IONIZATION OF RARE-GAS TARGETS BY COLLISIONS OF FAST HIGHLY CHARGED PROJECTILES

We have determined the net ionization cross section for total slow-ion or slow-electron charge production in rare-gas targets by passage of a fast projectile both experimentally and theoretically. We have experimentally studied ionization in these targets by C, Fe, Nb, and Pb projectiles with energies ranging from 310 keV/amu to 4.8 MeV/amu and for charge states in the range of +4 to +54. Theoretical calculations employing the classical-trajectory Monte-Carlo method are used to calculate ionization cross sections in the rare gases for projectiles at collision energies of 1 MeV/amu to 5 MeV/amu with charge states +5 to +80. Experiment and theory generally agree within a factor of 2 over this wide range of conditions. For a given rare-gas target, the cross sections for net ionization reduce to a common curve when plotted as cross section divided by charge state versus energy per nucleon divided by charge state