High-energy target excitations in heavy ion inelastic scattering

The high-energy continuum from inelastic scattering of 84 MeV/nucleon ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ by ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ was studied by measuring ${}_{}{}^{17}{}_{}{}^{}\mathrm{ray}$ coincidences. The particle spectra in coincidence with γ rays above ∼1 MeV show structures up to 45-MeV excitation energy that can be explained in terms of the statistical decay of the highly excited target nucleus. The observation in the γ-ray spectrum of the giant dipole resonance built on excited states in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ confirms that the continuum up to ∼60-MeV excitation energy is dominated by the excitation of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ and offers the unique possibility of detailed studies of the giant dipole resonance as a function of excitation energy decoupled from the influence of angular momentum.