Special Issue "Neutron Imaging"

A special issue of Journal of Imaging (ISSN 2313-433X).

Deadline for manuscript submissions: closed (31 October 2017)

Special Issue Editor

Guest Editor
Dr. Daniel S. Hussey

National Institute of Standards and Technology, Gaithersburg, MD 20899-8461, USA
Website | E-Mail
Interests: neutron imaging; fuel cells; neutron optics; phase imaging; dark field imaging; strain imaging; porous media; electrochemistry; neutron detectors; tomography

Special Issue Information

Dear Colleagues,

The field of neutron imaging is rapidly developing multimodal and multiscale methods. This development is spurred by advances in detector technology, facile microfabrication of neutron optical components, ability to analyze large image data sets, and the merging and adoption of methods from other disciplines. These new methods are able to uniquely interrogate samples thanks to the penetrating power of thermal and cold neutrons. With the ability to readily transmit several centimeters of many common metals, neutron imaging methods reveal buried and bulk structures or study materials within sample environments, such as pressure vessels, furnaces, magnets, and cryostats. The intent of the “Neutron Imaging” Special Issue is to present a snap shot of the field’s development by covering a range of topics that includes method development and applications in the areas:

•    Imaging detectors and instrumentation
•    Bragg edge imaging and diffractive contrast tomography
•    Neutron phase and dark-field imaging
•    Magnetic contrast imaging
•    Energy selective methods
•    Tomography and multimodal imaging

Papers must be original research of novel results or a suitable review article of the current state-of-the-art.

Dr. Daniel S. Hussey
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Imaging is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) is waived for well-prepared manuscripts submitted to this issue. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Neutron phase imaging
  • Dark-field imaging
  • Bragg edge imaging
  • Tomography
  • Magnetic imaging
  • Neutron imaging detector
  • Instrumentation
  • Diffraction contrast tomography
  • Multimodal imaging
  • Energy selective imaging

Published Papers (18 papers)

