Publications (4)6.66 Total impact
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Article: Asynchronous sampling for ultrafast experiments with low momentum compaction at the ANKA ring.
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ABSTRACT: A high-repetition-rate pump-probe experiment is presented, based on the asynchronous sampling approach. The low-α mode at the synchrotron ANKA can be used for a time resolution down to the picosecond limit for the time-domain sampling of the coherent THz emission as well as for hard X-ray pump-probe experiments, which probe structural dynamics in the condensed phase. It is shown that a synchronization of better than 1 ps is achieved, and examples of phonon dynamics of semiconductors are presented.Journal of Synchrotron Radiation 07/2011; 18(Pt 4):539-45. · 2.73 Impact Factor -
Article: Assessment of chemical species of lead accumulated in tidemarks of human articular cartilage by X-ray absorption near-edge structure analysis.
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ABSTRACT: A highly specific accumulation of the toxic element lead was recently measured in the transition zone between non-calcified and calcified normal human articular cartilage. This transition zone, the so-called `tidemark', is considered to be an active calcification front of great clinical importance. However, little is known about the mechanisms of accumulation and the chemical form of Pb in calcified cartilage and bone. Using spatially resolved X-ray absorption near-edge structure analysis (µ-XANES) at the Pb L(3)-edge, the chemical state of Pb in the osteochondral region was investigated. The feasibility of the µ-XANES set-up at the SUL-X beamline (ANKA synchrotron light source) was tested and confirmed by comparing XANES spectra of bulk Pb-reference compounds recorded at both the XAS and the SUL-X beamline at ANKA. The µ-XANES set-up was then used to investigate the tidemark region of human bone (two patella samples and one femoral head sample). The spectra recorded at the tidemark and at the trabecular bone were found to be highly correlated with the spectra of synthetic Pb-doped carbonated hydroxyapatite, suggesting that in both of these very different tissues Pb is incorporated into the hydroxyapatite structure.Journal of Synchrotron Radiation 03/2011; 18(Pt 2):238-44. · 2.73 Impact Factor -
Article: An Efficient Referencing And Sample Positioning System To Investigate Heterogeneous Substances With Combined Microfocused Synchrotron X-ray Techniques
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ABSTRACT: A referencing and sample positioning system has been developed to transfer object positions measured with an offline microscope to a synchrotron experimental station. The accuracy should be sufficient to deal with heterogeneous samples on micrometer scale. Together with an online fluorescence mapping visualisation the optical alignment helps to optimize measuring procedures for combined microfocused X-ray techniques.AIP Conference Proceedings 01/2009; 1092(1). -
Article: Simulation of X-ray beamlines with the new ray tracing tool XTrace
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ABSTRACT: A novel X-ray tracing simulation tool XTrace has been developed recently in order to calculate the beam properties from the X-ray source (bending magnet, undulator, wiggler, etc.) through all optical elements (slit, filter, window, mirror, crystal monochromator, multilayer, etc.) and the sample to the detector. In XTrace, the diffraction by a perfect crystal is described by the dynamical theory taking into account refraction and absorption effects. The code has been used to simulate the X-ray beamline of the Synchrotron Laboratory for Environmental Studies (Synchrotron Umwelt-Labor (SUL)) at ANKA. XTrace has been successfully used to simulate precisely the beam parameters such as position, size, divergence, photon flux, transmission, heat load, etc. at any distance from the source. For a better insight it is also possible to visualize the beam profile, energy spectrum, transmission spectrum, intensity distribution, power density, heat load, foot print, DuMond diagram, ray propagation diagram, etc. An excellent agreement between measured and simulated flux intensities over the whole energy range at the sample position for the X-ray beamline SUL has been found. XTrace has been proven to be a reliable, powerful, fast and easy to use tool for describing existing and designing and optimizing new X-ray beamlines in the future.Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 582(1):90-92. · 1.21 Impact Factor
