, Y. Kondo, S. Koyama, T. Kubo,
M. Matsushita, B. Million, T. Motobayashi, T. Nakamura, M. Nishimura, H. Otsu, T. Ozaki, A. T. Saito, H. Sakurai, H. Scheit,
F. Schindler, P. Schrock, Y. Shiga, M. Shikata, S. Shimoura, D. Steppenbeck, T. Sumikama, S. Takeuchi, R. Taniuchi, Y. Togano,
J. Tscheuschner, J. Tsubota, H. Wang, K. Wimmer, K. Yoneda, “Low-lying dipole response in the unstable 70 Ni nucleus,” Phys. Rev. C
98, 064313 (2018).
R. Yokoyama, E. Ideguchi, G. S. Simpson, Mn. Tanaka, S. Nishimura, P. Doornenbal, G. Lorusso, P. -A. Soderstrom, T. Sumikama,J. Wu, Z. Y. Xu, N. Aoi, H. Baba, F. L. Bello Garrote, G. Benzoni, F. Browne, R. Daido, Y. Fang, N. Fukuda, A. Gottardo, G. Gey,
S. Go, N. Inabe, T. Isobe, D. Kameda, K. Kobayashi, M. Kobayashi, I. Kojouharov, T. Komatsubara, T. Kubo, N. Kurz, I. Kuti,
Z. Li, M. Matsushita, S. Michimasa, C. B. Moon, H. Nishibata, I. Nishizuka, A. Odahara, Z. Patel, S. Rice, E. Sahin, H. Sakurai,
H. Schaﬀner, L. Sinclair, H. Suzuki, H. Takeda, J. Taprogge, Zs. Vajta, H. Watanabe, A. Yagi, T. Inakura, “Beta-gamma spectroscopyof the neutron-rich 150 Ba,” Prog. Theor. Exp. Phys. 2018, 041D02 (2018).
S. Hatakeyama, W. Horiuchi, A. Kohama, “Nuclear surface diﬀuseness revealed in nucleon-nucleus diﬀraction,” Phys. Rev. C 97, 054607(2018).
B. C. Rasco, N. T. Brewer, R. Yokoyama, R. Grzywacz, K. P. Rykaczewki, A. Tolosa-Delgado, J. Agramunt, J. L. Taı́n, A. Algora,
O. Hall, C. Griﬃn, T. Davinson, V. H. Phong, J. Liu, S. Nishimura, G. G. Kiss, N. Nepal, A. Estrade, “The ORNL analysis techniquefor extracting β-delayed multi-neutron branching ratios with BRIKEN,” Nucl. Instrum. Methods Phys. Res. A 911, 79 (2018).
A. I. Morales, G. Benzoni, H. Watanabe, G. de Angelis, S. Nishimura, L. Coraggio, A. Gargano, N. Itaco, T. Otsuka, Y. Tsunoda,
P. Van Isacker, F. Browne, R. Daido, P .Doornenbal, Y. Fang, G. Lorusso, Z. Patel, S. Rice, L. Sinclair, P Söderström, T. Sumikama,J. J. Valiente-Dobón, J. Wu, Z. Y. Xu, A. Yagi, R. Yokoyama, H. Baba, R. Avigo, F. L. Bello Garrote, N. Blasi, A. Bracco,
A. M. Bruce, F. Camera, S. Ceruti, F. C. L. Crespi, M. -C. Delattre, Zs. Dombradi, A. Gottardo, T. Isobe, I. Kojouharov, N. Kurz,
I. Kuti, S. Lalkovski, K. Matsui, B. Melon, D. Mengoni, T. Miyazaki, V. Modamio-Hoybjor, S. Momiyama, D. R. Napoli, M. Niikura,
R. Orlandi, Zs. Podolyák, P. H. Regan, H. Sakurai, E. Sahin, D. Sohler, H. Schaﬀner, R. Taniuchi, J. Taprogge, Zs. Vajta, O. Wieland,
M. Yalcinkay, “Is seniority a partial dynamic symmetry in the first νg9/2 shell?,” Phys. Lett. B 781, 706 (2018).
VI Ho Phong, S. Nishimura, Le Hong Khiem, “Evaluation of simultaneous fitting method for β-decay half-lives and β-delayed multineutron emission probabilities developed for the BRIKEN experiment,” Commun. Phys. 28, 311 (2018).
T. Isobe, G. Jhang, H. Baba, J. Barney, P. Baron, G. Cerizza, J. Estee, M. Kaneko, M. Kurata-Nishimura, J. W. Lee, W. G. Lynch,
T. Murakami, N. Nakatsuka, E. C. Pollacco, W. Powell, H. Sakurai, C. Santamaria, D. Suzuki, S. Tangwancharoen, M. B. Tsang,“Application of the Generic Electronics for Time Projection Chamber (GET) readout system for heavy radioactive isotope collisionexperiments,” Nucl. Instrum. Methods Phys. Res. A 899, 43 (2018).
E. C. Pollacco, G. F. Grinyer, F. Abu-Nimeh, T. Ahn, S. Anvar, A. Arokiaraj, Y. Ayyad, H. Baba, M. Babo, P. Baron, D. Bazin, S. BeceiroNovo, C. Belkhiria, M. Blaizot, B. Blank, J. Bradt, G. Cardella, L. Carpenter, S. Ceruti, E. De Filippo, E. Delagnes, S. De Luca,- 262 -

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H. De Witte, F. Druillole, B. Duclos, F. Favela, A. Fritsch, J. Giovinazzo, C. Gueye, T. Isobe, P. Hellmuth, C. Huss, B. Lachacinski,
A. T. Laﬀoley, G. Lebertre, L. Legeard, W. G. Lynch, T. Marchi, L. Martina, C. Maugeais, W. Mittig, L. Nalpas, E. V. Pagano,
J. Pancin, O. Poleshchuk, J. L. Pedroza, J. Pibernat, S. Primault, R. Raabe, B. Raine, A. Rebii, M. Renaud, T. Roger, P. RousselChomaz, P. Russotto, G. Saccà, F. Saillant, P. Sizun, D. Suzuki, J. A. Swartz, A. Tizon, N. Usher, G. Wittwer, J. C. Yang, “GET: A
generic electronics system for TPCs and nuclear physics instrumentation,” Nucl. Instrum. Methods Phys. Res. A 887, 81–93 (2018).
D. Kahl, H. Yamaguchi, S. Kubono, A. A. Chen, A. Parikh, D. N. Binh, J. Chen, S. Cherubini, N. N. Duy, T. Hashimoto, S. Hayakawa,
N. Iwasa, H. S. Jung, S. Kato, Y. K. Kwon, S. Nishimura, S. Ota, K. Setoodehnia, T. Teranishi, H. Tokieda, T. Yamada, C. C. Yun,
L. Y. Zhang, “First measurement of 30 S + α resonant elastic scattering for the 30 S(α, p) reaction rate,” Phys. Rev. C 97, 015802 (2018).
H. Muto, Y. Ohshiro, Y. Kotaka, H. Yamaguchi, Y. Sakemi, K. Kobayashi, M. Nishimura, M. Oyaizu, S. Kubono, M. Kase, T. Hattori,
S. Shimoura, “Note: An innovative method for 12 C4+ suppression in 18 O6+ beam production in an electron cyclotron resonance ion
source (selected as the editor’s pick),” Rev. Sci. Instrum. 89, 016103 (2018).
Y. M. Xing, K. A. Li, Y. H. Zhang, X. H. Zhou, M. Wang, Yu. A. Litvinov, K. Blaum, S. Wanajo, S. Kubono, G. Martı́nez-Pinedo,
A. Sieverding, R. J. Chen, P. Shuai, C. Y. Fu, X. L. Yan, W. J. Huang, X. Xu, X. D. Tang, H. S. Xu, T. Bao, X. C. Chen, B. S. Gao,J. J. He, Y. H. Lam, H. F. Li, J. H. Liu, X. W. Ma, R. S. Mao, M. Si, M. Z. Sun, X. L. Tu, Q. Wang, J. C. Yang, Y. J. Yuan, Q. Zeng,
P. Zhang, X. Zhou, W. L. Zhan, S. Litvinov, G. Audi, T. Uesaka, Y. Yamaguchi, T. Yamaguchi, A. Ozawa, C. Fröhlich, T. Rauscher,
F.-K. Thielemann, B. H. Sun, Y. Sun, A. C. Dai, F. R. Xu, “Mass Measurements of neutron-deficient Y, Zr, and Nb isotopes and theirimpact on rp and νp nucleosynthesis processes,” Phys. Lett. B 781, 358–363 (2018).
C. Y. Fu, Y. H. Zhang, X. H. Zhou, M. Wang, Yu. A. Litvinov, K. Blaum, H. S. Xu, X. Xu, P. Shuai, Y. H. Lam, R. J. Chen, X. L. Yan,
T. Bao, X. C. Chen, H. Chen, J. J. He, S. Kubono, D. W. Liu, R. S. Mao, X. W. Ma, M. Z. Sun, X. L. Tu, Y. M. Xing, P. Zhang, Q. Zeng,
X. Zhou, W. L. Zhan, S. Litvinov, G. Audi, T. Uesaka, Y. Yamaguchi, T. Yamaguchi, A. Ozawa, B. H. Sun, Y. Sun, F. R. Xu, “Massesof the T z = −3/2 nuclei 27 P and 29 S,” Phys. Rev. C 98, 014315 (2018).
D. Kim, G. W. Kim, S. Y. Park, A. Kim, K. I. Hahn, K. Abe, O. Beliuskina, S. Hayakawa, N. Imai, N. Kitamura, Y. Sakaguchi, H. Yamaguchi, S. M. Cha,K. Y. Chae, M. S. Kwag, S. W. Hong, E. J. Lee, J. H. Lee, E. K. Lee, J. Y. Moon, S. H. Bae, S. H. Choi, S. Kubono,
V. Panin, Y. Wakabayashi, N. Iwasa, D. Kahl, A. A. Chen, “Study of 19 F levels with Ex = 6.7–7.7 MeV by the 15 N + α scatteringexperiment,” J. Korean Phys. Soc. 73, 265–270 (2018).
Y. P. Xu, D. Y. Pang, X. Y. Yun, S. Kubono, C. A. Bertulani, C. X. Yuan, “Possible determination of high-lying single-particle components
with (p, d) reactions,” Phys. Rev. C 98, 044622 (2018).
L. Y. Zhang, J. J. He, S. Wanajo, D. Dell’Aquila, S. Kubono, G. Zhao, “New thermonuclear 10 B(α, p)13 C rate and its astrophysicalimplication in the νp-process,” Astrophys. J. 868, 24 (2018).
S. Takeuchi, T. Nakamura, M. Shikata, Y. Togano, Y. Kondo, J. Tsubota, T. Ozaki, A. Saito, H. Otsu, He Wang, H. Sakurai, Y. Watanabe, S. Kawase, D. S. Ahn, M. Aikawa, T. Ando, S. Araki, Sidong Chen, N. Chiga, P. Doornenbal, S. Ebata, N. Fukuda, T. Isobe,
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S. Nagamine, K. Nakano, M. Niikura, K. Ogata, T. Saito, Y. Shiga, Y. Shimizu, S. Shimoura, T. Sumikama, P. A. Söderstrom, H. Suzuki,
H. Takeda, R. Taniuchi,M. Uesaka, Y. Watanabe, K. Wimmer, T. Yamamoto, K. Yoshida, “Coulomb breakup reactions of 93, 94 Zr ininverse kinematics,” Prog. Theor. Exp. Phys. 2019, 013D02 (2019).
Z. Y. Xu, H. Heylen, K. Asahi, F. Boulay, J. M. Daugas, R. P. de Groote, W. Gins, O. Kamalou, Á. Koszorús, M. Lykiardopoulou,
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Y. Ichikawa, Y. Ichikawa, H. Nishibata, A. Takamine, K. Imamura, T. Fujita, T. Sato, Y. Shimizu, D. S. Ahn, K. Asahi, H. Baba,
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[Proceedings]
H. Wang, N. Aoi, S. Takeuchi, M. Matsushita, P. Doornenbal, T. Motobayashi, D. Steppenbeck, K. Yoneda, H. Baba, Zs. Dombrádi,
K. Kobayashi, Y. Kondo, J. Lee, H. Liu, R. Minakata, D. Nishimura, H. Otsu, H. Sakurai, D. Sohler, Y. Sun, Z. Tian, R. Tanaka,
Y. Yogano, Zs. Vajta, Z. Yang, T. Yamamoto, Y. Ye, R. Yokoyama, “Nuclear structure study for the neutron-rich nuclei beyond 132 Sn:
In-beam gamma-ray spectroscopy of 136 Sn and 132 Cd,” EPJ Web Conf. 178, 02019 (2018).
G. X. Zhang, H. Watanabe, F. G. Kondev, G. J. Lane, P. H. Regan, P.-A. Söderström, P. M. Walker, 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, R. J. Carroll, K. Y. Chae, 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, C. S. Lee, E. J. Lee, G. Lorusso, G. Lotay, C.-B Moon, I. Nishizuka, C. R. Nita, A. Odahara, Z. Patel,
V. H. Phong, Zs. Podolyák, O. J. Roberts, H. Sakurai, H. Schaﬀner, C. M. Shand, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda,
S. Terashima, Zs. Vajta, J. J. Valiente-Dóbon, Z. Y. Xu, “β-γ and isomeric decay spectroscopy of 168 Dy,” EPJ Web Conf. 178, 02023(2018).
X. Sun, H. Wang, H. Otsu, H. Sakurai, D. S. 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. Söderström, H. Suzuki,“Reaction study of 136 Xe on proton, deuteron and carbon at 168 A MeV,” Proceedings of the 15th International Conference on Nuclear
Reaction Mechanisms, edited by F. Cerutti, A. Ferrari, T. Kawano, F. Salva-Pujol, P. Talou, CERN-Proceedings-2019-001, 153–157- 263 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(CERN, Geneva, 2019).
T. Yamamoto, H. M. Shimizu, M. Kitaguchi, K. Hirota, T. Okudaira, C. C. Haddock, N. Oi, I. Ito, S. Endo, S. Takada, J. Koga, T. Yoshioka,
T. Ino, K. Asahi, T. Momose, T. Iwata, K. Sakai, T. Oku, A. Kimura, M. Hino, T. Shima, Y. Yamagata, “Development of a neutron spin
filter for a T violation search in compound nuclei,” JPS Conf. Proc. 22, 011018 (2018).
M. Kitaguchi, K. Asahi, S. Endo, Christopher C. Haddock, M. Hino, K. Hirota, T. Ino, I. Ito, T. Iwata, J. Koga, Y. Miyachi, T. Momose,N. Oi, T. Okudaira, K. Sakai, T. Shima, H. M. Shimizu, S. Takada, Y. Yamagata, T. Yamamoto, T. Yoshioka, “Fundamental physics
using high-performance optics,” JPS Conf. Proc. 22, 011034 (2018).
J. Koga, S. Takada, T. Yoshioka, H. M. Shimizu, K. Hirota, T. Okudaira, N. Oi, I. Ito, T. Yamamoto, S. Endo, C. C. Haddock, M. Kitaguchi,
A. Kimura, K. Sakai, T. Ino, K. Asahi, T. Momose, T. Iwata, M. Hino, T. Shima, Y. Yamagata, “Measurement of (n, γ) reaction of 117 Sn
for T -violation search by using compound nucleus,” JPS Conf. Proc. 22, 011035 (2018).
T. Okudaira, H. M. Shimizu, M. Kitaguchi, K. Hirota, C. C. Haddock, N. Oi, I. Ito, T. Yamamoto, S. Endo, S. Takada, J. Koga, T. Yoshioka,
T. Ino, K. Asahi, T. Momose, T. Iwata, K. Sakai, T. Oku, A. Kimura, M. Hino, T. Shima, Y. Yamagata, “Measurement of angular
distributions in 139 La(n, γ) reaction for T violation search,” JPS Conf. Proc. 22, 011041 (2018).

[Others]தҪཅҰ, ʮେ‫ؾ‬ඍཻࢠͱۜՏӉ஦ઢʯ, Ճ଎‫ث‬ϋϯυϒοΫୈ 20.3.2 અ, 2018 ೥, ‫ؙ‬ળग़൛.
੢ଜढ़ೋ, ʮ์ࣹੑ֩छͷ୹ण໋൒‫ظݮ‬ଌఆ—ΤΩινοΫͳෆ҆ఆ֩ͷ่յͱ‫ݩ‬ૉ߹੒—ʯ, ‫ֶྗࢠݪ‬ձࢽ ATOMOΣ 60, No. 10,
35–39 (2018).
খᖛ༸ԝ, ʮ͘Ζͨ·໛‫ ܕ‬in PHITSʯ, ʰ֩σʔλχϡʔεʱ, No.122 (௨‫ ר‬158 ߸), p. 44, 2019 ೥ 2 ݄.
ࢁத௕ؓ, ٢Ӭঘ޹, ѴߞҰ࿠, ʮ൓࣓ੑ‫ࢠݪ‬ͷి‫ؾ‬૒‫ࢠۃ‬ϞʔϝϯτͰ୳Δ৽෺ཧʯ, ೔ຊ෺ཧֶձࢽ 73, 382–387 (2018).

Oral Presentations[International Conference etc.]
H. Sakurai (invited), “Facility-upgrade of RIBF for diversity enhancement in nuclear physics,” 13th International Conference on NucleusNucleus Collisions NN2018, Omiya, Japan, December 4–8, 2018.
H. Sakurai (invited), “Recent highlights and future programs at RIBF,” The 10th China-Japan Joint Nuclear Physics Symposium, Huizhou,
China, November, 2018.
H. Sakurai (invited), “Recent activities and highlights at the RIBF,” International Conference on Simplicity, Symmetry and Beauty ofAtomic Nuclei, Shanghai, China, September, 2018.
H. Sakurai (invited), “The RIBF Facility and Its Future,” 20th Northeastern Asian Symposiu-2018 on Nuclear Physics in the 21st Century,
Nagoya, September, 2018.
H. Sakurai (invited), “Recent activities and perspectives,” 1st Symposium on Intermediate-energy Heavy Ion Collisions (iHIC2018),
Beijing, China, April, 2018.
S. Nishimura (invited), “Experimental challenges relevant to the r-process,” EMMI Rapid Reaction Task Force: The physics of neutronstar mergers at GSI/FAIR Symposium GSI, Darmstadt, Germany, June 4–15, 2018.
S. Nishimura (invited), “Decay spectroscopy of exotic nuclei at RIBF,” International workshop on Physics at HIAF High-Energy BeamLines and Nuclear Astrophysics, Beihang Univ., China, December 13–15, 2018.
S. Nishimura (invited), “Experiments Relevant to r-Process Nucleosynthesis at RIBF,” 5th Joint Meeting of the APS Division of Nuclear
Physics and the Physical Society of Japan, Hawaii, USA, October 23, 2018.
S. Nishimura (invited), “Experiments related to r-process nucleosynthesis at RIBF,” Nuclear Physics in Stellar Explosions, Debrecen,
Hungary, September 12–14, 2018.
S. Nishimura (invited), “Experiments related to astrophysical nucleosynthesis,” 20th Northeastern Asian Symposiu-2018 on Nuclear
Physics in the 21st Century, Nagoya, September, 2018.
T. Isobe (invited), “The SπRIT and pion detectors in RIKEN for the experimental study of symmetry energy with heavy ion collisions,”
International Workshop on Multi facets of Eos and Clustering, Catania, Italy, May 22–25, 2018.
T. Isobe (invited), “Implementation of GET readout system for heavy RI collision experiment with SπRIT-TPC at RIBF,” GET Workshop:
General Electronic for Physics, Haut Carre, France, October 10–12, 2018.
T. Isobe (invited), “Study of density dependent asymmetric nuclear EOS by using heavy RI collisions at RIKEN-RIBF,” 52nd Reimei
Workshop “Experimental and Theoretical Hadron Physics: Recent Exciting Developments,” Tokai, Japan, January 9–11, 2019.
T. Isobe (invited), “Experimental study of density dependent symmetry energy at RIBF-SπRIT experiment,” 5th Joint Meeting of the APS
Division of Nuclear Physics and the Physical Society of Japan, Hawaii, USA, October 23–27, 2018.
P. Doornenbal (invited), “Spectroscopy of neutron-rich Ca and Ni isotopes,” Nuclear Structure 2018 (NS2018), East Lansing, USA,
August 6–10, 2018.
D. Suzuki (invited), “Transfer reaction experiments using deuterated isobutene gas in active targets,” Workshop on Gas-filled Detectors
and Systems (GDS): Rare-gas target handling and recycling systems, Institute de Physique Nucléaire d’Orsay, France, January 23–25,
2019.
S. Kubono (invited), “Possible programs at HUS pelletron in nuclear astrophysics—Approach to core-collapse supernovae—,” International Workshop on research opportunity at HUS Pelletron Facility, Hanoi University of Science, Hanoi, Vietnam, April 12, 2018.
S. Kubono (invited), “Experimental challenge to the cosmological Li problem,” Int. Conf. on Nuclei in the Cosmos (NIC 2018), Gran
Sasso, Italy, June 25–29, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

S. Kubono (invited), “Heavy element synthesis under explosive burning on neutron stars,” ASRC International Workshop, Tokai, Japan,
March 25–27, 2019.
H. Wang et al., “Nuclear reaction study for long-lived fission products in high-level radioactive waste: Cross section measurements for
proton- and deuteron-induced spallation reactions,” 13th International Conference on Nucleus-Nucleus Collisions (NN2018), Omiya,
Saitama, Japan, December 4–8, 2018.
H. Wang et al., “Spallation reaction study for fission products in nuclear waste: Cross section measurements for 107 Pd, 137 Cs, 136 Xe, and90
Sr on proton and deuteron at diﬀerent reaction energies,” Fifteenth NEA Information Exchange Meeting on Actinide and Fission
Product Partitioning and Transmutation, Manchester Hall, Manchester, UK, September 30–October 3, 2018.
H. Wang et al., “Nuclear reaction study for high-level radioactive waste: Cross section measurements for proton- and deuteron-induced
spallation reactions of long-lived fission products,” The 15th edition of the Varenna Conference on Nuclear Reaction Mechanisms(NRM), Varenna, Italy, June 11–15, 2018.
H. Wang et al., “Nuclear structure study for the neutron-rich cadmium nuclei beyond 132 Sn,” The 10th international conference on Direct
Reactions with Exotic Beams (DREB2018), Matsue, Japan, June 5–8, 2018.
M. L. Cortes (invited), “Development of a new scintillation detector based spectrometer at the RIBF,” 3rd Workshop of the Nuclear
Spectroscopy Instrumentation Network of ENSAR2 (NuSpIn), Valencia, Spain, June 25–29, 2018.
M. L. Cortes (invited), “Recent results from in-beam gamma experiments at the RIBF,” NUSTAR Annual meeting 2019, GSI, Darmstadt,
Germany, February 25–March 1, 2019.
M. L. Cortes et al., “First Spectroscopy of 62 Ti: Shell Evolution Towards 60 Ca,” Nuclear Structure 2018 (NS2018), East Lansing, USA,
August 5–10, 2018.
M. Kurata-Nishimura et al., “Collective flow at neutron rich Sn+Sn collisions with 270 MeV/u,” 8th International Symposium on Nuclear
Symmetry Energy (NuSYM2018), Busan, South Korea, September 10–13, 2018.
M. Kurata-Nishimura et al., “Collective flow at neutron rich Sn+Sn collisions with 270 MeV/u,” 13th International Conference on
Nucleus-Nucleus Collisions NN2018, Omiya, Japan, December 4–8, 2018.
M. Kurata-Nishimura et al., “SπRIT-TPC experiment with neutron rich Sn + Sn collisions in RIKEN-RIBF,” 5th Joint Meeting of the
APS Division of Nuclear Physics and the Physical Society of Japan, Hawaii, USA, October 23–27, 2018.
M. Kaneko et al., “Study of light cluster production in intermediate energetic heavy-RI collision at RIBF,” 13th International Conferenceon Nucleus-Nucleus Collisions NN2018, Omiya, Japan, December 4–8, 2018.
M. Kaneko et al., “Study of light cluster production in intermediate energetic heavy-RI collision at RIBF,” 8th International Symposium
on Nuclear Symmetry Energy (NuSYM2018), Busan, South Korea, September 10–13, 2018.
M. Kaneko et al., “Study of light cluster production in intermediate energetic heavy-RI collision at RIBF,” 5th Joint Meeting of the APS
Division of Nuclear Physics and the Physical Society of Japan, Hawaii, USA, October 23–27, 2018.
X. Sun et al., “Reaction study of 136 Xe on proton, deuteron and carbon at 168 MeV/u,” 15th Varenna Conference on Nuclear Reaction
Mechanism, Varenna, Italy, June 11–15, 2018.

[Domestic Conference]ᓎҪതّʢট଴ߨԋʣ, ʮ‫ݩ‬ૉͷਐԽ, ߹੒ͱม‫׵‬ʯ, ֶज़ձٞ ެ։γϯϙδ΢Ϝ, ʮ‫ૅج‬Պֶ‫ڀݚ‬ͷҙٛͱࣾձʢ෺ཧ෼໺͔Βʣʯ,౦‫ژ‬, 2018 ೥ 12 ݄ 17 ೔.
ᓎҪതّʢট଴ߨԋʣ, ʮ‫ݩ‬ૉม‫׵‬ͷ‫ͱڀݚૅج‬কདྷʯ, ֶज़ձٞ ެ։γϯϙδ΢Ϝ, ʮૉཻࢠ෺ཧɾ‫֩ࢠݪ‬෺ཧ෼໺ͷେ‫ࢪܕ‬ઃ‫ܭ‬ըɾେ‫ن‬໛‫ܭڀݚ‬ըϚελʔϓϥϯʯ, ౦‫ژ‬, 2019 ೥ 2 ݄ 19 ೔.
੢ଜढ़ೋʢট଴ߨԋʣ, ʮZDS ʹ͓͚Δॏ‫ݩ‬ૉ߹੒ʯ, ‫ڀݚ‬ձ, ʮॏྗ͸‫؍‬ଌ࣌୅ͷ́ϓϩηεͱෆ҆ఆ֩ʯ, ཧ‫ݚ‬, 2018 ೥ 6 ݄ 20–22
೔ʢ20 ೔ʣ.
S. Nishimura (invited), “Study on r-process at RIKEN RIBF,” ೔ຊ෺ཧֶձɿ“Korea-Japan Symposium on Unstable Nuclei and Nuclear
Astrophysics,” ‫۝‬भେֶ, 2019 ೥ 3 ݄ 14 ೔.
੢ଜढ़ೋ ʢট଴ߨԋʣ, ʮ่յ͔Β୳Δॏ‫ݩ‬ૉ߹੒ʯ, ‫ڀݚ‬ձʮ௒ॏ‫ݩ‬ૉ‫ڀݚ‬ͷ৽ల։ʯ, ‫۝‬भେֶ, 2018 ೥ 7 ݄ 30–31 ೔.
੢ଜढ़ೋ ʢট଴ߨԋʣ, ʮCERN-NA44 ࣮‫ݧ‬ʢॳ‫ظ‬ʣʯ, ‫ه‬೦‫ڀݚ‬ձʮ޿ౡେֶʹ͓͚ΔϋυϩϯɾΫΥʔΫ෺ཧֶͷาΈʯ, ޿ౡେֶ, 2019 ೥ 3 ݄ 11 ೔.
ү෦஧ত, ʮཧ‫ ݚ‬RIBF ʹ͓͚Δॏ RI িಥ࣮‫༻ݧ‬λΠϜϓϩδΣΫγϣϯνϟϯόʔͷੑೳධՁʯ, ೔ຊ෺ཧֶձ೥࣍େձ, ෱Ԭ
ࢢ, 2019 ೥ 3 ݄.
෌ా੒෉, ࢁຊ௚थ, தҪཅҰ, ʮ੩ిϦϯάΛ༻͍ͨ Li@C60 + + e− ࣮‫ݧ‬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱Ԭࢢ, 2019 ೥ 3 ݄
15 ೔.
P. Doornenbal (invited), “SUNFLOWER status report,” RIBF UEC Meeting, Wako, Japan, September 5–6, 2018.
D. Suzuki (invited), “Study of rp-process at OEDO,” OEDO workshop, Riken Wako Campus, Japan, June 11, 2018.
H. Wang, “Spallation reaction study for fission products in high-level radioactive waste: Towards a new invention of nuclear transmutation,” the All RIKEN workshop 2018, Wako, Japan, December 14, 2018.
M. L. Cortes, “First spectroscopy of 62 Ti,” RIBF Week 2018, Wako, Japan, September 3–7, 2018.
M. L. Cortes, “Recent developments towards a new scintillator array at RIBF using GAGG detector,” RIBF Week 2018, Wako, Japan,
September 3–7, 2018.
M. L. Cortes, “Fall 2018 beam time overview,” RIBF Week 2018, Wako, Japan, September 3–7, 2018.
F. Browne, “Asymmetric dynamics around the magic octupole numbers Z = 34 and N = 54,” RIBF Week 2018, RIKEN, Wako, Japan,
September 3–7, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Posters Presentations[International Conference etc.]
Y. Nakai, N. Watanabe, Y. Oba, “Laboratory experiment for hydrogenation of C60 fullerenes deposited on a solid surface under low
temperature conditions,” The Olympian Symposium 2018 on “Gas and stars from milli- to mega- parsecs,” Paralia Katerini, May 31,
2018.
X. Sun et al., “Isotopic cross sections of proton-, deuteron- and carbon-induced reactions on 136 Xe,” 13th International Conference on
Nucleus-Nucleus Collisions, Omiya, Japan, December 4–8, 2018.
H. Shimizu et al., “Isomeric RIB Production of Aluminum-26,” XV International Symposium on Nuclei in the Cosmos, Assergi, Italy,
June 24–29, 2018.

[Domestic Conference]தҪཅҰ, ౉෦௚थ, “௿Թബບঢ় C60 ‫ݻ‬ମʹτϥοϓ͞Εͨਫૉ෼ࢠͷৼಈճసྭ‫ى‬ͷ੺֎‫ٵ‬ऩεϖΫτϧ,” ‫ࢠݪ‬িಥֶձୈ 43
ճ೥ձ, Ӊ࣏, 2018 ೥ 10 ݄ 13 ೔.

Seminars/Lectures
S. Nishimura, “Introduction of RIKEN,” “Studying nuclear structure using RI beams,” “Possibility using pelletron for nuclear physics
experiment,” International Training Course on the Possibilities for Studying Nuclear Physics using the Pelletron Accelerator, Hanoi,
Vietnam, December 17–20, 2018.
H. Wang, “Reaction study for fission products in high-level radioactive waste for nuclear transmutation,” The 411th PKU Lecture on
Nuclear Science, Peking University, Beijing, China, January 9, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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
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(02 + ))are being used to search for double Gamow-Teller resonances.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(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:(1) Polarized proton target (described in (4))(2) Thin solid hydrogen target(3) MINOS (developed at Saclay and hosted by the Spin Isospin Laboratory)

Members
Group Director
Tomohiro UESAKA
Research/Technical Scientists
Masaki SASANO (Research Scientist)
Juzo ZENIHIRO (Research Scientist)

Sarah NAIMI (Research Scientist)
Kenichiro YONEDAYONEDA (Senior Research Scientist)

Contract Researchers
Daisuke NAGAE
Takeshi INOUE

Kenichiro TATEISHI

Special Postdoctoral Researchers
Kenichiro TATEISHI

Yuki KUBOTA

Postdoctoral Researchers
Fumi SUZAKI

Takahiro NISHI

Research Associate
Masami SAKO
Junior Research Associates
Shunichiro OMIKA (Saitama Univ.)
Shoichiro MASUOKA (Univ. of Tokyo)

Shusuke TAKADA (Kyushu Univ.)

International Program Associates
Jian GAO (Peking Univ.)
Siwei HUANG (Peking Univ.)
Jian GAO (Peking Univ.)

Siwei HUANG (Peking Univ.)
Hongfu LI (Institute of Modern Physics, Chinese Academic of
Science)

Short International Program Associate
Dana TUDOR (Univ. of Bucharest)
Research Consultants
Harutaka SAKAGUCHI

Kazuko TANABE- 268 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Senior Visiting Scientist
Hiroyuki SAGAWA (Aizu Univ.)
Visiting Scientists
Didier BEAUMEL (IPN)
Panin VALELII (CEA Saclay)
Yasuyuki SUZUKI (Niigata Univ.)
Yang ZAIHONG (Osaka Univ.)
Yosuke KONDO (Tokyo Tech.)Junki TANAKA (TU darmstadt.)
Zoltan ELEKES (ATOMKI)
Dorottya KUNNE SOHLER (Institute of Nuclear Research
Hungarian Academy of Sciences (ATOMKI))
Hidetoshi AKIMUNE (Konan Univ.)
Yohei MATSUDA (Osaka Univ.)
Satoru TERASHIMA (Beihang University)
Yasuhiro TOGANO (Tokyo Tech.)Valdir GUIMARAES (Instituto de Fisica da Universidade de
Sao Paulo)
Satoshi SAKAGUCHI (Kyusyu Univ.)
Kenjiro MIKI (TU Darmstadt)
Yasutaka TANIGUCHI (Nihon Institute of Medical Science)
Valerie LAPOUX (CEA Saclay)
Tetsuaki MORIGUCHI (Univ. of Tsukuba)
Alexandre OBERTELLI (CEA Saclay)
Kazuyuki OGATA (Osaka Univ.)
Alain GILLIBERT (CEA Saclay)
Shinji SUZUKI (Univ. of Tsukuba)
Emanuel POLLACCO (CEA Saclay)
Zsolt VAJTA (Institute of Nuclear Research Hungarian
Academy of Sciences (ATOMKI))
Anna CORSI (CEA Saclay)
Yuma KIKUCHI (Osaka City Univ.)
Istvan KUTI (Institute of Nuclear Research Hungarian
Academy of Sciences (ATOMKI))

Yury LITVINOV (GSI)
Yuhu ZHANG (CAS)
Makoto NEGORO (Osaka Univ.)
Igor GASPARIC (Ruder Boskovic Inst. Zagreb Croatia)
Konstanze BORETZKY (GSI)
Hans Toshihide TOERNQVIST (TU Darmstadt)
Zsolt FULOP (Institute of Nuclear Research Hungarian
Academy of Sciences (ATOMKI))
Christoph CAESAR (GSI)
Haik SIMON (GSI)
Zsolt DOMBRADI (Institute of Nuclear Research Hungarian
MatthiasHOLL(TU Darmstadt)
Academyof Sciences(ATOMKI))
AcademyHOLL
of Sciences(ATOMKI))
Matthias(TU Darmstadt)
Takayuki YAMAGUCHI (Saitama Univ.)
Akinori KAGAWA (Osaka Univ.)
Takashi NAKAMURA (Tokyo Tech.)
Baohua SUN (Beihang Univ.)
Atsushi TAMII (Osaka Univ.)
Leyla ATAR (TU Darmstadt)
Attila KRASZNAHORKAY (ATOMKI)
Zoltan HALASZ (ATOMKI)
Takashi WAKUI (Tohoku Univ.)
Li-Gang CAO (North China Electric Power Univ.)
Kimiko SEKIGUCHI (Tohoku Univ.)
Kaori KAKI (Shizuoka Univ.)
Wang HE (Tokyo Tech.)Zhuang GE (Institute of Modern Physics Chinese Academy of
Sciences)
Momo MUKAI (Tsukuba Univ.)
Yelei SUN (CEA Saclay)

Visiting Technicians
Gilles AUTHELET (CEA Saclay)
Alain DELBART (CEA Saclay)
Jean-Marc GHELLER (CEA Saclay)
Arnaud GIGANON (CEA Saclay)
Cedric PERON (CEA Saclay)

Daniel KOERPER (GSI)
Jean-Yves ROUSSE (CEA Saclay)
Clement HILAIRE (CEA Saclay)
Denis CALVET (CEA Saclay)

Student Trainees
Tatsuya FURUNO (Kyoto Univ.)
Takuma NISHIMURA (Saitama Univ.)
Mizuki SHIKATA (Tokyo Tech.)
Motoki MURATA (Kyoto Univ.)
Junichi TSUBOTA (Tokyo Tech.)Sebastian Benedikt REICHERT (TU Munchen)
Yuuki TAKEUCHI (Saitama Univ.)
Atsumi SAITO (Tokyo Tech.)Syunichirou OHMIKA (Saitama Univ.)
Atomu WATANABE (Tohoku Univ.)
Hiroshi MIURA (Saitama Univ.)
Julian KAHLBOW (TU Darmstadt)
Taras LOKOTKO (Univ. of Hong Kong)
Vadim WAGNER (TU Darmstadt)
Dahee KIM (Ewha Womans Univ.)
Tetsuro SHIMADA (Tokyo Tech.)Tomoyuki MUKAI (Tohoku Univ.)
Hareru MIKI (Tokyo Tech)
Shinnosuke NAKAI (Tohoku Univ.)
Kohei SHIMATANI (Tohoku Univ.)
Takato TOMAI (Tokyo Tech.)Su-yeon PARK (Ewha Womans Univ.)

Akihiro HIRAYAMA (Tokyo Tech.)
Takaaki KOBAYASHI (Saitama Univ.)
Simon LINDBERG (Chalmers University of Technology)
Masanori HOSOYAMADA (Kyushu Univ.)
Masamichi AMANO (Univ. of Tsukuba)
Yusuke KAWASHIMA (Kyushu Univ.)
Daisuke SAKAE (Kyushu Univ.)
Saiya FUJIWARA (Kyushu Univ.)
Kiyoshi WAKAYAMA (Saitama Univ.)
Mamoru SAKAUE (Saitama Univ.)
Sergey CHEBOTARYOV (Kyungpook National Univ.)
Kenjiro YOKOTA (Saitama Univ.)
Alexandra-Ionela CHILUG (Univ. of Bucharest)
Shun HOSOI (Saitama Univ.)
Tomoya HARADA (Toho Univ.)
Yasuhito INADA (Saitama Univ.)
Kosei TANIUE (Univ. of Miyazaki)
Li PENJIE (The Univ. of Hong Kong)
Masahiro YASUDA (Tokyo Tech.)
Shuhei GOTO (Kyushu Univ.)
YAMADA (Tokyo
Hiroki YAMADA(TokyoTech)
Tech.)
Jianwei ZHAO (Beihang Univ.)- 269 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Leo KAGESAWA (Tsukuba Univ.)
Hiroki ARAKAWA (Saitama Univ.)
Daiki HAMAKAWA (Saitama Univ.)
Kento INABA (Kyoto Univ.)
Yu Takahashi(KyotoUniv.)Univ.)
Yu
TAKAHASHI(KyotoWenbo DOU (Saitama Univ.)
Toshiya KAWAMURA (Toho Univ.)
Daisuke KAJIKI (Saitama Univ.)
Midori MIWA (Saitama Univ.)
Yuta UTSUGI (Tohoku Univ.)
Evgeniy MILMAN (Kyungpook National Univ.)
Minami INOUE (Tohoku Univ.)Nancy Anne HUPIN (University of Paris-Saclay)
Yuya HAMANO (Kyushu Univ.)
Yang LIU (Peking Univ.)
Shigehito SAKAKI (Kyushu Univ.)
Jun FENG (Peking Univ.)
Taishi KUBO (Kyushu Univ.)
Biao YANG (Peking Univ.)
Riku MATSUMURA (Toho Univ.)
Zanetti LORENZO (TU Darmstadt)

Jun OKAMOTO (Tohoku Univ.)
Hisanori Oshiro(Kyushu
Univ.)OSHIRO(Kyushu
Univ.)
Yu NASU (Tohoku Univ.)
Daiki INOMOTO (Kyushu Univ.)
Shota MATSUMOTO (Kyoto Univ.)
Shunya ISHIDA (Tohoku Univ.)
Simon GIRAUD (Université de Nantes)
Yuma HIRAI (Kyushu Univ.)
Yu ANDO (Kyungpook National Univ.)
Dora SZALKAI (Eotvos Larand Univ.)
Mayuko MATSUMOTO (Tokyo Tech.)Shinji MITSUMOTO (Kyushu Univ.)
Daiki KAMIOKA (Univ. of Tsukuba)
Hina KASAHARA (Kyushu Univ.)
Christopher LEHR (TU Darmstadt)
Akira YASUDA (Tokyo Tech.)Tomoya FUJII (Saitama Univ.)
Yuuki FUJII
Yuuki
FUJII (Tokyo(Tokyo Tech)
Tech.)
Kunimitsu NISHIMURO (Saitama Univ.)
Yuuki YOSHITOME (Tokyo Tech.)
Kumi INOMATA (Saitama Univ.)
InternRichard CRANE
Part-time Worker
Kotaro YAMADA
Assistants
Emiko ISOGAI

Yuri TSUBURAI

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
S. Adachi, T. Kawabata, K. Minomo, T. Kadoya, N. Yokota, H. Akimune, T. Baba, H. Fujimura, M. Fujiwara, Y. Funaki, T. Furuno,
T. Hashimoto, K. Hatanaka, K. Inaba, Y. Ishii, M. Itoh, C. Iwamoto, K. Kawase, Y. Maeda, H. Matsubara, Y. Matsuda, H. Matsuno,
T. Morimoto, H. Morita, M. Murata, T. Nanamura, I. Ou, S. Sakaguchi, Y. Sasamoto, R. Sawada, Y. Shimizu, K. Suda, A. Tamii,
Y. Tameshige, M. Tsumura, M. Uchida, T. Uesaka, H. P. Yoshida, S. Yoshida, “Systematic analysis of inelastic α scattering oﬀ selfconjugate A = 4n nuclei,” Phys. Rev. C 97, 014601 (2018).
S. Chebotaryov, S. Sakaguchi, T. Uesaka, T. Akieda, Y. Ando, M. Assie, D. Beaumel, N. Chiga, M. Dozono, A. Galindo-Uribarri,
B. Heﬀron, A. Hirayama, T. Isobe, K. Kaki, S. Kawase, W. Kim, T. Kobayashi, H. Kon, Y. Kondo, Y. Kubota, S. Leblond, H. Lee,
T. Lokotko, Y. Maeda, Y. Matsuda, K. Miki, E. Milman, T. Motobayashi, T. Mukai, S. Nakai, T. Nakamura, A. Ni, T. Noro, S. Ota,
H. Otsu, T. Ozaki, V. Panin, S. Park, A. Saito, H. Sakai, M. Sasano, H. Sato, K. Sekiguchi, Y. Shimizu, I. Stefan, L. Stuhl, M. Takaki,
K. Taniue, K. Tateishi, S. Terashima, Y. Togano, T. Tomai, Y. Wada, T. Wakasa, T. Wakui, A. Watanabe, H. Yamada, Z. Yang,
M. Yasuda, J. Yasuda, K. Yoneda, J. Zenihiro, “Proton elastic scattering at 200 A MeV and high momentum transfers of 1.7–2.7 fm−1
as a probe of the nuclear matter density of 6 He,” Prog. Theor. Exp. Phys. 2018, 053D01 (2018).
A. Corsi, A. Obertelli, P. Doornenbal, F. Nowacki, H. Sagawa, Y. Tanimura, N. Aoi, H. Baba, P. Bednarczyk, S. Boissinot, M. Ciemala,A. Gillibert, T. Isobe, A. Jungclaus, V. Lapoux, J. Lee, K. Matsui, M. Matsushita, T. Motobayashi, D. Nishimura, S. Ota, E. Pollacco,
H. Sakurai, C. Santamaria, Y. Shiga, D. Sohler, D. Steppenbeck, S. Takeuchi, R. Taniuchi, H. Wang, “Spectroscopy of nuclei around100
Sn populated via two-neutron knockout reactions,” Phys. Rev. C 97, 044321 (2018).
M. L. Cortés, P. Doornenbal, M. Dupuis, S. M. Lenzi, F. Nowacki, A. Obertelli, S. Péru, N. Pietralla, V. Werner, K. Wimmer, G. Authelet,
H. Baba, D. Calvet, F. Château, A. Corsi, A. Delbart, J. M. Gheller, A. Gillibert, T. Isobe, V. Lapoux, C. Louchart, 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, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, 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, R. Lozeva, K. Matsui, T. Miyazaki, S. Nishimura, L. Olivier, S. Ota, Z. Patel, E. Sahin, C. M. Shand, P. A. Söderström, I. Stefan, D. Steppenbeck,
T. Sumikama, D. Suzuki, Z. Vajta, J. Wu, Z. Xu, “Inelastic scattering of neutron-rich Ni and Zn isotopes oﬀ a proton target,” Phys. Rev.
C 97, 44315 (2018).
C. Y. Fu, Y. H. Zhang, X. H. Zhou, M. Wang, Y. A. Litvinov, K. Blaum, H. S. Xu, X. Xu, P. Shuai, Y. H. Lam, R. J. Chen, X. L. Yan,
T. Bao, X. C. Chen, H. Chen, J. J. He, S. Kubono, D. W. Liu, R. S. Mao, X. W. Ma, M. Z. Sun, X. L. Tu, Y. M. Xing, P. Zhang, Q. Zeng,
X. Zhou, W. L. Zhan, S. Litvinov, G. Audi, T. Uesaka, Y. Yamaguchi, T. Yamaguchi, A. Ozawa, B. H. Sun, Y. Sun, F. R. Xu, “Massesof the T z = 3/2 nuclei 27 P and 29 S,” Phys. Rev. C 98, 014315 (2018).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

E. Ha, M. K. Cheoun, H. Sagawa, “Spin singlet and spin triplet pairing correlations on shape evolution in sd-shell N = Z nuclei,” Phys.
Rev. C 97, 24320 (2018).
E. Ha, M. K. Cheoun, H. Sagawa, W. Y. So, “Neutron-proton pairing correlations and deformation for N = Z nuclei in the pf shell within
the deformed BCS and Hartree-Fock-Bogoliubov approach,” Phys. Rev. C 97, 64322 (2018).
S. Kawase, T. Uesaka, T. L. Tang, D. Beaumel, M. Dozono, T. Fukunaga, T. Fujii, N. Fukuda, A. Galindo-Uribarri, S. Hwang, N. Inabe,
T. Kawabata, T. Kawahara, W. Kim, K. Kisamori, M. Kobayashi, T. Kubo, Y. Kubota, K. Kusaka, C. Lee, Y. Maeda, H. Matsubara,
S. Michimasa, H. Miya, T. Noro, Y. Nozawa, A. Obertelli, K. Ogata, S. Ota, E. Padilla-Rodal, S. Sakaguchi, H. Sakai, M. Sasano,S. Shimoura, S. Stepanyan, H. Suzuki, T. Suzuki, M. Takaki, H. Takeda, A. Tamii, H. Tokieda, T. Wakasa, T. Wakui, K. Yako,J. Yasuda, Y. Yanagisawa, R. Yokoyama, K. Yoshida, K. Yoshida, J. Zenihiro, “Exclusive quasi-free proton knockout from oxygenisotopes at intermediate energies,” Prog. Theor. Exp. Phys. 2018, 021D01 (2018).
H. Z. Liang, H. Sagawa, M. Sasano, T. Suzuki, M. Honma, “Gamow-Teller transitions from high-spin isomers in N = Z nuclei,” Phys.
Rev. C 98, 14311 (2018).
X. Y. Liu, Z. Liu, B. Ding, P. Doornenbal, A. Obertelli, S. M. Lenzi, P. M. Walker, L. X. Chung, B. D. Linh, 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, M. Niikura, F. Nowacki, H. Otsu, C. Péron, A. Peyaud, E. C. Pollacco, J. Y. Roussé, H. Sakurai, M. Sasano, Y. Shiga,
S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, Y. H. Lam, T. H. Huang, M. D. Sun, W. Q. Zhang, H. Y. Lu, D. S. 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. A. Söderström, G. L. Stefan, D. Steppenbeck, T. Sumikama, D. Suzuki, Z. Vajta, V. Werner, J. Wu, Z. Xu, X. H. Zhou,
Y. H. Zhang, H. S. Xu, F. S. Zhang, “Spectroscopy of 65, 67 Mn: Strong coupling in the N = 40 island of inversion,” Phys. Lett. B 784,
392 (2018).
A. M. Long, T. Adachi, M. Beard, G. P. A. Berg, M. Couder, R. J. DeBoer, M. Dozono, J. Görres, H. Fujita, Y. Fujita, K. Hatanaka,
D. Ishikawa, T. Kubo, H. Matsubara, Y. Namiki, S. O’Brien, Y. Ohkuma, H. Okamura, H. J. Ong, D. Patel, Y. Sakemi, Y. Shimbara,
S. Suzuki, R. Talwar, A. Tamii, A. Volya, T. Wakasa, R. Watanabe, M. Wiescher, R. Yamada, J. Zenihiro, “α-unbound levels in 34 Ar
from 36 Ar(p, t)34 Ar reaction measurements and implications for the astrophysical 30 S(α, p)33 Cl reaction rate,” Phys. Rev. C 97, 054613(2018).
Z. -J. Luo, K. Yu, X. -R. Zhou, J. -W. Cui, H. Sagawa, “Eﬀects of deformation, pairing and tensor correlation on the evolution of bubble
structure within the Skyrme-Hartree-Fock method,” Eur. Phys. J. A 54, 193 (2018).
S. Michimasa, M. Kobayashi, Y. Kiyokawa, S. Ota, D. S. Ahn, H. Baba, G. P. A. Berg, M. Dozono, N. Fukuda, T. Furuno, E. Ideguchi,
N. Inabe, T. Kawabata, S. Kawase, K. Kisamori, K. Kobayashi, T. Kubo, Y. Kubota, C. S. Lee, M. Matsushita, H. Miya, A. Mizukami,
H. Nagakura, D. Nishimura, H. Oikawa, H. Sakai, Y. Shimizu, A. Stolz, H. Suzuki, M. Takaki, H. Takeda, S. Takeuchi, H. Tokieda,
T. Uesaka, K. Yako, Y. Yamaguchi, Y. Yanagisawa, R. Yokoyama, K. Yoshida, S. Shimoura, “Magic nature of neutrons in 54 Ca: First
mass measurements of 55–57 Ca,” Phys. Rev. Lett. 121, 022506 (2018).
T. Nishi, K. Itahashi, G. P. A. Berg, H. Fujioka, N. Fukuda, N. Fukunishi, H. Geissel, R. S. Hayano, S. Hirenzaki, K. Ichikawa, N. Ikeno,
N. Inabe, S. Itoh, M. Iwasaki, D. Kameda, S. Kawase, T. Kubo, K. Kusaka, H. Matsubara, S. Michimasa, K. Miki, G. Mishima,
H. Miya, H. Nagahiro, M. Nakamura, S. Noji, K. Okochi, S. Ota, N. Sakamoto, K. Suzuki, H. Takeda, Y. K. Tanaka, K. Todoroki,
K. Tsukada, T. Uesaka, Y. N. Watanabe, H. Weick, H. Yamakami, K. Yoshida, “Spectroscopy of pionic atoms in 122 Sn(d, 3 He) reaction
and angular dependence of the formation cross sections,” Phys. Rev. Lett. 120, 152505 (2018).
S. Noji, H. Sakai, N. Aoi, H. Baba, G. P. A. Berg, P. Doornenbal, M. Dozono, N. Fukuda, N. Inabe, D. Kameda, T. Kawabata, S. Kawase,
Y. Kikuchi, K. Kisamori, T. Kubo, Y. Maeda, H. Matsubara, S. Michimasa, K. Miki, H. Miya, H. Miyasako, S. Sakaguchi, Y. Sasamoto,S. Shimoura, M. Takaki, H. Takeda, S. Takeuchi, H. Tokieda, T. Ohnishi, S. Ota, T. Uesaka, H. Wang, K. Yako, Y. Yanagisawa,
N. Yokota, K. Yoshida, R. G. T. Zegers, “Excitation of the isovector spin monopole resonance via the exothermic 90 Zr(12 N, 12 C)
reaction at 175 MeV/nucleon,” Phys. Rev. Lett. 120, 172501 (2018).
X. Roca-Maza, G. Colò, H. Sagawa, “Nuclear symmetry energy and the breaking of the isospin symmetry: How do they reconcile witheach other?,” Phys. Rev. Lett. 120, 01002 (2018).
H. Sagawa, T. Suzuki, “Isoscalar and isovector spin response in sd-shell nuclei,” Phys. Rev. C 97, 054333 (2018).
C. Santamaria, A. Obertelli, S. Ota, M. Sasano, E. Takada, L. Audirac, H. Baba, D. Calvet, F. Château, A. Corsi, A. Delbart, P. Doornenbal,
A. Giganon, A. Gillibert, Y. Kondo, Y. Kubota, C. Lahonde-Hamdoun, V. Lapoux, D. Leboeuf, C. S. Lee, H. N. Liu, M. Matsushita,
T. Motobayashi, M. Niikura, M. Kurata-Nishimura, H. Otsu, A. Peyaud, E. C. Pollacco, G. Prono, H. Tokieda, T. Uesaka, J. Zenihiro,“Tracking with the MINOS Time Projection Chamber,” Nucl. Instrum. Methods Phys. Res. A 905, 138 (2018).
Z. Vajta, D. Sohler, Y. Shiga, K. Yoneda, K. Sieja, D. Steppenbeck, Z. Dombrádi, N. Aoi, P. Doornenbal, J. Lee, H. Liu, M. Matsushita,
S. Takeuchi, H. Wang, H. Baba, P. Bednarczyk, Z. Fülöp, S. Go, T. Hashimoto, E. Ideguchi, K. Ieki, K. Kobayashi, Y. Kondo,
R. Minakata, T. Motobayashi, D. Nishimura, H. Otsu, H. Sakurai, Y. Sun, A. Tamaii, R. Tanaka, Z. Tian, T. Yamamoto, X. Yang,
Z. Yang, Y. Ye, R. Yokoyama, J. Zenihiro, “Proton single particle energies next to 78 Ni: Spectroscopy of 77 Cu via single proton
knock-out reaction,” Phys. Lett. B 782, 99 (2018).
Y. M. Xing, K. A. Li, Y. H. Zhang, X. H. Zhou, M. Wang, Y. A. Litvinov, K. Blaum, S. Wanajo, S. Kubono, G. Martı́nez-Pinedo,
A. Sieverding, R. J. Chen, P. Shuai, C. Y. Fu, X. L. Yan, W. J. Huang, X. Xu, X. D. Tang, H. S. Xu, T. Bao, X. C. Chen, B. S. Gao,J. J. He, Y. H. Lam, H. F. Li, J. H. Liu, X. W. Ma, R. S. Mao, M. Si, M. Z. Sun, X. L. Tu, Q. Wang, J. C. Yang, Y. J. Yuan, Q. Zeng,
P. Zhang, X. Zhou, W. L. Zhan, S. Litvinov, G. Audi, T. Uesaka, Y. Yamaguchi, T. Yamaguchi, A. Ozawa, C. Fröhlich, T. Rauscher,
F. K. Thielemann, B. H. Sun, Y. Sun, A. C. Dai, F. R. Xu, “Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and theirimpact on rp and νp nucleosynthesis processes,” Phys. Lett. B 781, 358 (2018).
Y. H. Zhang, P. Zhang, X. H. Zhou, M. Wang, Y. A. Litvinov, H. S. Xu, X. Xu, P. Shuai, Y. H. Lam, R. J. Chen, X. L. Yan, T. Bao,
X. C. Chen, H. Chen, C. Y. Fu, J. J. He, S. Kubono, D. W. Liu, R. S. Mao, X. W. Ma, M. Z. Sun, X. L. Tu, Y. M. Xing, Q. Zeng,- 271 -

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X. Zhou, W. L. Zhan, S. Litvinov, K. Blaum, G. Audi, T. Uesaka, Y. Yamaguchi, T. Yamaguchi, A. Ozawa, B. H. Sun, Y. Sun, F. R. Xu,“Isochronous mass measurements of T z = −1 fp-shell nuclei from projectile fragmentation of 58 Ni,” Phys. Rev. C 98, 14319 (2018).

[Proceedings]

V. P. Ladygin, A. V. Averyanov, E. V. Chernykh, D. Enache, Y. V. Gurchin, A. Y. Isupov, M. Janek, J. T. Karachuk, A. N. Khrenov,
D. O. Krivenkov, P. K. Kurilkin, N. B. Ladygina, A. N. Livanov, S. M. Piyadin, S. G. Reznikov, Y. T. Skhomenko, A. A. Terekhin,
A. V. Tishevsky, T. Uesaka, “First results on the energy scan of the vector Ay and tensor Ayy and A xx analyzing powers in deuteron-proton
elastic scattering at nuclotron,” in XVII Work. High Energy Spin Phys. “DSPIN-2017,” 938, 12007 (2018).
M. Lettmann, V. Werner, N. Pietralla, P. Doornenbal, A. Obertelli, T. R. Rodriguez, K. Sieja, G. Authelet, H. Baba, D. Calvet, F. Chateau,
S. Chen, A. Corsi, A. Delbart, J. M. Gheller, A. Giganon, A. Gillibert, V. Lapoux, T. Motobayashi, M. Niikura, N. Paul, J. Y. Roussé,H. Sakurai, C. Santamaria, D. Steppenbeck, R. Taniuchi, T. Uesaka, T. Ando, T. Arici, A. Blazhev, F. Browne, A. Bruce, R. J. Caroll,
L. X. Chung, M. L. Cortés, M. Dewald, B. Ding, F. Flavigny, S. Franchoo, M. Górska, A. Gottardo, A. Jungclaus, J. Lee, B. D. Linh,
J. Liu, Z. Liu, C. Lizarazo, S. Momiyama, K. Moschner, S. Nagamine, N. Nakatsuka, C. Nita, C. R. Nobs, L. Olivier, Z. Patel,
Z. Podolyák, M. Rudigier, T. Saito, C. Shand, P. A. Söderström, I. Stefan, V. Vaquero, K. Wimmer, Z. Xu, “Signatures of triaxiality inlow-spin spectra of 86 Ge,” in XXII Int. Sch. Nucl. Physics, Neutron Phys. Appl. 1023, 12023 (2018).
Y. Niu, G. Colo, E. Vigezzi, C. Bai, Z. Niu, H. Sagawa, “Beyond mean-field description of Gamow-Teller resonances and β-decay,” in12th Int. Spring Semin. Nucl. Phys. Curr. Probl. Prospect. Nucl. Struct. 966, 12046 (2018).
H. Sagawa, K. Hagino, “Di-neutron correlations and decay dynamics of nuclei near and beyond drip line,” in 12th Int. Spring Semin. Nucl.
Phys. Curr. Probl. Prospect. Nucl. Struct. 966, 12003 (2018).

Oral Presentations[International Conference etc.]
T. Uesaka (invited), “Various aspects of nuclear matter studied with direct reactions,” International Workshop on New Aspects of Hadronand Nuclear/Astro Physics, Tashkent, Uzbekistan, November 5–10, 2018.
T. Uesaka (invited), “30-year perspective of experimental nuclear physics at RIBF/RCNP,” International Symposium on the paths ofnuclear physics from 1950’s towards 2020’s, Tokyo, Japan, September 23, 2018.
T. Uesaka (invited), “Congelation of correlated nucleons in nuclei,” 20th Northeastern Asian Symposium-2018 on Nuclear Physics in the
21st Century, Nagoya, Japan, September 19–20, 2018.
T. Uesaka (invited), “Nuclear Doube Gamow-Teller Responses—little known aspects of nuclear structure—,” 6th Symposium on Neutrinos and Dark Matter in Nuclear Physics 2018, Daejeon, Korea, June 29–July 4, 2018.
H. Sagawa, “The nuclear symmetry energy and the breaking of the isospin symmetry: How do they reconcile with each other?,” 13th
International conference on nucleus-nucleus collisions (NN2018), Saitama, Japan, December 4–8, 2018.
H. Sagawa (invited), “Current topics of spin-isospin response,” IVth Topical Workshop on Modern Aspects of in Nuclear Structure,
Bormio, Italy, February 2018.
M. Sasano, “Gamow-Teller Giant Resonance in 132 Sn,” 13th International conference on nucleus-nucleus collisions (NN2018), Saitama,
Japan, December 4–8, 2018.
S. Naimi, “Rare-RI Ring (R3) at RIBF/Riken: Mass measurement of r-process nuclei,” Workshop on Nuclear Astrophysics at Rings andRecoil Separators, GSI Darmstadt, Germany, March 2018.
J. Zenihiro, “Direct determination of neutron skin thickness of 48 Ca via proton elastic scattering,” 13th International conference on
nucleus-nucleus collisions (NN2018), Saitama, Japan, December 4–8, 2018.
J. Zenihiro, “Direct determination of neutron skin thickness of 48 Ca from proton elastic scattering and the ESPRI project,” Hawaii2018-Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and JPS, Hawaii, USA, October 2018.
J. Zenihiro, “New detector design for (p, p), (p, pX) experiments,” SAMURAI Workshop, RIBF week 2018, Saitama, Japan, September
2018.
J. Zenihiro, “Overview of RIBF,” The 17th CNS International Summer School (CNSSS18), Saitama, Japan, August 2018.
Y. Kubota, “Probing neutron-neutron correlation in 11 Li via the quasi-free (p, pn) reaction,” Hadrons and Nuclear Physics meet ultracold
atoms: a French Japanese workshop, Paris, France, January 2018.
K. Tateishi (invited), “Neutron spin filter based on nuclear polarization technique,” Polarised Neutrons for Condensed-Matter Investigations (PNCMI), UK, July 2018.
J. Gao, “Study of Gamow-Teller transition on 14 Be with PANDORA,” 13th International conference on nucleus-nucleus collisions(NN2018), Saitama, Japan, December 4–8, 2018.
M. Miwa, “Production of n-rich nuclei via 2-proton knockout with deuterium target,” 13th International conference on nucleus-nucleus
collisions (NN2018), Saitama, Japan, December 4–8, 2018.

[Domestic Conference]দా༸ฏ, ʮ୸ૉ 14 ภ‫ۃ‬ཅࢠ஄ੑࢄཚଌఆͷ‫ݱ‬ঢ়ʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ, ౦‫ژ‬ཧՊେֶ, ໺ా, 2018 ೥ 3 ݄ 22–25 ೔.
‫ాݪ‬஌໵, ʮେ‫౓ڧ‬ΠΦϯϏʔϜ༻ͷ Xe ΨεγϯνϨʔγϣϯ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ, ౦‫ژ‬ཧՊେֶ, ໺
ా, 2018 ೥ 3 ݄ 22–25 ೔.
দຊᠳଡ, ʮBigRIPS ʹ͓͚Δߴਫ਼౓ύΠதؒࢠ‫ࢠݪ‬෼ޫɾೋॏ Gamow-Teller ‫ڊ‬େ‫ڞ‬໐୳ࡧ࣮‫ݕ৽͚ͨ޲ʹݧ‬ग़‫ث‬γεςϜͷੑೳධՁ (ii)ʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ, ౦‫ژ‬ཧՊେֶ, ໺ా, 2018 ೥ 3 ݄ 22–25 ೔.
ߴాलࠤ, ʮෳ߹֩‫ڞ‬໐ʹ͓͚Δ࣌ؒ൓సରশੑͷഁΕ୳ࡧ࣮‫ݧ‬ͷͨΊͷ Triplet-DNP Λ༻͍ͨதੑࢠεϐϯϑΟϧλʔͷ։ൃʯ,೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ, ౦‫ژ‬ཧՊେֶ, ໺ా, 2018 ೥ 3 ݄ 22–25 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Nuclear Science and Transmutation Research Division
Nuclear Spectroscopy Laboratory
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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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Members
Group 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
Tomoya SATO
Postdoctoral Researcher
Minori TAJIMA
Junior Research Associate
Keita KAWATA (Univ. of Tokyo)
International Program Associate
Aleksey GLADKOV (Kyungpook National Univ.)
Senior Visiting Scientists
Yukari MATSUO (Hosei Univ.)
Hideyuki SAKAI (Univ. of Tokyo)

Takaharu OTSUKA (Univ. of Tokyo)

Visiting Researcher
Hiroki NISHIBATA (JSPS Fellow)
Visiting Scientists
Wataru SATO (Kanazawa Univ.)
Kensaku MATSUTA (Osaka Univ.)
Jin NAKAMURA (Univ. of Elec.-Com.)
Satoshi TSUTSUI (JASRI)
Takamasa MOMOSE (Univ. of British Columbia)
Jean-Michel DAUGAS (CEA)
Yoshio KOBAYASHI (Univ. of Elec.-Com.)
Jiro MURATA (Rikkyo Univ.)
Jun MIYAZAKI (Hokuriku Univ.)
Yasuhiro YAMADA (Tokyo Univ. of Science)
Kenya KUBO (International Christian Univ.)

Akihiro YOSHIMI (Okayama Univ.)
Dimiter L. BALABANSKI (IHIN)
Naoki NISHIDA (Tokyo Univ. of Science)
Takeshi INOUE (Tohoku Univ.)
Yoko ISHIBASHI (Tohoku Univ.)
Kei IMAMURA (Okayama Univ.)
Takashi ABE (Univ. of Tokyo)
Deyan T. YORDANOV (IPN Orsay)
Georgi GEORGIEV (CNRS)
Andrew E. STUCHBERY (ANU)

Student Trainees
Masaomi TANAKA (Osaka Univ.)
Takafumi KAWAGUCHI (Hosei Univ.)
Makoto SANJO (Hosei Univ.)
Wataru KOBAYASHI (Hosei Univ.)
Yasuharu TAKEUCHI (Hosei Univ.)
Tomoaki YADA (Hosei Univ.)
Katsumi TOZUKA (Hosei Univ.)
Takumi ASAKAWA (Hosei Univ.)
Kazuho DOI (Hosei Univ.)
Yusuke SASAKI (Hosei Univ.)
Shota AMAGASA (Tokyo Univ. of Science)
Masanari SEKI (Tokyo Univ. of Science)
Honami ITO (Tokyo Univ. of Science)
Fuminori HATAYAMA (Tokyo Univ. of Science)

Kazuki HAMAZAKI (Tokyo Univ. of Science)
Takumi FUNABASHI (T Tokyo Univ. of Science)
Kenya TAKAHASHI (Univ. of Elec.-Com.)
Yutaro NAKAMURA (Meiji Univ.)
Takatoshi MAEKAWA (International Christian Univ.)
Aiko UCHIYAMA (Tohoku Univ.)
Taichi AKAOKA (Hosei Univ.)
Airi TODA (Hosei Univ.)
Yuika TAKEUCHI (Hosei Univ.)
Ryo TAKEMURA (Tokyo Univ. of Science)
Kyouichi IZUOKA (Tokyo Univ. of Science)
Timothy James GRAY (ANU)
Showen FANG (Univ. of Chicago)
Rafaela GSPONER (ETH Zurich)Interns
Dawei GUAN (Peking Univ.)
Yucai MAO (Peking Univ.)
Teng XIANG (Peking Univ.)
Gen LI (Peking Univ.)

