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

56

RIKEN Accelerator Progress Report
vol.

56

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 2022 Vol. 56
This is an unabridged version of the 56th 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
Hiroyoshi Sakurai
Editorial Board
H. Haba (Editor-in-Chief), D. Suzuki, K. Tateishi, A. Kohama, M. Kimura, E. Hiyama, T. Sumikama, R. Seidl, T. Doi,
Y. Akiba, T. Tamagawa, K. Takahashi, K. Ozeki, Y. Higurashi, K. Morimoto, M. Watanabe, H. Sato, T. Ikeda,
H. Yamazaki, I. Watanabe, H. Tsuneizumi, K. Tanaka, Y. Watanabe, N. Kitamura, M. Wada and H. Hasebe
Contact
progress@ml.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, December 2023

PREFACE
The RIKEN Accelerator Progress
Report is the annual report of all the
research activities conducted at the
RIKEN
Nishina
Centerfor
Accelerator-Based Science (RNC).
This volume (No. 56) covers theactivities conducted during theJapanese fiscal year 2022 (i.e., April
2022 to March 2023).
With restrictions on social
activity due to the coronavirus
pandemic being gradually eased lastyear, we have been able to reconnect
with friends and families in person
for the first time since the spring of
2020. The same was true researchwise, with many researchers fromabroad visiting to RIKEN toparticipate in the experiments
scheduled at the end of the year. At
the end of October 2022, “TheYoshio Nishina Memorial Event” was successfully held in person as well. With the attendance of guests related to or
have connection with Dr. Nishina who came all the way to Wako, the event turned out to be a great opportunity to sparkinterest not just among the participants but to a wider community about Dr. Nishina’s achievements and the Nishina
Center’s latest initiatives and research activities.
One of the messages that we wanted to communicate through “The Nishina Yoshio Memorial Laboratory” is the“Copenhagen Spirit” that took hold in the research field pioneered by Dr. Nishina. The Spirit is still very much alive inJapan, and I think the main reason is because it matches the philosophy of “Yaoyorozu no kami (eight million gods),” a
traditional Japanese belief that says god exists in everything. Because individual’s ideas and curiosity are the base ofscience and technology, each one can be called a Creator. Every social activity should acknowledge and embracedifferences in one’s sensibility and heighten each other’s originality. It is my wish that we will contribute to realizing apeaceful society where individuals can shine, an endeavor to be achieved when the essence and role of science andtechnology are fully incorporated into society while not repeating the mistakes made about 80 years ago.
95 years later, since the first cyclotron built by Dr. Yoshio Nishina, the superconducting ring cyclotron (SRC) was
registered in the Guinness World Records in April 2022, as the highest energy beam cyclotron which achieves 82,400
MeV of a uranium beam. The SRC was constructed with advanced technology from Japanese industries and completed
in 2006. Since then, the uranium beam has been utilized in more than 100 publications. The other beams also have madea significant contribution to the development of the low energy nuclear physics.
Yasuki Akiba has been appointed as the Director of RHIC Physics Research Group to conduct the sPHENIX
program at RHIC as of April 2022. Tetsuya Ohnishi has succeeded, as the Director of Instrumentation Development
Group as of October 2022. Yoshihide Higurashi has been appointed as the Team Leader of RILAC Team as of October
2022.
In March 2023, an event celebrating three decades of collaboration between RAL and RIKEN was organized. The
RIKEN-RAL Muon Facility was concluded at the end of March. The muon programs have produced over 500
publications, including muon-catalyzed fusion, condensed matter physics and chemistry and battery materials, and havemade new departures in international collaborations, involving South-East Asian countries such as Indonesia, Malaysia,
and Thailand. A new partnership between ISIS RNC has been established since April 2023 to encourage collaborationin areas of accelerator-based sciences.
Many outstanding research results were obtained at RNC last year. Twelve press releases were disseminated in
FY2022. Selected strides made in 2022 have been compiled in the “Highlights of the Year” section in this volume,
which show successful multi-disciplinary activities of RNC for science, technology, and innovation. One of thehighlights was the successful observation of four neutron states by using a different method to observe the phenomenon
already observed few years ago. This research achievement has been chosen by the Institute of Physics as one of the“Top 10 Breakthroughs of the Year for 2022.” The discovery of 39Na was featured by the YouTube program of“Periodic Table of Videos.” The first mass measurement with Rare-RI Ring was published to give an impact to the r-

process path. Reduction of chiral condensate was found through precise observation of pionic atomic states.
Members of RNC received various awards. Kimiko Sekiguchi received the “42nd Saruhashi Prize” and Pieter
Doornenbal received the “Friedrich Wilhelm Bessel Research Award.” The members of the Beam Mutagenesis Group
were also awarded. Tomoko Abe received the “10th Wada Memorial Award,” Tomoko Abe, Yusuke Kazama, andTomoya Hirano received the “Japanese Society of Breeding Award,” and Tomoko Abe, Hiroyuki Ichida, and Ryohei
Morita received the “Japanese Society of Crop Science Best Paper Award.” The “Young Presentation Award by theBeam Physics Study Group” was presented to Yasuyuki Morita. Yusuke Kazawa was awarded the “Atomic Energy
Society of Japan Data Division Encouragement Award.” Kai Kikuchi and Rurie Mizuno were presented the “29thInternational Conference on Low Temperature Physics Poster Award” and “Outstanding Presentation Award,”
respectively. The “2022 RIKEN Awards” included the “EIHO Award” presented to Hiromitsu Haba, “BAIHO Award”
presented to Takashi Abe and Takaharu Otsuka, Yoshitaka Yamaguchi and Makiko Nio, and “OHBU Award” presented
to Yudai Shigekawa and Yasushi Abe.

Hiroyoshi Sakurai
Director
RIKEN Nishina Center for Accelerator-Based Science

CONTENTS

RIKEN Accel. Prog. Rep. 56 (2023)

C O N T E N T S
PagePREFACEGRAVUREFEATURE ARTICLE
Nuclear masses weigh heavily with us····································································································S1

Ⅰ. HIGHLIGHTS OF THE YEAR
Discovery of 39Na····························································································································
D. S. Ahn et al.

S7Study of the N = 32 and N = 34 shell gap for Ti and V by the first high-precision multireflection time-of-flight massmeasurements at BigRIPS-SLOWRI·····································································································
S. Iimura et al.

S9Charge-changing cross sections for 42–51Ca and effect of charged-particle evaporation induced by neutron removal
		reactions ····································································································································
M. Tanaka et al.

S10

Probing optimal reaction energy for synthesis of element 119 from 51V+248Cm reaction with quasielastic barrier
distribution measurement···················································································································
M. Tanaka et al.

S11β-delayed one and two neutron emission probabilities south-east of 132Sn and the odd-even distribution of the r-process		abundances···································································································································
V. H. Phong et al.

S12

Various nuclear structures in 140Xe studied by β decay of ground and isomeric states in 140I······································
A. Yagi et al.

S13

Observation of a correlated free four-neutron system··················································································
M. Duer et al.

S14

Isoscaling in central Sn + Sn collisions at 270 MeV/nucleon·········································································
J. W. Lee et al.

S15

Breakup of proton halo nucleus 8B at near-barrier energies···········································································
L. Yang et al.

S16

Discovery of new isotope 241U and systematical mass measurement of neutron-rich Pa-Pu nuclei with KISS-MRTOF
system··································································································································
T. Niwase et al.

S17α-cluster structure of 12C from first principles····························································································
T. Abe et al.

S18

Isovector density and isospin impurity in 40Ca··························································································
H. Sagawa et al.

S19

Large amplitude collective motion in 44S·································································································
Y. Suzuki et al.

S20

Measurement of flavor asymmetry of light-quark sea in the proton with Drell-Yan dimuon production
		in p + p and p + d collisions at 120 GeV·································································································
K. Nakano et al.

S21

Energy measurement of beam from SRC for GUINNESS WORLD RECORDSTM registration·································
H. Okuno et al.

S22Development of new ionization chamber specialized for high Z beam (II)··························································
M. Yoshimoto et al.

S23

Atomic-number identification of heavy RI beams using the energy loss in a Xe-based gas······································
T. Sumikama et al.

S24

Improved transmission of OEDO··········································································································
T. Chillery et al.

S25

RIKEN Accel. Prog. Rep. 56 (2023)

CONTENTS

Operation test of kicker system with new PFN capacitors·············································································
Y. Yamaguchi et al.

S26

Design of radiation shield for RI production beam line················································································
A. Akashio et al.

S27

Amorphous to polycrystalline phase transition in La2O3 films grown on a silicon substrate forming
Si-doped La2O3 films························································································································
R. Lee, A. Kim, T. Ikeda et al.

S28

Proton hyperpolarization relay from nanocrystals to liquid water····································································
K. Tateishi et al.

S29

Estimation of the on-site Coulomb potential in La2CuO4: A μSR and DFT Study··················································
M. R. Ramadhan and I. Watanabe

S30

Comparison of basis sets for DFT calculation of guanine nucleobase·······························································
W. N. Zaharim et al.

S31

Relative formation probabilities for fluoride and oxyfluoride anions of U, Np, Pu and Am in accelerator mass
spectrometry measurements at VERA····································································································
A. Wiederin et al.

S33

Extraction of 229Th3+,2+ using RF carpet gas cell and observation of internal conversion process of 229mTh·····················
Y. Shigekawa et al.

S34

Innovative targeted alpha therapy for prostate cancer: preclinical evaluation of [211At]PSMA5·································
T. Watabe et al.

S36

Prevention of radionuclide-induced antibody denaturation maintains active targeting and maximizes antitumor efficacy
		in 211At-radioimmunotherapy···············································································································
H. Takashima et al.

S37

Identification of a sex determining gene in a dioecious plant Silene latifolia·······················································
Y. Kazama et al.

S39

Screening for high-growth mutants in sporophytes of Undaria pinnatifida using heavy-ion beam irradiation·················
Y. Sato et al.

S40

Radio-fluorogenic nanoclay gel dosimeters with reduced linear energy transfer dependence for carbon-ion beam		radiotherapy··································································································································
T. Maeyama et al.
Variability in the net ecosystem productivity (NEP) of seaweed farms······························································
Y. Sato et al.

S41
S43

Ⅱ. RESEARCH ACTIVITIES I (Nuclear, Particle and Astro-Physics)
1. Nuclear Physics
RI beam production at BigRIPS in 2022 ································································································
H. Suzuki et al.
Production cross-section measurements for very-neutron-deficient Ca and As isotopes produced from a 78Kr beamat 345 MeV/nucleon by BigRIPS separator ·····························································································
H. Suzuki et al.
Production cross-section measurements of neutron-rich nuclei in the northeast region of 132Sn by the in-flight fission of a238
U beam at 345 MeV/nucleon ······································································································ Y.
Shimizu et al.
Production of 237Np from 238U beam at BigRIPS························································································
C. Fukushima et al.
Search for the double Gamow-Teller giant resonance using double charge exchange reaction··································
A. Sakaue et al.
Development of dispersion matching optics in OEDO beamline (Retracted on February 1, 2024)···························
S. Hanai et al.
Single-particle states in fp-shell nuclei through 50Ca(d, p)51Ca transfer reaction···················································
C. Ferrera, K. Wimmer et al.
Study of νp-process nucleosynthesis at OEDO ·························································································
D. Suzuki, B. Mauss et al.

1

3

4
5
6
7
8
9

CONTENTS

RIKEN Accel. Prog. Rep. 56 (2023)

		 Study of 130Sn(d, p) reaction in inverse kinematics for r-process nucleosynthesis··················································
			
N. Imai et al.

10

		 Toward the mass measurement of neutron-rich nuclei in the vicinity of N = 126 isotones with SLOWRI/ZD-MRTOF·····
			
H. Ishiyama et al.

11

		Q-moment measurement of isomeric state of 99Zr using spin-aligned beam························································
			
Y. Shinohara et al.

12		 In-beam γ-ray spectroscopy of exotic 79Cu with HiCARI··············································································
			
M. Kaci, S. Franchoo et al.

13

		 Barrier distribution measurement of the 51V + 159Tb system···········································································
			
P. Brionnet et al.

14

		 Excitation functions for the 51V + 159Tb fusion evaporation reaction·································································
			
P. Brionnet et al.

16		 Analysis of proton elastic scattering from 132Sn and 48Ca at 300 MeV/nucleon in inverse kinematics··························
			
T. Harada et al.

18

		 The result of electron scattering with Xe isotopes at SCRIT electron scattering facility··········································
			
H. Wauke et al.

19

		 Beta-delayed proton emission in the decay of 71Kr·····················································································
			
A. Vitéz-Sveiczer et al.

20		 Isomeric state studies using the DTAS detector·························································································			J. A. Victoria et al.

21

		 Progress on the analysis of Pn-values relevant for the formation of the r-process rare-earth peak·······························
			
M. Pallàs et al.

22		 The study of the core-excited component in 11Li························································································
			
Y. Li, Z. Yang, Y. Kubota, and T. Uesaka

23

		 Observation of 9Li + d decay channel in 11Li(p, n) reaction············································································
			
L. Stuhl et al.

25

		 SAMURAI18: comprehensive study of 11Li·····························································································
			
Y. Kubota et al.

26

		 Analysis of 48Cr(p, n) reaction in inverse kinematics···················································································
			
M. Sasano et al.

27

		26

Si + α resonant scattering measurement to study 26Si(α, p)29P reaction rate·······················································
M. J. Kim et al.

28

		 Yield investigation of neutron-rich W isotopes produced by multi-nucleon transfer reactions of 136Xe + natIr·················
			
M. Mukai et al.

29

			

		 First application of mass measurements with the Rare-RI ring reveals the solar r-process abundance trend at A = 122
		and A = 123···································································································································			
S. Naimi et al.
		 Direct determination of the atomic mass of 189W························································································
			
M. Mukai et al.

30
31

2. Nuclear Physics (Theory)
		 Spatial correlation of a particle-hole pair with a repulsive isovector interaction···················································
			
K. Hagino and H. Sagawa

33

		 Momentum-space structure of dineutron in 11Li·························································································
			
M. Yamagami

34

		 He cluster formation in light neutron-rich nuclei························································································
			
H. Motoki et al.

35

		 Energy spectrum of 15
Ξ C and the ΞN two-body interaction·············································································
			 Y. Tanimura et al.

36		 Microscopic collective inertial masses for nuclear reactions in the presence of the nucleonic effective mass·················
			
K. Wen and T. Nakatsukasa

37

		 Gamow-Teller transitions in magic nuclei calculated based on the charge-exchange subtracted second random phase		 approximation································································································································
			
M. J.Yang, H. Sagawa et al.

38

RIKEN Accel. Prog. Rep. 56 (2023)

CONTENTS		 Indication of α clustering in the density profiles of 44,52Ti··············································································
			
W. Horiuchi and N. Itagaki

39		 Enhanced moments of inertia for rotation in neutron-rich nuclei·····································································
			
K. Yoshida40

		 Does the second-order operator in the adiabatic expansion contribute to the collective mass?···································
			
K. Sato41

3. Nuclear Data
		 EXFOR compilation of RIBF data in 2022······························································································
		 S. Shin et al.

43		 Measurement of isotopic production cross section on 99Tc via protonand deuteron-induced reactions··························
			
R. Matsumura et al.

44		 Generating scattering data using Gaussian process regression········································································
			
S. Watanabe et al.

45

4. Hadron Physics—
		 Transverse single spin asymmetry for forward neutron production in polarized p + p collisions at √ s = 510 GeV············
			 M. H. Kim et al.

47

		 EIC activities in Japan······················································································································
			
Y. Goto et al.

48

		 Impact studies for transverse spin measurements at the EIC··········································································
			
R. Seidl

49

		 Zero degree calorimeter for the ePIC experiment·······················································································
			
S. Shimizu et al.

50

		 Centrality dependence of charm and bottom quark suppression in Au + Au collisions at RHIC·································
			
T. Hachiya et al.

51

		 Study of v2 depending on multiplicity with ZDC energy event categorization·····················································
			
R. Takahama et al.

52

		 Completion of Bus-Extender development for sPHENIX INTT······································································
			
T. Hachiya et al.

53

		 Development of graphical user interface application for sPHENIX-INTT LV system·············································
			
M. Watanabe et al.

55

		 Detection efficiency of sPHENIX-INTT by cosmic ray measurements and its timing dependence······························
			
Y. Namimoto et al.

57

		 MIP measurement for mass production of sPHENIX-INTT ladder with a positron beam········································
			
Y. Sugiyama et al.

58		 The LV power system of INTT detector at RHIC·······················································································
			
W. C. Tang et al.

59		 Signature of the gluon orbital angular momentum······················································································
			
S. Bhattacharya et al.

60

5. Hadron Physics (Theory)
6. Particle Physics
		 QST algebra··································································································································			
Y. Akiba

61

		 Twelfth-order QED contributions to the muon g − 2··················································································
			
R. Yamazaki and M. Nio

62

7. Astrophysics and Astro-Graciology
		 Demonstration of multiplexing lobster-eye optics······················································································
			
Y. Zhou, T. Mihara, et al.

63		 Direct determination of the activation energy for diffusion of OH radicals on water ice··········································
			
Y. Nakai et al.

64		 Polarized X-rays emitted from a magnetar·······························································································
			
K. Uchiyama et al.

65

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RIKEN Accel. Prog. Rep. 56 (2023)

8. Accelerator
		 Production of high intense Ca-ion beam for RILAC II acceleration·································································
			
T. Nagatomo et al.

67		 Upgrade of rf control system for RILAC injector·······················································································
			
K. Yamada et al.

68

		 Beam profile measurement using helium gas light emission for superheavy element search experiment·······················
			
T. Watanabe et al.

69		 Improvement of the high temperature superconducting properties for the HTc SQUID current meter··························
			
T. Watanabe et al.

70

		 Development of auto-tuning system using Bayesian optimization for ion optics in primary beam line with 26 electric nA
		 Kr beam ····································································································································
			
T. Nishi et al.

71		 Development and test operation of the prototype of the new beam interlock system for machine protection of RIBF·······
			
M. Komiyama et al.

72		 Activation of temperature control in the RILAC cooling water·······································································
			
K. Yamada et al.

73

		 2022 operational report of the Nishina RIBF water-cooling system··································································
			
T. Maie et al.

74		 Relationship between instantaneous voltage drops at RIKEN and influence on transmission power lines·····················
			
M. Kidera et al.

75

		 Status of vacuum pumping systems in accelerator facilities···········································································
			
Y. Watanabe et al.

76

9. Instrumentation
		 Development of an automatic particle identification system for the BigRIPS separator···········································
			
Y. Shimizu et al.

77

		 Introduction and performance evaluation of a new data acquisition system for germanium detectors··························
			
H. Takeda et al.

78

		 Conceptual design of new high-power beam dump for BigRIPS·····································································
			
Y. Togano et al.

79		 Energy-degraded beam on BigRIPS F0··································································································
			
H. Otsu et al.

80

		 FPC board design for TOGAXSI silicon trackers·······················································································
			
K. Higuchi, J. Tanaka et al.

82

		 Study of the position dependence of the large GAGG(Ce) calorimeter······························································
			
R. Tsuji et al.

83

		 Integration of VX2740B digitizer into babirl DAQ·····················································································			
S. Ogio et al.

85

		 Integration of DABC and babirl DAQ····································································································
			
S. Takeshige et al.

86

		 Fokker-planck analysis for particle motion in RUNBA················································································
			
M. Wakasugi et al.

87

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

88		 Improvement of gas inlet system for FRAC at SCRIT facility········································································
			
S. Iimura et al.

89

		 Charge state distributions of 138Ba ions trapped in the SCRIT·········································································
			
R. Ogawara et al.

90

		 Installation of the NEBULA-Plus neutron array························································································
			The EXPAND Collaboration91		 Silicon tracker array for RIB experiments at SAMURAI··············································································
			
A. I. Stefanescu et al.

92

RIKEN Accel. Prog. Rep. 56 (2023)

CONTENTS		 Development of a new configuration for the liquid hydrogen target·································································
			
X. Wang et al.

93		 Improvements in cooling operations of the SAMURAI magnet······································································
			
H. Sato et al.

94		 The extraction test aiming for the laser spectroscopy of actinoid elements by PALIS·············································
			
T. Sonoda et al.

95

		 Charge population investigation for the 248Cm fission products extracted from a helium gas catcher···························
			
A. Takamine et al.

96

		 Offline measurement of 248Cm fission products at ZD-MRTOF·······································································
			J. M. Yap, A. Takamine, et al.

98

		 Development of a high-speed digital data acquisition system for the ZD-MRTOF and β-decay experiments at F11·········
			V. H. Phong et al.

99		 The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN’s RIBF facility·····················
			
M. Rosenbusch et al.

100

		 Improvements in the performance of the KISS MRTOF···············································································
			
P. Schury et al.

102

		 Development of cryogenic helium gas cell at KISS····················································································
			
Y. Hirayama et al.

103

		 Development of light collection system for collinear laser spectroscopy····························································
			
M. Tajima et al.

104

		 Measuring the stopping position of the energetic radioactive Rb beams in superfluid helium····································
			
M. Ito et al.

105

		 Highly-efficient γ-ray linear polarization measurement by multi-layer CdTe Compton Camera·································
			
S. Go et al.

106

		 Charge-exchange reaction of francium ions using an yttrium neutralizer···························································
			
H. Nagahama et al.

107

		 Absorption spectroscopy measurements of molecular iodine for magneto-optical trapping of francium atoms···············
			
K. Nakamura et al.

108		Improved 6He beam production at CRIB with MWDC and degraders·······························································
			
H. Yamaguchi et al.

109

		 Progress on double photon coincidence imaging with 67Cu and 169Yb·······························································
			
K. Shimazoe et al.

110

		 Status of the J-PARC E16 experiment in 2022··························································································
			
S. Yokkaichi

111

		 Preparation status for sPHENIX experiment and INTT detector for Run23 at RHIC··············································
			
I. Nakagawa et al.

112

		 Preliminary results of INTT beam test 2021 at ELPH··················································································
			
C. W. Shih et al.

113

		 Accelerator report INTT onlmon progress summary 2023············································································
			
J. Bertaux et al.

114

		 Performance of a new operating system by FELIX board for INTT in sPHENIX·················································
			
G. Nukazuka et al.

115

		 Development of a control application for sPHENIX-INTT detector operation·····················································
			
H. Imai et al.

116

		 Forward calorimeter upgrade project in ALICE·························································································
			
T. Chujo et al.

117

		 Beam test data analysis of the ALICE FoCal-E pad prototype········································································
			
M. H. Kim

118

		 Activation measurement of copper by 238U irradiation·················································································
			
A. Akashio et al.

119

		 RIKEN Wi-Fi service in the RIBF experimental area··················································································
			
H. Baba et al.

120

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RIKEN Accel. Prog. Rep. 56 (2023)

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

121

		 CCJ operations in 2022·····················································································································
			
S. Yokkaichi et al.

122

Ⅲ. RESEARCH ACTIVITIES II (Material Science and Biology)

1. Atomic and Solid State Physics (Ion)
		 Control of electrical conductivity in diamond by boron-implantation using an ECR ion source·································
			
H. Yamazaki et al.

123		 Lattice sites of 23Ne implanted in single-crystal ZnO studied by β-NMR/NQR spectroscopy····································
			
H. Yamazaki et al.

124

		 Evaluation of horizontal irradiation for SiC vertical diodes···········································································
			
M. Iwata et al.

125		 Improvement of the signal-to-noise ratio of Rb D1 fluorescence in superfluid helium using picosecond time-resolved
		detection ····································································································································
			
H. Endo et al.

126

		 Development of a spin polarized RI atomic beam apparatus the using atomic resonance method·······························
			
K. Imamura et al.

127

		 Application of 21O β-NMR spectroscopy to study the microscopic properties of CuO single crystal····························
			
A. Gladkov et al.

128		 Precise measurement of diffraction structures in capillary laser sight for ion microbeam irradiation to mammalian cells···			
M. Kurino et al.

129

2. Atomic and Solid State Physics (Muon)
		 DFT investigations on magnetic properties with Muon in La2CuO4 using LSDA + U functional································
			
S. Charoenphon et al.

131		 The effect of particle size on magnetic properties regarding La2CuO4 nanoparticles··············································
			
A. E. Putri et al.

133		 Sample synthesis of Nd2Ru2O7 for researches by using quantum beams·····························································
			
M. A. Syakuur et al.

134

		 Probing internal fields induced by Ru and Nd spin ordering on Nd2Ru2O7 using continuous muon beam······················
			
U. Widyaiswari et al.

135

		 Magnetic short-range order in a hyperkagome lattice alloy Mn3CoSi································································
			
D. P. Sari et al.

136

		 TF-μSR study of YbCu4Ni··················································································································
			
T. Taniguchi et al.

137

		 μSR study of slightly pressurized organic superconductor κ-(ET)4Hg2.89Br8, II·····················································
			
D. P. Sari et al.

138

3. Radiochemistry and Nuclear Chemistry
		 Extraction behavior of Nb and Ta in HF solution with F-form TOMA resin························································
			
S. Goto and M. Higuchi

141

		 Online solid-liquid extraction of 255No with the polymer-supported crown ether···················································
			
E. Watanabe et al.

142

		 Coprecipitation behavior of element 102, nobelium, with barium sulfate···························································
			
S. Otaka et al.

143		 Coprecipitation of 133Ba, 226Ra, and 152Eu with calcium oxalate for the chemical study of nobelium····························
			
R. Nakanishi et al.

144		 Improved chemical separation scheme of Pa isotopes from a 232Th target toward observing the radiative decay of229m
		Th using 229Pa·····························································································································
			
Y. Shigekawa et al.
		 Preparation of a small high-density 229Th target for the X-ray pumping of the 229Th nuclear clock isomer·····················
			
Y. Shigekawa et al.

145
147

RIKEN Accel. Prog. Rep. 56 (2023)

CONTENTS		 Development of 211Rn/211At generator through liquid phase recovery of radon and ionic liquid extraction of astatine········
			
Y. Nagai et al.
		 The feasibility study for the medical radioisotope: astatine-211 production by the gas cell-based laser ionization
		technique ····································································································································
			
T. Sonoda et al.

149

150

		 Progress of 211At production at the RIKEN AVF cyclotron············································································
			
X. Yin et al.

151		 Improvement of chemical separation method for theranostic radionuclide 141Ce···················································
			
K. Ooe et al.

153

		 Chemical separation of 139Ce from a natLa target using LN resin······································································
			
K. Akiyama et al.

154

		 Astatine-211-labeled gold nanoparticles for targeted alpha-particle therapy via intravenous injection·························
			
X. Huang et al.

155		 Efficacy of nuclear medicine therapy with 67CuCl2 in mice bearing LS180 colon cancer········································
			
Y. Fujisawa et al.

156

		 Accelerator-based synthesis of rhenium-186 that enables high spatial resolution imaging·······································
			
S. Takeda et al.

158

		44m

Sc-DOTA-TATE imaging with a cancer disease mouse model for multiple-isotope PET imaging···························
T. Fukuchi et al.

160

		 Source preparation technique for Ag 211At for alpha spectroscopy····································································
			
S. Fujino et al.

162		 Radioactivity calibrations of 225Ac and 211At·····························································································
			
K. Arai et al.

164		 Activation cross sections of 28Mg via α-particle-induced reaction on 27Al···························································
			
M. Aikawa et al.

165

		 Production cross sections of 47Sc via α-particle induced reactions on natCa··························································
			
M. Aikawa et al.

167

		 Production cross sections of 52gMn in α-particle-induced reactions on natV··························································
			
G. Damdinsuren et al.

169		 Activation cross sections of deuteron-induced reactions on natCr up to 24 MeV····················································
			
H. Huang et al.

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

172

		 Reexamination of production cross sections of 153Sm via α-particle induced reactions on natNd·································
			
M. Aikawa et al.

173

		 Activation cross sections of 7Li-induced reactions on natSm···········································································
			
M. Aikawa et al.

174		 Activation cross sections of deuteron-induced reactions on natural gadolinium up to 24 MeV··································
			
D. Ichinkhorloo et al.

175

		 Production yields of 165Er and 169Yb via 24-MeV deuteron induced reactions······················································
			
Y. Shigekawa et al.

176

		 Activation cross sections of α-particle-induced reactions on natTa····································································
			
S. Takàcs et al.

178

		 Activation cross sections of deuteron-induced reactions on natRe·····································································
			
M. Aikawa et al.

180

		 Production cross sections of 189gIr in α-particle-induced reactions on natRe··························································
			
G. Damdinsuren et al.

181

		 Production cross sections of 198gAu in proton-induced reactions on natPt·····························································
			
G. Damdinsuren et al.

183

		 Production cross sections of 211Rn via 7Li-induced reaction on 209Bi·································································
			
N. Ukon et al.

185

			

CONTENTS

RIKEN Accel. Prog. Rep. 56 (2023)

4. Radiation Chemistry and Biology
		 Sample preparation for ion-beam irradiation for biological experiments····························································
			
Y. Hayashi and T. Abe

187

		 Identification of causal site for an Arabidopsis C30-144-as3 mutant·································································
			
A. D. Nagalla et al.

189

		 Analysis of splicing patterns in Arabidopsis egy1-4 carrying argon-induced mutations in the intron 3-exon 4 region·······
			
A. Sanjaya et al.

190

		 Irradiation of seeds with C-ion and Ar-ion beams for Streptocarpus mutagenesis to understand leaf meristem genetics····			
K. Nishii et al.

191

		 Comprehensive effects of heavy-ion beam irradiation on sweet potato (Ipomoea batatas [L.] Lam.)···························
			
H. Park et al.

193

		 Growth inhibition of marine red alga Agardhiella subulate through C-ion beam irradiation·····································
			
K. Tsuneizumi et al.

194		 Semi-automated high-throughput microbial DNA extraction protocol for population-scale mutation analysis················
			
Y. Nishimiya et al.

195

		 Heavy-ion irradiation enhanced the post-transcriptional modification of CtIP······················································
			
M. Izumi et al.

196

		 Examination of the direct visualization toward adverse events caused by space radiation········································
			
A. Sakaue-Sawano et al.

198

		 Effects of heavy-ion beam irradiation on non-model fruit fly, Drosophila miranda···············································
			 M. Ogawa et al.

200

Ⅳ. OPERATION RECORDS
		 Program Advisory Committee meetings for nuclear physics and for materials and life sciences································
			
H. Ueno203

		 Electric power consumption of RIKEN Nishina Center in 2022······································································
			
M. Kidera et al.

204

		 RILAC operation····························································································································
			
H. Yamauchi et al.

205

		 Operation report on the RIKEN AVF cyclotron for 2022··············································································
			
K. Yadomi et al.

206

		 Operation report on ring cyclotrons in the RIBF accelerator complex·······························································
			
K. Kobayashi et al.

207

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

208

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

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

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

213

		 Variation of impurity gas in recovered helium gas for liquid-helium supply and recovery system······························
			
M. Nakamura et al.

215

		 Fee-based activities performed by the RI application research group································································
			
A. Nambu et al.

216

Ⅴ. EVENTS
		 Research strategy with open-closed data utilization in nuclear physics experiments··············································
			
H. Baba217

		 RIKEN open day 2022······················································································································
			
T. Ikeda et al.

218

RIKEN Accel. Prog. Rep. 56 (2023)

CONTENTS		 Physics of RI: Recent progress and perspectives························································································
			
M. Kimura et al.

220		 Predictions for sPHENIX···················································································································
			
M. E. Connors et al.

221		 International workshop on “Hadron Physics with Kaon Beam and Related Topics”···············································
			
F. Sakuma

222

		 The 10th users’ meeting on mutation breeding in RIBF “Sustainable society and creation of specialty products realized
		 by ion-beam breeding”······················································································································
			
T. Abe et al.

223

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

1. Organization Chart·················································································································

225

			

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

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

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

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

229

			

6. International Collaboration (as of March 31, 2023)···········································································

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

235

			

8. RIKEN Awards·····················································································································

235

		 Center Director·······························································································································

237

		Laboratories
			

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

239

			

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

246

			

Nuclear Spectroscopy Laborarory··································································································

252

			

High Energy Astrophysics Laborarory·····························································································

259

			

Nuclear Many-Body Theory Laborarory··························································································

267

			

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

271

				

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

272

				

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

275

			

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

277

			

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

279

				

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

280

				

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

281

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

282

			

285

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

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

286

				

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

287

			

Research Facility Development Division			

Accelerator Group····················································································································

				

289

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

291

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

292

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

293

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

295

CONTENTS

RIKEN Accel. Prog. Rep. 56 (2023)

				

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

297

				

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

299

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

300

			

301

Instrumentation Development Group······························································································				SLOWRI Team·················································································································

303

				

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

306

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

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

311

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

312

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

316

				

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

318

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

320

			

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

323

				

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

324

				

Plant Genome Evolution Research Team···················································································328

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

330

			

				

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

331

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

339

			

Subnuclear System Research Division			Strangeness Nuclear Physics Laboratory··························································································

341

			

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

346

			

RHIC Physics Research Laboratory································································································

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

355

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

357

				

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

361

				Computing Group··············································································································

366

			

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

371

			

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

374

			

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

376

				

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

377

				

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

378

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

380

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

383

			

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

384

			

Wako Nuclear Science Center, IPNS (Institute of Particle and Nuclear Studies),

			

				

KEK (High Energy Accelerator Research Organization)·································································

393

Ⅶ. APPENDICES
		 Symposia, Workshops & Seminars········································································································

397

		Events····································································································································

405

		 Press Releases································································································································

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		News····································································································································

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		Preprints ····································································································································

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RIKEN Accel. Prog. Rep. 56 (2023)

FEATURE ARTICLE

RIKEN Accel. Prog. Rep. 56 (2023)

Nuclear masses weigh heavily with us

As a self-organizing quantum system, the nucleus
makes every eﬀort to reduce its mass. As a naturalconsequence, the nuclear mass contains all the information on mechanisms that stabilize the nucleus. Thesemechanisms can be traced back using the nuclear massdata.
In 1919, Francis William Aston performed the ﬁrst
successful mass measurement and discovered many isotopes using his mass spectrograph. At that time, themass resolution was approximately 1%. The subsequent century has witnessed incredible developments
in techniques used for measuring nuclear masses. The
most established and famous techniques of precisionmass measurements are the Penning trap method andthe Schottky method using a storage ring.
Unfortunately, neither of the methods can be applied to mass measurements of rare nuclei produced at
the RI Beam Factory (RIBF). This is solely becauseof their short lifetimes of ≫1 s. In the long measurement time (>1 s) of the Penning trap and the Schottky
methods, the short-lived nuclei decay to their daughters, which prevents us from measuring their masses.
The main physics cases in nuclear mass measurements
at RIBF involve the magicity and the r-process nucleosynthesis, both of which require a mass precision of
100 keV, or δm/m ∼10−6 . Since the statics expected
for rare nuclei are as small as ∼102 , a mass resolving
power of 105 or better is mandatory in their studies.
The unprecedentedly fast mass-measurement technique with a mass resolving power as high as m/∆m >105 has been highly desired, but accomplishing it is a
big challenge for nuclear physicists.
Scientists at RIKEN, KEK, and CNS have tackled
this problem and have recently succeeded in measuring masses of rare nuclei: The ﬁrst one is the TOFBρ mass measurement using the long OEDO beamline
coupled with the SHARAQ spectrometer. The measurement combining a ﬂight length of 105 m (one path)and the high-resolution magnetic system with a controlled correction of higher-order aberrations enables
an extremely short measurement time of 0.0005 ms
with a reasonable resolving power of >104 and a higheﬃciency of ∼100%.
The second is an isochronous mass measurement using the Rare RI Ring (R3). R3 is the world’s ﬁrst
cyclotron-type storage ring with an individual injection
capability. The setup leads to a 0.7-ms measurement
time with a resolving power > 3 × 105 .
The third is the multireﬂection time-of-ﬂight(MRTOF) mass spectrograph combined with a gas
catcher system. This versatile and “portable” device
can be placed at any beamline to accept a wide varietyof nuclei, whose masses are measured in several tens of

ms (including the time needed to stop the ions) witha high resolving power of 106 .
The combined use of the abovementioned three techniques with diﬀerent characteristics, shown in Fig. 1,
opens a broad spectrum of research opportunities at
RIBF.

Fig. 1. Mass precision and nuclear half-life regions coveredby the three mass measurement methods.

TOF-Bρ mass measurement using OEDOSHARAQThe OEDO-SHARAQ system, initiated collaboratively by CNS, the University, of Tokyo and RIKEN
Nishina Center is promoting the program of direct
mass measurements of radioactive nuclei far from the βstability line. In 2009, the OEDO-SHARAQ program
started with the installation of the SHARAQ spectrometer1) and a dispersion-matched High-Resolution
beamline2) (renamed by OEDO beamline in 2017) into
the downstream of the BigRIPS separator3) at the
RIBF facility.
Atomic masses of very short-lived nuclei have been
determined so far by various time-of-ﬂight (TOF)
methods. In our system, the TOF magnetic-rigidity(TOF-Bρ) method, developed at GANIL,4) has been
adopted, and further sophistication in its ion optics
and detector performance has been implemented forthe measurements. The principle of mass determination using the TOF-Bρ method can be simply expressed by the following relation:
√( )
2
Bρ
ct
m
=
− 1,
(1)
q
c
L
where m, q, c, t, and L are the nuclear mass, atomic- S1 -

RIKEN Accel. Prog. Rep. 56 (2023)

FEATURE ARTICLE

charge, speed of light in vacuum, TOF, and the ﬂightpath length, respectively. This relation corresponds
to the Lorentz force in a magnetic ﬁeld, and indicatesthat the mass-to-charge ratio (m/q) is determined by
TOF as long as the ﬂight-path length and the magnet ﬁeld of the beamline are ﬁxed. However, because
the ﬂight-path length is indeed dependent on the incident condition of the short-lived nuclei, we perform an
event-by-event correction of the ﬂight-path length using the trajectory information obtained at the startingand ﬁnal foci of the beamline. The essential point thathas led to the success of our direct mass measurement
program has been the high-resolution performance ofthe system.
The detector setup for the mass measurements isshown in Fig. 2. The CVD diamond detectors were
installed at F3 and S2 to measure the TOF. The CVD
diamond detector was developed at CNS to achieve
high-resolution timing and high-rate capability.5) The
low-pressure multiwire drift chambers (LP-MWDCs)6)
were used for beam tracking at F3 and S2, and provided beam-trajectory information that is mandatory
for accurate corrections of the ﬂight-path lengths. A
delay-line parallel-plate avalanche counter (DL-PPAC)
installed at S0 measured the Bρ values of the beam
particles. The m/q values of the individual short-lived
nuclei were determined based on the combination ofthese measured quantities on an event-by-event basis.
Additionally, a silicon solid-state detector (SSD) wasused to identify the atomic numbers. The delayed
γ-ray detection system was placed at the end of thebeamline to search for the unknown isomeric states in
the radioactive nuclei.

Fig. 2. Experimental detector setup in the OEDO-SHARAQ
system for the direct mass measurements.

An advantage of the SHARAQ mass measurements
is its accessibility to very short-lived isotopes, whose
lifetimes are less than 1 ms, with its high transmission
eﬃciency, because the TOF of the system is as short as∼500 ns. With this capability, the system is expected
to enable the measurement of nuclear masses on the
dripline.

2- S2 -We have successfully measured the atomic massesof very neutron-rich Ca and Ti isotopes towards the
dripline by a single setting of the BigRIPS separator
and the SHARAQ spectrometer. These new masses arecovered with the region connecting the emergence ofmagicities at N = 32 and 34 and the island-of-inversion
at N = 40. The work has clearly exhibited the sudden emergence of magicity in 54 Ca.7) Moreover, the results for Ti isotopes reveal an onset of the Jahn-Teller
stability around 62 Ti,8) indicating shell quenching at
N = 40 based on the comparison with the theoreticalmass predictions.9)
These experiments have demonstrated that our experimental technique has capabilities to eﬃciently pin
down the mass irregularities and provide essential information on its onset mechanism based on mass evolution. Recently, the ﬁrst TOF-Bρ mass measurements
after the construction of the OEDO system were performed to access the mass region of two-proton radioactivity.10) The TOF-Bρ method excels in extending the mass data toward the nuclear drip lines. We
will extend our challenge toward the 78 Ni and 100 Sn
regions in the near future.
Isochronous mass measurement with the rare
RI ring
In the decade after the R3 was built, we have successfully conducted its commissioning using a primarybeam, validation of the mass measurement method using unstable nuclei with known masses, and precise
mass measurements. Recently, the mass of 123 Pd, oneof the nuclei near the second peak of the r-process,was successfully determined.11) The impact of the measured mass on the heavy element synthesis was investigated by inputting the new mass value into the rprocess network simulations from which its eﬀect on
the probability of neutron capture and neutron emission after beta decay were evaluated. The compositions observed in the solar system can be reproducedwith the new mass value.
Figure 3 illustrates the mass measurement schemeof the R3. The mass measurements for such nuclei
have been achieved by our bold move to connect a
cyclotron and a storage ring, which have been known
to be essentially incompatible, taking the advantageof the “long” fragment separator. The key point of
this scheme is to know, prior to injection, that thenucleus of interest is produced in the ﬁrst section of the
BigRIPS and to inject it into R3. The masses are thendetermined event-by-event by performing isochronous
mass spectrometry (IMS).12,13)
In RIBF, various unstable nuclei are produced by
the in-ﬂight ﬁssion of the uranium beam or the projectile fragmentation of heavy-ion beams such as xenon,
krypton, etc. Their extremely low production rate
makes the timing of production completely random.

RIKEN Accel. Prog. Rep. 56 (2023)

FEATURE ARTICLE

SRC

KickersystemTargetPID(Bρ-TOF-dE)
TimingT rignal
ger sig

missiotransre-PID(dE-E)n

IMS at R3

Produced randomly detector
Rare event

Fig. 3.

time

Beamline

Conceptual design and method for measuring the mass of short-lived rare nuclei using R3.

The species of the produced nuclei can be identiﬁed onan event-by-event basis using the Bρ-TOF-dE methodin the F0–F3 section of BigRIPS.14) Subsequently, theidentiﬁed isotope passes though the timing detector
placed at F3. Using the timing and energy-loss information from the detector, the signal to trigger theR3 kicker system is generated only for the isotopes
of interest. Synchronization of the kicker excitation
to the arrival of the isotope beam is the key technology enabling the unique combination of a cyclotron
and a storage ring. It should also be noted that theRF signal from the accelerator is utilized to eﬃciently
reduce the trigger rate by ﬁltering the signals corresponding to unnecessary events. Using this setup, we
have realized the isotope-selectable self-triggered injection, called the individual injection, for the ﬁrst time.
The injected isotope is circulated in R3 for certain
turns (typically ∼2000) and extracted after ∼1 ms.
The revolution time is obtained by dividing the ﬂighttime between injection and extraction by the numberof turns. Further, the extracted events are identiﬁed
once again for veriﬁcation (re-PID). The ratio of therevolution times of the nucleus of interest to a reference nucleus, whose mass is well known, is use to accurately determine the mass. It should be noted herethat isochronism of R3 holds only for a single isotope,
the reference nucleus in many cases and the revolution
time of the nucleus of interest has momentum dependence. Thus a small correction is introduced using thevelocity, β, or Bρ determined by the measurements
prior to injection.
The main factor crucial for the precision of thederived mass is the degree of isochronism, including
the magnetic ﬁeld ﬂuctuation. Isochronism is deﬁned by the spread of the revolution time, dT/T, in
the acceptance of the ring. A standard deviation of
dT /T ∼ 2.8 × 10−6 for a high degree of isochronism
has been achieved at R3 for the full momentum acceptance (dp/p ∼ ±0.3%). This leads to a high mass
resolving power of 3.5 × 106 . We have established ascheme that can determine masses of the order of 10−6
with a measurement time of less than 1 ms. Further

eﬀorts are ongoing to increase the mass resolving power
and injection eﬃciency by upgrading the kicker system,15,16) and by ﬁne-tuning the ion optics. In the near
future, it is expected to be able to derive the masses ofnuclei in a region that can only be achieved with the
R3, i.e., the nuclei having half-lives of <10 ms, andextremely rare that one can be extracted in a day.
MRTOF mass measurement
Three multi-reﬂection time-of-ﬂight mass spectrographs (MRTOF-MS) are in operation at RIBF. Oneof them is called ZD-MRTOF, which is located behind the ZeroDegree spectrometer (ZDS), combinedwith an RF-carpet-type cryogenic He gas catcher(RFGC)17,18) in the SLOWRI project (Fig. 4). The
fast (>100 MeV/nucleon) RIs provided from BigRIPS
are stopped in the He gas and extracted as slow(<10 eV) RI ions from the RFGC using RF ion carpets. They are then guided into an ion trap, accumulated, cooled, and injected into the mass spectrograph(Fig. 5).19) The ions are reﬂected back and forth between the ion mirrors typically for 600 revolutions corresponding to ≈10 ms at a maximum kinetic energyof 2.5 keV. Currently, the maximum mass resolving
power has reached to 106 .
Since the location of the ZD-MRTOF is just in frontof the beam dump of ZDS, mass measurements havebeen conducted symbiotically by re-using the RIs fromother experiments carried out upstream without extra
costs. For example, during the in-beam γ-ray experiments (HiCARI campaign) in winter 2020, more than
70 masses on RIs were measured with the ZD-MRTOF
system (Fig. 6). Among them, three isotope masses
have been measured for the ﬁrst time and mass uncertainties of 11 isotope have been signiﬁcantly improved
from the previous ones.
For Ti and V isotopes, the nonexistence of the N =34 empirical two neutron shell-gaps has been revealed
experimentally with the new precision achieved by ourequipment.20)- S3 -

3

RIKEN Accel. Prog. Rep. 56 (2023)

FEATURE ARTICLE

Fig. 4. Photographs of an RF-carpet-type He gas catcher(RFGC) behind ZDS of BigRIPS.

Fig. 6.

Nuclear mass measurements performed with the three MRTOF-MS.

The second MRTOF is located downstream ofthe beamline at the KEK isotope separation system(KISS), which employs a mass spectrograph and a particle identiﬁcation detector for laser spectroscopy. Ingas-cell laser resonant ionization spectroscopies for Os
and Pt isotopes have been conducted with the KISSMRTOF.21,22) In addition, a new isotope of 241 U has
also been discovered by a precise mass measurement
using KISS-MRTOF.23)
The third MRTOF, SHE-Mass, is located behind
GARIS-II at E6. It has been used for mass measurements of super-heavy nuclei such as 257 Db.24) In addition, a 9 MBq 252 Cf ﬁssion source has been installed
just in front of the He gas catcher. Even oﬀ-line, massmeasurements on the ﬁssion fragments have continued
and several ﬁrst mass measurements have been performed.25)
We have a plan to increase this versatile andportable instrumentation at RIBF; an MRTOF-MS
is being installed behind GARIS-III, and a plan isunderway to install an MRTOF-MS with a large He
gas catcher behind SD4 at BigRIPS, which will leadto more opportunities to study unexplored nuclear
species.

4

Fig. 5. Schematic view of MRTOF-MS (top) and a photograph of the ion mirrors behind ZDS of BigRIPS (bottom).

- S4 -

References
1) T. Uesaka et al., Prog. Theor. Exp. Phys. 2012,
03C007 (2012).
2) S. Michimasa et al., Nucl. Instrum. Methods Phys. Res.
B 317, 305 (2013).
3) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204,
97 (2003).
4) N. Orr et al., Phys. Lett. B 258, 29 (1991).
5) S. Michimasa et al., Proc. Sci. INPC2016, 106 (2017).
6) H. Miya et al., Nucl. Instrum. Methods Phys. Res. B
317, 701 (2013).
7) S. Michimasa et al., Phys. Rev. Lett. 121, 022506(2018).
8) S. Michimasa et al., Phys. Rev. Lett. 125, 122501(2020).
9) N.-N. Ma et al., Chin. Phys. C 43, 044105 (2019).
10) S. Hanai et al., in this report.
11) H. F. Li et al., Phys. Rev. Lett. 128, 152701 (2022).
12) H. Wollnik, Nucl. Instrum. Methods Phys. Res. A 258,
289 (1987).
13) J. Trotscher et al., Nucl. Instrum. Methods Phys. Res.
B 70, 455 (1992).
14) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res.
B 317, 323 (2013).
15) Y. Yamaguchi et al., RIKEN Accel. Prog. Rep. 54, 100(2021).
16) Y. Yamaguchi et al., in this report.

RIKEN Accel. Prog. Rep. 56 (2023)

FEATURE ARTICLE

17) A. Takamine et al., in this report.
18) J. M. Yap et al., in this report.
19) M. Rosenbush et al., in this report; Nucl. Instrum.
Methods Phys. Res. A 1047, 167824 (2023).
20) S. Iimura et al., in this report; Phys. Rev. Lett. 130,012501 (2023).
21) H. Choi et al., Phys. Rev. C 102, 034309 (2020).
22) Y. Hirayama et al., Phys. Rev. C 106, 034326 (2022).
23) T. Niwase et al., in this report; Phys. Lett. 130, 132502(2023).
24) P. Schury et al., Phys. Rev. C 104, L021304 (2021).
25) S. Kimura et al., RIKEN Accel. Prog. Rep. 55, 8(2022).

- S5 -

5

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 YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Discovery of 39 Na†
D. S. Ahn,∗1 J. Amano,∗3 H. Baba,∗1 N. Fukuda,∗1 H. Geissel,∗5 N. Inabe,∗1 S. Ishikawa,∗4 N. Iwasa,∗4
T. Komatsubara,∗1 T. Kubo,∗1 K. Kusaka,∗1 D. J. Morrissey,∗6 T. Nakamura,∗2 M. Ohtake,∗1 H. Otsu,∗1
T. Sakakibara,∗4 H. Sato,∗1 B. M. Sherrill,∗6 Y. Shimizu,∗1 T. Sumikama,∗1 H. Suzuki,∗1 H. Takeda,∗1
O. B. Tarasov,∗6 H. Ueno,∗1 Y. Yanagisawa,∗1 and K. Yoshida∗1

Atomic number （Z）

The location of the neutron dripline provides a key
benchmark for advanced nuclear models and theories.
It reﬂects the details of the underlying nuclear structure and interactions, which include the evolution of
the nuclear shell property and associated nuclear deformation. Thus, locating the neutron dripline experimentally provides a signiﬁcant key to understanding the nuclear structure under extremely neutron-richconditions.
In our previous study,1) we searched for the new isotopes 32, 33 F, 35, 36 Ne, and 38, 39 Na to investigate theneutron dripline at ﬂuorine (atomic number Z = 9),neon (Z = 10), and sodium (Z = 11). No events wererecorded for 32, 33 F, 35, 36 Ne, and 38 Na and only one
event was recorded for 39 Na. This enabled us to determine the neutron dripline for ﬂuorine and neon to be
31
F and 34 Ne, respectively, nearly 20 y after 24 O was
conﬁrmed as the dripline nucleus of oxygen (Z = 8).
In this study,2) we conducted a new experiment dedicated to searching speciﬁcally for 39 Na to establishthat it is particle-bound. The new isotope 39 Na has
the mass number A = 3Z + 6, located beyond the previously known most neutron-rich isotope 37 Na, which
was discovered 20 y ago;3) see Fig. 1. It is a strong
candidate to be the dripline nucleus of sodium, and establishing its existence provides a signiﬁcant extension

26Mg

38Mg
35Na

23Na
22Ne

32Ne
27F

19F

39Na

N = 28N = 28

29F

18O

N=
N
=20
20
17B

N = 16N=16

Stable isotopes
Unstable isotopes
Known driplineA
4 4
A ==3Z
3Z+ +Neutron number（N）

39Na

Discoveredin this work

Fig. 1. Section of the nuclear chart indicating the locationof the 39 Na isotope discovered in this study.
†
∗1
∗2
∗3
∗4
∗5
∗6

Condensed from the article in Phys. Rev. Lett. 129, 212502(2022)RIKEN Nishina Center
Department of Physics, Tokyo Institute of Technology
Department of Physics, Rikkyo University
Department of Physics, Tohoku University
GSI Helmholtzzentrum für Schwerionenforschung GmbH
National Superconducting Cyclotron Laboratory, Michigan
State University- S7 -of the neutron dripline and a benchmark for nuclear
structure calculations as well as nuclear mass models.
It should be noted that 39 Na has the neutron number
N = 28, which is normally a magic number.
The search was conducted at the RIKEN RIBF using projectile fragmentation of an intense 48 Ca beamat 345 MeV/nucleon on a 20-mm-thick beryllium target. The projectile fragments including 39 Na were separated and identiﬁed in ﬂight by the large-acceptance
two-stage fragment separator BigRIPS.4,5) The intensity of the 48 Ca beam was as high as ∼540 particle nA.
The particle identiﬁcation was made at the second
stage of the BigRIPS separator, relying on the combination of time of ﬂight (TOF), magnetic rigidity (Bρ),
and energy loss (∆E) measurements, from which the Z
and A/Z values were deduced for each fragment. The
TOF was measured between two thin plastic scintillators installed at the intermediate and ﬁnal foci of thesecond stage. The value of ∆E was measured using
a stack of six identical silicon semiconductor detectors
installed at the ﬁnal focus. The value of Bρ was determined from a position measurement at the intermediate focus using the plastic scintillator that alsomeasured the TOF. The separator setting was tuned
for the optimal transmission of 39 Na. The productionof 36 Ne was also revisited with another separator setting tuned for that of 36 Ne to improve the conﬁdence
level that 34 Ne is the dripline nucleus of neon.
After extensive running, we observed nine events for39
Na and clearly established that the 39 Na nucleus isparticle-bound. Furthermore, no events were observedfor 35, 36 Ne, which is consistent with their particle instability established in our previous work. The measurement enabled us to signiﬁcantly improve the conﬁdence level and hence ﬁrmly determine that 34 Ne is
the dripline nucleus.
The particle stability of 39 Na, established by thepresent discovery, suggests the occurrence of nuclear
deformation in 39 Na, as it induces more stability to
the nuclear binding. 39 Na could be particle-bound as
its ground state is deformed, suggesting the loss of theN = 28 magicity at sodium. This interpretation is supported by the recent state-of-the-art large-scale shellmodel calculation with ab initio eﬀective NN interactions,6) which reproduces the stability of 39 Na as wellas the neutron dripline at ﬂuorine and neon. The calculation reveals that the quadrupole deformation plays
a key role in nuclear binding in this region and thus indetermining the location of the neutron dripline.

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)

References
1) D. S. Ahn et al., Phys. Rev. Lett. 123, 212501 (2019).
2) D. S. Ahn et al., Phys. Rev. Lett. 129, 212502 (2022).
3) M. Notani et al., Phys. Lett. B 542, 49 (2002).
4) T. Kubo, Nucl. Instrum. Methods Phys. Res. Sect. B
204, 97 (2003).
5) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 03C003(2012).
6) N. Tsunoda et al., Nature 587, 66 (2020).

2- S8 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Study of the N = 32 and N = 34 shell gap for Ti and V
by the ﬁrst high-precision multireﬂection time-of-ﬂight
mass measurements at BigRIPS-SLOWRI†
S. Iimura,∗1,∗2,∗3,∗4 M. Rosenbusch,∗3 A. Takamine,∗1 Y. Tsunoda,∗5 M. Wada,∗3 S. Chen,∗6 D. S. Hou,∗7
W. Xian,∗6 H. Ishiyama,∗1 S. Yan,∗8 P. Schury,∗3 H. Crawford,∗9 P. Doornenbal,∗1 Y. Hirayama,∗3 Y. Ito,∗10
S. Kimura,∗1 T. Koiwai,∗11,∗1 T. M. Kojima,∗1 H. Koura,∗10 J. Lee,∗6 J. Liu,∗6,∗7 S. Michimasa,∗12 H. Miyatake,∗3
J. Y. Moon,∗13 S. Naimi,∗1 S. Nishimura,∗1 T. Niwase,∗3,∗1,∗14 A. Odahara,∗2 T. Otsuka,∗11,∗1,∗10 S. Paschalis,∗15
M. Petri,∗15 N. Shimizu,∗5 T. Sonoda,∗1 D. Suzuki,∗1 Y. X. Watanabe,∗3 K. Wimmer,∗11,∗16,∗1 and H. Wollnik∗17†

Condensed from the article in Phys. Rev. Lett. 130, 012501(2023)∗1 RIKEN Nishina Center∗2 Department of Physics, Osaka University∗3 Wako Nuclear Science Center (WNSC), IPNS, KEK∗4 Department of Physics, Rikkyo University∗5 Center for Computational Sciences, University of Tsukuba∗6 Department of Physics, University of Hong Kong
∗7 Institute of Modern Physics, Chinese Academy of Sciences∗8 IAESPC, Jinan University∗9 Nuclear Structure Group, Lawrence Berkeley National Laboratory∗10 Advanced Science Research Center, Japan Atomic Energy
Agency∗11 Department of Physics, University of Tokyo∗12 Center for Nuclear Study, University of Tokyo∗13 Rare Isotope Science Project, Institute for Basic Science∗14 Department of Physics, Kyushu University∗15 School of Physics, University of York
∗16 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗17 New Mexico State University- S9 -

cantly improved to the order of 10 keV or below. The
newly determined masses of 58 Ti and 59 V were foundto deviate from previously measured values, where—
especially for 58 Ti—an increased binding energy has
been measured. Figure 1 shows the newly determined
two-neutron shell gap of N = 34 isotones (red line) deduced directly from masses. Literature values suggested
an enhancement of the gap with Ti and V, whereas
there is no gap found in this study, indicating that theN = 34 shell gap is a unique feature of Ca.
     

Masses of neutron-rich isotopes with N ≥ 32 between
Ca and Ni have recently been studied intensely as valuable probes of the complex nuclear structure. For Ca
isotopes, a pronounced reduction of tensor-interactioneﬀects1) due to the decrease of proton valence particles occupying the πf7/2 orbits has been conﬁrmed by
the discovery of two new magic neutron numbers, i.e.,
N = 32 and N = 34. In the Ti isotope chain, a shell
gap at N = 32 had been conﬁrmed, and the collective
behavior due to a νg9/2 level intrusion was found in theregion close to N = 40 in several studies.2–4) As for the
N = 34 shell gap, previous mass measurements havesuggested the existence of a pronounced shell gap withmoderate uncertainties.5,6) However, a new study has
revealed the vanishing of the magicity.
The experiment was performed at RIKEN RI Beam
Factory (RIBF), which is operated by an international
collaboration team primarily from RIKEN Nishina
Center and KEK Wako Nuclear Science Center. Radioactive isotopes (RIs) have been produced by the fragmentation of a 345 MeV/nucleon Zn beam with a Be
target and delivered to the ZD MRTOF system7) for
the ﬁrst time as part of the SLOWRI project. The newsetup has been located downstream of the ZeroDegree
spectrometer following the BigRIPS separator.
During the ﬁrst commission, the masses of 15
neutron-rich nuclei have been measured with high precision and accuracy. Among the results, the mass precisions of 55 Sc, 56, 58 Ti, and 56–59 V have been signiﬁ-

3

𝑁𝑁 𝑁 𝑁𝑁 

2
1


literature values
mlit. (N − 2) − 2mexp. (N ) + mlit. (N + 2)
mlit. (N − 2) − 2mexp. (N ) + mexp. (N + 2)




     Fig. 1. Two-neutron shell gaps for N = 34 isotones including the new mass data. Data are from AME2020 withrecent measurements (black open circles) and our experimental values (partly ﬁlled red circles).

In order to understand the observed results, we performed new Monte Carlo shell model calculations using
the A3DA-m Hamiltonian8) and compared the resultswith conventional shell model calculations, which exclude the higher (νg9/2 , νd5/2 ) orbits. The comparison
indicates that the reduction of the shell gap in Ti isrelated to partial occupation of the higher orbitals forthe outer two valence neutrons at N = 34.
References
1) T. Otsuka et al., Rev. Mod. Phys. 92, 015002 (2020).
2) K. Wimmer et al., Phys. Lett. B 792, 16 (2019).
3) M. Cortés et al., Phys. Lett. B 800, 135071 (2020).
4) E. Leistenschneider et al., Phys. Rev. Lett. 120, 062503(2018).
5) Z. Meisel et al., Phys. Rev. C 101, 052801(R) (2020).
6) S. Michimasa et al., Phys. Rev. Lett. 125, 122501 (2020).
7) M. Rosenbusch et al., Nucl. Instrum. Methods Phys. Res.
A 1047, 167824 (2023).
8) Y. Tsunoda et al., Phys. Rev. C 89, 031301(R) (2014).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Charge-changing cross sections for 42–51 Ca and eﬀect ofcharged-particle evaporation induced by neutron removal reactions†
M. Tanaka,∗1,∗2 M. Takechi,∗3 A. Homma,∗3 A. Prochazka,∗4 M. Fukuda,∗2 D. Nishimura,∗5,∗1 T. Suzuki,∗6
T. Moriguchi,∗7,∗1 D. S. Ahn,∗1 A. Aimaganbetov,∗8,∗9 M. Amano,∗7 H. Arakawa,∗6 S. Bagchi,∗4,∗10,∗11,∗12K. H. Behr,∗4 N. Burtebayev,∗8,∗13 K. Chikaato,∗3 H. Du,∗2 T. Fujii,∗6 N. Fukuda,∗1 H. Geissel,∗4 T. Hori,∗2
S. Hoshino,∗3 R. Igosawa,∗6 A. Ikeda,∗3 N. Inabe,∗1 K. Inomata,∗6 K. Itahashi,∗1 T. Izumikawa,∗14 D. Kamioka,∗7
N. Kanda,∗3 I. Kato,∗6 I. Kenzhina,∗8,∗13 Z. Korkulu,∗15,∗1 Y. Kuk,∗8,∗9 K. Kusaka,∗1 K. Matsuta,∗2
M. Mihara,∗2 E. Miyata,∗3 D. Nagae,∗1,∗16 S. Nakamura,∗2 M. Nassurlla,∗8,∗13 K. Nishimuro,∗6 K. Nishizuka,∗3
K. Ohnishi,∗2 M. Ohtake,∗1 T. Ohtsubo,∗3 S. Omika,∗6 H. J. Ong,∗17,∗1 A. Ozawa,∗7,∗1 H. Sakurai,∗1,∗18
C. Scheidenberger,∗4 Y. Shimizu,∗1 T. Sugihara,∗2 T. Sumikama,∗1 H. Suzuki,∗1 S. Suzuki,∗7 H. Takeda,∗1
Y. Tanaka,∗2 Y. K. Tanaka,∗4 I. Tanihata,∗17,∗19 T. Wada,∗3 K. Wakayama,∗6 S. Yagi,∗2 T. Yamaguchi,∗6
R. Yanagihara,∗2 Y. Yanagisawa,∗1 K. Yoshida,∗1 and T. K. Zholdybayev∗8,∗13†

Condensed from the article in Phys. Rev. C 106, 014617(2022)∗1 RIKEN Nishina Center∗2 Department of Physics, Osaka University∗3 Department of Physics, Niigata University∗4 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗5 Department of Physics, Tokyo City University∗6 Department of Physics, Saitama University∗7 Department of Physics, University of Tsukuba∗8 Institute of Nuclear Physics∗9 L. N. Gumilyov Eurasian National University∗10 Astronomy and Physics Department, Saint Mary’s University∗11 Jutus Liebig University∗12 Indian Institute of Technology (Indian School of Mines)
Dhanbad∗13 Al-Farabi Kazakh National University∗14 Institute for Research Promotion, Niigata University∗15 Center for Exotic Nuclear Studies, Institute for Basic Science∗16 RCSHE, Kyushu University∗17 Research Center for Nuclear Physics (RCNP), Osaka University∗18 Department of Physics, University of Tokyo∗19 School of Physics and Nuclear Energy Engineering, Beihang
University

Present data

1450

4)

Existing dataσ~ CC
σ~ CC + σevap

1400
σCC (mb)

The point-proton radius rp of an atomic nucleus
is generally determined by optical isotope shift andmuonic X-ray measurements. However, these experimental methods are limited to certain elements. Alternatively, “alternative methods, particularly for unstable
nuclei, have been proposed to overcome this limitation,such as electron scattering using SCRIT at RIBF.”1) A
charge-changing cross-section σCC is one of the possible quantities to extract the rp of unstable nuclei. Recently, the σCC measurement has been utilized to extract the rp of light-mass nuclei.2,3) However, some σCCdata for medium-mass nuclides around Ca deviate fromthe Glauber-like models adopted in previous studies.4)
To clarify the relationship between σCC and rp , σCCon 12 C for 42–51 Ca at around 280 MeV/nucleon wasmeasured at RIBF. The present data are shown in
Fig. 1. For comparison, the Glauber-like calculation
adopted in previous studies2–4) was performed using theexisting rp value4) as an input. The calculated values(σ̃CC : black dashed line), which reﬂect the trend of experimental rp ,5) show a signiﬁcant discrepancy from theexperimental values of stable nuclei around 42 Ca.
This discrepancy was found to correlate with the

1350
1300
1250
1200
35

40

45

50

55

A
Fig. 1. Mass number (A) dependence of σCC for Ca isotopes
on 12 C at 280 MeV/nucleon.

proton separation energy. From this ﬁgure, the crosssection of the charged-particle evaporation induced by
the neutron removal, σevap , was introduced based on
the abrasion-ablation scheme in addition to σ̃CC . The
calculated values of σ̃CC + σevap (solid red line) reproduced well in the experimental data. This calculation
also systematically explained the existing σCC data forother isotopic chains from C to Fe with a standard deviation of 1.6%.
Figure 1 also shows that the eﬀect of σevap becomes
negligibly small in the neutron-rich region. It was foundthat a 1% accuracy of σCC has the potential to determine rp with 0.9% accuracy in neutron-rich Ca isotopes(A ≥ 51).
References
1) T. Tsukada et al., Phys. Rev. Lett. 118, 262501 (2017).
2) T. Yamaguchi et al., Phys. Rev. Lett. 107, 032502(2011).
3) S. Bagchi et al., Phys. Lett. B 790, 251 (2019).
4) S. Yamaki et al., Nucl. Instrum. Methods Phys. Res. B
317, 774 (2013).
5) R. F. Garcia Ruiz et al., Nat. Phys. 12, 594 (2016).

- S10 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Probing optimal reaction energy for synthesis of element 119 from51
V+248 Cm reaction with quasielastic barrier distribution
measurement†
M. Tanaka,∗1,∗2,∗3 P. Brionnet,∗3 M. Du,∗4 J. Ezold,∗4 K. Felker,∗4 B. J. P. Gall,∗5 S. Go,∗1,∗2,∗3
R. K. Grzywacz,∗4,∗6 H. Haba,∗3 K. Hagino,∗7 S. Hogle,∗4 S. Ishizawa,∗3,∗8 D. Kaji,∗3 S. Kimura,∗3 T. T. King,∗6
Y. Komori,∗3 R. K. Lemon,∗3,∗9 M. G. Leonard,∗3,∗9 K. Morimoto,∗3 K. Morita,∗1,∗2,∗3 D. Nagae,∗1,∗2,∗3
N. Naito,∗3,∗10 T. Niwase,∗1,∗3 B. C. Rasco,∗4 J. B. Roberto,∗4 K. P. Rykaczewski,∗4 S. Sakaguchi,∗1,∗2,∗3
H. Sakai,∗3 Y. Shigekawa,∗3 D. W. Stracener,∗4 S. VanCleve,∗4 Y. Wang,∗3 K. Washiyama,∗2 and T. Yokokita∗3†

Condensed from the article in J. Phys. Soc. Jpn. 91, 084201(2022)∗1 Department of Physics, Kyushu University∗2 Research Center for Superheavy Elements, Kyushu University∗3 RIKEN Nishina Center∗4 Oak Ridge National Laboratory∗5 IPHC, CNRS, Université de Strasbourg∗6 Department of Physics and Astronomy, University of Tennessee∗7 Department of Physics, Kyoto University∗8 Graduate School of Science and Engineering, Yamagata University∗9 Department of Nuclear Physics and Accelerator Applications, Australian National University∗10 Graduate School for Science, Kyushu University- S11 -

R(E) = dσQE / dσRuth.

1.0

(a)

0.8
0.6
0.4
0.2

51

V+

248

Cm

Exp. datadσQE / dσRuth.
Upper limit

0.0
0.20
0.15
−1

D(E) [MeV ]At RIKEN, there is a search for element 119 using
a 51 V + 248 Cm hot fusion reaction. The optimal reaction energy of this reaction system is unknown owing to wide variations in theoretical predictions. A
method has been developed to estimate the optimal energy from the quasielastic (QE) barrier distribution.1)
In this study, the QE barrier distribution of the 51 V +248
Cm reaction was measured using the gas-ﬁlled recoil ion separator GARIS-III at the recently upgradedfacility, SRILAC,2) and the optimal reaction energy
for synthesizing element 119 from the 51 V + 248 Cm
reaction was estimated.
The experimental excitation function of the QE
backscattering cross section σQE relative to the
Rutherford cross section σRuth. , denoted as R(E), forthe 51 V + 248 Cm reaction is shown in Fig. 1(a) with thesingle- and coupled-channel calculations. Figure 1(b)shows the barrier distribution, D(E), derived from theenergy derivative of Fig. 1. Both the experimental
trends of R(E) and D(E) are explained by the coupledchannel calculation, indicating a signiﬁcant eﬀect of
the rotational excitation of the deformed 248 Cm.
Aiming to estimate the optimal energy for element119 synthesis, the average Coulomb barrier height,
B0 , for the 51 V + 248 Cm reaction was derived fromthe present data to be 225.6(2) MeV (closed arrow in
Fig. 1). The side-collision energy, Bside , which is considered to be favorable for forming a compound nucleus, was also determined to be 233.0(2) MeV (openarrow) by considering the deformation of 248 Cm. By
evaluating the relation between Bside and the optimalenergy for maximizing the evaporation-residue cross(b)Single-channel calc.
Coupled-channel calc.

0.10
0.05
0.00
B0 Bside
180

200

220

240

Ec.m. [MeV]Fig. 1. (a) R(E) and (b) D(E) as a function of the centerof-mass energy Ec.m. . The dashed and solid lines represent the single- and coupled-channel calculations, respectively.

section in the 48 Ca + 248 Cm system, the optimal energy for the 248 Cm(51 V, 3;4n)296;295 119 reaction was
estimated to be 234.8 ± 1.8 MeV. Using this deduced
reaction energy, an experiment for the synthesis of element 119 at RIKEN is currently underway.
References
1) T. Tanaka et al., Phys. Rev. Lett. 124, 052502 (2020).
2) H. Sakai et al., Eur. Phys. J. A 58, 238 (2022).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

β-delayed one and two neutron emission probabilities south-east of132
Sn and the odd-even distribution of the r-process abundances†V. H. Phong,∗1,∗2 S. Nishimura,∗1 G. Lorusso,∗1,∗3,∗4 T. Davinson,∗5 A. Estrade,∗6 O. Hall,∗5 T. Kawano,∗7
J. Liu,∗1,∗8 F. Montes,∗9 N. Nishimura,∗1,∗10 R. Grzywacz,∗11 K. P. Rykaczewski,∗12 J. Agramunt,∗13
D. S. Ahn,∗1,∗14 A. Algora,∗13,∗25 J. M. Allmond,∗12 H. Baba,∗1 S. Bae,∗14 N. T. Brewer,∗11,∗12 C. G. Bruno,∗5
R. Caballero-Folch,∗15 F. Calviño,∗16 P. J. Coleman-Smith,∗17 G. Cortes,∗16 I. Dillmann,∗15,∗18
C. Domingo-Pardo,∗13 A. Fijalkowska,∗19 N. Fukuda,∗1 S. Go,∗1 C. J. Griffin,∗5 J. Ha,∗1,∗20
L. J. Harkness-Brennan,∗21 T. Isobe,∗1 D. Kahl,∗5,∗22 L. H. Khiem,∗23,∗24 G. G. Kiss,∗1,∗25 A. Korgul,∗19
S. Kubono,∗1 M. Labiche,∗17 I. Lazarus,∗17 J. Liang,∗26 Z. Liu,∗27,∗28 K. Matsui,∗1,∗29 K. Miernik,∗19 B. Moon,∗14
A. I. Morales,∗13 P. Morrall,∗17 N. Nepal,∗6 R. D. Page,∗21 M. Piersa-Silkowska,∗19 V. F. E. Pucknell,∗17
B. C. Rasco,∗12 B. Rubio,∗13 H. Sakurai,∗1,∗29 Y. Shimizu,∗1 D. W. Stracener,∗12 T. Sumikama,∗1 H. Suzuki,∗1
J. L. Tain,∗13 H. Takeda,∗1 A. Tarifeño-Saldivia,∗13,∗16 A. Tolosa-Delgado,∗13 M. Wolińska-Cichocka,∗30
P. J. Woods,∗5 and R. Yokoyama∗11,∗31
The nucleosynthesis of elements around the second rprocess abundance peak has attracted considerable interest recently, with metal-poor star observations of elemental and isotopic abundances1,2) providing important clues on the sensitivity of the peak to the r-processenvironments. To connect such observations to the astrophysical models and ultimately derive the r-process
conditions, knowledge of the nuclear properties of thesecond r-process peak radioactive progenitors is essential.
After r-process freezeout, final r-process abundancesof the second peak originate from a network of compet†

Condensed from the article in Phys. Rev. Lett. 129, 172701(2022)∗1 RIKEN Nishina Center∗2 Vietnam National University, Hanoi∗3 National Physical Laboratory, Teddington∗4 Department of Physics, University of Surrey∗5 School of Physics and Astronomy, University of Edinburgh∗6 Department of Physics, Central Michigan University∗7 Theoretical Division, Los Alamos National Laboratory∗8 Department of Physics, University of Hong Kong
∗9 National Superconducting Cyclotron Laboratory∗10 Astrophysical Big-Bang Laboratory∗11 University of Tennessee, Knoxville∗12 Physics Division, Oak Ridge National Laboratory∗13 Instituto de Fı́sica Corpuscular, CSIC-University of Valencia∗14 Center for Exotic Nuclear Studies, Institute for Basic Science∗15 TRIUMF, Vancouver∗16 Universitat Politecnica de Catalunyan∗17 STFC Daresbury Laboratory∗18 Department of Physics and Astronomy, University of Victoria∗19 Faculty of Physics, University of Warsaw∗20 Department of Physics and Astronomy, Seoul National University∗21 Department of Physics, University of Liverpool∗22 Extreme Light Infrastructure – Nuclear Physics, Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering∗23 Institute of Physics, VAST
∗24 Graduate University of Science and Technology, VAST
∗25 Institute for Nuclear Research (ATOMKI)∗26 Department of Physics and Astronomy, McMaster University∗27 Institute of Modern Physics, Chinese Academy of Sciences∗28 School of Nuclear Science and Technology, University of Chinese Academy of Sciences∗29 Department of Physics, University of Tokyo∗30 Heavy Ion Laboratory, University of Warsaw∗31 Center for Nuclear Study, University of Tokyo

ing reactions including the neutron capture, photodisintegration, fission contribution and β-delayed neutron
emission. The latter has been the main focus of ourexperiment carried out within the BRIKEN project3)
at RIBF, where β-delayed one and two neutron emission probabilities (P1n and P2n ) of neutron-rich nuclei south-east of 132 Sn have been measured. The systematic of the measured P1n and P2n values, shownin Fig. 1, highlighted the nuclear shell effects arounddoubly-magic 132 Sn. Our results also provided important benchmarks for the recent macroscopic-microscopic
and self-consistent global model, including the statisticaltreatment of neutron and γ emission.4,5) Direct impactsof the measured P1n and P2n on the odd-even staggering of the final r-process abundance around the second
r-process peak were demonstrated. The observed oddmass isotopic fractions of Ba in metal-poor stars2) were
found to be better reproduced by using our data.

Fig. 1. Systematics of measured P1n (top panels) and P2ncompared with theoretical calculations.4,5)

References
1) I. U. Roederer et al., Astrophys. J. Suppl. Ser. 260, 27(2022).
2) C. Wenyuan et al., Astrophys. J. 854, 131 (2018).
3) I. Dillmann et al., Nucl. Phys. News 28, 28 (2018).
4) T. Kawano et al., Phys. Rev. C 78, 054601 (2008).
5) F. Minato et al., Phys. Rev. C 104, 044321 (2021).

- S12 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Various nuclear structures in 140 Xe studied by β decayof ground and isomeric states in 140 I†
A. Yagi,∗1,∗2 A. Odahara,∗1 H. Nishibata,∗1,∗2,∗3 R. Lozeva,∗4,∗5 C. -B. Moon,∗6,∗7 S. Nishimura,∗2
K. Yoshida,∗8 and N. Yoshinaga∗9 for the EURICA Collaboration
Nuclear-shape transition with the increase of neutron and/or proton numbers is one of the most important subjects to disentangle competition between
single-particle and collective structures in the ﬁnite
quantum many-body system. The neutron-rich N =86 isotope 140 Xe, located northeast of a doubly-magic
nucleus 132 Sn, was investigated by β-γ spectroscopy,
as one of experiments in the Euroball RIKEN Cluster
Array (EURICA) project.1,2)
Neutron-rich Sb, Te, I, Xe, and Cs isotopes withA ∼ 140 were produced by in-ﬂight ﬁssion of a 345MeV/nucleon 238 U beam with an average intensity of
5 particle nA. These isotopes were transported basedon in-ﬂight separation technique by using BigRIPS
separator and ZeroDegree spectrometer3) up to thelast focal plane (F11) with setting magnetic rigidity(Bρ) for 142 Te52+ . The isotopes were implanted into
a position sensitive active stopper, Wide-range Active
Silicon Strip Stopper Array for Beta and Ion detection (WAS3ABi), which consists of ﬁve double-sided Si
strip detectors (DSSSDs). In addition, the WAS3ABi
was used as a β counter. Parent β-decaying nuclei
were identiﬁed by position correlation of the implanted
fragments with information of particle identiﬁcation(PI) and the detected β rays in WAS3ABi. Gammarays emitted after the β decay were detected by a γray detector array, EURICA, which consists of twelve
cluster-type high-purity Ge detectors with seven crystals. To study the β decay of 140 I in this work, twodata sets with PI of hydrogen-like 140 I52+ and fully
stripped 140 Te52+ were analyzed. Namely, the parent
nucleus 140 I was produced by two diﬀerent reactionsof (i) direct in-ﬂight ﬁssion at primary target and (ii)β decay of 140 Te inside WAS3ABi. Relative intensityof γ ray was obtained by using γ-ray photo-peak eﬃciency, which was simulated using the Geant4 code for
the EURICA Ge array with distribution of the 140 I and140
Te particles on ﬁve DSSSD detectors in WAS3ABi.
Two β-decay isomers in 140 I are newly found in the
study of two diﬀerent β decays of 140 I with PI of 140 I
†
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Condensed from the article in Phys. Rev. C 105, 044325(2022)
Department of Physics, Osaka University
RIKEN Nishina Center
Department of Physics, Kyushu University
IPHC, CNRS, IN2P3 and University of Strasbourg
Université Paris-Saclay, IJCLab, CNRS/IN2P3
Department of Display Engineering, Hoseo University
Center for Exotic Nuclear Studies, Institute for Basic Science
Department of Physics, Kyoto University
Department of Physics, Saitama University- S13 -

(140 I → 140 Xe) and 140 Te (140 Te → 140 I → 140 Xe).
Half-lives of the β decays of the ground state (g.s.),
low-spin isomer (LSI), and high-spin isomer (HSI) aredetermined to be 0.38(2), 0.91(5), and 0.47(4) sec,
respectively, by the analysis of time-diﬀerence (implanted particle and β-decay event) spectra gated by
the γ rays in 140 Xe. Decay schemes of the β decay of
the HSI and of the mixed β decays of the g.s. and the
LSI in 140 I to 140 Xe are constructed using the information on γ-ray coincidence relation and γ-ray intensity.
Nuclear structures of the low-lying states in 140 Xe
are compared between the experimental results andtwo theoretical calculations based on the largescale shell model and the deformed Skyrme HartreeFock-Bogoliubov (HFB) plus deformed quasiparticlerandom-phase approximation (QRPA), as shown in
Fig. 1. Low-lying states can be classiﬁed into (a)g.s. band, (b) (quasi-)γ-band, and (c) octupole collective states. Possible candidates for the (quasi-)γ-band
members of 2+ and 4+ and the octupole collective 1−state are proposed in 140 Xe. This work demonstrates
that in the low-lying states of 140 Xe, coexistence of nuclear structures, such as vibrational nature with prolate collectivity, large-γ collectivity (γ softness), andoctupole-vibrational nature, could appear due to fourvalence protons and four valence neutrons being coupled to the doubly-magic nucleus 132 Sn.
Ex [keV]
3500

Kπ=3-

3000
Kπ=2-

2500

(c)

(b) 5- 1772 1759
5+ 1573
6+ 1417 (4+) 1399 3- 1513 1570
3+ 1304(2+) 1152
4+ 834
(a)

1000
500

2+ 3770+2103
1964 2000
1940
1788
1710
1559
1498 1500

00experimental result

1+

(a)
6+

(c)
(b) 5- 3+0+

5+
4+
3+

4+

3-

1+
4++
1 +
0+ 3+
2

2-- 1
3
4-

-

Kπ=2+
Kπ=0+

Kπ=1-

2+
Kπ=0-

2+
0+

shell model

deformed SkyrmeHFB+QRPA (SkM*)

Fig. 1. Experimental low-lying states are compared tothose calculated in the shell model and the deformed
Skyrme-HFB + QRPA (SkM∗ ).

References
1) S. Nishimura, Prog. Theor. Exp. Phys. 2012, 03C006(2012).
2) P. -A. Söderström et al., Nucl. Instrum. Methods Phys.
Res. B 317, 649 (2013).
3) T. Kubo et al., Prog. Theor. Exp. Phys. 2012, 03C003(2012).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Observation of a correlated free four-neutron system†
M. Duer,∗1 T. Aumann,∗1,∗2,∗3 R. Gernhäuser,∗4 V. Panin,∗2,∗5 S. Paschalis,∗1,∗6 D. M. Rossi,∗1 N. L. Achouri,∗7
D. Ahn,∗5 H. Baba,∗5 C. A. Bertulani,∗8 M. Böhmer,∗4 K. Boretzky,∗2 C. Caesar,∗1,∗2,∗5 N. Chiga,∗5 A. Corsi,∗9
D. Cortina-Gil,∗10 C. A. Douma,∗11 F. Dufter,∗4 Z. Elekes,∗12 J. Feng,∗13 B. Fernández-Domı́nguez,∗10
U. Forsberg,∗6 N. Fukuda,∗5 I. Gasparic,∗1,∗5,∗14 Z. Ge,∗5 J. M. Gheller,∗9 J. Gibelin,∗7 A. Gillibert,∗9
K. I. Hahn,∗15,∗16 Z. Halász,∗12 M. N. Harakeh,∗11 A. Hirayama,∗17 M. Holl,∗1 N. Inabe,∗5 T. Isobe,∗5
J. Kahlbow,∗1 N. Kalantar-Nayestanaki,∗11 D. Kim,∗16 S. Kim,∗1,∗16 T. Kobayashi,∗18 Y. Kondo,∗17 D. Körper,∗2
P. Koseoglou,∗1 Y. Kubota,∗5 I. Kuti,∗12 P. J. Li,∗19 C. Lehr,∗1 S. Lindberg,∗20 Y. Liu,∗13 F. M. Marqués,∗7
S. Masuoka,∗21 S. Masuoka,∗21 M. Matsumoto,∗17 J. Mayer,∗22 K. Miki,∗1,∗18 B. Monteagudo,∗7 T. Nakamura,∗17
T. Nilsson,∗20 A. Obertelli,∗1,∗9 N. A. Orr,∗7 H. Otsu,∗5 S. Y. Park,∗15,∗16 M. Parlog,∗7 P. M. Potlog,∗23
S. Reichert,∗4 A. Revel,∗7,∗9,∗24 A. T. Saito,∗17 M. Sasano,∗5 H. Scheit,∗1 F. Schindler,∗1 S. Shimoura,∗21
H. Simon,∗2 L. Stuhl,∗16,∗21 H. Suzuki,∗5 D. Symochko,∗1 H. Takeda,∗5 J. Tanaka,∗1,∗5 Y. Togano,∗17 T. Tomai,∗17
H. T. Törnqvist,∗1,∗2 J. Tscheuschner,∗1 T. Uesaka,∗5 V. Wagner,∗1 H. Yamada,∗17 B. Yang,∗13 L. Yang,∗21
Z. H. Yang,∗5 M. Yasuda,∗17 K. Yoneda,∗5 L. Zanetti,∗1 J. Zenihiro,∗5,∗25 and M. V. Zhukov∗20
The high impact potential of multi-neutron systems
has led to many experimental searches for such isolated
systems starting in the early 60 s, with in particular, thefour-neutron system. Till date, only a few indications of
its existence have been found.1)
This study used the quasi-elastic knockout reaction
8
He(p, pα) at maximum momentum transfer, removing
the α-core from 8 He as fast as possible, to ensure a recoilless production of the 4n as spectators.
The experiment was conducted at SAMURAI, wherea 156 MeV/nucleon 8 He beam was transported to aliquid-hydrogen target. From the combined selection of
charged particles in the reaction, the energy spectrumof the 4n system was reconstructed via the missing-mass
method, as shown in Fig. 1. Two components are observed: a pronounced peak at low energy which experimentally has a resonance-like structure, and a wide distribution at higher energies attributed to a non-resonant
continuum response.2) As the non-resonant part cannot†

Condensed from the article in Nature 606, 678 (2022)
Institut für Kernphysik, Technische Universität Darmstadt∗2 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗3 Helmholtz Forschungsakademie Hessen für FAIR
∗4 Physik Department, Technische Universität München∗5 RIKEN Nishina Center∗6 Department of Physics, University of York∗7 Laboratoire de Physique Corpusculaire de Caen
∗8 Department of Physics, Texas A&M University∗9 IRFU, CEA, Université Paris-Saclay∗10 Molecular and Nuclear Physics, USC∗11 Faculty of Science and Engineering, University of Groningen∗12 Hungarian Academy of Sciences, Eötvös Loránd Research Network∗13 Department of Physics, Peking University∗14 Division of Experimental Physics, Rudjer Bošković Institute∗15 Department of Physics, Ewha Womans University∗16 Korea Basic Science Institute∗17 Department of Physics, Tokyo Institute of Technology∗18 Department of Physics, Tohoku University∗19 Department of Physics, University of Hong Kong
∗20 Department of Physics, Chalmers University of Technology∗21 Center for Nuclear Study, University of Tokyo∗22 Institut für Kernphysik, Universität zu Köln∗23 Department of Physics, Institute of Space Sciences∗24 GANIL, CEA Caen
∗25 Department of Physics, Kyoto University∗1

Fig. 1. Missing-mass spectrum of the 4n system.

explain the sharp low-energy peak, the energy and widthof the resonance-like structure was determined assuming a Breit-Wigner shape as Er = 2.37 ± 0.58 MeV andΓ = 1.75 ± 0.40 MeV, respectively, with a striking signiﬁcance level.
From theoretical perspective there is no consensus
among the diﬀerent studies. While some predict a lowenergy resonance,3) others exclude this possibility4) andeven predict that a low-energy structure can appear asa consequence of neutron’s ﬁnal-state interaction, andthe reaction mechanism.5) Whether our observation is
attributed to a tetra-neutron correlation or other correlations between the neutrons in the ﬁnal state, needs
to be clariﬁed by ab initio theories accounting fully forthe continuum. Next-generation experiments, foreseen
at SAMURAI, using diﬀerent reaction mechanisms anddetecting the four neutrons in coincidence will shed lighton the properties of the four-neutron system and the origin of the low-energy peak.
References
1) F. M. Marqués et al., Eur. Phys. J. A 57, 105 (2021).
2) L. V. Grigorenko et al., Eur. Phys. J. A 19, 187 (2004).
3) S. Gandolﬁ et al., Phys. Rev. Lett. 118, 232501 (2017).
4) E. Hiyama et al., Phys. Rev. C 93, 044004 (2016).
5) R. Lazauskas et al., arXiv:2207.07575.

- S14 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Isoscaling in central Sn + Sn collisions at 270 MeV/nucleon††

Condensed from the article in Eur. Phys. J. A 58, 201 (2022)
Department of Physics, Korea University∗2 Facility for Rare Isotope Beams, Michigan State University∗3 Department of Physics, Michigan State University∗4 RIKEN Nishina Center∗5 Department of Physics, Kyoto University∗6 Department of Physics, Tohoku University∗7 Instituto de Fı́sica, Universidade Federal do Rio de Janeiro∗8 Departamento de Engenharia Nuclear, Universidade Federal
de Minas Gerais∗9 Institut für Kernphysik, Technische Universität Darmstadt∗10 GSI Helmholtzzentrum für Schwerionenforschung GmbH∗11 Faculty of Physics, Jagiellonian University∗12 Division of Experimental Physics, Rudjer Boskovic Institute∗13 Department of Physics, Rikkyo University∗14 Department of Life and Environmental Agricultural Sciences,
Tottori University∗15 Rare Isotope Science Project, Institute for Basic Science∗16 Department of Physics, Tokyo Institute of Technology∗17 Institute of Nuclear Physics PAN∗18 Cyclotron Institute, Texas A&M University∗19 Nikhef National Institute for Subatomic Physics∗20 Department of Physics, Tsinghua University∗21 Department of Chemistry, Texas A&M University∗1

y = 0 - 0.40

Z =1

α = 0.29

R 21

Experimental study on the early stage of heavy-ion
collision is challenging as excited fragments produced
from the collision decay into lighter particles before they
are detected. The nuclear isoscaling phenomenon is a
useful tool as the ratio of yields from two different reactions is weakly affected by the fragment de-excitation
process.1)
Rare isotope Tin beams 132 Sn and 108 Sn were produced from RIBF and impinged onto the isotopically enriched Tin targets. Hydrogen and helium isotopes weredetected in SπRIT time projection chamber2) placed inside the SAMRURAI dipole magnet.3) Particles wereidentified from the magnetic rigidity and mean energy
loss.4) Most central events with impact parameter b <1.5 fm and mid rapidity range y0 = 0–0.4 are chosen forthis analysis.
The yield ratios between two systems R21 = Y(132 Sn+ 124 Sn)/Y(108 Sn + 112 Sn) as a function of pT /A are
shown in Fig. 1. Given that the collision systems arethermally equilibrated, R21 follow the isoscaling law
R21 = C exp(αN + βZ) where α and β are the fit parameters. Empirically, α and β have similar values with
opposite signs, therefore, particles with the same (N −Z)
value show similar R21 values. Figure 1 show isoscaling
effect for pT < 280 MeV/c (left side of vertical dashedline). In this region, the isoscaling fit gives α = 0.29 andR 21

J. W. Lee,∗1 M. B. Tsang,∗2,∗3 C. Y. Tsang,∗2,∗3 R. Wang,∗2 J. Barney,∗2,∗3 J. Estee,∗2,∗3 T. Isobe,∗4
M. Kaneko,∗4,∗5 M. Kurata-Nishimura,∗4 W. G. Lynch,∗2,∗3 T. Murakami,∗4,∗5 A. Ono,∗6 S. R. Souza,∗7,∗8
D. S. Ahn,∗4 L. Atar,∗9,∗10 T. Aumann,∗9,∗10 H. Baba,∗4 K. Boretzky,∗10 J. Brzychczyk,∗11 G. Cerizza,∗2
N. Chiga,∗4 N. Fukuda,∗4 I. Gasparic,∗12,∗4,∗9 B. Hong,∗1 A. Horvat,∗9,∗10 K. Ieki,∗13 N. Ikeno,∗14 N. Inabe,∗4
G. Jhang,∗2 Y. J. Kim,∗15 T. Kobayashi,∗6,∗4 Y. Kondo,∗16,∗4 P. Lasko,∗17 H. S. Lee,∗15 Y. Leifels,∗10 J. L
 ukasik,∗17
∗2,∗3
∗18
∗2
∗16,∗4∗4,∗5J. Manfredi,A. B. McIntosh,
P. Morfouace, T. Nakamura,
N. Nakatsuka,
S. Nishimura,∗4
∗4
∗17
∗11
∗9
∗4
∗2
H. Otsu, P. Pawlowski,
K. Pelczar,
D. Rossi, H. Sakurai, C. Santamaria, H. Sato,∗4 H. Scheit,∗9
∗2
∗4
∗10
R. Shane, Y. Shimizu, H. Simon,
A. Snoch,∗19 A. Sochocka,∗11 T. Sumikama,∗4 H. Suzuki,∗4 D. Suzuki,∗4∗4∗2
H. Takeda, S. Tangwancharoen, Y. Togano,∗13,∗4 Z. G. Xiao,∗20 S. J. Yennello,∗18,∗21 and Y. Zhang∗20

β = -0.23

1

1.5

Z =2
p /A < 280 MeV/c
T

0

1

2

N

1

Exp.
AMD

0.5
0

p

100

d

200

t

3

He

300

4

He

400

500

600

p /A (MeV/c)
T

Fig. 1. The yield ratio R21 between two systems 132 Sn +124
Sn and 108 Sn + 112 Sn. Experimental data (markers)
are compared with AMD (shaded area). Inner panel:
Isoscaling ﬁt for pT /A < 280 MeV/c.

β = −0.23 (inner panel of Fig. 1). On the other hand,
the triton and helium R21 values breakdown above thislimit, and the isoscaling phenomenon vanishes. Thissuggests that high pT /A particles come from the nonequilibrated environment.
The antisymmetrized molecular dynamics (AMD)model5,6) is employed with Skyrme SLy4 effective interaction and symmetry energy slope parameter L =46 MeV. The AMD result qualitatively explains isoscaling for pT /A < 280 even though AMD is a dynamical
model. However, AMD underestimate triton R21 and do
not reproduce breakdown of R21 .
References
1) M. B. Tsang et al., Phys. Rev. C 64, 054615 (2001).
2) J. Barney et al., Rev. Sci. Instrum. 92, 063302 (2021).
3) H. Otsu et al., Nucl. Instrum. Methods Phys. Res. B 376,
175 (2016).
4) J. W. Lee et al., Nucl. Instrum. Methods Phys. Res. A
965, 163840 (2020).
5) A. Ono, Prog. Part. Nucl. Phys. 105, 139 (2019).
6) M. Kaneko et al., Phys. Lett. B 822, 136681 (2021).

- S15 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Breakup of proton halo nucleus 8 B at near-barrier energies†
L. Yang,∗1,∗2 C. J. Lin,∗1,∗3 H. Yamaguchi,∗2,∗4 A. M. Moro,∗5,∗6 N. R. Ma,∗1 D. X. Wang,∗1 K. J. Cook,∗7,∗8
M. Mazzocco,∗9,∗10 P. W. Wen,∗1 S. Hayakawa,∗2 J. S. Wang,∗11 Y. Y. Yang,∗12 G. L. Zhang,∗13 Z. Huang,∗13
A. Inoue,∗14 H. M. Jia,∗1 D. Kahl,∗15 A. Kim,∗16 M. S. Kwag,∗17 M. La Commara,∗18 G. M. Gu,∗17
S. Okamoto,∗19 C. Parascandolo,∗20 D. Pierroutsakou,∗20 H. Shimizu,∗2 H. H. Sun,∗1 M. L. Wang,∗13 F. Yang,∗1
and F. P. Zhong∗1,∗3
As recognized since the very ﬁrst measurements inthe mid-1980s,1) the most neutron-rich unstable isotopeof lithium, 11 Li, was reported to present an unexpected
halo-type structure. After this experimental discovery
in 11 Li, several other nuclear systems with neutron halo
structures were reported. On the proton-rich side, 8 B
is one of the few cases whose ground state presents the
proton halo.2) The large extent of the nuclear matter
distribution and the very low threshold of the breakup
channel strongly impact the reaction mechanism, particularly at energies around the Coulomb barrier, where
couplings to the breakup continuums are expected tobe particularly signiﬁcant. Consequently, the detailed
knowledge of the breakup mechanism is critical for anunderstanding of the reaction dynamics of halo nuclear
systems.
The breakup mechanism of the proton halo nuclei israther complicated. The dynamic Coulomb polarization eﬀect3) may produce a hindrance to both the proton transfer and breakup processes,4) which results in
the rather elusive character of proton halo systems. To
obtain a comprehensive understanding of the breakup
process, the coincident measurement of the breakup
fragments is the inevitable course. However, it is asigniﬁcant challenge for incident energies close to the
Coulomb barrier, as it is not easy to carry out a coincidence measurement among the breakup fragments as

was done at higher energies owing to the much reduced
kinematic focusing. It becomes worse owing to the very
low beam intensities of proton halo nuclei.
To address this long-standing challenge, we performed the complete kinematics measurement of
8
B + 120 Sn at two energies around the barrier.5) Owing
to the highly eﬃcient silicon detector array, the correlation of the breakup fragments, 7 Be and proton, isderived for the ﬁrst time. As an example, the relative
energy spectra (Erel ) is presented in Fig. 1. The correlations can be explained by the state-of-the-art continuum discretized coupled channel calculations. The results indicate that 8 B presents distinctive reaction dynamics: the dominance of the elastic breakup. This
breakup occurs primarily through short-lived continuum states and almost exhausts the 7 Be yield. The
correlation reveals that the prompt breakup mechanism
dominates, occurring predominantly on the outgoing
trajectory. We also report that, as a large environment,
the continuum of 8 B breakup may not signiﬁcantly impact elastic scattering and complete fusion.

†

Condensed from the article in Nat. Commun. 13, 7193 (2022)
Department of Nuclear Physics, China Institute of Atomic
Energy∗2 Center for Nuclear Study, University of Tokyo∗3 College of Physics and Technology & Guangxi Key Laboratory of Nuclear Physics and Technology, Guangxi Normal
University∗4 National Astronomical Observatory of Japan∗5 Departamento de FAMN, Universidad de Sevilla∗6 Instituto Interuniversitario Carlos I de Fı́sica Teórica y Computacional (iC1)∗7 Department of Physics, Tokyo Institute of Technology∗8 Facility for Rare Isotope Beams, Michigan State University∗9 Dipartimento di Fisica e Astronomia, Universita di Padova∗10 Istituto Nazionale di Fisica Nucleare-Sezione di Padova∗11 School of Science, Huzhou University∗12 Institute of Modern Physics, Chinese Academy of Sciences∗13 School of Physics, Beihang University∗14 Research Center for Nuclear Physics, Osaka University∗15 Extreme Light Infrastructure—Nuclear Physics, Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH)∗16 Center for Extreme Nuclear Matters, Korea University∗17 Department of Physics, Sungkyunkwan University∗18 Department of Pharmacy, University Federico II∗19 Department of Physics, Kyoto University∗20 Istituto Nazionale di Fisica Nucleare-Sezione di Napoli∗1Fig. 1. Measured Erel distribution (circles) for the breakup
fragment at 38.7 MeV. The vertical line indicates the
expected location of the peak from the ﬁrst 1+ resonanceof 8 B. The solid and dashed curves denote the simulated
distributions of Erel with the orbital angular momentum
up to l = 3 and the l = 1 (1+ ) state, respectively.

References
1) I. Tanihata et al., Phys. Rev. Lett. 55, 2676 (1985).
2) G. A. Korolev et al., Phys. Lett. B 780, 200 (2018).
3) M. Ito et al., Nucl. Phys. A 787, 267 (2007).
4) Y. Kucuk et al., Phys. Rev. C 86, 034601 (2012).
5) L. Yang et al., Nat. Commun. 13, 7193 (2022).

- S16 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Discovery of new isotope 241 U and systematical mass measurement of
neutron-rich Pa-Pu nuclei with KISS-MRTOF system
T. Niwase,∗1 Y. X. Watanabe,∗1 Y. Hirayama,∗1 M. Mukai,∗2 P. Schury,∗1 A. N. Andreyev,∗3 T. Hashimoto,∗4
S. Iimura,∗5 H. Ishiyama,∗2 Y. Ito,∗6 S. C. Jeong,∗1 D. Kaji,∗2 S. Kimura,∗2 H. Miyatake,∗1 K. Morimoto,∗2
J. -Y. Moon,∗4 M. Oyaizu,∗1 M. Rosenbusch,∗1 A. Taniguchi,∗7 and M. Wada∗1

∗4
∗5
∗6
∗7

- S17 -

Atomic number

Projectile nuclide 238U

91 (Pa)90 (Th)Limit of known masses

This work

1∗3

Wako Nuclear Science Center (WNSC), IPNS, KEK
RIKEN Nishina Center
School of Physics, Engineering and Technology, University
of York
Institute for Basic Science
Department of Physics, Rikkyo University
Advanced Science Research Center, Japan Atomic Energy
AgencyInstitute for Integrated Radiation and Nuclear Science, Kyoto University

92 (U)
24∗2

94 (Pu)93 (Np)=∗1

95 (Am)

A

144

146

148

150

152

154

Neutron number

156

Fig. 1. Part of nuclear chart of the neutron-rich actinide
region. Red dashed line indicates the mass known line,
and red hexagon symbols denote the measured data inthis work.

16
12

Resonant laser for 241U

241U2+
241Pu 2+4019540.30

201001 laps(a)8Counts / 3 ns

We previously operated the KEK Isotope Separation
System (KISS)1,2) for nuclear spectroscopy of neutronrich nuclei around N = 126 and beyond. We explore
neutron-rich uranium regions with a recently developed multi-reﬂection time-of-ﬂight mass spectrograph(MRTOF-MS).3) In this manuscript, we report the ﬁrst
systematic mass measurements of neutron-rich Pa-Pu
isotopes produced as projectile-like fragments (PLF)
via several multi-nucleon transfer (MNT) channels of
the 238 U + 198 Pt reaction at the KISS facility.
The experimental setup of KISS facility is described
elsewhere.1,2) A rotating 198 Pt (enriched to 91.63%)
target with a thickness of 12.5 mg/cm2 was bombarded
by a primary beam of 238 U (10.75 MeV/nucleon),
which was provided by the RIKEN Ring Cyclotron
with typical intensity of approximately 30 particle nA.
The isotopes of interest were produced as PLFs in the
MNT reactions, with their masses and velocities being
close to those of the primary beam particle. Moreover,they were scattered around the grazing angle. Theenergy of reaction products were attenuated using a
40-µm Ti energy degrader to maximize the yield stopping in a doughnut-shaped gas cell ﬁlled with 65-kPa
argon gas.
We successfully performed the high-precision direct
mass measurement of 19 neutron-rich Pa-Pu nuclides(Fig. 1) and discovered a new uranium isotope 241 U.4)
Figure 2(a) shows the TOF spectrum at 1001 laps in
the MRTOF with resonant laser wavelength for the
new isotope 241 U. Figure 2(b) shows the TOF spectrum at 600 laps with resonant wavelength for 241 Np.
The comparison of the spectra in Figs. 2(a) and (b)indicates the identiﬁcation of the new isotope 241 U.
This study was demonstrated to explore theneutron-rich actinide region using MNT reaction via
KISS and MRTOF setup. We plan to use further heavier/symmetric projectile and target combinations suchas 238 U+238 U/248 Cm, which is promising for reaching
more exotic nuclei to understand both astrophysically
relevant processes and the evolution of nuclear struc-

19540.40(b)
241Pu 2+5019540.50

19540.60

19540.70

600 laps

241Np2+ Resonant laser for 241Np

1510

241Np2+11715.95

241U2+

11716.00

11716.05

Time-of-ﬂight [μs]11716.10

Fig. 2. TOF spectra with the solid red lines denoting theﬁtting curves. (a) A/q = 120.5 region after 1001 laps in
the MRTOF-MS with resonant wavelength for the newisotope 241 U. (b) A/q = 120.5 region after 600 laps withresonance for 241 Np. The absolute TOF values were
diﬀerent between (a) and (b) owing to the diﬀerence inthe number of laps.

ture at N = 152 and beyond.
References
1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 353, 4 (2015).
2) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 412, 11 (2017).
3) J. Y. Moon et al., RIKEN Accel. Prog. Rep. 52, 138(2018).
4) T. Niwase et al., Phys. Rev. Lett. 130, 132502 (2023).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

α-cluster structure of 12 C from ﬁrst principles†
T. Abe,∗1 T. Otsuka,∗2,∗1,∗3 T. Yoshida,∗4,∗5 Y. Tsunoda,∗4 N. Shimizu,∗4 N. Itagaki,∗6 Y. Utsuno,∗3,∗4
J. P. Vary,∗7 P. Maris,∗7 and H. Ueno∗1
The 12 C nucleus is of particular importance in stellar nucleosynthesis. It is produced by triple-α reactions through the second 0+ state (Hoyle state). However, the properties of the Hoyle state are not fully
understood. The Hoyle state is still being studied
actively from both sides of experiments and theories.
On the theoretical side, ab initio approaches for lowenergy nuclear structure calculations have been advanced rapidly in recent years, owing to recent computational and methodological developments. Here, wereport the low-lying structure of 12 C studied by the
ab initio calculations in the no-core Monte Carlo shellmodel (MCSM).1)
Figure 1 shows the no-core MCSM results comparedto the experiments. The calculations were carried out
in the basis space of Nshell = 7 with the harmonicoscillator energy of h̄ω = 20 MeV. The Daejeon16 N N
interaction2) was adopted. In Fig. 1, the excitationenergies and transition strengths (B(E2), M (E0)) for++
the ground (0+1 ) and two low-lying (21 , 02 ) states are+indicated. For the 21 state, the Q-moment is also depicted in the unit of e fm2 . As seen in Fig. 1, the nocore MCSM calculations (“th” in the ﬁgure) provide
a reasonable agreement with the experimental values(“exp” in the ﬁgure). It is remarkable that the ab initio
calculations for the low-lying states of the twelve-bodysystem can reproduce the experimental data.

Fig. 1. 12 C excitation spectra and the B(E2) (M (E0)) values in the unit of e 2 fm4 (e fm2 ) compared to experiments. For more details, see Ref. 1).
†
∗1
∗2
∗3
∗4
∗5
∗6
∗7

Condensed from the article in Nat. Commun. 13, 2234
(2022)RIKEN Nishina Center
Department of Physics, University of Tokyo
Advanced Science Research Center, Japan Atomic Energy
AgencyCenter for Nuclear Study, University of Tokyo
Research Organization for Information Science and Technology
Yukawa Institute for Theoretical Physics, Kyoto University
Department of Physics and Astronomy, Iowa State University- S18 -The density in the body-ﬁxed frame (intrinsic density) is closely related to the structure of atomic nuclei.
It is, however, still diﬃcult to observe the intrinsic density experimentally. Thus, the theoretical approaches
are indispensable to investigate the intrinsic densityof atomic nuclei. Figure 2 displays the density distri+butions of the ground (0+1 ) and Hoyle (02 ) states in
4comparison with the α-particle ( He) density. For the
ground state, three α-like clusters are closely lying one
another, being closer to the quantum liquid (i.e., normal nuclear matter). The Hoyle state appears rather
clearly separated three α-like clusters compared to theground state. It is noteworthy that ab initio calculations in the twelve-body system exhibit three-α-likecluster structure of 12 C without any a priori assumptions of α particles.

Fig. 2. (a) Color code of density. (b) Density of the groundstate of the α-particle. (c) Density of the ground stateof 12 C. (d) Density of the Hoyle state of 12 C. See thedetails in Ref. 1).

From the T-plot analysis,3) it is found that the
ground state is composed of the quantum liquid (normal nuclear matter) with ∼94% probability and the
α-like clusters with ∼6% probability, while the Hoyle
state comprises the quantum liquid with ∼33% probability and the α-like clusters with ∼61% probability.
Therefore, the structure of 12 C can be viewed as acrossover of the quantum liquid and clustering in termsof the critical phenomena in quantum many-bod systems. Note that this feature obtained by the T-plot
analysis is veriﬁed by the hierarchical cluster analysis
with dendrogram, that is one of the techniques employed in the machine learning.
Now, we can describe the low-lying structure (static
property) of 12 C. From future perspective, we would
like to apply the no-core MCSM wave functions obtained here to the calculations for triple-α reactions(dynamics) so that we can fully understand the process of the 12 C production in stars from ﬁrst principles.
References
1) T. Otsuka et al., Nat. Commun. 13, 2234 (2022).
2) A. M. Shirokov et al., Phys. Lett. B 761, 87 (2016).
3) Y. Tsunoda et al., Phys. Rev. C 89, 031301(R) (2014).

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Isovector density and isospin impurity in 40 Ca†
H. Sagawa,∗1,∗2 S. Yoshida,∗3 T. Naito,∗4,∗1 T. Uesaka,∗5 J. Zenihiro,∗6 J. Tanaka,∗1 and T. Suzuki∗7

ε2 = (0.928 ± 0.586) %.

(1)

This central value is about 50% larger than thevalue of RPA calculations without the ISB forces.
From this value of the isospin impurity, the strengthof CSB interaction s0 is further obtained as s0 =− (8.80 ± 16.0) MeV fm3 .
In summary, we studied the IV density of 40 Ca using
†
∗1
∗2
∗3
∗4
∗5
∗6
∗7

Condensed from the article in Phys. Lett. B 829, 137072(2022)RIKEN Nishina Center
Center for Mathematical Sciences, University of Aizu
Science Research Center, Hosei University
Department of Physics, University of Tokyo
RIKEN Cluster for Pioneering Research
Department of Physics, Kyoto University
Department of Physics, Nihon University

0.3
0.2

4r2IV ( fm-1 )Experimental charge densities have been studied byelectron scattering experiments since the 1950s. Protondensities can be extracted from charge densities removing the proton ﬁnite-size eﬀect. It has been shown in
Ref. 1) that proton elastic scattering is quite useful to
extract the neutron density from the angular distributions of cross sections and analyzing powers of polarized
proton beams.
Charge symmetry breaking (CSB) and charge independence breaking (CIB) forces have been discussed
in the context of isospin impurity eﬀect on the superallowed Fermi decays. The quantitative information of
isospin symmetry breaking (ISB) forces has been recently examined to calculate the binding energies of
isodoublet and isotriplet nuclei and also the excitationenergies of isobaric analogue states (IAS). This study
introduces the Skyrme-type ISB interactions and study
their eﬀect on the IV density in 40 Ca.
The isovector density deﬁned as the diﬀerence between neutron and proton densities as ρIV = ρn − ρpis plotted with a factor of 4πr2 (Fig. 1). The theoretical predictions of the isovector density are qualitatively
diﬀerent from the experimental results: the experimental result of the isovector density exhibits a peak atr ∼ 3.2 fm, whereas the Hatree-Fock (HF) model with
SAMi-J27 interaction predicts a peak at r ∼ 2.5 fm
with positive values (neutron excess) in the interior andnegative values on the surface.
A strong correlation between the maximum of IV
density and isospin impurity was reported in Ref. 2)
with the correlation coeﬃcient r = 0.992. The isospin
impurity can be extracted from the peak height of the
IV density when the proton and neutron densities areavailable experimentally. The experimental peak heightof the IV density is 0.208 ± 0.066 fm−1 in Fig. 1. Then,the isospin impurity is then extracted from the correlation plot as

40

SAMi-J27
PVC(J27)
SAMi-J27mod
Exp.

Ca

0.1
0.0
-0.1
-0.2
-0.3
0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

r ( fm )Fig. 1. IV densities multiplied by a factor of 4πr 2 of 40 Ca
calculated by the HF, modiﬁed HF and PVC models as well as the experimental IV density. The red(blue) solid and dashed curves denote the HF (modiﬁed
HF) and PVC densities with SAMi-J27 (SAMi-J27mod)model, respectively. The occupation probabilities near
the Fermi surface are optimized to ﬁt the IS density inthe case of modiﬁed HF. The experimental data are denoted with a black solid curve considering the experimental uncertainty depicted by the shaded area.

the mean-ﬁeld and particle-vibration coupling (PVC)
models. We adopted the Skyrme SAMi-J model as themean-ﬁeld model. We observed a signiﬁcant diﬀerence
between the experimental and calculated IS densities in
the interior part and also dilute density region of 40 Ca.
This diﬀerence implies the modiﬁcation of density distribution owing to the reduced occupation probabilities
of single-particle states near the Fermi surface, which
may be caused by many-body correlations beyond themean-ﬁeld model.
It was shown in Ref. 2) that the magnitude of the
IV density signiﬁcantly changes owing to the CSB interaction, whereas the CIB interaction exhibits no appreciable eﬀect. It is found that the CSB interaction
exhibits a strong linear correlation with the maximumof IV density and isospin impurity. Thus, the magnitude of IV density helps experimentally to determine
the isospin impurity and the magnitude of CSB interaction. This characteristic of the IV density appears ingeneral in N = Z nuclei, 40 Ca, 80 Zr, and 100 Sn. The
measurements of the IV density is desired to obtain theexperimental information of the isospin impurity andthe CSB interaction.
References
1) H. Sakaguchi et al., Prog. Part. Nucl. Phys. 97, 1 (2017).
2) H. Sagawa et al., Phys. Lett. B 829, 137072 (2022).

- S19 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Large amplitude collective motion in 44 S†
Y. Suzuki,∗1 W. Horiuchi,∗2,∗3,∗4,∗5 and M. Kimura∗5
It is well known that neutron-rich N ≃ 28 nuclei exhibit strong quadrupole collectivity.1,2) Using antisymmetrized molecular dynamics (AMD), we have discovered many interesting features such as triaxial deformation and shape coexistence in 42 Si and neighboring
nuclei.3,4) Herein, we report the large-amplitude collective motion (LACM) in 44 S.
Figure 1 shows the comparison between the energy
curves and collective amplitudes of 40 Mg and 44 S.
40
Mg possesses the prolately-deformed energy minimum and the collective amplitude of the ground stateis localized around it, whereas the 0+
2 state is localized
in the oblately-deformed region. Thus, 40 Mg depicts
the coexistence of the prolate and oblate rigid rotors.
In contrast, 44 S exhibits a signiﬁcantly diﬀerent structure: The energy curve is extremely ﬂat as a function ofγ and the collective amplitudes of the ground, and the0+
2 states demonstrate broad and non-localized distributions, which imply that 44 S possesses no rigid shapedue to the LACM.
Energy (MeV)

02+ amp.

01+ amp.

4

0.5
0

2

40Mg

Energy00

20

(deg)

=0.3501+ amp.

4
2
0

0
=0.3

0+2 amp.
0

0.5

44S

Energy20

(deg)

40

-0.5
-1
60

Fig. 1. Energy curves and collective amplitudes of the 0+
1
and 0+
2 states as functions of the quadrupole deformation parameter γ. The values of quadrupole parameterβ are set to 0.35 and 0.30 for 40 Mg and 44 S, respectively.

A general question is as follows: Based on which
type of physical quantity, can we distinguish rigid-rotor
and LACM? The monopole transition is the solution
to this question. The monopole transition strength(Table 1) is strongly hindered in 40 Mg, whereas it is
†
∗1
∗2
∗3
∗4
∗5

Mg
0.0
0.0

44

S (calc.)
0.04
0.38

44

S (expt.)5)
0.022(2)non-negligible in 44 S.5) This feature can be explainedusing a two-conﬁguration mixing model.6) 40 Mg possesses prolate ground state and oblate 0+
2 state; hence,
the monopole matrix element is given as ⟨obl.|M|pro.⟩,where |pro.⟩ and |obl.⟩ denote the prolate and oblate
conﬁgurations, respectively, and M denotes the transition operator (1p1h operator). This matrix element
vanishes because single-particle conﬁgurations of |pro.⟩and |obl.⟩ diﬀer by 2p2h. This is the reason why thetransition is strongly hindered in 40 Mg.
Owing to LACM, we approximate 44 S as a mixtureof prolate and oblate shapes with equal amplitudes,
√
|0+
(1)
1 ⟩ = (|pro.⟩ + |obl.⟩)/ 2,√+|02 ⟩ = (|pro.⟩ − |obl.⟩)/ 2.
(2)

+
⟨0+
2 |M|01 ⟩ =Collective amp.

140+
B(E0; 0+
1 → 02 )+B(IS0; 01 → 0+
2 )In this case, the transition matrix read

-0.5
60-1

40

6
Energy (MeV)1

Collective amp.

6

Table 1. Electric (E0) and isoscalar (IS0) monopole transition strengths in Weisskopf unit (Wu).

Condensed from the article in Phys. Rev. C 104, 024327(2021) and Prog. Theor. Exp. Phys. 2022, 063D02 (2022)
Research Center for Nuclear Physics, Osaka University
Department of Physics, Osaka Metropolitan University
Nambu Yoichiro Institute of Theoretical and Experimental
Physics (NITEP), Osaka Metropolitan University
Department of Physics, Hokkaido University
RIKEN Nishina Center- S20 -}
1{⟨pro.|M|pro.⟩ − ⟨obl.|M|obl.⟩
2(3)

Thus, the transition matrix is proportional to the difference in the squared-radii of the prolate and oblate
shapes. Consequently, 44 S possesses non-negligible
monopole transition strength. Using the single AMD
wave functions with prolate and oblate deformationand Eq. (3), we obtain B(E0) = 0.05 Wu and B(IS0)= 0.4 Wu, which are close to the results of the fullmodel space calculation listed in Table 1.
Thus, there is an interesting relationship between
the monopole transition and LACM. In 40 Mg, the prolate and oblate rotors coexist, and the monopole transition is hindered as they do not mix with each other.
In 44 S, there is a considerable mixture of prolate andoblate shapes due to LACM. This leads to the nonnegligible monopole transition, which is roughly proportional to the diﬀerence in the squared-radii of thetwo shapes.
References
1) O. Sorlin et al., Prog. Part. Nucl. Phys. 61, 602 (2008).
2) S. Takeuchi et al., Phys. Rev. Lett. 109, 182501 (2012).
3) Y. Suzuki et al., Phys. Rev. C 104, 024327 (2021).
4) Y. Suzuki et al., Prog. Theor. Exp. Phys. 2022, 063D02(2022).
5) S. Grévy et al., Eur. Phys. J. A 25, 111 (2005).
6) S. Shimoura et al., Phys. Lett. B 654, 87 (2007).

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Measurement of ﬂavor asymmetry of light-quark sea in the proton withDrell-Yan dimuon production in p + p and p + d collisions at 120 GeV†
K. Nakano,∗1,∗2 Y. Goto,∗2 Y. Miyachi,∗3 K. Nagai,∗4 S. Sawada,∗2,∗5 and T.-A. Shibata∗2,∗6
for the E906/SeaQuest Collaboration

2

1.5

CT18
NNPDF4.0

1.4
1.3
1.2
σpd / 2σpp

Evidence for a ﬂavor asymmetry between the ū andd¯ quark distributions in the proton has been found indeep-inelastic scattering and Drell-Yan experiments.1,2)
The asymmetry observed in the E866 experiment3) suggested a drop of the d¯(x) /ū (x) ratio in the x > 0.15
region, where x means the fraction of nucleon momentum carried by partons. Here, we report results fromthe SeaQuest experiment, with improved statistical precision, for the ﬂavor asymmetry in the large x region up
to x = 0.45.
The SeaQuest experiment detects µ+ µ− pairs(dimuons) produced in the Drell-Yan process.4) The differential cross section at leading order is given by:

1.1
1
0.9
Mass-Fit method
Systematic uncertainty
Intensity-Extrapolation method
Systematic uncertainty

0.8
0.7
0.6
0.5
0.05

0.1

0.15

0.2

0.25

2

d σ
4πα
(1)
=
dx1 dx2
9x1 x2 s∑][×e2i qiA (x1 ) q̄iB (x2 ) + q̄iA (x1 ) qiB (x2 ) ,

x2

0.3

0.35

0.4

0.45

0.5

Fig. 1. The cross section ratio versus x2 obtained with thetwo extraction methods.

i∈u,d,s,...

The data that SeaQuest recorded between June 2014
and July 2015 were analyzed.
The result of σ pd /2σ pp using the “IntensityExtrapolation” (IE) method was reported in Refs. 5)
and 6). We developed another method of extracting
σ pd /2σ pp , called “Mass-Fit” (MF) method, in order
to conﬁrm that the systematic uncertainty of the IE
method has been properly evaluated. The results of
σ pd /2σ pp using the two methods are shown in Fig. 1.
They are in excellent agreement.
¯
The ratio of d(x)/ū(x)was derived from σ pd /2σ pp
and reported in Refs. 5) and 6). Using d¯(x) /ū (x) as
input, we can determine the diﬀerence, d¯(x) − ū (x).
It provides a direct measure of the contribution from
non-perturbative processes, since perturbative processes
†

∗1
∗2
∗3
∗4
∗5

∗6

Condensed from the article in arXiv:2212.12160 (2022)
Department of Physics, University of Virginia
RIKEN Nishina Center
Faculty of Science, Yamagata University
High Energy Nuclear Physics, Los Alamos National Lab
Wako Nuclear Science Center (WNSC), IPNS, KEK
College of Science and Technology, Nihon University

should cancel out in d¯(x) − ū (x). Figure 2 showsd¯(x) − ū (x) at Q2 = 25.5 GeV2 over the region 0.13 <x < 0.45. For comparison, experimental data and theoretical calculations are overlaid. The SeaQuest data
have better uncertainty than the existing data, and arein good agreement with the two calculations.
0.4
SeaQuest

0.35

Systematic uncertainty

0.3

NuSea/E866 (Q2 = 54 GeV2)

0.25

HERMES (Q2 = 2.3 GeV2)

0.2
d−u

where α is the ﬁne-structure constant, ei is the chargeof a quark with ﬂavor i, and qiA,B (x1,2 ) are the quark
distribution functions in hadrons A and B for quarks
carrying a momentum fraction x1 and x2 , respectively.
SeaQuest utilized the 120-GeV proton beam at Fermilab
for hadron A and liquid hydrogen and deuterium targets
for hadron B. The cross-section ratio of the two targets¯
has a direct sensitivity to d(x)/ū(x)
as
[
]
σ pd
1
d¯(x2 )
1
+
.
(2)
≈
2σ pp
2
ū (x2 )0.15
0.1

Q2 = 25.5 GeV2

0.05
0
−0.05
−0.1
0.1

Alberg, Ehinger and Miller
Basso, Bourrely, Pasechnik, and Soffer

0.15

0.2

0.25

0.3
x

0.35

0.4

0.45

Fig. 2. Result of d¯(x) − ū (x).

References
1) P. Amaudruz et al., Phys. Rev. Lett. 66, 2712 (1991).
2) A. Baldit et al., Phys. Lett. B 332, 244 (1994).
3) R. S. Towell et al., Phys. Rev. D 64, 052002 (2001).
4) S. D. Drell et al., Phys. Rev. Lett. 25, 316 (1970).
5) J. Dove et al., Nature 590, 561 (2021).
6) Y. Goto et al., RIKEN Accel. Prog. Rep. 55, S16 (2022).

- S21 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Energy measurement of beam from SRC for GUINNESS WORLD
RECORDSTM registration
H. Okuno,∗1 N. Fukuda,∗1 H. Haba,∗1 H. Hasebe,∗1 Y. Higurashi,∗1 H. Imao,∗1 H. Otsu,∗1 H. Sakurai,∗1
Y. Shimizu,∗1 T. Sumikama,∗1 D. Suzuki,∗1 H. Suzuki,∗1 H. Takeda,∗1 K. Yoshida,∗1 and M. Yoshimoto∗1
The SRC (Superconducting Ring Cyclotron) was
registered into GUINNESS WORLD RECORDSTM as
the highest beam energy cyclotron on April 11 2022.1)
The energy of the beam from the SRC was measured
mainly using BigRIPS prior to the registration. The
acceleration of 238 U up to 345 MeV/nucleon was chosen to maximize the energy of the extracted beam.
The energy ET of the beam extracted from the SRC
is expressed as√
ET = (M0 c2 )2 + (pc)2 − M0 c2(1)
pc = Q × ecBρ(2)
M ∼ M0 /Mamu(3)
where M0 , M , Mamu , p, c, Q, e, and Bρ express therest ion mass, mass number, uniﬁed atomic mass unit,
momentum, speed of light, charge state, elementarycharge, and magnetic rigidity, respectively. Therefore,
M , Q, and Bρ must be measured or deﬁned. Z is also
required to be deﬁned in the measurement.
Firstly we must show that the accelerated particle is238
U (Z = 92, M = 238). Mass spectra were measured
in the ion source plasma used in the RIBF accelerator
complex. Measurements were taken at 2 kV and 22 kV
extraction voltages. M/Q was calibrated using the two
peaks of m/q = 1 and m/q = 2 at 22 kV. The obtained
data show that the mass of the heaviest element in thesource is approximately 236. The only nuclei that arestable in nature at these mass numbers are 232 Th or
238
U. The color of the sample in the ion source wasdark brown, a typical color of UO2 , while the color ofThO2 is white. From these reasons, it can be deduced
that the Z and M of the accelerated ion beam are 92
and 238, respectively. The accelerated ion, therefore,
is 238 U.
Secondly, the beam energy is roughly measured.
This measurement helps us to deﬁne charge state of theaccelerated beam in the succeeding measurement. A
target of Be is placed at F0 in BigRIPS, and the energyof the particles in full strip (Q = Z = 92) is measured.
Three target thicknesses are prepared: 0.5 mm, 1 mm,
and 2 mm. The obtained data are plotted as shown in
Fig. 1 together with linear regression. When the thickness of the target is zero, the approximation indicatesthe beam’s original energy. Because the energy loss is
not proportional to the thickness of the target, it is alittle oﬀ from the correct answer but is still accurateenough to identify Q in the next process.
Thirdly, magnetic rigidity Bρ of the accelerated∗1

RIKEN Nishina Center- S22 -

Fig. 1. Energy of 238 U92+ versus the target thickness withlinear regression.

beam is measured through the BigRIPS without thetarget. Because the charge is still undetermined, theblue dots in Fig. 2 show that the energy can jumpfrom one value to another under a constant Bρ condition. In contrast, from the results obtained previously,
we know that the energy is approximately around theorange line, so thus we determined Q to be 86. We
deduced the extracted energy of 82400 MeV by combining the measured Bρ value with Q = 86.

Fig. 2. Beam energy converted from the measured Bρ as afunction of assumed Q values of the accelerated ion.

Reference1) https://www.guinnessworldrecords.com/world-records/
675272-highest-beam-energy-cyclotron .

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of new ionization chamber specialized for high Z
beam (II)M. Yoshimoto,∗1 N. Fukuda,∗1 R. Matsumura,∗1 D. Nishimura,∗2 H. Otsu,∗1 Y. Shimizu,∗1 T. Sumikama,∗1
H. Suzuki,∗1 H. Takahashi,∗2 H. Takeda,∗1 J. Tanaka,∗1 and K. Yoshida∗1
Ionization chambers (ICs) are detectors used to determine the energy deposit (∆E) of the ions with suﬃcient accuracy to distinguish the atomic number (Z) inthe BigRIPS separator and ZeroDegree spectrometer.
A new IC has been developed to improve the Z resolution of heavy ions with Z > 80 and the energy of 200–
300 MeV/nucleon,1) for which experimental proposals
are on the rise. The diﬃculty in Z determination is because of the change in the charge state,2) which is more
pronounced for higher Z beams. To overcome this effect, previous studies suggested the replacement of thecommonly used P-10 with a gas with a smaller or larger
Z.1,3)
We conducted machine studies (MS-EXP21-10, -11)
on the gas dependence of the IC at RIKEN RIBF. The
IC setup has been described in a previous study.1) We
used three gas species, P-10 gas (Ar 90% + CH4 10%),methane gas (CH4 100%) with a smaller cross sectionof the charge state changing, and xenon-based gas (Xe
70% + CH4 30%) with a larger cross section of thecharge state changing. The ICs with these gases wereoperated at 620 Torr in the F7 vacuum chamber.
The ∆E in the IC was measured with 238 U90+, 91+
ions at 344 MeV/nucleon. Figure 1 shows the ∆E distributions for the three gas species. The shape for theCH4 gas diﬀered signiﬁcantly between 90+ and 91+.
The lowest energy peak corresponds to 90+ passing
through the IC without charge state changing and thesecond-lowest peak corresponds to 91+.

Fig. 1. Energy deposit (∆E) distributions of the IC inmethane, P-10, and xenon-based gases irradiated with
344 MeV/nucleon 238 U90+ (blue area) and 238 U91+ (redline).

The shape diﬀerence for the P-10 gas was smaller
than that for the CH4 gas. However, the mean ﬁtted
with a normal distribution changed by 0.56% dependingon the charge states. When multiple charge states aretransmitted, the mean shift adversely aﬀects particle
identiﬁcation (PID). The energy resolution of 90+ and∗1∗2

RIKEN Nishina Center
Department of Natural Sciences, Tokyo City University

91+ was 1.1%, which was worse than the 0.7% energy
resolution required to achieve the 3σ separation at Z =92 from Z = 91 isotopes. In contrast to the CH4 and P10 gases, the xenon-based gas yielded almost identicalshapes for 90+ and 91+. The diﬀerence between themeans was only 0.03%. This is because a charge-state
equilibrium was reached immediately after the injection
into the IC. The energy resolution was obtained to be
0.69%, which is suﬃcient for the 3σ separation in Z.
Hence, the xenon-based gas was demonstrated to besuitable for the IC specialized for high Z beams.
We injected the high-Z secondary beam at approximately A/Q = 2.5 into the xenon-based gas IC. The secondary beam was produced from the 345 MeV/nucleon
238
U primary beam impinging on a 4 mm-thick Be target. The magnetic rigidity of the ﬁrst dipole was 6.3 Tm
and no degraders were used in the separator. The
PID was performed using the TOF-Bρ-∆E method, as
shown in Fig. 2. Further, the beam energy at F7 was
typically 264 MeV/nucleon at Z = 80 −92. Although
the blobs for He-like and H-like ions are dense, the different ion species were well separated and identiﬁed.
The averaged Z resolution of Z = 81−91 was 0.34 (1σ).
The resolution is approximately twice better than thatby the P-10 gas IC.4)

Fig. 2. PID plot of Z versus A/Q obtained with the xenonbased gas IC. The typical energy is 264 MeV/nucleon.

In conclusion, the xenon-based gas IC achieved the 3σ
separation in Z, and rendered the PID for the secondary
beams with Z > 80 at approximately 260 MeV/nucleon
practical for all experimental groups.
References
1) M. Yoshimoto et al., RIKEN Accel. Prog. Rep. 55, 70(2022).
2) H. Weick et al., Phys. Rev. Lett. 85, 2725 (2000).
3) T. Sumikama et al., in this report.
4) N. Fukuda et al., RIKEN Accel. Prog. Rep. 54, 81(2021).

- S23 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Atomic-number identiﬁcation of heavy RI beams using the energy
loss in a Xe-based gas
T. Sumikama,∗1 N. Fukuda,∗1 and M. Yoshimoto∗1

P10 gas (1.00 atm)
Z-Q = 1 -> 2
Z-Q = 2 -> 1
Xe (90%) + CH4 (10%) gas (0.39 atm)
60
Z-Q = 1 -> 2
Z-Q = 2 -> 1

L (cm)

80

Effective length of ionization chamber

20
150

200

250

300

350

Energy (MeV/u)

Fig. 1. Partial mean free path length of the change in the
charge state in the ionization chamber as a function of
the energy of the 208 Rn beam.
∗1

RIKEN Nishina Center

Counts

4000
3000

Rn-208 (Z=86)
At-206 (Z=85)(a)
P10 gasAr (90%) + CH4 (10%)
1 atm

300 MeV/u

2000
1000
1100

6000

1150

1200

1250

1300

1350

Rn-208 (Z=86)(b)
Xe (90%) + CH4 (10%) gas
0.39 atm

At-206 (Z=85)

300 MeV/u

4000
2000
0

1100

1150

1200

1250

Energy deposit (MeV)

1300

1350

Fig. 2. Monte Carlo simulation of the energy deposit in theionization chamber. Half of the energy-loss straggling in
ATIMA was applied for the energy deposit.5)

An experimental study of PID using a Xe-based gas
was already conducted, and a good Z resolution was
obtained.6,7)
References40

0of a Xe-based mixed gas (Xe 90% + CH4 10%). The gaspressure was determined so that the energy deposit at
300 MeV/nucleon is same as that of the P10 gas. Evenat 300 MeV/nucleon, L is shorter than that of P10 at
185 MeV/nucleon, indicating a better Z resolution.
The energy loss in the ionization chamber was simulated by using the energy-loss code ATIMA4) andGLOBAL. The ﬂuctuation in Q was taken into account by the Monte Carlo method. The Z resolution of
the 180-MeV/nucleon 210
85 At beam was simulated to be
0.46%, which is consistent with the experimental valueof 0.45%. Figure 2 shows the energy deposit of the 300MeV/nucleon 208 Rn and 206 Ac beams into the eﬀective
region of the ionization chamber. The Z resolution is
improved from 0.60% for the P10 gas to 0.39% for the
Xe-based gas. This result is consistent with the discussion of Fig. 1.

CountsRadioactive isotope (RI) beams produced at RIBF
are tagged event-by-event with the atomic number Z
and mass-to-charge ratio A/Q determined using beamline detectors. For heavy RI beams, particle identiﬁcation (PID) becomes diﬃcult owing to the change in Q
inside the beam-line detectors because Z is determinedfrom the energy loss depending on Q2 . Blobs in the PID
plot were clearly visible for the 208 Rn case1) but not forthe 220 Th case.2) The relative Z resolutions were 0.45%
and 0.69% (1σ) for the 185-MeV/nucleon 208 Rn beamand 315-MeV/nucleon 220 Th beam, respectively. The
worse resolution was considered to be due to the energyloss straggling caused by charge-state ﬂuctuation in thegas of the ionization chamber. The diﬀerence between
these two cases indicates the impact of the energy dependence of the charge-state ﬂuctuation.
In this paper, the diﬀerence in the Z resolutions is
discussed in regards to the energy dependence of thecross section of the change in Q in the gas using the
GLOBAL code.3) Figure 1 shows the energy dependence of the partial mean free path length L, givena change in Z − Q from 1 to 2 or from 2 to 1. Theenergy dependence of L is mainly for the electronpickup reaction. In the 208 Rn case, the mean valueof the equilibrium charge-state distribution ⟨Q⟩ is 84.5
at 185 MeV/nucleon. Since ⟨Q⟩ is a decimal, thecharge state must change multiple times in the ionization chamber to make the eﬀective Q in a single
event closer to 84.5. L (Z−Q = 1→2) is roughly 1/2 ofthe eﬀective length of the ionization chamber, as indicated by the dotted line in Fig. 1. Thus, even if Z − Qchanges from 2 to 1, it could be back. In contrast, L(Z−Q = 1→2) is longer than the eﬀective length at
315 MeV/nucleon. Z − Q might not change to 2 once it
becomes 1. This is mainly the nature of Ar gas, which
accounts for 90% of the P10 gas. Figure 1 also shows L

1) T. Sumikama et al., Nucl. Instrum. Methods Phys. Res.
B 463, 237 (2020).
2) N. Fukuda et al., RIKEN Accel. Prog. Rep. 54, 81(2021).
3) C. Scheidenberger et al., Nucl. Instrum. Methods Phys.
Res. B 142, 441 (1998).
4) https://web-docs.gsi.de/~weick/atima/ .
5) Y. Sato et al., RIKEN Accel. Prog. Rep. 46, 159 (2013).
6) M. Yoshimoto et al., 19th Int. Conf. on Electromagnetic
Isotope Separators and Related Topics (EMIS XIX),
Daejeon, South Korea, Oct. 3–7, 2022.
7) M. Yoshimoto et al., in this report.

- S24 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Improved transmission of OEDO
T. Chillery,∗1 S. Michimasa,∗1 N. Imai,∗1 D. Suzuki,∗2 M. Dozono,∗2,∗3 N. Fukuda,∗2 T. Haginouchi,∗2,∗4
S. Hanai,∗1 S. Hayakawa,∗1 Y. Hijikata,∗2,∗3 J. W. Hwang,∗5 S. Ishio,∗2,∗4 N. Iwasa,∗2,∗4 K. Kawata,∗1
R. Kojima,∗1 K. Kusaka,∗2 J. Li,∗1 M. Ohtake,∗2 K. Okawa,∗1 T. Saito,∗5 Y. Shimizu,∗2 T. Sumikama,∗2
H. Suzuki,∗2 H. Takeda,∗2 H. Tanaka,∗2,∗6 T. Teranishi,∗2,∗6 Y. Togano,∗2 Y. Yanagisawa,∗2 R. Yokoyama,∗1
K. Yoshida,∗2 and M. Yoshitomo∗2

∗1
∗2
∗3
∗4
∗5
∗6
a)

Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center
Department of Physics, Kyoto University
Department of Physics, Tohoku University
CENS, Institute for Basic Science
Department of Physics, Kyushu University
S0 focal plane = target position in the TINA silicon-detector
array, as used in the 130 Sn experiment.

Fig. 1. COSY-calculated beam trajectories in the X andY planes between F3 and S1 for low energy tuning in
OEDO.

F3 – S0: ~ 85%

S0 Y [mm]The optimized energy degrading optics (OEDO) system1) was installed at RIBF in 2017. The principle
aim of OEDO is to decelerate and focus medium-heavy
radioactive ion beams provided by BigRIPS from approximately 200 to 15–50 MeV/nucleon. The system
was commissioned in the day 0 campaign by studying
transfer reactions on 77 Se, 93 Zr, and 107 Pd. During
this, the transmission from F3 decreased from 61% at
FE9 to 18% at S0, despite the eﬀective focusing effort of the RF-Deﬂector (RFD) at FE10. This poortransmission was attributed to the small bore radiusof the quadrupole magnet, i.e. QE19, located at FE11,
and thus, during 2021, the OEDO beamline was reconﬁgured. The QE20 (STQ18) magnet was installed
upstream of FE11 (FE12), and the QE19 magnet was
entirely removed from the beamline. The impact to
OEDO’s low-energy focusing capabilities was tested
in April 2022 during the machine study “MS22-1”
followed by the SHARAQ18 experiment2) measuring130
Sn(d, p)131 Sn. This report summarises the new lowenergy optics of the OEDO beamline, including the improved transmission.
The ion-optical transport code COSY-Inﬁnity (v 9.0)
was used to simulate the beam transport through theupdated F3–S1 beamline. The beam trajectories in X
and Y planes are shown in Fig. 1. Compared with theprevious beam trajectories,1) the new magnet setup between the RFD and S0a) should enable higher transmission to the secondary target. In addition, the QE20
magnet placed downstream of the RFD enables the ﬁnetuning of the parallel beam condition, which was notpossible in the previous conﬁguration.
COSY matrix elements for the new OEDO transport
were incorporated into the CNS-developed Monte Carlosimulation code. The simulation used the measured
condition at F3 from MS22-1 and included beamline
materials, the opening of the beam pipes, and the RFD.
The simulated spot size at S0 was X(Y ) = ±5 (10) mm,within the target radius of 25 mm. The estimated F3–
S0 transmission was 97% till third-order aberrations.
Following optics tuning in April 2022, the measured
130
Sn beam spot at S0 is shown in Fig. 2. The beam was

S0 X [mm]130Fig. 2.
Sn Beam focus at S0. Red circle represents theCD2 target’s radius of 25 mm.

centred at X(Y ) = −2(−1) mm with a spot size of ±8(12) mm, within the CD2 target’s radius of 25 mm. The
beam energy was degraded to 23.3 ± 1.1 MeV/nucleon
at S0. The measured F3–S0 transmission of 85% islower than the calculated value of 97%; however, it still
improves OEDO’s transmission by a factor of 4.7 overthe previous condition.1) Following this improved transmission of low-energy beam, we performed the OEDO
experiment2) to measure 130 Sn(d, p)131 Sn.
References
1) S. Michimasa et al., Prog. Theor. Exp. Phys. 2019
043D01 (2019).
2) N. Imai et al., in this report.

- S25 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Operation test of kicker system with new PFN capacitors
Y. Yamaguchi,∗1 T. Ohnishi,∗1 G. Hudson-Chang,∗1,∗2 M. Kanda,∗3 Y. Koizumi,∗3 D. Nagae,∗1,∗4 K. Okubo,∗3
K. Sasaki,∗3 N. Shinozaki,∗3 A. Yano,∗5 A. Ozawa,∗1,∗5 T. Yamaguchi,∗1,∗3,∗5 and M. Wakasugi∗1,∗6
In the rare-RI ring (R3) facility, the kicker system
is a key device for injecting and extracting particles
one-by-one. Recently, we have succeeded in magnetic
ﬁeld ﬂattening during injection duration and extending the extraction duration, thereby improving the experimental eﬃciency.1) However, the ceramic capacitors used in the pulse forming network (PFN) of the
kicker power supply were broken several times due toinsulation breakdown after 1 day of operation with acharging voltage of 45 kV to 55 kV in the 2021 massmeasurement experiments.2,3) This failure, which interferes with the execution of the experiment, must be
repaired quickly. We report the progress of the repair
work.
The PFN, consisting of sixteen capacitor and inductor sections, forms a high-voltage unit together witha thyratron and other components.4) The high-voltage
unit is installed in a tank ﬁlled with insulating oil.
The capacitor HP40-H132-00 we have used so far ismade by the former AVX corporation (Kyocera AVX
now). It has a three-layer structure and is insulatedwith molded resin. The outer diameter is 38 mm, thelength is 47 mm, the rated voltage is 80 kV, and thecapacitance is 375 pF.
A failure analysis was performed by Kyocera. The
central part of the three-layer structure was found tobe particularly damaged (see Fig. 1(b)). The damage was so severe that it is diﬃcult to pinpoint thecause, but the following are possible causes: 1) due
to the part of dielectric layer is slightly weak, 2) due
to the stacked element structure, the central element
overheated, and then the increase in dielectric loss andfurther overheating caused an electron avalanche, orFig. 1. (a) shows broken AVX capacitor, and (b) showsinternal damage revealed by Kyocera.
∗1
∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Department of Physics, University of Surrey
Department of Physics, Saitama University
Laboratory for Zero-Carbon Energy, Tokyo Institute ofTechnology
Institute of Physics, University of Tsukuba
Institute for Chemical Research, Kyoto University- S26 -

3) due to electric ﬁeld concentration on the washer
between the elements. Thus, it is thought that thestacked elements structure could not withstand our useof the repetition of the high-voltage charging within
200 µs and the instantaneous discharging by thyratron. Then we decided to replace it with a single-layer
structure capacitor, a commercially available productwith proven track record.
Figure 2(a) shows a new capacitor FHV-10AN madeby TDK corporation. The outer diameter is 38 mm,
the length is 33 mm, the rated voltage is 50 kV, andthe capacitance is 700 pF. Two TDK capacitors areconnected in series to make almost the same capacitance as the AVX one. Figure 2(b) indicates the output currents when operated at a charging voltage of
55 kV. It can be seen that the waveform (blue-line)
obtained with TDK capacitors is almost the same asthat (black-line) obtained with AVX capacitors.

Fig. 2. (a) shows installed new capacitors. (b) indicates
output signals from current monitor (details in text).

There are eight high-voltage units in total. Currently, the two high-voltage units for one twin-type
kicker magnet have been replaced with TDK capacitors. Recently, we conducted 5-days continuous operation test for all units with a charging voltage ofaround 50 kV. As a result, ﬁve of the six units with
AVX capacitors failed again. On the other hand, thetwo units with TDK capacitors had no problems. We
concluded that the use of TDK capacitors would solve
the above three concerns and enable stable continuous
operation. Therefore, the remaining six high-voltage
units will also be replaced with new capacitors soon.
References
1) Y. Yamaguchi et al., RIKEN Accel. Prog. Rep. 54, 100(2021).
2) A. Ozawa et al., RIKEN Accel. Prog. Rep. 55, 13(2022).
3) S. Naimi et al., RIKEN Accel. Prog. Rep. 55, 14 (2022).
4) Y. Yamaguchi et al., Phys. Scr. T166, 014056 (2015).

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Design of radiation shield for RI production beam line
A. Akashio,∗1 K. Tanaka,∗1 N. Shigyo,∗1,∗2 K. Sugihara,∗1,∗2,∗3 and H. Haba∗1
A radiation shield for a target of new radioactive isotope (RI) production beamline at the large irradiation
room in the Linac building was designed. Figure 1 shows
the schematic of the shield. A 7.18 MeV/nucleon helium4 beam is irradiated from upward to downward on a
bismuth target. In this study, the conceptual structureof the radiation shield for the side direction from thetarget was designed using the radiation transport code
PHITS.1) The size of the shield was limited to less than
2 m because the new RI production beam line will be installed at the small space in the large irradiation room.
In addition, the requested shield weight was less than 10
ton owing to the load capacity of the ﬂoor. Although
the PHITS calculation is not well studied in this helium4 beam energy region, the benchmark has already beenobtained via measurement of the neutron yield with thesame beam condition.2)

the heavy material such as lead set outside PE as shownin Fig. 1.
Figure 2 shows position distribution of the neutronand γ-ray radiation dose rate calculated by PHITS. Although the tungsten-inner shield was also assumed, iron
was selected considering the cost and weight. The ironthickness was optimized to realize the minimum thickness of the shield satisfying the requested neutron dose
rate at the shield surface. Despite the 30-cm-thick ironand 50-cm-thick PE successfully reducing the neutron
dose rate, the γ-ray dose was still serious. The main
component was a 2.2 MeV secondary γ ray attributed
to the reactions between neutrons and proton includedin the outer PE shield as shown at black-dashed line in
Fig. 2. Therefore, additional heavy weight lead shieldoutside PE is necessary to reduce the γ ray. To render
the lead thickness thinner, reduction of low-energy neutron entering to outer PE shield was considered. PE with
10% B2 O3 (BPE) was installed between the iron and the
PE to apply 10 B(n, α) reaction. Red lines in Fig. 2 show
the eﬀect of 10 cm BPE. The generated γ ray is reduced
down to 1/8 by BPE shield at the border between innerand outer shield. Although the 50 cm thick BPE wasalso evaluated as an alternative to the PE, 10 cm BPE
was suﬃcient because low energy neutron from iron-innershield was absorbed by the ﬁrst 10 cm of BPE. Owing
to the boron eﬀect, the thickness of the lead was successfully reduced approximately 5 cm. Owing to the design, the shield of iron 30 cm thick, BPE of 10 cm, PEof 40 cm, and lead of 7 cm satisﬁed the requirement of
10 µSv/h on the surface against 100 particle µA helium-4
beam.

Fig. 1. Schematic of the radiation shield.

The radiation dose around the target is 3 × 108 µSv/h
at the beam intensity of 100 particle µA. This study
aimed to reduce the neutron and γ-ray dose rate below
10 µSv/h on the surface of the shield. A simple shieldcomposed of one substance is not eﬀective when neutrons and γ rays in wide range energies are mixed. The
maximum energy of neutrons from the target is about
approximately 15 MeV. In general, polyethylene (PE) or
water, a hydrogen-rich material, is eﬀective in shielding
neutrons up to several MeV. For the higher energy neutron, iron or other heavy metal material is applied as
an inner shield to reduce the neutron energy by inelastic scattering. Subsequently PE is applied as an outershield to reduce the neutron dose rate. In addition, thesecondary γ ray generated in the shield is absorbed in
∗1
∗2
∗3

RIKEN Nishina Center
Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University
High Energy Accelerator Research Organization (KEK)

Fig. 2. Radiation dose distribution calculated with PHITS.
The assumed helium-4 beam intensity was 100 particle µA.

References
1) T. Sato et al., J. Nucl. Sci. Tech. 55, 684 (2018).
2) K. Sugihara et al., Nucl. Instrum. Methods Phys. Res. B
470, 15 (2020).

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Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Amorphous to polycrystalline phase transition in La2 O3 ﬁlms grown
on a silicon substrate forming Si-doped La2 O3 ﬁlms†
S. R. Lee,∗1 A. Kim,∗2,∗3 S. Choi,∗2,∗3 T. Ikeda,∗4 T. Kobayashi,∗5 T. Isoshima,∗6 S. Cho,∗7 and Y. Kim∗1,∗8
Currently, the semiconducting industry is heavily reliant on Si-based electronic devices. SiO2 has beenused as a principal dielectric in Si-based industry owing
to its good ﬁlm properties and stability in the complementary metal-oxide-semiconductor (CMOS) process.
However, its low dielectric constant has raised issuesof low performance of device and large leakage current with decreasing gate thickness, channel length,etc. Consequently, extensive eﬀorts have been made toﬁnd alternative dielectrics with high-permittivity (κ)
on Si as a replacement for SiO2 . One of importantconditions for high-κ dielectric is that the dielectric
layer should not result in the formation of silicide or
SiO2 interfacial layer between silicon wafer and dielectric layer. Intriguingly, it has been shown that upon
the deposition of La2 O3 is deposited on Si, La silicate
is formed rather than a SiO2 interfacial layer.1)
In this study, we used a pulsed laser deposition(PLD) method to obtain a high-quality La2 O3 ﬁlm ona Si substrate. Using a high-resolution transmission
electron microscope (HRTEM) it was observed thatapproximately 10 nm thick amorphous La2 O3 layer
was initially formed on Si. Subsequently, and thena polycrystalline La2 O3 layer was formed on top of
the amorphous La2 O3 layer, as Fig. 1(a), which is attributed to Ostwald’s step rule, this is a metastablestate formation prior to the formation of a stable stateof a material. HRTEM images also suggested thatno interfacial oxide layer was formed between La2 O3and Si. Furthermore, through an in-depth study using Rutherford backscattering (RBS), performed at the
RIKEN Pelletron accelerator facility, it was further
conﬁrmed that La-Silicate interfacial layer is extremely
reduced, as Fig. 1(b). Rather, the results of X-ray photoelectron spectroscopy atomic depth proﬁle analysis,using Ar+ ion beam sputtering, indicated the presenceof La-silicate present over the entire La2 O3 ﬁlm, as
Fig. 1(c). This suggests that Si diﬀuses through whole
thick La2 O3 ﬁlms, thereby forming Si-doped La2 O3
ﬁlms. Our study suggests that employment of ad†
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8

Condensed from the article in Phys. Status Solidi A 219,
2200318 (2022)
Surface and Interface Science Laboratory, RIKENInterdisciplinery Materials Measurement Institute, Korea
Research Institute of Standards and Science
Department of Nano Science, University of Science andTechnology
RIKEN Nishina Center
Neutron Beam Technology Team, RIKEN
RIKEN Cluster for Pioneering Research
Division of Physical Metrology, Korea Research Institute ofStandards and Science
Department of Applied Chemistry, University of Tokyo- S28 -

Fig. 1. (a) Transmission electron microscope image ofpolycrystalline/amorphous La2 O3 ﬁlms, (b) Rutherford backscattering, and (c) X-ray photoelectron spectroscopy atomic depth proﬁle of La2 O3 /Si.

vanced growth technique may improve the status of
high-κ gate oxide of La2 O3 gate oxide in CMOS industry.
Reference
1) T. Kawanago et al., Proc. 41st European Solid State
Device Research Conf., Helsinki, Finland, 2011-4, p. 67.

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Proton hyperpolarization relay from nanocrystals to liquid water†
N. Matsumoto,∗1 K. Nishimura,∗1 N. Kimizuka,∗1 Y. Nishiyama,∗2 K. Tateishi,∗3,∗4 T. Uesaka,∗3,∗4 andN. Yanai∗1,∗4,∗5
While nuclear magnetic resonance (NMR) spectroscopy is indispensable over a wide range of ﬁelds fromchemistry to medicine, it suﬀers from inherently poorsensitivity due to low nuclear spin polarization. Dynamic
nuclear polarization (DNP), in which the electron spinpolarization is transferred to the nuclear spins, is one of
the most promising methods to improve the sensitivity of
NMR. Water is an extremely attractive and ubiquitoustarget material because hyperpolarized water can leadto highly sensitive NMR of proteins and biomolecules.1)
Here, we report the nuclear spin hyperpolarization of
bulk liquid water achieved via a novel strategy called“hyperpolarization relay,” in which the photogenerated
transient electron spin polarization is transferred to the
nuclear spins within nanocrystals, and then transferredto the nuclear spins of liquid water (Fig. 1).

Fig. 2. (a) Chemical structures of DAT (5,12-diazatetracene)
and p-terphenyl. (b) 1 H NMR spectra of the mixture of
NC170 and water at thermal equilibrium (black) and after
triplet-DNP for 120 s (green). (c) Enlarged 1 H NMR spectra before (black) and after triplet-DNP for 120 s (green)
after subtracting the ﬁtted spectra of NC170 .

enhancement factor of nanocrystals and water was estimated as 104 ± 10 and 2.4 ± 0.3 times, respectively. The
transfer of proton spin polarization from the nanocrystal
surface to water was indicated by the size dependence ofthe nanocrystals. As the nanocrystal size increased from
170 nm to 270 nm and 390 nm, the enhancement of water polarization decreased from 2.4 ± 0.3 to 1.5 ± 0.2 andFig. 1. Schematic of “hyperpolarization relay” from nanocrys- 1.2±0.1 times. This trend supports that the polarization
tals to bulk liquid water.
transfer occurs at the interface between the nanocrystals
and water.
To better understand the nanocrystal-to-water polarWe prepared organic nanocrystals of 5,12-diazatetracene(DAT)-doped p-terphenyl (Fig. 2(a))2) using the repre- ization transfer mechanism, the polarization buildup was
cipitation method,3) that can be hyperpolarized at room simulated using Solomon equations. Interestingly, a negtemperature by DNP based on photoexcited triplet state ative cross relaxation rate constant was obtained, which(triplet-DNP).4) The size of nanocrystals was character- often occurs in macromolecules or viscous liquids. This
ized by dynamic light scattering (DLS) measurements. implies that the water dynamics are slowed at the surface
Nanocrystals of three sizes were fabricated and referred of nanocrystals. A possible scenario is that polarization
to as NC390 , NC270 , and NC170 , respectively. The num- is transferred from the nanocrystals to the surface-bound
ber represents the average diameter of the nanocrystal. water and that the surface-bound water exchanges with
The nanocrystals were mixed with water of 10% H2 O in the bulk water, resulting in the enhanced polarization of
D2 O with a weight ratio of NC: water = 1 : 4 for the the bulk water.
In conclusion, we demonstrated the polarization retriplet-DNP experiments.
In the 1 H NMR spectrum for the mixture of NC170 lay that ﬁrst transfers the polarization from photoexand water at thermal equilibrium, only a sharp peak cited triplet electron spins to proton spins within thefrom water was observed (Figs. 2(b) and 2(c)). After nanocrystals, and then transfers the polarization to proa triplet-DNP sequence for 120 s, the intensity of the ton spins of water on the nanocrystal surface. This will
water-derived sharp peak clearly increased in addition lead to the realization of a continuous hyperpolarized
to the enhanced nanocrystal-derived broad peak. The water supply system that will revolutionize life scienceand drug discovery.
†

∗1
∗2
∗3
∗4
∗5

Condensed from the article in J. Am. Chem. Soc. 144, 18023(2022)
Department of Applied Chemistry, Kyushu University
RIKEN-JEOL Collaboration Center, RIKEN
RIKEN Nishina Center
Spin-Isospin Laboratory, CPR, RIKENPRESTO and FOREST, JST

References
1) T. Harris et al., J. Phys. Chem. B 118, 3281 (2014).
2) H. Kouno et al., J. Phys. Chem. Lett. 10, 2208 (2019).
3) H. R. Chung et al., J. Cryst. Growth 294, 459 (2006).
4) K. Nishimura et al., Chem. Commun. 56, 7217 (2020).

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Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Estimation of the on-site Coulomb potential in La2 CuO4 : A µSR and
DFT Study
M. R. Ramadhan∗1,∗2 and I. Watanabe∗1,∗2
Since its discovery in the late 1980s, hightemperature superconducting cuprates are known tohave a rich variety of physics and have attracted interest from researchers worldwide. There are open questions on exotic electronic states that need to be investigated, such as pseudogaps, stripes of spins and holes,
and charge-ordered states. These properties are usuallydescribed on the basis of the strong on-site Coulomb potential, U, and the covalent states of the Cu 3d orbitals
with the surrounding O 2p orbitals. To understandmore about these properties, La2 CuO4 (LCO) can beused as the ideal candidate material. LCO is the parent
compound of high-Tc superconducting is classiﬁed as a
Mott insulator, and has strong covalent states between
the Cu 3d and O 2p orbitals. These interactions produce antiferromagnetic insulating behavior due to theexistence of the on-site Coulomb potential energy (U).
The value of U of this system has been thoroughly investigated but still has large ambiguities in the range of
3–10 eV, raising uncertainties in the discussion of theelectronic states in high-Tc superconducting cuprates.
Our group has been developing a technique to estimate the value of U by combining the muon spin rotation (µSR) and density functional theory (DFT) andincluding U as an adjustable parameter (DFT + U).
From an experimental perspective, a muon is a sensitive local magnetic probe that can be used to observe
the ordered state of LCO. Our group has shown that an
implanted muon has three frequency components using
the high-statistic µSR ,as shown in Fig. 1. These threefrequency components can be translated into three internal ﬁelds of 426.7(1), 109.2(4), and 1251.6(3) G.1)
From a theoretical perspective, we develop a method
to obtain a more precise muon position by utilizing
DFT + U. From calculations, we show that there arethree possible positions at which a muon can reside.
As discussed in the previous APR report, we expand
the calculation further by considering the local eﬀect
of an implanted muon from both the crystal and spin
structures of supercell LCO.2,3) After that, we also consider the zero-point vibration motion (ZPVM) of an
implanted muon inside the structure by calculating the
distribution of the muon position as a quantum particle.4) Both of these considerations can be utilized to
calculate the internal ﬁeld by using the following equation:[]∑(⃗ri −⃗rj )12
ρi (⃗ri −⃗rj )ρ |ψj | . (1)
3 3⃗
2 −⃗
|⃗
r
−⃗
r
|
|⃗
r
−⃗
r
|
i
j
i
j
i,j
Here, ρ⃗i denotes the vector data for the spin grids and∗1∗2

Department of Physics, Universitas Indonesia
RIKEN Nishina Center

Fig. 1. Fourier transfrom spectrum from the high-statisticµSR experiment.

⃗ri − ⃗rj denotes the relative distance between Cu-spin
grids with a density of ρ⃗i and the muon distribution
grids ψj . Then, we sum all grid components obtained
from our DFT calculations to estimate the internal ﬁeld
at each muon, a sphere with a radius of 50 Å. Afterobtaining the internal ﬁelds for each ﬁelds muon position, we optimize U by comparing the calculated internal ﬁelds with the experimental internal ﬁelds:
(
)
Mi
Mi
∆HMi = HDF(2)
T − HµSR , |i = 1, 2, 3|,
and sum all ∆HMi for each U with the ﬁtting errors of
the internal ﬁelds, σi , as follows:
2
∑ ∆HM
i

σi2

i

,

|i = 1, 2, 3|.

(3)

By applying the Gaussian function, we obtain optimized U of 4.87(4) eV. By using this optimized U, we
observe that the diﬀerence between the calculated andexperimental internal ﬁelds for the M1, M2, and M3
positions are 3.4 (≈1%) , 38.2 (≈40%), and 97.9 (≈8%)
G respectively.1)
References
1) M. R. Ramadhan et al., Phys. Rev. Res. 4, 033044(2022).
2) M. R. Ramadhan et al., RIKEN Accel. Prog. Rep. 51,
197 (2017).
3) M. R. Ramadhan et al., RIKEN Accel. Prog. Rep. 52,
173 (2018).
4) M. R. Ramadhan et al., RIKEN Accel. Prog. Rep. 53,
150 (2019).

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Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Comparison of basis sets for DFT calculation of guanine nucleobase
W. N. Zaharim,∗1,∗2 S. Sulaiman,∗1,∗2 H. Rozak,∗1,∗3 and I. Watanabe∗1,∗2
Deoxyribonucleic acid (DNA) consists of two
polynucleotide chains twisted around each other in theform of a double helix. DNA is formed using sequencesof four nitrogenous bases (guanine, adenine, cytosine
and thymine). Several reports showed that µSR is anexperimental technique that can be used to study theproperties of organic systems.1–3) The interpretation
and analysis of the µSR results are often complemented
and enhanced through computational studies.4–7)
Two possible muon stopping sites have been reported for each nitrogenous base.4) In guanine nucleobase, muon is likely to attach itself to the carbon
atom (C8). The DFT cluster framework using hybrid functional was used in this study.8–11) In thisstudy, B3LYP were used in combination with 6 different standard set of Gaussian basis function; (1) 631+G, (2) 6-31+G(d), (3) 6-31+G(d,p), (4) 6-31++G,(5) 6-31++G(d), (6) 6-31++G(d,p). The question of
how the functional and the basis set is chosen will affect the optimized geometry and electronic structure
calculated is therefore becoming the motivation of thisstudy.
Figure 1 shows the total energy of the optimized
structure calculated using diﬀerent basis sets. 6-31+G
and 6-31++G produce an optimized structure with thehighest energy compared to the other basis sets. The
diﬀerence in energies between the basis set that uses
a diﬀuse function to all atoms and diﬀuse function to
all atoms except hydrogen is only 0.01 eV. A huge difference in total energy is observed when polarization
function is used in the basis set. Total energy produces
by using a basis set that includes polarization function

is reduced by approximately ∼5 eV. Polarization function gives more room for the atom to get away fromeach other to minimize the electron-electron repulsion
thus reduces the total energy of the system.
The estimated isotropic interaction values calculatedusing diﬀerent basis sets were summarized in Fig. 2.
6-31++G basis set produces the lowest isotropic interaction value. This is due to the diﬀuse functionused in the atomic orbital calculation for all atoms including muon. The diﬀuse function allows the electron
to move far away from the nucleus which may aﬀect
the isotropic interaction value. As the electron moves
far away from the nucleus the isotropic interaction decreases. In particular, among all basis sets, high hyperﬁne frequency was produced when using 6-31+G(d, p).
This value is 13.18% lower than the experimental value
obtained by Hubbard et al.4) and it is the closest to theexperimental value.

Fig. 2. Isotropic interaction values obtained using diﬀerent
basis sets.

Fig. 1. The total energy of the optimized structure using
diﬀerent basis sets.
∗1
∗2
∗3

RIKEN Nishina Center
Computational Physics Laboratory, School of Distance Education, Universiti Sains Malaysia
Graduate School of Engineering and Science, Shibaura Institute of Technology- S31 -The DFT cluster method was applied to study theeﬀects of diﬀerent basis sets on the electronic structure and properties of guanine nucleobase. The basis
set with polarization function should be utilized for
applications where the total energy is crucial and thediﬀuse function can be excluded to all atoms in a calculation that considers the isotropic interaction between
the muon and atoms at the trapping location. By considering both total energy and muon hyperﬁne interaction, 6-31+G(d, p) basis set is the best one to use for
guanine nucleobase molecules.
References
1) K. Nagamine et al., J. Condens. Matter Phys. 16, S4797(2004).
2) K. Nagamine et al., Physica B 404, 953 (2009).
3) E. Torikai et al., Physica B 374, 441 (2006).

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)

4) P. L. Hubbard et al., J. Phys. Chem. 108, 9302 (2004).
5) P. L. Hubbard et al., Physica B 374, 437 (2006).
6) R. Scheicher et al., HFI/NQI 2004, (Springer, 2005),
p. 53.
7) R. Scheicher et al., Physica B 374, 448 (2006).
8) W. N. Zaharim et al., J. Phys. Soc. Jpn. 90, 044301(2021).
9) W. N. Zaharim et al., Acta. Chem. Scand. Omega 6, 40(2021).
10) W. N. Zaharim et al., J. Phys. Soc. Jpn. 91, 094301(2022).
11) A. Jamaludin et al., J. Phys. Soc. Jpn. 91, 024301(2022).

2- S32 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Relative formation probabilities
for ﬂuoride and oxyﬂuoride anions of U, Np, Pu and Am inaccelerator mass spectrometry measurements at VERA†
A. Wiederin,∗1,∗2 M. Kern,∗1,∗2 K. Hain,∗1 M. Martschini,∗1 A. Sakaguchi,∗3,∗4 P. Steier,∗1 A. Yokoyama,∗3,∗5
and R. Golser∗1
Atomic anions of actinides are not formed eﬃciently
in a Cs sputter ion source, so they must be extracted
as molecular anions for AMS measurements.1) Fluoride
anions were introduced as an alternative to the oxideanions previously established for this purpose.2) Somepotential beneﬁts of ﬂuoride extraction of actinides
have already been reported: Fluorine is monoisotopic,
ﬂuoride anions have the potential for increased ionization yields in low cesium ﬂux ion sources,2) could reduce
the hydride background2) and show some degree of elemental selectivity.3) Furthermore, ﬂuoride and oxyﬂuoride molecular anions could also be of use in isobar
separation techniques such as Ion Laser InterAction
Mass Spectrometry (ILIAMS)4) or the Isobar Separator
for Anions (ISA).5) The eﬃciency with which an anion
species is formed in the sputter process is determined by
the electron aﬃnity of the corresponding neutral atom
or molecule.1) The stability of an anion against photodetachment in systems like ILIAMS is in turn also
related to this electron aﬃnity.
Developing such isobar separation methods in theactinide range could open up new possibilities for the
study of actinides in the environment, such as new potential isotopic spikes for normalization or an extended
multi-actinide analysis with simpliﬁed chemistry froma single AMS sample.
Based on estimates of the releases from nuclear tests
and reprocessing plants, 237 Np is thought to be thesecond most abundant anthropogenic actinide in theenvironment.6) 237 Np exhibits conservative behavior innatural waters as it mainly exists in the highly soluble
7)
Np(V)O+and has a
2 form under oxidizing conditions
6
long half-life (T1/2 = 2.1 × 10 y). These two properties
could turn 237 Np into a valuable tool for tracking environmental processes such as water mass transport.8,9)
The main obstacle to establishing 237 Np as an environmental tracer is the lack of an isotopic spike material
for a matrix independent and reliable normalization of237
Np measurements by mass spectrometric methods.
For this purpose, 236 Np was produced via the232
Th(7 Li, 3n)236 Np reaction at the RIKEN Nishina
Center. In addition to the desired 236g Np, isobaric contamination can arise either from 236 U produced by neu†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 528, 40 (2022)
Faculty of Physics, Isotope Physics, University of Vienna
Vienna Doctoral School of Physics, University of Vienna
RIKEN Nishina Center
Faculty of Pure and Applied Sciences, University of Tsukuba
Institute of Science and Engineering, Kanazawa University

tron capture on 235 U impurities in the irradiation target, or from the decay of metastable 236m Np to 236 U or
236
Pu, so further analysis of the mass 236 fraction was
required.
The relative formation probabilities of AnF−
5,
−
−
−
,
AnF
,
AnF
O
and
AnF
O
AnF4 O− , AnF3 O−
3
2 2,
2
4
with An representing the actinides U, Np, Pu or Am,−
have been investigated. The AnF−
4 /AnF5 ratios ofthese actinides have been shown to be element-speciﬁc
within each measurement, with an order of magni−
tude separating the AnF−
4 /AnF5 ratios from one actinide element to the next. The magnitude factor isrobust and reproducible. Based on these ﬁndings, the−AnF−
4 /AnF5 ratio serves as an elemental ﬁngerprint. A
signiﬁcant amount of isobaric interference would shift
this ratio relative to the reference ratio for the actinide
of interest as determined on calibration samples in thesame measurement. The prospective neptunium spikematerial provided a ﬁrst application for this kind of
isobar analysis, and the tentative ﬁrst results are compatible with a successful production and chemical separation of 236 Np.
Choosing the tetraﬂuoride system molecular anions
for the extraction of Np and U suppresses the interfering isobar 236 UF−
4 by an order of magnitude compared
to 236 NpF−
intheion source. The large number of4(oxy) ﬂuoride anions of various actinides greatly enhances the possibility of ﬁnding suitable molecular ion
systems for isobar separation using methods such as
element-selective photodetachment in ILIAMS.
References
1) R. Middleton, Nucl. Instrum. Methods Phys. Res. 122,
35 (1974).
2) X. L. Zhao et al., Nucl. Instrum. Methods Phys. Res. B
510, 10 (2022).
3) X. L. Zhao et al., Nucl. Instrum. Methods Phys. Res. B
294, 356 (2013).
4) M. Martschini et al., Nucl. Instrum. Methods Phys. Res.
B 456, 213 (2019).
5) J. Eliades et al., Nucl. Instrum. Methods Phys. Res. B
268, 839 (2010).
6) J. M. Kelley et al., Sci. Total Environ. 237-238, 483(1999).
7) W. L. Keeney-Kennicutt et al., Mar. Chem. 15, 133(1984).
8) P. Lindahl et al., J. Environ. Radioact. 82, 285 (2005).
9) M. Lopez-Lora et al., Sci. Total Environ. 708, 135222(2020).

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Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Extraction of 229 Th3+,2+ using RF carpet gas cell and observation ofinternal conversion process of 229m Th
Y. Shigekawa,∗1 A. Yamaguchi,∗2,∗3 K. Tokoi,∗4 N. Sato,∗1 M. Wada,∗5 and H. Haba∗1
The ﬁrst excited state of the 229 Th nucleus, 229m Th,
has an excitation energy of ∼8.3 eV,1,2) which maylead to variations in the decay modes (internal conversion (IC), electronic bridge (EB) transitions, and γray emission) depending on the chemical environment.
To observe the EB transitions and γ-ray emission of
229m
Th, we are aiming to trap 229m Th ions such as229m
Th3+ , 229m Th2+ , 229m Th+ , and 229m Th molecularions in an ion trap.3) We previously developed a radiofrequency (RF) carpet gas cell and extracted 220 Rn
ions emitted from an 224 Ra source.3) In this study, wefabricated an ion trap and then extracted and trapped229
Th ions produced from a 233 U source. Moreover,
we conﬁrmed the existence of the IC decay of 229m Th
using 229 Th ion bunches created by the ion trap, which
was reported only by the Munich group.4,5)
We fabricated a quadrupole ion trap having threesegments (Trap 1, 2, and 3), and it was connected
between the quadrupole ion guide (QPIG) and thequadrupole mass separator (QMS), as shown in Fig. 1.
Gasses can be introduced into the ion-trap region forchanging the chemical state of 229m Th ions. Trap 1 has
four T-shaped electrodes called LINAC rods,6) whichmake axial gradient to rapidly move ions downstream
in the presence of gas.

Fig. 1. Schematic view of the ion trap connected with the
RF-carpet gas cell and the QMS.

We placed a 233 U source (diameter 90 mm,
596(10) kBq) inside the RF-carpet gas cell. The gas
cell was ﬁrst evacuated to less than 1 × 10−7 Pa by agetter pump, and then ﬁlled with puriﬁed He gas of
10 mbar. 229 Th ions recoiling out of the 233 U source
were decelerated by the gas and transported by DC
and RF voltages to the ion trap. First, we continuously extracted ions by operating the ion trap as anion guide and detected them with a multichannel plate
detector (MCP). As shown in Fig. 2, we successfully
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Quantum Metrology Laboratory, RIKENPRESTO, Japan Science and Technology Agency
Graduate School of Science, Osaka University
Wako Nuclear Science Center, IPNS, KEK- S34 -

Fig. 2. Mass spectrum of ions extracted to the MCP.

extracted 229 Th3+ and 229 Th2+ using the RF-carpet
gas cell, having simpler electronics and a smaller chamber size than the RF-funnel gas cell developed by the
Munich group.4)
We made short ion bunches using the ion trap for
observing the IC electrons of 229m Th. First, the ionswere trapped in Trap 3 by applying +10 V to Lens 2(Fig. 1) at a He pressure of 0.5 Pa. They were collisionally cooled for 20 ms and then extracted downstream by switching the voltage of Lens 2 to −35 V.
Each ion bunch had ∼270 229g, m Th3+ (∼5 229m Th3+ ),and ∼80 233 U3+ ions. The ion bunches were repeatedly extracted to the MCP by two diﬀerent MCP surface voltages of −2000 and −50 V to detect only ionsand both ions and IC electrons, respectively. Figure 3 shows the time traces of the MCP counts. For
229
Th3+ , the decay curve for −50 V is clearly diﬀerent from that for −2000 V, while no such diﬀerence
is observed for 233 U3+ . The shapes of ion bunches at

Fig. 3. MCP counts as a function of the time at MCP surface voltages of −50 V (red) and −2000 V (blue) for229
Th3+ (left) and 233 U3+ (right). The plots are arranged so that the peak tops at 134 µs are matched toeach other.

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)−2000 and −50 V should be the same as observed for
233 3+
U . Hence, the decay curve having longer lifetimefor 229 Th3+ at −50 V corresponds to IC electrons of
229m
Th, which were emitted after the neutralizationof 229m Th3+ on the MCP surface.4) The preliminary
value of the IC-decay half-life is 8(1) µs, which is consistent with the previous study (7(1) µs5) ). Hence, we
successfully conﬁrmed the existence of the IC decayof 229m Th.4,5) We will introduce some reactive gasses
into the ion trap to make various chemical species of229m
Th to observe the EB transitions.
References
1) B. Seiferle et al., Nature 573, 243 (2019).
2) A. Yamaguchi et al., Phys. Rev. Lett. 123, 222501(2019).
3) Y. Shigekawa et al., RIKEN Accel. Prog. Rep. 55, 127(2022).
4) L. von der Wense et al., Nature 533, 47 (2016).
5) B. Seiferle et al., Phys. Rev. Lett. 118, 042501 (2017).
6) A. Loboda et al., Eur. J. Mass Spectrom. 6, 531 (2000).

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Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Innovative targeted alpha therapy for prostate cancer: preclinicalevaluation of [211 At]PSMA5†
T. Watabe,∗1,∗2 K. Kaneda-Nakashima,∗2,∗3 Y. Shirakami,∗2 Y. Kadonaga,∗1,∗2 K. Ooe,∗2 Y. Wang,∗4 H. Haba,∗4
A. Toyoshima,∗2 J. Cardinale,∗5 F. Giesel,∗5 N. Tomiyama,∗2 and K. Fukase∗2,∗3
Prostate cancer is currently the most prevalent cancer among men (92,021 new cases/year in Japan). After surgery and radiation therapy, hormone therapy is
performed for recurrent lesions. However, the prognosis
is poor if the hormone therapy becomes resistant withmultiple metastases.
In recent years, prostate-speciﬁc membrane antigen (PSMA), which is a membrane marker expressedin prostate cancer, has received signiﬁcant attention.
PSMA is expressed in more than 90% of prostatecancers.1) Targeted α-therapy (TAT) for PSMA is apromising treatment for metastatic castration-resistant
prostate cancer (CRPC).2) Astatine is an α-emitter(half-life T 1/2 = 7.2 h) that can be produced by a
30 MeV cyclotron. In this study, we evaluated the treatment eﬀect of 211 At-labeled PSMA compounds in mouse
xenograft models.
211
At was procured from RIKEN via the short-lived
RI supply platform. Upon procurement, dry distillation
was used to separate and purify 211 At. 211 At-labeled
PSMA1, PSMA5, and PSMA6 were synthesized by thesubstitution reaction of 211 At with the dihydroxyboryl
groups.3)
Tumor xenograft models were established by subcutaneous transplantation of human prostate cancer
cells (LNCaP) in NOD/SCID mice.4) [211 At]PSMA1,[211 At]PSMA5, or [211 At]PSMA6 was administered to
LNCaP xenograft mice to evaluate biodistribution at
3 and 24 h. The treatment eﬀect was evaluatedby administering [211 At]PSMA1 (0.40 ± 0.07 MBq),[211 At]PSMA5 (0.39 ± 0.03 MBq), or saline. Histopathological evaluation was performed for the at-risk organs
at three and six weeks after administration.
All the animal experiments were performed in compliance with the guidelines of the Institute of Experimental
Animal Sciences. The protocol was approved by the Animal Care and Use Committee of the Osaka University
Graduate School of Medicine.
[211 At]PSMA5 resulted in higher tumor retention
compared to [211 At]PSMA1 and [211 At]PSMA6 (30.6 ±
17.8, 12.4±4.8, and 19.1±4.5%ID/g at 3 h versus 40.7±
2.6, 8.7±3.5, and 18.1±2.2%ID/g at 24 h, respectively),
whereas kidney excretion was superior in [211 At]PSMA1
compared to [211 At]PSMA5 and [211 At]PSMA6. The
administration of [211 At]PSMA5 had an excellent treat†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Eur. J. Nucl. Med. Mol. Imaging. 50, 849 (2023)
Graduate School of Medicine, Osaka University
Institute for Radiation Sciences, Osaka University
Graduate School of Science, Osaka University
RIKEN Nishina Center
University Hospital Dusseldorf

Fig. 1. (a) Planar images of [211 At]PSMA5 in LNCaP
xenograft mice.
High uptake was observed in the
xenografts (arrows). (b) Change in the tumor size after administering [211 At]PSMA1 (0.4 MBq, n = 5),[211 At]PSMA5 (0.4 MBq, n = 12), or control (saline,n = 10).

ment eﬀect on tumor growth. [211 At]PSMA1 also
showed a substantial treatment eﬀect; however, the tumor size was relatively more prominent than in the caseof [211 At]PSMA5. In the histopathological evaluation,
regenerated tubules were detected in the kidneys at threeand six weeks after administering [211 At]PSMA5. No
abnormality was found in the histology of the thyroid.
TAT using [211 At]PSMA5 resulted in excellent tumor growth suppression with minimal side eﬀects inthe normal organs. [211 At]PSMA5 should be considered as a new possible TAT for metastatic CRPC. An
investigator-initiated clinical trial will start at the Osaka
University after tox studies.
References
1) T. Watabe et al., Ann. Nucl. Med. 35, 523 (2021).
2) C. Kratochwil et al., J. Nucl. Med. 57, 1941 (2016).
3) Y. Shirakami et al., Sci. Rep. 11, 12982 (2021).
4) F. Soeda et al., J. Nucl. Med. 60, 1594 (2019).

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Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Prevention of radionuclide-induced antibody denaturation maintains
active targeting and maximizes antitumor eﬃcacy in
211
At-radioimmunotherapy†
H. Takashima,∗1,∗2 K. Ohnuki,∗3 S. Manabe,∗2,∗4,∗5,∗6 Y. Koga,∗1,∗7 R. Tsumura,∗1 T. Anzai,∗1 Y. Wang,∗2
X. Yin,∗2 N. Sato,∗2 Y. Shigekawa,∗2 A. Nambu,∗2 S. Usuda,∗2 H. Haba,∗2 H. Fujii,∗3 and M. Yasunaga∗1
Selective tumor accumulation of alpha emitters withhigh linear energy transfer and a short particle range
in tissue results in potent antitumor eﬃcacy without
serious toxicity. Thus, there is a growing interest in
developing novel target alpha therapies. Astatine-211(211 At) is a promising alpha emitter that is applicableto cancer treatment.
In the preparation process of radioactive antibodies, caution should be exercised in the radionuclideinduced chemical reaction causing antibody denaturation.
We demonstrated that reactive oxygen
species (ROS) generated from 211 At-induced radiolysis of water denature astatinated antibodies.1) The
radionuclide-induced antibody denaturation disrupts
binding activity and attenuates in vivo antitumor effect. In contrast, sodium ascorbate (SA), a free radical scavenger, successfully quenches ROS and prevents
denaturation, resulting in the maintenance of binding activity and antitumor eﬀect.2) Although we revealed the inﬂuence of radiochemical reaction on 211 Atlabeled antibody as described above, several questions
remain. First, it is unclear whether 211 At-induced denaturation aﬀects the pharmacokinetics of radioactive
antibodies, such as half-life in blood circulation, distribution to normal organs, and tumor accumulation via
active targeting and passive targeting, which are basedon antigen-antibody reaction and enhanced permeability and retention eﬀect, respectively.3) In addition, theprotective eﬀects of SA on the pharmacokinetics havenot been clariﬁed.
In this study, using an 211 At-labeled anti-human epidermal growth factor receptor 2 (HER2) antibody stabilized with SA, a denatured radioactive anti-HER2
antibody, and an 211 At-labeled nontargeted control antibody (anti-CD20 antibody) stabilized with SA, we
compared their residence time in blood circulation, dis†

∗1

∗2
∗3
∗4

∗5
∗6
∗7

Condensed from the article in Mol. Pharm. 20, 1156 (2023)
Developmental Therapeutics, Exploratory Oncology Research & Clinical Trial Center (EPOC), National Cancer
Center
RIKEN Nishina Center
Division of Functional Imaging, EPOC, National Cancer
CenterLaboratory of Functional Molecule Chemistry, Pharmaceutical Department and Institute of Medicinal Chemistry,
Hoshi University
Research Center for Pharmaceutical Development, Tohoku
University
Glycometabolic Biochemistry Laboratory, RIKEN
Department of Strategic Programs, EPOC, National Cancer
Center- S37 -

Disrupted active targeting
Low tumor accumulation
Less antitumor effectRadiolysis

Disrupted binding activity

Sodium ascorbate

Maintained binding activity

Maintained active targeting
High tumor accumulation
Greater antitumor effectFig. 1. Graphical abstract of this study.

tribution to normal organs, tumor accumulation, andantitumor eﬀect in a xenograft model with high expression of HER2.
In sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, we conﬁrmed that 211 At denatured radioactive anti-HER2 and anti-CD20 antibodies under no protection, and SA successfully stabilized the radioactive antibodies. The binding activity of the denatured radioactive anti-HER2 antibody
was consistently disrupted, whereas the binding activity of the stabilized immunoconjugate was comparable
to the naked antibody. Similarly, the cytocidal eﬀectof the denatured radioactive anti-HER2 antibody on
HER2-positive cancer cells was attenuated more than
the stabilized radioactive antibody.
There is no diﬀerence in blood circulation time aswell as distribution to normal organs between thegroups administered 211 At-labeled anti-HER2 antibody under SA protection and the denatured radioactive anti-HER2 antibody in ex vivo biodistribution
study. These ﬁndings suggest that 211 At-induced antibody denaturation may not aﬀect tumor accumulation via passive targeting. However, single-photon
emission computed tomography and ex vivo biodistribution studies demonstrated that tumor accumulation of 211 At-labeled anti-HER2 antibody stabilizedwith SA was signiﬁcantly higher than that of the denatured radioactive anti-HER2 antibody and 211 Atlabeled nontargeted control antibody under SA protection. In a xenograft model with high expression of
HER2, the stabilized radioactive anti-HER2 antibody
consistently outperformed the denature immunoconjugate and the radioactive nontargeted control antibody. 211 At-induced antibody denaturation hampers

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)

tumor accumulation via active targeting, attenuating
antitumor eﬃcacy, whereas SA successfully maintains
tumor targeting and antitumor activity. In alpharadioimmunotherapy, active targeting signiﬁcantly increases tumor accumulation of 211 At.
In conclusion, SA-dependent protection that maintains tumor targeting and in vivo antitumor effect will facilitate the clinical application of 211 Atradioimmunotherapy.
References
1) S. Manabe et al., ACS Omega 6, 14887 (2021).
2) H. Takashima et al., Cancer Sci. 112, 1975 (2021).
3) Y. Matsumura et al., Cancer Res. 46, 6387 (1986).

2- S38 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Identiﬁcation of a sex determining gene in a dioecious plant Silene
latifolia †Y. Kazama,∗1,∗2 M. Kitoh,∗1 T. Kobayashi,∗1 K. Ishii,∗2,∗3 M. Krasovec,∗4,∗5 Y. Yasui,∗6 T. Abe,∗2 S. Kawano,∗7
and D. A. Filatov∗4
Silene latifolia is a dioecious ﬂowering plant with
XY-type sex chromosomes belonging to the Caryophyllaceae family. Since its discovery in 1923 as one of theﬁrst species with sex chromosomes discovered in higher
plants, it has been used for studies of sex chromosome
evolution and sex-determining mechanisms in plants.1,2)
Two sex-determining genes have been postulated to bepresent on the Y chromosome: the male-promoting gene(SPF) and the female-suppressor gene (GSF). However,the Y chromosome is 1arge (approx. 660 Mb) and mostof it comprises a non-recombining region and occupied
by repetitive sequences, which has prevented genome sequence assembly and rendered the identiﬁcation of sexdetermining genes diﬃcult.
We irradiated S. latifolia with heavy-ion beams to obtain several hermaphroditic (GSF-deﬁcient) and asexual (SPF-deﬁcient) mutants, and mapped the shareddeleted regions of mutants as two sex-determining regions, respectively.3) Genome sequencing and RNA-seq
were performed on two of the hermaphroditic mutants
with small deletion sizes. Sequences were then compared
between male, female, and mutants. Consequently, we
found three genes that were present and expressed only
in males. One gene was commonly deleted in both of
the 11 hermaphroditic mutants and females, which was
identiﬁed as a candidate gene for GSF. Further, a Blast
search revealed that this gene was highly homologous to
the Arabidopsis CLV3 gene, which regulates the size ofthe shoot apical meristems (SAMs) and ﬂower bud primordia.4)
clv3 mutants exhibited increased carpel size, whiletransgenic plants with overexpression of CLV3 showed
suppressed carpel development, suggesting that this geneis a promising candidate for the GSF. Furthermore, in
addition to the Y copy (GSFY ), we found its X-lined
gametolog (GSFX ). RT-PCR results showed that both
GSFY and GSFX were expressed in the shoot apicalmeristems and young ﬂower buds. The translation product of CLV3 is known to act as a peptide with 12 aminoacid residues in the ﬁnal product. Therefore, we compared the amino acid residue sequences of GSFY and
GSFX peptides and found that the sixth glycine residuein GSFX was mutated to an alanine residue. As this
†
∗1
∗2
∗3
∗4
∗5
∗6
∗7

Condensed from the article in Mol. Biol. Evol. 39, msac195(2022)
Department of Bioscience and Biotechnology, Fukui Prefectural University
RIKEN Nishina Center
National Institutes for Quantum Science and Technology(NIRS)
Department of Biology, Oxford University
CNRS, Sorbonne University
Graduate School of Agriculture, Kyoto University
Graduate School of Frontier Sciences, University of Tokyo

mutation is the same as that of the Arabidopsis clv31/clv3-5 mutant (CLV3m), GSFX was considered to bea loss-of-function type. When these peptides were artiﬁcially synthesized and treated to the SAMs of S. latifolia.
GSFY was found to be active in suppressing SAM size,
similar to CLV3, where GSFX and CLV3m were inactive. Next, when GSFY was introduced into Arabidopsis
thaliana, a hermaphroditic plant, the carpel development
was inhibited. However, introduction of GSFX did notinhibit development of the carpel. Furthermore, treatment of ﬂower buds of S. latifolia with the GSFY peptide
also inhibited the development of the pistils. These results indicate that GSFY, a homolog of the CLV3 gene,is a likely candidate of the sex-determining gene thatsuppresses gynoecium development in S. latifolia, andthat GSFX on the X chromosome is dysfunctional.
We have previously shown that, in contrast to GSFY,SlWUS1, which is considered to function in enlarging thecarpels, is present on the X chromosome but not on the
Y chromosome in S. latifolia.5) This suggests that thefunction of the X chromosome functions is to promote
female development. In fact, there is a report in theold literature that the creation of XXXXY pentaploid
chromosomes cause the carpels to enlarge and produce
hermaphroditic ﬂowers.6) The manner in which the Y
chromosome acquired the dominant GSFY during theevolution of sex chromosomes has been the greatest mystery; however, this system, wherein the X chromosome
enlarges the carpels and the Y chromosome reduces its
size, can successfully explain the emergence of the dominant GSFY (Fig. 1).

Fig. 1. Model for the evolution of S. latifolia sex chromosomes with GSFX dysfunction and loss of SlWUS1 in
the Y chromosome.

References
1) E. Kejnovsky et al., Cytogenet. Genome Res. 129, 250(2010).
2) D. Charlesworth, Genetics 210, 1143 (2018).
3) Y. Kazama et al., Sci. Rep. 6, 18917 (2016).
4) J. C. Fletcher et al., Science 283, 1911 (1999).
5) Y. Kazama et al., G3 (Bethesda) 2, 1269 (2012).
6) H. E. Warmke, Am. J. Bot. 33, 648 (1946).

- S39 -

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Screening for high-growth mutants in sporophytes of Undaria
pinnatiﬁda using heavy-ion beam irradiation†
Y. Sato,∗1,∗2 T. Hirano,∗1,∗3 Y. Hayashi,∗1 N. Fukunishi,∗1 S. Kawano,∗4 and T. Abe∗1
Undaria pinnatiﬁda (Wakame) is primarily cultivated as a food resource on Japan’s Sanriku coast,
but production yield is declining due to environmental changes and a decrease in the number of producers. To meet domestic market demand, excellent strainsthat improve productivity per producer must be developed. Until now, there have been no results of mutation breeding using heavy ion beams in brown macroalgae. Our previous study developed a technique for producing mutants in the gametophyte from zoospores obtained by irradiance of heavy-ion beams on the sporophylls.1) However, this method limits the time for obtaining mature sporophylls. Therefore, in this study,
gametophytes and young sporophytes of this alga were
irradiated with a heavy-ion beam, and the subsequentculture was conducted using a tank system (CFCS)2)
to select elite cultivars without aquaculture on the sea.
The mother plant for the irradiation was collected from Hirota Bay, Iwate Prefecture. According to the method described in previous studies,1,2)
the zoospores were induced and cultured to gametophytes and sporophytes. Gametophytes, and sporophytes were irradiated with C ions (135 MeV/nucleon,
LET, 30.0 keV/µm) at a dose of 0.5–25 Gy or Ar
ions (95 MeV/nucleon LET, 284 keV/µm) at a doseof 0.2–10 Gy. The sporophytes obtained from theseions irradiated gametophytes, and the irradiated sporophytes were cultivated in a 7 L plastic tank for about
two weeks and then transferred to a CFCS for cultivation. UV-sterilized seawater was used throughout thecultivation. The seawater temperature and light intensity were set at 10◦ C and 100 µmol photons m−2 s−1 ,respectively. On the 100th day after the start of cultivation, mutant candidates (M1 ) were selected basedon a total length of 100 cm or more and an individual weight of 40 g or more. Cultivation was continued
until sporophylls were formed and zoospores could becollected. The sporophytes obtained by crossing maleand female gametophytes derived from the individual
zoospore were cultured for 20 days, and the total length
was measured. Subsequently, the culture of M2 wascontinued, and those with a weight twice that of the
non-irradiated group, at 100 days after germination,
were selected as excellent mutant candidates (M2 ). M2
was then cultured until sporophylls were formed, released zoospores, and obtained gametophytes.
The survival rate of irradiated individuals varied de†

∗1
∗2
∗3
∗4

Condensed from the article in Cytologia 86, 291 (2021)
RIKEN Nishina Center
Riken Food Co., Ltd.
Faculty of Agriculture, University Miyazaki
Future Center, Tokyo University

pending on the irradiated generation, ions, and dose.
The decreasing rate was more pronounced in the sporophyte than in the gametophyte at higher doses. Although the survival rates of female gametophytes irradiated with heavy-ion beams with C and Ar ionsdecreased with increasing dose, those of male gametophytes did not decrease after both irradiations. These
diﬀerences in sensitivity to ions may be inﬂuenced by
diﬀerences in haploid and diploid stages or diﬀerencesin tissue structure.
In the M1 generation, 18 individuals were selectedfrom 210 sporophytes obtained from irradiated gametophytes, and 30 were selected from 297 irradiated sporophytes. As a result of cultivating the sporophyte obtained by self-crossing of these 48 individuals and conﬁrming their growth, a total of four lines was obtainedfor particularly large individuals compared to others; 3lines [1302G-R68 (C ions, 5 Gy), 1302G-B60 (Ar ions,
0.2 Gy), 1302G-W40 (Ar ions, 2.5 Gy)] from M1 candidate of irradiated gametophytes, and one line [1302SR40 (C ions, 2 Gy)] from the M1 candidate of the irradiated sporophyte (Fig. 1). Among these four lines,
the weight of the largest individuals on the 100th dayof cultivation was two to three times that of the nonirradiated group, so they were selected as M2 individuals. In addition, a sensory test was conducted after
cutting oﬀ a part of the blade and boiling it; the taste
and texture of M2 candidates did not diﬀer from thoseof the non-irradiated individuals. As a result of cultivating the next-generation sporophytes from the gametophytes obtained from M2 , all four lines showed earlier
growth in size than non-irradiated individuals, similar
to the M2 generation. These lines are stored as M3 , conﬁrming the ﬁxation of the mutation. In the future, thesehigh-growth mutants can be used for food production
and biomass utilization, including feed and fertilizer.

Fig. 1. Sporophytes in selected M2 lines (3 lines out of total
4 lines) containing high-growth mutants 100 days after
germination. (a): 1302G-B60 line, (b): 1302G-W40 line,(c) 1302S-R40 line. Bars = 10 cm.

References
1) T. Hirano et al., Phycological Res. 68, 63 (2020).
2) Y. Sato et al., J. Appl. Phycol. 29, 1683 (2017).

- S40 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Radio-ﬂuorogenic nanoclay gel dosimeters with reduced linear energy
transfer dependence for carbon-ion beam radiotherapy†
T. Maeyama,∗1,∗2 A. Mochizuki,∗1 K. Yoshida,∗1 N. Fukunishi,∗2 K. L. Ishikawa,∗3 and S. Fukuda∗4
The complex therapeutic dose distributions associated with new heavy-ion irradiation techniques require the development of 3D dosimeters; however, theprecise measurement of dose distributions when using
high linear energy transfer (LET) radiation remainsa challenge. Speciﬁcally, the dosimeter sensitivity is
typically decreased, and signal saturation occurs as
a result of recombination reactions induced by highdensity ionization and excitation. Thus, heavy-ion
beam dosimetry necessitates a sensitivity correction
for the LET being used. Consequently, we reported
a magnetic resonance imaging-based 3D chemical gel
ion-beam dosimeter for high LET irradiation that does
not require the correction.1) However, several hundred
Gy is required to perform measurements.
For improving the sensitivity, we examined the development of a new gel dosimeter based on ﬂuorometry, which is the most sensitive detection method forradiation-induced products. Gel dosimeters compriseof a radiation-sensitive compound, a gelling agent, andwater. In the case of low LET radiation, several typesof radio-ﬂuorogenic gel dosimeters have been reported
to date, and we have prepared highly sensitive nanoclay radio-ﬂuorogenic gel (NC-RFG)2,3) dosimetersfrom dihydrorhodamine 123 (DHR123) and nano-sized
clay. The non-ﬂuorescent DHR123 was oxidized to
ﬂuorescent rhodamine 123 (RD123) via exposure toionizing radiation. The spatial information that describes the absorbed dose distribution was retained in
the nanoclay gel matrix. Consequently, scanning spatial dosimetry can be performed using a ﬂuorescent gel
such as this because the ﬂuorescence intensity increases
linearly with increasing absorbed dose.
In the NC-RFG using DHR123, the dose-responseor sensitivity of this gel dosimeters decreases with increasing LET, because RD123 is produced by oxidation reactions, primarily with OH radicals. Therefore, this study developed a method for reducing theeﬀect of LET on NC-RFG dosimeters. Through theuse of a new and optimal Fe3+ catalyst together withpyridine (Py) as a dispersant, more than 20 samples of NC-RFG with diﬀerent preparation conditions
were investigated. They were irradiated with 135
and 290 MeV/nucleon 12 C6+ ions accelerated by the
RIKEN Ring Cyclotron and the Heavy Ion Medical
†

∗1
∗2
∗3
∗4

Condensed from the article in Med. Phys. 50, 1073 (2023)
Department of Chemistry, Kitasato University
RIKEN Nishina Center
Department of Nuclear Engineering and Management, University of Tokyo
QST Hospital, National Institutes for Quantum Science andTechnology- S41 -

Accelerator in Chiba, respectively. In this paper, only
the preparation conditions after optimization are presented.
The prepared NC-RFG was deaerated with 1 mM
Fe3+ , 100 mM Py, 100 µM DHR123, and 2 wt% Clay.
The dose response of ﬂuorescence intensity (IFL ) of irradiated samples was obtained via a ﬂuorescence gel
scanner. Figure 1(a) shows the IFL distributions obtained from the Fe3+ -Py-DHR123 NC-RFG using a
290 MeV/nucleon 12 C6+ ion beam for various entrance
surface doses (ESDs). The distributions in (b) were
determined by subtracting the pre-exposure distribution and dividing by the ESD. These plots demonstrate
good agreement with one another, and the correlation coeﬃcient (R2 ) of IFL versus dose was greaterthan 0.995 even near the Bragg peak, as shown in(c). Figure 1(d) presents a comparison of the relativeδIFL /ESD and absorbed dose distributions as evaluated through a standard method of dosimetry using
an ionization camber (IC). These data conﬁrm thatthe relative δIFL /ESD distribution closely matched thedose distribution. Although the LET value increased
to 266 eV/nm at the Bragg peak, the sensitivity wasalmost constant.4)

Fig. 1. Radiological properties of NC-RFG after irradiation
with a carbon-ion beam (12 C6+ 290 MeV/nucleon).4)

NC-RFG resulted in a signiﬁcant reduction in theunwanted eﬀect of the LET. The promotion of Fentonlike reactions decomposed H2 O2 (the main product of
the high-LET ion radiolysis of water) and thus en-

Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 56 (2023)

hanced the oxidation reaction of DHR123. For the ﬁrst
time, this proposed dosimeter allows an evaluation of
the depth dose proﬁle when using a carbon-ion beam
at a typical therapeutic dose level of several Gy without the need to perform sensitivity corrections basedon LET.4)
References
1) T. Maeyama et al., J. Phys. Chem. B 121, 4238 (2017).
2) T. Maeyama et al., Sens. Actuators A Phys. 298,
111435 (2019).
3) T. Maeyama et al., J. Photochem. Photobiol. A 418,
113423 (2021).
4) T. Maeyama et al., Med. Phys. 50, 1073 (2023).

2- S42 -

Ⅰ. HIGHLIGHTS OF THE YEAR
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Variability in the net ecosystem productivity (NEP) of seaweed farms†
Y. Sato,∗1,∗2 G. N. Nishihara,∗3 A. Tanaka,∗4 and D. F. C. Belleza∗3
The critical role of vegetated ecosystems in carbon sequestration has attracted substantial interest across various disciplines. With growing evidence of the potential of macroalgae ecosystems to capture carbon, there
is burgeoning interest in applying newfound knowledge ofcarbon capture rates to better understand this potential
for carbon sequestration. Seaweed farms are expected toplay a signiﬁcant role in carbon capture; advocates for
expanding seaweed farms are increasing in many countries.
In general, seaweed farms are expected to be highly
productive, although whether they are autotrophic or
heterotrophic ecosystems and hence their potential as exporters of carbon is under debate. All in all, we present
our investigation on three seaweed farms, two Undaria
pinnatiﬁda (Wakame) farms in northern Japan (Matsushima Bay and Hirota Bay) and one Cladosiphon okamuranus (Mozuku) farm in southern Japan (Bise Point).
In addition, data were collected from two natural seaweed ecosystems (Arikawa Bay and Omura Bay) and one
degraded seaweed ecosystem (Tainoura Bay) in Nagasaki
Prefecture. We examined the frequency of autotrophic
days and compared potential carbon capture rates fromthese six geographic locations across Japan.
We estimated potential carbon capture rates by calculating the net ecosystem productivity (NEP) from continuous recordings of dissolved oxygen concentrations
under natural environmental conditions. Water temperature and dissolved oxygen concentrations were recordedwith dataloggers at a rate of one sample every ten minutes. In the natural and degraded ecosystems, one datalogger was placed directly above the sediment, another
50 cm above the sediment, and a third 50 cm below thewater surface (i.e., a total of three instruments and amean depth of 3 m for Omura Bay, 5 m for Arikawa
Bay, and 8 m for Tainoura Bay). The dataloggers at
the seaweed aquaculture farms were placed on the cultivation ropes and 1 m (Bise Point) and 2 m (Hirota
Bay and Matsushima Bay) below the cultivation ropes(i.e., a total of two instruments). The instruments wereplaced so that the majority of the biomass of the seaweed
was between the data loggers. Recordings were carriedout for four to twenty days before the instruments wereretrieved for maintenance and data oﬄoading. Calculations of productivity were based on the ensemble meanof the dissolved oxygen time series recorded by the dataloggers to account for vertical heterogeneity. The grossecosystem production (GEP) rates and ecosystem respiration (ER) rates were estimated from the diurnal ﬂuc†

∗1
∗2
∗3
∗4

Condensed from the article in Front. Mar. Sci. 9, 861932 (2022)
RIKEN Nishina Center
Riken Food Co., Ltd.
Organization of Marine Science Technology, Nagasaki University
Faculty of Science, University of Ryukyus

Fig. 1. Observed (colored points) and conditional mean of
the net ecosystem production (black symbols) rates ofthe study sites. The black horizontal lines indicate the
95% highest density credible interval of the predicted values. Hirota Bay and Matsushima Bay are Wakame farms,
Bise Point is Mozuku farm, Arikawa Bay and Omura Bay
are sites of the natural Sargassum spp. ecosystem, andTainoura Bay is a site where a seaweed ecosystem has degraded. The net ecosystem production in O2 and C are
calculated assuming a 1 to 1 molar ratio.

tuations of the dissolved oxygen concentration with the
open-water method (e.g., Hinode et al., 2020). Brieﬂy,
the NEP rate can be deﬁned as NEP = GEP + ER.
The NEP rates for the natural ecosystems in Arikawa
Bay and Omura Bay were equivalent to 0.043 and0.054 [g C m−2 d−1 ] m−1 , respectively (Fig. 1). Consering for the degraded ecosystem in Tainoura Bay, it
was −0.01 [g C m−2 d−1 ] m−1 . We noticed that the
Wakame farm in Matsushima Bay experiences autotrophy more often than natural ecosystems, although autotrophy of the Wakame farm in Hirota Bay and Mozuku
farm at Bise Point was less frequently observed. Nevertheless, up to 14.1 g C m−2 (0.110 g C m−2 d−1 ) was
captured by the production of Wakame and 3.6 g C m−2(0.034 g C m−2 d−1 ) was captured by Mozuku, and thetotal yield of carbon captured during 2021 productionseason for these farms was 43,385 kg C. Seaweed farms
are still highly valuable for their contribution to thelivelihood of coastal communities and have lesser detrimental impact on the environment than other forms ofaquaculture (e.g., Visch et al., 2020). We believe thatthe potential for carbon capture will not be homogenous
across species and location, and that more studies oncarbon ﬂux at organismal and ecosystem scales remain
to be conducted.
References
1) K. Hinode et al., Phycol. Res. 68, 298 (2020).
2) W. Visch et al., J. Appl. Phycol. 32, 3199 (2020).

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

1. Nuclear Physics

Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

RI beam production at BigRIPS in 2022
H. Suzuki,∗1 N. Fukuda,∗1 H. Takeda,∗1 Y. Shimizu,∗1 M. Yoshimoto,∗1 Y. Togano,∗1 N. Inabe,∗1 K. Kusaka,∗1
M. Ohtake,∗1 Y. Yanagisawa,∗1 H. Sato,∗1 K. Yoshida,∗1 and N. Fukunishi∗1Here, the radioactive-isotope (RI) beams produced
at the BigRIPS fragment separator1) in 2022 are presented. The experimental programs involving the useof BigRIPS during this year and the RI beams produced for each experiment are summarized in Table 1.
In the spring beamtime, a 238 U-beam campaign was
conducted, followed by another with a 78 Kr beam. The
238
U-beam campaign was divided into two parts: a series of director’s Discretionary Allocation (DA) programs with low-intensity (∼10 particle nA) primarybeams, and experimental programs with full-intensity(∼70 particle nA) beams.
The ﬁrst part of the 238 U-beam campaign began in
March. The performance of a newly developed ionization chamber (IC) specialized in heavy-mass beams
with a Xe-based gas was examined with the primary beam, energy-degraded 238 U beams, a 210 Rn84+ centered cocktail beam, and an A/Q = 2.5 setting
beam with wide range of atomic number Z = 30–90.2)
Then, a production test of a 237 Np beam was performed for the DA to investigate the energy dependence of its production cross section. The energy ofthe 238 U beams for this DA was degraded via the useof degraders located at T11 in the primary beamline,
not at F1 or F5. For the next DA in the search for unusual nuclear pathways in nuclear synthesis, 300- and70-MeV/nucleon 238 U beams were supplied. Subsequently, 225 Ac-centerd cocktail beams were produced
for their production cross-section measurement. Thesebeams were also supplied for the following DA of
PALIS. Thereafter, the IC test with P10 and CH4 gases
were performed2) with the same beams as in the previous IC test. Energy measurement of the 238 U primarybeam was conducted using the primary and energydegraded 238 U beams. This DA was performed for an
application of SRC as the world’s highest-beam-energy
cyclotron as per the Guinness Book of Records. For
the ﬁnal DA, 99 Tc was produced for the measurementof its transmutation cross section.
The second part of the 238 U-beam campaign began
in April, 1.5 days after the accelerator tunning. First,
a 79 Ni-centered cocktail beam was supplied for multireﬂection time-of-ﬂight mass spectrometer (MRTOFMS) experiment at F11. Subsequently, a Machine
Study (MS) and an experiment for the nucleosynthesisin r-process were conducted using OEDO with 124 Sn,
130
Te, and 130 Sn beams whose energies were adjusted
to be 180 MeV/nucleon in BigRIPS. A 202 Re-centeredcocktail beam was produced for the second MRTOFMS experiment to measure the mass in vicinity of the∗1

neutron magic number N = 126 region. A tertiary
spin-aligned 99 Zr beam at F7 was produced from thesecondary 100 Zr beam impinging on a wedge-shaped
Al target at F5 for an experiment to measure thequadrupole moment of an isomeric state of 99 Zr. Finally, a MS for production cross-section measurements
was conducted with 132 Sn-, 138 Te-, 144 Xe-, 150 Ba-, and154
Ce-centered cocktail beams.3) In addition, an autoPID system was tested with the 132 Sn setting in thisMS.4)
The 78 Kr-beam campaign began in May. An OEDO
experiment to study vp-process nucleosynthesis was
conducted with 56 Ni and 58 Ni beams. During changesof the magnet conﬁgurations and detector setups in
OEDO, two MSs were performed. The ﬁrst MS was fora development of automatic ion-optics tuning in the
primary beam line with low-intensity primary beam.
The second one was for production cross-section measurements with 64 As-, 39 Ca-, 37 Ca-, and 35 Ca-centeredcocktail beams.5) Subsequently, mass measurements
around the proton-drip line using SHARAQ were performed with 50 Fe-, 46 Fe-, and 23 Si-centered cocktail
beams.
During the autumn beam time, the 70 Zn campaign
was conducted from December following the repair ofthe large helium refrigerator in BigRIPS. During the
BigRIPS tuning, the performance of a new DAQ system with Mesytec MDPP-16 module for germaniumdetectors array for isomer tagging was examined witha 52 Ca-centered cocktail beam.6) Then, a 50 Ca beam
was produced for an OEDO experiment, wherein the
single-particle structure of 51 Ca was studied. During
this experiment, a severe problem occurred on the SRC
cyclotron caused the beam time to stop. Consequently,
the other scheduled experiment was postponed.
RI beam production at BigRIPS from the start ofthe operation in March 2007 is summarized in our
database7) available at https://ribeam.riken.jp/ .
References
1) T. Kubo, Nucl. Instrum. Methods Phys. Res. B 204, 97(2003).
2) M. Yoshimoto et al., in this report.
3) Y. Shimizu et al., in this report.
4) Y. Shimizu et al., in this report.
5) H. Suzuki et al., in this report.
6) H. Takeda et al., in this report.
7) Y. Shimizu et al., Nucl. Instrum. Methods Phys. Res. B
463, 158 (2020).

RIKEN Nishina Center-1-Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)

Table 1. List of experimental programs with RI beams produced at the BigRIPS separator in 2022.

Primary beam (Period)

238
U
345 MeV/nucleon(Mar. 21 – May 31)

238U
345 MeV/nucleon(Apr. 2 – Apr. 20)Kr
345 MeV/nucleon(May 16 – Jun. 3)
78

Zn
345 MeV/nucleon(Dec. 5 – Dec. 11)
702

Proposal No.

