Antiparticle excitation of atomic inner shells

Antiparticles are shown to produce inner-shell vacancies in atoms with cross sections that can be orders of magnitude larger than those for particles at the same incident velocity. This phenomenon occurs for projectile velocities which are low compared with the orbital velocity of the electrons. The disparity in vacancy production manifests itself through differences in the characteristic x-ray yields induced by particles and antiparticles. The principle of a self-calibrating detector for antiparticle-induced x-ray emission is given.