Photoabsorption and Compton scattering in ionization of helium at high photon energies

摘要

Production of singly and doubly charged helium ions by impact of keV photons is studied. The ratio R{sub ph} = {sigma}{sub ph}{sup ++}/{sigma}{sub ph}{sup +} for photoabsorption is calculated in the photon-energy range 2--18 keV using correlated initial- and final- state wave functions. Extrapolation towards asymptotic photon energies yields R{sub ph}({omega} {yields} {infinity}) = 1.66% in agreement with previous predictions. Ionization due to Compton scattering, which becomes comparable to photoabsorption above {omega} {approximately} 3 keV, is discussed.