Dependence of the Giant Dipole Strength Function on Excitation Energy

Spectra of γ rays associated with deep-inelastic products from the 1150-MeV ¹³⁶Xe + ¹⁸¹Ta reaction have been measured. The yield of 10-20-MeV γ rays initially increases rapidly with the excitation energy of the products and then more slowly for excitation energies in excess of 120 MeV. Statistical-model calculations with ground-state values of the giant dipole strength function fail to reproduce the shape of the measured γ-ray spectra. This suggests a dependence of the giant dipole strength function on excitation energy.