Directional correlations and polarization-directional correlations have been measured for different $\gamma$ cascades in ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$, populated from the decay of ${}_{}{}^{140}{}_{}{}^{}\mathrm{La}$. Combination of Ge(Li) and INa(Tl) detectors were used in both experiments. For the polarization-directional correlation measurement a planar Ge(Li) detector was employed as the linear polarization analyzer. Combination of the results of these measurements gives unique spin assignments of $5^{-}$, $4^{+}$, and $1^{+}$ for the 2350, 2516, and 2547 keV levels, respectively. The determined mixing ratios are: $\delta \mathrm{}\left(131\right)=-0.33\mathrm{}\pm 0.04$, $\delta \mathrm{}\left(267\right)=0.39\mathrm{}\pm 0.05$, $\delta \mathrm{}\left(432\right)=-0.54\mathrm{}\pm 0.10$, $\delta \mathrm{}\left(868\right)=-0.034\mathrm{}\pm 0.007$, and $\delta =0.10\mathrm{}\pm 0.03$.

RADIOACTIVITY ${}_{}{}^{140}{}_{}{}^{}\mathrm{La}$; measured $\gamma -\gamma \left(\theta \right)$ and $\gamma -\gamma \left(90\mathrm{}°\mathrm{LP}\right)$ (linear polarization correlation) ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ deduced $J$, $\pi$, $\delta$. Ge(Li) detectors.

• Received 28 January 1976

DOI:https://doi.org/10.1103/PhysRevC.13.2461