Focusing and reflectivity properties of a parallel double bent crystal ( plus n,-m) setting

0433182 - ÚJF 2015 RIV GB eng C - Konferenční příspěvek (zahraniční konf.)
Mikula, Pavol - Vrána, Miroslav - Pilch, Jan - Šaroun, Jan - Seong, B. S. - Woo, C. - Em, V.
Focusing and reflectivity properties of a parallel double bent crystal ( plus n,-m) setting.
Journal of Physics Conference Series. Vol. 528. Bristol: IOP Publishing Ltd, 2014 - (Ioffe, A.), 012003. ISSN 1742-6588.
[International Workshop on Neutron Optics and Detectors (NOP&D 2013). Munich (DE), 02.07.2013-05.07.2013]
Grant CEP: GA MŠMT LM2011019; GA ČR GB14-36566G; GA MŠMT LM2010011
GRANT EU: European Commission(XE) 283883 - NMI3-II
Institucionální podpora: RVO:61389005
Klíčová slova: double bent crystal * diffrraction * monochromator
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus

After preliminary results obtained and published recently ill, in our contribution focusing and reflectivity properties of the dispersive double bent-crystal arrangement are presented in much more detail. It has been found that two different bent perfect crystals in (+n,-m) setting can be good candidates for high efficiency neutron microfocusing as well as high-resolution monochromatisation. Due to the (+n,-m) setting of two different bent perfect crystals, a high resolution is expected in both Delta(2 theta) (2 theta is the scattering angle) as well as Delta lambda/lambda (lambda is the neutron wavelength). Experimental tests were carried out with the setting employing the bent Si(111) slab and Si(220)-sandwich, which contained either one, or two or four 1.3 mm thin simply stacked slabs. Thanks to a high reflection probability of both bent elements and an easy manipulation with the curvature of the Si(220)-sandwich, an excellently focused intensive monochromatic beam of the width from one to several millimetres was obtained. The properties of the double bent-crystal setting were studied in Rez at the neutron optics diffractometer for the neutron wavelength of 0.162 nm and for various thicknesses and curvatures of the Si(220)-sandwich. It has been also found that besides an excellent focusing and reflectivity properties of the dispersive double bent-crystal setting the obtained monochromatic neutron current is sufficiently high for standard high-resolution diffraction experiments even at the medium power research reactor.
Trvalý link: http://hdl.handle.net/11104/0237452