Search

International audience; We report on indirect X-ray detector systems for various full-field, ultra high-speed X-ray imaging methodologies, such as X-ray phase-contrast radiography, diffraction topography, grating interferometry and speckle-based imaging performed at the hard X-ray imaging beamline ID19 of the European Synchrotron—ESRF. Our work highlights the versatility of indirect X-ray detectors to multiple goals such as single synchrotron pulse isolation, multiple-frame recording up to millions frames per second, high efficiency, and high spatial resolution. Besides the technical advancements, potential applications are briefly introduced and discussed.

Nuclear instruments & methods in physics research / A 833, 68 - 76(2016). doi:10.1016/j.nima.2016.07.005, The white beam (∼6–80 keV) available at the TopoTomo X-ray beamline of the ANKA synchrotron facility (KIT, Karlsruhe, Germany) was used to perform edge-enhancement imaging tests on lithium fluoride radiation detectors. The diffracted X-ray image of a microscopic boron fibre, consisting of tungsten wire wrapped by boron cladding, was projected onto lithium fluoride thin films placed at several distances, from contact to 1m. X-ray photons cause the local formation of primary and aggregate colour centres in lithium fluoride; these latter, once illuminated under blue light, luminesce forming visible-light patterns—acquired by a confocal laser scanning microscope—that reproduce the intensity of the X-ray diffracted images. The tests demonstrated the excellent performances of lithium fluoride films as radiation detectors at the investigated photon energies. The experimental results are here discussed and compared with those calculated with a model that takes into account all the processes that concern image formation, storing and readout., Published by Elsevier, Amsterdam

A monolithic monochromator (+n, -n, -m, +m) made of a single block of Ge crystal designed for CoK alpha 1 radiation was developed and tested numerically and experimentally by means of X-ray diffraction. The advantage of monolithic devices is their mechanical stability and the alignment of such optics is much easier than with polylithic optics, but the development of these devices is rather demanding. The presented monochromator belongs to a group of coplanar in-line devices, which means that the input beam is parallel with the output beam. For the estimation of the spectral and angular properties of a diffracted beam of this monochromator (such as bandpass width, output divergence and input acceptance) we used a numerical approach which we call spectral-angular function. It takes into account both the vertical and the horizontal divergence of the input radiation and uses two-beam X-ray dynamical theory of diffraction. Experimentally, the monochromator was tested by means of X-ray diffraction (synchrotron radiation testing) and the results from this characterization are presented. The influence of the vertical divergence on the spectral distribution of the diffracted beam is discussed and compared with previously published analytical results. (C) 2007 Elsevier B.V. All rights reserved.

Using asymmetric diffraction in grazing incidence or in grazing emergence it is possible to expand or compress an x-ray beam in one dimension. Combining two asymmetric diffractions with non-coplanar planes of diffraction it is possible to obtain two-dimensional beam expansion or compression. This paper reports on a monolithic two-dimensional x-ray beam compressor consisting of two non-coplanar asymmetrically inclined {311} diffractors prepared in one silicon crystal block and tested at Optics beamline BM05 at ESRF, Grenoble. The design of the x-ray beam compressor, the results of beam tracing image simulation, the experimental arrangement used for testing and the properties of the x-ray microbeams formed are presented. For the beam energy of 9.5 keV 10- and 13-times beam compression in two directions was observed. Using a metal grid in the incident beam more than 400 microbeams smaller than 10 µm and separated by less than 5 µm were obtained in the outgoing beam. A gain of up to 100 times in intensity per unit area was obtained in comparison with the x-ray beam magnifier geometry, demonstrating a real two-dimensional beam compression.

A total beam compression of 5 and 10 corresponding to the asymmetry angles of 9° and 12° is achieved with V‐5 and V‐10 monochromators, respectively, in standard single crystal pure germanium (220) X‐ray beam compressing (V‐shaped) monochromators for CuKα1 radiation. A higher 1D compression of X‐ray beam is possible using larger angles of asymmetry, however it is achieved at the expense of the total intensity, which is decreased due to the refraction effect. To increase the monochromator intensity, several ways are considered both theoretically and experimentally. Linearly graded germanium rich GexSi(1−x) single crystal was used to prepare a V‐21 single crystal monochromator with 15° asymmetry angles (compression factor of 21). Its temperature gradient version is discussed for CuKα1 radiation. X‐ray diffraction measurements on the graded GeSi monochromator showed more than 3‐times higher intensity at the output compared with that of a pure Ge monochromator.

In standard single-crystal V-channel germanium (220) X-ray beam-expanding/compressing monochromators for Cu Kα1radiation, a total beam expansion/compression of 5 and 10 corresponding to the asymmetry angles of 9 and 12° is achieved, respectively. Higher one-dimensional beam expansion/compression is achievable using larger angles of asymmetry at the expense of a decrease in the total intensity. To increase the intensity, a linearly graded Ge-rich GexSi1−xsingle crystal was used to prepare a monochromator with 15° asymmetry angles (total expansion/compression factor of 21) for Cu Kα1radiation. The X-ray diffraction measurements show more than three times higher peak intensity at the output compared with that of a pure Ge monochromator.

The development of high resolution X-ray measurements and imaging in real and reciprocal space is related to the improvement of the optical elements available for use. Crystal diffractive optics still give the highest resolution in reciprocal space and in energy, and progress has also been made in improving resolution in real space. In this chapter a short introduction to the dynamical theory behind crystal diffractors and their coupling is given and modern one- and two-dimensional elements based on symmetric, asymmetric and inclined diffractions are introduced. The design, the modeling of the output parameters and the experimental results are presented for a special 2-bounce V-shaped monochromator, for a monolithic 4-bounce monochromator and for a monolithic 2D beam de/magnifier.

Within the framework of an FP6 project (SCINTAX)1 we developed a new thin film single crystal scintillator for high resolution X-ray imaging based on a layer of modified LSO (Lu2SiO5) grown by liquid phase epitaxy (LPE) on a dedicated substrate. In this work we present the characterisation of the scintillating LSO films in terms of optical and scintillation properties as well as spatial resolution performances. The obtained results are discussed and compared with the performances of the thin scintillating films commonly used in synchrotron-based micro-imaging applications.

The crystallographic properties of a semiconducting CdTe pixelated sensor were investigated at the ANKA synchrotron facility (KIT, Karlsruhe) by means of back reflection white beam topography and high resolution X-ray diffraction. From the results, several orientation contrast features were identified that could be assigned to small angle grain boundaries of 0.01°. Those structures are disseminated in the whole area of the investigated crystal and form a mosaic structure network of tiled and twisted blocks. The topographic mapping of the sensor was correlated with its X-ray response map. The comparison demonstrates the presence of similar features, proving that the structural quality of the sensor material influences the charge carrier transport and consequently the detector performances.