Excitation-ionization and double ionization of helium by Compton scattering

Abstract
We investigate the behavior of the cross section for inelastic photon scattering in the limit of high but nonrelativistic photon energies ω→∞ at helium leading to two-electron transitions. Our calculation employs fully correlated wave functions for the helium ground state and different forms for approximate two-electron final states. We determine the ω→∞ limit for the ratio of double to single ionization. We find the high-energy behavior to differ significantly from the one for photoabsorption. Our results confirm our previous estimate [Andersson and Burgdörfer, Phys. Rev. Lett. 71, 50 (1993)] but disagree with recent predictions by Hino et al. [Phys. Rev. Lett. 72, 1620 (1994)].