Elucidation of the rare-earth element peak around A = 160 in the r-process nucleosynthesis

• Project/Area Number: 24740188
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: The Institute of Physical and Chemical Research
• Principal Investigator: WATANABE Hiroshi 独立行政法人理化学研究所, 仁科加速器研究センター, 客員研究員 (60333316)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Project Status: Completed (Fiscal Year 2014)
• Budget Amount: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000); Fiscal Year 2013: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2012: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
• Keywords: 国際共同研究 / 元素合成 / 中性子過剰核 / ベータ崩壊 / 半減期 / 核異性体 / RIビームファクトリー / アイソマー / 加速器

Outline of Final Research Achievements

Nearly half of elements heavier than iron in the universe are considered to be synthesized via a rapid-neutron capture (r) process, which takes place in explosive astrophysical sites like supernovae and/or neutron-star mergers. In the present work, we have measured beta-decay half-lives, decay schemes, and isomeric states in a wide range of neutron-rich isotopes relevant to the r-process nucleosynthesis, particularly focusing on deformed nuclei around mass 160 which should affect the formation of the so-called rare-earth element peak. Those spectroscopic information, in combination with the new data obtained as well for neutron-rich isotopes in the vicinity of the doubly-magic nuclei 78Ni and 132Sn, are expected to serve for improvement of the astrophysical simulations of r-process.

