Niehues G., Brosi M., Briindermann E., Casclle M., Funkncr S., Kehrer B., Nasse M.J., Patil M., Rota L., Steinmann J.L., Weber M., Muller A.-S.

in International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz, 2018-September (2018), 8510133. DOI:10.1109/IRMMW-THz.2018.8510133


© 2018 IEEE. A key bottleneck for investigations of ultrafast processes is a detection scheme to record all individual spectra with high repetition rates to avoid averaging and to improve the signal-to-noise ratio. Here, we present spectral measurements of fs laser sources used for electro-optical detection with a KIT-developed linear sensor array and DAQ system adapted to light sources with MHz repetition rates. This system can be equipped with different sensor types covering a broad wavelength range. It can therefore be used for various applications and scientific questions. The presented exemplary applications range from accelerator-based diagnostics to table-top laser experiments.

Funkner S., Brosi M., Briindcrmantr E., Caselle M., Nasse M.J., Niehues G., Rota L., Schonfeldr P., Weber M., Muller A.-S.

in International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz, 2018-September (2018), 8510080. DOI:10.1109/IRMMW-THz.2018.8510080


© 2018 IEEE. At the KArlsruhe Research Accelerator (KARA), we use electro-optical sampling to measures profiles of compressed electron bunches during the microbunching instability. The observation of the complex dynamics of this instability is of special interest because it leads to intense THz radiation bursts. As the revolution frequency of the storage ring is 2.72 MHz, high detection rates are required to record the bunch profiles for every revolution with single-shot measurements. To achieve fast detection rates, we implemented a KIT-developed ultra-fast line array and recorded the electron bunch charge density for every revolution for 3.6 s with a data throughput of 1.4 GBytes/s.

Kehrer B., Brosi M., Steinmann J.L., Blomley E., Brundermann E., Caselle M., Funkner S., Hiller N., Nasse M.J., Niehues G., Rota L., Schedler M., Schonfeldt P., Schuh M., Schutze P., Weber M., Muller A.-S.

in Physical Review Accelerators and Beams, 21 (2018), 102803. DOI:10.1103/PhysRevAccelBeams.21.102803


© 2018 authors. Published by the American Physical Society. To understand and control dynamics in the longitudinal phase space, time-resolved measurements of different bunch parameters are required. For a reconstruction of this phase space, the detector systems have to be synchronized. This reconstruction can be used for example for studies of the microbunching instability which occurs if the interaction of the bunch with its own radiation leads to the formation of substructures on the longitudinal bunch profile. These substructures can grow rapidly – leading to a sawtooth-like behavior of the bunch. At KARA, we use a fast-gated intensified camera for energy spread studies, Schottky diodes for coherent synchrotron radiation studies as well as electro-optical spectral decoding for longitudinal bunch profile measurements. For a synchronization, a synchronization scheme is used which compensates for hardware delays. In this paper, the different experimental setups and their synchronization are discussed and first results of synchronous measurements presented.

Evangelista Y. et al.

in Journal of Instrumentation, 13 (2018), P09011. DOI:10.1088/1748-0221/13/09/P09011


© 2018 IOP Publishing Ltd and Sissa Medialab. Multi-pixel fast silicon detectors represent the enabling technology for the next generation of space-borne experiments devoted to high-resolution spectral-timing studies of low-flux compact cosmic sources. Several imaging detectors based on frame-integration have been developed as focal plane devices for X-ray space-borne missions but, when coupled to large-area concentrator X-ray optics, these detectors are affected by strong pile-up and dead-time effects, thus limiting the time and energy resolution as well as the overall system sensitivity. The current technological gap in the capability to realize pixelated silicon detectors for soft X-rays with fast, photon-by-photon response and nearly Fano-limited energy resolution therefore translates into the unavailability of sparse read-out sensors suitable for high throughput X-ray astronomy applications. In the framework of the ReDSoX Italian collaboration, we developed a new, sparse read-out, pixelated silicon drift detector which operates in the energy range 0.5-15 keV with nearly Fano-limited energy resolution (≤150 eV FWHM @ 6 keV) at room temperature or with moderate cooling (∼0°C to +20°C). In this paper, we present the design and the laboratory characterization of the first 16-pixel (4 × 4) drift detector prototype (PixDD), read-out by individual ultra low-noise charge sensitive preamplifiers (SIRIO) and we discuss the future PixDD prototype developments.

Blank T., Pfistner P., Leyrer B., Caselle M., Simons C., Schmidt C.J., Weber M.

in 2018 International Conference on Electronics Packaging and iMAPS All Asia Conference, ICEP-IAAC 2018 (2018) 288-292. DOI:10.23919/ICEP.2018.8374306


© 2018 Japan Institute of Electronics Packaging. The Compressed Baryonic Matter Experiment (CBM) investigates highly compressed nuclear matter, utilizing a Silicon Tracking System comprising 896 silicon sensors modules packed in eight layers with an overall area of four sqm. Each module consists of one sensor, 16 Read-Out Chips and 16 double-layer micro flex-cables, which are connected to the top and bottom side of the sensor. The cables are up to 50 cm long. They carry 128 signal traces on two layers at a pitch of 100 μm and a line-width of 25 μm. The layers are separated by a meshed core to reduce the cable capacity to 0.44 pF/cm. The cables are bonded onto one sensor by a pick and place flip-chip machine. The interconnection is realized by gold stud-bumps on the silicon and SAC solder bumps on the cable. The status of the sensor module and cable production process are presented.