Spokesperson

CourseMS-EXP21-10

M. Yoshimoto

BigRIPS

DA21-03-01
DA21-05-01
DA21-08-01
DA21-07-01

H. Otsu
D. Suzuki
T. Sumikama
T. Sonoda

F12
F12
BigRIPS
PALIS

MS-EXP21-11

M. Yoshimoto

BigRIPS

DA21-09-01
DA21-04-02
NP2012-RIBF202-03
NP1912-SHARAQ18-01
MS-EXP22-01
NP2012-RIBF199-03
NP1912-RIBF175-01
MS-EXP22-04
NP1912-SHARAQ19-01
MS-EXP22-03
MS-EXP22-02
NP1812-SHARAQ13-01

H. Okuno
H. Otsu
M. Rosenbusch
N. Imai
N. Imai
M. WadaY. Ichikawa
Y. Shimizu
D. Suzuki
T. Nishi
H. Suzuki
S. Michimasa

BigRIPS
ZeroDegree
ZeroDegree
SHARAQ
SHARAQ
ZeroDegree
ZeroDegree
BigRIPS
SHARAQBigRIPSBigRIPS
SHARAQ

NP1812-SHARAQ12R1-01

K. Wimmer

SHARAQ-2-

RI beams
primary, energy-degraded 238U,
A/Q=2.5, 210Rn84+
237
Np
300, 70-MeV/nucleon 238U
225
Ac
225
Ac
primary, energy-degraded 238U,
A/Q=2.5, 210Rn84+
primary, energy-degraded 238U
99
Tc
79
Ni
124
Sn, 130Te, 130Sn
124
Sn, 130Te, 130Sn
202
Re
100
Zr99Zr
132
Sn, 138Te, 144Xe, 150Ba, 154Ce
56
Ni, 58Ni
primary64
As, 39Ca, 37Ca, 35Ca
50
Fe, 46Fe, 23Si
Ca

50

Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production cross-section measurements for very-neutron-deﬁcient Ca
and As isotopes produced from a 78 Kr beam at 345 MeV/nucleon by
BigRIPS separator
H. Suzuki,∗1 N. Fukuda,∗1 H. Takeda,∗1 Y. Shimizu,∗1 M. Yoshimoto,∗1 Y. Togano,∗1 T. Sumikama,∗1
K. Kusaka,∗1 and K. Yoshida∗1
We performed production cross-section measurements using a 78 Kr primary beam for the neutrondeﬁcient region around 20 Ca and 33 As isotopes, whosecross sections were not measured in previous 78 Kr campaigns in 2015 or 2019. The radioactive isotopes (RIs)
were produced by the projectile fragmentation of the
400-particle nA primary beam at 345 MeV/nucleon
impinging on a 5-mm-thick Be target in the BigRIPS
separator. Particle identiﬁcation based on the TOFBρ-∆E method1) was performed in the second stageof BigRIPS.
The production cross sections were deduced from themeasured production rates at the F7 focal plane andtheir transmission eﬃciencies in the separator, whichwere simulated with the LISE++ codes.2) In the simulation, the momentum distribution was represented byan assymetrical Gaussian distribution instead of thedefault distribution, i.e., Universal parameterization,3)
which is a combination of a Gaussian distribution inhigh momentum side and an exponential tail in low
momentum side. In the asymmetric Gaussian distribution, the Fermi momentum σ0 and asymmetry coefﬁcient α2) were set to be 134.1 MeV/c and 9% (preliminary), respectively, obtained from ﬁtting results ofthe experimental momentum distribution.
Figure 1 shows the production cross sections of RIs
obtained in this study (colored symbols) and the previous measurements (black symbols) under the assumption that their lifetimes are long enough compared to
the TOF values through the separator (∼460 ns). The
cross sections vary smoothly and exhibit natural behavior, except for 68 Br. The apparent small crosssection of 68 Br could be caused by a decay loss in theseparator due to its very short lifetime. K. Wimmer etal.4) reported a lifetime of 45–57 ns for 68 Br produced
from neighboring RI beams by secondary fragmentation reaction under the assumption of a systematiccross section of 68 Br. Assumming this lifetime value,
the cross section of 68 Br from 78 Kr beam is estimatedto be ∼10−5 mb and is on the systematics of the neighboring nuclei. The solid, dashed, and dotted lines show
the cross sections predicted by semi-empirical formulae
FRACS1.1,5) EPAX3.1a,6) and EPAX2.15.7) Overall,
FRACS1.1 provides better agreement with the measured cross sections than the other formulae; however,around the very-neutron-deﬁcient region, the discrepancy between the measured and predicted cross sec∗1

Fig. 1. (Preliminary) Measured production cross sections of RIs produced in the 78 Kr + Be reaction at
345 MeV/nucleon with semi-empirical cross-section formulae: (a) results for even-Z isotopes; (b) results for
odd-Z isotopes.

tions becomes larger. A detailed analysis is currently
in progress.
References
1) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).
2) O. B. Tarasov et al., LISE++ site, Michigan State University, https://lise.nscl.msu.edu .
3) O. B. Tarasov, Nucl. Phys. A 734, 536 (2004).
4) K. Wimmer et al., Phys. Lett. B 795, 266 (2019).
5) B. Mei, Phys. Rev. C 95, 034608 (2017).
6) K. Sümmerer, Phys. Rev. C 86, 014601 (2012).
7) K. Sümmerer et al., Phys. Rev. C 61, 034607 (2000).

RIKEN Nishina Center-3-Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Production cross-section measurements of neutron-rich nuclei in thenortheast region of 132 Sn by the in-ﬂight ﬁssion of a 238 U beam at
345 MeV/nucleon
Y. Shimizu,∗1 N. Fukuda,∗1 H. Takeda,∗1 H. Suzuki,∗1 M. Yoshimoto,∗1 Y. Togano,∗1 N. Inabe,∗1 K. Kusaka,∗1
M. Ohtake,∗1 Y. Yanagisawa,∗1 and K. Yoshida∗1
The systematic trends of production cross-sections
are essential to predict not only the production rates ofrare isotopes but also their purities and total rates. We
measured the production cross-sections in the neutronrich region with the atomic numbers Z = 49–57, located northeast of 132 Sn in the nuclear chart. The ﬁssion fragments produced via in-ﬂight ﬁssion of a 238 U
beam were separated and identiﬁed in ﬂight using the
BigRIPS separator. We ran four diﬀerent separator
settings, used with 132 Sn, 138 Te, 144 Xe, and 150 Ba as
central particles. The particle identiﬁcation (PID) was
performed using the TOF-Bρ-∆E method.1) Figure 1
shows the PID plot summed over the four diﬀerent
separator settings.

Fig. 2. Production cross-sections for each isotope from
238
U+Be reaction at 345 MeV/nucleon. The ﬁlled andopen symbols represent the production cross-sections of
this work and previous experiments,3–5) respectively.
The blue solid lines show the cross-sections predictedby the LISE++ AF model.2)

transmission eﬃciency. Our results are in good agreement with previous ones. The blue solid lines show thecross-sections predicted using the LISE++ abrasion ﬁssion (AF) model.2) The measured cross-sections haveplateaued as the mass number decreases, and the AF
model predictions reproduce those in this region fairly
well. On the other hand, the AF model predictions
underestimate the measured cross-sections in the very
neutron-rich region.
Detailed analysis is currently in progress.

Fig. 1. PID plot for ﬁssion fragments produced in the
238
U+Be reaction at 345 MeV/nucleon.

Figure 2 shows the production cross-sections foreach isotope as a function of mass number in thiswork (ﬁlled symbols) and the previous experiments3–5)(open symbols). The measured production cross sections were derived from the measured production rates
and transmission eﬃciencies in the BigRIPS separator, which were based on the LISE++ simulations.2)
The systematic uncertainty of the cross-sections is estimated to be ∼40%. The error is dominated by theuncertainties of the primary beam intensity and the∗1

References
1) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).
2) O. B. Tarasov et al., Nucl. Instrum. Methods Phys. Res.
B 266, 4657 (2013).
3) T. Ohnishi et al., J. Phys. Soc. Jpn. 79, 073201 (2010).
4) Y. Shimizu et al., J. Phys. Soc. Jpn. 87, 014203 (2018).
5) N. Fukuda et al., J. Phys. Soc. Jpn. 87, 014202 (2018).

RIKEN Nishina Center-4-Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production of 237 Np from 238 U beam at BigRIPS
C. Fukushima,∗1,∗2 R. Matsumura,∗2,∗3 D. Nishimura,∗1,∗2 H. Otsu,∗2 H. Wang,∗4 H. Baba,∗2 N. Fukuda,∗2
T. Isobe,∗2 K. Kokubun,∗5,∗2 M. Kurata-Nishimura,∗2 S. Meigo,∗6 T. Nishi,∗2 H. Sakurai,∗2 M. Sasano,∗2
H. Sato,∗2 Y. Shimizu,∗2 T. Sumikama,∗2 H. Suzuki,∗2 H. Takahashi,∗1 H. Takeda,∗2 J. Tanaka,∗2
Y. Togano,∗2 K. Yoshida,∗2 and M. Yoshimoto∗2
A variety of unstable nuclear beams with atomic
numbers (Z) up to 92 can be produced by the projectile fragmentation and in-ﬂight ﬁssion from highintensity U beams at RIBF. Recently, it was found that234–238
Np can be created by a proton pickup reaction
on 1 GeV/nucleon 238 U beam.1) Owing to the recent
developments of the high-Z beams at BigRIPS,2,3) energy dependence of the proton pickup reaction on 238 U
can be obtained at RIBF. Thus, we conducted an experiment to determine the energy dependence of the
production cross section of 237 Np. A test of the production of Np isotopes was performed by using the BigRIPS spectrometer at RIBF in March 2022.
Secondary beams around Z = 90 were produced by a238
U beam with energies of 345 and 250 MeV/nucleon4)
impinging on a 1-mm-thick 9 Be production target at F0
in BigRIPS. To reduce ambiguity of production crosssection, no degraders for separation were inserted in
the F1/F5 dispersive focal planes. The particle identiﬁcation (PID) of the secondary beam was performed
using the TOF-Bρ-∆E method.5) Plastic scintillators
at F3 and F7, and parallel-plate avalanche counters(PPACs) at F3, F5, and F7 were installed, respectively.
As no materials were installed at F1, charge states ofions were unchanged between F0 and F3. The conﬁguration of the BigRIPS was optimized for the production of a 237 Np beam, with magnetic rigidity Bρ values at D1, D2, D3-D4, and D5-D6 set to optimized forfully-stripped, fully-stripped, H-like, and He-like 237 Np
ions, respectively. Further, newly developed ionizationchamber (IC) with xenon-based gas was utilized at F7
for better separation of Z at high-Z region.6)
Figure 1 shows a PID plot of Z vs. A/Q, with typicalrelative A/Q and Z resolutions of 0.057% and 0.43% in
1σ, respectively. Calibrations of A/Q and Z were conducted using primary beams of 238 U90+,91+ that had
passed through the 1-mm-thick Be target. Even with
the new IC, the blobs, corresponding to nuclides of incoming beam, are not clearly separated. To validate
the production of the 237 Np91+ , a two-dimensional (2D)
Gaussian ﬁtting approach was conducted in accordancewith the distribution patterns of neighboring ions of
234 90+ 235 90+
U , U , and 232 Pa89+ . Figure 2(a) shows theexperimental data and the ﬁtted distribution by the 2D
Gaussian function in color lego and red mesh, respec∗1
∗2
∗3
∗4
∗5
∗6

Fig. 1. Particle identiﬁcation plot of Z vs. A/Q for fragments produced in the 345-MeV/nucleon 238 U. The
box region around 237 Np91+ was used for the twodimensional ﬁtting approach (see Fig. 2).

Fig. 2. (a) 3D-lego plots of PID around 237 Np91+ in the box
region of Fig. 1. (b) Residual by subtracting the ﬁtted
distribution from the experimental data.

tively. By subtracting the ﬁtted distribution from theexperimental data, the residuals were deduced and arepresented in Fig. 2(b). As evident the blob of 237 Np91+
at Z = 93 and A/Q = 2.604. As shown in Fig. 2(b), it
was found that 237 Np91+ can be counted up with contaminated U/Pa isotopes using the 2D Gaussian ﬁtting
technique. In the future, we plan to determine the production cross section by examining the beam amountand transport eﬃciency. We are also planning to analyze the data of 250 MeV/nucleon to discuss the energy
dependence of the production cross section.
References
1) E. Casarejos et al., Phys. Rev. C 74, 044612 (2006).
2) T. Sumikama et al., Nucl. Instrum. Methods Phys. Res.
B 463, 237 (2020).
3) N. Fukuda et al., RIKEN Accel. Prog. Rep. 54, 81(2021).
4) H. Otsu et al., in this report.
5) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).
6) M. Yoshimoto et al., in this report.

Department of Natural Sciences, Tokyo City University
RIKEN Nishina Center
Department of Physics, Saitama University
RIKEN HENP Laboratory
Department of Physics, University of TokyoJapan Atomic Energy Agency-5-Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Search for the double Gamow-Teller giant resonance using double
charge exchange reaction
A. Sakaue,∗1 T. Uesaka,∗2 and K. Yako∗1 for the RIBF-141R1 Collaboration∗1∗2

Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center-6-

preliminary
20

48

Ca(12C, 12Be(0+2))
250 MeV/nucleon
0 < θ < 0.3 deg

15

dσ/dΩdE [a.u.]

The double Gamow-Teller (DGT) transition is the nuclear process where the spin and isospin are changed
twice by a (στ )2 operator, where σ and τ are the spin
and isospin operators, respectively. It is theoretically
predicted that there is a giant resonance which occupies
most of the whole DGT transition strength in a highexcitation energy region.1) This resonance, called the
DGT giant resonance (DGTGR), remains undiscovered
experimentally. The observable of the DGTGR such as
the strength or the width will provide information about
the two-phonon excitations with spin-dependent correlations. In addition, it is suggested that such observables
will give a constraint to the nuclear matrix element of
neutrinoless double β decay, which has a large ambiguity in the current theoretical calculation.2)
We observe DGTGR using the double charge exchange
reaction (12 C, 12 Be(0+2 )) at RIBF. We employ an experimental method developed in the pionic atoms spectroscopy3) using a part of BigRIPS, from the F0 focal
plane to the F5 focal plane, as a spectrometer. A reaction target at F0 is bombarded with the primary beamof 12 C and the (12 C, 12 Be(0+2 )) reaction is induced. The
momentum of the ejected particle is obtained by measuring the position at F5 and thus the excitation energyof the residual nucleus of F0 is deduced. To select eventswith spin-ﬂip mode, 12 Be is transported to the stopperof 9 Be at F8 and delayed γ rays deriving from 12 Be(0+2))
decaysinto
thegroundare detected by DALI2; 12 Be(0+2state by emitting an electron-positron pair with the lifetime of 331 ± 12 ns.4)
We successfully detected the delayed-γ rays from
12
48
Be(0+
Ca target at F0 in the experiment2 ) for the
conducted at RIBF in May 2021 using this method forthe ﬁrst time.5) The signal-to-background ratio is estimated to approximately 5 : 1 for the events with photonsof 500 ± 100 keV detected in DALI2. It is improved fromthe one of the pilot experiment performed at RCNP, approximately 1 : 1.6)
The preliminary spectrum of the position at F5 forthe measurement of the 48 Ca target is shown in Fig. 1.
Here the event selection is such that the timing of thephoton is between 20 ns and 700 ns after from the timing of prompt γ-rays, and the energy is in the regionof 510 ± 100 keV. Each color corresponds to the scattering angle of 12 Be at F0 target in the laboratory system, which is reconstructed from the position and theangle measured at F5, within 0.0–0.3◦ (blue line, blue
hatched), 0.3–0.6◦ (red line, green hatched), and 0.6–
0.9◦ (black line, black hatched). In this spectrum, thekinematical position aberration with the scattering an-

0.3 < θ < 0.6 deg
0.6 < θ < 0.9 deg

10

5

0
−80
48

Ti Eex [MeV]

−60

−40
−20
F5x [mm]
40

0

20
20

Fig. 1. Preliminary result of position measured at F5. Lineand hatching colors correspond to selected regions of scattering angles: 0–0.3◦ (blue line, blue hatched), 0.3–0.6◦(red line, green hatched), and 0.6–0.9◦ (black line, blacked
hatched).

gle is corrected for. The preliminarily calibrated energyof 48 Ti is shown below the ﬁgure. The energy resolution
and the angular resolution was evaluated as 1.6 MeV
and 0.17◦ , respectively. The main background is an accidental coincidence of 12 Be and γ rays from room backgrounds. The amount of the background is estimated toabout 5% with the event selection by the gate of DALI2
described above. This background is subtracted by assuming that its energy spectrum is same as events thatare not gated by DALI2. In the region of the position
from −10 mm to 0 mm, which corresponds to aboutfrom 23 to 30 MeV in the excitation energy where the
DGTGR is expected to be observed2) , there seem to beenhancements at −2 mm and −8 mm especially in theforward angle, though statistics are limited. The structure around −20 mm, on the other hand, is likely due
to the events of the 12 C(12 C, 12 Be)12 Og.s. reaction fromthe graphene sheet attached to the 48 Ca target.
In order to interpret the structure, we are now working
on the comparison of the angular distribution with thecalculated ones.
References
1) N. Auerbach et al., Annu. Phys. 192, 77 (1989).
2) N. Shimizu et al., Phys. Rev. Lett. 120, 142502 (2018).
3) T. Nishi et al., Nucl. Instrum. Method Phys. Res. B 317,
290 (2013).
4) S. Shimoura et al., Phys. Lett. B 654, 87 (2007).
5) A. Sakaue et al., RIKEN Accel. Prog. Rep. 55, 9 (2022).
6) M. Takaki et al., CNS Annu. Rep. 2016, CNS-REP-96, 3(2018).

Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023) Retracted on February 1, 2024

RIKEN Accel. Prog. Rep. 56 (2023)

Development of dispersion matching optics in OEDO beamline
S. Hanai,∗1 S. Michimasa,∗1 T. Chillery,∗1 S. Ota,∗1 N. Imai,∗1 S. Shimoura,∗1 N. Fukuda,∗2 Y. Hijikata,∗3,∗2
K. Kameya,∗4,∗2 S. Kitayama,∗4,∗2 K. Kishimoto,∗5,∗2 K. Kusaka,∗2 J. Li,∗1 Y. Maeda,∗6,∗2 Y. Maruta,∗4,∗2
T. Matsui,∗4,∗2 K. Miki,∗4,∗2 D. Nagae,∗2 H. Nishibata,∗5,∗2 D. Nishimura,∗7,∗1,∗2 M. Sasano,∗2 Y. Shimizu,∗2
S. Sugawara,∗2 T. Sumikama,∗2 H. Suzuki,∗2 H. Takahashi,∗7 H. Takeda,∗2 T. Uesaka,∗2 R. Urayama,∗4,∗2
T. Wakasa,∗5 K. Yako,∗1 Y. Yamaguchi,∗2 Y. Yanagisawa,∗2 N. Yokota,∗5,∗2
C. Yonemura,∗5,∗2 and K. Yoshida∗2tectors, a parallel-plate avalanche counter and a lowpressure multiwire drift chamber, were placed at thefoci from F3 to S2, to measure the transfer matrix elements at each focal plane. We veriﬁed the consistencyof the measured matrix elements by comparison withion optics calculation results.
By evaluating the matrix elements, the momentum
dispersion at S0 was deduced as 16.3 m, which corresponds to a dispersion of 0.025 mm/% and satisﬁes the lateral dispersion matching condition with the
SHARAQ spectrometer. Figure 2(a) shows that there
is no correlation between the horizontal position (momentum dispersion) at S0 and that at S2 and therefore,
the condition of momentum dispersion matching is fulﬁlled. Figure 2(b) shows the correlation between thehorizontal position (momentum dispersion) at S0 andthe horizontal angle at S2, which suggests that angular dispersion matching is eﬃciently satisﬁed. We conclude that angular momentum dispersion matching is
also achieved at S2.

S0 horizontal Position [mm]

The Optimized Energy Degrading Optics (OEDO)
beamline provides potential opportunities to perform
nuclear physics experiments with spatially and achromatically well-forcused low-energy RI beams1) or highmomentum resolution by selecting a suitable ion transportation method. High-quality low-energy RI beam
production has been achieved.2) Recently, several
beamline magnets in the OEDO beamline were rearranged aiming at the realizing a high momentum resolution. To conduct nuclear spectroscopy with a resolution
greater than the energy width of the incident beam, lateral and angular momentum dispersion matching techniques are essential. Figure 1 shows a designed dispersion matching ion optics from BigRIPS F3 to SHARAQ
S2 foci through the OEDO beamline. The S0 intermediate focus, where a target will be inserted in a future
experiment, has the largest momentum dispersion in
the beamline of 14.7 m, and this momentum dispersion vanishes at the ﬁnal focus, S2. We report here astudy showing dispersion matching optics of the OEDO
beamline.

±
±
±

3
2
1

-

±
±

BigRIPSOEDO

Consequently, we achieved dispersion matching ion
transportation through the OEDO beamline. Using
this ion-optical mode, we plan to conduct an approved
experimental program of direct mass measurements ofvery rare RI nuclei.

We performed the study using an 82 MeV/nucleon
triton beam produced by the BigRIPS separator fromthe 200 MeV/nucleon 4 He primary beam. Position de∗2
∗3
∗4
∗5
∗6
∗7

S2 horizontal Angle [mrad]Fig. 2. (a) Correlation between S0 and S2 horizontal positions. (b) Correlation between S0 horizontal position
and S2 horizontal angle. (a|δ) term is approximately
0.4 mrad/%.

SHARAQ

Fig. 1. Trajectories of ion beam with dispersion matching
setting in BigRIPS-OEDO-SHARAQ beamline. Trajectories are calculated from ﬁrst-order matrix elements.

∗10

S2 horizontal Position [mm]Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center
Department of Physics, Kyoto University
Department of Physics, Tohoku University
Department of Physics, Kyushu University
Faculty of Engineering, University of Miyazaki
Department of Natural Sciences, Tokyo City University

References

1) S. Michimasa et al., Prog. Theor. Exp. Phys. 2019,
043D01 (2019).
2) S. Michimasa et al., CNS Annu. Rep. 2018, CNS, REP98-35 (2020).

-7-

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Single-particle states in fp-shell nuclei through 50 Ca(d, p)51 Ca
transfer reaction
C. Ferrera,∗1 K. Wimmer,∗2,∗3 D. Suzuki,∗3 N. Imai,∗4 M. Armstrong,∗5 T. Chillery,∗4 Y. Cho,∗6
M. Dozono,∗3,∗7 F. Endo,∗8,∗3 S. Escrig,∗1 N. Fukuda,∗3 T. Haginouchi,∗3,∗8 S. Hanai,∗4 S. Hayakawa,∗4
Y. Hijikata,∗3,∗7 J. W. Hwang,∗6 S. Ishio,∗3,∗8 A. Jungclaus,∗1 A. Kasagi,∗9,∗10 K. Kawata,∗4 N. Kitamura,∗4
R. Kojima,∗4 J. Li,∗4 S. Masuoka,∗4 S. Michimasa,∗4 B. Moon,∗6 K. Okawa,∗4 S. Ota,∗4,∗11 T. Saito,∗4
H. Sakurai,∗3 Y. Shimizu,∗3 S. Shimoura,∗3,∗4 Y. Son,∗6 T. Sumikama,∗3 H. Suzuki,∗3 H. Takeda,∗3
Y. Togano,∗3 J. Vesic,∗12 K. Yako,∗4 R. Yokoyama,∗4 K. Yoshida,∗3 and M. Yoshimoto∗3
Neutron-rich Ca isotopes towards neutron number
N = 34 are pivotal for exploring the evolution of the
f p-shell orbitals. Beyond the N = 28 shell gap in
48
Ca, new magic numbers at N = 32 and 34 were
established through spectroscopy of low-lying statesand mass measurements. Most recently, the spatial
extension of the 1f7/2 and 2p3/2 neutron orbitals wasdetermined via a one-neutron knockout reaction from
52Ca.1) However, the single-particle 2p1/2 and 1f5/2 orbitals deﬁning the shell gaps at N = 32, 34 remain tobe established experimentally. The one-neutron transfer reaction is an experimental method well-suited to
study low-spin single-particle orbitals. The cross section of this reaction gives access to the spectroscopic
factors, while the angular distribution of the reaction
products allows for deduction of the angular momentum transfer.
In December 2022, the SHARAQ12 experiment was
performed at RIKEN, aiming to study the singleparticle structure of 51 Ca via the (d, p) transfer reaction using an energy-degraded secondary 50 Ca beam.
The beam was produced at BigRIPS from a primary70
Zn beam at an energy of 345 MeV/nucleon fragmented on a Be target. For the energy degrading procedure, the 50 Ca beam was conducted to the OEDO2)
beamline, where a combination of an angle-tunablewedge-shaped degrader and an additional aluminum
ﬂat-plate degrader placed at FE9 successfully reduced
the beam energy to approximately 15 MeV/nucleon,
which improves the momentum matching of the reaction compared to the typical beam energies at RIBF.
Particle identiﬁcation based on the ToF-B ρ method
showed excellent isotope separation, is shown in Fig. 1,
where the 50 Ca beam can be clearly identiﬁed. Therefore, the use of the Radio-Frequency Deﬂector (RFD)

Fig. 1. Particle identiﬁcation in OEDO with horizontal position at FE9 and corrected time-of-ﬂight between F3
and FE9.

of OEDO was not required. The secondary target ofCD2 (260 µg/cm2 ) was placed at the SHARAQ spectrometer reaction chamber with the purpose of inducing one-neutron transfer reactions. The recoiling protons were measured with the detector setup TINA2,3)
consisting of a box of four TTT double-sided silicon
strip detectors backed by CsI crystals and a backward
annular YY1-type silicon strip detector array with CsI
crystals behind. The array was placed at laboratory
backward direction covering θlab = 95–165 deg (solid
angle 35% of 4π) which is the angular range most sensitive to the angular momentum transfer of the reaction.
The excitation energy of states populated will be determined from the measured missing mass of the reaction.
Heavy 51 Ca ejectiles were measured by the QQD spectrometer equipped with a set of Strip-Readout PPAC
detectors and an ionization chamber, so backgroundcoming from fusion reactions can be suppressed via
charge identiﬁcation. The analysis of excitation energies and angular distributions is ongoing.

∗1

Instituto de Estructura de la Materia, CSICGSI Helmholtzzentrum für Schwerionenforschung GmbH
∗3 RIKEN Nishina Center∗4 Center for Nuclear Study, University of Tokyo∗5 Institute of Nuclear Physics, University of Cologne∗6 CENS Institute for Basic Science∗7 Department of Physics, Kyoto University∗8 Department of Physics, Tohoku University∗9 Department of Physics, Gifu University∗10 RIKEN Cluster for Pioneering Research∗11 Research Center for Nuclear Physics, Osaka University∗12 Department of Low and Medium Energy Physics, Jožef Stefan Institute∗2

References
1) M. Enciu et al., Phys. Rev. Lett. 129, 262501 (2022).
2) S. Michimasa et al., Prog. Theor. Exp. Phys. 2019,
043D01 (2019).
3) P. Schrock et al., RIKEN Accel. Prog. Rep. 51, 20(2018).

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Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Study of νp-process nucleosynthesis at OEDO
D. Suzuki,∗1 B. Mauss,∗2 N. Imai,∗3 S. Michimasa,∗3 D. Beaumel,∗4,∗1 K. Y. Chae,∗5 S. Cherubini,∗6
T. Chillery,∗3 M. Dozono,∗7,∗1 M. Egeta,∗8,∗1 F. Endo,∗8,∗1 N. Fukuda,∗1 T. Haginouchi,∗8,∗1 S. Hanai,∗3
S. Hayakawa,∗3 Y. Hijikata,∗7,∗1 J. W. Hwang,∗9 S. Ishio,∗8,∗1 N. Iwasa,∗8,∗1 S. Kawase,∗10,∗1 K. Kawata,∗3
R. Kojima,∗3 S. Kubono,∗1 M. La Cognata,∗6 J. Li,∗3 N. Nishimura,∗1 K. Okawa,∗3 M. Oishi,∗10,∗1
H. J. Ong,∗11,∗1,∗12 S. Ota,∗12 S. Palmerini,∗13,∗14 R. Pizzone,∗6 T. Saito,∗3 H. Sakurai,∗1 S. Shimoura,∗3,∗1
Y. Shimizu,∗1 T. Sumikama,∗1 H. Suzuki,∗1 H. Takeda,∗1 H. Tanaka,∗15,∗1 M. Tanaka,∗1 X. Tang,∗12
T. Teranishi,∗15,∗1 Y. Togano,∗1 A. Tunimo,∗6 Y. Wang,∗16 K. Yako,∗3 K. Yahiro,∗7,∗1 H. Yamaguchi,∗3
R. Yokoyama,∗3 K. Yoshida,∗1 R. Yoshida,∗7,∗1 and M. Yoshimoto∗1
56

Neutron-deﬁcient stable isotopes, referred to as pnuclei, are known to be produced by p process nucleosynthesis. However, certain lighter p-nuclei, e.g. Mo
and Ru, are signiﬁcantly underproduced in the present
astrophysical scenario. The νp process1) ascribes their
origin to core-collapse supernovae, wherein the availability of neutrons aids the ﬂow to bypass the waiting
point 56 Ni on the synthesis path. The neutron capture
cross section of 56 Ni, howeve, remains experimentally
unknown because both the neutron and 56 Ni are shortlived. To evaluate the cross sections, we applied thesurrogate method2) to the (d, p) reaction by using anenergy-degraded 56 Ni beam at OEDO.
The experiment was performed at the OEDO beamline of RIBF. The secondary beam was produced by
the projectile fragmentation reaction of a 78 Kr beamat 345 MeV/nucleon and puriﬁed by the BigRIPS fragment separator. The total beam intensity at F3 wasmeasured to be about 500 kpps (particles per second)with a purity of about 30% for 56 Ni. The impurities
included 55 Co (50%) and 54 Fe (10%), both isotones of56
Ni with N = 28. The energy of 56 Ni transmitted
from BigRIPS to OEDO was about 113 MeV/nucleon.
The beam energy was degraded at FE9 by an angletunable wedge-shaped degrader (3 mm in central thickness) together with a ﬂat degrader (0.3 mm in thickness),3) both made of aluminum. The angle of theformer was set to 4 mrad to obtain a desired beamenergy. The beam energy of 56 Ni was estimated to
be 15.1(10) MeV/nucleon based on the time of ﬂight
measurement from FE9 to FE12. The RF deﬂector at
FE10 was operated at 100 kV to reduce the spot size of

Ni. The phase shift of RF was optimized to increase
the transmission through the target frame aperture of
50 mm in diameter (Fig. 1). The transmission from F3
to FE12 was about 75% with a total rate of 370 kpps
at FE12. CD2 targets of 285 and 644 µg/cm2 , provided by INFN, were set at S0 about 1 m downstreamof FE12. The incident position and angle of the secondary beam were deduced by a pair of SR-PPACs4)
in the vacuum chamber of FE12. The recoiling protons were detected by the silicon and CsI detectors
array TiNA.5) Missing mass spectra are deduced fromthe scattering angle and total kinetic energy measured
by TiNA. The scattered particles were transmitted toa QQD spectrometer at zero degrees for the particle
identiﬁcation, which facillitated the determination of
the decay channels. The spectrometer was equippedwith a pair of SR-PPACs followed by an ionizationchamber with CF4 gas at 100 Torr. The transmission
through the spectrometer was roughly 50%.

Fig. 1. Horizontal position at S0 vs. TOF from F3 to FE9of the secondary beam with the optimal RF settings.

∗1

RIKEN Nishina Center∗2 CEA-DAM∗3 Center for Nuclear Study, University of Tokyo∗4 IJClab, IN2P3, CNRS
∗5 Department of Physics, Sungkyunkwan Unviversity∗6 INFN Laboratori Nazionali del Sud∗7 Department of Physics, Kyoto University∗8 Department of Physics, Tohoku University∗9 CENS, Institute for Basic Science∗10 IGSES, Kyushu University∗11 Institute of Modern Physics, Chinese Academy of Sciences∗12 Research Center for Nuclear Physics, Osaka University∗13 INFN Sezione di Perugia∗14 Department of Physics, University of Perugia∗15 Department of Physics, Kyushu University∗16 Department of Physics, Tsinghua University

The data analysis is underway. The current focus isdirected towards the beam tracking detectors.
References
1) C. Fröhlich et al., Phys. Rev. Lett. 96, 142502 (2006).
2) N. Imai et al., submitted to Phys. Lett. B.
3) J. W. Hwang et al., RIKEN Accel. Prog. Rep. 53, 16(2020).
4) S. Hanai, Master thesis, University of Tokyo (2021).
5) B. Mauss et al., RIKEN Accel. Prog. Rep. 54, 114(2021).

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Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Study of 130 Sn(d, p) reaction in inverse kinematics for r-process
nucleosynthesis
N. Imai,∗1 S. Michimasa,∗1 T. Chillery,∗1 D. Suzuki,∗2 D. S. Ahn,∗3 A. Chae,∗4 S. Cherubini,∗5 M. La Cognata,∗6
M. Dozono,∗7,∗2 M. Egeta,∗8,∗2 F. Endo,∗8,∗2 N. Fukuda,∗2 T. Haginouchi,∗8,∗2 S. Hanai,∗1 S. Hayakawa,∗1
J. W. Hwang,∗3 Y. Hijikata,∗2,∗7 S. Ishio,∗8,∗2 N. Iwasa,∗8,∗2 K. Kawata,∗1 S. Kubono,∗2 R. Kojima,∗1 L. Lamia,∗5
J. Li,∗1 N. Nishimura,∗2 K. Okawa,∗1 H. J. Ong,∗9,∗10,∗2 S. Ota,∗10 S. Palmerini,∗11 R. G. Pizzone,∗6 T. Saito,∗1
Y. Shimizu,∗2 S. Shimoura,∗1,∗2 T. Sumikama,∗2 H. Suzuki,∗2 H. Takeda,∗2 A. Tumino,∗12,∗6 X. Tang,∗9
H. Tanaka,∗13,∗2 M. Tanaka,∗2 T. Teranishi,∗13,∗2 Y. Togano,∗2 R. Yokoyama,∗1 R. Yoshida,∗6,∗2 K. Yoshida,∗2
M. Yoshitomo,∗2 Y. Wang,∗14 and Z. Xiao∗14
The r-process nucleosynthesis is a major origin ofheavy elements beyond iron. Because of rich neutrons in
explosive astrophysical conditions, neutron-rich radioactive isotopes (RIs) are involved in the r-process. Though
the scenario of the r-process was proposed more thanﬁfty years ago, the astrophysical sites of the r-process
are still one of the biggest problems in physics. Nucleosynthesis simulations require precise nuclear-physics
inputs such as β decay rates, masses of the nuclei, andneutron capture rates, which can constrain the astrophysical conditions. However, as the neutron targets are
not available yet, it is impossible to measure the capture
cross sections and related rates directly. In the case of
the compound neutron-capture rates, since there are signiﬁcant uncertainties in the level density of the unboundstate and the γ emission probability from the highly excited state, the cross sections diﬀer by more than one
order of the magnitude even in the statistical model calculations.
We have evaluated the neutron capture reaction rate
on 79 Se with the surrogate reaction of 79 Se(d, p) in inverse kinematics, where the γ emission probabilities in
the unbound states of 80 Se have been determined bymeasuring the residual nuclei without detecting the γrays.1) The present study aims to determine the neutron
capture rate on 130 Sn via (d, p) reaction with a 130 Sn
beam. In addition, to evaluate the systematic error of
the method, (d, p) reactions on 130 Te and 124 Sn were alsomeasured.
The experiment was conducted at the OEDO beamline at RIBF. The cocktail beam including 130 Sn
was produced by the in-ﬂight ﬁssion of 238 U at
345 MeV/nucleon. The energy of the beam from F3
to FE9 was chosen to be around 170 MeV/nucleon. RI∗1

Center for Nuclear Study, University of Tokyo
RIKEN Nishina Center∗3 CENS, Institute for Basic Science∗4 Department of Physics, Sonkyunkwan University∗5 Department of Physics and Astronomy, University of Catania∗6 INFN, LNS∗7 Department of Physics, Kyoto University∗8 Department of Physics, Tohoku University∗9 Nuclear Physics Div. Institute of Modern Physics∗10 Research Center for Nuclear Physics, Osaka University∗11 INFN sezione di Perugia∗12 Faculty of Engineering and Architecture, Kore University of
Enna∗13 Department of Physics, Kyushu University∗14 Department of Physics, Tsinghua University∗2

beams were identiﬁed by the Bρ-TOF method. Figure 1
shows the particle identiﬁcation (PID) map of the secondary beam, demonstrating that 130 Sn beam is well separated from the other isotopes. Thanks to the new optics
developed in the MS22-1 and described elsewhere in thisvolume, the transmission between F3 and FE9 was improved to be 85% for the beam with the F1 momentum
slit of ±0.5%. The energy of the cocktail beam was further degraded to 20 MeV/nucleon by a combination of
the angle-tunable degrader and a ﬂat degrader.

Fig. 1. PID map of the secondary beams at FE9. See thetext for details.

The 130 Sn beam of around 150 kcps was focused on
the secondary target of 287 µg/cm2 -thick deuterated
polyethylene. The recoil protons were detected by the
TiNA2 array which was composed of four TTT doublesided square-shape Si detectors, six YY1 single-sided
sector-shape Si detectors, and sixteen CsI(Tl) detectors.
The four CsI(Tl) were placed behind each TTT to measure the ∆E-E correlation of the charged particles. The
outgoing residual nuclei were momentum-analyzed by
the D1 magnet of the SHARAQ spectrometer. Two SRPPACs and an ionization chamber were installed at theﬁnal focal plane to identify the residual nuclei. Analysisof the data is on going.
Reference
1) N. Imai et al., submitted to Phys. Lett. B.

- 10 -

Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Toward the mass measurement of neutron-rich nuclei in the vicinity of
N = 126 isotones with SLOWRI/ZD-MRTOF
H. Ishiyama,∗1 M. Wada,∗3 A. Takamine,∗1 M. Rosenbusch,∗3 J. M. Yap,∗1,∗6 V. H. Phong,∗1 S. Nishimura,∗1
S. Iimura,∗1,∗2 D. Hou,∗4,∗3,∗5 S. Chen,∗3,∗6 J. Liu,∗4 W. Xian,∗3,∗6 S. Yan,∗7,∗3 P. Schury,∗3 S. Kimura,∗1
T. Niwase,∗1,∗3 Y. Ito,∗9 T. Sonoda,∗1 T. M. Kojima,∗1 Y. X. Watanabe,∗3 Y. Hirayama,∗3 H. Miyatake,∗3
S. Naimi,∗1 S. Michimasa,∗10 A. Odahara,∗2 and S. Kubono∗1,∗10
Despite the ﬁrst observation of an r-process production site (GW170817) in 2017, conﬁrming neutron-starmergers as probably the most important site, many open
questions remain to understand r-process nucleosynthesis fully. A major unanswered question is whether neutron star merger r-process products alone can explain
the observed large scatter of Eu/Fe and other r-processelements at [Fe/H] < 3 metalicites.1) The shape and position of the 3rd peak on r-process element abundances
would serve as an anchor point to conﬁrm the reproducibility of the element abundances in the reaction
network calculations when investigating an astrophysical site for r-process nucleosynthesis. However, there is
no experimental data for nuclear physics inputs such as
masses, half-lives, and neutron branching ratios in thevicinity of N = 126 waiting point nuclei, which criticallyaﬀect the formation of the 3rd peak.2) Therefore, direct
mass measurement of neutron-rich nuclei in the vicinity
of N = 126 waiting point nuclei, which are considered tobe the progenitors for the 3rd peak formation, is strongly
desired.
RIBF199 experiment was performed to measure themasses of these nuclides with MRTOF in combination with an RF carpet type He gas cell (RFGC) of
SLOWRI installed at F11 of BigRIPS (ZD-MRTOF).3)
No neutron-rich nuclei in this region were observed with
ZD-MRTOF during the beam time. There are two possible reasons why we could not observe any RIs. One
possible reason was the ‘low’ extraction eﬃciency fromthe RFGC. Unfortunately, the ion guide was found to be
defective. Therefore, the RFGC chamber was opened,
and the ion guide replaced just before the beamtime.
We had no suﬃcient baking time to suppress contaminant molecules which reduces the extraction eﬃciency
due to various molecular formations of RI atoms. After our beamtime, the RFGC was long baked for about
10 days. Then, the extraction eﬃciency was examinedusing a 248 Cm ﬁssion source installed inside the RFGC.
The extraction eﬃciencies after stopping inside RFGC
∗1

RIKEN Nishina Center
Department of Physics, Osaka University∗3 Wako Nuclear Science Center (WNSC), IPNS, KEK∗4 Institute of Modern Physics, Chinese Academy of Science∗5 School of Nuclear Science and Technology, Lanzhou University∗6 Department of Physics, University of Hong Kong
∗7 Institute of Mass Spectrometer and Atmospheric Environment, Jinan University∗8 Department of Physics, Kyushu University∗9 Advances Science Research Center, Japan Atomic Energy
Agency∗10 Center for Nuclear Study, University of Tokyo∗2- 11 -

for the ﬁssion fragments such as Tc and Mo have been
recovered to be roughly 10%.
The second and most important reason is that yields
on RIs of interest provided by BigRIPS were too low.
Figure 1 shows the intensities of RIs measured in thisregion using BigRIPS/ZDS detectors. As shown in
Fig. 1, almost measured intensities for RIs of interest are
10−2 pps or less, roughly two orders of magnitude lower
than expected values estimated with LISE++. The production yield from uranium beam fragmentation seems
insuﬃcient to measure the masses in this region, even if
the extraction eﬃciency is recovered.

Fig. 1. Measured yields for RIs of interest at F11. The production reaction is 238 U + 9 Be with the beam energy of
345 MeV/nucleon and the intensity of 70 particle nA.

We are currently considering using lead beam fragmentation to produce RIs in this region. In the southwest part of N = 126 down to Z = 70, higher production
cross-sections are expected to be obtained with 208 Pb
beam than with 238 U beam.4) A Letter of Intent was
submitted to NP-PAC 2022 to request the developmentof a Pb beam at RIBF, and the PAC “enthusiasticallyendorsed” it. We hope to continue the experiment with
the Pb beam.
References
1) J. J. Cowan et al., Rev. Mod. Phys. 93, 015002 (2021).
2) M. R. Mumpower et al., Prog. Part. Nucl. Phys. 86, 86(2016).
3) M. Rosecbusch et al., Nucl. Instrum. Methods Phys. Res.
A 1047, 167824 (2023).
4) T. Kurtukian-Nieto et al., Phys. Rev. C 89, 024616(2014).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Q-moment measurement of isomeric state of 99 Zr
using spin-aligned beam
Y. Shinohara,∗1,∗2 Y. Ichikawa,∗1,∗2 S. Go,∗2 H. Nishibata,∗1,∗2 S. Ando,∗1,∗2 K. Asahi,∗2 H. Baba,∗2
N. Fukuda,∗2 G. Georgiev,∗2,∗3 A. Gladkov,∗2 K. Imamura,∗2 K. Kishimoto,∗1,∗2 R. Lozeva,∗2,∗3 M. Mukai,∗2
M. Niikura,∗2 Nurhaﬁza M. Nor,∗2,∗4 A. Odahara,∗2,∗4 Y. Shimizu,∗2 M. Si,∗2,∗3 K. Stoychev,∗3 H. Suzuki,∗2
M. Tajima,∗2 A. Takamine,∗2 H. Takeda,∗2 S. Takeshige,∗2,∗5 M. Tanaka,∗2 Y. Togano,∗2 H. Ueno,∗2
T. Wakasa,∗1,∗2 W. Yamashita,∗1,∗2 H. Yamazaki,∗2 M. Yoshimoto,∗2 and J. M. Daugas∗2,∗6
The 99 Zr nucleus with a neutron number N = 59 is
located at the border of a region where a sudden onset of ground-state deformation occurs for Zr isotopes
between N = 58 and 60.1) This change has been described as a quantum phase transition (QPT) with theneutron number as a control parameter. The 99 Zr nucleus closest to the critical point of the QPT has anisomer (99m Zr) with a spin parity of 7/2+ at 252 keV.
A recent measurement of its magnetic moment showeda surprising result. Namely, the 7/2+ state is not of
single-particle-like nature but rather collective.2) To
conﬁrm this collectivity directly, measurement of thequardupole (Q) moment of the same isomer was conducted.
The experiment was conducted at BigRIPS at RIBF
in April 2022. The two-step fragmentation schemewith the momentum-dispersion matching technique3,4)
was employed to produce a highly spin-aligned beamof 99 Zr. First, 100 Zn was produced by a ﬁssion reactionof a 345-MeV/nucleon 238 U beam on a 9 Be target witha thickness of 1.29 g/cm2 . The secondary 100 Zr beam
was impinged to a second target of wedge-shaped aluminum with a mean thickness of 0.810 g/cm2 and awedge angle of 2.65 mrad, placed at the momentumdispersive focal plane F5. The 99 Zr nuclei, including
those in isomeric state 99m Zr, were produced throughone-neutron removal from 100 Zr. The tertiary 99 Zr
beam was subsequently transported to F7 while matching the momentum dispersion of 99 Zr in F5–F7 to thatof 100 Zr in F3–F5. F7 slits with a width of ±10 mm
were used to extract the region around the center ofthe momentum distribution for 99 Zr.
Prior to the Q-moment measurement, the magnitude of spin alignment realized in 99m Zr was checkedby the time-diﬀerential perturbed angular distribution(TDPAD) methods. The TDPAD apparatus, placed at
F8, consisted of a dipole magnet, Cu crystal stopper,
Ge detectors, and plastic scintillator. The dipole magnet provided a static magnetic ﬁeld of B0 = 0.200 T.
99m
Zr was implanted into the Cu stopper, and γ rays
were detected with four Ge detectors placed on a plane
∗1
∗2
∗3
∗4
∗5
∗6

perpendicular to B0 at angles of ±45 and ±135 degrees
with respect to the beam axis. A plastic scintillator
with a thickness of 0.1 mm was placed upstream of the
stopper to provide the time-zero trigger.
The R(t) ratio, which represents the change of the γ
ray’s anisotropy synchronized with the spin precession,associated with the 130-keV γ ray deexciting 99m Zr was
obtained, as shown in Fig. 1. Preliminarily, the magnitude of spin alignment realized in this measurement
was found to be approximately 10%.
0.2

Preliminary
R(t)

0.1

0

-0.1

-0.2
200

400

600

800

1000

1200

Time (ns)Fig. 1. R(t) ratio associated with the 130-keV γ ray deexciting 99m Zr under a static magnetic ﬁeld. The magnitude of spin alignment was deduced from the amplitudeof the ocscillation.

For the Q moment measurement, the interaction between the Q moment and electric-ﬁeld gradient in asingle crystal of zyrconium metal was used to apply
the TDPAD method. The zyrconium crystal was set
so that the crystal axis was perpendicular to both thebeam axis and detector plane. The 99 Zr beam collimated to 10 mm ϕ was implanted into the stopper
crystal. Three Ge detectors were arranged at angles of
0 and ±90 degrees with respect to the beam axis. Data
analysis on the Q-moment measurement is in progress.
References

Department of Physics, Kyushu University
RIKEN Nishina Center
IJCLab, CNRS/IN2P3, Université Paris-Saclay
Department of Physics, Osaka University
Department of Physics, Rikkyo University
Institut Laue-Langevin

1) P. Campbell et al., Phys. Rev. Lett. 89, 082501 (2002).
2) F. Boulay et al., Phys. Rev. Lett. 124, 112501 (2020).
3) Y. Ichikawa et al., Nat. Phys. 8, 918 (2012).
4) Y. Ichikawa et al., Nat. Phys. 15, 321 (2019).

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Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

In-beam γ-ray spectroscopy of exotic 79 Cu with HiCARI
M. Kaci,∗1 S. Franchoo,∗1 R. Taniuchi,∗3,∗2 D. Suzuki,∗2 N. Aoi,∗4,∗2 H. Baba,∗2 F. Browne,∗2 C. M. Campbell,∗5
S. Chen,∗3,∗6 R. Crane,∗3,∗2 H. L. Crawford,∗5 H. De Witte,∗7,∗2 P. Doornenbal,∗2 C. Fransen,∗8 N. Fukuda,∗2
H. Hess,∗8,∗2 E. Ideguchi,∗4,∗2 S. Iwazaki,∗4,∗2 J. Kim,∗9 A. Kohda,∗4,∗2 T. Koike,∗10,∗2 T. Koiwai,∗11,∗2
B. Mauss,∗2 R. Mizuno,∗11,∗2 B. Moon,∗2 M. Niikura,∗11,∗2 D. Nishimura,∗12,∗2 T. Parry,∗13,∗2 M. Petri,∗3
P. Reiter,∗8 H. Sakurai,∗11,∗2 Y. Shimizu,∗2 H. Suzuki,∗2 H. Takahashi,∗12,∗2 H. Takeda,∗2 S. Thiel,∗8
K. Wimmer,∗14,∗2 Y. Yamamoto,∗4,∗2 and M. Yoshimoto∗2 for the RIBF 181 Collaboration
78

Ni is an emblematic nucleus for the study of nuclear
structure far from stability. Although it is expected tohave a doubly magic character for proton (Z = 28) andneutron (N = 50) shells, theoretical and experimental
studies around this region hint to a weakening of thismagicity, with possible shape coexistence phenomena
associated with shell quenching in proton and neutron
gaps.1) To address these questions, the RIBF181 experiment aiming at the in-beam γ-ray spectroscopy of
nuclei in the vicinity of 78 Ni was conducted at RIKEN
for 7 days in April 2021. In this report, we focus on theanalysis of the spectroscopy of 79 Cu, which contains one
proton above the core of 78 Ni.
A wide range of exotic isotopes including 80 Zn were
produced after the induced in-ﬂight ﬁssion of a primary beam of 238 U at 345 MeV/nucleon and 90-particlenA on a 4-mm-thick primary beryllium target. These
nuclei were sent through the BigRIPS separator onto
a secondary 6.8-mm-thick beryllium target, in whichknock-out reactions took place. The outgoing fragments including 79 Cu were subsequently identiﬁed in
the ZeroDegree spectrometer. The emitted γ-rays weredetected by the HiCARI germanium array2) placedaround the secondary target. To carry out event-byevent particle identiﬁcation (PID) of the beam nuclei,
we used the combination of the ToF-Bρ-∆E and twofold Bρ methods in both the BigRIPS and ZeroDegree
spectrometers to obtain the atomic number (Z) andmass-to-charge ratio (A/Q). To reduce the number ofcontaminating events, we applied conditions in correlations within diﬀerent detectors. The removed events
include the δ-electrons in the parallel-plate avalanche
counters (PPACs), the changing charge states, and thepile-up events in the plastic scintillators and ionizationchambers. The combination of these cuts reduced thetotal number of events during PID in BigRIPS by 11%.
To enhance the A/Q resolution, we applied opticalcorrections up to the third order using a multidimensional ﬁt to eliminate the dependencies of the A/Q values on the position and angular variables at diﬀerent
focal planes. This resolution improved from 0.11% to
0.08% in BigRIPS for 80 Zn isotopes and from 0.22% to0.15% in ZeroDegree for 79 Cu isotopes.
The cores and segments of the 10 available germanium clusters (4 Miniballs, 4 Clovers, P3, and Quad)were calibrated in energy with sources of 60 Co, 152 Eu,
133
Ba, and 88 Y. A preliminary Doppler correction ofthe γ-ray energy for the 80 Zn(9 Be, X)79 Cu channel wasapplied. Figure 1 shows the spectrum of the Miniballs
and Clovers. This was produced using the photogrammetry positions of the detectors and a ﬁxed velocity
at the target center. The latter was estimated using
the mean values of the measured velocity distributions
in BigRIPS and ZeroDegree and LISE++ simulations
to correct for the energy loss in the intermediate materials upstream and downstream from the target. In
this γ-spectrum, the 656 keV transition3) from the ﬁrst
(3/2− ) excited state to the (5/2− ) ground state can already be conﬁrmed. We foresee to optimize the Doppler
correction by using an event-by-event velocity and apply γ-γ coincidences to ﬁnd the remaining transitions
and reconstruct the resulting level scheme.

∗1

Laboratoire Irène Joliot Curie, Université Paris Saclay
RIKEN Nishina Center∗3 School of Physics, Electronics and Technology, University ofYork∗4 Research Center for Nuclear Physics, Osaka University∗5 Nuclear Science Division, Lawrence Berkeley National Laboratory∗6 Department of Physics, University of Hong Kong
∗7 Instituut voor Kern- en Stralingsfysica, KU Leuven∗8 Institut für Kernphysik, Universität zu Köln∗9 Department of Physics, Korea University∗10 Department of Physics, Tohoku University∗11 Department of Physics, University of Tokyo∗12 Department of Natural Sciences, Tokyo City University∗13 Department of Physics, University of Surrey∗14 IEM-CSIC∗2- 13 -

Fig. 1. Preliminary Doppler corrected γ spectrum of 79 Cu.

References
1) R. Taniuchi et al., Nature 569, 53 (2019).
2) K. Wimmer et al., RIKEN Accel. Prog. Rep. 54, S27(2021).
3) L. Olivier et al., Phys. Rev. Lett. 119, 192501 (2017).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Barrier distribution measurement of the 51 V + 159 Tb system
P. Brionnet,∗1 M. Forge,∗2,∗1 T. Fukatsu,∗3 H. Haba,∗1 D. Kaji,∗1 S. Kimura,∗1 K. Morimoto,∗1
Y. Michimoto,∗3,∗1 T. Niwase,∗4,∗1 S. Sakaguchi,∗3,∗1 H. Sakai,∗1 M. Tanaka,∗1 and Y. Yamanouchi∗3 for thenSHE Collaboration
With the discovery of elements up to oganesson (Z= 118), all reactions based on the 48 Ca beam leading to a new element have already been performed.
The next step forward to produce new element Z =119 and beyond needs to rely on 50 Ti, 51 V, or 54 Cr
beam on trans-actinium targets. However, in the super heavy mass region, the reactions using these beams
have only been studied on spherical targets (208 Pb and
209
Bi). Thus, very little information regarding the reaction parameters on deform targets is currently available with these beams. Most of the information usedby the predictions is extrapolated from the 48 Ca results. Systematic studies of reaction using these beams
on deform targets are thus needed to improve the predictive power of the diﬀerent models.
One of these important parameters is the beam energy selected for the search for new elements. The
search of the element Z = 119 is currently ongoingat RIKEN using the 51 V + 248 Cm reaction. The optimal beam energy was selected by studying the barrier distribution of this reaction.1) We decided to begin the systematic measurement of the same parameters extracted in Refs. 1) and 2) with lighter deformed
targets, starting with the 159 Tb. The relation between the maximum cross-section of production and
the QuasiElastic (QE) barrier distribution is directly
linked to the reaction dynamics.
The 51 V13+ beam was provided by the newly upgraded SRILAC accelerator.3) Similarly to the reports,1,2) we used the GARIS-III separator to transport the QE backscattering. These events correspondto the recoil of target-like events at 180◦ (or a beamlike event at 0◦ ). Using the information from our detector array located at the end of GARIS-III,3) we can use
the time-of-ﬂight telescope to select the target-like recoil nuclei. Then, by using the dose estimated throughelastic scattering of the 51 V beam onto the 159 Tb at
the target position, we can extract the barrier distribution as shown in Fig. 1 (bottom panel). The top
panel represents the reﬂection probability R(E), whichis the normalized ratio of target-like events detected
at the focal plane to the number of elastic scatterings
detected at the target position. The bottom panel represents the barrier distribution D(E) deﬁned as:

Fig. 1. Reﬂection probability (top panel) and barrier distribution (bottom panel) of the 51 V+159 Tb reaction.
The points (blue, red/orange, and green) are the measured data and the several curves CCFULL calculations4) with diﬀerent input parameters.

in the R(E) distribution. It is determined as 164.12 ±0.3 MeV (blue arrow in Fig. 1). This value is related tothe maximum of the cross-section of production in thecase of reaction on spherical targets. However, in thecase of the deformed targets, the side collision energy
is more important, as has been pointed out.1,2)
This side collision corresponds to the collision of the
projectile and target at a 90◦ angle in a compact conﬁguration. In order to extract this side collision energy,
we need to perform the Coupled Channels calculation(CCFULL4) ).
The dashed orange line in Fig. 1 represents the optimized CCFULL calculations,4) and the orange dots
represent the contribution of the side collision to theD(E) ≡ −dR/dE
The average barrier height is deﬁned at the 0.5 crossing
∗1
∗2
∗3
∗4

RIKEN Nishina Center
IPHC Strasbourg
Department of Physics, Kyushu University
Wako Nuclear Science Center (WNSC), IPNS, KEK- 14 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)

overall barrier distribution. We optimized the parameters of the CCFULL calculation to reproduce both thereﬂection probability and the barrier distribution. We
can then extract from these calculations the side collision energy as 171.5 ± 0.5 MeV (orange dot and arrow
in Fig. 1 bottom panel). These results will be compared and correlated with the precise excitation function we simultaneously measured for this reaction.5)
References
1) M. Tanaka et al., J. Phys. Soc. Jpn. 91, 084201 (2022).
2) T. Tanaka et al., Phys. Rev. Lett. 124, 052502 (2020).
3) H. Sakai et al., Eur. Phys. J. A 58, 238 (2022).
4) K. Hagino et al., Comput. Phys. Commun. 123, 143(1999).
5) P. Brionnet, in this report.

2- 15 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Excitation functions for the 51 V + 159 Tb fusion evaporation reaction
P. Brionnet,∗1 M. Forge,∗2,∗1 T. Fukatsu,∗3 H. Haba,∗1 D. Kaji,∗1 K. Morimoto,∗1 Y. Michimoto,∗3,∗1
T. Niwase,∗4,∗1 S. Sakaguchi,∗3,∗1 H. Sakai,∗1 and Y. Yamanouchi∗3,∗1 for the nSHE Collaboration
an average density of 365 ± 16 µg/cm2 and beam intensities ranging from 152 particle nA to 345 particle nA. The ER nuclei were implanted into a Doublesided Strip Silicon Detector4) that was also used forthe detection of the subsequent α-decays.
The identiﬁcation of reaction channels was only
based on the known α-decay energies and branchingratios, without any timing selection. The overall ﬁtof the α-spectrum accumulated over 24 hours at eachenergy was used to extract the individual yield of ERs
produced. Considering the transmission and detection
eﬃciency, the cross section of various exit channels was
extracted from those yields. Figure 1 shows the measured cross section of the xn, pxn, and αxn exit channels for the 51 V + 159 Tb → 210 Ra∗ reaction.

Syntheses of elements from ﬂerovium (Z = 114) tilloganesson (Z = 118) were made using the hot-fusion
reactions with 48 Ca beams on actinide targets. To
synthesize the elements beyond Z = 118, reactions
with either 50 Ti, 51 V, or 54 Cr beam on actinide targets are necessary. However, these beams have, sofar, only been used on spherical targets around 208 Pb.
Thus, any information regarding the reaction mechanisms using these beams on actinide targets will provide valuable information for the success of current andfuture searches for new elements. Unfortunately, thedirect systematic study of reaction mechanisms on actinides target is unrealistic due to the too-small fusionevaporation cross-sections (pb–fb range). Thus, theuse of a lighter surrogate system based on deformed
targets with similar deformation characteristics aroundlanthanide nuclei may give insight and valuable information regarding reaction mechanisms with 50 Ti,
51
V, or 54 Cr beams, especially regarding the side collision eﬀect.1,2) The reaction of 51 V beam on 159 Tb target presents much higher production rates (µb range)
while being an excellent surrogate reaction. Indeed,
the 159 Tb deformation parameters (β2 = 0.271, β4 =0.066) are similar to the one of the 248 Cm (β2 = 0.286,
β4 = 0.039) that is currently used in the search for the
new element Z = 119 at RIKEN.
This similarity in deformation parameters allows forthe study of the side collision eﬀect using 51 V beam on
deformed target. Has it been pointed out in Refs. 1)
and 2). this side collision eﬀect is involved in the relation between the barrier distribution and the maximum production cross-section of production for thesuper heavy elements. This relation also shows surprising diﬀerences between spherical and deformed targets
as indicated in Refs. 1) and 2). Furthermore, these
relations were derived using beams lighter than 48 Ca
and never had been directly extracted for 50 Ti, 51 V, or
54
Cr beams.
The 51 V + 159 Tb → 210 Ra∗ reaction was selected
as the ﬁrst test surrogate reaction, measuring a wide
range of excitation energies from 32 to 66 MeV. The
barrier distribution was also measured separately andreported elsewhere.3)
The GARIS-III separator was set to transport the
Evaporation Residue (ER) nuclei to the focal plane
detector array.4) The 51 V13+ beam was provided by
the newly upgraded SRILAC accelerator.4) The experiment used a rotating target of metallic 159 Tb with
∗1
∗2
∗3
∗4

RIKEN Nishina Center
IPHC Strasbourg
Department of Physics, Kyushu University
Wako Nuclear Science Center (WNSC), IPNS, KEK

Fig. 1. Excitation function of the reaction 51 V + 159 Tb:(a) αxn exit channel, (b) pxn exit channel, (c) xn exit
channel.

- 16 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)

The maximum cross-sections are the p3n with 33.1±
8.9 µb, followed by the α3n at 27.2 ± 7.3 µb and thenthe 3n at 4.4 ± 0.9 µb. The increase of the charged
particle exit channel has been observed in this lower
mass region but are not yet well reproduced by models. Discussions with the team of M. Kowal in Poland
are ongoing to reproduce this behavior and our data
based on their model.5) It also seems that the side collision eﬀect is not as present as expected for the xn
exit channel and is under discussion with K. Hagino.6)
References
1) M. Tanaka et al., J. Phys. Soc. Jpn. 91, 084201 (2022).
2) T. Tanaka et al., Phys. Rev. Lett. 124, 052502 (2020).
3) P. Brionnet et al., in this report.
4) H. Sakai et al., Eur. Phys. J. A 58, 238 (2022).
5) T. Cap et al., Eur. Phys. J. A 58, 231 (2022).
6) K. Hagino et al., Comput. Phys. Commun. 123, 143(1999).

2- 17 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Analysis of proton elastic scattering from 132 Sn and 48 Ca at
300 MeV/nucleon in inverse kinematics∗1

Department of Physics, Toho University
RIKEN Nishina Center∗3 Department of Physics, Kyoto University∗4 Cyclotron and Radioisotope Center, Tohoku University∗5 School of Physics, Beihang University∗6 Research Center for Nuclear Physics, Osaka University∗7 Center for Nuclear Study, University of Tokyo∗8 Department of Physics, Tohoku University∗9 Department of Physics, Osaka University∗10 Department of Applied Physics, Miyazaki University∗11 Department of Natural Sciences, Tokyo City University
∗2

45
40
35
30
25
20
15
10
5
0
60

65

70

75

80

85

90

recoil angle [degrees]Fig. 1. Angular distribution spectrum for selected elastic
scattering events using NaI(TI) calorimeters.

Counts / 0.5[MeV]In this report, we show progress of analysis of proton elastic scattering from 132 Sn at 300 MeV/nucleon
in inverse kinematics. Previously, we already reported
the experimental conditions. We also showed the analyses of the particle identiﬁcations of the RI beams, andthe excitation energy spectra, and the angular distribution of the elastic scattering yields of 132 Sn.1,2) We
have discussed particle identiﬁcation for beam particles,
the excitation energy and of the angular distributionof 132 Sn.1–3) In order to obtain the absolute value ofelastic scattering cross-section of 132 Sn, it is necessary
to determine the target thickness. As calibration data
to determine it, it was necessary to analyze 48 Ca dataobtained in the same environment as the 132 Sn measurement. 48 Ca is a stable nucleus and, like 132 Sn, adouble magic number nucleus. The elastic scattering
diﬀerential cross section of 48 Ca has already been measured with high accuracy at RCNP. We assume thatthe target thickness can be determined by comparing
the cross-section obtained in the analysis with the data
already obtained at RCNP. Herein, we report on theanalysis of 48 Ca. We performed measurement of proton elastic scattering from 48 Ca in inverse kinematics at
300 MeV/nucleon at F12 area. The total beam rate wasup to 300 kcps, and purity of 48 Ca was 15%. By using
missing mass spectroscopy, the excitation energy distribution of 48 Ca was deduced from the measured recoil
proton kinetic energy and scattering angle information.
We identiﬁed elastic events of 48 Ca as shown in Fig. 2.
Figure 2 shows the excitation energy spectrum of the
proton scattering from 48 Ca in the recoil angle 77◦ –80◦ .
The excitation energy resolution (in r.m.s.) of 900 keV
was achieved at a scattering angle of 77–80 degrees. Although the resolution is 1.5 times worse than that for
132
Sn, we could separate the excited state and the elastic scattering as shown in Fig. 2. The main excited stateenergy are 3.8 MeV (Jπ ) or 4.5 MeV (Jπ ). We will deduce the elastic scattering diﬀerential cross section ofCounts / 0.5[degrees]

T. Harada,∗1,∗2 J. Zenihiro,∗3,∗2 Y. Matsuda,∗4,∗2 S. Terashima,∗5 H. Sakaguchi,∗6 N. Aoi,∗6,∗2 H. Baba,∗2
M. Dozono,∗7,∗2 F. Endo,∗8,∗2 S. Enyo,∗3 Y. Fujikawa,∗3 S. Hanai,∗7 S. Hayakawa,∗7 Y. Hijikata,∗3,∗2
J. W. Hwang,∗7 N. Imai,∗7 K. Inaba,∗3 S. Ishida,∗4 T. Isobe,∗2 T. Kawabata,∗9,∗2 S. Kiyotake,∗10 A. Kohda,∗6,∗2
H. Kurosawa,∗4 R. Kojima,∗7 R. Maeda,∗4 Y. Maeda,∗10 S. Y. Matsumoto,∗3 R. Matsumura,∗1,∗2 B. Mauss,∗2
S. Michimasa,∗7 T. Murakami,∗3,∗2 D. Nishimura,∗11,∗2 T. Nishimura,∗10 K. Nosaka,∗4 S. Ota,∗7 K. Sakanashi,∗3
H. Shimizu,∗7 D. Suzuki,∗2 J. Tanaka,∗2 R. Tsunoda,∗7 T. Uesaka,∗2 and K. Yamamoto∗450

40

σ : ~ 900keV

30

20

10

0
−10

−5

0

5

10

15

20

25

30
Ex [MeV]Fig. 2. Excitation energy spectrum of 48 Ca at recoil angles
in the range of 77◦ –80◦ .
48

Ca by selecting elastic scattering from information on
the excitation energy distribution. We plan to determine
the target thickness by comparing the diﬀerential crosssection obtained by analysis data and the data alreadyobtained at RCNP. Using the determined target thickness, we plan to determine the diﬀerential cross sectionof 132 Sn for the ﬁrst time in the world.

References
1) J. Zenihiro et al., RIKEN Accel. Prog. Rep. 53, 44 (2019).
2) T. Harada et al., RIKEN Accel. Prog. Rep. 54, 18 (2020).
3) T. Harada et al., RIKEN Accel. Prog. Rep. 55, 23 (2021).
- 18 -

Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

The result of electron scattering with Xe isotopes
at SCRIT electron scattering facility
H. Wauke,∗1 D. Abe,∗1 Y. Abe,∗2 A. Enokizono,∗2 R. Danjo,∗1 T. Goke,∗1 Y. Honda,∗1,∗2 Y. Ishikura,∗1
Y. Itou,∗3 K. Kurita,∗4 H. Ohnishi,∗2 C. Legris,∗1 Y. Maehara,∗3 Y. Nagano,∗5 R. Obara,∗1 R. Ogawara,∗3
T. Suda,∗1,∗2 K. Tsukada,∗2,∗3 M. Watanabe,∗2 M. Wakasugi,∗2,∗3 and S. Yoshida∗3
Self-Conﬁning Radioactive Ion Target (SCRIT) electron scattering facility1) was constructed to perform
electron scattering experiments for short-lived unstable nuclei. SCRIT is a unique technique to achieve aluminosity of 1027 cm−2 s−1 via the trapping of a few
target ion that is, 108 particles/pulse, along the electronbeam.
We have started a series of measurements of isotope(Z = 50) and isotone (N = 82) dependence of nuclear charge density distribution. These studies use thenuclei of Xe isotopes (138, 136, 134, 132, 130, 128, 126, 124 Xe)
and N = 82 isotones (138 Ba,2) 137 Cs,3) 136 Xe, 132 Sn)
including the 132 Sn and 137 Cs, unstable nuclei. The
Xe isotope has the second most stable nuclei after Sn;
however, no electron scattering data is available, except
for 132 Xe,4) which was measured at the SCRIT facility.
These isotope and isotone dependencies should provide
invaluable information for theoretical development.5,6)
In 2022 July, we conducted the electron scattering experiment using 136, 134, 132, 130 Xe targets. The Xe target
was ionized with FEBIAD-type ion source by injecting
natural Xe gas directly into the ionization chamber inside the ERIS.7) The ionized Xe was mass-separated bya bending magnet installed after ERIS. After coolingand stacking inside the FRAC,8) almost 108 of massspeciﬁc Xe ions/pules were transported to the SCRIT
system at a frequency of 1 Hz. Experiments with 136 Xe
were performed at both 150 and 250 MeV, whereas theexperiments with 134, 132, 130 Xe were only performed at
150 MeV. Further, the beam current was 250 mA at
the beginning of the data acquisition and reduced to
150 mA at the end. Figure 1 shows the yield distributions of 136 Xe with momentum transfer following acceptance corrections. The solid lines represent the calculated ones using the theoretical charge density distribution of 136 Xe5) using the phase shift calculation code
DREPHA.9) The total experimental time and averageluminosity of each experiment is presented in Table 1.
Average luminosities were measured by a luminosity
monitor.
The 124 Xe, which is scheduled to be launched soon,
has a smaller abundance ratio than other Xe, thus, wehave upgraded ERIS and have already achieved a production rate similar to that of 136 Xe. From 2023, we
∗1
∗2
∗3
∗4
∗5

Research Center for Electron Photon Science, Tohoku University
RIKEN Nishina Center
Institute for Chemical Research, Kyoto University
Department of Physics, Rikkyo University
Faculty of Science, Yamagata University- 19 -

Fig. 1. Yield distributions of 136 Xe with momentum transfer following acceptance corrections. Filled and opened
circles indicate preliminary results from this study. The
solid lines are the phase-shift calculated values obtainedusing a theoretically calculated charge-density distribution of 136 Xe.5)

Table 1. Experimental situation.

Nuclei

136

Xe
Xe
134
Xe
132
Xe
130
Xe
total
136

Beam
Energy[MeV]

Total Exp.
time [s]Lumi. ave[× 1027cm−2 s−1 ]

150
250
150
150
150

1.94×105
4.28×105
1.18×105
0.90×105
1.29×105
9.59×105

1.55
2.08
1.66
1.69
1.33

will conduct experiments on the remaining Xe and proceed with further analysis.
References
1) M. Wakasugi et al., Phys. Rev. Lett. 100, 164801 (2008).
2) K. Tsukada et al., RIKEN Accel. Prog. Rep. 55, 24(2021).
3) K. Tsukada et al., Phy. Rev. Lett. 131, 092502 (2023)
4) K. Tsukada et al., Phys. Rev. Lett. 118, 262501 (2017).
5) T. Liang et al., Phys. Rev. C 98, 044310 (2018).
6) X. Roca-Maza et al., Phys. Rev. C 87, 014304 (2013).
7) T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B
317, 357 (2013).
8) M. Wakasugi et al., Rev. Sci. Instrum. 89, 095107 (2018).
9) B. Drepher, A phase-shift calculation code for elastic electron scattering (private communication with
J. Friedrich).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Beta-delayed proton emission in the decay of 71 Kr
A. Vitéz-Sveiczer,∗1,∗2,∗3 A. Algora,∗1,∗2 G. Kiss,∗2,∗4 B. Rubio,∗1 A. Morales,∗1 P. Sarriguren,∗5 P. Van Isacker,∗6
G. de Angelis,∗7 F. Recchia,∗8,∗9 S. Nishimura,∗4 J. Agramunt,∗1 V. Guadilla,∗1 A. Montaner-Pizá,∗1 S. Orrigo,∗1
Á. Horváth,∗10 D. Napoli,∗7 S. Lenzi,∗8,∗9 A. Boso,∗8,∗9 V. Phong,∗4,∗11 J. Wu,∗4 P. Söderström,∗4
T. Sumikama,∗4 H. Suzuki,∗4 H. Takeda,∗4 D. Ahn,∗4 H. Baba,∗4 P. Doornebal,∗4 N. Fukuda,∗4 N. Inabe,∗4
T. Isobe,∗4 T. Kubo,∗4 S. Kubono,∗4 H. Sakurai,∗4 Y. Shimizu,∗4 C. Sidong,∗4 B. Blank,∗12 P. Ascher,∗12
M. Gerbaux,∗12 T. Goigoux,∗12 J. Giovinazzo,∗12 S. Grévy,∗12 T. Kurtukián Nieto,∗12 C. Magron,∗12
W. Gelletly,1,∗13 Z. Dombrádi,∗2 Y. Fujita,∗14,∗15 M. Tanaka,∗15,∗4 P. Aguilera,∗16 F. Molina,∗16 J. Eberth,∗17
F. Diel,∗17 D. Lubos,∗18 C. Borcea,∗19 E. Ganioglu,∗20 D. Nishimura,∗21 H. Oikawa,∗22 Y. Takei,∗22 S. Yagi,∗22
W. Korten,∗23 G. de France,∗6 P. Davies,∗24 J. Liu,∗25 J. Lee,∗25 T. Lokotko,∗25 I. Kojouharov,∗26 N. Kurz,∗26
H. Shaﬀner,∗26 and A. Petrovici∗19
We present preliminary results of our study of βdelayed proton emission detected in the β-decay of71
Kr. These results were obtained in the frameworkof the experiment NP1112-RIBF93. In our experimenta 40 particle nA 78 Kr primary beam provided by RI
Beam Factory (RIBF) impinged on a 5-mm thick Be
target to produce 9.8 million 71 Kr implants—after optimization to separate 71 Kr secondary beams—in the
WAS3ABi active stopper.1) The WAS3ABi detector
was surrounded by the EURICA γ-ray spectrometer.2)
Beta-delayed protons were distinguished from βparticles in the same way as in our earlier work on 70 Kr,
using an energy threshold of 1400 keV measured in
WAS3ABi,3) resulting in the deposited energy spectrum
shown in Fig. 1. The number of protons was divided
by the number of implants in order to calculate the βdelayed proton emission probability εp = 2.49(10)% inagreement with the value of εlit
p = 3.1(4)% found in
the literature.4) In our analysis the dead time of thedetector system was also accounted for, while a 100%detection eﬃciency was assumed for single protons.
A half-life value of T1/2 = 94.1(4) ms was derived

Fig. 1. Intensity distribution as a function of the depositedenergy of the β-delayed proton events in the DSSSD.
The high energy tail of β-particles was extrapolated by
an exponential function, shown in grey.

from the time correlations between protons and implants using an exponential ﬁt shown in Fig. 2, in agreement with the results obtained from implant-β timecorrelations (T1/2 = 94.5(2) ms) and from the decay
curve of β-delayed γ-transitions in the daughter nucleus(T1/2 = 95.5(24) ms).

∗1

Instituto de Fisica Corpuscular
Institute for Nuclear Research (Atomki)∗3 PhD School of Physics, University of Debrecen∗4 RIKEN Nishina Center∗5 Instituto de Estructura de la Materia∗6 Grand Accélérateur National d’Ions Lourds∗7 INFN, Laboratori Nazionali di Legnaro∗8 INFN, Sezione di Padova∗9 Dipartimento di Fisica dell Universitá degli Studi di Padova∗10 Department of Physics, Eötvös Loránd University∗11 Faculty of Physics, VNU Hanoi University of Science∗12 Centre d Etudes Nucléaires de Bordeaux-Gradignan∗13 Department of Physics, University of Surrey∗14 Research Center for Nuclear Physics, Osaka University∗15 Department of Physics, Osaka University∗16 Comisión Chilena de Energı́a Nuclear∗17 Institute of Nuclear Physics, University of Cologne∗18 Physik Department E12, Technische Universität München∗19 National Institute for Physics, Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering∗20 Department of Physics, Istanbul University∗21 Department of Natural Sciences, Tokyo City University∗22 Department of Physics, Tokyo University of Science∗23 CEA Saclay, IRFU, Gif-sur-Yvette∗24 Department of Physics, University of York
∗25 Department of Physics, University of Hong Kong
∗26 GSI Helmholtzzentrum für Schwerionenforschung GmbH∗2

- 20 -

Fig. 2. Time correlations between β-delayed proton eventsand 71 Kr implants. The total ﬁt represents an exponential function plus a linear background.

The theoretical interpretation of the experimental
data is ongoing.
References
1) S. Nishimura, Prog. Theor. Exp. Phys. 2012, 03C006 (2012).
2) P. -A. Söderström et al., Nucl. Instrum. Methods Phys. Res.
B 317, 649 (2013).
3) A. Vitéz-Sveiczer et al., Phys. Lett. B 830, 137123 (2022).
4) S. Waniganeththi et al., Phys. Rev. C 106, 044317 (2022).

Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Isomeric state studies using the DTAS detector
J. A. Victoria,∗1 V. Vegas,∗1 A. Algora,∗1,∗2 B. Rubio,∗1 J. L. Tain,∗1 A. Tolosa,∗1 J. Agramunt,∗1 E. Nacher,∗1
S. E. A. Orrigo,∗1 V. Guadilla,∗3 G. Kiss,∗2 D. Sohler,∗2 I. Kuti,∗2 T. Davinson,∗4 O. B. Hall,∗4 D. M. Kahl,∗4
C. G. Bruno,∗4 C. J. Appleton,∗4 P. J. Woods,∗4 S. Nishimura,∗5 N. Fukuda,∗5 H. Suzuki,∗5 D. S. Ahn,∗5
H. Baba,∗5 Y. Shimizu,∗5 H. Takeda,∗5 D. Nishimura,∗5 T. Isobe,∗5 M. Kaneko,∗5 S. Kubono,∗5 H. Sakurai,∗5
H. Shimizu,∗5 T. Sumikama,∗5 P. Doornenbal,∗5 M. L. Cortes,∗6 Zs. Podolyak,∗7 W. Gelletly,∗7 E. Ganioglu,∗8
Y. Fujita,∗9 F. Molina,∗10 J. Liu,∗11 J. Lee,∗11 K. P. Rykaczewski,∗12 M. Wolinska-Cichocka,∗13 M. Labiche,∗14
C. J. Griﬃn,∗15 S. Bae,∗16 J. Ha,∗16 and Y. Litvinov∗17
In this contribution we present preliminary work
aimed to assess the capabilities of the DTAS detector
to study isomeric states. They are of particular interest, since they can provide information about nuclear
structure. They are also relevant in the analysis of total
absorption data, since they may break the continuityof emitted gamma-ray cascades from high lying states
populated in beta decay. This contribution is related
to experiment NP1612-RIBF147,1) which focuses on the
study of the beta decay of 100 Sn and neighbouring nuclei using the DTAS modular total absorption spectrometer2) and the AIDA implantation detector.
In the study, we developed analysis tools to look fornuclei with unknown isomeric states in the vicinity of100
Sn using DTAS in combination with the in-ﬂight radioactive ion beam separator BigRIPS. This setup allows
one to study the gamma rays of a particular isomeric decay, looking for time correlations between ions identiﬁed
in BigRIPS and the associated gamma cascade detected
in DTAS, taking advantage of its high eﬃciency. In our
analysis two dimensional spectra were generated wherein one axis we have the time diﬀerence between the timeof correlated gamma events detected in DTAS modules
and the ion implantation time provided by BigRIPS andon the other axis we have the energy detected by the
DTAS individual modules. Isomeric states should beseen in this ﬁgure as gamma transitions (or levels) vanishing as time diﬀerences increase. The very high eﬃciency of the DTAS detector to gamma cascades can be
an asset in this context.
To test the viability of the procedure we have studied
the 98 Cd case, which has a high production rate in our
experiment and has well known isomeric states. The

Fig. 1. Top: 2D ﬁgure corresponding to a 98 Cd gamma cascade detected in DTAS and its energy projection. Bottom: Fit of the the time projection of a gate around the∼1400 keV energy peak marked in the upper panel.

gamma cascade data obtained with the DTAS detector from the de-excitation of 98 Cd isomeric decay populated in the fragmentation reaction can be comparedwith data obtained previously from high resolution experiments using germanium detectors.3)
The comparison between the half-lives from the literature3,4) and the results from our preliminary analysis
shows the validity of the method. In the analysis of thelower states, feeding from above is taking into account.

∗1

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

- 21 -

Level
12+
8+
6+

Literature3,4)224(5) ns
154(16) ns
13(2) ns

Present Work
216(7) ns
150(3) ns
11(1) ns

In the next step we plan to systematically look forisomers produced in our experiment.
References
1) A. Algora et al., RIKEN Accel. Prog. Rep. 53, 30 (2019).
2) J. L. Tain et al., Nucl. Instrum. Methods Phys. Res. A
803, 36 (2015).
3) J. Park et al., Phys. Rev. C 96, 044311 (2017).
4) J. Chen et al., Nucl. Data Sheets 164, 1 (2020).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Progress on the analysis of Pn -values relevant for the formation of
the r-process rare-earth peak
M. Pallàs,∗1 A. Tarifeño-Saldivia,∗2,∗1 G. G. Kiss,∗3 J. L. Tain,∗2 A. Tolosa-Delgado,∗4,∗2 A. Vitéz-Sveiczer,∗3,∗5
F. Calviño,∗1 J. Agramunt,∗2 A. Algora,∗2 N. T. Brewer,∗8,∗6 R. Caballero-Folch,∗9 T. Davinson,∗10
I. Dillmann,∗9,∗11 A. Estrade,∗12 N. Fukuda,∗7 R. K. Grzywacz,∗8,∗6 O. Hall,∗10 N. Mont-Geli,∗1 A. I. Morales,∗2
A. Navarro,∗1 N. Nepal,∗7 S. Nishimura,∗7 B. C. Rasco,∗8,∗6 K. P. Rykaczewski,∗6 T. N. Szegedi,∗3 V. Phong,∗7
R. Yokoyama,∗13 M. Wolińska-Cichocka,∗14 and P. J. Woods∗10 for the BRIKEN Collaboration∗15
Rapid neutron capture (the r-process) producesnearly half of the nuclei heavier than iron in explosive
stellar scenarios. Above the mass number A = 100,
there are two main peaks in the r-process solar-systemabundances, are located at A ∼ 130 and A ∼ 195.
Located between them, the Rare-Earth Peak (REP)
is a tiny but deﬁnite peak at mass number A ∼ 160
that results from the freeze-out during the last stagesof neutron exposure. According to theoretical models
and sensitivity studies, half-lives (T1/2 ) and β-delayed
neutron emission probabilities (Pxn ) of neutron-richnucleus, in the mass region A ∼ 160 for 55 ≤ Z ≤ 64
are critical for the formation of the REP.1,2) As a partof the BRIKEN collaboration, the NP1612-RIBF148
experiment measured half-lives and β-delayed from Ba
to Gd (Z = 56–64). In 2018, an experimental run centered on 165 Pm was conducted using a total of 5 daysof beamtime. The results for Pm to Gd (Z = 61–64)
species are already published.3) The data analysis for
Ba to Nd (Z = 56–60) species using the method proposed in4) is presented in this report.
The NP1612-RIBF148 experimental setup consisted of the Advanced Implantation Detector Array(AIDA)5) and the BRIKEN neutron counter.6) The
neutron counter was placed surrounding AIDA to detect the β-delayed neutrons oﬀering a nominal value
for the eﬃciency of 68.6% up to 1 MeV.
In Fig. 1, the preliminary results for the P1n values are compared with evaluated nuclear data fromthe ENSDF and some theoretical predictions.7–9) Preliminary reports include 14 new P1n values (151–152 Ba,

Fig. 1. Preliminary P1n values derived in this work (reddot) compared with previous measurements (blue triangle) and theoretical calculations.7–9)

151–153

La, 154–156 Ce, 155–158 Pr, and 159–160 Nd). Twoother P1n values (149–150 La) were also remeasured, obtaining consistent results with previous measurements.
Our data supports the overall trend for all P1n predictions when compared to theoretical models. The
pn-RQRPA + HFM model9) best replicates the experimental data and provides good agreement for the
majority of the isotopes.
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) G. G. Kiss et al., Astrophys. J. 936, 107 (2022).
4) C. J. Griﬃn et al., Jap. Phys. Soc. Conf. Proc. 14,020622 (2017).
5) A. Tarifeño-Saldivia et al., J. Instrum. 12, P04006(2017).
6) A. Tolosa-Delgado et al., Nucl. Instrum. Methods Phys.
Res. A 925, 133 (2019).
7) P. Möller et al., At. Data Nucl. Data Tables 125, 1(2019).
8) T. Marketin et al., Phys. Rev. C 93, 025805 (2016).
9) F. Minato et al., Phys. Rev. C 104, 044321 (2021).

∗1

Institut de Tècniques Energètiques (INTE), Universitat
Politècnica de Catalunya (UPC)∗2 Instituto de Fı́sica Corpuscular (IFIC), CSIC-UV∗3 Institute for Nuclear Research (ATOMKI)∗4 Department of Physics, University of Jyväskylä
∗5 Doctoral School of Physics, University of Debrecen∗6 Physics Division, Oak Ridge National Laboratory∗7 RIKEN Nishina Center∗8 Department of Physics and Astronomy, University of Tennessee∗9 TRIUMF, Vancouver∗10 School of Physics and Astronomy, University of Edinburgh∗11 Department of Physics and Astronomy, University of Victoria∗12 Department of Physics and Science of Advanced Materials
Program, Central Michigan University∗13 Center for Nuclear Study, University of Tokyo∗14 Heavy Ion Laboratory, University of Warsaw∗15 www.wiki.ed.ac.uk/display/BRIKEN/Home- 22 -

Ⅱ-1. Nuclear Physics
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Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

The study of the core-excited component in 11 Li
Y. Li,∗1,∗2 Z. Yang,∗3 Y. Kubota,∗1 and T. Uesaka∗1 for the SAMURAI18 Collaboration
11

Li is one of the most well-known drip-line nuclei innuclear physics. The discovery of a spatially extended
structure of neutrons in 11 Li, which is now widely known
as “halo” structure, opened the very active ﬁeld of research with unstable nuclear beams.1) 11 Li has the Borromean nature, generally considered as a 3-body systemof 9 Li plus 2 well-decoupled valence neutrons. However,recent theoretical studies pointed out that contributionof the excited 9 Li core could also be signiﬁcant2,3) in the
ground state of 11 Li. But no experiment has hitherto
succeeded in providing a direct information about theexcited-core in 11 Li.
The SAMURAI18 experiment performed at the Radioactive Isotope Beam Factory (RIBF) in RIKEN employed the quasi-free (p, pn) reaction. Kubota et al.4) reported the dineutron correlation localized radially on the11
Li surface with the data of the 11 Li(p, pn)9 Li(g.s) + nchannel. The core-excited component associated withbound excited states of 9 Li (J π = 1/2− , Ex = 2.69 MeV)
was also studied from coincident gamma-ray measurement and no signiﬁcant contribution of this component
was observed, which can be attributed to the spin-parity
constraints.5) Thus, it can be expected that the coreexcited component in 11 Li that we are interested inshould be associated with a 9 Li excited state with J π= 3/2− and with a higher excitation energy above the8
Li + n breakup threshold. By looking into the 8 Li + 2nchannel of the SAMURAI18 experiment, we will be able
to probe the 9 Li*(unbound) + n component in 11 Li.
Secondary 11 Li beams (∼ 1 × 105 pps, ∼246 MeV/
nucleon) were produced from the fragmentation of 48 Ca
beam at 345 MeV/nucleon and selected by the BigRIPS
fragment separator. They were then tracked onto the
150-mm-thick MINOS target using two multiwire drift
chambers. After a (p, pn) reaction, the target protonand one of the neutron of 11 Li were scattered to large
polar angles. The recoil particle detector (RPD) wascomposed of a multiwire drift chamber and a plastic scintillator hodoscope. The neutron detector array WINDS
was installed to measure the scattering angle and thetime of ﬂight of the knockout neutron. The beam-like
residues—the charged fragment 8 Li and two neutrons—
were analyzed by the SAMURAI spectrometer and theneutron detector array NEBULA, respectively. Single
incoming neutron could induce signals in multiple detectors of NEBULA, a phenomenon commonly called crosstalk. The time-space-separation cuts and the causality
cuts of velocity were applied to eliminate these fake twoneutron events.6)
The relative energy spectrum of 10 Li is reconstructedfrom coincident 8 Li + n + n events using the invariant∗1∗2∗3

Spin isospin Laboratory, RIKEN
Institute of Modern Physics, Chinese Academy of Sciences
School of Physics, Peking University- 23 -

mass method and is presented in Fig. 1. Two resonancelike structures are observed at Erel ∼ 0.3 MeV and at
Erel ∼ 1.6 MeV. The spectrum can be well ﬁtted using
a sum of an Is-wave virtual state for the ﬁrst peak anda p-wave resonance for the second peak. Figure 2 shows
the Dalitz plot of the relative energy of the subsystem
8
Li + n (Efn ) versus that of 8 Li + n + n (Erel ). The correlation pattern in the Erel range of 1.3–1.7 MeV is consistent with the sequential two-neutron emission via anintermediate 9 Li resonant state with Efn ∼ 0.3 MeV, andFig. 1. Relative energy spectrum for 8 Li + 2n. The blue
dashed line, red dashed line and the green line represent
the the s-wave virtual state ﬁt, p-wave resonance ﬁt andsum of these two components, respectively.

Fig. 2. Dalitz plot of the relative energy. The horizontal
axis represents the relative energy of 8 Li + n + n (Erel )and vertical axis represents the relative energy of 8 Li +n (Efn ).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)

this component should thus be assigned to the excitedcore conﬁguration in the ground state of 11 Li. For the
next step, we will analyze the momentum distributionof the knockout neutron to determine its single-particle
orbital occupation. By combining with the theoretical
calculation that is now in progress we will be able to pin
down the excited-core component in 11 Li.
References
1) I. Tanihata et al., Phys. Rev. Lett. 55, 2676 (1985).
2) G. Potel et al., Phys. Rev. Lett. 105, 172502 (2010).
3) Y. Kikuchi et al., Phys. Rev. C 87, 034606 (2013).
4) Y. Kubota et al., Phys. Rev. Lett. 125, 252501 (2020).
5) Y. Kubota, Ph.D Thesis, University of Tokyo (2016).
6) Y. Kondo et al., Nucl. Instrum. Methods Phys. Res. B
463, 173 (2020).

- 24 -

2

Ⅱ-1. Nuclear Physics
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Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Observation of 9 Li + d decay channel in 11 Li(p, n) reaction
L. Stuhl,∗1,∗2,∗3 M. Sasano,∗3 J. Gao,∗3,∗4 Y. Hirai,∗5 K. Yako,∗2 T. Wakasa,∗5 D. S. Ahn,∗3 H. Baba,∗3
A. I. Chilug,∗6,∗3 S. Franchoo,∗7 Y. Fujino,∗8 J. Gibelin,∗9 I. S. Hahn,∗1,∗10 Z. Halász,∗11 T. Harada,∗12,∗3
M. N. Harakeh,∗13,∗14 D. Inomoto,∗5 T. Isobe,∗3 H. Kasahara,∗5 D. Kim,∗1,∗15 G. G. Kiss,∗11 T. Kobayashi,∗16,∗3
Y. Kondo,∗17,∗3 Z. Korkulu,∗1,∗3 S. Koyama,∗18,∗3 Y. Kubota,∗3 A. Kurihara,∗17 H. N. Liu,∗19 M. Matsumoto,∗17
S. Michimasa,∗2 H. Miki,∗17,∗3 M. Miwa,∗20 T. Motobayashi,∗3 T. Nakamura,∗17,∗3 M. Nishimura,∗3 H. Otsu,∗3
V. Panin,∗3 S. Park,∗10 A. T. Saito,∗17,∗3 H. Sakai,∗3 H. Sato,∗3 T. Shimada,∗17 Y. Shimizu,∗3 S. Shimoura,∗2
A. Spiridon,∗6 I. C. Stefanescu,∗6 X. Sun,∗3,∗4 Y. L. Sun,∗19 H. Suzuki,∗3 E. Takada,∗21 Y. Togano,∗8,∗3
T. Tomai,∗17,∗3 L. Trache,∗6 D. Tudor,∗6,∗3 T. Uesaka,∗3 H. Yamada,∗17 M. Yasuda,∗17 K. Yoneda,∗3
K. Yoshida,∗3 J. Zenihiro,∗3 and N. Zhang∗22,∗2
observation of these diﬀerent decay channels was conﬁrmed. Among them, the most interesting decay modeis 9 Li + d. This channel is related to the possibility thatin halo nuclei, the core and halo particles could decay,
more or less independently, into diﬀerent channels.9)
We observed a strong transition at approximately
19 MeV in the excitation energy spectrum of 11 Be. The
angular distribution in center-of-mass angle of the observed state indicates a strong forward peaking nature,
which suggests the GT transition, as depicted in Fig. 1,
in agreement with previous β-decay studies.
CM (deg.)In the SAMURAI30 experiment, we studied theGamow-Teller (GT) giant resonance in the drip-line nucleus 11 Li at 181 MeV/nucleon utilizing the missingmass technique.1) The 11 Li nucleus is the showcase of a
two-neutron halo system, with its very extended matter distribution related to the small energy necessary to
remove the neutrons. The charge-exchange (p, n) reactions in inverse kinematics are eﬃcient tools to extract
the B(GT) strengths of unstable isotopes up to highexcitation energies without the Q-value limitation.2) In
our previous study, we demonstrated that accurate information about isovector spin-ﬂip giant resonances canbe obtained for unstable nuclei using this probe.3) The
setup of the PANDORA low-energy neutron time-ofﬂight counter4) and SAMURAI magnetic spectrometer5) as well as a thick liquid hydrogen target, facilitate
the performance of measurements with high luminosity.
The β decay of 11 Li is complex. The large massdiﬀerence between 11 Li and its daughter 11 Be (Q =20.6 MeV) implies that several decay channels to thebound and unbound states in 11 Be are open. In thelatter cases, the daughter breaks into fragments, andthe emission of one, two, and three neutrons, α particles and 6 He, tritons, and deuterons has been observedin several β-decay studies.6,7) In our previous reports8)
on the preliminary results on GT giant resonance, theEx (11Be) (MeV)∗1

Center for Exotic Nuclear Studies, Institute for Basic Science∗2 Center for Nuclear Study, University of Tokyo∗3 RIKEN Nishina Center∗4 School of Physics, Peking University∗5 Department of Physics, Kyushu University∗6 Horia Hulubei National Institute for R&D in Physics andNuclear Engineering∗7 Institute de Physique Nucléaire, University Paris-Saclay∗8 Department of Physics, Rikkyo University∗9 Nuclear Physics Labratory LPC CAEN
∗10 Department of Physics, Ewha Womans University∗11 Institute for Nuclear Research (ATOMKI)∗12 Department of Physics, Toho University∗13 Department of Physics, University of Groningen∗14 GSI Helmholtzzentrum für Schwerionenforschung∗15 Department of Physics, Korea University∗16 Department of Physics, Tohoku University∗17 Department of Physics, Tokyo Institute of Technology∗18 Department of Physics, University of Tokyo∗19 Départment Physique Nucl., CEA, University Paris-Saclay∗20 Department of Physics, Saitama University∗21 National Institute of Radiological Sciences (NIRS)∗22 Institute of Modern Physics, Chinese Academy of Sciences- 25 -

Fig. 1. Angular distribution, in the 0◦ –25◦ center-of-massangular range, of the strong peak observed in the excitation energy spectrum of the daughter nucleus 11 Be forthe 9 Li + d decay mode.

References
1) M. Sasano et al., Phys. Rev. Lett. 107, 202501 (2011).
2) T. N. Taddeucci et al., Nucl. Phys. A 469, 125 (1987).
3) J. Yasuda et al., Phys. Rev. Lett. 121, 132501 (2018).
4) L. Stuhl et al., Nucl. Instrum. Methods Phys. Res. A
866, 164 (2017).
5) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
6) R. Raabe et al., Phys. Rev. Lett. 101, 212501 (2008).
7) I. Mukha et al., Nucl. Phys. A 616, 201 (1997).
8) L. Stuhl et al., RIKEN Accel. Prog. Rep. 53, 38 (2019).
9) T. Nilsson et al., Hyperﬁne Interact. 129, 67 (2000).

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

SAMURAI18: comprehensive study of 11 Li
Y. Kubota,∗1,∗2 A. Corsi,∗3 Z. H. Yang,∗4 P. André,∗3 Y. Li,∗2,∗5 M. Miwa,∗6 Y. L. Sun,∗7 and T. Uesaka∗1,∗2
for the SAMURAI18 Collaboration
Since the discovery of the neutron halo, 11 Li has been
one of the most attractive neutron drip-line nuclei. It
is known as a Borromean nucleus, described as a threebody system with two weakly bound valance neutrons
around a 9 Li core nucleus, with none of the two-bodysubsystems (10 Li or 2 n) having bound states. A hypothetical bound state of two neutrons, known as the
dineutron,1) is thought to be closely related to its existence.
The quasi-free knockout reaction in inverse kinematics was employed in this study to reveal the two-neutron
correlation in 11 Li without breaking quantum coherence.2) By introducing the liquid hydrogen target system MINOS3) to the RIKEN RIBF, an unprecedentedly high luminosity has been realized. The dedicated(p, pn) setup combined with the SAMURAI spectrometer4) allowed kinematically “too” complete measurement resulting in high reliability.
By knocking out a valence neutron, the unbound 10 Li
was produced, and the decay channel of 9 Li + n wasinvestigated. The known low-lying structures of s-wave
virtual state and p-wave resonances were identiﬁed, andthe resonance parameters were signiﬁcantly improved.
Furthermore, an exceptionally narrow resonance witha width of 0.7 MeV at a relative energy of 5.5 MeV
was newly found and identiﬁed as a d-wave resonanceby the multipole decomposition analysis. Recently, theanalysis of the decay channel of 8 Li + 2n has revealed
an interesting structure that provides insight into the9
Li core excitation in the ground state of the 11 Li.5)
The in-nucleus momentum k of the knockout neutronis reconstructed from the measured momentum of therecoil proton and the knockout neutron. This value isused as a measure of the radial position of the dineutron as well as to deﬁne the correlation angle θnf , whichis the measure of the dineutron strength. The relationship between θnf and k reveals that the dineutron is
localized at the surface of 11 Li and changes its shape inother region, such as near the center of the nucleus andin the tail of the halo.6) The same analysis has been
carried out for 14 Be and 17 B, and the universality ofthe dineutron is becoming apparent.7)
Only dineutron in the ground state can be studied
with one neutron knockout. In order to overcome thislimitation, the proton knockout from 12 Be was used
∗1
∗2
∗3
∗4
∗5
∗6
∗7

RIKEN Cluster for Pioneering Research
RIKEN Nishina CenterDépartement de Physique Nucléaire, IRFU, CEA, Université
Paris-Saclay
Department of Physics, Peking University
Institute of Modern Physics, Chinese Academy of Sciences
Department of Physics, Saitama University
Institut für Kernphysik, Technische Universität Darmstadt- 26 -

Multi-wiredrift chambers

WINDS

Dipole magnet
NEBULA

n
n

11Li

p

Plastic
scintillators
MINOS

RPD
1m

re r
wi
e
lti- mb
Mu t cha
f
dri

tor

lla

nti

sci
9Li
stic
Pla aysarr

Fig. 1. Schematic of the setup.

to produce the excited 11 Li. The decay mode of the9
Li + 2n channel was investigated through the energy
sharing between the two-body subsystems and it was
found that in most cases 11 Li decays through 10 Li, i.e.,emitting the two neutrons sequentially.8)
From the interest of the tensor force, the formation of deuteron clusters in 11 Li was investigated using the deuteron knockout reaction. Since deuterons
are weakly bound systems, approximately half dissociates during the knockout process. However, choosing
the appropriate kinematics can distinguish deuteronoriginated protons and protons from proton knockout.
The deuteron spectroscopic factor could be obtained bycomparing it with the distorted-wave impulse approximation (DWIA) calculation, though it contains large
systematic uncertainties.9)
The proton knockout channel was also investigated
for the 10 He spectroscopy. A three-body correlation
analysis showed convincing result on the long-debatedground state of 10 He.10)
In summary, 11 Li was comprehensively studied using
the quasi-free knockout reaction. In addition to twoneutron correlation in the ground and excited states,
the structure of unbound subsystems and the formationof deuteron clusters were investigated.
References
1) A. B. Migdal, Soviet J. Nucl. Phys. 16, 238 (1973).
2) Y. Kikuchi et al., Prog. Theor. Exp. Phys. 2016,
103D03 (2016).
3) A. Obertelli et al., Eur. Phys. J. A 50, 8 (2014).
4) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
5) Y. Li, SAMURAI International Workshop (2022).
6) Y. Kubota et al., Phys. Rev. Lett. 125, 252501 (2020).
7) A. Corsi et al., Phys. Lett. B 840, 137875 (2023).
8) P. André, Direct Reactions with Exotic Beams (2022).
9) M. Miwa, Direct Reactions with Exotic Beams (2018).
10) Y. L. Sun, Direct Reactions with Exotic Beams (2022).

Ⅱ-1. Nuclear Physics
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Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Analysis of 48 Cr(p, n) reaction in inverse kinematics
M. Sasano,∗1 J. Gao,∗1,∗3 L. Stuhl,∗9,∗22 Y. Hirai,∗4 T. Wakasa,∗4 D. S. Ahn,∗1 J. K. Ahn,∗13 H. Baba,∗1
K. Chae,∗20 A. Chilug,∗5,∗1 K. Cook,∗15 Y. Fujino,∗7 N. Fukuda,∗1 B. Gao,∗19 S. Goto,∗4 I. S. Hahn,∗8,∗22
Y. Hamano,∗4 Z. Halász,∗9 T. Harada,∗10,∗1 S. Hong,∗20 S. Huang,∗1,∗3 N. Inabe,∗1 D. Inomoto,∗4 T. Isobe,∗1
H. Kasahara,∗4 D. Kim,∗8 T. Kobayashi,∗14,∗1 Y. Kondo,∗15,∗1 Z. Korkulu,∗1 A. Krasznahorkai,∗9 H. Miki,∗15
K. Miki,∗14,∗1 S. Mitsumoto,∗4 M. Miwa,∗18,∗1 T. Motobayashi,∗1 T. Nakamura,∗15,∗1 M. Nishimura,∗1
H. Oshiro,∗4 H. Otsu,∗1 V. Panin,∗1 S. Sakaguchi,∗4,∗1 D. Sakai,∗14 H. Sakai,∗1 S. Sakaki,∗4 H. Sato,∗1
T. Shimada,∗15 Y. Shimizu,∗1 B. Sun,∗21 X. Sun,∗1,∗3 H. Suzuki,∗1 J. Tanaka,∗1 Y. Togano,∗7,∗1 T. Tomai,∗15,∗1
T. Uesaka,∗1 Y. Utsuki,∗14 H. Wang,∗15,∗1 X. Xu,∗19 K. Yako,∗2 A. Yasuda,∗15 K. Yoneda,∗1 K. Yoshida,∗1
Y. Yoshitome,∗15 and J. Zenihiro∗1
In this paper, we report on the progress in the data
analysis of the SAMURAI11 experiment performed at
the RI Beam Factory (RIBF) of RIKEN Nishina Center in spring, 2019. This experiment was conducted
to measure the (p, n) reaction on N = Z unstable nuclei, namely, 48 Cr and 64 Ge. Previously, in Refs. 1)
and 2), we reported on the experimental setup and theparticle identiﬁcation (PID) analysis of the reaction
residues with the SAMURAI spectrometer,3) respectively. In Ref. 4), we reported on the observation ofa kinetic curve in the recoil-neutron data produced in
the 48 Cr(p, n)48 Mn reaction, under the condition thatthe reaction residues 47 Cr were selected through PID
analysis.
Figure 1 shows a plot of neutron kinetic energy
vs. neutron scattering angle in the laboratory frame
for those events in which the reaction residues 46 V
were selected through PID analysis. The 46 V residues
were populated through the two-proton decay from the48
Mn. There was no clear locus along the calculated
kinetic curves in 48 Mn, above the two-proton separation energy at 6.828 MeV. The plot contains events
due to the background in a low neutron-kinetic-energy
region below 500 keV.
A further analysis is ongoing to substract the back-Fig. 1. A two-dimensional plot of neutron kinetic energy vs.
neutron scattering angle in the laboratory frame. The
reaction residues 46 V were selected through the PID
analysis. The solid and dashed curves represent calculated kinetic curves for excitation energies and scattering angles in the center-of-mass system of the 48 Cr(p, n)reaction, respectively.

ground. We are working on the background evaluationby using the reaction channels where the (p, n) reaction does not occur, following the method utilized in aprior study.5)
We are grateful to the RIKEN accelerator staﬀ and
CNS, University of Tokyo, for their continuous eﬀorts
to accomplish this stable beam acceleration.

∗1

RIKEN Nishina Center∗2 Center for Nuclear Study, University of Tokyo∗3 School of Physics, Peking University∗4 Department of Physics, Kyushu University∗5 Horia Hulubei National Institute for R&D in Physics andNuclear Engineering∗7 Department of Physics, Rikkyo University∗8 Department of Physics, Ewha Womans University∗9 Institute for Nuclear Research (ATOMKI)∗10 Department of Physics, Toho University∗11 KVI - CART, University of Groningen∗12 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗13 Department of Physics, Korea University∗14 Department of Physics, Tohoku University∗15 Department of Physics, Tokyo Institute of Technology∗16 Department of Physics, University of Tokyo∗18 Department of Physics, Saitama University∗19 Institute of Modern Physics, Chinese Academy of Sciences∗20 Department of Physics, Sungkyunkwan University∗21 School of Physics and Nuclear Engineering, Beihang University∗22 Center for Exotic Nuclear Studies, Institute for Basic Science

References
1) M. Sasano et al., RIKEN Accel. Prog. Rep. 53, 40(2019).
2) J. Gao et al., RIKEN Accel. Prog. Rep. 54, 14 (2020).
3) T. Kobayashi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 294 (2013).
4) M. Sasano et al., RIKEN Accel. Prog. Rep. 55, 22(2022).
5) M. Sasano et al., Phys. Rev. C 86, 034324 (2012).

- 27 -

Ⅱ-1. Nuclear Physics

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RIKEN
Accel. Prog. Rep. 56 (2023)

26

Si + α resonant scattering measurement to study 26 Si(α, p)29 P
reaction rate

M. J. Kim,∗1 K. Y. Chae,∗1 K. Okawa,∗2 S. Hayakawa,∗2 S. Adachi,∗3 S. M. Cha,∗4 T. Chillery,∗2 N. N. Duy,∗1
T. Furuno,∗3 G. M. Gu,∗1 S. Hanai,∗2 N. Imai,∗2 D. Kahl,∗5 T. Kawabata,∗3,∗6 C. H. Kim,∗1 D. Kim,∗4
S. H. Kim,∗1 S. Kubono,∗6 M. S. Kwag,∗1 J. Li,∗2 N. R. Ma,∗2 S. Michimasa,∗2 K. Sakanashi,∗3 H. Shimizu,∗2
O. Sirbu,∗5 N. K. Uyen,∗1 H. Yamaguchi,∗2 R. Yokoyama,∗2 and Q. Zhang∗2
An X-ray burst can be characterized by a sudden
and intense release of X-ray radiation from a compact
stellar object such as a neutron star. A total energy
release of approximately 1039–40 ergs can be achieved
per burst in just a few seconds. It is believed thatthe proton-rich nuclei up to the Sn-Sb-Te region canbe synthesized during the burst. To better understandthe X-ray bursts, studying the 26 Si(α, p)29 P reaction
is essential since 26 Si is considered to be one of the
waiting points in the nucleosynthesis.
A sensitivity study, which identiﬁes the importantnuclear reaction rates that aﬀect the X-ray light curves
or ash composition, suggests that the 26 Si(α, p)29 P is
one of the impactful reactions to the light curve of
the X-ray burst.1) Despite its importance, the study of
26
Si(α, p)29 P is less understood experimentally. Thus
we have performed a 26 Si + α experiment to measure the 26 Si(α, p)29 P reaction directly and the resonant scattering to investigate resonances in 30 S, which
can be populated in the 26 Si(α, p)29 P reaction as intermediate states. The result on the 26 Si + α resonant
scattering is described in this report.
The 26 Si + α resonant scattering was measured
at the Center for Nuclear Study Radioactive Ion
Beam Separator (CRIB)2) of the University of Tokyo.
The radioactive 26 Si beam was produced at E =2.14 MeV/nucleon through the 3 He(24 Mg, n)26 Si reaction by impinging 24 Mg at E = 7.56 MeV/nucleon ona cryogenic 3 He gas target.3) The 26 Si beam was separated and puriﬁed by combining the magnetic analysis
and velocity selection with a double achromatic system
and a Wien ﬁlter. Two PPACs were located at the upstream of the reaction target for the event-by-event
monitoring of beam position and time-of-ﬂight. The
typical 26 Si beam intensity was 2.8 × 104 pps, and thebeam purity was ∼16%. The 26 Si beam was impinged
on the 4 He gas target with a pressure of 250 Torr. The
reaction target was kept at room temperature. The
thick target method is adopted for the experiment toscan a wide excitation energy range in 30 S.
The light charged particles were measured by silicon detector telescopes. Using four layers of silicon
∗1
∗2
∗3
∗4
∗5
∗6

detectors (∆E1, ∆E2, E1, and E2 layer), each speciesof charged particles could be easily identiﬁed. The∆E1 and ∆E2 detectors are segmented into 16 strips
providing the horizontal and vertical position information, respectively. The E1 and E2 detectors are
pad type silicon detectors. The scattering angle wasobtained based on the position information. To obtain the excitation function of 26 Si(α, α)26 Si reaction,
the α energies were converted to the center-of-massenergy by considering the kinematics of the reaction
and the energy loss of particles in the gas target. Figure 1 shows the excitation function obtained at θC.M.
= 174◦ . Fitting the experimental excitation function
with the theoretical R-matrix calculations, we will extract resonance parameters of levels in the 30 S, such as
excitation energy, spin, parity, and α partial width, toconstrain the 26 Si(α, p)29 P reaction rate.
250d/dc.m.[mb/sr]

200
150
100
50
0
2

3

4
5
6
7
Center of mass energy [MeV]8

Fig. 1. Excitation function of 26 Si + α elastic scattering at
θc.m. = 174◦

References
1) R. H. Cyburt et al., Astrophys. J. 55, 830 (2016).
2) Y. Yanagisawa et al., Nucl. Instrum. Methods Phys.
Res. A, 539, 74 (2005).
3) H. Yamaguchi et al., Nucl. Instrum. Methods Phys. Res.
A 589, 150 (2008).

Department of Physics, Sungkyunkwan University
Center for Nuclear Study, University of Tokyo
Department of Physics, Osaka University
Center for Exotic Nuclear Studies, Institute for Basic Science (IBS)
Extreme Light Infrastructure Nuclear Physics (ELI-NP)
RIKEN Nishina Center- 28 -

Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Yield investigation of neutron-rich W isotopes produced bymulti-nucleon transfer reactions of 136 Xe + nat Ir
M. Mukai,∗1,∗2 Y. Hirayama,∗3 Y. X. Watanabe,∗3 P. Schury,∗3 A. Andreyev,∗4 S. C. Jeong,∗3 H. Miyatake,∗3
T. Niwase,∗3 M. Reponen,∗5 M. Rosenbusch,∗3 H. Ueno,∗2 and M. Wada∗3
Nuclear charge radius is a quantity sensitive tochanges in nuclear structure, such as shape transition,
shell closure, and proton-neutron pairing. The nuclei
around Z = 72–78 are known as transitional nuclei,
which exhibit a multitude of nuclear shapes dependingon the neutron and proton numbers.1) In the W isotopic chain, nuclear shape evolution has been investigated up to 190 W in terms of the properties of the ﬁrst
2+ , 4+ excited states2) and K-isomers3) via γ-ray spectroscopy using relativistic ions produced in fragmentation reactions. However, laser spectroscopic dataobtained using low-energy isotope separator on-line(ISOL) beams are lacking, especially in the neutronrich side of this nuclear region,4) due to the refractory nature of these elements. Thus, to investigate theground state shape evolution with the help of theoretical calculations, we are planning to study the change
in nuclear mean-square charge radii of neutron-rich
188, 190
W via in-gas-cell laser ionization spectroscopy5)
at KISS.6) As a preliminary eﬀort, we report the measured extraction yields of 188–190 W isotopes at KISS.
The KISS facility at which we conducted the measurement is an argon-gas-cell-based laser ion source
combined with an ISOL, designed to produce otherwise
diﬃcult-to-access nuclides by multi-nucleon transfer(MNT) reactions. Neutron-rich W isotopes were produced in MNT reactions using an 136 Xe beam (30 particle nA, 10.75 MeV/nucleon) impinging upon a nat Ir(22.7 mg/cm2 ) target. The target-like fragments were
stopped and neutralized in a gas cell pressurized to
75 kPa with puriﬁed Ar gas. The neutralized W
atoms were transported by gas ﬂow and ionized byelement-selective laser resonance ionization at the gas
cell exit. The W atoms were resonantly excited bylaser irradiation at λ1 = 260.7165 nm (5d4 6s2 5 D0 →J= 1◦ ),7) followed by non-resonant excitation to continuum states by laser irradiation at λ2 = 308 nm
from an XeCl laser. The post-accelerated ions (E =20 keV/q) were mass separated using a dipole magnet
with a mass resolving power of m/Δm∼900. After being thermalized in a gas cell cooler-buncher8) (GCCB),
the ions were analyzed in a multi-reﬂection time-ofﬂight (MRTOF) mass spectrograph for isobaric identiﬁcation and ion counting. At a typical mass resolving
power of m/Δm∼500,000,9) the overall eﬃciency of
∗1
∗2
∗3
∗4
∗5

MRTOF+GCCB was 2%.
Figure 1 shows time-of-ﬂight spectra for A/q = 95
ions measured with (black) and without (red) resonant laser excitation of 190W. An enhancement of190
W ion counts accompanying resonant laser irradiation can be clearly observed. In addition to laser
ionized 190W, we observed intense isobaric contaminants consisting of 190Re, 190Os, 190Ir, 190Pt, and190
Au, which are produced with much higher yields
than the more neutron-rich 190W; whether they are
non-resonantly ionized alongside the 190W or the resultof a non-neutralized fraction in the argon gas remains
uncertain. The recent improvements in MRTOF performance9) at KISS allowed for the successful counting of 190W2+ ions in spite of these intense isobaric
contaminants. A similar situation was encountered inmeasurements of 188, 189W. The measured extraction
yields of 188, 189, 190W were 65, 5.6, and 1.6 pps, respectively. These yields are suﬃcient to perform future
in-gas-cell laser ionization spectroscopy.


2V



3W ,U



5H





:

$X

&RXQWVQV






−







WLPHRIIOLJKW QV

Fig. 1. Measured time-of-ﬂight spectra with resonant excitation laser ON (black) and OFF (red) for 190 W.

References
1) R. F. Casten, Nucl. Phys. A 443, 1 (1985).
2) N. Alkhomashi et al., Phys. Rev. C 80, 064308 (2009).
3) G. J. Lane et al., Phys. Rev. C 82, 051304(R) (2010).
4) P. Campbell et al., Prog. Part. Nucl. Phys. 86, 127(2016).
5) M. Mukai et al., Phys. Rev. C 102, 054307 (2020).
6) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 412, 11 (2017).
7) NIST
AtomicSpectraDatabase,https://physics.nist.gov/asd .
8) Y. Ito et al., JPS Conf. Proc. 6, 030112 (2015).
9) P. Schury et al., in this report.

RIKEN Nishina Center
Graduate School of Engineering, Nagoya University
Wako Nuclear Science Center (WNSC), IPNS, KEK
School of Physics, Engineering and Technology, University
of York
Department of Physics, University of Jyväskylä- 29 -

Ⅱ-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

First application of mass measurements with the Rare-RI ring
reveals the solar r-process abundance trend at A = 122 and A = 123†
H. F. Li,∗1 S. Naimi,∗2 T. M. Sprouse,∗3 M. R. Mumpower,∗3 Y. Abe,∗2 Y. Yamaguchi,∗2 D. Nagae,∗2
F. Suzaki,∗3 M. Wakasugi,∗2 H. Arakawa,∗4 W. B. Dou,∗4 D. Hamakawa,∗4 S. Hosoi,∗4 Y. Inada,∗4 D. Kajiki,∗4
T. Kobayashi,∗4 M. Sakaue,∗4 Y. Yokoda,∗4 T. Yamaguchi,∗4 R. Kagesawa,∗5 D. Kamioka,∗5 T. Moriguchi,∗5
M. Mukai,∗5 A. Ozawa,∗5 S. Ota,∗6 N. Kitamura,∗6 S. Masuoka,∗6 S. Michimasa,∗6 H. Baba,∗2 N. Fukuda,∗2
Y. Shimizu,∗2 H. Suzuki,∗2 H. Takeda,∗2 D. S. Ahn,∗2 M. Wang,∗1 C. Y. Fu,∗1 Q. Wang,∗1 S. Suzuki,∗1 Z. Ge,∗1
Y. A. Litvinov,∗7 G. Lorusso,∗8,∗9 P. M. Walker,∗9 Zs. Podolyak,∗9 and T. Uesaka∗2
The rapid neutron capture process (r-process) is responsible for synthesizing about half of the elements
beyond iron up to bismuth, as well as all of the thorium and uranium. Masses of the neutron-rich nuclides are essential input parameters for the r-processsimulation. However, most of the nuclides involved in
the r-process can not be produced in the laboratory.
Usually, the masses predicted by the theoretical massmodels are used. Not only does measuring the massof exotic nuclei provide dependable experimental datafor r-process calculations, but it also plays a crucialrole in improving mass models.
The Rare-RI Ring at RIBF is a newly commissioned
cyclotron-like storage ring mass spectrometer.1) We
performed the mass measurement experiment for the
exotic nuclei on the southwest of the 132 Sn with R3.
In this experiment, ﬁve N = 77 isotones, 127 Sn, 126 In,
125
Cd, 124 Ag, 123 Pd, were produced by the in-ﬂight
ﬁssion of 238 U beam, selected by the BigRIPS and ﬁnally injected into the R3. Details of the experimentcan be found in the previous report.2) Masses of 126 In,
125
Cd, and 123 Pd were measured whereby the mass
uncertainty of 123 Pd was improved.
We investigate the impact of the new mass valueof 123 Pd on the solar r-process abundances in the rprocess by employing the Portable Routines for Integrated nucleoSynthesis Modeling reaction network.3)
Reaction network calculations of 20 trajectories with a
speciﬁc entropy 40 kB /baryon, expansion timescale τ= 20 ms and varying electron fraction Ye from 0.15 to
0.35 in steps of 0.01 are performed. The A = 122 to
A = 123 abundance ratio for each trajectory with the
new mass result is calculated and compared with thebaseline model in which the mass value of the 123 Pd
is taken from FRDM2012,4) as shown in Fig. 1. We
ﬁnd that the abundance ratio of each trajectory in thebaseline model is smaller than the solar ratio, making
†
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Fig. 1. Ratio of the A = 122 to A = 123 isotopic abundances as a function of electron fraction for the baseline model (gray line) and if our new mass measurement(red line) and its uncertainty (red band) are included.
The horizontal black line indicates the value of the sameratio in the solar r-process residuals of Ref. 5).

it impossible to reproduce the observed feature withany combination of trajectories. However, when the
newly measured 123 Pd mass was used, the ratio is sufﬁciently varied across the range of trajectories. Thisvariability makes it possible to use suitable linear combinations of trajectories to reproduce the observed ratio. The increase in the abundance ratio is attributed
to changes in calculated nuclear properties resulting
from the newly measured 123 Pd mass. The neutron
capture cross section for 122 Pd decreases by a factorof 2.6 and for 123 Pd increases by a factor of 2.2, while
the probability for the β-delayed neutron emission of123
Rh increases by 14% with the updated mass. This
results in the material pileup along the A = 122 isobar
relative to the baseline.
References

Condensed from the article in Phys. Rev. Lett. 128, 153001(2022)
Institute of Modern Physics, Chinese Academy of Sciences
RIKEN Nishina Center
Theoretical Division, Los Alamos National Laboratory
Department of Physics, Saitama University
Institute of Physics, University of Tsukuba
Center for Nuclear Study, University of Tokyo
GSI Helmholtzzentrum für Schwerionenforschung GmbH
National Physical Laboratory
Department of Physics, University of Surrey

1) S. Naimi et al., Eur. Phys. J. A 59, 90 (2023).
2) S. Naimi et al., RIKEN Accel. Prog. Rep. 52, 102(2019).
3) T. M. Sprouse et al., Phys. Rev. C 101, 055803 (2019).
4) P. Möller et al., At. Data Nucl. Data Tables 109, 1(2016).
5) M. Arnould et al., Phys. Rep. 450, 97 (2017).

- 30 -

Ⅱ-1. Nuclear Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Direct determination of the atomic mass of 189 W
M. Mukai,∗1,∗2 Y. Hirayama,∗3 P. Schury,∗3 Y. X. Watanabe,∗3 S. C. Jeong,∗3 H. Miyatake,∗3
T. Niwase,∗3 M. Rosenbusch,∗3 H. Ueno,∗1 and M. Wada∗3
We measured the atomic mass of 189 W in an experiment to investigate the yields of 188 – 190W1) produced
in multi-nucleon transfer (MNT) reactions for futurelaser ionization spectroscopy at the KEK Isotope Separation System (KISS).2) The mass of 189
74W has previously been determined from Qβ 3) and via Schottky
mass spectroscopy at ESR,4) but both were excluded
from the Atomic Mass Evaluation (AME2020)5) basedon deviations from the trends of the mass surface, making a complementary mass evaluation highly desirable.
We have produced 189W at KISS in MNT reactionsof 136Xe + nat Ir and used the multi-reﬂection time-ofﬂight mass spectrograph (MRTOF-MS) for ion counting, isobaric identiﬁcation, and atomic mass determination. A detailed description of the experiment isgiven in Ref. 1).
The identiﬁcation of 189W was achieved by conﬁrming that the relative intensity of the 189W TOF spectral peak reduced signiﬁcantly when the resonant excitation laser was turned oﬀ. After correcting for TOF
drift, e.g., from thermal expansion of the MRTOF-MS,
the mass resolving power was m/∆m∼500,000.6) Figure 1 provides the drift-corrected sum total measured
spectrum for ions with mass-to-charge ratio A/q =189/2 with and without laser ionization applied. Leastsquares ﬁtting of the spectrum was performed to determine the TOF values of extracted isobars. The TOF
for each ion species was determined using a Gaussianexponential hybrid function with exponential tails on
one side. The shape parameters were determined froma high-statistics TOF spectrum of the elastic particle
191 2+
Ir and scaled based on A/q. From the evaluatedpeak positions (t and tref ), the mass value (m) was

calculated using
m=

q
qref

mref

(

t − t0tref − t0)2(1)

where t0 is constant oﬀset, while mref , qref , and tref
are the mass, charge, and TOF of a reference ion, respectively. The t0 term was determined from Eq. (1)based on the results of high-statistics measurements of85
Rb and 190Os, which have well-known atomic masses.
To limit mass-dependent systematic errors, nearly isobaric 190Os2+ was used as a reference ion along with85
Rb in a double-referencing scheme.7) Among the observed A/q = 189/2 ions, 189Os has a long-lived isomer(Eex = 30.82(2) keV, T1/2 = 5.8(1) h),8) which can beextracted from the KISS gas cell but cannot be resolved by the MRTOF-MS. Due to the minimal TOF
diﬀerence between 189g Os2+ and 189m Os2+ , a single
peak was ﬁtted, and the evaluated mass represents theweighted average of the two states.
Figure 2 shows the diﬀerences between our measured
mass values and the AME2020 evaluation. Our measured mass values of 189Re, 189Os, 189Ir, and 189Pt
are in good agreement with the evaluated values. Our
measured mass for 189W is within the AME2020 error band and is also consistent with the previously reported values in Refs. 3) and 4). This provides someconﬁrmation of the validity of the previous data.

βCounts/1.6 ns102

Fig. 2. Diﬀerences between our measured mass values and
AME2020 evaluation. The AME2020 error bands are
represented by yellow and green stripes.

10

1

-80

-60

-40

-20

0

20

time-of-flight  10389560 (ns)40

References601) M. Mukai et al., in this report.
2) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 412, 11 (2017).
3) P. Kauranen et al., J. Inorg. Nucl. Chem. 27, 1451
(1965).
4) D. Shubina et al., Phys. Rev. C 88, 024310 (2013).
5) W. J. Huang et al., Chin. Phys. C 45, 030002 (2021).
6) P. Schury et al., in this report.
7) P. Schury et al., Phys. Rev. C 95, 011305(R) (2017).
8) T. D. Johnson et al., Nucl. Data Sheets 142, 1 (2017).

Fig. 1. Measured TOF spectra of A/q = 189/2 ions. The
colored curves show the best ﬁtting curves to the data.
Solid vertical lines show the ﬁtted TOF position of eachisobar.
∗1∗2∗3

RIKEN Nishina Center
Graduate School of Engineering, Nagoya University
Wako Nuclear Science Center (WNSC), IPNS, KEK- 31 -

2. Nuclear Physics (Theory)Ⅱ-2. Nuclear Physics (Theory)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Spatial correlation of a particle-hole pair with a repulsive isovector
interaction†
K. Hagino∗1 and H. Sagawa∗2,∗3
It has been well recognized that the pairing correlation among valence neutrons plays a decisive role inthe structure of weakly bound nuclei. In particular,
there have been several theoretical studies of a strong
dineutron correlation, in which two neutrons attract
each other and show a large probability of a two-bodywave function with a small correlation angle in the coordinate space. A strong signature of the dineutron
correlation has also been experimentally observed inseveral weakly bound nuclei such as 11 Li, 6 He, and19
B.
It would be an interesting question to ask what happens to the spatial correlation when the interaction
is repulsive rather than attractive. Besides the trivial Coulomb repulsion between protons, a well-known
repulsive interaction in nuclear physics is the isovector particle-hole (p-h) interaction, which plays an important role in generating collective giant dipole resonances (GDRs). In this paper, we pursue the correlation induced by the repulsive interaction, studying
nuclei with one neutron particle and one proton hole
on top of a doubly magic nucleus, such as 56 Co (=56
Ni+n−p) and 40 K (= 40 Ca+n−p). To construct thedensity distribution for the p-h state, we perform theHartree-Fock (HF) plus Tamm-Dancoﬀ approximation(TDA) with Skyrme-type interactions.
The spatial distribution for the proton hole in thetwo-dimensional (z, x) plane is shown in Fig. 1(a) for
the 4+ state in 56 Co with the azimuthal angular momentum component M = 0. The reference neutron(2p3/2 particle state) is placed at (z, x) = (3.7, 0.0) fm.
The upper panel shows the unperturbed case with thewave function. As expected, the hole wave
(1f7/2 )−1pfunction (1f7/2 )−1
p has two symmetric peaks at the positions opposite to the center of the core nucleus. The
correlated hole density, in which the p-h repulsive interaction is active, is shown in Fig. 1(b). One can see
a strong repulsive correlation, where the component
close to the reference neutron-particle state is largely
hindered. This is analogous to the Coulomb hole observed in many-electron systems and is completely opposite to the dineutron conﬁguration, in which the twovalence neutrons mainly remain on the same side of thetwo-dimensional plane with a small relative distance,that is, a small correlation angle.
In Ref. 1), as an outcome of the repulsive correlation
†
∗1
∗2
∗3

(a)

6x10

-6

4

5x10

-6

2

4x10-6

0

3x10

-6

-2

2x10

-6

-4

1x10

-6

x (fm)

6

-6

(b)

-6

-4

-2

6

0 2
z (fm)4

0 2
z (fm)

4

6

x (fm)

4
2
0

-2
-4
-6

-6

-4

-2

6

0

2x10-5-5
1.8x10-5
1.6x101.4x10-5
1.2x10-5
1x10-58x10-6
6x10-6
-6
4x10
-6
2x10
0

Fig. 1. Uncorrelated (upper panel) and correlated (lower
panel) proton-hole distributions in the two-dimensional(z, x) plane for the 4+ state in 56 Co when the neutronparticle is located at (z, x) = (3.7, 0.0) fm indicatedby a white circle. The azimuthal angular momentum
component is set to be M = 0.

of an isovector p-h pair, a suppression of a groundstate-to-ground-state deuteron transfer reaction, e.g.,54
Fe(3 He, p)56 Co, was pointed out. Note that the two
proton holes in 54 Fe prefer the spatial conﬁguration inwhich the two holes are close to each other. If oneof those proton holes is ﬁlled in via deuteron transfer, the neutron in the deuteron and the other proton hole would be located close to each other. This
would correspond to an excited state of 56 Co; thus,
the transfer to the ground state of 56 Co would belargely suppressed. It would be interesting future
work to estimate the transfer cross sections with thecoupled-reaction-channel method or second-order distorted wave Born approximation.

Condensed from the article in Phys. Rev. C 106, 034313(2022)
Department of Physics, Kyoto University
RIKEN Nishina Center
Center for Mathematics and Physics, University of Aizu

Reference
1) G. F. Bertsch, Phys. Lett. B 25, 62 (1967).

- 33 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Momentum-space structure of dineutron in 11 Li†
M. Yamagami ∗1
A recent knockout-reaction experiment for the Borromean nucleus 11 Li measured the mean correlation angle between the momenta of emitted neutrons n1 and n2
in the reaction channel 11 Li(p, pn1 )10 Li∗ → 9 Li + n2 .1)
The dependence on the missing momentum k of n1 is
considered to reﬂect the spatial structure of dineutron.
Here, the reﬂection of the spatial structure of dineutron to the mean opening angle between the momenta
k1 and k2 of the valence neutrons at the ground state of11
Li is discussed. Further, the similarities with the mean
correlation angle are highlighted.
A three-body model calculation is performed in the
momentum space using a ﬁnite-range n–n interaction,
which reproduces the two-neutron (2n) separation energy and the matter radius of 11 Li. Further, the 2n
density, ρ2 (k1 , k2 , θk ), is calculated using k1 = |k1 |,k2 = |k2 |, and the opening angle between k1 and k2 ,
θk . Figure 1(a) shows ρ2 (k1 , k2 , θk ) as a function of both
k1 = k2 = kn and θk . Figure 1(b) shows the 2n density inreal space via the Fourier transformation, ρ2 (r1 , r2 , θr ),using the radial coordinates, r1 = r2 = r, and opening
angle, θr .

of k1 = kn as follows[∫ kcut∫ πcos ⟨θk ⟩ ≡k22 dk2 2π sin θk dθk00]
× ρ2 (kn , k2 , θk ) cos θk /ρk (kn ),(1)

where ρk (kn ) is the one-neutron density distribution.
Figure 2(a) shows ⟨θk ⟩ using the cutoﬀ momenta of
kcut = ∞ (no cutoﬀ) and kcut = ksurf = 0.62 fm−1 .

Fig. 2. (a) Mean opening angle ⟨θk ⟩ as a function of k1 = kn
for 11 Li. “Surface” indicates the cutoﬀ of kcut = ksurf . (b)Same as (a) but for 6 He, 22 C, and 19 B.

Fig. 1. (a) 2n density for 11 Li as functions of k1 = k2 = kn
and the opening angle θk . It is weighted with a factor of
8π 2 kn4 sin θk . (b) Same as (a) but 2n density in real spaceas functions of r1 = r2 = r and the opening angle θr . It
is weighted with a factor of 8π 2 r4 sin θr .

The dineutron conﬁguration is obtained at the lowmomentum of (kn , θk ) = (0.18 fm−1 , 128◦ ). It is accompanied by the broad angular distribution, and the longkn -tail indicates the strong dineutron correlation (thehigh n–n relative momentum).
The mean opening angle ⟨θk ⟩ is deﬁned as a function†∗1

Condensed from the article in Phys. Rev. C 106, 044316 (2022)
Department of Computer Science and Engineering, Universityof Aizu⟨θk ⟩ (no cutoﬀ) exhibits a peak at kn = 0.27 fm−1 ;however, it gradually increases above kn ≈ 0.5 fm−1 .
ksurf characterizes the low-momentum halo region by
k1 , k2 < ksurf . ⟨θk ⟩ using kcut = ksurf exhibits a peakat kn = 0.31 fm−1 and a plateau of ⟨θk ⟩ ≈ 82◦ abovekn ≈ 1.0 fm−1 . These features are consistent with theobserved k dependence of the mean correlation angle (thepeak at k ≈ 0.3 fm−1 and the plateau of approximately
87◦ above k ≈ 0.9 fm−1 ),1) which is considered to reﬂect
the 2n correlations in the surface region.2)
In conclusion, the manner in which the mean opening
angle reﬂects the 2n density in 11 Li was discussed. For⟨θk ⟩, the importance of the surface eﬀect and the similarities with the mean correlation angle in the knockout
reaction were highlighted. The same conclusion was obtained for 6 He, 22 C, and 19 B (see Fig. 2(b)), wherein
the measurement of the momentum dependence of theangular correlations between the halo neutrons can provide useful information on dineutron correlations at low
density.
References
1) Y. Kubota et al., Phys. Rev. Lett. 125, 252501 (2020).
2) J. Casal et al., Phys. Rev. C 104, 024618 (2021).

- 34 -

Ⅱ-2. Nuclear Physics (Theory)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

He cluster formation in light neutron-rich nuclei†
H. Motoki,∗1 S. Shin,∗1 Y. Suzuki,∗2 Q. Zhao,∗3 B. Zhou,∗4 and M. Kimura∗5
Recently, a negative correlation between the neutron
number and 4 He cluster formation probability on the
nuclear surface was experimentally reported for Sn isotopes.1) A similar trend was theoretically observed for
C isotopes.2) However, this trend contradicts to the previous expectation; 4 He clustering develops toward theneutron drip-line of Be and B isotopes.3) To understandthese ambiguous results, we have quantitatively evaluated the 4 He cluster formation probability based on theantisymmetrized molecular dynamics (AMD).
Figure 1 shows the calculated intrinsic proton density
distributions of the ground states.4) Except for 11 B, thedistributions exhibit two peaks, indicating the formation of He + He and He + He clusters in Be and B isotopes, respectively. The development of clusters can be
estimated from the distance between the clusters (distance between two peaks), which is shown in the lower
panel of Fig. 1. It suggests a gradual growth of clusters
toward the drip line, which is qualitatively consistent
with the previous expectation.3)

A′⟨δ(x − r)ΦHe ΦA′ Yl=0 (x̂)]0 |ΦA ⟩ ,where ΦHe , ΦA′ and ΦA denote the wave functions of
the He cluster, daughter, and target nuclei. RWA is
the probability amplitude to determine the He cluster
at distance r from the daughter nucleus. Hence, itssquare integral (herein referred to as S-factor) deﬁnes
the cluster formation probability.
The results are denoted by solid lines in Fig. 2. Unexpectedly, the S-factor decreases as neutron number increases. This contradicts the results illustrated in Fig. 1
and previous expectation;3) however, this trend remains
consistent in Sn isotopes.1) To resolve this issue, we investigated the formation probabilities of 6 He and 8 Heclusters (Fig. 2). The 6 He and 8 He clusters dominate
over the 4 He cluster as neutron number increases. Considering the sum of the formation probabilities of He
isotopes, we observe an increasing trend, as shown in
Fig. 1.

S-factor

0.3

12Be

10Be

14Be

0.2

0.2

S(4He)11B

S(8He)

S(6He)
13B

15B

17B

0.1

19B

0.1

15B

13B

11B

S(4He)

17B

0.0

0.3

cluster distance (fm)

3.0

6

8
neutron number

13B 4He 4He

0.0

Sum
0.0

10

8

4He

15B

6He

6

10Be

12Be

14Be

0.0

10
12
neutron number

14

17B

6He

6He

8He

8He

0.1
2.0

4.0

6.0

2.0

4.0

6.0

2.0

4.0

6.0

-0.1

2.0
1.0

Sum

S(6He)

0.2

4.0

(1)

0.4

14Be

12Be

√( )
A

S-factor

10Be

rY(r) =

11B

6

13B

8

15B

17B

Fig. 2. Upper panels show the 4 He, 6 He and 8 He cluster
formation probabilities. The lower panels show the RWAof the 4 He, 6 He and 8 He clusters in B isotopes.

Be
B

10
12
Neutron number

14

To quantitatively evaluate He cluster formation andrelate it to 4 He knockout reaction, we calculated the
reduced width amplitude (RWA).

The aforementioned results may be summarized asfollows: In neutron-rich Be and B isotopes, 4 He is
formed as a cluster core; however, but it is always accompanied by excess neutrons. As a result, we should
sum up the 4 He clusters and 6, 8 He clusters to accurately
evaluate the cluster formation probability. We believethat this new insight is important for future studies tounderstand the relationship between clustering and excess neutrons.

†

References

Fig. 1. Upper panels show the intrinsic proton density distribution where peaks of the density distribution areplotted by ﬁlled circles. Lower panel shows the distance
between cluster centroids, i.e. inter-cluster distance.

∗1
∗2
∗3
∗4
∗5

Condensed from the articles in Eur. Phys. J. A 57, 1 (2021)
and Prog. Theor. Exp. Phys. 2022, 113D01 (2022)
Department of Physics, Hokkaido University
Research Center for Nuclear Physics, Osaka University
School of Science, Huzhou University
Institute of Modern Physics, Fudan University
RIKEN Nishina Center- 35 -

1) J. Tanaka et al., Science 371, 260 (2021).
2) Q. Zhao et al., Eur. Phys. J. A 57, 1 (2021).
3) Y. Kanada-En’yo et al., Phys. Rev. C 52, 647 (1995).
4) H. Motoki et al., Prog. Theor. Exp. Phys. 2022, 113D01(2022).

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)†
Energy spectrum of 15
Ξ C and the ΞN two-body interaction
Y. Tanimura,∗1,∗2 H. Sagawa,∗3,∗4 T. -T. Sun,∗5 and E. Hiyama∗1,∗4
Studying the interaction of the strangeness S = −2
sector is important in hypernuclear physics for a uniﬁed understanding of baryon-baryon interaction. To
this end, it is crucial to study the structure of doublestrangeness hypernuclei, such as double-Λ and Ξ hypernuclei.
In this work, we focused on new experimental data,
IRRAWADDY event,1) of a 15
Ξ C nucleus observed at
BΞ = 6.27 ± 0.27 MeV. We estimate the strengths of
the N Ξ interaction and give a consistent interpretation
for all the events1–4) of the Ξ hypernucleus including IRRAWADDY. In addition to our previous work
based on the relativistic mean-ﬁeld (RMF) model,5)
we introduce an N Ξ residual interaction and infer thatKINKA (BΞ = 8.00 ± 0.77 or 4.96 ± 0.77 MeV) and
IRRAWADDY events1) are the ground-state spin doublet with the Ξ particle in the s orbit and that IBUKI(BΞ = 1.27 ± 0.21 MeV) and KISO (BΞ = 3.87 ± 0.21
or 1.03 ± 0.18 MeV) events2,4) are members of theexcited-state multiplets with the Ξ particle in the porbits.
To describe the 15
Ξ C nucleus and estimate its energy spectrum, we employ an RMF model and spinisospin dependent residual interaction. Within the
RMF model, we adopt the PK1 parameter set6) for the
nucleon-meson couplings, while the coupling constantsin the hyperon sector are ﬁtted to roughly reproduce
the observed spectrum. Moreover, the eﬀect of theresidual interaction is estimated by ﬁrst-order perturbation theory with the RMF wave functions taken as
the unperturbed states. The 14 N subsystem of the 15
Ξ C
nucleus is described as the p1/2 neutron and protonπcoupled to spin-parity Jnpnp = 1+ and isospin Tnp = 0
12
on top of the inert C core. The Ξ particle is thencoupled to the nucleon pair to make the total quantum number J π T , where J π is the total spin-parity ofthe system, and T = 1/2 in the case of 15
Ξ C.
We consider a residual interaction acting on s and p
waves. The s-wave interaction is given by∑(vσ Σi · ΣΞ + vτ ⃗τi · ⃗τΞVN Ξ =and ⃗τ are the isospin operators. The strength parameters of VN Ξ are ﬁxed based on the HAL QCD
ΞN potential.7) We further introduce a p-wave spindependent interaction given by
∑
←
−
→
−
vσp Σi · ΣΞ ∇ · δ(ri − rΞ ) ∇, (2)VNp Ξ =
i∈nucleons

where vσp is a parameter to be optimized by the measured energies of IRRAWADDY and KINKA events.
Fig. 1(a) shows the energy spectrum of 15
Ξ C as afunction of vσp , which is obtained by assuming that the
IRRAWADDY event is the ground state of 15
Ξ C. It isseen that vσp ∼ −150 MeV.fm5 and ∼100 MeV.fm5
give spectra consistent with all the experimental data.
Fig. 1(b) shows the energy spectrum obtained by assuming that the lower candidate of the KINKA eventis the ground state. In this case, vσp ∼ −150 MeV.fm5
and ∼125 MeV.fm5 give results consistent with the
data.
(a)

Fig. 1. Estimated energy spectrum of 15
Ξ C nucleus as afunction of the p-wave spin-spin interaction strength vσp .
The energies of the levels labeled by the orbital occupied by the Ξ− particle, Ξlj , and the total spin parity,
J π , are represented by lines. The experimental data ofBΞ− are shown by color bands.

i∈nucleons+ vστ Σi · ΣΞ⃗τi · ⃗τΞ )δ(ri − rΞ ),References(1)1) M. Yoshimoto et al., Prog. Theor. Expt. Phys. 2021,
073D02 (2021).
2) K. Nakazawa et al., Prog. Theor. Expt. Phys. 2015,
033D02 (2015)3) E. Hiyama et al., Annu. Rev. Nucl. Sci. 68, 131 (2018).
4) S. H. Hayakawa et al., Phys. Rev. Lett. 126, 062501(2021).
5) T. T. Sun et al., Phys. Rev. C 94, 064319 (2016).
6) W. H. Long et al., Phys. Rev. C 69, 034319 (2004).
7) K. Sasaki et al., Nucl. Phys. A 998, 121737 (2020).

where Σ is the spin operator acting on a Dirac spinor
†
∗1
∗2
∗3
∗4
∗5

(b)

Codensed from the article in Phys. Rev. C 105, 044324(2022)
Department of Physics, Tohoku University
Graduate Program on Physics for the Universe, Tohoku University
Center for Mathematics and Physics, the Univertysi of Aizu
RIKEN Nishina Center
School of Physics and Microelectronics, Zhengzhou Univeristy- 36 -

Ⅱ-2. Nuclear Physics (Theory)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Microscopic collective inertial masses for nuclear reactions in thepresence of the nucleonic eﬀective mass†
K. Wen∗1 and T. Nakatsukasa∗1,∗2
A theoretical description of low-energy nuclear reactions with a solid microscopic foundation is still achallenging subject in nuclear physics. It may provide
us with a deep insight into the reaction mechanisms
and quantum dynamics of many-nucleon systems. Our
strategy is as follows. First, we ﬁnd a collective subspace spanned by a few selected collective canonicalvariables, which is decoupled from the intrinsic excitations. The collective subspace and collective variables
can be extracted using the adiabatic self-consistent collective coordinate (ASCC) method.1) The collective
subspace in the adiabatic regime is given by a seriesof time-even Slater determinants and generators of thecollective coordinates and momenta locally deﬁned foreach state. We apply the method to low-energy nuclear
reactions, to identify the optimal reaction path andcanonical variables. The self-consistently determinedcollective reaction path is requantized. The procedure
results in the reaction model= Euℓ (R),(1)

Jx [MeV-1h2]{}ℓ(ℓ + 1)d
1d−+
+ V (R) uℓ (R)dR 2M (R) dR
2J (R)

nuclei for the velocity-independent mean-ﬁeld potential. We also examined those of the cranking formula,which turned out to be almost identical to the ASCC
mass at R → ∞. However, this is not true in general. In particular, the nonlocal mean-ﬁeld potential
produces the eﬀective mass m∗ /m < 1. In this case,in order to guarantee the Galilean invariance of theenergy density functional, we need densities that are
time-odd with respect to the time-reversal transformation. The time-odd mean ﬁelds play important rolesin the time-dependent dynamics because the time-odd
densities are nonzero in general for the time-dependent
states. Since the ASCC equations are derived fromthe time-dependent mean-ﬁeld theory, they are able
to take into account the eﬀects of the time-odd meanﬁelds in calculations of the inertial masses. We havefound that the ASCC inertial masses reproduce thecorrect asymptotic values, whereas the cranking formula fails to do so.
Figure 1 shows the results for the moments of inertia J (R).
The velocity dependence
in the mean-ﬁeld
6
ASCC
Cranking
potential violates the local
Galilean invariance. The
Rigid body5
Point masscalculated
cranking moments
of inertia (dashed line)
are signiﬁcantly
smaller than the rigid-body value Jrig
4
(dotted line). They are also smaller than the point3
particle value µred R2 (dash-dot line) at large R. In
contrast,2 the ASCC calculation (solid)
includes the
α + 16O
residual eﬀects of the time-odd mean ﬁelds, which re1
store the local Galilean invariance, nicely reproducingµred R2 0at R > 7.5 fm. Near the equilibrium state
4.5
5
5.5
6
6.5
7
7.5
(R ∼ 5.5 fm),
it also
reproducestherigid-bodyvalue.

where R is the relative distance between the projectile and the target nuclei. The wave function for the
relative motion is given by ψ(R) = ul (R)Ylm (R̂)/R.
The key ingredients of the requantization procedure
are the potential V (R), the inertial mass parameterswith respect to the collective coordinates M (R), andthe rotational moment of inertia J (R) in Eq. (1). For
the nuclear reaction, the relative distance R between
two colliding nuclei should be properly chosen collective coordinates in the asymptotic region (R → ∞).
The corresponding inertial mass should be the reduced
mass µred = AP AT m/(AP +AT ), where AP (AT ) is themass number of the projectile (target) nucleus and m isthe bare nucleon mass. The moment of inertia J (R) in
Eq. (1) also has an asymptotic value, J (R) → µred R2
at R → ∞. Therefore, the theory can be tested byexamining its asymptotic limit. However, the inertial
masses in the interior region where two nuclei toucheach other are highly nontrivial. Thus, a microscopic
theory for calculating the mass over the entire reaction
path is necessary.
In our previous studies,2) we calculated the ASCC
inertial masses for the relative motion between two†∗1∗2

R [fm]18

Jx [MeV-1h2]

16
14
12
10
8
6

16O + 16O

4
2
0

5

5.5

6

6.5

7

7.5

8

8.5

R [fm]

Fig. 1. Rotational moments of inertia as a function of therelative distance R for 16 O+16 O. See text for details.

References
1) T. Nakatsukasa et al., Rev. Mod. Phys. 88, 045004(2016).
2) K. Wen et al., Phys. Rev. C 94, 054618 (2016); ibid. 96,
014610 (2017).

Condensed from the article in Phys. Rev. C 105, 034603(2022)
Center for Computational Sciences, University of Tsukuba
RIKEN Nishina Center- 37 -

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Gamow-Teller transitions in magic nuclei calculated based on the
charge-exchange subtracted second random phase approximation†
M. J. Yang,∗1 C. L. Bai,∗1 H. Sagawa,∗2,∗3 and H. Q. Zhang∗4experimental data, except for 90 Zr, in which the calculated peak height is approximately two times larger
than the experimental result. We examined the eﬀectof tensor terms of the SAMi-T EDF and found thatthe terms shift the main peaks downward by approximately 1 MeV in 48 Ca, 132 Sn, and 208 Pb; however,they hardly aﬀect 90 Zr. The quenching factor has increased slightly; however these values with the tensor
interactions are still about a half of the experimental
quenching factors. We explored the possibility whether
the tensor force with diﬀerent strengths further enhances the quenching factor of the GT strength. To
this end, we adopt the T21, T44, and T55 EDFs fromthe TIJ family3) with diﬀerent values of of the tensor
terms. We realized that none of these three parameter90
Zr
sets well described the strength distributions. How12
90
12
EXP
ever, Zrthe T55 EDF produces large quenching factors:
48
12
Ca SAMi-T w/o
EXP
EXP 25% for 90 Zr, 27% for 132 Sn, and 19%
30% for 48 Ca,
SAMi-T w/i
SAMi-T w/ow/o
SAMi-T w/o
208SAMi-T
SAMi-T w/i
SAMi-TIn
w/i208 Pb, the quenching factors are smaller,
Pb.
for
8
SAMi-T w/i
SAMi-T w/o
SAMi-T w/o
8
SAMi-T w/i
8 which is
SAMi-Tw/i
relatedto the insuﬃcient cutoﬀ energy of 2p2h conﬁgurations.
4
Further we studied the role of tensor interactions(b)4
4
in quenching with the parameter
sets, i.e., SGII +
(b)
(a)
Te1,
SGII
+
Te2,
and
SGII
+
Te3
keeping the cen0
0
5
10
15
20
25
25
tral
part
unchanged.
With
these
parametersets, we00
E (MeV)
0
5
10 x
15
20
25
0 found 5that the
10 tensor
15 interactions
20
25
signiﬁcantly
aﬀect
Ex(MeV)Ex(MeV)the strength distributions of GT peaks, i.e., strong ef9060
Zr
fect on the spreading of the strength distribution and
208
12
Pb
60
50
EXP
shift208ofthe excitation energy. Among the parameters,
50
132
Pb
w/o
Sn SAMi-TEXP
SGII+
Te1 best reproduces the GT strength distriSAMi-T w/i
50
SAMi-T w/o
40
SAMi-T
w/o
EXP
40
SAMi-T EXP
w/ibutionsinthe four nuclei. While the SGII + Te1 and
8
SAMi-T
w/i
SAMi-T w/o
SAMi-T
SAMi-Tw/ow/o40
SAMi-T
w/i
SAMi-T
SAMi-Tw/i
w/i
SGII
+
Te3
EDFs,
in which the strengths of the tripletSAMi-T w/o
30
30
SAMi-T w/o
SAMi-T term
w/i
SAMi-T w/i
odd
tensoraresigniﬁcantly diﬀerent even in the
30
20
sign,
producelargequenchingfactors similar to those420(b)20 of T55. In addition, as SGII is optimized excluding(d)10
J2 terms, we performed the calculations
in which the
10
(d)
(c)
10
2
00
terms
are
excluded
in
HF
and
SSRPA
for the SGII
J
25
00
10
55
10
1515
20 20
25 25
0
0 EDF. The calculations indicate that the exclusion of
(MeV)
EE
(MeV)
0
5
10 x x
15
20
0
5
10
15
20
25
Ex(MeV)Ex(MeV)
from the momentum dependent inJ2 terms originatedFig. 1. GT− strength distributions of 48 Ca [panel (a)], andteractions generates larger quenching factors, close to
208 60Pb [panel208(b)]calculated
withSAMi-Tby
RPA(dash
experiments. However, the systematical description ofPblines)
the strength distributions in the four nuclei has not im50 and SSRPA (solid lines) with or without tensor
terms. The red lines EXP
represent SAMi-T without tensor
proved much compared to those with the J2 terms. It is
SAMi-T w/o
40 labeled w/o,
SAMi-T
terms
andw/ithe blue lines represent SAMi-T
still a challenge to describe realistic strength distribuSAMi-T w/owith tensor terms
labeledw/i. Experimental data are
SAMi-Tw/itions and large quenching factors with Skyrme EDFs.
30

(c)
(a)
20

GT strength(MeV-1)

-1

-1

20

GT strength(MeV-1)

EXP
SAMi-T w/o
SAMi-T w/i
SAMi-T w/o
SAMi-T w/i

GT strength(MeV )

20

-1 -1
GT strength(MeV) )-1GT strength(MeV(a)

GT strength(MeV )EXP
SAMi-T w/o
SAMi-T w/i
SAMi-T w/o
SAMi-T w/i

GT strength(MeV) -1)
GT strength(MeV

We studied the Gamow-Teller (GT) transitions infour magic nuclei, i.e., 48 Ca, 90 Zr, 132 Sn, and 208 Pb
based on a self-consistent Hartree-Fock (HF) + subtracted second random phase approximation (SSRPA)
model with diﬀerent Skyrme energy density functionals (EDFs). The SSRPA model describes systematically and quantitatively the GT strength distribution
in the four nuclei better than the RPA model.
The results of SAMi-T1) with and without tensor
terms are shown in Fig. 1. Speciﬁcally, SGII2) and
SAMi-T EDFs well reproduce the strength distributions of the main GT peaks in terms of the excitation energy and peak height in comparison with thetaken from Ref. 4) for 48 Ca and Ref. 5) for 208 Pb.

(c)

†
∗1
∗2

20

∗3
∗4

References

20

Condensed from the article in Phys. Rev. C 106, 014219(2022)(d)10
College of Physics, Sichuan University
RIKEN Nishina Center
0Center 0for Mathematics
and5
10 Physics,
15 University
20 of Aizu
25
Ex(MeV)
China Institute of Atomic Energy

1) S. H. Shen et al., Phys. Rev. C 99, 034322 (2019).
2) C. L. Bai et al., Phys. Rev. C 83, 054316 (2011).
3) T. Lesinsky et al., Phys. Rev. C 76, 014312 (2008).
4) K. Yako et al., Phys. Rev. Lett. 103, 012503 (2009).
5) T. Wakasa et al., Phys. Rev. C 85, 064606 (2012).

- 38 -

Ⅱ-2. Nuclear Physics (Theory)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Indication of α clustering in the density proﬁles of 44, 52 Ti†
W. Horiuchi∗1,∗2,∗3,∗4 and N. Itagaki∗1,∗2
The standard nuclear structure is shell structure; however, α-cluster structure often appears in the ground andexcited states of light nuclei. Here, we discuss the αcluster structure in medium mass nuclei, 44 Ti and 52 Ti,
and show that the development of core+α structure canbe quantiﬁed in the density proﬁles near the nuclear surface using proton-nucleus elastic scattering.
In the present study, we examine two diﬀerent density
proﬁles. Shell- and α-cluster conﬁgurations are generated by utilizing the basis states of the antisymmetrized
quasi-cluster model (AQCM),1) which can describe boththe j-j coupling shell and α-cluster conﬁgurations in asingle scheme. The AQCM basis for the core (40 Ca or
48Ca) plus α cluster is expressed by the antisymmetrized
product of the core and α-cluster wave functions, with R
being their distance. The wave function of the core nucleus is constructed based on the multi-α cluster modelat the zero-distance limit, corresponding to the N = 20
closure for 40 Ca and eight neutrons are additionally put
for the N = 28 closure of 48 Ca. The size parameters of
the core and α-cluster wave functions are taken as thesame for simplicity.
The shell-model wave functions for 44, 52 Ti are obtained by taking R → 0. The size parameter is ﬁxed toreproduce the measured charge radius of 44 Ti or 52 Ti.
We call this shell-model wave function as S-type.
For the α-cluster wave function, we determine the size
parameter to reproduce the measured charge radius of
the core nucleus and set the R value to reproduce thecharge radius of 44 Ti or 52 Ti. We call this α-cluster wave
function as C-type. The determined R value is large(2.85 fm) for 44 Ti, indicating a well-developed α-cluster
structure. The charge radius of 52 Ti is not known. However, to understand the role of excess neutrons, we assume R = 3 fm for 52 Ti, which is comparable to that of44
Ti.
Although both S- and C-types reproduce the charge
radius data, we discover that α clustering signiﬁcantly
changes the density proﬁles near the surface. To
quantify these changes, we evaluate the nuclear “diffuseness,”2) which is practically obtained by a twoparameter Fermi function, ρ0 /{1+exp[(r−R̄)/a]}, where
the radius (R̄) and diﬀuseness (a) parameters are determined by the least-square ﬁtting with the obtained
one-body density. The a values for S- and C-types are
0.56 fm and 0.63 fm for 44 Ti and 0.58 fm and 0.61 fm for
52
Ti, respectively. The α clustering signiﬁcantly changes
†
∗1
∗2
∗3
∗4

Condensed from the article in Phys. Rev. C 106, 044330(2022)
Department of Physics, Osaka Metropolitan University
Nambu Yoichiro Institute of Theoretial and Experimental
Physics, Osaka Metropolitan University
RIKEN Nishina Center
Department of Physics, Hokkaido University- 39 -

the nuclear surface diﬀuseness, especially for 44 Ti, owing
to the occupation of the diﬀused low-angular momentum
orbit, i.e., 1p orbit. For 52 Ti, the diﬀerence between Sand C-types is less signiﬁcant that of 44 Ti because theshell-model conﬁguration (1p3/2 )4 already has a diﬀused
nuclear surface.
We show that this diﬀerence can be detected by measuring proton-nucleus elastic scattering at intermediate
energies. The proton-nucleus diﬀerential elastic scattering cross sections are calculated by the optical-limit
approximation in the Glauber model. Inputs to the reaction model are one-body density distributions and proﬁlefunction. By using the standard proﬁle function, we conﬁrm that the theory reproduces the experimental crosssections for 40 Ca and 48 Ca using the wave functions obtained by the AQCM approach without introducing any
adjustable parameter.
Figure 1 plots the proton-nucleus diﬀerential elastic
scattering cross sections at 320 MeV/nucleon at aroundthe ﬁrst peak position, where the diﬀerence of the nuclear diﬀuseness is well reﬂected.2) For 44 Ti, we see thatthe diﬀerence between the S- and C-type cross sections
is large, considering that the uncertainties of the experimental proton-40 Ca cross sections at around the ﬁrst
peak position is only ≈4%.3) The diﬀerence is smaller
for 52 Ti, but it is signiﬁcant.

Fig. 1. Proton-44, 52 Ti diﬀerential elastic scattering cross sections at 320 MeV/nucleon for scattering angles near theﬁrst peak position.

In summary, we have investigated the density proﬁlesof 44 Ti and 52 Ti with the shell and α-cluster conﬁgurations and found that these two aspects can be distinguished by measuring the proton-nucleus diﬀerential
elastic scattering cross sections up to the ﬁrst peak position.
References
1) N. Itagaki et al., Phys. Rev. C 71, 064307 (2005).
2) S. Hatakeyama et al., Phys. Rev. C 97, 054607 (2018).
3) J. J. Kelly et al., Phys. Rev. C 44, 2602 (1991).

Ⅱ-2. Nuclear Physics (Theory)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Enhanced moments of inertia for rotation in neutron-rich nuclei†
K. Yoshida∗1

†
∗1

MeV-1

120

120

SkM*

Proton number

100

100

80

80

60

60

40

40

20

20

0
120

0

Exp.

100

Proton number

Nuclear rotational motion emerges due to the spontaneous breaking of rotational symmetry. As steppingaway from the magic numbers, the ﬁrst I π = 2+ state
becomes lower in energy: The collective mode of excitation changes its character from vibration to rotation
as the deformation develops.
Recently, various spectroscopic studies have been
conducted to explore unique structures in neutron-rich+nuclei. The excitation energy of the 2+
1 state, E(21 ),is often among the ﬁrst quantities accessible in experiments and systematic measurements have revealed theevolution of the shell structure. Besides the change ofthe shell structure associated with the onset of deformation, the E(2+1 ) value may provide rich information
on exotic nuclei. A signiﬁcant lowering of E(2+1 ), observed in a near-drip-line nucleus 40 Mg, could be asignal of new physics in drip-line nuclei,1) as the theoretical calculations have predicted that the magnitudeof deformation is not enhanced in 40 Mg compared to
the Mg isotopes with fewer neutrons.2)
There are 657 even-even nuclei with known E(2+1 ).
In the present study, I limit the scope by excluding
the very light nuclei (Z < 10), for which mean-ﬁeld
theory is least justiﬁed. This eliminates 22 nuclei. The
experimental data evaluated as 3/E(2+1 ) for 635 nuclei
are displayed in Fig. 1 as ‘Exp.’ There is no collective
rotation in spherical nuclei where the MoI is zero. I
deﬁned the spherical nuclei if the calculated MoI wasless than 0.1 MeV−1 . An additional 273 nuclei havebeen eliminated for that reason, leaving 362 nuclei inthe present analysis.
To quantitatively measure the theoretical accuracy,
I compared theory and experiment, and examined thestatistical properties of the quantity R = Jth /Jexp .
Here, Jth and Jexp are the theoretical and experimental MoI. For the SkM* functional, the average isR̄ = 1.02. Here, the Yamagami-Shimizu-Nakatsukasa
pairing functional3) was adopted. When excluding the
weakly deformed nuclei with the deformation parameter β < 0.1, R̄ = 1.07 for 332 data. Therefore, thepresent model overestimates the MoI by about 10%.
This analysis indicates that the 2+
1 state is mostly governed by the rotational MoI of the ground state, andthe self-consistent cranking model describes the MoI
surprisingly well for nuclei with a ﬁnite β value.
I investigate the MoI of neutron-rich nuclei, and discussed the unique features near the drip line. A striking feature observed in the result shown in Fig. 1 isthat the deformation is strong in the neutron-rich lanthanide nuclei around N = 100 and the MoI is large

80
60
40
20
0

0

20

40

60

80

100

120

140

Neutron number

160

180

Fig. 1. Calculated moments of inertia J for the SkM* functional. The experimental data are taken from NNDC,
which is evaluated as 3/E(2+1 ).

accordingly. Furthermore, the MoI in nuclei near the
drip line is comparable to that of heavy actinide nuclei, despite a mass number diﬀerence of about 40. The
MoI in the lanthanides with N ∼ 150 is about twiceas large as that in the N ∼ 100 region, although thedeformation of protons is almost the same. Because
the neutrons are spatially extended, β of neutrons andmatter are both smaller than those in the N ∼ 100 region, which is against a simple perspective for a large
MoI. The density dependence of a pairing functional
employed in the calculation is the origin of this uniquefeature near the drip line, and that weak binding plays
a minor role.
References
1) H. L. Crawford et al., Phy. Rev. Lett. 122, 052501(2019).
2) J. Terasaki et al., Nucl. Phys. A 621, 706 (1997).
3) M. Yamagami et al., Phys. Rev. C 80, 064301 (2009).

Condensed from the article in Phys. Lett. B 834, 137458(2022)
Research Center for Nuclear Physics, Osaka University- 40 -

Ⅱ-2. Nuclear Physics (Theory)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Does the second-order operator in the adiabatic expansion contributeto the collective mass?
K. Sato∗1,∗2
The adiabatic self-consistent collective coordinate(ASCC) method1) is a practical method for describing
large-amplitude collective motion in atomic nuclei withsuperﬂuidity and an advanced version of the adiabatictime-dependent Hartree-Fock-Bogoliubov (HFB) theory. According to the generalized Thouless theorem,
the state vector in the ASCC theory can be written in
the form

We consider the case where the pairing correlation
is not taken into account, and the Hamiltonian does
not include the three-body interaction. Then, we shallshow that the second-order collective operator Q̂(2)does not directly contribute to the collective mass if
the second-order canonical-variable condition⟨ϕ(q)|[Q̂(1) , Q̂(2) ]|ϕ(q)⟩ = 0

is imposed.2,3) Noting that Q̂(2) is written in terms of
A-terms only and that the Hamiltonian can be written
in terms of A-terms, B-terms, and normally ordered
quartic terms, one can easily see that|ϕ(q, p)⟩ = eiĜ(q,p) |ϕ(q)⟩,where Ĝ(q, p) is a linear combination of the a† a† and aa
terms. We shall call the a† a† and aa terms as A-terms,
and the a† a and aa† terms as B-terms. Recently, theASCC theory including a second-order collective operator has been proposed.2) There, Ĝ(q, p) is expandedas1Ĝ(q, p) = pQ̂(1) (q) + p2 Q̂(2) (q).
2

⟨ϕ(q)|[Ĥ, iQ̂(2) ]|ϕ(q)⟩ = ⟨ϕ(q)|[ĤA , iQ̂(2) ]|ϕ(q)⟩. (4)Here, ĤA denotes the A-part of Ĥ.
From the moving-frame Hartree-Fock equation, we
obtain(1)

ĤA = ∂q V Q̂(1) .
⟨ϕ(q)|[Ĥ, iQ̂(2) ]|ϕ(q)⟩= i∂q V ⟨ϕ(q)|[Q̂(1) , Q̂(2) ]|ϕ(q)⟩ = 0

∗2

(6)

if the second-order canonical-variable condition in
Eq. (3) is met. Then, the inertial mass B(q) is
B(q) = −⟨ϕ(q)|[[Ĥ, Q̂(1) ], Q̂(1) ]|ϕ(q)⟩.

(7)

The second-order collective operator Q̂(2) does not contribute to the inertial mass directly, but it can contribute only through the equations of motion. Q̂(2)contributes to the ﬁrst- and second-order movingframe equations of motion, which may aﬀect the statevector |ϕ(q)⟩.
Here, we have concentrated on the case without thepairing correlation. When the pairing correlation istaken into account, the Q̂(2) term in the inertial massin Eq. (2) does not vanish even if the condition in
Eq. (3) is imposed. Before ending this report, we add
one remark. It is not trivial whether one should/can
include the second-order canonical-variable condition
in Eq. (3) in the set of fundamental equations of the
ASCC theory. If it is imposed in addition to the ﬁrstorder canonical-variable conditions, there may be too
many conditions to determine the unknown quantities,
and the problem may be overdetermined. This point
will be investigated and reported in a future publication.

(2)

It is worth mentioning that the second term on theright-hand side gives a contribution of the same orderas the ﬁrst term.
The fundamental equations in the ASCC theory consist of the moving-frame HFB and quasiparticle random phase approximation (QRPA) equations and thecanonical-variable conditions, which are derived fromthe invariance principle of the Schrödinger equationand the canonicity conditions, respectively. The former is the equation of motion, and the latter the conditions for the collective variables to be canonical. In theconventional ASCC theory, only the canonical-variableconditions of O(1) and O(p) have been taken into account, while the equations of motion up to O(p2 ) aresolved to determine the state vector and collective operators, from which the collective Hamiltonian is calculated. In Ref. 3), the ASCC theory including thesecond-order collective operator Q̂(2) was successfully
applied to the Lipkin model, and it was shown thatthe inclusion of Q̂(2) improves the agreement with theexact solution.
∗1(5)

By substituting Eq. (5) into Eq. (4), we obtainIn the conventional ASCC theory, only the ﬁrst-ordercollective operator Q̂(1) is included. However, as shown
in Refs. 2) and 3), the second-order collective operator
Q̂(2) is involved in the moving-frame equations of motion. Moreover, Q̂(2) contributes to the collective massas
B(q) = −⟨ϕ(q)|[[Ĥ, Q̂(1) ], Q̂(1) ]|ϕ(q)⟩+⟨ϕ(q)|[Ĥ, iQ̂(2) ]|ϕ(q)⟩.

(3)

References
1) M. Matsuo et al., Prog. Theor. Phys. 103, 959 (2000).
2) K. Sato, Prog. Theor. Exp. Phys. 2018, 103D01 (2018).
3) K. Sato, Prog. Theor. Exp. Phys. 2017, 033D01 (2017).

Faculty of Education, Kochi University
RIKEN Nishina Center- 41 -

3. Nuclear Data

Ⅱ-3. Nuclear Data
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

EXFOR compilation of RIBF data in 2022
S. Shin,∗1 S. Watanabe,∗1 M. Kimura,∗2,∗3 M. Aikawa,∗2,∗3 and N. Otuka∗4,∗3
Nuclear databases are crucial for providing the best
estimates of nuclear reactions to a wide range of data
users in various scientiﬁc and related ﬁelds. Amongthem, nuclear reaction data support the most important aspects of nuclear technology (nuclear power generation, nuclear fuel cycle, environmental monitoring,
dosimetry, radiation safety, radioisotope production,
radiation therapy, medical diagnosis, etc.) and science(nuclear physics, nuclear chemistry, geophysics, space
physics, etc.).
The EXFOR library (EXchange FORmat for experimental nuclear reaction data) is the largest and mostglobally used publicly available database.1) It is maintained by the International Network of Nuclear Reaction Data Centers (NRDC) under the auspices of theInternational Atomic Energy Agency (IAEA).2) The
scope of the EXFOR library covers a wide range of
nuclear reactions such as neutron-induced, chargedparticle, and photon-induced reactions.
The Hokkaido University Nuclear Reaction Data
Center (JCPRG)3) was established in 1973 and joined
NRDC in 1975 as the ﬁrst member from Asian countries. The JCPRG is responsible for compiling nuclear
reaction data with charged particles and photons measured at Japanese facilities,4) and its contribution to
the EXFOR database amounts to approximately 10%of the total database. The database compilation process begins with scanning of peer-reviewed journal papers published within the scope of EXFOR. Subsequently selected papers are assigned to unique entry
numbers and entered into the EXFOR library, where
the editorial progress can be monitored. Bibliographic
information, experimental equipment, physical quantities measured, numerical data measured, and error
information are extracted and entered into a single EXFOR entry. During this process, we communicate withthe authors, asking questions regarding the content of
their paper, and requesting numerical data.
Aiming to increase the availability of RIBF data,
JCPRG has been compiling data obtained from RIBF
since 2010 in cooperation with the RIKEN Nishina
Center. The new EXFOR data related to RIBF experiment are as follows. We have compiled 40 new papers and revised 3 old entries, of which 17 were fromRIKEN; 17 new papers. We can access these data
based on the entry numbers presented in Table 1.
Collaboration with RIKEN has aided in the establishment of an eﬃcient procedure for compilation.
Much of the RIKEN data was compiled soon after the
∗1
∗2
∗3
∗4

publication of the papers, allowing for smooth accessby end users. We are also grateful to the authors of the
RIKEN papers who have provided us with numerical
data. This has greatly helped to improve the accuracy
and quality of the database.
Table 1. Entry numbers with references compiled fromRIBF data in 2022.

New

Total

E26205)
E26858)
E269311)
E270314)
E271217)
E272220)

Entries
E26596)
E26879)
E269712)
E270415)
E271318)
E272321)17

E26827)
E268910)
E269813)
E270516)
E271519)

We would like to take this opportunity to express
our thanks 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) IAEA
Nuclear
Data
Services,
https://www-nds.iaea.org/ .
3) Hokkaido University Nuclear Reaction Data Centre,
https://www.jcprg.org/ .
4) M. Kimura, AAPPS Bulletin 28, 24 (2018).
5) S. Wimmer et al., Phys. Lett. B 785, 441 (2018).
6) A. Frotscher et al., Phys. Rev. Lett. 125, 012501(2020).
7) Z. Tsoodolés et al., Appl. Radiat. Isot 168, 109448(2021).
8) H. Suzuki et al., Phys. Rev. C 102, 064615 (2020).
9) L. Yang et al., Phys. Lett. B 813, 136045 (2021).
10) Z. H. Yang et al., Phys. Rev. Lett. 126, 082501 (2021).
11) M. Aikawa et al., Nucl. Instrum. Methods Phys. Res.
B 498, 23 (2021).
12) D. Ichinkhorloo et al., Nucl. Instrum. Methods Phys.
Res. B 499, 46 (2021).
13) M. M. Juhasz et al., Phys. Lett. B 814, 136108 (2021).
14) M. Sakaguchi et al., Appl. Radiat. Isot 176, 109826(2021).
15) M. M. Juhasz et al., Phys. Rev. C 103, 064308 (2021).
16) D. Bazin et al., Phys. Rev. C 103, 064318 (2021).
17) H. Suzuki et al., Nucl. Instrum. Methods Phys. Res. B
317, 756 (2013).
18) F. Browne et al., Phys. Rev. Lett. 126, 252501 (2021).
19) M. Aikawa et al., Nucl. Instrum. Methods Phys. Res.
B 508, 29 (2021).
20) M. Aikawa et al., Nucl. Instrum. Methods Phys. Res.
B 515, 1 (2022).
21) K. Sugihara et al., Nucl. Instrum. Methods Phys. Res.
B 512, 102 (2022).

Graduate School of Science, Hokkaido University
Faculty of Science, Hokkaido University
RIKEN Nishina Center
Nuclear Data Section, International Atomic Energy Agency- 43 -

Ⅱ-3. Nuclear Data

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Measurement of isotopic production cross section on 99 Tc via protonand deuteron-induced reactions
R. Matsumura,∗1,∗2 H. Otsu,∗1 H. Wang,∗3 H. Sakurai,∗1 D. Nishimura,∗4 H. Takahashi,∗4 S. Takeshige,∗5
M. Tanaka,∗1 and Y. Togano∗1,∗5 for the RIBF-TM2021 Collaboration
resolution was 0.80%, not achieving even 3σ separation.
This is probably because the integration time of the
F11IC5) Shaping Amp. was unintentionally adjusted to
be too short. Although the identiﬁcation resolution is
insuﬃcient compared to the previous experiments, theyield can be counted up with the superposition of 2-D
Gaussian functions.
Moreover, the Ru isotopes from the 99 Tc beam arescarcely observed in the region indicated by the dashedline in Fig. 1. It was conﬁrmed that the Ru and Tc
isotopes with large pulse heights were overﬂowing insome or all of the ADCs with 6 channel readout. The
number of overﬂowed channels causes a diﬀerence in thepeak position of each isotope in the A/Q spectrum. In
Fig. 2, the A/Q spectrum is plotted for that overﬂow
bit information. The peaks indicated in the blue curve
are almost consistent with the unique A/Q of the Tc
isotopes. Whereas the red curve is considered to be
the sum of both responses because it has a peak inthe middle of each A/Q of Tc and Ru. We plan todecompose the red curve into each response from thestrictly deﬁned A/Q peak positions.
300

CountsIn order to evaluate the reactions of the long-lived
ﬁssion products (LLFPs) with neutron, we have measured systematically the proton- and deuteron-induced
cross sections for 90 Sr,1) 137 Cs,1) 93 Zr,2) 107 Pd,3) etc.
As a next step, we started a study on 99 Tc, which is
known to be one of the LLFPs.
A secondary beam including 99m Tc was produced by
the in-ﬂight ﬁssion of 238 U at 345 MeV/nucleon on a
3-mm-thick 9 Be target, selected and identiﬁed eventby-event using the TOF-Bρ-∆E method4) in BigRIPS.
It also included 99m Tc (T1/2 = 6 h), which is indistinguishable by the same method, was irradiated to a
3-mm-thick Al plate and studied for the production ratio by in-ﬂight ﬁssion using the Ge detector. Cocktail
beams of 99 Tc and 99m Tc at 114 MeV/nucleon werebombarded with CH2 , CD2 , and C reaction targets
placed at the entrance of ZD spectrometer (ZDS). The
residual nuclei produced in the reactions were identiﬁed in ZDS. Since the momentum acceptance of ZDS islimited to ±3%, the measurement was conducted using
5 diﬀerent momentum settings (∆ (Bρ) /Bρ = −9, −6,−3, 0, and +3%) for each target to accept a wide rangeof the mass-to-charge ratio A/Q.
Figure 1 shows particle identiﬁcation of residual nuclei was realized by combining A/Q and atomic numberZ, derived from the measured information in ZDS. The
A/Q (relative RMS) resolution was 0.20%, which corresponds to 5.4σ separation. On the other hand, the Z

Tc

200
100

Atomic number ZF11

45
44

Ru

43

Tc

42

Mo

41

Nb

40

Zr

39

Y

38
2.1

2.15

2.2
2.25
2.3
Mass-to-charge ratio A/QF9-F11

0
2.1

10

∗2
∗3
∗4
∗5

2.15

2.2

2.25

2.3

2.35

Mass-to-charge ratio A/QF9-F11

Fig. 2. A/Q spectra showing the dashed line region in Fig. 1,
these are imposed overﬂow bit = 5, 6 for red curve and
1 for blue curve.

1

We have started a new study of proton- and deuteroninduced cross sections on 99 Tc. After the analysis
method is ﬁnalized, the other remaining targets will
be analyzed.

10−1
2.35

References

Fig. 1. Particle identiﬁcations of residual nuclei were
produced in reactions with the CH2 target at the∆ (Bρ) /Bρ = −6% setting on ZDS.
∗1

Ru+Tc

RIKEN Nishina Center
Department of Physics, Saitama University
RIKEN Cluster for Pioneering Research
Department of Natural Sciences, Tokyo City University
Department of Physics, Rikkyo University- 44 -

1) H. Wang et al., Phys. Lett. B 754, 104 (2016).
2) S. Kawase et al., Prog. Theor. Exp. Phys. 2017, 093D03(2017).
3) H. Wang et al., Prog. Theor. Exp. Phys. 2017, 021D01(2017).
4) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).
5) K. Kimura et al., Nucl. Instrum. Methods Phys. Res. A
538, 608 (2005).

Ⅱ-3. Nuclear Data
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Generating scattering data using Gaussian process regression†
S. Watanabe,∗1 F. Minato,∗2,∗3 M. Kimura,∗4 N. Iwamoto,∗2 and S. Yoshida∗5
Recently, several studies1,2) have employed machinelearning algorithms to improve the accuracy of nuclear data evaluation and reduce the production cost.
Herein, we introduce a framework which combines
Gaussian process regression (GPR) with a nuclear reaction model code, i.e., ‘CCONE’.3,4) The framework
determines model parameters required by CCONE toreproduce and predict nuclear reaction data.
Figures 1 and 2 demonstrate how the proposed
framework works. In this example, we used the experimental data of neutron elastic scattering on 54 Fe
at incident energies of E = 6, 10, 15, and 17 MeV as
input.5) In the ﬁrst step, by combining CCONE andBayesian optimization with the Gaussian process (BOGP), we optimize the depth of the real part of the opti0(E), to reproduce
cal potential, which is denoted by vR0these data. The obtained optimal values of vR(E) ateach energy is plotted by open circles in Fig. 1.

Expt.

103

Prediction
Prediction updated byadditional input

d/d [mb/sr]

102
101

7MeV

100

10-1

12MeV

10-2
10-3
10-4
0

26MeV
54Fe(n,n)
30

×10-2
×10-4

60
90
120
150
scattering angle [degrees]

180

Fig. 2. Predicted and observed angular distributions of
54
Fe(n, n) at the incident energies of E = 7, 12, and
26 MeV.

52.5
50.0

0
Then, using CCONE and the predicted value of vR(E),
our framework predicts unknown cross sections. Figure 2 shows the comparison of the prediction resultsfor E = 7, 12, and 26 MeV with the actual experimental data. The framework works quite eﬀectively
to predict data at E = 7 and 12 MeV, which correspond to the interpolation of the known data. Even in
the case of the extrapolation of the known data, i.e.,
E = 26 MeV, it can perform a plausible prediction.
This framework can investigate how new experimental data improve prediction. Herein, we add a newdata set at E = 20 MeV, and calculate the optimal
0vR(E) at this energy, as denoted by the ﬁlled circle inFig. 1. With this additional input, GPR can enhance0(E), as denoted by the dashed line
the prediction of vR0(E), thewith a shadowed area. With this enhanced vRcross section at E = 26 MeV is calculated as plotted
as a dotted line in Fig. 2, where we see considerable
improvement in backward angles.
The development of this framework is in progress,
and we expect that it will generate accurate nuclear
reaction databases enhanced with a large amount ofexperimental data produced at RIBF.

(MeV)

47.5
45.0
Input
42.5

Additional input

40.0

Prediction

37.5

Prediction updated byadditional input

35.0

0

10

20

30

Energy (MeV)
0
Fig. 1. Open circles show the optimal values of vR(E) atE = 6, 10, 15 and 17 MeV obtained by BO-GP. With0
these input, GPR predicts vR(E) as shown by solidline with shadowed area. With additional input at
E = 20 MeV denoted by ﬁlled circle, GPR updates
the prediction as shown by dotted line with shadowedarea.

In the second step, using optimal values as inputs,
0(E) as a function of E is predicted by GPR, as devR
noted by the solid line with a shadowed area in Fig. 1.
†
∗1
∗2
∗3
∗4
∗5

References
1) A. E. Lovell et al., J. Phys. G 47, 114001 (2020).
2) H. Iwamoto et al., J. Nucl. Sci. Technol. 57, 932 (2020).
3) S. Watanabe et al., J. Nucl. Sci. Technol. 59, 1399
(2022).
4) S. Watanabe et al., Eur. Phys. J. Conf. Ser. (in press).
5) All experimental data are collected from EXFOR
database.

Condensed from the articles in J. Nucl. Sci. Technol. 59,
1399 (2022)
Department of Physics, Hokkaido University
Nuclear Data Center, Japan Atomic Energy Agency
Department of Physics, Kyushu University
RIKEN Nishina Center
Institute for Promotion of Higher Academic Education, Utsunomiya University- 45 -

4. Hadron Physics

Ⅱ-4. Hadron Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Transverse single spin asymmetry for forward neutron production√in polarized p + p collisions at s = 510 GeV
M. H. Kim∗1 for the RHICf Collaboration∗1

RHICf Preliminary

AN

Transverse single spin asymmetry (AN ) is deﬁned
by a left-right cross-section asymmetry with respect tothe beam polarization. In high-energy polarized p + p
collisions, AN of the forward (pseudorapidity η > 6)
particle is a unique observable for studying the spininvolved diﬀractive particle production mechanism.
AN for forward neutron production has been explained by the interference between the spin ﬂip (πexchange) and nonﬂip (a1 exchange) amplitudes witha nonzero phase shift. This π and a1 exchange model
predicted that the neutron AN would increase in magnitude with the transverse momentum (pT ) and explained the PHENIX data, which had been measured
with three diﬀerent collision energies, 62.4, 200, and
500 GeV.1) Recent
PHENIX results,2) which unfolded√
AN on pT at s = 200 GeV, were also in good agreement with the prediction of the π and a1 exchange
model. However, the π and a1 exchange model predicted the neutron AN only in the range of pT <0.4 GeV/c.
In June 2017, the RHICf experiment3) measured AN
for forward√ neutron production in polarized p + p collisions at s = 510 GeV by installing an electromagnetic
calorimeter,4) the RHICf detector, at the zero-degreearea of the STAR experiment at the Relativistic Heavy
Ion Collider. We measured the neutron AN over a
wider range of 0 < pT < 1 GeV/c to compare theresults with those of PHENIX and to test the π anda1 exchange model in the higher pT region. In this article, we report the preliminary results of the neutron
AN measured by the RHICf experiment.
Neutrons were separated from the photon background using the diﬀerence between their shower developments in the detector. Once the neutron candidates
were selected, Bayesian unfolding,5) which is available
in the RooUnfold library,6) was applied to estimate
the true longitudinal momentum fraction (xF ) and pT
distributions. AN could be calculated because unfolding was applied for events from both spin-up and spindown polarizations. Because ﬁnite photon and charged
hadron backgrounds were included in the neutron candidates, the AN backgrounds were subtracted by estimating their fractions. Refer to Ref. 7) for a moredetailed analysis procedure.
Figure 1 shows the preliminary results for the forward neutron AN as a function of pT . The systematic
uncertainties due to unfolding, the beam center calculation, polarization estimation, and background subtraction are included. In the range pT < 0.2 GeV/c,the values of the forward AN measured by RHICf arep↑ + p → n + X at s = 510 GeV (6 < η)
0

−0.1

−0.2

−0.3
0

0.28 < xF < 0.46
0.46 < xF < 0.64 RHICf at 510 GeV
0.64 < xF < 1.00
0.70 < xF < 0.85
PHENIX at 200 GeV
0.85 < xF < 1.00
0.2

0.4

0.6

0.8

1

p (GeV/c)T

Fig. 1. Forward neutron AN as a function of pT for diﬀerent
xF regions. The triangular and circular data points are
the RHICf and PHENIX results, respectively. The error bars indicated by lines and boxes correspond to thestatistical and systematic uncertainties, respectively.

consistent with those of PHENIX, even though the collision energies are diﬀerent. In the range xF > 0.46, AN
increases in magnitude with pT , even in the pT range
beyond where AN was calculated theoretically. Comparing the data points in xF < 0.46 and xF > 0.46,
there is a gap, which indicates that the neutron AN
is possibly dependent on xF , which has not been predicted.
In the preliminary results, large systematic uncertainties are assigned to background subtraction because an analysis of the front counter, which had been
installed in front of the RHICf detector to suppress the
charged hadron background, was not complete. However, the ﬁnal results will be released soon because thebackground study has been recently completed.
References
1) B. Z. Kopeliovich et al., Phys. Rev. D 84, 114012 (2011).
2) U. A. Acharya et al. (PHENIX Collaboration), Phys.
Rev. D 105, 032004 (2022).
3) RHICf Collaboration, arXiv:1409.4860v1.
4) K. Kawade et al., J. Instrum. 9, P03016 (2014).
5) G. D’Agostini, Nucl. Instrum. Methods Phys. Res. A
362, 487 (1995).
6) T. Adye, arXiv:1105.1160.
7) M. H. Kim for the RHICf Collaboration,
https://doi.org/10.5281/zenodo.7271694 .

RIKEN Nishina Center- 47 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

EIC activities in Japan
Y. Goto∗1 for the EIC-Japan GroupThe Electron-Ion Collider (EIC) is the highest priority future project in nuclear physics ﬁeld in the UnitedStates and is the world’s ﬁrst polarized electron + polarized proton and nuclei collider to be constructed at
Brookhaven National Laboratory (BNL).1) The EIC
User Group was established in 2016, with participantsfrom the U.S., Europe, Asia, and other regions numbering more than 1,300 members. In Japan, the EICJapan Group was established at approximately thesame time and has been very active. The EIC project
has now been authorized by the U.S. Department ofEnergy to begin the project execution phase, and thisyear we will prepare a Technical Design Report for the
next phase. The EIC-Japan group is also participatingin the design of the detector for the ePIC international
collaboration experiment to be conducted at the ﬁrst
collision point of the EIC.
In 2022, the EIC-Japan Group submitted a proposal to the Science Council of Japan’s “Future Science Promotion Initiative” as part of the “International High Energy Quantum Science Frontier: QCD
Research at Overseas Facilities.” The proposal aims
to promote QCD research to be developed at overseas
facilities, including high-density QCD at GSI-FAIR,
high-temperature QCD at CERN-LHC, nucleon andnuclear structure studies at BNL-EIC, and theoretical research and computational research of QCD. The
proposal was discussed and granted by the Japanese
Nuclear Physics Committee.
As part of our participation in the ePIC detector,
we aim to contribute to three subsystems. (1) For the
Zero-Degree Calorimeter (ZDC), we are leading the design (Fig. 1), simulation calculation, and performance
evaluation, and further evaluation is underway as thebasic design.2) The electromagnetic calorimeter technology in this design uses the tungsten/silicon detectorof ALICE-FoCal-E calorimeter,3) which is promoted
mainly by the University of Tsukuba group. Test beam
evaluations of the prototype detectors are conductedat CERN and Tohoku University’s ELPH facility, andradiation tolerance tests of the silicon detectors are
conducted at the RIKEN RANS neutron facility. (2)The construction of a barrel detector using AC-LGAD(Low-Gain Avalanche Detector), which has excellent
timing and position resolution, is intended to be conducted with the contribution of the EIC-Japan Group.
We plan to evaluate a test board shown in Fig. 2 thatcombines a sensor manufactured at BNL and a readout ASIC manufactured in France. In addition, we willdevelop a sensor with Hamamatsu Photonics K. K. in
Japan. Simulation calculations for design evaluationin combination with the ePIC detector are in progress.
(3) Discussion of contributions to the Free Streaming
DAQ system will proceed.

Fig. 2. A test board of the AC-LGAD.

Discussions are underway for cooperation with the
Asian region, particularly the South Korean and Taiwanese groups, which began in late 2022. In addition to the three subsystems mentioned above, we will
also deepen regional cooperation on projects led byother Asian groups. Cooperation between the nuclear
physics and high-energy physics ﬁelds will also be expanded and developed in the future.
References
1) R. A. Khalek et al., Nucl. Phys. A 1026, 122447 (2022).
2) S. Shimizu et al., in this report.
3) ALICE Collaboration, ALICE-PUBLIC-2019-005.

Fig. 1. A design of the ZDC.
∗1

RIKEN Nishina Center- 48 -

Ⅱ-4. Hadron Physics
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Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Impact studies for transverse spin measurements at the EIC†
R. Seidl∗10.0010 < x < 0.0022
1.0 < Q2 / GeV 2 < 3.2

0.1

A UT

A UT

A UT

0.0215 < x < 0.0464
1.0 < Q2 / GeV 2 < 3.2

0.1

0.05

0.1

0

0

0

−0.05

−0.1

−0.05

True A Col π+ 0.0 < PT < 4.0
True A Col π- 0.0 < PT < 4.0
Reco A Col π+ 0.0 < PT < 4.0

−0.1

0.2

0.4

0.6

0.8

0.4

0.6

0.8

∗1

0.6

A UT

−0.1
ep 5 GeV x 41 GeV

Reco A Col π+ 1.2 < PT < 4.0

0.4

0.6

−0.2

0.8

−0.2
0.2

0.4

0.6

0.8

0.2

0.4

0.6

0.8

z

z

Fig. 2. Expected uncertainties for positive pion Collins
asymmetries in three transverse momentum bins as afunction of momentum fraction z, in three example binsof DIS variables x and Q2 in 5 GeV × 41 GeV e-p collisions.

δd

gT

−0.05
−0.10
−0.15
−0.20
−0.30

0.4

A UT

0

−0.1

Reco A Col π+ 0.3 < PT < 1.2

0.1

z

−0.35

0.8

0.75 0.85 0.95 1.05
Gupta et al (2018)
Alexandrou et al (2019)
JAM20+EIC(ep) +EIC(ep + e3He)+ECCE(ep) +ECCE(ep + e3He)z

0.55 0.65 0.75 0.85 0.95 1.05

Fig. 1. Example of the positive (generated: black, reconstructed: green) and negative (generated: blue, reconstructed: purple) pion Collins asymmetries as a function of momentum fraction z, in three example bins of
DIS variables x and Q2 in 5 GeV × 41 GeV e-p collisions. For simplicity, transverse momentum was integrated over.
†

0

−0.25

0.2
z

0.1

Reco A Col π+ 0.0 < PT < 0.3

0.2154 < x < 0.4641
32 < Q2 / GeV 2 < 100

0.2

0

0.2

−0.2
0.2

z

0.0215 < x < 0.0464
1.0 < Q2 / GeV 2 < 3.2

0.2

0.1

−0.2

ep 5 GeV x 41 GeV−0.1

Reco A Col π- 0.0 < PT < 4.0

0.0010 < x < 0.0022
1.0 < Q2 / GeV 2 < 3.2

0.2

−0.1

0.2154 < x < 0.4641
32 < Q2 / GeV 2 < 100

0.2

0.05

ments can be evaluated, as shown in Fig. 2. These
expected uncertainties can then be fed into the aforementioned global ﬁts to extract the impact of the EIC
measurements on the transverse polarization of quarks
in the nucleon, its integrals the tensor charges, and theSivers function, as previously performed in Ref. 1). It
was found that the ECCE detector proposal fullﬁlls
the requirements of the Yellow Report2) well and theimpact on the transverse spin and momentum structure of the nucleon is immense. As example the impact on the uncertainties of the tensor charged for up
and down quarks is shown in Fig. 3 in comparison
to the current precision and the Lattice QCD predictions. Eventually, discrepancies between Lattice andmeasurements could hint at physics beyond the standard model once the phenomenological description is
suﬃciently improved.
A UT

The ECCE proposal was one of three proposals forthe project detector of the Electron Ion Collider to bebuilt at Brookhaven national laboratory. It has since
been chosen and forms the baseline of the ePIC collaboration that has been formed recently. One of the goalsof the EIC is the extraction of the three-dimensionaltransverse spin and momentum structure of the nucleon. These can generally be accessed via semiinclusive deeply inelastic scattering (SIDIS) events
where in addition to the scattered lepton also a ﬁnalstate hadron is detected and its transverse momentum
and azimuthal asymmetries are extracted. Within the
ECCE proposal several full detector simulations were
performed using geant4 and pythia6 as generators.
While transverse momentum dependence is reasonably
described in the generator, transverse spin eﬀects are
not included. Those were artiﬁcially included based on
global ﬁts of existing data by reweighting each event
according to these parameterizations. In doing so azimuthal single spin asymmetries such as the so-called
Sivers and Collins asymmetries could be generated andreconstructed after the full simulations.
An example is shown in Fig. 1 for the Collins asymmetry of charged pions in two kinematic example bins
as a function of the hadron fractional momentum z.
In the higher x bin, where x describes the momentum
fraction the struck parton carries, a sizeable asymmetry is visible for both charges. The reconstructed
asymmetries are able to reproduce these results rather
well, suggesting little smearing of all kinematic variables involved. Extrapolating these simulations to the
expected accumulated luminosities of 10 fb−1 and assigning discrepancies between generated and reconstructed asymmetries as maximal systematic uncertainties, the expected precision of the EIC measure-δuFig. 3. Expected impact on the tensor charges under inclusion of the expected ECCE uncertainties. The small
diﬀerences between Yellow Report and ECCE impact
values arise from the diﬀerent pseudo-data sets resulting is slightly diﬀerent central values.

References

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. A 1049, 168017 (2023)
RIKEN Nishina Center

1) L. Gamberg et al., Phys. Lett. B 816, 136255 (2021).
2) R. Abdul Khalek et al., arXiv:2103.05419.

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Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Zero degree calorimeter for the ePIC experiment
S. Shimizu∗1,∗2 for the EIC Japan group
The Electron Ion Collider (EIC) is the next collider
scheduled to be built at the Brookhaven National Laboratory in US. It collides electrons and protons or nuclei and will provide a powerful measure to examine
the structure of protons and nuclei. In 2022, a newcollaboration was formed, named ePIC, as an experiment at the interaction point IP6. The ePIC detector
will be a multi-purpose detector, with suites of detectors in the far-forward and far-backward regions of theion-beam direction.
The Zero Degree Calorimeter (ZDC) is one of the
far-forward detector systems. It is used to detect photons and neutrons coming from the interaction point.
The ZDC enables measurements for several key EIC
physics programs1) such as exclusive vector meson production in e + A collisions or spectator-neutron-taggede + d deep inelastic scattering. Its ﬁrst design wasconsidered for EIC in the previous report.2) It comprises a crystal calorimeter and three types of sampling
calorimeters.
The same ZDC design was adopted to the ePIC detector as a baseline ePIC ZDC design. In the ePIC
collaboration, a new software framework was developed and the ZDC design was migrated there. Figure 1
shows a schematic of the ePIC detector including the
ZDC.
A few details of the ZDC design are examined anddiscussed: material of the crystal calorimeter, radiation resistance of photon detectors, and placement of
the ZDC.
The material of the crystal calorimeter was studied
by simulation. Two materials were compared: LYSO
and PbWO4 , where the former has a >100 times higher
light yield but is more expensive with respect to thelatter. Considering the photon counting eﬀect, thecomparison showed no large diﬀerence in the cluster
ﬁnding eﬃciency. Worse energy resolution was observed for PbWO4 , but it is still acceptable for thephysics requirement of 20%. As far as the performanceof the calorimeter system is sustained as designed,
PbWO4 can be used for the ZDC crystal calorimeter.
The crystal calorimeter requires photon detectors
to detect light in the crystal, and avalanche photodiodes (APDs) are the ﬁrst candidate for the ZDC.
Hamamatsu APDs S8664-55 were irradiated at RANS,RIKEN Accelerator-driven compact Neutron Sources,
to test their radiation resistance. Following two daysof irradiation, the estimated dose on the APDs is 1012 –1013 neutrons/cm2 .a) All the irradiated APDs seem to
∗1
∗2
a)

Fig. 1. A schematic of the ePIC detector, observed from thedownstream of the ion beam line, as implemented in theePIC software framework. The ion beam goes from theleft side top to the right side bottom as indicated by thearrow. The large disks are calorimeter endcaps of theePIC main detector. The ZDC is the set of rectangularsolids at the bottom right. In the far-forward region,
only the ion beam line is shown.

lose their function. With the EIC operation for a thirdof a year, the EIC ZDC is expected to be exposed to
8 × 1012 neq /cm2 per year.3) The APDs do not have
suﬃcient radiation resistance for the EIC ZDC and another technology is needed.
The ePIC ZDC will be situated between the electron
and ion beam lines. Its placement was revised following consultations with experts in US. The ZDC has
a limited space to place the front-end system close to
the ZDC. Discussion on the readout system has started
and is ongoing.
In summary, the previously reported ZDC design isadopted to the ePIC detector and discussions on several aspects is ongoing for realization of the design.
The ZDC eﬀort is also in close contact with the ALICE
FoCal development,4) which had several test-beam experiments conducted in 2022, as the same techniquewill be used in ZDC sampling calorimeters.
References
1) R. A. Khalek et al., EIC Yellow Report, arXiv:2103.05419.
2) S. Shimizu et al., RIKEN Accel. Prog. Rep. 55, 47(2022).
3) V. Baturin, internal document.
4) ALICE collaboration,
ALICE-PUBLIC-2019-005,
https://cds.cern.ch/record/2696471 .

RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), IPNS, KEK
The dose estimation is based on the measurement using radioactivation of indium foils.

- 50 -

Ⅱ-4. Hadron Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Centrality dependence of charm and bottom quark suppressionin Au + Au collisions at RHIC†
T. Hachiya∗1,∗2 for the PHENIX Collaboration
Charm and bottom quarks, collectively referred asheavy ﬂavor, are a clean probe to study the propertiesof quark-gluon plasma (QGP) produced in high-energy
heavy-ion collisions. Because of their large mass, heavy
quarks are predominantly produced at the initial stageof the collisions. Once produced, heavy ﬂavors lose theirenergy as they propagate through the QGP. The energy loss of heavy quarks is expected to be suppressedby “dead cone” eﬀect, where gluon radiation caused bybremsstrahlung is suppressed at an angle smaller thanthe mass-to-energy ratio of the quark.1) Thus, energy
loss is expected to follow the mass ordering of quarks andgluons, ∆Eg > ∆Eu,d > ∆Ec > ∆Eb . The PHENIX experiment previously observed the diﬀerent suppression ofelectrons from charm and bottom hadron decays in min√imum bias Au + Au collisions at sN N = 200 GeV.2)
This article reports the centrality dependence of charmand bottom quark suppression measured at PHENIX.
Using the high-statistics dataset recorded in 2014 andthe updated p + p reference from 2015,3) the nuclear
modiﬁcation factor, RAA (a ratio of yields in Au + Au top + p after normalized by number of binary collisions) of
the charm and bottom electrons in four centrality classes(0–10, 10–20, 20–40 and 40–60%) of Au + Au collisions
can be measured with improved precision compared with
our previous results.2)
Heavy ﬂavor electrons are measured using the central
arm PHENIX detector. An inner silicon tracker, VTX,
measures the distance of closest approach of the electron
track, DCAT , to the collision vertex in the transverse
plane. Using the diﬀerent decay lengths of charm andbottom hadrons (cτ = 123 µm for D0 and 455 µm forB 0 ), electrons from these decays are statistically separated by the DCAT . The measured electron samples
contain not only heavy ﬂavors but background electrons.
The main background is photonic electrons which arephoton conversions and Dalitz decays of light neutralmesons. The background is mostly rejected by the analysis cut with the hit-pair on VTX as the electron pairs
from the photon conversions produce hits that are close
to each other. The remaining backgrounds are estimatedthrough the full GEANT detector simulation and subtracted from the measured electron samples. The electron samples are separated by the unfolding, which simultaneously ﬁts the transverse momentum pT spectrum
and DCAT distributions.
Figure 1 shows RAA in 0–10% central Au + Au collisions. The blue and green lines represent the bottomand charm electrons with 1-sigma uncertainty bands,

Fig. 1. RAA for charm and bottom electrons compared withthe theoretical models.

respectively. Signiﬁcant suppression is seen for both
charms and bottoms at high pT . Charm suppression isstronger than bottom suppression for pT = 2–5 GeV/c.
The result was compared with the models that expect amass ordering of energy loss in QGP. All models reproduce the data reasonably within large uncertainty.
The centrality dependence of the suppression is studied using the number of nucleon participants in the collision (Npart ). Figure 2 shows RAA vs Npart for three
diﬀerent pT intervals. There is no suppression for both
charms and bottoms in low pT . The mid-pT region showsa clear suppression of charm hadrons but no bottom suppression. The high-pT region shows an increasing suppression of both charms and bottoms.

Fig. 2. RAA charm and bottom electrons as a function of
Npart for three pT intervals.

In summary, PHENIX studied the centrality dependence of charm and bottom suppression. A clear diﬀerent suppression was observed at pT = 2.5 GeV/c. The
suppression pattern is consistent with the models that
expect mass ordering of energy loss.
References

†

∗1
∗2

Condensed from the article in arXiv:.2023.17058
Department of Mathematical and Physical Sciences, Nara
Women’s University
RIKEN Nishina Center

1) Y. L. Dokshitzer et al., Phys. Lett. B 519, 199 (2001).
2) A. Adare et al., Phys. Rev. C 93, 034904 (2016).
3) C. Aidala et al., Phys. Rev. D 99, 10.1103 (2019).

- 51 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Study of v2 depending on multiplicity with ZDC energy event
categorization
R. Takahama∗1,∗2 for the PHENIX Collaboration
The PHENIX experiment was operated at BNLRHIC, which collides heavy ions at relativistic energy
to create a hot state in a second. In this state, quarks
and gluons are deconﬁned, and this state is called
quark-gluon plasma (QGP) the collective motion of
QGP is known. In hydrodynamic models, the detailed
azimuthal correlation structure of emitted particles resulting from the collective motion is typically characterized by its Fourier components, known as the elliptic
ﬂow (v2 ).1)
In the past decade, some results have suggested
the possibility of QGP-like matter creation during extremely high multiplicity events in a lighter collisionsystem than that of heavy ions.3–7) However, the mechanism of that possibility has not been revealed. One
helpful fact is that the ridge structure and collective
motion are measured only in extremely high multiplicity events, where multiparton interactions become
more relevant.8)
The eﬀect of multiparton interactions in heavy ion
collision is of interest to us. Selecting events with thesame number of participating nucleons in the collision
is crucial to study the multiparton interaction eﬀect
because much more nucleons interact in heavy ion collisions than in proton-proton collisions. We can not directory measure the number of participating nucleons
because they change to new particles after interactions.
However, the number of spectator (not participated incollision) neutrons can be directory detected by thezero degree calorimeter (ZDC). In high-energy heavyion collisions, most of the spectator nucleons outside of
the overlap region are causally disconnected from thematter produced by the participating nucleons, so wemeasure the energy of spectator neutrons captured by
ZDC. We classify the events with the number of participating nucleons in the collision as in p + p collisionby selecting the events with the same energy measured
by ZDC, thus creating a simple situation to study multiparton collision. Furthermore, the multiplicity has awidth at some ZDC energy sum events. We assumed
that the eﬀect of the multiparton interaction makes
this width. If the multiparton interaction eﬀect is more
relevant, a larger multiplicity should be obtained fromevents with the same number of participating nucleons. Because v2 increases as a function of the numberof tracks in p + p collision,7) v2 will be larger in events
where the multiparton interaction eﬀect is more relevant. Analyzing v2 as a function of multiplicity at
the same energy in the ZDC detector can tell us if the∗1∗2

multiparton interaction eﬀect is worth consideration inheavy ion collision.
Our goal is to analyze v2 as a function of multiplicity using the ZDC energy sum event categorization in√
Au + Au collision data taken at sN N = 200 GeV in
the PHENIX experiment. Such an event categorization has never been used to analyze v2 , so we workedon the reaction plane angle calibration to make its distribution ﬂat. Figure 1 shows the reaction plane angle
distribution after calibration of the one of the eventclasses. A ﬁtting to these distributions with a straightline gave a χ2/ndf of approximately 1.0. We checked
the ﬂatness for all event classes for all runs and ﬁnallyconﬁrmed that the calibration had been done successfully. We are now at the stage of analyzing v2 as afunction of multiplicity using calibrated events. The
results will be published in the near future.
×

χ

χ

−

−

−

−

−

−

Fig. 1. Reaction plane angle distribution after calibrationin events whose the number of normalized FVTX tracks
is larger than 0.50 and less than 0.55. Left: with no
ZDCe event selection. Right: events in 900 < ZDCe <910.

References
1) S. Voloshin and Y. Zhang, Z. Phys. C 70, 665 (1996).
2) S. Chatrchyan et al. (CMS Collaboration), Phys. Lett.
B 719, 29 (2013).
3) V. Khachatryan et al. (CMS Collaboration), Phys. Rev.
Lett. 116, 172302 (2016).
4) A. Adare et al. (PHENIX Collaboration), Phys. Rev.
Lett. 114, 192301 (2015).
5) L. Adamczyk et al. (STAR Collaboration), Phys. Lett.
B 747, 265 (2015).
6) A. Adare et al. (PHENIX Collaboration), Phys. Rev.
Lett. 115, (2015).
7) V. Khachatryan et al. (CMS Collaboration), Phys. Lett.
B 765, (2017).
8) W. Li, Mod. Phys. Lett. A 27, 1230018 (2012).

RIKEN Nishina Center
Division of Nature Physics, Nara Women’s University- 52 -

Ⅱ-4. Hadron Physics
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Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Completion of Bus-Extender development for sPHENIX INTT
T. Hachiya,∗1,∗2 Y. Akiba,∗2 J. Bertaux,∗3 K. Fujiki,∗2,∗4 M. Fujiiwara,∗1 S. Hasegawa,∗1,∗5 M. Hata,∗1,∗2
H. Imai,∗2,∗4 M. Kano,∗1 T. Kato,∗2,∗4 T. Kondo,∗6 C. M. Kuo,∗7 R. S. Lu,∗8 I. Nakagawa,∗2 Y. Namimoto,∗1,∗2
R. Nouicer,∗9 G. Nukazuka,∗2 C. W. Shih,∗7 M. Shimomura,∗1 R. Shishikura,∗2,∗4 M. Stojanovic,∗3
Y. Sugiyama,∗1,∗2 R. Takahama,∗1,∗2 W. C. Tang,∗7 H. Tsujibata,∗1 M. Watanabe,∗1 and X. Wei∗3
sPHENIX is a second-generation experiment at Relativistic Heavy-Ion Collider. It is scheduled to start in
2023 to explore the properties of quark-gluon plasma.
The INTermediate Tracker, INTT,1) is a silicon strip
detector placed in a tight and conﬁned space near the
beam pipe. INTT measures more than 1000 particles
in a collision. Large amount of raw data is sent to thelater read-out electronics placed more than 1.1 m awayfrom INTT with a curving path for signal processing
at high speed. It is diﬃcult for commercial cables suchas ﬂex ﬂat cable and co-ax cable to satisfy all the requirements listed below. We developed a special data
cable namely “Bus Extender (BEX)” for INTT basedon ﬂexible printed circuits (FPC).
The requirements for BEX are: (1) length of 1.1 m,(2) high-density signal lines (128 lines/5 cm), (3) highspeed data transfer of 200 Mbps by LVDS with 100 Ω
diﬀerential impedance, (4) ﬂexibility, (5) mechanicalreliability, and (6) radiation hardness. We developed
BEX for ﬁve years to satisfy all the requirements. Instead of the standard polymide, liquid crystal polymer(LCP) was used for the substrate to reduce loss of signals transmitted at high speed. The design of BEX
was optimized by the printed circuit simulation. The
prototype BEX was made for testing. BEX consists offour metal layers including signal, power, and groundlayers laminated by glue. The uniformity of width forsignal lines is measured to be 122 ± 2 µm.
Using the prototype BEX, the electrical performanceis measured with S-parameters, diﬀerential impedance,and eye-diagram and compared with the simulation.
Figure 1 shows S-parameter for insertion (SDD21) andreturn loss (SDD11). The data and simulation arelabeled as “meas” and “em,” respectively. From thecomparison, the simulation successfully reproduced theoverall behavior of the data. The eye-diagram is often
used to visually inspect the margin of the signal pulse.
By comparing the mask (gray hexagonal shape) which
represents the minimum requirement of the margin,
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Fig. 1. Insertion and return loss.

the measured eye diagram satisﬁed the requirement asshown in Fig. 2. The diﬀerential impedance was estimated as 95 Ω by the time domain reﬂectometry. The
result is slightly lower than the requirement but acceptable.

Fig. 2. Eye-diagram.

Department of Mathematical and Physical Sciences, Nara
Women’s University
RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteCenter for High Energy and High Field Physics and Department of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory

The mechanical reliability was evaluated by the peeling and the thermal shock test using the FPC samples
with the same conﬁguration. The peel strength between the laminated two layers was measured by a tensile tester. The result was more than 16 N/cm and indicates BEX has suﬃcient strength. We also compared
the strength with radiation exposure by 5 k Gy and- 53 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 56 (2023)

found no change. This indicates that the impedanceof BEX was not changed by irradiation. The thermal
shock test aimed to check the long-term stability. BEX
was exposed with −15◦ C and 75◦ C for 30 min. with
5 min. interval. The rapid change in temperature puts
physical stress with expansion and contraction. The
electrical resistance of the signal line is increased if thesignal line is damaged. After 1000 thermal cycles thatare equivalent to 8 years of use, we found no resistancechange. These mechanical performances are detailed
in Ref. 2).
After the evaluation of the prototype, we performed
the mass production of 130 BEXs. The issue with low
yield rate was investigated and the tiny dust caused
mis-formation of lines.3) A visual inspection ﬁxture
was also developed to monitor the line formation during production. As a result, the mass production wascompleted with almost 100% yield. In summer 2022,
all the BEX was assembled to the INTT barrel. INTT
and BEX are ready for sPHENIX data taking in April
2023.
References
1) Conceptual design report of sPHENIX (2018).
2) T. Kondo et al., Trans. J. Inst. Electron. Packag. 15,
E21 (2022).
3) T. Hachiya et al., RIKEN Accel. Prog. Rep. 55, 98(2022).

2- 54 -

Ⅱ-4. Hadron Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of graphical user interface application for
sPHENIX-INTT LV system
M. Watanabe,∗4 Y. Akiba,∗1 J. Bertaux,∗2 K. Fujiki,∗1,∗3 M. Fujiiwara,∗4 T. Hachiya,∗1,∗4 S. Hasegawa,∗1,∗5
M. Hata,∗4 H. Imai,∗1,∗3 M. Kano,∗4 T. Kato,∗1,∗3 T. Kondo,∗6 C. Kuo,∗7 R.-S. Lu,∗8 I. Nakagawa,∗1
Y. Namimoto,∗1,∗4 R. Nouicer,∗9 G. Nukazuka,∗1 C. Shih,∗7 M. Shimomura,∗4 R. Shishikura,∗1,∗3
M. Stojanovic,∗2 Y. Sugiyama,∗4 R. Takahama,∗1,∗4 W.-C. Tang,∗7 H. Tsujibata,∗4 and X. Wei∗2
We create a Graphical User Interface (GUI) thatallows you to operate the Low Voltage (LV). A control panel based on the Graphic User Interface (GUI)application is under development to operate the LV
power for a Read Out Card (ROC), i.e., an electronics to read out from the INTermediate Tracker (INTT)
detector. The INTT is one of the three tracking detectors in the sPHENIX experiment, which is scheduled to go live in the spring of 2023. The ROC is amulti-functional circuit board and consists of as manyas 3000 surface mount components. Thus ROC requires a couple of diﬀerent voltages to distribute relevant voltage(s) to each component. There are 13 LV
distribution modules assigned to power 8 ROCs. Each
module occupies a single VME slot and supplies a preset voltage up to 10 output channels. Thus a single
ROC power is provided by the multiple distribution
modules with various voltage settings. The LV distribution module can be operated from a remote server(KEPServer1) ) and its output voltage and current canbe readout from the KEPServer. The GUI has beendeveloped using the commercial application called “Ignition Designer”2,3) which runs on an Ignition Gateway PC. The KEPServer and the Ignition Gateway
are linked to the OPC interoperability standard.
Shown in Fig. 1 is the main control panel of the LV
control GUI. It is still under development. The panel isdesigned to be operated in the interactively. Clickablebuttons are implemented to turn on/oﬀ all powers (11channels) for ROC-1 at once.
Only ﬁrst ROC(ROC1) has already been implemented in the image, but the plan is to introduce new
buttons for ROC2, ROC3 . . . ROC8. The black buttons on the left with numbers from 1 to 11 represents
the slot number of the LV distribution module. The
table on the right of the panel displays the history ofabnormalities. It shows the channel and the time. In
†
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Fig. 1. The main control panel of the INTT LV distribution
modules.

order to avoid the main control panel being too busy
with too many buttons and voltage/current displays,a “Detail” button is implemented on the bottom left
corner of the panel. A new pop-up panel, as shownin Fig. 2, appears on the screen by clicking the Detail
button.

