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STUDAY OF NUCLEOSYNTHESIS USING keV NEUTRONS

Research Project

Project/Area Number 04452024
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 核・宇宙線・素粒子
Research InstitutionTOKYO INSTITUTE OF TECHNOLOGY

Principal Investigator

NAGAI Yasuki  TOKYO INSTITUTE OF TECHNOLOGY, DEPARTMENT OF APPLIED PHYSICS, PROFESSOR, 理学部, 教授 (80028240)

Co-Investigator(Kenkyū-buntansha) KAJINO Tositaka  NATIONAL ASTRONOMICAL OBSERVATORY, ASSOCIATE PROFESSOR, 助教授 (20169444)
OGURI Takayuki  TOKYO INSTITUTE OF TECHNOLOFY, RESEARCH LABORATORY FOR NUCLEAR REACTOR, RESEARCH, 原子炉工学研究所, 助手 (90160829)
IGASHIRA Masayuki  TOKYO INSTITUTE OF TECHNOLOGY, RESEARCH LABORATORY FOR NUCLEAR REACTOR, ASSOCIAT, 原子炉工学研究所, 助教授 (10114852)
SHIMA Tatusi  TOKYO INSTITUTE OF TECHNOLOGY, DEPARTMENT OF APPLIED PHYSICS, RESEARCH ASSOCIATE, 理学部, 助手 (10222035)
ASAHI Kouichirou  TOKYO INSTITUTE OF TECHNOLOGY, DEPARTMENT OF APPLIED PHYSICS, ASSOLATE PROFESSOR, 理学部, 助教授 (80114354)
Project Period (FY) 1992 – 1993
Project Status Completed (Fiscal Year 1993)
Budget Amount *help
¥8,400,000 (Direct Cost: ¥8,400,000)
Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1992: ¥7,600,000 (Direct Cost: ¥7,600,000)
Keywordsstar / nucleosynthesis / neutron / reaction cross section / gas scintillation / drift chamber / p-wave neutron capture / simulation / P波中性子捕獲 / S過程元素合成 / 中性子捕獲 / データ収集計算機 / 中性子散乱 / モンテカルロコード
Research Abstract

It is quite important to measure the cross section of the ^<14>N(n, p) ^<14>C reaction at the stellar neutron energy, 10 - 250 keV, to investigate the nucleosynthesis in stara. In order to measure the cross section we have developed the new type of a gas scintillation drift chamber, operating in the N_2 gas. After constructing the chamber we did the off-line test using the alpha source. Good resolutions of energy and time were obtained as expected. In the on-line test, the average cross section of 1.3 mbarn was obtained at the average of 40 keV.Although another ezperiment to get higher statistics is certainly important, the above preliminary result indicates that the N is likely to absord neutrons for the s-process especially in metal deficient stars.
The experimental data of the ^<12>C(n, gamma) ^<13>C reaction have been analyzed and for the first time we obtained the accurate cross section in the neutron energies between 10 - 250 keV.From the present resunt it turned out that the carbon acts as a neutron poison in massive metal-deficient stars. The result may affect strongly the scinario of the nucleosynthesis in stars. Furthermore, it was shown for the first time that the cross section increases as the neutron energy increases. This is due to the contribution of the non-direct p-wave capture, which was deduced from the energy dependence of the cross section and the gamma -ray branching ratio from a capturing state.
In the neutron capture reaction large amounts of samples are used, as the cross section is usually very small. Therefore it is important to correct properly the multiple scattering events in the thick sample. For the correction wedeveloped a Monte Garlo code and the validity of the code was tested by using paraffine samples with various thickness.

