The neutron optical potential

The nucleon optical model is described, with particular reference to the analysis of neutron scattering and reaction cross sections. The central, spin-orbit and isospin terms in the potential are defined and the results of phenomenological determinations of their parameters reviewed. The methods used to determine the asymmetry and isospin terms are described in detail. The optical potential as negative energies may be determined from the properties of the single-particle states and thus enables its behaviour at both positive and negative energies to be studied. Some of the methods used to calculate the optical potential from the nucleon-nucleon interaction are described and the results compared with the phenomenological potential. The coupled-channels formalism enables both elastic and inelastic scattering from collective nuclei to be analysed simultaneously. Some analyses made in this way are reviewed, together with similar analyses of charge-exchange isobaric analogue state reactions.