Condensed from the article in Phys. Rev. Lett. 85, 1827
(2000)RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteDepartment of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory

Fig. 2. A new pop-up panel appears by clicking “Detail”
button on the main control panel.

This panel displays the latest current and voltage
values of each channel of a given ROC. Further development is planned to change the color of buttons to express the power on/oﬀ status of each channel following- 55 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 56 (2023)

the same color coordinate manner of the main control
panel. The green rectangles with SLOT number are
also implemented to function as interactive buttons,
allowing each channel to turn on/oﬀ independently.
This GUI is still under development, so we would liketo create buttons that can control other ROCs and
ROC detail screens in the future.
References
1) https://www.kepware.com/en-us/ .
2) https://docs.inductiveautomation.com/display/DOC80/
Welcome .
3) https://docs.inductiveautomation.com/display/DOC80/
Standard+Architecture .

2- 56 -

Ⅱ-4. Hadron Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Detection eﬃciency of sPHENIX-INTT by cosmic ray measurements
and its timing dependence
Y. Namimoto,∗1,∗4 Y. Akiba,∗1 J. Bertaux,∗2 K. Fujiki,∗1,∗3 M. Fujiiwara,∗4 T. Hachiya,∗1,∗4 S. Hasegawa,∗1,∗5
M. Hata,∗4 H. Imai,∗1,∗3 M. Kano,∗4 T. Kato,∗1,∗3 T. Kondo,∗6 C. M. Kuo,∗7 R.-S. Lu,∗8 I. Nakagawa,∗1
R. Nouicer,∗9 G. Nukazuka,∗1 C. W. Shih,∗7 M. Shimomura,∗4 R. Shishikura,∗1,∗3 M. Stojanovic,∗2
Y. Sugiyama,∗4 R. Takahama,∗1,∗4 W. C. Tang,∗7 H. Tsujibata,∗4 M. Watanabe,∗4 and X. Wei∗2
INTermediate Tracker (INTT) is one of the three
tracking detectors for the sPHENIX experiment, which
will be started in April 2023 at the Relativistic Heavy
Ion Collider (RHIC) in Brookhaven National Laboratory. It comprises 56 ladders, each comprising two silicon strip sensor modules. One module is divided into
26 cells, and each containing 128 readout strips.
To measure the detection eﬃciency of INTT, we
executed beam tests three times. Although the expected eﬃciency is approximately 100%, the observed
eﬃciency was 96.0 ± 0.5% as the result of the second beam test at Fermilab Test Beam Facility (FTBF)
in 2019.1) The RHIC beam bunches are synchronizedwith 9.4 MHz clock and so as INTT readout electronics. However, some hits can fall into possible signal processing glitch between subsequent beam clocks(BCO) because the FTBF beam is asynchronous to
the RHIC-BCO. To verify the hypothesis, we executed
the third beam test at the ELPH facility at Tohoku
Univ. in 2021. We upgraded the DAQ system froma nominal Window-based DAQ to a CAMAC-based
TDC for the timing measurement of INTT hits w.r.t.
the BCO. As a result of this test, we obtained an efﬁciency of 99.56 ± 0.06%.2) Unfortunately, the timing
dependence measurement was unsuccessful because we
discovered the beam rate exceeded the DAQ processing
speed limit, and recorded data were unreliable. Therefore we should measure the detection eﬃciency and the
BCO dependence in low beam rate conditions. The
best way is to repeat the measurement with cosmicrays.
For cosmic rays measurement, we put three INTT
ladders in a dark box, and two scintillation counters
are set above and below the box for external triggers(Fig. 1). The internal clock of the readout electronics
is used as BCO. We call the ladders from top to bottom L1, L2, and L3. CAMAC measured the ADC ofscintillation counters and BCO timing.
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Fig. 1. Setup for cosmic rays measurements.

The eﬃciency of L2 layer is deﬁned as Eq. (1). Errors were calculated by the binomial distribution.
L2 Eﬃciency =ΣN(L1hit ∩ L2hit ∩ L3hit )ΣN(L1hit ∩ L3hit )(1)

The observed detection eﬃciency is 99.54 ± 0.06%,
reproducing the 2021 beam test result, by requiring
some zenith angle range to be nearly vertical. Thenthese event samples were classiﬁed into 11 relative
phase categories w.r.t. BCO, and the eﬃciency in eachphase was evaluated as shown in Fig. 2.

Fig. 2. Detection eﬃciency of every BCO.
RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteCenter for High Energy and High Field Physics and Department of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory

In summary, we conﬁrmed that the detection eﬃciency of INTT exceeds 99%, and it has no dependence
on BCO.
References
1) A. Suzuki, Master thesis, Nara Women’s University(2019).
2) M. Morita, Master thesis, Nara Women’s University(2021).

- 57 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

MIP measurement for mass production of sPHENIX-INTT ladderwith a positron beam
Y. Sugiyama,∗4 Y. Akiba,∗1 J. Bertaux,∗2 K. Fujiki,∗1,∗3 M. Fujiiwara,∗4 T. Hachiya,∗1,∗4 S. Hasegawa,∗1,∗5
M. Hata,∗4 H. Imai,∗1,∗3 M. Kano,∗4 T. Kato,∗1,∗3 T. Kondo,∗6 C. M. Kuo,∗7 R. S. Lu,∗8 I. Nakagawa,∗1
Y. Namimoto,∗1,∗4 R. Nouicer,∗9 G. Nukazuka,∗1 C. W. Shih,∗7 M. Shimomura,∗4 R. Shishikura,∗1,∗3
M. Stojanovic,∗2 R. Takahama,∗1,∗4 W. C. Tang,∗7 H. Tsujibata,∗4 M. Watanabe,∗4 and X. Wei∗2
The sPHENIX experiment will start in 2023 at theRelativistic Heavy Ion Collider in Brookhaven National
Laboratory. Intermediate Tracker (INTT) is one of thethree tracking detectors used in the experiment, which
consists of 56 ladders of silicon strip detectors. A half
ladder is divided into 26 cells which consist of two typesof silicon sensors with diﬀerent strip lengths, and eachcell includes 128 read-out FPHX chips.1)
In 2021 at ELPH, Tohoku University, we performed
a test beam experiment to evaluate the performance ofmass production ladders.2) We used the γ-ray beamline
at the facility, and irradiated a positron beam with amomentum of about 1 GeV. Three halves of a ladderwere used, and two scintillators were installed upstream
and downstream of them, respectively.
We evaluated the performance of silicon sensor by detecting Minimum Ionizing Particles (MIP). The noisecontamination to the MIP region in the energy deposit
spectrum is crucial to achieve good signal-to-noise ratio. The FPHX read-out chip converts the height of thesignal generated by the sensor into a 3-bit ADC. As a
preparation of the signal AD conversion process, the 8bit DAC threshold values (called DAC value) are presetwith approximately 4 mV step. When the signal is processed, a corresponding DAC value is assigned and set
in a data stream as a 3-bit ADC data. The ADC value
relates to energy loss of a traversing charged particle. It
is important to observe the entire energy deposit spectrum with a good resolution though, it is not possible
by using the built-in 3-bit ADC of FPHX chip. A series of sequential measurements were executed to scanthrough the full DAC range by setting the DAC to cover
only narrow range but ﬁne pitch in one measurement.
In the data analysis, events which have too many hits
away from the beam spot were removed. Only hits ona single strip were analyzed. A hit with the highest
ADC value was excluded from the full ADC spectrum
reconstruction event samples because the hit could bean overﬂow value. We reconstructed ADC distribution
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteCenter for High Energy and High Field Physics and Department of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory- 58 -

of a cell in the upstream ladder obtained from 8 runs.
Then the distribution was normalized by the numberof entries in two overlapping bins, shown in Fig. 1(a).
Then we took the average over each overlapping bin,letting each ADC distributions of narrow region connect smoothly with the spectrum of adjacent region. It
was performed in order from the smallest ADC conﬁguration to obtain one energy deposit spectrum.

Fig. 1. (a) The ADC distribution obtained from 8 runs bynormalizing entries in overlapping bins. (b) The energy
deposit spectrum with the ﬁtting results.

We applied the Landau-Gaussian convolution function3) to reproduce the peak shape of the MIP region,
and an exponential function to express the noise contribution. The Landau most probable value indicatesthe peak value corresponding to the energy loss of the
MIP. We ﬁtted the energy deposit spectrum with a sumof their functions and succeeded in reproducing the experimental data, shown in Fig. 1(b).
The ﬁtting result shows the Landau MPV was
71.13 ± 0.43 at the operation bias voltage of 50 V. The
noise contamination in the MIP region from 40 to 136
is estimated to be about 0.3%. Therefore the mass production ladder is almost noiseless in the MIP region.
In summary, we obtained one exact energy deposit
spectrum from measurements with 8 diﬀerent ADC conﬁgurations. The experimental spectrum was well reproduced by the sum of the convolution function and theexponential function. Also, the noise contamination in
the MIP region is about 0.3%. This means that the
DAC threshold value can be set low, leading to highdetection eﬃciency.
References
1) C. Aidala et al., Nucl. Instrum. Meth. Phys. Res. A 755,
44 (2014).
2) G. Nukazuka et al., ELPH Annu. Rep. (2022).
3) S. Hancock et al., Phys. Rev. A 28, 615 (1983).

Ⅱ-4. Hadron Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

The LV power system of INTT detector at RHIC
W. C. Tang,∗1 Y. Akiba,∗2 J. Bertaux,∗3 K. Fujiki,∗2,∗4 M. Fujiiwara,∗5 T. Hachiya,∗2,∗5 S. Hasegawa,∗2,∗6
M. Hata,∗5 H. Imai,∗2,∗4 M. Kano,∗5 T. Kato,∗2,∗4 T. Kondo,∗7 C. M. Kuo,∗1 R. S. Lu,∗8 I. Nakagawa,∗2
Y. Namimoto,∗2,∗5 R. Nouicer,∗9 G. Nukazuka,∗2 C. W. Shih,∗1 M. Shimomura,∗5 R. Shishikura,∗2,∗4
M. Stojanovic,∗3 Y. Sugiyama,∗5 R. Takahama,∗2,∗5 H. Tsujibata,∗5 M. Watanabe,∗5 and X. Wei∗3
The sPHENIX experiment is an upgrade projectof RHIC’s former PHENIX experiment and aims tostudy quark-gluon plasma.1) The INTermediate Tracker(INTT) is one of the sub-detectors of sPHENIX. INTT
inherits much of the electronics, such as the readout card
(ROC) and FPHX chips,2) from the FVTX detector.
The power system of INTT includes the high voltage(HV) system, which gives the bias voltage to the siliconsensors, and the low voltage (LV) system, which powers
up the FPHX chips and ROC.
The INTT power system is constructed in a power
crate (Fig. 1). This power crate is used for ladders test-

ing and for detector operation. On the top of the crateis the MPOD module which can produce 100 V as thehigh voltage system.
The second top of the crate is the switch distribution
board. There are 13 slots for switch distribution board
in total. Slots 1–11 from the left-hand side are used to
power up the ROCs, and the other two slots are used togive power to the FPHX power supply system.
The third top of the crate is the FPHX power supply
system which powers up the FPHX chips. The FPHX
power supply system consists of a controlling board andﬁltering boards. A controlling board is used to give out
the command to ﬁltering boards (Fig. 2). There can be
up to eight ﬁltering boards in a system. Each ﬁlteringboard can power up 8 ladders’ FPHX chips, which indicates that 64 ladders’ FPHX chips can be powered by
one power crate.

Fig. 2. FPHX power system ﬁltering board.

Fig. 1. INTT power crate system.
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Department of Physics, National Central University
RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteDepartment of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory

The Switch distribution board and FPHX power supply system are all connected to the PC by ethernet cables. One can easily enter the rack PC by using the NoMachine, ssh through the gateway, or control it locallyusing the keyboard and monitor to control the whole system. The Switch distribution board can be controlled by
the telnet command line, and the FPHX power supply
can be controlled by a perl script respectively. There is a
written script for controlling whole INTT power system
including HV and LV system, which can turn on andturn oﬀ all the power systems by one command.
References
1) Conceptual Design Report of sPHENIX (2018).
2) “FPHX: A new silicon strip readout chip for the PHENIX
experiment at RHIC,” 2009 IEEE Nuclear Science Symposium Conference Record.

- 59 -

Ⅱ-4. Hadron Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Signature of the gluon orbital angular momentum†
S. Bhattacharya,∗1 R. Boussarie,∗2 and Y. Hatta∗1,∗3
The Relativistic Heavy Ion Collider (RHIC) spin
program at Brookhaven National Laboratory has revealed that the gluon helicity contribution ∆G to theproton spin sum rule1
1
= ∆Σ + ∆G + Lq + Lg ,2
2

the gluon helciity GPD, respectively. We observe aninteresting interplay between the gluon OAM and thegluon helicity. The latter contribution was missed in
the previous calculation of a related observable.1)
In Fig. 1, we show our numerical result for the crosssection for the EIC kinematics at δϕ = ϕl⊥ − ϕ∆⊥ = 0
for Q2 = 2.7 GeV2 plotted as a function of skewness
ξ (longitudinal momentum fraction the proton loses inscattering). We see that the OAM and helicity contributions are comparable in magnitude, but with opposite signs. This is consistent with the theoreticalprediction3) that the gluon OAM and gluon helicity
parton distributions cancel in the small-x region. For
larger values of Q2 , our result (3) predicts that the twocontributions add up. This can be tested in experimentby varying Q2 .

(1)

is nonvanishing and likely sizable. Together with the
known quark helicity contribution ∆Σ ∼ 0.3, the result
indicates that parton helicities account for a signiﬁcant
fraction of the proton spin. Yet, there still remainhuge uncertainties
about the small-x contribution to∫1∆G = 0 dx∆G(x). Resolving this issue is one of the
major goals of the future Electron-Ion Collider (EIC).
Another obvious goal of the EIC is to measure the orbital angular momentum (OAM) of quarks and gluons
Lq,g . However, progress in this direction is relatively
slow, although there have been a few suggestions1) for
experimental observables in recent years. In this report we propose a new and promising observable forthe gluon OAM in Deep Inelastic Scattering and makea quantitative prediction for the EIC.
Speciﬁcally, we calculate longitudinal double spin
asymmetry (DSA) in exclusive dijet production inelectron-proton collisions ep → γ ∗ p → jjp′ where boththe incoming electron and proton are longitudinallypolarized. The part of the cross section which depends
on the proton and electron polarizations takes the formdσ hp hl ∼ hp hl cos(ϕl⊥ − ϕ∆⊥ )Re(A2 A∗3 ),d (pb/ GeV 2)

80

2
4q⊥

2 + µ2
q⊥

}

∗1
∗2
∗3

40
20
0
0.00040.00060.00080.00100.0012(2)
Fig. 1. Spin-dependent part of the cross section at Q2 =2.7 GeV2 as a function of the skewness variable ξ. The‘OAM’ and ‘Helicity’ contributions come from the Lg
and H̃g terms in (3), respectively.

In conclusion, we have made the ﬁrst quantitative
prediction for an observable sensitive to the parton
OAM at the EIC. Our result adequately demonstrates
the feasibility of accessing the gluon OAM from DSA.
It also emphasizes that, due to the admixture of thegluon helicity contribution, in order to extract the
OAM reliably, one needs an accurate determinationof ∆G(x) down to x ∼ 10−3 .

(3)]

Hg(2)∗ Lg − Hg(1)∗ H̃g ,where q⊥ is the transverse momentum of the two jets
which are assumed to be symmetric and 4µ2 = Q2
(1,2)
is the photon virtuality. Hg , Lg and H̃g are theCompton form factors of the unpolarized gluon generalized parton distribution (GPD), the gluon OAM and
†

60

20

where hl , hp = ±1 are the electron and proton helicities. ϕl⊥ and ϕ∆⊥ are the azimuthal angles of the outgoing lepton and the proton, respectively. A2 is the
known2) twist-2 amplitude for dijet production. A3
is a twist-3 amplitude which contains the OAM andwhich is calculated for the ﬁrst time in this work. The
details can be found in the published letter. Here weshow the ﬁnal result after certain approximations
Re(A2 A∗3 )[{∝ Re Hg(1)∗ +OAM
Helicity
Total

References
1) X. Ji et al., Phys. Rev. Lett. 118, 192004 (2017),
arXiv:1612.02438.
2) V. M. Braun et al., Phys. Rev. D 72, 034016 (2005),
arXiv:hep-ph/0505263.
3) Y. Hatta et al., Phys. Lett. B 781, 213 (2018),
arXiv:1802.02716.

Condensed from the article in Phys. Rev. Lett. 128, 182002(2022)
Department of Physics, Brookhaven National Laboratory
Ecole Polytechnique
RIKEN BNL Research Center- 60 -

5. Hadron Physics (Theory)6. Particle Physics

Ⅱ-6. Particle Physics
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

QST algebra
Y. Akiba∗1X̂p (εX̂q ) = ∓X̂q (εX̂p ). The reduction operator evaluates a n-fold vee product of PAs as follows

The standard model (SM) successully describes thenature, but it has at least 25 free parameters. Simple formulas with no free parameter for 24 SM parameters have been reported:1) 15 particle masses,
4 Cabbibo-Kobayashi-Maskawa (CKM) quark mixing
parameters, 3 neutrino mixing angles, the ﬁne structure constant, and the strong coupling constant. Moreover, the quarternion-spin-isospin (QST) model thatpredicts these formulas,2) and their implications ofgravity and cosmology3) have also been reported. This
article reports an update of the model.
In the QST model, the Planck time, tpl = 5.3912 ×
10−44 s, is the minimum time period in nature. tpl isa fundamental constant of nature, similar to the speedof light in vacuum c and the Planck constant ℏ. Consequently, the Planck length lpl = ctpl is the minimum distance in nature; therefore, a spacetime point
has a ﬁnite minimum size, and the number of spacetime points in a ﬁnite volume is also ﬁnite. Thus, eachspace-time point can be numbered.
In the QST model, the change in the state from aspacetime point |n⟩ to the subsequent spacetime point|n + 1⟩ is described as
(
) (
)
∑
|n + 1⟩ = 1 + dŜ EA [n] = 1 +δp [n]dŜpEA |n⟩,• If more than one of the X̂p ’s are identical[X̂p1 ∨ · · · ∨ X̂pn ] = 0.
• If X̂pk X̂pk+1 = X̂pk+1 X̂pk for any k (1 ≤ k < n),[X̂p1 ∨ · · · ∨ X̂pn ] = 0.
• If X̂pk X̂pk+1 = −X̂pk+1 X̂pk for all k (1 ≤ k < n),[X̂p1 ∨ · · · ∨ X̂pn ] = X̂p1 · · · X̂pn .
The change of physical state from |n⟩ to |n + N ⟩ isexpressed as|n + N ⟩ = (1 + dŜ EA [n + N − 1])(· · · (1 + dŜ EA [n])|n⟩In the model, it is shown that the product of any two
EAs vanishes, that is, dŜpEA dŜqEA = 0. Thus(∑)
1 + dŜ EA [k] = exp(dŜ EA [k]) = exp
δp [k]dŜpEA|n + N ⟩ = exp(n+N −1∑k=n)dS[k] |n⟩This formula represents the physical action from one
spacetime point |n⟩ to another spacetime point |n+N ⟩along with one path. Thus, the physical state |tf ⟩ isthe sum of all of such actions.
(∑
)
∑
exp
dŜ EA [k] |xi ⟩,|xf ⟩ =∑
where dŜ EA [n] =δp [n]dŜpEA is the change in thestate from |n⟩ to |n + 1⟩, and δp [n] = 0 or 1, anddŜpEA (p = 1, · · · , 49) are operators that are denoted
as elementary actions (EAs). This implies that eachspacetime point is associated with a 49-dimentional
vector space that describes the physical action, andan EA is the basis of the vector space. We denote thisvector space as the EA space. Here the coeﬃcient ofdŜpEA is not a real number; however it is limited toeither 0 or 1. This inidicates that the coeﬃcient ﬁeldof the EA space is not real R, but a ﬁnite ﬁeld F2 ={0, 1}.
In the QST model, an EA is a 48-fold product ofoperators that we denote as primordial actions (PAs).

where the ﬁrst sum runs over all possible paths
from|xi ⟩ to |xf ⟩. This equation corresponds to thefollowing path integral formula∫|tf ⟩ =
Dϕ exp (idS[ϕ]) |ti ⟩
( ∫
)
∫
4
=
Dϕ exp i L[ϕ]d x |ti ⟩This indicates that an EA dŜpEA corresponds to a termof Lagrangian as follows

dŜpEA = [X̂p1 ∨ X̂p2 ∨ · · · ∨ X̂p48 ],dŜpEA ↔ Lp d4 x

where ∨ is a binary product operator in the model analogous to the wedge product ∧ in the exterior algebra,X̂pk are PAs, and [] represents a “reduction” operator
that evaluates a vee product in term of normal product. A PA is one of the following 64 operators.

In the QST model, all terms of the standard model
Lagrangian are derived as one of the 49 EAs.
A paper describing the QST model is still inprogress.

{I µ σ ν τ a , ετ a , εi, εI [c−a] τ a , εiτ 3 , −εI c , −εi, ε, −ε, i, 1},

Referenceswhere ε is the sign operator. If X̂p X̂q = ±X̂q X̂p then

1) Y. Akiba, RIKEN Accel. Prog. Rep. 54, 69 (2021).
2) Y. Akiba, RIKEN Accel. Prog. Rep. 54, 70 (2021).
3) Y. Akiba, RIKEN Accel. Prog. Rep. 54, 71 (2021).

∗1

RIKEN Nishina Center- 61 -

Ⅱ-6. Particle Physics

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Twelfth-order QED contributions to the muon g −2
R. Yamazaki∗1,∗2 and M. Nio∗2,∗1
The anomalous magnetic moment of the muon, aµ ≡(gµ − 2)/2, has occupied a central role in testing thevalidity of the standard model of elementary particles (SM). The new measurement of aµ at Fermilab1)
is consistent with that at Brookhaven,2) and the longstanding tension between experiment and theory remains unresolved. The average of the two experiments
and the SM prediction3) are given asaµ (Exp) = 116 592 061 (41) × 10−11 ,−11aµ (SM) = 116 591 810 (43) × 10

,

(1)
(2)

respectively, and the diﬀerence is (251 ± 59) × 10−11
corresponding to 4.2 σ.
The theoretical prediction of aµ has been calculated
by considering all three forces of SM. The contribution
from the quantum electrodynamics (QED) is dominant
and has been determined up to the tenth order of theperturbation theory. It has been considered suﬃciently
well known as its uncertainty is 1.0 × 10−12 . The assigned uncertainty was derived from the rough estimateof the leading-order contribution of the twelfth-orderterm. Recently, we have calculated, not guessed, thetwo types of Feynman diagrams shown in Fig. 1 thatare supposed to give the leading contributions in thetwelfth order.

Fig. 1. Some Feynman vertex diagrams of the twelfth-order
QED containing light-by-light scattering subdiagrams.

Because the muon is about two hundred times heavier than the electron, enhancement factors arise in some
QED contributions to aµ . One famous origin of theenhancement is a light-by-light scattering vertex diagram (LL6), in which an external magnetic photon is
attached to an electron loop. Another is a vacuumpolarization subdiagram (VP) consisting of an electronloop. The left diagram of Fig. 1 is a combination of
two enhancement mechanisms of the twelfth order ofthe QED perturbation theory. We have calculated its
numerical contribution taking into account all possible
insertions of three second-order VPs (P2s) to LL6. In
addition, diagrams with insertions of one fourth-order
VP (P4) and two P2s to LL6 were calculated. The coeﬃcients of (α/π)6 , where α is the ﬁne-structure constant, are obtained as follows:∗1∗2

Department of Physics, Saitama University
RIKEN Nishina Center- 62 -(e)a(12)P2(e) P2(e) P2(e) ] = 2415.256 (53), (3)µ [LL6(e)a(12)P2(µ) P2(e) P2(e) ] = 367.974 (15),µ [LL6

(4)

(e)
a(12)
P4(e) P2(e) ] = 1451.106 (91),µ [LL6(5)

where a superscript (e) or (µ) of LL6, P2, or P4 indicates a species of its fermion loop. The sum of thethree gives the leading contribution of the twelfth-orderQED: α 6× 4230 = 0.665 × 10−12 .
(6)π

It is within the uncertainty assigned to the QED contribution to aµ .
A new enhancement mechanism appears at thetwelfth order. The right diagram of Fig. 1 (LL6 LL6)
contains a “child” LL6 as a subdiagram. When themass of an external fermion is much heavier than thatof a loop fermion, the slope of F1 form factor of LL6
has a large enhancement factor4)


2
2 
mµ
2 dF1 (q ) mµ∝∼ 40000 .
(7)
dq 2 q2 =0
me

It is uncertain that such a critical enhancement factor exists in the LL6 LL6 contribution to aµ . Therefore,
we calculated LL6 LL6 without any approximation except for numerical integration. The 360 Feynman vertex diagrams of the gauge-invariant set LL6 LL6 canbe reduced to sixteen independent integrals. Each of
the integrands consists of about 50 MByte text ﬁles. In
principle, no renormalization is required for LL6 LL6.
However, to conduct numerical integration, an integrand needs ultra-violet (UV) counter terms that cancel
the UV divergences of a child LL6 vertex subdiagram
and a light-by-light scattering subdiagram (LL). The
UV counter terms we constructed are the form factor
F1 (0) for a child LL6 and the light-by-light scattering
tensor Πµνρσ (0, 0, 0, 0) for a LL. The sum of the UV
counter terms exactly vanishes when all gauge-invariant
diagrams are summed up. The numerical calculation
has been performed, and the result will be reported
elsewhere.
Numerical calculations were conducted on RIKEN’s
supercomputer HOKUSAI BigWaterfall. This work
was partly supported by KAKENHI 16K05338,
20H05646, and 22K03646.
References
1) B. Abi et al. (Muon g−2 Collaboration), Phys. Rev. Lett.
126, 141801 (2021).
2) G. W. Bennett et al. (Muon g −2 Collaboration), Phys.
Rev. D 73, 072003 (2006).
3) T. Aoyama et al., Phys. Rep. 887, 1 (2020).
4) E. H. Wichmann et al., Phys. Rev. 101, 843 (1956).

7. Astrophysics and Astro-Glaciology

Ⅱ-7. Astrophysics and Astro-Glaciology
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Demonstration of multiplexing lobster-eye optics
Y. Zhou,∗1,∗3 T. Mihara,∗1,∗2 T. Tamagawa,∗1,∗2,∗3 and K. Uchiyama∗1,∗3
Wide-ﬁeld X-ray monitor is essential in astronomy tocatch short-time events, such as gamma-ray bursts,1)
and neutron-star mergers.2) The all-sky X-ray monitor,
MAXI,3) which we have operated on the ISS since 2009,
has proven its usefulness. As an extension of MAXI to
the soft X-ray band and precise-imaging, we introduced
the multiplexing lobster-eye (MuLE) optics.4) we haverecently performed veriﬁcation experiments of MuLEfor the ﬁrst time. In this report, we present the angularresolution of MuLE obtained with Ti Kα (4.5 keV) Xrays.
The test setup is shown in Fig. 1. We used micro
porous optics (MPOs) made by NNVT company with
R = 750 mm and the size of 43 mm square. The CMOS
image sensor was Gpixel 400BSI-TVISB, whose size was
22.5 mm square. X-rays through the three MPOs focus
on a single CMOS placed on the focal plane at a radiusof R/2, where R was the curvature of MPO. The ﬁeldof-view of a mirror is 3 deg × ±1.5 deg. Each mirror
was centered at 0 deg, 9 deg and 18 deg like steppingstones. We added the other side at −9 deg and −18 deg
to make one unit. Using 3 units, the whole ±20 deg ×±1.5 deg sky can be covered. This CMOS has a goodenergy resolution. We measured the energy resolutionof the CMOS for Ti Kα to be ∆E/E = 3.7% (FWHM)
with single-pixel events at room temperature.

3.85 m. The focal length was measured as 345 mm forthis diverging light. In our experiment, the CMOS was
set in this distance. Focal length for the parallel light
was calculated to be 379 mm. It is close to the designed
value (375 mm).
2 MPOs were placed on a mount, and measured Seg-0
and Seg-1 ﬁrst. The Seg-0 mirror was rotated clockwisearound the optical axis by 10 deg, while Seg-1 was 0 deg
upright. The direction of the cross arm identiﬁes the
MPO which the X-ray comes from. After we measured
Seg-0 and Seg-1 we moved the whole mount so that the
Seg-1 MPO can locate Seg-2. Then we measured Seg2. Although Seg-1 and Seg-2 are the same MPO, theimage of the Seg-2 was rotated anticlockwise by 10 deg
in Fig. 1 for understanding.
A demerit of the MuLE is that the CMOS is placedin a slanted way for the Seg-1 and Seg-2, which makes
the image worse in the X direction in our setting.
By ﬁtting the peak of the core in the image, the widthof the focus can be measured. The angular resolution(σ) was shown in Fig. 2. It distributed between 4 arcmin to 8 arcmin, which is acceptable. Some jumping
data points are due to irregularities on the LE surface.

Fig. 2. Incident X-ray angle and position resolution (σ).

Fig. 1. MuLE experiment and X-ray images of three LE.
The brightness corresponds to X-ray intensity.

We showed the focus images in Fig. 1 right. The
distance of the Ti X-ray generator to the MPO was
∗1
∗2
∗3

RIKEN Nishina Center
High Energy Astrophysics Laboratory, RIKEN Cluster for
Pioneering Research
Department of Physics, Tokyo University of Science- 63 -

This report demonstrated the MuLE system worked
as expected. MuLE system can be used in small satellites or ISS payloads to compensate for the soft X-ray
performance of MAXI.
References
1) R. Vanderspek et al., Astrophy. J. 617, 1251 (2004).
2) B. P. Abbott et al., Phys. Rev. Lett. 119, 161101 (2017).
3) M. Matsuoka et al., Publ. Astron. Soc. J. 61, 999 (2009).
4) T. Tamagawa et al., J. Astron. Telesc. Instrum. Syst. 6,025003 (2020).

Ⅱ-7. Astrophysics and Astro-Glaciology

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Direct determination of the activation energy for diﬀusion of OH
radicals on water ice†
A. Miyazaki,∗1 M. Tsuge,∗1 H. Hidaka,∗1 Y. Nakai,∗2 and N. Watanabe∗1
Physicochemical processes such as surface reactionsof radicals, photolysis by ultraviolet (UV) irradiation,and ion bombardment on interstellar icy grains areindispensable for chemical evolution during star formation. The chemical evolution begins in molecular clouds where the temperature is as low as 10 K.
In molecular clouds, the hydrogenation of primordial
atomic and molecular species is crucial because hydrogen atoms can migrate and encounter reaction partners
on the grain surface even at ∼10 K.1–7) During temperature elevation in star-forming regions, heavier species
can diﬀuse on the ice and many types of complex organic molecules (COMs) are considered to be produced
through reactions among heavier species, particularly
radicals. Thus, the behavior of radicals on the ice surface should be investigated to understand the formation pathways of COMs. OH radical would be one of
the most abundant radicals on ice surface as they canbe produced through photolysis of H2 O and hydrogenation of O atoms on the ice surface. Therefore, OH radicals are expected to participate in various physicochemical processes on ice surface. However, conventional
methods for detecting OH radicals, such as Raman, infrared, and electron spin resonance spectroscopies, are
not applicable because of their low detection eﬃciencies
and non-surface selectivity. In this study, we applied a
combination of photostimulated desorption (PSD) andresonance-enhanced multiphoton ionization (REMPI)
to facilitate direct detection of OH radicals on the ice
surface.8) Using this PSD-REMPI method, we determined the activation energy for diﬀusion (Ediﬀ ) of OH
radicals on compact amorphous solid water (c-ASW),
because the surface diﬀusion of radicals often becomesa rate-limiting process in reactions involving radicals.
The c-ASW samples were deposited on a sapphiredisk at 100 K by introducing the water vapor into an ultrahigh vacuum chamber (∼10−8 Pa). After the preparation of ASW sample, OH radicals were produced via
photolysis of water molecules using a deuterium lampin the temperature range of 54–80 K. In this photolysis, H2 O is dissociated mainly into H + OH with minor
channels, H2 + O and 2H + O, and as secondary products, H2 and O2 are also produced on the surface. To
avoid the undesired eﬀect of these species other thanOH, the experiments were performed at temperatures
above 54 K where hydrogen and oxygen cannot stayon the surface. The OH radicals on the sample surface
were detected with the PSD-REMPI method.8) The OH†∗1∗2

Condensed from the article in Astrophys. J. Lett. 940, L2(2022)
Institute of Low Temperature Science, Hokkaido University
RIKEN Nishina Center- 64 -

radicals were photodesorbed by weak-pulsed laser radiation at 532 nm from an Nd:YAG laser. The photon energy at 532 nm is below the dissociation energy of H2 O.
Photodesorbed OH radicals were selectively ionized bythe (2 + 1) REMPI process above the c-ASW surface
and detected with a time-of-ﬂight mass spectrometer.
We performed two types of measurements. In the ﬁrst
measurement, the OH intensities were monitored during UV exposure. We monitored the OH intensities inthe steady state during UV irradiation. In the othermeasurement, the OH intensities were measured following a particular period of UV exposure. Note that
we can selectively monitor OH radicals based on onephoton chemical process.8)
When monitoring OH during UV exposure, we foundthat the OH intensities in steady state gradually decreased with the temperature of c-ASW in the range ofapproximately 60–80 K. We experimentally conﬁrmedthat OH radicals were lost through OH–OH recombination rather than thermal desorption of OH. The recombination rate should be limited by the diﬀusion of
OH radicals on the c-ASW surface because the radicalradical reaction itself is barrierless. By analyzing therecombination rate with the Arrhenius type formula,
the activation barrier of surface diﬀusion, Ediﬀ , wasevaluated to be 0.14 ± 0.01 eV (1650 ± 60 K). Furthermore, in the other measurement of OH monitoring after
UV exposure, the OH intensities decreased with timeafter UV termination. Again, considering that this decrease is dominated by OH–OH recombination, we derived Ediﬀ to be 0.13 ± 0.01 eV (1540 ± 80 K). Thisvalue is consistent with the previously obtained value.
Under a simple assumption that the activation energyof diﬀusion has the single value of 1650 K, the OH radicals can migrate over 100 nm on the icy dust within 105
years at temperatures above 36 ± 1 K. The present results suggest that OH reactions start at approximately
36 K and become important in the warming-up of starforming regions. Note that we do not exclude thepossibility that the OH radicals drift to a certain extent through shallower sites even at temperatures below
36 K.
References
1) N. Watanabe et al., Prog. Surf. Sci. 83, 439 (2008).
2) T. Hama et al., Chem. Rev. 113, 8783 (2013).
3) N. Watanabe et al., Astrophys. J. Lett. 571, L173
(2002).
4) S. Ioppolo et al., Astrophys. J. 686, 1474 (2008).
5) N. Miyauchi et al., Chem. Phys. Lett. 456, 27 (2008).
6) F. Dulieu et al., Astron. Astrophys. 512, A30 (2010).
7) H. Hidaka et al., Chem. Phys. 13, 15798 (2011).
8) A. Miyazaki et al., Phys. Rev. A 102, 052822 (2020).

Ⅱ-7. Astrophysics and Astro-Glaciology
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Polarized X-rays emitted from a magnetar†
K. Uchiyama,∗1,∗2 R. Taverna,∗3 R. Turolla,∗3,∗6 F. Muleri,∗4 J. Heyl,∗5 S. Zane,∗6 L. Baldini,∗7,∗8
D. González-Caniulef,∗5 M. Bachetti,∗9 J. Rankin,∗4 I. Caiazzo,∗10 N. D. Lalla,∗11 V. Doroshenko,∗12
M. Errando,∗13 E. Gau,∗13 D. Kırmızıbayrak,∗5 H. Krawczynski,∗13 M. Negro,∗14,∗15 M. Ng,∗16 N. Omodei,∗11
A. Possenti,∗9 T. Tamagawa,∗1,∗2,∗17 and M. C. Weisskopf∗18 on behalf of the IXPE magnetar WG
N 0°
30°

lar
iza

tio
n

an

gle

Magnetars are neutron stars with ultra-strong magnetic ﬁelds. Magnetars exhibit steady X-ray pulsed
emissions with a luminosity of approximately 1033 –1035 erg s−1 , spin period P of approximately 0.1–12 s,
and large spin-down rates Ṗ of approximately 10−14 –10−10 s s−1 . This translates into magnetic ﬁelds of up
to B approximately 1015 G, assuming a conventional
spin-down model. The external magnetic ﬁeld of magnetars is expected to have a toroidal component thattwists the ﬁeld lines. Because charged particles must
ﬂow along the closed magnetic ﬁeld lines to sustain theﬁeld, the star magnetosphere becomes optically-thickduring resonant Compton scattering (RCS).1) Becauseof its strong magnetic ﬁeld, magnetar X-ray emission
is linearly polarized in two normal modes, namely, theordinary (O) and extraordinary (X) modes, and upon
reprocessing via RCS, X-mode photons become dominant.
4U 0142 + 61 is the brightest persistent magnetar
with an unabsorbed ﬂux of 6 × 10−11 erg s−1 cm−2in the 2–10 keV range. Here, we report on the polarimetric observation of 4U 0142 + 61 conducted by
the Imaging X-ray Polarimetry Explorer (IXPE) fromJanuary 31, 2022 to February 27, 2022 for a total onsource time of 840 ks.
Results are shown in Fig. 1 in the form of a polar plot
where the polarization degree (PD) is the radial coordinate and polarization angle (PA) the azimuth. The
measured PD is 15 ± 1% at low energies (2–4 keV).
At 4–5 keV PD becomes consistent with zero and thenincreases to 35 ± 7% at 5.5–8 keV. The PA is approxi-

5.5-8.0 keV

Po

60°

E 90°

-30°

90 deg rotation-60°

2.0-3.0 keV 4.0-4.8 keV
4.8-5.5 keV

3.0-4.0 keV
10

20

30

40

50

-90° W

Polarization degree [deg]Fig. 1. Polar plot showing the energy dependence of themeasured PD and PA. Contours enclose the 68.3% conﬁdence level regions. Stars indicate the corresponding
PD and PA calculated using the RCS model.

mately 50◦ East of North at energies below 4 keV andswings by 90◦ , settling at 40◦ West of North, above
5 keV.
The polarization pattern as a function of energy,
with a minimum of PD and swing of PA by 90◦ at
approximately 4–5 keV, suggests that the X-ray emission from 4U 0142 + 61 is characterized by two distinct
components polarized in two diﬀerent normal modes.
The low-energy component is thought to be producedby thermal surface emission while the high-energy
component by photons up-scattered in the magnetosphere. The measured polarization fraction at highenergies (35% at 5.5–8 keV) is indeed compatible withthe theoretical expectations of the RCS model andsuggests that X-mode photons dominate. Although
the measured polarization fraction at low energies (2–4 keV) diﬀers from the predictions of published theoretical models,2) we found that the radiation emitted
from a condensed3) equatorial belt results in a predominance of O-mode photons with PD of approximately
15%.
In conclusion, the positive detection of polarized
emission from 4U 0142 + 61 by IXPE further supports the magnetar model. In particular, the distinctive energy-dependent pattern can be explained by assuming emission from the bare condensed surface reprocessed by RCS in the twisted magnetosphere.

†

Condensed from the article in Science 378, 646 (2022)
RIKEN Nishina Center∗2 Department of Physics, Tokyo University of Science∗3 Department of Physics and Astronomy, University of Padova∗4 Istituto di Astroﬁsica e Planetologia Spaziali∗5 Department of Physics and Astronomy, University of British
Columbia∗6 Mullard Space Science Lab., University College London∗7 Dipartimento di Fisica Enrico Fermi, Università di Pisa
∗8 Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
∗9 Osservatorio Astronomico di Cagliari, INAF
∗10 TAPIR at Caltech∗11 Department of Physics, Stanford University∗12 Institut für Astronomie und Astrophysik, UniversitätTübingen∗13 Physics Department and McDonnell Center for the Space
Sciences, Washington University∗14 University of Maryland, Baltimore Country∗15 NASA Goddard Space Flight Center∗16 Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology∗17 RIKEN Cluster for Pioneering Research∗18 NASA Marshall Space Flight Center∗1

References
1) C. Thompson et al., Astrophys. J. 574, 332 (2002).
2) R. Taverna et al., Mon. Not. R. Astron. Soc. 492, 5057
(2020).
3) A. Y. Potekhin et al., Astron. Astrophys. 546, A121
(2012).

- 65 -

8. Accelerator

Ⅱ-8. Accelerator
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production of high intense Ca-ion beam for RILAC II acceleration
T. Nagatomo,∗1 Y. Higurashi,∗1 J. Ohnishi,∗1 and T. Nakagawa∗1
Calcium(Ca)-48-ion beam is indispensable for studying light nuclei with excess neutrons. The 48 Ca beam
was obtained from RILAC as an injector for RIBF accelerators before the upgrade of RILAC with superconducting (SC) acceleration cavities.1) The injection line
for the RIBF cyclotrons was removed owing to the construction required for the upgrade, and has not been restored at present. Currently, the only way is to use RILAC II, which is mainly used to inject heavy ion beams(krypton, xenon, uranium), as the injector for RIBF.
Despite the global shortage of 48 Ca (natural abundance= 0.187%) samples, it is estimated that low-level enriched samples (∼20%) will be available within 2 years.
However, the low enrichment of 20% implies that only
20% of the produced Ca beam can be used. Therefore,in accordance with the Ca beam acceleration scheme
using RILAC II, we conducted a test to extract ultraintense Ca11+ -beam above 100 µA from a SC-ECR ion
source (SC-ECRIS).
The experiment was conducted using an SC-ECRIS
for RILAC (R28G-K),2,3) which exhibits the same performance as that of RILAC II. An ion-extraction voltage of 13.00 kV was applied to ﬁt to the acceleration
scheme. We selected a high-temperature oven (HTO),4)
which was used in the previous Ca16+ beam production
last year with good results.5) Compared to the previous
test, because the Ca11+ has a lower charge state, thestable plasma conditions, such as the electron temperature and ion conﬁnement time, diﬀer. The magnetic
mirror was set to lower ﬁeld strength than the Ca16+
case, similar to the Ref. 6), resulting in the decreased
electron temperature. Natural CaO samples were prepared using the same procedure as in a previous study.5)
Two evaporation methods to obtain the neutral Ca gas
were attempted: direct heating of the sample at temperatures up to 2000◦ C (DH), and use of the redox
reaction of 3CaO + 2Al → 3Ca + Al2 O3 to lower the Ca
evaporation temperature (RR). The DH method is thesame method as in the Ca16+ beam production, andRR is a common method as presented in Ref. 6). The
temperature was controlled by the applied power on
the HTO (PHTO ). Oxygen (O2 ) and helium (He) gases
were tested as support gases (SGs) to maintain a stable
plasma. The total microwave power with frequencies of
18 and 28 GHz, Ptot. , as well as the SG ﬂow rate were
adjusted to optimize the beam intensity and stability.
Table 1 summarizes the obtained intensities of 40 Caion beam extracted from R28G-K along with the experimental conditions. The data for the ionic charge state
Q = 16 are obtained from a previous study.5) Here,
Istart and Istop represent the beam intensities at the
beginning and end of the operation (duration time ∆t),
∗1

RIKEN Nishina Center- 67 -

Table 1. 40 Ca ion beam intensities with the charge state Q
together with the some experimental conditions such as
the support gas (SG) and the Ca evaporation method(Meth.). Measurements were performed over a period of∆t. See text for other abbreviations.
Q

SG Meth.

11
11
11
11
16
16
16

O2
O2
O2
He
O2
O2
O2

DH
DH
RR
RR
DH
DH
DH

Ptot.
kW
3.4
2.7
2.8
2.1
3.0
3.0
3.0

PHTO
W
900.
800.
190.
190.
720.
660.
600.

∆t
hours
9.3
14.3
17.9
7.7
16.3
39.7
37.1

Istart
µA
242.
101.
74.
105.
84.
35.
25.

Istop
µA
204.
59.
33.
90.
85.
70.
30.

respectively. As shown in Table 1, in all cases of Ca16+ ,the beam intensity gradually increased, and eventuallyreached to constant values. However, the Ca11+ beam
intensity tended to decrease with the elapsed time. This
trend is more pronounced in the O2 case than in the
He case. Note that, in the previous study,5) the Ca16+
beam intensity was also tested with He support gas;
however, it was found to be only half that of the O2
support gas. The DH method seems to cause a chemical reaction between the tungsten crucible and the CaO
sample at elevated temperature of ∼2000◦ C. From the
M/Q analyses using the analyzing magnet, when the
PHTO is 700 W, the heavy-ion beams, which appear
to be tungsten ions, are not noticeable; however, as
the PHTO is increased to 800 W and 900 W, they become more pronounced. Owing to the chemical reaction, the RR method, which can be used at lower temperature, is preferable to produce low-charge Ca ion
beams. Although the measurement time was not suﬃciently long, the consumption rate of Ca was estimatedto be ∼0.7 mg/h using the RR method using the He gas
to produce a Ca11+ beam of approximately 100 µA.
This study has only just begun, and the search forconditions that reduce the Ca consumption is ongoing.
References
1) N. Sakamoto et al., Proc. SRF2019, Dresden, Germany (2019), p. WETEB1.
2) T. Nagatomo et al., Rev. Sci. Instrum. 91, 023318(2020).
3) G. D. Alton et al., Rev. Sci. Instrum. 65, 775 (1994).
4) J. Ohnishi et al., Proc. ECRIS2018, Catania, Italy(2018), p. 180.
5) T. Nagatomo et al., RIKEN Accel. Prog. Rep. 55, S18(2022).
6) J. Y. Benitez et al., Rev. Sci. Instrum. 85, 02A961(2014).

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Upgrade of rf control system for RILAC injector
K. Yamada,∗1 K. Suda,∗1 T. Ohki,∗2 H. Yamauchi,∗2 K. Oyamada,∗2 M. Tamura,∗2 A. Yusa,∗2 K. Kaneko,∗2 and
N. Sakamoto∗1
The RIKEN linear accelerator (RILAC)1,2) and its
downstream superconducting linac (SRILAC)3) actively supply beams for research studies involving super heavy element. The injection section of the RILAC
was constructed in the 1990s and consists of three main
instruments: a buncher, a folded-coaxial-type radiofrequency (rf) quadrupole linac (FCRFQ),4) and a rebuncher.
The old rf control systems at RIKEN were very poorin terms of reproducibility and operability, and their old
analog low-level circuits caused a lack of rf voltage andphase stability. One of the major reasons is that they
are aging, having been manufactured nearly 30 years
ago; another reason is that the resolution is insuﬃcientbecause the set values are speciﬁed using analog voltages. In addition, the feedback parameter settings must
be adjusted in the circuit itself and cannot be changed
easily during operation. Therefore, we decided to improve the controllability and the resulting rf stability
by upgrading the control system with a programmable
logic controller (PLC) and a new digital low-level (LL)
circuit.
The old control system and wiring were removed andthe new system was installed from July to August 2022,
and the wiring to each control target such as the resonators, ampliﬁers, and DC power supply was connected in September. Figure 1 depicts the front view of
the new control system. The left half depicts the cabinet with the PLC and motor drivers, and the right side
depicts the cabinet with digital LL circuits and oscilloscopes. All the 12 motors, three for the RFQ resonator,
four for the RFQ ampliﬁer, and ﬁve for the re-buncher
resonator, were updated to new stepping motors. All
devices are controlled by a single PLC, similar to otherrf control systems in RIBF. The new control system allows for better reproducible positioning of each drive

mechanism, and the frequency tuner, which was previously operated manually, is now controlled automatically. The rf system is interfaced by EPICS for remote
operation and monitoring, which is connected to the
PLC through a TCP/IP connection.
The digital LL circuit is an original one based on
the circuit for SRILAC,5) and it supports a frequency
range of 17–40 MHz. The circuit integrates automatic
gain control, phase-lock loop, and phase diﬀerence detection for automatic tuning. These signals acquiredby on-board 16-bit ADCs are I/Q demodulated using
a ﬁeld programmable gate array, and a direct digitalsynthesizer output is I/Q modulated and output as anrf signal. Similar to the SRILAC, various parameterssuch as the voltage set value, phase set value, and internal status are read and written by the PLC in parallel
communication with the digital LL circuit. As all communication with the circuit is done digitally, all setting
parameters such as the feedback parameters and thresholds can be set reliably, and the settings can be changed
remotely.
Figure 2 presents a one-day trend graph depicting therf voltage and phase stability of the RFQ. It is clear thatthe new system has signiﬁcantly improved the rf stability. We plan to replace the analog LL system of the
RILAC and RRC with an equivalent digital LL system
next ﬁscal year.

Rf phase

Rf voltage

Old analog LL circuit

㼼0.1%
㼼 0.1 deg.

㼼0.1%
㼼 0.1 deg.
New digital LL circuit
1 day

Fig. 2. Trend graph for rf voltage and phase of the RFQ
before (upper panel) and after (lower panel) the upgrade.

References

Fig. 1. New rf control system for the RILAC injector. The
PLC and motor drivers are visible inside the door.
∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

- 68 -

1) M. Odera et al., Nucl. Instrum. Methods Phys. Res. A
227, 187 (1984).
2) O. Kamigaito et al., Rev. Sci. Instrum. 76, 013306(2005).
3) K. Yamada et al., Proc. SRF2021, (2021), p. 167.
4) O. Kamigaito et al., Rev. Sci. Instrum. 70, 4523 (1999).
5) K. Suda et al., Proc. SRF2021, (2021), p. 666.

Ⅱ-8. Accelerator
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Beam proﬁle measurement using helium gas light emission forsuperheavy element search experiment†
T. Watanabe,∗1 A. Kamoshida,∗2,∗1 T. Nishi,∗1 A. Uchiyama,∗1 and K. Kaneko∗3
The newly constructed superconducting linear accelerator (SRILAC)1) continues to operate with the aimof discovering new superheavy elements following thediscovery of 113 Nihonium,2) and production medical
radiation isotopes At.3) In this experimental search forsuperheavy elements, owing to the demand to extend
the durability of the expensive Cm target to the best
extent possible the accelerated V beam must be adequately widened. Therefore, a He gas light emission
monitor (HeLM) has been introduced to measure thebeam width non-destructively and constantly.
Figure 1 shows the schematic of the diﬀerential
pumping system, target chamber for the GARIS-III,and HeLM. The beam originates from the left side andhits the Cm targets. As helium gas is ﬂowing in thetarget chamber, the electrons of helium gas is excitedby the collision with the beam. By monitoring theemitted light with a CCD camera when the excitedelectrons are de-excited, the beam proﬁle can be obtained continuously. The image data obtained is sent
to an image analysis PC with a video server for digitalprocessing. These measurements and data analysis arecontrolled and programed with LabVIEW and the analyzed data are shared with a large-scale EPICS control
system.

(a)

1 Minute
1 Hour
1 Day

Target wheel

View port

View port

N2-gas-jet curtain

PIN diode

N2

from
SRILAC

Motor

MBP

TMP
TMP

TMP

MBP

To
GARIS-III

Fig. 2. The front panels programmed with LabVIEW andmeasurement results. (a) The integrating the brightness in the direction of travel of the beam and the result of Gauss ﬁt, (b) image of He gas emission, (c) valueof Gauss ﬁt 1σ and the deviation from the center, (d)selection of the ﬁtting region (manual, direct numericalinput) and (e) Record of the Gauss ﬁt 1σ.

Ta and C Slit
Faraday cup

1485 mmFig. 1. Schematic of the diﬀerential pumping system, target chamber for GARIS III and HeLM.

Figure 2 shows the front panels programmed withLabVIEW and measurement results. Recently, thebeam width measurement with the HeLM and thebeam optics calculation4) facilitated the precise beam
size control at the Cm target. Furthermore, the correlation between the beam size measured with the HeLM
†
∗1
∗2
∗3

(d)

(e)

CCD Camera Mirror

TMP

Integrated

Beam

(b)

Target chamber

Differential pumping system
TMP

(c)

and elastic scattering counts measured with a semiconductor detector are conﬁrmed to be quite consistent.
References
1) N. Sakamoto, J. Part. Accel. Soc. Jpn. 17, 70 (2020).
2) K. Morita et al., J. Phys. Soc. Jpn. 81, 103201 (2012).
3) H. Haba, Drug Deliv. Syst. 35, 114 (2020).
4) T. Nishi et al., Proc. 64th ICFA Advanced Beam
Dynamics Workshop on High-Intensity and HighBrightness Hadron Beams (HB202), Illinois, USA, 202110, THBC1.

Condensed from the article in Proc. 19th Annu. Meeting
Part. Accel. Soc. Jpn., to be published (2022)
RIKEN Nishina Center
National Instruments Japan Corporation
SHI Accelerator Service Ltd.

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Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Improvement of the high temperature superconducting properties for
the HTc SQUID current meter
T. Watanabe,∗1 I. Watanabe,∗1 and U. Widyaiswari∗1
To measure the DC current of heavy-ion beams nondestructively at high resolution, we have developed
a high critical temperature (HTc) superconducting
quantum interference device (SQUID) beam current
meter for use in the radioactive isotope beam factory(RIBF). Aiming at its practical use, the HTc SQUID
monitor was installed at RIBF and a 1 µA heavy ion
beam was successfully measuried with 100 nA resolution with this current meter.1,2)
Although we could measure the intensity of a subµA beam, a minimum current resolution of more than
two orders of magnitude lower is required at the RIBF.
With the aim of higher sensitivity and miniaturizationof the SQUID current meter, we have started the investigation on a new method. Figure 1 shows a newscheme based on a direct coupling between an induced
magnetic ﬂux and the HTc SQUID.3) To fabricate an
induction ring and a shielding ring, we have been investigating to coat and molten a thin layer (20–50 µm) of
Bi2 -Sr2 -Ca1 -Cu2 -Ox (Bi2212) on a Ag substrate. The
critical temperature of Bi2212 must be over 77 K, because it is cooled at a temperature of liquid N2 . To
conﬁrm the high critical temperature and to realize thehigh critical current which is related to the shielding effect of the environmental magnetic noise, we have been
improving the superconducting properties. We foundthe properties of Bi2212 are improved by annealing
it in the high purity Ar atmosphere. To obtain the
better Bi2212 properties, we searched the critical temperature and critical current with a magnetic property
measurement system by changing the annealing temperatures and annealing time. The measured results
are shown in Fig. 2 and summarized in Table 1. The

Magnetic Moment (emu)

5 10

H = 100 Oe
0
-5 10

-4

-1 10

-3

-1.5 10

-3

-2 10

-3

Magnetic Moment (emu)(a)

ZFC No Annieled
FC No Annielded
ZFC Annieled
FC Annieled

40

50

60

70

80

90

100

110

120

Temperature (K)
4 10

-4

3 10

-4

2 10

-4

1 10

-4

-1 10

-4

-2 10

-4

-3 10

-4

No Annealed
Annealed0

T = 77 K

-4

-4 10
3
-1 10

(b)

-5 10

2

0

5 10

2

1 10

3

Field (Oe)Fig. 2. Measured properties of the Bi2212 with a magnetic
property measurement system.

Table 1. The obtained critical temperatures and criticalcurrents.
Critical temperature (K)Critical current (A/cm2 )Anneiled
96422

No anneiled
82
83

critical temperatures and critical current were greatly
improved by annealing at the temperature of 723 K
for 24 hours in the the high purity Ar atmosphere.
Currently, the Ag substrates of the induction ring andshielding ring are being coated and molten. Furthermore, a large quartz glass container used for the annealing is also being fabricated.
This work is supported by Japan Society for
the Promotion of Science KAKENHI Grant Number 19H04403.

Shielding Ring

(Coated Bi2212 on Ag substrate)

HTc SQUID

Induction Ring

(Coated Bi2212 on Ag substrate)

References
1) T. Watanabe et al., Proc. 2010 Beam Instrumentation
Workshop (BIW10), Santa Fe, US, 2010-9, p. 523.
2) T. Watanabe et al., Proc. 4th International Beam
Instrumentation Conference (IBIC2015), Melbourne,
Australia, 2015-9, p. 590.
3) T. Watanabe et al., Proc. 13th Annual Meeting of Particle Accelerator Society of Japan, 2016-8, p. 1127.

High permeability
magnetic coreFig. 1. A new scheme based on a direct coupling between
an induced magnetic ﬂux and the HTc SQUID.3)∗1-4

RIKEN Nishina Center- 70 -

Ⅱ-8. Accelerator
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of auto-tuning system using Bayesian optimization
for ion optics in primary beam line with 26 electric nA Kr beam
T. Nishi,∗1 N. Fukuda,∗1 E. Iwai,∗2,∗3 H. Maesaka,∗2 Y. Shimizu,∗1 T. Sugimoto,∗2,∗3 T. Sumikama,∗1 andA. Uchiyama∗1

∗1
∗2
∗3

15

F3Y [mm]80

σh: 1.5 mm

1070

σv: 0.7 mm

5

60
50

0

40
30

−5

20

−10
−15
−15

10
−10

−5

0

5

F3X [mm]1015

Beam width (rms) [mm]H2_F3XY

0

8
6
4
2
0
0

RIKEN Nishina Center
RIKEN SPring-8 Center
Japan Synchrotron Radiation Research Institute- 71 -

220
200

σv: 0.8 mm

180
160
140

0

120
100

−5

80
60

−10

40
20

−15
−15

−10

−5

0

5

F3X [mm]

4

6

8

10

10

15

0

DMT2 DMT3DMT1Beam width (rms) [mm]240

σh: 1.1 mm

52

location number with PF

15
10

DMT2 DMT3

DMT1

10

H2_F3XY

F3Y [mm]

We started the project to introduce the auto-tuning
system of the accelerator facility to RIBF as reported
last year.1) As a ﬁrst step in this project, we adopt anauto-tuning program using sequential learning based on
Bayesian optimization2) to the beam line optics from the
SRC to BigRIPS ﬁrst production target F0, so-called TCourse.
A test experiment for the project was conducted in
May 2022 with Kr36+ beam to develop a new method tomeasure beam intensity and beam spot simultaneously
for high-intensity beams. In the method, the phase ellipse and intensity of the primary beam are measured
using BigRIPS nominal detectors. Because the direct
measurement with these detectors limits the intensity ofthe primary beam, the charge-converted particles created by the 1 mm-thick Be target at F0 are measured
by downstream detectors. This method enables to measure, for example, approximately 10 kcps Kr34+ beamat F3 as an indicator of a primary 30 electric nA Kr36+
beam.
In the experiment, Kr34+ was selected by the F1 slit
and measured by PPACs and a scintillator at F3. The
beam intensity was set to approximately 0.001 electric nA for the 5 diﬀerent optical conditions to compare with the nominal method, and spot images wereacquired with the viewer target at F0. As a result, they
showed good agreement and we conﬁrmed the measured
values by F3 detectors were good indicators for the primary beam. Next step, we adjusted the optics of the
T-course using the developed indicators. In the opticalsystem tuning, it was necessary to ﬁnish the measurement and evaluation in a few tens of seconds for each parameter sets. We converted PPAC data into trajectories
and beam widths within a few seconds using the newly
developed BYACO3) system and passed the data to the
optimization program via EPICS. Finally, we optimized
the currents of doublet quadrupole magnets QDT11ab and QDT12a-b with 26 electric nA Kr36+ primarybeam to maximize the scintillator count rate and minimize the beam widths at F3. Left panel of Fig. 1 shows
beam spot measured by F3 PPACs before (left top) andafter (left bottom) optimization. As shown in the ﬁgures, the horizontal beam widths are reduced from 1.5
to 1.1 mm (rms) at F3. The transmission eﬃciency was
also measured for each optics with the Faraday cup at
G01 and beam dump inside the D1 magnet, and it conﬁrmed that both values agree within the errors. Graphs
in the right panel of Fig. 1 show measured and calculated beam widths at the location of proﬁle monitors in

10
8
6
4
2
0
0

2

4

6

8

location number with PF

10

Fig. 1. (Top) Before optimization. (Bottom) After optimization. (Left) beam spot of Kr34+ measured by F3 PPACs.
(Right) Beam widths at the location of proﬁle monitors. Red (blue) marks correspond to horizontal (vertical) beam widths, and circle (square) marks correspondto the data measured by proﬁle monitors (calculated by
the simulation).

T-Course. The location 10 indicates F0. The calculation is based on the measured beam phase ellipse at F3.
As shown in the ﬁgures, the measured and calculated
values are in good agreement, except the vertical beamwidths between DMT1 and DMT2. These calculations
also show the optimized ion optics realized the smaller
beam spot at F0.
In conclusion, we developed a new method to measure beam spot and intensity simultaneously with highintensity primary beam. With the method we optimized
ion optics in T-Course and reduce beam spot size at F0,
keeping beam transmission eﬃciency. This new method
using BYACO opens the possibility of optimizing theparameters of the beam lines using not only the beamspot, but also the signal of any downstream detector(e.g., the signal-to-noise ratio of secondary particles) as
an indicator. We are developing a new algorithm withsafe regions to apply this method for the higher intense
primary beam.
References
1) T. Nishi et al., RIKEN Accel. Prog. Rep. 55, 66 (2021).
2) E. Iwai et al., Proc. PASJ2021, WEOB02 (2021).
3) T. Sumikama et al., RIKEN Accel. Prog. Rep. 54, 82(2020).

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Development and test operation of the prototype of the new beaminterlock system for machine protection of RIBF
M. Komiyama,∗1 M. Fujimaki,∗1 A. Kamoshida,∗1,∗2 M. Hamanaka,∗3 M. Nishimura,∗3 R. Koyama,∗3
K. Kaneko,∗3 A. Uchiyama,∗1 and N. Fukunishi∗1
Continuing from 2021, we are developing a new beaminterlock system (BIS) for machine protection based on
CompactRIO1) (hereafter, cRIO-BIS), a product by National Instruments, as a successor system to the BIS,2)
which has been in operation since 2006. We set up a prototype using one CompactRIO and one expansion chassis
with I/O modules and developed the logic for digital input signals. The prototype signals for both a beam chopper and a beam stopper (Faraday cup) immediately after
receiving an alert signal. Details are shown in Fig. 1.
Chopper set/reset signal from the console,
1. Input alarm signal
users, devices, etc.
3. Order to work a beam chopper via
2. Order to work a beam
dedicated hardwire#1 (NI-9149)#5 (cRIO-9056)
chopper

FPGA (on chassis)

BIS Logic Unit (DI)BIS Logic Unit (DI)BIS Logic Unit (DI)BIS Logic Unit (DI)

Relay-DO

BIS Logic Unit (DO)BIS Chopper Unit (TTL)BIS Chopper Unit (DO)CPU
FC status from EPICS

BIS Chopper Unit (DI)

Chopper output
request information

FPGA (on chassis)

2. Order to set Faradaycup (FC)

EPICS-LAN
FC status Set interlock pattern/ Monitor signals
4. Output a signal to a beam chopper.
It immediately deflects a beam justbelow the ion source.

N-DIM FC-H31

3. Insert FC installed upstream of the
problematic component

N-DIM FC-H72

Fig. 1. Hardware conﬁguration and process ﬂow in the cRIOBIS prototype.

The CompactRIO system has three layers for implementing logic for signal control: a ﬁeld-programmablegate array (FPGA) layer, which is the most reliable andcapable of the fastest signal processing, a real-time OS(RT-OS) layer that is positioned in the upper layer of
FPGA and communicates with FPGA, and a WindowsOS layer that is positioned in the upper layer of themand communicates with them. FPGA is implemented on
both CompactRIO and its expansion chassis, and RTOS is implemented on CompactRIO. The goal of cRIOBIS is to stop the beam within 1 ms by outputting asignal to the beam chopper from an alert signal input.
Thus, interlock logic for signal input/output is implemented on the FPGA. However, signal condition setting
and monitoring do not require the same speed as interlock logic. Thus, they are implemented on the RT-OSand controlled by using experimental physics and industrial control system (EPICS)3) by setting up an EPICS
server on the RT-OS.
Based on the operational experience of the BIS, cRIOBIS implements two types of logic units; BIS Logic Unit
∗1
∗2
∗3

RIKEN Nishina Center
National Instruments Japan Corporation
SHI Accelerator Service Ltd.

(BLU) and BIS Chopper Unit (BCU). The BLU judges
conditions such as mask and holding time for alert signal
input and sends a signal to the BCU to request a signal
to the beam chopper via dedicated hard wire. The BCU
compares the input signal from the BLU and the insertion status of the Faraday cup and outputs a signal to thebeam chopper. Since the BCU is designed to perform not
only the function of BIS but also the role of the existing
chopper signal control panel (it will be decommissioned
in the future), it also receives signals from the console’s
manual switches and user’s devices and outputs signal tothe beam chopper.
After developing the prototype in the control room,
its two stations were installed next to RIBF-BIS station 5 in the computer room of the Nishina Building andnext to RIBF-BIS station 1 in the power supply room 2of the RIBF building. The signal wiring was performed
during the summer maintenance period. Since the prototype was planned to be tested in a part of the RIBF-BIS
consisting of 5 stations, we connected the input signals
into the prototype in parallel with the RIBF-BIS andevaluated its performance. The GUI for signal settingsand prototype monitoring has been developed using theControl System Studio (CSS)4) of EPICS, and the log
system has been developed using the system in RILACoperation.5)
After installing the prototype, we measured the response time of the system with alert signals generated
experimentally from an actual component and obtained
a result of approximately 250 µs (between 229.0 µs to260.0 µs). This is consistent with the system’s responsetime measurements using test input signals in the control
room. Furthermore, it was conﬁrmed by the test that the
response time could be reduced to less than 200 µs by
adding a pull-up circuit to the signal input/output part.
Since the response time of RIBF-BIS measured using thesame signal was approximately 15 ms, we were able todevelop a system that is approximately 100 times fasterthan the BIS.
We have started the test operation of the prototype
during the beam service times scheduled in the latter
half of the ﬁscal year 2022. Some minor corrections werenecessary; however, no major defects were observed.
References
1) CompactRIO,
https://www.ni.com/ja-jp/shop/compactrio.html .
2) M. Komiyama et al., RIKEN Accel. Prog. Rep. 39, 239(2006).
3) EPICS, https://epics.anl.gov/ .
4) CSS, http://controlsystemstudio.org/ .
5) A. Uchiyama et al., Proc. 18th Annual Meeting of Particle
Accelerator Society of Japan (2021), p. 532.

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Ⅱ-8. Accelerator
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Activation of temperature control in the RILAC cooling water
K. Yamada,∗1 M. Tamura,∗2 A. Yusa,∗2 and N. Sakamoto∗1∗1∗2

control of the heat exchanger bypass valves in the resonator and irradiation vault systems was enabled, andboth systems were maintained within ±0.2◦ C.
The SRILAC system was originally a cooling system for the RILAC booster, but the automatic controlof the ﬂow control valve had been disabled since thewater leak in 2009. The control panel was modiﬁed
to enable automatic ON/OFF control of two fans alternately, and automatic control of the primary temperature control valve was enabled. As a result, thetemperature could be controlled to ±0.1◦ C.
The vacuum pump system used a closed cooling
tower. Previously, the system froze during the cold
winter, requiring repair. Thus, the control panel was
modiﬁed, and a temperature controller was added.
Currently, the temperature is controlled at 23 ± 2◦ C,
and there is no longer any concern about over-cooling.
Figure 1 shows an example of one day trend for rf
voltage and phase in the RILAC resonators. The rf
stability is dramatically improved after activating thetemperature control, contributing to a further intensebeam supply and increased availability.
RF1 voltage

RF2 voltage

RF1 phaseRF2 phase

Water temperature
29.0

1.00202021/06/05
Fluctuation [normalized]

1.001528.5
28.0

1.001027.5
1.000527.0

1.000026.5

0.999526.0
25.5

Temperature [Υ]Fluctuations in cooling water temperature have asigniﬁcant impact on the accelerator. For example, achange in water temperature deforms the cavity resonator of the accelerator and changes its resonant frequency, resulting in a slight drift in rf voltage andphase despite feedback control. This aﬀects the beam,causing beam loss and making it diﬃcult to maintain ahigh-intensity beam. Therefore, we decided to activate
the temperature control of the cooling water system of
RILAC to realize a high-intensity beam and improveavailability.
The cooling water of the RILAC is roughly divided into the ion source system, RFQ1) system, RILAC2) main system, RILAC booster3) /SRILAC4) system, and vacuum pump system. Except for the vacuum system, the secondary cooling water was cooledin the cooling tower, and the primary cooling water,which recovers heat from the load, was cooled througha heat exchanger. Some systems had ﬂow control
valves for temperature control, but the majority ofthem were disabled. In addition, all the fans in thecooling tower were constantly rotating, and the temperature of the secondary water ﬂuctuated greatly depending on the condition of the outside air. As a result,
the temperature of the primary water changed several
degrees in one day.
The ion source system was originally temperaturecontrolled, but the cooling tower fan was rotated constantly. This secondary water was also used for the
RILAC drift tube cooling system, and the temperature drop in winter caused a vacuum leak from thedrift tube, resulting in a severe discharge. Therefore, atemperature controller was added on the control panel
to automatically turn fans ON/OFF at 24 ± 1.5◦ C.
The RFQ system had a heat-exchanger bypass valve
on the secondary side, which was sticking and unusable. The control panel was modiﬁed to add a primaryand secondary temperature controller, and the bypass
valve was replaced with a new one. The cooling tower
fan is now automatically controlled ON/OFF at 23 ±1◦ C, and the primary temperature automatically controls the bypass valve to keep at about ±0.1◦ C.
The secondary cooling water in the RILAC main system cools the resonator system, ampliﬁer system, andirradiation vault system as the primary side. The number of cooling tower fans can be controlled by adding
a temperature controller and rewriting the logic controller program by automatically turning them on andoﬀ individually. In addition, the fans are activated insequence to reduce damage due to startups. Automatic

0.999025.0
0.998524.5

0.998024.0

0:00:00 2:00:00 4:00:00 6:00:00 8:00:00 10:00:00 12:00:00 14:00:00 16:00:00 18:00:00 20:00:00 22:00:00 0:00:00

RF1 voltage

RF2 voltage

RF1 phaseRF2 phase

Water temperature
29.0

1.00202023/01/23

28.5
28.0

1.001027.5

1.000527.0

1.000026.5

0.999526.0

25.5

Temperature [Υ]Fluctuation [normalized]

1.00150.999025.0

0.998524.5

0.998024.0

0:00:00 2:00:00 4:00:00 6:00:00 8:00:00 10:00:00 12:00:00 14:00:00 16:00:00 18:00:00 20:00:00 22:00:00 0:00:00

Fig. 1. One day trend of rf voltage and phase in the RILAC
resonator no.1 and no.2 before (upper panel) and after(lower panel) stabilizing the water temperature.

References
1) O. Kamigaito et al., Rev. Sci. Instrum. 70, 4523 (1999).
2) M. Odera et al., Nucl. Instrum. Methods Phys. Res. A
227, 187 (1984).
3) O. Kamigaito et al., Rev. Sci. Instrum. 76, 013306(2005).
4) K. Yamada et al., Proc. SRF2021, (2021), p. 167.

RIKEN Nishina Center
SHI Accelerator Service Ltd.

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Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

2022 operational report of the Nishina RIBF water-cooling system
T. Maie,∗1 K. Kusaka,∗1 Y. Watanabe,∗1 M. Kidera,∗1 K. Kobayashi,∗2 J. Shibata,∗2 K. Yadomi,∗2
M. Oshima,∗3 and H. Shiraki∗3
In 2022, the Nishina and RIBF cooling systems wereoperated for a slightly longer duration than the accelerator. The RIBF cooling system was operated for approximately 70 days, excluding the time of installation
which was carried out continuously. Other cooling systems by Nishina (AVF standalone, AVF + RRC, AVF+ RRC + IRC, and RILACII + RRC) were operated
for approximately less than six months. Except forsome minor problems, the cooling systems operated
stably, and there were no long-term shutdowns of theaccelerator. Complications regarding the SRC vacuum
were experienced during the second half of the RIBF
operating time, resulting in a cooling system operatingtime that was less than a year.
The minor problems that occurred are listed below.

Fig. 1. RIBF water-cooling pump maintenance (Periodic
maintenance).

(1) Cooling tower fan failure(2) Water leakage from the joint of the cooling pipe
(3) Decline in purity of cooling water due to waterleakage(4) Cooling water pump motor bearing failure(5) Equipment shutdown caused by momentary
voltage drop due to lightning (3–4 times a year)
The afore-mentioned problems occur at approximately
the same frequency every year. We experienced only
minor complications because of proper periodic maintenance. Figure 1 shows a photograph of the periodic maintenance of the RIBF cooling pump. Figure 2 shows a photograph of the disassembly processof the cooling pump bearing. Periodic maintenance isplanned as usual for the long-term suspension of accelerator operation in summer and winter. See theprevious for details on the maintenance.
The annual cooling-equipment maintenance budget
is extremely low. Maintenance is performed annually
within the budget; however, the deterioration of the facilities is inevitable. The commodities and spare partsof the water-cooling pumps that have been used for the
past 15 years are not produced anymore and are difﬁcult to obtain. Aging cooling equipment is not only
a causes of failure, but also one of the causes of beam
instability in accelerators. Managing the costs of maintenance is an important concern for the future.

∗1
∗2
∗3

Fig. 2. Pump bearing section disassembly (Periodic maintenance).

Reference
1) T. Maie et al., RIKEN Accel. Prog. Rep. 55, 65 (2022).

RIKEN Nishina Center
SHI Accelerator Service Ltd.
Nippon Air Conditioning Service Co., Ltd.

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Ⅱ-8. Accelerator
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Relationship between instantaneous voltage drops at RIKEN andinﬂuence on transmission power lines
M. Kidera,∗1 T. Maie,∗1 S. Watanabe,∗1 E. Ikezawa,∗1 Y. Watanabe,∗1 and O. Kamigaito∗1
A stable supply of electric power is very important
for accelerator facilities. Power outages and momentary voltage drops are unwelcome not only because
they can shut down equipment but also because they
can damage it. In addition, power problems occurring
during the delivery of high-intensity, high-energy ion
beams to the user are serious because they can cause ashift in the beam trajectory and lead to serious accelerator failures. The Nishina Center has a gas-turbinetype cogeneration system (CGS)1) in addition to thepower supply an external power company. If there is arisk of a lightning strike, the CGS is activated to power
the chillers that use liquid He. Information on lightning strike hazard is provided by the power company,
which can be found on the internet. In this study,
we report the correlation between the instantaneousvoltage drops at RIKEN and inﬂuence on transmission
power lines. Data on the inﬂuence on the power lines
were provided by TEPCO Power Grid and data on the
instantaneous voltage drop at RIKEN were provided
by RIKEN’s Facilities Division.
Electricity is generated by nuclear, thermal, andhydroelectric power plants and transmitted via highvoltage transmission lines. These power plants are located far from RIKEN. The transmission lines fromthese power plants are networked to achieve a stable
power supply. Transmission from the power plants istransformed in the sequence 500 kV, 275 kV, 154 kV,

66 kV, and 22 kV along the transmission path, andwired to various residential and factory areas. The
voltage of transmission line drawn into a factory or acommercial facility is determined by the electric power
used by the facility. Electricity delivered to RIKEN at
66 kV from the power company, converted to 6600 V
at a substation on site, and then transformed to 400 V
and 200 V at a voltage transformer in the center. Table 1 shows the number of instantaneous voltage drops
at RIKEN from 2017 to 2022, categorized according
to the inﬂuence on power lines to each transmission
line. Instantaneous voltage drops at RIKEN due tolightning strikes on the 500 kV power lines accountfor approximately 60% of the total, and approximately
79% if statistics are taken from lightning strikes alone.
Much of the 500 kV power line network is located close
to the power plant and far from RIKEN. Preparation
for instantaneous voltage drops due to lightning strikes
requires attention to not only the nearby lightning advisories, but also to the lightning strikes occurring in
the neighboring prefectures.
Reference
1) T. Fujinawa et al., J. Part. Accel. Soc. Jpn. 8, 18 (2011).

Table 1. The number of instantaneous voltage drops at RIKEN from 2017 to 2022, categorized the inﬂuence
on power lines to each transmission line.

Transmission line voltage∗1

Lightning strike

Accident

500 kV15

1

275 kV

1

1

66 kV

1

unknown

2

RIKEN Nishina Center- 75 -

2

Other

2

Ⅱ-8. Accelerator

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Status of vacuum pumping systems in accelerator facilities
Y. Watanabe,∗1 M. Fujimaki,∗1 Y. Higurashi,∗1 E. Ikezawa,∗1 O. Kamigaito,∗1 M. Kidera,∗1 T. Nishi,∗1
S. Watanabe,∗1 K. Yamada,∗1 M. Nishida,∗2 K. Oyamada,∗2 J. Shibata,∗2 K. Yadomi,∗2 and A. Yusa∗2
A vacuum pumping system in the RIBF accelerator facility comprises cryopump (CRP) systems,
turbo-molecular pump (TMP) systems, rough pumping systems (mechanical booster pump + rotary pump[RP]), additional chamber pumping systems, and subpumping systems.1) In addition, module-type vacuum
gauges (total pressure gauge [TPG] controller combined with two gauges) are used in almost all vacuum
pumping systems. In this study, we report the malfunction status of a vacuum pumping system encountered in 2022. Table 1 lists the number of malfunctionsin the vacuum pumping systems from 2018 to 2022.
The vacuum pumping systems were stable to maintainand manage in 2021 and 2022, and most malfunctionsof each unit were less frequent than in other years.2)
There was only one CRP (pump) malfunction, suchas abnormal noise, vibration, and helium leakage, andthe reason for this decrease is unclear. Furthermore,
only one CRP compressor in the SRC malfunctioned
due to a high environmental radiation dose. The reason for this decrease is due to the use of the existing old CRP compressor (model: C30V), which hasa higher radiation resistance than the new CRP compressor (model: C30VRT), as long as possible. However, because the existing C30V is fewer and has been
discontinued by the manufacturer, we plan to relocate
eight of 13 compressors to a location far from the region of high environmental radiation (from the SRCnortheast area to the SRC-south area) in 2023.2) Two
new CRP compressors (model; C30VRT and F-50L)
were purchased as spare units due to the existing discontinued CRP compressors (model; C30V, CRC-874,
and P-875CA) of the AVF, SRC, RRC, fRC, and IRC.
In the CRP system of AVF, RRC, and SRC, some helium leakages have occurred in some ﬂexible hoses andcouplings which were repaired by installing new parts.
Only one TMP (pump) and one power supply havemalfunctioned due to age-related deterioration, suchas abnormal noise, vibration, and circuit board failure,
and the reason for this decrease is also unclear. In the
Table 1.
CRP

a

TMP b
RP c
TPG d

Pump
Compressor
Pump
Power supply
Pump
Controller
Gauge

update of large TMP systems (5000 L/s), we plan toreplace the large TMP of the RILAC No.4 tank with aset of medium TMPs (800 L/s, 1100 L/s, and 2400 L/s)
in 2023.
Five malfunctioned RPs were also caused by agerelated deteriorations. Some oil leaks in the small RPs
were repaired as usual by installing new O-rings andseals.
Age-related deteriorations also caused four malfunctioned TPG controllers. There were no malfunctioning TPG controllers when power was restored following an electrical power outage in August and October
2022.2) Three malfunctioned gauges were replaced byspare units due to a contamination of the sensor head.
Almost all vacuum leaks at the RIBF were causedby age-related deterioration and were repaired by installing new parts, applying a repair material, or rewelding. For example, multiple water leaks from thewater-cooling parts in the RRC or SRC cavities were
repaired by re-welding. A vacuum leak of stainlessbellows between the resonator No.2 cavity and a mainchamber of the S-sector magnet in the RRC occurred
for the ﬁrst time in 2014 and was repaired for the thirdtime with a sealing agent. Vacuum leaks of multiple
ﬂange welds in the AA6 chamber, installed in the fRCIRC beam transport line, and in the RILAC cavities
No.2 and No.6 were also repaired with a sealing agent.
Faraday cup of the C21 chamber, a slit of A01 chamber and an O-ring of the AVF-RF No.2 were replacedwith spare units or new O-ring. Finally, a vacuum leakdue to beam loss damage occurred at a beam duct ofthe magnetic deﬂection channel No.3 in the SRC in
December and is still under consideration.
References
1) Y. Watanabe et al., RIKEN Accel. Prog. Rep. 50, 154(2016).
2) Y. Watanabe et al., RIKEN Accel. Prog. Rep. 55, 67(2021).

Number of malfunctions from 2018 to 2022.

Number of units

2018

2019

2020

> 80

4

6

7

> 138

3

8

4

> 146

5

3

7

> 160

4

6

9

2021
6
8
1
4
1
5
7

2022
1
5
1
1
5
4
3

a Includes a compressor. b Includes an attached power supply. c Excludes an oil leak. d Includes a controller, Pirani, and cold cathode gauge.

∗1∗2

RIKEN Nishina Center
SHI Accelerator Service Ltd.

- 76 -

9. Instrumentation

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of an automatic particle identiﬁcation system for the
BigRIPS separator
Y. Shimizu,∗1 N. Fukuda,∗1 H. Takeda,∗1 H. Suzuki,∗1 M. Yoshimoto,∗1 Y. Togano,∗1 T. Sumikama,∗1
H. Baba,∗1 and K. Yoshida∗1
We are developing a fully automatic system forradioactive-isotope (RI) beam production based on our
technological developments and experiences to reduce
the operation time. In the present study, we aimed toautomate particle identiﬁcation (PID) for RI beams.
PID was performed event-by-event using the ∆ETOF-Bρ method to determine the mass-to-charge ratio A/Q and atomic number Z of RI beams.1) PID
was conﬁrmed by measuring the delayed γ-rays emitted from isomers. A PID analysis has been performed
with the following procedure:
1. Find the isomers among RI beams,
2. Detect the peak energies from the delayed γ-ray
spectra of the isomers,
3. Identify the isomers by comparing the detected γ
energies with the known isomeric γ energies, and
4. Determine the calibration parameters for A/Q
and Z.
This analysis procedure was automated using the BYACO ecosystem.2) The information on the isomeric
nuclei observed at RIBF was stored in a relational
database (RDB) based on Microsoft Access 2010.3)
To use this information in the BYACO ecosystem, theRDB was transferred to a PostgreSQL database on aLinux server.
The automatic PID system was tested online during
the 132 Sn-beam production required for MS-EXP2204.4) Figures 1(a) and 1(b) show the PID plots without
and with the delayed γ coincidence, respectively. The
observation of isomers enhanced the fraction of blobsin Fig. 1(b) compared with that in Fig. 1(a). PID gates
for the enhanced blobs were created and the delayed
γ-ray spectra were obtained, as shown in Fig. 2. The
isomers were identiﬁed by scanning the RDB for themeasured peak energies, e.g., blob No. 13 was identiﬁed as 132 Sn. The calibration parameters for PID
were determined using A/Q and Z of the identiﬁed
isomers. This automatic PID system was successfully
demonstrated. As a result, the operation time became
shorter than that of conventional manual tuning by
15 min.
The current system requires the RI-beam physicist
to conﬁrm that suﬃcient data have been acquired toobtain some γ-ray spectra. In future work, we will
fully automate PID for RI beams.

∗1Fig. 1. Z versus A/Q PID plots (a) without and (b) withthe delayed γ coincidence. The automatically generated
gates for the isomers are labeled as 1: 132 Te, 2: 134 Te,
3: 135 Te, 4: 129 Sb, 5: 130 Sb, 6: 131 Sb, 7: 136 Sb, 8: 126 Sn,
9: 127 Sn, 10: 128 Sn, 11: 129 Sn, 12: 130 Sn, and 13: 132 Sn.

Fig. 2. Delayed γ-ray energy spectrum in coincidence withblob No. 13, which was found to be 132 Sn using theautomatic PID system.

References
1) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).
2) T. Sumikama et al., RIKEN Accel. Prog. Rep. 54, 82(2021).
3) Y. Shimizu et al., RIKEN Accel. Prog. Rep. 47, 166(2013).
4) Y. Shimizu et al., in this report.

RIKEN Nishina Center- 77 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Introduction and performance evaluation of a new data acquisition
system for germanium detectors
H. Takeda,∗1 H. Baba,∗1 N. Fukuda,∗1 H. Suzuki,∗1 Y. Shimizu,∗1 M. Yoshimoto,∗1 Y. Togano,∗1 andK. Yoshida∗1
Isomer tagging is an essential technique for unambiguous particle identiﬁcation (PID) in BigRIPS1) andis achieved by detecting characteristic γ rays emitted
from known short-lived nuclear isomers. Currently, twoclover-type high-purity germanium (Ge) detectors areused for this purpose. Data acquisition (DAQ) for
Ge detectors has traditionally been performed with a
CAMAC-based system. However, many CAMAC modules are aging and becoming diﬃcult to maintain due
to discontinued production. Further failure of the critical modules could interfere with the isomer tagging.
Therefore, considering an alternative DAQ system has
been an urgent issue recently.
Mesytec MDPP-162) is a promising candidate for the
new DAQ system. It is a VME-based, 16-channel digital pulse processor with a fast high-resolution timeand amplitude digitizer. Input signals are ﬁrst ampliﬁed, ﬁltered, and then digitally reconstructed ina hardware component, followed by detailed analysis
in a digital signal processing unit implemented in aﬁeld-programmable gate array (FPGA). Among several FPGA software modules available for the MDPP16, the standard “SCP” module suits our purpose. It
delivers timing and amplitude information for standard charge-integrating preampliﬁer signals with 16-bit(64k) resolution. It can replace all the conventional
shaping ampliﬁers, peak-sensitive ADCs, timing ﬁlter
ampliﬁers, constant fraction discriminators, and TDCs.
First, we examined the ADC and TDC performanceof the MDPP-16 SCP. The integral non-linearity (INL)of ADC was less than 0.1%, while the diﬀerential nonlinearity (DNL) of ADC was less than 4% over the 20%–90% range of full scale. The INL and DNL of TDC wereless than 0.001% and 0.03%, respectively. Time slewing
with respect to the pulse height was less than 0.4 ns.
These performance values were comparable to or better
than the current system.
Figure 1 shows a γ-ray spectrum of a 60 Co source
measured with the MDPP-16 SCP by the Ge detector
used in the actual isomer tagging.
FWHM resolution of the 1332-keV peak was typically
4.7 keV. This value was mainly due to the accumulationof radiation damage to the Ge crystals over the years
and was the same as that measured with the current
system.
The isomeric γ-ray measurement using the MDPP16 SCP was performed during the BigRIPS tuning thisautumn. Figure 2 shows an atomic number (Z) versus mass-to-charge ratio (A/Q) PID plot for a 52 Cacentered radioactive isotope (RI) beam.
∗1

RIKEN Nishina Center- 78 -

Fig. 1. γ-ray spectrum of a 60 Co source measured with the
MDPP-16 SCP.

Fig. 2. Z versus A/Q PID plot of the 52 Ca-centered RI
beam. Delayed γ-ray energy spectrum of the 54 Sc isomer
is overlaid in the upper right corner.

The delayed γ-ray energy spectrum of the isomeric
nucleus 54 Sc is overlaid in the upper right corner. The
presence of a distinct 110-keV peak indicates that the
MDPP-16 SCP can be used for isomer tagging.
Finally, we examined long-term stability, which isalso important for practical operations. The energy calibration was stable within 0.5 keV over several days if
no setting was changed. However, when we changed thesettings, such as thresholds, the calibration was occasionally shifted from a few keV to a maximum of 10 keV.
Based on oscilloscope observations, it is suspected thatthe baseline may shift when the settings are changed.
A detailed investigation is in progress. While this issue
must be resolved, the MDPP-16 SCP has the suﬃcientperformance required for the new DAQ system of the
Ge detectors. We plan to replace the current CAMACbased system with the new system as soon as possible.
References
1) N. Fukuda et al., Nucl. Instrum. Methods Phys. Res. B
317, 323 (2013).
2) https://www.mesytec.com/products/nuclear-physics/
MDPP-16.html .

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Conceptual design of new high-power beam dump for BigRIPS
Y. Togano,∗1 N. Fukuda,∗1 H. Suzuki,∗1 Y. Shimizu,∗1 H. Takeda,∗1 M. Yoshimoto,∗1 and K. Yoshida∗1
A new high-power beam dump situated at the exitof the ﬁrst dipole magnet (D1) in the BigRIPS separator has been designed to absorb a 2 particle µA 238 U
beam at 345 MeV/nucleon. The BigRIPS separator isequipped with beam dumps located both inside and at
the exit of the D1 magnet to intercept unreacted beams
resulting from primary beam + production target reactions at the focal plane F0. In the near future, the
RIBF intends to utilize a 2 particle µA 238 U primarybeam, which is 30 times more intense than the current 238 U beam, in order to produce a greater variety
of exotic nuclei. However, the existing beam dump at
the exit of the D1 magnet (hereafter referred to as theexit-beam dump) is incapable of safely absorbing suchan intense beam due to insuﬃcient cooling power. For
performing experiments with 2 particle µA 238 U beam,
a new high-power exit-beam dump, that utilizes a rotating water-cooled copper drum, has been designed.
The schematic depiction of the newly proposed exitbeam dump is illustrated in Fig. 1. The drum-shaped
beam dump, measuring 300 mm in diameter and
350 mm in depth, rotates about its central axis to
distribute heat and improve radiation damage resulting from the intense beam. The dump is made of acopper alloy, speciﬁcally Cu-Cr-Zr, and is equippedwith 72 screw tubes (M8 tapped) to serve as watercooling channels.1) The water ﬂowed in the coolingchannels is pressurized at 1 MPa and runs at a velocity of 10 m/s, ensuring a high rate of heat transfer between the cooling water and the copper alloy. This M8
tapped cooling channels have already been equipped
for the present exit beam dump.2) The distance fromthe surface of the dump to the center of each coolingchannel is 14 mm, and the pitch of the cooling channels
is 12.2 mm. The rotational frequency of the dump isassumed to be suﬃcient to achieve a uniform temperature distribution along the circumference of the dump.
The cooling capacity of the dump is evaluatedthrough ﬁnite element method simulation utilizing the
ANSYS code. The results of the simulation are appraised against the following criteria:2) the maximum
temperature of the dump should be less than 350◦ C tomaintain the radiation hardness of the dump, and theheat ﬂux at the surface of the cooling channels mustbe less than the critical heat ﬂux (55 MW/m2 ) for stable cooling of the dump. It is known that copper alloy
keeps good radiation hardness at temperatures below
400◦ C. Above the critical heat ﬂux, the heat transfer
rate at the cooling channel abruptly decreases as thesurface of the cooling channel becomes covered withvapor generated by vigorously boiling cooling water.
In the simulation, it is assumed that a 2 particle µA
238
U beam (Q = 86+ ) at 345 MeV/nucleon is directly
impinged on the dump as illustrated in Fig. 1a). The
beam spot on the dump is of an elliptical shape due
to overfocus by the D1 magnet. The ratio of magnetic
rigidities between the 238 U beam and a beam following the central trajectory of the D1 magnet is assumed
to be 0.85. The range of the 345 MeV/nucleon 238 U
beam in copper alloy is 3.2 mm.
Figure 1b) illustrates the calculated temperature
distribution on the surface of the dump upon the impingement of the 2 particle µA 238 U beam. The maximum temperature of the dump is 159◦ C and the maximum heat ﬂux at the surface of the cooling channel
is 5.4 MW/m2 . These values are below the allowabletemperature and the critical heat ﬂux, indicating thatthe new dump can safely absorb the 2 particle µA 238 U
beam. The detailed design of the new exit beam dump
is currently underway.
References
1) J. Boscary et al., Fusion Eng. Des. 43, 147 (1998).
2) K. Yoshida et al., Nucl. Instrum. Methods Phys. Res. B
317, 373 (2013).

Fig. 1. a) Schematic view of the new exit beam dump. b)
Caluculated temperature distribution on the surface ofdump impinged by a 2 particle µA 238 U primary beam.
∗1

RIKEN Nishina Center- 79 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Energy-degraded beam on BigRIPS F0
H. Otsu,∗1 N. Fukuda,∗1 T. Nishi,∗1 and T. Sumikama∗1
Uranium (and Xe, Kr) beams, which are accelerated up to the SRC, have a ﬁxed beam energy of
345 MeV/nucleon because ﬁxed-frequency accelerators
are operated upstream. If a lower energy beam is required, the beam energy would be lowered with material as an energy degrader at the ﬁrst stage of BigRIPS. Subsequently, the lower energy beam would bedelivered into the downstream beamline. The energydegraded beam would be transported to F2 or F3,
where reaction targets would be placed. The disadvantages of the method are: 1) Transport of a relatively
intense primary beam to F2 or F3 is required for themeasurement of the reaction cross section, which might
be subject to radiation shielding limitations. 2) Reaction products should be separated using downstreamof F3 in BigRIPS, which requires a completely diﬀerent
approach compared to the measurement of production
cross sections at 345 MeV/nucleon. This in turn mightlead to large systematic errors.
Based on these reasons, the possibility of providing
energy degraded beam to BigRIPS F0 was investigated
and tested. A primary beam transport beamline is located from the G01 port to BigRIPS F0 downstream of
the SRC exit. At an intermediate beam proﬁle monitor
port T11 beam can focus in both X and Y directions.
Therefore, if this type of transport optics are used andan energy degrader material are located at T11, it isexpected that the primary beam can be transported
to the F0 focal plane without increasing phase spaceof the primary beam largely. Figure 1 shows the calculated transport from T11 to the F0 focal plane. In
fact, this transport method has been previously usedin dispersion matching experiments1) for veriﬁcationof dispersion matching. Conversely, an energy degrade
material has never been placed here before. This test
was the ﬁrst attempt to investigate the transport ofenergy-degraded primary beam to BigRIPS F0.
SRC-BIGRIPS

BEAM PLOTThe energy degrader plate was inserted from oneof the ports at T11. It made of aluminum with 8
steps, each with a thickness ranging from 1.7 mm
to 9.3 mm. After passing through each steps, uranium primary beam with 345 MeV/nucleon was degraded into 300, 250, 200, 150, 100, 75, 50 and
25 MeV/nucleon. When the energy degrader plateis withdrawn, the 345 MeV/nucleon U beam passes
unchanged with the 86+ charge 345 MeV/nucleon U
beam passes unchanged with the 86+ charge state. The
beam is then transported to F0 by adjusting the magnetic ﬁeld of the dipole magnets DMT2,3 to match themagnetic rigidity required for the 86+ beam.
The U beam that has passed through the energy
degrade plate has a dispersed charge state, and it isdeﬂected by the DMT2 and DMT3 magnets from T11
and transported to F0 as shown in Fig. 1. It can beobserved that a beam with a charge state whose rigidity is tuned to the central trajectory can pass throughthe triplet quadrupole magnets between DMT 2 and3, while beams with neighboring charge states are considered to be partially blocked by walls in the middleof the Q magnet.
Tests of the transport were performed as a program DA03 on 2021/11 and 2022/03. Figure 2(a)shows one of the results on a proﬁle monitor at T21
with the 250 MeV/nucleon transport. The neighboring charge state was actually observed as a separate
peak on the momentum dispersion axis (X) in the
proﬁle monitor located at T21. The magnetic rigidity was set at 92+ in the central trajectory. The results veriﬁed that the beam passing through the central orbit is 92+ of the charge state, because 91+ beam
was observed at neighboring higher momentum while
93+ was not observed. In this condition, the beam
spread was conﬁrmed by an alumina ﬂuorescent plateat F0 shown in Fig. 2(b1), which is comparable withthose observed at 345 MeV/nucleon (Fig. 2(b2)). At
150 MeV/nucleon, the condition was not as good asthat at 250 MeV/nucleon and the T21 separation was

XX.XX.XXX YY:YY:YY

U 92+
U 91+

T21

MQ

MQ

MAGNETICQUADRUPOLMAGNETIC
SECTOR

MQ

MAGNETIC
SECTOR

MQ

MQ

T11

U 90+

BigRIPS F0

X-MAX 0.100 m

a)

x

U 93+

U 92+

U 91+

252 MeV/u

Beam on F0 Target

Y-MAX 0.100 m

Fig. 1. Beam envelop from the T11 focus to BigRIPS F0. U
beams with three diﬀerent charge states are transported
in the calculation.
∗1

b1)

b2)

c.f. 345 MeV/u

Fig. 2. a) Beam proﬁle at T21 with U 250 MeV/nucleon.
b1) Beam spot at F0 and b2) that of 345 MeV/nucleon
for comparison.

RIKEN Nishina Center

2.000 m- 80 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)

not suﬃcient. The beam spread, as monitored by thealumina ﬂuorescent plate, was signiﬁcantly larger thanthose at 345 or 250 MeV/nucleon.
In conclusion, the energy degraded beam from345 MeV/nucleon at BigRIPS F0 was successfully delivered. This method proved that the energy-degradedbeam can be delivered without using the ﬁrst stageof BigRIPS, by utilizing the primary beam transportbeamline from T11. On the other hand, it should be
noted that the use of beams with diﬀerent charge states
are blocked by the beam duct along the beam line, especially at DMT2 or Q magnets between DMT2 and 3.
Therefore, the eﬀects of heat and radiation should beconsidered, not only for normal high-intensity beams
but also for suﬃciently reduced intensity beams.
Reference
1) T. Nishi et al., Nucl. Instrum. Methods Phys. Res. B
317, 290 (2013).

2- 81 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

FPC board design for TOGAXSI silicon trackers
K. Higuchi,∗1,∗2 J. Tanaka,∗1 T. Uesaka,∗1 H. Baba,∗1 and K. Miki∗3 for the ONOKORO collaboration
be bent 60◦ over a short distance between the silicondetector and the APV25s1 chip and designed a circuitthat satisﬁes these requirements.
The readout circuit is accommodated radially in six
directions between the silicon wafers with respect tothe beam axis. The power supply and output signalsof the APV25s1 chip, and the connectors for supplying
voltages to the silicon wafer are arranged on the upstream side of the beamline in the circuit, taking into
account cable insertion/extraction and routing.
In addition, holes are created in the bottom of the
APV25s1 chip to ensure heat conduction and to efﬁciently radiate the heat generated by the 300 mW
consumed by one APV25s1 chip. The heat-connection
part of the FPC board is designed to be thermally connected to the mounting frame. The frame is cooled bya water-cooling pipe introduced into the vacuum.
It was simultaneously conﬁrmed that the azimuthalangle coverage was maximized and that the requirements for the TOGAXSI silicon detectors, polar-angle
coverages of 36◦ –67◦ and 8◦ –30◦ and angular resolutions of less than 3 mrad, were fulﬁlled as listed inTable 1.

We are developing the detector array TOGAXSI1)
for realizing the ONOKORO project2) at RIKEN. In
order to accurately measure the angles of particles
emitted from cluster-knockout reactions, it is necessary to track the particles with silicon strip detectors
with good position resolutions. So far, we have performed test experiments using a prototype detector3)
and have established a detection and readout method
for light ions. As the next step, we designed an electronics board for the silicon detector array for TOGAXSI. In experiments with scarce radioactive isotope(RI) beams, it is necessary to maximize the azimuthalangle coverage of the detector array covering the cylindrical liquid hydrogen target STRASSE4) to ensure adequate yields with limited beam intensity. Here, we report the design of ﬂexible printed circuit (FPC) boardsfor detecting recoiled protons in cluster-knockout reactions. In order to maximize the azimuthal-angle coverage, six silicon detectors (HAMAMATSU S109385847, size: 51.0 mm × 78.4 mm) are arranged in ahexagonal shape as shown in Fig. 1. The distances
between the six detectors should be as short as possible. In addition, these detectors have 100-µm strips
in the polar-angle direction with respect to the beamaxis. In terms of noise, it is essential to connect the
APV25s15) chip, including a preampliﬁer circuit, tothe same circuit with short wiring (a capacitance of
5 pF or less). The input-pad spacing of the APV25s1
chip was 44 µm and was routed from a 100-µm-pitchsilicon detector with a line-strip spacing of 22 µm. The
direction of signal readout is the direction in which the
hexagonal silicon detectors are adjacent, which interferes with conventional planar printed circuit boards(PCBs). Therefore, we adopted FPC boards that canTable 1. Calculated estimates of the polar-angle acceptances, polar angle resolutions, and azimuthal-angle acceptances of silicon detectors for recoil protons and lightions.
Polar-angle accept.
Polar-angle resolu.
Azim.-angle accept.

Second layer

References

First layer

1) T. Uesaka et al., RIBF Construction Proposal, TOGAXSI: A new detector array for inverse-kinematics
cluster and nucleon knock-out reaction experiments(2021).
2) T. Uesaka et al., Grant-in-Aid for Specially Promoted
Research, Comprehensive research of cluster formationin nuclear matter (2021).
3) K. Higuchi et al., RIKEN Accel. Prog. Rep. 55, 75(2021).
4) H. N. Liu et al., arXiv:2301.09276.
5) L. Jones, APV 25-S 1 User Guide V2.2 (2001).

Fig. 1. CAD design of the silicon tracker of TOGAXSI.

∗1
∗2
∗3

Light ions8◦ –30◦≤2.0 mrad∼74.7%At the time of reporting, the FPC board mentioned
above is being manufactured, followed by wire bonding of the silicon wafer and mounting of the APV25s1
chip. We are also designing trapezoidal silicon wafers
and FPC boards for measuring light ions by cluster
knockout reactions.

Third layer

2022 | ONOKORO | K.Higuchi

Recoil protons
35.3◦ –67.5◦≤2.3 mrad∼65.8%

70

RIKEN Nishina Center
Department of Physics, Saitama University
Department of Physics, Tohoku University- 82 -

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Study of the position dependence of the large GAGG(Ce) calorimeter
R. Tsuji,∗1,∗2 J. Tanaka,∗2 T. Uesaka,∗2 J. Zenihiro,∗1 Y. Kubota,∗2 K. Higuchi,∗2,∗3 T. Sugiyama,∗3
S. Kurosawa,∗4 H. Baba,∗2 S. Takeshige,∗5 Y. Hijikata,∗1,∗2 S. Ogio,∗1 K. Yahiro,∗1 and T. Yano∗1
A telescope named TOGAXSI array has been developed for proton induced cluster knockout measurements of reactions with inverse kinematics in
ONOKORO project.1,2) It consists of silicon strip detectors and total energy calorimeters which detectknock-outed cluster and the recoil proton. The requirements of the calorimeter are high energy resolution (σ ∼ 1 MeV), durability for high countrate (≤100 kcps) and large stopping power because
the knockout clusters which has high energy up to
250 MeV/nucleon are scattered in forward angle withhigh count rate. We employed the large GAGG(Ce)scintillator (35 × 35 × 120 mm3 ) which has high energy
resolution, high stopping power, fast response and no
hygroscopic nature.
In the pervious work, avalanche photo diodes which
size are 10 × 10 mm2 are attached to GAGG(Ce) directly and the position dependence of the light output
is drastic (∼30%).3) The behavior is similar to photon
collection eﬃciency which is mainly caused by solid angle of photo sensor.4) The suppression of the position
dependence is necessary because it cause worse energy
resolution and linearity. We tested the light guide andthe photo diode (Hamamatsu, S3584-08) which has relatively large eﬀective area (28 × 28 mm2 ) to suppress
the position dependence as shown in Fig. 1.
The beam test was performed at QST HIMAC toresearch the response such as energy resolution andposition dependence in new setup with proton and α
beams at 100–230 MeV/nucleon. The energy resolution for focused proton beam at 100 MeV is about
1 MeV (σ). To measure the position dependence, theproton beam at 100 MeV was defocused and tracked
by silicon strip detector. The deﬁnition of the coordinate is shown in Fig. 1. The position dependence in yand z direction is suppressed to less than 1% with the
new setup.
Figure 2(a) shows the position dependence in x direction. The position dependence of left and right
light output is relatively small at the region far fromthe each photo diodes. On the other hands, the light
output of them decrease and increase near the eachphoto diodes. The photon collection eﬃciency explains this phenomenon. Figure 2(b) shows the result of the simulation of the photo collection eﬃciency
with Monte Carlo simulation. In this simulation, thephotons which are emitted isotropically from the des∗1
∗2
∗3
∗4
∗5

Fig. 1. The setup of GAGG(Ce) calorimeter.

(a)geometrical meanR
L

light output (a.u.)

1.04

1.02

1

0.98

0.96

L

-80

R
-60

-40

-20

(b) 30406080geometrical meanRL

28
photo efficiency (%)

020
x (mm)

26
24
22
20
18
16
-80

L

R
-60

-40

-20

0
20
x (mm)

40

60

80

Fig. 2. The position dependence of the GAGG(Ce)calorimeter. (a) The light output measured with
100 MeV proton beam. (b) The photon collection eﬃciency simulated with Monte Carlo method.

Department of Physics, Kyoto University
RIKEN Nishina Center
Department of Physics, Saitama University
NICHe, Tohoku University
Department of Physics, Rikkyo University

ignated point in the crystal are totally reﬂected at thesurface of the crystal and light guide and refracted at
the boundary of materials. The behavior of position- 83 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)

dependence near the photo diodes is similar to the experimental results but the absolute value is not duplicated. The light outputs of left and right photo diodes
matches at |x| < 30 mm in Fig. 2(a) and it supportsthat eﬀect of photon collection eﬃciency is small at
the region far from photo diodes. Another cause of
position dependence is the nonuniform composition of
the crystal such as concentration of the doped cerium.
The increase of the light output of both left and rightphoto diodes around x = −10 mm can be caused bythis eﬀect. In the new setup, the position dependence
in y and z direction is suppressed and the total position
dependence decreases under 4%. With the correction
with silicon strip detectors, the energy resolution canbe improved to under 1% for 100 MeV proton in thisdata.
References
1) T. Uesaka et al., RIBF Construction Proposal, NP2112SAMURAI72 (2021).
2) T. Uesaka et al. Grant-in-Aid for Specially Promoted
Research, “Comprehensive research of cluster formationin nuclear matter” (2021).
3) R. Tsuji et al., RIKEN Accel. Prog. Rep. 55, 76 (2021).
4) R. Tsuji et al., Master thesis, Kyoto University (2022).

2- 84 -

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Integration of VX2740B digitizer into babirl DAQ
S. Ogio,∗1 H. Baba,∗2 J. Zenihiro,∗1 R. Tsuji,∗1 and T. Yano∗1 for the ONOKORO Collaboration
We investigate cluster formation mechanism dependent on isotope and the kind of clusters by (p, pX)
cluster knock-out experiments and inverse kinematics
reconstruction with TOGAXSI array,1) which named
ONOKORO project.2) It is diﬃcult that approximately
100 ch signals from TOGAXSI array are processed ina conventional analog circuit and combined into output triggers based (p, pX) kinematics. CAEN digitizer
VX2740B is a promising candidate to obtain data fromGAGG scintillators of TOGAXSI array, process complex
logic signals, and generate triggers.
VX2740B digitizer is an 125 MS/s ADC having 64
analog inputs, compliant with VME64X standard which
has a 62.5 MHz internal clock. Pulse height is sampled
by the 16-bit ADC in full-scale range of 2 Vpp. The
VME crate is used only as a power supplier. Data is
obtained via USB-3.0, 1/10 Gigabit Ethernet, or optical link cables attached to the front panel. Digitizedsignal, which is temporarily stored in 2.5 GB memory,is processed in FPGA Xilinx Zynq UltraScale+ implemented on VX2740B board. If the data rate is too high,the memory becomes full, VX2740B outputs intrinsic
busy signals and the eﬃciency is signiﬁcantly suppressed.
CAEN provides ﬁrmware and C libraries named “FELib”
for the basic waveform processing. Here we have developed a new program to integrate VX2740B into babirl
DAQ.3) It is called as babies for VX2740B and it utilizes
FELib.
The H424 experiment4) was carried out in PH2 course
at QST, HIMAC and we conﬁrmed that VX2740B canwork properly under the experiment condition as a ﬁrst
development. Beam nuclide is 4 He, 16 O, 40 Ar and allof their energy were set to 230 MeV/nucleon. ESPRI
chamber, drift chambers and ONOKORO chamber werealigned from the beam upstream to the downstream.
The detector data except those of VX2740B were obtained by MPV5) which is a VME-based DAQ system.
24 signals from GAGG in the ONOKORO chamber and2 signals from GAGG read out with photodiodes in the
ESPRI chamber were divided and entered into VX2740B
and conventional CAEN ADC V785 installed in MPV.
In this experiment, “scope” ﬁrmware was used to acquire waveforms by VX2740B. VX2740B was driven by
a common external trigger from the babirl DAQ whiledata from VX2740B and the babirl DAQ were saved inseparate ridf ﬁles. To synchronize the timestamp information, which eanbles merging separately stored data, a62.5 MHz internal clock of VX2740B was distributed to
MPV.
As a result, we have found that VX2740B did not output busy and then VX2740B event counts are almost
the same as babirl DAQ when input channels were 26∗1∗2

Department of Physics, Kyoto University
RIKEN Nishina Centerand trigger rate was approximately 1 kHz. As shown in
Fig. 1, waveforms are correctly obtained. We analyzed
the ridf ﬁles uniﬁed with timestamps in order to compare
the ADC values of V785 obtained by existing DAQ with
the PHA values calculated from waveforms acquired by
VX2740B, resulting the linear correlation event by event(Fig. 2).

Fig. 1. Waveforms obtained by VX2470B.

Fig. 2. Pulse height correlation.

In summary, we have developed the babies for
VX2740B and succeeded in integrating it into babirl
DAQ. In the HIMAC experiment, we operated it simultaneously with conventional ADC V785 and conﬁrmedthat the data was obtained correctly. In future studies,
we plan to test the triggering function of VX2740B with
“DPP-PHA” ﬁrmware provided by CAEN.
References
1) T. Uesaka et al., RIBF Construction Proposal, NP2112SAMURAI72 (2021).
2) T. Uesaka et al., Grant-in-Aid for Specially Promoted Research (2021).
3) H. Baba et al., Nucl. Instrum. Methods Phys. Res. A 616,
65 (2010).
4) R. Tsuji et al., in this report.
5) H. Baba et al., IEEE Trans. Nucl. Sci. 68, 1841 (2021).

- 85 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Integration of DABC and babirl DAQ
S. Takeshige,∗1,∗2 H. Baba,∗2 J. Tanaka,∗2 K. Higuchi,∗2,∗3 and K. Yahiro∗2,∗4
In knockout measurements and elastic scattering measurements, such as the ONOKORO project1) and the
ESPRI project, the angle of the scattered particles must
be measured with high accuracy. These projects use
microstrip silicon detectors2) as position detectors. We
use DABC3) for data acquisition in this silicon detector. DABC is a data acquisition (DAQ) system developed by GSI and established for the DAQ system of
readout of these silicon detectors. In the two projects,
babirl DAQ,4) developed at RIKEN, is used for data acquisition, where babirl DAQ is DAQ software that canevent-build from multiple sub-DAQ systems. We havedeveloped additional software to link RUN operations of
DAQ between DABC and babirl DAQ and merge data
event-by-event to realize online analysis.
Figure 1 shows a schematic of the developed system.
In this development, we have aimed to integrate and separate DABC and babirl DAQ easily in a simple design.
The signals of silicon detectors are read out with analog
pipeline ASIC, referred to as APV25,5) and digitized by
the ADC module, referred to as ADCMs,6) composed of
an SFP transceiver module and FPGA. These data weresent to the DABC in response to triggers from backend
electronics referred to as TRB37) developed by GSI and
Technische Universität München. DABC event-builds
data from ADCM and saves it to the HLD ﬁle format.
Here, the ridf-plugin was added as a DABC extension to
enable communication with babirl DAQ. The ridf-plugin
is a program that streams data over the network. The
data event-built by DABC are sent to the relay program with two server sockets via the ridf-plugin. The
relay passes the data to babies, which process this data.
The processed data are sent to babirl DAQ, and event
data is constructed with data from other modules. In

this development, we have designed DABC and babies
as clients, and the relay connects both. This ensuresthat both interprocess communications are de-coupled,
and their conﬁguration does not aﬀect each other. For
RUN synchronization, the start-stop manager referred
to as babissm is used. When operating the babirl DAQ,
the start/stop command is sent to babies and babissmfrom babicon, which is the controller of the babirl DAQ.
In this case, we have added the start/stop commandfor DABC to the babissm. This allows both babies and
DABC to operate from babicon.
Figure 2 shows a schematic of the conversion from
HLD format to RIBF Data Format (RIDF). RIDF is thedata format used for babirl DAQ. In RIDF, the data are
identiﬁed by the segment header. The DABC event-built
the data and sends as a single buﬀer gathering multiple
event data. Therefore, developed babies decomposes thedata in HLD format, attach a dedicated segment header
to each event, and composes it as RIDF. Consequently,
the silicon detector data sent to babirl DAQ are written
to a ﬁle in RIDF along with data from other modules.

Fig. 2. Schematic of the conversion from HLD format to
RIDF.

We used the system in the H424 experiment, conducted in July 2022 and January 2023 at the HIMAC of
the QST. We successfully integrated DABC and babirl
DAQ in this experiment. In addition, HLD format data
could be converted to RIDF and merged on an eventby-event.
References

Fig. 1. Schematic of the DAQ integration system, where C
and S represent client and server socket, respectively. The
dotted box shows the developed part.
∗1
∗2
∗3
∗4

Department of Physics, Rikkyo University
RIKEN Nishina Center
Department of Physics, Saitama University
Department of Physics, Kyoto University- 86 -

1) T. Uesaka et al., RIKEN Accel. Prog. Rep. 55, 28 (2021).
2) K. Higuchi et al., RIKEN Accel. Prog. Rep. 55, 75 (2021).
3) J. Adamczewski et al., J. Phys. Conf. Ser. 119, 022002(2008).
4) H. Baba et al., Nucl. Instrum. Methods Phys. Res. A 616,
65 (2010).
5) L. Jones, APV25-S1 User Guide V2.2 (2001).
6) J. Michel, Development and Implementation of a New
Trigger and Data Acquisition System for the HADES Detector (2012).
7) Michael Bohmer et al., A Users Guide to the TRB3 andFPGA-TDC Based Platforms (2015).

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Fokker-planck analysis for particle motion in RUNBA
M. Wakasugi,∗1,∗2 R. Ogawara,∗1,∗2 Y. Maehara,∗1,∗2 and S. Yoshida∗1,∗2
Recycled-Unstable-Nuclear Beam Accumulator (RU
NBA) is under construction at E21 room to develop
beam recycling technology for research on precise nuclear reactions of rare nuclei. RUNBA requires special
equipment such as Energy Dispersion Corrector (EDC)and Angular Diﬀusion Corrector (ADC) to compensate
for the dilution of particles in 6D phase space owing
to the energy and ﬂight angle straggling generated by
the internal target. The principle of operation of the
RUNBA and the EDC and ADC performance required
for steady beam circulation in RUNBA have been presented in previous reports.1,2) We analyzed particle
motion using the Fokker-Planck equation, thereby conﬁrming the reliability of the RUNBA’s operation. In
this report, the results of the Fokker-Planck analysis
are presented along the longitudinal direction becauseof space limitations.
Invariant of the particle motion, Q, along the longitudinal direction is expressed asfactor and time of ﬂight between the target and EDC,
respectively, and λe is an energy correction parameterat EDC. The ﬁrst terms in Eq. (3) and the ﬁrst andsecond terms in Eq. (4) are the energy-straggling effects while the remaining terms are the contributions
from correction at EDC.
The time evolution of f (Q, t) for a 10-MeV/nucleon
12
C beam in a RUNBA with a 1018 -cm−2 thick internal
target has been calculated using the RUNBA lattice
structure and presented in a previous report.1) Figure 1
shows the time evolution of the single-particle probability density distribution f (Q, t) with and without
EDC correction, assuming a Gaussian-type distribution as the initial distribution. The black and red lines
in Fig. 1 show the results of the particle tracking simulation and numerical solutions of the Fokker-Planck
equation, respectively. The Fokker-Planck analysis reproduces the results of the particle simulation well,and this situation is similar for the transverse analysis. Thus the Fokker-Planck analysis is a useful tool
for studying beam dynamics in RUNBA.

1
Q = X 2 δϵ22+Y {cos(ϕs +δϕ)−cos(ϕs )+δϕ sin(ϕs )}, (1)where δϵ = δE/(M + Ek ), X = ηω/β 2 , Y =qV ηω/AT β 2 E, η a slipping factor, ω and V are therf angular frequency and amplitude, respectively, β avelocity, A a mass number, q a charge, T a revolution
period and ϕs and δϕ are synchronous phase and its
diﬀerence, respectively. Beam dynamics can be understood based on an analysis of the time evolution of theprovability density distribution f (Q, t) as a functionof the invariant Q. The time derivative of f (Q, t) isexpressed as the Fokker-Planck equation
∂f
∂2f
∂f
= −F
+D
,
∂t
∂Q
∂Q2

(2)

where F is a friction coeﬃcient and D is a diﬀusion
coeﬃcient. The details of the derivation of F and D are
not provided here, but they are expressed as follows:
F =

D =

X 2 2 X 2 K(λe ) 2 K(λe )
σ +
σe +
Q,
2T e
T
T

(3)

3X 4 4 X 2 2
X4σe +σe Q +(2K(λe ) − 1)σe4
8T
2T
4T
5X 2 K(λe ) 2
3K(λe )2 2
σe Q +
Q ,
+
(4)
2T
4T

Fig. 1. Time evolution of f (Q, t) without (left) and with(right) EDC correction at λe = 250 V/ns.

where σe is the rms energy straggling generated at target divided by the total energy M + Ek , K(λe ) =qηte Tte λe /Aβ 2 E, ηte and Tte are the partial slipping∗1∗2

References
1) M. Wakasugi et al., J. Part. Accel. Soc. Jpn. 19, 25(2022).
2) M. Wakasugi et al., RIKEN Accel. Prog. Rep. 55, 79,
80, 81 (2021).

Institute for Chemical Research, Kyoto University
RIKEN Nishina Center- 87 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Present operation status of ERIS at the SCRIT electron scattering
facility
T. Ohnishi,∗1 Y. Abe,∗1 D. Abe,∗2 R. Danjyo,∗2 A. Enokizono,∗1,∗3 T. Goke,∗2 M. Hara,∗1 Y. Honda,∗1,∗2
T. Hori,∗1 S. Ichikawa,∗1 S. Iimura,∗1,∗3 Y. Ishikura,∗2 Y. Ito,∗4 K. Kurita,∗3 C. Legris,∗2 Y. Maehara,∗4
Y. Nagano,∗5 R. Ogawara,∗1,∗4 R. Ohara,∗2 T. Suda,∗1,∗2 K. Tsukada,∗1,∗4 M. Wakasugi,∗1,∗4 M. Watanabe,∗1
H. Wauke,∗1,∗2 and S. Yoshida∗4

∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Research Center for Electron-Photon Science, Tohoku University
Department of Physics, Rikkyo University
Institute of Chemical Research, Kyoto University
Department of Physics, Yamagata University- 88 -of the FEBIAD type ion source at ERIS are reported
in Ref. 5). The overall eﬃciency, estimated as 5%, waslower than the previous result of 14%.5) This is because
no magnetic ﬁeld of the FEBIAD type ion source wasused to reduce the ion-beam emittance. With the optimized magnetic ﬁeld, the overall eﬃciency became thesame as the previous value. Finally, stable xenon ion
beams over a wide mass range, from 124 Xe to 136 Xe,
were supplied. For the supply of 124 Xe and 126 Xe, thegas supply volume was increased because the existing
supply volume was insuﬃcient owing to their low natural abundance ratio. An ion beam current, almost 1 nA,
was achieved in case of 124 Xe, while maintaining thepressure inside the ion source in the order of 10−4 Pawith careful control of the gas supply. Figure 1 shows
the mass spectrum. 124 Xe and 126 Xe were clearly separated and measured. After cooling and stacking inside
FRAC, 108 ions/pulse of each Xe isotopes, including
124, 126Xe, were transported to the SCRIT system.
0.6
128

0.5

Voltage [V]The electron-beam-driven radioactive isotope separator for SCRIT (ERIS)1) at the SCRIT electron scattering facility2) is an online isotope-separator system used
to produce low-energy radioactive isotope (RI) beams
using the photoﬁssion of uranium. The RI beam production at ERIS began in 2013 and has been vigorously
developed. This year, two full-scale ion beam operations were conducted for physics experiments. The ﬁrst
was the 137 Cs ion-beam production for electron scattering experiment with RI. The second was the ion beam
supply of Xe isotopes for the systematic study of nuclear structure using electron scattering. In this paper,
we report details of both these operations.
The 137 Cs ion-beam production was performed in thespring of 2022. 137 Cs nuclei were produced via photoﬁssion of uranium, and they were ionized and extractedwith the surface ionization technique. Details of the137
Cs beam production are reported in Ref. 3). In thisoperation, self-made 48 uranium carbide disks, withthickness and diameter of 0.8 and 18 mm, respectively,
were used as production targets and the total amountof uranium was approximately 28 g. A 150-MeV electron beam with beam power of approximately 15 W
irradiated to the production target heated to around2000◦ C using the resistive heating method. Ionized RIs
were stacked in the ionization chamber for 25 ms, extracted as a pulsed beam by the exit grid of the ionization chamber, and then accelerated to 6 keV. Following mass selection, the pulsed 137 Cs ion beam was
injected into a RFQ cooler and buncher, FRAC.4) Approximately 107 ions/pulse for 137 Cs, accumulated for
4 s inside FRAC, were transported to the SCRIT system for the electron scattering experiment. During themeasurement, which was approximately one month operation, the ERIS operation was very stable. Although
there were concerns regarding the lifetime of the production target, the amount of produced RI remained
almost constant because of the good quality of the target. It is important to establish a target-production
method that guarantees the quality.
The ion beams of Xe isotopes have been supplied
since this summver. The FEBIAD type ion source wasused for the ionization of Xe, and natural Xe gas was
injected directly into the ionization chamber. Details

Xe

0.4
0.3
0.2
0.1
0
57.5

124

Xe

58

126

Xe

58.5

59

59.5

I [A]

Fig. 1. Mass spectrum around 124 Xe and 126 Xe plotted withthe current value of the analyzing magnet.

Currently, the experiments with Xe isotopes are stillongoing. As the next research objective, further development of ERIS is planned to accommodate the upgrade of the electron beam power to a few kW. For
example, the radiation shield and the remote handlingsystem are being considered for updates.
References
1) T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B
317, 357 (2013).
2) M. Wakasugi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 668 (2013).
3) Y. Abe et al., RIKEN Accel. Prog. Rep. 55, S19 (2022).
4) M. Wakasugi et al., Rev. Sci. Instrum. 89, 095107 (2018).
5) T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B
463, 290 (2020).

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Improvement of gas inlet system for FRAC at SCRIT facility
S. Iimura,∗1,∗2 T. Ohnishi,∗2 T. Yamano,∗1 Y. Abe,∗2 K. Kurita,∗1 R. Ogawara,∗3,∗2 M. Wakasugi,∗3,∗2
M. Watanabe,∗2 and H. Wauke∗4,∗2
At the SCRIT facility,1) we have been studying thecharge density distribution of unstable nuclei using theelectron scattering method. To perform electron scattering with radioactive isotopes at a low production
rate, it is necessary to convert the ions generated continuously by the ISOL-type ion separator, the electronbeam-driven RI separator for SCRIT (ERIS),2) toa pulsed beam with an eﬃciency as high as possible. A fringing-RF-ﬁeld-activated dc-to-pulse converter (FRAC)3) is a gas-ﬁlled beam cooler buncher
developed for this purpose and achieves an accumulation of 107 ions with an eﬃciency of approximately
90%.4,5) However, a decrease was observed in the accumulation eﬃciency with a longer stacking time (seethe blue squares in Fig. 2), and there were concernsthat contaminants with small ionization potential in
the noble gas could neutralize and molecularize thetarget ions. Therefore, a buﬀer gas puriﬁcation system was introduced in the FRAC.
Figure 1 presents a schematic of the newly modiﬁed
gas inlet system. Neon gas was puriﬁed to the ppb
level or less of impurities using a ﬁlter (IG-105-200630,
ARM Puriﬁcation) and ﬂowed into the FRAC, where
the gas pressure was controlled to ∼10−3 Pa throughdiﬀerential pumping. A further improvement was theinstallation of a variable leak valve (951-7170, Canon
ANELVA) instead of the needle valves. This valve enabled microﬂow control and signiﬁcantly contributed
to optimizing the gas pressure in the FRAC. Following
assembly, all the gas lines were evacuated and baked at110◦ C for nearly a day to eliminate as much residual

 

      

0.9

∗2
∗3
∗4

without purifier  with purifier   110  100

 

1000

Fig. 2. Dependence of stacking time on FRAC eﬃciency
with (red solid circles) and without (blue solid squares)
puriﬁer.

This study has established the signiﬁcance of buﬀer
gas purity, and the possibility of longer accumulation
times and more eﬃcient cooling at higher pressures
has indicated the possibility of the electron scatteringof exotic nuclei with small production yields in the
future.

Fig. 1. Schematic of the gas inlet system before (blueframe) and after (red frame) modiﬁcation. Neon gas
was regulated at 0.11 MPa before the variable leakvalve, and the microﬂow rate was controlled and introduced downstream of the valve to the FRAC.
∗1

0.7

0.5

    

0.8

0.6



 1   

impurity as possible.
Oﬄine experiments were performed to evaluate theimproved eﬃciency. The 132 Xe+ ion beam deliveredfrom ERIS was injected into the FRAC for 0.4 ms at
1 Hz (∼107 ions/cycle), trapped and cooled (for 1–
1000 ms), and subsequently ejected into a Faraday cup
located downstream of the FRAC to measure the ion
current. The FRAC was operated with a 1.8 MHz,
1 kVpp RF ﬁeld and a DC potential of depth 30 V along
the beam axis at a neon gas pressure of 2.0 × 10−4 Pa.
Figure 2 presents the oﬄine test results of the stacking time dependence of the accumulation eﬃciency
with and without the puriﬁer. The eﬃciencies weredeﬁned as the ratio of the ion current to that without
stacking in the FRAC. Before the improvement, the efﬁciency started decreasing after 10 ms of stacking anddropped to approximately 66% at 500 ms, whereas theintroduction of gas puriﬁcation enabled the eﬃciency
to be maintained at over 90% for more than 1 s.

References
1) M. Wakasugi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 668 (2013).
2) T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B
317, 357 (2013).
3) M. Wakasugi et al., Rev. Sci. Instrum. 89, 095107(2018).
4) S. Sato et al., RIKEN Accel. Prog. Rep. 52, 144 (2019).
5) S. Sato et al., RIKEN Accel. Prog. Rep. 53, 111 (2020).

Department of Physics, Rikkyo University
RIKEN Nishina Center
Institute for Chemical Research, Kyoto University
Research Center for Electron-Photon Science, Tohoku University- 89 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Charge state distributions of 138 Ba ions trapped in the SCRIT
R. Ogawara,∗1,∗2 Y. Abe,∗1 T. Ohnishi,∗1 A. Enokizono,∗1 K. Kurita,∗3 Y. Maehara,∗1 K. Tsukada,∗1,∗2
M. Wakasugi,∗1,∗2 M. Watanabe,∗1 and H. Wauke∗1,∗4

∗1
∗2
∗3
∗4

RIKEN Nishina Center
Institute for Chemical Research, Kyoto University
Department of Physics, Rikkyo University
Research Center for Electron Photon Science, Tohoku University- 90 -

times. The incident energy of 138 Ba1+ ions to the
SCRIT device was 6 keV. The energy and current of
the electron beam were 150 MeV and 210–270 mA, respectatively. The ﬁxed magnetic ﬁeld was 1850 G, andthe range of supply voltages for electric ﬁeld scanningwere 0–2400 V in 10 V steps.
Figures 1 (a), (b), and (c) show the charge state distributions of 138 Ba ions at trapping times of 30, 100,
and 200 ms, respectatively. The 138 Ba1+ ∼ 138 Ba7+
ions were clearly identiﬁed, comﬁrming that the ionsin higher charge states can be identiﬁed compared tomeasurements for 133 Cs ions.2) The 138 Ba1+ ions were
dominant at a short trapping time of 30 ms, but the
charge state distributions of the 138 Ba ions were bredand spread with increasing the trapping time. The average charge states at trapping times of 30, 100, and
200 ms were 1.3, 2.5, and 3.6, respectatively. These results show that the developed method is useful for evaluating the charge state distributions of trapped ions in
the SCRIT.
(a) trapping time: 30 ms
500

138

Ba1+

138

Ba2+

250
Ba4+

138
138

Event rate [/gate]

The self-conﬁning radioactive isotope ion target(SCRIT) method is an internal-target-forming technique for realizing electron scattering with unstable
nuclei.1) Target ions are injected into the SCRIT device and are trapped transversely by periodic focusing forces from electron beam bunches and longitudinally by the electrostatic well potential.2) While thetarget ions are trapped in the SCRIT device, SCRIT
performance (number of trapped ions, charge distributions, etc.) continues to change. Previous studies haveshown that the instability of the electron beam is oneof the major sources of trapped ions escaping from the
SCRIT.3) The trapping lifetime of the ions with a small
mass-to-charge ratio (A/q) is shorter than that of theions with a large A/q. Therefore, to optimize SCRIT
performance, it is necessary to evaluate the charge state
distribution of the trapped ions.
After trapping ions in the SCRIT device, the target
ions are extracted and transported to an ion analyzer
consisting of a total charge monitor, an E × B velocity ﬁlter (Model 600-B, Colutron Research Corp.), anda 43-channeltron array (Photonis Scientiﬁc, Inc.).3) In
previous work,2) the charge state distributions of 133 Csions were measured by an ion analyzer with ﬁxed electric and magnetic ﬁelds in the E × B velocity ﬁlter.
The 133 Cs1+ ∼ 133 Cs3+ ions were identiﬁed clearly,
but it was diﬃcult to evaluate the abundance ratio of
the133 Cs1+ ∼ 133 Cs3+ ions because of the diﬃculty associated with correcting the detection eﬃciencies of thechanneltrons, which depended on the position and angle of incidence and the individual diﬀerences in thechanneltrons.
We developed a measurement method for the ion analyzer using a ﬁxed magnetic ﬁeld and an electric ﬁeld
scanning in the E × B velocity ﬁlter. In this method,
the same number of trapped ions are injected into allchanneltrons by electric ﬁeld scanning so the detection
eﬃciencies of all channeltrons can be measured simultaneously with measurements of the charge state distributions. The charge state distributions measured byeach channeltron are corrected for the detection eﬃciencies and added to improve the statistical accuracy. The
performance of the developed method was evaluatedby simulating 138 Ba ion trajectories using the RungeKutta method, and it was conﬁrmed that 138 Ba1+ ∼138
Ba10+ ions can be identiﬁed.
We measured charge state distributions of 138 Ba ionsusing the developed method while varing the trapping

138

Ba5+

Ba

3+

0

(b) trapping time: 100 ms
138

500
138

Ba4+

138

250

Ba

Ba2+

3+

138

Ba5+
138

Ba1+

138

Ba6+

0

(c) trapping time: 200 ms
500
Ba5+ 138 4+
Ba

138

250

138

Ba

138

0

6+

138

Ba3+

138

Ba7+

101

Ba2+

102

Mass-to-charge ratio (A/q)

Fig. 1. Charge state distributions of 138 Ba ions with trapping times of (a) 30, (b) 100, and (c) 200 ms.

References
1) K. Tsukada et al., Phys. Rev. Lett. 118, 262501 (2017).
2) M. Wakasugi et al., Nucl. Instrum. Methods Phys. Res.
B 317, 368 (2013).
3) R. Ogawara et al., Nucl. Instrum. Methods Phys. Res. B
317, 674 (2013).

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Installation of the NEBULA-Plus neutron array
N. A. Orr,∗1 J. Gibelin,∗1 Y. Kondo,∗2 and H. Otsu∗3
on behalf of the NEBULA-Plus Collaboration∗1,∗2,∗3,∗4
The direct investigation, through high-energy reactions and invariant mass spectroscopy, of neutron
unbound states and systems requires the detectionof one or more neutrons. In the case of the RIBF,
the principal permanently available fast neutron detector is the two-wall 120-element NEBULA array,1)which has been in operation since the commissioningof the SAMURAI setup in 2012. In order to augment
the detection eﬃciency, in particular for multineutron
channels, an upgrade comprising two supplementary
walls to be located just forward of NEBULA (Fig. 1)
has been built within the context of the French ANR
funded project EXPAND.2)

After detailed acceptance testing of all the bars and
PMTs at LPC-Caen and optimization of the operationof the FASTER electronics (in particular the timing
and charge measurements) NEBULA-Plus was shippedto the RIBF in summer 2022, following the easing ofcovid travel restrictions. The mechanical installationand cabling were completed in early October (Fig. 2)
and were followed by the installation of the high voltage system and electronics. Extensive testing wasthen performed during October and early November
using cosmic rays and γ-ray sources with NEBULAPlus running in a stand alone mode with FASTER.
Subsequently the eﬀort has been focused on the coupling of the FASTER electronics and DAQ with thatof SAMURAI. At the time of writing (January 2023)
this work and that required to merge the NEBULAPlus data with that from the SAMURAI detectors has
been completed and tested with cosmic ray data acquired with NEBULA and NEBULA-Plus operated intandem. Initial in-beam commissioning is planned to
be undertaken using the well-known 7 Li(p, n) reaction
which will also enable the single-neutron detection efﬁciency of NEBULA-Plus to be determined.4)

Fig. 1. Schematic view of the SAMURAI setup including
the NEBULA-Plus and NEBULA arrays.

The NEBULA-Plus walls are composed of a totalof 90 plastic scintillator bars (Eljen EJ200), with dimensions identical to those of NEBULA,1) read out
by Hamamatsu H11284 PMT assemblies. Each wallis composed of two layers - with each layer in the ﬁrst
wall comprising 22 bars and in the second wall 23 bars.
As for NEBULA, each of the walls is preceded by alayer of thin (1 cm thick) large area charged-particle
veto detectors. The read out of the PMT signals is
performed using the FASTER digital electronics andacquisition system3) developed at LPC-Caen. Whilst
FASTER has been conceived as a triggerless system,
it has been modiﬁed for use with NEBULA-Plus togenerate a trigger (derived from the coincidence between the signals from the two PMTs of each bar) so
as to allow for its integration into the SAMURAI dataacquisition system (DAQ).
∗1
∗2
∗3
∗4

Fig. 2. View of the NEBULA-Plus array, including the vetodetectors, prior to the installation of the electronics.

References
1) T. Nakamura et al., Nucl. Instrum. Methods Phys. Res.
B 376, 156 (2016).
2) EXPAND: “Explorations Beyond the Neutron Dripline,”
ANR-14-CE33-0022-02.
3) http://faster.in2p3.fr/ .
4) Y. Kondo et al., Nucl. Instrum. Methods Phys. Res. B
463, 178 (2020).

LPC-Caen, France
Department of Physics, Tokyo Institute of Technology
RIKEN Nishina Center
Department of Physics, Tokyo City University- 91 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Silicon tracker array for RIB experiments at SAMURAI†
A. I. Stefanescu,∗1,∗2,∗3 V. Panin,∗4 L. Trache,∗1 D. Tudor,∗1,∗2 I. C. Stefanescu,∗1,∗2 J. Tanaka,∗3 H. Otsu,∗3
T. Motobayashi,∗3 A. Spiridon,∗1 and T. Uesaka∗3 for HI-p Collaboration
A silicon tracker for use in front of the SAMURAI
spectrometer at the RIBF facility of the Nishina Center of RIKEN, Wako, Japan was designed, built andtested.1) The tracker consists of two pairs of singlesided microstrip detectors that determine the (x, y)
position at two locations along the beamline after thetarget. The system provides particle identiﬁcationfrom protons up to Z ∼ 50 heavy fragments with energies 100–350 MeV/nucleon. GLAST-type 325 µm
thick detectors were used. The inherent problems
stemming from the large granularity, the required verylarge dynamic range and counting rate were handledusing two matched ASICs: a dual-gain preampliﬁer
DGCSP and the HINP16 pulse processing system.
Combining the HINP16 ASICs with the newly developed dual-gain preampliﬁers, produces 2 × 4 × 128= 1024 channels. (Lo/Hi gain × 4 Si each with 128
channels.) This system yields a very large dynamic
range of ∼104 . It can work in a self-triggering mode orin slave mode where it requires an external trigger andcan tolerate very large input capacitance. The large
dynamic range, provided by the dual-channel preampliﬁer, makes it possible to measure a wide range of
nuclear charges. Parts of the system were tested withbeams from the HIMAC facility in Chiba, Japan, toshow that it can measure energy losses from 100 keV(protons) to 600–900 MeV (for heavy fragments up to
Z = 50), which makes it appropriate for the studies
with radioactive ion beams at intermediate energies.
The whole system was used and characterized in
two RIBF experiments (NP1412-SAMURAI29 andNP1406-SAMURAI24), using the SAMURAI magnetic spectrometer. The silicon detection system was
successfully used to track protons and heavy fragments
simultaneously in the breakup of the proton-rich nuclei, (like 9 C and 66 Se) to reconstruct the reaction vertex, the emerging angles of the particles, the momentum distributions of the protons and the relative energy spectra. We run the system with 1.2 × 103 Hz
132
Xe beam rate during the HIMAC test and with
4 × 104 Hz of 9 C beam, and we assume that the maximum rate can be higher. However, the damage ofthe detector may become important. The problem becomes more complex because the center of the detector
system takes a larger rate of hits and will lead to local
damages. And it is more important for heavier (sec-

ondary) beams. This will be addressed by replacing
the detectors when necessary.
To achieve the science objectives of the experimentswith proton-rich radioactive beams in which we have tomeasure the proton and the heavy ion remnant, the essential tracking performances are: the atomic number
identiﬁcation, the vertex reconstruction resolution, theangular resolution and the momentum reconstruction
resolution. All these are required to determine with agood energy resolution the missing mass spectra. We
illustrate these with the case of the proton breakupof 9 C at 160 MeV/nucleon. The physics objectives
are to disentangle the E1 and E2 contributions to the
Coulomb dissociation process on a lead target and toevaluate the astrophysical factor, S18 (0) by separating
the contribution of the resonance at 918 keV. The resolutions obtained with the silicon system are resulting
from the incoming beam phase space characteristics,
the strip pitch size (0.684 mm), the distance between
target and the ﬁrst pair of detectors and the distance
between the two pairs of detectors. With the 4 silicondetectors used in the conﬁguration presented in the article, the resolution of the longitudinal distance (σ =35 mm) is suﬃcient to separate the spurious events induced by the beam in the other materials around thetarget, as illustrated in Fig. 10(b) of Ref. 1). The angular resolution obtained for the laboratory opening
angle is 3.5 mrad and the largest contribution is coming from the proton straggling in the ﬁrst two siliconlayers (straggling in 0.650 mm Si ≈ 2.8 mrad). By using these silicon detectors for proton tracking together
with the proton drift chambers mounted at the exitof the SAMURAI superconducting magnet, we got for
proton momentum resolution: ∆P/P ≈ 0.065%. Considering these resolutions, we expect that at 1 MeV
relative energy of p-8 B we get the energy resolution of≈100 keV, about 2.5 times better than without the silicon tracker, which is suﬃcient to determine the crosssection at energies below the resonance and to evaluate
S18 (0) by extrapolation.
This silicon tracker dramatically extends the research opportunities with the SAMURAI spectrometer
especially for systems with two or more charged particles, which had been too diﬃcult with the standard
detectors equipped in SAMURAI.
Reference

†

∗1
∗2
∗3
∗4

1) A. I. Stefanescu et al., Eur. Phys. J. A 58, 223 (2022).

Condensed from the article in Eur. Phys. J. A 58, 223 (2022)
Horia Hulubei National Institute for R&D in Physics andNuclear Engineering
Doctoral School of Physics, University of Bucharest
RIKEN Nishina Center
GSI Helmholtzzentrum für Schwerionenforschung GmbH

- 92 -

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of a new conﬁguration for the liquid hydrogen target
X. Wang,∗1 M. Kurata-Nishimura,∗2 H. Wang,∗3 T. Gao,∗2,∗4 K. Horikawa,∗5 H. Otsu,∗2 and K. Takahashi∗5This study reports the development of a new conﬁguration for the liquid hydrogen target, using a cryogenic proton and alpha target system (CRYPTA).1) We
study the complete kinematics of p(10 Be, pd ) reactionsat 230 MeV/nucleon. Recoil protons and deuterons exhibits a large scattering angular range (0◦ –70◦ ). To
cover these particles, we develop a new conﬁguration
for the liquid hydrogen target system located inside theCAesium iodide array for γ-ray Transitions in Atomic
Nuclei at high isospin Asymmetry (CATANA)2) frame.
Figure 1(a) shows the conceptional image of the new
conﬁguration and (b) shows the internal structure of thevacuum chamber. A 70-cc copper (Cu) buﬀer tank isconnected to the ﬁrst stage of a Giﬀord-McMohon cycle
refrigerator (ULVAC R20) using a 45-cm long Cu pipe.
A SUS O-ring is used to avoid leakage, and a small Curing is inserted to improve heat conductivity. The target cell is made of oxygen-free Cu and connected to thebuﬀer tank by two Cu tubes, which are used for inlet(green) and outlet (magenta), respectively. Havar foilwith a thickness of 6.5 µm was glued to the Cu window of the target cell and sandwiched by a Kapton ring.
Figure 1(c) shows the size of the target cell. The thickness of the target cell is 15 mm. The deformation of theHavar foil was measured to be 2 mm with a diﬀerenceof 1.2 atm. In the new conﬁguration, the target cell islocated at the downstream side of the vacuum chambernear the exit window (Fig. 1(b)). The chamber will beinserted into the CATANA frame. As a result, the cen-ter of the target is 25 cm more downstream than thecenter of the cryogenic head along the beam direction,
thus covering a solid angle of approximately 2π.
Temperature is monitored using two silicon diodethermometers (Scientiﬁc Instruments Si410AA). The
thermometers are labeled as “Sensor A” (SA) (placed
below the heater) and “Sensor B” (SB) (placed at thebottom of the buﬀer tank) (Fig. 1(a)). Figure 2 shows
the variation in temperature and pressure with coolingtime in a cooling test. The target cell and buﬀer tank
was ﬁrstly pumped out at room temperature. It took lessthan 3 hours to cool SA from room temperature to 20 K,
whereas SB was at 25 K. Then the heater started to operate and SA was maintained at 20 K. SB was cooled
down to approximately 24 K with vacuum, and the system achieved dynamic equilibrium. Hydrogen gas was
ﬁlled into the cell at 1650 hPa and liqueﬁed near the cold
head. Liquid hydrogen ﬂew down gradually and cooled
the system down to 21 K (Fig. 2(b)). Finally, the pressure was stabled at 1111 hPa, which is 33% lower thanthe pressure at which hydrogen gas was ﬁlled, indicating that the buﬀer tank and target cell was fully ﬁlled
by liquid hydrogen. It took approximately 1.5 hours tocompletely ﬁlled the buﬀer tank and target cell. In the
new conﬁguration, it takes 4.5 hours to cool down andfully ﬁll the system with liquid hydrogen.

Fig. 2. Variation in temperature and pressure with time ina cooling test: (a) overall variation; (b) zoom-in view ofthe hatch area illustrated in (a).

In summary, we have developed a new conﬁguration for the liquid hydrogen target system based on
CRYPTA. By implanting the buﬀer tank, the target cellis placed near the center of CATANA. The system will
be used ﬁrst in the SAMURAI-53 experiment. Moreover, such a new conﬁguration can be applied to the
DALI2 array to study in-beam γ-ray spectroscopy.
Fig. 1. New conﬁguration: (a) conceptional image; (b) insideof the vacuum chamber; (c) the size of the target cell.
∗1
∗2
∗3
∗4
∗5

Research Center for Nuclear Physics, Osaka University
RIKEN Nishina Center
High Energy Nuclear Physics Laboratory, RIKEN
Department of Physics, University of Hong Kong
Department of Physics, Tokyo Institute of Technology- 93 -

References
1) H. Ryuto et al., Nucl. Instrum. Methods Phys. Res. A
555, 1 (2005).
2) Y. Togano et al., Nucl. Instrum. Methods Phys. Res. B
463, 195 (2020).
3) S. Koyama and D. Suzuki, RIKEN Acce. Prog. Rep. 52,
148 (2019).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Improvements in cooling operations of the SAMURAI magnet
H. Sato,∗1 H. Otsu,∗1 M. Kurata-Nishimura,∗1 M. Ohtake,∗1 and K. Kusaka∗1
The operational policy for the SAMURAI superconducting dipole magnet is that the magnet is cooled foreach SAMURAI campaign experiment and warmed after the experiments in order to save operating time andthus extend the cryocooler maintenance cycle. In linewith this policy, the magnet has been at room temperature since 2020. Cooling operation of the magnet
was performed from 2022/5/9 to 2022/6/2 for the upcoming experiments. Previously, we reported on theﬁrst magnet cooling conducted in 2014.1) This report
describes the improvements made to the work environment and operating procedures since then.
The procedure for cooling is as follows:





(1) evacuation of the vacuum layers of the coil vessels,(2) pre-cooling of the coils with liquid nitrogen,(3) removal of liquid nitrogen,(4) replacement of the inside of the coil vessels withgaseous helium,(5) transfer of liquid helium into the coil vessels.
This series of operations are performed in parallel,
shifting by one week for the upper and lower coils.
For (2), we have extended the liquid nitrogen inlet
to be closer to the magnet (Fig. 1). As a result, thehandling of liquid nitrogen ﬁlling was improved, theﬁlling operation was reduced from three days to twodays for a coil, and total liquid nitrogen was reduced
from 7125 L (2014) to 5700 L (2022).
For (5), a new gaseous helium recovery port was
installed near the magnet to facilitate recovery line
preparation and eﬀective collection of gaseous helium(Fig. 1(b)). We also introduced a 1000 L liquid helium
container and a long transfer tube. Previously, morethan ﬁve 250 L containers were needed to cool a coil. In
practice, two containers were used one after the other,making it laborious to reﬁll liquid helium and transport
the containers from the RIBF building to the heliumliquefaction building in the south area of the Wako
campus. After introducing the 1000 L container, it
was only necessary to transport one 1000 L and one
250 L container at a time. Furthermore, because of
the long transfer tube, liquid helium could be poured
from the containers placed on the ﬂoor (Fig. 2). In
addition, as the container only needs to be exchanged
once, the loss of liquid helium was reduced, resulting ina reduction in total liquid helium from 3145 L (2014)
to 2237 L (2022). The ﬁlling process was also reduced
for a coil from two days to one day.
One of the remaining issues to be improved would beto place the exhaust port near the magnet for gaseous∗1

Fig. 1. The tube for liquid nitrogen and the recovery port
for gaseous helium. (a) photo in 2014. There was norecovery port near the magnet. (b) photo in 2022.






Fig. 2. Liquid helium transfer to the lower coil using the1000 L container with the long transfer tube.

nitrogen generated during pre-cooling. Currently, we
use the port located in the ceiling of the elevator hall.
Reference
1) H. Sato et al., RIKEN Accel. Prog. Rep. 48, 201 (2015).

RIKEN Nishina Center- 94 -

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

The extraction test aiming for the laser spectroscopy of actinoid
elements by PALIS
T. Sonoda,∗1 V. Sonnenschein,∗2 H. Iimura,∗3 H. Miura,∗2 Y. Hirayama,∗4 D. Hou,∗4 S. Iimura,∗1 H. Ishiyama,∗1
I. Katayama,∗1 T. M. Kojima,∗1 S. Nishimura,∗1 M. Rosenbusch,∗3 A. Takamine,∗1 H. Tomita,∗2 M. Wada,∗4
Y. X. Watanabe,∗4 W. Xian,∗4 J. M. Yap,∗4,∗5 and BigRIPS Collaborators∗1
The laser spectroscopy of actinide RIs oﬀers an opportunity to study atomic/nuclear structure in termsof relativistic eﬀects, nuclear shell eﬀects, deformations
etc. The BigRIPS provides a wide variety of actinide
RI-beams by using in-ﬂight projectile fragmentation of
uranium. In this year, we were granted 24 hours beamtime for the extraction test of actinide isotopes and simultaneously performing a commissioning test for the
low-energy RI-beam production system by laser ionization(PALIS),1) in a director’s beam times.
During the beam time, the BigRIPS optics weretaken over from the previous beam user’s setup. The
main beam optics was 225 Ac (T1/2 = 10 d), which wasexpedient for the extraction test of actinides. Howeveras the half-life of 225 Ac was too long to measure for our
experimental setup, we fully opened the F1 slits at BigRIPS to obtain more yield of the relatively short-lived223
Ac (T1/2 = 2.1 min). Figure 1 shows the expected
RI-beams and its intensity which were implanted to the
PALIS gas cell, simulated by LISE.

219Pa 220Pa(53ns)
216Th(0.78us)217Th 218Th 219Th

222U

223U

224U

225U

226U

227U

228U

229U

230U

(1.0us)(18us)(0.7ms)(61ms)(0.35s)(1.1m)(9.1m)(58m)(4.2d)

221Pa

222Pa

223Pa

224Pa

225Pa

(5.9us) (2.9ms)(5.1ms) (790ms) (1.7s)

220Th 221Th 222Th 223Th 224Th(26.0ms) (251us) (117ns) (1.05us) (9.7us) (1.73ms) (2.24ms) (600ms) (1.05s)
214Ac

215Ac 216
Ac

(8.2s)(0.17s)(440us) (69ns)

213Ra 214Ra 215Ra(2.74m) (2.46s)
211Fr

212Fr

213Fr

(3.10m) (20.0m) (34.6s)

217Ac 218Ac

221Ac(1.08us) (11.8us) (26.4ms) (52ms)

216Ra 217Ra 218Ra 219Ra(1.55ms) (182ns)(1.6us) (25.2us) (10ms)

214Fr 215Fr

216Fr(86ns)(700ns)(5.0ms)219Ac 220Ac

217Fr(19us)

209At

210At

211At

(1.63h)(5.41h)(8.1h)(7.2h)

207Po

208Po

209Po

210Po 211Po 212Po(5.80h) (2.898y) (102y)(138d) (516ms) (294.7ns)

212At 213At 214
At 215At(314ms) (125ns) (588ns) (100us)(1.8m)(38.3m)(22h)(8.75m) (30.57m) (18.7d)

222Ac 223Ac 224Ac

225Ac 226Ac(5.0s)(10.0d) (1.224d)(2.1m)

229Pa 230Pa

231Pa

232Pa

(1.50d) (17.4d) (3.3x104y) (1.32d)

225Th 226Th 227Th 228Th 229Th(2.78h)(1.9y)(7920y)220Ra 221Ra 222Ra 223Ra 224Ra(18ms)

(28s)

(38s)

218Fr 219Fr 220Fr 221Fr(1.0ms) (20ms) (27.4s) (4.77m)

209Rn 210Rn 211Rn 212Rn 213
Rn 214Rn 215Rn 216Rn 217Rn 218Rn(28.5m) (2.4h) (14.6h) (23.9m) (25.0ms) (0.27us) (2.3us) (45us) (540us) (35ms)
208At

226Pa 227Pa 228Pa

231U 232U 233U 234U
(68.9y) (2.4x105y) (1.6x105y)(2.4x105y)

Laser
Gas cellQuadruPole Ion Guide

SextuPole Ion Guide
Alpha counting

~70cm

Exit

Differential pumping
Silicon detector

Ar 300mbar
Rotational degrader

Fig. 2. PALIS experimental setup.

Figure 3 shows the energy spectra of detected alpha particles, taken with a primary beam intensity of
10 particle nA and implantation/measurement periodof 300 s each. The rate enhancement of the alpha counting by laser eﬀect was not clearly conﬁrmed, implyingthat the extracted alpha emitters were ions that survived against neutralization inside the gas cell. The insensitivity of the laser eﬀect is attributed to the impossibility of identifying only 223 Ac from the superimposed
α-ray’s spectra by many types of α emitters, which hindered the optimization of the proper degrader thicknessfor 223 Ac. In addition, the evaluation of laser eﬀect was
distorted by other alpha-rays. Next we will utilize aprecise mass identiﬁcation device for extracted RIs.

(11.43d) (3.66d)

main beam

Alpha counts
70

alpha decay>105cps

60>10000cps>1000cps

50>100cps>10cps40

Fig. 1. Expected RI-beams and its beam intensity (primarybeam 1 particle nA, fully opened F1 slits) by LISE.

Implantation time 300s
Measurement time 300s

30

20

To conﬁrm the low-energy RI-beam extraction, the αrays produced via α decays were detected at the silicondetector, which was placed in the diﬀerential pumping
area at the PALIS, as shown in Fig. 2. The stopped
and extracted RIs from the gas cell were transported
through the sextupole and quadrupole ion beam guides,
respectively, and then deposited to the surface of thesilicon detector. To reduce the background, the beam
was stopped during α-ray measurement.
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Faculty of Engineering, Nagoya University, Nagoya
Japan Atomic Energy Agency
Wako Nuclear Science Center (WNSC), IPNS, KEK
Department of Physics, University of Hong Kong

10

0

0

200

400

600

800

1000

1200

ADC channel (the silicon detector) (ch)Fig. 3. Observed alpha spectra at silicon detector.

We successfully observed the extracted RIs as a lowenergy RI-beam. The eﬃciency improvement and theinstallation of the mass identiﬁcation are in progress.
Reference
1) T. Sonoda et al., Prog. Theor. Exp. Phys. 113, D02(2019).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Charge population investigation for the 248 Cm ﬁssion products
extracted from a helium gas catcher
A. Takamine,∗1 M. Rosenbusch,∗2 J. M. Yap,∗1,∗3 H. Ishiyama,∗1 M. Wada,∗2 S. Chen,∗3,∗4 T. Gao,∗1,∗3
D. Hou,∗5,∗6 S. Iimura,∗1,∗7 S. Kimura,∗1 T. M. Kojima,∗1 S. Nishimura,∗1 T. Niwase,∗3 P. Schury,∗2 T. Sonoda,∗1
H. Ueno,∗1 P. Vi,∗1 Y. X. Watanabe,∗2 and W. Xian∗3

∗1
∗2
∗3
∗4
∗5

∗6
∗7

RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), IPNS, KEK
Department of Physics, University of Hong Kong
Faculty of Science, University of York
Institute of Modern Physics, Chinese Academy of Sciences
School of Nuclear Science and Technology, Lanzhou University
Department of Physics, College of Science, Rikkyo University

Ti degrader (2 μm)

Outer vessel (vacuum)

Cryogenic gas cell (RTE 200 mbar He)

248

Cm source

gate valve

Ti window (50 μm)

Mylar window (6 μm)

35
30

1
0.8

He 1st IP 24.6 eV

25
20

0.6

15
10

0.2

5
0

0

10
0Y
10
0Z
r
10
3Z
r
10
0N
b
10
3N
b
10
4N
b
10
3M
o
10
4M
o
10
4T
c

0.4

Ionization potential [eV]Fig. 1. Schematic of the gas catcher cell of the ZD-MRTOF(top view). The ions are transported upwards, out ofthe page. The ﬁssion source holder attached with the Ti
degrader is movable and rotatable.

Fraction of charge population

We are developing a helium gas catcher using the RF
ion guide technique and a multi-reﬂection time-of-ﬂight
mass spectrograph downstream of the ZeroDegree spectrometer, referred to as ZD MRTOF-MS.1) We aim toconvert BigRIPS beams to ultra low energy beams andprecisely measure the atomic masses of unstable nuclei.
After highly charged radioactive ion beams enter thegas cell, their energy deposition results in the ionization of helium atoms and even impurities, and they
undergo charge exchange with the helium and impurities. The charge state that will be dominant depends
on the ionization potentials of the elements, as discussed
in Ref. 2). Although it is naively expected that charge
exchange with helium would stop when the ionization potential falls below the ﬁrst ionization potential of helium,
the mechanism for determining the charge population iscomplex because it also depends on the level of impurities in the helium gas. For eﬃcient online experiments, apriori knowledge of the element dependent charge population is essential. Recently, a 248 Cm ﬁssion source witha 2-µm-thick Ti degrader was installed outside the cryogenic gas cell (Fig. 1). The 248 Cm source has an activityof 10 kBq with branching ratios of 91.6% and 8.4% foralpha and spontaneous ﬁssion decays, respectively. The
emitted alpha particles and the spontaneous ﬁssion products enter the gas cell through a 6-µm-thick Mylar window. This setup facilitates tests with a consistent andknowable intensity of ions under a fair approximation of
online conditions.
We performed the charge population measurements for100
Y, 100, 103 Zr, 100, 103, 104 Nb, 103, 104 Mo, and 104 Tc ionsproduced by spontaneous ﬁssion decay from the 248 Cm
source oﬄine. The cryogenic gas cell temperature wasapproximately 80 K, and the gas density was equivalent to 200 mbar at room temperature (293.15 K). Theircount rates for the singly, doubly, and triply charged
states were measured with the MRTOF mass spectrograph detector. Their fractional charge population isshown in Fig. 2 with their second and third ionization potentials. It is reasonable that the doubly charged states
were predominantly extracted from the helium gas. The
fraction of triply charged ions decreases consistently with
the increase in the third ionization potential. In contrast, Zr and Y exhibited smaller triple charge fractions

1+

2+

3+

3rd IP

2nd IP

Fig. 2. Charge population of 100 Y, 100, 103 Zr, 100, 103, 104 Nb,
103, 104
Mo, and 104 Tc extracted from a helium gas cell.
The 2nd and 3rd ionization potentials for Y, Zr, Nb, andMo are plotted. The red line shows the ﬁrst ionizaton
potential of helium.

than that of Nb despite the third ionization potentials
of Y and Zr being less than Nb. This result could imply a signiﬁcant molecularization probability leading to
the loss of atomic Zr and Y ions. The charge populations are expected to depend signiﬁcantly on the gas cellconditions such as temperature, cleanliness, etc. Further
investigations with various conditions and elements andthe searching for the molecularized ﬁssion products arein progress.

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RIKEN Accel. Prog. Rep. 56 (2023)

References
1) M. Rosenbusch et al., Nucl. Instrum. Methods Phys. Res.
A 1047, 167824 (2023).
2) P. Schury et al., Nucl. Instrum. Methods Phys. Res. B
407, 160 (2017).

- 97 -

2

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Oﬄine measurement of 248 Cm ﬁssion products at ZD-MRTOF
J. M. Yap,∗1,∗2 A. Takamine,∗2 M. Rosenbusch,∗3 S. Chen,∗1,∗4 T. Gao,∗1,∗2 D. Hou,∗5,∗6 S. Iimura,∗2,∗7
H. Ishiyama,∗2 S. Kimura,∗2 T. M. Kojima,∗2 J. Lee,∗1 S. Nishimura,∗2 T. Niwase,∗3 P. Schury,∗3 T. Sonoda,∗2
P. Vi,∗2 M. Wada,∗3 Y. X. Watanabe,∗3 and W. Xian∗1
A 10-kBq 248 Cm (SF: 8.39%) ﬁssion source was installed in the gas catcher1) downstream from the ZeroDegree spectrometer to study the ion transport fromthe gas cell to the ZeroDegree Multi-reﬂection Time-ofﬂight Mass Spectrograph (ZD-MRTOF)2) in oﬄine tests,
providing pseudo conditions similar to online beam experiments. The ﬁssion source is placed between the inner gas cell and outer vessel chambers such that it canbe removed for beam-time experiments. A 2-µm Ti degrader is attached to the source to reduce the kinetic
energy of ﬁssion products and match the stopping powerof the gas cell. The degrader can also be rotated toincrease eﬀective thickness. The transport test of the
ﬁssion products, 104–106 Nb, Mo, Tc, and Ru, was performed shortly after installation. The stopped ﬁssion
products were extracted mostly as doubly charged ions,and high-precision mass measurements were made after
transportation to ZD-MRTOF. This measurement also
serves as an ion counter for transport eﬃciency measurements from the gas cell to ZD-MRTOF.
A degrader thickness scan was performed by measuring the doubly charged ion count rate at various degrader
angles to search for the condition of maximum stopping
eﬃciency. Figure 1 depicts the ion count rate of nine ﬁssion products. A similar peak count rate was determinedat the approximate angles of 45° and −60°. This diﬀerence in the positive and negative peak angular positions
is likely caused by the asymmetric structure of the gas
cell, such as the DC gradient ﬁeld applied to collect ionsat the RF carpet located on one side of the gas cell.
The maximum count rate of ﬁssion products was foundat a degrader rotation of approximately 45°, with an effective thickness of 2.83 µm. The stopping eﬃciency of
the gas cell in this condition was 4.9%, roughly estimatedby simulation, considering the solid angle, energy, energy
spread,3) energy losses, and range in the material of the
ﬁssion products. Table 1 lists the observed count rates
and transport eﬃciencies of doubly charged ions. The
transport eﬃciency is obtained after correcting for the
stopping eﬃciency from the total eﬃciency based on theﬁssion yields of 248 Cm provided by JAEA4) and the observed count rate. In the mass region of A = 104 − 106,
the Mo and Tc isotopes have a transport eﬃciency of approximately 12%, whereas the Nb isotopes have a relatively low eﬃciency of approximately 5%. The low trans-

Fig. 1. Count rate (cph) of 104–106 Nb, Mo, and Tc within the
degrader angles of −70° to 70°. The positive angles denotecounter-clockwise rotation, towards the RF carpet.

Table 1. Observed count rate (cph) and transport eﬃciencyof doubly charged 104–106 Nb, Mo, and Tc ions at a degrader angle of 45°. The uncertainty is speciﬁed in parentheses.
Isotope
104
Nb
105
Nb
106
Nb
104
Mo
105
Mo
106
Mo
104
Tc
105
Tc
106
Tc

Count rate (cph)214 (3)139 (3)38 (1)
550 (5)658 (6)712 (6)34 (1)
155 (3)296 (4)

Transport eﬀ. (%)
4.7 (24)
5.3 (17)4.0 (25)
14.0 (45)11.7 (37)13.5 (43)11.1 (71)13.5 (87)10.6 (34)port eﬃciency of the Nb isotopes could be attributed tothe diﬀerent charge distribution from the slightly lower
second ionization potential.5) Another possible factor ismolecular formation of Nb isotopes with contaminantmolecules. Further investigations on Nb isotopes will
be carried out. The oﬄine transport eﬃciency measurement forms a baseline for future improvements. Twosuch upgrade plans, the addition of an RF-wire curtain
and modiﬁcation of the RF carpet scheme from the RF+ 4-phase AF to 4-phase RF, will be tested with theﬁssion source.
References

∗1
∗2
∗3
∗4
∗5
∗6

∗7

Department of Physics, University of Hong Kong
RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), IPNS, KEK
School of Physics, Engineering and Technology, University ofYork
Institute of Modern Physics, Chinese Academy of Sciences
School of Nuclear Science and Technology, Lanzhou University
Department of Physics, College of Science, Rikkyo University

1) A. Takamine et al., RIKEN Accel. Prog. Rep. 53, 108(2019).
2) M. Rosenbusch et al., Nucl. Instrum. Methods Phys. Res.
A 1047, 167824 (2023).
3) A. Benoufella et al., Nucl. Phys. A 565, 563 (1993).
4) J. Katakura et al., EPJ Web Conf. 111, 08004 (2016).
5) A. Takamine et al., in this progress report.

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Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of a high-speed digital data acquisition system for the
ZD-MRTOF and β-decay experiments at F11
V. H. Phong,∗1,∗2 S. Nishimura,∗1 M. Rosenbusch,∗3 A. Takamine,∗3 M. Wada,∗3 H. Ishiyama,∗1 P. Schury,∗3
and J. M. Yap∗4 for the ZD-MRTOF Collaboration
A new project ZD-MRTOF has been launched tosurvey the masses of exotic nuclei using high-intensity
radioactive isotope beams at RIBF.1) Optimizing thedegrader thickness online is essential to maximize thestopping eﬃciency of rare isotopes in the He gas cell
during the experiment.2) Here, we report the performance of the newly introduced data acquisition systemdesigned for the ZD-MRTOF experiments using highspeed digitizers during the Spring campaign of the ZDMRTOF in 2022, where identiﬁcation of rare isotopes
under the beam rate of about 104 cps has been conﬁrmed with minimum event loss. The system is basedon the CAEN VME digitizers equipped with Field Programmable Gate Arrays (FPGAs), where signals thatexceed programmable thresholds are digitized and processed to extract amplitude and timing information.3)
The recorded signals are time-stamped and synchronized with the existing DAQ systems at RIBF thanks
to the use of LUPO modules,4) which distribute common 50 MHz clock signals to all digitizers.
Data acquisition is carried out using RCDAQ software.5) To combine online data from diﬀerent DDAQ
subsystems for Zerodegree, ZD-MRTOF and β-decay
setups, the ZeroMQ protocol6) was implemented. The
acquired data are distributed to data analysis computers on the network, where event reconstruction andtime correlations are performed online or oﬄine.
The performance of the DDAQ system under highrate conditions was tested using a cocktail beam ofneutron-rich Fe-Ge isotopes during the ZD-MRTOF
experiment NP2012-RIBF202. Signals from ZeroDegree spectrometer beamline detectors were readout using the CAEN V1730 digitizers running the DPP-PSD
and DPP-PHA ﬁrmwares. Figure 1 demonstrates the
improvement in deadtime using our DDAQ comparedto the existing CAMAC DAQ system, where deadtime
and event rate are evaluated based on a ﬁt of the distribution of time intervals between subsequent events toa non-extended deadtime model.7) A particle identiﬁcation (PID) plot obtained using our DDAQ system isalso shown. With the extracted event rate of 13.5 kHz,a dead time of ≈4 µs was obtained for our DDAQ system, compared to ≈377 µs for the CAMAC DAQ.
Our DDAQ system has also been successfully employed to readout the TOF signals of the ZD-MRTOF
system, providing possibility to combine with the Ze∗1
∗2
∗3
∗4

Fig. 1. Fitted distribution of the time interval between subsequent events (blue-ﬁlled) and a PID plot (inset) obtained with our DDAQ system compared to the distribution obtained with the BigRIPS CAMAC DAQ(gray-ﬁlled).

roDegree spectrometer PID information to monitor online the absolute eﬃciency of the ZD-MRTOF setup.
Figure 2 shows a TOF spectrum obtained with a 248 Cm
ﬁssion source,8) where the start signals of the mirror
ejection and the stop signals of the fast ion impact detector (ETP 14DM572)1) were recorded using a CAEN
V1730 digitizer running the DPP-PSD ﬁrmware.

Fig. 2. TOF spectrum obtained with our DDAQ system.

References
1) M. Rosenbusch et al., Nucl. Instrum. Methods Phys.
Res. A 1047, 167824 (2023).
2) S. Chen, RIKEN Accel. Prog. Rep. 54, 97 (2021).
3) https://www.caen.it/subfamilies/dpp/ .
4) H. Baba et al., Nucl. Instrum. Methods Phys. Res. A
777, 75 (2015).
5) M. L. Purschke, 2012 18th IEEE-NPSS Real Time Conference (IEEE, 2012).
6) ZeroMQ, https://zeromq.org/ .
7) J. W. Müller, Nucl. Instrum. Methods Phys. Res. A
301, 543 (1991).
8) J. M. Yap et al., in this report.

RIKEN Nishina Center
University of Science, Vietnam National University, Hanoi
Wako Nuclear Science Center (WNSC), IPNS, KEK
Department of Physics, University of Hong Kong

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

The new MRTOF mass spectrograph following the ZeroDegree
spectrometer at RIKEN’s RIBF facility†

The newly assembled multi-reﬂection time-of-ﬂight
mass spectrograph (MRTOF-MS) at RIKEN’s RIBF
facility has been ﬁnalized and became fully operational
after its ﬁrst online operation in the spring of 2020.
Further modiﬁcations and performance tests using stable ions were completed in early 2021. This system
was coupled with a cryogenic helium-ﬁlled gas cell1)
located behind the ZeroDegree (ZD) spectrometer toslow down the high-energy reaction products from initially relativistic energies to thermal equilibrium withthe helium gas, and perform high-precision mass measurements of radioactive ions at low kinetic energies.
The setup underwent a successful commissioning2)
leading to ﬁrst important mass results recently published.3) Follow-up mass measurements were performed in dedicated beam times using the SRC accelerator4) (NP2012-RIBF 199/202).
A new optimization procedure for electrostatic mirror voltages has been implemented, which uses thepulsed-drift-tube technique to modify the ions’ energy
in a wide range and optimize the isochronicity of thesystem. The TOF could be made insensitive to thekinetic energy of the ions in a wide range. This procedure provided valuable initial settings of the mirror
voltages, which have been used for further ﬁne tuning.
Figure 1 shows drift corrected TOF spectra obtained
after the full optimization, which show a mass resolving power of Rm ≈ 1 000 000. This result was reached
for a total time-of-ﬂight of only 12.5 ms for A ∼ 40,
which denotes a world record for such mass spectrometers. The new capabilities may allow for the study ofshort-lived nuclei possessing low-lying isomers.

normalized ion countM. Rosenbusch,∗1 M. Wada,∗1 S. Chen,∗2,∗3 A. Takamine,∗4 S. Iimura,∗1,∗4,∗5,∗6 D. S. Hou,∗7,∗8 W. Xian,∗2
S. Yan,∗9 P. Schury,∗1 Y. Hirayama,∗1 Y. Ito,∗10 H. Ishiyama,∗4 S. Kimura,∗4 T. M. Kojima,∗4 J. Lee,∗2
J. Liu,∗2,∗7 S. Michimasa,∗11 H. Miyatake,∗1 J. Y. Moon,∗12 M. Mukai,∗4 S. Naimi,∗4 S. Nishimura,∗4
T. Niwase,∗1 T. Sonoda,∗4 Y. X. Watanabe,∗1 and H. Wollnik∗14
1
0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0

36 Ar+

1
0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0

40 Ar+

1
0.8
0.6
0.4
0.2
0
1
0.8
0.6
0.4
0.2
0

84 Kr+a)center T OF: 11954879 ns
9204 events

4.98(19) ns

39 K+

center T OF: 12442853 ns
71914 events

6.20(20) ns

b)

center T OF: 12601321 ns
73919 events

6.20(25) ns

39 K+

center T OF: 12442868 ns
67310 events

5.99(25) ns

c)center T OF: 18260868 ns
1227 events

9.79(42) ns

85 Rb+

center T OF: 18369387 ns
107885 events
−15

−10

10.84(29) ns−50
T OF − center T OF [ns]510Fig. 1. Pairs of TOF spectra for one hour measurement
time (Ar/Kr from gas cell K/Rb and from a thermal
ion source). Numbers below double arrows: FWHM of
the TOF signals.

Furthermore, a ﬁrst accuracy benchmark of the
setup was performed using isobaric species including
stable molecules and well-known radioactive ions fromBigRIPS. The mass deviations are shown with uncer-

20

†

5
0

−5
−10
82 83 84 84 84 84 84 85 86 86 86 87 88 88 88 89 90 90 91 91

−15

r

+
l2
1H
12 C +
e 1 Hl77 S 2 C +1le 1H
78 S 12 C +l2
e 1H
77 S 12 C +le 1H76 S 2 C
1+e +l
76 S 16 O 4 37 C
2 5 Cl
12 C 3 4 +1 H F2
19
2
12 C
+
H
1
4 7 Cl 2
12 C 3
1 H +l 2 +l5C
12 C 3 4 37 C
1 H
l
5C
12 C 3+1H
l+ 2 37 Cl
13 C
37 C l
+5C+
12 C 3Cl
1 H 32 S 35
9F
12 C 1 H 4 1
4 16 O
12 C 2 +l2
1H
35 C +12 C
1 H 7 Cl
3
13 C
l
35 C
+
12 C 1 Hr +83 K 1 H- 100 -

10

82 K
+
e
82 S

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. A 1047, 167824 (2023)∗1 Wako Nuclear Science Center (WNSC), IPNS, KEK∗2 Department of Physics, University of Hong Kong
∗3 School of Physics, University of York
∗4 RIKEN Nishina Center∗5 Department of Physics, Rikkyo University∗6 Department of Physics, Osaka University∗7 Institute of Modern Physics, Chinese Academy of Sciences∗8 School of Nuclear Science and Technology, Lanzhou University∗9 Institute of Mass Spectrometry and Atmospheric Environment, Jinan University∗10 Advanced Science Research Center, Japan Atomic Energy
Agency∗11 Center for Nuclear Study, University of Tokyo∗12 Institute for Basic Science∗13 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗14 New Mexico State University

MEExp. − MEAME2020 [keV]

15

Fig. 2. Benchmark of the mass accuracy using well-known
species between A = 82 and A = 91.

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)

tainties in Fig. 2. The precisely known masses of theanalyte ions could be reproduced with an overall mean
deviation of δm/m = 2.8(99) × 10−8 , which is a value
competitive with Penning-trap systems.
References
1) A. Takamine et al., RIKEN Accel. Prog. Rep. 52, 139(2019).
2) M. Rosenbusch et al., RIKEN Accel. Prog. Rep. 54, S28(2021).
3) S. Iimura et al., Phys. Rev. Lett. 130, 012501 (2023).
4) M. Rosenbusch et al., RIKEN Accel. Prog. Rep. 55, 86(2022).

2- 101 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Improvements in the performance of the KISS MRTOF
P. Schury,∗1 T. Niwase,∗1,∗2,∗3 M. Wada,∗1 Y. Hirayama,∗1 H. Miyatake,∗1 M. Mukai,∗2 M. Rosenbusch,∗1 andY. X. Watanabe∗1
The KISS facility uses mutinucleon transfer reactions to produce nuclides which are diﬃcult to produce
by fusion or by in-ﬂight ﬁssion and fragmentation reactions. Many of these nuclides are close to stability, andtypically the more stable isobars are produced with orders of magnitude greater rates. This has made it difﬁcult to access some desirable nuclides, such as 188 W,
198, 199
Ir, and 238, 239 Pa, as resolving such nuclides fromthe next stabler isobar requires a high mass resolving
power not only in terms of full-width at half-maximum
but in terms of full-width at 1%—i.e. minimal tails.
Until recently, the MRTOF at KISS has achieved amaximum mass resolving power of ∆m/m ∼ 200,000
and the peak shape had a strong asymmetry, with therelative amplitude at ∆m ≈ +20 ppm being ≈1% of
maximum. This was not suﬃcient to the task of resolving interesting nuclides nearer stability. However,in the past year the performance of the MRTOF installed at the KISS facility has improved. The mass
resolving power has increased to ∆m/m ∼ 400,000
while the peak shape has been made signiﬁcantly more
Gaussian. The improvement is shown in the top panelof Fig. 1. The lower panel of Fig. 1 demonstrates how
the new peak shape will allow for discernment of 199 Ir
which was previously not possible.
By carefully adjusting the biasing of the MRTOF optical elements, it was possible to both improve the peak
shape and the resolving power. This eﬀort was madereasonable by the use of purpose-built high-voltage
power supplies1) which achieve a high-stability without requiring long time-constant capacitive ﬁltering.
As these power supplies settle in under one minute,it was possible to eﬃciently perform multi-parameter
optimizations. With further tuning we anticipate that∆m/m > 500,000 with a Gaussian proﬁle can beachieved, which will greatly improve our ability to resolve isobars near stability
In future experiments, we plan to use the MRTOF
as a very high-resolution isobar puriﬁer to deliver isobarically (and possibly isomerically) pure beam of radioactive ions for e.g. decay studies. This will require a high stability in the peak position. We havefound that the power supplies contribute a temperature dependent drift of ∆m/∆T = 2.36(4) ppm/K
while thermal expansion of the MRTOF itself resultsin ∆m/∆T = 20.4(6) ppm/K. In the past we observed
very large shifts in the MRTOF peak position as theroom warmed due to the presence of numerous experimenters during online measurements. To try to re∗1
∗2
∗3

Wako Nuclear Science Center (WNSC), IPNS, KEK
RIKEN Nishina Center
Department of Physics, Kyushu University

Fig. 1. (top) Comparison of MRTOF peak shape from 2021
with the improved peak shape achieved in 2022. (bottom) Simulated spectrum for A = 199 isobars based on
measured MRTOF peak shape and calculated production yields. Prior to improving the peak shape it wasvery diﬃcult to observe 199 Ir ions as they produced onlya small ﬂuctuation in the tail of the 199 Pt ion peak.

duce this eﬀect, we gently heated the MRTOF chamber using a PID regulated baking system. The resultis shown in Fig. 2. In the future we will try improving
the thermal regulation.

Fig. 2. Drift of the peak position over 16 days of measurement while roughly regulating the MRTOF chamber at
38◦ C. The maximum ﬂuctuation is consistent with athermal ﬂuctuation of ∆Tpk−pk ≈ 0.75 K.

Reference
1) P. Schury, et al., Rev. Sci. Instrum. 91, 014702 (2020).

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Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of cryogenic helium gas cell at KISS
Y. Hirayama,∗1 M. Mukai,∗2 P. Schury,∗1 Y. X. Watanabe,∗1 S. Iimura,∗2 H. Ishiyama,∗2 S. C. Jeong,∗1
H. Miyatake,∗1 T. Niwase,∗1 M. Rosenbusch,∗1 A. Takamine,∗2 A. Taniguchi,∗3 and M. Wada∗1

∗1
∗2
∗3

Wako Nuclear Science Center (WNSC), IPNS, KEK
RIKEN Nishina center
Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS)- 103 -

Straight-type
RF carpet
RF wirecarpet+Ion
source

+

+
+

+

Exit

+

MNT products
Thin window for
implanting the
MNT products
13

6

Xe

bea

m

198

Pt rotating target

Fig. 1. Cross-sectional view of the helium gas cell. MNTproducts (blue lines) are implanted into the gas cellthrough a thin window. The ﬂow of ions toward thegas cell exit by DC ﬁeld and RFTW is shown by yellow
and white arrows, respectively.

Pt counts (cps)

400

198

We have developed a cryogenic helium gas cell toeﬃciently extract unstable nuclei produced by multinucleon transfer (MNT) reactions of 136 Xe beam impinging a 198 Pt target at the KEK Isotope Separation
System (KISS).1) Unstable nuclei implanted in sucha helium (ionization potential (IP): 24.6 eV) gas cell
can survive as singly or doubly charged ions dependingon their ionization potential. In contrast to the laser
ionization used with the present argon (IP: 15.8 eV)ﬁlled KISS gas cell, a helium gas cell oﬀers faster, more
eﬃcient, and element-independent extraction of ions.
Delivering such wide isobaric cocktail beams to the existing multi-reﬂection time-of-ﬂight mass spectrograph(MRTOF-MS) will allow for high-eﬃcacy mass measurements as the device can simultaneously analyze numerous ion species. For example, in decay studies, the
MRTOF-MS could be used to provide an isobarically(or even isomerically) pure sample. Therefore, the useof a helium gas cell could provide at least one order ofmagnitude improvement in experimental eﬃcacy overthe existing argon gas cell.
Interactions of target-like and projectile-like MNTproducts and scattered primary beams, with the helium gas result in a strong plasma of He2+ and e − . Toeﬃciently transport the desired radioactive ions in sucha plasma, we manufactured a radio-frequency (RF)wire-carpet unit for use with a 4-phase RF travelingwave (RFTW) technique.2) The RF wire carpet unit
consists of 224 beryllium-copper wires (100 µm in diameter) with 600 µm pitch arranged in a plane. A
negative DC bias applied to the wire carpet accumulates ions near the wires, while a superposed 4-phase
RFTW moves the ions across the structure. Figure 1
shows a cross-sectional view of the helium gas cell installed at KISS. In the helium gas cell, a system of two
RF wire carpet units accumulates and transports ionsto a RF carpet on a Kapton substrate from which theions are extracted from the gas cell. The gas cell wascooled to T ≈ 70 K to freeze out unwanted impurities
by combining a cryo-cooler and liquid nitrogen.
We performed initial oﬄine tests to optimize the DC
and RF conditions using stable 85 Rb+ emitted from analkali ion source installed in the gas cell. The performance was then conﬁrmed in online tests by extracting the MNT products implanted in the gas cell under
the dense plasma condition. We measured the extraction yield as a function of the primary beam intensity,
as shown in Fig. 2, using the MRTOF-MS to identify

300
200
100
0
0

20

40

60

80

100

Primary beam intensity [pnA]

Fig. 2. Measured extraction yield of 198 Pt+ as a functionof the primary beam intensity.

and count 198 Pt2+ ions extracted from the gas cell.
The extraction eﬃciency from the gas cell was determined to be approximately 1%, indicating more than
one order of magnitude improvement over the argon
gas cell. Futhermore, the extraction yield increased
linearly in proportion to the primary beam intensity
up to at least 100 particle nA, in contrast with theperformance of the argon gas cell wherein yields typically saturate above 50 particle nA. In total, we expect
more than a 20-fold gain in extraction yield by using
the helium gas cell. We plan to measure the massesof unstable nuclei in the vicinity of N = 126 with thissystem in the near future.
References
1) Y. Hirayama et al., Nucl. Instrum. Methods Phys. Res.
B 463, 425 (2020).
2) K. R. Lund et al., Nucl. Instrum. Methods Phys. Res.
B 463, 378 (2020).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Development of light collection system for collinear laser spectroscopy
M. Tajima,∗1 A. Takamine,∗1 H. Iimura,∗1 M. Wada,∗2 and H. Ueno∗1
The laser spectroscopy of atomic transitions can aid
in clarifying the nuclear structures in ground and isomeric states. We are preparing for the collinear laser
spectroscopy (CLS) of rare isotopes (RIs) at the upcoming thermalized RI beam facility using an He gas
catcher, referred to as SLOWRI.1) Barium isotopes
were measured as a ﬁrst oﬄine demonstration of our
CLS setup.2) Thereafter, oﬄine measurements of stable Zr isotopes were performed.3) An unstable refractory element isotope such as a radioactive Zr isotope isa candidate for an online experiment in the intermediate mass region. As the intensity of exotic Zr isotopes
is limited in the online experiment, the detection efﬁciency should be improved for precise measurement.
This report describes a next step to improve the lightcollection eﬃciency.
We have performed CLS by changing the velocity,that is, Doppler tuning, of the ion beam using postacceleration electrodes in the region where a photomultiplier tube (PMT) is placed as a ﬂuorescence monitor. Figures 1(a) and (b) depict the top and side viewsof the primary design of the electrodes, respectively.
Ion beams and the spectroscopy laser pass collinearlythrough them (from left to right). A post-acceleration
voltage up to ±3 kV is applied on a long electrode at
the center, divided by each resistor connected to eachthin electrode, and grounded at both ends. A sheet ofmetal mesh is attached on both sides at the center. It(e)Cylindrical mirror

avoids optical pumping outside of the region and enables the spectroscopy laser to be locked. Figure 1(e)presents a schematic around the center electrode. The
PMT is placed in front of the mesh and a cylindricalmirror is placed on the opposite side, so that light fromthese two open sides can be detected.
We constructed a new pair of mirror-shaped electrodes to improve the light collection eﬃciency. Figure 1(c) depicts the inner surfaces of the new electrodes:
one is spherical with a hole at the center (left) andthe other is ellipsoidal (right); these were originally designed by M. Baba4) for molecular spectroscopy. They
are made of aluminum, and the inner surfaces are polished. Figure 1(d) presents an integrated view with
the new pair of electrodes at the center. Figure 1(f)presents a schematic where blue and magenta dashedlines correspond to the ellipsoidal and spherical surfaces, respectively. The center of the spherical surface
is one of two simultaneous focal points of the ellipsoidal
surface. If a point-like light source is placed at thecenter, reﬂected light on the spherical surface returns
and re-passes the spherical center, and then re-reﬂected
light on the ellipsoidal surface focuses onto the otherfocal point, which is observed using the PMT throughthe hole. It allows 90% of solid angle coverage for the
pointlike source. In CLS, however, 40% of coverage isestimated when the interaction region is 4 cm in length.
We performed the CLS of 90 Zr+ this new apparatus.
The overall eﬃciency is improved by a factor of 2.3 over
the original detection setup. The absolute value is estimated at more than 4 × 10−6 , though it is necessary
to determine the exact number of ions that contributeto the optical detection. So far, a resonance peak was
observed for the intensity of down to 103 ions per bunchof repetition of 2 Hz, as depicted in Fig. 1(g). Further
improvement such as one-to-one coincidence with ion
detection is necessary to reduce the background rate
for the exotic RIs with intensity lower than 100 pps.
Further, the reﬂectivity of the surface of the electrodein this wavelength region, which is currently estimatedat less than 50%, can be improved up to 60% by polishing.5)
References

Fig. 1. Post-acceleration electrodes: (a) top and (b) sideview of the old ones, (c) inner surfaces, and (d) assembled view of the new ones. Schematics of the (e) previousand (f) new design of the center electrode. (g) Observed
spectrum of 90 Zr+ with 103 ions per bunch and Voigt
ﬁtting.
∗1∗21) M. Wada et al., Nucl. Instrum. Methods Phys. Res. B
204, 570 (2003).
2) M. Tajima et al., RIKEN Accel. Prog. Rep. 53, 15(2020).
3) M. Tajima et al., RIKEN Accel. Prog. Rep. 55, 90(2022).
4) M. Baba et al., J. Chem. Phys. 131, 224318 (2009).
5) K. Minamisono et al., Nucl. Instrum. Methods Phys.
Res. A 709, 85 (2013).

RIKEN Nishina Center
Wako Nuclear Science Center (WNSC), IPNS, KEK- 104 -

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Measuring the stopping position of the energetic radioactive Rbbeams in superﬂuid helium
M. Ito,∗1,∗2 K. Imamura,∗1 S. Akimoto,∗1,∗2 A. Takamine,∗1 K. Kikuchi,∗1,∗2 R. Mitsuyasu,∗1,∗2 T. Miwa,∗1,∗2
A. Gladkov,∗1 M. Tajima,∗1 S. Go,∗1 M. Mukai,∗1 H. Endo,∗1,∗2 S. Sasamori,∗1,∗2 S. Takahashi,∗1,∗2
Y. Fukuzawa,∗1,∗2 M. Hase,∗3 K. Kawata,∗1,∗4 A. Kitagawa,∗5 T. Wakui,∗5 H. Ueno,∗1 and Y. Matsuo∗1,∗2
We are developing a laser spectroscopy techniquecalled OROCHI (Optical RI-atom Observation in Condensed Helium as Ion-catcher) to study the nuclear
structure of short-lived and low-yield radioisotopes
produced at accelerator facilities.1) In OROCHI, ion
beams are injected into superﬂuid helium (He II),
where the ions are slowed down, stopped in a small
volume, and neutralized with nearly 100% eﬃciency.
Nuclear spins/moments are derived from the measurements of the Zeeman/hyperﬁne splitting energy using
the laser-radio frequency (RF)/laser-microwave (MW)double resonance. The feasibility of this method formeasuring the hyperﬁne splitting energy with an accuracy of six orders of magnitude was demonstrated
in oﬀ-line experiments conducted with Cs atoms.2)
Therefore, this method is expected to be promisingfor short-lived unstable nuclei applications.
In previous online experiments,1) our group observed laser-RF double resonance spectra for 84–87 Rb
ion beams provided by the RIKEN RIPS at∼60 MeV/nucleon. In the future, we plan to conduct
measurements on low-yield unstable nuclear atoms,
such as Ag, which are provided at energies as highas ∼300 MeV/nucleon at the RIKEN BigRIPS facility.
To demonstrate the applicability of our method to highenergy beams, we conducted experiments at the QSTHIMAC SB2 beamline, which can deliver a beam inexcess of 350 MeV/nucleon. Among the single-valenceelectron alkali atoms, Rb is one of the atoms whose
behavior in superﬂuid helium is well studied. Furthermore, 84 Rb is estimated to be produced with the highest yield with a primary beam of 84 Kr according to the
LISE++ simulation. This is why we employed 84 Rb as
the target atom in our experiments. Because the number of atoms stopped in the observation region in He
II is small, a LIF (laser-induced ﬂuorescence) detection
mechanism with high eﬃciency is needed. Therefore,
the accurate measurement of the beam stopping position at HIMAC SB2 beamline is one of the importantdevelopments for the future double resonance measurement of atoms with unstable nuclei.
So far, in FY2019, we measured the beam yields of ahigh-energy 84 Rb beam at the HIMAC SB2 beamline
∗1
∗2
∗3
∗4
∗5

RIKEN Nishina Center
Department of Advanced Sciences, Hosei University
National Institute for Materials Science (NIMS)
Center for Nuclear Study, University of Tokyo
Institute for Quantum Medical Science, National Institutes for Quantum and Radiological Science and Technology(QST-iQMS)- 105 -

using liquid nitrogen as a stopping material to estimate the number of stopped atoms in the possible LIF
observation region.3) Then, in FY2021, we successfully
observed the LIF of 84 Rb atoms in superﬂuid helium(He II) at the HIMAC SB2 beamline.4)
In FY2022, the number of measurement points wasincreased compared to the beam experiment conductedin FY2021 to more precisely determine the beam stopping position. Two measurement methods were performed as shown in Fig. 1. (1) measurement of thenumber of injected ions that penetrated the plastic
scintillator placed in the center of the cryostat in normal ﬂuid liquid helium and (2) measurement of LIF
from atoms stopped in superﬂuid helium in the cryostat. A taper-ampliﬁed laser light5) was used for theirradiation of the cryostat center with a cross section
size of 3 mm × 6 mm. These two types of measurements were performed while varying the thickness of
the Al degrader every 100 µm to optimize the degrader
thickness for eﬃcient LIF collection from 84 Rb atoms.
We are currently in the process of data analysis.

Fig. 1. Schematics of RI beam introduction to helium at
HIMAC SB2 beamline.

References
1) X. F. Yang et al., Phys. Rev. A 90, 052516 (2014).
2) K. Imamura et al., Hyperﬁne Interact. 73, 230 (2015).
3) K. Tsubura et al., RIKEN Accel. Prog. Rep. 53, 132(2020).
4) K. Tsubura et al., RIKEN Accel. Prog. Rep. 55, 91(2022).
5) R. Mitsuyasu et al., in the abstract of 25th Congress of
the International Commission for Optics (2022).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Highly-eﬃcient γ-ray linear polarization measurementby multi-layer CdTe Compton Camera
S. Go,∗1 Y. Tsuzuki,∗2,∗3,∗1 Y. Ichikawa,4,∗1 T. Ikeda,∗1 N. Imai,∗5 K. Imamura,∗1 M. Niikura,∗1
D. Nishimura,∗6,∗1 R. Mizuno,∗2,∗1 S. Takeda,∗3,∗1 H. Ueno,∗1 S. Watanabe,∗7,∗3,∗1 T. Y. Saito,∗5
S. Shimoura,∗5,∗1 S. Sugawara,∗6,∗1 A. Takamine,∗1 H. Yoneda,∗1 and T. Takahashi∗2,∗3,∗1

F = ϵQ2 ,(1)

where ϵ is the eﬃciency of the detector to measure
Compton-scattering events and Q is the polarization
sensitivity of the polarimeter. The development of the
γ-ray polarimeters which has a suﬃcient ﬁgure of meritis important for the linear polarization measurements
on rare isotopes.
Therefore, we implement a multi-layer semiconductor Compton Camera,2,3) which has been developed
originally for the X- and gamma-ray observatory inspace, for the linear polarization measurement. The
detector consists of 20-layer pixelated cadmium telluride. The thickness of each layer is 0.75 mm andthe eﬀective area of 51.2 × 51.2 mm2 is pixelated into
16 × 16. The detector measured the intensity distribution of Compton-scattering events of γ ray as a function of azimuth angle.
To demonstrate the capability of measuring the linear polarization for sub-MeV γ-ray, the experiment
was conducted at the RIKEN Pelletron facility in May
2022. The performance as a polarimeter was investigated with polarized γ-ray.4) The iron target foil of
10 µm was irradiated with the proton beam energy
around 3.1 MeV. The ﬁrst excited 2+ state of 56 Fe
was populated by the proton inelastic reactions. The
azimuth angle distribution of 847-keV γ ray were measured by the detector placed at 90◦ degrees to thebeam direction. The segmented Ge detector (CNSGRAPE5) ) with a lead collimator was also placed at
90◦ to the beam direction to measure the axial asymmetry of scattered radiation as described in Ref. 6).
The intensity distribution of Compton scattering
∗1
∗2
∗3
∗4
∗5
∗6
∗7

RIKEN Nishina Center
Department of Physics, University of Tokyo
Kavli Institute for the Physics and Mathematics of the Universe, Institutes for Advanced Study
Department of Physics, Kyushu University
Center for Nuclear Study, University of Tokyo
Department of Physics, Tokyo City University
Institute of Space and Astronautical Science, Japan
Aerospace Exploration Agency- 106 -

events as a function of azimuth angle obtained by theCompton Camera is shown in Fig. 1. The curve wasobtained by calculating the ratio of the experimental
and simulated azimuth angle intensity for polarized
and unpolarized photons, respectively. The known
electric character of the γ-ray was successfully conﬁrmed. Further analysis to quantify the polarization
sensitivity and ﬁgure of merit of the polarimeter is inprogress.

1.5
1.4
1.3
1.2

Ratio

Linear-polarization measurements of photons are
typically applied to determine the electromagnetic
character of gamma-ray transitions. However, themeasurement has not been applied in the wide range of
nuclei because it needs to measured the azimuth andpolar scattering angle of Compton Scattering events.
As for the performance for the polarimeter, a ﬁgure of
merit was proposed as:1)

1.1
1
0.9
0.8
0.7
0.6
0.5

3

2

1

0

1

2

3

Azimuth angle (rad)Fig. 1. Intensity distribution of Compton scattering eventsof the 847-keV γ-ray as a function of azimuth angle.

References
1) B. A. Logan et al., Nucl. Instrum. Methods Phys. Res.
108, 603 (1973).
2) T. Takahashi, Nucl. Phys. B (Proc. Suppl.) 134, 191(2004).
3) S. Watanabe et al., Nucl. Instrum. Methods Phys. Res.
A 505, 118 (2003).
4) J. Simpson et al., Nucl. Instrum. Methods Phys. Res.
204, 463 (1983).
5) S. Shimoura et al., Nucl. Instrum. Methods Phys. Res.
A 525, 188 (2004).
6) P. A. Butler et al., Nucl. Instrum. Methods Phys. Res.
108, 497 (1973).

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Charge-exchange reaction of francium ions using an yttrium
neutralizer
H. Nagahama,∗1 K. Nakamura,∗1 N. Ozawa,∗2 M. Sato,∗3,∗4 T. Nakashita,∗3,∗4 S. Nagase,∗2 M. Fukase,∗2
D. Uehara,∗2 Y. Kotaka,∗1 K. Kamakura,∗1 T. Aoki,∗4 H. Haba,∗3 A. Takamine,∗3 H. Ueno,∗3 and Y. Sakemi∗1

∗1
∗2
∗3
∗4

Center for Nuclear Study, University of Tokyo
Department of Physics, University of Tokyo
RIKEN Nishina Center
Graduate School of Arts and Sciences, University of Tokyo- 107 -

for 1.5–2 hours to clean its surface.
Figure 1 shows an example of count rate of alphaparticles emitted via the alpha decay of 208–211 Fr detected by an SSD, as a function of time. By evaluating
all the data collected during the beam time, we derived
a desorption eﬃciency of ϵdes = 29 ± 15%, when the
foil was heated to 750◦ C for approximately 3 seconds.
Considering an experiment to measure the desorptionenergy of rubidium (Rb) on a Y surface,4) almost all
the Fr on the surface should be released into the vacuum by heating the foil up to 350◦ C for several seconds. Note that Rb is an alkali element akin to Fr andhas chemical properties similar to those of Fr. This
discrepancy implies that the cleaning procedure of the
Y surface before the measurement was insuﬃcient torealize an ideal surface, which does not have any impurities nor passive layers.
5000
SSD count rate

The large imbalance in the amounts of matter andantimatter currently observed in the universe demands
physics beyond the standard model, which violates fundamental symmetries.1) Recently, the search for a nonzero permanent electric dipole moment (EDM) of an elementary particle has taken place actively world-wide,
because the existence of EDM violates charge conjugation parity symmetry.
It is predicted that the EDM of an electron (eEDM)
is enhanced in paramagnetic atoms.2) Francium (Fr),being the heaviest alkali element, is known to possess the largest eEDM enhancement factor amongst
any ground-state atom.3) Therefore, we aim to search
for the eEDM with unprecedented precision using Fr
atoms trapped in an optical lattice. To achieve thisgoal, it is necessary to prepare a large number of Fr
atoms trapped in a magneto-optical trap (MOT) before transporting them to an optical lattice. The number of trapped atoms in a MOT strongly depends onthe desorption eﬃciency of Fr atoms from a neutralizer, where the charge-exchange reaction of Fr ionstakes place. Here, we report the characterization of
the eﬃciency of Fr atoms desorbed from an yttrium(Y) neutralizer during beam time in 2022.
An 18 O6+ beam (7 MeV/nucleon) provided by the
AVF cyclotron in RIKEN RIBF is irradiated on thegold target to induce the following fusion reactions:
197
Au(18 O, xn)215−x Fr. Heating up the target using
an infrared radiation heater results in thermal diﬀusionof the produced Fr, and some fractions will reach thesurface. Subsequently, most of the Fr on the surface
will be thermally ionized and extracted as a secondary
beam (100 eV, typically 5 × 106 s−1 for 210 Fr). The
Fr ions are transported through the electrostatic beamline and irradiated on a Y foil for 3 minutes. The Y
foil is then moved mechanically to the so-called silicon
semiconductor detector (SSD) chamber to characterize the number of Fr atoms deposited on the surfaceof the foil. After the characterization, the foil is transported to the so-called neutralization chamber to heat
the foil up to a maximum of 750◦ C and release the Fr as
neutral atoms into a vacuum. Finally, the foil is transported back to the SSD chamber to characterize thenumber of Fr atoms remaining on the surface. Before
conducting this experiment, the Y foil is bombarded byan argon (Ar) ion beam (10−2 A m−2 , 500 eV, 300 K)

heating
procedure

1000
500
100
50
10

0

50

100

150

200

Time (s)Fig. 1. Count rate of alpha particles emitted via alpha decay of 208–211 Fr detected by a silicon semiconductor detector (SSD), as a function of time.

In 2023, we are planning to realize an ideal Y surface
by optimizing the sputtering procedure using the Ar
ion beam and by annealing the Y foil to reconstruct
the surface structure. Consequently, this will allow themore eﬃcient release of Fr on the surface at a minimum
heating temperature, which will enable us to maximize
the MOT eﬃciency of the Fr atoms.
References
1) A. D. Sakharov, Sov. Phys. Usp. 34, 392 (1991).
2) M. Popeslov et al., Annu. Phys. 318, 119 (2005).
3) N. Shitara et al., J. High Energy Phys. JHEP02, 124(2021).
4) M. P. Cox et al., Surf. Sci. 129, 375 (1983).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Absorption spectroscopy measurements of molecular iodine formagneto-optical trapping of francium atoms
K. Nakamura,∗1 S. Nagase,∗2 T. Nakashita,∗3,∗4 T. Hayamizu,∗4 T. Aoki,∗3 H. Nagahama,∗1 N. Ozawa,∗2
M. Sato,∗3,∗4 M. Fukase,∗2 D. Uehara,∗2 A. Takamine,∗4 and Y. Sakemi∗1
We have demonstrated absorption spectroscopy
measure-ments of molecular iodine (I2 ) to develop a permanent electric dipole moment (EDM) measurement system with 210 Fr atoms in E7 and 221 Fr atoms in the hotlab. Laser cooling of the atoms makes it possible toelongate the interaction time in the EDM measurement.
During a few years, the number of Fr atoms produced
has been gradually improved toward the realization of
the MOT. The laser frequency used to trap the atoms
has to be red-detuned by several tens of MHz from theresonance frequency of the trapping transition (7S1/2
F = 13/2 → 7P3/2 F = 15/2 for 210 Fr, 7S1/2 F = 3 →7P3/2 F = 4 for 221 Fr). The frequency range where theatoms can be trapped is ∼10 MHz.1) We have used thehigh performance wavelength meter (HighFinesse, WS82) with an absolute frequency accuracy of 10 MHz tosearch for the appropriate frequency for MOT by varying the laser frequency in the vicinity of the Fr trapping transition frequencies reported by previous studies,1–4) but have not yet achieved MOT. The frequency
references that they rely upon and the wavelength meterthat we rely upon are diﬀerent and not traceable. The
Fr trapping transition frequencies with references to theI2 absorption lines have been reported.1,2) In this study
we perform I2 absorption spectroscopy and discuss the
Fr trapping transition frequencies based on the results
obtained.
The experimental setup for I2 absorption spectroscopy
is shown in Fig. 1(a). In this spectral region, the I2cell must be heated above 570 K to observe the absorption well.1) It has been reported that the 210 Fr trapping
laser frequency (−31 MHz detuning3) ) is +3.38(8) GHz
away from the I2 Doppler broadened P(78)1-9 transition (commonly known as atlas5) line number 381)
frequency1) whereas the 221 Fr trapping transition frequency is −0.5(1) GHz away from the I2 Doppler broadened R(113)3-10 transition (atlas5) line number 380) frequency2) (Fig. 1(b)). However, these studies do not describe the cell temperature. The I2 absorption spectrum
is a composite of several Doppler broadened hyperﬁne
structure spectra.6) Therefore, the peak frequency of theI2 absorption spectrum may shift at diﬀerent cell temperatures. We performed absorption spectroscopy of line
numbers 380 and 381 at cell temperatures T = 570, 590,
610, and 630 K, respectively. The absolute frequencyof line 381 (T = 590 K) was 417 409 191(10) MHz,
that is, −57 MHz away from the I2 atlas [417 409
248(57) MHz].5) Whereas, that of line 380 (T = 570 K)
∗1
∗2
∗3
∗4

Center for Nuclear Study, University of Tokyo
Department of Physics, University of Tokyo
Graduate School of Arts and Sciences, University of Tokyo
RIKEN Nishina Center

Fig. 1. (a) Experimental setup for I2 absorption spectroscopy.
(b) I2 lines and Fr trapping transition frequencies. Trapping transition frequencies of (c) 210 Fr and (d) 221 Fr, respectively.

was 417 400 090(11) MHz, that is, +40 MHz away fromthe I2 atlas [417 400 050(51) MHz].5) The trapping transition frequencies for 210 Fr and 221 Fr reported by previous studies are shown in Figs. 1(c)–(d). They used
I2 atlas,1) wavelength meter,2,3) and optical resonator4)
as frequency reference, respectively. Ref. 2) states thatthe absolute frequency of the I2 380 line was +30 MHz
away from the atlas5) with reference to their wavelength
meter. Consequently, the present I2 absorption spectroscopy found that the Fr trapping transition frequencies shown in Refs. 1) and 2) were shifted by −57 MHz(T = 590 K) and +10 MHz (T = 570 K), respectively,
when using our wavelength meter as the frequency reference (red dots in Figs. 1(c)–(d)). Depending on thecell temperature, the center frequency of the absorption spectrum was shifted by up to 28 MHz (No. 381)
and 31 MHz (No. 380), respectively. Till date, we haveused the frequency range in the blue dashed rectangular (Figs. 1(c)–(d)) as the expected frequencies in MOT
searches; however, they must be extended further.
References
1) J. E. Simsarian et al., Phys. Rev. Lett. 76, 3522 (1996).
2) Z. -T. Lu et al., Phys. Rev. Lett. 79, 994 (1997).
3) E Gomez et al., Rep. Prog. Phys. 69, 79 (2006).
4) S. Sanguinetti et al., Opt. Lett. 34, 893 (2009).
5) S. Gerstenkorn et al., Atlas Du Spectre D’Absorption De
la Molecule D’Iode (Laboratoire Aime Cotton, Orsay,
France, 1982).
6) P. Dubé et al., J. Opt. Soc. Am. B 21, 1113 (2004).

- 108 -

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Improved 6 He beam production at CRIB with MWDC and degraders
H. Yamaguchi,∗1 M. Sferrazza,∗2 S. Hayakawa,∗1 K. Okawa,∗1 Q. Zhang,∗1,∗3 S. Cherubini,∗4 M. La Cognata,∗4
R. G. Pizzone,∗4 T. Chillery,∗1 S. Hanai,∗1 N. Imai,∗1 S. Masuoka,∗1 and K. Yako∗1

∗1
∗2
∗3
∗4

Center for Nuclear Study, University of Tokyo
Department of Physics, Université Libre de Bruxelles
Department of Physics, Lanzhou University
Laboratori Nazionali del Sud, Istituto Nazionale di Fisica
Nucleare (INFN)- 109 -

No degrader-30

Normalized counts

The ﬁrst production test of 6 He beam at CRIB was
performed in 2021,1) in which 6 He beams at two different energies (8.0 and 5.7 MeV/nucleon) were successfully produced with an intensity of the order of
105 –106 pps. However, the practical beam intensity
was limited to ∼ 2 × 105 pps due to the low detection eﬃciency of the PPAC for such a light-ion beam.
The 6 He beam purity was 73% for the 8 MeV/nucleon
beam, where the main contaminant was 3 H1+ , having
an almost identical charge-to-mass ratio as 6 He2+ .
The second test was carried out in Oct. 2022 as a
two-day machine study (MS-EXP22-05), to improvethe eﬀective intensity and purity of the 6 He beam byintroducing wire chambers (MWDC2) ) and degraders.
The primary beam was 7 Li3+ accelerated with the AVF
cyclotron to an energy of 8.3 MeV/nucleon, and the
RI beam was produced with the 7 Li(d, 3 He)6 He reaction in inverse kinematics. The major diﬀerences fromthe ﬁrst test were the maximum 7 Li beam current of
1.5 particle µA (= 4.4 electric µA) at the entranceof CRIB and the pressure of the production target(around 410 Torr), which were both lower than theprevious values (3 particle µA and 730 Torr, respectively).
To purify the 6 He beam, we installed degraders withtwo diﬀerent thicknesses (10-µm-thick aluminized and20-µm-thick normal Mylar ﬁlms) at the F1 (momentum dispersive) focal plane. We conﬁrmed a position
oﬀset between 6 He and 3 H was produced at F2 witheach degrader, as shown in Fig. 1. Using the 20-µmthick degrader, the beam purity at F3 measured witha plastic scintillator was 91%, much improved from theprevious value, 73%.
The MWDC had already been developed and usedat CNS for SHARAQ/OEDO experiments,2) and introduced for the ﬁrst time at CRIB. In the present
test, we employed two MWDCs operated at 10 kPa(76 Torr), having an XX-YY anode conﬁguration andcell sizes of 3 mm and 5 mm for the upstream anddownstream ones, respectively. Even with a high-ratesecondary beam at 6.0 × 105 pps, the MWDCs maintained an eﬃciency ϵ > 90% with high voltages of up
to 900 V, and no signiﬁcant reduction of the eﬃciency
was observed. This is in contrast to the previous test,
where we had to limit the primary beam current to
0.3 particle µA in order to keep the stable PPAC operation with an acceptable eﬃciency (ϵ = 70%). The

-20

-10

10 m Mylar

-30

-20

20 m Mylar

-30

-20



3H

6He

0

10

0

10

20

30

3H

6He

-10

30

3H

6He

-10

20

0

10

20

30

Beam position at F2 (mm)Fig. 1. The beam proﬁles of 6 He (solid line) and 3 H (dashedline), with diﬀerent degrader settings. The counts are
scaled to show the proﬁles as similar heights.

basic beam parameters are summarized in Table 1 andcompared with those of the optimum case in the previous test. The new 6 He rate is roughly consistent with
Table 1. Summary of the basic beam parameters. ϵ is theeﬃciency of the beam-monitoring detector.
7
6
Test
Li
F0 Pres. ϵ
He 6 He rate
year (particle µA) (Torr)
purity (kcps)
2021
0.3
730
70% 73%
200
2022
1.5
410
94% 91%520

the previous value, considering the higher 7 Li beam
current (×5) and nearly half F0 pressure. However,the previous rate (200 kcps) was severely limited with
the PPAC, while in the present work we successfully
obtained a higher 6 He rate (520 kcps) with a betterbeam purity (91%), even though the F0 pressure was
not at its best value. The new condition well satisﬁes
the requirements by the approved experiments,3) to be
performed in the near future.
References
1) H. Yamaguchi et al., RIKEN Accel. Prog. Rep. 55, 94(2022).
2) H. Miya et al., Nucl. Instrum. Meth. Phys. Res. B 317,
701 (2013).
3) M. Sferrazza et al., proposal for RIBF NP-PAC-21,
NP2021-AVF70 (2020, unpublished) and others.

