L-shell ionization in near-central collisions of MeV protons with low-Zatoms

High-resolution K{alpha} x-ray spectra of Ca, Cr, and Fe induced by (0.7{endash}1.5)-MeV protons and of Ti induced by (0.7{endash}4)-MeV protons were measured by a flat crystal spectrometer. From the relative yields of the KL{sup 1} satellites, which are the result of multiple inner-shell ionization, the average L-shell ionization probabilities in near-central collisions were determined. The effects of the rearrangement of the inner-shell holes prior to the K x-ray emission and the changes of the fluorescence yields due to the multiple ionization were taken into account in the evaluation of the ionization probabilities. The direct Coulomb ionization probabilities in the near-central collisions were determined from the relative yields of the KL{sup 1} satellites after subtracting the shake contribution. The values obtained were compared with semiclassical approximation calculations exploiting relativistic hydrogenic and Hartree-Fock wave functions. The importance of a realistic atomic description using Hartree-Fock wave functions was demonstrated. {copyright} {ital 1997} {ital The American Physical Society}