Research Products

• [Journal Article] Monopole-Driven Shell Evolution below the Doubly Magic Nucleus 132Sn Explored with the Long-Lived Isomer in 126Pd (2014)
  • Author(s): H. Watanabe, G. Lorusso, S. Nishimura, T. Otsuka, K. Ogawa, Z.Y. Xu, T. Sumikama, P.-A. Soderstrom, P. Doornenbal, Z. Li, F. Browne, G. Gey, H.S. Jung, J. Taprogge, Zs. Vajta, J. Wu, A. Yagi, H. Baba, G. Benzoni, H. Nishibata 他
  • Journal Title: Phys. Rev. Lett. Volume: 113 Issue: 4 Pages: 042502-042502
  • DOI: 10.1103/physrevlett.113.042502
  • Peer Reviewed / Open Access
• [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] 1p3/2 Proton-Hole State in 132Sn and the Shell Structure Along N= 82 (2014)
  • Author(s): J. Taprogge, A. Jungclaus, H. Grawe, S. Nishimura, P. Doornenbal, G. Lorusso, G.S. Simpson, P.-A. Soderstrom, T. Sumikama, Z.Y. Xu, H. Baba, F. Browne, N. Fukuda, R. Gernhauser, G. Gey, N. Inabe, T. Isobe, H.S. Jung, D. Kameda, H. Nishibata 他
  • Journal Title: Phys. Rev. Lett. Volume: 112 Issue: 13 Pages: 132501-132501
  • DOI: 10.1103/physrevlett.112.132501
  • Peer Reviewed / Open Access
• [Journal Article] Identification of a millisecond isomeric state in 129Cd81 via the detection of internal conversion and Compton electrons (2014)
  • Author(s): J. Taprogge, A. Jungclaus, H. Grawe, S. Nishimura, Z.Y. Xu, P. Doornenbal, G. Lorusso, E. Nacher, G.S. Simpson, P.-A. Soderstrom, T. Sumikama, H. Baba, F. Browne, N. Fukuda, R. Gernhauser, G. Gey, N. Inabe, T. Isobe, H.S. Jung, H. Nishibata 他
  • Journal Title: Phys. Lett. B Volume: 738 Pages: 223-227
  • DOI: 10.1016/j.physletb.2014.09.047
  • Peer Reviewed / Open Access
• [Journal Article] Yrast 6+ Seniority Isomers of 136, 138Sn (2014)
  • Author(s): G.S. Simpson, G. Gey, A. Jungclaus, J. Taprogge, S. Nishimura, K. Sieja, P. Doornenbal, G. Lorusso, P.-A. Soderstrom, T. Sumikama, Z.Y. Xu, H. Baba, F. Browne, N. Fukuda, N. Inabe, T. Isobe, H.S. Jung, D. Kameda, G.D. Kim, H. Nishibata 他
  • Journal Title: Phys. Rev. Lett. Volume: 113 Issue: 13 Pages: 132502-132502
  • DOI: 10.1103/physrevlett.113.132502
  • Peer Reviewed / Open Access
• [Journal Article] Isomer Decay Spectroscopy of 164Sm and 166Gd: Midshell Collectivity Around N=100 (2014)
  • Author(s): Z. Patel, P.-A. Soderstrom, Zs. Podolyak, P.H. Regan, P.M. Walker, H. Watanabe, E. Ideguchi, G.S. Simpson, H.L. Liu, S. Nishimura, Q. Wu, F.R. Xu, F. Browne, P. Doornenbal, G. Lorusso, S. Rice, L. Sinclair, T. Sumikama, J. Wu, H. Nishibata 他
  • Journal Title: Phys. Rev. Lett. Volume: 113 Issue: 26 Pages: 262502-262502
  • DOI: 10.1103/physrevlett.113.262502
  • Peer Reviewed
• [Journal Article] Isomers in ^<128>Pd and ^<126>Pd : Evidence for a Robust Shell Closure at the Neutron Magic Number 82 in Exotic Palladium Isotopes (2013)
  • Author(s): H. Watanabe, 他
  • Journal Title: Physical Review Letters Volume: 111 Issue: 15 Pages: 152501-152501
  • DOI: 10.1103/physrevlett.111.152501
  • Peer Reviewed
• [Journal Article] Spectroscopy of 135La (2013)
  • Author(s): R. Leguillon, H. Nishibata, Y. Ito, C.M. Petrache, H. Watanabe, et al.
  • Journal Title: Physical Review C Volume: 88 Issue: 4 Pages: 44309-44309
  • DOI: 10.1103/physrevc.88.044309
  • Peer Reviewed
• [Journal Article] Multiquasiparticle states in the neutron-rich nucleus 174Tm (2013)
  • Author(s): R.O. Hughes, G.J. Lane, G.D. Dracoulis, A.P. Byrne, H. Watanabe, et al.
  • Journal Title: Physical Review C Volume: 88 Issue: 1 Pages: 14311-14311
  • DOI: 10.1103/physrevc.88.014311
  • Peer Reviewed
• [Journal Article] Novel method for the production of spin-aligned RI beams in projectile fragmentation reaction with the dispersion matching technique (2013)
  • Author(s): Y. Ichikawa, H. Ueno, Y. Ishii, T. Furukawa, A. Yoshimi, D. Kameda, H. Watanabe, N. Aoi, K. Asahi, D. L. Balabanski, R. Chevrier, J. M. Daugas, N. Fukuda, G. Georgiev, H. Hayashi, H. Iijima, N. Inabe, T. Inoue, M. Ishihara, T. Kubo, T. Nanao, T. Ohnishi, K. Suzuki, M. Tsuchiya, H. Takeda, M. M. Rajabali
  • Journal Title: Hyperfine Interactions Volume: 220 Issue: 1-3 Pages: 47-51
