0-DEGREES BINARY ENCOUNTER ELECTRON PRODUCTION IN 30-MEV O-Q-2, HE, O-2, NE, AND AR COLLISIONS(+H)

Double-differential cross sections (DDCS's) for the production of bina ry encounter electrons (BEE's) were measured for collisions of 30-MeV O-q+ projectiles with H-2, He, O-2, Ne, and Ar targets with q=4-8 and an electron ejection angle of theta=0 degrees with respect to the beam direction. Particular interest focused on (a) the evaluation of the c ontributions of the different electron subshells of the multielectron targets, O-2, Ne, and Ar; (b) the study of the well-known enhancement of the BEE DDCS's with decreasing projectile charge-state q; here this dependence was tested for higher collision energies and new targets; (c) the study of the dependence of the BEE peak energy on the particul ar target and projectile charge state. Results were analyzed in terms of the impulse approximation, in which target electrons in the project ile frame undergo 180 degrees elastic scattering in the field of the p rojectile ion. The electron scattering calculations were performed in a partial-wave treatment using the Hartree-Fock model. Good agreement with the data was found for the H-2 and He targets, while for the mult ielectron targets O-2, Ne, and Ar only electrons whose velocity was lo wer than the projectile velocity needed to be included for good agreem ent. All measured BEE DDCS's were found to increase with decreasing pr ojectile charge state, in agreement with other recent BEE results. The BEE peak energies were found to be independent of the projectile char ge state for all targets utilized.