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Presents information on a study of how the strain relaxation of the multilayer grating evolves toward the free surface and how the local strain distribution is modulated due to the compositional profile of the layered setup. Experimental details; Fit of the experimental results; Conclusions.

Presents information on a study which investigated the vertical variation of in-plane strain induced by an InGaAs single quantum well which is embedded in a free-standing wire structure using x-ray grazing incidence diffraction. Experimental details; Theory and discussion; Conclusions.

Since in an undulator the photons add up coherently over the whole undulator length even small magnetic field errors can disturb the superposition of photons and reduce the intensity of the generated photon beam. Therefore, as in any other undulator, the magnetic field has to be measured with high accuracy. Precise measurements of the magnetic properties of conventional, i.e., permanent magnet based insertion devices (IDs) has undergone huge improvements over the past years and initiated a new era in synchrotron light sources worldwide. A similar breakthrough is now necessary in the field of superconducting insertion devices. Therefore, a part of our R&D program for superconducting insertion devices is to perform quality assessment of their magnetic field properties. [ABSTRACT FROM PUBLISHER]

Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they offer the possibility to enhance the tuning range and functionality significantly by period length switching. Period length switching can be achieved by employing two or more individually powerable subsets of superconducting coils and reverse the current in a part of the windings. [ABSTRACT FROM AUTHOR]

Accurate magnetic field measurements are a prerequisite for the characterization and optimization of undulators. The precision for measuring the magnetic properties of conventional, i.e., permanent magnet based insertion devices, has undergone tremendous improvements over the past 10 to 15 years initiating a new era in synchrotron light sources worldwide; a similar breakthrough is now necessary in the field of superconducting insertion devices. [ABSTRACT FROM AUTHOR]

In order to produce synchrotron radiation of the highest brilliance, third generation synchrotron sources make use of insertion devices (IDs). The state of the art available today for IDs is the permanent magnet technology with magnet blocks placed inside the vacuum (IVU) of the storage ring. Following an initial proposal at SPring-8 [1], the concept of Cryogenic Permanent Magnet Undulators (CPMU) is presently considered as a possible future evolution of in-vacuum undulators [2-52, 5]. Superconducting undulators (SCUs) can reach, for the same gap and period length, even higher fields than CPMU devices, allowing increases in the spectral range and the brilliance. At ANKA we are running a research and development program to develop superconducting IDs. The proof of principle of SCU technology application in a storage ring has been demonstrated at ANKA with a device developed together with the company ACCEL Instr. GmbH and installed in the ANKA storage ring since March 2005 [6]. [ABSTRACT FROM AUTHOR]

In-line phase contrast is combined with laminography to image in three dimensions regions of interest in laterally extended flat specimens of weak absorption contrast. The principle of the method and a theoretical description of the imaging process are outlined. The present instrumental implementation enables reconstructing nondestructively the internal structure at different lateral specimen positions with micron resolution. The feasibility and application potential are demonstrated for both phase-contrast and holographic (i.e., using phase retrieval) laminography by the three-dimensional imaging of fuel-cell diffusion layers. [ABSTRACT FROM AUTHOR]

Synchrotron-radiation tomography was used to investigate early foaming stages of aluminium alloys. Monochromatic radiation, high spatial resolution down to the micrometer scale, partial beam coherence, and holographic reconstruction techniques permit the distinction between different foam constituents which are not visible by other volume imaging techniques. In combination with three-dimensional image analysis, the differences in the pore initiation processes in two different aluminium alloys are shown. We find that, in powder compacts made from prealloyed AA6061 alloy powder, pores appear predominantly around the blowing agent particles whereas, in compacts made from a powder blend of Al and Si, pores tend to initiate around Si particles. [ABSTRACT FROM AUTHOR]

