Zakharova M., Vlnieska V., Fornasier H., Borner M., dos Santos Rolo T., Mohr J., Kunka D.

in Applied Sciences (Switzerland), 8 (2018), 468. DOI:10.3390/app8030468

Abstract

© 2018 by the authors. Single-shot grating-based phase-contrast imaging techniques offer additional contrast modalities based on the refraction and scattering of X-rays in a robust and versatile configuration. The utilization of a single optical element is possible in such methods, allowing the shortening of the acquisition time and increasing flux efficiency. One of the ways to upgrade single-shot imaging techniques is to utilize customized optical components, such as two-dimensional (2D) X-ray gratings. In this contribution, we present the achievements in the development of 2D gratings with UV lithography and gold electroplating. Absorption gratings represented by periodic free-standing gold pillars with lateral structure sizes from 5 μm to 25 μm and heights from 5 μm to 28 μm have shown a high degree of periodicity and defect-free patterns. Grating performance was tested in a radiographic setup using a self-developed quality assessment algorithm based on the intensity distribution histograms. The algorithm allows the final user to estimate the suitability of a specific grating to be used in a particular setup.

Rota L., Caselle M., Brundermann E., Funkner S., Gerth C., Kehrer B., Mielczarek A., Makowski D., Mozzanica A., Muller A.-S., Nasse M.J., Niehues G., Patil M., Schmitt B., Schonfeldt P., Steffen B., Weber M.

in Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment (2018). DOI:10.1016/j.nima.2018.10.093

Abstract

© 2018 Synchrotrons and modern FEL light sources operate with bunch repetition rates in the MHz range. The profile of the electron beam inside the accelerator can be characterized with indirect experimental techniques where linear array detectors are employed to measure the emitted synchrotron radiation or the spectrum of a near-IR laser. To improve the performance of modern beam diagnostics we have developed KALYPSO, a detector system operating with a continuous frame rate of up to 2.7 MHz. To facilitate the integration in different experiments, a modular architecture has been adopted. Different semiconductor micro-strip sensors can be connected to front-end ASICs to optimize the quantum efficiency at different photon energies, ranging from visible light up to near-IR. The front-end electronics are integrated within an heterogeneous DAQ consisting of FPGAs and GPUs, which allows scientists to implement real-time data processing algorithms. The current version of the detector is in operation at the KARA synchrotron light source and at the European XFEL. In this contribution we present the detector architecture, the performance results and the on-going technical developments.

Asadchikov V., Buzmakov A., Chukhovskii F., Dyachkova I., Zolotov D., Danilewsky A., Baumbach T., Bode S., Haaga S., Hanschke D., Kabukcuoglu M., Balzer M., Caselle M., Suvorov E.

in Journal of Applied Crystallography (2018). DOI:10.1107/S160057671801419X

Abstract

© International Union of Crystallography, 2018 This article describes complete characterization of the polygonal dislocation half-loops (PDHLs) introduced by scratching and subsequent bending of an Si(111) crystal. The study is based on the X-ray topo-tomography technique using both a conventional laboratory setup and the high-resolution X-ray image-detecting systems at the synchrotron facilities at KIT (Germany) and ESRF (France). Numerical analysis of PDHL images is performed using the Takagi–Taupin equations and the simultaneous algebraic reconstruction technique (SART) tomographic algorithm.

Miko I., van de Kamp T., Trietsch C., Ulmer J.M., Zuber M., Baumbach T., Deans A.R.

in PeerJ, 2018 (2018), e5174. DOI:10.7717/peerj.5174

Abstract

© 2018 Mikó et al. Ceraphronoids are some of the most commonly collected hymenopterans, yet they remain rare in the fossil record. Conostigmus talamasi Mikó and Trietsch, sp. nov. from Baltic amber represents an intermediate form between the type genus, Megaspilus, and one of the most species-rich megaspilid genera, Conostigmus. We describe the new species using 3D data collected with synchrotron-based micro-CT equipment. This non-invasive technique allows for quick data collection in unusually high resolution, revealing morphological traits that are otherwise obscured by the amber. In describing this new species, we revise the diagnostic characters for Ceraphronoidea and discuss possible reasons why minute wasps with a pterostigma are often misidentified as ceraphronoids. Based on the lack of ceraphronoid characteristics, we remove Dendrocerus dubitatus Brues, 1937, Stigmaphronidae, and Radiophronidae from Ceraphronoidea and consider them as incertae sedis. We also provide some guidance for their future classification.

