Synchrotron-radiation-based X-ray micro-computed tomography reveals dental bur debris under dental composite restorations
Dental burs are used extensively in dentistry to mechanically prepare tooth structures for restorations (fillings), yet little has been reported on the bur debris left behind in the teeth, and whether it poses potential health risks to patients. Here it is aimed to image dental bur debris under dental fillings, and allude to the potential health hazards that can be caused by this debris when left in direct contact with the biological surroundings, specifically when the debris is made of a non-biocompatible material. Non-destructive micro-computed tomography using the BioMedical Imaging & Therapy facility 05ID-2 beamlin...
Source: Journal of Synchrotron Radiation - March 21, 2016 Category: Physics Authors: Hedayat, A.Nagy, N.Packota, G.Monteith, J.Allen, D.Wysokinski, T.Zhu, N. Tags: in-line phase contrast imaging micro-computed tomography dental bur debris composite resin dental filling tungsten carbide – cobalt dentinal tubule dentinal fluid research papers Source Type: research
Hybrid pixel array detectors enter the low noise regime
(Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 25, 2016 Category: Physics Authors: Graafsma, H. Tags: detectors hybrid pixel array detectors HPADs low-noise detectors scientific commentaries Source Type: research
Optimization of the design for beamline with fast polarization switching elliptically polarized undulators
Fast switching of X-ray polarization with a lock-in amplifier is a good method for acquiring weak signals from background noise for X-ray magnetic circular dichroism (XMCD) experiments. The usual way to obtain a beam with fast polarization switching is to use two series of elliptically polarized undulators (tandem twin EPUs). The two EPUs generate two individual beams. Each beam has a different polarization and is fast switched into the beamline. It is very important to ensure that the energy resolution, the flux and the spot size at the sample of the two beams are equal in XMCD experiments. However, it is difficult in bea...
Source: Journal of Synchrotron Radiation - February 20, 2016 Category: Physics Authors: Cao, J.Wang, Y.Zou, Y.Zhang, X.Wu, Y.Tai, R. Tags: soft X-ray magnetic circular dichroism beamline fast polarization switching tandem twin elliptically polarized undulators energy resolution research papers Source Type: research
A modified discrete algebraic reconstruction technique for multiple grey image reconstruction for limited angle range tomography
The `missing wedge', which is due to a restricted rotation range, is a major challenge for quantitative analysis of an object using tomography. With prior knowledge of the grey levels, the discrete algebraic reconstruction technique (DART) is able to reconstruct objects accurately with projections in a limited angle range. However, the quality of the reconstructions declines as the number of grey levels increases. In this paper, a modified DART (MDART) was proposed, in which each independent region of homogeneous material was chosen as a research object, instead of the grey values. The grey values of each discrete region w...
Source: Journal of Synchrotron Radiation - February 20, 2016 Category: Physics Authors: Liang, Z.Guan, Y.Liu, G.Chen, X.Li, F.Guo, P.Tian, Y. Tags: modified discrete algebraic reconstruction technique (MDART) multiple grey image image reconstruction limited-angle range research papers Source Type: research
The high-field magnet endstation for X-ray magnetic dichroism experiments at ESRF soft X-ray beamline ID32
A new high-field magnet endstation for X-ray magnetic dichroism experiments has been installed and commissioned at the ESRF soft X-ray beamline ID32. The magnet consists of two split-pairs of superconducting coils which can generate up to 9 T along the beam and up to 4 T orthogonal to the beam. It is connected to a cluster of ultra-high-vacuum chambers that offer a comprehensive set of surface preparation and characterization techniques. The endstation and the beam properties have been designed to provide optimum experimental conditions for X-ray magnetic linear and circular dichroism experiments in the soft X-ray rang...
Source: Journal of Synchrotron Radiation - February 20, 2016 Category: Physics Authors: Kummer, K.Fondacaro, A.Jimenez, E.Velez-Fort, E.Amorese, A.Aspbury, M.Yakhou-Harris, F.van der Linden, P.Brookes, N.B. Tags: high-field magnet endstation ID32 ESRF sample preparation XMCD XMLD research papers Source Type: research
FDMX: extended X-ray absorption fine structure calculations using the finite difference method
A new theoretical approach and computational package, FDMX, for general calculations of X-ray absorption fine structure (XAFS) over an extended energy range within a full-potential model is presented. The final-state photoelectron wavefunction is calculated over an energy-dependent spatial mesh, allowing for a complete representation of all scattering paths. The electronic potentials and corresponding wavefunctions are subject to constraints based on physicality and self-consistency, allowing for accurate absorption cross sections in the near-edge region, while higher-energy results are enabled by the implementation of eff...
Source: Journal of Synchrotron Radiation - February 18, 2016 Category: Physics Authors: Bourke, J.D.Chantler, C.T.Joly, Y. Tags: X-ray absorption finite difference methods fine structure XAFS FDMNES FDMX research papers Source Type: research
Novel micro-reactor flow cell for investigation of model catalysts using in situ grazing-incidence X-ray scattering
The design, fabrication and performance of a novel and highly sensitive micro-reactor device for performing in situ grazing-incidence X-ray scattering experiments of model catalyst systems is presented. The design of the reaction chamber, etched in silicon on insulator (SIO), permits grazing-incidence small-angle X-ray scattering (GISAXS) in transmission through 10 µm-thick entrance and exit windows by using micro-focused beams. An additional thinning of the Pyrex glass reactor lid allows simultaneous acquisition of the grazing-incidence wide-angle X-ray scattering (GIWAXS). In situ experiments at synchrotron facil...
