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A proposal for a highly efficient double‐crystal monochromator for thermal neutrons
Author(s) -
Mikula P.,
Kulda J.,
Vrána M.,
Chalupa B.
Publication year - 1984
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889884011274
Subject(s) - monochromator , mosaicity , optics , bent molecular geometry , neutron , crystal (programming language) , materials science , radius , beam (structure) , monocrystalline silicon , neutron temperature , thermal , silicon , physics , optoelectronics , diffraction , x ray crystallography , nuclear physics , wavelength , computer security , computer science , meteorology , composite material , programming language
The optimum parameters and properties of a new type of neutron monochromator based on elastically bent silicon single crystals are theoretically evaluated. The use of a fully asymmetrical geometry permits the achievement of rocking‐curve widths exceeding 20' in the incident beam. The associated effect of the reflected‐beam widening is compensated for by the second crystal in the parallel (1,−1) setting in opposite geometry. Reflectivity calculations indicate that this double‐crystal system might be compared with the best single‐crystal mosaic monochromators. Besides the easy control of the effective mosaicity and the corresponding integrated reflectivity by variation of the bending radius, a further advantage of this system is its simultaneous action as a neutron filter improving the ratio of the thermal neutron signal to the background.