Differential cross sections for single and double ionization of helium by protons and antiprotons

Theoretical and experimental cross sections are presented for single and double ionization of He differential in the projectile scattering angle and the transverse energy of the outgoing recoil ion. A dynamical four-body classical trajectory Monte Carlo method that includes radial electron correlation is utilized to calculate total and differential cross sections for 300 and 500 keV protons and antiprotons in impact collisions with He. The azimuthal emission characteristics of electrons, recoil ion and projectile relative to each other are analysed to provide detailed information on the dynamical differences between single and double ionization and between proton and antiproton impact.