New Isomer:Cu68m

Abstract

Irradiation of natural Zn, Ga, and enriched ${}_{}{}^{68}{}_{}{}^{}\mathrm{Zn}$ with 14.7-MeV neutrons was found to produce a new radioactivity with a half-life of 3.8±0.1 min which was assigned as an isomer of ${}_{}{}^{68}{}_{}{}^{}\mathrm{Cu}$. The energies and relative intensities of those $\gamma$ rays associated with the decay of 3.8-min ${}_{}{}^{68m}{}_{}{}^{}\mathrm{Cu}$ are: 0.085±0.001, 0.110±0.001, 0.153±0.001, 0.525±0.001, 0.577±0.002, 0.635±0.001, 1.078±0.002, 1.260±0.002, and 1.338±0.002 MeV, with relative intensities of 94.8±06., 25.7±1.0, 6.1±0.8, 100.00, ∼2.4, 15.8 (some summing of 0.525-0.110 MeV), 83.3±1.3, 14.1±2.0, and 11.8±3.0, respectively. A maximum $\beta$-ray endpoint energy of 4.6±0.1 MeV was observed. Coincidence measurements of the 0.085- and 0.525-MeV, $\gamma$ rays indicate that these $\gamma$ rays are associated with an isomeric transition to the 30-sec ${}_{}{}^{68}{}_{}{}^{}\mathrm{Cu}$ ground state.