Energy losses of channeled protons

The dependence of the average electron energy losses of protons with E0 = approximately equal to 6 MeV channeled in the brace 110 brace planar channel of a tungsten crystal upon the dechanneling depth has been investigated using the Hartree-Foch approximation for the core electrons and the free electron model of Lindhard for the valence electrons. The calculated results agree qualitatively with the experimental data available. It has been shown that the approximation of the average excitation energies of atomic electrons is not enough to reach a quantitative agreement with experiment and that one should correctly take into account the core-electron excitations caused by the transmitted particles, including those moving near the centre of a channel. It has also been demonstrated that the experimental dependence of the average channeled particle energy losses on the dechanneling depth offers additional possibilities for checking and refining the existing theoretical models of charged particle stopping in solids. (author)