Rolo T.S., Reich S., Karpov D., Gasilov S., Kunka D., Fohtung E., Baumbach T., Plech A.

in Applied Sciences (Switzerland), 8 (2018), 737. DOI:10.3390/app8050737


© 2018 by the authors. An array of compound refractive X-ray lenses (CRL) with 20 × 20 lenslets, a focal distance of 20 cm and a visibility of 0.93 is presented. It can be used as a Shack-Hartmann sensor for hard X-rays (SHARX) for wavefront sensing and permits for true single-shot multi-contrast imaging the dynamics of materials with a spatial resolution in the micrometer range, sensitivity on nanosized structures and temporal resolution on the microsecond scale. The object’s absorption and its induced wavefront shift can be assessed simultaneously together with information from diffraction channels. In contrast to the established Hartmann sensors the SHARX has an increased flux efficiency through focusing of the beam rather than blocking parts of it. We investigated the spatiotemporal behavior of a cavitation bubble induced by laser pulses. Furthermore, we validated the SHARX by measuring refraction angles of a single diamond CRL, where we obtained an angular resolution better than 4 μrad.

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

in Measurement Science and Technology, 29 (2018), 065007. DOI:10.1088/1361-6501/aab1a1


© 2018 IOP Publishing Ltd. The recent emergence of advanced manufacturing techniques such as additive manufacturing and an increased demand on the integrity of components have motivated research on the application of x-ray computed tomography (CT) for dimensional quality control. While CT has shown significant empirical potential for this purpose, there is a need for metrological research to accelerate the acceptance of CT as a measuring instrument. The accuracy in CT-based measurements is vulnerable to the instrument geometrical configuration during data acquisition, namely the relative position and orientation of x-ray source, rotation stage, and detector. Consistency between the actual instrument geometry and the corresponding parameters used in the reconstruction algorithm is critical. Currently available procedures provide users with only estimates of geometrical parameters. Quantification and propagation of uncertainty in the measured geometrical parameters must be considered to provide a complete uncertainty analysis and to establish confidence intervals for CT dimensional measurements. In this paper, we propose a computationally inexpensive model to approximate the influence of errors in CT geometrical parameters on dimensional measurement results. We use surface points extracted from a computer-aided design (CAD) model to model discrepancies in the radiographic image coordinates assigned to the projected edges between an aligned system and a system with misalignments. The efficacy of the proposed method was confirmed on simulated and experimental data in the presence of various geometrical uncertainty contributors.

Reich S., Dos Santos Rolo T., Letzel A., Baumbach T., Plech A.

in Applied Physics Letters, 112 (2018), 151903. DOI:10.1063/1.5022748


© 2018 Author(s). We demonstrate the fabrication of a 2D Compound Array Refractive Lens (CARL) for multi-contrast X-ray imaging. The CARL consists of six stacked polyimide foils with each displaying a 2D array of lenses with a 65 μm pitch aiming for a sensitivity on sub-micrometer structures with a (few-)micrometer resolution in sensing through phase and scattering contrast at multiple keV. The parabolic lenses are formed by indents in the foils by a paraboloid needle. The ability for fast single-exposure multi-contrast imaging is demonstrated by filming the kinetics of pulsed laser ablation in liquid. The three contrast channels, absorption, differential phase, and scattering, are imaged with a time resolution of 25 μs. By changing the sample-detector distance, it is possible to distinguish between nanoparticles and microbubbles.

Cavadini P., Weinhold H., Tonsmann M., Chilingaryan S., Kopmann A., Lewkowicz A., Miao C., Scharfer P., Schabel W.

in Experiments in Fluids, 59 (2018), 61. DOI:10.1007/s00348-017-2482-z


© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. To understand the effects of inhomogeneous drying on the quality of polymer coatings, an experimental setup to resolve the occurring flow field throughout the drying film has been developed. Deconvolution microscopy is used to analyze the flow field in 3D and time. Since the dimension of the spatial component in the direction of the line-of-sight is limited compared to the lateral components, a multi-focal approach is used. Here, the beam of light is equally distributed on up to five cameras using cubic beam splitters. Adding a meniscus lens between each pair of camera and beam splitter and setting different distances between each camera and its meniscus lens creates multi-focality and allows one to increase the depth of the observed volume. Resolving the spatial component in the line-of-sight direction is based on analyzing the point spread function. The analysis of the PSF is computational expensive and introduces a high complexity compared to traditional particle image velocimetry approaches. A new algorithm tailored to the parallel computing architecture of recent graphics processing units has been developed. The algorithm is able to process typical images in less than a second and has further potential to realize online analysis in the future. As a prove of principle, the flow fields occurring in thin polymer solutions drying at ambient conditions and at boundary conditions that force inhomogeneous drying are presented.

