No signature of the saturation of giant dipole resonance width in medium-mass nuclei

An experimental study on the temperature (T) dependence of giant dipole resonance (GDR) width was performed for the medium mass nucleus Kr-74 in the range of T approximate to 2-2.5 MeV at an average angular momentum of 26 (h) over bar using the O-16 + Ni-58 fusion reaction. The emitted high-energy gamma rays and evaporated neutrons were measured in coincidence with low-energy discrete gamma-ray multiplicities. The GDR parameters, nuclear level density parameter, and nuclear temperature were determined by the statistical model analysis of the high-energy gamma-ray spectra as well as evaporated neutron spectra. The measured GDR width is found to increase monotonically with temperature, in contradiction with the recent observation of the width saturation in Mo-88. Comparisons of the measured data with predictions of the adiabatic thermal shape fluctuation model and its refined version, the critical temperature included fluctuation model, are presented and discussed.