Computed laminography with synchrotron radiation is developed and carried out for three-dimensional imaging of flat, laterally extended objects with high spatial resolution. Particular experimental conditions of a stationary synchrotron source have been taken into account by a scanning geometry different from that employed with movable conventional laboratory x-ray sources. Depending on the mechanical precision of the sample manipulation system, high spatial resolution down to the scale of 1 μm can be attained nondestructively, even for objects of large lateral size. Furthermore, high beam intensity and the parallel-beam geometry enables easy use of monochromatic radiation for optimizing contrast and reducing imaging artifacts. Simulations and experiments on a test object demonstrate the feasibility of the method. Application to the inspection of solder joints in a flip-chip bonded device shows the potential for quality assurance of microsystem devices. [ABSTRACT FROM AUTHOR]

Examines the x-ray diffraction reciprocal space mapping of GaAs surface grating. Cross pattern of satellite rods and grating transmission substrate reflection resonance peaks; Diffraction features of monocrystalline semiconductor grating with periodicity of 574 nanometer.

In situ X-ray radiography and spatio-temporal image analysis yield quantitative information about coalescence during metal foam formation and decay. The choice of weighting every detected coalescence event by its projected area yields reliable information about the impact of coalescence on structural coarsening. The comparison of two particle-stabilized metal foams containing ceramic particles of different sizes demonstrates that the stabilization effect is provided by solid particles which are small in comparison to the average film thickness of the foamed liquid melt. [Copyright &y& Elsevier]

Babcock Noell GmbH (BNG) is completing the fabrication of a 1.5 m long superconducting insertion device for the Karlsruhe Institute of Technology (KIT). The unit is planned to be installed in the ANKA storage ring at the end of 2010 to become the light source of the new beamline NANO for high resolution X-ray diffraction. The period length of the device is 15 mm for a total of 100.5 full periods plus an additional matching period at each end. The key specifications of the system are: a K value higher than 2 for a magnetic gap of 5 mm, the capability of withstanding a 4 W beam heat load and a phase error smaller than 3.5 degrees. The superconducting coils have been qualified by means of a vertical test in liquid helium at CERN and are ready to be installed in the cryostat. This paper describes the main features of the system. [ABSTRACT FROM AUTHOR]

We investigate spatial cross-correlations between two constituents, both belonging to the same microstructure. These investigations are based on two approaches: one via the measurement of the cross-correlation function and the other uses the spatial distances between the constituents. The cross-correlation function can be measured using the fast Fourier transform, whereas the distances are determined via the Euclidean distance transform. The characteristics are derived from volume images obtained by synchrotron microtomography. As an example we consider pore formation in metallic foams, knowledge of which is important to control the foam production process. For this example, we discuss the spatial cross-correlation between the pore space and the blowing agent particles in detail. [ABSTRACT FROM AUTHOR]

Superconducting undulators and wigglers are developed for synchrotron light sources, damping rings for linear colliders and polarized positron sources. In an undulator the emitted photons along the trajectory have to interfere. In order to do so the magnetic field in all periods has to be almost identical. The field strength over one or several hundred periods is not allowed to deviate by more than 1%. Translated into mechanical accuracy the position of the wire and the poles has to be more accurate than about 5 p.m over 1 to 2 m. High quality measurement of the field is an essential requirement. In this paper we present two field measuring systems, one is under construction and another one is under design phase at the Forschungszentrum Karlsruhe. [ABSTRACT FROM AUTHOR]

Investigations of pore coalescence and individual cell wall collapse in an expanding liquid metal foam by means of X-ray radioscopy with spatio-temporal micro-resolution are reported. By using white synchrotron radiation for imaging, the rupture of a film and the subsequent merger of two neighbouring bubbles could be recorded with a time sampling rate of 40000 frames s[sup-1] (25 Its exposure time) and a spatial sampling rate of 20 μm. The rupture time of a cell wall was found to be in the range of 300 p.s. This value is in agreement with theoretical considerations which assume an inertia-dominated rupture time of cell walls in liquid metal foams. [ABSTRACT FROM AUTHOR]