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Progress on double photon coincidence imaging with 67 Cu and 169 Yb
K. Shimazoe,∗1 M. Uenomachi,∗2 H. Takahashi,∗1 Y. Shigekawa,∗3 A. Nambu,∗3 X. Yin,∗3 and H. Haba∗3
In nuclear medical imaging, positron emission tomography (PET) and single photon emission computed tomography (SPECT) are two important imaging modalities; however, the imaging principles of these modalities
have remained the same for more than 50 years. We haveproposed and investigated a novel imaging method referred to as double photon emission coincidence imaging(DPECI) utilizing two successive gamma-rays emitted
from cascade nuclides.1,2) The coincidence detection of
two gamma-rays enables the localization of radioisotope
with a single event. Previous studies have shown theincrease in signal to noise ratio (SNR) and reduction ofcross-talks between nuclides through the application of
selection with timing information using 111 In and 177 Lu,
which are clinically used radioisotopes for diagnosis andtherapy.3,4) Furthermore, in addition to the conventional
accumulation imaging of radioisotope, the hyperﬁne interaction of intermediate state in cascade nuclides withthe external ﬁeld can be used to detect the chemical information using the successive gamma-ray photons asreported in previous studies.5,6)
Here we investigate the possible use of 67 Cu and 169 Yb
for DPECI with collimator-based imaging system. 67 Cu
and 169 Yb were produced in the 70 Zn(d, αn)67 Cu and169
Tm(d, 2n)169 Yb reactions at the RIKEN AVF cyclotron. 67 Cu emits two gamma-rays with energies of
91.3 and 93.3 keV with the time constant of 9.1 µs in acascade decay. 169 Yb also emits two gamma-rays withthe combination of 63.1–177 keV, 63.1–198 keV, and
63.1–307.7 keV in cascade decays and the time constantis approximately 659.9 ns. The relatively long intermediate time constant could be useful to detect the hyperﬁneinteraction through the gamma-ray distribution. In thisstudy, we demonstrate DPECI method using the combination of slit and parallel-hole collimators achieving
higher sensitivity than parallel-hole only collimators using 67 Cu.7)
Figure 1 shows the experimental setup of DPECI to visualize 67 Cu radioisotope using the coincidence detectionof two gamma-rays. 67 Cu with the activity of 2.12 MBq
was enclosed in the U-shape phantom and measured for
16 hours. The time window was set to 10 µs. The shapeof U is successfully visualized by considering the intersection of a plane determined by slit collimators anda line by parallel-hole collimators. The slit width ofcollimator was 1.6 mm with thickness of 15 mm. The
gamma-rays were detected by 2.5 mm × 2.5 mm × 4 mm
(D) HR-GAGG scintillation crystals arrays coupled to
SiPM arrays.
For evaluating the feasibility of coincidence detection of two successive gamma-rays from 169 Yb, ring∗1∗2∗3School of Engineering, University of Tokyo
Unit of Synergetic Studies for Space, Kyoto University
RIKEN Nishina Center

Fig. 1. Geometry of DPECI for visualizing 67 Cu radioisotope
enclosed in U shape phantom and its image.

shape GAGG-SiPM detector arrays including 512 channels were used. The left panel in Fig. 2 shows the time
diﬀerence between two gamma-rays and the decay time
constant of 659.9 ns is successfully observed. The rightpanel shows the energy spectrum obtained from the timeover-threshold (ToT) measurement, which indicates thatthe gamma ray energy is correctly identiﬁed.

Fig. 2. Coincidence time histogram of two gamma-rays from169
Yb and the measured energy spectra with GAGGSiPM arrays.

In summary, we have proposed a new method(DPECI) using double photon emitting nuclides and theimaging capability and coincidence detection was demonstrated with 67 Cu and 169 Yb fabricated at RIKEN AVF
cyclotron.
References
1) K. Shimazoe et al., J. Instrum. 12, C12055 (2017).
2) M. Uenomachi et al., Bull. Am. Meteorol. Soc. 18, 120(2022).
3) M. Uenomachi et al., Sci. Rep. 11, 13330 (2021).
4) M. Uenomachi et al., J. Instrum. 17, P04001 (2022).
5) K. Shimazoe et al., Commun. Phys. 5, 1 (2022).
6) K. Shimazoe et al., Bull. Am. Meteorol. Soc. 18, 127(2022).
7) L. Yan et al., Nucl. Instrum. Methods Phys. Res. A 1053,
168305 (2023).

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Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Status of the J-PARC E16 experiment in 2022
S. Yokkaichi∗1 for the J-PARC E16 Collaboration
We proposed the experiment E161) to measure thevector meson decays in nuclei in order to investigate
the chiral symmetry restoration in dense nuclear matter. The experiment started at the J-PARC Hadron
Experimental Facility.
This experiment aims to systematically study thespectral modiﬁcation of vector mesons in nuclei, particularly the ϕ meson, using the e+ e− decay channel
with statistics that are two orders larger in magnitude
than those of the prior E3252) experiment performed at
KEK-PS. In other words, it aims to accumulate 1 ×105
to 2×105 events for each nuclear target (H, C, Cu, andPb) and deduce the dependence of the spectral modiﬁcation on the size of nucleus and meson momentum.
The number of modiﬁed mesons could be larger forlarger nucleus and lower momentum mesons because
the decay probability inside the nucleus is enhanced
for such cases.
The proposed spectrometer comprises 26 modules.
As shown in Fig. 1, a module consists of Lead-glass
calorimeter (LG) and Hadron-blind detector (HBD)
for electron identiﬁcation, as well as three-layers of
GEM Trackers (GTR) and a single layer of silicon strip
detector (SSD) as the tracking devices.

Fig. 1. Cross-sectional plan view of the E16 spectrometerin the eight-module conﬁguration for Run-1.

Commissioning runs, in total 403 hours as summarized in Table 1, were performed in 2020-21 at the
newly constructed ‘High-momentum beam line’.3) Owing to budget limitations, a limited number of modules were installed in the commissioning runs. In
these runs, electron identiﬁcation performance was
conﬁrmed.4) The read out circuit for the data collection is described in Ref.5)
In the next beam time planned in 2023, full eight
modules shown in Fig. 1 will be operated. In the previous runs, six modules of SSD was borrowed from
J-PARC E07 group. However, they will be replaced∗1

Table 1. Run-time summary.
prospect.

Run-0a Run-0b
Run-0c Total
2020
2021
2021
Period
6/4-20 2/11-28 5/28-6/9
Days
17
18
12
47
Beam time (h)
159
110
134
403
Raw data (TB)
33
28
46
97

- 111 -

Run-0d
2023
(5-6)
100
-

by the newly developed eight modules with the cooperation of the CBM group at GSI.
The major issue detected in the commissioning runs
is the micro beam structures, which deteriorate theDAQ performance3) due to the time-localized highbeam intensity. It was typically ten times as highas the nominal value of the beam intensity. In otherwords, the typical beam rate is 5 GHz because the intensity is 1 × 1010 protons per 2 sec duration; however,
the actual beam rate increased to 50 GHz locally due
to the micro structures.
Some countermeasures have been discussed and will
be applied in the next beam time. Before Run-1(physics run), we plan to perform a beam study tocheck whether the countermeasures can improve theDAQ performance, and construct the acceptable trigger rate by tuning threshold, coincidence pattern andtime window, and beam intensity, with the upgraded
DAQ system.
In Aug. 2022, our proposal for Run-1 based on the
updated technical design report was reviewed. The
approval for Run-1 was deferred, and only 200 hours
of beam time was approved for the beam study (101hours) and trigger study (100 hours) as mentioned
above.
In J-PARC, an upgrade work of MRa) was performed
from 2021 summer (just after the Run-0c) to 2022 autumn, and a test operation of MR had started. Owing
to the malfunction of the septum magnet and so on, we
expect the next beam time, namely, a slow extraction
beam for users, in May 2023 at the earliest case.
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); M. Ichikawa et al., Acta
Phys. Pol. B Proc. Suppl. 16, 1-A143 (2023).
2) R. Muto et al., Phys. Rev. Lett. 98, 042501 (2007).
3) S. Yokkaichi, RIKEN Accel. Prog. Rep. 55, 54 (2022).
4) S. Nakasuga et al., Nucl. Instrum. Methods Phys. Res.
A 1041, 167335 (2022).
5) T. N. Takahashi et al., IEEE Trans. Nucl. Sci. 68, 1907
(2021).
a)

RIKEN Nishina Center

Run-0d demonstrates

J-PARC Main Ring Accelerator

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Preparation status for sPHENIX experiment and INTT detector for
Run23 at RHIC
I. Nakagawa,∗1 Y. Akiba,∗1 J. Bertaux,∗2 K. Fujiki,∗1,∗3 M. Fujiiwara,∗4 T. Hachiya,∗1,∗4 S. Hasegawa,∗1,∗5
M. Hata,∗4 H. Imai,∗1,∗3 M. Kano,∗4 T. Kato,∗1,∗3 T. Kondo,∗6 C. M. Kuo,∗7 R. S. Lu,∗8 Y. Namimoto,∗1,∗4
R. Nouicer,∗9 G. Nukazuka,∗1 C. W. Shih,∗7 M. Shimomura,∗4 R. Shishikura,∗1,∗3 M. Stojanovic,∗2
Y. Sugiyama,∗4 R. Takahama,∗1,∗4 W. C. Tang,∗7 H. Tsujibata,∗4 M. Watanabe,∗4 and X. Wei∗2
The sPHENIX experiment is the next generation jet
detector which is under construction at RHIC as the
upgrade of former PHENIX experiment.1) The installation of a time projection chamber (TPC) detector
has been completed by the middle of January, 2023 asshown in Fig. 1. The silicon strip intermediate (INTT)
detector, developed by mainly Japanese group,2) is tobe implemented next inside of the TPC. The assembly of the INTT silicon ladders has been completed by
Spring of 2022.

Fig. 1. Installed TPC in the sPHENIX detector.

The barrel type INTT detector consists of the innerand outer layers of INTT ladders. Shown in Fig. 2 isthe pair of an INTT half barrel. 24 and 32 ladders were
installed as the inner and outer barrels, respectively.
The signal readout response of every single ladder wastested before and after the barrel construction using
a built-in calibration system which injects an artiﬁcial
pulse to an analogue to digital conversion chip implemented right next to the silicon sensors. The INTT
detector is scheduled to be installed to sPHENIX in
March 2023.
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteCenter for High Energy and High Field Physics and Department of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory- 112 -

Fig. 2. INTT half barrels.

A µ-coax technology (Fig. 3) was employed as thelast piece of the readout cable series3) for the INTT
ladder. This technology has certain advantage in the
ﬂexibility for a high signal density cable compared to
the ﬂexible print cable (FPC) one. On the other hand,a material “ﬂuorinated resin” used as an insulator forthe µ-coax harness is known to be weak against radiation compared to popular insulator materials likepolyimide or liquid crystal polymer which are typicallyused for the FPC4) Therefore the radiation hardness ofthe µ-coax harness was examined at RANS facility at
RIKEN. The harness was exposed to the RANS neutron beam upto 4 × 1012 equivalent neutrons which isan order of more dose than expected during the INTT
operation within 3 years of sPHENIX running. The
signal transmission performance was compared before
and after the irradiation. No degradation was observed
due to the radiation as a result.

Fig. 3. Readout cables for the INTT ladder based on theµ-coax technology.

References
1) Technical Design Report of sPHENIX (2019),
https://indico.bnl.gov/event/7081/ .
2) Nikkei Science, June (2023).
3) Trans. Jpn. Inst. Electron. Packag. 15, E21-007 (2022).
4) L. Whinnery et al., SAND2017-9103C (2017),
https://www.osti.gov/servlets/purl/1467983 .

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Preliminary results of INTT beam test 2021 at ELPH†
C. W. Shih,∗1 Y. Akiba,∗2 J. Bertaux,∗3 K. Fujiki,∗2,∗4 M. Fujiiwara,∗5 T. Hachiya,∗2,∗5 S. Hasegawa,∗2,∗6
M. Hata,∗5 H. Imai,∗2,∗4 M. Kano,∗5 T. Kato,∗2,∗4 T. Kondo,∗7 C. M. Kuo,∗1 R. -S. Lu,∗8 I. Nakagawa,∗2
Y. Namimoto,∗2,∗5 R. Nouicer,∗9 G. Nukazuka,∗2 M. Shimomura,∗5 R. Shishikura,∗2,∗4 M. Stojanovic,∗3
Y. Sugiyama,∗5 R. Takahama,∗2,∗5 W. -C. Tang,∗1 H. Tsujibata,∗5 M. Watanabe,∗5 and X. Wei∗3
The Intermediate silicon Tracker, INTT, is one
among the sub-detectors of sPHENIX tracking system.1) A beam test experiment was performed with
INTT ladders at the end of 2021 at ELPH, Japan.
In the experiment, a telescope of 4 INTT ladders was
installed, and 3 ladders were operated. The positron
beam with the energy of 1 GeV was delivered. Oneof the goals of this experiment was to demonstrate thedetection eﬃciency of INTT ladder. As the radiation
length of INTT ladder was 1.08% X0 , the track was
assumed to be a straight line.
This study focused on the column with the highest
events.2) The clustering was performed on 3 ladders,the adjacent ﬁred channels in a column were grouped
to form a hit cluster. The cluster position y in vertical direction was determined by y = Σi Ei · yi /Σi Ei ,where E is the energy deposit. The track reconstruction was performed by the upstream ladder, L0, anddownstream ladder, L2, and the detection eﬃciency ofthe middle ladder, L1, was measured. In the reconstruction process, no cluster in the adjacent columnsof all ladders was required, and the number of clusters was required to be one on the same column forL0 and L2. The tracks passing the criteria were considered as track candidates. The residual r is deﬁned
as r ≡ (y + Cy ) − ypred , where ypred is the y positionat L1 predicted by the track candidate, and Cy is an
oﬀset term indicating the misalignment. An alignment
correction of −Cy was applied in the study.
Several cuts were applied to maximize the authenticity of the results. For L0 and L2, the single-hit cluster was rejected to minimize the false track candidates
based on accidental noise hits. The track candidates
within ﬁve channels from the edges were rejected tosuppress the misalignment eﬀect (edge eﬀect). In addition, the track candidates with large deviation in theangle (±0.01 radian) from the beam axis were excluded(Slope cut). The track candidates that passed all criteria were considered as good tracks. Subsequently, theclusters in L1 were checked. Three categories were con†

∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

Condensed from the article in ELPH Annu. Rep. (2022)
Center for High Energy and High Field Physics and Department of Physics, National Central University
RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteDepartment of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory

sidered:(1) The closest cluster is close to ypred (Ngood ),(2) The closest cluster is far from ypred (Nfar ),(3) No cluster was found (Nno hit ).
The residual distribution of the ﬁrst two categories isshown in Fig. 1. The ﬁrst category requires |r| <0.234 mm (Residual cut).

Fig. 1. Residual distribution in L1.

The equation of detection eﬃciency of L1 is deﬁned
N
as Nno hit +Ngood
×100%. The systematic uncertaingood +Nfar
ties associated with the detection eﬃciency originate
from the determinations of the three cut values, theslope cut, edge eﬀect, and residual cut. Scanning
cut values provides the variation of each source, andthe variation average estimates the uncertainties. The
numerical values are summarized in Table 1.
Table 1. Sources of the systematic uncertainties aﬀecting
the detection eﬃciency calculation.
Sources
Residual cut
Slope cutEdge eﬀect
Total

Scan range
0.164–0.304 mm
0.0088–0.0112 radian
0–10 channels

Uncertainty (%)
0.063
3e-3
4e-4
0.063

Considering the systematic uncertainty, the detection
eﬃciency of ladder L1 was 99.33 ± 0.04 (stat) ±0.06(syst)%. The performance of INTT ladder is excellent
enough for the sPHENIX experiment.
References
1) Conceptual Design Report of sPHENIX (2018).
2) G. Nukazuka et al., ELPH Annu. Rep. (2022).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Accelerator report INTT onlmon progress summary 2023
J. Bertaux,∗2 Y. Akiba,∗1 K. Fujiki,∗1,∗3 M. Fujiiwara,∗4 T. Hachiya,∗1,∗4 S. Hasegawa,∗1,∗5 M. Hata,∗4
H. Imai,∗1,∗3 M. Kano,∗4 T. Kato,∗1,∗3 T. Kondo,∗6 C. M. Kuo,∗7 R. S. Lu,∗8 I. Nakagawa,∗1 Y. Namimoto,∗1,∗4
R. Nouicer,∗9 G. Nukazuka,∗1 C. W. Shih,∗7 M. Shimomura,∗4 R. Shishikura,∗1,∗3 M. Stojanovic,∗2
Y. Sugiyama,∗4 R. Takahama,∗1,∗4 W. C. Tang,∗7 H. Tsujibata,∗4 M. Watanabe,∗4 and X. Wei∗2
The sPHENIX OnlMon framework is designed to facilitate the monitoring of detector subsystems during
data collection. Raw data is continuously unpacked
and used to maintain ROOT1) histograms stored on aserver. A client can request these histograms and use
them to convey information to a user via a graphical interface, also generated using ROOT.1) Each subsystemof the sPHENIX experiment is responsible for implementing the unique methods needed for its framework.
The Intermediate Silicon Tracker (INTT) subsystem’s implementation must be suﬃciently comprehensive to show the readout status of the smallest partitions of its active area, yet compact enough so that auser can diagnose any issue at a glance. The hardwareof the INTT is organized into four concentric layers of
12, 12, 16, 16 ladders (innermost layer to outermost
layer). Each ladder is divided into north and south
halves, and each half-ladder has 26 chips arranged in 2
rows of 13. Each chip has 128 channels which can further specify an analogue to digital conversion (ADC)
value ranging 0 to 7. This is too much to show concurrently, and the compromise is to have multiple typesof displays.
The GUI has two types of displays: a main display that shows the INTT at the level of individual
chips, and a secondary display that will show an individual chip at the level of channels or ADC values.
The main display exhibits four histograms, representing each layer, with a bin for each chip. The bin will
be colored depending on a user speciﬁed option, suchas the raw number of counts registered to the chip, aweighted-average ADC value, or the number of channels exhibiting statistically signiﬁcant behavior whencompared to others at similar pseudorapidity (Fig. 1).
From the main display, a user can click a bin tolaunch a second GUI that shows a single histogram representing the chip, with bins for each channel and possibly ADC value, again colored by the same user speciﬁed option, the raw number of counts in each channel,
∗1
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteCenter for High Energy and High Field Physics and Department of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory- 114 -

Fig. 1. A primary GUI where bin values are the number ofstatistically signiﬁcant channels (see Fig. 2) in the chip
the bin represents. In this case, there are only 12 chips
with at least one signiﬁcant channel (the yellow bins).
Thick, black lines denote ladders and their north/south
halves, thin dotted lines denote chips, a key shows thechip layout in one ladder, and text shows which chip
the user’s mouse is over.

the exact ADC distribution across all channels, or the
likelihood of an issue with the channel based on its
comparative performance (Fig. 2).

Fig. 2. A secondary GUI where bin values are the statistical signiﬁcance (z-score) of the channel it represents
when compared to all channels at similar pseudorapidity. Here, any z < −2 or z > +2 is considered signiﬁcant and will be colored diﬀerently; in this case, there
is only one (the yellow bin). Text at the bottom shows
which channel the user’s mouse is over.

Reference
1) R. Brun and F. Rademakers, Nucl. Instrum. Methods
Phys. Res. A 389, 81 (1997).

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Performance of a new operating system by FELIX board for INTT insPHENIX
G. Nukazuka,∗1 Y. Akiba,∗1 J. Bertaux,∗2 K. Fujiki,∗1,∗3 M. Fujiiwara,∗4 T. Hachiya,∗1,∗4 S. Hasegawa,∗1,∗5
M. Hata,∗4 H. Imai,∗1,∗3 M. Kano,∗4 T. Kato,∗1,∗3 T. Kondo,∗6 C. M. Kuo,∗7 R. S. Lu,∗8 I. Nakagawa,∗1
Y. Namimoto,∗1,∗4 R. Nouicer,∗9 C. W. Shih,∗7 M. Shimomura,∗4 R. Shishikura,∗1,∗3 M. Stojanovic,∗2
Y. Sugiyama,∗4 R. Takahama,∗1,∗4 W. C. Tang,∗7 H. Tsujibata,∗4 M. Watanabe,∗4 and X. Wei∗2
sPHENIX is scheduled to start operationsn at theRelativistic Heavy Ion Collider at Brookhaven National
Laboratory in 2023 to study quark-gluon plasma andcold-QCD.1) The Intermediate Tracker (INTT) is a silicon barrel tracker located between the other two tracking detectors of the sPHENIX detector complex. INTT
is responsible for tracking and jet ﬂavor tagging withhigh precision and low background. It inherits muchof the electronics, such as the readout card (ROC),
from the FVTX detector2) in the PHENIX experiment to signiﬁcantly reduce development time and cost.
FVTX is controlled by slow control commands from the
VME modules, Front-End Module (FEM), and FEM
Interface Board (FEM-IB), and data from the detector
was initially processed by FEM and recorded by Data
Collecting Module-II (DCM-II) and other equipment(Fig. 1).
The original slow control
and readout system(same as PHENIX FVTX)

FPGA

Slow
ControlData

from/to
INTT ladders

FEM
Interface
Board

LAN Cable

VME bus
FPGA

Front
End
ModuleThe new slow control
and readout system(Felix system)

FPGA

from/to
INTT ladders

Optical Fiber DCM-II

LAN Cable

Slow
Control
Data

PC

Felix

FPGA boardPC

was hired and optimized for each detector. INTT has
almost completed the migration to the new system with
Felix (Fig. 1), although the initial plan was to assume
control of the FEM/FEN-IB system from FVTX.
To evaluate the performance of the Felix system,measurements of pulses generated by the ROC, referred
to as calibration, were performed. The chips received
pulses with various amplitude and performed analog-todigital conversion. Further, caliblation provides the correlation between analog amplitude and digitized value.
Another crucial performance evaluated from calibration is the number of the chip responses, which canbe predicted, as the readout system must receive signals from the chip under many restrictions such as timing. Figure 2 shows the channel distribution of a readout chip, comprising 128 channels, from the calibration performed with the FEM/FEM-IB or Felix systems. Both measurements yielded consistent results.
The slight diﬀerences are owing to ﬂuctuations aroundthe thresholds. Calibration with the Felix system wascontinuously performed to conﬁrm good stability. The
diﬀerence in the number of data from the expectation
was no more than 0.1% provided as the data in the lowamplitude noisy region were excluded. The INTT operation with Felix was conﬁrmed stable and consistent
with the FEM/FEM-IB system.

Event Buffer,
Data Compressor,…, to Computing Center

Channel Distribution

350
300
Entries

As part of the transition from PHENIX to sPHENIX,
all tracking detectors including INTT adopted a
streaming readout (data readout without triggering).
The streaming readout can collect two to three ordersof magnitude more data than calorimeter triggers andeliminate trigger bias.1) To enable streaming readout,
the Felix board3) used in ATLAS experiment at CERN
∗2
∗3
∗4
∗5
∗6
∗7
∗8
∗9

FELIX

400

Fig. 1. Schema of the INTT operating system using the
FEM/FEM-IB (top) or the Felix board (bottom).

∗1

FEM

450

RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteDepartment of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory

250
200
150
100
50
0
0

20

40

60

Channel

80

100

120

Fig. 2. Comparison of the channel distribution of a readout
chip using the FEM (black) or the Felix (red) system.

References
1) sPHENIX collaboration, sPHENX Beam Use Proposal(2020).
2) C. Aidala et al., Nucl. Instrum. Methods Phys. Res. A
755, 44 (2014).
3) J. Anderson, et al. (ATLAS Collaboration), J. Phys.
Conf. Ser. 664, 082050 (2015).

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Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Development of a control application for sPHENIX-INTT detector
operation
H. Imai,∗1,∗3 Y. Akiba,∗1 J. Bertaux,∗2 K. Fujiki,∗1,∗3 M. Fujiiwara,∗4 T. Hachiya,∗1,∗4 S. Hasegawa,∗1,∗5
M. Hata,∗4 M. Kano,∗4 T. Kato,∗1,∗3 T. Kondo,∗6 C. Kuo,∗7 R.-S. Lu,∗8 I. Nakagawa,∗1 Y. Namimoto,∗1,∗4
R. Nouicer,∗9 G. Nukazuka,∗1 C. Shih,∗7 M. Shimomura,∗4 R. Shishikura,∗1,∗3 M. Stojanovic,∗2 Y. Sugiyama,∗4
R. Takahama,∗1,∗4 W.-C. Tang,∗7 H. Tsujibata,∗4 M. Watanabe,∗4 and X. Wei∗2
The sPHENIX experiment will begin at Brookhaven
National Laboratory (BNL) in 2023 to study quarkgluon plasma (QGP) using Relativistic Heavy Ion Collider (RHIC). We have developed a tracking detector
which is named INTT for several years and the barrel
assembly was completed by the end of 2022.1)
The INTT barrel consists of 56 silicon ladders. The
analog signal from the silicon sensor is ampliﬁed, digitized, and transmitted downstream in an integrated circuit chip (FPHX) mounted right next to the silicon sensors. There are as many as 2912 FPHX implemented
in the entire INTT barrel, and each can be customized
operation parameter such as gain, threshold, etc. Developing a software application to centralize the control
of FPHX chips all at once is mandatory. The application
is called “expert GUI.”The development of the expert GUI can be divided
into the following three categories.
1) Graphic User Interface (GUI) is designed to be intuitive for a user and interactively allows operation; 2)setting up a database to store the latest operation parameters for the FPHX chips; 3) establishing the communication between the server (Felix)2) which collects datafrom the FPHX chips and the client PC using Remote
Procedure Call (RPC) protocol.
The front-end code is written in Python3, especiallyusing Tkinter as a toolkit for developing GUI. Figure 1
shows the main control panels of the expert GUI. The
left panel displays the cross-section layout of the INTT
barrel, and the right represents the layout of Read Out
Cards (ROC). The ROC relays data from FPHX to thedownstream server (Felix). The trapezoid objects areclickable and will launch a new pop-up window withﬁelds where the user can type in a desired value of aparameter for a given FPHX chips. The color of objects
shows the LV power status of ROC and ladders.
As the database engine, PostgreSQL3) is used. It is
operated on a dedicated server. We introduced four categorized tables to be stored in the database. They are1) operation parameters for FPHX chips, 2) status ofchannel masks, 3) ladders and ROCs, and 4) ROCs and
∗1
∗2
∗3
∗4
∗5
∗6

∗7
∗8
∗9

RIKEN Nishina Center
Department of Physics and Astronomy, Purdue University
Department of Physics, Rikkyo University
Department of Mathematical and Physical Sciences, Nara
Women’s University
Japan Atomic Energy Agency
Tokyo Metropolitan Industrial Technology Research InstituteDepartment of Physics, National Central University
Department of Physics, National Taiwan University
Physics Department, Brookhaven National Laboratory

Fig. 1. The main control panel of the expert GUI.

Felix servers.
Our choice of the RPC framework is gRPC4) as thecommunication protocol between the Felix server and theclient PC where the GUI runs. The infrastructure of thecommunication can be established by setting up a gRPCserver on the server end and registering all functions to
be executed on the server. Once it is established, theuser can send a request for a function to be executed on
the server from the client’s PC.
The initial communication test was carried out bysending a function from the GUI to the Felix server using established RPC and checking the resulting response
from the server. The function executed was “establish
the optical communication between the ROC and theFelix.” Then the GUI received the response from theserver, which tells “the requested communication was established successfully,” as shown in Fig. 2. Developmentof the expert GUI is ongoing.

Fig. 2. Result of the attempt to establish communication using gRPC. Neither ROC#1 nor ladder#4 are physicallynot connected.

References
1) I. Nakagawa et al., in this report.
2) G.Nukazuka et al., in this report.
3) https://www.postgresql.org/ .
4) https://grpc.io/ .

- 116 -

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Forward calorimeter upgrade project in ALICE†
T. Chujo,∗1 Y. Goto,∗2 M. Inaba,∗3 and M. H. Kim∗2 for the ALICE-FoCal Collaboration
A new forward high-resolution calorimeter, called
FoCal (Forward Calorimeter) is being planned as oneof the upgrade projects for the ALICE experiment at
CERN. FoCal will be installed during LS3 (2026–2028)
for physics data taking in LHC Run-4 (2029–2032). The
letter of Intent for FoCal1) has been submitted to the
LHCC, and the FoCal project has been endorsed forthe ﬁnal R&D process for the Technical Design Report(TDR).
FoCal is a highly granular silicon-tungsten electromagnetic calorimeter combined with a conventional sampling hadronic calorimeter covering pseudorapidities of 3.2 < η < 5.8. It provides to the LHC theunique capabilities to probe small-x gluon distributions
via prompt photon production. FoCal signiﬁcantly
enhances the scope of existing ALICE physics programs by providing measurements of inclusive production cross-sections and correlations of neutral mesons,prompt photons, and jets at high rapidities, to explore
the unknown dynamics of quarks and gluons inside a
nucleus at small momentum fraction, x = 10−6 for theﬁrst time. It is also expected to elucidate the existenceof the color glass condensate (CGC),2,3) which describes
the dynamics of very densely populated gluon states atvery small momentum fractions x in the nucleus and is
expected to be important for the early stage formationof quark-gluon plasma in heavy-ion collisions.
FoCal will be located outside the ALICE solenoid
magnet, at a distance of 7 m from the ALICE interaction point. The FoCal electromagnetic calorimeter (FoCal-E) is a compact silicon-tungsten sampling
electromagnetic calorimeter with longitudinal segmentation. The current design comprises 18 layers of tungsten and silicon pads (FoCal-E PAD) with a granularity of 1 cm2 and two layers of tungsten and silicon pixels (FoCal-E PIXEL) with a high granularity(30 × 30 µm2 ). The pad layers provide measurementsof the shower energy and proﬁle, while the pixel layers enable two-photon separation down to a few mm,
to discriminate between isolated photons and merged
showers of decay photon pairs from neutral pions. The
total silicon sensor area for FoCal-E is approximately
12 m2 with approximately 150 thousand individual pad
channels and approximately 8 thouasnd pixel sensors.
The FoCal hadron calorimeter (FoCal-H) is a Cuscintillating ﬁber spaghetti calorimeter with a highgranularity of approximately 2 × 2 cm2 , which provides good hadronic energy resolution and compensa†
∗1
∗2
∗3

Condensed from the article in EP Newsletter, CERN, March
14, 2022
Faculty of Pure and Applied Sciences, University of Tsukuba
RIKEN Nishina Center
Faculty of Industrial Technology, Tsukuba University ofTechnology

tion. FoCal-H contributes to the measurement of photon isolation energy, to improve the selection of prompt
photons, and to jet measurements.
In 2022, prototypes of three FoCal subsystems,
namely FoCal-E PAD, PIXEL, and FoCal-H, were built
and tested at the PS and SPS beam lines (Fig. 1).
We (Tsukuba/RIKEN/Grenoble LPSC groups) constructed 18 layers of FoCal-E PAD prototype based on
p-type silicon sensors with 320 µm thickness, 8 × 9 padsegmentation with 1 cm2 pad size, and tungsten plates.
HGCROC4) readout ASICs were used for the PAD detector and successfully read out thorough data aggregation, a common readout unit (CRU), and a ﬁrst levelprocessor (FLP) together with other subsystems for theﬁrst time. The test beam data analysis is ongoing.5)
We also performed an irradiation test with neutrons byusing the RIKEN accelerator-driven compact neutron
source (RANS). We irradiated monitor silicon sensors(p-substrate and n-substrate) and measured IV characteristics. The total neutron dose at RANS at this timereached up to 1014 NEQ (1 MeV neutron equivalent ﬂuence). The performance evaluation of irradiated sensors
is also ongoing. Based on test results, TDR will be prepared for the ﬁnal review of the detector construction
and integration into ALICE in 2023.

Fig. 1. FoCal prototype at CERN SPS test beam line in theexperimental hall H2 (Nov., 2022).

References
1) Letter of Intent, A Forward Calorimeter (FoCal) in
the ALICE experiment (ALICE Collaboration), CERNLHCC-2020-009.
2) L. D. McLerran et al., Phys. Rev. D 49, 3352 (1994).
3) F. Gelis, Int. J. Mod. Phys. A 28, 133000 (2013).
4) The Phase-2 Upgrade of the CMS Endcap Calorimeter (CMS Collaboration), CERN-LHCC-2017-023; CMSTDR-019.
5) M. H. Kim, in this report.

- 117 -

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Beam test data analysis of the ALICE FoCal-E pad prototype
M. H. Kim∗1 for the ALICE FoCal-E detector Collaboration∗1

RIKEN Nishina Center- 118 -〉

Therefore, events where at least one cell has non-zero
TOT value in the eighth layer were selected to enhancethe electron event. Mean of TOT sum, ⟨TOT sum⟩,was calculated for all pad layers to estimate the detector performance from the longitudinal shower proﬁle.
Figure 1 shows the longitudinal shower proﬁles of the
FoCal-E pad prototype with four diﬀerent beam energies. As the beam energy increases, not only does the⟨TOT sum⟩ increase but also the shower max layers
move backward.

〈

The ALICE FoCal-E detector1) is an electromagnetic sampling calorimeter with a total depth of 20 radiation length (X0 ), which aims to measure the direct
photons produced by quark-gluon Compton scattering
to explore the small-x parton structure of nucleons andnuclei. It is composed of 18 low-granularity silicon padlayers, with a cell size of 1 × 1 cm2 for energy measurement, and 2 high-granularity silicon pixel layers, witha cell size of 30×30 µm2 for position measurement andphoton shower separation because the direct photons
should be distinguished from those decayed from π 0 .
All layers have the tungsten sheets with a thickness of
1 X0 followed by silicon layers.
FoCal-E has been developed since 2016 to be used forphysics data collection in 2029. Now, we are studying
the detector performance to write a technical design
report and optimize the ﬁnal design. A FoCal-E prototype with a transverse dimension of 9 × 8 cm2 was
prepared and tested using high-energy electron beams
from 20 to 350 GeV at CERN-SPS in September andNovember 2022. In this article, we report the status
and plan of the pad data analysis.
FoCal-E pad will use the HGCROC chip, which is
being developed by the CMS experiment for a highgranularity calorimeter.2) It provides ADC for signals
up to 100 Minimum Ionizing Particles (MIP), which isused for energy calibration of each pad and time-overthreshold (TOT), which is ﬁred from 100 MIP for large
signals to measure photon energy up to 2 TeV. TOT
is a technique that obtains the energy by measuring
the pulse width of the digital output. Although it allows us to measure large signals, nonlinearity between
the TOT and energy and the reliability of energy measurement in the intermediate dynamic range where it
is converted from ADC to TOT need to be carefully
studied.
A pad layer of the prototype consists of 72 cells.
When the TOT values of all cells in the eighth layer,
which is one of the shower maximum layers, weresummed up for a 150-GeV beam energy, two peaks
were observed. One was the case when all TOT values
were zero. The other was a Gaussian peak around a
non-zero value.
In the electron beam, a ﬁnite fraction of the hadronbackground exists. We assumed the former comes fromthe hadron background and the latter comes from theelectron. This assumption is reasonable because themaximum energy deposit of a cell in the eighth layer
by the electron was predicted by simulation to be larger
than a level of 200 MIP, which is suﬃcient to ﬁre the
TOT even though the electron hits the edge of a cell.

Fig. 1. Longitudinal shower proﬁles of the FoCal-E pad
prototype, which shows the ⟨TOT sum⟩ with four different beam energies over the layers. Layer 5 and 10 are
the pixel layers. Layer 18 is not shown due to a gain
problem.

The FoCal-E pad prototype showed a reasonable
performance even though the analysis cut condition
was simple. However, the estimated energy resolution
was 1.5 times worse than that expected by simulation.
We are now processing the quality assurance (QA) for
each run. After QA, more strict conditions will beapplied to separate the electron from the hadron background. Calibration parameters will also be provided
to combine the TOT and ADC and also to reduce the
TOT nonlinearity. Taking these factors into account,precise detector performances will be studied.
References
1) ALICE Collaboration, CERN-LHCC-2020-009 (2020).
2) CMS Collaboration, CERN-LHCC-2017-023 (2017).

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Activation measurement of copper by 238 U irradiation
A. Akashio,∗1 K. Tanaka,∗1 N. Shigyo,∗1,∗2 and K. Sugihara∗1,∗2,∗3
γ-ray residual radiation dose around the copper
beam dump of BigRIPS, where the highest radiationdose rate is expected at RIBF, is occasionally estimated by Monte-Carlo radiation transport code suchas PHITS.1) However, there are no measured data forthe activation caused by uranium beam and the accuracy of the calculation remains unknown. Therefore,
345 MeV/nucleon uranium beams were irradiated ona stack of copper sheets, which is the material of thebeam dump, to measure the produced radioisotopes
and compare them with the PHITS calculation.1)
Ten 1 mm thick copper sheets were stacked. A
10 mm thick copper plate was applied as the radiation sample. After the irradiation of the uranium
beam, γ rays were measured with a germanium detector to identify the nuclide and quantity of the produced radioisotopes. To consider long-lived radiationfrom the beam dump, the γ rays were measured ninemonths after the irradiation. Figure 1 shows the depth
dependence of the observed radioactive nuclei. The
depth was reduced from the copper sheet number. The
amount of the radioisotopes was evaluated from theindividual measurements of the copper sheets. The
range of 345 MeV/nucleon uranium-238 beam in copper was approximately 3.3 mm. Manganese-54, cobalt56, -57, -58, and cobalt-60 were observed at all the copper sheets. Therefore, the isotopes of manganese andcobalt in the range 1–3 mm were produced through areaction between the uranium and copper nuclei. The
isotopes deeper than 4 mm were produced by a nuclear reaction of secondary neutrons with copper nuclei. Further, the secondary neutron was produced

from the reaction with uranium beam and copper.
Consequently, osmium-185, hafnium-175, zirconium97, and ruthenium-103 were observed in the depth
range of 4–6 mm. As nuclei of mass number of approximately 180 are heavier than typical ﬁssion fragments of uranium which mass are approximately 140,
osmium and hafnium are supposed to be produced byprojectile fragmentation of uranium beam. Zirconium
and ruthenium, with approximate mass number of 100,
are typical nuclides from in-ﬂight ﬁssion of uranium
beam. The range of produced nuclei in copper was
longer than the 3.3 mm range of uranium beam because their atomic number are smaller than that of uranium. Moreover, the nuclei produced by ﬁssion were
not observed at 7 mm depth and beyond.
The measured activity of nuclei was compared withthe calculation by PHITS. Figure 2 shows the activity
ratio of the calculated to measured value.

Fig. 2. Ratio of nuclei calculated evaluation by PHITS tomeasured values.

Fig. 1. Depth dependence of the observed radioactive nuclei in the copper sheets. The depth was converted fromthe number of the sheets.
∗1
∗2
∗3

RIKEN Nishina Center
Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University
High Energy Accelerator Research Organization (KEK)- 119 -

The calculated activation rate of copper by the secondary neutron was approximately 50% of measured
value. The calculated production rate of projectilefragmentation nuclides of osmium-185 and hafnium175 were several times higher than measured values.
However, the ratios of the ﬁssion nuclei zirconium-97,
and rutheniu-103 were approximately identical to themeasured values.
Consequently, the benchmark of activation for
345 MeV/nucleon uranium-beam irradiation on copper material was obtained. The PHITS evaluation wasconsistent the measured values within a factor of several.
Reference
1) T. Sato et al., J. Nucl. Sci. Tech. 55, 684 (2018).

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Wi-Fi service in the RIBF experimental area
H. Baba,∗1 H. Honda,∗2 and M. Kurokawa∗2

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Internet service is one of the essential infrastructures
for research activities. For information security, networks are required to be separated depending on users
and purposes. In the RIBF, an easy-to-use and secure network environment is necessary because many
external researchers participate in experiments one after another. For example, a dedicated network has
been constructed in the RIBF experimental area fordata acquisition during experiments using the BigRIPS
beam line. However, access to the Internet is accessed
through RIKEN’s intranetwork, and there are concerns
about network separation for external researchers.
To achieve secure network separation, Eduroam andguest Wi-Fi services provided by RIKEN Information
System Divisions for external researchers were introduced in the B1F and B3F measurement rooms of the
RIBF experimental area. The B1F and B3F measurement rooms (each ﬂoor has an area of approximately
2000 m2 ) are located apart from each other, and somerooms are separated by walls. This required the installation of a large number of wireless access points toprovide wireless signals to the entire area. By adopting
leaky coaxial (LCX) cables1,2) as wireless antennas, wehave successfully established a cost-eﬃcient and easyto-maintain Wi-Fi environment.
An LCX cable is a type of antenna in which slots
are placed in the outer conductor of a coaxial cable
to enable wireless communication. Figure 1 shows the
structure of an LCX cable. We adopted LCX cables(Proterial Ltd. F-8D-LCX) that can be extended toa maximum cable length of 100 m and are compatible
with the 2.4 and 5 GHz Wi-Fi bands. A diagram of thewiring in the B1F and B3F measurement rooms of the
RIBF building is shown in Fig. 2. Boxes labeled withAP, circles, and bold lines are the access point, experimental room, and LCX cables, respectively. An HPE
Aruba AP-504 access point, which is compliant withthe 2.4 and 5 GHz Wi-Fi bands, was adopted. Two
LCX cables are connected to each access point, and

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Fig. 2. Wiring diagram for the B1F and B3F measurement
rooms in the RIBF building.

two access points were installed on each ﬂoor. Eight
LCX cables (15, 38, 40, 50, 50, 60, 67, and 80 m)
were used, and the total length was 400 m. Cables
were routed along walls or cable racks on the ceiling.
As shown in Fig. 2, four access points and eight LCX
cables were suﬃcient to cover all the B1F and B3F
measurement rooms.
The Wi-Fi signal strength is generally consideredgood if it is above −50 dBm. Near the access point, the
Wi-Fi signal strength was approximately −40 dBm forboth the 2.4 and 5 GHz bands. At a distance of 80 mfrom the access point, the signal strength was about−70 dBm for the 2.4 GHz band and less than −90 dBm
for the 5 GHz band. However network communication
was possible with the 2.4 GHz Wi-Fi band.
These results show that the Wi-Fi environment using LCX cables is eﬀective in an experimental areasuch as the RIBF, where several measurement rooms
are separately located. In the future, we plan to construct a Wi-Fi environment with LCX cables in themeasurement rooms of the Nishina Building.
References

Insulator

1) https://ww.hcnet.co.jp/products/wireless/lcx/lcx.
html .
2) T. Igarashi et al., in Computers in Railways IX, edited
by J. Allan et al., (WIT Press, 2004), p. 455.

Slot

Fig. 1. Structure of an LCX cable.
∗1∗2

RIKEN Nishina Center
RIKEN Information Systems Division- 120 -

Ⅱ-9. Instrumentation
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Computing and network environment at the RIKEN Nishina Center
T. Ichihara,∗1 Y. Watanabe,∗1 and H. Baba∗1
We operate the Linux cluster systems1) at the
RIKEN Nishina Center (RNC).
Figure 1 shows the current conﬁguration of theLinux servers at the RNC. Scientiﬁc Linux (SL) 7 andCentOS Stream 8 have been installed in these systems.

end in July 2023, we are preparing for a new mail system without using Sophos PMX. Figure 2 shows theemail trends in 2022. Approximately 59% of the incoming emails were blocked by the PMX ip-blocker,
and the number of the blocked emails (mostly spams)
was increasing monthly.













 



























  
Fig. 2. Mail trends: message categories in 2022.




 



    











  


















Fig. 1. Conﬁguration of the RIBF Linux cluster.

Among these servers, the hardware of RIBFSMTP1,
RIBFSMTP2, INDICO2, RIBFSS, and RIBFUSER
are HP ProLiant DL320e. Because the hardware support of the HP DL320e was ending in December 2022,
we replaced the hardware of the RIBFSMTP1 with the
newly installed HP DL160 in November.
HP ProLiant servers were repaired for 8 times. They
were faults of two batteries and one capacitor for cachememories, and ﬁve hard disk drive units.
The hosts RIBFSMTP1/2 are the mail gateways
used for tagging spam emails and isolating virusinfected emails. The latest version of Sophos EmailProtection-Advanced (PMX 6.4.9) was installed. However, as the support for Sophos PMX is scheduled to∗1

RIKEN Nishina Center- 121 -We tested Clam AV,2) a free anti-virus software, on
the test server RIBFSMTP4 and found it working well.
This could be one possibility for virus protection ofemails when we drop Sophos PMX in 2023. We havealso tested Rocky Linux 8 on RIBFTEST as a new
operating system and the installation possibility of indico,3) which is not supported in RHEL8.
An anonymous ftp server, FTP.RIKEN.JP, is managed and operated at the RNC. Major Linux distributions are mirrored daily for the convenience of theusers. A memory leak was observed, and a workaroundis in progress. It was announced in December 2022 that
the CERN and Fermilab jointly plan to provide AlmaLinux as the standard distribution for experiments at
our facilities, reﬂecting recent experience and discussions with experiments.4) Therefore, our new servers
may soon adopt AlmaLinux as an operating system.
We have been operating approximately 70 units ofwireless LAN access points in RNC for the convenienceof experiments and daily work. Two old and degraded
access points, WAPS-APG600H, were replaced by newaccess points, WAPM-1266R.
References
1) T. Ichihara et al., RIKEN Accel. Prog. Rep. 55, 102(2022).
2) https://www.clamav.net/ .
3) https://getindico.io/ .
4) https://linux.web.cern.ch/ .

Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

CCJ operations in 2022
S. Yokkaichi,∗1 Y. Akiba,∗1 T. Ichihara,∗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) experimentbeing conducted at RHIC. Since then, CCJ has been
providing numerous services as a regional computing
center in Asia. We have transferred several hundred
terabytes of raw data ﬁles and nDSTa) ﬁles from theUSA.
Many analysis and simulation projects are being conducted at CCJ, which are listed on the web page
http://ccjsun.riken.jp/ccj/proposals/. As of December 2022, CCJ has contributed to 47 published papers
and 45 doctoral theses.

queuing system, LSF 9.1.3.6) Table 2 lists the numberof malfunctioning SATA or SAS disks in the HP servers,
namely, computing nodes and NFS/AFS servers. The
OS of nine calculation nodes and of two interactive
servers operated in SL7.97) and the rest are still old.
Two old interactive servers will be shutdown following
the upgrade of the computing nodes.
Table 2. Number of malfunctioning HDDs in HP servers
during 2011–2022.
Type (TB) total
SATA (1.0)
192
SATA (2.0)
120
SATA (4.0)
26
SATA (6.0)
20
SAS (0.15)
38
SAS (0.3)
26

Computing hardware and software
The network conﬁguration and computing hardware(nodes) and software (OS, batch queuing systems,
database engine, etc.) are nearly the same as describedin the previous APR,3) and the number of servers are
summarized in Table 1. The main server (users’ home
directory, NIS, DNS, and NTP), SAS RAID for theserver (15.5 TB), and one login server were replaced,
and a new interactive server was deployed in Oct. 2022.
Interactive servers are used for the compilation and test
runs for the jobs before the submission to the computing nodes. Two spare machines for interactive and login
servers were prepared.
Table 1. Number of servers and disk sizes, as of 2022 Dec.
Dagger(†) shows replacement and newly deploying inthis year (detail is in the text).

main server

num
ber
1

login serverinteractive server

2
4disk size(TB/node)
6(built-in)+ 15.5(RAID)-

calculation node 1
calculation node 2
work disk server
DB server
library(AFS) servertransfer server
docker test server

16
8
2
1
1
2
1

10
20
26 / 391
9
12 / 39-

type
DL360G10†
DL20G9/DL20G10†-/DL320G6/
DL160G9/DL20G10†
DL180G6
DL180G6
DL180G9/DL385G10
DL145G3
DL180G6
DL180G9/DL380G10
DL20G9a)

RIKEN Nishina Centerterm for a type of summary data ﬁles in PHENIX

12
20
5
1
0

13
16
2
0
0

14
11
0
2
1

15
14
10
3
1

16
8
2
5
0

17
18
10
1
1

18
16
2
0
0
3
0

19
8
10
0
0
6
2

20
9
5
0
0
3
1

21
10
9
2
0
5
2

Three 10-KVA UPSs are operated as power supplies
for these CCJ nodes. The next replacement is plannedin Mar. 2026 considering the 5-year battery life. Rearrangement of AC power lines for the nodes from these
UPSs was performed for the re-balancing of load, immediately after the deployment of new servers, during
the planned power outage in Wako Campus.
The replacement of the main switch is planned in
2023, to support the 10 GBASE-T network for servers,
while 10 GBASE-LR and SR are used now only for the
uplink to RIKEN-LAN and for the downlink to edge
switches for the calculation nodes, respectively.
Joint operation with ACCC/HOKUSAI
CCJ and the RIKEN IT division have been jointly
operated since July 2009. In April 2015, “HOKUSAI
Greatwave”8) system was launched and the joint operation with CCJ continued, with the inclusion of a
new hierarchical archive system wherein approximately
1070 TB of CCJ data were stored as of December 2022.
A breakdown of the data is presented in Table 3.
Table 3. Tape usage in Hokusai as of December 2022.

In addition, we operate one dedicated server for the
RHICf group4) and two servers for the J-PARC E16
group5) in order to maintain their dedicated compilation and library environments along with some data.
We operate 26 computing nodes, and 352 (= 8 ×
17 nodes + 24 × 9 nodes) jobs can be processed simultaneously via these computing nodes using a batch
∗1

11
9
4
1
1

user

total

size (TB)

1068

PHENIXoﬃcial749

KEK/
J-PARC
173

RHICf
8

user-levelarchive
137

References
1) http://ccjsun.riken.jp/ccj/ .
2) http://www.phenix.bnl.gov/ .
3) S. Yokkaichi et al., RIKEN Accel. Prog. Rep. 55, 103(2022).
4) Y. Itow et al., arXiv:1409.4860.
5) S. Yokkaichi, in this report.
6) https://www.ibm.com/docs/en/spectrum-lsf/ .
7) http://www.scientificlinux.org/ .
8) https://i.riken.jp/supercom/ .

- 122 -

22
5
7
0
0
2
1

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. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Control of electrical conductivity in diamondby boron-implantation using an ECR ion source
H. Yamazaki,∗1 T. Minamidate,∗2 M. Kidera,∗1 A. Yamamoto,∗3 R. Kato,∗4 and H. Ueno∗1
Diamond is an excellent electrical insulator with alarge band gap of 5.5 eV. It becomes a semiconductor when doped with a small amount of boron (forp-type) or phosphorus (for n-type). When doped beyond the metal-to-insulator transition at a boron density of nB ∼ 3 × 1020 B/cm3 , boron-doped diamondexhibits superconductivity in the samples grown by thehigh-pressure and high-temperature synthesis.1) Theoretically, the superconducting critical temperature Tc
can be signiﬁcantly increased by reducing the eﬀects
of disorder in boron-doping processes.2) For a higher
Tc , more subtle control of doping using CVD and/or
MBE methods is highly required. However, a diﬀerent method based on ion implantation is also worth
investigating as it enables selective ion doping in a controlled manner. This has great potential for future device applications. Successful inclusion of boron ions by
the implantation technique has been conﬁrmed using
SEM/EDS measurements. The surface image of oursample and its EDS spectrum are shown in Fig. 1. At
0.19 keV, we can see an energy peak from the boron
ions embedded in the diamond.

Fig. 1. Left: SEM image of our sample with a boron concentration of nB ∼ 6.8 × 1022 B/cm3 ; right: EDS spectrum obtained with an acceleration voltage of 7.0 kV.
The strongest peak comes from the carbon atoms in the
diamond.

For the past few years, we have been trying to control
the electrical conductivity in Ib-type diamonds usingboron-ion implantation. To reduce the lattice damage
produced during the implantation, we performed annealing treatments after implantation. As the phase
diagram of carbon shows, the diamond is not stable
at low pressures; therefore, we annealed the samples
at 800◦ C and 4 GPa for 1 hour. Contrary to our expectations, the annealed samples exhibited no sign ofsuperconductivity. The laser Raman spectra (632.8 nm
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Faculty of Science, Tokyo University of Science
Graduate School of Engineering and Science, Shibaura Institute of Technology
Condensed Molecular Materials Laboratory, RIKEN

excitation) indicated that the annealing promoted theformation of NV− centers, which behave as carrier traps
in the diamond.
In this ﬁscal year, to decrease the NV− defect density, we used single-crystals of IIa-type diamond witha nitrogen concentration of less than 8 ppm (Fig. 2,
right). We also investigated the dependence of boronimplantation yield on the crystallographic orientationof diamond surface: (100) and (111). Using an ECR
ion source,3) boron ions were implanted into the diamond crystals at 5 keV corresponding to an implantation depth of ∼10 nm. Five samples of diﬀerent concentrations from nB ∼ 5 × 1020 to 2 × 1022 B/cm3 wereprepared. These samples were annealed under the same
conditions as noted above.

Fig. 2. Pristine single-crystals of IIa-type diamond (right)
and Ib-type diamond (left, for comparison). The size ofeach crystal is approximately 1 × 1 × 0.3 mm3 .

Figure 3 shows a sample and some parts of highpressure media after removing the sample. For comparison, the implanted samples without annealing werealso prepared. We are now ready to measure the samples with diﬀerent combinations of the conditions: (a)ﬁve diﬀerent nB ’s, (b) two types of surface orientations:(100) and (111), and (c) with/without annealing treatment after implantation.

Fig. 3. The boron-implanted diamond (arrowhead) after theprocess of high-temperature and high-pressure annealing. Parts of high-pressure media are also shown.

References
1) E. A. Ekimov et al., Nature 428, 542 (2004).
2) T. Shirakawa et al., J. Phys. Soc. Jpn. 76, 014711 (2007).
3) M. Kidera et al., Eur. J. Mass Spectrom. 13, 239 (2007).

- 123 -

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Lattice sites of 23 Ne implanted in single-crystal ZnO studied by
β-NMR/NQR spectroscopy
H. Yamazaki,∗1 H. Nishibata,∗2 A. Gladkov,∗1 T. Kawaguchi,∗3 H. Ueno,∗1 Y. Ichikawa,∗2 A. Takamine,∗1
T. Sato,∗1 K. Kawata,∗1,∗4 W. Kobayashi,∗3 M. Sanjo,∗3 L. C. Tao,∗5 Y. Nakamura,∗3 T. Asakawa,∗3 Y. Sasaki,∗3
K. Totsuka,∗3 K. Doi,∗3 T. Yada,∗3 K. Asahi,∗1 Y. Ishibashi,∗6 K. Imamura,∗1 T. Fujita,∗7 G. Georgiev,∗8 and
J. M. Daugas∗9
Zinc oxide is a II-VI binary compound that crystalizes in a hexagonal wurtzite structure. The compoundhas received signiﬁcant attention because of its potential
for application in optoelectronic devices and transparent conducting ﬁlms as well as in space environments
owing to its radiation hardness. In particular, owing towide and direct band gap of 3.4 eV at room temperature,
ZnO can be utilized in next-generation devices for shortwavelength optoelectronics such as light-emitting diodes
operating in the spectral range from blue to ultraviolet.
For utilizing ZnO as semiconductors, both n-type and ptype doped ZnO are necessary. We can fabricate n-type
ZnO through the partial substitution of Zn with Al, Ga,
or In, whereas fabricating a reliable high-quality p-type
ZnO still remains a challenge. Despite considerable research conducted so far, high-quality p-type ZnO has notbeen fabricated.
Recently, ﬁrst-principles calculations performed by
Malyi et al. indicated that a noble gas (He, Ne, or Ar)
implanted in ZnO can serve as a new type of dopant.1)
In spite of its fully occupied atomic orbitals, the noble
gas strongly changes the surrounding electronic statesby pushing away the electrons around it. This suggeststhat a noble gas can be a functional dopant in ZnO, andthe investigation of ZnO using noble-gas nuclei as local
probes is much anticipated. In this study, we investigate,in particular, Ne implantation into single-crystal ZnO.
For details of the experimental setup, see our earlier
report.2) First, using the β-NMR method, we determined
the nuclear g-factor for the radioactive 23 Ne isotope (nuclear spin I = 5/2) that decays through β-emission into
the nucleus 23 Na with a half-life of T1/2 = 37 s. Thereafter, we implanted the 23 Ne isotopes as probe nuclei
in ZnO and measured the electric ﬁeld gradient (EFG)at the 23 Ne stopping sites using β-NQR method. EFGs
are highly sensitive to the electronic density in the vicinity of the relevant nucleus. This sensitivity can be used
to identify the crystallographic sites for the implanted
23
Ne and to study the eﬀect of 23 Ne implantation on
the charge distribution around the nucleus. The β-NQR
spectrum obtained at 47 K is depicted in Fig. 1.
We determined the electric ﬁeld gradient Vzz at the
∗1
∗2
∗3
∗4
∗5

∗6
∗7
∗8
∗9

RIKEN Nishina Center
Department of Physics, Kyushu University
Department of Physics, Hosei University
Center for Nuclear Study, University of Tokyo
School of Physics, Peking University
Cyclotron and Radioisotope Center, Tohoku University
Department of Physics, Osaka University
CSNSM, CNRS/IN2P3, Université Paris-Sud
CEA/DAM-Ile de France

Fig. 1. β-NQR spectrum of 23 Ne implanted in ZnO single
crystal. The dashed line represents the least χ-square
ﬁtting result to a Gaussian function.

position of 23 Ne in ZnO. The value of (3.1 ± 0.3) ×1020 [V/m2 ] for 23 Ne compare well with that for 20 Naon the interstitial site (see Table 1). Although Ne occupies an octahedral interstitial site (the lowest energysite for Ne),1) Na in the form of ion (Na+ ) is shifted by
0.23 Å from the ideal octahedral site parallel to the caxis.6) Considering that both Ne and Na+ have the same
electron conﬁguration 1s2 2s2 2p6 , we must study the position dependence of Vzz further in detail theoretically.
Table 1. Experimental results of the electric ﬁeld gradientVzz in ZnO for the β-NQR probes of 8 Li, 12 N, and 20 Na.

Implanted
probe
Vzz[1020 V/m2]
Lattice site

8

Li 3)

1.342±0.001
interstitial site
close tooctahedral site
0.6029±0.0004
Zn
substitutional
site

12

N 4)

0.86
±0.11
site
unclear

20

Na 5)

2.7
interstitialsite close tooctahedralsite6)
1.8
Zn
substitutionalsite6)

References
1) O. I. Malyi et al., npj Comput. Mater. 5, 38 (2019).
2) H. Nishibata et al., RIKEN Accel. Prog. Rep. 52, 56(2018).
3) J. R. Adelman et al., Phys. Rev. B 106, 035205 (2022).
4) R. Matsumiya et al., Hyperﬁne Interact. 178, 63 (2007).
5) K. Minamisono et al., Nucl. Instrum. Methods Phys. Res.
A 616, 45 (2010).
6) U. Wahl et al., Semicond. Sci. Technol. 31, 095005 (2016).

- 124 -

Ⅲ-1. Atomic & Solid State Physics (Ion)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Evaluation of horizontal irradiation for SiC vertical diodes
M. Iwata,∗1 M. Takahashi,∗1 N. Ohtani,∗1 N. Nemoto,∗1 and H. Shindou∗1
Silicon carbide (SiC) devices are the candidates fornext generation power device for space applications because of their excellent electric property. To clarify thedestruction mechanism of SiC devices caused by heavyions, which is a critical issue for usage in harsh radiation environments, we have conducted experiments under various irradiation conditions.
The test was conducted on the 650 V commercial SiC
vertical diodes with a junction barrier Schottky (JBS)
structure, which is the same as in the previous report.1)
Test devices were decapped and irradiated with 84 Kr
ions at room temperature in air using RIKEN AVF coupled with the RIKEN Ring Cyclotron (RRC). The energy of ion at incident edge of the device was 3040 MeV.
Irradiations were performed from diﬀerent sides: one
was from the upper side, the other was from the left side,horizontal to the device surface, as shown in Fig. 1. A
reverse voltage (VR ) was applied to the device and theleakage current (IR ) was continuously monitored during
irradiation. Further, VR was initialized at 240 V and increased in 40 V steps after the total ﬂuence at each VR
reached 1.0 × 106 ions/cm2 . The maximum VR in thistest was 640 V, which was close to the rated voltage ofthe test device.

Fig. 1. Irradiation direction to the device.

Figure 2(a) shows the transition of IR at the end of irradiation at each VR . The device irradiated from the left
side was broken at VR = 600 V, whereas that irradiatedfrom the upper side was not broken until the maximum
VR . Figure 2(b) shows the transition of IR with increasing ﬂuence at VR = 600 V irradiated from the left side;
IR abruptly increased and reached approximately 6 mA.
The same test was conducted for diﬀerent samples to
conﬁrm the eﬀects of crystal direction relative to ion
tracks. The samples were 650 V SiC diodes createdby the same company; however its structure was planartype, which does not have p+ regions at the Schottky
contact. No increase in IR was observed when irradiatedfrom both sides, which implies that interaction between
the p+ regions and charges generated by a heavy ion
aﬀected the device breakdown more than crystal direction.
∗1

Research and Development Directorate, Japan Aerospace Exploration Agency

Fig. 2. (a) Transition of IR during irradiation and (b) Transition of IR at VR = 600 V irradiated from left side.

Follwing the test, a surface damage considered evidence of single-event burnout (SEB) was observed on thedevice irradiated from the left side. It was located approximately 320–450 µm from the left edge of the device.
Focusing on linear energy transfer (LET) transition in
the device, the highest LET with a Bragg peak was
43.8 MeV/(mg/cm2 ) at 383 µm, which is approximately
the center of the damage site. Note that incidence position in device thickness direction remained unclear inthis test; however, for triggering SEB, an ion was introduced into the depletion layer because deposited charges
must be accelerated by the electric ﬁeld.
The electric ﬁeld lines within depletion layer are perpendicular to the surface under certain VR ; thus, charges
generated by an ion move vertically in vertical diodes.
These charges are ampliﬁed in the collection process,which can cause device degradation or destruction. Although less ampliﬁcation can be expected for horizontal irradiation because reduction in charge multiplication with increasing tilt angle has been reported,2) a
rapid increase in IR and surface damage were observedin the device irradiated from the left side. The same behavior could not be observed at normal incidence (i.e.,
perpendicular to the device surface) with the same ion
and device; gradual increase of IR at lower VR was observed instead. Focusing on a small vertical region in
the device, charges generated by horizontal irradiation
are considered to exist as a point, and all charges including ampliﬁed charges might be collected in an extremely
short period of time. However, the time for all charges
to be collected at normal incidence might be longer thanhorizontal irradiation because charges are generated in a
vertical line along an ion track. This diﬀerence in collecting time period might aﬀect the diﬀerence in destruction
mode.
References
1) M. Iwata et al., RIKEN Accel. Prog. Rep. 5, 106 (2022).
2) A. Javanainen et al., IEEE Trans. Nucl. Sci. 64, 2031
(2017).

- 125 -

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Improvement of the signal-to-noise ratio of Rb D1 ﬂuorescence insuperﬂuid helium using picosecond time-resolved detection
H. Endo,∗1,∗2 K. Ishii,∗3 K. Imamura,∗2 A. Takamine,∗2 Y. Matsuo,∗1,∗2 T. Tahara,∗3 and H. Ueno∗2
Our research group is developing a laser spectroscopy technique (OROCHI) for atoms in superﬂuid
helium (He II). When atoms are injected into He II,
the surrounding helium atoms are pushed out by thePauli repulsion force.1) The resulting vacuum region
is referred to as an atomic-bubble. As the shape ofthe electron orbit of the impurity atom is deformed
according to its energy state, the atomic bubble is also
deformed following the shape change of the atomic orbit. The wavelengths of the atomic transitions for boththe absorption and emission in He II are shifted fromthose in vacuum due to this deformation cycle.2) It
is estimated that the bubble deformation requires anorder of a few picoseconds;1) however, till date, therelaxation time has not been measured in the time domain in bulk He II. Because the emission wavelengthis expected to change with the degree of the bubble
deformation, we aim to determine the relaxation timeof Rb atomic bubbles in He II through time-resolved
emission measurements at diﬀerent wavelengths.3)
We have successfully observed laser-induced ﬂuorescence (LIF) from Rb atoms of the D1 line (absorption center wavelength in He II: 778.0 nm) picosecond
laser excitation and detection with time-correlated single photon counting (TCSPC).3) To measure the ﬂuorescence that is weaker at shorter wavelengths thanthe center wavelength, the signal-to-noise ratio must
be increased. Here, we report the introduction of ametal cell with anti-reﬂection (AR) coated windows
instead of a conventional quartz-cell to reduce the effect of scattered light from the excitation laser.
Figure 1 shows the experimental setup. We used apicosecond mode-locked Ti:sapphire laser (laser power:
100 mW, repetition rate: 80 MHz, pulse width:
1.6 ps, center wavelength: 778.2 nm) as the excitation
laser. LIF was detected using an avalanche photodiode (APD) through a monochromator. The transmission of AR-coated windows is greater than 99.4% in
the wavelength range of 780 nm to 830 nm. Because alarge proportion of the background photons are considered to originate from the scattered light on the surfaceof the quartz cell, the introduction of the AR-coatedwindows is expected to reduce the scattered light, inthe LIF detection eﬃciency.
Figure 2 shows the observed photon intensities as afunction of delay time. The peaks in Fig. 2 are at thetime of the excitation laser incidence, from which the
Rb atoms decay along their spontaneous emission life∗1∗2∗3

Department of Advanced Sciences, Hosei University
RIKEN Nishina Center
RIKEN Center for Advanced Photonics- 126 -

Fig. 1. Experimental setup of LIF detection.

Fig. 2. Intensity detected by TCSPC using (a) a quartz
cell, (b) AR coated windows.

time of 27 ns. Figure 2(a) shows the result of the LIF
observation using the conventional quartz cell without
AR coating. Both the LIF signal (blue) and a relatively large amount of laser-scattered light (orange)
were observed. Note that the background also contains
ambient light other than the laser in the environment
and areas with a value of 0 correspond to the timing when the detection device can not count photons.
Figure 2(b) shows that LIF increased when AR-coatedwindows were used, whereas laser scattered light wasalmost negligible. We plan to observe weaker emission
on the short wavelength side through further improvement of the signal-to-noise ratio by increasing the dataacquisition time.
References
1) B. Tabbert et al., J. Low Temp. Phys. 109, 653 (1997).
2) Y. Takahashi et al., Phys. Rev. Lett. 71, 1035 (1993).
3) Y. Takeuchi et al., RIKEN Accel. Prog. Rep. 54, 105(2020).

Ⅲ-1. Atomic & Solid State Physics (Ion)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of a spin polarized RI atomic beam apparatus the using
atomic resonance method
K. Imamura,∗1 Y. Fukuzawa,∗1,∗2 A. Takamine,∗1 S. Go,∗1 A. Gladkov,∗1 M. Tajima,∗1 and H. Ueno∗1
We are currently developing a spin-polarized radioactive isotope (RI) atomic beam apparatus using theatomic beam magnetic resonance (ABR) method to apply RIs to nuclear structure study and material sciences. The apparatus mainly consists of the following
two parts: i) An RI ion neutralizer based on a radio frequency (RF) trap and laser cooling technique for generating a low-energy RI atomic beam. ii) An ABR apparatus consisting of a sextupole magnet, dipole magnet, quadrupole magnet, and RF cavity for producing
a highly polarized RI atomic beam.1) In our method,
RI and laser-cooled ions are simultaneously trapped ina linear Paul trap at ﬁrst. Then, the energy of trapped
RI ions is sympathetically decreased by the Coulombinteraction between laser-cooled and trapped RI ions
(sympathetic cooling).2) After cooling the RI ions, an
ion neutralization gas is blown against the trapped ions.
An RI atomic beam produced by the above neutralization process is delivered to the ABR apparatus. In the
ABR apparatus, spin polarization is achieved by a combination of double spin selection using a magnetic ﬁeld
gradient generated by a sextupole and quadrupole magnet and single spin ﬂip by magnetic resonance with an
RF cavity assembled in a uniform magnetic ﬁeld generated by a dipole magnet. In the development process,establishing highly eﬃcient RI ion neutralization and
RI atomic beam transport method is crucial because
the ABR method itself is a well-established techniquein the ﬁeld of measuring nuclear electromagnetic moment of stable isotopes. In this study, we report on an
oﬄine laser cooling experiment conducted using singly
charged 88 Sr ions toward sympathetic cooling for developing the neutralizer.
Figure 1 shows (a) the schematic of the setup and(b) corresponding energy levels of the 88 Sr+ ion in theexperiment. Laser pulses from a Nd: YAG laser (wavelength: 1064 nm, repetition rate: 1 Hz, pulse duration: 5 ns, intensity: ∼2.5 mJ) were focused on a
SrTiO3 plate (width × hight × thickness = 10 × 10
× 0.5 mm3 ) using a convex lens with a mm focal lengthof 350 mm. The 88 Sr+ ions produced by laser ablation
were trapped at the center electrode (denoted as “C”
in Fig. 1) in our linear Paul trap. For ion trapping, we
introduced He as the buﬀer gas whose pressure was approximately 2.0 × 10−2 Pa for buﬀer gas cooling. After
200 s of buﬀer gas cooling, the buﬀer gas was quickly
pumped out and pressure was maintained in the rangeof 10−6 –10−7 Pa. To produce laser-cooled 88 Sr+ ions,
we prepared two lasers. One was the cooling laser with
∗1
∗2

RIKEN Nishina Center
Department of Advanced Science, Hosei University

Fig. 1. (a)The schematic of the experimental setup. (b) The
related energy levels of Sr ion in the experiment.

awavelength of 422 nm corresponding to the D1 (5S1/2 –5P1/2 ) transition of the 88 Sr+ ion. The other was therepump laser (wavelength: 1092 nm) used to pump
88 +Sr ions de-excited in the 4D3/2 metastable state
to the 5P1/2 excited state. We irradiated the trappedions with both lasers in a co-propagation conﬁguration. The optical paths of the lasers were spatially combined using a dichroic mirror (Thorlabs, DMLP650).
The laser powers of the cooling laser and the repump
laser were 1.5 mW and 5 mW, respectively. The laser
induced-ﬂuorescence (LIF) emitted from 88 Sr+ ions wascollected using a convex lens with a focal length of
100 mm and detected using a photo-multiplier tube
(Hamamatsu photonics, H16721-50). In order to reduce the background stray light, an interference ﬁlter
with a bandwidth of 435 ± 20 nm (Edmund optics, Fluorescence band-pass ﬁlter) was mounted in front of the
PMT. We obtained the LIF spectra by scanning thelaser frequency of the cooling laser. So far, we have
conﬁrmed the onset of laser cooling eﬀect by observing the narrowing of the line width and change of line
shape under diﬀerent RF voltages applied to the trap
electrodes. Further optimization of the experimental
parameters, such as the applied laser power, number oftrapped ions, and so on, is under investigation.
Along with the development of the neutralizer, an
RF cavity is being developed. We have designed the
RF cavity, whose resonance frequency is approximately
3 GHz, as a prototype. Currently, preparations to evaluate the performace of the cavity using an Rb vapor
enclosed glass cell is in progress now.
References
1) H. T. Duong et al., Nucl. Instrum. Methods Phys. Res.
A 325, 465 (1993).
2) D. J. Larson et al., Phys. Rev. Lett. 57, 70 (1986).

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Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Application of 21 O β-NMR spectroscopy to study the microscopic
properties of CuO single crystal
A. Gladkov,∗1 H. Yamazaki,∗1 Y. Ichikawa,∗1 A. Takamine,∗1 H. Nishibata,∗2 K. Asahi,∗1 K. Kawata,∗1,∗3
K. Imamura,∗1 M. Tajima,∗1 K. Tsubura,∗1 S. Go,∗1 H. Endo,∗1 R. Mitsuyasu,∗1 K. Kikuchi,∗1 S. Takahashi,∗1
S. Akimoto,∗1 Y. Fukuzawa,∗1 M. Ito,∗1 M. Mukai,∗1 and H. Ueno∗1
Since the discovery of high-Tc superconductivity incuprates, copper ions coordinated by oxygen have been
extensively studied. The multiferroic phase of CuO exists between 213 K and 230 K, a much higher temperature range than the multiferroic phase of other known
compounds. When the temperature of the CuO sample is decreased from T > 230 K (the paramagnetic
phase) to 230 K > T > 213 K (the multiferroic phase),
it is expected that the electric ﬁeld gradient (EFG)at oxygen sites will be changed due to the multiferroictransition. By substituting the O sites in CuO with polarized 21 O ions, this hypothesized change in EFG canbe detected by the β-detected nuclear quadrupole resonance (β-NQR) method, providing the microscopic information on the “improper” ferroelectric phase. The
advantages of using 21 O relative to other oxygen isotopes have been discussed in a previous report.1)
Previously, we have successfully measured theground-state magnetic dipole and electric quadrupole
moments of 21 O2,3) by means of β-detected nuclear
magnetic resonance (β-NMR) spectroscopy. Thus, inthe present study, the microscopic properties of CuO
are investigated by using the 21 O isotope as a spectroscopic probe.
The experiment was carried out using the RIPS separator at the RIBF facility. The experimental settings for the production of spin-polarized 21 O secondary fragments were the same as the optimized settings for the previously conducted measurement of
the quadrupole moment in TiO2 single crystal.2) A
21
O beam was produced in the projectile fragmentation reaction of a 22 Ne beam at 70 MeV/nucleon on
2
a 185 mg/cm Be target. The momentum windowand emission angle of the secondary fragments wereselected to be pF = p0 × (0.97 ± 0.03) and θF > 1.5◦ ,respectively.
The secondary beam of 21 O was then puriﬁed by the
RIPS separator and implanted into the single-crystal
CuO sample located in the cryostat in the center ofthe β-NMR apparatus. The well-established method of
β-NMR/NQR spectroscopy4) in combination with the
adiabatic fast passage technique5) was used to measure
the anticipated change in the EFG around the 210–
230 K temperature region.
In order to record a successful β-NQR measurement,
it is important to know the EFG orientation through∗1∗2∗3

RIKEN Nishina Center
Department of Physics, Kyushu University
Center for Nuclear Study, University of Tokyo- 128 -

Fig. 1. An image of the sample of single-crystal CuO usedin the present experiment.

out the sample. For this purpose, the present sampleof the single-crystal CuO has been studied using scanning electron microscope imaging, before being placedin the experimental setup so that the main componentof the EFG is parallel to the static magnetic ﬁeld. The
β-NQR measurements of the EFG have been obtainedat diﬀerent temperatures in the multiferroic phase region, as well as at 100 K and at room temperature.
Unlike the 21 O β-NMR measurements for the TiO2
crystal, where a prominent resonant spectrum was directly observed, no resonance could be distinguishedfrom the measurements of the single-crystal CuO. The
obtained β-NMR spectra require further comprehensive analysis to be able to determine the microscopic
properties of CuO. This work is in progress and theresults will be reported in due course.
References
1) T. Kimura et al., Nat. Mater. 7, 291 (2008).
2) A. Gladkov et al., RIKEN Accel. Prog. Rep. 54, 28(2021).
3) Y. Ishibashi et al., Phys. Rev. C 107, 024306 (2023).
4) D. Nagae et al., Nucl. Instrum. Methods Phys. Res. B
266, 4612 (2008).
5) A. Abragam, The Principles of Nuclear Magnetism(Clarendon, Oxford, 1961).

Ⅲ-1. Atomic & Solid State Physics (Ion)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Precise measurement of diﬀraction structures in capillary laser sightfor ion microbeam irradiation to mammalian cells
M. Kurino,∗1,∗2 T. Ikeda,∗2,∗1 K. Inayoshi,∗1,∗2 R. Otani,∗1,∗2 and W. -G. Jin∗1
Glass capillary optics has been utilized in emitting
ion microbeam (µm-order diameter) irradiation to single mammalian cells and Escherichia coli cells at the
RIKEN Pelletron accelerator facility in the Nishina
R&D Building.1) The typical ion energy is a few MeV
whose range in water is from 10 to 100 µm for a H ion
and approximately 10 µm for a He ion. The ranges areclose to cell sizes, and are controlled with 1 µm resolution by selecting an appropriate initial energy. To
avoid mis-hitting the target area in ion irradiation, alaser sighting operation will be performed2) prior to theion shooting, which is realized by a dual-microbeam
capillary optics method. However, the micrometersized spot of the laser-sight encompasses not only thecenter spot but also surrounding ring structures, whichcauses a larger laser spot and increases the mis-hitting
probability. Here, we report a new precise laser spot
mapping method and analyze the decomposition of thediﬀraction pattern. Figure 1 shows the experimental
setup implemented at Toho University. A laser beamfrom an Ar+ laser source enters the glass capillary optics. A digital camera equipped with a transmissive
screen or power meter probe was located at a distanceof 65–70 mm downstream of the capillary outlet. Figure 2(a) depicts a typical ring pattern taken by thecamera, showing the center spot, thin rings, and brightring groups. We aim to investigate (1) the origin of
the thin rings, (2) dependence of the diameters of the
1st and 2nd bright ring groups on capillary outlet sizea, and (3) power ratio of each group. Accordingly, a
power meter probe with a 70 µmϕ-aperture was newly
installed to measure the absolute value of power density driven by a 2-dimentional high position-resolution(0.5 µm) stage. The green curve with dots connectedby lines depicted in Fig. 2(b) denotes the measured
power density along a horizontal line including the

Fig. 1. Setup of the laser microbeam proﬁle measurement.
∗1∗2

Department of Physics, Toho University
RIKEN Nishina Center- 129 -

Fig. 2. (a) Photo of typical ring pattern. (b) Power density
as a function of ka sin θ, showing measured (green) andﬁtted Gaussian peaks (orange), as well as Fraunhofer
diﬀraction model in a logarithmic scale (red). (c) Comparison of the ring diameters according to the outlet
size a.

spot center deﬁned in Fig. 2(a) for a capillary witha = 94 µm. Horizontal axis is in the unit of ka sin θ,
where k is wave number and θ is the probe angle inFig. 1. Each Gaussian peak comprises more than 10
measurement points, which are large enough to use ﬁtting methods. The thin rings in Fig. 2(a) are assumed
to extend beyond the 2nd bright ring group. However,the spread is hidden behind the bright rings. To remove the bright rings from the green curve, they wereexpressed as 5 and 3 Gaussian peaks, and the shapes
were determined by ﬁtting. The solid blue curve represents the result of subtracting of the Gaussian peaks(orange) from the green curve. The ﬁtting did not impose a Fraunhofer condition; however, the oscillation
period of the blue curve is the same as that of the
Fraunhofer model (red). Although the decay of the(dashed) curve seems to be slower than that of the red
curve, the behavior of blue curve including the center spot is similar to a Fraunhofer model. The slow
decay might be due to the focused light beam inside
the capillary body. Using the precise peak positionsof the bright ring groups, it was found that the diameters of the groups increase with a (Fig. 2(c)), while
the ratios of the diameters of 2nd to 1st groups remains constant with respect to a. The power ratios
of 0th, 1st, and 2nd groups were also obtained. The

Ⅲ-1. Atomic & Solid State Physics (Ion)

RIKEN Accel. Prog. Rep. 56 (2023)

ratio of the 0th spot was 37% of the entire spot for
a = 96 µm. However, a ratio of 62% was achieved forsmaller a = 70 µm. This means a smaller microbeam
has less power of bright ring groups. In conclusion,
the thin rings originate in the Fraunhofer diﬀraction
at the outlet. To obtain a high-contrast laser microspot with smaller bright ring groups, it is necessary to
use the capillaries with smaller outlets.
References
1) T. Ikeda, Quantum Beam Sci. 4, 1 (2020).
2) K. Inayoshi et al., RIKEN Accel. Prog. Rep. 55, 107(2022).

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2. Atomic and Solid State Physics (Muon)

Ⅲ-2. Atomic & Solid State Physics (Muon)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

DFT investigations on magnetic properties with Muon in La2 CuO4
using LSDA + U functional
S. Charoenphon,∗1,∗2 P. Reunchan,∗1 and I. Watanabe∗2Lanthanum cuprate (La2 CuO4 , LCO) is a typical
Mott insulator exhibiting a strong covalent state of Cu3d with O-2p within the two-dimensional (2D) CuO2
plane. In a previous study, LCO has been well investigated experimentally and theoretically; however, questions regarding electromagnetic states remain unanswered. The primary concern is the on-site Coulomb
potential, U, and the covalent state of the electronic
orbitals of Cu. The muon spin resonance technique(µSR) can provide information on local magnetic ﬁelds
at the muon site. However, obtaining the muon effect in the structure.5) In this study, we apply thedensity functional theory (DFT) + U to comprehensively investigate the electronic structure surrounding
the muon. Our attempt to solve the problem within
the DFT framework has yielded mixed results. Notably, most studies have attempted to correct the antiferromagnetic (AFM) ground state model of LCO andhave failed to provide a handle on the key experimentally observed properties of LCO. More speciﬁcally,
the local-spin-density approximation (LSDA) incorrectly predicts LCO to be nonmagnetic (NM) metals
in complete disagreement with the experimental value.
The generalized gradient approximation (GGA) produces a weak AFM. Thus, the development of methods
that have stronger electron correlations to stabilize theAFM ground state is necessary. DFT + U is a methodthat was proposed to improve the strong correlation
system.6) Among the most implemented methods inthe DFT + U realm is the LSDA + U method.
The DFT calculation was performed using the
RIKEN-integrated HOKUSAI Supercomputing Facility. Ab initio calculations were performed in the Vienna ab initio simulation package (VASP) with an energy cutoﬀ of 400 eV for the plane-wave basis set. We
employed the Hubbard parameter U = 4.87 eV.4) We
use a 28-atoms primitive cell with a 6×6×3 Γ -centeredk-point mesh for the Brillouin zone integrations to calculate the fundamental properties of LCO shown in
Fig. 1(a). In addition, a supercell structure containing
252 atoms (3 × 3 × 1 unit cell) was adopted for a calculation to consider the eﬀect of the relaxation of muon
position.
The lattice parameters calculated based on LSDA
+ U, band gap, and magnetic moment are listed inTable 1. The experimental values. The calculated
bandgap was obtained as 1.15 eV, slightly higher thanthe experimental value of 1 eV.3) Next step, the LSDA
+ U was conducted, including the muon, to repro∗1∗2

RIKEN Nishina Center
Department of Physics, Kasetsart University- 131 -

Fig. 1. (a) Crystal structure of LCO in the LTO phase withcopper, oxygen, and lanthanum atom indicated as blue,
red, and green spheres, respectively. (b) Schematic ofa CuO6 octahedral showing the O apical site and Cu,
O in the planar site. (c) Electrostatic potential calculation result. The grey sphere indicates three localminimum potential positions as candidates for initial
muon-stopped positions.

Table 1. Calculation of structural parameter, band gap,
and magnetic moment of a unit cell of LCO.
Function

The bandMagnetica

Lattice parameterbcgap (eV)moment (µB)

Exp.

5.35715.406113.1431130.48 ± 0.152

LSDA+U

5.196

5.246

12.903

1.15

0.469

duce the µSR results. We estimate the initial positionof muon injection in LCO obtained from the electrostatic potential. There are three possible local minimum potential positions that the muons can stop ina structure: M1, M2, and M3 as shown in Fig. 1(c),compared with muon spin resonance technique µSR results.4,5) Our method is fundamentally similar to the
GGA functional method4) except for the diﬀerence inthe functional. This is important for investigating theeﬀect of the diﬀerence in the functional in the previous
result.
The ﬁnal muon position and local deformations of
the crystal structure estimated from our LSDA + U +µ calculations are shown in Fig. 2. We calculated themagnetic moment of Cu without muon to be 0.450 µB .
Following relaxation, the magnetic moment calculationof Cu changed to 0.414, 0.453, and 0.449 µB for M1,
M2, and M3, respectively.

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 56 (2023)

Fig. 2. (a) Structure of LCO without muon. The ﬁnal
muon position after relaxation for (b) M1, (c) M2, and(d) M3, respectively. The Grey spheres indicate theinitial position. The black spheres indicate the ﬁnal
position of the muon after relaxation.

In conclusion, the role of muon perturbation was
found to deform the local crystal structure in the immediate vicinity of the muon. This eﬀect resulted in aslight reduction in the magnetic moment surrounding
the muon. Moreover, a new result is that LSDA + U
is clearly proven to be not suitable for describing theelectronic state of a strongly correlated system, particularly LCO.
References
1) M. Reehuis et al., Phys. Rev. B 73, 144513 (2006).
2) D. Vaknin et al., Phys. Rev. Lett. 58, 2802 (1987).
3) S. Uchida et al., Phys. Rev. B 43, 7942 (1991).
4) R. Ramadhan et al., Phys. Rev. R 4, 033044 (2022).
5) J. S. Möller et al., Phys. Scr. 88, 068510 (2013).
6) M. Yu et al., npj Comput. Mater. 6, 180 (2020).

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Ⅲ-2. Atomic & Solid State Physics (Muon)
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Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

The eﬀect of particle size on magnetic properties regarding La2 CuO4
nanoparticles
A. E. Putri,∗1,∗2 B. Kurniawan,∗2 and I. Watanabe∗1
The nano size eﬀect is an interesting physical phenomenon because it shows unique properties comparedto those observed in a bulk condition. One example is
the gold (Au). When the particle size of Au was reduced
to be in the nano-scale size, ferromagnetic behavior
was observed, whose origin is still unknown.1) Changes
in magnetic properties due to particle size reductions
were also observed in the La-based high-Tc superconducting oxide, La2−x Srx CuO4 (LSCO).2) Synthesizing
LSCO nanoparticles experiences numerous diﬃculties
regarding the control of defects and impurities.3) Thus,
an investigation to optimize sample preparation is aprerequisite.
The La2 CuO4 (LCO), a parental compound of LSCO
exhibiting antiferromagnetic Mott insulator behavior at
TN ≈ 300 K,4) will be investigated considering a nanosize particle. LCO nanoparticle were synthesized using
sol-gel method with lanthanum oxide, La2 O3 (99.99%),
and cooper oxide, CuO (99.99%), as a raw material similar to a previous research.5) Particles size of LCO canbe controlled by varying the sintering temperature at
650◦ C, 700◦ C, 750◦ C, 800◦ C, and 1100◦ C over 6 hours
which produce 43 nm, 54 nm, 70 nm, 90 nm, and 161 nm
particle size, respectively. Rietveld reﬁnement method
is used to analyze the X-ray diﬀractometer (XRD) pattern, which exhibit an orthorhombic crystal structurewith Bmab-space group. Small impurities were detected at the lowest sintering temperature of 650◦ C,
which correspond to approximately 1.3% of La2 O3 coming from the raw material. Because La2 O3 has no magnetic component, the magnetic properties of this sample should not be aﬀected. The LCO particle size (D)estimated using the Debye Scherrer method is express
using the following equation:
D = κλ/β cos θ(1)where κ is the Scherrer constant (0.9), λ is the wavelength of Cu-Kα (1.5406 Å) obtained from XRD measurements, β denotes the full width of half maximum intensity observed from XRD pattern and θ is the Braggs
angle.
The La2 CuO4 is composed of a basic unit of CuO6 octahedron crystal structure, which has been thoroughly
investigated in the past. Changing the particle size of
LCO aﬀects the antiferromagnetic transition temperature (TN ), as shown in Fig 1. Reducing the particle
size of LCO up to 43 nm can decrease the TN down
to 65 K. This nano-size eﬀect was also investigated onmagnetic materials, such as CuO. Accordingly, it wasreported that the Néel temperature, TN , of CuO could∗1∗2

RIKEN Nishina Center
Department of Physics, Universitas Indonesia

Fig. 1. Particle size dependance of the antiferromagnetictransition temperature, determined from the χ measurement at 0.0001 T with zero ﬁeld cooled method using Superconducting Quantum Interference Device (SQUID)
magnetometer MPMS. The insert ﬁgure demonstrates
the temperature dependance of magnetic susceptibility
for sample A.

be reduced from 290 K down to 40 K when CuO particle size was reduced to approximately 5 nm.6) Thosestudies indicated that the magnetic exchange interaction would be aﬀected by the reduction of particle size.
The largest particle size exhibits a superconducting
state below 40 K, which corresponds to the transition
temperature of LSCO doped with 15% strontium.2) The
antiferromagnetic long-range order was suppressed andsuperconductivity occurred owing to the excess oxygen inside the LCO sample,7) which led to the phaseseparation of partial superconductivity. Interestingly,
reducing the particle size of LCO down to nano-size
suppressed the superconductivity behavior below 40 K,
which occurred owing to the excess oxygen. Otherwise,
magnetic susceptibility of LCO nanoparticle below 50 K
can be ﬁt using Curie-Weiss equation, showing that themagnetic free spins increase by decreasing the particle
size.
References
1) Y. Yamamoto et al., Phys. Rev. Lett. 93, 116801 (2004).
2) Y. Yin et al., Phys. Chem. C 117, 3028 (2013).
3) S. Winarsih et al., Mater. Sci. Forum 966, 357 (2019).
4) P. A. Lee, et al., Rev. Mod. Phys. 78 (2006).
5) A. E. Putri et al., Mater. Sci. Forum 1028, 44 (2021).
6) X. G. Zheng et al., Phys. Rev. B 72, 014464 (2005).
7) Y. Okajima et al., Physica C 282–287, 1319 (1997).

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Ⅲ-2. Atomic & Solid State Physics (Muon)

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RIKEN
Accel. Prog. Rep. 56 (2023)

Sample synthesis of Nd2 Ru2 O7 for researches by using quantum beams
M. A. Syakuur,∗1 U. Widyaiswari,∗1 and I. Watanabe∗1
The pyrochlore system, A2 B2 O7 , is a frustrated magnet with corner-sharing crystal structure.1) Frustrated
is deﬁned as a condition where a system cannot minimize its total energy.1) Frustration caused by the latticegeometry in the crystal structure is classiﬁed as geometrical frustration.
There are a series of A2 B2 O7 shows a variety of uniqueelectronic states. Among them, an interesting example
but not yet well studied is Nd2 Ru2 O7 , which shows amagnetic fragmentation state with a monopole or multipole state at the A site.2) This system has the Kramer’s
ion Nd at the A site and the 4d element Ru with a magnetic moment at the B site. The Ru magnetic momentshows a magnetic ordering below 145 K and the Nd magnetic moment indicates an ordered state as well below
2 K.2) An anomaly in the temperature dependence ofthe magnetic susceptibility was reported to be approximately 25 K. The origin of this anomaly was not clear
and show the sample dependence.3)
Mother materials of Nd2 O3 and RuO2 were used tosynthesize Nd2 Ru2 O7 . Hence the chemical reaction efﬁciency between Nd and Ru is not so good and the vaporization temperature of those elements is diﬀerent, it
is not so easy to obtain a single-phase sample even for a
powder one.
Furthermore, a single crystal is necessary toinvestigate the magnetic fragmentation and themonopole/multipole states. This has not yet beenachieved yet until now due to those diﬃculties of thesample synthesis. We are now trying to develop thesample synthesis method to get a single-phase powder
sample which is necessary for the single crystal growth.
We mixed the mother powder samples as much as possible by using a ball mill and adjusted the sintering temperature and atmospheric gases, and we conﬁrmed thatthe anomaly observed around 25 K was due to Nd3 RuO7
which showed a ferromagnetic ordering.3)
Figure 1(a), the results of the X-ray diﬀraction measurement show that there is no other phase besides
Nd2 Ru2 O7 for a mixing time of 12 hours. While themixing time using a ball mill for 6, 24, or 96 hours gives
rise to other phases besides Nd2 Ru2 O7 .
Figure 1(b), the temperature dependence of susceptibility graph, χ, shows a transition at 145 K which corresponds to the magnetic transition of Ru4+ momentsof Nd2 Ru2 O7 as reported in previous studies.2–5) Thismagnetic transition temperature decreases, with increasing ball mill time which is not good to maintain a single
phase sample. In this 12 hours ball mill sample, we conﬁrmed that there is no anomaly peak around 25 K whichcorresponds to other phases, namely Nd3 RuO7 .3)
By using this single phase sample, a single crystal synthesis process will then be carried out using the ﬂoat∗1

Fig. 1. (a) X-ray diﬀraction patterns of Nd2 Ru2 O7 . (b) Temperature dependence of the magnetic susceptibility, χ,measured from 2 to 300 K at H = 0.1 kOe.

ing zone method, Bridgman technique, and the complete
sealed sample cell with high temperature synthesis forresearches by using quantum beams such as neutron andmuon spin relaxation (µSR).
References
1) J. S. Gardner et al., Rev. Mod. Phys. 82, 53 (2010).
2) S. T. Ku et al., J. Phys. Condens. Matt. 30, 155601(2018).
3) Utami et al., Mater. Sci. Forum 1028, 3 (2021).
4) M. Gaultois et al., J. Phys. Condens. Matt. 25, 186004(2013).
5) N. Taira et al., J. Solid State Chem. 152, 441 (2000).

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Ⅲ-2. Atomic & Solid State Physics (Muon)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Probing internal ﬁelds induced by Ru and Nd spin ordering on
Nd2 Ru2 O7 using continuous muon beam
U. Widyaiswari,∗1,∗2 H. Sakai,∗3 N. Hanasaki,∗3 and I. Watanabe∗1,∗2
Pyrochlore oxides have the general formula A2 B2 O7(A = trivalent rare-earth ion; B = tetravalent transition metal ion), with corner-sharing tetrahedral lattice
networks of A and B sites.1) The magnetic frustration,competition between the exchange and dipolar interactions, and crystal electric ﬁeld eﬀect control the natureof the ground state of the pyrochlore oxide.2)
Nd pyrochlores have been intensively investigated owing to their exotic properties exhibiting the coexistence of static ordering and the dynamic behavior of
Nd spin.3–5) Nd2 Ru2 O7 is a stable Nd pyrochlore, inwhich both Nd and Ru are magnetic ions. The magnetic ground state of Nd2 Ru2 O7 is interesting from theperspective of research, as we may investigate the coupling between Nd and Ru spins and how it aﬀects thecoexistence of static and dynamic Nd spins. Nd2 Ru2 O7
exhibits a magnetic transition around 1.8 and 146 K, corresponding to the ordering of Nd and Ru spins, respectively.6–8) In addition to macroscopic measurements using, for example, the Magnetic Properties Measurement
System (MPMS), the magnetic properties of Nd2 Ru2 O7
were investigated using a local magnetic probe such as
muon spin relaxation (µSR) measurement. We explore
the ordering of both Ru and Nd spins using µSR and determine the internal ﬁeld induced by the ordered spins.
Polycrystalline Nd2 Ru2 O7 was prepared using a solidstate reaction method. From previous µSR measurements using a pulsed muon beam, we conﬁrmed the ordering of Ru and Nd spins based on the decrease in theinitial asymmetry.9) The decrease in the initial asymmetry indicates fast muon spin precession in the earlytime spectra. The expected internal ﬁeld surrounding
the muon-stopping site is higher than 500 G, beyond thetime window of the pulsed muon beam. Therefore, acontinuous muon beam is necessary to determine the internal ﬁeld induced by the ordering of Ru and Nd spins.
In this report, we present the µSR data obtained using
a continuous muon beam on the DOLLY and GPS spectrometers at Paul Scherrer Institute (PSI), Switzerland.
We measured the µSR time spectra in the zero-ﬁeld (ZF)
condition in the temperature range of 2–250 K on GPS,
whereas the time spectra below 3 K down to 0.3 K wereobtained on DOLLY.
Figure 1(a) and (b) display the ZF-µSR time spectra.
The appearance of the Ru order state was conﬁrmed by
the appearance of muon spin precession below 145 K.
Below 120 K, a beating pattern appears in the oscillatingtime spectra, indicating two frequencies of muon spin
∗1
∗2
∗3

RIKEN Nishina Center
Department of Condensed Matter Physics, Hokkaido University
Department of Physics, Graduate School of Science, Osaka
University

Fig. 1. (a) ZF-µSR time spectra of Nd2 Ru2 O7 from 250 K
down to 0.27 K. (b) ZF-µSR time spectra of Nd2 Ru2 O7
below 2 K indicates a change in the frequency of the muon
spin precession.

precession associated with the two internal ﬁelds. The
origin of these two internal ﬁelds might be attributed
to two muon-stopping sites or two sources of the ﬁeld.
Because at a high-temperature range, only the Ru spins
were ordered, the internal ﬁelds were attributed to thetwo muon-stopping sites. A linearity exists between thetwo internal ﬁelds down to 2 K. Below 2 K, one frequency
becomes more prominent than the other one, and thelinearity of these two ﬁelds is broken. The enhancementof the internal ﬁeld below 2 K might be related to theordering of Nd spins.
References
1) J. S. Gardner et al., Rev. Mod. Phys. 82, 53 (2010).
2) B. C. Dem Hertog et al., Phys. Rev. Lett. 84, 3430 (2000).
3) J. Xu et al., Phys. Rev. B 94, 064425 (2016).
4) S. Petit et al., Nat. Phys. 12, 746 (2016).
5) V. K. Anand et al., Phys. Rev. B 95, 224420 (2017).
6) S. T. Ku et al., J. Phys. Condens. Matt. 30, 155601 (2018).
7) M. W. Gaultois et al., J. Phys. Condens. Matt. 25, 186004(2013).
8) U. Widyaiswari et al., Mater. Sci. Forum 1028, 3 (2021).
9) U. Widyaiswari et al., RIKEN Accel. Prog. Rep. 55, 110(2022).

- 135 -

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Magnetic short-range order in a hyperkagome lattice alloy Mn3 CoSi
D. P. Sari,∗1 H. Yamauchi,∗2 A. E. Hall,∗3 K. M. Kojima,∗4 D. Arseneau,∗4 G. Morris,∗4 B. Hitti,∗4 A. Berlie,∗5
I. Watanabe,∗6 P. -T. Hsu,∗7 Y. -S. Chen,∗8 M. K. Lee,∗7 B. Geetha,∗3 L. -J. Chang,∗7,∗9 and S. Shamoto∗7,∗10,∗11
We found a magnetic short-range order (SRO) in a
hyperkagome lattice alloy of Mn3 RhSi up to 720 K.1)
The onset temperature is the highest among any magnets, to our knowledge. Because of the historical record,
the magnetic cluster may be topologically protected in aparamagnetic state. To reveal the possible mechanism,
we have studied Mn3 TX (T: Co, Rh, and Ir, X: Si andGe) family alloys by µSR, where the cubic lattice parameter varies together with the electronic bandwidth. The
lattice parameter of Mn3 CoSi is close to that of β-Mn,
which is known as a non-Fermi liquid and spin-liquid
candidate compound.2,3) The β-Mn is also the heavy
electron metal (γ = 70 mJ/Mn K2 ).3) Mn3 CoSi withthe smallest cubic lattice parameter (a = 6.26 Å) locates near the quantum critical point, then with increasing the cubic lattice parameter, the magnetic transition
temperature increases, and the electronic speciﬁc heat γ
decreases in the Mn3 TX system. In the case of Mn3 RhSi
with a lattice parameter of a = 6.45 Å, the Néel temperature TN becomes 190 K and γ decreases to 12.1 mJ/Mn
K2 . Our magnetic pair distribution function analysis revealed that the magnetic SRO originated from the othermagnetic structure diﬀerent from the long-range order(LRO) magnetic structure.4) In addition, a similar magnetic SRO is recently discovered in a skyrmion alloy
Co7 Zn7 Mn6 with the same β-Mn structure.5)
Here, we report the µSR result of the single crystal
Mn3 CoSi measured at M20 of TRIUMF (M2201) and
ARGUS of ISIS (2070006). The transverse ﬁeld (TF)
time spectra of Mn3 CoSi were analyzed using a Gaussian damped oscillation function. The temperature dependence in Fig. 1 clearly shows the drop in the initialasymmetry. The onset temperature is about 240 K. Figure 2 shows the phase diagram of the Mn3 TSi system.
The result suggests that SRO and LRO temperatures
decrease to a quantum critical point. In addition, theinitial asymmetry drop also decreases to the quantum
critical point. The ratios were about 20% and 1% for
Mn3 RhSi and Mn3 CoSi, respectively.
In summary, we have studied Mn3 CoSi crystal by µSR.
The SRO and LRO temperatures depend on the lat∗1

Department of Physics, Shibaura Institute of Technology
Material Science Research Center, Japan Atomic Energy
Agency∗3 Department of Physics, University of Warwick∗4 Physical Sciences Division, TRIUMF∗5 RAL, ISIS
∗6 RIKEN Nishina Center∗7 Department of Physics, National Cheng Kung University∗8 National Synchrotron Radiation Research Center (NSRRC)∗9 Institute of Physics, Academia Sinica Academia Sinica∗10 Comprehensive Research Organization for Science and Society(CROSS)∗11 Advanced Science Research Center, Japan Atomic Energy
Agency∗2

Fig. 1. Initial asymmetry obtained from the Mn3 RhSi single
crystal under a transverse magnetic ﬁeld of 20 G.

Fig. 2. Tentative phase diagram of Mn3 TSi system.

tice parameter, suggesting the bandwidth eﬀect. To further explore the magnetic SRO, it is necessary for us to
study Mn3 IrSi with a lattice parameter of a = 6.50 Å byµSR. These alloys have spiral structures of Mn triangularunits, resulting in the noncentrosymmetric space group.
Neutron scattering measurements may be required to
study further the magnetic SRO related to a topologicalmagnetic cluster by using single crystals. We acknowledge the present µSR measurements at M20 of TRIUMF(M2201) in 2022 and ARGUS of ISIS (2070006) in 2020.
References
1) H. Yamauchi et al., Commun. Math. Phys. 1, 43 (2020).
2) J. R. Stewart et al., Phys. Rev. Lett. 89, 186403 (2002).
3) H. Nakamura et al., J. Phys. Condens. Matt. 9, 4701
(1997).
4) K. Kodama et al., J. Phys. Soc. Jpn. 90, 074710 (2021).
5) V. Ukleev et al., npj Quantum Mater. 6, 40 (2021).

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Ⅲ-2. Atomic & Solid State Physics (Muon)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

TF-µSR study of YbCu4 Ni
T. Taniguchi,∗1 K. Osato,∗1,∗2 H. Okabe,∗1 J. Nakamura,∗3 A. Koda,∗3 and M. Fujita∗1
Several examples of quantum critical phenomena
have been reported in f electron systems.1) The reason
is that the energy scale is so small that it can be controlled by the pressure and magnetic ﬁeld generated ina laboratory system. Thus, it is an ideal situation forinvestigating quantum critical phenomena as a whole.
However, there are few examples of materials near thequantum critical point at ambient pressure and zeromagnetic ﬁeld. Therefore, the search for such materials is a signiﬁcant challenge..
We focused on YbCu4 Ni, which has a large electronic
speciﬁc heat coeﬃcient.2) Recently, we have succeeded
in synthesizing pure materials. We have also succeededin using YbCu4 Ni as a magnetic refrigeration material by exploring its large electronic speciﬁc heat coeﬃcient.3) However, there are two possible origins of
the large value: (i) Kondo disorder, (ii) quantum criticality. To determine the actual origin, we performed
TF-µSR experiments.
The purpose of this study is to determine the origin of the large electronic speciﬁc heat coeﬃcient of
YbCu4 Ni. The linewidth of the µSR spectrum increases with a decrease in the temperature when the
Kondo disorder is dominant, as noted in previous studies on UCu4 Pd,4,5) CeRhRuSi2 ,6) and YbRh2 Si2 .7) To
obtain the information on YbCu4 Ni, we compared theµSR spectra at 10 K and 35 mK under TF-300 G. TheµSR measurements were performed with a dilution refrigerator using the D1 µSR spectrometer at Materrials and Life Science Experimental Facility (MLF) in
J-PARC, Japan. The powder sample was placed on asilver plate and covered with silver foil.
Figure 1 shows the 10 K and 35 mK µSR spectra; the spectrum at 35 mK is narrower than thatat 10 K. This rejects the main magnetic contribution of the Kondo disorder. Therefore, we determinedthat YbCu4 Ni is a quantum critical material. Previous studies on YbCu5−x Aux reported that the smaller
the lattice constant, the closer to the quantum criticalpoint.8–12) However, it is diﬃcult to syntheize the samples with small value of x because of the change in crystal structure at ambient pressure. Because YbCu4 Ni
has a smaller lattice constant than these samples, thequantum criticality may be observed at ambient pressure and zero magnetic ﬁeld.
In this study, we performed TF-µSR experiments toinvestigate the origin of the large electronic speciﬁcheat coeﬃcient of YbCu4 Ni. The spectrum at 35 mK
was observed to be narrower than that at 200 K, sug∗1∗2∗3

Institute for Materials Research, Tohoku University
Department of Physics, Tohoku University
Institute of Materials Structure Science, KEK- 137 -

Fig. 1. µSR spectra of YbCu4 Ni at 10 K and 35 mK.

gesting that YbCu4 Ni has a quantum criticality. In future studies, we will determine the origin of quantum
criticality by synthesizing pure single crystals and determining the band structure. Further, µSR measurements will be carried out in collaboration with KEK
and RIKEN groups.
We thank I. Watanabe from RIKEN and D. P. Sari
from College of Engineering Shibaura Institute ofTechnology for stimulating discussions. The µSR measurement at the Materials and Life Science Experimental Facility of J-PARC (Proposal No. 2022A0064) was
performed under user program.
References
1) G. R. Stewart, Rev. Mod. Phys. 56, 755 (1984).
2) J. G. Sereni et al., Phys. Rev. B 98, 094420 (2018).
3) Y. Shimura et al., J. Appl. Phys. 131, 013903 (2022).
4) D. E. MscLauglin et al., Phys. Rev. B 58, R11849(R)(1998).
5) D. E. MscLauglin et al., Physica B 289-290, 15 (2000).
6) C. -Y. Liu et al., Phys. Rev. B 61, 432 (2000).
7) K. Ishida et al., Phys. Rev. B 68, 184401 (2003).
8) K. Yoshimura et al., J. Alloys Compd. 317-318, 465(2001).
9) M. Giovannini et al., Intermetallics 16, 399 (2008).
10) P. Carretta et al., Phys. Rev. B 79, 020401(R) (2009).
11) I. C̆urlik et al., Phys. Rev. B 90, 224409 (2014).
12) M. Giovannini et al., J. Alloys Compd. 627, 20 (2015).

Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)µSR study of slightly pressurized organic superconductor
κ-(ET)4 Hg2.89 Br8 , II
D. P. Sari,∗1,∗2 Y. Cai,∗3,∗4 K. Kojima,∗3,∗4 I. Watanabe,∗2 Y. Ishii,∗1 and H. Taniguchi∗5Thehole-doped
organic
superconductor
κ-(ET)4 Hg2.89 Br8 , (κ-HgBr), where bis (ethylenedithio) tetrathiafulvalene is abbreviated as ET, is a key
to bridge the knowledge gap between half-ﬁlled organics and doped cuprate systems. Both κ-HgBr andcuprate superconductors exhibit a peculiar metallic
state at high temperature and pressure where theirresistivity exhibits a linear temperature dependence,ρ ∝ T ; this is non-Fermi-liquid (FL) behavior. In κHgBr, this non-FL region gradually changes to the FL
state by owing to pressure,1,2) similar to the change
in metallic state from optimally doped to overdoped
cuprates. A heat capacity study suggested that theenhanced antiferromagnetic ﬂuctuations toward lowtemperature cause the non-FL behavior of κ-HgBr.3)
This evidence may locate the superconducting κ-HgBrstate near the quantum critical point in between the
FL and localized states; incoherent conductivity wasobserved in its non-FL state.1,2) In this region, low
superﬂuid density was proposed by the macroscopic
measurement.4)
Our zero-ﬁeld µ+ SR experiment indicated that therelaxation rate from a temperature of approximately
10 K down to 0.3 K is temperature-independent.5) Thisis consistent with a superconducting state that preserves time-reversal symmetry. Furthermore, we measured the transverse-ﬁeld (TF) µ+ SR on ARGUS at
the RIKEN-RAL/ISIS muon facility. There was almost no change in the 10 mT of transverse-ﬁeld-µ+ SR
time spectra at 0.3 K and above superconducting (SC)temperature Tc = 4.6(3) K, indicating that the London penetration depth λbc , is longer than the order ofmicrometer, that is, low superﬂuid density. To conﬁrm this result, measurements using ano-ther geometric setup are necessary to minimize the sample misalignment and determine the absolute value of λbc .
Further, we performed the µ+ SR experiment at theM15 beamline at TRIUMF. The µ+ spin rotator wasused so that the sample setup illustrated in Fig. 1 could
be arranged. In all, 100 mg of the sample was used.
The plate-like crystals we aligned so that the magnetic
ﬁeld is perpendicular to the conducting bc-plane. Using this setup on the M15 beamline, the crystal misalignment can be minimized, and larger TF 10 times
higher than Hc1 = 25(5) Oe, which lies in the vortex
solid regime6) can be applied.
∗1
∗2
∗3
∗4
∗5

Fig. 1. Sample setup in the perpendicular mode µ+ [sr]stand for the muon beam with a spin rotator. In theperpendicular mode, the TF is applied perpendicular
to the plate-like conducting plane. The right panel displays a photograph of the sample setup on top of Ag
plate of the cryostat sample holder.

Furthermore, the bulk SC state must be conﬁrmed.
Therefore, we ﬁrst measure the TF-µ+ SR upon zeroﬁeld cooling and compare the spectra above and below Tc = 4.6(3) K. Figure 2 depicts the TF-µ+ SR
time spectra measured at 0.3 and 10 K under 50 mT,
respectively. The spectrum measured at 0.3 K wasclearly damped compared to that at 10 K owing to thebulk SC state. The spectra were analyzed by applying the Gaussian-type-damped cosine equation (represented by lines in Fig. 2) as,

Fig. 2. TF-µ+ SR time spectra upon zero-ﬁeld cooling in
κ-HgBr. The pink and cyan circles represent TF-µ+ SR
time spectra measured at 0.3 and 10 K, respectively.
The red and blue solid lines represent the ﬁtting lines
for the 0.3 and 10 K data, respectively.

A(t) = A1 exp[−σ 2 t2 ] cos(γµ B1 t + ϕ)
+ A2 cos(γµ B2 t + ϕ),College of Engineering, Shibaura Institute of Technology
Meson Science Laboratory, RIKEN
SBQM Institute, University British Columbia
CMMS, TRIUMF
Department of Physics, Saitama University(1)

where the ﬁrst and second terms on the right-hand side

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Ⅲ-2. Atomic & Solid State Physics (Muon)

RIKEN Accel. Prog. Rep. 56 (2023)

describe muon components from the sample and background, respectively. The damping rate σ at 0.3 K wasdetermined as 0.53 µs−1 . The next step is to measure
the temperature dependence of the London penetration depth in the vortex state under the ﬁeld coolingcondition.
References
1) H. Taniguchi et al., J. Phys. Soc. Jpn. 76, 113709(2007).
2) H. Oike et al., Nat. Commun. 8, 756 (2017).
3) A. Naito et al., Phys. Rev. B 71, 054514 (2005).
4) K. Wakamatsu et al., arXiv.2201.10714.
5) D. P. Sari et al., J. Phys. Conf. Ser. 2462, 012061(2023).
6) D. P. Sari et al., in Materials Science Forum, Vol. 966(Trans Tech Publications Ltd., Sanur, Bali, Indonesia,2019), p. 296.

2

- 139 -

3. Radiochemistry and Nuclear ChemistryⅢ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Extraction behavior of Nb and Ta in HF solution with F-form
TOMA resin
S. Goto∗1 and M. Higuchi∗1∗1

Kd for 95g Nb and 179 Ta were obtained from the following equation:
Kd =(Aini − Aa )/mr,Aa /Va(1)where the subscripts a and r represent the aqueous
phase and the resin, respectively, for the radioactivity
A, mass m, and volume V . Aini is the radioactivity
relative to the control sample.
According to the reported dissociation constant forhydroﬂuoric acid,4) the anions originating from HF aremostly HF−
2 at the concentrationns of HF in this study.
The dependence of Kd on the HF−
2 concentration isshown in Fig. 1. For both Nb and Ta, Kd was smallerin pure hydroﬂuoric acid than in the aqueous phase
containing Cl− . This may indicate a diﬀerence in theadsorption of Cl− and HF−
2 on the resin. However,further investigation is needed because the formationof complexes containing Cl is also possible when Clform resins were used.

106
105

Kd / mL g–1

Elements with atomic numbers ≥104 are called superheavy elements. The purpose of Db chemistry research is to investigate the relativistic eﬀects of orbital
electrons, which are more pronounced in heavier elements. Furthermore, in the search for new elements, if
the anchor nucleus (last nucleus in the observed decay
chain) is a neutron-rich Db isotope, the chemical identity of the Db can determine the formation of the newelement, because such isotopes have a relatively long
half-life.
Group 5 elements, including Db in hydroﬂuoric acid,form ﬂuorine-containing complexes very quickly, making this reaction system suitable for on-line chemical
experiments with short-lived Db isotopes. However,group 5 elements may also form oxyﬂuoride complexes,
thus a method to identify the chemical species is desired.1) We have studied solid-phase extraction of Nb
and Ta anion complexes from hydroﬂuoric acid using
Aliquat 336-supported resin.2) This extraction systemdiﬀers from anion exchange in that the distribution coeﬃcients of Nb is very diﬀerent from Ta; however, theextracted chemical species are not yet clearly known.
The resin used in this study was trioctyl methyl ammonium chloride (TOMA-Cl), one of the main components of Aliquat 336. The counter ions in Aliquat
336 and TOMA are generally chloride ions. In orderto clarify the eﬀect of chloride ions in solid-phase extraction with hydroﬂuoric acid, we prepared resins inwhich the chloride ion was replaced with an anion originating from the hydroﬂuoric acid, and investigated theextraction behavior of Nb and Ta.
Radiotracers, 95g Nb (T1/2 = 34.991 d) and 179 Ta(T1/2 = 1.82 y), were produced with deuteron irradiation on Zr and Hf metallic foil targets with natural isotopic abundance, respectively, using the RIKEN K70
AVF cyclotron. The radiotracers in the targets werechemically isolated by anion exchange. The 40-wt%
TOMA-Cl resin was prepared by mixing TOMA-Cl
dissolved in methanol with MCI GEL CHP20/P30 for
approximately 1 day.3) To obtain Cl− free F-type resin
the TOMA-Cl resin was shaken well with 10 M HF, andthen dried. A 400 µL of 1–27 M HF solution containing 95g Nb and 179 Ta tracers was shaken with approximately 11 mg of TOMA resin for 1 h using a syringeless ﬁlter. After ﬁltering the resin, the 250 µL solution
was aliquoted and the radioactivity was measured withan HPGe detector. Aqueous solution control samples
without resin were also measured to determine the radioactivity of the resin. The distribution coeﬃcients
Graduate School of Science and Technology, Niigata University- 141 -

104
103
102
101
100 -2
10

10-1
100
–
[HF2 ] / M

101

Fig. 1. Dependence of the distribution coeﬃcients Kd forNb (black) and Ta (red) on [HF−2 ] with F-type (solid
symbols) and Cl-type (hollow symbols) TOMA resins.

References
1) O. L. Keller, Jr., Inorg. Chem. 2, 783 (1963).
2) D. Sato et al., RIKEN Accel. Prog. Rep. 50, 246 (2017).
3) H. Haba et al., Radiochim. Acta 95, 1 (2007).
4) H. H. Broene et al., J. Am. Chem. Soc. 69, 1644 (1947).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Online solid-liquid extraction of 255 No with the polymer-supported
crown ether
E. Watanabe,∗1,∗2 R. Nakanishi,∗1,∗2 S. Otaka,∗1,∗2 R. Wang,∗1,∗2 Y. Itakura,∗2,∗3 R. Masuda,∗1,∗2 Y. Shigekawa,∗2
A. Nambu,∗2 X. Yin,∗2 T. Yokokita,∗4 H. Haba,∗2 A. Shinohara,∗1,∗5 and Y. Kasamatsu∗1,∗2

∗1
∗2
∗3
∗4
∗5

Graduate School of Science, Osaka University
RIKEN Nishina Center
School of Science, Osaka University
Salesian Polytechnic
Osaka Aoyama University

the automated rapid α/SF detection system.
After α-particle measurement, we measured γ-ray activities of 162 Yb in the samples with Ge detectors to
calculate the chemical yield of each extraction.
We carried out 48 extraction and 24 control cycles
and observed a total of 173 α events from the decay of
255
No, as shown in Fig. 1. The production cross-sectionof 255 No was estimated to be approximately 500 nb, andthe value is consistent with that determined in the previous report.7) The half-life of 255 No was estimated to be212±24 s, which is in good agreement with the previously
reported value (211 ± 11 s).8) The Kd value of 154, 155 Er
and 254, 255 Fm (byproduct α-emitters) is ∼1 mL g−1 ,which is within the value of other f-block elements previously reported.4) Thus, it was demonstrated that the αevents in the region of interest for 255 No in the α-particle
spectrum properly originate from only 255 No and that reliable Kd values were obtained in the present solid-liquid
extraction experiments using AMBER. The Kd values ofNo are under estimation.

CountsNobelium (No) is an actinide element with an atomic
number of 102. In aqueous solutions, No is considered to form a +2 valence state stably, while other f block elements are stable at +3 or higher valence states.
Previous ion-exchange experiments have reported thatNo exhibits similar chemical behavior to that of Ca2+and Sr2+ .1) Our group has recently demonstrated that
No2+ shows diﬀerent coprecipitation behavior from alkaline earth metal ions, using the samarium hydroxide
coprecipitation method.2) Further systematic studies areneeded on No2+ compared with the group II elementsfrom the viewpoint of molecular structure in the solution and its electronic structure.
We focus on solid-liquid extraction using the polymersupported
crown
ether.
The
Sr
resin (Eichrom Inc.)
contains 4,4′ (5′ )-di-tertbutylcyclohexano-18-crown-6 ether (DtBuCH18C6) andhas strong extraction selectivity for Sr2+ . The selectivity of alkaline earth ion is aﬀected by a changes in theacidity of a liquid phase and its concentration.3,4) In theextraction in HNO3 system, the extracted species of Sr
is deduced to be Sr(NO3 )2 DtBuCH18C6.5) Previously,
we found that the extraction reaction of alkaline earth
elements with the Sr resin rapidly (∼1 min) reached theequilibrium state and the solid-liquid extraction is suitable for 255 No experiment. We have obtained the distribution coeﬃcients (Kd ) of Ca, Sr, Ba, and Ra with the
Sr resin in HNO3 , HCl, and HClO4 as comparison data
for No.
In this work, we performed online solid-liquid extraction experiments with 255 No to obtain its Kd values andto investigate the complexation between No2+ and DtBuCH18C6. To obtain the Kd values of No under equilibrium state, we used a batch-type solid-liquid extraction apparatus called AMBER.6)
We produced 255 No (T1/2 = 211 s) and 162 Yb(T1/2 = 18.9 min) by the 248 Cm(12 C, 5n)255 No andnat
Gd(12 C, xn)162 Yb reactions with the AVF cyclotron
at RIKEN. The reaction products were transported by
the He/KCl gas-jet system to the chemistry room anddissolved in 3.5 MHNO3 or 7.6 M HCl solutions. The
solution sample was injected into a chemical reaction
container containing the Sr resin. After shaking thecontainer for 60 or 180 s, only the solution phase wasdischarged from the container through a PTFE ﬁlter.
Subsequently, the discharged sample was evaporated todryness and subjected to alpha particle measurement by

255No

Energy / keV
Fig. 1. α-spectrum for 255 No obtained in control experiment
without the resin with 60-s shaking.

In the future, we will discuss the extraction behaviorof No based on the comparison of the Kd values of 255 No
with those of alkaline earth metal ions. Additionally, we
will perform relativistic quantum chemical calculations
and analyze the electronic states of extracted species ofNo.
References
1) R. J. Silva et al., J. Inorg. Nucl. Chem. 38, 1207 (1976).
2) H. Ninomiya et al., RIKEN Accel. Prog. Rep. 52, 184(2019).
3) E. P. Horwitz et al., Solv. Extr. Ion Exch. 10, 313 (1992).
4) D. V. Filosofov et al., Solv. Extr. Ion Exch. 33, 496 (2015).
5) M. L. Dietz et al., Talanta 62, 109 (2004).
6) Y. Kasamatsu et al., Radiochim. Acta 103, 513 (2015).
7) T. Sikkeland et al., Phys. Rev. 172, 1232 (1968).
8) M. Asai et al., Phys. Rev. C 83, 1 (2011).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Coprecipitation behavior of element 102, nobelium, with barium
sulfateS. Otaka,∗1,∗2 E. Watanabe,∗1,∗2 R. Nakanishi,∗1,∗2 R. Masuda,∗1,∗2 R. Wang,∗1,∗2 Y. Itakura,∗2,∗3
T. Yokokita,∗2,∗4 Y. Shigekawa,∗2 A. Nambu,∗2 X. Yin,∗2 H. Haba,∗2 A. Shinohara,∗5 and Y. Kasamatsu∗1,∗2

∗1
∗2
∗3
∗4
∗5

determining the total amount of dissolved species (astandard sample is prepared), the reaction products
were dissolved in dilute HCl solution, and the solution
was put on a Ta plate. The sample was evaporated todryness by He gas at 600◦ C and a halogen heat lamp.
Finally, these dried precipitated and standard samples
were subjected to alpha-particle measurement by theautomated rapid alpha/SF detection system. After thealpha-particle measurement, gamma-ray activities of162
Yb in the samples were measured with a Ge detector to monitor the chemical yields and coprecipitation
behavior of Yb.
We successfully prepared 17 coprecipitated samples
and 41 standard samples. Alpha-particle spectrum
for the standard samples is shown in Fig. 1. Basedon the alpha counts, we estimated the coprecipitation
yields of 255 No and 162 Yb, considering various corrections such as the diﬀerences in the cooling times before the measurements and detection eﬃciency. As aresult, a high coprecipitation yield of around 80% was
obtained for 255 No in the case of adding 2.0 M ammonium sulfate. A detailed analysis is underway. We
plan to discuss the sulfate complexation properties of255
No based on the comparison with those of alkaline
earth metal elements. In addition, we will compare theresults with those obtained by quantum chemical calculations which were previously performed4) to discuss
the chemical bonding properties of No.

10
255

8

CountsThe orbital electrons of heavy elements with Z ≥101, synthesized by heavy-ion-induced nuclear reactions, are aﬀected by signiﬁcant relativistic eﬀects.
Therefore, the chemical properties of the heavy elements might be diﬀerent from those expected from theperiodicity of the homologues in the periodic table,
and it is very interesting to investigate their chemical
behavior.
We focus on element 102, nobelium (No). No isreported to exist as M2+ ion in aqueous solutions,whereas the other heavy actinides all form M3+ .1,2) In
the previous chemical experiments on No, the behaviorof No was compared with those of divalent transition
metal elements and the alkaline earth metal, barium(Ba). As a result, it has been reported that No behaves similarly to Ba. Thereafter, No was reported
to have similar chemical behavior to those of calcium(Ca) and strontium (Sr), which have similar ionic radii
to No, instead of other alkaline earth metal elements.4)
Recently, our research group focused on sulfate precipitates of alkaline earth metal elements and established
the barium-sulfate-coprecipitation method which is applicable to No.3) According to the results obtained in
the preliminary experiments with Ca, Sr, Ba, and Ra,
we found that the precipitation behavior in the present
reaction system is sensitive to the ionic radii of the alkaline earth metal elements. In addition, it is expectedthat a diﬀerence in chemical bonding properties of No
from those of alkaline earth metal elements will be observed. In this study, we applied the above method toNo.
We produced 255 No (T1/2 = 211 s) and 162 Yb(T1/2 = 18.9 min) by the 248 Cm(12 C, 5n)255 No andnat
Gd(12 C, xn)162 Yb reactions, respectively, using the
AVF cyclotron at RIKEN RIBF. The reaction products were transported by the He/KCl gas-jet system tothe chemistry room and dissolved in a dilute HCl solution. When a precipitated sample is prepared, 20 µgof Ba and 2 mL of 0.1 M or 2.0 M ammonium sulfate
were added into the dissolved solution in a 5-mL microtube, and the solution was stirred for 5 min at room
temperature using a Vortex mixer. Then, the solution
containing the precipitate was ﬁltrated using the suction ﬁltration apparatus controlled by PC. The precipitated sample was dried with He gas at 100◦ C. When

214

No

Po

6
4
2
0

7500

8000
Energy /keV

8500

Fig. 1. Alpha-particle spectrum for the 255 No standard
sample.

References
1) J. Maly et al., Science 160, 1114 (1963).
2) G. T. Seaborg, in The Transuranium Elements(McGraw-Hill, New York, 1949), p.1492.
3) R. J. Silva et al., Inorg. Chem. 13, 2233 (1974).
4) S. Hayami, MS thesis, Osaka University (2021).

Graduate School of Science, Osaka University
RIKEN Nishina Center
Department of Chemistry, Osaka University
Salesian Polytechnic
Osaka Aoyama University- 143 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Coprecipitation of 133 Ba, 226 Ra, and 152 Eu with calcium oxalate forthe chemical study of nobelium
R. Nakanishi,∗1,∗2 E. Watanabe,∗1,∗2 S. Otaka,∗1,∗2 R. Masuda,∗1,∗2 R. Wang,∗1,∗2 Y. Itakura,∗2,∗3
T. Yokokita,∗2,∗4 Y. Shigekawa,∗2 A. Nambu,∗2 X. Yin,∗2 H. Haba,∗2 A. Shinohara,∗5 and Y. Kasamatsu∗1,∗2
Superheavy elements (SHEs) with Z ≥ 101 are synthesized by heavy-ion-induced nuclear reactions. The
production rates of these elements are very low, andtheir half-lives are usually short.1) Therefore, it is difﬁcult to investigate their chemical properties. Element
102, nobelium (No), is one of the actinide elements. No
has unique property that the element exists stably as
No2+ ion in aqueous solutions,2) whereas all lanthanide
and actinide elements have the most stable valency of+3 or higher. Previous chemical studies on No havereported that No exhibits similar chemical behavior tothose of the group 2 elements in the periodic table.3) In
this study, we focused on oxalic acid, which precipitates
the group 2 elements by bonding with metal ions, andmalonic acid, which has a slightly longer carbon chain
length than oxalic acid. We expect that the complexation behavior of these dicarboxylic acids with No can beinvestigated by the coprecipitation method. Studies forcomplexation with organic ligands are scarce in SHE
chemistry, and through the present study, the dependence of the No behavior on the ligand size and shapeis expected to be discussed. In this report, we present
the results of the precipitation and coprecipitation experiments of Ca, Sr, Ba, Ra, and Eu with oxalic acid.
We determined the suitable experimental conditions forinvestigating the properties of No-oxalic complexes.
Oxalic acid precipitation experiments for Ca, Sr, andBa were performed to determine the carrier metal elements that rapidly and fully precipitate by bonding
with oxalic acid. The precipitation experiments were
performed at pH = 2, 3, 4, and 5 with reaction timesof 3 min. 5 mL of 2 mM Ca2+ , Sr2+ , or Ba2+ hydrochloric acid (pH = 2, 3, 4, or 5) was mixed with
5 mL of 4, 20, and 200 mM oxalic acid (pH = 2, 3, 4,or 5). The amounts of Ca and Sr in the precipitate andﬁltrate samples were analyzed by EDTA titration andthat of Ba was determined by γ-ray measurement for133
Ba tracer with a Ge semiconductor detector. The
precipitation yields were estimated from the amounts.
Based on the precipitation results, coprecipitation experiments of 133 Ba, 226 Ra, and 152 Eu with calcium oxalate were performed using Ca as the carrier at pH = 3.
20 µL of hydrochloric acid (pH = 3) containing 133 Ba,
226
Ra, and 152 Eu was added to 230 µL of 2.17 mM Ca2+hydrochloric acid (pH = 3), which was followed by addition of 250 µL of 20 and 200 mM oxalic acid (pH =
∗1
∗2
∗3
∗4
∗5

3). The mixture was shaken for 5 min. The coprecipitation yield of each element was determined by γ-ray
measurement for 133 Ba and 152 Eu with the Ge semiconductor detector, and by α-particle measurement with a
Si detector for 226 Ra.
The results of the oxalic acid precipitation experiments of Ca, Sr, and Ba showed that the precipitation
yield of Ca rapidly reached about 100%, and a clear difference in the precipitation yields of Ca (92.6 ± 4.9%),
Sr (5.8%), and Ba (0.6 ± 0.3%) was observed under
the condition of 10 mM oxalic acid at pH = 3. Consequently, we determined suitable experimental conditions, as Ca carrier will be used in coprecipitation at pH= 3, to observe the similarity of No behavior to whichgroup 2 element.
Figure 1 shows the coprecipitation yields of 133 Ba,
226
Ra, and 152 Eu with calcium oxalate. The yields for133
Ba and 226 Ra were low and increased with increasing
oxalic acid concentration, in the range 10–40% for 133 Ba
and 5–20% for 226 Ra. The coprecipitation yields for152
Eu were over ∼90% at all oxalic acid concentrations
studied. The coprecipitation yields were in the order ofCa ≈ 152 Eu > 133 Ba > 226 Ra, which is inverse orderof the ionic radius4) : Ca2+ (1.12 Å) ≈ Eu3+ (1.066
Å) < Ba2+ (1.42 Å) < Ra2+ (1.48 Å). This suggeststhat smaller metal ions tend to match the size of oxalic
acid and stably form complexes. We plan to investigate
the coprecipitation behavior of No with oxalic acid to
discuss the ionic radius of No.

Fig. 1. Coprecipitation yield of 133 Ba, 226 Ra, and 152 Eu.

References
1) J. Maly et al., Science 160, 1114 (1963).
2) A. Toyoshima et al., J. Am. Chem. Soc. 131, 9180
(2009).
3) R. J. Silva et al., Inorg. Chem. 13, 2233 (1974).
4) R. D. Shannon, Acta Cryst. A 32, 751 (1976).

Graduate School of Science, Osaka University
RIKEN Nishina Center
Department of Chemistry, Osaka University
Salesian Polytechnic
Osaka Aoyama University- 144 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Improved chemical separation scheme of Pa isotopes from a 232 Th
target toward observing the radiative decay of 229m Th using 229 Pa
Y. Shigekawa,∗1 X. Yin,∗1 A. Nambu,∗1 Y. Wang,∗1 and H. Haba∗1
The ﬁrst excited state of the 229 Th nucleus (229m Th)
has an excitation energy of ∼8.3 eV (150 nm),1) potentially leading to an ultraprecise nuclear clock. We aim
to observe the radiative decay (γ rays) of 229m Th anddetermine its radiative half-life; this is an importantparameter to develop the nuclear clock by doping a
CaF2 crystal with 229 Pa, which decays to 229m Th withnegligibly small recoil energy.2–4) In a previous study,4)
we ionized 233 Pa and implanted it into a CaF2 crystal
with a total eﬃciency of 0.53(1)% using the surface
ionization technique. However, when we tried the ionization and implantation of 229 Pa that was producedin the 232 Th(p, 4n)229 Pa reaction and chemically puriﬁed,3) the eﬃciency was limited to ∼0.1%. A probable reason for the low eﬃciency is that some amountof 232 Th and impurities remain in the puriﬁed 229 Pa
solution and inhibit the ionization of Pa. Therefore,
we improved the chemical separation scheme in thisstudy by adding a separation step using the CL resin(Triskem).5) Moreover, for faster separation, we increased the ﬂow rate of eluents during column chromatography by a factor of ∼10, compared with ourprevious separation experiments.2,3)
The chemical separation scheme was developed
using 230 Pa (T1/2 = 17.4 d) and 233 Pa (T1/2= 27.0 d) produced in the 232 Th(d, 4n)230 Pa and232
Th(d, n)233 Pa reactions at the RIKEN AVF cyclotron. Two 232 Th foils (70 mg/cm2 × 2, ∼140 mg)
were irradiated with 9.1 µA of a 24-MeV deuteronbeam for 70 min. The foils were dissolved with concentrated HCl and 0.05 M (NH4 )2 SiF6 6) 62 days after
the irradiation. The chemical separation of the Pa isotopes was performed following the scheme shown in
Fig. 1, which consists of three column separations using anion-exchange resin (Column A and C) and the
CL resin (Column B). The ﬂow rate of every eluent
was set to 1–2 mL/min by pushing the air in the column using a peristaltic pump. The radioactivity of Pa
isotopes and ﬁssion products (FPs) for each fraction
was measured via γ-ray spectroscopy using a Ge detector to check chemical yields and radioactive impurities.
The ﬁnal Pa fraction was subjected to inductively coupled plasma mass spectrometry (ICP-MS) to check thechemical purity.
The separation by Column A removed the majority of 232 Th and FPs, and the Pa fraction that eluted
from Column A included radioactive impurities of 95 Zr(T1/2 = 64.0 d), 95 Nb (T1/2 = 35.0 d), and 103 Ru (T1/2= 39.2 d). The separation with Column B reduced∗1

RIKEN Nishina Center- 145 -

Fig. 1. Chemical separation scheme of Pa.

95

Zr and 103 Ru to levels less than the detection limits of the γ-ray measurement. 95 Nb, which behaves
similarly to Pa, was separated with Column C by adecontamination factor of 220, which is high enoughfor the experiment of 229 Pa. It was reported that Nb
can be separated with the Eichrom DGA resin;5) thus,
we checked the performance of this method. However,the decontamination factor was measured to be only
12, and thus, we selected the method in Fig. 1. The
chemical yields of Pa isotopes for Columns A, B, and C
were 95(4)%, 96(3)%, and 95(3)%, respectively (total
yield 86(5)%), meaning that the separation at the highﬂow rate does not lead to the loss of Pa. We expectthat the whole separation will be ﬁnished in ∼4 h,which is ∼3 times shorter than that of the previous
scheme, minimizing the decay loss of 229 Pa. For the
ICP-MS measurement of the puriﬁed Pa solution, theimpurities of >100 ng were Mg (627 ng), Al (284 ng),
Zn (141 ng), and Th (167 ng). Therefore, the amountⅢ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

of 232 Th was reduced to the same level as other impurities.
We are now developing a new Pa implantation apparatus that enables in varying the implantation energyof 229 Pa in the range of 0.5–30 keV, not limited to
15 keV.4) In a preliminary experiment using the puriﬁed 230, 233 Pa solution and the new apparatus, thetotal ion implantation eﬃciency was measured to be∼0.2%, which is higher than the previous value using
229
Pa (∼0.1%), probably due to the improved chemical
puriﬁcation scheme. Higher eﬃciency may be further
obtained by improving and optimizing the new apparatus.
References
1) B. Seiferle et al., Nature 573, 243 (2019).
2) Y. Shigekawa et al., RIKEN Accel. Prog. Rep. 54, 143(2021).
3) Y. Shigekawa et al., RIKEN Accel. Prog. Rep. 55, 124(2022).
4) Y. Shigekawa et al., RIKEN Accel. Prog. Rep. 55, 126(2022).
5) T. Mastren et al., Anal. Chem. 90, 7012 (2018).
6) V. Radchenko et al., Radiochim. Acta 104, 291 (2016).

2- 146 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Preparation of a small high-density 229 Th target for the X-ray
pumping of the 229 Th nuclear clock isomerY. Shigekawa,∗1 K. Okai,∗2 Y. Fukunaga,∗2 K. Yoshimura,∗2 and H. Haba∗1
The ﬁrst excited state of the 229 Th nucleus (229m Th)
has an excitation energy of ∼8.3 eV,1) which allows
laser excitation and spectroscopy of the nucleus. One
application is ultraprecise nuclear clocks with unprecedented uncertainty.2) Our group aims to observe the γrays emitted from 229m Th, which is an important stepfor realizing nuclear clocks. In 2019, we succeeded in
actively producing 229m Th by populating the 29.2-keVsecond excited state of 229 Th using X-rays at SPring8.3) With this technique, we are now trying to detect γrays of 229m Th produced in a 229 Th-doped CaF2 crystal, in which the internal conversion process of 229m Th
would be inhibited. For every beamtime at Spring-8,
we have to precisely adjust the energy of X-rays for the
resonant excitation of 229 Th to the 29.2-keV state. For
the energy adjustment, we have used a source containing 0.24 µg of 229 Th placed in a hole with a diameterof 0.4 mm on a graphite plate. Owing to the small
amount of 229 Th, searching for the resonant X-ray energy has required more than 14 h. The above 229 Th
source was prepared by performing the ∼7000 sets ofdropping a small amount of 229 Th solution (5 nL perdrop) into the hole and evaporating it by heating. The
amount of 229 Th that can be poured into the small
hole was limited because the nanoscale drop was notstable and the density of the 229 Th sample was lower
than expected, probably owing to the repeated rapid
evaporation processes. In this study, we developed a
new simple method and successfully prepared a small
high-density 229 Th source, which is used to search forthe resonant X-ray energy for the 29.2-keV state.
The new source-preparation method is drying one
drop (∼1 µL) of nitric acid containing 229 Th on a
Teﬂon plate. Owing to the high water repellency of
Teﬂon, the shape of the drop remains spherical during the evaporation process, and the drop size becomesmuch less than 1 mm just before it is completely dried.
We prepared two types of Teﬂon plates shown in Fig. 1.
The type A plate has a small taper hole made bydrilling, where the 229 Th solution is dropped. The holein the type B plate was manually prepared by heating
the Teﬂon plate and deforming it with a conical die.
We found that a drop on the type B plate was evaporated and retained a spherical shape. In contrast, adrop on the type A plate slightly expanded, and thesize of the residues became larger than 1 mm. The images obtained by scanning electron microscopy (SEM)
for the type A plate (Fig. 2) showed scratches made by∗1∗2

RIKEN Nishina Center
Research Institute for Interdisciplinary Science, Okayama
University- 147 -

Fig. 1. Schematics of the Teﬂon plates of types A (left) andB (right).

Fig. 2. SEM images of the Teﬂon plates of types A (left)
and B (right).

drilling, which would be the reason for the lower water
repellency. The type B plate showed a smooth surface(Fig. 2); thus, we adopted the type B plate to prepare
the 229 Th source.
229
Th was ﬁrst puriﬁed via anion exchange chromatography using high-purity acids (metal impurities<100 ppt). The puriﬁed 229 Th was dissolved with
10 µL of 1-M HNO3 . The solution was dropped ona Teﬂon sheet and evaporated. Then, the residue wasdissolved with 1 µL of 1-M HNO3 and dropped on thetype B plate placed on a hot plate. We washed theTeﬂon sheet with 1 µL of 1-M HNO3 , which was thenadded to the drop on the type B plate. The temperature of the hot plate was ﬁrst maintained at ∼45◦ C for
20 min to slowly evaporate the majority of the solution. It was then increased to ∼120◦ C over 11 min andmaintained at that temperature for 9 min. The temperature was then raised to 200◦ C over 13 min andmaintained at that temperature for 19 min for complete dryness.
The 229 Th source shown in Fig. 3 had a residue witha diameter of ∼0.7 mm. The amount of 229 Th in thesource was measured to be 1.61(2) µg by γ-ray spectroscopy, which is 6.7 times larger than the amountof the previous 229 Th source that we have used.3) Xray ﬂuorescent measurements performed at SPring-8
showed that a large amount of 229 Th was condensed
within a diameter of 0.65 mm. By using this new
229
Th source, we were able to ﬁnish the X-ray en-

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

ergy search for the excitation to the 29.2-keV state
four times faster than that for the previous source.

Fig. 3. Photograph of the prepared 229 Th target.

References
1) B. Seiferle et al., Nature 573, 243 (2019).
2) E. Peik et al., Europhys. Lett. 61, 181 (2003).
3) T. Masuda et al., Nature 573, 238 (2019).

2- 148 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Development of 211 Rn/211 At generator through liquid phase recoveryof radon and ionic liquid extraction of astatine
Y. Nagai,∗1 Y. Ganaha,∗1 A. Yokoyama,∗2,∗3 K. Washiyama,∗4 I. Nishinaka,∗5 X. Yin,∗3 A. Nambu,∗3
Y. Shigekawa,∗3 and H. Haba∗3
The short path length and high linear energy transfer of α particles are expected to facilitate targetedalpha therapy for the treatment of tumor. A promising nuclide among various α emitters is 211 At with ahalf-life of 7.21 h, which has gained popularity owing
to its appropriate life and potential to synthesize labeled compounds as a halogen element. This has led
to several preclinical studies on At chemistry.1) To improve the availability of 211 At, a 211 Rn/211 At generator
was developed via the extraction using organic solventof DIPE or MIBK for expanding nuclide production
away from accelerator facilities because 211 Rn, which
has a half-life of 14.6 h, is the parent nuclide of 211 At.2)
In this study, we proved the wet chemistry processes
through liquid phase recovery of radon and ionic liquid
extraction of astatine for the generator.
In recent years, ionic liquids have attracted attention
as an alternative to organic solvents from the perspective of green chemistry. Ionic liquids exist in the liquid
phase at room temperature, have low volatility, andare ﬂame-retardant; therefore, the environmental loador risk of accidents is minimal. Further, the amountof radioactive waste can be reduced compared to thatusing organic solvents owing to their repeated usability. In addition, ionic liquids are considered promisingsolvents for extracting 211 At as per the reports on radiation resistance.3)
The nuclide of 211 At was produced via the209
Bi(α, 2n) reaction at the RIKEN AVF cyclotron or
the decay of 211 Rn from the 209 Bi(7 Li, 5n) reaction at
the JAEA tandem Van de Graaﬀ accelerator. The irradiated Bi target was dissolved in 6 M HNO3 andﬁnally the 211 At nuclide was collected in dodecane solvent although the At species may diﬀer depending on
the procedures of preparation. The 211 At was further
extracted to 3 M HCl solution. Subsequently, 211 At
was extracted into an ionic liquid (IL) of [C8 mim]+[Tf2 N]− , where [C8 mim]+ and [Tf2 N]− are alkylimidazolium ion and bis (triﬂuoromethanesulfonyl) imide
ions, respectively. Finally, it was back-extracted into
0.1 M NaOH solutions. The α radioactivity of 211 At
was measured using a liquid scintillation counter to determine extraction rates of the nuclide for the relevant
∗1
∗2
∗3
∗4
∗5

Graduate School of Natural Science and Technology,
Kanazawa University
Institute of Science and Engineering, Kanazawa University
RIKEN Nishina Center
Fukushima Global Medical Science Center, Fukushima Medical University
Quantum Beam Science Research Directorate, National Institutes for Quantum Science and Technology- 149 -

extraction procedures.
Figure 1 shows the extraction rates of 211 At fromdodecane into HCl solution, from HCl solution into IL,
and from IL into NaOH solution. Species in dodecane
were found to be dependent on the preparation of At as
observed upon the comparison of the results. Following
the extraction in HCl solution, At species appeared tobehave in a similar manner.

Fig. 1. Extraction rates for At from the decay of Rn (Rn→ At) and directly produced At (At).

Figure 2 shows the same extraction rates of 211 At
from the decay of 211 Rn, as in Fig. 1, but for withand without H2 O2 as a reductant. Reduction of At
species enhanced extraction into HCl and worked theother way in back-extraction with NaOH. This suggests that solvent extraction in practical applications
necessitates the adjustment of chemical species to havea good recovery of At.

Fig. 2. Extraction rates for At from the decay of Rn withand withou without H2 O2 .

References
1) F. Guérard et al., Cancer Biother. Radiopharm. 28, 1(2013).
2) E. Maeda et al., J. Radioanal. Nucl. Chem. 303, 1465
(2015).
3) L. Yuan et al., J. Phys. Chem. B 113, 8948 (2009).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

The feasibility study for the medical radioisotope: astatine-211
production by the gas cell-based laser ionization technique
T. Sonoda,∗1 T. Nakashita,∗1 H. Haba,∗1 H. Tomita,∗2 and H. Ishiyama∗1
Astatine-211 is one of remarkable advantage isotopes for targeted α-particle therapy. RIKEN Nishina
Center has been providing many types of medical radioisotopes, particularly a large amount of 211 At.1)
Astatine-211 can be produced from natural bismuth
target via the 209 Bi(α, 2n)211 At nuclear reaction. The
adjustment of α-particle energy is constrained frommaximizing 211 At production to avoid production of
210
At, which yields the undesirable α-particle emitting
daughter, 210 Po. The chemical separation of 211 At and210
At is, in principle, incompatible in the recovery process of 211 At from the target.
Here, we propose a new idea to use the physicalseparation of 211 At and 210 At by the gas cell-basedlaser ionization technique. This technique utilizes anisotope separation by the element and mass selective
low-energy beam transportation. Figure 1 shows theconceptual diagram for this technique. The bismuth
target irradiated by the cyclotron beam is installed
into the gas cell. Atomic/ionic At or any other isotopes are evaporated from the target by resistive heattransfer and then they are transported to the exit areaby an inert gas ﬂow. Three-color pulsed laser beams
are sent to the gas cell exit area for laser ionizationof At.2) The laser wavelength enables element selec-

211At collection stage

quadrupole mass separator
211At-ion
210At-ionIon beam-guide(differential pumping)

Pump
Laser
ionization

tive ionization by using a resonant excitation scheme
in the atomic structure. The excitation energy forthe removal of single electron is acquired stepwise bylaser photons. Photo-ionized astatine isotopes are sent
to the quadrupole mass separator for the separationof 211 At and 210 At via multipole ion beam guide in
the diﬀerential pumping stage. Consequently, a highly
pure 211 At ion beam is collected. The radioactive contamination can be minimized by using the closed gas
circulation3) and by installing the entire system in a
draft chamber.
In 2023, we will start the feasibility study for thistechnique as the following steps:• Laser ionization test for astatine isotope in vacuum to investigate eﬃcient ionization scheme.
• Extraction and collection test for 211 At.
• Evaluation of the radioactive purity and collection
eﬃciency.
The potential advantage of this technique is expected in the following parts: (1) Facilitate use of thebest α-particle energy for the cyclotron for the maximum production of 211 At, without worrying about anyother isotope production, such as 210 At. This will result in 3-5 gain in the production eﬃciency. (2) Minimization in human exposure/contamination against alpha emitting radioactivity and radiation. For the ﬁrst
test, we will install the highly activated target into thegas cell manually. In future, the bismuth target including gas cell will be set on the beam axis of the cyclotron
beam line, then the gas cell unit can be treated insteadof dealing the target by human hands. This is crucial
if the cyclotron beam intensity is very high.
The feasibility study for new production techniqueof 211 At has been started. The fabrication and development of the whole system is in progress. If the feasibility is conﬁrmed, this technique will be extended toother medical radioisotope productions such as 213 Bi,
111
In, and 225 Ac.

Gas cellReferences
1) Y. Wang et al., RIKEN Accel. Prog. Rep. 53, 192(2019).
2) S. Rothe et al., Nat. Commun. 4, 1835 (2013).
3) T. Sonoda et al., Rev. Sci. Instrum. 87, 065104 (2016).

Draft chember
123
Laser system

Fig. 1. Conceptual diagram for 211 At production. The
whole system is as small as to be placed in the general draft chamber.
∗1∗2

RIKEN Nishina Center
Faculty of Engineering, Nagoya University- 150 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Progress of 211 At production at the RIKEN AVF cyclotron
X. Yin,∗1 N. Sato,∗1 A. Nambu,∗1 Y. Shigekawa,∗1 and H. Haba∗1
211

At is one of the most promising radionuclides
for targeted α-particle therapy. The most common
method for 211 At production is to irradiate natural
Bi with α particles via the 209 Bi(α, 2n)211 At reaction.
We have been developing production technologies of211
At at the RIKEN AVF cyclotron.1–3) In our current method,3) a metallic 209 Bi target with a typical
thickness of 20 mg/cm2 on a 1-mm Al backing is irradiated with a 28.0-MeV α beam at an angle of 15◦
to the beam axis. During the irradiation, the target iscooled with circulating water (1.5 L/min, 10◦ C) andHe gas (30 L/min). The maximum beam intensity of
10 particle µA (pµA) can produce 211 At with a thicktarget yield of 48 MBq/pµA h. After the irradiation,
the target was placed in a quartz tube, was heated
up to 850◦ C, and kept for 10 min with O2 -gas ﬂowing
at 10 mL/min. 211 At sublimated from the target wastrapped by a PFA tube cooled at −96◦ C. 200–400 µL
CHCl3 was used to wash the PFA tube to collect 211 At
in a glass v-vial. Finally, the CHCl3 solution was dried
to obtain a dry 211 At in the v-vial with N2 -gas ﬂowing
at 100 mL/min.
The demand for RIKEN 211 At is increasing every
year. It is desirable to increase the production yieldof 211 At by irradiating the 209 Bi target with a more
intense beam. Due to the poor thermal conductivity (9.79 W/(m·K)) and a low melting point (272◦ C)
of Bi, an eﬀective cooling system is essential. In thiswork, we modiﬁed the channel of the cooling water toincrease its ﬂow rate from 1.5 to 4.0 L/min. We also
lowered the temperature of the water from 10 to 5◦ C.
However, we could prepare only one dry 211 At in asingle drying and it took approximately 15 min to dry
200 µL of CHCl3 . To increase the productivity of thedry 211 At, we developed a rapid drying apparatus thatmakes it possible to simultaneously produce 4 v-vials
of dry 211 At within less time.
The 209 Bi targets with thicknesses of 17.7 mg/cm2
and 18.6 mg/cm2 were irradiated for 40 mins with a
28-MeV α beam using the previous and new irradiation systems, respectively. The beam intensity was
25 particle µA. After the irradiations, the targets were
subjected to γ-ray spectrometry to determine the activity of 211 At.
In a separate experiment, 642 MBq of 211 At in
300 µL of CHCl3 was divided into 3 v-vials of 100 µL
each and dried simultaneously in the rapid drying apparatus with N2 -gas ﬂowing at 3 L/min at room temperature and 100 kPa. The N2 gas was aspirated by achemical pump and exhausted through 1 M Na2 S2 O5solution and a charcoal trap (Fig. 1(b)). The v-vials∗1

RIKEN Nishina Center- 151 -

Fig. 1. (a) Photo and (b) schematic of rapid drying apparatus for 211 At.

were subjected to γ-ray spectrometry before and after
drying.
Figures 2(a) and 1(b) show photos of the irradiated 209 Bi targets with the previous and new irradiation systems, respectively. The target cooled with
1.5-L/min water at 10◦ C was damaged severely. The
produced 211 At activity of 503 ± 16 MBq is only 61%
compared with the theoretical yield.4) The damage ofthe target cooled with the 4.0-L/min water at 5◦ C
with the new system seems smaller, and the produced211
At activity of 667 ± 23 MBq is 82% of the theoretical yield.4) As expected, a higher ﬂow rate and lower
temperature of cooling water help to produce 211 At
more quantitatively. Our current production yield of
211
At (1.0 GBq/h at 28.0 MeV with a 25-particle µA αbeam) was increased by a factor of 2.1 compared to ourprevious one by a 10-particle µA α beam irradiation.1)

Fig. 2. Photos of the 209 Bi targets irradiated with the previous (a) and new (b) irradiation system at the 1.5 and
4.0 L/min ﬂow rate of cooling water, respectively.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

Each 100 µL of the 211 At CHCl3 solution in the 3v-vials was dried within 5 min. The activities of 211 At
before and after drying were consistent with each otherafter the decay corrections. With the rapid drying apparatus, the time required to dry 211 At was signiﬁcantly reduced.
References
1) N. Sato et al., RIKEN Accel. Prog. Rep. 50, 262 (2017).
2) S. Yano et al., RIKEN Accel. Prog. Rep. 50, 263 (2017).
3) Y. Wang et al., RIKEN Accel. Prog. Rep. 53, 192(2019).
4) S. M. Qaim et al., IAEA Technical Report Series
No.473, IAEA, Vienna, Austria (2011).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Improvement of chemical separation method for theranostic
radionuclide 141 Ce
K. Ooe,∗1 T. Watabe,∗2,∗3 Y. Shirakami,∗3 A. Nambu,∗4 H. Haba,∗4 and J. Hatazawa∗5

∗1
∗2
∗3
∗4
∗5

sample was subjected to γ-ray spectrometry with a Ge
detector for the determination of 141 Ce radioactivity.
After measurement with the Ge detector, the concentration of nat Ba in each eluted sample was measured
by ICP-MS.
The elution curves for nat Ba and 141 Ce, from the Ln
resin cartridge, were shown in Fig. 1. The time required for the separation of 141 Ce with the Ln resin
cartridge was less than 1 h, signiﬁcantly reduced compared to the previous study (approximately 4 h) byincreasing the eluent ﬂow rate. The most of nat Ba
was eluted at elution volume of around 15 mL with
0.03 M HCl. After elution of nat Ba, 141 Ce was recovered by elution with 1 M HCl. Although a small
amount of 141 Ce leakage was observed around 10 mL of
0.03 M HCl, probably due to the increased eluent ﬂow
rate, the recovery yield for 141 Ce with 1 M HCl was ashigh as 96%. The contamination of nat Ba in the 141 Ce
fractions was calculated to be approximately 0.6 µg
in the ICP-MS measurement, which is also improved
compared to the previous separation (contamination ofnat
Ba was approximately 3 µg).1) The separation factor of 141 Ce for Ba is estimated to be approximately
105 .

0.03 M HCl

100

Eluted amount of

natBa or 141Ce (%)

Radionuclides are widely used in the treatment oftumors. In Japan, all therapeutic radionuclides usedin clinical practice are imported from other countries.
Domestic production using accelerators is desirable fora stable supply of therapeutic radionuclides.
One of the candidate radionuclides for theranostics(therapeutics + diagnosis) that can be produced by using accelerators is cerium-141 (141 Ce, T1/2 = 32.5 d).
This nuclide emits β-particles (maximum β energy:
580.7 keV), which can be used for tumor therapy.
It also emits a γ-ray with an energy of 145.4 keV(branching ratio: 48.2%), which can be used for imaging by single photon emission computed tomography(SPECT). One of the production reactions for 141 Ceusing accelerators is the 138 Ba(α, n)141 Ce reaction.
However, 141 Ce has rarely been used in the ﬁeld of
nuclear medicine, and investigation of accelerator production and chemical separation conditions will be necessary.
We have previously reported the accelerator production and chemical separation of 141 Ce.1) BaO was selected as a suitable target material for the productionof 141 Ce by the α beam using an accelerator. Chemical separation of 141 Ce from the irradiated BaO target
was also achieved through column chromatography using a Ln resin (extraction chromatographic resin withdi (2-ethylhexyl) phosphoric acid). However, it tookapproximately 4 h for the chemical separation of 141 Ce
because there was no eluent pumping.
In this study, the rapid chemical separation of 141 Cefrom the Ba target using the Ln resin cartridge wasinvestigated with increasing eluent ﬂow rate.
141
Ce was produced in the nat Ba(α, xn)141 Ce reaction with a 29-MeV alpha beam using the RIKEN K70
AVF cyclotron. nat BaO pellet was used as the target
material. The irradiated nat Ba target (approximately
100 mg) was dissolved in 3 mL of 1 M HCl. After evaporation to dryness, the residue was dissolved in 10 mL
of 0.03 M HCl solution The solution was ﬁlled into a
10 mL syringe and then injected into the Ln resin cartridge column (resin volume: 2 mL) at a ﬂow rate of
1 drop per 1–2 seconds. Each 1 mL of the eluents wascorrected with sample tubes. The nat Ba was washedout from the cartridge with 0.03 M HCl, and then141
Ce was eluted with 1 M HCl solution. Each eluted
Radioisotope Research Center, Institute for Radiation Sciences, Osaka University
Department of Nuclear Medicine and Tracer Kinetics, Osaka
University Graduate School of Medicine
Institute for Radiation Sciences, Osaka University
RIKEN Nishina Center
Research Center for Nuclear Physics, Osaka University- 153 -

1 M HCl

141Ce (γ-ray spectrometry)80

natBa (ICP-MS)

60
40
20
0

0

5

10 15 20 25
Elution volume (mL)30

Fig. 1. Elution curves of nat Ba and 141 Ce in chromatographic separation with Ln resin cartridge.

In the next study, the radiopharmaceutical labeling of 141 Ce using DOTA (1, 4, 7, 10Tetraazacyclododecane-1, 4, 7, 10-tetraacetic Acid),which is widely used for chelate labeling of therapeutic
radionuclides, will be investigated.
Reference
1) K. Ooe et al., RIKEN Accel. Prog. Rep. 55, 130 (2022).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Chemical separation of 139 Ce from a nat La target using LN resin
K. Akiyama,∗1,∗2 A. Tamura,∗1 and H. Haba∗2
Endohedral metallofullerenes are clathrate compounds in which metal atoms and metal carbon clusters are included in a fullerene, which is a cage-likemolecule composed of sp2 carbons.1) In particular, radioactive metallofullerenes encapsulating radioisotopes(RIs) are expected to be applied to radiopharmaceuticals such as a drug delivery system for transportingan RI to aﬀected organs by chemical modiﬁcation of
the fullerene surface. We have studied the productionof endohedral metallofullerenes containing lanthanide
and actinide elements and their chemical properties. In
these studies, it is necessary to use well-characterizedradioactive Ce-encapsulated metallofullerenes as thecomparators for the metallofullerenes encapsulating
RIs which are carrier-free or without any stable isotopes such as promethium and actinide elements. So
far, we have used chemically separated 139 Ce producedby the 139 La(d, 2n)139 Ce reaction in the RIKEN AVF
cyclotron with the target material of nat La for our metallofullerene research.2) However, it is necessary to use
the highly toxic K2 Cr2 O7 as an oxidizing agent for Ce
in the solvent extraction method by di-(2-ethylhexyl)
phosphoric acid (HDEHP), which we employed so far,and is not preferable for the application of radioactive
metallofullerenes for nuclear medicine in future work.
Therefore, we use LN resin (Eichrom Technologies,Inc.) (see Fig. 1), which is an extraction chromatography resin specialized for the separation of rare-earth
elements using HDEHP, for the separation of 139 Cefrom a target material containing La in large quantities. The purpose of this work was to separate andpurify a trace amount of 139 Ce from La as a target byextraction chromatography using LN resin.

Fig. 2. Elution behavior of 139 Ce on LN resin. The shaded
fractions indicate the fractions containing La, as conﬁrmed by UV/vis absorption. The radioactivity in eachfraction was normalized to that of loaded 139 Ce.

Fig. 1. Structure of the LN resin extractant.

About 1 g of a La plate as a target was irradiatedwith 24 MeV deuterons at a beam intensity of 5 µA in
the RIKEN AVF cyclotron, and 139 Ce was produced by∗1∗2

the 139 La(d, 2n)139 Ce reaction. The irradiated La target was dissolved in concentrated nitric acid to obtain a
139
Ce solution. A polyethylene column with a hight of
50 mm and a diameter of 7 mm was ﬁlled with LN resin
and loaded with 100 µL of 139 Ce solution. A total of
25 mL of 0.15 M nitric acid was added to this column,
and the eluate was collected every 5 mL. Then, a totalof 10 mL of 6 M nitric acid was added to wash the column. Gamma rays with an energy of 165 keV of 139 Ceemitted from each fraction were measured with a Ge
semiconductor detector. After gamma-ray measurement, 4-(2-pyridylazo) resorcinol (PAR) was added toeach fraction to conﬁrm the elution position of La by
the ultraviolet/visible (UV/vis) absorption.
Figure 2 shows the elution behavior of 139 Ce during
extraction chromatography, monitored by the relative
radioactivity of 165 keV emitted from each fraction.
The shaded fractions indicate the fractions containing
La conﬁrmed by UV/vis absorption. From these results, it is found that 139 Ce was suﬃciently separated
from La and that the proposed separation method
is excellent for the separation of 139 Ce from a large
amount of La used as a target material. Using thispuriﬁed 139 Ce, we are currently researching metallofullerenes encapsulating 143 Pm and carrier-free endohedral metallofullerenes encapsulating 177 Lu.

Department of Chemistry, Tokyo Metropolitan University
RIKEN Nishina Center- 154 -

References
1) H. Shinohara, Rep. Prog. Phys. 63, 843 (2000).
2) K. Akiyama et al., RIKEN Accel. Prog. Rep. 53, 194(2019).

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Astatine-211-labeled gold nanoparticles for targeted alpha-particle
therapy via intravenous injection†
X. Huang,∗1 K. Kaneda-Nakashima,∗2,∗3 Y. Kadonaga,∗4 K. Kabayama,∗1,∗2,∗3 A. Shimoyama,∗1,∗2,∗3
K. Ooe,∗2,∗3 H. Kato,∗4 A. Toyoshima,∗2,∗3 A. Shinohara,∗2,∗5 H. Haba,∗6 Y. Wang,∗6 and K. Fukase∗1,∗2,∗3

†
∗1
∗2
∗3
∗4
∗5
∗6

Condensed from the article in Pharmaceutics 14, 2705
(2022)
Graduate School of Science, Osaka University
Institute for Radiation Sciences, Osaka University
Forefront Research Center, Osaka University
Graduate School of Medicine, Osaka University
Osaka Aoyama University
RIKEN Nishina Center- 155 -

5 nm 211 At-AuNPs@H16, and 5 nm 211 At-AuNPs@
H16/RGD), as shown in Fig. 1, can be labeled with211
At in a high RCY.

(a)

Active targeting nanoparticles(Tumor pH or receptor binding)

Passive targeting nanoparticles(EPR effect)

M. W. 6000

5 nm AuNPs@mPEG
RCY: 99%

10000

M. W. 2000
In 0.1M PBS pH 6.0

M. W. 6000

30 nm AuNPs@mPEG
RCY: 99%

5 nm AuNPs@H16
RCY: 92%

(b)

CTL

(c)

5
4..0

1 MBq

3.5
Weight (g)1000

M. W. 2000
In 0.1M PBS pH 6.0

5 nm AuNPs@H16 /RGD
RCY: 93%

4.5

0.5 MBq
Tumor volume (mm3)

Recently, much attention has been directed towards
the powerful cancer therapeutic potential of targetedalpha-particle therapy (TAT). Globally, particularly inJapan, the α-particle emitting radionuclide astatine211 (211 At) has garnered signiﬁcant attention for its
use in TAT.
One of the crucial challenges in TAT is the delivery of 211 At to the tumor tissues. In a previous study,
we discovered that 211 At could be eﬃciently incorporated into gold nanoparticles (AuNPs) through a simple mixing process for 5 min, leading to a high radiochemical yield (RCY) without the need for puriﬁcation. Furthermore, our research revealed that the intratumoral administration of 211 At-AuNPs eﬀectively
suppresse tumor growth and demonstrate the stabilityof 211 At-AuNPs in the body.1) For systemic metastatic
tumors, intravenous injection is a promising method ofdelivery. In this study, we investigated the substantial
potential of AuNPs as carriers for the targeted deliveryof 211 At via intravenous administration.
211
At was produced at RIKEN using a short-lived
RI supply platform. The separation and puriﬁcationof 211 At was achieved through dry distillation. Fourtypes of functional AuNPs were synthesized throughsurface modiﬁcation using methoxy polyethylene glycol (mPEG) or tumor-targeting peptides (H16 or
RGD). The astatine labeling reaction was evaluatedusing centrifugation, as described previously.1)
Tumor xenograft models were established thoroughthe subcutaneous transplantation of human pancreatic cancer cells (PANC-1) in BALB/c-nu/nu mouse.
Four types of 211 At-AuNPs were administered to
PANC-1 xenograft mice to evaluate their biodistribution at 3 and 24 h. The treatment eﬀect of 5 nm
211
At-AuNPs@mPEG was evaluated using the PANC1 xenograft model. All the animal experiments wereconducted according to the guidelines of the Animal
Research: Reporting In Vivo Experiments and the Osaka University Animal Experiment Regulations, andapproved by the Osaka University Animal ExperimentCommittee.
Four types of 211 At-labeled functional AuNPs (5 nm
211
At-AuNPs@mPEG, 30 nm 211 At-AuNPs@mPEG,

100

3
2.5
2
1.5
1
0.5

10

0

7

14

21

Days after injection

28

0

CTL

0.5 MBq

1 MBq

Treatment

Fig. 1. (a) Four types of 211 At-labeled functional AuNPs
designed for the study.
(b) Change in the tumor size following the administration of 5 nm 211 AtAuNPs@mPEG or control (CTL) (saline). (c) Weightof enucleated tumors 30 d after injection.

The in vivo biodistribution results indicated a higher
accumulation of 5 nm 211 At-AuNPs@mPEG in tumors(2.25%ID/g) in 3 h when compared with 30 nm 211 AtAuNPs@mPEG based on the enhanced permeability
and retention (EPR) eﬀect with a long retention timein tumors for 24 h. The intravenous administration of
5 nm 211 At-AuNPs@mPEG was found to signiﬁcantly
inhibit tumor growth in a pancreatic cancer model.
Gold nanoparticles (AuNPs) are an ideal carrier for211
At delivery, owing to their facile and eﬃcient synthesis processes and high stability. The results of thisstudy indicate that the intravenous administration of
5 nm 211 At-AuNPs@mPEG exhibits a potent antitumor eﬀect. These results provide a novel framework
for the design of nanoparticles suitable for targetedalpha-particle therapy via intravenous injection.2)
References
1) H. Kato et al., J. Nanobiotechnology 19, 1 (2021).
2) X. Huang et al., Pharmaceutics 14, 2705 (2022).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Eﬃcacy of nuclear medicine therapy with 67 CuCl2 in mice bearing
LS180 colon cancer
Y. Fujisawa,∗1 Y. Sugiura,∗1 H. Haba,∗2 A. Nambu,∗2 Y. Shigekawa,∗2 X. Yin,∗2 Y. Magata,∗3 and Y. Iida∗1
67

CuCl2 intravenously. Saline-treated mice were used
as a control. Mice were weighed and tumor diameters were recorded regularly. The diameters of tumorswere measured with a caliper, and tumor volumes
were determined using the formula: (longer diameter)× (shorter diameter)2 /2. This study was performedin accordance with the recommendations by the Guide
for the Care and Use of Laboratory Animals of the
Suzuka University of Medical Science.
67
CuCl2 showed high accumulation in the tumor,
6.50 ± 2.34, 6.85 ± 1.83, and 5375 ± 1.26% ID/g at
1, 24, and 48 h after administration, as shown in aprevious study. Tumor size reduction was observed in
all mice treated with 67 CuCl2 (Fig. 1). However, but
relatively signiﬁcant weight loss was also observed inthem (Fig. 2). Therefore, 67 Cu is a promising RI for3

t u m o r v o lu m e ( m m )

4000

3000

2000

1000

*

*

0
0

2

4

6

8

10

12

14

d a y s a f te r a d m in is t r a tio n

Fig. 1. Therapeutic studies of 67 CuCl2 in LS180 tumorbearing mice. (•; saline (n = 7), △; 67 CuCl2 (n = 4).
*, p < 0.05 (2-way ANOVA followed by sidack-test).

1 .1

b o d y w e ig h t r a t io

Nuclear medicine is one of the eﬀective methods forearly diagnosis and therapy of cancer, and various radioisotopes (RI) have been used. Among them, radioactive Cu is expected to be a promising RI withdiagnostic and therapeutic properties. Radioactive Cu
includes 60 Cu, 61 Cu, 62 Cu, and 64 Cu, which are eﬀective for PET diagnosis, and 67 Cu, which can be applied
for treatment. 67 Cu is a therapeutic radionuclide thatemits β-particles of energy 0.392 to 0.577 MeV with ahalf-life of 61.8 h. Although the β-particle energy of67
Cu is low, it is expected to be eﬀective in treatingsmall cancers.1) RIs that have high-energy β-particles,
such as 90 Y, show a good therapeutic eﬀect, but theyalso have a large eﬀect on surrounding tissues, andthe injected dose is limited by exposure to other organs.2) 67 Cu has a low-energy β-particles and can beadministered in large doses, leading to eﬀective and efﬁcient treatment.3) Another advantage of 67 Cu is theability to calculate exposure doses accurately. Injected
doses of radiopharmaceuticals used in nuclear medicine
therapy are calculated from the exposure doses. 67 Culabeled drugs can accurately calculate the exposure
doses with 64 Cu-labeled ones, contributing to safe andeﬀective personalized medicine.
Various studies have been conducted on cancer diagnosis and therapy using radioactive Cu-labeled drugs,
and in recent years, the possibility of PET diagnosis
using 64 CuCl2 has been demonstrated. Copper transporter protein 1 (CTR1) is overexpressed in various
cancers, suggesting that 64 Cu accumulates in cancer
via CTR1.4) Based on these studies, the tumor accumulation of 67 CuCl2 was also evaluated, and it was
found to have the same pharmacokinetics as 64 CuCl2 .5)
In this study, we investigated the therapeutic eﬀect of67
CuCl2 on tumor-bearing mice to clarify the potentialof cancer therapy using 67 CuCl2 .
Tumor-bearing mice were prepared by implantationof LS180 tumor cells (5 × 106 cells) in 0.1 mL PBS
into the ﬂanks of nude mice (BALB/c-nu/nu, male).
Biodistribution experiments were performed by intravenously administering 67 CuCl2 . The mice were killed
at 1, 24 and 48 h after administration, and tissuesof interest were excised and weighed before their radioactivity was measured. LS180 tumors were grownin BALB/c mice in the same way for therapeutic studies. Mice were administered with 17.0–23.2 MBq of

1 .0

0 .9

*
*

0 .8

*

*

0 .7
0

2

4

6

8

10

12

14

d a y s a f te r a d m in is t r a tio n

∗1
∗2
∗3

Faculty of Pharmaceutical Sciences, Suzuka University of
Medical Science
RIKEN Nishina Center
Department of Molecular Imaging, Hamamatsu University
School of Medicine- 156 -

Fig. 2. Changes in body weight of mice after saline or67
CuCl2 administration. (•; saline (n = 7), △; 67 CuCl2(n = 4). *, p < 0.05 (2-way ANOVA followed by sidacktest).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

the treatment of cancer, but the use of 67 Cu-labeled
drugs that selectively accumulate in cancer cells arethought to be more suitable for cancer therapy.
References
1) Y. Fujisawa et al., RIKEN Accel. Prog. Rep. 53, 175(2019).
2) G. A. Wiseman et al., Eur. J. Nucl. Med. 27, 766 (2000).
3) Y. Fujisawa et al., RIKEN Accel. Prog. Rep. 55, 141(2021).
4) C. Qin et al., J. Nucl. Med. 55, 812 (2014).
5) Y. Sugo et al., J. Phys. Soc. Jpn. 86, 023201 (2017).

2- 157 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Accelerator-based synthesis of rhenium-186 that enables high spatial
resolution imaging
S. Takeda,∗1 I. O. Umeda,∗1 M. Katsuragawa,∗1 A. Yagishita,∗1 A. Nambu,∗2 X. Yin,∗2 H. Haba,∗2 and
T. Takahashi∗1
Radiotheranostics is the integration of targetedradionuclide therapy with molecular imaging techniques such as Positron Emission Tomography (PET)and Single Photon Emission Computed Tomography(SPECT). The exponential growth of radiotheranostics in the ﬁeld of oncology is due to its unique mechanism of action, which allows for the targeted elimination of tumor cells with minimal adverse eﬀects. The
radionuclides, used for diagnosis, emit β + particles in
PET and γ rays in SPECT. In contrast, for cancer
therapy, radionuclides that emit energetic α, β − , andauger electron particles are utilized.
Rhenium radioactive isotopes are an attractive option for radiotheranostics, as they emit both particles
suitable for targeted therapy and photons useful for
diagnosis, and can aid in developing radiopharmaceuticals. Rhenium belongs to the same chemical family
as technetium. Technetium-99m (99m Tc) is the mostwidely used radionuclide in nuclear medicine imaging, due to its short half-life and favorable physicalproperties such as low radiation exposure to patients.
Many 99m Tc-labeled probes have been developed andare used clinically to diagnose of various diseases. Mostof the ligands and chelation chemistry developed fortechnetium can be also applied to rhenium. 186 Re istypically produced through neutron irradiation in reactors in other countries, but production in Japan is challenging due to the diﬃculty of reactor production. Additionally, 186 Re produced in reactors includes a large
amount of carrier Re as raw material. At the RIKEN
RI Beam Factory, carrier-free 186 Re can be produced
through proton and heavy ion-induced reactions of186
W using the RIKEN AVF cyclotron. Our goal is
to develop new radiotheranostics using 186 Re.1,2)
186
Re emits gamma-rays at 137 keV, allowing visualization of biobehavior of 186 Re-labeled radiopharmaceuticals. However, the emission yield of 137 keV photons is as small as 9.4%. Therefore, high-sensitivity
and high-resolution imaging have been challenging
since the signals (137 keV photons) are prone to becontaminated by the continuum background constituted by scattering of high-energy gamma-rays causedby contamination of rhenium isotopes other than186
Re. In our previous experiment, 186 Re was produced in the 186 W(d, 2n)186 Re reaction using the24-MeV d beam. We found that the byproduct of184
Re signiﬁcantly contributed to the contamination∗1∗2

Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo
RIKEN Nishina Center- 158 -and caused signiﬁcant degradation in imaging quality.
To improve imaging quality, it is essential to increase
the radionuclidic purity of 186 Re. In this study, we produced 186 Re in the 186 W(p, n)186 Re reaction using the
14.8-MeV proton beam on target and successfully improved the radionuclidic purity of 186 Re from 94.43%
to 99.56%.
A 19-MeV proton beam delivered from the RIKEN
AVF cyclotron was degraded to 14.8 MeV through a Ta
plate (192.6 µm) and irradiated onto a 186 WO3 powder (isotope enrichment of 186 W: 99.79%; thickness:∼200 mg/cm2 ). After irradiation, 186 Re was puriﬁed
by chemical separation.3) 3 MBq of 186 Re in 200 µL
of 0.01 M HCl was shipped to National Cancer Center
Research Center for the imaging experiment.
We demonstrated the eﬀectiveness of the puriﬁcation for imaging using CdTe-DSD SPECT4) (Fig. 1)
developed by the IPMU team. CdTe-DSD SPECT isa novel small animal imaging system consisting of 8
modules of CdTe Double-sided Strip Detectors5) and amulti-pinhole collimator made of tungsten. The detector has an energy resolution of 1–2 keV (FWHM) in
10–100 keV and 1.6% (FWHM) at 140 keV, which isaround three times better than those of currently available high-grade semiconductor SPECT systems. An
ultra-high spatial resolution of better than 350 µm is
possible. Figure 2 compares phantom imaging resultsfor 186 Re with a purity of 94.43% (left) and 99.56%(right). The image was noisy for lower purity becauseof the continuum background produced by 184 Re. On
the other hand, the preferred image was obtained forhigh-purity 186 Re. This is a promising result, and wewill proceed to in-vivo imaging with mice.

Fig. 1. CdTe-DSD SPECT viewed from the entrance window for small animals.

Ⅲ-3. Radiochemistry & Nuclear Chemistry(A) 186Re purity: 94.43%

RIKEN Accel. Prog. Rep. 56 (2023)(B) 186Re purity: 99.56%
1.0
0.35

0.75
0.5

Fig. 2. The comparison of phantom imaging results for186
Re with a radionuclidic purity of 94.43% (left) and
99.56% (right) taken with CdTe-DSD SPECT.

References
1) I. O. Umeda et al., RIKEN Accel. Prog. Rep. 54, 157(2021).
2) I. O. Umeda et al., RIKEN Accel. Prog. Rep. 55, 139(2022).
3) N. Shigeta et al., J. Radioanal. Nucl. Chem. 205, 85(1996).
4) S. Takeda et al., IEEE Trans. Radiat. Plasma Med. Sci.
(to be submitted).
5) S. Takeda et al., Nucl. Instrum. Methods Phys. Res. A
912, 57 (2018).

2- 159 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

44m

Sc-DOTA-TATE imaging with a cancer disease mouse model for
multiple-isotope PET imaging

T. Fukuchi,∗1 Y. Kanayama,∗1 Y. Nakatani,∗1 A. Nambu,∗2 S. Usuda,∗2 Y. Shigekawa,∗2 X. Yin,∗2 H. Haba,∗2
and Y. Watanabe∗1
Positron emission tomography (PET) is a powerful tool for the visualization of radiotracer distribution
used for imaging diagnosis in medical and fundamental
life sciences. However, standard PET is only useful forsingle-tracer imaging because of the energy constancy
of annihilation photons, which are utilized for PET
imaging. To enhance the usefulness of PET, we developed a new PET system that can be used for simultaneous multi-tracer PET imaging, named multipleisotope PET (MI-PET).1,2)
A positron emitter 44m Sc is one of the MI-PET nuclides. MI-PET utilizes a prompt γ-ray to identify
the tracer nuclide in addition to coincidence measurement of positron-electron annihilation photons, which
is used for conventional PET systems. 44m Sc is a betaplus decay nuclide with a half-life of 58.6 h and emits
1157 keV prompt γ-ray successively after positronemission. As a preliminary study for future multitracer imaging, we conducted single-tracer PET imaging experiment using a cancer mouse model with 44m Sc
labelled drug.
For future multi-tracer imaging, we synthesized a
tracer labelled by an MI-PET nuclide 44m Sc (positron
prompt γ-ray emitter) and tested for accumulation
on cancer cells. For the experiment, we synthesized a 44m Sc labelled DOTA-TATE (DOTA-[Tyr3 ]octreotide), which is a compound containing tyrosine3 octreotate and somatostatin receptor for numerous
malignancies.
The labelling protocol was basedon a method developed by Huclier-Markai et al.3,4)
DOTA-TATE was purchased from BACHEM (Switzer44m
Sc was produced via the reaction ofland).
44
Ca(d, 2n)44m Sc with a 24-MeV deuteron beam at the
RIKEN AVF cyclotron and puriﬁed by ion-exchanges.
The produced 44m Sc was transported to the RIKEN
Kobe campus for the drug synthesis. A total of
0.2 nmol of DOTA-TATE and 5 MBq of 44m Sc wereadded into NaOH 95◦ C for 30 min with shaking. Afterincubation, 1.1 MBq of 95◦ C for 30 min with shaking.
After incubation, 1.1 MBq of 44m Sc labelled DOTATATE was puriﬁed using a C18 solidphase extraction
column. The labelling ratio for 44m Sc-DOTA-TATE
was approximately 30%.
We prepared an 8-week-old immunodeﬁcient male
mouse transplanting pancreatic tumoral cell (AR42J)5)
as a cancer disease animal model. For the imaging
experiment, 1.1 MBq of 44m Sc-DOTA-TATE was administered via the tail vein. After 1 min from admin∗1∗2

RIKEN Center for Biosystems Dynamics Research
RIKEN Nishina Center- 160 -

istration, a 90-min scan of the mouse abdomen was
performed under anaesthesia using the MI-PET system.1) The experimental setting for the mouse imaging is shown in Fig. 1. All animal experiments in thisstudy received ethical approval by the institutional review board of RIKEN and were performed in accordance with the guidelines for care and use of laboratory
animals.

Fig. 1. Experimental setting for the mouse imaging using
MI-PET system.

Figure 2 shows a photograph and reconstructed image of a mouse. In this reconstructed image, weFig. 2. A photograph (left) and reconstructed image (right)of a mouse administrated with 44m Sc-DOTA-TATE.
Image is reconstructed by conventional PET events,
namely coincidence measurement of the annihilation
photons without prompt γ-ray detection.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

can clearly observe the accumulation of 44m Sc-DOTATATE in AR42J cancer. In the future, we will perform imaging experiments for multi-drug comparisonon animal disease models using 44m Sc-DOTA-TATE
and other PET tracers, such as 18 F-FDG.
References
1) T. Fukuchi et al., Med. Phys. 40, 2257 (2017).
2) T. Fukuchi et al., J. Instrum. 16, P01035 (2021).
3) S. Huclier-Markai et al., Nucl. Med. Biol. 41, e36 (2014).
4) T. Fukuchi et al., RIKEN Accel. Prog. Rep. 55, 142(2022).
5) J. Christophe, Am. J. Physiol. 266, G963 (1994).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Source preparation technique for Ag211 At for alpha spectroscopy
S. Fujino,∗1 T. Kojima,∗2 K. Mori,∗1 T. Yamada,∗1,∗3 Y. Wang,∗4 X. Yin,∗4 and H. Haba∗4
211

At has attracted a considerable amount of interest
because of its potential advantages in targeted alphatherapy. High-resolution alpha spectrometry is one of
the most important techniques in radiochemical analyses and precise radioactivity measurements. Electroplating is widely used as a conventional technique toprepare α sources. However, there are several diﬃculties in applying this method to the measurement of211
At such as its short half-life and high volatility. To
overcome such diﬃculties, we studied another practical
approach using a Ag plate without electroplating.
In this study, carrier-free 211 At was producedby the 209 Bi(α, 2n)211 At reaction using the RIKEN
AVF cyclotron.1) Three diﬀerent chemical forms of
100 kBq/mL of 211 At solutions were prepared as listed
in Table 1. To reduce the radioactivity loss due to thevolatility of At, ascorbic acid (AA) was added to solution (II) considering the result of a previous study on
At retention using AA by Toyoshima et al.2) At is also
expected to have stable alkalinity; thus, NaOH wasadded to solution (III). Ag plates with a thickness of
0.1 mm were used to ﬁx 211 At. Approximately 30 µL
of each 211 At solution in Table 1 was directly dropped
onto a Ag plate. Sources were dried in a desiccatorwith silica gel. After drying process, sources were measured using a ZnS (Ag) scintillation detector with a 2π
geometry to evaluate the deposition yield of 211 At on
silver. A Si detector was also used to obtain an α
spectrum from each source with the deﬁned sourcesdetector geometry in vacuum. In addition, imaging
plate (IP) was used to conﬁrm the distribution of radioactivity in an active area on the Ag plate with 211 At
solution (I).
Table 1. 211 At solutions used in the present study.

At solutions

Chemical form

(Ⅰ)

211At

211

At in H2O

(Ⅱ)

211At+AA

211

At in 1 µg/mL AA aqueous solution(Ⅲ)

211At+NaOH

At in 50 µg/mL NaOH aqueous
solution211

3.E+07

Figure 1 shows the measured α spectra obtained bythree diﬀerent types of sources. Two major peaks of
211
At (Eα = 5.87 MeV) and 211 Po (Eα = 7.45 MeV)
∗1
∗2
∗3
∗4

were observed in each spectrum. As shown in Fig. 1,
the 211 Po peaks obtained by source (II) shifted to thelower energy side by approximately 20 keV comparedto those for source (I). This could be due to selfabsorption caused by AA. However, the full width at
half maximum (FWHM) of the 211 At peak of source(II) increased by only 4 keV compared with that forsource (I); thus, it could not cause a large uncertainty
in the activity measurement. In contrast, a signiﬁcantdegradation in the spectrum was observed for source(III) compared with the two other sources. The deposition yield of each 211 At source was determined as aratio of the 2πα count rate to the activity of 211 At.
The resulting deposition yields were 88.3% ± 1.2%,
98.4% ± 1.3%, and 40.3% ± 6.8% for sources (I), (II),and (III), respectively, indicating that AA contributes
to the retention of 211 At during drying. However, theresults obtained for source (III) may be aﬀected by
self-absorption, resulting in underestimation of the deposition yield.
Figure 2 shows the distribution of 211 At on a Ag
plate for 211 At solution (I) with an IP. Although the

Graduate School of Science and Engineering, Kindai University
School of Science and Engineering, Kindai University
Atomic Energy Research Institute, Kindai University
RIKEN Nishina Center- 162 -PSL intensity

211

Fig. 1. Measured α spectra obtained by 211 At sources.

2.E+0725

1.E+0717
90.E+00

1

9

17

25

1

Pixel Number (30 pixels (=6 mm) in height and width)

Fig. 2. Distribution of 211 At on a Ag plate.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

diameter of the 211 At solution drop before drying wasaround 6 mm, 99% of the radioactivity of the source
was concentrated within a diameter of 2 mm. In themeasurements with a deﬁned solid angle, an extensionof the active area might increase the uncertainty inthe evaluation of the geometric eﬃciency. Therefore,a source with a small active area, such as that prepared in the present study, could have the advantagethat the activity could be determined with a smaller
uncertainty.
References
1) Y. Wang et al., RIKEN Accel. Prog. Rep. 53, 192(2019).
2) A. Toyoshima et al., Radiat. Saf. Manage. 18, 13 (2019).

2- 163 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Radioactivity calibrations of 225 Ac and 211 At
K. Arai,∗1 M. Imamura,∗1 D. Mori,∗1 H. Ishizu,∗1 Y. Sato,∗2 H. Haba,∗3 X. Yin,∗3 Y. Wang,∗3 and Y. Wakitani∗1
225

Ac and 211 At are short half-life α-emitters thathave attracted attention as radiopharmaceuticals. The
minimum requirements for radiopharmaceuticals, the radioactivity of most preparations is speciﬁed as 90–110%.
To conﬁrm of fulﬁll the speciﬁcation, the calibration of
measuring instruments, and thus standard sources withsmall uncertainties to the best extent possible is essential. However, certain issues plague the radioactivity
calibration. First, 213 Po, which is one of the progenies
of 225 Ac, interferes with the measurement. The shorthalf-life of 3.70 µs1) of 213 Po causes counting loss owing to the β-rays emitted from its parent 213 Bi whenmeasured using a commercial liquid scintillation counter(LSC) with dead time of a few µs. Thus, a correction for
counting eﬃciency is necessary. Second, 211 At is highly
volatile; however, there is minimal knowledge on suitablesamples for the LSC measurement. In addition, 207 Bi,
which is one of the progenies of 211 At, is not in radiativeequilibrium; thus, the contribution of 207 Bi and its uncertainty on the calibration must be evaluated. In thisstudy, our radioactivity calibration methods for 225 Ac
and 211 At were examined to solve the above problems
through comparisons with the results obtained from the
National Institute of Advanced Industrial Science andTechnology (AIST).
The commercial LSC, Tricarb 4810TR (PerkinelmerInc.) and the custom-build LSC with variable dead time,
LSC0001 were used in the radioactivity measurementsof 225 Ac and 211 At. To correct for the counting loss of
213
Po in an 225 Ac solution, the dead time of LSC0001
was set to 100 µs, and a correction factor was calculated
from the ratio of the count rate measured by LSC0001
to that measured by 4810TR. The radioactivity was calculated by the CIEMAT-NIST method2) for both Japan
Radioisotope Association (JRIA) and AIST.
211
At was produced in the 209 Bi(α, 2n)211 At reaction at the RIKEN AVF cyclotoron.3) 211 At was dissolved with 1.2% ascorbic acid in 5/15 M phosphatebuﬀer or 1 M sodium hydroxide aqueous solution;4,5)
the sodium hydroxide solution was selected to suppress
loss of volatile 211 At. The contribution of 207 Bi to themeasurement at 24 h after distillation was estimated tobe approximately 0.1%. Therefore, measurements were
performed using Tricarb 4810TR within 2 half-lives after dry distillation to minimize the contribution of 207 Bi
as low as possible. After 211 At had decayed suﬃciently(above 10 days), the contribution of 207 Bi was evaluatedthrough re-measurements. The radioactivity of 211 At
was also calculated by the CIEMAT-NIST method.2)
The radioactivities of 225 Ac and 211 At were measured
∗1
∗2
∗3

R&D Section, Japan Radioisotope Association
National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology
RIKEN Nishina Center

to be 318.9 ± 4.6 kBq/g (k = 2) and 3.155 ± 0.064 kBq/g(k = 2), respectively, and they are shown in Fig. 1.
Most of the uncertainty components were uncertainties
in the calculations by the CIEMAT-NIST method. In
addition, the radioactivities of 225 Ac and 211 At by AIST
were 317.1 ± 4.8 kBq/g (k = 2) and 3.143 ± 0.025 kBq/g(k = 2), respectively, and both were consistent with ourdata within the uncertainty range.

Fig. 1. Intercomparison result of (A) 225 Ac and (B) 211 At
radioactivity.

In summary, the radioactivities of 225 Ac and 211 At
were measured and compared with those by AIST. Consistent results were obtained for both nuclides. JRIA
is an accredited calibration laboratory related radiation
and radioactivity in Japan Calibration Service System(JCSS). Accredited calibration laboratories, which satisfy the requirements of the measurement act can issue
calibration certiﬁcate with the “JCSS” logo. Furthermore, we are ready to calibrate 225 Ac radioactivity for
JCSS calibration. In the future, where 211 At is scheduled to applied for JCSS calibration nuclide and is already available for a general calibration.
References
1) M. -M. Bé et al., Table of Radionuclides (Bureau International des Poids et Mesures, Sèvres, 2010), Vol. 5, p. 59.
2) A. G. Malonda, Free Parameter Models in Liquid Scintillation Counting (Centro de Investigaciones Energéticas,
Medioambientales y Tecnológicas, Madrid, 1999).
3) Y. Wang et al., RIKEN Accel. Prog. Rep. 53, 192 (2019).
4) A. Toyoshima and A. Shinohara., Radioisotopes 67, 461(2018).
5) T. Watabe et al., J. Nucl. Med. 60, 1301 (2019).

- 164 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Activation cross sections of 28 Mg via α-particle-induced reaction on
27
Al
M. Aikawa,∗1,∗2 H. Huang,∗3,∗2 G. Damdinsuren,∗3,∗2 S. Ebata,∗4,∗2 H. Haba,∗2 S. Takács,∗5,∗2 F. Ditrói,∗5,∗2
and Z. Szücs∗5,∗2

∗1
∗2
∗3
∗4
∗5

mended values, the incident beam energy and thickness
of Al target foils were corrected within their uncertainties by +0.2 MeV and −1%, respectively. The othermeasured parameters were adopted without correction.
The corrected cross sections were consistent with therecommended values, indicating proper beam parameters and energy loss determination within the stack,as shown in Fig. 1.
The cross sections of the 27 Al(α, 3p)28 Mg reaction
were determined using the γ line at 1342 keV (Iγ =54%), which was emitted with the decay of 28 Mg (T1/2= 20.9 h). Figure 2 shows our preliminary result withthe earlier experimental data obtained from the EXFOR library2) and the TENDL-2021 theoretical values.6) The theoretical values are considerably lower
than the experimental data.
700

natTi(α,x)51Cr

Cross section (mb)

600

Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Graduate School of Science and Engineering, Saitama University
Institute for Nuclear Research (ATOMKI)- 165 -

500

IAEA (2018)
This work

400
300
200
100
0

0

10

20

30

40

50

α-particle energy (MeV)

Fig. 1. Cross sections of the nat Ti(α, x)51 Cr monitor reaction with the IAEA recommended values.5)

0.5
Cross section (mb)Magnesium-28 (T1/2 = 20.9 h) decays with emission of a β − particle and γ rays. This radionuclide can be used as a radiotracer in several applications.1) The promising production reaction of 28 Mg
is the α-particle-induced reaction on 27 Al targets.
Ten experimental studies on the cross sections of the27
Al(α, 3p)28 Mg reaction were found in the EXFOR
library.2) However, the cross sections of the previous
studies are broadly scattered. Therefore, we performed
an experiment to obtain reliable cross sections of the27
Al(α, 3p)28 Mg reaction.
An experiment using a 50.7-MeV α-particle beam
was conducted at the RIKEN AVF cyclotron employing the stacked-foil activation technique and highresolution γ-ray spectrometry.
Pure metallic foils of 27 Al (>99% purity, 50 and
5 µm thick) and nat Ti (99.6% purity, 5 µm thick) werepurchased from Nilaco Corp., Japan. The 50- and 5µm Al foils were used as target and catcher foils, respectively. The Ti foil was used for the nat Ti(α, x)51 Cr
monitor reaction. The size and weight of all foils were
measured for the average thicknesses. The thicknessesof the Al target, Al catcher, and Ti monitor foils were
determined as 13.2, 1.22, and 2.37 mg/cm2 , respectively. The foils were cut into a 10 × 10 mm size andstacked in a target holder that served as a Faradaycup.
The stacked target was irradiated for 30 min witha 50.7-MeV α-particle beam. The initial beam energy
was determined using the time-of-ﬂight method.3) The
average beam intensity measured using the Faraday
cup was obtained as 205 nA. The beam energy degradation in the stacked target was calculated using stopping powers obtained from the SRIM code.4) γ rays
emitted from the irradiated foils were measured using ahigh-purity germanium detector (ORTEC GEM30P470) and dedicated analysis software (SEIKO EG&G
Gamma Studio) without chemical separation.
The cross sections of the nat Ti(α, x)51 Cr monitor reaction were derived using the γ line at 320 keV (Iγ =9.91%) from the decay of 51 Cr (T1/2 = 27.7 d). The
derived cross sections were compared with the International Atomic Energy Agency recommended values.5)
For best agreement between the measured and recom-

27Al(α,3p)28Mg

0.4

Nethaway (1958)
Martens (1970)
Nozaki (1975)
Probst (1976)
Rattan (1985)
Rattan (1986)
Karamyan (1992)
This work

0.3
0.2
0.1
0

25

30

35

40

45

50

α-particle energy (MeV)

Fig. 2. Measured cross sections of the 27 Al(α, 3p)28 Mg reaction with the literature data and the TENDL-2021
values.6)

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

References
1) N. P. van der Meulen et al., Appl. Radiat. Isot. 115,
125 (2016).
2) N. Otuka et al., Nucl. Data Sheets 120, 272 (2014).
3) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC2014), (2014), p. 3566.
4) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
5) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
6) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

2- 166 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production cross sections of 47 Sc via α-particle induced reactions onnatCa†
M. Aikawa,∗1,∗2 Y. Hanada,∗3,∗2 D. Ichinkhorloo,∗4,∗2 H. Haba,∗2 S. Takács,∗5,∗2 F. Ditrói,∗5,∗2 and Z. Szücs∗5,∗2

†
∗1
∗2
∗3
∗4
∗5

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 515, 1 (2022)
Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Nuclear Research Center, National University of Mongolia
Institute for Nuclear Research (ATOMKI)- 167 -

out chemical separation. The spectra of the nat Ca targets were measured with cooling times ranging from
3.2 h to 77 d.
The derived cross sections of the nat Ti(α, x)51 Cr
monitor reaction were compared with the IAEA recommended values4) to assess beam parameters and target thicknesses. The beam intensity and thicknessesof both AlH and AlL foils were corrected within theiruncertainties by +5.6% and −1%, respectively. The
measured thicknesses of the nat Ti monitor foil and the
CaF2 layer were adopted without any correction.
47
Sc could be produced directly in the 44 Ca(α, p)47 Sc
reaction and indirectly by decay of the co-produced47
Ca (T1/2 = 4.536 d) and 47 K (T1/2 = 17.50 s).
The indirect contribution was at a negligible level because 47 Ca and 47 K can be formed only on the lowerabundant 46 Ca and 48 Ca isotopes. The activity of 47 Sc
was determined by measuring the γ line at 159.381 keV(Iγ = 68.3%) from the decay of 47 Sc. The derived crosssections of the nat Ca(α, x)47 Sc reaction are shown in
Fig. 1 compared with the literature data2) and the theoretical values provided in the TENDL-2019 library.5)
The literature data on 44 Ca targets were normalized tothose on nat Ca targets. The newly obtained data correspond to a smooth excitation function, in contrast
to the literature data. The TENDL-2019 calculation
overestimates both the experimental datasets. Thus,
the data are expected to contribute to practical use innuclear medicine and aid in improving the theoreticalmodels.
6

natCa(α,x)47Sc

5

Cross section (mb)

Scandium-47 (T1/2 = 3.3492 d) is a potential radionuclide for therapy.1) Owing to the relatively smallabundance of 46 Ca (0.004%) and 48 Ca (0.187%) in natural calcium, its most possible production route forpractical use is expected to be the α-particle-induced
reaction on 44 Ca (2.086%).
In a literature survey, we found only one experimental study of the 44 Ca(α, p)47 Sc reaction.2) Therefore,
we performed an experiment to provide more credible cross sections of the nat Ca(α, x)47 Sc reaction. In
addition to the production cross sections of 47 Sc, theactivation cross sections for 46, 44m, 44g, 43 Sc and 47 Ca
were also determined simultaneously.
In the experiment, a 29-MeV α-particle beam wasused to activate the targets at the AVF cyclotron in
RIKEN. The stacked-foil activation technique and highresolution γ-ray spectrometry were adopted to performthe measurement.
Calcium-ﬂuoride (CaF2 ) was deposited on a highpurity 27 Al backing foil (AlH , 99.999% purity, Goodfellow Co. Ltd., UK) and used as the nat Ca target. Metallic foils of nat Ti (99.5% purity) for the nat Ti(α, x)51 Cr
monitor reaction and low-purity 27 Al (AlL , >99% purity) to catch recoiled products were purchased from
Nilaco Corp., Japan and inserted into the stack. The
average thicknesses of the AlH , AlL , and nat Ti foils
were 2.57, 1.50, and 2.30 mg/cm2 , respectively, determined from the measured lateral sizes and weights ofthe foils. The thickness of the deposited CaF2 layer
was 0.135 mg/cm2 , which was derived from the measured deposited area and net weight. All foils were cut
into a size of 10×10 mm to ﬁt a target holder that also
served as a Faraday cup. Each nat Ca target comprised
two CaF2 layers sandwiched between the AlH backing
foils. Twelve nat Ca targets were stacked with sevensets of nat Ti-AlL foils in the target holder.
The stacked target was irradiated with an α-particle
beam for 30 min. The measured average beam intensity and energy were 175 nA and 29.0 ± 0.2 MeV,
respectively. The energy degradation in the stacked
target was calculated using stopping powers obtained
from the SRIM code.3)
The high-resolution γ-ray spectrometry using ahigh-purity germanium detector was performed with-

Levkovski (1991) (44Ca)TENDL-2019
This work

4
3
2
1
0

0

5

10

15

20

25

30

α-particle energy (MeV)

Fig. 1. Measured cross sections of the nat Ca(α, x)47 Sc reaction with normalized literature data1) and TENDL2019 values.5)

This work was supported by the Japan-Hungary Research Cooperative Program between JSPS and HUS,
Grant number JPJSBP120193808 and NKM-43/2019.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

References
1) I. F. Chaple et al., J. Nucl. Med. 59, 1655 (2018).
2) 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, USSR, 1991).
3) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
4) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
5) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

2- 168 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production cross sections of 52g Mn in α-particle-induced reactions on
nat †V
G. Damdinsuren,∗1,∗2 M. Aikawa,∗1,∗2,∗3 Kh. Tegshjargal,∗4 N. Erdene,∗4 S. Ebata,∗5,∗2 and H. Haba∗2
Manganese-52 has the longer-lived ground state
Mn (T1/2 = 5.6 d, ε + β + : 100%) and the shorterlived excited state 52m Mn (T1/2 = 21.1 min, IT: 1.78%,
ε + β + : 98.22%). The decay processes of 52g Mn
are electron capture (70.6%) and positron emission(29.4%, ⟨Eβ + ⟩ = 242 keV).1) The positrons emitted
from the decay of 52g Mn can be used for Positron
Emission Tomography (PET).2) The direct routes to
produce 52g Mn involve charged-particle-induced reactions on chromium and vanadium. Whereas, the indirect route involves the internal transition of 52m Mn
co-produced simultaneously in the reactions. This
study, we focused on the α-particle-induced reaction
on nat V. Eleven experimental cross section data of
the nat V(α, x)52g Mn reactions were found in the EXFOR library.3) However, their data are largely scattered. Therefore, we measured the excitation functionof the nat V(α, x)52g Mn reaction up to 50 MeV. The obtained cross sections were compared with the literature
data and theoretical calculation in the TENDL-2019
library.4)
The stacked-foil activation technique and highresolution γ-ray spectrometry were used to measure
the cross sections. Pure metallic foils of nat V (25µm thick, 99% purity), nat Ti (5-µm thick, 99.6% purity), and 27 Al (5-µm thick, >99% purity) were purchased from Nilaco Corp., Japan, and used for the
stacked target. The nat Ti foils were interleaved for thenatTi(α, x)51 Cr monitor reaction. The 27 Al foils wereused to catch recoiled products from the nat V and nat Ti
foils. The average target thicknesses were derived fromthe measured size and weight of the original foils. Derived average thicknesses of nat V, nat Ti, and 27 Al foils
were 20.4, 2.24, and 1.22 mg/cm2 , respectively. The
original foils were cut into a size of 8 × 8 mm. Elevensets of V-Al-Ti-Ti-Al foils were stacked into a target
holder, which served as a Faraday cup.
The stacked target was irradiated with an α-particle
beam for 30 min. The primary beam energy was measured by the time-of-ﬂight method.5) The measured
beam energy was 50.6 ± 0.2 MeV. Consequently, theenergy degradation in the stacked target was calcu-

lated using stopping powers obtained from the SRIM
code.6) The average beam intensity measured using the
Faraday cup was 194 nA.
γ rays emitted from each irradiated foil were measured by a high-resolution HPGe detector (ORTEC
GEM-25185-P), which was calibrated with a multiple
gamma-ray emitting point source. The spectra wereanalyzed using dedicated software (SEIKO EG&G
Gamma Studio). Each nat V foil with the following
27
Al catcher foil was measured several times. The distance between the detector and foils was arranged toensure a dead time of less than 3%.
The cross sections of the nat Ti(α, x)51 Cr monitor reaction were derived and used to assess the beam parameters and target thicknesses. The measurement ofthe γ line at 320.08 keV (Iγ = 9.91%) from the decayof 51 Cr (T1/2 = 27.7025 d) was performed following a
cooling time of 3 days. Only the Ti foils at the beam
downstream of each Ti-Ti foil pair in the stack wereused for cross section deduction because the compensation of recoiled 51 Cr was expected. The dead time
during the measurements was maintained at less than
1%. Subsequently, the derived cross sections were compared with the IAEA-recommended values7) and foundto be consistent with each other. We adopted the measured beam parameters and target thicknesses without
any corrections for data analyses.
The cross sections of the nat V(α, x)52g Mn reaction
were derived. The γ line at 935.544 keV (Iγ = 94.5%)
from the decay of 52g Mn was measured following a cooling time of 17 d. During the cooling time, the excitedstate 52m Mn completely decayed to the ground state
52g
Mn or the stable nuclide 52 Cr. The cumulative cross

52g

†
∗1
∗2
∗3
∗4
∗5

400

natV(α,x)52gMn(cum)350

Cross section [mb]300

Condensed from the article in Appl. Radiat. Isot. 184,
110204 (2022)
Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
School of Engineering and Applied Sciences, National University of Mongolia
Graduate School of Science and Engineering, Saitama University- 169 -

◐

250
200
150
100
50
0

10

15

This work
Bowman (1969)
Dmitriev (1969)
Michel (1982)
Rama (1987)
Levkovski (1991)
Singh (1993)
Sonzogni (1993)
Ismail (1993)
Singh (1995)
Chowdhury (1995)
Bindu (1998)
TENDL-2019

20

25

◐
◐ ◐
30

◐

◐

◐

◐

◐

◐
35

40

45

50

Energy [MeV]Fig. 1. Excitation functions of the nat V(α, x)52g Mn reaction.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

sections could be derived from the measured net countsof the γ line. The excitation functions are shown in
Fig. 1 along with the literature data and TENDL2019 values.4) The measured cross sections exhibiteda smooth curve and agreement with part of the previous experimental data. However, the shape of the
TENDL-2019 values was largely diﬀerent from the experimental data.
G. Damdinsuren was granted a scholarship by the
M-JEED project (Mongolian-Japan Engineering Education Development Program, J11B16).
References
1) Y. Dong et al., Nucl. Data Sheets 128, 185 (2015).
2) F. Bianchi et al., Appl. Radiat. Isot. 166, 109329 (2020).
3) N. Otuka et al., Nucl. Data Sheets 120, 272 (2014).
4) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
5) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC 2014), (2014), p. 3566.
6) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
7) F. Tárkányi et al., IAEA-TECDOC-1211 (2007).

2- 170 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Activation cross sections of deuteron-induced reactions on nat Cr up
to 24 MeV†
H. Huang,∗1,∗2 M. Aikawa,∗1,∗2,∗3 Y. Hanada,∗1,∗2 and H. Haba∗2
Many radioisotopes are used for medical applications. 51 Cr (T1/2 = 27.8 d) decays through the electron
capture process with the emission of 320-keV γ rays.
The radionuclide is used to label red blood cells.1) Another medical radionuclide 52g Mn (T1/2 = 5.591 d),decays via the electron capture and positron emission
processes. The emitted positrons can be used for imaging of positron emission tomography (PET).2) Further,48
V (T1/2 = 15.97 d) can be used for tumor imaging.3)
Among the possible reactions to produce the medical
radionuclides, we focused on the deuteron-induced reaction on nat Cr. The reactions are also related to theeﬀects on the anti-corrosion coating of chromium andthe iron-chromium alloy in fusion reactors.4) Reliable
experimental and evaluated excitation functions of thereactions are required. Therefore, we aim to obtain a
new set of experimental data for the reactions up to
24 MeV.
We adopted the well-established stacked-foil activation technique and high-resolution γ-ray spectrometry.
The stacked target comprised foils of nickel-chromium(NiCr) alloy (99.9% purity, Goodfellow Co., Ltd., UK),nat
Ti (99.6% purity, Nilaco Corp., Japan), and 27 Al(>99% purity, Nilaco Corp., Japan). The nat Ti foil
was used for the nat Ti(d, x)48 V monitor reaction. 27 Al
foil was interleaved to collect recoiled products. The
average foil thicknesses were derived from their measured weight and size. We analyzed the elemental ratioof the NiCr alloy foil (Cr 21.5%, Ni 76.7%, Mn 1.7%)
by a scanning electron microscope with an energy dispersive X-ray spectrometer (Hitachi TM4000 Plus II).
The original foils were cut into squares of 8 × 8 mm
to ﬁt a target holder. Thirteen sets of NiCr-NiCr-AlTi-Ti-Al foils were stacked as the target. In addition,
the loss recoiled from the second foils was assumed tobe compensated by that from the ﬁrst foils. Only γ
spectra from each second foil were measured.
The stacked target was irradiated for 30 min using a 24-MeV deuteron beam at the AVF cyclotron
at RIKEN. The average intensity and primary energy of the beam were measured as 105 nA and 24.0
± 0.1 MeV, respectively. Energy degradation in thestacked target was calculated using stopping powers
obtained by the SRIM code.5)
The γ rays emitted from the foils were detected seven
†
∗1
∗2
∗3

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 530, 23 (2022)
Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University- 171 -

times using a high-purity germanium detector (ORTEC GEM30P4-70). To assess the radionuclides with
diﬀerent half-lives, the measurements were performed
with cooling times of 1 h–32 d, and the associated deadtime was less than 5.2%.
The cross sections of the nat Ti(d, x)48 V monitor
reaction were derived and compared with the recommended values of International Atomic Energy
Agency.6) According to the comparison, the beam intensity was decreased by 1.1% within the uncertainty(5%). The other parameters, such as primary beamenergy and target thicknesses, were adopted without
correction.
The production cross sections of 52g Mn were determined using the 935.544-keV γ line (Iγ = 94.5%), following a cooling time of 1.8 d. The short-lived isomer
52m
Mn (T1/2 = 21.1 min) decayed to 52g Mn via isomeric transition, with a branching ratio of 1.78%. Consequently, the derived cross sections were cumulative.
Our result was consistent with the recent studies whileslightly smaller than the others (Fig. 1). The predictedvalues in the TENDL-2019 library8) are larger than theexperimental data at the peak between 15–20 MeV.

Fig. 1. Cumulative cross sections of the nat Cr(d, x)52g Mnreaction compared with those in previous studies foundin the EXFOR library7) and the TENDL-2019 values.8)

References
1) S. J. Gray et al., J. Clin. Invest. 29, 1604 (1950).
2) M. Pagani et al., Eur. J. Nucl. Med. 24, 1301 (1997).
3) K. Iwai et al., Int. J. Rad. Appl. Instrum. B 16, 783(1989).
4) P. P. Liu et al., J. Nucl. Mater. 459, 81 (2015).
5) J. F. Ziegler et al., SRIM: the Stopping andRange of Ions in Matter (2008), http://www.srim.org .
6) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
7) N. Otuka et al., Nucl. Data Sheets 120, 272 (2014).
8) A. J. Koning et al., Nucl. Data Sheets 113, 2841 (2012).

