The Use of Crystals with an Asymmetric Reflection Geometry to Measure the Parameters of Electron Beams

The prospects of using crystals with asymmetric reflection geometry to determine the transverse size of relativistic electron beams based on the results of measurements of angular distributions of their radiation in a thin crystal for two distances between it and a coordinate detector are discussed. An experimental test of this technique was carried out using an imaging plate as a two-dimensional position-sensitive detector. Measurements were made for the electron energy of 255 MeV and reflection (220) in a silicon crystal with a thickness of 20 microns and a pixel size of 35 × 35 µm². The distances between the crystal and the detector were 0.5 and 1 m. The obtained values of the horizontal and vertical beam sizes ${\sigma }_x=0.32\pm 0.02\text{mm}$ and ${\sigma }_y=1.35\pm 0.02\text{mm}$ are in satisfactory agreement with the measurement results for optical transition radiation. The possibility of characterizing X-ray plates by comparing the measured and calculated PXR angular distributions for several reflecting planes of crystals with an asymmetric reflection geometry and an asymmetry parameter ε less than unity is discussed.