L3-subshell alignment in gold following low-velocity proton and He+impact ionisation

By measuring the angular distribution of the L l /L gamma intensity ratio of gold following proton (E=0.6-1.5 MeV) and He + (E/M=0.2-1.1 MeV amu -1 ) impact ionisation, the A 2 alignment parameter of the L 3 subshell has been determined. In contrast to the monotonic behaviour of A 2 predicted by the PWBA at low projectile velocities, the authors' experimental data for He + impact exhibit a minimum at E/M approximately=0.4 MeV amu -1 which can be explained by the deflection of the projectile in the Coulomb field of the target nucleus.