It is shown that the Bethe parameter $b_K$ for the K-shell ionization of atoms by electrons is the same for various atoms and is numerically twice the value of $b_K$ for the hydrogen atom. Also, a scaling relationship is shown to exist between the oscillator strengths for the K-shell ionization of different atoms and that for the hydrogen atom. Bethe K-shell-ionization cross sections are in good agreement with the experimental data at high energies.

• Received 5 December 1988

DOI:https://doi.org/10.1103/PhysRevA.39.6591