Contribution of Compton scattering to the double ionization of helium

Abstract

Double ionization of helium by single-photon impact is analyzed for photon energies from 4 to 12 keV. Many-body perturbation theory is applied to obtain the Compton scattering contribution to the total cross section for double ionization. Compton scattering dominates photoionization above 6 keV. Despite the differences between the two processes, the ratio of double to single ionization by Compton scattering appears to approach the asymptotic value given by photoionization calculations. These ratios are in agreement with recent experiments.