GEOMETRICAL EFFECT OF TARGET CRYSTAL ON PXR GENERATION AS A COHERENT X-RAY SOURCE

The experiments of the PXR performance carried out for the target crystals with different cutting planes have shown significant difference in the PXR property, which suggests another way to increase the PXR intensity than by increasing the electron beam current. In order to investigate the effect of the geometrical condition of the crystal surface on the PXR property, the experiments have been carried out for the target crystal with a knife-edge-shaped cut surface. For the case with symmetric Bragg geometry on the front surface and asymmetric condition on the rear surface, the rather low intensity X-ray beam has shown considerably good spatial coherence. The X-ray beam with narrow line width has made it possible to obtain X-ray absorption spectra with a high resolution. In contrast, relatively high intensity, which enabled taking an absorption image with the exposure for several tens of seconds, has been obtained for the geometry with asymmetric front surface and symmetric rear surface. This configuration, however, has raised a problem of degradation in the spatial coherence of the X-rays due to the superposition of two different X-ray beams.