Dynamical study of fission process at low excitation energies in the framework of the four-dimensional Langevin equations

A stochastic approach based on four-dimensional Langevin equations has been used to estimate the fission probability, the mean kinetic energy of fission fragments, the mean prompt neutron multiplicity, the average pre-scission neutron multiplicity and the mass distribution of fission fragments for the compound nucleus 238Np produced in neutron induced reaction at low excitation energy. 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, dissipation was generated through the chaos weighted wall and window friction formula and dissipation coefficient of K, γK, considered as a non-constant parameter. Comparison of the theoretical results with the above mentioned experimental data showed that different features of fission of the excited compound uncles 238Np at low excitation energy can be satisfactorily reproduced by the four dimensional Langevin equations.