Equilibrium charge-state distributions of 35—146-MeV Cu ions behind carbon foils

Abstract

Equilibrium charge-state distributions of Cu ions behind carbon foils have been measured in the energy region 35---146 MeV. The equilibration is obtained with about 30- and 50-\ensuremath{\mu}g/${\mathrm{cm}}^{2}$-thick carbon at energies of 65 and 120 MeV, respectively. Almost-constant values of distribution width have been observed in the 35---47-MeV and 96---146-MeV energy regions. The former corresponds to the Cu ions whose outermost electrons are mainly distributed in the $M$ shell, while the latter in the $L$ shell. The asymmetry of the charge distribution has been observed in the boundary charge state between the Cu $L$ and $M$ shells. Such an asymmetric distribution function has been well approximated with the connection of two Gaussian distributions with an equal centroid but with different standard deviations.