In this article, we combine diffuse x-ray scattering with a Monte Carlo simulation method for the determination of the dislocation density in thin heteroepitaxial layers. As a model, we consider GaN epitaxial layers containing threading dislocations perpendicular to the surface. The densities of particular types of threading dislocations following from the comparison of measured and simulated distributions of diffusely scattered x-ray intensity are compared with the dislocation densities determined by etching. A good agreement was found. [ABSTRACT FROM AUTHOR]

An x-ray diffuse scattering investigation of p-type porous silicon (PS) is reported. Synchrotron radiation and laboratory measurements of the x-ray diffuse scattering at small and large scattering wave-vector q values are presented. At small q values and for p[sup -] -type material, small isotropic crystallites of a few nanometers diameter are shown, whereas for p[sup +]-type material the main cylindrical crystallites are larger. At large q values the fine p[sup +] PS structure is investigated and reveals the presence of small spherical crystallites around the main cylindrical crystallites. The elastic relaxation of silicon crystallites in the porous structure is also presented for oxidized and for as-formed samples, using reciprocal space maps. PS superlattice diffuse scattering is then observed. Finally, these results are discussed in relation to previous x-ray studies and other methods of structural observation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Poly-3-hydroxybutyrate (PHB) films were plasma-treated in NH 3 , Ar and NH 3 /Ar mixtures. • Surface chemistry and topography changes were observed in PHB films. • A significant decrease in contact angle and an increase in free surface energy were observed. • Fibroblast cell adhesion was significantly improved after Ar plasma treatment. Abstract Poly-3-hydroxybutyrate (PHB) films were plasma-treated using pure NH 3 , pure Ar or mixtures of the two different proportions (20%, 30%, 40%, 50%, 70% NH 3 in Ar). Surface chemistry and surface topography changes of PHB films were observed after plasma processing in all plasma regimes. The XPS results confirmed the absence of chemical modification in the case of pure Ar plasma treatment. Nitrogen-containing groups (e.g., N C O) were detected on the surfaces of P3HB films treated with NH 3 -containing plasma. The surfaces of the untreated P3HB films were hydrophobic, and plasma treatment turned the surfaces hydrophilic, irrespective of the treatment. A significant decrease in the contact angle and an increase in the free surface energy were observed. An insignificant surface ageing effect was observed when P3HB samples were exposed to air for 10 days. In NIH 3T3 mice fibroblast cells, cell adhesion was significantly improved after plasma treatment in an Ar atmosphere, which is likely related to the fact that there was a surface ξ potential of 88.6 mV at neutral pH, causing a cleavage of the polymer chains and an increase in surface roughness. [ABSTRACT FROM AUTHOR]

The enhancement of the Raman light scattering signal from the surface of the porous hybrid biocomposites based on polyhydroxybutyrate (PHB), calcium carbonate (CaCO3), and nanoplasmonic Ag particles is investigated. Based on PHB, fibrous scaffolds are obtained by the electrospinning technique. The fibrous scaffolds have been covered by CaCO3 and Ag nanoparticles by means of mineralization in salt solutions and Ag reduction reaction. Successful formation of the CaCO3 and Ag nanoparticles on the scaffold surface has been confirmed by the data of scanning electron microscopy, x-ray diffraction analysis, and infrared spectroscopy. Surface-enhanced Raman spectroscopy (SERS) of the obtained sample surface has demonstrated a significant enhancement of the Rhodamine 6G signal (Ef > 105) in comparison with the reference sample where the analyte concentration and the laser power were 100 times higher. Thus, the present research has confirmed prospects for the application of biocomposites based on polyhydroxybutyrate for detection and investigation of biomolecules by the SERS method. [ABSTRACT FROM AUTHOR]

Looks at a study which investigated the thin p- and p+ type of the porous silicon layers, using high resolution x-ray diffraction. Exhibition of the porous material's properties, with reference to the single crystal; In-depth look at the multilayers of the porous silicon; Methodology used to conduct the study; Results of the study.

