هادی اسلامی زاده

The fission process of the excited compound nucleus 240Pu produced in neutron-induced reaction at incident energies from thermal to 14 MeV has been simulated by using a stochastic approach based on four-dimensional Langevin equations. The fission cross section, the total kinetic energy of fission fragments, the mass distribution of fission fragments, the average prompt neutron multiplicity, the average spin of fission fragments and the mean fission time have been calculated for the excited compound nucleus 240Pu. Three collective shape coordinates plus the projection of total spin of the compound nucleus to the symmetry axis, k , were considered in the four-dimensional dynamical model. In the dynamical calculations was examined the effect of the neck radius in the scission configuration on the total kinetic energy of fission fragments of 240Pu nucleus. In the dynamical calculations, nuclear dissipation was generated through the chaos weighted wall and window friction formula with a chaoticity coefficient. In the calculations, the chaoticity coefficient was considered as a free parameter and its magnitude inferred for 240Pu by fitting measured data on the fission cross section. It was shown that the results of calculations for the fission cross section are in good agreement with the experimental data by using the magnitude of the chaoticity coefficient equal to 0.4. Furthermore, by reproducing experimental data on the total kinetic energy of fission fragments for the excited compound nucleus 240Pu has been inferred the magnitude of the neck radius at which rupture occurs. It was shown that the results of the total kinetic energy of fission fragments are very sensitive to the value of the neck radius at which rupture occurs. It was also shown that the results of calculations for the total kinetic energy of fission fragments for 240Pu are in good agreement with the experimental data by using the magnitude of the radius in the scission configuration equal to 2.2 fm. Fur