Decay of 54-secBr86and 55-secBr87

The decay of ${\mathrm{Br}}^{86}$ and ${\mathrm{Br}}^{87}$, produced by fission of ${\mathrm{U}}^{235}$, has been studied with $\beta$- and $\gamma$-ray scintillation spectrometers in singles and coincidence operation. Rapid chemical techniques taking advantage of the difference in half-lives of the selenium precursors were used to produce samples having different proportions of ${\mathrm{Br}}^{86}$ and ${\mathrm{Br}}^{87}$, and the radiations following the decay of these two isotopes were resolved in this way. A decay scheme is proposed for ${\mathrm{Br}}^{86}$, with $Q_{\beta }=7.5\mathrm{}\pm 0.5$ MeV.