Decay Scheme of the 23-minCu60with High-Resolution Ge(Li) Detectors

The decay of the 23-min ${}_{}{}^{60}{}_{}{}^{}\mathrm{Cu}$ has been investigated with the use of Ge(Li) and NaI(Tl) $\gamma$-ray detectors. Coincidence relationships among the $\gamma$ rays were established in $\gamma -\gamma$ coincidence experiments. It was concluded that the decay of the 23-min ${}_{}{}^{60}{}_{}{}^{}\mathrm{Cu}$ populates levels at 1332.4, 2158.8, 2284.4, 2505.6, 2626.0, 3124.2, 3194.2, 3269.3, 3393.4, 3735.8, 4003.4, 4022, 4078.6, 4317, 4494, 4548, and 4573 keV. A number of transitions not reported previously have been observed and assigned in the decay scheme. The levels populated in the proposed decay scheme have been previously reported from studies of the ${}_{}{}^{60}{}_{}{}^{}\mathrm{Cu}$ decay and from nuclear-reaction spectroscopic studies. From $log\mathrm{ft}$ values and $\gamma$-ray information, many spin assignments have been made. The levels are compared with the results of recent calculations on current models for the nucleus. No evidence is found for a $0^{+}$ state at about 2.9 MeV as predicted by the effective-interaction calculations based on the shell model.