Pasqualato, Giorgia (2017) Investigation of shape coexistence in 60Zn by using the gamma-ray spectrometer GALILEO at the Legnaro National Laboratories. [Magistrali biennali]
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This thesis describes the results of a fusion-evaporation experiment performed at the Legnaro National Laboratories, using the gamma-ray spectrometer GALILEO, that was recently installed at the laboratory, combined with the ancillary detectors EUCLIDES and Neutron Wall, for the light-charged particle and neutron detection, respectively. The experiment aims at the measurement of non-yrast states in the neutron-deficient, N=Z, 60Zn nucleus. The nucleus is located at the lower corner in the region of transitional nuclei, that goes from the spherical 56Ni to the prolate 80Zr. The change in the nuclear shape is a consequence of the shell evolution, that is driven by the nuclear residual interaction between protons and neutrons. Gamma-ray spectroscopy is a great experimental tool to investigate the structure of such nuclei that provides essential information to model the nuclear force. By comparing the experimental results with the predictions of the theoretical models, the shape of a nucleus can be derived. From the analysis of our data set, we confirm the existence of the ground state band in 60Zn, up to the 8+ state. Large scale shell model (LSSM) and energy density functional (EDF) calculations, are carried out for 60Zn, and are in agreement with the experimental results for the ground state band. Furthermore, we observe a weak transition in a alpha-gated gamma-gamma matrix, that could correspond to the decay of a second 2+ state, predicted by LSSM calculation at 3.2 MeV, to the first 2+ state. However, this state is predicted at a lower energy by the EDF calculations. Eventually, because of the low statistics and the discrepant theoretical predictions, no firm conclusion can be drawn about the intrinsic shape of the 60Zn nucleus, at this level.
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