Charge-state dependence of energy loss in random solids

We measured the energy loss of 10-, 16-, and 25-MeV oxygen ions in a thin (7.5μg/cm2) carbon foil as a function of input charge state (q=4 endash 8). At this thickness, charge-state equilibrium is nearly attained, but the energy losses accumulated over the ion close-quote s trajectory are a function of its initial charge state. Using a set of pertinent microscopic atomic collision cross sections computed using the classical trajectory Monte Carlo method, we link these parameters to the observed charge-state dependence on energy loss through a classical transport simulation. This simulation also leads to a prediction of charge-state equilibrium fractions. copyright 1998 The American Physical Society