ILL, Grenoble

Fragment excitation, moments of the kinetic energy distributions and neutron evaporation in nuclear fission calculated from a random excitation model

We present a model which allows the calculation of fragment excitation energy, kinetic energies and neutron evaporation in nuclear fission. The model is based on the assumption that, at the end of the fission process, fragments are excited to a temperature which is proportional to the reaction Q-value. Starting from this assumption we give expressions for the distributions of fragment excitation and the kinetic energy. From the distributions of the excitation energy neutron evaporation characteristics are calculated. The results of the model are compared to experimental data from various compound systems ranging from Radium- to Fermium-isotopes. It will be shown that the constant which determines how much of the Q-value is taken to bring the fragments to a final temperature T is independent of the compound nucleus, independent of the reaction which leads to fission, and independent of the fragment masses.