Beta-decay of very neutron-rich nuclei relevant to nucleosynthesis

• Project/Area Number: 19340074
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: The Institute of Physical and Chemical Research
• Principal Investigator: NISHIMURA Shunji The Institute of Physical and Chemical Research, 櫻井RI物理研究室, 先任研究員 (90272137)
• Project Period (FY): 2007 – 2010
• Project Status: Completed (Fiscal Year 2010)
• Budget Amount: ¥18,460,000 (Direct Cost: ¥14,200,000、Indirect Cost: ¥4,260,000); Fiscal Year 2010: ¥520,000 (Direct Cost: ¥400,000、Indirect Cost: ¥120,000); Fiscal Year 2009: ¥10,010,000 (Direct Cost: ¥7,700,000、Indirect Cost: ¥2,310,000); Fiscal Year 2008: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000); Fiscal Year 2007: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
• Keywords: 元素合成 / ベータ崩壊 / 半減期 / 不安定核 / 超新星爆発 / r過程 / β崩壊 / 中性子過剰核 / R過程 / R-過程 / 半減期測定 / beta-decay / Nuclear Structure / Astrophysics / Unstable nuclei

Research Abstract

The beta-decay half-lives of 38 neutron-rich isotopes (18 for first time) from Kr to Tc, which play important role in the r-process nucleosynthesis, have been measured. The results when compared with previous standard models indicate the overestimation in the predicted half-lives by a factor of 2 or more in the A～110 region. The results suggest a more rapid flow of the rapid neutron capture process (r-matter flow) through this region around mass A=110～125 than previously predicted.

