Ionization of heliumlike ions with excitation of $nl$ states by high-energy photon scattering

We consider the inelastic high-energy photon scattering on heliumlike ions in the ground state, which results in ionization accompanied by simultaneous excitation of the residual ion. Nonrelativistic perturbation theory is employed as a method. The cross sections of the process for transitions into the $ns$ and $np$ states are deduced in the analytical form. A comparison of our results with those of approximated calculations is given.