ENERGY-LOSS OF MEV PROTONS SPECULARLY REFLECTED FROM METAL-SURFACES

A parameter-free model is presented to study the energy loss of fast p rotons specularly reflected from metal surfaces. The contributions to the energy loss from excitation of valence-band electrons and ionizati on of localized target-atom electronic states are calculated separatel y. The former is calculated from the induced surface wake potential us ing linear response theory and the specular-reflection model, while th e latter is calculated in the first Born approximation. The results ob tained are in good agreement with available experimental data. However , the experimental qualitative trend of the energy loss as a function of the angle of incidence is obtained when the valence-band electron m odel is replaced by localized target atom electron states, though with a worse quantitative agreement.