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- 摘要
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Determination of diffraction time and influence of strip moving speeds on texture measurement using X-ray area detector
摘要： In this study, the two most important factors, diffraction time and the influence of the strip moving speed on diffraction accuracy, are analyzed using a laboratory two-dimensional X-ray diffraction system. The results indicate that 2 s is a diffraction time that satisfies both requirements of detection speed and accuracy. The strip moving speed has a certain influence on the detection accuracy, but the influence of the strip moving speed on the diffraction accuracy can be neglected within a strip moving speed of 0.65 m/s. The measurement of online texture and mechanical properties, combined with the fast texture detection theory and mechanical properties calculation model, can be realized in a steel production factory.
关键词： fast texture detection,diffraction time,X-ray area detector,strip moving speeds
更新于2025-09-23 15:23:52
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Dielectric and Transport Properties of Strontium Modified Calcium Copper Titanate
摘要： The present article provides the detailed study of the effect of strontium on the structural, microstructural, dielectric and electrical characteristics of strontium modified calcium copper titanate (i.e. Ca0.95Sr0.05Cu3Ti4O12, referred as CSCTO further) synthesized by a cost-effective ceramic processing technology. The structural analysis carried out suggests a cubic symmetry in the prepared sample. The dielectric relaxation and electrical conduction mechanism of CSCTO were studied using various powerful spectroscopic tools (i.e dielectric and impedance). Study of temperature dependence of dielectric permittivity exhibits very high (giant) dielectric permittivity (5 (cid:1) 103) and low loss factor at low frequency (1 kHz) at an intermediate temperature (315 (cid:3)C). Structure–properties relationship and conduction mechanism have been studied in a wide frequency (103–106 Hz) and temperature (25–315 (cid:3)C) range. At region of low frequency and high temperatures, there is a dominant role of the interface and Maxwell–Wagner dielectric relaxation mechanism in CSCTO bulk ceramic. The grain, grain boundary and electrode contributes towards the capacitive and resistive property of the sample are discerned from Nyquist plot. The ferroelectric (P–E) loop of the sintered CSCTO bulk sample at room temperature showed a lossy hysteresis loop. These findings further promote the capabilities of CSCTO as a base for supercapacitor.
关键词： X-Ray diffraction,supercapacitor,ferroelectric phase,microstructure,dielectric properties
更新于2025-09-23 15:23:52
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Synthesis of Bismuth Ferrite BiFeO <sub/>3</sub> by solution combustion method
摘要： In this work we describe the synthesis of bismuth ferrite BiFeO3 (BFO) by the method of combustion in solution. Using the techniques of X-ray diffraction (XRD) together with its refinement Rietveld reveals the existence of a distorted rhombohedral perovskite structure (Space group-R3c). The average size of the BFO crystallite was estimated from the half-height width of the X-ray diffraction peaks using the Scherrer’s equation. The morphology of the prepared sample was determined by scanning electron microscopy (SEM) and stoichiometry ratio of BFO was determined by energy dispersive spectroscopy (EDS)
关键词： BFO,X-Ray Diffraction (XRD),Combustion synthesis,Multiferroics
更新于2025-09-23 15:23:52
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Gain and noise in GaAs/AlGaAs avalanche photodiodes with thin multiplication regions
摘要： Avalanche photodiodes based on GaAs/AlGaAs with separated absorption and multiplication regions (SAM-APDs) will be discussed in terms of capacitance, response to light (gain and noise) and time response. The structures have been fabricated by molecular beam epitaxy introducing a δ p layer doped with carbon to separate the multiplication and the absorption regions. The thickness of the latter layer defines the detection efficiency and the time resolution of the structure, which in turn allows tailoring the device for specific scientific applications. Within the multiplication region a periodic modulation of the bandgap is obtained by growing alternating nanometric layers of AlGaAs and GaAs with increasing Al content; this staircase structure enables the tuning of the bandgap and subsequently provides a well-defined charge multiplication. The use of such staircase hetero-junctions enhances electron multiplication and conversely reduces — at least in principle — the impact of the noise associated to hole multiplication, which should result in a decreased overall noise, when compared to p-i-n diodes composed by a single material. The first part of this paper focuses on the electrical characteristics of the grown structure and on the comparison with the simulated behaviour of such devices. In addition, gain and noise measurements, which have been carried out on these devices by utilizing photons from visible light to hard X-rays, will be discussed and will be compared to the results of a nonlocal history-dependent model specifically developed for staircase APDs.