Source: Journal of Synchrotron Radiation - February 18, 2016 Category: Physics Authors: Kehres, J.Pedersen, T.Masini, F.Andreasen, J.W.Nielsen, M.M.Diaz, A.Nielsen, J.H.Hansen, O.Chorkendorff, I. Tags: in situ GISAXS GIWAXS micro-reactor research papers Source Type: research
Analysis and control of the photon beam position at PLS-II
At third-generation light sources, the photon beam position stability is a critical issue for user experiments. In general, photon beam position monitors are developed to detect the real photon beam position, and the position is controlled by a feedback system in order to maintain the reference photon beam position. At Pohang Light Source II, a photon beam position stability of less than 1 µm r.m.s. was achieved for a user service period in the beamline, where the photon beam position monitor is installed. Nevertheless, a detailed analysis of the photon beam position data was necessary in order to ensure the perfor...
Source: Journal of Synchrotron Radiation - February 18, 2016 Category: Physics Authors: Ko, J.Kim, I.-Y.Kim, C.Kim, D.-T.Huang, J.-Y.Shin, S. Tags: photon beam position monitor stability SVD analysis research papers Source Type: research
Densitometry and temperature measurement of combustion gas by X-ray Compton scattering
Measurement of combustion gas by high-energy X-ray Compton scattering is reported. The intensity of Compton-scattered X-rays has shown a position dependence across the flame of the combustion gas, allowing us to estimate the temperature distribution of the combustion flame. The energy spectra of Compton-scattered X-rays have revealed a significant difference across the combustion reaction zone, which enables us to detect the combustion reaction. These results demonstrate that high-energy X-ray Compton scattering can be employed as an in situ technique to probe inside a combustion reaction. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Sakurai, H.Kawahara, N.Itou, M.Tomita, E.Suzuki, K.Sakurai, Y. Tags: Compton scattering laminar flame imaging temperature combustion reaction research papers Source Type: research
Compound refractive lenses as prefocusing optics for X-ray FEL radiation
The performance of X-ray free-electron laser beamlines may be limited by the angular aperture. Compound refractive lenses (CRLs) can be employed to prefocus the X-ray beam, thereby increasing the beamline transmission. A prefocusing CRL was implemented in the X-ray transport of the Matter under Extreme Conditions Instrument at the Linac Coherent Light Source. A significant improvement in the beamline transmission was calculated over the 3–10 keV photon energy range. At 5 keV, the relative X-ray intensity was measured and a factor of four increase was seen in the beamline transmission. The X-ray focus was also det...
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Heimann, P.MacDonald, M.Nagler, B.Lee, H.J.Galtier, E.Arnold, B.Xing, Z. Tags: compound refractive lens X-ray free-electron laser X-ray optics research papers Source Type: research
Observation of scissors modes in solid state systems with a SQUID
The occurrence of scissors modes in crystals that have deformed ions in their unit cells was predicted some time ago. The theoretical value of their energy is rather uncertain, however, ranging between ten and a few tens of eV, with the corresponding widths of 10−7 to 10−6 eV. Their observation by resonance fluorescence experiments therefore requires a photon spectrometer covering a wide energy range with a very high resolving power. Here, a new experiment is proposed and discussed in which such difficulties are overcome by measuring with a superconducting quantum interference device (SQUID) the variation of ...
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Hatada, K.Hayakawa, K.Palumbo, F.Marcelli, A. Tags: rotor model of deformed ions scissors modes SQUID collective magnetic excitations research papers Source Type: research
Rapid in situ X-ray position stabilization via extremum seeking feedback
X-ray beam stability is crucial for acquiring high-quality data at synchrotron beamline facilities. When the X-ray beam and defining apertures are of similar dimensions, small misalignments driven by position instabilities give rise to large intensity fluctuations. This problem is solved using extremum seeking feedback control (ESFC) for in situ vertical beam position stabilization. In this setup, the intensity spatial gradient required for ESFC is determined by phase comparison of intensity oscillations downstream from the sample with pre-existing vertical beam oscillations. This approach compensates for vertical position...
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Zohar, S.Venugopalan, N.Kissick, D.Becker, M.Xu, S.Makarov, O.Stepanov, S.Ogata, C.Sanishvili, R.Fischetti, R.F. Tags: extremum seeking stabilization feedback X-rays research papers Source Type: research
Temperature-dependent EXAFS study of the local structure and lattice dynamics in cubic Y2O3
The local structure and lattice dynamics in cubic Y2O3 were studied at the Y K-edge by X-ray absorption spectroscopy in the temperature range from 300 to 1273 K. The temperature dependence of the extended X-ray absorption fine structure was successfully interpreted using classical molecular dynamics and a novel reverse Monte Carlo method, coupled with the evolutionary algorithm. The obtained results allowed the temperature dependence of the yttria atomic structure to be followed up to ∼6 Å and to validate two force-field models. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 17, 2016 Category: Physics Authors: Jonane, I.Lazdins, K.Timoshenko, J.Kuzmin, A.Purans, J.Vladimirov, P.Gräning, T.Hoffmann, J. Tags: EXAFS molecular dynamics reverse Monte Carlo evolutionary algorithm yttria research papers Source Type: research
The LUCIA beamline at SOLEIL
Commissioned in May 2004 on the SLS machine, the LUCIA beamline was moved to the synchrotron SOLEIL during the summer of 2008. To take advantage of this new setting several changes to its design were introduced. Here, a review of the various improvements of the mechanics and, mostly, of the optics is given. Described in detail are the results of a new multilayer grating monochromator implemented on the Kohzu vessel already holding the two-crystal set-up. It consists of a grating grooved onto a multilayer (replacing the first crystal) associated to a multilayer (as a second crystal). It allows a shift of the low-energy limi...
