Perfect crystal neutron optics

Abstract

Double crystal diffractometry is used for investigations in the field of neutron optics of perfect and nearly perfect crystals as well as for small-angle neutron scattering. It is demonstrated on the Si (220) reflection, that the structure factor for perfect crystal reflections can be determined with an accuracy of 0.1% by the simple inclination method. In implanted crystal slices the deformation of the crystal lattice near the implanted layer is investigated. Moreover, the change of this deformation field after light irradiation annealing is proved. Small-angle neutron scattering measurements in the momentum transfer range from 1 × 10⁻⁴ nm⁻¹ to 0.5 nm⁻¹ are possible by using a double crystal diffractometer equipped with perfect or elastically bent crystals. Applying an analyser crystal in fully asymmetric geometry the angular dependence of the SANS intensity is transformed in a positional one, which enables us to employ a position-sensitive detector.