一种毛细管聚焦的便携式微束X射线荧光谱仪

基于毛细管X光透镜技术的便携式能量色散X射线荧光分析因其无损分析等优点成为分析文物样品的有利工具。但由于文物样品的表面不平整或弧度以及毛细管X光透镜聚焦X射线的特点，导致在测量过程中样品测量点与毛细管X光透镜出端之间的距离产生变化，引起照射样品的X射线束斑大小发生改变，从而影响测量结果的准确性和元素区域扫描的分辨率。介绍了本实验室自行研发的一种新型便携式微束X射线荧光谱仪，此谱仪主要是由SDD X射线探测器、30 W低功率X射线管、毛细管X光透镜、CCD和一个新型闭环控制系统构成。该闭环控制系统是在激光位移传感器能够精确控制样品测量点到毛细管X光透镜出端距离的基础上，结合LabVIEW语言环境下开发的计算机控制程序以及步进电机、样品台等器件组成。基于此系统，该实验室研发的便携式微束X射线荧光谱仪在测量过程中可以时刻保证照射样品的X射线光斑大小固定不变。同时，该谱仪还可以通过调整样品测量点到透镜出端的距离来选择不同尺寸的X射线照射光斑。为了验证设备的可行性，使用该便携式微束X射线荧光谱仪在激活激光位移传感器和关闭激光位移传感器两种情况下测量了一块表面不平整古陶瓷样品釉彩层中K，Ca，Zn和Fe等元素的含量及分布，并将测量结果进行了对比。结果显示，在激活激光位移传感器的情况下测得的样品微区元素含量与真实值较接近，扫描区域元素分布图的分辨率更好，表明本谱仪基于激光位移传感器开发的自动调整样品测量点到透镜出口端距离的闭环控制系统能有效的减少由于样品表面不平整或弧度带来的测量误差，弥补了现有微束X射线荧光谱仪在此方面的不足。因此，本便携式微束X射线荧光谱仪在无损分析检测文物方面具有潜在的应用前景。     

Polycapillary X-ray lens for the secondary focusing Beijing synchrotron radiation source

According to intensity distribution of the synchrotron radiation source focused by a toroidal mirror at the Beijing synchrotron radiation biological macromolecule station, theoretical modeling of the Beijing synchrotron radiation source is developed for capillary optics. Using this theoretical modeling, the influences of the configuration curve of the polycapillary X-ray lens on transmission efficiency and working distance are analyzed. The experimental results of the transmission efficiency and working distance at the biological macromolecule station are in good agreement with the theoretical results.     

Scanning X-ray microanalysis of bottom sediments using synchrotron radiation from the BINP VEPP-3 storage ring

Combining the features of synchrotron radiation (low angular divergence and continuous spectrum, natural polarization, and high intensity) with the use of modern X-ray optics (polycapillary lenses) and registering devices results in a new quality of analysis: measuring picogram concentrations of a broad set of elements with micron spatial resolution. Using a dedicated experimental station and developed methodologies, numerous scanning microanalyses of bottom sediments is performed to obtain a time series of geochemical indicators of paleoclimate in the Central Asian region. The detection limit under optimum conditions is 5 × 10^?5% with a spatial resolution of ～100 μm.     

Characterization of homemade x‐ray polycapillaries

The possibilities of performing non‐destructive elemental microanalysis with synchrotron radiation by means of homemade polycapillary optics are described. Using fiber glass technology, monolithic polycapillary half‐lenses were made by drawing packages of glass capillaries at high temperature in a heating furnace. The performance of polycapillary half‐lenses with different geometries was evaluated. A gold knife‐edge scanned at the output of the lenses was used to determine the spot size at different distances. Measurements of photon flux impinging on the entrance end of the lenses and photon flux leaving the lenses were used to obtain the transmission efficiency. The polycapillary half‐lens made in our laboratory was used in a series of XRF microanalysis tests using white beam. The overall efficiency of the system was studied by means of establishing detection limits for various elements in an organic sample. Copyright © 2008 John Wiley & Sons, Ltd.     

