Interference effects in the double ionization of helium by charged particles

The interference between different double-ionization mechanisms by collisions of charged particles with helium is studied in the second order of perturbation theory series in terms of the interaction potential of the projectile with the helium electrons and the correlation potential of atomic electrons. It is shown that the contribution to the interference term in the integrated double-ionization cross section of helium comes only from the interference between the process of independent electron removal and the process in which an ejected electron, as a result of the interaction with the projectile electron, scatters on another helium electron, resulting in double ionization. (orig.)