Projectile-charge-state dependence of 0 degree binary-encounter electron production in 30-MeV Oq++O2 collisions

Double-differential cross sections (DDCS's) for the production of binary-encounter electrons (BEE's) are reported for 30-MeV Oq++O2 collisions. The BEE DDCS's were measured at θ=0 degree with respect to the beam direction for projectile charge states q=4--8. The measured BEE DDCS's were found to increase with decreasing charge state in agreement with other recent BEE results employing simpler H2 and He targets. Impulse-approximation calculations of BEE production for θ=0 degree--45 degree are also presented, in which it is assumed that target electrons undergo elastic scattering in the screened Coulomb field of the projectile ion. These calculations are shown to be in agreement with our data at θ=0 degree where only 2s and 2p target electrons are considered