Decay of 18.6-minSe81gand 57.3-minSe81m

Abstract

The $\gamma$ rays following the decay of the ${}_{}{}^{81}{}_{}{}^{}\mathrm{Se}$ isomers have been studied using Ge(Li) detectors and coincidence techniques. $\gamma$ rays of 260.2, 492.4, and 767.3 keV were found to follow the $\beta$ decay of ${}_{}{}^{81m}{}_{}{}^{}\mathrm{Se}$ and $\gamma$ rays of 178.3, 275.9, 290.1, 538.2, 552.4, 566.0, 649.8, and 827.3 keV to follow the $\beta$ decay of ${}_{}{}^{81g}{}_{}{}^{}\mathrm{Se}$. Levels were established at 275.9, 536.1, 538.2, 566.0, 649.8, 767.3, and 828.3 keV. No evidence was observed for levels at 815 or 1146 keV nor was definite $\beta$ feeding observed to known levels at 836.4, 1122, and 1203 keV. The $log\mathrm{ft}$ values are discussed and comparisons of the levels made with those of ${}_{}{}^{79}{}_{}{}^{}\mathrm{Br}$ and ${}_{}{}^{83}{}_{}{}^{}\mathrm{Br}$.