Monte Carlo approach to sequential neutron emission from fission fragments

We have implemented a Monte Carlo simulation of fission fragment statistical decay by sequential neutron emission. Within this approach, we calculate the center-of-mass and laboratory prompt neutron energy spectra as a function of the mass of fission fragments and integrated over the whole mass distribution. We also assess the prompt neutron multiplicity distribution P(ν), both the average number of emitted neutrons and the average neutron energy as a function of the mass of the fission fragments [respectively ν(A) and ε(A)]. We investigate the average total energy available for prompt {γ}-ray emission as a function of the mass of the fission fragments Ē_γ(A). We also calculate neutron-neutron correlations such as the full matrix ν(A,TKE) as well as correlations between neutron energies. Two assumptions for partitioning the total available excitation energy among the light and heavy fragments are considered. Results are reported for the neutron-induced fission of ²³⁵U (at neutron energy of 0.53 MeV) and for the spontaneous fission of ²⁵²Cf.