Report

(3 results)
  • 1993 Annual Research Report   Final Research Report Summary
  • 1992 Annual Research Report
  • Research Products

    (22 results)

All Other

All Publications (22 results)

  • [Publications] Y.Nagai: ""(n,γ) reaction of light nuclei in nuclear astrophysics"" Proceeding of the 8th Int.Symp.on Capture Gamma-Ray Spectroscopy and Related Topics. 734-741 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Senoo,Y.Nagai: "Simulation of multiple neutron scattering events in the thick sample for (n,) experiments" Proceeding of the 8th Int.Symp.on Capture Gamma-Ray Spectroscopy and Related Topics. 1007-1009 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] T.Ohsaki,Y.Nagai: "New measurement of the ^<12>C(n,γ) ^<13>c reaction cross section" Astrophys,J.422. 912-916 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Senoo,Y.Nagai: "A Monte-Carlo code for multiple neutron scattering events in a thick sample for (n,γ) experiments" Nucl.Instr.Meth.A339. 556-563 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] H.Sakai,Y.Nagai: "Spectroscopy of neutron halo nucleus ^<11>Be via the ^<11>Be(d,^2He) reaction at 70 MeV" Phys.Lett.7. 7-12 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] Y.Nagai: "Nuclear astrophysics and critical roles of nuclear data" JAERI-M. (印刷中). (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] Y.Nagai: "(n, gamma) reaction of light nuclei in nuclear astrophysics" Proc. of the 8th Int. Symp. on Capture Gamma-Ray Spectroscopy and Related Topics. 734-741 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Senoo Y.Nagai: "Simulation of Multiple Neutron Scatterring Events in the Thick Sample" Proc. of the 8th Int. Symp. on Capture Gamma-Ray Spectroscopy and Related Topics. 1007-1009 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] T.Ohsaki Y.Nagai: "New Measurement of the ^<12>C(n, gamma) ^<13>C Reaction Cross Section" The Astrophysical Journal. 422. 912-916 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Senoo Y.Nagai: "A Monte Carlo Code for Multiple Neutron Scattering Events in a Thick Sample for (n, gamma) Experiments" Nuclear Instruments and Method. A339. 556-563 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] H.Sakai Y.Nagai: "Spectroscopy of Neutron Halo Nucleus ^<11>Be via ^<11>Be (d, ^2He) reaction at 70 MeV" Physics Letter. 7. 7-12 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] Y.Nagai: "Nucleae astrophysics and Critical aroles of Nuclear Data" JAERI. (in press). (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] Y.Nagai: "“(n,γ)reaotion of light nuclei in nuclear astrophysics"" Proceeding of the 8th Int.Symp.on Capture Gamma-Ray Spectroscopy and Related Topics. (印刷中). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] K.Senoo,Y.Nagai: "Simulation of multiple neutron scattering events in the thick sample for(n,)experiments" Proceeding of the 8th Int.Symp.on Capture Gamma-Ray Spectroscopy and Related Topics. (印刷中). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] T.Ohsaki,Y.Nagai: "New measurement of the ^<12>C(n,γ) ^<13>c reaction cross section'" Astrophys.J.(印刷中). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] K.Senoo,Y.Nagai: "A Monte-Carlo code for multiple neutron scattering events in a thick sample for(n,γ)experiments" Nucl.Instr.Meth.(印刷中). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] H.Sakai,Y.Nagai: "Spectroscopy of neutron halo nucleus ^<11>Be via the ^<11>Be(d,^2He) reaction at 70 MeV" Phys.Lett.7. 7-12 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] Y.Nagai: "Nuclear astrophysics and critical roles of nuclear data" JAERI-M. (印刷中). (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] Y,Nagai: "Neutron capture rates of light nuclei and stellar evolution" proceeding 2nd Int.Symp.on Nuclear Astrophysics. Nuclei in the COSMOS. (1993)

    • Related Report
      1992 Annual Research Report
  • [Publications] Y.Nagai: "stellar neutron capture cross sections of light nuclei" proceeding Mini Int.Symp.on origin and Evolution of the Elements. (1993)

    • Related Report
      1992 Annual Research Report
  • [Publications] Y.Nagai: "(n,γ)reaction related to nuclear astrophysics" proceeding Japan-China Joint Nuclear Physics Symp.(1993)

    • Related Report
      1992 Annual Research Report
  • [Publications] 嶋 達志: "中性子ビームによる実験の展望" 研究会「短寿命核ビームの科学'92」報告書. (1993)

    • Related Report
      1992 Annual Research Report

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Published: 1992-04-01   Modified: 2016-04-21  

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