New expression for the K-shell ionization

Synopsis A new expression for the total K-shell ionization cross section by electron impact based on the rela-tivistic extension of the binary encounter Bethe (RBEB) model, valid from ionization threshold up to relativistic energies, is proposed. The new MRBEB expression is used to calculate the K-shell ionization cross sections by electron impact for the selenium atom. Comparison with all, to our knowledge, available experimental data shows good agreement. The study of several fields, such as radiation science, plasma physics, astrophysics, elemental analysis using X-ray fluorescence, Auger electron spectroscopy, electron energy loss spectroscopy, and electron probe microanalysis, requires a large and continuous amount of K-shell ionization by electron impact cross section values. The complete quantum-mechanical descrip-tion of the ionization by electron impact of multi-electron atoms and ions is a problem with