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Activation cross sections of alpha-particle-induced reactions on
natural lanthanum up to 50 MeV†
S. Ebata,∗1,∗2 M. Aikawa,∗3,∗2 G. Damdinsuren,∗4,∗2 and H. Haba∗2

†
∗1
∗2
∗3
∗4

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 530, 18 (2022)
Department of Physics, Saitama University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Graduate School of Biomedical Science and Engineering,
Hokkaido University- 172 -

nium detector after cooling times of 7–28 h. The γline at 1575.85 keV (Iγ = 3.7%) with no interferencesfrom decay of 142g Pr was analyzed to derive the crosssections of the nat La(α, x)142 Pr reaction. The 142m Pr
isomer (T1/2 = 14.6 min) produced simultaneously inthe reaction decayed by IT decay mode to the groundstate during the cooling time. The cross-sections derived from the γ ray spectra were cumulative owing to
the contribution from the decay of its isomer.
The results of the experiments #1 and #2 are shownin Fig. 1 and compared with the previous studies2,3)
and the TENDL-2021 values.6) Data from our experiments were consistent with each other. However, ourcross-sections were slightly larger than the previous
data above 17 MeV. The TENDL curve underestimated all data above 17 MeV, its peak was locatedat slightly lower energy and its width was narrower
than those of all data.
200

160
Cross section ( mb )In the medical ﬁeld, radionuclides have been applied
to therapy and diagnosis for decades. Ensuring the accuracy of nuclear data is essential for the safe and eﬀective production of radionuclides. Recently, there havebeen investigations into radionuclides that can be used
for both therapy and diagnosis. The radionuclide 142 Pr(T1/2 = 19.12 h) is among the applicable candidates.1)
The alpha-particle-induced reaction on lanthanum isa practical method to generate 142 Pr. We found only
two experimental studies of the nat La(α, x)142g Pr reaction,2,3) for which the data are scattered and not fully
consistent (Fig. 1). Therefore, we measured the production cross-sections of the nat La(α, x)142 Pr reaction
using the activation method.
Two independent experiments were performed using
50 (#1) and 29 MeV (#2) α beams at the RIKEN
AVF cyclotron. To determine the excitation function, we applied the stacked-foil technique, and used ahigh-resolution germanium detector to measure the γrays from generated radionuclides. The stacked targets
comprised nat La (99% purity), 27 Al (>99% purity) andnat
Ti (99.6% purity) metal foils purchased from Nilaco
Corp., Japan. The actual thicknesses were derived as
15.4, 2.25, and 1.22 mg/cm2 for the nat La, nat Ti, and27
Al foils, respectively. The nat Ti foils were inserted
into the stack for the nat Ti(α, x)51 Cr monitor reaction to assess the beam parameters, energy loss of theparticles, and target thicknesses through comparisonsof the measured data with the recommended values.4)
The initial beam parameters were accepted; however,
the thicknesses of nat La foils were corrected by +2%
within the uncertainties (2%).
The 27 Al foils were used as catchers of recoiled products and for energy degradation. In experiment #1,
eighteen sets of La-Al-Ti-Ti, and in experiment #2,
eight La-Al-Ti foils were stacked into the target holders and served as Faraday cups. The energy degradation of the beam in the target was calculated using
stopping powers obtained from the SRIM code.5) Bothtargets were irradiated for 30 min. The average beam
intensities were 196 (#1) and 210 nA (#2), and themeasured primary beam energies were 50.6 (#1) and
29.0 MeV (#2).
The nat La foils with the following 27 Al catcher foil
were measured together using a high-purity germa-

nat

142g

La(α,n)PrTENDL-2021

Furukawa 1966

120

Verdieck 1967

This work #1
This work #2
80

40

0

10

15

20

25
30
35
Energy ( MeV )

40

45

50

Fig. 1. Cumulative cross-sections of the nat La(α, n)142g Pr
reaction in comparison with the previous data2,3) andthe TENDL-2021 curve (solid line).6)

In addition to 142 Pr, production cross-sections for
Pr and 141, 139g Ce were also obtained in thisstudy. Furthermore, data of 139g Ce and 138m Pr were
determined for the ﬁrst time.
139, 138m

References
1) M. Sadeghi et al., J. Radioanal. Nucl. Chem. 288, 937(2011).
2) M. Furukawa, Nucl. Phys. 77, 565 (1966).
3) E. V. Verdiegk et al., Phys. Rev. 153, 1253 (1967).
4) F. Tárkányi et al., IAEA-TECDOC-1211 (2007).
5) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
6) A. J. Koning et al., Nucl. Data. Sheets 155, 1 (2019).

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Reexamination of production cross sections of 153 Sm via α-particle
induced reactions on nat Nd†
M. Aikawa,∗1,∗2 M. Sakaguchi,∗3,∗2 N. Ukon,∗4,∗2 Y. Komori,∗2 H. Haba,∗2 N. Otuka,∗5,∗2 and S. Takács∗6,∗2

†
∗1
∗2
∗3
∗4
∗5
∗6

Condensed from the article in Appl. Radiat. Isot. 187, 110345(2022)
Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Advanced Clinical Research Center, Fukushima Medical University
Nuclear Data Section, International Atomic Energy Agency
Institute for Nuclear Research (ATOMKI)

nat

Nd foil was decreased by 2% and the initial beam energy was increased by 0.2 MeV. In addition, the beam
intensity of the second experiment (#2) was correctedby +2%.
The activation cross sections of 153 Sm were determinedusing the spectra measured after cooling times of 6.0–
19.5 h (#1) and 10.9–24.9 h (#2) when the parent 153 Pm(T1/2 = 5.25 min) had completely decayed to 153 Sm. The
net counts of the γ line at 103.18 keV (Iγ = 29.25%)
emitted from the decay of 153 Sm were measured. The
low energy γ rays were expected to be absorbed in thenat
Nd foil. The absorption probability of 2.1% was calculated using the target thickness and mass attenuationcoeﬃcients.8) The cumulative cross sections were thendetermined using the counts corrected for absorption.
The results are shown in Fig. 1 along with the experimental data published earlier3,4) and the TENDL-2021
values.7) The results obtained in this work are consistent with each other and also with our previous study.3)
In contrast, the other literature data4) are inconsistent.
The TENDL-2021 values are slightly deviated from ourdata, however, they support the smaller amplitude. The
experimental cross sections derived in this work can increase the reliability of the excitation function of thisreaction.
4

natNd(α,x)153Sm

3.5

Cross section (mb)Samarium radionuclides, 153 Sm (T1/2 = 46.3 h)
and 145 Sm (T1/2 = 340 d), can be used in nuclear
medicine.1,2) Among the possible production routes ofthese medical radionuclides, we studied the α-particleinduced reactions on nat Nd.3) However, the measured
cross sections of the nat Nd(α, x)153 Sm reaction were
found to largely deviate from the data studied in a previous study.4) The peak amplitude of the cross sections
was very diﬀerent in the two experiments. Therefore, we
performed two additional experiments to determine theactivation cross sections of the reactions with primary
focus on the peak amplitude of the nat Nd(α, x)153 Sm reaction.
Two experiments (#1 and #2) were conducted at the
RIKEN AVF cyclotron. Well-established methods for
activation cross section measurements were adopted, including the stacked-foil activation technique and highresolution γ-ray spectrometry.
The two stacked targets comprised pure metallic foils
of nat Nd (99% purity, Goodfellow Co., Ltd., UK) andnat
Ti (99.6% purity, Nilaco Corp., Japan). The nat Ti
foils were interleaved for the nat Ti(α, x)51 Cr monitor reaction to assess the incident beam parameters and target
thicknesses. The average thicknesses of the foils were derived from the measured size and weight of the originalnat
Nd and nat Ti foils. The derived thicknesses were 16.7
and 2.25 mg/cm2 , respectively. The foils were cut intoa size of 10 × 10 mm to ﬁt the target holders served as
Faraday cups.
Both targets were independently irradiated for 33 minwith α-particle beams. The measured incident beam energy of both beams was 28.9 MeV. The energy degradation of the beams in the stacked targets was calculated using the stopping powers obtained from the SRIM
code.5) The average beam intensities measured by the
Faraday cups were 103 nA (#1) and 104 nA (#2). The
γ rays emitted from the irradiated foils were measured
without chemical separation using high-purity germanium detectors.
Cross sections of the nat Ti(α, x)51 Cr monitor reaction
were used for ﬁnal assessment of the beam parameters
and target thicknesses. Based on the comparison withthe recommended values,6) the measured values were corrected within their uncertainties. The thickness of the

Qaim (2007)
Sakaguchi (2021)
TENDL-2021
This work (#1)
This work (#2)

3
2.5
2
1.5
1
0.5
0

0

10

20

30

40

50

α-particle energy (MeV)

Fig. 1. Cross sect ions of the nat Nd(α, x)153 Sm reactioreaction with previous experimental data data3,4) and the
TENDL TENDL-20 21 values.7)

References
1) I. G. Finlay et al., Lancet Oncol. 6, 392 (2005).
2) R. G. Fairchild et al., Phys. Med. Biol. 32, 847 (1987).
3) M. Sakaguchi et al., Appl. Radiat. Isot. 176, 109826(2021).
4) S. M. Qaim et al., Radiochim. Acta 95, 313 (2007).
5) J. F. Ziegler et al., SRIM: the Stopping and Range of Ionsin Matter (2008), http://www.srim.org/ .
6) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).
7) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
8) J. H. Hubble et al., X-Ray Mass Attenuation Coeﬃcients, NIST Standard Reference Database 126,
https://dx.doi.org/10.18434/T4D01F .

- 173 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Activation cross sections of 7 Li-induced reactions on nat Sm
M. Aikawa,∗1,∗2 G. Damdinsuren,∗3,∗2 S. Ebata,∗4,∗2 N. Ukon,∗5,∗2 and H. Haba∗2

∗1
∗2
∗3
∗4
∗5

Faculty of Science, Hokkaido University
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Graduate School of Science and Engineering, Saitama University
Advanced Clinical Research Center, Fukushima Medical University

ferences in the γ line were assessed. The ground state(T1/2 = 13.517 y) and excited state of 152 Eu (T1/2 =9.3116 h) emit the same energy γ rays in the decay. The
long-lived 152g Eu decayed less during the measurements.
The contribution from 152m Eu (Iγ = 2.4%) could be neglected because no peak of the more intense γ line (Iγ= 14.2%) was found. Another possible interference ofthe 344.90-keV γ line (Iγ = 2.12%) from 151 Pm (T1/2 =28.40 h) was negligibly small because the more intense γline at 340.08 keV (Iγ = 22.5%) was missing in the spectra. The count rate of the 344.3-keV γ peak decreased
with the half-life of 152 Tb, indicating less contribution
from other radionuclides.
The result is shown in Fig. 1. No previous study of thereaction was found. According to the threshold energies(Table 1), the ﬁrst peak at 40 MeV comprises reactions
on several Sm isotopes. Above 60 MeV, the reaction
on 154 Sm can be dominant. We will ﬁnish analyses todetermine the cross sections of 152 Tb and other Tb radionuclides.
140

natSm(7Li,x)152Tb

120

Cross section (mb)Terbium radionuclides can be used for nuclear
medicine.1) High speciﬁc activities of the Tb radionuclides can be obtained using charged-particle-induced
reactions on neighbor elements, such as Gd, Er and
Sm. We focused on 7 Li-induced reactions on Sm. We
found two experimental studies for fusion reactions on
144, 152
Sm enriched targets in a literature survey.2,3) The
data shortage of the experimental cross sections motivated us to experiment with 7 Li-induced reactions on
nat
Sm. Due to the isotopic ratio of nat Sm (144 Sm 3.08%,
147
Sm 15.00%, 148 Sm 11.25%, 149 Sm 13.82%, 150 Sm
7.37%, 152 Sm 26.74% and 154 Sm 22.74%), the reactions
can produce Tb radionuclides simultaneously.
The experiment using a 7 Li beam was conducted at
the RIKEN AVF cyclotron. We adopted well-establishedmethods, such as stacked-foil activation technique and γray spectrometry, to determine activation cross sections.
Two nat Sm (5-µm thick, 99% purity, Nilaco Corp.,
Japan) and one 27 Al (5-µm thick, >99% purity, Nilaco
Corp., Japan) foils were purchased for the stacked target. The size and weight of the foils were measured
to derive the average thicknesses. The measured thicknesses of the two nat Sm and 27 Al foils were 4.07, 4.20,
and 1.21 mg/cm2 , respectively. The foils were cut into asize of 10 × 10 mm. Nineteen sets of Sm-Sm-Al-Al foils
were stacked in a target holder that served as a Faraday
cup.
Irradiation with a 72-MeV 7 Li beam on the stacked
target lasted for 48 min. The incident beam energy wasmeasured using the time-of-ﬂight method. The beam energy degraded at each foil was calculated using the measured foil thicknesses and stopping powers retrieved fromthe SRIM code.4) The average beam intensity measured
using the Faraday cup was 48.9 nA.
The γ rays emitted from the irradiated foils were measured using a high-resolution HPGe detector (ORTEC
GMX30P4-70) and dedicated software (SEIKO EG&G
Gamma Studio). The γ-ray measurements of the nat Sm
foils were repeated ﬁve times with a cooling time of 1.1
h–2.7 d. The associated dead time was less than 2.2%.
The nuclear data required for the deduction of the crosssections were retrieved from NuDat 3.0.5)
The cross sections of the nat Sm(7 Li, x)152 Tb reaction were determined from net counts of the γ line at344.2785 keV (Iγ = 63.5%) emitted from the decay of152
Tb (T1/2 = 17.5 h). The spectra measured with thecooling time of 9.6–27.4 h were adopted. Possible inter-

This work

100
80
60
40
20
0

0

10

20

30

40

50

60

70

Energy (MeV)

Fig. 1. Measured cross sections of the nat Sm(7 Li, x)152 Tb reaction.
Table 1. Q value and threshold energy (E th ) of the reaction
on each Sm isotope target for 152 Tb production.

Reaction
Sm(7Li,2n)152Tb
Sm(7Li,3n)152Tb
149
Sm(7Li,4n)152Tb
150
Sm(7Li,5n)152Tb
152
Sm(7Li,7n)152Tb
154
Sm(7Li,9n)152Tb
147
148

Q value
(MeV)
−5.7
−13.9
−19.8
−27.7
−41.6
−55.4

Eth (MeV)
6.0
14.5
20.7
29.1
43.6
58.1

References
1) C. Müller et al., J. Nucl. Med. 53, 1952 (2012).
2) P. K. Rath et al., Phys. Rev. C 88, 044617 (2013).
3) M. S. Gautam et al., Int. J. Mod. Phys. E 29, 2050029(2020).
4) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res. B
268, 1818 (2010).
5) National Nuclear Data Center, The NuDat 3.0 database,
http://www.nndc.bnl.gov/nudat3/ .

- 174 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Activation cross sections of deuteron-induced reactions on natural
gadolinium up to 24 MeV†
D. Ichinkhorloo,∗1,∗2 M. Aikawa,∗1,∗3,∗4 Ts. Zolbadral,∗2,∗3,∗4 Y. Komori,∗3 and H. Haba∗3
Terbium (Tb) and gadolinium (Gd) radionuclides canbe used for medical applications. For example, 161 Tb(T1/2 = 6.89 d) can be used for targeted β − radionuclide
therapy.1) The production cross sections of the radionuclide are important nuclear data in terms of practical use.
The radionuclide can be produced via charged-particleinduced reactions on nat Gd, of which can yield the compositions as follows: 152 Gd (0.2%), 154 Gd (2.2%), 155 Gd(14.8%), 156 Gd (20.5%), 157 Gd (15.7%), 158 Gd (24.8%),
and 160 Gd (21.8%). In this study, we focused on the
deuteron-induced reactions on nat Gd. In the literature
survey, only two experimental studies of the cross sections were found.2,3) However, the experimental data
show a discrepancy between them. Therefore, we performed to measure cross sections of the deuteron-induced
reaction on nat Gd. The result was compared with the literature data2,3) and the TENDL-2021 values.4)
The experiment to determine the activation cross sections was conducted at the RIKEN AVF cyclotron. The
stacked-foil activation technique and the high-resolution
γ-ray spectrometry were adopted. The stacked target
comprised foils cut from nat Gd (0.025 × 50 × 100 mm,
99.9% purity, Nilaco Corp., Japan) and nat Ti foils(0.005×50×100 mm, 99.6% purity, Nilaco Corp., Japan).
The thicknesses of the nat Gd and nat Ti foils were derived
from the measured size and weight and found to be 25.3
and 2.34 mg/cm2 , respectively. nat Ti foils were used forthe nat Ti(d, x)48 V monitor reaction to assess the beam
parameters and target thicknesses. The foils were cut
into a size of 8 × 8 mm and stacked into a target holderthat served as a Faraday cup.
The stacked target was irradiated with a deuteronbeam for 60 min. The average beam intensity measured by the Faraday cup was 98.1 nA. The beam energy
measured by the time-of-ﬂight method5) was 24.1 MeV.
Further, the energy degradation in the stacked target
was calculated using the target thicknesses and stopping
powers derived from the SRIM code.6)
The γ rays emitted from each irradiated foil were
measured using a high-resolution HPGe detector (ORTEC GMX30P4-70) and the dedicated software (SEIKO
EG&G Gamma Studio). The spectra of each foil were
measured four times with diﬀerent cooling time and distance. The associated dead time was less than 6.3%.
Comparisons indicated that the beam intensity was corrected by +6.5% within its uncertainty (7%).
†
∗1
∗2
∗3
∗4

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B 536, 30 (2023)
Faculty of Science, Hokkaido University
Nuclear Research Center, National University of Mongolia
RIKEN Nishina Center
Graduate School of Biomedical Science and Engineering,
Hokkaido University

The cross sections of the nat Ti(d, x)48 V monitor reaction, beam energy and measured foil thicknesses wereadopted without any correction. The cross sections using the corrected parameters were consistent with therecommended values.
The cross sections of the nat Gd(d, x)161 Tb reaction
were derived using the γ line at 74.57 keV (Iγ = 10.2%).
The self-absorption of the low-energy γ line in each nat Gd
foil was estimated as 9.5%. The measurements were performed following a cooling time of 39–42 d. The coproduced parent 161 Gd (T1/2 = 3.66 min) decayed during the cooling time.
The cumulative cross sections are shown in Fig. 1 withthe literature data2,3) and the TENDL-2021 values.5)
Both experimental data were consistent our data below
12 MeV with deviations observed above 12 MeV. The
TENDL-2021 values were smaller than the experimental
data.

Fig. 1. Excitation function of the nat Gd(d, x)161 Tb reaction
with the previous data2,3) and the TENDL-2021 data.4)

In addition to 161 Tb, we also determined the production cross sections of 153, 154m1, 154m2, 155, 156, 160 Tb and153, 159
Gd. The cross sections are almost consistent withthe experimental data studied earlier. The results are expected to contribute to development of theoretical model
calculation and nuclear medicine.
References
1) C. Müller et al., J. Nucl. Med. 53, 1951 (2012).
2) F. Szelecsényi et al., J. Radioanal. Nucl. Chem. 307, 1877(2016).
3) F. Tárkányi et al., Appl. Radiat. Isot. 83, 25 (2014).
4) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
5) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC 2014) (2014), p. 3566.
6) J. F. Ziegler et al., SRIM: the Stopping and Range of Ionsin Matter, http://www.srim.org .
7) A. Hermanne et al., Nucl. Data Sheets. 148, 338 (2018).

- 175 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Production yields of 165 Er and 169 Yb via 24-MeV deuteron induced
reactionsY. Shigekawa,∗1 A. Nambu,∗1 Y. Kumakura,∗2 and H. Haba∗1
The use of Auger electrons for cancer therapy has
been widely investigated owing to their higher linear energy transfer than β − particles. 165 Er (T1/2= 10.4 h) and 169 Yb (T1/2 = 32.0 d), which decay
purely via electron capture (EC), are promising candidates for targeted radionuclide therapy using Auger
electrons.1,2) Moreover, the decay of 169 Yb accompanies the emission of cascade γ-rays potentially applicable to nuclear-medicine imaging that can prove
the local chemical environment.3) In order to perform
nuclear-medicine studies with 165 Er and 169 Yb, weneed to produce >1 GBq of 165 Er and >100 MBq
of 169 Yb and chemically purify them without adding
carriers. The production cross sections for these isotopes were reported for the 165 Ho(d, 2n)165 Er4,5) and169
Tm(d, 2n)169 Yb reactions.6–8) In this study, we conﬁrmed the production yields of 165 Er and 169 Yb via
24-MeV deuteron induced reactions using thick target
foils to determine the irradiation conditions to obtain
suﬃcient radioactivity for nuclear-medicine studies.
We irradiated 165 Ho and 169 Tm targets with a 23.9MeV deuteron beam at the RIKEN AVF cyclotron.
The 165 Ho target consisted of four 165 Ho foils (10 ×10 mm, 219.9 mg/cm2 , purity 99.9%) and was irradiated with an average beam intensity of 102 nA for
30 min. The 169 Tm target consisted of nine 169 Tm foils(8 × 8 mm, 94.5 mg/cm2 , purity 99%) and was irradiated with an average beam intensity of 105 nA for 3
h. After irradiation, γ-ray spectroscopy was performed
using high-purity Ge detectors.
The radioactivity of 169 Yb was determined with theγ peaks of 177.2 and 307.7 keV. For 165 Er, no-γ rays
are emitted; thus, the-X rays of Ho emitted after theEC decay were used to quantify 165 Er. The X-rays of
Ho (46.7, 47.5, 53.7, 53.9, and 55.3 keV) were observed
as three peaks in the γ-ray spectra. The peak corresponding to the 53.7- and 53.9-keV X-rays was useful to quantify 165 Er because the other X-rays overlap
with the Er X-rays emitted from 166 Ho (T1/2 = 26.8 h)
produced in the 165 Ho(d, p)166 Ho reaction. The countrate for the peak of the 53.7- and 53.9-keV X-rays was
obtained by ﬁtting a Gaussian function to each dataset.
The X-ray count rate as a function of the elapsed timedecreased with the half-life of 165 Er (10.4 h), meaningthat interference from radioactive impurities was negligibly small. To determine the radioactivity of 165 Er,
the self-absorption of X-rays by the thick Ho foils wascorrected using the γ-ray measurements for the twosides of each foil and a database of the X-ray absorp∗1∗2

RIKEN Nishina Center
Faculty of Medicine, Saitama Medical University- 176 -

tion coeﬃcients.9)
The cross sections of 165 Er and 169 Yb (Figs. 1 and
2) are almost consistent with those of previous studies.4–8) The total radioactivity of 165 Er at the endof bombardment (EOB) was 19.7(12) MBq, and theimpurity was 3.2(3) MBq of 166 Ho. The total radioactivity of 169 Yb at the EOB was 2.06(3) MBq,
and the impurities were 0.071(1) MBq of 168 Tm and0.16(3) MBq of 167 Tm. Hence, the thick target yields
for 165 Er and 169 Yb were determined to be 390(24)and 6.58(14) MBq/µAh, respectively. Via irradiation

Fig. 1. Excitation function of the 165 Ho(d, 2n)165 Er reaction measured in this work. The values measured inprevious studies4,5) are also shown for comparison.

Fig. 2. Excitation function of the 169 Tm(d, 2n)169 Yb reaction measured in this work. The values measured inprevious studies6–8) are also shown for comparison.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

with a 5-µA deuteron beam, we will be able to produce
1 GBq of 165 Ho in 0.5 h and 100 MBq of 169 Yb in 3 h,which are suﬃcient for nuclear-medicine studies.
References
1) I. D. Silva et al., Molecules 26, 7513 (2021).
2) S. M. Qaim et al., Radiochim. Acta 95, 313 (2007).
3) K. Shimazoe et al., Commun. Phys. 5, 24 (2022).
4) F. Tarkanyi et al., Nucl. Instrum. Methods Phys. Res.
B 266, 3529 (2008).
5) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 311, 102 (2013).
6) F. Tarkanyi et al., Appl. Radiat. Isot. 65, 663 (2007).
7) A. Hermanne et al., Nucl. Instrum. Methods Phys. Res.
B 267, 727 (2009).
8) M. Saito et al., Appl. Radiat. Isot. 125, 23 (2017).
9) M. J. Berger et al., XCOM: Photon Cross Section
Database (version 1.5), National Institute of Standards
and Technology, Gaithersburg, MD (2010).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Activation cross sections of α-particle-induced reactions on nat Ta
S. Takács,∗1,∗2 F. Ditrói,∗1,∗2 Z. Szücs,∗1,∗2 M. Aikawa,∗2,∗3,∗4 G. Damdinsuren,∗2,∗4 H. Haba,∗2 andS. Ebata∗2,∗5

∗1
∗2
∗3
∗4
∗5

Institute for Nuclear Research (ATOMKI)
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Graduate School of Science and Engineering, Saitama University- 178 -

pairs, as well as of the Ti monitor foils were measured by a high-resolution HPGe detector (ORTEC
GEM-25185-P) and analyzed using dedicated software(SEIKO EG&G Gamma Studio and Genie2000). The
spectra of each foil were measured several times to follow the decay of the reaction products. To maintaina low dead time the detector to foil distance was adjusted.
The cross-sections of the nat Ti(α, x)51 Cr monitor reaction were derived using the γ-line at 320.08 keV (Iγ= 9.910%) from the decay of 51 Cr (T1/2 = 27.7025d) and were compared with the recommended values of IAEA.4) Based on the comparison, the incident
beam energy was increased by 0.13% to 50.6 MeV,
and thickness of the nat Ta foil was reduced by 0.12%
to 14.36 mg/cm2 . Moreover, owing the escaping secondary electrons, the beam intensity was reduced by
3% to 197.2 nA. With these adopted changes, good
agreement was reached with the recommended values.
Activation cross-sections can be deduced for several
Re, W, Ta, Hf, and Lu reaction products. A preliminary result cross-section for the nat Ta(α, x)182g Re reaction is presented in Fig. 1 together with the previous experimental data and the TENDL-2021 values.1)
Data were assessed using the γ-line at 1427.3 keV (Iγ= 9.8%) emitted following the decay of 182g Re. Measurements were performed after a cooling time of 48
h. This gamma line can be considered as interference
free, because only decay of possible co-produced 176 Ta
may contribute above 38 MeV with a negligible, twoorders of magnitude lower intensity. The earlier experimental data were consistent in terms of position of the
maximum; however, certain diﬀerences exist in the am1500
nat

182g

Ta(,x)Re

This work
Scott 1968
Hermes 1974
Ismail 1988
Singh 1994
Tárkányi 2003
TENDL-2021

1200

Cross section (mb)

Tantalum is a frequently used material in accelerator technology exploiting its proper physical characteristics. However, by irradiating it with energetic alphaparticles several longlived radionuclides are produced.
To estimate the possible activity produced during anirradiation, knowledge of the excitation functions of
the possible reactions is required. In a literature survey, several experimental studies were found reporting
data on diﬀerent reactions. As signiﬁcant diﬀerence
exists in the peak position and amplitude among thediﬀerent datasets, we decided to perform an experiment to investigate the nat Ta(α, x) reactions and to
deduce more reliable cross-sections data of these reactions. Furthermore, the obtained results were compared with theoretical model prediction available in
TENDL-2021 data library.1)
The experiment was performed at the AVF cyclotronof RIKEN RI Beam Factory employing the stackedfoil target, activation method and high-resolution γray spectrometry. The target comprised pure metallic
foils of nat Ta (nominal thickness 9 µm, 99.99% purity,from Goodfellow, UK) and nat Ti (nominal thickness
5 µm, 99.6% from Nilaco Co., Japan). The nat Ti
foils served as catcher foils to stop and collect therecoiled reaction products and also as monitor foils
for the nat Ti(α, x)51 Cr monitor reaction. The average foil thickness was determined from the measured
lateral size and weight of the original foils. The derived thicknesses of nat Ta and nat Ti foils were 14.37
and 2.24 mg/cm2 , respectively. Subsequently, the original foils were cut into a size of 10×10 mm and stacked
into a target holder served as a Faraday cup to measure the incident beam intensity. Every Ta foil was
set together with a Ti catcher foil. The other Ti foils
were inserted into the stack at certain positions formonitoring, to obtain maximum information on the
beam parameters and the energy loss of the beam in
the target stack. The stacked target was irradiatedwith a 50.5 ± 0.2 MeV α-particle beam for 1 hour.
The primary beam energy was measured employing thetime-of-ﬂight method.2) Energy degradation in the target was calculated using stopping power data derived
from the SRIM code.3) The average beam intensity
measured on the Faraday cup was 203 nA.
The γ-ray spectra of the Ta and its Ti catcher foil

900

600

300

0
20

30

40

Particle energy (MEV)50

Fig. 1. Experimental cross-sections of the nat Ta(α, x)182g Re
reaction in comparison with TENDL-2021 values.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

plitude. The TENDL-2021 values disagreed with theexperimental data both in peak position and in amplitude. Preliminary results for the activation crosssections have already been deduced for several reactions; however, owing to the long half lives of several reaction products, the γ-ray spectrometry measurements
are still required and thus continued. Final results are
expected in the second half of the year 2023.
References
1) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
2) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC 2014), (2014), p. 3566.
3) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
4) A. Hermanne et al., Nucl. Data Sheets 148, 338 (2018).

2- 179 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Activation cross sections of deuteron-induced reactions on nat Re
M. Aikawa,∗1,∗2 Y. Toyoeda,∗3,∗2 G. Damdinsuren,∗4,∗2 S. Ebata,∗5,∗2 H. Haba,∗2 S. Takács,∗6,∗2 F. Ditrói,∗6,∗2
and Z. Szücs∗6,∗2
The ground states of 186 Re (T1/2 = 3.7186 d) andRe (T1/2 = 17.003 h) decay with the emission ofβ − particles and γ rays. Both rhenium radionuclides
can be used for theranostics, which combines therapy and diagnosis.1,2) The radionuclides can be produced through neutron-capture reactions on rhenium
and charged-particle-induced reactions on tungsten andrhenium targets. The possible production reactions
should be investigated for practical use. In this work, we
focused on the deuteron-induced reactions on rhenium.
In a literature survey, we found only two experimental
studies of cross sections3,4) and their data were largely
scattered. Therefore, we performed an experiment tomeasure the cross sections of the reactions.
In the experiment a 24-MeV deuteron beam deliveredfrom the RIKEN AVF cyclotron was used to irradiate
the stacked target. We adopted well-established methods, such as stacked-foil activation technique and oﬀ-line
high-resolution γ-ray spectrometry.
The stacked target consisted of thin and pure metallic
foils of nat Re (0.0125×50×50 mm, 99.98% purity, Goodfellow Co., Ltd., UK) and nat Ti (0.005 × 50 × 100 mm,
99.6% purity, Nilaco Corp., Japan). The nat Ti foils wereinterleaved for the nat Ti(d, x)48 V monitor reaction. The
lateral size and weight of each foil were measured. The
average thicknesses of the nat Re and nat Ti foils were
found to be 24.9 and 2.24 mg/cm2 , respectively. The
original foils were then cut into a size of 8 × 8 mm. Sixteen sets of Re-Re-Ti-Ti foils were stacked in a target
holder.
The target was irradiated with a 24-MeV deuteronbeam for 1 h. The initial beam energy was determinedby the time-of-ﬂight method. The average beam intensity determined using the charge collected by the Faraday cup was 105 nA. The beam energy at each foil was
calculated using stopping powers derived from the SRIM
code.5)γ-ray spectra of irradiated foils were measured using ahigh-purity germanium detector and dedicated software.
The associated dead time was less than 4.4%.
Cross sections of the nat Ti(d, x)48 V monitor reaction
were derived. The cross sections using the measured
beam parameters and target thicknesses agreed well with
the IAEA recommended values,6) as shown in Fig. 1.
The measured parameters were adopted without any correction to determine cross sections of the reaction on the

350

188

∗1
∗2
∗3
∗4
∗5
∗6

Faculty of Science, Hokkaido University
RIKEN Nishina Center
School of Science, Hokkaido University
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Graduate School of Science and Engineering, Saitama University
Institute for Nuclear Research (ATOMKI)

natTi(d,x)48V

Cross section (mb)

300
250

IAEA (2007)
This work

200
150
100
50
0

0

5

10

15

20

25

Projectile energy (MeV)

Fig. 1. Cross sections of the nat Ti(d, x)48 V monitor reaction
with the IAEA recommended values.7)

Re targets.
The cross sections of the nat Re(d, x)188g Re reaction
were determined using the γ line at 155.044 keV (Iγ =15.49%). The preliminary result is shown in Fig. 2 withthe literature data3,4) and the TENDL-2019 values.7)
The data of Natowitz et al.4) using 187 Re enriched targets were normalized to those using nat Re targets. The
normalized data are consistent with our result, while thedata by Ditroi et al.3) are higher. The TENDL-2019
values are lower than all experimental data.
natRe(d,x)188gRe

Cross section (mb)200

Natowitz (1967)
Ditroi (2013)
TENDL-2019
This work

150
100
50
0

0

5

10

15

20

25

Projectile energy (MeV)

Fig. 2. Measured cross sections of the nat Re(d, x)188g Re reaction with the literature data3,4) and the TENDL-2021
values.7) The literature data on enriched 187 Re4) werenormalized to those on nat Re.

References
1) A. M. Denis-Bacelar et al., Eur. J. Nucl. Med. Mol. Imaging 44, 620 (2017).
2) I. G. Finlay et al., Lancet Oncol. 6, 392 (2005).
3) F. Ditroi et al., Nucl. Instrum. Methods Phys. Res. B 296,
92 (2013).
4) J. B. Natowitz et al., Phys. Rev. 155, 1352 (1967).
5) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res. B
268, 1818 (2010).
6) F. Tárkányi et al., IAEA-TECDOC-1211 (2007).
7) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).

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Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production cross sections of 189g Ir in α-particle-induced reactions on
natRe
G. Damdinsuren,∗1,∗2 M. Aikawa,∗1,∗2,∗3 S. Ebata,∗4,∗2 H. Haba,∗2 S. Takács,∗5,∗2 F. Ditrói,∗5,∗2 andZ. Szücs∗5,∗2

∗1
∗2
∗3
∗4
∗5

Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Graduate School of Science and Engineering, Saitama University
Institute for Nuclear Research (ATOMKI)- 181 -

and analyzed using dedicated software (SEIKO EG&G
Gamma Studio). The spectra of each nat Re foil andthe following 27 Al catcher foil were measured several
times. The distance between the detector and the foils
was set to keep dead time below 1%.
To assess the beam parameters and target thicknesses, the nat Ti(α, x)51 Cr monitor reaction cross sections were derived. The γ line at 320.08 keV (Iγ =9.910%) from the decay of 51 Cr (T1/2 = 27.7025 d)
was measured after a cooling time of 2 d.
The derived cross sections were compared with the
IAEA-recommended values.8) Based on the comparison, the incident beam energy and thickness of thenat
Re foil were corrected within the uncertainties by+0.2 MeV and −1%, respectively.
The measurement of the γ line at 245.1 keV (Iγ =6.0%) emitted with the decay of 189g Ir was performed
after a cooling time of 36 d. The two short-lived
excited states with shorter half-lives (T1/2 = 13.3
and 3.7 ms, IT: 100%) decayed to 189g Ir during theirradiation. The cumulative cross sections of thenatRe(α, x)189g Ir reaction were derived from measured
net counts. The preliminary result of the cross sectionsof 189(g+m1+m2) Ir is shown in Fig. 1, together with theprevious experimental data2–4) and the TENDL-2021
values.5) The experimental data of Singh and Gadkari4) are higher than our data, while the peak position is located at nearly the same energy. The dataof Goncharov et al.2) and Ismail3) are largely diﬀerent
from ours in both peak amplitude and position. The
TENDL-2021 values agree well with ours.
800

Cross section [mb]Iridium-189 has the ground state 189g Ir (T1/2 = 13.2
d, ε: 100%) and two short-lived excited states 189m1 Ir
and 189m2 Ir (T1/2 = 13.3 and 3.7 ms, IT: 100%). The
radionuclide 189g Ir is an Auger electron emitter and canbe used for therapy in nuclear medicine.1) Chargedparticle-induced reactions on osmium and rhenium arepossible production routes of 189g Ir. In this work, we
focused on the α-particle-induced reactions on nat Re
targets. In a literature survey, three experimental
studies of the cross sections of the nat Re(α, x)189 Ir
reactions were found.2–4) The previous experimental
data are signiﬁcantly diﬀerent in peak position andamplitude. Therefore, we performed an experiment tomeasure reliable cross sections of the nat Re(α, x)189 Ir
reaction. The result was compared with the experimental data published earlier and the TENDL-2021
values.5)
The experiment was conducted at the AVF cyclotronof the RIKEN RI Beam Factory. The stacked-foil technique, activation method, and high-resolution γ-ray
spectrometry were used. The stacked target consistedof pure metallic foils of nat Re (12.5-µm thick, 99.99%
purity), nat Ti (5-µm thick, 99.6% purity), and 27 Al (5µm thick, 99.9% purity). All foils were purchased from
Nilaco Corp., Japan. The nat Ti foils were used for thenatTi(α, x)51 Cr monitor reaction. The 27 Al foils wereinserted to catch reaction products recoiled from thenat
Re and nat Ti foils. The target thicknesses were derived from the measured size and weight of the foils.
The derived thicknesses of nat Re, nat Ti, and 27 Al foils
were 25.3, 2.24, and 1.22 mg/cm2 , respectively. The
original foils were then cut into a size of 10 × 10 mm
to ﬁt in a target holder that served as a Faraday cup.
Fifteen sets of Re-Al-Ti-Al foils were stacked in thetarget holder.
The stacked target was irradiated with a 50.6 ±0.2 MeV α-particle beam for 30 min. The primary beam energy was measured by the time-of-ﬂight
method.6) Energy degradation in the stacked target
was calculated using stopping powers derived from the
SRIM code.7) The average beam intensity measured by
the Faraday cup was 203 nA.
The γ-ray spectra were measured using a highresolution HPGe detector (ORTEC GEM-25185-P)

700

natRe(α,x)189(g+m1+m2)Ir

600

Ismail (1993)
Singh (2004)
TENDL-2021
This work

500
400
300
200
100
0

0

10

20

30

40

50

Energy [MeV]Fig. 1. Cumulative cross sections of the nat Re(α, x)189g Ir
reaction.

The analyses to determine the ﬁnal cross sections of
Ir and other co-products are continued. The thick189g

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

target yields of the products can be calculated using
the measured cross sections. The ﬁnalized results are
expected to contribute to the practical use of radionuclides in nuclear medicine.
G. Damdinsuren was granted a scholarship by the
M-JEED project (Mongolian-Japan Engineering Education Development Program, J11B16).
References
1) D. Filosofov et al., Nucl. Med. Biol. 94, 1 (2021).
2) K. S. Goncharov et al., Sov. J. Nucl. Phys. 32, 319(1980).
3) M. Ismail, Pramana - J. Phys. 40, 227 (1993).
4) N. L. Singh et al., Can. J. Phys. 82, 227 (2004).
5) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
6) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC 2014), (2014), p. 3566.
7) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
8) F. Tárkányi et al., IAEA-TECDOC-1211 (2007).

2- 182 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production cross sections of 198g Au in proton-induced reactions on
natPt†
G. Damdinsuren,∗1,∗2 M. Aikawa,∗1,∗2,∗3 Kh. Tegshjargal,∗4 N. Erdene,∗4 N. Ukon,∗5,∗2 and H. Haba∗2Gold-198 has two long-lived states, the ground state
Au (T1/2 = 2.6941 d, β − : 100%) and the excitedstate 198m Au (T1/2 = 2.272 d, IT: 100%). The groundstate 198g Au can be used in nuclear medicine, suchas brachytherapy1) and nanoparticles.2) The neutron
capture reaction on the monoisotopic element 197 Au
in a reactor can produce a considerable amount of
198g
Au. However, this method yields only the low
speciﬁc activity of 198g Au owing to the diﬃculty encountered in separating 198g Au from the Au target.
The high speciﬁc activity 198g Au can be produced using charged-particle-induced reactions on platinum. In
this study, the proton-induced reactions on nat Pt targets were investigated. Moreover, the literature survey, only two experimental studies of cross sectionsof the nat Pt(p, x)198g Au reaction were found.3,4) The
literature data have large uncertainties and show discrepancy. Therefore, we conducted an experiment toprovide reliable cross sections of the nat Pt(p, x)198g Au
reaction. Thus, the results of this study were compared with the previous data and theoretical model
calculation in the TENDL-2019 library.5)
The stacked-foil activation technique and highresolution γ-ray spectrometry were used for cross section. Pure metallic foils of nat Pt (20-µm thick, 99.95%
purity) and nat Ti (5-µm thick, 99.6% purity) were purchased from Nilaco Corp., Japan. The stacked target was composed of nat Pt and nat Ti foils. The nat Ti
foils were used for the nat Ti(p, x)48 V monitor reaction
for assessment of the beam parameters and the target
thicknesses. Size and weight of the original foils were
measured and the average foil thicknesses were derived. The derived average thicknesses of the nat Pt andnat
Ti foils were 39.2, and 2.24 mg/cm2 , respectively.
Both original foils were cut into a size of 10 × 10 mm.
Twenty-ﬁve sets of Pt-Pt-Ti-Ti foils were stacked in atarget holder served as a Faraday cup.
The stacked target was irradiated with a protonbeam. The irradiation lasted for 30 min. The primarybeam energy measured by the time-of-ﬂight method6)
was 30.1 ± 0.1 MeV. Consequently, the beam energy ateach foil was calculated using stopping powers derived

from the SRIM code.7) The average beam intensity was
101 nA, which was derived from irradiation period andcharge collected by the Faraday cup.
γ rays emitted from irradiated foils were measured by a high-resolution HPGe detector (ORTEC
GEM-25185-P) and analyzed using dedicated software(SEIKO EG&G Gamma Studio). Only the second
foil of the same element pairs was measured because
products recoiled from the second foil were assumed
to be compensated from the ﬁrst foil. The dead timethroughout the measurement was less than 4.7%.
Cross sections of the nat Ti(p, x)48 V monitor reaction were derived using the γ line at 983.5 keV (Iγ =99.98%) from the decay of 48 V (T1/2 = 15.9735 d). The
derived cross sections were consistent with the IAEArecommended values.8) Thus, the measured beam parameters and target thicknesses were adopted without
corrections for deduction of cross sections.
The cross sections of the nat Pt(p, x)198g Au reaction
were determined using the measurement of the γ line
at 411.80205 keV (Iγ = 95.62%) from the decay of
198g
Au. The measurement was performed following
a cooling time of 13 d. The possible contribution
through decay of 198m Au (T1/2 = 2.272 d, IT: 100%)
was negligibly small because intense γ lines of 198m Au
could not be found in any spectra. Figure 1 shows thederived cross sections in comparison with the previous
experimental data3,4) and TENDL-2019 values.3) The
excitation function exhibited a smooth curve and wasconsistent with previous experimental data within theuncertainty; although certain data points of Tárkányi
et al.3) were deviated. The peak amplitude and position of the TENDL-2019 values were slightly diﬀerent from the experimental cross sections although thetrend was similar.

198g

∗1
∗2
∗3
∗4
∗5

Condensed from the article in Appl. Radiat. Isot. 192,
110621 (2023)
Graduate School of Biomedical Science and Engineering,
Hokkaido University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
School of Engineering and Applied Sciences, National University of Mongolia
Advanced Clinical Research Center, Fukushima Medical
University

natPt(p,x)198gAu

8
Cross section [mb]†10

- 183 -

Tarkanyi (2004)
Showaimy (2019)TENDL-2019
This work

6
4
2
0

0

5

10

15

20

25

30

Energy [MeV]Fig. 1. Excitation function of the nat Pt(p, x)198g Au reaction.

Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 56 (2023)

G. Damdinsuren was granted a scholarship by the
M-JEED project (Mongolian-Japan Engineering Education Development Program, J11B16). This work
was partially supported by JSPS KAKENHI Grant No.
22H04961.
References
1) M. Konishi et al., J. Radiat. Res. 62, 871 (2021).
2) R. Chakravarty et al., Nucl. Med. Biol. 72, 1 (2019).
3) F. Tárkányi et al., Radiochim. Acta 92, 223 (2004).
4) H. Showaimy et al., Radiat. Phys. Chem. 157, 97(2019).
5) A. J. Koning et al., Nucl. Data Sheets 155, 1 (2019).
6) T. Watanabe et al., Proc. 5th Int. Part. Accel. Conf.
(IPAC 2014), (2014), p.3566.
7) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).
8) F. Tárkányi et al., IAEA-TECDOC-1211 (2007).

2- 184 -

Ⅲ-3. Radiochemistry & Nuclear Chemistry
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Production cross sections of 211 Rn via 7 Li-induced reaction on 209 Bi
N. Ukon,∗1,∗2 K. Washiyama,∗1 M. Aikawa,∗3,∗2 G. Damdinsuren,∗4,∗2 S. Ebata,∗5,∗2 and H. Haba∗2

∗1
∗2
∗3
∗4
∗5

Advanced Clinical Research Center, Fukushima Medical University
RIKEN Nishina Center
Faculty of Science, Hokkaido University
Graduate School of Biomedical Science and Engineering,
Hokkaido University
Graduate School of Science and Engineering, Saitama University- 185 -

beams for 60, 57, and 20 min, respectively. The average
beam intensities measured using the Faraday cups were147 (#1), 147 (#2), and 142 nA (#3). The beam energy common in the three experiments was 71.9 MeV.
The energy degradation in the targets was calculatedusing stopping powers obtained from the SRIM code.5)
Target #3 was suﬃciently thick to stop the beam.
γ rays emitted from the irradiated foils and sheet
were measured using a high-purity germanium detector
with diﬀerent cooling times ranging from 1.0 h to 33 d.
The production cross sections of 211 Rn (T1/2 = 14.6h) were determined using the γ line at 674.1 keV(Iγ = 45.4%). The γ line overlapped with others at
672.82 keV (Iγ = 3.27%) from 209 At (T1/2 = 28.5 min)and 675.15 keV (Iγ = 6.8%) from 207 At (T1/2 = 1.80h). The measurements with cooling times of 1.4–2.3 dwere adopted to neglect the contributions of the γ lines
from the shorter-lived co-products.
The preliminary results with the previously studied
experimental data2–4) are shown in Fig. 1. The results
obtained from targets #1 and #2 are slightly scattered
but consistent. The peak amplitudes of the previously
studied experimental data are lower than those of thedata of this study.
1000

Cross section (mb)Astatine-211 possesses a half-life of 7.214 h and isa promising radionuclide for targeted α-particle therapy.1) 211 Rn (T1/2 = 14.6 h) is the longer-lived parent
nuclide of 211 At and is expected for a 211 Rn/211 At generator.2) One possible reaction to produce 211 Rn is Liinduced reactions on the mononuclidic element 209 Bi.
Thus, we focused on the 7 Li-induced reaction on 209 Bi.
Based on our survey, three experimental studies were
found, and their data were scattered.2–4) Therefore, we
conducted experiments on the 209 Bi(7 Li, 5n)211 Rn reaction to measure cross sections and thick target yield.
We conducted three experiments, i.e., two for excitation functions and one for the thick target yield, using
72-MeV 7 Li beams at the RIKEN AVF cyclotron. γ-ray
spectrometry was used to identify radioactive products.
The stacked-foil activation technique was employed tomeasure the excitation functions.
To measure the excitation functions (#1 and #2),
independent stacked targets were prepared. For thetargets, small pieces of Bi (purity: 99.999%) and three
Al foils (purity: >99%, thickness: 10, 18, and 5 µm,
size: 100 × 100 mm) were purchased from Nilaco Corp.,
Japan. The 10-µm and 18-µm Al foils were used asbacking foils for targets #1 and #2, respectively, andthe 5-µm Al foil was used to cover the deposited Bi
layer. The lateral size and weight of the Al foils were
measured, and their average thicknesses of the 10-, 18and 5-µm Al foils were 2.17, 4.79, and 1.21 mg/cm2 ,respectively. The Al backing foils were cut into a sizeof 25×25 mm for the vacuum evaporation method. The
Bi pieces were evaporated and deposited on a circulararea with a diameter of 20 mm of the Al backing foils.
The weight of the Al backing foils before and after thedeposit process were measured, and the thicknesses of
the Bi layers ranged from 5.46 to 10.9 mg/cm2 . The
Bi layers on the Al backing and cover foils were cut
into a size of 8 × 8 mm to ﬁt target holders served as
Faraday cups. Two stacked targets comprised 20 setsof Al(5 µm)/Bi/Al(10 µm) for target #1 and 16 sets ofAl(5 µm)/Bi/Al(18 µm) for target #2.
To measure the thick target yield (#3), a Bi sheet(purity: 99.999%, thick: 1 mm, size: 25×25 mm, Goodfellow Co., Ltd., UK) was used. The Bi sheet and 5-µm
Al cover foil were cut into a size of 10 × 10 mm to ﬁt
another target holder.
Targets #1, #2, and #3 were irradiated with the 7 Li

209Bi(7Li,5n)211Rn
Meyer (1980)
Dasgupta (2004)
Maeda (2020)
This work (#1)
This work (#2)

800
600
400
200
0

30

40

50

60

70

Energy (MeV)

Fig. 1. Measured cross sections of the 209 Bi(7 Li, 5n)211 Rn
reaction with the literature data.2–4)

Hereafter, we will determine the production cross sections of 211 Rn. The thick target yield will be calculatedusing the measured cross sections and compared withthe experimental result.
References
1) F. Guérard et al., Cancer Biother. Radiopharm. 28, 1(2013).
2) E. Maeda et al., J. Radioanal. Nucl. Chem. 323, 921(2020).
3) G. J. Meyer et al., Appl. Radiat. Isot. 31, 351 (1980).
4) M. Dasgupta et al., Phys. Rev. C 70, 024606 (2004).
5) J. F. Ziegler et al., Nucl. Instrum. Methods Phys. Res.
B 268, 1818 (2010).

4. Radiation Chemistry and Biology

Ⅲ-4. Radiation Chemistry & Biology
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Sample preparation for ion-beam irradiation for biologicalexperiments
Y. Hayashi∗1 and T. Abe∗1
RIKEN has developed a unique technology for mutation induction by using heavy-ion beams from particle accelerators at the RI Beam Factory (RIBF). At
relatively low doses, ion beams induced mutations at
a high rate without severely inhibiting growth. The
irradiation treatment given to the various plant materials is quick, lasting between a few seconds and a
few minutes, but is suﬃcient to induce mutation. By
using this method, RIKEN has already put 39 newvarieties on the market in Japan, the United States,
and the European Union since 2001.1,2) Furthermore,high-yielding rice, good growth wakame (Undaria pinnatiﬁda), lettuce with low browning, microalgae withhigh oil content, and larger rotifer were identiﬁed as
beneﬁcial mutants.
We have developed an automatic irradiation system
consisting of a range shifter and an automatic sample
changer to cope with numerous requests with various
biological samples such as dry seeds, wet seeds, callus,
cultured tissue materials, pollens, seedings, cuttings
etc.3) Biological samples are stored in sample containers. Typical sample containers include plant boxes forregenerated plants and seedlings, 35-, 60-, and 90 mmdiameter plastic petri dishes for cultured tissues andseeds, and square plastic boxes for cuttings. The sample containers containing biological samples are attached to unique frames that support each sample containers.4) Irregularly shaped samples placed in zipper
bags or hybri-bags are ﬁxed directly to the frame in linewith the irradiation position. For example, Arabidopsis seeds were placed in a hybri-bag and arranged in asingle layer by deaeration, then we found the most effective LET for mutation induction.5) A uniform dose
distribution is important for reproducible treatment
on biological materials using ions with stable LET.
The thickness of the sample is limited by the irradiation conditions. Therefore, it is necessary to place
the sample in the most suitable container and attach
Table 1.

Samples∗1

Containers
Petri dish, Plant box

Cuttings

Zipper bag, Square plastic box

LiquidFig. 1. Various samples set in the frame of automatic sample changer.
a: seed in the zipper bag, b: liquid sample in the hybribag, c: centrifuge tube ﬁxed in the cassette, d: micro
tube and PCR tube ﬁxed in the cassette.

Sample containers available in the frames of automatic sample changer.

Cultured tissues
Seeds

the container to the frame.
We built a new beam line, ‘WACAME,’ to increaseavailable nuclides with higher LETs and longer ranges.
The Ar-ion beams are accelerated by RRC and IRC
to 160 MeV/nucleon and sent to the E5 beam lines.
Ar-ion irradiation is now available in tubes, increasing the number of microbes and microalgae users. We
have created two types of cassettes for liquid culturesof microbes and microalgae (Fig. 1). One is for 15 mL
centrifuge tube, and the other is for 1.5 mL micro and200 µL PCR tubes. The ﬁrst one is also available forcuttings that do not ﬁt into square plastic boxes. The
second one is rubber lined to prevent slipping down oftubes. Samples are ﬁxed by springs to adapt various
size of samples in both cassettes. Holes were drilled in
the frame to check the sample’s center. Each cassettealso has a hole, and by aligning it with the hole in theframe, accurate placement in the irradiation position
was made possible. In addition, yellow stickers wereplaced on the plates so that the irradiation ﬁeld could
be seen. We will continue to develop new frames andcassettes that promote eﬃciency in irradiation experiments as a tailor-made mutagen treatment technology
to meet user requirements.

Petri dish, Zipper bag, Square plastic box, Hybri-bag
Centrifuge tube (15 ml), Micro tube (1.5-2 ml), 8 strips PCR tube*1, Hybri-bag*2*1: Use 6 strips in the middle and cut off the both ends.
*2: The thickness of sample for Fe-ion irradiation must be less than 2 mm.

RIKEN Nishina Center- 187 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)

References
1) T. Abe et al., in Ion beam radiation mutagenesis in
Plant Mutation Breeding and Biotechnology, (Oxfordshire UK, 2012), p. 99.
2) T. Abe et al., Nucl. Phys. News 25, 30 (2015).
3) H. Ryuto et al., J. Biomed. Nanotechnol. 2, 88 (2006).
4) H. Ryuto et al., Plant Biotechnol. 25, 119 (2008).
5) Y. Kazama et al., Plant Biotechnol. 25, 113 (2008).

2- 188 -

Ⅲ-4. Radiation Chemistry & Biology
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Identiﬁcation of causal site for an Arabidopsis C30-144-as3 mutant
A. D. Nagalla,∗1 S. Ohbu,∗1 K. Ishii,∗1,∗2 Y. Kazama,∗1,∗3 T. Hirano,∗1,∗4 and T. Abe∗1
Mutations are one of the crucial factors for natural selection and species evolution. They occur frequently innature. With the development of science and technology, we can create artiﬁcial mutagenesis and manually
search for desirable characters. Among those artiﬁcial
mutagenesis techniques, heavy-ion beam irradiation has
been established as a reliable approach in plant breeding.1) An important parameter for ion-beam mutagenesis can be identiﬁed as linear energy transfer (LET).
The LET implies the amount of energy deposited perunit length of a particle’s path (keV/µm). The C-ion irradiation (30 keV/µm) on Arabidopsis seeds has a highmutation frequency2) and results mainly in single nucleotide variants (SNVs), small indels (<100 bp), in the
responsible genes for mutant phenotypes. The numberof homozygous mutated genes per genome is approximately ﬁve, making it easy to identify the causative
gene.3)In this study, we irradiated Arabidopsis (Col-0) seeds
with 400 Gy C-ions (30 keV/µm). The resulting mutant plants were isolated, allowing further generations
to be selfed, and screened for interesting phenotypes.
The C30-144-as3 mutant was identiﬁed as later ﬂowering and round rosette leaves containing plant (Fig. 1).
After the whole genome sequencing, mutation calling
was conducted using the AMAP: A pipeline for wholegenome mutation detection.4) This analysis resulted inhomozygous SNVs, a large deletion, and intrachromosomal translocations (ITX) occurred in genic regions(Table 1). In order to identify the candidate gene, weFig. 1. Ion beam mutant C30-144-as3 shows later ﬂoweringand round rosette leaves containing plant (b) comparedto Col-0 plant (a) on 31 days after germination.
∗1
∗2
∗3
∗4

RIKEN Nishina Center
Department of Radiation Measurement and Dose Assessment, National Institute of Radiological Sciences
Faculty of Bioresources, Fukui Prefectural University
Faculty of Agriculture, University of Miyazaki

Table 1. Homozygous mutated genes found in C30-144-as3.

Chr.

Position

Type

Size

1

1308836013167752
19600910
1131686912608684
23056674
9981769318677

ITX

79.39Kb

Affectedgenes
AT1G06917

SNV
DEL

1bp
1.29Mb

AT2G47860
111 genes

SNV

1bp
1bp
1bp

AT3G62300
AT4G02280
AT4G16550

2
3
3
4
4

SNV
SNV

planned to perform a linkage analysis using a backcrossed (BC) population. The BC1 F2 population consists of 84 plants. Phenotype scoring referred to theperfect C30-144-as3 plant (M3 ) with later ﬂowering andround rosette leaves.
A total of 17 plants showed mutant phenotype. The
segregation of the F2 population ﬁtted the 3 : 1 segregation ratio (wild-type: mutant = 67 : 17, χ2 =1.02). Therefore, we hypothesize that this mutation wascaused by a recessive single gene. Linkage analysis was
performed for all the homozygous mutated genes using
17 F2 plants, which showed the mutated phenotype.
The AMAP pipeline revealed large deletion of approximately 1.29 Mb in M3 plants. This deletion has lost a
total of 111 genes, according to the Arabidopsis genome
browser. We used two primer pairs and Sanger sequencing of PCR products for genotyping experiments. Linkage analysis resulted in 16 homozygous plants linked
with the above large deletion (one of the plants among
17 plants resulted in non-reproducible linkage analysis
result, which could be due to contaminated DNA), indicating responsible gene might be included in the deleted
fragment. Because among the homozygous mutatedgenes, only the 1.29 Mb deletion showed the linkage.
Next, we checked the gene description of all 111 genes
and found a single gene responsible for regulating ﬂowering time and leaf shape. It’s the gene AT3G30260 andalready identiﬁed as AGAMOUS-LIKE 79 (AGL79 ).5)
The non-functional mutants were reported to show later
ﬂowering and round rosette leaves. Then we presumed
AGL79 gene was the causative gene for the C30-40 mutant.
References
1) T. Abe et al., Plant mutation breeding and biotechnology(Oxfordshire UK: CABI, 2012), p. 99.
2) Y. Kazama et al., Plant Biotechnol. 25, 113 (2008).
3) Y. Kazama et al., BMC Plant Biol. 11, 161 (2011).
4) K. Ishii et al., Genes Genet. Syst. 91, 229 (2016).
5) R. Gao et al., Front. Plant Sci. 8, 2226 (2018).

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Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Analysis of splicing patterns in Arabidopsis egy1-4 carrying
argon-induced mutations in the intron 3-exon 4 region
A. Sanjaya,∗1,∗2 Y. Fujii,∗1 M. Asano,∗1 T. Abe,∗3 Y. Kazama,∗2,∗3 and M. Fujiwara∗1,∗3
Eukaryotic gene expression involves the splicing of
precursor messenger RNAs before the translation. The
U2 spliceosome, a nuclear ribonucleoprotein complex,
is important in the process of splicing, and recognizes
certain conserved “canonical” sequences in introns, including a GU at the 5’ end, an adenine known as the“branchpoint” located 20–50 bases upstream of the 3’
end, and an AG at the 3’ end. Based on the mechanismof intron excision discovered, the intron 5’ splice andintron 3’ splice sites are referred to as the splice donorsite and the splice acceptor site, respectively. Splicing
begins at the 5’ splice site and involves the formation of
an intron lariat at the branchpoint as the cleaved 5’ endof the intron becomes attached to it. The excision of theintron lariat from the 3’ splice site then allows for the
ligation of the exons.
Mutations at such canonical intron sites typicallycause ineﬃcient and/or cryptic splicings.1) In Arabidopsis thaliana, mutations of the intron 3’ splice site, either“AG to AA” or “AG to GG,” are known to activate
only cryptic 3’ splice sites but not 5’ splice sites.1,2) A
3’ splice site mutation resulting in cryptic 5’ splice site
activation has never been reported.
In A. thaliana, the Ethylene-dependent Gravitro-pismdeﬁcient and Yellow-green 1 (EGY1 ) gene (AGI code:
At5g35220) encodes a chloroplast-targeted metalloprotease and is composed of 10 exons and 9 introns. During its functional analysis, an argon-ion-induced allele,egy1-4 (Ar-28-pg13) ), has been noted as it contains an
AG to AC transition at the 3’-end of intron 3, in addition to 4-bp substitutions and a 5-bp deletion in thedownstream exon 4.4) To determine whether these mutations in the intron 3-exon 4 junction region of egy1-4
aﬀect the splice site selection in EGY1, the total RNAs
were extracted from 2-week-old seedlings of wild-type
and egy1-4, and analyzed using RT-PCR with primers
binding to the EGY1 5’-untranslated region and exon
5. The ampliﬁed PCR products were ligated to a vector
and transformed into an E. coli DH5α strain. The resulting colonies were subsequently cultured for the propagation of plasmids, which were then Sanger-sequenced.
The sequence of EGY1 cDNAs around intron 3 was thencompared between the wild-type and egy1-4.
Only one splicing pattern of intron 3 was observed in
the wild-type by sequencing 30 clones (Fig. 1; Table 1).
However, among 58 cDNA clones of egy1-4 examined,
42 exhibited no splicing of intron 3 (unspliced pattern).
The rest exhibited distinct splicing patterns from thewild-type ones: 5 and 8 clones exhibited activation of
∗1
∗2
∗3

Graduate School of Science and Technology, Sophia University
Graduate School of Bioscience and Biotechnology, Fukui Prefectural University
RIKEN Nishina Center

Fig. 1. Schematic comparison of EGY1 transcript splicing
patterns between the wild-type and egy1-4. Sole splicing
pattern (wt) was observed in the wild-type. Cryptic 3’
splice sites were activated without (patterns 1 and 2) orwith (pattern 3) the activation of cryptic 5’ splice site inegy1-4. The nucleotide letters in red denote that they are
uniquely produced in egy1-4 by argon-ion-irradiation.3)

Table 1. RT-PCR and cloning analysis of intron 3 splicing
patterns in wild-type and egy1-4.

Plant
line
Wild
type
egy1-4Intron 3
splicing
patternwt

Total:(unspliced)
1
2
3
Total:

Number of
cDNA clones
sequenced
30
30
42
5
8
3
58

Relativefrequency
100 %
100 %
72.4 %
8.6 %
13.8 %
5.2 %100 %upstream and downstream cryptic 3’ splice sites, respectively. Moreover, a new splicing pattern, exhibiting activation of cryptic 5’ splice site alongside activation of
3’ splice site, was found in 3 clones (Fig. 1; Table 1).
As sole splicing patterns were observed in all the otherintrons for both wild-type and egy1-4 (unpublished results), the pale green phenotype of egy1-4 plants4) was
attributed to the expression of truncated forms of EGY1.
This is due to premature stop codons in the mutant exon
3 or exon 4 in any spliced/unspliced variants. Our ﬁnding demonstrates that mutations induced by heavy-ion
irradiation signiﬁcantly impact on the terminal phenotype of plant bodies via interference of splicing.
References
1) J. W. S. Brown, Plant J. 10, 771 (1996).
2) M. A. Schuler, in Splice Site Requirements and Switches
in Plants, edited by A. S. N. Reddy and M. Golovkin(Springer, Berlin, 2008), p. 39.
3) T. Hirano et al., Mutat. Res. 735, 19 (2012).
4) A. Sanjaya et al., Plants 10, 1254 (2021).

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Ⅲ-4. Radiation Chemistry & Biology
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Irradiation of seeds with C-ion and Ar-ion beams for Streptocarpus
mutagenesis to understand leaf meristem genetics
K. Nishii,∗1,∗2 M. Möller,∗1 N. Kelso,∗1 H. France,∗1 S. Barber,∗1 Y. Hayashi,∗3 K. Ishii,∗3 and T. Abe∗3
Streptocarpus Lindl. (Gesneriaceae) attract developmental biologists owing to their variable shoot/leaf
forms, which include caulescents with ordinary shootapical meristem (SAM) and acaulescent (unifoliates
and rosulates) lacking SAMs (e.g., Figs. 1a–c). Anisocotyly (Fig. 1b), the unequal cotyledon development
producing a macrocotyledon also marks this genus/
family.1) Streptocarpus rexii Lindl. is rosulate and has
been studied as a model to understand their unique
cotyledon and leaf development. Previous results haveshown relocated expression of SAM genes in their leaf
meristems.1) Thus, the genetic and functional shift ofmeristems from the shoot apex laterally to the leaf
might result in their unique acaulescent forms. This
work is important to understand plant meristems andtheir eﬀects on plant form. To date, a genetic map,transcriptome, and genome have been generated for
S. rexii,2) which are important resources to isolate theunderlying genetic loci. Here, we use forward genetics
utilizing heavy-ion mutagenesis to facilitate this aim.3)

transported to RIKEN (Wako, Japan). C-ion (12 C6+ )and Ar-ion (40 Ar17+ ) irradiations were conducted at
RIBF. The high linear energy transfer (LET) value ofC-ion was set to 30 keV µm−1 , and that of Ar-ion to
184 keV µm−1 . For C-ion, doses of 50, 100, 150, 200,
300 and 400 Gy, and for Ar-ion, 10, 20 and 50 Gy wereused, labelled C50, C100, C150, C200, C300, C400,
Ar10, Ar20, and Ar50, respectively. The lethal eﬀects
of the treatments were assessed as the germination rateand seedling growth. The seeds were sown in Petridishes on ﬁlter paper soaked with tap water and examined 2 and 3 weeks later. The growth of seedlings(the cotyledon size) was measured 7 weeks after sowing. The ﬂower phenotype was also observed for mutations in the M1 generation from 20–26 plants per treatment. To obtain larger M2 populations for screening,
M1 seeds of selected treatments were sown and cultivated. The vegetative phenotype was observed while
focusing on mutations in leaf initiation. Germination
was observed in all treatments; however, it was delayed in C400 and Ar50. The ﬁnal germination rate
was low only for Ar50 (Table 1). A strong suppressionof seedling growth was observed in C300, C400, andAr50, and all seedlings eventually died. Over 20% of
M1 plants of C150, C200, Ar10 and Ar20 showed ﬂower
mutations, such as split corollas and shift in symmetry(Figs. 1c–e).
Table 1. Eﬀects of heavy-ion irradiation on Streptocarpus
rexii.

Fig. 1. Images of Streptocarpus rexii wild type and heavyion irradiated mutants. a-b) S. rexii wild type. b)
Anisocotyly. c) Wild type ﬂower. d-e) C200 ﬂower
mutations. f) C200 qualiﬁer “JW” M1 plant showing
delayed leaf initiation phenotype.

Seeds of S. rexii (RBGE 20170766*A) cultivated in
the glasshouses at Royal Botanic Garden Edinburgh(RBGE) were harvested in October 2018, certiﬁed at
Science & Advice for Scottish Agriculture (SASA; Phytosanitary Certiﬁcate No. SG/SASA/2018/033), and
∗1
∗2
∗3

Royal Botanic Garden Edinburgh
The Research Institute for Integrated Science, Kanagawa
University
RIKEN Nishina Center- 191 -

Considering all results together, C150, C200, andAr20 were just below the lethal dosage, and showed
clear ﬂower mutations. Thus, they were selected forlarge scale mutant screening. More than 1000 M1
plants of C150, C200, and Ar20 were cultivated to obtain M2 seeds. The estimated fertility rates (in May

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)2021) were 62, 47, and 40% for C150, C200, and Ar20,
respectively. Five of C200 M1 plants, and 25 of Ar20
showed a delayed leaf initiation phenotype (Table 1;
Fig. 1f). M2 seeds of these were harvested from four
C200 and 12 Ar20 plants. Now, these mutant phenotypes were observed for mutant stability in following
generations.
References
1) K. Nishii et al., Dev. Genes Evol. 220, 25 (2010).
2) K. Nishii et al., Plant Direct 6, e388 (2022).
3) T. Abe et al., Nucl. Phys. News 25, 30 (2015).

2- 192 -

Ⅲ-4. Radiation Chemistry & Biology
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Comprehensive eﬀects of heavy-ion beam irradiation on sweet potato(Ipomoea batatas [L.] Lam.)†
H. Park,∗1 Y. Narasako,∗2 T. Abe,∗3 H. Kunitake,∗4 and T. Hirano∗3,∗4
Sweet potato is one of the most important food crops
and plays a critical role in food supply and safety
worldwide. Although the main feature of sweet potato
is the formation of tuberous roots, the detailed mechanisms of how tuberous root formation is controlled by
the factors are still unknown. Therefore, an advanced
strategy is required for the investigation of molecularfunctions. Heavy-ion beam has been applied for mutation breeding in various plants and genetic studies.1,2)
In this study, Ar- and C-ion beam irradiation was applied to in vitro cultured shoots of sweet potato, andmutant lines were established to screen the mutants on
tuberous root formation.
In vitro cultured shoots with an axillary bud of sweet
potato (Ipomoea batatas ‘Beniharuka’) were irradiatedwith 12 C6+ ions (LET; 30 keV µm−1 ) at absorbed
doses of 5.0, 10.0, and 20.0 Gy, or 40 Ar17+ ions (LET;
184 keV µm−1 ) at absorbed doses of 1.0, 2.5, and
5.0 Gy. The regenerated shoot was cut into nodes,
each with an axillary bud, after three months of culture. Three lines were separated from each irradiatedshoot. The irradiated lines were acclimatized in thegreenhouse and then cultivated in the ﬁeld.
The shoot formation was decreased at high-dose irradiation of both ion beams. Shoulder doses on theshoot formation curve were considered 10 Gy for the
C-ion beam and 2.5 Gy for the Ar-ion beam. We haveobtained 335 lines, which consist of 104 and 231 lines
derived from Ar- and C-ion irradiation, respectively.
After the acclimatization, 116 and 211 irradiated lines
survived and were used for the mutant screening in theﬁelds in 2020 and 2021, respectively. The irradiatedlines demonstrated a wide range of phenotype variations in the tuberous roots (Fig. 1). Generally, thetotal weight of the tuberous roots tends to decreasein the C- and Ar-ion irradiated lines. The high-yieldlines, with an increase of more than 180%, were derived from Ar-ion irradiation. Considerable inhibitionof tuberous root formation was observed in the lines
derived from C- and Ar-ion irradiation. It was indicated that heavy-ion beam mutagenesis is eﬀective inbroadening the range of the phenotypes corresponding to tuberous root formation. These mutant candidates are expected to enhance our understanding of
the mechanisms related to tuberous root formation.
References
1) T. Abe et al., Nucl. Phys. News 25, 30 (2015).
2) T. Hirano et al., Cytologia 87, 3 (2022).

Fig. 1. Frequency distribution of the relative total weight of tuberous roots in C- and Ar-ion irradiatedlines. The data represents the combined results for 2020 and 2021. The circle and bar represent themean (100) and range of ‘Beniharuka,’ respectively.
†
∗1
∗2
∗3
∗4

Condensed from the article in Plant Biotechnol. 39, 311(2022)
Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki
Kushima AoiFarm Co.
RIKEN Nishina Center
Faculty of Agriculture, University of Miyazaki- 193 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Growth inhibition of marine red alga Agardhiella subulata throughC-ion beam irradiation
K. Tsuneizumi,∗1 M. Yamada,∗1 M. Mogamiya,∗2 Y. Sato,∗2 and T. Abe∗1
In the Japanese way of life, seaweeds such as laver,kelp, wakame, and hijiki have a long history of use andare consumed in large quantities. Recently, seaweeds
have gained attention as materials for the productionof carrageenan, alginic acid, and agar,1) and their production has been increasing in Asia as an aquaculture marine resource rather than for food. Furthermore, seaweeds contain fucoidan, which has proven tobe eﬀective in hair growth promotion,2) immunostimulatory activities,3) and anti-aging.4) This information
has led to increasing attention to seaweeds as raw materials for functional materials.
Agardhiella subulata, commonly known as edible redalgae, has been discovered as a new material that produces fucoidan,5) and there is much interest in increasing the production of its active ingredients. Breedingnew cultivars with properties such as high yield, highenvironmental adaptability, and high concentrations ofconstituents with human health beneﬁts is desirable
for enhanced value. In this report, to determine theeﬀective conditions of the C-ion beam for red algae
mutagenesis, we calculated the growth in the area of
irradiated regenerating buds.
Small fragments of A. subulata were cultured withNORI SEED (Daiichi Seimo Co., Ltd.), a highly enriched culture solution. A culture medium was prepared using 160 µL of NORI SEED diluted with
300 mL of autoclaved sea water. Small fragments
developed into regenerating buds for three weeks ina stirred 300-mL marine ﬂask containing the culture medium. The ﬂask was placed at 25◦ C for a
12 hours photoperiod with a light intensity of 50 µmol
photons · m−2 s−1 , and the culture medium in the ﬂask
was replaced every week. The regenerating buds were
replaced into 5-mL tubes at each irradiation condition.
Heavy-ion-beam irradiation was performed using C(LET = 30 keV/µm) at 8 irradiation doses of 5, 10,
20, 40, 70, 100, 200, and 400 Gy generated at the
RIKEN RIBF.6) Four hours after irradiation, eight regenerating buds were inoculated into each 36-mm dishcontaining 3 mL of fresh culture medium for each irradiation condition. The dishes were placed at 25◦ C
for a 12 hours photoperiod with a light intensity of
50 µmol photons · m−2 s−1 , and 150 µL of the 20-foldconcentrated culture medium was added every 2–3 d.
The regenerating buds were photographed every few
days and the sizes of 8 reproducing individuals (n = 8)
were calculated using Image J software version 1.5.17)(Fig. 1).
∗1
∗2

RIKEN Nishina Center
Riken Food Co., Ltd.

- 194 -

Fig. 1. Correlation between increasing area of regenerating
buds and C-irradiation dose. A correlation chart using
the average values of increasing area was constructed
for the unirradiated control and irradiated regeneratingbuds. The vertical vars represent the standard errors.

An increase in the area representing the regenerating buds irradiated up to 20 Gy in the correlation chartindicates that they proliferate in the same way as unirradiated controls (Fig. 1). In contrast, the growth inhibition of the regenerating buds is observed in a dosedependent manner eﬀected by 40–400 Gy C-ion beams(Fig. 1). In future studies, we will carry out largescale screening under each irradiation condition, andthe optimum irradiation conditions will be determinedbased on the frequency of the appearances of the mutant lines.
References
1) Y. C. Liao et al., Bioengineered 12, 3787 (2021).
2) I. S. Moon et al., Hear. Res. 282, 236 (2011).
3) R. Li et al., Mar. Drugs 21, 18 (2023).
4) R. Zhang et al., Carbohydr. Polym. 15, 228 (2020).
5) C. Faggio et al., Nat. Prod. Res. 30, 2016 (2015).
6) T. Abe et al., in Plant Mutation Breeding and Biotechnology, edited by Q. Y. Shu et al. (CABI, Oxfordshire,2012), p. 99.
7) C. Schneider et al., Nat. Methods 9, 671 (2021).

Ⅲ-4. Radiation Chemistry & Biology
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Semi-automated high-throughput microbial DNA extraction protocol
for population-scale mutation analysis
Y. Nishimiya,∗1 N. Lei,∗1 and H. Ichida∗1
At RIKEN Nishina Center for Accelerator-Based
Science, one active area of research is the application of heavy-ion beams to mutation breeding, where
we utilise next-generation sequencing and the massively parallel supercomputer “HOKUSAI” to characterise irradiation-induced DNA damage and subsequent genetic mutations statistically. In recent years,
we have demonstrated the eﬃcacy thereof using various model organisms, eﬃcient identiﬁcation of mutations through whole-genome and exome sequencing in Nicotiana tabacum L., and the applicabilityof the redundant sequence elimination algorithm inanalysing data obtained from a complex genome suchas wheat. We accordingly developed a versatile andhigh-accuracy mutation-detection pipeline.
Historically, only indirect measurements such as thesurvival rate and albino emergence rate were available to estimate the mutation-induction eﬃciency approximately. Whole-genome sequencing (WGS), on
the other hand, enables one to count the exact number of mutations in each sample, which presents two
crucial advantages: (i) The smaller error margin enables a more sensitive diﬀerentiation of the mutationinduction eﬃciency. (ii) Signiﬁcantly fewer samples are
required to estimate the optimal experimental condition compared to conventional indirect methods.
Therefore, we began testing the WGS-based
mutation-induction optimisation methodology against
the survival-rate-based estimates using budding yeast
with a small genome size. However, investigating themultitude of irradiation conditions (ion type, linear energy transfer, and irradiation dose) and genetic backgrounds (wild type and DNA-repair deﬁcient mutants),
where all combinations thereof require several (at least10) samples, necessitates the simultaneous cultivationof cultures on a considerable scale whilst maintaining
the overall pace of execution to control for their timesensitive nature properly.
To overcome this challenge, we devised a series oftechniques to achieve eﬃciency based on the knowledge that 500 µL of culture per sample is suﬃcientfor DNA extraction and sequencing. This small volume requirement permits us to use 96 deep-well plateswith signiﬁcantly high density (a desktop incubator
can cultivate up to 384 samples) and higher ease ofmanipulation than conventional test tubes. Moreover, after centrifugation and a brief lysis procedure,
we can directly transfer them onto the automatedliquid-handling robot (OT-2, Opentrons) in a smooth
production-line-like manner. Eliminating the necessity∗1

RIKEN Nishina Center- 195 -

to pipette the liquid culture from one tube to anotherensures that the entire volume of the obtained culture
proceeds for DNA extraction, reducing human labourand risks of cross-contamination. The 96 deep-wellplates we tested can also be used for cryogenic storageof the liquid culture.
Hence, we tested the yeast DNA extraction throughthe automated procedure. Following trial and error, we
veriﬁed the robot’s reliability to automatically executea protocol consisting of (i) cell-wall digestion with Zymolyase, (ii) extraction of DNA using magnetic beads,and (iii) elution of the extracted DNA. Although thereagents must be carefully prepared in advance, weestimate that the combined use of 96 deep-well plate
cultivation and robot DNA extraction would requireas little human labour as approximately half an hourin all to prepare up to 192 DNA samples per day, incomparison with the 4.5 hours including active andstandby time required for the manual alternative. Figure 1 presents an example of concentrations in ng/µLof the DNA thereby extracted across the well plate.
From past trials, we know that 700 ng is adequate
for sequencing. Thus, when the ﬁnal elution volume
is speciﬁed as 100 µL, the minimum concentration of
7 ng/µL suﬃces.

Fig. 1. Example distribution of extracted DNA concentration in ng/µL on a grid corresponding to the 96 deepwell plate. The blue-red bi-colour scale represents theincreasing yield.

At the time of writing this manuscript, we had acquired approximately 700 distinct yeast DNA samples following irradiation with carbon, argon, and ironbeams, the WGS data of which are presently being
analysed. Our current objectives are to establish the
population-scale WGS-based mutation analysis protocol as a more eﬃcient and accurate method to advanceour understanding of heavy-ion beam-induced mutations, DNA repair mechanisms, and their applications
to mutation breeding technology, and to develop statistical models to eﬃciently learn about and infer fromthe newly acquired rich source of genomic data.

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Heavy-ion irradiation enhanced the post-transcriptional modiﬁcationof CtIP
M. Izumi,∗1 T. Tsukada,∗1 and T. Abe∗1
Among DNA damages caused by ionizing radiation,
DNA double strand breaks (DSBs) are the most lethal
as misrepaired or unrepaired DSBs can cause a lossof genetic information, canceration, and cell death.
Mammalian cells have four pathways to repair DSBs:
canonical non-homologous end joining (NHEJ), homologous recombination (HR), alternative NHEJ (altNHEJ), and single strand annealing (SSA). Accelerated heavy-ion particles with high linear energy transfer (LET) induce complex clustered DNA damage including DSBs, single strand breaks, and base damages
within one or two helical turns of DNA. The clustered
DNA damage is considered as an obstacle to eﬃcient
repair and aﬀects the pathway choice for DSB repair.
After exposure to low-LET radiation, NHEJ is thedominant repair pathway throughout the cell cycle,
whereas HR works only in the late S/G2 phase. AltNHEJ and SSA are considered to be functional only
when both the NHEJ and HR are impaired.1) However, the repair mechanism after heavy-ion irradiation
has not been fully understood. Our previous study
using mammalian cells and speciﬁc inhibitors against
NHEJ or HR suggests that NHEJ is the major repair
pathway after 2 Gy of heavy-ion irradiation.2) In addition, we have shown that HR is favored after heavyion irradiation in G2-phase, although HR repairs DSBs
less eﬃciently after heavy-ion irradiation than after Xray irradiation.3) Moreover, recruitment of Rad51 (HRfactor) to DSB is suppressed by high dose (>15 Gy)
heavy-ion irradiation,4) suggesting that the pathway
choice is dependent on the cell cycle, LET, and dose.
In this study, we examined the modiﬁcation of
CTBP-interacting protein (CtIP) after heavy-ion irradiation. CtIP is involved in end-resection of DSBs
for generating 3′ -single strand DNA, which promotes
HR, SSA, and alt-NHEJ.5) CtIP is phosphorylatedby active ATM as well as cyclin-dependent kinase in
S/G2 phase. Phosphorylation of CtIP facilitates its
interaction with BRCA1 and Mre11/Rad50/Nbs1 nuclease complex. Recent studies suggest that the balance between 53BP1-Rif1 and CtIP-BRCA1 controls
the pathway choice. Thus, the choice between NHEJ
and HR/alt-NHEJ/SSA is determined by which among
end-joining or end resection occurs ﬁrst.6)
Exponentially growing HeLa cells were irradiatedwith argon ions (LET = 300 keV/µm) of diﬀerent doses (2–30 Gy), and chromatin fractions wereobtained and subjected to an immunoblot analysis(Fig. 1). In unirradiated cell extracts (at 0 hour), both
phosphorylated and non-phosphorylated forms of CtIP
∗1

RIKEN Nishina Center- 196 -

X
2 Gy

CtIP
DNA-PKRad51
γH2AX
lamin b1

5 Gy

15 Gy

30 Gy

0 1 3 8 1 3 8 1 3 8 1 3 8 (h)phosphorylated
unphosphorylated

Ar
2 Gy

5 Gy

15 Gy

30 Gy

0 1 3 8 1 3 8 1 3 8 1 3 8 (h)CtIPphosphorylated
unphosphorylated

DNA-PKRad51
γH2AX
lamin b1
Fig. 1. Immunoblot analysis of chromatin-bound repair
proteins after irradiation. HeLa cells were irradiatedwith indicated doses of X ray or Ar ions. Tritoninsoluble fractions (chromatin fractions) were preparedat indicated time points following irradiation and subjected to immunoblot. CtIP, phosphorylated DNA-PK,
Rad51, and phosphorylated histone H2AX (γH2AX)
were detected. Arrowheads indicate the retarded modiﬁed forms, which were absent in X-ray irradiated extracts. Lamin B1 was detected as a loading control.

were detected. The level of phosphorylated forms increased after both 15 and 30 Gy of X-ray irradiation.
Argon-ion irradiation induced phosphorylation at thelower dose (2–5 Gy), suggesting that the end-resection
is enhanced after heavy-ion irradiation. In addition,
we found a more retarded form of CtIP after high dose(>15 Gy) of argon-ion irradiation. The retarded form
may be hyperphosphorylated or modiﬁed by small proteins such as ubiquitin or SUMO. Moreover, we observed the same form after the carbon-ion (LET =80 keV/µm) irradiation (data not shown).
We also detected phosphorylated DNA-PK (NHEJ
factor) and Rad51 (Fig. 1). The amount of phosphorylated DNA-PK was dependent on the dose, whereasthat of Rad51 increased up to 5 Gy after argonirradiation and decreased at 15 Gy irradiation as previously reported.4) These results suggest that CtIP
can promote alt-NHEJ and/or SSA at high doses(>15 Gy).

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)

References
1) R. Ceccaldi et al., Trends Cell Biol. 26, 52 (2016).
2) M. Izumi et al., RIKEN Accel. Prog. Rep. 53, 24 (2020).
3) M. Izumi et al., RIKEN Accel. Prog. Rep. 54, 33 (2021).
4) M. Izumi et al., RIKEN Accel. Prog. Rep. 55, 174(2022).
5) P. Cejka et al., Annu. Rev. Genet. 55, 285 (2021).
6) C. Escribano-Diaz et al., Mol. Cell 49, 872 (2013).

2- 197 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Examination of the direct visualization toward adverse events causedby space radiation
A. Sakaue-Sawano,∗1 M. Izumi,∗2 T. Abe,∗2 and A. Miyawaki∗1
The cellular response to DNA damage varies according to the cell types and the cell cycle phases as wellas the extent of DNA damage. In the early 1960s,
Terasima et al.1) employed a method of selectively harvesting cells in M-phase (mitotic shake-oﬀ) to examine
cell cycle-dependent responses to DNA damage causedby X-ray irradiation in HeLa cells. They concluded
that cell survival was minimal when irradiation was
executed during the mitotic (M) and late G1 or early
DNA synthesis (early S) phases whereas it was maximal during the early postmitotic (early G1) and premitotic (S to G2) phases. This view has been widely
accepted to date. However, conventional methods thatuse pharmacological reagents and the above-mentioned
mitotic shake-oﬀ method should have artifactual effects on cells or may be incapable of complete cellcycle synchronization, especially of highly proliferative
tumor cells.
Recently, various cell-cycle visualization methods
using ﬂuorescent proteins (FP) have been developed,
making it possible to directly analyze the cell cycle stages without synchronization and thus withoutaﬀecting normal cell functions. Our original Fucci(ﬂuorescent ubiquitination-based cell cycle indicator)
technique skillfully utilizes the degradation properties of Cdt1 and Geminin (which undergo cell cycledependent proteolysis), two important proteins that
contribute to normal cell cycle progression. When the
degradation domains of Cdt1 and Geminin are conjugated to Red or Green FP, respectively, the cell cycletransition from G1 to S phase is highlighted with highcolor contrast, like a traﬃc light: red to green whichmean “stop” and “go,” respectively (Fig. 1).2) We will
not go into details here, i.e. Fucci (SA) highlights nuclei of cells in G1 phase in red and those of cells in
S-G2-M phases in green. Furthermore, the improved
Fucci (CA) is able to identify clear interphase boundaries between G1, S, and G2 phases (it highlights G1
phase in red, S phase in green, and G2-M phases in yellow). Then we have successfully demonstrated S phasemaximal sensitivity of HeLa cells to UV radiation.3)
In the coming era when humans are once again traveling to the Moon and Mars as represented by “Artemis
mission,” it should be necessary to reevaluate the impact of space risks such as radiation and microgravity.4) Various FP-based approaches have been initiatedto directly study the eﬀects of space radiation on living
cells.5,6) Live imaging technology using FPs is expected
to make signiﬁcant contributions to the direct visual∗1∗2

RIKEN Center for Brain Science
RIKEN Nishina Center- 198 -

Fig. 1. Cell cycle-phasing capabilities of the Fucci technology. Domain structures of each Fucci repertoire (upper)and cell-cycle phasing capabilities (lower) are shown.
For reasons of space, we will not go into details, butplease review the original paper to understand Fucci’s
technology in general. Data were adapted from SakaueSawano et al.3)

Fig. 2. Example of an experiment to evaluate the eﬀects
of heavy-ion irradiation using Fucci Live Imaging. The
human Fibrosarcoma cell line; HT1080/Fucci (CA) 5
cells were irradiated with indicated doses for γ-ray,carbon-ion (LET = 50.9 keV/µm) or argon-ion (LET
= 185 keV/µm), respectively. Live cell imaging wasimmediately performed using an LCV100 computerassisted ﬂuorescence microscope capable of visualizing
eight samples simultaneously.2,3) The data are superimposed snapshots of DIC, Green FP and Red FP 36
hours after irradiation.

ization and detailed understanding of radiation-related
adverse events.
We planned to use Fucci (CA) to visualize responses

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)

to diﬀerent types and doses of heavy-ion irradiation tounderstand the heterogeneity or plasticity of cultured
tumor cells or non-tumor cells. However, the establishment of a seamless experimental system for time-lapse
imaging of living cells before and after a series of irradiations is too challenging due to various physicallimitations. Accordingly, we have compromised to use
the E5 beamline at the RIKEN RRC for visualizing
live cell behavior immediately after heavy-ion irradiation. We proceeded to evaluate the response patternsof cell-cycle populations, their heterogeneity and reproducibility (Fig. 2). Due to the insuﬃcient number ofexperiments to verify biological diﬀerences, we would
like to carry our conclusions to the next report. We willconduct further replicated experiments for a comprehensive understanding based on quantitative analysis.
References
1) T. Terasima et al., Nature 190, 1210 (1961).
2) A. Sakaue-Sawano et al., Cell 132, 487 (2008).
3) A. Sakaue-Sawano et al., Mol. Cell 68, 626 (2017).
4) E. Afshinnekoo et al., Cell 183, 1162 (2020).
5) S. Furukawa et al., Biomed. Res. Int. 2020, 4703286(2020).
6) K. Takahashi et al., NPJ Microgravity 7, 2 (2021).

2- 199 -

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Eﬀects of heavy-ion beam irradiation on non-model fruit ﬂy,
Drosophila miranda
M. Ogawa,∗1 K. Tsuneizumi,∗2 T. Abe,∗2 and M. Nozawa∗1,∗3
Irradiation has been a useful tool for making deletion mutants and establishing strains with balancer
chromosomes in Drosophila melanogaster.1) These ﬂies
have been fundamental resources in the ﬁelds of genetics, development, evolutionary biology, and so on.
However, irradiation has so far been applied primarily only to this model species of Drosophila. If thesame resources become available for other Drosophila
species, researchers working on other ﬂy species canutilize these resources for a variety of studies. For example, D. miranda acquired the so-called neo-sex chromosomes by fusing an autosome with the ordinary Y
chromosome approximately a million years ago, and it
has a high potential for elucidating the early evolutionary phase of sex chromosomes.2,3) The purpose of thisstudy is, therefore, to examine the eﬀects of heavy-ion
beam irradiation on the fertility and the genome of
D. miranda.
We irradiated the iron (Fe)-ion beam (806 keV/µm;
0.5, 1, or 2 Gy) to the ﬂies with 3–4 days after eclosion.
For irradiation, 15-mL tubes were used, in which 3 mLof the medium consisting of 1% agar and 50% grape
juice was poured at an angle of 30◦ . Five males with
the irradiation of the Fe-ion beam were then crossedwith ﬁve virgin females on the same (zeroth) day of theirradiation in a vial containing a normal corn medium(Fig. 1). On the 1st, 4th, and 7th days after irradiation, only the males were transferred to a new vial
and crossed with another ﬁve virgin females. After 3
days of crossing, all the females were discarded fromeach vial. All the males were also discarded with fe-

males on the 10th day. The number of F1 ﬂies eclosed
in each vial was counted. To consider variations, weprepared four vials (that is, 5 males × 4 vials) for each
irradiation condition as replicates. Among the F1 individuals (Fig. 2), we extracted genomic DNA fromeach of the ﬁve males from the 1–3 days vials derived
from the males with irradiation of 2 Gy indicating alower fertility, and resequenced the genomes using Illumina HiSeq X. Following sequencing, the regions withmapping depth of zero in the F1 individual but of atleast 1 in the wildtype individuals were regarded as
the candidate regions of deletions. The same experiments were also conducted for the argon-ion beam(Ar, 189 keV/µm; 1 Gy) and the carbon-ion beam (C,30 keV/µm; 5 Gy) and the genomes of two F1 males
were sequenced for each ion beam.

Fig. 2. Transition of male fertility after Fe-ion irradiation.

Using the strategy described, we successfully detected a number of genes containing the candidate regions of deletions on the Y/neo-Y chromosomes (Table 1). However, deletions were also detected on theX/neo-X chromosomes, which was not expected because the X/neo-X chromosomes were inherited only
Table 1. Number of genes in which deletions were detected.

Fig. 1. Crossing experiments following irradiation.
∗1
∗2
∗3

Department of Biological Sciences, Tokyo Metropolitan University
RIKEN Nishina Center
Research Center for Genomics and Bioinformatics, Tokyo
Metropolitan University- 200 -* The average number of genes with deletions per individual is shown. Only the genes in which deletions weredetected within the exons were counted.

Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 56 (2023)

from the non-irradiated females. We speculate thatsequence polymorphism between each F1 male and reference genomes caused such erroneous identiﬁcations.
We would like to optimize the conditions for making
mutants with large deletions in future studies by repeating the irradiations under various conditions.
This research was supported by the KAKENHI(21H02539), granted to MN.
References
1) R. F. Grell et al., DIS 30, 71 (1956).
2) D. Bachtrog et al., Nature 416, 323 (2002).
3) M. Nozawa et al., Nat. Commun. 7, 13659 (2016).

2- 201 -

IV. OPERATION RECORDS

Ⅳ. OPERATION RECORDS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Program Advisory Committee meetings for nuclear physics and formaterials and life sciences
H. Ueno ∗1
There are two Program Advisory Committees(PACs) that are responsible for reviewing submitted
proposals in the ﬁelds of nuclear physics (NP-PAC)
and materials and life science (ML-PAC). The NPPAC is co-organized by the RIKEN Nishina Center(RNC), the Center for Nuclear Study (CNS), the University of Tokyo, and the Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies(IPNS), KEK. The NP-PAC reviews experimental programs at RI Beam Factory (RIBF), whereas the MLPAC reviews those at the Rutherford Appleton Laboratory (RAL) and RIBF.
NP-PACThe 23rd NP-PAC meeting was held in a hybrid format on December 5–7, 2022 at 9:00–18:30 JST,1) where
40 proposals were submitted and reviewed. One letterof-intent was also submitted. For the ﬁrst time in three
years, the committee members and the experiment representatives participated in a face-to-face meeting, although the audience participated online. Proposals
were evaluated on the basis of ﬁve grades: S, A, B,
C, and D. Those with a grade of B or higher were approved, of which those with a rating of S or A will begiven priority for beamtime allocation. Table 1 summarizes the outcome of the 23rd NP-PAC meeting.
The members of the 23rd NP-PAC meeting were
M. J. G. Borge (Chair, Consejo Superior de Investigaciones Cientíﬁcas), S. Grevy (Centre dÉtudes Nucléaires de Bordeaux Gradignan), M. Dasgupta (The
Australian National Univ.), J. Dilling (Ork Ridge
National Laboratory), M. Gorska (GSI Darmstadt),
T. Kawabata (Osaka Univ.), M. Matsuo (Niigata
Univ.), R. Zegers (Michigan State Univ.), N. Aoi (Osaka Univ.), R. Charity (Washington Univ. in St.
Louis), G. Martínez-Pinedo (Technische Univ. Darmstadt / GSI), I. Moore (Univ. Jyväskylä), T. Saito(RIKEN), P. J. Woods (Univ. Edinburgh), A. Vitturi(Univ. Padova), and X. Zhou (Chinese Academy of
Sciences).
ML-PACThe 23rd ML-PAC meeting was held in January
2023.2) At this meeting, only proposals for the use of
the RIBF were solicited, and not proposals for the useof muon beams at RAL. The one submitted RIBF proposals was reviewed, where the review was conducted
through email, in consideration of the number of applications. For experimental proposals using RIBF, the∗1

Table 1. Summary of the outcome of the 23rd NP-PAC
meeting. The sum of the proposals ranked with S and
A is listed in the “approval” columns.
23rd NP-PAC (December 5–7, 2022)
beam time (days)
proposal number
requestapproval

requestapproval

RILAC (GARIS, ...) 0
AVF (CRIB, ...)
3
RRC (KISS, ...)
4
BigRIPS/ZD
25
SHARAQ/OEDO
1
Rare-RI Ring
1
SAMURAI
6

0
1
3
10
1
1
4

0
32.5
41
151.85
6
17.5
63.5

0
11
18
45
2.5
9
25.5

( BigRIPS-related
Total

16
20

238.85312.35

82
111

33
40

)

same evaluation grade as for NP-PAC was adopted.
The outcome of the meeting is summarized in Table 2.
The members of the 23rd ML-PAC meeting were
A. D. Hillier (Chair, RAL-ISIS), T. Adachi (Sophia
Univ.), J. Kishine (The Open Univ.
Japan),
Y. Kobayashi (The Univ. Electro-Communications),
Y. Miyazawa (Yamagata Univ.), K. Shimomura (KEK),
T. Takayanagi (Saitama Univ.), Z. Qin (CAS-IMP),and I. Yamauchi (Saga Univ.).
Table 2. Summary of the outcome of the 23rd ML-PAC
meeting. For the RIBF proposals, the sum of the proposals ranked with S and A is listed in the “approval”
columns.
23rd ML-PAC (January 2023)
beam time (days)
proposal number
request
RAL
RIBF
AVF
Total

approval

requestapproval—no call for proposals—
1
1

1
1

6
6

4
4

References

1) http://www.nishina.riken.jp/RIBF/NP-PAC/ .
2) http://www.nishina.riken.jp/RIBF/ML-PAC/ .

RIKEN Nishina Center- 203 -1

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Electric power consumption of RIKEN Nishina Center in 2022
M. Kidera,∗1 T. Maie,∗1 S. Watanabe,∗1 E. Ikezawa,∗1 and O. Kamigaito∗1
A comparison of the electricity consumption of
RIKEN Nishina Center (RNC) for each month in 2022with those in 2020 and 2021 is presented in Fig. 1. The
large increase in power consumption in March 2022 ascompared with that in March 2021 may be attributed
to the RI Beam Factory (RIBF) experiment started on
March 18, 2022, whereas, in 2021, it started in April.
The lower power consumption in November 2022 compared to that in November 2021 was caused by a delayin the commencement of the RIBF experiment owing
to the failure of the BigRIPS chiller.

Fig. 1.

∗1

In 2022, the total annual power consumption of the
RNC was 67,338 MWh, an increase of 6% when compared 2021. This increase could be attributed primarily to the RIBF experiment conducted in the previous
period, as mentioned earlier. The total power of the
RNC reached a maximum of 16.6 MW in April 16th
when the uranium (238 U) beam was being tuned for
the RIBF experiment.

Electricity consumption at RNC for each month in 2022 when compared with that in 2020 and 2021.

RIKEN Nishina Center- 204 -

Ⅳ. OPERATION RECORDS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

RILAC operation
H. Yamauchi,∗1 M. Fujimaki,∗2 N. Fukunishi,∗2 H. Hasebe,∗2 Y. Higurashi,∗2 E. Ikezawa,∗2 H. Imao,∗2
O. Kamigaito,∗2 K. Kaneko,∗1 M. Kidera,∗2 M. Komiyama,∗2 R. Koyama,∗1 K. Kumagai,∗2 T. Maie,∗2
T. Nagatomo,∗2 T. Nakagawa,∗2 T. Nishi,∗2 T. Ohki,∗1 J. Ohnishi,∗2 H. Okuno,∗2 K. Oyamada,∗1 K. Ozeki,∗2
N. Sakamoto,∗2 K. Suda,∗2 J. Suzuki,∗1 M. Tamura,∗1 A. Uchiyama,∗2 S. Watanabe,∗2 T. Watanabe,∗2
Y. Watanabe,∗2 K. Yamada,∗2 and A. Yusa∗1
We report on RILAC operations in 2022. Beam
service started in January 2021, and is frequently interrupted due to high X-rays from the ﬁrst and last
cryomodules (CM1, CM3) of SRILAC.1) These X-rays
were caused by ﬁeld emission from the cavities andhave been handled by changing the balance of the acceleration voltage. To improve the condition of cavities, we applied pulsed high-power radio-frequency(RF) processing in November and successfully reduced
the ﬁeld emissions. The beam service was restarted
in December and continued up to the present. Somestatistical data regarding the RILAC operation fromJanuary 1st to December 31st, 2022, are provided inTable 1.
Table 1. Statistical data of RILAC operation from January 1st to December 31st, 2022.

Operation time of RILAC

3856.9 h

Mechanical problems

27.0 hStandalone RILAC

3352.5 h

Injection into RRC

0.0 h

Total beam service time of RILAC

3352.5 hDuring the summer maintenance period, we updated
the RF control panel for the RILAC injector system,
and all the RF systems at RILAC can now be operated
remotely. Other maintenance works performed during
the reporting period are listed below.
(1) Replacement of TMPs for tank #5, coupler of
middle cryomodule of SRILAC (CM2) and RFQ.
(2) Replacement of power supplies for transistor
amp. of tank #1, auto gain controller of A1
and A2, and ﬁlament of tank #5.
(3) Parallelization of cooling water lines for vacuum
pump of tank #5, #6 .
(4) Renewal of chillers for INCAP in tank #1, #2,#5, #6.
(5) Installation of Direct-Current Current Transformer (DCCT) for power supplies of steerer∗1∗2

SHI Accelerator Service Ltd.
RIKEN Nishina Center- 205 -

magnets in High Energy Beam Transport line.
(6) Replacement of valves and joints of cooling system for A1, A2 cavities from brass to stainlesssteel.
(7) Repairment of vacuum leakage in tank #2 andA1 cavity.
We encountered several machine troubles during thereporting beam service period, which are listed as follows.
(1) Repairment of water leakage from the middle
stage amp. of tank #6 and end drift tube of A1
cavity.
(2) Malfunction and repairment of the power supply
for D2 magnet.
(3) Malfunction and replacement of Auto Phase
Control (APC) system of tank #3, power supplies for middle and end stage ﬁlament, PLC
unit of A2 cavity and wide band amp. of tank
#1.
(4) Malfunction and repairment of DC24V control
unit and remote switch for APC of tank #4.
(5) Falling the proﬁle monitor at e12 into beam lineby the trouble of the cylinder.
(6) Thermo-senser trouble of RFQ.
(7) Vacuum deterioration at G3DP by lack of rotary
pump oil.
(8) Trouble and re-calibration of OUTCAP position
monitor of tank #6.
All the problems were successfully ﬁxed, and thebeam service was recovered instantly. The RF system became more stable owing to the temperature
control operation of the second-stage cooling system
introduced last year.2)
References
1) N. Sakamoto et al., Proc. SRF2019, (paper WETEB1,
Dresden, 2019), p. 750.
2) K. Yamada et al., in this report.

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Operation report on the RIKEN AVF cyclotron for 2022
K. Yadomi,∗1 K. Ozeki,∗2 J. Ohnishi,∗2 S. Fukuzawa,∗1 M. Hamanaka,∗1 S. Ishikawa,∗1 K. Kobayashi,∗1
R. Koyama,∗1 R. Moteki,∗1 T. Nakamura,∗1 M. Nishida,∗1 M. Nishimura,∗1 J. Shibata,∗1 N. Tsukiori,∗1
T. Adachi,∗2 M. Fujimaki,∗2 N. Fukunishi,∗2 H. Hasebe,∗2 Y. Higurashi,∗2 H. Imao,∗2 O. Kamigaito,∗2
M. Kidera,∗2 M. Komiyama,∗2 K. Kumagai,∗2 T. Maie,∗2 Y. Miyake,∗2 T. Nagatomo,∗2 T. Nakagawa,∗2
T. Nishi,∗2 H. Okuno,∗2 N. Sakamoto,∗2 K. Suda,∗2 A. Uchiyama,∗2 S. Watanabe,∗2 T. Watanabe,∗2
Y. Watanabe,∗2 K. Yamada,∗2 K. Kamakura,∗3 and Y. Kotaka∗3
Table 2. AVF beam list in 2022.

The annual report on the operation of the RIKEN
AVF cyclotron (hereafter denoted as AVF) for the period January-December 2022 is presented.
AVF delivers beams to the following experimental courses as a stand-alone operation: C01 (machine
study; MS), C03 (RI production), E7V (CNS experiments and RI production), E7A (CRIB experiments),
and E7B (student experiments and RI production). In
addition, AVF is operated as an injector of RIKEN ring
cyclotron (RRC).
The yearly changes in operation statistics since 2019,
and the beams accelerated using AVF in the period aresummarized in Tables 1 and 2. The operation times
for stand-alone operation and injection to RRC in the
period were 2287 hours and 1574 hours, respectively.
The beam service interrupt time caused by trouble of
AVF was 0.7 hours. Because the RIBF experiments
using light-ion beams were not scheduled, AVF-RRCSRC experiments were not performed.
Table 1. Comparison of AVF operation statistics with thatin the previous years.

Development of Xe beam with an energy of approximately 36 MeV/nucleon is now in progress. Although
the Xe beam accelerated using RILAC2-RRC mode sofar (∼10 MeV/nucleon at the exit of RRC) has alreadybeen supplied to the industrial application experiments,
we aim to supply Xe beam with higher energy using
∗1
∗2
∗3

SHI Accelerator Service Ltd.
RIKEN Nishina Center
Center for Nuclear Study, University of Tokyo

AVF-RRC mode, which is frequency-variable. Required
beam current is small, 20 nA or more. As part ofthe beam development, the tests of the acceleration
harmonics H = 3 using 84 Kr14+ at 2 MeV/nucleon
and 84 Kr17+ at 2.4 MeV/nucleon, and the extractionof Xe beams from the 18-GHz ECR ion source were
performed. Furthermore, the change of operation permission for radiation safety was required to accelerate Xe beam. After those preparations, we successfully extracted 900 nA of 136 Xe27+ at 2.4 MeV/nucleon.
However, the beam current of 136 Xe37+ after chargestripping, which is required to accelerate at the RRC,
was too low to extract from the RRC. Therefore, in thenext machine study, we plan to use 129 Xe35+ insteadof 136 Xe37+ with the same energy because an ion yield
after charge-stripping is expected to be nearly an orderof magnitude higher.
To improve equipment, an upgrade of phase probe(AVF-PP) used for isochronous tuning was performed.
A channel switch of the AVF-PP malfunctioned possibly due to age deterioration. The channel switch was
upgraded to a newer model because we have a policy
to replace CIM/DIM system1) to N-DIM2) as an aging
management.
References
1) K. Shimizu, Nucl. Instrum. Methods Phys. Res. A 236,
109 (1985).
2) M. Fujimaki et al., RIKEN Accel. Prog. Rep. 37, 279(2004).

- 206 -

Ⅳ. OPERATION RECORDS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Operation report on ring cyclotrons in the RIBF accelerator complex
K. Kobayashi,∗1 K. Suda,∗2 T. Adachi,∗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. Kidera,∗2 M. Komiyama,∗2 R. Koyama,∗1 K. Kumagai,∗2 T. Maie,∗2
Y. Miyake,∗2 R. Moteki,∗1 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 J. Shibata,∗1 N. Tsukiori,∗1
A. Uchiyama,∗2 S. Watanabe,∗2 T. Watanabe,∗2 Y. Watanabe,∗2 K. Yadomi,∗1 and K. Yamada∗2This paper presents an operation report on ring cyclotrons in the RIBF accelerator complex from January
to December 2022. Table 1 summarizes the beams accelerated by these cyclotrons. Availability can be deﬁned as the ratio of the actual beam service time tothe scheduled beam service time, which is an index
of stable operation of accelerators. When calculatingeach availability for beam service times completed earlier than scheduled, we regarded scheduled times as
actual times. The total actual beam service time was2403.2 hours. The ratio of the beam service time between the experiments conducted in the old (RARF)
and new (RIBF) facilities was 49 : 51. In the RARF,
the actual beam service time was 1178.8 hours with anavailability of 99.1%.
In the RIBF, three beam services were conducted.
The actual beam service time was 1224.4 hours withan availability of 96.3%. The beam services of 238 U
345 MeV/nucleon were conducted primarily to compensate the beam supply suspended owing to the issue
of BigRIPS in December 2021. No major problem occurred during the experiment. The maximum beam
intensity was 82.6 particle nA, and the availability was
97.8%.
Table 1.
Beam
Energyparticle (MeV/nucleon)
12
135
C
14
70
N
20
135
Ne
22
70
Ne
40
95
Ar
56
90
Fe
84

RARF

Kr

136

35.7
7.25
6

136

10.75

Xe

238

U
Ar

10.75
160

Zn
Kr
238
U

345

40

70

RIBF

∗1
∗2

78

AVF-RRC

70

Xe
He
51
V

4

Acceleration mode

RILAC2-RRC

AVF-RRC-IRC

In the 78 Kr beam supply, we recorded the highest
ever beam intensity of 690 particle nA. The power supply of the IRC main coil failed twice because the ﬂow
meter malfunctioned. It took three hours for recovery.
As the beam tuning time was shorter than the expected
time and the beam service for 20 days started earlier
than scheduled, the availability was 103.0%.
In the 70 Zn beam service conducted in December
2022, severe failures occurred. The fRC-W plate power
supply failed to generate 12 kV DC owing to theground fault of the high-voltage transformer. It took
15 hours to replace the transformer. A beam supply was unstable overnight because a ﬂuctuation in
the receiving voltage in the Nishina memorial building aﬀected the RF systems of RRC and fRC. To
protect equipments, the beam intensity was reduced
to 2/3 of the maximum value using a slit placed after the ion source. However, the beam service wassuspended owing to a vacuum leakage in SRC-MDC3
caused by beam loss. The beam service time was only
148.5 hours, and the availability was 77.4%.
The total availability in the RARF and RIBF was
97.6%.

Summary of accelerated beams in 2022.
Beam course
E5B (Biology)
E3B (RI Production)
E5B (Biology)
E6 (RIPS)
E5A (Industry)
E5B (Biology)
E3A (Industry)
E5A (Industry)
E5A (MS)
E3B (RI Production)
E6 (KEK/MRTOF)
E2B (KEK/KISS)
E3A (JAXA)
E5A (Industry)E2B (KEK/KISS)
E5B (Biology)

BigRIPS/ZDS/SHARAQ
RILAC2-RRC-fRC-IRC-SRC BigRIPS/ZDS/SHARAQBigRIPS/ZDS/F12/SLOWRI/SHARAQSHI Accelerator Service Ltd.
RIKEN Nishina Center- 207 -

Beam intensity (particle nA)
Requested
Actual
2
550.0
100
111.0
2
120.0
500
530.0
1
85.3
2
6.3
1
7.4
1
9.8
1
0.1
10000
10000.0
5000
3306.0
200
240.0
100
125.0
1
100.0
2
314.3
2
29.4
Subtotal
1000
700
120

Beam service time (h)Availability(%)
Scheduled
Actual
24.5
12.9
100.0
6.0
5.9
100.0
3.0
1.2
100.0
120.0
119.3
99.4
192.0
143.8
100.0
12.0
3.7
100.0
30.0
30.0
100.0
336.0
269.9
100.0
0.0
0.0
0.0
24.0
19.0
100.0
288.0
284.1
100.0
108.0
107.9
99.9
36.0
35.0
100.0
48.0
46.1
100.0
96.0
89.5
93.2
28.5
10.7
100.0
1352.01178.8
99.1

818.0
690.0
82.6
Subtotal

192.0
384.0
696.0
1272.0

148.5
395.4
680.4
1224.4

77.4
103.0
97.8
96.3

Total

2624.02403.2

97.6

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Present status of liquid-helium supply and recovery system
T. Dantsuka,∗1 H. Okuno,∗1 M. Nakamura,∗1 S. Tsuruma,∗1 M. Takahashi,∗1 M. Ohshima,∗2 H. Shiraki,∗2
H. Hirai,∗2 K. Kimura,∗2 S. Okada,∗2 A. Mikami,∗2 M. Nagano,∗2 H. Shiba,∗2 and H. Hazama∗2
A liquid-helium supply and recovery system,1) which
can produce liquid helium at a liquefaction rate of
200 L/h from pure helium gas, has been under stable operation since the beginning of April 2001. However, due to increased operational failures caused bydeterioration over time, the liqueﬁer was duplicated in2017. The new liqueﬁer can produce liquid helium at aliquefaction rate of 220 L/h from pure helium gas. Although the older helium liqueﬁer has been failing since
the summer of 2018, the new helium liqueﬁer provides
a constant supply of liquid helium. The older heliumliqueﬁer was repaired in February 2020.
The volumes of liquid helium supplied each year
from 2001 to 2021 are illustrated in Fig. 1. From 2001
to 2013, there was a gradual increase in the supplied
volume, with two decrements in 2009 and 2011. In
2014, the supplied volume decreased owing to a system malfunction. However, in 2015, it returned to its
original value. In 2016, the supplied volume decreased,
whereas it increased slightly in 2017 and signiﬁcantly
in 2018. In 2019, approximately 140,000 L of liquid
helium was supplied despite the high price of heliumgas. In 2020, a supply volume decrease of approximately 15,000 L was caused by the inﬂuence of the
new coronavirus.

Fig. 1.
∗1∗2

Moreover, the purity of helium gas recovered fromthe laboratories has gradually deteriorated. Currently,
the impurity concentration in the recovered gas isapproximately 1700 ppm, which aﬀects the liquefaction process and makes continuous operation diﬃcult.
Therefore, improving the purity of the recovered helium gas is necessary. As one of the causes, the purityof the recovered gas from gas holder E was found to be
down to about 95%.
Furthermore, the volume of helium gas recoveredfrom each building in the Wako campus as well as thevolume transported to the liquid-helium supply and recovery system were measured. The recovery eﬃciency
was calculated as the ratio of the amount of recovered
helium gas to the amount of supplied liquid helium.
The recovery eﬃciency for the buildings on the south
side of the Wako campus, i.e., the Cooperation Centerbuilding of the Advanced Device Laboratory, Chemistry and Material Physics building, and Nanoscience
Joint Laboratory building, increased to approximately
98%.
Reference
1) K. Ikegami et al., RIKEN Accel. Prog. Rep. 34, 349(2001).

Volumes of liquid helium supplied to various laboratories for each ﬁscal year from 2001 to 2021.

RIKEN Nishina Center
Nippon Air Conditioning Service K.K.

- 208 -

Ⅳ. OPERATION RECORDS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Operation of BigRIPS cryogenic plant
K. Kusaka,∗1 M. Ohtake,∗1 K. Yoshida,∗1 M. Ohshima,∗2 A. Mikami,∗2 H. Hazama,∗2 H. Shiraki,∗2 H. Hirai,∗2
K. Kimura,∗2 M. Nagano,∗2 H. Shiba,∗2 and S. Okada∗2
Following the accident that occurred on December
3, 2021,1) the main motor of the BigRIPS compressor
unit was shipped to the manufacturer’s factory and disassembled. Damages were found in the bearing units
on both the coupling and anticoupling sides. In particular the bearing unit on the coupling side was heavily
damaged such that the ribbon retainer was destroyed
and the surfaces of the bearing balls and rings were ruined (Fig. 1). We also found that the size of the housing
for the damaged bearing unit was 20 µm larger than its
standard dimension (+0 to 25 µm). After cleaning therotor and stator, the motor unit was reassembled using new bearing units and the re-manufactured bracket
housing. In addition to mechanical maintenance, theinsulation was also examined, and little deteriorationof the stator insulation was noticed. We decided toreplace the motor unit in the summer maintenance period.
Fig. 2. Compressor unit with the new motor.

Fig. 1. Damaged bearing unit, disassembled from the coupling side of the motor unit.

We performed two continuous operations of the BigRIPS cryogenic plant in 2022. The ﬁrst operation
period was from February 22 to June 13 and the second was from November 16 to December 28. Between
these dates, we replaced the motor unit with a new one(Fig. 2). Figure 3 depicts the vibration accelerationsin the vertical and horizontal directions as functions of
the total operation time. Three rapid increases in thevibration acceleration at the operation times of 59,000,
71,000, and 78,541 indicate that the damage in the
bearing unit occurred in December 2016, June 2019,∗1∗2

RIKEN Nishina Center
Nippon Air Conditioning Services Co., Ltd.

- 209 -

Fig. 3. Vibration acceleration of the compressor unit.

and December 2022.1) The red arrow at the operation
time of 81,235 hours indicates the replacement of the
motor unit. Although the vibration acceleration does
not change signiﬁcantly, the typical operation currentof the motor unit decreased from 30.0 to 26.6 A.
In 2022, another incident occurred: the damage of
the ﬁrst expansion turbine T1 in the refrigerator. We
visually inspected T1 and T2 turbines during every
summer maintenance. It was found that the bladesof the expansion wheel of the T1 turbine were broken (Fig. 4). The T1 cartridge was then sent to its
manufacturer, Linde, and disassembled. Linde reportsthat the fractured surface indicates the typical characteristics of a low-cycle fatigue (LCF). The expan-

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 56 (2023)

sion and compressor turbine wheels are replaced withnew ones and re-assembled with new axial bearings.
Before remounting the T1 cartridge on the refrigerator, we investigated the inside of the refrigerator using
a ﬁberscope. No fragments but tiny metal dust was
found in the downstream piping of the T1 expansion
turbine. After the dust was removed using a vacuum
cleaner, the T1 turbine was mounted on the refrigerator. We switched the refrigerator on for pre-coolingon November 16, and the STQ1-5 cryostats were ﬁlledwith liquid helium on December 3. Although the average liquefaction rate of 26 m3 /h is the same as before,
the rotation speed of 4450 rps of the T1 turbine during
the steady-state operation was lower than its design
value of 4600 rps. The origin of the LFC and the lower
rotation speed of the T1 turbine are currently underinvestigation.

Fig. 4. T1 expansion turbine wheel with broken blades.

Reference
1) K. Kusaka et al., RIKEN Accel. Prog. Rep. 55, 182(2022).

2- 210 -

Ⅳ. OPERATION RECORDS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Operation of Pelletron tandem accelerator
T. Ikeda,∗1 K. Inayoshi,∗2,∗1 and H. Sato∗1
The Pelletron tandem accelerator (5SDH-2) provides
ion beams accelerated by up to 1.7 MV for sample irradiation, material analysis, and developments of detectors used in RIBF. This accelerator is registered as a
joint-use equipment (ID: WE0429)1) at the Wako campus and is managed by the Detector Team of RNC.
Fig. 1 shows the conﬁguration of the accelerator, four
beam lines, and two ion sources. One ion source is
the RF charge-exchange type, referred to as Alphatross and is used to generate He− ions. The otheris the Source of Negative Ions by Cesium Sputtering(SNICS), which can generate almost all other negativeions. Till date, ion species of H, He, B, C, O, andAu have been mainly accelerated in the range of 0.5–
1.7 MV. For example, the energies of He2+ and 12 C6+
are 5.1 and 11.9 MeV, respectively, upon the application of 1.7 MV.

glass capillary5) and microbeam irradiation to induce
damage in DNA of mammalian cells.6) The productionof γ rays based on proton-induced resonance reactions
is available for a cross-section measurement in an international summer school, Nishina School, and for calibration of Ge detectors using high energy γ rays up
to 10.8 MeV. Although the 992-keV proton resonancein the reaction of 27 Al(p, γ)28 Si.7) BL-W30 was previously used for detector calibration;8) however, since2020, it has been dedicated to a new cell irradiation
port equipped with a glass capillary microbeam generator9–11) and an Olympus research microscope. Thisline has a unique feature to irradiate living cells in liquid medium with a short ion range (<100 µm) and astopping power (>200 keV/µm), which is suﬃciently
high to induce double strand breaks of DNA in cell
nucleus.
The total machine time (MT) from January 1 to
December 31, 2022, was 27 days as presented in Table 1. The MT included a machine study (MS) on
acceleration, whereas excluded the conditioning of theion sources.
Table 1. Beam conditions.
Ion
1Fig. 1. Pelletron tandem accelerator and beam lines at
Nishina R&D Building.

4

∗1
∗2

RIKEN Nishina Center
Department of Physics, Toho University- 211 -

Beam current[particle nA]

ExperimentOperation time[days]

1.0–3.2

0.05–980

Irradiation

23

2+

2.28

5–58

RBS

3

1,2,3+

1.0–2.0

7

MS

1

He

B

BL-E45 is dedicated to a sub-mm sized beam irradiation for samples in liquid.2) BL-E15 is used byusers in the ﬁeld of material science to perform Rutherford backscattering (RBS) spectrometry analysis3,4)
and elastic recoil detection analysis (ERDA). The
RBS/ERDA apparatus (Charles Evans and Associates
Model RBS-400) comprises a goniometer to rotate asample and particle detectors. Further, the detectors are located at backward and forward positions
to measure the energies of backscattered (He2+ ) ionsand recoiled particles from the sample, respectively.
The samples and the detectors are inside a vacuum
chamber with a vacuum level of the order of 10−4 Pa.
The intensity of the input He2+ beam of 2.28 MeV isgreater than 10 nA according to the collimated beam
size of 5–10 mm in diameter. On the west side, BLW15 is employed as a multipurpose line for various
equipment. Test systems have been constructed for
proﬁle measurements of ion microbeam produced by

H+

Energy[MeV]

The experiments performed in this facility are listed
below, along with the beam lines and number ofdays of MT. The Nishina School in 2022 was postponed.
(1) Microbeam performance study with H ions using
glass capillaries at BL-W15 and -W30 (9 days)(2) RBS/ERDA experiments at BL-E15 (4 days)(3) Educational experiment of proton capture bycarbon/boron-nucleus for the Nishina School (0days)(4) Development of a charged-particle/γ-ray detector to be used for RIBF experiments including
MS (14 days)
The ﬂuctuation of the acceleration voltage of thePelletron improved from 2 to 0.1% following the overhaul from February to March. The achieved stability
was the best in the last decade and realized the beam
position ﬂuctuation of less than 1 mm (beam size is
10–20 mm) at the samples.

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 56 (2023)

References
1) Research support system, R-COMS (RIKEN ID is necessary), https://riken.simprent.jp/
2) T. Kobayashi et al., Surf. Coat. Technol. 331, 206(2017).
3) L. Jianjun et al., Chem. Sci. 12, 10354 (2021).
4) S. R. Lee et al., Phys. Status Solidi A 219, 23, 2200318(2022).
5) T. Ikeda et al., Nucl. Instrum. Methods Phys. Res. B
470, 42 (2020).
6) T. Ikeda et al., RIKEN Accel. Prog. Rep. 53, 215(2020).
7) R. Mizuno et al., RIKEN Accel. Prog. Rep. 55, S20(2022).
8) F. P. Gustafsson et al., RIKEN Accel. Prog. Rep. 50,
209 (2017).
9) T. Ikeda, Jpn. Soc. Appl. Phys. Rev. 2022, 220205(2022).
10) K. Inayoshi et al., RIKEN Accel. Prog. Rep. 55, 107(2022).
11) M. Kurino et al., in this report.

2- 212 -

Ⅳ. OPERATION RECORDS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Radiation safety management at RIBF
K. Tanaka,∗1 H. Sakamoto,∗1 R. Hirunuma-Higurashi,∗1 H. Mukai,∗1 A. Akashio,∗1 T. Okayasu,∗1 R. Suzuki,∗2
M. Takekoshi,∗2 T. Sato,∗2 K. Igarashi,∗1 S. Iizuka,∗1 N. Usudate,∗1 Y. Shioda,∗1 and M. Murata∗1
The results of radiation monitoring at RIBF, conducted at the border of the facility and the radiationcontrolled area are reported. The residual doses along
the accelerator setups are also presented. In 2022, 238 U
beam of approximately 345 MeV/nucleon was provided
at an intensity of 70 particle nA in April. Then 75 Kr
beam of about 345 MeV/nucleon of 600 particle nA
were used in May and June. Further, 70 Zn beam of approximately 345 MeV/nucleon of 400 particle nA wereused in December.
The dose rates at the boundary of the radiationcontrolled area were monitored. Neutron and γ-ray
monitors were used at three locations: roofs of theRRC, IRC, and BigRIPS. Figure 1 shows the annual
neutron dose at these positions. As the thickness of theradiation shield at IRC roof was relatively small, thedose rate was high. In 2017, additional local-concrete
shield of 1 meter thick was set on a beamline in IRC
room. The dose was successfully reduced. In 2022,
even the highest annual dose of 4.1 µSv/y at the IRC
roof was lower than the legal limit of 5.2 mSv/y. The
dose at IRC roof at 2022 is sensitive to IRC and SRC
operation time. In 2022, these were operated for only
four months. Therefore, the annual dose of IRC roof
was small.

level. Therefore, the radiation dose rate was considerably lower than the legal limit.
The residual radioactivity at the deﬂectors of the cyclotrons was measured immediately before the maintenance work. The residual dose is dependent on factors
such as the beam intensity, accelerator operation time,and cooling time. The data have been obtained at
the cyclotrons maintenance works, when the deﬂectors
were able to accessible. Therefore, the cooling times
were not constant. The dose rates from 1986 are shownin Fig. 2. The dose rates for FRC, IRC, and SRC areshown for the years after 2006, when the RIBF operation started. For AVF, the dose rate increased in 2006
because the radioisotope production was started, andthe beam intensity increased.

Fig. 2. Dose rates of residual radioactivity at the deﬂectorsof 5 cyclotrons.

Fig. 1. Radiation dose at the boundary of the radiationcontrolled area.

The dose rates at the site boundary with Wako city,where the legal limit is 1 mSv/y, were monitored byneutron and γ-ray monitors. The annual dose in 2022
was 9.0 µSv neutrons after the background correction.
The annual dose of the γ-ray was under the background∗1∗2

RIKEN Nishina Center
Daiwa Atomic Engineering Corporation- 213 -The residual radioactivity along the beam lines wasmeasured after almost every experiment. Figure 3
shows the locations of the measurement points wherehigh residual-doses rates greater than 100 µSv/h wereobserved. Table 1 lists the dose rates, beam conditions,and cooling time at the measurement points. The maximum dose was 28 mSv/h at point 15, which is near
the 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 in
March 2022. The water in the closed cooling systems
were partly replaced on October 2021. The results
are shown in Table 2. A liquid scintillation counter(LSC-7400, Hitachi Co. Ltd.) was used for the low
energy β ray of 18 keV from H-3 nuclide. A Ge detector (GC2019, Canbbera Co. Ltd.) was used for γ rays
emitted from other radionuclides. The radionuclides,

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 56 (2023)

Table 1. Dose rates measured at beam lines in 2021.
Points 1–17 indicate the locations where measurements
were taken as shown in Fig. 3.

Dose Date Particle Energy Intensity Decay
Poi
rate
(M/
(MeV/ (pnA) periodnt (μSv/h
D)
u)
(h)
α
7.3
2500
362
1 130 7/27
α
7.3
2500
362
2 260 7/27
343
3 300 7/27 U-238 10.8 300
940
269
4 2200 6/14 Kr-78 50
940
269
5 1700 6/14 Kr-78 50
130
6/14
Kr-78
50
940
269
6
631
269
7 4400 6/14 Kr-78 345
631
269
8 6900 6/14 Kr-78 345
631
269
9 140 6/14 Kr-78 345
200
6/14
Kr-78
345
631
269
10
631
269
11 100 6/14 Kr-78 345
631
269
12 730 6/14 Kr-78 345
631
269
13 2380 6/14 Kr-78 345
3650
6/14
Kr-78
345
631
269
14
631
269
15 27500 6/14 Kr-78 345
631
269
16 910 6/14 Kr-78 345
631
269
17 470 6/14 Kr-78 345

Table 2. Concentrations of radionuclide in the cooling water at BigRIPS, allowable legal limits for drain water,and 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.

except for H-3, were already ﬁltered by an ion exchange
resin set in the closed cooling systems. Although theoverall value of contamination was less than the legal
limit for drain water, as shown in Table 2, the waterfrom the closed cooling system will be dumped into
the drain tank prior to the subsequent operation toprevent contamination in the room in case of a waterleakage.
The E-learning module, which can be accessedanytime and from anywhere (even from the outside
RIKEN), has been used for the re-training to the radiation workers at RIBF. Approximately 612 radiation
workers have completed the training in 2022.
As described above, radiation management to comply with lows and to maintain a radiation level as low
as usual has been conducted successfully.

2- 214 -

Cooling Nuclide
water
BigRIPS H-3
F0 target
H-3
Be-7
BigRIPS Mn-54
Co-56
exit
Co-57
beam
Co-58
dump
Co-60
H-3
BigRIPS Be-7
side-wall Co-57
beam
Co-60
dump
1) read as 4.3× 10-3

Concentration[a] Limit[b] Ratio to(Bq/cm3)(Bq/cm3) limit [a/b]2.0
60
3.3e-2summation
3.3e-29.3
60
1.6e-14.3e-31)30
1.4e-45.0e-31
5.0e-38.2e-40.3
2.8e-37.4e-34
1.8e-33.9e-31
3.9e-26.7e-30.2
3.4e-2summation
0.20
15.8
60
4.3e-13.7e-330
1.2e-44.4e-44
1.1e-46.0e-40.2
3.0e-3summation
0.43

Ⅳ. OPERATION RECORDS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Variation of impurity gas in recovered helium gas for liquid-helium
supply and recovery system
M. Nakamura,∗1 T. Dantsuka,∗1 H. Okuno,∗1 S. Turuma,∗1 M. Ohshima,∗2 H. Hirai,∗2 H. Shiraki,∗2 H. Shiba,∗2
K. Kimura,∗2 S. Okada,∗2 A. Mikami,∗2 H. Hazama,∗2 M. Nagano,∗2 and M. Nakayama∗2
We use recovered helium gas for the liquid-helium
supply system. To measure the purity of the recovered
helium gas, we introduce a gas chromatography equipment and monitor the recovered gas. We observed theimpurities concentration and the recovered helium gas
condition for eﬀective operation.1) In this study, we report the changes in the concentration of the impurity
gases observed in 2022.
The recovered helium was analyzed by SHIMADZU
2014, except on Saturdays and holidays. The datafrom January 4 to December 28, 2022, is shown in
Fig. 1. The left-side axis shows the concentration ofN2 and O2 , and the right-side axis shows that of H2 ,CO2 , and CO. The black, gray, red, blue, and green
lines correspond to the N2 , O2 , H2 , CO2 , and CO concentrations, respectively.
The ﬂuctuation N2 concentration was mostly between 1600 to 1800 and O2 concentration was between
1200 to 1400, almost co-varying with each other. The
N2 concentration is at the same level as that of O2 from
October to December in 2021. The O2 concentration
seems to be slightly higher than that of N2 2021. We
hypothesize that the presence of N2 and O2 is due to
air entrainment during the recovery process.1) However, the ratio of N2 and O2 in our analysis is about
0.7 and not the same as 0.25 of the air. The reason forthis discrepancy cannot be explicated.
The ﬂuctuation of H2 concentration was signiﬁcant.
Typically, H2 concentration stabilized at between 0.1
to 0.2 ppm. The H2 concentration suddenly increased
to 0.5–1.5 ppm on several occasions. However, such a

Fig. 1.
∗1∗2

sudden increase in concentration was limited to a single
day, and the liquid-helium supply and recovery system
was not damaged. The correlation of H2 concentration
ﬂuctuation with that of N2 and O2 is unclear. We presume that H2 impurity intermixed into the recovered
helium gas by a diﬀerent mechanism for N2 and O2 .
CO2 was detected almost daily from July to September. CO2 concentration suddenly increased to 1.2–
10 ppm on several occasions. It seems that CO2 wasdetected before and after the sudden increase in H2
concentration. The reason for this phenomenon cannot
be explicated. However, CO2 can be eliminated immediately from the system because the melting point of
CO2 is much higher than that of N2 and O2 . Therefore,
no problem occurred during the operation because of
CO2 .
We cannot estimate the concentration of CO impurity because these gases were observed only a few times
in this year.
In 2022, we had no serious troubles in the liquidhelium supply and recovery system operations. Especially, our system was not damaged by impurity gases.
However, the concentration of impurity gases continued to exhibit chronic elevation. The concentrationsof N2 and O2 annually become slightly higher. Dealing with such issues will be a critical topic in the near
future. Coping with such problems is an important
subject in near future.
Reference
1) M. Nakamura et al., RIKEN Accel. Prog. Rep. 55, 181(2022).

Impurity concentration in recovered helium gas in 2022.

RIKEN Nishina Center
Nippon Air Conditioning Service KK- 215 -

Ⅳ. OPERATION RECORDS

RIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Fee-based activities performed by the RI application research group
A. Nambu,∗1 H. Haba,∗1 A. Yoshida,∗1 K. Watanabe,∗1 and T. Kambara∗1
This article summarizes the fee-based activities performed by the RI Application Research Group in 2022,
which include the distribution of radioisotopes (RIs)
and utilization of heavy-ion beams in the industry.
Since 2007, RIKEN has distributed RIs to users inJapan for a fee in collaboration with the Japan Radioisotope Association1) (JRIA). The nuclides include
65
Zn (T1/2 = 244 d), 109 Cd (T1/2 = 463 d), 88 Y (T1/2= 107 d), 85 Sr (T1/2 = 65 d), and 67 Cu (T1/2 = 61.8 h)
produced in the RIKEN AVF cyclotron by the Nuclear
Chemistry Research Team of the RI Application Research Group.
According to a material transfer agreement (MTA)
drawn between JRIA and RIKEN, JRIA mediates thetransaction of RIs and distributes them to users. 65 Zn
and 109 Cd are delivered approximately two weeks after the acceptance of an order. 85 Sr, 88 Y, and 67 Cu,
which have short half-lives, are not stocked like 65 Zn
and 109 Cd; instead, they are produced in a scheduled
beamtime after an order is accepted. Therefore, they
are delivered after two or more months. Details regarding RIKEN RIs can be found on the online orderingsystem, J-RAM,2) of JRIA. In 2022, we delivered 5, 1,
5, and 1 shipments of 65 Zn, 109 Cd, 85 Sr, and 67 Cu witha total activity of 17.7, 5, 11.7, and 10 MBq, respectively; there was no shipment of 88 Y. The 67 Cu delivery
was the second since the beginning of its distribution in
2018. The ﬁnal recipients of RIs included six universities, one research institute, and two private companies.
Figure 1 shows the yearly trends in the number of orders and amount of distributed RIs. Compared with
2021, the amounts of distributed 109 Cd and 67 Cu increased, and those of 65 Zn, 88 Y, and 85 Sr decreased.
The amount of 85 Sr distributed in 2022 was still thesecond highest since the beginning of its distribution.
The number of orders for 65 Zn in 2022 increased again
and reached its highest in the last eight years.
In addition, we also provide 211 At (T1/2 = 7.2 h)through an MTA drawn between Osaka University and
RIKEN, and among University of Tokyo, Saitama Medical University, and RIKEN. 211 At is delivered to theuniversities directly from RIKEN due to its short halflife. In 2022, we delivered a total of 5.4 GBq of 211 At
to Osaka University in 11 shipments, and 250 MBq to
University of Tokyo in 5 shipments.
The Industrial Application Research Team of the RI
Application Research Group promotes the utilization ofheavy-ion beams in the industry. The RIKEN Nishina
Center allows the use of the AVF cyclotron, RILAC2,
and RIKEN Ring Cyclotron (RRC) by private companies in Japan for a fee.3) Currently, the main users
include semiconductor companies that irradiate space∗1

RIKEN Nishina Center

Fig. 1. Number of orders (upper) and amount (lower) of RIs
distributed annually from 2007 to 2022. The distributionof 88 Y, 85 Sr, and 67 Cu started in 2010, 2015, and 2018,
respectively.

use semiconductor devices with 40 Ar, 84 Kr, or 136 Xeions from the RRC to simulate single-event eﬀects dueto the heavy-ion components of cosmic radiation.
The proposals for beam utilization are reviewed bya program advisory committee dedicated to industrialuse (In-PAC).
In January 2022, In-PAC reviewed and approved two
proposals via e-mail. In July, In-PAC held its 19th
meeting, where it reviewed and approved seven proposals, including four new proposals.
In 2022, seven companies executed 25 fee-based
beamtimes, 14 of which used a 84 Kr beam with a total
beamtime of 234 hours, 9 utilized an 40 Ar beam witha total beamtime of 129 hours, and 2 utilized a 136 Xebeam with a total beam time of 20 hours.
References
1) http://www.jrias.or.jp/ (Japanese),
http://www.jrias.or.jp/e/ (English).
2) https://j-ram.org/ (Japanese).
3) http://ribf.riken.jp/sisetu-kyoyo/HIbeam/ (Japanese).

- 216 -

V. EVENTS

Ⅴ. EVENTS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Research strategy with open-closed data utilization in nuclear
physics experiments
H. Baba∗1
A workshop on Research strategy with open-closed
data utilization in nuclear physics experiments1) was
held on March 7th, 2022 at Integrated Innovation
Building of RIKEN Kobe campus in a hybrid format
with both on-site and remote participation. This workshop was supported by RIKEN’s internal fund dedicated to data utilization promotion support.
Open science and open data schemes are currently
being attempted worldwide. RIKEN has also been promoting open science especially in the ﬁelds of life andmedical science.2) For example, in accelerator based
sciences, some particle physics experimental data areopened at CERN.3) Even in open science approaches, it
is recommended that open-closed data be strategicallyselected, rather than all data being open. For example,
regarding satellite data for astronomy, for which open
access is common, the spokesperson is often given a
period of several years of occupied use. This workshop
was held to discuss “What kind of demands and effects can be expected by open data of nuclear physics
experiments at RIBF?.”
There were 19 participants from RIKEN Nishina
Center, RIKEN Information R&D and Strategy Headquarters, Japan Atomic Energy Agency, Hokkaido University, Konan University, Kyoto University, Kyushu
University, Research Center for Nuclear Physics, Osaka University, University of Miyazaki, University ofTsukuba, Tohoku University, Tokyo City University,
and Yokohama National University. 9 regular talks
and 8 short talks were presented:• Background and purpose of this workshop• RIKEN’s open science initiatives for maximizing
research results• Activities on nuclear data
• Past nuclear data research activities and latest initiatives• Suggestions from the nuclear engineering community regarding RIBF data
• Suggestions from theoretical studies regarding
RIBF data• Research and education at the University ofMiyazaki• Research and education at Tokyo City University• Current status and future of research and education at Konan University• Comments from Nishina Center Promotion Oﬃce(short talk)• Comments from Tohoku University (short talk)• Comments from Kyoto University (short talk)∗1

RIKEN Nishina Center- 217 -• Comments from Research Center for Nuclear
Physics, Osaka University (short talk)• Comments from RIKEN Slow RI Data Team(short talk)• Comments from RIKEN Radioactive Isotope
Physics Laboratory (short talk)• Comments from experimentalist of RIBF User Executive Committee (short talk)• Comments from theorist of RIBF User Executive
Committee (short talk).
As a result of active discussion, several initiatives
were proposed.
1) A detailed database of experiments conducted at
RIBF: make a table of nuclei, energies, targets, measured quantities of approved experiments at RIBF tounderstand what kind of experiments are planned.
2) RIBF experiments assuming data sharing : try toshare not only data but also analysis methods to accumulate knowledge and experience as a software library.
3) Registration to nuclear data: not all RIBF experimental results will be registered, especially those of
master’s thesis. We will continue to discuss methodsof registration.
We are continuing our discussions on how to realize
open-closed data in the nuclear ﬁeld, starting from thisworkshop.
References
1) https://indico2.riken.jp/event/4016/ .
2) https://metadb.riken.jp/osp/ .
3) https://opendata.cern.ch/ .

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN open day 2022
T. Ikeda,∗1 Y. Watanabe,∗1 N. Miyauchi,∗1 Y. Hayashi,∗1 and T. Abe∗1
RIKEN open day, on which its research activities areshowcased to the public, was held in the RIKEN Wako
campus on Saturday, April 23, 2022 in a hybrid style.
Employing an advance reservation system, it was theﬁrst attempt to invite visitors to the campus under the
spread of COVID-19. The number of the visitors waslimited to 300 for each morning and afternoon slot.
The number of applications was 766 and 795, respectively, for the two slots and those of the visitors onsite was 208 and 198, respectively. All visitors were
supposed to spend their time in the Administrative
Headquarters (AH) bldg. in the campus, except when
taking group tours to a few selected research centers.
The contents of the activities from Nishina Center
were (1) group tours for Cyclopedia and RIBF (Fig. 1),(2) exhibition of a large photo panel of the Superconducting Ring Cyclotron (SRC) at the AH bldg. aswell as a poster presentation (Fig. 2), and (3) an online laboratory tour with a navigator to the Nishina
accelerators using RIBF-VR360 (Fig. 3(a)).1) Online
movies made before 2022 were also available. These
contents included collaborations with the Center for
Nuclear Study (CNS) at University of Tokyo and the
Wako Nuclear Science Center (WNSC), IPNS, KEK.
A tin-badge event was held at the AH bldg., in which
visitors could make badges by themselves. The badges
related to the Nishina Center, as shown in Fig. 3(b),were well-received by the participants. The details of
the various activities are in Figs. 1 and 2.

Fig. 2. A large photo panel of SRC displayed as a photogenic place at the Administrative Headquarters bldg.

Fig. 3. (a-1) Online tour using RIBF-VR360 with a navigator for interactive communication. (a-2) the title page(b) three badges marked with yellow circles were designed by Nishina Center. The ﬂowering plant in (i) is
the “Nishina Otome” cherry blossom produced in thiscenter. The symbol “Nh” in (ii) and (iii) stands for theelement Nihonium, that was synthesized in the centerfor the ﬁrst time in the world.

Fig. 1. Group tour to the Nishina Center RIBF bldg., including an explanation session at Cyclopedia followedby visits to SRC and BigRIPS.

For COVID-19 infection control, the group tours to
the Nishina RIBF bldg. were designed carefully. The∗1

RIKEN Nishina Center- 218 -

tours titled “Everything you want to know about stateof-the-art accelerator is right here! ” were held twicein the morning and also twice in the afternoon. The
tour attendance was limited to 12 visitors, who were
escorted by RIKEN staﬀ members between the AH
bldg. and the RIBF bldg., so that each group tour ﬁnished within an hour. The participants were welcomedat Cyclopedia for an explanation by the Nishina staﬀ
instructors, and then enjoyed the views of SRC and BigRIPS from the MB2 ﬂoor with guidance by the other
instructors. At the end of the tour, they got RIBF
souvenirs and left with the RIKEN staﬀ members.
In the AH bldg., a booth with the title “A huge ac-

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 56 (2023)

celerator facility where elements are freely created likemagic” was opened, where a 2.5-m high photo panel of
SRC (Fig. 2), large enough for visitors to take photos
as if they were at the SRC site, was on display. Nearby,
several posters introducing the entire Nishina Center
were displayed, where two Nishina staﬀ members wereassigned to provide explanation.
The online laboratory tour titled “RI Beam Factory: A reclining dragon-like huge underground accelerator complex ” using the RIBF-VR360 was carriedout through a zoom meeting system, where ion sources,
RILAC, RRC, fRC, IRC, and SRC were introduced bya navigator (Fig. 3(a-1)). The virtual tour achieved
111 net views, which was the highest number among
the four virtual tours, including the other centers.
The RIKEN open day 2023 is scheduled on October
14, 2023, which is the ﬁrst trial of the autumn season.
Reference
1) RIBF-VR360 (in Japanese):
ribf/ .

2https://vr.riken.jp/- 219 -

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

Physics of RI: Recent progress and perspectives
M. Kimura∗1 and T. Uesaka∗1 for the Physics of RI Organizing Committee
Introduction: The “Physics of RI: Recent Progress
and Perspectives” conference1) was held from May 30
to June 1, 2022 at RIKEN RIBF, co-organized by
RIKEN Nishina Center and Yukawa Institute for Theoretical Physics (YITP).
The conference adopted a hybrid format, combining in-person and Zoom participation, with approximately 40 in-person attendees, including 3 international participants, and approximately 50 online participants. The conference was held in coordination
with the YITP’s long-term workshop “Mean-ﬁeld andCluster Dynamics in Nuclear Systems (MCD2022),”
which focuses on the theoretical aspects of mean-ﬁeld
and cluster dynamics. The purpose of “Physics of RI”
conference was to complement this with experimental
aspects, presenting the latest experimental results obtained at the experimental facilities regarding unstable
nuclei such as RIBF, along with related theoretical research, and discussing future research directions.
The conference focused on several main topics, including:(1) Comprehensive reports from experimental facilities including RIKEN RIBF
(2) Fundamental properties of unstable nuclei, suchas mass, lifetime, radius, and moment(3) Disappearance of magic numbers, shell evolution, and related gamma-ray spectroscopy experiments(4) Phenomena in the vicinity of drip lines and beyond, such as tetra-neutrons(5) Experimental and theoretical studies on cluster
formation in nuclei(6) Experimental and theoretical studies on nuclear
matter properties and EOS(7) Applications of nuclear technology, such as nuclear conversion(8) Advances in Ab-initio nuclear structure calculations
The conference resulted in several signiﬁcant outcomes:• The conference provided an opportunity for active
in-person discussions, which had been limited dueto the COVID-19 pandemic, fostering exchange
between experimental and theoretical researchers.
• The conference provided a clear outlook on recent progress and future research directions, whichholds great importance for future experimental
and theoretical research at RIKEN.
• Young researchers were given opportunities fororal presentations, promoting their participation∗1

RIKEN Nishina Center- 220 -and contribution to the ﬁeld.
In conclusion, the “Physics of RI: Recent Progress andPerspectives” conference was a successful event thatbrought together researchers in the ﬁeld of nuclear
physics. The conference provided a platform for comprehensive discussions on various topics related to unstable nuclei, including experimental results, theoretical research, and future research directions. The exchange of ideas and discussions among researchers from
diﬀerent backgrounds facilitated the advancements inthe ﬁeld and promoted collaborations between experimental and theoretical researchers.
The organizers express their gratitude to RIKEN
Nishina Center and its staﬀ for their support in hosting
the conference.
Reference1) https://indico2.riken.jp/event/4120/ .

Ⅴ. EVENTS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

Predictions for sPHENIX
M. E. Connors,∗1 Y. M.-Tani,∗2,∗3 G. Nukazuka,∗2 D. V. Perepelitsa,∗4 and A. Sickles∗5
To complete the RHIC mission, sPHENIX was
speciﬁcally designed to measure jet and heavy-ﬂavor
observables with an exceptional level of precision notpreviously achievable at RHIC. This will enhance ourunderstanding of the quark-gluon plasma (QGP) properties and their temperature dependence beyond what
is possible with existing and planned data obtained
from the LHC and other RHIC experiments.
A major goal of the sPHENIX program is to addressquestions regarding the approach to thermalization of
the quark-gluon plasma and its transport properties
using hard probes, such as jets and heavy-ﬂavor particles. The current three-year run plan includes Au +Au, p + Au, and p + p collisions at 200 GeV.1) The Au+ Au dataset provides a large QGP system to study
the QGP properties. The p + Au dataset will allow
for additional studies regarding the intriguing behavior other RHIC experiments observed in ﬂow measurements, as well as transport properties of cold QCD
matter and proton/nuclear structure. The p + p collisions provide a necessary reference for Au + Au andp + Au collisions and allow for additional studies ofproton structure. The upgraded sPHENIX data acquisition system will enable data collection at a high rateto achieve the statistical precision needed for measurements with rare probes. Anticipated measurements include, but are not limited to, jet substructure observables, photon and heavy-ﬂavor tagged jets and comparisons of the production mechanisms of the diﬀerent
upsilon states in all three collision systems.
To maximize the rich physics sPHENIX is capableof accessing, a workshop was hosted July 20–22, 2022
at Brookhaven National Lab (BNL). The goal of theworkshop was to enhance the discussions between theexperimentalists extracting the measurements and thetheorists whose models will be tested and constrainedby the new data. Because sPHENIX will start collecting data in Spring of 2023, this workshop was timely
for theorists wishing to make ﬁnal predictions regarding the anticipated observables before data collectioncommences. In addition, it provided an opportunity
for theorists and experimentalists to propose and discuss new observables.
The workshop was very successful and attracted 106
registered participants. The format of the workshop
was hybrid with slightly less than half of the partici∗1
∗2
∗3
∗4
∗5

Department of Physics and Astronomy, Georgia State University
RIKEN BNL Research Center
Brookhaven National Laboratory
Department of Physics, University of Colorado Boulder
Department of Physics, University of Illinois Urbana Champaign- 221 -

pants attending in person at BNL and the others joining remotely via Zoom. The full agenda is available on
Indico at https://indico.bnl.gov/event/15482/ .
The 30 talks included both experimentalists and theorists, resulting in productive discussions. The experimental talks covered current results obtained from experiments at RHIC and LHC, as well as the capabilities
and planned measurements for sPHENIX. The theory
talks represented various theoretical approaches andtopics. An important outcome of this workshop was
the decision to write a paper collecting the latest theoretical predictions from the presenters. The goal isto submit the paper for publication before sPHENIX
starts collecting its ﬁrst physics data. This collectionof theoretical predictions for sPHENIX will be an extremely useful resource and particularly helpful for citing the theories in future sPHENIX publications.
Reference
1) sPHENIX Beam Use Proposal 2022, sPH-TRG-2022001, https://indico.bnl.gov/event/15148/attachments/
40846/68568/sPHENIX_Beam_Use_Proposal_2022.pdf .

Ⅴ. EVENTSRIKEN Accel. Prog. Rep. 56 (2023)
RIKEN
Accel. Prog. Rep. 56 (2023)

International workshop on “Hadron physics with Kaon beam andrelated topics”
F. Sakuma∗1 for the Workshop Organizer
The international workshop on “Hadron Physics
with Kaon Beam and Related Topics” was held online on October 3–4, 2022. It was organized by
RIKEN Nishina Center and Grant-In-Aid for Specially Promoted Research “Toward revolutionary Nuclear Study via revealing Internal Structure of Kaonic
Nuclei” (MEXT Kakenhi 22H04917), and supported
by Hadron Hall User Association (HUA), KEK Theory Center, RCNP, ELPH, and JAEA ASRC.
The workshop focused on the recent experimental
and theoretical developments in kaon interactions with
nucleons and nuclei, particularly those activities using the unique kaon beams available at J-PARC andDAΦNE. The topics covered by the workshop were:• kaonic nuclei• Γ(1405)• kaonic atoms• kaon-nucleon scattering
The workshop was held fully online using Zoom,
which included 82 participants from 10 countries, with
27 participants from abroad. The scientiﬁc program
comprises plenary sessions held by invited speakers.
The structure of the sessions was set to be accessible to Asian and European participants. Sessions on
both days ran from 16:00 to approximately 23:00 Japan
time, with lunch (dinner) breaks as reported in Table 1.
A screenshot of participants is shown in Fig. 1.

Table 1. Timetable of the workshop.

Fig. 1. Screenshot of online participants.

There were 24 talks, including opening and closing remarks. The session began with the theoretical overviews of low-energy kaon physics, which is an
important probe to understand low-energy QCD. Following that, the latest results and future experimental
prospects at J-PARC, DAΦNE, SPring-8, and LHC, aswell as the latest theoretical developments, were presented. There, discussions were given on the recent
major topics of kaonic nuclei and atoms, Γ(1405), andKbar N scattering, including the latest topics on lattice
QCD calculations. The full program and presentationﬁles are available online at the workshop website.1)
Following the success of the workshops, we are planning to conduct a second workshop around FY2024-25
to continuously discuss physics at the J-PARC and related facilities.
Reference1) https://kds.kek.jp/event/43204/ (Access key required) .

∗1

RIKEN Nishina Center- 222 -

Ⅴ. EVENTS
RIKEN
Accel. Prog. Rep. 56 (2023)

RIKEN Accel. Prog. Rep. 56 (2023)

The 10th users’ meeting on mutation breeding in RIBF “Sustainable
society and creation of specialty products realized byion-beam breeding”
T. Abe,∗1 Y. Hayashi,∗1 Y. Watanabe,∗1 N. Fukunishi,∗1 K. Ishii,∗1,∗2 K. Tsuneizumi,∗1 Y. Shirakawa,∗1
S. Ohbu,∗1 and N. Asakawa∗1
The users’ meeting on mutation breeding in RIBF has
been held the RIKEN Symposium every two years since2003. Moreover, we have published the RIKEN Symposium abstracts and user reports. The 10th symposium was initially scheduled to be held in January 2022;
however due to the Covid-19 pandemic, it was postponed until January 19–20, 2023. The RIKEN Symposium was held in a hybrid manner with 32 on-site and50 online participants. Online participation from remote locations was eﬀective. The participants’ researchﬁelds were categorized by biology (development of fundamental technologies and gene isolation) and breeding as targets (microorganisms, trees, food crops andﬂowering plants). In the 10th meeting, there were notree-breeding researchers, and the number of microalgae
researchers increased. The proportion of other specialities remained relatively the same from recent trends(Fig. 1).1)

FlowerFood crop

Biology

MicrobeFig. 1. The specializations of symposium participants in
2022.

The meeting featured ten presentations and two invited lectures on three research topics: developing
breeding techniques, identiﬁcation of novel genes using
mutants and analysis of gene function, and breedingnew varieties. The invited talks were on bioreﬁnery
using microalgae and upgrade concept of the RIBF accelerators. In addition, a tour of the accelerator facility
was conducted before the meeting.
(1) Development of breeding technology
It is clear that mutations at 30 keV/µm, which havea high mutation rate in Arabidopsis thaliana, are often base substitutions or small deletions of a few bp.
Whereas those at 290 keV/µm, which have a high lethal
eﬀect, are often large deletions of 100 bp or more andchromosome rearrange- ments. Similar results wereobserved with rice.2) Furthermore,we investigated ge∗1
∗2

RIKEN Nishina Center
National Institute of Radiological Sciences, National Institutes for Quantum Science and Technology

Fig. 2. Photograph of on-site participants.

nomic mutations of carbon and argon ions at 100–
300 keV/µm to identify the LETs that increase the rateof large deletions and chromosomal rearrangements in
Arabidopsis.
(2) Identiﬁcation of novel genes using mutants andanalysis of gene function
A sex-determining gene located on the Y chromosome
in a dioecious plant, Silene latifolia, was determined.3)
Other discovered genes can be used for seed size increase in Arabidopsis,4) heat-stress marker in rice5) andbreeding in wheat.
(3) Breeding new varieties
New varieties applied for variety registration in 2018–2022 were three cherry blossoms and one hibiscus by thefarmers, two Chrysanthemum that blooms in all threecolors during the Bon Festival by the Nagasaki Prefecture, and a Satsuma mandarin that can be harvested
one month late and suitable for long-term storage by
the Shizuoka Prefecture.
Users could deepen their understanding of accelerator facilities and accelerator science through invitedlectures and a tour of the accelerator. In the other special lecture, useful mutants, such as those yielding highoil production, have been obtained even in microalgae.
It was conﬁrmed that to realize a sustainable world, we
will continuously contribute to solving problems of energy, environment and food, and create local speciality
products by ion-beam breeding. The next meeting isscheduled to be held in January 2025.
References
1) T. Abe et al., RIEKN Accel. Prog. Rep. 53, 231 (2020).
2) R. Morita et al., Cytologia 86, 303 (2021).
3) Y. Kazama et al., Mol. Biol. Evol. 39, msac195 (2022).
4) V. Q. Nhat et al., Plants 10, 1252 (2021).
5) R. Tabassum et al., Plant Prod. Sci. 24, 230 (2021).

- 223 -

VI. ORGANIZATION AND ACTIVITIESOF RIKEN NISHINA CENTER(Activities, Members, Publications & Presentations)Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

1. Organization
1.1 Organization Chart as of March 31, 2023 (End of FY2022)- 225 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

1.2 Topics in FY2022
Year

Date

2022

Apr. 12022

Oct. 1

Topics in Management
Newly appointed:
Director of RHIC Physics Research Group: Yasuyuki AKIBA
Newly appointed:
Team Leader of RILAC Team: Yoshihide HIGURASHI
Newly appointed:

2022

Oct. 1

Director of Instrumentation Development Group, Team Leader of Rare RI-Ring Teamand SCRIT Team: Tetsuya OHNISHI

2. Finances
A transition of the RNC budget for the past four years is shown in following graph.
Million Yen- 226 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

3. Staffing
At the start of FY2022, there were 127 personnel affiliated with RNC and 386 researchers visiting RNC for research purpose. The following
graphs show a breakdown of personnel into six categories as of April 1, 2022, and a transition of the number of each category.

Permanent Researcher
Contract Researcher
Technical staff
Special Postdoctoral Researcher
Junior Research Associate
External researcher- 227 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

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.

Citation analysis for the past four years
As of April 2023
Year
Indicators

2019

2020

2021

2022

Total number of papers

301

300

298

251

Percentage of papers in top 1%

1.00

1.33

3.4

0.8

Percentage of papers in top 10%

9.63

12.67

14.1

9.6

- 228 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

5. Management
Headed by the RNC Director Hiroyoshi SAKURAI, the RIKEN Nishina Center for Accelerator-Based Science (RNC) consists of:

7 Laboratories
12 Groups with 27 Teams
2 overseas research centers with 3 Groups

as of the end of FY2022. 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:






Coordination Committee
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, 2023)
Hiroyoshi SAKURAI
Director
Osamu KAMIGAITO
Deputy Director (Research Facility Development Division)
Tomoko ABE
Deputy Director (Accelerator Applications Research Division)
Masahiro IWASAKI
Deputy Director (Subnuclear System Research Division)
Kosue MORITA
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, 2023)
Hiroyoshi SAKURAI
Osamu KAMIGAITO
Tomoko ABE
Masahiko IWASAKI
Tomohiro UESAKA
Hideki UENO
Toru TAMAGAWA
Emiko HIYAMA
Masaaki KIMURA
Yuko MOTIZUKI
Kosuke MORITA
Hiroki OKUNO
Nobuhisa FUKUNISHI
Tetsuya ONISHI
Hiromitsu HABA

Director, RNC; Director, Radioactive Isotope Physics Laboratory and Nuclear Transmutation Data Research Group;
Team Leader, Muon Date Team
Deputy Director, RNC; Director, Accelerator Group
Deputy Director, RNC; Director, Beam Mutagenesis Group; Team Leader, Ion Beam Breeding Team
Deputy Director, RNC; Director, Meson Science Laboratory
Director, Spin Isospin Laboratory
Director, Nuclear Spectroscopy Laboratory and User Liaison Group; Team Leader, Outreach Team
Director, High Energy Astrophysics Laboratory
Director, Strangeness Nuclear Physics Laboratory
Director, Nuclear Many-body Theory Laboratory
Director, Astro-Glaciology Research Group
Senior Advisor, RNC
Deputy Group Director, Accelerator Group; Director, High-Intensity Accelerator R&D Group; Team Leader,
Accelerator R&D Team, Cryogenic Technology Team, and High-Power Target R&D Team
Deputy Group Director, Accelerator Group; Director, Research Instruments Group; Team Leader, Beam Dynamics &Diagnostics Team
Director, Instrumentation Development Group; Team Leader, Rare RI-Ring Team and SCRIT Team
Director, Superheavy Element Research Group, RI Application Research Group; Team Leader, Nuclear Chemistry
Research Team and Superheavy Element Production Team- 229 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)
Kanenobu TANAKA
Hideaki OTSU
Naruhiko SAKAMOTO
Hiromi SATO
Toshiyuki SUMIKAMA
Takahide NAKAGAWA
Koji MORIMOTO
Atsushi YOSHIDA
Koichi YOSHIDA
Ken-ichiro YONEDA
Hironobu ISHIYAMA
Hidetada BABA
Hiroyuki Ichida
Masanori Kidera
Yoshihide HIGURASHI
Hideto EN'YO
Yoshitaka HATTA
Yasuyuki AKIBA
Taku IZUBUCHI
Motohide YOKOTA
Toshinari ANZO

Director, Safety Management GroupTeam Leader, SAMURAI Team and Fast RI Data Team
Team Leader, Cyclotron Team and High-Gradient Cavity R&D Team
Team Leader, Detector Team
Team Leader, Slow RI Data Team
Team Leader, Ion Source Team
Team Leader, Superheavy Element Device Development Team
Team Leader, Industrial Application Research Team
Team Leader, BigRIPS Team
Team Leader, RIBF User Liaison Team
Team Leader, SLOWRI Team
Team Leader, Computing and Network Team
Team Leader, Plant Genome Evolution Research Team
Team Leader, Infrastructure Management Team
Team Leader, RILAC Team
Director, RIKEN BNL Research Center
Group Leader, Theory Group, RIKEN BNL Research Center
Director, RHIC Physics Research Group; Group Leader, Experimental Group, RIKEN BNL Research Center
Group Leader, Computing Group, RIKEN BNL Research Center
Office of the Center Director
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 23rd NP-PAC was held on December 5−7, 2022 at RIBF
Members (as of March 31, 2023)
Maria J.G. BORGE (Chair)
Stéphane Grevy
Mahananda Dasgupta
Jens Dilling
Magdalena Gorska
Takahiro Kawabata
Masayuki Matsuo
Remco Zegers
Nori AOI
Robert CHARITY
Gabriel MARTINEZ-PINEDO
Iain MOORE
Takehiko SAITOPhilip J. WOODS
Andrea VITTURI
Xiaohong ZHOU

Consejo Superior de Investigaciones Científicas
Centre d'Etudes Nucléaires de Bordeaux Gradignan
The Australian National University
Ork Ridge National Laboratory
GSI Darmstadt
Osaka University
Niigata University
Michigan State University
RCNP, Osaka University
Washington University in St. Louis
Technische Universität Darmstadt, GSI Helmholtzzentrum für Schwerionenforschung
University of Jyväskylä
RIKEN
University of Edinburgh
Universita' di Padova
Chinese Academy of Sciences

Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)
The 22nd ML-PAC was held on August 22−25, 2022 via e-mail and Web meeting.
The 23rd ML-PAC was held between December 23, 2022 and January 10, 2023 via e-mail.
Members (as of March 31, 2023)
Adrian HILLIER (Chair)
Zhi QIN
Toshiyuki TAKAYANAGI
Yoshio KOBAYASHI
Yutaka MIYAZAWA
Tadashi ADACHI
Ichihiro YAMAUCHI
Koichiro SHIMOMURA
Jun-ichiro KISHINE

ISIS, RAL (UK)
Chinese Academy of Sciences
Saitama University
The University of Electro-Communications
Yamagata University
Sophia University
Saga University
KEK
The Open University of Japan- 230 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Industrial Program Advisory Committee (In-PAC)
The 19th In-PAC was held on July 22, 2022 via Web meeting.
The 20th In-PAC was held between December 12, 2022 and January 6, 2023 via e-mail.

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, 2023)
Hiromi SATO (Chair)
Kouji MORIMOTO
Takashi NAGATOMO
Hiromitsu HABA
Atsushi YOSHIDA
Koichi YOSHIDA
Naoki FUKUDA
Naruhiko SAKAMOTO
Daisuke SUZUKI
Masaki SASANO
Shunji NISHIMURATeam Leader, Detector Team
Team Leader, Superheavy Element Device Development Team
Senior Technical Scientist, Ion Source Team
Team Leader, Nuclear Chemistry Research Team
Team Leader, Industrial Application Research Team
Team Leader, BigRIPS TeamTechnical Scientist, BigRIPS Team
Team Leader, Cyclotron Team
Research Scientist, Radioactive Isotope Physics Laboratory
Senior Research Scientist, Spin Isospin Laboratory
Senior Research Scientist, Radioactive Isotope Physics Laboratory

External members
Shinichiro MICHIMASA
Hidetoshi YAMAGUCHI
Yutaka WATANABE

Assistant Professor, Center for Nuclear Study, University of Tokyo
Lecturer, Center for Nuclear Study, University of Tokyo
Associate Professor, High Energy Accelerator Research Organization, KEK

Ex officio members
Kanenobu TANAKA
Hisao SAKAMOTO

Director, Safety Management Group
Technical Scientist, Safety Management Group

Hot-Lab Safety Review Committee
Members (as of March 31, 2023)
Tetsuya OHNISHI (Chair)
Kanenobu TANAKA
Hisao SAKAMOTO
Hiroki MUKAI
Rieko HIGURASHI
Hiromitsu HABA

Director, Instrumentation Development Group
Director, Safety Management Group
Technical Scientist, Safety Management Group
Technical Staff I, Safety Management Group
Technical Scientist, Safety Management GroupTeam Leader, Nuclear Chemistry Research 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, 2023)
Hideki UENO (Chair)
Osamu KAMIGAITO
Tetsuya ONISHI
Tomohiro UESAKA
Nobuhisa FUKUNISHI
Hiroki OKUNO
Shunji NISHIMURA
Tomoko ABE
Hiromitsu HABA
Kanenobu TANAKA
Ken-ichiro YONEDA
Kouji MORIMOTO
Koichi YOSHIDA

Director, User Liaison Group and Nuclear Spectroscopy Laboratory
Director, Accelerator Group
Director, Instrumentation Development Group
Director, Spin Isospin Laboratory
Director, Research Instruments Group and Deputy Group Director, Accelerator Group
Deputy Group Director, Accelerator Group
Senior Research Scientist, Radioactive Isotope Physics Laboratory
Director, Beam Mutagenesis Group
Director, RI Application Research Group
Director, Safety Management GroupTeam Leader, RIBF User Liaison Team
Team Leader, Superheavy Element Device Development Team
Team Leader, BigRIPS Team- 231 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

External members
Kentaro YAKO
Hidetoshi YAMAGUCHI
Yutaka WATANABE
Observers
Hiroyoshi SAKURAI
Yasuhiro SAKEMIMichiharu WADA
Hiroari MIYATAKE
Daisuke SUZUKI
Tohru MOTOBAYASHI
Hideyuki SAKAI
Hideaki OTSU
Atsushi YOSHIDA
Hironobu ISHIYAMA
Toshinari ANZOSoh OSUKA

Associate Professor, Center for Nuclear Study, University of Tokyo
Lecturer, Center for Nuclear Study, University of Tokyo
Associate Professor, High Energy Accelerator Research Organization, KEK
Director, RNC; Director, Radioactive Isotope Physics Laboratory and Nuclear Transmutation Data Research Group;
Team Leader, Muon Date Team
Director, Center for Nuclear Study, University of Tokyo
Director, KEK Wako Nuclear Science Center
Professor, High Energy Accelerator Research Organization, KEK
Chair, The RIBF Users Executive Committee (RIBF-UEC); Research Scientist, Radioactive Isotope Physics
Laboratory
Senior Advisor, RNC
Senior Advisor, RNC
Team Leader, Fast RI Date Team and SAMURAI Team
Team Leader, Industrial Application Research Team
Team Leader, SLOWRI Team
Director, Nishina Center and iTHEMS Promotion Office
Manager, Nishina Center and iTHEMS Promotion OfficePublic Relations Committee
Upon request of the RNC Director, the Public Relations Committee deliberates and coordinates the following matters:Creating public relations system for RNC
Prioritization of the public relations activities for RNC
Other general and important matters concerning the public relations of RNC

Members (as of March 31, 2023)
Toshinari ANZO (Chair)
Osamu KAMIGAITO
Tomoko ABE
Masahiko IWASAKI
Tomohiro UESAKA
Hideki UENO
Yuko MOTIZUKI
Narumasa MIYAUCHI
Yasushi WATANABE
Motohide YOKOTA

Director, Nishina Center and iTHEMS Promotion Office
Deputy Director, RNC; Director, Accelerator Group
Deputy Director, RNC; Director, Beam Mutagenesis Group
Deputy Director, RNC; Director, Meson Science Laboratory
Director, Spin Isospin Laboratory
Director, Nuclear Spectroscopy Laboratory and User Liaison Group
Director, Astro-Glaciology Research Group
Technical Staff I, Outreach TeamSpecial Temporary Research Scientist, Outreach Team
Director, Office of the Center Director

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 28th MSC was held on May 26, 2021.
Members (as of March 31, 2023)
Shigeo KOYASU
Hiroyoshi SAKURAI
Shoji NAGAMIYA
Robert TRIBBLE
Dmitori DENISOVHaiyan GAO

Executive Director, RIKEN
Director, RNC
Senior Visiting Scientist, RNC
Deputy Director for Science and Technology, BNL
Deputy Associate Laboratory Director for High Energy Physics, BNL
Associate Laboratory Director for Nuclear and Particle Physics, BNL- 232 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

6. International Collaboration (as of March 31, 2023)

Country

China

FinlandFranceGermany

Hungary

Indonesia

Italy

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

Institute of Modern Physics,
Chinese Academy of Science

Physics of heavy ions

Hiroyoshi SAKURAI, Director, Radioactive Isotope
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

School of Physical Sciences,
USTC

Framework

Masahiko IWASAKI, Director, Meson Science
Laboratory

University of Jyvaskyla

Basic nuclear physics and related
instrumentation

Hironobu ISHIYAMA, Team Leader, SLOWRITeam

National Institute of Nuclear
Physics and Particle Physics(IN2P3)

Physics of heavy ions

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Normandy University

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Commissariat à l'énergie
atomique et aux énergies
alternatives (CEA, French
Alternative Energies and Atomic
Energy Commission)・Direction
des Sciences de la Matière”(DSM)

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

The Institut National de Physique
Nucléaire et de Physique desParticules CNRS (CNRS/IN2P3)

Experiments with NEBULA-Plus array

Tomohiro UESAKA, Director, Spin Isospin
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

The Institute of Nuclear Researchof the Hungarian Academy of
Sciences (ATOMKI)

Nuclear physics, Atomic Physics

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

ITB, UNPAD, ITS, UGM, UI

Material science using muons at the RIKENRAL muon facility

Masahiko IWASAKI, Director, Meson Science
Laboratory

Hasanuddin University

Agricultural science and related fields
involving heavy-ion beam mutagenesis using
Indonesian crops

Tomoko ABE, Director, Beam Mutagenesis Group

Institut Teknologi Bandung

Framework

Hideki UENO, Director, Nuclear Spectroscopy
Laboratory

Universitas Padjadjaran

Framework

Hideki UENO, Director, Nuclear Spectroscopy
Laboratory

National Agency for New
Technologies, Energy and theEnvironment (ENEA)

Framework

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

European Center for Theoretical
Studies in Nuclear Physics andRelated Areas (ECT*)

Theoretical physics- 233 -

Masaaki KIMURA Director, Nuclear Many-body
Theory Laboratory

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)
Country

Partner InstituteObjects

RNC contact person

Italy

Istituto Nazionale
Nucleare (INFN)

Physics of heavy ions

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

College of Natural Science, 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

Joint Institute for Nuclear
Research (JINR)

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Russian Research Center“Kurchatov Institute”

Framework

Hiroyoshi SAKURAI, Director, Radioactive Isotope
Physics Laboratory

Paul Scherrer InstituteImprove the performance and reliability ofaccelerator systems

Osamu KAMIGAITO, Director, Accelerator Group

Taiwan Instrumentation Detector
Consortium（TIDC)

Framework

Itaru Nakagawa, Senior Research Scientist, RHIC
Physics Research Group

Center for High Energy and High
Field Physics, Taiwan（CHiP)High energy and nuclear physics

Yasuyuki AKIBA, Director, RHIC Physics Research
Group

Brookhaven National Laboratory

Framework

Yasuyuki AKIBA, Director, RHIC Physics Research
Group

Columbia University

The development of QCDCQ

Yasuyuki AKIBA, Director, RHIC Physics ResearchGroup

Michigan State University

Comprehensive
The use of TPC (Time Projection Chamber)

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

UK

The ISIS Neutron and Muon
Source at the Science andTechnology Facilities Council,
part of United Kingdom ResearchandInnovation,
Rutherford
Appleton Laboratory

Framework

VietnamVietnam Atomic Energy
Commission

Framework

The European Organization for
Nuclear Research (CERN)

R&D and application of micro-pattern gas
detectors (MPGD) technology (RD51
Collaboration)

Yasuyuki AKIBA, Director, RHIC Physics ResearchGroup

The European Organization for
Nuclear Research (CERN)

Collaboration in the ALICE Experiment

Yasuyuki AKIBA, Director, RHIC Physics Research
Group

EURO-LABS

Framework

Tomohiro UESAKA, Director, Spin Isospin
Laboratory

Korea

RussiaSwitzerland

TaiwanUSA

EuropediFisica- 234 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

7. Awards
Awardee, Laboratory / TeamAward

Organization

Date

Tomoko ABE, Director of the Beam Mutagenesis GroupThe 10th Wada Memorial Award

The Japan Mendel Society

Apr. 17

Pieter Christiaan DOORNENBAL, Senior Research
Scientist at the Radioactive Isotope Physics Laboratory

Friedrich Wilhelm Bessel Research
Award

Alexander von Humboldt Foundation

Apr. 25

Kimiko SEKIGUCHI, Visiting Scientist at the Spin
Isospin Laboratory

The 42nd Saruhashi Prize

一般財団法人 女性科学者に明るい
未来をの会

May 29Kai KIKUCHI, Student Trainee at the Nuclear
Spectroscopy Laboratory

29th International Conference on Low
Temperature Physics (LT29)
Poster Award

29th International Conference on Low
Temperature Physics (LT29)
organizing committeeAug. 24

Kenta SUGIHARA, Visiting Scientist at the Safety
Management GroupThe Atomic Energy Society of Japan(AESJ) Data Division Encouragement
Award

Atomic Energy Society of Japan

Sep. 9Rurie Mizuno, Student Trainee at the Radioactive Isotope
Laboratory

The Outstanding Presentation Award

Japanese Society of Radiation
Chemistry

Sep. 12

Tomoko ABE, Director of the Beam Mutagenesis Group

Japanese Society of Breeding Award

Japanese Society of Breeding

Sep. 20

Yusuke KAZAMA, Visiting Scientist of the Ion Beam
Breeding TeamJapanese Society of Breeding Award

Japanese Society of Breeding

Sep. 20

Tomoya HIRANO, Visiting Scientist of the Ion Beam
Breeding TeamJapanese Society of Breeding Award

Japanese Society of Breeding

Sep. 20

Tomoko ABE, Director of the Beam Mutagenesis Group

Japanese Society of Crop Science(CSSJ) Best Paper Award.

Crop Science Society of Japan

Oct. 18

Hiroyuki ICHIDA, Team Leader of the Plant Genome
Evolution Research TeamJapanese Society of Crop Science(CSSJ) Best Paper Award.

Crop Science Society of Japan

Oct. 18

Ryohei MORITA, Technical Scientist at the Ion Beam
Breeding TeamJapanese Society of Crop Science(CSSJ) Best Paper Award.

Crop Science Society of Japan

Oct. 18

Yasuyuki MORITA, Special Post Doctoral Researcher at
the Ion Source TeamThe Young Presentation Award by theBeam Physics Study Group

The Beam Physics Study Group

Mar. 10

8. RIKEN Awards
AwardeeAward

Laboratory

Date

Shigekawa YUDAI

Ohbu Award (桜舞賞)
The 14th RIKEN Research Incentive
Awards (研究奨励賞)

Nuclear Chemistry Research Team

Mar. 23

Yasushi ABE

Ohbu Award (桜舞賞)
The 14th RIKEN Technology Incentive
Awards (技術奨励賞)

SCRIT Team

Mar. 23

Hiromitsu HABA

Eiho Award (栄峰賞)

Nuclear Chemistry Research Team

Mar. 23- 235 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Takashi ABE, Takaharu OTSUKA

Baiho Award (梅峰賞)

Nuclear Spectroscopy Laboratory

Mar. 23

Yoshitaka YAMAGUCHI

Baiho Award (梅峰賞)

Rare RI-Ring Team

Mar. 23- 236 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

The Center Director
Meeting Attendance as Ex Oﬃcio

International Meetings[NuPECC associate member]∗ May 6–7, 2022, hybrid.
∗ December 1–2, 2022, hybrid.
[IUPAP WG9]
∗ June 14–15, 2022, hybrid.
Domestic Meetings[核物理委員会]
仁科センター報告, オンライン, 2022 年 7 月 18 日.
仁科センター報告, オンライン, 2022 年 9 月 7 日.
仁科センター報告, オンライン, 2022 年 10 月 13 日.
仁科センター報告, オンライン, 2022 年 12 月 11 日.
仁科センター報告, オンライン, 2022 年 12 月 12 日.
仁科センター報告, オンライン, 2022 年 12 月 22 日.
仁科センター報告, オンライン, 2023 年 3 月 23 日.

List of Presentations
Presentations[Domestic Conferences/Workshops]
H. Sakurai (invited), “A brief overview of RIBF,” RIBF User Meeting, Online, September 20, 2022.
H. Sakurai (invited), “A brief overview of RIBF,” SAMURAI Workshop, Online, September 2, 2022.
櫻井博儀（招待講演）, 「安心安全な新たな核エネルギー創出のための元素変換研究の推進」, 日本学術会議物理学委員会素粒子物
理学・原子核物理学分科会, 東京大学, 2022 年 9 月.

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Nuclear Science and Transmutation Research Division
Radioactive Isotope Physics Laboratory
1. Abstract

This Laboratory works as one of core research groups conducting programs at the world-premiere heavy-ion accelerator facilityof RIKEN “RI Beam Factory (RIBF).” The Laboratory explores exotic nuclear structures and dynamics in exotic nuclei that havenever been investigated before, such as those with largely imbalanced proton and neutron numbers. Our aim is to develop new
experimental techniques utilizing fast radioactive isotope (RI) beams at RIBF, to discover new phenomena and properties in exotic
nuclei. The Laboratory is focusing three major subjects; shell evolution of very neutron-rich nuclei, the r-process path and equationof-state in asymmetric nuclear matter. The Laboratory has initiated international collaborations for in-beam gamma spectroscopy,
decay spectroscopy and heavy-ion induced reactions, and has formed a discussion forum for next generation gamma-ray detectors.

2. Major Research Subjects(1) Study of structure and dynamics of exotic nuclei through developments of new tools in terms of reaction- and technique-based
methodology(2) Research on EOS in asymmetric nuclear matter via heavy-ion induced reactions(3) Detector developments for spectroscopy and reaction studies

3. Summary of Research Activity(1) In-beam gamma spectroscopy
In the medium and heavy mass region explored at RIBF, collective natures of nuclei are one of important subjects, which are
obtained through production and observation of high excited and high spin states. To populate such states, heavy-ion induced reactions
such as fragmentation, ﬁssion are useful. So far, we have developed two-step fragmentation method as an eﬃcient method to identify
and populate excited states, and lifetime measurements to deduce transition strength.
Devices utilized for the in-beam gamma spectroscopy are ZeroDegree spectrometer (ZDS) and a NaI array DALI2. Since the endof 2008, the ﬁrst spectroscopy on nuclei island-of-inversion region was performed, we have explored step-by-step new and unknown
regions in the nuclear chart. The second campaign in 2009 was organized to study background components originating from atomic
processes in a heavy target. Neutron-rich nuclei at N = 20 to 28 were studied in 2010. In 2011–2013, we conducted experiment
programs for Ca-54, Ni-78, neutron-rich nuclei at N = 82 and neutron-deﬁcient nuclei at Z = 50.
A multitude of data obtained with inelastic, nucleon knock-out, fragmentation channels have been analyzed and published. In
2011–2013, collective natures of Mg-36, 38 and Si-42 were both published in PRL. Excited states ﬁrstly observed in Ca-54 werereported in Nature to demonstrate a new nuclear magic number of 34. Fragmentation reaction has been found eﬃcient for nuclei
with A > 100 and low-lying excited state in Pd-126 has been successfully observed and reported in PRC. In 2019, results of the ﬁrst
spectrosocpy of 40 Mg was published in PRL, to demonstrate the exotic structure which is very diﬀerent from in other neutron-rich Mg
isotopes.
To further strengthen the in-beam gamma spectroscopy at RIBF, we have proposed a new setup of MINOS + DALI2 to search
for the 1st excited states in even-even neutron-rich nuclei with Z ∼ 20 to 40. The program was submitted to the PAC 2013 as a
new category of proposal, “proposal for scientiﬁc program” and was S-ranked. A dedicated collaboration “SEASTAR” has been
established as a subset of in-beam gamma collaboration “SUNFLOWER.” The three campaigns were organized in 2014, 2015 and2017 to study very neutron-rich isotopes, and were very productive to access very neutron-rich nuclei such as Ar-52, Ca-56, Ni-78,
Kr-100, Zr-110. In 2019, the result of the ﬁrst spectroscopy of Ni-78 was published in Nature.
A new project of high resolution gamma spectroscopy with fast beams “HiCARI” was proposed at PAC 2018. MINIBALL andseveral Ge tracking detectors from Japan, Europe, the USA and Korea were 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 two workshops were organized in 2019, and the machine time of 43.5 days in total was approved at PAC 2019.
The experiments with the MINOS setup were canceled due to the travel diﬃculties of COVID-19 for French engineers. The 31.5days
experiments were successfully conducted in 2020 and 2021.
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

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RIKEN Accel. Prog. Rep. 56 (2023)

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.
The success of the ﬁrst decay-spectroscopy campaign stimulated to form a new large-scale collaboration “EURICA,” where a
twelve Euroball cluster array is coupled with the silicon-strip detectors to enhance gamma eﬃciency by a factor of 10. A construction
proposal of “EURICA” was approved in the PAC 2011, and the commissioning was successfully organized in spring 2012. Since
then, physics runs had been conducted for programs approved to survey nuclei of interest as many as possible, such as Ni-78, Pd-128,
Sn-100. The EURICA collaboration ﬁnished its physics programs in summer 2016. So far, 54 papers including 14 PRL’s and 13
PLB’s were published. One of the highlights is discovery of a seniority isomer in Pd-128, of which cascade gamma decay gives theenergy of ﬁrst excited state and robustness of N = 82 magic number, and the other is a half-life measurement for 110 neutron-richnuclei across the N = 82 shell gap, which shows implications for the mechanism and universality of the r-process path.
Beta-delayed neutron emission probability of medium and heavy neutron-rich nuclei is important to understand nuclear structure
and the r-process path. In 2013, a new collaboration “BRIKEN” has been established to form a He-3 detector array. A present
design of the array has neutron eﬃciency as high as 70% up to 3 MeV. The array was coupled with the AIDA silicon strip system.
A construction proposal was approved at the PAC 2013. The commissioning run was conducted in autumn 2016. The major physics
runs were conducted in 2017–2021. One of the recent highlights is “Beta-Delayed One and Two Neutron Probabilities Southeast of
Sn-132 and the Odd-Even Systematics in r-Process Nuclide Abundances,” published in PRL, 2022.
A new project “IDATEN” has been launched in 2021 to measure lifetime of excited states with a large size LaBr3 array, which
is formed by combination of FATIMA and Khala arrays. The construction proposal was submitted to PAC, 2021, and proposals with
IDATEN were evaluated at PAC, 2022. The project has been conducted under UK, Korea, China, and Japan.
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 ﬁrst three papers were published in 2020 and 2021. One of them, which was published in
PRL, has been ranked as the TOP 1% paper by WoS.
An international symposium “NuSYM” on nuclear symmetry energy was organized at RIKEN July 2010 to invite researchers
in three sub-ﬁelds, nuclear structure, nuclear reaction and nuclear astrophysics, and to discuss nuclear symmetry energy together.
Since then, the symposium series have been held every year and been useful to encourage theoretical works and to strengthen thecollaboration.
(4) Nucleon correlation and cluster in nuclei
Nucleon correlation and cluster in nuclei are matters of central focus in a “beyond mean-ﬁeld” picture. The relevant programswith in-beam gamma and missing-mass techniques are to depict nucleon condensations and correlations in nuclear media as a functionof density as well as temperature. Neutron-halo and -skin nuclei are objects to study dilute neutron matter at the surface. By changing
excitation energies in neutron-rich nuclei, clustering phenomena and role of neutrons are to be investigated.
In 2013, two programs were conducted at the SAMURAI spectrometer. One is related to proton-neutron correlation in the C-12
nucleus via p-n knockout reaction with a carbon target. The other is to search for a cluster state in C-16, which was populated via
inelastic alpha scattering. The data is being analyzed.
In 2018, a new project based on missing mass spectroscopy was launched to investigate an exotic cluster state in a very protonrich nucleus. The experiment was organized at GANIL with combination of RIKEN liquid hydrogen target CRYPTA and the MUST2
detector array.

Members
Director
Hiroyoshi SAKURAI
Senior Research Scientists
Pieter C. DOORNENBAL
Tadaaki ISOBE
Akihisa KOHAMA

Yoichi NAKAI
Shunji NISHIMURA

Research Scientist
Daisuke SUZUKI
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RIKEN Accel. Prog. Rep. 56 (2023)

Nobuya NISHIMURA
Special Postdoctoral Researchers
Martha Liliana CORTES SUA

Masaomi TANAKA

Postdoctoral Researchers
Shoya TANAKA
Phong VI

Zuxing YANG

International Program Associates
Ting GAO (University of Hong Kong)

Jinn Ming YAP (University of Hong Kong)

Special Temporary Research Scientist
Takashi ICHIHARA
Research Consultants
Masayasu ISHIHARA

Kenichi MATSUYANAGI

Senior Visiting Scientists
Shigeru KUBONO (Univ. of Tokyo)

Tetsuya MURAKAMI

Visiting Scientists
Nori AOI (Osaka Univ.)Frank BROWNE (CERN)
Hue M. BUI (Vietnam Academy of Sci. and Tech.)
Giordano CERIZZA (Michigan State Univ.)
Sidong CHEN (Univ. of York)Silvio CHERUBINI (Univ. of Catania)
Xiaohua FAN (Southwest Univ.)
Chaoyi FU (Univ. of Hong Kong)
Mitsunori FUKUDA (Osaka Univ.)
Byungsik HONG (Korea Univ.)
Kei IIDA (Kochi Univ.)
Natsumi IKENO (Tottori Univ.)
Takuji IZUMIKAWA (Niigata Univ.)
Takashi KISHIDA (Aoyama Gakuin Univ.)
Gabor KISS (Inst. for Nuclear Res. (ATOMKI))
Asahi KOHDA (Osaka Univ.)
Khiem LE (Vietnam Academy of Sci. and Tech.)
Xiaoyu LIU (Univ. of Hong Kong)

Byul MOON (The Inst. for Basic Sci. (IBS))
Yoshiharu MORI (Kyoto Univ.)
Evgueni NIKOLSKI (Kurchatov Inst.)
Daiki NISHIMURA (Tokyo City Univ.)
Takashi OHTSUBO (Niigata Univ.)
Hooi Jin ONG (IMP, CAS)
Akira ONO (Tohoku Univ.)
Naohiko OTSUKA (IAEA)
Kazuhiro OYAMATSU (Aichi Shukutoku Univ.)
Paer-Anders SOEDERSTROEM (IFIN-HH, Romania)
Ryo TANIUCHI (Univ. of York)Rensheng WANG (Soochow Univ.)
Yijie WANG (Tsinghua Univ.)
Hiroshi WATANABE (Beihang Univ.)
Kathrin WIMMER (GSI)
Jin WU (Brookhaven Nat’l Lab.)
Yasutaka YAMAMOTO (Osaka Univ.)

Visiting Researcher
Umesh GARG (JSPS)
Student Trainees
Mei AMITANI (Tokyo City Univ.)
Takamichi AOKI (Univ. of Tokyo)
Takumi AOKI (Univ. of Tokyo)
Linh BUI (Vietnam Atomic Energy Inst.)
Hiroaki FUKUSHIMA (Rikkyo Univ.)
Miki FUKUTOME (Osaka Univ.)
Jiseok KIM (Korea Univ.)
Yukiya KOBAYASHI (Niigata Univ.)
Kei KOKUBUN (Univ. of Tokyo)
Rurie MIZUNO (Univ. of Tokyo)
Nurhaﬁza MOHAMAD NOR (Osaka Univ.)

Yuki NAKAMURA (Tokyo City Univ.)
Thomas G. PARRY (Univ. of Surrey)
Yuhao QIN (Tsinghua Univ.)
Sora SUGAWARA (Tokyo City Univ.)
Ryo TAGUCHI (Osaka Univ.)
Hiroyuki TAKAHASHI (Tokyo City Univ.)
Kazuya TAKATSU (Niigata Univ.)
Gen TAKAYAMA (Osaka Univ.)
Takumi TOMIYAMA (Tokyo City Univ.)
Tik Tsun YEUNG (Univ. of Tokyo)
Boyuan ZHANG (Tsinghua Univ.)

Research Part-time Workers
Kiyomi ARAI
Mie DOI
Miki KANOU
Eiko MIZUMOTO

Noriko OKAYASU
Mayumi SAITOTsuneyo SUZUKI
Miyuki TAMABAYASHI- 241 -

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RIKEN Accel. Prog. Rep. 56 (2023)

List of Publications & Presentations
Publications[Original Papers]
M. Enciu, H. N. Liu, A. Obertelli, P. Doornenbal, F. Nowacki, K. Ogata, A. Poves, K. Yoshida, N. L. 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. G illibert, 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, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, P. J. Li,
B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Y. Park, D. Rossi, E. Sahin, P. -A. Soderstrom, D. Sohler,
S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti,“Extended p3/2 neutron orbital and the N = 32 shell closure in 52 Ca,” Phys. Rev. Lett. 129, 262501 (2022).
B. Moon, C. -B. Moon, A. Odahara, R. Lozeva, S. Nishimura, C. Yuan, F. Browne, P. Doornenbal, G. Lorusso, Z. Patel, S. Rice,
L. Sinclair, P. -A. Söderström, T. Sumikama, H. Watanabe, J. Wu, Z. Y. Xu, A. Yagi, D. S. Ahn, H. Baba, F. L. Bello Garrote, R. Daido,
J. M. Daugas, F. Didierjean, Y. Fang, N. Fukuda, B. Hong, E. Ideguchi, N. Inabe, T. Ishigaki, T. Isobe, H. S. Jung, D. Kameda,
I. Kojouharov, T. Komatsubara, T. Kubo, Y. K. Kwon, C. S. Lee, P. Lee, S. Morimoto, D. Murai, M. Niikura, H. Nishibata, I. Nishizuka,
H. Sakurai, Y. Shimizu, H. Suzuki, H. Takeda, K. Tshoo, and R. Yokoyama, “Gamow-teller decay of 142 Te to 142 I,” Phys. Rev. C 107,014311 (2023).
S. Iimura, M. Rosenbusch, A. Takamine, Y. Tsunoda, M. Wada, S. Chen, D. S. Hou, W. Xian, H. Ishiyama, S. Yan, P. Schury, H. Crawford,
P. Doornenbal, Y. Hirayama, Y. Ito, S. Kimura, T. Koiwai, T. M. Kojima, H. Koura, J. Lee, J. Liu, S. Michimasa, H. Miyatake,J. Y. Moon, S. Naimi, S. Nishimura, T. Niwase, A. Odahara, T. Otsuka, S. Paschalis, M. Petri, N. Shimizu, T. Sonoda, D. Suzuki,
Y. X. Watanabe, K. Wimmer, and H. Wollnik, “Study of the N = 32 and N = 34 shell gap for Ti and V by the ﬁrst high-precisionmultireﬂection time-of-ﬂight mass measurements at BigRIPS-SLOWRI,” Phys. Rev. Lett. 130, 012501 (2023).
M. Rosenbusch, M. Wada, S. Chen, A. Takamine, S. Iimura, D. Hou, W. Xian, S. Yan, P. Schury, Y. Hirayama, Y. Ito, H. Ishiyama,
S. Kimura, T. Kojima, J. Lee, J. Liu, S. Michimasa, H. Miyatake, J. Y. Moon, M. Mukai, S. Naimi, S. Nishimura, T. Niwase, T. Sonoda,
Y. X. Watanabe, and H. Wollnik, “The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN’s RIBF
facility,” Nucl. Instrum. Methods Phys. Res. A 1047, 167824 (2023).
J. Wu, S. Nishimura, P. -A. Söderström, A. Algora, J. J. Liu, V. H. Phong, Y. Q. Wu, F. R. Xu, J. Agramunt, D. S. Ahn, T. A. Berry,
C. G. Bruno, J. J. Bundgaard, R. Caballero-Folch, A. C. Dai, T. Davinson, I. Dillmann, A. Estrade, A. Fijalkowska, N. Fukuda, S. Go,
R. K. Grzywacz, T. Isobe, S. Kubono, G. Lorusso, K. Matsui, A. I. Morales, N. Nepal, S. E. A. Orrigo, B. C. Rasco, K. P. Rykaczewski,
H. Sakurai, Y. Shimizu, D. W. Stracener, T. Sumikama, H. Suzuki, J. L. Tain, H. Takeda, A. Tarifeño-Salvidia, A. Tolosa-Delgado,
M. Wolińska-Cicocka, and R. Yokoyama, “First observation of isomeric states in 111 Zr, 113 Nb, and 115 Mo,” Phys. Rev. C 106, 064328(2022).
V. H. Phong, S. Nishimura, G. Lorusso, T. Davinson, A. Estrade, O. Hall, T. Kawano, J. Liu, F. Montes, N. Nishimura, R. Grzywacz,
K. P. Rykaczewski, J. Agramunt, D. S. Ahn, A. Algora, J. M. Allmond, H. Baba, S. Bae, N. T. Brewer, C. G. Bruno, R. Caballero-Folch,
F. Calviño, P. J. Coleman-Smith, G. Cortes, I. Dillmann, C. Domingo-Pardo, A. Fijalkowska, N. Fukuda, S. Go,1 C. J. Griﬃn, J. Ha,
L. J. Harkness-Brennan, T. Isobe, D. Kahl, L. H. Khiem, G. G. Kiss, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, J. Liang, Z. Liu,
K. Matsui, K. Miernik, B. Moon, A. I. Morales, P. Morrall, N. Nepal, R. D. Page, M. Piersa-Silkowska, V. F. E. Pucknell, B. C. Rasco,
B. Rubio, H. Sakurai, Y. Shimizu, D. W. Stracener, T. Sumikama, H. Suzuki, J. L. Tain, H. Takeda, A. Tarifeño-Salvidia, A. TolosaDelgado, M. Wolińska-Cicocka, P. J. Woods, and R. Yokoyama, “β-delayed one and two neutron emission probabilities southeast of132
Sn and the odd-even systematics in r-process nuclide abundances,” Phys. Rev. Lett. 129, 172701 (2022).
G. G. Kiss, A. Vitéz-Sveiczer, Y. Saito, A. Tarifeño-Salvidia, M. Pallas, J. L. Tain, I. Dillmann, J. Agramunt, A. Algora, C. DomingoPardo, A. Estrade, C. Appleton, J. M. Allmond, P. Aguilera, H. Baba, N. T. Brewer, C. Bruno, R. Caballero-Folch, F. Calviño,
P. J. Coleman-Smith, G. Cortes, T. Davinson, N. Fukuda, Z. Ge, S. Go, C. J. Griﬃn, R. K. Grzywacz, O. Hall, A. Horváth, J. Ha,
L. J. Harkness-Brennan, T. Isobe, D. Kahl, T. T. King, A. Korgul, S. Kovács, R. Krücken, S. Kubono, M. Labiche, J. Liu, J. Liang,
M. Madurga, K. Miernik, F. Molina, A. I. Morales, M. R. Mumpower, E. Nacher, A. Navarro, N. Nepal, S. Nishimura, M. PiersaSilkowska, V. Phong, B. C. Rasco, B. Rubio, K. P. Rykaczewski, J. Romero-Barrientos, H. Sakurai, L. Sexton, Y. Shimizu, M. Singh,
T. Sprouse, T. Sumikama, R. Surman, H. Suzuki, T. N. Szegedi, H. Takeda, A. Tolosa, K. Wang, M. Wolińska-Cicocka, P. Woods,
R. Yokoyama, and Z. Xu, “Measuring the β-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the
nucleosynthesis yields in the rare-earth region,” Astrophys. J. 936, 107 (2022).
A. Vitéz-Sveiczera, A. Algoraa, A. I. Morales, B. Rubioa, G. G. Kiss, P. Sarrigurene, P. Van Isacker, G. de Angelis, F. Recchia,
S. Nishimura, J. Agramunt, V. Guadilla, A. Montaner-Pizá, S. E. A. Orrigo, A. Horváth, D. Napoli, S. Lenzi, A. Boso, V. H. Phong,
J. Wu, P. -A. Söderström l, T. Sumikama, H. Suzuki, H. Takeda, D. S. Ahn, H. Baba, P. Doornebal, N. Fukuda, N. Inabe, T. Isobe,
T. Kubo, S. Kubono, H. Sakurai, Y. Shimizu, C. Sidong, B. Blank, P. Ascher, M. Gerbaux, T. Goigoux, J. Giovinazzo, S. Grévy,
T. Kurtukián Nieto, C. Magron, W. Gelletly, Zs. Dombrádi, Y. Fujita, M. Tanaka, P. Aguilera, F. Molina, J. Eberth, F. Diel, D. Lubos,
C. Borcea, E. Ganioglu, D. Nishimura, H. Oikawa, Y. Takei, S. Yagi, W. Korten, G. de France, P. Davies, J. Liu, J. Lee, T. Lokotko,
I. Kojouharov, N. Kurz, H. Shaﬀner, and A. Petrovici, “The β-decay of 70 Kr into 70 Br: Restoration of the pseudo-SU(4) symmetry,”
Phys. Lett. B 830, 137123 (2022).
V. Girard Alcindor, A. Mercenne, I. Stefan, F. de Oliveira Santos, N. Michel, M. Ploszajczak, M. Assie, A. Lemasson, E. Clement,
F. Flavigny, A. Matta, D. Ramos, M. Rejmund, J. Dudouet, D. Ackermann, P. Adsley, M .Assuncao, B. Bastin, D. Beaumel, G. Benzoni,
R. Borcea, A. J. Boston, D. Brugnara, L. Caceres, B. Cederwall, I. Celikovic, V. Chudoba, M. Ciemala, J. Collado, F. C. L. Crespi,
G. D’Agata, G. De France, F. Delaunay, C. Diget, C. Domingo-Pardo, J. Eberth, C. Fougeres, S. Franchoo, F. Galtarossa, A. Georgiadou,
J. Gibelin, S. Giraud, V. Gonzalez, N. Goyal, A. Gottardo, J. Goupil, S. Grevy, V. Guimaraes, F. Hammache, L. J. Harkness-Brennan,
H. Hess, N. Jovancevic, D. S. Judson Oliver, O. Kamalou, A. Kamenyero, J. Kiener, W. Korten, S. Koyama, M. Labiche, L. Lalanne,- 242 -

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RIKEN Accel. Prog. Rep. 56 (2023)

V. Lapoux, S. Leblond, A. Lefevre, C. Lenain, S. Leoni, H. Li, A. Lopez-Martens, A. Maj, I. Matea, R. Menegazzo, D. Mengoni,
A. Meyer, B. Million, B. Monteagudo, P. Morfouace, J. Mrazek, M. Niikura, J. Piot, Zs. Podolyak, C. Portail, A. Pullia, B. Quintana,
F. Recchia, P. Reiter, K. Rezynkina, T. Roger, J. S. Rojo, F. Rotaru, M. D. Salsac, A. M. Sanchez-Benitez, E. Sanchis, M. Senyigit,
N. de Sereville, M. Siciliano, J. Simpson, D. Sohler, O. Sorlin, M. Stanoiu, C. Stodel, D. Suzuki, C. Theisen, D. Thisse, J. C. Thomas,
P. Ujic, J. J. Valiente-Dobon, and M. Zielinska, “New narrow resonances observed in the unbound nucleus 15 F,” Phys. Rev. C 105,
L051301 (2022).
L. Lalanne, O. Sorlin, A. Poves, M. Assié, F. Hammache, S. Koyama, D. Suzuki, F. Flavigny, V. Girard-Alcindor, A. Lemasson, A. Matta,
T. Roger, D. Beaumel, Y. Blumenfeld, B. A. Brown, F. De Oliveira Santos, F. Delaunay, N. de Séréville, S. Franchoo, J. Gibelin,
J. Guillot, O. Kamalou, N. Kitamura, V. Lapoux, B. Mauss, P. Morfouace, M. Niikura, J. Pancin, T. Y. Saito, C. Stodel, and J. C. Thomas, “Structure of 36 Ca under the coulomb magnifying glass,” Phys. Rev. Lett. 129, 122501 (2022).
B. Le Crom, M. Assié, Y. Blumenfeld, J. Guillot, H. Sagawa, T. Suzuki, M. Honma, N. L. Achouri, B. Bastin, R. Borcea, W. N. Catford,
E. Clément, L. Caceres, M. Caamano, A. Corsi, G. De France, F. Delaunay, N. De Séréville, B. Fernandez-Dominguez, M. Fisichella,
S. Franchoo, A. Georgiadou, J. Gibelin, A. Gillibert, F. Hammache, O. Kamalou, A. Knapton, V. Lapoux, S. Leblond, A. O. Macchiavelli, F. M. Marques, A. Matta, L. Ménager, P. Morfouace, N. A. Orr, J. Pancin, X. Pereira-Lopez, L. Perrot, J. Piot, E. Pollacco,
D. Ramos, T. Roger, F. Rotaru, A. M. Sánchez-Benı́tez, M. Sénoville, O. Sorlin, M. Stanoiu, I. Stefan, C. Stodel, D. Suzuki, J. C. Thomas, M. Vandebrouck, “Neutron-proton pairing in the N = Z radioactive fp-shell nuclei 56 Ni and 52 Fe probed by pair transfer,”
Phys. Lett. B 829, 137057 (2022).
L. Zago, A. Gottardo, J. J. Valiente-Dobon, G. Benzoni, A. Gadea, M. Gorska, S. Lunardi, Zs. Podolyak, P. H. Regan, D. Rudolph,
A. Algora, G. de Angelis, D. Bazzacco, J. Benlliure, P. Boutachkov, A. Bracco, A. M. Bruce, F. Camera, E. Casarejos, M. L. Cortes,
F. C. L. Crespi, A. Corsi, C. Domingo-Pardo, M. Doncel, T. Engert, H. Geissel, J. Gerl, A. Goasduﬀ, N. Goel, J. Grebosz, E. Gregor, T. Habermann, S. Klupp, I. Kojouharov, N. Kurz, S. M. Lenzi, S. Leoni, S. Mandal, R. Menegazzo, D. Mengoni, B. Million,
A. I. Morales, D. R. Napoli, F. Naqvi, C. Nociforo, M. Pfutzner, S. Pietri, A. Prochazka, F. Recchia, E. Sahin, H. Schaﬀner, A. Sharma,
B. Sitar, D. Siwal, P. Strmen, I. Szarka, C. A. Ur, P. M. Walker, H. Weick, O. Wieland, H. -J. Wollersheim, “High-spin states in 212 Po
above the α-decaying (18+ ) isomer,” Phys. Lett B 834, 137457 (2022).
S. M. Cha, K. Y. Chae, K. Abe, S. Bae, D. N. Binh, S. H. Choi, N. N. Duy, Z. Ge, K. I. Hahn, S. Hayakawa, B. Hong, N. Iwasa, D. Kahl,
L. H. Khiem, A. Kim, D. Kim, E. J. Kim, G. W. Kim, M. J. Kim, K. Kwak, M. S. Kwag, E. J. Lee, S. I. Lim, B. Moon, J. Y. Moon,
S. Y. Park, V. H. Phong, H. Shimizu, H. Yamaguchi, and L. Yang, “Investigation of 22 Mg levels via resonant scattering of 22 Ne+α,”
Front. Phys. 11, 375 (2023).
X. -H. Fan, Z. -X. Yang, P. Yin, P. -H. Chen, J. -M. Dong, Z. -P. Li, and H. Liang, “A local-density-approximation description of highmomentum tails in isospin asymmetric nuclei,” Phys. Lett. B 834, 10 (2022).
P. -H. Chen, H. Wu, Z. -X. Yang, X. -H. Zeng, Z. -Q. Feng, “Prediction of synthesis cross sections of new moscovium isotopes infusion-evaporation reactions,” Nucl. Sci. Tech. 34, 7 (2023).
Z. -X. Yang, X. -H. Fan, Z. -P. Li, and H. Liang, “A Kohn-Sham scheme based neural network for nuclear systems,” Phys. Lett. B 840, 10(2023).
W. P. Liu, Z. H. Li, J. J. He, X. D. Tang, G. Lian, J. Su, Y. P. Shen, Z. An, F. Q. Chao, J. J. Chang, L. H. Chen, H. Chen, X. J. Chen, Y. H.
Chen, Z. J. Chen, B. Q. Cui, X. C. Du, X. Fang, C. B. Fu, L. Gan, B. Guo, Z. Y. Han, X. Y. Guo, G. Z. He, J. R. He, A. Heger, S. Q.
Hou, H. X. Huang, N. Huang, B. L. Jia, L. Y. Jiang, S. Kubono, J. M. Li, M. C. Li, K. A. Li, E. T. Li, T. Li, Y. J. Li, M. Lugaro, X. B.
Luo, H. Y. Ma, S. B. Ma, D. M. Mei, W. Nan, W. K. Nan, N. C. Qi, Y. Z. Qian, J. C. Qin, J. Ren, C. S. Shang, L. T. Sun, W. L. Sun,
W. P. Tan, I. Tanihata, S. Wang, P. Wang, Y. B. Wang, Q. Wu, S. W. Xu, S. Q. Yan, L. T. Yang, Y. Yang, X. Q. Yu, Q. Yue, S. Zeng, L.
Zhang, H. Zhang, H. Y. Zhang, L. Y. Zhang, N. T. Zhang, P. Zhang, Q. W. Zhang, T. Zhang, X. P. Zhang, X. Z. Zhang, W. Zhao, J. F.
Zhou, and Y. Zhou, “Progress of underground nuclear astrophysics experiment JUNA in China,” Few-Body Syst. 63, 43 (2022).
Y. H. Lam, N. Lu, A. Heger, A. M. Jacobs Nadezda, A. Smirnova, T. K. Nieto, Z. Johnston, and S. Kubono, “The regulated NiCu cycles
with the new 57 Cu(p, γ)58 Zn reaction rate and its inﬂuence on type I X-ray bursts: the GS 1826–24 clocked burster,” Astrophys. J. 929,
73 (2022).
B. Gao, T. Y. Jiao, Y. T. Li, H. Chen, W. P. Lin, Z. An, L. H. Ru, Z. C. Zhang, X. D. Tang, X. Y. Wang, N. T. Zhang, X. Fang, D. H. Xie,
Y. H. Fan, L. Ma, X. Zhang, F. Bai, P. Wang, Y. X. Fan, G. Liu, H. X. Huang, Q. Wu, Y. B. Zhu, J. L. Chai, J. Q. Li, L. T. Sun,
S. Wang, J. W. Cai, Y. Z. Li, J. Su, H. Zhang, Z. H. Li, Y. J. Li, E. T. Li, C. Chen, Y. P. Shen, G. Lian, B. Guo, X. Y. Li, L. Y. Zhang,
J. J. He, Y. D. Sheng, Y. J. Chen, L. H. Wang, L. Zhang, F. Q. Cao, W. Nan, W. K. Nan, G. X. Li, N. Song, B. Q. Cui, L. H. Chen,
R. G. Ma, Z. C. Zhang, S. Q. Yan, J. H. Liao, Y. B. Wang, S. Zeng, D. Nan, Q. W. Fan, N. C. Qi, W. L. Sun, X. Y. Guo, P. Zhang,
Y. H. Chen, Y. Zhou, J. F. Zhou, J. R. He, C. S. Shang, M. C. Li, S. Kubono, and W. P. Liu, “Deep underground laboratory measurementof 13 C(α, n)16 O in the gamow windows of the s and i processes,” Phys. Rev. Lett. 129, 132701 (2022).
A. Miyazaki, M. Tsuge, H. Hidaka, Y. Nakai, and N. Watanabe, “Direct determination of the activation energy for diﬀusion of OH radicals
on water ice,” Astrophys. J. Lett. 940, L2 (2022).

[Proceedings]
M. Pallas, A. Tarifeno-Saldivia, G. G. Kiss, J. L. Tain, A. Tolosa-Delgado, A. Vitez-Sveiczer, F. Calvino, J. Agramunt, P. Aguilera,
A. Algora, J. M. Allmond, H. Baba, N. T. Brewer, R. Caballero-Folch, P. J. Coleman-Smith, G. Cortes, T. Davinson, I. Dillmann,
C. Domingo-Pardo, A. Estrade, N. Fukuda, S. Go, C. J. Griﬃn, R. K. Grzywacz, O. Hall, L. J. Harkness-Brennan, T. Isobe, D. Kahl,
T. T. King, A. Korgul, S. Kovacs, S. Kubono, M. Labiche, J. Liu, M. Madurga, K. Miernik, F. Molina, N. Mont-Geli, A. I. Morales,
E. Nácher, A. Navarro, N. Nepal, S. Nishimura, M. Piersa-Silkowska, V. Phong, B. C. Rasco, J. Romero-Barrientos, B. Rubio,
K. P. Rykaczewski, Y. Saito, H. Sakurai, Y. Shimizu, M. Singh, T. Sumikama, H. Suzuki, T. N. Szegedi, H. Takeda, K. Wang,
M. Wolińska-Cichocka, P. J. Woods, R. Yokoyama and for the BRIKEN Collaboration, “Study of decay properties of Ba to Nd nuclei(A ≈ 160) relevant to the formation of the r-process rare-earth peak,” EPJ Web Conf. 284, 02005 (2023).
H. Yamaguchi, S. Hayakawa, N. Ma, H. Shimizu, K. Okawa, Q. Zhang, L. Yang, D. Kahl, M. La Cognata, L. Lamia, K. Abe, O. Be-- 243 -

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liuskina, S. Cha, K. Chae, S. Cherubini, P. Figuera, Z. Ge, M. Gulino, J. Hu, A. Inoue, N. Iwasa, A. Kim, D. Kim, G. Kiss, S. Kubono,
M. La Commara, M. Lattuada, E. Lee, J. Moon, S. Palmerini, C. Parascandolo, S. Park, V. Phong, D. Pierroutsakou, R. Pizzone,
G. Rapisarda, S. Romano, C. Spitaleri, X. Tang, O. Trippella, A. Tumino, N. Zhang, Y. Lam, A. Heger, A. Jacobs, S. Xu, S. Ma, L. Ru,
E. Liu, T. Liu, C. Hamill, A. S. J. Murphy, J. Su, X. Fang, M. Kwag, N. Duy, N. Uyen, D. Kim, J. Liang, A. Psaltis, M. Sferrazza,
Z. Johnston, and Y. Li, “RIB induced reactions: Studying astrophysical reactions with low-energy RI beam at CRIB,” EPJ Web Conf.
275, 01015 (2023).
S. Tanaka, N. Nishimura, I. Nishimura, and Y. Aritomo, “The evaluation of the ﬁssion mode and fragment yields of neutron-rich nucleiby
the ynamical model,” EPJ Web Conf. 279, 11021 (2023).

