Saturation of the width of the giant dipole resonance at high temperature

Abstract

The \ensuremath{\gamma}-ray spectrum in the giant dipole resonance (GDR) region associated with the reaction $^{40}$Ar${+}^{70}$Ge at 10 MeV/nucleon has been measured in coincidence with residues of the heavy composite systems whose excitation energy was ${E}^{\mathrm{*}}$=230 MeV. From the statistical-model analysis, it is deduced that the GDR strength is consistent with 100% of the energy-weighted sum rule, the energy is 16\ifmmode\pm\else\textpm\fi{}1 MeV while the width is ${13}_{\mathrm{\ensuremath{-}}2}^{+1}$ MeV. This value is not very different from the one measured at ${E}^{\mathrm{*}}$=130 MeV, thus pointing to saturation effects in the damping of the GDR.