TY - JOUR A1 - Al-Falahat, A.M. A1 - Kupsch, Andreas A1 - Hentschel, M.P. A1 - Lange, A. A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Manke, I. T1 - Correction approach of detector backlighting in radiography JF - Review of Scientific Instruments N2 - In various kinds of radiography, deficient transmission imaging may occur due to backlighting inside the detector itself arising from light or radiation scattering. The related intensity mismatches barely disturb the high resolution contrast, but its long range nature results in reduced attenuation levels which are often disregarded. Based on X-ray observations and an empirical formalism, a procedure is developed for a first order correction of detector backlighting. A backlighting factor is modeled as a function of the relative detector coverage by the sample projection. Different cases of sample transmission are regarded at different backlight factors and detector coverage. The additional intensity of backlighting may strongly affect the values of materials’ attenuation up to a few 10%. The presented scenario provides a comfortable procedure for corrections of X-ray or neutron transmission imaging data. KW - X-ray imaging KW - Neutron imaging KW - Radiology KW - Backlighting KW - Digital detector array PY - 2019 DO - https://doi.org/10.1063/1.5097170 SN - 0034-6748 VL - 90 IS - 12 SP - 125108 PB - American Institute of Physics CY - Melville, NY, USA AN - OPUS4-50217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dabah, Eitan A1 - Pfretzschner, Beate A1 - Schaupp, Thomas A1 - Kardjilov, N. A1 - Manke, I. A1 - Boin, M. A1 - Woracek, R. A1 - Griesche, Axel T1 - Time-resolved Bragg-edge neutron radiography for observing martensitic phase transformation from austenitized super martensitic steel JF - Journal of Materials Science N2 - Neutron Bragg-edge imaging was applied for the visualization of a γ-Austenite to α'-martensite phase transformation. In the present study, a super martensitic stainless steel sample was heated until complete austenitization and was subsequently cooled down to room temperature. The martensitic phase Transformation started at Ms = 190 °C. Using a monochromatic neutron beam with λ = 0.390 nm, the transmitted intensity was significantly reduced during cooling below Ms, since the emerging martensitic phase has a higher attenuation coefficient than the austenitic phase at this wavelength. The phase Transformation process was visualized by filming the transmission images from a scintillator screen with a CCD camera with a temporal resolution of 30 s and a spatial resolution of 100 µm. KW - Neutron imaging KW - Bragg-edge imaging KW - Phase transformation PY - 2017 DO - https://doi.org/10.1007/s10853-016-0642-9 SN - 0022-2461 SN - 1573-4803 VL - 52 IS - 6 SP - 3490 EP - 3496 AN - OPUS4-38574 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jamro, R. A1 - Mente, Tobias A1 - Kardjilov, N. A1 - Markötter, Henning A1 - Al-Falahat, Ala'A. M. A1 - Woracek, R. A1 - Manke, I. A1 - Griesche, Axel T1 - Temperature distribution during welding measured by neutron imaging JF - Journal of Physics: Conference Series N2 - This study was carried out to investigate the neutron transmission signal as a function of sample temperature during a welding process. A theoretical description that includes the Debye-Waller factor was used to describe the temperature influence on the neutron crosssections. Neutron imaging using a monochromatic beam helps to observe transmission variations related to the material temperature. In-situ neutron imaging of welding experiments show the distribution of the temperature in bulk steel samples. The performed finite element modelling of expected temperature distributions shows good agreement with the obtained experimental data. KW - Neutron imaging KW - Debye-Waller-Faktor PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586268 DO - https://doi.org/10.1088/1742-6596/2605/1/012026 VL - 2605 SP - 1 EP - 10 PB - IOP Publishing Ltd. AN - OPUS4-58626 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kardjilov, N A1 - Manke, I A1 - Hilger, A A1 - Arlt, T A1 - Bradbury, R A1 - Markötter, Henning A1 - Woracek, R A1 - Strobel, M A1 - Treimer, W A1 - Banhart, J T1 - The Neutron Imaging Instrument CONRAD — Post‐Operational Review JF - Journal of imaging N2 - The neutron imaging instrument CONRAD was operated as a part of the user program of the research reactor BER‐II at Helmholtz‐Zentrum Berlin (HZB) from 2005 to 2020. The Instrument was designed to use the neutron flux from the cold source of the reactor, transported by a curved neutron guide. The pure cold neutron spectrum provided a great advantage in the use of different neutron optical components such as focusing lenses and guides, solid‐state polarizers, Monochromators and phase gratings. The flexible setup of the instrument allowed for implementation of new methods including