关键词： X-ray detectors,Solid state detectors,Avalanche-induced secondary effects
更新于2025-09-23 15:23:52
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The Percival 2-Megapixel monolithic active pixel imager
摘要： The peak brilliance reached by today’s Free-Electron Laser and Synchrotron light sources requires photon detectors matching their output intensity and other characteristics in order to fully realize the sources’ potential. The Pixellated Energy Resolving CMOS Imager, Versatile And Large (Percival) is a dedicated soft X-ray imager (0.25–1 keV) developed for this purpose by a collaboration of DESY, Rutherford Appleton Laboratory/STFC, Elettra Sincrotrone Trieste, Diamond Light Source, and Pohang Accelerator Laboratory. Following several generations of prototypes, the Percival “P2M” 2-Megapixel imager — a 4.5×5 cm monolithic, stitched sensor with an uninterrupted imaging area of 4×4 cm2 (1408×1484 pixels of 27×27 μm — was produced and has demonstrated basic functionality with a ?rst-light image using visible light. It is currently being brought to full operation in a front-illuminated con?guration. The readout system being commissioned in parallel has been developed speci?cally for this imager which will produce — at full 300 Hz frame rate — data at 20 Gbit/s. A ?rst wafer with eight Percival P2M chips has undergone backthinning to enable soft X-ray detection. It has been diced and chips are currently being wirebonded. We summarize here the P2M system, the project status, and show the P2M sensor’s ?rst response to visible light.
关键词： X-ray detectors,Instrumentation for FEL
更新于2025-09-23 15:23:52
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Current-induced domain wall oscillations in a nanowire imaged by time-resolved photoemission electron microscopy
摘要： We study reversible domain wall motion in half-ring Ni80Fe20 nanowires on a nanosecond (ns) timescale in a truly current-induced pump-probe experiment using an energy filtered, aberration-corrected photoemission electron microscope. The x-ray magnetic circular dichroism signal is probed at different time delays before, during and after the current pulse in a stroboscopic mode with circularly polarized synchrotron radiation in the energy range of the Fe L3-edge (707 eV). We observe lateral domain wall oscillations with a frequency of ～ 0.4 GHz. Comparing the results to a proposed string model, we find that the domain wall oscillations can be described as string-like asymmetric oscillations.
关键词： Synchrotron radiation,Photoemission electron microscopy,X-ray magnetic circular dichroism,Pump-probe mode
更新于2025-09-23 15:23:52
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New heteroleptic iridium(III) nitro complexes derived from fac-[Ir(NO2)3(H2O)3]
摘要： An aqueous solution of fac-[Ir(H2O)3(NO2)3] (1) was utilized as a starting material for preparation of the new heteroleptic iridium complex [Ir(H2O)(bpy)(NO2)3] (2). From alkaline solutions of 2, the salt Na[Ir(OH)(NO2)3(bpy)]·2H2O was isolated and its structure was determined by X-ray structure analysis. Structures of new compounds 2 and 3 as well as the parent complex 1 was characterized using multinuclear magnetic resonance spectroscopy and mass spectrometry. The structures of parent fac-[Ir(H2O)3(NO2)3] and complexes 2 and 3 were probed by employing density functional theory (DFT) calculations.
