# Etude des dérives monopolaires neutron au-delà du $^{78}$Ni par spectroscopie gamma avec BEDO à ALTO et AGATA au GANIL

Abstract : Nuclear spherical shell structure evolves towards more and more exotic regions of the nuclear chart. Therefore, conventional magic numbers (2, 8, 20, 28, 50, 82, 126) can disappear while new ones appear.  The evolution of gaps between single-particle states far from stability has essentially two origins : monopole drift and the collectivity enhancement. The monopole drifts are mostly coming from neutron-proton interaction (spin-isospin term of the nuclear interaction). In this thesis, we focused on the study of N=51 isotones and in particular 83Ge, the closest to 79Ni that can be studied nowadays by detailled γ-spectroscopy. For this purpose, two complementary experiments were performed. A first experiment, at GANIL with AGATA, VAMOS and the OUPS plunger device allowed us to measure lifetime of Yrast excited states in the 238U(9Be,f) reaction products. A second experiment for the study of β-delayed γ-spectroscopy of 83Ge was performed in order to populate non-Yrast states so that has an overview of the spectroscopy of 83Ge.The complementarity of these two experiments allowed highlighting for the first time an intruder state above the N=50 gap in 83Ge and thus, it adds information about the evolution of the νg9/2νd5/2 gap corresponding to the N=50 shell closure.A detailed analysis of both experiments is presented in this manuscript. In addition, a comparison to a semi-microscopic core-particle model is performed.
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Submitted on : Wednesday, July 25, 2018 - 10:17:16 AM
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• HAL Id : tel-01848718, version 1

### Citation

Clément Delafosse. Etude des dérives monopolaires neutron au-delà du $^{78}$Ni par spectroscopie gamma avec BEDO à ALTO et AGATA au GANIL. Physique Nucléaire Expérimentale [nucl-ex]. Université Paris-Saclay, 2018. Français. ⟨NNT : 2018SACLS199⟩. ⟨tel-01848718⟩

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