Presentations[International Conferences/Workshops]
H. Sakurai (invited), “Neutron-rich nuclei, a treasure-chest of discovery and application,” The 28th International Nuclear Physics Conference (INPC 2022), Cape Town, South Africa, September 11–16, 2022.
H. Sakurai (invited) “Recent progress and plans at RIBF,” Pioneer symposium in Korean Physical Society, Hybrid, April 21, 2022.
H. Sakurai (invited) “Recent progress and plans at RIBF,” CPS-APS-IOP-JPS-DPG Joint Session on Large-Scale Facilities for Science inChinese Physical Society, Hybrid, November 18–22, 2022.
S. Nishimura (invited), “Dense matter from nuclear reactions in astro- and heavy-ion physics,” Intersection of Nuclear Structure andHigh-Energy Nuclear Collisions, Washington University (INT), Seattle, USA, January 23–27, 2023.
S. Nishimura (invited), “Exotic nuclei: Toward the dripline,” Nuclear Physics in Astrophysics -X, CERN, Geneva, Switzerland, September
4–9, 2022.
S. Nishimura (invited), “Experiments Relevant to r-Process Nucleosynthesis,” The 15th Asian Paciﬁc Physics Conference (APPC15),
August 21–26, 2022.
S. Nishimura (invited), “Experiments related to r-process nucleosynthesis,” Mean-ﬁeld and Cluster Dynamics in Nuclear Systems 2022
(MCD2022), May 9–June 17, 2022.
P. Doornenbal (invited), “First Spectroscopy of 56, 58 Ca,” Reimei Workshop, Darmstadt, Germany, October 10–12, 2022.
D. Suzuki (invited), “Spectroscopy of 8 C: mirror symmetry beyond the proton drip line,” Halo Week 2022, Bergen, Norway, July 20–15,
2022.
M. L. Cortés (invited), “In-beam gamma-ray spectroscopy towards 100 Sn: Recent results and future perspectives” Reimei workshop on“Unveiling nuclear shells and correlations in exotic nuclei through knockout reactions,” TU Darmstadt, Germany, October 9–11, 2022.
Y. Nakai (poster), W. M. C. Sameera, K. Furuya, H. Hidaka, A. Ishibashi, and N. Watanabe, “Methanol production through irradiation of
low-energy CH3 + ions on a water ice surface,” Symposium on Next Generation Astrochemistry, Tokyo, Japan, November 29–December
2, 2022.
V. H. Phong (invited), “Experimental studies of the β-decay properties among other important nuclear data inputs for the r-process
nucleosynthesis at the RIKEN RIBF,” International Symposium on Origin of Matter and Evolution of Galaxies OMEG16 2022, Hanoi,
Vietnam, October 24–28, 2022.
V. H. Phong (oral), “Beta-delayed one and two neutron emission probabilities south-east of 132 Sn : Impact on the odd-even abundance
pattern of the second r-process peak,” UKAKUREN-RCNP Conference on AstroNuclear Physics ANP2022, Osaka, Japan, July 20–21,
2022.
V. H. Phong (oral), “Beta-Delayed Neutron-Emission Probabilities of 20 neutron-rich Ag, Cd, In and Sn isotopes: Impacts on the second
r-process peak formation,” Astrophysics with Radioactive Isotopes 2022, Budapest, Hungary, June 12–17, 2022.
V. H. Phong (oral), “20 β-delayed neutron emission probabilities across the Z = 50 and N = 82 shell closure: Implication on the formationof the second r-process peak,” International Nuclear Physics Conference (INPC) 2022, Cape Town, South Africa, September 11–16,
2022.
Y. Aritomo (poster), S. Tanaka, N. Nishimura, and I. Nishimura, “The evaluation of the ﬁssion mode and fragment yields of neutron-richnuclei by the dynamical model,” Nuclear Physics in Astrophysics-X, Geneva, Switzerland, September 5–9, 2022.
F. Minato (poster), S. Tanaka, and N. Nishimura, “Fission fragment yields of neutron-rich nuclei evaluated by the Langevin model
calculation,” 2022 Symposium on Nuclear Data, Osaka, Japan, November 17–18, 2022.

[Domestic Conferences/Workshops]

西村俊二（招待講演）, 「中性子捕獲反応と元素合成: 鍵を握る原子核データの収集と研究戦略」, 中性子捕獲反応で迫る宇宙の元
素合成, 東京大学本郷キャンパス, 2023 年 2 月 9–10 日.
鈴木大介（一般講演）, 「非束縛核 8 C におけるミラー対称性の研究」, 2022 年日本物理学会秋季大会, 岡山県岡山市 (岡山理科大学),
2022 年 9 月 6–8 日.
鈴木大介（招待講演）, 「RI ビームファクトリーにおける超新星爆発下の核反応研究」, 中性子捕獲反応で迫る宇宙の元素合成, 東京都文京区 (東京大学), 2023 年 2 月 9–10 日.
鈴木大介（招待講演）, 「RI ビームを用いた高速陽子捕獲反応の研究」, 星の進化と爆発天体における核反応の物理, 埼玉県和光市(理化学研究所), 2023 年 2 月 20–21 日.
中井陽一 (口頭発表）, 「低エネルギーイオンと低温氷表面との反応」, 文科省科研費 学術変革領域（A）次世代アストロケミスト
リー 気相実験ワークショップ, 宮崎県宮崎市 (KITEN ビルコンベンションホール), 2022 年 9 月 7 日.
中井陽一 (口頭発表）, 日高宏, 渡部直樹, 「低エネルギーイオンと氷表面との反応実験」, 日本物理学会 2022 年秋季大会, 東京都目
黒区 (東京工業大学), 2022 年 9 月 12–15 日.

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中井陽一 (口頭発表）, 「低エネルギーイオンと極低温氷表面との分子生成反応」, 学術変革領域次世代アストロケミストリー 第 3
回 領域全体集会, 東京都文京区 (東京大学), 2022 年 3 月 7–9 日.
中井陽一 (口頭発表）, 渡部直樹, 柘植雅士, 副島浩一, 「極低温氷表面に存在する OH ラジカルの可視域光による光脱離」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
P. Doornenbal (invited), “Past achievements and future perspectives for in-beam gamma-ray spectroscopy at the isospin frontier at the
RIBF,” Physics of RI: Recent progress and perspectives workshop, Wako, Japan, May 30–June 1, 2022.
M. L. Cortés (invited), “In-beam gamma-ray spectroscopy towards 100 Sn: Recent results and future perspectives” RIBF Users Meeting
2022, RIBF, RIKEN, Japan, September 20–22, 2022.
有友嘉浩 (口頭発表), 田中翔也, 西村信哉, 西村絃志, 「r プロセス計算へ向けた動力学模型による核分裂研究」, 日本物理学会 2022
年秋季大会, 岡山県岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
湊太志 (ポスター), 田中翔也, 西村信哉, 「r プロセス計算へ向けた中性子過剰核領域における核分裂収率の理論評価」, 2022 (令和4) 年度 国立天文台 CfCA ユーザーズミーティング, 東京都三鷹市 (国立天文台), 2023 年 1 月 26–27 日.
有友嘉浩 (口頭発表), 田中翔也, 西村信哉, 湊太志, 西村絃志, 「r プロセス計算へ向けた核分裂の評価」, [RIBF-ULIC-miniWS038]
理論と実験で拓く中性子過剰核の核分裂, 東京都和光市 (理化学研究所), 2023 年 2 月 16–17 日.
有友嘉浩 (口頭発表), 田中翔也, 西村信哉, 西村絃志, 湊太志, 「動力学模型による中性子過剰核の核分裂収率計算」, 日本原子力学会 2023 年春の年会, 東京都目黒区 (東京大学), 2023 年 3 月 13–15 日.
湊太志 (口頭発表), 田中翔也, 西村信哉, 「ランジュバン計算と統計模型を用いた核分裂収率および即発中性子の評価」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.

[Seminars]

D. Suzuki (invited), “Radioactive isotope physics,” INTPART School 2023, Okinawa, Japan, February 20–March 3, 2023.
P. Doornenbal, “Latest Results and Future Potential for In-Beam γ-Ray Spectroscopy at the RIBF,” SFB Seminar, Darmstadt, Germany,
May 19, 2022.
田中翔也, 「動力学模型による核分裂の理論計算」, 第 57 回「基礎科学セミナー」, 千葉県習志野市 (千葉工業大学), 2023 年 2 月
25 日.

Press Releases

極低温氷表面での OH ラジカルの動きやすさを初めて測定—宇宙の氷微粒子上で分子進化が活性化する温度が明らかに—, 北海道大学, 理化学研究所, 2022 年 11 月 24 日, https://www.riken.jp/press/2022/20221124_1/index.html .
加速器実験による r 過程の同位体比の再現に成功—宇宙初期と太陽系のバリウムは中性子星合体が起源か？ — 2022 年 10 月 19
日, https://www.riken.jp/press/2022/20221019_1/index.html .

AwardsP. Doornenbal, Friedrich Wilhelm Bessel Research Award, 2022.
水野るり惠, 放射線化学討論会, 優秀発表賞 (学生), 2022 年 9 月.

Outreach Activities

櫻井博儀,「理研で進展する元素変換科学—宇宙での元素進化—」, 埼玉県立春日部高等学校, 2023 年 2 月.
櫻井博儀, 2022 年度「はかる! 」, 埼玉県立不動岡高等学校.

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RIKEN Accel. Prog. Rep. 56 (2023)

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- 246 -

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RIKEN Accel. Prog. Rep. 56 (2023)

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
corre- sponding to ground and excited levels in 12 Be have been clearly observed. Another double charge exchange reaction, (12 C,
12Be(0+ )) are being used to search for double Gamow-Teller resonances.
(3) r-process nucleosynthesis study with heavy-ion storage ring
Most of the r-process nuclei become within reach of experimental studies for the ﬁrst time at RI Beam Factory at RIKEN. The
Rare RI Ring at RIBF is the unique facility with which we can perform mass measurements of r-process nuclei. Construction of theRare RI Ring started in FY2012 in collaboration with Tsukuba and Saitama Universities. A major part of the ring has been completed
and the commissioning run is planned in FY2014.
We are planning to start precise mass measurements of r-process nuclei soon. A series of experiments will start with nuclei in the
A = 80 region and will be extended to heavier region.
(4) Application of spin-polarization technique to RI-beam experiments and other ﬁelds
A technique to produce nuclear polarization by means of electron polarization in photo-excited triplet states of aromatic molecules
can open new applications. The technique is called “Tripletd-DNP.” A distinguished feature of Triplet-DNP is that it works under alow magnetic ﬁeld of 0.1–0.7 T and temperature higher than 100 K, which exhibits a striking contrast to standard dynamic nuclear
polarization (DNP) techniques working in extreme conditions of several Tesla and sub-Kelvin.
We have constructed a polarized proton target system for use in RI-beam experiments. Recent experimental and theoretical studies
have revealed that spin degrees of freedom play a vital role in exotic nuclei. Tensor force eﬀects on the evolution of shell and possible
occurrence of p-n pairing in the proton-rich region are good examples of manifestations of spin degrees of freedom. Experimentswith the target system allow us to explore the spin eﬀects in exotic nuclei. It should be noted that we have recently achieved a proton
polarization of 40% at room temperature in a pentacene-d14 doped p-terphenyl crystal.
Another interesting application of Triplet-DNP is sensitivity enhancement in NMR spectroscopy of biomolecules. We started a
new project to apply the Triplet-DNP technique to study protein-protein interaction via two-dimensional NMR spectroscopy, in close
collaboration with biologists and chemists.
(5) Development of special targets for RI-beam experiments
For the research activities shown above, we are developing and hosting special targets for RI-beam experiments listed below:(a) Polarized proton target (described in (4))(b) Thin solid hydrogen target(c) MINOS (developed at Saclay and hosted by the Spin Isospin Laboratory)

Members
Director
Tomohiro UESAKA
Senior Research Scientists
Masaki SASANO
Ken-ichiro YONEDA

Juzo ZENIHIRO

Research Scientists
Sarah NAIMI

Kenichiro TATEISHI

Research & Development Scientist
Yohei SHIMIZU
Postdoctoral Researcher
Junki TANAKA
Junior Research Associates
Shutaro HANAITomoya HARADAInternational Program Associates
Siwei HUANG

Yutian LI

Research Consultants
Harutaka SAKAGUCHI (Osaka Univ.)
Yasuyuki SUZUKI

Kazuko TANABE- 247 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Senior Visiting Scientist
Hiroyuki SAGAWA (Univ. of Aizu)
Visiting Scientists
Satoshi ADACHI (Osaka Univ.)
Hidetoshi AKIMUNE (Konan Univ.)
Didier BEAUMEL (Inst. de Phys.Nucl.)
Konstanze BORETZKY (GSI)
Anna CORSI (CEA Saclay)
Masanori DOZONO (Kyoto Univ.)
Zoltan ELEKES (ATOMKI)
Zsolt FULOP (ATOMKI)
Tatsuya FURUNO (Osaka Univ.)
Igor GASPARIC (Rudjer Boskovic Inst.)
Valdir GUIMARAES (Inst.o de Fisica da Univ. de Sao Paulo)
Zoltan HALASZ (ATOMKI)
Kaori KAKI (Shizuoka Univ.)
Takahiro KAWABATA (Osaka Univ.)
Yuma KIKUCHI (NIT, Tokuyama College)
Yosuke KONDO (Tokyo Tech)
Zeren KORKULU (Inst. for Basic Sci. (IBS))
Attila KRASZNAHORKAY (ATOMKI)
Dorottya KUNNE SOHLER (ATOMKI)
Istvan KUTI (ATOMKI)
Valerie LAPOUX (Inst.ion CEA-Saclay)
Yury LITVINOV (GSI)
Hongna LIU (TU Darmstadt)
Yohei MATSUDA (Konan Univ.)

Kenjiro MIKI (Tohoku Univ.)
Tetsuaki MORIGUCHI (Tsukuba Univ.)
Sarah NAIMI (IJCLab (Laboratoire de physique des 2 inﬁnis Irene Joliot-Curie))
Takashi NAKAMURA (Tokyo Tech)
Noritsugu NAKATSUKA (Tokyo Tech)Alexandre OBERTELLI (TU Darmstadt)
Kazuyuki OGATA (Osaka Univ.)
Valerii PANIN (GSI)
Aldric REVEL (CEA Saclay)
Kimiko SEKIGUCHI (Tokyo Tech)
Laszlo STUHL (Inst. for Basic Sci. (IBS))
Baohua SUN (Beihang Univ.)
Yelei SUN (TU Darmstadt)
Shinji SUZUKI (Chinese Academy of Sci.)
Satoru TERASHIMA (Beihang Univ.)
Yasuhiro TOGANO (Rikkyo Univ.)
Takashi WAKUI (QST)
Atomu WATANABE (JSPS)
Takayuki YAMAGUCHI (Saitama Univ.)
Zaihong YANG (Osaka Univ.)
Juzo ZENIHIRO (Kyoto Univ.)
Yuhu ZHANG (IMP, CAS)

Visiting Technicians
Denis CALVET (CEA)
Alain DELBART (CEA/CE Saclay)
Clement HILAIRE (CEA Saclay)

Shoji SUZUKI (KEK)
Olivier TELLIER (CEA Saclay)

Student Trainees
Tomoki ADACHI (Kyushu Univ.)
Sota ANDO (Kyushu Univ.)
Paul ANDRE (CEA Saclay)
Naoki EBINA (Tokyo Tech)
Shiyo EN’YO (Kyoto Univ.)
Yuki FUJIKAWA (Kyoto Univ.)
Saiya FUJIWARA (Kyushu Univ.)
Jian GAO (Peking Univ.)
Shutaro HANAI (Univ. of Tokyo)
Sakumi HARAYAMA (Saitama Univ.)
Koshi HIGUCHI (Saitama Univ.)
Kouta HORIKAWA (Tokyo Tech)
Kento INABA (Kyoto Univ.)
Kakeru ISOBE (Tokyo Tech)
Koki KAMEYA (Tohoku Univ.)
Naoto KANAME (Tsukuba Univ.)
Masanori KANDA (Saitama Univ.)
Fumiya KAWAGUCHI (Tokyo Tech)
Yusuke KAWASHIMA (Kyushu Univ.)
Kanki KISHIMOTO (Kyushu Univ.)
Sho KITAYAMA (Tohoku Univ.)
Yukari KOIZUMI (Saitama Univ.)
Hyeji LEE (Tokyo Tech.)
Hongfu LI (IMP, CAS)

Yoshiki MARUTA (Tohoku Univ.)
Takaya MATSUI (Tohoku Univ.)
Tomoki MATSUI (Tokyo Tech)
Riku MATSUMURA (Saitama Univ.)
Atsuyuki MORIYAMA (Tsukuba Univ.)
Shintaro OKAMOTO (Kyoto Univ.)
Kengo OKUBO (Saitama Univ.)
Misaki OTSU (Saitama Univ.)
Yuko SAITO (Tohoku Univ.)
Kosuke SAKANASHI (Osaka Univ.)
Kenta SASAKI (Saitama Univ.)
Hibiki SEKI (Saitama Univ.)
Yusuke SHINOHARA (Kyushu Univ.)
Naru SHINOZAKI (Saitama Univ.)
Kohei TAKAHASHI (Tokyo Tech)Ryotaro TSUJI (Kyoto Univ.)
Ren URAYAMA (Tohoku Univ.)
Kanta YAHIRO (Kyoto Univ.)
Kohei YAMAMOTO (Tohoku Univ.)
Wataru YAMASHITA (Kyushu Univ.)
Asahi YANO (Tsukuba Univ.)
Nozomi YOKOTA (Kyushu Univ.)
Chieko YONEMURA (Kyushu Univ.)
Ryohsuke YOSHIDA (Kyoto Univ.)- 248 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Assistants
Emiko ISOGAI

Yuri TSUBURAI

List of Publications & Presentations
Publications[Original Papers]
V. P. Ladygin, A. V. Averyanov, E. V. Chernykh, D. Enache, Yu. V. Gurchin, A. Yu. Isupov, M. Janek, J. -T. Karachuk, A. N. hrenov,
D. O. Krivenkov, P. K. Kurilkin, N. B. Ladygina, A. N. Livanov, O. Mezhenska, S. M. Piyadin, S. G. Reznikov, Y. T. Skhomenko,
A. A. Terekhin, A. V. Tishevsky, T. Uesaka, and I. S. Volkov, “Deuteron analyzing powers Ay , Ayy , and A xx in d p-elastic scattering atlarge transverse momenta,” JPS Conf. Proc. 37, 020902 (2022).
T. Aumann, W. Bartmann, O. Boine-Frankenheim, A. Bouvard, A. Broche, F. Butin, D. Calvet, J. Carbonell, P. Chiggiato, H. De Gersem,
R. De Oliveira, T. Dobers, F. Ehm, J. Ferreira Somoza, J. Fischer, M. Fraser, E. Friedrich, A. Frotscher, M. Gomez-Ramos, J. L. Grenard, A. Hobl, G. Hupin, A. Husson, P. Indelicato, K. Johnston, C. Klink, Y. Kubota, R. Lazauskas, S. Malbrunot-Ettenauer,
N. Marsic, W. F. O Müller, S. Naimi, N. Nakatsuka, R. Necca, D. Neidherr, G. Neyens, A. Obertelli, Y. Ono, S. Pasinelli, N. Paul,
E. C. Pollacco, D. Rossi, H. Scheit, M. Schlaich, A. Schmidt, L. Schweikhard, R. Seki, S. Sels, E. Siesling, T. Uesaka, M. Vilén,M. Wada, F. Wienholtz, S. Wycech, and S. Zacarias, “PUMA, antiProton unstable matter annihilation,” Eur. Phys. J. A 58, 88 (2022).
V. P. Ladygin, A. V. Averyanov, E. V. Chernykh, D. Enache, Y. V. Gurchi, 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, A. A. Terekhin, A. V. Tishevsky, T. Uesaka, and I. S. Volkov, “Angular dependences of the deuteron analyzing powers in elastic d p scattering at large transverse momenta,”
Phys. Part. Nucl. 53, 251 (2022).
M. Duer, T. Aumann, R. Gernhäuser, V. Panin, S. Paschalis, D. M. Rossi, N. L. Achouri, D. Ahn, H. Baba, C. A. Bertulani, M. Böhmer,
K. Boretzky, C. Caesar, N. Chiga, A. Corsi, D. Cortina-Gil, C. A. Douma, F. Dufter, Z. Elekes, J. Feng, B. Fernández-Domı́nguez,
U. Forsberg, N. Fukuda, I. Gasparic, Z. Ge, J. M. Gheller, J. Gibelin, A. Gillibert, K. I. Hahn, Z. Halász, M. N. Harakeh, A. Hirayama,
M. Holl, N. Inabe,T. Isobe, J. Kahlbow, N. Kalantar-Nayestanaki, D. Kim, S. Kim, T. Kobayashi, Y. Kondo, D. Körper, P. Koseoglou,
Y. Kubota, I. Kuti, P. J. Li, C. Lehr, S. Lindberg, Y. Liu,F. M. Marqués, S. Masuoka, M. Matsumoto, J. Mayer, K. Miki, B. Monteagudo,
T. Nakamura, T. Nilsson, A. Obertelli, N. A. Orr, H. Otsu, S. Y. Park, M. Parlog, P. M. Potlog, S. Reichert, A. Revel, A. T. Saito,
M. Sasano, H. Scheit, F. Schindler, S. Shimoura, H. Simon, L. Stuhl, H. Suzuki, D. Symochko, H. Takeda, J. Tanaka, Y. Togano,
T. Tomai, H. T. Törnqvist, J. Tscheuschner, T. Uesaka, V. Wagner, H. Yamada, B. Yang, L. Yang, Z. H. Yang, M. Yasuda, K. Yoneda,
L. Zanetti, J. Zenihiro and M. V. Zhukov, “Observation of a correlated free four-neutron system,” Nature 606, 678 (2022).
A. I. Stefanescu, V. Panin, L. Trache, T. Motobayashi, H. Otsu, A. Saastamoinen, T. Uesaka, L. Stuhl, J. Tanaka, D. Tudor, I. C. Stefanescu,
A. E. Spiridon, K. Yoneda, H. Baba, M. Kurokawa, Y. Togano, Z. Halasz, M. Sasano, S. Ota, Y. Kubota, D. S. Ahn, T. Kobayashi,
Z. Elekes, N. Fukuda, H. Takeda, D. Kim, E. Takada, H. Suzuki, K. Yoshida, Y. Shimizu, H. N. Liu, Y. L. Sun, T. Isobe, J. Gibelin,
P. J. Li, J. Zenihiro, F. M. Marqués, M. N. Harakeh, G. G. Kiss, A. Kurihara, M. Yasuda, T. Nakamura, S. Park, Z. Yang, T. Harada,
M. Nishimura, H. Sato, I. S. Hahn, K. Y. Chae, J. M. Elson, L. G. Sobotka, and C. A. Bertulani, “Silicon tracker array for RIB
experiments at SAMURAI,” Eur. Phys. J. A 58, 223 (2022).
M. Enciu, H. N. Liu, A. Obertelli, P. Doornenbal, F. Nowacki, K. Ogata, A. Poves, K. Yoshida, N. L. Achouri, H. Baba, F. Browne,
D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, M. L. Cortés, A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, C. Hilaire,
T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai,
M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L. X. Chung,F. Flavigny, S. Franchoo, I. Gasparic, R. -B. Gerst, J. Gibelin, K. I. Hahn, D. Kim, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, P. J. Li,
B. D. Linh, T. Lokotko, M. Maccormick, K. Moschner, T. Nakamura, S. Y. Park, D. Rossi, E. Sahin, P. -A. Söderström, D. Sohler,
S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti,“Extended p3/2 Neutron Orbital and the N = 32 Shell Closure in 52 Ca ,” Phys. Rev. Lett. 129, 262501 (2022).
T. Nishi, K. Itahashi, D. Ahn, G. P. A. Berg, M. Dozono, D. Etoh, H. Fujioka, Naoki Fukuda, N. Fukunishi, H. Geissel, E. Haettner, T. Hashimoto, R. S. Hayano, S. Hirenzaki, H. Horii, N. Ikeno, N. Inabe, M. Iwasaki, D. Kameda, K. Kisamori, Y. Kiyokawa,
T. Kubo, K. Kusaka, M. Matsushita, S. Michimasa, G Mishima, H. Miya, D. Murai, H. Nagahiro, M. Niikura, N. N. -Togawa, S. Ota,
N. Sakamoto, K. Sekiguchi, Y. Shiokawa, H. Suzuki, K. Suzuki, M. Takaki, H. Takeda, Y. K. Tanaka, T. Uesaka, Y. Wada, A. Watanabe,
Y. N. Watanabe, H. Weick, H. Yamakami, Y. Yanagisawa, K. Yoshida, and piAF Collaboration, “Chiral symmetry restoration at highmatter density observed in pionic atoms,” Nat. Phys. 19, 788–793 (2023). DOI:10.1038/s41567-023-02001-x .
Y. Kawashima, T. Hamachi, A. Yamauchi, K. Nishimura, Y. Nakashima, S. Fujiwara, N. Kimizuka, T. Ryu, T. Tamura, M. Saigo, K. Onda,
S. Sato, Y. Kobori, K. Tateishi, T. Uesaka, G. Watanabe, K. Miyata and N. Yanai, “Singlet ﬁssion as a polarized spin generator for
dynamic nuclear polarization,” Nat. Commun. 14, 1056 (2023).
K. Nishimura, R. Yabuki, T. Hamachi, N. Kimizuka, K. Tateishi, T. Uesaka, and N. Yanai, “Dynamic electron polarization lasting morethan 10 µs by hybridizing porphyrin and TEMPO with ﬂexible linkers,” J. Phys. Chem. B 127, 1219 (2023).
H. F. Li, S. Naim, T. M. Sprouse, M. R. Mumpower, Y. Abe, Y. Yamaguchi, D. Nagae, F. Suzaki, M. Wakasugi, H. Arakawa, W. B. Dou,
D. Hamakawa, S. Hosoi, Y. Inada, D. Kajiki, T. Kobayashi, M. Sakaue, Y. Yokoda, T. Yamaguchi, R. Kagesawa, D. Kamioka,
T. Moriguchi, M. Mukai, A. Ozawa, S. Ota, N. Kitamura, S. Masuoka, S. Michimasa, H. Baba, N. Fukuda, Y. Shimizu, H. Suzuki,
H. Takeda, D. S. Ahn, M. Wang, C. Y. Fu, Q. Wang, S. Suzuki, Z. Ge, Yu. A. Litvinov, G. Lorusso, P. M. Walker, Zs. Podolyak, andT. Uesaka, “First application of mass measurements with the Rare-RI Ring reveals the solar r-process abundance trend at A = 122 andA = 123,” Phys. Rev. Lett. 128, 152701 (2022).
S. Kaur, R. Kanungo, W. Horiuchi, G. Hagen, J. D. Holt, B. S. Hu, T. Miyagi, T. Suzuki, F. Ameil, J. Atkinson, Y. Ayyad, S. Bagchi,
D. Cortina-Gil, I. Dillmann, A. Estradé, A. Evdokimov, F. Farinon, H. Geissel, G. Guastalla, R. Janik, R. Knöbel, J. Kurcewicz,- 249 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Y. A. Litvinov, M. Marta, M. Mostazo, I. Mukha, C. Nociforo, H. J. Ong, T. Otsuka, S. Pietri, A. Prochazka, C. Scheidenberger,
B. Sitar, P. Strmen, M. Takechi, J. Tanaka, I. Tanihata, S. Terashima, J. Vargas, H. Weick, and J. S. Winﬁeld, “Proton distribution radiiof 16–24 O: signatures of new shell closures and neutron skin,” Phys. Rev. Lett. 129, 142502 (2022).
K. Yoshida and J. Tanaka, “α knockout reaction as a new probe for α formation in α-decay,” Phys. Rev. C 106, 014621 (2022).
H. Sagawa, S. Yoshida, T. Naito, T. Uesaka, J. Zenihiro, J. Tanaka, and T. Suzuki, “Isovector density and isospin impurity in 40 Ca,” Phys.
Lett. B 829, 137072 (2022).
M. Heil, A. Kelić-Heil, L. Bott, T. Almusidi, H. Alvarez-Pol, L. Atar, L. Atkins, T. Aumann, J. Benlliure, K. Boretzky, B. Brückner,
P. Cabanelas, C. Caesar, E. Casarejos, J. Cederkall, L. Chulkov, A. Corsi, J. Dueñas, P. Erbacher, S. E. Rodriguez, A. Falduto, M. Feijoo, A. Frotscher, J. Frühauf, I. Gašparić, M. J. G. Borge, J. Gerbig, R. Gernhäuser, M. Gilbert, J. Glorius, B. Gnoﬀo, K. Göbel,
D. G. Caamaño, A. Grein, A. -L. Hartig, H. Heggen, M. Heine, A. Heinz, M Holl, I. Homm, A. Horvat, H. T. Johansson, B. Jonson,
N. Kalantar-Nayestanaki, A. Kamenyero, A. Khodaparast, O. Kiselev, P. Klenze, M. Knösel, K. Koch, D. Körper, T Kröll, D Kurtulgil,
N Kurz, B Löher, C Langer, C Lehr, Y Litvinov, H Liu, S Murillo Morales, E Nácher, T Nilsson, J Park, S. Paschalis, L. Pellegri,
A. Perea, M. Petri, T. Pohl, L. Ponnath, R. Popočovski, R. Reifarth, H. -B. Rhee, J. L. Sanchez, D. Rossi, C. Sürder, A. M. SánchezBenı́tez, D. Savran, H. Scheit, H. Simon, Z. Slavkovská, S. Storck-Dutine, Y. Sun, H. T. Törnqvist, J. Tanaka, O. Tengblad, B. Thomas,
L. Varga, M. Volknandt, V. Wagner, F. Wamers, L. Zanetti, “A new Time-of-ﬂight detector for the R3B setup,” Eur. Phys. J. A 58, 248(2022).
T. Koiwai, K. Wimmer, P. Doornenbal, A. Obertelli, C. Barbieri, T. Duguet, J. Holt, T. Miyagi, P. Navrátil, K. Ogata, N. Shimizu,
V. Somà, Y. Utsuno, K. Yoshida, N. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, M. Cortés,
A. Delbart, J. -M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, H. Liu, T. Motobayashi,
I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. Sun, Y. Togano, T. Uesaka,
K. Yoneda, O. Aktas, T. Aumann, L. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R. -B. Gerst, J. Gibelin, K. Hahn, D. Kim, Y. Kondo,
P. Koseoglou, J. Lee, C. Lehr, B. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Park, D. Rossi, E. Sahin, P. A. Söderström, D. Sohler, S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang,
M. Yasuda, and L. Zanetti, “A ﬁrst glimpse at the shell structure beyond 54 Ca: Spectroscopy of 55 K, 55 Ca, and 57 Ca,” Phys. Lett. B 827,
136953 (2022).
B. Le Croma, M. Assi’ea, Y. Blumenfelda, J. Guillota, H. Sagawab, T. Suzukic, M. Honmab, N. L. Achourid, B. Bastine, R. Borceaf,
W. N. Catfordg, E. Cl’emente, L. C’acerese, M. Caama’noh, A. Corsii, G. De Francee, F. Delaunayd, N. De S’er’evillea, B. FernandezDominguezh, M. Fisichellaj, S. Franchooa, A. Georgiadoua, J. Gibelind, A. Gilliberti, F. Hammachea, O. Kamaloue, A. Knaptong,
V. Lapouxi, S. Leblondd, A. O. Macchiavellik, F. M. Marqu’esd, A. Mattag, L. M’enagere, P. Morfouacea, N. A. Orrd, J. Pancine,
X. Pereira-Lopezd,h, L. Perrota, J. Piote, E. Pollaccoi, D. Ramos, T. Rogere, F. Rotaruf, A. M. S’anchez-Ben’ıtezl, M. S’enovillei,
O. Sorline, M. Stanoiuf, I. Stefana, C. Stodele, D. Suzukia, J. -C. Thomase, and M. Vandebrouck, “Neutron-proton pairing in the N = Z
radioactive f p-shell nuclei 56 Ni and 52 Fe probed by pair transfer,” Phys. Lett. B 829, 137057 (2022).
Y. Tanimura, H. Sagawa, T. Sun, and E. Hiyama, “Xi hypernuclei 15 XiC, 12 XiBe and Xi-N two-body interaction,” Phys. Rev. C 105,
044324 (2022).
M. J. Yang, C. L. Bai, H. Sagawa, and H. Q. Zhang, “The Gamow-Teller transitions in magic nuclei calculated by the charge-exchange
subtracted second random phase approximation,” Phys. Rev. C 106, 014319 (2022).
J. -Y. Xu, Z. -Z. Li, B. -H. Sun, Y. -F. Niu, X. Roca-Maza, H. Sagawa, and I. Tanihata, “Constraining equation of state of nuclear matterby charge-changing cross section measurements of mirror nuclei,” Phys. Lett. B 833, 137333 (2022).
K. Hagino and H. Sagawa, “Spatial correlation of a particle-hole pair with a repulsive isovector interaction,” Phys. Phys. C 106, 034313(2022).
T. Naito, X. Roca-Maza, G. Colo, H. Liang, and H. Sagawa, “Isospin symmetry breaking in the charge radius diﬀerence of mirror nuclei,”
Phys. Rev. C 106, L061306 (2022).
M. J. Yang, H. Sagawa, C. L. Bai, and H. Q. Zhang, “Eﬀects of two particle-two hole conﬁgurations and tensor force on beta decay ofmagic nuclei,” Phys. Rev. C 107, 014325 (2023).
N. Matsumoto, K. Nishimura, N. Kimizuka, Y. Nishiyama, K. Tateishi, T. Uesaka, and N. Yanai, “Proton hyperpolarization relay fromnanocrystals to liquid water,” J. Am. Chem. Soc. 144, 18023 (2022).
T. Furuno, T. Doi, K. Himi, T. Kawabata, S. Adachi, H. Akimune, S. Enyo, Y. Fujikawa, Y. Hijikata, K. Inaba, M. Itoh, S. Kubono,
Y. Matsuda, I. Murat, M. Murata, S. Okamoto, K. Sakanash, and S. Tamaki, “Measurement of 12 C(n, n′ ) reaction cross section todetermine triple-alpha reaction rate in high-density environments,” EPJ Web Conf. 260, 11010 (2022).
M. Abdullah, S. Bagchi, M. N. Harakeh, and the E497 collaboration, “Eﬀect of ground-state shape deformation on the isoscalar giant
monopole resonance in Nd isotopes,” Proc. DAE Symp. Nucl. Phys. 66, 94 (2022).

Presentations[International Conferences/Workshops]
H. Sagawa (invited), “What can we learn from the nuclear ground state densities?,” 6th Topical Workshop on Modern Aspects in Nuclear
Stracutre, Bormio, Italy, February 6–11, 2022.
H. Sagawa (invited), “Beyond mean ﬁeld model for nuclear collective states,” The 16th International Symposium on Origin of Matter and
Evolution of Galaxies (OMEG2022), Hanoi, Vietnam, October 25–28, 2022.
H. Sagawa (invited), “What can we learn from the nuclear ground state densities?,” Physics of RI: Recent progress andperspectives,
RIKEN, Saitama, Japan, May 30–June 1, 2022.
H. Sagawa (oral), “Some topics of isoscalar spin-triplet pairing,” YIPQS long-term workshop, “Mean-ﬁeld and cluster dynamics in nuclear
systems 2022 (MCD2022), Kyoto University, Kyoto, May 9–June 17, 2023.

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H. Sagawa (invited), “What can we learn from the nuclear ground state densities?,” Focus Program: A quest for exotica in rare-earth
elements, Pohang, Korea, August 22–26, 2022.
J. Tanaka (invited), “Clustering phenomena in dilute neutron-rich matter,” The 15th Asia Paciﬁc Physics Conference (APPC15) August
21–26, 2022.
Y. Kubota (invited), “Surface localization of the dineutron in nuclei,” in Halo Week 2022, Bergen, Norway, 2022.
Y. Kubota (oral), “Recent updates on SAMURAI18 experiment,” in SAMURAI International Collaboration Workshop 2022, Ookayama,
Japan, 2022.
Y. Kubota (oral), “SAMURAI: Recent advances in analysis and prospects for future experiments,” in RIBF Users Meeting 2022.
Y. Hijikata (oral), “Developmetn of gaseous Xe scintillator for particle identiﬁcation of high-intensity RI beams,” The 2022 Annual
Meeting of the JSPS/NSFC/NRF A3 Foresight Program, Osaka, Japan, February 14, 2023.
T. Tsuji (oral), “Development of TOGAXSI array,” SAMURAI International Collaboration Workshop 2022, Meguro-ku, Tokyo (Tokyo
titech University), September 2–3, 2022.
T. Tsuji (oral), “Development of large GAGG:Ce calorimeter for measurements of the cluster knockout reactions,” A3 Foresight Annual
Meeting 2022, Osaka, Japan (OsakaInternational Convention Center), February 13–15, 2023.
T. Uesaka (invited), “Clustering in heavy nuclei probed with knockout reactions,” 6th Topical Workshop on Modern Aspects in Nuclear
Stracutre, Bormio, Italy, February 6–11, 2022.
T. Uesaka (invited), “Recent progress in nuclear cluster physics,” 28th International Nuclear Physics Conference (INPC 2022), Cape town,
South Africa, September 11–16, 2022.
T. Uesaka (invited), “ONOKORO project—knockout reaction studies of clusters in heavy nuclei—,” Direct Reactions with Exotic Beams(DREB2022), Santiago de Compostela, Spain, June 26–July 1, 2022.
J. Tanaka (poster), “Detector array TOGAXSI for inverse-kinematics cluster and nucleon knockout reaction experiment,” EMIS 2022,
Daejeon, Korea, October 3–7, 2022.
Y. Hijikata (poster), “Development of gaseous Xe scintillator for particle identiﬁcation of high-intensity and heavy-ion beams,” EMIS
2022, Daejeon, Korea, October 3–7, 2022.
R. Tsuji (poster) , “Development of large GAGG:Ce calorimeter for measurements of the cluster knockout reactions,” EMIS2022, Dejean,
Korea, October 3–7, 2022.
K. Higuchi (poster), “Development of silicon-strip for cluster knockout reactions,” EMIS2022, Daejon, Korea, October 3–7, 2022.

[Domestic Conferences/Workshops]

田中純貴（招待講演）, 「原子核基底状態のアルファクラスターと ONOKORO プロジェクト」, 日本物理学会 2023 年春季大会, シンポジウム講演, 2023 年 3 月 22–25 日.
久保田悠樹（招待講演）, 「ノックアウト反応で調べるボロミアン核のダイニュートロン相関」, RCNP 研究会「微視的系と巨視的系における核子対凝縮相」, 茨木市 (大阪大学核物理研究センター), 2022 年 9 月 26–28 日.
立石健一郎（口頭論文）, 「トリプレット DNP による室温核偏極: 原理・装置・現状の課題」, DNP 研究会, 豊中市 (大阪大学南部
陽一郎ホール), 2022 年 7 月 12 日.
立石健一郎（口頭論文）, 「核スピン偏極技術とその応用」, 第４回若手放談会: エキゾチック核物理の将来, 神戸市 (理研神戸), 2023
年 3 月 15–17 日.
立石健一郎（口頭論文）, 「Development of High-temperature Nuclear Polarization Method for Hypersensitive NMR Spectroscopy」,
Frontier of Dynamic Structural Biology, 吹田市 (大阪大学), 2022 年 10 月 17–18 日.
土方佑斗（口頭論文）, 「錫 112 の弾性散乱と錫同位体でのアイソスカラー・アイソベクトル密度分布変化」, おのころ戸隠夏合宿,
長野市 (JA 長野県ビル), 2022 年 7 月 29–31 日.
樋口浩志（口頭論文）, 「クラスターノックアウト反応に向けた荷電粒子用シリコン・ストリップ検出器の開発」, 日本物理学会 2022
年春季大会, 2022 年 3 月 15–18 日.
樋口浩志（口頭論文）, 「Strip-Si detector performance report from HIMAC exp」, おのころプロジェクトローカルコラボレーション
ミーティング, 京都市, 2022 年 5 月 19–20 日.
樋口浩志（口頭論文）, 「TOGAXSI で調べる核内クラスターのシェル構造」, おのころプロジェクト戸隠夏合宿, 長野市 (JA 長野県ビル), 2022 年７月 29–30 日.
辻崚太郎（口頭論文）, 「GAGG(Ce) performance; report from HIMAC exp」, おのころプロジェクトローカルコラボレーションミー
ティング, 京都市, 2022 年 5 月 19–20 日.
辻崚太郎（口頭論文）, 「40–52 Ca(p, pX) とクラスター種の同位体依存性」, おのころプロジェクト戸隠夏合宿, 長野市 (JA 長野県ビル), 2022 年 07 月 29–30 日.
土方佑斗（ポスター）, 「原子核実験の先端データ収集システム—標準化と将来—」, 茨木市 (大阪大学 RCNP), 2023 年 3 月 16 日.

Awards

久保田悠樹, 第 29 回 原子核談話会新人賞.
久保田悠樹, 第 17 回 日本物理学会若手奨励賞.

Other

土方佑斗（パネルディスカッション）, 「原子核実験の先端データ収集システム—標準化と将来—」, 茨木市（大阪大学 RCNP）, 2023
年 3 月 16 日.

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RIKEN Accel. Prog. Rep. 56 (2023)

Nuclear Science and Transmutation Research Division
Nuclear Spectroscopy Laborarory
1. Abstract

The research group has conducted nuclear-physics studies utilizing stopped/slowed-down radioactive-isotope (RI) beams mainly
at the RIBF facility. These studies are based on the technique of nuclear spectroscopy such as β-ray-detected NMR (β-NMR), γPAD (Perturbed Angular Distribution), laser, and Mössbauer among other methods that takes advantage of intrinsic nuclear properties
such as nuclear spins, electromagnetic moments, and decay modes. In particular, techniques and devices for the production of spincontrolled RI beams have been developed and combined to the spectroscopic studies, which enable high-sensitivity measurements ofspin precessions/resonances through a change in the angular distribution of radiations. Anomalous nuclear structures and propertiesof far unstable nuclei are investigated from thus determined spin-related observables. The group also aims to apply such techniques tointerdisciplinary ﬁelds such as fundamental physics and materials science by exploiting nuclear probes.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Nuclear spectroscopy utilizing spin-oriented fast RI beams
Nuclear/Atomic laser spectroscopy & SLOWRI R&DApplication of RI probes to materials science
Fundamental physics: Study of symmetry

3. Summary of Research Activity(1) Nuclear spectroscopy utilizing spin-oriented fast RI beams
Measurements of static electromagnetic nuclear moments over a substantial region of the nuclear chart have been conducted forstructure studies on the nuclei far from the β-decay stability. Utilizing nuclear spin orientation phenomena of RIs created in the
projectile-fragmentation reaction, ground- and excited-state electromagnetic nuclear moments been determined by means of the βray-detected nuclear magnetic resonance (β-NMR) and the γ-ray time diﬀerential perturbed angular distribution (γ-TDPAD) methods.
In particular, a new method developed for controlling spin in a system of rare RIs, taking advantage of the mechanism of the two-step
projectile fragmentation reaction combined with the momentum-dispersion matching technique, has been developed and employedmaking fully use of world’s highest intensity rare RIBs delivered from BigRIPS for rare isotopes.
(2) Nuclear/Atomic laser spectroscopy & SLOWRI R&D
The group has been conducting system development for nuclear laser spectroscopy from the following two approaches in orderto realize experiments for rare isotopes at RIBF. One is collinear laser spectroscopy for a large variety of elements using sloweddown RI beams produced via a projectile-fragmentation reaction, which can be achieved only by the universal low-energy RI-beamdelivery system, SLOWRI, under installation in collaboration with the SLOWRI Team. This slowed-down RI-beam scheme enables
to perform high-precision laser spectroscopy even with fast-fragmentation-based RIBs without the elemental limitation problematicin the ISOL-based RIBs.
The other approach is a new method utilizing superﬂuid helium (He II) as a stopping medium of energetic RI beams, in which thecharacteristic atomic properties of ions surrounded by superﬂuid helium enables us to perform unique nuclear laser spectroscopy. RIions trapped in He II are known to exhibit a characteristic excitation spectrum signiﬁcantly blue-shifted compared with the emission
one. Consequently, the background derived from the excitation-laser stray light, which often causes serious problems in measurements,
can be drastically reduced.
(3) Application of RI probes to materials science
The application of RI and heavy ion beams as a probe for condensed matter studies is also conducted by the group. The microscopic material dynamics and properties have been investigated through the deduced internal local ﬁelds and the spin relaxation of
RI probes based on various spectroscopies utilizing RI probes such as β-NMR/NQR spectroscopy, Mössbauer spectroscopy, the γ-ray
time diﬀerential perturbed angular correlation (γ-TDPAC) spectroscopy. Furthermore, studies on the control of electrical conductivityof diamond by boron and nitrogen implantation are ongoing.
Provided that highly spin-polarized RI probes are produced independently of their element properties and doped into a substanceas an impurity, the constituent particle of the substance can be substituted by the same element RI probe without changing the material
structure. This scheme provides a new opportunity for materials-science researches, but a key technology, production of elementindependent highly spin-polarized RI beams, has not yet been achieved. In this subject, the group has conducted R&D studies torealize an ultra-slow & highly-spin-polarized RI beams, based on the technique of the atomic beam resonance.
(4) Fundamental physics: Study of symmetry
The nuclear spins of stable and unstable isotopes sometimes play important roles in fundamental physics research. New experimental methods and devices have been developed for studies of the violation of time reversal symmetry (T-violation) using spinpolarized nuclei. These experiments aim to detect the small frequency shift in the spin precession arising from new mechanisms
beyond the Standard Model.

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RIKEN Accel. Prog. Rep. 56 (2023)

Members
Director
Hideki UENO
Research/Technical Scientists
Hiroki YAMAZAKI (Senior Research Scientist)
Isao WATANABE (Senior Research Scientist)

Aiko TAKAMINE (Research Scientist)
Shintaro GO (Research Scientist)

Research & Development Scientist
Tetsu SONODA
Contract Researcher
Takashi ABE
Special Postdoctoral Researcher
Momo MUKAI
Postdoctoral Researchers
Minori TAJIMA

Kei IMAMURA (CPR)

Research Associate
Aleksey A. GLADKOVInternational Program Associate
Muhammad A. SYAKUUR (Univ. Padjadjaran)
Senior Visiting Scientists
Yukari MATSUO (Hosei Univ.)

Takaharu OTSUKA (Univ. of Tokyo)

Visiting Scientists
Dimiter Loukanov BALABANSKI (IFIN-HH)
Jean-Michel DAUGAS (CNRS)
Georgi GEORGIEV (CNRS-IN2P3)
Yuichi ICHIKAWA (Kyushu Univ.)
Anders KASTBERG (Univ. of Tokyo)
Yoshio KOBAYASHI (Univ. of Electro-Commun.)
Kenya M. KUBO (Int’l Christian Univ.)
Jun MIYAZAKI (Tokyo Denki Univ.)
Takamasa MOMOSE (The Univ. of British Columbia)
Jin NAKAMURA (Univ. of Electro-Commun.)

Hiroki NISHIBATA (Kyushu Univ.)
Tomoya SATO (Tokyo Tech)
Wataru SATO (Kanazawa Univ.)
Tadayuki TAKAHASHI (Univ. of Tokyo)
Shinichiro TAKEDA (Univ. of Tokyo)
Satoshi TSUTSUI (Japan Synchrotron Radiation Res. Inst.)
Shin WATANABE (JAXA)
Deyan T. YORDANOV (CNRS)
Akihiro YOSHIMI (Okayama Univ.)

Student Trainees
Sai AKIMOTO (Hosei Univ.)
Manami ITO (Hosei Univ.)
Satoshi TANAKA (Hosei Univ.)
Hiroki ENDO (Hosei Univ.)
Yusuke FUKUZAWA (Hosei Univ.)
Kai KIKUCHI (Hosei Univ.)
Rikuta MITSUYASU (Hosei Univ.)
Takaya MIWA (Hosei Univ.)

Shoki TAKAHASHI (Hosei Univ.)
Shinya SASAMORI (Hosei Univ.)
Yutaka TSUZUKI (Univ. of Tokyo)
Mio YOSHIDA (Univ. of Electro-Commun.)
Yoko KIMURA (Osaka Univ.)
Takato SUGISAKI (Osaka Univ.)
Roman L. WIXINGER (Univ. of Tokyo)
Konstantin STOYCHEV (Univ. of Paris-Saclay)

AssistantIzumi YOSHIDA- 253 -

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RIKEN Accel. Prog. Rep. 56 (2023)

List of Publications & Presentations
Publications[Original Papers]
M. Mukai, Y. Hirayama, Y. X. Watanabe, H. Watanabe, H. Koura, S. C. Jeong, H. Miyatake, M. Brunet, S. Ishizawa, F. G. Kondev,
G. J. Lane, Yu. A. Litvinov, T. Niwase, M. Oyaizu, Zs. Podolyák, M. Rosenbusch, P. Schury, M. Wada, and P. M. Walker, “Groundstate β-decay spectroscopy of 187 Ta,” Phys. Rev. C 105, 034331-1–6 (2022). DOI: 10.1103/PhysRevC.105.034331 .
Y. Ishibashi, A. Gladkov, Y. Ichikawa, A. Takamine, H. Nishibata, T. Sato, H. Yamazaki, T. Abe, J. M. Daugas, T. Egami, T. Fujita,
G. Georgiev, K. Imamura, T. Kawaguchi, W. Kobayashi, Y. Nakamura, A. Ozawa, M. Sanjo, N. Shimizu, D. Tominaga, L. C. Tao,
K. Asahi, and H. Ueno, “Nuclear magnetic moment of the neutron-rich nucleus 21 O,” Phys. Rev. C 107, 024306-1–7 (2023).
DOI: 10.1103/PhysRevC.107.024306 .
S. Iimura, M. Rosenbusch, A. Takamine, Y. Tsunoda, M. Wada, S. Chen, D. Hou, W. Xian, H. Ishiyama, S. Yan, P. Schury, H. Crawford,
P. Doornenbal, Y. Hirayama, Y. Ito, S. Kimura, T. Koiwai, T. Kojima, H. Koura, J. Lee, J. Liu, S. Michimasa, H. Miyatake, J. Moon,
S. Naimi, S. Nishimura, T. Niwase, A. Odahara, T. Otsuka, S. Paschalis, M. Petri, N. Shimizu, T. Sonoda, D. Suzuki, Y. Watanabe,
K. Wimmer, and H. Wollnik, “Study of the N = 32 and N = 34 shell gap for Ti and V by the ﬁrst high-precision multireﬂection time-ofﬂight mass measurements at BigRIPS-SLOWRI,” Phys. Rev. Lett. 130, 012501-1–6 (2023). DOI: 10.1103/PhysRevLett.130.012501 .
T. Otsuka, T. Abe, T. Yoshida, Y. Tsunoda, N. Shimizu, N. Itagaki, Y. Utsuno, J. Vary, P. Maris, and H. Ueno, “α-clustering inatomic nuclei from ﬁrst principles with statistical learning and the Hoyle state character,” Nat. Commum. 13, 2234-1–10 (2022).
DOI: 10.1038/s41467-022-29582-0 .
K. Nakamura, S. Nagase, T. Nakashita, T. Hayamizu, T. Aoki, H. Nagahama, N. Ozawa, M. Sato, K. Yamane, M. Fukase, D. Uehara,
A. Takamine, and Y. Sakemi, “Development of a laser frequency stabilization and an optical transmission system for the francium
electric dipole moment search,” J. Phys. Conf. Ser. 2249, 012010-1–7 (2022). DOI: 10.1088/1742-6596/2249/1/012010 .
T. Hashimoto, S. Aikawa, T. Akaishi, H. Asano, M. Bazzi, D. A. Bennett, M. Berger, D. Bosnar, A. D. Butt, C. Curceanu, W. B. Doriese,
M. S. Durkin, Y. Ezoe, J. W. Fowler, H. Fujioka, J. D. Gard, C. Guaraldo, F. P. Gustafsson, C. Han, R. Hayakawa, R. S. Hayano,
T. Hayashi, J. P. Hays-Wehle, G. C. Hilton, T. Hiraiwa, M. Hiromoto, Y. Ichinohe1, M. Iio, Y. Iizawa, M. Iliescu, S. Ishimoto,
Y. Ishisaki, K. Itahashi, M. Iwasaki, Y. Ma, T. Murakami, R. Nagatomi, T. Nishi, H. Noda, H. Noumi, K. Nunomura, G. C. O’Neil,
T. Ohashi, H. Ohnishi, S. Okada, H. Outa, K. Piscicchia, C. D. Reintsema, Y. Sada, F. Sakuma, M. Sato, D. R. Schmidt, A. Scordo,
M. Sekimoto, H. Shi, K. Shirotori, D. Sirghi, F. Sirghi, K. Suzuki, D. S. Swetz, A. Takamine, K. Tanida, H. Tatsuno, C. Tripp,
J. Uhlig, J. N. Ullom, S. Yamada, T. Yamaga, T. Yamazaki, and J. Zmeskal (J-PARC E62 Collaboration), “Measurements of stronginteraction eﬀects in kaonic-helium isotopes at sub-eV precision with X-ray microcalorimeters,” Phys. Rev. Lett. 128, 112503-1–6(2022). DOI: 10.1103/PhysRevLett.128.112503 .
M. Rosenbusch, M. Wada, S. Chen, A. Takamine, S. Iimura, D. Hou, W. Xian, S. Yan, P. Schury, Y. Hirayama, Y. Ito, H. Ishiyama,
S. Kimura, T. Kojima, J. Lee, J. Liu, S. Michimasa, H. Miyatake, M. Mukai, J. Y. Moon, S. Nishimura, S. Naimi, T. Niwase, T. Sonoda,
Y. X. Watanabe, and H. Wollnik, “The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN’s RIBF
facility,” Nucl. Instrum. Methods Phys. Res. A 1047, 167824-1–12 (2022). DOI: 10.1016/j.nima.2022.167824 .
D. S. Ahn, J. Amano, H. Baba, N. Fukuda, H. Geissel, N. Inabe, S. Ishikawa, N. Iwasa, T. Komatsubara, T. Kubo, K. Kusaka,
D. J. Morrissey, T. Nakamura, M. Ohtake, H. Otsu, T. Sakakibara, H. Sato, B. M. Sherrill, Y. Shimizu, T. Sumikama, H. Suzuki,
H. Takeda, O. B. Tarasov, H. Ueno, Y. Yanagisawa, and K. Yoshida, “Discovery of 39 Na,” Phys. Rev. Lett. 129, 212502-1–7 (2022).
DOI: 10.1103/PhysRevLett.129.212502 .
G. G. Kiss, A. Vitéz-Sveiczer, Y. Saito, A. Tarifeño-Saldivia, M. Pallas, J. L. Tain, I. Dillmann, J. Agramunt, A. Algora, C. DomingoPardo, A. Estrade, C. Appleton, J. M. Allmond, P. Aguilera, H. Baba, N. T. Brewer, C. Bruno, R. Caballero-Folch, F. Calvino,
P. J. Coleman-Smith, G. Cortes, T. Davinson, N. Fukuda, Z. Ge, S. Go, C. J. Griﬃn, R. K. Grzywacz, O. Hall, A. Horváth, J. Ha,
L. J. Harkness-Brennan, T. Isobe, D. Kahl, T. T. King, A. Korgul, S. Kovács, R. Krücken, S. Kubono, M. Labiche, J. Liu, J. Liang,
M. Madurga, K. Miernik, F. Molina, A. I. Morales, M. R. Mumpower, E. Nacher, A. Navarro, N. Nepal, S. Nishimura, M. PiersaSiłkowska, V. Phong, B. C. Rasco, B. Rubio, K. P. Rykaczewski, J. Romero-Barrientos, H. Sakurai, L. Sexton, Y. Shimizu, M. Singh,
T. Sprouse, T. Sumikama, R. Surman, H. Suzuki, T. N. Szegedi, H. Takeda, A. Tolosa, K. Wang, M. Wolinska-Cichocka, P. Woods,
R. Yokoyama, and Z. Xu, “Measuring the β-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the
nucleosynthesis yields in the rare-earth region,” Astrophys. J. 936, 107-1–18 (2022). DOI: 10.3847/1538-4357/ac80fc .
V. H. Phong, S. Nishimura, G. Lorusso, T. Davinson, A. Estrade, O. Hall, T. Kawano, J. Liu, F. Montes, N. Nishimura, R. Grzywacz,
K. P. Rykaczewski, J. Agramunt, D. S. Ahn, A. Algora, J. M. Allmond, H. Baba, S. Bae, N. T. Brewer, C. G. Bruno, R. Caballero-Folch,
F. Calviño, P. J. Coleman-Smith, G. Cortes, I. Dillmann, C. Domingo-Pardo, A. Fijalkowska, N. Fukuda, S. Go, C. J. Griﬃn, J. Ha,
L. J. Harkness-Brennan, T. Isobe, D. Kahl, L. H. Khiem, G. G. Kiss, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, J. Liang, Z. Liu,
K. Matsui, K. Miernik, B. Moon, A. I. Morales, P. Morrall, N. Nepal, R. D. Page, M. Piersa-Siłkowska, V. F. E. Pucknell, B. C. Rasco,
B. Rubio, H. Sakurai, Y. Shimizu, D. W. Stracener, T. Sumikama, H. Suzuki, J. L. Tain, H. Takeda, A. Tarifeño-Saldivia, A. TolosaDelgado, M. Wolińska-Cichocka, P. J. Woods, and R. Yokoyama, “β-delayed one and two neutron emission probabilities southeast of132
Sn and the odd-even systematics in r-process nuclide abundances,” Phys. Rev. Lett. 129, 172701-1–7 (2022). DOI: 10.1103/PhysRevLett.129.172701 .
M. Tanaka, P. Brionnet, M. Du, J. Ezold, K. Felker, B. J. P. Gall, S. Go, R. Grzywacz, H. Haba, K. Hagino, S. Hogle, S. Ishizawa, D. Kaji,
S. Kimura, T. T. King, Y. Komori, R. K. Lemon, M. G. Leonard, K. Morimoto, K. Morita, D. Nagae, N. Naito, T. Niwase, B. C. Rasco,J. B. Roberto, K. P. Rykaczewski, S. Sakaguchi, H. Sakai, Y. Shigekawa, D. W. Stracener, S. VanCleve, Y. Wang, K. Washiyama,
and T. Yokokita, “Probing optimal reaction energy for synthesis of element 119 from 51 V + 248 Cm reaction with quasielastic barrier
distribution measurement,” J. Phys. Soc. Jpn. 91, 084201-1–17 (2022). DOI: 10.7566/JPSJ.91.084201 .
Y. Hirayama, M. Mukai, Y. X. Watanabe, P. Schury, H. Nakada, J. Y. Moon, T. Hashimoto, S. Iimura, S. C. Jeong, M. Rosenbusch,- 254 -

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M. Oyaizu, T. Niwase, M. Tajima, A. Taniguchi, M. Wada, and H. Miyatake, “In-gas-cell laser resonance ionization spectroscopy of200, 201
Pt,” Phys. Rev. C 106, 034326-1–11 (2022). DOI: 10.1103/PhysRevC.106.034326 .
C. Amsler, H. Breuker, S. Chesnevskaya, G. Costantini, R. Ferragut, M. Giammarchi, A. Gligorova, G. Gosta, H. Higaki, E. D. Hunter,
C. Killian, V. Kletzl, V. Kraxberger, N. Kuroda, A. Lanz, M. Leali, V. Mäckel, G. Maero, C. Malbrunot, V. MascagnaY. Matsuda,
S. Migliorati, D. J. Murtagh, Y. Nagata, A. Nanda, L. Nowak, E. Pasino, M. Romé, M. C. Simon, M. Tajima, V. Toso, S. Ulmer,
L. Venturelli, A. Weiser, E. Widmann, T. Wolz, Y. Yamazaki, and J. Zmeskal, “Reducing the background temperature for cyclotron
cooling in a cryogenic Penning-Malmberg trap,” Phys. Plasmas 29, 083303-1–12 (2022). DOI: 10.1063/5.0093360 .
H. F. Li, S. Naimi, T. M. Sprouse, M. R. Mumpower, Y. Abe, Y. Yamaguchi, D. Nagae, F. Suzaki, M. Wakasugi, H. Arakawa, W. B. Dou,
D. Hamakawa, S. Hosoi, Y. Inada, D. Kajiki, T. Kobayashi, M. Sakaue, Y. Yokoda, T. Yamaguchi, R. Kagesawa, D. Kamioka,
T. Moriguchi, M. Mukai, A. Ozawa, S. Ota, N. Kitamura, S. Masuoka, S. Michimasa, H. Baba, N. Fukuda, Y. Shimizu, H. Suzuki,
H. Takeda, D. S. Ahn, M. Wang, C. Y. Fu, Q. Wang, S. Suzuki, Z. Ge, Yu. A. Litvinov, G. Lorusso, P. M. Walker, Zs. Podolyak, andT. Uesaka, “First application of mass measurements with the Rare-RI Ring reveals the solar r-process abundance trend at A = 122 andA = 123,” Phys. Rev. Lett. 128, 152701-1–6 (2022). DOI: 10.1103/PhysRevLett.128.152701 .
B. Moon, A. Gargano, H. Naidja, C. -B. Moon, A. Odahara, R. Lozeva, S. Nishimura, C. Yuan, F. Browne, P. Doornenbal, G. Lorusso,
Z. Patel, S. Rice, M. Si, L. Sinclair, P. -A. Soderstrom, T. Sumikama, H. Watanabe, J. Wu, Z. Y. Xu, A. Yagi, D. S. Ahn, H. Baba,
F. L. Bello Garrote, R. Daido, J. M. Daugas, F. Didierjean, Y. Fang, N. Fukuda, B. Hong, E. Ideguchi, N. Inabe, T. Ishigaki, T. Isobe,
H. S. Jung, D. Kameda, I. Kojouharov, T. Komatsubara, T. Kubo, Y. K. Kwon, C. S. Lee, P. Lee, S. Morimoto, D. Murai, M. Niikura,
H. Nishibata, I. Nishizuka, H. Sakurai, Y. Shimizu, H. Suzuki, H. Takeda, K. Tshoo, and R. Yokoyama, “First observation of theπ0h11/2 ⊗ ν0h9/2 partner orbital conﬁguration in the odd-odd 138 I nucleus,” Phys. Rev. C 105, 034334-1–7 (2022). DOI: 10.1103/PhysRevC.105.034334 .
A. Yagi, A. Odahara, H. Nishibata, R. Lozeva, C. B. Moon, S. Nishimura, K. Yoshida, N. Yoshinaga, C. Watanabe, K. Higashiyama,
T. Shimoda, R. Daido, Y. Fang, P. S. Lee, B. Moon, P. Doornenbal, G. Lorusso, P. A. Söderström, T. Sumikama, H. Watanabe,
T. Isobe, H. Baba, H. Sakurai, F. Browne, Z. Patel, S. Rice, L. Sinclair, J. Wu, Z. Y. Xu, R. Yokoyama, T. Kubo, N. Inabe, H. Suzuki,
N. Fukuda, D. Kameda, H. Takeda, D. S. Ahn, Y. Shimizu, D. Murai, F. L. Bello Garrote, J. M. Daugas, F. Didierjean, E. Ideguchi,
S. Iimura, T. Ishigaki, H. S. Jung, T. Komatsubara, Y. K. Kwon, C. S. Lee, S. Morimoto, M. Niikura, I. Nishizuka, and K. Tshoo,“Various nuclear structures in 140 Xe studied by β decay of ground and isomeric states in 140 I,” Phys. Rev. C 105, 044325-1–14 (2022).
DOI: 10.1103/PhysRevC.105.044325 .
D. Little, A. D. Ayangeakaa, R. V. F. Janssens, S. Zhu, Y. Tsunoda, T. Otsuka, B. A. Brown, M. P. Carpenter, A. Gade, D. Rhodes,
C. R. Hoﬀman, F. G. Kondev, T. Lauritsen, D. Seweryniak, J. Wu, J. Henderson, C. Y. Wu, P. Chowdhury, P. C. Bender, A. M. Forney,
and W. B. Walters, “Multistep Coulomb excitation of 64 Ni: Shape coexistence and nature of low-spin excitations,” Phys. Rev. C 106,
044313-1–13 (2022). DOI: 10.1103/PhysRevC.106.044313 .
T. Niwase, W. Xian, M. Wada, M. Rosenbusch, S. Chen, A. Takamine, J. Liu, S. Iimura, D. Hou, S. Yan, H. Ishiyama, H. Miyatake,S. Nishimura, D. Kaji, K. Morimoto, Y. Hirayama, Y. X. Watanabe, S. Kimura, P. Schury, and H. Wollnik, “Development of a β-TOF
detector: An enhancement of the α-TOF detector for use with β-decaying nuclides,” Prog. Theor. Exp. Phys. 2023, 50934006-1–9(2023). DOI: 10.1093/ptep/ptad039 .

[Book]
Y. Tsunoda and T. Otsuka, “Conﬁguration interaction approach to atomic nuclei: The shell model,” in Handbook of Nuclear Physics,
edited by I. Tanihata, H. Toki, and T. Kajino (Springer, Singapore, 2022). DOI: 10.1007/978-981-15-8818-1 17-1 .

Presentations[International Conferences/Workshops]
T. Abe (oral), “Alpha-cluster structure from ﬁrst principles,” YIPQS long-term workshop “Mean-ﬁeld and Cluster Dynamics in Nuclear
Systems 2022” (MCD2022), Kyoto, Japan & Online (Hybrid), May 9–June 17, 2022.
T. Abe (oral), “Alpha-cluster structure from ﬁrst principles,” RIKEN-YITP Workshop “Physics of RI: Recent Progress and Perspectives,”
Wako (RIKEN), Japan & Online (Hybrid), May 30–June 1, 2022.
K. Nakamura (oral), S. Nagase, T. Nakashita, T. Hayamizu, T. Aoki, H. Nagahama, N. Ozawa, K. Yamane, M. Fukase, D. Uehara,
A. Takamine, and Y. Sakemi, “400-m-Long polarization-maintaining ﬁbers for magneto-optical trapping of francium atoms,” The 15th
Paciﬁc Rim Conference on Lasers and Electro-Optics (CLEO Paciﬁc Rim, CLEO-PR 2022); International Symposium on Imaging,Sensing, and Optical Memory 2022 (ISOM’22); and the 13th International Conference on Optics-photonics Design and Fabrication(ODF’22), Sapporo, Japan, July 31–August 5, 2022.
K. Kikuchi (poster) et al., “Optimization of the stopping position of a highly energetic 84 Rb atoms injected into superﬂuid helium,” 29th
International Conference on Low Temperature Physics (LT29), Sapporo, Japan & Online (Hybrid), August 18–24, 2022.
H. Endo (poster) et al., “LIF spectrum analysis for measurement of Rb atomic bubble relaxation time in superﬂuid helium,” 29th International Conference on Low Temperature Physics (LT29), Sapporo, Japan & Online (Hybrid), August 18–24, 2022.
M. A. Syakuur (oral), A. R. Noviyanti, U. Widyaiswari, T Saragi, Risdiana, and I. Watanabe, “Comparison of eﬀective magnetic momenton impurity substitution dependence of Eu2−x Ce x Cu1−y (Zn, Ni)y O4+a−d ,” 29th International Conference on Low Temperature Physics(LT29), Sapporo, Japan & Online (Hybrid), August 18–24, 2022.
K. Imamura (poster) et al., “Laser spectroscopic method for the investigation of nuclear structure utilizing superﬂuid helium as a hostmatrix of radioisotope atoms,” 29th International Conference on Low Temperature Physics (LT29), Sapporo, Japan & Online (Hybrid),
August 18–24, 2022.
S. Go (invited), “Overview of RIBF” and “Spectroscopy of exotic nuclei,” The 21st CNS International Summer School (A3F-CNSSS22),
Kumagaya, Saitama, August 20–24, 2022.

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R. Mitsuyasu (poster) et al., “Spectral optimization of laser for excitation of Rb atoms in superﬂuid helium in accelerator experiments,”
The 25th Congress of the International Commission for Optics (ICO), Dresden, Germany & Online (Hybrid), September 5–9, 2022.
S. Akimoto (poster) et al., “Development of an eﬃcient ﬂuorescence detection system for radioisotope atoms generated at accelerators,”
The 25th Congress of the International Commission for Optics (ICO), Dresden, Germany & Online (Hybrid), September 5–9, 2022.
A. Takamine (invited), M. Rosenbusch, M. Wada, S. Iimura, D. Hou, W. Xian, S. Chen, S. Yan, H. Ishiyama, T. Niwase, S. Kimura,
Y. Hirayama, Y. Ito, T. Kojima, J. Lee, S. Michimasa, H. Miyatake, J. Y. Moon, M. Mukai, S. Naimi, T. Sonoda, P. Vi, J. M. Yap,
T. T. Yeung, and H. Wollnik, “Nuclear mass measurements with the new MRTOF-MS system at the ZeroDegree spectrometer of
BigRIPS,” 28th International Nuclear Physics Conference (INPC 2022), Cape Town, South Africa, September 11–16, 2022.
S. Go (oral), “High-spin states in 35 S: the promotion of isoscalar pair at high spin,” 28th International Nuclear Physics Conference(INPC 2022), Cape Town, South Africa, September 11–16, 2022.
A. Takamine (oral), “Development of the new helium gas catcher and nuclear mass measurements with the new MRTOF-MS behind the
ZeroDegree spectrometer at RIKEN BigRIPS,” The 19th International Conference on Electromagnetic Isotope Separators and Related
Topics (EMIS 2022), Daejeon, Korea, October 3–7, 2022.
M. Tajima (poster), A. Takamine, H. Iimura, M. Wada, S. Kimura, T. Niwase, P. Schury, A. Schuessler, J. Lassen, and H. Ueno, “Oﬄine
development for collinear laser spectroscopy at the SLOWRI facility,” The 19th International Conference on Electromagnetic Isotope
Separators and Related Topics (EMIS 2022), Daejeon, Korea, October 3–7, 2022.
A. Gladkov (poster), Y. Ishibashi, H. Yamazaki, Y. Ichikawa, A. Takamine, H. Nishibata, K. Asahi, T. Sato, T. Abe, M. Tajima, S. Go,
A. Ozawa, N. Shimizu, T. Fujita, L. C. Tao, T. Egami, D. Tominaga, T. Kawaguchi, M. Sanjo, W. Kobayashi, K. Imamura, Y. Nakamura,
G. Georgiev, J. M. Daugas, and H. Ueno, “β-NMR measurements of neutron-rich isotopes for nuclear structure and materials science,”
The 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022), Daejeon, Korea, October
3–7, 2022.
P. Schury (oral), D. Kaji, M. Wada, T. Niwase, S. Kimura, H. Koura, H. Miyatake, H. Ishiyama, K. Morimoto, M. Rosenbusch,
A. Takamine, Y. Hirayama, Y. Ito, Y. X. Watanabe, P. Brionnet, and H. Wollnik, “Multi-reﬂection time-of-ﬂight mass spectroscopyof superheavy nuclides,” The 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022),
Daejeon, Korea, October 3–7, 2022.
J. Y. Moon (poster), M. Wada, P. Schury, T. Hashimoto, Y. X. Watanabe, Y. Hirayama, M. Rosenbusch, Y. Ito, S. Iimura, J. Lee,
S. Kimura, Z. Korkulu, H. Miyatake, T. Niwase, A. Takamine, and H. Wollnik, “Construction of the Multi-reﬂection time-of-ﬂight
mass spectrograph (MRTOF-MS) at RAON,” The 19th International Conference on Electromagnetic Isotope Separators and Related
Topics (EMIS 2022), Daejeon, Korea, October 3–7, 2022.
M. Mukai (oral), “Laser ionization spectroscopy of neutron-rich Ir isotopes and recent works at KISS,” Workshop on Laser Spectroscopy/Analysis of Radioactive Isotope and Related Topics, Nagoya, Japan, October 20, 2022.
M. A. Syakuur (poster), A. R. Noviyanti, U. Widyaiswari, T. Saragi, Risdiana, and I. Watanabe, “Sample synthesis of a single phase
Nd2 Ru2 O7 ,” Asia-Paciﬁc Conference on Condensed Matter Physics 2022 (AC2MP2022), Sendai, Japan & Online (Hybrid), November 21–23, 2022.
M. A. Syakuur (poster), A. R. Noviyanti, A. R. Noviyanti, U. Widyaiswari, T. Saragi, Risdiana, D. P. Sari, H. Sakai, N. Hanasaki, andI. Watanabe, “Sample synthesis of a single phase Nd2 Ru2 O7 ,” The 6th International Conference on Functional Materials Science 2022
(ICFMS 2022), Bali, Indonesia & Online (Hybrid), November 29–30, 2022.
T. Otsuka (invited), “Emerging of alpha clustering due to nuclear forces,” Mean-ﬁeld and Cluster Dynamics in Nuclear Systems 2022
(MCD2022) First Week, Kyoto, Japan & Online (Hybrid), May 9–13, 2022.
T. Otsuka (invited), “Alpha clustering from ﬁrst principles for Be and C isotopes including the Hoyle state,” 8th Workshop on Level
Density and Gamma Strength, Oslo, Norway, May 9–13, 2022.
T. Otsuka (oral), “New facets of alpha-clustering and deformation towards driplines depicted by nuclear forces,” Mean-ﬁeld and Cluster
Dynamics in Nuclear Systems 2022 (MCD2022) Third Week, Kyoto, Japan & Online (Hybrid), May 23–27, 2022.
T. Otsuka (invited), “Emerging concepts in nuclear structure based on the shell model,” Symposium “Frontiers in Nuclear Structure
Theory” on the Occasion of the 90th Birthday of Prof. Jan Blomquist, Online, May 23–25, 2022.
T. Otsuka (invited), “Prevailing triaxiality of heavy deformed nuclei,” Shapes and Symmetries in Nuclei: from Experiment to Theory(SSNET’22), Paris, France, May 30–June 3, 2022.
T. Otsuka (invited), “Structure evolutions towards neutron driplines,” Mean-ﬁeld and Cluster Dynamics in Nuclear Systems 2022
(MCD2022) Fifth Week, Kyoto, Japan, June 6–10, 2022.
T. Otsuka (invited), “Monopole-quadrupole interplay in nuclear structure and resulting self-organization phenomena,” Mean-ﬁeld andCluster Dynamics in Nuclear Systems 2022 (MCD2022) Sixth Week, Kyoto, Japan & Online (Hybrid), June 13–17, 2022.
T. Otsuka (oral), “What locates neutron driplines?” Direct Reactions with Exotic Beams 2022 (DREB2022), Santiago de Compostela,
Spain, June 27–July 1, 2022.
T. Otsuka (invited), “Prevailing triaxiality in nuclear shapes,” 55th Zakopane Conference on Nuclear Physics, Zakopane, Poland, August
29–September 2, 2022.
T. Otsuka (invited), “Shell evolution and emerging paradigm changes,” 28th International Nuclear Physics Conference (INPC 2022), CapeTown, South Africa, September 11–16, 2022.
T. Otsuka (invited), “Prevailing triaxiality in heavy deformed nuclei and possible experimental observation by M1 excitation,” SFB 1245
Annual Workshop, Darmstadt, Germany, October 4–7, 2022.
T. Otsuka (invited), “Knocking out nucleons and alphas to see novel nuclear structures,” REIMEI Workshop “Unveiling Nuclear Shells
and Correlations in Exotic Nuclei through Knockout Reactions,” Darmstadt, Germany, October 10–12, 2022.

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T. Otsuka (invited), “(A) Triaxial ellipsoids probed by the RHC and a possible paradigm change in nuclear structure (B) Progress report on96
Zr and 96 Ru,” EMMI Rapid Reaction Task Force (RRTF) “Nuclear physics Confronts Relativistic Collisions of Isobars,” Heidelberg,
Germany, October 12–14, 2022.
T. Otsuka (invited), “Prevailing triaxiality driven by the tensor force,” The 6th Topical Workshop on Modern Aspects in Nuclear Structure(BORMIO-2023), Bormio, Italy, February 6–11, 2022.
T. Otsuka (invited), “New aspects of nuclear structure (Impacts from modern Shell Model),” INTPART School 2023, Okinawa, Japan,
February 20–March 3, 2023.

[Domestic Conferences/Workshops]

今村慧 (依頼講演), 「RI 原子線共鳴装置の開発:イオントラップ部」, 新学術領域研究「宇宙観測検出器と量子ビームの出会い. 新
たな応用の架け橋. 」領域研究会 (第 4 回領域全体会議), オンライン, 2022 年 5 月 20–21 日.
上野秀樹 (依頼講演), 「計画研究 B03 班 高偏極 RI ビームの生成と核・物質科学研究への応用」, 新学術領域研究「宇宙観測検出器と量子ビームの出会い. 新たな応用の架け橋. 」領域研究会 (第 4 回領域全体会議), オンライン, 2022 年 5 月 20–21 日.
光安陸大, 高峰愛子, 今村慧, 秋元彩, 伊藤愛美, 螺良健太, 菊地快, 上野秀樹, 松尾由賀利, 「加速器実験における超流動ヘリウム中
Rb 原子励起用レーザーのスペクトル最適化」, 第 18 回原子・分子・光科学 (AMO) 討論会, 東京 (東京大学本郷キャンパス) & オ
ンライン ハイブリッド開催, 2022 年 6 月 10–11 日.
菊地快, 今村慧, 高峰愛子, 螺良健太, 秋元彩, 伊藤愛美, 光安陸大, A. Gladkov, 田島美典, 郷慎太郎, 向井もも, 遠藤宏紀, 長谷正司,
川田敬太, 西畑洸希, 市川雄一, 北川敦志, 涌井崇志, 上野秀樹, 松尾由賀利, 「超流動ヘリウム中レーザー分光のための不安定核
原子 84 Rb の停止位置最適化」, 第 18 回原子・分子・光科学 (AMO) 討論会, 東京 (東京大学本郷キャンパス) & オンライン ハイ
ブリッド開催, 2022 年 6 月 10–11 日.
遠藤宏紀, 石井邦彦, 今村慧, 高峰愛子, 竹内由衣花, 田原太平, 上野秀樹, 松尾由賀利, 「超流動ヘリウム中 Rb 原子バブル緩和時間測定に向けたスペクトル解析」, 第 18 回原子・分子・光科学 (AMO) 討論会, 東京 (東京大学本郷キャンパス) & オンライン ハイ
ブリッド開催, 2022 年 6 月 10–11 日.
大塚孝治, 「炭素 12 の第一原理計算とホイル状態」, RCNP 研究会「原子核反応研究の最近の話題と展望」 河合光路先生を偲ぶ会,
大阪府茨木 (大阪大学吹田キャンパス), 2022 年 7 月 8–9 日.
水野るり惠, 池田時浩, 郷慎太郎, 櫻井博儀, 齋藤岳志, 新倉潤, 松崎禎市郎, 道正新一郎, 「1 MeV 陽子ビームを用いた広ダイナミッ
クレンジ光子検出器の性能評価実験」, 第 34 回タンデム加速器及びその周辺技術の研究会, オンライン, 2022 年 7 月 21–22 日.
安藤蒼太, 市川雄一, 佐藤智哉, 篠原雄介, 西畑洸希, 岸本侃己, 山下渉, 横田望海, 立川柊平, 竹中京平, 梶原孝文, 荒殿和希, 郷慎太郎,
高峰愛子, 上野秀樹, 旭耕一郎, 「EDM 測定に向けたガラスセル中 Xe 原子のスピン緩和機構の評価 II」, 日本物理学会 2022 年
秋季大会, 岡山市 (岡山理科大学岡山キャンパス), 2022 年 9 月 6–8 日.
篠原悠介, 市川雄一, 郷慎太郎, 西畑洸希, 安藤蒼太, 荒殿和希, 旭耕一郎, 馬場秀忠, 福田直樹, G. Georgiev, A. Gladkov, 今村慧,梶原孝文, 岸本侃己, R. Lozeva, 向井もも, 新倉潤, M. N. Nurhaﬁza, 小田原厚子, 清水陽平, M. Si, K. Stoychev, 鈴木宏, 立川柊平,
田島美典, 高峰愛子, 竹田浩之, 竹中京平, 武重祥子, 上野秀樹, 若狭智嗣, 山下渉, 山崎展樹, 横田望海, 吉本雅浩, J. -M. Daugas,「分散整合二回散乱法による 99 Zr アイソマー状態のスピン整列」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学岡山キャンパス), 2022 年 9 月 6–8 日.
向井もも, 平山賀一, 渡邉裕, P. Schury, S. C. Jeong, 宮武宇也, 庭瀬暁隆, 小柳津充宏, M. Rosenbusch, 上野秀樹, 和田道治, 「MRTOFと組み合わせた崩壊核分光のための飛行時間検出器の開発」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学岡山キャンパス), 2022 年 9 月 6–8 日.
飯村俊, M. Rosenbusch, 高峰愛子, 和田道治, S. Chen, D. Hou, J. Liu, W. Xian, S. Yan, P. Schury, 木村創大, 庭瀬暁隆, 伊藤由太,
園田哲, 小島隆夫, 渡辺裕, 平山賀一, 宮武宇也, S. Naimi, 道正新一郎, 西村俊二, 小田原厚子, 石山博恒, 角田佑介, 清水則孝,
大塚孝治, 「理研 BigRIPS SLOWRI における ZD-MRTOF 装置を用いた中性子過剰 Sc, Ti, V 核の系統的核構造研究」, 日本
物理学会 2022 年秋季大会, 岡山市 (岡山理科大学岡山キャンパス), 2022 年 9 月 6–8 日.
鈴木大介, 小山俊平, Assié, M., L. Lalanne, O. Sorlin, 阿部喬, D. Beaumel, Y. Blumenfeld, L. Caceres, de Oliveira F. Santos,
F. Delaunay, F. Flavigny, S. Franchoo, J. Gibelin, Girard-V. Alcindor, J. Guillot, F. Hammache, O. Kamalou, A. Kamenyero,
北村徳隆, V. Lapoux, A. Lemasson, A. Matta, B. Mauss, P. Morfouace, 新倉潤, 大津秀暁, J. Pancin, T. Roger, 齋藤岳志, 櫻井博儀,
C. Stodel, and J. -C. Thomas, 「非束縛核 8 C におけるミラー対称性の研究」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学岡山キャンパス), 2022 年 9 月 6–8 日.
平山賀一, 向井もも, 渡辺裕, P. Schury, S. C. Jeong, 庭瀬暁隆, 小柳津充広, M. Rosenbusch, 谷口秋洋, 宮武宇也, 和田道治, 「KISS での低温ヘリウムガスセル開発」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学岡山キャンパス), 2022 年 9 月 6–8 日.
庭瀬暁隆, 渡辺裕, 平山賀一, 向井もも, P. Schury, N. Andreyev, 飯村俊, 石山博恒, S. C. Jeong, 宮武宇也, M. Rosenbusch, 谷口秋洋,
和田道治, 「精密質量測定による新同位体 241 U の発見」
, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学岡山キャンパス),
2022 年 9 月 6–8 日.
洲嵜ふみ, 西尾勝久, A. N. Andreyev, 廣瀬健太郎, R. Orlandi, 牧井宏之, J. Smallcombe, 伊藤由太, 浅井雅人, 塚田和明, 佐藤哲也,
小川達彦, 宮武宇也, 渡邉裕, 平山賀一, S. C. Jeong, 向井もも, 庭瀬暁隆, 久保野茂, 岩佐直仁, 「JAEA 反跳生成核分離装置を用いた多核子移行反応の研究」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学岡山キャンパス), 2022 年 9 月 6–8 日.
角田佑介, 清水則孝, 大塚孝治, 「モンテカルロ殻模型による N = 50 近傍の核構造の研究」, 日本物理学会 2022 年秋季大会, 岡山市(岡山理科大学岡山キャンパス), 2022 年 9 月 6–8 日.
阿部喬 (基調講演), 「富岳で探る炭素 12 のホイル状態」, 富岳で加速する素粒子・原子核・宇宙・惑星シンポジウム, 神戸大学先端融合研究環統合研究拠点 & オンライン ハイブリッド開催, 2022 年 12 月 12–13 日.
阿部喬, 「モンテカルロ殻模型による第一原理計算の最近の進展」, 富岳で加速する素粒子・原子核・宇宙・惑星シンポジウム, オ
ンライン, 2022 年 1 月 17–18 日
小澤直也, 長濱弘季, 中村圭佑, 佐藤幹, 中下輝士, 永瀬慎太郎, 上原大祐, 深瀬実来, 青木貴稔, 山口敦史, 高峰愛子, 上野秀樹,- 257 -

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RIKEN Accel. Prog. Rep. 56 (2023)

酒見泰寛, 「永久電気双極子能率探索を目指した冷却フランシウム原子源の開発」, 日本物理学会 2023 年春季大会, オンラ
イン, 2023 年 3 月 22–25 日.
深瀬実来, 長濱弘季, 中村圭佑, 小澤直也, 佐藤幹, 中下輝士, 永瀬慎太郎, 上原大祐, 高峰愛子, 上野秀樹, 酒見泰寛, 「フランシウ
ム原子の永久電気双極子能率探索に向けた高周波二重極質量フィルターの開発」, 日本物理学会 2023 年春季大会, オンライン,
2023 年 3 月 22–25 日.
上原大祐, 長濱弘季, 中村圭佑, 佐藤幹, 中下輝士, 小澤直也, 永瀬慎太郎, 深瀬実来, 青木貴稔, 山口敦史, 高峰愛子, 上野秀樹,
酒見泰寛, 「レーザー冷却フランシウム源実現に向けた金属表面における中性脱離反応の研究」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
立川柊平, 市川雄一, 佐藤智哉, 安藤蒼太, 篠原悠介, 谷本昂平, 山本陽介, 西畑洸希, 若狭智嗣, 岸本侃己, 山下渉, 横田望海, 竹中京平,
梶原孝文, 荒殿和希, 郷慎太郎, 高峰愛子, 上野秀樹, 旭耕一郎, 「EDM 測定に向けた能動帰還型核スピンメーザーの開発」, 日本
物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
今村慧, 高峰愛子, 福澤悠亮, A. Gladkov, 郷慎太郎, 田島美典, 上野秀樹, 「原子ビーム共鳴法を利用したスピン偏極 RI 原子ビーム生成に向けた中性化装置開発」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
菊地快, 今村慧, 高峰愛子, 螺良健太, 秋元彩, 伊藤愛美, 光安陸大, A. Gladkov, 田島美典, 郷慎太郎, 向井もも, 遠藤宏紀, 長谷正司,
川田敬太, 西畑洸希, 市川雄一, 北川敦志, 涌井崇志, 上野秀樹, 松尾由賀利, 「レーザー誘起蛍光観測による超流動ヘリウム中不安定核原子 84 Rb の停止位置最適化」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
光安陸大, 高峰愛子, 今村慧, 秋元彩, 伊藤愛美, 螺良健太, 菊地快, 上野秀樹, 松尾由賀利, 「HIMAC における超流動ヘリウム中不安定核原子 84 Rb の蛍光検出高感度化の試み」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
向井もも, 平山賀一, 渡邉裕, P. Schury, S. C. Jeong, 宮武宇也, 庭瀬暁隆, M. Rosenbusch, 上野秀樹, 和田道治, 「安定イリジウム同位, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
体周辺核の直接質量測定」
田島美典, 黒田直史, 桧垣浩之, 松田恭幸 (ASACUSA-CUSP Collaboration), 「反陽子蓄積リング施設 ELENA における反陽子トラップ」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
阿部喬, 「第一原理計算によるホイル状態のクラスター構造」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
角田佑介, 清水則孝, 大塚孝治, 「モンテカルロ殻模型による N = 50 近傍の核構造の研究」, 日本物理学会 2023 年春季大会, オンラ
イン, 2023 年 3 月 22–25 日.
高峰愛子, 「原子物理分光技術で覗く原子核の世界」, 第 30 回原子衝突セミナー, オンライン, 2022 年 3 月 30–31 日.

Award
K. Kikuchi (Hosei Univ.), “Optimization of the stopping position of a highly energetic 84 Rb atoms injected into superﬂuid helium,” Poster
Award of the 29th International Conference on Low Temperature Physics (LT29), August 23, 2022.

Press Releases

プレスリリース: 「スーパーコンピュータ『富岳』で探る炭素の起源―第一原理計算で導かれたアルファクラスターの構造」, 理研, 東京大学, 日本原子力研究開発機構共同プレスリリース, 2022 年 4 月 27 日.
新聞掲載: 「理研, C12 原子核の量子構造解明 炭素起源理解に期待」, 日刊工業新聞, 2022 年 4 月 28 日.

Outreach Activities

アウトリーチ: 高峰愛子 (理研), インタビュー記事 Web 掲載 (高校・大学生向けイベント) 「見たい! 知りたい! 原子核サイエンス最前線仁科加速器科学研究センター応援団」, 2022 年 7 月 1 日.
理研広報誌掲載: 「炭素はどのようにしてつくられたのか」, 理研クローズアップ科学道 2022 (理研, 2022 年 9 月 12 日).
理研広報誌掲載: “Calculations reveal three helium nuclei lurking inside carbon nuclei,” RIKEN Research (RIKEN, Winter 2022 issue),p. 14.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Nuclear Science and Transmutation Research DivisionHigh Energy Astrophysics Laborarory
1. Abstract

In the immediate aftermath of the Big Bang, the beginning of our universe, only hydrogen and helium existed. However, nuclear
fusion in the interior of stars and the explosion of supernovae in the universe over 13.8 billion years led to the evolution of a world
brimming with the many diﬀerent elements we have today. By using scientiﬁc satellites or balloons to observe X-rays and gamma-rays
emitted from celestial objects, we are observing the synthesis of the elements at their actual source. Our goal is to comprehensively
elucidate the scenarios for the formation of the elements in the universe, together with our research on sub-atomic physics through theuse of an accelerator.

2. Major Research Subjects
(1)
(2)
(3)
(4)

History of nucleosynthesis in the universe
Physics in extreme conditions in the universe
Research and development of innovative radiation detectors
Apply radiation technology for human to live in space

3. Summary of Research Activity

High Energy Astrophysics Laboratory started in April 2010. The goal of our research is to reveal the mechanism of nucleosynthesis and the evolution of elements in the universe, and to observe/discover exotic physical phenomena in extremely strong magnetic
and/or gravitational ﬁelds. We have observed supernova remnants, strongly magnetized neutron stars, pulsars, black holes and galaxies
with X-ray astronomical satellites, balloons and ground-based telescopes.
(1) Nucleosynthesis in the universe(1-1) XRISM
X-Ray Imaging and Spectroscopy Mission (XRISM) is a new X-ray astrophysics observatory developed by a joint eﬀort between
Japan and US with the participation of Europe. XRISM aims to recover the high-resolution X-ray spectroscopy of hot plasma in the
Universe initiated by the short-lived Hitomi satellite, which was lost in 2016 by accident one month after the launch. In FY2022, thedevelopment and tests of the satellite have been completed successfully. XRISM is ready for launch in the summer of 2023. A major
milestone was also achieved in the science observation program. The observation targets for the Performance Veriﬁcation (PV) phasehave been selected and released to public and a new program called the XRISM Guest Scientist has started to oﬀer researchers in theastrophysics community an opportunity to participate in scientiﬁc activities with the observations in the PV phase.
(1-2) MAXI and OHMAN
Since April 2018, High Energy Astrophysics Laboratory has hosted MAXI (Monitor of All-sky X-ray Image) onboard International Space Station (ISS), which was attached to ISS in 2009. MAXI is a RIKEN-led project collaborating with JAXA and otheruniversities. Since MAXI scans X-ray all-sky every 90 minutes, many new transient objects, including outbursts of neutron stars or
blackhole binaries, can be found. All the data go public soon after they are taken, and almost all groups in high-energy phenomena rely on the MAXI data. In FY2022, MAXI has directly linked to NICER (Neutron Star Interior Composition Explorer; highly
sensitive X-ray detector but narrow ﬁeld of view) operated by the US on the ISS (the OHMAN project; On-orbit Hookup of MAXI
And NICER). The connection was completed in August 2022 after a few years of preparation and has successfully transferred MAXItransient discovery alerts to NICER in as little as 100 s. Detections associated with the neutron star merger event have yet to be madebut are ready to respond anytime.
(2) Extremely strong magnetism and gravity(2-1) IXPE
We have contributed to NASA’s world-ﬁrst X-ray polarimeter mission IXPE (Imaging X-ray Polarimeter Explorer). High Energy
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 is produced based on our patent for space use. The IXPE satellite was successfully launched from
Florida on December 9, 2021. After one month of commissioning in orbit, IXPE started scientiﬁc observations of X-ray stellar objects
on January 11, 2022. The international science team has written over 30 discovery papers (including 3 Nature and 2 Science papers)
during 1.5 years of operation.
Using the IXPE mission, we aim to prove the strong magnetism of Magnetars, one of the species of neutron stars with 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 ignored in the
QED perturbation theory. As a result, we observe newly-emerging phenomena such as vacuum polarization, vacuum birefringence,etc. The RIKEN team is the core member of the science working group on Magnetars, leading observations and data analysis. In
4U 0142+61 Magnetar observation, we have conﬁrmed that the results are consistent with the model with an ultra-strong magnetic
ﬁeld above 1010 T. We have also discovered that contrary to theoretical expectations, there is no atmosphere on the magnetar surface,
and the condensed surface is exposed to space (press released at RIKEN). This may be because the atmosphere condenses due to thestrong magnetic ﬁeld. The further study of a strong magnetic ﬁeld, one of the key parameters of neutron stars, hints at the study ofneutron star nuclear matter.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)(2-2) Astrophysical data analysis
In parallel with the mission development/operations, we are studying gamma-ray binary systems, which are one of the mostimportant astrophysical targets in the MeV gamma-ray band. We analyzed the broad-band emission of gamma-ray binary LS 5039,
a bright gamma-ray object in the MeV band, using NuSTAR and Fermi. The obtained spectrum with the highest available statistics
shows that the emission from MeV to sub-GeV bands is diﬃcult to explain with current theoretical models, suggesting particle
acceleration there is much more eﬃcient than well-known standard diﬀusive shock acceleration.
(3) Innovative breakthrough in astrophysics with a small satellite
We are developing technology and acquiring the know-how to make space observation, which requires a lot of money, possible
with small satellites at a low cost. NASA and other space agencies around the world have realized the importance of these opportunities
and have started space observation activities using small satellites. NinjaSat is a micro-satellite mission (6U CubeSat; 30×20×10 cm3 )led by RIKEN in collaboration with universities. NinjaSat will be launched on October 2023. Although several science missions haverecently been conducted using micro-satellites, NinjaSat is the world’s ﬁrst general-purpose CubeSat mission to observe X-ray sources.
NinjaSat carries two Xe-ﬁlled gas detectors with 2-degree-wide collimators and performs spectroscopy between 2–50 keV and timing
observation with a timing resolution of about 61 µs. Since the eﬀective area is not large (∼32 cm2 at 6 keV), the target of the NinjaSat
is long-term monitoring of bright X-ray sources which are discovered by MAXI etc. In general, bright objects are diﬃcult to observe,and continuous observations for a long period are impossible with large satellite missions. NinjaSat aims to perform observations
that are diﬃcult to perform on larger missions. For example, NinjaSat observes the time variability of binary neutron stars and binary
black holes in conjunction with the ground-based optical, radio, and gravitational telescopes. We installed the X-ray detectors into thesatellite bus in FY2022.
(4) Future X-ray and gamma-ray detectors
As an successor of the MAXI mission, we are also verifying the principle of a new concept, multiplexing lobster-eye (MuLE)
optics, to monitor the entire sky with a wide ﬁeld-of-view for detecting and immediate reporting transient objects such as a neutronstar merger. We published a paper on the conceptual design of MuL, and proved the concept by a simple experiment.
To explore the MeV gamma-ray sky in the Universe, we are working on the technical development of the GRAMS (Gamma-Ray
and AntiMatter Survey) project, which aims at future MeV gamma-ray observations with a Compton telescope using a liquid argon
time projection chamber. We developed two types of event reconstruction algorithms for multiple Compton scattering events using
probabilistic and neural network methods. Based on them, we conﬁrmed that the advantage of the GRAMS project, which is anobservation with an eﬀective area larger than previous by 1-2 orders magnitudes, can be achievable with a current mission concept.

Members
Director
Toru TAMAGAWA
Research/Technical Scientist
Tatehiro MIHARA (Senior Research Scientist)
Special Postdoctoral Researcher
Hiroki YONEDA
Visiting Scientists
Aya BAMBA (Univ. of Tokyo)
Naohisa INADA (NIT, Nara College)
Satoru KATSUDA (Saitama Univ.)
Tomoko KAWATE (Nat’l Inst. of Natural Sci.)
Tomoki KIMURA (Tokyo Univ. Sci.)
Kazuki KOMIYA (Tokyo Metroporitan Industrial Tech. Res.
Inst.)
Toru MISAWA (Shinshu Univ.)
Ikuyuki MITSUISHI (Nagoya Univ.)
Yujin NAKAGAWA (JAMSTEC)
Nobuyuki NAKAMURA (Univ. of Electro-Commun.)
Hirofumi NODA (Osaka Univ.)
Hirokazu ODAKA (Univ. of Tokyo)

Yuki OKURA (NAOJ/Nat’l Inst. of Natural Sci.)
Hiroyuki SAKAUE (Nat’l Inst. of Natural Sci.)
Rohta TAKAHASHI (NIT, Tomakomai College)
Yoko TAKEUCHI (Tokyo Metroporitan Industrial Tech. Res.
Inst.)
Takaaki TANAKA (Konan Univ.)
Yukikatsu TERADA (Saitama Univ.)
Masahiro TSUJIMOTO (JAXA)
Hiroyuki UCHIDA (Kyoto Univ.)
Masaki WAKABAYASHI (Jakulin Commercial Company LC)
Shinya YAMADA (Rikkyo Univ.)
Hiroya YAMAGUCHI (JAXA)

Student Trainees
Yuki AMANO (Kyoto Univ.)
Syoki HAYASHI (Tokyo Univ. Sci)
Arata JUJO (Tokyo Univ. Sci)
Miki KURIHARA (Univ. of Tokyo)
Yuken OHSHIRO (Univ. of Tokyo)
Naoyuki OTA (Tokyo Univ. Sci)

Satoshi TAKASHIMA (Univ. of Tokyo)
Moto TOGAWA (Univ. of Heidelberg)
Keisuke UCHIYAMA (Tokyo Univ. Sci)
Sota WATANABE (Tokyo Univ. Sci)
Yuanhui ZHOU (Tokyo Univ. Sci)

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RIKEN Accel. Prog. Rep. 56 (2023)

Research Part-time Worker
Naoyuki OTA (Tokyo Univ. Sci)

List of Publications & Presentations
Publications[Original Papers]
M. C. Weisskopf, P. Soﬃtta, L. Baldini, B. D. Ramsey, S. L. O’Dell, R. W. Romani, G. Matt, W. D. Deininger, W. H. Baumgartner,
R. Bellazzini, E. Costa, J. J. Kolodziejczak, L. Latronico, H. L. Marshall, F. Muleri, S. D. Bongiorno, A. Tennant, N. Bucciantini,
M. Dovciak, F. Marin, A. Marscher, J. Poutanen, P. Slane, R. Turolla, W. Kalinowski, A. D. Marco, S. Fabiani, M. Minuti, F. L. Monaca,
M. Pinchera, J. Rankin, C. Sgrò, A. Trois, F. Xie, C. Alexander, D. Z. Allen, F. Amici, J. Andersen, A. Antonelli, S. Antoniak, P. Attiná,
M. Barbanera, M. Bachetti, R. M. Baggett, J. Bladt, A. Brez, R. Bonino, C. Boree, F. Borotto, S. Breeding, D. Brienza, H. K. Bygott,
C. Caporale, C. Cardelli, R. Carpentiero, S. Castellano, M. Castronuovo, L. Cavalli, E. Cavazzuti, M. Ceccanti, M. Centrone, S. Citraro,
F. D’Amico, E. D’Alba, L. D. Gesu, E. D. Monte, K. L. Dietz, N. D. Lalla, G. D. Persio, D. Dolan, I. Donnarumma, Y. Evangelista,
K. Ferrant, R. Ferrazzoli, M. Ferrie, J. Footdale, B. Forsyth, M. Foster, B. Garelick, S. Gunji, E. Gurnee, M. Head, G. Hibbard,
S. Johnson, E. Kelly, K. Kilaru, C. Lefevre, S. L. Roy, P. Loﬀredo, P. Lorenzi, L. Lucchesi, T. Maddox, G. Magazzu, S. Maldera,A. Manfreda, E. Mangraviti, M. Marengo, A. Marrocchesi, F. Massaro, D. Mauger, J. McCracken, M. McEachen, R. Mize, P. Mereu,
S. Mitchell, I. Mitsuishi, A. Morbidini, F. Mosti, H. Nasimi, B. Negri, M. Negro, T. Nguyen, I. Nitschke, A. Nuti, M. Onizuka,
C. Oppedisano, L. Orsini, D. Osborne, R. Pacheco, A. Paggi, W. Painter, S. D. Pavelitz, C. Pentz, R. Piazzolla, M. Perri, M. PesceRollins, C. Peterson, M. Pilia, A. Profeti, S. Puccetti, J. Ranganathan, A. Ratheesh, L. Reedy, N. Root, A. Rubini, S. Ruswick,
J. Sanchez, P. Sarra, F. Santoli, E. Scalise, A. Sciortino, C. Schroeder, T. Seek, K. Sosdian, G. Spandre, C. O. Speegle, T. Tamagawa,M. Tardiola, A. Tobia, N. E. Thomas, R. Valerie, M. Vimercati, A. L. Walden, B. Weddendorf, J. Wedmore, D. Welch, D. Zanetti, andF. Zanetti, “Imaging X-ray polarimetry explorer: prelaunch,” J. Astron. Telesc. Instrum. Syst. 8, 026002 (2022).
R. Taverna, R. Turolla, F. Muleri, J. Heyl, S. Zane, L. Baldini, D. Gonzalez-Caniulef, M. Bachetti, J. Rankin, I. Caiazzo, N. D. Lalla,
V. Doroshenko, M. Errando, E. Gau, D. Kırmızıbayrak, H. Krawczynski, M. Negro, M. Ng, N. Omodei, A. Possenti, T. Tamagawa,K. Uchiyama, M. C. Weisskopf, I. Agudo, L. A. Antonelli, W. H. Baumgartner, R. Bellazzini, S. Bianchi, S. D. Bongiorno, R. Bonino,
A. Brez, N. Bucciantini, F. Capitanio, S. Castellano, E. Cavazzuti, S. Ciprini, E. Costa, A. D. Rosa, E. D. Monte, L. D. Gesu,
A. D. Marco, I. Donnarumma, M. Dovˇciak, S. R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, R. Ferrazzoli, J. A. Garcia, S. Gunji,
K. Hayashida, W. Iwakiri, S. G. Jorstad, V. Karas, T. Kitaguchi, J. J. Kolodziejczak, F. L. Monaca, L. Latronico, I. Liodakis, S. Maldera,A. Manfreda, F. Marin, A. Marinucci, A. P. Marscher, H. L. Marshall, G. Matt, I. Mitsuishi, T. Mizuno, S. C. -Y. Ng, S. L. O’Dell,
C. Oppedisano, A. Papitto, G. G. Pavlov, A. L. Peirson, M. Perri, M. Pesce-Rollins, M. Pilia, J. Poutanen, S. Puccetti, B. D. Ramsey, A. Ratheesh, R. W. Romani, C. Sgr‘o, P. Slane, P. Soﬃtta, G. Spandre, F. Tavecchio, Y. Tawara, A. F. Tennant, N. E. Thomas,
F. Tombesi, A. Trois, S. S. Tsygankov, J. Vink, K. Wu, and F. Xie, “Polarized X-rays from a magnetar,” Science 378, 646 (2022).
I. Liodakis, A. P. Marscher, I. Agudo, A. V. Berdyugin, M. I. Bernardos, G. Bonnoli, G. A. Borman, C. Casadio, V. Casanova, E. Cavazzuti,
N. R. Cavero, L. D. Gesu, N. D. Lalla, I. Donnarumma, S. R. Ehlert, M. Errando, J. Escudero, M. Garcıa-Comas, B. Agıs-González,
C. Husillos, J. Jormanainen, S. G. Jorstad, M. Kagitani, E. N. Kopatskaya, V. Kravtsov, H. Krawczynski, E. Lindfors, E. G. Larionova, G. M. Madejski, F. Marin, A. Marchini, H. L. Marshall, D. A. Morozova, F. Massaro, J. R. Masiero, D. Mawet, R. Middei,
M. A. Millar-Blanchaer, I. Myserlis, M. Negro, K. Nilsson, S. L. O’Dell, N. Omodei, L. Pacciani, A. Paggi, G. V. Panopoulou,
A. L. Peirson, M. Perri, P. -O. Petrucci, J. Poutanen, S. Puccetti, R. W. Romani, T. Sakanoi, S. S. Savchenko, A. Sota, F. Tavecchio,
S. Tinyanont, A. A. Vasilyev, Z. R. Weaver, A. V. Zhovtan, L. A. Antonelli, M. Bachetti, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, S. D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, F. Capitanio, S. Castellano, S. Ciprini, E. Costa, A. D. Rosa,
E. D. Monte, A. D. Marco, V. Doroshenko, M. Dovˇciak, T. Enoto, Y. Evangelista, S. Fabiani, R. Ferrazzoli, J. A. Garcia, S. Gunji,
K. Hayashida, J. Heyl, W. Iwakiri, V. Karas, T. Kitaguchi, J. J. Kolodziejczak, F. L. Monaca, L. Latronico, S. Maldera, A. Manfreda,
A. Marinucci, G. Matt, I. Mitsuishi, T. Mizuno, F. Muleri, S. C. -Y. Ng, C. Oppedisano, A. Papitto,G. G. Pavlov, M. Pesce-Rollins,
M. Pilia, A. Possenti, B. D. Ramsey, J. Rankin, A. Ratheesh, C. Sgró, P. Slane, P. Soﬃtta, G. Spandre, T. Tamagawa, R. Taverna,
Y. Tawara, A. F. Tennant, N. E. Thomas, F. Tombesi, A. Trois, S. Tsygankov, R. Turolla, J. Vink, M. C. Weisskopf, K. Wu, F. Xie, andS. Zane, “Polarized blazar X-rays imply particle acceleration in shocks,” Nature 611, 677 (2022).
S. R. Ehlert, R. Ferrazzoli, A. Marinucci, H. L. Marshall, R. Middei, L. Pacciani, M. Perri, P. -O. Petrucci, S. Puccetti, T. Barnouin,
S. Bianchi, I. Liodakis, G. Madejski, F. Marin, A. P. Marscher, G. Matt, J. Poutanen, K. Wu, I. Agudo, L. A. Antonelli, M. Bachetti,
L. Baldini, W. H. Baumgartner, R. Bellazzini, S. D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, F. Capitanio, S. Castellano,
E. Cavazzuti, S. Ciprini, E. Costa, A. D. Rosa, E. D. Monte, L. D. Gesu, N. D. Lalla, A. D. Marco, I. Donnarumma, V. Doroshenko,
M. Dovˇciak, T. Enoto, Y. Evangelista, S. Fabiani, J. A. Garcia, S. Gunji, K. Hayashida, J. Heyl, W. Iwakiri, S. G. Jorstad, V. Karas,
T. Kitaguchi, J. J. Kolodziejczak, H. Krawczynski, F. L. Monaca, L. Latronico, S. Maldera, A. Manfreda, F. Massaro, I. Mitsuishi,
T. Mizuno, F. Muleri, M. Negro, C. -Y. Ng, S. L. O’Dell, N. Omodei, C. Oppedisano, A. Papitto, G. G. Pavlov, A. L. Peirson, M. PesceRollins, M. Pilia, A. Possenti, B. D. Ramsey, J. Rankin, A. Ratheesh, R. W. Romani, C. Sgr‘o, P. Slane, P. Soﬃtta, G. Spandre,
T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara, A. F. Tennant, N. E. Thomas, F. Tombesi, A. Trois, S. Tsygankov, R. Turolla,
J. Vink, M. C. Weisskopf, F. Xie, S. Zane, J. Rodi, E. Jourdain, and J. -P. Roques, “Limits on X-ray polarization at the core of centaurus
A as observed with the imaging X-ray polarimetry explorer,” Astrophys. J. 935, 116 (2022).
V. Doroshenko, J. Poutanen, S. S. Tsygankov, V. F. Suleimanov, M. Bachetti, I. Caiazzo, E. Costa, A. D. Marco, J. Heyl, F. L. Monaca,
F. Muleri, A. A. Mushtukov, G. G. Pavlov, B. D. Ramsey, J. Rankin, A. Santangelo, P. Soﬃtta, R. Staubert, M. C. Weisskopf, S. Zane,
I. Agudo, L. A. Antonelli, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, S. D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, F. Capitanio, S. Castellano, E. Cavazzuti, S. Ciprini, A. D. Rosa, E. D. Monte, L. D. Gesu, N. D. Lalla, I. Donnarumma,
M. Dovčiak, S. R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, R. Ferrazzoli, J. A. Garcia, S. Gunji, K. Hayashida, W. Iwakiri,- 261 -

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S. G. Jorstad, V. Karas, T. Kitaguchi, J. J. Kolodziejczak, H. Krawczynski, L. Latronico, I. Liodakis, S. Maldera, A. Manfreda, F. Marin,
A. Marinucci, A. P. Marscher, H. L. Marshall, G. Matt, I. Mitsuishi, T. Mizuno, C. -Y. Ng, S. L. O’Dell, N. Omodei, C. Oppedisano,
A. Papitto, A. L. Peirson, M. Perri, M. Pesce Rollins, M. Pilia, A. Possenti, S. Puccetti, A. Ratheesh, R. W. Romani, C. Sgr‘o, P. Slane,
G. Spandre, R. A. Sunyaev, T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara, A. F. Tennant, N. E. Thomas, F. Tombesi, A. Trois,
R. Turolla, J. Vink, K. Wu, and F. Xie, “Determination of X-ray pulsar geometry with IXPE polarimetry,” Nat. Astron. 6, 1433 (2022).
H. Krawczynski, F. Muleri, M. Dovčiak, A. Veledina, N. R. Cavero, J. Svoboda, A. Ingram, G. Matt, J. A. Garcia, V. Loktev, M. Negro,
J. Poutanen, T. Kitaguchi, J. Podgorný, J. Rankin, W. Zhang, A. Berdyugin, S. V. Berdyugina, S. Bianchi, D. Blinov, F. Capitanio,
N. D. Lalla, P. Draghis, S. Fabiani, M. Kagitani, V. Kravtsov, S. Kiehlmann, L. Latronico, A. A. Lutovinov, N. Mandarakas, F. Marin,
A. Marinucci, J. M. Miller, T. Mizuno, S. V. Molkov, N. Omodei, P. -O. Petrucci, A. Ratheesh, T. Sakanoi, A. N. Semena, R. Skalidis,
P. Soﬃtta, A. F. Tennant, P. Thalhammer, F. Tombesi, M. C. Weisskopf, J. Wilms, S. Zhang, I. Agudo, L. A. Antonelli, M. Bachetti,
L. Baldini, W. H. Baumgartner, R. Bellazzini, S. D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, S. Castellano, E. Cavazzuti,
S. Ciprini, E. Costa, A. D. Rosa, E. D. Monte, L. D. Gesu, A. D. Marco, I. Donnarumma, V. Doroshenko, S. R. Ehlert, T. Enoto,
Y. Evangelista, R. Ferrazzoli, S. Gunji, K. Hayashida, J. Heyl, W. Iwakiri, S. G. Jorstad, V. Karas, J. J. Kolodziejczak, F. L. Monaca,
I. Liodakis, S. Maldera, A. Manfreda, A. P. Marscher, H. L. Marshall, I. Mitsuishi, C. -Y. Ng, S. L. O’Dell, C. Oppedisano, A. Papitto,
G. G. Pavlov, A. L. Peirson, M. Perri, M. Pesce-Rollins, M. Pilia, A. Possenti, S. Puccetti, B. D. Ramsey, R. W. Romani, C. Sgr‘o,P. Slane, G. Spandre, T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara, N. E. Thomas, A. Trois, S. Tsygankov, R. Turolla, J. Vink,
K. Wu, F. Xie, and S. Zane, “Polarized X-rays constrain the disk-jet geometry in the black hole X-ray binary Cygnus X-1,” Science
378, 650 (2022).
J. Vink, D. Prokhorov, R. Ferrazzoli, P. Slane, P. Zhou, K. Asakura, L. Baldini, N. Bucciantini, E. Costa, A. D. Marco, J. Heyl, F. Marin,
T. Mizuno, C. -Y. Ng, M. Pesce-Rollins, B. D. Ramsey, J. Rankin, A. Ratheesh, C. Sgró, P. Soﬃtta, D. A. Swartz, T. Tamagawa,
M. C. Weisskopf, Y. -J. Yang, R. Bellazzini, R. Bonino, E. Cavazzuti, L. Costamante, N. D. Lalla, L. Latronico, S. Maldera, A. Manfreda, F. Massaro, I. Mitsuishi, N. Omodei, C. Oppedisano, S. Zane, I. Agudo, L. A. Antonelli, M. Bachetti, W. H. Baumgartner,
S. Bianchi, S. D. Bongiorno, A. Brez, F. Capitanio, S. Castellano, S. Ciprini, A. D. Rosa, E. D. Monte, L. D. Gesu, I. Donnarumma,
V. Doroshenko, M. Dovčiak, S. R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, J. A. Garcia, S. Gunji, K. Hayashida, W. Iwakiri,
S. G. Jorstad, V. Karas, T. Kitaguchi, J. J. Kolodziejczak, H. Krawczynski, F. L. Monaca, I. Liodakis, A. Marinucci, A. P. Marscher,
H. L. Marshall, G. Matt, F. Muleri, S. L. O’Dell, A. Papitto, G. G. Pavlov, A. L. Peirson, M. Perri, M. Pilia, A. Possenti, J. Poutanen,
S. Puccetti, R. W. Romani, G. Spandre, F. Tavecchio, R. Taverna, Y. Tawara, A. F. Tennant, N. E. Thomas, F. Tombesi, A. Trois,
S. Tsygankov, R. Turolla, K. Wu, and F. Xie, “X-ray polarization detection of cassiopeia A with IXPE,” Astrophys. J. 938, 40 (2022).
F. Xie, A. D. Marco, F. L. Monaca, K. Liu, F. Muleri, N. Bucciantini, R. W. Romani, E. Costa, J. Rankin, P. Soﬃtta, M. Bachetti,
N. D. Lalla, S. Fabiani, R. Ferrazzoli, S. Gunji, L. Latronico, M. Negro, N. Omodei, M. Pilia, A. Trois, E. Watanabe, I. Agudo,
L. A. Antonelli, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, S. D. Bongiorno, R. Bonino, A. Brez, F. Capitanio, S. Castellano, E. Cavazzuti, S. Ciprini, A. D. Rosa, E. D. Monte, L. D. Gesu, I. Donnarumma, V. Doroshenko, M. Dovčiak, S. R. Ehlert,
T. Enoto, Y. Evangelista, J. A. Garcia, K. Hayashida, J. Heyl, W. Iwakiri, S. G. Jorstad, V. Karas, T. Kitaguchi, J. J. Kolodziejczak,
H. Krawczynski, I. Liodakis, S. Maldera, A. Manfreda, F. Marin, A. Marinucci, A. P. Marscher, H. L. Marshall, F. Massaro, G. Matt,
I. Mitsuishi, T. Mizuno, C. -Y. Ng, S. L. O’Dell, C. Oppedisano, A. Papitto, G. G. Pavlov, A. L. Peirson, M. Perri, M. Pesce-Rollins,
P. -O. Petrucci, A. Possenti, J. Poutanen, S. Puccetti, B. D. Ramsey, A. Ratheesh, C. Sgró, P. Slane, G. Spandre, T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara, A. F. Tennant, N. E. Thomas, F. Tombesi, S. S. Tsygankov, R. Turolla, J. Vink, M. C. Weisskopf, K. Wu,
and S. Zane, “Vela pulsar wind nebula X-rays are polarized to near the synchrotron limit,” Nature 612, 658 (2022).
H. L. Marshall, M. Ng, D. Rogantini, J. Heyl, S. S. Tsygankov, J. Poutanen, E. Costa, S. Zane, C. Malacaria, I. Agudo, L. A. Antonelli,
M. Bachetti, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, S. D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, F. Capitanio, S. Castellano, E. Cavazzuti, S. Ciprini, A. D. Rosa, E. D. Monte, L. D. Gesu, N. D. Lalla, A. D. Marco, I. Donnarumma,
V. Doroshenko, M. Dovčiak, S. R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, R. Ferrazzoli, J. A. Garcia, S. Gunji, K. Hayashida,
W. Iwakiri, S. G. Jorstad, V. Karas, T. Kitaguchi, J. J. Kolodziejczak, H. Krawczynski, F. L. Monaca, L. Latronico, I. Liodakis,
S. Maldera, A. Manfreda, F. Marin, A. Marinucci, A. P. Marscher, G. Matt, I. Mitsuishi, T. Mizuno, F. Muleri, C. -Y. Ng, S. L. O’Dell,
N. Omodei, C. Oppedisano, A. Papitto, G. G. Pavlov, A. L. Peirson, M. Perri, M. Pesce Rollins, P. -O. Petrucci, M. Pilia, A. Possenti,
S. Puccetti, B. D. Ramsey, J. Rankin, A. Ratheesh, R. W. Romani, C. Sgr‘o, P. Slane, P. Soﬃtta, G. Spandre, T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara, A. F. Tennant, N. E. Thomas, F. Tombesi, A. Trois, R. Turolla, J. Vink, M. C. Weisskopf, K. Wu, F. Xie,
N. S. Schulz, and D. Chakrabarty, “Observations of 4U 1626-67 with the imaging X-ray polarimetry explorer,” Astrophys. J. 940, 70(2022).
A. Marinucci, F. Muleri, M. Dovciak, S. Bianchi, F. Marin, G. Matt, F. Ursini, R. Middei, H. L. Marshall, L. Baldini, T. Barnouin,
N. C. Rodriguez, A. De Rosa, L. Di Gesu, D. Harper, A. Ingram, V. Karas, H. Krawczynski, G. Madejski, C. Panagiotou, P. O. Petrucci,
J. Podgorny, S. Puccetti, F. Tombesi, A. Veledina, W. Zhang, I. Agudo, L. A. Antonelli, M. Bachetti, W. H. Baumgartner, R. Bellazzini,
S. D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, F. Capitanio, S. Castellano, E. Cavazzuti, S. Ciprini, E. Costa, E. Del Monte,
N. Di Lalla, A. Di Marco, I. Donnarumma, V. Doroshenko, S. R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, R. Ferrazzoli, J. A. Garcia,
S. Gunji, K. Hayashida, J. Heyl, W. Iwakiri, S. G. Jorstad, T. Kitaguchi, J. J. Kolodziejczak, F. La Monaca, L. Latronico, I. Liodakis,
S. Maldera, A. Manfreda, A. P. Marscher, I. Mitsuishi, T. Mizuno, C. -Y. Ng, S. L. O’Dell, N. Omodei, C. Oppedisano, A. Papitto,
G. G. Pavlov, A. L. Peirson, M. Perri, M. Pesce-Rollins, M. Pilia, A. Possenti, J. Poutanen, B. D. Ramsey, J. Rankin, A. Ratheesh,
R. W. Romani, C. Sgrš, P. Slane, P. Soﬃtta, G. Spandre, T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara, A. F. Tennant, N. E. Thomas,
A. Trois, S. S. Tsygankov, R. Turolla, J. Vink, M. C. Weisskopf, K. Wu, F. Xie, and S. Zane, “Polarization constraints on the X-ray
corona in Seyfert Galaxies: MCG-05-23-16,” Mon. Not. R. Astron. Soc. 516, 5907 (2022).
L. D. Gesu, I. Donnarumma, F. Tavecchio, I. Agudo, T. Barnounin, N. Cibrario, N. D. Lalla, A. D. Marco, J. Escudero, M. Errando,
S. G. Jorstad, D. E. Kim, P. M. Kouch, I. Liodakis, E. Lindfors, G. Madejski, H. L. Marshall, A. P. Marscher, R. Middei, F. Muleri,
I. Myserlis, M. Negro, N. Omodei, L. Pacciani, A. Paggi, M. Perri, S. Puccetti, L. A. Antonelli, M. Bachetti, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, S. D. Bongiorno, R. Bonino, A. Brez, N. Bucciantini, F. Capitanio, S. Castellano, E. Cavazzuti,
S. Ciprini, E. Costa, A. D. Rosa, E. D. Monte, V. Doroshenko, M. Dovčiak, S. R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, R. Fer-

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razzoli, J. A. Garcia, S. Gunji, K. Hayashida, J. Heyl, W. Iwakiri, V. Karas, T. Kitaguchi, J. J. Kolodziejczak, H. Krawczynski,
F. L. Monaca, L. Latronico, S. Maldera, A. Manfreda, F. Marin, A. Marinucci, F. Massaro, G. Matt, I. Mitsuishi, T. Mizuno, C. Y. Ng, S. L. O’Dell, C. Oppedisano, A. Papitto, G. G. Pavlov, A. L. Peirson, M. Pesce-Rollins, P. -O. Petrucci, M. Pilia, A. Possenti,
J. Poutanen, B. D. Ramsey, J. Rankin, A. Ratheesh, R. W. Romani, C. Sgr‘o, P. Slane, P. Soﬃtta, G. Spandre, T. Tamagawa, R. Taverna,
Y. Tawara, A. F. Tennant, N. E. Thomas, F. Tombesi, A. Trois, S. Tsygankov, R. Turolla, J. Vink, M. C. Weisskopf, K. Wu, F. Xie, andS. Zane, “The X-ray polarization view of mrk 421 in an average ﬂux state as observed by the imaging X-ray polarimetry explorer,”
Astrophys. J. Lett. 938, L7 (2022).
S. S. Tsygankov, V. Doroshenko, J. Poutanen, J. Heyl, A. A. Mushtukov, I. Caiazzo, A. D. Marco, S. V. Forsblom, D. GonzálezCaniulef, M. Klawin, F. L. Monaca, C. Malacaria, H. L. Marshall, F. Muleri, M. Ng, V. F. Suleimanov, R. A. Sunyaev, R. Turolla,
I. Agudo, L. A. Antonelli, M. Bachetti, L. Baldini, W. H. Baumgartner, R. Bellazzini, S. Bianchi, S. D. Bongiorno, R. Bonino, A. Brez,
N. Bucciantini, F. Capitanio, S. Castellano, E. Cavazzuti, S. Ciprini, E. Costa, A. D. Rosa, E. D. Monte, L. D. Gesu, N. D. Lalla,
I. Donnarumma, M. Dovčiak, S. R. Ehlert, T. Enoto, Y. Evangelista, S. Fabiani, R. Ferrazzoli, J. A. Garcia, S. Gunji, K. Hayashida,
W. Iwakiri, S. G. Jorstad, V. Karas, T. Kitaguchi, J. J. Kolodziejczak, H. Krawczynski, L. Latronico, I. Liodakis, S. Maldera, A. Manfreda, F. Marin, A. Marinucci, A. P. Marscher, G. Matt, I. Mitsuishi, T. Mizuno, C. -Y. Ng, S. L. O’Dell, N. Omodei, C. Oppedisano,
A. Papitto, G. G. Pavlov, A. L. Peirson, M. Perri, M. Pesce-Rollins, P. -O. Petrucci, M. Pilia, A. Possenti, S. Puccetti, B. D. Ramsey,
J. Rankin, A. Ratheesh, R. W. Romani, C. Sgr‘o, P. Slane, P. Soﬃtta, G. Spandre, T. Tamagawa, F. Tavecchio, R. Taverna, Y. Tawara,
A. F. Tennant, N. E. Thomas, F. Tombesi, A. Trois, J. Vink, M. C. Weisskopf, K. Wu, F. Xie, S. Zane, “The X-ray polarimetry view of
the accreting pulsar cen X-3,” Astrophys. J. Lett. 941, L14 (2022).
Q. Abarr, B. Beheshtipour, M. Beilicke, R. Bose, D. Braun, G. d. Geron- imo, P. Dowkontt, M. Errando, T. Gadson, V. Guarino, S. Heatwole, M. Hossen, N. Iyer, F. Kislat, M. Kiss, T. Kitaguchi, H. Krawczynski, J. Lanzi, S. Li, L. Lisalda, T. Okajima, M. Pearce,
Z. Peterson, L. Press, B. Rauch, G. Simburger, D. Stuchlik, H. Takahashi, J. Tang, N. Uchida, and A. West, “Performance of the
X-Calibur hard X-ray polarimetry mission during its 201819 long-duration balloon ﬂight,” Astron. J. 143, 102749 (2022).
K. Asai, T. Mihara, and M. Matsuoka, “Decades-long variations in NS-LMXBs observed with MAXI/GS, RXTE/ASM, and Ginga/ASM,”
Publ. Astron. Soc. Jpn. 74, 974 (2022).
M. Sugizaki, T. Mihara, K. Kobayashi, H. Negoro, M. Shidatsu, S. N. Pike, W. Iwakiri, S. Urabe, M. Serino, N. Kawai, M. Nakajima,
J. A. Kennea, and Z. Liu, “Discovery of a new supergiant fast X-ray transient MAXI J0709159 associated with the Be star LY Canis
Majoris,” Publ. Astron. Soc. Jpn. 74, 1131 (2022).
S. N. Pike, H. Negoro, J. A. Tomsick, M. Bachetti, M. Brumback, R. M. T. Connors, J. A. Garcı́a, B. Grefenstette, J. Hare, F. A. Harrison,
A. Jaodand, R. M. Ludlam, G. Mastroserio, T. Mihara, M. Shidatsu, M. Sugizaki, and R. Takagi, “MAXI and NuSTAR observations of
the faint X-ray transient MAXI J1848-015 in the GLIMPSE-C01 cluster,” Astrophys. J. 927, 190 (2022).

[Proceeding]W. Kamogawa, H. Matsumoto, Q. Abarr, H. Awaki, R. Bose, D. Braun, G. d. Geronimo, P. Dowkontt, T. Enoto, M. Errando, Y. Fukazawa,
A. Furuzawa, T. Gadson, E. Gau, V. Guarino, S. Gunji, K. Harmon, K. Hayashida, S. Heatwole, F. Imazato, K. Ishibashi, M. Ishida,
N. K. Iyer, F. Kislat, M. Kiss, T. Kitaguchi, H. Krawczynski, J. Lanzi, L. Lisalda, Y. Maeda, H. Matake, T. Mineta, T. Miyazawa,T. Mizuno, T. Okajima, M. Pearce, Z. Peterson, B. Rauch, N. R. Cavero, F. Ryde, T. -A. Stana, D. Stuchlik, G. Simburgeb, S. Spooner,
H. Takahashi, T. Takeda, M. Takeo, T. Tamagawa, H. Tsunemi, N. Uchida, Y. Uchida, K. Uchiyama, A. West, E. A. Wulf, andY. Yoshida, “Optical performance of the X-ray telescope for the XL-Calibur experiment,” Proc. SPIE 12181, 1218171 (2022).

Presentations[International Conferences/Workshops]
T. Tamagawa (invited), “A review of MPGD applications in space missions,” The 7th International Conference on Micro Pattern Gaseous
Detectors (MPGD2022), Rehovot, Israel, December 11–16, 2022.
T. Takeda, T. Tamagawa, T. Enoto, T. Kitaguchi, Y. Kato, T. Mihara, W. Iwakiri, M. Numazawa, Y. Zhou, K. Uchiyama, Y. Yoshida,
N. Ota, S. Hayashi, S. Watanabe, A. Jujo, H. Sato, C. P. Hu, H. Takahashi, H. Odaka, T. Tamba, and K. Taniguchi, “Gas selection for
Xe-based LCP-GEM detectors onboard the CubeSat X-ray observatory NinjaSat,” The 7th International Conference on Micro Pattern
Gaseous Detectors (MPGD2022), Rehovot, Israel, December 11–16, 2022.
N. Ota, T. Tamagawa, T. Enoto, T. Kitaguchi, Y. Kato, T. Mihara, W. Iwakiri, M. Numazawa, Y. Zhou, K. Uchiyama, T. Takeda, Y. Yoshida,
S. Hayashi, S. Watanabe, A. Jujo, H. Sato, C. P. Hu, H. Takahashi, H. Odaka, T. Tamba, and K. Taniguchi, “Development of miniaturizedcircuit boards for GEM detectors onboard the CubeSat X-ray observatory NinjaSat,” The 7th International Conference on Micro Pattern
Gaseous Detectors (MPGD2022), Rehovot, Israel, December 11–16, 2022.

[Domestic Conferences/Workshops]

玉川徹 (招待講演), 「X 線偏光観測—宇宙を見る新しい手段の開拓—」, 日本光学会年次学術講演会, 宇都宮市 (栃木県総合文化センター), 2022 年 11 月 15 日.
玉川徹 (招待講演), 「超小型衛星 NinjaSat プロジェクトと科学教育利用の試み」, 第 14 回小型衛星の科学教育利用を考える会, 調
布市 (成城大学), 2023 年 3 月 17–18 日.
郡司修一, 渡邉瑛里, 寺島政伸, 管佑真, 上小林柾, 玉川徹, 北口貴雄, 榎戸輝揚, 内山慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲, 深沢
泰司, 水野恒史, 高橋弘充, Zhang Sixuan, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell, Paolo Soﬃtt,
Luca Baldini, ほか IXPE 衛星チーム, 「IXPE 衛星による初期科学観測」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大),2022 年 9 月 6–8 日.
水野恒史, 深沢泰司, 高橋弘充, Zhang Sixuan, 郡司修一, 渡邉瑛里, 寺島政伸, 管佑真, 上小林柾, 玉川徹, 北口貴雄, 榎戸輝揚, 内山
慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell, Paolo- 263 -

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Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム, 「IXPE 衛星による「かに星雲・パルサー」の X 線偏光観測」, 日本物理学会 2022
年秋季大会, 岡山市 (岡山理科大), 2022 年 9 月 6–8 日.
渡邉瑛里, 郡司修一, 柴田晋平, 大野寛, 寺島政伸, 管佑真, 上小林柾, 玉川徹, 北口貴雄, 榎戸輝揚, 内山慶祐, 武田朋志, 三石郁之,柏倉一斗, 田原譲, 深沢泰司, 水野恒史, 高橋弘充, Zhang Sixuan, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey,
Stephen O’Dell, Paolo Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム, 「カニ星雲を用いた Chandra と IXPE のジョイント解析による偏光解析手法の開発」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大), 2022 年 9 月 6–8 日.
管佑真, 郡司修一, 渡邉瑛里, 寺島政伸, 上小林柾, 玉川徹, 北口貴雄, 榎戸輝揚, 内山慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲,
深沢泰司, 水野恒史, 高橋弘充, Zhang Sixuan, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell, Paolo
Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム, 「IXPE 衛星を用いたブラックホールスピンの決定方法」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大), 2022 年 9 月 6–8 日.
寺島政伸, 郡司修一, 渡邉瑛里, 管佑真, 上小林柾, 玉川徹, 北口貴雄, 榎戸輝揚, 内山慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲,
深沢泰司, 水野恒史, 高橋弘充, Zhang Sixuan, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell, Paolo
Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム, 「IXPE における増光天体の観測検討とアラートシステムの構築」, 日本物理学会
2022 年秋季大会, 岡山市 (岡山理科大), 2022 年 9 月 6–8 日.
内田悠介, Quin Abarr, 青柳美緒, 朝倉一統, 粟木久光, Matthew G. Baring, Richard Bose, Dana Braun, Gianluigi de Geronimo, Paul
Dowkontt, John Elliot, 榎戸輝揚, Manel Errando, 深沢泰司, 古澤彰浩, Thomas Gadson, Epharaim Gau, Victor Guarino, 郡司修一,
袴田知宏, 萩原涼太, Kenny Hall, 花岡真帆, Keon Harmon, 服部憲吾, 林田清, Scott Heatwole, Arman Hossen, 井出峻太郎, 今村竜太,
今里郁弥, 今澤遼, 石橋和紀, 石田学, 石倉彩美, 石渡幸太, Nirmal Kumar Iyer, Fabian Kislat, Mozsi Kiss, 亀谷紀香, 鴨川航, 北口
貴雄, David Kotsifakis, Henric Krawczynski, James Lanzi, Lindsey Lisalda, 前田良知, 松下友亮, 眞武寛人, 松本浩典, 峯田大晴, 宮本
明日香, 宮澤拓也 R, 水野恒史, 中庭望, 野田博文, 大出優一, 岡島崇, 岡崎貴樹, Izabella Pastrani, Mark Pearce, Zachary Peterson,
Helen Poon, Chris Purdy, Brian Rauch, Felix Ryde, 斎藤芳隆, 佐久間翔太郎, 佐藤淳矢, 澤上拳明, Chris Shreeves, Garry Simburger,
Carl Snow, Sean Spooner, Theodor-Adrian Stana, David Stuchlik, 鈴木瞳, 高橋弘充, 武田朋志, 武尾舞, 玉川徹, 田村啓輔, 常深博,
内田和海, 内山慶祐, Brett Vincent, Andrew West, Eric Wulf, 山本龍哉, 楊冲, 米山友景, 吉田勇登, 善本真梨那, 「硬 X 線偏光観測
気球実験 XL-Calibur の 2022 年スウェーデンフライトの状況報告」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大), 2022
年 9 月 6–8 日.
北口貴雄, 玉川徹, 榎戸輝揚, 加藤陽, 三原建弘, 岩切渉, 沼澤正樹, 周圓輝, 内山慶祐, 武田朋志, 吉田勇登, 大田尚享, 林昇輝, 重城
新大, 渡部蒼汰, 佐藤宏樹, Chin-Ping Hu, 高橋弘充, 小高裕和, 丹波翼, 谷口絢太郎 H 「超小型 X 線衛星 NinjaSat の開発進捗」,日
本物理学会 2022 年秋季大会, 岡山市 (岡山理科大), 2022 年 9 月 6–8 日.
玉川徹, 北口貴雄, 榎戸輝揚, 内山慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲, 郡司修一, 渡邉瑛里, 寺島政伸, 管佑真, 上小林柾,
深沢泰司, 水野恒史, 高橋弘充, Zhang Sixuan, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell, Paolo
Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム, 「X 線偏光観測衛星 IXPE の現状 (2)」, 日本天文学会 2022 年秋季年会, 新潟市 (新潟大), 2022 年 9 月 13–15 日.
高橋弘充, 阪本菜月, 今里郁弥, 山本龍哉, 今澤遼, 眞武寛人, Poon Helen, 楊冲, 水野恒史, 深沢泰司, 内田悠介, 峯田大靖, 鴨川航, 松本
浩典, 服部兼吾, 井出峻太郎, 米山友景, 岡崎貴樹, 朝倉一統, 石倉彩美, 佐久間翔太郎, 花岡真帆, 澤上拳明, 松下友亮, 善本真梨那,
大出優一, 佐藤淳矢, 袴田知宏, 佐藤淳矢, 青柳美緒, 石渡幸太, 萩原涼太, 野田博文, 林田清, 常深博, 前田良知, 石田学, 内田和海,
宮澤拓也, 石橋和紀, 中庭望, 武尾舞, 鈴木瞳, 宮本明日香, 今村竜太, 亀谷紀香, 粟木久光, 古澤彰浩, 北口貴雄, 玉川徹, 榎戸輝揚,
内山慶祐, 武田朋志, 吉田勇登, 郡司修一, 岡島崇, 田村啓輔, Henric Krawczynski, Fabian Kislat, 他 XL-Calibur チーム, 「硬 X 線偏光観測実験 XL-Calibur 気球の 2022 年フライトにおける現地準備状況」, 日本天文学会 2022 年秋季年会, 新潟市 (新潟大), 2022
年 9 月 13–15 日.
大田尚享, 玉川徹, 榎戸輝揚, 北口貴雄, 加藤陽, 三原建弘, 岩切渉, 沼澤正樹, 周圓輝, 内山慶祐, 武田朋志, 吉田勇登, 林昇輝, 重城
新大, 渡部蒼汰, 佐藤宏樹, Chin-Ping Hu, 高橋弘充, 小高裕和, 丹波翼, 谷口絢太郎, 小平聡, 「超小型 X 線衛星 NinjaSat の開発進捗」, 日本天文学会 2022 年秋季年会, 新潟市 (新潟大), 2022 年 9 月 13–15 日.
北口貴雄, 玉川徹, 榎戸輝揚, 加藤陽, 三原建弘, 岩切渉, 沼澤正樹, 周圓輝, 内山慶祐, 武田朋志, 吉田勇登, 大田尚享, 林昇輝, 重城
新大, 渡部蒼汰, 佐藤宏樹, Chin-Ping Hu, 高橋弘充, 小高裕和, 丹波翼, 谷口絢太郎, 「超小型 X 線衛星 NinjaSat に搭載するガス
X 線検出器のオンボード信号処理」, 日本天文学会 2022 年秋季年会, 新潟市 (新潟大), 2022 年 9 月 13–15 日.
林昇輝, 玉川徹, 榎戸輝揚, 北口貴雄, 加藤陽, 三原建弘, 岩切渉, 沼澤正樹, 周圓輝, 内山慶祐, 武田朋志, 吉田勇登, 大田尚享, 重城
新大, 渡部蒼汰, 佐藤宏樹, Chin-Ping Hu, 高橋弘充, 小高裕和, 丹波翼, 谷口絢太郎, 「超小型 X 線衛星 NinjaSat 搭載のガス X 線検出器のエネルギー較正」, 日本天文学会 2022 年秋季年会, 新潟市 (新潟大), 2022 年 9 月 13–15 日.
玉川徹, 北口貴雄, 榎戸輝揚, 内山慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲, 郡司修一, 渡邉瑛里, 寺島政伸, 管佑真, 上小林征,深沢泰司, 水野恒史, 高橋弘充, Sixuan Zhang, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell, Paolo
Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム, 「X 線偏光観測衛星 IXPE ー現状と最新成果」, 宇宙科学シンポジウム 2023, 相模
原市 (JAXA 宇宙科学研究所), 2023 年 1 月 5–6 日.
水野恒史, 玉川徹, 北口貴雄, 榎戸輝揚, 内山慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲, 郡司修一, 渡邉瑛里, 寺島政伸, 管佑真,上小林征, 深沢泰司, 高橋弘充, Sixuan Zhang, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell, Paolo
Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム, 「IXPE 衛星による「かに星雲・パルサー」の X 線偏光観測」, 水野恒史宇宙科学
シンポジウム 2023, 相模原市 (JAXA 宇宙科学研究所), 2023 年 1 月 5–6 日.
寺島政伸, 郡司修一, 渡邉瑛里, 管佑真, 上小林柾, 玉川徹, 北口貴雄, 内山慶祐, 武田朋志, 岩切渉, 三石郁之, 田原譲, 柏倉一斗, 林
田清, 朝倉一統, 榎戸輝揚, 水野恒史, 深沢泰司, 高橋弘充, Zhang Sixuan, Michela Negro, Niccoló Di Lalla, Nicola Omodei, Stefano
Silvestri, Alberto Manfreda, Peter Veres, Eric Burns, Martin Weisskopf, Brian Ramsey, Stephen L. O’Dell, Luca Baldini, ほか IXPE
衛星チーム, 「IXPE 衛星による GRB221009A の観測」
, 宇宙科学シンポジウム 2023, 相模原市 (JAXA 宇宙科学研究所), 2023 年
1 月 5–6 日.
内山慶祐, 玉川徹, 北口貴雄, 榎戸輝揚, 郡司修一, 渡邉瑛里, 寺島政伸, 管佑真, 上小林柾, 水野恒史, 深沢泰司, 高橋弘充, ZhangSixuan,
林田清, 朝倉一統, 三石郁之, 田原譲, 柏倉一斗, 岩切渉, 武田朋志, 「X 線偏光観測衛星 IXPE によるマグネターの偏光観測」, 宇- 264 -

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宙科学シンポジウム 2023, 相模原市 (JAXA 宇宙科学研究所), 2023 年 1 月 5–6 日.
玉川徹, 北口貴雄, 加藤陽, 三原建弘, 榎戸輝揚, 岩切渉, 武田朋志, 吉田勇登, 大田尚享, 林昇輝, 内山慶祐, 渡部蒼太, 重城新大, 周圓輝,
佐藤宏樹, 沼澤正樹, Chin-Ping Hu, 高橋弘充, 小高裕和, 丹波翼, 谷口絢太郎, 「6U X 線天文衛星 NinjaSat」, 超小型衛星利用シンポジウム 2023, 中央区 (X-NIHONBASHI), 2023 年 2 月 21 日.
玉川徹, 北口貴雄 (理研), 榎戸輝揚 (京都大), 内山慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲, 郡司修一, 渡邉瑛里, 寺島政伸, 管佑真,上小林柾, 深沢泰司, 水野恒史, 高橋弘充, Zhang Sixuan, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell,
Paolo Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム, 「X 線偏光観測衛星 IXPE の現状 (3)」, 日本天文学会 2023 年春季年会, 豊島
区 (立教大), 2023 年 3 月 13–16 日.
高橋弘充, 阪本菜月, 今里郁弥, 今澤遼, 眞武寛人, 水野恒史, 深沢泰司, 内田悠介, 峯田大靖, 鴨川航, 倉本春希, 松本浩典, 服部兼吾,
井出峻太郎, 岡崎貴樹, 朝倉一統, 石倉彩美, 佐久間翔太郎, 花岡真帆, 澤上拳明, 松下友亮, 善本真梨那, 大出優一, 佐藤淳矢, 袴田
知宏, 佐藤淳矢, 青柳美緒, 石渡幸太, 萩原涼太, 野田博文, 林田清, 常深博, 前田良知, 石田学, 宮澤拓也, 石橋和紀, 中庭望, 武尾舞,
鈴木瞳, 宮本明日香, 今村竜太, 亀谷紀香, 粟木久光, 古澤彰浩, 北口貴雄, 玉川徹, 榎戸輝揚, 郡司修一, 岡島崇, 田村啓輔, Henric
Krawczynski, Fabian Kislat, 他 XL-Calibur チーム, 「硬 X 線集光偏光計 XL-Calibur 気球実験の 2022 年フライトと今後」, 日本天文学会 2023 年春季年会, 豊島区 (立教大), 2023 年 3 月 13–16 日.
武田朋志, 玉川徹, 榎戸輝揚, 北口貴雄, 加藤陽, 三原建弘, 岩切渉, 沼澤正樹, 内山慶祐, 吉田勇登, 大田尚享, 林昇輝, 重城新大, 渡部
蒼汰, 佐藤宏樹, Chin-Ping Hu, 高橋弘充, 小高裕和, 丹波翼, 谷口絢太郎, 岸本俊二, 「超小型 X 線衛星 NinjaSat の開発進捗 (2)」,
日本天文学会 2023 年春季年会, 豊島区 (立教大), 2023 年 3 月 13–16 日.
榎戸輝揚, 辻直希, 長岡央, 加藤陽, 谷口絢太郎, 大竹淑恵, 若林泰生, 高梨宇宙, 岩本ちひろ, 玉川徹, 晴山慎, 小林泰三, 池永太一, 中野
雄貴, 塚本雄士, 草野広樹, 星野健, 唐牛譲, 上野宗孝, 森本健志, 吉浦伸太郎, 本間希樹, 高橋弘充, 木坂将大, 中澤知洋, 山岡和貴,
仏坂健太, 「MoMoTarO 計画—月面の水資源探査と基礎科学への活用」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3
月 22–25 日.
谷口絢太郎, 榎戸輝揚, 辻直希, 長岡央, 加藤陽, 鶴見美和, 大竹淑恵, 若林泰生, 高梨宇宙, 岩本ちひろ, 玉川徹, 晴山慎, 小林泰三, 池永太一, 中野雄貴, 塚本雄士, 草野広樹, 星野健, 唐牛譲, 上野宗孝, 小松龍世, 「MoMoTarO 計画—月周回軌道を使った中性子寿
命の測定」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
辻直希 , 榎戸輝揚, 長岡央, 加藤陽, 谷口絢太郎, 大竹淑恵, 若林泰生, 高梨宇宙, 岩本ちひろ, 玉川徹, 晴山慎, 小林泰三, 池永太一, 中野雄貴, 塚本雄士, 草野広樹, 星野健, 唐牛譲, 上野宗孝, 「MoMoTarO 計画—中性子とガンマ線の測定を目指す検出器開発」, 日
本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
高橋弘充, Quin Abarr, 青柳美緒, 朝倉一統, 粟木久光, Matthew G. Baring, Richard Bose, Dana Braun, Gianluigi de Geronimo, Paul
Dowkontt, John Elliot, 榎戸輝揚, Manel Errando, 深沢泰司, 古澤彰浩, Thomas Gadson, Epharaim Gau, Victor Guarino, 郡司修一, 袴田知宏, 萩原涼太, Kenny Hall, 花岡真帆, Keon Harmon, 服部憲吾, 林田清, Scott Heatwole, Arman Hossen, 井出峻太郎, 今村竜太,
今里郁弥, 今澤遼, 石橋和紀, 石田学, 石倉彩美, 石渡幸太, Nirmal Kumar Iyer, 亀谷紀香, 鴨川航, Fabian Kislat, Mozsi Kiss, 北口貴雄, David Kotsifakis, Henric Krawczynski, 倉本春希, James Lanzi, Lindsey Lisalda, 前田良知, 松下友亮, 眞武寛人, 松本浩典, 峯田大晴, 宮本明日香, 宮澤拓也, 水野恒史, 中庭望, 野田博文, 大出優一, 岡島崇, 岡崎貴樹, Izabella Pastrani, Mark Pearce, ZacharyPeterson, Chris Purdy, Brian Rauch, Felix Ryde, 斎藤芳隆, 阪本菜月, 佐久間翔太郎, 佐藤淳矢, 澤上拳明, Chris Shreeves, Garry
Simburger, Carl Snow, Sean Spooner, Theodor-Adrian Stana, David Stuchlik, 鈴木瞳, 武尾舞, 玉川徹, 田村啓輔, 常深博, 内田和海,
内田悠介, Brett Vincent, Andrew West, Eric Wulf, 米山友景, 善本真梨那, XL-Calibur チーム, 「硬 X 線集光偏光計 XL-Calibur 気球実験の 2022 年フライトと今後」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
上小林柾, 郡司修一, 渡邉瑛里, 寺島政伸, 管佑真, 玉川徹, 北口貴雄, 榎戸輝揚, 内山慶祐, 武田朋志, 三石郁之, 柏倉一斗, 田原譲,
深沢泰司, 水野恒史, 高橋弘充, Zhang Sixuan, 岩切渉, 林田清, 朝倉一統, Martin Weisskopf, Brian Ramsey, Stephen O’Dell, Paolo
Soﬃtta, Luca Baldini, ほか IXPE 衛星チーム「Crab Pulsar を用いた IXPE 衛星の Encircled Energy Fraction の評価」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
澤野達哉, 米徳大輔, 三原建弘, 有元誠, 鈴木大晴, 吉田翼, 池田博一「X 線突発天体監視速報衛星こようフライトモデル開発報告」,
日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
小高裕和, 市橋正裕, 高嶋聡, 丹波翼, 南木宙斗, 馬場彩, 青山一天, 櫻井真由, 田中雅士, 中曽根太地, 寄田浩平, 一戸悠人, Dmitry
Khangulyan, 井上芳幸, 内田悠介, 須田祐介, 高橋弘充, 深沢泰司, 辻直美, 広島渚, 八幡和志, 米田浩基, 渡辺伸, Tsuguo Aramaki,
Georgia Karagiorgi, Reshmi Mukherjee, GRAMS コラボレーション, 「GRAMS 実験 9: ステータス報告」, 日本物理学会 2023 年
春季大会, オンライン, 2023 年 3 月 22–25 日.
青山一天, 岩澤広大, 櫻井真由, 清水虎冴, 田中雅士, 谷口日奈子, 中島理幾, 中曽根太地, 寄田浩平, 小高裕和, 高嶋聡, 米田浩基,
GRAMS コラボレーション, 「GRAMS-AM 実験 4 大気球搭載液体アルゴン TPC を用いた宇宙反物質探索実験」, 日本物理学会
2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
櫻井真由, 青山一天, 岩澤広大, 清水虎冴, 田中雅士, 谷口日奈子, 中島理幾, 中曽根太地, 寄田浩平, 小高裕和, 高嶋聡, 米田浩基,
GRAMS コラボレーション, 「GRAMS-AM 実験 5 30 × 30 × 30 cm3 液体アルゴン TPC の製作と性能評価」, 日本物理学会 2023
年春季大会, オンライン, 2023 年 3 月 22–25 日.
谷口日奈子, 青山一天, 岩澤広大, 櫻井真由, 清水虎冴, 田中雅士, 中島理幾, 中曽根太地, 寄田浩平, 小高裕和, 高嶋聡, 米田浩基,
GRAMS コラボレーション, 「GRAMS-AM 実験 6 反粒子同定手法検証のための宇宙線ミューオンを用いた地上実験の現状」, 日
本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
中曽根太地, 青山一天, 岩澤広大, 櫻井真由, 清水虎冴, 田中雅士, 谷口日奈子, 中島理幾, 寄田浩平, 小高裕和, 高嶋聡, 米田浩基,
GRAMS コラボレーション, 「GRAMS-AM 実験 7 反粒子同定手法検証のための加速器ビームテスト計画と開発課題」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
米田浩基, 新井翔大, 市橋正裕, 小高裕和, 高嶋聡, 丹波翼, 南木宙斗, 馬場彩, 青山一天, 岩澤広大, 櫻井真由, 清水虎冴, 田中雅士, 谷
口日奈子, 中島理幾, 中曽根太地, 寄田浩平, 一戸悠人, Dmitry Khangulyan, 井上芳幸, 内田悠介, 須田祐介, 高橋弘充, 深沢泰司, 辻直美, 廣島渚, 八幡和志, 渡辺伸, Tsuguo Aramaki, Georgia Karagiorgi, Reshmi Mukherjee, GRAMS コラボレーション, 「GRAMS
実験 10: ステータス報告」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.

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高嶋聡 , 新井翔大, 市橋正裕, 小高裕和, 馬場彩, 青山一天, 櫻井真由, 田中雅士, 中曽根太地, 寄田浩平, 米田浩基, 渡辺伸, GRAMS コ
ラボレーション, 「GRAMS 実験 11: 液体アルゴンコンプトンカメラ実証機の開発状況」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
市橋正裕, 高嶋聡, 新井翔大, 小高裕和, 南木宙斗, 馬場彩, 青山一天, 櫻井真由, 田中雅士, 中曽根太地, 寄田浩平, 米田浩基, 八幡和志, GRAMS コラボレーション, 「GRAMS 実験 12: シンチレーション光検出器系の開発」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
田中雅士, 青山一天, 石川皓貴, 岩澤広大, 内海和伸, 櫻井真由, 清水虎冴, 谷口日奈子, 中島理幾, 中曽根太地, 寄田浩平, 新井翔大,
市橋正裕, 高嶋聡, 馬場彩, 小高裕和, 米田浩基, Tsuguo Aramaki, Georgia Karagiorgi, GRAMS コラボレーション, 「GRAMS-AM
実験 8 大気球搭載液体アルゴン TPC を用いた宇宙反物質探索実験」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月
22–25 日.
櫻井真由, 青山一天, 石川皓貴, 岩澤広大, 内海和伸, 清水虎冴, 田中雅士, 谷口日奈子, 中島理幾, 中曽根太地, 寄田浩平, 新井翔大,
市橋正裕, 高嶋聡, 馬場彩, 小高裕和, 米田浩基, Tsuguo Aramaki, Georgia Karagiorgi, GRAMS コラボレーション, 「GRAMS-AM
実験 9 宇宙線 µ+ /µ− を用いた粒子反粒子識別試験における LArTPC の性能評価」, 日本物理学会 2023 年春季大会, オンライン,
2023 年 3 月 22–25 日.
中曽根太地, 青山一天, 石川皓貴, 岩澤広大, 内海和伸, 櫻井真由, 清水虎冴, 田中雅士, 谷口日奈子, 中島理幾, 寄田浩平, 新井翔大, 市
橋正裕, 高嶋聡, 馬場彩, 小高裕和, 米田浩基, Tsuguo Aramaki, Georgia Karagiorgi, GRAMS コラボレーション, 「GRAMS-AM 実
験 10 J-PARC ハドロンホール K1.8BR における LArTPC を用いた反粒子同定手法検証のための開発状況」, 日本物理学会 2023
年春季大会, オンライン, 2023 年 3 月 22–25 日.

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RIKEN Accel. Prog. Rep. 56 (2023)

Nuclear Science and Transmutation Research Division
Nuclear Many-Body Theory Laborarory
1. Abstract

The nuclear many-body theory laboratory aims to understand various aspects of nuclear structure and reactions due to the assemblyand disassembly of protons and neutrons in the nuclear many-body systems. For this purpose, we construct theoretical models andconduct numerical calculations to describe them. Our research topics include nuclear structure issues such as nuclear deformation,
shell structure, and clustering of unstable nuclei, and nuclear reactions in the Universe where elements originate. In addition to
fundamental research, we are also developing nuclear reaction database by combining the nuclear models and machine learning. The
database will be used for various scientiﬁc and technological applications such as nuclear reactors, medicine and industry.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Structure and reactions of unstable nuclei
Nuclear clustering and related nuclear reactions
Nuclear reactions in the universe
Research and development of the nuclear reaction database for applications

3. Summary of Research Activity(1) Structure and reactions of unstable nuclei
The study of the structure and reactions of unstable nuclei is an important subject of the Nishina Center, as well as one of the core
issues in modern nuclear physics. Our group approaches this problem by performing numerical calculations using theoretical models
such as antisymmetrized molecular dynamics and density functional theory.
The research highlights in this ﬁscal year are as follows: (1) Description of neutron-halo and resonances near and beyond dripline
within the framework of molecular dynamics. We have developed the numerical technique to describe the neutron halos with heavier
masses by the molecular dynamics models. Combining this technique with the method of analytical continuation of the coupling
constant (ACCC), our model can also describe the resonances beyond the neutron dripline. As a benchmark calculation, the method
has been successfully applied to a neutron halo nucleus 31 Ne and an unbound nucleus 25 O. This success opened the way to study
nuclei beyond the drip line in a fully microscopic model. (2) Study of the total reaction cross sections of unstable nuclei. Combining
the microscopic nuclear structure models and a reaction model (Glauber model), we have investigated how the ground-state structureof unstable nuclei aﬀects the reaction cross section. In the study of the oxygen isotopes, the signature of the new shell closure and thegrowth of the neutron skin were found.
(2) Nuclear clustering and related nuclear reactions
The nuclear clustering, in which nucleons are conﬁned into into several subunits (clusters), is an eligible research subject forunderstanding the correlation of nucleons interacting with strong force. Since the clusters are linked to the nuclear reaction channels,
they also appear as the intermediate states of various nuclear reaction dynamics.
The research highlights in this ﬁscal year are as follows: (1) Study of the formation probabilities of α cluster at the surface of
unstable nuclei. Using the antisymmetrized molecular dynamics model, we have investigated how the α cluster formation probability
in unstable Be and C isotopes changes as function of neutron skin thickness. We have demonstrated that the α cluster formation
is hindered by the growth of the neutron skin, which is consistent with the experimental data reported for the Sn isotopes. (2) αcluster formation and total reaction cross section. The formation of α clusters should aﬀect the density proﬁle at the nuclear surface.
Consequently, the signature of the clustering can be observed in the total reaction cross section. We have discussed such eﬀect in thecase of light stable nuclei.
(3) Nuclear reactions in the universe
Fusion reactions that occur in stellar and explosive astronomical events are key to understanding the origin of the elements.
However, many reactions have extremely small cross sections, making direct experimental measurement diﬃcult, and estimating
reaction rates by theoretical calculation is critically important.
In this ﬁscal year, using the antisymmetrized molecular dynamics, we have provided an estimate of the reaction rate of 12 C +12 C
fusion, which is a key reaction for understanding the steller evolution and superburst. We have shown that there are many resonances
within the Gamow window, and hence, the reaction rate at steller temperatures are not hindered but are enhanced in contradiction to
the estimation by a phenomenological model. Using several diﬀerent nuclear density functionals, we have shown how the uncertainityof the nuclear models propages to the raction rate.
(4) Research and development of the nuclear reaction database for applications
Evaluated nuclear data are indispensable in the ﬁeld of nuclear science and technology, and the demand of nuclear data is altering
year by year with technical developments of nuclear science and technology. To meet such demands, an eﬀective and accurate methodthat can regularly generate evaluated nuclear data has been highly desired.
The machine learning technologies can be an answer to this demand, and we are training nuclear reaction models by adopting
the Bayesian optimization (BO) to eﬀectively produce the nuclear data. In this ﬁscal year, we have improved a prototype system
which combines the assembly of the nuclear reaction codes CCONE and BO with Gaussian regression. We have demonstrated that

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RIKEN Accel. Prog. Rep. 56 (2023)

the optical potentials at diﬀerent incident energies can be predicted by using Gaussian Process (GP). Using this method, future RIBF
experimental data can be used to determine optical potentials at arbitrary energies.

Members
Director
Masaaki KIMURA
Contract Researcher
Dang NGUYEN DINH
Visiting Scientists
Wataru HORIUCHI (Osaka Metropolitan Univ.)
Phuc LE (Duy Tan Univ.)
Futoshi MINATO (JAEA)
Takashi NAKATSUKASA (Tsukuba Univ.)
Hung NGUYEN (Duy Tan Univ.)
RHINE KUMAR ARAYAKKANDI KEECH (Cochin Univ. ofSci. and Tech.)
Koichi SATO (Kochi Univ.)
Kazuyuki SEKIZAWA (Tokyo Tech)
Yasutaka TANIGUCHI (NIT, Kagawa College)
Kenichi YOSHIDA (Kyoto Univ.)

Student Trainees
Tatsuhiro HATTORI (Tokyo Tech)
Riku ICHIHASHI (Tokyo Tech)

Shoto WATANABE (Hokkaido Univ.)
Kenta YOSHIMURA (Tokyo Tech)

Visiting Scientists
Kenichi YOSHIDA (Kyoto Univ.)
Kazuyuki SEKIZAWA (TITECH)

Futoshi MINATO (JAEA)
Koichi SATO (Kochi Univ.)

AssistantIzumi YOSHIDA

List of Publications & Presentations
Publications[Original Papers]
Q. Zhao, M. Kimura, B. Zhou, and S. Shin, “α formation probability in 10 Be and 12 Be within a microscopic cluster model,” Phys. Rev. C
106, 054313 (2022).
H. Motoki, Y. Suzuki, T. Kawai, and M. Kimura, “Cluster formation in neutron-rich Be and B isotopes,” Prog. Theor. Exp. Phys. 2022,
113D01 (2022).
T. Baba, Y. Taniguchi, and M. Kimura, “4α linear-chain state produced by 9 Be +9 Be collisions,” Phys. Rev. C 105, L061301 (2022).
H. Masui, W. Horiuchi, and M. Kimura, “Two-Neutron Halo Structure and Anti-halo Eﬀect in 31 F,” Few-Body Syst. 63, 20 (2022).
S. Watanabe, F. Minato, M. Kimura, and N. Iwamoto, “Nuclear data generation by machine learning (I) application to angular distributions
for nucleon-nucleus scattering,” J. Nucl. Sci. and Technol. 59, 1399 (2022).
Y. Suzuki, W. Horiuchi, and M. Kimura, “Erosion of N = 28 shell closure: Shape coexistence and monopole transition,” Prog. Theor.
Exp. Phys. 2022, 063D02 (2022).
J. X. Han et al., “Observation of the π2 σ2 -bond linear-chain molecular structure in 16 C,” Phys. Rev. C 105, 044302 (2022).
Q. Zhao, B. Zhou, M. Kimura, H. Motoki, and S. Shin, “Microscopic calculations of 6 He and 6 Li with real-time evolution method,” Eur.
Phys. J. A 58, 25 (2022).
M. Kimura, Y. Suzuki, T. Baba, and Y. Taniguchi, “Description of isospin mixing by a generator coordinate method,” Phys. Rev. C 105,
014311 (2022).
R. Takatsu, Y. Suzuki, W. Horiuchi, and M. Kimura, “Microscopic study of the deformed neutron halo of 31 Ne,” Phys. Rev. C 107, 024314(2023).
T. Nakatsukasa, “Fermi operator expansion method for nuclei and inhomogeneous matter with a nuclear energy density functional,” Phys.
Rev. C 107, 015802 (2023).
S. Kaur et al., “Proton distribuition radii of 16−24 O: Signatures of new shell closures and neutron skin,” Phys. Rev. Lett. 129, 142502(2022).
H. Tajima, H. Moriya, W. Horiuchi, K. Iida, and E. Nakano, “Resonance-to-bound transition of 5 He in neutron matter and its analogy
with heteronuclear Feshback molecule,” Phys. Rev. C 106, 045807 (2022).
W. Horiuchi and N. Itagaki, “Density proﬁles near nuclear surface of 44, 52 Ti: An indication of α clustering,” Phys. Rev. C 106, 044330(2022).
W. Horiuchi and N. Itagaki, “Imprints of α clustering in the density proﬁles of 12 C and 16 O,” Phys. Rev. C 107, L021304 (2023).
H. Moriya, W. Horiuchi, J. Casal, and L. Fortunato, “Three-α conﬁgurations of the second J π = 2+ state in 12 C,” Eur. Phys. J. A 59, 37(2023).

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RIKEN Accel. Prog. Rep. 56 (2023)

Presentations[International Conferences/Workshops]
M. Kimura (invited) and Y. Taniguchi, “Astrophysical S-factor for 12 C + 12 C fusion reaction from a full-microscopic nuclear model,”Annual Topical Meeting of IReNA - FA1 Nuclear reaction measurements in Underground Laboratories, Online, April 5–8, 2022.
M. Kimura (invited) and Y. Taniguchi, “Low energy monopole strength: A novel approach to the astrophysical fusion reactions,” ECT*Workshop, Advances On Giant Nuclear Monopole Excitations And Applications To Multi-Messenger Astrophysics, Online, July 10–
14, 2022.
M. Kimura (invited), “Monopole transitions as a probe for nuclear shape and clusters,” Developments of Physics of Unstable Nuclei(YKIS2022b), Kyoto, Japan, May 23–27, 2022.
M. Kimura (invited), “Alpha cluster formation at the surface of stable and unstable nuclei,” Korean Physical Society Spring meeting 2022,
Online, April 4–8, 2022.
M. Kimura (invited), “Shape coexistence and electromagnetic moments/transitions,” VI Topical Workshop on Modern Aspects in Nuclear
Structure, Bormio, Italy, February 6–11, 2023.
Y. Taniguchi (invited) and M. Kimura, “Microscopic estimation of 12 C + 12 C fusion reaction rate at astrophysical energies,” YIPQS
long-term workshop Mean-ﬁeld and Cluster Dynamics in Nuclear Systems 2022 (MCD2022), Kyoto, Japan, May 9–June 17, 2022.
F. Minato (invited), “Theoretical studies of beta-decay half-lives,” JSPS/NSFC/NRF A3 Foresight Program Nuclear Physics in the 21stCentury, Osaka, February 13–15, 2023.
F. Minato (invited), “Predictions of beta-decay half-lives and neutron capture cross sections of neutron-rich nuclei,” RIKEN Workshop
Physics of RI; Recent progress and perspectives, Wako, May, 2022.
K. Yoshida (invited), “Mean-ﬁeld based approach for collective excitations in neutron-rich nuclei,” YKIS2022b: Developments of Physics
of Unstable Nuclei, Kyoto, Japan, May 23–27, 2022.
K. Yoshida (invited), “Pairing in neutron-rich nuclei investigated by responses,” Physics of RI: Recent progress and perspectives, Wako,
Japan, May 30–June 1, 2022.
K. Yoshida (invited),“Skyrme-QRPA for monopole modes of excitation,” Advances on Giant Monopole Excitations and Applications toMulti-messenger Astrophysics, ECT*, Trento, Italy & Online, July 11–15, 2022.
K. Sato (invited), “Nuclear density functional calculation with proton-neutron mixing,” YITP Workshop Fundamentals in Density Functional Theory (DFT2022), Kyoto University, December, 2022.
Y. Taniguchi (oral), “12 C + 12 C fusion reaction rate from a microscopic nuclear model,” PANDORA Wrokshop, Onna, Japan, March 5–7,
2023.
Y. Taniguchi (oral), “12 C + 12 C fusion reaction rate from a full-microscopic nuclear model,” The 16th International Symposium on Origin
of Matter and Evolution of Galaxies, Hanoi, Vietnam, October 24–28, 2022.
Y. Taniguchi (oral), “12 C + 12 C fusion astrophysical S-factor from a full-microscopic nuclear model,” Developments of Physics of Unstable
Nuclei (YKIS2022b), Kyoto, Japan, May 23–27, 2022.
F. Minato (oral), “Evaluation of ﬁssion fragment yields and parameter optimization in CCONE code system,” 2nd RCM on Updating
Fission Yield Data for Applications, December, 2022.
F. Minato (oral), “Eﬀects of continuum states on particle emissions from muon captures,” YIPQS long-term workshop on Mean-ﬁeld andCluster Dynamics in Nuclear Systems 2022 (MCD 2022), Kyoto, May, 2022.
F. Minato (oral), “Study of particle emissions following beta-decays and muon captures,” Shapes and Symmetries in Nuclei: from Experiment to Theory (SSNET’22 Conference), Orsay, May, 2022.
K. Sato (oral), “Large-amplitude collective dynamics with the adiabatic SCC theory including the second-order collective operator,”
YIPQS long-term workshop Mean-ﬁeld and Cluster Dynamics in Nuclear Systems 2022 (MCD2022), Yukawa Institute for Theoretical
Physics, Kyoto University, Japan, May 7–June 17, 2022.
S. Watanabe (oral), M. Kimura, F. Minato, S. Yoshida, and N. Iwamoto, “Nuclear data generation by machine learning,” YIPQS long-termworkshop “Mean-ﬁeld and Cluster Dynamics in Nuclear Systems 2022 (MCD2022), Kyoto, Japan, May 9–June 17, 2022.
S. Watanabe, M. Kimura, F. Minato, S. Yoshida, and N. Iwamoto, “Generating nucleon-nucleus scattering data by Gaussian process
regression,” 15th International Conference on Nuclear Data for Science and Technology (ND2022), Online, July 24–29, 2022.

[Domestic Conferences/Workshops]

谷口億宇 (招待講演), 「基底および共鳴状態におけるクラスター相関と天体核反応」, おのころ戸隠夏合宿, JA 長野県ビル, 長野,2022 年 7 月 29, 30 日.
谷口億宇 (招待講演), 木村真明, 「低エネルギー 12 C + 12 C 核融合反応率の微視的模型による評価」, 低エネルギー核物理と高エネ
ルギー天文学で読み解く中性子星, 大阪大学核物理研究センター, 2022 年 8 月 3–5 日.
谷口億宇 (招待講演), 木村真明, 「X 線バーストを引き起こす 12 C + 12 C 分子共鳴状態」, 核反応シミュレーションと機械学習による核反応模型の発展, 北海道大学, 2022 年 12 月 13–15 日.
谷口億宇 (招待講演), 木村真明, 「12 C + 12 C molecular resonances that enhance the fusion reaction rate」, 星の進化と爆発天体における核反応の物理, 理化学研究所, 2023 年 2 月 20–21 日.
谷口億宇 (招待講演), 木村真明, 「天体核融合とノックアウト反応の微視的模型による研究」, 日本物理学会春季大会, オンライン,
2023 年 3 月 22–25 日.
湊太志 (招待講演), 「実験データからの拘束条件下での中性子捕獲断面積の理論予測」, 第 2 回 研究用原子炉を用いた原子核素粒
子物理学（FPUR-II), 2023 年 3 月 16 日.

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湊太志 (招待講演), 「中性子過剰核のベータ崩壊と遅発中性子」, 理化学研究所 RIBF ミニワークショップ「理論と実験で拓く中性
子過剰核の核分裂」, 和光市, 2023 年 2 月 16–17 日.
湊太志 (招待講演), 「様々な拘束条件下での中性子過剰核の捕獲断面積の不定性」, 研究会「中性子捕獲反応で迫る宇宙の元素合成」, 東京, 2023 年 2 月 9–10 日.
湊太志 (招待講演), 「ミュオン捕獲後の粒子放出と半導体ソフトエラー」, 北大情報基盤セ萌芽型共同研究研究会「核反応シミュ
レーションと機械学習による核反応模型の発展」, 札幌, 2022 年 12 月.
湊太志 (招待講演), 「原子核構造モデルによるミュオン捕獲後の粒子放出計算」, ミューオンソフトエラー研究会, 九州大学筑紫キャンパス, 2022 年 11 月.
湊太志 (招待講演), 「Skyrme EDF+QRPA による beta 崩壊半減期の研究」, UKAKUREN-RCNP Conference on AstroNuclear Physics(ANP2022), 豊中, オンライン, 2022 年 7 月.
湊太志 (招待講演), 「中性子過剰核の keV 領域の中性子捕獲反応の理論予測」, RCNP 研究会「研究用原子炉を用いた原子核素粒子物理学」, 茨木, 2022 年 5 月.
谷口億宇 (口頭発表), 木村真明, 「クラスター共鳴による天体における 12 C + 12 C 核融合反応率の増大」, 原子核におけるクラスター
物理の新展開, 大阪公立大学, 2022 年 10 月 19–20 日.
谷口億宇 (口頭発表), 木村真明, 「天体における 12 C + 12 C 核融合反応率の微視的評価」, 日本物理学会 2022 年秋季大会, 岡山理科大学, 2022 年 9 月 6–8 日.
谷口億宇 (口頭発表), 木村真明, 「12 C + 12 C fusion reaction rate at low temperature from a microscopic nuclear model」, UKAKURENRCNP Conference on AstroNuclear Physics (ANP2022), 大阪大学, 2022 年 7 月 20–21 日.
谷口億宇 (口頭発表), 木村真明, 「天体エネルギーにおける 12 C + 12 C 核融合反応率の微視的評価」, RCNP 研究会「原子核反応研
究の最近の話題と展望」, 大阪大学核物理研究センター, 2022 年 7 月 8–9 日.
湊太志 (口頭発表), 「ミュオン捕獲後の粒子放出」, 日本物理学会 2022 年秋季大会, 岡山市, 2022 年 9 月.
堀内渉 (口頭発表), 板垣直之, 「原子核密度分布にみる α クラスター状態」, 大阪公立大研究会「原子核におけるクラスター物理の新展開」, 大阪公立大学杉本キャンパス, 2022 年 10 月 19–20 日.
堀内渉 (口頭発表), 鈴木宜之, M. Shalchi, L. Tomio, 「カルシウム 62, 72 のエキゾチックハロー構造発現の可能性について」, 日本
物理学会 2022 年秋季大会, 岡山理科大学, 2022 年 9 月 6–8 日.
堀内渉 (口頭発表), 稲倉恒法, 「中性子過剰鉛同位体における芯核増大現象」, 日本物理学会 2022 年秋季大会, 岡山理科大学, 2022
年 9 月 6–8 日.
森谷元 (口頭発表), 堀内渉, Jeśus Casal, Lorenzo Fortunato, 「直交条件模型を用いた炭素 12 第二 2+ 状態の研究」, 日本物理学会 2022
年秋季大会, 岡山理科大学, 2022 年 9 月 6–8 日.
槇口雄二 (口頭発表), 堀内渉, 「高エネルギー原子核衝突における不完全吸収反応」, 日本物理学会 2022 年秋季大会, 岡山理科大学,
2022 年 9 月 6–8 日.
堀内渉 (口頭発表), 板垣直之, 「陽子弾性散乱でみる原子核のクラスター構造」, 日本物理学会 2023 年春季大会, オンライン, 2023
年 3 月 22–25 日.
山口雄紀 (口頭発表), 堀内渉, 板垣直之, 「ネオン 20 のクラスター構造と陽子弾性散乱断面積」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
森谷元 (口頭発表), 堀内渉, Bo Zhou, 「パウリ原理を考慮した新しい多クラスター系の基底関数 II」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
吉田賢市 (口頭発表), “Neutron stars tell us the shapes of nuclei,” RCNP 研究会「低エネルギー核物理と高エネルギー天文学で読み解く中性子星」, 大阪大学核物理研究センター, 2022 年 8 月 3–5 日.
吉田賢市 (口頭発表), “Enhanced moments of inertia in neutron-rich nuclei: A role of pair correlations,” 日本物理学会 2022 年秋季大会, 岡山理科大学, 2022 年 9 月 6–8 日.
吉田賢市 (口頭発表), “Collectivity of proton-neutron pairing,” RCNP 研究会「微視的系と巨視的系における核子対凝縮相」, 大阪大学核物理研究センター, 2022 年 9 月 26–28 日.
吉田賢市 (口頭発表), “Linear-response TDDFT for rotating nuclei—Nuclear DFT for rovibrational motions—” Domestic Molecule TypeWorkshop Fundamentals in density functional theory, 京都大学基礎物理学研究所, 2022 年 12 月 7–20 日.
佐藤弘一 (口頭発表), 「高次の集団座標演算子を入れた大振幅集団運動への断熱的アプローチ II」, 日本物理学会 2022 年秋季大会,
岡山理科大学, 2022 年 9 月.
佐藤弘一 (口頭発表), 「ATDHF/ASCC 方程式における解の一意性の破れ」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3月.
渡辺証斗 (口頭発表), 木村真明, 湊太志, 吉田聡太, 岩本信之, 「機械学習を用いた核データ生成」, 日本原子力学会 2022 年秋の年会
大会, 茨城大学, 2022 年 8 月 6–9 日.

[Seminars]

W. Horiuchi, “What can we learn from nuclear density proﬁles ?,” The 311th RIKEN RIBF nuclear physics seminar, RIKEN Nishina
Center (Hybrid), Wako, Japan, November 17, 2022.
吉田賢市, “Shell eﬀects in non-axial-shape excitations,” 第 977 回九大原子核セミナー, 九州大学, 2023 年 1 月 24 日.

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RIKEN Accel. Prog. Rep. 56 (2023)

Nuclear Science and Transmutation Research Division
Superheavy Element Research Group
1. Abstract

The heavy elements with atomic numbers exceeding 103 are called superheavy elements (SHEs). In Superheavy Element Research Group, Superheavy Element Production Team and Superheavy Element Devise Development Team work together to investigate
synthesis of SHEs, nuclear properties of SHE nuclei, and chemical properties of SHEs. We also develop and maintain SHE production
and separation devices, detectors, and chemistry apparatuses.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)
(6)
(7)

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
Development, maintenance, and operation of GARIS, GARIS-II, and GARIS-III
Development and maintenance of detector and DAQ system of GARIS, GARIS-II, and GARIS-III
Development and maintenance of target system of GARIS, GARIS-II, and GARIS-III

3. Summary of Research Activity

See the subsections of Superheavy Element Production Team and Superheavy Element Device Development Team.

MemberDirector
Hiromitsu HABA

List of Publication

Publication
See the subsections of Superheavy Element Production Team and Superheavy Element Device Development Team.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Nuclear Science and Transmutation Research Division
Superheavy Element Research Group
Superheavy Element Production Team
1. Abstract

The elements with atomic number Z ≥ 104 are called as trans-actinide or superheavy elements (SHEs). Superheavy Element
Production Team synthesizes SHE nuclei including new elements and investigates synthesis mechanisms of SHE nuclei, nuclear
properties of SHE nuclei, and chemical properties of SHEs in collaboration with Superheavy Element Devise Development Team andNuclear 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, Z = 113), moscovium (Mc, Z = 115), tennessine (Ts, Z = 117), and oganesson (Og, Z = 118) by International Union of Pureand Applied Chemistry. We have started to search for new elements to expand the chart of the nuclides toward to the island of stability
and the periodic table of the elements toward the 8th period. In January 2020, RIKEN heavy-ion Linear ACcelerator (RILAC) was
upgraded as Superconducting RIKEN heavy-ion Linear ACcelerator (SRILAC). We installed the new gas-ﬁlled recoil ion separator
GARIS-III on the beam line of SRILAC. In June–July 2020, we conducted the commissioning of SRILAC and GARIS-III using the169
Tm + 40 Ar, 208 Pb + 40 Ar, and 208 Pb + 51 V reactions. Since October 2020, we have been conducting a synthesis experiment ofisotopes of new element 119 in the 248 Cm + 51 V reaction under the nSHE collaboration.
(2) Study of reaction mechanisms for production of the heaviest nuclei
SHE nuclei have been produced by complete fusion reactions of two heavy nuclei. However, the reaction mechanism of thefusion process is still not well understood both theoretically and experimentally. In 2022, the quasielastic barrier distribution of the51
V + 248 Cm reaction was extracted by measuring the excitation function of quasielastic backscattering using GARIS-III at SRILAC. The result was utilized to estimate the optimal incident beam energy for production of isotopes of new element 119 in the
248
Cm(51 V, xn)299−x 119 reactions. We also measured the excitation functions for the evaporation residues and the quasielastic scattering of the 51 V + 159 Tb reaction to deepen our understanding of the 51 V-induced reaction on the deformed target.
(3) Study of chemical properties of the heaviest elements
Chemical characterization of newly-discovered SHEs is an extremely interesting and challenging research 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. In 2022, we continued to develop an ultra-rapid gas-chromatograph apparatus, which consists ofan RF carpet gas cell and a cryo-gas-chromatograph column with a Si detector array, at the focal plane of GARIS for the gas chemistryof SHEs. To realize aqueous chemistry studies of Sg (Z = 106) and Bh (Z = 107), we have been developing a continuous andrapid 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. In collaboration with Osaka University, co-precipitation
behavior of No (Z = 102) with BaSO4 and CaC2 O4 was also investigated with 255 No produced in the 248 Cm(12 C, 5n)255 No reaction at
the AVF cyclotron.

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RIKEN Accel. Prog. Rep. 56 (2023)

Members
Team Leader
Hiromitsu HABA
Research & Development Scientist
Daiya KAJI
Visiting Scientists
Marc ASFARI (IPHC/Univ. of Strasbourg)
Mahananda DASGUPTA (Australian Nat’l Univ.)
Olivier DORVAUX (Univ. of Strasbourg)
Benoit Jean-Paul GALL (Univ. of Strasbourg)
Zaiguo GAN (Inst. of Modern Phys./Chinese Academy of Sci.)
David HINDE (Australian Nat’l Univ.)
Minghui HUANG (Inst. of Modern Phys./Chinese Academy ofSci.)
Kieran KESSACI (Univ. of Strasbourg)
Student Trainees
Margaux S.A. FORGE (Univ. of Strasbourg)
Takumi FUKATSU (Kyushu Univ.)
Yuichi ISHIBASHI (Kyushu Univ.)
Sotaro MATSUNAGA (Kyushu Univ.)
Haruki MATSUURA (Kyushu Univ.)

Hiroyuki KOURA (JAEA)
Daisuke NAGAE (Tokyo Tech)
Satoshi SAKAGUCHI (Kyushu Univ.)
Mirei TAKEYAMA (Yamagata Univ.)
Taiki TANAKA (Australian Nat’l Univ.)
Huabin YANG (Inst. of Modern Phys./Chinese Academy ofSci.)
Zhiyuan ZHANG (Inst. of Modern Phys./Chinese Academy ofSci.)
Yuya MICHIMOTO (Kyushu Univ.)
Mikito NOMI (Kyushu Univ.)
Koichi SUGIYAMA (Kyushu Univ.)
Yuki YAMANOUCHI (Kyushu Univ.)

InternMargaux S.A. FORGE (Univ. of Strasbourg)

List of Publications & Presentations
Publications[Original Papers]
A. Yakushev, L. Lens, Ch.E. Düllmann, J. Khuyagbaatar, E. Jäger, J. Krier, J. Runke, H. M. Albers, M. Asai, M. Block, J. Despotopulos,
A. Di Nitto, K. Eberhardt, U. Forsberg, P. Golubev, M. Götz, S. Götz, H. Haba, L. Harkness-Brennan, R.-D. Herzberg, F. P. Heßberger,
D. Hinde, A. Hübner, D. Judson, B. Kindler, Y. Komori, J. Konki, J. V. Kratz, N. Kurz, M. Laatiaoui, S. Lahiri, B. Lommel, M. Maiti,
A. Mistry, Ch. Mokry, K. J. Moody, Y. Nagame, J. P. Omtvedt, P. Papadakis, V. Pershina, D. Rudolph, L. G. Samiento, T. K. Sato,
M. Schädel, P. Scharrer, B. Schausten, D. A. Shaughnessy, J. Steiner, P. Thörle-Pospiech, A. Toyoshima, N. Trautmann, K. Tsukada,J. Uusitalo, K.-O. Voss, A. Ward, M. Wegrzecki, N. Wiehl, E. Williams, and V. Yakusheva, “On the adsorption and reactivity of element
114, ﬂerovium,” Front. Chem. 10, published online (August 25, 2022). DOI: 10.3389/fchem.2022.976635 .
M. Tanaka, P. Brionnet, M. Du, J. Ezold, K. Felker, B. J. P. Gall, S. Go, R. K. Grzywacz, H. Haba, K. Hagino, S. Hogle, S. Ishizawa,D. Kaji, S. Kimura, T. T. King, Y. Komori, R. K. Lemon, M. G. Leonard, K. Morimoto, K. Morita, D. Nagae, N. Naito, T. Niwase,
B. C. Rasco, J. B. Roberto, K. P. Rykaczewski, S. Sakaguchi, H. Sakai, Y. Shigekawa, D. W. Stracener, S. VanCleve, Y. Wang,
K. Washiyama, and T. Yokokita, “Probing optimal reaction energy for synthesis of element 119 from 51 V + 248 Cm reaction withquasielastic barrier distribution measurement,” J. Phys. Soc. Jpn. 91, 084201-1–11 (2022).
A. C. Berriman, D. J. Hinde, D. Y. Jeung, M. Dasgupta, H. Haba, T. Tanaka, K. Banerjee, T. Banerjee, L. T. Bezzina, J. Buete, K. J. Cook,
S. Parker-Steele, C. Sengupta, C. Simenel, E. C. Simpson, M. A. Stoyer, B. M. A. Swinton-Bland, and E. Williams, “Energy dependenceof p + 232 Th ﬁssion mass distributions: Mass-asymmetric standard I and standard II modes, and multichance ﬁssion,” Phys. Rev. C 105,
064614-1–18 (2022).
H. Sakai, H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for superheavy-element research at RIKEN,” Eur. Phys. J. A 58,
238-1–15 (2022).

[Review Article]

羽場宏光, 「人工元素合成」, 科学 92, 846–851 (2022).

[Books]

羽場宏光, 「元素探索と RI 製造」 in 「量子ビーム科学の基礎と応用」, NSA/Commentaries 27, 一般社団法人日本原子力産業協会
原子力システム研究懇話会, 195 ページ, 2023 年 3 月 24 日, p. 26–39.
桜井弘（編）, 荒野泰, 小谷明, 高妻孝光, 佐治英郎, 鈴木晋一郎, 中山祐正, 根矢三郎, 羽場宏光, 廣田俊, 藤井敏司, 「ブルーバックス
元素 118 の新知識 第 2 版」
, 講談社, 2023 年 3 月 20 日, p. 560.

[Proceeding]

H. Sakai, H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for SHE research at RIKEN Nishina Center,” Acta Phys. Pol. B
Proc. Suppl. 16, 4-A10-1–12 (2023).

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RIKEN Accel. Prog. Rep. 56 (2023)

Presentations[International Conferences/Workshops]
H. Haba (invited), “Production and applications of radioisotopes at RIKEN RI Beam Factory—Search for new elements through diagnosis
and therapy of cancer—,” Laser Solutions for Space and the Earth 2022 in OPTICS & PHOTONICS International Congress 2022 (OPIC2022), Yokohama, Japan & Online, April 18–22, 2022.
M. Tanaka (invited) for nSHE Collaboration, “Quasielastic backscattering measurement for 51 V + 248 Cm reaction toward element-119
synthesis at RIKEN,” 19th Workshop on Recoil Separator for Superheavy Element Chemistry & Physics (TASCA 22), Darmstadt,
Germany & Online, May 10–12, 2022.
H. Haba (invited), “Production and applications of radioisotopes at RIKEN RI Beam Factory—Search for new elements through diagnosis
and therapy of cancer—,” IAEA/RCA RTC on Good Manufacturing Practice (GMP) and Radiation Safety Aspects of Radiopharmaceutical Production Using Medical Cyclotron, Online, May16–20, 2022.
H. Sakai (invited), H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for SHE research at RIKEN,” Zakopane Conference on
Nuclear Physics, “Extremes of the Nuclear Landscape,” Zakopane, Poland, August 28–September 4, 2022.
M. Tanaka (oral) for nSHE Collaboration, “Optimal energy for element 119 synthesis via 51 V + 248 Cm reaction probed by quasielastic
barrier distribution measurement,” Zakopane Conference on Nuclear Physics, “Extremes of the nuclear landscape,” Zakopane, Poland,
August 28–September 4, 2022.
S. Sakaguchi (poster) and M. Tanaka for nSHE Collaboration, “Probing optimal energy for synthesis of element 119 from 51 V+248 Cm
reaction,” The 28th International Nuclear Physics Conference (INPC 2022), Cape Town, South Africa, September 11–16, 2022.
A. Takamine (invited), D. Kaji, H. Haba, M. Wada, P. Schury, H. Koura, H. Wollnik, H. Miyatake, H. Ishiyama, K. Morimoto, M. Rosenbusch, S. Kimura, T. Niwase, Y. Hirayama, Y. Ito, Y. Watanabe, and P. Brionnet, “Multi-reﬂection time-of-ﬂight mass spectroscopy ofsuperheavy nuclides,” 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022), Daejeon,
Korea, October 3–7, 2022.
M. Tanaka (oral), “Optimal reaction energy for synthesis of element 119 via 51 V + 248 Cm reaction probed by quasielastic barrier distribution measurement,” 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022), Daejeon,
Korea, October 3–7, 2022.
P. Brionnet (poster), R. Grzywacz, D. Kaji, T. King, T. Niwase, K. Morimoto, and K. Rykaczewski, “Development and optimization of
the digital electronic for the search of new super heavy element at RIKEN on GARIS-III,” 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022), Daejeon, Korea, October 3–7, 2022.
H. Haba (invited), “Production and distribution of radioisotopes at RIKEN RI Beam Factory,” PRISMAP Workshop on Emerging Infrastructures and Technical Developments, Padova, Italy & Online, November 21–22, 2022.
H. Haba (invited), “Production of radioisotopes for application studies at RIKEN RI Beam Factory—Search for new elements throughdiagnosis and therapy of cancer,” The Fifth International Conference on Application of RadiotraCers and Energetic Beams in Sciences(ARCEBS 2023), Purulia, India, January 31–February 5, 2023.

[Domestic Conferences/Workshops]

永井歩夢 (口頭発表), 細川浩由, 中島朗久, 坂口綾, 南部明弘, 重河優大, 羽場宏光, 横山明彦, 「232 Th + 7 Li 核反応によって生成する
U 同位体の ICP-MS による定量」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
渡邉瑛介 (口頭発表), 笠松良崇, 横北卓也, 中西諒平, 大髙咲希, 板倉悠大, 益田遼太郎, 王瑞麟, 重河優大, 南部明弘, 殷小杰, 羽場宏光,
高宮幸一, 篠原厚, 「クラウンエーテルを用いた 102 番元素ノーベリウムの硝酸系固液抽出実験」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
中西諒平 (口頭発表), 渡邉瑛介, 大髙咲希, 王瑞麟, 板倉悠大, 速水翔, 羽場宏光, 南部明弘, 篠原厚, 笠松良崇, 「Rf の共沈実験に向けた Zr, Hf, Th のシュウ酸, マロン酸系でのフロー式共沈実験」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月
15–17 日.
羽場宏光 (依頼講演), 「新元素でがん治療〜理研 RI ビームファクトリーがつくるラジオアイソトープ〜」, 放射線安全フォーラム
第 75 回放射線防護研究会, 「短寿命核種の利用の拡大に向けて」, 文京区 & オンライン, 2022 年 10 月 29 日.
山ノ内邑希 (ポスター発表), 坂口聡志, Pierre Brionnet for nSHE Collaboration, 「新元素合成のための最適反応エネルギー推定に向けた 51 V + 159 Tb 融合反応の励起関数測定」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
深津巧光 (ポスター発表), 坂口聡志, Pierre Brionnet for nSHE Collaboration, 「新元素合成のための最適反応エネルギー推定に向けた 51 V + 159 Tb 融合反応の障壁分布測定 I」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
道本優也 (ポスター発表), 坂口聡志, Pierre Brionnet for nSHE Collaboration, 「新元素合成のための最適反応エネルギー推定に向けた 51 V + 159 Tb 融合反応の障壁分布測定 II」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.

Outreach Activities

羽場宏光 (依頼講演), 「新元素でがん治療—RIBF がつくるラジオアイソトープ—」, 理研と未来を創る会第 28 回講演会, 和光市,
2022 年 9 月 6 日.
羽場宏光 (依頼講演), 「ニホニウム発見への道のり」, 山梨県立吉田高等学校理研見学会, 和光市, 2022 年 11 月 16 日.

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RIKEN Accel. Prog. Rep. 56 (2023)

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 teamis in charge of maintaining, improving, developing, and operating the separators and related devices. In the RIBF facility, three gasﬁlled recoil ion separators are installed at RILAC and RRC facility. One is GARIS that is designed for a symmetric reaction such as
coldfusion reaction, and the other two are developed for an asymmetric reaction such as hot-fusion reaction, GARIS-II and GARIS-III.
New elements 278 113 were produced by 70 Zn + 209 Bi reaction using GARIS. Further the new element search is currently in progressby using GARIS-II and GARIS-III.

2. Major Research Subjects(1) Maintenance of GARIS, GARIS-II and development of new separator GARIS-III(2) Maintenance and development of detector and DAQ system for superheavy element research(3) Maintenance and development of target system for GARIS, GARIS-II and GARIS-III

3. Summary of Research Activity

The GARIS-II and III are newly developed which has an acceptance twice as large as existing GARIS, in order to realize higher
transmission. A new element search program aiming to element 119 was started using GARIS-II. And new separator GARIS-III wasdeveloped and installed into the RILAC experimental hall. After the some commissioning works of GARIS-III, new 119th element
search has been started. We will also oﬀer user-support if a researcher wishes to use the devices for his/her own research program.

Members
Team Leader
Kouji MORIMOTO
Senior Technical Scientists
Masaki FUJIMAKI

Daiya KAJI

Postdoctoral Researchers
Pierre BRIONNET

Sota KIMURA

Visiting Scientists
Shin-ichi GOTO (Niigata Univ.)
Katsuhisa NISHIO (JAEA)
Eiji IDEGUCHI (Osaka Univ.)

Toshitaka NIWASE (KEK)
Yuta ITO (JAEA)
Fuyuki TOKANAI (Yamagata Univ.)

Student Trainee
Kosaku KURAMOTO (Yamagata Univ.)

List of Publications & Presentations
Publications[Original Papers]
P. Brionnet, R. K. Grzywacz, D. Kaji, T. T. King, T. Niwase, K. Morimoto, K. P. Rykaczewski, and H. Sakai, “Development of digitalelectronics for the search of SHE nuclei using GARIS-II/III at RIKEN,” Nucl. Instrum. Methods Phys. Res. A 1049, 168068 (2023).
H. Sakai, H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for superheavy-element research at RIKEN,” Eur. Phys. J. A 58,
238 (2022).
M. Tanaka, P. Brionnet, M. Du, J. Ezold, K. Felker, B. J. P. Gall, S. Go, R. K. Grzywacz, H. Haba, K. Hagino, S. Hogle, S. Ishizawa,D. Kaji, S. Kimura, T. T. King, Y. Komori, R. K. Lemon, M. G. Leonard, K. Morimoto, K. Morita, D. Nagae, N. Naito, T. Niwase,
B. C. Rasco, J. B. Roberto, K. P. Rykaczewski, S. Sakaguchi, H. Sakai, Y. Shigekawa, D. W. Stracener, S. VanCleve, Y. Wang,
K. Washiyama, and T. Yokokita, “Probing optimal reaction energy for synthesis of element 119 from 51 V + 248 Cm reaction withquasielastic barrier distribution measurement,” J. Phys. Soc. Jpn. 91, 084201 (2022).
T. Niwase, Y. X. Watanabe, Y. Hirayama, M. Mukai, P. Schury, A. N. Andreyev, T. Hashimoto, S. Iimura, H. Ishiyama, Y. Ito, S. C. Jeong,
D. Kaji, S. Kimura, H. Miyatake, K. Morimoto, J. -Y. Moon, M. Oyaizu, M. Rosenbusch, A. Taniguchi, and M. Wada, “Discovery of
new isotope 241 U and systematic high-precision atomic mass measurements of neutron-rich Pa-Pu nuclei produced via multinucleon
transfer reactions,” Phys. Rev. Lett. 130, 132502 (2023).
T. Niwase, W. Xian, M. Wada, M. Rosenbusch, S. Chen, A. Takamine, J. Liu, S. Iimura, D. Hou, S. Yan, H. Ishiyama, H. Miyatake,S. Nishimura, D. Kaji, K. Morimoto, Y. Hirayama, Y. X Watanabe, S. Kimura, P. Schury, and H. Wollnik, “Development of a β-TOF
detector: An enhancement of the α-TOF detector for use with β-decaying nuclides,” Prog. Theor. Exp. Phys. 2023, 031H01 (2023).
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RIKEN Accel. Prog. Rep. 56 (2023)

M. Rosenbusch, M. Wada, S. Chen, A. Takamine, S. Iimura, D. Hou, W. Xian, S. Yan, P. Schury, Y. Hirayama, Y. Ito, H. Ishiyama,
S. Kimura, T. Kojima, J. Lee, J. Liu, S. Michimasa, H. Miyatake, M. Mukai, J. Y. Moon, S. Nishimura, S. Naimi, T. Niwase, T. Sonoda,
Y. X. Watanabe, and H. Wollnik, “The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN’s RIBF
facility,” Nucl. Instrum. Methods Phys. Res. A 1047, 167824 (2023).
S. Iimura, M. Rosenbusch, A. Takamine, Y. Tsunoda, M. Wada, S. Chen, D. S. Hou, W. Xian, H. Ishiyama, S. Yan, P. Schury, H. Crawford,
P. Doornenbal, Y. Hirayama, Y. Ito, S. Kimura, T. Koiwai, T. M. Kojima, H. Koura, J. Lee, J. Liu, S. Michimasa, H. Miyatake,J. Y. Moon, S. Naimi, S. Nishimura, T. Niwase, A. Odahara, T. Otsuka, S. Paschalis, M. Petri, N. Shimizu, T. Sonoda, D. Suzuki,
Y. X. Watanabe, K. Wimmer, and H. Wollnik, “Study of the N = 32 and N = 34 shell gap for Ti and V by the ﬁrst high-precisionmultireﬂection time-of-ﬂight mass measurements at BigRIPS-SLOWRI,” Phys. Rev. Lett. 130, 012501 (2023).

[Proceeding]
H. Sakai, H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for SHE research at RIKEN Nishina Center,” Acta Phys. Pol. B
Proc. Suppl. 16, 4-A10-1–12 (2023).

Presentations[International Conferences/Workshops]
H. Sakai (invited), “Facility upgrade for SHE research at RIKEN Nishina Center,” 57th Zakopane Conference on Nuclear Physics, Zakopane, Poland, August 28–September 4, 2022.
K. Morimoto (oral), “Present status and plans of GARIS-II and GARIS-III,” SSRI-PNS Collaboration Meeting 2022, Wako, Saitama &Online, September 1, 2022.
S. Kimura (oral), “Study of the neutron-rich 252 Cf-ﬁssion-fragments with MRTOF-MS,” The 16th International Symposium on Origin of
Matter and Evolution of Galaxies (OMEG16), Hanoi, Vietnam, October 24–28, 2022.
M. Tanaka (poster) and S. Sakaguchi for nSHE Collaboration, “Probing optimal energy for synthesis of element 119 from 51 V + 248 Cm
reaction,” The 28th International Nuclear Physics Conference (INPC 2022), South Africa, September 11–16, 2022.
P. Brionnet (invited), “Upgrade of the detection setup of the gas-ﬁlled recoil separator GARIS-III,” 19th TASCA22 Workshop, GSI
Darmstadt, Germany & Online, May 10–12, 2022.
P. Brionnet (poster), “Development and optimization of the digital electronic for the search of new super heavy element at RIKEN on
GARIS-III,” 19th International Conference on Electromagnetic Isotope Separators and Related Topics, EMIS 2022, Daejeon, South
Korea, October 3–7, 2022.

[Seminar]
H. Sakai, “Facility upgrade for SHE research at RIKEN Nishina Center,” C2R2 Seminer, IBS CENS, September 29, 2022.

[Domestic Conferences/Workshops]

倉本幸作 (ポスター発表), 森本幸司, 加治大哉, 武山美麗, 門叶冬樹, 「超重核実験用ピクセル型大面積半導体検出器の性能評価」,
第 37 回 研究会「放射線検出器とその応用」, 茨城県つくば市 (高エネルギー加速器研究機構放射線科学センター), 2023 年 1 月
25–27 日.
倉本幸作 (ポスター発表), 森本幸司, 加治大哉, 武山美麗, 門叶冬樹, 「超重核実験用ピクセル型大面積半導体検出器の性能評価」, 第83 回応用物理学会秋季学術講演会, 東北大学川内北キャンパス & オンライン, 2022 年 9 月 20–23 日.
倉本幸作 (口頭発表), 森本幸司, 加治大哉, 武山美麗, 門叶冬樹, 「超重核実験用ピクセル型半導体検出器の不感層評価」, 第 59 回 ア
イソトープ・放射線研究発表会, オンライン, 2022 年 7 月 6–8 日.

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RIKEN Accel. Prog. Rep. 56 (2023)

Nuclear Science and Transmutation Research Division
Astro-Glaciology Research Group
1. Abstract

Our Astro-Glaciology Laboratory promotes both experimental and theoretical studies to open up the new interdisciplinary researchﬁeld of astro-glaciology, which combines astrophysics, astrochemistry, glaciology, and climate science.
On the experimental side, we measure isotopic and ionic concentrations in ice cores drilled at Dome Fuji station, Antarctica,
in collaboration with the National Institute of Polar Research (NIPR, Tokyo). Here, the ice cores are time capsules which preserve
atmospheric information of the past. In particular, the ice cores obtained around the Dome Fuji site are very unique, because they
contain much more information on the stratosphere than any other ice cores obtained from elsewhere on Earth. This means that wehave signiﬁcant advantages in using Dome Fuji ice cores if we wish to study the Universe, since UV photons, gamma-rays, and highenergy protons emitted by astronomical phenomena aﬀect the stratosphere.
Our principal aim is thus to acquire and interpret information preserved in ice cores regarding:• Signatures of past volcanic eruptions and solar cycles;• Relationship between climate change and solar activity;• Traces of past supernovae in our galaxy, in order to understand better the rate of galactic supernova explosions.
Moreover, we are promoting experimental projects on:• Development of an automated laser melting sampler for analyzing ice cores with high depth resolution;• Development of precise analytical techniques of high sensitivity for analyzing ice cores;• The application of analytical methods for measuring isotopes in ice cores to archaeological artifacts;• The evolution of molecules in space;On the theoretical side, we are simulating numerically:• Chemical eﬀects of giant solar ﬂares and supernovae on the Earth’s atmosphere;• The explosive and the r-process nucleosynthesis in core-collapse supernovae;
Combining our experimental evidence and theoretical simulations, we are promoting the researches mentioned above. These all willcontribute to understanding relationships between the Universe and Earth. In particular, climate change is the most critical issue facing
the world in the 21st century. It is also emphasized that the frequency of supernova explosions in our galaxy has not yet been fully
understood, and it is the key to understand the r-process nucleosynthesis.

Members
Director
Yuko MOTIZUKI
Senior Research Scientist
Yoichi NAKAI
Special Temporary Research Scientist
Kazuya TAKAHASHITechnical Staﬀ
Yu Vin SAHOO
Senior Visiting Scientists
Yasushige YANO (Nishina Memorial Foundation)
Hideharu AKIYOSHI (National Institute for Environmental
Studies)

Kunihiko KODERA (Meteorological Res. Inst.)

Visiting Scientists
Hisashi HAYAKAWA (Nagoya Univ.)
Hideki MADOKORO (Mitsubushi Heavy Industries, Ltd.)

Kazuho HORIUCHI (Hirosaki Univ.)
Akira HORI (Kitami Inst. of Tech.)

Visiting Technicians
Junya HIROSE (Fusion Tech. Co., Ltd.)

Yuma HASEBE (Denryoku Comp. Ctr., Ltd.)

Research Part-time Worker
Kazuhito ITO- 277 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Administrative Part-time Worker
Kanako FUJITA
Assistant
Asako SAKIHAMA

List of Publications & Presentations
Publications[Original Papers]
S. Katsuda, T. Enoto, A. N. Lommen, K. Mori, Y. Motizuki, M. Nakajima, N. C. Ruhl, K. Sato, G. Stober, M. S. Tashiro, Y. Terada,
and K. S. Wood, “Long-term density trend in the mesosphere and lower thermosphere from occultations of the crab nebula with X-ray
astronomy satellites,” J. Geophys. Res. Space Phys. 128, e2022JA030797 (2023).
A. Miyazaki, M. Tsuge, H. Hidaka, Y. Nakai, and N. Watanabe, “Direct determination of the activation energy for diﬀusion of OH radicals
on water ice,” Astrophys. J. Lett. 940, L2 (2022).
Y. Miyake, N. Ikoma, K. Takahashi, Y. V. Sahoo, and H. Okuno, “Test of 107 Pd transmutation with macroscopic quantities,” J. Nucl. Sci.
Technol. 59, 1536 (2022).
K. Takahashi, Y. V. Sahoo, Y. Nakai, H. Motoyama, and Y. Motizuki, “Annually resolved proﬁles of δ34 S and sulfate in shallow ice core
DF01 (Dome Fuji, Antarctica) spanning the nineteenth century and their geochemical implications,” J. Geophys. Res. Atmos. 127,e2021JD036137 (2022).

Presentations[International Conferences/Workshops]
Y. Motizuki (invited), “Verifying footprints of solar cycles and supernovae in polar ice cores,” International Conference on Astrophysics
with Radioactive Isotopes (AwRI), Budapest & Online, June 12–17, 2022.
S. Katsuda (poster), T. Enoto, A. N. Lommen, K. Mori, Y. Motizuki, M. Nakajima, N. C. Ruhl, K. Sato, G. Stober, M. S. Tashiro,
Y. Terada, and K. S. Wood, “Measuring vertical density proﬁles of Earth’s upper atmosphere using X-ray astronomy satellites,” AGU
Fall Meeting 2022, Chicago & Online, December 12–16, 2022.
Y. Motizuki (poster), Y. Nakai, K. Takahashi, T. Imamura, and H. Motoyama, “Eleven-year, 22-year and ∼90-year solar cycles discoveredin nitrate concentrations in a Dome Fuji (Antarctica) ice core,” The 5th ISEE International Symposium: Toward the Future of SpaceEarth Environmental Research, Nagoya & Online, November 15–17, 2022.

[Domestic Conferences/Workshops]

望月優子 (招待講演), 「地質学的試料に残った超新星の痕跡について」, 新学術領域「地下から解き明かす宇宙の歴史と物質の進化」主催第 9 回超新星ニュートリノ研究会, 九州大学・伊都キャンパス & オンライン, 2023 年 3 月 2–3 日.
望月優子 (招待講演), 「南極アイスコアから探る太陽活動と気候変動〜太陽の鼓動—星と私たちの繋がりを通して」, お茶の水女子大学理学部主催第 10 回宇宙講演会, 東京, 2022 年 12 月 10 日.
望月優子 (招待講演), 「南極の氷からひもとく地球と宇宙の歴史」, 朝日カルチャーセンター新宿教室, オンライン, 2022 年 8 月
27 日.
望月優子 (招待講演), 「Solar activity signatures embedded in ice cores」, 宇核連—RCNP 研究会「宇宙核物理の展開」, 豊中 & オンラ
イン, 2022 年 7 月 20–21 日.
中井陽一, 渡部直樹, 柘植雅士, 副島浩一, 「極低温氷表面に存在する OH ラジカルの可視域光による光脱離」, 日本物理学会 2023
年春季大会, オンライン, 2023 年 3 月 22–25 日.
中井陽一, 「低エネルギーイオンと極低温氷表面との分子生成反応」, 学術変革領域次世代アストロケミストリー第 3 回領域全体
集会, 東京, 2023 年 3 月 7–9 日.
勝田哲, 榎戸輝揚, L. Andrea, 森浩二, 望月優子, 中島基樹, R. Nathaniel, 佐藤浩介, S. Gunter, 田代信, 寺田幸功, W. Kent, 「Ｘ線天文衛星を用いた地球超高層大気の密度鉛直構造の測定〜長期トレンドの調査〜」, 地球電磁気・地球惑星圏学会 第 152 回総会及び講演会 (2022 年秋学会), 相模原, 2022 年 11 月 3–7 日.

Press Releases

勝田哲, 榎戸輝揚, L. Andrea, 森浩二, 望月優子, 中島基樹, R. Nathaniel, 佐藤浩介, S. Gunter, 田代信, 寺田幸功, W. Kent, 「地球温暖化に伴う超高層大気の収縮を X 線天文衛星で解明」, 2023 年 2 月 2 日, https://www.riken.jp/press/2023/20230222_2/ .
宮崎彩音, 柘植雅士, 日髙宏, 中井陽一, 渡部直樹, 「極低温氷表面での OH ラジカルの動きやすさを初めて測定—宇宙の氷微粒子
上で分子進化が活性化する温度が明らかに—」, 2022 年 11 月 24 日, https://www.riken.jp/press/2022/20221124_1/ .

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RIKEN Accel. Prog. Rep. 56 (2023)

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 ﬁnd
out 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. In November 2020, Hideaki Otsu organized a domestic conference entitled “RIKEN Sympoium on Nuclear Data
2020.”At the end of ﬁscal year 2021, the spallation reaction data with 99 Tc beam was obtained and a secondary beam test for 237 Np
production was conducted. The data analysis is in progress.

MemberDirector
Hiroyoshi SAKURAI

List of Presentation
Presentation[Domestic Conference/Workshop]

櫻井博儀（招待講演）, 「核変換とミュオン」, 日本中間子科学会「中間子科学の将来討論会」, 和光市 (理化学研究所), 2022 年 11 月.

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RIKEN Accel. Prog. Rep. 56 (2023)

Nuclear Science and Transmutation Research Division
Nuclear Transmutation Data Research Group
Fast RI Data Team
1. Abstract

Fast RI data team aims at obtaining and accumulating the cross section data for long lived ﬁssion products (LLFPs) in order toexplore the possibility of using accelerator for nuclear transmutation.
LLFPs as nuclear waste have been generated continuously in nuclear power plants for wealth for human lives, while people
noticed the way of disposal has not necessarily been established, especially after the Fukushima Daiichi power plant disaster. One of
the ways to reduce the amount of LLFP or to recover them as recycled resources is nuclear transmutation technique.
RIBF facility has a property to generate such LLFP as a secondary beam and the beam species are identiﬁed by event by event.
Utilizing the property, absolute values of the cross section of various reactions on LLFPs are measured and accumulated as a database.
In addition, a project to obtain nuclear reaction data on stable nuclei by means of inverse kinematic technique to provide the
distribution of reaction residue nuclides. It will be utilized on Pb/Bi for ADS neutron generator materials or on Li/Be for blanket on
nuclear fusion reactors.
Furthermore, we started to obtain production cross section to minor actinide (MA) nuclide from primary uranium beam. Thismethods will provide an opportunity to study MA nuclides by distributing them as a secondary beam in near future.

2. Major Research Subjects(1) Measurement of reaction products by the interaction of LLFPs with proton, deuteron, and photon to explore candidate reactions for the transmutation of LLFPs(2) Evaluation of the cross section data for the neutron induced reactions from the obtained data

3. Summary of Research Activity
(1)
(2)
(3)
(4)

Acting as a collaboration hub on many groups which plan to take data using fast RI beams in RIBF facility
Concentrating on taking data for proton and deuteron induced spallation reactions with inverse kinematics
Accumulating the cross section data and evaluating them as evaluated nuclear data
Evaluating cross section of neutron induced reaction on LLFP by collaborating with the nuclear model calculation and evaluation group

Members
Team Leader
Hideaki OTSU (Concurrent: Team Leader, SAMURAI Team)
Junior Research Associate
Riku MATSUMURA
Visiting Scientists
Takashi TERANISHI (Kyushu Univ.)
Ayano MAKINAGA (Teikyo Univ.)

Shin’ichiro MEIGO (JAEA)
Keita NAKANO (JAEA)

List of Publications & Presentations
Presentations[Domestic Conferences/Workshops]
R. Matsumura, “New analytical model for momentum distribution on the spallation reaction in inverse kinematics,” 2022 Symposium on
Nuclear Data, Kinki University, Osaka, Japan, November 17–18, 2022.
R. Matsumura, “New analytical model for momentum distribution on the spallation reaction in inverse kinematics,” JSPS/NRF/NSFC
A3 Foresight Program, “Nuclear Physics in the 21st Century,” Osaka International Convention Center, Osaka, Japan, February 13–15,
2023.

Other
[Bachlar Thesis]

福嶋千隼, 卒業論文, 「理研 RI ビームファクトリーでのネプツニウム 237 同位体の生成」, 東京都市大学, 2023 年 3 月.

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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) or minor actinides(MA) from the 238 U by means of 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) 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.
(3) Development of MA (such as Np) beams for the nuclear data
(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 in 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 in October 2016. The commissioning experiment of the OEDO beam line
was successfully performed in 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. To easily produce the slowed-down RI beam, the framework,
called BYACO, is being developed to seamlessly handle the device, detector, DAQ, and analysis. The procedure of the RI-beam energy
control was implemented in the web application. The BYACO system was used also for an RI-beam automatic tuning project by the
BigRIPS team. The automatic tuning of the RI beam becomes one of the categories in the RNC’s use case of the TRIP project.
BYACO needs to be upgraded when the automatic tuning is used under the operation. Future developments were considered in 2022.
The extension of the RI-beam separation using the Bρ-∆E-Bρ method by the charge state of RI beam was found to be essential toproduce the heavy RI beams. The simulation tool of this extended separation, called Q+ separation, was developed and implemented
into BYACO in 2021. With this tool, we succeeded to produce a 237 Np beam as a secondary beam by collaborating mainly with thefast RI data team and the BigRIPS team.

Members
Team Leader
Toshiyuki SUMIKAMA
Visiting Scientist
SungHan BAE (Inst. for Basic Sci.)
Student Trainee
Masaya OISHI (Kyushu Univ.)

List of Presentation
Presentation[Domestic Conference/Workshop]

炭竃聡之（招待講演）, 「理研・低速 RI データチームから」, 原子核物理学実験におけるデータ利活用による研究戦略, オンライン,
2022 年 3 月 7 日.

