| Project/Area Number |
15340085
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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 | High energy Accelerator Research Organization (2004)
The High Energy Accelerator Research Organization (2003) |
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Principal Investigator |
MIYATAKE Hiroari IPNS, ASSOCIATE PROFESSOR, 素粒子原子核研究所, 助教授 (50190799)
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| Co-Investigator(Kenkyū-buntansha) |
JEONG Sunchan IPNS, ASSOCIATE PROFESSOR, 素粒子原子核研究所, 助教授 (00262105)
ISHIYAMA Hironobu IPNS, RESEARCH ASSOCIATE, 素粒子原子核研究所, 助手 (50321534)
WATANABE Yutaka IPNS, RESEARCH ASSOCIATE, 素粒子原子核研究所, 助手 (50353363)
SHIMODA Tadashi OSAKA UNIV., FACULTY OF SCIENCE, PROFESSOR, 大学院・理学研究科, 教授 (70135656)
MITSUOKA Shinichi JAERI, DEPT. OF MATERIAL SCIENCE, RESEARCHER, 物質科学部, 研究員 (40354881)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥16,700,000 (Direct Cost: ¥16,700,000)
Fiscal Year 2004: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 2003: ¥12,200,000 (Direct Cost: ¥12,200,000)
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| Keywords | nuclear astrophysics / radioactive nuclear beams / nuclear physics / rapid neutron capture process / neutron-rich nuclei / laser ion-source / nuclear spin-polarizatinn / スピン偏極 / г-過程 |
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| Research Abstract |
In this project, we studied seed-nuclei creation process prior to the possible rapid neutron capture at the moment of the type II supernova explosion his process has been believed to occur from proton and neutron, which create heavy elements in the seed region consisting of iron and nickel isotopes thorough nuclear reactions like (alpha, n) and (n, gamma). So far, time dependence of relevant element abundance in this process has been estimated by a large nuclear reaction network code based on the predicted reaction rates of the statistical model. However, the statistical prediction in dais light nuclear region keeps little confidence for its predictability due to the small level densities. Therefore a direct measurement of astrophysical reaction rate becomes issue to further quantitative investigation of the above synthesis senarios.
We have measured systematically the (alpha, n) reaction cross sections by using light neutron rich radioactive nuclear beams and efficient detector system, which makes it possible to measure excitation functions exclusively in fine broad energy region. In this project, we observed 8^Li,^<12>B, and ^<16>N (alpha, n) reaction cross sections. The obtained excitation function of the ^8Li experiment has 10 times higher statistics and deduced reaction rates are about a half values compared to the previous ones. This indicates that the ^8Li(alpha, n) reaction rate as well as resultant neutron number density should be suppressed in the element synthesis senarios so that mass abundance pattern of the r-process will be changed.
As a part of this project, we have also proceeded to study technical aspects of a laser ion-source and a new nuclear-spectroscopy with spun-polarized radioactive nuclei, which are important developments for further astrophysical studies at a new radioactive nuclear beam facility constructing at JAERI.
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