Random and channeled energy loss in thin germanium and silicon crystals for positive and negative 2-15-GeV/cpions, kaons, and protons

Energy loss of 2-, 6-, and 15-GeV/c positive and negative protons, kaons, and pions transmitted through thin germanium and silicon crystals are measured using the crysta\l{}s as intrinsic detectors. For particles incident in directions far from axial or planar directions the results are in accord with the relativistic Beth\'e-Bloch stopping theory. The density effect plays an important role at these energies. The spectral distribution of energy losses is in good agreement with the Landau distribution. For positive particles aligned with an axis or a plane, the energy loss is considerably reduced compared to random. The measurements agree well with theoretical calculations. Negative particles, well aligned to a crystal axis, show increased energy loss compared to random by as much as \ensuremath{\sim}20%.