Geliang LIU (Peking Univ.)
Seung Hyun PARK (Seoul National Univ.)
Mun Jung JUNG (Seoul National Univ.)
Kyuwon SEO (Seoul National Univ.)- 274 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Hyunsoo HA (Seoul National Univ.)
Jin NAMKUNG (Seoul National Univ.)
Ho Cheong TANG (The Univ. of Hong Kong)
Tik Tsun YEUNG (The Univ. of Hong Kong)

Yuen Shan TANG (The Univ. of Hong Kong)
Taranjit SINGH (The Univ. of Hong Kong)
Qingqing ZHAO (The Univ. of Hong Kong)
Kwok Lung FAN (The Univ. of Hong Kong)

Temporary Staﬃng
Yuka TAGUCHI

Emiko FUJINO

AssistantIzumi YOSHIDA

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
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. X. Watanabe, H. Wollnik, and S. Yamaki, “First mass measurements of nuclides around Z = 100 with a multireflection time-of-flightmass spectrograph,” Phys. Rev. Lett. 120, 152501 (2018). *O. B. Tarasov, D. S. Ahn, D. Bazin, N. Fukuda, A. Gade, M. Hausmann, N. Inabe, S. Ishikawa, N. Iwasa, K. Kawata, T. Komatsubara,
T. Kubo, K. Kusaka, D. J. Morrissey, M. Ohtake, H. Otsu, M. Portillo, T. Sakakibara, H. Sakurai, H. Sato, B. M. Sherrill, Y. Shimizu,
A. Stolz, T. Sumikama, H. Suzuki, H. Takeda, M. Thoennessen, H. Ueno, Y. Yanagisawa, and K. Yoshida, “Discovery of 60 Ca andimplifications for the stability of 70 Ca,” Phys. Rev. Lett. 121, 022501 (2018). *M. Hase, Y. Ebukuro, H. Kuroe, M. Matsumoto, A. Matsuo, K. Kindo, J. R. Hester, T. J. Sato, and H. Yamazaki, “Erratum: Magnetismof the antiferromagnetic spin-3/2 dimer compound CrVMoO7 having an antiferromagnetically ordered state [Phys. Rev. B 95, 144429(2017)],” Phys. Rev. B 98, 139901 (2018). *B. A. Marsh, T. Day Goodacre, S. Sels, Y. Tsunoda, B. Andel, A. N. Andreyev, N. A. Althubiti, D. Atanasov, A. E. Barzakh, 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, M. Huyse, S. Kreim, D. Lunney, K. M. Lynch, V. Manea, Y. Martinez Palenzuela, P. L. Molkanov, T. Otsuka, A. Pastore, M. Rosenbusch, 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, A. Zadvornaya, K. Zuber, “Characterization ofshape-staggering eﬀect in mercury nuclei,” Nat. Phys. 14, 1163 (2018). *S. Kimura, Y. Ito, D. Kaji, P. Schury, M. Wada, H. Haba, T. Hashimoto, Y. Hirayama, M. MacCormick, H. Miyatake, J. Y. Moon,
K. Morimoto, M. Mukai, I. Murray, A. Ozawa, M. Rosenbusch, H. Schatz, A. Takamine, T. Tanaka, Y. X. Watanabe, H. Wollnik,“Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-offlight mass spectrograph,” Int. J. Mass Spectrom. 430, 134 (2018). *Z. Y. Xu, H. Heylen, K. Asahi, F. Boulay, J. M. Daugas, R. P. de Groote, W. Gins, O. Kamalou, Á. Koszorús, M. Lykiardopoulou,
T. J. Mertzimekis, G. Neyens, H. Nishibata, T. Otsuka, R. Orset, A. Poves, T. Sato, C. Stodel, J .C. Thomas, N. Tsunoda, Y. Utsuno,
M. Vandebrouck, X. F. Yang, “Nuclear moments of the low-lying isomeric 1+ state of 34 Al: Investigation on the neutron 1p1h excitation
across N = 20 in the island of inversion,” Phys. Lett. B 782, 619–626 (2018). *K. Imamura, Y. Matsuo, W. Kobayashi, T. Egami, M. Sanjo, A. Takamine, T. Fujita, D. Tominaga, Y. Nakamura, T. Furukawa, T. Wakui,
Y. Ichikawa, H. Nishibata, T. Sato, A. Gladkov, L. C. Tao, T. Kawaguchi, Y. Baba, M. Iijima, H. Gonda, Y. Takeuchi, R. Nakazato,
H. Odashima, and H. Ueno, “Absolute optical absorption cross-section measurement of Rb atoms injected into superfluid helium using
energetic ion beams,” App. Phys. Exp. 12, 016502 (2019). *S. Kinbara, H. Ekawa, T. Fujita, S. Hayakawa, S.H. Hwang, Y. Ichikawa, K. Imamura, H. Itoh, H. Kobayashi, R. Murai, K. Nakazawa,
M.K. Soe, A. Takamine, A.M.M. Theint, H. Ueno, J. Yoshida, “Charge identification of low-energy particles for double-strangenessnuclei in nuclear emulsion,” Prog. Theor. Exp. Phys. 2019, 011H01 (2019). *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, Y. Kobayashi, S. Kojima, A. Kusoglu, T. Kawaguchi, T. Kawamura, 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. Tomonaga,
H. Ueno, H. Yamazaki and X. F. Yang, “Measurement of the magnetic moment of 75 Cu reveals the interplay between nuclear shellevolution and shape deformation,” Nat. Phys. 15, 321–325 (2019). *H. Nishibata, S. Kanaya, T. Shimoda, A. Odahara, S. Morimoto, A. Yagi, H. Kanaoka, M. R. Pearson, C. D. P. Levy, M. Kimura,
N. Tsunoda, and T. Otsuka, “Structure of 31 Mg: Shape coexistence revealed by β-γ spectroscopy with spin-polarized 31 Na,” Phys. Rev.
C 99, 024322 (2019). *Oral Presentations[International Conference etc.]
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,- 275 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

N. Inabe, Y. Ishibashi, Y. Kobayashi, S. Kojima, A. Kusoglu, T. Kawaguchi, T. Kawamura, 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. Tomonaga,
H. Ueno, H. Yamazaki and X. F. Yang, “Single-particle states and collective modes: results from magnetic moment measurement of
75m
Cu,” 10th International Conference on Direct Reactions with Exotic Beams (DREB2018), Matsue, Japan, June 4–8, 2018.
H. Nishibata (Invited), T. Shimoda, A. Odahara, S. Morimoto, S. Kanaya, A. Yagi, H. Kanaoka, M. R. Pearson, C. D. P. Levy, M. Kimura,
Shape coexistence in 31 Mg revealed by β- and β-γ spectroscopy with spin-polarize 31 Na,” The IX International Symposium on Exotic
Nuclei (EXON2018), Petrozavodsk, Russia, September 1–15 (2018).
A. Takamine (Invited), “Laser spectroscopy project at the SLOWRI facility in RIKEN,” 20th Northeastern Asian Symposium-2018 on
Nuclear Physics in the 21st Century, Naogya, Japan, September 18–19 (2018).
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, Y. Kobayashi, S. Kojima, A. Kusoglu, T. Kawaguchi, T. Kawamura, 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. Tomonaga,
H. Ueno, H. Yamazaki and X. F. Yang, “Magnetic moment of isomeric state of 75 Cu,” Fifth Joint Meeting of the Nuclear Physics
Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Sato (Invited), “Coexisting Xe-129 and Xe-131 masers with active feedback scheme for Xe atomic EDM search,” Fifth Joint Meetingof the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
H. Nishibata, S. Kanaya, T. Shimoda, A. Odahara, S. Morimoto, A. Yagi, H. Kanaoka, M. R. Pearson, C. D. P. Levy, M. Kimura,
N. Tsunoda, T. Otsuka, “Structure of neutron-rich 31 Mg by β-decay spectroscopy of spin-polarized 31 Na,” Fifth Joint Meeting of the
Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
A. Gladkov, Y. Ishibashi, H. Yamazaki, Y. Ichikawa, A. Takamine, H. Nishibata, K. Asahi, T. Sato, W. Y. Kim, T. Fujita, L. C. tao,
T. Egami, D. Tominaga, T. Kawaguchi, M. Sanjo, W. kobayashi, K. Imamura, Y. Nakamura, G. Georgiev, J. M. Daugas, H. Ueno,“β-NMR measurements of the ground-state nuclear moments for 21 O,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS
and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
K. Kawata, S. Ota, M. Dozono, S. Michimasa, H. Nishibata, C. Iwamoto, N. Kitamura, S. Matsuoka, R. Tsuonoda, T. Harada, H. Sakai,
N. Imai, K. Yako, T. Sato, “Production of isomers around 52 Fe nucleus via projectile fragmentation,” Fifth Joint Meeting of the Nuclear
Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Otsuka (Invited), “Quantum self-organization and nuclear collectivity,” Fifth Joint Meeting of the Nuclear Physics Divisions of the
APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
E. Ideguchi for the CAGRA collaboration, “Study of deformed structure in mass 40 region using CAGRA gamma-ray spectroscopy,”
Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27(2018).
S. Iimura, M. Fukutome, M. Hisamitsu, H. Umehara, S. Kanaya, H. Nishibata, A. Odahara, T. Shimoda, T, Hara, M. Kinoshita, T. Nakajima, R. Shudo, R. Wabayashi, “Precision half-life measurement of 18 N,” Fifth Joint Meeting of the Nuclear Physics Divisions of the
APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
H. Umehara, S. Iimura, S. Kanaya, H. Nishibata, A. Odahara, T. Shimoda, M. Kinoshita, R. Shudo, R. Nakajima, T. Hara, R. Wakabayashi,“Study of neutron unbound states in 18 O by β-delayed neutron decay of 18 N,” Fifth Joint Meeting of the Nuclear Physics Divisions of
the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
D. Nishimura, M. Fukuda, A. Honma, Y. Ichikawa, A. Kitagawa, K. Matsuta, M. Mihara, T. Ohtsubo, M. Tanaka, S. Sato, “BranchingRatio Measurements for Superallowed β Emitters at NIRS-HIMAC,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS
and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
M. Rosenbusch, H. Haba, Y. Hirayama, S. Ishizawa, Y. Ito, D. Kaji, S. Kimura, H. Koura, H. Miyatake, J. Y. Moon, K. Morimoto,
S. Nishimura, T. Niwase, P. Scury, A. Takamine, T. Tanaka, H. Ueno, M. Wada, Y. Watanabe, H. Wollnik, “Follow-Ups on Great
Achievements: New MRTOF-MS Projects at RIKEN-RIBF,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the
JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
H. Suzuki, K. Yoshida, H. Takeda, Y. Shimizu, D. S. Ahn, T. Sumikama, N. Inabe, T. Kobatsubara, H. Sato, Z. Korkulu, K. Kusaka,
Y. Yanagisawa, M. Ohtake, H. Ueno, S. Michimasa, N. Kitamura, K. Kawata, N. Imai, O. B. Tarasov, D. Bazin, T. Kubo, J. Nolen,
W. F. Henning, “Production of very neutron-rich Pd isotopes around N = 82 by projectile fragmentation of a RI beam of 132 Sn at
280 MeV/u,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA,
October 23–27 (2018).
S. Kimura, Y. Ito, D. Kaji, P. Schury, M. Wada, H. Haba, T. Hashimoto, Y. Hirayama, M. MacCormick, H. Miyatake, J. Y. Moon,
K. Morimoto, M. Mukai, I. Murray, A. Ozawa, M. Rosenbusch, H. Schatz, A. Takamine, T. Tanaka, Y. Watanabe, H. Wollnik, “Atomic
masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via MRTOF-MS,” Fifth Joint Meetingof the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
S. Masuoka, S. Shimoura, M. Takaki, S. Michimasa, S. Ota, M. Dozono, C. Iwamoto, K. Kawata, N. Kitamura, M. Kobayashi, R. Nakajima, H. Tokieda, R. Yokoyama for the SHARAQ 10 collaboration, “Re-measurement of the 4 He(8 He, 8 Be) reaction,” Fifth Joint
Meeting of the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
O. B. Tarasov, D. S. Ahn, D. Bazin, N. Fukuda, A. Gade, M. Hausmann, N. Inabe, S. Ishikawa, N. Iwaza, K. Kawata, T. Komatsubara,
T. Kubo, K. Kusaka, D. J. Morrisey, M. Ohtake, H. Otsu, M. Portillo, T. Sakakibara, H. Sakurai, H. Sato, B. M. Sherrill, Y. Shimizu,
A. Stolz, T. Sumikama, H. Suzuki, “Discovery of 60 Ca,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS(HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Abe, P. Maris, T. Miyagi, P. Navratil, T. Otsuka, N. Shimizu, Y. Utsuno, J. P. Vary, T. Yoshida, “Recent results and implications- 276 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)of no-core MCSM calculations for nuclear structure,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS(HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
N. Tsunoda, T. Otsuka, N. Shimizu, K. Takayanagi, M. Hjorth-Jense, T. Suzuki, “Study of neutron-rich nuclei via nuclear force andmicroscopic theory,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii,
USA, October 23–27 (2018).
S. Yoshida, N. Shimizu, T. Togashi, T. Otsuka, “Uncertainty quantification in nuclear shell-model calculations,” Fifth Joint Meeting of
the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Suzuki, T. Otsuka, N. Tsunoda, “Structure of neutron-rich carbon isotopes: shell evolution and two-neutron-halo at the dripline,” Fifth
Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27(2018).
A. Takamine (Invited), “Prospects for laser spectroscopy project at the SLOWRI facility in RIKEN RIBF,” 2018 KPS Fall Meeting,
Changwon, Korea, October 24–26 (2018).
T. Sato (Invited), “Atomic EDM searches in RIKEN,” The 10th China-Japan Joint Nuclear Physics Symposium (CJNP2018), Huizhou,
China, November 18–23 (2018).
H. Ueno (Invited), “R&D of spin-controlled RI beams,” The 10th China-Japan Joint Nuclear Physics Symposium (CJNP2018), Huizhou,
China, November 18–23 (2018).
M. Tajima (Invited), “Laser spectroscopy of RI beams at the SLOWRI facility of RIKEN,” The 10th China-Japan Joint Nuclear Physics
Symposium (CJNP2018), Huizhou, China, November 18–23 (2018).
T. Otsuka (Invited), “Messages from nuclear masses on the quantum phase transitions and the quantum self-organization,” The 10th
China-Japan Joint Nuclear Physics Symposium (CJNP2018), Huizhou, China, November 18–23 (2018).
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, Y. Kobayashi, S. Kojima, A. Kusoglu, T. Kawaguchi, T. Kawamura, 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. Tomonaga,
H. Ueno, H. Yamazaki and X. F. Yang, “Magnetic moment of 75m Cu measured with highly spin-aligned beam,” 13th International
Conference on Nucleus-Nucleus Collisions (NN2018), Omiya, Saitama, Japan, December 4–8 (2018).
H. Yamazaki, A. Gladkov, Y. Ishibashi, Y. Ichikawa, A. Takamine, H. Nishibata, K. Asahi, T. Sato, W. Y. Kim, T. Fujita, L. C. tao,
T. Egami, D. Tominaga, T. Kawaguchi, M. Sanjo, W. Kobayashi, K. Imamura, Y. Nakamura, G. Georgiev, J. M. Daugas, H. Ueno,“β-NMR/NQR spectroscopy as a local probe of condensed matter, ”Technical Meeting on Novel Multidisciplinary Applications with
Unstable Ion Beams and Complementary Techniques, Vienna, Austria, December 10–14 (2018).
Y. Ichikawa (Invited), “Nuclear magnetic dipole moments measured with spin-oriented RI beams at RIKEN RIBF,” The International
Conference on HYPERFINE Interactions and Applications (HYPERFINE 2019), Goa, India, February 10–15 (2019).
T. Sato (Invited), “129 Xe/131 Xe double-species spin maser for Xe-EDM search,” The 11th International Workshop on Fundamental Physics
Using Atoms (FPUA2019), Okinawa, Japan, March 1–4 (2019).

[Domestic Conference]ߴๆѪࢠʢট଴ߨԋʣ, ʮߴภ‫ ۃ‬RI ϏʔϜͷੜ੒ͱ֩ɾ෺࣭Պֶ‫΁ڀݚ‬ͷԠ༻ʯ, ৽ֶज़ྖҬ‫ڀݚ‬ʮӉ஦‫؍‬ଌ‫ݕ‬ग़‫ࢠྔͱث‬ϏʔϜͷग़ձ͍ɻ৽ͨͳԠ༻΁ͷՍ͚‫ڮ‬ɻʯΩοΫΦϑγϯϙδ΢Ϝ, ઋ୆, 2018 ೥ 12 ݄ 17–18 ೔.
ߴๆѪࢠ, Marco Rosenbusch, ࿨ాಓ࣏, Peter Schury, Jun-young Moon, Ԃా఩, খౡོ෉, ౉ᬒ༟, ยࢁҰ࿠, ্໺लथ, ੴࢁത߃,ʮཧ‫ ݚ‬RIBF SLOWRI ࢪઃʹ͓͚Δ RF ΠΦϯΨΠυΨεηϧ։ൃʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄ 14–17 ೔.
খྛߤ, ࠓଜ‫ܛ‬, ࡾᑍਅ, ౻ా๎ඒ, ߴๆѪࢠ, ‫ݹ‬઒෢, ্໺लथ, দඌ༝լར, ʮ௒ྲྀಈϔϦ΢Ϝத Ag ‫ʹࢠݪ‬ର͢Δೋॏ‫ڞ‬໐෼ޫ࣮‫ݧ‬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄ 14–17 ೔.
ࡾᑍਅ, ࠓଜ‫ܛ‬, খྛߤ, ஛಺༝ҥՖ, ߴๆѪࢠ, ‫ݹ‬઒෢, ্໺लथ, দඌ༝լར, ʮ௒ྲྀಈϔϦ΢Ϝத Rb ‫ࢠݪ‬ͷ௒ඍࡉߏ଄ִؒଌఆ
ͷͨΊͷ‫؍‬ଌ‫ิ਺ࢠݪ‬ਖ਼γεςϜʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄ 14–17 ೔.
੢ാᔨ‫ر‬ʢট଴ߨԋʣ, ʮภ‫ ۃ‬Na ϏʔϜͰ୳Δதੑࢠա৒‫ ֩ࢠݪ‬30 Mg, 31 Mg ͷଟ༷ͳ‫ߏ֩ࢠݪ‬଄ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄ 14–17 ೔.
େ௩޹࣏ʢট଴ߨԋʣ, ʮ‫֩ࢉܭ‬෺ཧͷల๬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄ 14–17 ೔.
ాౡඒయ, ʮDevelopment of oﬄine ion source for collinear laser spectroscopy of RI beamsʯ, ୈ 10 ճఀࢭɾ௿଎ RI ϏʔϜΛ༻͍ͨ֩෼ޫ‫ڀݚ‬ձʢ10th SSRIʣ, ෱Ԭ, 2019 ೥ 3 ݄ 18–19 ೔.
ࢢ઒༤Ұ, ʮෆ҆ఆ֩ͷ֩εϐϯภ‫ۃ‬ɾ੔ྻੜ੒ʹ͍ͭͯʯ, ୈ 10 ճఀࢭɾ௿଎ RI ϏʔϜΛ༻͍ͨ֩෼ޫ‫ڀݚ‬ձʢ10th SSRIʣ,෱Ԭ, 2019 ೥ 3 ݄ 18–19 ೔.
઒ా‫ܟ‬ଠ, ʮProduction of isomer around 52 Fe nucleus via projectile fragmentationʯ, ୈ 10 ճఀࢭɾ௿଎ RI ϏʔϜΛ༻͍ͨ֩෼ޫ
‫ڀݚ‬ձʢ10th SSRIʣ, ෱Ԭ, 2019 ೥ 3 ݄ 18–19 ೔.
੢ാᔨ‫ر‬, ʮεϐϯ੔ྻϏʔϜΛ༻͍ͨ֩Ϟʔϝϯτଌఆͱ֩෼ޫ‫΁ڀݚ‬ͷԠ༻ʯ, ୈ 10 ճఀࢭɾ௿଎ RI ϏʔϜΛ༻͍ͨ֩෼ޫ
‫ڀݚ‬ձʢ10th SSRIʣ, ෱Ԭ, 2019 ೥ 3 ݄ 18–19 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Nuclear Science and Transmutation Research DivisionHigh Energy Astrophysics Laboratory
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) ASTRO-H/Hitomi
The 6th Japanese X-ray satellite ASTRO-H/Hitomi was launched in February 2016. Hitomi carried four X-ray and gammaray 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. Although we were supposed to discover many previously-unknown elemental lines in universe and measured abundanceof those elements with SXS, Hitomi was unfortunately lost by an accident in March 2016. A recovery mission of Hitomi (named
XRISM) was started in 2017 and is now under construction for launch in 2021.
(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 2021, andwe have already provided the flight qualified GEMs to the project in FY2018.
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
magnetic field.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(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.

Members
Group Director
Toru TAMAGAWA
Research/Technical Scientist
Tatehiro MIHARA (Senior Research Scientist)
Contract Researcher
Takao KITAGUCHISpecial Postdoctoral Researchers
Toshio NAKANO
Shin’ya Nakashima

Liyi GU

Junior Research Associate
Ryo SASAKI (Chuo Univeristy)
Visiting Researcher
Asami HAYATO (JSPS Fellow)
Visiting Scientists
Tomoki KIMURA (Tohoku University)
Hirokazu ODAKA (Univeristy of Tokyo)
Yukikatsu TERADA (Saitama Univeristy)
Motohide KOKUBUN (ISAS/JAXA)
Masaki WAKABAYASHI (Jakulin Commercial Company LC)
Aya BAMBA (University of Tokyo)
Naohisa INADA (National Institute of Tech., Nara College)
Rohta TAKAHASHI (Tomakomai Nat’l College of Tech.)
Toru MISAWA (Shinshu Univeristy)
Yoko TAKEUCHI (TIRI)

Satoru KATSUDA (Saitama Univerisity)
Shin’ya YAMADA (Tokyo Metoropolitan University)
Yujin NAKAGAWA (JAMSTEC)
Teruaki ENOTO (Kyoto University)
Kazuki KOMIYA (TIRI)
Hirofumi NODA (Tohoku Univeristy)
Yuki OKURA (NAOJ)
Yuzuru TAWARA (Nagoya Univeristy)
Ikuyuki MITSUISHI (Nagoya Univeristy)
Harufumi TSUCHIYA (JAEA)

Student Trainees
Megu KUBOTA (Tokyo University of Science)
Yuuki WADA (University of Tokyo)
Naoto MURATA (Tokyo University of Science)
Sonoe ODA (Tokyo University of Science)
Yuanhui ZHOU (Tokyo University of Science)

Miho OKUBO (Tokyo University of Science)
Takaya WAKAMATSU (Tokyo University of Science)
Marina TSUTSUMI (Tokyo University of Science)
Keisuke UCHIYAMA (Tokyo University of Science)
Kento ADACHI (Tokyo University of Science)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
M. Kubota, T. Tamagawa, K. Makishima, T. Nakano, W. Iwakiri, M. Sugizaki, K. Ono, “An enigmatic hump around 30 keV in Suzaku
spectra of Aquila X-1 in the hard state,” Publ. Astron. Soc. Jpn. 71, 148 (2019). *The Hitomi collaboration, “Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector,”
Publ. Astron. Soc. Jpn. 70, 118 (2018). *M. Kubota, H. Odaka, T. Tamagawa, T. Nakano, “Discovery of redshifted He-like iron absorption line from luminous accreting neutronstar SMC X-1,” Astrophys. J. Lett. 868, L26 (2018). *O’ Dell, L. Stephen et al., “The imaging X-ray polarimetry explorer (IXPE): technical overview,” Proceedings of the SPIE 106991,
106991X (2018).
M. Tashiro et al., “Concept of the X-ray astronomy recovery mission,” Proceedings of the SPIE 10699, 1069922 (2018).
The Hitomi collaboration, “Hitomi X-ray observation of the pulsar wind nebula G21.5-0.9,” Publ. Astron. Soc. Jpn. 70, 027 (2018). *Y. Wada, G. S. Bowers, T. Enoto, M. Kamogawa, Y. Nakamura, T. Morimoto, D. M. Smith, Y. Furuta, K. Nakazawa, T. Yuasa, A. Matsuki,
M. Kubo, T. Tamagawa, K. Makishima, H. Tsuchiya, “Termination of electron acceleration in thundercloud by intracloud/interclouddischarge,” Geophys. Res. Lett. 45, 5700–5707 (2018). *- 279 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

T. Takahashi et al., “Hitomi (ASTRO-H) X-ray Astronomy Satellite,” J. Astron. Telesc. Instrum. Syst. 4, 21402 (2018). *M. Tsujimoto, K. Morihana, T. Hayashi, T. Kitaguchi,, “Suzaku and NuSTAR X-ray spectroscopy of γ Cassiopeiae and HD 110432,”
Publ. Astron. Soc. Jpn. 70, 109 (2018). *B. W. Grefenstette, W. R. Cook, F. A. Harrison, T. Kitaguchi, K. K. Madsen, H. Miyasaka, S. N. Pike, “Pushing the limits of NuSTAR
detectors,” Proceedings of the SPIE 10709, 107092 V (2018).
H. Tajima et al., “Design and performance of Soft Gamma-ray Detector onboard the Hitomi (ASTRO-H) satellite,” J. Astron. Teles.
Instrum. Syst. 4, 21411 (2018). *S. Nakahira, M. Shidatsu, K. Makishima, Y. Ueda, K. Yamaoka, T. Mihara, H. Negoro, T. Kawase, N. Kawai, K. Morita, “Discovery andstate transitions of the new Galactic black hole candidate MAXI J1535-571,” Publ. Astron. Soc. Jpn. 70, 95 (2018). *F. Yatabe, K. Makishima, T. Mihara, M. Nakajima, M. Sugizaki, S. Kitamoto, Y. Yoshida, T. Takagi, “An application of the Ghosh &Lamb model to the accretion-powered X-ray pulsar X Persei,” Publ. Astron. Soc. Jpn. 70, 89 (2018). *T. Kawamuro, Y. Ueda, M. Shidatsu, T. Hori, M. Morii, S. Nakahira, N. Isobe, N. Kawai, T. Mihara, M. Matsuoka, T. Morita, M. Nakajima,
H. Negoro, S. Oda, T. Sakamoto, M. Serino, M. Sugizaki, A. Tanimoto, H. Tomida, Y. Tsuboi, H. Tsunemi, S. Ueno, K. Yamaoka,
S. Yamada, A. Yoshida, W. Iwakiri, Y. Kawakubo, Y. Sugawara, S. Sugita, Y. Tachibana, T. Yoshii, “The 7-year MAXI/GSC X-ray
source catalog in the high Galactic latitude sky (3MAXI),” Astrophys. J. Suppl. Ser. 238, 32 (2018). *S. Sugita, N. Kawai, S. Nakahira, H. Negoro, M. Serino, T. Mihara, K. Yamaoka, M. Nakajima, “MAXI upper limits of the electromagnetic
counterpart of GW170817,” Publ. Astron. Soc. Jpn. 70, 70 (2018). *K. Yoshida, D. Yonetoku, M. Arimoto, T. Sawano, Y. Kagawa, M. Ina, K. Ota, D. Suzuki, K. Miyao, S. Watanabe, T. Mihara, Y. Takao,
H. Ikeda, S. Yagitani, Y. Kasahara, T. Imachi, T. Kita, K. Kawagoshi, H. Segawa, T. Nakashima, T. Minamoto, K. Kyutoku, “KanazawaSAT3: micro-satellite mission for monitoring x-ray transients coincide with gravitational wave events,” Proceedings of the SPIE 10699,
1069962 (2018).
M. Takahashi, Y. Inome, S. Yoshii, A. Bamba, S. Gunji, D. Hadasch, M. Hayashida, H. Katagiri, Y. Konno, H. Kubo, J. Kushida,
D. Nakajima, T. Nakamori, T. Nagayoshi, K. Nishijima, S. Nozaki, D. Mazin, S. Mashuda, R. Mirzoyan, H. Ohoka, R. Orito, T. Saito,
S. Sakurai, J. Takeda, M. Teshima, Y. Terada, F. Tokanai, T. Yamamoto, T. Yoshida, “A technique for estimating the absolute gain of aphotomultiplier tube,” Nucl. Instrum. Methods Phys. Res. A 894, 1 (2018). *K. Nakazawa et al., “Hard x-ray imager onboard Hitomi (ASTRO-H),” J. Astron. Teles. Instrum. Syst. 4, 21410 (2018). *K. Hagino et al., “In-orbit performance and calibration of the Hard X-ray Imager onboard Hitomi (ASTRO-H),” J. Astron. Teles. Instrum.
Syst. 4, 21409 (2018). *A. Simionescu, S. Nakashima, H. Yamaguchi, K. Matsushita, F. Mernier, N. Werner, T. Tamura, K. Nomoto, J. de Plaa, S. -C. Leung,
A. Bamba, E. Bulbul, M. E. Eckart, Y. Ezoe, A. C. Fabian, Y. Fukazawa, L. Gu, Y. Ichinohe, M. N. Ishigaki, J. S. Kaastra, C. Kilbourne,
T. Kitayama, M. Leutenegger, M. Loewenstein, Y. Maeda, E. D. Miller, R. F. Mushotzky, H. Noda, C. Pinto, F. S. Porter, S. Safi-Harb,
K. Sato, T. Takahashi, S. Ueda, S. Zha, “Constraints on the chemical enrichment history of the Perseus Cluster of galaxies fromhigh-resolution X-ray spectroscopy,” Mon. Not. R. Astron. Soc. 483, 1701–1721 (2019). *H. Yamaguchi, T. Tanaka, D. R. Wik, J. Rho, A. Bamba, D. Castro, R. K. Smith, A. R. Foster, H. Uchida, R. Petre, B. J. Williams,“Evidence for rapid adiabatic cooling as an origin of the recombining plasma in the supernova remnant W49B revealed by NuSTAR
observations,” Astrophys. J. Lett. 868, L35 (2018). *T. Kasuga, T. Sato, K. Mori, H. Yamaguchi, A. Bamba, “Asymmetric expansion of the Fe ejecta in Kepler’s supernova remnant,” Publ.
Astron. Soc. Jpn. 70, 88 (2018). *S. Nakashima, Y. Inoue, N. Yamasaki, Y. Sofue, J. Kataoka, K. Sakai, “Spatial distribution of the Milky Way hot gaseous halo constrainedby Suzaku X-ray observations,” Astrophys. J. 862, 34 (2018). *M. Akita, J. Kataoka, M. Arimoto, Y. Sofue, T. Totani, Y. Inoue, S. Nakashima, “Diﬀuse X-ray emission from the northern arc of loop iobserved with Suzaku,” Astrophys. J. 862, 88 (2018). *M. Katsuragawa, S. Nakashima, H. Matsumura, T. Tanaka, H. Uchida, S. -H. Lee, Y. Uchiyama, M. Arakawa, T. Takahashi, “Suzaku
X-ray observations of the mixed-morphology supernova remnant CTB 1,” Publ. Astron. Soc. Jpn. 70, 110 (2018). *F. Fraschetti, S. Katsuda, T. Sato, J. R. Jokipii, J. Giacalone, “Vortical amplification of the magnetic field at an inward shock of supernova
remnant Cassiopeia A,” Phys. Rev. Lett. 120, 251101 (2018). *L. Gu, J. Mao, J. de Plaa, A. J. J. Raassen, C. Shah, J. S. Kaastra, “Charge exchange in galaxy clusters,” Astronomy & Astrophysics 611,
A26 (2018). *J. Mao, J. de Plaa, J. S. Kaastra, C. Pinto, L. Gu, F. Mernier, H. -L. Yan, Y. -Y. Zhang, H. Akamatsu, “Nitrogen abundance in the X-ray
halos of clusters and groups of galaxies,” Astronomy & Astrophysics 621, A9 (2019). *F. Mernier, N. Werner, J. de Plaa, J. S. Kaastra, A. J. J. Raassen, L. Gu, J. Mao, I. Urdampilleta, A. Simionescu, “Solar chemicalcomposition in the hot gas of cool-core ellipticals, groups, and clusters of galaxies,” Mon. Not. R. Astron. Soc. 480, L95 (2018). *F. Mernier, J. de Plaa, N. Werner, J. S. Kaastra, A. J. J. Raassen, L. Gu, J. Mao, I. Urdampilleta, N. Truong, A. Simionescu, “Massinvariance of the iron enrichment in the hot haloes of massive ellipticals groups, and clusters of galaxies,” Mon. Not. R. Astron. Soc.
478, L116 (2018). *T. Akahori, Y. Kato, K. Nakazawa, T. Ozawa, L. Gu, M. Takizawa, Y. Fujita, H. Nakanishi, N. Okabe, K. Makishima, “ATCA 16 cm
observation of CIZA J1358.9-4750: Implication of merger stage and constraint on non-thermal properties,” Publ. Astron. Soc. Jpn. 70,
53 (2018). *- 280 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Oral Presentations[International Conference etc.]
T. Tamagawa, (Invited), “Imaging X-ray polarimeter explorer (IXPE),” New Eyes on X-ray Astronomical Objects with Japanese andChinese Observatories, Sagamihara, Japan, November 19, 2018.
S. Nakashima, K. Matsushita, XARM pre-project team, “Status of the XARM mission,” The eROSITA Consortium Meeting, Garching,
Germany, April 24, 2018.
S. Nakashima, J. Kataoka, M. Akita, Y. Inoue, Y. Soufe, N. Yamasaki, K. Sakai, “X-ray & Gamma-ray observations of the Fermi bubbles,”Frontier Research in Astrophysics-III Mondello Workshop 2018, Palermo, Italy, May 29, 2018.
S. Nakashima, on behalf of the Hitomi collaboration, “Highlights of the Hitomi X-ray observatory,” Frontier Research in Astrophysics-III
Mondello Workshop 2018, Palermo, Italy, May 30, 2018.
T. Sato, “Kinematical asymmetries and their interpretations in Kepler’s supernova remnant and Cassiopeia A,” Shocking Supernovae:
surrounding interactions and unusual events, Stockholm, Sweden, May 28, 2018.
L. Gu, “Atomic data and plasma code needed for XRISM and Athena,” AtomDB Workshop 2018, CfA, Cambridge, USA, November 1,
2018.
L. Gu, “Results from the Hitomi satellite,” X-ray Astronomy workshop 2018, Bonn, Germany, June 24, 2018.
L. Gu, “Atomic data and plasma code for future X-ray spectroscopy,” RIKEN Workshop on Atomic Physics 2018, Wako, Japan, May 30,
2018.

[Domestic Conference]಺ా࿨ւ, ʮೆ‫ۃ‬पճ‫ʹٿؾ‬ΑΔߗ X ઢภޫ‫؍‬ଌϛογϣϯ X-Calibur ͷ‫ݱ‬ঢ়ͱࠓ‫ޙ‬ʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018
೥ 9 ݄ 19–21 ೔.
ࡾੴҮ೭, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ΁ͷࢀՃ‫ݱ‬ঢ় (2)ʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9 ݄ 19–21 ೔.
ೋଜହհ, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ౥ࡌ X ઢ๬ԕ‫༻ڸ‬डಈ‫ܕ‬೤੍‫ޚ‬ૉࢠαʔϚϧγʔϧυͷ։ൃ (3)ʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9 ݄ 19–21 ೔.
খాԓձ, ʮϒϥοΫϗʔϧ X ઢ࿈੕ MAXI J1828-249 ͷ X ઢ͓ΑͼՄࢹޫ‫؍‬ଌʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥
9 ݄ 19–21 ೔.
‫ܙాۼ‬, ʮେ࣭ྔ X ઢ࿈੕ SMC X-1 ͔Βͷߴి཭మ‫ٵ‬ऩઢͷൃ‫ͦͱݟ‬ͷ‫ݯى‬ʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9݄ 19–21 ೔.
ᖒ໺ୡ࠸, ʮॏྗ೾‫ ݯ‬X ઢରԠఱମ୳ࠪ‫ܭ‬ը Kanazawa-SAT3 ϑϥΠτϞσϧ੡࡞ঢ়‫( گ‬2)ʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏,2018 ೥ 9 ݄ 19–21 ೔.
ླ໦େஐ, ʮ௒খ‫ܕ‬Ӵ੕౥ࡌ޿ࢹ໺ X ઢࡱ૾‫ݕ‬ग़‫ث‬ͷࡱ૾ੑೳධՁʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9 ݄ 19–21 ೔.
౉ลজଡ, ʮ௒খ‫ܕ‬Ӵ੕౥ࡌΨϯϚઢ‫ݕ‬ग़‫࡞ࢼث‬ϞσϧͷධՁʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9 ݄ 19–21 ೔.
ࠜိ‫ۉ‬, ʮ̭ઢ৽੕ MAXI J1727-203 ͷൃ‫ ͱݟ‬MAXI/GSC ͕‫ݕ‬ग़ͨ͠ 2018 ೥౓લ൒ͷಥൃ‫ݱ‬৅ʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9 ݄ 19–21 ೔.
தౡ‫ج‬थ, ʮMAXI, Swift, RXTE ʹΑΔ X ઢ࿈੕ύϧαʔ GS 1843-02 ͷ‫ي‬ಓҐ૬ʹґଘͨ͠ X ઢεϖΫτϧมಈʯ, ೔ຊఱจֶ
ձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9 ݄ 19–21 ೔.
େࢬ‫װ‬, ʮBe/X ઢ࿈੕ύϧαʔ Swift J0243.6+6124 ͷ Eddington ޫ౓ۙ๣ʹ͓͚Δ X ઢεϖΫτϧɼύϧε೾‫ܗ‬ͷมԽʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9 ݄ 19–21 ೔.
‫੾ؠ‬ব, ʮMAXI-NICER ࿈‫( ܞ‬MANGA) ʹΑΔ‫ڊ‬େ߃੕ϑϨΞͷೈ X ઢ‫؍‬ଌʯ, ೔ຊఱจֶձ 2018 ೥ळ‫ق‬೥ձ, ඣ࿏, 2018 ೥ 9 ݄
19–21 ೔.
๺‫وޱ‬༤, ʮ‫ػ‬ցֶशΛ༻͍ͨඈ੻ը૾ॲཧʹΑΔޫిࢠ௥੻‫ ܕ‬X ઢภޫ‫ܭ‬ͷ‫্޲౓ײ‬ʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, দຊ, 2018 ೥ 9݄ 14–17 ೔.
ᖒ໺ୡ࠸, ʮॏྗ೾ରԠ X ઢಥൃఱମ୳ࠪ௒খ‫ܕ‬Ӵ੕‫ܭ‬ը Kanazawa-SAT3 ʹ͓͚Δ X ઢࡱ૾‫ݕ‬ग़‫ث‬ϑϥΠτϞσϧ։ൃঢ়‫گ‬ʯ,೔ຊ෺ཧֶձळ‫ق‬େձ, দຊ, 2018 ೥ 9 ݄ 14–17 ೔.
ߴඌ༞հ, ʮKanazawa-SAT3 ΨϯϚઢόʔετ༻ΨϯϚઢ‫ݕ‬ग़‫ث‬ʯ, ೔ຊ෺ཧֶձळ‫ق‬େձ, দຊ, 2018 ೥ 9 ݄ 14–17 ೔.
‫ۄ‬઒ ప, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPEʯ, ୈ 15 ճ MPGD ‫ڀݚ‬ձ, ‫౎ژ‬, 2018 ೥ 12 ݄ 14–15 ೔.
಺ࢁ‫ܚ‬༞, ʮIXPE Ӵ੕౥ࡌ༻ GEM ͷ੡࡞ͱੑೳධՁʯ, ୈ 15 ճ MPGD ‫ڀݚ‬ձ, ‫౎ژ‬, 2018 ೥ 12 ݄ 14–15 ೔.
෢಺ཅࢠ, ʮLTCC-GEM ͷՃ޻ਫ਼౓ͷଌఆʯ, ୈ 15 ճ MPGD ‫ڀݚ‬ձ, ‫౎ژ‬, 2018 ೥ 12 ݄ 14–15 ೔.
ੴ࡚‫ۍ‬ঘ, ʮX ઢ෼ޫࡱ૾Ӵ੕ (XRISM) ౥ࡌ Resolve ͷ։ൃঢ়‫گ‬ʯ, Ӊ஦Պֶγϯϙδ΢Ϝ, ૬໛‫ݪ‬, 2019 ೥ 1 ݄ 9–10 ೔.
ૣ౻ຑඒ, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ౥ࡌʹ޲͚ͨภޫ‫༻ܭ‬Ψεిࢠ૿෯ϑΥΠϧͷ։ൃʯ, Ӊ஦Պֶγϯϙδ΢Ϝ, ૬໛‫ݪ‬, 2019
೥ 1 ݄ 9–10 ೔.
ߴ‫ॆ߂ڮ‬, ʮߗ X ઢूޫภޫ‫ ܭ‬X-Calibur ‫ݧ࣮ٿؾ‬ͷ 2018 ೥ϑϥΠτͱকདྷ‫ܭ‬ըʯ, Ӊ஦Պֶγϯϙδ΢Ϝ, ૬໛‫ݪ‬, 2019 ೥ 1 ݄
9–10 ೔.
ਫ໺߃࢙, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPEʯ, Ӊ஦Պֶγϯϙδ΢Ϝ, ૬໛‫ݪ‬, 2019 ೥ 1 ݄ 9–10 ೔.
ࡾੴҮ೭, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ౥ࡌʹ޲͚ͨ๬ԕ‫༻ڸ‬αʔϚϧγʔϧυͷ։ൃʯ, Ӊ஦Պֶγϯϙδ΢Ϝ, ૬໛‫ݪ‬, 2019 ೥ 1
݄ 9–10 ೔.
ాଜ‫ีܒ‬, ʮೆ‫ۃ‬पճ‫ʹٿؾ‬ΑΔߗ X ઢภޫ‫؍‬ଌ࣮‫ ݧ‬X-Calibur ͷ 2021 ೥কདྷϑϥΠτ΁޲͚ͯʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
ߴ‫ॆ߂ڮ‬, ʮߗ X ઢภޫ‫؍‬ଌ࣮‫ ݧ‬X-Calibur ͷ 2018–2019 ೥‫ٿؾ‬ϑϥΠτʹ޲͚ͨ४උঢ়‫گ‬ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ,- 281 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
ࡾੴҮ೭, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ΁ͷࢀՃ‫ݱ‬ঢ় (3)ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
ਗ਼ਫఃߦ, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ౥ࡌ X ઢ๬ԕ‫༻ڸ‬डಈ‫ܕ‬೤੍‫ޚ‬ૉࢠαʔϚϧγʔϧυͷ։ൃ (4)ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
༶ႌ, ʮXMM Ӵ੕σʔλΛ༻͍ͨ MCXCJ0157.4-0550 ͷ 2 ࣍‫ݩ‬Թ౓ີ౓ߏ଄ͷղੳ 2ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ,2019 ೥ 3 ݄ 14–17 ೔.
ӿ‫ًށ‬༲, ʮͦ͞Γ࠲ X-1 ͷ̭ઢϞχλϦϯάʹಛԽͨ͠௒খ‫ܕ‬Ӵ੕ϓϩδΣΫτߏ૝ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ,2019 ೥ 3 ݄ 14–17 ೔.
ྛଟՂ༝, ʮ‫࣓ڧ‬৔ܹม੕൓ࣹ X ઢϞσϧͷ V1223 Sagittarii ΁ͷద༻ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄
14–17 ೔.
ࠤʑ໦྄, ʮMAXI-NICER ࿈‫ܞ‬ʢMANGAʣʹΑΔ RS CVn ‫ܕ‬੕ GT Mus ͷ‫ڊ‬େϑϨΞ‫؍‬ଌʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ,খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
ਿ࡚ກ, ʮॏྗ೾ʹରԠͨ͠ X ઢ์ࣹͷ‫؍ࢹ؂‬ଌͷͨΊͷ MAXI ͷӡ༻ঢ়‫گ‬ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3
݄ 14–17 ೔.
ཥ৾, ʮLobster Eye ޫֶ‫ܥ‬ͷ GEANT4 γϛϡϨʔγϣϯʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
ᖒ໺ୡ࠸, ʮॏྗ೾‫ ݯ‬X ઢରԠఱମ୳ࠪ‫ܭ‬ը Kanazawa-SAT3 ϑϥΠτϞσϧ੡࡞ঢ়‫( گ‬3)ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ,2019 ೥ 3 ݄ 14–17 ೔.
ઙҪ࿨ඒ, ʮதੑࢠ੕௿࣭ྔ X ઢ࿈੕ͷ௕‫ظ‬มಈʹ͍ͭͯʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
ࠜိ‫ۉ‬, ʮ̭ઢ৽੕ MAXI J1810-222 ͷൃ‫ ͱݟ‬MAXI/GSC ͕‫ݕ‬ग़ͨ͠ 2018 ೥౓‫ޙ‬൒ͷಥൃ‫ݱ‬৅ʯ, ೔ຊఱจֶձ 2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
Տ߹੣೭, ʮϚάωλʔ XTE J1810-197 ͷಥൃ X ઢ૿ޫͷ MAXI ʹΑΔൃ‫ ͱݟ‬NuSTAR ʹΑΔϑΥϩʔΞοϓʯ, ೔ຊఱจֶձ
2019 ೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
‫੾ؠ‬ব, ʮRXTE Ӵ੕͕ଊ͑ͨ X ઢόʔελʔ EXO 1745-248 ͷεʔύʔόʔετऴྃ௚‫ޙ‬ͷ‫ً͍ڧ‬ઢߏ଄ʯ, ೔ຊఱจֶձ 2019೥य़‫ق‬೥ձ, খۚҪ, 2019 ೥ 3 ݄ 14–17 ೔.
࿨ా༗‫ر‬, ʮཕ‫׆‬ಈʹ༝དྷ͢ΔΨϯϚઢͷ‫؍‬ଌϓϩδΣΫτɿଟ஍఺‫؍‬ଌͷਐలͱେ‫ిؾ‬৔ɾి೾ͱͷ‫ڠ‬ಉ‫؍‬ଌʯ, ೔ຊ෺ཧֶձୈ
74 ճ೥࣍େձ, ҏ౎, 2019 ೥ 3 ݄ 14–17 ೔.
খߴ༟࿨, ʮ໌Δ͍߱ண‫ܕ‬ύϧαʔ SMC X-1 ͔Βͷߴి཭మ‫ٵ‬ऩઢͷൃ‫ͦͱݟ‬ͷղऍʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ҏ౎, 2019
೥ 3 ݄ 14–17 ೔.
‫ۄ‬઒ప, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPEɿϓϩδΣΫτ֓ཁͱਐ௙ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ҏ౎, 2019 ೥ 3 ݄ 14–17 ೔.
‫࢘܊‬मҰ, ʮX ઢภޫ‫؍‬ଌӴ੕ IXPE ͰͷϒϥοΫϗʔϧ‫؍‬ଌʹ͓͚Δղੳख๏ͷ‫ڀݚ‬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ҏ౎,2019 ೥ 3 ݄ 14–17 ೔.
ߴ‫ॆ߂ڮ‬, ʮߗ X ઢूޫภޫ‫ ܭ‬X-Calibur ‫ݧ࣮ٿؾ‬ͷ 2018 ೥ϑϥΠτͱকདྷ‫ܭ‬ըʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ҏ౎, 2019 ೥
3 ݄ 14–17 ೔.
େ‫ٱ‬อඒึ, ʮߴΤωϧΪʔ X ઢͷภޫΛ‫ݕ‬ग़͢Δ Time Projection Chamber ‫ܕ‬ภޫ‫ܭ‬ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ,ҏ౎, 2019 ೥ 3 ݄ 14–17 ೔.
‫ాۼ‬Ί͙, ʮAquila X-1ʮ͘͢͟ʯεϖΫτϧʹ͓͚Δ 30 keV ෇ۙͷະղ໌ͳϋϯϓߏ଄ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ҏ౎,2019 ೥ 3 ݄ 14–17 ೔.

- 282 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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- 283 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)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.

Members
Group Director
Kosuke MORITA
Visiting Scientist
Kunihiro FUJITA (Kyushu Univ.)

List of Publications & Presentations
Oral Presentations[International Conference etc.]
K. Morita, “Present Status and Perspectives of SHE Researches at RIKEN,” 13th International Conference on Nucleus-Nucleus Collisions(NN2018), Ohmiya, Saitama, Japan, December 4, 2018.

[Others]
৿ాߒհ, प‫ظ‬ද 150 ೥‫ه‬೦γϯϙδ΢Ϝ, ʮୈ 113 ൪৽‫ݩ‬ૉχϗχ΢Ϝͷൃ‫ݟ‬ʯ, ֶज़ձٞߨಊ, 2019 ೥ 2 ݄ 23 ೔.
৿ాߒհ, ʮ৽‫ݩ‬ૉͷ୳ࡧʯ, ࣛࣇౡதԝߴ౳ֶߍ SSH, ࣛࣇౡதԝߴߍମҭ‫ؗ‬, 2018 ೥ 9 ݄ 4 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Nuclear Science and Transmutation Research Division
Superheavy Element Research Group
Superheavy Element Production Team
1. Abstract

The elements with atomic number Z > 103 are called as trans-actinide or superheavy elements (SHEs). Superheavy Element
Production Team investigates synthesis 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

3. 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 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 theelements 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, to continue SHE studies at RIBF, we moved GAs-filled Recoil
Ion Separator II (GARIS II) from the irradiation room of RILAC to the E6 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.
(2) Decay spectroscopy of the heaviest nuclei
We measured precision masses of 63 Cu, 64–66 Zn, 65 Ga, 65–67 Ge, 67 As, 78, 81 Br, 80 Rb, 79 Sr, 210–214 Ac, 210–214 Ra, 246 Es, 251 Fm,
249–252
Md, and 254 No using a multireflection time-of-flight mass spectrograph coupled to GARIS II at RILAC mainly in collaboration
with High Energy Accelerator Research Organization.
(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 the fusion
process is still not well understood both theoretically and experimentally. In collaboration with Kyushu Univ., we measured excitation
functions for the quasielastic scattering of the 208 Pb + 48 Ca, 208 Pb + 50 Ti, 238 U + 48 Ca, 248 Cm + 22 Ne, 248 Cm + 26 Mg, 248 Cm + 30 Si,
248
Cm + 34 S, 248 Cm + 40 Ar, 248 Cm + 48 Ca, and 248 Cm + 50 Ti 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 (Z ≥ 104) is an extremely interesting and challenging subject in modern
nuclear and radiochemistry. 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
transport system to the focal plane of GARIS at RILAC. This system is a 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 conditions make it possible
to investigate new chemical systems. We have been developing an ultra-rapid gas-chromatograph apparatus at the focal plane of
GARIS. This apparatus consists of an RF carpet gas cell and a cryo-gas-chromatograph column with Si detector array. For theaqueous chemistry of SHEs, we have been developing a flow solvent extraction apparatus which consists of a continuous dissolution
apparatus, a flow extraction apparatus, and a liquid scintillation counter.

Members
Team Leader
Hiromitsu HABA

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Research/Technical Scientist
Daiya KAJI
Junior Research Associate
Taiki TANAKA
Visiting Scientists
Satoshi ADACHI (Kyushu Univ.)
Marc ASFARI (Institut Pluridisciplinaire Hubert Curien)
Olivier DORVAUX (Institut Pluridisciplinaire Hubert Curien)
Satoshi SAKAGUCHI (Kyushu Univ.)
Mirei TAKEYAMA (Yamagata Univ.)
Benoit Jean-Paul GALL (Strasbourg Univ.)
Student Trainees
Takeshi HIRANO (Kyushu Univ.)
Natsuki NAITO (Kyushu Univ.)
Takahiro HIRAKAWA (Kyushu Univ.)
Toshitaka NIWASE (Kyushu Univ.)
Kieran KESSACI (Strasbourg Univ.)

Masaomi TANAKA (Kyushu Univ.)
Zaiguo GAN (Institute of Modern Physics)
Huabin YANG (Institute of Modern Physics)
Shintaro GO (Kyushu Univ.)
Zhiyuan ZHANG (Institute of Modern Physics)
Hiroyuki KOURA (Japan Atomic Energy Agency)
Kazuya SHIRASAKA (Kyushu Univ.)
Shun MITSUOKA (Kyushu Univ.)
Yoshihide SUEKAWA (Kyushu Univ.)
Ikuto MURAKAMI (Kyushu Univ.)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
M. Rosenbusch, Y. Ito, P. Schury, M. Wada, D. Kaji, K. Morimoto, H. Haba, S. Kimura, H. Koura, M. MacCormick, H. Miyatake,J. Y. Moon, K. Morita, I. Murray, T. Niwase, A. Ozawa, M. Reponen, A. Takamine, T. Tanaka, H. Wollnik, “New mass anchor points
for neutron-deficient heavy nuclei from direct mass measurements of radium and actinium isotopes,” Phys. Rev. C 97, 064306 1–8(2018).*
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. X. Watanabe, H. Wollnik, S. Yamaki, “First direct mass measurements of nuclides around Z = 100 with a multireflection time-offlight mass spectrograph,” Phys. Rev. Lett. 120, 152501 1–6 (2018).*
S. Kimura, Y. Ito, D. Kaji, P. Schury, M. Wada, H. Haba, T. Hashimoto, Y. Hirayama, M. MacCormicke, H. Miyatake, J. Y. Moon,
K. Morimoto, M. Mukai, I. Murray, A. Ozawa, M. Rosenbusch, H. Schatz, A. Takamine, T. Tanaka, Y. X. Watanabe, H. Wollnik,“Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-offlight mass spectrograph,” Int. J. Mass Spectrom. 430, 134–142 (2018).*
K. Morita, K. Morimoto, D. Kaji, H. Haba, H. Kudo, “Discovery of new element, nihonium, and perspectives,” Prog. Nucl. Sci. Technol.
5, 8–13 (2018).*
L. Lens, A. Yakushev, C. E. Düllmann, M. Asai, J. Ballof, M. Block, H. M. David, J. Despotopulos, A. D. Nitto, K. Eberhardt, J. Even,
M. Götz, S. Götz, H. Haba, L. Harkness-Brennan, F. P. Heßberger, R. D. Herzberg, 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, J. Runke, M. Schädel, P. Scharrer, T. Sato,
D. Shaughnessy, B. Schausten, P. Thörle-Pospiech, N. Trautmann, K. Tsukada, J. Uusitalo, A. Ward, M. Wegrzecki, N. Wiehl, V. Yakusheva, “Online chemical adsorption studies of Hg, Tl, and Pb on SiO2 and Au surfaces in preparation for chemical investigations on
Cn, Nh, and Fl at TASCA,” Radiochim. Acta 106, 949–962 (2018).*
T. Tanaka, K. Morita, “Optimum incident energy for new element search,” AAPPS (Association of Asia Pacific Physical Societies)
Bulletin 28, 28–30 (2018).
H. Haba, “A new period in superheavy-element hunting,” Nat. Chem. 11, 10–13 (2019).*
A. Yokoyama, Y. Kitayama, Y. Fukuda, H. Kikunaga, M. Murakami, Y. Komori, S. Yano, H. Haba, K. Tsukada, A. Toyoshima, “Extraction
behavior of rutherfordium as a cationic fluoride complex with a TTA chelate extractant from HF/HNO3 acidic solutions,” Radiochim.
Acta 107, 27–32 (2019).*
Y. Wang, S. Cao, J. Zhang, F. Fan, J. Yang, H. Haba, Y. Komori, T. Yokokita, K. Morimoto, D. Kaji, Y. J. Wittwer, R. Eichler, A. Türler,
Z. Qin, “The study of rhenium pentacarbonyl complexes using single-atom chemistry in gas phase,” Phys. Chem. Chem. Phys. 21,
7147–7154 (2019).*
I. Tsekhanovich, A. N. Andreyev, K. Nishio, D. Denis-Petit, K. Hirose, H. Makii, Z. Matheson, K. Morimoto, K. Morita, W. Nazarewicz,
R. Orlandi, J. Sadhukhan, T. Tanaka, M. Vermeulen, M. Warda, “Observation of the competing fission modes in 178 Pt,” Phys. Lett. B
790, 583–588 (2019).*Ӌ৔޺ޫ, ʮGARIS ͕୓͘௒ॏ‫ݩ‬ૉͷԽֶ—106 ൪‫ݩ‬ૉγʔϘʔΪ΢ϜͷΧϧϘχϧࡨମͷ߹੒—ʯ, Radioisotopes 67, 527–535(2018).*
Ӌ৔޺ޫ, ʮ௒ॏ‫ݩ‬ૉͷ߹੒—‫ࢠݪ‬൪߸ 113 Ҏ߱ͷ௒ॏ‫ݩ‬ૉͷ߹੒ͱൃ‫—ݟ‬ʯ, Radioisotopes 67, 277–289 (2018).*- 286 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)ాதହ‫و‬, ৿ాߒհ, ʮ৽‫ݩ‬ૉ୳ࡧͷ࠷దͳೖࣹΤωϧΪʔʯ, ೔ຊ෺ཧֶձࢽ 73, 234–235 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 1. ‫ݩ‬ૉͷൃ‫ͱݟ‬प‫ظ‬දʯ, ‫ݱ‬୅Խֶ 4, No. 565, 34–37 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 2. ಉҐମͱ֩ਤදʯ, ‫ݱ‬୅Խֶ 5, No. 566, 18–21 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 3. ਓ޻‫ݩ‬ૉʯ, ‫ݱ‬୅Խֶ 6, No. 567, 44–48 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 4. ‫ݬ‬ͷ৽‫ݩ‬ૉʯ, ‫ݱ‬୅Խֶ 7, No. 568, 36–39 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 5. ௒ॏ‫ݩ‬ૉʯ, ‫ݱ‬୅Խֶ 8, No. 569, 40–43 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 6. ཧ‫ݚ‬ͷ৽‫ݩ‬ૉ୳ࡧ (1)ʯ, ‫ݱ‬୅Խֶ 9, No. 570, 24–28 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 7. ཧ‫ݚ‬ͷ৽‫ݩ‬ૉ୳ࡧ (2)ʯ, ‫ݱ‬୅Խֶ 10, No. 571, 53–57 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 8. ཧ‫ݚ‬ͷ৽‫ݩ‬ૉ୳ࡧ (3)ʯ, ‫ݱ‬୅Խֶ 11, No. 572, 25–28 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 9. ϩγΞͱถࠃʹΑΔ৽‫ݩ‬ૉ୳ࡧʯ, ‫ݱ‬୅Խֶ 12, No. 573, 52–56 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 10. χϗχ΢Ϝ໋໊ʯ, ‫ݱ‬୅Խֶ 1, No. 574, 44–49 (2019).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 11. ͞ΒͳΔ৽‫ݩ‬ૉΛ‫ٻ‬Ίͯʯ, ‫ݱ‬୅Խֶ 2, No. 575, 42–46 (2019).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 12. ৽‫ݩ‬ૉͷԽֶతੑ࣭ʯ, ‫ݱ‬୅Խֶ 3, No. 576, 42–46 (2019).
(Proceedings)
Y. Aritomo, N. Liyana, S. Tanaka, Y. Miyamoto, B. Yanagi, K. Hagino, T. Tanaka, K. Nishio, M. Ohta, “Estimation for synthesis ofsuperheavy elements,” JPS Conf. Proc. 23, 013001 1–4 (2018).

[Book](Original Paper)ࡩҪ߂, ࠜ໼ࡾ࿠, ࣉౢ޹ਔ, ࡫৿‫و‬༟, Ӌ৔޺ޫ, ʮ‫ݩ‬ૉ‫ݕ‬ఆ 2ʯ, Խֶಉਓ, 2018 ೥ 8 ݄ 20 ೔.

Oral Presentations[International Conference etc.]
H. Haba, “Production and applications of radioisotopes at RIKEN RI Beam Factory,” Seminar at Brookhaven National Laboratory, New
York, USA, May, 2018.
H. Haba, “Synthesis and chemistry of superheavy elements at RIKEN,” DAE-BRNS Eighth Biennial Symposium on Emerging Trends in
Separation Science and Technology (SESTEC-2018), Goa, India, May, 2018.
H. Haba, “Production and applications of radioisotopes at RIKEN RI Beam Factory,” Seminar at Inter-University Accelerator Centre,
New Delhi, India, May, 2018.
H. Haba, “Applications with unstable ion beams and complementary techniques at the RIKEN,” Consultancy Meeting on Novel Multidisciplinary Applications with Unstable Ion Beams and Complementary Techniques, Vienna, Austria, July, 2018.
H. Haba, “Present Status and perspectives of SHE researches at RIKEN,” IX International Symposium on Exotic Nuclei (EXON-2018),
Petrozavodsk, Russia, September, 2018.
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. X. Watanabe, H. Wollnik, S. Yamaki, “Direct mass measurements of heavy/superheavy nuclei with an MRTOF-MS coupled with the
GARIS-II,” The International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) 2018, Geneva, Switzerland, September, 2018.
M. Rosenbusch, Y. Ito, M. Wada, P. Schury, 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, A. Takamine, T. Tanaka,
Y. X. Watanabe, H. Wollnik, S. Yamaki, “Advances and future plans for nuclear mass measurements at RIKEN,” The International
Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) 2018, Geneva, Switzerland, September, 2018.
M. Mukai, Y. Hirayama, Y. X. Watanabe, P. Schury, 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, H. Miyatake, “Development of a multi-segmented proportional gas counter for
β-decay spectroscopy at KISS,” The International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) 2018,
Geneva, Switzerland, September, 2018.
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, K. Hagino, “Fusion dynamics for
hot fusion reactions revealed in quasielastic fusion barrier distributions,” JPS-APS Joint meeting on Nuclear Physics Division, Hawaii,
U.S.A., October, 2018.
H. Haba, “Production of radioisotopes for application studies at RIKEN RI Beam Factory,” 4th International Conference on Applicationof RadiotraCers and Energetic Beams in Sciences (ARCEBS-2018), Kolkata, India, November, 2018.
Y. Komori, H. Haba, T. Yokokita, S. Yano, N. Sato, K. Ghosh, Y. Sakemi, H. Kawamura, “Measurement of excitation functions of the
206/207/208
Pb(11 B, X)212 Fr reactions and complex formation studies of Fr with crown ethers,” 4th International Conference on Applicationof RadiotraCers and Energetic Beams in Sciences (ARCEBS-2018), Kolkata, India, November, 2018.
H. Haba, “Production and application of radioisotopes using He jet transport system at RIKEN RI Beam Factory,” Seminar at Variable
Energy Cyclotron Centre, Kolkata, India, November, 2018.
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, K. Hagino, “Fusion dynamics for
hot fusion reactions revealed in quasielastic fusion barrier distributions,” 13th International Conference on Nucleus-Nucleus Collisions,- 287 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Omiya, Japan, December, 2018.
H. Haba, “Production of radioisotopes for application studies at RIKEN RI Beam Factory,” Technical Meeting on Novel Multidisciplinary
Applications with Unstable Ion Beams and Complementary Techniques, Vienna, Austria, December, 2018.
Y. Komori, “Activities related to SHE target production and aqueous chemistry of SHEs at RIKEN,” NUSPRASEN Workshop on Superheavy element research, target techniques and related topics, GSI, Darmstadt, Germany, February, 2019.
H. Haba, “Present status and perspectives of SHE researches at RIKEN,” NUSPRASEN Workshop on Superheavy element research,target techniques and related topics and NUSTAR Annual Meeting 2019, Darmstadt, Germany, February, 2019.
T. Tanaka, “Fusion dynamics for hot fusion reactions revealed in quasielastic fusion barrier distributions,” 54th ASRC International
Workshop Sakura-2019 “Nuclear Fission and Structure of Exotic Nuclei,” Tokai, Japan, March, 2019.

[Domestic Conference]
H. Haba, “Present status and perspectives of superheavy element chemistry at RIKEN,” ‫ڀݚ‬ձʮ௒ॏ‫ݩ‬ૉ‫ڀݚ‬ͷ৽ల։ʯ, ෱Ԭࢢ, 2018
೥ 7 ݄.
ాதହ‫و‬, ʮ௒ॏ֩ྖҬͰͷ‫ܥ‬౷తͳ֩༥߹൓Ԡͷ‫ڀݚ‬ʯ‫ڀݚ‬ձ, ʮ௒ॏ‫ݩ‬ૉ‫ڀݚ‬ͷ৽ల։ʯ, ෱Ԭࢢ, 2018 ೥ 7 ݄.
Ӌ৔޺ޫ, ʮཧ‫͚͓ʹݚ‬Δ RI ੡଄Ԡ༻ʙ৽‫ݩ‬ૉͷԽֶ͔Β֩ҩֶͷ਍அɾ࣏ྍ·Ͱʙʯ, େࡕେֶ์ࣹઢՊ‫ج‬൫‫ൃߏػ‬଍‫ه‬೦γϯϙδ΢Ϝ, ๛தࢢ, 2018 ೥ 8 ݄.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, Ճ࣏େ࠸, M. Rosenbusch, ໦ଜ૑େ, ৿ຊ޾࢘, Ӌ৔޺ޫ, ੴᖒྙ, ৿ాߒհ, ‫ٶ‬෢Ӊ໵,
H. Wollnik, ʮMRTOF-MS ༻ͷ α-ToF ‫ݕ‬ग़‫ث‬ͷੑೳධՁʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫ࢢ౎ژ‬, 2018
೥ 9 ݄.
Ӌ৔޺ޫ, ʮ৽‫ݩ‬ૉχϗχ΢Ϝൃ‫΁ݟ‬ͷಓͷΓʯ, ୈ 5 ճ‫ح‬ੴത෺‫ؗ‬αΠΤϯεΧϑΣ, ෋࢜‫ࢢٶ‬, 2018 ೥ 10 ݄.
Ӌ৔޺ޫ, ʮཧ‫͚͓ʹݚ‬Δ RI ੡଄Ԡ༻ʙ৽‫ݩ‬ૉͷ୳ࡧ͔Β֩ҩֶͷ਍அɾ࣏ྍ·Ͱʙʯ, ์ࣹઢՊֶϫʔΫγϣοϓʮจཧ‫ڞ‬૑Λֵ৽͢ΔྔࢠϏʔϜՊֶʯ, จ‫۠ژ‬, 2019 ೥ 2 ݄.
Ӌ৔޺ޫ, ʮཧ‫ ݚ‬RI ϏʔϜϑΝΫτϦʔͰ੡଄͢ΔԠ༻‫༻ڀݚ‬ϥδΦΞΠιτʔϓʯ, ཧ‫ݚ‬γϯϙδ΢Ϝʮਫ਼ີ෢૷߅ମͷ߹੒ͱ‫ػ‬ೳධՁʯ, ઍ୅ా۠, 2019 ೥ 3 ݄.
ૣਫ༑༸, ௕ᖛ߂‫ق‬, খᖒ௚໵, అಯ, ‫݈ాݪ‬Ұ, ాத߳௡ੜ, ಺ࢁѪࢠ, ੨໦‫ູو‬, ിࢁԹ, ߴ‫ڮ‬ٛ࿕, Ӌ৔޺ޫ, େલએত, ञ‫ݟ‬ହ‫׮‬,ʮిࢠͷӬ‫ؾిٱ‬૒‫ࢠۃ‬Ϟʔϝϯτ୳ࡧ΁޲͚ͨϑϥϯγ΢Ϝ‫ࢠݪ‬ͷੜ੒ͱτϥοϓʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձʢ2019೥ʣ, ෱Ԭࢢ, 2019 ೥ 3 ݄.
Ӌ৔޺ޫ, ʮ৽‫ݩ‬ૉͷ߹੒ͱԽֶʯ, ୈ 37 ճྔࢠ‫ܥ‬෼ࢠՊֶηϛφʔ, ਆ‫ࢢށ‬, 2019 ೥ 3 ݄.
খ৿༗‫ࢠر‬, Ӌ৔޺ޫ, ԣ๺୎໵, ໼ೲ৻໵, ࠤ౻๬, Ghosh Kaustab, ञ‫ݟ‬ହ‫׮‬, ઒ଜ޿࿨, ʮ206/207/208 Pb(11 B, X)212 Fr ൓Ԡͷྭ‫਺ؔى‬ଌఆͱΫϥ΢ϯΤʔςϧΛ༻͍ͨ Fr ͷࡨ‫ܗ‬੒൓Ԡʯ, ೔ຊԽֶձୈ 99 य़‫ق‬೥ձ 2019, ਆ‫ࢢށ‬, 2019 ೥ 3 ݄.
ԣ๺୎໵, ּদྑਸ, খ৿༗‫ࢠر‬, ౉ᬒӯհ, ΰʔγϡίʔελϒ, Ԧ༸, ৿େً, ࣰ‫ްݪ‬, Ӌ৔޺ޫ, ʮRf ͷེࢎࡨମ‫͚ͨ޲ʹڀݚ‬όον‫ݻܕ‬ӷநग़૷ஔʹΑΔ Zr ‫ ͼٴ‬Hf ͷӄΠΦϯަ‫׵‬ʯ, ೔ຊԽֶձୈ 99 य़‫ق‬೥ձ 2019, ਆ‫ࢢށ‬, 2019 ೥ 3 ݄.
ೋ‫ٶ‬लඒ, ּদྑਸ, ଎ਫᠳ, Ӭ੉কߒ, ॏՏ༏େ, ۙ౻੒ඒ, ౉ᬒӯհ, Ӌ৔޺ޫ, ԣ๺୎໵, খ৿༗‫ࢠر‬, ৿େً, Ԧ༸, ΰʔγϡίʔελϒ, ࠤ౻๬, ࣰ‫ްݪ‬, ʮ102 ൪‫ݩ‬ૉ No ͷΞϯϞχΞਫ‫ͼٴ‬ਫࢎԽφτϦ΢Ϝਫ༹ӷதʹ͓͚ΔαϚϦ΢Ϝ‫ڞ‬௜‫ڍ‬ಈʯ, ೔ຊԽֶձୈ 99 य़‫ق‬೥ձ 2019, ਆ‫ࢢށ‬, 2019 ೥ 3 ݄.
ాதହ‫و‬, ʮ௒ॏ‫ݩ‬ૉؔ࿈ͷ૷ஔ։ൃʯ, ৽ֶज़ྖҬ‫ڀݚ‬ʮӉ஦‫؍‬ଌ‫ݕ‬ग़‫ࢠྔͱث‬ϏʔϜͷग़ձ͍ɻ৽ͨͳԠ༻΁ͷՍ͚‫ڮ‬ɻʯएखϋʔυ΢ΣΞ‫ڀݚ‬ձ, ๛தࢢ, 2019 ೥ 3 ݄.
T. Tanaka, “Study of barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis,” 10th Stop andSlow Radio Isotope (SSRI) Workshop, ෱Ԭࢢ, 2019 ೥ 3 ݄.

Posters Presentations[International Conference etc.]
T. Niwase, K. Fujita, Y. Yamano, K. Watanabe, D. Kaji, K. Morimoto, H. Haba, T. Hirano, S. Mitsuoka, K. Morita, “Measuremet of fusion
barrier distribution in 51 V + 208 Pb system,” 13th International Conference on Nucleus-Nucleus Collisions, Omiya, Japan, December
2018.

[Domestic Conference]ۙ౻੒ඒ, ּদྑਸ, Ӭ੉কߒ, ҆ా༐ً, ॏՏ༏େ, େ಺Ꮺً, ਆాߊॆ, ೋ‫ٶ‬लඒ, ౉ᬑӯհ, Ӌ৔޺ޫ, ‫ٱ‬อ໦༞ੜ, খ৿༗‫ࢠر‬, ԣ๺୎໵, ໼ೲ৻໵, ࠤ౻๬, ࣰ‫ްݪ‬, ʮRf ͷԘࢎ‫Ͱܥ‬ͷ༹ഔநग़‫ڍ‬ಈͷ༗‫༹ػ‬ഔґଘੑʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫ࢢ౎ژ‬, 2018 ೥ 9 ݄.
ଜ্Үే, ฏ઒‫ܒو‬, ಺౻Նथ, ࡔ‫ޱ‬૱ࢤ, ౻ా‫܇‬༟, ‫৻ڷ‬ଠ࿠, ଍ཱஐ, ాத੟ਉ, ాதହ‫و‬, ఉ੉‫ོڿ‬, ৿ຊ޾࢘, Ӌ৔޺ޫ, Ճ࣏େ࠸, അ৔ल஧, Pierre Brionnet, ໦ଜ૑େ, ञҪӳߦ, ৿ాߒհ, ʮ௒ॏ‫ݩ‬ૉࣝผͷͨΊͷσʔλղੳख๏ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ
74 ճ೥࣍େձ, ෱Ԭࢢ, 2019 ೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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. There are two gas-filled recoil ion
separators installed at RILAC experimental hall. One is GARIS that is designed for symmetric reaction such as cold-fusion reaction,and the other is newly developed GARIS-II and GARIS-III these separators were designed for an asymmetric reaction such as hotfusion reaction. New elements 278 113 were produced by 70 Zn + 209 Bi reaction using GARIS. Further the new element search Z > 118
are preparing by using GARIS-II and GARIS-III.

2. Major Research Subjects(1) Maintenance of GARIS, GARIS-II and development of new gas-filled recoil ion separator GARIS-III(2) Maintenance and development of detector and DAQ system for GARIS, GARIS-II and GARIS-III(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
sensitivity. The GARIS-II was moved RILAC facility to RRC facility, and new element serach program aiming to element 119 wasstarted using GARIS-II. New separator GARIS-III was developed and installed into the RILAC experimental hall. It will be readyfor operation in fiscal year 2020 after some commissioning works. We will also oﬀer user-support if a researcher wishes to use thedevices for his/her own research program.

Members
Team Leader
Kouji MORIMOTO
Research/Technical Scientists
Masaki FUJIMAKI (concurrent: Super Technical Scientist
Beam Dynamics & Diagnostics Team)

Daiya KAJI (Technical Scientist)

Postdoctoral Researchers
Sota KIMURA

Pierre BRIONNET

Junior Research Associates
Satoshi ISHIZAWA (Yamagata Univ.)

Toshitaka NIWASE (Kyushu Univ.)

Visiting Scientists
Fuyuki TOKANAI (Yamagata Univ.)
Yuta ITO (JAEA)
Eiji IDEGUCHI (Osaka Univ. RCNP)

Shinichi GOTO (Niigata Univ.)
Katsuhisa NISHIO (JAEA)

Student Trainees
Yoshiki TAKAHASHI (Niigata Univ.)
Keigo BANDO(Kyushu Univ.)
Hayato NUMAKURA (Yamagata Univ.)

Takao SAITO (Kyushu Univ.)
Hikaru HIROSE (Niigata Univ.)
Kenta MANABE (Kyushu Univ.)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
S. Kimura, Y. Ito, D. Kaji, P. Schury, M. Wada, H. Haba, T. Hashimoto, Y. Hirayama, M. MacCormick, H. Miyatake, J. Y. Moon,
K. Morimoto, M. Mukai, I. Murray, A. Ozawa, M. Rosenbusch, H. Schatz, A. Takamine, T. Tanaka, Y. X. Watanabe, H. Wollnik,“Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-offlight mass spectrograph, “ Int. J. Mass Spectrom. 430, 134–142 (2018).

[࿨จ]৿ຊ޾࢘, ʮ৽‫ݩ‬ૉχϗχ΢Ϝ͸͍͔ʹͯ͠ൃ‫͞ݟ‬Εͨͷ͔ʯ, ෺ཧ‫ڭ‬ҭୈ 66 ‫ר‬ୈ 4 ߸ʢ2018ʣ, p. 278.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, ໦ଜ૑େ, M. Rosenbusch, Ճ࣏େ࠸, ৿ຊ޾࢘, Ӌ৔޺ޫ, ࢁ໦͞΍͔, ాதହ‫و‬, ৿ాߒհ,ߴๆѪࢠ, ‫ٶ‬෢޺໵, ฏࢁլҰ, ౉ᬒ༟, J. Y. MOON, ޲Ҫ΋΋, H. Wollnik, ʮMRTOF-MS ༻ͷ α-ToF ‫ݕ‬ग़‫ث‬ͷੑೳධՁʯ, ์ࣹԽֶ ୈ 39 ߸ 2019 ೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Oral Presentations[International Conference etc.]
K. Morimoto, “Superheavy element research at RIKEN,” 13th International Conference on Nucleus-Nucleus Collisions (NN2018),
Ohmiya, Saitama, Japan, December 5, 2018.
S. Kimura, “Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via MRTOF- MS,”
Fifth joint meeting of the nuclear physics divisions of the APS and the JPS, Hawaii, USA, 2018.
T. Niwase, M. Wada, P. Schury, Y. Ito, D. Kaji, M. Rosenbusch, S. Kimura, K. Morimoto, H. Haba, S. Ishizawa, K. Morita, H. Miyatake,
H. Wollnik, “Development of α-ToF detector for correlation measurement of atomic masses and decay properties,” 5th Joint Meetingof the APS Division of Nuclear Physics and the Physical Society of Japan, October 27, 2018.
T. Niwase, K. Fujita, Y. Yamano, K. Watanabe, D. Kaji, K. Morimoto, H. Haba, T. Hirano, S. Mitsuoka, K. Morita, “Measurement offusion barrier distribution in 51 V + 208 Pb system,” Nucleus-Nucleus Collisions (NN2018), December 5, 2018.

