Short-Lived Isomers ofTa181

Abstract

Excited states of ${\mathrm{Ta}}^{181}$ which result from the 46-day $\beta$-decay of ${\mathrm{Hf}}^{181}$ were investigated by the method of delayed coincidences. Using trans-stilbene scintillation counters and a coincidence system of about 1.3×${10}^{-8\mathrm{}}$-sec. resolving time, a state with a half-life of (1.08±0.05)×${10}^{-8\mathrm{}}$-sec. was observed. Delayed coincidence absorption experiments indicated that the radiation following the delayed state arises chiefly from a transition of about 0.5-Mev energy.