title: DISTORTED WAVE CALCULATIONS FOR ELECTRON IMPACT IONIZATION
       OF Si$^{4+}$ AND Si$^{5+}$

author: Huaguo Teng

affiliation: Institut f\"ur Kernphysik, Justus-Liebig-Universit\"at Giessen,
              D-35392 Giessen, Germany
summary:
Cross sections for electron-impact ionization of Si$^{4+}$ and Si$^{5+}$
ions have been calculated in the distorted wave approximation.
In the present calculations both direct ionization
and excitation-autoionization
processes are included. 
The present results are in resonable agreement with the experimental
measurements of Thompson and Gregory (Phys. Rev. A{\bf 50}, 1377(1994)). 
Remaining discrepancies between the experiment and theory are discussed.