E 2 collectivity in shell-model calculations for odd-mass nuclei near 132 Sn

Shell-model calculations for 127,129 In and 129,131 Sb are presented, and interpreted in the context of the particle-core coupling scheme, wherein proton g 9/2 holes or g 7/2 particles are added to semimagic 128,130 Sn cores. These results indicate that the particle-core coupling scheme is appropriate for the Sb isotopes, whilst less so for the In isotopes. B (E2) excitation strengths are also calculated, and show evidence of enhanced collectivity in both Sb isotopes, especially 131 Sb. This observation suggests that 131 Sb would be an excellent case for an experimental study seeking to investigate the early onset of collectivity near 132 Sn.