Symmetric double charge exchange in fast collisions of bare nuclei with heliumlike atomic systems

Double charge exchange in fast collisions between completely stripped projectiles and heliumlike atomic systems is investigated by means of the correct first Born approximation. The theory is devised beyond the usual independent-particle model. For the reason of consistency, the usual proper boundary conditions must be reformulated when dealing with atoms or ions containing more than one electron. Consequently an appropriate correction ought to be introduced in the perturbation potential, which conveniently deals with the difficulty related to the unavailability of exact two-electron bound-state wave functions. For the purpose of illustration, numerical computations are performed for electron capture by α particles from helium. Total cross sections are found to be in satisfactory agreement with the available experimental data from 100 to 2000 keV