• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to project page

1998 Fiscal Year Final Research Report Summary

Nuclear astrophysics studied by neutrons

Research Project

Project/Area Number 08102004
Research Category

Grant-in-Aid for Specially Promoted Research

Allocation TypeSingle-year Grants
Review Section Physics
Research InstitutionTokyo Institute of Technology

Principal Investigator

NAGAI Yasuki  Tokyo Institute of Technology, Department of Physics, Professor (80028240)

Co-Investigator(Kenkyū-buntansha) SHIMA Tatsushi  Tokyo Institute of Technology, Department of Physics, Research Associate (10222035)
Project Period (FY) 1996 – 1998
Keywordsnuclear astrophysics / stellar evolution / stellar nucleosynthesis / primordial nucleosynthesis / neutron capture reaction / p-wave neutron / prompt γ-ray detection method / NaI(T1)detector
Research Abstract

Recently a lot of efforts are being made to observe an abundance of heavy elements in ultra metal deficient stars to obtain information of stellar nucleosynthesis in the early history of Galaxy. In order to reveal the history of Galaxy it is crucial to construct solid models of stellar evolution and stellar nucleosynthesis these ultra metal deficient stars. These stars are characterized to have very few iron seed light nuclei such as C, O and Ne etc. Hence, these nuclei would act as a neutron poison and would strongly reduce the production yields of heavy elements, if the neutron capture cross section of the nuclei would be large. Therefore, it is necessary to measure the neutron capture (n, γ) cross section of these light nuclei at astrophysically relevant energy to construct the models mentioned above.
In the present work we aimed at accurately measuring the (n, γ) cross section of ^<6,7>Li, ^<13>C,^<16,18>O and ^<20,22>Ne, which have not been well studied. The measurement has been ca … More rried out successfully by significantly improving the signal to noise ration and the γ・ray detection efficiency of the existing anti-Compton NaI(Tl) spectrometer, and by newly constructing the liquefier for gaseous Ne sample. Actually we could improve the signal to noise ration by a factor 4 and the γ-ray efficiency by a factor 2. The measured cross sections of ^7Li,^<13>C, ^<16,18>O and ^<20,22>Ne clearly indicate that these nuclei act as a neutron poison in ultra metal deficient stars.
Concerning the primordial D problem we measured the D(n, γ) T reaction cross section. The reaction is quite important, since it is a mirror reaction of the D(n, γ)^3He reaction, which destroys the primordial D. Our result would be quite useful to derive the S-factor of the D(p, γ)^3He reaction free from a Coulomb effect. As for the ^6Li(n, γ)^7Li reaction, our result clearly indicates that the excitation function does not follow the curve expected from a l/v law, although the reaction proceeds via an s-wave neutron capture. These could suggest that the s_<1/2> particle state in the cotinuum state, which has not yet been identified, is responsible for the energy dependence of the cross section. Concerning the ^7Li(n, γ)^8Li reaction we have for the first time measured the γ-ray branching ratio from the neutron capturing state to the ground and first excited states using an anti Compton HpGe spectrometer. The result gives a vital information to determine to S_<17> factor for the ^7Be(p, γ)^8B reaction. Finally we have also measured successfully the absolute keV neutron flux at KENS and the result indicates that the use of spallation neutrons for nuclear astrophysics is promising. Less

  • Research Products

    (40 results)

All 2002 1999 1998 1997 1996 1995 Other

All Journal Article (39 results) Patent(Industrial Property Rights) (1 results)

  • [Journal Article] Neutron reactions of light nuclei from astrophysics & nuclear physics interest2002

    • Author(s)
      Y. Nagai
    • Journal Title

      Astrophysics, Symmetries, and Appliee Physics at Spallation Neutron Sources, ed. by P. E. Koehler, C. R. Gould, R. C. Haight

      Pages: 52-57

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Critical role of(n, γ)reaction of light nuclei in nuclear astrophysics2002

    • Author(s)
      Y. Nagai
    • Journal Title

      11th Int. Symp. on Capture γ-Ray Spectroscopy and Related Topics

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Measurement of the p(n, γ)d reaction cross section between En = 100 and 350 keVv2002

    • Author(s)
      Y. Nagai
    • Journal Title

      Proc. 7th Int. Symp. on Nuclei in the Cosmos, Fuji-Yoshida

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Neutron capture cross section measurement of 20, 22Ne for stellar nucleosynthesis2002

