ELECTRON-EMISSION IN CHARGED-PARTICLE SOLID INTERACTIONS

"Charge asymmetry effects" have been investigated through measurements of secondary electrons. Antiprotons and negative muons in the energy range of ∼MeV/u have been employed as negative "heavy" projectiles. It is found that electron intensities in the forward direction for antiprotons are an order of magnitude lower than for protons around υe∼ υp, where υe and υpare electron and projectile velocities, respectively ( "anticusp" vs "cusp"). The cusp-shaped peak has been found to be strongly suppressed for electrons accompanying Ho in H-+Cfoil collisions. Angular-momentum distributions of excited states [C2+ (1s22pnl) and S12+(1s22pnl)] of ions have been measured. Enhancements of high-l components have been observed for foil targets as compared with gas targets. A three-step scheme involving ionization, transport and emission is shown to be effective for the understanding of these findings. © 1990.