Giant dipole resonance and Coulomb correction effect in Delbrück scattering studied by elastic and Raman scattering of 8.5 to 11.4 MeV photons

Elastic and Raman scattering of 8.5 to 11.4 MeV $\gamma$-ray photons are investigated between charge numbers of 73 and 92. The experimental elastic scattering cross sections show large deviations from calculations based on available giant dipole resonance photoabsorption cross sections and on lowest order Delbrück amplitudes. The elastic differential cross sections measured at $Z=83\mathrm{} \mathrm{and} 90$ confirm the indications of a Coulomb correction effect in Delbrück scattering previously obtained for $Z=92\mathrm{}$ only. By a systematic analysis, quantitative information on the Coulomb correction effect in Delbrück scattering and on scaling factors for the giant dipole resonance photoabsorption cross sections is obtained.