Comparison of charge-changing cross sections in gaseous and solid targets

Abstract

The density effect for the particular case of fast ( nu >>Z1 nu 0) ions is investigated by comparing charge-changing cross sections for 36 MeV carbon ions measured in gas and solid carbon targets. It is argued that, for this case, Auger events occurring after the solid targets are negligible; the differences between the gas and solid cross sections can therefore be attributed to processes occurring inside the targets. The solid-target electron capture cross section for the bare nucleus is shown to exhibit a 20% decrease below the gas-target equivalent, and the electron loss cross section for the hydrogenic ion a 60% increase. These results are discussed in terms of projectile excited states within the solid.