Atomic Physics WorkshopAndrei V. Nefiodov, St. Petersburg Nuclear Physics Institute Double photoeffect on innershell electrons We review the recent progress in theoretical study of the double photoeffect on innershell electrons. The results have been obtained for heliumlike ions within the framework of QED perturbation theory, taking into account the leading orders of the $1/Z$ and $\alpha Z$ expansions. In the electric dipole approximation, the universal scalings can be obtained for the differential and total cross sections of the process under consideration. Going beyond the dipole approximation leads to a forward/backward asymmetry in the angular distributions for the ejected electrons with respect to the incident photon beam. We present also a comparison of our theoretical predictions for the ratio of doubletosingle photoionization cross sections with available experimental data for a number of neutral atoms. Finally, we consider the timereversed process of the correlated doubleelectron capture by a bare nucleus with emission of a single photon. Available theoretical results and experimental perspectives are discussed.  

