^(40)Ca和^(208)Pb快中子辐射俘获过程研究  

Stuty on the Process of the Fast Neutron Radiative Capture for ^(40)Ca and^(208) Pb

作　　者：刘建峰[1] 赵维娟[1] 

机构地区：[1]郑州大学物理系,郑州450052

出　　处：《高能物理与核物理》2002年第11期1158-1165,共8页High Energy Physics and Nuclear Physics

基　　金：中国核工业集团总公司核数据经费;河南省科委基金(0 0 40 5 1 5 0 0 )资助~~

摘　　要：对快中子引起的核反应作预平衡修正 ,即考虑直接 -半直接俘获作为统计平衡前 1激子态和 3激子态的γ发射过程 ,5个及 5个以上激子态的粒子 (中子、质子及α粒子等 )及γ发射过程用达到统计平衡的复合核过程描述 ,在中子入射能量 3MeV至 2 0MeV能区对 4 0 Ca和 2 0 8Pb的辐射俘获截面进行了理论计算并与实验结果作了比较 ,得到了较好符合的结果 .同时 ,对统计平衡前后γ发射对 (n ,γ)截面的贡献及直接俘获。The pre equilibrium correction for the nuclear reactions induced by fast neutron is considered as follows: the nuclear reaction processes with the exciton number equal to or larger than five can still be described by the statistical theory of the nuclear reaction. The particle emission processes, in which less than five excitons are involved, are calculated by means of the exciton model and the γ emission of one exciton state is calculated by the direct capture mechanism. For the three exciton state, only the semidirect capture mechanism, which plays the main role in the researched energy region, is taken into account. The interference effect between the direct and semidirect capture is also considered. The radiative capture cross sections for 40 Ca and 208 Pb in the neutron incident energy region from 3 MeV to 20 MeV are calculated and a better coincidence with the experimental values is obtained. At the same time, the contribution to the (n, γ) reaction cross sections of the γ emissions before and after statistical equilibriums as well as the characteristics of the direct capture, semidirect capture and their interferece terms are discussed.

关 键 词：^40Ca ^208PB 快中子辐射俘获 直接-半直接俘获 复合核统计过程 预平衡γ发射 钙40 铅208 核反应 

分 类 号：O571.5[理学—粒子物理与原子核物理]