Nuclear Structure and Parity Mixing in the Decays from OrientedTa182

Abstract

Angular distributions of 26 $\gamma$ rays in ${}_{}{}^{182}{}_{}{}^{}\mathrm{W}$ have been measured following the $\beta$ decay of ${}_{}{}^{182}{}_{}{}^{}\mathrm{Ta}$ oriented at low temperatures in iron. Triple multipole mixing ($E1+M2+E3\mathrm{}$) of the 1189-keV $\gamma$ radiation was inferred by comparison of the present results with those of $\gamma -\gamma$ directional correlations and internal-conversion measurements; values deduced for the mixing ratios of the 1189-keV radiation were $\delta \left(\frac{M2\mathrm{}}{E1\mathrm{}}\right)=+0.49\mathrm{}\pm 0.03$ and $\delta \left(\frac{E3\mathrm{}}{E1\mathrm{}}\right)=-0.64\mathrm{}\pm 0.05$. $\frac{E2\mathrm{}}{M1\mathrm{}}$ multipole mixing ratios deduced for other $\gamma$ transitions were (energies in keV): $\delta \mathrm{}\left(85\right)=+0.30\mathrm{}\pm 0.02$; $\delta \mathrm{}\left(114\right)=+0.31\mathrm{}\pm 0.02$; $\delta \mathrm{}\left(179\right)=+{0.92}_{-0.07\mathrm{}}^{+0.13\mathrm{}}$; $\delta \mathrm{}\left(1002\right)=-\left({8.9}_{-1.8\mathrm{}}^{+2.1\mathrm{}}\right)$; $\delta \mathrm{}\left(1121\right)=+{21}_{-6\mathrm{}}^{+19\mathrm{}}$; $\delta \mathrm{}\left(1157\right)=-\left({7.6}_{-4.8\mathrm{}}^{+\infty }\right)$; $\delta \mathrm{}\left(1231\right)=-\left({60}_{-20\mathrm{}}^{+100\mathrm{}}\right)$. The $\frac{M2\mathrm{}}{E1\mathrm{}}$ mixing ratios deduced were $\delta \mathrm{}\left(222\right)=+0.007\mathrm{}\pm 0.005$; $\delta \mathrm{}\left(1274\right)=+0.42\mathrm{}\pm 0.04$. The $\frac{E3\mathrm{}}{M2\mathrm{}}$ mixing ratio of the 960-keV transition was deduced to be $-3.6\mathrm{}\le \delta \mathrm{}\left(960\right)\mathrm{}\le +0.3\mathrm{}$. The allowed $\beta$ transition populating the 1374-keV level was determined to be (38 ± 23)% Fermi ($L=0\mathrm{}$) and 62 ∓ 23)% Gamow-Teller ($L=1\mathrm{}$). In the first-forbidden $\beta$ transition populating the 1443-keV level, probably all, but at least half, of the $\beta$ transitions carry one unit of...