Lifetime measurements of scissors mode excitations in Dy162,164

The inelastic neutron scattering reaction has been used to populate known 1(+) scissors mode states in the deformed rare-earth nuclei Dy-162 and Dy-164. The electromagnetic decay properties of these states have been examined and the Doppler-shift attenuation method has been used to measure directly the lifetimes of these states. The M1 strengths determined are in general agreement with those measured previously in nuclear resonance fluorescence experiments and support the conclusion that these are collective structures; however, a significant discrepancy is found for three states near 3.1 MeV in Dy-164. Candidates for 2(+) rotational band members have been identified, and a previously suggested gamma-ray branch from a spin-1 state to the gamma vibration in Dy-164 has been observed.