[Domestic Conference]
D. Kaji, S. Mitsuoka, G. Hirano, T. Niwase, K. Morimoto, ʮX ઢ‫؍‬ଌʹΑΔ௒ॏ֩ͷ‫ࢠݪ‬൪߸௚઀ಉఆʹ޲͚ͨ Si-Ge ‫ݕ‬ग़‫ث‬ΞϨΠͷ։ൃʯ, ೔ຊ์ࣹԽֶձୈ 62 ճ౼࿦ձ, ‫౎ژ‬େֶ, ‫౎ژ‬, 2018 ೥ 9 ݄.
T. Niwase, ʮ௒ॏ࣭֩ྔ෼ੳ΁޲͚ͨ α-ToF ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ௒ॏ‫ݩ‬ૉ‫ڀݚ‬ͷ৽ల։, ‫۝‬भେֶ, ෱Ԭ, 2018 ೥ 7 ݄ 31 ೔.
T. Niwase, M. Wada, P. Schury, Y. Ito, S. Kimura, M. Rosenbusch, D. Kaji, K. Morimoto, H. Haba, S. Yamaki, T. Tanaka, K. Morita,
A. Takamine, H. Miyatake, Y. Hirayama, Y. Watanabe, J. Y. Moon, M. Mukai, H. Wollnik, ʮMRTOF-MS ༻ͷ α-ToF ‫ݕ‬ग़‫ث‬ͷੑೳධՁʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձ ୈ 62 ճ์ࣹԽֶ౼࿦ձ, 2018 ೥ 9 ݄.
T. Niwase, ʮ௒ॏ֩ਫ਼ີ෼ੳ΁޲͚ͨ α-ToF ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ֩σʔλͱॏ‫ݩ‬ૉ߹੒Λத৺ͱ͢ΔӉ஦֩෺ཧ‫ڀݚ‬ձ, ๺ւಓେֶ,ࡳຈ, 2019 ೥ 3 ݄.
T. Niwase, D. Kaji, K. Morimoto, nSHE collaboration, ʮ௒ॏ֩߹੒࣮‫ݧ‬ͷͨΊͷ Si ‫ݕ‬ग़‫ ث‬box ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ 2019 ೥ 3 ݄.
T. Niwase, ʮα-ToF ‫ݕ‬ग़‫ث‬ͷ։ൃͱ 207 Ra ͷ࣭ྔ-่յಛੑଌఆʯ, ୈ 10 ճఀࢭɾ௿଎ RI ϏʔϜΛ༻͍ͨ֩෼ޫ‫ڀݚ‬ձ, 2019 ೥ 3 ݄.

[Others]
৿ຊ޾࢘, ʮ৽‫ݩ‬ૉχϗχ΢Ϝͷൃ‫ͱݟ‬, ͞ΒͳΔ௅ઓʯ, ೔ຊ෺ཧֶձެ։ߨ࠲, ౦‫ژ‬େֶຊ‫ڷ‬Ωϟϯύε, 2018 ೥ 11 ݄ 17 ೔.
৿ຊ޾࢘, ʮ৽‫ݩ‬ૉʮχϗχ΢Ϝʯͷൃ‫ޙࠓͱݟ‬ͷల։ʯ, ߕೆେֶϓϨϛΞ 4thʮ‫ݩ‬ૉͷ‫ؔ͢ʹݯى‬Δ୳‫ڀ‬ϓϩδΣΫτʯ, ߕೆେֶߕ༑ձ‫ؗ‬, 2019 ೥ 3 ݄ 21 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Nuclear Science and Transmutation Research Division
Astro-Glaciology Research Group
1. Summary of Research Activity

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, climate science, and glaciology.
On the experimental side, we analyze ice cores drilled at the Dome Fuji station, in Antarctica, in collaboration with the National
Institute of Polar Research (NIPR, Tokyo). These ice cores are time capsules, which preserve atmospheric information of the past.
In particular, ice cores obtained around the Dome Fuji station are known to be unique because they contain much more informationon conditions in the stratosphere. This means that there are significant advantages in using Dome Fuji ice cores if we wish to study
the universe, since gamma-rays and high-energy protons that are emitted in certain astronomical processes aﬀect the chemical andisotopic compositions in the stratosphere. Our principal aim is to acquire and interpret information preserved in ice cores regarding:• Signatures of past solar cycles and volcanic eruptions;• Relationships between climate change and solar activity;• Traces of past supernova explosions in our galaxy, in order to understand better the rate of galactic supernova explosions.

Moreover, we are promoting the projects on:• Development of precise analytical techniques and instrumentation of high-sensitivity and high-temporal resolution;• The evolution of molecules in space;• The application of our high-sensitivity method of isotopic analysis to archaeological artifacts.

On the theoretical side, we are simulating numerically:• Changes in the chemical composition of the stratosphere induced by gamma-rays and/or high-energy particles emitted from
explosive astronomical phenomena, such as galactic supernovae and solar proton events; and• The explosive nucleosynthesis (including the r-process, the rapid neutron capture process, which creates elements heavier
than iron) that arises in the environment of core-collapse supernova explosions.
It is noteworthy that the as yet not fully understood frequency of supernova explosions in our galaxy is crucial to an understandingof the r-process nucleosynthesis. These all will contribute to understanding relationships between the universe and earth, to advancethe Astro-Glaciology to Astro-Terrestrial Science.

Members
Group Director
Yuko MOTIZUKI
Research/Technical Scientists
Kazuya TAKAHASHI (Senior Research Scientist)

Yoichi NAKAI (Senior Research Scientist)

Senior Visiting Scientist
Yasushige YANO
Visiting Scientists
Hideharu AKIYOSHI (Nat ‘l Inst. for Environ. Studies)
Hideki MADOKORO (Mitsubishi Heavy Ind., Ltd.)

Akira HORI (Kitami Inst. of Tech.)
Kenji TANABE (Okayama Univ. of Sci.)

AssistantKeiko SUZUKI
Part-time Worker
Satomi NEGISHI

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
C. L. Fryer, F. Timmes, A. L. Hungerford, A. Couture, Y. Motizuki et al., “Catching Element Formation In The Act—The Case for a New
MeV Gamma-Ray Mission: Radionuclide Astronomy in the 2020s,” A White Paper submitted to the 2020 Decadal Survey, (USA, Feb.
2019).
F. Miyake, K. Horiuchi, Y. Motizuki, Y. Nakai, K. Takahashi, K. Masuda, H. Motoyama, H. Matsuzaki, “10 Be signature of the cosmic
ray event in the 10th century CE in both hemispheres, as confirmed by quasi-annual 10 Be data from the Antarctic Dome Fuji ice core,”
Geophys. Res. Lett. 46, 11–18 (2019). *- 291 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

K. Takahashi, Y. Nakai, Y. Motizuki, T. Ino, S. Ito, S. B. Ohkubo, T. Minami, Y. Takaku, Y. Yamaguchi, M. Tanaka, H. Motoyama, “Highsensitivity sulfur isotopic measurements for Antarctic ice core analyses,” Rapid Communications in Mass Spectrom. 32, 1991–1998(2018). *E. Tsantini, T. Minami, K. Takahashi, M. A. C. Ontiveros, “Analysis of sulfur isotopes to identify the origin of cinnabar in the Roman
wall paintings from Badalona (Spain),” J. Archaeol. Sci. Rep. 18, 300–307 (2018). *[Annals](Original Papers) *Subject to Peer Review
Տ໺ຎ໹, ߴ‫ڮ‬࿨໵, ࠓ௡અੜ, ೆ෢ࢤ, ʮ෱Ԭ‫҆ݝ‬ಙ୆Ҩ੻‫͚͓ʹ܈‬Δगͷ࢖͍෼͚ʹ͍ͭͯʯ, ‫ݹ‬୅, 142, 97–103 (2018).*[Book](Original Papers) *Subject to Peer Review
தҪཅҰ, ʰՃ଎‫ث‬ϋϯυϒοΫʱ (‫ڞ‬ಉࣥච), ೔ຊՃ଎‫ֶث‬ձฤ, pp. 533–533ʢʮେ‫ؾ‬ඍཻࢠͱۜՏӉ஦ઢʯʣ, ‫ؙ‬ળग़൛, (2018). *Oral Presentations[International Conference etc.]
Y. Motizuki (Invited talk), “Relationship between temperature proxy and solar activity studied with a Dome Fuji (Antarctica) shallow ice
core,” PSTEP A04 International Workshop: Impact of solar activity variations on surface climate via several pathways, Kyoto, February
19–20, 2019.
Y. Motizuki, K. Takahashi,Y. Nakai, H. Motoyama, K. Kodera, “New annually-resolved water isotope data of the past 2000 years from a
Dome-Fuji shallow ice core,” CLIVASH2k workshop, Cambridge, UK, September 4–5, 2018.
Y. Nakai, N. Watanabe, Y. Oba, “Laboratory experiment for hydrogenation of C60 fullerenes deposited on a solid surface under low
temperature conditions,” The Olympian Symposium 2018 on “Gas and stars from milli- to mega- parsecs,” Paralia Katerini, Greece,
May 31, 2018.

[Domestic Conference]๬݄༏ࢠʢট଴ߨԋʣ, ʮೆ‫ۃ‬ͷණ͔Βͻ΋ͱ͘Ӊ஦ͱ஍‫ٿ‬ͷྺ࢙ʯ, ਔՊ‫ه‬೦ߨԋձʮΞΠιτʔϓͰ୳ΔӉ஦ʯ, ެӹࡒஂ๏ਓਔ
Պ‫ه‬೦ࡒஂ, ੢౦‫ژ‬, 2018 ೥ 11 ݄ 11 ೔.
๬݄༏ࢠʢট଴ߨԋʣ, ʮςϥɾΞετϩϊϛʔ—Ӊ஦ͱ஍‫ٿ‬Λ݁Ϳ෺ཧՊֶ—ʯ, ࡛‫ۄ‬େֶཧֶ෦෺ཧྔࢠྗֶಛผߨٛ, ͍ͨ͞·,2019 ೥ 1 ݄ 7 ೔.
தҪཅҰ, ౉෦௚थ, ʮ௿Թബບঢ় C60 ‫ݻ‬ମʹτϥοϓ͞Εͨਫૉ෼ࢠͷৼಈճసྭ‫ى‬ͷ੺֎‫ٵ‬ऩε΃Ϋτϧʯ, ‫ࢠݪ‬িಥֶձୈ 43
ճ೥ձ, ‫౎ژ‬, 2018 ೥ 10 ݄ 13 ೔.
ߴ‫ڮ‬࿨໵, தҪཅҰ, ๬݄༏ࢠ, Ҫ໺හߦ, ҏ౻ໜ, େ‫ٱ‬อஐ, ߴ‫ٱ‬༤Ұ, ࢁ‫ޱ‬ٛଚ, ాதඒึ, ຊࢁल໌, ʮೆ‫ۃ‬ණচίΞͷৄࡉղੳΛ‫ݟ‬ਾེ͑ͨԫಉҐମൺ෼ੳͷߴ‫౓ײ‬ԽͷࢼΈʯ, ೔ຊ෼ੳԽֶձୈ 67 ճ೥ձ, ઋ୆, 2018 ೥ 9 ݄ 12–14 ೔.
ೆ෢ࢤ, ߴ‫ڮ‬࿨໵, ʮ௒ඍྔེԫಉҐମ෼ੳ๏ͷ։ൃͱߟ‫ࢿֶݹ‬ྉ෼ੳͷར఺ʯ, ೔ຊจԽࡒՊֶձୈ 35 ճେձ, ಸྑ, 2018 ೥ 7 ݄ 7೔.
ࡾ୐ෙࠫ, ງ಺Ұึ, ᓎҪ‫ٱܟ‬, ૿ాެ໌, ຊࢁल໌, দ࡚ߒ೭, ๬݄༏ࢠ, ߴ‫ڮ‬࿨໵, தҪཅҰ, ʮυʔϜ;͡ΞΠείΞͷ 10 Be ෼ੳʹΑΔ୯೥Ӊ஦ઢΠϕϯτͷௐࠪ IIʯ, “Research of annual cosmic ray events using 10 Be in the Dome Fuji ice core II,” ೔ຊ஍‫ٿ‬࿭੕Պֶ࿈߹ 2018 ೥࿈߹େձ, ઍ༿, 2018 ೥ 5 ݄ 20–24 ೔.
ࡾ୐ෙࠫ, ງ಺Ұึ, ๬݄༏ࢠ, தҪཅҰ, ߴ‫ڮ‬࿨໵, ૿ాެ໌, ຊࢁल໌, দ࡚ߒ೭, ʮυʔϜ;͡ΞΠείΞͷҰ೥෼ղೳ 10 Be σʔλʹΈΒΕΔ AD993/994 Ӊ஦Πϕϯτʯ, ୈ 21 ճ AMS γϯϙδ΢Ϝ , ౦‫ژ‬, 2018 ೥ 12 ݄ 17–18 ೔.
ࡾ୐ෙࠫ, ງ಺Ұึ, ๬݄༏ࢠ, தҪཅҰ, ߴ‫ڮ‬࿨໵, ૿ాެ໌, ຊࢁल໌, দ࡚ߒ೭, ʮ໿୯೥෼ղೳ 10 Be σʔλΛ༻͍ͨ 994 ೥Ӊ஦ઢΠϕϯτͷௐࠪʯ, υʔϜ;͡ΞΠείΞίϯιʔγΞϜ೥࣍‫ूڀݚ‬ձ, ཱ઒, 2019 ೥ 3 ݄ 27–28 ೔.
ੁᖒՂੈ, ࡾ୐ෙࠫ, ງ಺Ұึ, ࡫ެ࿨, ๬݄༏ࢠ, ߴ‫ڮ‬࿨໵, தҪཅҰ, ຊࢁल໌, দ࡚ߒ೭, ʮυʔϜ;͡ΞΠείΞத 10 Be ͱ 36 Clͷߴ෼ղೳଌఆʹΑΔ BC5480 ೥Ӊ஦ઢΠϕϯτͷௐࠪʯ, υʔϜ;͡ΞΠείΞίϯιʔγΞϜ೥࣍‫ूڀݚ‬ձ, ཱ઒, 2019 ೥ 3
݄ 27–28 ೔.

Posters Presentations[International Conference etc.]
Y. Motizuki, K. Takahashi, Y. Nakai, S. Wada, K. Horiuchi, F. Miyake, H. Motoyama, H. Akiyoshi, T. Imamura, K. Kodera, “TerraAstronomy/multi-disciplinary studies with Antarctic Ice cores and Numerical Simulations,” The Ninth International Symposium on
Polar Science, Tachikawa, December 4–7, 2018.
Y. Nakai, N. Watanabe, Y. Oba, “Hydrogenation of C60 deposited on a substrate under low temperature condition,” The 30th International
Conference on Photonic, Electronic and Atomic Collisions, Cairns Australia, August 2017.
K. Takahashi, “New method for comprehensive detection of trace elements in environmental or biochemical materials using an electroncyclotron-resonance ion-source mass spectrometer,” the 4th World Congress on Mass Spectrometry, London, UK, June 2017.

Press Release
K. Takahashi, Y. Nakai, Y. Motizuki, T. Ino, S. Ito, Satoru B. Ohkubo, T. Minami, Y. Takaku, Y. Yamaguchi, M. Tanaka, H. Motoyama,“Signature of the large volcanic eruption in AD1883 detected by new high-sensitivity sulfur isotopic measurement method applied toan Antarctic ice core,” The Japan Society for Analytical Chemistry, Tokyo, Aug. 31, 2018, for a presentation at the 67th annual meetingof the Japan Society for Analytical Chemistry, Sendai, September 12–14, 2018.

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Paper information, “High-sensitivity sulfur isotopic measurements for Antarctic ice core analyses,” Rapid Communications in Mass
Spectrometry 32, 1991–1998 (2018).
K. Takahashi, “Mass spectrometry tracks tiny amounts of sulfur in Antarctic ice cores—An advanced isotope-measuring system can reveal
insights about past environments in shorter time frames,” Research Highlight, RIKEN RESEARCH, SUMMER, 2019,11. 2019.
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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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.

Members
Group Director
Hiroyoshi SAKURAI (concurrent: Director, RI Physics Lab.)
AssistantIzumi YOSHIDA

Asako TAKAHASHI

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
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. 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).

[Proceedings]
H. Sakurai, H. Okuno, N. Sakamoto, Y. Mori, T. Matsuzaki, M. Fukuda, R. Fujita, M. Kawashima, “Reduction and resource recyclingof high-level radioactive wastes through nuclear transmutations—(5) Accelerator transmutation system and related developments forelement technologies—,” Proceedings of Fifteenth NEA Information Exchange Meeting on Actinide and Fission Product Partitioning
and Transmutation.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Oral Presentations[International Conference etc.]
H. Sakurai (invited), “New steps reaching the horizon,” ImPACT International Symposium on “New Horizons of Partitioning and Transmutation Technologies with Accelerator System,” Tokyo, Japan, December, 2018.
H. Sakurai et al., “Nuclear reaction study for high-level radioactive waste: Cross section measurements for proton- and deuteron-induced
spallation of long-lived fission products,” The 10th China-Japan Joint Nuclear Physics Symposium, Huizhou, China, November, 2018.

[Domestic Conference]ᓎҪതّ, ʮ֩ม‫ʹ׵‬ΑΔߴϨϕϧ์ࣹੑഇ‫غ‬෺ͷେ෯ͳ௿‫ݮ‬ɾࢿ‫ݯ‬Խ (6-2) ImPACT Ճ଎‫ ث‬2017 Ϟσϧͷਐలʯ, ೔ຊ‫ֶྗࢠݪ‬ձ, ਫ‫ށ‬, 2019 ೥ 3 ݄ 21 ೔.
ᓎҪതّ, ʮՃ଎‫ث‬ɿ֩ม‫׵‬Λ࣮༻Խ͢Δֵ৽తՃ଎‫ث‬ʯ, ImPACT ެ։੒Ռใࠂձ, ౦‫ژ‬, 2019 ೥ 3 ݄ 9 ೔.

Posters Presentations[International Conference etc.]
H. Sakurai, H. Okuno, N. Sakamoto, Y. Mori, T. Matsuzaki, M. Fukuda, R. Fujita, M. Kawashima, “Reduction and resource recycling of
high-level radioactive wastes through nuclear transmutations—(5) Accelerator transmutation system and related developments for element technologies—,” Fifteenth NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation,
OECE/NEA, 1st , Manchester, UK, October, 2018.

[Domestic Conference]ᓎҪതّ, ʮγεςϜධՁʯ, ImPACT ެ։੒Ռใࠂձ, ౦‫ژ‬, 2019 ೥ 3 ݄ 9 ೔.

Awardsେ௡ल‫ڿ‬, ౻ాྰࢠ, দ࡚ఓࢢ࿠, ᓎҪതّ, ԼӜ‫ڗ‬, ਫ‫࢘ߒޱ‬, େҪ઒޺೭, খᖒਖ਼‫ج‬, ਔҪాߒೋ, 21 ੈ‫໌ൃل‬৆, ެӹࣾஂ๏ਓൃ
໌‫ڠ‬ձ, 2018 ೥ 6 ݄ 12 ೔.

Press Release೔‫৽ܦ‬ฉ, ֩ഇ‫غ‬෺ʮม‫׵‬ʯʹ‫׆‬࿏, ઌ୺ٕज़, 2018 ೥ 7 ݄ 29 ೔, ೔‫ ץ‬30 ໘.
ಡച৽ฉ, ʮ֩ͷ͜Έʯ͔Β‫ر‬গۚଐ, 2019 ೥ 2 ݄ 17 ೔, ೔‫ ץ‬31 ໘.

Outreach ActivitiesᓎҪതّ, ʮ֩ม‫ࣹ์—׵‬ੑ෺࣭Λߴޮ཰Ͱ୹ण໋ɾແ֐Խ͢Δʯ, ୈ 34 ճʮ੢‫ٶ‬αΠΤϯεஊ࿩ձʯ, ߕೆେֶ੢‫ٶ‬Ωϟϯύεɾ੢‫ٶ‬αΠΤϯεஊ࿩ձʢߕೆେֶϚωδϝϯτ૑଄ֶ෦ʣ, 2018 ೥ 7 ݄ 28 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 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 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 collaboration hub on many groups which plan to take data using fast RI beam in RIBF facility.
Concentrating on take 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)Technical Staﬀ I
Nobuyuki CHIGA
Contract Researcher
He WANG
Visiting Scientists
Takashi TERANISHI (Kyushu Univ.)

Satoshi TAKEUCHI (Tokyo Tech)Student Trainees
Keita NAKANO (Kyushu Univ.)
Kenji NISHIZUKA (Niigata Univ.)
Ayaka IKEDA (Niigata Univ.)
Junki SUWA (Kyushu Univ.)

Kazuya CHIKAATO (Niigata Univ.)
Kotaro IRIBE (Kyushu Univ.)
Hiroya YOSHIDA (Kyushu Univ.)

List of Publications & Presentations
Publications[Proceedings]
X. Sun, H. Wang, H. Otsu, H. Sakurai et al., “Reaction study of 136 Xe on proton, deuteron and carbon at 168A MeV,” Proceedings of the
15th International Conference on Nuclear Reaction Mechanisms, CERN-Proceedings-2019-001 (CERN, Geneva, 2019), pp. 153–157.

Oral Presentations[International Conference etc.]
H. Otsu, “Direct measurement of proton and deuteron induced reaction cross sections on long lived fission products using inverse kinematics,” Technical Meeting on Novel Multidisciplinary Applications with Unstable Ion Beams and Complementary Techniques, IAEA
Headquarters, Vienna, Austria, December, 2018.
H. Wang et al., “Nuclear reaction study for long-lived fission products in high-level radioactive waste: Cross section measurements for
proton- and deuteron-induced spallation reactions,” 13th International Conference on Nucleus-Nucleus Collisions (NN2018), Omiya,
Saitama, Japan, December 4–8, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

H. Sakurai, H. Wang et al., “Spallation reaction study for fission products in nuclear waste: Cross section measurements for 107 Pd,
137
Cs, 136 Xe, and 90 Sr on proton and deuteron at diﬀerent reaction energies,” the 10th China-Japan Joint Nuclear Physics Symposium,
Huizhou, China, November 18–23, 2018.
H. Wang et al., “Spallation reaction study for fission products in nuclear waste: Cross section measurements for 107 Pd, 137 Cs, 136 Xe, and90
Sr on proton and deuteron at diﬀerent reaction energies,” Fifteenth NEA Information Exchange Meeting on Actinide and Fission
Product Partitioning and Transmutation, Manchester Hall, Manchester, UK, September 30 October 3, 2018.
H. Wang et al., “Nuclear reaction study for high-level radioactive waste: Cross section measurements for proton- and deuteron-induced
spallation reactions of long-lived fission products,” The 15th edition of the Varenna Conference on Nuclear Reaction Mechanisms(NRM), Varenna, Italy, June 11–15, 2018.

[Domestic Conference]෢಺૱ ଞ 6 ໊, ImPACT-RIBF Collaboration, ʮΫʔϩϯ෼ղ൓ԠʹΑΔ 79, 80 Se ͓Αͼ 93, 94 Zr ͷޫ‫ٵ‬ऩஅ໘ੵಋग़ʯ, ೔ຊ෺ཧֶձ
ୈ 73 ճ೥࣍େձ, ໺ా, 2018 ೥ 3 ݄.
ಓਖ਼৽Ұ࿠ ଞ 8 ໊, ImPACT-RIBF Collaboration, ʮOEDO ϏʔϜϥΠϯͷ։ൃ͓Αͼ 2017 ೥౓࣮‫ݧ‬ʯ, ೔ຊ‫ֶྗࢠݪ‬ձ೥ձ, େࡕ,2018 ೥ 3 ݄.
ಊԂণഢ ଞ 8 ໊, ImPACT-RIBF Collaboration, ʮ௿଎ RI ϏʔϜΛ༻͍ͨ 107 Pd, 93 Zr ͷཅࢠ͓Αͼॏཅࢠ༠‫ى‬൓Ԡଌఆʯ, ೔ຊ‫ࢠݪ‬ྗֶձ೥ձ, େࡕ, 2018 ೥ 3 ݄.
෢಺૱ ଞ 5 ໊, ʮ79, 80 Se ͓Αͼ, 93, 94 Zr ͷΫʔϩϯ෼ղ൓Ԡஅ໘ੵͷ౷‫่ܭ‬յϞσϧΛ࢖ͬͨղੳʯ, ೔ຊ‫ֶྗࢠݪ‬ձ೥ձ, େࡕ,2018 ೥ 3 ݄.
ਡ๚७‫ و‬ଞ 9 ໊, ʮY, Zr, Nb ಉҐମʹର͢Δ 100 MeV/nucleon ཅࢠɾॏཅࢠೖࣹ൓ԠͷಉҐମੜ੒அ໘ੵଌఆʯ, ೔ຊ‫ֶྗࢠݪ‬ձ೥ձ, େࡕ, 2018 ೥ 3 ݄.
ઍլ৴޾, ʮ௿ΤωϧΪʔதॏ֩༻ΠΦϯνΣϯόʔͷઃ‫ܭ‬ɾ੡࡞ʯ, ฏ੒ 29 ೥౓֩༥߹Պֶ‫ٕॴڀݚ‬ज़‫ڀݚ‬ձ, ‫ذ‬ෞ, 2018 ೥ 3 ݄.

Posters Presentations[International Conference etc.]
X. Sun et al., “Isotopic cross sections of proton-, deuteron- and carbon-induced reactions on 136 Xe,” 13th International Conference on
Nucleus-Nucleus Collisions, Omiya, Japan, December 4–8, 2018.

[Domestic Conference]ࡾ໦੖ྤ, ʮ238 U ͷඈߦ֩෼྾൓Ԡʹ͓͚Δ௿଎ 107 Pd ͓Αͼ 77 Se ͷΞΠιϚʔൺͷଌఆʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ, ໺ా,2018 ೥ 3 ݄.

Awardsத໺‫ܟ‬ଠ, ʮ௕ण໋֩෼྾ੜ੒෺ Zr-93 ͷ୹ण໋Խɾ࠶ࢿ‫ݯ‬Խʹ޲͚ͨ֩൓Ԡσʔλଌఆʯ, ‫۝‬भେֶΤωϧΪʔ΢ΟʔΫ 2018 ༏ल৆Press Release
H. Otsu, T. Matsuzaki, H. Sakurai, Jointly awarded “the 21st Century Invention Prize” for their research on Radioactive waste processing
method, Joint PR released with Toshiba Co, Toshiba Energy Systems & Solutions Corporation, JAEA, JST, Director General for Scienceand Technology and Innovation on the research, May 17, 2018.

Outreach Activities
Lecture of contents related to the 21st Century Invention Prize in the presense of Prince Hitachinomiya Masahito, Prince Hitachi House,
Aoyama, Tokyo June 1, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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.

MemberTeam Leader
Toshiyuki SUMIKAMA

List of Publications & Presentations
Oral Presentations[International Conference etc.]
T. Sumikama et al., “New control method of slowed-down RI beam and new PID method of secondary-reaction fragments at RIKEN RI
beam factory,” International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS XVIII), Geneva, Switzerland, September 16–21, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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.
We have established the muon in-beam spectroscopy method employing the “Seamine” spectrometer. The neutron data analysis- 299 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)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[Journal](Original Papers) *Subject to Peer Review
D. Hatakeyama, K. Nishimura, K. Matsuda, T. Namiki, Seungwon Lee, N. Nunomura, T. Aida, T. Matsuzaki, R. Holmestad, S. Wenner,
C. D. Marioara, “Eﬀect of copper addition on the cluster formation behavior of Al-Mg-Si, Al-Zn-Mg, and Al-Mg-Ge in the natural
aging,” METALLURGICAL AND MATERIALS TRANSACTIONS A V49A, (2018) p. 5871.

Oral Presentations[International Conference etc.]
T. Matsuzaki, H. Sakurai, “A new production method of 99 Mo by muon nuclear transmutation,” International Symposium on Technetium
and Rhenium, Science and Utilization, Moscow, Russia, October 2018.

[Domestic Conference]ࡈ౻ַࢤ, ৽૔५, ᓎҪതّ, দ࡚ఓࢢ࿠, ଞ, ʮϛϡʔΦϯ‫ ࢠݪ‬X ઢΛ༻͍ͨ Pd ಉҐମͷ֩ՙి൒‫ܘ‬ͷଌఆʯ, ೔ຊ෺ཧֶձ 73 ճ೥࣍େձ, ౦‫ژ‬ཧՊେֶ໺ాΩϟϯύε, ໺ా, 2018 ೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)ࡈ౻ַࢤ, ৽૔५, দ࡚ఓࢢ࿠, ᓎҪതّ, ଞ, “Study for the muon capture on palladium isotopes via neutron measurement,” ୈ 5 ճ೔ถ෺ཧֶձ ߹ಉ֩෺ཧ෼Պձ, ϋϫΠ ถࠃ, 2018 ೥ 10 ݄.
৽૔५, ࡈ౻ַࢤ, দ࡚ఓࢢ࿠, ᓎҪതّ, ଞ, ʮϛϡʔΦϯั֫ʹΑΔ Pd ಉҐମͷ֩ม‫׵‬ʯ, ೔ຊ෺ཧֶձ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
ࡈ౻ַࢤ, ৽૔५, দ࡚ఓࢢ࿠, ᓎҪതّ, ଞ, ʮύϥδ΢ϜͷϛϡʔΦϯั֫ʹ൐͏์ग़தੑࢠͷ௚઀ଌఆʯ, ೔ຊ෺ཧֶձ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
ࡾ໦‫ݠ‬ೋ࿠, ञҪେี, ্ࡔ༑༸, Ӊ௡৓༤େ, ञҪӳߦ, ࡫໺‫لڡ‬, ؔ‫ޱ‬ਔࢠ, দ࡚ఓࢢ࿠, ʮRIBF ʹ͓͚Δ 3 H(t, 3 He)3n ൓Ԡଌఆͷҝͷࡾॏਫૉඪత։ൃʯ, ೔ຊ෺ཧֶձ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
৽૔५, ࡈ౻ַࢤ, দ࡚ఓࢢ࿠, ᓎҪതّ, ʮϛϡΦϯ‫֫ั֩ࢠݪ‬൓ԠʹΑΔ֩ม‫׵‬ʯ, ೔ຊ‫ֶྗࢠݪ‬ձय़ͷ೥ձ, ҵ৓େֶ, ਫ‫ށ‬, 2019
೥ 3 ݄.

Awardେ௡ल‫ڿ‬, ౻ాྰࢠ, দ࡚ఓࢢ࿠, ᓎҪതّ, ԼӜ‫ڗ‬, ਫ‫࢘ߒޱ‬, େҪ઒޺೭, খᖒਖ਼‫ج‬, ਔҪాߒೋ, ฏ੒ 30 ೥౓શࠃൃ໌දজʮ21ੈ‫໌ൃل‬৆ʯ, ʮ์ࣹੑഇ‫غ‬෺ͷॲཧํ๏ͷൃ໌ʯ, ʢಛ‫ڐ‬ୈ 6106892 ߸ʣ, 2018 ೥ 6 ݄.

Patentদ࡚ఓࢢ࿠, ᓎҪതّ, ʮϛϡΦϯরࣹʹΑΔ์ࣹੑ෺࣭ͷ੡଄ํ๏͓Αͼͦͷ੡଄෺࣭ʯ, ಛ‫ ڐ‬PCT ग़‫ئ‬ʢ೔ຊ, ΞϝϦΧ, Χφ
μ, Ϥʔϩούʣ, ʢࠃࡍग़‫ئ‬൪߸ PCT/JP2017/003226ʣ, (2018 ೥ 8 ݄).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Nuclear Science and Transmutation Research Division
High-Intensity Accelerator R&D Group
1. Abstract

The R&D group, consisting of two teams, develops elemental technology of high-power accelerators and 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.
We gained a lot of experiences in these R&Ds. Among them, the development of a superconducting rf cavity has become thebasis 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)- 302 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 (concurrent: Cyclotron Team)
Research/Technical Scientists
Kazunari YAMADA (concurrent: Senior Technical Scientist,
Beam Dynamics & Diagnostics Team)
Yutaka WATANABE (concurrent: Senior Technical Scientist,
RILAC team)Kazutaka OZEKI (concurrent: Technical Scientist, Cyclotron
Team)
Kenji SUDA (concurrent: Technical Scientist, Cyclotron Team)

Postdoctoral Researcher
Xingguang LIU

List of Publications & Presentations
Publications
Oral Presentations[Domestic Conference]
N. Sakamoto, K. Yamada, K. Suda, K. Ozeki, Y. Watanabe, O. Kamigaito, H. Okuno, “Reduction and resource recycling of highlevel radioactive wastes through nuclear transmutation (6-1) development of prototype superconducting-linac for intense low-beta ion
beams,” Annual Meeting of Atomic Energy Society Japan, Mito, March 20–22, 2019.
N. Sakamoto, K. Yamada, K. Suda, K. Ozeki, Y. Watanabe, O. Kamigaito, H. Okuno, “Advances of accelerator technology development for nuclear transmutation in the ImPACT program-2 prototype of superconducting linear accelerator for intense deuteron beam,”
Meeting of Atomic Energy Society Japan, Okayama, September 5–7, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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. Furthermore
this team works for the demonstration test of the transmutation of 107 Pd.

2. Major Research Subjects(1) Liquid lithium target for production of neutron or muon
(2) Beam window without solid structure(3) Ion implantation and TIMS for the demonstration of the transmutation of 107 Pd

3. Summary of Research Activity(1) Liquid lithium target for production of neutron or muon
(H. Okuno, N. Furutachi)(2) Beam window with solid structure(H. Okuno)(3) Ion plantation and TIMS of 107 Pd(Y. Miyake, Y. Sahoo, M. Takahashi)

Members
Team Leader
Hiroki OKUNO (concurrent: Deputy Group Director, Accelerator Gr.)
Postdoctral Researcher
Yasuto MIYAKE
Contract Researcher
Naoya FURUTACHI
Part-time Workers
Mamoru TAKAHASHI
Akira TAKAGI

YuVin SAHOO- 304 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Research Facility Development Division
Accelerator Group
1. Abstract

The Accelerator Group, consisting of seven teams, pursues various upgrade programs of 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 a variety of 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 shown above govern the development programs
that are not dealt with by a single group, such as intensity upgrade and eﬀective operation. We also discuss the future plans of RIBF
along with other laboratories 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 40% in the last three years,
resulting in the intensity of 72 pnA (5.9 kW) at the exit of the superconducting ring cyclotron. We also started providing intense
vanadium beams for the synthesis of a new element [119] at GARIS II, which was recently moved to the cyclotron facility.
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, and started the test operation in 2018. The beam commissioning
with the upgraded RILAC facility is scheduled in this fiscal year. The accelerating cavities of the ring cyclotron, which has been
suﬀered from the low accelerating voltage, were also modified with this budget. It is expected that the uranium beam intensity will be
increased significantly in near future for the BigRIPS experiments as well as the metallic ion beams for GARIS II experiments for thesynthesis of super heavy elements.
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 At-211 is under development with RI Application ResearchGroup of RNC in the framework of this project. It will be installed and tested in the upgraded RILAC 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,” which is used to improve the overall stripping eﬃciency of theuranium 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. A
preliminary design of the magnets is under progress after intensive optical study of the device. The final goal of this plan is to increase
the uranium beam intensity by 30 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)
Construction of the superconducting linac booster at the RILAC facility
Promotion of the future plan

3. Summary of Research Activity(1) 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.
(2) The maximum intensities of the uranium and xenon beams reached 72 and 102 pnA, respectively, at 345 MeV/nucleon.
(3) The overall beam availability for the RIBF experiments averaged for 5 years from 2013 to 2017 was 92%. It fell down to
79% in 2018 because of several hardware troubles. Eﬀorts to restore the availability to more than 90% are ongoing.
(4) The large infrastructure was properly maintained based on a well-organized cooperation among the related sections.
(5) 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).
(6) An intensity-upgrade plan of the RIBF has been further investigated. Design study of the charge-stripper ring has been started.

Members
Group Director
Osamu KAMIGAITO- 305 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Deputy Group Directors
Hiroki OKUNO (for intensity upgrade)

Nobuhisa FUKUNISHI (for stable and eﬃcient operation)

Junior Research Associate
Takahiro KARINO (Utsunomiya Univ.)
Research Part-time Worker I
Akira GOTO
Research Consultants
Masayuki KASE
Tadashi FUJINAWA

Robert JAMESON
Toshiyuki HATTORI

Visiting Scientists
Eiji KAKO (KEK)
Hirotaka NAKAI (KEK)
Kensei UMEMORI (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- 306 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 (concurrent: Deputy Group Director, Accelerator Group)
Research/Technical Scientists
Hiroshi IMAO (Senior Research Scientist)

Jun-ichi OHNISHI (Senior Technical Scientist)

Technical Scientist
Hiroo HASEBE
Visiting Scientists
Andreas ADELMANN (Paul Scherrer Institute)
Noriyosu HAYASHIZAKI (Tokyo Institue of Technology)

Hironori KUBOKI (KEK)

Junior Research Associate
Naoya IKOMA (Nagaoka Univ. of Technology)
Student Trainees
Taishi SASAKI (Nagaoka Univ. of Technology)

Yoshiki SHIKUMA (Nagaoka Univ. of Technology)

List of Publications & Presentations
Publications[Proceedings]
H. Imao, “Development of Gas stripper at RIBF,” Proceeding of IPAC2018, MOZGBE1, Vancouver, BC, Canada, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Oral Presentations[International Conference etc.]
H. Imao, “Development of Gas stripper at RIBF,” Proceeding of IPAC2018, MOZGBE1, Vancouver, BC, Canada, 2018.
H. Okuno, “Present status of and recent developments at RIKEN RIBF,” 14th International Conference on Heavy Ion Accelerator Technology (HIAT’18), Lanzhou, China, October, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 (Technical Scientist)
Masanori KIDERA (Technical Scientist)

Yoshihide HIGURASHI (Technical Scientist)

Special temporal employee
Yasuyuki KANAI

List of Publications & Presentations
Publications[Proceedings](Original Papers) *Subject to Peer Review
T. Nagatomo et al., “Residual gas eﬀect in LEBT on transverse emittance of multiply charged heavy ion beams extracted from ECR ion
source,” IOP Conf. Proc. 2011, 080004(2018)*
Y. Higurashi et al., “Development of RIKEN 28 GHz SC-ECRIS for production of intense metal ion beam,” Proc. of ECRIS2018,
doi:10.18429/JACoW-ECRIS2018-TUA1
T. Nagatomo et al., “New 28-GHz superconducting electron cyclotron resonance ion source for synthesizing super-heavy elements with
Z > 118,” Proc. of ECRIS2018, doi:10.18429/JACoW-ECRIS2018-TUA3

Oral Presentations[International Conference etc.]
T. Nakagawa, “Developments of RIKEN 28 GHz SC-ECRIS for synthesizing the super-heavy elements,” 14th International Conference
on Heavy Ion Accelerator Technology (HIAT2018), Lanzhou, China, October 22–26, 2018.
T. Nakagawa, “Development of RIKEN 28 GHz SC-ECRIS for production of intense metal ion beam,” International Workshop on ECRIon Sources (ECRIS2018), Catania, Italy, September 10–14, 2018.
T. Nagatomo, “New 28-GHz superconducting electron cyclotron resonance ion source for synthesizing super-heavy elements with Z >118,” Catania, Italy, September 10–14, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 ECR ion source, the frequency-variable RFQ
linac, six frequency-variable main linac cavities, and six energy booster cavities (CSM).

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]
K. Kaneko, E. Ikezawa, T. Ohki, H. Yamauchi, K. Oyamada, M. Tamura, A. Yusa, Y. Watanabe, O. Kamigaito, “Present status of RILAC,”
Proceedings of the 15th Annual Meeting of Particle Accelerator Society of Japan, 1304–1306 (2018).

Posters Presentations[Domestic Conference]
K. Kaneko, E. Ikezawa, T. Ohki, H. Yamauchi, K. Oyamada, M. Tamura, A. Yusa, Y. Watanabe, O. Kamigaito, “Present status of RILAC,”
The 15th Annual Meeting of Particle Accelerator Society of Japan, Nagaoka, Japan, August 7–10, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 (Technical Scientist)

Kenji SUDA (Technical Scientist)

List of Publications & Presentations
Publications[Proceedings]
N. Sakamoto, K. Ozeki, O. Kamigaito, A. Miyamaoto, H. Okuno, K. Suda, Y. Watanabe, K. Yamada, H. Hara, K. Sennyu, T. Yanagisawa,
E. Kako, H. Nakai, K. Umemori, “Construction status of the superconducting Linac at the RIKEN Radioactive Isotope Facility,”
Proceedings of the 29th Linear Accelerator Conference, Beijing, China, September16–21, 2018.
খࢁ྄, ෱ᖒ੟ࣇ, ᖛ஥੣, ੴ઒੝, খྛਗ਼ࢤ, ஥ଜ෢ࢤ, ੢ాູ, ੢ଜ੣, ࣲాॱᠳ, ݄‫ݑډ‬ढ़, ໼෌Ұ৻, 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, ୈ 14 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, p.1395, ๺ւಓେֶ, ࡳຈࢢ, 2018 ೥ 8 ݄ 1–3 ೔.
੢ଜ੣, ෱ᖒ੟ࣇ, ᖛ஥੣, ੴ઒੝, খྛਗ਼ࢤ, খࢁ྄, ஥ଜ෢ࢤ, ੢ాູ, ࣲాॱᠳ, ݄‫ݑډ‬ढ़, ໼෌Ұ৻, 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੒, ࢁᖒलߦ, ʮཧ‫ ݚ‬RIBF ʹ͓͚Δ
ϦϯάαΠΫϩτϩϯӡసͷ‫ݱ‬ঢ়ใࠂʯ, ୈ 14 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ๺ւಓେֶ, ࡳຈࢢ, 2018 ೥ 8 ݄ 1–3 ೔.

Oral Presentations[International Conference etc.]
N. Sakamoto, K. Ozeki, O. Kamigaito, A. Miyamaoto, H. Okuno, K. Suda, Y. Watanabe, K. Yamada, H. Hara, K. Sennyu, T. Yanagisawa,
E. Kako, H. Nakai, K. Umemori, “Construction Status of the Superconducting Linac at the RIKEN Radioactive Isotope Facility,” 29th
Linear Accelerator Conference, Beijing, China, September 16–21, 2018.

Posters Presentations[Domestic Conference]খࢁ྄, ෱ᖒ੟ࣇ, ᖛ஥੣, ੴ઒੝, খྛਗ਼ࢤ, ஥ଜ෢ࢤ, ੢ాູ, ੢ଜ੣, ࣲాॱᠳ, ݄‫ݑډ‬ढ़, ໼෌Ұ৻, 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, ୈ 14 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, p.1395, ๺ւಓେֶ, ࡳຈࢢ, 2018 ೥ 8 ݄ 1–3 ೔.
੢ଜ੣, ෱ᖒ੟ࣇ, ᖛ஥੣, ੴ઒੝, খྛਗ਼ࢤ, খࢁ྄, ஥ଜ෢ࢤ, ੢ాູ, ࣲాॱᠳ, ݄‫ݑډ‬ढ़, ໼෌Ұ৻, ਢా݈࢚, ౻‫ר‬ਖ਼थ, ෱੢ெ- 311 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)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੒, ࢁᖒलߦ, ʮཧ‫ ݚ‬RIBF ʹ͓͚Δ
ϦϯάαΠΫϩτϩϯӡసͷ‫ݱ‬ঢ়ใࠂʯ, ୈ 14 ճ೔ຊՃ଎‫ֶث‬ձ೥ձ, ๺ւಓେֶ, ࡳຈࢢ, 2018 ೥ 8 ݄ 1–3 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 72-pnA uranium, 102-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 (concurrent; Deputy Group Director,
Accelerator Gr.)
Research/Technical Scientists
Masaki FUJIMAKI (Senior Technical Scientist)
Kazunari YAMADA (Senior Technical Scientist)
Keiko KUMAGAI (Senior Technical Scientist)

Akito Uchiyama
UCHIYAMA(Technical
Scientist)(Technical
Scientist)
Tamaki WATANABE (Senior Technical Scientist)

Expert Technician
Misaki KOMIYAMA
Part-time Worker
Makoto NAGASE
Visiting Scientists
Kenichi ISHIKAWA (Univ. of Tokyo)
Takuya MAEYAMA (Kitasato Univ.)

Shin-ichiro HAYASHI (Hiroshima Int’l Univ.)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
T. Maeyama, Y. Ishida, Y. Kudo, K. Fukasaku, K. L. Ishikawa, N. Fukunishi, “Polymer gel dosimeter with AQUAJOINT as hydrogel
matrix,” Radiat. Phys. Chem. 146, 121–125, doi:0.10216/j.radphyschem.2018.01.014 (2018).
T. Nishi, K. Itahashi, G. P. A. Berg, H. Fujioka, N. Fukuda, N. Fukunishi, H. Geissel, R. S. Hayano, S. Hirenzaki, K. Ichikawa, N. Ikeno,
N. Inabe, S. Itoh, M. Iwasaki, D. Kameda, S. Kawase, T. Kubo, K. Kusaka, H. Matsubara, S. Michimasa, K. Miki, G. Mishima,
H. Miya, H. Nagahiro, M. Nakamura, S. Noji, K. Okochi, S. Ota, N. Sakamoto, S. Suzuki, H. Takeda, Y. K. Tanaka, K. Todoroki,
K. Tsukada, T. Uesaka, Y. N. Watanabe, H. Weick, H. Yamakami, K. Yoshida, “Spectroscopy of pionic atoms in 122 Sn(d, 3 He) reaction
and angular dependence of the formation cross section,” Phys. Rev. Lett. 120, 152502 (2018).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Oral Presentations[International Conference etc.]
T. Nagatomo, Y. Higurashi, J. Ohnishi, A. Uchiyama, K. Kumagai, M. Fujimaki, N. Fukunishi, N. Sakamoto, T. Nakagawa, O. Kamigaito,“New 28-GHz superconducting electron cyclotron resonance ion source for synthesizing super-heavy elements with Z > 118,” 23th.
Int. Workshop on ECR Ion Sources (ECRIS2018), TUA3 (pp. 53–57), Catania, Italy, September 2018.

[Domestic Conference]
T. Watanabe, H. Imao, O. Kamigaito, N. Sakamoto, N. Fukunishi, M. Fujimaki, K. Yamada, Y. Watanabe, R. Koyama, T. Toyama,
T. Miyao, A. Miura, “Development of beam energy position monitor system for RIKEN superconducting acceleration cavity,” 15th
Annual Meeting of Particle Accelerator Society of Japan, pp. 49–54, Nagaoka, Japan, August 2018.

Posters Presentations[International Conference etc.]
A. Uchiyama, T. Nagatomo, Y. Higurashi, J. Ohnishi, T. Nakagawa, M. Komiyama, N. Fukunishi, H. Yamauchi, M. Tamura, “Design ofreliable control with star-topology fieldbus communication for an electron cyclotron resonance ion source at RIBF,” 12th International
Workshop on Personal Computers and Particle Accelerator Controls (PCaPAC2018), WEP30, Hsinchu, Taiwan, October 2018.
M. Komiyama, M. Fujimaki, N. Fukunishi, K. Kumagai, A. Uchiyama, “Recent development of the RIKEN RI Beam Factory control
system,” 12th International Workshop on Personal Computers and Particle Accelerator Controls (PCaPAC2018), WEP15, Hsinchu,
Taiwan, October 2018.

[Domestic Conference]
T. Watanabe, H. Imao, O. Kamigaito, N. Sakamoto, N. Fukunishi, M. Fujimaki, K. Yamada, Y. Watanabe, R. Koyama, T. Toyama,
T. Miyao, A. Miura, “Development of beam energy position monitor system for RIKEN superconducting acceleration cavity,” 15th
Annual Meeting of Particle Accelerator Society of Japan, pp. 49–54, Nagaoka, Japan, August 2018.
A. Uchiyama, M. Komiyama, “Current status of server and syste, infrastructure for RIBF control system,” 15th Annual Meeting of Particle
Accelerator Society of Japan, pp. 597–600, Nagaoka, Japan, August 2018.
K. Kobayashi, K. Ozeki, A. Goto, J. Ohnishi, Y. Oshiro, S. Fukuzawa, M. Hamanaka, S. Ishikawa, R. Koyama, T. Nakamura, M. Nishida,
M. Nishimura, J. Shibata, N. Tsukiori, K. Yadomi, K. Kaneko, K. Oyamada, M. Tamura, A. 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, N. Sakamoto, K. Suda, A. Uchiyama, S. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, Y. Kotaka, “Status
report on operation of RIKEN AVF cyclotron,” 15th Annual Meeting of Particle Accelerator Society of Japan, pp. 1293–1297, Nagaoka,
Japan, August 2018.
J. Shibata, K. Suda, S. Fukuzaw, M. Hamanaka, S. Ishikawa, K. Kobayashi, R. Koyama, T. Nakamura, M. Nishida, M. Nishimura,
N. Tsukiori, K. Yadomi, T. Dantsuka, M. Fujimak, 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. Ozeki, A. Uchiyama, S. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa, “Status report of the operation of RIBF Ring cyclotrons,” 15th Annual Meeting of Particle Accelerator Society of Japan, pp. 1298–1303,
Nagaoka, Japan, August 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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, H. Okuno).

Members
Team Leader
Hiroki OKUNO (concurrent: Deputy Group Director, Accelerator Group)
Research/Technical Scientist
Masato NAKAMURA (Senior Technical Scientist)
Expert Technicians
Takeshi MAIE

Tomoyuki DANTSUKA

Part-time Workers
Shizuho TSURUMA

Mayumi KUROIWA- 315 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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.)Research/Technical Scientist
Shu WATANABE (Senior Technical Scientist)
Special Temporary Employee
Hideyuki YAMASAWA- 316 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 an experimental installations under testing and a common element enabling multiple-use. This will stop high-energy RI beams
in a gas-catcher 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 massmeasurement for extremely rare exotic nuclei. This is now open for an experimental proposal application, and has already performed
PAC-approved experiments. All instrumentations were designed to maximize the research potential of the world’s most intense RI
beams, and the exclusive equipment available at the RI Beam Factory makes experimental challenges possible. Technologies andexperiences accumulated in this group will be able to provide opportunities of 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 ProjectBeam recycling development (in future plan)

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 almost ready for theelectrons 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. SLOWRI is now under test experiments to establish a slow RI beam production using two types ofgas cells. PALIS has been commissioned from 2015, and basic functions such as, for instance, the RI-beam stopping in Ar gas cell andthe extraction from the gas cell have beam evaluated. RF ion-guide gas cell is now under testing and it is planned to be commissioned
in next year. Future plans for these projects are described in subsections.
We are going to start a new project from next year. According to the future plan of Nishina center, we are going to start to develop abeam re-cycling technique. A crculation 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 loses a energy and the emittance grows up turn by turn because of existing
internal target. In order to establish a beam re-cycling technique, the energy loss and the emittance growth have to be compensatedby 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 these novel technique, we are going toinstall 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 sLSR is equipped by acceleration devices and beam-cooling devices necessary in our R&D study, and was
originally constructed at the Institute for Chemical Research, Kyoto University more than ten years ago. This will be moved to RIBF
in this year, and re-constructed by the SCRIT facility in following year.

Members
Group Director
Masanori WAKASUGIVisiting Scientist
Akira OZAWA (Univ. of Tsukuba)
Research Fellow
Mamoru TOGASHI (Rikkyo Univ.)
Student Trainees
Mitsuki HORI (Rikkyo Univ.)
So SATO (Rikkyo Univ.)
Nobuaki UCHIDA (Rikkyo Univ.)

Moe NAKANO (Rikkyo Univ.)
Shinnosuke SASAMURA (Rikkyo Univ.)- 317 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Part-time Woker
Mitsuki HORI

List of Publications & Presentations
Publications and presentations for each project team are listed in subsections.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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. 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 flight mass 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. At SLOWRI facility, third prototype
SLOWRI is under construction, which is 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 measurements with other
BigRIPS experiments.
An online commissioning experiment of parasitic low-energy production facility (PALIS) was performed and confirmed that the
PALIS setup can coexist with other BigRIPS experiments. Currently, PARIS gas cell is under on- and oﬀ-line commissioning.

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.
Development of highly charged ion trap for fundamental physics

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. The beam transport line consists of four dipole magnets, two focal plane chambers, 62 electrostatic quadrupole singlets,
11 electrostatic quadrupole quartets and 7 beam profile monitors. 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 forcollection of ions from the gutter carpet and for transporting the ions towards the exit, and a small rf carpet for extraction from the gascell. In FY2018, ion extraction test at oﬀ-line using this carpet has been successfully performed with about 60% extraction eﬃciency
to ions gathered on 1st carpet. We will install the RF-carpet gas cell combined with MRTOF at F11 of BigRIPS at first, where theon-line commissioning and systematic mass measurements will be started from FY2019. At F11, symbiotic measurements with other
BigRIPS experiments 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 (MR-TOF) 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 transuranium 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 MR-TOF. 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. The highest precisions, achievedfor Ga isotopes, reached a level of 0.03 ppm. The masses of four isotopes of Es and Md were measured for the first time, allowing
for confirmation of the N = 152 shell closure in Md. Using these new mass data as anchor-points, the masses of seven isotopes ofsuper-heavy elements up to Mt were indirectly determined. For comprehensive mass measurements of all available nuclides, multiple- 319 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

units of gas catchers and MR-TOF devices will be placed at GARIS-III, KISS as well as the BigRIPS + SLOWRI facilities of RIBF.
(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.
An online setup has been fabricated in FY2013 and the first online commissioning took place in FY2015. It was confirmed that
the PALIS gas cell is not deleterious for BigRIPS experiments, and a reasonable amount of radioactive Cu isotopes was extracted
from the cell by gas flow. At oﬀ-line, using α rays from Am source, impurities inside the gas cell have been investigated. Thanks tobaking the gas cell with gas flow, almost impurities have been successfully suppressed at oﬀ-line condition. Technical developments
are under progress in on- and oﬀ-line commissioning.
(5) Development of highly charged ion trap for fundamental physics
Some particular transitions in highly charged ions (HCI) are sensitive to the temporal variation of the fine structure constant.
High precision spectroscopy of such transitions can be a probe for the verification of fundamental physics. A cryogenic ion trap setup
consisting of a micro electron beam ion trap (µEBIT) and a linear RFQ ion trap in a compact cryogenic enclosure is under development
in collaboration with Quantum Metrology Laboratory. First candidate HCIs, such as Ba7+ or Ho14+ can be produced in the µEBIT
and sympathetically cooled by laser cooled Be+ ions in the linear RFQ trap, following which the “clock” transition can be measured
by electron-shelving spectroscopy. The final target is 249 Cf15+ , which is known to have the most sensitive transition to the temporalvariation of the fine structure constant.

Members
Team Leader
Hironobu ISHIYAMA
Research/Technical Scientists
Takao KOJIMA (Senior Research Scientist)
Aiko TAKAMINE (concurrent; Nuclear Spectroscopy Laboratory)

Tetsu SONODA (Technical Scientist)
Takeshi MAIE (concurrent; Cryogenic Technology Team)Special Postdoctoral Researcher
Marco ROSENBUSCH
Part-time Worker
Ichiro KATAYAMA
Visiting Scientists
Hans A SCHUESSLER (Texas A&M Univ.)
Kunihiro OKADA (Sophia Univ.)
Hermann WOLLNIK (Univ. of Giessen)
Volker SONNENSCHEIN (Nagoya Univ.)

Hideki IIMURA (JAEA)
Mikael REPONEN (JYFL)
Hideki TOMITA (Nagoya Univ.)- 320 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)Student Trainees
Naoki KIMURA (Sophia Univ.)
Oohashi (Nagoya
Univ.)
Masaya OOHASHI(NagoyaUniv.)

Kento Suzuki(Univ.
of ofElectro-Communications)SUZUKI(Univ.
Electro-Communications)Ryunosuke Kodama(Univ.
of Electro-Communications)
KODAMA(Univ.
of Electro-Communications)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
M. Rosenbusch, Y. Ito, P. Schiry, M. Wada, D. Kaji, K. Morimoto, H. Haba, S. Kimura, H. Koura, M. MacCorimik, H. Miyatake,J. Y. Moon, K. Morita, I. Murray, T. Niwase, A. Ozawa, M. Reponen, A. Takamine, T. Tanaka, H. Wollnik, “New mass anchor points
for neutron-deficient heavy nuclei from direct mass measurements of radium and actinium isotopes,” Phys. Rev. C 97, 064306 (2018). *N. Kimura, R. Kodama, K. Suzuki, S. Ohishi, M. Wada, K. Okada, N. Ohmae, H. Katori, N. Nakamura, “Direct wavelength measurementof the visible M1 transition in Ba7+ with a novel calibration method,” Plasma and Fusion Research 14, 1201021 (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. X. Watanabe, H. Wollnik, S. Yamaki, “First direct mass measurements of nuclides around Z = 100 with a multireflection time-offlight mass spectrograph,” Phys. Rev. Lett. 120, 152501 (2018) .*T. Sonoda, H. Iimura, M. Reponen, M. Wada, I. Katayama, V. Sonnenscheine, T. Takamatsu, H. Tomita, T. M. Kojima, “The laser andoptical system for the RIBF-PALIS experiment,” Nucl. Instrum. Methods Phys. Res. A 877, 118–123 (2018). *S. Kimura, Y. Ito, D. Kaji, P. Schury, M. Wada, H. Haba, T. Hashimoto, Y. Hirayama, M. MacCormick, H. Miyatake, J. Y. Moon,
K. Morimoto, M. Mukai, I. Murrya, A. Ozawa, M. Rosenbusch, H. Schatz, A. Takamine, T. Tanaka, Y. X. Watanabe, H. Wollnik,“Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down tto 35-ppb via multireflection time-offlight mass spectrograph,” Int. J. Mass Spectrom. 430, 134–142 (2018).
T. M. Kojima, “Ion guiding in macro-size insulating capillaries: straight, tapered, and curved shapes,” J. Phys. B: At. Mol. Opt. Phys. 51,
042001 (2018). *K. Imamura, Y. Matsuo, W. Kobayashi, T. Egami, M. Sanjo, A. Takamine, T. Fujita, D. Tominaga, Y. Nakamura, T. Furukawa, T. Wakui,
Y. Ichikawa, H. Nishibata, T. Sato, A. Gladkov, L. C. Tao, T. Kawaguchi, Y. Baba, M. Iijima, H. Gonda, Y. Takeuchi, R. Nakazato,
H. Odashima, H. Ueno, “Absolute optical absorption cross-section measurement of Rb atoms injected into superfluid helium using
energetic ion beams,” App. Phys. Exp. 12, 016502 (2019). *M. Reponen, V. Sonnenschein, T. Sonoda, H. Tomita, M. Oohashi, D. Matsui, M. Wada, “Towards in-jet resonance ionization spectroscopy: An injection-locked Titanium:Sapphire laser system for the PALIS-facility,” Nucl. Instrum. Methods Phys. Res. A 908,
236–243 (2018). *Oral Presentations[International Conference etc.]
A. Takamine, “Laser spectroscopy project at the SLOWRI facility in RIKEN,” 20th Northeastern Asian Symposium-2018 on Nuclear
Physics in the 21st Century, Nagoya, Japan, September 18–19, 2018.
A. Takamine, “Prospects for laser spectroscopy project at the SLOWRI facility in RIKEN RIBF,” 2018 Korea Physics Society Fall
Meeting, Changwon, Korea, October 24–26, 2018.
N. Kimura, R. Kodama, K. Suzuki, S. Ohishi, M. Wada, K. Okada, N. Ohmae, H. Katori, N. Nakamura, “Visible spectroscopy of highly
charged barium ions in a compact electron beam ion trap with a buﬀer gas calibration method,” 19th International Conference on the
Physics of Highly Charged Ions (HCI2018), Lisboa, Portugal, September, 2018.
N. Kimura, R. Kodama, K. Suzuki, S. Ohishi, M. Wada, K. Okada, N. Ohmae, H. Katori, N. Nakamura, “Applications of buﬀer gas in
a compact EBIT for reliable spectroscopic calibration,” The 13th International Symposium on Electron Beam Ion Sources and Traps(EBIST2018), Shanhai, China, October, 2018.
M. Rosenbusch, “Status and future plans for MRTOF mass measurements at RIKEN-RIBF,” International Conference on Electromagnetic
Isotope separator and related topics (EMIS XVIII), CERN (Geneva), Swiss, September 16–21, 2018.
M. Rosenbusch, “MRTOF mass measurements at RIBF: Recent measurements of heavy isotopes and future plans for the super-heavy
region,” TASCA workshop, GSI (Darmstadt), Germany, September 25, 2018.
M. Rosenbusch, “Recent successes of multi-reflection devices at RIKEN’s RIBF facility and some thoughts about highly accurate mass
calibration using ion traps,” 10th International Conference on Charged Particle Optics (CPO-10), Key West (Florida), USA, October
17–21, 2018.
M. Rosenbusch, “Follow-ups on great achievements: New MRTOF-MS projects at RIKEN-RIBF,” Fifth joint meeting of the Division of
Nuclear Physics of the American Physical Society (APS) with the nuclear physicists of the Physical Society of Japan (JPS),” Hawaii,
USA, October 23–27, 2018.
H. Ishiyama, “SLOWRI and related topics,” RIBF Seminar, Wako, Japan, July 3, 2018.
H. Ishiyama, “Present status of SLOWRI,” RIBF Users Meeting 2018, Wako, Japan, September 5, 2018.
H. Ishiyama, “Present status of SLOWRI,” SSRI-PNS collaboration meeting 2018, Wako, Japan, September 4, 2018.

[Domestic Conference]- 321 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)ߴๆѪࢠ, ʮߴภ‫ ۃ‬RI ϏʔϜͷੜ੒ͱ֩ɾ෺࣭Պֶ‫΁ڀݚ‬ͷԠ༻ʯ, ৽ֶज़ྖҬ‫ڀݚ‬ʮӉ஦‫؍‬ଌ‫ݕ‬ग़‫ࢠྔͱث‬ϏʔϜͷग़ձ͍. ৽ͨͳԠ༻΁ͷՍ͚‫ڮ‬.ʯ, ΩοΫΦϑγϯϙδ΢Ϝ, ઋ୆, 2018 ೥ 12 ݄ 17–18 ೔.

- 322 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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.

2. Major Research Subjects(1) Developments of heavy-ion storage ring(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 the 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 ∼10 ppm. In addition, we have improved
the extraction eﬃciency to 2% by considering the matching condition between the emittance of injection events and the acceptanceof R3. This extraction eﬃciency was suﬃcient to conduct the accepted two proposals: mass measurements of Ni isotopes and massmeasurements 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 2019.

Members
Team Leader
Masanori WAKASUGI (concurrent: Group Director, Instrumentations Development Gr.)
Research/Technical Scientist
Yoshitaka YAMAGUCHI (Technical Scientist)- 323 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Expert Technician
Takeshi MAIE (concurrent: Cryogenic Technology Team)
Postdoctoral Researcher
Yasushi ABE
Special Postdoctoral Researcher
Fumi SUZAKI

List of Publications & Presentations
Publications
Oral Presentations[International Conference etc.]
S. Naimi, “The Rare-RI Ring ready to conguer Terra Incognita—Mass measurement of r-process nuclei at RIKEN—,” FRIB and theGW170817 kilonova Workshop, East Lansing, USA, July, 2018.
T. Yamaguchi, “Rare-RI Ring project in RIKEN and a proposal at CSRe,” Symposium on Precision Physics Experiments with Stored
Highly Charged Ions at Low Energies, Lanzhou, China, August, 2018.
D. Nagae, S. Omika, Y. Abe, Y. Yamaguchi, F. Suzaki, K. Wakayama, N. Tadano, R. Igosawa, K. Inomata, H. Arakawa, K. Nishimuro,
T. Fujii, T. Mitsui, T. Yamaguchi, T. Suzuki, S. Suzuki, T. Moriguchi, M. Amano, D. Kamioka, A. Ozawa, S. Naimi, Z. Ge, Y. Yanagisawa, H. Baba, S. Michimasa, S. Ota, G. Lorusso, Y. A. Litvinov, M. Wakasugi, T. Uesaka, Y. Yano, “Demonstration of mass measurement using Rare-RI Ring,” The IX International Symposium on EXOtic Nuclei (EXON-2018), Petrozavodsk, Russia, September,
2018.
Y. Yamaguchi, “Rare-RI Ring in cyclotron facility RIBF,” The International Conference on Electromagnetic Isotope Separators andRelated Topics (EMIS2018), Geneva, Switzerland, September, 2018.
A. Ozawa, “Mass measurements in Rare-RI Ring in RIBF,” Workshop on Physics at HIAF High-Energy Beam Lines, Beijing, China,
December, 2018.

[Domestic Conference]ࢁ‫وޱ‬೭, ʮPrecision mass spectrometry of stored exotic nucleiʯ, ॏྗ೾‫؍‬ଌ࣌୅ͷ r ϓϩηεͱෆ҆ఆ֩, ࿨ޫ, 2018 ೥ 6 ݄.
޲Ҫ΋΋, ʮ‫ك‬গ RI Ϧϯάʹ͓͚Δதੑࢠա৒ Ni ྖҬͷ࣭ྔଌఆʯ, ֩σʔλͱॏ‫ݩ‬ૉ߹੒Λத৺ͱ͢ΔӉ஦֩෺ཧ‫ڀݚ‬ձ, ࡳຈ,2019 ೥ 3 ݄.
ࢁ‫ޱ‬༝ߴ, Ѩ෦߁ࢤ, ऱቌ;Έ, एਿণಙ, ௕ߐେี, େᙈॢҰ࿕, খ୔‫ݦ‬, S. Naimi, H. Li, Z. Ge, ্ࡔ༑༸, ࢁ‫وޱ‬೭, ߥ઒༟थ, Ҵా߁ਓ, ழ‫ۢވ‬ඒ, খྛ޹জ, ࡔ্‫ޢ‬, ੢ࣨࠃޫ, ࡉҪॣ, ԣా݈࣍࿠, ‫ܠ‬ᖒྯԝ, ্Ԭେ‫ى‬, ޲Ҫ΋΋, ৿‫ޱ‬఩࿕, ླ໦৳࢘, Q. Wang,େా৾ี, ๺ଜಙོ, ૿ԬᠳҰ࿕, ಓਖ਼৽Ұ࿠, Y. A. Litvinov, ʮ‫ك‬গ RI Ϧϯάͷ࣭ྔଌఆʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱
Ԭ, 2019 ೥ 3 ݄.
Ѩ෦߁ࢤ, ௕ߐେี, ࢁ‫ޱ‬༝ߴ, ্ࡔ༑༸, S. Naimi, ऱቌ;Έ, एਿণಙ, ߥ઒༟थ, Ҵా߁ਓ, ழ‫ۢވ‬ඒ, େᙈॢҰ࿕, খྛ޹জ, ࡔ্‫ޢ‬, ੢ࣨࠃޫ, ࡉҪॣ, ԣా݈࣍࿠, ࢁ‫وޱ‬೭, ‫ܠ‬ᖒྯԝ, ্Ԭେ‫ى‬, ޲Ҫ΋΋, ৿‫ޱ‬఩࿕, খ୔‫ݦ‬, ླ໦৳࢘, Z. Ge, H. Li, Q. Wang,େా৾ี, ๺ଜಙོ, ૿ԬᠳҰ࿕, ಓਖ਼৽Ұ࿠, Y. A. Litvinov, K. Wang, ʮ‫ك‬গ RI Ϧϯά࣮‫͚͓ʹݧ‬Δ୯Ұ֩छબ୒๏ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄.
ऱቌ;Έ, Ѩ෦߁ࢤ, एਿণಙ, ࢁ‫ޱ‬༝ߴ, ఱ໺কಓ, ߥ઒༟थ, അ৔ल஧, Z. Ge, ࡉҪॣ, Ҵా߁ਓ, ழ‫ۢވ‬ඒ, ্Ԭେ‫ى‬, ๺ଜಙོ, খྛ޹জ, H. Li, Y. A. Litvinov, ૿ԬᠳҰ࿕, ಓਖ਼৽Ұ࿠, ৿‫ޱ‬఩࿕, ௕ߐେี, S. Naimi, ੢ࣨࠃޫ, େᙈॢҰ࿕, େా৾ี, খ୔‫ݦ‬, ླ໦৳࢘, ্ࡔ༑༸, एࢁਗ਼ࢤ, ࢁ‫وޱ‬೭, ʮ‫ڞ‬໐γϣοτΩʔϐοΫΞοϓΛ༻͍ͨ‫ك‬গ RI Ϧϯάͷ౳࣌ੑ৔ௐ੔ʯ, ೔ຊ෺ཧֶ
ձୈ 74 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄.

Posters Presentations[International Conference etc.]
S. Omika, 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, Y. Yamaguchi, “Development of a new in-ring beam monitor in the RareRI Ring,” The International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS2018), Geneva, Switzerland,
September 2018.
Z. Ge, T. Uesaka, S. Naimi, D. Nagae, Y. Abe, S. Omika, F. Suzaki, H. Li, Y. Yamaguchi, M. Wakasugi, K. Wakayama, T. Yamaguchi,
H. Arakawa, K. Inomata, K. Nishimuro, T. Kobayashi, A. Ozawa, S. Suzuki, T. Moriguchi, A. Kitagawa, S. Sato, G. Lorusso, Y. Yano,“High-resolution selection and identification of secondary beams for mass measurements,” The 7th International Conference on Trapped
Charged Partices and Fundamental Physics (TCP2018), Michigan, USA, September–October 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 have been developing several instruments. One is the introduction of the surface-ionization type ion source at ERISin 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.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Members
Team Leader
Masanori WAKASUGI (concurrent: Group Director, Instrumentations Development Gr.)
Research/Technical Scientists
Masamitsu WATANABE (Senior Research Scientist)

Tetsuya OHNISHI (Senior Technical Scientist)

Contract Researcher
Akitomo ENOKIZONO
Expert Technician
Taleshi MAIE (concurrent: Cryogenic Technology Team)
Research Consultants
Tadaaki TAMAE
Masahiro HARA

Shin-ichi ICHIKAWA
Takashi EMOTO

Senior Visiting Scientist
Toshitada HORI (Hiroshima University)
Visiting Scientists
Shuo WANG (Shandong University)
Ryo OGAWARA (National Institute of Radiological Sciences)
Yuki HONDA (Tohoku University)

Toshimi SUDA (Tohoku University)
Kyo TSUKADA (Tohoku University)

Student Trainees
Keita KASAMA (Tohoku University)
Syota TAKAYAMA (Tohoku University)
Kazuki NAMBA (Tohoku University)

Hikari WAUKE (Tohoku University)
Taihei AOYAGI (Tohoku University)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
M. Wakasugi, M. Togasaki, T. Ohnishi, K. Kurita, R. Toba, M. Watanabe, K. Yamada, “FRAC: Fringing-RF-field-activated dc-to-pulse
converter for low-energy ion beams,” Rev. Sci. Instrum. 89, 095107 (2018).
A. Enokizono, T. Ohnishi, K. Tsukada, “The SCRIT electron scattering facility at RIKEN: The world’s first electron femtoscope forshort-lived unstable nuclei,” Nucl. Phys. News 28, 18–22 (2018).

