Isotope Dependence in K, L and M Shell Ionization Cross Sections by Proton and Deuteron Bombardments

Abstract

The ionization cross sections of Al-K, Ti-K, Cu-L, Mo-L, Ag-L and W-M shells have been presented for the incident protons and deuterons in the energy range from 90 to 180 keV/amu. The cross sections are derived from the thick target yields of the respective characteristic X-rays. In contrast with the prediction by Born approximation, isotope dependence is clearly found in the ionization of each target atom. The cross section ratios for K and L shells against the projectile energy per nucleon line up systematically according to the shell binding energies of target atoms. The magnitudes of the K shell ionization cross sections are in good agreement with “binding theory” of Brandt et al. . This means that, in the present energy range, the ionization cross sections depend strongly on the Coulomb deflection of the incident particle and the transient additional binding energy of the K shell electron with the incident particle during the collision.