Reflection High Energy Positron Diffraction from a Si(111) Surface

This report details the first observation of reflection high energy positron diffraction. A 20 keV positron beam was irradiated onto a hydrogen-terminated Si(111) surface from the [11̄0] and [112̄] directions. The zeroth Laue zone consisting of a specular and diffraction spots with a shadow edge was clearly observed using a microchannel plate at relatively high glancing angles (θ>3.0^∘). The rocking curve of the specular spot showed the primary Bragg peak and the total reflection of positrons.