Refraction contrast imaging and edge effects in neutron radiography

Tremsin, Anton S.; Lehmann, Eberhard; Kardjilov, Nikolay; Ströbl, Markus; Manke, Ingo; McPhate, Jason B.; Vallerga, J. V.; Siegmund, Oswald H. W.; Feller, W. Bruce

doi:10.1088/1748-0221/7/02/c02047

Cited by 9 publications

(8 citation statements)

References 19 publications

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“…This is not to be confused with the additional blur caused by refraction. Here, edge diffraction can be neglected, details on this subject are given in [42][43][44][45][46][47].…”

Section: Spatial Resolution For Unpolarized Neutronsmentioning

confidence: 99%

Determination of the Spatial Resolution in the Case of Imaging Magnetic Fields by Polarized Neutrons

Treimer

Köhler

2021

Applied Sciences

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One of the most important parameters characterizing imaging systems (neutrons, X-rays, etc.) is their spatial resolution. In magnetic field imaging, the spatial resolution depends on the (magnetic) resolution of the depolarization of spin-polarized neutrons. This should be realized by different methods, but they all have in common that a spin-polarizing and spin-analyzing system is part of the resolution function. First a simple and useful method for determining the spatial resolution for unpolarized neutrons is presented, and then methods in the case of imaging with polarized neutrons. Spatial resolution in the case of polarized neutron imaging is fundamentally different from ‘classical’ spatial resolution. Because of π-periodicity, the shortest path along which a spin-flip can occur is a measure of ‘magnetic’ spatial resolution. Conversely, the largest detectable magnetic field (B-field) within a given path length is also a measure of magnetic spatial resolution. This refers to the spatial resolution in the flight direction of the neutrons (Δy). The Δx and Δz refers to the spatial resolution in x- or z-direction; however, in these cases a different method must be used. Therefore, two independent methods are used to distinguish longitudinal and lateral spatial resolution, one method to determine the modulation transfer function (MTF) by recording the frequency-dependent fringe contrast of magnetic field images of a coil (longitudinal spatial resolution), and the second method, to observe the fringe displacement at the detector as a function of magnetic motion, provided that the accuracy of the motion is much better than the pixel size (at least half the pixel size) of the detector (lateral spatial resolution). The second method is a convolution of the fringe pattern with the pixel array of the detector.

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“…This is not to be confused with the additional blur caused by refraction. Here, edge diffraction can be neglected, details on this subject are given in [42][43][44][45][46][47].…”

Section: Spatial Resolution For Unpolarized Neutronsmentioning

confidence: 99%

Determination of the Spatial Resolution in the Case of Imaging Magnetic Fields by Polarized Neutrons

Treimer

Köhler

2021

Applied Sciences

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“…Neutron imaging experiments combining a high degree of beam collimation, a cold beam spectrum and a high spatial resolution detector, can exhibit image artifacts related to neutron refraction and reflection [27,28]. The edge enhancement effects, for example, can be beneficial for the imaging analysis as they improve separation of various parts within the image.…”

Section: Edge Effects and Image Artifactsmentioning

confidence: 99%

“…The edge enhancement effects, for example, can be beneficial for the imaging analysis as they improve separation of various parts within the image. Refraction-enhanced imaging with neutron collimating optics was suggested previously [28], which can be attractive for the objects where variation of attenuation contrast is not sufficient. However, in some experiments, these edge effects can introduce image artifacts, as in the case of tomographic reconstruction and need be taken into account.…”

Section: Edge Effects and Image Artifactsmentioning

confidence: 99%

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High resolution neutron imaging capabilities at BOA beamline at Paul Scherrer Institut

Tremsin

Morgano

Panzner

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tThe cold neutron spectrum of the Beamline for neutron Optics and other Applications (BOA) at Paul Scherrer Institut enables high contrast neutron imaging because neutron cross sections for many materials increase with neutron wavelength. However, for many neutron imaging applications, spatial resolution can be as important as contrast. In this paper the neutron transmission imaging capabilities of an MCP/Timepix detector installed at the BOA beamline are presented, demonstrating the possibilities for studying sub-20 mm features in various samples. In addition to conventional neutron radiography and microtomography, the high degree of neutron polarization at the BOA beamline can be very attractive for imaging of magnetic fields, as demonstrated by our measurements. We also show that a collimated cold neutron beamline combined with a high resolution detector can produce image artifacts, (e.g. edge enhancements) due to neutron refraction and scattering. The results of our experiments indicate that the BOA beamline is a valuable addition to neutron imaging facilities, providing improved and sometimes unique capabilities for non-destructive studies with cold neutrons.

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“…The observed effective transmission is hardly reduced by scattering effects which can hence often be neglected in the data analysis. [21][22][23] Neutron radiography and fluorescence imaging have been combined before. 19,24 In these previous studies, however, the samples had to be moved out of the neutron beam to take fluorescence images.…”

Section: Introductionmentioning

confidence: 99%

Neutron, fluorescence, and optical imaging: An in situ combination of complementary techniques

Wagner

Börgardts

Grünzweig

et al. 2015

Review of Scientific Instruments

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An apparatus which enables the simultaneous combination of three complementary imaging techniques, optical imaging, fluorescence imaging, and neutron radiography, is presented. While each individual technique can provide information on certain aspects of the sample and their time evolution, a combination of the three techniques in one setup provides a more complete and consistent data set. The setup can be used in transmission and reflection modes and thus with optically transparent as well as opaque samples. Its capabilities are illustrated with two examples. A polymer hydrogel represents a transparent sample and the diffusion of fluorescent particles into and through this polymer matrix is followed. In reflection mode, the absorption of solvent by a nile red-functionalized mesoporous silica powder and the corresponding change in fluorescent signal are studied.

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Refraction contrast imaging and edge effects in neutron radiography

Cited by 9 publications

References 19 publications

Determination of the Spatial Resolution in the Case of Imaging Magnetic Fields by Polarized Neutrons

Determination of the Spatial Resolution in the Case of Imaging Magnetic Fields by Polarized Neutrons

High resolution neutron imaging capabilities at BOA beamline at Paul Scherrer Institut

Neutron, fluorescence, and optical imaging: An in situ combination of complementary techniques

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