Double Scattering Effects in the Ionization Spectrum Produced by Single Energetic Atomic Collisions

We present experimental evidence of double scattering processes in the ionization of hydrogenic projectiles by single collisions with He targets at intermediate energies. We observe a distinctive shoulder in the electron velocity distribution in the forward direction at a velocity approximately 3 times greater than the velocity of the projectile. We interpret this structure as due to the emission of projectile electrons which have undergone two consecutive binary scattering processes: one with the target in first place, followed by a second one with the projectile nucleus.