原子核のスピン分布制御という新手法を用いた中性子超過剰核の構造の研究

• Project/Area Number: 16J05919
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Single-year Grants
• Section: 国内
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: 西畑 洸希 国立研究開発法人理化学研究所, 仁科加速器科学研究センター, 特別研究員(PD)
• Project Period (FY): 2016-04-22 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
• Keywords: 不安定原子核

Outline of Annual Research Achievements

本研究は中性子数（もしくは陽子数）が陽子数(中性子数)に比べて極端に多い中性子(陽子)過剰不安定原子核構造はどのようになっているか、という原子核物理学の重要課題の一つとなっている。その中でも中性子数20付近の中性子過剰な原子核の構造はその特異な構造から非常に注目を集めている原子核領域である。本研究では、中性子過剰なNe同位体の基底状態について基本的な物理学量である電磁気モーメントを測定することで、基底状態の単一粒子状態や変形について系統的なデータを取得し、中性子数20領域の詳細な原子核構造を議論することを目的とする。
本研究では中性子過剰なNeの電磁気モーメントを測定するために、ベータNMRと空間的にスピンをある方向に偏らせた(スピン偏極した)不安定核ビームを組み合わせるという新たな手法を考案し、そのために必要な開発研究を行った。希ガスであるNeでのベータNMRに利用可能な停止素材のデータは非常に少なく、この研究には、まずNeを用いてベータNMRが可能な単結晶素材を探す必要がある。そのために、昨年度理化学研究所の不安定原子核生成装置RIPSを用いて実験を行った。その結果について本年度詳細な解析を行い、ZnOがNeのベータNMRに非常に有効であると新たに分かった。本年度は、その結果について解析を行い、論文としてまとめている。
加えて、本年度は実施できなかったがスピン整列ビームを用いての原理実証実験も放射線医学総合研究所のHIMACにて計画しており、本年度はその準備も行った。この実験は、理化学研究所RIBFで計画している中性子過剰なNeの本実験と同じシステムを用いるため、その測定システムの構築も本年度行った。

