The half-life of ${}_{}{}^{169}{}_{}{}^{}\mathrm{Hf}$ was found to be 3.26 ± 0.05 min. Several $\gamma$ rays of ${}_{}{}^{169}{}_{}{}^{}\mathrm{Hf}$ were determined, and a partial decay scheme of ${}_{}{}^{169}{}_{}{}^{}\mathrm{Hf}$ proposed. The previously reported 1.5 h ${}_{}{}^{169}{}_{}{}^{}\mathrm{Hf}$ was found to be in error. The half-lives of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Hf}$, ${}_{}{}^{170}{}_{}{}^{}\mathrm{Hf}$, and ${}_{}{}^{171}{}_{}{}^{}\mathrm{Hf}$ were redetermined to be 25.95 ± 0.20 min, 15.92 ± 0.15 h, and 12.09 ± 0.35 h, respectively. Several new $\gamma$ rays of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Hf}$ were observed. $\gamma$ spectra of ${}_{}{}^{170}{}_{}{}^{}\mathrm{Hf}$ and ${}_{}{}^{171}{}_{}{}^{}\mathrm{Hf}$ were redetermined, and comparisons were made with previous investigations.

• Received 27 March 1970

DOI:https://doi.org/10.1103/PhysRevC.2.310