| Project/Area Number |
17340078
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Osaka University |
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Principal Investigator |
NAGAI Yasuki Research Center for Nuclear Physics, Professor, 核物理研究センター, 教授 (80028240)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMA Tatsushi Research Center for Nuclear Physics, Research Associate, 核物理研究センター, 助手 (10222035)
TAKAHISA Keiji Research Center for Nuclear Physics, Research Associate, 核物理研究センター, 助手 (30263338)
IGASHIRA Masayuki Tokyo Inst. Tech., Res. Lab. Nucl. Reactors, Associate Professor, 原子炉工学研究所, 助教授 (10114852)
KAJINO Toshitaka National Astronomical Observatory of Japan, Associate Professor, 理論部, 助教授 (20169444)
大崎 敏郎 東京工業大学, 原子炉研, 助手 (80262327)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥15,300,000 (Direct Cost: ¥15,300,000)
Fiscal Year 2006: ¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2005: ¥11,400,000 (Direct Cost: ¥11,400,000)
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| Keywords | stellar nucleosynthesis / neutron capture reaction / s-process / thermal energy / doorway state / metal-deficient star / 超金属欠乏星 / s過程元素 / keV中性子 / NaI検出器 / 即発ガンマ線 / マックスウエル断面積 |
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| Research Abstract |
Recently, the nucleosynthetic yields of massive stars of solar metallicity have been calculated from the onset of central hydrogen burning through explosions as Type II supernovae by Rauscher et al.. According to the calculation, the yields from Ni isotopes and Sr isotopes are overproduced by about 30. This overproduction factor is compared to the general overproduction of 10. Hence, the yields of former isotopes are overproduced by a factor three. This problem of overproduction has been one of the problems remaining in such calculations of the slow process nucleosynthetic yields. The origin of the overproduction is considered to be due to the uncertainty of the neutron capture cross section of nuclei relevant to the nucleosynthesis. In the present study we aimed at measuring the neutron capture cross section of ^<62>Ni in the resonance energy region of 4.5 keV by developing an experimental method. We succeeded to accurately determine the cross section, and thus the overproduction mentioned above turned out to be the uncertainty of the cross section used in the nucleosynthetic calculations.
The neutron capture cross section of ^<18>O has been also measured at thermal and keV energies to study a possible influence of ^<18>O as a neutron poison. In this study, we found for the first time that the thermal capture reaction proceeded via a neutron capture by the two-hole four-particle configuration of ^<18>O. This finding would affect considerably in the neutron capture process both at thermal and keV energies.
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