Dependence of the average total kinetic energy of fission fragments on incident neutron energy studied by a 4D Langevin model

Shimada, Kazuya ; Ishizuka, Chikako*; Chiba, Satoshi*

TKE (total kinetic energy), one of the nuclear data, is the kinetic energy of fission fragments, and influences not only the energy obtained in nuclear fission, but also the criticality safety assessment. Exploring the underlying factors influencing TKE is vital for fundamental research and utilization of nuclear energy. Instinctively, it is expected that as the energy of incident neutrons on the target nucleus increases, thus leading to a corresponding increase in TKE. However, experimental evidence suggests that TKE decreases as the excitation energy increases. In this study, we investigate this phenomenon. The four-dimensional Langevin model captures the overall shape of the nuclear fission fragment as Brownian motion until the nuclear fission. Using this model, we calculated the excitation energy dependence of TKE. Our investigation reveals that the decreasing trend in TKE can be attributed to the deformation of the heavy fission fragments.