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266 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I12-JEEP: Joint Engineering, Environmental and Processing	A scalable neural network architecture for self-supervised tomographic image reconstruction Hongyang Dong , Simon D. M. Jacques , Winfred Kockelmann , Stephen W. T. Price , Robert Emberson , Dorota Matras , Yaroslav I. Odarchenko , Vesna Middelkoop , Athanasios Giokaris , Olof Gutowski , Ann-Christin Dippel , Martin Von Zimmermann , Andrew M. Beale , Keith T. Butler , Antonios Vamvakeros Digital Discovery 2 DOI: 10.1039/D2DD00105E Open Access Show Abstract ▼ Abstract: We present a lightweight and scalable artificial neural network architecture which is used to reconstruct a tomographic image from a given sinogram. A self-supervised learning approach is used where the network iteratively generates an image that is then converted into a sinogram using the Radon transform; this new sinogram is then compared with the sinogram from the experimental dataset using a combined mean absolute error and structural similarity index measure loss function to update the weights of the network accordingly. We demonstrate that the network is able to reconstruct images that are larger than 1024 × 1024. Furthermore, it is shown that the new network is able to reconstruct images of higher quality than conventional reconstruction algorithms, such as the filtered back projection and iterative algorithms (SART, SIRT, CGLS), when sinograms with angular undersampling are used. The network is tested with simulated data as well as experimental synchrotron X-ray micro-tomography and X-ray diffraction computed tomography data.	Jun 2023
I22-Small angle scattering & Diffraction	"Sounding" out crystal nuclei - A mathematical-physical and experimental investigation Megan J. Povey , Rammile Ettelaie , Ken Lewtas , Andy Price , Xiaojun Lai , Fei Sheng The Journal Of Chemical Physics 158 DOI: 10.1063/5.0139811 Diamond Proposal Number(s): [20481, 27656] Open Access Show Abstract ▼ Abstract: We outline techniques for the control and measurement of the nucleation of crystalline material. SAXS/WAXS XRD measurements are presented that demonstrate the impact of low power, continuous, non-cavitational ultrasound on the nucleation and crystallisation of a wax; n-eicosane dissolved in heptane/toluene solvent. A mathematical-physical approach based on rectification of heat and mass transport by such a low power oscillating pressure field is outlined and it is suggested that this approach be combined with dissipative particle dynamics (DPD) computational modelling to develop a predictive method capable of modelling the impact of low power oscillating pressure fields (acoustics and ultrasonics) on a wide range of nucleating systems. Combining ultrasound pitch and catch speed of sound measurements with low power harmonically oscillating pressure fields to monitor and control nucleation presents the prospect of entirely new industrially significant methods of process control in crystallisation. It also offers new insights into nucleation processes in general. However, for the acoustic control technique to be applied widely, further theoretical and modelling work will be necessary since at present, we are unable to predict the precise effect of low power ultrasound in any given situation.	May 2023
I22-Small angle scattering & Diffraction	A machine learning model for textured X-ray scattering and diffraction image denoising Zhongzheng Zhou , Chun Li , Xiaoxue Bi , Chenglong Zhang , Yingke Huang , Jian Zhuang , Wenqiang Hua , Zheng Dong , Lina Zhao , Yi Zhang , Yuhui Dong Npj Computational Materials 9 DOI: 10.1038/s41524-023-01011-w Open Access Show Abstract ▼ Abstract: With the advancements in instrumentations of next-generation synchrotron light sources, methodologies for small-angle X-ray scattering (SAXS)/wide-angle X-ray diffraction (WAXD) experiments have dramatically evolved. Such experiments have developed into dynamic and multiscale in situ characterizations, leaving prolonged exposure time as well as radiation-induced damage a serious concern. However, reduction on exposure time or dose may result in noisier images with a lower signal-to-noise ratio, requiring powerful denoising mechanisms for physical information retrieval. Here, we tackle the problem from an algorithmic perspective by proposing a small yet effective machine-learning model for experimental SAXS/WAXD image denoising, allowing more redundancy for exposure time or dose reduction. Compared with classic models developed for natural image scenarios, our model provides a bespoke denoising solution, demonstrating superior performance on highly textured SAXS/WAXD images. The model is versatile and can be applied to denoising in other synchrotron imaging experiments when data volume and image complexity is concerned.	Apr 2023
