Bent perfect Si crystals as neutron reflectors

Abstract

Bent silicon single crystal platelets appear to be very efficient thermal neutron reflectors. Radii of curvature of 75 cm for 0.5 mm thick platelets have been obtained, which enable one to reflect neutrons from a plane parallel beam with Bragg angles ranging in an angular region of 10° and more. Some specific properties of these systems have been considered. Experiments have been performed which show that for 4 Å wavelength neutrons a reflectivity of 50% over a wide angular region is easily obtained. Some applications of the system as a direct energy analyser or a focusing device are discussed. As an energy analyser the system may be applicable in the energy range of 0.1 meV up to 80 meV.