Multiple Bragg Reflections Are Not Always Negligible and Spurious

In our contribution we present some important results of an exhaustive neutron diffraction studies of multiple Bragg reflections (MBR) accompanying an allowed as well as forbidden reflections. The MBR-observations were carried out, namely, in the frame of Bragg diffraction optics experiments on cylindrically bent perfect single crystals. It has been found that depending on the thickness and curvature of the crystal slabs and the diffraction geometry (reflection, transmission) many strong multiple reflections can be excited which also could be used as a source of highly monochromatic and highly collimated beams for further high-resolution neutron scattering or radiography experiments.