Sagittal focusing is a widely used geometry to horizontally focus X-rays in synchrotron beamlines. Usually, two types of
devices are used: toroidal mirrors combined with flat X-ray monochromators or flat mirrors combined with sagittal
focusing monochromators. The former option seems to be better since the stresses caused by the bending of the second
crystal in a double crystal monochromator (DCM) are avoided. In this work we explore the effect of sagittal focusing in
medium to high energy resolution X-ray monochromators. Our studies are based on a theoretical explanation of
experimental data acquired in two different experiments performed at the XRD2 beamline at Laboratorio Nacional de
Luz Sincrotron (LNLS / Brazilian Synchrotron) and X18A at the National Synchrotron Light Source (NSLS / BNL /
USA). The first experiment was carried out with a flat meridional bendable mirror followed by a DCM with the second
crystal being sagitally bent. The second experiment was carried out with a flat Si 111 DCM followed by a toroidal, but
meridional bendable mirror. Both setups are completed by a Si 551 4-bounce monochromator to scan the energy
spectrum around 13.7 keV and 13.9 keV, respectively. The results show that the sagittal curvature induces an energy
structure. Theoretical studies made by analyzing the reflecting angles in the mirror surface joined with the dynamical
theory of X-ray diffraction in the 4-bounce X-ray monochromators confirm these results, which are also explored by the
There is currently interest in low strain HPHT diamond due to its expected application as various types of X-ray optical
elements at Synchrotrons, where the X-ray intensity is becoming progressively too severe for the existing materials. The
diamond crystals need to be synthesised with unprecedented lattice quality. In recent measurements at the ID19
beamline of European Synchrotron Radiation Facility (ESRF), the strain sensitivity of the (quantitative) X-ray plane
wave monochromatic topography was increased to the level of 10<sup>-8</sup> using the double crystal technique with successively
higher order reflections and correspondingly higher energy X-rays. At this level the strain fields of certain defects have
a clearly visible macroscopic extent. In particular, both compressive and tensile strain fields of sparse single
dislocations are well observed, as are long range strain fields due to isolated surface scratches. The surface processing
of diamond for low roughness and good near surface crystal quality is a priority. A study of the progress towards this
goal using the X-ray techniques of reflectivity, Grazing Incidence small angle X-ray Scattering (GISAXS) and Grazing
Incidence X-ray Diffraction (GID) has been undertaken. The ability of diamond X-ray optical elements to process X-ray
beams while preserving the coherence properties of the beam is essential to establish, and measurements of this via the
Talbot effect have been carried out. This contribution will detail some of the latest results and comment on future
Two X-ray phase-contrast imaging techniques are compared in a quantitative way for future mammographic applications: Diffraction Enhanced Imaging (DEI) and Propagation. The first uses an analyzer crystal after the sample acting as an angular filter for X-rays refracted by the sample. The latter simply uses the propagation (Fresnel diffraction) of the monochromatic and partially coherent X-ray beam over large distances.
Experiments to compare both modalities have been performed at the Topography Beamline of the European Synchrotron Radiation Facility. The respective set-ups and experimental parameters are described in detail.
Depending on the object properties, the two techniques present a difference in area contrast and edge visibility. DEI shows an enhancement of area contrast for positions of the crystal corresponding to the tails of its rocking curve (RC) and a similar increase but inverted is also visible at the peak of its RC. At the tails, the contrast is mainly produced by ultra small angle scattering, at the peak, it is due to absorption and scatter rejection by the analyzer. At the flanks, it may disappear when attenuation and scattering effects compensate each other. However, an enhancement of the object edges is clearly noticeable, which mainly corresponds to the refracted part.
Propagation reveals an improvement of the edge visibility with the distance and shows negligible area contrast for non-absorbing, large structures.
The influence of metallic contaminants (Ni, Mo) on the oxygen precipitation process during high temperature (HT) treatment under hydrostatic pressure (HP) was studied. No significant influence of Ni and Mo contaminants on the oxygen precipitation process at 1400 K was observed. Changes of interstitial oxygen concentrations c<SUB>0</SUB> after HP-HT treatment for contaminated and for non-contaminated samples were less than 10%. The metallic contaminants (ni, Mo) cause mostly generation of large strain fields in the matrix probably related to metallic precipitates as evidenced by x-ray topography.