Impact-Parameter Dependence of K -Shell Coulomb-Ionization Cross Sections

Coincidence measurements are reported between the characteristic K- shell x rays emerging from a target and the protons of energy 0.3-3 MeV, scattered by 5^∘{} from an incident beam, that cause the primary K-shell ionization. Absolute impact-parameter-dependent differential K-shell ionization cross sections are deduced for Al, Ca, Ni, and Ag. In a reduced plot the data follow a common curve that coincides with the semiclassical prediction of Bang and Hansteen.