Anomalous q dependence of 00 binary encounter electron production in energetic collisions of Fq+ (q = 3-9) with He and H2 targets

The projectile charge state dependence of binary encounter electron (BEe) production was studied at zero degrees with respect to the beam direction for collisions of 19 and 28.5 MeV F(3-9)+ with H2 and He targets. The measured double differential cross sections for BEe production were found to be increasingly enhanced with decreasing projectile charge state contary to the usual screening behaviour. The relative enhancement of the BEe F8+ yields over the F9+ yields was found to be about 15% increasing to about 50% for F3+ projectiles. Plausible mechanisms are discussed; however, no theoretical explanation of this anomalous enhancement is established. (author)