The effect of projectile wave packet width on the fully differential ionization cross-sections

In this paper, fully differential cross-sections for the ionization of helium by fast charged projectiles (100 MeV/u C⁶⁺ and 3 MeV protons) are calculated. The projectile is described as a wave packet, and the dependence of the cross-sections on the size of the wave packet (coherence width) is investigated. It is shown that the result depends on the coherence properties of the projectile in agreement with the experimental data for incoherent C⁶⁺ and coherent proton projectiles. The most prominent difference between the coherent and incoherent results may be observed for electrons ejected perpendicular to the momentum transfer. (paper)