Neutron fan beam reflectometry

The schemes of measurements of neutron reflectivities with a fan (monochromatic or white) beam are considered; estimations of the luminosity increase are made. The position sensitive detector (PSD) plays the role of a multislit mask, the angular resolution being defined by the slit before the sample (or by a small sample itself) and the spatial resolution of PSD. The fan beam is formed either by an “open source” (transport guide window) or by means of a multichannel fan deviator following the transport guide. A polarized fan beam can be formed by means of a fan polarizer. Bandpass limiting choppers can be used for TOF measurements with a fan beam to eliminate background slow neutrons.