Spins of the 2350, 2516, and 2547 keV levels inCe140determined fromγ−γdirectional and polarization-directional correlations

Abstract

Directional correlations and polarization-directional correlations have been measured for different $\ensuremath{\gamma}$ 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 ${5}^{\ensuremath{-}}$, ${4}^{+}$, and ${1}^{+}$ for the 2350, 2516, and 2547 keV levels, respectively. The determined mixing ratios are: $\ensuremath{\delta}(131)=\ensuremath{-}0.33\ifmmode\pm\else\textpm\fi{}0.04$, $\ensuremath{\delta}(267)=0.39\ifmmode\pm\else\textpm\fi{}0.05$, $\ensuremath{\delta}(432)=\ensuremath{-}0.54\ifmmode\pm\else\textpm\fi{}0.10$, $\ensuremath{\delta}(868)=\ensuremath{-}0.034\ifmmode\pm\else\textpm\fi{}0.007$, and $\ensuremath{\delta}=0.10\ifmmode\pm\else\textpm\fi{}0.03$.RADIOACTIVITY $^{140}\mathrm{La}$; measured $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}(\ensuremath{\theta})$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}(90\ifmmode^\circ\else\textdegree\fi{}\mathrm{LP})$ (linear polarization correlation) $^{140}\mathrm{Ce}$ deduced $J$, $\ensuremath{\pi}$, $\ensuremath{\delta}$. Ge(Li) detectors.