Research Products

• [Journal Article] β-Decay Half-lives of Very Neutron-Rich Kr to Tc Isotopes on the Boundary of the r-Process Path : An Indication of Fast r-Matter Flow (2011)
  • Author(s): S.Nishimura, et al.
  • Journal Title: Physical Review Letters 106
  • Peer Reviewed
• [Journal Article] Structural Evolution in the Neutron-Rich Nuclei 106Zr and 108Zr (2011)
  • Author(s): T.Sumikama, K.Yoshinaga, H.Watanabe, S.Nishimura, et al.
  • Journal Title: Physical Review Letters 106
  • Peer Reviewed
• [Journal Article] Low-lying level structure of the neutron-rich nucleus 109Nb : A possible oblate-shape isomer (2011)
  • Author(s): H.Watanabe, T.Sumikama, S.Nishimura, et al.
  • Journal Title: Physics Letters B 696 Pages: 186-190
  • Peer Reviewed
• [Journal Article] β-Decay Half-Lives of Very Neutron-Rich Kr to Tc Isotopes on the Boundary of the r-Process Path : An Indication of Fast r-Matter Flow (2011)
  • Author(s): S.Nishimura, et al.
  • Journal Title: Phys.Rev.Lett. Volume: 106
  • Peer Reviewed
• [Journal Article] Low-Lying level structure of the neutron-rich nucleus ^<109>Nb : A possible oblate-shape isomer (2011)
  • Author(s): H.Watanabe, et al.
  • Journal Title: Phys.Lett.B Volume: 696 Pages: 186-190
  • Peer Reviewed
• [Journal Article] First Decay Experiment at RIBF (2010)
  • Author(s): S.Nishimura
  • Journal Title: AIP Conf.Proc. 1269 Pages: 91-97
  • Peer Reviewed
• [Journal Article] Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon (2010)
  • Author(s): T.Ohnishi, et al.
  • Journal Title: Jounal of the Physical Society of Japan 79
  • Peer Reviewed
• [Journal Article] First Decay Spectroscopy Experiment at RIBF (2010)
  • Author(s): S.Nishimura
  • Journal Title: AIP Conference Proceedings (OMEG 10) Volume: 1269 Pages: 91-97
  • Peer Reviewed
• [Journal Article] π-/π+Ratio Observed in the Central Collisions of 115In+132Xe Reaction at 400A MeV (2010)
  • Author(s): T. Murakami, et al., (13名, 9番目)
  • Journal Title: Nucl.Phys.A 834
  • Peer Reviewed
• [Journal Article] Beta-counting systems for decay spectroscopy projects (2009)
  • Author(s): S.Nishimura, et al.
  • Journal Title: RIEKN Accel.Prog.Rep. 42 Pages: 183-183
  • Peer Reviewed
• [Journal Article] Spectroscopy of 32Ne and the Island of Inversion (2009)
  • Author(s): P.Doornenbal, et al.
  • Journal Title: Physical Review Letters 103
  • Peer Reviewed
• [Journal Article] Investigation of excited states in 32Mg via resonant scattering of 21Na + p and its astrophysical implications (2009)
  • Author(s): J.J.He, et al.
  • Journal Title: Physical Review C 80
  • Peer Reviewed
• [Journal Article] Low-lying non-normal parity states in ^8B measured by proton elastic scattering on 7Be (2009)
  • Author(s): H.Yamaguchi, et al.
  • Journal Title: Phys.Lett.B 672 Pages: 230-234
  • Peer Reviewed
• [Journal Article] Beta-counting systems for decay spectroscopy projects (2009)
  • Author(s): S. Nishimura, et al.
  • Journal Title: RIEKN Accel.Prog.Rep. 42 Pages: 183-183
  • Peer Reviewed
• [Journal Article] Low-lying non-normal parity states in 8B measured by proton elastic scattering on 7Be (2009)
  • Author(s): H. Yamaguchi, et al., (15名, 9番目)
  • Journal Title: Phys.Lett.B 672 Pages: 230-234
  • Peer Reviewed
• [Journal Article] Spectroscopy of ^<32>Ne and the "Island of Inversion" (2009)
  • Author(s): P.Doornenbal, et al.
  • Journal Title: Physical Review Letters 103
  • Peer Reviewed
• [Journal Article] Investigation of excited states in ^<22>Mg via resonant scattering of ^<21>Na+p and its astrophysical implications (2009)
  • Author(s): J.J.He, et al.
  • Journal Title: Physical Review C 80
  • Peer Reviewed
• [Journal Article] Beta-counting systems for decay-spectroscopy projects (2009)
  • Author(s): S.Nishimura, et al.
  • Journal Title: RIKEN Accel.Prog.Rep. 42 Pages: 183-183
  • Peer Reviewed
• [Journal Article] Low-lying non-normal parity states in ^8B measured by proton elastic scattering on ^7Be (2009)
  • Author(s): H. Yamaguchi, et al.
  • Journal Title: Phys. Lett. B 672 Pages: 230-234
  • Peer Reviewed
• [Journal Article] Experimental Approach to Explosive Nucloeosynthesis with RI Beams (2009)
  • Author(s): S. Kubono, et al.
  • Journal Title: Journal of the Korean Physics Society 54 Pages: 308-312
  • Peer Reviewed
• [Journal Article] Development of a super-segmented beta-counting system CAITEN (2008)
  • Author(s): S.Nishimura, et al
  • Journal Title: RIKEN Accel.Prog.Rep. 41 Pages: 149-149
  • Peer Reviewed
• [Journal Article] Development of wide-dynamic range readout system of silicon detector from 20keV to 4GeV (2008)
  • Author(s): N.Uematsu, S.Nishimura
  • Journal Title: RIKEN Accel.Prog.Rep. 41 Pages: 151-151
  • Peer Reviewed
• [Journal Article] Suppression of High-pt Neutral Pion Production in Central Pb+Pb Collisions at √<S_<NN>>=17.3GeV Relative to p+C and p+Pb Collisions (2008)
  • Author(s): M. M. Aggarwal, et al
  • Journal Title: Phys. Rev. Lett. 100
  • Peer Reviewed
• [Journal Article] Development of a super-segmented beta-counting system CAITEN (2008)
  • Author(s): S. Nishimura
