Structure of As83, As85, and As87: From semimagicity to γ softness
Résumé
The structure of As83, As85, and As87 have been studied in fusion-fission reaction U238+Be9. Fission fragments were identified in mass and atomic number using the VAMOS++ spectrometer and the coincident γ rays were detected in the γ-ray tracking array AGATA. New transitions in As83 and As85 are reported and placed in the level schemes. A level scheme of the excited states in As87 is proposed for the first time. The data are interpreted in frame of large-scale shell-model calculations, SU3 symmetries, and beyond mean-field frameworks. A spherical regime at magic number N=50 is predicted and the location of the proton g9/2 orbital is proposed for the first time. Development of collectivity in a prolate deformed, γ-soft regime in the open shell cases As85 and As87, most neutron-rich isotopes beyond N=50, is concluded. Data and theoretical calculations give confidence to a relatively high extrapolated excitation energy about 4 MeV of the 9/2+ state in Cu79, one proton above Ni78.
| Origine | Fichiers produits par l'(les) auteur(s) |
|---|
