The effect of p-h corrections on the proton pairing vibrations at Z=50

Abstract

Recent experimental results from Cd( 3He, n)Sn reactions on a variety of Cd targets indicate that the proton pairing vibration lies at an excitation energy nearly 2 MeV below the value suggested by binding energy systematics. It is shown here that this large discrepancy, which is in contrast to the case of neutron pairing vibrations, may be explained by the effects of particle-hole (p-h) interactions which are large because of the Coulomb contribution. The p-h matrix elements are obtained empirically from observed p-h separations and also calculated theoretically for both Coulomb and nuclear contributions. These average empirical matrix elements from the Cd experiments give excellent agreement to the 2p-1h states in the 115In( 3He, n) experiment populated via L=0 transfers. The agreement in the latter case indicates a simple scaling of the interaction with the number of particles and holes.