Differential cross sections for single ionisation of He and D₂by fast protons

Abstract

Differential cross sections for single ionisation of He and D2 by protons have been measured at impact energies of 3 and 6 MeV, and proton scattering angles between 0.1 and 1.0 mrad. A clear shoulder has been observed at an angle of 0.55 mrad. This feature in the differential cross sections is attributed to binary encounters between the protons and the quasi-free target electrons. The measured data are in good agreement in shape and magnitude with both a first Born approximation calculation of the ionisation and with a simple calculation of Rutherford scattering from free electrons.