The pair-production channel in atomic processes

摘要

Assisted by the creation of electron-positron pairs,new channels for ionization,excitation,and charge transfer open in atomic collisions when the energy is raised to relativistic values.At extreme energies these pair-production channels usually dominate the "traditional" contributions to cross sections that involve only "positive-energy" electrons.An extensive body of theoretical and experimental work has been performed over the last two decades to investigate charge-changing processes catalyzed by pair production in relativistic heavy ion collisions.We review some of these studies.