Sakraker Ozmen I., Joshi A., Bohrk H., Hanschke D., Cecilia A.

in 2018 Joint Thermophysics and Heat Transfer Conference (2018), AIAA 2018-3588. DOI:10.2514/6.2018-3588

Abstract

© 2018 by Isil Sakraker Özmen, Archana Joshi, Hannah Boehrk, Daniel Haenschke, Angelica Cecilia. Published by the American Institute of Aeronautics and Astronautics, Inc. The cork based DLR Cork and low density DLR ZURAM materials were exposed to heat while being monitored by x-ray radiation in a synchrotron facility. A portable furnace was manufactured to provide the low pressure conditions of the atmospheric entry and the high stagnation heat fluxes. A total of 4 samples were exposed to radiative heating at 10.4 mbar pressure. The sample was rotated inside the furnace by a miniature servomotor to allow for 3D image reconstruction. Furthermore, 2D radiography sequences were also acquired with stationary samples. The charring, char front propagation and volumetric expansion were prominent in the case of DLR Cork. Even though the ZURAM sample did not significantly char, volumetric phenomena were observed even in the virgin regions. 3D image sequences are provided for ablating DLR Cork material, where the surface topology evolution can be observed. Furthermore, individual cork granules could be tracked throughout the ablation. An optical flow analysis was applied to track the carbon fibers following the volumetric phenomena inside the DLR ZURAM samples.

Ametova E., Ferrucci M., Chilingaryan S., Dewulf W.

in Precision Engineering (2018). DOI:10.1016/j.precisioneng.2018.05.016

Abstract

© 2018 Elsevier Inc. X-ray computed tomography (CT) is an imaging technique that allows the reconstruction of an imaged part in the form of a three-dimensional attenuation map. The CT data acquisition process consists of acquiring X-ray transmission images from multiple perspectives. Analysis of the reconstructed attenuation map can provide dimensional and material information about the measured part(s). Therefore, CT is recognized as a solution for quality control tasks, for example dimensional inspection of complex objects with intricate inner geometries. CT measurements can suffer from various sources of error in the measurement procedure. One such influence is the geometrical alignment of the CT instrument components. Typical tomographic reconstruction algorithms impose strict requirements on the relative position and orientation of the three main components: X-ray source, rotation axis of the sample stage, and X-ray detector. Any discrepancy in the actual CT geometry from the geometry assumed by the reconstruction algorithm will contribute to errors in measurements performed on the reconstructed data. There is currently no standardized or easily implementable method for users to compensate geometrical misalignments of the CT instrument. In many cases, the procedure of mechanical adjustment of CT instrument is time consuming and impractical. In this paper, we show that software-based compensation of deviations in CT instrument geometry is an effective alternative to mechanical adjustment of CT instrument. Through computer simulations, we compare qualitatively and quantitatively two methods to compensate CT instrument misalignment: radiographic re-binning (interpolation) and a modified conventional reconstruction algorithm with embedded misalignment compensation.

Jerome N.T., Kopmann A.

in VISIGRAPP 2018 – Proceedings of the 13th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications, 3 (2018) 341-348.

Abstract

© 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved. With the advancement of instrument precision, research facilities are generating data at an unprecedented rate. These experimental results are stored in a digital library platform which the contents are later accessible from within the facility or the public. However, the sheer volume of collected data is overwhelming the capacity of researchers and impedes the process of browsing for the desired data. In this paper, we present a concept of Digital Visual Exploration Library (DVEL) based on the confluence of two major research domains-digital library and visualisation-that enables efficient browsing of the growing data within a digital library. We complement the current state-of-the-art textual metadata description by integrating visual exploration to address big complex data, i.e., data of large size, multimodal data and multivariate data. We describe our concept based on use cases from three unique domains: climate research with Doppler wind lidar, X-ray-imaging for entomology research, and medical imaging with ultrasound computer tomography.

