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

Abstract

Evaporation residue excitation functions and statisticalγ-ray spectra have been measured in the heavy ion fusion reaction16O+144Nd →160Er betweenE Lab=76 and 105 MeV. In agreement with statistical model calculations, the evolution of theγ-ray spectra as a function of the compound nucleus excitation energy is consistent with the emission of high-energyγ rays (Eγ>10 MeV) in the early stage of the decay process. The description of the evaporation residue distributions by the statistical model is improved if aγ strength function including a giant dipole resonance built on each excited state and describing the shape of the measured statisticalγ-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 theγ-ray spectra and other parameters of the statistical model, in particular the level density parameter.