Decay ofRe184Isomers and the Level Scheme inW184

The decay properties of a rhenium activity followed for over five years have led to its assignment to ${\mathrm{Re}}^{184}$ with isomeric states of 33±3 and 169±8 days. An unidentified rhenium species with a half-life ≥21 years is also present in very small abundance. Energies (and intensities) of the gamma rays determined from the single-crystal and coincidence studies are 0.059(146), 0.111(27.3), 0.163(1.8), 0.217(4.4), 0.253(7.0), 0.318(1.7), 0.384(1.2), 0.539(0.9), 0.540(0.8), 0.641(3.3), 0.770(1.5), 0.793(64.6), 0.894(25.2), 0.904(71.7), 0.909(3.1), 0.97(0.8), 1.03(1.1), 1.04(0.05), 1.16(0.5), and 1.28(0.2) MeV. Gamma coincidence spectra were measured by gating on every gamma-ray peak in the single-crystal spectrum. The 163-keV gamma ray and most of the intensity of the peak at 217 keV appear to be associated with levels in ${\mathrm{Re}}^{184}$, where the latter energy represents the isomeric transition from the 169-day state.