The Range of Heavy Ions in Solid Materials

The range of Xe, Kr, A, Ne, and N ions in Al, Be, B, and C has been investigated for incident ion energy in the region 50-500 kev. A monoenergetic ion beam accelerated in an electrostatic accelerator strike a thick target of the stopping material and the penetration depth of the ions beneath the surface is determined by a momentum analysis of monoenergetic protons elastically scattered from the target and embedded atoms. A linear range-energy behavior is observed tor Xe, Kr, and A ions, but dE/dR increases with ion energy for N and Ne ions. The range-energy expression of Nielsen based upon elastic nuclear collisions predicts a constant dE/dR for Xe and Kr ions which is 20 to 28 per cent above the experimental values. A more recent theory by Lindhard and Scharff which includes electron excitation of the stopping atoms fits the Xe in Be, Kr in Be, and Kr in Al experimental data to within (^(+13_(-7)) per cent but is systematically higher than the Xe in Al values by +35 per cent at 50 kev down to +2 per cent at 500 kev. For A, Ne, and N ions, where the low velocity elastic nuclear collision theory is not applicable, the Lindhard-Scharff predictions are from 0 to +15 per cent above the experimental values