X-ray fluorescence microtomography based on polycapillary-focused X-rays from laboratory source

X-ray fluorescence microtomography(μXFCT)is a nondestructive analytical technique and has been widely used to nondestructively detect and quantify the elemental composition and distributions in samples. Usually, synchrotron radiation X-rays are used for μXFCT, due to its high flux density. In this paper, a laboratory-sourcebased μXFCT system was developed, in which a polycapillary lens is employed to focus the X-ray beam and improve the flux density. The maximum likelihood expectation maximization algorithm was used to reconstruct the computed tomography slices at a limited number of projections. The experimental results demonstrated that the developed system could reveal the elemental distribution inside the test sample, with an elemental sensitivity of 1000 ppm.     

A synchrotron radiation microprobe for X-ray fluorescence and microtomography at ELETTRA

A synchrotron radiation microscope based on X-ray fluorescence and computed microtomography for advanced applications in biomedicine, environmental sciences, geology and materials science is described. This microscope will utilize the radiation produced by a bending magnet of ELETTRA, the third-generation, high-brilliance synchrotron radiation facility being built in Trieste. Various wide-band-pass mirror systems operating in an energy range between 7 and 17 keV have been designed. For example, multilayer-coated mirrors in the Kirkpatrick-Baez configuration can produce a spatial resolution of 1 μm² for a flux in excess of 10⁸ photons per second on the sample (E = 12 keV, E/ΔE = 10). This X-ray microprobe will allow micrometric mapping of trace and minor elements and computed tomographic imaging with high resolution, opening a new realm of experiments in different fields of science, such as in vivo elemental scanning and microtomography of cultured cells, analysis of single atmospheric particulates, analysis of cosmic debris collected from the stratosphere and antarctic ice, etc. The preliminary design of the beam line and the performance of the microprobe are discussed.     

Internal elemental imaging by scanning X-ray fluorescence microtomography at the hard X-ray microprobe beamline of the SSRF: Preliminary experimental results

Synchrotron-based X-ray micro-fluorescence (μ-SXRF) is a non-destructive analytical technique and has been widely used to detect and quantify the elemental composition of samples in their natural state. To determine the internal elemental distributions within samples, X-ray fluorescence microtomography has been developed based on the hard X-ray microprobe at beamline BL15U1 of the Shanghai Synchrotron Radiation Facility (SSRF) in Shanghai, China. This technique was applied to image the cross-sectional distributions of multiple elements within a single human hair, and its validity was evaluated by comparing the results with the elemental maps of a thin hair section obtained using the well-established μ-SXRF mapping method. Elemental images of S, Ca, Mn, Fe, Cu, and Zn within a virtual slice of the hair were reconstructed after the tomographic measurements. The tomographic images of heavy elements like Fe, Cu, and Zn were found to be in good agreement with the corresponding μ-SXRF maps. Light elements, such as S, however, represented different patterns due to non-negligible self-absorption in the sample, and sophisticated correction algorithms accounting for such effects are required for obtaining qualitatively and quantitatively more accurate images. Compared to μ-SXRF mapping, X-ray fluorescence microtomography reduces the sample preparation requirements and has been demonstrated in this work as being a more ideal and effective imaging modality to non-destructively mapping out the internal distribution of heavy elements within samples at the micrometer scale at the SSRF.     

Effects of internal scattering on X-ray microtomography imagereconstruction

A computer simulation is used to study the problem of internal scattering for targets that are imaged using X-ray microtomography. A strategy is outlined for selecting X-ray energy and image resolution based on properties of the material being imaged. The X-ray scanning process is simulated by applying a Monte Carlo technique to a modeled target that emulates the material properties of a microelectronic device. The X-ray photons are subject to photoelectric absorption, Rayleigh scattering, and Compton scattering. The simulation applies a method of high-resolution image reconstruction based on discrete Fourier transforms. Examples of reconstructed images that have 0.5-μm spatial resolution are shown for images of simulated lead and aluminum targets     

全反射X射线荧光分析

综述了全反射X射线荧光分析技术的基本原理,装置及特点,介绍了全射X射线荧光分析技术的应用及其前景。     

基于采集卡的高分辨X射线检测系统

针对印刷电路板中BGA器件焊点缺陷检测数字化成像问题,设计了一套应用Matrox公司的MeteorII-CameraLink型号采集卡及HAWK-160XI型X-射线源和UNIQ-1800 CCD相机组成的高分辨率X-射线缺陷检测系统。经试验测试最佳放大率下系统分辨率17 lp/mm,缺陷分析精度最小分辨率达到0.03 mm,并给出测试采集效果图。     

X-ray fluorescence in investigations of archaeological finds

X-ray fluorescence can be successfully used for analysing the elemental composition of the superficial layers of a measured object, especially for investigating surface coatings, deposits of adventitious materials on the surface, etc. An energy dispersive version of X-ray fluorescence analysis is used in our investigations for analysing various historic objects, art works and archaeological finds. Examples of the application of X-ray fluorescence to various archaeological finds from excavations in the Czech Republic are presented - shards of ancient glazed ceramics, moulds for casting metal products, the remains of a human finger with traces of brass, probably from a ring, etc.     

