| Project/Area Number |
07640401
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Osaka University |
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Principal Investigator |
NORO Tetsuo Research Center for Nuclear Physics, Osaka University, associate proffesor, 核物理研究センター, 助教授 (30164750)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAGUCHI Harutaka Department of Physics, Kyoto University, associate proffesor, 理学部, 助教授 (30025465)
HATANAKA Kichiji Research Center for Nuclear Physics, Osaka University, associate proffesor, 核物理研究センター, 助教授 (50144530)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1996: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1995: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | quasifree scattering / medium effect / nucleon-nucleon scattering amplitude / Dirac approach / effective mass / analyzing power / 偏極移行 |
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| Research Abstract |
Nuclear medium effect has been investigated experimentally through nucleon quasifree scattering. Exclusive measurements of the quasifree scattering give a direct way to study the nucleon-nucleon interaction in nuclear medium and is is expected to extract information on the properties of nucleons and mesons in nuclear field. For this puroose, defferential cross sections and analyzing powers (Ay) have been measured for the proton knockout reaction from s_<1/2> orbits of several target nuclei by using the ring cyclotron at Research Center for Nuclear Physics, Osaka University. The Ay values are reduce from those of free proton-proton scattering and the reduction rate is found to depend on target. We found that an averaged density seen through this reaction can be estimated in a special case where the recoil momentum, which corresponds to the experimental setting employed in this study, is zero and it reaches almost half of the nuclear saturation density in some cases. The reduction of Ay shows a monotomically decreasing function of the averaged density, which strongly suggests the existence of a nuclear medium effect on the nucleon-nucleon interaction. This result has been compared with the prediction by the Dirac approach. In this approach, , modification of the nucleon spinor in nuclear field is described as a reduction of the effective nucleon mass. We estimate the effective nucleon mass by using the averaged density defined above and calculate the modefication of the nucleon-nucleon observables by following the procedure proposed by a theoretical group in Indiana university. The calculation gives a qualitatively consistent result with our experimental result.
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