Energy straggling of protons through thin solid foils

The energy straggling of protons penetrating thin foils is theoretically and experimentally investigated for intermediate and high impact velocities. We calculate separately the contributions due to the interaction of the projectile with valence and core electrons. The energy straggling originated in the valence band is evaluated within the dielectric formalism, using the Mermin-Lindhard dielectric response function. The contribution coming from the core ionization is calculated with the continuum-distorted-wave-eikonal-initial-state (CDW-EIS) approximation. The predictions of the model are compared with recent measurements for Al, Zn, and Au targets. In addition, experimental results of straggling for Si are presented. The transmission method is used to measure the straggling, and experimental data are corrected to consider roughness effects. Theoretical values are in good agreement with the experiments in the whole range of energies considered. At low energies the binary interaction with valence electrons is the dominant mechanism, while the inner-shell contribution becomes the most important one as the energy increases