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Research

Jump to: Review

Open AccessArticle Investigation of a Monturaqui Impactite by Means of Bi-Modal X-ray and Neutron Tomography
J. Imaging 2018, 4(5), 72; https://doi.org/10.3390/jimaging4050072
Received: 21 March 2018 / Revised: 11 May 2018 / Accepted: 12 May 2018 / Published: 18 May 2018
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Abstract
X-ray and neutron tomography are applied as a bi-modal approach for the 3D characterisation of a Monturaqui impactite formed by shock metamorphism during the impact of an iron meteorite with the target rocks in the Monturaqui crater (Chile). The particular impactite exhibits structural
[...] Read more.
X-ray and neutron tomography are applied as a bi-modal approach for the 3D characterisation of a Monturaqui impactite formed by shock metamorphism during the impact of an iron meteorite with the target rocks in the Monturaqui crater (Chile). The particular impactite exhibits structural heterogeneities on many length scales: its composition is dominated by silicate-based glassy and crystalline materials with voids and Fe/Ni-metal and oxihydroxides particles generally smaller than 1 mm in diameter. The non-destructive investigation allowed us to apply a novel bi-modal imaging approach that provides a more detailed and quantitative understanding of the structural and chemical composition compared to standard single mode imaging methods, as X-ray and neutron interaction with matter results in different attenuation coefficients with a non-linear relation. The X-ray and neutron data sets have been registered, and used for material segmentation, porosity and metallic content characterization. The bimodal data enabled the segmentation of a large number of different materials, their morphology as well as distribution in the specimen including the quantification of volume fractions. The 3D data revealed an evaporite type of material in the impactite not noticed in previous studies. The present study is exemplary in demonstrating the potential for non-destructive characterisation of key features of complex multi-phase objects such as impactites. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Demonstration of Focusing Wolter Mirrors for Neutron Phase and Magnetic Imaging
J. Imaging 2018, 4(3), 50; https://doi.org/10.3390/jimaging4030050
Received: 1 November 2017 / Revised: 1 March 2018 / Accepted: 2 March 2018 / Published: 6 March 2018
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Abstract
Image-forming focusing mirrors were employed to demonstrate their applicability to two different modalities of neutron imaging, phase imaging with a far-field interferometer, and magnetic-field imaging through the manipulation of the neutron beam polarization. For the magnetic imaging, the rotation of the neutron polarization
[...] Read more.
Image-forming focusing mirrors were employed to demonstrate their applicability to two different modalities of neutron imaging, phase imaging with a far-field interferometer, and magnetic-field imaging through the manipulation of the neutron beam polarization. For the magnetic imaging, the rotation of the neutron polarization in the magnetic field was measured by placing a solenoid at the focus of the mirrors. The beam was polarized upstream of the solenoid, while the spin analyzer was situated between the solenoid and the mirrors. Such a polarized neutron microscope provides a path toward considerably improved spatial resolution in neutron imaging of magnetic materials. For the phase imaging, we show that the focusing mirrors preserve the beam coherence and the path-length differences that give rise to the far-field moiré pattern. We demonstrated that the visibility of the moiré pattern is modified by small angle scattering from a highly porous foam. This experiment demonstrates the feasibility of using Wolter optics to significantly improve the spatial resolution of the far-field interferometer. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Energy-Resolved Neutron Imaging for Reconstruction of Strain Introduced by Cold Working
J. Imaging 2018, 4(3), 48; https://doi.org/10.3390/jimaging4030048
Received: 9 December 2017 / Revised: 22 February 2018 / Accepted: 23 February 2018 / Published: 28 February 2018
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Abstract
Energy-resolved neutron transmission imaging is used to reconstruct maps of residual strains in drilled and cold-expanded holes in 5-mm and 6.4-mm-thick aluminum plates. The possibility of measuring the positions of Bragg edges in the transmission spectrum in each 55 × 55 µm2
[...] Read more.
Energy-resolved neutron transmission imaging is used to reconstruct maps of residual strains in drilled and cold-expanded holes in 5-mm and 6.4-mm-thick aluminum plates. The possibility of measuring the positions of Bragg edges in the transmission spectrum in each 55 × 55 µm2 pixel is utilized in the reconstruction of the strain distribution within the entire imaged area of the sample, all from a single measurement. Although the reconstructed strain is averaged through the sample thickness, this technique reveals strain asymmetries within the sample and thus provides information complementary to other well-established non-destructive testing methods. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Time-of-Flight Neutron Imaging on IMAT@ISIS: A New User Facility for Materials Science
J. Imaging 2018, 4(3), 47; https://doi.org/10.3390/jimaging4030047
Received: 11 January 2018 / Revised: 6 February 2018 / Accepted: 23 February 2018 / Published: 28 February 2018
