The $K$-shell and $L$-subshell internal-conversion coefficients of the retarded transitions in ${}_{}{}^{177}{}_{}{}^{}\mathrm{Hf}$ populated in the decay of the 6.8-day ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}$ have been measured using a high-resolution double-focusing electron spectrometer and a 20-${\mathrm{cm}}^3$ Ge(Li) detector. The $K$ conversion coefficients of the 71.6- and 113-keV transitions have been determined by $\gamma -\gamma$ and $\gamma$-x-ray coincidence measurements using a 1-${\mathrm{cm}}^3$ Ge(Li) detector having a thin window and a scintillation detector. The $\gamma -\gamma$, $\gamma -e^K$, and $e^K-\gamma$ angular correlations of the 208.3-113-keV cascade have been measured using a single gap electron spectrometer, NaI(Tl) $\gamma$-ray spectrometers, and a Ge(Li) detector. The particle parameters for the $K$ conversion electrons of the transitions have been evaluated to be: $b_2^K$ (208.3) = -1.54 ± 0.06 and $b_2^K$ (113) = -0.20 ± 0.02. The 208.3-113-keV $\gamma -\gamma$ angular correlation as measured using a Lu${\mathrm{Cl}}_3$ source in solution gave $W\left(\theta \right)=1-(0.192\mathrm{}\pm 0.007)P_2\left(cos\theta \right)$. The quadrupole admixtures and the penetration parameters of the transitions were evaluated by least-squares analysis of the conversion coefficients and particle parameters. The best solutions are $Q=(3.1\mathrm{}\pm 1.6)\%$, ${\lambda }_1=-19.2\mathrm{}\pm 1.2$, ${\lambda }_2=250\mathrm{}\pm 240$ for the 321.3-keV transition; $Q<\mathrm{}0.2\%$, ${\lambda }_1=-0.8\mathrm{}\pm 0.9$, ${\lambda }_2=0\mathrm{}$ for the 208.3-keV transition; $Q=(0.03\mathrm{}\pm 0.02)\%$, ${\lambda }_1=1.3\mathrm{}\pm 0.8$ for the 71.6-keV transition; $Q=(94.1\mathrm{}\pm 0.7)\%$, $\lambda =5.6\mathrm{}\pm 8.4$ for the 113-keV transition, and $Q=(95\mathrm{}\pm 5)\%$ for the 136.7-keV transition. From these values and the known lifetimes of the levels the $\gamma$-ray matrix elements and the penetration matrix elements have been calculated and compared with theoretical estimates based on Nilsson's model.

[RADIOACTIVITY ${}_{}{}^{177}{}_{}{}^{}\mathrm{Lu}$; measured $I_{\gamma }$, $I_{\mathrm{ce}}$, $\mathrm{x}\gamma$ and $\gamma \gamma$ coin, $\gamma \gamma \left(\theta \right)$, $\mathrm{ce} \gamma \left(\theta \right)$. ${}_{}{}^{177}{}_{}{}^{}\mathrm{Hf}$, deduced ICC, $b_2^K$, $\delta$, penetration parameters. Double focusing and single gap $e$ spectrometers, Ge(Li) detectors. Enriched target.]

• Received 8 June 1973

DOI:https://doi.org/10.1103/PhysRevC.9.336