Nuclear Orientation Studies of the Decays ofW187andOs185,191,193

Abstract
Angular distributions have been measured for γ rays emitted following the decays of W187 and Os185,191,193 nuclei polarized at low temperatures in iron. The decay of polarized spin-½ nuclear levels was found to show isotropic angular distributions to three parts in 104, in keeping with angular momentum theory, and purity of the accepted nuclear spin values. The magnitudes of the magnetic moments of the W187 and Os193 ground states have been deduced to be (0.688±0.021)μN and (1.30±0.19)μN, respectively, assuming saturation of the hyperfine field at the nucleus; the magnitude of the magnetic moment of the Ir191 171-keV level has been similarly deduced to be (3.27±0.12)μN, based in part on the observation that the nuclear spin-lattice relaxation time associated with decays from that level is less than 0.1 sec. E2M1 multipole mixing ratios have been deduced for a number of Re187 and Ir193 γ rays, and the multipole characters of several of the β radiations emitted by W187 and Os193 have been obtained; these multipolarities are discussed in terms of the nuclear structure. The use of polarized Os191 as an absolute γ-ray anisotropy thermometer is discussed.