Azimuthal angular dependence of recoil-ion and electron emission in 0.5-MeV p + He collisions

Measurements and n-body classical-trajectory Monte Carlo calculations are presented for the dependence of recoil-ion emission on the azimuthal angle between a projectile and a recoil ion. From the measured momenta of the projectile and the recoil ion, the dependence of the electron emission on the azimuthal angle between projectile and electron is deduced. The recoil ions are found to be emitted to the opposite direction of the scattered projectile only for scattering angles larger than 1 mrad, while for smaller scattering angles, the momentum of the emitted electron results in a broad azimuthal angular distribution of the recoil ions. For a scattering angle of 0.55 mrad, the electrons are predominantly emitted opposite to the scattered projectile, yielding a direct proof of a binary encounter between projectile and electron. © 1993 The American Physical Society.