Source: Journal of Synchrotron Radiation - February 13, 2016 Category: Physics Authors: Vantelon, D.Trcera, N.Roy, D.Moreno, T.Mailly, D.Guilet, S.Metchalkov, E.Delmotte, F.Lassalle, B.Lagarde, P.Flank, A.-M. Tags: X-ray spectrocopy beamline multilayer grating monochromator microspectroscopy beamlines Source Type: research
Protein crystallography beamline (PX-BL21) at Indus-2 synchrotron
The protein crystallography beamline (PX-BL21), installed at the 1.5 T bending-magnet port at the Indian synchrotron (Indus-2), is now available to users. The beamline can be used for X-ray diffraction measurements on a single crystal of macromolecules such as proteins, nucleic acids and their complexes. PX-BL21 has a working energy range of 5–20 keV for accessing the absorption edges of heavy elements commonly used for phasing. A double-crystal monochromator [Si(111) and Si(220)] and a pair of rhodium-coated X-ray mirrors are used for beam monochromatization and manipulation, respectively. This beamline is equip...
Source: Journal of Synchrotron Radiation - February 13, 2016 Category: Physics Authors: Kumar, A.Ghosh, B.Poswal, H.K.Pandey, K.K.JagannathHosur, M.V.Dwivedi, A.Makde, R.D.Sharma, S.M. Tags: protein crystallography beamline bending magnet Indus-2 beamlines Source Type: research
Perspectives and limitations of symmetric X-ray Bragg reflections for inspecting polytypism in nanowires
X-ray diffraction, possibly time-resolved during growth or annealing, is an important technique for the investigation of polytypism in free-standing nanowires. A major advantage of the X-ray diffraction approach for adequately chosen beam conditions is its high statistical significance in comparison with transmission electron microscopy. In this manuscript the interpretation of such X-ray intensity distribution is discussed, and is shown to be non-trivial and non-unique given measurements of the c or c reflection of polytypic nanowires grown in the (111)c direction. In particular, the diffracted intensity distrib...
Source: Journal of Synchrotron Radiation - February 13, 2016 Category: Physics Authors: Köhl, M.Schroth, P.Baumbach, T. Tags: diffraction nanowires GaAs polytypism research papers Source Type: research
Visualization of microvasculature and thrombi by X-ray phase-contrast computed tomography in hepatocellular carcinoma
In conclusion, PCCT can clearly show the three-dimensional subtle structures of HCC that cannot be detected by conventional absorption-based computed tomography and provides a new method for the imageology of HCC. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 12, 2016 Category: Physics Authors: Jian, J.Yang, H.Zhao, X.Xuan, R.Zhang, Y.Li, D.Hu, C. Tags: hepatocellular carcinoma (HCC) microvasculature thrombus phase-contrast computed tomography (PCCT) research papers Source Type: research
In situ synchrotron X-ray powder diffraction for studying the role of induced structural defects on the thermoluminescence mechanism of nanocrystalline LiF
The correlation between the thermoluminescence (TL) response of nanocrystalline LiF and its microstructure was studied. To investigate the detailed TL mechanism, the glow curves of nanocrystalline LiF samples produced by high-energy ball-milling were analyzed. The microstructure of the prepared samples was analyzed by synchrotron X-ray powder diffraction (XRPD) at room temperature. Then, the microstructure of a representative pulverized sample was investigated in detail by performing in situ XRPD in both isothermal and non-isothermal modes. In the present study, the dislocations produced by ball-milling alter the microstru...
Source: Journal of Synchrotron Radiation - February 12, 2016 Category: Physics Authors: El Ashmawy, M.Amer, H.Abdellatief, M. Tags: synchrotron diffraction thermoluminescence dislocation density kinetics nanocrystalline microstructure research papers Source Type: research
Ultra-high-resolution inelastic X-ray scattering at high-repetition-rate self-seeded X-ray free-electron lasers
Inelastic X-ray scattering (IXS) is an important tool for studies of equilibrium dynamics in condensed matter. A new spectrometer recently proposed for ultra-high-resolution IXS (UHRIX) has achieved 0.6 meV and 0.25 nm−1 spectral and momentum-transfer resolutions, respectively. However, further improvements down to 0.1 meV and 0.02 nm−1 are required to close the gap in energy–momentum space between high- and low-frequency probes. It is shown that this goal can be achieved by further optimizing the X-ray optics and by increasing the spectral flux of the incident X-ray pulses. UHRIX performs best at...