I13-1-Coherence	Near-field multi-slice ptychography: quantitative phase imaging of optically thick samples with visible light and X-rays Ziyang Hu , Yiqian Zhang , Peng Li , Darren Batey , Andrew Maiden Optics Express 31 DOI: 10.1364/OE.487002 Diamond Proposal Number(s): [30097] Open Access Show Abstract ▼ Abstract: Ptychography is a form of lens-free coherent diffractive imaging now used extensively in electron and synchrotron-based X-ray microscopy. In its near-field implementation, it offers a route to quantitative phase imaging at an accuracy and resolution competitive with holography, with the added advantages of extended field of view and blind deconvolution of the illumination beam profile from the sample image. In this paper we show how near-field ptychography can be combined with a multi-slice model, adding to this list of advantages the unique ability to recover high-resolution phase images of larger samples, whose thickness places them beyond the depth of field of alternative methods.	Apr 2023
I22-Small angle scattering & Diffraction	Ultra-low oxygen, liquid sample cell for in situ synchrotron-based small-wide angle scattering (SAXS-WAXS) M. Hassan Sk , S. Agrawal , M. Woolley , S. M. Clarke , A. Osundare , D. Craske , Robert Lindsay , Andrew J. Smith , T. Snow , T. Zinn , N. Terrill Review Of Scientific Instruments 94 DOI: 10.1063/5.0146013 Diamond Proposal Number(s): [23699, 28693, 32669] Open Access Show Abstract ▼ Abstract: Here, we report the design and successful implementation of an ultra-low oxygen sample cell for use on the SAXS-WAXS (small-wide angle x-ray scattering) beamline I22 at DIAMOND. The rigorous exclusion of oxygen is found to require double jacketing with purge gas throughout the entire system, pipework, pumps, and the sample cell itself. This particularly includes a “double-window” arrangement at the sample location to accommodate the very tight geometrical restrictions of the sample position. The in situ cell design also requires the additional complexity of heating the sample/solution and real-time electrochemical measurements. We demonstrate the successful implementation of this arrangement with real-time in situ characterization of an iron foil corrosion evolving under the “sweet-scale environment,” very anoxic conditions common, in particular, commercial situations. The formation of iron carbonate, siderite, rather than iron oxide, indicates that our system is oxygen free down very low levels (<35 ppb at 80 °C).	Apr 2023
I12-JEEP: Joint Engineering, Environmental and Processing	Application of a new method for accurate determination of α and β texture in Ti-6Al-4 V from synchrotron diffraction intensities Christopher S. Daniel , Xiaohan Zeng , Stefan Michalik , Simon A. Hunt , Joao Quinta Da Fonseca Materials Characterization DOI: 10.1016/j.matchar.2023.112769 Diamond Proposal Number(s): [25682] Open Access Show Abstract ▼ Abstract: The crystallographic texture development during processing of dual-phase Ti alloys like Ti-6Al-4 V is of fundamental technological importance. However, measuring texture in both phases in these materials is a significant challenge because of the spatial inhomogeneity of the texture and low volume fraction of the minority β-phase at room temperature. Here we demonstrate how synchrotron X-ray diffraction can be used to overcome these difficulties and measure texture and texture variation in hot-rolled samples in a reproducible manner. The texture in hot-rolled Ti-64 was calculated from 2D synchrotron diffraction patterns obtained along different directions. The data was analysed using MAUD, which is based on Rietveld refinement of the diffracted intensities, and using a Fourier series based analysis method, that extracts intensities directly from the 2D diffraction patterns, and then uses the open-source software MTEX to fit an orientation distribution function (ODF). By comparing the results with faithful EBSD measurements, we show that the Fourier series method produces much more accurate texture measurements, especially for the minority β-phase. We also show that a minimum of 2, and preferably 3, different measurement orientations are needed to fully represent the texture. This implies that measurements of texture which rely on diffraction data from a single sample orientation, like in fast in-situ studies or spatially resolved measurements, can only provide qualitative information and must be interpreted with care.	Mar 2023
	Angular X-ray transmission measurements of gold absorption gratings: comparison of different laboratory X-ray sources Gideon Chinamatira , Kudakwashe Jakata , Bhekumusa Mathe , Josephine Gutekunst , Anton Du Plessis 12th Conference on Industrial Computed Tomography Show Abstract ▼ Abstract: Over the past few years, numerous advances have been made in X-ray imaging technology. X-ray imaging plays an important role in the non-destructive exploration of the internal structures of objects for research, medical and industrial applications. When X-rays are used in computed tomography (CT), the differences in density of various components of a specimen result in different degrees of absorption of the X-rays and are ultimately responsible for image formation and image contrast. However, in some situations, this contrast is not sufficient for the sample, e.g. in the case of fossils embedded in rock, there are often situations where the fossil and rock have similar grey values. Poor contrast causes the loss of valuable detail and makes further image processing steps such as