[Proceedings]
T. Ohnishi, A. Enokizono, M. Hara, M. Hori, S. Ichikawa, M. Wakasugi, M. Watanabe, K. Adachi, T. Fujita, T. Hori, K. Kurita, M. Togasaki, N. Uchida, K. Yamada, T. Suda, T. Tamae, K. Tsukada, “The SCRIT electron scattering facility project at the RIKEN RI Beam
Factory,” Acta Phy. Pol. B 49, 483–493 (2018).

Oral Presentations[International Conference etc.]
K. Tsukada, “Present status of the SCRIT electron scattering facility,” 5th Joint Meeting of the APS Division of Nuclear Physics and the
Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
K. Tsukada (invited), “Electron scattering from 208 Pb and 132 Xe ions at the SCRIT facility,” The 7th international conference on Trapped
Charged Particles and Fundamental Physics (TCP2018), Traverse, Michigan, USA, September 30–October 5, 2018.
K. Tsukada (invited), “Present status of the electron scattering experiments at the SCRIT facility,” ECT* conference, “Probing exotic
structure of short-lived nuclei by electron scattering,” Trento, Italy, July 16–20, 2018.

[Domestic Conference]௩ా‫ڿ‬, ʮPresent status of the SCRIT electron scattering facilityʯ, ELPH ‫ڀݚ‬ձ, ౦๺େֶ, ઋ୆, 2019 ೥ 3 ݄.
∁ࢁ঵ଡ, ੨༄ହฏ, ࢢ઒ਐҰ, େ੢఩࠸, ӿԂতஐ, ּؒ‫ܡ‬ଠ, ‫ా܀‬࿨޷, ࠤ౻૵, ਢాརඒ, ‫ߐۄ‬஧໌, ௩ా‫ڿ‬, த໺๖ֆ, ೆ೾࿨‫ر‬,‫ݪ‬խ߂, ງར‫ڡ‬, ຊଟ༎‫ه‬, ࿨Ӊ‫͔ͻܚ‬Γ, एਿণಙ, ౉ᬑਖ਼ຬ, ʮిࢠɾෆ҆ఆ֩ࢄཚ࣮‫༻ݧ‬υϦϑτνΣϯόʔͷ։ൃͱੑೳධ
Ձʯ, ೔ຊ෺ཧֶձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
࿨Ӊ‫͔ͻܚ‬Γ, ੨༄ହฏ, ࢢ઒ਐҰ, େ੢఩࠸, ӿԂতஐ, ּؒ‫ܡ‬ଠ, ‫ా܀‬࿨޷, ࠤ౻૵, ਢాརඒ, ∁ࢁ঵ଡ, ‫ߐۄ‬஧໌, ௩ా‫ڿ‬, த໺๖ֆ, ೆ೾࿨‫ر‬, ‫ݪ‬խ߂, ງར‫ڡ‬, ຊଟ༎‫ه‬, एਿণಙ, ౉ᬑਖ਼ຬ, ʮSCRIT ࣮‫͍༻ʹݧ‬ΔిࢠεϖΫτϩϝʔλʔͷਫ਼ີ࣓৔ଌఆʯ
,೔ຊ෺ཧֶձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)௩ా‫( ڿ‬invited),ʮThe SCRIT electron scattering facility: Toward the world’s first study of unstable nuclei by electron scatteringʯ, PRL60
प೥γϯϙδ΢Ϝ, ೔ຊ෺ཧֶձ, ৴भେֶ, দຊ, 2018 ೥ 9 ݄.
಺ా৴ত, ଍ཱߐհ, ࢢ઒ਐҰ, ӿԂতஐ, େ੢఩࠸, ּؒ‫ܡ‬ଠ, ‫ా܀‬࿨޷, ਢాརඒ, ‫ߐۄ‬஧໌, ௩ా‫ڿ‬, ‫ށ‬έ࡚Ӵ, ‫ݪ‬խ߂, ౻ాफ़޿,ງॆ‫ر‬, ງར‫ڡ‬, ࢁాߞฏ, एਿণಙ, ౉ᬑਖ਼ຬ, ʮSCRIT ࣮‫͚͓ʹݧ‬Δั֫͞ΕͨΠΦϯͷϞδϡϨʔγϣϯґଘੑʯ, ೔ຊ෺ཧֶձ, ౦‫ژ‬ཧՊେֶ, ઍ༿, 2018 ೥ 3 ݄.
ງॆ‫ر‬, ӿԂতஐ, େ੢఩࠸, ‫ݪ‬խ߂, ‫ా܀‬࿨޷, एਿণಙ, ౉ᬑਖ਼ຬ, ʮిࢠ஝ੵϦϯάʹ͓͚Δೋޫࢠ૬ؔΛ༻͍ͨόϯν௕Ϟχλʔ։ൃʯ, ೔ຊ෺ཧֶձ, ౦‫ژ‬ཧՊେֶ, ઍ༿, 2018 ೥ 3 ݄.
ߴࢁ঵ଡ, ਢాརඒ, ௩ా‫ڿ‬, ຊଟ༎‫ه‬, ‫ߐۄ‬஧໌, ּؒ‫ܡ‬ଠ, ੨༄ହฏ, for the SCRIT collaboration, ʮSCRIT ిࢠε΃Ϋτϩϝʔλʔੑೳ޲্ʹ޲͚ͨඈ੻‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ೔ຊ෺ཧֶձ, ౦‫ژ‬ཧՊେֶ, ઍ༿, 2018 ೥ 3 ݄.

Posters Presentations[International Conference etc.]
T. Ohnishi, S. Ichikawa, M. Nakano, K. Kurita, M. Wakasugi, “Present status of electron-beam-driven RI separator for SCRIT at RIKEN
RI Beam Factory,” 18th International Conference on Electromagnetic Isotope separators and Related Topics (EMIS2018), Geneva,
Switzerland, September 16–21, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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
Group Director
Hideki UENO (∼ 2018.03)

Tomohiro UESAKA (2018.04 ∼)Senior Visiting Scientists
Toshio KOBAYASHI (Tohoku University)

Jerry NOLEN (Argonne National Laboratory)

Visiting Scientist
Toshiyuki KUBO (Michigan State University)
Student Trainee
Fumitaka ENDO (Tohoku University)- 328 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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)
Masao OHTAKE (Senior Technical Scientist)

Kensuke KUSAKA(Senior Technical Scientist)
Hiroyuki TAKEDA (Technical Scientist)
Naoki FUKUDA (Technical Scientist)

Contract Researchers
Yohei SHIMIZU
Deuk Soon AHN

Hiroshi SUZUKI

Postdoctoral Researcher
Zeren KORKULU
Research Consultant
Hidekazu KUMAGAI
Part-time Worker
Tetsuro KOMATSUBARA
Visiting Scientists
Daisuke KAMEDA (TOSHIBA Corp.)
Michael Andrew FAMIANO (Western Michigan University)
Daniel Pierre BAZIN (NSCL, MSU)
Bradley Marc SHERRILL (NSCL, MSU)
Yutaka MIZOI (Osaka Elec.-Com. University)- 329 -

Naohito IWASA (Tohoku University)
Tuomas Arne Santeri GRAHN (University of Jyvaskyla)
Oleg Borisovich TARASOV (NSCL, MSU)
Hans GEISSEL (GSI)David Joseph MORRISSEY (NSCL, MSU)

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Alfredo ESTRADE VAZ (Central Michigan University)
Mauricio PORTILLO (NSCL, MSU)

Alan Matthew AMTHOR (Bucknell University)
Kazuo IEKI (Rikkyo University)

Student Trainees
Junki AMANO (Rikkyo University)
Ha JEONGSU (Seoul National University)

Takahiro SAKAKIBARA (Tohoku University)
Shunki ISHIKAWA (Tohoku University)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
N. Fukuda, T. Kubo, D. Kameda, N. Inabe, H. Suzuki, Y. Shimizu, H. Takeda, K. Kusaka, Y. Yanagisawa, M. Ohtake, K. Tanaka,
K. Yoshida, H. Sato, H. Baba, M. Kurokawa, T. Ohnishi, N. Iwasa, A. Chiba, T. Yamada, E. Ideguchi, S. Go, R. Yokoyama, T. Fujii,
H. Nishibata, K. Ieki, D. Murai, S. Momota, D. Nishimura, Y. Sato, J. Hwang, S. Kim, O. B. Tarasov, D. J. Morrissey, G. Simpson,“Identification of new neutron-rich isotopes in the rare-earth region produced by 345 MeV/nucleon 238 U,” J. Phys. Soc. Jpn. 87, 014202(2018).*
Y. Shimizu, T. Kubo, N. Fukuda, N. Inabe, D. Kameda, H. Sato, H. Suzuki, H. Takeda, K. Yoshida, G. Lorusso, H. Watanabe, G. S. Simpson, A. Jungclaus, H. Baba, F. Browne, P. Doornenbal, G. Gey, T. Isobe, Z. Li, S. Nishimura, P. Söderström, T. Sumikama, J. Taprogge,
Z. Vajta, J. Wu, Z. Xu, A. Odahara, A. Yagi, H. Nishibata, R. Lozeva, C. Moon, H. Jung, “Observation of new neutron-rich isotopes
among fission fragments from in-flight fission of 345 MeV/nucleon 238 U: Search for new isotopes conducted concurrently with decay
measurement campaigns,” J. Phys. Soc. Jpn. 87, 014203 (2018).*
S. Noji, H. Sakai, N. Aoi, H. Baba, G. P. A. Berg, P. Doornenbal, M. Dozono, N. Fukuda, N. Inabe, D. Kameda, T. Kawabata, S. Kawase,
Y. Kikuchi, K. Kisamori, T. Kubo, Y. Maeda, H. Matsubara, S. Michimasa, K. Miki, H. Miya, H. Miyasako, S. Sakaguchi, Y. Sasamoto,S. Shimoura, M. Takaki, H. Takeda, S. Takeuchi, H. Tokieda, T. Ohnishi, S. Ota, T. Uesaka, H. Wang, K. Yako, Y. Yanagisawa,
N. Yokota, K. Yoshida, R. G. T. Zegers, “Excitation of the isovector spin monopole resonance via the exothermic 90 Zr(12 N, 12 C)
reaction at 175 MeV/nucleon,” Phys. Rev. Lett. 120, 172501 (2018).*
O. B. Tarasov, D. S. Ahn, D. Bazin, N. Fukuda, A. Gade, M. Hausmann, N. Inabe, S. Ishikawa, N. Iwasa, K. Kawata, T. Komatsubara,
T. Kubo, K. Kusaka, D. J. Morrissey, M. Ohtake, H. Otsu, M. Portillo, T. Sakakibara, H. Sakurai, H. Sato, B. M. Sherrill, Y. Shimizu,
A. Stolz, T. Sumikama, H. Suzuki, H. Takeda, M. Thoennessen, H. Ueno, Y. Yanagisawa, K. Yoshida, “Discovery of 60 Ca and implications for the stability of 70 Ca,” Phys. Rev. Lett. 121, 022501 (2018).*
S. Michimasa, M. Kobayashi, Y. Kiyokawa, S. Ota, D. S. Ahn, H. Baba, G. P. A. Berg, M. Dozono, N. Fukuda, T. Furuno, E. Ideguchi,
N. Inabe, T. Kawabata, S. Kawase, K. Kisamori, K. Kobayashi, T. Kubo, Y. Kubota, C. S. Lee, M. Matsushita, H. Miya, A. Mizukami,
H. Nagakura, D. Nishimura, H. Oikawa, H. Sakai, Y. Shimizu, A. Stolz, H. Suzuki, M. Takaki, H. Takeda, S. Takeuchi, H. Tokieda,
T. Uesaka, K. Yako, Y. Yamaguchi, Y. Yanagisawa, R. Yokoyama, K. Yoshida, S. Shimoura, “Magic nature of neutrons in 54 Ca: First
mass measurements of 55–57 Ca,” Phys. Rev. Lett. 121, 022506 (2018).*
J. Yasuda, M. Sasano, R. G. T. Zegers, H. Baba, D. Bazin, W. Chao, M. Dozono, N. Fukuda, N. Inabe, T. Isobe, G. Jhang, D. Kameda,
M. Kaneko, K. Kisamori, M. Kobayashi, N. Kobayashi, T. Kobayashi, S. Koyama, Y. Kondo, A. J. Krasznahorkay, T. Kubo, Y. Kubota,
M. Kurata-Nishimura, C. S. Lee, J. W. Lee, Y. Matsuda, E. Milman, S. Michimasa, T. Motobayashi, D. Muecher, T. Murakami,
T. Nakamura, N. Nakatsuka, S. Ota, H. Otsu, V. Panin, W. Powell, S. Reichert, S. Sakaguchi, H. Sakai, M. Sako, H. Sato, Y. Shimizu,
M. Shikata, S. Shimoura, L. Stuhl, T. Sumikama, H. Suzuki, S. Tangwancharoen, M. Takaki, H. Takeda, T. Tako, Y. Togano, H. Tokieda,
J. Tsubota, T. Uesaka, T. Wakasa, K. Yako, K. Yoneda, J. Zenihiro, “Extraction of the Landau-Migdal parameter from the Gamow-Teller
giant resonance in 132 Sn,” Phys. Rev. Lett. 121, 132501 (2018).*
S. Leblond, F. M. Marqúes, J. Gibelin, N. A. Orr, Y. Kondo, T. Nakamura, J. Bonnard, N. Michel, N. L. Achouri, T. Aumann, H. Baba,
F. Delaunay, Q. Deshayes, P. Doornenbal, N. Fukuda, J. W. Hwang, N. Inabe, T. Isobe, D. Kameda, D. Kanno, S. Kim, N. Kobayashi,
T. Kobayashi, T. Kubo, J. Lee, R. Minakata, T. Motobayashi, D. Murai, T. Murakami, K. Muto, T. Nakashima, N. Nakatsuka, A. Navin,
S. Nishi, S. Ogoshi, H. Otsu, H. Sato, Y. Satou, Y. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, Y. Togano,A. G. Tuﬀ, M. Vandebrouck, K. Yoneda, “First observation of 20 B and 21 B,” Phys. Rev. Lett. 121, 262502 (2018).*
J. Park, R. Krucken, D. Lubos, R. Gernhauser, M. Lewitowicz, S. Nishimura, D. S. Ahn, H. Baba, B. Blank, A. Blazhev, P. Boutachkov,
F. Browne, I. Celikovic, G. de France, P. Doornenbal, T. Faestermann, Y. Fang, N. Fukuda, J. Giovinazzo, N. Goel, M. Gorska,
H. Grawe, S. Ilieva, N. Inabe, T. Isobe, A. Jungclaus, D. Kameda, G. D. Kim, Y. -K. Kim, I. Kojouharov, T. Kubo, N. Kurz, G. Lorusso,
K. Moschner, D. Murai, I. Nishizuka, Z. Patel, M. M. Rajabali, S. Rice, H. Sakurai, H. Schaﬀner, Y. Shimizu, L. Sinclair, P. -A. Soderstrom, K. Steiger, T. Sumikama, H. Suzuki, H. Takeda, Z. Wang, H. Watanabe, J. Wu, Z. Y. Xu, “β decays of the heaviest N = Z − 1nuclei and proton instability of 97 In,” Phys. Rev. C 97, 051301R (2018).*
J. L. Tain, J. Agramunt, D. S. Ahn, A. Algora, J. M. Allmond, H. Baba, S. Bae, N. T. Brewer, R. Caballero-Folch, F. Calvino, P. J. 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, G. G. Kiss, M. Kogimtzis, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, J. Lee,
J. Liu, G. Lorusso, K. Matsui, K. Miernik, F. Montes, B. Moon, A. I. Morales, N. Nepal, S. Nishimura, R. D. Page, Z. Podolyak,
V. F. E. Pucknell, B. C. Rasco, P. H. Regan, A. Riego, B. Rubio, K. P. Rykaczewski, Y. Saito, H. Sakurai, Y. Shimizu, J. Simpson,
P. A. Soderstrom, D. W. Stracener, T. Sumikama, R. Surman, H. Suzuki, M. Takechi, H. Takeda, A. Tarifeno-Saldivia, S. L. Thomas,
A. Tolosa-Delgado, V. H. Phong, P. Woods, “The BRIKEN project: Extensive measurements of β-delayed neutron emitters for the
astrophysical r process,” Acta Phys. Pol. B 49, 417 (2018).*
O. Wieland, A. Bracco, F. Camera, R. Avigo, H. Baba, N. Nakatsuka, T. Aumann, S. R. Banerjee, G. Benzoni, K. Boretzky, C. Caesar,- 330 -

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S. Ceruti, S. Chen, F. C. L. Crespi, V. Derya, P. Doornenbal, N. Fukuda, A. Giaz, K. Ieki, N. Kobayashi, Y. Kondo, S. Koyama, T. Kubo,
M. Matsushita, B. Million, T. Motobayashi, T. Nakamura, M. Nishimura, H. Otsu, T. Ozaki, A. T. Saito, H. Sakurai, H. Scheit,
F. Schindler, P. Schrock, Y. Shiga, M. Shikata, S. Shimoura, D. Steppenbeck, T. Sumikama, S. Takeuchi, R. Taniuchi, Y. Togano,
J. Tscheuschner, J. Tsubota, H. Wang, K. Wimmer, K. Yoneda, “Low-lying dipole response in the unstable 70 Ni nucleus,” Phys. Rev. C
98, 064313 (2018). *R. Yokoyama, E. Ideguchi, G. S. Simpson, Mn.Tanaka, S. Nishimura, P. Doornenbal, G. Lorusso, P. -A. Söderström, T. Sumikama,J. Wu, Z. Y. Xu, N. Aoi, H. Baba, F. L. Bello Garrote, G. Benzoni, F. Browne, R. Daido, Y. Fang, N. Fukuda, A. Gottardo, G. Gey,
S. Go, N. Inabe, T. Isobe, D. Kameda, K. Kobayashi, M. Kobayashi, I. Kojouharov, T. Komatsubara, T. Kubo, N. Kurz, I. Kuti,
Z. Li, M. Matsushita, S. Michimasa, C. B. Moon, H. Nishibata, I. Nishizuka, A. Odahara, Z. Patel, S. Rice, E. Sahin, H. Sakurai,
H. Schaﬀner, L. Sinclair, H. Suzuki, H. Takeda, J. Taprogge, Zs. Vajta, H. Watanabe, A. Yagi, T. Inakura, “Beta-gamma spectroscopyof the neutron-rich 150 Ba,” Prog. Theor. Exp. Phys. 2018, 041D02 (2018).*[Proceedings](Original Papers) *Subject to Peer Review
K. Kusaka, M. Ohtake, K. Yoshida, K. Tanaka, H. Mukai, Y. Uwamino, T. Kubo, “Radiation eﬀects in superconducting quadrupoles for
BigRIPS in-flight separator at RIKEN,” IEEE Trans. Appl. Supercond. 28, 1 (2018).*[Other]෱ా௚थ, ʮ73 छͷ৽ RI Λൃ‫—ݟ‬RIBF ͰՃ଎͢Δະ౿ͷ‫ੈ֩ࢠݪ‬քͷ։୓—ʯ, Isotope News 759(2018 ೥ 10 ݄߸), 22 (2018).

Oral Presentations[International Conference etc.]
N. Fukuda, “Present status of RI-beam production at BigRIPS: Search for new isotopes and nuclear drip lines, and measurement of
production cross sections,” EURORIB 2018, Giens, France, May 27–June 1, 2018.
D. S. Ahn, “Discovery of the 39 Na nuclide, the most neutron-rich Na isotope (N = 28) with the BigRIPS in-flight separator,” Nuclear
Structure 2018 Michigan State University, East Lansing, Michigan, USA, August 5–10, 2018.
K. Kusaka, “Long term operation of the superconducting triplet quadrupoles with cryocoolers for BigRIPS in-flight separator at RIKEN,”
27th International Cryogenics Engineering Conference (ICEC27-ICMC 2018), Oxford, UK, September 3–7, 2018.
N. Fukuda, “Production of new isotopes and search for neutron drip line with the BigRIPS separator at RIKEN RI Beam Factory,” IX
International Symposium on Exotic Nuclei (EXON2018), Petrozavodsk, Russia, September 10–15, 2018.
H. Takeda, “New ion-optical modes of the BigRIPS and ZeroDegree Spectrometer for the production of high-quality RI beams,” International Conference on ElectroMagnetic Isotope Separators and Related Topics (EMIS2018), CERN, Geneva, Switzerland, September
16–21, 2018.
Y. Yanagisawa, “Operational experience of the high-power production target system for BigRIPS separator,” The International Nuclear
Target Development Society (INTDS) Conference 2018, MSU/FRIB, East Lansing, Michigan, USA, October 8–12, 2018.
K. Yoshida, “Thermal model simulation of the high power target system for BigRIPS separator,” The International Nuclear Target Development Society (INTDS) Conference 2018, MSU/FRIB, East Lansing, Michigan, USA, October 8–12, 2018.
H. Suzuki, “Production of very neutron-rich Pd isotopes around N = 82 by projectile fragmentation of a RI beam of 132 Sn at 280 MeV/u,”
Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27(2018).
N. Fukuda, “Present status of RI-beam production at BigRIPS separator,” The 10th China-Japan Joint Nuclear Physics Symposium,
Huizhou, China, November 18–23, 2018.

[Domestic Conference]੢ོത, D. S. Ahn, G. P. A. Berg, ಊԂণഢ, ౻Ԭ޺೭, ෱ా௚थ, ෱੢ெঘ, H. Geissel, E. Haettner, ‫ڮ‬ຊ௚, ૣ໺ཾ‫ޒ‬, ൺ࿈࡚‫ޛ‬, ງҪ‫ࢤܒ‬, ஑໺ͳͭඒ, Ҵลঘਓ, ൘‫݈ڮ‬ଠ, ҏ౻੟, ‫࡚ؠ‬խ඙, ُాେี, ઒੉ᰌҰ࿠, ໦ࠤ৿‫ܚ‬Ұ, ਗ਼઒༟, ‫ٱ‬อහ޾, ೔Լ݈༞, দ‫ݪ‬ྱ໌, দԼণ࢙, ಓਖ਼৽Ұ࿠, ࡾ໦‫ݠ‬ೋ࿠, ࡾౢ߶, ‫ٶ‬༟೭, ଜҪେ஍, ଜ্༸ฏ, Ӭኍलࢠ, தଜ༞‫ت‬, ৽૔ , ໺஍ढ़ฏ, େՏ಺ެଠ,େా৾ี, ࡔຊ੒඙, ؔ‫ޱ‬ਔࢠ, ླ໦޺, ླ໦‫ݠ‬, ߴ໦‫ج‬৳, ஛ాߒ೭, ాதྑथ, ߾޸Ұ, ௩ా‫ڿ‬, ্ࡔ༑༸, ౉ลचҎ, Helmut Weick,ࢁా༟೭, ࢁ্େ‫و‬, ༄ᖒળߦ, ٢ాޫҰ, ʮཧԽֶ‫͚͓ʹॴڀݚ‬Δ (d, 3 He) ൓ԠΛ༻͍ͨύΠதؒࢠ‫ࢠݪ‬ͷ෼ޫ࣮‫ݧ‬ʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ ʢ2018 ೥ʣ, ౦‫ژ‬ཧՊେֶʢ໺ాΩϟϯύεʣ, ઍ༿, 2018 ೥ 3 ݄ 22–25 ೔.
෱ా௚थ, ਗ਼ਫཅฏ, ླ໦޺, A. H. N. DeukSoon, ஛ాߒ೭, ୸‫ה‬૱೭, ‫ٶ‬෢Ӊ໵, ౉ล༟, Ҵลঘਓ, ੢ଜढ़ೋ, େ௡ल‫ڿ‬, ٢ాޫҰ,্໺लथ, ࠤ౻޿ւ, ླ໦େհ, ࡫໺‫لڡ‬, ү෦஧ত, ฏࢁլҰ, Ո৓࿨෉, ఱ໺ॱ‫و‬, ʮ238 U ͷೖࣹ֩ഁࡅ൓ԠΛ༻͍ͨ N = 126ۙ๣ͷதੑࢠա৒֩ͷੜ੒ʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ ʢ2018 ೥ʣ, ౦‫ژ‬ཧՊେֶʢ໺ాΩϟϯύεʣ, ઍ༿, 2018 ೥ 3 ݄
22–25 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 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

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
H. N. Liu, A. Obertelli et al., “How robust is the N = 34 subshell closure? First spectroscopy of 52 Ar,” Phys. Rev. Lett. 122, 072502(2019).
S. Takeuchi, T. Nakamura et al., “Coulomb breakup reactions of 93, 94Zr in inverse kinematics,” Prog. Theor. Exp. Phys. 2019, 013D02(2019).
S. Leblond, M. Marques et al., “First observation of 20 B and 21 B,” Phys. Rev. Lett. 121, 262502 (2018).
S. Chebotaryov et al., “Proton elastic scattering at 200 A MeV and high momentum transfers of 1.7–2.7 fm−1 as a probe of the nuclear
matter density of 6 He,” Prog. Theor. Exp. Phys. 2018, 5, 1, 053D01 (2018).
J. Yasuda, M. Sasano et al., “Extraction of the Landau-Migdal parameter from the Gamow-Teller giant resonance in 132 Sn,” Phys. Rev.
Lett. 121, 132501 (2018).
T. Isobe et al., “Application of the Generic Electronics for Time Projection Chamber (GET) readout system for heavy Radioactive isotope
collision experiments,” Nucl. Instrum. Methods Phys. Res. A 899, 43 (2018).

Oral Presentations[International Conference etc.]
H. Otsu, “Invariant mass spectroscopy of neutron-rich nuclei with large acceptance spectrometer SAMURAI,” Fifth Joint Meeting of the
Nuclear Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Isobe, “Performance of SPiRIT-TPC with GET readout system for heavy ion collision experiment,” Workshop on Active Targets andTime Projection Chambers for High-intensity and Heavy-ion beams in Nuclear Physics, Santiago de Compostela, Spain, January 17–19,
2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

B. Tsang, “Highlights of the SpiRIT Time Projection Chamber, Workshop on Active Targets and Time Projection Chambers for Highintensity and Heavy-ion beams in Nuclear Physics,” Santiago de Compostela, Spain, January 17–19, 2018.
J. Estee, “Extending Dynamic Range, Calculating and Calibrating dE/dx in the SPiRIT TPC,” Workshop on Active Targets and Time
Projection Chambers for High-intensity and Heavy-ion beams in Nuclear Physics, Santiago de Compostela, Spain, January 17–19,
2018.
G. Jhang, “An overview of the analysis software for SPiRIT experiments,” Workshop on Active Targets and Time Projection Chambersfor High-intensity and Heavy-ion beams in Nuclear Physics, Santiago de Compostela, Spain, January 17–19, 2018.
T. Isobe, “The SPiRIT and pion detectors in RIKEN for the experimental study of symmetry energy with heavy ion collisions,” International Workshop on Multi facets of Eos and Clustering IWM-EC 2018, Catania, Italy, May 22–25, 2018.
T. Isobe, “Implementation of GET readout system for heavy RI collision experiment with SPiRIT-TPC at RIBF,” GET WORKSHOP:
General Electronic for Physics, Université de Bordeaux, France, October 10–12, 2018.
T. Isobe, “Experimental study of density dependent symmetry energy at RIBF-SPiRIT experiment,” Fifth Joint Meeting of the Nuclear
Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Isobe, “Study of density dependent asymmetric nuclear EOS by using heavy RI collisions at RIKEN-RIBF,” 52nd Reimei Workshop,
Experimental and Theoretical Hadron Physics: Recent Exciting Developments, Tokai, Japan, Jan 9–11, 2019.
M. Kurata-Nishimura, “SPiRIT-TPC experiment with neutron rich Sn + Sn collisions in RIKEN-RIBF,” Fifth Joint Meeting of the Nuclear
Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
M. Kaneko, “Study of light cluster production in intermediate energetic heavy-RI collision at RIBF,” Fifth Joint Meeting of the Nuclear
Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
W. G. Lynch, “Present and expected constraints on the Nuclear Symmetry Energy,” 8th International Symposium on Nuclear Symmetry
Energy (NuSYM2018), Busan, South Korea, September 10–13, 2018.
M. Kurata-Nishimura, “Collective flow at neutron rich Sn + Sn collisions with 270 MeV/u,” 8th International Symposium on Nuclear
Symmetry Energy (NuSYM2018), Busan, South Korea, September 10–13, 2018.
G. Ghang, “Recent results on pion analysis of Sn + Sn collisions,” 8th International Symposium on Nuclear Symmetry Energy(NuSYM2018), Busan, South Korea, September 10–13, 2018.
M. Kaneko, “Study of light cluster production in intermediate energetic heavy-RI collision at RIBF,” 8th International Symposium on
Nuclear Symmetry Energy (NuSYM2018), Busan, South Korea, September 10–13, 2018.
R. Wang, “Quality assurance for TPC data analysis of intermediate energy heavy ion collisions,” 8th International Symposium on Nuclear
Symmetry Energy (NuSYM2018), Busan, South Korea, September 10–13, 2018.
J. W. Lee, “Charged particle track reconstruction for heavy ion collision experiments with SπRIT Time Projection Chamber,” 8th International Symposium on Nuclear Symmetry Energy (NuSYM2018), Busan, South Korea, September 10–13, 2018.
M. Kaneko, “Study of light cluster production in intermediate energetic heavy-RI collision at RIBF,” 8th International Symposium on
Nuclear Symmetry Energy (NuSYM2018), Busan, South Korea, September 10–13, 2018.
T. Murakami, “Probing Nuclear Symmetry Energy at high densities with SpRIT-TPC,” The 20th Northeastern Asia Symposium, Nagoya,Japan, September 19–20, 2018.
T. Murakami, “Experiments Probing Nuclear Symmetry Energy at Supra-Saturation Densities,” Nucleus-Nucleus Collisions (NN2018),
Saitama, Japan, December 4–8, 2018.
W. G. Lynch, “Probing the Equation of State of Neutron-rich Matter,” Nucleus-Nucleus Collisions (NN2018), Saitama, Japan, December
4–8, 2018.
M. Kaneko, “Study of light cluster production in intermediate energetic heavy-RI collision at RIBF,” Nucleus-Nucleus Collisions(NN2018), Saitama, Japan, December 4–8, 2018.
M. Kurata-Nishimura, “Collective flow at neutron rich Sn + Sn collisions with 270 MeV/nucleon,” Nucleus-Nucleus Collisions (NN2018),
Saitama, Japan, December 4–8, 2018.
T. Nakamura, “Multi-neutron clusters in neutron-rich nuclei,” Workshop on Clusters in Quantum Systems: from Atoms to Nuclei and
Hadrons, Sendai, Japan, January 28–February 1, 2019.
T. Nakamura, “Exploring towards the neutron-rich limit of nuclei, and beyond,” 57th International Winter Meeting on Nuclear Physics,
Bormio Italy, January 21–25, 2019.
T. Nakamura, “Breakup reactions of neutron-rich nuclei for application to stellar reactions,” ECT* Workshop on “Indirect Methods in
Nuclear Astrophysics,” Trento, Italy, November 5–9, 2018.
T. Nakamura, “Exploration towards the nuclear limit: neutron drip line and beyond,” Fifth Joint Meeting of the Nuclear Physics Divisionsof the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Nakamura, “Exploration around and beyond the limit of nuclear stability: Exotic structure and reactions,” 5th Tokyo Tech-Uppsala
University Joint Symposium, Uppsala, Sweden, September 24–25, 2018.
T. Nakamura, “Clustering as a window on the hierarchical structure of quantum systems,” SAMURAI International Collaboration Workshop, RIKEN, Japan, September 5–6, 2018.
T. Nakamura, “Recent Experiments and Perspectives of SAMURAI,” RIBF Users meeting 2018, Wako, Japan, September 5–6, 2018.
T. Nakamura, “Exploration of extremes of nuclei at SAMURAI at RIBF,” SFB1245 Workshop, Mainz, Germany, July 4–6, 2018.
T. Nakamura, “Search for multi-neutron clusters in unbound excited states of 10 He and 28 O,” SAMURAI International Collaboration
Workshop, RIKEN, Wako, Japan, September 5–6, 2018.
Y. Kondo, “Experimental study of neutron-rich oxygen isotopes beyond the drip line,” Nucleus-Nucleus Collisions (NN2018), Saitama,- 333 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)Japan, December 4–8, 2018.
Y. Kondo, “Recent progress and developments for experimental studies with the SAMURAI spectrometer,” Internationa Conference on
Electromagnetic Isotope Separator and Related Topics (EMIS2018), CERN, Geneva, Switzerland, September 16–21, 2018.
Y. Kondo, “Experimental studies of unbound neutron-rich nuclei,” XXII International Conference on Few-Body Problems in Physics(FB22), Caen, France, July 9–13, 2018.
Y. Kondo, “Study of the unbound nuclei 27 O and 28 O using proton removal reactions,” 10th International Conference on Direct Reactions
with Exotic Beams (DREB2018), Matsue, Japan, June 4–8, 2018.
T. Tomai, “Breakup reactions of one-neutron halo nucleus 31 Ne,” 10th International Conference on Direct Reactions with Exotic Beams(DREB2018), Matsue, Japan, June 4–8, 2018.
T. Tomai, “Coulomb breakup reaction of one neutron halo nucleus 31 Ne,” Nucleus-Nucleus Collisions (NN2018), Saitama, Japan, December 4–8, 2018.
M. Yasuda, “In-beam gamma-ray spectroscopy of 28–30 Ne,” Nucleus-Nucleus Collisions (NN2018), Saitama, Japan, December 4–8, 2018.
H. Miki, “Structure of 28 F studied by the (n, p) type charge-exchange reaction of 28 Ne,” Fifth Joint Meeting of the Nuclear Physics
Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Tomai, “Coulomb breakup reaction of 31 Ne and its halo structure,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS
and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
M. Yasuda, “In-beam gamma-ray spectroscopy of F and Ne isotopes near the island of inversion,” Fifth Joint Meeting of the Nuclear
Physics Divisions of the APS and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
T. Shimada, “Spectroscopy of the unbound neutron-rich nucleus 30 F,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS
and the JPS (HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
Y. Togano, “Matter radius of two-neutron halo nucleus 22 C,” NN2018, Saitama Japan, December 4–8, 2018.
Y. Togano, “New gamma-ray detector CATANA for in-bema gamma-ray spectroscopy with fast RI beams,” EMIS2018, Geneva Switzerland, September 16–21, 2018.
Y. Togano, “Studies of 22 C and 50, 52 Ca at SAMURAI,” EXON2018, Petrozavodsk Russia, September 10–15, 2018.
Y. Togano, “E1 responses of neutron-rich Ca isotopes 50 Ca and 52 Ca,” DREB2018, Matsue, Japan, June 4–8, 2018.
Y. Togano, “Electric dipole response of 50, 52 Ca,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS(HAWAII2018), Waikoloa, Hawaii, USA, October 23–27 (2018).
Y. Fujino, “Coulomb excitation of 52 Ca,” Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS (HAWAII2018),
Waikoloa, Hawaii, USA, October 23–27 (2018).
D. Beaumel, “Investigation of nuclear overlaps near the neutron dripline,” International Conference on Recent Issues in Nuclear andParticle Physics 2 Visva-Bharati, India, February 3–5, 2019.
D. Beaumel, “Nuclear overlaps near the neutron dripline,” International Workshop on “Clusters in Quantum Systems: from Atoms to
Nuclei and Hadrons,” Sendai, Japan, January 28–February 1, 2019.

[Domestic Conference]ү෦஧ত, ʮཧ‫ ݚ‬RIBF ʹ͓͚Δॏ RI িಥ࣮‫—༻ݧ‬λΠϜϓϩδΣΫγϣϯνϟϯόʔͷੑೳධՁʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
ࡾ໦੖ྤ, ʮՙిަ‫׵‬൓ԠΛ༻͍ͨதੑࢠա৒ඇଋറ֩ 28 F ͷ‫ڀݚ‬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
‫ݪ܀‬ಞࢤ, ʮ22 C ͷΫʔϩϯ෼ղ൓Ԡʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
ేถ‫و‬ਓ, ʮ֩ྗ෼ղ൓ԠΛ༻͍ͨ 31 Ne ͷྭ‫ى‬ঢ়ଶͷ୳ࡧʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.

[Domestic Conference]ү෦஧ত, ʮཧ‫ ݚ‬RIBF ʹ͓͚Δॏ RI িಥ࣮‫—༻ݧ‬λΠϜϓϩδΣΫγϣϯνϟϯόʔͷੑೳධՁʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
ࡾ໦੖ྤ, ʮՙిަ‫׵‬൓ԠΛ༻͍ͨதੑࢠա৒ඇଋറ֩ 28 F ͷ‫ڀݚ‬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
‫ݪ܀‬ಞࢤ, ʮ22 C ͷΫʔϩϯ෼ղ൓Ԡʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
ేถ‫و‬ਓ, ʮ֩ྗ෼ղ൓ԠΛ༻͍ͨ 31 Ne ͷྭ‫ى‬ঢ়ଶͷ୳ࡧʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.

Master Thesisࢁా‫وܒ‬, ʮதੑࢠա৒֩ 32 Ne ͷΠϯϏʔϜ γ ઢ෼ޫʯ, ౦‫ۀ޻ژ‬େֶཧֶӃ෺ཧֶ‫ܥ‬.
҆ాণ߂, ʮ‫ٯ‬సͷౡ‫ڥ‬ք֩ͷεϖΫτϩείϐʔʯ, ౦‫ۀ޻ژ‬େֶཧֶӃ෺ཧֶ‫ܥ‬.
দຊਅ༝ࢠ, ʮதੑࢠա৒֩ 32 Ne ͷඇଋറ४Ґͷ୳ࡧʯ, ౦‫ۀ޻ژ‬େֶཧֶӃ෺ཧֶ‫ܥ‬.

Bachelor Thesis٢ཹ༐‫ى‬, ʮඇଋറதੑࢠա৒֩෼ޫͷͨΊͷՙిަ‫׵‬൓Ԡͷ‫ڀݚ‬ʯ, ౦‫ۀ޻ژ‬େֶ.
҆ా੟, ʮμΠχϡʔτϩϯ୳ࡧͷͨΊͷߴਫ਼ࡉதੑࢠ‫ݕ‬ग़‫ث‬ͷ։ൃʯ, ౦‫ۀ޻ژ‬େֶ.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 has been successfully upgraded by
5 GTO modules. To improve the data readout speed of VME system, we are developing FPGA-based small VME controller named
as Mountable-Controller (MOCO). This controller can be attached to each ADC/TDC VME module. Usually, in the VME system,
one master controller readout data from all modules in the VME shelf. On the other hand, data readout is carried out in parallel bymultiple MOCO boards even ADC/TDC modules are in the same VME shelf. To establish robust MOCO-based VME system, we
have developed MOCO with Parallelized VME (MPV) system which is a kind of the parallel readout extension of the VME bus. ThisMPV system merges data from multiple MOCOs and send it to the DAQ server.
(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, a 10 Gbps network- 335 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

port has been introduced to the RIBF Experimental area in for the high-speed data transfer of RIBF experiment to HOKUSAI.
Approximately 70 units of wireless LAN access points have been installed to cover the almost entire area of Nishina Center.
(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 (concurrent; Senior Research Scientist,
Radiation Lab.)
Junior Research Associates
Fumiya GOTO (Nagoya Univ.)
Special Temporary Employee
Takashi ICHIHARA (concurrent; Special Temporary Employee, RI Physics Lab.)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
A. Tolosa-Delgado et al., “Commissioning of the BRIKEN detector for the measurement of very exotic β-delayed neutron emitters,” Nucl.
Instrum. Methods Phys. Res. A 925, 133–147 (2019).
C. Santamaria et al., “Tracking with the MINOS time projection chamber,” Nucl. Instrum. Methods Phys. Res. A 905, 138–148 (2018).
T. Isobe et al., “Application of the Generic Electronics for Time Projection Chamber (GET) readout system for heavy radioactive isotope
collision experiments,” Nucl. Instrum. Methods Phys. Res. A 899, 43–48 (2018).
E. C. Pollacco et al., “GET: A generic electronics system for TPCs and nuclear physics instrumentation,” Nucl. Instrum. Methods Phys.
Res. A 887, 81–93 (2018).

Oral Presentations[International Conference etc.]
H. Baba, “Parallel read-out extension of the VME DAQ system,” 5th Joint Meeting of the APS Division of Nuclear Physics and the
Physical Society of Japan, Waikoloa Village, HI, USA, October 23–27, 2018.

Posters Presentations[International Conference etc.]
H. Baba, “Prototype of a multi-host type DAQ front-end system for RI-beam experiments,” 21th IEEE Real Time Conference, Colonial
Williamsburg, VA, USA, June 9–15, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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)

Mayuka IKEKAME (Toho University)
Yuka HIKIMA (Toho Universicy)
Mitsumasa MORI (Toho University)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
Y. Hashimoto, H. H. Huang, M. Yoshimura, M. Hara, T. Hara, Y. Hara, M. Hamagaki, “Dependence on treatment ion energy of nitrogenplasma for oxygen reduction reaction of high ordered pyrolytic graphite,” Jpn. J. Appl. Phys. 57, 125504 (2018). *O. B. Tarasov, D. S. Ahn, D. Bazin, N. Fukuda, A. Gade, M. Hausmann, N. Inabe, S. Ishikawa, N. Iwasa, K. Kawata, T. Komatsubara,
T. Kubo, K. Kusaka, D. J. Morrissey, M. Ohtake, H. Otsu, M. Portillo, T. Sakakibara, H. Sakurai, H. Sato, B. M. Sherrill, Y. Shimizu,
A. Stolz, T. Sumikama, H. Suzuki, H. Takeda, M. Thoennessen, H. Ueno, Y. Yanagisawa, K. Yoshida, “Discovery of 60 Ca and Implications For the Stability of 70 Ca,” Phys. Rev. Lett. 121, 022501 (2018). *S. Chebotaryov, S. Sakaguchi, T. Uesaka, T. Akieda, Y. Ando, M. Assie, D. Beaumel, N. Chiga, M. Dozono, A. Galindo-Uribarri,
B. Heﬀron, A. Hirayama, T. Isobe, K. Kaki, S. Kawase, W. Kim, T. Kobayashi, H. Kon, Y. Kondo, Y. Kubota1, S. Leblond, H. Lee,
T. Lokotko, Y. Maeda, Y. Matsuda, K. Miki, E. Milman, T. Motobayashi, T. Mukai, S. Nakai, T. Nakamura, A. Ni, T. Noro, S. Ota,
H. Otsu, T. Ozaki, V. Panin, S. Park, A. Saito, H. Sakai, M. Sasano, H. Sato, K. Sekiguchi, Y. Shimizu, I. Stefan, L. Stuhl, M. Takaki,
K. Taniue, K. Tateishi, S. Terashima, Y. Togano, T. Tomai, Y. Wada, T. Wakasa, T. Wakui, A. Watanabe, H. Yamada, Zh. Yang,
M. Yasuda, J. Yasuda, K. Yoneda, J. Zenihiro, “Proton elastic scattering at 200 AMeV and high momentum transfers of 1.7–2.7 fm−1
as a probe of the nuclear matter density of 6 He,” Prog. Theor. Exp. Phys. Issue 053D01 (2018). *S. Leblond, F. M. Marques, J. Gibelin, N. A. Orr, Y. Kondo, T. Nakamura, J. Bonnard, N. Michel, N. L. Achouri, T. Aumann, H. Baba,
F. Delaunay, Q. Deshayes, P. Doornenbal, N. Fukuda, J. W. Hwang, N. Inabe, T. Isobe, D. Kameda, D. Kanno, S. Kim, N. Kobayashi,
T. Kobayashi, T. Kubo, J. Lee, R. Minakata, T. Motobayashi, D. Murai, T. Murakami, K. Muto, T. Nakashima, N. Nakatsuka, A. Navin,
S. Nishi, S. Ogoshi, H. Otsu, H. Sato, Y. Satou, Y. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, Y. Togano,A. G. Tuﬀ, M. Vandebrouck, K. Yoneda, “First observation of 20 B and 21 B,” Phys. Rev. Lett. 121, 262502 (2018). *- 337 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

J. Yasuda, M. Sasano, R. G. T. Zegers, H. Baba, D. Bazin, W. Chao, M. Dozono, N. Fukuda, N. Inabe, T. Isobe, G. Jhang, D. Kameda,
M. Kaneko, K. Kisamori, M. Kobayashi, N. Kobayashi, T. Kobayashi, S. Koyama, Y. Kondo, A. J. Krasznahorkay, T. Kubo, Y. Kubota,
M. Kurata-Nishimura, C. S. Lee, J. W. Lee, Y. Matsuda, E. Milman, S. Michimasa, T. Motobayashi, D. Muecher, T. Murakami,
T. Nakamura, N. Nakatsuka, S. Ota, H. Otsu, V. Panin, W. Powell, S. Reichert, S. Sakaguchi, H. Sakai, M. Sako, H. Sato, Y. Shimizu,
M. Shikata, S. Shimoura, L. Stuhl, T. Sumikama, H. Suzuki, S. Tangwancharoen, M. Takaki, H. Takeda, T. Tako, Y. Togano, H. Tokieda,
J. Tsubota, T. Uesaka, T. Wakasa, K. Yako, K. Yoneda, J. Zenihiro, “Extraction of the Landau-Migdal parameter from the Gamow-Teller
giant resonance in 132 Sn,” Phys. Rev. Lett. 121, 132501 (2018). *Oral Presentations[International Conference etc.]
T. Ikeda, “Transmission of keV and MeV ions through glass capillary for microbeam engineering,” 1st Mini-Workshop for Physics of Ions:
Frontiers and Applications/Symposium on Physics and Applications of Ion Beams, (Lanzhou University), Lanzhou, Gansu, China, July
2018.

[Domestic Conference]஑ా࣌ߒ, ඿ֶ֞, ࠤ౻޿ւ, ʮཧԽֶ‫͚͓ʹॴڀݚ‬ΔλϯσϜՃ଎‫ث‬ͷ‫ݱ‬ঢ়ʢ2017–2018 ೥౓ʣʯ, ୈ 31 ճʮλϯσϜՃ଎‫ͼٴث‬ͦͷपลٕज़ͷ‫ڀݚ‬ձʯ, ʢ౦‫ࢢ౎ژ‬େֶʣ, ౦‫ాੈ౎ژ‬୩۠, 2018 ೥ 7 ݄.
஑ా࣌ߒ, ኍ੉‫࢜׮‬, ࠤ౻‫ݠ‬ଠ, ඿ֶ֞, Տଜढ़࠸, দ‫ॆݪ‬๕, ஑ُਅ༝Ղ, Ҿؒ༒Ֆ, ৿ޫਖ਼, ຳྠୡ࠸, ࠤ౻޿ւ, ۚӴࠃ, ʮΩϟϐϥϦʔޫֶ‫ʹܥ‬ΑΔϨʔβʔ͓ΑͼΠΦϯϚΠΫϩϏʔϜͷಉ࣌ੜ੒ʯ, ೔ຊ෺ཧֶձ 2018 ೥ळ‫ق‬େձ, ʢಉࢤࣾେֶʣ, ‫ాژ‬ลࢢ, 2018 ೥ 9 ݄.
ࠤ౻‫ݠ‬ଠ, ஑ా࣌ߒ, ኍ੉‫࢜׮‬, ޾ౡඒًࢠ, দ‫ॆݪ‬๕, ຳྠୡ࠸, ۚӴࠃ, ʮΩϟϐϥϦʔޫֶ‫ʹܥ‬ΑΔՄࢹޫϨʔβʔϚΠΫϩε
ϙοτͷߏ଄ධՁʯ, ೔ຊ෺ཧֶձ 2018 ೥ळ‫ق‬େձ,ʢಉࢤࣾେֶʣ, ‫ాژ‬ลࢢ, 2018 ೥ 9 ݄.
Տଜढ़࠸, ஑ా࣌ߒ, দ‫ॆݪ‬๕, ஑ُਅ༝Ղ, Ҿؒ༒Ֆ, ৿ޫਖ਼, ຳྠୡ࠸, ۚӴࠃ, ʮΩϟϐϥϦʔޫֶ‫ʹܥ‬ΑΔࢵ֎ઢϨʔβʔϚΠΫϩεϙοτϥΠτͷ։ൃʯ, ೔ຊ෺ཧֶձ 2018 ೥ळ‫ق‬େձ,ʢಉࢤࣾେֶʣ, ‫ాژ‬ลࢢ, 2018 ೥ 9 ݄.
஑ా࣌ߒ, ʮΨϥεΩϟϐϥϦʔʹΑΔϚΠΫϩϏʔϜͷੜ੒ͱԠ༻ʯ, ट౎େֶ౦‫ژ‬ԽֶՊୈ 287 ճԽֶίϩΩ΢Ϝ, ʢट౎େֶ
౦‫ژ‬ʣ, ീԦࢠࢢ, 2018 ೥ 9 ݄.
஑ా࣌ߒ, Ҿؒ༒Ֆ, ৿ޫਖ਼, ஑ُਅ༝Ղ, Տଜढ़࠸, দ‫ॆݪ‬๕, ຳྠୡ࠸, ۚӴࠃ, ʮΨϥεΩϟϐϥϦʔʹΑΔΠΦϯϚΠΫϩϏʔϜরࣹͰੜͨ͡ࡉ๔֩಺ΠΦϯτϥοΫͷղੳʯ, ୈ 61 ճ์ࣹઢԽֶ౼࿦ձ, ʢେࡕࢢཱେֶʣ, େࡕࢢ, 2018 ೥ 9 ݄.
஑ُਅ༝Ղ, ஑ా࣌ߒ, ৿ޫਖ਼, Ҿؒ༒Ֆ, Տଜढ़࠸, দ‫ॆݪ‬๕, ຳྠୡ࠸, ۚӴࠃ, ʮΨϥεΩϟϐϥϦʔʹΑΔϚϧνྔࢠϚΠΫϩϏʔϜরࣹʹ޲͚ͨΠΦϯϏʔϜϓϩϑΝΠϧଌఆʯ, ୈ 61 ճ์ࣹઢԽֶ౼࿦ձ,ʢେࡕࢢཱେֶʣ, େࡕࢢ, 2018 ೥ 9 ݄.
৿ޫਖ਼, ஑ా࣌ߒ, ஑ُਅ༝Ղ, Ҿؒ༒Ֆ, Տଜढ़࠸, দ‫ॆݪ‬๕, ຳྠୡ࠸, ۚӴࠃ, ʮΨϥεΩϟϐϥϦʔޫֶ‫ʹܥ‬ΑΔϚΠΫϩϨʔβʔϏʔϜϓϩϑΝΠϧͷଌఆɿඍখςΟϧτ֯ґଘੑʯ, ୈ 61 ճ์ࣹઢԽֶ౼࿦ձ,ʢେࡕࢢཱେֶʣ, େࡕࢢ, 2018 ೥ 9 ݄.
Ҿؒ༒Ֆ, ஑ా࣌ߒ, ৿ޫਖ਼, ஑ُਅ༝Ղ, Տଜढ़࠸, দ‫ॆݪ‬๕, ຳྠୡ࠸, ۚӴࠃ, ʮΨϥεΩϟϐϥϦʔޫֶ‫ʹܥ‬ΑΔࢵ֎ઢϚΠΫϩϏʔϜͷ‫ܗ‬ঢ়ଌఆɿϑΥτΫϩϛοΫγʔτΛ࢖ͬͨεϙοτసࣸʯ, ୈ 61 ճ์ࣹઢԽֶ౼࿦ձ,ʢେࡕࢢཱେֶʣ, େࡕࢢ,2018 ೥ 9 ݄.
Տଜढ़࠸, ஑ా࣌ߒ, ஑ُਅ༝Ղ, ৿ޫਖ਼, Ҿؒ༒Ֆ, দ‫ॆݪ‬๕, ຳྠୡ࠸, ۚӴࠃ, ʮࢵ֎ઢϚΠΫϩϏʔϜࡉ๔রࣹγεςϜͷ։ൃ:ඍখ‫Ͱ཭ڑ‬ͷϓϩϑΝΠϧଌఆͱΤωϧΪʔධՁʯ, ୈ 61 ճ์ࣹઢԽֶ౼࿦ձ,ʢେࡕࢢཱେֶʣ, େࡕࢢ, 2018 ೥ 9 ݄.
ᓎҪ੣, ੢ాঘ࢙, ງ݁‫ت‬, ࢁ಺ѥ߳Ի, ஑ా࣌ߒ, ʮΨϥεΩϟϐϥϦʔΛ༻͍ͨ ଟՁΠΦϯͷऩଋख๏ ʯ, 2018 ೥೔ຊද໘ਅۭ
ֶձֶज़ߨԋձ, ʢਆ‫ࡍࠃށ‬ձٞ৔ʣ, ਆ‫ࢢށ‬, 2018 ೥ 11 ݄.
஑ా࣌ߒ, ஑ُਅ༝Ղ, Ҿؒ༒Ֆ, ৿ޫਖ਼, Տଜढ़࠸, দ‫ॆݪ‬๕, ຳྠୡ࠸, ۚӴࠃ, ʮϑλ෇ΨϥεΩϟϐϥϦʔޫֶ‫Ͱܥ‬ੜ੒͞Εͨେ‫ؾ‬த MeV ΠΦϯϚΠΫϩϏʔϜͷϓϩϑΝΠϧଌఆʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ,ʢ‫۝‬भେֶʣ, ෱Ԭࢢ, 2019 ೥ 3 ݄.
ञҪխ࠸, ஑ా࣌ߒ, ҆Ҫ໌, ઍ༿ಸ௡ࢠ, ஛ຊ݈ਓ, ্ࡔॆ, ʮα ઢ࣏ྍͷͨΊͷ He ΠΦϯϚΠΫϩϏʔϜ DNA রࣹ෼ੳͷ‫ૅج‬‫ڀݚ‬ʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥य़ͷ೥ձ,ʢҵ৓େֶʣ, ਫ‫ࢢށ‬, 2019 ೥ 3 ݄.
஛ຊ݈ਓ, ʮϚΠΫϩϏʔϜΛ༻͍ͨ‫ॴہ‬తরࣹʹΑΔ DNA ଛইͷ 3 ࣍‫ݩ‬Ґஔ৘ใղੳʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥य़ͷ೥ձ,ʢҵ৓େֶʣ, ਫ‫ࢢށ‬, 2019 ೥ 3 ݄.

Posters Presentations[International Conference etc.]
K. Yokokawa, K. Takahashi, J. Matsumoto, H. Shiromaru, T. Ikeda, T. M. Kojima, “Current-dependent ion beam guiding by straight macro
capillaries,” 10th International Symposium on Swift Heavy Ions in Matter & 28th International Conference on Atomic Collisions in
Solids (SHIM-ICACS 2018), (Université Caen Normandie), Caen, France, July 2018.
T. Ikeda, T. Irimatsugawa, Y. Miura, N. Nakada, T. M. Kojima, I. Hakamada, N. Matsufuji, M. Sakama, M. Miwa, M. Ohno, “A transmission experiment of carbon ion beam of 100 MeV/nucleon through tapered glass tubes,” 10th International Symposium on Swift Heavy
Ions in Matter & 28th International Conference on Atomic Collisions in Solids (SHIM-ICACS 2018), (Université Caen Normandie),Caen, France, July, 2018.

[Domestic Conference]Տଜढ़࠸, ஑ా࣌ߒ, ࠤ౻‫ݠ‬ଠ, দ‫ॆݪ‬๕, ஑ُਅ༝Ղ, Ҿؒ༒Ֆ, ৿ޫਖ਼, ຳྠୡ࠸, ۚӴࠃ, ʮΨϥεΩϟϐϥϦʔޫֶ‫ʹܥ‬ΑΔΠΦϯɾϨʔβʔϚΠΫϩϏʔϜੜ੒ͱͦͷԠ༻ʯ, ୈ 39 ճ‫ࢠݪ‬িಥएखͷձ,ʢಸྑϢʔεϗεςϧʣ, ಸྑࢢ, 2018 ೥ 10 ݄.
஑ా࣌ߒ, ஑ُਅ༝Ղ, ৿ޫਖ਼, Ҿؒ༒Ֆ, Տଜढ़࠸, দ‫ॆݪ‬๕, ຳྠୡ࠸, ۚӴࠃ, ʮΨϥεΩϟϐϥϦʔͰੜ੒͞Εͨ MeV ΠΦϯϚΠΫϩϏʔϜ‫ܗ‬ঢ়ͷඍখςΟϧτ֯ґଘੑʯ, ‫ࢠݪ‬িಥֶձୈ 43 ճ೥ձ,ʢ‫౎ژ‬େֶʣ, Ӊ࣏ࢢ, 2018 ೥ 10 ݄.
ԣ઒‫و‬Ұ, ߴ‫ߤڮ‬େ, দຊ३, ৓‫ؙ‬य़෉, ஑ా࣌ߒ, খౡ ོ෉, ʮ௿଎ଟՁΠΦϯϏʔϜʹର͢ΔΨϥε௚؅ʹΑΔΨΠυޮՌʹ͓͚- 338 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)Δૉࡐ͝ͱͷϏʔϜిྲྀґଘੑʯ, ‫ࢠݪ‬িಥֶձୈ 43 ճ೥ձ,ʢ‫౎ژ‬େֶʣ, Ӊ࣏ࢢ, 2018 ೥ 10 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Accelerator Applications Research Division
Beam Mutagenesis Group
1. Abstract

This group promotes various 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. RI Applications Team studies production and application of radioisotopes for various research fields, development of trace element analysis andits application, and development of chemical materials for ECR ion sources of RIBF accelerators.

2. Major Research Subjects

Research and development in biology, chemistry and materials science utilizing heavy-ion beams from RI Beam Factory.

3. Summary of Research Activity
(1)
(2)
(3)
(4)
(5)
(6)
(7)

Biological eﬀects of fast heavy ions
Molecular nature of DNA alterations induced by heavy-ion irradiation
Research and development of heavy-ion breeding
RI application researches
Research and development of RI production technology at RIBF
Developments of trace elements analyses
Development of chemical materials for ECR ion sources of RIBF accelerators

Members
Group Director
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. 52 (2019)

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 physiological study of DNA repair, genome analyses of mutation, and development of mutation breeding of plants byheavy-ion irradiation. Some new cultivars 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). It is well known to be good for cancer
therapy to adjust the BP to target malignant cells. On the other hand, a uniform dose distribution is a key to the systematic study
for heavy-ion mutagenesis, and thus to the improvement of the mutation eﬃciency. Therefore plants and microbes are treated 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. The most eﬀective LET (LETmax) was 30 keV/µm. LETmax irradiations showed the same
mutation rate as that by chemical mutagens, which typically cause high mutation rate. The LETmax of imbibed rice (Oryza sativa L.)
seeds, dry rice seeds and dry wheat (Triticum monococcum) seeds were shown to be 50–63 keV/µm, 23–30 keV/µm and 50 keV/µm,
respectively. In the case of microbe (Mesorhizobium lothi), the results showed a higher incidence of deletion mutations for Fe ions at
640 keV/µm than for C ions at 23–40 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
Detailed analyses on the molecular nature of DNA alterations have been reported as an LET-dependent eﬀect for induced mutation.
The most mutations were deletions ranging from a few to several tens of base pairs (bp) in the Arabidpsis thaliana mutants inducedby irradiation with C ions at 30 keV/µm and rice mutants induced by irradiation with C ions at 50 keV/µm or Ne ions at 63 keV/µm.
LETmax is eﬀective for breeding because of its very high mutation frequency. Since most mutations are small deletions, these are
suﬃcient to disrupt 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 290 keV/µm showed a mutation spectrum diﬀerent from that at
LETmax: the proportion of small deletions (<1 kbp) was low, while that of large deletions ranging from several to several tens ofkbp, and rearrangements was high. Many genes in the genome (>10%) are composed of tandem duplicated genes that share functions.
For knockout of the tandem duplicated genes, large deletions are required, and the appropriate deletion size is estimated to be around
5–10 kbp and 10–20 kbp based on the gene density in Arabidpsis and rice, respectively. No method is currently available to eﬃciently
generate deletion mutants of this size. 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
We have formed a consortium for ion-beam breeding. It consisted of 24 groups in 1999, in 2018, it consisted of 180 groups fromJapan and 17 from overseas. Breeding was performed previously using mainly flowers and ornamental plants. We have recently put
a new sweet-smelling onion cultivar with tearless and non-pungent, ‘Smile Balls’ on the market. Beneficial variants have been grown
for various plant species, such as high yield rice, semi-dwarf early rice, semi-dwarf buckwheat, semi-dwarf barley, hypoallergenic
peanut, spineless oranges, non-flowering Eucalyptus and lipids-hyperaccumulating unicellular alga. The target of heavy-ion breeding
is extended from flowers to crops so that it will contribute to solve the global problems of food and environment. We collaborate
with the National Research and Development Agency, Japan Fisheries Research and Education Agency and Nagasaki University. The
monogonont rotifer (Brachionus spp.) is a complex species and an essential food source for finfish aquaculture. The B. plicatilis
is divided into three major clades (small, medium and large (L)) based on body length. Although the body size ranges from 100- 341 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

to 300 µm in length, a mutation breeding of rotifers with larger size is expected for the purpose of productivity improvement in theaquaculture industry. Therefore, we conducted a large-scale screening to isolate gigantic rotifers by heavy-ion-beam irradiation to
L-type rotifers. Then we have established 23 mutant lines that have an average length of over 350 µm (a maximum length reached
404 µm) through over ten thousand of individual mutagenized lines. These data will be useful to choose the suitable lines that satisfies
the request of the aquaculture industry.

Members
Team Leader
Tomoko ABE (concurrent: Group Director, Accelerator Applications Research Gr.)
Research/Technical Scientists
Kazuhide TSUNEIZUMI (Senior Research Scientist)
Masako IZUMI (Senior Research Scientist)
Teruyo TSUKADA (Senior Research Scientist)
Katsunori ICHINOSE (Senior Technical Scientist)

Tokihiro IKEDA (concurrent)
Hiroshi ABE (Senior Technical Scientist)
Ryouhei MORITA (Technical Scientist)

Contract Researchers
Hiroyuki ICHIDA
Kotaro ISHII

Yusuke KAZAMATechnical Staﬀ I
Yoriko HAYASHI

Yuki SHIRAKAWA

Technical Staﬀ II
Sumie OHBU
Taeko WAKANA

Mieko YAMADA

Research Consultants
Masahiro MII
Part-time Workers
Hideo TOKAIRIN

Sachiko KOGURE

Visiting Scientists
Makoto FUJIWARA (Univ. of Tokyo)
Masao WATANABE (Tohoku Univ.)
Hisashi TSUJIMOTO (Tottori Univ.)
Yutaka MIYAZAWA (Tohoku Univ.)
Toshinari GODO (Flower & Garden Bank)
Masanori TOMITA (CRIEPI)
Toshikazu MORISHITA (Nat’l. Inst. Agric. Res.)
Koji MURAI (Fukui Pref. Univ.)
Hinako TAKEHISA (Nat’l. Inst. Agric. Sci.)
Akiko HOKURA (Tokyo Denki Univ.)
Norihiro OHTSUBO (Kyoto Pref. Univ.)

Eitaro FUKATSU (Forestry and Forest Products Res. Inst.)
Tomonari HIRANO (Univ. of Miyazaki)
Yoichi SATO (Riken Food Co., Ltd.)Ali FERJANI (Tokyo Gakugei Univ.)
Katsutomo SASAKI (Nat’l Agric. and Food Res. Org.)
Kunio SUZUKI (Technoflora, Co., Ltd.)
Kazumitsu MIYOSHI (Chiba. Univ.)
Tadashi SATO (Tohoku Univ.)
Takeshi YAMAKI (Riken Vitamin Co., Ltd.)
Ayumi DEGUCHI (Chiba Univ.)
Kyosuke NIWA (Tokyo Univ. of Marine Sci. & Tech.)

Visiting Technicians
Takuji YOSHIDA (Takii Seed Co., Ltd.)
Daisuke SAITO (Riken Food Co., Ltd.)

Keiji IKEDA (KK SeaAct)
Yukiko KAWANISHI (Nippon Beet Sugar Mfg. Co., Ltd.)

Research Fellow
Hironari UCHIDA (Saitama Pref. Res. Inst.)
Student Trainees
Kazuki TAKANASHI (Tokyo Denki Univ.)
Yoshihiro TAKAHASHI (Kitazato Univ.)
Takuya NISHINOBO (Tokyo Denki Univ.)
Koichi NAMBU (Tokyo Denki Univ.)

Naoko HIROSE (Tokyo Denki Univ.)
Koya INOUE (Tokyo Denki Univ.)
Naoki OZEKI (Aichi Pref. Agric. Col.)- 342 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
S. Niwa, Y. Kazama, T. Abe, T. Ban, “Tracking haplotype for QTLs associated with Fusarium head blight resistance in Japanese wheat(Triticum aestivum L.) lineage,” Agriculture & Food Security 7, Article4 (2018). *A. Nishiura, S. Kitagawa, M. Matsumura, Y. Kazama, T. Abe, N. Mizuno, S. Nasuda, K. Murai, “An early-flowering einkorn wheat mutant
with deletions of PHYTOCLOCK 1/LUX ARRHYTHMO and VERNALIZATION 2 exhibits a high level of VERNALIZATION 1
expression induced by vernalization,” J. Plant Physiol. 222, 28–38 (2018). *H. Yamatani, K. Kohzuma, M. Nakano, T. Takami, Y. Kato, Y. Hayashi, Y. Monden, Y. Okumoto, T. Abe, T. Kumamaru, A. Tanaka,
W. Sakamoto, M. Kusaba, “Impairment of Lhca4, a subunit of LHCI, causes high accumulation of chlorophyll and the stay-green
phenotype in rice,” J. Exp. Bot. 69, 5, 1027–1035 (2018). *M. T. Fujiwara, M. Yasuzawa, K. H. Kojo, Y. Niwa, T. Abe, S. Yoshida, T. Nakano, R. D. Itoh, “The Arabidopsis arc5 and arc6 mutations
diﬀerentially aﬀect plastid morphology in pavement and guard cells in the leaf epidermis,” PLOS ONE 13, 2, e0192380 (2018). *Y. Koide, A. Ogino, T. Yoshikawa, Y. Kitashima, N. Saito, Y. Kanaoka, K. Onishi, Y. Yoshitake, T. Tsukiyama, H. Saito, M. Teraishi,Y. Yamagata, A. Uemura, H. Takagi, Y. Hayashi, T. Abe, Y. Fukuta, Y. Okumoto, A. Kanazawa, “Lineage-specific gene acquisition or loss
is involved in interspecific hybrid sterility in rice,” Proc. Natl. Acad. Sci. 115, 9, E1955-E1962 (2018). *Y. Kazama, T. Hirano, T. Abe, S. Matsunaga, “Chromosomal rearrangement: From induction by heavy-ion irradiation to in vivo engineering by genome editing,” Cytologia 83, 2, 125–128 (2018). *T. Takeshita, N. I. Ivanov, K. Oshima, K. Ishii, H. Kawamoto, S. Ota, T. Yamazaki, A. Hirata, Y. Kazama, T. Abe, M. Hattori, K. BiŠová,V. Zachleder, S. Kawano, “Comparison of lipid productivity of Parachlorella kessleri heavy-ion beam irradiation mutant PK4 in laboratory and 150-L mass bioreactor, identification and characterization of its genetic variation,” Algal Res. 35, 416–426 (2018). *L. Ma, Y. Kazama, T. Hirano, R. Morita, S. Tanaka, T. Abe, S. Hatakeyama, “LET dependence on killing eﬀect and mutagenicity in themodel filamentous fungus Neurospora crassa,” Int. J. Radiat. Biol. 94, 12, 1125–1133 (2018). *T. Yamazaki, E. Konosu, T. Takeshita, A. Hirata, S. Ota, Y. Kazama, T. Abe, S. Kawano, “Independent regulation of the lipid and starchsynthesis pathways by sulfate metabolites in the green microalga Parachlorella kessleri under sulfur starvation conditions,” Algal Res.
36, 37–47 (2018). *[Proceedings](Original Papers) *Subject to Peer Review
R. Sjahril, M. Riadi, Rafiuddin, T. Sato, K. Toriyama, T. Abe, R. A. Trisnawaty, “Eﬀect of heavy ion beam irradiation on germination of
local Toraja rice seed (M1-M2) mutant generation,” IOP Conf. Ser.: Earth Environ. Sci. 157, 012046 (2018[A10]).

Oral Presentations[International Conference etc.]
T. Abe, Y. Hayashi, R. Morita, H. Ichida, “Ion-beam mutagenesis —An innovative and eﬀective method for plant breeding and genediscovery,” FAO/IAEA International Symposium on Plant Mutation Breeding and Biotechnology, Vienna, Austria, Augest 2018.
M. Tomita, T. Tsukada, M. Izumi, “Bystander cell killing eﬀects induced by low-fluences of high-LET radiations,” the 64th Annual
Radiation Research Society Meeting, Chicago, USA, September 2018.
T. Abe, Y. Hayashi, R. Morita, H. Ichida, “An innovative method for plant mutation breeding and gene discovery,” 13th International
Conference on Nucleus-Nucleus Collisions, Saitama, Japan, December 2018.

[Domestic Conference]෩ؒ༟հ, ੴҪެଠ࿠, ฏ໺ஐ໵, एࡊົࢠ, ࢁాඒ‫ࢠܙ‬, େ෦੅ߐ, Ѩ෦஌ࢠ, ʮγϩΠψφζφมҟମͷશήϊϜϦγʔέϯεͰ໌Β͔ʹͨ͠ಥવมҟ༠ൃ΁ͷ LET ͷӨ‫ڹ‬ʯ, ೔ຊҭछֶձୈ 133 ճߨԋձ, ෱Ԭ, 2018 ೥ 3 ݄.
ࢢా༟೭, ৿ాཽฏ, ന઒ါ‫ر‬, ྛґࢠ, Ѩ෦஌ࢠ, ʮΠωແબൈΤΩιʔϜղੳʹΑΔॏΠΦϯϏʔϜ༠ൃมҟͷղੳʯ, ೔ຊҭछ
ֶձୈ 133 ճߨԋձ, ෱Ԭ, 2018 ೥ 3 ݄.
٢ా༞थ, ੒ాయ೭, ੕໺ཬಸ, ໼໺֮࢜, ෩ؒ༟հ, Ѩ෦஌ࢠ, ງ‫ޗޱ‬࿕, ௩୩༟Ұ, ʮϨʔβʔมҐηϯαଌఆʹΑΔγϩΠψφζ
φͷ༿ͷް͞มҟମͷ୯཭ͱղੳʯ, ୈ 59 ճ೔ຊ২෺ੜཧֶձ, ࡳຈ, 2018 ೥ 3 ݄.
R. Tabassum, T. Tanaka, T. Abe, “Analysis on White Immature Grains of the Rice Mutant Line 13-45 IV. Quantitative comparison amongcultivars,” ೔ຊ࡞෺ֶձୈ 245 ճߨԋձ, Ӊ౎‫ٶ‬, 2018 ೥ 3 ݄.
Ѩ෦஌ࢠ, ʮՃ଎‫ࢪث‬ઃͷಥવมҟҭछར༻—ॏΠΦϯϏʔϜҭछٕज़ͷ։ൃ—‫۝‬भγϯΫϩτϩϯޫ‫ڀݚ‬ηϯλʔ‫ڀݚ‬੒Ռใࠂձʢಛूɿ์ࣹޫΛத৺ͱͨ͠ྔࢠϏʔϜͷ೶‫ۀ‬ɾ‫ۀړ‬෼໺΁ͷߩ‫ݙ‬ʣ, ࠤլ, 2018 ೥ 8 ݄.
ాத๎೭, R. Tabassum, ಓࡔྯੜ, Ѩ෦஌ࢠ, ʮΠωಥવมҟ‫ܥ‬౷ 13-45 ʹ͓͚Δനະख़ཻൃੜ‫ߏػ‬ͷղੳ ୈ 5 ใɿ‫ݪ‬ҼީิҨ఻ࢠ࢈෺ͷ‫ػ‬ೳղੳʯ, ೔ຊ࡞෺ֶձୈ 246 ճߨԋձ, ࡳຈ, 2018 ೥ 9 ݄.
Ѩ෦஌ࢠ, ʮॏΠΦϯϏʔϜҭछͷ‫ݱ‬ঢ়ʯ, MIYADAI TAIYO AoiFarm Lab ΩοΫΦϑγϯϙδ΢Ϝ, ‫࡚ٶ‬, 2018 ೥ 10 ݄.

