Excitation-energy dependence of the giant dipole resonance width

Abstract

High-energy \ensuremath{\gamma} rays have been measured in coincidence with heavy fragents in deeply inelastic reactions of $^{136}\mathrm{Xe}$${+}^{48}$Ti at 18.5 MeV/nucleon. The giant dipole resonance (GDR) strength function is deduced from an analysis of the photon spectra within the statistical model. The GDR width \ensuremath{\Gamma} is studied as a function of the fragment excitation energy ${\mathit{E}}^{\mathrm{*}}$. A saturation at about \ensuremath{\Gamma}=10 MeV is observed for ${\mathit{E}}^{\mathrm{*}}$/A\ensuremath{\ge}1.0 MeV/nucleon.