励起準位寿命測定による三軸非対称変形原子核の研究

• Project/Area Number: 14J08718
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Single-year Grants
• Section: 国内
• Research Field: Condensed matter physics I
• Research Institution: The University of Tokyo
• Principal Investigator: 谷内 稜 東京大学, 理学系研究科, 特別研究員(DC1)
• Project Period (FY): 2014-04-25 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥2,800,000 (Direct Cost: ¥2,800,000); Fiscal Year 2016: ¥900,000 (Direct Cost: ¥900,000); Fiscal Year 2015: ¥900,000 (Direct Cost: ¥900,000); Fiscal Year 2014: ¥1,000,000 (Direct Cost: ¥1,000,000)
• Keywords: 不安定核 / 理研RIBF / 二重魔法数 / 不安定核研究 / GRETINA

Outline of Annual Research Achievements

ここ20年の不安定原子核の研究により安定な原子核に比べて陽子・中性子比が大きく異なる原子核における殻構造が変化し，安定核近傍では魔法性を持っていた原子核が不安定性を増すにつれ変形し魔法性を失ったり，新たな閉殻構造が生じたりすることが実験的に確認されるようになった。中性子過剰な“二重魔法数”を持つ原子核である78Niが魔法性を持ち続け球形構造を維持しているかは長年の謎であった。この謎の解明のため当該研究員は2014年5月に理化学研究所RIBFにおいて一陽子ならびに二陽子ノックアウト反応による78Niの励起準位探索実験を行った。当該年度は原子核反応理論との比較に基づいた一陽子ノックアウト反応により励起される準位の理解をすすめた。同時に二核子ノックアウト反応においてのみ励起される準位の理解を行うべく，新たに殻計算の理論物理学者との議論を行った。同時に，投稿論文の執筆をすすめた。
また，同時に密度の高いシンチレーターを用いた高検出効率のγ線エネルギー計測アレイの開発を行った。理研RIBFに代表されるインビーム核分光実験は，安定な原子核から遠く離れた（アイソスピンが大きな）不安定原子核の性質を知るうえで最も強力な手法である。現在，理研では脱励起γ線をNaI(Tl)シンチレーターアレイDALI2を用いて測定を行っている。事象数の限られるより中性子過剰な原子核や，よりγ線多重度の高い高励起準位測定に利用する為，新たな高検出効率の検出器の検討を行った。近年新たに開発されたGAGGシンチレーターはNaI(Tl)と同程度またはそれ以上のエネルギーならびに時間分解能を持つうえ，潮解性がなく，γ線の検出効率が極めて高いため，本シンチレーターを用いた検出器のシミュレーションや，プロトタイプを用いたテストに着手した。

