Decay of 83-min 139Ba to levels of 139La and the decay of 18-min 141Ba to levels of 141La.

Abstract

The level structures of odd proton $^{139}\mathrm{La}$ and $^{141}\mathrm{La}$ have been studied in \ensuremath{\gamma}-ray singles, Compton-suppressed singles, coincidence, and angular correlation experiments. No evidence was observed to support the existence of any levels in $^{139}\mathrm{La}$ in the gap between the 166-keV ${d}_{5/2}$ level and the 1209-keV ${(1/2)}^{+}$ level, even though data were accumulated long enough to observe indirect feeding of the ${(1/2)}^{+}$ level. Additional spin and parity assignments are suggested for a number of levels in $^{141}\mathrm{La}$ based on angular correlation measurements.