Penetration of 4.3 and 6.0 MeV/u highly charged, heavy ions through carbon foils

Experimental data on the charge-evolution functions Fq(D), including equilibrium fractions F∞q, are presented when 4.3 MeV/u C2+ and 6.0 MeV/u Mg5+, Ca6+ and Kr13+ ions from the NIRS-HIMAC injector linac passed through carbon foils with the thickness over D=10-350 μg/cm2 range. The revised experimental F∞q values for 6.0 MeV/u C2+, Ne4+, Si5+, Ar8+, Fe9+ and Cu10+ ions previously reported are also given. The charge equilibrium thicknesses DE for bare and H-like ions are evaluated for projectiles lighter than Ca. The Fq(D),F∞q and DE data are compared with the results calculated by the ETACHA code and the statistical model. It was found that the ETACHA code can reproduce quite well the observed Fq(D), F∞q and DE data for projectiles lighter than Si (atomic number Z=14) but the discrepancy becomes serious for heavier ions. The prediction of the statistical model for the equilibrium charge-state fractions F∞q agrees well with the observed experimental data for ions with Z>18, i.e. heavier than argon