Alaribe L., Disch C., Fauler A., Engels R., Keller E., Cecilia A., Dos Santos Rolo T., Hamann E., Fiederle M.

in IEEE Transactions on Nuclear Science, 59 (2012) 2193-2195, 6303848. DOI:10.1109/TNS.2012.2212208

Abstract

Much work is going on presently to improve the crystal growth and packaging of the Eu 2+ activated SrI 2 scintillator, thanks to its excellent scintillation properties like high light yield and good energy resolution. Larger crystals are needed for spectroscopic applications, and proper packaging is important for long-time field use and application in other areas due to its hygroscopic nature. In this paper, we report on the successful growth of a SrI 2Eu[6mol%] single crystal in silica ampoule to prevent melt hydration and oxygen contamination using the vertical Bridgman technique. The scintillation properties of a 0.314 cm 3SrI 2:Eu sample are presented, showing a light output of ∼ 80000 ph/MeV. A 360 μm sample was investigated for X-ray imaging applications; we also show how the sample was prepared for the measurement and the result of this preliminary investigation. © 2012 IEEE.

Riedel A., Dos Santos Rolo T., Cecilia A., Van De Kamp T.

in Zoological Journal of the Linnean Society, 165 (2012) 773-794. DOI:10.1111/j.1096-3642.2012.00825.x

Abstract

Two genera of extinct weevils, Sayrevilleus Gratshev & Zherikhin from Cretaceous New Jersey amber and Baltocar Kuschel from Eocene Baltic amber, are recognized as close relatives based on similarities revealed by the use of synchrotron tomography and the availability of new amber inclusions. The subfamily Sayrevilleinae Legalov stat. nov. is characterized by possessing mandibles with an external cutting edge and an inner blunt edge. The subfamily is placed in the family Attelabidae (s.l.), although some characters also suggest a possible relationship with the ‘higher weevils’ comprising Caridae, Brentidae, and Curculionidae. Sayrevilleus is transferred from the tribe Auletini of Rhynchitinae to Sayrevilleinae, and Sayrevilleus grimaldii Gratshev & Zherikhin is redescribed. Baltocar Kuschel is transferred from Caridae to Sayrevilleinae and revised, its type species, Baltocar succinicus (Voss), is redescribed and three new species, Baltocar groehni Riedel sp. nov., Baltocar hoffeinsorum Riedel sp. nov., and Baltocar subnudus Riedel sp. nov. are described based on eight well-preserved inclusions. The genera Orapauletes Legalov and Zherichiniletes Legalov previously assigned to Sayrevilleini are regarded as Curculionoidea incertae sedis. The Sayrevilleinae were distributed over areas of North America and Europe at least since the Late Cretaceous (c.90Mya) and were probably relatively diverse until the Eocene (c.44Mya). It is speculated that they became extinct through competition with Curculionidae, which used a similar oviposition strategy. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165, 773-794. © 2012 The Linnean Society of London.

Myagotin A., Ershov A., Helfen L., Verdejo R., Belyaev A., Baumbach T.

in Journal of Synchrotron Radiation, 19 (2012) 483-491. DOI:10.1107/S0909049512015099

Abstract

A novel image-processing procedure is proposed for the analysis of sequences of two-dimensional projection images. Sudden events like the merging of bubbles in an evolving foam can be detected and spatio-temporally located in a given projection image sequence. The procedure is based on optical flow computations extended by a forward-backward check for each time step. Compared with prior methods, efficient suppression of noise or false events is achieved owing to uniform foam motion, and the reliability of detection is thus increased. The applicability of the proposed procedure in combination with synchrotron radiography is illustrated by a series of characteristic studies of foams of different kind. First, the detection of single-bubble collapses in aqueous foams is considered. Second, a spatial distribution of coalescence events in metals foamed in casting molds is estimated. Finally, the structural stability of polymer foams containing admixed solid nanoparticles is examined. © 2012 International Union of Crystallography.

Altapova V.R., Ershov A., Rolo T.d.S., Reznikova E., Mohr J., Pivovarov Y.L., Pichugin V.F., Baumbach G.T.

in Journal of Surface Investigation, 6 (2012) 394-397. DOI:10.1134/S1027451012050035

Abstract

The imaging methods used at the ANKA Synchrotron Light Source (Institute for Synchrotron Radiation, Karlsruhe Institute of Technology) are briefly reviewed. Examples of recent applications of the phase-contrast imaging method using a grating interferometer and fast radiography with optic flow data analysis to study static and moving biological objects are presented. © 2012 Pleiades Publishing, Ltd.