wavelength‐selective, dark‐field, phase‐contrast and imaging with polarized neutrons. In summary, these developments helped to attract a large number of scientists and industrial customers, who were introduced to neutron imaging and subsequently contributed to the Expansion of the neutron imaging community. KW - Neutron imaging KW - Neutron scattering KW - Neutron instrument KW - Tomography PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-534190 DO - https://doi.org/10.3390/ jimaging7010011 VL - 7 IS - 11 SP - 7010011 PB - MDPI AN - OPUS4-53419 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manke, I. A1 - Kardjilov, N. A1 - Schäfer, R. A1 - Hilger, A. A1 - Grothausmann, R. A1 - Strobl, M. A1 - Dawson, M. A1 - Grünzweig, C. A1 - Tötzke, C. A1 - David, C. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Banhart, J. T1 - Three-dimensional imaging of magnetic domains with neutron grating interferometry JF - Physics procedia N2 - This paper gives a brief overview on3D imaging of magnetic domains with shearing grating neutron tomography. We investigated the three-dimensional distribution of magnetic domain walls in the bulk of a wedge-shaped FeSi single crystal. The width of the magnetic domains wasanalyzed at different locations within the crystal. Magnetic domains close to the tip of the wedge are much smaller than in the bulk. Furthermore, the three-dimensional shape of individual domains wasinvestigated. We discuss prospects and limitations of the applied measurement technique. KW - Neutron imaging KW - Tomography KW - Magnetic domains KW - Grating interferometry KW - Darkfield imaging KW - Shearing gratings KW - Talbot-Lau KW - Three-dimensional data quantification KW - Tomographic reconstruction PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-341919 DO - https://doi.org/10.1016/j.phpro.2015.07.057 SN - 1875-3892 VL - 69 SP - 404 EP - 412 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-34191 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Markötter, H. A1 - Manke, I. A1 - Kuhn, R. A1 - Arlt, Tobias A1 - Kardjilov, N. A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hartnig, C. A1 - Scholta, J. A1 - Banhart, J. T1 - Neutron tomographic investigations of water distributions in polymer electrolyte membrane fuel cell stacks JF - Journal of power sources N2 - Neutron tomography was applied to study the 3D water distribution in full polymer electrolyte membrane fuel cell (PEMFC) stacks. The water distribution after switch-off of the fuel cell was analyzed over a period of 36 h. We found a slowly increasing water amount in the fuel cell, but only few changes within a time period of 5 h, which is about the time necessary for neutron tomography. In this way, the requirement for successful tomography was obtained. It is demonstrated how the quasi in-situ tomography technique enables us to study the water content in individual flow field channels of three-fold stacks. Flow field as well as stack design issues are addressed by this visualization method showing weak points due to a non-uniform water distribution that can be identified by means of neutron imaging. KW - Radiography KW - Tomography KW - Neutron imaging KW - Polymer electrolyte membrane fuel cell (PEMFC) KW - Manifold stack KW - Water management PY - 2012 DO - https://doi.org/10.1016/j.jpowsour.2012.07.043 SN - 0378-7753 VL - 219 SP - 120 EP - 125 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-26317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohseninia, A A1 - Eppler, M A1 - Kartouzian, D A1 - Markötter, Henning A1 - Kardjilov, N A1 - Wilhelm, F A1 - Scholta, J A1 - Manke, I T1 - PTFE Content in Catalyst Layers and Microporous Layers: Effect on Performance and Water Distribution in Polymer Electrolyte Membrane Fuel Cells JF - Journal of the Electrochemical Society N2 - This work describes the effects of catalyst layers (CLs) consisting of hydrophobic PTFE on the performance and water management of PEM fuel cells. Catalyst inks with various PTFE contents were coated on Nafion membranes and characterized using contact angle measurements, SEX-EDX, and mercury porosimetry. Fuel cell tests and electrochemical impedance spectroscopy (EIS) were conducted under varying operating conditions for the prepared materials. At dry conditions, CLs with 5 wt.% PTFE were advantageous for cell performance due to improved membrane hydration, whereas under humid conditions and high air flow rates CLs with 10 wt.% PTFE improved the performance in high current density region. Higher PTFE contents (⩾20 wt.