Source: Journal of Synchrotron Radiation - February 12, 2016 Category: Physics Authors: Chubar, O.Geloni, G.Kocharyan, V.Madsen, A.Saldin, E.Serkez, S.Shvyd'ko, Y.Sutter, J. Tags: inelastic X-ray scattering X-ray free-electron laser X-ray optics research papers Source Type: research
Studying solutions at high shear rates: a dedicated microfluidics setup
The development of a dedicated small-angle X-ray scattering setup for the investigation of complex fluids at different controlled shear conditions is reported. The setup utilizes a microfluidics chip with a narrowing channel. As a consequence, a shear gradient is generated within the channel and the effect of shear rate on structure and interactions is mapped spatially. In a first experiment small-angle X-ray scattering is utilized to investigate highly concentrated protein solutions up to a shear rate of 300000 s−1. These data demonstrate that equilibrium clusters of lysozyme are destabilized at high shear rates. ...
Source: Journal of Synchrotron Radiation - February 12, 2016 Category: Physics Authors: Wieland, D.C.F.Garamus, V.M.Zander, T.Krywka, C.Wang, M.Dedinaite, A.Claesson, P.M.Willumeit-Römer, R. Tags: shear complex solutions small-angle X-ray scattering (SAXS) microfluidics lysozyme aggregation rheology protein interaction beamline setup research papers Source Type: research
Non-negative matrix factorization for the near real-time interpretation of absorption effects in elemental distribution images acquired by X-ray fluorescence imaging
Elemental distribution images acquired by imaging X-ray fluorescence analysis can contain high degrees of redundancy and weakly discernible correlations. In this article near real-time non-negative matrix factorization (NMF) is described for the analysis of a number of data sets acquired from samples of a bi-modal α+β Ti-6Al-6V-2Sn alloy. NMF was used for the first time to reveal absorption artefacts in the elemental distribution images of the samples, where two phases of the alloy, namely α and β, were in superposition. The findings and interpretation of the NMF results were confirmed by Monte Carlo ...
Source: Journal of Synchrotron Radiation - February 11, 2016 Category: Physics Authors: Alfeld, M.Wahabzada, M.Bauckhage, C.Kersting, K.Wellenreuther, G.Barriobero-Vila, P.Requena, G.Boesenberg, U.Falkenberg, G. Tags: micro-XRF data analysis non-negative matrix factorization NMF Ti alloys research papers Source Type: research
First experimental feasibility study of VIPIC: a custom-made detector for X-ray speckle measurements
The Vertically Integrated Photon Imaging Chip (VIPIC) was custom-designed for X-ray photon correlation spectroscopy, an application in which occupancy per pixel is low but high time resolution is needed. VIPIC operates in a sparsified streaming mode in which each detected photon is immediately read out as a time- and position-stamped event. This event stream can be fed directly to an autocorrelation engine or accumulated to form a conventional image. The detector only delivers non-zero data (sparsified readout), greatly reducing the communications overhead typical of conventional frame-oriented detectors such as charge-cou...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Rumaiz, A.K.Siddons, D.P.Deptuch, G.Maj, P.Kuczewski, A.J.Carini, G.A.Narayanan, S.Dufresne, E.M.Sandy, A.Bradford, R.Fluerasu, A.Sutton, M. Tags: VIPIC XPCS detectors research papers Source Type: research
Spontaneous emission and spectral properties of radiation by relativistic electrons in a gyro-klystron and optical-klystron undulator
In this paper spontaneous emission of radiation by relativistic electrons in a gyro-klystron is studied. The scheme consists of two solenoid sections separated by a dispersive section. In the dispersive section the electrons are made non-resonant with the radiation. The dispersive section transforms a small change of the velocity into changes of the phases of the electrons. This leads to enhanced radiation due to klystron-type modulation as compared with a conventional gyrotron-type device driven by cyclotron maser interaction. It is shown that the klystron-modulated spectrum depends on the dispersive field strength, finit...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Prakash, B.Mishra, G.Khullar, R. Tags: undulator klystron gyrotron undulator radiation research papers Source Type: research
Calibrating the X-ray attenuation of liquid water and correcting sample movement artefacts during in operando synchrotron X-ray radiographic imaging of polymer electrolyte membrane fuel cells
Synchrotron X-ray radiography, due to its high temporal and spatial resolutions, provides a valuable means for understanding the in operando water transport behaviour in polymer electrolyte membrane fuel cells. The purpose of this study is to address the specific artefact of imaging sample movement, which poses a significant challenge to synchrotron-based imaging for fuel cell diagnostics. Specifically, the impact of the micrometer-scale movement of the sample was determined, and a correction methodology was developed. At a photon energy level of 20 keV, a maximum movement of 7.5 µm resulted in a false water thic...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Ge, N.Chevalier, S.Hinebaugh, J.Yip, R.Lee, J.Antonacci, P.Kotaka, T.Tabuchi, Y.Bazylak, A. Tags: synchrotron radiography sample movement water attenuation coefficient calibration polymer electrolyte membrane fuel cells Beer – Lambert law research papers Source Type: research
Towards hybrid pixel detectors for energy-dispersive or soft X-ray photon science
JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications at free-electron lasers and synchrotron light sources. The JUNGFRAU 0.4 prototype presented here is specifically geared towards low-noise performance and hence soft X-ray detection. The design, geometry and readout architecture of JUNGFRAU 0.4 correspond to those of other JUNGFRAU pixel detectors, which are charge-integrating detectors with 75 µm × 75 µm pixels. Main characteristics of JUNGFRAU 0.4 are its fixed gain and r.m.s. noise of as low as 27 e−...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Jungmann-Smith, J.H.Bergamaschi, A.Brückner, M.Cartier, S.Dinapoli, R.Greiffenberg, D.Huthwelker, T.Maliakal, D.Mayilyan, D.Medjoubi, K.Mezza, D.Mozzanica, A.Ramilli, M.Ruder, C.Schädler, L.Schmitt, B.Shi, X.Tinti, G. Tags: hybrid detectors soft X-rays energy-dispersive detectors instrumentation for FELs instrumentation for synchrotrons research papers Source Type: research
Optimized spatial overlap in optical pump–X-ray probe experiments with high repetition rate using laser-induced surface distortions
Ultrafast X-ray diffraction experiments require careful adjustment of the spatial overlap between the optical excitation and the X-ray probe pulse. This is especially challenging at high laser repetition rates. Sample distortions caused by the large heat load on the sample and the relatively low optical energy per pulse lead to only tiny signal changes. In consequence, this results in small footprints of the optical excitation on the sample, which turns the adjustment of the overlap difficult. Here a method for reliable overlap adjustment based on reciprocal space mapping of a laser excited thin film is presented. (Source:...
