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Stora Höga, Sweden

Josic L.,Paul Scherrer Institute | Steuwer A.,Paul Scherrer Institute | Lehmann E.,ESS Scandinavia
Applied Physics A: Materials Science and Processing | Year: 2010

Energy selective neutron radiography was performed to describe a complex structure in polycrystalline materials. Experiments were performed with currently the highest energy and spatial resolutions achieved simultaneously, by employing a double crystal monochromator for selecting narrow energy bands from the initially polychromatic neutron beam and the neutron absorbing scintillator screen coupled with the cooled CCD camera as a detection system. It was shown that the detailed structure of the welded steel sample can be visualized and quantified by performing energy selective neutron imaging in the cold energy range, where elastic coherent scattering dominates the total cross section of the sample, showing characteristic Bragg edges. With the maps of crystallographic orientations over the sample area of 2 × 2 cm2 and thickness 11.2 mm, obtained directly from radiographs, the complex structure was energy resolved with a spatial resolution of 50 μm. © Springer-Verlag 2010.


Tremsin A.S.,University of California at Berkeley | McPhate J.B.,University of California at Berkeley | Vallerga J.V.,University of California at Berkeley | Siegmund O.H.W.,University of California at Berkeley | And 3 more authors.
IEEE Sensors Journal | Year: 2011

High-resolution neutron counting sensors with microchannel plates coupled to a Timepix readout enable high spatial (∼55 μm) and temporal (∼1 μs) accuracy for each detected thermal and cold neutron. One of the attractive applications for those sensors is the high-resolution strain mapping in engineering samples through transmission Bragg edge diffraction. The unique combination of high detection efficiency (up to 70%), high spatial and temporal resolution of , detectors enable ∼100μ m strain mapping with ∼100μstrain accuracy. We present the results of proof of principle measurements performed at ROTAX beamline at ISIS spallation neutron source. Strain map of a bent steel sample is measured with very high spatial resolution. The same sensors enable high-resolution nondestructive studies in such diverse areas as neutron microtomography, dynamics of fuel injection, material composition, archaeology, water propagation and many others. © 2011 IEEE.


Tremsin A.S.,University of California at Berkeley | McPhate J.B.,University of California at Berkeley | Vallerga J.V.,University of California at Berkeley | Siegmund O.H.W.,University of California at Berkeley | And 3 more authors.
Proceedings of IEEE Sensors | Year: 2010

High resolution neutron counting sensors with microchannel plates coupled to a Timepix readout enable high spatial (∼55 μm) and temporal (∼1 μs) accuracy for each detected thermal and cold neutron. One of the attractive applications for those sensors is the high resolution strain mapping in engineering samples through transmission Bragg edge diffraction. The unique combination of high detection efficiency (up to 70%), high spatial and temporal resolution of MCP detectors enable ∼100 μm strain mapping with ∼100 μstrain accuracy. We present the results of proof of principle measurements performed at ROTAX beamline at ISIS spallation neutron source. Strain map of a bent steel sample is measured with very high spatial resolution. The same sensors enable high resolution non-destructive studies in such diverse areas as neutron microtomography, dynamics of fuel injection, material composition, archaeology, water propagation and many others. ©2010 IEEE.


Tremsin A.S.,University of California at Berkeley | McPhate J.B.,University of California at Berkeley | Steuwer A.,ESS Scandinavia | Steuwer A.,Nelson Mandela Metropolitan University | And 6 more authors.
Strain | Year: 2012

Conventional neutron radiography can be strongly enhanced by obtaining Bragg-edge information spatially correlated with the attenuation coefficient. This can now be achieved through time-of-flight techniques at pulsed neutron sources, utilising a neutron counting detector with high-spatial and high-temporal resolution. In these measurements, the positions of Bragg edges can in principle be obtained for each 55 × 55 μm 2 pixel of the radiographic image. The combination of both Bragg-edge and attenuation information enables high spatial resolution studies to be carried out on material composition, phase transitions, texture variations, as well as residual strain mapping. In this article, we present the results of high-resolution strain maps of a ferritic steel cantilever sample measured at different loads by both transmission and conventional diffraction modes, as well as strains in an austenitic steel compact-tension (CT) crack sample. The proof of principle experiments performed on the ENGIN-X beamline on a bent cantilever arrangement resulting in a uni-axial stress field verified that the strain values measured in diffraction and transmission mode are in good agreement. The characteristics of the transmission mode detector as well as the measured strain maps and future possibilities of this technology are discussed. © 2011 Blackwell Publishing Ltd.


Ruiz-Hervias J.,Technical University of Madrid | Steuwer A.,ESS Scandinavia | Steuwer A.,Nelson Mandela Metropolitan University | Gurauskis J.,CSIC - Institute of Materials Science | And 2 more authors.
Materials Science Forum | Year: 2010

Residual strain profiles were measured by synchrotron X-ray radiation in Al2O3/Ystabilized ZrO2 (YSZ) ceramic laminates. Different stacking sequences were employed, including alternating layers containing 5 and 40 vol.% YSZ. Residual strains were found to be fairly constant within each layer; although they change at the interface between layers with different compositions. Different behaviour is observed for the strains along the in-plane and normal directions. © (2010) Trans Tech Publications.

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