Decay ofZn63

Abstract

The decay of 38.4-min ${\mathrm{Zn}}^{63}$ has been investigated using scintillation and beta spectrometer techniques. 84% of the decays are to the ${\mathrm{Cu}}^{63}$ ground state. Gamma rays having energies of 0.67, 0.96, and 1.42 Mev are present with intensities of 9.0, 6.7, and 0.9% of the ${\beta }^{+}$ transitions. Low intensity gamma rays (<0.2%) were observed at energies of 1.55, 1.83, 2.04, 2.34, 2.55, 2.77, and 3.10 Mev. Coincidence measurements established positron feeding of the ${\mathrm{Cu}}^{63}$ levels at 0.67, 0.96, and 1.42 Mev but no $\gamma -\gamma$ coincidences were observed. Internal conversion coefficients of the 0.67- and 0.96-Mev gamma rays are in agreement with predominantly $M1\mathrm{}$ assignments to both transitions. A decay scheme is presented which differs significantly from that previously reported. It is inferred that the spin of ${\mathrm{Zn}}^{63}$ is ${\frac{3}{2}}^{-}$. $M1\mathrm{}$ and $E2\mathrm{}$ transition probabilities between the various levels of ${\mathrm{Cu}}^{63}$ and ${\mathrm{Cu}}^{65}$ are discussed in terms of the "center-of-gravity" model for states in these nuclei. Both agreements and disagreements with the model predictions are observed.