Open AccessCryogenically cooled bent double‐Laue monochromator for high‐energy undulator X‐rays (50–200 keV)
Author(s) -
Shastri S. D.,
Fezzaa K.,
Mashayekhi A.,
Lee W.K.,
Fernandez P. B.,
Lee P. L.
Publication year - 2002
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/s0909049502009986
Subject(s) - undulator , monochromator , beamline , bent molecular geometry , advanced photon source , optics , monochromatic color , x ray optics , photon , physics , photon energy , particle accelerator , beam (structure) , materials science , x ray , wavelength , composite material
A liquid‐nitrogen‐cooled monochromator for high‐energy X‐rays consisting of two bent Si(111) Laue crystals adjusted to sequential Rowland conditions has been in operation for over two years at the SRI‐CAT sector 1 undulator beamline of the Advanced Photon Source (APS). It delivers over ten times more flux than a flat‐crystal monochromator does at high energies, without any increase in energy width (). Cryogenic cooling permits optimal flux, avoiding a sacrifice from the often employed alternative technique of filtration – a technique less effective at sources like the 7 GeV APS, where considerable heat loads can be deposited by high‐energy photons, especially at closed undulator gaps. The fixed‐offset geometry provides a fully tunable in‐line monochromatic beam. In addition to presenting the optics performance, unique crystal design and stable bending mechanism for a cryogenically cooled crystal under high heat load, the bending radii adjustment procedures are described.