Positron and electron-impact multiple-ionization

Abstract

We present positron-impact multiple (single to quintuple) and total ionization cross sections of Ne, Ar, Kr, and Xe, covering an extended energy range from 50 eV to 7 keV. We improve on previous calculations of the ionization thresholds by adding the mean kinetic energy transferred to the target electrons. In this way the thresholds compare rather well with the experimental appearance energies for the different k-fold ionization cross sections. Present results include not only the novel energy threshold at low energies but also the post-collisional contribution at high energies. We performed a quite complete particle–antiparticle comparison by including our positron-impact results, new calculations for electron-impact ionization including the threshold correction, and a detailed compilation of experimental data. Present positron-impact multiple ionization cross sections are the first ones in such an extended energy region.