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HK: Fachverband Hadronen und Kerne

HK 6: Nuclear Structure and Dynamics I

HK 6.1: Invited Group Report

Monday, March 16, 2009, 14:00–14:30, H-ZO 40

Shell Structure in Neutron-Rich Nuclei around Z=20 — •Bogdan Fornal — Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland

It has been proven that the idea of a shell structure may be considered as an essential concept in understanding the atomic nucleus. According to that picture, the nucleons in a nucleus occupy well defined orbitals what implies that they move in a well defined average potential. The non-uniformities of the quantum states distribution in energy form the shells separated by the energy gaps - complete filling of the shells in nuclei along the stability valley occurs at magic numbers of nucleons: 2, 8, 20, 28, 50, 82, and 126. Recent investigations have shown, however, that magic numbers are not as universal as one might think. Examples of structural changes in nuclei with large neutron excess include the appearance of energy gap at N=32. The existence of this energy gap around Z=20 arises from the sizable energy spacing between the neutron p3/2 orbital and the higher lying p1/2 and f5/2 states. The studies of the location of single-particle states in 49Ca also pointed to a 2-MeV energy spacing between the two higher lying neutron orbitals p1/2 and f5/2. Such a finding could possibly have pointed to the presence of another subshell closure associated with the filling of the p1/2 orbital, i.e., at N = 34. However, the structure of very neutron-rich nuclei around Z=20 appeared to be very hard to reach. In the presentation, the status and perspectives of experimental investigations of the shell structure in exotic nuclei from the vicinity of N=34 will be discussed.