Spin-Dependent Calculation of Fission Neutron Spectra and Fission Spectrum Integrals for Six Fissioning Systems

Calculations of fission neutron spectra and fission spectrum integrals for six fissioning systems are reported. The systems studied are thermal-neutron-induced fission of ²³³U, ²³⁵U, and ²³⁹Pu; 2-MeV neutron fission of ²³²Th and ²³⁸U; and spontaneous fission of ²⁵²Cf The Madland-Nix formalism is used, but is extended to take account of the spin of the fission fragment. Also, more recent values for the average energy release in fission are used. The results of the fission neutron spectrum calculations are given in tabular and graphical form for applied purposes and are compared with experimental data. Similar deviations from a Maxwellian spectrum are seen for each system. The effect on the fission neutron spectra of ²³³U, ²³⁵U, and ²³⁹Pu from inclusion of alternative values for the average total fragment kinetic energy is shown.