Source: Journal of Synchrotron Radiation - February 10, 2016 Category: Physics Authors: Reinhardt, M.Koc, A.Leitenberger, W.Gaal, P.Bargheer, M. Tags: ultrafast X-ray diffraction nanostructures surface deformation heat diffusion optical pump research papers Source Type: research
3D-printed photo-spectroelectrochemical devices for in situ and in operando X-ray absorption spectroscopy investigation
Three-dimensional printed multi-purpose electrochemical devices for X-ray absorption spectroscopy are presented in this paper. The aim of this work is to show how three-dimensional printing can be a strategy for the creation of electrochemical cells for in situ and in operando experiments by means of synchrotron radiation. As a case study, the description of two cells which have been employed in experiments on photoanodes for photoelectrochemical water splitting are presented. The main advantages of these electrochemical devices are associated with their compactness and with the precision of the three-dimensional printing ...
Source: Journal of Synchrotron Radiation - February 2, 2016 Category: Physics Authors: Achilli, E.Minguzzi, A.Visibile, A.Locatelli, C.Vertova, A.Naldoni, A.Rondinini, S.Auricchio, F.Marconi, S.Fracchia, M.Ghigna, P. Tags: 3D printing in situ and in operando XAS photo-electrochemistry compact environmental cells photoanodic reactions short communications Source Type: research
The stopped-drop method: a novel setup for containment-free and time-resolved measurements
A novel setup for containment-free time-resolved experiments at a free-hanging drop is reported. Within a dead-time of 100 ms a drop of mixed reactant solutions is formed and the time evolution of a reaction can be followed from thereon by various techniques. As an example, a small-angle X-ray scattering study on the formation mechanism of EDTA-stabilized CdS both at a synchrotron and a laboratory X-ray source is presented here. While the evolution can be followed with one drop only at a synchrotron source, a stroboscopic mode with many drops is preferable for the laboratory source. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - February 2, 2016 Category: Physics Authors: Schiener, A.Seifert, S.Magerl, A. Tags: in situ containment-free millisecond time-resolved sample environment SAXS research papers Source Type: research
Transmission X-ray scattering as a probe for complex liquid-surface structures
The need for functional materials calls for increasing complexity in self-assembly systems. As a result, the ability to probe both local structure and heterogeneities, such as phase-coexistence and domain morphologies, has become increasingly important to controlling self-assembly processes, including those at liquid surfaces. The traditional X-ray scattering methods for liquid surfaces, such as specular reflectivity and grazing-incidence diffraction, are not well suited to spatially resolving lateral heterogeneities due to large illuminated footprint. A possible alternative approach is to use scanning transmission X-ray s...
Source: Journal of Synchrotron Radiation - February 2, 2016 Category: Physics Authors: Fukuto, M.Yang, L.Nykypanchuk, D.Kuzmenko, I. Tags: transmission X-ray scattering liquid surface scattering SAXS WAXS air/water interface research papers Source Type: research
Reference spectra of important adsorbed organic and inorganic phosphate binding forms for soil P speciation using synchrotron-based K-edge XANES spectroscopy
Direct speciation of soil phosphorus (P) by linear combination fitting (LCF) of P K-edge XANES spectra requires a standard set of spectra representing all major P species supposed to be present in the investigated soil. Here, available spectra of free- and cation-bound inositol hexakisphosphate (IHP), representing organic P, and of Fe, Al and Ca phosphate minerals are supplemented with spectra of adsorbed P binding forms. First, various soil constituents assumed to be potentially relevant for P sorption were compared with respect to their retention efficiency for orthophosphate and IHP at P levels typical for soils. Then, ...
