Binary encounter electron emission in collisions of highly charged ions with helium gas targets

Abstract

The energy and angular distribution of δ-electrons produced in collisions of bare argon projectiles with helium gas targets are reported. Double differential electron emission cross sections, d 2 σ dE e dΩ e , have been measured as a function of the electron emission energy, E e, and the polar electron emission angle, V e. The major interest was directed upon the angular dependence of the integrated single differential emission cross sections of the binary encounter (BE) electrons, dσ(Θ e ) dΩ e . The cross sections are compared with electron argon scattering data (calculated and tabulated in Phys. Rev. A 15 (1977) 2173 [1]) as well as experimental data derived from light ion impact on helium (ionic charge q≤9+). The theoretical results are calculated with the impulse approximation (IA) model developed by Lee et al. (Phys. Rev. A 41 (1990) 4816 [2]). Even for higher ionic charge states the measured BE electron emission cross sections are well described by the IA model and are found to scale quadratically with the ionic charge state, q 2, and the projectile energy, E p 2.