Inner-shell ionization of a neon atom by electron impact

Abstract

A model is proposed to study the inner-shell (K- shell) ionization of the inert gas atoms (e.g., Ne, Ar, etc.) by fast electron impact in coplanar geometry in the framework of a distorted wave approximation. An independent particle model is employed with a one-electron orbital for the multielectron target atom. Triple differential cross sections (TDCS) are presented for both symmetric and asymmetric kinematics of neon atom. The most salient feature noted in the TDCS structure is the presence of intense recoil peak that for certain dynamics (particularly when the ejected energy is much lower than the K-shell binding energy) is even larger than the binary peak, an unusual feature for the outer-shell ionization process. Results are compared with the relative measurements [P. Bickert and W. Hink, in 2nd European Conference on $(e,2e)$ Collisions and Related Problems (Kaiserslautern, 1989), edited by H. Ehrhardt] and the theoretical distorted-wave Born approximation results, available only for asymmetric kinematics. The qualitative agreement of the present results with the experiment by Bickert and Hink is quite good, particularly in respect to the binary/recoil intensity ratio, the latter being greater than unity in both cases for the particular dynamics at which the measurements by Bickert and Hink were performed. Additional results are also presented for symmetric as well as some other asymmetric kinematics.