Source: Journal of Synchrotron Radiation - January 28, 2016 Category: Physics Authors: Prietzel, J.Harrington, G.Häusler, W.Heister, K.Werner, F.Klysubun, W. Tags: LCF linear combination fitting soil phosphorus speciation spectrum deconvolution X-ray absorption near-edge spectroscopy XANES research papers Source Type: research
Local X-ray magnetic circular dichroism study of Fe/Cu(111) using a tunneling smart tip
Localized spectroscopy with simultaneous topographic, elemental and magnetic information is presented. A synchrotron X-ray scanning tunneling microscope has been employed for the local study of the X-ray magnetic circular dichroism at the Fe L2,3-edges of a thin iron film grown on Cu(111). Polarization-dependent X-ray absorption spectra have been obtained through a tunneling smart tip that serves as a photoelectron detector. In contrast to conventional spin-polarized scanning tunneling microscopy, X-ray excitations provide magnetic contrast even with a non-magnetic tip. Intensity variations in the photoexcited tip current ...
Source: Journal of Synchrotron Radiation - January 28, 2016 Category: Physics Authors: DiLullo, A.Shirato, N.Cummings, M.Kersell, H.Chang, H.Rosenmann, D.Miller, D.Freeland, J.W.Hla, S.-W.Rose, V. Tags: synchrotron X-ray scanning tunneling microscopy smart tip XMCD chemical contrast research papers Source Type: research
Image guidance protocol for synchrotron microbeam radiation therapy
The protocol for image-guided microbeam radiotherapy (MRT) developed for the Australian Synchrotron's Imaging and Medical Beamline (IMBL) is described. The protocol has been designed for the small-animal MRT station of IMBL to enable future preclinical trials on rodents. The image guidance procedure allows for low-dose monochromatic imaging at 50 keV and subsequent semi-automated sample alignment in 3D with sub-100 µm accuracy. Following the alignment, a beamline operation mode change is performed and the relevant beamline components are automatically aligned for the treatment (pink) beam to be delivered on the s...
Source: Journal of Synchrotron Radiation - January 28, 2016 Category: Physics Authors: Pelliccia, D.Poole, C.M.Livingstone, J.Stevenson, A.W.Smyth, L.M.L.Rogers, P.A.W.Haüsermann, D.Crosbie, J.C. Tags: microbeam radiotherapy image guidance X-ray imaging X-ray tomography dosimetry research papers Source Type: research
High-speed X-ray imaging pixel array detector for synchrotron bunch isolation
A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8–12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10–100 ps) and in...
Source: Journal of Synchrotron Radiation - January 28, 2016 Category: Physics Authors: Philipp, H.T.Tate, M.W.Purohit, P.Shanks, K.S.Weiss, J.T.Gruner, S.M. Tags: imaging detector high frame rate X-ray detector pixel array detectors time-resolved imaging area detector research papers Source Type: research
Upgrade of beamline BL08B at Taiwan Light Source from a photon-BPM to a double-grating SGM beamline
During the last 20 years, beamline BL08B has been upgraded step by step from a photon beam-position monitor (BPM) to a testing beamline and a single-grating beamline that enables experiments to record X-ray photo-emission spectra (XPS) and X-ray absorption spectra (XAS) for research in solar physics, organic semiconductor materials and spinel oxides, with soft X-ray photon energies in the range 300–1000 eV. Demands for photon energy to extend to the extreme ultraviolet region for applications in nano-fabrication and topological thin films are increasing. The basic spherical-grating monochromator beamline was again ...
Source: Journal of Synchrotron Radiation - August 8, 2015 Category: Physics Authors: Yuh, J.-Y.Lin, S.-W.Huang, L.-J.Fung, H.-S.Lee, L.-L.Chen, Y.-J.Cheng, C.-P.Chin, Y.-Y.Lin, H.-J. Tags: extreme ultraviolet (EUV) soft X-rays spherical-grating monochromator (SGM) beamline Taiwan Light Source photon beam-position monitor (BPM) beamlines Source Type: research
Single-crystal X-ray diffraction and resonant X-ray magnetic scattering at helium-3 temperatures in high magnetic fields at beamline P09 at PETRA III
The resonant scattering and diffraction beamline P09 at PETRA III at DESY is equipped with a 14 T vertical field split-pair magnet. A helium-3 refrigerator is available that can be fitted inside the magnet's variable-temperature insert. Here the results of a series of experiments aimed at determining the beam conditions permitting operations with the He-3 insert are presented. By measuring the tetragonal-to-orthorhombic phase transition occurring at 2.1 K in the Jahn–Teller compound TmVO4, it is found that the photon flux at P09 must be attenuated down to 1.5 × 109 photons s−1 for the sample to re...
Source: Journal of Synchrotron Radiation - August 8, 2015 Category: Physics Authors: Francoual, S.Strempfer, J.Warren, J.Liu, Y.Skaugen, A.Poli, S.Blume, J.Wolff-Fabris, F.Canfield, P.C.Lograsso, T. Tags: X-ray diffraction resonant X-ray magnetic scattering helium-3 insert cryostat sub-Kelvin temperatures X-ray beam heating single-crystal research papers Source Type: research
Optimizing X-ray mirror thermal performance using matched profile cooling
To cover a large photon energy range, the length of an X-ray mirror is often longer than the beam footprint length for much of the applicable energy range. To limit thermal deformation of such a water-cooled X-ray mirror, a technique using side cooling with a cooled length shorter than the beam footprint length is proposed. This cooling length can be optimized by using finite-element analysis. For the Kirkpatrick–Baez (KB) mirrors at LCLS-II, the thermal deformation can be reduced by a factor of up to 30, compared with full-length cooling. Furthermore, a second, alternative technique, based on a similar principle is ...
