FORWARD ELECTRON-EMISSION IN C(Q-HE COLLISIONS())

Differential cross sections are presented for 15-degrees and 20-degree s electron emission in 100- and 150-keV/u C(q+)He collisions where the projectile charge states are 0 to 4+. Coincidences between electrons emitted at 20-degrees and projectiles which captured or lost electrons in the collisions were also measured. The coincidence and noncoincide nce data are used to demonstrate how partial screening of the projecti le nuclear charge and direct interactions between projectile and targe t electrons influence the electron emission. In addition, the relative importance of multielectron transitions associated with either electr on capture or electron loss by the projectile is demonstrated. Finally , the data are used to test whether saddle-point ionization is importa nt in these ionizing collisions, as has recently been suggested. The p resent data do not support this suggestion and are in disagreement wit h the measurements which do support it. Furthermore, it is demonstrate d that dressed ion impact data are inappropriate for testing for a sad dle-point ionization mechanism.