A large-solid-angle X-ray Raman scattering spectrometer at ID20 of the European Synchrotron Radiation Facility

An end-station for X-ray Raman scattering spectroscopy at beamline ID20 of the European Synchrotron Radiation Facility is described. This end-station is dedicated to the study of shallow core electronic excitations using non-resonant inelastic X-ray scattering. The spectrometer has 72 spherically bent analyzer crystals arranged in six modular groups of 12 analyzer crystals each for a combined maximum flexibility and large solid angle of detection. Each of the six analyzer modules houses one pixelated area detector allowing for X-ray Raman scattering based imaging and efficient separation of the desired signal from the sample and spurious scattering from the often used complicated sample environments. This new end-station provides an unprecedented instrument for X-ray Raman scattering, which is a spectroscopic tool of great interest for the study of low-energy X-ray absorption spectra in materials under insitu conditions, such as inoperando batteries and fuel cells, insitu catalytic reactions, and extreme pressure and temperature conditions.Peer reviewe

A method for high-energy, low-dose mammography using edge illumination x-ray phase-contrast imaging

Since the breast is one of the most radiosensitive organs, mammography is arguably the area where lowering radiation dose is of the uttermost importance. Phase-based x-ray imaging methods can provide opportunities in this sense, since they do not require x-rays to be stopped in tissue for image contrast to be generated. Therefore, x-ray energy can be considerably increased compared to those usually exploited by conventional mammography. In this article we show how a novel, optimized approach can lead to considerable dose reductions. This was achieved by matching the edge-illumination phase method, which reaches very high angular sensitivity also at high x-ray energies, to an appropriate image processing algorithm and to a virtually noise-free detection technology capable of reaching almost 100% efficiency at the same energies. Importantly, while proof-of-concept was obtained at a synchrotron, the method has potential for a translation to conventional sources

A noiseless kilohertz frame rate imaging detector based on microchannel plates read out with the Medipix2 CMOS pixel chip

A new hybrid optical imaging detector is described that is being developed for the next generation adaptive optics (AO) wavefront sensors (WFS) for ground-based telescopes. The detector consists of a photocathode and proximity focused microchannel plates (MCPs) read out by the Medipix2 CMOS pixel ASIC. Each pixel of the Medipix2 device measures 55x55 um2 and comprises pre-amplifier, a window discriminator and a 14-bit counter. The 256x256 Medipix2 array can be read out noiselessly in 287 us. The readout can be electronically shuttered down to a temporal window of a few us. The Medipix2 is buttable on 3 sides to produce 512x(n*256) pixel devices. Measurements with ultraviolet light yield a spatial resolution of the detector at the Nyquist limit. Sub-pixel resolution can be achieved using centroiding algorithms. For the AO application, very high continuous frame rates of the order of 1 kHz are required for a matrix of 512x512 pixels. The design concepts of a parallel readout board are presented that will allow this fast data throughput. The development status of the optical WFS tube is also explained

A high-energy-resolution resonant inelastic X-ray scattering spectrometer at ID20 of the European Synchrotron Radiation Facility

An end-station for resonant inelastic X-ray scattering and (resonant) X-ray emission spectroscopy at beamline ID20 of ESRF - The European Synchrotron is presented. The spectrometer hosts five crystal analysers in Rowland geometry for large solid angle collection and is mounted on a rotatable arm for scattering in both the horizontal and vertical planes. The spectrometer is optimized for high-energy-resolution applications, including partial fluorescence yield or high-energy-resolution fluorescence detected X-ray absorption spectroscopy and the study of elementary electronic excitations in solids. In addition, it can be used for non-resonant inelastic X-ray scattering measurements of valence electron excitations.An end-station for resonant inelastic X-ray scattering at beamline ID20 of ESRF - The European Synchrotron is described. The spectrometer is optimized for high-energy-resolution applications, including partial fluorescence yield or high-energy-resolution fluorescence detected X-ray absorption spectroscopy and the study of elementary electronic excitations in solids

