Radioactive Decay ofSe83

The radioactive decay of ${\mathrm{Se}}^{83}$ produced by ${\mathrm{Se}}^{82}(n,\gamma )$ has been investigated experimentally, leading to a proposed level scheme for ${\mathrm{Br}}^{83}$. The half-life of the long-lived decay was determined to be 22.6±0.2 min, and the 70-sec half-life of ${\mathrm{Se}}^{83m}$ was confirmed. For the long-lived decay, the various coincidence studies lead to a proposed decay scheme incorporating 29 $\gamma$ rays and involving excited levels in ${\mathrm{Br}}^{83}$ at 356, 801, 868, 1094, 1355, 1421, 1438, 1814, 2060, 2650, 2697, 2738, and 2777 keV. The 1094-keV level has been found to have $T_{\frac{1}{2}}=4.1\mathrm{}\pm 0.1$ nsec. Although coincidence measurements have not been made in the study of the short-lived isomer, $\beta$-and $\gamma$-ray spectrum measurements lead to the placement of nine $\gamma$ rays in the proposed decay scheme, with excited levels at 356, 1032, 1063, 2022, 2054, and 2147 keV. $\mathrm{Log}\mathrm{ft}$ values, determined from the studies of $\beta$-ray spectra, have been used to limit spin and parity assignments for many of the levels, while lifetime and directional correlation measurements have provided further limitations on the assignments for a few levels.