Evaluation of excited nl-state distributions of fast exit ions after penetrating through solid foils. Part 1: Charge-state fractions for 4.3 MeV/u projectiles with atomic numbers Z = 6–26 passing through carbon foils

Abstract

New experimental data on charge-state evolution fractions Fq(D) and equilibrium charge fractions Fq∞ are presented when 4.3MeV/u projectile ions with an atomic number Z=6–26 passed through carbon foils with thickness of D=10–350μg/cm2. These data are compared with the data at 6.0MeV/u previously reported, and the difference is explained in terms of the energy dependence of the charge-changing cross sections in solid carbon. Using the equations relating the equilibrium fractions Fq∞ with the collision cross sections describing interaction of projectiles with the target atoms, the nl state distributions of exit ions are predicted where n and l are the principal and orbital quantum numbers, respectively. A fitting procedure of getting information about these distributions is described. The influence and importance of the so-called target-density (gas–solid) effects on the collision cross sections for solid targets are also discussed. Using the fitting procedure described in this paper (Part 1), one can obtain information on nl state distributions, which survived after collisions of the projectiles with the target atoms.In the coming second part (Part 2) of our two reports, it will be shown how to estimate the absolute number of exit ions in these nl states.