Nuclear Decay of Br84 and the Level Scheme in Kr84

The decay properties of fission product ${\mathrm{Br}}^{84}$ have been studied by scintillation methods. Its half-life was found to be 31.80\ifmmode\pm\else\textpm\fi{}0.08 minutes. Gamma-ray spectra showed gamma rays of energy 0.27, 0.35, 0.43, 0.47, 0.52, 0.61, 0.74, 0.81, 0.879\ifmmode\pm\else\textpm\fi{}0.007, 1.01, 1.21, 1.47, 1.57, 1.74, 1.90\ifmmode\pm\else\textpm\fi{}0.02, 2.05, 2.17, 2.47\ifmmode\pm\else\textpm\fi{}0.03, 2.82, 3.03, 3.28, and 3.93\ifmmode\pm\else\textpm\fi{}0.03 Mev. Single-crystal and coincidence spectrometry established beta-ray groups at 4.71, 3.83, 2.80, 1.81, 1.39, and possibly 0.83 Mev. From these data a level scheme in ${\mathrm{Kr}}^{84}$ has been formulated with excited levels at 0.88, 1.90, 2.17, 2.36, 2.62, 2.71, 2.91, 3.35, 3.70, 3.91, and 4.18 Mev. The mass difference between the ground state of ${\mathrm{Br}}^{84}$ and ${\mathrm{Kr}}^{84}$ is represented by the 4.71-Mev beta ray which includes 32% of the beta-ray transitions.