Multiple Neutron Interactions in Resonant Foils

Experiments on resonance neutron capture, scatter, or fission are often analyzed with thin-foil approximations, but for reasons of intensity are better performed with foils of intermediate thickness. For aid in analyzing the resulting corrections, the probability is calculated that a neutron at normal incidence on a foil will be scattered and undergo a second interaction in the foil. This probability is averaged over a resonance and is compared to the probability of a first interaction. The extension to multiple interactions is considered. An important effect is the change in cross section because of energy loss in elastic scattering. The Doppler broadening of resonances and the effect of potential scattering are also included. The application to the area analysis of self-indication experiments is emphasized. This general case includes several more restricted cases with resonant detectors and with nonresonant detectors.