Study of K-shell Ionization Cross-sections of Atoms by Electron Impact

In this paper, we give a description of recent progress on the measurements of electron-impact K-shell ionization cross-sections of atoms in the keV energy range. We present our experimental method of using thin targets with thick substrates and our measurements taken recently to improve the accuracy of the experimental data by an example of measuring K-shell ionization cross-section for Cr element within the incident energy of less than 26 keV. We also compare the K-shell experimental data sets available for 8 low-Z elements and 16 medium- and higher-Z elements in the keV energy range with some theoretical models and empirical formulae. The general comments on the status of measurement and comparison with theories for atomic K-shell ionization cross-section by electron impact are given.