segmentation challenging. There is a continuous need to improve and develop new image acquisition techniques with the goal to improve the quality of the obtained CT data. Computed tomography techniques have been extended to phase contrast imaging in recent years using the principle of Talbot-Lau interferometers. Initially performed in synchrotron facilities the method was extended to work with incoherent polychromatic X-ray sources by introducing a source grating into the setup and therefore reducing the requirements on the spatial coherence of the source significantly. In this work, we report on the experimental characterization of gold absorption gratings used in such a laboratory-based cone-beam phase contrast setup. The gold gratings are characterized by Angular X-ray Transmission using different laboratory X-ray sources, providing insights not only into the grating feature sizes but also validating the suitability of the available laboratory source for phase contrast imaging. This work is the first step in a project implementing phase contrast X-ray imaging in laboratory setups in South Africa.	Feb 2023
I13-1-Coherence	Fabrication of high-aspect ratio nanogratings for phase-based X-ray imaging Martyna Michalska , Alessandro Rossi , Gašper Kokot , Callum M. Macdonald , Silvia Cipiccia , Peter R. T. Munro , Alessandro Olivo , Ioannis Papakonstantinou Advanced Functional Materials 05 DOI: 10.1002/adfm.202212660 Diamond Proposal Number(s): [28831] Open Access Show Abstract ▼ Abstract: Diffractive optical elements such as periodic gratings are fundamental devices in X-ray imaging – a technique that medical, material science, and security scans rely upon. Fabrication of such structures with high aspect ratios at the nanoscale creates opportunities to further advance such applications, especially in terms of relaxing X-ray source coherence requirements. This is because typical grating-based X-ray phase imaging techniques (e.g., Talbot self-imaging) require a coherence length of at least one grating period and ideally longer. In this paper, the fabrication challenges in achieving high-aspect ratio nanogratings filled with gold are addressed by a combination of laser interference and nanoimprint lithography, physical vapor deposition, metal assisted chemical etching (MACE), and electroplating. This relatively simple and cost-efficient approach is unlocked by an innovative post-MACE drying step with hexamethyldisilazane, which effectively minimizes the stiction of the nanostructures. The theoretical limits of the approach are discussed and, experimentally, X-ray nanogratings with aspect ratios >40 are demonstrated. Finally, their excellent diffractive abilities are shown when exposed to a hard (12.2 keV) monochromatic X-ray beam at a synchrotron facility, and thus potential applicability in phase-based X-ray imaging.	Jan 2023
B07-B-Versatile Soft X-ray beamline: High Throughput	UHV XPS and NEXAFS opportunities at VerSoX B07-B, diamond light source Pilar Ferrer , David C. Grinter , Georg Held SPIE Photonex DOI: 10.1117/12.2647577 Show Abstract ▼ Abstract: We present a new beamline for Versatile Soft X-ray Spectroscopy at Diamond Light Source, VerSoX B07-B, with a medium X-rays flux in the photon energy range 45-2200 eV. B07-B has two endstations permitting studies of a wide range of interfaces and materials. ES-2 enables high-throughput NEXAFS (Near-Edge X-ray Absorption Fine Spectroscopy) under ambient-pressure conditions, ES-1 is dedicated to high-throughput X-ray Photoelectron Spectroscopy (XPS) and in ultra-high vacuum (UHV). ES-1 is fully motorised and automated; it is equipped with fast entry lock, rotary distribution, sample storage and two sample preparation chambers for standard UHV sample preparation and characterisation.	Jan 2023
E02-JEM ARM 300CF	Versatile domain mapping of scanning electron nanobeam diffraction datasets utilising variational autoencoders A. Bridger , W. I. F. David , T. J. Wood , M. Danaie , K. T. Butler Npj Computational Materials 9 DOI: 10.1038/s41524-022-00960-y Diamond Proposal Number(s): [19064, 28749] Open Access Show Abstract ▼ Abstract: Characterisation of structure across the nanometre scale is key to bridging the gap between the local atomic environment and macro-scale and can be achieved by means of scanning electron nanobeam diffraction (SEND). As a technique, SEND allows for a broad range of samples, due to being relatively tolerant of specimen thickness with low electron dosage. This, coupled with the capacity for automation of data collection over wide areas, allows for statistically representative probing of the microstructure. This paper outlines a versatile, data-driven approach for producing domain maps, and a statistical approach for assessing their applicability. The workflow utilises a Variational AutoEncoder to identify the sources of variance in the diffraction signal, and this, in combination with clustering techniques, is used to produce domain maps. This approach is agnostic to domain crystallinity, requires no prior knowledge of crystal structure, and does not require simulation of a library of expected diffraction patterns.	Jan 2023

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