Neutron moderation with absorption

This lecture covers the process of neutron moderation with absorption, focusing on the interaction of neutrons with nuclei through elastic and inelastic scattering, radiative capture, and fission. It discusses the impact of resonances, the concept of lethargy, and the treatment of resonances in the context of neutron slowing down. The lecture also explores the practical implications of neutron migration during slowing down, Fermi age theory, and the space-dependent slowing down of neutrons. Various approximations, such as the narrow resonance and wide resonance infinite mass absorber approximations, are presented to simplify the complex neutron balance equations.