Thermal damping width of the giant dipole resonance in hot nuclei

An approach describing the thermal damping width of the giant dipole resonance (GDR) in hot nuclei is presented. The GDR is generated by the ph excitations within the finite-temperature random-phase approximation (FTRPA), while its damping at finite temperature arises from irreversible coupling of ph configurations to the thermal pp and hh ones beyond the FTRPA. A semimicroscopic unification of the quantal spreading and thermal damping widths is undertaken within the framework of motional damping. The numerical calculations are performed, using a schematic model with equally degenerate equidistant shells for a hot nucleus of mass A=112 carrying no angular momentum. The results show that the total width of the GDR increases strongly as a function of the excitation energy up to E{sup {asterisk}}{approximately}120{endash}130 MeV, where it reaches a saturation value. The limiting temperature for the GDR in very hot nuclei is discussed. {copyright} {ital 1997} {ital The American Physical Society}