Characterisation of pixelated CdZnTe sensors using MAXIPIX

International audienceIn order to maximise the absoprtion efficiency of X-ray detectors for high energy photons above 20 keV, compound semiconductor sensors with high atomic number (Z) are under investigation. A promising material for future detector systems is Cadmium Zinc Telluride (CdZnTe). Redlen Technologies developed a novel CdZnTe material, optimised for applications with high photon fluxes. Such a material was used to fabricate pixelated CdZnTe sensors with a pitch of 55 μm and 110 μm. The sensors were flip-chip bonded to Timepix ASICs and their performance was characterised at the European Synchrotron Radiation Facility (ESRF) with conventional X-ray sources and monochromatic sychrotron beams using the MAXIPIX readout system. We present results concerning the uniformity, the stability and the spatial resolution of the sensors, obtained with X-ray energies up to 60 keV

Synchrotron Radiation Computed Tomography with combined high spatial and temporal resolutions

International audienceStudying the hemodynamics in brain is of particular interest for the diagnosis, the understanding and the management of pathologies such as ischemia [1], tumors [2], and traumas [3]. For malignant glioma, it has been shown that perfusion parameters are correlated to the tumor aggressivity [4], and can be used for the treatment outcome prognosis [5]. Quantitative measurements have to be compared between various imaging days and between patients. Synchrotron Radiation Computed Tomography (SRCT) is the gold standard to measure in vivo contrast agent concentrations with high accuracy and precision owing to the characteristic of the beam and performances close to theoretical limits: high flux, nearly parallel and monochromatic x-ray beams [6,7]. In addition to being quantitative, SRCT [8] could be greatly improved with both a high temporal and spatial resolution, which we assumed would be combined using the Maxipix-CdTe detector under development at ESRF [9]. This detector features a monolithic 1 mm thick single crystal CdTe sensor (99% efficient at energies up to 60 keV) hybridised to a matrix of 3x1 Timepix chips, giving a total area of 768x256 pixels at 55 μm pitch (45 x 15 mm2). Its tomographic spatial resolution is of 0.06x0.06x0.06 mm3. The high efficiency of the detector as well as its background noise suppression enabled low dose imaging (200mGy/s). Monochromatic X-rays at 35 and 51 keV were used. 360° tomography images have been taken over 2s, 6s, and 60s. Reconstruction of the tomographic slices was conducted using PyHST package developed at ESRF. A software extension has been developed to correct for defective or unstable pixels. The results were compared to images acquired with the reference 1D germanium detector. We have successfully retrieved iodine contrast agent quantification for both steady-state protocol and dynamic contrast-enhanced perfusion imaging, with phantoms. In vivo SRCT imaging in rats bearing brain tumors also proved successful, following up the iodine uptake for 25 minutes. We foresee low dose high resolution volumic perfusion measurements, relying on enhanced frame rates and synchronization accuracy as well as improved image reconstruction techniques.References[1] Klotz E, et al., European Journal Of Radiology. 1999; 30: 170-84.[2] Eastwood JD, et al., Neuroradiology. 2003; 45: 373-6.[3] Wintermark M, et al., Radiology. 2004; 232: 211-20.[4] Roberts HC, et al., AJNR Am J Neuroradiol. 2000; 21: 891-9.[5] Cao Y, et al., International Journal Of Radiation Oncology Biology Physics. 2006; 64: 876-85.[6] Adam, J. F., H. Elleaume, et al., Journal Of Cerebral Blood Flow And Metabolism 23(4): 499-512 (2003).[7] Adam, J. F., C. Nemoz, et al., Journal Of Cerebral Blood Flow And Metabolism 25(2): 145-153 (2005).[8] Le Duc G. et al., European Radiology 10 : 1487-1492 (2000).[9] Ruat M and Ponchut C, IEEE Trans. Nucl. Sci. 59(5): 2392-2401 (2012