Parity Mixing and the Nuclear Structure ofW183,184and Nuclear Spin-Lattice Relaxation Following the Decays of OrientedRe183,184g,184m

A small, but nonvanishing, parity impurity has been determined in the 1285-keV $5^{-}$ level of ${}_{}{}^{184}{}_{}{}^{}\mathrm{W}$, based on observation of the forward-backward asymmetry of the strongly hindered 922-keV $E1\mathrm{}\gamma$ ray from low-temperature polarized ${}_{}{}^{184m}{}_{}{}^{}\mathrm{Re}$. This result has been interpreted in terms of admixing by the weak interaction of a nearby opposite-parity level, based on estimates of the appropriate transition probabilities. Observations of the 0°-90° anisotropies of the angular distribution of $\gamma$ rays from oriented ${}_{}{}^{183,184g,184m}{}_{}{}^{}\mathrm{Re}$ have yielded values for a number of ${}_{}{}^{183,184}{}_{}{}^{}\mathrm{W}$ mixing ratios; in particular, $\frac{E3\mathrm{}}{E1\mathrm{}}$ mixing has been observed in the 922- and 538-keV $\gamma$ rays. The ${}_{}{}^{183,184g,184m}{}_{}{}^{}\mathrm{Re}$ magnetic moments and the corresponding spin-lattice relaxation times of Re in Fe have been determined.