Thermally bent ideal crystals as monochromators for neutron scattering

The theoretical behaviour of ideal bent single crystals used for the monochromatization of neutrons is deduced. A device, producing a temperature gradient across the single crystal for maintaining the bending, is described. Experimentally a radius of curvature of 500 cm, a reflectivity of 45% for neutrons with a wavelength of 1.37 AA and an effective mosaic angle of 8' was achieved for a CaF2 single crystal with dimensions 5 cm*10 cm*0.5 cm.