An empirical approach to K-shell ionisation cross section by electrons

Abstract

The working out of an empirical expression for the cross section for production of atomic K-shell vacancies by electrons is described. The basis is a critical analysis of the existing experimental data. The ranges for which the function is evaluated are 6<or=Z<or=79 and 1<or=U<or=20 (U being the ratio between the incident electron energy and the binding energy of electrons in the K shell). The possible meanings of the various factors present in the expression are examined by comparison with the asymptotic Bethe expression. The results obtained by the empirical function can also be applied to both Z and U intervals even wider than those first considered.