Modified Methods of Neutron Cross-Section Calculations

Abstract

Conventional formulas of the neutron cross sections based on the statistical model are modified so as to keep equality between the total cross section and the sum of the partial cross sections by taking into account the effects of the cascade process ac-companied by the emission of γ-rays from the compound nuclear states, and of other processes which compete with the neutron scattering and capture. The modifications are applied to the cross-section formulas with width-fluctuation correction and resonance-resonance interference, according to the statistical distribution law of the level widths and spacings, respectively. Examples of calculations are shown for ²³⁸U, ¹⁰⁹Ag, ¹⁰³Rh and ⁹⁰Sr. Discussions are given concerning the contributions of the cascade process, the competing processes, the width-fluctuation and resonance-interference effects.