Presents a study which examined the growth of Y[sub2]Co[sub17](0001) thin films on W(110) by pulsed laser deposition. Function of substrate temperature and thickness; Factors considered in the observation of different growth modes; Overview of the crystal structure of the R[sub2]Co[sub17] compounds.

In this work a double-crystal setup is employed to study compound refractive lenses made of single-crystal diamond. The point spread function of the lens is calculated taking into account the lens transmission, the wavefront aberrations, and the ultra-small-angle broadening of the X-ray beam. It is shown that, similarly to the wavefront aberrations, the ultra-small-angle scattering effects can significantly reduce the intensity gain and increase the focal spot size. The suggested approach can be particularly useful for the characterization of refractive X-ray lenses composed of many tens of unit lenses. [ABSTRACT FROM AUTHOR]

Prostate cancer (PCa) currently is the second most diagnosed cancer in men and the second most cause of cancer death after lung cancer in Western societies. This sets the necessity of modelling prostatic disorders to optimize a therapy against them. The conventional approach to investigating prostatic diseases is based on two-dimensional (2D) cell culturing. This method, however, does not provide a three-dimensional (3D) environment, therefore impeding a satisfying simulation of the prostate gland in which the PCa cells proliferate. Cryogel scaffolds represent a valid alternative to 2D culturing systems for studying the normal and pathological behavior of the prostate cells thanks to their 3D pore architecture that reflects more closely the physiological environment in which PCa cells develop. In this work the 3D morphology of three potential scaffolds for PCa cell culturing was investigated by means of synchrotron X-ray computed micro tomography (SXCμT) fitting the according requirements of high spatial resolution, 3D imaging capability and low dose requirements very well. In combination with mechanical tests, the results allowed identifying an optimal cryogel architecture, meeting the needs for a well-suited scaffold to be used for 3D PCa cell culture applications. The selected cryogel was then used for culturing prostatic lymph node metastasis (LNCaP) cells and subsequently, the presence of multi-cellular tumor spheroids inside the matrix was demonstrated again by using SXCμT. [ABSTRACT FROM AUTHOR]

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 1 m . 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. [ABSTRACT FROM AUTHOR]

A procedure for obtaining three-dimensionally resolved reciprocal-space maps in a skew X-ray diffraction geometry is described. The geometry allows tuning of the information depth in the range from tens of micrometres for symmetric skew diffraction down to tens of nanometres for strongly asymmetric skew geometries, where the angle of incidence is below the critical angle of total external reflection. The diffraction data are processed using a rotation matrix formalism. The whole three-dimensional reciprocal-space map can be measured by performing a single azimuthal rotation of the sample and using a two-dimensional detector, while keeping the angle of incidence and the X-ray information depth fixed (FIXD method). Having a high surface sensitivity under grazing-incidence conditions, the FIXD method can be applied to a large variety of Bragg reflections, particularly polar ones, which provide information on strain and chemical composition separately. In contrast with conventional grazing-incidence diffraction, the FIXD approach reveals, in addition to the lateral (in-plane) components, the vertical (out-of-plane) component of the strain field, and therefore allows the separation of the scattering contributions of strained epitaxial nanostructures by their vertical misfit. The potential of FIXD is demonstrated by resolving the diffraction signal from a single layer of InGaN quantum dots grown on a GaN buffer layer. The FIXD approach is suited to the study of free-standing and covered near-surface nano-objects, as well as vertically extended multilayer structures. [ABSTRACT FROM AUTHOR]

