A highly efficient multi-crystal diffractometer for SANS studies

An improved version of a small-angle neutron scattering instrument based on pairs of elastically bent perfect silicon crystals in the nondispersive (1, -1) setting is proposed. Unlike an earlier version [Mikula, Lukás & Eichhorn (1988). J. Appl. Cryst. 21, 33-37], which employed the first and second crystals in the symmetric Bragg and fully asymmetric geometries, respectively, this new instrument employs the first crystal also in the fully asymmetric geometry. A wide diffracted beam from the first crystal may then be split by slits into several parallel beams directed to the corresponding number of crystal analysers. Moreover, the new geometry of the first crystal offers the possibility of using several reflections operating simultaneously at different wavelengths.