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Abstract
The cold neutron imaging and diffraction instrument IMAT at the second target station of the pulsed neutron source ISIS is currently being commissioned and prepared for user operation. IMAT will enable white-beam neutron radiography and tomography. One of the benefits of operating on
[...] Read more.
The cold neutron imaging and diffraction instrument IMAT at the second target station of the pulsed neutron source ISIS is currently being commissioned and prepared for user operation. IMAT will enable white-beam neutron radiography and tomography. One of the benefits of operating on a pulsed source is to determine the neutron energy via a time of flight measurement, thus enabling energy-selective and energy-dispersive neutron imaging, for maximizing image contrasts between given materials and for mapping structure and microstructure properties. We survey the hardware and software components for data collection and image analysis on IMAT, and provide a step-by-step procedure for operating the instrument for energy-dispersive imaging using a two-phase metal test object as an example. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Neutron Imaging at LANSCE—From Cold to Ultrafast
J. Imaging 2018, 4(2), 45; https://doi.org/10.3390/jimaging4020045
Received: 5 December 2017 / Revised: 9 February 2018 / Accepted: 9 February 2018 / Published: 23 February 2018
Cited by 1 | PDF Full-text (17080 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, neutron radiography and tomography have been applied at different beam lines at Los Alamos Neutron Science Center (LANSCE), covering a very wide neutron energy range. The field of energy-resolved neutron imaging with epi-thermal neutrons, utilizing neutron absorption resonances for contrast
[...] Read more.
In recent years, neutron radiography and tomography have been applied at different beam lines at Los Alamos Neutron Science Center (LANSCE), covering a very wide neutron energy range. The field of energy-resolved neutron imaging with epi-thermal neutrons, utilizing neutron absorption resonances for contrast as well as quantitative density measurements, was pioneered at the Target 1 (Lujan center), Flight Path 5 beam line and continues to be refined. Applications include: imaging of metallic and ceramic nuclear fuels, fission gas measurements, tomography of fossils and studies of dopants in scintillators. The technique provides the ability to characterize materials opaque to thermal neutrons and to utilize neutron resonance analysis codes to quantify isotopes to within 0.1 atom %. The latter also allows measuring fuel enrichment levels or the pressure of fission gas remotely. More recently, the cold neutron spectrum at the ASTERIX beam line, also located at Target 1, was used to demonstrate phase contrast imaging with pulsed neutrons. This extends the capabilities for imaging of thin and transparent materials at LANSCE. In contrast, high-energy neutron imaging at LANSCE, using unmoderated fast spallation neutrons from Target 4 [Weapons Neutron Research (WNR) facility] has been developed for applications in imaging of dense, thick objects. Using fast (ns), time-of-flight imaging, enables testing and developing imaging at specific, selected MeV neutron energies. The 4FP-60R beam line has been reconfigured with increased shielding and new, larger collimation dedicated to fast neutron imaging. The exploration of ways in which pulsed neutron beams and the time-of-flight method can provide additional benefits is continuing. We will describe the facilities and instruments, present application examples and recent results of all these efforts at LANSCE. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Event Centroiding Applied to Energy-Resolved Neutron Imaging at LANSCE
J. Imaging 2018, 4(2), 40; https://doi.org/10.3390/jimaging4020040
Received: 6 December 2017 / Revised: 9 February 2018 / Accepted: 11 February 2018 / Published: 13 February 2018
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Abstract
The energy-dependence of the neutron cross section provides vastly different contrast mechanisms than polychromatic neutron radiography if neutron energies can be selected for imaging applications. In recent years, energy-resolved neutron imaging (ERNI) with epi-thermal neutrons, utilizing neutron absorption resonances for contrast as well
[...] Read more.
The energy-dependence of the neutron cross section provides vastly different contrast mechanisms than polychromatic neutron radiography if neutron energies can be selected for imaging applications. In recent years, energy-resolved neutron imaging (ERNI) with epi-thermal neutrons, utilizing neutron absorption resonances for contrast as well as for quantitative density measurements, was pioneered at the Flight Path 5 beam line at LANSCE and continues to be refined. Here we present event centroiding, i.e., the determination of the center-of-gravity of a detection event on an imaging detector to allow sub-pixel spatial resolution and apply it to the many frames collected for energy-resolved neutron imaging at a pulsed neutron source. While event centroiding was demonstrated at thermal neutron sources, it has not been applied to energy-resolved neutron imaging, where the energy resolution requires to be preserved, and we present a quantification of the possible resolution as a function of neutron energy. For the 55 μm pixel size of the detector used for this study, we found a resolution improvement from ~80 μm to ~22 μm using pixel centroiding while fully preserving the energy resolution. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Studies of Ancient Russian Cultural Objects Using the Neutron Tomography Method
