Total cross section for ionization of the K shell by electron bombardment

Abstract

The absolute total cross section for ionization of the K shell by electron bombardment has been measured for 13 elements at bombarding energies of 50 and 100 keV. Measurements were made by bombarding thin film targets with a beam of electrons from an electrostatic accelerator and studying the resulting characteristic x-rays. X-rays were observed with solid state detectors: lithium drifted silicon and high purity germanium. Cross sections were extracted from the data by normalization to the theoretical atomic field bremsstrahlung cross sections as calculated by Pratt and tabulated by Kissel, et al. The results were compared with a variety of previous measurements and several different theories. The results are found to be in poor agreement with all of the existing theories. By proper choice of the Bethe parameters, the Bethe theory can be used as an empirical relation to provide a best fit to the available data.