Posters Presentations[International Conference etc.]
Y. Oono, H. Ichida, R. Morita, S. Nozawa, T. Abe, H. Kato, Y. Hase, “Eﬀect of ion beams on rice genome sequence revealed by exome- 343 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)analysis,” 16th International Symposium on Rice Functional Genomics, Tokyo, Japan, September 2018.
Y. Kazama, K. Ishii, T. Hirano, M. Yamada, S. Ohbu, T. Abe, “Highly eﬃcient induction of chromosomal rearrangement by heavy-ion irradiation in the model plant Arabidopsis thaliana,” Principles of Chromosome Structure and Function, EMBL Symposium, Heidelberg,
Germany, September 2018.
T. Hirano, Y. Kazama, K. Ishii, N. Vuong, S. Ohbu, H. Kunitake, T. Abe, “Characterization of large flower mutants having chromosomal
rearrangements in the model plant Arabidopsis thaliana,” Principles of Chromosome Structure and Function, EMBL Symposium,
Heidelberg, Germany, September 2018.
H. Ichida, R. Morita, Y. Shirakawa, Y. Hayashi, T. Abe, “An exome sequencing based characterization of carbon ion beam-induced
mutations in an unselected rice population,” The 5th International Rice Congress, Singapore, Singapore, October 2018.

[Domestic Conference]ࠤ౻ཅҰ, ഡ‫྄ݪ‬, ࡈ౻େี, த༟೭, ദ୩৳Ұ, ฏ໺ஐ໵, ࢢా༟೭, ෱੢ெঘ, Ѩ෦஌ࢠ, Տ໺ॏߦ, খ໺ࠀಙ, ʮࡾ཮࢈ϫΧϝ༏ྑ‫ܥ‬౷։ൃͱ࣮༻Խʹ޲͚ͨऔΓ૊Έʯ, ೔ຊ૶ྨֶձୈ 42 ճେձ, ઋ୆, 2018 ೥ 3 ݄.
ԕ౻‫࢘و‬, ࠤ౻ߒࢠ, ੴ৿༟‫و‬, தࠐ༎հ, ࠤ౻խࢤ, ྛґࢠ, ࢢా༟೭, Ѩ෦஌ࢠ, ʮॏΠΦϯϏʔϜরࣹʹΑΔΠω༗༻มҟମͷ୳ࡧʯ, ೔ຊҭछֶձୈ 133 ճߨԋձ, ෱Ԭ, 2018 ೥ 3 ݄.
্ా७ฏ, ෩ؒ༟հ, Ѩ෦஌ࢠ, ଜҪߞೋ, ʮૣੜಥવมҟମίϜΪ‫ܥ‬౷ʹ͓͚ΔՖ੒஗Ԇ෮‫ؼ‬มҟମ late-heading 1 ͷಉఆʯ, ೔ຊҭछֶձୈ 133 ճߨԋձ, ෱Ԭ, 2018 ೥ 3 ݄.
৿ాཽฏ, ࢢా༟೭, Ұ੉উ‫ل‬, ന઒ါ‫ر‬, ྛґࢠ, ࠤ౻խࢤ, Ѩ෦஌ࢠ, ʮॏΠΦϯϏʔϜ༠ൃมҟͷ໢ཏత‫ݕ‬ग़ʹ޲͚ͨϓϩάϥϜͷ‫ݕ‬౼ʯ, ೔ຊҭछֶձୈ 133 ճߨԋձ, ෱Ԭ, 2018 ೥ 3 ݄.
த໺Ҁࡊ, ૬Ҫ৓ଠ࿠, খ৿ඒՂ, Ѩ෦஌ࢠ, ৿Լහ࿨, ླ໦ୡ࿠, ਗ਼ਫ໌ඒ, ాத༒࢘, ʮΠΦϯϏʔϜরࣹ༝དྷμολϯιό൒ᛙੑมҟମ sdb ʹ͓͚Δ‫ݪ‬ҼҨ఻ࢠͷಉఆʯ, ೔ຊҭछֶձୈ 133 ճߨԋձ, ෱Ԭ, 2018 ೥ 3 ݄.
ࢁ୩ߒ࢙, ্࠺֜ས, த໺ಓ࣏, ߴ‫ݟ‬ৗ໌, Ճ౻༟հ, ྛґࢠ, ໳ా༗‫ر‬, Ԟຊ༟, Ѩ෦஌ࢠ, ‫ؙ۽‬හത, ాதา, ࡔຊ࿱, ૲৔৴, ʮΠωstay-green ಥવมҟମ dye1 ͷ෼ࢠҨ఻ֶతղੳʯ, ୈ 59 ճ೔ຊ২෺ੜཧֶձ೥ձ, ࡳຈ, 2018 ೥ 3 ݄.
େ໺๛, ࢢా༟೭, ໺ᖒथ, ৿ాཽฏ, Ճ౻ߒ, Ѩ෦஌ࢠ, ௕୩७޺, ʮΠω୸ૉΠΦϯϏʔϜ༠ൃมҟମͷΤΩιʔϜղੳʯ, ୈ 59 ճ೔ຊ২෺ੜཧֶձ೥ձ, ࡳຈ, 2018 ೥ 3 ݄.
େ໺๛, ࢢా༟೭, ໺ᖒथ, ৿ాཽฏ, Ճ౻ߒ, Ѩ෦஌ࢠ, ௕୩७޺, ʮΠωʹ͓͚Δ୸ૉΠΦϯϏʔϜ༠ൃมҟͷΤΩιʔϜղੳʯ,ΠωҨ఻ֶɾ෼ࢠੜ෺ֶϫʔΫγϣοϓ 2018, ࡾౡ, 2018 ೥ 7 ݄.
Q. N. Vuong, ෩ؒ༟հ, ੴҪެଠ࿠, େ෦੅ߐ, ᅳ෢‫ొٱ‬, Ѩ෦஌ࢠ, ฏ໺ஐ໵, ʮγϩΠψφζφେྠมҟମϦιʔεΛ༻͍ͨՖ‫ث‬‫׭‬αΠζ੍‫ߏػޚ‬ͷղੳʯ, ೔ຊ২෺ֶձୈ 82 ճେձ, ޿ౡ, 2018 ೥ 9 ݄.
෩ؒ༟հ, ฏ໺ஐ໵, ੴҪެଠ࿠, एࡊົࢠ, ࢁాඒ‫ࢠܙ‬, େ෦੅ߐ, Ѩ෦஌ࢠ, ʮߴ LET ॏΠΦϯϏʔϜ͸ߴස౓Ͱછ৭ମ࠶ฤ੒Λ
༠ൃ͢Δʯ, ೔ຊ২෺ֶձୈ 82 ճେձ, ޿ౡ, 2018 ೥ 9 ݄.
෩ؒஐ඙, ࢢా༟೭, Ѩ෦஌ࢠ, ࠤ౻խࢤ, ௗࢁ‫࠸ێ‬, ʮࡉ๔࣭༤ੑෆູੑΠω΁ͷॏΠΦϯϏʔϜͱ EMS ॲཧʹΑΔູੑճ෮มҟମͷղੳʯ, ୈ 13 ճ ౦๺ҭछ‫ूڀݚ‬ձ, ߂લ, 2018 ೥ 11 ݄.
େ໺๛, ࢢా༟೭, ໺ᖒथ, ৿ాཽฏ, Ճ౻ߒ, Ѩ෦஌ࢠ, ௕୩७޺, ʮΠωʹ͓͚ΔΠΦϯϏʔϜ༠ൃมҟͷήϊϜղੳʯ, ୈ 41 ճ೔ຊ෼ࢠੜ෺ֶձ೥ձ, ԣ඿, 2018 ೥ 11 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Accelerator Applications Research Division
Beam Mutagenesis Group
Plant Genome Evolution Research Team
1. Abstract

The plant genome evolution research team studies the eﬀect of heavy-ion induced chromosomal rearrangements on plant phenotypes. Chromosome rearrangements including translocation, inversion, and deletion are thought to play an important role in evolution
and have a great potential to provide large phenotypic changes. However, this potential has not been fully investigated because of thelack 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 than that of theprevious techniques and allows characterization of the eﬀect of chromosomal rearrangements. By analyzing changes of gene expressions and chromatin statuses in mutants having chromosomal rearrangements, we study the eﬀect of the chromosome rearrangementson plant phenotypes of the mutants. In addition, we investigate the developmental process of a plant sex chromosome, which is a
representative example of the naturally occurring chromosomal rearrangements involved in adaptation and evolution.

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 formers
have both stamens and gynoecium, while the latter have no reproductive organs. By using the deletion status of these mutant lines, wepreviously developed S. latifolia Y chromosome map, which identified the location of both GSF and SPF on the same chromosome
arm. By whole-genome analysis and RNA seq analysis, we are now narrowing down the GSF and SPF regions.

Members
Team Leader
Yusuke KAZAMA
Research Part-time Workers
Sachiko USUDAHaruka WATANABE

Visiting Scientist
Tomonari HIRANO (Univ. of Miyazaki)
Student Trainee
Alvin SANMAYA (Sophia Univ.)- 345 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
N. Fujita, Y. Kazama, N. Yamagishi, K. Watanabe, S. Ando, H. Tsuji, S. Kawano, N. Yoshikawa, K. Komatsu, “Development of the VIGS
system in the dioecious plant Silene latifolia,” Int. J. Mol. Sci. 20, E1031 (2019).
(2019).*
Y. Kazama, T. Hirano, T. Abe, S. Matsunaga, “Chromosomal rearrangement: from induction by heavy-ion irradiation to in vivo engineering by genome editing,” Cytologia 83, 125–128 (2018).*(2018).
L. Ma, Y. Kazama, T. Hirano, R. Morita, S. Tanaka, T. Abe, S. Hatakeyama, “LET dependence on killing eﬀect and mutagenicity in themodel filamentous fungus Neurospora crassa,” Int. J. Radiation. Biol. 94,1125–1133 (2018).
(2018).*
T. Yamazaki, E. Konosu, T. Takashita, A. Hirata, S. Ota, Y. Kazama, T. Abe, S. Kawano, “Independent regulation of the lipid and starchsynthesis pathways by sulfate metabolites in the green microalga Parachlorella kessleri under sulfur starvation-conditions,” Algal Res.
36, 37–47 (2018).
(2018).*
T. Takeshita, I. N. Ivanov, K. Oshima, K. Ishii, H. Kawamoto, S. Ota, T. Yamazaki, A. Hirata, Y. Kazama, T. Abe, M. Hattori, K. Bisova,
V. Zachleder, S. Kawano, “Comparison of lipid productivity of Parachlorella kessleri heavy-ion beam irradiation mutant PK4 in(2018).*
laboratory and 150-L mass bioreactor, identification and characterization of its genetic variation,” Algal Res. 35, 416–426 (2018).

Oral Presentations[Domestic Conference]෩ؒ༟հ, ʮ೉͍͚͠Ͳ໘ന͍ʂ২෺‫ڊ‬େ Y છ৭ମͷ‫ڀݚ‬ʯ, ୈ̐ճ೶ֶதखͷձ, େ௡, 2018 ೥ 12 ݄.
Y. Kazama, “Study of plant sex chromosome by using heavy-ion induced mutants. 1st Symposium on heavy and cluster ions mutagenesisof microorganisms for finding solutions to the issue of hyper-productivity, energy and environment,” Tsukuba, January 29, 2019.

Posters Presentations[International Conference etc.]
K. Ishii, Y. Kazama, T. Hirano, T. Takeshita, S. Kawano, T. Abe, “Development of a pipeline for whole-genome mutational analysis and
Its application on heavy-ion mutagenesis,” Plant and Animal Genome XXVII Conference, San Diego, January 2019.
T. Hirano, Y. Kazama, K. Ishii, V. Q. Nhat, S. Ohbu, H. Kunitake, T. Abe, “Characterization of large flower mutants having chromosomal rearrangements in the model plant Arabidopsis thaliana,” EMBO|EMBL Symposium: Principles of Chromosome Structure andFunction, Heidelberg, Germany, September 2018.
Y. Kazama, K. Ishii, T. Hirano, M. Yamada, S. Ohbu, T. Abe, “Highly eﬃcient induction of chromosomal rearrangement by heavy-ion
irradiation in the model plant Arabidopsis thaliana,” EMBO|EMBL Symposium: Principles of Chromosome Structure and Function,
Heidelberg, Germany, September 2018.

[Domestic Conference]
Q. N. Vuong, ෩ؒ༟հ, ੴҪެଠ࿠, େ෦੅ߐ, ᅳ෢‫ొٱ‬, Ѩ෦஌ࢠ, ฏ໺ஐ໵, ʮγϩΠψφζφେྠมҟମϦιʔεʹ͓͚ΔՖ‫ث‬‫׭‬αΠζ੍‫ߏػޚ‬ͷղੳʯ, ೔ຊ২෺ֶձୈ 82 ճେձ, ޿ౡ, 2018 ೥ 9 ݄.
෩ؒ༟հ, ฏ໺ஐ໵, ੴҪެଠ࿠, एࡊົࢠ, ࢁాඒ‫ࢠܙ‬, େ෦੅ߐ, Ѩ෦஌ࢠ, ʮߴ LET ॏΠΦϯϏʔϜ͸ߴස౓Ͱછ৭ମ࠶ฤ੒Λ
༠ൃ͢Δʯ, ೔ຊ২෺ֶձୈ 82 ճେձ, ޿ౡ, 2018 ೥ 9 ݄.
౻ాঘࢠ, ෩ؒ༟հ, ࢁ‫ࢠل؛‬, ҆౻࡙, ௰‫׮‬೭, ٢઒৴޾, খদ݈, ʮ΢ΠϧεϕΫλʔΛར༻ͨ͠ώϩϋϊϚϯςϚͷҨ఻ࢠ‫ػ‬ೳղੳ‫ܥ‬ͷཱ֬ʯ, ೔ຊ২෺ֶձୈ 82 ճେձ, ޿ౡ, 2018 ೥ 9 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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
Group Director
Hiromitsu HABATeam Leader
Atsushi YOSHIDA

List of Publications & Presentations
See the subsections of Nuclear Chemistry Research Team and Industrial Application Research Team.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Accelerator Applications Research Division
RI Application Research Group
Nuclear Chemistry Research Team
1. Abstract

The Nuclear Chemistry Research Team develops production technologies of radioisotopes (RIs) at RIKEN RI Beam Factory(RIBF) for application studies in the fields of physics, chemistry, biology, engineering, medicine, pharmaceutical and environmental
sciences. We use the RIs mainly for nuclear and radiochemical studies such as RI production and superheavy element chemistry.
The purified RIs such as 65 Zn, 67 Cu, 85 Sr, 88 Y, and 109 Cd are delivered to universities and institutes through Japan Radioisotope
Association. We also develop new technologies of mass spectrometry for the trace-element analyses using accelerator technology andapply 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, IRMS, and so on. We also develop chemical materials 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 14-MeV proton, 24-MeV deuteron, and 50-MeV alpha beams from the AVF cyclotron, we presently
produce about 50 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, and 197 Au irradiated witha 135-MeV/nucleon 14 N beam from the RIKEN Ring Cyclotron. These multitracers are also supplied to universities and institutes as
collaborative researches.
In 2018, we developed production technologies of radioisotopes such as 24 Na, 42, 43 K, 44m Sc, 74 As, 124 Sb, 111 Ag, 206 Bi, and 211 At
which were strongly demanded but lack supply sources in Japan. We also investigated the excitation functions for the nat Zn(d, x),89
Y(d, x), 93 Nb(d, x), nat Pd(d, x), 159 Tb(d, x), nat Er(d, x), nat Ni(α, x), 169 Tm(α, x), and nat W(α, x) reactions to quantitatively produce
useful RIs. We used radiotracers of 206 Bi and 211 At for application studies in chemistry, 24 Na, 42, 43 K, 44m Sc, 67 Cu, and 211 At in nuclear
medicine. We also produced 65 Zn and 88 Y for our scientific researches on a regular schedule and supplied the surpluses through Japan
Radioisotope Association to the general public. In 2018, we accepted 3 orders of 65 Zn with a total activity of 9.7 MBq and 2 orders of88
Y with 2 MBq. We also distributed 44m Sc (10 MBq × 1), 88 Zr (1 MBq × 1 and 2 MBq × 3), 95 Nb (2 MBq × 3), 121m Te (2 MBq × 2),
124
Sb (2 MBq × 1), 175 Hf (1 MBq × 1 and 2 MBq × 1), 179 Ta (1 MBq × 2), and 211 At (5 MBq × 3, 10 MBq × 2, 40 MBq × 1, 50 MBq ×
1, 70 MBq × 1, 80 MBq × 5, and 100 MBq × 4) 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 line of AVF.
In 2018, 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). The co-precipitation behaviorof 255 No with Sm hydroxide was also investigated with the computer-controlled suction filtration apparatus for the preparation of
precipitated samples of heavy elements (CHIN). In 2018, we also produced radiotracers of 88 Zr, 95 Nb, 95m Tc, 175 Hf, 177, 179 Ta, and- 348 -

Ⅵ. RNC ACTIVITIES183

RIKEN Accel. Prog. Rep. 52 (2019)

Re at AVF and conducted model experiments for aqueous chemistry studies on Rf, Db, and Bh.

(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 2018, 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 theestablishment of the Yamato dynasty in the period from Jomon to Tumulus. In 2018, we improved the sensitivity in the S isotopic
analyses using “trapping and focusing” techniques and analyzed pigments of the Roman ruins. We improved the sampling method forthe pigments using a S-free adhesive tape. We applied this method to analyze the red-color substances on the artifacts from Kyoden
remains from Izumo to show that they were originated from Hokkaido. We also measured Pd isotopic ratios to investigate the 107 Pd
transmutation.
(4) Development of chemical materials for ECR ion sources of the heavy-ion accelerators at RIBF
In 2018, 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
Postdoctoral Researchers
Kaustab GHOSH
Yang WANG

Yukiko KOMORI
Takuya YOKOKITA

Technical Staﬀ I
Daiki MORI
Research Consultants
Hisaaki KUDO
Part-time Workers
Michiko KITAGAWA
Nozomi SATO

Minako OSANAI

Visiting Scientists
Masayuki AIKAWA (Hokkaido Univ.)
Aya SAKAGUCHI (Univ. of Tsukuba)
Kazuhiko AKIYAMA (Tokyo Met. Univ.)
Miho SATAKE (Fujifilm Toyama Chem. Co., Ltd.)
Osuke FUJIMOTO (Fujifilm Toyama Chem. Co., Ltd.)
Kenji SHIMAZOE (Univ. of Tokyo)
Hayato IKEDA (Tohoku Univ.)
Keisuke SUEKI (Univ. of Tsukuba)
Noriko ISHIOKA (Takasaki Advanced Rad. Res. Inst., QST)
Kentaro SUZUKI (Fujifilm Toyama Chem. Co., Ltd.)
Masamichi KAJITA (Fujifilm Toyama Chem. Co., Ltd.)
Hiroyuki TAKAHASHI (Univ. of Tokyo)
Hiroshi KATO (Fujifilm Toyama Chem. Co., Ltd.)
Miho TAKAHASHI (Tokyo Univ. Marine Sci. and Tech.)
Hirokazu KAWAMURA (Tohoku Univ.)
Miwako TAKAHASHI (National Inst. of Radiological Sci.,
QST)
Mayeen Uddin KHANDAKER (Sunway Univ.)
Yuichi TAKAKU (Institute for Environmental Sci.)
Hidetoshi KIKUNAGA (Tohoku Univ.)
Hiroki TAKASHIMA (National Cancer Center Japan)

Yoshikatsu KOGA (National Cancer Center Japan)
Kazuo TANAKA (Tohoku Univ.)
Shoko KUBOTA (Fujifilm Toyama Chem. Co., Ltd.)
Masayoshi TODA (Tokyo Univ. Marine Sci. and Tech.)
Takumi KUBOTA (Kyoto Univ.)
Atsushi TOYOSHIMA (Osaka Univ.)
Susanta Kumar LAHIRI (Saha Institute of Nucl. Phys.)
Takashi UI (Fujifilm Toyama Chem. Co., Ltd.)
Toshimitsu MOMOSE (International Univ. Health Welfare)
Naoyuki UKON (Fukushima Med. Univ.)
Akio NAGANO (Fujifilm Toyama Chem. Co., Ltd.)
Akihiko YOKOYAMA (Kanazawa Univ.)
Eri NAKAMURA (Fujifilm Toyama Chem. Co., Ltd.)
Zenko YOSHIDA (ATOX Co., Ltd.)
Kazuhiro OOE (Osaka Univ.)
Koji YOSHIMURA (Okayama Univ.)
Shinobu OSHIKIRI (Fujifilm Toyama Chem. Co., Ltd.)
Shigeki WATANABE (Takasaki Advanced Rad. Res. Inst.,
QST)
Yasutaka SAITO (Fujifilm Toyama Chem. Co., Ltd.)- 349 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Visiting Technicians
Akimitsu KANDA (Japan Radioisotope Association)
Yuichirou WAKITANI (Japan Radioisotope Association)
Yuki TAKEMURA (ATOX Co., Ltd.)

Mami YUKI (ATOX Co., Ltd.)
Shusaku TAZAWA (ATOX Co., Ltd.)

Student Trainees
Sadia ADACHI (Univ. of Tsukuba)
Masahiro NAGASE (Osaka Univ.)
Wei Seng FOONG (Univ. of Tokyo)
Yuki NARUSE (Niigata Univ.)
Yuta HAYAKAWA (Kanazawa Univ.)
Hidemi NINOMIYA (Osaka Univ.)
Sho HAYAMI (Osaka Univ.)
Sho OKUBO (Okayama Univ.)
Xuan HOU (Univ. of Tokyo)
Ryota OZAKI (Okayama Univ.)
Takumi IKEDA (Osaka Univ.)
Moemi SAITOH (Hokkaido Univ.)
Junpei INAGAKI (Univ. of Tsukuba)
Michiya SAKAGUCHI (Hokkaido Univ.)
Saki ITO (Tohoku Univ.)
Daisuke SATO (Niigata Univ.)
Ayuna KASHIHARA (Univ. of Tsukuba)
Keita SEKIGUCHI (Univ. of Tsukuba)

Cheonghun KIM (Univ. of Tokyo)
Yudai SHIGEKAWA (Osaka Univ.)
Michiko KITAGAWA (Kindai Univ.)
Kaori SHIRAI (Niigata Univ.)
Mariko KOBAYASHI (Univ. of Tokyo)
Kenta SUZUKI (Okayama Univ.)
Narumi KONDO (Osaka Univ.)
Tomohiro TOMITSUKA (Niigata Univ.)
Masaharu KURINO (Univ. of Tokyo)
Eisuke WATANABE (Osaka Univ.)
Ryoga MORITA (Kanazawa Univ.)
Kouhei YAMAMORI (Kanazawa Univ.)
Takuya MORIYAMA (Niigata Univ.)
Yuki YASUDA (Osaka Univ.)
Mayu MURATA (Kanazawa Univ.)
Zhihong ZHONG (Univ. of Tokyo)
Tomohiro MURATA (Hokkaido Univ.)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
M. Rosenbusch, Y. Ito, P. Schury, M. Wada, D. Kaji, K. Morimoto, H. Haba, S. Kimura, H. Koura, M. MacCormick, H. Miyatake,J. Y. Moon, K. Morita, I. Murray, T. Niwase, A. Ozawa, M. Reponen, A. Takamine, T. Tanaka, H. Wollnik, “New mass anchor points
for neutron-deficient heavy nuclei from direct mass measurements of radium and actinium isotopes,” Phys. Rev. C 97, 064306 1–8(2018). *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. X. Watanabe, H. Wollnik, S. Yamaki, “First direct mass measurements of nuclides around Z = 100 with a multireflection time-offlight mass spectrograph,” Phys. Rev. Lett. 120, 152501 1–6 (2018). *N. Ukon, M. Aikawa, Y. Komori, H. Haba, “Production cross sections of deuteron-induced reactions on natural palladium for Ag isotopes,”
Nucl. Instrum. Methods Phys. Res. B 426, 13–17 (2018). *M. Aikawa, M. Saito, N. Ukon, Y. Komori, H. Haba, “Activation cross sections of alpha-induced reactions on nat In for 117m Sn production,”
Nucl. Instrum. Methods Phys. Res. B426, 18–21 (2018). *M. Aikawa, M. Saito, S. Ebata, Y. Komori, H. Haba, “Activation cross sections of α-induced reactions on nat Zn for Ge and Ga production,”
Nucl. Instrum. Methods Phys. Res. B 427, 91–94 (2018). *S. Kimura, Y. Ito, D. Kaji, P. Schury, M. Wada, H. Haba, T. Hashimoto, Y. Hirayama, M. MacCormicke, H. Miyatake, J. Y. Moon,
K. Morimoto, M. Mukai, I. Murray, A. Ozawa, M. Rosenbusch, H. Schatz, A. Takamine, T. Tanaka, Y. X. Watanabe, H. Wollnik,“Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-offlight mass spectrograph,” Int. J. Mass Spectrom. 430, 134–142 (2018). *K. Morita, K. Morimoto, D. Kaji, H. Haba, H. Kudo, “Discovery of new element, nihonium, and perspectives,” Prog. Nucl. Sci. Technol.
5, 8–13 (2018). *F. Ditrói, S. Takács, H. Haba, Y. Komori, M. Aikawa, M. Saito, T. Murata, “Investigation of alpha particle induced reactions on naturalsilver in the 40–50 MeV energy range,” Nucl. Instrum. Methods Phys. Res. B 436, 119–129 (2018). *L. Lens, A. Yakushev, C. E. Düllmann, M. Asai, J. Ballof, M. Block, H. M. David, J. Despotopulos, A. D. Nitto, K. Eberhardt, J. Even,
M. Götz, S. Götz, H. Haba, L. Harkness-Brennan, F. P. Heßberger, R. D. Herzberg, 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, J. Runke, M. Schädel, P. Scharrer, T. Sato,
D. Shaughnessy, B. Schausten, P. Thörle-Pospiech, N. Trautmann, K. Tsukada, J. Uusitalo, A. Ward, M. Wegrzecki, N. Wiehl, V. Yakusheva, “Online chemical adsorption studies of Hg, Tl, and Pb on SiO2 and Au surfaces in preparation for chemical investigations on
Cn, Nh, and Fl at TASCA,” Radiochim. Acta 106, 949–962 (2018). *E. Tsantini, T. Minami, K. Takahashi, M. Á. C. Ontiveros, “Analysis of sulphur isotopes to identify the origin of cinnabar in the Roman
wall paintings from Badalona (Spain),” J. Arcaeological. Sci. Rep. 18, 300–307 (2018). *- 350 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

K. Takahashi, Y. Nakai, Y. Motizuki, T. Ino, S. Ito, S. B. Ohkubo, T. Minami, Y. Takaku, Y. Yamaguchi, M. Tanaka, H. Motoyama, “Highsensitivity sulfur isotopic measurements for Antarctic ice core analyses,” Rapid Commun. Mass Spectrom. 32, 1991–1998 (2018). *T. Murata, M. Aikawa, M. Saitoc, N. Ukon, Y. Komori, H, Haba, S. Takács, “Production cross sections of Mo, Nb and Zr radioisotopes
from α-induced reaction on nat Zr,” Appl. Radiat. Isot. 144, 47–53 (2019). *H. Haba, “A new period in superheavy-element hunting,” Nat. Chem. 11, 10–13 (2019). *A. Yokoyama, Y. Kitayama, Y. Fukuda, H. Kikunaga, M. Murakami, Y. Komori, S. Yano, H. Haba, K. Tsukada, A. Toyoshima, “Extraction
behavior of rutherfordium as a cationic fluoride complex with a TTA chelate extractant from HF/HNO3 acidic solutions,” Radiochim.
Acta 107, 27–32 (2019). *K. Fujiki, Y. Kanayama, S. Yano, N. Sato, T. Yokokita, P. Ahmadi, Y. Watanabe, H. Haba, K. Tanaka, “211 At-labeled immunoconjugate via
a one-pot three-component double click strategy: practical access to a-emission cancer radiotherapeutics,” Chem. Sci. 10, 1936–1944(2019). *Y. Wang, S. Cao, J. Zhang, F. Fan, J. Yang, H. Haba, Y. Komori, T. Yokokita, K. Morimoto, D. Kaji, Y. J. Wittwer, R. Eichler, A. Türler,
Z. Qin, “The study of rhenium pentacarbonyl complexes using single-atom chemistry in gas phase,” Phys. Chem. Chem. Phys. 21,
7147–7154 (2019). *F. Miyake, K. Horiuchi, Y. Motizuki, Y. Nakai, K. Takahashi, K. Masuda, H. Motoyama, H. Matsuzaki, “10 Be signature of the cosmic
ray event in the 10th century CE in both hemispheres, as confirmed by quasi-annual 10 Be data from the Antarctic Dome Fuji ice core,”
Geophys. Res. Lett. 46, 11–18 (2019). *Ӌ৔޺ޫ, ʮGARIS ͕୓͘௒ॏ‫ݩ‬ૉͷԽֶ—106 ൪‫ݩ‬ૉγʔϘʔΪ΢ϜͷΧϧϘχϧࡨମͷ߹੒—ʯ, Radioisotopes 67, 527–535(2018). *Ӌ৔޺ޫ, ʮ௒ॏ‫ݩ‬ૉͷ߹੒—‫ࢠݪ‬൪߸ 113 Ҏ߱ͷ௒ॏ‫ݩ‬ૉͷ߹੒ͱൃ‫—ݟ‬ʯ, Radioisotopes 67, 277–289 (2018). *Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 1. ‫ݩ‬ૉͷൃ‫ͱݟ‬प‫ظ‬දʯ, ‫ݱ‬୅Խֶ 4, No. 565, 34–37 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 2. ಉҐମͱ֩ਤදʯ, ‫ݱ‬୅Խֶ 5, No. 566, 18–21 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 3. ਓ޻‫ݩ‬ૉʯ, ‫ݱ‬୅Խֶ 6, No. 567, 44–48 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 4. ‫ݬ‬ͷ৽‫ݩ‬ૉʯ, ‫ݱ‬୅Խֶ 7, No. 568, 36–39 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 5. ௒ॏ‫ݩ‬ૉʯ, ‫ݱ‬୅Խֶ 8, No. 569, 40–43 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 6. ཧ‫ݚ‬ͷ৽‫ݩ‬ૉ୳ࡧ (1)ʯ, ‫ݱ‬୅Խֶ 9, No. 570, 24–28 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 7. ཧ‫ݚ‬ͷ৽‫ݩ‬ૉ୳ࡧ (2)ʯ, ‫ݱ‬୅Խֶ 10, No. 571, 53–57 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 8. ཧ‫ݚ‬ͷ৽‫ݩ‬ૉ୳ࡧ (3)ʯ, ‫ݱ‬୅Խֶ 11, No. 572, 25–28 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 9. ϩγΞͱถࠃʹΑΔ৽‫ݩ‬ૉ୳ࡧʯ, ‫ݱ‬୅Խֶ 12, No. 573, 52–56 (2018).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 10. χϗχ΢Ϝ໋໊ʯ, ‫ݱ‬୅Խֶ 1, No. 574, 44–49 (2019).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 11. ͞ΒͳΔ৽‫ݩ‬ૉΛ‫ٻ‬Ίͯʯ, ‫ݱ‬୅Խֶ 2, No. 575, 42–46 (2019).
Ӌ৔޺ޫ, ʮχϗχ΢Ϝ͸͍͔ʹͯ͠஀ੜͨ͠ͷ͔ 12. ৽‫ݩ‬ૉͷԽֶతੑ࣭ʯ, ‫ݱ‬୅Խֶ 3, No. 576, 42–46 (2019).
ླ໦ஐ࿨, ౉෦ߒ࢘, ٠Ӭӳण, Ӌ৔޺ޫ, ෱ాޫ޺, ʮ୹ण໋ RI ‫څڙ‬ϓϥοτϑΥʔϜ࣮‫ݱ‬ͷͨΊͷ์ࣹઢো֐๷ࢭ๏্ͷखଓ͖ʹ͍ͭͯʯ, ೔ຊ์ࣹઢ҆શ؅ཧֶձࢽ ୈ 17 ‫ר‬, 2 ߸, 121–124 (2018). *Տ໺ຎ໹, ߴ‫ڮ‬࿨໵, ࠓ௡અੜ, ೆ෢ࢤ, ʮ෱Ԭ‫҆ݝ‬ಙ୆Ҩ੻‫͚͓ʹ܈‬Δगͷ࢖͍෼͚ʹ͍ͭͯʯ, ‫ݹ‬୅, ୈ 142 ߸, 97–103 (2018). *[Proceedings]
T. Karino, M. Okamura, H. Haba, T. Kanesue, S. Ikeda, S. Kawata, “Characteristic investigation of 96 Zr oxide,” AIP Conf. Proc. 2011,070004 1–3 (2018). *[Book]ࡩҪ߂, ࠜ໼ࡾ࿠, ࣉౢ޹ਔ, ࡫৿‫و‬༟, Ӌ৔޺ޫ, ʮ‫ݩ‬ૉ‫ݕ‬ఆ 2ʯ
, Խֶಉਓ, 2018 ೥ 8 ݄ 20 ೔.
ߴ‫ڮ‬࿨໵, ೆ෢ࢤ, ʮ2018 ೥౓‫ాژ‬Ҩ੻ൃ۷ௐࠪใࠂॻ, ୈ 5 અ 4 ۠ग़౔Ҩ෺෇ணҟ෺ਫۜगͷེԫಉҐମൺ෼ੳʯ, ग़ӢࢢจԽࡒ
՝, 2019 ೥ 3 ݄.

Oral Presentations[International Conference etc.]
T. Murata, M. Aikawa, M. Saito, N. Ukon, Y. Komori, H. Haba, S. Takács, “99 Mo production from α-induced reaction on 96 Zr,” The 18th
Radiochemical Conference (RadChem 2018), Mariánské Lázne, Czech Republic, May 2018.
M. Saito, M. Aikawa, T. Murata, N. Ukon, Y. Komori, H. Haba, S. Takacs, “Production cross section measurement of alpha induced
reaction on nat Yb to produce medical RI 177 Lu,” The 18th Radiochemical Conference (RadChem 2018), Mariánské Lázne, Czech
Republic, May 2018.
A. Yokoyama, A. Sakaguchi, K. Yamamori, Y. Hayakawa, K. Sekiguchi, S. Yanou, Y. Komori, T. Yokokita, H. Haba, N. Takahashi,
A. Shinohara, “Production of Np isotopes in nuclear reactions for a standard material in accelerator mass spectrometry,” The 18th
Radiochemical Conference (RadChem 2018), Mariánské Lázne, Czech Republic, May 2018.
H. Haba, “Production and applications of radioisotopes at RIKEN RI Beam Factory,” Seminar at Brookhaven National Laboratory, New
York, USA, May 2018.
H. Haba, “Synthesis and chemistry of superheavy elements at RIKEN,” DAE-BRNS Eighth Biennial Symposium on Emerging Trends in
Separation Science and Technology (SESTEC-2018), Goa, India, May 2018.
H. Haba, “Production and applications of radioisotopes at RIKEN RI Beam Factory,” Seminar at Inter-University Accelerator Centre,- 351 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

New Delhi, India, May 2018.
H. Haba, “Applications with unstable ion beams and complementary techniques at the RIKEN,” Consultancy Meeting on Novel Multidisciplinary Applications with Unstable Ion Beams and Complementary Techniques, Vienna, Austria, July 2018.
K. Takahashi, H. Motoyama, “The isotopic measurements of oxygen and hydrogen in Dome-Fuji (Antarctica) ice core: Annually-resolved
temperature reconstructions of the past 2000 years,” The 4th International Conference on Water Resource and Environment (WRE2018), Kaoshiung, Taiwan, July 2018.
H. Haba, “Present status and perspectives of SHE researches at RIKEN,” IX International Symposium on Exotic Nuclei (EXON-2018),
Petrozavodsk, Russia, September 2018.
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. X. Watanabe, H. Wollnik, S. Yamaki, “Direct mass measurements of heavy/superheavy nuclei with an MRTOF-MS coupled with the
GARIS-II,” The International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) 2018, Geneva, Switzerland, September 2018.
M. Rosenbusch, Y. Ito, M. Wada, P. Schury, 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, A. Takamine, T. Tanaka,
Y. X. Watanabe, H. Wollnik, S. Yamaki, “Advances and future plans for nuclear mass measurements at RIKEN,” The International
Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) 2018, Geneva, Switzerland, September 2018.
M. Mukai, Y. Hirayama, Y. X. Watanabe, P. Schury, 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, H. Miyatake, “Development of a multi-segmented proportional gas counter for
β-decay spectroscopy at KISS,” The International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS) 2018,
Geneva, Switzerland, September 2018.
H. Haba, “Production of radioisotopes for application studies at RIKEN RI Beam Factory,” 4th International Conference on Applicationof RadiotraCers and Energetic Beams in Sciences (ARCEBS-2018), Kolkata, India, November 2018.
Y. Komori, H. Haba, T. Yokokita, S. Yano, N. Sato, K. Ghosh, Y. Sakemi, H. Kawamura, “Measurement of excitation functions of the
206/207/208
Pb(11 B, x)212 Fr reactions and complex formation studies of Fr with crown ethers,” 4th International Conference on Applicationof RadiotraCers and Energetic Beams in Sciences (ARCEBS-2018), Kolkata, India, November 2018.
H. Haba, “Production and application of radioisotopes using He jet transport system at RIKEN RI Beam Factory,” Seminar at Variable
Energy Cyclotron Centre, Kolkata, India, November, 2018.
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, K. Hagino, “Fusion dynamics for
hot fusion reactions revealed in quasielastic fusion barrier distributions,” 13th International Conference on Nucleus-Nucleus Collisions,Omiya, Japan, December 2018.
H. Haba, “Production of radioisotopes for gamma-ray imaging at RIKEN RI Beam Factory,” Workshop on Multiple Photon Coincidence
Imaging, Narita, Japan, December 2018.
H. Haba, “Production of radioisotopes for application studies at RIKEN RI Beam Factory,” Technical Meeting on Novel Multidisciplinary
Applications with Unstable Ion Beams and Complementary Techniques, Vienna, Austria, December 2018.
Y. Komori, “Activities related to SHE target production and aqueous chemistry of SHEs at RIKEN,” NUSPRASEN Workshop on Superheavy element research, target techniques and related topics, GSI, Darmstadt, Germany, February 2019.
H. Haba, “Present status and perspectives of SHE researches at RIKEN,” NUSPRASEN Workshop on Superheavy element research,target techniques and related topics and NUSTAR Annual Meeting 2019, Darmstadt, Germany, February 2019.

[Domestic Conference]
H. Haba, “Present status and perspectives of superheavy element chemistry at RIKEN,” ‫ڀݚ‬ձʮ௒ॏ‫ݩ‬ૉ‫ڀݚ‬ͷ৽ల։ʯ, ෱Ԭ, 2018
೥ 7 ݄.
ೆ෢ࢤ, ߴ‫ڮ‬࿨໵, ʮ௒ඍྔེԫಉҐମ෼ੳ๏ͷ։ൃͱߟ‫ࢼֶݹ‬ྉ෼ੳͷར఺ʯ, ೔ຊจԽࡒՊֶձୈ 35 ճେձ, ಸྑ, 2018 ೥ 7 ݄.
Ӌ৔޺ޫ, ʮཧ‫͚͓ʹݚ‬Δ RI ੡଄Ԡ༻ʙ৽‫ݩ‬ૉͷԽֶ͔Β֩ҩֶͷ਍அɾ࣏ྍ·Ͱʙʯ, େࡕେֶ์ࣹઢՊ‫ج‬൫‫ൃߏػ‬଍‫ه‬೦γϯϙδ΢Ϝ, ๛த, 2018 ೥ 8 ݄.
খ৿༗‫ࢠر‬, ʮཧ‫͚͓ʹݚ‬Δ௒ॏ‫ݩ‬ૉԽֶ‫ڀݚ‬ͷ‫ݱ‬ঢ়ͱকདྷ‫ܭ‬ըʯ, ୈ 57 ճ֩ԽֶՆͷֶߍ, ௕໺, 2018 ೥ 8 ݄.
ఉ੉‫ོڿ‬, ࿨ాಓ࣏, P. Schury, ҏ౻༝ଠ, Ճ࣏େ࠸, M. Rosenbusch, ໦ଜ૑େ, ৿ຊ޾࢘, Ӌ৔޺ޫ, ੴᖒྙ, ৿ాߒհ, ‫ٶ‬෢Ӊ໵,
H. Wollnik, ʮMRTOF-MS ༻ͷ α-ToF ‫ݕ‬ग़‫ث‬ͷੑೳධՁʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫౎ژ‬, 2018 ೥ 9݄.
ւ࿝‫ॆݪ‬, େӜହ࢚, നҪ௚थ, Ӭ઒ӫହ, ᓎҪঢ, Ӌ৔޺ޫ, দ࡚ߒ೭, ௽ా࣏༤, ৿‫ޱ‬༞Ұ, ʮट౎‫ʹݍ‬ඈདྷͨ͠෱ౡ‫ނࣄൃݪ‬༝དྷͷ์ࣹੑΤΞϩκϧதͷ 129 I/131 I ൺʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫౎ژ‬, 2018 ೥ 9 ݄.
ࠤ౻๬, Ӌ৔޺ޫ, ԣ๺୎໵, Ghosh Kaustab, Wang Yang, খ৿༗‫ࢠر‬, ৿େً, ߴ‫ڮ‬࿨໵, ໦ଜढ़෉, দຊ‫װ‬༤, ʮཧ‫͚͓ʹݚ‬Δ At-211
ͷ੡଄൦෍ʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫౎ژ‬, 2018 ೥ 9 ݄.
খ৿༗‫ࢠر‬, ʮnat Mo(d, x) ͓Αͼ nat W(d, x) ൓ԠʹΑΔ Tc, Re ಉҐମͷੜ੒அ໘ੵଌఆʯ
, Chemical Probe ߹॓‫ࣜܗ‬ηϛφʔ, ઍ༿,2018 ೥ 10 ݄.
Ӌ৔޺ޫ, ʮ৽‫ݩ‬ૉχϗχ΢Ϝൃ‫΁ݟ‬ͷಓͷΓʯ, ୈ 5 ճ‫ح‬ੴത෺‫ؗ‬αΠΤϯεΧϑΣ, ෋࢜‫ٶ‬, 2018 ೥ 10 ݄.
ࣰ‫ްݪ‬, ๛ౢް࢙, ٢ଜਸ, ݉ా (தౡ) Ճचࢠ, ுࢠ‫ݟ‬, Ӭాޫ஌࿠, ౉෦௚࢙, ാᖒॱ, େߐҰ߂, ࢁଜே༤, ന࡚‫࣍ݠ‬, ٠Ӭӳण, Ӌ৔޺ޫ, ࿯ࢁ޾৴, ʮ୹ण໋ α ઢ֩छͷඈࢄ཰౳ͷ‫ૅج‬σʔλऔಘͱ߹ཧత๏‫͚҆ͨ޲ʹ੍ن‬શੑ‫ࣹ์ͱূݕ‬ઢ؅ཧ๏ͷ։ൃʯ,೔ຊ์ࣹઢ҆શ؅ཧֶձୈ 17 ճֶज़େձ, ໊‫ݹ‬԰, 2018 ೥ 12 ݄.

- 352 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)๛ౢް࢙, ࣰ‫ްݪ‬, ٢ଜਸ, ݉ా (தౡ) Ճचࢠ, ுࢠ‫ݟ‬, Ӭాޫ஌࿠, ౉෦௚࢙, େߐҰ߂, ࢁଜே༤, ന࡚‫࣍ݠ‬, ٠Ӭӳण, Ӌ৔޺ޫ,࿯ࢁ޾৴, ʮ୹ण໋ΞϧϑΝઢ์ग़֩छ At-211 ͷ߹ཧత‫͚ͨ޲ʹ੍ن‬ඈࢄ཰ଌఆʯ
, ೔ຊ์ࣹઢ҆શ؅ཧֶձୈ 17 ճֶज़େձ,໊‫ݹ‬԰, 2018 ೥ 12 ݄.
Ӌ৔޺ޫ, ʮཧ‫͚͓ʹݚ‬Δ RI ੡଄Ԡ༻ʙ৽‫ݩ‬ૉͷ୳ࡧ͔Β֩ҩֶͷ਍அɾ࣏ྍ·Ͱʙʯ, ์ࣹઢՊֶϫʔΫγϣοϓʮจཧ‫ڞ‬૑Λֵ৽͢ΔྔࢠϏʔϜՊֶʯ, จ‫۠ژ‬, 2019 ೥ 2 ݄.
Ӌ৔޺ޫ, ʮཧ‫ ݚ‬RI ϏʔϜϑΝΫτϦʔͰ੡଄͢ΔԠ༻‫༻ڀݚ‬ϥδΦΞΠιτʔϓʯ, ཧ‫ݚ‬γϯϙδ΢Ϝʮਫ਼ີ෢૷߅ମͷ߹੒ͱ‫ػ‬ೳධՁʯ
, ઍ୅ా۠, 2019 ೥ 3 ݄.
‫ܓాח‬, ٢໺কੜ, ঙࢠҭ޺, ࢁ࿏ߊ߂, ࠇᖒढ़հ, ԣా༗ҝ, େ‫ڮ‬༤ೋ, ౡఴ݈࣍, ߴ‫ڮ‬ඒ࿨ࢠ, Ӌ৔޺ޫ, ඦ੉හޫ, ߴ‫ߒڮ‬೭, ٢઒জ,
ʮCeBr3 γϯνϨʔλ୯݁থͷେ‫ܕ‬ԽͱΞοηϯϒϦٕज़ͷ։ൃʯ, ୈ 66 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, େా۠, 2019 ೥ 3 ݄.
Ӌ৔޺ޫ, খ৿༗‫ࢠر‬, ԣ๺୎໵, ৿େً, ߴ‫ߒڮ‬೭, ౡఴ݈࣍, ‫ܓాח‬, ඦ੉හޫ, ߴ‫ڮ‬ඒ࿨ࢠ, ʮଟޫࢠΠϝʔδϯά༻ΧϦ΢Ϝ 43ͷ੡଄ٕज़։ൃʯ
, ୈ 66 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, େా۠, 2019 ೥ 3 ݄.
ౡఴ݈࣍, ্ϊொਫ‫ل‬, ߴ‫ߒڮ‬೭, ‫ܓాח‬, ߴ‫ڮ‬ඒ࿨ࢠ, Ӌ৔޺ޫ, ඦ੉හޫ, ʮଟޫࢠଟ෼ࢠ֩ҩֶΠϝʔδϯάٕज़ͷ‫ڀݚ‬։ൃʯ,ୈ 66 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, େా۠, 2019 ೥ 3 ݄.
ߴ‫ڮ‬ඒ࿨ࢠ, ౡఴ݈࣍, େౡ༎հ, ߴ‫ߒڮ‬೭, ‫ܓాח‬, Ӌ৔޺ޫ, ඦ੉හޫ, ʮଟ֩छಉ࣌֩ҩֶΠϝʔδϯάٕज़ͷ։ൃͱ‫ূݕ‬ʯ, ୈ
66 ճԠ༻෺ཧֶձय़‫ֶق‬ज़ߨԋձ, େా۠, 2019 ೥ 3 ݄.
ླ໦݈ଠ, Ӌ৔޺ޫ, ‫ݪ‬ल໌, ฏ໦‫޺و‬, ౻ࢬ྄, ౻ຊ߂೭, 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඙, ʮτϦ΢Ϝ 229 ͷ‫ܭ࣌֩ࢠݪ‬ભҠ෼ޫʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ (2019 ೥), ෱Ԭ,2019 ೥ 3 ݄.
ૣਫ༑༸, ௕ᖛ߂‫ق‬, খᖒ௚໵, అಯ, ‫݈ాݪ‬Ұ, ాத߳௡ੜ, ಺ࢁѪࢠ, ੨໦‫ູو‬, ിࢁԹ, ߴ‫ڮ‬ٛ࿕, Ӌ৔޺ޫ, େલએত, ञ‫ݟ‬ହ‫׮‬,ʮిࢠͷӬ‫ؾిٱ‬૒‫ࢠۃ‬Ϟʔϝϯτ୳ࡧ΁޲͚ͨϑϥϯγ΢Ϝ‫ࢠݪ‬ͷੜ੒ͱτϥοϓʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ (2019 ೥),
෱Ԭ, 2019 ೥ 3 ݄.
ւ໺߂ߦ, Ӌ৔޺ޫ, ‫ݪ‬ल໌, ฏ໦‫޺و‬, ౻ࢬ྄, ౻ຊ߂೭, ླ໦݈ଠ, ּ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඙, ʮ֩‫ڞ‬໐ࢄཚΛ༻͍ͨτϦ΢Ϝ 229 ΞΠιϚʔ४Ґ΁ͷਓ޻తભҠʯ, ೔ຊ෺ཧֶձୈ
74 ճ೥࣍େձ (2019 ೥), ෱Ԭ, 2019 ೥ 3 ݄.
Ӌ৔޺ޫ, ʮ৽‫ݩ‬ૉͷ߹੒ͱԽֶʯ, ୈ 37 ճྔࢠ‫ܥ‬෼ࢠՊֶηϛφʔ, ਆ‫ށ‬, 2019 ೥ 3 ݄.
খ৿༗‫ࢠر‬, Ӌ৔޺ޫ, ԣ๺୎໵, ໼ೲ৻໵, ࠤ౻๬, Ghosh Kaustab, ञ‫ݟ‬ହ‫׮‬, ઒ଜ޿࿨, ʮ206/207/208 Pb(11 B, x)212 Fr ൓Ԡͷྭ‫਺ؔى‬ଌఆͱΫϥ΢ϯΤʔςϧΛ༻͍ͨ Fr ͷࡨ‫ܗ‬੒൓Ԡʯ, ೔ຊԽֶձୈ 99 य़‫ق‬೥ձ 2019, ਆ‫ށ‬, 2019 ೥ 3 ݄.
ԣ๺୎໵, ּদྑਸ, খ৿༗‫ࢠر‬, ౉ᬒӯհ, ΰʔγϡίʔελϒ, Ԧ༸, ৿େً, ࣰ‫ްݪ‬, Ӌ৔޺ޫ, ʮRf ͷེࢎࡨମ‫͚ͨ޲ʹڀݚ‬όον‫ݻܕ‬ӷநग़૷ஔʹΑΔ Zr ‫ ͼٴ‬Hf ͷӄΠΦϯަ‫׵‬ʯ, ೔ຊԽֶձୈ 99 य़‫ق‬೥ձ 2019, ਆ‫ށ‬, 2019 ೥ 3 ݄.
ೋ‫ٶ‬लඒ, ּদྑਸ, ଎ਫᠳ, Ӭ੉কߒ, ॏՏ༏େ, ۙ౻੒ඒ, ౉ᬒӯհ, Ӌ৔޺ޫ, ԣ๺୎໵, খ৿༗‫ࢠر‬, ৿େً, Ԧ༸, ΰʔγϡίʔελϒ, ࠤ౻๬, ࣰ‫ްݪ‬, ʮ102 ൪‫ݩ‬ૉ No ͷΞϯϞχΞਫ‫ͼٴ‬ਫࢎԽφτϦ΢Ϝਫ༹ӷதʹ͓͚ΔαϚϦ΢Ϝ‫ڞ‬௜‫ڍ‬ಈʯ, ೔ຊԽ
ֶձୈ 99 य़‫ق‬೥ձ 2019, ਆ‫ށ‬, 2019 ೥ 3 ݄.
ᜊ౻๖ඒ, ߹઒ਖ਼޾, ࡔ‫ޱ‬ཧ࠸, ӈۙ௚೭, খ৿༗‫ࢠر‬, Ӌ৔޺ޫ, ʮҩྍ༻์ࣹੑ֩छ 169 Yb ੜ੒ͷͨΊͷ nat Er ΁ͷ 50 MeV ΞϧϑΝཻࢠೖࣹʹ͓͚Δੜ੒அ໘ੵଌఆʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥य़ͷ೥ձ, ਫ‫ށ‬, 2019 ೥ 3 ݄.
ԣ๺୎໵, ʮRf ͷེࢎࡨମʹؔ͢Δ‫ڀݚ‬: ಉ଒‫ݩ‬ૉ Zr, Hf, Th Λ༻͍ͨ‫ڀݚૅج‬ʙRf ͷӄΠΦϯަ‫׵‬ʯ
, 2019 ॏ‫ݩ‬ૉ֩ԽֶϫʔΫγϣοϓ, ࿨ޫ, 2019 ೥ 3 ݄.
খ৿༗‫ࢠر‬, ʮFr ͷࡨ‫ܗ‬੒൓Ԡʯ, 2019 ॏ‫ݩ‬ૉ֩ԽֶϫʔΫγϣοϓ, ࿨ޫ, 2019 ೥ 3 ݄.
খ৿༗‫ࢠر‬, ʮSg ͱ Bh ͷ༹ӷԽֶʹ޲͚ͨ GARIS ΨεδΣοτ௚݁‫ܕ‬ਝ଎༹ഔநग़૷ஔͷ։ൃʯ, 2019 ॏ‫ݩ‬ૉ֩ԽֶϫʔΫγϣοϓ, ࿨ޫ, 2019 ೥ 3 ݄.
ԣ๺୎໵, ʮDb ͷϑοԽ෺ࡨମͷ‫ ͚ͨ޲ʹڀݚ‬Nb, Ta, Pa Λ༻͍ͨ HF/HCl ‫ܥ‬ͷΠΦϯަ‫ޙࠓͼٴ׵‬ͷ‫ܭڀݚ‬ըʯ, 2019 ॏ‫ݩ‬ૉ֩ԽֶϫʔΫγϣοϓ, ࿨ޫ, 2019 ೥ 3 ݄.
W. Yang, “Gas-phase chemistry of technetium and rhenium carbonyl complexes with short-lived isotopes,” 2019 ॏ‫ݩ‬ૉ֩ԽֶϫʔΫγϣοϓ, ࿨ޫ, 2019 ೥ 3 ݄.
W. Yang, “Mass spectrometric speciation of metal-carbonyls in the gas phase,” 2019 ॏ‫ݩ‬ૉ֩ԽֶϫʔΫγϣοϓ, ࿨ޫ, 2019 ೥ 3 ݄.

Posters Presentations[International Conference etc.]
T. Niwase, K. Fujita, Y. Yamano, K. Watanabe, D. Kaji, K. Morimoto, H. Haba, T. Hirano, S. Mitsuoka, K. Morita, “Measuremet of fusion
barrier distribution in 51 V + 208 Pb system,” 13th International Conference on Nucleus-Nucleus Collisions, Omiya, Japan, December,
2018.

[Domestic Conference]ۙ౻੒ඒ, ּদྑਸ, Ӭ੉কߒ, ҆ా༐ً, ॏՏ༏େ, େ಺Ꮺً, ਆాߊॆ, ೋ‫ٶ‬लඒ, ౉ᬑӯհ, Ӌ৔޺ޫ, ‫ٱ‬อ໦༞ੜ, খ৿༗‫ࢠر‬, ԣ๺୎໵, ໼ೲ৻໵, ࠤ౻๬, ࣰ‫ްݪ‬, ʮRf ͷԘࢎ‫Ͱܥ‬ͷ༹ഔநग़‫ڍ‬ಈͷ༗‫༹ػ‬ഔґଘੑʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫౎ژ‬, 2018 ೥ 9 ݄.
઒㟒߁ฏ, ৽༟‫ت‬, ੨Ҫ‫౎ܠ‬, ࿯ࢁ޾৴, ੢தҰ࿕, Ӌ৔޺ޫ, ໼ೲ৻໵, ԣࢁ໌඙, ʮϥυϯΨεີ෧γϦϯδΛར༻ͨ͠ Rn-At δΣωϨʔλʔγεςϜͷ։ൃʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫౎ژ‬, 2018 ೥ 9 ݄.
৽༟‫ت‬, ઒࡚߁ฏ, ੨Ҫ‫౎ܠ‬, ԣࢁ໌඙, ࿯ࢁ޾৴, ੢தҰ࿕, ໼ೲ৻໵, Ӌ৔޺ޫ, ʮ211 Rn-211 At δΣωϨʔλʔ։ൃͷͨΊͷΞελ
νϯ༹ഔநग़ͷ‫—ڀݚ‬131 I ͱͷநग़‫ڍ‬ಈͷൺֱ‫ࢎͼٴ‬ԽࡎͷޮՌͷௐࠪ—ʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)ձ, ‫౎ژ‬, 2018 ೥ 9 ݄.
Ӎ૔‫ܒ‬, ळࢁ࿨඙, ‫ٱ‬෌໦ࢤ࿠, Ӌ৔޺ޫ, ʮۚଐ಺แϑϥʔϨϯ߹੒࣮‫ݧ‬ͷͨΊͷແ୲ମ 139 Ce τϨʔαʔͷௐ੡ʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫౎ژ‬, 2018 ೥ 9 ݄.
ࣰ‫ްݪ‬, ٢ଜਸ, ๛ౢް࢙, ݉ాՃचࢠ, ுࢠ‫ݟ‬, Ӭాޫ஌࿠, ౉෦௚࢙, େߐҰ߂, ാᖒॱ, ࢁଜே༤, ന࡚‫࣍ݠ‬, ٠Ӭӳण, Ӌ৔޺ޫ,࿯ࢁ޾৴, ʮ୹ण໋ α ઢ֩छͷ߹ཧత‫੍ن‬ͷͨΊͷσʔλऔಘʹΑΔ҆શੑ‫҆ͱূݕ‬શ؅ཧɾ‫ڭ‬ҭํ๏ͷ։ൃʯ, 2018 ೔ຊ์ࣹԽֶձ೥ձɾୈ 62 ճ์ࣹԽֶ౼࿦ձ, ‫౎ژ‬, 2018 ೥ 9 ݄.
ࡔ‫ޱ‬ཧ࠸, ߹઒ਖ਼޾, খ৿༗‫ࢠر‬, Ӌ৔޺ޫ, ʮ89 Y ඪత΁ͷॏཅࢠೖࣹ൓ԠʹΑΔ 89 Zr ੜ੒൓Ԡஅ໘ੵʯ, 2018 ೥౓֩σʔλ‫ڀݚ‬ձ, ໨ࠇ۠, 2018 ೥ 11 ݄.
ԣ๺୎໵, ʮΞϧϑΝઢ֩ҩֶ࣏ྍ༻֩छΞελνϯʔ 211 ͷ੡଄։ൃʯ, Chemical Probe ߹॓‫ࣜܗ‬ηϛφʔ, ઍ༿, 2018 ೥ 10 ݄.
݉ా (தౡ) Ճचࢠ, ࣰ‫ްݪ‬, ٢ଜਸ, ๛ౢް࢙, ுࢠ‫ݟ‬, Ӭాޫ஌࿠, ౉෦௚࢙, େߐҰ߂, ࢁଜே༤, ന࡚‫࣍ݠ‬, ٠Ӭӳण, Ӌ৔޺ޫ,࿯ࢁ޾৴, ʮಈ෺࣮‫͚͓ʹݧ‬Δ୹ण໋ΞϧϑΝઢ֩छͷମ಺֎ͷ෼෍ʯ, ೔ຊ์ࣹઢ҆શ؅ཧֶձୈ 17 ճֶज़େձ, ໊‫ݹ‬԰, 2018
೥ 12 ݄.
Ӭాޫ஌࿠, ٢ଜਸ, ๛ౢް࢙, ࣰ‫ްݪ‬, ݉ా (தౡ) Ճचࢠ, ுࢠ‫ݟ‬, ౉෦௚࢙, େߐҰ߂, ࢁଜே༤, ന࡚‫࣍ݠ‬, ٠Ӭӳण, Ӌ৔޺ޫ,࿯ࢁ޾৴, ʮ୹ण໋ α ઢ์ग़֩छͷ߹ཧత‫੍ن‬ͷͨΊͷϥδ΢Ϝ-223 ͓Αͼͦͷࢠଙ֩छͷඈࢄ཰౳ͷଌఆʯ, ೔ຊ์ࣹઢ҆શ؅ཧֶձୈ 17 ճֶज़େձ, ໊‫ݹ‬԰, 2018 ೥ 12 ݄.
ଜ্Үే, ฏ઒‫ܒو‬, ಺౻Նथ, ࡔ‫ޱ‬૱ࢤ, ౻ా‫܇‬༟, ‫৻ڷ‬ଠ࿠, ଍ཱஐ, ాத੟ਉ, ాதହ‫و‬, ఉ੉‫ོڿ‬, ৿ຊ޾࢘, Ӌ৔޺ޫ, Ճ࣏େ࠸, അ৔ल஧, Pierre Brionnet, ໦ଜ૑େ, ञҪӳߦ, ৿ాߒհ, ʮ௒ॏ‫ݩ‬ૉࣝผͷͨΊͷσʔλղੳख๏ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ
74 ճ೥࣍େձ (2019 ೥), ෱Ԭ, 2019 ೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 the old 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 June 2018, the eighth IN-PAC met and approved one fee-based proposal from a new private company. In January 2019, IN-PAC
reviewed by e-mail one fee-based continuing proposal from a private company and approved it. In July 2018, a fee-based beamtime
was performed with a Kr-84 (70 MeV/nucleon) and an Ar-40 (95 MeV/nucleon) beam at the E5A beamline. In December 2018, a
fee-based beamtime was performed with a Kr-86 (66 MeV/nucleon) beam at the E3A beamline. The clients used the beam to simulate
single-event eﬀects of space-use semiconductors 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 quality of the beam used for the semiconductor irradiations. Before eachbeam time, we measure the properties of the beam; the dependence of the beam energy on the degrader thickness, the beam LETdistribution 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 produced by nuclear reactions in the materials. We study the beam impurity using
radiochemical measurements and compared the results with simulations by the PHITS code. In 2018, the results were reported at theIEEE international conference and were shared with the clients.
(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), Cd109 (463 days), Y-88 (107 days) and Sr-85 (65 days) which are produced at the AVF cyclotron by the nuclear chemistry researchteam. 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 2018, we started distribution of new RI Cu-67 (62 hours). We delivered one shipment of Cu-67 with an activity of 5 MBq, 3
shipments of Zn-65 with a total activity of 9 MBq and 3 shipments of Y-88 with an activity of 3 MBq. The final recipients of the RIs
are universities, research institutes and medical research centers.
(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 2018, 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. 52 (2019)

Members
Team Leader
Atsushi YOSHIDA
Contract Researcher
Tadashi KAMBARA
Technical Staﬀ I
Daiki MORI (concurrent: RI Application Team)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
A. Yoshida, ʮ21.5.1 RI Ϗ-ϜʹΑΔϦΞϧλΠϜຎ໣ࢼ‫ݧ‬ʯ, ೔ຊՃ଎‫ֶث‬ձஶ Ճ଎‫ث‬ϋϯυϒοΫ 21 ষ฻Β͠ʹ໾ཱͭՃ଎‫ث‬
ٕज़ 21.5 Խֶ޻‫ۀ‬ɾ޻‫ٕۀ‬ज़, ‫ؙ‬ળग़൛ 2018 ೥ 4 ݄, ISBN 978-4-621-08901-9.
T. Kambara, A. Yoshida, “Facility for Heavy-Ion Irradiation of Semiconductors at RIKEN RI-Beam Factory,” 2018 IEEE Radiation
Eﬀects Data Workshop (REDW) Workshop Record, pg.94, DOI: 10.1109/NSREC.2018.8584278.

Oral Presentations[International Conference etc.]
A. Yoshida, “Wear diagnostics using low-energy RIBs and their γ-ray imaging,” Technical Meeting on Novel Multidisciplinary Applications with Unstable Ion Beams and Complementary Techniques, International Atomic Energy Agency (IAEA), Wien Austria,
December 10–14, 2018.

Posters Presentations[International Conference etc.]
T. Kambara, A. Yoshida, “Facility for heavy-ion irradiation of semiconductors at RIKEN RI-Beam Factory,” 2018 IEEE Radiation Eﬀects
Data Workshop (REDW) Workshop, July 19, 2018.