J. Imaging 2018, 4(2), 25; https://doi.org/10.3390/jimaging4020025
Received: 27 October 2017 / Revised: 18 January 2018 / Accepted: 19 January 2018 / Published: 23 January 2018
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Abstract
Neutron radiography and tomography is a non-destructive method that provides detailed information about the internal structure of cultural heritage objects. The differences in the neutron attenuation coefficients of constituent elements of the studied objects, as well as the application of modern mathematical algorithms
[...] Read more.
Neutron radiography and tomography is a non-destructive method that provides detailed information about the internal structure of cultural heritage objects. The differences in the neutron attenuation coefficients of constituent elements of the studied objects, as well as the application of modern mathematical algorithms to carry out three-dimensional imaging data analysis, allow one to obtain unique information about the spatial distribution of different phases, the presence of internal defects, or the degree of structural degradation inside valuable cultural objects. The results of the neutron studies of several archaeological objects related to different epochs of the Russian history are reported in order to demonstrate the opportunities provided by the neutron tomography method. The obtained 3D structural volume data, as well as the results of the corresponding data analysis, are presented. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessFeature PaperArticle Neutron Imaging with Timepix Coupled Lithium Indium Diselenide
J. Imaging 2018, 4(1), 10; https://doi.org/10.3390/jimaging4010010
Received: 31 October 2017 / Revised: 12 December 2017 / Accepted: 14 December 2017 / Published: 29 December 2017
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Abstract
The material lithium indium diselenide, a single crystal neutron sensitive semiconductor, has demonstrated its capabilities as a high resolution imaging device. The sensor was prepared with a 55 μm pitch array of gold contacts, designed to couple with the Timepix imaging ASIC.
[...] Read more.
The material lithium indium diselenide, a single crystal neutron sensitive semiconductor, has demonstrated its capabilities as a high resolution imaging device. The sensor was prepared with a 55 μ m pitch array of gold contacts, designed to couple with the Timepix imaging ASIC. The resulting device was tested at the High Flux Isotope Reactor, demonstrating a response to cold neutrons when enriched in 95% 6 Li. The imaging system performed a series of experiments resulting in a <200 μ m resolution limit with the Paul Scherrer Institute (PSI) Siemens star mask and a feature resolution of 34 μ m with a knife-edge test. Furthermore, the system was able to resolve the University of Tennessee logo inscribed into a 3D printed 1 cm 3 plastic block. This technology marks the application of high resolution neutron imaging using a direct readout semiconductor. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle In-Situ Imaging of Liquid Phase Separation in Molten Alloys Using Cold Neutrons
J. Imaging 2018, 4(1), 5; https://doi.org/10.3390/jimaging4010005
Received: 31 October 2017 / Revised: 7 December 2017 / Accepted: 7 December 2017 / Published: 25 December 2017
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Abstract
Understanding the liquid phases and solidification behaviors of multicomponent alloy systems becomes difficult as modern engineering alloys grow more complex, especially with the discovery of high-entropy alloys (HEAs) in 2004. Information about their liquid state behavior is scarce, and potentially quite complex due
[...] Read more.
Understanding the liquid phases and solidification behaviors of multicomponent alloy systems becomes difficult as modern engineering alloys grow more complex, especially with the discovery of high-entropy alloys (HEAs) in 2004. Information about their liquid state behavior is scarce, and potentially quite complex due to the presence of perhaps five or more elements in equimolar ratios. These alloys are showing promise as high strength materials, many composed of solid-solution phases containing equiatomic CoCrCu, which itself does not form a ternary solid solution. Instead, this compound solidifies into highly phase separated regions, and the liquid phase separation that occurs in the alloy also leads to phase separation in systems in which Co, Cr, and Cu are present. The present study demonstrates that in-situ neutron imaging of the liquid phase separation in CoCrCu can be observed. The neutron imaging of the solidification process may resolve questions about phase separation that occurs in these alloys and those that contain Cu. These results show that neutron imaging can be utilized as a characterization technique for solidification research with the potential for imaging the liquid phases of more complex alloys, such as the HEAs which have very little published data about their liquid phases. This imaging technique could potentially allow for observation of immiscible liquid phases becoming miscible at specific temperatures, which cannot be observed with ex-situ analysis of solidified structures. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Characterization of Crystallographic Structures Using Bragg-Edge Neutron Imaging at the Spallation Neutron Source
J. Imaging 2017, 3(4), 65; https://doi.org/10.3390/jimaging3040065
Received: 10 November 2017 / Revised: 4 December 2017 / Accepted: 7 December 2017 / Published: 20 December 2017
