The study of giant dipole resonance in hot nuclei in the 40Ar + 93Nb reaction at 25 MeV/u

Gamma rays, light charged particles and evaporation residues emitted from hot nuclei formed in the 40Ar + 93Nb reaction at 25 MeV/u have been measured. The initial excitation energies of the hot nuclei can be deduced from the velocity of the incomplete fusion residues by applying a massive transfer model. The integrated γ multiplicity, after Bremsstrahlung subtraction, is constant as a function of excitation. Statistical calculations were performed by using the CASCADE code, and compared with experimental data. The main effects which can lead to the saturation of the GDR γ multiplicity at high excitation energies were discussed. The experimental data can be fitted by assuming a cutoff of γ emission from the resonance above and excitation energy of approximate 250 MeV