Three- and four-body dynamics in fast heavy ion?atom ionization

Single ionization of helium by impact of 3.6 MeV u−1 Au53+ ions is investigated by means of quantum-mechanical and classical methods. Calculations of fully differential cross sections are compared with recently published data for ionization of low-energy electrons as a function of the momentum transferred by the projectile to the target system. A description of initial and final states of the He atom in terms of a Hartree–Fock potential provides an improvement over previous hydrogen-like models. The present results show that inclusion of the resolution and uncertainties present in the experiment has a major influence on both the shape and magnitude of the cross sections. The effect of four bodies and electron–electron correlation is also investigated. However, after including the experimental conditions into the calculations, the three- and four-body results present similar behaviour.