Recoil-ion-projectile-ion-cusp-electron triple-coincidence measurements for 1-MeV/u bare and one-electron O and C projectiles on Ne.

Abstract

We have measured in coincidence the projectile-ion charge state, the target-recoil-ion charge state, and the energy of a free electron (cusp electron) emerging from the same collision with a velocity close to the beam velocity, for 1-MeV/u bare and one-electron oxygen and carbon projectiles colliding with neon targets. The most probable recoil-ion charge state of recoil ions not associated with cusp electrons is 1. Most cusp electrons accompany a projectile that does not change charge, and the most probable recoil-ion charge state in this case lies between 2 and 3. The recoil-ion charge-state distribution associated with a cusp electron and bound-state capture by the projectile is shifted towards even higher charge states. Cusp-electron production in conjunction with electron loss by the projectile is not associated with such a large shift. The probability of cusp-electron production given the production of a recoil ion increases with increasing recoil-ion charge state for projectiles that do not change charge and for projectiles that capture an electron, and decreases with increasing recoil-ion charge state for projectiles that lose an electron in the collision.