The cross sections for ionization of the excited states of atomic hydrogen by high energy electrons

At large incident electron energies E the cross sections for ionization of the excited states of hydrogen may be written as A (log E )/ E . We use the Bethe approximation to calculate the A 's for all of the degenerate levels of the first five states of hydrogen. The calculations suggest that for the average ionization cross section of these states the A 's are proportional to the -½ power of the ionization potential of the state.