VN coatings were deposited by reactive sputtering at different deposition angles χ . The thin film growth was monitored by angle-dispersive in situ X-ray reflectivity measurements. These measurements were realized using a monochromatic X-ray beam and exploiting its angular divergence. Already during deposition of the first few nm, the measurements revealed the formation of a porous coating with stable growth rate. The growth rate decreased with increasing tilt angle. The reduction was less than expected from the flux projection onto the sample surface. This can only partially be explained by the porosity increase with increasing tilt angle. SIMTRA simulations confirmed that the deposition rate is strongly influenced by the interplay between deposition geo-metry and particle transport. [ABSTRACT FROM AUTHOR]

Quantitative characterization of local strain in silicon wafers is critical in view of issues such as wafer handling during manufacturing and strain engineering. In this work, full-field X-ray microdiffraction imaging using synchrotron radiation is employed to investigate the long-range distribution of strain fields in silicon wafers induced by indents under different conditions in order to simulate wafer fabrication damage. The technique provides a detailed quantitative mapping of strain and defect characterization at the micrometer spatial resolution and holds some advantages over conventional methods. [ABSTRACT FROM AUTHOR]

Europium silicide nanoislands and films with Eu coverage in the range 0.3 ML–303 ML were grown on the vicinal Si(001) surface with 4° miscut towards [110] by molecular beam epitaxy. The nanostructures were characterized by atomic force microscopy, reflection high energy electron diffraction, in situ synchrotron radiation X-ray absorption near edge structure spectroscopy and ex situ X-ray diffraction. The analysis revealed the formation of EuSi 2 with a tetragonal structure. By increasing the Eu coverage the surface morphology gradually changes from isolated islands through films with very rough surface to thick films with smoother surface. [ABSTRACT FROM AUTHOR]

In order to achieve large area semipolar GaN layers with high crystal quality, we have etched trenches into n-plane and r-plane sapphire wafers exposing c-plane-like side-walls, from which GaN stripes can be grown by metalorganic vapor phase epitaxy mainly in c -direction, forming semipolar { 10 1 ¯ 1 } or { 11 2 ¯ 2 } surfaces after coalescence. Here, we describe how to improve such layers by optimizing the side-facet orientation and by including a SiN nanomask interlayer in situ into the growth process, eventually resulting in a basal plane stacking fault density below 5 × 10 3 cm − 1 . Moreover, doping experiments have revealed a substantially lower Mg incorporation efficiency on the { 11 2 ¯ 2 } surface as compared to the c-plane, whereas Si does not show such differences. [ABSTRACT FROM AUTHOR]

We present epitaxial growth of europium (Eu) on the oxygen-induced c(6×2) reconstructed (110)Nb (niobium) surface at 150°C and at 260°C for various Eu coverages. The samples are characterized by reflection high-energy electron diffraction, atomic force microscopy and low-temperature in-situ nuclear resonance scattering. At a substrate temperature of 260°C Eu forms islands with the face-centered cubic (fcc) crystal structure that is an exotic crystallographic phase for metallic europium. The deposition at 150°C results to the already reported formation of a smooth film with hexagonal symmetry. The up to now unknown initially formed intermediate phase in this growth mode is identified as EuO-type stacking of [111]Eu layers that quickly relaxes towards that of an [0001]Eu film. The analysis of the nuclear resonance scattering data unambiguously demonstrates the formation of EuO interface at 260°C that facilitates the stabilization of the strained fcc Eu lattice. No traces of EuO are found in the sample grown at 150°C. [ABSTRACT FROM AUTHOR]

The retrieval of spatially resolved atomic displacements is investigated via the phases of the direct(real)-space image reconstructed from the strained crystal's coherent X-ray diffraction pattern. It is demonstrated that limiting the spatial variation of the first- and second-order spatial displacement derivatives improves convergence of the iterative phase-retrieval algorithm for displacements reconstructions to the true solution. This approach is exploited to retrieve the displacement in a periodic array of silicon lines isolated by silicon dioxide filled trenches. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a group of Lu2SiO5:Tb (LSO:Tb) scintillating layers with a Tb concentration between 8% and 19% were investigated by means of synchrotron and laboratory techniques. The scintillation efficiency measurements proved that the highest light yield is obtained for a Tb concentration equal to 15%. At higher concentration, quenching processes occur which lower the light emission. The analysis of the reciprocal space maps of the (082) (280) and (040) Bragg reflections showed that LSO:Tb epilayers are well adapted on YbSO substrates for all the investigated concentrations. The spatial resolution tests demonstrated the possibility to achieve a resolution of 1 μm with a 6 μm thick scintillating layer. [Copyright &y& Elsevier]