  • DOI: 10.1007/s10751-012-0682-8
  • Peer Reviewed
• [Journal Article] Shell evolution in ^<116,118>Ru : Triaxiality and transition between the O (6) and U (5) dynamical symmetries (2013)
  • Author(s): P. -A. Sӧderstrӧm, 他
  • Journal Title: Physical Review C Volume: 88 Issue: 2 Pages: 24301-24301
  • DOI: 10.1103/physrevc.88.024301
  • Peer Reviewed
• [Journal Article] Isomers and excitation modes in the gamma-soft nucleus 192Os (2013)
  • Author(s): G.D.Dracoulis, G.J.Lane, A.P.Byrne, H.Watanabe, et al.
  • Journal Title: Physics Letters B Volume: 720 Issue: 4-5 Pages: 330-335
  • DOI: 10.1016/j.physletb.2013.02.026
  • Peer Reviewed
• [Journal Article] Three-quasiparticle isomers and possible deformation in the transitional nuclide, 195Au (2013)
  • Author(s): G.D.Dracoulis, G.J.Lane, H.Watanabe, et al.
  • Journal Title: Physical Review C Volume: 87 Issue: 1 Pages: 14326-14326
  • DOI: 10.1103/physrevc.87.014326
  • Peer Reviewed
• [Journal Article] Prolate-Oblate Shape Coexistence and Enhanced gamma Softness in Neutron-Rich Nb and Mo Isotopes with A～110 (2012)
  • Author(s): Hiroshi Watanabe
  • Journal Title: Progress of Theoretical Physics, Supplements Volume: 196 Pages: 145-149
  • DOI: 10.1143/ptps.196.145
  • NAID: 110009543665
  • Peer Reviewed
• [Journal Article] Long-lived three-quasiparticle isomers in 191Ir and 193Ir with triaxial deformation (2012)
  • Author(s): G.D.Dracoulis, G.J.Lane, A.P.Byrne, H.Watanabe, et al.
  • Journal Title: Physics Letters B Volume: 709 Issue: 1-2 Pages: 59-64
  • DOI: 10.1016/j.physletb.2012.02.008
  • Peer Reviewed
• [Presentation] Decay spectroscopy at RIBF (2015)
  • Author(s): Hiroshi Watanabe
  • 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 – 2015-03-24
  • Invited
• [Presentation] Highlights of EURICA decay spectroscopy at RIBF (2014)
  • Author(s): Hiroshi Watanabe
  • Organizer: Fourth Joint Meeting of the Nuclear Physics Divisions of the American Physical Society and The Physical Society of Japan (HAWAII2014)
  • Place of Presentation: Hawaii, USA
  • Year and Date: 2014-10-07 – 2014-10-11
  • Invited
• [Presentation] Gamma-ray spectroscopy of exotic nuclei with EURICA (2014)
  • Author(s): Hiroshi Watanabe
  • Organizer: International Symposium on EXOtic Nuclei (EXON-2014)
  • Place of Presentation: Kaliningrad, Russia
  • Year and Date: 2014-09-08 – 2014-09-13
  • Invited
• [Presentation] The nature of a shell closure at N=82 explored with seniority and spin-gap isomers in neutron-rich Pd and Ag isotopes (2014)
  • Author(s): Hiroshi Watanabe
  • Organizer: Advances in Radioactive Isotope Science (ARIS2014)
  • Place of Presentation: 東京大学
  • Year and Date: 2014-06-01 – 2014-06-06
• [Presentation] Decay spectroscopy with EURICA at RIBF: Exploring new aspects far from stability (2014)
  • Author(s): 渡邉寛
  • Organizer: 2nd Topical Workshop on Modern Aspects in Nuclear Structure
  • Place of Presentation: Bormio, Italy
  • Invited
• [Presentation] Isomers and the N=82 magicity in neutron-rich 46Pd and 47Ag isotopes (2013)
  • Author(s): 渡邉寛
  • Organizer: JUSTIPEN-JUSEIPEN Workshop
  • Place of Presentation: 理化学研究所和光キャンパス
• [Presentation] Shape transitions and isomers in neutron-rich Pd isotopes (2013)
  • Author(s): 渡邉寛
  • Organizer: PKU-CUSTIPEN mini-symposium on “Dynamics of nuclear decays and related topics”
  • Place of Presentation: Peking University, China
  • Invited
• [Presentation] Recent results of decay spectroscopy at RIBF (2013)
  • Author(s): 渡邉寛
  • Organizer: Heavy Ion Accelerator Symposium on Fundamental and Applied Science
  • Place of Presentation: Australian National University, Canberra, Australia
• [Presentation] Recent results of decay spectroscopy at RIBF and future perspectives with EURICA (2012)
  • Author(s): 渡邉寛
  • Organizer: 8th Tours Symposium On Nuclear Physics and Astrophysics (TOURS2012)
  • Place of Presentation: Black Forest, Lenzkirch-Saig, Germany
  • Invited
• [Remarks] Neutron holes achieve metastable status
  • URL: http://www.riken.jp/en/research/rikenresearch/highlights/7866/