Research Progress Status

28年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

28年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] CEAサクレー/IPNオルセー(フランス)
• [Journal Article] Are There Signatures of Harmonic Oscillator Shells Far from Stability? First Spectroscopy of Zr-110 (2017)
  • Author(s): N. Paul, H. Baba, et al.
  • Journal Title: Physical Review Letters Volume: 118 Issue: 3 Pages: 032501-032501
  • DOI: 10.1103/physrevlett.118.032501
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Spallation reaction study for the long-lived fission product ¹⁰⁷Pd (2017)
  • Author(s): H. Wang, T. Isobe, et al.
  • Journal Title: Progress of Theoretical and Experimental Physics Volume: 2017 Issue: 2
  • DOI: 10.1093/ptep/ptw187
  • URL: https://pure.teikyo.jp/en/publications/cfef3b19-4631-42de-918a-eacb750afbd1
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Type II shell evolution in A=70 isobars from the N >= 40 island of inversion (2017)
  • Author(s): A.I. Morales, H. Baba, T. Isobe, et al.
  • Journal Title: Physics Letters B Volume: 765 Pages: 328-333
  • DOI: 10.1016/j.physletb.2016.12.025
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Observation of isoscalar and isovector dipole excitations in neutroni-rich 20O (2017)
  • Author(s): N. Nakatsuka, H. Baba,Y. Kondo, T. Nakamura, Y. Togano et al.
  • Journal Title: Physics Letters B Volume: 768 Pages: 387-392
  • DOI: 10.1016/j.physletb.2017.03.017
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Inelastic scattering of 72,74Ni off a proton target (2016)
  • Author(s): M. L. Cortes, R. Taniuchi, et. al.
  • Journal Title: Phys.: Conf. Ser. Volume: 724 Pages: 012008-012008
  • DOI: 10.1088/1742-6596/724/1/012008
  • Int'l Joint Research
• [Journal Article] Low-lying excitations in 72Ni (2016)
  • Author(s): A.I. Morales, H. Baba, T. Isobe, et al.
  • Journal Title: Physical Review C Volume: 93 Issue: 3 Pages: 034328-034328
  • DOI: 10.1103/physrevc.93.034328
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Spallation reaction study for fission products in nuclear waste: class FormattedString { value: Cross section measurements for ¹³⁷Cs and ⁹⁰Sr on proton and deuteron } (2016)
  • Author(s): H. Wang, T. Isobe, et al.
  • Journal Title: Physics Letter B Volume: 754 Pages: 104
  • DOI: 10.1016/j.physletb.2015.12.078
  • URL: https://localhost/en/publications/4735163c-d264-46bc-a3b6-2028299b44d9
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] FIRST RESULTS ON THE EXCITED STATES IN 77Cu (2016)
  • Author(s): E. Sahin, R.Taniuchi, et. al,
  • Journal Title: ACTA PHYSICA POLONICA B Volume: 47 Pages: 889-889
  • Int'l Joint Research
• [Journal Article] Extension of the N=40 Island of Inversion towards N=50: Spectroscopy of Cr-66, Fe-70,Fe-72 (2015)
  • Author(s): C. Santamaria, H. Baba, T. Isobe, et al.
  • Journal Title: Physical Review Letters Volume: 115 Issue: 19 Pages: 192501-192501
  • DOI: 10.1103/physrevlett.115.192501
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Low-Lying Structure of 50Ar and the N=32 Subshell Closure (2015)
  • Author(s): D. Steppenbeck, S. Takeuchi, N. Aoi, P. Doornenbal, M. Matsushita, H. Wang, Y. Utsuno, H. Baba, S. Go, J. Lee, K. Matsui, S. Michimasa, T. Motobayashi, D. Nishimura, T. Otsuka, H. Sakurai, Y. Shiga, N. Shimizu, P.-A. Soderstrom, T. Sumikama, R. Taniuchi, J.J. Valiente-Dobon, K. Yoneda
  • Journal Title: Physical Review Letters Volume: 114 Issue: 25 Pages: 252501-252501
  • DOI: 10.1103/physrevlett.114.252501
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Two-hole structure outside 78Ni: Existence of a μs isomer of 76Co and β decay into 76Ni (2015)
  • Author(s): P.-A. Soderstrom, S. Nishimura, Z.Y. Xu, K. Sieja, V. Werner, P. Doornenbal, G. Lorusso, F. Browne, G. Gey, H.S. Jung, T. Sumikama, J. Taprogge, Zs. Vajta, H. Watanabe, J. Wu, et al.
  • Journal Title: Physical Review C Volume: 92 Issue: 5 Pages: 051305-051305
  • DOI: 10.1103/physrevc.92.051305
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Neutron-driven collectivity in light tin isotopes: Proton inelastic scattering from Sn-104 (2015)
  • Author(s): A. Corsi, H. Baba, T. Isobe, et al.
  • Journal Title: Physics Letters B Volume: 743 Pages: 451-455
  • DOI: 10.1016/j.physletb.2015.03.018
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Development of a total-kinetic-energy counter for high-rate experiments at ZeroDegree spectrometer (2015)
  • Author(s): R. Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report 2014 Volume: 48 Pages: 210-210
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Collectivity of neutron-rich Cr and Fe toward N=50 (2015)
  • Author(s): V. Werner, R.Taniuchi, et. al,
  • Journal Title: EPJ Web of Conferences Volume: 107 Pages: 03007-03007
  • Int'l Joint Research
• [Journal Article] β-Decay half-lives of 76,77Co, 79,80Ni and 81Cu: experimental indication of doubly magic 78Ni (2015)
  • Author(s): Z. Y. Xu, R.Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report Volume: 48 Pages: 3-3
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] First campaign of the SEASTAR project (2015)
  • Author(s): P. Doornenbal, R.Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report Volume: 48 Pages: 5-5
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Fragmentation of 137Cs and 90Sr on proton and deuterium (2015)
