CALCULATION OF GIANT RESONANCE WIDTHS FROM DAMPED SINGLE PARTICLE MOTION

The spreading and escape widths of giant resonances are evaluated by considering damped particle and hole propagation in the nucleus. The magnitude and averaged A-dependence of the isoscalar quadrupole resonance widths are reproduced qualitatively when the nucleon optical potential, fit globally to low-energy scattering, is used to damp nucleon motion. Contributions from hole state widths and from vertex corrections increase and decrease the giant resonance widths, respectively. Qualitative agreement with experimental widths is shown for 16 O , 40 Ca and 208 Pb . Comparison with recent calculations within continuum RPA is made.