Total inelastic energy loss by heavy ions stopped in a gas

Abstract

Calculations are made of the total energy lost to inelastic channels when a fast ion or atom is stopped in a gas. Contributions to this energy loss by sufficiently energetic recoil atoms are included, using a scheme of successive approximations, which reveals the relative importance of successive generations of recoils. The electronic energy losses resulting from a single collision are computed according to the theories of Lindhard and of Firsov, which are modified by the presence of a threshold function. It is shown that such a threshold is essential to calculations employing physically reasonable interaction potentials. Energy losses associated with the nuclear motion are treated as classical elastic scattering, and the sensitivity of the calculations to the assumed potential is demonstrated. The relative accuracy of approximations to the deflection function computed for several potentials is investigated.