Ionic charge dependence of the zero degree binary encounter peak for partially stripped heavy ions

Abstract

We report on the measurements of double differential cross sections, at zero degree, for the production of secondary electrons from the collision of 0.6 MeV amu-1 Cu5+, I7+, Au11+, U13+, Cu19+ I23+ and Au29+ projectiles with H2 and He. The shapes and positions of the observed binary encounter electron peaks are compared with continuum distorted wave-eikonal initial state (CDW-EIS), impulse approximation and classical trajectory Monte Carlo calculations, as well as with predictions from an adiabatic resonant tunnelling model proposed by Fainstein and co-workers (1992). The experimentally observed binary peak positions were essentially determined by the projectile's ionic charge q and were independent of the projectile's nuclear charge Zp. Although the experimental conditions correspond to the strong perturbation regime. i.e. 1.0<or=q/VP<or=5.9 (VP being the projectile velocity), the CDW-EIS approach accounts well for the position and shape of the binary peak.