Polymers are one of the most interesting classes of materials for bioengineering due to their high biocompatibility and the possibility of regulating their strength and degradation. In bioengineering, the design of a polymer scaffold determines the functional possibilities of the scaffold and its possible medical applications. Traditionally, the design of polymer scaffolds is analyzed with the help of two-dimensional visualization methods, such as optical and electron microscopy, and computer tomography. However, the x-ray region of the electromagnetic spectrum is only insignificantly absorbed by polymers and soft tissue, which means that it does not support computer tomography with sufficient contrast. The present work investigates visualization with the help of an interferometer based on the Talbot effect for three-dimensional visualization of a polymer scaffold in absorption, phase, and dark-field contrasts. A comparison of images obtained by x-ray visualization with histological sections of the scaffold is made. Phase contrast has made it possible to visualize the polymer structure and growth of soft tissues in the volume of the scaffold. In the future, it will be possible to use phase contrast for three-dimensional visualization of polymer scaffolds and soft tissues in vivo as well as in vitro. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we present preliminary in-line X-ray lensless projection imaging results at a synchrotron facility by using novel solid-state detectors based on non-destructive readout of photoluminescent colour centres in lithium fluoride thin films. The peculiarities of LiF radiation detectors are high spatial resolution on a large field of view, wide dynamic range, versatility and simplicity of use. These properties offered the opportunity to test a broadband X-ray synchrotron source for lensless projection imaging experiments at the TopoTomo beamline of the ANKA synchrotron facility by using a white beam spectrum (3–40 keV). Edge-enhancement effects were observed for the first time on a test object; they are discussed and compared with simulations, on the basis of the colour centre photoluminescence linear response found in the investigated irradiation conditions. [Copyright &y& Elsevier]

Abstract: Novel X-ray imaging detectors based on photoluminescence of colour centres in lithium fluoride (LiF) have been proposed and tested for extreme ultraviolet, soft and hard X-rays up to 10keV. For the first time we present the optical characterisation of LiF crystals and thin films irradiated at the TOPO–TOMO beamline of synchroton light source Anka (Karlsruhe, Germany) in the energy range 6–40keV for different exposure times. Absorption and photoluminescence spectra were analysed to study the optical response of the LiF-based detectors. High resolved X-ray imaging of commercial test patterns has been obtained on LiF crystals and films by optical readout with a confocal laser scanning fluorescence microscope. [Copyright &y& Elsevier]

While channel-cut crystals, in which the diffracting surfaces in an asymmetric cut are kept parallel, can provide beam collimation and spectral beam shaping, they can in addition provide beam compression or expansion if the cut is V-shaped. The compression/expansion ratio depends in this case on the total asymmetry factor. If the Ge(220) diffraction planes and a total asymmetry factor in excess of 10 are used, the rocking curves of two diffractors will have a sufficient overlap only if the second diffractor is tuned slightly with respect to the first one. This study compares and analyses several ways of overcoming this mismatch, which is due to refraction, when the Cu Kα1 beam is compressed 21-fold in a V21 monochromator. A more than sixfold intensity increase was obtained if the matching was improved either by a compositional variation or by a thermal deformation. This provided an intensity gain compared with the use of a simple slit in a symmetrical channel-cut monochromator. The first attempt to overcome the mismatch by introducing different types of X-ray prisms for the required beam deflection is described as well. The performance of the V-shaped monochromators is demonstrated in two applications. A narrow collimated monochromatic beam obtained in the beam compressing mode was used for high-resolution grazing-incidence small-angle X-ray scattering measurements of a silicon sample with corrupted surface. In addition, a two-dimensional Bragg magnifier, based on two crossed V15 channel monochromators in beam expansion mode and tuned by means of unequal asymmetries, was successfully applied to high-resolution imaging of test structures in combination with a Medipix detector. [ABSTRACT FROM AUTHOR]