Research Progress Status

平成30年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

平成30年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Structure of Mg31: Shape coexistence revealed by β-γ spectroscopy with spin-polarized Na31 (2019)
  • Author(s): Nishibata H.、Kanaya S.、Shimoda T.、Odahara A.、Morimoto S.、Yagi A.、Kanaoka H.、Pearson M. R.、Levy C. D. P.、Kimura M.、Tsunoda N.、Otsuka T.
  • Journal Title: Physical Review C Volume: 99 Issue: 2 Pages: 024322-024322
  • DOI: 10.1103/physrevc.99.024322
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Identification of New Neutron-Rich Isotopes in the Rare-Earth Region Produced by 345 MeV/nucleon 238U (2018)
  • Author(s): N.Fukuda, T.Kubo, D.Kameda, N.Inabe, H.Suzuki, Y.Shimizu, H.Takeda, K.Kusaka, Y.Yanagisawa, M.Ohtake, H. Nishibata 他
  • Journal Title: Journal of the Physical Society of Japan Volume: 87 Issue: 1 Pages: 014202-014202
  • DOI: 10.7566/jpsj.87.014202
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Observation of New Neutron-rich Isotopes among Fission Fragments from In-flight Fission of 345 MeV/nucleon 238U: Search for New Isotopes Conducted Concurrently with Decay Measurement Campaigns (2018)
  • Author(s): Shimizu Yohei、et al.
  • Journal Title: Journal of the Physical Society of Japan Volume: 87 Issue: 1 Pages: 014203-014203
  • DOI: 10.7566/jpsj.87.014203
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Isomer-delayed γ-ray spectroscopy of A=159-164 midshell nuclei and the variation of K-forbidden E1 transition hindrance factors (2017)
  • Author(s): Patel Z.、et al.
  • Journal Title: Physical Review C Volume: 96 Issue: 3 Pages: 034305-034305
  • DOI: 10.1103/physrevc.96.034305
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Observation of a γ -decaying millisecond isomeric state in 128 Cd 80 (2017)
  • Author(s): Jungclaus A.、et al.
  • Journal Title: Physics Letters B Volume: 772 Pages: 483-488
  • DOI: 10.1016/j.physletb.2017.07.006
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Observation of new neutron-rich Mn, Fe, Co, Ni, and Cu isotopes in the vicinity of Ni78 (2017)
  • Author(s): Sumikama T.、et al.
  • Journal Title: Physical Review C Volume: 95 Issue: 5 Pages: 051601-051601
  • DOI: 10.1103/physrevc.95.051601
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Shell Evolution towards Ni78: Low-Lying States in Cu77 (2017)
  • Author(s): Sahin E.、et al.
  • Journal Title: Physical Review Letters Volume: 118 Issue: 24 Pages: 242502-242502
  • DOI: 10.1103/physrevlett.118.242502
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] β-decay scheme of Te140 to I140: Suppression of Gamow-Teller transitions between the neutron h9/2 and proton h11/2 partner orbitals (2017)
  • Author(s): Moon B.、et al.
  • Journal Title: Physical Review C Volume: 96 Issue: 1 Pages: 014325-014325
  • DOI: 10.1103/physrevc.96.014325
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Nuclear structure and b-decay schemes for Te nuclides beyond N = 82 (2017)
  • Author(s): B. Moon, ..., S. Nishimura et al.
  • Journal Title: Physical Review C Volume: 95 Issue: 4 Pages: 044322-044322
  • DOI: 10.1103/physrevc.95.044322
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Shape coexistence in the N=19 neutron-rich nucleus 31Mg explored by β-γ spectroscopy of spin-polarized 31Na (2017)
  • Author(s): H.Nishibata, T.Shimoda, A.Odahara, S.Morimoto, S.Kanaya, A.Yagi, H.Kanaoka, M.R.Pearson, C.D.P.Levy, M.Kimura
  • Journal Title: Physics Letters Volume: B767 Pages: 81-85
  • DOI: 10.1016/j.physletb.2017.01.049
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] beta-Decay Half-Lives of Neutron-Rich Cs-55 to Ho-67: Experimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation (2017)
  • Author(s): J. Wu, H. Baba, T. Isobe, et al.
  • Journal Title: Physical Review Letters Volume: 118 Issue: 7 Pages: 072701-072701
  • DOI: 10.1103/physrevlett.118.072701
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] The role of core excitations in the structure and decay of the 16+ spin-gap isomer in 96Cd (2017)
  • Author(s): P.J.Davies, H.Grawe, K.Moschner, A.Blazhev, R.Wadsworth, P.Boutachkov, F.Ameil, A.Yagi, H.Baba, T.Back, M.Dewald, P.Doornenbal, T.Faestermann, A.Gengelbach, J.Gerl, R.Gernhaeuser, S.Go, M.Gorska, E.Gregor. H. Nishibata 他
  • Journal Title: Phys. Lett. B Volume: 767 Pages: 474-479