一种新型的微束X射线荧光谱仪及其在考古学中的应用

介绍了一种新型的基于X光透镜的微束X射线荧光分析系统的结构、性能和特点及其在考古学中的应用.X光透镜将旋转阳极X射线发生器产生的X射线束聚成直径为几十微米的光束，实现了对考古样品的无损、原位、微区的分析.为了检验微束分析系统的可行性，分析了一片明代青花瓷残片中青花部位的元素分布，结果表明青花中Mn和Co元素的含量与青花颜色的深浅相一致；相关性分析表明Mn和Co呈现非常好的线性相关；Mn和Co的含量或比值对青花的产地和真伪的辨别有着重要的意义. 关键词： X光透镜 微束X射线荧光 青花     

Confocal three-dimensional micro X-ray fluorescence based on synchrotron radiation for mineral analysis

The confocal three-dimensional micro X-ray fluorescence using polycapillary optics and a synchrotron radiation was applied to nondestructively analyze elemental compositions of minerals, and thereby obtain the three-dimensional distributions of elements in the minerals. Such confocal micro X-ray fluorescence had potential applications in the mineral prospecting, identification of jades, differentiation of stones.     

Application of Three Dimensional Confocal Micro X-Ray Fluorescence Technology Based on Polycapillary X-Ray Lens in Analysis of Rock and Mineral SamplesSCIEI北大核心CSCD

Confocal three dimensional (3D) micro X-ray fluorescence (XRF) spectrometer based on a polycapillary focusing X-ray lens (PFXRL) in the excitation channel and a polycapillary parallel X-ray lens (PPXRL) in the detection channel was developed. The PFXRL and PPXRL were placed in a confocal configuration. This was helpful in improving the signal-to-noise ratio of the XRF spectra, and accordingly lowered the detection limitation of the XRF technology. The confocal configuration ensured that only the XRF signal from the confocal micro-volume overlapped by the output focal spot of the PFXRL and the input focal spot of the PPXRL could be detected by the detector. Therefore, the point-to-point information of XRF for samples could be obtained non-destructively by moving the sample located at the confocal position. The magnitude of the gain in power density of the PFXRL was 10(3). This let the low power conventional X-ray source be used in this confocal XRF, and, accordingly, decreased the requirement of high power X-ray source for the confocal XRF based on polycapillary X-ray optics. In this paper, we used the confocal 3D micro X-ray fluorescence spectrometer to non-destructively analyzed mineral samples and to carry out a 3D point-to-point elemental mapping scanning, which demonstrated the capabilities of confocal 3D micro XRF technology for non-destructive analysis elements composition and distribution for mineral samples. For one mineral sample, the experimental results showed that the area with high density of element of iron had high density of copper. To some extent, this reflected the growth mechanisms of the mineral sample. The confocal 3D micro XRF technology has potential applications in such fields like the analysis identification of ore, jade, lithoid utensils, "gamble stone" and lithoid flooring.     

毛细管X光透镜三维共聚焦微束X射线荧光技术在岩矿样品分析中的应用

利用毛细管X光透镜搭建了三维共聚焦微束X射线荧光谱仪,处在激发道的多毛细管X射线会聚透镜和处在探测道的多毛细管X射线平行束透镜处于共聚焦状态,该共聚焦结构降低了X射线荧光光谱的背底,从而有利于降低的X射线荧光分析技术的探测极限。在上述共聚焦结构中,多毛细管X射线会聚透镜和多毛细管X射线平行束透镜的焦斑重合形成共聚焦微元,探测器只能探测到来自该共聚焦微元内的X射线荧光信号,当该共聚焦微元在样品移动时,就可利用该共聚焦技术原位无损得到样品内部的三维X射线荧光信息。该共聚焦技术使用的多毛细管X射线会聚透镜具有103量级的功率放大倍数,从而降低了该共聚焦技术对高功率X射线源的依赖程度,即利用低功率普通X射线源就可以设计毛细管X光透镜共聚焦X射线荧光技术。利用上述共聚焦微束X射线荧光谱仪对两种岩矿样品进行三维无损分析,在其中一种岩石中发现：Fe浓度大的区域Cu的浓度也大,这在一定程度上反映了岩矿自然生长的机理。实验结果证明：该共聚焦X射线荧光技术可以在不破坏样品情况下分析岩矿样品中元素成分组成和元素三维分布情况。该共聚焦三维微束X射线荧光技术在矿石勘察、玉器选材和鉴别、石质食用器皿、“赌石”和家用石质地板检测等领域具有潜在的应用。     

