Materials identification using a small-scale pixellated x-ray diffraction system

O’Flynn, Daniel; Crews, Chiaki; Drakos, Ireneos; Christodoulou, Christiana; Wilson, Matthew D.; Veale, Matthew C.; Seller, P.; Speller, Robert

doi:10.1088/0022-3727/49/17/175304

Cited by 19 publications

(13 citation statements)

References 27 publications

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“…The two Debye-Scherrer ring sections seen for caffeine represent constructive interference of X-rays in the 22-24.5 keV energy range from caffeine d-spacings of 7.53 Å, 7.40 Å, 3.37 Å and 3.30 Å. The first two and latter two spacings are not individually resolved [8]. Rings are seen due to the fact that the caffeine sample was a fine powder, and as such the primary X-ray beam was incident upon a large number of crystallites with random orientations about the incident beam axis.…”

Section: Resultsmentioning

confidence: 92%

“…The spatial resolution afforded by the detector pixels enables angular scatter information to be preserved without the need for collimation of the scattered beam -this is true provided the sample thickness remains of the order of several millimetres [16] -and as such the counting statistics of the system are greatly improved with respect to previous EDXRD systems based on a single-element detector. Additionally, further information on the grain size present in the sample is preserved with the diffraction image, as can be seen by comparing the Debye-Scherrer rings in fine grain caffeine and distinct spots in large grain hexamine [7,8]. The peak widths for this diffraction technique are wider than those in diffractometer scans.…”

Section: Resultsmentioning

confidence: 99%

“…A broad X-ray spectrum is incident upon the sample, and an energy-resolving detector is used to isolate energy windows and produce XRD data. Recently, a pixellated diffraction (PixD) method which combines features of both ADXRD and EDXRD was developed, allowing the use of a polychromatic X-ray source and uncollimated scattered X-rays to be detected, giving a large increase in counting efficiency [7,8]. This technique utilised the pixellated, energy-resolving HEXITEC detector [9][10][11], which enabled both spatial and spectral diffraction information to be preserved simultaneously.…”

Section: Introductionmentioning

confidence: 99%

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Energy-windowed, pixellated X-ray diffraction using the Pixirad CdTe detector

et al. 2017

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X-ray diffraction (XRD) is a powerful tool for material identification. In order to interpret XRD data, knowledge is required of the scattering angles and energies of X-rays which interact with the sample. By using a pixellated, energy-resolving detector, this knowledge can be gained when using a spectrum of unfiltered X-rays, and without the need to collimate the scattered radiation. Here we present results of XRD measurements taken with the Pixirad detector and a laboratorybased X-ray source. The cadmium telluride sensor allows energy windows to be selected, and the 62 μm pixel pitch enables accurate spatial information to be preserved for XRD measurements, in addition to the ability to take high resolution radiographic images. Diffraction data are presented for a variety of samples to demonstrate the capability of the technique for materials discrimination in laboratory, security and pharmaceutical environments. Distinct diffraction patterns were obtained, from which details on the molecular structures of the items under study were determined.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Energy-windowed, pixellated X-ray diffraction using the Pixirad CdTe detector

et al. 2017

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“…Significantly higher X-ray energies are required (i.e. an order of magnitude increase in photon energy over the legacy 8 keV Cu Kα [7]) for transmission mode diffraction for highly absorbing and or extended thickness samples [7][8][9]. Conventional fan beam tomography has provided diffracted flux measurements [5,[9][10][11] to demonstrate spatially-resolved material specific profiles.…”

