Test of annealed Czochralski grown silicon crystals as X-ray diffraction elements with 145 keV sychrotron radiation

The X-ray diffraction properties of annealed Czochralski grown silicon single crystals have been studied on a triple axis diffractometer using 145 keV synchrotron radiation from the 30 keV critical energy wiggler at CHESS. The silicon crystals, containing approximately 20 ppm oxygen atoms, were annealed at 12000C for 8 h in order to create a homogeneous distribution of defects. A 10 mm thick crystal produced a Laue diffraction rocking curve with a 4 arcsec wide plateau at 50% reflectivity, and a full width at half maximum of approximately 8 arcsec. The shape of the rocking curve could be reproduced by calculations based on Darwin's extinction theory, using a mosaic distribution determined from high resolution γ-ray rocking curves measured from the same crystal. The momentum transfer resolution function of the triple axis spectrometer using these deformed crystals as monochromator and analyzer was also measured. It was found to be enlarged by factors of 11 and 18 in the perpendicular and parallel directions, respectively, compared with the resolution using perfect crystals. This enlarged resolution element can be advantageous in diffuse scattering experiments. (orig.)