Reich S., Gottlicher J., Letzel A., Gokce B., Barcikowski S., dos Santos Rolo T., Baumbach T., Plech A.

in Applied Physics A: Materials Science and Processing, 124 (2018), 71. DOI:10.1007/s00339-017-1503-3

Abstract

© 2017, Springer-Verlag GmbH Germany, part of Springer Nature. Pulsed laser ablation in liquids (PLAL) as an attractive process for ligand-free nanoparticle synthesis represents a multiscale problem to understand the mechanisms and achieve control. Atomic and nanoscale processes interacting with macroscale dynamics in the liquid demand for sensitive tools for in-situ and structural analysis. By adding X-ray methods, we enlarge the available information on millimeter-scale bubble formation down to atomic-scale nanoparticle reactions. X-ray spectroscopy (XAS) can resolve the chemical speciation of the ablated material during the ablation from a zinc wire target showing a first oxidation step from zinc to zinc oxide within some 10 min followed by a slower reaction to hydrozincite. X-ray imaging investigations also give additional information on the bubble dynamics as we demonstrate by comparing the microsecond radiography and optical stroboscopy. We show different features of the detachment of the ablation bubble from a free wire. The location of the first collapse occurs in front of the target. While a first rebound bubble possesses an homogeneous interior, the subsequent rebound consists merely of a cloud of microbubbles.

Aggleton R. et al.

in Journal of Instrumentation, 12 (2017), P12019. DOI:10.1088/1748-0221/12/12/P12019

Abstract

© 2017 CERN. A new tracking detector is under development for use by the CMS experiment at the High-Luminosity LHC (HL-LHC). A crucial requirement of this upgrade is to provide the ability to reconstruct all charged particle tracks with transverse momentum above 2-3 GeV within 4 μs so they can be used in the Level-1 trigger decision. A concept for an FPGA-based track finder using a fully time-multiplexed architecture is presented, where track candidates are reconstructed using a projective binning algorithm based on the Hough Transform, followed by a combinatorial Kalman Filter. A hardware demonstrator using MP7 processing boards has been assembled to prove the entire system functionality, from the output of the tracker readout boards to the reconstruction of tracks with fitted helix parameters. It successfully operates on one eighth of the tracker solid angle acceptance at a time, processing events taken at 40 MHz, each with up to an average of 200 superimposed proton-proton interactions, whilst satisfying the latency requirement. The demonstrated track-reconstruction system, the chosen architecture, the achievements to date and future options for such a system will be discussed.

Stevanovic, Uros

PhD thesis, Faculty of Electrical Engineering and Information Technology, Karlsruhe Institute of Technology, 2017.

Abstract

This dissertation proposes a novel smart camera platform serving as a flexible data acquisition system for scientific applications. Current technological progress offers increasing performance in the areas we consider, namely high data-throughput, data processing, and detector performance. Prevalent data acquisition solutions typically focus on one of these aspects. However, driven by science, experiments experience increasing demands in terms of data throughput, speed and flexibility. In this dissertation, we introduce a system which, in addition to being able to provide high-speed data transfer, is also capable of interpreting the incoming information at an early stage. In order to demonstrate the full potential of the smart camera platform, we focus on X-ray imaging with synchrotron light sources. X-ray imaging applications can investigate the traits of technological and biological processes over microseconds for radiography, and milliseconds for tomography applications. These applications may require different sensors, and include complex experiment operations. The new smart camera platform is part of a larger project, UFO, which introduces a new concept for X-ray imaging. On-line data assessment is used to provide a data-driven feedback and active management of both the process and data acquisition procedure. This is accomplished using a GPU platform for fast reconstruction, embedded on-camera data processing, and integrating smart camera in a high-throughput data acquisition system. The final design of the smart camera platform consists of a custom high-performance FPGA board, providing continuous data transfer, embedded image processing, and a flexible input stage. In the IMAGE beamline of ANKA, camera is integrated in the new control system, and used in real-life applications. A maximum data-throughput of up to 8 GB/s is achieved. A custom image-based algorithm is implemented in the FPGA, with stringent real-time requirements, able to increase native sensor speed up to five times while reducing the amount of transfered data. Several image sensors are used, with resolutions of up to 20 megapixels and frame rates of up to 5 kfps. The smart camera platform was also used in non-imaging applications, stemming from the flexible input stage. The proposed camera architecture enables the user to modify the current system for any kind of high data-throughput applications, and to modify and implement custom processing algorithms.

 

First assessor: Prof. Dr. M. Weber
Second assessor: Prof. Dr.-Ing. Dr. h.c. J. Becker