Patents
A. Yoshida, T. Kambara, R. Uemoto, A. Nagano, H. Uno, N. Takahashi, “Wear diagnostics method and instrument,” 2015-1490 patentapplied.
T. Kambara, A. Yoshida, H. Takeichi, “Gamma-ray measurement method and instrument,” 2014-034417, patent registered.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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) 10th order QED calculation and the lepton anomalous magnetic moments
First preliminary value of the tenth-order QED contribution to the electron anomalous magnetic moment ae = (g − 2)/2 wasreported by us in 2012. Since then, we have been improving and establishing its accuracy: We reevaluated the most diﬃcult and large
set of the Feynman diagrams by using advanced techniques of numerical calculation especially suitable to RIKEN’s supercomputer.
As a result, we have obtained precise values for the eighth- and tenth-order terms. Assuming the validity of the standard model, it
leads to the world-best value of the fine-structure constant α−1 (ae ) = 137.035 999 1570(29)(27)(18)(331), where uncertainties are fromthe eighth-order term, tenth-order term, hadronic and electroweak terms, and the experimental measurement of ae . This is the mostprecise value of α available at present in the world and provides a stringent constraint on possible theories beyond the standard model.
(1-2) Picard-Lefschetz theory and the sign problem
Understanding strongly-correlated quantum field theories and many-body systems has been one of the ultimate goals in contemporary physics. Exact diagonalization of a Hamiltonian provides us with complete information on the system; however, it usuallyrequires the huge computational cost and is limited to small systems. For large systems, numerical simulation on discretized spacetime lattice with quantum Monte Carlo method is a powerful ab initio tool based on the importance sampling. In many quantum
systems of great interest, however, it suﬀers from the so-called sign problem; large cancellation occurs between positive and negative
quantities to obtain physical signals, so that the computational time grows exponentially with the system size. So far, many attempts
have been proposed overcome the sign problem, which include the two promising candidates, the complex Langevin method and the
Lefschetz-thimble method. In particular, the Lefschetz-thimble approach is a generalization of the steepest descent method for multiple oscillatory integrals. In the past few years, we have studied extensively the mathematical basis of the Lefschetz-thimble method
as well as its practical applications to quantum systems such as the real-time path integral for quantum tunneling, zero-dimensionalbosonic and fermionic models, the one-site Hubbard model, and Polyakov-loop eﬀective models for QCD. We have shown that theinterference among multiple Lefschetz thimbles is important to reproduce the general non-analytic behavior of the observables as afunction of the external parameter. Such an interference is a key to understand the sign problem of finite-density QCD.
(1-3) Functional renormalization group• BEC-BCS crossover in cold fermionic atoms
We have developed a fermionic functional renormalization group (FRG) and applied this method to describe the superfluid phasetransition of the two-component fermionic system with an attractive contact interaction. The connection between the fermionic FRG
approach and the conventional Bardeen-Cooper-Schrieﬀer (BCS) theory with Gorkov and Melik-Barkhudarov (GMB) correction wasclarified in the weak coupling region by using the renormalization group flow of the fermionic four-point vertex with particle-particle
and particle-hole scatterings. To go beyond the BCS + GMB theory, coupled FRG flow equations of the fermion self-energy andthe four-point vertex are studied under an Ansatz concerning their frequency/momentum dependence. We found that the fermion
self-energy turns out to be substantial even in the weak coupling regime, and the frequency dependence of the four-point vertex isessential to obtain the correct asymptotic-ultraviolet behavior of the flow for the self-energy. The superfluid transition temperature andthe associated chemical potential were evaluated in the region of negative scattering lengths.
• Tricritical point of the superconducting transition
The order of the phase transition in the Abelian Higgs model with complex scalar fields became of interest because of the analysesof the spontaneous symmetry breaking due to radiative corrections in 3 + 1 dimensions, and of a superconductor near the critical pointwith the dimensionally reduced Ginzburg-Landau theory. Indeed, the fluctuations of the gauge field were of great importance andmay even turn the second-order transition to first-order at least for strongly type-I superconductors. We analyzed the order of the- 357 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)superconducting phase transition via the functional renormalization group approach: We derived for the first time fully analytic
expressions for the β functions of the charge and the self-coupling in the Abelian Higgs model with N-component scalar field in d = 3
dimensions. The result supports the existence of two charged fixed-points: an infrared (IR) stable fixed point describing a secondorder phase transition and a tricritical fixed point controlling the region of the parameter space that is attracted by the former one. It
was found that the region√ separating first and second-order transitions can be uniquely characterized by the critical Ginzburg-Landauparameter, κc ≈ 0.62/ 2 for N = 1.
• Chiral dynamics under strong magnetic field
The magnetic field is not only interesting as a theoretical probe to the dynamics of QCD, but also important in cosmology and astrophysics: A class of neutron stars called magnetars has a strong surface magnetic field of order 1010 T while the primordial magnetic
field in early Universe is estimated to be even as large as ∼1019 T. In non-central heavy-ion collisions at RHIC and LHC, a magnetic
field of the strength ∼1015 T perpendicular to the reaction plane could be produced and can have impact on the thermodynamics
and transport properties of the quark-gluon plasma. We investigated the quark-meson model in a magnetic field using the functional
renormalization group equation beyond the local-potential approximation. We considered anisotropic wave function renormalization
for mesons in the eﬀective action, which allows us to investigate how the magnetic field distorts the propagation of neutral mesons.
We found that the transverse velocity of mesons decreases with the magnetic field at all temperatures. Also, the constituent quark
mass is found to increase with magnetic field, resulting in the crossover temperature that increases monotonically with the magnetic
field.
(1-4) Emergent spacetime
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. A recent example is the SO(2, 4) symmetry in AdS/CFT
correspondence which leads to unexpected connection between gravity and gauge theory defined in diﬀerent dimensions. We oﬀer
another example of quantum field theory where symmetry plays a central role and reveals interesting phenomena: Our focal point is
the global conformal symmetry in two dimensional conformal field theory (2d CFT), which is homomorphic to SL(2, R). We haveshown that 2d CFT admits a novel quantization which we call dipolar quantization. Usually the study of the quantum field theory
starts by defining the spacetime where the field is situated. On the other hand, in our case, we first obtain quantum system and then
the nature of spacetime emerges. This is in accordance with the general ideas of emergent spacetime such as those discussed in matrix
models.
(2) Theory of spontaneous symmetry breaking(2-1) Dispersion relations of Nambu-Goldstone modes at finite temperature and density
We clarified the dispersion relations of Nambu-Goldstone (NG) modes associated with spontaneous breaking of internal symmetries at finite temperature and/or density. We showed that the dispersion relations of type-A and type-B NG modes are linear andquadratic in momentum, whose imaginary parts are quadratic and quartic, respectively. In both cases, the real parts of the dispersion
relations are larger than the imaginary parts when the momentum is small, so that the NG modes can propagate for long distances.
We derived the gap formula for NG modes in the presence of explicit symmetry breaking. We also discussed the gapped partners oftype-B NG modes, when type-A and type-B NG modes coexist.
(2-2) Eﬀective field theory for spacetime symmetry breaking
We studied the eﬀective field theory for spacetime symmetry breaking from the local symmetry point of view. By gauging spacetime symmetries, the identification of Nambu-Goldstone (NG) fields and the construction of the eﬀective action were performed basedon the breaking pattern of diﬀeomorphism, local Lorentz, and isotropic Weyl symmetries as well as the internal symmetries including
possible central extensions in nonrelativistic systems. Such a local picture provides a correct identification of the physical NG fields,
while the standard coset construction based on global symmetry breaking does not. We also revisited the coset construction for spacetime symmetry breaking: Based on the relation between the Maurer-Cartan one-form and connections for spacetime symmetries, weclassified the physical meanings of the inverse Higgs constraints by the coordinate dimension of broken symmetries. Inverse Higgs
constraints for spacetime symmetries with a higher dimension remove the redundant NG fields, whereas those for dimensionlesssymmetries can be further classified by the local symmetry breaking pattern.
(2-3) Nambu-Goldstone modes in dissipative systems
Spontaneous symmetry breaking (SSB) in Hamiltonian systems is a universal and widely observed phenomena in nature, e.g., theelectroweak 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. The translational symmetry in the reaction
diﬀusion system is spontaneously broken by a spatial pattern formation such as the Turing pattern in biology. The rotational symmetryis spontaneously broken in the active hydrodynamics which describes collective motion of biological organisms. We found that there
exist two types of NG modes in dissipative systems corresponding to type-A and type-B NG modes in Hamiltonian systems. By taking
the O(N) scalar model obeying a Fokker-Planck equation as an example, we have shown that the type-A NG modes in the dissipative
system are diﬀusive modes, while they are propagating modes in Hamiltonian systems. We pointed out that this diﬀerence is causedby the existence of two types of Noether charges, Qα R and Qα A : Qα R are symmetry generators of Hamiltonian systems, which are
not generally conserved in dissipative systems. Qα A are symmetry generators of dissipative systems described by the Fokker-Planck
equation and are conserved. We found that the NG modes are propagating modes if Qα R are conserved, while those are diﬀusivemodes if they are not conserved.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(3) Lattice gauge theory(3-1) Hadron interactions from lattice QCD
One of the most important goals in nuclear physics is to determine baryon-baryon interactions directly from QCD. To achieve thisgoal, the HAL QCD Collaboration has been developing a novel lattice QCD formulation (HAL QCD method) and performing firstprinciples numerical simulations. We have calculated the spin-orbit forces for the first time from QCD by the HAL QCD method, andhave observed the attraction in the 3 P2 channel related to the P-wave neutron superfluidity in neutron star cores. Our calculation of the
N-Ω interaction shows that this system is bound in the 5 S2 channel. We have shown that the Ω-Ω interaction in the spin-singlet channel
is in the unitary region where the scattering length becomes large. Three-nucleon forces have been calculated for several heavy quark
masses. Our lattice calculations was extended to the heavy quark systems, e.g. the exotic tetraquark, T cc and T cs . Properties of thelight and medium-heavy nuclei (4 He, 16 O, 40 Ca) have been calculated by combining the nuclear many-body techniques and the nuclear
forces obtained from lattice QCD. Also, we have theoretically and numerically shown that the Luscher’s method traditionally used instudying the hadron-hadron interactions does not lead to physical results for baryon-baryon interactions unless the lattice volume isunrealistically large, so that the HAL QCD method is the only reliable approach to link QCD to nuclear physics.
As a part of the High Performance Computing Infrastructure (HPCI) Project 5, we have completed the generation of (2 + 1)-flavor
full QCD configurations with a large box, V = (8 fm)3 , and with nearly physical pion mass, 145 MeV, on the 10 Pflops super computer“K.” We are currently in the process of calculations of baryon-baryon interactions using these configurations.
(3-2) Momenta and Angular Momenta of Quarks and Gluons inside the Nucleon
Determining the quark and gluon contributions to the spin of the nucleon is one of the most challenging problems in QCD bothexperimentally and theoretically. Since the quark spin is found to be small (∼ 25% of the total proton spin) from the global analysis
of deep inelastic scattering data, it is expected that the rest should come from the gluon spin and the orbital angular momenta ofquarks and gluons. We made state-of-the-art calculations (with both connected and disconnected insertions) of the momenta and theangular momenta of quarks and gluons inside the proton. The u and d quark momentum/angular momentum fraction extrapolated tothe physical point is found to be 0.64(5)/0.70(5), while the strange quark momentum/angular momentum fraction is 0.024(6)/0.023(7),and that of the gluon is 0.33(6)/0.28(8). This implies that the quark spin carries a fraction of 0.25(12) of the proton spin. Also, we
found that the quark orbital angular momentum, which turned out to be dominated by the disconnected insertions, constitutes 0.47(13)of the proton spin.
(4) QCD under extreme conditions(4-1) Production and Elliptic Flow of Dileptons and Photons in the semi-Quark Gluon Plasma
A notable property of peripheral heavy-ion collisions at RHIC and LHC is the elliptic flow which is a measure of the transfer
of initial spatial anisotropy to momentum anisotropy. Both the PHENIX experiment at RHIC and the ALICE experiment at LHC
have announced a puzzling observation; a large elliptic flow for photons, comparable to that of hadrons. We considered the thermal
production of dileptons and photons at temperatures above the QCD critical temperature (T c ) on the basis of semi-QGP, a theoreticalmodel for describing the quark-gluon plasma (QGP) near T c . With realistic hydrodynamic simulations, we have shown that the strong
suppression of photons in semi-QGP due to the inhibition of colored excitations tends to bias the elliptical flow of photons to thatgenerated in the hadronic phase. This increases the total elliptic flow for thermal photons significantly towards the experimental data.
(4-2) Deriving relativistic hydrodynamics from quantum field theory
Hydrodynamics describes the spacetime evolution of conserved quantities, such the energy, the momentum, and the particle
number. It does not depend on microscopic details of the system, so that it can be applied to many branches of physics from condensed
matter to high-energy physics. One of the illuminating examples is the recent success of relativistic hydrodynamics in describing
the evolution of QGP created in heavy-ion collisions. Inspired by the phenomenological success of relativistic hydrodynamics indescribing QGP, theoretical derivations of the relativistic hydrodynamics have been attempted on the basis of the kinetic theory,the fluid/gravity correspondence, the non-equilibrium thermodynamics, and the projection operator method. In our study, a mostmicroscopic and non-perturbative derivation of the relativistic hydrodynamics from quantum field theory was given on basis of thedensity operator with local Gibbs distribution at initial time. Performing the path-integral formulation of the local Gibbs distribution,
we derived the generating functional for the non-dissipative hydrodynamics microscopically. Moreover, we formulated a procedure toevaluate dissipative corrections.
(4-3) Hadron-quark crossover in cold and hot neutron stars
We studied bulk properties of cold and hot neutron stars (NS) on the basis of the hadron-quark crossover picture where a smoothtransition from the hadronic phase to the quark phase takes place at finite baryon density. By using a phenomenological equation ofstate (EOS) “CRover” which interpolates the two phases at around 3 times the nuclear matter density (ρ0 ), it is found that the cold
NSs with the gravitational mass larger than two solar mass can be sustained. This is in sharp contrast to the case of the first-order
hadron-quark transition. The radii of the cold NSs with the CRover EOS are in the narrow range (12.5 ± 0.5) km which is insensitive
to the NS masses. Due to the stiﬀening of the EOS induced by the hadron-quark crossover, the central density of the NSs is at most
4ρ0 and the hyperon-mixing barely occurs inside the NS core. This constitutes a solution of the long-standing hyperon puzzle firstpointed out by Takatsuka et al. The eﬀect of color superconductivity (CSC) on the NS structures was also examined with the hadronquark crossover picture. For the typical strength of the diquark attraction, a slight softening of the EOS due to two-flavor CSC takes
place and the maximum mass is reduced by about 0.2 solar mass. The CRover EOS is generalized to the supernova matter at finite
temperature to describe the hot NSs at birth. The hadron-quark crossover was found to decrease the central temperature of the hot NSs
under isentropic condition. The gravitational energy release and the spin-up rate during the contraction from the hot NS to the cold
NS were also estimated.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(5) Nuclear and atomic many-body problems(5-1) Giant dipole resonance in hot nuclei
Over the last several decades, extensive experimental and theoretical works have been done on the giant dipole resonance (GDR)
in excited nuclei covering a wide range of temperature (T ), angular momentum (J) and nuclear mass. A reasonable stability of the
GDR centroid energy and an increase of the GDR width with T (in the range ∼1–3 MeV) and J are the two well-established results.
Some experiments have indicated the saturation of the GDR width at high T : The gradual disappearance of the GDR vibration atmuch higher T has been observed. Experiments on the Jacobi transition and the GDR built on superdeformed shapes at high rotationalfrequencies have been reported in a few cases. We have demonstrated that thermal pairing included in the phonon damping model(PDM) is responsible for the nearly constant width of GDR at low temperature T < 1 MeV. We have also shown that the enhancement
observed in the recent experimentally extracted nuclear level densities in 104 Pd at low excitation energy and various angular momenta
is the first experimental evidence of the pairing reentrance in finite (hot rotating) nuclei. The results of calculations within the PDM
were found in excellent agreement with the latest experimental data of GDR in the compound nucleus 88 Mo.
(5-2) Hidden pseudospin symmetries and their origins in atomic nuclei
The quasi-degeneracy between single-particle orbitals, (n, l, j = l+1/2) and (n−1, l+2, j = l+3/2), indicates a hidden symmetry
in atomic nuclei, the so-called pseudospin symmetry (PSS). Since the introduction of the concept of PSS in atomic nuclei, there havebeen comprehensive eﬀorts to understand its origin. Both splittings of spin doublets and pseudospin doublets play critical roles in theevolution of magic numbers in exotic nuclei discovered by modern spectroscopic studies with radioactive ion beam facilities. Since
the PSS was recognized as a relativistic symmetry in 1990s, many special features, including the spin symmetry (SS) for anti-nucleon,
and other new concepts have been introduced. We have published a comprehensive review article (Liang et al., Phys. Rept. 2015)
on the PSS and SS in various systems, including extensions of the PSS study from stable to exotic nuclei, from non-confining toconfining potentials, from local to non-local potentials, from central to tensor potentials, from bound to resonant states, from nucleon
to anti-nucleon spectra, from nucleon to hyperon spectra, and from spherical to deformed nuclei. We also summarized open issues inthis field, including the perturbative nature, the supersymmetric representation with similarity renormalization group, and the puzzle
of intruder states.
(5-3) Efimov Physics in cold atoms
For ultra-cold atoms and atomic nuclei, the pairwise interaction can be resonant. Then, universal few-body phenomena such as
the Efimov eﬀect may take place. We carried out an exploratory study suggesting that the Efimov eﬀect can induce stable many-bodyground states whose building blocks are universal clusters. We identified a range of parameters in a mass and density imbalanced
two-species fermionic mixture for which the ground state is a gas of Efimov-related universal trimers. An explicit calculation of thetrimer-trimer interaction reveals that the trimer phase is an SU(3) Fermi liquid stable against recombination losses. We proposed toexperimentally observe this phase in a fermionic mixture of 6 Li-53 Cr atoms. We have also written a comprehensive review article ontheoretical and experimental advances in Efimov physics.
(5-4) Supersymmetric Bose-Fermi mixtures
Some special Bose-Fermi mixtures of cold atoms and molecules in optical lattices could be prepared in such a way as they exhibit
approximate supersymmetry under the interchange of bosons and fermions. Since supersymmetry is broken at finite temperature
and/or density, an analog of the Nambu-Goldstone excitation, dubbed the “Goldstino,” should appear. We evaluated the spectral
properties of the Goldstino in a Bose-Fermi mixture of cold atoms and molecules. We derived model independent results from sum
rules obeyed by the spectral function. Also, by carrying out specific calculations with random phase approximation, analytic formulafor the dispersion relation of Goldstino at small momentum was obtained.

Members
Group 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)

Nishina Center Research Scientists
Makiko NIO

Dang NGUYEN DINH

Special Postdoctoral Researchers
Shinya GONGYO
Matthias Wilhelm Georg BERWEIN

Takahiro DOI
Tomoya HAYATA- 360 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Postdoctoral Researcher
Takumi IRITANIInternational Program Associate
Jie LIU (Nanjing Univ.)
Visiting Researcher
Hiroyuki TAJIMA (JSPS Fellow)
Senior Visiting Scientist
Koichi YAZAKI (Univ. of Tokyo)
Visiting Scientists
Noriyoshi ISHII (Osaka Univ.)
Tatsuyuki TAKATSUKA (Iwate Univ.)
Motoi TACHIBANA (Saga Univ.)
Kanabu NAWA (Univ. of Tokyo Hospital)
Masashi HAYAKAWA (Nagoya Univ.)
Gergely FEJOS (Keio Univ.)
Kenji SASAKI (Kyoto Univ.)
Takashi SANO (AIST)
Tatsumi AOYAMA (KEK)
Takashi INOUE (Nihon Univ.)
Shinya AOKI (Kyoto Univ.)
Kenji MORITA (QST)
Hiroshi SUZUKI (Kyushu Univ.)
Sachiko TAKEUCHI (Japan College of Social Work)
Kenji FUKUSHIMA (Univ. of Tokyo)
Toshifumi NOUMI (Kobe Univ.)
Atsushi NAKAMURA (Hiroshima Univ.)
Takayuki MATSUKI (Tokyo Kasei Univ.)
Takeo INAMI (Sungkyunkwan Univ.)
Nodoka YAMANAKA ( IPN Orsay)

Hung NGUYEN (Duy Tan University)
Rhine Kumar Arayakkandi Keechiprath (Cochin Univ. of Sci.
and Tech.)
Koji HASHIMOTO (Osaka Univ.)
Yoichi KAZAMA (Univ. of Tokyo)
Keiko MURANO (Osaka Univ.)
Di-Lun YANG (Kyoto Univ.)
Daisuke KADOH (Keio Univ.)
Yoji OHASHI (Keio Univ.)
Minoru ETO (Yamagata Univ.)
Takashi NAKATSUKASA (Tsukuba Univ.)
Yoichi IKEDA (Osaka Univ.)
Hiroshi TOKI (Osaka Univ.)
Norisuke SAKAI (Keio Univ.)
Tetsuo MATSUI (The Open Univ. of Japan)
Masaki MURATA (Univ. of Tokyo Hospital)
Kazuo FUJIKAWA (Univ. of Tokyo)
Makoto TAKIZAWA (Showa Pharm. Univ.)
Shoichi SASAKI (Tohoku Univ.)

Student Trainees
Takaya MIYAMOTO (Kyoto Univ.)
Hikaru SAKAKIBARA (Univ. of Tokyo)
Tan Phuc LE (Univ. of Sci., Vietnam National Univ.)
Zhiheng WANG (Tsukuda Univ.)
Asahi CHIKAOKA (Univ. of Tokyo)

Yixin GUO (USTC)
Daisuke OHASHI (Univ. of Tokyo)
Yutaro AKAHOSHI (Kyoto Univ.)
Tomoya NAITO (Univ. of Tokyo)- 361 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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) To investigate the eﬀect of T = 3/2 three-body force, we have studied super heavy hydrogen system, 5 H as a five-bodysystem. In this calculation, we employ several realistic forces and calculate resonant state. As a result, without T = 3/2
three-body force, we reproduce the experimental data.
(2) Motivated by observed data of pentaquark system by LHCb, we studied this system as a five-boy system within the frameworkof non-relativistic constituent quark model. It was diﬃcult to describe the experimental data. It would be indicated that theobserved state should be meson-baryon resonant state which we are not able to calculate with the present framework.
(3) We calculate 9Λ Be within the framework of ααΛ three-body model. We obtain many resonant states above 5Λ He + α threshold. Furthermore, we categorized 8 Be analog, genuine hypernuclear analog, and 9 Be analog which are consistent with pastcalculation by Motoba et al.

Members
Group Director
Emiko HIYAMA
Special Postdoctoral Researchers
Hajime TOGASHI
Kadir Utku CAN

Yasuhiro YAMAGUCHI

Postdoctoral Researcher
Dalibor SKOUPIL
Junior Research Associate
Jehee LEE (Tokyo Tech.)
Visiting Scientists
Masayuki ASAKAWA (Osaka Univ.)
Akinobu DOTE (KEK)
Yasuro FUNAKI (Kanto Gakuin Univ.)
Kazuma NAKAZAWA (Gifu Univ.)
Takayuki MYO (Osaka Inst. of Tech.)
Ying ZHANG (Tianjin Univ.)
Hidekatsu NEMURA (Osaka Univ.)
Toru SATO (Osaka Univ.)
Taiichi YAMADA (Kanto Gakuin Univ.)
Shimpei ENDO (Tohoku Univ.)
Takenori FURUMOTO (Yokohama National Univ.)
Jinniu HU (Nankai Univ.)
Yasuo YAMAMOTO (Tsuru Univ.)
Philipp GUBLER (JAEA)
Makoto OKA (JAEA)
Wolfram WEISE (TUM)
Atsushi UMEYA (Nihon Inst. of Tech.)Toshio MOTOBA (Osaka Elec.-Com. Univ.)
Tetsuo HYODO (Kyoto Univ.)
Masahiro ISAKA (Hosei Univ.)
Daisuke JIDO (Tokyo Tech.)
Shuichi GOJUKI (SGI Japan Ltd.)
Soichi ISHIKAWA (Hosei Univ.)
Hyun-Chul KIM (Inha Univ.)
Thomas Adriaan RIJKEN (Univ. Nijmegen)
Xian-Rong ZHOU (East China Normal Univ.)
Atsushi HOSAKA (Osaka Univ.)
Petr VESELY (Academy of Science of Czech Rep.)
Shoji SHINMURA (Gifu Univ.)
Kei KOTAKE (Fukuoka Univ.)Hans-Josef SCHULZE (INFN)
Dalibor SKOUPIL (Kyushu Unvi.)
Jean-Marc RICHARD (Lyon Univ.)
Masanobu YAHIRO (Kyushu Unvi.)- 362 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Tingting SUN (Zhengzhou Univ.)
Lorenzo CONTESSI (Hebrew Univ. of Jerusalem)
Ulugbek YAKHSHIEV (Inha Univ.)
Satoshi NAKAMURA (Tohoku Univ.)
Shin WATANABE (National Inst. of Tech., Gifu College)
Satoru HIRENZAKI (Nara Women’s Univ.)

Jirina STONE (Univ. of Tennessee Knoxville)
Tomokazu FUKUDA (Osaka Elec.-Com. Univ.)
Jiwei CUI (Xidian Univ.)
Kiyomi IKEDA (Niigata Univ.)
Chengjun XIA (Zhejiang University)

Student Trainees
Saori MAEDA (Tokyo Tech.)
Jie LIU (Nanjing Univ.)
Christiane SCHMICKLER (TU Darmstadt)

Kongyi HU (Nankai Univ.)
Qian WU (Nanjing Univ.)
Qi MENG (Nanjing Univ.)

Part-time Worker
Yoko FUJITA

List of Publications & Presentations
Publications[Book]K. U. Can, “Electromagnetic Form Factors of Charmed Baryons in Lattice QCD, Springer Theses Series,” (Springer, Singapore, 2018).

[Journal](Original Papers) *Subject to Peer Review
E. Hiyama, K. Nakazawa, “Structre of S = −2 hypernuclei and hyperon-hyperon interaction,” Annual Review of Nuclear and Particle
Science and Particle Science 68 (2018).
Y. Shimizu, Y. Yamaguchi, M. Harada, “Heavy quark spin multiplet structure of P̄(∗) Σ(∗)
Q molecular states,” Phy. Rev. D 98, 014021 (2018).
E. Hiyama, M. Kamimura, “Study of various few-body systems using Gaussian expansion method (GEM),” Frontiers of Physics 13,(2018).
E. Hiyama,A. Hosaka, M. Oka, J. M. Richard, “Quark model estimate of hidden-charm pentaquark resonances,” Phy. Rev. C, 10, 1103/Phy.
Rev. C 98, 045208, 98 (2018).
H. Togashi, K. Nakazato, Y. Takehara, S. Yamamuro, H. Suzuki, M. Takano, “Supernova equation of state based on realistic nuclear
forces,” RIKEN RIKEN Accel. Prog. Rep. 51 (2018). (Highlights of the year ʹબग़)
U. Yakhshiev, H. C. Kim, E. Hiyama, “Instanton eﬀects on charmonium states,” Phy. Rev. D 98, 114036 (2018).
H. Bahtiyar, K. U. Can, G. Erkol, M. Oka, T. T. Takahashi, “Radiative transitions of doubly charmed baryons in lattice QCD,” Phy. Rev.
D 98, 114505 (2018).
H. Nagakura, S. Furusawa, H. Togashi, S. Richers, K. Sumiyoshi, S. Yamada, “Comparing treatments of weak reactions with nuclei insimulations of core-collapse supernovae,” Astrophys. J. Suppl. Ser. 240 (2019).
Y. Shimizu, Y. Yamaguchi, M. Harada, “Heavy quark spin multiplet structure of Pc -like pentaquark as P-wave hadronic molecular state,”
arXiv:1901.09215 [hep-ph] (2019).
J. Lee, N. Yamanaka, E. Hiyama, “Eﬀect of the Pauli exclusion principle in the electric dipole moment of 9 Be with |∆S | = 1 interactions,”
Phy. Rev. C 99, 055503 (2019).

[Proceedings]
Y. Yamaguchi, “Spin degeneracy of Hadronic molecules in the heavy quark region,” J. Phys. Conf. Ser. 981, 012015 (2018).

Oral Presentations[International Conference etc.]
E. Hiyama, “Structure of light p-shell Ξ hypernuclei,” The 13th International Conference on Hypernuclear and strange particle Physics,
Portsmouth, USA, June 2018.
E. Hiyama, “Recent progress of few-body problems in Physics,” International Conference on Simplicity, Symmetry and Beauty of Atomic
Nuclei, Shanghai, China, September 2018.
E. Hiyama, “Recent progress of hypernuclear physics,” 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Societyof Japan, Hawaii, USA, October 2018.
E. Hiyama, “Structure of light hypernuclei,” International workshop on Universal Physics In Many-Body Quantum Systems—From
Atoms to Quarks—, Tokai, Ibaraki, December 2018.
E. Hiyama, “Future Prospect In hypernuclear physics using HIAF,” International workshop on “HIAF High-Energy Beam Line Physics
and Nuclear Astrophysics,” Beijing, China, December 2018.
E. Hiyama, “Structure of light s-shell Ξ hypernuclei,” 57th International Winter meeting on Nuclear physics, Bormio, Italy, January 2019.
E. Hiyama, “Five-body structure of pentaquark,” Korea-Japan Joint Workshop on the Present and Future in Hadron Physics at J-PARC,
Busan, Korea March, 2019.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

H. Togashi, E. Hiyama, M. Takano, “Hyperon equation of state for core-collapse simulations based on the variational many-body theory,”
HYP2018, Norfolk, USA, June 2018.
H. Togashi, K. Nakazato, Y. Takehara, S. Yamamuro, H. Suzuki, M. Takano, “Supernova equation of state and symmetry energy at subnuclear densities,” 8th International Symposium on Nuclear Symmetry Energy (NuSYM2018), Busan, Korea, September 2018. (ট଴ߨԋ)
H. Togashi, “Systematic study of nuclear equations of state in core-collapse supernovae,” Deciphering Multi-dimensional Nature of Corecollapse Supernovae via Gravitational-wave and Neutrino Signatures (SNeGWν2018), Toyama, Japan, October 2018.
H. Togashi, “Systematic study of supernova equations of state at sub-nuclear densities with the Thomas-Fermi calculation,” 5th Joint
Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan, Hawaii, USA, October 2018.
H. Togashi, M. Takano, K. Nakazato, Y. Takehara, S. Yamamuro, H. Suzuki, K. Sumiyoshi, E. Hiyama, “Equation of state for hyperonic
nuclear matter and its application to compact astrophysical objects,” International workshop on “Hadron structure and interaction indense matter,” Tokai, Japan, November 2018. (ট଴ߨԋ)
Y. Yamaguchi, “πJ/ψ-DD̄∗ potential described by the quark exchange diagram,” XXII International Conference on Few-Body Problemsin Physics, Caen, France, July 2018.
Y. Yamaguchi, “πJ/ψ-DD̄∗ potential described by the quark exchange diagram,” The XXIVth International Baldin Seminar on HighEnergy Physics Problems, Dubna, Russia, September 2018.
Y. Yamaguchi, “Short range πJ/ψ-DD̄∗ potential by the constituent quark model,” Workshop on Dense Matter from Chiral Eﬀective
Theories 2018, Nagoya, Japan, October 2018.
Y. Yamaguchi, “Short range πJ/ψ-DD̄∗ interaction by the quark exchange diagram,” 5th Joint Meeting of the APS Division of Nuclear
Physics and the Physical Society of Japan, Hawaii, USA, October 2018.
Y. Yamaguchi, “Short range interaction in πJ/ψ-DD̄∗ channel,” The international workshop New aspects of the Hadron and Astro/Nuclear
Physics, The National University of Uzbekistan, Tashkent, Uzbekistan, November 2018.
Y. Yamaguchi, “Short range πJ/ψ-DD̄∗ potential,” International workshop on Hadron structure and interaction in dense matter, Tokai,
Ibaraki, November 2018.
Y. Yamaguchi, “Short-range meson-meson interaction in the hidden-charm sector,” International workshop: Clusters in quantum systems:
from atoms to nuclei and hadrons, Sendai, Japan, January, 2019.
K. U. Can, “Charmed baryon spectrum in 2+1-flavor Lattice QCD,” The 36th Annual International Symposium on Lattice Field Theory,
East Lansing, Michigan, USA, July 2018.
K. U. Can, “Charmed baryon spectrum in Lattice QCD—a work in progress,” XIIIth Quark Confinement and the Hadron Spectrum,
Maynooth University, Maynooth, Ireland, July–August 2018.
K. U. Can, “Spectrum of the charmed baryons in 2+1-flavor Lattice QCD,” The 8th International Conference on Quarks and Nuclear
Physics, Tsukuba, Japan, November 2018.

[Domestic Conference]
E. Hiyama, “Gaussian Expansion Method and itsapplication to nuclear physics,” RIKEN-YCU Joint Workshop, Wako, Japan, April 2018.
H. Togashi, “Microscopic equation of state for supernovae and compact stars,” RIKEN-YCU Joint Workshop, Wako, Japan, April 2018.
෋ֽำ, ංࢁӵඒࢠ, ୋ໺ਖ਼ར, ʮόϦΦϯؒ૬‫֩ͮ͘جʹ༻࡞ޓ‬෺࣭ͷঢ়ଶํఔࣜͱఱମ෺ཧ΁ͷԠ༻ʯ, ‫ڀݚ‬ձʮॏྗ೾‫؍‬ଌ࣌୅ͷ r ϓϩηεͱෆ҆ఆ֩ʯ, ࿨ޫࢢ, 2018 ೥ 6 ݄.
෋ֽำ, ʮ֩෺࣭ঢ়ଶํఔࣜͱߴີ౓ఱମ‫ݱ‬৅ʯ, ཧ‫۝—ݚ‬େϫʔΫγϣοϓ—ૉཻࢠɾ‫͔֩ࢠݪ‬ΒӉ஦΁—, ਆ‫ށ‬, 2018 ೥ 11 ݄.
(ট଴ϨϏϡʔߨԋ)
Y. Yamaguchi, “Heavy exotics near thresholds and Hadron interactions,” RIKEN-YCU Joint Workshop, Wako, Japan, April 2018ࢁ‫޺߁ޱ‬, ʮπJ/ψ-DD̄∗ νϟϯωϧʹ͓͚Δۙ‫ྗ཭ڑ‬ʯ, ཧ‫۝—ݚ‬େϫʔΫγϣοϓ —ૉཻࢠɾ‫͔֩ࢠݪ‬ΒӉ஦΁—, ਆ‫ࢢށ‬, 2018೥ 11 ݄.
ࢁ‫޺߁ޱ‬, ҆ഒ޾େ, ෱઒‫࣏ݡ‬, อࡔ३, ʮπJ/ψ-DD̄∗ νϟϯωϧʹ͓͚Δۙ‫཭ڑ‬૬‫༻࡞ޓ‬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ෱Ԭ,2019 ೥ 3 ݄.
K. U. Can, “Hadron physics in Lattice QCD,” RIKEN-YCU Joint Workshop, Wako, Japan, April 2018.
J. Lee, “Binding energy of Be-9-lambda,” RIKEN-YCU Joint Workshop, Wako, Japan, April 2018.

[Others]
H. Togashi, M. Takano, “Cluster variational method for hyperonic nuclear matter with coupled channels,” 8th International Conferenceon Quarks and Nuclear Physics (QNP2018), Tsukuba, Japan, November 2018.
H. Togashi, “Eﬀects of nuclear saturation properties on the supernova equations of state at sub-nuclear densities,” 2nd Annual Symposiumof GW-genesis, Kyoto, Japan, November 2018.

Awards෋ֽำ, ฏ੒ 30 ೥౓ཧԽֶ‫ࡩॴڀݚ‬෣৆‫ڀݚ‬঑ྭ৆, 2019 ೥ 3 ݄.
෋ֽำ, 2018 ೥౓‫ૅج‬Պֶɾࠃࡍಛผ‫ڀݚ‬һ‫ڀݚ‬੒Ռൃදձϙελʔ৆ʢ෺ཧֶ I ෼໺ʣ, 2019 ೥ 1 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 structure of
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 firstpolarized-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. RIKENBNL Research Center (RBRC) directed by S. Aronson carries our core team at BNL for those exciting researches using the PHENIX
detector. We have observed that the proton spin carried by gluons is finite and indeed sizable. We also identified W bosons in theelectron/positron decay channel and in the muon decay channel, with which we are about to conclude 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. We are also performing technical developments such as novel ion sources, fine-pitch silicon pixel detectors andhigh-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 release of charged pion double spin asymmetries in 2017 by PHENIX and are currently being prepared for
publication. The ordering of the three pion asymmetries allows a direct determination of the sign of the gluon polarization which has
been found to be nonzero. With the valence quark spin contribution already reasonably well known, the contributions from sea quarks
and orbital angular momenta remain to be understood. PHENIX has collected data to access the sea quark polarizations via leptonic
decays of W bosons. In 2018, the world’s only forward and backward W boson single spin asymmetries have been published, thus
completing the publication of all W related measurements of PHENIX.
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. The mechanism for such a behavior is not known and the publication ofthese results in 2018 has stimulated substantial theoretical discussions to understand these findings. 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 theoretical models describing the non-linear eﬀects of high gluon densities in nuclei suggested by the socalled 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 been submitted to publication for
positive hadrons and a more detailed publication is prepared including the negative hadrons.
In June of 2017, we installed an electro-magnetic calorimeter 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 preliminary results are currently being prepared for publication. Some of us are participating in the
Fermilab SeaQuest experiment as a pilot measurement of muon pairs from Drell-Yan process using 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 2019 to study the sea-quark orbit eﬀect of the polarized proton in 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 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 2018, transverse momentum
dependent cross sections of pions, kaons and protons were extracted 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.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(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 v2 and v3 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 (Phy. 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
is smaller than that of charm decay electrons for 3 < pT < 4 GeV/c. This is the first observation of bottom electron suppression inheavy ion collisions, and the first result that shows the bottom and charm suppression is diﬀerent. The results of b → e and c → emeasurement in the 2015 p + p run has been published in Phys. Rev. D 99, 092003 (2019). The centrality dependence of the
suppression b → e and c → e from the 2014 Au+Au data will be published soon. Preliminary results of the flow of b → e and c → e
was presented in Quark Matter 2018 conference.
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, 1 TB 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
GreatWave supercomputer system operated by the Advanced Center for Computing and Communication (ACCC). In addition, we
operate a dedicated server for the RHICf group and two servers for the J-PARC E16 group, to keep their dedicated compilation andlibrary 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 aredelivered, and their assembly processes have started. Read-out electronics and trigger logic modules were also fabricated and delivered.
Development of firmware on the trigger logic modules is on-going. We have been a member of the CERN-RD51 collaboration toacquire the read-out technology for GEM. The current MoU for RD51will be 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 will be completed in the first half of 2020 to perform
this experiment with the stage-2 approval. We are preparing the spectrometer toward the Run 0.
(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 “eRHIC.” The present PHENIX detector is repurposed to the sPHENIX (super PHENIX) detector
which reuses the Babar solenoid magnet at SLAC and is covered by the hadronic calorimeter which was not available in the previous
RHIC experiments. The sPHENIX project is now funded by DOE, and RIKEN will participate in the construction of the inner silicon
tracker (INTT). The R&D of the INTT has been in progress since 2015 and the 2nd generation prototype successfully demonstrated adesigned performance through the beam test executed at Fermilab in March 2018. The pre-production model including a full readout
chain will be completed after the examination in the 2nd round beam test at Fermilab in June 2019 followed by the final technicalreview in Summer, 2019.
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 eRHIC. We are preparing test bench to perform R&D for the forward hadron calorimeter.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Members
Group Director
Hideto EN’YO (Director, RNC)
Vice Chief Scientist
Yasuyuki AKIBA
Research/Technical Scientists
Yasushi WATANABE (Senior Research Scientist)
Satoshi YOKKAICHI (Senior Research Scientist)
Yuji GOTO (Senior Research Scientist)

Ralf SEIDL (Senior Research Scientist)
Itaru NAKAGAWA (Senior Research Scientist)

Postdoctoral Researcher
Koki KANNO
Research Associate
Wataru NAKAIInternational Program Associates
Minho KIM (Korea Univ.)

Junsang PARK (Seoul Nat’l Univ.)

Senior Visiting Scientists
Toshiaki SHIBATA (Tokyo Tech.)Takashi NAKANO (Osaka Univ.)

Visiting Scientists
Kyoichiro OZAWA (KEK)
Kenji FUKUSHIMA (Univ. of Tokyo)
Susumu SATO (JAEA)
Tomohiro NISHITANI (Nagoya Univ.)
Megumi NARUKI (Kyoto Univ.)
Tomonori TAKAHASHI (Osaka Univ.)
Kiyoshi TANIDA (JAEA)
Tsutomu MIBE (KEK)
Taku GUNJI (Univ. of Tokyo)
Masahiro OKAMURA (BNL)
Kazuya AOKI (KEK)

Shunzo KUMANO (KEK)
Munehisa OHTANI (Kyorin Univ.)
Bentz WOLFGANG (Tokai Univ.)
Kenichi NAKANO (Tokyo Tech.)Shin-ya SAWADA (KEK)Maya SHIMOMURA (Nara Women’s Univ.)
Kenta SHIGAKI (Hiroshima Univ.)
Hiroaki MENJO (Nagoya Univ.)
Sanghwa PARK (Stony Brook University)
Yuhei MORINO (KEK)
Tomoya HOSHINO (Yokogawa Electric Co.)

Student Trainees
Mana UENO (Nagoya Univ.)
Jaehee YOO (Korea University)
Qidong Zhou (Nagoya Univ.)
Yosuke UEDA (Hiroshima Univ.)
Seiya MIYATA (Univ. of Tokyo)
Kenta SATO (Nagoya Univ.)
Sakiko ASHIKAGA (Kyoto Univ.)
Hiromu ASO (Rikkyo Univ.)
Yuri ITO (Nara Woman’s Univ.)
Sakurako ISHIMARU (Nara Woman’s Univ.)
Tomoko SAKAMOTO (Nara Woman’s Univ.)
Kaede KAMANO (Nara Woman’s Univ.)

Risa NISHITANI (Nara Woman’s Univ.)
Kazuki SUZUKI (Kyoto Univ.)
Hiroki KATO (Tsukuba Univ.)
Ryohei FUJII (Kyoto Univ.)
Takahiro ICHINO (Rikkyo Univ.)
Yoko MINATO (Nara Woman’s Univ.)
Ayaka SUZUKI (Nara Woman’s Univ.)
Tomoki MURAKAMI (Univ. of Tokyo)
Se Young HAN (Ewha Womans Univ.)
Kazuya NAKAGAWA (Tsukuba Univ.)
Kazuki SATO (Tsukuba Univ.)

Interns
Minjung KIM (Seoul Nat’l Univ.)
Kenichiro SHIINA (Rikkyo Univ.)

Masaya ICHIKAWA (Kyoto Univ.)
Benard MULILO (Korea University)

Part-time Workers
Hidekazu MASUDA (Rikkyo Univ.)
Kazuya NAGASHIMA (Hiroshima Univ.)
Yorito YAMAGUCHI

Masato TSURUTA (Rikkyo Univ.)
Michiko SEKIMOTO- 367 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

AssistantKeiko SUZUKI

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
R. Arnaldi et al. (NA60 Collaboration), “Nuclear dependence of light neutral meson production in p-A collisions at 400 GeV with NA60,”
Eur. Phys. J. C 79, no.5, 443 (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,” Phy. Rev. D 99, no.9, 092003 (2019).
√
C. Aidala et al. (PHENIX Collaboration), “Nonperturbative transverse momentum broadening in dihadron angular correlations in sNN =200 GeV proton-nucleus collisions,” Phy. Rev. C 99, no.4, 044912 (2019).
A. Adare et al. (PHENIX Collaboration), “Pseudo rapidity dependence of particle production and elliptic flow in asymmetric nuclear√
collisions of p + Al, p + Au, d + Au, and 3 He + Au at sNN = 200 GeV,” Phys. Rev. Lett. 121, no.22, 222301 (2018).
√
C. Adare et al. (PHENIX Collaboration), “Low-momentum direct photon measurement in Cu + Cu collisions at sNN = 200 GeV,” Phy.
Rev. C 98, no.5, 054902 (2018).
A. Adare et al. (PHENIX Collaboration), “Creation of quark-gluon plasma droplets with three distinct geometries,” Nature Phys. 15,
no.3, 214–220 (2019).
C. √Aidala et al. (PHENIX Collaboration), “Measurements of µµ pairs from open heavy flavor and Drell-Yan in p + p collisions at
s = 200 GeV,” Phy. Rev. D 99, no.7, 072003 (2019).
C. Aidala et al. (PHENIX Collaboration), “Nonperturbativetransverse-momentum-dependent eﬀects in dihadron and direct photon√
hadron angular correlations in p + p collisions at s = 200 GeV,” Phy. Rev. D 98, no.7, 072004 (2018).
C. Aidala et al. (PHENIX Collaboration), “Single-spin asymmetry of J/ψ production in p + p, p + Al, and p + Au collisions with√transversely polarized proton beams at sNN = 200 GeV,” Phy. Rev. D 98, no.1, 012006 (2018).
A. Adare et al. (PHENIX Collaboration),“Cross section and longitudinal single-spin asymmetry AL for forward W± → µ ± ν production√in polarized p + p collisions at s = 510 GeV,” Phy. Rev. D 98, no.3, 032007 (2018).
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,” Phy. Rev. C 99, no.5, 054903 (2019).
A. Adare et al. (PHENIX Collaboration), “Measurement of emission angle anisotropy via long-range angular correlations with high pT√
hadrons in d + Au and p + p collisions at sNN = 200 GeV.” Phy. Rev. C 98, no.1, 014912 (2018).
A. Adare et al. (PHENIX Collaboration), “Measurements of mass-dependent azimuthal anisotropy in central p + Au, d + Au, and 3 He +√Au collisions at sNN = 200 GeV,” Phy. Rev. C 97, 064904 (2018).
√
A. Adare et al. (PHENIX Collaboration),“Measurement of ϕ-meson production at forward rapidity in p + p collisions at s = 510 GeV√
and its energy dependence from s = 200 GeV,” Phy. Rev. D 98, no.9, 092006 (2018).
C. Aidala et al. (PHENIX Collaboration), “Measurements of multiparticle correlations in d + Au collisions at 200, 62.4, 39, and 19.6 GeV
and p + Au collisions at 200 GeV and implications for collective behavior,” Phys. Rev. Lett. 120, no.6, 062302 (2018).
C. Aidala et al. (PHENIX Collaboration), “Nuclear dependence of the transverse-single-spin asymmetry for forward neutron production√in polarized p + A collisions at sNN = 200 GeV,” Phys. Rev. Lett. 120, no.2, 022001 (2018).
Y. Itow et al., “Recent results from the LHCf and RHICf experiments,” EPJ Web Conf. 208, 05004 (2019).

Oral Presentations[International Conference etc.]
I. Nakagawa, “Medium-energy nuclear physics at RHIC with sPHENIX and an sPHENIX forward upgrade,” XXVI International Workshop on Deep Inelastic Scattering and related Subjects, 17th , Kobe, Japan, April 2018.
Y. Goto, “Asymmetry measurement of very forward neutral particle production in the RHICf experiment,” Diﬀraction and Low-x 2018,
29th , Reggio Calabria, Italy (Invited), August 2018.
Y. Goto (RHICf collaboration), “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, “Nucleon structure study at RHIC and EIC,” YKIS2018b Symposium on Recent Developments in Quark-Hadron Sciences, 12th ,Kyoto, Japan (Invited), June 2018.
Y. Goto, “Electron-Ion Collider project,” Workshop on Progress on Hadron Structure Functions in 2018, 19th , Tsukuba, Japan (Invited),
November 2018.

[Domestic Conference]
S. Ichikawa, ʮJ-PARC E16 ࣮‫ݧ‬ͷͨΊͷτϦΨʔத‫ܧ‬ϞδϡʔϧͷϑΝʔϜ΢ΣΞ։ൃ‫ͼٴ‬ੑೳධՁʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ, ໺ా, 2018 ೥ 3 ݄ 22–25 ೔.
K. Suzuki, ʮJ-PARC E16 ࣮‫͚͓ʹݧ‬Δ Hadron Blind Detector ͷͨΊͷτϦΨʔճ࿏ͷ։ൃʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ, ໺
ా, 2018 ೥ 3 ݄ 22–25 ೔.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 KN interaction, and clarify the nature of kaon in nuclei. At Spring-8 and at GSI, we areplanning to study omega and eta’ nuclei. By these experiments, we aim to be a world-leading scientific research group using theselight meta-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 KN, the K 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 planned to identify the nature of the “K − pp” bound state by the in-flight 3 He(K − , n) reaction, whichallows us to investigate such state both in the formation via the missing-mass spectroscopy using the emitted neutron, and in its
decay via the invariant-mass spectroscopy by detecting decay particles from “K − pp.” For the experiment, we constructed a dedicatedspectrometer 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 themass threshold of M(K − pp) (total mass of kaon and two protons) at the lower momentum transfer q region. We conducted a successive
experiment to examine the nature of the observed kinematical anomaly in the Λpn final state, and we confirmed the existence of thebound state below the mass threshold of M(K − pp) at as deep as the binding energy of 50 MeV. The momentum transfer q naturally
prefers lower momentum for the bound state formation, but the observed event concentration extended as large as ∼650 MeV/c. The
simplest interpretation based on the PWIA calculation indicates that the observed object could be as small as ∼0.5 fm. This observationmeans that a meson (qq) 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 neverbeen observed before.
(1-2) Precision X-ray measurement of kaonic atom
To study the KN 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,- 369 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 → 1s transition of kaonic deuteron (K − -d). We have measured
same transition of kaonic hydrogen (K − -p), but the width and shift from electro-magnetic (EM) value reflect only isospin average ofthe Kbar N interaction. We can resolve isospin dependence of the strong interaction by the measurements both for K − -p and K − -d. The
experiment J-PARC E57 aims at pioneering measurement of the X-rays from K − -d atoms. Prior to full (stage-2) approval of 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.
(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) Novel superconducting state having the steeper nodal gaps in the quasi two-dimensional organic superconductor λ[BETS]2 GaCl4(2) Tiny magnetic moments and spin structures of Ir4+ in hole-doped pyrochlore iridates Y1.95−y Cu0.05 Cay Ir2 O7 andEu2−x Ca x Ir2 O7(3) Magnetism and spin structure in superoxide CsO2 , RbO2 and NaO2
(4) Magnetic properties of the nano-cluster gold in the border of macro- and micro-scale(5) Novel magnetic properties of nano-size La-based high-T c superconducting cuprates(6) Eﬀects of the spatial distributions of magnetic moments and muon positions estimated from density functional theory (DFT)and dipole-field calculations(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.
We had been working on the R&D of the “ultra-cold muon” generation based on the following technique, namely, positive muon
beam with thermal energy has been produced by laser ionization of muoniums in vacuum (bound system of µ+ and electron) emitted
from the hot tungsten surface by stopping “surface muon beam” at Port-3. However, the muon yield and obtained emittance was far
from satisfactory, and remained to be far from any kind of realistic application.
Therefore, in this mid-term, we are developing two key components, high eﬃciency muonium generator at room temperatureand high intensity ionization laser. The study of muonium generator has been done in collaboration with TRIUMF. In 2013, wedemonstrated 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 2017 with more than 20 aerogel target having diﬀerent surface conditions. We are analyzing thedata to identify which condition most contributed to increasing the muonium emission eﬃciency. We also developed a high power
Lyman-α laser in collaboration with laser group 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. While we plan to increase the intensity by one more order,
we are suﬀering from optical inhomogeneity in making a larger size crystal so far. We are developing several schemes to solve this- 370 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)problem.
Concerning the muonic atom, we are planning a new precise measurement of proton radius. A large discrepancy was found recently 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. Preparation of the hydrogen target,
mid-infrared laser and muon spin polarization detectors is in progress. As a key parameter for designing the experiment, we need thequench rate of the muonic proton polarization due to collision with surrounding protons, for which only theoretical estimations areavailable. We successfully measured the quench rate of muonic deuterium polarization in deuterium gas, which confirmed the long
lifetime consistent with the calculation. Measurement for muonic proton is planned in FY2019.

Members
Group Director
Masahiko IWASAKI
Research/Technical Scientists
Haruhiko OUTA (Senior Research Scientist)
Fuminori SAKUMA (Senior Research Scientist)
Isao WATANABE (Senior Research Scientist)

Yue MA (Senior Research Scientist)
Kenta ITAHASHI (Senior Research Scientist)

Contract Researcher
Katsuhiko ISHIDA
Research Consultants
Yoshinori AKAISHI
Masayasu KAMIMURA

Hironari MIYAZAWA
Eiichi YAGI

Junior Research Associates
Fahmi ASTUTI (Hokkaido Univ.)
Muhamad UMAR (Hokkaido Univ.)

Juila ANGEL (Hokkaido Univ.)

International Program Associates
Harison Binti ROZAK (UTM)
Redo Muhammad RAMADHAN (Universitas Indonesia)

Suci WINARSIH (Universitas Indonesia)
Utami WIDYAISWARI (Universitas Indonesia)

Senior Visiting Scientist
Kazuhiro TANAKA (KEK)
Visiting Scientists
Toshimitsu YAMAZAKI (Univ. of Tokyo)
Atsushi OKAZAWA (Univ. of Tokyo)
Mototsugu MIHARA (Osaka Univ.)
Hiroko ARIGA (Hokkaido Univ.)
Donald George FLEMING (Univ. of British Columbia)
Yoshiki TANAKA(GSI)
Yasuo NOZUE (Osaka Univ.)
Katsuhiko NISHIMURA (Univ. of Toyama)
Takehito NAKANO (Osaka Univ.)
Kenji MATSUDA (Univ. of Toyama)
Tadashi ADACHI (Sophia Univ.)
Mohamed Ismail MOHAMED IBRAHIM (USM)
Zyun Francis EZAWA (Tohoku Univ.)
Shukri SULAIMAN (USM)
Yasuyuki ISHII (Shibaura Inst. of Tech.)
Eberhard WIDMANN (SMI)
Johann ZMESKAL (SMI)
Koichi ICHIMURA (Hokkaido Univ.)
Risdiana (UNPAD)
Youichi IGARASHI (KEK)
Takao SUZUKI (Shibaura Inst. of Tech.)
KwangYong CHOI (Chung-Ang Univ.)
Georg Peter BERG (Univ. of Notre Dame)
Emma HAETTNER (GSI)

Takayuki GOTO (Sophia Univ.)
Andrea VACCHI (INFN)
Masaya ENOMOTO (Tokyo Univ. of Sci.)
Dita PUSPITA SARI (Shibaura Inst. of Tech.)
Hiroyuki FUJIOKA (Tokyo Tech.)Retno ASIH (Institut Teknologi Sepuluh Nopember)
Takayuki KAWAMATA (Tohoku Univ.)
Lee SEUNGWON (Univ. of Toyama)
Agustinus NUGROHO (ITB)
Takahiro NAMIKI (Univ. of Toyama)
Yuta SADA (Osaka Univ.)
Hiraki KO-ICHI (Fukushima Medical Univ.)
Ichiro SHIRAKI (Univ. of Yamanashi)
Naohito SAITO (KEK)
Kensuke SUZUKI (Tohoku Univ.)
Kouichirou SHIMOMURA (KEK)
Kyosuke ISODA (Kagawa Univ.)
Ryousuke KADONO (KEK)
Ken SUZUKI (SMI)
Wataru HIGEMOTO (JAEA)
Catalina Oana CURCEANU(INFN)
Yoji KOIKE (Tohoku Univ.)
Maryam HASSANVAND(IUT)
Kazuhiko SATOH (Saitama Univ.)- 371 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Kazuki UENO (KEK)
Masaru YOSOI (Osaka Univ.)
Lusy SAFRIANI (UNPAD)
Kazuki OHISHI (Comprehensive Res. Org. for Sci. and Soc.)
Hiroyuki NOUMI (Osaka Univ.)
Yasuhiro MIYAKE (KEK)

Zhuan XU (Zhejiang Univ.)
Yu OISHI (KEK)
Hiroshi TANIDA (Toyama Prefectural Univ.)
Seiko KAWAMURA(JAEA)
Satoru HIRENZAKI (Nara women’s Univ.)

Research Fellow
Yuki NOZAWA (Osaka Univ.)
Student Trainees
Yuni WATANABE (Univ. of Tokyo)
Sungwon YOON (Catholic Univ. of Korea)
Ryo KITAMURA (Univ. of Tokyo)
Akane SAKAUE (Kyoto Univ.)

Kazuki MATSUI (Sophia Univ.)
Muhamad UMAR (Hokkaido Univ.)
Ainul Fauzeeha Binti ROZLAN (Univ. Saints Malaysia)
Irwan RAMLI (Hokkaido Univ.)

Part-time Worker
Irwan RAMLI (Research Part-time Worker I)
Assistants
Mitsue YAMAMOTO
Yoko FUJITA

Noriko ASAKAWA

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
Darminto, R. Asih, Kurniasari, M. A. Baqia, S. Mustofa, Suasmoro, T. Kawamata, K. Kato, I. Watanabe, Y. Koike, “Enhanced magnetism by temperature induced defects in reduced graphene oxide prepared from coconut shells,” IEEE Transactions on Magnetics 54,
1600105-1–5 (2018).
W. Liao et al., “Measurement and mechanism investigation of negative and positive muon-induced upsets in 65-nm bulk SRAMS,” IEEE
Trans. Nucl. Sci. 65 (2018) 1734. *E. Mocchiutti et al., (FAMU collaboration), “First FAMU observation of muon transfer from mup atoms to higher-Z elements,” Journalof Instrumentation 13, 02019 (2018). *A. Adamczak et al., (FAMU collaboration), “The FAMU experiment at RIKEN-RAL to study the muon transfer rate from hydrogen toother gases,” Journal of Instrumentation 13, 12033 (2018). *Y. Sassa, M. Mansson, O. K. Forslund, O. Tjernberg, V. Pomjakushin, O. Ofer, E. J. Ansaldo, J. H. Brewer, I. Umegaki, Y. Higuchi,
Y. Ikedo, H. Nozaki, M. Harada, I. Watanabe, H. Sakurai, J. Sugiyama, “The metallic quasi-1D spin-density-wave compound NaV2 O4
studied by angle-resolved photoelectron spectroscopy,” J. Electron. Spectrosc. Relat. Phenom. 224, 79–83 (2018).
R. Asih, N. Adam, S. S. Mohd-Tajudin, D. P. Sari. K. Matsuhira, H. Guo, M. Wakeshima, Y. Hinatsu, T. Nakano, Y. Nozue. S. Slaiman,
M. I. Mohamed-Ibrahim, P. K. Biswas, I. Watanabe, “Magnetic moments and ordered states in pyrocholore irridates Nd2 Ir2 O7 andSm2 Ir2 O7 studies by muon-spin relaxation,” J. Phys. Soc. Jpn. 86, 240705 (2018).
M. Miyajima, F. Astuti, T. Kakuto, A. Matsuo, D. P. Sari, R. Asih, K. Okunishi, T. Nakano, Y. Nozue, K. Kindo, I. Watanabe, T. Kambe,“Magnetism and high-magnetic field magnetization in alkali superoxide CsO2 ,” J. Phys. Soc. Jpn. 87, 063704-1–4 (2018).
T. Suzuki, K. Katayama, I. Kawasaki, I. Watanabe, H. Tanaka, “Spin fluctuations in the spin-1/2 kagome lattice antiferromagnet(Rb1−x Cs x )2 Cu3 SnF12 around the quantum critical point detected by muon-spin relaxation technique,” J. Phys. Soc. Jpn. 87, 074708-1–6(2018).
T. Kawamata, K. Ohashi, T. Takamatsu, T. Adachi, M. Kato, I. Watanabe, Y. Koike, “Impurity eﬀects on the electronic state in theunderdoped (Cu-free) superconductor T′ -La1.8 Eu0.2 CuO4 studied by muon spin relaxation,” J. Phys. Soc. Jpn. 87, 094717 (2018).
S. N. A. Afmad, S. Sulaiman, L. S. Ang, I. Watanabe, “First-principle studies on magnetic structure and exchange interactions of βEtn Me4−n Z[Pd(dmit)2 ]2 ,” J. Phys. Soc. Jpn. 87, 124709-1–6 (2018).
F. Astuti, M. Miyajima. T. Fukuda. M. Kodani, T. Nakano, T. Kambe, I. Watanabe, “Anionomagnetiam combined lattice symmetry inalkali-metal superoxide RbO2 ,” J. Phys. Soc. Jpn. 88, 043701 (2018).
K. L. Brown, C. P. J. Stockdale, H. Luo, X. Zhao, J.-H. Li, D. Viehland, G. Xu, P. M. Gehring, K. Ishida, A. D. Hillier, C. Stock, “Depth
dependent element analysis of PbMg1/3 Nb2/3 O3 using muonic X-rays,” Journal of Physics: Condensed Matter 30, 125703 (2018). *Kumar, C. N. Cuo, F. Astuti, T. Shang, M. K. Lee, C. S. Lue, I. Watanabe, J. A. T. Baker, T. Shiroka, L. J. Chang, “Nodeless superconductivity in the cage-type superconductor Sc5 Ru6 Sn18 with preserved time-reversal symmetry,” J. Phys. Condens. Matt. 30, 315803-1–11(2018).
E. Mocchiutti et al., (FAMU collaboration), “FAMU: study of the energy dependent transfer rate Λµp to µO,” J. Phys. C 1138, 2018. *E. Spurayoga, A. A. Nugroho, D. Onggo, A. O. Polyakov, T. T. M. Palstra, I. Watanabe, “3D long-range magnetic ordering in(C2 H5 NH3 )2 CuCl4 compound revealed by internal magnetic field from muon spin rotation and first principal calculation,” Physica
B 545, 76–79 (2018).

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M. Clemenza et al., “CHNET TANDEM experiment: Use of negative muons at RIKEN-RAL Port 4 for elemental characterization of
Nuragic votive ship samples,” Nucl. Instrum. Methods Phys. Res. A, https://doi.org/10.1016/j.nima.2018.11.076 . *S. Bae et al., “First muon acceleration using a radio frequency accelerator,” Phys. Rev. Accel. Beams 21, 050101 (2018). *η-PRiME/Super-FRS Collaboration (Y. K. Tanaka (Tokyo U.) et al.), “Missing-mass spectroscopy of the 12 C(p, d) reaction near the η’meson production threshold,” Phys. Rev. C 97, 015202 (2018), DOI: 10.1103/PhysRevC.97.015202
J-PARC E15 collaboration (S. Ajimura (Osaka U) et al.), “K-ppiAF Collaboration (T. Nishi (Tokyo U. & Nishina Ctr., RIKEN) et al.),“Spectroscopy of pionic atoms in 122 Sn(d, 3 He) reaction and angular dependence of the formation cross sections,” Phys. Rev. Lett. 120,152505 (2018), DOI: 10.1103/PhysRevLett.120.152505
K. Kurashima, T. Adachi, Kensuke M. Suzuki, Y. Fukunaga, T. Kawamata, T. Noji, H. Miyasaka, I. Watanabe, M. Miyazaki, A. Koda,
R. Kadono, Y. Koike,” “Development of ferromagnetic fluctuations in heavily overdoped (Bi, Pd)2 Sr2 CuO6+δ coper oxides,” Phys. Rev.
Lett. 121, 057002-1–6 (2018).
J-PARC E15 collaboration (S. Ajimura (Osaka U) et al.), “K − pp, a K-meson nuclear bound state, observed in 3 He(K − , Λp)n reactions,”
Phys. Lett. B 789, 620–625 (2019). *piAF Collaboration (T. Nishi et al.), “Spectroscopy of pionic atoms in 122 Sn(d, 3 He) reaction and angular dependence of the formation
cross sections,” Phys. Rev. Lett. 120, 152505 (2018), DOI: 10.1103/PhysRevLett.120.152505.

[Proceedings](Original Papers) *Subject to Peer Review
P. Strasser et al., “New precise measurements of muonium hyperfine structure at J-PARC MUSE,” EPJ Web Conf. 198 (2019) 00003(8 pages), https://doi.org/10.1051/epjconf/201919800003, Proc. of Quantum Technology International Conference 2018
(QTech 2018)
B. V. Hampshire, K. Butcher, K. Ishida, G. Green, D. Paul, A. Hillier, “Using negative muons as a probe for depth profiling silver Roman
coinage,” Heritage 2, 400–407 (2019), Proc. of the 8th International Conference on Synchrotron Radiation and Neutrons in Art andArchaeology, doi:10.3390/heritage2010028. *T. Sumura, T. Ishimoto, H. Kuwahara, K. Kurashima, Y. Koike, I. Watanabe, M. Yiyazaki, A. Koda, R. Kadono, T. Adachi, “Reductioneﬀects on Cu-spin fluctuation in the electron-doped T ′ -cuprate Pr1.3−x La0.7 Ce x CuO4+δ (x = 0.10),” JPS Conf. Proc. 21, 011027 (2018).
A. Hillier, K. Ishida, P. Seller, M. C. Veale, M. D. Wilson, “Element specific imaging using muonic x-rays,” JPS Conf. Proc. 21, 011042(2018)
Risdiana, T. Saragi, W. A. Somantri, S. Pratiwi, D. Suhendar, M. Manawan, B. J. Suroto, I. Watanabe, “Zn-induced development of the
Cu-spin correlation in electron-doped superconducting cuprates of Eu2−x Ce x CuO4 ,” J. Phys. Conf. Ser. 1013, 012180-1–5 (2018).
S. Kanda, K. Ishida, M. Iwasaki, Y. Ma, S. Okada, A. Takamine, H. Ueno, K. Midorikawa, N. Saito, S. Wada, M. Yumoto, Y. Oishi,
M. Sato, S. Aikawa, K. S. Tanaka, Y. Matsuda, “Measurement of the proton Zemach radius from the hyperfine splitting in muonichydrogen atom,” J. Phys. Conf. Ser. 1138, 012008 (2018). 10th Int. Conf. on Precision Physics of Simple Atomic Systems.
A. D. Hillier, J. S. Lord, K. Ishida, C. Rogers, “Muons at ISIS,” Philosophical Transactions Royal Society A 377, 20180064 Contribution
to a Theo Murphy meeting issue “Cosmic-ray muography”
S. Kanda, K. Ishida, M. Iwasaki, Y. Ma, A. Takamine, H. Ueno, K. Midorikawa, N. Saito, S. Wada, M. Yumoto, S. Okada, Y. Oishi,
M. Sato, S. Aikawa, K. S. Tanaka, Y. Matsuda, “Precision laser spectroscopy of the ground state hyperfine splitting in muonic hydrogen,” Proceeding of Science (NuFact2017) 122.

Oral Presentations[International Conference etc.]
S. Kanda, “Precision spectroscopy of muonic systems with high-intensity pulsed muon beam,” Workshop on Lepton Flavor Physics with
Most Intense DC Muon Beams, Tokyo, April 2018.
S. Kanda, “Measurement of the proton Zemach radius from the hyperfine splitting in muonic hydrogen atom,” PSAS2018, Vienna, May
2018.
F. Sakuma, “Search for the kaonic bound state KNN at J-PARC,” 15th International Workshop on Meson Physics (MESON2018),
KRAKOW, POLAND, June 7–12, 2018.
F. Sakuma, “Search for the Kaonic Bound State KNN via 3 He(K − , Λp/pΣπ)n reactions,” YKIS2018b Symposium, “Recent developments
in quark-hadron sciences,” Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan, June 11–15, 2018.
K. Ishida, “Future opportunities in µ-p atoms,” FAMU Meeting, Trieste, Italy, June 2018.
M. Iwasaki, “A quest for the “K − pp” bound state via 3 He(K − , n) reaction, J-PARC E15 experiment,” The 13th International Conference
on Hypernuclear and Strange Particle Physics (HYP2018), Portsmouth, June 24–29, 2018.
H. Asano, “Spectroscopic study of the Λ(1405) resonance via the d(K − , n) reaction at J-PARC,” The 13th International Conference onHypernuclear and Strange Particle Physics (HYP2018), Portsmouth, June 24–29, 2018.
H. Asano, “Spectroscopic study of the Λ(1405) resonance via the d(K − , n) reaction at J-PARC,” The 13th International Conference onHypernuclear and Strange Particle Physics, Virginia, USA, June 2018.
T. Yamaga, “Studies of the KNN bound state via the exclusive analysis of the in-flight (K − , n) reaction at J-PARC,” The 22nd International
Conference on Few-Body Problems in Physics (FB22), Caen, France, July 9–13, 2018.
S. Kanda, “Laser spectroscopy of the hyperfine splitting in muonic hydrogen atom by a measurement of decay electron asymmetry,”
Nucleon Spin Structure at Low Q: A Hyperfine View, Trento, July 2018.
S. Kanda, “Precision spectroscopy of exotic atoms involving muon,” NuFact2018, Virginia, August 2018.

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H. Asano, “High-rate fiber tracker,” Workshop on Physics with General Purpose Spectrometer in the High-momentum Beam Line, Osaka,
Japan, August 2018.
S. Kanda, “Laser spectroscopy of the ground-state hyperfine splitting in muonic hydrogen atom,” Symposium for Muon and Neutrino
Physics 2018, Osaka, September 2018.
H. Noumi, “πΣ spectra in the kaon-induced reaction on deuteron,” The fifth joint meeting of the Division of Nuclear Physics of theAmerican Physical Society with the nuclear physicists of the Physical Society of Japan, Waikoloa, USA, October 2018.
K. Ishida, “Proton Zemach radius measurement by the hyperfine splitting of muonic hydrogen“(invited),” The fifth Joint Meeting of the
Nuclear Physics Divisions of the American Physical Society and the Physical Society of Japan, Waikoloa, USA, October 2018.
S. Okada, “Kaonic atom X-ray spectroscopy with transition edge sensors,” The 2018 Applied Superconductivity Conference (ASC2018),
Seattle, USA, October 28–November 2, 2018.
T. Yamaga, “Results of KNN search via the (K − , n) reaction at J-PARC,” The 8th International Conference on Quarks and Nuclear Physics(QNP2018), Tsukuba, Japan, November 13–17, 2018.
S. Kawasaki, “The E31 spectroscopic experiment of Λ(1405) via in-flight d(K − , n) reaction at J-PARC K1.8BR,” The 8th International
Conference on Quarks and Nuclear Physics (QNP2018), Tsukuba, Japan, November 13–17, 2018.
F. Sakuma, “K-nuclear bound state at J-PARC,” 13th International Conference on Nucleus-Nucleus Collisions (NN2018), Omiya, Saitama,
Japan, December 4–8, 2018.
T. Hashimoto, “Kaonic atom experiments at J-PARC,” The 8th International Conference on Quarks and Nuclear Physics (QNP2018),
Tsukuba, Japan, November 13–17, 2018.
T. Yamaga, “Results of experimental search for KNN bound state at J-PARC,” Reimei Workshop on Experimental and Theoretical Hadron
Physics: Recent Exciting Developments, Tokai, Japan, January 9–11, 2019.
H. Asano, “Λ(1405) from d(K − , n) reaction,” Reimei Workshop on Experimental and Theoretical Hadron Physics: Recent Exciting
Developments, Tokai, Japan, January 9–11, 2019.
S. Okada, “Kaonic atom x-ray spectroscopy at J-PARC,” Reimei Workshop on Experimental and Theoretical Hadron Physics: Recent
Exciting Developments, Tokai, Japan, January 9–11, 2019.
K. Ishida, “Proton radius measurement with muonic atoms,” International Workshop on the Structure of the Proton, Sagae, Yamagata,February 2019.
S. Kanda, “Development of instruments for the proton radius measurement at RIKEN,” International Workshop on the Structure of theProton, Sagae, Yamagata, February 2019.
K. Itahashi, “Spectroscopy of pionic atoms and deduction of chiral symmetry in nuclear matter,” NN2018, Omiya, Saitama, December
2018.
K. Itahashi, “Spectroscopy of meson-nucleus bound states,” HIAF Workshop, Beijing, November 2018.

[Domestic Conference]ੴాউ඙, ʮϛϡΦϯ‫ʹࢠݪ‬ΑΔཅࢠ൒‫ܾܘ‬ఆʯ, େࡕେֶཧֶ෦෺ཧηϛφʔ, ๛த, 2018 ೥ 8 ݄.
ࠤ‫࢙ؒٱ‬య, ʮNew results on the “K − pp” bound state from J-PARC ‫֩ࢠݪ‬தʹ͓͚Δϋυϩϯͷੑ࣭ͱΧΠϥϧରশੑͷ໾ׂʯ,౦๺େֶిࢠޫཧֶ‫ڀݚ‬ηϯλʔ, ઋ୆, 2018 ೥ 9 ݄.
‫ڮ‬ຊ௚, ʮJ-PARC ʹ͓͚Δ K தؒࢠ‫ ࢠݪ‬X ઢ෼ޫʯ, ‫֩ࢠݪ‬தʹ͓͚Δϋυϩϯͷੑ࣭ͱΧΠϥϧରশੑͷ໾ׂ, ౦๺େֶిࢠޫ
ཧֶ‫ڀݚ‬ηϯλʔ, ઋ୆, 2018 ೥ 9 ݄.
ਆా૱ଠ࿠, “Residual polarization and hyperfine transition rate in muonic hydrogen,” ৽ֶज़ྖҬ‫ڀݚ‬ʮӉ஦‫؍‬ଌ‫ݕ‬ग़‫ࢠྔͱث‬ϏʔϜͷग़ձ͍. ৽ͨͳԠ༻΁ͷՍ͚‫ڮ‬ʯ, ΩοΫΦϑγϯϙδ΢Ϝ, ౦๺, 2018 ೥ 12 ݄.
ਆా૱ଠ࿠, “Laser spectroscopy of the hyperfine splitting in muonic hydrogen,” ୈ 9 ճ Muon ՊֶͱՃ଎‫ڀݚڀݚث‬ձ, େࡕ, 2019
೥ 1 ݄.
ੴాউ඙, ʮཧ‫ ݚ‬RAL ϛϡΦϯࢪઃʯ, ୈ 9 ճʮMuon ՊֶͱՃ଎‫ڀݚث‬ʯ, RCNP, ਧా, 2019 ೥ 1 ݄.
ੴాউ඙, ʮϛϡΦϯਫૉ‫ʹࢠݪ‬ΑΔ༝ࢤ൒‫ܘ‬ଌఆʯ, ELPH ‫ڀݚ‬ձ C021ʮిࢠࢄཚʹΑΔ‫—ڀݚ֩ࢠݪ‬ཅࢠ൒‫ܘ‬, ෆ҆ఆ֩ͷిՙີ౓෼෍Λத৺ʹ—ʯ, ౦๺େֶిࢠޫཧֶ‫ڀݚ‬ηϯλʔ, ઋ୆, 2019 ೥ 3 ݄.
ઙ໺लޫ, ʮJ-PARC E31 ࣮‫͚͓ʹݧ‬Δ Λ(1405) ੜ੒ͷӡಈྔҠߦґଘੑʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019
೥ 3 ݄.
O. Zhadyra, “The physics experiment E31 to search for the Λ(1405) via the d(K − , n)πΣ reaction at J-PARC K1.8BR,” ೔ຊ෺ཧֶձୈ
74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
ઙ໺लޫ, ʮJ-PARC E31PARC E31 ࣮‫͚͓ʹݧ‬Δ Λ(1405) ੜ੒ͷӡಈྔҠߦੑʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ,2019 ೥ 3 ݄.
઒㟒৽‫ޗ‬, ʮd(K − , n)π0 Σ0 ൓ԠʹΑΔ Λ(1405) ͷ‫ڀݚ‬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄.
ਆా૱ଠ࿠, ʮϛϡʔΦϯਫૉ‫ࢠݪ‬ͷϨʔβʔ෼ޫʹ޲͚ͨεϐϯճస࣮‫ݧ‬ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019
೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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, and Lattice
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 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, particularly the operation and technical support for the RBRC 400 Teraflop QCDCQ (QCD
Chiral Quark) lattice gauge theory computer. 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 (concurrent: Director, Nishina Center for
Accelerator-Based Science)
Administrative Staﬀ
Kazushige FUKUSHIMA (Administration Manager, Nishina
Center and iTHEMS Promotion Oﬃce)
Pamela ESPOSITO (Administrative Assistant)- 375 -

Maureen MCNEIL-SHEA (Administrative Assistant)
Hiroshi ITO (Deputy Administration Manager, Nishina Centerand iTHEMS Promotion Oﬃce)

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 identified the possibility for the higher-order phase transitions in QCD(H. Nishimura, R. Pisarski, V. Skokov) by using the novel approach based on the matrix models.
The first-principle studies of QCD phase diagram at finite baryon density using the lattice Monte Carlo approach are very diﬃcult
because of the so-called “sign problem.” The work by H. Nishimura and Y. Tanizaki, in collaboration with J. Verbaarschot of Stony
Brook Nuclear Theory group, has proposed a new kind of the gradient flow method that can be used to alleviate this problem.
An important feature of strongly interacting matter at finite baryon density is the liquid-gas phase transition. The paper by
H. Nishimura (in collaboration with M. Ogilvie and K. Pangeni) develops a field-theoretic approach to the liquid-gas phase transition
based on an eﬀective 3D field theory.
Quantum anomalies play an important role in QCD phase transitions. Y. Tanizaki, Y. Kikuchi (who will join the RBRC Theory
group in 2018) and collaborators utilized the method of “anomaly matching” to obtain important constraints on the dynamics ofdeconfinement and chiral restoration phase transitions in QCD. They also used this method to study the vacuum structure of QCD at
finite theta-angle.
(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, V. Skokov (in collaboration with A. Kovner, and others) 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 thatthe correlations inside the small x distributions eﬀectively generate odd azimuthal harmonics in hadron distributions, with a long-range
separation in rapidity. In collaboration with A. Kovner and M. Lublinsky, V. Skokov also investigated the possible eﬀect of quarkgluon correlations at small x on the studies of the Chiral Magnetic Eﬀect in pA collisions at RHIC. D. Kharzeev, in collaboration with
W. Li and Z. Tu, investigated the role of fluctuating proton size on the CME studies in pA collisions, and found that these fluctuations
induce a significant correlation between the direction of magnetic field and the reaction plane, enabling the observation of CME.
The Isobar run at RHIC (made possible due to the RIKEN scientists working on Zr source) completed in 2018 will establish
or rule out the existence of the Chiral Magnetic Eﬀect (originally proposed by RBRC theorists) in the quark-gluon plasma. During
the past year, D. Kharzeev and H.-U. Yee, in collaboration with Y. Hirono, M. Mace and others have developed the Chiral MagnetoHydrodynamics (CMHD) approach to the Chiral Magnetic Eﬀect (CME) in quark-gluon plasma. The first numerical results of CMHD
have become available due to the collaboration of RBRC with the ECHO-QGP group. H.-U. Yee and collaborators investigateddynamical instabilities in CMHD. D. Kharzeev and H.-U. Yee, in collaboration with M. Stephanov, solved a long-standing puzzle of
the apparent discrepancy between the field theory and the kinetic theory on the magnitude of the CME current at finite frequency.
D. Kharzeev, with Y. Hirono and A. Sadofyev, proposed a new “chiral propulsion eﬀect” for the chiral solitons on vortices in chiralmedia.
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.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(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
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, Y. Tanizaki and Y. Kikuchi (a postdoc who has joined RBRC in 2018), in collaboration with R. Meyer, foundthat asymmetric Weyl semimetals support a giant photocurrent as a result of chiral anomaly. D. Kharzeev, Y. Kikuchi and R. Meyer
also proposed a new kind of dynamical CME in asymmetric Weyl semimetals that does not require an external source of chirality, andproposed an experiment to test their prediction. D. Kharzeev with his Stony Brook student S. Kaushik have identified a new type ofquantum oscillations in the CME conductivity at finite doping, and with another student E. Philip have established the existence of thechiral magnetic photocurrent.
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 KHARZEEVSpecial Postdoctoral Researchers
Yuya TANIZAKI

Hiromichi NISHIMURARBRC Researchers
Yuta KIKUCHI (Postdoctoral Researcher)Jordy DE VRIES (RHIC Physics Fellow)

Chun SHEN (RHIC Physics Fellow)
Vladimir SKOKOV (RHIC Physics Fellow)- 377 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 arewell 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. 52 (2019)(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 are

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 the shaded 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).

