QUANTAL AND THERMAL DAMPINGS OF GIANT DIPOLE RESONANCES IN 90ZR, 120SN, AND 208PB

The damping of the giant dipole resonance (GDR) is studied in 90Zr, 120Sn, and208Pb as a function of temperatureT . The results show that the coupling of GDR to the pp and hh states is responsible for the increase of the GDR width with increasing T up to 3 MeV and its saturation at higher T . The quantal width, caused by the coupling to ph excitations, decreases slowly with increasing T . An overall agreement is found between the theoretical evaluations and the recent experimental data in heavy-ion fusion reactions and inelastic a scattering. At very highT a behavior similar to the transition from zero to ordinary sounds is observed. [S0031-9007(98)06119-5]