1994 Fiscal Year Final Research Report Summary
Study of Pre-equilibrium Process by Sudden Approximation
| Project/Area Number |
04640309
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | Ishinomaki Senshuu University |
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Principal Investigator |
YOSHIDA Shiro Ishinomaki Senshuu University, Faculty of Science and Thechnology, Professor, 理工学部, 教授 (60091766)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Yoshio Yamagata University, Faculty of General Education, Professor, 教養部, 教授 (10113961)
ABE Masanori Ishinomaki Senshuu University, Faculty of Science and Thechnology, Lecturer, 理工学部, 講師 (50221049)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Pre-equllibrium process / Absorptive Potential / Statistical Theory of Nuclear Reaction / Dynamical Shell Model / Semiclassical Approximation |
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| Research Abstract |
Preequilibrium multistep compound process is described by the master equation, which is derived under the statistical assumption. Parameters appeared there are obtained from an absorptive potential with fixed exction number. The potential is calculated by using the delta-interaction and furthermore the transmission coefficients are obtained. From which stage of the multistep direct process the multistep compound process starts had been a question. We calculated contributions from the first stage and the second stage and both are found to be equally important. This agrees with conclusions from phenomenological analyzes. However the Pauli blocking effect are not taken into account in the absorptive potentials.
As a temperature fixed state is a mixture of various exciton states, the absorptive potential with fixed temperature is decomposed into ones for various exciton states, and absorptive potential for preequilibrium processes are obtained Under the Fermi liquid approximation the calculation is analytically performed. On the other hand the numerical calculations with delta interaction is also performed, and both results are compared. When intermediates states are limited to bound configurations like in the case of pre-equilibrium process, agreements become worse as the incident energy increases, while if the intermediate states are not restricted agreements are pretty good. In this calculation the effect of Pauli blocking is taken into account.
Transition probabilities between exciton states are obtained by the second moment of the interaction if the matrix elements are random. The second moments are obtained from the spreading width, which is calculated from the absorptive potential. If the semiclassical approximation is adopted then the spreading widths are obtained as a function of energy for a fixed spin-parity state. These results are useful for studies of preequilibrium as well as the dynamical shell model.
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