Radioisotopes of Bromine

Abstract

Selenium metal enriched with ${\mathrm{Se}}^{76}$ was bombarded with 7.3-Mev protons. A new 17.2-hour activity in bromine was observed and is assigned to ${\mathrm{Br}}^{76}$. The radiations of ${\mathrm{Br}}^{83}$, ${\mathrm{Br}}^{80}$, ${\mathrm{Br}}^{77}$, ${\mathrm{Br}}^{76}$, and ${\mathrm{Br}}^{75}$ have been examined by use of a 180\ifmmode^\circ\else\textdegree\fi{} focusing spectrometer and coincidence methods. ${\mathrm{Br}}^{83}$ emits a simple negatron spectrum with a maximum energy of 0.94\ifmmode\pm\else\textpm\fi{}0.02 Mev. The ground state of ${\mathrm{Br}}^{80}$ emits a complex negatron spectrum with components: 1.97\ifmmode\pm\else\textpm\fi{}0.03 Mev (80 percent), 1.1 Mev (11 percent), 0.7 Mev (9 percent). The gamma-rays of ${\mathrm{Br}}^{77}$ are associated with the $K$-capture process. The ground state of ${\mathrm{Br}}^{76}$ emits positrons having a complex spectrum with components 3.57\ifmmode\pm\else\textpm\fi{}0.07 Mev (46 percent), 1.7 Mev (10 percent), 1.1 Mev (11 percent), 0.8 Mev (14 percent), 0.6 Mev (19 percent). Gamma-rays identified with ${\mathrm{Br}}^{76}$ have energies of 0.25, 0.33, 0.37, 0.42, 0.68, 0.75, 0.96, and 1.2 Mev. The ground state of ${\mathrm{Br}}^{75}$ decays by emission of positrons having a complex spectrum with components 1.70\ifmmode\pm\else\textpm\fi{}0.02 Mev (46 percent), 0.8 Mev (20 percent), 0.6 Mev (15 percent), 0.3 Mev (19 percent).