    • Author(s)
      A. Tomyo
    • Journal Title

      Proc. 7th Int. Symp. on Nuclei in the Cosmos, Fuji-Yoshida

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] 84Kr(n, γ)85Kr reaction cross section measured by an NaI(Tl)spectrometer between 10 and 80 keV2002

    • Author(s)
      A. Tomyo
    • Journal Title

      Proc. 7th Int. Symp. on Nuclei in the Cosmos, Fuii-Yoshida

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Stellar neutron capture cross sections of 128, 129, 130Xe2002

    • Author(s)
      R. Reifarth
    • Journal Title

      Phys. Rev. C66

      Pages: 064603-1-064603-14

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Y. Nagai, Neutron reactions of light nuclei from astrophysics & nuclear physics interest2002

    • Author(s)
      Y. Nagai
    • Journal Title

      Astrophysics, Symmetries, and Applied Physics at Spallation Neutron Sources, ed. by P. E. Koehler, C. R. Gould, R. C. Haight

      Pages: 52-57

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Critical role of(n, γ)reaction of light nuclei in nuclear astrophysics2002

    • Author(s)
      Y. Nagai
    • Journal Title

      11th Int. Symp. on Capture γ- Ray Spectroscopy and Related Topics

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Measurement of the p(n, γ)d reaction cross section between En = 100 and 350 keVy2002

    • Author(s)
      Y. Nagai
    • Journal Title

      Proc. 7th Int. Symp. on Nuclei in the Cosmos, Fuji-Yoshida

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] 84Kr(n, γ)85Kr reaction cross section measured by an NaI(Tl)spectrometer between 10 and 80 keV2002

    • Author(s)
      A. Tomyo
    • Journal Title

      Proc. 7th Int. Symp. on Nuclei in the Cosmos, Fuji-Yoshida

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] KENS keV neutron flux for nuclear astrophysics1999

    • Author(s)
      S. saito
    • Journal Title

      Nucl. Instr. Meth. A428

      Pages: 404-413

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] An NaI(Tl)spectrometer system for ke V neutron radiative-capture reactions1999

    • Author(s)
      T. Ohsaki
    • Journal Title

      Nucl. Instr. Meth. A425

      Pages: 302-319

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Cross section of the 14N(n, p)14C reaction from 10 to 100 keV measured by a gas scintillation drift chamber1999

    • Author(s)
      T. Kii
    • Journal Title

      Phys. Rev. C 59

      Pages: 3397-3401

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] A liquefier system for keV neutron radiative capture reaction of a gaseous ample1999

    • Author(s)
      Y. Nobuhara
    • Journal Title

      Nucl. Instr. Meth. A437

      Pages: 508-515

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] First measurement of neutrons capture cross section of 6Li at stellar energy1999

    • Author(s)
      T. Ohsaki
    • Journal Title

      Proc. Int. Symp capture γ-Ray Spectroscopy and Related Topics Aug

      Pages: 678-680

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] keV neutron capture cross sections of light nuclei and nucleosynthesis1999

    • Author(s)
      T. Ohsaki
    • Journal Title

      Proc Int. Symp Capture γ-Ray Spectroscopy and Related Topics Aug.

      Pages: 458-465

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] KENS keV neutron flux for nuclear astrophysics1999

    • Author(s)
      S. Saito
    • Journal Title

      Nucl. Instr. Meth. A423

      Pages: 404-413

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Cross section of the 14N(n, p)14C reaction from 10 to 100 keV measured by a gas scintillation driftchamber1999

    • Author(s)
      T. Kii
    • Journal Title

      Phys. Rev. C 59

      Pages: 3397-3401

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] A liquefier system for keV neutron radiative capture reactions of a gaseous ample1999

    • Author(s)
      Y. Nobuhara
    • Journal Title

      Nucl. Instr. Meth. A437

      Pages: 508-515

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] First measurement of neutron capture cross section of 6Li at stellar energy1999

    • Author(s)
      T. Ohsaki
    • Journal Title

      Proc. Int. Symp. Capture γ- Ray Spectroscopy and Related topics Aug.

      Pages: 678-680

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] keV neutron capture cross sections of light nuclei and nucleosynthesis1999

    • Author(s)
      T. Ohsaki
    • Journal Title

      Proc. Int. Symp. Capture γ- Ray Spectroscopy and Related topics Aug.

