Radioactivities ofRu105,Rh105,Br84, andBr83

A lens spectrometer was used to study the disintegrations of ${\mathrm{Ru}}^{105}$ (4.5 hr), ${\mathrm{Rh}}^{105}$ (36.2 hr), ${\mathrm{Br}}^{84}$ (32 min), and ${\mathrm{Br}}^{83}$ (2.4 hr). ${\mathrm{Ru}}^{105}$ emits a simple beta-spectrum with an end-point energy of 1.150±0.006 Mev. This is followed by a 0.726-Mev gamma-ray to a metastable level in ${\mathrm{Rh}}^{105}$. The decay to the ground state of ${\mathrm{Rh}}^{105}$ proceeds with a gamma-ray of about 0.1 Mev, with a half-life of 45 seconds. The ground state of ${\mathrm{Rh}}^{105}$ emits a simple beta-spectrum of 0.570±0.005 Mev. No gamma-ray appears to be associated with this decay. ${\mathrm{Br}}^{84}$ emits a complex beta-spectrum which can be resolved into at least four groups with end points and relative intensities of 4.679 Mev (40 percent), 3.56 Mev (9 percent), 2.53 Mev (16 percent), and 1.72 Mev (35 percent). The 4.679-Mev group, which goes directly to the ground state of ${\mathrm{Kr}}^{84}$, does not have a forbidden spectrum shape. It is suggested that the 32-minute half-life may be associated with an isomeric level above the ground state of ${\mathrm{Br}}^{84}$. The decay of ${\mathrm{Br}}^{83}$ consists of a single beta-ray group with a maximum energy of 0.940±0.010 Mev.