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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
to form a muonic atom and cascades down to the 1s 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
A−x
N (x = 0, 1, 2, 3, 4) by emitting some neutrons in the reaction. The phenomenon isand mass number A generates the isotopes of Z−1
A−x
N reactions (x = 0, 1, 2, 3, 4) is one of importantcalled “muon nuclear transmutation.” The reaction branching ratio of ZA N(µ− , xnν)Z−1
factors 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
A−x
N nuclei are prompt events and are observed by the “muonmethod.” The neutron and γ-ray emissions from the excited states of Z−1
in-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
A−x
N make β+/− decays. The γ-rays associated with β+/− decays to the daughter nuclei aremuon beam. The produced unstable nuclei Z−1
observed 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
A−x
N nuclei are determined
the half-lives and decay branching ratios of β+/− -γ decays are known, the reaction branching ratios to the Z−1
by 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−x
Rh reactions, wheremuon beam arrival. The measured neutron multiplicity gives the reaction branching ratio of 46A Pd(µ− , xnν)45
A = 104, 105, 106, 108, 110 and x = 0, 1, 2, 3, 4.
Employing a newly built neutron spectrometer, the neutron was measured to obtain the reaction branching ratios of muon capture
reactions on the Pd targets. We have constructed a neutron spectrometer named “Seamine”: Scintillator Enclosure Array for Muon
Induced Neutron Emission. The spectrometer consists of 21 liquid scintillation counters, 2 Ge γ-ray detectors, 7 BaF2 counters. The
Pd target, muon beam counters and muon degraders are placed at the center of spectrometer. The neutron counter is a BC-501A
liquid scintillation counter with 20 cm diameter and 5 cm depth and is connected to a 5” photo multiplication tube (H4144-01). The
total neuron detection eﬃciency is estimated 5%, where the distance is 4 cm from the target to neutron counters. The Ge γ-ray
detectors are placed at 10 cm form the target, and the typical detection eﬃciency is 0.5% for 200 keV γ-ray. The BaF2 counters arelocated beneath the target to detect fast γ-rays emitted from the compound nucleus formed in the reactions. Signals from the liquid
scintillation counters are processed in a CAEN V1730B waveform digitizer (16 channel, 14 bit, 500 M samplings/sec.). The neuron-γ
discrimination is performed on-line during the experiment, and the detailed data analysis is conducted oﬀ-line after the experiment.
The neutron energy spectrum is constructed in the digitizer. Signals from Ge detectors are also processed in the digitizer to obtain theenergy and time spectrum of γ-rays associated with the reaction. Signals from the BaF2 counters and muon beam counters are sent to
the digitizer to make the fast timing signals.
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is in progress to obtain the multiplicity, the energy and the TOF spectrum using start signals given by γ-rays detected in the BaF2
counters. The γ-ray data gives the energy spectrum of prompt γ-rays and muonic X-rays originated from the 104, 105, 106, 108, 110 Pdtargets.
(2) Experiments with “muon activation method” at the RIKEN-RAL Muon Facility
We conducted the experiments on the muon nuclear capture employing the muon activation method at the RIKEN-RAL Muon
Facility in the UK. The pulsed muon beam was irradiated on the 104, 105, 106, 108, 110 Pd targets. The γ-rays were detected by a Ge detector
located at the downstream of the Pd targets to maximize the detection eﬃciency. The build-up and decay curves of γ-ray intensities
were measured associated with β+/− decays of produced unstable nuclei to daughter nuclei. The γ-ray-yield curves give the absolute
A−x
Rh reactions. The
radiation activity produced by the reaction, and the reaction branching ratios are determined for 46A Pd(µ− , xnν)45
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−x
Y reactions, where A = 90, 91, 92, 94, 96. The obtained reaction branching ratios on thereaction branching ratios of 40A Zr(µ− , xnν)39
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−x
Rh reactions, the muon activation experiment was performed
In order to obtain the reaction branching ratio of 107
46 Pd(µ , xnν)45
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−x
Rh reactions is ﬁnally determined. The detailed oﬀ-line data analysis is in progress.
ratio of 107
46 Pd(µ , xnν)45(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
Megumi NIIKURA
Senior Visiting Scientist
Teiichiro MATSUZAKI

List of Publications & Presentations
Publications[Original Papers]
T. Nishi et al., “Chiral symmetry restoration at high matter density observed in pionic atoms,” Nat. Phys. 19, 788 (2023).
A. Yagi et al., “Various nuclear structures in 140 Xe studied by beta decay of ground and isomeric states in 140 I,” Phys. Rev. C 105, 044325(2022).
B. Moon et al., “First observation of the π0h(11/2) × ν0h(9/2) partner orbital conﬁguration in the odd-odd 138 I nucleus,” Phys. Rev. C 105,
034334 (2022).
B. Moon et al., “Gamow-Teller decay of 142 Te to 142 I,” Phys. Rev. C 107, 014311 (2023).

[Proceeding]
S. Manabe et al., “Emissions of hydrogen isotopes from the nuclear muon capture reaction in nat Si,” EPJ Web Conf. 284, 01029 (2023).

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Presentations[International Conferences/Workshops]
M. Niikura (oral), “Nuclear physics with muon,” Physics of RI: Recent progress an dperspective, RIKEN, Wako, May, 2022.
M. Niikura (oral), “Study of muon-induced ﬁssion for spectroscopy of the muonic atom with unstable nuclei,” Open CHRISP Users
Meeting, PSI, Villigen, Switzerland, January, 2023.
R. Mizuno et al. (poster), “Measurement of muon-induced nuclear transmutation for Si isotopes,” Transscale Quantum Science, Univ. ofTokyo, November, 2022.
R. Mizuno et al. (oral), “Measurement of nuclear transmutation via muon capture reaction for Si isotopes,” VIth Topical Workshop on
Modern Aspects in Nuclear Structure, Bormio, Italy, February, 2023.

[Domestic Conferences/Workshops]

新倉潤 (口頭発表), “Study of muon-induced ﬁssion for spectroscopy of the muonic atom with unstable nuclei,” Fission Workshop, 和光
市 (理科学研究所), 2023 年 1 月.
新倉潤 (招待講演), 「ミューオン原子核物理」, 中間子科学の将来検討会, 和光市 (理化学研究所), 2022 年 11 月.
水野るり惠, 他 7 名 (口頭発表), 「1 MeV 陽子ビームを用いた広ダイナミックレンジ光子検出器の性能評価実験」, タンデム加速器
及びその周辺技術の研究会, オンライン, 2022 年 7 月.
水野るり惠, 他 7 名 (口頭発表), 「Ge 検出器を用いた光子検出器システムの広ダイナミックレンジにおける性能評価実験」, 放射
線化学討論会, オンライン, 2022 年 9 月.

[Seminar]

M. Niikura, “Development of muonic X-ray spectrometer for element analysis,” LMU seminar at Paul Scherrer Institut (PSI), Online,
April, 2022.

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Nuclear Science and Transmutation Research Division
High-Intensity Accelerator R&D Group
1. Abstract

The High-Intensity Accelerator R&D group, consisting of two teams, develops elemental technology of high-power acceleratorsand high-power targets, aiming at future applications to nuclear transmutations of long-lived ﬁssion product into short-lived nuclides.
The research subjects are superconducting rf cavities for low-velocity ions, design of high-power accelerators, high-power target
systems and related technologies.
Nuclear transmutation with high-intensity accelerators is expected to reduce the high-level radioactive wastes and to recycle
the precious resources such as rare-earth materials in future. This method is one of the important applications of the ion-accelerator
technologies that have been developed at RIKEN for a long time. Under the framework of ImPACT Fujita Program, we have conducted
R&D of elemental technology related to the high-power accelerators and high-power targets, from FY2014 to FY2018. We gained alot of experiences in these R&Ds. Among them, the development of a superconducting rf cavity has become the basis of the upgrade
program of the RILAC facility which started in 2016.

2. Major Research Subject

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.

Members
Director
Hiroki OKUNO(concurrent: Deptuy Group Director, Accelerator Group)
Visiting Scientist
Hideyuki Watanabe (AIST)- 285 -

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Nuclear Science and Transmutation Research Division
High-Intensity Accelerator R&D Group
High-Gradient Cavity R&D Team
1. Abstract

Superconducting linacs are suitable for high-power beam facilities, such as spallation neutron sources. The mission of this teamis to develop a highly eﬃcient superconducting linac with a high acceleration voltage, capable of handling high beam intensity andensuring high availability, drawing from the operational experiences of SRILAC.

2. Major Research Subjects(1) Development of high-gradient cavites for low beta ions
(2) Development of power saving cryomodules(3) Operation wigh high availability

3. Summary of Research Activity

Development of highly eﬃcient superconducting accelerator modules

Members
Team Leader
Naruhiko SAKAMOTO
Research/Technical Scientists
Yutaka WATANABE

Kazutaka OZEKI

Research & Development Scientist
Kenji SUDA

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Nuclear Science and Transmutation Research Division
High-Intensity Accelerator R&D Group
High-Power Target R&D Team
1. Abstract

The subjects of this team cover R&D studies with respect to target technology for the transmutation of the LLFPs.

2. Major Research Subjects(1) Liquid lithium target for production of neutron or muon
(2) Beam window without solid structure

3. Summary of Research Activity(1) Liquid lithium target for production of neutron or muon (H. Okuno)(2) Beam window with solid structure (H. Okuno)

Members
Team Leader
Hiroki OKUNO
Visiting Scientist
Katsuyoshi TSUMORI (Nat’l Inst. Fusion Science)

List of Publication
Publication[Original Paper]
Y. Miyake et al., “Test of 107 Pd transmutation with macroscopic quantities,” J. Nucl. Sci. Technol. 59, 1536 (2022).

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Research Facility Development Division
Accelerator Group
1. Abstract

The Accelerator Group, consisting of seven teams, pursues various upgrade programs on the world-leading heavy-ion accelerator
facility, RI Beam Factory (RIBF), to enhance the accelerator performance and operation eﬃciency. The programs include the R&D of
superconducting ECR ion source, charge stripping systems, beam diagnostic devices, radio-frequency systems, control systems, andbeam simulation studies. We are also maintaining the large infrastructure to realize eﬀective operation of the RIBF. Moreover, we are
actively promoting the applications of the facility to various research ﬁelds.
Our primary mission is to supply intense, stable heavy-ion beams for the users through eﬀective operation, maintenance, andupgrade of the RIBF accelerators and related infrastructure. The director members oversee the development programs that are notdealt with by a single team, such as intensity upgrade and eﬀective operation. We also discuss the future plans of RIBF along withother laboratories belonging to the RIBF research division.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Intensity upgrade of RIBF accelerators (Okuno)
Eﬀective and stable operation of RIBF accelerators (Fukunishi)
Stable operation of the upgraded RILAC facility
Promotion of applied research through collaborations
Promotion of the RIBF upgrade plan

3. Summary of Research Activity(1) 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, we succeeded in accelerating the zinc beam of 830 particle nA through SRC in
December 2022, which corresponds to the beam power of 20 kW.
(2) In December 2022, the high intensity zinc beam damaged the beam pipe in the last magnetic deﬂection channel (MDC3)
in SRC, causing a vacuum leak and stopping beam service. We plan to repair the damaged part, investigate the cause, andimplement remedial measures.
(3) In the upgraded RILAC, replacement of the low-level rf control units has been carried out with newly developed ones basedon digital circuit technology. The temperature control device for the cooling water in the normal-conducting cavity has been
improved, and the accuracy of the temperature has been dramatically improved. Pulsed-rf conditioning of the superconducting
cavities, where ﬁeld emission had become severe, was also successfully performed. So far, a high-intensity vanadium beam
has been stably supplied to the experiments for the synthesis of a new superheavy element.
(4) We have supplied a wide variety of beams for applied research aimed at solving social problems, such as ion beam breeding,irradiation of semiconductors for space applications, and radioactive isotope production. Since 2017, we have cooperated in
producing and supplying At-211 to various research activities. In particular, we contributed to the initiation of a physician-led
clinical trial at Osaka University in 2021. A high-power target for mass production of At-211 is under development with RI
Application Research Group of RNC, using the high-intensity alpha beam from RRC. It will be installed and tested in the
SRILAC facility in near future.
(5) An intensity-upgrade plan of the RIBF has been further investigated. The main focus of this plan is to increase the eﬀective
transmission eﬃciency of the accelerator chain from the current 5% to 50% by installing two Charge Stripper Rings (CSRs).
The ﬁnal goal of this plan is to increase the uranium beam intensity by 20 times of the present value, namely up to 2000 particle nA, at the exit of SRC. Detailed orbit calculations for the ﬁrst of these CSRs have progressed, and design, prototyping,
and testing of focusing and extraction magnets have been carried out with the involvement of companies. Good results havebeen obtained so far. In 2022, a detailed study of the entire plan, including the elements other than CSR, was initiated byyoung group members.

Members
Director
Osamu KAMIGAITO
Deputy Directors
Hiroki OKUNO (for intensity upgrade)

Nobuhisa FUKUNISHI (for stable and eﬃcient operation)

Research Consultants
Tadashi FUJINAWA

Masayuki KASE

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Visiting Scientists
Eiji KAKO (KEK)
Hirotaka NAKAI (KEK)
Kensei UMEMORI (KEK)
Hiroshi SAKAI (KEK)

Masahiro OKAMURA (BNL)
Noboru SASAO (Okayama Univ.)
Yasutaka IMAI (Okayama Univ.)

Assistant
Karen SAKUMA
Administrative Part-time Worker
Ryoko UMEZAKI

List of Presentation
Presentation[International Conference/Workshop]
O. Kamigaito (invited), “High beam power operations at RIKEN RIBF: Technical developments, challenges and resolutions,” 15th International Conference on Heavy Ion Accelerator Technology (HIAT2022), Darmstadt, Germany, June 27–July 1, 2022.

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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 charge strippers for high power beams, such as low-Z gas
stripper, highly oriented graphene ﬁlms and liquid lithium ﬁlms. 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 (highly oriented graphene ﬁlm, low-Z gas, liquid lithium ﬁlms)(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, liquid lithium ﬁlm)
(H. Hasebe, H. Imao, Y. Miyake, and H. Okuno)
We are developing the charge strippers for high intensity heavy ion beams. We are focusing on the developments on highlyoriented carbon graphite ﬁlms, gas strippers including He gas stripper and liquid lithium ﬁlms.
(2) Upgrade of the superconducting ring cyclotron(J. Ohnishi, Y. Miyake, and 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, Y. Miyake, and H. Okuno)
We are developing high-performance electrostatic channels for high power beam injection and extraction.

Members
Team Leader
Hiroki OKUNO
Senior Research Scientist
Hiroshi IMAO
Technical Scientists
Hiroo HASEBE

Yasuto MIYAKESpecial Temporary Technical Scientist
Jun-ichi OHNISHI
Visiting Scientist
Noriyosu HAYASHIZAKI (Tokyo Tech)

List of Publication
Publications[Original Papers]
Y. Miyake et al., “Test of 107 Pd transmutation with macroscopic quantities,” J. Nucl. Sci. Technol. 59, 1536 (2022).

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Research Facility Development Division
Accelerator GroupIon Source Team
1. Abstract

Our aim is to operate and develop the ECR ion sources for the accelerator-complex system of the RI Beam Factory. We focus on
further upgrading the performance of the RI Beam Factory through the design and fabrication of a superconducting ECR ion sourcefor production of high-intensity heavy ions.

2. Major Research Subjects(1) Operation and development of the ECR ion sources(2) Development of a superconducting ECR heavy-ion source for production of high-intensity heavy ion beams

3. Summary of Research Activity(1) Operation and development of ECR ion sources(T. Nakagawa, M. Kidera, Y. Higurashi, T. Nagatomo, Y. Kanai, G. M Q. Saquilayan, 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, G. M Q. Saquilayan, 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
Senior Technical Scientists
Yoshihide HIGURASHI

Takashi NAGATOMO

Postdoctoral Researcher
Glynnis Mae Q. SAQUILAYAN
Research Consultant
Yasuyuki KANAI

List of Presentation
Presentation[International Conference/Workshop]
T. Nakagawa (invited), “High performance ECR ion sources development at RIKEN and their impact to heavy ion accelerators,” 23rd
International Conference on Cyclotrons and their Applications (CYC2022), Beijing, China, December 5–9, 2022.

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RIKEN Accel. Prog. Rep. 56 (2023)

Research Facility Development Division
Accelerator GroupRILAC Team
1. Abstract

Our team is responsible for the operation, maintenance, and upgrade of the RIKEN heavy-ion linear accelerator (RILAC), a
unique variable-frequency linac that has been in operation since 1980. RILAC was upgraded in the 1990s as part of the RI Beam
Factory (RIBF) project, and made a signiﬁcant contribution to the synthesis and discovery of the element 113, Nihonium. In 2019,a superconducting linac booster, SRILAC, was installed, and it will play a major role in the synthesis of heavier new elements,
development of the technologies for production of medical radioisotopes, and as a powerful injector to RIBF. We successfully avoided
major troubles by eﬀectively planning and implementing maintenance and upgrades of outdated equipment within a limited budget.

2. Major Research Subjects(1) Eﬃcient operation, maintenance and management of the vacuum equipment in the RIBF accelerators(2) Development of technology to operate RILAC with high intensity and high stability(3) Construction and maintenance of the RILAC beamlines

3. Summary of Research Activity

In 2022 we have made various improvements of the whole RILAC with the cooperation of other teams of the Accelerator Group,in order to provide high-intensity beams more stably to the new element synthesis experiments being conducted at GARIS III. For
example, activate the temperature control of the cooling water system of RILAC. With these eﬀorts, the beam availability has been
improved signiﬁcantly.
A beamline is being prepared at the RILAC facility for mass production of 211 At, which has potential medical applications.
Under the leadership of the RI Application Research Group and with the help of other teams of the Accelerator Group, the optical
calculations, electromagnet design, radiation shielding design, and overall beamline installation were undertaken and the beamline isalmost complete.
As in the past, we maintained the vacuum system of the whole accelerators at RIBF. While taking into consideration the aging of
the vacuum pumps, an eﬃcient maintenance plan was established and cost-conscious maintenance was executed.

Members
Team Leaders
Yoshihide HIGURASHI

Osamu KAMIGAITO

Deputy Team Leader
Naruhiko SAKAMOTO
Research/Technical Scientists
Yutaka WATANABE (Senior Technical Scientist)

Takahiro NISHI (Research Scientist)

Research Consultant
Eiji IKEZAWA

List of Publication & Presentations
Publication[Proceeding]
H. Yamauchi, T. Ohki, K. Oyamada, M. Tamura, Y. Akira, K. Kaneko, T. Nishi, N. Sakamoto, M. Fujimaki, H. Imao, M. Kidera,
T. Nagatomo, K. Ozeki, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada, O. Kamigaito, “Present status of RILAC,”
Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online, Japan, October 18–21,
2022, TFP009, 1144–1147 (2022). https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/TFP0/TFP009.pdf .

Presentations[Domestic Conferences/Workshops]

山内啓資, 西隆博, 大木智則, 小山田和幸, 田村匡史, 遊佐陽, 金子健太, 坂本成彦, 今尾浩士, 内山暁仁, 大関和貴, 須田健嗣, 長友傑,
藤巻正樹, 山田一成, 渡邉環, 渡邉裕, 上垣外修一, 「理研重イオンリニアックの現状報告」, 日本加速器学会, オンライン, 2022 年
10 月 10 日.
T. Nishi (invited), “Development of automatic optical tuning system for primary line using Gaussian process at RIKEN,” ML@HEP,Tokyo, Japan, July, 2022.
T. Nishi, “Development of auto tuning system using Bayesian optimization for heavy ion optics,” Workshop on Machine Learning for
Accelerator and Beam Physics, RCNP, Osaka, March, 2023.

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RIKEN Accel. Prog. Rep. 56 (2023)

Outreach Activity[Lecture]
T. Nishi, “AI based accelerator operation,” KEK IINAS 5th International School on Beam Dynamics and Accelerator Technology, Hiroshima, Japan, October, 2022.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Research Facility Development Division
Accelerator Group
Cyclotron Team
1. Abstract

The mission of the RIKEN Radioactive Isotope Beam Facility (RIBF)1) is to improve our understanding of the mechanism ofelement synthesis in the universe through experiments using intense heavy-ion beams. According to the medium-term targets of the
RNC, our team’s mission is to maintain and improve the highly reliable operation of the RIBF accelerator complex, in collaboration
with other teams of the RNC. The stable operation of the RF system is crucial for handling very high-power beams. Our goal is todevelop a highly reliable/stable radio-frequency (RF) system for RIBF cyclotrons and linacs, enabling high-power beam operations.
Recently, we successfully achieved energy and intensity upgrades for the injector RILAC, which are required for super-heavy element
synthesis experiments, by introducing the superconducting linac SRILAC. After three years of hardware improvements on the linac,
we achieved a beam intensity of 4.2 particle µA with a duty factor of 86%.1) Since FY2021, this team has been assigned to take overthe duties under an outsourcing contract for the operation staﬀ.
Reference

1) K. Yamada et al., Proc. SRF2023.

2. Major Research Subjects(1) Room-temerature and superconducting RF technology for heavy-ion accelerators(2) Development of superconducting linac(3) Operation of RIBF accelerator complex

3. Summary of Research Activity• Room-temperature and superconducting RF technology for heavy-ion accelerators. We have successfully constructed a superconducting linac for the SHE experiment. Thanks to the newly developed digital feedback circuit, the amplitude and phase of theaccelerating electric ﬁeld are highly stabilized. The existing analog feedback circuits for the room-temperature RF system will
be replaced by the newly developed digital feedback circuit.
• After commissioning the hardware of the superconducting linac, the next target is to achieve long-term operation with highreliability. One of the most signiﬁcant issues with superconducting cavities is the increase in ﬁeld emission due to prolonged
operation. We are currently working on ﬁnding a solution to restore the original performance of the superconducting cavity by
utilizing high-power pulsed conditioning.
• User beam services are performed by the operation staﬀ. To ensure eﬀective operation and software and hardware maintenance,a weekly operation meeting is held. During these meetings, problems and diﬃculties are discussed among members of the
hardware groups and the safety management group.

Members
Team Leader
Naruhiko SAKAMOTO
Research/Technical Scientists
Kazutaka OZEKI (Senior Technical Scientist)

Kenji SUDA (Technical Scientist)

List of Publications & Presentations
Publications[Original Paper]
H. Sakai, H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for superheavy-element research at RIKEN,” Eur. Phys. J. A 58,
238 (2022).

[Review Article]
N. Sakamoto and T. Nagatomo, “Superconducting linac booster for super-heavy element experiments at RIKEN radioactive isotope beamfactory,” Nucl. Phys. News 32, 21 (2022).

[Proceedings]
K. Yadomi, K. Ozeki, S. Fukuzawa, M. Hamanaka, S. Ishikawa, K. Kobayashi, R. Koyama, R. Moteki, T. Nakamura, M. Nishida,
M. Nishimura, J. Shibata, N. Tsukiori, T. Adachi, M. Fujimaki, N. Fukunishi, H. Hasebe, Y. Higurashi, H. Imao, O. Kamigaito,
M. Kidera, M. Komiyama, K. Kumagai, T. Maie, Y. Miyake, T. Nagatomo, T. Nakagawa, T. Nishi, J. Ohnishi, H. Okuno, N. Sakamoto,
K. Suda, A. Uchiyama, S. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, K. Kamakura, and Y. Kotaka, “Status report on theoperation of RIKEN AVF cyclotron,” Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu- 295 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

University, Online, Japan, October 18–21, 2022, TWP001, 1075–1078 (2022), https://www.pasj.jp/web_publish/pasj2022/
proceedings/PDF/TWP0/TWP001.pdf .
K. Kobayashi, K. Suda, S. Fukuzawa, M. Hamanaka, S. Ishikawa, R. Koyama, R. Moteki, T. Nakamura, M. Nishida, M. Nishimura,
J. Shibata, N. Tsukiori, K. Yadomi, T. Adachi, T. Dantsuka, M. Fujimaki, T. Fujinawa, N. Fukunishi, H. Hasebe, Y. Higurashi,
E. Ikezawa, H. Imao, O. Kamigaito, Y. Kanai, M. Kidera, M. Komiyama, K. Kumagai, T. Maie, Y. Miyake, T. Nagatomo, T. Nakagawa, M. Nakamura, J. Ohonishi, H. Okuno, K. Ozeki, N. Sakamoto, A. Uchiyama, S. Watanabe, T. Watanabe, Y. Watanabe,
and K. Yamada, “Status report on the operation of RIKEN AVF cyclotron,” Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online, Japan, October 18–21, 2022, TWP003, 1084–1088 (2022), https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/TWP0/TWP003.pdf .
H. Yamauchi, T. Ohki, K. Oyamada, M. Tamura, Y. Akira, K. Kaneko, T. Nishi, N. Sakamoto, M. Fujimaki, H. Imao, M. Kidera,
T. Nagatomo, K. Ozeki, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada, and O. Kamigaito, “Present status of RILAC,”
Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online, Japan, October 18–21,
2022, TFP009, 1144–1147 (2022), https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/TFP0/TFP009.pdf .

Presentations[International Conferences/Workshops]
K. Yamada, “Operational status of SRILAC at RIKEN,” Tesla Technology Collaboration Meeting, Rokkasho, Japan, October 11–14,
2022.
K. Ozeki, “Present stautus of RIKEN power coupler,” Tesla Technology Collaboration Meeting, Rokkasho, Japan, October 11–14, 2022.

[Domestic Conferences/Workshops]
K. Yadomi, K. Ozeki, S. Fukuzawa, M. Hamanaka, S. Ishikawa, K. Kobayashi, R. Koyama, R. Moteki, T. Nakamura, M. Nishida,
M. Nishimura, J. Shibata, N. Tsukiori, T. Adachi, M. Fujimaki, N. Fukunishi, H. Hasebe, Y. Higurashi, H. Imao, O. Kamigaito,
M. Kidera, M. Komiyama, K. Kumagai, T. Maie, Y. Miyake, T. Nagatomo, T. Nakagawa, T. Nishi, J. Ohnishi, H. Okuno, N. Sakamoto,
K. Suda, A. Uchiyama, S. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, K. Kamakura, and Y. Kotaka, “Status report on theoperation of RIKEN AVF cyclotron,” The 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online,
Japan, October 18–21, 2022.
K. Kobayashi, K. Suda, S. Fukuzawa, M. Hamanaka, S. Ishikawa, R. Koyama, R. Moteki, T. Nakamura, M. Nishida, M. Nishimura, J. Shibata, N. Tsukiori, K. Yadomi, T. Adachi, T. Dantsuka, M. Fujimaki, T. Fujinawa, N. Fukunishi, H. Hasebe, Y. Higurashi, E. Ikezawa,
H. Imao, O. Kamigaito, Y. Kanai, M. Kidera, M. Komiyama, K. Kumagai, T. Maie, Y. Miyake, T. Nagatomo, T. Nakagawa, M. Nakamura, J. Ohonishi, H. Okuno, K. Ozeki, N. Sakamoto, A. Uchiyama, S. Watanabe, T. Watanabe, Y. Watanabe, and K. Yamada, “Status
report on the operation of RIKEN AVF cyclotron,” The 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online, Japan, October 18–21, 2022.
H. Yamauchi, T. Ohki, K. Oyamada, M. Tamura, Y. Akira, K. Kaneko, T. Nishi, N. Sakamoto, M. Fujimaki, H. Imao, M. Kidera,
T. Nagatomo, K. Ozeki, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada, and O. Kamigaito, “Present status of RILAC,”
The 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online, Japan, October 18–21, 2022.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

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 develops
power supplies, beam instrumentation, computer control, and beam dynamic studies. We have successfully increased the beam
availability for user experiments to over 98%. We have also established small-beam-loss operations, which strongly contribute torecent high-power operations at RIBF.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Eﬃcient and stable operations of the RIBF cascaded cyclotron system
Maintenance and development of the beam instrumentation
Developments of the 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 a few tens of kW

3. Summary of Research Activity(1) High-intensity heavy-ion beams such as 117-particle-nA (particle nA) uranium, 173-particle nA xenon, 690-particle nA
krypton, 830-particle nA Zinc and, 740-particle nA calcium beams, have been obtained.
(2) The world-ﬁrst high-Tc SQUID beam current monitor has been developed. The Beam Energy and Position Monitor has
been successfully developed and introduced into the beamline of the superconducting rilac (SRILAC). Construction of a new
Faraday cup capable of withstanding 50-kW beams is nearly completed by the end of FY2022.
(3) The replacement and upgrade of the old power supplies used in Riken Ring Cyclotron (RRC) are in progress. Two-thirdsof the outdated power supplies that energize the trim coils of RRC have been replaced with new ones. The power supplies
applying currents to beam injection and extraction systems have been upgraded in their current feedback systems, improving
long-term stability.
(4) The new beam interlock system with a response time of less than 1 ms has been successfully developed utilizing National
Instruments’ CompactRIO technology.
(5) The RIBF control system has been operated stably by replacing legacy hardware controllers inherited from our old facility
with new ones. Several useful operation tools are also developed.

Members
Team Leader
Nobuhisa FUKUNISHI
Senior Technical Scientists
Masaki FUJIMAKI
Kazunari YAMADA
Taihei Adachi

Tamaki WATANABE
Akito UCHIYAMA

Expert Technician
Misaki KOMIYAMA
Research Associate
Hiroki FUJIISpecial Temporary Technical Scientist
Keiko KUMAGAI
Visiting Scientists
Shin-ichiro HAYASHI (Hiroshima Int’l Univ.)
Atsushi KAMOSHIDA (Nat’l Instruments Japan Corporation)

Takuya MAEYAMA (Kitasato Univ.)

List of Publications & Presentations
Publications[Original Paper]
T. Maeyama, A. Mochizuki, K. Yoshida, N. Fukunishi, K. L. Ishikawa, and S. Fukuda, “Radio-ﬂuorogenic nanoclay gel dosimeters with
reduced linear energy transfer dependence for carbon beam radiotherapy,” Med. Phys. 50, 1073 (2023). https://doi.org/10.1002/
mp.16092 .

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)[Proceedings]
T. Watanabe, A. Kamoshida, T. Nishi, A. Uchiyama, and K. Kaneko, “Beam proﬁle measurement using helium gas light emission forsuperheavy element search experiment,” Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan, October
18–21, 2022, Online (Kyushu University), Japan, p. 764.
A. Uchiyama A. M. Kidera, M. Komiyama, and K. Kaneko, “Deployment of archiver appliance to RIBF control system,” Proceedings ofthe 19th Annual Meeting of Particle Accelerator Society of Japan, October 18–21, 2022, Online (Kyushu University), Japan, p. 9.
K. Yamada, “Upgrade and current status of high-frequency systems for RIKEN Ring Cyclotron,” Proc. 23rd International Conference on
Cyclotrons and their Applications (CYC2022), Beijing, China, December 5–9, 2022, MOAI02.
A. Uchiyama, K. Kumagai, M. Komiyama, and N. Fukunishi, “Evaluation of PLC-based EtherNet/IP communication for upgrade ofelectromagnet power supply control at RIBF,” Proc. 23rd International Conference on Cyclotrons and their Applications (CYC2022),
Beijing, China, December 5–9, 2022, TUBO04.

Presentations[International Conferences/Workshops]
K. Yamada (invited), “Upgrade and current status of high-frequency systems for RIKEN Ring Cyclotron,” 23rd International Conference
on Cyclotrons and their Applications (CYC2022), Beijing, China, December 5–9, 2022.
A. Uchiyama (oral), K. Kumagai, M. Komiyama, and N. Fukunishi, “Evaluation of PLC-based EtherNet/IP communication for upgradeof electromagnet power supply control at RIBF,” 23rd International Conference on Cyclotrons and their Applications (CYC2022),
Beijing, China, December 5–9, 2022.

[Domestic Conferences/Workshops]
T. Watanabe (poster), A. Kamoshida, T. Nishi, A. Uchiyama, and K. Kaneko, “Beam proﬁle measurement using helium gas light emission
for superheavy element search experiment,” 19th Annual Meeting of Particle Accelerator Society of Japan, October 18–21, 2022,
Kyushu University, Online, Japan.
A. Uchiyama (oral), M. Kidera, M. Komiyama, and K. Kaneko, “Deployment of archiver appliance to RIBF control system,” 19th Annual
Meeting of Particle Accelerator Society of Japan, October 18–21, 2022, Kyushu University, Online, Japan.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

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)(2) Operation of the helium cryogenic plant in the south area of Wako campus and delivering the liquid helium to users in Wako
campus (T. Dantsuka, S. Tsuruma, M. Kuroiwa, M. Takahashi, H. Okuno).

Members
Team Leader
Hiroki OKUNO
Senior Technical Scientist
Masato NAKAMURA
Technical Scientist
Tomoyuki DANTSUKA
Research Part-time Worker
Mamoru TAKAHASHI
Administrative Part-time Workers
Shizuho TSURUMA

Mayumi KUROIWA

List of Publication & Presentation
Outreach Activity

段塚知志, 「実験を止めない! 理研のヘリウムリサイクル」, クローズアップ科学道 2022, 2022 年 10 月 17 日, https://www.riken.
jp/pr/closeup/2022/20221017_1/index.html .

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Research Facility Development Division
Accelerator Group
Infrastructure Management Team
1. Abstract

Our team oversees the design, operation, and maintenance of the large-scale infrastructure for the entire RI Beam Factory (RIBF),
including cooling water, air conditioning, and electrical equipment, as well as the research and development of their advanced management. In order to operate the RIBF eﬃciently, it is very important to ensure the sound operation of these infrastructures that lead tothe stable functioning of various devices. Another important mission is to coordinate the scheduling of major construction and repair
work related to the RIBF so that beamtime runs smoothly.
The recent issue is the aging of infrastructure equipment. In line with these measures, we are making modiﬁcations that contributeto the stability of accelerator equipment and energy saving. In addition, infrastructure equipment has many sensors for management,
and a huge amount of measurement data from these sensors is archived. We are planning to use this data to build a more advanced
management system.

2. Major Research Subjects(1) Operation, maintenance, and monitoring of infrastructure of RI Beam Factory(2) Development of advanced management of infrastructure that contributes to accelerator and beam stability(3) Coordination of large construction work and modiﬁcation related to RI Beam Factory

Members
Team Leader
Masanori KIDERA
Technical Scientist
Takeshi MAIE
Special Temporary Technical Scientist
Shu WATANABE

List of Publications & Presentations
Publications[Proceedings]

内山暁仁, 金子健太, 木寺正憲, 込山美咲,「アーカイバーアプライアンスの RIBF 制御系への展開」, “Deployment of archiver appliance
to RIBF control system,” Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online,
Japan, October 18–21, 2022, pp. 9–13.
矢冨一慎, 大関和貴, 福澤聖児, 濱仲誠, 石川盛, 小林清志, 小山亮, 茂木龍一, 仲村武志, 西田稔, 西村誠, 柴田順翔, 月居憲俊, 足立泰平,
藤巻正樹, 福西暢尚, 長谷部裕雄, 日暮祥英, 今尾浩士, 上垣外修一, 木寺正憲, 込山美咲, 熊谷桂子, 真家武士, 三宅泰斗, 長友傑, 中川孝秀, 西隆博, 大西純一, 奥野広樹, 坂本成彦, 須田健嗣, 内山暁仁, 渡部秀, 渡邉環, 渡邉裕, 山田一成, 鎌倉恵太, 小高康照, 「理研 AVF サイクロトロン運転の現状報告」, “Status report on the operation of RIKEN AVF cyclotron,” Proceedings of the 19th Annual
Meeting of Particle Accelerator Society of Japan, Kyushu University, Online, Japan, October 18–21, 2022, pp. 1075–1078.
小林清志, 須田健嗣, 福澤聖児, 濱仲誠, 石川盛, 小山亮, 茂木龍一, 仲村武志, 西田稔, 西村誠, 柴田順翔, 月居憲俊, 矢冨一慎, 足立泰平,
段塚知志, 藤巻正樹, 藤縄雅, 福西暢尚, 長谷部裕雄, 日暮祥英, 池沢英二, 今尾浩士, 上垣外修一, 金井保之, 木寺正憲, 込山美咲,
熊谷桂子, 真家武士, 三宅泰斗, 長友傑, 中川孝秀, 中村仁音, 大西純一, 奥野広樹, 大関和貴, 坂本成彦, 内山暁仁, 渡部秀, 渡邉環,
渡邉裕, 山田一成,「理研 RIBF におけるリングサイクロトロンの運転報告」, “Status report of the operation of RIBF ring cyclotrons,”
Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online, Japan, October 18–21,
2022, pp. 1084–1088.
山内啓資, 西隆博, 大木智則, 小山田和幸, 田村匡史, 遊佐陽, 金子健太, 坂本成彦, 今尾浩士, 内山暁仁, 大関和貴, 木寺正憲, 須田健嗣,
長友傑, 藤巻正樹, 山田一成, 渡邉環, 渡邉裕, 上垣外修一, 「理研重イオンリニアックの現状報告」, “Present status of RILAC,”
Proceedings of the 19th Annual Meeting of Particle Accelerator Society of Japan, Kyushu University, Online, Japan, October 18–21,
2022, pp. 1144–1147.

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RIKEN Accel. Prog. Rep. 56 (2023)

Research Facility Development Division
Instrumentation Development Group
1. Abstract

This group develops the core-experimental instruments at the RI Beam Factory. Three projects are currently going on. SCRIT is
the world’s ﬁrst experimental facility for electron scattering of unstable nuclei and was constructed oﬀ the main beamline of RIBF.
The ﬁrst physic result was demonstrated in 2017. After years of developments and improvements, the world’s ﬁrst electron scatteringexperiment with online-produced radioactive isotopes has been successfully conducted in 2022. An upgrade of the electron beam
power that drives RI beam production is currently underway. The Rare-RI Ring is an event-by-event-operated heavy ion storage ringfor precise mass measurement of extremely rare exotic nuclei. It is currently accepting applications for experimental proposals and has
already conducted PAC-approved experiments and published its ﬁrst physics results. In 2022, we conﬁrmed that the new capacitorsof the kicker-magnet system worked well during long-time test. Thus, the problem in the operation has been solved so far. Moreimprovements are currently underway to achieve more precise mass measurements and stable operation. The compact heavy-ion
storage ring RUNBA is an R&D machine for the development of beam recycling techniques for nuclear reaction research on rareelements. This is currently under construction and some of the critical components of the ring are currently undergoing technicaldevelopment.
All instrumentations are designed to maximize the research potential of the world’s most intense RI beams, and dedicated RI
Beam Factory equipment makes the experimental challenge possible. The experimental technique and experience accumulated in thisgroup provide opportunities for new experimental challenges and form the basis for the future development of the RIBF.

2. Major Research Subjects(1) SCRIT Project (electron scattering oﬀ unstable nuclei)(2) Rear RI Ring Project (precise mass measurement)(3) RUNBA project (Beam recycling techniques)

3. Summary of Research Activity

We are developing beam manipulation techniques to carry out the above projects. These are high-quality slow RI beam generation
technology (SCRIT), beam cooling and stopping technology (SCRIT) and beam accumulation technology in a storage ring (Rare RI
Ring, RUNBA). The technical know-how accumulated in the project will play a major role in the next generation of RIBF. The current
status and future plans for SCRIT and Rare-RI Ring are described in the respective sections.
In 2022, we successfully conducted the world’s ﬁrst electron scattering experiment with online-produced unstable nuclei, which is
137
Cs isotopes, through years of the developments and improvements. We are in the process of power upgrading of the electron beamfrom the RTM, which is the driving for RI production, and expanding the nuclei that can be accessed. The Rare RI Ring is an eventby-event based mass measurement system, designed speciﬁcally for extremely low-producing isotopes. We carried out PAC-approved
experiments and successfully measured the masses of 74, 76 Ni, 122 Rh, 123, 124 Pd and 125 Ag for the ﬁrst time. To improve mass resolution
and eﬃciency, the ﬁrst-response kicker system and optical tuning system are being improved. To ensure stable operation, the newcapacitors were tested with a kicker manet system with good results. According to the future plans of Nishina center, a beam re-cycling
technique is under development. Beam recycling technology allows the circulation of RI beams to be maintained in a storage ringwith a thin internal target until a nuclear reaction occurs. In order to establish beam recirculation, the increase in energy width andemittance needs to be compensated for using a fast feedback system. We have demonstrated the possibility of compensation in ananalytical way and found the properties of EDC and ADC devices necessary for compensation. To develop these new technologies,
a compact heavy ion storage ring (RUNBA) connected to ISOL (ERIS) is under construction at the SCRIT facility. Under a researchcooperation agreement with ICR in Kyoto University, technical development of the main components required for RUNBA i.e. thecharge breeder, energy dispersion corrector, angular diﬀusion corrector and internal target system are underway. We developed theprototype devices for EDC and ADC devices, and further improvements are ongoing. Furthermore, we also developed the simulation
code based on the analytical model, and evaluated the performance of RUNBA.

Members
Directors
Tetsuya OHNISHI

Masanori WAKASUGIContract Researcher
Ryo OGAWARA
Visiting Scientists
Shun IIMURA (Rikkyo Univ.)
Daisuke NAGAE (Tokyo Tech)
Ryo OGAWARA (Kyoto Univ.)
Akira OZAWA (Tsukuba Univ.)

Fumi SUZAKI (JAEA)
Kyo TSUKADA (Kyoto Univ.)
Masanori WAKASUGI (Kyoto Univ.)- 301 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Student Trainees
Yuki ITO (Kyoto Univ.)
Yusei MAEDA (Kyoto Univ.)
Yoshiki MAEHARA (Kyoto Univ.)
Mariko TACHIBANA (Kyoto Univ.)

Fuuma TOUJOU (Rikkyo Univ.)
Tsubasa YAMANO (Rikkyo Univ.)
Satoru YOSHIDA (Kyoto Univ.)

Administrative Part-time Worker
Midori TAKEMON

List of Publication & Presentations
Publication[Review Article]
M. Wakasugi, Y. Abe, Y. Ito, T. Ohnishi, R. Ogawara, K. Kuze, S. Takagi, K. Tsukada, H. Tongu, Y. Maehara, and Y. Yamaguchi,“Recycled-Unstable-Nuclear Beam Accumulator (RUNBA) for developing beam recycling technique toward the study of nuclear reaction for rare RIs,” J. Part. Accl. Soc. Jpn. 19, 25 (2022).

Presentations[Domestic Conferences/Workshops]

小川原亮 (口頭発表), 「RI-RI 反応実験を目的としたビームリサイクル技術開発用蓄積リング（RUNBA）の動作原理」, 日本物理学会 第 77 回年次大会, オンライン, 2022 年 3 月 15–19 日.
小川原亮 (口頭発表), 「ビームリサイクル技術開発を目的とした重イオン蓄積リング RUNBA の動作原理」, 第 19 回日本加速器学会年会, オンライン, 2022 年 10 月 18–21 日.

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RIKEN Accel. Prog. Rep. 56 (2023)

Research Facility Development Division
Instrumentation Development GroupSLOWRI Team
1. Abstract

The SLOWRI team develops, operates and improves SLOW RI beam production devices and related systems, and uses thesedevices and systems to conduct experimental programs at RIBF. As the heart of SLOWRI, we have developed RF carpet type cryogenic He gas catchers (RFGC). Two RFGCs are currently in operation to deliver slow RI beams converted from fast RIs producedwith fragmentation or inﬂight ﬁssion on RIPS and BigRIPS. These RFGCs are directly combined with muti-reﬂection time-of-ﬂight
mass spectrographs (MRTOF-MS) for precise mass measurements tailored to user’s experimental programs. Especially, the RFGC
combined with a MRTOF-MS installed behind ZeroDegree spectrometer of BigRIPS is being operated symbiotically reusing RIs fromother experiment conducted upstream without extra costs. To date, masses on more than 80 RIs provided with BigRIPS have beensuccessfully measured. A lot of user’s experimental programs for precise mass measurements will be conducted in SLOWRI projectsoon. An Ar gas catcher at F2 of BigRIPS was also installed to rescue RI that would otherwise be discarded without being used forexperiments. The RI is caught with the Ar gas catcher, laser resonant ionized and delivered as a slow RI beam in parasitic operating
mode (PALIS). The oﬀ- and online-commissioning of PALIS is underway.

2. Major Research Subjects(1) Development, operation and upgrade of SLOW RI beam production devices and related systems(2) Development and operation of multi-reﬂection time-of-ﬂight mass spectrographs and to conduct precision mass measurementsof short-lived nuclei(3) Development of a parasitic slow RI beam production method using resonance laser ionization

3. Summary of Research Activity(1) Development of RF carpet type cryogenic He gas catchers (RFGCs)
The fast (>100 MeV/nucleon) RI beams can be stopped in helium gas and extracted as slow (<100 eV) RI beams from a RF
carpet type cryogenic He gas cell (RFGC). At RIBF, two RFGCs are in operation at the SLOWRI project: one is a 30-cm-long RFGC
consisting of DC ring electrodes and a RF carpet. It is located behind GARIS-II at E6 of RIBF and is used in combination with a
MRTOF-MS for precise mass measurements of superheavy nuclides. Also, a 9 MBq 252 Cf ﬁssion source has recently been installed
just in front of the He gas catcher. Even oﬀ-line, mass measurements on ﬁssion fragments have continued and several ﬁrst massmeasurements were performed.
Second one is a 50-cm-long RFGC installed behind ZeroDgree spectrometer of BigRIPS. This RFGC contains a three stage RFcarpet 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 (2nd carpet) for collection of ions from the gutter carpet and for transporting the ions towards the exit, and asmall RF carpet for extraction from the gas cell. The oﬀ-line test has been completed in FY2019. The on-line commissioning has beensuccessfully performed symbiotically using RIs provided with BigRIPS during HiCARI campaign in FY2020. During the on-line
commissioning, precise mass measurements were also performed. In FY2021, the ﬁrst experiment approved in NP-PAC of RNC has
been performed, which has aimed the mass measurement in the vicinity of the double magic nucleus of 78 Ni. As the result, masses of74
Ni and 75 Ni have been measured with high precision less than 20 keV. In FY 2022, a 248 Cm source has been installed just behindthe mylar window of the gas cell. The measured extraction eﬃciencies on the ﬁssion products emitted from the source after stoppingin the He gas have been currently reached several to about 30% of the sum of singly-, doubly- and triply-charged ions, depending onelements. Several improvements in order to improve the eﬃciencies are underway using the ﬁssion fragments from the source. Massmeasurements on experimental programs already approved in NP-PAC of RIBF will be performed soon. A ﬁnal version of the RFGC,
1 m long and with increased helium gas pressure, is also in preparation and will be installed in SD4 at BigRIPS.
(2) Conduct of precise mass measurements using MRTOF-MSs combined with RFGCs
The MRTOF, called as SHE-MASS, is combined with the RFGC behind GARIS-II of E6. Mass measurements of superheavy
elements of Db isotopes have been conducted. As a result, the mass on 257 Db superheavy nucleus was determined for the ﬁrst time.
The mass measurements on superheavy nuclide, proton rich nuclide and ﬁssion products emitted from intense Cf source have been
performed.
The MRTOF-MS, called as ZD-MRTOF, is located behind ZDS of BigRIPS in combination with the 50 cm-long RFGC. Currently,
the mass resolving power has been reached at 1 million. Since the location of the ZD-MRTOF is just in front of the beam dump of
ZDS, mass measurements have been conducted symbiotically re-using RIs from other experiment conducted upstream without extra
costs. To date, the masses on more than 80 RIs provided from BigRIPS have been measured. Among them, three isotope masses havebeen measured for the ﬁrst time and mass uncertainties of eleven isotope have been signiﬁcantly improved from the previous ones.
For example, the mass uncertainties have been reduced down to the order of 10 keV for 56, 58 Ti and 56–59 V and nonexistence of the N= 34 empirical two neutron shell-gaps on Ti and V isotopes are revealed experimentally with the new precision achieved.
We have a plan to increase this versatile and portable instrumentation at RIBF: an MRTOF-MS is being installed behind GARISIII, and a plan is underway to install an MRTOF-MS with the RFGC behind SD4 at BigRIPS, which will lead to more opportunities
to study unexplored nuclear species.

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RIKEN Accel. Prog. Rep. 56 (2023)(3) Development of a parasitic slow RI beam production method using resonance laser ionization (PALIS)
More than 99% of RIs produced in projectile ﬁssion or fragmentation at BigRIPS of RIBF are simply dumped into the ﬁrst dipole
magnet and the slits. The SLOWRI project proposed a new method called PALIS, which uses a compact Ar gas catcher and resonant
laser ionization to rescue such precious RI. The thermalized RIs 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 selectively. PALIS is located at
F2 of BigRIPS and is undergoing oﬀ- and on-line commissioning.
At F2, due to high radiation from a beam dump, it was found to be not easy to handle ions using electric ion guides. Therefore,a 70-cm-long gas pipe from the Ar gas cell was newly installed to transport RIs to relatively low radiation area thanks for the Ar gas
ﬂow. In FY2021, we have conﬁrmed the transport of ions of interest downstream of the ion guide behind the gas pipe using α-emitting
Ac isotopes provided with BigRIPS. Also, we have found a lot of contaminant ions from the gas cell, which are originated from
impurities in the gas. To reduce the inﬂuence of such contaminant, a quadrupole mass ﬁlter has been installed downstream of the ion
guide. In FY2023, an on-line test for resonant laser ionization is planned.

Members
Team Leader
Hironobu ISHIYAMA
Senior Research Scientist
Takao KOJIMA
Research Scientist
Aiko TAKAMINETechnical Scientist
Tetsu SONODA
Research Consultant
Hideki IIMURA
Visiting Scientists
Minoru TANIGAKI (Kyoto Univ.)

Hideki TOMITA (Nagoya Univ.)

List of Publications & Presentations
Publications[Original Papers]
S. Iimura, M. Rosenbusch, A. Takamine, Y. Tsunoda, M. Wada, S. Chen, D. S. Hou, W. Xian, H. Ishiyama, S. Yan, P. Schury, H. Crawford,
P. Doornenbal, Y. Hirayama, Y. Ito, S. Kimura, T. Koiwai, T. M. Kojima, H. Koura, J. Lee, J. Liu, S. Michimasa, H. Miyatake,J. Y. Moon, S. Nishimura, S. Naimi, T. Niwase, A. Odahara, T. Otsuka, S. Paschalis, M. Petri, N. Shimizu, T. Sonoda, D. Suzuki,
Y. X. Watanabe, K. Wimmer, and H. Wollnik, “A new study of the N = 32 and N = 34 shell gap for Ti and V by the ﬁrst high-precision
MRTOF mass measurements at BigRIPS-SLOWRI,” Phys. Rev. Lett. 130, 012501 (2023).
M. Rosenbusch, M. Wada, S. Chen, A. Takamine, S. Iimura, D. Hou, W. Xian, S. Yan, P. Schury, Y. Hirayama, Y. Ito, H. Ishiyama,
S. Kimura, T. Kojima, J. Lee, J. Liu, S. Michimasa, H. Miyatake, M. Mukai, J. Y. Moon, S. Nishimura, S. Naiumi, T. Niwase,
T. Sonoda, Y. X. Watanabe, and H. Wolnik, “The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN’s
RIBF facility,” Nucl. Instrum. Methods Phys. Res. B 1047, 167824 (2023).
Y. Hirayama, M. Mukai, Y. X. Watanabe, P. Schury, H. Nakada, J. Y. Moon, T. Hashimoto, S. Iimura, S. C. Jeong, M. Rosenbusch,
M. Oyaizu, T. Niwase, M. Tajima, A. Taniguchi, M. Wada, and H. Miyatake, “In-gas-cell laser resonance ionization spectroscopy of200, 201
Pt,” Phys. Rev. C 106, 034326 (2022).

Presentations[International Conferences/Workshops]
S. Iimura (invited), “A new study of N = 34 subshell structure probed by high-precision mass measurements,” JSPS/NSFC/NRF A3
Foresight Program, “Nuclear Physics in the 21st Century,” Osaka, Japan, February 13–15, 2023.
A. Takamine, M. Rosenbusch, M. Wada, S. Iimura, D. Hou, W. Xian, S. Chen, J. M. Yap, H. Ishiyama, P. Schury, S. Nishimura, T. Niwase,
S. Kimura, Y. Hirayama, Y. Ito, T. M. Kojima, J. Lee, J. Liu, S. Michimasa, H. Miyatake, J. Y. Moon, M. Mukai, S. Naimi, T. Sonoda,
H. Ueno, P. Vi, Y. X. Watanabe, S. Yan, T. T. Yeung, and H. Wollnik, “Development of the new helium gas catcher and nuclear massmeasurements with the new MRTOF-MS system behind the ZeroDegree spectrometer at RIKEN BigRIPS,” The 19th International
Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022), Daejong, Korea, October 3–7, 2022.
M. Rosenbusch, M. Wada, S. Chen, A. Takamine, S. Iimura, D. Hou, W. Xian, S. Yan, P. Schury, Y. Hirayama, Y. Ito, H. Ishiyama,
S. Kimura, J. Lee, J. Liu, S. Michimasa, H. Miyatake, J. Y. Moon, S. Nishimura, S. Naimi, T. Niwase, Y. X. Watanabe, P. Vi, H. Wollnik, and J. M. Yap, “High-precision MRTOF mass measurements of radioactive isotopes at RIKEN’s RIBF facility: Recent projects
for mirror potentials, wideband mass accuracy, and ion selection,” The 19th International Conference on Electromagnetic Isotope
Separators and Related Topics (EMIS 2022), Daejong, Korea, October 3–7, 2022.

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RIKEN Accel. Prog. Rep. 56 (2023)

M. Rosenbusch, “Exploring exotic nuclei by high-precision MRTOF mass measurements: The new ion catcher and mass spectrographat RIKEN’s RIBF facility,” The 8th International Conference on Trapped Charged Particles and Fundamental Physics (TCP 2022),
Glashütten, Germany, September 25–30, 2022.
H. Ishiyama, “Toward mass measurement of neutron-rich nuclei in the vicinity of N = 126,” Workshop for Uniqueness of the 208 Pb beam
at RIBF, Online, September 27, 2022.
M. Rosenbusch (invited), “New nuclear masses, recent and present developments, and future opportunities of the MRTOF-MS at the
ZeroDegree spectrometer,” RIBF Users Meeting 2022, Online, September 20–22, 2022.
S. Iimura (invited), “A new study of the N = 32 and N = 34 shell gap for Ti and V by the ﬁrst high-precision MRTOF mass measurements
at BigRIPS-SLOWRI,” RIBF Users Meeting 2022, Online, September 20–22, 2022.
A. Takamine (invited), “Nuclear mass measurements with the new MRTOF-MS system at the ZeroDegree spectrometer of BigRIPS,”
28th International Nuclear Physics Conference (INPC 2022), Cape Town, South Africa, September 11–16, 2022.
H. Ishiyama (invited), “Present status of SLOWRI,” SSRI-PNS collaboration meeting 2022, Online, September 1–2, 2022.

[Domestic Conferences/Workshops]
M. Rosenbusch, S. Iimura, A. Takamine, Y. Tsunoda, M. Wada, S. Chen, D. S. Hou, W. Xian, H. Ishiyama, S. Yan, P. Schury, H. Crawford,
P. Doornenbal, Y. Hirayama, Y. Ito1, S. Kimura, T. Koiwai, T. M. Kojima, H. Koura, J. Lee, J. Liu, S. Michimasa, H. Miyatake,J. Y. Moon, S. Naimi, S. Nishimura, T. Niwase, A. Odahara, T. Otsuka, S. Paschalis, M. Petri, N. Shimizu, T. Sonoda, D. Suzuki,
Y. X. Watanabe, K. Wimmer, and H. Wollnik, “The SLOWRI/MRTOF-MS project at BigRIPS/ZeroDegree,” 日本物理学会 2022 年度
春季年会, オンライン, 2023 年 3 月 23–25 日.
飯村俊, M. Rosenbusch, 高峰愛子, 和田道治, S. Chen, D. Hou, J. Liu, W. Xian, S. Yan, P. Schury, 木村創大, 庭瀬暁隆, 伊藤由太, 園田哲, 小島隆夫, 渡辺裕, 平山賀一, 宮武宇也, S. Naimi, 道正新一郎, 西村俊二, 小田原厚子, 石山博恒, 角田佑介, 清水則孝, 大塚孝治,「BigRIPS SLOWRI における ZD-MRTOF 装置を用いた中性子過剰 Sc, Ti, V 核の系統的核構造研究」, 日本物理学会 2022 年度秋
季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
庭瀬暁隆, 渡辺裕, 平山賀一, 向井もも, P. Schury, A. N. Andreyev, 飯村俊, 石山博恒, 鄭淳讃, 宮武宇也, M. Rosenbusch, 谷口秋洋,
和田道治, 「精密質量測定による新同位体 241 U の発見」
, 日本物理学会 2022 年度秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月
6–8 日.

[Seminar]

M. Rosenbusch (invited), “A ﬁrst review of the SLOWRI-MRTOF mass spectrograph following the ZeroDegree spectrometer at BigRIPS,”RIBF seminar, Wako, Japan, February 14, 2023.

Press Release

マルコローゼンブッシュ, 飯村俊, 他, 「チタン・バナジウム中性子過剰同位体で新魔法数の消失を観測—精密質量測定による原子核構造のより深い理解に期待—」, KEK, RIKEN, 大阪大学, 2023 年 1 月 6 日.

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RIKEN Accel. Prog. Rep. 56 (2023)

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 path (rare-RI) is required in nucleosynthesis point of view.
Through the commissioning experiments by 2017, we conﬁrmed the high ability of R3 as a storage ring capable of handling one event,and demonstrated that it is possible to perform the time-of-ﬂight Isochronous Mass Spectrometry (IMS) in shorter than 1 millisecond.
In 2018, we performed mass measurement experiments for the ﬁrst time. In 2020, the kicker system was modiﬁed to ﬂatten themagnetic ﬁeld distribution, and the performance study using unstable nuclei was successfully conducted. In 2021, we performed massmeasurement experiments using the upgraded kicker system. The results of the experiment dispelled concerns about the results of theprevious experiment that the injection angle might greatly aﬀected the accuracy of the mass determination. On the other hand, a failure
occurred in the kicker power supply that interfered with the progress of experiments. The cause of the failure was investigated andresolved in this ﬁscal year. We have plan to conduct a beam test to conﬁrm the stable operation of the kicker system before resuming
the mass measurement experiments.

2. Major Research Subjects(1) Further improvement of mass measurement eﬃciency and precision(2) Precision mass measurement for rarely produced isotopes related to r-process

3. Summary of Research Activity

In the commissioning experiments up to 2017, we conﬁrmed the unique performances of R3 and demonstrated the time-of-ﬂight
isochronous mass measurement method. We have realized in forming the precise isochronous ﬁeld of less than 5 ppm with wide
momentum range of ∆p/p = ±0.5%. Another performance required for R3 is to eﬃciently seize hold of an opportunity of the massmeasurement for rare-RIs produced unpredictably. It was realized by constructing the Isotope-Selectable Self-trigger Injection (ISSI)
scheme which pre-identiﬁed rare-RI itself triggers the injection kicker magnets. Key device was a 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 froman originating point (F3 focal point in BigRIPS) of the trigger signal to the kicker position in R3.
Since R3 circulates, in principle, only one event, we fabricated high-sensitive beam diagnostic devices in the ring. One of them isa cavity type of Schottky pick-up installed in a straight section of R3. The Schottky pick-up successfully monitored a single 78 Kr36+
ion circulation with the measurement time of less than 10 milliseconds in the ﬁrst commissioning experiment. We also conﬁrmed that
it is useful for ﬁne tuning of the isochronous ﬁeld.
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 deduced with the accuracy of several ppm. In addition, we have
improved the extraction eﬃciency to 2% by considering the matching condition between the emittance of injection events and theacceptance of R3 in the fourth commissioning experiment. This extraction eﬃciency was suﬃcient to conduct the accepted two
proposals: mass measurements of Ni isotopes and south-west region of 132 Sn.
In November 2018, we conducted the ﬁrst experiment using R3 to measure the masses for 74, 76 Ni in 4 days. After that, we alsomeasured the masses for 122 Rh, 123, 124 Pd, and 125 Ag in 4.5 days. These nuclei were successfully extracted from R3 with the eﬃciency
of 1–2%. However, unexpected deviation from the evaluated values of literature remained in the masses obtained by detailed analysis.
This was thought to be due to the following two reasons. One is that due to the kicker ﬁeld distribution is not ﬂattened, the injection
angle is diﬀerent between the reference and target nucleus, and therefore the relative value of TOF is incorrect. The other is that theabsolute value of beta or magnetic rigidity determined for each extracted event is incorrect.
In 2020, we modiﬁed the kicker system to ﬂatten the magnetic ﬁeld distribution as well as to dispel the concerns of the results ofﬁrst experiment. As a result of performance study using unstable nuclei, we succeeded in forming the kicker ﬁeld with 100 ns ﬂat-top
for injection and long ﬂat-top of 350 ns or more for extraction. The experimental eﬃciency had been improved by a factor of two or
more than previous condition because all nuclides can be extracted at once thanks to the long ﬂat-top.
Using this upgraded kicker system, we measured the mass for 74 Ni again in April 2021. Although the kicker ﬁeld distribution was
ﬂattened, the results of masses were the same as those of the ﬁrst experiment. In other words, concerns about the eﬀects of diﬀerences
in injection angles have been dispelled. As a subsequent analysis, it was clariﬁed that the reason is the second concern described above.
Recently, the mass of 123 Pd was determined precisely and its eﬀect on heavy element synthesis was investigated with collaborators.
We concluded that the composition around 123 Pd observed in the solar system can only be reproduced using the new mass values, andpublished a paper in early 2022. The ﬁnal mass values of other measured nuclei, such as Ni-isotopes, will be determined soon.
The insulation breakdown of a ceramic capacitor used as the charging circuit of the kicker system, which occurred frequently
during the experiment conducted in November 2021, signiﬁcantly aﬀected the progress of the experiment. We investigated the causeof the problem, but found no external factors, and considered the problem to be the capacitor itself. It was diﬃcult to determine theexact cause due to so severe damage, but it was found that the central part of the three-layer structure was particularly damaged inside
the molded resin. Therefore, we decided to use a single-layer capacitor to avoid overheating of the central part. A ﬁve-days continuous
test was conducted in November 2022 to compare the old and new capacitors. As a result, the old capacitor failed again while the new- 306 -

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RIKEN Accel. Prog. Rep. 56 (2023)

capacitor was ﬁne. We will replace all the capacitors and conduct a performance test of the kicker system in 2023.

Members
Team Leaders
Tetsuya OHNISHI

Masanori WAKASUGITechnical Scientist
Yoshitaka YAMAGUCHI

List of Publications & Presentations
Publications[Original Papers]
H. F. Li, S. Naimi, T. M. Sprouse, M. R. Mumpower, Y. Abe, Y. Yamaguchi, D. Nagae, F. Suzaki, M .Wakasugi, H. Arakawa, W. B. Dou,
D. Hamakawa, S. Hosoi, Y. Inada, D. Kajiki, T. Kobayashi, M .Sakaue, Y. Yokoda, T. Yamaguchi, R. Kagesawa, D. Kamioka,
T. Moriguchi, M. Mukai, A. Ozawa, S. Ota, N. Kitamura, S. Masuoka, S. Michimasa, H. Baba, N. Fukuda, Y. Shimizu, H. Suzuki,
H. Takeda, D. S. Ahn, M. Wang, C. Y. Fu, Q. Wang, S. Suzuki, Z. Ge, Yu. A. Litvinov, G. Lorusso, P. M. Walker, Zs. Podolyak,
and T. Uesaka, “First application of mass measurements with the Rare-RI Ring Reveals the solar r-process abundance at A = 122 andA = 123,” Phys. Rev. Lett. 128, 152701 (2022).
ナイミ・サラ, リ・ホンフー, 山口由高, 上坂友洋, 「元素起源の謎解明に向けた超高速質量測定法の実現」, Isotope News 785, 32(2023).

Presentations[Domestic Conferences/Workshops]

山口貴之 (招待講演), 「多価イオンビームによる２光子稀崩壊の観測」, 新学術領域研究「宇宙観測検出器と量子ビームの出会い.
新たな応用への架け橋」, 領域研究会, オンライン, 2022 年 5 月 20–21 日.
篠崎稔 (口頭発表), 「稀少 RI リングのための GAGG:Ce シンチレータを用いた重イオンビーム飛行時間兼全エネルギー検出器の開発」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
神田真矩 (口頭発表), 「稀少 RI リングのためのプラスチックシンチレータと WLS ファイバーを用いた位置検出器の開発」, 日本
物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
大久保研吾 (口頭発表), 「デルタ線を利用した重イオンビーム飛行時間検出器の開発」, 日本物理学会 2023 年秋季大会, オンライ
ン, 2023 年 3 月 15–19 日.
佐々木健太 (口頭発表), 「稀少 RI リングのためのシンチレーションファイバーを用いた位置検出器の開発」, 日本物理学会 2023
年秋季大会, オンライン, 2023 年 3 月 15–19 日.

Press Release「元素起源の謎の解明に向けた世界最速質量測定が始動—稀少 RI リングを用いた短寿命放射性同位体の質量測定に成功—」 , 理
化学研究所, 筑波大学, 埼玉大学, 東京大学, 2022 年 4 月 28 日.

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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. Installation of 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. Through years of developments and improvements,
in 2022, we successfully conducted the world’s ﬁrst electron scattering experiment with online-produced unstable nuclei. Using 137 Csions of 107 ions/pulse at 0.25 Hz, the luminosity was achieved to 0.9 × 1026 /(cm2 s) with about 250 mA-electron beam. In addition, we
started the study of the isotope dependence of charge density distribution using Xe stable isotopes.

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 120–300 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 planned to be 3 kW will be achieved, we can extend the measurements to more exotic nuclei.
In 2018, we developed several instruments. One is the introduction of the surface-ionization type ion source at ERIS in order
to increase kinds of radioactive beam and to produce high intensity beam. Another development is the upgrading of the drift chamber located in front of the magnetic spectrometer of WiSES to improve the momentum resolution and angular acceptance. Thesedevelopments help us to realize experiments for unstable nuclei.
In 2019, we installed a newly designed SCRIT electrodes. The main purpose of the replacement was to lower the background
during the measurement due to the electron scattering from the SCRIT electrodes itself but not from the ion targets for the experiment.
For that purpose, we employed thin metal wires to construct the electrodes rather than metal plates nor blocks. In addition, we- 308 -

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modiﬁed the inside structure of the SCRIT chamber to symmetrize the electric ground potential aﬀecting the potential curve inside theelectrodes.
In 2020, we tested accelerators RTM and SR2 if they bear for long term experiment for 24 hours. In 2021, we commissioned the
new SCRIT electrodes using 138 Ba ion beams produced by the surface-ionization type ion source at ERIS. After the RI production
test, ERIS became ready to provide enough ions for the experiment of unstable nuclei.
In 2022, we successfully conducted the world’s ﬁrst electron scattering experiment with online-produced unstable nuclei. The
137
Cs ion beams, almost 107 ions/pulse at 0.25 Hz, produced by ERIS and FRAC was injected to the SCRIT device, and the luminosity
was reached as 0.9 × 1026 /(cm2 s) with about 250-mA electron beam. Scattering electrons by 137 Cs targets were clearly analyzed andmeasured by WiSES, and the obtained angular distribution of 137 Cs is consistent to the calculated results. The paper will be publishedsoon. In addition, we started the study of the isotope dependence of charge density distribution using Xe stable isotopes. This study
will be expected to help to understand the nuclear structure precisely. First, we measured the angular distribution of 130, 132, 134, 136 Xe
isotopes. Those of remained Xe isotopes, 124, 126, 128 Xe, will be measured soon.

Members
Team Leaders
Tetsuya OHNISHI

Masanori WAKASUGI

Senior Research Scientist
Masamitsu WATANABE
Senior Technical Scientist
Tetsuya OHNISHI
Contract Researcher
Yasushi ABE
Junior Research Associate
Hikari WAUKE
Research Consultants
Takashi EMOTO
Masahiro HARA

Toshitada HORI

Visiting Scientists
Akitomo ENOKIZONO (Rikkyo Univ.)
Yuki HONDA (Tohoku Univ.)
Takahiro IWATA (Yamagata Univ.)

Toshimi SUDA (Tohoku Univ.)
Shuo WANG (Shandong Univ.)

Student Trainees
Daiki ABE (Tohoku Univ.)
Rika DANJO (Tohoku Univ.)
Taiga GOKE (Tohoku Univ.)
Yuma ISHIKURA (Tohoku Univ.)
Clement LEGRIS (Tohoku Univ.)

Evelyn MORRIS (Tohoku Univ.)
Yuka NAGANO (Yamagata Univ.)
Ryo OBARA (Tohoku Univ.)
Hikari WAUKE (Tohoku Univ.)

List of Publications & Presentations
Publications[Original Paper]
T. Suda, “Study of radii of proton and nuclei by electron scattering,” JAEA-Conf 2022-001, 51 (2022).

[Review Article]
T. Suda, “Electron Scattering Oﬀ Stable and Unstable Nuclei,” in Handbook of Nuclear Physics, I. Tanihata, H. Toki, and T. Kajino (eds),(Springer, Singapore, 2023), https://doi.org/10.1007/978-981-15-8818-1_8-1 .

[Proceedings]
J. Bernauer, R. Corliss, S. Gardner, M. Hasinoﬀ, R. Kanungo, J. Martin, R. Milner, K. Pachal, T. Suda, and S. Yen, “Scientiﬁc opportunities
at the ARIEL electron linac,” Proceedings of “Workshop on New Scientiﬁc Opportunities with the TRIUMF ARIEL e-linac,” J. Phys.
Conf. Ser. 2391, 012001 (2022).
T. Suda, “Low-energy electron scattering facilities in Japan,” Proceedings of “Workshop on New Scientiﬁc Opportunities with the TRIUMF ARIEL e-linac,” J. Phys. Conf. Ser. 2391, 012004 (2022).

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Presentations[International Conferences/Workshops]
T. Suda (invited), “Low-energy electron scattering facilities in Japan,” New Scientiﬁc Opportunities with the TRIUMF ARIEL e-linac,
Vancouver, Canada, May 25–27, 2022.
T. Suda (invited), “Low-energy electron scattering—proton radius and beyond,” International STRONG workshop on the Proton Charge
Radius and related topics, Paris, France, June 20–23, 2022.
K. Tsukada (oral), “Electron scattering from unstable nuclei at SCRIT facility,” 28th International Nuclear Physics Conference(INPC2022), Cape Town, South Africa, September 11–16, 2022.
R. Ogawara (poster), “Ion-trapping properties of SCRIT: time evolution of charge state distributions of 138 Ba ions,” The 19th International
Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022), Daejeon, South Korea, October 3–7, 2022.
T. Ohnishi (invited), “The SCRIT electron scattering facility at RIKEN RI Beam Factory,” The 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022), Daejeon, South Korea, October 3–7, 2022.

[Domestic Conferences/Workshops]

塚田曉 (口頭発表), 「電子・不安定核散乱実現に向けた SCRIT 電子散乱施設の現状と展望」, 日本物理学会 2022 年秋季大会, 岡山
市 (岡山理科大), 2022 年 9 月 6–8 日.
小川原亮 (口頭発表), 「SCRIT における 138 Ba 標的の価数分布とその時間発展」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大), 2022 年 9 月 6–8 日.
和宇慶ひかり (口頭発表), 「SCRIT 電子散乱施設における電荷分布の同位体・同調体依存性測定」, 日本物理学会 2022 年秋季大会,
岡山市 (岡山理科大), 2022 年 9 月 6–8 日.
大西哲哉 (口頭発表), 「理研 SCRIT 施設における電子ビーム RI セパレーター ERIS の現状と展望」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大), 2022 年 9 月 6–8 日.
和宇慶ひかり (口頭発表), 「SCRIT 電子散乱施設における電荷分布の同位体・同調体依存性測定」, 日本物理学会 2023 年春季大会,
オンライン, 2023 年 3 月 23 日.

[Seminars]

T. Suda, “Electron scattering and nuclear matrix elements of the double-beta decay process,” 二重ベータ崩壊核行列要に関する実験理論合同研究会, Research Center for Nuclear Physics, Osaka, Japan, October 3–4, 2022.
T. Suda (invited), “Proton Radius,” Australian National University Director’s Colloquium, Canberra, Australia, October 22, 2022.
T. Suda (invited), “Proton Radius,” Physics Colloquium of Univ. Melbourne, Melbourne, Australia, October 26, 2022.
T. Suda, “Proton Radius,” 京都大学物理学科セミナー, 京都大学, 2022 年 12 月 2 日.
K. Tsukada, “Electron scattering from unstable nuclei at SCRIT facility,” GSI NUstar seminar, GSI, Germany, February 13, 2023.
K. Tsukada, “Present status and future prospects of the SCRIT project,” CEA ESNT seminar, CEA-Saclay, France, February 15, 2023.
塚田曉, 「エキゾチックな原子核を造る・観る」, 京都大学丸の内セミナー, 京都大学 東京オフィス (新丸ビル 10 階), 2023 年 3 月
10 日.

Outreach Activity

須田利美, 特別講義「陽子などの物の大きさはどう測る？」, 埼玉県立熊谷高等学校, 2023 年 1 月 21 日.

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Research Facility Development Division
Research Instruments Group
1. Abstract

The Research Instruments Group is the driving force at RI Beam Factory (RIBF) for continuous enhancement of activities andcompetitiveness of experimental research. Consisting of four teams, we are in charge of the operation, maintenance, and improvementof the core research instruments at RIBF, such as the BigRIPS in-ﬂight RI separator, ZeroDegree spectrometer and SAMURAI spectrometer, and the related infrastructure and equipment. We are also in charge of the production and delivery of RI beams using the
BigRIPS separator. The group also conducts related experimental research as well as R&D studies on the research instruments.

2. Major Research Subjects

Design, construction, operation, maintenance, and improvement of the core research instruments at RIBF and related R&D studies.
Experimental studies on exotic nuclei.

3. Summary of Research Activity

The current research subjects are summarized as follows:(1) Production and delivery of RI beams and related research;(2) Design, construction, operation, maintenance, and improvement of the core research instruments at RIBF and their related
infrastructure and equipment;(3) R&D studies on the core research instruments and their related equipment at RIBF;(4) Experimental research on exotic nuclei using the core research instruments at RIBF.

Members
Director
Nobuhisa Fukunishi
Research Consultant
Toshiyuki KUBO
Senior Visiting Scientist
Toshio KOBAYASHI (Tohoku Univ.)
Student Trainees
Fumitaka ENDO (Tohoku Univ.)
Kosuke ICHIMURA (Tohoku Univ.)

Shojiro ISHIO (Tohoku Univ.)

List of Publication
Publication[Original Paper]
D. S. Ahn, J. Amano, H. Baba, N. Fukuda, H. Geissel, N. Inabe, S. Ishikawa, N. Iwasa, T. Komatsubara, T. Kubo, K. Kusa,a, D. J. Morrossey, T. Nakamura, M. Ohtake, H. Otsu, T. Sakakibara, H. Sato, B. M. Sherrill, Y. Shimizu, T. Sumikawa, H. Suzuki, H. Takeda,
O. B. Tarasov, H. Ueno, Y. Yanagisawa, and K. Yoshida, “Discovery of 39 Na,” Phys. Rev. Lett. 129, 215020 (2022). DOI: 10.1103/PhysRevLett.129.212502 .

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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
Senior Research Scientists
Yoshiyuki YANAGISAWA
Naohito INABE

Kensuke KUSAKA
Masao OHTAKETechnical Scientists
Naoki FUKUDA
Yohei SHIMIZU

Hiroshi SUZUKI
Hiroyuki TAKEDA

Contract Researcher
Yasuhiro TOGANO
Postdoctoral Researcher
Masahiro YOSHIMOTO
Visiting Scientists
Deuk Soon AHN (Inst. for Basic Sci.)
Daniel P. BAZIN (Michigan State Univ.)
Hans GEISSEL (GSI)
Naohito IWASA (Tohoku Univ.)

Yutaka MIZOI (Univ. of Electro-Commun.)
Sadao MOMOTA (Kochi Univ. Tech.)David MORRISSEY (Michigan State Univ.)
Oleg TARASOV (Michigan State Univ.)

Student Trainees
Mika EGETA (Tohoku Univ.)

Taiga HAGINOUCHI (Tohoku Univ.)- 312 -

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List of Publications & Presentations
Publications[Original Papers]
M. Duer, T. Aumann, R. Gernhäuser, V. Panin, S. Paschalis, D. M. Rossi, N. L. Achouri, D. Ahn, H. Baba, C. A. Bertulani, M. Böhmer,
K. Boretzky, C. Caesar, N. Chiga, A. Corsi, D. Cortina-Gil, C. A. Douma, F. Dufter, Z. Elekes, J. Feng, B. Fernández-Domı́nguez,
U. Forsberg, N. Fukuda, I. Gasparic, Z. Ge, J. M. Gheller, J. Gibelin, A. Gillibert, K. I. Hahn, Z. Halász, M. N. Harakeh, A. Hirayama,
M. Holl, N. Inabe, T. Isobe, J. Kahlbow, N. Kalantar-Nayestanaki, D. Kim, S. Kim, T. Kobayashi, Y. Kondo, D. Körper, P. Koseoglou,
Y. Kubota, I. Kuti, P. J. Li, C. Lehr, S. Lindberg, Y. Liu, F. M. Marqués, S. Masuoka, M. Matsumoto, J. Mayer, K. Miki, B. Monteagudo,
T. Nakamura, T. Nilsson, A. Obertelli, N. A. Orr, H. Otsu, S. Y. Park, M. Parlog, P. M. Potlog, S. Reichert, A. Revel, A. T. Saito,
M. Sasano, H. Scheit, F. Schindler, S. Shimoura, H. Simon, L. Stuhl, H. Suzuki, D. Symochko, H. Takeda, J. Tanaka, Y. Togano,
T. Tomai, H. T. Törnqvist, J. Tscheuschner, T. Uesaka, V. Wagner, H. Yamada, B. Yang, L. Yang, Z. H. Yang, M. Yasuda, K. Yoneda,
L. Zanetti, J. Zenihiro, and M. V. Zhukov, “Observation of a correlated free four-neutron system,” Nature 606, 678 (2022).
H. F. Li, S. Naimi, T. M. Sprouse, M. R. Mumpower, Y. Abe, Y. Yamaguchi, D. Nagae, F. Suzaki, M. Wakasugi, H. Arakawa, W. B. Dou,
D. Hamakawa, S. Hosoi, Y. Inada, D. Kajiki, T. Kobayashi, M. Sakaue, Y. Yokoda, T. Yamaguchi, R. Kagesawa, D. Kamioka,
T. Moriguchi, M. Mukai, A. Ozawa, S. Ota, N. Kitamura, S. Masuoka, S. Michimasa, H. Baba, N. Fukuda, Y. Shimizu, H. Suzuki,
H. Takeda, D. S. Ahn, M. Wang, C. Y. Fu, Q. Wang, S. Suzuki, Z. Ge, Yu. A. Litvinov, G. Lorusso, P. M. Walker, Zs. Podolyak, andT. Uesaka, “First application of mass measurements with the Rare-RI Ring reveals the solar r-process abundance trend at A = 122 andA = 123,” Phys. Rev. Lett. 128, 152701 (2022).
V. H. Phong, S. Nishimura, G. Lorusso, T. Davinson, A. Estrade, O. Hall, T. Kawano, J. Liu, F. Montes, N. Nishimura, R. Grzywacz,
K. P. Rykaczewski, J. Agramunt, D. S. Ahn, A. Algora, J. M. Allmond, H. Baba, S. Bae, N. T. Brewer, C. G. Bruno, R. Caballero-Folch,
F. Calviño, P. J. Coleman-Smith, G. Cortes, I. Dillmann, C. Domingo-Pardo, A. Fijalkowska, N. Fukuda, S. Go, C. J. Griﬃn, J. Ha,
L. J. Harkness-Brennan, T. Isobe, D. Kahl, L. H. Khiem, G. G. Kiss, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, J. Liang, Z. Liu,
K. Matsui, K. Miernik, B. Moon, A. I. Morales, P. Morrall, N. Nepa, R. D. Page, M. Piersa-Siłkowska, V. F. E. Pucknell, B. C. Rasco,
B. Rubio, H. Sakurai, Y. Shimizu, D. W. Stracener, T. Sumikama, H. Suzuki, J. L. Tain, H. Takeda, A. Tarifeño-Saldivia, A. TolosaDelgado, M. Wolińska-Cichocka, P. J. Woods, and R. Yokoyama, “β-delayed one and two neutron emission probabilities southeast of132
Sn and the odd-even systematics in r-process nuclide abundances,” Phys. Rev. Lett. 129, 172701 (2022).
D. S. Ahn, J. Amano, H. Baba, N. Fukuda, H. Geissel, N. Inabe, S. Ishikawa, N. Iwasa, T. Komatsubara, T. Kubo, K. Kusaka, D. J. Morrissey, T. Nakamura, M. Ohtake, H. Otsu, T. Sakakibara, H. Sato, B. M. Sherrill, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda,
O. B. Tarasov, H. Ueno, Y. Yanagisawa, and K. Yoshida, “Discovery of 39 Na,” Phys. Rev. Lett. 129, 212502 (2022).
A. Vitéz-Sveiczer, A. Algora, A. I. Morales, B. Rubio, G. G. Kiss, P. Sarriguren, P. Van Isacker, G. de Angelis, F. Recchia, S. Nishimura,
J. Agramunt, V. Guadilla, A. Montaner-Pizá, S. E. A. Orrigo, A. Horváth, D. Napoli, S. Lenzi, A. Boso, V. H. Phong, J. Wu, P. A. Söderström, T. Sumikama, H. Suzuki, H. Takeda, D. S. Ahn, H. Baba, P. Doornebal, N. Fukuda, N. Inabe, T. Isobe, T. Kubo,
S. Kubono, H. Sakurai, Y. Shimizu, C. Sidong, B. Blank, P. Ascher, M. Gerbaux, T. Goigoux, J. Giovinazzo, S. Grévy, T. KurtukiánNieto, C. Magron, W. Gelletly, Zs. Dombrádi, Y. Fujita, M. Tanaka, P. Aguilera, F. Molina, J. Eberth, F. Diel, D. Lubos, C. Borcea,
E. Ganioglu, D. Nishimura, H. Oikawa, Y. Takei, S. Yagi, W. Korten, G. de France, P. Davies, J. Liu, J. Lee, T. Lokotko, I. Kojouharov,
N. Kurz, H. Shaﬀner, and A. Petrovici, “The β-decay of 70 Kr into 70 Br: Restoration of the pseudo-SU(4) symmetry,” Phys. Lett. B 830,
137123 (2022).
S. Kim, J. W. Hwang, Y. Satou, N. A. Orr, T. Nakamura, Y. Kondo, J. Gibelin, N. L. Achouri, T. Aumann, H. Baba, F. Delaunay, P. Doornenbal, N. Fukuda, N. Inabe, T. Isobe, D. Kameda, D. Kanno, N. Kobayashi, T. Kobayashi, T. Kubo, S. Leblond, J. Lee, F. M. Marqués,
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. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, Y. Togano, A. G. Tuﬀ, M. Vandebrouck, andK. Yoneda, “Unbound states in 17 C and p-sd shell-model interactions,” Phys. Lett. B 836, 137629 (2022).
B. Moon, A. Gargano, H. Naı̈dja, C. -B. Moon, A. Odahara, R. Lozeva, S. Nishimura, C. Yuan, F. Browne, P. Doornenbal, G. Lorusso,
Z. Patel, S. Rice, M. Si, L. Sinclair, P. -A. Söderström, T. Sumikama, H. Watanabe, J. Wu, Z. Y. Xu, A. Yagi, D. S. Ahn, H. Baba,
F. L. Bello Garrote, R. Daido, J. M. Daugas, F. Didierjean, Y. Fang, N. Fukuda, B. Hong, E. Ideguchi, N. Inabe, T. Ishigaki, T. Isobe,
H. S. Jung, D. Kameda, I. Kojouharov, T. Komatsubara, T. Kubo, Y. K. Kwon, C. S. Lee, P. Lee, S. Morimoto, D. Murai, M. Niikura,
H. Nishibata, I. Nishizuka, H. Sakurai, Y. Shimizu, H. Suzuki, H. Takeda, K. Tshoo, and R. Yokoyama, “First observation of theπ0h11/2 ⊗ ν0h9/2 partner orbital conﬁguration in the odd-odd 138 I nucleus,” Phys. Rev. C 105, 034334 (2022).
A. Yagi, A. Odahara, H. Nishibata, R. Lozeva, C. -B. Moon, S. Nishimura, K. Yoshida, N. Yoshinaga, C. Watanabe, K. Higashiyama,
T. Shimoda, R. Daido, Y. Fang, P. S. Lee, B. Moon, P. Doornenbal, G. Lorusso, P. -A. Söderström, T. Sumikama, H. Watanabe, T. Isobe,
H. Baba, H. Sakurai, F. Browne, Z. Patel, S. Rice, L. Sinclair, J. Wu, Z. Y. Xu, R. Yokoyama, T. Kubo, N. Inabe, H. Suzuki, N. Fukuda,
D. Kameda, H. Takeda, D. S. Ahn, Y. Shimizu, D. Murai, F. L. Bello Garrote, J. -M. Daugas, F. Didierjean, E. Ideguchi, S. Iimura,
T. Ishigaki, H. S. Jung, T. Komatsubara, Y. K. Kwon, C. S. Lee, S. Morimoto, M. Niikura, I. Nishizuka, and K. Tshoo, “Various nuclear
structures in 140 Xe studied by β decay of ground and isomeric states in 140 I,” Phys. Rev. C 105, 044325 (2022).
M. Tanaka, M. Takechi, A. Homma, A. Prochazka, M. Fukuda, D. Nishimura, T. Suzuki, T. Moriguchi, D. S. Ahn, A. Aimaganbetov, M. Amano, H. Arakawa, S. Bagchi, K. -H. Behr, N. Burtebayev, K. Chikaato, H. Du, T. Fujii, N. Fukuda, H. Geissel, T. Hori,
S. Hoshino, R. Igosawa, A. Ikeda, N. Inabe, K. Inomata, K. Itahashi, T. Izumikawa, D. Kamioka, N. Kanda, I. Kato, I. Kenzhina,
Z. Korkulu, Y. Kuk, K. Kusaka, K. Matsuta, M. Mihara, E. Miyata, D. Nagae, S. Nakamura, M. Nassurlla, K. Nishimuro, K. Nishizuka,
K. Ohnishi, M. Ohtake, T. Ohtsubo, S. Omika, H. J. Ong, A. Ozawa, H. Sakurai, C. Scheidenberger, Y. Shimizu, T. Sugihara,
T. Sumikama, H. Suzuki, S. Suzuki, H. Takeda, Y. Tanaka, Y. K. Tanaka, I. Tanihata, T. Wada, K. Wakayama, S. Yagi, T. Yamaguchi, R. Yanagihara, Y. Yanagisawa, K. Yoshida, and T. K. Zholdybayev, “Charge-changing cross sections for 42–51 Ca and eﬀect ofcharged-particle evaporation induced by neutron-removal reactions,” Phys. Rev. C 106, 014617 (2022).

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J. Wu, S. Nishimura, P. -A. Söderström, A. Algora, J. J. Liu, V. H. Phong, Y. Q. Wu, F. R. Xu, J. Agramunt, D. S. Ahn, T. A. Berry,
C. G. Bruno, J. J. Bundgaard, R. Caballero-Folch, A. C. Dai, T. Davinson, I. Dillmann, A. Estrade, A. Fijałkowska, N. Fukuda, S. Go,
R. K. Grzywacz, T. Isobe, S. Kubono, G. Lorusso, K. Matsui, A. I. Morales, N. Nepal, S. E. A. Orrigo, B. C. Rasco, K. P. Rykaczewski,
H. Sakurai, Y. Shimizu, D. W. Stracener, T. Sumikama, H. Suzuki, J. L. Tain, H. Takeda, A. Tarifeño-Saldivia, A. Tolosa-Delgado,
M. Wolinska-Cichocka, and R. Yokoyama, “First observation of isomeric states in 111 Zr, 113 Nb, and 115 Mo,” Phys. Rev. C 106, 064328(2022).
J. W. Lee, M. B. Tsang, C. Y. Tsang, R. Wang, J. Barney, J. Estee, T. Isobe, M. Kaneko, M. Kurata-Nishimura, W. G. Lynch, T. Murakami,
A. Ono, S. R. Souza, D. S. Ahn, L. Atar, T. Aumann, H. Baba, K. Boretzky, J. Brzychczyk, G. Cerizza, N. Chiga, N. Fukuda, I. Gasparic,
B. Hong, A. Horvat, K. Ieki, N. Ikeno, N. Inabe, G. Jhang, Y. J. Kim, T. Kobayashi, Y. Kondo, P. Lasko, H. S. Lee, Y. Leifels, J. Łukasik,
J. Manfredi, A. B. McIntosh, P. Morfouace, T. Nakamura, N. Nakatsuka, S. Nishimura, H. Otsu, P. Pawłowski, K. Pelczar, D. Rossi,
H. Sakurai, C. Santamaria, H. Sato, H. Scheit, R. Shane, Y. Shimizu, H. Simon, A. Snoch, A. Sochocka, T. Sumikama, H. Suzuki,
D. Suzuki, H. Takeda, S. Tangwancharoen, Y. Togano, Z. G. Xiao, S. J. Yennello, and Y. Zhang (the SπRIT Collaboration), “Isoscaling
in central Sn+Sn collisions at 270 MeV/nucleon,” Eur. Phys. J. A 58, 201 (2022).
A. I. Stefanescu, V. Panin, L. Trache, T. Motobayashi, H. Otsu, A. Saastamoinen, T. Uesaka, L. Stuhl, J. Tanaka, D. Tudor, I. C. Stefanescu,
A. E. Spiridon, K. Yoneda, H. Baba, M. Kurokawa, Y. Togano, Z. Halasz, M. Sasano, S. Ota, Y. Kubota, D. S. Ahn, T. Kobayashi,
Z. Elekes, N. Fukuda, H. Takeda, D. Kim, E. Takada, H. Suzuki, K. Yoshida, Y. Shimizu, H. N. Liu, Y. L. Sun, T. Isobe, J. Gibelin,
P. J. Li, J. Zenihiro, F. M. Marqués, M. N. Harakeh, G. G. Kiss, A. Kurihara, M. Yasuda, T. Nakamura, S. Park, Z. Yang, T. Harada,
M. Nishimura, H. Sato, I. S. Hahn, K. Y. Chae, J. M. Elson, L. G. Sobotka and C. A. Bertulani, “Silicon tracker array for RIB
experiments at SAMURAI,” Eur. Phys. J. A 58, 223 (2022).
G. G. Kiss, A. Vitéz-Sveiczer, Y. Saito, A. Tarifeño-Saldivia, M. Pallas, J. L. Tain, I. Dillmann, J. Agramunt, A. Algora, C. DomingoPardo, A. Estrade, C. Appleton, J. M. Allmond, P. Aguilera, H. Baba, N. T. Brewer, C. Bruno, R. Caballero-Folch, F. Calvino,
P. J. Coleman-Smith, G. Cortes, T. Davinson, N. Fukuda, Z. Ge, S. Go, C. J. Griﬃn, R. K. Grzywacz, O. Hall, A. Horváth, J. Ha,
L. J. Harkness-Brennan, T. Isobe, D. Kahl, T. T. King, A. Korgul, S. Kovács, R. Krücken, S. Kubono, M. Labiche, J. Liu, J. Liang,
M. Madurga, K. Miernik, F. Molina, A. I. Morales, M. R. Mumpower, E. Nacher, A. Navarro, N. Nepal, S. Nishimura, M. PiersaSiłkowska, V. Phong, B. C. Rasco, B. Rubio, K. P. Rykaczewski, J. Romero-Barrientos, H. Sakurai, L. Sexton, Y. Shimizu, M. Singh,
T. Sprouse, T. Sumikama, R. Surman, H. Suzuki, T. N. Szegedi, H. Takeda, A. Tolosa, K. Wang, M. Wolinska-Cichocka, P. Woods,
R. Yokoyama, and Z. Xu, “Measuring the β-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the
nucleosynthesis yields in the rare-earth region,” Astrophys. J. 936, 107 (2022).

[Proceeding]
S. Kim, J. Hwang, Y. Satou, N. A. Orr, T. Nakamura, Y. Kondo, J. Gibelin, N. L. Achouri, T. Aumann, H. Baba, F. Delaunay, P. Doornenbal, N. Fukuda, N. Inabe, T. Isobe, D. Kameda, D. Kanno, N. Kobayashi, T. Kobayashi, T. Kubo, S. Leblond, J. Lee, F. M. Marqués,
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. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, Y. Togano, A. G. Tuﬀ, M. Vandebrouck, andK. Yoneda, “Spectroscopy of 17 C above the neutron separation energy,” Few-Body Syst. 63, 21 (2022).

Presentations[International Conferences/Workshops]
H. Suzuki (invited), “Studies of the two-step scheme with a 132 Sn beam for next-generation RI-beam production in the medium-heavy veryneutron-rich region,” The 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS), Daejeon,
Korea, October 3–7, 2022.
M. Yoshimoto (oral), N. Fukuda, H. Otsu, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda, J. Tanaka, K. Yoshida, R. Matsumura,
D. Nishimura, and H. Takahashi, “Development of new ionization chamber specialized in high-Z beam,” The 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS), Daejeon, Korea, October 3–7, 2022.
K. Yoshida (oral), Y. Yanagisawa, M. Ohtake, and T. Kubo, “Operational experiences of high-power production target and high-power
beam dump at BigRIPS separator at RIKEN RI beam factory,” The 19th International Conference on Electromagnetic Isotope Separators
and Related Topics (EMIS), Daejeon, Korea, October 3–7, 2022.

[Domestic Conferences/Workshops]

金子雅紀 (口頭発表), 村上哲也, 磯部忠昭, 倉田 (西村) 美月, 小野章, 池野なつ美, J. Barney, G. Cerizza, J. Estee, G. Jhang, J. W. Lee,W. G. Lynch, C. Santamaria, C. Y. Tsang, M. B. Tsang, R. Wang, D. S. Ahn, G, L. Atar, H, T. Aumann, 馬場秀忠, K. Boretzky,
J. Brzychczyk, 千賀信幸, 福田直樹, I. Gašparić, B. Hong, A. Horvat, 市原卓, 家城和夫, 稲辺尚人, Y. J. Kim, 小林俊雄, 近藤洋介,
P. Lasko, H. S. Lee, Y. Leifels, J. Łukasik, J. Manfredi, A. B. McIntosh, P. Morfouace, 中村隆司, 中塚徳継, 西村俊二, R. Olsen, 大津
秀暁, P. Pawłowski, K. Pelczar, D. Rossi, 櫻井博儀, 佐藤広海, H. Scheit, R. Shane, 清水陽平, H. Simon, 炭竃聡之, 鈴木大介, 鈴木宏, 竹田浩之, S. Tangwancharoen, 栂野康宏, H. Törnqvist, H, Z. Xiao, S. J. Yennello, J. Yurkon, Y. Zhang, 「RI ビームを用いた重イオン衝突における水素同位体生成と高密度核物質の対称エネルギー」, 日本物理学会第 77 回年次大会 (2022 年), オンライン,
2022 年 3 月 15–19 日.
篠原悠介 (口頭発表), 市川雄一, 郷慎太郎, 西畑洸希, 安藤蒼太, 荒殿和希, 旭耕一郎, 馬場秀忠, 福田直樹, G. Georgiev, A. Gladkov,
今村慧, 梶原孝文, 岸本侃己, R. Lozeva, 向井もも, 新倉潤, M. N. Nurhaﬁza, 小田原厚子, 清水陽平, M. Si, C, K. Stoychev, 鈴木宏, 立川柊平, 田島美典, 高峰愛子, 竹田浩之, 竹中京平, 武重祥子, 上野秀樹, 若狭智嗣, 山下渉, 山崎展樹, 横田望海, 吉本雅浩,
J. M. Daugas, 「分散整合二回散乱法による 99 Zr アイソマー状態のスピン整列」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
H. Lee(oral), T. Nakamura, N. Nakatsuka, A, Y. Kondo, K. J. Cook, S. Ogoshi, A. T. Saito, N. L. Achouri, T. Aumann, E, H. Baba,
F. Delaunay, Q. Deshayes, P. Doornenbal, N. Fukuda, J. Gibelin, J. W. Hwang, N. Inabe, T. Isobe, D. Kameda, D. Kanno, S. Kim,

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N. Kobayashi, T. Kobayashi, T. Kubo, S. Leblond, J. Lee, F. M. Marques, R. Minakata, T. Motobayashi, K. Muto, T. Murakami,
D. Murai, T. Nakashima, A. Navin, S. Nishi, N. A. Orr, H. Otsu, H. Sato, Y. Satou, Y. Shimizu, H. Suzuki, K. Takahashi, H. Takeda,
S. Takeuchi, R. Tanaka, Y. Togano, J. Tsubota, A. G. Tuﬀ, M. Vandebrouck, and K. Yoneda, “Coulomb dissociation of 17 B,” 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.

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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, amount numbers of experiments were
well performed until now utilizing the property of SAMURAI. The team also provides a basis for research activities by, for example,
organizing collaboration workshops by researchers who are interested in studies or plan to perform experiments with the SAMURAI
spectrometer.

2. Major Research Subjects

Design, operation, maintenance and improvement of the SAMURAI spectrometer and its related research instruments. Supportand management for SAMURAI-based research programs. Generate future plans for next generation instruments for nuclear reaction
studies.

3. Summary of Research Activity

The current research subjects are summarized as follows:(1) Operation, maintenance and improvement of a large superconducting dipole magnet, the main component of the SAMURAI
spectrometer(2) Design, development and construction of various detectors that are used for nuclear reaction experiments using the SAMURAI
spectrometer(3) Preparation for planning experiments using SAMURAI spectrometer(4) Maintenance and improvement of the SAMURAI beam line
(5) Formation of a collaboration platform called “SAMURAI collaboration”(6) Preparation for next generation spectrometer for nuclear reaction studies

Members
Team Leader
Hideaki OTSU
Research & Development Scientist
Mizuki NISHIMURA

List of Publications & Presentations
Publications[Original Papers]
T. Phol et al., “Multiple mechanisms in proton-induced nucleon removal at 100 MeV/nucleon,” Phys. Rev. Lett. 130,172501 (2023).
A. Corsi et al., “Searching for universality of dineutron correlation at the surface of Borromean nuclei,” Phys. Lett. B 840, 137875 (2023).
S. Kim et al., “Unbound states in 17 C and p-sd shell-model interactions,” Phys. Lett. B 836, 137629 (2023).
A. I. Stefanescu et al., “Silicon tracker array for RIB experiments at SAMURAI,” Eur. Phys. J. A 58, 223 (2022).
M. Kaneko et al., “Multiplicity trigger detector for the SπRIT experiment,” Nucl. Instrum. Methods Phys. Res. A 1039, 167010 (2022).
M. Enciu et al., “Extended p3/2 neutron orbital and the N = 32 shell closure in 52 Ca,” Phys. Rev. Lett. 129, 262501 (2022).
Z. Elekes et al., “Southwestern boundary of the N = 40 island of inversion: First study of low-lying bound excited states in 59 V and 61 V,”
Phys. Rev. C 106, 064321 (2022).
J. W. Lee et al., “Isoscaling in central Sn+Sn collisions at 270 MeV/nucleon,” Eur. Phys. J. A 58, 201 (2022).
M. Duer et al., “Observation of a correlated four-neutron system,” Nature 606, 678–682 (2022).
M. Holl et al., “Border of the island of inversion: Unbound states in 29 Ne,” Phys. Rev. C 105, 034301 (2022).
T. Koiwai et al., “A ﬁrst glimpse at the shell structure beyond 54 Ca: Spectroscopy of 55 K, 55 Ca, and 57 Ca,” Phys. Lett. B 827, 136953(2022).

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Presentations[International Conferences/Workshops]
SAMURAI International Collaboration Workshop 2022, Tokyo Institute of Technology, Tokyo & Online, September 2–3, 2022.
https://indico2.riken.jp/event/4219/ .
T. Nakamura (invited), “Spectroscopy of nuclei near and beyond the neutron dripline,” ECT* Workshop on “Nuclear Physics at the Edgeof Stability,” Online & Trento, Italy (Hybrid), July 4–8, 2022.
T. Nakamura (plenary/invited), “Summary Talk,” The 11th International Conference on Direct Reactions with Exotic Beams (DREB2022),
Santiago de Compostela, Spain, June 26–July 1, 2022.
Y. Kondo (invited), “Experimental studies near and beyond the dripline at SAMURAI,” Halo Week 2022, Bergen, Norway (Grand Hotel
Terminus), July 10–15, 2022.
Y. Kondo (invited), “Experimental studies of nuclei in the vicinity of the neutron-drip line at SAMURAI,” Physics of RI: Recent progress
and perspectives, RIKEN, Saitama, Japan, May 30–June 1, 2022.

[Domestic Conferences/Workshops]

久保田悠樹 (招待講演), 若手奨励賞講演, 「11 Li 原子核中でのダイニュートロンの表面局在」, 日本物理学会春季大会, オンライン,
2023 年 3 月.
松井智輝, 「中性子過剰 He 同位体における多中性子系クラスターの探索」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3月.
H. Lee, “Coulomb Dissociation of 17 B,” 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月.
磯部駆, 「中性子過剰核における短距離相関対探索のための後方散乱粒子検出器の開発」, 日本物理学会秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月.
松井智輝, 「多中性子クラスター探索実験に向けた反跳陽子検出器のテスト実験」, 日本物理学会秋季大会, 岡山市 (岡山理科大学),
2022 年 9 月.

Press Release“Observation of a correlated free four-neutron system,” June 23, 2022, https://www.riken.jp/press/2022/20220623_1/index.
html .

Master Theses

堀川晃太, 「中性子過剰核における短距離相関探索実験」, 東京工業大学, 2023 年 2 月.
松井智輝, 「中性子過剰 He 同位体における多中性子クラスターの探索」, 東京工業大学, 2023 年 2 月.

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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 services 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 services and data acquisition system and management of the information security of the RIKEN Nishina Center.The details aredescribed elsewhere in this progress report.
(1) Development, management and operation of the general computing servers
We are operating Linux cluster system for the data analysis of the experiments and general computing. This cluster system consistsof eight computing servers with 74 CPU cores and totally 500 TB RAID of highly-reliable Fibre-channel interconnection. There areapproximately 100 active user accounts on this cluster system. We are adopting the latest version of the Linux operating system.
In addition to the cluster system, we have constructed analysis environment on the private could system of HOKUSAI Sailing Ship
operated by Information Systems Division in RIKEN. As computational resources for data analysis of RIBF experiments, 80 core and
150 TB diskspace are reserved. These resources are dynamically allocated to several experimental projects.
(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 enablesecure and reliable mail delivery. We are operating several information servers such as Web servers, Integrated Digital Conference(INDICO) server, Wiki servers, Groupware servers, Wowza streaming servers.
(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 other 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. To improve the data readout speed of VME system,
we have successfully developed the MPV system which is a parallel readout extension of the VME system. Thanks to the MPV
system, now the DAQ system in RIBF is 10 times faster than in 2007. Toward to the next generation DAQ system, we have started
to develop a real-time data processing unit based on Xilinx RFSoC that includes FPGA and 4 GHz FADC for TOF measurements ofplastic scintillators. For gaseous detectors like PPAC and drift chamber, the development of FPGA-based dead-time free TDC is now
in progress. For Silicon semiconductor detectors, waveform digitizer based front-end electronics is commissioned. From 2022, Signal
processing and data acquisition infrastructure (SPADI) alliance is launched to advance collaborative DAQ development in Japanese
nuclear physics community. This team participates as one of the core members of the SPADI alliance.
(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 bps). In addition, some 10 Gbps
networks port has been introduced to RIBF experimental area. We have been operating approximately 70 units of wireless LAN accesspoints in RNC. Almost the entire radiation-controlled area of the East Area of RIKEN Wako campus is covered by wireless LAN for
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RIKEN Information Systems Division is additionally introduced in the measurement rooms in RIBF B1F and B3F.
(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
Junior Research Associate
Shoko TAKESHIGE (Rikkyo Univ.)
Special Temporary Research Scientists
Takashi ICHIHARA

Yasushi WATANABE

Visiting Scientists
Kazuo IEKI (Rikkyo Univ.)

Shoichiro KAWASE (Kyushu Univ.)

Student Trainee
Shoko TAKESHIGE (Rikkyo Univ.)

List of Presentations
Presentations[International Conference/Workshop]
S. Takeshige, H. Baba et al. (poster), “Time determination method using digital waveform processing with RFSoC for RI beam experiments,” 23rd Virtual IEEE Real Time Conference, Online, August 1–5, 2022.

[Domestic Conference/Workshop]

馬場秀忠 (口頭発表), 「WG2（時刻同期・通信）報告と展望」, 原子核実験の先端データ収集システム—標準化と将来—, 茨木市 (大阪大学 RCNP), 2022 年 5 月 17 日.

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Research Facility Development Division
Research Instruments Group
Detector Team
1. Abstract

This team is in charge of 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 beam-line detectors which are used for the production and delivery of RI beams (beamdiagnosis 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)
Student Trainees
Kotoko INAYOSHI (Toho University)
Mai KURINO (Toho University)

Ryusei OTANI (Toho University)

List of Publications & Presentations
Publications[Original Papers]
S. R. Lee, A. Kim, S. Choi, T. Ikeda, T. Isoshima, S. Cho, and Y. Kim, “Amorphous to polycrystalline phase transition in La2 O3 ﬁlms
grown on a silicon substrate forming Si-doped La2 O3 ﬁlms,” Phys. Status Solidi 219, 2200318 (2022).
D. S. Ahn, J. Amano, H. Baba, N. Fukuda, H. Geissel, N. Inabe, S. Ishikawa, N. Iwasa, T. Komatsubara, T. Kubo, K. Kusaka, D. J. Morrissey, T. Nakamura, M. Ohtake, H. Otsu, T. Sakakibara, H. Sato, B. M. Sherrill, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda,
O. B. Tarasov, H. Ueno, Y. Yanagisawa, and K. Yoshida, “Discovery of 39 Na,” Phys. Rev. Lett. 129, 212502 (2022).
A. I. Stefanescu, V. Panin, L. Trache, T. Motobayashi, H. Otsu, A. Saastamoinen, T. Uesaka, L. Stuh, J. Tanaka, D. Tudor, I. C. Stefanescu,
A. E. Spiridon, K. Yoneda, H. Baba, M. Kurokawa, Y. Togano, Z. Halasz, M. Sasano, S. Ota, Y. Kubota, D. S. Ahn, T. Kobayashi,
Z. Elekes, N. Fukuda, H. Takeda, D. Kim, E. Takada, H. Suzuki, K. Yoshida, Y. Shimizu, H. N. Liu, Y. L. Sun, T. Isobe, J. Gibelin,
P. J. Li, J. Zenihiro, F. M. Marqués, M. N. Harakeh, G. G. Kiss, A. Kurihara, M. Yasuda, T. Nakamura, S. Park, Z. Yang, T. Harada,
M. Nishimura, H. Sato, I. S. Hahn, K. Y. Chae, J. M. Elson, L. G. Sobotka, and C. A. Bertulani, “Silicon tracker array for RIB
experiments at SAMURAI,” Eur. Phys. J. A 58, 223 (2022).
S. Kim, J. W. Hwang, Y. Satou, N. A. Orr, T. Nakamura, Y. Kondo, J. Gibelin, N. L. Achouri, T. Aumann, H. Baba, F. Delaunay, P. Doornenbal, N. Fukuda, N. Inabe, T. Isobe, D. Kameda, D.Kanno, N. Kobayashi, T. Kobayashi, T. Kubo, S. Leblond, J. Lee, F. M. Marqués,
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. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, Y. Togano, A. G. Tuﬀ, M. Vandebrouck, andK. Yoneda, “Unbound states in 17 C and p-sd shell-model interactions,” Phys. Lett. B 836, 137629 (2023).

[Review Articles]

池田時浩, 「MeV イオンビームのガラスキャピラリーによるマイクロビーム化とその応用」, 応用物理 91, 542–647 (2022).
T. Ikeda, “Production of MeV ion microbeams using glass capillary optics and its applications,” JSAP Review 2022, 220205 (2022).

Presentations[International Conferences/Workshops]
K. Inayoshi (poster), T. Ikeda, K. Ono, and W. -G. Jin, “Density enhancement of ion microbeams with miniature quadrupole magnets fortapered glass capillary opticss,” ICACS & SHIM 2022, Helsinki, Finland & Online, June 19–24, 2022.

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T. Ikeda (oral), “Glass capillary optics as an ion microbeam generator and its applications,” 2nd Annual Meeting of MRS-Japan 2022,
Yokohama, Japan, December 5–7, 2022.

[Domestic Conferences/Workshops]

稲吉琴子 (口頭発表), 池田時浩, 金衛国, 「小型四重極永久磁石を用いたガラスキャピリー内のイオンビームの通過特性の研究」,第34 回タンデム加速器及びその周辺技術の研究会, オンライン, 2022 年 7 月 21–22 日.
水野るり惠 (口頭発表), 池田時浩, 郷慎太郎, 櫻井博儀, 齋藤岳志, 新倉潤, 松崎禎市郎, 道正新一郎, 「1 MeV 陽子ビームを用いた広ダイナミックレンジ光子検出器の性能評価実験」, 第 34 回タンデム加速器及びその周辺技術の研究会, オンライン, 2022 年 7 月
21–22 日.
池田時浩 (口頭発表), 稲吉琴子, 佐藤広海, 「理化学研究所におけるタンデム加速器の現状（2020–2021 年度）」
, 第 34 回タンデム加速器及びその周辺技術の研究会, オンライン, 2022 年 7 月 21–22 日.
稲吉琴子 (ポスター発表), 池田時浩, 金衛国, 「小型四重極永久磁石によるビーム拡がり抑制のキャピラリーマイクロビームへの応用」, 原子衝突学会 第 47 回年会, 宮崎市 (宮崎大学), 2022 年 9 月 8–9 日.
池田時浩 (ポスター発表), 「絶縁体キャピラリーによるイオンビームガイディング: 20 年の歩み」, 原子衝突学会 第 47 回年会, 宮
崎市 (宮崎大学), 2022 年 9 月 8–9 日.
水野るり惠 (口頭発表), 池田時浩, 郷慎太郎, 齋藤岳志, 櫻井博儀, 新倉潤, 松崎禎市郎, 道正新一郎, 「Ge 検出器を用いた光子検出器システムの広ダイナミックレンジにおける性能評価実験」, 第 65 回放射線化学討論会, オンライン, 2022 年 9 月 10–12 日.
稲吉琴子 (口頭発表), 池田時浩, 金衛国, 「ガラスキャピラリー内部のイオンビーム軌道制御のための小型四重極永久磁石の作製」,
日本物理学会 2022 年秋季大会, 目黒区 (東京工業大学), 2022 年 9 月 12–15 日.
稲吉琴子 (ポスター発表), 池田時浩, 金衛国, 「キャピラリー内イオン衝突抑制のための小型四重極永久磁石の作製」, 第 42 回 原子
衝突若手の会 秋の学校, 高崎市 (榛名湖温泉ゆうすげ), 2022 年 10 月 8–10 日.

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Accelerator Applications Research Division
Beam Mutagenesis Group
1. Abstract

This group promotes biological applications of ion beams from RI Beam Factory (RIBF). Ion Beam Breeding Team studies
various biological eﬀects of fast heavy ions and develops new technology to breed plants and microbes by heavy-ion irradiations.
Plant Genome Evolution Research Team choose baker’s yeast and the legume Lotus japonicus as model systems to characterize
genomic mutations using the population genomics approach with robust molecular biology and bioinformatics techniques.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Biological eﬀects of fast heavy ions
Molecular nature of DNA alterations induced by heavy-ion irradiation
Research and development of heavy-ion breeding
Genomics-based approach to revolutionize the mutagenesis in plants and microbes

3. Summary of Research Activity

Summary of research activities of the two teams are given in the sections of each team.

Members
Director
Tomoko ABE
Senior Visiting Scientist
Yutaka ARIMOTO- 323 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Accelerator Applications Research Division
Beam Mutagenesis GroupIon Beam Breeding Team
1. Abstract

Ion beam breeding team studies various biological eﬀects of fast heavy ions. It also develops new technique to breed plants andmicrobes by heavy-ion irradiations. Fast heavy ions can produce dense and localized ionizations in matters along their tracks, incontrast to photons (X rays and gamma rays) which produce randomly distributed isolated ionizations. These localized and dense
ionization can cause double-strand breaks of DNA which are not easily repaired and result in mutation more eﬀectively than singlestrand breaks. A unique feature of our experimental facility at the RIKEN Ring Cyclotron (RRC) is that we can irradiate living
tissues in atmosphere since the delivered heavy-ion beams have energies high enough to penetrate deep in matter. This team utilizes adedicated beam line (E5B) of the RRC to irradiate microbes, plants and animals with beams ranging from carbon to iron. Its researchsubjects cover study of ion-beam radiation mutagenesis, genome-wide analyses of mutation, and development of new plants andmicrobial varieties by heavy-ion irradiation. Thirty-nine new varieties have already been brought to the market.

2. Major Research Subjects(1) Study on the biological eﬀects by heavy-ion irradiation(2) Study on the molecular nature of DNA alterations induced by heavy-ion irradiation(3) Innovative applications of heavy-ion irradiation

3. Summary of Research Activity

We study biological eﬀects of fast heavy ions from the RRC using 135 MeV/nucleon C, N, Ne ions, 95 MeV/nucleon Ar ions,
90 MeV/nucleon Fe ions and from the IRC using 160 MeV/nucleon Ar ions. We also develop breeding technology of microbes andplants. Main subjects are:(1) Study on the biological eﬀects by heavy-ion irradiation
Heavy-ion beam deposits a concentrated amount of dose at just before stop with severely changing the linear energy transfer(LET). The peak of LET is achieved at the stopping point and known at the Bragg peak (BP). Adjusting the BP to target malignant
cells is well known to be eﬀective for cancer therapy. On the other hand, a uniform dose distribution is a key to the systematic study
for heavy-ion mutagenesis, thus to the improvement of the mutation eﬃciency. Plants and microbes therefore, are irradiated using ionswith stable LET. We investigated the eﬀect of LET ranging from 23 to 640 keV/µm, on mutation induction using dry seeds of the model
plants Arabidopsis thaliana and rice (Oryza sativa L.). The most eﬀective LET (LETmax) was 30 keV/µm in Arabidopsis. LETmax
irradiations showed the same mutation rate as that by chemical mutagens, which typically cause high mutation rate. The LETmax
was 23–39 keV/µm in buckwheat, 23–50 keV/µm in rice and 50–70 keV/µm in wheat. By contrast, when LET was 290 keV/µm, themutation rate was low and the survival rate was greatly reduced in plants. In the case of microbe, ﬁlamentous fungus (Neurospora
crassa), the Ar ions at 290 keV/µm demonstrated higher mutagenic activity than the Fe-ions at 640 keV/µm. Thus, the LET is an
important factor to be considered in heavy-ion mutagenesis.
(2) Study on the molecular nature of DNA alterations induced by heavy-ion irradiation
A whole-genome analysis with high-throughput sequencing is a powerful tool used to characterize the nature of induced mutations.
We have been using whole genome sequencing to analyze DNA mutations in Arabidopsis and rice genomes. C ions with LETmax
mainly induced single nucleotide variants (SNVs) and small insertions and deletions (InDels), while the number of large deletions
and chromosomal rearrangements was low in Arabidopsis. However, 290 keV/µm Ar ions showed a diﬀerent mutation spectrum:
SNVs and number of small InDels was low, while the number of large deletions (≥100 bp) and chromosomal rearrangements washigh. Number of mutated gene induced by C-ion and Ar-ion irradiation is less than 10, relatively small, and often only 1 mutation isfound near the mapped location. Thus, irradiation with these ions can eﬃciently generate knockout mutants of a target gene and canbe applied to reverse genetics. Rice mutants of the causative gene induced by ion-beam irradiation were compared at 23–50 keV/µm
and 290 keV/µm with typical LETs. The most mutations irradiated with C ion at 23–50 keV/µm were small deletions (<100 bp).
Irradiation with 290 keV/µm Ar-ion resulted in the highest number of large deletions and decreased small deletions. In rice, as in
Arabidopsis, the LETmax with high mutagenic eﬀects was dominated by SNVs and small deletion mutations, while large deletions
and chromosomal rearrangement mutations dominated LETs with high lethal eﬀects.
(3) Innovative application of heavy-ion irradiation
In 1999, we formed a consortium for ion-beam breeding consisting of 24 groups. In 2022, the consortium grew to 184 groups
from Japan and 22 from overseas. Previously, the ion-beam breeding procedures were carried out using mainly ﬂowers and ornamental
plants. We have recently put a new non-pungent and tearless onion, ‘Smile Ball,’ on the market along with ‘Kiku Meigetsu,’ anedible late ﬂowering chrysanthemum. In addition, a new project was launched to expand the cultivation area of this variety ofchrysanthemum in Yamagata prefecture. Beneﬁcial variants have been grown for various plant species, such as high yield sea weeds,
lipids hyperaccumulating unicellular alga, medicinal plant with high productivity of medicinal ingredient, peanuts without major
allergens, oranges with delayed coloring and one-month late harvest, and lettuce with a low browning property as a cut vegetable. As- 324 -

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a result of a collaborative study with Shizuoka prefecture, we have created a new variety of ‘Haru Shizuka,’ which is late coloring.
The harvest time of the Satsuma mandarin has tended to come earlier due to global warming, ‘Haru Shizuka’ is harvested about amonth later than the original variety, but the fruits are sour when harvested. ‘Haru Shizuka’ is suitable for long-term storage and thefruits turn into good quality sweet oranges during storage till April. By broadening the target of heavy-ion breeding extending fromﬂowers to crops, the technology will contribute to solving the global problems of food shortage and environmental destruction.

Members
Team Leader
Tomoko ABE
Research/Technical Scientists
Tokihiro IKEDA (Senior Research Scientist)
Masako IZUMI (Senior Research Scientist)
Ryouhei MORITA (Technical Scientist)

Teruyo TSUKADA (Senior Research Scientist)
Kazuhide TSUNEIZUMI (Senior Research Scientist)

Postdoctoral Researcher
Asanga D. N. IMIHAMI MUDIYANSELAGE
Technical Staﬀs
Yoriko HAYASHI
Yuki SHIRAKAWA

Sumie OHBU
Mieko YAMADASpecial Temporary Technical Scientists
Hiroshi ABE

Katsunori ICHINOSE

Research Consultant
Masahiro MII (Chiba Univ.)
Visiting Scientists
Tory CHHUN (Prek Leap Nat’l Inst. of Agriculture)
Ayumi DEGUCHI (Chiba Univ.)
Makoto FUJIWARA (Sophia Univ.)
Eitaro FUKATSU (Forestry and Forest Products Res. Inst.)
Tomonari HIRANO (Univ. of Miyazaki)
Akiko HOKURA (Tokyo Denki Univ.)
Kotaro ISHII (QST)
Yusuke KAZAMA (Fukui Prefectural Univ.)
Yutaka MIYAZAWA (Yamagata Univ.)
Kazumitsu MIYOSHI (Chiba Univ.)

Koji MURAI (Fukui Prefectural Univ.)
Kyosuke NIWA (Tokyo Univ. of Marine Sci. and Tech.)Tadashi SATO (Tohoku Univ.)
Yoichi SATO (Riken Food Co., Ltd.)
Kenichi SUZUKI (Suntory Flowers Co., Ltd.)
Hinako TAKEHISA (Nat’l Agriculture and Food Res. Org.)
Masao WATANABE (Tohoku Univ.)
Alexis Kooichi VIDAL TAKASAKI (Pontiﬁcia Universidad
Católica de Valparaı́so)

Visiting Technicians
Yukiko KANAZAWA (Nippon Beet Sugar Manufacturing Co.,
Ltd.)
Norihide KISHINO (Sanwa Norin Co. Ltd.)
Research Fellow
Hirokazu SAIDO (Saitama Agricultural Tech. Res. Center)
Student Trainee
Yuzo MARUYAMA (Tokyo Denki Univ.)
Part-timer Worker
Haruka WATANABE- 325 -

Miho MOGAMIYA (Riken Food Co., Ltd.)
Daisuke SAITO (Riken Food Co., Ltd.)Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

List of Publications & Presentations
Publications[Original Papers]
A. Deguchi, F. Tatsuzawa, K. Ishii, T. Abe, and K. Miyoshi, “Localized repression of two bHLH genes is involved in the formation ofwhite margins and white abaxial surfaces in carnation petals by inducing the absence of anthocyanin synthesis,” Hortic. Sci. 91, 68(2022).
橋口太亮, 飯山光太郎, 長井純一, 藤川和博, 石井公太郎, 阿部知子, 「サツマイモ『シロユタカ』と外観識別可能な『こなみずき』
欠刻葉系統の作出」, 日本作物学会九州支部会報 88, 22 (2022).
H. Park, Y. Narasako, T. Abe, H. Kunitake, and T. Hirano, “Comprehensive eﬀects of heavy-ion beam irradiation on sweet potato (Ipomoea
batatas [L.] Lam.),” Plant Biotechnol (Tokyo) 39, 311 (2022).
Y. Kazama, M. Kitoh, T. Kobayashi, K. Ishii, M. Krasovec, Y. Yasui, T. Abe, S. Kawano, and D. A. Filatov, “A CLAVATA3-like gene acts
as a gynoecium suppression function in white campion,” Mol. Biol. Evol. 39, 10 (2022).
阿部知子, 林依子, 大野豊, 畑下昌範, 高城啓一, 「イオンビーム育種技術の開発に取り組む加速器施設」, アグリバイオ 6, 8 (2022).
平野智也, 「イオンビームを用いた花き植物の品種改良」, アグリバイオ 6, 14 (2022).
中村茂和, 阿部知子, 「長期貯蔵に適した温州みかん新品種『春しずか』の育成」, アグリバイオ 6, 24 (2022).
風間裕介, 畑下昌範, 木元久, 櫻井明彦, 「イオンビームを用いた微生物の品種改良」, アグリバイオ 6, 29 (2022).
H. J. Kim, K. Nakammura, Y. Sakakura, K. Suga, K. Tsuneizumi, T. Abe, M. Yamada, M. Kawada, T. Katayama, N. Tezuka, T. Kobayashi,
M. Koiso, and A. Hagiwara, “Eﬀects of dietary microalgal species and hormone treatment on the lorica size and reproductivity ofheavy-ion beam irradiated rotifers,” Fish. Sci. 89, 61 (2023).

[Review Articles]
T. Hirano, Y. Kazama, H. Kunitake, and T. Abe, “Mutagenic eﬀects of heavy-ion beam irradiation to plant genome,” Cytologia 87, 3(2022).
阿部知子, 「イオンビーム育種技術の開発—農学と加速器物理学のシナジー効果」, アグリバイオ 6, 6 (2022).

Presentations[International Conferences/Workshops]
T. Abe (invited), Y. Hayashi, R. Morita, Y. Shirakawa, and H. Ichida, “Ion-beam mutagenesis for creation of new varieties and discovery ofgenes,” Bangabandhu International Conference on Sustainable Agriculture through Nuclear and Frontier Research (Webinar), Online,
January 19–21, 2022.
Y. Kazama (oral) and T. Abe, “Eﬀect of linier energy transfer in the heavy-ion mutagenesis and breeding,” The 32nd Annual Meeting of
MRS-J, Yokohama, Japan, December 5–7, 2022.
T. Mayuzumi (poster), A. Matsuta, M. Hatashita, K. Takagi, T. Abe, K. Murai, and Y. Kazama, “Heavy-ion beams with high linear energy
transfer frequently produces morphological mutants in the M1 generation of an ornamental plant Torenia fournieri,” The 32nd Annual
Meeting of MRS-J, Yokohama, Japan, December 5–7, 2022.

[Domestic Conferences/Workshops]

石井公太郎 (口頭発表), 風間裕介, 浅野円花, 竹下毅, 阿部知子, 河野重行, 「クロレラの内部倍数性と Ar・Fe イオンビーム照射による染色体の分断化と再構成」, 日本藻類学会 第 45 回大会, オンライン, 2022 年 3 月 16–17 日.
石井公太郎 (口頭発表), 風間裕介, 平野智也, J. A. Fawcett, 酒井富士子, 白川侑希, 大部澄江, 阿部知子, 「重イオンビームで誘発される欠失変異と必須遺伝子のシロイヌナズナゲノム上での分布に関する俯瞰的解析」, 日本育種学会 第 141 回講演会, オンライ
ン, 2022 年 3 月 20–21 日.
杉田和陽 (口頭発表), サンジャヤ アルビン, 西嶋遼, 村井耕二, 阿部知子, 風間裕介, 「シロイヌナズナの新規染色体再編成変異体で見られたダイナミックな形態変化」, 同上.
黛隆宏 (口頭発表), 松田彩花, 畑下昌範, 高城啓一, 阿部知子, 村井耕二, 風間裕介, 「トレニアの新規フリル変異体で見られた花弁の細胞サイズの変化」, 同上.
H. Park (口頭発表), 奈良迫洋介, 阿部知子, 國武久登, 平野智也, 「重イオンビーム照射がサツマイモの塊根形成に及ぼす影響」, 同上.
小林壮生 (ポスター発表), 高橋真佐子, 杉山立志, 石井公太郎, 河野重行, 風間裕介, 「根端分裂組織の細胞周期の同調に着目したヒ
ロハノマンテマの染色体標本作製方法」, 同上.
椎槙子 (ポスター発表), 加治屋優希, 阿部知子, 星野洋一郎, 國武久登, 平野智也, 「アルゴンイオンビーム照射雄性配偶子の受精機構解析」, 園芸学会令和 4 年度秋季大会, 山形市 (山形大学), 2022 年 9 月 7–13 日.
武田信哉 (口頭発表), 市田裕之, 阿部知子, 有村慎一, 風間智彦, 陳孫禄, 金岡義高, 貴島祐治, 鳥山欽哉, 「台中 65 号の細胞質およびアフリカイネの核を持つ TG-CMS の原因遺伝子解析とその稔性回復様式の調査」, 第 39 回日本植物バイオテクノロジー学会, 堺
市 (大阪公立大学), 2022 年 9 月 11–13 日.
生駒拓也 (ポスター発表), サンジャヤ アルビン, 池田美穂, 西嶋遼, 村井耕二, 阿部知子, 風間裕介, 「シロイヌナズナ染色体における遺伝子量補正の調査」, 日本遺伝学会第 94 回大会, 札幌市 (北海道大学), 2022 年 9 月 14–17 日.
杉田和陽 (ポスター発表), サンジャヤアルビン, 西嶋遼, 田中裕之, 伊藤武彦, 村井耕二, 阿部知子, 風間裕介, 「シロイヌナズナの新規染色体部分的重複変異体における遺伝子発現変動とクロマチン動態」, 同上.
小川雅文 (ポスター発表), 常泉和秀, 阿部知子, 野澤昌文, 「重粒子線照射によるショウジョウバエ Y 染色体の部分破壊: 遺伝子量補償の即時性の検証に向けて」, 同上.

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池田公季 (ポスター発表), 旭置桐哉, 風間裕介, 石井公太郎, 阿部知子, 國武久登, 平野智也, 「シロイヌナズナ petal compensation
exhibiting 変異体における花器官細胞サイズ制御機構の解析」, 日本植物学会第 86 回大会, 京都市 (京都府立大), 2022 年 9 月
15–19 日.
石井公太郎 (口頭発表), 浅野円花, 阿部知子, 河野重行, 「クロレラゲノム配列の更新と重イオンビーム誘導変異体の染色体再編成の解析」, 同上.
田中朋之 (口頭発表), 小林麻子, 阿部知子, 「高温感受性イネ突然変異体 ﬂo11-2 を用いた白未熟粒発生機構の解析」, 第 254 回日本
作物学会講演会, 福島市 (福島大学), 2022 年 9 月 20–21 日.
市田裕之 (口頭発表), Ni Lei, 森田竜平, 阿部知子, 「機械学習による変異バリデーション法の開発と検証」, 日本育種学会 第 142 回講演会, 帯広市 (帯広畜産大学), 2022 年 9 月 23–25 日.
上田純平 (口頭発表), 風間裕介, 阿部知子, 村井耕二, 「時計遺伝子 WPCL1 の欠失による一粒系コムギ早生変異体の早生性を抑制
するイオンビーム変異体 late-heading1 の解析」, 同上.
杉田和陽 (口頭発表), サンジャヤアルビン, 西嶋遼, 田中裕之, 伊藤武彦, 村井耕二, 阿部知子, 風間裕介, 「染色体再編成が植物ゲノ
ムに及ぼす影響」, 北陸植物学会第 12 回大会, 富山市 (富山大学), 2022 年 11 月 13 日.
生駒拓也 (口頭発表), サンジャヤアルビン, 池田美穂, 西嶋遼, 村井耕二, 阿部知子, 風間裕介, 「シロイヌナズナで遺伝子量補正は起きるのか」, 同上.
黛隆宏 (口頭発表), 松田彩花, 畑下昌範, 高城啓一, 阿部知子, 村井耕二, 風間裕介, 「重イオンビームを用いた園芸植物トレニアの花形変異体の作出」, 同上.
鬼頭萌 (口頭発表), 小林壮生, 石井公太郎, M. Krasovic, 安井康夫, 阿部知子, 河野重行, D. A. Filaotv, 風間裕介, 「雌雄異株植物ヒロ
ハノマンテマの決定候補遺伝子 GSFY の同定」, 同上.
小林壮生 (口頭発表), 鬼頭萌, D. A. Filaotv, 風間裕介, 「ヒロハノマンテマ性決定遺伝子の X 染色体連鎖パラログ GSFX の機能解析」
, 同上.
風間裕介 (口頭発表), 鬼頭萌, 小林壮生, 石井公太郎, M. Krasovic, 安井康夫, 阿部知子, 河野重行, D. A. Filaotv, 「CLV3 様ペプチドはヒロハノマンテマの性を決定する」, 植物化学調節学会第 57 回大会, 吉田郡 (福井県立大), 2022 年 11 月 25–27 日.

Award阿部知子, 第 10 回和田賞, 公益財団法人日本メンデル協会, 4 月, 2022.

Press Releases「春先に出荷可能な温州みかんの作出に成功」, 2021 年 12 月 8 日.
“Accelerators accelerate many ﬁelds,” T. Abe, RIKEN People, December 20, 2021.
研究最前線「重イオンビームで温州みかんの品種改良」, RIKEN News 481, 18 (2022).
「巨大 Y 染色体発見から 99 年目の快挙—ヒロハノマンテマの性決定遺伝子の同定に成功—」, 2022 年 9 月 28 日.

Patent

蝶野真喜子, 神山紀子, 阿部知子, 「種子の白色性を向上させたコムギ」, 特許出願番号 2021-166243, 出願日 2021 年 10 月 8 日.

Outreach Activities

阿部知子, 「重イオンビームを用いて新しい品種を創る」, 第 9 回 理研イノベーションセミナー, オンライン, 2022 年 1 月 21 日.
阿部知子, 「重イオンビームを用いて新しい品種を創る」, 理研と未来を創る会第 28 回講演会・見学会, 和光市, 2022 年 9 月 6 日.
阿部知子,「加速器を用いた重イオンビーム育種の発展」, シンポジウム「理化学研究所仁科研究室のキセキ」, 和光市, 2022 年 10月 28 日.
We established the “Asagao (morning glory) club” to deepen the understanding of our technology of mutation breeding. The club
distributes the morning glory seeds irradiated with C-ion on request, and collects and compiles the observation reports of their growth.

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Accelerator Applications Research Division
Beam Mutagenesis Group
Plant Genome Evolution Research Team
1. Abstract

Established in May 2018 and succeed in October 2020, the plant genome evolution research team studies the eﬀect of heavyion induced mutations on plant and microbial phenotypes. Chromosome rearrangements including translocations, inversions, anddeletions are thought to play an important role in evolution and have a greater potential to achieve large phenotypic changes. However,this potential has not been fully investigated due to the lack of an eﬀective method to induce and analyze complexed mutations.
We employ the population genomics approach with robust molecular biology and bioinformatics techniques to characterize genomic
mutations in model and non-model plant and microbial species, and create the future of mutation breeding.

2. Major Research Subjects(1) Genomics-based approach to revolutionize the mutagenesis in model and non-model plants and microbes(2) De novo genome sequencing and assembly of cultivars and isolates, and its application to evolution and breeding studies

3. Summary of Research Activity(1) Genomics-based approach to revolutionize the mutagenesis in model and non-model plants and microbes
Recent advances in genome sequencing and bioinformatics technology enabled us to obtain a genome-wide view of the induced
mutations in unselected populations. We chose baker’s yeast and a legume Lotus japonicus as model systems, irradiated diﬀerent
doses of carbon-ion beams to these organisms, and determined the dose-survival correlation. We isolated a semi-dwarf L. japonicus
mutant, identiﬁed the responsible mutation by whole-genome sequencing, and started to characterize the phenotypic traits of thismutant. Phenotyping analysis indicated that the isolated semi-dwarf mutant shows signiﬁcantly shortened internode length while still
maintaining good seed production equivalent to the wild-type plants. The semi-dwarf L. japonicus mutant is suitable for high-density
cultivation in the laboratory environment and may serve as an eﬃcient model platform for legume- Rhizobium symbiosis.
(2) De novo genome sequencing and assembly of new cultivars and isolates, and its application to evolution and breedingstudies
We apply the latest de novo genome sequencing technology to elucidate genome sequences in diﬀerent cultivars and isolates andsuccessfully created some high-quality draft genome sequences. The determined and assembled draft genome sequences are subjected
to gene predictions and functional annotations, then shared in a searchable data visualization and analysis system accessible throughthe internet. With these fundamental genome information resources, we and our collaborators work together to achieve new ﬁndingsthat will achieve major advances in both science and practical applications. These resources as well as the overall experimental
techniques and the analysis pipeline are essential to further expand our genome-wide mutation and evolution approach to previously
uncharacterized non-model species.

Members
Team Leader
Hiroyuki ICHIDA
Postdoctoral Researcher
Ni LEI
Administrative Part-time Workers
Yusaku NISHIMIYA
Chiharu HINO

Keiko UEDA

List of Publications & Presentations
Publications[Original Papers]
H. Ichida, T. Kazama, S. Arimura, and K. Toriyama, “The mitochondrial and plastid genomes of Oryza sativa L. cv. Taichung 65,” Plant
Biotechnol. 40, 109 (2023).
H. Murata, N. Nakamura, A. Ohta, and H. Ichida, “A semisolid plate method to isolate mycelia maintaining chlamydospore formation in
Tricholoma bakamatsutake,” Bulletin of FFPRI 22, 13 (2023).

[Review Article]
H. Murata, A. Yamada, H. Ichida, N. Nakamura, and H. Neda, “Biodiversity of Tricholoma matsutake (syn. T. nauseosum) and its related
species based on repetitive DNA and genomics,” Botany (April 5, 2023), https://doi.org/10.1139/cjb-2022-0122 .

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Presentations[International Conference/Workshop]
T. Abe (invited), Y. Hayashi, R. Morita, Y. Shirakawa, and H. Ichida, “Ion-beam mutagenesis for creation of new varieties and discovery
of genes,” Bangabandhu International Conference on Sustainable Agriculture through Nuclear and Frontier Research, Online, January,
2022.

[Domestic Conferences/Workshops]

高塚歩, 風間智彦, 市田裕之, 阿部知子, 鳥山欽哉, 「Tadukan 型細胞質雄性不稔性イネのミトコンドリア RNA プロセッシングに関わる PPR 遺伝子の推定」, 第 10 回 植物 RNA 研究ネットワーク シンポジウム, 文京区, 2022 年 12 月.
市田裕之, Ni Lei, 森田竜平, 阿部知子, 「機械学習による変異バリデーション法の開発と検証」, 日本育種学会 第 142 回講演会, 帯広市, 2022 年 9 月.
稲田裕介, 高塚歩, 市田裕之, 鳥山欽哉, 「CW 型細胞質雄性不稔性イネに対するインディカ品種 Samba Mahsuri 由来の新規稔性回復遺伝子のマッピング」, 日本育種学会 第 142 回講演会, 帯広市, 2022 年 9 月.
高塚歩, 風間智彦, 市田裕之, 阿部知子, 鳥山欽哉, 「Tadukan 型細胞質雄性不稔性イネを稔性回復させる遺伝子の探索」, 日本育種学会 第 142 回講演会, 帯広市, 2022 年 9 月.
高塚歩, 風間智彦, 市田裕之, 阿部知子, 鳥山欽哉, 「Tadukan に由来する細胞質雄性不稔性イネの稔性回復候補遺伝子」, 第 39 回日
本植物バイオテクノロジー学会（堺）大会, 堺市, 2022 年 9 月.
武田信哉, 市田裕之, 阿部知子, 有村慎一, 風間智彦, 陳孫禄, 金岡義高, 貴島祐治, 鳥山欽哉, 「台中 65 号の細胞質とアフリカイネの核を持つ TG-CMS の原因遺伝子とその稔性回復様式の調査」, 第 39 回日本植物バイオテクノロジー学会（堺）大会, 堺市, 2022
年 9 月.

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RIKEN Accel. Prog. Rep. 56 (2023)

Accelerator Applications Research Division
RI Application Research Group
1. Abstract

RI Application Research Group promotes industrial applications of radioisotopes (RIs) 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)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)

Research and development of RI production technologies at RIBF
RI application researchDistribution of RIs produced at RIBF
Development of radioactive targets and sources
Development of trace element analyses using accelerator techniques and their applications to geoscience and archaeologicalresearch ﬁelds
Development of chemical materials for ECR ion sources of the RIBF accelerators
Development of technologies on industrial utilization and novel industrial applications of RIBF
Support of industrial utilization of the heavy-ion beams at RIBF
Support of materials science experiments

3. Summary of Research Activity

See the subsections of Nuclear Chemistry Research Team and Industrial Application Research Team.

MemberDirector
Hiromitsu HABA

List of Publications & Presentations
See the subsections of Nuclear Chemistry Research Team and Industrial Application Research Team.

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Accelerator Applications Research Division
RI Application Research Group
Nuclear Chemistry Research Team
1. Abstract

The Nuclear Chemistry Research Team develops production technologies of unique radioisotopes (RIs) at RIKEN RI Beam Factory (RIBF) and applies them in the research ﬁelds of physics, chemistry, biology, engineering, medicine, pharmaceutical and environmental sciences. 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
techniques and apply them to the research ﬁelds such as cosmochemistry, environmental science, archaeology, and so on. We perform
various isotopic analyses on the elements such as S, Pd, and Pb using ICP-MS, TIMS, and IRMS. We also develop radioactive targets
and sources, and chemical materials such as metallic 238 U, 238 UO2 , and 48 CaO 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 research(3) Development of trace element analyses using accelerator techniques and their applications to geoscience and archaeologicalresearch ﬁelds(4) Development of radioactive targets and sources, and 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 research
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 radioisotopes (RIs) at RIBF and conducting their application studies in collaboration withmany researchers in various ﬁelds. With 30-MeV proton, 24-MeV deuteron, 50-MeV alpha, and 70-MeV 7 Li beams from the AVF
cyclotron, we presently produce about 100 RIs from 7 Be to 236 Np. Among them, 65 Zn, 67 Cu, 85 Sr, 88 Y, and 109 Cd are delivered toJapan 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 in FY2016-2027.
On the other hand, RIs of a large number of elements are simultaneously produced from metallic targets such as nat Ti, nat Ag, nat Hf,
197
Au, and 232 Th irradiated with a 135 MeV/nucleon 14 N beam from the RIKEN Ring Cyclotron. These multitracers are also supplied
to universities and institutes as collaborative research.
In 2022, we developed production technologies of RIs such as 28 Mg, 44m Sc, 44 Ti, 67 Cu, 86 Y, 111 Ag, 139 Ce, 141 Ce, 155 Tb, 165 Er,
169
Yb, 186 Re, 195 Au, 211 At, 212 Pb, 224 Ra, 225 Ac, 229 Pa, and 236 Np which were strongly demanded but lack supply sources in Japan. We
also investigated the excitation functions for the 27 Al(α, x), nat Zn(p, x), nat Sm(7 Li, x), nat Gd(p, x), nat Re(d, x), nat Re(α, x), nat Ta(α, x),natW(p, x), nat Pt(p, x), nat Pt(α, x), and 209 Bi(7 Li, x) reactions to eﬀectively and quantitatively produce useful RIs. We used radiotracersof 139 Ce, 211 At, and 229 Pa for application studies in chemistry, 44m Sc, 67 Cu, 111 Ag, 141 Ce, 186 Re, 211 At, and 225 Ac in nuclear medicine,and 28 Mg, 44m Sc, 67 Cu, 86 Y, 169 Yb, 186 Re, and 211 At in engineering. We also produced 65 Zn, 67 Cu, 85 Sr, 88 Y, and 109 Cd for our scientiﬁc
research on a regular schedule and supplied the surpluses through Japan Radioisotope Association to the general public. In 2022, we
accepted 4 orders of 65 Zn with a total activity of 12.7 MBq, 4 orders of 85 Sr with 6.7 MBq, and 1 order of 88 Y with 0.1 MBq. We
also distributed 28 Mg (1 MBq × 2), 67 Cu (10 MBq × 1 and 100 MBq × 1), 86 Y (5 MBq × 1), 88 Zr (1 MBq × 2), 95 Nb (2 MBq × 2),
111
Ag (1 MBq × 1), 141 Ce (0.24 MBq × 1), 175 Hf (1 MBq × 2), 179 Ta (1 MBq × 1), and 211 At (5 MBq × 4, 10 MBq × 1, 30 MBq × 2,
50 MBq × 1, 80 MBq × 2, 90 MBq × 1, and 100 MBq × 2) under the Supply Platform of Short-lived Radioisotopes for Fundamental
Research.
(2) Superheavy element chemistry
Chemical characterization of newly-discovered superheavy elements (SHEs, atomic number Z ≥ 104) is an extremely interesting
and challenging research 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 SRILAC 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 SRILAC. 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. In 2022, we continued to develop an
ultra-rapid gas-chromatograph apparatus, which consists of an RF carpet gas cell and a cryo-gas-chromatograph column with a Si
detector array, at the focal plane of GARIS for the future gas-phase chemistry of the short-lived SHEs (half-life T 1/2 < 1 s). To
realize aqueous chemistry studies of Sg and Bh, we have been developing a continuous and rapid solvent extraction apparatus which- 331 -

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RIKEN Accel. Prog. Rep. 56 (2023)

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, in collaboration with Osaka University, co-precipitation behavior of No (Z = 102)
with BaSO4 and CaC2 O4 was investigated with 255 No produced in the 248 Cm(12 C, 5n)255 No reaction at the AVF cyclotron. We also
produced radiotracers of 88 Zr, 95 Nb, 175 Hf, and 179 Ta at the AVF cyclotron and conducted model experiments for aqueous chemistrystudies on Rf and Db.
(3) Development of trace element analyses using accelerator techniques and their applications to geoscience and archaeologicalresearch ﬁelds
We have been developing the ECR Ion Source Mass Spectrometer (ECRIS-MS) for trace element analyses. We renovated thedetection 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 ICP-MS, TIMS, IRMS, and so on, we studied Pb and S isotope ratios on cinnabar and asphalt samples from ancientruins in Japan to elucidate the distribution of goods in the archaic society. We have established a sampling technique for pigment
without any damages on the artifacts or wall paintings, using a sulfur-free adhesive tape since 2019. This technique was applied toanalyze vermilion samples collected from archaeological sites. In FY2022, three types of vermilion were analyzed. The ﬁrst wasvermilion excavated from tombs dating from the Yayoi Period to the Kofun Period in Japan, the second was excavated from tombs
dating from the Pre-Qin Period (the Shang, Spring and Autumn, Warring States Period, etc.) in China, and the third was used formurals on the Roman sites in the Iberian Peninsula. Furthermore, since 2021, we have been developing a method for the analyses of 3
isotopic abundance ratios (32 S, 33 S, and 34 S) of sulfur as a new parameter for identiﬁcation of source mine. We analyzed the possibilityof exploring the MIF (mass-independent-fractionation) eﬀect. This is also expected to provide a new parameter for the analysis ofenvironmental dynamics.
In FY2022, we operated ICP-MS, making it a shared-use instrument, and analyzed 294 samples from seven laboratories.
(4) Development of chemical materials for ECR ion sources of the heavy-ion accelerators at RIBF
In 2022, we prepared 238 UO2 on a regular schedule for 238 U-ion accelerations with the 28-GHz ECR of RILAC2.

Members
Team Leader
Hiromitsu HABA
Technical Scientist
Hiroo HASEBE
Contract Researcher
Xiaojie YIN
Postdoctoral Researcher
Yudai SHIGEKAWA
Technical Staﬀ
Akihiro NAMBU
Special Temporary Research Scientist
Kazuya TAKAHASHI
Junior Research Associates
Teruhito NAKASHITA

Motoki SATO

Research Part-time Workers
Michiko KITAGAWA
Nozomi SATO

Sachiko USUDA
Minako OSANAI

Research Consultant
Hisaaki KUDO (Niigata Univ.)
Visiting Scientists
Msayuki AIKAWA (Hokkaido Univ.)
Kazuhiko AKIYAMA (Tokyo Metropolitan Univ.)
Takatoshi AOKI (Univ. of Tokyo)
Masato ASAI (JAEA)
Ferenc DITROI (ATOMKI)
Shuichiro EBATA (Saitama Univ.)
Osuke FUJIMOTO (PDRadiopharma Inc.)

Yuichi FUNASE (PDRadiopharma Inc.)
Takahiro HIRAKI (Okayama Univ.)
Hayato IKEDA (Tohoku Univ.)
Masamichi KAJITA (PDRadiopharma Inc.)
Yoshitaka KASAMATSU (Osaka Univ.)
Hiroshi KATO (PDRadiopharma Inc.)
Mayeen U. KHANDAKER (Sunway Univ.)- 332 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Hidetoshi KIKUNAGA (Tohoku Univ.)
Yoshikatsu KOGA (Nat’l Cancer Center)
Shoko KUBOTA (PDRadiopharma Inc.)
Takumi KUBOTA (Kyoto Univ.)
Takahiko MASUDA (Okayama Univ.)
Toshimitsu MOMOSE (Int’l Univ. of Health and Welfare)Eri NAKAMURA (PDRadiopharma Inc.)
Kenichiro OGANE (Int’l Univ. of Health and Welfare)
Miki OHTSUKA (Waseda Univ.)
Kazuhiro OOE (Osaka Univ.)
Kai ORIHARA (PDRadiopharma Inc.)
Shinobu OSHIKIRI (PDRadiopharma Inc.)
Yasutaka SAITO (PDRadiopharma Inc.)
Aya SAKAGUCHI (Univ. of Tsukuba)
Miho SATAKE (PDRadiopharma Inc.)
Tetsuya SATO (JAEA)
Yuki SATO (PDRadiopharma Inc.)
Kenji SHIMAZOE (Univ. of Tokyo)

Keisuke SUEKI (Univ. of Tsukuba)
Kentaro SUZUKI (PDRadiopharma Inc.)
Zoltan SZUCS (ATOMKI)
Sandor TAKACS (ATOMKI)
Hiroyuki TAKAHASHI (Univ. of Tokyo)
Miho TAKAHASHI (Tokyo Univ. of Marine Sci. and Tech.)
Hiroki TAKASHIMA (Nat’l Cancer Center)
Sayuri TAKATORI (Okayama Univ.)
Atsushi TOYOSHIMA (Osaka Univ.)
Kazuaki TSUKADA (JAEA)
Mizuki UENOMACHI (Kyoto Univ.)
Naoyuki UKON (Fukushima Medical Univ.)
Takahiro YAMADA (Kindai Univ.)
Takuya YOKOKITA (Salesian Polytechnic)
Akihiko YOKOYAMA (Kanazawa Univ.)
Zenko YOSHIDA (ATOX Co., Ltd.)
Koji YOSHIMURA (Okayama Univ.)

Visiting Technicians
Hideyuki ARAI (Metal Tech. Co., Ltd.)
Hiroshi ARATA (Metal Tech. Co., Ltd.)
Mai FUKUMORI (ATOX Co., Ltd.)
Masataka IMAMURA (Japan Radioisotope Association)
Shota KIMURA (Japan Radioisotope Association)
Yukiyoshi KON (Osaka Univ.)
Takashi KURIHARA (Metal Tech. Co., Ltd.)
Daiki MORI (Japan Radioisotope Association)

Shingo NAKAMURA (Metal Tech. Co., Ltd.)
Yuki TAKEMURA (ATOX Co., Ltd.)
Shusaku TAZAWA (ATOX Co., Ltd.)Sho TOMITA (ATOX Co., Ltd.)
Yuichirou WAKITANI (Japan Radioisotope Association)
Kaede YAMADA (ATOX Co., Ltd.)
Mami YUKI (ATOX Co., Ltd.)

Visiting Researcher
Mizuki UENOMACHI (Kyoto Univ.)
Student Trainees
Kjeld A.A.G. BEEKS (Vienna Univ. of Tech.)
Desheng CHEN (Univ. of Chinese Academy of Sci.)
Gantumur DAMDINSUREN (Hokkaido Univ.)
Shunsuke FUJINO (Kindai Univ.)
Yuta FUKUNAGA (Okayama Univ.)
Ming GUAN (Okayama Univ.)
Hiroyuki HOSOKAWA (Kanazawa Univ.)
Xuan HOU (Univ. of Tokyo)
He HUANG (Hokkaido Univ.)
Yuki ISHII (Kanazawa Univ.)
Yudai ITAKURA (Osaka Univ.)
Donghwan KIM (Univ. of Tokyo)
Hongchang LIN (Univ. of Tokyo)
Ryoutarou MASUDA (Osaka Univ.)

Kenichi MORI (Kindai Univ.)
Ayumu NAGAI (Kanazawa Univ.)
Ryohei NAKANISHI (Osaka Univ.)
Teruhito NAKASHITA (Univ. of Tokyo)
Koichi OKAI (Okayama Univ.)
Saki OTAKA (Osaka Univ.)
Yuma SAKAKIEDA (Univ. of Tsukuba)
Motoki SATO (Univ. of Tokyo)
Hodaka TAKAHASHI (Univ. of Tsukuba)
Katsuyuki TOKOI (Osaka Univ.)
Yutaka TOYOEDA (Hokkaido Univ.)
Taisei UEKI (Univ. of Tokyo)
Ruilin WANG (Osaka Univ.)
Eisuke WATANABE (Osaka Univ.)

List of Publications & Presentations
Publications[Original Papers]
K. Ohnuki, M. Yoshimoto, H. Haba, S. Manabe, H. Takashima, M. Yasunaga, Y. Takenaka, and H. Fujii, “Protection from contamination
by 211 At, an enigmatic but promising alpha-particle-emitting radionuclide,” EJNMMI Phy. 9, 39 (2022).
M. Aikawa, M. Sakaguchi, N. Ukon, Y. Komori, H. Haba, N. Otuka, and S. Takács, “Production cross sections of samarium-153 and -145
via alpha-particle-induced reactions on natural neodymium,” Appl. Radiat. Isot. 187, 110345 (2022).
A. Yakushev, L. Lens, Ch. E. Düllmann, J. Khuyagbaatar, E. Jäger, J. Krier, J. Runke, H. M. Albers, M. Asai, M. Block, J. Despotopulos,
A. Di Nitto, K. Eberhardt, U. Forsberg, P. Golubev, M. Götz, S. Götz, H. Haba, L. Harkness-Brennan, R. -D. Herzberg, F. P. Heßberger,
D. Hinde, A. Hübner, D. Judson, B. Kindler, Y. Komori, J. Konki, J. V. Kratz, N. Kurz, M. Laatiaoui, S. Lahiri, B. Lommel, M. Maiti,
A. Mistry, Ch. Mokry, K. J. Moody, Y. Nagame, J. P. Omtvedt, P. Papadakis, V. Pershina, D. Rudolph, L. G. Samiento, T. K. Sato,
M. Schädel, P. Scharrer, B. Schausten, D. A. Shaughnessy, J. Steiner, P. Thörle-Pospiech, A. Toyoshima, N. Trautmann, K. Tsukada,J. Uusitalo, K. -O. Voss, A. Ward, M. Wegrzecki, N. Wiehl, E. Williams, and V. Yakusheva, “On the adsorption and reactivity ofelement 114, ﬂerovium,” Front. Chem. 10, published online (August 25, 2022). DOI: 10.3389/fchem.2022.976635 .

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T. Watabe, Y. Liu, K. Kaneda-Nakashima, T. Sato, Y. Shirakami, K. Ooe, A. Toyoshima, E. Shimosegawa, Y. Wang, H. Haba, T. Nakano,
A. Shinohara, and J. Hatazawa, “Comparison of the therapeutic eﬀects of [211 At]NaAt and [131 I]NaI in an NIS-expressing thyroid
cancer mouse model,” Int. J. Mol. Sci. 23, 9434 (2022).
M. Tanaka, P. Brionnet, M. Du, J. Ezold, K. Felker, B. J. P. Gall, S. Go, R. K. Grzywacz, H. Haba, K. Hagino, S. Hogle, S. Ishizawa,D. Kaji, S. Kimura, T. T. King, Y. Komori, R. K. Lemon, M. G. Leonard, K. Morimoto, K. Morita, D. Nagae, N. Naito, T. Niwase,
B. C. Rasco, J. B. Roberto, K. P. Rykaczewski, S. Sakaguchi, H. Sakai, Y. Shigekawa, D. W. Stracener, S. VanCleve, Y. Wang,
K. Washiyama, and T. Yokokita, “Probing optimal reaction energy for synthesis of element 119 from 51 V + 248 Cm reaction withquasielastic barrier distribution measurement,” J. Phys. Soc. Jpn. 91, 084201 (2022).
A. C. Berriman, D. J. Hinde, D. Y. Jeung, M. Dasgupta, H. Haba, T. Tanaka, K. Banerjee, T. Banerjee, L. T. Bezzina, J. Buete, K. J. Cook,
S. Parker-Steele, C. Sengupta, C. Simenel, E. C. Simpson, M. A. Stoyer, B. M. A. Swinton-Bland, and E. Williams, “Energy dependenceof p+232 Th ﬁssion mass distributions: Mass-asymmetric standard I and standard II modes, and multichance ﬁssion,” Phys. Rev. C 105,
064614 (2022).
S. Ebata, M. Aikawa, D. Gantumur, and H. Haba, “Activation cross sections of alpha-particle-induced reactions on natural lanthanum up
to 50 MeV,” Nucl. Instrum. Methods Phys. Res. B 530, 18 (2022).
H. Huang, M. Aikawa, Y. Hanada, and H. Haba, “Activation cross sections of deuteron-induced reactions on natural chromium up to
24 MeV,” Nucl. Instrum. Methods Phys. Res. B 530, 23 (2022).
A. Aso, K. Kaneda-Nakashima, H. Nabetani, Y. Kadonaga, Y. Shirakami, T. Watabe, T. Yoshiya, M. Mochizuki, Y. Koshino, K. Ooe,
A. Kawakami, N. Jinno, A. Toyoshima, H. Haba, Y. Wang, J. Cardinale, F. L. Giesel, A. Shimoyama, and K. Fukase, “Substrate study
for dihydroxyboryl astatine substitution reaction with Fibroblast Activation Protein Inhibitor (FAPI),” Chem. Lett. 51, 1091 (2022).
T. Watabe, K. Kaneda-Nakashima, Y. Shirakami, Y. Kadonaga, K. Ooe, Y. Wang, H. Haba, A. Toyoshima, J. Cardinale, F. L. Giesel,
N. Tomiyama, and K. Fukase, “Targeted α-therapy using astatine (211 At)-labeled PSMA1, 5, and 6: a preclinical evaluation as a novelcompound,” Eur. J. Nucl. Med. Mol. Imaging 50, 849 (2023).
H. Sakai, H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for superheavy-element research at RIKEN,” Eur. Phys. J. A 58,
238 (2022).
X. Huang, K. Kaneda-Nakashima, Y. Kadonaga, K. Kabayama, A. Shimoyama, K. Ooe, H. Kato, A. Toyoshima, A. Shinohara, H. Haba,
Y. Wang, and K. Fukase, “Astatine-211-labeled gold nanoparticles for targeted alpha-particle therapy via intravenous injection pharmaceutics,” Pharmaceutics 14, 2705 (2022).
H. Takashima, K. Ohnuki, S. Manabe, Y. Koga, R. Tsumura, T. Anzai, Y. Wang, X. Yin, N. Sato, Y. Shigekawa, A. Nambu, S. Usuda,
H. Haba, H. Fujii, and M. Yasunaga, “Tumor targeting of 211 At-labeled antibody under sodium ascorbate protection against radiolysis,”Mol. Pharm. 20, 1156 (2023).
K. Kaneda-Nakashima, Y. Shirakami, T. Watabe, K. Ooe, T. Yoshimura, A. Toyoshima, Y. Wang, H. Haba, and K. Fukase, “Eﬀect
to therapy of sodium-iodine symporter expression by alpha-ray therapeutic agent via sodium/iodine symporter,” Int. J. Mol. Sci. 23,
15509 (2022).
M. Uenomachi, K. Shimazoe, and H. Takahashi, “Double photon coincidence crosstalk reduction method for multi-nuclide Compton
imaging,” J. Instrm. 17, P04001 (2022).
Y. Kasamatsu, M. Nagase, H. Ninomiya, E. Watanabe, Y. Shigekawa, N. Kondo, K. Takamiya, T. Ohtsuki, N. Shiohara, and A. Shinohara,“Coprecipitation with samarium hydroxide using multitracer produced through neutron-induced ﬁssion of 235 U toward chemical studyof heavy elements,” Appl. Radiat. Isot. 179, 110006 (2022).
Y. Miyake, N. Ikoma, K. Takahashi, Y. V. Sahoo, and H. Okuno, “Test of 107 Pd transmutation with macroscopic quantities,” J. Nucl. Sci.
Technol. 59, 1536 (2022).
青木貴稔, 佐藤拓海, 池田英彦, 岡本直大, 鳥井寿夫, 中村圭佑, 永瀬慎太郎, 長濱弘季, 小澤直也, 佐藤幹, 中下輝士, 山根風樹, 松田
恭幸, 酒見泰寛, 早水友洋, 大塚未来, 高峰愛子, 上野秀樹, 羽場宏光, 田中香津生, 原田健一, 川村広和, 井上壮志, 内山愛子, 畠山温, 市川雄一, 田中聡, 松尾由賀利, R. Sreekantham, B. K. Sahoo, B. Arora, and A. Kastberg, 「量子エンタングル Fr 原子を用いた
電子 EDM の量子センシング」, 電気学会研究会資料 40-44, 17 (2022).
D. Gantumur, M. Aikawa, T. Khishigjargal, E. Norov, N. Ukon, and H. Haba, “Activation cross sections of proton-induced reactions on
natural platinum up to 30 MeV,” Appl. Radiat. Isot. 192, 110621 (2023).
D. Ichinkhorloo, M. Aikawa, Z. Tsoodol, Y. Komori, and H. Haba, “Production cross sections of terbium and gadolinium radioisotopes
from the deuteron-induced reactions on natural gadolinium up to 24 MeV,” Nucl. Instrum. Methods Phys. Res. B 536, 30 (2023).
Y. Osuka, K. Ii, K. Tsuchiya, M. Nemoto, Y. V. Sahoo, K. Takahashi, and M. Tanaka, “Molecular speciation of isopolyoxomolybdates andisopolyoxotungstates with silicic acid in aqueous solution using ESI-MS,” J. Solution Chem., published online (February 27, 2023).
DOI: 10.1007/s10953-023-01255-6 .

[Review Articles]

羽場宏光, 「人工元素合成」, 科学 92, 846 (2022).
羽場宏光, 「加藤セチ」, 和光純薬時報 91, 32 (2023).

[Books]

羽場宏光, 「元素探索と RI 製造」 in 「量子ビーム科学の基礎と応用」, NSA/Commentaries No. 27, 一般社団法人日本原子力産業協会原子力システム研究懇話会, 195 ページ, 2023 年 3 月 24 日, pp. 26–39.
桜井弘（編）, 荒野泰, 小谷明, 高妻孝光, 佐治英郎, 鈴木晋一郎, 中山祐正, 根矢三郎, 羽場宏光, 廣田俊, 藤井敏司, 「ブルーバックス
元素 118 の新知識 第 2 版」
, 講談社, 560 ページ, 2023 年 3 月 20 日.
上条信彦, 高橋和也, 「アスファルト分析」 in 「杉沢 C 遺跡第 1・2 次発掘調査報告書」（山形県埋蔵文化財センター調査報告書,- 334 -

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第 246 集）, 公益財団法人山形県埋蔵文化財センター, 256 ページ, 2023 年 3 月, pp. 208–210.

[Proceedings]

H. Sakai, H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for SHE research at RIKEN Nishina Center,” Acta Phys. Pol. B
Proc. Suppl. 16, 4-A10 (2023).
K. Nakamura, S. Nagase, T. Nakashita, T. Hayamizu, T. Aoki, H. Nagahama, N. Ozawa, M. Sato, K. Yamane, M. Fukase, D. Uehara,
A. Takamine, and Y. Sakemi, “400-m-long polarization-maintaining ﬁbers for magneto-optical trapping of francium atoms,” Proc. 2022
Conf. on Lasers and Electro-Optics Paciﬁc Rim, Technical Digest Series (Optica Publishing Group, 2022), CTuP7C 03, pp. 1–2.
A. Mukai, S. Hara, K. Yamagishi, R. Terabayashi, K. Shimazoe, Y. Tamura, H. Woo, T. Kishimoto, H. Kogami, Z. Zhihong, M. Uenomachi, A. Nurrachman, H. Takahashi, H. Asama, F. Ishida, H. Ebi, E. Takada, J. Kawarabayashi, K. Tanabe, K. Kamada, and H. Tomita,“Optimization of detector movement algorithm using decision trees analysis for radiation source identiﬁcation based on 4π gamma
imaging,” 2022 IEEE/SICE International Symposium on System Integration (SII), Narvik, Norway, 2022, pp. 1026–1029.

Presentations[International Conferences/Workshops]
H. Haba (invited), “Production and applications of radioisotopes at RIKEN RI Beam Factory—Search for new elements through diagnosis
and therapy of cancer—,” Laser Solutions for Space and the Earth 2022 in OPTICS & PHOTONICS International Congress 2022 (OPIC2022), Yokohama, Japan & Online, April 18–22, 2022.
M. Tanaka (invited) for nSHE Collaboration, “Quasielastic backscattering measurement for 51 V + 248 Cm reaction toward element-119
synthesis at RIKEN,” 19th Workshop on Recoil Separator for Superheavy Element Chemistry and Physics (TASCA 22), Darmstadt,
Germany & Online, May 10–12, 2022.
K. Ooe (oral), S. Naka, Y. Shirakami, E. Shimosegawa, H. Kato, M. Tatsumi, H. Haba, A. Toyoshima, and T. Watabe, “Manufacturing of[211 At]NaAt for the ﬁrst-in-human clinical trial of targeted alpha therapy for diﬀerentiated thyroid cancer at Osaka University Hospital,”
SNMMI 2022 Annual Meeting, Vancouver, Canada, June 11–14, 2022.
Y. Shirakami (oral), T. Watabe, K. Kaneda, Y. Kadonaga, K. Ooe, Y. Wang, H. Haba, A. Toyoshima, and K. Fukase, “Synthesis andpreclinical evaluation of PSMA ligands labeled with astatine-211,” SNMMI 2022 Annual Meeting, Vancouver, Canada, June 11–14,
2022.
T. Watabe (oral), K. Kaneda-Nakashima, Y. Shirakami, Y. Kadonaga, K. Ooe, Y. Wang, H. Haba, A. Toyoshima, and K. Fukase, “Targeted alpha therapy using astatine (211 At)-labeled PSMA5: a preclinical evaluation as a new novel compound,” SNMMI 2022 Annual
Meeting, Vancouver, Canada, June 11–14, 2022.
H. Haba (invited), “Production and applications of radioisotopes at RIKEN RI Beam Factory—Search for new elements through diagnosis
and therapy of cancer—,” IAEA/RCA RTC on Good Manufacturing Practice (GMP) and Radiation Safety Aspects of Radiopharmaceutical Production Using Medical Cyclotron, Online, May16–20, 2022.
M. Uenomachi (oral), T. Ueki, K. Shimazoe, H. Takahashi, Y. Shigekawa, A. Nambu, X. Yin, Y. Wang, and H. Haba, “Simultaneous multinuclide double photon coincidence imaging with parallel and slit collimators,” 9th Conference on New Developments in Photodetection,
Troyes, France, July 4–8, 2022.
K. Nakamura (oral), S. Nagase, T. Nakashita, T. Hayamizu, T. Aoki, H. Nagahama, N. Ozawa, M. Sato, K. Yamane, M. Fukase, D. Uehara,
A. Takamine, and Y. Sakemi, “400-m-long polarization-maintaining ﬁbers for magneto-optical trapping of francium atoms,” The 15th
Paciﬁc Rim Conference on Lasers and Electro-Optics (CLEO Paciﬁc Rim, CLEO-PR 2022), Sapporo & Online, July 31–August 5,
2022.
H. Sakai (invited), H. Haba, K. Morimoto, and N. Sakamoto, “Facility upgrade for SHE research at RIKEN,” Zakopane Conference on
Nuclear Physics “Extremes of the Nuclear Landscape,” Zakopane, Poland, August 28–September 4, 2022.
M. Tanaka (oral) for nSHE Collaboration, “Optimal energy for element 119 synthesis via 51 V + 248 Cm reaction probed by quasielastic
barrier distribution measurement,” Zakopane Conference on Nuclear Physics “Extremes of the Nuclear Landscape,” Zakopane, Poland,
August 28–September 4, 2022.
A. Yamaguchi (invited), Y. Shigekawa, H. Haba, M. Wada, and H. Katori, “Laser spectroscopy of triply charged thorium ions towards a
nuclear clock,” 2022 URSI-Japan Radio Science Meeting (URSI-JRSM 2022), Bunkyo-ku, Tokyo, September 1–2, 2022.
W. Xian (oral), S. Chen, M. Rosenbusch, S. Yan, D. Hou, S. Iimura, A. Takamine, M. Wada, J. Lee, J. Liu, P. Schury, F. Browne,
F. Flavigny, H. Haba, S. Kimura, H. Koura, T. Niwase, Y. Ito, T. Sonoda, T. M. Kojima, Y. X. Watanabe, S. Naimi, S. Michimasa,
H. Miyatake, J. Y. Moon, S. Nishimura, H. Ishiyama, and H. Wollnik, “New mass measurements of neutron-rich nuclei of Ge, As, andSe, and an accuracy study of the new ZD-MRTOF system,” The 28th International Nuclear Physics Conference (INPC 2022), CapeTown, South Africa, September 11–16, 2022.
S. Sakaguchi (poster) and M. Tanaka for nSHE Collaboration, “Probing optimal energy for synthesis of element 119 from 51 V + 248 Cm
reaction,” The 28th International Nuclear Physics Conference (INPC 2022), Cape Town, South Africa, September 11–16, 2022.
A. Takamine (invited), D. Kaji, H. Haba, M. Wada, P. Schury, H. Koura, H. Wollnik, H. Miyatake, H. Ishiyama, K. Morimoto, M. Rosenbusch, S. Kimura, T. Niwase, Y. Hirayama, Y. Ito, Y. Watanabe, and P. Brionnet, “Multi-reﬂection time-of-ﬂight mass spectroscopy ofsuperheavy nuclides,” 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS 2022), Daejeon,
Korea, October 3–7, 2022.
G. Damdinsuren (poster), M. Aikawa, K. Tegshjargal, N. Erdene, N. Ukon, and H. Haba, “Production cross sections of 198g Au in protoninduced reactions on natural platinum,” 2022 Symposium on Nuclear Data, Higashiosaka, Japan, November 17–18, 2022.
H. Haba (invited), “Production and distribution of radioisotopes at RIKEN RI Beam Factory,” PRISMAP workshop on emerging infrastructures and technical developments, Padova, Italy & Online, November 21–22, 2022.

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H. Haba (invited), “Production of radioisotopes for application studies at RIKEN RI Beam Factory—Search for new elements throughdiagnosis and therapy of cancer,” The Fifth International Conference on Application of RadiotraCers and Energetic Beams in Sciences(ARCEBS 2023), Purulia, India, January 31–February 5, 2023.
Y. Shigekawa (oral), W. Yang, Y. Xiaojie, A. Nambu, and H. Haba, “Progress toward observing γ-rays emitted from 229m Th by doping
ﬂuoride crystals with 229 Pa,” The Fifth International Conference on Application of RadiotraCers and Energetic Beams in Sciences(ARCEBS 2023), Purulia, India, January 31–February 5, 2023.
H. Haba (invited), “Synthesis of radioactive isotope for gamma-ray imaging,” Workshop on Double Photon Emission Computed Tomography and beyond, Bunkyo-ku, Japan, March 24, 2023.

[Domestic Conferences/Workshops]

髙島大輝 (口頭発表), 大貫和信, 眞鍋史乃, 古賀宣勝, 津村遼, 安西高廣, Wang Yang, Yin Xiaojie, 佐藤望, 重河優大, 南部明弘, 臼田
祥子, 羽場宏光, 藤井博史, 安永正浩, 「アスコルビン酸 Na は放射線分解による能動的標的化の障害からアスタチン-211 結合抗体を保護する」, 第 38 回日本 DDS 学会学術集会, オンライン, 2022 年 6 月 29–30 日.
髙島大輝 (口頭発表), 眞鍋史乃, 大貫和信, 古賀宣勝, 津村遼, 安西高廣, Wang Yang, Yin Xiaojie, 佐藤望, 重河優大, 南部明弘, 臼田
祥子, 羽場宏光, 藤井博史, 松村保広, 安永正浩, 「アルファ線放出核種アスタチン-211 結合抗体の前臨床試験」, 第 26 回日本がん
分子標的治療学会学術集会, 金沢市, 2022 年 6 月 29 日–7 月 1 日.
渡部直史 (口頭発表), 仲定宏, 大江一弘, 豊嶋厚史, 王洋, 羽場宏光, 白神宜史, 「難治性甲状腺がんに対するアスタチンを用いた医師主導治験」, 第 59 回アイソトープ・放射線研究発表会, オンライン, 2022 年 7 月 6 日–8 日.
藤野隼輔 (口頭発表), 森健一, 山田崇裕, 羽場宏光, Wang Yang, Yin Xiaojie, 南部明弘, 「液体シンチレーション検出器を用いた効率
トレーサ法による 211 At 放射能測定法の検討」, 第 59 回アイソトープ・放射線研究発表会, オンライン, 2022 年 7 月 6 日–8 日.
新井香純 (口頭発表), 今村正隆, 森大輝, 石津秀剛, 佐藤泰, 羽場宏光, Xiaojie Yin, Yang Wang, 脇谷雄一郎, 「Ac-225, At-211 放射能校正の検討」, 第 59 回アイソトープ・放射線研究発表会, オンライン, 2022 年 7 月 6 日–8 日.
岡井晃一 (口頭発表), Kjeld Beeks, 藤本弘之, 福永優太, 管明, 羽場宏光, 原秀明, 平木貴宏, 稲垣新, 小早川大貴, 笠松良崇, 北尾真司,
小無健司, 増田孝彦, 宮本祐樹, 笹尾登, Thorsten Schumm, 瀬戸誠, 重河優大, 高取沙悠理, 玉作賢治, 植竹智, 渡部司, 渡部信, 山口
敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦, 「トリウム 229 アイソマー状態からの脱励起に伴う真空紫外光の探索」, 日本物理学会 2022 秋季大会, 岡山市, 2022 年 9 月 6–8 日.
Guan Ming (口頭発表), 岡井晃一, Kjeld Beeks, 藤本弘之, 福永優太, 羽場宏光, 原秀明, 平木貴宏, 稲垣新, 小早川大貴, 笠松良崇, 北尾
真司, 小無健司, 増田孝彦, 宮本祐樹, 笹尾登, Thorsten Schumm, 瀬戸誠, 重河優大, 高取沙悠理, 玉作賢治, 植竹智, 渡部司, 渡部
信, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦, “New methods in searching for vacuum ultraviolet signal from theisomeric state of 229-thorium,” 日本物理学会 2022 秋季大会, 岡山市, 2022 年 9 月 6–8 日.
渡部直史 (口頭発表), 兼田加珠子, 白神宜史, 角永悠一郎, 大江一弘, 王洋, 羽場宏光, 豊嶋厚史, 深瀬浩一, 「211 At 標識 PSMA-5 を用いた標的アルファ線治療: 非臨床での評価」, 第 62 回日本核医学会学術総会, 京都市, 2022 年 9 月 7–11 日.
白神宜史 (口頭発表), 渡部直史, 兼田加珠子, 角永悠一郎, 大江一弘, 羽場宏光, 豊嶋厚史, 深瀬浩一, 「前立腺癌の α 線核医学治療に用いるアスタチン-211 標識 PSMA の調製」
, 第 62 回日本核医学会学術総会, 京都市, 2022 年 9 月 7–11 日.
大江一弘 (口頭発表), 仲定宏, 白神宜史, 下瀬川恵久, 加藤弘樹, 巽光朗, 羽場宏光, 豊嶋厚史, 渡部直史, 「分化型甲状腺がんのアルファ線核医学治療第 I 相試験のためのアスタチン化ナトリウムの製造」, 第 62 回日本核医学会学術総会, 京都市, 2022 年 9 月
7–11 日.
青木貴稔 (口頭発表), 鳥井寿夫, 早水友洋, 中村圭佑, 長濱弘季, 田中香津生, 原田健一, 内山愛子, 畠山温, 高峰愛子, 上野秀樹, 市川雄一, 松田恭幸, 羽場宏光, 酒見泰寛, 「量子エンタングル Fr 原子を用いた電子 EDM の量子センシング」, 電子回路研究会「次世代周波数精密計測に向けた研究開発」, 小金井市, 2022 年 9 月 8 日.
山口敦史 (口頭発表), 重河優大, 羽場宏光, 和田道治, 香取秀俊, 「原子核時計実現にむけたトリウムイオントラップ装置の開発」,日
本物理学会 2022 秋季大会（物性）, 目黒区, 2022 年 9 月 12–15 日.
南部明弘 (ポスター発表), 殷小杰, 重河優大, 羽場宏光, 富田翔, 福森麻衣, 田沢周作, 「α 線核医学治療用核種 Pb-212 の製造に向けた Th-228 線源の取扱方法の検討」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
大江一弘 (ポスター発表), 渡部直史, 白神宜史, 南部明弘, 羽場宏光, 畑澤順, 「核医学利用に向けた Ce-141 の加速器製造と分離精製の検討」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
殷小杰 (ポスター発表), 南部明弘, 押切忍, 鈴木健太郎, 日野明弘, 羽場宏光, 「Production cross sections of 225 Ac and 225 Ra in the232
Th(14 N, xnyp) reactions (2)」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
殷小杰 (ポスター発表), 福地知則, 渡辺恭良, 羽場宏光, 「Production of 44 Ti via the 45 Sc(p, 2n)44 Ti reaction for 44 Ti/44g Sc generator
development」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
床井健運 (ポスター発表), 青戸宏樹, 渡邉瑛介, 篠原厚, 王洋, 羽場宏光, 笠松良崇, 豊嶋厚史,「ガスクロマトグラフィーを用いた Atのハロゲン結合エネルギーの導出法の開発」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
細川浩由 (ポスター発表), 瀬戸彩乃, 永井歩夢, 中島朗久, 坂口綾, 羽場宏光, 横山明彦, 「Th ターゲット中に生成する Np の単離を目的とした高除染係数溶媒抽出法の検討」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
寺本高啓 (ポスター発表), 加納英明, WANG Yang, 羽場宏光, 豊嶋厚史, 「アスタチン化合物の表面増強ラマン分光」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
秋山和彦 (ポスター発表), 諏訪智也, 羽場宏光, 菊永英寿, 久冨木志郎, 「Pm を内包した二金属内包フラーレンの安定性に関する研究」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
益田遼太郎 (ポスター発表), 安田勇輝, 澤村慶, 重河優大, 宮本祐樹, 吉村浩司, 篠原厚, 笠松良崇, 「229m Th の γ 線測定に向けた希ガ
スマトリックス単離装置の開発」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
永井雄太 (口頭発表), 我那覇功也, 西中一朗, 鷲山幸信, 殷小杰, 南部明弘, 羽場宏光, 横山明彦, 「Rn の液相回収と At のイオン液体- 336 -

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抽出による 211 Rn/211 At ジェネレータシステムの開発」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
我那覇功也 (口頭発表), 永井雄太, 西中一朗, 鷲山幸信, 殷小杰, 南部明弘, 羽場宏光, 横山明彦, 「DIPE/HCl 系と HCl/イオン液体系の 211 At 溶媒抽出における線量効果について」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
久下恒明 (口頭発表), 増田寛喜, 杜婉瑩, 保田智彦, 杉山暁, 羽場宏光, 巽俊文, 秋光信佳, 熊倉嘉貴, 吉田寛, 瀬戸康之, 和田洋一郎,
野村幸世, 「胃癌腹膜播種モデルマウスを用いた 211 At 標識抗 FGFR4 抗体による放射線免疫療法の検討」, 日本放射化学会第 66
回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
中川創太 (口頭発表), 角永悠一郎, 大江一弘, 寺本高啓, 床井健運, 永田光知郎, 吉村崇, 羽場宏光, 王洋, 笠松良崇, 豊嶋厚史, 深瀬
浩一, 篠原厚, 「電解酸化反応を用いたチロシン上ヨウ素-アスタチン置換反応」, 日本放射化学会第 66 回討論会 (2022), 文京区,
2022 年 9 月 15–17 日.
永井歩夢 (口頭発表), 細川浩由, 中島朗久, 坂口綾, 南部明弘, 重河優大, 羽場宏光, 横山明彦, 「232 Th + 7 Li 核反応によって生成する
U 同位体の ICP-MS による定量」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
重河優大 (口頭発表), Wang Yang, Yin Xiaojie, 南部明弘, 羽場宏光, 「Th-229m の γ 線観測に向けた Pa-229 のフッ化物結晶への導入法及び光子測定装置の開発」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
渡邉瑛介 (口頭発表), 笠松良崇, 横北卓也, 中西諒平, 大髙咲希, 板倉悠大, 益田遼太郎, 王瑞麟, 重河優大, 南部明弘, 殷小杰, 羽場
宏光, 高宮幸一, 篠原厚, 「クラウンエーテルを用いた 102 番元素ノーベリウムの硝酸系固液抽出実験」, 日本放射化学会第 66 回
討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
中西諒平 (口頭発表), 渡邉瑛介, 大髙咲希, 王瑞麟, 板倉悠大, 速水翔, 羽場宏光, 南部明弘, 篠原厚, 笠松良崇, 「Rf の共沈実験に向けた Zr, Hf, Th のシュウ酸, マロン酸系でのフロー式共沈実験」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月
15–17 日.
黒田拓真 (口頭発表), 西村峻, 秋山和彦, 羽場宏光, 高宮幸一, 久冨木志郎, 「ランタノイド内包フラーレン（Ln3+ @C82 3− ）におけるHPLC 溶出挙動の熱力学的解析」, 日本放射化学会第 66 回討論会 (2022), 文京区, 2022 年 9 月 15–17 日.
白神宜史 (口頭発表), 角永悠一郎, 渡部直史, 兼田加珠子, 神野直哉, 大江一弘, 羽場宏光, 豊嶋厚史, 深瀬浩一, 「211 At 標識 PSMA 誘導体による前立腺がん α 線核医学治療」, 第 5 回日本核医学会分科会放射性薬品科学研究会/第 21 回放射性医薬品・画像診断薬研究会, 福井市, 2022 年 9 月 17 日.
高橋浩之 (口頭発表), 島添健次, 関野正樹, 鎌田圭, 羽場宏光, 百瀬敏光, 「2 光子ガンマ線の多次元空間の相関を用いた高次イメー
ジング法の研究」, 2022 年第 83 回応用物理学会秋季学術講演会, 仙台市 & オンライン, 2022 年 9 月 20–23 日.
久下恒明 (口頭発表), 増田寛喜, 杜婉瑩, 保田智彦, 杉山暁, 羽場宏光, 巽俊文, 秋光信佳, 熊倉嘉貴, 吉田寛, 瀬戸泰之, 和田洋一郎,
野村幸世, 「胃癌腹膜播種モデルマウスを用いた腹膜播種に対する 211 At 標識抗 FGFR4 抗体による放射線免疫療法の検討」,第81 回日本癌学会学術総会, 横浜市, 2022 年 9 月 29 日–10 月 1 日.
高島大輝 (口頭発表), 大貫和信, 眞鍋史乃, 古賀宣勝, 津村遼, 安西高廣, 王洋, 殷小杰, 佐藤望, 重河優大, 南部明弘, 臼田祥子, 羽場
宏光, 藤井博史, 安永正浩, 「アスコルビン酸 Na は放射線分解による能動的標的化の障害からアスタチン-211 結合抗体を保護する」, 第 81 回日本癌学会学術総会, 横浜市, 2022 年 9 月 29 日–10 月 1 日.
重河優大 (招待講演), 「超低エネルギー励起核 U-235m と Th-229m の核壊変特性に関する研究」, 電気学会 2022 年度第 1 回調査専
門委員会, 文京区, 2022 年 10 月 28 日.
羽場宏光 (依頼講演), 「新元素でがん治療〜理研 RI ビームファクトリーがつくるラジオアイソトープ〜」, 放射線安全フォーラム
第 75 回放射線防護研究会「短寿命核種の利用の拡大に向けて」, 文京区 & オンライン, 2022 年 10 月 29 日.
藤野隼輔 (口頭発表), 森健一, 山田崇裕, 羽場宏光, Wang Yang, Yin Xiaojie, 南部明弘, 「211 At 固体線源作成手法の検討」, 第 4 回日
本保健物理学会・日本放射線安全管理学会合同大会, 福岡市, 2022 年 11 月 24–26 日.
横田望海 (口頭発表), 若狭智嗣, 西畑洸希, 岸本侃己, 米村千恵子, 笹野匡紀, 三木謙二郎, 今井伸明, 上坂友洋, 浦山廉, 大田晋輔, 亀谷
晃毅, 竹田浩之, 波多野雄治, 羽場宏光, 早水友洋, 原正憲, 道正新一郎, 他 RIBF-SHARAQ11 Collaboration, 「3 H(t, 3 He)3 n 反応による 3 中性子系探索に向けた中性子測定系の開発」, 第 128 回日本物理学会九州支部例会, 熊本市, 2022 年 12 月 3 日.
山口敦史 (招待講演), 重河優大, 羽場宏光, 和田道治, 香取秀俊, 「原子核時計実現にむけたトリウムイオンのトラップとレーザー
分光」, レーザー学会学術講演会第 43 回年次大会, 名古屋市, 2023 年 1 月 18–20 日.
重河優大 (口頭発表), 「Th-229m イオンの引き出しとイオントラップ実験の現状」, 2022 重元素化学研究会, あわら市, 2023 年 3 月
20 日–21 日.
田中聡 (口頭発表), 石川知輝, 河西壱輝, 岡本直大, 早水友洋, A. Kastberg, B. K. Sahoo, B. P. Das, 西野仁, 小野崇人, 羽場宏光, 東條賢, 酒見泰寛, 松尾由賀利, 鳥井寿夫, 青木貴稔, 「ダークマター探索のための Cs 原子の磁気光学トラップ」, 日本物理学会 2023
年春季大会, オンライン, 2023 年 3 月 22–25 日.
福永優太 (口頭発表), Kjeld Beeks, 藤本弘之, 平木貴宏, 管明, 羽場宏光, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 永澤延元, 岡井
晃一, 笹尾登, Fabian Schaden, Thorsten Schumm, 瀬戸誠, 重河優大, 高取沙悠理, 玉作賢治, 植竹智, 渡部司, 渡部信, 山口敦史, 安田
勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦, 「トリウム 229 アイソマー準位探索のための核共鳴散乱標的の開発」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
平木貴宏 (口頭発表), Kjeld Beeks, 藤本弘之, 福永優太, 管明, 羽場宏光, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 永澤延元, 岡井
晃一, 笹尾登, Fabian Schaden, Thorsten Schumm, 瀬戸誠, 重河優大, 高取沙悠理, 玉作賢治, 植竹智, 渡部司, 渡部信, 山口敦史, 安田
勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦, 「トリウム 229 アイソマー状態からの脱励起真空紫外光の探索」, 日本物理学会
2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
高取沙悠理 (口頭発表), Kjeld Beeks, 藤本弘之, 福永優太, 管明, 羽場宏光, 平木貴宏, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 永澤
延元, 岡井晃一, 笹尾登, Fabian Schaden, Thorsten Schumm, 瀬戸誠, 重河優大, 玉作賢治, 植竹智, 渡部司, 渡部信, 山口敦史, 安田
勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦, 「固体原子核時計の実現へ向けた放射光 X 線を用いたトリウム 229 結晶の特性評価」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
眞鍋史乃 (口頭発表), 高島大輝, 羽場宏光, 安永正浩, 藤井博史, 「有機化学・医学・核化学融合による α 線治療への試み」, 日本薬- 337 -

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学会第 143 年会, 札幌市, 2023 年 3 月 25–28 日.
山ノ内邑希 (ポスター発表), 坂口聡志, Pierre Brionnet for nSHE Collaboration, 「新元素合成のための最適反応エネルギー推定に向けた 51 V + 159 Tb 融合反応の励起関数測定」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
深津巧光 (ポスター発表), 坂口聡志, Pierre Brionnet for nSHE Collaboration, 「新元素合成のための最適反応エネルギー推定に向けた 51 V + 159 Tb 融合反応の障壁分布測定 I」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
道本優也 (ポスター発表), 坂口聡志, Pierre Brionnet for nSHE Collaboration, 「新元素合成のための最適反応エネルギー推定に向けた 51 V + 159 Tb 融合反応の障壁分布測定 II」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
上原大祐 (口頭発表), 長濱弘季, 中村圭佑, 佐藤幹, 中下輝士, 小澤直也, 永瀬慎太郎, 深瀬実来, 青木貴稔, 山口敦史, 高峰愛子, 上野
秀樹, 酒見泰寛, 「レーザー冷却フランシウム源実現に向けた金属表面における中性脱離反応の研究」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
深瀬実来 (口頭発表), 長濱弘季, 中村圭佑, 小澤直也, 佐藤幹, 中下輝士, 永瀬慎太郎, 上原大祐, 高峰愛子, 上野秀樹, 酒見泰寛, 「フランシウム原子の永久双極子能率探索に向けた高周波二重極質量フィルターの開発」, 日本物理学会 2023 年春季大会, オンライ
ン, 2023 年 3 月 22–25 日.
小澤直也 (口頭発表), 長濱弘季, 中村圭佑, 佐藤幹, 中下輝士, 永瀬慎太郎, 上原大祐, 深瀬実来, 青木貴稔, 山口敦史, 高峰愛子, 上野
秀樹, 酒見泰寛, 「永久電気双極子能率探索を目指した冷却フランシウム原子源の開発」, 日本物理学会 2023 年春季大会, オンラ
イン, 2023 年 3 月 22–25 日.

Press Release

難治性前立腺がんをアルファ線で攻撃—阪大発の治療薬を用いた医師主導治験の準備を開始—, 大阪大学, 理化学研究所, アルファフュージョン社, 2022 年 11 月 17 日, https://www.riken.jp/press/2022/20221117_2 .

Awards

羽場宏光, 「アルファ線核医学治療に向けたアスタチン-211 の大量製造技術の開発」, 2022 年度理研栄峰賞, 2023 年 3 月 22 日.
重河優大, 「Estimation of radiative half-life of 229m Th by half-life measurement of other nuclear excited states in 229 Th (229 Th 原子核の励起準位の半減期測定による 229m Th の γ 線放出半減期の推定)」, 第 14 回理研研究奨励賞 (桜舞賞), 2023 年 3 月 22 日.

Outreach Activities

羽場宏光 (依頼講演), 「新元素でがん治療—RIBF がつくるラジオアイソトープ—」, 理研と未来を創る会第 28 回講演会, 和光市,
2022 年 9 月 6 日.
羽場宏光 (依頼講演), 「ラジオアイソトープの製造を通じた産業振興」, シンポジウム「理化学研究所仁科研究室のキセキ」, 和光市& オンライン, 2022 年 10 月 28 日.
羽場宏光 (依頼講演), 「ニホニウム発見への道のり」, 山梨県立吉田高等学校理研見学会, 和光市, 2022 年 11 月 16 日.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

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

Support of industrial utilization of the RIBF accelerator beam.

3. Summary of Research Activity

RNC promote facility-sharing program “Promotion of applications of high-energy heavy ions and RI beams.” In this program,
RNC opens a part of the RIBF facility, which includes the AVF cyclotron, RIKEN Ring Cyclotron and experimental instruments,
to non-academic proposals from users including private companies. The proposals are reviewed by a program advisory committee,
industrial PAC (IN-PAC). The proposals which have been approved by the IN-PAC are allocated with beam times and the users pay
RIKEN the beam time fee. The intellectual properties obtained by the use of RIBF belong to the users. In order to encourage the useof RIBF by those who are not familiar with utilization of ion beams, the ﬁrst two beam times of each proposal can be assigned to trial
uses which are free of beam time fee.
In July 2022, the IN-PAC met and approved fee-based proposals from private companies; four proposals from new companies
and three proposals from continuously using companies. In January 2023, the IN-PAC held a mail review and approved ﬁve fee-based
proposals from continuous users. In 2022, ﬁve companies executed 15 fee-based beamtimes, ten of which utilized a Kr beam with a
total beam time of 146 hours, four utilized an Ar beam with a total beam time of 65 hours and one of which utilized a C beam with a
total beam time of 11 hours.

Members
Team Leader
Atsushi YOSHIDASpecial Temporary Technical Scientist
Kowashi WATANABE
Research Consultant
Tadashi KAMBARA

List of Publications & Presentations
Publication[Book]

吉田敦, 「2.2 応用研究 I—宇宙開発と加速器」, 量子ビーム科学の基礎と応用: 原子力システム研究懇話会 (NSA コメンタリーシ
リーズ), NSA/COMMENTARIES: No.27, pp. 40–45, ISBN978-4-88911-315-0.

Presentation[Seminar]

吉田敦, 「照射施設利用の効率化について〜理研・仁科加速器センターの取り組み〜」, 経産省: 放射線試験・ソフトエラー対策に関する勉強会 (第 10 回), オンライン, 2022 年 5 月 13 日.

Other
Fee-based beamtimes for private companies: Kr beam 146 hours, Ar beam 65 hours, C beam 1 hour; 222 hours in total.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Subnuclear System Research Division
Strangeness Nuclear Physics Laboratory
1. Abstract

Unlike many-body systems, few-body systems can be described with microscopic theories that can be solved without approximations. To this end the laboratory uses numerical techniques to exactly solve the equations describing few-body quantum systems. In
particular, an accurate calculation method called the ‘Gaussian Expansion Method using inﬁnitesimally shifted Gaussian lobe basis
function’ has been developed. This method makes calculations tractable up to ﬁve bodies even with complicated interactions. It has
been applied to various three-, four- and ﬁve-body calculations in hypernuclei, light nuclear systems, as well as cold-atom systems.
These calculations have provided new insights into these various ﬁelds of physics.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)

Structure of hypernuclei
Neutron-rich nuclei
Few-body universality in nuclear and atomic systems
Structure of exotic hadron system
Equation of state for neutron stars

3. Summary of Research Activity(1) Hypernuclei
We have investigated the role of hyperons in the structure of atomic nuclei. Using the antisymmetrized quasi-cluster model(AQCM), we investigated the role of up to two Λ hyperons in isotopes of Be and C. The presence of the Λ hyperons attract the αclusters to distances where the spin-orbit interaction can break the cluster structure. We found that while the reduction of the cluster
structure is signiﬁcant in C, it remains limited for Be. We have also proposed a new way to study the spin-isospin dependence of theΞN interaction by adding α particles in order to make a ΞN pair bound without altering its spin-isospin structure. The energy levels
were calculated by the Gaussian Expansion Method (GEM) using ab-initio ΞN potentials obtained from lattice QCD calculations. It
was found that the pair becomes bound in the presence of two α particles, leading to spin-doublet bound states in both the isospin
triplet and singlet channels. The calculation predicts that the spin-doublet energies are inverted when the isospin conﬁguration ischanged, revealing the isospin dependence of the ΞN interaction. We proposed to check these predictions in experiments involving K
mesons on 10 B targets to produce ΞNαα bound states.
(2) Neutron-rich nuclei
We have investigated the possible exis tence of a 7 H resonant state, by modelling this system as an eﬀective 3 H-n-n 5-body systemsolved with the GEM. We found no narrow resonance but a broad structure at ER ≈ 9 MeV above this threshold corresponding to the 7 H
ground state. In a separate work, we have devised a reaction model to describe the fast removal of the α-particle in 8 He nucleus leading
to the emission of 4 neutrons. Our model explains the energy peak observed in experiment as consequence of dineutron-dineutron
correlation rather than the existence of a hypothetical tetraneutron.
(3) Few-body universality
We have investigated the universal geometry of three-body halos made of loosely bound core and two particles, such as twoneutron halo nuclei. This geometry could be calculated analytically. It was found that in absence of resonance between the twoparticles, the size of the halo increases logarithmically with the inverse of the binding energy, but close to the resonance between thetwo particles, it becomes proportional to the inverse of the binding energy. These analytical universal properties were also shown
to apply to Eﬁmov states that are observable in cold-atom experiments. In a diﬀerent work, we looked at the speciﬁc case of the
two-neutron halo of 19 B, computing its properties numerically using the GEM and the Faddeev method. These calculations conﬁrmedthat its geometrical properties are model-independent.
(4) Exotic hadron systems
We have used chiral eﬀective theories of diquarks and quark-diquark to investigate doubly heavy tetraquarks Qq̄q̄ and singly
heavy baryons Qqq . We also used extended quark models to investigate the fully charmed tetraquark resonant states ccc̄c̄ as well as
p-wave BS states. From these calculations, we could reproduce some experimental data and make predictions for unobserved states.
In addition, we investigated the hadron mass spectrum of two-color QCD at ﬁnite density using the linear sigma model, as well as
lattice calculations. Other research activities include the study of SU(N) Yang-Mills theory and the Dirac Kondo eﬀect under magnetic
catalysis.
(5) Equation of state for neutron stars
To obtain the equation of state of neutron stars at the hadron-quark crossover we interpolated the relativistic mean-ﬁeld (RMF)
model and Nambu-Jona-Lasinio (NJL) model with an interpolation method that reduces randomness. In a diﬀerent work, we also
resolved the technical problem of spurious states appearing the numerical solutions of the Dirac equation solved with the ﬁnitediﬀerence method.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

Members
Director
Emiko HIYAMA
Senior Research Scientists
Takumi DOI

Pascal NAIDON

Contract Researcher
Etsuko ITOU
Special Postdoctoral Researchers
Tokuro FUKUIDaiki SUENAGA

Daisuke YOSHIDA

Postdoctoral Researchers
Lucas M.C. HAPP

Akira MATSUMOTO

Research Consultants
Shoji SHINMURA

Wolfram WEISE (TU Munich)Senior Visiting Scientist
Makoto OKA (JAEA)
Visiting Scientists
Masayuki ASAKAWA (Osaka Univ.)
Kadir Utku CAN (The Univ. of Adelaide)
Jaume CARBONELL (I’rene Joliot-Curie Lab.)
Akinobu DOTE (KEK)
Shimpei ENDO (Tohoku Univ.)
Tobias FREDERICO (Technological Inst. of Aeronautics)
Tomokazu FUKUDA (Univ. of Electro-Commun.)
Yasuro FUNAKI (Kanto Gakuin Univ.)
Takenori FURUMOTO (Yokohama Nat’l Univ.)
Philipp GUBLER (JAEA)
Satoru HIRENZAKI (Nara Women’s Univ.)
Atsushi HOSAKA (Osaka Univ.)
Jinniu HU (Nankai Univ.)
Tetsuo HYODO (Tokyo Metropolitan Univ.)
Yoichi IKEDA (Osaka Univ.)
Masahiro ISAKA (Hosei Univ.)
Souichi ISHIKAWA (Hosei Univ.)
Daisuke JIDO (Tokyo Tech)
Hyun-Chul KIM (Inha Univ.)
Toshio MOTOBA (Univ. of Electro-Commun.)Takayuki MYO (Osaka Inst. of Tech.)
Sho NAGAO (Univ. of Tokyo)
Satoshi NAKAMURA (Univ. of Tokyo)

Kazuma NAKAZAWA (Gifu Univ.)
Hidekatsu NEMURA (Kyoto Univ.)
Jean-Marc RICHARD (Lyon Univ.)
Thomas RIJKEN (Univ. Of Nijmegen)Shoichi SASAKI (Tohoku Univ.)Hans-Josef SCHULZE (INFN)
Tingting SUN (Zhengzhou Univ.)
Masanori TACHIKAWA (Yokohama City Univ.)
Hiroyuki TAJIMA (Univ. of Tokyo)
Masaaki TOKIEDA (The Nat’l Inst. for Res. in Computer Sci.
and Automation (INRIA))
Hui TONG (Tianjin Normal Univ.)
Atsushi UMEYA (Nippon Inst. of Tech.)
Shin WATANABE (NIT, Gifu College)
Chengjun XIA (Yangzhou Univ.)
Masanobu YAHIRO (Kyushu Univ.)
Ulugbek YAKHSHIEV (Inha Univ.)
Taiichi YAMADA (Kanto Gakuin Univ.)
Yasuo YAMAMOTO (Tsuru Univ.)
Nodoka YAMANAKA (Nagoya Univ.)
Takuma YAMASHITA (Tohoku Univ.)
Ying ZHANG (Tianjin Univ.)
Xian-Rong ZHOU (East China Normal Univ.)

Student Trainees
Moemi MATSUMOTO (Tohoku Univ.)

Shuhei OHNO (Yokohama City Univ.)

Administrative Part-time Worker
Yoko FUJITA

List of Publications & Presentations
Publications[Original Papers]
N. Itagaki and E. Hiyama, “Cluster-shell competition and eﬀect of adding hyperons,” Phys. Rev. C 107, 024309 (2023).
E. Hiyama, M. Isaka, T. Doi, and T. Hatsuda, “Probing the ΞN interaction through inversion of spin-doublets in ΞNαα nuclei,” Phys. Rev.
C 106, 064318 (2022).
E. Hiyama, R. Lazauskas, J. Carbonell, and T. Frederico, “Scaling of the 19 B two-neutron halo properties close to unitarity,” Phys. Rev. C
106, 064001(2022).

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RIKEN Accel. Prog. Rep. 56 (2023)

E. Hiyama, R. Lazauskas, and J. Carbonell, “7 H ground state as a 3 H + 4n resonance,” Phys. Lett. B 833, 137367 (2022).
S. Choi, E. Hiyama, C. -H. Hyun, and M. -K. Cheoun, “Eﬀects of many-body interactions in hypernuclei with Korea-IBS-Daegu-SKKU
functionals,” Eur. Phys. J. A 58, 8 (2022).
T. Yamashita, Y. Kino, E. Hiyama, S. Jonsell, and P. Froelich, “Near-threshold behavior of positronium-antihydrogen scattering crosssections,” Phys. Rev. A 105, 052812 (2022).
K. Murakami, Y. Akahoshi, S. Aoki, T. Doi, and K. Sasaki (HAL QCD Collaboration), “Lattice quantum chromodynamics (QCD) studies
on decuplet baryons as meson-baryon bound states in the HAL QCD method,” Prog. Theor. Exp. Phys. 2023, 043B05 (2023).
Y. Lyu, T. Doi, T. Hatsuda, Y. Ikeda, J. Meng, K. Sasaki, and T. Sugiura, “Attractive N-phi interaction and two-pion tail from lattice QCD
near physical point,” Phys. Rev. D 106, 074507 (2022).
Y. Lyu, H. Tong, T. Sugiura, S. Aoki, T. Doi, T. Hatsuda, J. Meng, and T. Miyamoto, “Optimized two-baryon operators in lattice QCD,”
Phys. Rev. D 105, 074512 (2022).
P. Naidon, L. Pricoupenko, and C. Schmickler, “Shallow trimers of two identical fermions and one particle in resonant regimes,” SciPost
Phys. 12, 185 (2022).
Z. Yang, G. J. Wang, J. J. Wu, M. Oka, and S. L. Zhu, “The investigations of the P-wave BS states combining quark model and lattice
QCD in the coupled channel framework,” J. High Energy Phys. 01, 058-1–19 (2023).
G. J. Wang, Q. Meng, and M. Oka, “The S-wave fully-charmed tetraquark resonant states,” Phys. Rev. D 106, 096005-1–9 (2022).
N. Yamanaka and M. Oka, “Weinberg operator contribution to the CP-odd nuclear force in the quark model,” Phys. Rev. D 106, 0750211–15 (2022).
Y. Kim, M. Oka, and K. Suzuki, “Doubly heavy tetraquarks in a chiral-diquark picture,” Phys. Rev. D 105, 074021-1–17 (2022).
Y. Kim, M. Oka, D. Suenaga, and K. Suzuki, “Strong decays of singly heavy baryons from a chiral eﬀective theory of diquarks,” Phys.
Rev. D 107, 074015 (2023).
D. Suenaga and M. Kitazawa, “Eﬀective model for pure Yang-Mills theory on T 2 × R2 with Polyakov loops,” Phys. Rev. D 107, 074502(2023).
D. Suenaga, K. Murakami, E. Itou, and K. Iida, “Probing the hadron mass spectrum in dense two-color QCD with the linear sigma model,”Phys. Rev. D 107, 054001 (2023).
M. Furushima, M. Takagi, D. Yoshida, Y. Kita, T. Shimazaki, and M. Tachikawa, “Theoretical investigations of positron aﬃnities andtheir structure-dependent properties of carbon dioxide clusters (CO2 )n (n = 1–5),” Phys. Chem. Chem. Phys. 25, 625 (2022).
D. Yoshida, Y. Kita, T. Shimazaki, and M. Tachikawa, “A comprehensive theoretical study of positron binding and annihilation properties
of hydrogen bonded binary molecular clusters,” Phys. Chem. Chem. Phys. 24, 26898 (2022).

[Proceedings]
T. Yamashita, E. Hiyama, K. Piszczatowski, S. Jonsell, and P. Froelich, “A four-body calculation of s-wave resonant scattering between
positronium and antihydrogen atom,” JJAP Conf. Proc. 9, 011002 (2023).
T. Doi, Y. Lyu, H. Tong, T. Sugiura, S. Aoki, T. Hatsuda, J. Meng, and T. Miyamoto, “Finite volume analysis on systematics of thederivative expansion in HAL QCD method,” PoS LATTICE 2021, 564 (2022).
Y. Lyu, H. Tong, T. Sugiura, S. Aoki, T. Doi, T. Hatsuda, J. Meng, and T. Miyamoto, “Most charming dibaryon near unitarity,” PoS
LATTICE 2021, 606 (2022).
T. Sugiura, Y. Akahoshi, T. Aoyama, T. M. Doi, and T. Doi, “Nuclear force with LapH smearing,” PoS LATTICE 2021, 565 (2022).
Y. Akahoshi, S. Aoki, and T. Doi, “Emergence of the rho resonance from the HAL QCD potential,” PoS LATTICE 2021, 625 (2022).
Y. Kamiya, K. Sasaki, T. Fukui, T. Hyodo, K. Morita, K. Ogata, A. Ohnishi, and T. Hatsuda, “Femtoscopic study on the ΛΛ-NΞ interaction,” Supl. Rev. Mex. Fis. 3, 0308124 (2022).
A. Ohnishi, Y. Kamiya, K. Sasaki, T. Fukui, T. Hyodo, K. Morita, K. Ogata, and T. Hatsuda, “Femtoscopic study of coupled-channel
baryon-baryon interactions with S = −2,” Proc. Sci. 380, 212 (2022).
K. Murakami, D. Suenaga, E. Itou, and K. Iida, “Measurement of hadron masses in 2-color ﬁnite density QCD,” PoS LATTICE 2022,
154 (2023).
D. Suenaga, “Roper-like singly heavy baryons in a chiral model,” Rev. Mex. Fis. Suppl. 3, 0308025 (2022).

Presentations[International Conferences/Workshops]
E. Hiyama (invited), “Structure of light Ξ hypernuclei and ΞN interaction,” 66th OMEG-SSANP Workshop, Seoul, Korea, February 22,
2023.
E. Hiyama (invited), “Structure of heavy hydrogen nucleus, 7 H with t + 4n cluster model,” Fudan Frontiers of Nuclear Physics Open
Forum, Online, January 11, 2023.
E. Hiyama (invited), “Structure of Ξ hypernuclei and ΞN interaction,” EMMI Workshop “Meson and Hyperon Interactions with Nuclei”
Kitzbühel, Austria, September 14–16, 2022.
E. Hiyama (invited), “The resonance of 7 H with t + 4n model,” Nuclear Physics at the Edge of Stability, Trento Italy, July 4–8, 2022.
E. Hiyama (invited), “Structure of light Ξ hypernuclei,” 14th International Conference on Hypernuclear and Strange Particle Physics(HYP2022), Prague, Czech Republic & Online, June 27–July 1, 2022.
T. Doi and G. Mantzaridis (invited), “pΩ and ΛΞ: experimental and theoretical overview,” workshop on Femtoscopy in high-energy
collisions at ALICE (FemTUM 2022), Munich, Germany & Online, August 31–September 2, 2022.

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RIKEN Accel. Prog. Rep. 56 (2023)

T. Doi for HAL QCD Collaboration (invited), “Nuclear physics from lattice QCD,” 15th Asia Paciﬁc Physics Conference (APPC15),
Seoul, Korea & Online, August 21–26, 2022.
T. Doi for HAL QCD Collaboration (invited), “Lattice QCD study of hadron interactions with strangeness,” 14th International Conference
on Hypernuclear and Strange Particle Physics (HYP2022), Prague, Czech & Online, June 27–July 1, 2022.
P. Naidon (invited), “Universal geometry of Borromean halo states,” The 3rd Japan-France Workshop “Few-body problems in Physics—
From atoms to quarks,” Tohoku University, Sendai, Japan, February 27–March 3, 2023.
P. Naidon (invited), “Few- and many-body physics of mass-imbalanced two-component systems,” Lecture at the programme “Living Near
Unitarity,” Kavli Institute for Theoretical Physics, UC Santa Barbara, Santa Barbara, U. S. A, May 12, 2022.
M. Oka, “Chiral eﬀective theory of diquarks and application to heavy hadron spectrum,” 14th International Conference on Hypernuclear
and Strange Particle Physics (HYP2022), Prague, Czech Republic & Online, June 27–July 1, 2022.
T. Fukui (oral), “Shell model study of chiral three-nucleon force,” Physics of RI: Recent Progress and Perspectives, RIKEN, Wako, Japan,
May 31–June 1, 2022.
T. Fukui (oral), “Shell model study of chiral three-nucleon force,” Developments of Physics of Unstable Nuclei (YKIS2022b), YITP,
Kyoto University, Kyoto, Japan, May 9 –June 17, 2022.
D. Suenaga (oral), “Modiﬁcations of diquark masses at ﬁnite density,” 3rd J-PARC HEF-ex WS, Tokai, Japan, March 14–16, 2023.
D. Suenaga (oral), “Phase structure of pure Yang-Mills theory in an anisotropic system: A new extreme condition of QCD” The 9thInternational Conference on Quarks and Nuclear Physics, Online, September 5–9, 2022.
D. Suenaga (oral), “Phase structure of pure Yang-Mills theory in an anisotropic system: A new extreme condition of QCD,” The XVthQuark Conﬁnement and the Hadron Spectrum Conference, University of Stavanger, Stavanger, Norway, August 1–6, 2022.
L. Happ (invited), “Universal eﬀects in one dimension,” The 3rd Japan-France Workshop “Few-body problems in Physics—From atoms
to quarks,” Sendai, Japan, February 27–March 3, 2023.