      Pages: 458-465

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Nuclea and nuclear astrophysical interest in D(n, γ)3H reaction1998

    • Author(s)
      Y. Nagai
    • Journal Title

      Nucl. Instr. Meth. A402

      Pages: 408-411

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Nonresonant, direct p-and d-wave neutron capture by 12C1998

    • Author(s)
      T. Kikuchi
    • Journal Title

      Phys Rev. C 57

      Pages: 2724-273

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Nuclear and nuclear astrophysical interest in D(n, γ)3H reaction1998

    • Author(s)
      Y. Nagai
    • Journal Title

      Nucl. Instr. Meth. A402

      Pages: 408-411

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Nonresonant direct p- and d-wave neutron capture by 12C1998

    • Author(s)
      T. Kikuchi
    • Journal Title

      Phys. Rev. C 57

      Pages: 2724-2730

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Measurement of the 13C(n, γ)14C cross secton at stellar energies1997

    • Author(s)
      T. Shima
    • Journal Title

      Nucl. Phy. A621

      Pages: 231c-234c

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Measurement of the 1H(n, γ)2H reaction cross section at a comparable M1/E1 strength1997

    • Author(s)
      Y. Nagai
    • Journal Title

      Phys. Rev. C 56

      Pages: 3173-3179

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Measurement of the 13C(n, γ)14C cross secton at stellar energies1997

    • Author(s)
      T. Shima
    • Journal Title

      Nucl. Phys. A621

      Pages: 231c-234c

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] 127I(n, γ)128I reaction in NaI(Tl)due to cosmic-ray muon capture by Pb1996

    • Author(s)
      Y. Nagai
    • Journal Title

      Nucl. Instr. Meth. 103

      Pages: 498-502

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Fast neutron capture reactions in nuclear astrophysics1996

    • Author(s)
      Y. Nagai
    • Journal Title

      Hyp Int. 103

      Pages: 43-48

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] 127I(n, γ)128I reaction in NaI(Tl) due to cosmic-ray muon capture by Pb1996

    • Author(s)
      Y. Nagai
    • Journal Title

      Nucl. Instr. Meth. 103

      Pages: 498-502

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Fast neutron capture reactions in nuclear astrophysics1996

    • Author(s)
      Y. Nagai
    • Journal Title

      Hyp. Int. 103

      Pages: 43-48

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] A gas scntillation drift chamber for the 14N(n, p)14C measurement1995

    • Author(s)
      T. Shina
    • Journal Title

      Nucl. Instr. Meth. A356

      Pages: 34-335

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Measurement of the 16O(n, γ), 17O reaction cross section at stellar energy and the critical role of non-resonant p-wave neutron capture1995

    • Author(s)
      M. Igashira
    • Journal Title

      The Astrophys. J. Letter 441

      Pages: L89-L92

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] First measurement of a p(n, γ)d reaction cross section between 10 and 80 keV1995

    • Author(s)
      T. S. Suzuki
    • Journal Title

      The Astrophys. J. Letter 439

      Pages: L59-L62

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] A gas scntillation drift chamber for the 14N.(n, p)14C measurement1995

    • Author(s)
      T. Shima
    • Journal Title

      Nucl. Instr. Meth. A356

      Pages: 347-355

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Measurement of the 16O(n, γ)17O reaction cross section at stellar energy and the critical role of nonresonant p-wave neutron capture1995

    • Author(s)
      M. Igashira
    • Journal Title

      The Astrophys. J. Letter 441

      Pages: L89-L92

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Neutron Capture Reactions of^<84>Kr, ^<20>Ne, and^<22>Ne and Steller Nucleosynthesis

    • Author(s)
      東名敦志
    • Journal Title

      原子核研究 47巻3号

      Pages: 17-24

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Neutron Capture Reactions of ^<84>Kr, ^<20>Ne, and ^<22>Ne and Steller Nucleosynthesis

    • Author(s)
      A. Tomyo
    • Journal Title

      Genshikakukenkyu Vol. 47 No. 3

      Pages: 17-24

    • Description
      「研究成果報告書概要(欧文)」より
  • [Patent(Industrial Property Rights)] 放射線検出器の非一様性の検査方法1995

    • Inventor(s)
      永井泰樹
    • Industrial Property Rights Holder
      東京工業大学長
    • Industrial Property Number
      特許第2671952号
    • Filing Date
      1995-09-25
    • Acquisition Date
      1997-07-11
    • Description
      「研究成果報告書概要(和文)」より

URL: 

Published: 2010-06-09  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi