Evaluation and testing of double differential Fe(n,n') cross sections

Abstract

Analyses of integral experiments that include thick (>15 cm) iron regions have shown a consistent underprediction of neutron transmission. One explanation that has been offered is that the angular distributions of the inelastically scattered neutrons in the continuum in the current ENDF/B-V iron evaluation were assumed to be isotropic. In reality, these distributions are forward peaked, especially if the incident neutron energies (E/sub n/) are a few MeV greater than the continuum Q-value. The forward peaking also increases with increasing outgoing neutron energies (E/sub n/'), giving rise to correlated energy-angle distributions. In order to understand their effects on neutron penetration through iron, we generated such correlated distributions in a special update of the ENDF/B-V Mod-3 iron evaluation and re-analyzed an iron sphere problem. 9 refs., 2 figs