Properties of Some Low Excited States inRu101from the Decay of 3-YrRh101

Some properties of low-lying excited states and corresponding transitions in ${}_{}{}^{101}{}_{}{}^{}\mathrm{Ru}$ have been established by studying the decay of ${}_{}{}^{101}{}_{}{}^{}\mathrm{Rh}(T_{\frac{1}{2}}=3.0\mathrm{} \mathrm{yr})$ using scintillation spectroscopy. The three gamma rays associated with this decay with energies in keV (intensities) are 128±3 (89±4), 197±3 (100), 320±10 (24±1). They de-excite levels at 128 and 325 keV. A half-life of 0.55±0.03 nsec was determined for the 128-keV level and a limit of ≤0.3 nsec was set for the 325-keV level using the delayed-coincidence method. The angular correlation between the 128- and 197-keV gamma rays was measured and the results fitted to the formula $W\left(\theta \right)=1+(0.183\mathrm{}\pm 0.025)P_2\left(cos\theta \right)$ or to $W\left(\theta \right)=1+(0.181\mathrm{}\pm 0.025)P_2\left(cos\theta \right)+(0.020\mathrm{}\pm 0.034)P_4\left(cos\theta \right)$. When these results are combined with Coulomb-excitation data, they yield an assignment of ${\frac{3}{2}}^{+}$ for the 128-keV level with a mixing ratio $\delta$ of 0.17±0.05 for the corresponding transition. Although a definitive spin assignment cannot be inferred for the 325-keV level, a spin ${\mathrm{½}}^{+}$ seems the more probable, with $\delta =-\left({{0.15}_{+0.12\mathrm{}}}^{-0.19\mathrm{}}\right)$ for the 197-keV mixed transition.