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.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

primarily 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 in heavy ion physics at RHIC is now to investigate the properties of the matter. RBRC have played theleading roles in some of the most important results from PHENIX in the study of the matter properties. These include (1) measurementsof heavy quark production from the single electrons from heavy flavor decay (2) measurements of J/ψ production (3) measurementsof di-electron continuum and (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
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.

Fig. 4. Preliminary results of the elliptic flow strength v2 of single electrons from charm and bottom decays.

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.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (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 each of the2014 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 v2 of b → e and c → e has been presented in Quark Matter 2018 conference.
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 AKIBA (Deputy Chief Scientist)
RBRC Researchers
Jan BERNAUER (RHIC Physics Fellow)
Itaru NAKAGAWA (RIKEN Spin Program Researcher, concurrent: Radiation Lab.)
Takashi HACHIYA (RIKEN BNL Fellow, Nara Women’s University)
Takashi ICHIHARA (RIKEN Spin Program Researcher, concurrent: RI Physics Lab.)
Yorito YAMAGUCHI
Takahito TODOROKIAtsushi TAKETANI (RIKEN Spin Program Researcher, concurrent: Neutron Beam Technology Team, Advanced Photonics Technology Development Group, RAP)
Visiting Scientists
Stefan BATHE (Baruch College University of New York)
Takao SAKAGUCHI (BNL)
Rachid NOUICER (BNL)
Takashi SAKO (University of Tokyo)

Megan CONNORS (RHIC Physics Fellow)
Marta VERWEIJ (RHIC Physics Fellow)
Yasushi WATANABE (RIKEN Spin Program Researcher, concurrent: Radiation Lab.)
Satoshi YOKKAICHI (RIKEN Spin Program Researcher, concurrent: Radiation Lab.)
Yuji GOTO (RIKEN Spin Program Researcher, concurrent:
Radiation Lab.)
Ralf SEIDL (RIKEN Spin Program Researcher, concurrent:
Radiation Lab.)

Masahiro OKAMURA (BNL)
Hiroaki MENJO (Nagoya University)
Gaku MITSUKA (KEK)

List of Publications & Presentations
Publications
Oral Presentations[International Conference etc.]√
T. Hachiya, “Nuclear modification factor and flow of charm and bottom quarks in Au + Au collisions at sNN = 200 GeV by the PHENIX
Experiment,” Quark Matter 2018 (QM2018), Venice, Italy, May 13–19, 2018.
T. Hachiya, “Heavy Flavor Physics at RHIC,” :Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS(HAWAII2018), Waikoloa, HI, USA, October 23–27, 2018.
T. Hachiya, “Recent experimental studies on high-energy heavy ion collisions,” 13th International Conference on Nucleus-Nucleus Collisions (NN2018), Omiya, Japan, December 4–8, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 future Electron Ion Collider (EIC), Hyper Kamiokande,
DUNE, or the origin of the current matter rich universe (rather than anti-matter). Some of members carry out interesting researchon strong gauge dynamics other than QCD to get hints for the true nature of the Higgs particle or the Dark Matter, or even quantum
gravity.

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- 382 -

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Fig. 1. Muon g − 2 Hadronic Light-by-Ligh contribution. HLbL diagram (left). New sampling method (red) reduce the statistical noise from the previous
method (black) by more than a factor of 10 at the same cost.

Fig. 2. Physical-point extrapolation for gA (left), Summary of LQCD calculations (right) from Nature 558, 91–94 (2018).

CKM theory for kaons and B mesons that include the new calculation of b-baryon decay, Λb → p; the electromagnetic propertiesof 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 lifetime of the neutron is determined by its axial charge, gA, which also governs pion exchange between nucleons. Memberof RBRC (Rinaldi) and collaborators (including C. C. Chang of iTHEMS) carried out 1%-level accurate LQCD calculation of gA for
the first time by employing several innovative methods (such as unconventional extraction of the QCD matrix element using FeynmanHellmann theorem, diﬀerent sea- and valence quark actions, or the computational use of Graphic Processor Units). The paper was
published in the Nature journal, was covered by many press releases, and also led to the Gordon Bell Prize finalist.
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.

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Table 1. Summery of current physics program and their impacts.

Members
Group Leader
Taku IZUBUCHI
Special Postdoctoral Researchers
Akio TOMIYA

Enrico RINALDIRBRC Researchers
Yasumichi AOKI (RIKEN BNL Fellow, KEK)
Ethan NEIL (RHIC Physics Fellow)
Stefan MEINEL (RHIC Physics Fellow)

Sergey SYRITSYN (RHIC Physics Fellow)
Luchang JIN (RHIC Physics Fellow)

Visiting Scientists
Thomas BLUM (Univ. of Connecticut)
Chulwoo JUNG (BNL)
Shigemi OHTA (KEK)
Tomomi ISHIKAWA (Shanghai Jiao-Tong Univ.)
Christoph LEHNER (BNL)

Meifeng LIN (BNL)
Robert MAWHINNEY (Columbia Univ.)
Hiroshi OKI (Nara Women’s Univ.)
Christopher KELLY (Columbia Univ.)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
E. Rinaldi, S. Syritsyn, M. L. Wagman, M. I. Buchoﬀ, C. Schroeder, J. Wasem, “Lattice QCD determination of neutron-antineutron matrix
elements with physical quark masses,” arxiv:1901.07519, submitted to Phys. Rev. D. *A. Nicholson, E. Berkowitz, H. Monge-Camacho, D. Brantley, N. Garron, C. C. Chang, E. Rinaldi, C. Monahan, C. Bouchard,
M. A. Clark, B. Joo, T. Kurth, B. Tiburzi, P. Vranas, A. Walker-Loud, “Symmetries and interactions from lattice QCD,”
arxiv:1812.11127. *E. Berkowitz, M. A. Clark, A. Gambhir, K. McElvain, A. Nicholson, E. Rinaldi, P. Vranas, A. Walker-Loud, C. C. Chang, B. Joo, T. Kurth,
K. Orginos, “Simulating the weak death of the neutron in a femtoscale universe with near-Exascale computing,” arxiv:1810.01609,
Gordon Bell prize finalist *E. Rinaldi, S. Syritsyn, M. L. Wagman, M. I. Buchoﬀ, C. Schroeder, J. Wase, “Neutron-antineutron oscillations from lattice QCD,”
arxiv:1809.00246. *- 384 -

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T. Appelquist, R. C. Brower, G. T. Fleming, A. Gasbarro, A. Hasenfratz, X. -Y. Jin, E. T. Neil, J. C. Osborn, C. Rebbi, E. Rinaldi,
D. Schaich, P. Vranas, E. Weinberg, O. Witzel, “Nonperturbative investigations of SU(3) gauge theory with eight dynamical flavors,”
Phys. Rev. D 99, 014509 (2019). *C. Alexandrou, L. Leskovec, S. Meinel, J. Negele, S. Paul, M. Petschlies, A. Pochinsky, G. Rendon, S. Syritsyn, “πγ → ππ transition andthe ρ radiative decay width from lattice QCD,” Phys. Rev. D 98, 7, 074502 (2018). *T. Izubuchi, Y. Kuramashi, C. Lehner, E. Shintani (PACS collaboration), “Finite-volume correction on the hadronic vacuum polarization
contribution to muon g − 2 in lattice QCD,” Phys. Rev. D 98, 054505 (2018). *P. Petreczky, T. Izubuchi, L. Jin, C. Kallidonis, N. Karthik, S. Mukherjee, C. Shugert, S. Syritsyn, “Pion structure from lattice QCD,”
arXiv:1812.04334 *T. Blum, P. A. Boyle, V. Gülpers, T. Izubuchi, L. Jin, C. Jung, A. Jüttner, C. Lehner, A. Portelli, J. T. Tsang (RBC and UKQCD
Collaborations), “Calculation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment,” Phys. Rev.
Lett. 121, 022003 (2018). * [Editors’ suggestion]
C. C. Chang, A. Nicholson, E. Rinaldi, E. Berkowitz, N. Garron, D. Brantley, H. Monge-Camacho, C. Monahan, C. Bouchard,
M. A. Clark, B. Joo, T. Kurth, K. Orginos, P. Vranas, A. Walker-Loud, “A per-cent-level determination of the nucleon axial couplingfrom quantum chromodynamics,” Nature 558, 91–94 (2018). *T. Izubuchi, X. Ji, L. Jin, I. W. Stewart, Y. Zhao, “Factorization theorem relating Euclidean and light-cone parton distributions,” Phys.
Rev. D 98, 056004 (2018). *T. Appelquist, R. C. Brower, G. T. Fleming, A. Gasbarro, A. Hasenfratz, J. Ingoldby, J. Kiskis, J. C. Osborn, C. Rebbi, E. Rinaldi,
D. Schaich, P. Vranas, E. Weinberg, O. Witzel, “Linear sigma EFT for nearly conformal gauge theories,” Phys. Rev. D 98, 114510(2018). * [Editors’ suggestion]
P. Boyle, R. Hudspith, T. Izubuchi, A. Jüttner, C. Lehner, R. Lewis, K. Maltman, H. Ohki, A. Portelli, M. Spraggs (RBC and UKQCD
Collaborations), “Novel |Vus | determination using inclusive strange τ decay and lattice hadronic vacuum polarization functions,” Phys.
Rev. Lett. 121, 202003 (2018). *A. Carosso, A. Hasenfratz, E. T. Neil, “Nonperturbative renormalization of operators in near-conformal systems using gradient flows,”
Phys. Rev. Lett. 121, 201601 (2018). *K. Hashimoto, S. Sugishita, A. Tanaka, A. Tomiya, “Deep learning and holographic QCD,” Phys. Rev. D 98, 106014 (2018). *L. Jin, H-W. Lin et al., “Proton isovector helicity distribution on the lattice at physical pion mass,” Phys. Rev. Lett. 121, 24, 242003(2018). *X. Feng, L. -C. Jin, X. -Y. Tuo, S. -C. Xia, “Light-neutrino exchange and long-distance contributions to 0 ν 2 β decays: An exploratory
study on ππ → ee,” Phys. Rev. Lett. 122, 022001 (2019). *A. Nicholson, E. Rinaldi et al., “Heavy physics contributions to neutrinoless double beta decay from QCD,” Phys. Rev. Lett. 121, 172501(2018). *B. Chakraborty, E. Neil et al., “Strong-isospin-breaking correction to the muon anomalous magnetic moment from lattice QCD at thephysical point,” Phys. Rev. Lett. 120, 152001 (2018). *V. Ayyar, T. DeGrand, M. Golterman, D. C. Hackett, W. I. Jay, E. T. Neil, Y. Shamir, B. Svetitsky, “Spectroscopy of SU(4) composite
Higgs theory with two distinct fermion representations,” Phys. Rev. D 97, 074505 (2018). *A. Bazavov, E. Neil et al., “Short-distance matrix elements for D0 -meson mixing for N f = 2 + 1 lattice QCD,” Phys. Rev. D 97, 034513(2018). *S. Meinel, “Λc → N form factors from lattice QCD and phenomenology of Λc → nℓ+ νℓ and Λc → pu+ µ− decays,” Phys. Rev. D 97,
034511 (2018). *N. Hasan, J. Green, S. Meinel, M. Engelhardt, S. Krieg, J. Negele, A. Pochinsky, S. Syritsyn, “Computing the nucleon charge and axial
radii directly at Q2 = 0 in lattice QCD,” Phys. Rev. D 97, 034504 (2018). *E. Rinaldi, E. Berkowitz, M. Hanada, J. Maltz, P. Vranas, “Toward holographic reconstruction of bulk geometry from lattice simulations,”
J. High Energy Phys. 1802, 042 (2018). *J. -W. Chen, L. Jin, H. -W. Lin, Y. -S. Liu, Y. -B. Yang, J. -H. Zhang, Y. Zhao, “Lattice calculation of parton distribution function fromLaMET at physical pion mass with large nucleon momentum,” Phys. Rev. Lett. 121, 242003 (2018). *J. -W. Chen, L. Jin et al., “Kaon distribution amplitude from lattice QCD and the flavor SU(3) symmetry,” Nucl. Phys. B 939, 429–446(2019). *J. -W. Chen, T. Ishikawa, L. Jin, H. -W. Lin, A. Schäfer, Y. -B. Yang, J. -H. Zhang, Y. Zhao, “Gaussian-weighted parton quasi-distribution,”
Sci. China Phys. Mech. Astron. 62, 991021 (2019).
J. -W. Chen, T. Ishikawa, L. Jin, H. -W. Lin, Y. -B. Yang, J. -H. Zhang, Y. Zhao, “Parton distribution function with nonperturbative
renormalization from lattice QCD,” Phys. Rev. D 97, 014505 (2018). *K. Hashimoto, S. Sugishita, A. Tanaka, A. Tomiya, “Deep learning and holographic QCD,” Phys. Rev. D 98, 106014 (2018).
K. Kashiwa, Y. Kikuchi, A. Tomiya, “Phase transition encoded in neural network,” arXiv:1812.01522. *[Proceedings](Original Papers) *Subject to Peer Review
USQCD Collaboration (V. Cirigliano, T. Izubuchi, S. Syritsyn et al.,), “The role of lattice QCD in searches for violations of fundamental
symmetries and signals for new physics,” arXiv:1904.09704 [hep-lat].
K. Maltman, T. Izubuchi, H. Ohki et al., “Current status of inclusive hadronic τ determinations of |Vus |,” SciPost Phys. Proc. 1, 006 (2019).

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S. Syritsyn, T. Izubuchi, H. Ohki, “Calculation of nucleon electric dipole moments induced by quark chromo-electric dipole moments and
the QCD θ-term,” arXiv:1901.05455 [hep-lat].
J. -S. Yoo, Y. Aoki, T. Izubuchi, S. Syritsyn, “Proton decay matrix element on the lattice with physical pion mass,” PoS LATTICE2018,
187, (2019).
M. Bruno, T. Izubuchi, C. Lehner, A. Meyer, “On isospin breaking in τ decays for (g − 2)µ from lattice QCD,” Proc. Sci. LATTICE2018,
135 (2018).
S. Syritsyn, T. Izubuchi, H. Ohki, “Progress in the nucleon electric dipole moment calculations in lattice QCD,” arXiv:1810.03721.
P. Boyle, R. J. Hudspith, T. Izubuchi, A. Jüttner, C. Lehner, R. Lewis, K. Maltman, H. Ohki, A. Portelli, M. Spraggs, “|Vus | determinationfrom inclusive strange tau decay and lattice HVP,” EPJ Web Conf. 175, 13011 (2018).
S. Hashimoto, B. Colquhoun, T. Izubuchi, T. Kaneko, H. Ohki, “Inclusive B decay calculations with analytic continuation,” EPJ Web
Conf. 175, 13006 (2018).
M. Abramczyk, S. Aoki, T. Blum, T. Izubuchi, H. Ohki, S. Syritsyn, “Computing nucleon EDM on a lattice,” EPJ Web Conf. 175, 06027(2018).
T. Izubuchi, Y. Kuramashi, C. Lehner, E. Shintani, “Lattice study of finite volume eﬀect in HVP for muon g − 2,” EPJ Web Conf. 175,
06020 (2018).
S. Syritsyn, “Nucleon EDM on a lattice at the physical point,” LATTICE 2018, July 22–28, 2018; to be published in Proc. Sci. Confinement.
M. Engelhardt, J. Green, N. Hasan, S. Krieg, S. Meinel, J. Negele, J. Negele, A. Pochinsky, S. Syritsyn, “Quark orbital angular momentum
in the proton evaluated using a direct derivative method,” Proc. Sci. SPIN2018, 047 (2019).
S. Paul, G. Silvi, C. Alexandrou, G. Koutsou, S. Krieg, L. Leskovec, S. Meinel, J. Negele, M. Petschlies, A. Pochinsky, G. Rendon,
S. Syritsyn, “Towards the P-wave nucleon-pion scattering amplitude in the Delta(1232). channel,” Proc. Sci. LATTICE2018, 089(2018).
G. Rendon, L. Leskovec, S. Meinel, J. Negele, S. Paul, M. Petschlies, A. Pochinsky, G. Silvi, S. Syritsyn, “Kπ scattering and the K ∗(892)resonance in 2 + 1 flavor QCD,” Proc. Sci. LATTICE2018, 073 (2018).
L. Leskovec, C. Alexandrou, S. Meinel, J. W. Negele, S. Paul, M. Petschlies, A. Pochinsky, G. Rendon, S. Syritsyn, “Calculating the ρradiative decay width with lattice QCD,” Proc. Sci. LATTICE2018, 065 (2018).
C. Kallidonis, S. Syritsyn, M. Engelhardt, J. Green, S. Meinel, J. Negele, A. Pochinsky, “Nucleon electromagnetic form factors at highQ2 from Wilson-clover fermions,” Proc. Sci. LATTICE2018, 125 (2018).
L. Leskovec, C. Alexandrou, S. Meinel, J. W. Negele, S. Paul, M. Petschlies, A. Pochinsky, G. Rendon, S. Syritsyn, “A lattice QCD studyof the ρ resonance,” CIPANP 2018, (2018).
S. Paul, C. Alexandrou, L. Leskovec, S. Meinel, J. Negele, M. Petschlies, A. Pochinsky, G. Rendon, S. Syritsyn, “ππ P-wave resonant
scattering from lattice QCD,” EPJ Web Conf. 175, 05022 (2018).
K Suzuki, S. Aoki, Y. Aoki, G. Cossu, H. Fukaya, S. Hashimoto (JLQCD Collaboration), “Axial U(1) symmetry at high temperature in
2-flavor lattice QCD,” EPJ Web of Conferences 175, 07025-1–8 (2018).
S. Aoki, Y. Aoki, G. Cossu, H. Fukaya, S. Hashimoto, K. Suzuki, “Topological susceptibility in Nf = 2 QCD at finite temperature,” EPJ
Web of Conferences 175, 07024-1–8 (2018).
C. Rohrhofer, Y. Aoki, G. Cossu, H. Fukaya, L. Ya. Glozman, S. Hashimoto, C. B. Lang, S. Prelovsek, “Degeneracy of vector-channel
spatial correlators in high temperature QCD,” EPJ Web of Conferences 175, 07029-1–8 (2018).
Y. Aoki, T. Aoyama, E. Bennett, M. Kurachi, T. Maskawa, K. Miura, K. Nagai, H. Ohki, E. Rinaldi, A. Shibata, K. Yamawaki, T. Yamazaki, “Flavor-singlet spectrum in multi-flavor QCD,” EPJ Web Conf. 175, 01008 (2018).
E. Berkowitz, A. Nicholson, C. C. Chang, E. Rinaldi, M. A. Clark, B. Joo, T. Kurth, P. Vranas, A. Walker-Loud, “Calm multi-baryon
operators,” EPJ Web Conf. 175, 08023 (2018).
E. Rinaldi, E. Berkowitz, M. Hanada, J. Maltz, P. Vranas, “Toward holographic reconstruction of bulk geometry from lattice simulations,”
EPJ Web Conf. 175, 05029 (2018).

Oral Presentations[International Conference etc.]
T. Izubuchi (invited), “Hadronic contributions to muon g − 2,” Frontiers in Lattice QCD and related topics, Kyoto Univ. Yukawa Institute,
April 15–26, 2019.
T. Izubuchi, “Lattice QCD studies of muon g − 2 and tau decay,” 6th KEK Flavor Factory Workshop (KEK-FF 2019), KEK, February 16,
2019.
T. Izubuchi, “Precise calculation of muon g − 2 based on lattice QCD,” Massively parallel programming from Quantum Chemistry andPhysics 2019, Kobe, RIKEN AICS, January 16, 2019.
T. Izubuchi (invited seminar), “|Vus | from τ,” Columbia University, January 28, 2019.
T. Izubuchi, “|Vus| from taus (LQCD),” invited talk, 10th International Workshop on the CKM Unitarity Triangle CKM2018, September
17–21, 2018.
T. Izubuchi (invited seminar), “Hadronic contributions to muon g − 2 —LQCD confronting the most precise experiments—,” Departmentof Theoretical Physics (DTP), Tata Institute of Fundamental Research (TIFR), Mumbai, India, April 26, 2018.
T. Izubuchi, “Nuclear form factor calculation using DWQCD,” 36th International Symposium on Lattice Field Theory (Lattice 2018), at
Lansing, MI, July 23–28, 2018.

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S. Meinel (invited), “B → K ∗ ℓℓ from lattice QCD,” 6th KEK Flavor Factory Workshop, Tsukuba, Japan, February 15, 2019.
S. Meinel (Invited parallel talk), “Exclusive semileptonic b baryon decays from lattice QCD,” 10th International Workshop on the CKM
Unitarity Triangle (CKM 2018), University of Heidelberg, Germany, September 18, 2018.
S. Meinel (Invited), “Form factors for b hadron decays from lattice QCD,” Frontiers in Lattice Quantum Field Theory, IFT, Madrid, Spain,
May 28, 2018.
S. Meinel, “Flavor physics with charm and bottom baryons, Invited seminar,” Cosmology Seminar, Arizona State University, Tempe, AZ,
May 2, 2018.
S. Meinel (invited), “Opportunities for lattice QCD in quark and lepton flavor physics,” USQCD All Hands Meeting, Fermilab, Batavia,
IL, April 20, 2018.
S. Meinel (invited), “Λb → Λ(∗)
c form factors from lattice QCD,” Challenges in Semileptonic B Decays, MITP, Mainz, Germany, April 9,
2018.
S. Syritsyn, “Nucleon electric dipole moments from Lattice QCD,” Theory Seminar, University of Maryland, October 11, 2018.
S. Syritsyn (invited), “Progress on the nucleon EDM in lattice QCD,” XIIIth Quark Confinement and Hadron Spectrum, Maynooth
University, Ireland, July 31–August 6, 2018.
Y. Aoki, “QCD phase transition,” (invited), International Workshop on Massively Parallel Programming for Quantum Chemistry andPhysics 2019, Kobe, Japan, January 15, 2019.
Y. Aoki (invited), “Topology and axial U(1) symmetry in two-flavor hot QCD, lattice and functional techniques for exploration of phasestructure and transport properties in quantum chromodynamics,” Dubna, Russia, September 5, 2018.
Y. Aoki, “Topological susceptibility in Nf = 2 QCD at finite temperature—volume study,” Lattice 2018, East Lancing, MI, USA, July 24,
2018.
Y. Aoki (invited), “Lattice QCD and hadron structure,” DIS 2018, Kobe, Japan, April 16, 2018.
L. Jin (plenary), The 36th Annual International Symposium on Lattice Field Theory (LATTICE 2018), July 2018.
L. Jin (invited), Second Plenary Workshop of the Muon g − 2 Theory Initiative, Mainz, June 2018.
L. Jin (invited), First Workshop of the Muon g − 2 Theory Initiative, Q Center, June 2017.
L. Jin (invited), QCD Evolution 2017, Jeﬀerson Lab, May 2017.
L. Jin (invited), Lattice PDF Workshop, University of Maryland, April 2018.
E. Neil, “Non-perturbative renormalization in Monte Carlo simulations using gradient flow,” CTQM Seminar, University of Colorado,
Boulder, CO. February 2019.
E. Neil, “Light composite scalar from Nf = 8 lattice gauge theory,” Continuum and Lattice Approaches to the Infrared Behavior of
Conformal and Quasi-Conformal Gauge Theories, Simons Center for Geometry and Physics, Stony Brook, NY, January 2018.
E. Rinaldi (invited seminar), “The neutron lifetime with near-Exascale computing,” Computational Science Initiative, BNL, Upton, NY,
January 2019.
E. Rinaldi (invited seminar), “First- principles lattice QCD calculations of the neutron beta decay: challenges and prospects,” Institut für
Kernphysik, Forschungzentrum, Jülich, Germany, December 2018.
E. Rinaldi (invited), “First-principles lattice QCD calculations of the neutron beta decay: challenges and prospects,” Particle Physics with
Neutrons at ESS, Nordita University, Stockholm, Sweden, December 2018.
E. Rinaldi (invited), “Lattice calculations for neutron-antineutron oscillations,” Particle Physics with Neutrons at ESS, Nordita University,
Stockholm, Sweden, December 2018.
E. Rinaldi (invited seminar), “Illuminating dark matter with supercomputers,” York University, Toronto, Canada, November 2018.
E. Rinaldi (invited), “First-principles QCD calculation of the neutron lifetime,” Beta Decay as a Probe of New Physics, the Amherst
Center for Fundamental Interactions, University of Massachusetts, Amherst, MA, November 2018.
E. Rinaldi (invited seminar), “New results on strongly-coupled theories near the conformal window,” University of Rome 3, Rome, Italy,
October 2018.
E. Rinaldi (invited seminar), “Beyond the Standard Model physics with lattice simulations,” University of Milan Bicocca, Milan, Italy,
October 2018.
E. Rinaldi (invited), “Lattice composite dark matter,” Interdisciplinary approach to QCD-like composite dark matter, ECT*, Trento, Italy,
October 2018.
E. Rinaldi, “Ungauging the gauge/gravity duality,” Quantum Gravity meets Lattice QFT, ECT*, Trento, Italy, September 2018.
E. Rinaldi, “Neutron-antineutron oscillations,” Lattice 2018, Michigan State University, USA, July 2018.
E. Rinaldi, “First-principles lattice QCD calculation of the neutron lifetime,” ICHEP2018, Seoul, South Korea, July 2018.
E. Rinaldi (invited seminar), “New results on strongly-coupled theories near the conformal window,” Tsukuba University, Tsukuba, Japan,
June, 2018.
E. Rinaldi, “Composite Dark Matter,” CIPANP18, Palm Springs, CA, USA, June, 2018.
E. Rinaldi (invited seminar), “How to test the gauge/gravity duality with lattice simulations,” New York University, New York, NY, USA,May 2018.
E. Rinaldi (invited), “High-precision tests of the gauge/gravity duality and future applications,” Lattice for Beyond the Standard Model
Physics (LBSM18), University of Colorado, Boulder, CO, USA, April 2018.
T. Akio, “Towards reduction of autocorrelation in HMC by machine learning,” Bielefeld university, October 2018.
T. Akio, “Detection of phase transition via convolutional neural networks,” Regenceburg university, October 2018.

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T. Akio, “Chiral phase transition of three flavor QCD with nonzero magnetic field using standard HISQ,” Eötvös Loránd University,
October 2018.
T. Akio, “Chiral phase transition of three flavor QCD with nonzero magnetic field using standard HISQ,” Oskaka University, November
2018.
T. Akio, “Chiral phase transition of three flavor QCD with nonzero magnetic field using standard HISQ,” Tsukuba University, November
2018.

[Domestic Conference]੨໦อಓ, ʮQCD ૬సҠ—‫ݱ‬ঢ়ͱղ໌ʹ޲͚ͯʯ, ૉཻࢠɾ‫֩ࢠݪ‬ɾӉ஦ʮ‫͔ژ‬Βϙετ‫͚ͯ޲ ʹژ‬ʯ, γϯϙδ΢Ϝ 2018, ஜ೾େֶ౦‫ژ‬Ωϟϯύε, ౦‫ژ‬, 2019 ೥ 1 ݄ 9 ೔.
੨໦อಓ, ʮQCD ͷ༗‫ݶ‬Թ౓૬సҠͱτϙϩδʔ—αϒ՝୊ AʮQCD ૬సҠʯ—ʯ, ॏ఺՝୊ 9 ‫ڀݚ‬ใࠂձ, ஜ೾େֶ CCS, ҵ৓,2018 ೥ 10 ݄ 3 ೔.
੨໦อಓ, ʮ2 ϑϨʔόʔ֨ࢠ QCD ͷߴԹ૬ʹ͓͚ΔσΟϥοΫεϖΫτϧͱ࣠ੑ U(1) ରশ ੑʯ, ೔ຊ෺ཧֶձ 2018 ೥ळ‫ظ‬େձ, ৴भେֶ, ௕໺, 2018 ೥ 9 ݄ 16 ೔.
੨໦อಓ, ʮ༗‫ݶ‬Թ౓ 2 ϑϨʔόʔ QCD ͷτϙϩδΧϧ‫ײ‬ड཰—༗‫ݶ‬ମੵޮՌʯ, ೔ຊ෺ཧֶձ 2018 ೥ळ‫ظ‬େձ, ৴भେֶ, ௕໺,2018 ೥ 9 ݄ 16 ೔.
੨໦อಓ, ʮ༗‫ݶ‬Թ౓ QCDɿ૬సҠ, τϙϩδʕ, axionʯ, YITPPPP2018,ʢট଴ߨԋʣ, ‫౎ژ‬େֶ, ‫౎ژ‬, 2018 ೥ 8 ݄ 9 ೔.
੨໦อಓ, “Topology and axial U(1) symmetry at hight temperature in Nf = 2 QCD,” ηϛφʔ, ཧ‫ ݚ‬AICS, ฌ‫ݿ‬, 2018 ೥ 1 ݄ 15 ೔.

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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.
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 theµSR 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 2016 to 2019, following subjects of material sciences are most importantachievements at the RIKEN-RAL muon facility:(1) Novel superconducting state having the steeper nodal gaps in the quasi two-dimensional organic superconductor λ[BETS]2 GaCl4(2) Tiny magnetic moments and spin structures of Ir4+ in hole-doped pyrochlore iridates Y1.95−y Cu0.05 Cay Ir2 O7 andEu2−x Ca x Ir2 O7(3) Magnetism and spin structure in superoxide CsO2 , RbO2 and NaO2
(4) Magnetic properties of the nano-cluster gold in the border of macro- and micro-scale(5) Novel magnetic properties of nano-size La-based high-T c superconducting cuprates(6) Eﬀects of the spatial distributions of magnetic moments and muon positions estimated from density functional theory (DFT)and dipole-field calculations(7) Measurement of Li and Na ion diﬀusion in battery materials(8) Muon as a probe of hydrogen behavior in functional and energy materials(9) Negative muon SR application to internal field measurement
Result-(1) We developed a novel method to determine the superconducting gap structure in conjunction with the density functional
theory calculations. It was concluded that the two-dimensional organic superconductor λ-[BETS]2 GaCl4 has a steeper superconducting
gap and clear line nodes showing both the s-wave and d-wave characters. Result-(2) Doped hole eﬀects on the magnetic properties ofcorner-shared magnetic moments on pyrochlore systems gave us new interpretations to understand exotic phenomena, like the quantum
criticality of magnetic moments and a quasi-magnetic monopole state. Result-(3) In CsO2 , we confirmed a novel coexisting state of
the so-called spin-liquid state and a magnetically ordered state of magnetic moment which are on the π-orbital of oxygen atoms.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

We also observed the spin-gap state in NaO2 . Those findings open a new scheme of quantum magnetic properties of π electrons onlight elements. Result-(4) and (5) The nano-size eﬀect show a new scheme of electronic properties of metallic element. The gold
is the most typical example to have a possibility to possess magnetic properties due to the nano-size eﬀect. We confirmed that thenano-gold cluster can have free electronic moment on one nano-cluster. The same nano-size eﬀect was tested on the La-based high-T csuperconducting oxide. The severe restriction on the magnetic interaction is expected to provide novel eﬀects on the magnetic andsuperconducting properties of the high-T c superconducting oxide. We confirmed the reduction in the magnetic interaction and thedisappearance of the superconducting state .by decreasing the size of the particle size. Result-(6) 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. Result-(7) Movement of ionsis an essential requirement for an eﬃcient battery. The µSR has been actively used to measure the ion hopping rate in microscopic
level in Li- and Na-ion batteries. We also started a study of macroscopic Li movement from its depth dependent concentration using
negative muons. Result-(8) Muon shows similar behavior as hydrogen in materials and its behavior can be measured even at very low
concentration. Thus µSR was applied to understand energy and functional materials such as graphene, TiO2 catalyst and hydrogenstorage materials. Result-(9) Recently a clear Kubo-Toyabe-type relaxation was observed for negative muons captured by Mg. This
will open the door to studying the dynamic behavior of light elements in solids with µ− SR from a fixed viewpoint of the nucleus.
We have been developing muon activities in Asian countries. We enhanced international collaborations to organize new µSR
experimental groups and to develop muon-site calculation groups using computational method. We renewed MOU with Universiti
Sains Malaysia (USM) in order to develop activities on the muon-site calculation. We are also continuing collaborations in µSR
experiments on strongly correlated systems with researchers from Taiwan and Korea including graduate students. We are starting
to collaborate 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), Bronze Agetools 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.
(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. Since there has been no appropriate probe to
study magnetism at surface and interface, the ultra-cold muon beam will open a new area of these research fields. In addition, thedevelopment of ultra-cold muon beam is very important as the source of ultra-cold (pencil-like small emittance) muon beam for muong − 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 andthe 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, and we are working hard
to improve the crystal.
We also succeeded in developing an eﬃcient muonium generator, laser ablated silica aerogel, which emits more muoniums
into vacuum even at room temperature. In 2013 at TRIUMF, by utilizing positron tracking method of muon decay position, we
demonstrated at least 10 times increase of the muonium emission eﬃciency by fabricating fine laser drill-holes on the surface ofsilica aerogel. Further study was carried out in 2017 to find the optimum fabrication that will maximize the muonium emission. An
alternative detection method using muonium spin rotation, which will be sensitive even to muoniums near the surface, was tested at
RIKEN-RAL in 2018 and was found successful.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 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 their experimental precision.
In contrast to the conventional measurement by means of electron, the PSI experiment utilized muonic hydrogen atom, and measured
two diﬀerent allowed transitions from one of the 2S levels to one of the 2P levels. The muonic atom has larger sensitivity to theproton radius because the negative muon orbits closer to the proton, although there is no reason why these measurements can yieldinconsistent results if there exists no exotic physics or unidentified phenomenon behind. The cause of the discrepancy is not understoodyet, thus a new measurement with independent method is much anticipated.
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. The study of the beam originatedbackground level gives us reasonably small level, in which we can conduct a precision measurement. Another key is the lifetime ofthe polarized triplet muonic hydrogen state. We successfully observed the muon spin precession of muonic deuterium atom in 2018
for the first time in the world, from which we can set limit on the lifetime. The measurement with muonic protium is planned 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 pass to ISIS, a refurbishment programme of the facility will be undertaken, a user programme
for Japanese scientists will continue, and the partnership between RIKEN and ISIS will be continued. The RIKEN-RAL collaborationis regularly highlighted as a good example of UK-Japanese science partnership at the UK-Japan Joint Committee on Science andTechnology (chaired by the UK Chief Scientific Advisor to Government and a counterpart from Japan) — for example, Dr. Kingand Dr. Watanabe presented RIKEN-RAL at the November 2016 meeting of the Committee. The RIKEN-RAL collaboration has
also enabled the development of collaborative activity between RIKEN and other Asian universities, e.g. through several MoUs withIndonesian and Malaysian universities.

Members
Director
Philip KING
Research Scientist
Isao WATANABE (concurrent: Meson Science Lab.)
Contract Researcher
Katsuhiko ISHIDA (concurrent: Meson Science Lab.)
Administration Manager
Kazushige FUKUSHIMA (concurrent: Nishina Center and
iTHEMS Promotion Oﬃce)

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
Q. Awan, J. Ahmad, Q. Sun, W. Hub, A. Berlie, Y. Liu, “Structure, dielectric and ferroelectric properties of lead-free(Ba, Ca)(Ti, Zr)O3−x BiErO3 piezoelectric ceramics,” Ceram. Int. 44, 6872–6877 (2018).
Darminto, R. Asih, Kurniasari, M. A. Baqia, S. Mustofa, Suasmoro, T. Kawamata, K. Kato, I. Watanabe, Y. Koike, “Enhanced magnetism by temperature induced defects in reduced graphene oxide prepared from coconut shells,” IEEE Transactions on Magnetics 54,
1600105-1–5 (2018).

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

W. Liao et al., “Measurement and mechanism investigation of negative and positive muon-induced upsets in 65-nm bulk SRAMS,” IEEE
Trans. Nucl. Sci 65 (2018) 1734. *R. Bethany. McBride, J. Lieschke, A. Berlie, D. L. Cortie, H. Y. Playford, T. Lu, N. Narayanan, R. L. Withers, D. Yu, Y. Liu, “Study of
the B-site ion behaviour in the multiferroic perovskite bismuth iron chromium oxide,” J. App. Phys. 123, 154104 (2018).
E. Mocchiutti et al. (FAMU collaboration), “First FAMU observation of muon transfer from mup atoms to higher-Z elements,” J. Instrum.
13, 02019 (2018). *A. Adamczak et al. (FAMU collaboration), “The FAMU experiment at RIKEN-RAL to study the muon transfer rate from hydrogen toother gases,” J. Instrum. 13, 12033 (2018). *Y. Sassa, M. Mansson, O. K. Forslund, O. Tjernberg, V. Pomjakushin, O. Ofer, E. J. Ansaldo, J. H. Brewer, I. Umegaki, Y. Higuchi,
Y. Ikedo, H. Nozaki, M. Harada, I. Watanabe, H. Sakurai, J. Sugiyama, “The metallic quasi-1D spin-density-wave compound NaV2 O4
studied by angle-resolved photoelectron spectroscopy,” J. Electron Spectrosc. Relat. Phenom. 224, 79–83 (2018).
R. Asih, N. Adam, S. S. Mohd-Tajudin, D. P. Sari. K. Matsuhira, H. Guo, M. Wakeshima, Y. Hnatsu, T. Nakano, Y. Nozue. S. Slaiman,
M. I. Mohamed-Ibrahim, P. K. Biswas, I. Watanabe, “Magnetic moments and ordered states in pyrocholore irridates Nd2 Ir2 O7 andSm2 Ir2 O7 studies by muon-spin relaxation,” J. Phys. Soc. Jpn. 86, 240705 (2018).
M. Miyajima, F. Astuti, T. Kakuto, A. Matsuo, D. P. Sari, R. Asih, K. Okunishi, T. Nakano, Y. Nozue, K. Kindo, I. Watanabe, T. Kambe,“Magnetism and high-magnetic field magnetization in alkali superoxide CsO2 ,” J. Phys. Soc. Jpn. 87, 063704-1–4 (2018).
T. Suzuki, K. Katayama, I. Kawasaki, I. Watanabe, H. Tanaka, “Spin fluctuations in the spin-1/2 kagome lattice antiferromagnet(Rb1−x Cs x )2 Cu3 SnF12 around the quantum critical point detected by muon-spin relaxation technique,” J. Phys. Soc. Jpn. 87, 074708-1–6(2018).
T. Kawamata, K. Ohashi, T. Takamatsu, T. Adachi, M. Kato, I. Watanabe, Y. Koike, “Impurity eﬀects on the electronic state in theunderdoped (Cu-free) superconductor T′ -La1.8 Eu0.2 CuO4 studied by muon spin relaxation,” J. Phys. Soc. Jpn. 87, 094717 (2018).
S. N. A. Afmad, S. Sulaiman, L. S. Ang, I. Watanabe, “First-principle studies on magnetic structure and exchange interactions of βEtn Me4−n Z[Pd(dmit)2 ]2 ,” J. Phys. Soc. Jpn. 87, 124709-1–6 (2018).
F. Astuti, M. Miyajima. T. Fukuda. M. Kodani, T. Nakano, T. Kambe, I. Watanabe, “Anionomagnetiam combined lattice symmetry inalkali-metal superoxide RbO2 ,” J. Phys. Soc. Jpn. 88, 043701 (2018).
K. L. Brown, C. P. J. Stockdale, H. Luo, X. Zhao, J. -H. Li, D. Viehland, G. Xu, P. M. Gehring, K. Ishida, A. D. Hillier, C. Stock, “Depth
dependent element analysis of PbMg1/3 Nb2/3 O3 using muonic X-rays,” J. Phys. Conds. Matt. 30, 125703 (2018). *Kumar, C. N. Cuo, F. Astuti, T. Shang, M. K. Lee, C. S. Lue, I. Watanabe, J. A. T. Baker, T. Shiroka, L. J. Chang, “Nodeless Superconductivity in the cage-type superconductor Sc5 Ru6 Sn18 with Preserved time-reversal symmetry,” J. Phys. Conds. Matt. 30, 315803-1–11(2018).
E. Mocchiutti et al. (FAMU collaboration), “FAMU: study of the energy dependent transfer rate Λµp → µO,” J. Phys. C 1138, 2018. *E. Spurayoga, A. A. Nugroho, D. Onggo, A. O. Polyakov, T. T. M. Palstra, I. Watanabe, “3D long-range magnetic ordering in(C2 H5 NH3 )2 CuCl4 compound revealed by internal magnetic field from muon spin rotation and first principal calculation,” Physica
B 545, 76–79 (2018).
M Clemenza et al., “CHNET TANDEM experiment: Use of negative muons at RIKEN-RAL Port 4 for elemental characterization of
Nuragic votive ship samples,” Nucl. Instrum. Methods Phys. Res. A, https://doi.org/10.1016/j.nima.2018.11.076 . *K. Kurashima, T. Adachi, Kensuke M. Suzuki, Y. Fukunaga, T. Kawamata, T. Noji, H. Miyasaka, I. Watanabe, M. Miyazaki, A. Koda,
R. Kadono, Y. Koike, “Development of Ferromagnetic fluctuations in heavily overdoped (Bi, Pd)2 Sr2 CuO6+δ coper oxides,” Phys. Rev.
Lett. 121, 057002-1–6 (2018).

[Proceedings](Original Papers) *Subject to Peer Review
B. V. Hampshire, K. Butcher, K. Ishida, G. Green, D. Paul, A. Hillier, “Using negative muons as a probe for depth profiling silver Roman
coinage,” Heritage 2, 400–407 (2019), Proc. of the 8th International Conference on Synchrotron Radiation and Neutrons in Art andArchaeology, doi:10.3390/heritage2010028. *T. Sumura, T. Ishimoto, H. Kuwahara, K. Kurashima, Y. Koike, I. Watanabe, M. Yiyazaki, A. Koda, R. Kadono, T. Adachi, “Reduction Eﬀects on Cu-spin Fluctuation in the electron-doped T ′ -cuprate Pr1.3−x La0.7 Ce x CuO4+δ (x = 0.10),” JPS Conf. Proc. 21, 011027(2018). *A. Hillier, K. Ishida, P. Seller, M. C. Veale, M. D. Wilson, “Element specific imaging using muonic x-rays,” JPS Conf. Proc. 21, 011042(2018).
Risdiana, T. Saragi, W. A. Somantri, S. Pratiwi, D. Suhendar, M. Manawan, B. J. Suroto, I. Watanabe, “Zn-induced development of the
Cu-spin Correlation in electron-doped superconducting cuprates of Eu2−x Ce x CuO4 ,” J. Phys. Conf. Ser. 1013, 012180-1–5 (2018). *S. Kanda, K. Ishida, M. Iwasaki, Y. Ma, S. Okada, A. Takamine, H. Ueno, K. Midorikawa, N. Saito, S. Wada, M. Yumoto, Y. Oishi,
M. Sato, S. Aikawa, K. S. Tanaka, Y. Matsuda, “Measurement of the proton Zemach radius from the hyperfine splitting in muonichydrogen atom,” J. Phys. Conf. Ser. 1138, 012008 (2018). 10th Int. Conf. on Precision Physics of Simple Atomic Systems. *A. D. Hillier, J. S. Lord, K. Ishida, C. Rogers “Muons at ISIS,” Philos. Trans. R. Soc. A 377, 20180064 Contribution to a Theo Murphy
meeting issue “Cosmic-ray muography.” *S. Kanda, K. Ishida, M. Iwasaki, Y. Ma, A. Takamine, H. Ueno, K. Midorikawa, N. Saito, S. Wada, M. Yumoto, S. Okada, Y. Oishi,
M. Sato, S. Aikawa, K. S. Tanaka, Y. Matsuda, “Precision laser spectroscopy of the ground state hyperfine splitting in muonic hydrogen,” Proc. Sci. NuFact2017, 122 (2018). *- 392 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Oral Presentations[International Conference etc.]
S. Kanda, “Precision Spectroscopy of muonic systems with high-intensity pulsed muon beam,” Workshop on Lepton Flavor Physics with
Most Intense DC Muon Beams, Tokyo, April, 2018.
S. Kanda, “Measurement of the proton Zemach radius from the hyperfine splitting in muonic hydrogen atom,” 10th International Conference on Precision Physics of Simple Atomic Systems (PSAS 2018), Vienna, May, 2018.
K. Ishida, “Future opportunities in mu-p atoms,” FAMU meeting, Trieste, Italy, June, 2018.
S. Kanda, “Laser spectroscopy of the hyperfine splitting in muonic hydrogen atom by a measurement of decay electron asymmetry,”
Sohtaro Kanda, Nucleon Spin Structure at Low Q: A Hyperfine View, Trento, July, 2018.
S. Kanda, “Precision spectroscopy of exotic atoms involving muon,” The 20th International Workshop on Neutrinos from Accelerators(NuFact2018), Virginia, August, 2018.
S. Kanda, “Laser spectroscopy of the ground-state hyperfine splitting in muonic hydrogen atom,” Symposium for Muon and Neutrino
Physics 2018, Osaka, September, 2018.
K. Ishida, “Proton Zemach radius measurement by the hyperfine splitting of muonic hydrogen (invited),” The Fifth Joint Meeting of the
Nuclear Physics Divisions of the American Physical Society and the Physical Society of Japan, Waikoloa, USA, October, 2018.
K. Ishida, “Proton radius measurement with muonic atoms,” International workshop on the structure of the proton, Sagae, Yamagata,February, 2019.
S. Kanda, “Development of instruments for the proton radius measurement at RIKEN,” International workshop on the structure of the
proton, Sagae, Yamagata, February, 2019.

[Domestic Conference]ੴాউ඙, ʮϛϡΦϯ‫ʹࢠݪ‬ΑΔཅࢠ൒‫ܾܘ‬ఆʯ, େࡕେֶཧֶ෦෺ཧηϛφʔ, ๛த, 2018 ೥ 8 ݄.
ਆా૱ଠ࿠, “Residual polarization and hyperfine transition rate in muonic hydrogen,” ৽ֶज़ྖҬ‫ڀݚ‬ʮӉ஦‫؍‬ଌ‫ݕ‬ग़‫ࢠྔͱث‬ϏʔϜͷग़ձ͍. ৽ͨͳԠ༻΁ͷՍ͚‫ڮ‬.ʯ, ΩοΫΦϑγϯϙδ΢Ϝ, ౦๺, 2018 ೥ 12 ݄.
ਆా૱ଠ࿠, “Laser spectroscopy of the hyperfine splitting in muonic hydrogen,” ୈ 9 ճ Muon ՊֶͱՃ଎‫ڀݚڀݚث‬ձ, େࡕ, 2019
೥ 1 ݄.
ੴాউ඙, ʮཧ‫ ݚ‬RAL ϛϡΦϯࢪઃʯ, ୈ 9 ճʮMuon ՊֶͱՃ଎‫ڀݚث‬ʯ, RCNP, ਧా, 2019 ೥ 1 ݄.
ੴాউ඙, ʮϛϡΦϯਫૉ‫ʹࢠݪ‬ΑΔ༝ࢤ൒‫ܘ‬ଌఆʯ, ELPH ‫ڀݚ‬ձ C021ʮిࢠࢄཚʹΑΔ‫—ڀݚ֩ࢠݪ‬ཅࢠ൒‫ܘ‬, ෆ҆ఆ֩ͷిՙີ౓෼෍Λத৺ʹ—ʯ, ౦๺େֶిࢠޫཧֶ‫ڀݚ‬ηϯλʔ, ઋ୆, 2019 ೥ 3 ݄.
ਆా૱ଠ࿠, ϛϡʔΦϯਫૉ‫ࢠݪ‬ͷϨʔβʔ෼ޫʹ޲͚ͨεϐϯճస࣮‫ݧ‬, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍େձ, ‫۝‬भେֶ, ෱Ԭ, 2019
೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 entrance and exit management system for which is the part of the radiation control system developed for the RILAC upgrade
was installed and started to operate. Interlock system will be set in the next year.
Minor improvements of the radiation safety systems were also done. The radiation monitors at the Nishina building has been
replaced annually from 2015 because they get older, which were installed in 1986.

Members
Group Director
Yoshitomo UWAMINO (–March 31, 2018)

Kanenobu TANAKA (April 1, 2018–)

Research/Technical Scientists
Rieko HIGURASHI (Technical Scientist)

Hisao SAKAMOTO (Technical Scientist)

Expert Technician
Atsuko AKASHIO
Research Consultant
Masaharu OKANO (Japan Radiation Res. Soc.)
Visiting Scientists
Noriaki NAKAO (Shimizu Corp.)
Nobuhiro SHIGYO (Kyushu Univ.)
Toshiya SANAMI (KEK)

Masayuki HAGIWARA (KEK)
Hiroshi YASHIMA (Kyoto Univ.)
Arim LEE (Pohang Accelerator Laboratory POSTECH)

Student Trainees
Kenta SUGIHARA (Kyushu Univ.)
Shougo IZUMITANI (Kyushu Univ.)

Eunji LEE (Kyushu Univ.)

Technical Staﬀ I
Hiroki MUKAI

Tomoyuki DANTSUKA (concurrent: Cryogenic Technology
Team)

Temporary Staﬃng
Ryuji SUZUKI
Part-time Workers
Kimie IGARASHI (Administrative Part-time Worker I)
Shin FUJITA (Part-time Worker)
Satomi IIZUKA (Administrative Part-time Worker II)
Hiroko AISO (Part-time Worker)

Naoko USUDATE (Administrative Part-time Worker II)
Hiroshi KATO (Part-time Worker)
Yukiko SHIODA (Administrative Part-time Worker II)- 394 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Assistant
Tomomi OKAYASU

List of Publications & Presentations
Publications
Oral Presentations[Domestic Conference]ాத৊৴, ʮཧԽֶ‫ ॴڀݚ‬RIBF Ճ଎‫ࢪث‬ઃͷՐࡂ࣌ରԠͱ‫ݸ‬ਓઢྔ؅ཧʹ͍ͭͯʯ, ୈ 6 ճՃ଎‫ࢪث‬ઃ҆શγϯϙδ΢Ϝ, ౦ւଜ,2018 ೥ 1 ݄.
ਿ‫݈ݪ‬ଠ, ཥԸஐ, ࣥߦ৴‫׮‬, ాத৊৴, ੺Ԙರࢠ, ࠤ೾ढ़࠸, ʮBi ʹର͢Δ 7 MeV/u α ೖࣹʹΑΔதੑࢠੜ੒ྔଌఆʯ, ೔ຊ‫ྗࢠݪ‬ֶձ 2019 ೥य़ͷ೥ձ, ਫ‫ށ‬, 2019 ೥ 3 ݄.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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
Group Director
Hideyuki SAKAI (–March 31, 2018)

Hideki UENO (April 1, 2019–)

Senior Visiting Scientists
Ikuko HAMAMOTO (Lund Univ.)

Munetake ICHIMURA (Univ. of Tokyo)

Assistants
Tomomi OKAYASU (Concurrent: Safety Management Grp.)
Yu NAYA

Yoko FUJITA
Midori YAMAMOTO- 396 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 (Concurrent: Industrial Application Research Team)- 397 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 (concurrent: Senior Research Scientist,
Radiation Laboratory)
Technical Staﬀ I
Narumasa MIYAUCHI (concurrent: Research Administrator,
Oﬃce of the Center Director)

List of Publications & Presentations
Outreach Activities
Hokkaido Science Festival 2018, Sapporo, Japan, August 6–7, 2018.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Partner Institutions

The Nishina Center established the “Research Partnership System” in 2008. This system permits an external institute to develop its own
projects at the RIKEN Wako campus in equal partnership with the Nishina Center. At present, two institutes, the Center for Nuclear
Study, the University of Tokyo (CNS); 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
System.
CNS and the Nishina Center signed the partnership agreement in 2008. Until then, 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 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 NPPAC meetings are co-hosted together with CNS and KEK.
The activities of CNS and KEK are reported in the following pages.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

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 theIsospin, Spin and Quark degrees of freedom play central roles. These researches in CNS lead to the understanding of the matter basedon common natures of many-body systems in various phases. We also aim at elucidating the explosion phenomena and the evolutionof the universe by the direct measurements simulating nuclear reactions in the universe. In order to advance the nuclear science withheavy-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 to obtain agood quality of low-energy beam. We added a new group for fundamental symmetry by using heavy RIs. We promote collaboration
programs at RIBF as well as RHIC-PHENIX and ALICE-LHC with scientists in the world, and host international meetings andconferences. We also provide educational opportunities to young scientists in the heavy-ion science through the graduate course as amember of the department of physics in the University of Tokyo and through hosting 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 includes development of ion sources, upgrading
the AVF cyclotron of RIKEN and the beam line to CRIB. In 2017, the operating time of the HyperECR was 2414 hours, which is
61% of the total operating time of the AVF cyclotron. The beam extraction system of the HyperECR is under development to realize
a high intensity and low emittance beam. We have succeeded to suppress 12 C4+ beam which contaminated 18 O6+ beam by measuring
the light intensity of the CIV line spectrum. The calculation model of injection beam orbit of the AVF cyclotron was completed
and the adjustment of the positon and angle deviation between the measured beam orbit and the calculated beam orbit is carried on.
The detailed studies on ion optics of the beamline to CRIB from AVF cyclotron were performed with beam diagnosis system andsimulation code, and it turned out the loss of the beam intensity is occurred at the entrance of the vertical deflection bending magnet.
(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 Sep. 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 collaboration of CNS,
INFN, Univ. Edinburgh and other institutes, in Oct. 2018. A measurement on 25 Al + p resonant scattering was performed at CRIB in
Feb. 2019, to study the resonances relevant for the astrophysical 22 Mg(α, p) reaction in X-ray bursters.
(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. In 2017, the following progress has been made. Experimental data taken under the EURICA collaboration has been
analyzed for studying octupole deformation in neutron-rich Ba isotopes and preparing publication. A new experiment measuring the4
He(8 He, 8 Be)4n reaction was performed for better statistics and better accuracy in order to verify a candidate of the ground state of
the tetra neutrons just above the 4n threshold, which is under analysis.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(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 involved in the ALICE-TPC upgrade using a Gas Electron Multiplier (GEM). Development of the new data readout
system for the upgrade, which aims online data processing by utilizing FPGA and GPU, has been ongoing in 2017.
(5) Nuclear Theory
The nuclear theory group participates a project, “Priority Issue 9 to be tackled by using the Post-K Computer” and promotes
computational nuclear physics utilizing supercomputers. In FY2017, we performed the Monte Carlo shell model calculations of the
Sn isotopes and revealed that the anomalous enhancement of the B(E2) transition probabilities in the neutron-deficient region is causedby the proton excitation from the 1g9/2 orbit, and found that the second-order quantum phase transition occurs around N = 66. Wealso investigated the double Gamow-Teller strength distribution of double-beta decay emitters, such as 48 Ca. We theoretically predicta linear relation between the nuclear matrix elements of the double Gamow-Teller transition and the neutrinoless double beta decay. In
parallel, we have been promoting the CNS-RIKEN collaboration project on large-scale nuclear structure calculations and performed
shell-model calculations under various collaborations with many experimentalists for investing the exotic structure of neutron-richnuclei, such as 35 Mg, 136 Ba, 138 Ce, and 135 La.
(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 tounderstand 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 lattice at
RIBF. The developments of a high intensity surface ionizer to produce Fr and a magneto-optical trap (MOT) are in progress, and
Fr-MOT experiments are going on at present at CYRIC.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Members
Director
Susumu SHIMOURA
Scientific Staﬀ
Susumu SHIMOURA (Professor)
Hidetoshi YAMAGUCHI (Lecturer)
Yasuhiro SAKEMI (Professor)
Shin’ichiro MICHIMASA (Assistant Professor)
Kentaro YAKO (Associate Professor)

Taku GUNJI (Associate Professor)
Nobuaki IMAI (Associate Professor)
Shinsuke OTA (Assistant Professor)
Noritaka SHIMIZU (Project Associate Professor)
Hiroki NAGAHAMA (Assistant Professor)

Guest Scientists
Yutaka UTSUNO (Guest Professor)
Yutaka MIZOI (Guest Associate Professor)

Ningtao ZHANG (Guest Post Doctoral Associate)

Technical Staﬀ
Yasuteru KOTAKA
Techinical Assistants
Yukimitsu OHSHIRO
Reiko KOJIMA
Mamoru KATAYANAGIHiroshi KUREI
Masayoshi YAGYU

Project Research Associates
Tomoaki TOGASHIOlga BELIUSKINA
Masanori DOZONO

Seiya HAYAKAWA
Takashi ABE
Naofumi TSUNODA

Post Doctoral Associates
Shinichi HAYASHI
Chihiro IWAMOTO
Philipp SCHROCKLei YANG
Laszlo STUHL
Yusuke TSUNODA

Javier MENENDEZ SANCHEZ
Jongwon HWANG
Takayuki MIYAGISatoshi TAKEUCHI
Tomohiro HAYAMIZU

Assistant Teaching Staﬀ
Hiroshi TOKIEDA
Motonobu TAKAKI

Yuko SEKIGUCHI

Graduate Students
Ryo NAKAJIMA
Soichiro MASUOKA
Noritaka KITAMURA
Keita KAWATA

Hideki SHIMIZU
Rieko TSUNODA
Naoya OZAWA

Administration Staﬀ
Toshio OSUGI
Ikuko YAMAMOTO
Mikio OKI

Takako ENDO
Yukino KISHI

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
T. Nishi, K. Itahashi, G. P. A. Berg, H. Fujioka, N. Fukuda, N. Fukunishi, H. Geissel, R. S. Hayano, S. Hirenzaki, K. Ichikawa, N. Ikeno,
N. Inabe, S. Itoh, M. Iwasaki, D. Kameda, S. Kawase, T. Kubo, K. Kusaka, H. Matsubara, S. Michimasa, K. Miki, G. Mishima,
H. Miya, H. Nagahiro, M. Nakamura, S. Noji, K. Okochi, S. Ota, N. Sakamoto, K. Suzuki, H. Takeda, Y. K. Tanaka, K. Todoroki,
K. Tsukada, T. Uesaka, Y. N. Watanabe, H. Weick, H. Yamakami, K. Yoshida, “Spectroscopy of pionic atoms in 122 Sn(d, 3 He) reaction
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Phys. Rev. C 97, 044324 (2018). *A. I. Morales, T. Otsuka, Y. Tsunoda, “Is seniority a partial dynamic symmetry in the first νg9/2 shell?,” Phys. Lett. B 781, 706 (2018). *T. Togashi, Y. Tsunoda, T. Otsuka, N. Shimizu, M. Honma, “Novel shape evolution in Sn isotopes from magic numbers 50 to 82,” Phys.
Rev. Lett. 121, 062501 (2018). *B. A. Marsh, Y. Tsunoda, T. Otsuka, “Characterization of the shape-staggering eﬀect in mercury nuclei,” Nature Physics 14, 1163 (2018). *P. Singh, T. Otsuka, T. Togashi, Y. Tsunoda, “Evidence for coexisting shapes through lifetime measurements in 98 Zr,” Phys. Rev. Lett.
121, 192501 (2018). *D. Rosiak, Y. Tsunoda, T. Togashi, T. Otsuka, “Enhanced quadrupole and octupole strength in doubly magic 132 Sn,” Phys. Rev. Lett. 121,
252501 (2018). *M. Stryjczyk, Y. Tsunoda, T. Otsuka, “β- decay study of the 66 Mn-66 Fe-66 Co-66 Ni decay chain,” Phys. Rev. C 98, 064326 (2018). *- 405 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Ł. W. Iskra, . . . , T. Otsuka, T. Togashi, Y. Tsunoda, . . . , “Revised B(E3) transition rate and structure of the 3− level in 96 Zr,” Phys. Lett. B
788, 396 (2018). *Y. Ichikawa, Y. Tsunoda, and T. Otsuka et al., “Interplay between nuclear shell evolution and shape deformation revealed by magnetic
moment of 75 Cu,” Nat. Phys. 15, 321 (2018). *C. Loelius, T. Otsuka, N. Tsunoda, “Enhanced electric dipole strength for the weakly bound states in 27 Ne,” Phys. Rev. Lett. 121, 262501(2018). *H. Nishibata, N. Tsunoda, T. Otsuka, “Structure of 31 Mg: Shape coexistence revealed by β-γ spectroscopy with spin-polarized 31 Na,”
Phys. Rev. C 99, 024322 (2018). *[Proceedings](Original Papers) *Subject to Peer Review
N. Imai, “Nuclear reaction data of low-energy LLFP produced by OEDO,” Proceedings of the 2017 Symposium on Nuclear Data, JAEAConf2018-001, 39–44 (2018). *M. La Commara, M. Mazzocco, A. Boiano, C. Boiano, C. Manea, C. Parascandolo, D. Pierroutsakou, C. Signorini, E. Strano, D. Torresi,
H. Yamaguchi, D. Kahl, P. DiMeo, J. Grebosz, N. Imai, Y. Hirayama, H. Ishiyama, N. Iwasa, S. C. Jeong, H. M. Jia, Y. H. Kim,
S. Kimura, S. Kubono, C. J. Lin, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, Y. Sakaguchi, A. M. Sanchez-Benitez, F. Soramel,
T. Teranishi, Y. Wakabayashi, Y. X. Watanabe, L. Yang, Y. Y. Yang, “8 B + 208 Pb elastic scattering at Coulomb barrier energies,” IOP
Conf. Series: J. Phys. Conf. Ser. 966, 012010 (2018) . *D. Kahl, H. Shimizu, 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. Kwag, J. Liang, J. Y. Moon, S. Nishimura, S. Oka, S. Y. Park, A. Psaltis, T. Teranishi,
Y. Ueno, L. Yang, “Impact of the 26m Al(p, γ) reaction to galactic 26 Al yield,” AIP Conf. Proc. 1947(1), 020003 (2018). *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. Kiss, S. Kubono, M. L. Cognata, M. L. 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. D. Tang, O. Trippella, A. Tumino, P. Vi, H. Yamaguchi, L. Yang, N. T. Zhang, “Measurements of the neutron-induced reactions on
7
Be with CRIB by the trojan horse method,” AIP Conf. Proc. 1947(1), 020011 (2018). *H. Yamaguchi, D. Kahl, S. Hayakawa, L. Yang, H. Shimizu, Y. Sakaguchi, K. Abe, Y. Wakabayashi, T. Hashimoto, T. Nakao, S. Kubono,T. Suhara, N. Iwasa, A. Kim, D. H. Kim, S. M. Cha, M. S. Kwag, J. H. Lee, E. J. Lee, K. Y. Chae, N. Imai, N. Kitamura, P. Lee,J. Y. Moon, K. B. Lee, C. Akers, H. S. Jung, N. N. Duy, L. H. Khiem, C. S. Lee, S. Cherubini, M. Gulino, C. Spitaleri, G. G. Rapisarda,
M. L. Cognata, L. Lamia, S. Romano, A. Coc, N. de Sereville, F. Hammache, G. Kiss, S. Bishop, T. Teranishi, T. Kawabata, Y. K. Kwon,
D. N. Binh, “Indirect studies on astrophysical reactions at the low-energy RI beam separator CRIB,” AIP Conf. Proc. 1947(1), 020022(2018). *H. Yamaguchi, S. Hayakawa, L. Yang, H. Shimizu, D. Kahl, “Direct measurements and detection techniques with low-energy RIBs,” EPJ
Web Conf., 184, 01017 (2018). *A. Inoue, A. Tamii, K. Abe, S. Adachi, N. Aoi, M. Asai, M. Fukuda, G. Gey, T. Hashimoto, E. Ideguchi, J. Isaak, N. Kobayashi, Y. Maeda,
H. Makii, K. Matsuta, M. Mihara, M. Miura, T. Shima, H. Shimizu, R. Tang, T. Dinh Trong, H. Yamaguchi, L. Yang, “Study of thecontribution of the 7 Be(d, p) reaction to the 7 Li problem in the Big-Bang Nucleosynthesis,” EPJ Web Conf. 184, 02007 (2018). *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, L. Yang, “Isomeric 26 Al beam production with CRIB,” EPJ Web Conf. 184, 02013 (2018). *M. Gulino, S. Cherubini, G. G. Rapisarda, S. Kubono, L. Lamia, M. L. Cognata, R. G. Pizzone, H. Yamaguchi, S. Hayakawa, Y. Wakabayashi, N. Iwasa, S. Kato, T. Komatsubara, T. Teranishi, A. Coc, N. Sereville, F. Hammache, G. Kiss, S. Bishop, D. N. Binh,
B. Roeder, L. Trache, R. Tribble, R. Sparta, I. Indelicato, C. Spitaleri, “Trojan Horse Method experiments with radioactive ion beams,”
EPJ Web Conf. 184, 01008 (2018). *E. Strano, M. Mazzocco, A. Boiano, C. Boiano, M. La Commara, C. Manea, C. Parascandolo, D. Pierroutsakou, C. Signorini, D. Torresi,
H. Yamaguchi, D. Kahl, L. Acosta, P. Di Meo, J. P. Fernandez-Garcia, T. Glodariu, J. Grebosz, A. Guglielmetti, N. Imai, Y. Hirayama,
H. Ishiyama, N. Iwasa, S. C. Jeong, H. M. Jia, N. Keeley, Y. H. Kim, S. Kimura, S. Kubono, J. A. Lay, C. J. Lin, G. MarquinezDuran, I. Marte, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, A. Pakou, K. Rusek, Y. Sakaguchi, A. M. Sanchez-Benitez, T. Sava,
O. Sgouros, C. Stefanini, F. Soramel, V. Soukeras, E. Stiliaris, L. Stroe, T. Teranishi, N. Toniolo, Y. Wakabayashi, Y. X. Watanabe,
L. Yang, Y. Y. Yang, “7 Be and 8 B reaction dynamics at Coulomb barrier energies,” EPJ Web Conf. 184, 02015 (2018). *M. Mazzocco, 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, N. Imai, Y. Hirayama,
H. Ishiyama, N. Iwasa, S. C. Jeong, H. M. Jia, N. Keeley, Y. H. Kim, S. Kimura, S. Kubono, J. A. Lay, C. J. Lin, G. MarquinezDuran, I. Marte, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, A. Pakou, K. Rusek, Y. Sakaguchi, A. M. Sanchez-Benitez, T. Sava,
O. Sgouros, F. Soramel, V. Soukeras, E. Stiliaris, L. Stroe, T. Teranishi, N. Toniolo, Y. Wakabayashi, Y. X. Watanabe, L. Yang,
Y. Y. Yang, Reaction Dynamics for the Systems “7 Be, 8 B + 208 Pb at Coulomb Barrier Energies,” IOP Conf. Series: J. Phys. Conf. Ser.
1078, 012013 (2018). *N. Tsunoda, T. Otsuka, N. Shimizu, “Structure of exotic nuclei based on nuclear force,” Proceedings of the Ito International ResearchCenter Symposium “Perspectives of the Physics of Nuclear Structure,” 23, 012014. (2018). *T. Abe, “Advances in the Monte Carlo Shell Model for Understanding Nuclear Structure,” JPS Conf. Proc. 23, 012009 (2018). *J. Menéndez, “Towards reliable nuclear matrix elements for neutrinoless ββ decay,” Proceedings of the “Symposium on Perspectives of
the Physics of Nuclear Structure,” JPS Conf. Proc. 23, 012036 (2018). *- 406 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

