Excitation of A and N* resonances in isobaric charge-exchange reactions of heavy nuclei

摘要

We present a model for the study of the excitation of A(1232) and N*(1440) resonances in isobaric charge-exchange (~AZ,~A(Z ± 1)) reactions of heavy nuclei. Quasi-elastic and inelastic elementary processes contributing to the double differential cross sections of the reactions are described in terms of the exchange of virtual pions. The inelastic channel includes processes where the resonances are excited both in the target and in the projectile nucleus. We present results for reactions of ~(112)Sn and ~(124)Sn on different targets. Our results confirm that the position of the A peak is insensitive to targets with mass number A> 12, and show that the origin of the A peak shift towards low excitation energies, with respect to its position in reactions with a proton target, can be easily explained in terms of the superposition of the different excitation mechanisms contributing to the reaction.