K-Shell Cross Sections Extracted from Measured Charge-State Distributions for F and Si Ions Penetrating C

Abstract

Charge-state distributions have been measured as a function of foil thickness and incident projectile charge state for 4.5-9.0 v0. F ions and 6.0-9.0 v0 Si ions transmitted through thin carbon foils. The charge-state distributions are analyzed in terms of separate K- and outer-shell populations. The outer-shell population is demonstrated to depend on the number of K vacancies in the ion. The ionic K-shell population inside the solid is described in a three-component model, and cross sections for creation and quenching of single and double K vacancies were extracted from a fit to the data. Based on these cross sections, different types of interactions involving the ionic K shell inside solid carbon could be identified: electron excitation and ionization, electron capture, and spontaneous decay of outer-shell electrons.