  • Journal Title: RIKEN Accel. Prog. Rep. 41 41 Pages: 149-149
  • Peer Reviewed
• [Journal Article] Development of silicon-strip detector with wide-dynamic-range readout system from 20keV to 4GeV (2008)
  • Author(s): N. Uematsu, S. Nishimura
  • Journal Title: RIKEN Accel. Prog. Rep. 41 Pages: 151-152
  • Peer Reviewed
• [Journal Article] Development of ^<46>Cr secondary beam (2008)
  • Author(s): Y. Wakabayashi, et al.
  • Journal Title: RIKEN Accel. Prog. Rep. 41 Pages: 25-25
  • Peer Reviewed
• [Journal Article] Investigate of struture in <23>^Al via resonant proton scattering of<22>^Mg(p,γ)^<23>Al astrophysical reaction rate (2007)
  • Author(s): J.J.He, et. al.
  • Journal Title: Physical review C 76
  • Peer Reviewed
• [Journal Article] Single-particle resonanace levels in 140 examined by 13N + p elastic scattering (2007)
  • Author(s): T.Teranishi, et. al.
  • Journal Title: Physic Letters B 650 Pages: 129-134
  • Peer Reviewed
• [Journal Article] Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon
  • Author(s): T. Ohnishi, et al., (6名, 20番目)
  • Journal Title: JPSJ submitted
  • Peer Reviewed
• [Presentation] Measurement of Beta Decay Rates for the r-Process (2011)
  • Author(s): 西村俊二
  • Organizer: ECT*「The Origin of the Elements : A Modern Perspective」
  • Place of Presentation: Italy, Trento(Invited)
• [Presentation] First Decay Experiment at RIBF (2010)
  • Author(s): 西村俊二
  • Organizer: OMEG10
  • Place of Presentation: OSaka(Invited)
  • Year and Date: 2010-03-08
• [Presentation] First Decay Experiment at RIBF (2010)
  • Author(s): 西村俊二, 代表
  • Organizer: OMEG10
  • Place of Presentation: 大阪大学・吹田キャンパス
  • Year and Date: 2010-03-08
• [Presentation] First decay experiment at the RIBF (2010)
  • Author(s): Shunji Nishimura
  • Organizer: The 10^<th> International Symposium on Origin of M Matterr and Evolution of the Galaxies(OMEG10)
  • Place of Presentation: Suits Campus, Osaka University
  • Year and Date: 2010-03-08
• [Presentation] First Decay Experiment at the RIBF (2010)
  • Author(s): 西村俊二
  • Organizer: ICHOR-EFES International Symposium on New Facet of Spin-Isospin Responses (SIR2010)
  • Place of Presentation: 東京大学・本郷キャンパス(Invited)
  • Year and Date: 2010-02-19
• [Presentation] First Decay Experiment at the RIBF (2010)
  • Author(s): 西村俊二, 代表
  • Organizer: CHOR-EFES International Symposium on New Facet of Spin-Isospin Responses (SIR2010)
  • Place of Presentation: 東京大学・本郷キャンパス
  • Year and Date: 2010-02-19
• [Presentation] First decay experiment at the RIBF (2010)
  • Author(s): Shunji Nishimura
  • Organizer: ICHOR-EFES International Symposium on New Facet of Spin-Isospin Responses(SIR2010)
  • Place of Presentation: Koshiba-Hall, University of Tokyo
  • Year and Date: 2010-02-19
• [Presentation] First Decay Spectroscopy at RIBF (2010)
  • Author(s): 西村俊二
  • Organizer: Nuclear Structure 2010
  • Place of Presentation: USA, Berkeley(Invited)
• [Presentation] First results from RIBF and the scope (2009)
  • Author(s): 西村俊二
  • Organizer: 3^<rd> Joint Meeting of Nuclear Physics Divisions of the APS and the JPS
  • Place of Presentation: USA・Hawaii
  • Year and Date: 2009-10-13
• [Presentation] First results from RIBF and the scope (2009)
  • Author(s): 西村俊二, 代表
  • Organizer: 3^<rd> Joint Meeting of Nuclear Physics Divisions of the APS and the JPS
  • Place of Presentation: 米国・ハワイ島
  • Year and Date: 2009-10-13
• [Presentation] First results from the RIBF and the scope (2009)
  • Author(s): Shunji Nishimura
  • Organizer: Workshop on Frontiers in Nuclear Atrophysics I
  • Place of Presentation: Hawaii(USA)
  • Year and Date: 2009-10-13
• [Presentation] Decay spectroscopy experiments and spin-isospin (2008)
  • Author(s): 西村俊二
  • Organizer: ICHOR-EFES International Symposium on New Facet of Spin-Isospin Responses (SIR2008)
  • Place of Presentation: Saitama, Japan(Invited)
  • Year and Date: 2008-10-30
• [Presentation] Decay spectroscopy experiments and spin-isospin (2008)
  • Author(s): 西村俊二, 代表
  • Organizer: ICHOR-EFES International Symposium on New Facet of Spin-Isospin Responses (SIR2008)
  • Place of Presentation: 埼玉県・和光市・理化学研究所
  • Year and Date: 2008-10-30
• [Presentation] Decay Spectroscopy and Spin-Isospin (2008)
  • Author(s): S. Nishimura
  • Organizer: ICHOR=EFES International Symposium on New Facet of Spin-Isospin Responses-Toward the Commissioning of SHARAQ Spectrometer (SIR2008)
  • Place of Presentation: 理化学研究所
  • Year and Date: 2008-10-30
• [Presentation] 回転式シンチレーション検出器を用いた半減期測定装置の開発 (2008)
  • Author(s): 西村俊二
  • Organizer: 日本物理学会
  • Place of Presentation: 近畿大学
  • Year and Date: 2008-03-24
• [Presentation] Decay Spectroscopy experiments at the RIBF (2007)
  • Author(s): 西村 俊二
  • Organizer: 3^<rd> Japanese-German workshop on Nuclear Structure and Astrophysics
  • Place of Presentation: ドイツ・Frauenworth im Chiemsee
  • Year and Date: 2007-10-01
• [Presentation] Beta decay study of neutron-rich nuclei at the RIBF (2007)
  • Author(s): 西村 俊二
  • Organizer: 日本物理学会
  • Place of Presentation: 北海道大学
  • Year and Date: 2007-09-21