Séminaire DRS/Phys. Nucl - "Shell structure and shape coexistence at N=50 studied by in-beam and decay spectroscopy" A. Gottardo

vendredi 11 mars 2016, 10:30 → 12:00 Europe/Paris

Batiment 27

Shell structure and shape coexistence at N=50 studied by in-beam and decay spectroscopy The origin of spin-orbit shell closures is still an open question in nuclear physics. The N=50 is no exception and two-body forces seem not able to explain the experimental evidence gathered so far. A campaign for the study of the N=50 shell closure near 78Ni has started at the radioactive beam facility ALTO. New results on beta-delayed gamma and electron spectroscopy on 80,83Ge will be presented. In 80Ge, the presence of a 0+ as first excited state suggests shape coexistence in this region, and possibly in 78Ni. In 83Ge, the reconstructed level scheme provides indication on the evolution of effective single-particle energies beyond N=50. The need of identifying single-particle states implies the necessity of distinguishing them from core-coupled states. This can be accomplished by measuring their lifetime. To this purpose, an experiment was performed at GANIL using the AGATA-VAMOS setup to measure lifetimes in 82,83Ge and nuclei around, produced via fission reactions. Preliminary results will be shown and discussed in relation to the N=50 shell gap and the correlated monopole behaviour in this exotic region.