Influence of the giant dipole resonance in the statistical decay of the compound nucleus160Er

Abstract

Evaporation residue excitation functions and statistical 7-ray spectra have been measured in the heavy ion fusion reaction ~60+144Nd~16~ between EL~b=76 and 105 MeV. In agreement with statistical model calculations, the evolution of the 7-ray spectra as a function of the compound nucleus excitation energy is consistent with the emission of high-energy ~ rays (E~> 10 MeV) in the early stage of the decay process. The description of the evaporation residue distributions by the statistical model is improved if a 7 strength function including a giant dipole resonance built on each excited state and describing the shape of the measured statistical 7-ray spectra is used in the calculations. The present analysis shows, however, that there is a strong correlation between the parameters of the resonance deduced from the fit to the 7-ray spectra and other parameters of the statistical model, in particular the level density parameter.