Nuclear Resonance Fluorescence inRe185

Abstract

The resonant scattering of y rays from the 646-, 718-, and 874-keV excited states of Re 185 has been observed with Nal as well as with Ge(Li) detectors. An Os 185 source, moving on the periphery of a fast rotor at speeds of up to 1.3 X10 5 cm/sec, provided the resonant y rays. From the magnitude of the scattering effects, values of gT Q 2 /T= (2.37±0.15)XH)-5 , (4.8±1.0)XK)-5 , and (2.7±0.3)X10-4 eV were obtained for the widths of these levels, respectively. The angular distributions of the resonance radiations were found to be consistent with the previously accepted spin assignments of J to the 646-keV level, f to the 718-keV leve], and J or f to the 874-keV level. A comparison of resonance scattering and Coulomb-excitation cross sections made it possible to eliminate spin J for the 874-keV level. A value 1.18±0.06 was measured for the ratio of the intensities of the 874-and 879-keV y rays emitted in the disintegration of Os 185 . Evidence for the existence of a level in Re 185 at 929±2 keV was obtained, and upper limits of 0.2% of the ground-state transitions were established for the branchings from the 874-and 879-keV levels to the j + first excited state.The energies and angular distributions of proton groups produced in the Cd 113 (d,p) Cd 114 reaction were measured with an over-all resolution of 12 keV. A distorted-wave analysis, employing experimentally determined optical-model parameters, was used to extract values of /" and spectroscopic strengths for states up to 3.8-MeV excitation in Cd 114 . The spectroscopic factors of the low-energy states are compared with those predicted by a microscopic theory of nuclear vibrations. Reasonable agreement is found for the ground and one-quadrupole-phonon states, but not for the two-phonon states.