Pair Production by 5-GeV Photons in Carbon

Abstract

The production of wide-angle electron pairs by high-energy photons in the field of the carbon atom has recently been studied at the Cambridge Electron Accelerator. An apparent systematic deviation from the predictions of quantum electrodynamics was observed. In this situation we thought it worthwhile to recheck the total cross section for photon absorption at high energies and reanalyze previous experimental results. Theoretical cross sections were also calculated in detail and comparison of the experimental data was made with several atomic screening calculations. We find that within about 2%, which is the present experimental and theoretical uncertainty, there is reasonable agreement between experiment and theory.