Non-linear calculation of antiproton stopping powers at finite velocities using the extended Friedel sum rule

We calculate the energy loss of antiprotons in an electron gas for non-relativistic velocities by numerical integrations of the radial Schrodinger equation and using an extension of the Friedel sum rule to finite velocities. The calculations cover a wide range of velocities and electron-gas densities, including the range of interest for solid targets. The non-linear calculations are compared with the results of linear theory obtained from the dielectric formulation. A convergence between both calculations is obtained for high velocities and high electron-gas densities. The results show the importance of non-linear effects in the interaction of antiprotons with solids, in particular for energies below and around the stopping power maximum. Tabulated results are presented for a wide range of antiproton energies (5 keV to 3 MeV) and electron-gas densities (r(s) values from 0.2 to 4). These results are applied to calculate antiproton stopping powers of various solids, obtaining good agreement with experiments. (C) 2002 Elsevier Science B.V. All rights reserved.