关键词： Nitrocomplexes,Iridium,DFT,NMR,Aquacomplexes,X-ray structure
更新于2025-09-23 15:23:52
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Development of a new high-speed readout system for SOI pixel detectors
摘要： We are developing a new high-speed readout system for silicon on insulator (SOI) pixel detectors. The SOI detector is a monolithic radiation imaging detector based on a 0.2 μm FD-SOI CMOS process. Previously, we used a Xilinx Virtex-4/5 FPGA readout board for the SOI detector and developed many facilities for this board. However, the Virtex-4/5 FPGA is now obsolete and does not have sufficiently high performance for recent experiments that require more than 1-kHz high-speed imaging with a large number of pixels. Thus, we started to develop a new high-speed readout system using the KC705, which is the evaluation board for the Xilinx Kintex-7 FPGA. We developed a new data acquisition structure that has backward compatibility with the previous environment on this board and implements several functions for practical purposes such as micro Computed Tomography. The transfer speed achieved by the new system is 95.3 fps for a 426k pixel detector in continuous data-taking mode, and 762.5 fps in maximum-speed mode. The details of the new readout system are presented.
关键词： X-ray imaging,SOI,FPGA,DAQ,Pixel detector
更新于2025-09-23 15:23:52
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[IEEE 2018 14th International Conference on Advanced Trends in Radioelecrtronics, Telecommunications and Computer Engineering (TCSET) - Lviv-Slavske, Ukraine (2018.2.20-2018.2.24)] 2018 14th International Conference on Advanced Trends in Radioelecrtronics, Telecommunications and Computer Engineering (TCSET) - Nanoengineering of anisotropic materials for creating the active optical cells with increased energy efficiency
摘要： In this paper the state-of-the-art for exploiting the unique physical and chemical properties of crystalline nanomaterials and their possible applications for creating optical cells with increased energy efficiency are discussed. Using a method of growing crystals from a solution the KDP and TGS nanocrystals were grown in the mesopores of the Al2O3 matrix where the direction of growth was discussed. To investigate the developed nanocomposites the X-ray analysis was used and it showed the predominant crystal orientation of the KDP and TGS in the direction [001] which coincides with the direction of the cylindrical pores. Thus, the possibility of growing of the KDP and TGS nanocrystals in the mesopores of the Al2O3 matrix was developed and provides the prospect of creating optical cells with increased energy efficiency.
关键词： X-ray analysis,anisotropic materials,crystalline nanocomposites,nanoporous matrices,Al2O3,nanofiller KDP and TGS
更新于2025-09-23 15:23:52
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Differentiable Monte Carlo ray tracing through edge sampling
摘要： Gradient-based methods are becoming increasingly important for computer graphics, machine learning, and computer vision. The ability to compute gradients is crucial to optimization, inverse problems, and deep learning. In rendering, the gradient is required with respect to variables such as camera parameters, light sources, scene geometry, or material appearance. However, computing the gradient of rendering is challenging because the rendering integral includes visibility terms that are not differentiable. Previous work on differentiable rendering has focused on approximate solutions. They often do not handle secondary effects such as shadows or global illumination, or they do not provide the gradient with respect to variables other than pixel coordinates. We introduce a general-purpose differentiable ray tracer, which, to our knowledge, is the first comprehensive solution that is able to compute derivatives of scalar functions over a rendered image with respect to arbitrary scene parameters such as camera pose, scene geometry, materials, and lighting parameters. The key to our method is a novel edge sampling algorithm that directly samples the Dirac delta functions introduced by the derivatives of the discontinuous integrand. We also develop efficient importance sampling methods based on spatial hierarchies. Our method can generate gradients in times running from seconds to minutes depending on scene complexity and desired precision. We interface our differentiable ray tracer with the deep learning library PyTorch and show prototype applications in inverse rendering and the generation of adversarial examples for neural networks.
关键词： ray tracing,differentiable programming,inverse rendering
更新于2025-09-23 15:23:52