EISEVIER Nuclear Instruments and Methods in Physics Research A 400 (1997) 476-483 zyxwvutsrqponmlkjihgfedcbaZYXW NUCLEAR INSTRUMENTS &METNoDs IN zyxwvutsrqponmlkjihg PHYSICS RESEARCH Sectlon zyxwvutsrqponmlkji A Test of a high-heat-load double-crystal diamond monochromator at the Advanced Photon Source P.B. Fernandez*, T. Graber, W.-K. Lee, D.M. Mills, C.S. Rogers, L. Assoufid zyxwvutsrqponmlkj Advanced Photon Source, Experimental Facilities Division, Argonne National Laboratory, Argonne, IL 60439. USA Received 20 February 1997 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM Abstract We have tested the first diamond double-crystal monochromator at the Advanced Photon Source (APS). The monochromator consisted of two synthetic type lb (1 1 1) diamond plates in symmetric Bragg geometry. The single- crystal plates were 6 mm x 5 mm x 0.25 mm and 6 mm x 5 mm x 0.37 mm and showed a combination of mosaic spread/strain of the order of 2-4 arcsec over a central 1.4 mm-wide strip. The monochromator first crystal was indirectly cooled by edge contact with a water-cooled copper holder. We studied the performance of the monochromator under the high-power X-ray beam delivered by the APS undulator A. By changing the undulator gap, we varied the power incident on the first crystal and found no indication of thermal distortions or strains even at the highest incident power (200 W) and power density (108 W/mm’ in normal incidence). The calculated maximum power and power density absorbed by the first crystal were 14.5 W and 2.4 W/mm’, respectively. We also compared the maximum intensity delivered by this monochromator and by a silicon (1 1 1) cryogenically cooled monochromator. For energies in the range 6-10 keV, the flux through the diamond monochromator was about a factor of two less than through the silicon monochromator, in good agreement with calculations. We conclude that water-cooled diamond monochromators can handle the high-power beams from the undulator beamlines at the APS. As single-crystal diamond plates of larger size and better quality become available, the use of diamond monochromators will become a very attractive option. zyxwvutsrqponmlkjihgfedcb PACS: 07.85.Qe Keywords: High-heat-flux X-ray optics; Diamond monochromator, Synchrotron radiation 1. Introduction Third-generation synchrotron sources produce X-ray beams of very high power and brilliance. For example, the X-ray beams delivered by the undu- *Corresponding author. Tel.: + 1630 252 2901; fax: + 1 630252 9303: e-mail: fernandez@aps.anl.gov. lators at the Advanced Photon Source can have a total power of several kilowatts, with a peak power density of 160 W/mm2 at 30 m from the source. To take full advantage of the intense beams, the first optical components of an X-ray beamline have to be designed to work under these extreme power loads. In the case of the first crystal in a monochromator, several approaches have been developed: the use of crystals with internal cooling 016%9002/97/$17.00 ,(; 1997 Elsevier Science B.V. All rights reserved PII SOl68-9002(97)01014-O