Study of neutron-rich nuclei near the doubly magic nuclei of ¹³²Sn

The evolution of nuclear structure in the vicinity of the doubly magic nuclei ¹³²Sn will be discussed in this work, through the spectroscopy of ¹³⁶₅₁Sb₈₅, ¹³⁶₅₀Sn₈₆ and ¹³⁸₅₀Sn₈₈ isotopes. Several Sb and Sn known isotopes beyond the Z = 50 and N = 82 shell closures will be briefly presented in the first chapter, as well as some of the problems arising from the current shell-model description of the nuclei in this region. The reader will also find in the same chapter a brief description of the most important tools needed to understand such calculations. Excited states of ¹³⁶Sb have been populated at the Institut Laue-Langevin (Grenoble) through thermal neutron-induced fission on a ²⁴¹Pu target. The fission fragments produced were separated with the Lohengrin mass spectrometer. Delayed conversion electrons and γ-rays from ¹³⁶Sb were measured and confirmed the previously proposed schemed. A new 31(7) ns isomer has been measured and assigned to the 4^- state. Details of the experiment and analysis are presented in the first part. The second part is devoted to the ^136;138Sn isotopes, produced via in-flight fission of ²³⁸U on a ⁹Be target at the RIBF of the RIKEN (Tokyo). The mass separators BigRIPS and ZDS allowed separation and identification of the produced fragments, before implantation in the highly segmented silicon detector WAS3ABi surrounded by the EURICA germanium array. The first energy measurement of the 6⁺ → 4⁺, 4⁺ → 2⁺ and 2⁺ → 0⁺ transitions has been performed for each of the ^136;138Sn isotopes, as well as 46(7) and 219(58) ns half-lives for the 6⁺ states of the ¹³⁶Sn and ¹³⁸Sn respectively. (author)