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Study of Pre-equilibrium Process by Sudden Approximation

突变逼近研究预平衡过程

基本信息

批准号：
04640309
负责人：
YOSHIDA Shiro
金额：
$ 1.34万
依托单位：
Ishinomaki Senshuu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

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.

在统计假设下，用主方程描述预平衡多步复合过程。出现的参数是从固定激发点数的吸收势中得到的。利用增量相互作用计算了势能，进而得到了传输系数。从多步直接工艺的哪个阶段开始，多步复合工艺一直是个问题。我们计算了第一阶段和第二阶段的贡献，发现两者同样重要。这与现象学分析得出的结论一致。由于定温态是各种激子态的混合态，将定温的吸收势分解为各种激子态的定温吸收势，在费米液体近似下得到了预平衡过程的吸收势，并进行了解析计算。另一方面，还进行了考虑Delta相互作用的数值计算，并对两种计算结果进行了比较。当中间态被限制为束缚组态时，如在预平衡过程中，协议随着入射能量的增加而变差，而如果中间态不受限制，协议是相当好的。在计算中考虑了泡利阻塞的影响，如果矩阵元素是随机的，则通过相互作用的二阶矩得到激子态之间的跃迁几率。二阶矩由展宽获得，展宽是根据吸收势计算的。如果采用半经典近似，则对于固定的自旋-宇称态，扩展宽度是能量的函数。这些结果对研究准平衡和动态壳模型有一定的参考价值。