mentioning

confidence: 99%

Combined X-ray diffraction and absorption tomography using a conical shell beam

Shevchuk¹,

Evans²,

Dicken³

et al. 2019

Opt. Express

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We combine diffraction and absorption tomography by raster scanning samples through a hollow cone of pseudo monochromatic X-rays with a mean energy of 58.4 keV. A single image intensifier takes 90x90 (x,y) snapshots during the scan. We demonstrate a proofof-principle of our technique using a heterogeneous three-dimensional (x,y,z) phantom (90x90x170 mm 3 ) comprised of different material phases, i.e., copper and sodium chlorate. Each snapshot enables the simultaneous measurement of absorption contrast and diffracted flux. The axial resolution was ~1 mm along the (x,y) orthogonal scan directions and ~7 mm along the z-axis. The tomosynthesis of diffracted flux measurements enable the calculation of d-spacing values with ~0.1 Å full width at half maximum (FWHM) at ~2 Å. Thus the identified materials may be color-coded in the absorption optical sections. Characterization of specific material phases is of particular interest in security screening for the identification of narcotics and a wide range of homemade explosives concealed within complex "everyday objects." Other potential application areas include process control and biological imaging. IntroductionRadiographic imaging and the structural analysis of materials using X-rays developed disparately soon after the discovery of X-rays in 1895 [1]. The former has evolved from simple planar imaging into sophisticated tomographic methods [2,3], while the latter formed the basis of X-ray crystallography. Each approach demands quite different spatiotemporal collection and sensing requirements [4,5]. In general, incident X-rays composing a spatial image propagate along a linear path from the source to the detector and do not interact with the materials under inspection. However, the spectroscopic analysis of the transmitted X-rays may provide some useful materials discrimination information [6]. Ultimately, such approaches are limited fundamentally and cannot provide structural or 'molecular resolution' analysis. In contrast, determination of the atomic and molecular structure of crystalline/polycrystalline materials requires analysis of coherently scattered or diffracted Xrays from a sample. The relatively low energy of the interrogating radiation used in laboratory X-ray diffraction (XRD) limits penetration into the sample to near the incident surface. Significantly higher X-ray energies are required (i.e. an order of magnitude increase in photon energy over the legacy 8 keV Cu Kα [7]) for transmission mode diffraction for highly absorbing and or extended thickness samples [7][8][9]. Conventional fan beam tomography has provided diffracted flux measurements [5,[9][10][11] to demonstrate spatially-resolved material specific profiles. Novel compressive tomography promises further reductions in scan times and exposure [12][13][14]. The common problem confronting all volumetric XRD scanning/imaging methods is the production and measurement of sufficient diffracted flux or signal photons to provide the desired scan speed at application dependent energies. These consideration...

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“…This property coupled with their interaction on an atomic and molecular scale to produce crystallographic, structurally dependent scattering has fuelled new scientific discoveries and instrumentation for well over a century. For example, X-ray based probes have proliferated into a wealth of important non-destructive imaging modalities capitalising upon different X-ray interaction mechanisms including; X-ray spectroscopy, 2 X-ray diffraction (XRD), [3][4][5][6][7] coherent scattering, 8 and phase contrast, 9 . Many applications would benefit from the information provided by these probes attributed to material phases distributed within an inspection volume.…”

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confidence: 99%

Dual conical shell illumination for volumetric high-energy X-ray diffraction imaging

Dicken

Spence

Rogers

et al. 2018

Analyst

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To retrieve crystallographic information from extended sample volumes requires a high-energy probe. The use of X-rays to combine imaging with materials characterisation is well-established. However, if fundamental crystallographic parameters are required, then the collection and analysis of X-rays diffracted by the inspected samples are prerequisites. We present a new X-ray diffraction imaging architecture, which in comparison with previous depth-resolving hollow beam techniques requires significantly less X-ray power or alternatively supports significantly increased scanning speeds. Our conceptual configuration employs a pair of conical shell X-ray beams derived from a single point source to illuminate extended samples. Diffracted flux measurements would then be obtained using a pair of energy resolving point detectors. This dual beam configuration is tested using a single X-ray beam set-up employing a dual scan. The use of commercial off-the-shelf low-cost components has the potential to provide rapid and cost-effective performance in areas including industrial process control, medical imaging and explosives detection.

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Materials identification using a small-scale pixellated x-ray diffraction system

Cited by 19 publications

References 27 publications

Energy-windowed, pixellated X-ray diffraction using the Pixirad CdTe detector

Energy-windowed, pixellated X-ray diffraction using the Pixirad CdTe detector

Combined X-ray diffraction and absorption tomography using a conical shell beam

Dual conical shell illumination for volumetric high-energy X-ray diffraction imaging

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