Analysis of dynamical process with mass distribution of fission fragmentin heavy ion reactions

Abstract

We analyzed experimental data obtained for the mass distribution of fission fragments in the reac- tions 36 S+ 238 U and 30 Si+ 238 U at several incident energies, which were performed by the JAEA group. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. We also consider the fine structure s in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has di fferent features in the two reactions. The fusion cross sections are also e stimated. the reactions 36 S+ 238 U and 30 Si+ 238 U at several incident energies, which were measured by the JAEA group (3, 4). The analysis of the mass distribution of fission fragments is a powerful tool for investigating the mechanism of the reaction in the heavy- and superheavy-mass regions. Us- ing the dynamical model, we precisely investigate the in- cident energy dependence of mass distribution of fission fragments. This study is the first attempt to treat such ex- perimental data systematically. We also consider the fine structures in the mass distribution of fission fragments cau sed by the shell structure at a low incident energy. In the reac- tion 30 Si+ 238 U, there are two peaks at approximately A = 90 and 178 at a low incident energy, which do not corre- spond to nuclei with a closed shell. Using our model, we analyze the data obtained from this reaction in an attempt to understand the origin of these peaks. We also calculate the capture cross sectionσcap and the fusion cross section σ f us, and compare them with the experimental data.