Fission-neutron spectra measurements of 235U, 239Pu and 252Cf

Abstract

The fission-neutron spectra of 835U, 239Pu and 252Cf were experimentally studied using proton-recoil proportional counters and 3He-semiconductor-sandwich-spectrometers. The spectra and the average energies as determined with both techniques agree within the experimental errors. The spectra are described quite well by Maxwellian distributions. The average energies deduced from the Maxwellian fits are consistent with most previously reported microscopic results and amount to 1·956 (2·020), 2·136 (2·075) and 2·155 (2·130) MeV for 235U, 239Pu and 252Cf, the numbers in brackets refer to the 3He-spectrometer values.