Conspicuous QED Effects in the Positron-Impact Ionization of U(superscript 91+)

The positron-impact ionization of U(superscript 91+) is studied in the two-potential distorted-wave approximation in QED theory. The effects of the transverse-photon interactions between charges as well as vacuum polarization are analyzed. QED effects conspicuously enhance the cross section at all incident energies.