Zhongliang Li

A speckle-based method for the X-ray crystal diffraction wavefront measurement is implemented, and the slope errors of channel-cut crystals with different surface characteristics are measured. The method uses a speckle scanning technique generated by a scattering membrane translated using a piezo motor to infer the deflection of X-rays from the crystals. The method provides a high angular sensitivity of the channel-cut crystal slopes in both the tangential and sagittal directions. The experimental results show that the slope error of different cutting and etching processes ranges from 0.25 to 2.98 μrad. Furthermore, the results of wavefront deformation are brought into the beamline for simulation. This method opens up possibilities for new high-resolution applications for X-ray crystal diffraction wavefront measurement and provides feedback to crystal manufacturers to improve channel-cut fabrication.

Ultrathin Pd/B₄C multilayers are suitable X-ray mirrors working at the photon energy region of 7–20 keV. To further improve the layer structure, Pd/B₄C multilayers with a d-spacing of 2.5 nm were fabricated by magnetron sputtering using the heavy noble gas Kr and compared with the conventional ones fabricated by Ar. Although the Kr-sputtering process can work at a lower pressure, the interface width—especially the interface roughness—is a little larger than that made by Ar. A stronger polycrystallization and a lower content of sputter gas atoms were found in the Kr-made sample, which can be explained by the joint effect from less recoiled particles and lower sputtering pressure. A good reflectance of 68% of the Kr made multilayer was measured at 10 keV, which is only slightly lower than that of the Ar made sample (71%).

In this paper, the X-ray diffraction experiment with multiple crystals configuration and its application in characterizing the emission characteristics of double crystal monochromator (DCM) on BL09 beamline of Shanghai Synchrotron Radiation Facility (SSRF) are reported. It is a non-dispersion configuration when the second crystal of DCM and the crystal analyzer form a (+n, -n) type experimental configuration. The rocking curve of the analyzer crystal can only reflect the operation of the DCM. It is the dispersion configurations when the second crystal of DCM and the crystal analyzer form the (+n, +n), (+n, -m) and (+n, +m) type experimental configuration. The width of the analyzer crystal rocking curve includes not only the intrinsic bandwidth of the DCM and the analyzer crystal, but also the angular divergence of the beamline. In this paper, we use the method of DuMond diagram to explicitly illustrate the characteristics of the output beam of the DCM which can be measured under the above two kinds of experimental configurations, and distinguish the diffraction characteristics of different experimental configurations at the same time. Finally, the angular bandwidth and the relative energy bandwidth of the DCM are 5.40(4) arcsec and1.30(1) x 10(-4) @ 10 keV, respectively, which are obtained by deconvolution of the analyzer crystal in (+1, -1) nondispersive configuration. The angular distribution and the relative energy bandwidth of the synchrotron radiation beams are 26(1) arcsec and 6.3(2) x 10(-4) @ 10 keV, respectively, which are obtained by deconvolution of the analyzer crystal and removal of dispersion broadening in (+1, +1), (+1, -3) and (+1, +3) dispersion configuration. After removing the influence of the DCM, the obtained angular divergence of the light source by 25(1) arcsec @ 10 keV, is consistent with the theoretical value of the bending source. In addition, under a series of different white beam entrance slit widths, we characterize the divergence and bandwidth of the beam emitted from the monochromator by the method of multi-crystals dispersion configuration and the DuMond diagram.