هادی اسلامی زاده

The fission probability, pre-scission neutron, proton and alpha multiplicities, anisotropy of fission fragment angular distribution and the fission time have been calculated for the compound nuclei 200Pb and 197Tl based on the modified statistical model and four-dimensional dynamical model. In dynamical calculations, dissipation was generated through the chaos weighted wall and window friction formula. The projection of the total spin of the compound nucleus to the symmetry axis, K, was considered as the fourth-dimension in Langevin dynamical calculations. In our dynamical calculations, we have used a constant dissipation coefficient of K, K 0.077(MeV zs) , ? = ?1/2 and a nonconstant dissipation coefficient to reproduce the above-mentioned experimental data. Comparison of the theoretical results of the fission probability and pre-scission particle multiplicities with the experimental data showed that the difference between the results of both dynamical models is small whereas, for the anisotropy of fission fragment angular istribution, it is slightly large. Furthermore, comparison of the results of the modified statistical model with the above-mentioned experimental data showed that with choosing appropriate values of the temperature coefficient of the effective potential, ?, and the scaling factor of the fission-barrier height, rs, the experimental data were satisfactorily reproduced