[Domestic Conferences/Workshops]

肥山詠美子 (招待講演), 「少数多体系物理からみたハイパー核の現在と将来」, 「ハイパー核研究の進展と未来〜格致日新〜」, 仙台
市 (東北大学), 2022 年 12 月 17 日.
肥山詠美子 (口頭発表), 「クラスター観点からみた軽い中性子過剰原子核とハイパー核の構造」, 大阪公立大研究会「原子核におけるクラスター物理の新展」, 大阪市 (大阪公立大学), 2022 年 10 月 19–20 日.
土井琢身 for HAL QCD collaboration (口頭発表), 「物理点 QCD 配位におけるバリオン間相互作用 (Strangeness = −4, 0) 」
, 日本物
理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
P. Naido (invited), “Mass-imbalanced two-component system,” 基研・iTHEMS 国内モレキュール型研究会 2022 「少数系の量子ダイナミクス」, 京都市 (京都大学基礎物理学研究所), 2022 年 8 月 22 日–26 日.
P. Naidon (invited), “Eﬁmov physics and low-energy universality in few-body systems,” The YONUPA Summer School, Online, August
7–9, 2022.
岡眞, “Fully-charmed tetraquark and quark conﬁnement,” ELPH 研究会 C033「ハドロン分光に迫る反応と構造の物理」, 仙台市 (ELPH),
2022 年 12 月 6–7 日.
M. Oka, D. Jido, G. J. Wang, 「マルチクォーク系のクォーク閉込めポテンシャル」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
福井徳朗（口頭発表）, 「カイラル相互作用による軽い核のクラスター構造の理解に向けて」, 大阪公立大研究会「原子核におけるクラスター物理の新展開」, 大阪市 (大阪公立大学), 2022 年 10 月 19–20 日.
T. Fukui (oral), L. Coraggio, G. De Gregorio, A. Gargano, N. Itaco, 「カイラル 3 体力のテンソル構造と軽い核のスピン軌道分離」, 日
本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
末永大輝 (口頭発表), “Mass modiﬁcations of diquarks in medium from chiral symmetry and anomaly,” J-PARC ハドロン研究会 2023,
オンライン, 2023 年 3 月 27–29 日.
末永大輝 (口頭発表), 「NJL 模型に基づいた有限密度系のダイクォークの性質変化」, 日本物理学会 2023 年春季大会, オンライン,
2023 年 3 月 22–25 日.
末永大輝 (口頭発表), “Modiﬁcations of diquark masses at ﬁnite density with chiral symmetry restoration,” RCNP workshop on Hadron
Physics at the LEPS2 photon beamline, 佐用郡 (SPring-8), 2023 年 3 月 6–7 日.
末永大輝 (招待講演), “Pentaquark picture for singly heavy baryons from chiral symmetry and anomaly,” Physics of heavy-quark andexotic hadrons 2023, 那珂郡 (J-PARC), 2023 年 1 月 30–31 日.
末永大輝 (口頭発表), 「カイラル対称性とアノマリーに着目したぺンタクォーク的ヘビーバリオンの性質」, ELPH 研究会 C033「ハドロン分光に迫る反応と構造の物理」, 仙台市 (ELPH), 2022 年 12 月 6–7 日.
末永大輝 (基調講演), 「非等方空間における pure Yang-Mills 理論の相構造: QCD の新しい極限環境としての非等方系」, 熱場の量子論 2022, 京都市 (京都大学基礎物理学研究所), 2022 年 9 月 20–22 日.
末永大輝 (口頭発表), 「線形シグマ模型を用いた 2 カラー QCD 物質中のハドロン質量変化」, 日本物理学会 2022 年秋季大会, 岡山
市 (岡山理科大学), 2022 年 9 月 6–8 日.
末永大輝 (口頭発表), 「QCD の新しい極限環境としての非等方ユークリッド空間」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
伊藤駿平, 吉田大輔, 北幸海, 島崎智実, 立川仁典 (口頭発表), 「量子モンテカルロ法を用いた分子ジアニオンの陽電子束縛に関する理論研究」, 第 16 回分子科学討論会, 横浜市 (慶應義塾大学), 2022 年 9 月 19–22 日.
伊藤駿平, 吉田大輔, 北幸海, 島崎智実, 立川仁典 (口頭発表), 「アニオン 2 量体の陽電子化合物に対する量子モンテカルロ法を用- 344 -

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いた第一原理理論研究」, 日本物理学会 2022 年秋季大会, 目黒区 (東京工業大学), 2022 年 9 月 12–15 日.
吉田大輔, 北幸海, 島崎智実, 立川仁典 (口頭発表), 「2 成分水素結合クラスターにおける陽電子束縛及び対消滅機構に関する理論研究」, 第 24 回理論化学討論会, 金沢市 (金沢商工会議所), 2022 年 5 月 17–20 日.
L. Happ (invited), “Universality in one-dimensional quantum three-body systems,” Mini-workshop on ultracold-atom theory, Wako-shi,
Japan, November 22, 2022.

[Seminars]
T. Doi, “Hybrid quantum annealing via molecular dynamics,” Seminar at RIKEN R-CCS, Online, Wako, Japan, June 14, 2022.
T. Doi, “Nuclear physics from lattice QCD,” Seminar at KMI Colloquium, Online, Nagoya University, Nagoya, Japan, June 8, 2022.
P. Naidon (invited), “Universal few-body clusters of heavy and light particles,” seminar at Institut Pluridisciplinaire Hubert Curien,
CNRS/Université de Strasbourg, Strasbourg, France, December 13, 2022.
P. Naidon (invited), “Miscibility and Polaron physics in two-component BEC,” Seminar at CESQ, Université de Strasbourg, Strasbourg,
France, December 7, 2022.
P. Naidon, “Mass-imbalanced two-component system,” “Mini-workshop on ultracold-atom theory,” RIKEN, Wako, Japan, November 22,
2022.
T. Fukui, “Theoretical study of three-nucleon force,” GPPU Seminar, Graduate Program on Physics for the Universe, Tohoku University,
Sendai, Japan, July 15, 2022.
D. Suenaga, “Heavy-quark spin polarization induced by the Kondo eﬀect in a magnetic ﬁeld,” QCD theory seminar, Online, January 16,
2023.
末永大輝, “Continuous transformation from hadrons to quarks in medium by means of a quark model,” 文京区 (東京大学), 2022 年 11
月 11 日.
D. Suenaga, “Singly heavy baryons from chiral symmetry,” Asia Paciﬁc Center for Theoretical Physics, Korea, June 23, 2022.
末永大輝, “Heavy-quark spin polarization induced by the Kondo eﬀect in a magnetic ﬁeld,” 京都市 (京都大学基礎物理学研究所), 2022
年 6 月 3 日.
末永大輝, “Singly heavy baryons from chiral symmetry,” 目黒区 (東京工業大学), 2022 年 5 月 16 日.

Award
T. Fukui, Presentation Award of FY2022 SPDR Presentation of Research Results, RIKEN, January 18, 2023.

OthersP. Naidon: Chairman at the International Symposium on Clustering as a Window on the Hierarchical Structure of Quantum Systems(CLUSHIQ2022), Sendai International Center, Sendai, October 31–November 3, 2022.
T. Fukui: RIKEN Wako Open Campus 2022, RIKEN, Saitama, Japan, April 23, 2022.

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Subnuclear System Research Division
Meson Science Laboratory
1. Abstract

Particles like muons, pions, and kaons have ﬁnite lifetimes, 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 use muonic atoms for proton magnetic radius measurement,muon catalyzed fusion and elemental analysis with muonic X-rays. 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 theseexperiments, we are studying the KN − interaction, and clarify the nature of kaon in nuclei. At Spring-8 and at GSI, we are planning tostudy omega and η1 nuclei. By these experiments, we aim to be a world-leading scientiﬁc research group using these light meta-stableparticles.
(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 completed to observe the “K − pp” bound state by the in-ﬂight 3 He(K − , n) reaction, which allows us
the formation via the invariant-mass spectroscopy by detecting decay particles from “K − pp.” For the experiment, we constructed a
dedicated spectrometer system at the secondary beam-line, K1.8BR, in the hadron hall of J-PARC.
With the Λpn ﬁnal states obtained in the ﬁrst stage experiment, we observed a kinematic anomaly in the Λp invariant mass
near the mass threshold of M(K − -pp) (total mass of kaon and two protons) at the lower momentum transfer q region. We conducteda successive experiment to examine the nature of the observed kinematical anomaly in the Λpn ﬁnal state, and we conﬁrmed theexistence of the bound state below the mass threshold of M(K − pp) at as deep as the binding energy of 40 MeV. The momentum
transfer q naturally prefers lower momentum for the bound state formation, but the observed event concentration extended having theform-factor parameter ∼400 MeV/c. Based on the PWIA calculation, the data indicated that the “K − pp” system could be as small as∼0.6 fm. It is astonishingly compact in contrast to the mean nucleon distance ∼1.8 fm.
This observed signal shows that a meson (qq− ) forms a quantum state where baryons (qqq) exist as nuclear medium, i.e., ahighly excited novel form of nucleus with a kaon, in which the mesonic degree-of-freedom still holds. This is totally new form of
nuclear system, which never been observed before.
(1-2) Precision X-ray measurement of kaonic atom
To study the 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,- 346 -

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RIKEN Accel. Prog. Rep. 56 (2023)

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 energies were determined to be 6224.5 +/ 0.4 (stat) +/ 0.2 (syst) eV and 6463.7+/ 0.3 (stat) +/ 0.1 (syst) eV, and widths to be 2.5 +/ 1.0 (stat) +/ 0.4 (syst) eV and 1.0 +/ 0.6 (stat) +/ 0.3 (syst) eV, for kaonic 3 He and4
He, respectively. These values are nearly 10 times more precise than in previous measurements. The results exclude the large stronginteraction shifts and widths that are suggested by a coupled-channel approach and agree with calculations based on optical-potential
models.
Another important X-ray measurement of kaonic atom would be 2p → 1 stransition 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 K bar 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 η1 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 provided high-precision data and set constraints on the pion-nucleus strong interaction, which led to deductionof the chiral condensate at the normal nuclear density. In 2021, systematic high precision spectroscopy of pionic Sn atoms were
performed and the analysis is ongoing.
We are also working on spectroscopy of η1 mesonic nuclei in GSI/FAIR. Theoretically, peculiarly large mass of η1 is attributed
to UA (1) symmetry and chiral symmetry breaking. As a result, large binding energy is expected for η1 meson bound states in nuclei(η1 -mesonic nuclei). From the measurement, we can access information about gluon dynamics in the vacuum via the binding energy
and decay width of η1 -nuclear bound state. In 2022, we performed a new experiment using a large solid angle detector of WASA at
GSI to search for the η1 -nucleus bound state with an enhanced signal-to-noise ratio.
(1-4) 3Λ H3, 4 H lifetime puzzle and our approach
Three recent heavy ion experiments (HypHI, STAR, and ALICE) announced surprisingly short lifetime for 3Λ H hyper-nucleus’s
Mesonic Weak Decay (MWD), which seems to be inconsistent with the fact that the 3Λ H is a very loosely bound system. It is very
interesting to study this with a diﬀerent experimental approach. We proposed a direct measurement of Λ H MWD lifetime withresolution at J-PARC hadron facility by using K-meson beam at 1 GeV/c. As for the feasibility test, we also measure 4Λ H lifetime.
A Cylindrical Detector System (CDS) used in J-PARC E15/E31 experiment is employed to capture the delayed π− as a weak decay
40
product from 3,
Λ H a calorimeter is installed in the very forward region to tag fast π meson emission at ∼0 degree, which ensures that4
the Λ hyperon production with small recoil momentum. By this selection, we can improve the ratio between 3,
Λ H and quasi-free Λ and4
Σ background. A test beam for feasibility study with He target has been conditionally approved by J-PARC PAC. We will conduct
the experiment and to present the data in short.
(1-5) Study of properties of vector mesons in nuclei
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 through the dielectron
decay channel, in order to explore the physics of chiral symmetry breaking and restoration in dense nuclear matter.
In JFY 2020, a new primary beam line for E16 was completed in J-PARC. Commissioning runs of the beam line and of ourspectrometer were performed. The detectors almost satisﬁed the design performance. Unexpected beam micro structures which
deteriorates the DAQ performance were found, and countermeasures were proposed. They will be applied in the test beam time,
which is planned in 2023. Based on the result, approval of physics beam time will be discussed in PAC held in Winter 2023–24.
This activity was moved to Meson Science Laboratory after the closing of Radiation Laboratory.
(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
We share experimental equipment with those of RAL in order to make organization of RIKEN beam time schedules easier andto enhance the eﬃciency to carry out RIKEN’s experiments. We use shared cryostats and manpower supports available from RAL
as well we other experimental areas. Both two µSR spectrometers, ARGUS (Port-2) and CHRNUS (Port-4), are working well withmaintenance supports provide from RAL. Among our scientiﬁc activities on µSR studies from year 2017 to 2022, following studies
are most important subjects of material sciences at the RIKEN-RAL muon facility:(1) Multi magnetic transitions in the Ru-based pyrochlore systems, R2 Ru2 O7 ;(2) Magnetic properties of the nano-cluster gold in the border of macro- and micro- scale;- 347 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)(3) Novel magnetic and superconducting properties of nano-size La-based high-TC superconducting curates;(4) Novel superconducting properties in quasi two-dimensional organic molecular systems.
(5) Determination of muon positions estimated from density functional theory (DFT) and dipole-ﬁeld calculations;(6) Chemical muonic states in DNA molecules.
(2-2) Nuclear and particle physics studies via ultra-cold muon beam and muonic atoms
If we can improve muon beam emittance, timing and energy dispersion (so-called “ultra-cold muon”), then the capability of µSR
studies will be drastically improved. The ultra-cold muon beam can stop in a thin foil, multi-layered materials and artiﬁcial lattices, so
one can apply the µSR techniques to surface and interface science. The development of ultra-cold muon beam is also very importantas the source of pencil-like small emittance muon beam for muon g − 2 measurement. Ultra-cold muon beam has been produced bylaser ionization of muoniums in vacuum (bound system of µ+ and electron). We developed a very promising materials for muonium
production, laser ablated silica aerogel. 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 crystals Nd:YGAG and Nd:YSAG, which has an ideal wavelength
property for laser ampliﬁcation to generate Lyman-α by four-wave mixing in Kr gas cell. We are now building the actual muon source
to be used for muon g-2. The ﬁrst part of the muon ionization chamber was manufactured and is being tested using the muon beam at
J-PARC.
(3) QED study of the lepton g-2
We are conducting research on Quantum Electrodynamics (QED) theory related to the determination of the theoretical and experimental values of the lepton anomalous magnetic moment (g-2). The contribution of QED to g-2 can be obtained through perturbative
calculations using Feynman diagrams. We are carrying out both analytical validation and numerical computation improvements todetermine the value of the 10th-order perturbation term. Additionally, we are also investigating the quantum corrections by QED to
the experimental determination formula of the electron g-2.

Members
Director
Masahiko IWASAKI
Senior Research Scientists
Kenta ITAHASHI
Yue MA
Haruhiko OUTA

Fuminori SAKUMA
Isao WATANABE
Satoshi YOKKAICHI

Senior Scientist
Makiko NIO
Contract Researchers
Katsuhiko ISHIDA

Tomonori TAKAHASHI

Special Postdoctoral Researcher
Koki KANNO
Postdoctoral Researchers
Koki KANNO

Rie MURAYAMA

Junior Research Associate
Tomoki MURAKAMIInternational Program Associates
Supparat CHAROENPHON (Kasetsart Univ.)
Muhammad H.B. CHE LAH (Univ. Sains Malaysia)

Li DENG (The Univ. of Sci. and Tech. of China)
Anita E. PUTRI (Univ. of Indonesia)

Research Consultant
Masayasu KAMIMURA
Senior Visiting Scientists
Hiroyuki NOUMI (Osaka Univ.)

Kazuhiro TANAKA (KEK)

Visiting Scientists
Tadashi ADACHI (Sophia Univ.)
Kazuya AOKI (KEK)
Tatsumi AOYAMA (KEK)
Retno ASIH (Inst. Teknologi Sepuluh Nopember)
Fahmi ASTUTI (Inst. Teknologi Sepuluh Nopember)

Wen-Chen CHANG (Inst. of Phys., Academia Sinica)
Catalina Oana CURCEANU (INFN)
Zyun EZAWA (Tohoku Univ.)
Hiroyuki FUJIOKA (Tokyo Tech)
Masaki FUJITA (Tohoku Univ.)- 348 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Shuhei FUKUOKA (Hokkaido Univ.)
Takayuki GOTO (Sophia Univ.)
Masashi HAYAKAWA (Nagoya Univ.)
Wataru HIGEMOTO (JAEA)
Ko-ichi HIRAKI (Fukushima Medical Univ.)
Satoru HIRENZAKI (Nara Women’s Univ.)
Koichi ICHIMURA (Hokkaido Univ.)
Yasuyuki ISHII (Shibaura Inst. of Tech.)
Ryosuke KADONO (KEK)
Takayuki KAWAMATA (Tokyo Denki Univ.)
Seiko KAWAMURA (JAEA)
Hikomitsu KIKUCHI (Univ. of Fukui)
Takuya KOBAYASHI (Saitama Univ.)
Yoji KOIKE (Tohoku Univ.)
Kenji MATSUDA (Univ. of Toyama)
Hiroyasu MATSUURA (Univ. of Tokyo)
Mototsugu MIHARA (Osaka Univ.)
Takaaki MINAMIDATE (Tokyo Univ. Sci)
Yasuhiro MIYAKE (KEK)
Yuhei MORINO (KEK)
Wataru NAKAI (KEK)
Takehito NAKANO (Ibaraki Univ.)
Takahiro NAMIKI (Univ. of Toyama)
Megumi NARUKI (Kyoto Univ.)
Katsuhiko NISHIMURA (Univ. of Toyama)
Agustinus NUGROHO (Inst. Teknologi Bandung)

Kazuki OHISHI (Comprehensive Res. Org. for Sci. and Soc.)
Yu OISHI (KEK)
Kyoichiro OZAWA (KEK)
Dita PUSPITA SARI (Shibaura Inst. of Tech.)
Muhammad R. RAMADHAN (Univ. Pertahanan Republik Indonesia)
Irwan RAMLI (Univ. Cokroaminoto Palopo)
RISDIANA (Padjadjaran Univ.)
Lusi SAFRIANI (Padjadjaran Univ.)
Naohito SAITO (KEK)
Shinichi SHAMOTO (Comprehensive Res. Org. for Sci. and
Soc.)
Ichiro SHIRAKI (Univ. of Yamanashi)
Shukri SULAIMAN (Univ. Sains Malaysia)
Takao SUZUKI (Shibaura Inst. of Tech.)Takanori TANIGUCHI (Tohoku Univ.)
Andrea VACCHI (Udine Univ. (Italy))
Eberhard WIDMANN (Stefan Meyer Inst.)
Yasuhiro YAMAGUCHI (Nagoya Univ.)
Ichihiro YAMAUCHI (Saga Univ.)
Yukio YASUI (Meiji Univ.)
Masaru YOSOI (Osaka Univ.)
Wan Nurfadhilah B. ZAHARIM (UNIVERSITI SAINSMALAYSIA)
Xu-Guang ZHENG (Saga Univ.)
Johann ZMESKAL (Austrian Academy of Sci.)

Visiting Technician
Che-Sheng LIN (Academia Sinica)
Research Fellow
Harison B. ROZAK (Shibaura Inst. of Tech.)Student Trainees
Tomoya ASANO (Saitama Univ.)
Masaya ICHIKAWA (Kyoto Univ.)
Shota MATSUMOTO (Kyoto Univ.)
Shunnosuke NAGAFUSA (Kyoto Univ.)
Satomi NAKASUGA (Kyoto Univ.)

Shuta OCHIAI (Kyoto Univ.)
Po-Hung WANG (Nat’l Central Univ.)
Utami WIDYAISWARI (Univ. Indonesia)
Kanako YAMAGUCHI (Kyoto Univ.)
Ryota YAMAZAKI (Saitama Univ.)

Research Part-time Worker
Utami WIDYAISWARI
Assistants
Kumiko TAKAHASHI

Mitsue YAMAMOTO

List of Publications & Presentations
Publications[Original Papers]
A. Jamaludin et al., “Density functional theory investigation of muon hyperﬁne interaction in guanine-cytosine double-strand DNA,” J.
Phys. Soc. Jpn. 91, 024301 (2022).
M. Redo Ramadhan et al., “Estimation of the on-site coulomb potential and covalent state in La2 CuO4 by muon spin rotation and density
functional theory calculations,” Phys. Rev. Res. 4, 033044 (2022).
A. Ito et al., “Antiferromagnetic ordering of organic mott insulator λ-(BEDSe-TTF)2 GaCl4 ,” Phys. Rev. B 106, 045114 (2022).
W. N. Zaharim et al., “Density functional theory study of muon hyperﬁne interactions in 12 mer single-strand adenine, cytosine, andthymine oligomers,” J. Phys. Soc. Jpn. 91, 094301 (2022).
T. Takayama et al., “Competing spin-orbital singlet states in the 4d4 honeycomb ruthenate Ag3 LiRu2 O6 ,” Phys. Rev. Res. 4, 043079(2022).
M. Cataldo et al., “A novel non-destructive technique for cultural heritage: Depth proﬁling and elemental analysis underneath the surface
with negative muons,” J. Phys. Soc. Jpn. 91, 024301 (2022).

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RIKEN Accel. Prog. Rep. 56 (2023)

C. Zhang et al., “Modeling the diﬀusion of muonium in silica aerogel and its application to a novel design of multi-layer target for thermalmuon generation,” Nucl. Instrum. Methods Phys. Res. A 1042, 167443 (2022).
G. A. Green et al., “Negative muons reveal the economic chaos of rome’s AD 68/9 civil wars,” Archaeol. Anthropol. Sci. 14, 165 (2022).
J-PARC E31 Collaboration, “Pole position of Λ (1405) measured in d(K − , n)π Σ reactions,” Phys. Lett. B 837, 137637 (2023).
T. Nishi et al., piAF Collaboration, “Chiral symmetry restoration at high matter density observed in pionic atoms,” Nat. Phys. 19, 788(2023).
N. Ikeno et al., “Pion-nucleon sigma term σπN and deeply bound pionic atoms,” Prog. Theor. Exp. Phys. 2023, 033D03 (2023).

[Books]A. D. Hillier et al., “Depth-dependent bulk elemental analysis using negative muons,” in Handbook of Cultural Heritage Analysis, S.
D’Amico and V. Venuti (eds.), Springer 2022, pp. 23–44.
K. Itahashi, “Pionic Atoms in Experiment,” in Handbook of Nuclear Physics, I. Tanihata, H. Toki, and T. Kajino, (eds.), Springer,
Singapore, https://doi.org/10.1007/978-981-15-8818-1_36-1 .

[Proceedings]
Y. Ma et al., “Status of J-PARC E73 experiment: ﬁrst direct Hypertriton lifetime measurement with 3 He(K − ,pi0)H3 L reaction,” Suplemento de la Revista Mexicana de Fisica 30308120, 1 (2022).
F. Sakuma et al., “J-PARC hadron experimental facility extension project,” EPJ Web Conf. 271, 11001 (2022).
F. Sakuma et al., “Summary of the K − pp bound-state observation in E15 and future prospects,” EPJ Web Conf. 262, 01008 (2022).
S. Nakasuga et al., “Commissioning of the electron identiﬁcation system for Dilepton measurement in pA collisions at J-PARC,” Nucl.
Instrum. Methods Phys. Res. A 1041, 167335 (2022).
K. Ozawa et al., “Towards the measurement of the mass modiﬁcations of vector mesons in a ﬁnite density matter,” Acta Phys. Pol. A 142,399 (2022).
M. Ichikawa et al., “Commissioning runs of J-PARC E16 experiment,” Acta Phys. Pol. B Proc. Suppl. 16, 1-A143 (2023).
K. Ozawa et al., “J-PARC heavy ion project,” EPJ Web Conf. 271, 11004 (2022).
Ce Zhang, T. Hiraki, K. Ishida, S. Kamal, S. Kamioka, T. Mibe, A. Olin, N. Saito, K. Suzuki, S. Uetake, and Y. Mao, “Modeling thediﬀusion of muonium in silica aerogel and its application to a novel design of multi-layer target for thermal muon generation,” Nucl.
Instrum. Methods Phys. Res. A 1042, 167443G (2022).

Presentations[International Conferences/Workshops]
T. Yamaga (invited), “Kaonic nuclei at J-PARC,” Third International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (3rd J-PARC HEF-ex WS), J-PARC, March 14–16, 2023.
T. Hashimoto (invited), “Experimental study of the four-body kaonic nuclear state, KbarNNN,” EXOTICO: EXOTIc Atoms Meet Nuclear
Collisions for a New Frontier Precision Era in Low Energy Strangeness Nuclear Physics ECT*, Trento, Italy, October 17, 2022.
T. Yamaga (invited), “Result of KbaRNN search at J-PARC and future projects,” EXOTICO: EXOTIc Atoms Meet Nuclear Collisions fora New Frontier Precision Era in Low Energy Strangeness Nuclear Physics ECT*, October 17, 2022.
T. Yamaga (invited), “Experimental investigation of KbarNN state using K − + 3 He reaction at J-PARC,” EMMI workshop, “Meson andhyperon interactions with nuclei,” Kitzbuhel, Austria, September 14–16, 2022.
M. Iwasaki (invited), “Kbar nuclear bound state—Toward revolutionary Nuclear Study via revealing Internal Structure of Kaonic Nuclei,”
The 28th International Nuclear Physics Conference (INPC 2022), Cape Town, South Africa, September 11–16, 2022.
T. Yamaga (invited), “Experimental study of KbarNN and future Kbar-nuclei experiments at J-PARC,” The 9th International Conferenceon Quarks and Nuclear Physics (QNP2022), Online, September 5–9, 2022.
T. Hashimoto (invited), “Experimental study of kaonic nuclei and kaonic atoms at J-PARC,” the 15th Asia Paciﬁc Physics Conference(APPC15), South Korea, August 21–26, 2022.
F. Sakuma (invited), “J-PARC hadron hall extension project,” 14th International Conference on Hypernuclear and Strange Particle Physics- HYP2022, Prague, Czech Republic, June 27–July 1, 2022.
T. Yamaga (invited), “Experimental study of KbarNN and future experiments for kaonic nuclei,” 14th International Conference on Hypernuclear and Strange Particle Physics - HYP2022, Prague, Czech Republic, June 27–July 1, 2022,
Y. Ma (invited), “Current status of hypertriton lifetime measurement with J-PARC E73 experiment,” 14th International Conference onHypernuclear and Strange Particle Physics - HYP2022, Prague, Czech Republic, June 27–July 1, 2022.
T. Hashimoto (oral), “Search for the KbarNNN bound state in the Λ dn ﬁnal states of the in-ﬂight K- reaction on 4 He,” 14th International
Conference on Hypernuclear and Strange Particle Physics - HYP2022, Prague, Czech Republic, June 27–July 1, 2022.
K. Kanno (oral), “Commissioning of a hadron blind detector for dielectron measurement in pA reactions at J-PARC,” MPGD2022,
Weizmann Institute, Rehovot, Israel/Hybrid, December 11–16, 2022.
S. Yokkaichi (invited), “Measurements of spectral change of vector mesons in nuclear matter at ﬁnite density,” Third International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility, J-PARC, Tokai, Japan & Online, March 14–16, 2023.
K. Ishida on behalf of the J-PARC muon g-2/EDM Collaboration (E34), “Muon g-2/EDM experiment at J-PARC,” Fifth Plenary Workshopof the Muon g-2 Theory Initiative, Edinburgh, September 5–9, 2022.
K. Itahashi (invited), “What ca npionic atoms tell about the QCD vacuum,” XVth Quark conﬁnement and the hadron spectrum, Stavanger,- 350 -

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August 1–6, 2022.
K. Itahashi (invited), “Pionic atoms and chiral symmetry,” 4th Jagiellonian Symposium, Krakow, July, 2022.

[Domestic Conferences/Workshops]

山我拓巳 (招待講演), “Study of mesonic decay of KNN and perspectives of kaonic nuclei experiments at J-PARC,” J-PARC ハドロン研究会, 東海村 (KEK), 2023 年 3 月 27–29 日.
橋本直 (招待講演), 「J-PARC における K 中間子原子核研究の状況と展望」, ELPH 研究会 C033「ハドロン分光に迫る反応と構造の物理」, 仙台市 (東北大学電子光理学研究センター), 2022 年 12 月 6–7 日.
高橋智則 (口頭発表), 「J-PARC E16 実験の DAQ の現状と課題」, RCNP 研究会「原子核実験の次世代データ収集システム基盤開発にむけて」, 茨木市 (RCNP) & オンライン, 2022 年 5 月 16–17 日.
T. N. Takahashi (招待講演), “Development of continuous readout electronics for precise measurement of dielectron spectra at J-PARC,”
第 8 回クラスター階層領域研究会, 大阪大学 & オンライン, 2023 年 2 月 9–11 日.
石田勝彦, 「ラザフォードアップルトン研究所ミュオン施設の紹介」, 第 7 回文理融合シンポジウム 量子ビームで歴史を探る—加速器が紡ぐ文理融合の地平—, つくば市 (KEK), 2022 年 11 月 3 日.
石田勝彦, 「ミュオン触媒核融合の利用」, 中間子科学の将来討論会, 和光市 (理研), 2022 年 11 月 9–11 日.
石田勝彦, 「理研 RAL 施設と原子・原子核研究」, 第 13 回 muon 科学と加速器研究研究会, 和光市 (理研), 2023 年 1 月 10–11 日.

[Seminar]

四日市悟, 「J-PARC E16 実験の現状と展望」, 第 14 回 J-PARC-HI の物理を語る夕べ (セミナーシリーズ), オンライン, 2022 年 8 月
19 日.

Press Releases「K 中間子と陽子が織りなす風変わりなバリオンを測定」, 大阪大学核物理研究センター, 高エネルギー加速器研究機構, J-PARC センター, 理化学研究所, 日本原子力開発機構, 東北大学電子光理学研究センター, INFN-LNF, SMI 共同プレスリリース, 2023 年 1
月 26 日.
「π で探る真空の秘密」, 理化学研究所, 奈良女子大, 鳥取大学, 阪大核物理研究センター, 共同プレスリリース, 2023 年 3 月 27 日.

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Subnuclear System Research Division
RHIC Physics Research Laboratory
1. Abstract

RHIC Physics Research laboratory study the strong interaction with PHENIX and sPHENIX experiment at RHIC collider in
Brookhaven National Laboratory in the U.S.A. This laboratory is formed in 2022 to be the RIKEN base of RIKEN BNL ResearchCenter after the Radiation Laboratory was closed. The two physics goals of RHIC are (1) to study quark-gluon plasma produced inheavy ion collisions and (2) to study the spin structure of the proton. The second physics program has been promoted by RIKEN’sleadership.
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. RIKEN group has played a leading role in the study of QGP. In particular we achieved theﬁrst observation of thermal photons from QGP and estimated its initial temperature. The temperature is approximately 350 MeV, well
above the transition temperature to QGP (∼160 MeV).
The original goals of RHIC spin program are to measure the gluon spin contribution to the proton and to measure ani-quark
polarization with the W → e and W → µ measurement. rsults from PHENIX π0 measurement and STAR jet measurement has shownthat gluons in the proton carry about 30% of the proton spin. This is a major milestone of the RHIC spin program. The ﬁnal resultsof W → e measurement was published in 2016 and the ﬁnal results of W → µ was published in 2018. The focus of the RHIC spin
program is moved to study of transverse spin measurement.
PHENIX completed its data taking in 2016 to be upgraded a new experiment and detector, sPHENIX. sPHENIX will measure
jets, photons, and Upsilon particles and will complete the scientiﬁc mission of RHIC. We constructed a intermediate-silicon tracker
INTT for sPHENIX. INTT was completed in 2022 and it was installed in sPHENIX in March 2023. The sPHENIX will start taking
data in 2023.

2. Major Research Subjects(1) Experimental Studies of the Spin Structure of the Nucleon(2) Study of Quark-Gluon Plasma at RHIC
(3) sPHENIX INTT detector

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. Y. Akiba (Laboratory Director) is the Spokesperson of PHENIX experiment since 2016.
Research Activity of this laboratory has large overlap with that of RBRC Experimental group since this laboratory is the RIKEN
Wako campus base of RBRC. In the below, recent results reported in the report of RBRC experimental group is excluded.
(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 gluon spin. PHENIX measured the parity-violating single spin
asymmetry AL of the W boson production in p + p in wide rapidity range. The results of the W boson measurements were publishedin 2016 and 2018, and these results give constraints on the anti-quark polarization in the proton. The focus of the spin physics is now
moved to the measurements of the single transverse spin asymmetry AN .
In 2017, an electromagnetic calorimeter RHICf detector was installed in the most forward area of the STAR experiment to obtainpolarized proton collision data for neutral particle production (neutrons, photons, neutral pions) as the RHICf experiment. In addition
to the already obtained asymmetry of neutral pions, the analyses of the production cross section of photons and asymmetry of neutrons
were almost completed and presented at international conferences and workshops. The photon production cross sections are comparedwith results from proton collisions at higher energies at the CERN-LHC, and the results support a scaling law that is independent ofcollision energy. These results provide new data necessary for the development of event generation codes to reproduce ultra-highenergy cosmic ray collision events with the atmosphere. The data analysis of high statistics for neutron asymmetries has yielded
results that cover a wide transverse momentum region with the expected high resolution, and the data are very interesting, showing
large asymmetries. A theoretical study is also being conducted to investigate the origin of these asymmetries, and comparisons with

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experimental data are being made. The ﬁnal results of both studies are being prepared for publication.
It is aiming to obtain physics data in 2024 to further elucidate the neutral production cross sections and asymmetries discoveredby the RHICf experiment. Although this experiment has not yet been approved, it will use silicon detector technology developed in the
ALICE-FoCal upgrade project at the LHC to introduce a larger detector with higher position resolution. Therefore, the collaboration
with ALICE has been resumed as an associated member and the detector is being jointly developed with the FoCal group. The
development of this new detector technology is also part of an essential R&D program for a zero-degree calorimeter (ZDC) detector
for EIC. As a result of the fabrication of a prototype detector, its testing and evaluation in the laboratory, test beams at the ELPH
facility at Tohoku University and the CERN-PS and SPS accelerators, and radiation tolerance tests at the RIKEN RANS neutron
irradiation facility, the selection of silicon detector technology for the actual detector was almost completed and the next stage of
detector fabrication is about to begin.
(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.
PHENIX completed its data taking after the 2016 run. We continue data analysis of PHENIX data. Recent highlights of study of
QGP by PHENIX is presented in the report by RBRC experimental group.
(3) sPHENIX INTT detector
We constructed intermediate silicon tracker INTT for sPHENIX, a new experiment at RHIC that will start taking data in 2023.
The INTT detector consists of 56 ladders, which are arranged to two layers of barrels. A ladder is shown in Fig. 1. It is a basic building
block of the INTT.

Fig. 1. Left: Completed two halves of INTT detector with members of INTT teams. Right: INTT detector and INTT team just after installation to sPHENIX.

Fig. 2. INTT collaboration.

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In the development of INTT, the ﬁrst step was to make a prototype of one ladder of INTT. The performance of the prototype wasthen evaluated to conﬁrm that it meets the required performance. If not, improvements were made. After this process was repeated
and the ladder prototype meets the required performance, mass production of the ladder started. In this development process process
was done by an international collaboration of INTT detector group led by Dr. Nakagawa of this laboratory and Dr. Rachid Nouicer of
Brookhaven National Laboratory. The collaboration is shown in Fig. 2.
In the fall of 2022, the construction of the INTT was completed. The detector was in stalled in the sPHENIX in March 2023. The
commissioning of the detector started. sPHENIX will start taking data in June 2023.

Members
Director
Yasuyuki AKIBA
Senior Research Scientists
Yuji GOTO
Itaru NAKAGAWA

Ralf SEIDL
Satoshi YOKKAICHISpecial Postdoctoral Researcher
Minho KIM
Special Temporary Research Scientist
Yasushi WATANABE
Visiting Scientists
Tatsuya CHUJO (Tsukuba Univ.)
Takashi HACHIYA (Nara Women’s Univ.)
Shoichi HASEGAWA (JAEA)
Motoi INABA (Tsukuba Univ. of Tech.)Shunzo KUMANO (Japan Women’s Univ.)
Ken-ichi NAKANO (Univ. of Virginia USA)

Masahiro OKAMURA (BNL)
Toshiaki SHIBATA (Nihon Univ.)
Kenta SHIGAKI (Hiroshima Univ.)
Maya SHIMOMURA (Nara Women’s Univ.)
Kiyoshi TANIDA (JAEA)

Student Trainees
Misaki HATA (Nara Women’s Univ.)
Yumika NAMIMOTO (Nara Women’s Univ.)
Yuka SASAKI (Nara Women’s Univ.)

Yuka SUGIYAMA (Nara Women’s Univ.)
Runa TAKAHAMA (Nara Women’s Univ.)
Mai WATANABE (Nara Women’s Univ.)

Interns
Kazuma FUJIKI (Rikkyo Univ.)
Tomoya KATO (Rikkyo Univ.)

Ryota SHISHIKURA (Rikkyo Univ.)

List of Publications & Presentations
Publications[Original Papers]
N. J. Abdulameer et al., “Improving constraints oon gluon
spin-momentum correlations in transversely polarized protons vias midrapidity√
open-heavy ﬂavor electrons in p + p collisions at s = 200 GeV,” Phys. Rev. D 107, 052012 (2023).
√
N. J. Abdulameer et al., “Low pT direct-photon production in Au + Au collisions at sNN = 39 and 62.4 GeV,” Phys. Rev. C 107, 024914(2023).
N. J. Abdulameer et al., “Measurement of second-harmonic Fourier coeﬃcients from azimuthal anisotropies in p + p, p + Au, d + Au,√
and 3 He + Au at sNN = 200 GeV,” Phys. Rev. C 107, 024907 (2023).
√√
N. J. Abdulameer et al., “Measurement of ϕ-meson production in Cu + Au at sNN = 200 GeV and U + U collisions at sNN = 193 GeV,”
Phys. Rev. C 107, 014907 (2022).
√
U. A. Acharya et al., “ϕ meson production in p + Al, p + Au, d + Au, 3 He + Au collisions at sNN = 200 GeV,” Phys. Rev. C 106,
014908 (2022).
U. A. Acharya et al., “Measurement of ψ(2S ) nuclear modiﬁcation at backward and forward rapidity in p+ p, p+ Al, and p+ Au collisions√
at sNN = 200 GeV,” Phys. Rev. C 105, 064912 (2022).
√
U. A. Acharya et al., “Systematic study of nuclear eﬀects in p + Al, p + Au, d + Au, and 3 He + Au collisions at sNN = 200 GeV using0
π production,” Phys. Rev. C 105, 064902 (2022).

Award
Y. Akiba, “Research of High temperature and high density matter through relativistic heavy ion collisions,” Commendation for Scienceand Technology by the Minister of Education, Culture, Sports, Science, and Technology for 2023.

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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
of Columbia University as its initial Director. 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, the former BNL director, N. P. Samios, who served until 2013. The other former BNL director, S. H. Aronson
led the Center from 2013. Hideto En’yo succeeded the director position starting from JFY 2017. Support for RBRC was initiallyfor ﬁve years and has been renewed four times, and presently extends to March 2023. The ﬁve year extension from April 2023 isagreed between BNL and RIKEN in order to cover the era of sPHENIX experiment which is the upgraded of the PHENIX experiment.
Theoretical activities in the RBRC Theory and Computing Groups 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 jointly works with RHIC Physics
Research Laboratory at Wako RIKEN, the RHIC Spin Group at BNL, the RHIC Spin Physics community, and the PHENIX/sPHENIX
collaboration. Radiation Laboratory at Wako was closed in March 2022, and its functions are taken over by the new laboratory “RHIC
Physics Research Laboratory” headed by Y. Akiba. BNL provides oﬃce space, management, computing, and administrative support.
The Deputy Director of RBRC is D. Morrison (BNL). In May 2021, Y. Hatta (BNL) becomes Theory Group leader, succeeding
D. Kharzeev. Y. Akiba (RIKEN) is Experimental Group leader and T. Izubuchi (BNL) is Computing Group leader. From April 2023,
Robert Tribble, the former deputy director for Science and Technology of BNL assumes the director of RBRC, after Hideto En’yo’s
retirement.

2. Major Research Subjects

Major research subjects of the theory group are(1) Spin structure of proton;(2) Gluon saturation at small-x;(3) Physics of quark gluon plasma.
Major research subjects of the computing group are(1) Search for new law of physics through tests for Standard Model of particle and nuclear physics;(2) Dynamics of QCD and related theories;(3) Theoretical and algorithmic development for lattice ﬁeld theories, QCD machine design.
Major research subject of the experimental group are(1) Experimental Studies of the Spin Structure of the Nucleon;(2) Study of Quark-Gluon Plasma at RHIC;(3) sPHENIX detector construction.

3. Summary of Research Activity

Summary of Research Activities of the three groups of the Center are given in the sections of each group.

Members
Director
Hideto EN’YO
Deputy Director
David P. MORRISON
Administrative Staﬀs
Keiko IWANO (Administration Manager)
Pamela ESPOSITO (Administrative Assistant)

Maureen MCNEIL-SHEA (Administrative Assistant)

List of Publications & Presentations
Publications[Original Papers]
See the lists of the research groups.

Presentations[Seminars]
H. En’yo, “My forty years of looking up to the world of Nambu (in Japanese),” Final lecture supported by the Chief Scientist Assemblyand Nishina Center of RIKEN, Wako, Saitama, Japan (RIKEN) & Online, March 2, 2023.

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H. En’yo, “My forty years of looking up to the world of Nambu (in English),” the special RBRC Seminar Celebrating the Retirement of
Dr. Hideto En’yo, the director of RIKEN BNL Research Center, Upton NY, USA (Brookhaven National Laboratory) & Online, March
23, 2023.

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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, inparticular, the physics explored by the RHIC experiment at Brookhaven National Laboratory (BNL). This includes: understandingof the Quark-Gluon Plasma (QGP); the nature of dense quark matter; the initial state in high energy collisions, the Color Glass
Condensate and its evolution to QGP through a Glasma; QCD spin physics; physics relevant to the future Electron-Ion Collider at
BNL.

2. Major Research Subjects(1) Heavy Ion Collisions, QCD phase diagram(2) Perturbative Quantum Chromo-Dynamics (QCD)(3) Nucleon structure, mass and spin

3. Summary of Research Activity(1) Chiral and trace anomalies in Deeply Virtual Compton Scattering
Y. Hatta, S. Bhattacharya and a collaborator discovered novel ‘anomaly poles’ in QCD Compton scattering. These are poles 1/t
in momentum transfer t in oﬀ-forward scattering and are manifestations of the underlying QCD chiral and trace anomalies. This has
signiﬁcant implications for the future tomographic study of the nucleon through the generalized parton distributions (GPDs).
(2) Gravitational form factors in holographic QCD
Y. Hatta and collaborators computed one of the gravitational form factors, the so-called D-term, in holographic QCD using the
Sakai-Sugimoto model. This is the ﬁrst computation of the gravitational form factors in top-down holographic QCD. They foundthat the D-term exhibits the phenomenon of glueball dominance, similar to the vector meson dominance of the electromagnetic form
factors.
(3) Small-x behavior of the GPD Eg(x)Y. Hatta and a collaborator derived, for the ﬁrst time, the small-x evolution equation for the gluon GPD Eg(x). It has been shown
that, despite its association with nucleon helicity-ﬂip processes, Eg(x) grows rapidly with decreasing x in exactly the same way as the
BFKL Pomeron.
(4) Lee-Yang edge singularity
V. Skokov and collaborators employ the functional renormalization group approach at next-to-leading order of the derivative
expansion to reﬁne their earlier ﬁndings for the universal location of the Yang-Lee edge singularity in classic O(N) universality
classes. To this date, it is the most precise determination of the Yang-Lee edge singularity.
(5) CGC for ultraperipheral nuclear collisions
V. Skokov and collaborators provided the ﬁrst calculation of two-gluon production at mid-rapidity in ultra-peripheral collisions in
the Color Glass Condensate framework. To estimate systematic uncertainty associated with poor understanding of the wave functionof the nearly real photon, they consider two diametrically diﬀerent models: the dilute quark-antiquark dipole approximation and avector meson, in which color charge density is approximated by McLerran-Venugopalan model.
(6) Simulating the tiniest ﬂuids in 3 + 1 dimensions
Employing a dynamical initial state model coupled to (3 + 1)D viscous relativistic hydrodynamics, C. Shen and collaborators
explored the rapidity dependence of anisotropic ﬂow in the Relativistic Heavy-Ion Collider (RHIC) small system scan at 200 GeV
center of mass energy [6]. They demonstrate that approximately 50% of the pT -diﬀerential triangular ﬂow diﬀerence between themeasurements by the STAR and PHENIX Collaborations can be explained by the use of reference ﬂow vectors from diﬀerent rapidity
regions. This emphasizes the importance of longitudinal ﬂow decorrelation for anisotropic ﬂow measurements in asymmetric nuclear
collisions and the need for (3 + 1)D simulations.
(7) Multi-scale imaging of nuclei geometry at high energy
C. Shen and collaborators showed that the failure to describe the v2 ratio in central UU and AuAu collisions at RHIC was due toinappropriate treatments of well-deformed nuclei in modeling the initial conditions of the QGP [8]. With rigorous input from Skyrme
density functional calculations, they show that correcting nuclear deformations in hydrodynamic simulations restores agreement with
BNL RHIC data. This brings consistency to the results of nuclear experiments across energy scales and demonstrates the impact of
the hexadecapole deformation of Uranium nucleus on high-energy collisions.

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RIKEN Accel. Prog. Rep. 56 (2023)(8) Renormalization of jet quenching parameter
Y. Mehtar-Tani and collaborators demonstrated that the leading quantum corrections to parton energy loss can be resummed andincorporated through a renormalization of the jet quenching parameter, while still preserving the classical tree-level framework. The
renormalized jet quenching now depends on the length of the medium, owing to non-local quantum eﬀects, resulting in a weakly
non-Markovian dynamics. Based on this theory result, they developed a systematic approach with signiﬁcant implications for jet
quenching phenomenology.

Members
Group Leader
Yoshitaka HATTARBRC Researchers
Yacine MEHTAR-TANI
Chun SHEN

Vladimir SKOKOV
Bhattacharya SHOHINI

List of Publications & Presentations
Publications[Original Papers]
Y. Hatta, B. Xiao, and F. Yuan, “Semi-inclusive diﬀractive deep inelastic scattering at small-x,” Phys. Rev. D 106, 094015 (2022).
M. Fujita, Y. Hatta, S. Sugimoto, and T. Ueda, “Nucleon D-term in holographic quantum chromodynamics,” Prog. Theor. Exp. Phys,
2022, 093B06 (2022).
Y. Hatta and J. Zhou, “Small-x evolution of the gluon GPD Eg,” Phys. Rev. Lett. 129, 25 (2022).
S. Bhattacharya, Y. Hatta, and W. Vogelsang, “Chiral and trace anomalies in deeply virtual Compton scattering,” Phys. Rev. D 107, 014026(2023).
A. Kumar et al. [JETSCAPE], “Inclusive jet and hadron suppression in a multistage approach,” Phys. Rev. C 107, 034911 (2023).
K. J. Sun, R. Wang, C. M. Ko, Y. G. Ma, and C. Shen, “Unveiling the dynamics of nucleosynthesis in relativistic heavy-ion collisions,”
arXiv:2207.12532.
W. Fan et al. [JETSCAPE], “Multiscale evolution of charmed particles in a nuclear medium,” Phys. Rev. C 107, 054901 (2023).
H. Alalawi, J. Boyd, C. Shen, and M. Strickland, “Impact of ﬂuctuating initial conditions on bottomonium suppression in 5.02 TeV
heavy-ion collisions,” Phys. Rev. C 107, L031901 (2023).
L. Du, C. Shen, S. Jeon, and C. Gale, “Probing initial baryon stopping and equation of state with rapidity-dependent directed ﬂow ofidentiﬁed particles,” arXiv:2211.16408.
W. Zhao, S. Ryu, C. Shen, and B. Schenke, “3D structure of anisotropic ﬂow in small collision systems at energies available at the BNL
Relativistic Heavy Ion Collider,” Phys. Rev. C 107, 014904 (2023).
Y. Tachibana et al. [JETSCAPE], “Hard jet substructure in a multi-stage approach,” arXiv:2301.02485.
W. Ryssens, G. Giacalone, B. Schenke, and C. Shen, “Evidence of hexadecapole deformation in uranium-238 at the relativistic heavy ion
collider,” accepted by Phys. Rev. Lett, arXiv:2302.13617.
H. Mäntysaari, B. Schenke, C. Shen, and W. Zhao, “Multi-scale imaging of nuclear deformation at the electron ion collider,”arXiv:2303.04866.
T. Schaefer and V. Skokov, “Dynamics of non-Gaussian ﬂuctuations in model A,” Phys. Rev. D 106, 014006 (2022).
H. Duan, A. Kovner, and V. V. Skokov, “CGC for ultra-peripheral Pb + Pb collisions at the Large Hadron Collider: a more realistic
calculation,” J. High Energy Phys. 12, 077 (2022).
G. Johnson, F. Rennecke, and V. V. Skokov, “Universal location of Yang-Lee edge singularity in classic O(N) universality classes,”arXiv:2211.00710.
H. Duan, A. Kovner, and V. V. Skokov, “Classical entanglement and entropy,” arXiv:2301.05735.
P. Caucal and Y. Mehtar-Tani, “Universality aspects of quantum corrections to transverse momentum broadening in QCD media,” J. HighEnergy Phys. 09, 023 (2022).
P. Caucal and Y. Mehtar-Tani, “Transverse momentum broadening from NLL BFKL to all orders in pQCD,” arXiv:2209.08900.
Y. Mehtar-Tani, S. Schlichting, and I. Soudi, “Jet thermalization in QCD kinetic theory,” arXiv:2209.10569.

[Proceedings]
Y. Hatta, “Nucleon EDM from polarized DIS,” JPS Conf. Proc. 37, 020601 (2022).
S. Benic, Y. Hatta, A. Kaushik, and H. Li, “A novel contribution to single spin asymmetries in SIDIS at two loops,” JPS Conf. Proc. 37,
020203 (2022).
S. Bhattacharya, K. Cichy, M. Constantinou, J. Dodson, X. Gao, A. Metz, S. Mukherjee, A. Scapellato, F. Steﬀens, and Y. Zhao, “GPDsin asymmetric frames,” PoS Lattice 2022, 095 (2023).
H. Mäntysaari, B. Schenke, C. Shen, and W. Zhao, “Bayesian inference of the ﬂuctuating proton shape in DIS and hadronic collisions,”
Acta Phys. Polon. Supp. 16, 33 (2023).

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V. Vovchenko, V. Koch, and C. Shen, “Proton number cumulants and correlation functions from hydrodynamics and the QCD phase
diagram,” Acta Phys. Polon. Supp. 16, 83 (2023).
C. Shen, W. Zhao, and B. Schenke, “Collectivity in ultra-peripheral heavy-ion collisions,” EPJ Web Conf. 276, 01002 (2023).
Y. Tachibana, C. Shen et al. [JETSCAPE], “Comprehensive study of multi-scale jet-medium interaction,” arXiv:2212.12188.

Presentations[International Conferences/Workshops]
Y. Hatta (invited), “EIC science: ep reactions,” Town hall meeting on hot & cold QCD, USA (MIT), September 20–22, 2022.
Y. Hatta (invited), “Nucleon D-term in the Sakai-Sugimoto model,” INT Workshop on Origin of the Visible Universe: Unraveling theProton Mass, USA (University of Washington), June 13–17, 2022.
Y. Hatta (invited), “Experimental observables to access GTMDs,” Towards improved hadron femtography with hard exclusive reactions,
USA (Virginia Tech University), July 18–22, 2022.
Y. Hatta (invited), “Nucleon EDM and polarized DIS,” QCD evolution, University of Virginia, May 9–13, 2022.
Y. Hatta (invited), “Azimuthal angular correlation of jets from soft gluon radiation,” RBRC workshop on predictions for sPHENIX, USA(BNL), July 20–22, 2022.
S. Bhattacharya (invited), “Hunting for gluon orbital angular momentum at the EIC,” XXIX Cracow Epiphany Conference on Physics atthe EIC and Future Facilities, Cracow, Poland, January 18, 2023.
S. Bhattacharya (invited), “Chiral and trace anomalies in DVCS,” CFNS Meetings, USA (Stony Brook University), March 10, 2023.
C. Shen (selected contributed talk), “Collectivity and baryon junctions in ultra-peripheral heavy-ion collisions,” the 20th International
Conference on Strangeness in Quark Matter, June 14, 2022.
C. Shen (invited), “Going beyond ﬂow: Did we hit the precision wall?,” First CMS Heavy-Ion Workshop, August 8, 2022.
C. Shen (invited), “Multi-messenger heavy-ion physics with JETSCAPE,” 13th International workshop on Multiple Partonic Interactionsat LHC, November 15, 2022.
C. Shen (invited), “3D modeling of the RHIC isobar collisions,” Intersection of Nuclear Structure and High-energy Nuclear Collisions,February 17, 2023.
C. Shen (invited), “Illuminating early-stage dynamics of heavy-ion collisions through photons at RHIC BES energies,” 11th International
Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collision, March 29, 2023.
Y. Mehtar-Tani (invited), “Quantum induced anomalous diﬀusion in QCD matter,” Jet Quenching In The Quark-Gluon Plasma workshop,
ECT*, Trento, June 13–17, 2022.
Y. Mehtar-Tani (invited), “Transverse momentum broadening from NLL BFKL to all orders in pQCD,” Resummation Evolution Factorization, October 31–November 4, 2022.
Y. Mehtar-Tani (invited), “Jet energy loss and heavy ﬂavor, Heavy Flavors from small to large systems,” Institut Pascal Program, Orsay,
France (Paris-Saclay University), October 3–21, 2022.
Y. Mehtar-Tani (invited), “Transverse momentum broadening from NLL BFKL to all orders in pQCD,” 13th international workshop on
Multiple Partonic Interactions at the LHC, Madrid, Spain, November 14–18, 2022.

[Domestic Conference/Workshop]
Y. Hatta (invited), “Nucleon graivitational form factors in holographic QCD,” Third International Workshop on the Extension Project for
the J-PARC, Hadron experimental facility, Japan (J-PARC), March 14–16, 2023.

[Seminars]
Y. Hatta, “QCD spin physics at the EIC,” Heavy-ion tea seminar, USA (Lawrence Berkeley National Laboratory), October 14, 2022.
Y. Hatta, “Chiral and trace anomalies in DVCS,” Stony Brook, USA, November 2, 2022.
Y. Hatta, “Azimuthal angular asymmetry of soft gluons in jet production, USA (Yale University), April 28, 2022.
Y. Hatta, “Near-threshold quarkonium production and the nucleon gravitational form factors,” CFNS seminar, USA (Stony Brook University), August 25, 2022.
S. Bhattacharya, “Primary observables to access orbital angular momentum of partons,” Nuclear Physics Seminar, USA (University of
Illinois Urbana-Champaign), February 13, 2023.
S. Bhattacharya, “Computing PDFs and GPDs in Lattice QCD: Recent Progress,” Center for Nuclear Theory seminar, USA (Stony Brook
University), February 22, 2023.
C. Shen, “Longitudinal dynamics and particle production in relativistic nuclear collisions,” RBRC seminar, July 7, 2022.
C. Shen, “Flowing through the nuclear phase diagram at the highest temperatures and densities,” Physics colloquium at Wayne State
University, October 6, 2022.
C. Shen, “3D modeling of the collective behaviors in relativistic heavy-ion collision,” Nuclear Seminar at HENPIC-EVO, December 22,
2022.
C. Shen, “3D modeling of the collective behaviors in relativistic heavy-ion collisions,” Nuclear Seminar at Iowa State University, February
23, 2023.
Y. Mehtar-Tani, “The hottest matter under the microscope: probing the quark gluon plasma at colliders,” BNL lecture, Upton (BNL),
December 14, 2022.
Y. Mehtar-Tani, “Quantum induced anomalous diﬀusion in QCD matter,” Teilchentee seminar at ITP, Heidelberg, Germanuy (Heidelberg- 359 -

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University), June 2, 2022.
Y. Mehtar-Tani, “3D-structure of the proton: from partons to strong ﬁelds,” UCLA Nuclear Physics Group, Los Angeles, CA (UCLA),
September 15, 2022.

Press Release
S. Bhattacharya, R. Boussarie, and Y. Hatta, “Theorists propose a novel way to measure gluons’ orbital motion,” DOE highlights, November 10, 2022.

Awards
C. Shen, 2023 Outstanding Junior Faculty Award, Wayne State Academy of Scholars, https://academy.wayne.edu/junior-award .
V. Skokov, LeRoy and Elva Martin Award for Teaching Excellence (NCSU).

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Subnuclear System Research Division
RIKEN BNL Research Center
Experimental Group
1. Abstract

RIKEN BNL Research Center (RBRC) Experimental Group studies the strong interactions (QCD) using RHIC accelerator at
Brookhaven National Laboratory, the world ﬁrst heavy ion collider and polarized p + p collider. We have three major activities: Spin
Physics at RHIC, Heavy ion physics at RHIC, and detector upgrades of PHENIX experiment at RHIC.
We study the spin structure of the proton using the polarized proton-proton collisions at RHIC. This program has been promoted
by RIKEN’s leadership. The ﬁrst focus of the research is to measure the gluon spin contribution to the proton spin. Results fromPHENIX π0 measurement and STAR jet measurement has shown that gluons in the proton carry about 30% of the proton spin. This isa major milestone of the RHIC spin program. The second goal of the spin program is to measure the polarization of anti-quarks in the
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 focus of the RHIC spin program is moved to study of transverse spin measurement.
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 QGP. We measured direct photons in Au + Au
collisions for 1 < pT < 3 GeV/c, where thermal radiation from hot QGP is expected to dominate. The comparison between the data
and theory calculations indicates that the initial temperature of 300 MeV to 600 MeV is achieved. These values are well above thetransition 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. 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 of charm decay electron for
3 < pT < 4 GeV/c. PHENIX recorded 10 times as much Au + Au collisions data in each of the 2014 run and 2016 run. A paper on the
suppression of electrons from charm and bottom decays in the 2014 run was submitted for publication. The data shows clear diﬀerentof the suppression of b → e and c → e.
PHENIX completed its data taking in 2016, and construction of a new detector, sPHENIX, as upgrade of PHENIX was started.
sPHENIX will measure jets, photons, and Upsilon particles and will complete the scientiﬁc mission of RHIC. We constructed aintermediate-silicon tracker INTT for sPHENIX. INTT was completed in 2022 and it was installed in sPHENIX in March 2023. The
sPHENIX will start taking data in 2023.

2. Major Research Subjects(1) Experimental Studies of the Spin Structure of the Nucleon(2) Study of Quark-Gluon Plasma at RHIC
(3) sPHENIX INTT detector

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. Y. Akiba (Experimental Group Leader) is the Spokesperson of PHENIX experiment since 2016.
(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 gluon spin. PHENIX measured the parity-violating single spin
asymmetry AL of the W boson production in p + p in wide rapidity range. The results of the W boson measurements were publishedin 2016 and 2018, and these results give constraints on the anti-quark polarization in the proton. The focus of the spin physics is now
moved to the measurements of the single transverse spin asymmetry AN .
PHENIX measured AN of single electrons from heavy ﬂavored hadrons at mid rapidity. Production of heavy quarks (charm andbottom) is dominated by gluon-gluon fusion, and the measurement is sensitive to the gluon correlators that are related to the orbital
angular momentum of gluons via theoretical models. Figure 1 shows the AN of single electrons from heavy ﬂavor decays. The data

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Fig. 1. The single spin asymmetry AN of heavy ﬂavor decay electrons (left) and the constraint on the model parameter from the data (right). Published in Phys.
Rev. D 107, 052012 (2023).

are compared with a theoretical model by Z. Kang and J. Qiu, and the two parameters λ f and λd of the model are constrained from thedata. The right panel of Fig. 1 shows the constraint on the model parameters. The parameters are determined as λ f = −0.01±0.03 GeV
and λd = 0.11 ± 0.09 GeV. The size of these parameters are expected to be O(0.1)GeV. This is the ﬁrst constraints on these model
parameters. These results are published in Physical Review D.
(2) Experimental study of Quark-Gluon Plasma using RHIC heavy-ion collider
The goal of high energy heavy ion physics at RHIC is study of QCD in extreme conditions i.e. at very high temperature and atvery high energy density. Experimental results from RHIC have established that dense partonic matter is formed in Au + Au collisions
at RHIC. The matter is very dense and opaque, and it has almost no viscosity and behaves like a perfect ﬂuid. These conclusions areprimarily based on the following two discoveries:• Strong suppression of high transverse momentum hadrons in central Au + Au collisions (jet quenching);• Strong elliptic ﬂow.
These results are summarized in PHENIX White paper, which has more than 3400 citations to date. The focus of the research inheavy ion physics at RHIC is now to investigate the properties of the matter. RBRC have played the leading roles in some of the mostimportant results from PHENIX in the study of the matter properties. These include (1) measurements of heavy quark production fromthe single electrons from heavy ﬂavor decay (2) measurements of J/ψ production (3) measurements of 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 predicted that
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 canreproduce the central Au + A data within a factor of two. These models assume formation of a hot system with initial temperature of
T init = 300 MeV to 600 MeV. This is the ﬁrst measurement of initial temperature of quark gluon plasma formed at RHIC. Y. Akiba
received 2011 Nishina memorial Prize mainly based on this work.
PHENIX experiment recently measured the ﬂow in small collision systems (p + Au, d + Au, and 3 He + Au), and observed strong
ﬂow in all of these systems. Theoretical models that assume formation of small QGP droplets best describe the data. These results are
published in Nature Physics in 2019.
We constructed VTX detector of PHENIX. VTX is a 4-layer silicon tracker and it is the main device for measurement of charmand bottom quark production in PHENIX. VTX took data from the 2011 to 2016 when PHENIX completed data taking. PHENIX
recorded high statistics Au + Au data, approximately 20 billion events with VTX in each of the 2014 run and the 2016 run. A paper
reporting the results of 2014 run was submitted to Physical Review C.
PHENIX measured the nuclear modiﬁcation factor of J/ψ and ψ(2S ) in the forward and the backward direction in p + Au and√d + Au collisions at sNN = 200 GeV. The results are shown in Fig. 2.
In the forward rapidity region, the suppression of J/ψ and ψ(2S ) is similar. This indicates that initial state eﬀects such as
shadowing dominates in this region. In the backward rapidity region, the stronger suppression of ψ(2S ) than J/ψ is observed. This
result suggests presence of ﬁnal state eﬀect in p + Au collisions. The paper reporting these results was published in Physical Review
C and it was selected as Editor’s suggestion.
√
PHENIX measured low pT direct photons in Au + Au collisions at sNN = 39 and 62 GeV. The yield of these photons exceeds
what is expected from p + p collisions at the same energy and it is consistent with large contribution from thermal photons from a
hot quark-gluon plasma. Compared with the data of other collision energies, the data suggest that the bulk of thermal photons are- 362 -

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Fig. 2. The nuclear modiﬁcation factor of J/ψ and ψ(2S ) in small collision systems as function of rapidity. Published in Phys. Rev. C 105, 064912 (2022).

Fig. 3. Eﬀective temperature, T eﬀ , from the low pT direct photon spectra as function of the collision energy. Published in Phys. Rev. C 107, 024914 (2023).

emitted near the transition of the quark-gluon plasma. The paper reporting these results was published in Physical Review C, and it
was selected as Editor’s suggestion.
(3) sPHENIX INTT detector
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. 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 and bottom) 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 ﬁrst observation that bottom suppression is smaller
than charm. We have recorded 10 times as much Au + Au collisions data in each of the 2014 run and 2016 run. The results ofbottom/charm ratios in p + p collisions at 200 GeV from the 2015 run was published (Phys. Rev. D 99, 092003 (2019)). A paper
reporting measurements of the nuclear suppression factor RAA of charm and bottom in Au + Au collisions from the 2014 data wassubmitted for publication to Physical Review C.
PHENIX completed its data taking in 2016. We constructed intermediate silicon tracker INTT for sPHENIX, a new experiment at
RHIC that will start taking data in 2023. INTT was completed in fall 2022 and it was installed in sPHENIX in March 2023. sPHENIX
will start taking data in June 2023.

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Fig. 4. Left: Completed two halves of INTT detector with members of INTT teams. Right: INTT detector and INTT team just after installation to sPHENIX.

Members
Group Leader
Yasuyuki AKIBARBRC Researchers
Jan C. BERNAUER
Genki NUKAZUKA
Yuji GOTO

Itaru NAKAGAWA
Ralf SEIDL
Atsushi TAKETANISpecial Postdoctoral Researcher
Minho KIM
Junior Research Associate
Takuya KUMAOKA
Special Temporary Research Scientists
Takashi ICHIHARA

Yasushi WATANABE

Senior Visiting Scientist
Rachid NOUICER (BNL)
Visiting Scientists
Stefan BATHE (City Univ. of New York)Takashi HACHIYA (Nara Women’s Univ.)
Gaku MITSUKA (KEK)

Takao SAKAGUCHI (BNL)
Takashi SAKO (Univ. of Tokyo)
Milan STOJANOVIC (Purdue Univ.)

Visiting Researcher
Shima SHIMIZU (JSPS)
Student Trainees
Joseph T. BERTAUX (Purdue Univ.)
Kai-Yu CHENG (Nat’l Central Univ.)
Jaein HWANG (Korea Univ.)
Seunghwan LEE (Sejong Univ.)

Han-Sheng LI (Purdue Univ.)
Cheng Wei SHIH (Nat’l Central Univ.)
Wei-Che TANG (Nat’l Central Univ.)
Maki WAKATA (Rikkyo Univ.)

Research Part-time Worker
Hikaru IMAI

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List of Publications
Publications[Original Papers]
N. J. Abdulameer et al., “Improving constraints oon gluon
spin-momentum correlations in transversely polarized protons vias midrapidity√
open-heavy ﬂavor electrons in p + p collisions at s = 200 GeV,” Phys. Rev. D 107, 052012 (2023).
√
N. J. Abdulameer et al., “Low pT direct-photon production in Au + Au collisions at sNN = 39 and 62.4 GeV,” Phys. Rev. C 107, 024914(2023).
N. J. Abdulameer et al., “Measurement of second-harmonic Fourier coeﬃcients from azimuthal anisotropies in p + p, p + Au, d + Au,√
and 3 He + Au at sNN = 200 GeV,” Phys. Rev. C 107, 024907 (2023).
√√
N. J. Abdulameer et al., “Measurement of ψ-meson production in Cu + Au at sNN = 200 GeV and U + U collisions at sNN = 193 GeV,”
Phys. Rev. C 107, 014907 (2022).
√
U. A. Acharya et al., “ψ meson production in p + Al, p + Au, d + Au, 3 He + Au collisions at sNN = 200 GeV,” Phys. Rev. C 106, 014908(2022).
U. A. Acharya et al., “Measurement of ψ(2S ) nuclear modiﬁcation at backward and forward rapidity in p+ p, p+ Al, and p +Au collisions√
at sNN = 200 GeV,” Phys. Rev. C 105, 064912 (2022).
√
U. A. Acharya et al., “Systematic study of nuclear eﬀects in p + Al, p + Au, d + Au, and 3 He + Au collisions at sNN = 200 GeV using
π0 production,” Phys. Rev. C 105, 064902 (2022).

Award
Y. Akiba, “Research of High temperature and high density matter through relativistic heavy ion collisions,” Commendation for Scienceand Technology by the Minister of Education, Culture, Sports, Science, and Technology for 2023.

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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 forhigh energy particle and nuclearphysics. 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 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. The ﬁrst-principle studies also elucid intrecate nature of various phenomena in quantitive and unambiguous
manners. 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 computing codes, developments for computing algorithms,
and researches of particle, nuclear, and lattice theories. Since the inception of RBRC, many breakthroughs and pioneering works
has carried out in computational forefronts. These are the use of the domain-wall fermions, which preserve chiral symmetry, a key
symmetry for understanding dynamics of subnuclear elementary particle quark, the three generations of QCD devoted supercomputersand very eﬃcient software library for lattice gauge theories, pioneering works for QCD calculation for Cabibbo-Kobayashi-Maskawa
theory, QCD + QED simulation for isospin breaking, novel algorithms for statistical error reduction in general lattice calculation etc.
The chiral quark simulation has been performed in a uncompromised setup at the physical up, down quark mass, the precision formany basic quantities reached to accuracy of sub-percent, and the group is working 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.
Recent focus area is stusies of the nucleon’s shape, structures, and the motion of quarks and gluon inside nucleon called parton
distribution, which provide theoretical guidance to physics for sPHENIX and future Electron Ion Collider (EIC), Hyper Kamiokande,
DUNE. Closely related calculation has been carried out for the origin of the current matter rich universe (rather than anti-matter).
Towards ﬁnite density QCD, they also explored Quantum Computing for ﬁeld theories. Applications of the Machine Learning (ML)and Artiﬁcial Intelligence (AI) for novel and more eﬃcient ways to carry out lattice QCD calculations are among the new topics ofthe group.

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 sPHENIX, Electron Ion Collider (EIC or eRHIC), Hyper Kamiokande, T2K, DUNE, or the matter rich universe(3) Theoretical and algorithmic development for lattice ﬁeld theories, QCD machine (co-)design and software development

3. Summary of Research Activity

Research activities during the current report period by RBRC members include various nulcleon formfactor and structure calculations, hadronic contributions to the anomalous magnetic moment (g − 2)µ , kaon and B meson physics, and algorithm & softwaredevelopments.
In April 2020, (g − 2)µ experiment collaboration at FNAL carried out a very precise measurement of precession rate of muons
under magnetic ﬁeld to 0.14 parts per million accuracy. This provides a very stringent test of the current understanding of elementary
particle physics so called the Standard Model of particle physics. The strong interaction of quark and gluon is described by Quantum
Chromo Dyanics (QCD) and is a dominant source of uncertainty in the theoretical prediction of (g − 2)µ . Members of RBRC has
been working on the two separate mode of QCD contributions, Hadronic Vacuum Polarization (HVP) and Hadronic Light-by-Light(HLbL). This year, an update of HVP was reported with an improved precision by adding calculation on the ﬁnner space-time lattice
to remove systematic error due to non-zero lattice spacing. The quantities are not yet the ﬁnal total conribution for (g − 2)µ but a largepart of QCD contributionfrom intermediate energies scale, roughly 200 MeV–1 GeV. The new results of HVP contribution turned out
signiﬁcantly larger than our previous results and consistent with other lattice QCD calcuation by other groups, which emphasis theimportance and diﬃculty of removing lattice spacing error. No an interesting observation is our new value (and other lattice QCD
values) has about 4+σ tention to the HVP prediction from hadronic cross section in electron-position collision. It is important to note
this is still a comparison of the partial HVP contribution from the intemediate energy region, and the ﬁnal total HVP contribution
including other energies as well as the other systematic eﬀects is ongoing to updated with greater precision soon.
This is only a selected research highlight of members of RBRC this year among other various researches: Machine Learning- 366 -

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q = p′ − p, νpp′

RBC/UKQCD 2018
ETMC 2021
BMW 2020
Mainz 2022
ETMC 2022
RBC/UKQCD 2023
RBC/UKQCD 2018/FJ
Aubin et al. 2019/CL/KNT
BMW 2020/KNT
Colangelo et al. 2022
224 226 228 230 232 234 236 238 240Waµ (0.4 fm, 1.0 fm, 0.15 fm) × 10

10

Hadron Models
Dispersive + Data
Lattice
PdRV 09

q = p′ − p, ν

N/JN 09
FJ 17
White paper 20pp′

RBC-UKQCD 19
Mainz 21
This Work

Fig. 1. Feynman diagrams for Lattice QCD computations of Muon’s anomalous magnetic moment (g − 2)µ . Hadronic Vaccum Polarization contribution (Left) and Hadronic Light-by-Light contribution (Right).

4

6

8

10

12

14

16

18

aHLbL
× 1010µFig. 2. Current summary of the Hadronic Light-by-Light contribution(HLbL) contribution for Muon’s anomalous magnetic moment (g − 2)µ .
Above the upper horizontal line shows various Lattice QCD determinations of HVP while the red results from hadronic decay of electron
positron scattering (R-ratio), the green bands is the experimental resultsof (g − 2)µ showing a 3–4σ discrepancies.

for Lattice QCD ensemble generation, Lattice QCD sampling for non-zero baryon density and sign problem, real-time lattice QCD
formulation in Minkowski space-time, solving critical slowing down problem via trivializing maps, lattice QCD+QED and isospin
breaking of hadrons and their decays, HLbL for (g−2)µ , nucleon electric dipole moment and matter-rich universe, nucleon anti-nucleon
oscillation, proton decay, CP violating K → ππ decay and ε′ /ε, etc.
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.

Members
Group Leader
Taku IZUBUCHI
RBRC Researchers
Luchang JIN

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Special Postdoctoral Researcher
Nobuyuki MATSUMOTO
Visiting Scientists
Thomas BLUM (Univ. of Connecticut)
Hiroshi OKI (Nara Women’s Univ.)

Akio TOMIYA (In’l Professional Univ. of Technology in Osaka)

List of Publications & Presentations
Publications[Original Papers]
T. Blum, P. A. Boyle, M. Bruno, D. Giusti, V. Gülpers, R. C. Hill, T. Izubuchi, Y. C. Jang, L. Jin, and C. Jung et al., arXiv:2301.08696.
T. Blum et al. [RBC and UKQCD], “Isospin 0 and 2 two-pion scattering at physical pion mass using all-to-all propagators with periodic
boundary conditions in lattice QCD,” Phys. Rev. D 107, 094512 (2023).
J. S. Yoo, Y. Aoki, P. Boyle, T. Izubuchi, A. Soni, and S. Syritsyn, “Proton decay matrix elements on the lattice at physical pion mass,”
Phys. Rev. D 105, 074501 (2022).
G. Rendon, T. Izubuchi and Y. Kikuchi, “Eﬀects of cosine tapering window on quantum phase estimation,” Phys. Rev. D 106, 034503(2022).
B. Chakraborty, M. Honda, T. Izubuchi, Y. Kikuchi, and A. Tomiya, “Classically emulated digital quantum simulation of the Schwinger
model with a topological term via adiabatic state preparation,” Phys. Rev. D 105, 094503 (2022).
X. Gao, A. D. Hanlon, J. Holligan, N. Karthik, S. Mukherjee, P. Petreczky, S. Syritsyn, and Y. Zhao, “The Unpolarized Proton PDF at
NNLO from Lattice QCD with Physical Quark Masses,” arXiv:2212.12569.
X. Gao, A. D. Hanlon, N. Karthik, S. Mukherjee, P. Petreczky, P. Scior, S. Shi, S. Syritsyn, Y. Zhao, and K. Zhou, “Continuum-extrapolated
NNLO valence PDF of the pion at the physical point,” Phys. Rev. D 106, 114510 (2022).
X. Gao, A. D. Hanlon, N. Karthik, S. Mukherjee, P. Petreczky, P. Scior, S. Syritsyn, and Y. Zhao, “Pion distribution amplitude at thephysical point using the leading-twist expansion of the quasi-distribution-amplitude matrix element,” Phys. Rev. D 106, 074505 (2022).
X. Gao, A. D. Hanlon, S. Mukherjee, P. Petreczky, P. Scior, S. Syritsyn, and Y. Zhao, “Lattice QCD determination of the Bjorken-x
dependence of parton distribution functions at next-to-next-to-leading order,” Phys. Rev. Lett. 128, 142003 (2022).
X. Gao, N. Karthik, S. Mukherjee, P. Petreczky, S. Syritsyn, and Y. Zhao, “Pion form factor and charge radius from Lattice QCD at
physical point,” Phys. Rev. D 104, 11 (2021).
X. Gao, N. Karthik, S. Mukherjee, P. Petreczky, S. Syritsyn, and Y. Zhao, “Towards studying the structural diﬀerences between the pionand its radial excitation,” Phys. Rev. D 103, 094510 (2021).
G. Silvi, S. Paul, C. Alexandrou, S. Krieg, L. Leskovec et al., “P-wave nucleon-pion scattering amplitude in the Delta(1232) channel fromlattice QCD,” Phys. Rev. D 103, 094508 (2021).
M. Yu. Barabanov, M. A. Bedolla, W. K. Brooks, G. D. Cates, C. Chen et al., “Diquark correlations in hadron physics: Origin, impact
and evidence,” Prog. Part. Nucl. Phys. 116, 103835 (2021).
Y. Hamada and N. Matsumoto, “Energy of the boundary of spacetime,” Prog. Theor. Exp. Phys. 2023, 033B02 (2023).
N. Matsumoto, “Comment on the subtlety of deﬁning a real-time path integral in lattice gauge theories,” Prog. Theor. Exp. Phys. 2022,
093B03 (2022).
X. Y. Tuo, X. Feng, and L. C. Jin, “Lattice QCD calculation of the light sterile neutrino contribution in 0ν2β decay,” Phys. Rev. D 106,
074510 (2022).
Y. Fu, X. Feng, L. C. Jin, and C. F. Lu, “Lattice QCD calculation of the two-photon exchange contribution to the muonic-hydrogen lambshift,” Phys. Rev. Lett. 128, 172002 (2022).
X. Feng, L. Jin, and M. J. Riberdy, “Lattice QCD calculation of the pion mass splitting,” Phys. Rev. Lett. 128, 052003 (2022).
X. Y. Tuo, X. Feng, L. C. Jin, and T. Wang, “Lattice QCD calculation of K → ℓνℓℓ′ + ℓ′ -decay width,” Phys. Rev. D 105, 054518 (2022).
P. X. Ma, X. Feng, M. Gorchtein, L. C. Jin, and C. Y. Seng, “Lattice QCD calculation of the electroweak box diagrams for the kaon
semileptonic decays,” Phys. Rev. D 103, 114503 (2021).

[Review Articles]
N. Craig, C. Csáki, A. X. El-Khadra, Z. Bern, R. Boughezal, S. Catterall, Z. Davoudi, A. de Gouvêa, P. Draper, and P. J. Fox et al.,“Snowmass Theory Frontier Report,” arXiv:2211.05772.
Z. Davoudi, E. T. Neil, C. W. Bauer, T. Bhattacharya, T. Blum, P. Boyle, R. C. Brower, S. Catterall, N. H. Christ, and V. Cirigliano et al.,“Report of the snowmass 2021 topical group on lattice gauge theory,” arXiv:2209.10758.
A. S. Kronfeld et al. [USQCD], “Lattice QCD and particle physics,” arXiv:2207.07641.
P. Boyle, D. Bollweg, R. Brower, N. Christ, C. DeTar, R. Edwards, S. Gottlieb, T. Izubuchi, B. Joo, and F. Joswig et al. “Lattice QCD andthe computational frontier,” arXiv:2204.00039.
G. Colangelo, M. Davier, A. X. El-Khadra, M. Hoferichter, C. Lehner, L. Lellouch, T. Mibe, B. L. Roberts, T. Teubner, and H. Wittig etal. “Prospects for precise predictions of aµ in the standard model,” arXiv:2203.15810.
T. Blum, P. Boyle, M. Bruno, N. Christ, F. Erben, X. Feng, V. Guelpers, R. Hill, R. Hodgson, and D. Hoying et al., “Discovering new
physics in rare kaon decays,” arXiv:2203.10998.

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R. Alarcon, J. Alexander, V. Anastassopoulos, T. Aoki, R. Baartman, S. Baeßler, L. Bartoszek, D. H. Beck, F. Bedeschi, and R. Berger etal. “Electric dipole moments and the search for new physics,” arXiv:2203.08103.
D. Bollweg, D. A. Clarke, J. Goswami, O. Kaczmarek, F. Karsch, S. Mukherjee, P. Petreczky, C. Schmidt, and S. Sharma, ‘Equation of state and speed of sound of (2+1)-ﬂavor QCD in strangeness-neutral matter at non-vanishing net baryon-number density,”
arXiv:2212.09043.

[Proceedings]
M. Engelhardt, N. Hasan, T. Izubuchi, C. Kallidonis, S. Krieg, S. Meinel, J. Negele, A. Pochinsky, G. Silvi, and S. Syritsyn, “Transverse
momentum-dependent parton distributions for longitudinally polarized nucleons from domain wall fermion calculations at the physicalpion mass,” PoS LATTICE2022, 103 (2023).
P. Boyle, T. Izubuchi, L. Jin, C. Jung, C. Lehner, N. Matsumoto, and A. Tomiya, “Use of Schwinger-Dyson equation in constructing anapproximate trivializing map,” PoS LATTICE2022, 229 (2023).
J. S. Yoo, S. Syritsyn, Y. Aoki, P. Boyle, T. Izubuchi, and A. Soni, PoS LATTICE2021, 522 (2022).
J. S. Yoo, S. Syritsyn, Y. Aoki, P. Boyle, T. Izubuchi, and A. Soni, “Proton decay amplitudes with physical chirally-symmetric quarks ona lattice,” PoS PANIC2021, 443 (2022).
M. Tomii, T. Blum, D. Hoying, T. Izubuchi, L. Jin, C. Jung, and A. Soni, “K → ππ decay matrix elements at the physical point withperiodic boundary conditions,” PoS LATTICE2021, 394 (2022).
X. Feng, T. Izubuchi, L. Jin, and M. Golterman, “Pion electric polarizabilities from lattice QCD,” PoS LATTICE2021, 362 (2022).
M. Engelhardt, J. Green, N. Hasan, T. Izubuchi, C. Kallidonis, S. Krieg, S. Liuti, S. Meinel, J. Negele, and A. Pochinsky et al., PoS
LATTICE2021, 413 (2022).
S. Foreman, T. Izubuchi, L. Jin, X. Y. Jin, J. C. Osborn, and A. Tomiya, “HMC with normalizing ﬂows,” PoS LATTICE2021, 073 (2022).
M. Fukuma, N. Matsumoto, and Y. Namekawa, “Applying the worldvolume hybrid Monte Carlo method to lattice ﬁeld theories,” PoS
LATTICE2022, 011 (2023).
M. Fukuma, N. Matsumoto, and Y. Namekawa, “Numerical sign problem and the tempered Lefschetz thimble method,” PoS
CORFU2021, 254 (2022).
M. Fukuma and N. Matsumoto, “Tempered Lefschetz thimble method as a solution to the numerical sign problem,” J. Phys. Conf. Ser.
2207, 012054 (2022).
M. Fukuma and N. Matsumoto, “The basics and applications of the tempered Lefschetz thimble method for the numerical sign problem,”
PoS LATTICE2021, 395 (2022).
M. Fukuma, N. Matsumoto, and Y. Namekawa, “Worldvolume tempered Lefschetz thimble method and its error estimation,” PoS LATTICE2021, 446 (2022).
P. A. Boyle, D. Bollweg, C. Kelly, and A. Yamaguchi, “Algorithms for domain wall Fermions,” PoS LATTICE2021, 470 (2022).

Presentations[International Conferences/Workshops]
S. Syritsyn (invited), “Nucleon electromagnetic form factors at large momentum from lattice QCD,” Triangle Nuclear Theory Colloquium
at UNC Chapel Hill, November 29, 2022.
S. Syritsyn (invited), “Nucleon electromagnetic form factors at large momentum from lattice QCD,” Baryons 2022, Seville, Spain, November 7, 2022.
S. Syritsyn (invited), “Baryon number-violating amplitudes on a lattice with physical chirally-symmetric quarks,” 14th Conference on theIntersections of Particle and Nuclear Physics (CIPANP), Orlando, FL, August 31, 2022.
S. Syritsyn (invited), “Nucleon & nuclear structure inputs to beyond-SM searches,” SNOWMASS Rare Processes & Precision Frontier,Cincinnati, OH, May 17, 2022.
S. Syritsyn (invited), “Proton decay amplitudes with physical chirally-symmetric quarks,” BNL-HET & RBRC Joint Workshop“DWQ@25,” December 16, 2021.
S. Syritsyn (invited), “A more perfect universe: Role of lattice QCD in constraining violations of fundamental symmetries,” Physics &Astronomy Colloquium, Stony Brook University, November 9, 2021.
L. Jin (Invited), “The hadronic light-by-light scattering contribution to the muon g − 2,” χ QCD annual collaboration meeting, Online,
December 17, 2022.
L. Jin (Invited plenary talk), “Muon g − 2 from lattice QCD,” The 13th International Workshop on e + e− collisions from Phi to Psi, Online,
August 17, 2022.
L. Jin (Invited), “Lattice QCD input for the ﬁrst row CKM unitarity tests,” Seattle Snowmass Summer Meeting 2022, Online, July 19,
2022.
L. Jin (Invited), “Combining inﬁnite-volume photons and ﬁnite-volume hadronic matrix elements computed on the lattice,” QED in Weak
Decays, Higgs Centre for Theoretical Physics, JCMB, Online, June 24, 2022.
L. Jin (Invited), “The hadronic light-by-light scattering contribution to the muon g − 2 (RBC/UKQCD),” SchwingerFest 2022: muon g − 2,
Physics and Astronomy Building, Mani L. Bhaumik Institute, UCLA, June 17, 2022.
L. Jin (Invited), “QCD + QED studies,” USQCD All Hands’ Meeting 2022, MIT, Online, April 22, 2022.
L. Jin (Invited), “Lattice calculation of the pion mass splitting using the inﬁnite volume reconstruction method,” χ QCD annual collaboration meeting, Online, December 19, 2021.

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L. Jin, (Invited), “Attice calculation of the pion mass splitting using the inﬁnite volume reconstruction method,” BNL-HET & RBRC Joint
Workshop “DWQ@25,” Online, December 16, 2021.
L. Jin (Invited plenary talk), “Hadronic light-by-light contribution to muon g − 2,” The 10th International Workshop on Chiral Dynamics,
Institute of High Energy Physics (IHEP), CAS, Online, November 19, 2021.
L. Jin (Invited), “Lattice calculation of the muon g − 2,” The ﬁrst annual meeting of lattice QCD in China, Online, November 2, 2021.
L. Jin (Invited), “Lattice QCD input for the ﬁrst row CKM unitarity tests,” Fall Meeting of the Division of Nuclear Physics of the American
Physics Society, DNP 2021, Online, October 13, 2021.
L. Jin (Invited), “Lattice QCD results on the hadronic contributions to the muon g − 2,” The XXVIII International Conference on Supersymmetry and Uniﬁcation of Fundamental Interactions, SUSY 2021, Online, August 23, 2021.
L. Jin, “Pion electric polarizabilities from lattice QCD,” LATTICE 2021, MIT, Online, July 29, 2021.
L. Jin (Invited), “Lattice calculation of the hadronic light-by-light contribution to the muon g − 2 by the RBC-UKQCD collaborations,”
Muon g − 2 theory initiative workshop in memoriam of Simon Eidelman, KEK IPNS, High energy physics laboratory in Nagoya
University, Online, July 2, 2021.
L. Jin (Invited plenary talk), “Kaon decays from lattice QCD,” Flavor Physics and CP violation (FPCP), Online, June 9, 2021.
L. Jin (Invited), “Quark and lepton ﬂavor physics,” DOE Virtual Annual Progress Review of USQCD, Online, May 18, 2021.
N. Matsumoto, “Search for an eﬀective change of variable in QCD simulations,” DWQ@25, USA (BNL), Online, December 13, 2021.

[Seminars]
N. Matsumoto, “Sign problem and worldvolume tempered Lefschetz thimble method, RIKEN Radiation Laboratory,” Wako, Japan(RIKEN), Online, July 14, 2021.
N. Matsumoto, “Worldvolume tempered Lefschetz thimble method as an algorithm towards solving the sign problem,” RBRC seminar,
USA (BNL), Online, November 18, 2021.
N. Matsumoto, “Comment on the subtlety of deﬁning real-time path integral in lattice gauge theories,” Colorado University informal
seminar, Colorado, USA, Online, July 21 2022.
N. Matsumoto, “Comment on the subtlety of deﬁning real-time path integral in lattice gauge theories,” KEK theory seminar, Tsukuba,
Japan, Online, July 12, 2022.
N. Matsumoto, “Comment on the subtlety of deﬁning real-time path integral in lattice gauge theories,” Osaka University Particle Physics
Group seminar, Osaka, Japan, Online, November 8, 2022.
N. Matsumoto, “Use of Schwinger-Dyson equation in constructing an approximate trivializing map,” LATTICE 2022, Bonn, Germany,
August 8, 2022.
L. Jin, “Lattice calculations in muon g − 2,” Department of Physics and Astronomy, University of California, Davis, Online, May 3, 2021.
L. Jin, “Lattice calculations in muon g − 2,” Hadron mass and structure forum, Online, April 20, 2021.
L. Jin, “Lattice calculations in muon g − 2,” Institute of Theoretical Physics, Chinese Academy of Sciences, Online, April 15, 2021.
L. Jin, “Muon g − 2: hadronic light-by-light contribution and lattice QCD,” Muon g − 2 discussion forum, Peking University, Online,
April 13, 2021.

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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–with 2020 being the 30th years of continuous agreements between
RIKEN and RAL. The Facility enables muon science throughout Japan and other ﬁeld—it continues to attract proposals from a wide
variety of Japanese universities and institutions (with over 80 groups having now used the facility), and including industrial users suchat Toyota, and has been instrumental in establishing scientiﬁc links with other Asian universities.
Muons have their own spins with 100% polarization, and can detect local magnetic ﬁelds and their ﬂuctuations at muon stoppingsites very precisely. The method to study the characteristics of materials by observing time dependent changes of muon spin polarization is called “Muon Spin Rotation, Relaxation and Resonance” (µSR method), and is applied to study electro-magnetic properties
of insulating, metallic, magnetic and superconducting systems. Muons reveal static and dynamic properties of the electronic state ofmaterials in the zero-ﬁeld condition, which is the ideal magnetic condition for research into magnetism. For example, we have carriedout µSR investigations on a wide range of materials including frustrated pyrochlore systems, which have variety of exotic groundstates of magnetic spins, so the magnetism study of this system using muon is quite unique.
The ultra-cold muon beam can be stopped in thin foil, multi-layered materials and artiﬁcial lattices, which enables us to apply theaSR techniques to surface and interface science. The development of an ultra-cold muon beam is also very important as a source of
pencil-like small emittance muon beam for muon g − 2/EDM measurement. We have been developing muonium generators to create
more muonium atoms in vacuum even at room temperature to improve beam quality compared with the conventional hot-tungsten
muonium generator. We have demonstrated a strong increase in the muonium emission eﬃciency by fabricating ﬁne laser drill-holeson the surface of silica aerogel. We are also developing a high power Lyman-alpha laser in collaboration with the Advanced Photonics
group at RIKEN. The new laser will ionize muoniums 100 times more eﬃciently for slow muon beam generation.
Over the past 2–3 years, a signiﬁcant development activity in muon elemental analysis has taken place, proton radius experiments
have continued and been developed, and chip irradiation experiments have also continued.

2. Major Research Subjects
(1)
(2)
(3)
(4)

Materials science by muon-spin-relaxation method and muon site calculation
Development of elemental analysis using pulsed negative muons
Nuclear and particle physics studies via muonic atoms and ultra-cold muon beam
Other muon applications

3. Summary of Research Activity(1) Materials 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 up to 2022, following subjects of materiasl sciences are most importantachievements at the RIKEN-RAL muon facility:(1) Quasi magnetic monopole state in the Ru-based pyrochlore systems, R2 Ru2 O7 ;(2) Novel superconducting gap structure in the quasi two-dimensional organic superconductor, λ-(BETS)2 GaCl4 ;(3) Determination of muon positions estimated from density functional theory (DFT) and dipole-ﬁeld calculations;(4) Chemical muonic states in DNA molecules.
Result-1) Quasi magnetic monopole state in pyrochlore systems gave us new interpretations to understand exotic phenomena, likethe quantum spin liquid and spin fragmentation states. Result-2) A novel superconducting gap structure in the quasi two-dimensionalorganic superconductor, λ-(BETS)2 GaCl4 . An intermediate one-band superconducting gap-structure was conﬁrmed. Result-3) 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-4) Chemical states of the muon which attaches to DNA molecules were investigated by the avoided level-crossing muon-spin
resonance experiments. In conjunction with DFT calculations, we are trying to reveal the electron motion though the DNA molecule.
We have been continuing to develop muon-science activities in Asian countries. We enhanced international collaborations toorganize new µSR experimental groups and to develop muon-site calculation groups using computational method. We are creating
new collaborations with new teams in diﬀerent countries and also continuing collaborations in µSR experiments on strongly correlated
systems with researchers from Taiwan, Indonesia, China, Thailand and Malaysia including graduate students. We are starting to- 371 -

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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 centimeter in iron, silver and gold or over 4 cm in less dense materials such as carbon.
Some techniques for elemental analysis are destructive or require the material under investigation to undergo signiﬁcant treatment
and some of the techniques are only sensitive to the surface. Therefore, negative muons oﬀer a unique service in which they canmeasure inside, beyond the surface layer and completely non-destructively.
The areas of science that have used negative muons for elemental analysis have been very diverse. The largest area is the cultural
heritage community as the non-destructive ability is particularly important and will become more so. This community have investigated swords from diﬀerent eras, coins (Roman gold and silver, Islamic silver and from the Tudor Warship Mary Rose), miniatureboats from Sardinia, reliefs on Baptist church gate, Bronze Age tools and cannon balls. In addition, energy materials (Li composition
for hydrogen storage), bio-materials (search for iron to potentially help understand Alzheimer’s), engineering alloys (manufacturing
processes for new materials for jet engines), and functional materials (surface eﬀects in piezo electrics) have also been investigated.
The study was extended to see the diﬀerence by isotopes of silver and lead, which may give hint on the source of the material.
(3) Ultra-cold (low energy) muon beam generation and applications
Positive muon beam with thermal energy has been produced by laser ionization of muonium (bound system of µSR+ and electron)
emitted from a hot tungsten surface with stopping surface muon beam at Port-3. The method generates a positive muon beam withacceleration energy from several 100 eV to several 10 keV, small beam size (a few mm) and good time resolution (less than 8 nsec). By
stopping the ultra-cold muon beam in thin foil, multi-layered materials and artiﬁcial lattices, we can precisely measure local magnetic
ﬁeld in the materials, and apply the µSR techniques to surface and interface science. In addition, the ultra-cold muon is very importantas the source of pencil-like small emittance muon beam for muon g − 2/EDM measurement. It is essential to increase the slow
muon beam production eﬃciency by 100 times for these applications. There are three key techniques in ultra-cold muon generation:
production of thermal muonium, high intensity Lyman-alpha laser and the ultra-cold muon beam line.
A high-power Lyman-alpha laser was developed in collaboration with the Advanced Photonics group at RIKEN. The new laser
system is used at J-PARC U-line and, upon completion, will ionize muoniums 100 times more eﬃciently for slow muon beam
generation. In this development, we succeeded to synthesize novel ceramic-based Nd:YGAG and Nd:YSAG crystals, which realized
a highly eﬃcient and stable laser system. We are working hard to improve the homogeneity of large size crystals in order to achieve
full design power.
We also succeeded in developing an eﬃcient muonium generator, laser ablated silica aerogel, which emits more muoniums into
vacuum even at room temperature. Study has been done at TRIUMF utilizing positron tracking method of muon decay position.
We demonstrated in 2013 at least 10 times increase of the muonium emission eﬃciency by fabricating ﬁne laser drill-holes on thesurface of silica aerogel. Further study was carried out in 2017 to ﬁnd the optimum fabrication that will maximize the muonium
emission. From the analysis, we found the emission has large positive correlation with the laser ablated area rather than with anyother parameters. We also conﬁrmed the muon polarization in vacuum. An alternative detection method for muonium emission using
muonium spin rotation, which will be sensitive even to muoniums near the surface, was tested at RIKEN-RAL in 2018 and was foundsuccessful. The study was further applied to the measurement of the temperature dependence.
A new ultra-cold muon beam line for muon g − 2/EDM was constructed based on our various experience. The new beamline haslarger aperture for the beam, easier magnetic ﬁeld monitoring, active ﬁeld cancelling, and ﬁne beam control for the injection to RFQ
accelerator. The beamline is being tested at J-PARC S2 line.
(4) Other fundamental physics studies
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.
Preparation using muon beam is in progress. We measured the muon stopping distribution in low-density hydrogen-gas cell, whichgave us consistent results with beam simulation. Another key is the lifetime of the upper hyperﬁne state of the muonic hydrogen thatwill contribute the polarization. We successfully observed the clear muon spin precession of muonic deuterium atom in 2018 for theﬁrst time in the world. The measurement with muonic protium was carried out in 2019 and the data is being analyzed.
(5) Facility operation and refurbishment
The research activity at RIKEN-RAL had severe restriction in FY2021 also since the COVID-19 pandemic continued. It was impossible for users from outside RAL to carry out the experiment. Even though, we managed to carry out several µSR experiments withmailed samples. Since July 2021, RIKEN-RAL muon facility had been undergoing major refurbishment, ﬁrst time since its operationin 1994. The work coverd many important components, such as the cooling water circuit, vacuum system, radiation shielding, magnet- 372 -

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power supplies and power cables, detectors and beamline control system. Most of the works were completed by December 2022. We
had some test beam at the end of December and conﬁrmed that most of the beamline components are working ﬁne. As the ISIS beam
delivery in early 2023 was very limited, we are planning the full beam test in middle 2023.

Members
Director
Philip KING
Senior Research Scientist
Isao WATANABE
Contract Researcher
Katsuhiko ISHIDA

List of Publications & Presentations
Publications[Original Papers]
M. D. Umar, K. Ishida, R. Murayama, D. P. Sari, U. Widyaiswari, M. Fronzi, I. Watanabe, and M. Iwasaki, “Muon-spin motion at thecrossover regime between gaussian and lorentzian distribution of magnetic ﬁelds,” Prog. Theor. Exp. Phys. 2021, 083101 (2021).
W. N. Zaharim, S. N. A. Ahmad, S. Sulaiman, H. Rozak, D. F. H. Baseri, N. A. M. Rosli, S. S. Mohd-Tajudin, L. S. Ang, and I. Watanabe,“Density functional theory study of 12 mer single-strand guanine oligomer and associated muon hyperﬁne interaction,” ACS Omega 6,29641 (2021).
A. Jamaludin, W. N. Zaharim, S. Sulaiman, H. Rozak, A. L. Sin, and I. Watanabe, “Density functional theory investigation of muon
hyperﬁne interaction in guanine-cytosine double-strand DNA,” J. Phys. Soc. Jpn. 91, 024301 (2022).
S. Yoon, W. Lee, S. Lee, J. Park, H. Lee, Y. S. Choi, S. -H. Do, W. -J. Choi, W. -T. Chen, F. Chou, D. I. Gorbunov, Y. Oshima,
A. Ali, Y. Singh, A. Berlie, I. Watanabe, and K. -Y. Choi1, “Quantum disordered state in the J1 -J2 square-lattice antiferromagnet
Sr2 Cu(Te0.95 W0.05 )O6 ,” Phys. Rev. Res. 5, 014411 (2021).
Ce Zhang, T. Hiraki, K. Ishida, S. Kamal, S. Kamioka, T. Mibe, A. Olin, N. Saito, K. Suzuki, S. Uetake, and Y. Mao, “Modeling thediﬀusion of muonium in silica aerogel and its application to a novel design of multi-layer target for thermal muon generation,” Nucl.
Instrum. Methods Phys. Res. A 1042, 167443G (2022).
A. Green, K. Ishida, K. Domoney, T. Agoro, and A. D. Hillier, “Negative muons reveal the economic chaos of Rome’s AD 68/9 Civil
Wars,” Archaeol. Anthropol. Sci. 14, 165 (2022).

Presentations[International Conference/Workshop]
K. Ishida on behalf of the J-PARC muon g − 2/EDM collaboration (E34), “Muon g − 2/EDM experiment at J-PARC,” Fifth Plenary
Workshop of the Muon g − 2 Theory Initiative, UK (The University of Edinburgh), September 5–9, 2022.

[Domestic Conferences/Workshops]

石田勝彦, 「ラザフォードアップルトン研究所ミュオン施設の紹介」, 第 7 回文理融合シンポジウム 量子ビームで歴史を探る—加速器が紡ぐ文理融合の地平—, つくば市 (KEK), 2022 年 11 月 3 日.
石田勝彦, 「ミュオン触媒核融合の利用」, 中間子科学の将来討論会, 和光市 (理研), 2022 年 11 月 9–11 日.
石田勝彦, 「理研 RAL 施設と原子・原子核研究」, 第 13 回 muon 科学と加速器研究研究会, 和光市 (理研), 2023 年 1 月 10–11 日.

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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)
(2)
(3)
(4)

Safety management at radiation facilities of Nishina Center for Accelerator-Based Science
Safety management at Radioisotope Center
Radiation shielding design and development of accelerator safety system
Obtaining permissions for changes accelerators and use of radioisotopes

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.
Permissions from Nuclear Regulation Authority of Japan for the Radioisotope Production beamline and additional quantity of
unsealed radioisotope astatine-211 was obtained. Safety measures were conducted in the Radioisotope Experimental building owing
to the increased use of alpha-emitting nuclides. Measures for the Covid-19 infection in Nishina center were also conducted. A ﬁredrill by a small group of emergency response personnel assuming Saturday, Sunday and nighttime hours were carried out with thegeneral aﬀairs section in RIKEN.

Members
Director
Kanenobu TANAKA
Technical Scientists
Rieko HIGURASHI
Hisao SAKAMOTO

Hiroki Mukai

Expert Technician
Atsuko AKASHIO
Visiting Scientists
Toshiya SANAMI (KEK)
Kenta SUGIHARA (KEK)
Hiroshi YASHIMA (Kyoto Univ.)

Nobuhiro SHIGYO (Kyushu Univ.)
Eunji LEE (KEK)

Administrative Part-time Workers
Kimie IGARASHI
Satomi IIZUKA
Miyabi MURATA

Naoko USUDATE
Tokie KUDO

Temporary Staﬃng
Ryuji SUZUKI
Assistant
Tomomi OKAYASU

List of Publications & Presentations
Publications[Original Papers]
K. Sugihara, N. Shigyo, A. Akashio, and K. Tanaka, “Measurement of neutron energy spectra of 345 MeV/nucleon 238 U incidence on acopper target,” Nucl. Instrum. Methods Phys. Res. B 512, 102 (2022).
K. Sugihara, N. Shigyo, E. Lee, T. Sanami, and K. Tanaka, “Measurement of thick target neutron yields from 7 MeV/nucleon α incidence
on 209 Bi,” Nucl. Instrum. Methods Phys. Res. B 470, 15 (2020).

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Presentations[International Conferences/Workshops]
K. Tanaka (plenary), “Resent ﬁre protection status at RIKEN RIBF cyclotron facility,” International Technical Safety Forum (ITSF2022),
Meyrin, Switzerland, October 24–28, 2022.
K. Sugihara (plenary), N. Shigyo, A. Akashio, and K. Tanaka, “Measurement of neutron production yields of 345 MeV/nucleon 238 U +Cu with a time-of-ﬂight method,” 15th workshop on Shielding aspects of Accelerators, Tagets, and Irradiation Facilties (SATIF-15),
Michigan, USA, September 20–23, 2022.

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User Liaison Group
1. Abstract

The User Liaison Group is engaged in activities to promote the eﬃcient and wide-ranging use of the RIBF accelerator facility.
The Group has two teams, the RIBF User Liaison Team and the Outreach Team, to carry out these tasks.
The main activities of the RIBF User Liaison Team include i) organizing the International Program Advisory Committees to review
scientiﬁc experimental proposals to use RIBF, ii) management of beamtime for eﬃcient use of RIBF, iii) acceptance of researchers
from outside RIKEN based on the “RIBF Independent User” system established to promote the use of RIBF, and iv) operation of the
RIBF Users Oﬃce to provide RIBF Independent Users with one-stop processing of various procedures for the use of RIBF.
The Outreach Team has created various information materials, such as pamphlets, posters, and homepages, to introduce theresearch activities in the RNC. On the homepage, we provide information on usage of the RIBF facility. The team also participate inscience introduction events hosted by public institutions. In addition, the Team also takes care of laboratory tours for RIBF visitorsfrom public.

Members
Director
Hideki UENO
Assistants
Yu NAYA
Tomomi OKAYASU

Asako TAKAHASHI- 376 -

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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 ofcontact 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, 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 PAC
meeting is organized once a year regularly, and the ML PAC meetings are organized once or 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.

MemberTeam Leader
Ken-ichiro YONEDA- 377 -

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User Liaison Group
Outreach Team
1. Abstract

The mission of the Outreach Team is to provide various “intangible” technical support for the dissemination of information on
the research in the RNC. For instance, the team creates brochures introducing the RNC and the RIBF accelerator facility, posters of
symposia and the summer school hosted by the RNC, the center homepage containing information such as details of the RNC and theprocedure for the use of the RIBF facility, and images of equipment and facilities available for researchers inside and outside RIKEN,
among the others. Furthermore, the team also participates in 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 the RNC, through the creation of various materials
such as brochures, websites, posters, and videos, among the others. The arrangement of tours of the RIBF facility and the exhibition and introduction 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 theorganization and its research activities. This website plays an important role in providing information to researchers who visit
the RNC to conduct his/her own research.
• [Pamphlets] The Team has produced various pamphlets introducing the organization of and the studies performed at RNC. The
pamphlet 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. As a related eﬀort, a notebook for elementary school students featuring
RIBF was produced in FY2022. The notebooks will be distributed to elementary school students• [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.
Although the number of visitors has not yet reached this level, the number of RIBF tour participants showed a recovery trend in
FY2022 as the situation in COVID19 improved.
• [Science event participation] In 2010, 2012, 2013, 2015, and 2016, the Team opened an exhibition booth of RNC to introduce thelatest research activities on the occasion of the “Science Agora” organized by Japan Science and Technology Agency (JST). From
time to time, the 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.
For FY2022, the Team did not exhibit at these events, but provided technical assistance to online participants at an event for
students held at the RNC.
• [RIKEN Wako Open Campus] In the FY2022 Open Campus, the Team continued to produce all videos to introduce RIBF for
online viewing as did last year. The RIBF facility tour was also conducted with a limited number of visitors, with COVID-19
infection control measures in place. Not only the Team, but also almost all members of the User Liaison Group cooperated in thetour event.
• [Yoshio Nishina Memorial Oﬃce Unveiling Ceremony] The “Yoshio Nishina Memorial Oﬃce Unveiling Ceremony” and the
Symposium “Trajectory/Miracle of the RIKEN Yoshio Nishina Laboratory” were held at the RNC on October 28, 2022. The
Team has been involved in the preparation of the ceremony from the beginning, producing pamphlets and commemorative items.
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.

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Members
Team Leader
Hideki UENO
Technical Staﬀ
Narumasa MIYAUCHISpecial Temporary Research Scientist
Yasushi WATANABE- 379 -

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Oﬃce of the Center Director
1. Abstract

This oﬃce is in place from JFY2018 to conduct works that the Center Director deems necessary for the operation of the research
center and the secretarial work related to the research center in general.

2. Major Work Contents• Nishina Center Monthly Meeting
The purpose of the meeting is to share information on activities within the Nishina Center with all of the members. The meetingcovers introduction of newcomers, press-released achievements, announcement of events organized by or related to the Nishina
Center, safety issues, and others to be informed to all members. The meeting agenda is distributed to all of the members via
mailing-list.
• Conference Support
Assistant staﬀ members support coherently a large-size conference hosted by the Nishina Center.
• Orientation for newcomers to the Nishina Center
The Orientation is organized once a year to the newcomers to give instructions for emergency response, safety in research,
computer and network resources and security, and research misconduct prevention.

3. Summary of Work Activity• Nishina Center Monthly Meeting
Noriko Asakawa arranged the agenda and Hidetada Baba supported the on-line video system for the meeting.
– The 179th, April 13, 2022
(1) Greetings from the RNC Director to kick oﬀ the new ﬁscal year(2) Introduction of newcomers(3) Awards
RIKEN Eiho Award, RIKEN Baiho Award, RIKEN Ohbu Award, PTEP Editors’ Choice(4) Report from the RNC Director– The 180th, May 11, 2022
(1) Introduction of newcomers(2) Award
Saruhashi Prize(3) Report on RIKEN Open Day(4) Press release
Superconducting Ring Cyclotron has been registered in Guinness World Records™!
“α-Clustering in Atomic Nuclei from First Principles with Statistical Learning and the Hoyle State character”“First Application of Mass Measurement with the Rare-RI Ring Reveals the Solar r-Process Abundance Trend at
A = 122 and A = 123”
(5) Report from the RNC Director– The 181st, June 8, 2022
(1) Introduction of newcomers(2) Farewell speech(3) Award 2021 Wada Memorial Award(4) Nishina Laboratory room reproduction
Information on related events(5) Report on “Physics of RI: Recent progress and perspectives”(6) Report from the RNC Director– The 182nd, July 13, 2022
(1) Introduction of newcomers(2) Report from the Nishina Center and iTHEMS Promotion Oﬃce(3) AwardFriedrich Wilhelm Bessel Research Award(4) Press release“Observation of a correlated free four-neutron system”(5) Diversity promotion activity report
Website of the Nishina Center Cheering Squad(6) Report from the RNC Director– The 183rd, September 5, 2022
(1) Introduction of newcomers(2) Report on “Accelerator Kitchen”(3) Request for donations for the Yoshio Nishina Memorial Project- 380 -

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RIKEN Accel. Prog. Rep. 56 (2023)(4) Space for external users(5) Report from the RNC Director– The 184th, October 12, 2022
(1) Self-introduction by newly appointed personnel(2) Introduction of newcomer(3) RIBF Thesis Award(4) Report from the RNC Director– The 185th, November 9, 2022
(1) Award
Japanese Society of Crop Science Best Paper Award(2) Press release“β-Delayed One and Two Neutron Emission Probabilities South-East of 132 Sn and the Odd-Even Systematics inr-Process Nuclide Abundances”(3) The 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS2022)(4) Report from the RNC Director– The 186th, December 9, 2022
(1) Award
The Outstanding Presentation Award presented at the 65th Radiation Chemistry Forum(2) Press release“Discovery of 39 Na”(3) Report from the RNC Director(4) RIKEN Accelerator Progress Report– The 187th, January 16, 2023
(1) New Year’s Greeting from the RNC Director(2) Press Release“Study of the N = 32 and N = 34 Shell Gap for Ti and V by the First High-Precision Multireﬂection Time-of-Flight
Mass Measurements at BigRIPS-SLOWRI”(3) Report from the RNC Director– The 188th, February 8, 2023
(1) INTT of sPHENIX(2) Nishina Center Library (archives)(3) Simpliﬁed ﬁre drill on February 21, 2023
(4) Industry Membership to Create the Future with RIKEN(5) Report from the RNC Director– The 189th, March 8, 2023
(1) Press release“Long-Term Density Trend in the Mesosphere and Lower Thermosphere from Occultations of the Crab Nebulawith X-Ray Astronomy Satellites”(2) Report from the RNC Director(3) Other(4) Farewell greetings• Conference Support
No large size conferences hosted by the Nishina Center were organized.
• Orientation for newcomers to the Nishina Center
The Orientation was organized on April 15, 2022.

Members
Director
Motohide YOKOTA
Research Administrator
Narumasa MIYAUCHI
Assistants
Noriko ASAKAWA
Yu NAYA
Asako SAKIHAMA
Karen SAKUMA

Asako TAKAHASHI
Mitsue YAMAMOTO
Izumi YOSHIDA- 381 -

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Partner Institutions
The RIKEN Nishina Center for Accelerator-Based Science (RNC) has collaborated with universities and research institutes since2008 under the research partnership agreement. This collaboration framework permits an external institute to develop its own projects
at the RIKEN Wako Campus in equal partnership with the RNC. At present, two institutes—the Center for Nuclear Study (CNS), theUniversity of Tokyo and the Wako Nuclear Science Center (WNSC), Institute of Particle and Nuclear Studies (IPNS), High Energy
Accelerator Research Organization (KEK)—are conducting joint research under the research partnership agreement.
The CNS and RNC signed the research partnership agreement in 2008. Until then, the CNS had collaborated in joint programswith RIKEN under the “Research Collaboration Agreement on Heavy Ion Physics” (collaboration agreement) signed in 1998. The
partnership agreement redeﬁnes procedures related to the joint programs while keeping the spirit of the collaboration agreement. The
joint programs include experimental nuclear-physics activities using CRIB, SHARAQ, OEDO, and GRAPE at the RI Beam Factory(RIBF), accelerator developments, and activities at RHIC PHENIX.
The KEK-WNSC and RNC signed a research partnership agreement on “Low-Energy Unstable Nuclear Beam Science” in 2011.
The joint experimental programs are based on the KEK Isotope Separation System (KISS). The KISS has been available for RIBF
users since 2015. The research collaboration agreement for the SLOWRI facility and the multi-reﬂection time-of-ﬂight (MRTOF)
mass spectrograph was then signed in 2019, based on which the SLOWRI Joint Operation Committee has been established for thecollaborative use and operation of the SLOWRI facility.
Experimental proposals that request the use of the above-noted devices of the CNS and KEK, together with other key devices at
the RIBF, are screened by the Program Advisory Committee for Nuclear Physics experiments at the RIBF (NP-PAC). The NP-PAC
meetings are co-hosted by the CNS and KEK.
Matters necessary for the smooth promotion of joint research based on the research partner agreement are determined at the Collaboration Liaison Council. More speciﬁc matters related to the execution of collaborative research are discussed at the Collaboration
Liaison Committee established under the Liaison Council. In order to enhance the eﬀectiveness of coordination and information sharing on joint research programs, the Joint Researchers Meeting was established in 2020 under the Collaboration Liaison Committee.
Several members of both institutes have also been invited to participate as external members in RNC committees related to theoperation of the RIBF, such as the Machine-Time Committee and the Safety Review Committee.
The activities of the CNS and KEK are reported in the succeeding pages.

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Partner Institution
Center for Nuclear Study, Graduate School of Science
The University of Tokyo
1. Abstract

The Center for Nuclear Study (CNS) aims to elucidate the nature of nuclear system by producing the characteristic states where
the Isospin, Spin and Quark degrees of freedom play central roles. These researches in CNS lead to the understanding of the matterbased on common natures of many-body systems in various phases. We also aim at elucidating the explosion phenomena and theevolution of the universe by the direct measurements simulating nuclear reactions in the universe. In order to advance the nuclear
science with heavy-ion reactions, we develop AVF upgrade, CRIB and SHARAQ facilities in the large-scale accelerators laboratories
RIBF. The OEDO facility has been developed as an upgrade of the SHARAQ, where a RF deﬂector system has been introduced toobtain a good quality of low-energy beam. A new project for fundamental symmetry using heavy RIs has been starting to install new
experimental devices in the RIBF. We promote collaboration programs at RIBF as well as RHIC-PHENIX and ALICE-LHC with
scientists in the world, and host international meetings and conferences. We also provide educational opportunities to young scientists
in the heavy-ion science through the graduate course as a member of the department of physics in the University of Tokyo and throughhosting the international summer school.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)

Accelerator Physics
Nuclear Astrophysics
DONUTS/NUSPEQ
Quark physics
Nuclear Theory
OEDO/SHARAQ project
Exotic Nuclear Reaction
Fundamental Physics

3. Summary of Research Activity(1) Accelerator Physics
One of the major tasks of the accelerator group is the development of ion sources and the optimization of the beam transport system
for the experimental devices installed in the E7 experiment room. In 2022, HyperECR ion source was operated for 2,151 hours. A
new method for sustainable magnesium beam production was put into practical use for CRIB. The 24 Mg8+ beam was successfully
produced for 18 days with four breaks to reﬁll the sample crucible. In a university-industry collaboration, a magnetic design for a new
ECR ion source was proposed for industrial applications. For the development of the pepper-pot emittance monitor to diagnose thebeam extracted from AVF cyclotron, an optical system with a digital camera was completed. Then, the required angular accuracy wasestimated to be less than 0.3 mrad. The beam test for the prototype was planned and the preparation was started.
(2) Nuclear astrophysics
The main activity of the nuclear astrophysics group is to study astrophysical reactions and special nuclear structure, such as
clusters, using the low-energy RI beam separator CRIB. In October 2022, a 6 He radioactive beam was produced for the second time at
CRIB, with imporved beam intensity and purity by introducing wire chambers (MWDC) and a degrader. In Mar 2023, we performeda direct measurement of astrophysical 14 O(α, p) reaction in an international collaboration with the groups in IBS (Korea), Texas A&M
University (US) and others. An active-target system developed in Texas (TexAT) was brought to Japan to perform this measurementwith the thick-target method using the 14 O radioactive beam at CRIB. This was the ﬁrst experiment at CRIB with participants fromforeign countries after the pandemic.
(3) DONUTS/NUSPEQThe Low Energy Nuclear Reaction group studies exotic structures in high-isospin and/or high-spin states in nuclei. In the springof 2022, two nuclear reactions, 130 Sn(d, p) and 56 Ni(d, p), SHARAQ18 and 19, respectively, were performed at the OEDO-SHARAQ
system in inverse kinematics by employing the surrogate technique, where the decay channels of the unbound states were identiﬁed
directly from the measurement of reaction residues. Prior to the SHRAQ18, MS22-01 was carried out to establish a new optics fortransporting the ion beam with better transmission. In winter 2022, another OEDO experiment, SHARAQ12, for the single particle
structure in 51 Ca was partially performed. The analyses of the experiments, ImPACT17-02-01, -02, and SHARAQ11, 4 He(8 He, 8 Be)4nreaction, are in progress. The analysis of the groundbreaking experiment on the inelastic decay from the isobaric analog resonancesis almost ﬁnished. The CNS GRAPE (Gamma-Ray detector Array with Position and Energy sensitivity) is a major instrument for
high-resolution in-beam gamma-ray spectroscopy. The digital signal processing equipment for the GRAPE is under development.
(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- 384 -

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RIKEN Accel. Prog. Rep. 56 (2023)

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 collisions, the measurement oflong range two particle correlations in p-Pb collisions, searches for thermal photons in high multiplicity pp collisions. The group
has involved in the ALICE-TPC upgrade using a Gas Electron Multiplier (GEM), where the group is very active in the development
and benchmarking of the online space-charge distortion corrections using machine learning techniques running on the GraphicalProcessing Unit (GPU). The group has started simulation studies for the ALICE 3 future upgrade.
(5) Nuclear Theory
The nuclear theory group is conducting large-scale shell-model calculations, having a strong relationship to the project “Programfor Promoting Researches on the Supercomputer Fugaku.” One of the key achievements in FY2022 is ﬁnding the mechanism of thestrongly hindered E0 transition from the superdeformed 0+ state to the ground state in 40 Ca. We are also performing shell-model
calculations for the structure of neutron-rich nuclei in collaboration with experiments carried out in RIBF, RIKEN, focusing on theregion around 54 Ca. Another important direction of our activity is application to the fundamental physics. In this year, we have foundthat the nuclear Schiﬀ moment is strongly correlated to nuclear magnetic moments, which enables providing reliable Schiﬀ moments
in comparson to existing data.
(6) OEDO/SHARAQ project
The OEDO/SHARAQ group pursues experimental studies with RI beams by using the high-resolution beamline and the SHARAQ
spectrometer, and the OEDO for the decelerated RI beams. The uniqueness of the OEDO-SHARAQ system is its versatile performancein low-energy RI production and high-resolution spectroscopy. In FY2022, taking advantage of this feature, two low-energy RI
experiments for (d, p)-type surrogate reactions and a high-resolution direct mass measurement for two-proton radioactivity were
performed. Through the measurements, we were able to demonstrate a smooth re-arrangement of the beamline and experimental
detector setups. In addition, we installed an active stopper detector and γ-ray detectors for the in-ﬂight isomeric tagging of exotic
nuclei in the mass measurement program. Data analysis of performed experiments is ongoing. The experimental study of 0− strengthin nuclei using the parity-transfer charge exchange (16 O, 16 F) is in the ﬁnal stage. The results of the ﬁrst and second experiments with
the OEDO system for LLFPs will be completed and reported soon.
(7) Exotic Nuclear Reaction
The Exotic Nuclear Reaction group studies various exotic reactions induced by heavy-ion beams. We proceeded with the data
reduction of the double charge exchange (12 C,12 Be) reaction taken in the previous year for a search of double Gamow-Teller resonance.
(8) Fundamental Physics
The development of the quantum sensor to search for a permanent electric dipole moment (EDM) with an optical lattice interferometer is in progress at RIKEN. The RF ﬁlter was newly developed and installed to the beam transport system to obtain the secondary
beam of the Fr ion with a high purity, which was used to improve the trapping eﬃciency of the magneto-optical trap. The parametertuning to get high intensity cold Fr atoms in the MOT is continued. Furthermore, a homemade Yb-doped ﬁber ampliﬁer (YDFA) isdeveloped, required to generate a deep optical lattice potential that would enable a long interrogation time for the EDM measurement.

Members
Director
Yasuhiro SAKEMI
Scientiﬁc Staﬀs
Yasuhiro SAKEMI (Professor)
Kentaro YAKO (Associate Professor)
Nobuaki IMAI (Associate Professor)
Taku GUNJI (Associate Professor)

Hidetoshi YAMAGUCHI (Lecturer)
Shin’ichiro MICHIMASA (Assistant Professor)
Hiroki NAGAHAMA (Assistant Professor)
Noritaka KITAMURA (Assistant Professor)

Visiting Scientists
Yutaka UTSUNO (Visiting Professor)
Daiki NISHIMURA (Visiting Associate Professor)
Toshitaka KAJINO (Visiting Researcher)
Ikuko HAMAMOTO (Visiting Researcher)
Jongwon HWANG (Visiting Researcher)

Takahide NAKAGAWA (Visiting Researcher)
Susumu SHIMOURA (Visiting Researcher)
Noritaka SHIMIZU (Visiting Researcher)
Shinsuke OTA (Visiting Researcher)
Masanori DOZONO (Visiting Researcher)Academic Specialist
Reiko KOJIMA- 385 -

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RIKEN Accel. Prog. Rep. 56 (2023)

Technical Specialist
Yasuteru KOTAKA
Techinical Assistant
Masayoshi YAGYU
Project Research Associates
Seiya HAYAKAWA
Daiki SEKIHATARin YOKOYAMA

Post Doctoral Associates
Keisuke NAKAMURA
Keita KAMAKURA
Nanru MA

Kota YANASE
Thomas William CHILLERY
Takeshi SAITOAssistant Teaching Staﬀs
Yuko SEKIGUCHI
Keita KAWATA
Akane SAKAUE

Shoichiro MASUOKA
Hikari MURAKAMI

Graduate Students
Hideki SHIMIZU
Naoya OZAWA
Shutaro HANAI
Shintaro NAGASE
Ryotaro KOHARA
Jiatai LI

Daisuke UEHARA
Kodai OKAWA
Hitoshi BABA
Mirai FUKASE
Shujiro SINDO

Administration Staﬀs
Noriko SHIMANE
Ikuko YAMAMOTO

Yukino KISHI
Aki KOTAKA

List of Publications & Presentations
Publications[Original Papers]
L. Yang, C. J. Lin, H. Yamaguchi, A. M. Moro, N. R. Ma, D. X. Wang, K. J. Cook, M. Mazzocco, P. W. Wen, S. Hayakawa, J. S. Wang,
Y. Y. Yang, G. L. Zhang, Z. Huang, A. Inoue, H. M. Jia, D. Kahl, A. Kim, M. S. Kwag, M. L. Commara, G. M. Gu, S. Okamoto,
C. Parascandolo, D. Pierroutsakou, H. Shimizu, H. H. Sun, M. L. Wang, F. Yang, and F. P. Zhong, “Breakup of the proton halo nucleus
8
B near barrier energies,” Nat. Commun. 13, 7193 (2022).
N. J. Abdulameer et al. [PHENIX], “Improving constraints on gluon√ spin-momentum correlations in transversely polarized protons via
midrapidity open-heavy-ﬂavor electrons in p↑ + p collisions at s = 200 GeV,” Phys. Rev. D 107, 052012 (2023).
√
N. J. Abdulameer et al. [PHENIX], “Low-pT direct-photon production in Au + Au collisions at sNN = 39 and 62.4 GeV,” Phys. Rev. C
107, 024914 (2023).
N. J. Abdulameer et al. [PHENIX], “Measurements of second-harmonic Fourier coeﬃcients from azimuthal anisotropies in p + p, p +√Au, d + Au, and 3 He + Au collisions at sNN = 200 GeV,” Phys. Rev. C 107, 024907 (2023).
√
U. Acharya et al. [PHENIX], “Study of ϕ-meson production in p + Al, p + Au, d + Au, and 3 He + Au collisions at sNN = 200 GeV,”
Phys. Rev. C 106, 014908 (2022).
U. A. Acharya et al. [PHENIX], “Measurement of ψ(2S ) nuclear modiﬁcation at backward and forward rapidity in p + p, p + Al, and p√+ Au collisions at sNN = 200 GeV,” Phys. Rev. C 105, 064912 (2022).
S. Acharya et al. [ALICE], “Measurement of anti-3 He nuclei absorption in matter and impact on their propagation in the Galaxy,” Nat.
Phys. 19, 61 (2023).
√
S. Acharya et al. [ALICE], “Multiplicity dependence of charged-particle jet production in pp collisions at s = 13 TeV,” Eur. Phys. J. C
82, 514 (2022).
√
S. Acharya et al. [ALICE], “Measurement of beauty production via non-prompt D0 mesons in Pb–Pb collisions at sNN = 5.02 TeV,” J.
High Energy Phys. 12, 126 (2022).
S. Acharya et al. [ALICE], “First study of the two-body scattering involving charm hadrons,” Phys. Rev. D 106, 052010 (2022).
√
S. Acharya et al. [ALICE], “Forward rapidity J/ψ production as a function of charged-particle multiplicity in pp collisions at s = 5.02
and 13 TeV,” J. High Energy Phys. 06, 015 (2022).
√
S. Acharya et al. [ALICE], “Neutral to charged kaon yield ﬂuctuations in Pb–Pb collisions at sNN = 2.76 TeV,” Phys. Lett. B 832,
137242 (2022).

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U. A. Acharya √et al. [PHENIX], “Transverse-single-spin asymmetries of charged pions at midrapidity in transversely polarized p + p
collisions at s = 200 GeV,” Phys. Rev. D 105, 032003 (2022).
√
S. Acharya et al. [ALICE], “Production of light (anti)nuclei in pp collisions at s = 5.02 TeV,” Eur. Phys. J. C 82, 289 (2022).
S. Acharya et al. [ALICE],“Observation of a multiplicity dependence in the pT -diﬀerential charm baryon-to-meson ratios in proton√
proton collisions at s = 13 TeV,” Phys. Lett. B 829, 137065 (2022).
S. Acharya et al. [ALICE], “K0S K0S and K0S K± femtoscopy in pp collisions at s = 5.02 and 13 TeV,” Phys. Lett. B 833, 137335 (2022).
S. Acharya et al. [ALICE], “Characterizing the initial conditions of heavy-ion collisions at the LHC with mean transverse momentum
and anisotropic ﬂow correlations,” Phys. Lett. B 834, 137393 (2022).
√
U. A. Acharya et al. [PHENIX], “Systematic study of nuclear eﬀects in p + Al, p + Au, d + Au, and 3 He + Au collisions at sNN =0
200 GeV using π production,” Phys. Rev. C 105, 064902 (2022).
S. Acharya et al. [ALICE], “Investigating
charm production and fragmentation via azimuthal correlations of prompt D mesons with√charged particles in pp collisions at s = 13 TeV,” Eur. Phys. J. C 82, 335 (2022).
√
S. Acharya et al. [ALICE], “Measurement of prompt D+s -meson production and azimuthal anisotropy in Pb–Pb collisions at sNN =5.02 TeV,” Phys. Lett. B 827, 136986 (2022).
√
S. Acharya et al. [ALICE], “Prompt D0 , D+ , and D∗+ production in Pb–Pb collisions at sNN = 5.02 TeV,” J. High Energy Phys. 01, 174(2022).
U. A. Acharya et al. [PHENIX], “Transverse single spin asymmetries of forward neutrons in p + p, p + Al and p + Au collisions at√
sNN = 200 GeV as a function of transverse and longitudinal momenta,” Phys. Rev. D 105, 032004 (2022).
√
S. Acharya et al. [ALICE], “General balance functions of identiﬁed charged hadron pairs of (π, K, p) in Pb–Pb collisions at sNN =2.76 TeV,” Phys. Lett. B 833, 137338 (2022).
√
S. Acharya et al. [ALICE], “Measurement of inclusive charged-particle b-jet production in pp and p–Pb collisions at sNN = 5.02 TeV,”
J. High Energy Phys. 01, 178 (2022).
√
S. Acharya et al. [ALICE], “Inclusive quarkonium production in pp collisions at s = 5.02 TeV,” Eur. Phys. J. C 83, 61 (2023).
√
S. Acharya et al. [ALICE], “Production of light (anti)nuclei in pp collisions at s = 13 TeV,” J. High Energy Phys. 01, 106 (2022).
√
S. Acharya et al. [ALICE], “Prompt and non-prompt J/ψ production cross sections at midrapidity in proton-proton collisions at s = 5.02
and 13 TeV,” J. High Energy Phys. 03, 190 (2022).
S. Acharya et al. [A Large Ion Collider Experiment and ALICE], “Measurement of the groomed jet radius and momentum splitting√
fraction in pp and Pb–Pb collisions at sNN = 5.02 TeV,” Phys. Rev. Lett. 128, 102001 (2022).
√
S. Acharya et al. [ALICE], “Measurements of the groomed and ungroomed jet angularities in pp collisions at s = 5.02 TeV,” J. HighEnergy Phys. 05, 061 (2022).
√
S. Acharya et al. [ALICE], “Polarization of Λ and Λ̄ Hyperons along the Beam Direction in Pb–Pb Collisions at sNN = 5.02 TeV,”
Phys. Rev. Lett. 128, 172005 (2022).
√
S. Acharya et al. [A Large Ion Collider Experiment and ALICE], “Hypertriton Production in p–Pb Collisions at sNN = 5.02 TeV,” Phys.
Rev. Lett. 128, 252003 (2022).
S. Acharya et al. [ALICE], “Study of very forward energy and its correlation with particle production at midrapidity in pp and p–Pb
collisions at the LHC,” J. High Energy Phys. 08, 086 (2022).
√
U. A. Acharya et al. [PHENIX], “Kinematic dependence of azimuthal anisotropies in p + Au, d + Au, and 3 He + Au at sNN = 200 GeV,”
Phys. Rev. C 105, 024901 (2022).
√
S. Acharya et al. [ALICE], “Production of K∗ (892)0 and ϕ(1020) in pp and Pb–Pb collisions at sNN = 5.02 TeV,” Phys. Rev. C 106,034907 (2022).
S. Acharya et al. [ALICE], “Direct observation of the dead-cone eﬀect in quantum chromodynamics,” Nature 605, 440 (2022). [erratum:
Nature 607, E22 (2022)]√(2455) Production in Proton–Proton Collisions at s = 13 TeV,”
S. Acharya et al. [ALICE], “Measurement of Prompt D0 , Λ+c , and Σ0,++c
Phys. Rev. Lett. 128, 012001 (2022).
S. Acharya et al. [ALICE], “Charm-quark fragmentation fractions and production cross section at midrapidity in pp collisions at the
LHC,” Phys. Rev. D 105, L011103 (2022).
S. Acharya et al. [ALICE], “Measurement of K∗ (892)± production in inelastic pp collisions at the LHC,” Phys. Lett. B 828, 137013(2022).
√
S. Acharya et al. [ALICE], “Inclusive, prompt and non-prompt J/ψ production at midrapidity in p-Pb collisions at sNN = 5.02 TeV,” J.
High Energy Phys. 06, 011 (2022).
S. Acharya et al. [ALICE], “Investigating the role of strangeness in baryon–antibaryon annihilation at the LHC,” Phys. Lett. B 829,
137060 (2022).
√√
S. Acharya et al. [ALICE], “Production of Λ and K s0 in jets in p–Pb collisions at sNN = 5.02 TeV and pp collisions at s = 7 TeV,”
Phys. Lett. B 827, 136984 (2022).
S. Acharya et al. [ALICE], “Exploring the NΛ–NΣ coupled system with high precision correlation techniques at the LHC,” Phys. Lett. B
833, 137272 (2022).
S. Acharya et al. [ALICE], “Nuclear modiﬁcation factor of light neutral-meson spectra up to high transverse momentum in p–Pb collisions√
at sNN = 8.16 TeV,” Phys. Lett. B 827, 136943 (2022).
T. Otsuka, T. Abe, T. Yoshida, Y. Tsunoda, N. Shimizu, N. Itagaki, Y. Utsuno, J. Vary, P. Maris, and H. Ueno, “α-Clustering in atomic
nuclei from ﬁrst principles with statistical learning and the hoyle state character,” Nat. Commun. 13, 2234 (2022).

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E. Ideguchi, T. Kibedi, J. Dowie, H. T. Hoang, Kumar Raju M., G. Lane, L. Bignell, T. K. Eriksen, A. J. Mitchell, A. Akber, B. Combes,
B. McCormik, T. Gray, A. Stuchbery, N. Shimizu, and Y. Utsuno, “Electric monopole transition from the superdeformed band in 40 Ca,”
Phys. Rev. Lett. 128, 252501 (2022).
N. Shimizu and Y. Tsunoda, “SO(3) quadratures in angular-momentum projection,” Comput. Phys. Commun. 283, 108583 (2022).
D. Little, A. D. Ayangeakaa, R. V. F. Janssens, S. Zhu, Y. Tsunoda, T. Otsuka, B. A. Brown, M. P. Carpenter, A. Gade, D. Rhodes,
C. R. Hoﬀman, F. G. Kondev, T. Lauritsen, D. Seweryniak, J. Wu, J. Henderson, C. Y. Wu, P. Chowdhury, P. C. Bender, A. M. Forney,
and W. B. Walters, “Multistep Coulomb excitation of 64 Ni: Shape coexistence and nature of low-spin excitations,” Phys. Rev. C 106,
044313 (2022).
V. Tripathi, S. Bhattacharya, E. Rubino, C. Benetti, J. F. Perello, S. L. Tabor, S. N. Liddick, P. C. Bender, M. P. Carpenter, J. J. Carroll,A. Chester, C. J. Chiara, K. Childers, B. R. Clark, B. P. Crider, J. T. Harke, B. Longfellow, R. S. Lubna, S. Luitel, T. H. Ogunbeku,
A. L. Richard, S. Saha, N. Shimizu, O. A. Shehu, Y. Utsuno, R. Unz, Y. Xiao, S. Yoshida, and Y. Zhu, “β− decay of exotic P and S
isotopes with neutron number near 28,” Phys. Rev. C 106, 064314 (2022).
A. Revel, J. Wu, H. Iwasaki, J. Ash, D. Bazin, B. A. Brown, J. Chen, R. Elder, P. Farris, A. Gade, M. Grinder, N. Kobayashi, J. Li,
B. Longfellow, T. Mijatovic, J. Pereira, A. Poves, A. Sanchez, N. Shimizu, M. Spieker, Y. Utsuno, and D. Weisshaar, “Large collectivity
in 29 Ne at the boundary of the island of inversion,” Phys. Lett. B 838, 137704 (2023).
J. A. Lay, A. Vitturi, L. Fortunato, Y. Tsunoda, T. Togashi, and T. Otsuka, “Two-particle transfer processes as a signature of shape phasetransition in Zirconium isotopes,” Phys. Lett. B 838, 137719 (2023).
H. F. Li, S. Naimi, T. M. Sprouse, M. R. Mumpower, Y. Abe, Y. Yamaguchi, D. Nagae, F. Suzaki, M. Wakasugi, H. Arakawa, W. B. Dou,
D. Hamakawa, S. Hosoi, Y. Inada, D. Kajiki, T. Kobayashi, M. Sakaue, Y. Yokoda, T. Yamaguchi, R. Kagesawa, D. Kamioka,
T. Moriguchi, M. Mukai, A. Ozawa, S. Ota, N. Kitamura, S. Masuoka, S. Michimasa, H. Baba, N. Fukuda, Y. Shimizu, H. Suzuki,
H. Takeda, D. S. Ahn, M. Wang, C. Y. Fu, Q. Wang, S. Suzuki, Z. Ge, Yu.A. Litvinov, G. Lorusso, P. M. Walker, Zs. Podolyak, andT. Uesaka, “First application of mass measurements with the Rare-RI Ring Reveals the solar r-process abundance trend at A = 122 andA = 123,” Phys. Rev. Lett. 128, 152701 (2022).
S. Iimura, M. Rosenbusch, A. Takamine, Y. Tsunoda, M. Wada, S. Chen, D. S. Hou, W. Xian, H. Ishiyama, S. Yan, P. Schury, H. Crawford,
P. Doornenbal, Y. Hirayama, Y. Ito, S. Kimura, T. Koiwai, T. M. Kojima, H. Koura, J. Lee, J. Liu, S. Michimasa, H. Miyatake,J. Y. Moon, S. Naimi, S. Nishimura, T. Niwase, A. Odahara, T. Otsuka, S. Paschalis, M. Petri, N. Shimizu, T. Sonoda, D. Suzuki,
Y. X. Watanabe, K. Wimmer, and H. Wollnik, “Study of the N = 32 and N = 34 shell gap for Ti and V by the ﬁrst high-precisionmultireﬂection time-of-ﬂight mass measurements at BigRIPS-SLOWRI,” Phys. Rev. Lett. 130, 012501 (2023).
T. Nishi, K Itahashi, D. S. Ahn, G. P. A. Berg, M. Dozono, D. Etoh, H. Fujioka, N. Fukuda, N. Fukunishi, H. Geissel, E. Haettner,
T. Hashimoto, R. S. Hayano, S. Hirenzaki, H. Horii, N. Ikeno, N. Inabe, M. Iwasaki, D. Kameda, K. Kisamori, Y. Kiyokawa, T. Kubo,
K. Kusaka, M. Matsushita, and piAF Collaboration, “Chiral symmetry restoration at high matter density observed in pionic atoms,”Nat. Phys. 19, 788 (2023).
M. Rosenbusch, M. Wada, S. Chen, A. Takamine, S. Iimura, D. Hou, W. Xian, S. Yan, P. Schury, Y. Hirayama, Y. Ito, H. Ishiyama,
S. Kimura, T. Kojima, J. Lee, J. Liu, S. Michimasa, H. Miyatake J. Y. Moon M. Mukai S. Naimi S. Nishimura T. Niwase, T. Sonoda,
Y. X. Watanabe, and H. Wollnik “The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN’s RIBF
facility,” Nucl. Instrum. Methods Phys. Res. A 1047, 167824 (2023).
D. Piatti, E. Masha, M. Aliotta, J. Balibrea-Correa, F. Barile, D. Bemmerer, A. Best, A. Boeltzig, C. Broggini, C. G. Bruno, A. Caciolli,
F. Cavanna, T. Chillery, G. F. Ciani, A. Compagnucci, P. Corvisiero, L. Csedreki, T. Davinson, R. Depalo, A. di Leva, Z. Elekes, F. Ferraro, E. M. Fiore, A. Formicola, Zs. Fülp̈, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, G. Imbriani, M. Junker, M. Lugaro,
P. Marigo, R. Menegazzo, V. Mossa, F. R. Pantaleo, V. Paticchio, R. Perrino, P. Prati, D. Rapagnani, L. Schiavulli, J. Skowronski, K. Stöckel, O. Straniero, T. Szücs, M. P. Takács, and S. Zavatarelli, “First direct limit on the 334 keV resonance strength in
22
Ne(α, γ)26 Mg reaction,” Eur. Phys. J. A 58, 194 (2022).
L. Lalanne, O. Sorlin, A. Poves, M. Assié, F. Hammache, S. Koyama, D. Suzuki, F. Flavigny, V. Girard-Alcindor, A. Lemasson, A. Matta,
T. Roger, D. Beaumel, Y. Blumenfeld, B. A. Brown, F. De Oliveira Santos, F. Delaunay, N. de Séréville, S. Franchoo, J. Gibelin, J. Guillot, O. Kamalou, N. Kitamura, V. Lapoux, B. Mauss, P. Morfouace, M. Niikura, J. Pancin, T. Y. Saito, C. Stodel, and J. -C. Thomas,“Structure of 36 Ca under the coulomb magnifying glass,” Phys. Rev. Lett. 129, 122501 (2022).
N. Ozawa, H. Nagahama, and Y. Sakemi, “Francium ion source with novel methods of target heating and beam characterization,” Rev.
Sci. Instrum. 94, 023306 (2023).
K. S. Tanaka, K. Harada, T. Hayamizu, R. Kita, R. Kono, K. Maruta, H. Nagahama, N. Ozawa, Y. Sakemi, and R. Sugimori, “Anaccelerator experiment for junior and senior high school students to improve students’ involvement in fundamental physics,” Phys.
Edu. 57, 045013 (2022).

[Review Articles]

早川勢也, 山口英斉, 梶野敏貴, 「ビッグバン元素合成—『トロイの木馬法』で迫る『リチウム問題』」, 日本物理学会誌 77, 547 (2022).
N. Shimizu, “Recent Progress of Shell-Model Calculations, Monte Carlo Shell Model, and Quasi-Particle Vacua Shell Model,” Physics 4,1081 (2022).
Y. Utsuno, “Probing diﬀerent characteristics of shell evolution driven by central, spin-orbit, and tensor forces,” Physics 4, 185 (2022).

[Proceedings]
X. Yao, M. Kusakabe, T. Kajino, S. Cherubini, Seiya, Hayakawa, amd H. Yamaguchi, “Supernova nucleosynthesis, radioactive nuclear
reactions and neutrino-mass hierarchy,” EPJ Web Conf. 260, 01007 (2022).
H. Yamaguchi, S. Hayakawa, N. R. Ma, H. Shimizu, K. Okawa, L. Yang, D. Kahl, M. La Cognata, L. Lamia, K. Abe, O. Beliuskina,
S. M. Cha, K. Y. Chae, S. Cherubini, P. Figuera, Z. Ge, M. Gulino, J. Hu, A. Inoue, N. Iwasa, A. Kim, D. Kim, G. Kiss, S. Kubono,- 388 -

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M. La Commara, M. Lattuada, E. J. Lee, J. Y. Moon, S. Palmerini, C. Parascandolo, S. Y. Park, V. H. Phong, D. Pierroutsakou,
R. G. Pizzone, G. G. Rapisarda, S. Romano, C. Spitaleri, X. D. Tang, O. Trippella, A. Tumino, N. T. Zhang, Y. H. Lam, A. Heger,
A. M. Jacobs, S. W. Xu, S. B. Ma, L. H. Ru, E. Q. Liu, T. Liu, C. B. Hamill, A. St J. Murphy, J. Su, X. Fang, M. S. Kwag, N. N. Duy,
N. K. Uyen, D. H. Kim, J. Liang, A. Psaltis, M. Sferrazza, Z. Johnston, and Y. Y. Li, “Experimental studies on astrophysical reactions
at the low-energy RI beam separator CRIB,” EPJ Web Conf. 260, 03003 (2022).
J. Hu, H. Yamaguchi, Y. H. Lam, A. Heger, D. Kahl, A. M. Jacobs, Z. Johnston, S. W. Xu, N. T. Zhang, S. B. Ma, L. H. Ru, E. Q. Liu,
T. Liu, S. Hayakawa, L. Yang, H. Shimizu, C. B. Hamill, A. St J. Murphy, J. Su, X. Fang, K. Y. Chae, M. S. Kwag, S. M. Cha,
Duy, N. N., Uyen, N. K., Kim, D. H., R. G. Pizzone, M. La Cognata, S. Cherubini, S. Romano, A. Tumino, J. Liang, A. Psaltis,
M. Sferrazza, D. Kim, Y. Y. Li, and S. Kubono, “First measurement of 25 Al + p resonant scattering relevant to the astrophysicalreaction 22 Mg(α, p)25 Al,” EPJ Web Conf. 260, 05001 (2022).
M. L. Sergi, L. Lamia, G. G. Rapisarda, M. Mazzocco, S. Cherubini, G. D’Agata, A. Di Pietro, J. P. Fernandez-Garcia, P. Figuera,
M. Fisichella, G. L. Guardo, M. Gulino, S. Hayakawa, M. La Cognata, M. Lattuada, A. A. Oliva, S. Palmerini, R. G. Pizzone,
S. M. R. Puglia, S. Romano, R. Spartà, C. Spitaleri, D. Torresi, and A. Tumino, “Trojan Horse Method for n-induced reaction investigations at astrophysical energies,” in Particles and Nuclei International Conference 2021 (PANIC2021), Proc. Science, 380, 342(2022).
H. Yamaguchi, S. Hayakawa, N. R. Ma, H. Shimizu, K. Okawa, Q. Zhang, L. Yang, D. Kahl, M. La Cognata, L. Lamia, K. Abe,O. Beliuskina, S. M. Cha, K. Y. Chae, S. Cherubini, P. Figuera, Z. Ge, M. Gulino, J. Hu, A. Inoue, N. Iwasa, A. Kim, D. Kim,
G. Kiss, S. Kubono, M. La Commara, M. Lattuada, E. J. Lee, J. Y. Moon, S. Palmerini, C. Parascandolo, S. Y. Park, V. H. Phong,
D. Pierroutsakou, R. G. Pizzone, G. G. Rapisarda, S. Romano, C. Spitaleri, X. D. Tang, O. Trippella, A. Tumino, N. T. Zhang,
Y. H. Lam, A. Heger, A. M. Jacobs, S. W. Xu, S. B. Ma, L. H. Ru, E. Q. Liu, T. Liu, C. B. Hamill, A. St J. Murphy, J. Su, X. Fang,
M. S. Kwag, N. N. Duy, N. K. Uyen, D. H. Kim, J. Liang, A. Psaltis, M. Sferrazza, Z. Johnston, and Y. Y. Li, “RIB induced reactions:
Studying astrophysical reactions with low-energy RI beam at CRIB,” EPJ Web Conf. 275, 01015 (2023).
K. Okawa, M. Kim, K. Chae, S. Hayakawa, S. Adachi, S. Cha, T. W. Chillery, T. Furuno, G. Gu, S. Hanai, N. Imai, D. Kahl, T. Kawabata, C. Kim, D. Kim, S. Kim, S. Kubono, M. Kwag, J. Li, N. Ma, Shin´ichiro Michimasa, U. N. Kim, D. N. Ngoc, K. Sakanashi,
H. Shimizu, O. Sirbu, H. Yamaguchi, R. Yokoyama, and Q. Zhang, “Direct measurement of the 26 Si(α, p)29 P reaction at CRIB for the
nucleosynthesis in the X-ray bursts,” EPJ Web Conf. 275, 02009 (2023).
H. Murakami for the ALICE Collaboration, “Thermal radiation and direct photon production measurements with dielectrons in Pb–Pb
and pp collisions,” Strangeness in Quark Matter (SQM 2022), June 13–17, 2022, Busan, Korea, EPJ Web Conf. 276, 06011 (2023).
D. Sekihata for the ALICE Collaboration, “Thermal radiation and direct photon production in Pb–Pb and pp collisions with dielectronsin ALICE,“ International Conference on High Energy Physics, Bolognia, Italy, July 6–13, 2022, PoS(ICHEP2022)452.
Shutaro Hanai, Shinsuke Ota, Reiko Kojima, Masanori Dozono, Nobuaki. Imai, Shin’ichiro Michimasa, Susumu Shimoura, Juzo Zenihiro,
Kento Inaba, and Yuto Hijikata “Development of fast-response tracking detector for high-intensity ion beams,,” Radiation Detectors
and Their Uses Proceedings of the 36th Workshop on Radiation Detectors and Their Uses in KEK, 2023, pp. 24–34.
S. Motoki, Y. Kazeki, N. Hiroki, O. Naoya, N. Shintaro, N. Teruhito, U. Daisuke, F. Mirai, N. Keisuke, H. Tomohiro, H. Hiromitsu,
S. Yasuhiro, and M. Yasuyuki, “Development of neutralization apparatus and francium source for the francium electric dipole moment
search,” JPS Conf. Proc. 37, 20605 (2022).
K. Nakamura, S .Nagase, T. Nakashita, T. Hayamizu, T. Aoki, H. Nagahama, N. Ozawa, M. Sato, K. Yamane, M. Fukase, D. Uehara,
A. Takamine, and Y. Sakemi, “Development of a laser frequency stabilization and an optical transmission system for the francium
electric dipole moment search,” J. Phys. Conf. Ser. 2249, 012010 (2022).

Presentations[International Conferences/Workshops]
H. Yamaguchi (invited), “RIB induced reactions: Studying astrophysical reactions with low-energy RI beam at CRIB,” The 11th European
Summer School on Experimental Nuclear Astrophysics (Santa Tecla School, ESSENA 2022), INFN-LNS, Catania, Italy, June 12–19,
2022.
H. Yamaguchi (invited), “New evaluation of 22 Mg(α, p) reaction rate and X-ray burst light curve,” UKAKUREN-RCNP Conference on
AstroNuclear Physics (ANP2022), Osaka University, Toyonaka, Osaka, Japan, July 20–21, 2022.
H. Yamaguchi (invited), “Big-Bang Li problem and nuclear reactions,” International Workshop “Origin of Elements and Cosmic Evolution: From Big-Bang to Supernovae and Mergers” (OECE2022), Beihang University, Beijing, China, July 20–22, 2022.
S. Hayakawa (invited), “New measurement of the 7 Be + n reactions and its impact on the primordial 7 Li abundance,” The 16th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG16), Hanoi, Vietnam, October 24–28, 2022.
H. Yamaguchi (invited), “Studies on RI-involving astrophysical reactions at CRIB,” ECT* Workshop “Key Reactions in Nuclear Astrophysics,” ECT*, Trento, Italy, December 12–16, 2022.
H. Yamaguchi (oral), 「X 線バーストにおける重要不安定核反応の実験的検証/Experimental investigation of relevant unstable-nucleus
reactions in X-ray bursts」, RIBF ULIC Mini Workshop-39 星の進化と爆発天体における核反応の物理 (Physics of nuclear reactions
in stellar evolution and explosive stellar objects), Wako, Saitama, Japan (RIKEN), February 20–21, 2023.
K. Okawa (poster), “Direct measurement of the 26 Si(α, p)29 P reaction for the nucleosynthesis in the X-ray bursts,” FoPM International
Symposium, Hongo Campus (Ito International Research Center), February 6–8, 2023.
S. Hayakawa (oral), “Nuclear astrophysics at the low-energy RI beam separator CRIB,” RIBF Users Meeting 2022, Web meeting hosted
by RIKEN, Wako, Saitama, Japan, September 7–9, 2022.
T. Gunji (invited) for the ALICE Collaboration, “Recent results from the ALICE experiment at the LHC and its future prospects,” The
15th Asia Paciﬁc Physics Conference (APPC15), Online, August 21–26, 2022.

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T. Gunji (invited), “Hunting for dark photons,” GSI EMMI RRTF, Real and Virtual photon production at ultra-low transverse momentum
and low mass at LHC, GSI, August 1–8, 2022.
T. Gunji (invited), “High-energy nuclear physics in Japan and view on EIC,” EIC Asia Workshop, RIKEN, March 16–18, 2023.
H. Murakami for the ALICE Collaboration, “Thermal radiation and direct photon production in Pb–Pb and pp collisions with dielectrons,”
Strangeness in Quark Matter (SQM 2022), Busan, Korea & Online, June 13–17, 2022.
D. Sekihata for the ALICE Collaboration, “Thermal radiation and direct photon production in Pb–Pb and pp collisions with dielectronsin ALICE,” International Conference on High Energy Physics, Bolognia, Italy, July 6–13, 2022.
Y. Utsuno (invited), “Recent ﬁndings about shell evolution in the neutron-rich Ca region,” RIKEN Workshop on Physics of RI: Recent
Progress and Perspectives, Wako, Japan, May 30–June 1, 2022.
Y. Utsuno (invited), “Large-scale shell-model calculations: from low-lying spectra to compound states,” A3F-CNS Summer School 2022,
Kumagaya, Japan, August 20–24, 2022.
Y. Utsuno (invited), “Overview of shell-model results for the 3rd SEASTAR campaign,” REIMEI Workshop on Unveiling nuclear shells
and correlations in exotic nuclei through knockout reactions, Darmstadt, Germany, October 10–12, 2022.
K. Yanase (oral), “Theoretical uncertainty on the nuclear Schiﬀ moments of 129 Xe and 199 Hg,” The 14th International Workshop on
Fundamental Physics Using Atoms (FPUA2022), Fukuoka, Japan, November 24–25, 2022.
Y. Utsuno (invited), N. Shimizu, and Y. Tsunoda, “Large-scale shell-model approach to nuclear collective motion,” 66th DAE Symposium
on Nuclear Physics, Guwahati, India, December 1–5, 2022.
K. Yanase (invited), “Shell-model study for the Nuclear Schiﬀ moments of 129 Xe and 199 Hg,” KMI workshop: Searches for Electric Dipole
Moments: From Theory to Experiment, Nagoya, Japan, March 2–4, 2023.
Y. Utsuno (invited), “The nuclear shell model,” INTPART School 2023, Onna, Japan, February 20–March 7, 2023.
S. Michimasa (invited) “Direct mass measurements around neutron-rich Ca region at SHARAQ,” Physics of RI: Recent progress andperspectives RIKEN Nishina Cener, Saitama, Japan, May 30–June 1, 2022.
S. Michimasa (invited) “Present Status of OEDO/FY2020–2022” OEDO/SHARAQ collaboration meeting 2022, Web meeting hosted by
CNS, Wako, Saitama, Japan, August 30, 2022.
N. Imai (invited) “SHARAQ18” OEDO/SHARAQ collaboration meeting 2022, Web meeting hosted by CNS, Wako, Saitama, Japan,
August 30, 2022.
S. Hanai (invited) “SHARAQ13” OEDO/SHARAQ collaboration meeting 2022, Web meeting hosted by CNS, Wako, Saitama, Japan,
August 30, 2022.
S. Michimasa (invited) “OEDO-SHARAQ system: multifaceted performances in low-energy RI production and high-resolution spectroscopy,” The 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS XIX), RISP/IBS,
Daejeon, Korea, October 3–7, 2022.
S. Michimasa (invited) “Mass measurements of exotic nuclei at OEDO-SHARAQ,” The International Symposium on Nuclear Spectroscopy for Extreme Quantum Systems (NUSPEQ2023), Numazu, Sizuoka, Japan, March 7–9, 2023.
T. Chillery (poster) “Treating Radioactive Waste: Measurement of 93 Zr + d Reactions at 30 MeV/nucleon,” The International Symposium
on Nuclear Spectroscopy for Extreme Quantum Systems (NUSPEQ2023), Numazu, Sizuoka, Japan, March 7–9, 2023.
N. Kitamura (poster) “In-beam γ-ray spectroscopy of 32 Mg” The International Symposium on Nuclear Spectroscopy for Extreme Quantum
Systems (NUSPEQ2023), Numazu, Sizuoka, Japan, March 7–9, 2023.
R. Yokoyama (poster) “New implantation detectors for decay spectroscopy at fragmentation facilities” The International Symposium on
Nuclear Spectroscopy for Extreme Quantum Systems (NUSPEQ2023), Numazu, Sizuoka, Japan, March 7–9, 2023.
S. Hanai (poster) “Direct mass measurement of neutron-deﬁcient Fe isotopes” The International Symposium on Nuclear Spectroscopy for
Extreme Quantum Systems (NUSPEQ2023), Numazu, Sizuoka, Japan, March 7–9, 2023.
J. Li (poster) “Study of heavy-ion fusion reactions in inverse kinematic systems using low-energy 136 Xe beam,” The International Symposium on Nuclear Spectroscopy for Extreme Quantum Systems, Numazu, Sizuoka, Japan, March 7–9, 2023.
S. Hanai (invited) “Direct measurement of the masses of Fe isotopes around the proton dripline,” RIBF users meeting, Web meeting
hosted by RIKEN Nishina Center, Wako, Saitama, Japan, September 22, 2022.
T. Chillery (invited) “Recent Studies on Heavy-Isotope Nucleosynthesis Using (d,p) Transfer Reactions at OEDO-SHARAQ,” RIBF users
meeting, Web meeting hosted by RIKEN Nishina Center, Wako, Saitama, Japan, September 22, 2022.
J. T. Li (oral), “Study of the fusion reaction in inverse kinematics with the low-energy 136 Xe beams,” UT-Tsinghua University Joint mini
workshop, Tsinghua University, Beijing, China, March 13, 2023.
S. Hanai (poster), “Development of a fast response PPAC for high-intensity heavy-ion beams,” The 19th International Conference on
Electromagnetic Isotope Separators and Related Topics (EMIS XIX), Daejeon, Korea (RISP/IBS), October 3–7, 2022.
K. Yako (oral), “Double and single charge exchange reactions on 48 Ca by 12 C beam at 250 A MeV,” YKIS2022b, Kyoto, May 23–27,
2022.
A. Sakaue (poster), “The Search for double Gamow-Teller giant resonance at RIBF BigRIPS,” Annual meeting of A3 Foresight Program,
Nuclear Physics in the 21st century, Osaka, February 13–15, 2023.
A. Sakaue (poster), “The search for double Gamow-Teller giant resonance with the (12 C,12 Be(0+2 )) reaction,” NUSPEQ2023, Numazu,March 7–9, 2023.
K. Kawata (poster), “The production of high-spin isomers around 52 Fe in fragmentation reaction of 58 Ni and 59 Co beams at
350 MeV/nucleon,” NUSPEQ2023, Numazu, March 7–9, 2023.
K. Nakamura (oral), “400-m-Long Polarization-Maintaining Fibers for Magneto-Optical Trapping of francium Atoms,” The 15th Paciﬁc- 390 -

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Rim Conference on Lasers and Electro-Optics (CLEO-PR 2022), Online, August 2, 2022.
H. Nagahama (invited), “Searching for the permanent electric dipole moment using laser cooled francium atoms,” 6th Workshop on the
Physics of fundamental Symmetries and Interactions at low energies and the precision frontier (PSI2022), Switzerland (Paul Scherrer
Institute), October 19, 2022.
M. Fukase (invited), “Search for permanent EDM by using Fr atoms,” 14th International Workshop on Fundamental Physics Using Atoms(FPUA2022), Fukuoka, Japan (Kyushu University), November 24, 2022.

[Domestic Conferences/Workshops]

鎌倉恵太 (ポスター発表),「14 GHz Hyper ECR イオン源を用いた ECR プラズマの研究」, 第 19 回日本加速器学会年会, オンライ
ン, 2022 年 10 月 18–21 日.
大川皓大 (口頭発表), 「X 線バースト中の元素合成における 26 Si(α, p)29 P 反応の直接測定」, 日本物理学会 2022 年秋季大会, 岡山
理科大学, 2022 年 9 月 6–8 日.
S. Hayakawa (oral), “Activity report of CRIB,” RIBF Users Meeting 2022, Session 3, オンライン, 2022 年 9 月.
早川勢也 (口頭発表), “Measurement of the 7 Be + n reactions by Trojan Horse method updating primordial 7 Li abundance,” 宇宙核物理の展開 UKAKUREN-RCNP Conference on AstroNuclear Physics (ANP2022), 大阪大学 & オンライン, 2022 年 7 月.
山口英斉 (口頭発表), 「軽い原子核の直鎖クラスター状態の実験的検証」, シンポジウム「原子核クラスター物理の新たな進展と展望」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 25 日.
√
H. Murakami for the ALICE Collaboration, “Direct photon production in proton-proton collisions at s = 13 TeV via interanl conversion
technique with ALICE,” 日本物理学会 2022 年秋季大会, 岡山理科大学, 2022 年 9 月 6–8 日.
関畑大貴, 「電磁・ソフトプローブを通した QGP 物理の結果と展望」, 日本物理学会 2023 春季大会, 実験核物理・理論核物理領域
合同シンポジウム: 次世代の高エネルギー原子核衝突: 何が理解され, 何を理解すべきか？, オンライン, 2023 年 3 月 22 日.
馬場仁志 for the ALICE Collaboration, 「機械学習を用いた, ALICE-TPC 検出器における空間電荷効果の補正」, 日本物理学会 2022
年秋季大会, 岡山理科大学, 2022 年 9 月 6–8 日.
T. Gunji (招待講演), “Future Prospects of Quark Cluster Physics using ultra-relativistic heavy-ions,” 第 8 回クラスター階層領域研究会, 大阪大学吹田キャンパス接合科学研究所, 2023 年 2 月 9–11 日.
T. Gunji (招待講演), 「LHC-ALICE 実験の新しいデータ収集系」, RCNP 研究会「原子核実験の次世代データ収集システム基盤開発にむけて」, 大阪大学吹田キャンパス, 2022 年 5 月 16–17 日.
T. Gunji (invited), 「WG4（オンラインフィルタリング・演算加速器）報告と展望」, 原子核実験の先端データ収集システム—標準化と将来—, 2023 年 3 月 17 日.
T. Gunji (invited), 「ALICE 実験における Vertex Trackers」, シリコンプラットフォーム研究会, KEK, 2022 年 8 月 9 日.
宇都野穣 (招待講演), 「大規模殻模型計算—現実的な原子核構造を得るには」, 研究会「宇宙核物理の展開」, 豊中市 (大阪大学), 2022
年 7 月 19–21 日.
宇都野穣 (口頭発表), 清水則孝, 井手口栄治, 青井考, 「大規模殻模型計算と 3 準位模型による 40 Ca の超変形状態からの E0 遷移の理解」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学), 2022 年 9 月 6–8 日.
柳瀬宏太 (招待講演), 「原子核殻模型によるキセノン原子核の核行列要素の理論計算」, 二重ベータ崩壊核行列要素実験理論合同研究会, 吹田市 (大阪大学核物理研究センター), 2022 年 10 月 3–4 日.
柳瀬宏太 (口頭発表), 清水則孝, 角田佑介, 宇都野穣, 「モンテカルロ殻模型による N = 82 付近のベータ崩壊半減期の理論計算」,
日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
N. Kitamura (招待講演), 「高性能波形ディジタイザの需要調査と今後の開発方針」, 原子核実験の先端データ収集システム—標準化と将来—, 大阪大学核物理研究センター, 2023 年 3 月 17 日.
R. Yokoyama (招待講演), 「原子核の複数粒子放出過程」, 第四回若手放談会, エキゾチック核物理の未来, 理研神戸・融合連携イノ
ベーション推進棟, 2023 年 3 月 15–17 日.
R. Yokoyama (招待講演), 「核破砕・分裂反応式不安定核生成施設における β 核分光のためのシンチレーション検出器」, Scintillator
for Medical, Astroparticle and Environmental Radiation Technologies, Tokushima University, December 17–19, 2022.
N. Imai (invited), “Study of the neutron capture rate on the unstable nuclei via the surrogate reactions,” Workshop for the nucleosynthesisin the universe from the neutron capture, Tokyo, Japan (University of Tokyo), February 9–10, 2023.
T. Chillery (oral), “Measurement of 130 Sn(d,p) Reaction for Neutron-Capture Rate in r-process Nucleosynthesis,” JPS Autumn 2022
meeting, Okayama, September 6–8, 2022.
阪上朱音 (口頭発表),「(12 C,12 Be(0+2 )) 反応を用いた二重ガモフ・テラー巨大共鳴状態の探索」, 日本物理学会 2022 年秋季大会, 岡
山理科大学, 2022 年 9 月 6–8 日.

[Seminars]

S. Hayakawa, C2R2 Seminar “Direct and indirect methods at CRIB for nuclear astrophysical reactions,” Online, Organized by CENS,IBS, June 2022.
Y. Utsuno, “Unveiling exotic nuclear structure far from stability,” Colloquium at Saha Institute of Nuclear Physics, Kolkota, India,
December 7, 2022.
N. Imai, “OEDO beam line at RIBF and Its physics program,” Beigjing China (Tsinghua University), March 13, 2023.
N. Imai, “The decelerating and focusing device OEDO in RIBF and the nuclear astrophysics program with the surrogate nuclear reaction,”
Beijing, China (Chinese Institute of Atomic Energy), March 13, 2023.
N. Imai, “OEDO, the deceleration and focusing element at RIBF, and the physics program using OEDO,” Lanzhou, China (Institute ofModern Physics), March 16, 2023.

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AwardsS. Hanai, ANPha Award in The International Symposium on Nuclear Spectroscopy for Extreme Quantum Systems (NUSPEQ2023),
Numazu, Sizuoka, Japan, March 7–9, 2023.
A. Sakaue, Poster award for young scientists, Annual meeting of A3 Foresight Program, Nuclear Physics in the 21st century, Osaka,February 13–15, 2023.

Outreach Activity
N. Imai “Beyond the nano scale: a femto world consisting of protons and neutrons,” Open campus of the School of Sience, the Universityof Tokyo, Tokyo, Japan, August 4, 2022.

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RIKEN Accel. Prog. Rep. 56 (2023)

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 nuclides. WNSC operates the KEK Isotope Separation System (KISS),an electromagnetic isotope separator featuring elemental selectivity from resonance laser ionization in a gas catcher. The KISS facility
uniquely provides various neutron-rich isotopes of refractory elements via multinucleon transfer reactions to users from universities.
Its provision of nuclei in the vicinity of the neutron magic number N = 126 and N = 152. Optical and β-γ spectroscopy andmass spectrometry have been applied to these neutron-rich nuclear beams for nuclear structure and nuclear astrophysical studies.
The WNSC leads comprehensive mass measurements of all-available nuclides at RIBF using multi-reﬂection time of ﬂight mass
spectrographs (MRTOF-MS). Three MRTOF setups were placed at the GARIS-II, the beam dump of the ZeroDegree spectrometer,
and the KISS—the masses of more ore than 400 nuclides, including dozens of ﬁrst masses. A new uranium isotope, 241 U, wasdiscovered at KISS-MRTOF by means of precise mass measurement. An upgrade plan, KISS- II, is being considered a future projectof WNSC aiming at the study of the origin of uranium for the ﬁrst time.

2. Major Research Subjects
(1)
(2)
(3)
(4)
(5)
(6)

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
Development of KISS-II

3. Summary of Research Activity

The Wako Nuclear Science Center (WNSC) provides low-energy short-lived radioactive ion beams of neutron-rich refractoryelements to university researchers using the KEK isotope separator system (KISS). In FY2021, ﬁve experiments were executed. Dueto the restrictions of COVID-19, only a limited number of foreign collaborators participated in the experiments. Laser spectroscopyof neutron-rich refractory elements, including long-lived isotopes, is uniquely performed using the resonant laser ionization schemeof KISS and the capability of isobaric separation of the MRTOF device.
The team of WNSC leads comprehensive mass measurements of all available nuclides at RIKEN RIBF using multiple MRTOF
mass spectrographs. Newly installed beta-ToF detectors to the GARIS-II MRTOF and the ZeroDegree MRTOF setups eliminate
background events and allow for the determination of the lifetime of short-lived nuclides.
The WNSC announced two press releases; one is for discovering a new uranium isotope, 241 U, the ﬁrst neutron-rich new uranium
isotope in the last 40 years. The other is for the disappearance of a neutron magic number, N = 34, for titanium and vanadium isotopes.
The WNSC plans to extend the present KISS facility to investigate the nuclides in the neutron-rich actinides using the multinucleon transfer reactions of actinide targets to study the origin of uranium. Some pilot developments are in progress, particularly fora large He gas catcher with a radiofrequency wire curtain device.

Members
Group Leader
Michiharu WADA
Researchers
Yutaka WATANABEPeter SCHURY
Sunchan JEONG
Yoshikazu HIRAYAMA

Hiroari MIYATAKE
Marco ROSENBUSH
Toshitaka NIWASE
Taiki TANAKA

Visiting Researchers
Hermann WOLLNIK (NMSU)
Andrei ANDREYEV (University of York)

Hiroshi WATANABE (Beihan University)
Dongsheng HOU (IMP)Assistant
Machiko IZAWA- 393 -

Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

List of Publications & Presentations
Publications[Original Papers]
T. Niwase, W. Xian, M. Wada, M. Rosenbusch, S. Chen, A. Takamine, J. Liu, S. Iimura, D. Hou, S. Yan, H. Ishiyama, H. Miyatake,S. Nishimura, D. Kaji, K. Morimoto, Y. Hirayama, Y. X. Watanabe, S. Kimura, P. Schury, and H. Wollnik, “Development of a β-TOF
detector: An enhancement of the α-TOF detector for use with β-decaying nuclides,” Prog. Theor. Exp. Phys. 2023, 031H01 (2023).
T. Niwase, Y. X. Watanabe, Y. Hirayama, M. Mukai, P. Schury, A. N. Andreyev, T. Hashimoto, S. Iimura, H. Ishiyama, Y. Ito, S. C. Jeong,
D. Kaji, S. Kimura, H. Miyatake, K. Morimoto, J. -Y. Moon, M. Oyaizu, M. Rosenbusch, A. Taniguchi, and M. Wada, “Discovery of
new isotope 241 U and systematic high-precision atomic mass measurements of neutron-rich Pa-Pu nuclei produced via multinucleon
transfer reactions,” Phys. Rev. Lett. 130, 132502-1–6 (2023).
T. Niwase, P. Schury, M. Wada, and SHE-Mass Collaborators, “Accurate event assignment from the decay-correlated mass measurementof the superheavy nuclide 257 Db,” J. Nucl. Radiochem. Sci. 23, 1–4 (2023).
M. Rosenbusch, M. Wada, S. Chen, A. Takamine, S. Iimura, D. Hou, W. Xian, S. Yan, P. Schury, Y. Hirayama, Y. Ito, H. Ishiyama,
S. Kimura, T. Kojima, J. Lee, J. Liu, S. Michimasa, H. Miyatake, M. Mukai, J. Y. Moon, S. Nishimura, S. Naimi, T. Niwase, T. Sonoda,
Y. X. Watanabe, and H. Wollnik, “The new MRTOF mass spectrograph following the ZeroDegree spectrometer at RIKEN’s RIBF
facility,” Nucl. Instrum. Methods Phys. Res. A 1047, 167824 (2023).
S. Iimura, M. Rosenbusch, A. Takamine, Y. Tsunoda, M. Wada, S. Chen, D. S. Hou, W. Xian, H. Ishiyama, S. Yan, P. Schury, H. Crawford,
P. Doornenbal, Y. Hirayama, Y. Ito, S. Kimura, T. Koiwai, T. M. Kojima, H. Koura, J. Lee, J. Liu, S. Michimasa, H. Miyatake,J. Y. Moon, S. Naimi, S. Nishimura, T. Niwase, A. Odahara, T. Otsuka, S. Paschalis, M. Petri, N. Shimizu, T. Sonoda, D. Suzuki,
Y. X. Watanabe, K. Wimmer, and H. Wollnik, “Study of the N = 32 and N = 34 shell gap for Ti and V by the ﬁrst high-precisionmultireﬂection time-of-ﬂight mass measurements at BigRIPS-SLOWRI,” Phys. Rev. Lett. 130, 012501-1–6 (2023).
Y. Hirayama, M. Mukai, Y. X. Watanabe, P. Schury, H. Nakada, J. Y. Moon, T. Hashimoto, S. Iimura, S. C. Jeong, M. Rosenbusch,
M. Oyaizu, T. Niwase, M. Tajima, A. Taniguchi, M. Wada, and H. Miyatake, “In-gas-cell laser resonance ionization spectroscopy of200, 201
Pt,” Phys. Rev. C 106, 034326-1–11 (2022).
T. Aoki, Y. Hirayama, H. Ishiyama, S. C. Jeong, S. Kimura, Y. Makida, H. Miyatake, M. Mukai, S. Nishimura, K. Nishio, T. Niwase,
T. Ogawa, H. Okuno, M. Rosenbusch, P. Schury, Y. Watanabe, and M. Wada, “Design report of the KISS-II facility for exploring theorigin of uranium,” arXiv:2209.12649.

[Review Article]

和田道治, 「超重元素同位体の精密質量測定」, Isotope News 10 月号 (No.783), 6–10 (2022).

Presentations[International Conferences/Workshops]
Y. Watanabe (invited), “Spectroscopy of neutron-rich nuclei produced in multinucleon transfer reactions at KISS,” Physics with SPIRAL2
Heavy Ion Beams, Caen, France, December 12–16, 2022.
Y. Watanabe (oral), “Experimental studies of neutron-rich nuclei around N = 126 and beyond at KEK isotope separation system,” 16th
International Symposium on Origin of Matter and Evolution of Galaxies (OMEG16), Ha Noi, Viet Nam, October 25–28, 2022.
M. Wada (invited), “Comprehensive mass measurements of short-lived nuclides,” 16th International Symposium on Origin of Matter and
Evolution of Galaxies (OMEG16), Ha Noi, Viet Nam, October 25–28, 2022.
T. Niwase (poster), “Technique of decay correlated mass measurement via multi-reﬂection time-of-ﬂight mass spectrograph with an α/βTOF detector,” 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS), Daejeon, Korea,
October 3–7, 2022.
M. Rosenbusch (poster), “High-precision MRTOF mass measurements of radioactive isotopes at RIKEN’s RIBF facility: Recent projects
for ion selection, wideband mass accuracy, and mirror potentials,” 19th International Conference on Electromagnetic Isotope Separators
and Related Topics (EMIS), Daejeon, Korea, October 3–7, 2022.
P. Schury (invited), “Multi-reﬂection time-of-ﬂight mass spectroscopy of superheavy nuclides,” 19th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS), Daejeon, Korea, October 3–7, 2022.
M. Rosenbusch (oral), “Exploring exotic nuclei by high-precision MRTOF mass measurements: The new ion catcher and mass spectrograph at RIKEN’s RIBF factory,” Trapped Charged Particles Conference 2022 (TCP 2022), Glashütten, Germany, September 25–30,
2022.

[Domestic Conferences/Workshops]

向井もも (口頭発表), 「安定イリジウム同位体周辺核の直接質量測定」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月
22–25 日.
M. Rosenbusch (口頭発表), “Recent atomic mass measurements of radioactive species using the new ZD-MRTOF system at BigRIPS/RIKEN,” 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
庭瀬暁隆 (口頭発表), 「超重核の直接質量測定」, 日本物理学会 2023 年春季大会, オンライン, 2023 年 3 月 22–25 日.
庭瀬暁隆 (口頭発表), 「超重・超アクチノイド核の精密質量測定」, 2022 重元素化学研究会, あわら市, 2023 年 3 月 20–21 日.
Y. Watanabe (invited), 「中性子過剰アクチノイド実験への展望」, RIBF ULIC ミニワークショップ「理論と実験で拓く中性子過剰
核の核分裂」, Wako, Japan, February 16–17, 2023.

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Ⅵ. ORGANIZATION AND ACTIVITIES OF RNC

RIKEN Accel. Prog. Rep. 56 (2023)

平山賀一 (招待講演), 「KISS での核分光研究」, 中世捕獲反応で迫る宇宙の元素合成, 文京区 (東京大学), 2023 年 2 月 9–10 日.
渡邊裕 (口頭発表), 「KISS での核分光研究」, 令和 4 年度専門研究会「短寿命 RI を用いた核分光と核物性研究 IX」, オンライン,2023 年 1 月 11 日.
M. Rosenbusch (oral), “New nuclear masses, recent and present developments, and future opportunities of the MRTOF-MS at the ZeroDegree spectrometer,” RIBF Users Meeting, Online, September 20–22, 2022.
Y. Watanabe (oral), “Present status and future plan of KISS,” RIBF Users Meeting, Online, September 20–22, 2022.
T. Niwase (oral), “First direct mass measurement of superheavy nuclide via MRTOF-MS equipped with α-TOF detector,” RIBF Users
Meeting, Online, September 20–22, 2022.
庭瀬暁隆 (招待講演), 「精密質量と崩壊事象の相関測定法の開拓による超重元素の直接質量測定」, 日本放射化学会第 66 回討論会
(2022), 文京区 (東京大学), 2022 年 9 月 16 日.
庭瀬暁隆 (口頭発表), 「精密質量測定による新同位体 241 U の発見」
, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学) & オンライン, 2022 年 9 月 6–9 日.
平山賀一 (口頭発表), 「KISS での低温ヘリウムガスセル開発」, 日本物理学会 2022 年秋季大会, 岡山市 (岡山理科大学) & オンライ
ン, 2022 年 9 月 6–9 日.
M. Rosenbusch (invited), “High-precision mass measurements for astrophysics and nuclear structure studies using the new ZD-MRTOF
system,” 宇核連-RCNP 研究会「宇宙核物理の展開」, UKAKUREN-RCNP Conference on AstroNuclear Physics (ANP2022), Toyonaka,
Japan & Online, July 20–21, 2022.
Y. Watanabe (oral), “Production of neutron-rich nuclei around N = 126 and beyond using multinucleon transfer reactions at KISS project,”
Physics of RI: Recent progress and perspectives, Wako, Japan & Online, May 30–June 1, 2022.

[Seminars]
M. Rosenbusch, “A ﬁrst review of the SLOWRI-MRTOF mass spectrograph following the ZeroDegree spectrometer at BigRIPS,” The
315th RIKEN RIBF Nuclear Physics Seminar, Wako, Japan, February 14, 2023.
M. Wada, “Study of the origins of heavy elements via comprehensive mass measurements of short-lived nuclides/重元素の起源と短寿命
核の質量測定,” 高エネルギー加速器科学セミナー (2022 High Energy Accelerator Science Seminar), Online, June 8, 2022.

Press Releases

チタン・バナジウム中性子過剰同位体で新魔法数の消失を観測〜精密質量測定による原子核構造のより深い理解に期待〜, KEK,
RIKEN, Osaka University, 2023 年 1 月 6 日, https://www.kek.jp/ja/press/202301061400/ .
40 年 ぶ り に 中 性 子 過 剰 な ウ ラ ン 同 位 体 を 新 発 見 〜 ウ ラ ン の 起 源 解 明 に 期 待 〜, KEK, RIKEN, 2023 年 3 月 31 日,
https://www.kek.jp/ja/press/202304010000/ .

Awards

庭瀬暁隆, 「第 17 回（2023 年）日本物理学会実験核物理領域: 若手奨励賞 (Young Scientist Award of the Physical Society of Japan),
第 29 回原子核談話会新人賞」, 2023 年 3 月.
T. Niwase, “RIBF Users Group Thesis Award,” September 2022.
庭瀬暁隆, 「日本放射化学会奨励賞」, 2022 年 9 月.
和田道治, 宮武宇也, 「2021 年度高エネルギー加速器科学研究奨励会西川賞」, 2022 年 5 月.

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VII. APPENDICESⅦ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

List of Symposia & Workshops (April 2022―March 2023)
RNC
1

Physics of RI: Recent progress and perspectives
https://indico2.riken.jp/event/4120/

online, RIBF2F Large
Meeting RoomMay 30–Jun. 1

2

Predictions for sPHENIX
https://www.bnl.gov/sphenix2022

Online, Brookhaven
National Laboratory

July. 20–22

3

RIBF Users Meeting 2021
https://indico2.riken.jp/event/4225/

onlineSep. 20–22

4International workshop on "hadron physics with kaon beam and related topics"
https://kds.kek.jp/event/43204/

onlineOct. 3–4

5

International symposium on clustering as a window on the hierarchical of quantum systems
http://be.nucl.ap.titech.ac.jp/cluster/symposium/334/

online, Sendai
International Center

Oct. 31–
Nov. 3

6

第 5 回「精密武装抗体と機能評価」シンポジウム (Domestic)
https://www.adthree.com/event/2022/07/poster.pdf

onlineDec. 167

第 10 回 RNC 品種改良ユーザー会 (Domestic)
online, Suzuki Umetaro
理研シンポジウム「重イオンビーム育種による持続可能な社会や特産品生産の実現」
Hall
https://www.riken.jp/medialibrary/riken/pr/events/symposia/20230119_1/20230119_1_p.pdf

8

A3 Foresight Annual Meeting 2022
JSPS/NRF/MSFC A3 Foresight Program “Nuclear Physics in the 21st Century”

online, Osaka
International Convention
Center

Feb. 13–15

9

INTPART School 2023
https://sites.google.com/rcnp.osaka-u.ac.jp/intpart23/home

Kafuu Resort Fuchaku
CONDO HOTEL in
Okinawa main island

Feb. 20–
Mar. 3

10

Nuclear Spectroscopy for Extreme Quantum System (NUSPEQ2023)
https://indico2.cns.s.u-tokyo.ac.jp/event/187/overview

Plaza Verde
Convention Complex in
NumazuMar. 7–9

112022 年度ビーム物理研究会・若手の会 (Domestic)
https://indico2.riken.jp/event/4403/

online, RIBF2F Large
Meeting RoomMar. 8–10

12

第４回 RIBF 若手放談会: エキゾチック核物理の将来 (Domestic)
https://indico2.riken.jp/event/3968/

online, Integrated
Innovation Building

Mar. 15–17

13

EIC Asia Workshop
https://indico2.riken.jp/event/4389/

online, Okochi Hall

Mar. 16–18

onlineSep. 1–2

Jan. 19–20

KEK
1

SSRI-PNS Collaboration meeting 2022
https://indico2.riken.jp/event/4202/timetable/?view=standard_inline_minutes- 397 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

List of Seminars (April 2022―March 2023)
Nuclear Physics Monthly Colloquium
Not held in 2022

RIBF Nuclear Physics Seminar
1

Yasuyuki Akiba(RNC)

The Physics at RHIC
https://indico2.riken.jp/event/4118/

May 23

2

Newcomers of RNC in
FY2022

Newcomers Seminarhttps://indico2.riken.jp/event/4145/

Jun. 7

3

Tomoya Naito(RIKEN)

Isospin symmetry breaking in nuclear ground statehttps://indico2.riken.jp/event/4151/

Jun. 224

Meytal Duer(TU Darmstadt)

A four-neutron system probed via alpha knockout reaction from 8He
https://indico2.riken.jp/event/4167/

Jul. 26

5

Wataru Horiuchi(Osaka Metropolitan U.)

What can we learn from nuclear density profiles?
https://indico2.riken.jp/event/4270/

Nov. 7

6

Toshihiko Kawano(Los Alamos National
Laboratory)

Recent advances in compound nuclear reaction theory and its applications
https://indico2.riken.jp/event/4370/

Jan. 137

Gianluca Colò(U. Milan)

A unified framework for nuclear single-particle states and collective vibrations
https://indico2.riken.jp/event/4391/

Jan. 17

8

Takuji Tsujimoto(NAOJ)

Galactic chemical evolution identifying core-collapse supernovae as one of the major
production sites of r-process elements
https://indico2.riken.jp/event/4386/

Jan. 319

Marco Rosenbush(KEK)

A first review of the SLOWRI-MRTOF mass spectrograph following the ZeroDegree
spectrometer at BigRIPS
https://indico2.riken.jp/event/4413/

Feb. 1410

Masayasu Kamimura(RNC)

Recent developments of muon-catalyzed-fusion study and some theoretical predictions
https://indico2.riken.jp/event/4414/

Feb. 28

11

Wen-Chen Chang(Academia Sinica)

Fixed-target charmonium production and pion PDFs
https://indico2.riken.jp/event/4438/

Mar. 20

12Phong Ho Vi(RIKEN)β-delayed one and two neutron emission probabilities and the nuclide abundances aroundthe second r-process peak
https://indico2.riken.jp/event/4445/

Mar. 28

13

Xavier Roca-Maza(U. degli Studi di Milano)

An overview on the nuclear equation of state studied from ground and collective excitedstate properties of nuclei
https://indico2.riken.jp/event/4452/

Apr. 12RIBF ULIC Symposium/mini-WS
1

Sota Yoshida(Utunomiya U.)

The Physics at RHIC
https://indico2.riken.jp/event/4118/

Nov. 292

Mini-Workshop

Newcomers Seminarhttps://indico2.riken.jp/event/4145/

Feb. 16

3

Mini-Workshop

Isospin symmetry breaking in nuclear ground statehttps://indico2.riken.jp/event/4151/

Feb. 20- 398 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

Seminar by Each Laboratory
Nuclear Spectroscopy Laboratory
1

Hiroki Yoneda(RIKEN)

Observations of the MeV gamma-ray universe with Compton telescopes (virtual)
https://indico2.riken.jp/event/4105/

Apr. 27

2

Kuma Susumu(RIKEN)

Microscopic superfluidity in quantum nanodroplets (virtual)
https://indico2.riken.jp/event/4138/

May 27

3

Tomonori Fukuchi(RIKEN)

Measurements of the gamma-ray linear-polarization using the multi-channel detectors(virtual)
https://indico2.riken.jp/event/4174/

Aug. 3

4

Yuntao Wu(Chinese Academy of
Sciences)

5

Sohtaro Kanda(KEK)

Development of 6Li-loaded Halide Scintillators toward Neutron Detection (virtual)
Sep. 2https://indico2.riken.jp/event/4217/
Study of dynamical processes of muonic atom toward observation of parity nonconservation
effects (virtual)
https://indico2.riken.jp/event/4267/

Nov. 11

Subnuclear System Research Division1

Sinya Aoki
(Kyoto U.)

NT/RBRC Seminar
Conserved non-Noether charge in general relativity: Physical definition vs. Noether's 2nd
theorem (virtual)

Apr. 1

2

Katelin Schutz(McGill U.)

High-Energy Physics & RIKEN Theory Seminar
Astrophysical handles on searches for new particles (virtual)

Apr. 7

3

Owe Philipsen(Frankfurt U.)

RBRC Seminar
The QCD chiral phase transition for different numbers of flavours (virtual)

Apr. 14

4

Hiroyuki Tajima(U. Tokyo)

SNP Seminar
Cooper quartet correlations in multi-component fermionic systems (virtual)

Apr. 14

5

Shuai Zhao
(Old Dominion U.)

NT/RBRC Seminar
One-loop structure of twist-4 PDFs for gluon condensate and topological charge (hybrid)

Apr. 15

6Adrien Florio(BNL)

RBRC Seminar
Dynamics of the O(4) critical point in QCD (hybrid)

Apr. 21

7

Edmond Iancu(Institut de Physique
Theorique de Saclay)

NT/RBRC Seminar
Probing gluon saturation via diffractive jet production at the EIC (hybrid)

Apr. 22

8

Xiaoxuan Chu(BNL)

RBRC Seminar
Probing nonlinear gluon effects by forward di-hadron correlation (hybrid)

Apr. 28

9

Huey-Wen Lin(Michigan State U.)

NT/RBRC Seminar
Mapping nucleon parton distributions with lattice QCD (hybrid)

Apr. 29

10

Giuliano Giacalone(U. Heidelberg)

RBRC Seminar
Imprints of nucleon structure in high-energy nuclear collisions (virtual)

May 5

11

Felipe Attanasio(U. Heidelberg)

NT/RBRC Seminar
QCD equation of state via the complex Langevin method (hybrid)

May 6

12

Alessandro Nada
(Turin U.)

RBRC Seminar
Stochastic normalizing flows for lattice field theory (virtual)

May 12

13

Xuanbo Tong
(Chinese U. Hong Kong)

NT/RBRC Seminar
Perturbative calculations of gravitational form factors at large momentum transfer (hybrid)

May 13

14

Jim Talbert(Cambridge U.)

High-Energy Physics & RIKEN Theory Seminar
Towards an all-orders flavor formalism in the (geo)SM(EFT) and beyond (hybrid)

May 1915

Adrian Dumitru(Baruch College)

RBRC Seminar
Quark and gluon entanglement in the light-front wave function of the proton at moderate x(hybrid)

May 19- 399 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

16

Robert Szafron(BNL)

NT/RBRC Seminar
Soft-collinear effective field theory for gravity (hybrid)

May 2017

Mikhail Stephanov(UIC)

RBRC Seminar
Predictable randomness of relativistic hydrodynamics (hybrid)

May 2618

Soeren Schlichting(U. Washington)

NT/RBRC Seminar
Non-perturbative determination of the collisional broadening kernel and medium-induced
radiation in QCD plasmas (hybrid)

May 2719

Jessica Howard(UCI)

High-Energy Physics & RIKEN Theory Seminar
Dark matter freeze-out during SU(2)_L confinement (hybrid)

Jun. 220

Ming Li(North Carolina State U.)

NT/RBRC Seminar
Relating gluon bose correlation in nuclear wave function to near side ridge in deep inelastic
scattering (hybrid)

Jun. 3

21

Anke Biekoetter(Durham U.)

High-Energy Physics & RIKEN Theory Seminar
Standard model effective field theory - indirect constraints on new fundamental physics(hybrid)

Jun. 922

KC Kong(U. Kansas)

High-Energy Physics & RIKEN Theory Seminar
Double higgs production at the HL-LHC (hybrid)

Jun. 16

23

Tomoya Naito(iTHEMS, RIKEN)SNP Seminar
Isospin symmetry breaking in nuclear ground state (virtual)Jun. 22

24

Pier Francesco Monni(CERN)

High-Energy Physics & RIKEN Theory Seminar
Taming the complex dynamics of scattering events (hybrid)

Jun. 23

25

Kemal Tezgin(U. Connecticut)

RBRC Seminar
3D and 2D distributions of the energy-momentum tensor in a quark model (hybrid)

Jun. 23

26

Alba Soto Ontoso(IPhT)

NT/RBRC Seminar
PanScales parton showers for hadron collisions (hybrid)

Jun. 28

27

Tonia Venters(NASA)

High-Energy Physics & RIKEN Theory Seminar
Ultra-high energy cosmic rays: exploring the energy frontier by way of the cosmic frontier(hybrid)

Jun. 30

28

Stella Schindler(MIT)

NT/RBRC Seminar
Factorization connecting physical and lattice TMDs (hybrid)

Jul. 1

29

Denis Lacroix(U. Paris-Saclay)

SNP Seminar
Quantum computing description of atomic nuclei: challenges and opportunities (virtual)

Jul. 530

Kim Berghaus(Stony Brook U.)

High-Energy Physics & RIKEN Theory Seminar
Warm early dark energy (hybrid)

Jul. 731

Chun Shen(Wayne State U.)

RBRC Seminar
Longitudinal dynamics and particle production in relativistic nuclear collisions (hybrid)

Jul. 732

Julia Gehrlein(BNL)

High-Energy Physics & RIKEN Theory Seminar
Quo vadis neutrinoless double beta decay? (hybrid)

Jul. 833

Mikko Laine(U. Bern)

NT/RBRC Seminar
Heavy quark kinetic equilibration from the lattice (hybrid)

Jul. 834

Holmfridur Hannesdottir(IAS)

High-Energy Physics & RIKEN Theory Seminar
What is the iε for the S-matrix? (hybrid)

Jul. 1435

David Frenklakh(Stony Brook U.)

RBRC Seminar
Chirality distribution inside baryons in QCD_2 (hybrid)

Jul. 14

36

Zhite Yu
(Michigan State U.)

NT/RBRC Seminar
Exclusive single-diffractive hard scattering processes for probing the x-dependence ofgeneralized parton distributions (hybrid)

Jul. 15

37

Yair Mulian(Jyvaskyla U.)

NT/RBRC Seminar
Next-to-leading order photon+jet production (hybrid)

Jul. 25

38

Myung-Ki Cheoun(Soongsil U.)

SNP Seminar
Low Energy Nuclear Reactions for Carbon Isotopes, 17F and 17O (virtual)

Jul. 28- 400 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

39

Vladi Skokov(BNL)

RBRC Seminar
CGC density matrix (hybrid)

Jul. 28

40

Bianka Mecaj(Yale U.)

NT/RBRC Seminar
Conformal Colliders meet the LHC (hybrid)

Jul. 29

41

Werner Vogelsang(U. Tubingen)

NT/RBRC Seminar
Higher-order QCD corrections to semi-inclusive DIS and fragmentation functions (hybrid)

Aug. 12

42

Krzysztof Kutak
RBRC Seminar(Institute of Nuclear
Maximally entangled proton and charged hadron multiplicity in Deep Inelastic Scattering
Physics Polish Academy of(hybrid)
Sciences)

Aug. 18

43

Akio Tomiya(International
Professional U.
Technology)

RBRC Seminar
T-mu phase diagram using classical-quantum hybrid algorithm (hybrid)

Aug. 25

44

Andrea Shindler(Michigan State U.)

NT/RBRC Seminar
Electric dipole moments from lattice QCD (hybrid)

Aug. 26

45

Seth Koren(U. Chicago)High-Energy Physics & RIKEN Theory Seminar
Discrete symmetries, proton stability, and cosmological lithium (hybrid)

Sep. 1

46

Yuki Yokokura(RIKEN)RBRC Seminar
Entropy-area law from interior semi-classical degrees of freedom (hybrid)

Sep. 1

47

Georg Wolschin(Heidelberg U.)

SNP Seminar
In-medium bottomonium suppression in p-Pb and Pb-Pb collisions at LHC energies (virtual)

Sep. 248

Tomasz Stebel(Jagiellonian)

NT/RBRC Seminar
Sampling statistical systems with artificial neural networks (hybrid)

Sep. 249

Ian Moult(Yale U.)

High-Energy Physics & RIKEN Theory Seminar
Conformal colliders meet the LHC (hybrid)

Sep. 850

Lingfeng Li(Brown U.)

High-Energy Physics & RIKEN Theory Seminar
Jupiter missions as probes of dark matter (hybrid)

Sep. 15

51

Xiaojun Yao(MIT)

NT/RBRC Seminar
Pure quark and gluon observables (hybrid)

Sep. 15

52

Josh Tawabutr(Ohio State U.)

NT/RBRC Seminar
Recent developments in small-x helicity evolution (hybrid)

Sep. 1653

Christopher Monahan(College of William andMary)

High-Energy Physics & RIKEN Theory SeminarFirst principles’ calculations of the gluon structure of hadrons (hybrid)

Sep. 22

54

Claudio Bonanno(INFN)

NT/RBRC Seminar
Large-N SU(N) pure-gauge theories with milder topological freezing via parallel temperingon boundary conditions (hybrid)

Sep. 29

55

Amarjit Soni
(BNL)

High-Energy Physics & RIKEN Theory Seminar
Flavor anomalies, possible new physics and collider signals (hybrid)

Sep. 30

56

Guillaume Beuf
(NCBJ)

NT/RBRC Seminar
DIS at NLO in the dipole factorization and mass renormalization on the light-front (hybrid)

Sep. 30

57

Lucas Happ
(RIKEN)

SNP Seminar
Universality in one-dimensional quantum three-body systems (virtual)Oct. 358

Juan Pedersen(U. Tokyo)

RBRC Seminar
Reformulation of anomaly inflow on the lattice and construction of lattice chiral gauge
theories (hybrid)

Oct. 659

Yang-Ting Chien(Georgia State U.)

NT/RBRC Seminar
Probing hadronization with flavor correlations of leading particles in jets (hybrid)

Oct. 7

60

Martha Constantinou(Temple U.)

High-Energy Physics & RIKEN Theory Seminar
The structure of the proton from numerical simulations of lattice QCD (hybrid)

Oct. 13- 401 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

61

Scott Lawrence

RBRC Seminar
Probing the hydrodynamics of strongly coupled quantum field theories (hybrid)

Oct. 13

62

Ahmad Jafar Arifi(APCTP)

SNP Seminar
Mass spectra and wave functions of mesons in Light-front quark model (virtual)Oct. 14

63

Savvas Zafeiropoulos(CPT)

NT/RBRC Seminar
The extraction of light cone parton distributions from lattice quantum chromodynamics(hybrid)

Oct. 1464

Dennis Bollweg(BNL)

NT/RBRC Seminar
Lattice QCD thermodynamics from cumulants of conserved charge fluctuations (hybrid)

Oct. 20

65

Yuki Fujimoto(U. Washington)

NT/RBRC Seminar
Trace anomaly in neutron stars (hybrid)

Oct. 2166

Cora Dvorkin(Harvard U.)

High-Energy Physics & RIKEN Theory Seminar
The universe as a lab for new physics across cosmic times (hybrid)

Oct. 27

67

Waseem Kamleh(U. Adelaide)

RBRC Seminar
Emergent phenomena from centre vortices (hybrid)

Oct. 27

68

Matthew Walters(EPFL)

NT/RBRC Seminar
Towards a nonperturbative construction of the S-matrix (hybrid)

Oct. 28

69

Anna Suliga (U.
California)

High-Energy Physics & RIKEN Theory Seminar
Towards probing the diffuse supernova neutrino background in all flavors (hybrid)

Nov. 370

Jack Holden(Southampton U.)

RBRC Seminar
Partial deconfinement (hybrid)

Nov. 371

Abhiram Kaushik(Zagreb U.)

NT/RBRC Seminar
Transverse single spin asymmetry at two loops (hybrid)

Nov. 472

Friederike Ihssen(ITP Heidelberg)

RBRC Seminar
Lee-Yang zeroes from the functional renormalisation group (hybrid)

Nov. 1073

Koji Miwa Koji Miwa
(Tohoku U.)

SNP Seminar
Recent progress and future prospects of hyperon nucleon scattering experiment at J-PARC(virtual)

Nov. 15

74

Florian Herren(Fermilab)

High-Energy Physics & RIKEN Theory Seminar
A NLL accurate parton shower in sherpa (hybrid)

Nov. 17

75

Sanjin Benic(Zagreb U.)

NT/RBRC SeminarOn the odderon mechanism for transverse single spin asymmetry in the Wilczek-Wandzura
approximation (hybrid)

Nov. 18

76

Fei Yan(Rutgers U.)

RBRC Seminar
Entanglement entropy in (1+1)-d with defects (hybrid)

Dec. 1

77

Fernando Romero-López(MIT)

NT/RBRC Hybrid Seminar
Flow-based sampling for lattice field theories (hybrid)

Dec. 278

Ilaria Brivio(U. Copenhagen)High-Energy Physics & RIKEN Theory Seminar
The hunt for non-resonant signals of new physics at the LHC (hybrid)

Dec. 879

Hersh Singh(U. Washington)

RBRC Seminar
From topological theta vacua to asymptotic freedom: Qubit models, sign problems, andanomalies (hybrid)

Dec. 880

Simone Rodini(Ecole Polytechnique)

NT/RBRC Hybrid Seminar
TMD factorization at next-to-leading power (hybrid)

Dec. 981

Jinglun Li(U. Ulm)

SNP Seminar
Product spin and binding energy propensities for three-body recombination of ultracold
atoms (virtual)Dec. 15

82

Theodore Jacobson(U. Minnesota)

NT/RBRC Hybrid Seminar
1-form symmetry versus large N QCD (hybrid)

Dec. 16

83

Hai-tao Shu(Regensburg U.)

NT/RBRC Hybrid Seminar
Shear viscosity and bulk viscosity from lattice QCD calculation (hybrid)

Jan. 6- 402 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

84

Stefano Profumo(U. California)

High-Energy Physics & RIKEN Theory Seminar
The primordial black holes variations (hybrid)

Jan. 12

85

William Horowitz(U. of Cape Town)

NT/RBRC Hybrid Seminar
Small system phenomenology (hybrid)

Jan. 13

86

Cenxi Yuan
(IFCEN)

SNP Seminar
Configuration-Interaction Shell Model and Its Application in Exotic Nuclei (virtual)Jan. 16

87

Brenda Frye
(U. Arizona)

High-Energy Physics & RIKEN Theory Seminar
Unscrambling galaxy cluster fields in the JWST era (hybrid)

Jan. 19

88

Francesco Riva
(Geneva U.)

RBRC Seminar
Positivity of effective field theories and large-N QCD (hybrid)

Jan. 19

89

Alberto Martin-Caro(IGFAE)

NT/RBRC Hybrid Seminar
Skyrmions: from light nuclei to neutron stars (hybrid)

Jan. 20

90

Silvia Ferrario Ravasio(Oxford U.)

High-Energy Physics & RIKEN Theory Seminar
Dissecting hadronisation corrections for collider physics (hybrid)

Jan. 26

91

Wenbin Zhao
(Harbin U. of Science andTechnology)

RBRC Seminar
The 3D structure of anisotropic flow in small collision systems at the RHIC and LHC (hybrid)

Jan. 26

92

Gopolang Mohlabeng(U. California)

High-Energy Physics & RIKEN Theory Seminar
Terrestrial planet probes for low mass dark matter (hybrid)

Feb. 2

93

Tongyan Lin(U. California)

High-Energy Physics & RIKEN Theory Seminar
Dark matter direct detection from single phonons to nuclear recoils (hybrid)

Feb. 994

Kazuki Ikeda(Stony Brook U.)

RBRC Seminar
Demonstration of quantum energy teleportation by superconducting quantum processors
and implications for communications and high energy physics (hybrid)

Feb. 995

Marvin Schnubel(Mainz U.)

High-Energy Physics & RIKEN Theory Seminar
Flavour probes of axion-like particles (hybrid)

Feb. 1096

Rajeev Singh(Stony Brook U.)

NT/RBRC Hybrid Seminar
Relativistic hydrodynamics with spin for massive spin-1/2 fermions with and without particle
collisions (hybrid)

Feb. 1097Admir Greljo(Bern U.)

High-Energy Physics & RIKEN Theory Seminar
Model building and phenomenology with leptoquarks (hybrid)

Feb. 16

98

Paul Hotzy(Tech. U.)

RBRC Seminar
Stabilizing complex Langevin for real-time gauge theories with an anisotropic kernel (online)

Feb. 1699

Fernando Romero-López(MIT)

NT/RBRC Hybrid Seminar
Flow-based sampling for lattice gauge theories (hybrid)

Feb. 17100

Fangcheng He(Chongqing U. of
Education)

RBRC Seminar
Charmonium spin decomposition from Lattice QCD (hybrid)

Feb. 23

101

Irene Valenzuela(CERN)

High-Energy Physics & RIKEN Theory Seminar
Swampland Constraints and the Dark Dimension (hybrid)

Mar. 2

102

Marton Lajer(BNL)

RBRC Seminar
Scattering from energy levels: Truncated Spectrum Approach and Lüscher's method for theϕ4 1+1 theory (hybrid)

Mar. 2103

Jesse Stryker(Maryland U.)

NT/RBRC Hybrid Seminar
Loop-string-hadron formulation of an SU(3) gauge theory with dynamical quarks (hybrid)

Mar. 3104

Masaru Hongo(Niigata U.)

SNP Seminar
Effective field theoretical approach to weakly bound Borromean nuclei (virtual)Mar. 8105

Shuzhe Shi(Stony Brook U.)

RBRC Seminar
Real-time non-perturbative dynamics of jet production in Schwinger model: quantum
entanglement and vacuum modification (hybrid)

Mar. 9106

Daniel Pablos Alfonso(INFN)

NT/RBRC Seminar
Looking for evidence of color decoherence in jet observables (hybrid)

Mar. 10- 403 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

107

Linda Carpenter(Ohio State U.)

High-Energy Physics & RIKEN Theory Seminar
LEX-EFT: The light exotics effective field theory (hybrid)

Mar. 16108

Sipaz Sharma(Bielefeld)

RBRC Seminar
Charm fluctuations as a probe for deconfinement from lattice QCD (hybrid)

Mar. 16

109

Niklas Muller(U. Washington)

NT/RBRC Seminar
What entanglement structure can tell us about lattice gauge theories (hybrid)

Mar. 17

110

Andrés Luna
(Niels Bohr Institute)

High-Energy Physics & RIKEN Theory Seminar
Scattering Amplitudes for Spinning Binaries (hybrid)

Mar. 23

111

Hideto En'yo(RIKEN)

Special RBRC Seminar
My 40 years of looking up to the world of Nambu (hybrid)

Mar. 23112

Vladimir Braun(Regensburg U.)

NT/RBRC Seminar
Conformal symmetry in strong interactions (hybrid)

Mar. 24

113

Matthew Baumgart(Arizona State U.)

High-Energy Physics & RIKEN Theory Seminar
Attacking heavy dark matter on two fronts (hybrid)

Mar. 30High Energy / Nuclear Theory / RIKEN seminars → https://indico.bnl.gov/category/228/
RBRC Seminar → https://www.bnl.gov/riken/events/- 404 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

Events (April 2022―March 2023)
RNC
Apr. 23

Wako Open Campus

May 26The 29th RBRC Management Steering Committee (MSC)

Jul. 22

The 19th Industrial Program Advisory Committee (In-PAC)

Aug. 22–25

The 22nd Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)

Oct. 28

Memorial Event for Dr. Yoshio Nishina

Dec. 1–3

The 22nd Program Advisory Committee for Nuclear Physics Experiments at RI Beam Factory (NP-PAC)

Dec. 12–Jan.
6
Dec. 23–Jan.
10

The 20th Industrial Program Advisory Committee (In-PAC)
The 23rd Program Advisory Committee for Materials and Life Science Researches at RIKEN Nishina Center (ML-PAC)

CNS
Aug. 20–24

The 21st CNS International Summer School (A3F-CNSSS22)
https://indico2.cns.s.u-tokyo.ac.jp/event/198/

KEK
Sep. 1–2

SSRI-PNS Collaboration meeting 2022
https://indico2.riken.jp/event/4202/timetable/?view=standard_inline_minutes- 405 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

Press Releases (April 2022−March 2023)
RNC
Apr. 27

α-Clustering in atomic nuclei from first principles with statistical learning and the
Hoyle state character
https://www.riken.jp/press/2022/20220427_2/index.html

T. Otsuka, T. Abe, Nuclear Spectroscopy
Laboratory

Apr. 28First Application of Mass Measurement with the Rare-RI Ring Reveals the Solar rProcess Abundance Trend at A = 122 and A = 123
https://www.riken.jp/press/2022/20220428_2/index.html

T. Uesaka, S. Naimi, H. Fu Li, Y. Yamaguchi,
Spin Isospin Research Laboratory, Rare RI
Ring TeamMay 25

Variability in the net ecosystem productivity (NEP) of seaweed farms
https://www.riken.jp/press/2022/20220525_1/index.html

Y. Sato, Ion Beam Breeding Team

Jun. 23

Observation of a correlated free four-neutron system
https://www.riken.jp/press/2022/20220623_1/index.html

H. Otsu, V. Panin, SAMURAI Team, Spin
Isospin Laboratory

Sep. 21

Proton Hyperpolarization Relay from Nanocrystals to Liquid Water
https://www.riken.jp/press/2022/20220921_2/index.html

T. Uesaka, K. Tateishi, Spin isospin
Laboratory

Sep. 28

A CLAVATA3-like gene acts as a gynoecium suppression function in White Campion
https://www.riken.jp/press/2022/20220928_1/index.html

T. Abe, Beam Mutagenesis Group

Oct. 19β-Delayed One and Two Neutron Emission Probabilities South-East of 132Sn and the
Odd-Even Systematics in r-Process Nuclide Abundances
https://www.riken.jp/press/2022/20221019_1/index.html

V. Ho Phong, S. Nishimura, H. Sakurai,Radioactive Isotope Physics Laboratory

Nov. 17

Discovery of 39Na
https://www.riken.jp/press/2022/20221117_3/index.html

T. Kubo, D. S. Ahn, H. Suzuki, ResearchInstruments Group

Nov. 17

Targeted α-therapy using astatine (211At)-labeled PSMA1, 5, and 6: a preclinicalevaluation as a novel compound
https://www.riken.jp/press/2022/20221117_2/index.html

H. Haba, Nuclear Chemistry Research Team,RI Application Research Group

Nov. 24

Direct Determination of the Activation Energy for Diffusion of OH Radicals on Water
Ice
https://www.riken.jp/press/2022/20221124_1/index.html

Y. Nakai, Radioactive Isotope Physics
Laboratory

Nov. 25

Polarized x-rays from a magnetar
https://www.riken.jp/press/2022/20221125_2/index.html

K. Uchiyama, High Energy Astrophysics
Laboratory

Jan. 6

Observation of non-existence of new magic number in titanium and vanadium
neutron rich isotopes
https://www.riken.jp/press/2023/20230106_2/index.html

H. Ishiyama, SLOWRI Team

Feb. 22Long-term density trend in the mesosphere and lower thermosphere fromoccultations of the crab nebula with X-ray astronomy satellites
https://www.riken.jp/press/2023/20230222_2/index.html

Y. Motizuki, Astro-Glaciology Research Group

Mar. 2Singlet fission as a polarized spin generator for dynamic nuclear polarization
https://www.riken.jp/press/2023/20230302_1/index.html

T. Uesaka, K. Tateishi, Spin isospin Laboratory

Mar. 27

Chiral symmetry restoration at high matter density observed in pionic atoms
https://www.riken.jp/press/2023/20230327_1/index.html

T. Nishi, K. Itahashi, Researcher at the
Accelerator Group, Meson Science Laboratory

KEK
Jan. 6

Mar. 31

チタン・バナジウム中性子過剰同位体で新魔法数の消失を観測 ～精密質量測定による原子核構造のより深い理解に期待～https://www.kek.jp/ja/press/202301061400/
40 年ぶりに中性子過剰なウラン同位体を新発見 ～ウランの起源解明に期待～
https://www.kek.jp/ja/press/202304010000/- 406 -

KEK, RIKEN, Osaka University

KEK, RIKEN

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

News (April 2022−March 2023)
RNC
Apr. 22

超伝導リングサイクロトロン、ギネス世界記録™に登録
https://www.riken.jp/pr/news/2022/20220422_2/index.html

May 17

関口仁子客員研究員が猿橋賞を受賞
https://www.riken.jp/pr/news/2022/20220517_2/index.html

Nov. 9「仁科芳雄記念室お披露目会」およびシンポジウム「理化学研究所仁科研究室のキセキ」を開催
https://www.riken.jp/pr/news/2022/20221109_1/index.html

Mar. 17

理研ーRAL 記念式典を開催
https://www.riken.jp/pr/news/2023/20230317_1/index.html

Mar. 13

仁科型電離箱 2 号機の日本天文遺産認定
https://www.riken.jp/pr/news/2023/20230313_2/index.html
理研栄峰賞、理研梅峰賞の授与

Mar. 23

理研栄峰賞: 羽場 宏光 「アルファ線核医学治療に向けたアスタチン-211 の大量製造技術の開発」
理研梅峰賞: 阿部 喬、大塚 孝治 「炭素-12 原子核のホイル状態における第一原理計算」
山口 由高 「元素起源の謎の解明に向けた世界最速質量測定法確立」
https://www.riken.jp/pr/news/2023/20230323_1/index.html- 407 -

Ⅶ. APPENDICESRIKEN Accel. Prog. Rep. 56 (2023)

List of Preprints (April 2022―March 2023)
RIKEN NC-NP
Not Applicable

RIKEN NC-AC
Not Applicable

RIKEN MP
Not Applicable

RIKEN QHP
515

Isospin symmetry breaking in the charge radius difference of mirror nuclei

T. Naito et al.

516

Interaction potentials for two-particle states with non-zero total momenta in lattice QCD

Y. Akahoshi and S. Aoki

CNS-REP101

CNS Annual Report 2021

H. Nagahama

Nishina Center Preprint server (not including Partner Institution) can be found at
http://nishina-preprints.riken.jp/- 408 -

理化学研究所

埼玉県 和光市 広沢
RIKEN 2023-039
ISSN 0289-842X