Abstract: High resolution X-ray coplanar (symmetric X-ray diffraction (SXRD) and asymmetric X-ray diffraction (ASXRD)) and non-coplanar diffraction (grazing incidence diffraction (GID)) have been used to investigate the quality of AlGaN epilayers with 20% Al content, grown on sapphire using SiN x interlayers. The measurement of reciprocal space maps (RSM) with higher orders of reflections of SXRD and ASXRD which is readily performed at the synchrotron with high resolution and intensity reveals the presence of several diffraction peaks originating from the occurrence of local differences in the lattice constants. Two distinguishable AlGaN phases having different crystalline parameters were clearly recognized from X-ray data and the corresponding densities of screw dislocations have been determined measured as function of the overgrowth thickness varying from 0.5μm to 3.5μm. The variation of the screw and edge type dislocation densities with the overgrowth thickness has been found to follow the scaling law h −n where h is the thickness of the buffer layer. [Copyright &y& Elsevier]

Abstract: Semi-solid melts exhibit a very unpredictable rheology and filling dynamics, when injected into thin-walled components. Optimization of the process requires an insight into the casting process during injection. For this purpose we injected semi-solid an Al–Ge alloy into two different thin channel geometries while recording high resolution radiographs at fast frame rates (up to 1000 images per s). Comparison of a bottleneck channel, which has previously been used for slower experiments, with a right-angle turn geometry reveals a significant influence of the channel shape on the flow behaviour of the particle–liquid mixture. While the bottleneck is quickly sealed with densified solid, turbulences in the right-angle turn apparently permit solid particles and clusters to move conjointly with the liquid and thus achieve a more complete filling. Single particle trajectories and rapid break-up of solid skeletons in such a system have been observed for the first time in situ. [Copyright &y& Elsevier]

Abstract: Tomographic imaging using both laboratory sources and synchrotron radiation (SR) was performed to achieve a multi-scale damage assessment of carbon fibre composites subjected to impact damage, allowing various internal damage modes to be studied in three-dimensions. The focus of this study is the comparison of different tomographic methods, identifying their capabilities and limitations, and their use in a complementary manner for creating an overall 3D damage assessment at both macroscopic and microscopic levels. Overall, microfocus laboratory computed tomography (μCT) offers efficient routine assessment of damage at mesoscopic and macroscopic levels in engineering-scale test coupons and relatively high spatial resolutions on trimmed-down samples; whilst synchrotron radiation computed tomography (SRCT) and computed laminography (SRCL) offer scans with the highest image quality, particularly given the short acquisition times, allowing damage micromechanisms to be studied in detail. [Copyright &y& Elsevier]

High-resolution X-ray diffraction in coplanar and noncoplanar geometries has been used to investigate the influence of an SiN x nano-mask in the reduction of the threading dislocation (TD) density of high-quality AlGaN epitaxial layers grown on sapphire substrates. Our developed model, based on a Monte Carlo method, was applied to the simulation of the reciprocal-space maps of a two-layer system. Good agreement was found between the simulation and the experimental data, leading to an accurate determination of the dislocation densities as a function of the overgrowth layer thickness. The efficiency of the SiN x nano-mask was defined as the ratio of the TD densities in the AlGaN layers below and above the mask. A significant improvement in the AlGaN layer quality was achieved by increasing the overgrowth layer thickness, and a TD density reduction scaling law was established. [ABSTRACT FROM AUTHOR]

