New evidence for deformation in ⁷³Zn

The β decay of ⁷³Cu to levels in ⁷³Zn has been studied. The ⁷³Cu nuclides were produced by fragmentation of ⁷⁶Ge projectiles having energies of 70 MeV/nucleon in a 202 mg/cm² thick ⁹Be target. β and γ singles, β-γ and γ-γ coincidence data were collected and used to construct the low-energy level scheme of ⁷³Zn. New spin-parity assignments have been deduced for some excited states in ⁷³Zn based on measured β decay branching ratios and systematics of other N=43 isotones. A 195-keV transition was identified in ⁷³Zn with a half-life of 13.0(2) ms, a value several orders of magnitude shorter than previously reported, and is consistent with an M2 multipolarity. The low-energy level structure of ⁷³Zn is shown to be consistent with particle-triaxial rotor model calculations employing a ground state quadrupole deformation with β₂=0.2.