Delbrück scattering of 1.115 MeV photons

The contribution of Delbrück scattering to the elastic scattering of photons has been investigated for photon energy of 1.115 MeV. Differential cross-sections for the elastic scattering of 1.115 MeV photons, using gamma-ray isotope 65Zn, have been measured from high-Z   target atoms (Z=74Z=74 and 82) at angles ranging from 30° to 135°, using a high-purity co-axial germanium detector and computer-based data acquisition hardware and data analysis software. S-matrix theoretical calculations of Rayleigh scattering cross-sections were performed at 1.115 MeV and the experimental results were compared with these theoretical computations, which include Delbrück and nuclear Thomson amplitudes. The present experimental data at 1.115 MeV indicate that Delbrück amplitudes calculated with lowest-order Born approximation are sufficient, as at 1.33 MeV, when combined with S-matrix-Rayleigh scattering amplitudes.