Angular distributions of 37 $\gamma$ rays were observed following the decays of 161-day ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}_{}^m{}_{}{}^{}$ and 6.8-day ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}_{}^g{}_{}{}^{}$ polarized at low temperatures in the ferromagnetic cubic Laves-phase compound ${\mathrm{ZrFe}}_2$. The magnetic moment of the ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}_{}^m{}_{}{}^{}$ was deduced to be $\left|\mu \right|=(2.74\mathrm{}\pm .21){\mu }_N$, in excellent agreement with the value $\mu =+2.59\mathrm{}{\mu }_N$ computed assuming the ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}_{}^m{}_{}{}^{}$ to be the three-quasiparticle state ${\frac{7}{2}}^{+}{\mathrm{}\left[404\right]\mathrm{}}_p,{\frac{9}{2}}^{+}{\mathrm{}\left[624\right]\mathrm{}}_n,{\frac{7}{2}}^{-}{\mathrm{}\left[514\right]\mathrm{}}_n$. The magnetic hyperfine fields of Lu, Ta, Sc, and Co in ${\mathrm{ZrFe}}_2$ were deduced from the corresponding $\gamma$-ray anisotropies. Decays proceeding through the 1.1-sec ${}_{}{}^{177}{}_{}{}^{}\mathrm{Hf}_{}^m{}_{}{}^{}$ were observed to show characteristic relaxation times of $T_1\approx 6.7$ sec. The $\frac{E2\mathrm{}}{M1\mathrm{}}$ mixing ratios of numerous intraband transitions in ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}$ and ${}_{}{}^{177}{}_{}{}^{}\mathrm{Hf}$ were deduced, and the corresponding $\frac{(g_K-g_R)}{Q_0}$ values were computed. Several interband $\frac{M2\mathrm{}}{E1\mathrm{}}$ mixing ratios were deduced and were compared with calculations based on the Nilsson model including first-order Coriolis mixing. The 0-180° asymmetries of several ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}$ transitions were observed in an effort to see if parity mixing effects might be present due to the particularly close-lying opposite parity states of ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}$; no effects were seen to the limit of 2 × ${10}^{-4\mathrm{}}$.

RADIOACTIVITY ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}_{}^m{}_{}{}^{}$, ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}_{}^g{}_{}{}^{}$; measured $\gamma \left(\theta \right)$ from polarized nuclei; deduced magnetic moment $\mu$, hyperfine field $H$ of impurities in ${\mathrm{ZrFe}}_2$, relaxation time, $\gamma$-ray multipole mixing ratios, $\delta \left(\frac{E2\mathrm{}}{M1\mathrm{}}\right)$, $\delta \left(\frac{M2\mathrm{}}{E1\mathrm{}}\right)$, $g_K$, $g_R$, Coriolis mixing; deduced no observable parity violation.

• Received 11 March 1974

DOI:https://doi.org/10.1103/PhysRevC.10.825