Nucleon-Nucleus Collisions and Intermediate Structure

Abstract

This chapter is devoted to the topic of resonances in nuclear reactions and, in particular, to the topic of intermediate resonance structure in the energy dependence of the nuclear cross section (FKL 67, KRY 68). This latter topic is of considerable current interest, while the former topic has been discussed since the work of Breit and Wigner (BW 36) in the 1930’s. The basis for the description of resonance reactions presented here will be that of the optical model plus residual interactions. Specifically, the reaction dynamics in a nucleon-nucleus scattering will be discussed from the viewpoint of an independent particle picture plus residual interactions. The “black box” description of the nuclear reaction amplitude in terms of resonance parameters will be abandoned in the hope that simple excitations of the target-incident-nucleon system are observable as some type of structure in the reaction amplitude. It is then hoped that the various parameters describing this structure can be calculated in terms of the interaction between the incident nucleon and the target nucleons. A likely candidate for such a calculable structure is the experimental phenomenon called intermediate structure.