Channeling of Positrons

Axial and planar channeling in thin single-crystalline gold foils has been investigated by wide-angle scattering of monoenergetic positrons. The beam was obtained by accelerating the positrons emitted from a ${\mathrm{Co}}^{58}$ source in a 1-MeV Van de Graaff. The results are in good agreement with corresponding measurements for protons. For the planar case, classical calculations are compared to calculations based on the dynamical theory of diffraction. The results are very similar except for the "wiggles" due to wave interference, which appear in the quantum-mechanical calculation. These, however, are difficult to resolve experimentally.