Quadrupole moment of the 6- isomeric state in 66Cu: Interplay between different nuclear deformation driving forces

We have measured the spectroscopic quadrupole moment of the 6(-) isomeric state in Cu-66 to be vertical bar Q(s)vertical bar = 18.6(12) efm(2). This state results from a weak coupling of the pi p(3/2) and the nu g(9/2) orbitals, which lead to sizable deformation at oblate and prolate shapes, correspondingly, in the Ni-68 region. The interplay between these two different deformation-driving orbitals is observed at N = 37 for the 6(-) state resulting in a most probable oblate shape. (C) 2010 Elsevier B.V. All rights reserved.