K-SHELL IONIZATION OF ATOMS BY ELECTRON-IMPACT

K-shell ionization cross sections of silver and gold due to electron impact, with electron energies varying from the ionization threshold to 1 GeV, are calculated. Within the framework of the plane wave Born approximation, with corrections for exchange, Coulomb and relativistic effects, longitudinal as well as transverse interactions of the virtual photons with the atoms are taken into account. Good agreement between the theory and the experiments has been obtained over the whole energy range. Simple analytical expressions, valid for all atoms with Z greater than or equal to 6, for the K-shell Bethe parameters in terms of a single atomic property are also given.