Cited by 2 | PDF Full-text (7910 KB) | HTML Full-text | XML Full-text
Abstract
Over the past decade, wavelength-dependent neutron radiography, also known as Bragg-edge imaging, has been employed as a non-destructive bulk characterization method due to its sensitivity to coherent elastic neutron scattering that is associated with crystalline structures. Several analysis approaches have been developed to
[...] Read more.
Over the past decade, wavelength-dependent neutron radiography, also known as Bragg-edge imaging, has been employed as a non-destructive bulk characterization method due to its sensitivity to coherent elastic neutron scattering that is associated with crystalline structures. Several analysis approaches have been developed to quantitatively determine crystalline orientation, lattice strain, and phase distribution. In this study, we report a systematic investigation of the crystal structures of metallic materials (such as selected textureless powder samples and additively manufactured (AM) Inconel 718 samples), using Bragg-edge imaging at the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS). Firstly, we have implemented a phenomenological Gaussian-based fitting in a Python-based computer called iBeatles. Secondly, we have developed a model-based approach to analyze Bragg-edge transmission spectra, which allows quantitative determination of the crystallographic attributes. Moreover, neutron diffraction measurements were carried out to validate the Bragg-edge analytical methods. These results demonstrate that the microstructural complexity (in this case, texture) plays a key role in determining the crystallographic parameters (lattice constant or interplanar spacing), which implies that the Bragg-edge image analysis methods must be carefully selected based on the material structures. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Performance of the Commercial PP/ZnS:Cu and PP/ZnS:Ag Scintillation Screens for Fast Neutron Imaging
J. Imaging 2017, 3(4), 60; https://doi.org/10.3390/jimaging3040060
Received: 31 October 2017 / Revised: 1 December 2017 / Accepted: 7 December 2017 / Published: 10 December 2017
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Abstract
Fast neutron imaging has a great potential as a nondestructive technique for testing large objects. The main factor limiting applications of this technique is detection technology, offering relatively poor spatial resolution of images and low detection efficiency, which results in very long exposure
[...] Read more.
Fast neutron imaging has a great potential as a nondestructive technique for testing large objects. The main factor limiting applications of this technique is detection technology, offering relatively poor spatial resolution of images and low detection efficiency, which results in very long exposure times. Therefore, research on development of scintillators for fast neutron imaging is of high importance. A comparison of the light output, gamma radiation sensitivity and spatial resolution of commercially available scintillator screens composed of PP/ZnS:Cu and PP/ZnS:Ag of different thicknesses are presented. The scintillators were provided by RC Tritec AG company and the test performed at the NECTAR facility located at the FRM II nuclear research reactor. It was shown that light output increases and the spatial resolution decreases with the scintillator thickness. Both compositions of the scintillating material provide similar light output, while the gamma sensitivity of PP/ZnS:Cu is significantly higher as compared to PP/ZnS:Ag-based scintillators. Moreover, we report which factors should be considered when choosing a scintillator and what are the limitations of the investigated types of scintillators. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessArticle Neutron Imaging of Laser Melted SS316 Test Objects with Spatially Resolved Small Angle Neutron Scattering
J. Imaging 2017, 3(4), 58; https://doi.org/10.3390/jimaging3040058
Received: 31 October 2017 / Revised: 30 November 2017 / Accepted: 1 December 2017 / Published: 5 December 2017
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Abstract
A novel neutron far field interferometer is explored for sub-micron porosity detection in laser sintered stainless steel alloy 316 (SS316) test objects. The results shown are images and volumes of the first quantitative neutron dark-field tomography at various autocorrelation lengths, ξ. In
[...] Read more.
A novel neutron far field interferometer is explored for sub-micron porosity detection in laser sintered stainless steel alloy 316 (SS316) test objects. The results shown are images and volumes of the first quantitative neutron dark-field tomography at various autocorrelation lengths, ξ . In this preliminary work, the beam defining slits were adjusted to an uncalibrated opening of 0.5 mm horizontal and 5 cm vertical; the images are blurred along the vertical direction. In spite of the blurred attenuation images, the dark-field images reveal structural information at the micron-scale. The topics explored include: the accessible size range of defects, potentially 338 nm to 4.5 μ m, that can be imaged with the small angle scattering images; the spatial resolution of the attenuation image; the maximum sample dimensions compatible with interferometry optics and neutron attenuation; the procedure for reduction of the raw interferogram images into attenuation, differential phase contrast, and small angle scattering (dark-field) images; and the role of neutron far field interferometry in additive manufacturing to assess sub-micron porosity. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Review

