Theoretical Studies Of Isospin Effect For The De-excitation Process Of Hot Nuclei Based With Pathwise Analysis Method

The isospin effect of heavy-ion nuclear reaction is one of frontier subjects in heavy-ion physics. It is interesting that there distinctly appears isospin effect in the deexcitation process of heavy isotopic nuclei which produced in fusion reaction. With current research progress, in this thesis we select two isotopic chains where213Fr contains neutron shell closure (N=126), and study the influence of deformation dependence of two key-physics quantum (nuclear dissipation and level density parameter) on the isospin effect of deexcitation process of hot nuclei.For that, we firstly make a brief introduce about nuclear dissipation in chapter1, and a detailed description for statistical models, the combined dynamical and statistical model (CDSM), and the pathwise analysis method.Next, we carry out numerical simulations for the deexcitation process of nine nuclei which from two isotopic chains209,211,213,215,217Fr and210,212,214,216Rn based on CDSM model. For deeply study, in calculations we take two different nuclear frictions (SPS and OBD) as well as two kinds of deformation dependences of level density parameter. The results show:(1)The difference about saddle point and thermodynamics driving force for isotopic nuclei results in that the more isospin factor is larger, the more the emission of prescission neutron becomes stronger. The emission of prescission charged particles is quite contrary.(2) The different deformation dependences of nuclear dissipation and level density parameter place no influence on the isospin effect of prescission particle emission.(3) Due to the dynamical effect of shell correction is not taken into account in present work, the isospin effect of deexcitation process of hot nuclei do not appear abnormal phenomena.The present work suggests that the dynamical effect of shell correction must be included into next research work to obtain more credible information in view that the deexcitation process of hot nuclei in nature is a acutely deformation evolvement process of quantum many body-system.