Temperature dependence of the width of the giant dipole resonance in Sn-120 and Pb-208

The giant-dipole resonance (GDR) in Sn-120 and Pb-208 is studied as a function of excitation energy, angular momentum, and intrinsic width. Theoretical evaluations of the full width at half maximum (FWHM) for the GDR strength function, are compared with recent experimental data and are found to be in overall agreement. Differences observed between Sn-120 and Pb-208,, attributed to strong shell corrections in Pb-208 favoring spherical shapes at low temperatures. At high temperature, the FWHM in Sn-120 exhibits effects due to the evaporation width of the compound nucleus.