Shell evolution beyond Z=28 and N=50: Spectroscopy of 81,82,83,84Zn

We report on the measurement of new low-lying states in the neutron-rich Zn-81,Zn-82,Zn-83,Zn-84 nuclei via inbeam gamma-ray spectroscopy. These include the 4(1)(+)-> 2(1)(+) transition in Zn-82, the 2(1)(+) -> 0(g.s.)(+) and 4(1)(+)-> 2(1)(+) transitions in Zn-84, and low-lying states in Zn-81,Zn-83 were observed for the first time. The reduced E(2(1)(+)) energies and increased E(4(1)(+))/ E(2(1)(+)) ratios at N= 52, 54 compared to those in Zn-80 attest that the magicity is confined to the neutron number N= 50only. The deduced level schemes are compared to three state-of-the-art shell model calculations and a good agreement is observed with all three calculations. The newly observed 2(+) and 4(+) levels in Zn-84 suggest the onset of deformation towards heavier Zn isotopes, which has been incorporated by taking into account the upper sdgorbitals in the Ni78-II and the PFSDG-U models. (C) 2017 The Authors. Published by Elsevier B.V.