利用毛细管X光透镜共聚焦微束X射线荧光技术对单根头发中元素空间分布进行无损扫描分析

头发中的元素与人的饮食和健康状况有关,对头发中元素的分析,不仅可用于刑事物证鉴别,还可为疾病的预防和治疗提供依据,因此,如何检测头发中元素分布等信息倍受人们关注。本文利用基于毛细管X光透镜和实验室普通X射线光源的共聚焦微束X射线荧光技术对单根头进行了无损扫描分析,分析了单根头发中元素的空间分布。在该毛细管X光透镜共聚焦微束X射线荧光技术中,毛细管X光会聚透镜的出口焦斑和毛细管X光平行束透镜的入口焦斑处在共聚焦状态,从而形成共聚焦微元,探测器只能探测到来自该共聚焦微元中的X射线信号,降低了背底信号对X射线荧光谱的影响,从而有利于提高该共聚焦X射线荧光技术的分析精度。该共聚焦技术中采用了具有高功率密度增益的毛细管X光会聚透镜,降低了该共聚焦X射线荧光技术对X射线光源功率的要求,从而保证了该共聚焦技术可以采用实验室普通X射线光源,降低了实验成本。实验表明,毛细管X光透镜共聚焦微束X射线荧光技术在单根头发元素分布检测中具有应用价值。     

A new microfocus x‐ray source,iMOXS, for highly sensitive XRF analysis in scanning electron microscopes

Scanning electron microscopes are usually equipped with energy‐dispersive X‐ray detectors for electron probe microanalysis. This widespread analytical method allows investigators to determine the elemental composition of specimens with a spatial resolution of about 1 µm. However, owing to the electron–specimen interaction, the emitted spectra reveal, in addition to characteristic lines, also a high level of continuous bremsstrahlung background. As a result, elements with low concentrations cannot be identified. The minimum detection limit can be diminished by two orders of magnitude if the characteristic lines are excited as fluorescence by an additional x‐ray source. In this case, the emergence of bremsstrahlung is considerably reduced. Combining a high‐brilliance microfocus x‐ray tube with efficient polycapillary optics enables one to realize an experimental arrangement for performing local fluorescence analysis at the same point where the electron beam hits the sample. The polycapillary optics under consideration focuses the emitted x‐radiation onto focal spots between 30 and 100 µm in diameter. Count rates of several thousands cps have been achieved. Elemental maps have been obtained by means of the motorized specimen stage of the microscope. Copyright © 2005 John Wiley & Sons, Ltd.     

The energy dispersive scheme of X‐ray fluorescence analysis with a crystal polarizer and polycapillary optics

The efficiency of the polarization scheme based on polycapillary optics and a diamond crystal polarizer was demonstrated. The scheme provides suppression of the background of scattered radiation in measuring X‐ray fluorescence spectra. A quasi‐parallel X‐ray beam with an angular divergence of 4.2 mrad was formed by a microfocus source with a copper anode and polycapillary half‐lens. Simultaneous polarization and monochromatization of radiation was obtained with a crystal of natural diamond, which was set at the diffraction reflection (113). The degree of polarization of CuK_α1 spectral line and the maximum radiation flux were respectively equal to 99.86% and 5 · 10⁶ photon/s. In the direction orthogonal to the plane of diffraction, the maximum attenuation of the background was up to 19 dB.     

