Post-fission properties of uranium isotopes: a hybrid method with Langevin dynamics and the Hauser-Feshbach statistical model

In this study, we present a new method to describe the dynamical fission process and following prompt-neutron emission, where the fission calculation based on the Langevin method and the Hauser-Feshbach statistical model are combined. Two methods are connected smoothly within the universal charge distribution and the energy conservation, allowing us to calculate a sequence of fission dynamics and post-fission phase including prompt neutron emission. Using a certain set of model parameters, we successfully reproduce experimental fission-fragment distributions, total kinetic energy, and prompt neutron emissions for the neutron induced fission of ²³⁵U. Additionally, we apply our calculation to two very neutron-rich uranium isotopes, i.e., ²⁵⁰U and ²⁵⁵U, which are not experimentally confirmed, but are relevant to r-process nucleosynthesis. Our method successfully predicts post-neutron emission fragment distributions, where ²⁵⁰U shows a stronger neutron emissivity than ²⁵⁵U. The predictions of the calculations, which are highly reproducible in the experiments, show that not only the distribution of fission variables but also the number of neutron emissions differ significantly in neutron-rich uranium fission.