Source: Journal of Synchrotron Radiation - August 7, 2015 Category: Physics Authors: Zhang, L.Cocco, D.Kelez, N.Morton, D.S.Srinivasan, V.Stefan, P.M. Tags: KB mirror FEL beam thermal deformation variable cooling length adjustable electric heater finite-element modelling water cooling research papers Source Type: research
High-rate dead-time corrections in a general purpose digital pulse processing system
Dead-time losses are well recognized and studied drawbacks in counting and spectroscopic systems. In this work the abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform multi-parameter analysis (arrival time, pulse width, pulse height, pulse shape, etc.) at high input counting rates (ICRs), allowing accurate counting loss corrections even for variable or transient radiations. The fast analysis is used to obta...
Source: Journal of Synchrotron Radiation - August 7, 2015 Category: Physics Authors: Abbene, L.Gerardi, G. Tags: dead-time cascade of dead-times time interval distribution digital pulse processing research papers Source Type: research
A new method for studying sub-pulse dynamics at synchrotron sources
The possibility of studying dynamics at time scales on the order of the pulse duration at synchrotron X-ray sources with present avalanche photodiode point detection technology is investigated, without adopting pump–probe techniques. It is found that sample dynamics can be characterized by counting single and double photon events and an analytical approach is developed to estimate the time required for a statistically significant measurement to be made. The amount of scattering required to make such a measurement possible presently within a few days is indicated and it is shown that at next-generation synchrotron sou...
Source: Journal of Synchrotron Radiation - August 7, 2015 Category: Physics Authors: Wingert, J.Singer, A.Shpyrko, O.G. Tags: coherent X-ray scattering speckle statistics ultrafast dynamics XPCS research papers Source Type: research
Time delay measurement in the frequency domain
Pump–probe studies at synchrotrons using X-ray and laser pulses require accurate determination of the time delay between pulses. This becomes especially important when observing ultrafast responses with lifetimes approaching or even less than the X-ray pulse duration (∼100 ps). The standard approach of inspecting the time response of a detector sensitive to both types of pulses can have limitations due to dissimilar pulse profiles and other experimental factors. Here, a simple alternative is presented, where the frequency response of the detector is monitored versus time delay. Measurements readily demonstrate ...
Source: Journal of Synchrotron Radiation - August 6, 2015 Category: Physics Authors: Durbin, S.M.Liu, S.-C.Dufresne, E.M.Li, Y.Wen, H. Tags: pump – probe X-ray synchrotron ultrafast time resolution RF frequency analysis short communications Source Type: research
Py4Syn: Python for synchrotrons
In this report, Py4Syn, an open-source Python-based library for data acquisition, device manipulation, scan routines and other helper functions, is presented. Driven by easy-to-use and scalability ideals, Py4Syn offers control system agnostic solution and high customization level for scans and data output, covering distinct techniques and facilities. Here, most of the library functionalities are described, examples of use are shown and ideas for future implementations are presented. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - August 6, 2015 Category: Physics Authors: Slepicka, H.H.Canova, H.F.Beniz, D.B.Piton, J.R. Tags: Python Py4Syn data acquisition devices research papers Source Type: research
SIMPLEX: simulator and postprocessor for free-electron laser experiments
SIMPLEX is a computer program developed for simulating the amplification process of free-electron lasers (FELs). It numerically solves the so-called FEL equations describing the evolution of the radiation field and growth of microbunching while the electron beam travels along the undulator. In order to reduce the numerical cost, the FEL equations have been reduced to more convenient forms for numerical implementation by applying reasonable approximations. SIMPLEX is equipped with a postprocessor to facilitate the retrieval of desired information from the simulation results, which is crucial for practical applications such ...
Source: Journal of Synchrotron Radiation - August 5, 2015 Category: Physics Authors: Tanaka, T. Tags: free-electron laser simulation computer programs Source Type: research
On the ANKA decision: a response to Braun's Just for us?
KIT's Executive Board has decided to discontinue the operation of the synchrotron radiation facility ANKA within category LK-II (user facility) of the Helmholtz Association and continue operation in LK-I (research). The KIT Senate confirmed this decision. Some aspects of the background and the rationale leading to this change are explained. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - August 4, 2015 Category: Physics Authors: Saile, V. Tags: ANKA KIT user facility letters to the editor Source Type: research
Just for us?
