Neutron rich nuclei between Ca (Z=20) and Ni (Z=28) point to an evolving shell structure with respect to the neutron shell gaps established for stable and proton-rich nuclei at N=28 and N=40. There is now strong evidence for an additional shell gap at N=32 shell for Ca and Ti isotopes, a possible gap at N=34 for Ca isotopes, and the disappearance of the N=40 shell gap below Ni. In order to characterize this changing structure, the experimental investigations have required the utilization of both the coupled cyclotron facility (NSCL) at Michigan State University and the ATLAS facility at Argonne National Laboratory. The data taken at both facilities is complementary and taken together provide as complete a picture as is currently obtainable using the experimental tools presently available. The experimental techniques utilized to perform these investigations along with present evidence for this change in shell structure will be presented.
Argonne Physics Division Colloquium Schedule