Jump to: Research

Open AccessReview Neutron Imaging at Compact Accelerator-Driven Neutron Sources in Japan
J. Imaging 2018, 4(4), 55; https://doi.org/10.3390/jimaging4040055
Received: 8 November 2017 / Revised: 28 February 2018 / Accepted: 22 March 2018 / Published: 27 March 2018
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Abstract
Neutron imaging has been recognized to be very useful to investigate inside of materials and products that cannot be seen by X-ray. New imaging methods using the pulsed structure of neutron sources based on accelerators has been developed also at compact accelerator-driven neutron
[...] Read more.
Neutron imaging has been recognized to be very useful to investigate inside of materials and products that cannot be seen by X-ray. New imaging methods using the pulsed structure of neutron sources based on accelerators has been developed also at compact accelerator-driven neutron sources and opened new application fields in neutron imaging. The world’s first dedicated imaging instrument at pulsed neutron sources was constructed at J-PARC in Japan owing to the development of such new methods. Then, usefulness of the compact accelerator-driven neutron sources in neutron science was recognized and such facilities were newly constructed in Japan. Now, existing and new sources have been used for neutron imaging. Traditional imaging and newly developed pulsed neutron imaging such as Bragg edge transmission have been applied to various fields by using compact and large neutron facilities. Here, compact accelerator-driven neutron sources used for imaging in Japan are introduced and some of their activities are presented. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessFeature PaperReview Imaging with Polarized Neutrons
J. Imaging 2018, 4(1), 23; https://doi.org/10.3390/jimaging4010023
Received: 1 November 2017 / Revised: 29 December 2017 / Accepted: 11 January 2018 / Published: 16 January 2018
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Abstract
Owing to their zero charge, neutrons are able to pass through thick layers of matter (typically several centimeters) while being sensitive to magnetic fields due to their intrinsic magnetic moment. Therefore, in addition to the conventional attenuation contrast image, the magnetic field inside
[...] Read more.
Owing to their zero charge, neutrons are able to pass through thick layers of matter (typically several centimeters) while being sensitive to magnetic fields due to their intrinsic magnetic moment. Therefore, in addition to the conventional attenuation contrast image, the magnetic field inside and around a sample can be visualized by detecting changes of polarization in a transmitted beam. The method is based on the spatially resolved measurement of the cumulative precession angles of a collimated, polarized, monochromatic neutron beam that traverses a magnetic field or sample. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessReview Neutron Imaging in Cultural Heritage Research at the FRM II Reactor of the Heinz Maier-Leibnitz Center
J. Imaging 2018, 4(1), 22; https://doi.org/10.3390/jimaging4010022
Received: 30 October 2017 / Revised: 6 December 2017 / Accepted: 21 December 2017 / Published: 14 January 2018
Cited by 2 | PDF Full-text (5070 KB) | HTML Full-text | XML Full-text
Abstract
Neutron Imaging is ideally suited for applications in cultural heritage even at small reactors with moderate image resolution. However, recently, high resolution imaging is being increasingly used for advanced studies, especially in paleontology. The special contrast for hydrogen and between neighboring elements in
[...] Read more.
Neutron Imaging is ideally suited for applications in cultural heritage even at small reactors with moderate image resolution. However, recently, high resolution imaging is being increasingly used for advanced studies, especially in paleontology. The special contrast for hydrogen and between neighboring elements in the periodic system allows for new applications that are not accessible for X-rays, like organic material in enclosed containers made of ceramics or metals, fossilized bones in chalk rock or in ferrous “red” beds, and even for animal and hominid teeth. Fission neutrons permit the examination of large samples that otherwise show large attenuation for thermal neutrons. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessReview Deriving Quantitative Crystallographic Information from the Wavelength-Resolved Neutron Transmission Analysis Performed in Imaging Mode
J. Imaging 2018, 4(1), 7; https://doi.org/10.3390/jimaging4010007
Received: 25 November 2017 / Revised: 18 December 2017 / Accepted: 20 December 2017 / Published: 28 December 2017
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Abstract
Current status of Bragg-edge/dip neutron transmission analysis/imaging methods is presented. The method can visualize real-space distributions of bulk crystallographic information in a crystalline material over a large area (~10 cm) with high spatial resolution (~100 μm). Furthermore, by using suitable spectrum analysis methods
[...] Read more.
