When an X-ray area detector based on a single crystalline material, for
instance, a state of the art hybrid pixel detector, is illuminated from a point
source by monochromatic radiation, a pattern of lines appears which overlays
the detected image. These lines can be easily found by scattering experiments
with smooth patterns, such as small-angle X-ray scattering. The origin of this
effect is the Bragg reflection in the sensor layer of the detector.
Experimental images are presented over a photon energy range from 3.4 keV to 10
keV, together with a theoretical analysis. The intensity of this pattern is up
to 20%, which can disturb the evaluation of scattering and diffraction
experiments. The patterns can be exploited to check the alignment of the
detector surface with the direct beam, and the alignment of individual detector
modules with each other in the case of modular detectors, as well as for the
energy calibration of the radiation.Comment: submitted to J Appl Crys
