Multipole mixtures of gamma-ray transitions depopulating the 1318-keV (2−) and 1518-keV (6+or7−) states inYb174

An $E1+E3\mathrm{}$ ($\le 1.9\% M2\mathrm{}$) multipole mixture has been observed for the 1242-keV ($2^{-}$ → $2^{+}$) transition depopulating the $J^{\pi }$, $K=2^{-},2\mathrm{}$ octupole vibrational level at 1318 keV in ${}_{}{}^{174}{}_{}{}^{}\mathrm{Yb}$ following the decay of ${}_{}{}^{174}{}_{}{}^{}\mathrm{Lu}$ and ${}_{}{}^{174}{}_{}{}^{}\mathrm{Lu}_{}^m{}_{}{}^{}$. The internal-conversion cœfficient for this transition and the $\gamma -\gamma$ directional correlation for the 1242-76.5-keV cascade have been remeasured, and the results yield the unique set of multipole mixing ratios ${\delta }_1\left(\frac{M2\mathrm{}}{E1\mathrm{}}\right)=0.05\mathrm{}\pm 0.09$ and ${\delta }_2\left(\frac{E3\mathrm{}}{E1\mathrm{}}\right)=0.19\mathrm{}\pm 0.08$ which correspond to a multipole admixture of $E1({96.3}_{-2.6\mathrm{}}^{+1.7\mathrm{}}\%)+M2({0.2}_{-0.2\mathrm{}}^{+1.7\mathrm{}}\%)+E3({3.5}_{-2.1\mathrm{}}^{+3.8\mathrm{}}\%)$. The $M2\mathrm{}$ multipolarity of the 1318-keV ($2^{-}$ → $0^{+}$) transition was also verified from the measured internal-conversion coefficient. A multipole admixture of $E3\mathrm{}$ ($<27\% M2\mathrm{}$) for the 1065-keV transition was deduced from available data, and the ratios of reduced transition probabilities for the transitions depopulating the 1318-keV level were calculated and compared with rotational-model predictions. Using the previously measured half-life of the $2^{-}$ level, absolute transition probabilities and hindrance factors were obtained for these transitions, and $B\left(E3\mathrm{}\right)\mathrm{}$ values were compared with theoretical microscopic model calculations. Partial correlation coefficients for the 992-keV transition depopulating the 1518-keV isomeric state were determined using the $\gamma -\gamma$ directional correlation data. Multipole admixtures consistent with the correlation data (and internal conversion data for the $7^{-}$ case) are $E2+(27\mathrm{}\pm 8\%)M1$ for the choice of $6^{+}$ and $E1(68\mathrm{}\pm 7\%)+M2(5\pm 2\%)+E3(27\pm 7\%)$ for the choice of $7^{-}$ for the 1518-keV level. Using the reported half-life for that level, the hindrance factors were obtained for the $K$-forbidden transitions depopulating the level for each choice of spin assignment and these are compared with hindrance factors observed for known $K$-forbidden transitions.