Dynamic charge state distributions of 5 MeV Xe20+ ions penetrating through gaseous argon target

Dynamic distribution of charge state of highly charged Xe-131(20+) (Z = 54) ions penetrating through the different areal density of gaseous argon target are measured, with the energy of 5 MeV (38.2 keV/u). Two individual stages of charge state are observed: pre-equilibrium stage, where the distribution moves toward the lower charge state with increasing the density of target; equilibrium stage, where the average charge state remains constant as 3.5. The experimental average charge states are compared with the theoretical predictions by the semi-empirical formulas and the classical-trajectory Monte Carlo (CTMC) respectively. A strong dependence of the average charge on energy loss of projectiles is observed too.