Detailed characterization of polycapillary focusing x-ray lenses by a charge-coupled device detector and a pinhole

A method to measure the detailed performance of polycapillary x-ray optics by a pinhole and charge coupled device (CCD) detector was proposed in this study. The pinhole was located between the x-ray source and the polycapillary x-ray optics to determine the illuminating region of the incident x-ray beam on the input side of the optics. The CCD detector placed downstream of the polycapillary x-ray optics ensured that the incident x-ray beam controlled by the pinhole irradiated a specific region of the input surface of the optics. The intensity of the output beam of the polycapillary x-ray optics was obtained from the far-field image of the output beam of the optics captured by CCD detector. As an application example, the focal spot size, gain in power density, transmission efficiency, and beam divergence of different parts of a polycapillary focusing x-ray lenses (PFXRL) were measured by a pinhole and CCD detector. Three pinholes with diameters of 500, 1000, and 2000 μm were used to adjust the diameter of the incident x-ray beam illuminating the PFXRL from 500 μm to the entire surface of the input side of the PFXRL. The focal spot size of the PFXRL, gain in power density, transmission efficiency, and beam divergence ranged from 27.1 μm to 34.6 μm, 400 to 3460, 26.70% to 5.38%, and 16.8 mrad to 84.86 mrad, respectively.     

A simple calibration procedure of polycapillary based portable micro‐XRF spectrometers for reliable quantitative analysis of cultural heritage materials

Portable micro‐X‐ray fluorescence (micro‐XRF) spectrometers mostly utilize a polycapillary X‐ray lens along the excitation channel to collect, propagate and focus down to few tens of micrometers the X‐ray tube radiation. However, the polycapillary X‐ray lens increases the complexity of the quantification of micro‐XRF data because its transmission efficiency is strongly dependent on the lens specifications and the propagated X‐ray energy. This feature results to a significant and not easily predicted modification of the energy distribution of the primary X‐ray tube spectrum. In the present work, we propose a simple calibration procedure of the X‐ray lens transmission efficiency based on the fundamental parameters approach in XRF analysis. This analytical methodology is best suited for compact commercial and portable micro‐XRF spectrometers. The developed calibration procedure is validated through the quantitative analysis of a broad range of samples with archeological relevance such as glasses, historical copper alloys, silver and gold alloys offering an overall accuracy of less than 10%–15%. Copyright © 2015 John Wiley & Sons, Ltd.     

第三代同步辐射光源X射线相干性测量研究

随着高性能第三代同步辐射光源的建成开放,基于X射线相干特性的实验方法得到了快速发展和广泛应用.作为一个典型的例子,X射线相位衬度成像已经成为常规的X射线实验方法并向用户开放.相干散射、相干衍射成像、光子关联谱等X射线实验方法正日益受到重视,在高空间分辨、时间分辨等研究领域已显示出其独特的优越性.因此,研究和测量第三代同步辐射的空间相干特性对进一步发展这些新的实验方法具有重要意义.基于Talbot自成像原理成功测量了上海光源X射线成像线站发射的X射线的空间相干长度,并进而测得了相应光源的空间尺度.光子能量为33.2 keV时,测得的X射线光束垂直方向空间相干长度为8.84μm,对应的光源尺寸为23μm,测量结果与理论分析相符.     

Analysis of extended focal area of polycapillary lenses

The X-ray passage through a polycapillary lens and the formation of X-ray energy area in the focal area of the lens (i.e., in the space behind the output cross section of the lens) are studied.     

