Study of cross-sections for the K-shell ionization of atoms by electron and positron impact

Abstract

In this paper, the K-shell ionization cross-sections of some atoms by electron impact in the energy region less than several ten keV recently measured by our group and by other groups have been compared with the theoretical results of plane-wave Born approximation (PWBA) with Coulomb, relativistic, and exchange corrections as well as the Luo and Joy's theory. These experimental data have also been compared with Casnati et al.'s empirical formula and Deutsch-Margreiter-Märk (DMM) semi-empirical formula, which is modified by us based upon the most recently precisely measured K-shell ionization cross-sections of Cr, Ni, Cu elements of Llovet et al. Moreover, the experimental K-shell ionization cross-section ratios of electron and positron impact have been re-analyzed using the PWBA with Coulomb, relativistic, and exchange corrections. It is found that for most of the elements analyzed in this paper the experimental data are in good or acceptable agreement with the PWBA theoretical results and Luo and Joy's theory and that our modified DMM semi-empirical formula can also provide a good or better description to the experimental data of K-shell ionization cross-section by electron impact.