It is a regrettable decision by Karlsruhe Institute of Technology that ANKA, the Angströmquelle Karlsruhe, is terminating its external synchrotron user support program. ANKA has an excellent performance review grading sheet and has been a valuable source and resource to international users for over a decade. There is concern among users that ANKA's decision could become an example for other synchrotrons as well. (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - August 4, 2015 Category: Physics Authors: Braun, A. Tags: Angstr ö mquelle Karlsruhe ANKA technology-based research synchrotron facility user program letters to the editor Source Type: research
A sub-micrometer resolution hard X-ray microprobe system of BL8C at Pohang Light Source
A microprobe system has been installed on the nanoprobe/XAFS beamline (BL8C) at PLS-II, South Korea. Owing to the reproducible switch of the gap of the in-vacuum undulator (IVU), the intense and brilliant hard X-ray beam of an IVU can be used in X-ray fluorescence (XRF) and X-ray absorption fine-structure (XAFS) experiments. For high-spatial-resolution microprobe experiments a Kirkpatrick–Baez mirror system has been used to focus the millimeter-sized X-ray beam to a micrometer-sized beam. The performance of this system was examined by a combination of micro-XRF imaging and micro-XAFS of a beetle wing. These results i...
Source: Journal of Synchrotron Radiation - August 4, 2015 Category: Physics Authors: Sung, N.-E.Lee, I.-J.Lee, K.-S.Jeong, S.-H.Kang, S.-W.Shin, Y.-B. Tags: X-ray instrumentation microprobe XAFS micro-XRF micro-XANES beamlines Source Type: research
Muffin-tin potentials in EXAFS analysis
Muffin-tin potentials are the standard tool for calculating the potential surface of a cluster of atoms for use in the analysis of extended X-ray absorption fine-structure (EXAFS) data. The set of Cartesian coordinates used to define the positions of atoms in the cluster and to calculate the muffin-tin potentials is commonly also used to enumerate the scattering paths used in the EXAFS data analysis. In this paper, it is shown that these muffin-tin potentials are sufficiently robust to be used to examine quantitatively contributions to the EXAFS data from scattering geometries not represented in the original cluster. (Sour...
Source: Journal of Synchrotron Radiation - July 25, 2015 Category: Physics Authors: Ravel, B. Tags: EXAFS real-space multiple scattering data analysis muffin-tin potential research papers Source Type: research
On EXAFS Debye-Waller factor and recent advances
The effects of structural and vibrational disorder on the EXAFS signals are parameterized in terms of the Debye Waller (DW) factor. Here the vibrational contribution is addressed, which for most systems can be singled out by studying the temperature dependence of the EXAFS DW factor, which corresponds to a good accuracy to the parallel mean square relative displacement (MSRD) around the inter-atomic equilibrium distance. By comparing the first-shell EXAFS thermal expansion with the crystallographic thermal expansion one can evaluate the perpendicular MSRD. The results of recent measurements on copper and on several tetrahe...
Source: Journal of Synchrotron Radiation - July 22, 2015 Category: Physics Authors: Fornasini, P.Grisenti, R. Tags: EXAFS thermal disorder Debye-Waller factor Einstein model Debye model research papers Source Type: research
Optimized IR synchrotron beamline design
Synchrotron infrared beamlines are powerful tools on which to perform spectroscopy on microscopic length scales but require working with large bending-magnet source apertures in order to provide intense photon beams to the experiments. Many infrared beamlines use a single toroidal-shaped mirror to focus the source emission which generates, for large apertures, beams with significant geometrical aberrations resulting from the shape of the source and the beamline optics. In this paper, an optical layout optimized for synchrotron infrared beamlines, that removes almost totally the geometrical aberrations of the source, is pre...
Source: Journal of Synchrotron Radiation - July 22, 2015 Category: Physics Authors: Moreno, T. Tags: infrared synchrotron beamline bending magnet optical aberrations optical path research papers Source Type: research
A plug-and-measure diagnostic tool for flux, resolution and beam size of a soft X-ray beamline
A compact multi-functional diagnostic tool has been installed for commissioning beamlines at the Taiwan Light Source. For a photon beam, the instrument can measure the photon flux, energy resolution and beam size, consecutively with a photodiode or gold mesh, a windowless gas cell and a movable fluorescence screen viewport. Two gratings with ruling densities of 350 and 1000 lines mm−1 and dispersing photons of energies from 80 to 1200 eV were calibrated with a photon flux of 1011 photon s−1 at slit openings of 50 µm × 50 µm; a maximum resolving power of greater than 10000 was certi...
Source: Journal of Synchrotron Radiation - July 21, 2015 Category: Physics Authors: Wei, C.-H.Lin, H.-C.Lin, S.-W.Yuh, J.-Y. Tags: windowless ion chamber soft X-ray beamline gas phase absorption dynamic beam size monitor short communications Source Type: research
Investigating structural aspects to understand the putative/claimed non-toxicity of the Hg-based Ayurvedic drug Rasasindura using XAFS
XANES- and EXAFS-based analysis of the Ayurvedic Hg-based nano-drug Rasasindura has been performed to seek evidence of its non-toxicity. Rasasindura is determined to be composed of single-phase α-HgS nanoparticles (size ∼24 nm), free of Hg0 or organic molecules; its structure is determined to be robust ( (Source: Journal of Synchrotron Radiation)
Source: Journal of Synchrotron Radiation - July 21, 2015 Category: Physics Authors: Ramanan, N.Lahiri, D.Rajput, P.Varma, R.C.Arun, A.Muraleedharan, T.S.Pandey, K.K.Maiti, N.Jha, S.N.Sharma, S.M. Tags: Ayurvedic drug XAFS Hg toxicity research papers Source Type: research