MS39-P01 Multiple Bragg reflections of neutrons related to a strong allowed reflection Si(004) in a cylidrically bent perfect crystal Pavol Mikula (Neutron Physics Department of Nuclear Physics Institute ASCR, v.v.i., Řež near Prague, Czech Republic) Jan Šaroun (Neutron Physics Department of Nuclear Physics Institute ASCR, v.v.i., Řež near Prague, Czech Republic) Miroslav Vrána (Neutron Physics Department of Nuclear Physics Institute ASCR, v.v.i., Řež near Prague, Czech Republic) Vyachelav Em (National Research Centre ‘Kurchatov Institute’, Moscow, Russia)email: mikula@ujf.cas.czThe experimental results of particular studies of  multiple Bragg reflection (MBR) effects related to a strong Si(400) reflection in the cylindrically bent perfect crystal at the neutron wavelength of 0.162 nm are presented. It has been found that the MBR effects strongly depend on the diffraction geometry of the Si(004) planes with respect to the cut of Si slabs.  Contrary to a common view that the MBR effects could be considered negligible or represent maximally a few percent of an effect related to a single allowed reflection, it has been found that in the case of a particular diffraction geometry their reflecting power can be comparable even much higher than the primary Si(004) reflection. For searching of the MBR effects, the azimuth–Bragg angle relationship for the 004 primary reflection in the diamond structure as displayed in the attached figure, was used. The horizontal dashed line corresponds to the Si(004) reflection for λ=0.162 nm.References:

Keywords: Neutron diffraction, bent perfect crystal, multiple reflection