Universal cross sections forK-shell ionization by low-velocity protons: Importance of relativistic and energy-loss effects

Recent data reported by Zander and Andrews for $K$-shell ionization of ${}_{22}{}^{}{}_{}{}^{}\mathrm{Ti}$, ${}_{26}{}^{}{}_{}{}^{}\mathrm{Fe}$, ${}_{28}{}^{}{}_{}{}^{}\mathrm{Ni}$, and ${}_{30}{}^{}{}_{}{}^{}\mathrm{Zn}$ by 60-150-keV protons are reanalyzed in terms of the ECPSSR theory of Brandt and Lapicki. The ECPSSR approach takes into account the energy-loss effect (E) as well as the Coulomb deflection (C), perturbed-stationary state (PSS), and relativistic (R) effects. Agreement between theory and experiment is improved, and the remaining discrepancies are partially attributed to inaccuracies of the wave functions utilized in the calculation of inner-shell ionization cross sections.