High-resolution X-ray imaging—a powerful nondestructive technique for applications in semiconductor industry

The availability of high-brilliance X-ray sources, high-precision X-ray focusing optics and very efficient CCD area detectors has contributed essentially to the development of transmission X-ray microscopy (TXM) and X-ray computed tomography (XCT) with sub-50 nm resolution. Particularly, the fabrication of high aspect ratio Fresnel zone plates with zone widths approaching 15 nm has contributed to the enormous improvement in spatial resolution during the previous years. Currently, Fresnel zone plates give the ability to reach spatial resolutions of 15 to 20 nm in the soft and of about 30 to 50 nm in the hard X-ray energy range. X-ray microscopes with rotating anode X-ray sources that can be installed in an analytical lab next to a semiconductor fab have been developed recently. These unique TXM/XCT systems provide an important new capability of nondestructive 3D imaging of internal circuit structures without destructive sample preparation such as cross sectioning. These lab systems can be used for failure localization in micro- and nanoelectronic structures and devices, e.g., to visualize voids and residuals in on-chip metal interconnects without physical modification of the chip. Synchrotron radiation experiments have been used to study new processes and materials that have to be introduced into the semiconductor industry. The potential of TXM using synchrotron radiation in the soft X-ray energy range is shown for the nondestructive in situ imaging of void evolution in embedded on-chip copper interconnect structures during electromigration and for the imaging of different types of insulating thin films between the on-chip interconnects (spectromicroscopy).     

Parametrization of a tabletop micro-XRF system

A table-top micro X-ray fluorescence apparatus composed of a conventional X-ray tube with a polycapillary lens and a silicon drift X-ray detector was parametrized according to an independent parameter approach. The tube bremsstrahlung spectrum was calculated from the Bethe-Heitler equation, convoluted by the energy distribution of radiating electrons in the target. In this paper, we propose a simple analytical approximation for this energy distribution. An analytical approximation is also proposed for transmission of the lens composed of curved capillaries.     

Anomalous scattering,transport, and spatial distribution of X-ray fluorescence at the exit of polycapillary structures

The angular distribution of the X-ray intensity at the exit of microchannel plates at grazing incidence of monochromatic radiation on the walls of microcapillaries has been investigated. The angles and energies of the primary radiation quanta at which the synchrotron beam excites X-ray fluorescence propagating inside polycapillary structures have been determined. The angular dependences of the intensity distribution of X-rays transmitted through the microcapillaries have been studied theoretically and experimentally for energies corresponding to the region of anomalous dispersion near the L _2,3 absorption edges of silicon. The propagation of waves in hollow polycapillary waveguides, the excitation of X-ray fluorescence, and the X-ray diffraction at the exit of microchannel plates have been modeled mathematically. The mathematical model takes into account the presence of a transition layer on the microchannel surface.     

International Seminar on Advanced Accelerator and Radiation Physics

In the framework of the International Year of Light and Light-Based Technologies, a global initiative of the United Nations, the National Research Nuclear University MEPhI in Moscow dedicated one of the meetings of the series Advanced Accelerator and Radiation Physics (AARP) to “Ancient Radiations: New Physics and High-Tech Applications.” Chaired by M. N. Strikhanov and S. B. Dabagov, the AARP series of international meetings is dedicated to frontier topics in fundamental and applied research associated with new techniques of beam acceleration, novel powerful radiation sources, and applications based on radiation physics. Previous events were held at NRNU MEPhI, at the National Laboratories of Frascati (LNF-INFN), at CERN, at the Naples' Institute of Engines (IM CNR), the CEA Cadarache Research Center, and at Adyge State University in Maykop. They were dedicated to novel techniques for electron beam acceleration, to advanced methods for free electron lasing, to Compton scattering of relativistic electrons in a strong laser field, to the plasma Wakefield acceleration technique, advanced X-ray optical solutions for studying both fundamental and applied physics (e.g., incoherent and coherent X-ray imaging by tabletop facilities), novel X-ray spectroscopy instrumentation, powerful X-ray source studies by means of polycapillary optics, etc., as well as research performed in the framework of collaborations among LNF-INFN and MEPhI, the Tomsk Politechnic University, the Lebedev Physical Institute of the Russian Academy of Sciences, the CNR, and the CEA.