M1Admixtures of Transitions inGd156

Abstract

$\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ directional-correlation measurements were carried out with a NaI-Ge(Li) detector system on the transitions in $^{156}\mathrm{Gd}$ whose levels are populated from the decay of $^{156}\mathrm{Eu}$. Directional correlations of the 88.95-keV $\ensuremath{\gamma}$ ray with 11 transitions which directly feed and 4 which involve a skipped transition to the 88.95-keV state were simultaneously measured. A $\ensuremath{\delta}$ value of ${\ensuremath{-}5.9}_{\ensuremath{-}2.8}^{+1.4}$ was measured for the 1040.44-keV, ${2}_{\ensuremath{\beta}}^{+}\ensuremath{\rightarrow}{2}_{g}^{+}$ transition which is thus (${97.2}_{\ensuremath{-}2.1}^{+1.5}$)% $E2$. The 1065.14-keV, ${2}_{\ensuremath{\gamma}}^{+}\ensuremath{\rightarrow}{2}_{g}^{+}$ transition has a $\ensuremath{\delta}=\ensuremath{-}18\ifmmode\pm\else\textpm\fi{}3$ and a (99.7 \ifmmode\pm\else\textpm\fi{} 0.1)% $E2$ component. Three ${1}^{+}\ensuremath{\rightarrow}{2}_{g}^{+}$ transitions of 1877.03, 1937.71, and 2097.70 keV have $E2$ admixtures of (${13.8}_{\ensuremath{-}2.9}^{+3.0}$), (${24.5}_{\ensuremath{-}1.9}^{+2.0}$), and (${59.0}_{\ensuremath{-}9.0}^{+25.2}$)%, respectively, while the 811.77-keV, ${1}^{+}\ensuremath{\rightarrow}{2}_{\ensuremath{\gamma}}^{+}$ transition is (${0.1}_{\ensuremath{-}0.1}^{+0.4}$)% $E2$.