Equilibrium charge states of swift F ions after passage through thin foils: Projectile-velocity dependence and target-atomic-number dependence

Abstract

Equilibrium charge-state distributions of F ions have been measured in the collisions of (1) (29-108)-MeV F+C and (2) 30- and 60-MeV $F+_{{Z}_{2}}X$ foils. Measurement (1) is done to investigate the projectile-velocity dependence of the mean charge state, distribution width, and charge-distribution function. Measurement (2) is done to investigate the ${Z}_{2}$ (target atomic number) dependence of F-ion charge states using 20 kinds of foils with different ${Z}_{2}$. Contrary to the ${Z}_{2}$ oscillation of mean charge states of swift Si and Cl ions, obvious ${Z}_{2}$ oscillatory behavior has not been observed in 30- and 60-MeV F ions. Generally, higher-charge states are observed after passage through lower-${Z}_{2}$ foils, which follows a trend similar to the ${Z}_{2}$ dependence of effective charges estimated from stopping powers.