Precision Measurement of Delbruck Scattering via Laser Compton Scattered γ-rays

Precision measurements such as the muon anomalous magnetic moment have indicated deviations from the standard model and have in turn prompted higher precision theoretical calculations. Delbruck scattering is the scattering of photons off the Coulomb field of nuclei via virtual electron-positron pairs and has been measured using gamma-rays from radioactivities and following neutron capture reactions. However, because low flux gamma-rays from nuclear transitions have been used in the low photon energy regime fairly large uncertainty exists in the data. In addition, due to the complexity and time consuming nature of the theoretical calculation the scattering cross sections are obtained from tables with interpolation between the tabular values. In recent years high flux.-ray sources via laser Compton scattering (LCS) using energy-recovery linacs have been proposed. These sources allow measuring the Delbruck scattering with high precision. We will present our own independent calculations for the scattering cross section and show what precision can be obtained using the new LCS gamma-ray sources in the low photon energy regime.