A new parametrization for prompt fission neutron spectra

For some applications it is useful to have neutron spectral information in a simple analytical form. Although experimental spectra are often approximated by Maxwellian expressions, a better agreement is given with a sum of Maxwellian distributions. A statistical model is suggested with the temperature continuum for the center-of-mass energy spectrum given by an equation including such a summation. The formula was used to analyze data from the fission of 235U and 239Pu induced by 0.53 MeV neutrons and the 252Cf (spontaneous fission) spectrum. The parameters fitted with the formula and the theoretical parameters and fit values are tabulated. (UK)