A N Danilewski, J Becker, T Baumbach, D Hänschke, A Kopmann, V Asadchikov, M Kovalchuk

Final report, BMBF Programme: “Development and Use of Accelerator-Based Photon Sources (2014)”

Project duration: 01.10.2014 – 30.09.2017

Executive summary

Within the STROBOS-CODE project, partners from two German (KIT, University Freiburg (UFREI)) and two Russian (Shubnikov Institute of Crystallography (SHUB), Kurchatov Institute (KUR)) institutions developed and optimized a novel methodology for correlative 2D, 3D, and 4D characterization of crystalline materials, based on X-ray diffraction imaging. In short, the joint work comprised the theoretical description of the measurement principles, the derivation of the measurement procedures, the specification, design, and construction of the corresponding instrumentation, the formulation and implementation of the data analysis algorithms, as well as the experimental demonstration of the methodology.

The driving application within the project is the in situ investigation of crystals and devices, aiming for a fundamental understanding of structure, nucleation, arrangement, propagation, and extension of defects like dislocations or cracks. In this context, the results of the STROBOS-CODE project will open new perspectives to improve prediction, control, and avoidance of critical defects during the industrial growth and processing of technologically relevant crystals, in particular semi-conductor wafers e.g. for microelectronic devices or solar cells. For several selected use cases, the methodology developed within the STROBOS-CODE project has already been demonstrated, successfully.

The core element of the methodical development is X-ray imaging based on Bragg diffraction contrast, which is highly sensitive to local elastic and plastic deformation of crystal lattices as typically associated with crystal defects. Based on the results of the preceding UFO project and on the prior development of the basic 3D X-ray diffraction laminography (XDL), within STROBOS-CODE an advanced methodology has been made available for correlative characterization and with in situ capabilities. The correlative analysis of data obtained by complementary techniques like X-ray white-beam topography or visible light microscopy now allows creating an unprecedented comprehensive picture of crystalline defects like dislocation networks.
The adaption and optimization of laminographic 3D reconstruction algorithms to the specific requirements of X-ray Bragg diffraction contrast imaging has been performed. Aiming for in situ ca-pabilities, particular interest was put on the reduction of the number of projections required for XDL reconstruction, which could be successfully reduced from about 700 to 50-100 by the appropriate utilization of DART-based algorithms. This progress in data processing resulted in a substantial reduction of the measurement time, for the first time enabling quasi in situ characterization of dislocation dynamics with 3D XDL scans interleaved with a step-wise thermal treatment of the investigated samples.

A concept for a mobile instrument suited for general purpose full-field X-ray diffraction imaging, referred to as the CODE station, has been worked out. A first prototype was successfully realized, served as a test instrument, and enabled first experiments. The results were used to further improve the methodology. Despite the constraints due to the compact and lightweight design, an angular precision and stability of all critical elements better than 1.5e-4 degree was successfully demonstrated. The components of the final instrumentation have been specified and ordered and the final assembly will be performed by UFREI during its extended project run-time until 2019. Afterwards, the highly flexible and mobile CODE-instrumentation will be available for routine experiments at all suitable synchrotron end stations, like e.g. at PETRA III or at the ESRF.

For the STROBOS-instrumentation in Moscow a modular camera system has been developed, constructed, implemented, and tested in cooperation with the Russian partners. It is designed to enable a continuous data streaming with up to 5GB/s. Depending on the application case, differ-ent image sensors can be installed: Sensors with 2, 4, and 20 megapixel are presently available, with a read-out speed of up to 330 frames/s. A sub-zero cooling system has been developed and the camera has been mechanically and electrically integrated for use within the STROBOS set-up.

Within the STROBOS-CODE project, several experiments demonstrated successfully the unique capabilities of the proposed concept for the instrumentation as well as of the developed methodology for correlative and quasi in situ characterization of crystal defects in technologically relevant samples like semiconductor wafers. An unprecedented, comprehensive picture of the onset of thermally driven plastic deformation of silicon wafers could be obtained and provided novel insight into the involved mechanisms. Moreover, for the first time the dynamics of dislocation nucleation and evolution could be monitored in 3D by interleaving XDL measurements and controlled step-wise annealing. Finally, also the applicability of the developed diffraction imaging methodology to higher absorbing materials could be demonstrated by the 3D visualization of dislocation cell structures in a GaAs wafer.
The results of the STROBOS-CODE project have been reported at several national and international workshops and conferences and in more than 10 peer-reviewed publications. In close collaboration, the German and Russian partners have advanced the development on the field of photon science and the methodological progress for large-scale facilities. The methodology and instrumentation developed (improve the research infrastructure at the Kurchatov Institute (STROBOS) and at KIT and other synchrotron infrastructures (CODE). The consortium created for the STROBOS-CODE project will exists beyond the project duration and will extend the cooperation and partnership of Russian and German institutions, in particular on the field of X-ray analytics, algorithms, image processing, and the characterization of crystalline materials and components. In Germany, STROBOS-CODE supports the research partnership of KIT and UFREI within the joint virtual institute “BIRD” and intensifies and strengthens their close collaboration on the field of materials science and microsystem technology.