Projectile charge-state dependence on final-state momentum distributions for single ionization of helium

Abstract

Single-ionization cross sections and final-state momentum distributions have been calculated for the single-ionization collision reactions H{sup +}, {bar p}, He{sup 2+}, C{sup 4+}, and C{sup 6+} + He at 100 keV/u. The classical trajectory Monte Carlo method has been used with a Wigner distribution to improve both the He electron classical radial and momentum distributions. Final-state ionized electron momenta are projected into a collision plane defined by the initial projectile momentum and the final transverse component of the He{sup +} recoil momentum, with the results displayed differentially in various components of electron and recoil momenta. Positively charged projectile impact shows that the soft electrons drift with the recoil ion, while higher-energy electrons move with the projectile and away from the recoiling target. The electron capture to the continuum cusp is present for hard collisions, with asymmetry in both the collision plane and along the longitudinal momenta. Antiproton impact results in soft electrons drifting backward, away from the recoil ion, with the binary-encounter ring clearly observed. {copyright} {ital 1997} {ital The American Physical Society}