Semiclassical Faddeev approximation for electron loss in fast heavy-ion collisions

The ionisation of the projectile in collisions with heavy targets is described by means of the Faddeev expansion. The series is cut off after five terms, which means an inclusion of higher-order interactions of the electron with both the target and the projectile in a symmetric way. This approximation is compared with several theories suggested in the literature. Numerical calculations are presented for the energy distribution of electrons emitted in the forward direction in the case of (H, Ne) collisions.