The electron-capture decay of ${}_{}{}^{172}{}_{}{}^{}\mathrm{Hf}$ was investigated. Single and coincidence measurements were made by using germanium x-ray detectors. In addition, a Si(Li) detector was used to study the low-energy portion, ≲ 60 keV, of the $\gamma$-ray spectrum. These results were then combined with available conversion-electron data which had been obtained with a magnetic spectrometer. From this information, a decay scheme for ${}_{}{}^{172}{}_{}{}^{}\mathrm{Hf}$ was constructed. It incorporates 17 transitions into 11 excited levels in ${}_{}{}^{172}{}_{}{}^{}\mathrm{Lu}$ and differs from previously proposed decay schemes. Several transitions previously attributed to ${}_{}{}^{172}{}_{}{}^{}\mathrm{Hf}$ decay were not observed in the present study. The electron-capture decay energy was deduced from measured $K$ x-ray intensities and the level scheme to be 350±50 keV.

RADIOACTIVITY ${}_{}{}^{172}{}_{}{}^{}\mathrm{Hf}$, measured $E_{\gamma }$, $I_{\gamma }$, $I_x$, $\gamma \gamma$ coin; deduced $Q_{\mathrm{EC}}$. ${}_{}{}^{172}{}_{}{}^{}\mathrm{Lu}$ deduced levels $J^{\pi }$.

• Received 11 June 1979

DOI:https://doi.org/10.1103/PhysRevC.20.1902