Excitation of Nuclear Levels via Pion Photoproduction and Pion Scattering.

The inelastic scattering of mesons on nuclei with the excitation of bound or quasi-bound states is a natural probe for the study of transition densities in parallel with the investigation of charge transition densities in inelastic electron scattering. The pioneering approach of linking various intermediate energy reaction cross sections to those of (e,e') reactions is now applied to the inelastic pion scattering. A separable fixed scatterer pion-nucleon interaction and the distorted wave impulse approximation is used for medium energy pion inelastic scattering and charge exchange. An optical potential based on the pion-nucleon interaction adopted in this work has been shown previously to provide good fits to pion-nucleus elastic scattering. The nuclear level transition densities are first obtained from experimental (e,e') results using the Helm model. The parameters obtained herefrom are used in the calculation of the cross sections of (e,e') reactions for a number of nuclei. In this way, theoretical interpretations of the experimental data will become available which are based on the results of (e,e') data rather than on purely theoretical models.