Universal behavior of the electron-electron interaction in the simultaneous projectile and target ionization

Abstract

The antiscreening contribution to the simultaneous projectile and target ionization is analyzed for He+ and C3+ projectiles impinging on noble gas targets. The energy dependence of the average number of target active electrons which contribute to the antiscreening is described by means of a simple function, which is "universal" for noble gases but whose parameters are projectile dependent. A method is presented to estimate the number of active electrons for each target subshell in the high-velocity regime.