Multimodal analysis of prompt neutron spectra for 238Pu(sf), 240Pu(sf), 242Pu(sf) and 239Pu(nth,f) Original Research Article

The prompt neutron spectra for View the MathML source(sf), View the MathML source(sf), View the MathML source(sf) and View the MathML source(nView the MathML source,f) were calculated with the modified Madland–Nix model with consideration to the multimodal nature of the fission process. The spectra of neutrons for each mode (Standard-I, -II, -III) were calculated independently and the total spectra were synthesized. The partial spectra for the three modes were found to be considerably different from each other. Different mode branching ratios resulted in different total spectra for the three even-mass spontaneously fissioning isotopes. Comparison of spectra for View the MathML source(sf) and View the MathML source(nView the MathML source,f), for which the fissioning nucleus is the same, revealed that the total spectra were harder for View the MathML source(nView the MathML source,f) due to the higher excitation energy of the fissioning nucleus. The calculated total spectra well represented the experimental data.