The Energy Spectrum of Prompt Neutrons from the Fission of Uranium-235 by 0.40-MeV Neutrons

The prompt fission neutron energy spectrum of ²³⁵ U was measured at an incident neutron energy of 0.40 MeV with two samples of different thickness. The data were corrected for flux attenuation in the sample material and for effects due to the energy change of the out-going fission neutrons by inelastic scattering and secondary fission processes. After applying these shape corrections, an average fission neutron energy of 2.06 ± 0.05 MeV was obtained using the Watt and the Maxwellian functions for the energy distribution of the fission neutrons. This result has been compared with the presently available results of other works.