On shell effects of ionic charge states in solids

Abstract Current models describing the ionic charge states in solids have been reconsidered by noticing the shell effect of ionic charge distributions observed behind a solid target. For this purpose, the source of the shell effect has been investigated by performing Monte Carlo calculations. As a result, the shell effect, which originated inside the foil, has been found to be preserved outside the foil, which leads to the argument that the post-foil Auger electron emission plays only a minor role in the explanation of the difference of heavy ion mean charges between solid and gaseous media. It is concluded that the Betz-Grodzins (BG) model representing the density effect of ionic charge states is not adequate for most of the collisions.