Proton-Neutron Interaction near Closed Shells

Abstract

Odd-odd nuclei around double shell closures are a direct source of information on the proton-neutron interaction between valence nucleons. We have performed shell-model calculations for doubly odd nuclei close to ${}^{208}$Pb, ${}^{132}$Sn and ${}^{100}$Sn using realistic effective interactions derived from the CD-Bonn nucleon-nucleon potential. The calculated results are compared with the available experimental data, attention being focused on particle-hole and particle-particle multiplets. While a good agreement is obtained for all the nuclei considered, a detailed analysis of the matrix elements of the effective interaction shows that a stronger core-polarization contribution seems to be needed in the particle-particle case.

Comments: 8 pages, 6 figures, Proccedings of the International Conference "Nuclear Structure and Related Topics", Dubna, Russia, September 2-6, 2003, to be published in Yadernaia Fizika (Physics of Atomic Nuclei)