Projectile charge and velocity dependence of L-subshell ionization cross sections ratios for heavy elements

L-subshell ionization cross-section ratios for heavy elements induced by protons, ..cap alpha..'s, carbon ions, and oxygen ions in the range 0.5 to 6.0 MeV/amu have been investigated. The resulting ratios of sigma/sub L/1/sigma/sub L/2 and sigma/sub L/3/sigma/sub L/2 show large deviations from the plane-wave-Born approximation, semiclassical-approximation, and binary-encounter-approximation predictions below 2 MeV/amu. These deviations are more pronounced for higher projectile charges. (AIP)