The time-dependent perturbation theory has been applied to the description of the L-shell ionization of atoms by heavy charged particles in the independent-particle model approximation. A second order correction factor to cross sections calculated in a first order theory (e.g. PWBA) has been derived considering transitions at an average impact parameter and with minimum energy transfer as dominant ionization processes in low-velocity collisions. Numerical calculations have been performed for light and heavy (Z1 ≤ 8) ion impact ionization of gold in the energy range 0.15-2.0 MeV u. The results are in satisfactory agreement with the experimental data for the L3-to-L2 and L1-to-L2 subshell ionization cross section ratios. The model seems to account also for the anomalous behaviour of the L3-subshell alignment observed recently at heavy-ion impact.
ASJC Scopus subject areas
- Nuclear and High Energy Physics