Experimental cross sections for K-shell ionization by electron impact
A comprehensive compilation of experimental K-shell ionization cross sections induced by electron impact has been assembled, including results up to December 2024. The data are organized according to the target atomic number and to the incident electron energy for elements ranging from H to U. From the 2509 reported data, more than 50% pertain only to 8 elements (H, He, Ar, Cr, Fe, Ni, Cu, and Ag). Conversely, 13 elements have only one or two results, and no data is available for 27 elements in the range of atomic numbers considered. Additionally, a further inspection of the database reveals that the majority of the data is concentrated within a small energy range, spanning up to four times the K-shell ionization energy. Finally, the different methods used to measure the ionization cross section are analyzed and a discussion about the main sources of uncertainties is presented.