Decay of 172Hf to levels in 172Lu

The electron-capture decay of ¹⁷²Hf 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 γ-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 ¹⁷²Hf was constructed. It incorporates 17 transitions into 11 excited levels in ¹⁷²Lu and differs from previously proposed decay schemes. Several transitions previously attributed to ¹⁷²Hf 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 ¹⁷²Hf, measured E_γ, I_γ, I_x, γγ coin; deduced Q_EC. ¹⁷²Lu deduced levels J^π.