Abstract
The author considers the single ionisation of helium by ions in the Born approximation. The target initial and final states are represented by Hartree-Fock-Slater functions. The author calculates the ionisation probability for a given impact parameter as a function of the energy and ejection angle of the electron. A similar work is also carried out as a function of the projectile scattering angle. The author shows that the projectile scattering is determined by both the projectile-electron and projectile-target-nucleus interactions for scattering angles of the order of 1 mrad. For these small angles, there is no simple relation between the variation as a function of impact parameter and scattering angle.
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