On experimental realisation of a plane wave of neutrons

We report here numerical computations based on dynamical diffraction theory, leading to the optimised collimator configuration of a silicon {333} Bragg prism for 1.75A neutrons. We propose to attain the first less than 0.07 arcsec collimation of a monochromatic neutron beam by diffracting neutrons from a Bragg prism, viz. a single crystal prism operating in the vicinity of Bragg incidence.