Energy Dependence of Binary Encounter Electron Emission in Collisions of Screened Heavy Bi26+ ions with He Gas Targets

Abstract

Double differential emission cross sections d2σ/dEedΩe (DDCS) of electron emission in collisions of highly charged and partially stripped ions with gas targets deviate dramatically from the predictions of simple theories like the First Born and Binary Encounter (BE) Approximation (C Kelbch et al 1992 Z. Phys. D 22 713 and P Richard et al 1990 J. Phys. B 23 L213). In our experiment the electron emission cross sections were investigated in collisions of partially stripped Bismuth ions with Helium gas targets at projectile energies in the range 1.4 ≤ EP ≤ 6.0 MeV/u. DDCS of electron emission have been measured as a function of the electron emission energy Ee and the observation angle ϑe. The data show systematic enhancement of the BE electron emission for all projectile energies. For the lowest projectile energy the predicted diffraction structures in the Binary Encounter peak were observed at angles between 35° and 45°.