Current status of Bragg-edge/dip neutron transmission analysis/imaging methods is presented. The method can visualize real-space distributions of bulk crystallographic information in a crystalline material over a large area (~10 cm) with high spatial resolution (~100 μm). Furthermore, by using suitable spectrum analysis methods for wavelength-dependent neutron transmission data, quantitative visualization of the crystallographic information can be achieved. For example, crystallographic texture imaging, crystallite size imaging and crystalline phase imaging with texture/extinction corrections are carried out by the Rietveld-type (wide wavelength bandwidth) profile fitting analysis code, RITS (Rietveld Imaging of Transmission Spectra). By using the single Bragg-edge analysis mode of RITS, evaluations of crystal lattice plane spacing (d-spacing) relating to macro-strain and d-spacing distribution’s FWHM (full width at half maximum) relating to micro-strain can be achieved. Macro-strain tomography is performed by a new conceptual CT (computed tomography) image reconstruction algorithm, the tensor CT method. Crystalline grains and their orientations are visualized by a fast determination method of grain orientation for Bragg-dip neutron transmission spectrum. In this paper, these imaging examples with the spectrum analysis methods and the reliabilities evaluated by optical/electron microscope and X-ray/neutron diffraction, are presented. In addition, the status at compact accelerator driven pulsed neutron sources is also presented. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessReview Small Angle Scattering in Neutron Imaging—A Review
J. Imaging 2017, 3(4), 64; https://doi.org/10.3390/jimaging3040064
Received: 6 November 2017 / Revised: 6 December 2017 / Accepted: 8 December 2017 / Published: 13 December 2017
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Abstract
Conventional neutron imaging utilizes the beam attenuation caused by scattering and absorption through the materials constituting an object in order to investigate its macroscopic inner structure. Small angle scattering has basically no impact on such images under the geometrical conditions applied. Nevertheless, in
[...] Read more.
Conventional neutron imaging utilizes the beam attenuation caused by scattering and absorption through the materials constituting an object in order to investigate its macroscopic inner structure. Small angle scattering has basically no impact on such images under the geometrical conditions applied. Nevertheless, in recent years different experimental methods have been developed in neutron imaging, which enable to not only generate contrast based on neutrons scattered to very small angles, but to map and quantify small angle scattering with the spatial resolution of neutron imaging. This enables neutron imaging to access length scales which are not directly resolved in real space and to investigate bulk structures and processes spanning multiple length scales from centimeters to tens of nanometers. Full article
(This article belongs to the Special Issue Neutron Imaging)
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Open AccessReview Neutron Imaging Facilities in a Global Context
J. Imaging 2017, 3(4), 52; https://doi.org/10.3390/jimaging3040052
Received: 30 October 2017 / Revised: 8 November 2017 / Accepted: 17 November 2017 / Published: 21 November 2017
Cited by 3 | PDF Full-text (2518 KB) | HTML Full-text | XML Full-text
Abstract
Neutron Imaging (NI) has been developed in the last decades from a film-based inspection method for non-destructive observations towards a powerful research tool with many new and competitive methods. The most important technical step forward has been the introduction and optimization of digital
[...] Read more.
Neutron Imaging (NI) has been developed in the last decades from a film-based inspection method for non-destructive observations towards a powerful research tool with many new and competitive methods. The most important technical step forward has been the introduction and optimization of digital imaging detection systems. In this way, direct quantification of the transmission process became possible—the basis for all advanced methods like tomography, phase-contrast imaging and neutron microscopy. Neutron imaging facilities need to be installed at powerful neutron sources (reactors, spallation sources, other accelerator driven systems). High neutron intensity can be used best for either highest spatial, temporal resolution or best image quality. Since the number of such strong sources is decreasing world-wide due to the age of the reactors, the number of NI facilities is limited. There are a few installations with pioneering new concepts and versatile options on the one hand, but also relatively new sources with only limited performance thus far. It will be a challenge to couple the two parts of the community with the aim to install state-of-the-art equipment at the suitable beam ports and develop NI further towards a general research tool. In addition, sources with lower intensity should be equipped with modern installations in order to perform practical work best. Full article
(This article belongs to the Special Issue Neutron Imaging)
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