Fast heavy particles in a correlated fermion system: An estimation for the Barkas effect

A calculation for the charge-sign dependence of the stopping power of solid targets for fast-charged particles is performed. The calculation rests on the Bohm-Pines concept for an interacting electron gas: the external bare charge interacts with independent, screened electrons. By using the kinetic theory for scattering description in such a homogeneous system, and the local plasma density approximation with the Jensen atomic model, an estimation for the Barkas effect in real targets is deduced. Comparisons with experimental data, obtained with protons and antiprotons on random stopping, and with the result based on an adiabatic, dressed-perturbation concept are made.