PROTON AND LIGHT-ION INDUCED CHARGE-EXCHANGE REACTIONS IN NUCLEI

We study the different channels which contribute to the charge exchang e reactions of the type (He-3, t) (p, n) etc., in the region of excita tion of the delta resonance. We show that the shift of the delta peak in nuclei is due to a collaboration of many processes: delta excitatio n in the projectile, quasi-elastic collisions, virtual pion absorption and coherent pion production. The first three processes are responsib le for a considerable shift of strength but do not move the peak posit ion, while the addition of the coherent channel produces finally the s hift of the peak.