Structure of the N=50 As, Ge, Ga nuclei

Abstract The level structuresof the N = 50 83 As, 82 Ge, and 81 Ga isotoneshave been investigated by means of multi-nucleon transfer reactions. A first experiment was performed with the CLARA–PRISMA setup to identify these nuclei. A second experiment was carried out with the GASP array in order to deduce the γ -ray coincidence information. The results obtained on the high-spin states of such nuclei are used to test the stability of the N = 50 shell closure in the region of 78 Ni ( Z = 28 ). The comparison of the experimental level schemes with the shell-modelcalculations yields an N = 50 energy gap value of 4.7(3) MeV at Z = 28 . This value, in a good agreement with the prediction of the finite-range liquid-drop model as well as with the recent large-scale shell modelcalculations, does not support a weakening of the N = 50 shell gap down to Z = 28 .