Isovector effective interactions. An empirical approach

In the last few years new data has been used to test more accurately models of the effective interactions which drive nucleon-nucleus scattering processes. At intermediate energies (E>100 MeV) where the impulse approximation is well justified, the effective interaction is identified with the free nucleon-nucleon t-matrix. At lower energies (E<100 MeV) nuclear medium effects become important and these effects need to be incorporated in the effective interaction via the G-matrix formalism. Charge exchange reactions uniquely select the isovector terms of the effective interaction and may be used to test the different models with data. The isovector terms may be empirically evaluated from a comparison of neutron and proton elastic scattering. If done in a model independent analysis, it provides a unique way to compare empirical and theoretical results. (author). 11 figs., 35 refs