T. Miyagi, T. Abe, M. Kohno, P. Navrátil, R. Okamoto, T. Otsuka, N. Shimizu, S. R. Stroberg, “Nuclear Ab Initio Calculations with theUnitary-Model-Operator Approach,” JPS Conf. Proc. 23, 013007 (2018). *Oral Presentations[International Conference etc.]
S. Shimoura (Invited), “Tetra-neutron and few-body correlations studied by RI-beam experiments,” New Frontiers in Nuclear Physics andAstrophysics (NNPA), Antalya, Turkey, June 1–May 28, 2018.
S. Shimoura (Invited), “Tetraneutron system populated by double-charge exchange reactions using RI beam,” The 13th International
Conference on Hypernuclear and Strange Particle Physics (HYP2018), Portsmouth, Virginia, USA, June 24–29, 2018.
S. Shimoura (Invited), “Tetra-neutron system populated by RI-beam induced reactions,” The 22nd International Conference on Few-Body
Problems in Physics (FB22), Caen, France, July 9–13, 2018.
S. Shimoura (Invited), “Nuclear Reaction Data for Long-Lived Fission Products,” ImPACT International Symposium on “New Horizonsof Partitioning and Transmutation Technologies with Accelerator System,” The University of Tokyo, December 2–3, 2018.
S. Shimoura (Invited), “Tetra-neutron system populated by exothermic double-charge exchange reaction,” 13th International Conferenceon Nucleus-Nucleus Collisions (NN2018), Omiya, Saitama, December 4–8, 2018.
N. Imai (Invited), “Experimental studies with the energy-degraded RI beams,” 20th Northeastern Asia symposium, Nagoya, Japan,
September 19, 2018.
S. Michimasa (Invited), “Overview of OEDO,” International OEDO Workshop 2018, Wako, Japan, June 11, 2018.
M. Dozono (Invited), “Status report of ImPACT17-02-01/02,” International OEDO Workshop 2018, Wako, Japan, June 11, 2018.
N. Imai (Oral), “Measurement of 77, 79 Se(d, p) reactions in inverse kinematics at OEDO,” The 10th international conference on Direct
Reaction with Exotic Beams (DREB2018), Matsue, Japan, June 4–8, 2018.
S. Michimasa (Oral), “New energy-degrading beam line for in-flight RI beams, OEDO,” The International Conference on Electromagnetic
Isotope Separators and Related Topics (EMIS), CERN Geneva, Switzerland, September 16–21, 2018.
S. Michimasa (Oral), “Construction of Low-energy RI Beam Line at RIBF and Nuclear Reaction Data on Low-energy LLFPs,” Fifteenth
NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation, Manchester Hall, Manchester,
UK, September 30–October 3, 2018.
S. Michimasa (Invited), “Recent Achievements using OEDO-SHARAQ at RIBF,” The 10th China-Japan Joint Nuclear Physics Symposium (CJNP2018), Sheraton Bailuhu Resort Hotel, Houzhou, China, November 18–23, 2018.
S. Ota (Invited), “Active target technique with medium-energy high-intensity heavy-ion beams,” The 10th China-Japan Joint Nuclear
Physics Symposium (CJNP2018), Sheraton Bailuhu Resort Hotel, Huizhou, China, November 18–23, 2018.
N. Imai (Invited), “Surrogate reaction of 79 Se(n, γ),” The 5th Joint Meeting of the APS Division of Nuclear Physics and the PhysicalSociety of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
S. Michimasa (Oral), “Direct mass measurements of very neutron-rich calcium isotopes beyond N = 34,” The 5th Joint Meeting of the
APS Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
M. Dozono (Oral), “Nuclear reaction study for long-lived fission products in nuclear waste: Proton-and deuteron-induced reactions on
107
Pd and 93 Zr at 20–30 MeV/u,” The 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan,
Waikoloa, Hawaii, USA, October 23–27, 2018.
S. Ota (Invited), “Experimental study of the isospin dependence of nuclear incompressibility,” The 5th Joint Meeting of the APS Divisionof Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
S. Masuoka (Oral), “Re-measurement of 4 He(8 He, 8 Be) reaction,” The 5th Joint Meeting of the APS Division of Nuclear Physics and the
Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
R. Tsunoda (Oral), “Proton resonance scattering of a shape-coexistence nucleus 118 Sn,” The 5th Joint Meeting of the APS Division of
Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
K. Kawata (Oral), “Production of isomers around 52 Fe nucleus via projectile fragmentation,” The 5th Joint Meeting of the APS Divisionof Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
L. Stuhl (Oral), “Study of spin-isospin responses of radioactive nuclei with background free neutron spectrometer, PANDORA International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS2018),” CERN, Geneva, Switzerland, September
16–21, 2018.
L. Stuhl (Invited), “Detector development for (p, n) measurements at RIKEN RIBF,” Nuclear Physics In Stellar Explosions Workshop,
Debrecen, Hungary, September 12–14, 2018.
L. Stuhl (Oral), “Overview of campaign type experiments at SAMURAI—The 18 O campaign,” SAMURAI International Workshop 2018,
RIKEN Nishina Center, Wako, Japan, September 3–4, 2018.
L. Stuhl (Oral), “Status of (p, n) measurements at SAMURAI,” SAMURAI International Workshop 2018, RIKEN Nishina Center, Wako,
Japan, September 3–4, 2018.
L. Stuhl (Oral), “Study of spin-isospin responses of light nuclei along the drip line with PANDORA,” The 10th international conference
on Direct Reactions with Exotic Beams (DREB2018), Matsue, Japan, June 4–8, 2018.
H. Tokieda (Oral), “CNS Active Target (CAT) for high-intensity heavy-ion beam experiment,” The 5th Joint Meeting of the APS Divisionof Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
C. Iwamoto (Oral), “Performance evaluation of Dual Gain Multi-layer Thick GEM for CAT with high-intensity heavy-ion beams,” The
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27,- 407 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)2018.
S. Ota (Oral), “Giant resonances in Tin-region nuclei,” 6th International Conference on Collective Motion in Nuclei under Extreme
Conditions, Cape town, South Africa, October 29–November 2, 2018.
Y. Sekiguchi (Oral), “Long-range two-particle correlations,” Second internal workshop on Collectivity in Small Collision Systems(CSCS2018), Wuhan, China, June 13–15, 2018.
Y. Sekiguchi for the ALICE Collaboration (Oral), “Long range angular correlations in p-Pb collisions with ALICE,” The 5th Joint Meetingof the APS Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
S. Hayashi for the ALICE Collaboration (Oral), “J/ψ production in p-Pb collisions with the ALICE detector,” The 5th Joint Meeting of
the APS Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
S. Hayashi for the ALICE Collaboration (Oral), “J/ψ production in p-Pb collisions with the ALICE detector,” The 7th Asian Triangle
Heavy Ion Conference (ATHIC2018), Hefei, China, November 3–6, 2018.
Y. Sekiguchi for the ALICE Collaboration (Oral), “Two-particle correlations with ALICE,” The 7th Asian Triangle Heavy Ion Conference(ATHIC2018), Hefei, China, November 3–6, 2018.
S. Hayashi for the ALICE Collaboration (Oral), “Quarkonium production in pp, pA, and AA collisions,” Quark and Nuclear Physics 2018
(QNP2018), Tsukuba, Japan, November 13–17, 2018.
T. Gunji (Oral), “Extension of Forward Physics beyond 2030,” International workshop on Forward Physics and Forward Calorimeter
upgrade in ALICE, Tsukuba, Japan. March 7–9, 2019.
L. Yang (Oral), “Reaction mechanisms of 17 F + 58 Ni at energies around the Coulomb barrier,” DREB2018, Kunibiki Messe, Matsue,
Shimane, Japan, June 4–8, 2018.
H. Yamaguchi (Oral), “Study on explosive nuclear synthesis with low-energy RI beams at CRIB,” 15th International Symposium on
Nuclei in the Cosmos, LNGS, Assergi, Italy, June 24–29, 2018.
S. Hayakawa (Oral), “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,” 15th International Symposium on Nuclei in the Cosmos, LNGS, Assergi,
Italy, June 24–29, 2018.
H. Yamaguchi (Oral), “Activities at the low-energy RI beam separator CRIB,” RIBF Users Meeting 2018, RIKEN, Wako, Saitama, Japan,
September 5–6, 2018.
H. Yamaguchi (Invited), “Indirect method application for RI-beam experiments,” ECT* Workshop “Indirect Methods in Nuclear Astrophysics,” ECT*, Trento, Italy, November 5–9, 2018.
H. Yamaguchi (Invited), “Studies on nuclear astrophysics and nuclear clustering with low-energy RI beams at CRIB,” 13th International
Conference on Nucleus-Nucleus Collisions (NN2018), Omiya, Saitama, Japan, December 4–8, 2018.
H. Yamaguchi (seminar), “Study on cluster states in unstable nuclei with alpha-resonant scattering,” RIBF Nuclear Physics Seminar,
RIKEN, Wako, Saitama, Japan, January 8, 2019.
K. Harada (Oral), “Magneto-optical trapping of radioactive francium atoms: toward search for electron electric dipole moment,” 11th
Fundamental Physics using Atoms, OIST, Okinawa, Japan, March 1–4, 2019.
H. Nagahama (Oral), “A new approach to high-precision measurements of the electron EDM using francium atoms,” The 5th Joint Meetingof the APS Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
H. Nagahama (Invited), “High-precision measurements for testing CP and CPT symmetry,” 3rd ETH Zurich-The University of Tokyo
Strategic Partnership Symposium on the UN Sustainable Development Goals and Innovation, The University of Tokyo, Japan, January
21–22, 2019.
T. Abe (Oral), “Recent advances of the no-core Monte Carlo shell model,” GANIL Workshop on Nuclear Structure and Reactions for the
2020s, GANIL, Caen, France, July, 2018.
T. Abe (Oral), “Large-scale computation of the no-core Monte Carlo shell model for nuclear many-body problems,” The 5th Joint Meetingof the APS Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
T. Abe (Oral), “Recent results and implications of no-core MCSM calculations for nuclear structure,” The 5th Joint Meeting of the APS
Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
T. Abe (Oral), “No-core Monte Carlo shell model calculations with Daejeon16 NN interaction,” International Conference “Nuclear Theory
in the Supercomputing Era – 2018” (NTSE-2018), IBS, Daejeon, Korea, November, 2018.
T. Abe (Oral), “Recent advances in the no-core Monte Carlo shell model for the alpha clustering nature in light nuclei,” International
workshop on “Recent advances in nuclear structure physics 2018” (RANSP2018), YITP, Kyoto, Japan, November 2018.
T. Abe (Oral), “Alpha-cluster structure from no-core Monte Carlo shell model (oral),” The 50th Reimei workshop on Universal Physics
in Many-Body Quantum Systems —From Atoms to Quarks—, JAEA, Ibaraki, Japan, December 2018.
T. Abe (Oral), “Alpha-cluster structure from no-core Monte Carlo shell model,” TRIUMF Theory Workshop on “Progress in Ab Initio
Techniques in Nuclear Physics,” TRIUMF, Vancouver, Canada, March 2019.
N. Shimizu (Oral), “Large-scale shell model calculations and chiral doublet of 128 Cs,” International Conference, Nuclear Theory in the
Supercomputing Era 2018 (NTSE-2018), November 2018.
N. Shimizu (Oral), “Double Gamow Teller transition and its relation to neutrinoless double beta decay matrix element,” The 5th Joint
Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
N. Shimizu (Oral), “Shell-model study in A ∼ 130 nuclei and chiral doublet of 128 Cs,” The 9th international workshop “Quantum Phase
Transitions in Nuclei and Many-body Systems,” Padova, Itally, May, 2018.
֯ా༎հ (Invited), “Shapes of Medium-mass Nuclei Studied by Monte Carlo Shell Model Calculations,” Nuclear Structure 2018

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)(NS2018), Michigan State University, Michigan, USA, August 2018.
֯ా༎հ (Invited), “Large-scale shell model calculations for structure of Ni and Cu isotopes,” The 5th Joint Meeting of the APS Divisionof Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
N. Tsunoda (Oral), “Physics in the island of inversion starting from the first principle,” Shapes and Symmetries in Nuclei: from Experiment
to Theory (SSNET’18 conference), Gif-Sur Yvette, France, October 2018.
N. Tsunoda (Oral), “Study of neutron-rich nuclei via nuclear force and microscopic theory,” The 5th Joint Meeting of the APS Divisionof Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
J. Menéndez (Invited), “Double Gamow-Teller transitions in connection to neutrinoless double-beta decay,” ECT* Workshop “Exploring
the role of electro-weak currents, in Atomic Nuclei,” Trento, Italy, April 2018.
J. Menéndez (Invited), “Current status of neutrinoless double beta decay matrix elements,” 13th Conference on the Intersections of Particle
and Nuclear Physics (CIPANP 2018), Indian Wells, USA, May 2018.
J. Menéndez (Invited), “Neutrinoless double-beta decay and direct dark matter detection,” INT Workshop “From nucleons to nuclei:
enabling discovery for neutrinos, dark matter and more,” Seattle, USA, June 2018.
J. Menéndez (Invited), “Double charge exchanges for double beta decays,” Symposium “Neutrinos and Dark Matter in Nuclear Physics(NDM18),” Daejeon, South Korea, July 2018.
J. Menéndez (Invited), “Recent progress on neutrinoless double-beta decay nuclear matrix elements,” “Double-Beta Decay and Underground Science,” The 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii,
USA, October 23–27, 2018.
J. Menéndez (Invited), “Nuclear observables to constrain neutrinoless double-beta decay,” The 5th Joint Meeting of the APS Division of
Nuclear Physics and the Physical Society of Japan, Waikoloa, Hawaii, USA, October 23–27, 2018.
J. Menéndez (Invited), “Nuclear matrix elements to unveil the nature of neutrinos and dark matter,” Conference “Shapes and Symmetries
in Nuclei: from Experiment to Theory (SSNET’18),” Gif-sur-Yvette, France, November 2018.
T. Miyagi (Oral), “Recent progress in the unitary-model-operator approach,” TRIUMF workshop on Progress in Ab Initio Techniques in
Nuclear Physics, Vancouver, Canada, February–March 2018.

[Domestic Conference]ԼӜ‫( ڗ‬Oral), ʮ֩ม‫׵‬ɿ৽ͨͳ֩ม‫׵‬ͷํ๏Λ୳Δʯ, ImPACT ϓϩάϥϜʮ֩ม‫ʹ׵‬ΑΔߴϨϕϧ์ࣹੑഇ‫غ‬෺ͷେ෯ͳ௿‫ݮ‬ɾࢿ‫ݯ‬Խʯެ։੒Ռใࠂձ—৽ͨͳબ୒ࢶͷఏҊ, ະདྷʹ޲͚ͯ—඼઒ΠϯλʔγςΟϗʔϧ, 2019 ೥ 3 ݄ 9 ೔.
D. Dozono (Invited), “r-process study with OEDO,” ‫ڀݚ‬ձʮॏྗ೾‫؍‬ଌ࣌୅ͷ r ϓϩηεͱෆ҆ఆ֩ʯ, Wako, Japan, June 20, 2018.
S. Michimasa (Invited), “Closed-shell property at N = 34 seen in the masses of neutron-rich Ca isotopes,” ೔ຊ෺ཧֶձୈ 74 ճ೥࣍ձ,‫۝‬भେֶ, ҏ౎Ωϟϯύε, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
M. Dozono (Oral), ʮ௿଎ RI ϏʔϜΛ༻͍ͨ 107 Pd ͷཅࢠɾॏཅࢠ༠‫ى‬൓Ԡଌఆʯ, ೔ຊ෺ཧֶձୈ 7 ճ೥࣍ձ, ‫۝‬भେֶ, ҏ౎Ωϟϯύε, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
S. Masuoka (Oral), ʮೋॏՙిަ‫׵‬൓Ԡ 4 He(8 He, 8 Be) ൓Ԡͷ࠶ଌఆ (II)ʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍ձ, ‫۝‬भେֶ, ҏ౎Ωϟϯύε,෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
J. W. Hwang (Oral), “Angle-tunable Degrader for a low-energy beamline,” ೔ຊ෺ཧֶձୈ 74 ճ೥࣍ձ, ‫۝‬भେֶ, ҏ౎Ωϟϯύε, ෱
Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
M. Dozono (Oral), ʮ௿଎ RI ϏʔϜΛ༻͍ͨ LLFP ֩ͷ֩൓Ԡσʔλଌఆʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2018 ೥ळͷେձ, Ԭࢁେֶ, ௡ౡΩϟϯύε, Ԭࢁ, 2018 ೥ 9 ݄ 5 ೔–7 ೔.
N. Imai (Oral), ʮ֩ม‫ʹ׵‬ΑΔߴϨϕϧ์ࣹੑഇ‫غ‬෺ͷେ෯ͳ௿‫ݮ‬ɾࢿ‫ݯ‬Խ (4-2) ୅ཧ൓ԠΛ༻͍ͨ 79 Se(n, γ)80 Se ൓Ԡஅ໘ੵධ
Ձ,” ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥य़ͷ೥ձ, ҵ৓େֶ, ਫ‫ށ‬Ωϟϯύε, ਫ‫ށ‬, 2019 ೥ 3 ݄ 20 ೔–22 ೔.
M. Dozono (Oral), ʮ֩ม‫ʹ׵‬ΑΔߴϨϕϧ์ࣹੑഇ‫غ‬෺ͷେ෯ͳ௿‫ݮ‬ɾࢿ‫ݯ‬Խ (4-3) ௿଎ RI ϏʔϜΛ༻͍ͨ LLFP ֩ͷཅࢠɾॏཅࢠ༠‫ى‬൓Ԡଌఆʯ, ೔ຊ‫ֶྗࢠݪ‬ձ 2019 ೥य़ͷ೥ձ, ҵ৓େֶ, ਫ‫ށ‬Ωϟϯύε, ਫ‫ށ‬, 2019 ೥ 3 ݄ 20 ೔–22 ೔.
Y. Sekiguchi (Oral), ʮ p + p ΍ p/d/He + A িಥʢখ͍͞‫ܥ‬ʣʹ͓͚Δूஂӡಈʯ, 35th Heavy Ion Café and 27th Heavy Ion Pub, June30, 2018. Nagoya, Japan.
T. Gunji (Oral), ʮEM ϓϩʔϒʯ, 35th Heavy Ion Café and 27th Heavy Ion Pub, Nagoya, Japan, June 30, 2018.
Y. Sekiguchi for the ALICE Collaboration (Oral), “Pseudorapidity dependence of anisotropic flow in p-Pb collisions with the ALICE
detector,” The Physical Society of Japan 2019 annual meeting, Fukuoka, Japan, March 14–17, 2019.
T. Gunji for the ALICE Collaboration (Oral), “Low mass dielectron measurements in pp and Pb-Pb collisions at LHC-ALICE,” The
Physical Society of Japan 2019 annual meeting, Fukuoka, Japan, March 14–17, 2019.
ञ‫ݟ‬ହ‫( ׮‬Invited), ʮਓ޻ RI ݁থʹΑΔ‫ج‬ຊରশੑͷ‫ڀݚ‬ʯ, ௒ॏ‫ݩ‬ૉ‫ڀݚ‬ͷ৽ల։ʢ‫ڀݚ‬ձʣ, ‫۝‬भେֶ, ෱Ԭ, 2018 ೥ 7 ݄ 30–31 ೔.
ञ‫ݟ‬ହ‫( ׮‬Invited), ʮޫ֨ࢠॏ‫ݩ‬ૉ‫ׯ‬ব‫ʹܭ‬ΑΔ‫ج‬ຊରশੑͷ‫ڀݚ‬ʯ, ෺࣭֊૚‫ݪ‬ཧ&ϔςϩք໘ʢ‫ڀݚ‬ใࠂձʣ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫΩϟϯύε, ࿨ޫ, 2019 ೥ 2 ݄ 5–6 ೔.
ञ‫ݟ‬ହ‫( ׮‬Invited), “Fundamental physics with laser cooled heavy elements,” 2019 ॏ‫ݩ‬ૉԽֶϫʔΫγϣοϓ, ཧԽֶ‫ॴڀݚ‬, ࿨ޫΩϟϯύε, ࿨ޫ, 2019 ೥ 3 ݄ 27–28 ೔.
௕ᖛ߂‫( ق‬Invited), ʮ‫ج‬ຊରশੑͷߴਫ਼౓‫ূݕ‬ʯ, RIBF एख์ஊձɿΤΩκνοΫ֩෺ཧͷকདྷ, ཧ‫ݚ‬ਆ‫ށ‬, ೔ຊ, 2019 ೥ 2 ݄.
ૣਫ༑༸ (Oral), ʮిࢠͷӬ‫ؾిٱ‬૒‫ࢠۃ‬Ϟʔϝϯτ୳ࡧ΁޲͚ͨϑϥϯγ΢Ϝ‫ࢠݪ‬ͷੜ੒ͱτϥοϓʯ, ೔ຊ෺ཧֶձୈ 74 ճ೥࣍ձ, ҏ౎Ωϟϯύε, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14 ೔–17 ೔.
֯ా༎հ (Oral), ʮϞϯςΧϧϩ֪໛‫ʹܕ‬ΑΔதॏ֩ͷߏ଄ͷ‫ڀݚ‬ʯ, ૉཻࢠɾ‫֩ࢠݪ‬ɾӉ஦ʮ‫͔ژ‬Βϙετ‫͚ͯ޲ʹژ‬ʯγϯϙδ΢Ϝ, ஜ೾େֶ౦‫ژ‬Ωϟϯύεจ‫ࣷߍژ‬, ౦‫ژ‬, January 2019.

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N. Tsunoda (Oral), “Physics in neutron-rich nuclei with the eﬀective interaction for the shell model based on nuclear force,” ೔ຊ෺ཧֶ
ձୈ 73 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄.
֯ా௚จ, ʮ‫֪֩ࢠݪ‬໛‫ܕ‬ͷ౷‫ֶྗܭ‬తཧղʯ, एख์ஊձɿΤΩκνοΫ֩෺ཧͷকདྷ, ཧ‫ݚ‬ਆ‫ށ‬, 2019 ೥ 2 ݄,֯ా௚จ, ʮதੑࢠա৒‫֩ࢠݪ‬ͷଘࡏ‫ݶ‬քͱͦͷ৽͍͠‫ݪ‬ཧ—֩ྗʹ‫ͮ͘ج‬େ‫ن‬໛‫ʹࢉܭ‬ΑΔղੳʯ, ૉཻࢠɾ‫֩ࢠݪ‬ɾӉ஦ʮ‫͔ژ‬Βϙετ‫͚ͯ޲ʹژ‬ʯγϯϙδ΢Ϝ, ஜ೾େֶ౦‫ژ‬Ωϟϯύεจ‫ࣷߍژ‬, ౦‫ژ‬, 2019 ೥ 1 ݄.
Ѩ෦‫( ڤ‬Invited), ʮେ‫ن‬໛਺஋‫ࢉܭ‬ͷ‫ͱࡏݱ‬ະདྷʯ, RIBF एख์ஊձ:ΤΩκνοΫ֩෺ཧͷকདྷ, ཧ‫ݚ‬ਆ‫ށ‬, 2019 ೥ 2 ݄.
ਗ਼ਫଇ޹ (Oral), ʮ੍‫ݶ‬ϘϧπϚϯϚγϯʹΑΔ֪໛‫ܕ‬೾ಈؔ਺ͷ‫ه‬ड़ʯ, ೔ຊ෺ཧֶձୈ 73 ճ೥࣍େձ, ෱Ԭ, 2019 ೥ 3 ݄.
ਗ਼ਫଇ޹ (Oral), ʮ֪໛‫ʹࢉܭܕ‬ΑΔதॏ֩ߴεϐϯঢ়ଶͷ‫ه‬ड़ͱΧΠϥϧೋॏ߲όϯυʯ, ૉཻࢠɾ‫֩ࢠݪ‬ɾӉ஦ʮ‫͔ژ‬Βϙετ‫͚ͯ޲ʹژ‬ʯγϯϙδ΢Ϝ, ౦‫ژ‬, 2019 ೥ 1 ݄.
େ৓޾ޫ (Oral), ʮCNS ΠΦϯ‫ݯ‬ͷ‫ݱ‬ঢ়ʯ, ୈ 16 ճ AVF ߹ಉଧͪ߹Θͤ, 2018 ೥ 10 ݄ 30–31 ೔. ߴ࡚ྔࢠԠ༻‫ॴڀݚ‬.
খߴ߁র (Oral), ʮAVF ೖࣹ‫ي‬ಓղੳͷ‫ݱ‬ঢ়ʯ, ୈ 16 ճ AVF ߹ಉଧͪ߹Θͤ, ߴ࡚ྔࢠԠ༻‫ॴڀݚ‬, 2018 ೥ 10 ݄ 30–31 ೔.

Posters Presentations[International Conference etc.]
M. Dozono (Poster), “Proton- and deuteron-induced reactions on 107 Pd and 93 Zr at 20–30 MeV/nucleon,” The 10th international conference on Direct Reaction with Exotic Beams (DREB2018), Matsue, Japan, June 4–8, 2018.
J. W. Hwang (Poster), “Study on performance of the OEDO beamline,” The 10th international conference on Direct Reaction with Exotic
Beams (DREB2018), Matsue, Japan, June 4–8, 2018.
S. Shimoura (Poster), “Reduction and resource recycling of high-level liquid radioactive wastes through nuclear transmutation-Nuclear
Reaction Data of long-lived fission products,” Fifteenth NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation, Manchester Hall, Manchester, UK, September 30–October 3, 2018.
K. Kawata (Poster), “Production of isomer beam around 52 Fe nucleus via projectile fragmentation,” The 10th international conference on
Direct Reaction with Exotic Beams (DREB2018), Matsue, Japan, June 4–8, 2018.
S. Hayashi for the ALICE Collaboration (Poster), “Inclusive J/ψ measurement at mid-rapidity in p-Pb collisions with the ALICE detector,” Quark Matter 2018 (QM2018), Venice, Italy, May 13–19, 2018.
H. Shimizu (Poster), “Isomeric RIB Production of Aluminum-26,” 15th International Symposium on Nuclei in the Cosmos, LNGS,
Assergi, Italy, June 24–29, 2018.
N. Ozawa (Poster), “Development of a New Surface Ionizer for the FrEDM Experiment,” The 11th International Workshop on Fundamental
Physics Using Atoms, OIST, Okinawa, Japan, March 1–4, 2019.

[Domestic Conference]ԼӜ‫ ڗ‬ଞ (Poster), ʮPJ2-1 ௿଎ RI ϏʔϜ։ൃʯ, ImPACT ϓϩάϥϜʮ֩ม‫ʹ׵‬ΑΔߴϨϕϧ์ࣹੑഇ‫غ‬෺ͷେ෯ͳ௿‫ݮ‬ɾࢿ‫ݯ‬Խʯެ։੒Ռใࠂձ—৽ͨͳબ୒ࢶͷఏҊ, ະདྷʹ޲͚ͯ—, ඼઒ΠϯλʔγςΟϗʔϧ, ౦‫ژ‬, 2019 ೥ 3 ݄ 9 ೔.
T. Abe, “Alpha-cluster structure from no-core Monte Carlo shell model (poster),” The 1st R-CCS International Symposium on K and
Post-K: Simulation, Big Data and AI supporting Society 5.0, Kobe, Japan, February 2019.
Ѩ෦‫ڤ‬, “Alpha-cluster structure from no-core Monte Carlo shell modelʢϙελʔൃදʣ,” ৽ֶज़ྖҬʮྔࢠΫϥελʔͰಡΈղ͘෺࣭ͷ֊૚ߏ଄ʯ, ΩοΫΦϑγϯϙδ΢Ϝ, ౦޻େ, 2018 ೥ 11 ݄.

Awardsେ௡ल‫ڿ‬, ౻ాྰࢠ, দ࡚ఓࢢ࿠, ᓎҪതّ, ԼӜ‫ڗ‬, ਫ‫࢘ߒޱ‬, େҪ઒޺೭, খᖒਖ਼‫ج‬, ਔҪాߒೋ, ฏ੒ 30 ೥౓શࠃൃ໌දজʮ21ੈ‫໌ൃل‬৆ʯ, ʮ์ࣹੑഇ‫غ‬෺ͷॲཧํ๏ͷൃ໌ʯ, ʢಛ‫ڐ‬ୈ 6106892 ߸ʣ, 2018 ೥ 6 ݄.

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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, and additional MRTOF-MS setups are being fabricated and 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

KISS is an element-selective isotope separator, combining the use of a magnetic mass separator with in-gas-cell resonant laser
ionization. The gas cell, filled with argon gas at 75 kPa, is a central component of KISS, from which only the elements of interest are
extracted as an ion beam, and subsequently mass separated. In the cell, nuclei primarily produced by low-energy heavy-ion reactions
are stopped (thermalization and neutralization), transported by a buﬀer gas (gas flow of ∼ 75 kPa argon in the present case), and thenre-ionized by laser irradiation just before the exit. The gas cell was fabricated to eﬃciently collect the reaction products produced bymulti-nucleon transfer (MNT) reactions. For higher primary beam intensities and a higher extraction eﬃciency, a doughnut-shaped
gas cell with a rotating target wheel setup has been developed. The mass separated isotope beams are guided to a tape transport
setup where a low-background beta telescope counter is setup and surrounded by an array of germanium detectors consisting of four
super-clover germanium crystals. The system has successfully performed β-γ spectroscopy of isotopes of Pt, Ir and Os.
An important feature of KISS is the capability to perform laser spectroscopy by scanning the resonant ionization laser frequency.
The hyperfine structure constants of 196, 197, 198 Ir and 199 Pt have been measured at KISS. However, due to pressure broadening of theresonance line in the gas cell, the linewidths were as large as 12 GHz. To determine electromagnetic moments and isotope shifts withmuch higher precision, an “in-gas-jet” laser ionization method has been implemented at KISS. A high repetition rate, narrowband
laser radiation irradiates the atoms within the gas jet after the nozzle of the cell and an S-shaped radiofrequency quadrupole structure
guides resonantly ionized ions toward the mass separator. With this new setup, a narrow line width of 0.6 GHz has been achieved forthe hyperfine splitting spectrum of 194 Pt.
The multi-reflection time-of-flight mass spectrograph (MRTOF-MS) has been developed for direct mass measurements of shortlived heavy nuclei. After successful mass measurements of more than 80 nuclides, including short-lived (T 1/2 = 10 ms) isotopes ofRa and several isotopes of the trans-uranium elements Es and Md at GARIS-II in collaboration with the SLOWRI team and the Super
Heavy Element Synthesis team of RIKEN, multiple MRTOF setups are being installed at diﬀerent facilities of RIBF.
The first MRTOF was connected directly to the new GARIS-II in the E6 experimental room (after the ring cyclotron) in a manner
expected to yield a total eﬃciency of more than 10%. This device will used for precise mass measurements of Db isotopes producedin cold fusion reactions, as well for measurements of Mc and Nh isotopes produced in hot fusion reactions. In 2018, a short online
commissioning experiment was performed for testing the newly developed “alpha-ToF” detector which can correlate the time-of-flightsignal to alpha-decay signals. The test experiment with a Ra isotope showed that the background rate was highly reduced and, in
addition, the life-time of the isotope could be determined from the correlation data.
A mini-MRTOF with a so-called “gas-cell cooler buncher” setup has been installed at KISS and oﬄine commissioning is inprogress. Eﬃcient trapping of a 30 keV ion beam from KISS has been confirmed. A third-prototype SLOWRI gas catcher with a“gutter structure” RF-carpet has been developed for a new MRTOF setup, referred to as the ZD-MRTOF, for use at the beam dumpof the ZeroDegree spectrometer. This setup will be used for “symbiotic” experiments with other experimental groups who use the
ZeroDegree spectrometer to perform eﬃcient mass measurements in parallel to the other experiments.

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Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Members
Group Leader
Hiroari MIYATAKE
Researchers
Michiharu WADA
Yutaka WATANABE

Yoshikazu HIRAYAMAPeter SCHURY

Technical Staﬀ
Yutaka KAKIGUCHI

Michihiro OYAIZU

Visiting Researchers
Jun-young Moon (IBS)
Jin-hyung Park (IBS)

Hyun-suk CHOI (Seoul National University)

Student Trainees
Momo MUKAI (PhD. Student, Tsukuba Univ.)
Sota KIMURA (PhD. Student, Tsukuba Univ.)

Md MURAD AHMED (PhD. Student, Tsukuba Univ.)

Assistant
Machiko IZAWA

List of Publications & Presentations
Publications[Journal](Original Papers) *Subject to Peer Review
Y. Watanabe, Y. Hirayama, H. Miyatake, “KEK Isotope Separation System (KISS),” Nucl. Phys. News 28, 2–28 (2018).
M. Reponen, V. Sonnenschein, T. Sonoda, H. Tomita, M. Oohashi, D. Matsui, M. Wada, “Towards in-jet resonance ionization spectroscopy: An injection-locked Titanium: Sapphire laser system for PALIS-facility,” Nucl. Instrum. Methods Phys. Res. A 908, 236–243(2018). *P. Schury, Y. Ito, M. Rosenbusch, H. Miyatake, H. Wollnik, “Improving wide-band mass measurements in a multi-reflection time-of-flightmass spectrograph by usage of a concomitant measurement scheme,” Int. J. Mass Spectrom. 433, 40–46 (2018). *M. Wada, “௒ॏ‫ݩ‬ૉͷ࣭ྔଌఆ—ֵ৽త࣭ྔ෼ޫ‫ ث‬MRTOF-MS ʹΑΔ—,” Radiotisotopes 67, 299–308 (2018).
M. La Commara, M. Mazzocco, A. Boiano, C. Boiano, C. Manea, C. Parascandolo, D. Pierroutsakou, C. Signorini, E. Strano, D. Torresi,
H. Yamaguchi, D. Kahl, P. Di Meo, J. Grebosz, N. Imai, Y. Hirayama, H. Ishiyama, N. Iwasa, S. C. Jeong, H. M. Jia, Y. H. Kim,
S. Kimura, S. Kubono, C. J. Lin, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, Y. Sakaguchi, A. M. Sánchez-Benı́tez, F. Soramel,
T. Teranishi, Y. Wakabayashi, Y. X. Watanabe, L. Yang, Y. Y. Yang, “8 B + 208 Pb elastic scattering at Coulomb barrier energies,” J. Phys.
Conf. Ser. 966, 012010 (2018). *Y. Hirayama, Y. X. Watanabe, M. Mukai, M. Ahmed, S. C. Jeong, Y. Kakiguchi, S. Kimura, M. Oyaizu, J. H. Park, P. Schury, M. Wada,
H. Watanabe, H. Miyatake, “β- and γ-decay spectroscopy of 197, 198 Os,” Phy. Rev. C 98, 014321 (2018). *S. Kimura, Y. Ito, D. Kaji, P. Schury, M. Wada, H. Haba, T. Hashimoto, Y. Hirayama, M. MacCormick, H. Miyatake, J. Y. Moon,
K. Morimoto, M. Mukai, I. Muary, A. Ozawa, M. Rosenbusch, H. Schatz, A. Takamine, T. Tanaka, Y. X. Watanabe, H. Wollnik,“Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-offlight mass spectrograph,” Int. J. Mass Spectrom. 430, 134–142 (2018). *E. Strano, M. Mazzocco, A. Boiano, C. Boiano, M. La Commara, C. Manea, C. Parascandolo, D. Pierroutsakou, C. Signorini, D. Torresi,
H. Yamaguchi, D. Kahl, L. Acosta, P. Di Meo, J. P. Fernandez-Garcia, T. Glodariu, J. Grebosz, A. Guglielmetti, N. Imai, Y. Hirayama,
H. Ishiyama, N. Iwasa, S. C. Jeong, H. M. Jia, N. Keeley, Y. H. Kim, S. Kimura, S. Kubono, J. A. Lay, C. J. Lin, G. MarquinezDuran, I. Marte, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, A. Pakou, K. Rusek, Y. Sakaguchi, A. M. Sanchez-Benitez, T. Sava,
O. Sgouros, C. Stefanini, F. Soramel, V. Soukeras, E. Stiliaris, L. Stroe, T. Teranishi, N. Toniolo, Y. Wakabayashi, Y. X. Watanabe,
L. Yang, Y. Y. Yang, “7 Be and 8 B reaction dynamics at Coulomb barrier energies,” J. Phys. Conf. Ser. 184, 02015 (2018).
M. Rosenbusch, Y. Ito, P. Schury, M. Wada, D. Kaji, K. Morimoto, H. Haba, S. Kimura, H. Koura, M. MacCormick, H. Miyatake,J. Y. Moon, K. Morita, I. Murray, T. Niwase, A. Ozawa, M. Reponen, A. Takamine, T. Tanaka, H. Wollnik, “New mass anchor points
for neutron-deficient heavy nuclei from direct mass measurements of radium and actinium isotopes,” Phys. Rev. C 97, 064306 (2018).*
H. Miyatake, M. Wada, X. Y. Watanabe, Y. Hirayama, P. Schury, M. Ahmed, H. Ishiyama, S. C. Jeong, Y. Kakiguchi, S. Kimura,
J. Y. Moon, M. Mukai, M. Oyaizu, J. H. Park, “Present status of the KISS project,” AIP Conf. Proc. 1947, 020018 (2018).*
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. X. Watanabe, H. Wollnik, S. Yamaki, “First direct mass measurements of nuclides around Z = 100 with a multireflection Time-offlight mass spectrograph,” Phys. Rev. Lett. 120, 152501 (2018).*
M. Mukai, Y. Hirayama, Y. X. Watanabe, P. Schury, H. S. Jung, 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, H. Miyatake, “High-eﬃciency and low-background multi-segmented
proportional gas counter for be-ta-decay spectroscopy,” Nucl. Instrum. Methods Phys. Res. A 884, 1–10 (2018).*- 412 -

[Proceedings](Original Papers) *Subject to Peer Review
M. Mazzocco, 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, N. Imai, Y. Hirayama,
H. Ishiyama, N. Iwasa, S. C. Jeong, H. M. Jia, N. Keeley, Y. H. Kim, S. Kimura, S. Kubono, J. A. Lay, C. J. Lin, G. MarquinezⅥ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)
Duran, I. Martel, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, A. Pakou, K. Rusek, Y. Sakaguchi,
A. M. Sánchez-Benı́tez, T. Sava,
O. Sgouros, F. Soramel, V. Soukeras, E. Stiliaris, L. Stroe, T. Teranishi, N. Toniolo, Y. Wakabayashi, Y. X. Watanabe, L. Yang,
Y. Y. Yang, “8 B + 208 Pb elastic scattering at Coulomb barrier energies,” J. Phys. Conf. Ser. 1078, 012013 (2018).*
T. Sonoda, H. Iimura, M. Reponen, M. Wada, I. Katayama, V. Sonnenschein, T. Takamatsu, H. Tomita, T. M. Kojima, “The laser andoptical system for the RIBF-PALIS experiment,” Nucl. Instrum. Methods Phys. Res. A 877, 118–123 (2018) .*Oral Presentations[Proceedings][International Conference etc.](Original
Papers)*Subject to Peer
M. Wada, “Massmeasurementswith Review
MRTO at RIKEN RIBF,” NUSTAR Week 2018, Milan, Italy, September 27, 2018.
M.
Mazzocco,
A.
Boiano,C.
Boiano,M. La
Commara,C. Manea,
C. Parascandolo,
D. Paris,
Pierroutsakou,
C. Signorini,
E. 2018.
Strano, D. Torresi,
M. Wada, “Mass measurements of heavy
elements
at GARIS,”SSNET18
Conference,France, November
5–11,
H. Yamaguchi, D. Kahl, L. Acosta, P. Di Meo, J. P. Fernandez-Garcia, T. Glodariu, J. Grebosz, A. Guglielmetti, N. Imai, Y. Hirayama,
M.H.Wada,“MRTOF
mass S.
spectrographs
RIKEN— toward
comprehensive
measurementsof >1000
nuclidesincludingIshiyama,
N. Iwasa,
C. Jeong, H.atM.
Jia, N.RIBF
Keeley,Y. H. Kim,
S. Kimura,mass
S. Kubono,J. A. Lay,
C. J. Lin,G. Marquinezsuperheavy
nuclides
—,”
13th
Int.
Conf.
on
Nucleus
Nucleus
Collisions(NN2018),
Omiya,
Japan,
December
4,
2018.
Duran, I. Martel, H. Miyatake, M. Mukai, T. Nakao, M. Nicoletto, A. Pakou, K. Rusek, Y. Sakaguchi, A. M. Sánchez-Benı́tez, T. Sava,
P. O.
Schury,“KISS
and MRTOF
project of E.
KEK,”
10thL.China
Joint Nuclear
PhysicsY.Symposium(CJNP2018),
Huizhou,
Sgouros,
F. Soramel,
V. Soukeras,
Stiliaris,
Stroe,Japan
T. Teranishi,
N. Toniolo,
Wakabayashi,
Y. X. Watanabe,
L. China,
Yang,
November2018.
Pb elastic scattering at Coulomb barrier energies,” J. Phys. Conf. Ser. 1078, 012013 (2018).*
Y.
Y. Yang,18–23,“8 B + 208

Oral Presentations[International Conference etc.]
M. Wada, “Mass measurements with MRTO at RIKEN RIBF,” NUSTAR Week 2018, Milan, Italy, September 27, 2018.
M. Wada, “Mass measurements of heavy elements at GARIS,” SSNET18 Conference, Paris, France, November 5–11, 2018.
>1000 nuclides including
M. Wada, “MRTOF mass spectrographs at RIKEN RIBF — toward comprehensive mass measurements of >1000
superheavy nuclides —,” 13th Int. Conf. on Nucleus Nucleus Collisions (NN2018), Omiya, Japan, December 4, 2018.
P. Schury, “KISS and MRTOF project of KEK,” 10th China Japan Joint Nuclear Physics Symposium (CJNP2018), Huizhou, China,
November 18–23, 2018.
Y. Hirayama, “Nuclear spectroscopy of r-process nuclei using KEK isotope separation system,” International Conference on Electromagnetic
Isotope Separators and Related Topics (EMIS2018), CERN Geneva, Switzerland, September 16–21, 2018.
M. Mukai, “Development of a multi-segmanted proportional gas counter for beta-decay sepectroscopy at KISS,” International Conference
on Electromagnetic Isotope Separators and Related Topics (EMIS2018), CERN Geneva, Switzerland, September 16–21, 2018.
Y. X. Watanabe, “Production of neutron-rich nuclei by multinucleon transfer reactions at KISS project,” IX Int. Symp. On Exotic Nuclei(EXON2018), Petrozavodsk, Russia, September 10–15, 2018.

[Domestic Conference]
H. Miyatake, ʮr-աఔͷୈࡾϐʔΫͱऴᖼྖҬ–KEK-WNSC ͷΞϓϩʔνʯ, ॏྗ೾‫؍‬ଌ࣌୅ͷ r ϓϩηεͱෆ҆ఆ֩‫ڀݚ‬ձ, 2018
೥ 6 ݄ 20–22 ೔.
H. Miyatake, “RNB project on the astrophysical element synthesis,” TGSW2018, ஜ೾େֶ, 2018 ೥ 9 ݄ 21 ೔.
M. Wada, ʮ֩σʔλͱॏ‫ݩ‬ૉ߹੒Λத৺ͱ͢ΔӉ஦֩෺ཧ‫ڀݚ‬ձ, ࡳຈ, 2019 ೥ 3 ݄ 6–8 ೔.
Y. Hirayama, “Nuclear spectroscopy of r-process nuclei in the vicinity of N = 126 at KISS,” ೔ຊ෺ཧֶձ೥࣍େձ Joint Symposium
on Nuclear structure studies through the magic numbers, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14–17 ೔.
Y. X. Watanabe, “Production of neutron-rich nuclei by multinucleon transfer reactions at KISS project,” IX Int. Symp. On Exotic Nuclei(EXON2018), Petrozavodsk, Russia, September 10–15, 2018.

[Domestic Conference]
H. Miyatake, ʮr-աఔͷୈࡾϐʔΫͱऴᖼྖҬ–KEK-WNSC ͷΞϓϩʔνʯ, ॏྗ೾‫؍‬ଌ࣌୅ͷ r ϓϩηεͱෆ҆ఆ֩‫ڀݚ‬ձ, 2018
೥ 6 ݄ 20–22 ೔.
H. Miyatake, “RNB project on the astrophysical element synthesis,” TGSW2018, ஜ೾େֶ, 2018 ೥ 9 ݄ 21 ೔.
M. Wada, ʮ֩σʔλͱॏ‫ݩ‬ૉ߹੒Λத৺ͱ͢ΔӉ஦֩෺ཧ‫ڀݚ‬ձ, ࡳຈ, 2019 ೥ 3 ݄ 6–8 ೔.
Y. Hirayama, “Nuclear spectroscopy of r-process nuclei in the vicinity of N = 126 at KISS,” ೔ຊ෺ཧֶձ೥࣍େձ Joint Symposium
on Nuclear structure studies through the magic numbers, ‫۝‬भେֶ, ෱Ԭ, 2019 ೥ 3 ݄ 14–17 ೔.

- 413 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Events (April 2018 — March 2019)
RNC
Apr. 21

Wako Open Campus

Jun. 12The 24th RBRC Management Steering Committee (MSC)

Jun. 29

The 8th Industrial Program Advisory Committee (In-PAC)

Jul. 20

The 16th Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)

Jul.24–Aug.3

Nishina School

Nov.29–Dec.3

The 19th Program Advisory Committee for Nuclear Physics Experiments at RI Beam Factory (NP-PAC)Jan

The 17th Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)P-PAC)

Jan. 11

Interim Review of the Chief Scientist, Tomohiro UESAKA

CNS
Aug. 22–28

17th CNS International Summer School CNSSS18
https://indico2.cns.s.u-tokyo.ac.jp/event/30/

KEK
Sept. 42018 SSRI-PNS Collaboration meeting. http://research.kek.jp/group/wnsc/workshop/2018_SSRI-PNS_201809/- 414 -

Ⅵ. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 52 (2019)

Press Releases (April 2018−March 2019)
RNC
Apr. 13Spectroscopy of pionic atoms in 122Sn(d,3He) reaction and angular dependence of theformation cross sections

T. Nishi, Spin isospin Laboratory
K. Itahashi, Meson Science Laboratory

May. 24

Most Strange Dibaryon from Lattice QCD

S. Gongyo, T. Doi, Quantum Hadron Physics
Laboratory

May. 29

Termination of Electron Acceleration in Thundercloud by Intra/Inter-cloud Discharge

Y. Wada, High Energy Astrophysics
Laboratory

May. 31

A per-cent-level determination of the nucleon axial coupling from quantum
chromodynamics

E. Rinaldi, Computing Group, RIKEN BNL
Research Center

Jul. 10

Magic Nature of Neutrons in 54Ca: First Mass Measurements of 55-57Ca

T. Uesaka, Spin isospin Laboratory

Jul. 12

Discovery of 60Ca and Implications For the Stability of 70Ca

O. B. Tarasov, D. Ahn, N. Suzuki, BigRIPS
Team

Aug. 3Development of Ferromagnetic Fluctuations in Heavily Overdoped (Bi, Pb)2Sr2CuO6＋δ
I. Watanabe, Meson Science Laboratory
Copper Oxides

Aug. 11

Novel shape evolution in Sn isotopes from magic numbers 50 to 82

T. Otsuka, Nuclear Spectroscopy Laboratory

Oct. 2

Characterization of the shape-staggering effect in mercury nuclei

T. Otsuka, Nuclear Spectroscopy Laboratory

Oct. 19

Extraction of the Landau-Migdal Parameter from the Gamow-Teller Giant Resonance in
132Sn

M. Sasano, T. Uesaka, Spin isospin
Laboratory

Dec. 11Creation of quark-gluon plasma droplets with three distinct geometry

Y. Akiba, Experimental Group, RIKEN BNL
Research Center

Jan. 30

Interplay between nuclear shell evolution and shape deformation revealed by themagnetic moment of 75Cu

Y. Ichikawa, H. Ueno, Nuclear Spectroscopy
Laboratory

Feb. 28First spectroscopy of the Near Drip-line Nucleus 40Mg

P. Doornenbal, H. Sakurai, Radioactive
Isotope Physics Laboratory

希少原子核の高効率・高分解能質量測定による新しい魔法数 34 の確証

道正新一郎、小林幹、下浦亨、他

CNS
Jul. 10- 415 -

VII. LIST OF PREPRINTS

Ⅶ. LIST OF PREPRINTS

RIKEN Accel. Prog. Rep. 52 (2019)

List of Preprints (April 2018 ― March 2019)
RIKEN NC-NP
188

Nascent fragment shell effects on the nuclear fission processes in semiclassical periodic orbit
theoryK. Arita et al.

189

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

B. Deya et al.

190

Interplay between nuclear shell evolution and shape deformation revealed by the magnetic
moment of 75Cu

Y. Ichikawa et al.

RIKEN NC- AC
Not Applicable

RIKEN MP
Not Applicable

RIKEN QHP
373

Many Fermi polarons at nonzero temperature

H. Tajima, S. Uchino

374

Quantitative analysis of tensor effects in the relativistic Hartree-Fock theory

Z. Wang et al.

375

Side-jump induced spin-orbit interaction of chiral fluids from kinetic theory

D. Yang376

High precision nuclear mass predictions towards a hundred kilo-electron-volt accuracy

Z. Niu et al.

377

Non-equilibrium quantum transport of chiral fluids from kinetic theory

Y. Hidaka et al.

378

Asymptotic behavior of Nambu-Bethe-Salpeter wave functions for scalar systems with a boundstate

S. Gongyo, S. Aoki

379
380
381
382
383
384

Holographic 𝐽𝐽𝐽𝐽𝐽 production near threshold and the proton mass problem

Y. Hatta, D. Yang

Diffusive Nambu-Goldstone modes in quantum time crystals

T. Hayata, Y. Hidaka

QCD sum rule for open strange meson K ±1 in nuclear matter

T. Song et al.

N Ω dibaryon from lattice QCD near the physical point

T. Iritani et al.

Coulomb exchange functional with generalized gradient approximation for self-consistent Skyrme
T. Naito et al.
Hartree-Fock calculations

Linear confinement and stress-energy tensor around static quark and anti-quark pair —Latticesimulation with Yang-Mills gradient flow—

R. Yanagihara et al.

385

Thermodynamics in the quenched QCD — EMT with NNLO coefficients in gradient flow formalism T. Iritani et al.

386

HAL QCD method and Nucleon-Omega interaction with physical quark masses

387

Functional-renormalization-group aided density-functional analysis for the correlation energy ofT. Yokota, T. Naito
the two-dimensional homogeneous electron gas

388
389
390
391

T. Iritani (HAL QCD Collaboration)

Measurement of time-dependent CP Asymmetries in B0 → K 0s ηγ decays

H. Nakano (Belle Collaboration)

Observation of an excited Ω– baryon

J. Yelton (Belle Collaboration)(�)–

Search for Υ(1𝑆𝑆𝑆 𝑆𝑆𝑆) → Z c+ Z c(�)–and 𝑒𝑒 � 𝑒𝑒 � → Z c+ Z c

at √s = 10.52, 10.58, and 10.867 GeV

Observation of Υ(4𝑆𝑆) → 𝜂𝜂� Υ(1𝑆𝑆𝑆

S. Jia (Belle Collaboration)

E. Guido (Belle Collaboration)- 417 -

Ⅶ. LIST OF PREPRINTS

RIKEN Accel. Prog. Rep. 52 (2019)

392
393
394
395
396
397
398
399

Inclusive study of bottomonium production in association with an η meson in e +e – annihilations
near Υ(5𝑆𝑆)
Search for the lepton-flavor-violating decay 𝐵𝐵� → 𝐾𝐾 �� 𝜇𝜇 ± 𝑒𝑒 ∓Measurement of 𝜂𝜂� (1𝑆𝑆), 𝜂𝜂� (2𝑆𝑆𝑆 and non-resonant 𝜂𝜂� 𝜋𝜋 � 𝜋𝜋 � production via two-photon collisions

U. Tamponi (Belle Collaboration)
S. Sandilya (Belle Collaboration)
Q. N. Xu (Belle Collaboration)� � Λ�� consistent with a charged Ξ� (2930)� , and updated measurement
Evidence of a structure in 𝐾𝐾
Y. B. Li (Belle Collaboration)� � Λ�� Λ�� at Belleof 𝐵𝐵�� → 𝐾𝐾
Observation of 𝑒𝑒 � 𝑒𝑒 � → 𝜋𝜋 � 𝜋𝜋 � 𝜋𝜋 � 𝜒𝜒�1, 2 (1𝑃𝑃𝑃 and search for 𝑒𝑒 � 𝑒𝑒 � → 𝜙𝜙𝜙𝜙�1, 2 (1𝑃𝑃𝑃 at √𝑠𝑠 = 10.96–11.05
GeV
Observation of Υ(2𝑆𝑆) → 𝛾𝛾𝛾𝛾� (1𝑆𝑆𝑆 decay

J. H. Yin (Belle Collaboration)
B. G. Fulsom (Belle Collaboration)

Observation of 𝑒𝑒 � 𝑒𝑒 � → 𝛾𝛾𝛾𝛾c� and search for 𝑒𝑒 � 𝑒𝑒 � → 𝛾𝛾𝛾𝛾c� , 𝛾𝛾𝛾𝛾c2 , and 𝛾𝛾𝛾𝛾c at √𝑠𝑠 near 10.6 GeV at Belle S. Jia (Belle Collaboration)
Measurement of the branching fraction and time-dependent CP asymmetry for 𝐵𝐵� → 𝐽𝐽𝐽𝐽𝐽𝐽𝐽𝐽 �
decaysB. Pal (Belle Collaboration)

Consistency between Luescher's finite volume method and HAL QCD method for two-baryon
systems in lattice QCD

T. Iritani et al.

401

Multi-body correlations in SU(3) Fermi gases

H. Tajima, P. Naidon

402

Thermal crossover, transition, and coexistence in Fermi polaronic spectroscopies

H. Tajima, S. Uchino

403

Improvement of functionals in density functional theory by the inverse Kohn-Sham method and
D. Ohashi et al.
density functional perturbation theory

404

Distribution of solutions of the fastest apparent convergence condition in optimized perturbation
S. Tsutsui, T. M. Doi
theory and its relation to anti-Stokes lines

405

Heavy quark spin multiplet structure of Pc -like pentaquark as P-wave hadronic molecular state

406

Enhanced critical temperature, pairing fluctuation effects, and BCS-BEC crossover in a two-band
H. Tajima et al.
Fermi gas407

Anomaly-induced transport phenomena from the imaginary-time formalism

M. Hongo, Y. Hidaka

408

Chiral kinetic theory for massive fermions

K. Hattori et al.

409

Topological order in the color-flavor locked phase of (3+1)-dimensional U(N) gauge-Higgs system Y. Hidaka et al.

410

Universal crossover in interacting fermions within the low-energy expansion

400

Y. Shimizu et al.

H. Tajima

CNS-REP97

CNS Annual Report 2017

T. Gunji, Y. Kishi

Nishina Center Preprint server (not including Partner Institution) can be found at
http://nishina-preprints.riken.jp/- 418 -

VIII. LIST OF SYMPOSIA,
WORKSHOPS & SEMINARS

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 52 (2019)

List of Symposia & Workshops (April 2018―March 2019)
RNC
1

26th International Workshop on Deep Inelastic Scattering and Related Topics (DIS2018)

Convention Hall of Kobe
University

Apr. 16–20

2

Workshop on r-Process and Unstable Nuclei in Multi-Messenger Astronomy（重⼒波観測時代の r プロセスと不安定核）

RIBF Conf. Hall, RIKEN
Wako Campus

Jun. 20–22

3

Tesla Technology Collaboration Meeting 2018 (TTC2018)

RIKEN Wako Campus

Jun. 26–29

4

Nishina School 2018

RIBF Conf. Hall, RIKEN
Wako Campus

Jul. 24–Aug. 45

8th International Conference on Quarks and Nuclear Physics (QNP2018)

Tsukuba International
Congress Center

Nov. 13–17

6

13th International Conference on Nucleus-Nucleus Collision (NN2018)

Omiya Sonic City

Dec. 4–8

7

The public symposium “Significance of Basic Science Research and its Impact on Society(in physics)”

Auditorium at Science
Council of Japan

Dec.17

8

The 1st Symposium on Heavy and Cluster Ions Mutagenesis of Microorganisms
for finding Solutions to The Issue of Hyper-productivity, Energy and Environment

University of Tsukuba

Jan. 29

9

Integrated Innovation
The 2nd RIBF “Hodan-kai” Meeting: Future of Exotic Nuclear Physics（第２回 RIBF 若⼿放談会：
Building, RIKEN Kobe
エキゾチック核物理の将来）
CampusFeb. 18–20

10

The International Year of the Periodic Table of Chemical Elements and activities supporting the Auditorium at Science
Council of Japan
Year（国際周期表年 2019 記念シンポジウム「周期表が拓く科学と技術国際周期表年を迎えて」）

Feb. 23

CNS
1

CNS

International OEDO Workshop

Jun. 11

List of Seminars (April 2018―March 2019)
Nuclear Physics Monthly Colloquium
1

Masaaki Hashimoto(Kyushu U.)

Stellar evolution and nucleosynthesis in massive stars
https://indico2.riken.jp/event/2881/

Oct. 3

RIBF Nuclear Physics Seminar
1

Itaru Nakagawa(RIKEN)

Surprising forward neutron asymmetries observed in polarized proton + nucleus collision
at RHIC
https://indico2.riken.jp/event/2754/

Apr. 10

2

Takahiro Kawabata(Kyoto U.)

Direct measurement of the 7Be(n, α)4He reaction cross section for the cosmological Li problem
https://indico2.riken.jp/event/2753/

Apr. 17

3

Takehiko Saito(GSI)

Hypernuclear spectroscopy with heavy ion beams: past, present and future
https://indico2.riken.jp/event/2772/

May 10- 419 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 52 (2019)4

Koji Yoshimura(RIIS, Okayama U.)

Hunting for mysterious ultra-low energy isomer of Thorium-229 –to realize ultimate "nuclear
clock”–
https://indico2.riken.jp/event/2773/

May 22

5

Newcomers to Nishina
Center in 2018

Newcomers’ seminarhttps://indico2.riken.jp/event/2774/

May 296Hironobu Ishiyama(RNC)

SLOWRI and related topics
https://indico2.riken.jp/event/2788/

Jul. 37

Noritaka Shimizu(U. Tokyo)

Double Gamow Teller transition and its relation to neutrinoless double beta decay matrix element
Jul. 10
https://indico2.riken.jp/event/2789/

8

Michiharu Wada(KEK)

The multi-reflection time-of-flight mass spectrographs at RIBF: Present and future
https://indico2.riken.jp/event/2825/

Jul. 319Karlheinz Langanke(GSI)

Progress and scientific perspectives for the Facility of Antiproton
https://indico2.riken.jp/event/2844/

Sep. 21

10

Shinya Gongyo(RIKEN)

Dibaryon candidates in decuplet baryons from lattice QCD
https://indico2.riken.jp/event/2877/

Oct. 2

11

Sachio Komamiya/Hitoshi Hayano(Waseda U./KEK)

Introduction of ILC ~The physics, the accelerator, and the project status
https://indico2.riken.jp/event/2878/

Oct. 12

12

Hiroyuki Sagawa(U. Aizu)

The nuclear symmetry energy and the breaking of the isospin symmetry: how do they reconcile
with each other?
Nov. 20https://indico2.riken.jp/event/2906/

13

Shin'ichiro Michimasa(CNS)

First mass measurements of 55−57Ca
https://indico2.riken.jp/event/2945/

Dec. 11

14

Hidetoshi Yamaguchi(CNS)

Study on cluster states in unstable nuclei with alpha-resonant scatteringhttps://indico2.riken.jp/event/2954/

Jan. 815

Masaki Sasano(RNC)

Gamow-Teller giant resonance in 132Sn
https://indico2.riken.jp/event/2973/

Jan. 22

16

Yuichi Ichikawa(RNC)

Interplay between nuclear shell evolution and shape deformation revealedby the magnetic moment of 75CuFeb. 26

17

Fedor Šimkovic(Comenius U./ BLTP)

Massive neutrinos in nuclear processes
https://indico2.riken.jp/event/2992/

Mar. 518

Ali Al-adili(Uppsala U.)

Angular momenta in atomic nuclei – investigated by the population of nuclear isomers
https://indico2.riken.jp/event/3003/

Mar. 819

Shinya Wanajo(NAOJ)

R-process and kilonova
https://indico2.riken.jp/event/3004/

Mar. 1220

Epelbaum Evgeny(Ruhr-U.)

Chiral EFT and the three-nucleon force problem
https://indico2.riken.jp/event/3005/

Mar. 25

21

Ushasi Datta(SINP)A journey from light neutron rich-nuclei to heavier nuclei near proton-drip line
https://indico2.riken.jp/event/3007/

Mar. 29

22

Timo Dickel(JLU/GSI)

Experiments with thermalized RIB at the FRS
https://indico2.riken.jp/event/3008/

Mar. 29

Seminar by Each Laboratory
Nuclear Science and Transmutation Research Division
1

Susumu Inoue(iTHEMS)The dawning of electroweak astronomy: interpreting electromagnetic +neutrino observations of
Sep. 27
blazars- 420 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 52 (2019)2

Shin Watanabe(ISAS, JAXA)

Si/CdTe 半導体コンプトンカメラの開発研究と⾼感度 MeV ガンマ線観測実現に向けた展望

Sep. 27

3

Minoru Tanaka(Osaka U.)

同位体シフトで探る素粒⼦の新しい相互作⽤

Jan. 24

4

Takaya Nozawa(NAOJ)

Formation of dust and molecules in supernovae

Feb. 6

Subnuclear System Research Division1

Matthias Berwein(RIKEN)QHP Seminar:
Applications of effective field theories for heavy quarks

May 7

2

Yoshiko Kanada-En'yo(Kyoto U.)

SNP Seminar:
Isoscalar monopole and dipole excitations in light nuclei

May 173

Kazuya Mameda(Fudan U.)

QHP Seminar:
Rotational effects on quantum field theory for quark and hadron

May 22

4Hiromichi Nishimura(RIKEN, RBRC)QHP Seminar:On thermal effective potential of pure gauge theory at large N

May 30

5

Yuki Fujimoto(U. Tokyo)

QHP Seminar:
Methodology study of machine learning for the neutron star equation of state

Jun. 18

6

Yusuke Namekawa(U. Tsukuba)

SNP Seminar:
Successful prediction to charmed single hadrons and attempt on two-hadron by lattice QCD

Jun. 18

7

Nodoka Yamanaka(IPN Orsay))

SNP Seminar:
The AFTER project, and the gluon and charm content of the deuteronJun. 20

8

Daisuke Kadoh(Keio U.)QHP Seminar:
Tensor network approach to lattice field theory

Jun. 25

9

Noriyuki Sogabe(Keio U.)QHP Seminar:
Does the chiral magnetic effect affect the dynamic critical phenomena in QCD?

Jul. 2

10

Yuki Kamiya(Kyoto U.)

SNP Seminar:
Model-independent determination of structure of exotic hadrons with the scattering amplitude

Jul. 25

11

Kazuo Fujikawa(RIKEN, iTHEMS)QHP Seminar:
Chiral anomaly and Berry's phase

Sep. 10

12

Shunsuke Yabunaka(Kyoto U.)

QHP Seminar:
Surprises in the O(N) models: nonperturbative fixed points, large N limit and multi-criticality

Sep. 21

13

Takahiro Ohgoe(U. Tokyo)

QHP Seminar:
Resummation of diagrammatic series with zero convergence radius for the unitary Fermi gas

Oct. 1

14

Michele Viviani(INFN Pisa & U. of Pisa)

SNP Seminar:
Theoretical study of three and four neutron resonances

Oct. 1115

Takeru Yokota(Kyoto U.)

QHP Seminar:
Functional renormalization group-aided density-functional theory–application to one-dimensional nuclear matter and two-dimensional electron gas–

Oct. 15

16

Akihiko Monnai(KEK)

QHP Seminar:
The quark-gluon plasma fluid at finite density

Nov. 517

Huseyin Bahtiyar
SNP Seminar:(Mimar Sinan Fine Arts U. ) Radiative transitions of singly – and doubly-charmed baryons in lattice QCD

Nov. 20

18

GuangJuan Wang
(Peking U.)

Dec. 3

SNP Seminar:
The strong decay patterns of Zc and Zb states in the relativized quark model- 421 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 52 (2019)19

Akio Tomiya(RIKEN-BNL)QHP Seminar:
Deep Learning and Holographic QCD

Dec. 1020Hiromasa Takaura(Kyushu U.)

QHP Seminar:
Renormalon and gluon condensate

Dec. 1721

Masahiro Nozaki(RIKEN)QHP Seminar:
Signature of quantum chaos in operator entanglement in 2d CFTs

Jan. 21

22

Toshiaki Fujimori(Keio U.)QHP Seminar:
Bions and resurgence in ℂP N modelJan. 28

23

René Meyer(U. Würzburg)

QHP Seminar:
Hydrodynamics & black holes in anti de sitter space-timeMar. 25

24

Andreas Schmitt(U. Southampton)

Nuclear Theory/RIKEN Seminar:
Dense nuclear and quark matter from holography

Apr. 625

Bernd-Jochen Schaefer(U. Giessen)

Nuclear Theory/RIKEN Seminar:
Exploring the QCD phase structure with functional methods

Apr. 27

26

Peter Love
(Tufts)HET/RIKEN Lunch Seminar:
Quantum simulation from quantum chemistry to quantum chromodynamics

May 1027

HET/RIKEN
Lunch Discussions

HET/RIKEN Lunch Discussions:
Localized 4-sigma and 5-sigma dijet mass excesses in ALEPH LEP2 four-jet events

May 1128

Stanley Brodsky(SLAC, Stanford U.)

Joint Nuclear Theory/RIKEN/CFNS Seminar:
Novel QCD physics at an Electron-Ion Collider

May 2529

Vladimir Skokov(BNL)

Nuclear Theory/RIKEN Seminar:
Liouville action, high multiplicity tail and shape of proton

Jun. 130

Rasmus Larsen(BNL)

RIKEN Lunch Seminar:
Topological structures in finite temperature QCD

Jul. 1231

Matt Luzum(U. Sao Paulo)

Nuclear Theory/RIKEN Seminar:
Confronting hydrodynamic predictions with Xe-Xe heavy-ion collision data

Jul. 1332

Alessandro Roggero(U. Washington)

RIKEN Lunch Seminar/Special Nuclear Theory Seminar:
Neutrino scattering on quantum computers

Jul. 19

33

Zhongbo Kang
(UCLA)

Nuclear Theory/RIKEN Seminar:
Jets as a probe of transverse spin physics

Jul. 27

34

Shigemi Ohta
(IPNS, KEK)

RIKEN Lunch Seminar:
Nucleon isovector axial charge in 2+1-flavor domain-wall QCD with physical mass

Aug. 235

Masanori Hanada(YITP)RIKEN Lunch Seminar:
Universality in classical and quantum chaosAug. 1636

Andreas Weichselbaum(BNL)

RIKEN Lunch Seminar:
Non-abelian symmetries and applications in tensor networks

Aug. 23

37

Joaquin Drut
(UNC)

Special Nuclear Theory/RIKEN Lunch Seminar:
Signal-to-noise issues in non-relativistic quantum matter: from entanglement tothermodynamics

Aug. 30

38

Ivan Horvath(U. Kentucky)

RIKEN/NT & Quantum Computing Seminar:
Quantum uncertainty and quantum computation

Sep. 6

39

Julien Baglio(Tuebingen U.)

Joint BNL/RIKEN HET Seminar:
Higgs pair production via gluon fusion at NLO QCD

Sep. 1240

Yuta Kikuchi(RBRC)RIKEN Lunch Seminar:
Giant photocurrent in asymmetric Weyl semimetals from the helical magnetic effect

Sep. 13

41

Ilkka Helenius(U. Tubingen)Nuclear Theory/RIKEN Seminar:
Status of Pythia 8 for an Electron-Ion Collider

Sep. 21- 422 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 52 (2019)42

Jordy De Vries(UMass Amherst)

Nuclear Theory/RIKEN Seminar:
Neutrinoless double beta decay in effective field theory

Sep. 28

43

Shaouly Bar-Shalom(Technion)

HET/RIKEN Seminar:
A universally enhanced light-quarks Yukawa couplings paradigm

Oct. 10

44

Nikhil Karthik(BNL)

RIKEN Lunch Seminar:
Valence parton distribution function of pion using lattice

Oct. 18

45

Aleksas Mazeliauskas(U. Heidelberg)

Nuclear Theory/RIKEN Seminar:
Studying out-of-equilibrium Quark-Gluon Plasma with QCD kinetic theory

Oct. 19

46

Kiminad Mamo
(Stony Brook U.)

RIKEN Lunch Seminar:
DIS on ""Nuclei"" using holography

Nov. 1

47

Alfred Mueller(Columbia U.)

Nuclear Theory / RIKEN Seminar:
Diffractive electron-nucleus scattering and ancestry in branching random walks

Nov. 248

Ajit Srivastava(IOPB)

Nuclear Theory / RIKEN Seminar:
Towards laboratory detection of superfluid phases of QCD

Nov. 949

Renaud Boussarie(BNL)

RIKEN Lunch Seminar:
Exclusive ρ meson production in eA collisions: collinear factorization and the CGC

Nov. 1550

Dimitra Karabali(CUNY)

Nuclear Theory / RIKEN:
Casimir effect in Yang-Mills theory

Nov. 16

51

Juan Rojo(VU U.)

Nuclear Theory / RIKEN Seminar:
Novel probes of small-x QCD

Nov. 30

52

Mario Mitter(BNL)

RIKEN Lunch Seminar:
On QCD and its phase diagram from a functional RG perspective

Dec. 653

Micheal Wagman(MIT)

NT/RIKEN Seminar:
Lattice QCD input for fundamental symmetry tests

Dec. 14

54

Alba Soto Ontoso(BNL)

RIKEN Lunch Seminar:
A novel background subtraction method for jet studies in heavy ion collisions

Jan. 1055

Jun-sik Yoo(Stony Brook U.)

RIKEN Lunch Seminar:
Proton decay matrix elements on latticeJan. 1756

Andrey Sadofyev(Los Alamos National Lab)

Nuclear Theory / RIKEN Seminar:
Chiral vortical effect for an arbitrary spinJan. 18

57

Xiaojun Yao(Duke U.)RIKEN Lunch Seminar:
Quarkonium production in heavy ion collisions: open quantum system, effective field theory
and transport equations

Jan. 24

58

Paolo Glorioso(U. Chicago)

Nuclear Theory / RIKEN Seminar:
Effective field theory of hydrodynamics

Jan. 25

59

Jasmine Brewer(MIT)

RIKEN Lunch Seminar:
Sorting out jet quenching in heavy-ion collisions

Jan. 3160

Juan M. Torres-Rincon(Stony Brook U.)

RIKEN Lunch Seminar:
Modification of the nucleon-nucleon potential and nuclear correlations due to the QCD critical Feb. 7
point

61

Eden Figueroa(Stony Brook U.)

NT / RIKEN Seminar:
Realizing relativistic dynamics with slow light polaritons at room temperature

Feb. 862

Sahal Kaushik(Stony Brook U.)

RIKEN Lunch Seminar:
Chiral photocurrents and terahertz emission in Dirac and Weyl materials

Feb. 1463

Jacobus Verbaarschot(Stony Brook U.)

NT / RIKEN Seminar:
Quantum chaos, wormholes and the Sachdev-Ye-Kitaev modelFeb. 2264

Ana-Maria Raclariu(Harvard U.)

Joint NT/RIKEN/CFNS Seminar:
Measuring color memory in a color glass condensate

Feb. 28- 423 -

Ⅷ. LIST OF SYMPOSIA, WORKSHOPS & SEMINARS

RIKEN Accel. Prog. Rep. 52 (2019)

65

Zohar Komargodski(Stony Brook U.)

NT/RIKEN Seminar:
Baryons as Quantum Hall DropletsMar. 1566

Hosted by Sally Dawson

High Energy / Nuclear Theory / RIKEN Seminars:
Lattice Workshop for US-Japan Intensity Frontier Incubation

Mar. 25–27

67

Jamal Jalilian-Marian(CUNY)

NT/RIKEN Seminar:
Mar. 29
Toward a unified description of both low and high pT particle production in high energy collisions

CNS
1

Marco Mazzocco(U. of Padova / INFN)

Reaction dynamics studies with light weakly-bound radioactive ion beams at near-barrierenergies
https://indico2.riken.jp/event/2970/

Dec. 10

2

Christian Smorra(CERN)

High-precision measurements of the antiproton’s fundamental properties
https://indico2.riken.jp/event/2969/

Dec. 123

Afanasjev Anatoli(Mississipi State U.)

Covariant density functional theoretical studies across the nuclear landscapehttps://indico2.riken.jp/event/2968/

Dec. 13

4

Ken'ichi Nakano(Tokyo Tech)

Measurement of flavor asymmetry of light antiquarks in proton via Drell-Yan process at Fermilab
SeaQuest
Jan. 29https://indico2.riken.jp/event/2967/

5

Fedor Šimkovic(Comenius U./BLTP JINR)

Massive neutrinos in nuclear processes
https://indico2.riken.jp/event/2992/

Mar. 5

Advancing Penning trap mass spectrometry of rare isotopes at the LEBIT facility

Jul. 2

KEK WNSC
1

Ryan Ringle(Michigan State U.)- 424 -

理化学研究所

埼玉県 和光市 広沢
RIKEN 2019-045