Fast-timing study of 81Ga from the β decay of 81Zn
Abstract
The β- decay of 81Zn to the neutron magic N=50 nucleus 81Ga, with only three valence protons with respect to 78Ni, was investigated. The study was performed at the ISOLDE facility at CERN by means of γ spectroscopy. The 81Zn half-life was determined to be T1/2=290(4) ms while the β-delayed neutron emission probability was measured as Pn=23(4)\%. The analysis of the β-gated γ-ray singles and γ-γ coincidences from the decay of 81Zn provides 47 new levels and 70 new transitions in 81Ga. The β-n decay of 81Zn was observed and a new decay scheme into the odd-odd 80Ga nucleus was established. The half-lives of the first and second excited states of 81Ga were measured via the fast-timing method using LaBr3(Ce) detectors. The level scheme and transition rates are compared to large-scale shell-model calculations. The low-lying structure of 81Ga is interpreted in terms of the coupling of the three valence protons outside the doubly-magic 78Ni core.