A large-area perfect crystal neutron interferometer optimized for coherent beam-deflection experiments: Preparation and performance

Abstract The fabrication and benefits of the actually largest perfect crystal interferometer are presented. New features are longer beam paths, precise symmetric lattice orientation and the use of several higher order reflections. The optimized design offers ample space for beam manipulators, in particular the use of different prism arrangements for coherent beam-deflection experiments. The interferometer can be utilized in one- or two-loop configuration at different wavelengths (2.7, 1.36, 0.9 and 0.7 A) by selecting (2 2 0) or higher order reflections (4 4 0), (6 6 0) and (8 8 0), without changing the beam geometry. The interferometer was tested successfully at ILL instrument S18 where 73% visibility of interference fringes have been reached in (4 4 0) reflection. This indicates that larger interferometers of this type are feasible in future.