Small-displacement monochromator for microdiffraction experiments

We describe the design, construction, and performance of the MHATT-CAT micr odiffraction x-ray monochromator. This monochromator is specially engineere d for x-ray microdiffraction experiments with a high brilliance undulator s ource. The monochromator passes a small emittance beam, suitable for focusi ng to submicron size with submilliradian divergence. Over its energy range of 8-22 keV the absolute energy calibration is better than 2 eV and scans o f +/- 1 keV show no measurable hysterisis. The monochromator operates with a simple water-cooled first crystal and shows no measurable warm-up time. H orizontal linear bearings allow the monochromator crystals to be rapidly in serted or removed from the beam. Slits before and after the monochromator w ork to pass broad bandpass or monochromatic x-ray beams at the same vertica l height. The monochromatic beam direction is adjusted so the monochromatic and broad bandpass beams are coaxial. The design and performance of the mo nochromator allows efficient collection of microdiffraction data when coupl ed to a nondispersive Kirkpatrick-Baez focusing mirror pair. (C) 2000 Ameri can Institute of Physics. [S0034-6748(00)01805-0].