DAMPING OF NUCLEAR COLLECTIVE MOTIONS WITHIN THE METHOD OF PHASE-SPACE MOMENTS OF THE WIGNER DISTRIBUTION FUNCTION

The semiclassical method of the equations of motion for the phase-space moments of the Wigner function is extended to the inclusion of damping mechanisms. The gross structure of the strength function is obtained going beyond the scaling approximation. Two-body correlations are introduced through an extended relaxation-time approximation. A realistic Skyrme-type interaction is used to derive the self-consistent potential. An application is shown to the damping of the giant monopole resonance (GMR) in Pb-208. The calculated spreading widths with a relaxation-time parameter determined microscopically for the ''collisional'' damping are very much below the observed values. On the other side, consistency is found between the description of the widths of monopole, quadrupole and octupole giant resonances with an empirical value of the relaxation-time parameter.