Fast-timing study of Ga81 from the β decay of Zn81

The β− decay of Zn81 to the neutron magic N=50 nucleus Ga81, with only three valence protons with respect to Ni78, was investigated. The study was performed at the ISOLDE facility at CERN by means of γ spectroscopy. The Zn81 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 Zn81 provides 47 new levels and 70 new transitions in Ga81. The β−n decay of Zn81 was observed and a new decay scheme into the odd-odd Ga80 nucleus was established. The half-lives of the first and second excited states of Ga81 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 Ga81 is interpreted in terms of the coupling of the three valence protons outside the doubly magic Ni78 core.3 MoreReceived 11 March 2020Revised 4 June 2020Accepted 24 June 2020DOI:https://doi.org/10.1103/PhysRevC.102.014329©2020 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeta decayLifetimes & widthsNuclear structure & decaysProperties59 ≤ A ≤ 89TechniquesRadiation detectorsRadioactive beamsNuclear Physics