Atomic collisions with relativistic heavy ions. II. Light-ion charge states.

Abstract

The influence of excited states of the projectile on the charge states of relativistic heavy ions with Z<20 in solid targets is investigated. A four-state model for the dynamics of electron capture, ionization, and excitation of heavy ions by target atoms is formulated, and a simpler three-state model is solved analytically which explains gas-solid charge-state differences and metastable-state formation. Numerical calculations are compared with data of Crawford et al. for 140--2100-MeV/amu C, Ne, and Ar ions. The ionization, excitation, and radiative capture cross sections can be calculated accurately in this regime with use of the plane-wave Born approximation and the impulse approximation. Nonradiative capture cross sections are extracted from the data and are compared with theory.