CHARGE-STATE DEPENDENCE OF ENERGY-LOSS IN RANDOM SOLIDS

We measured the energy loss of 10-, 16-, and 25-MeV oxygen ions in a t hin (7.5 mu g/cm(2)) carbon foil as a function of input charge state ( q =4-8). At this thickness, charge-state equilibrium is nearly attaine d, but the energy losses accumulated over the ion's trajectory are a f unction of its initial charge state. Using a set of pertinent microsco pic atomic collision-cross sections computed using the classical traje ctory Monte Carlo method, we link these parameters to the observed cha rge-state-dependence on energy loss through a classical transport simu lation. This simulation also leads to a prediction of charge-state equ ilibrium fractions.