Nucleon correlations and the structure of 7130Zn41

The structure of Zn-71 was investigated by one-neutron transfer and heavy-ion induced complex (deep-inelastic) reactions using the GRETINA-CHICO2 and the Gammasphere setups, respectively. The observed inversion between the 9/2(+) and 1/2(-) states is explained in terms of the role of neutron pairing correlations. Non-collective sequences of levels were delineated above the 9/2+ isomeric state. These are interpreted as being associated with a modest oblate deformation in the framework of Monte-Carlo shell-model calculations carried out with the A3DA-m Hamiltonian in the pfg(9/2)d(5/2) valence space. Similarities with the structure of Ni-68(28)40 were observed and the shape-coexistence mechanism in the N = 40 region of neutron-rich nuclei is discussed in terms of the so-called Type-IIshell evolution, with an emphasis on proton-neutron correlations between valence nucleons, especially those involving the shape-driving g(9/2) neutron orbital. (C) 2017 The Author(s). Published by Elsevier B.V.