Dependence of the Giant Dipole Strength Function on Excitation Energy

Abstract

Spectra of $\ensuremath{\gamma}$ rays associated with deep-inelastic products from the 1150-MeV $^{136}\mathrm{Xe}$ + $^{181}\mathrm{Ta}$ reaction have been measured. The yield of 10-20-MeV $\ensuremath{\gamma}$ 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 $\ensuremath{\gamma}$-ray spectra. This suggests a dependence of the giant dipole strength function on excitation energy.