%) increased the mass transport resistance due to reduced porosity of the CLs structure. Operando neutron radiography was utilized to study the effects of hydrophobicity gradients within CLs and cathode microporous layer (MPLC) on liquid water distribution. More hydrophobic CLs increased the water content in adjacent layers and improved performance, especially at dry conditions. MPLC with higher PTFE contents increased the overall liquid water within the CLs and GDLs and escalated the water transfer to the anode side. Furthermore, the role of back-diffusion transport mechanism on water distribution was identified for the investigated cells. KW - Neutron imaging KW - Polymer Electrolyte Membrane Fuel Cell KW - Catalyst Layer KW - Microporous Layer KW - Water Distribution PY - 2021 DO - https://doi.org/10.1149/1945-7111/abec53 VL - 168 IS - 3 SP - 034509 PB - IOP Science AN - OPUS4-52402 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfretzschner, Beate A1 - Schaupp, Thomas A1 - Griesche, Axel T1 - Hydrogen in Metals Visualized by Neutron Imaging JF - Corrosion N2 - Neutron cameras allow visualizing hydrogen distributions with radiographic or tomographic imaging methods in iron (and steel) and many other metals. The necessary contrast between hydrogen and these metals stems from the high difference in the total neutron cross section of both elements. This allows, e.g., the in situ measurement of hydrogen mass flow inside cm thick metal samples with a temporal resolution of at best 10 s using neutron radiography as well as the quantitative measurement of hydrogen accumulations, e.g., at the crack’s inner surfaces in hydrogen embrittled iron samples with neutron tomography. This new quality of the information on a micrometer scale allows new insights for the analysis of hydrogen-assisted damage mechanisms. Further, this method is non-destructive and provides local information in situ and in three dimensions with a spatial resolution of 20 μm - 30 μm. In this contribution, we give a short historical overview of neutron imaging and show examples that demonstrate the spatial and temporal resolution of the neutron radiography and tomography methods in order to visualize and quantify hydrogen accumulations, absorption processes, and diffusion. The examples are taken from the works of researchers dealing with titanium, palladium, zirconium, and iron or steel. More detailed descriptions of the experimental and analytic procedures are given for hydrogen detection using radiography and tomography on iron and steel samples. KW - Hydrogen assisted cracking KW - Neutron imaging PY - 2019 DO - https://doi.org/10.5006/3104 SN - 0010-9312 VL - 75 IS - 8 SP - 903 EP - 910 PB - NACE International AN - OPUS4-48775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfretzschner, Beate A1 - Schaupp, Thomas A1 - Hannemann, Andreas A1 - Schultz, Michael A1 - Griesche, Axel T1 - On the Genesis of Artifacts in Neutron Transmission Imaging of Hydrogenous Steel Specimens JF - Journal of Imaging N2 - Hydrogen-charged supermartensitic steel samples were used to systematically investigate imaging artifacts in neutron radiography. Cadmium stencils were placed around the samples to shield the scintillator from excessive neutron radiation and to investigate the influence of the backlight effect. The contribution of scattered neutrons to the total detected intensity was investigated by additionally varying the sample-detector distance and applying a functional correlation between distance and intensity. Furthermore, the influence of the surface roughness on the edge effect due to refraction was investigated. KW - Refraction KW - Neutron imaging KW - Hydrogen KW - Supermartensitic steel KW - Backlight KW - Scattering PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506587 DO - https://doi.org/10.3390/jimaging6040022 VL - 6 IS - 22 SP - 1 EP - 10 PB - MDPI CY - Basel, Switzerland AN - OPUS4-50658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tengattini, A A1 - Kardjilov, N A1 - Helfen, L A1 - Douissard, P A A1 - Lenoir, N A1 - Markötter, Henning A1 - Hilger, A A1 - Arlt, T A1 - Paulisch, M A1 - Turek, T A1 - Manke, Ingo T1 - Compact and versatile neutron imaging detector with sub-4μm spatial resolution based on a single-crystal thin-film scintillator JF - Optics Express N2 - A large and increasing number of scientific domains pushes for high neutron imaging resolution achieved in reasonable times. Here we present the principle, design and performance of a detector based on infinity corrected optics combined with a crystalline Gd3Ga5O12 : Eu scintillator, which provides an isotropic sub-4 μm true resolution. The exposure times are only of a few minutes per image. This is made possible also by the uniquely intense cold neutron flux available at the imaging beamline NeXT-Grenoble. These comparatively rapid acquisitions are compatible with multiple high quality tomographic acquisitions, opening new venues for in-operando testing, as briefly exemplified here. KW - Neutron imaging KW - Scintillator KW - Resolution PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-549836 DO - https://doi.org/10.1364/oe.448932 VL - 30 IS - 9 SP - 14461 EP - 14477 PB - Optica CY - Washington, DC AN - OPUS4-54983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -