Nuclear Seminar

Interplay between spherical and deformed states in the neutron-deficient Pb-isotopes

Dr. Veerle Hellemans
University of Ghent, Belgium

Monday, October 29, 2007   4:00 p.m.   NSH 124
(Refreshments served prior to seminar in NSH 124)

The neutron-deficient Pb-isotopes (Z=82) provide a unique laboratory to study the phenomenon of shape coexistence in atomic nuclei.  Whereas shell-model excitations dominate the spectrum near the doubly closed-shell nucleus ²⁰⁸Pb, collective modes of motion govern the properties of the Pb-isotopes in the vicinity of neutron midshell.  Microscopically, the appearance of the collective bands can be related to 2p-2h and 4p-4h proton excitations across the closed Z=82 proton shell.  The interacting boson model (IBM), a symmetry-based truncation of the nuclear shell model, provides a framework in which the model space for the Pb-isotopes (including 0p-0h, 2p-2h, and 4p-4h proton excitations) becomes tractable.  In our IBM calculations including configuration mixing, we focused on the ^186-196Pb –isotopes.  The results of these calculations will be extensively discussed and confronted with recent experimental data.