ENERGY-LOSS SPECTRUM OF SWIFT IONS IN CHARGE-STATE EQUILIBRIUM

The energy-loss spectrum of ions in the presence of charge exchange is analyzed theoretically for large path lengths. The evaluation is base d upon steepest-descent integration of the generalized Bothe-Landau fo rmula. General approximation formulas for the spectrum are derived wit hout reference to particular collision cross sections, and their regio ns of validity are discussed. The approximations are tested against nu merical curves for 32-MeV He-3 ions in carbon. General asymptotic expr essions for the peak energy loss and half-widths of the spectrum are f ound. The asymptotic expression for the mean-to-peak interval is speci fied and analyzed. In particular, it is shown and illustrated on a mod el system that the sign of the difference between the peak and mean en ergy loss may be opposite to that in the one-state case.