Inner-shell ionization by ultrarelativistic electrons

We have measured $K$-shell ionization cross sections by electron impact for 19 elements with atomic number in the range $Z=13-92\mathrm{}$, $L$- and $M$-shell ionization cross sections for nine and two heavier elements, respectively, in the energy range 70-270 MeV. The results on the $K$-shell ionization were compared with the predictions from the revised Kolbenstvedt theory and the plane-wave Born approximation calculation by Davidović and Moiseiwitsch, and good agreements were obtained. The $L$- and $M$-shell ionization cross sections were also compared with the predictions from the Kolbenstvedt theory using photoeffect cross sections for these shells and good agreements were obtained, although there is some ambiguity in the photoeffect cross section used in the estimation. The $K$-shell ionization cross sections, together with other experimental results, were represented in a good scaled form based on the revised Kolbenstvedt theory.