HIGH-SPIN STATES IN ZN-63

High spin states of Zn-63 isotope have been populated by Cr-50(O-16, 2 pn) reaction at a beam energy of 75 MeV. A total of 37 gamma rays and 18 energy levels have been placed in the proposed level scheme, extend ing it up to an excitation energy of 9776 keV. Positive and negative p arity states up to I = 23/2 and 31/2, respectively, are found to be po pulated. A positive parity unfavored band and a negative parity band h ave been identified. The structure of this nucleus has been investigat ed in the framework of interacting boson-fermion model, incorporating both the quadrupole and the octupole excitations of the even-even Zn-6 2 core. The structure of the positive parity yrast band is described i n terms of a weak coupling of the g(9/2) neutron motion to the multiph onon excitations of the even-even core. Some of the high spin negative parity states observed in the experimental spectrum cannot be describ ed within the framework of the present model. One of the possible reas ons may be that these states have large contributions from noncollecti ve two-quasiparticle-type excitations. Experimental branching ratios o f some of the transitions are compared with the results of our calcula tion. [S0556-2813(98)01604-5].