An experimental test of a double-crystal monochromator for thermal neutrons based on two bend silicon crystals

Reflecting properties of a double-crystal (DC) monochromator consisting of two elastically bent perfect silicon crystals in the parallel non-dispersive (1, -1) setting were experimentally treated. Using an unconventional fully asymmetric geometry, the effective mosaicity may be significantly enhanced up to the value of about 10^-2 rad. Test experiments were performed on the 111 and 400 reflections for wavelengths of 0.2 nm and 0.157 nm, respectively. The experimental results obtained are found to be in good agreement with the theoretical predictions published in a previous paper [Mikula, Kulda, Vrána & Chalupa (1984). J. Appl. Cryst. 17, 189-195].