Open AccessX‐ray Optics of a Dynamical Sagittal‐Focusing Monochromator on the GILDA Beamline at the ESRF
Author(s) -
Pascarelli S.,
Boscherini F.,
D'Acapito F.,
Hrdy J.,
Meneghini C.,
Mobilio S.
Publication year - 1996
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049596004992
Subject(s) - monochromator , beamline , optics , physics , bent molecular geometry , synchrotron radiation , diffraction , x ray optics , beam (structure) , resolution (logic) , full width at half maximum , materials science , x ray , wavelength , artificial intelligence , computer science , composite material
The performance of a dynamical sagittal‐focusing monochromator for hard X‐rays is described. It consists of a flat first crystal and a diamond‐shaped ribbed second crystal which is clamped by its central rib and dynamically bent by applying a force on its two apices. The system has proved to perform very well on the GILDA beamline at the ESRF. The horizontal acceptance varies with energy and with focusing geometry as predicted theoretically; the total available horizontal fan of radiation (3.6 mrad) is in fact collected in the 1:3 geometry. The system is routinely run in a dynamical focusing mode for XAFS spectroscopy in the energy range 5–30 keV with Si(311) crystals, with a constant spot size FWHM ~1 mm on the sample and without degradation of energy resolution or reproducibility. Using simple geometrical considerations we calculate the variations of the horizontal profile of the reflected beam during rocking‐curve scans in different focusing geometries and find them in agreement with observed ones. Not only is this is a practical aid in alignment but it illustrates the X‐ray optics of sagittal focusing in an elegant way.