New evidence for deformation in Zn-73

The beta decay of Cu-73 to levels in Zn-73 has been studied. The Cu-73 nucl ides were produced by fragmentation of Ge-76 projectiles having energies of 70 MeV/nucleon in a 202 mg/cm(2) thick Be-9 target. beta and gamma singles , beta-gamma and gamma-gamma coincidence data were collected and used to co nstruct the low-energy level scheme of Zn-73. New spin-parity assignments h ave been deduced for some excited states in Zn-73 based on measured beta de cay branching ratios and systematics of other N=43 isotones. A 195-keV tran sition was identified in Zn-73 with a half-life of 13.0(2) ms, a value seve ral orders of magnitude shorter than previously reported, and is consistent with an M2 multipolarity. The low-energy level structure of Zn-73 is shown to be consistent with particle-triaxial rotor model calculations employing a ground state quadrupole deformation with beta(2)=0.2. [S0556-2813(98)005 12-3].