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] New K isomers in the neutron-rich N=100 isotones 162Sm, 163Eu, and 164Gd (2017)
  • Author(s): R. Yokoyama, H. Baba, K. Ieki, et al.
  • Journal Title: Physical Review C Volume: 95 Issue: 3 Pages: 034313-034313
  • DOI: 10.1103/physrevc.95.034313
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Large-scale shell model study of the newly found isomer in 136La (2016)
  • Author(s): E.Teruya, N.Yoshinaga, K.Higashiyama, H.Nishibata, A.Odahara, T.Shimoda
  • Journal Title: Phys. Rev. C Volume: 94 Issue: 1 Pages: 014317-014317
  • DOI: 10.1103/physrevc.94.014317
  • Peer Reviewed / Open Access
• [Journal Article] Proton-hole and core-excited states in the semi-magic nucleus In-131(82) (2016)
  • Author(s): J. Taprogge, H. Baba, T. Isobe, et al.
  • Journal Title: European Physical Journal A Volume: 52 Issue: 11 Pages: 347-347
  • DOI: 10.1140/epja/i2016-16347-y
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] First Results on the Excited States in 77Cu (2016)
  • Author(s): E.Sahin, F.L.Bello Garrote, A.Gorgen, G.de Angelis, M.Niikura, S.Nishimura, D.Mengoni, Z.Xu, H.Baba, F.Browne, P.Doornenbal, S.Franchoo, G.Guillaume, T.Isobe, P.R.John, H.S.Jung, K.K.Hadynska-Klek, Z.Li, G.Lorusso, H. Nishibata 他
  • Journal Title: Acta Phys. Pol. B Volume: 47 Issue: 3 Pages: 889-895
  • DOI: 10.5506/aphyspolb.47.889
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Magnetic moment of the 13/2+ isomeric state in 69Cu: Spin alignment in the one-nucleon removal reaction (2016)
  • Author(s): A.Kusoglu, G.Georgiev, C.Sotty, D.L.Balabanski, A.Goasduff, Y.Ishii, Y.Abe, K.Asahi, M.Bostan, R.Chevrier, M.Chikamori, J.M.Daugas, T.Furukawa, H.Nishibata, Y.Ichikawa, Y.Ishibashi, R.Lozeva, H.Miyatake, D.Nagae, T.Nanao 他
  • Journal Title: Phys. Rev. C Volume: 93 Issue: 5
  • DOI: 10.1103/physrevc.93.054313
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] beta decay of semi-magic Cd-130: Revision and extension of the level scheme of In-130 (2016)
  • Author(s): A. Jungclaus, H. Baba, T. Isobe, et al.
  • Journal Title: Physical Review C Volume: 94 Issue: 2 Pages: 024303-024303
  • DOI: 10.1103/physrevc.94.024303
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] First observation of γ rays emitted from excited states south-east of 132Sn: The π g-9/2 x νf7/2 multiplet of 132In83 (2016)
  • Author(s): A. Jungclaus, ..., S. Nishimura et al.
  • Journal Title: Physical Review C Volume: 93 Issue: 4 Pages: 041301-041301
  • DOI: 10.1103/physrevc.93.041301
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] μs isomers of Nd-158,Nd-160 (2016)
  • Author(s): E. Ideguchi, H. Baba, T. Isobe, et al.
  • Journal Title: Physical Review C Volume: 94 Issue: 6 Pages: 064322-064322
  • DOI: 10.1103/physrevc.94.064322
  • Peer Reviewed / Int'l Joint Research
• [Presentation] 偏極Naビームで探る中性子過剰原子核30Mg, 31Mgの多様な原子核構造 (2019)
  • Author(s): 西畑 洸希
  • Organizer: 日本物理学会
  • Invited
• [Presentation] Structure of neutron-rich 31Mg by β-decay spectroscopy of spin-polarized 31Na (2019)
  • Author(s): H. Nishibata
  • Organizer: 5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
  • Int'l Joint Research
• [Presentation] Shape coexistence in 31Mg revealed by b-g and b-g-n spectroscopy with spin-polarized 31Na (2018)
  • Author(s): H. Nishibata
  • Organizer: The IX International Symposium on Exotic Nuclei (EXON2018)
  • Int'l Joint Research / Invited
• [Presentation] スピン偏極 スピン偏極 スピン偏極 スピン偏極 23Ne ビームを用いた単結晶電場勾配測定 (2017)
  • Author(s): 西畑 洸希
  • Organizer: 日本物理学会
• [Presentation] Shape coexistence in neutron-rich 31Mg investigated by beta-gamma spectroscopy of spin-polarized 31Na (2017)
  • Author(s): H. Nishibata
  • Organizer: The third International Conference on Advances in Radioactive Isotope Science, ARIS2017
  • Int'l Joint Research
• [Presentation] Various structures of the neutron-rich nucleus 31Mg investigated by beta-gamma spectroscopy of spin-polarized 31Na (2016)
  • Author(s): H. Nishibata
  • Organizer: SPIN2016
  • Place of Presentation: Illinois, America
  • Year and Date: 2016-09-25
  • Invited
• [Presentation] Various Structure In Neutron-rich 31Mg Studied By Using Spin-polarized 31Na Beam (2016)
  • Author(s): H. Nishibata
  • Organizer: INPC2016
  • Place of Presentation: Adelaide, Australia
  • Year and Date: 2016-09-11