The Sequential Transfer Mechanisms in (p,n) Reactions
The first order distorted wave Born approximation (DWBA) has provided a good description for many nuclear reactions. In the study of charge exchange reactions such as (3He,t) and (p,n) one would initially expect to understand these processes in terms of an effective two-body charge exchange potential which acts between the incident projectile and the target nucleons. For the low spin transitions, especially the analogue state transitions, one could approximately explain1,2 the data in terms of effective nucleon-nucleon force strengths. These successes were tempered by the failure of the theory to account for the excitation strength3–5 of the higher spin states such as the 6+ and 8+ states. (The strength of the effective interaction was found to be about an order of magnitude larger for the 6+ state than for the 0+ analogue state.) These results were for cases where simple shell model configurations such as (π f7/2) (v f7/2)−1 and (π g9/2) (v g9/2)‒1 could be used. Schaeffer6 has shown that exchange effects cannot remove the high spin renormalization difficulty although the corrections were significant and in the right direction.