Statistical Model Calculations of Iron-56 Neutron Cross Sections

Calculations are presented of total cross sections for the following five neutron-induced processes on ⁵⁶Fe: (n,γ), (n,n’), (n,p), (n,2n), and (n,np), at neutron energies ranging from 10 keV to 18 MeV, depending on the process. The calculations were carried out using the ABACUS-NEARREX code modified by the addition of a subroutine which modeled statistically the final-state level distributions whenever experimental data were lacking. The statistical parameters for the level density formula used in this subroutine were obtained by normalizing to experimental level densities in ⁵⁶Fe and ⁵⁶Mn, and to low energy (7 MeV) (n,n’) and (n,p) cross sections. The parameters so derived are in good agreement with those derived from the nuclear shell model. In general, the agreement between the calculations and the experimental cross sections for the five processes enumerated is excellent. It appears clear that the compound statistical model is very good for predicting total reaction rates of this type.