Verification of the Los Alamos theory of the prompt fission neutron spectrum

Two new 252Cf spontaneous fission experiments have been performed since our previous work on this nucleus, namely, the microscopic measurement of the 252Cf(sf) spectrum by Poenitz and Tamura and the integral measurements of 12 reactions by Kobayashi et al. Least-squares adjustments of the Los Alamos exact spectrum and a Maxwellian spectrum fit to the Poenitz and Tamura experiment are described elsewhere. The final values of the two parameters of adjustment are, respectively, a = (A/9.15) MeVπ1 for the nuclear level density and T/sub M/ = 1.429 MeV for the Maxwellian temperature. The chi/sub min/2 value for the best-fit Los Alamos exact spectrum is a factor approx. 2.2 better than that of the best-fit Maxwellian spectrum. In fact, the ratios of the Los Alamos exact spectrum and the experimental spectrum to the Maxwellian spectrum, clearly indicate that the Los Alamos spectrum is in uniformly better agreement with the experiment. Using these two spectra, we have calculated 10 of the 12 integral cross sections measured by Kobayashi et al. for which ENDF/B-V microscopic cross sections exist, together with the normalizing 27Al(n,α) integral cross section. Our calculated results are compared to the experiment. We conclude on the basis of the evidence summarized here that the Los Alamos (Madland-Nix) exact energy-dependent cross-section calculation is the preferred prompt fission neutron spectrum representation