Medium-Spin Structure of the N = 28 Isotones 54Fe and 55Co

Abstract

Excited states in the N = 28 isotones 54Fe and 55Co were populated in the bombardment of 54Fe with 3He ions. The subsequent de-excitation was studied using experimental in-beam techniques including γ-γ coincidences and γ-ray angular distributions. A number of previously unobserved levels were discovered in 54Fe and a new high-spin complex was assigned to 55Co. Self-consistent Hartree-Fock calculations were performed to elucidate the underlying nuclear structures. It was found that the ground-state shapes of 54Fe and 55Co correspond to deformation parameters β2 = +0.03 and +0.02, respectively. Shell-model arguments and calculations were used to assign configurations to the excited states.