Equilibrium Charge-State Distributions for Iodine in Gases (1-12 MeV)

Equilibrium charge-state fractions Fᵢ have been measured for iodine beams with energies between 1 and 12 MeV traversing gas targets of H₂, He, O₂, Ar, and Kr. Charge states from 0 to 14 were detected. At each energy, considerable differences in the charge-state distributions were observed in the different gases; both the mean charge ī and the distribution width σ showed strong dependence on the target gas. At energies above 3 MeV the value of ī was greatest in O₂ and least in H₂, and at all energies the value of σ was greatest in O₂ and least in H₂. At 12 MeV, values of ī and σ in O₂ were 6.15 and 2.04, respectively, whereas in H₂ the corresponding values were 4.02 and 1.12.