Alaribe L., Disch C., Fauler A., Engels R., Keller E., Cecilia A., Rolo T.D.S., Hamann E., Fiederle M.

in IEEE Nuclear Science Symposium Conference Record (2012) 1567-1571, 6154633. DOI:10.1109/NSSMIC.2011.6154633

Abstract

Currently, there is a great interest in the research and development of SrI 2:Eu 2+ scintillating crystals. The high light yield, high density (4.6 g/cm 3) and high effective atomic number (49.4) make the Eu 2+-activated SrI 2 suitable for use as x-ray and gamma ray detector. SrI 2:Eu 2+-single crystals were grown with the vertical Bridgman technique in silica ampoules to prevent melt hydration and oxygen contamination during the crystal growth. For measurements, crystals were hermetically encapsulated in aluminum containers with quartz glass optical windows. The radioluminescence spectra of the SrI 2:Eu 2+-samples show maximum at 431 nm and 432 nm for the 5% and 6% dopant concentrations respectively. The light yield of the bulk samples was up to 80 000 photons/MeV and up to 119 000 photons/MeV for a 360 μm sample integrated in an x-ray imaging setup. © 2011 IEEE.

Alaribe L., Disch C., Fauler A., Engels R., Keller E., Cecilia A., Dos Santos Rolo T., Fiederle M.

in Materials Research Society Symposium Proceedings, 1341 (2012) 21-26. DOI:10.1557/opl.2011.1275

Abstract

Eu 2+- activated strontium iodide is a promising material for x-ray and gamma ray detector. A lot of difficulties are though encountered growing strontium iodide crystals due to the high oxygen-sensitivity, hygroscopic property and high impurity concentration. Single crystals of Srl 2:Eu were grown from zone refined starting materials in silica ampoules. The crystals showed good optical qualities. The light yield of two samples cut from the same ingot was determined to be 53 000 photons/MeV and 119±22 photons/keV for a 0.4 cm 3 sample and a 360 μm sample respectively, indicating some level of light trapping in the bulk sample. Keywords: scintillator, Bridgman growth method, energy resolution. © 2011 Materials Research Society.

Chilingaryan S., Kopmann A., Mirone A., Dos Santos Rolo T., Vogelgesang M.

in SC’11 – Proceedings of the 2011 High Performance Computing Networking, Storage and Analysis Companion, Co-located with SC’11 (2011) 51-52. DOI:10.1145/2148600.2148624

Abstract

X-ray tomography has been proven to be a valuable tool for understanding internal, otherwise invisible, mechanisms in biology and other fields. Recent advances in digital detector technology enabled investigation of dynamic processes in 3D with a temporal resolution down to the milliseconds range. Unfortunately it requires computationally intensive recon- struction algorithms with long post-processing times. We have optimized the reconstruction software employed at the micro-tomography beamlines at KIT and ESRF. Using a 4 stage pipelined architecture and the computational power of modern graphic cards, we were able to reduce the processing time by a factor 75 with a single server. The time required to reconstruct a typical 3D image is reduced down to several seconds only and online visualization is possible for the first time.Copyright is held by the author/owner(s).

Danilewsky A.N., Wittge J., Hess A., Croll A., Rack A., Allen D., McNally P., Dos Santos Rolo T., Vagovic P., Baumbach T., Garagorri J., Elizalde M.R., Tanner B.K.

in Physica Status Solidi (A) Applications and Materials Science, 208 (2011) 2499-2504. DOI:10.1002/pssa.201184264

Abstract

We describe a rapid digital system for X-ray diffraction imaging and demonstrate its application to the real-time identification of edge defects in a silicon wafer that had been subjected to rapid thermal annealing. The application of the system to the in situ study of slip nucleation at the location of mechanical wafer defects, indents and a thermocouple, and the subsequent dislocation dynamics is presented. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Altapova V., Butzer J., Rolo T.D.S., Vagovic P., Cecilia A., Moosmann J., Kenntner J., Mohr J., Pelliccia D., Pichugin V.F., Baumbach T.

in Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 648 (2011). DOI:10.1016/j.nima.2010.12.218

Abstract

One of the most promising methods of phase-contrast imaging is the Talbot grating interferometry. We report about the optimization of the method for fast imaging, requiring reduced exposure times by keeping sufficient imaging contrast. To do this a new Talbot interferometer working with a broad energy bandwidth beam has been installed at the TopoTomo beamline at ANKA. We demonstrate the method with a filtered white beam and without the need of a source grating that is commonly used at moderate-emittance synchrotron sources. Taking advantage of a higher photon flux, the exposure time is significantly reduced. At the same time, images obtained with this setup show a sufficient visibility contrast of 25% on average, which opens the way for new applications in real-time measurements. © 2010 Elsevier B.V. All rights reserved.

Cecilia A., Rack A., Douissard P.-A., Martin T., Dos Santos Rolo T., Vagovic P., Hamann E., Van De Kamp T., Riedel A., Fiederle M., Baumbach T.

in Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 648 (2011). DOI:10.1016/j.nima.2010.10.150

Abstract

Within the project ScinTAX of the 6th framework program (FP6) of the European Commission (SCINTAX – STRP 033 427) we have developed a new thin single crystal scintillator for high-resolution X-ray imaging. The scintillator is based on a Tb-doped Lu2SiO5 (LSO) film epitaxially grown on an adapted substrate. The high density, effective atomic number and light yield of the scintillating LSO significantly improves the efficiency of the X-ray imaging detectors currently used in synchrotron micro-imaging applications. In this work we present the characterization of the scintillating LSO films in terms of their spatial resolution performance and we provide two examples of high spatial and high temporal resolution applications. © 2010 Elsevier B.V. All rights reserved.