Mirror energy differences above the 0f7/2 shell: First γ-ray spectroscopy of the T = −2 nucleus 56Zn
A. Fernández, A. Jungclaus, P. Doornenbal, M. A. Bentley, S. M. Lenzi, D. Rudolph, F. Browne, M. L. Cortés, T. Koiwai, R. Taniuchi, V. Vaquero, K. Wimmer, T. Arıcı, N. Imai, N. Kitamura, B. Longfellow, R. Lozeva, B. Mauss, D. R. Napoli, M. Nııkura, X. Pereira-López, S. Pigliapoco, A. Poves, F. Recchia, P. Ruotsalainen, H. Sakuraï, S. Uthayakumaar, R. Wadsworth, R. Yajzey
Abstract
Excited states in 56Zn were populated following one-neutron removal from a 57Zn beam impinging on a Be target at intermediate energies in an experiment conducted at the Radioactive Isotope Beam Factory at RIKEN. Three γ rays were observed and tentatively assigned to the 6+→4+→2+→0+ yrast sequence. This turns 56Zn into the heaviest Tz=−2 nucleus in which excited states are known. The excitation-energy differences between these levels and the isobaric analogue states in the Tz=+2 mirror partner, 56Fe, are compared with large-scale shell-model calculations considering the full pf valence space and various isospin-breaking contributions. This comparison, together with an analysis of the mirror energy differences in the A=58, Tz=±1 pair 58Zn and 58Ni, provides valuable information with respect to the size of the monopole radial and the isovector multipole isospin-breaking terms in the region above doubly-magic 56Ni.