Nonrelativistic double photoeffect on K-shell electrons

摘要: We investigate the double K-shell ionization of heliumlike ions caused by absorption a single photon with energies being much smaller than rest energy an electron. In near-threshold region, differential and total cross sections process are calculated for light ions, taking into account leading orders $1/Z$ $\ensuremath{\alpha}Z$ expansions. QED perturbation theory respect to parameter exhibits fast convergence in entire nonrelativistic domain moderate nuclear charge numbers $Zg~2.$ Going beyond electric dipole approximation leads forward/backward asymmetry angular distributions ejected electrons incident beam. A comparison theoretical predictions ratio double-to-single photoionization available experimental data number neutral atoms is also presented.