U, Np, Pu & Am Prompt Fission Neutron Spectra

Prompt fission neutron spectra (PFNS) components due to soft and hard pre‐fission neutrons are revealed in PFNS data of 232Th(n,F), 238U(n,F), 235U(n,F) and 239Pu(n,F) reactions for En⩽20 MeV. Average energies 〈E〉 of these PFNS are systematically shifted to higher values, so that Th fission fragments look least heated, while those of Pu—most heated. The average energy 〈E〉 is correlated with the emissive fission chances contributions to the observed fission cross sections. The predicted contribution of (n,xnf) neutrons is most pronounced in case of 232Th(n,F) reaction. The approach, based on the consistent description of 237Np(n,F), 237Np(n,2n)236sNp and 241Am(n,F), 241Am(n,2n) is used to predict the PFNS of the 237Np(n,F) and 241Am(n,F) reactions.