  • Author(s): H. Wang, R.Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report Volume: 48 Pages: 6-6
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Intermediate-energy Coulomb excitation of 104Sn: Moderate E2 strength decrease approaching 100Sn (2015)
  • Author(s): P. Doornenbal, R.Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report Volume: 48 Pages: 4-4
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] In-beam γ-ray spectroscopy of 50Ar (2015)
  • Author(s): D. Steppenbeck, R.Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report Volume: 48 Pages: 37-37
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Study of the pygmy-dipole resonances of 132Sn and 128Sn in inelastic α-scattering (2015)
  • Author(s): J. Tscheuschner, R.Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report Volume: 48 Pages: 39-39
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Experimental study of isoscalar and isovector dipole resonances in neutron-rich oxygen isotopes (2015)
  • Author(s): N. Nakatsuka, R.Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report Volume: 48 Pages: 38-38
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Coulomb excitation of 130Cd (2015)
  • Author(s): H. Wang, R.Taniuchi, et. al,
  • Journal Title: RIKEN Accelerator Progress Report Volume: 48 Pages: 40-40
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] β-Decay Half-Lives of 76, 77Co, 79, 80Ni and 81Cu Experimental Indication of a Doubly Magic 78Ni (2014)
  • Author(s): Z.Y. Xu, S. Nishimura, G. Lorusso, F. Browne, P. Doornenbal, G. Gey, H.-S. Jung, Z. Li, M. Niikura, P.-A. Soderstrom, T. Sumikama, J. Taprogge, Zs. Vajta, H. Watanabe, J. Wu, A. Yagi, K. Yoshinaga, H. Baba, S. Franchoo, H. Nishibata 他
  • Journal Title: Phys. Rev. Lett. Volume: 113 Issue: 3 Pages: 032505-032505
  • DOI: 10.1103/physrevlett.113.032505
  • Peer Reviewed / Open Access
• [Journal Article] Intermediate-energy Coulomb excitation of 104Sn: Moderate E2 strength decrease approaching 100Sn (2014)
  • Author(s): P. Doornenbal, et. al.
  • Journal Title: Physical Review C Volume: 90 Issue: 6 Pages: 061302-061302
  • DOI: 10.1103/physrevc.90.061302
  • Peer Reviewed
• [Journal Article] Evidence for a new ‘magic number’ in 54Ca (2014)
  • Author(s): D. Steppenbeck, et. al.
  • Journal Title: RIKEN Accelerator Progress Report Volume: 47
  • Peer Reviewed / Open Access
• [Journal Article] Decay spectroscopy around 78Ni with the EURICA setup (2014)
  • Author(s): G. Benzoni, et. al.
  • Journal Title: RIKEN Accelerator Progress Report Volume: 47 Pages: 8-8
  • Peer Reviewed / Open Access
• [Journal Article] Intermediate energy Coulomb excitation of 73, 74, 75Ni (2014)
  • Author(s): A. Gottardo, et. al.
  • Journal Title: RIKEN Accelerator Progress Report Volume: 47 Pages: 36-36
  • Peer Reviewed / Open Access
• [Presentation] First spectroscopy of the Doubly-Magic 78Ni (2017)
  • Author(s): R. Taniuchi
  • Organizer: 日本物理学会 第72回年次大会
  • Place of Presentation: 大阪大学豊中キャンパス（大阪府豊中市）
  • Year and Date: 2017-03-18
• [Presentation] First spectroscopy of the Doubly-Magic 78Ni (2016)
  • Author(s): R. Taniuchi
  • Organizer: Sunflower workshop
  • Place of Presentation: HongKong, China
  • Year and Date: 2016-09-19
  • Int'l Joint Research
• [Presentation] First spectroscopy of the Doubly-Magic 78Ni (2016)
  • Author(s): R. Taniuchi
  • Organizer: INPC2016
  • Place of Presentation: Adelaide, Australia
  • Year and Date: 2016-09-13
  • Int'l Joint Research
• [Presentation] Examining Signal Decomposition in Ge Tracking Detectors through Source-Based Coincidence Measurements (2016)
  • Author(s): M. Cromaz, et. al.,
  • Organizer: APS April Meeting 2016
  • Place of Presentation: Salt Lake City, Utah, USA
  • Year and Date: 2016-04-18
  • Int'l Joint Research
• [Presentation] In-beam gamma-ray spectroscopy of 78Ni (2015)
  • Author(s): R. Taniuchi
  • Organizer: Gamma15
  • Place of Presentation: 大阪大学豊中キャンパス（大阪府豊中市）
  • Year and Date: 2015-10-01
  • Int'l Joint Research
• [Presentation] In-beam gamma-ray spectroscopy of 78Ni (2015)
  • Author(s): R. Taniuchi
  • Organizer: Nuclear Structure and Dynamics III
  • Place of Presentation: Portroz, Slovenia
  • Year and Date: 2015-06-19
  • Int'l Joint Research
• [Presentation] 78Niのインビームガンマ線核分光 (2015)
  • Author(s): R. Taniuchi, et. al.
  • Organizer: 日本物理学会 第70回年次大会
  • Place of Presentation: 早稲田大学
  • Year and Date: 2015-03-21
• [Presentation] DALI2 calibration, timing, efficiency and simulations (2015)
  • Author(s): R. Taniuchi
  • Organizer: SEASTAR Analysis Workshop
  • Place of Presentation: Paris, France
  • Year and Date: 2015-03-10
• [Presentation] Status report of the SEASTAR experiment: DALI calibration for 78Ni excited states (2014)
  • Author(s): R. Taniuchi
  • Organizer: 3rd SUNFLOWER Workshop
  • Place of Presentation: 東京大学
  • Year and Date: 2014-09-15
• [Presentation] Development of a next-generation detector for in-beam γ-ray spectroscopy on exotic nuclei (2014)
  • Author(s): R. Taniuchi, H. Sakurai, P. Doornenbal, N. Kobayashi, K. Matsui, T. Miyazaki, S. Momiyama, M. Niikura, and Z.Y. Xu
  • Organizer: Advances in Radioactive Isotope Science 2014
  • Place of Presentation: 東京大学
  • Year and Date: 2014-06-05
• [Remarks] 櫻井研究室
  • URL: http://nucl.phys.s.u-tokyo.ac.jp/sakurai_g/
• [Remarks] 仁科加速器研究センター
  • URL: http://www.nishina.riken.jp/index.html