ROLE OF THE G9 2 NEUTRON ORBITAL IN THE STRUCTURE OF ZN-65/

Measurements of gamma-ray singles and gammagamma-coincidence spectra, gamma-ray angular distributions, and Doppler shift attenuation have be en made, following the reaction Cu-63(He-4,pn) Zn-65 at 30 MeV. The le vel scheme has been confirmed up to 5773 keV. The spins and parties of the three states at 3227.6, 3785.7, and 4938.0 keV, hitherto uncertai n or unknown, are found to be 17/2+, 17/2+, and 21/2+, respectively. T he mean lives for these states, for which there is no information avai lable in the literature, have been estimated, and the deduced B(E2) va lues for the 4938.0 --> 3227.6 (21/2 1 --> 17/2+), 3227.6 --> 2053.5 ( 17/2+ --> 13/2+), and 3785.7 --> 2053.5 (17/2+ --> 13/2+) keV transiti ons are all found to be strongly enhanced with respect to the Weisskop f single-particle estimates indicating collectivity in the structure o f the concerned states. Evidence is presented in favor of the interpre tation of the positive parity states in Zn-65 with J(pi) value 9/2+ to 21/2+, as arising from the weak coupling of a g9/2 neutron to the qua drupole excitations of the Zn-64 core.