X-ray microtomography analysis and Molecular Dynamics calculations to understand the dynamic damage process in metals

Dynamic ductile damage has been created by a laser driven shock. The study of these processes consists of predicting it and analysing spatial distributions of pores observed in the target. The challenge is to use the Molecular Dynamics to calculate the propagation of shock waves in ultra thin sheets of metal as well as to compare results with ESRF’s X-ray microtomography.     

Atomic data for accelerator-based X-ray fluorescence spectroscopy

For use in basic and applied research, an atomic data library with atomic-emission and -structure data was developed by using an EC 1055/56 computer facility. The data files contain X-ray transition data, orbital data. Auger-transition data and photon mass attenuation coefficients for all elements up to uranium. The data are stored in a generalized format that permits suitable data handling considering the features of atomic data sets. The data are available either in book form, computer listings or as files on magnetic tape. Computer codes for calculation of radiative and nonradiative transition probabilities have been developed and successfully tested for various configurations of neutral and ionized atoms.     

USB总线技术在现场X荧光分析仪中的应用

从对USB总线技术及GPS技术应用于现场X荧光分析仪的可行性进行了分析,并重点介绍了USB总线及多道脉冲分析器硬件设计和下位机固件设计。简要介绍了设备驱动程序设计以及上位机软件设计。     

High-resolution boron dilution measurements using laser induced fluorescence (LIF)

The application of the laser induced fluorescence technique to the study of liquid mixing in the downcomer of a pressurized water reactor is presented. The scenario is that of a boron dilution event, in which a deborated slug is set in motion by the actuation of a reactor coolant pump. A separate effects test facility, built with transparent plexiglas, is used to conduct optical measurements of the slug mixing along its path to the core. The optical assembly is described and the conditions for the implementation of laser induced fluorescence as a quantitative measurement technique are discussed. Results from a slug injection experiment are shown which demonstrate the high-resolution capabilities of this procedure as applied to the study of liquid mixing in the complex geometry of a reactor vessel downcomer.     

High-resolution pixelated CdZnTe detector prototype system for solar hard X-ray imager

A multichannel low-noise electronic prototype system was designed for a pixelated CdZnTe detector. This system is the result of preliminary work on a solar hard X-ray imager, which is one of the three payloads for future solar observations satellite-Advanced Space-based Solar Observatory(ASO-S). A new charge-sensitive amplifier application-specific integrated circuit, VATA450.3, with an on-chip analog-to-digital converter, is used to read out 8×8 anode pixel signals. Two CdZnTe detectors with a thickness of 2 mm and 5 mm were tested. The 2-mm-thick detector achieved energy resolution better than 5%(fullwidth at half-maximum, FWHM) at 59.5 keV, and the 5-mm-thick detector had better resolution than 1.2%(FWHM) at 662 keV. The design and test results of the prototype system are discussed in this paper.     

便携式野外X荧光分析仪的PWM电源设计

便携式野外X荧光分析仪是一种能够在野外现场快速测定As,Cu等重要元素的新型核地质仪器,结合该仪器电源部分的研制,较全面地阐述了野外仪器PWM电源设计中的几个要素。     

Estimating particle size effects in X-ray fluorescence spectrometry

The influence of size of particles on the X-ray fluorescence intensity for powdered substances with different sized particles is estimated, based on a simple modification of the Berry-Furuta-Rhodes formulae. Analytical expressions are obtained for the model of a powder substance consisting of particles of various sizes distributed randomly in the sample volume. The results of calculations by these expressions agree fairly well with experimental data for binary powder mixtures. The particle size effect on X-ray fluorescence for the powders presented is considerably more than one could be predicted by the models proposed earlier.     

Techniques for depth heterogeneity identification in X-ray fluorescence

Two methods enabling depth heterogeneity to be recognized and taken into account in quantitative analysis have been elaborated and then applied to various samples. The first method involves predicting the Kα/Kβ (or L lines) ratios for all identified elements. The second method is based on comparing the spectra measured on different geometric arrangements. In particular, sample tilting makes identification of depth heterogeneities possible. If the sample is heterogeneous, the heights of some peaks in the X-ray spectra change according to the depth distribution of the corresponding elements. Monte Carlo simulations with the MCNP4C2 code can be used to predict these changes and interpret the experimental results.