A crystal monochromator based on graded SiGe crystals

Abstract A double SiGe crystal monochromator with a Ge concentration gradient of 0.8%/cm along the crystal surface has been tested using the KMC-2 beamline at BESSY. In comparison with conventional Si crystals an enhancement of energy resolution of 3–8 times with simultaneously an increase of spectral flux of 3–6 were obtained with a naturally divergent synchrotron beam. Effective X-ray beam collimation was experimentally observed by using a graded crystal with optimally bent crystal lattice.