southwestern boundary of the N=40 island of inversion: First study of low-lying bound excited states in v 59 and v 61

Abstract

The low-lying level structure of V59 and V61 was investigated for the first time. The neutron knockout reaction and inelastic proton scattering were applied for V61 while the neutron knock-out reaction provided the data for V59. Four and five new transitions were determined for V59 and V61, respectively. Based on the comparison to our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja (LNPS) interaction, three of the observed γ rays for each isotope could be placed in the level scheme and assigned to the decay of the first 11/2- and 9/2- levels. The (p,p′) excitation cross sections for V61 were analyzed by the coupled-channels formalism assuming quadrupole plus hexadecapole deformations. Due to the role of the hexadecapole deformation, V61 could not be unambiguously placed on the island of inversion. © 2022 American Physical Society.