权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Statistical Theory of Nuclear Reaction

核反应统计理论

基本信息

批准号：
63540204
负责人：
YOSHIDA Shiro
金额：
$ 1.22万
依托单位：
Ishinomaki Senshu University (1989-1990)Yamagata University (1988)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63540204/
关键词：
Nuclear reaction Statistical theory of nuclear reaction Multistep compound process Partial level density Level density Decay of giant resonance 複合核反応前平衡過程直接相互作用 2次モ-メント統計理論ゆらぎの断面積巨大共鳴の幅

项目摘要

Using novel method of generating function Grassmann integral developed by Weidenmiiller's group we studied the statistical theory of nuclear reactions and related problems to obtain results to be compared with experimental data. For equilibrium compound process, effects of direct interaction are included by the inverse of NishiokaーWeidenmuller transformation. The effects are mainly contained in the transmission matrix. Is studying decay of giant resonances the transmission matrix is calculated, which is used to evaluate the direct interaction effects on multistep compound process. In this case the imaginary part of optical potential whose absorption is limited to bound configuration must be used.In studying nuclear reactions partial level densities (PLD) are necessary. Including independent particle model spectra and random residual in reaction we have been continuing work on PLD. To be realistic spin parity assignment is now included. By neglecting Pauliーprinciple consistently we were ableto calculate PLD with reasonable computing time without spoiling the accuracy. Experimental data high spin states of ^<208>Pb by inelastic scattering of proton was explained fairly well by our PLD.By using simple model the multistep compound reaction cross sections are evaluated neglecting direct reaction effects for ^<40>Ca and ^<280>Pb. Both strong and weak couplings are assumed. In strong coupling case the reaction proceeds to high excitation states with less neutron emission compared with the weak coupling case. For ^<280>Pb fluctuation cross section is found to vanish in the weak coupling limit because of lack of levels in these energy regions. So far out study is limited to closed shell nuclei, but we hope to extend to open shell spherical nuclei by introducing pairing correlation.

利用Weidenmiiller小组提出的生成函数Grassmann积分的新方法，对核反应的统计理论及相关问题进行了研究，得到了与实验数据相比较的结果。对于平衡复合过程，直接相互作用的影响包括在Nishioka - Weidenmuller变换的逆中。这些影响主要包含在传输矩阵中。在研究巨共振衰减时，计算了传输矩阵，用于评价多步复合过程的直接相互作用效应。在这种情况下，必须使用吸收仅限于束缚位的光势的虚部。在研究核反应时，部分能级密度（PLD）是必要的。包括独立的粒子模型谱和反应中的随机残差，我们一直在继续PLD的研究。为了现实，现在包括了自旋宇称赋值。通过始终忽略泡利原理，我们可以在不影响精度的情况下，在合理的计算时间内计算出PLD。我们的PLD很好地解释了质子非弹性散射导致的^<208>Pb的高自旋态。采用简单模型，忽略了^<40>Ca和^<280>Pb的直接反应效应，计算了多步复合反应截面。强耦合和弱耦合都是假定的。与弱耦合情况相比，在强耦合情况下，反应进入高激发态，中子发射较少。对于^<280>，由于在这些能量区域缺乏能级，Pb的波动截面在弱耦合极限中消失。目前我们的研究仅限于闭壳核，但我们希望通过引入配对相关将其扩展到开壳球核。