Decay of a New Isotope:Cu69

Abstract

Sources of ${\mathrm{Cu}}^{69}$ have been produced by $\gamma -p$ reactions in Zn (enriched to 78.3% ${\mathrm{Zn}}^{70}$) and their decay has been studied with scintillation and semiconductor detectors. The half-life of ${\mathrm{Cu}}^{69}$ has been determined to be 3.0±0.1 min. Seventy-nine percent of the decay is by direct beta decay to the ground state of ${\mathrm{Zn}}^{69}$ ($E_0=2.48\mathrm{}\pm 0.07$ MeV, $logft=5.1\mathrm{}$). The remaining decay modes exhibit a complex spectrum for which a level scheme has been established. The proposed ${\mathrm{Zn}}^{69}$ levels that are fed by the ${\mathrm{Cu}}^{69}$ decay are at 0.5307, 0.8340, 1.0065, 1.1795, 1.428, 1.825, and 2.026 MeV. Other suggested but more tentative levels are at 0.615, 2.17, and 2.4 MeV. Of the beta-decay modes, those to the 0.5307- and 0.615-MeV levels have the highest $log\mathrm{ft}$ values, namley ∼6.7 and 6.8, respectively. The $log\mathrm{ft}$ values of the other branches are smaller than 5.7 and all indicate allowed beta decay.