Synchrotron radiation laminography with X-ray diffraction contrast enables three-dimensional imaging of dislocations in monocrystalline wafers. We outline the principle of the technique, the required experimental conditions, and the reconstruction procedure. The feasibility and the potential of the method are demonstrated by three-dimensional imaging of dislocation loops in an indent-damaged and annealed silicon wafer. [ABSTRACT FROM AUTHOR]

A portable synchrotron molecular beam epitaxy (MBE) system is designed and applied for in situ investigations. The growth chamber is equipped with all the standard MBE components such as effusion cells with shutters, main shutter, cooling shroud, manipulator, reflection high energy electron diffraction setup, and pressure gauges. The characteristic feature of the system is the beryllium windows which are used for in situ x-ray measurements. An UHV sample transfer case allows in vacuo transfer of samples prepared elsewhere. We describe the system design and demonstrate its performance by investigating the annealing process of buried InGaAs self-organized quantum dots. [ABSTRACT FROM AUTHOR]

Abstract: Experimental data are presented on the structure and properties of hardening nanocrystalline copper-added titanium nitride coatings produced by plasma-assisted vacuum arc evaporation of sintered cathodes. A model of the nanostructurization of this type of coating is proposed. According to the model, the nanocrystallization in these materials is due to the added atoms, which form an amorphous sheath around a grain that restricts the grain growth. [Copyright &y& Elsevier]

Abstract: Titanium beryllide Be12Ti and vanadium beryllide Be12V are considered to be promising materials for advanced neutron multipliers in the helium-cooled breeding blanket of DEMO reactor. A study of the surface layers of oxidized beryllide specimens by means of powder X-ray diffraction technique is presented in this work. The phase composition of the near-to-surface layers of Be12Ti and Be12V specimens was investigated at the Single Crystal Diffraction (SCD) beamline at ANKA synchrotron facility after air-annealing at 800°C. A high surface sensitivity of measurements was achieved at grazing incidence conditions by varying the incidence angle. Since beryllium has low values of X-ray absorption, the near-surface regions having depths from 2 up to 20μm were investigated. The main objective of the work is the evaluation of composition of the reactant products which can influence the parameters of retention and release of radiogenic gases. [Copyright &y& Elsevier]

Abstract: Self-organized, buried InAs quantum dots covered by an AlAs diffusion barrier were investigated under UHV conditions using grazing incidence X-ray diffraction. The experimental data is compared to the simulated results obtained by Finite Element Method and Distorted Wave Born Approximation. We have found that the simulated data could be compared to the experimental one only after convolution by the resolution element which can be estimated from the experiment. By adjusting the simulation parameters we were able to find good agreement between the simulated and the measured data. [Copyright &y& Elsevier]

Abstract: During the last years the electron beams produced by Laser-Plasma Accelerators were used for the first time to generate synchrotron radiation in an undulator. Both the emittance and especially the energy spread of a laser plasma accelerator beam are significantly larger than the emittance and the energy spread of beams from conventional accelerators. Beams with a high energy spread produce in a conventional undulator photon beams with a high wavelength spread. In this paper a novel modified undulator design is presented which can reduce the energy spread of the photon beam caused by the energy spread of the electron beam. The magnetic concept is analysed in detail by tracking test electrons through the device. An experiment to test this concept is in preparation. [Copyright &y& Elsevier]

Characterization of the microstructure of thermal barrier coatings (TBCs) is essential for assessing coating lifetime and for understanding the damage mechanisms leading to ceramic layer spallation. Recent progress in synchrotron-radiation computed laminography (SRCL) enables imaging of samples that are thin but extended in two dimensions. This study reports on the first results of the 3-D characterization of electron beam–physical vapour deposition TBCs by SRCL. Image analysis was very helpful in investigating the 3-D microstructure obtained and is also described. [ABSTRACT FROM AUTHOR]