首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 62 毫秒
1.
 介绍一种可产生超短脉冲的新型X射线光源。它由多碱光电阴极、金靶及铍输出窗组成。当该X射线管的阴极受到强光照射时,产生光电子发射,并经电场加速后轰击金靶,产生连续谱的X射线轫致辐射,经铍窗输出。用超短的可见光脉冲驱动该光源,并借助X射线扫描相机测量了该管的X射线输出,获得了5ps的X射线脉冲。这种光源可方便地用来标定X射线扫描相机的时间分辨率,此种产生超短电子脉冲的方法也可在其他方面获得应用。  相似文献   

2.
利用轫致辐射激发原子产生X射线荧光,经吸收边过滤,研制成单色低中能X射线发生器。实验给出5—25keV能区的4个单能点的强度、纯度以及相应的剂量率,可供刻度使用。  相似文献   

3.
评述了发现X射线100年来的主要发展历程、我国学者的贡献以及X射线应用于分析领域的种种特点.  相似文献   

4.
一种新型的软X射线二极管   总被引:3,自引:0,他引:3  
王红斌  孙宗慈 《物理》1994,23(9):561-565
介绍了用于激光等离子体发射的X射线量测量的一种新型的软X射线二极管(即XRD〕的结构、原理、性能、标定及其应用。该探测器具有体积小、响应快、使用方便等优点,1990年和1991年已两次成功地用于“神光”装置上激光等离子体发射X射线测量。  相似文献   

5.
单次脉冲X光摄影,已有四十多年的发展历史,较为广泛地应用于各种瞬态过程的分析。但连续脉冲X光摄影,仍是一项尚未完全成熟的技术。特别是单X光管,单发生器的连续摄影装置,更是方兴未艾。本文介绍了脉冲X光高速连续摄影的国内外研制现状,对几种摄影机结构形式作了比较。以作者几年来的科研实践为基础,重点介绍其中一种-单X光管单发生器的连续脉冲X光机,包括它的原理结构、用途和技术特点,以及存在问题和发展动向。  相似文献   

6.
X射线全息术   总被引:19,自引:1,他引:18  
本文介绍了X射线全息术的工作原理和进展状况,详细地论述了与X射线全息术有关的X射线光学、X射线光学元件和X射线源的特性,并讨论了X射线全息实验的要求和记录方式,最后着重探讨了包括记录过程和重现过程中影响X射线全息术分辨率的各种因素。  相似文献   

7.
X射线衍射进展简介   总被引:4,自引:0,他引:4  
解其云  吴小山 《物理》2012,41(11):727-735
100年前,劳厄等证明X射线对硫酸铜晶体具有衍射能力,揭开了X射线衍射分析晶体结构的序幕.100年的发展,X射线衍射已经成为自然科学乃至医学、考古、历史学等众多学科发展的必备技术.文章介绍了X射线衍射现象的发现历史,X射线运动学和动力学理论的发展概况,并举例说明了X射线衍射在粉末多晶体、单晶体和人工功能晶体以及人工薄膜材料中的具体应用情况,最后简要展望了X射线衍射技术的发展前景.  相似文献   

8.
W.H.布拉格的科学生涯与科学贡献   总被引:3,自引:1,他引:2  
厚宇德 《大学物理》2004,23(9):50-56
W.H.布拉格是20世纪伟大的英国科学家,但长期以来物理学界对他的了解不够全面.本文回顾了W.H.布拉格的人生轨迹,较系统地介绍了他的科学贡献,揭示了一些令人深思的问题,对他在科学界的深远影响也作了充分肯定  相似文献   

9.
介绍一种可产生超短脉冲的新型X射线光源。它由多碱光电阴极、金靶及铍输出窗组成,当该射线管的阴极受到强光照射时,产生光电子发射,并经电场加速后轰击金靶,产生连续谱的X射线轫致辐射,经铍窗输出。用超短的可见光脉冲驱动该光源,并借助X射线扫描相机测量了该管的X射线输出,获得了5ps的X射线脉冲,这种光源可方便地用来标定X射线扫描相机的时间分辨率,此种产生超短电子脉冲的方法可在其他方面获得应用。  相似文献   

10.
波长色散X射线荧光仪器进展   总被引:3,自引:0,他引:3  
本文叙述了自1990年以来波长色散X射线荧光光谱仪及分析技术的最新进展,介绍分为波长色散X射线荧光分析仪的整机特点,设计思想的发展,新技术应用,计算机及软件发展和定性定量分析等部分。  相似文献   

11.
An X‐ray one‐dimensionally focusing system, a refracting–diffracting lens (RDL), composed of Bragg double‐asymmetric‐reflecting two‐crystal plane parallel plates and a double‐concave cylindrical parabolic lens placed in the gap between the plates is described. It is shown that the focal length of the RDL is equal to the focal distance of the separate lens multiplied by the square of the asymmetry factor. One can obtain RDLs with different focal lengths for certain applications. Using the point‐source function of dynamic diffraction, as well as the Green function in a vacuum with parabolic approximation, an expression for the double‐diffracted beam amplitude for an arbitrary incident wave is presented. Focusing of the plane incident wave and imaging of a point source are studied. The cases of non‐absorptive and absorptive lenses are discussed. The intensity distribution in the focusing plane and on the focusing line, and its dependence on wavelength, deviation from the Bragg angle and magnification is studied. Geometrical optical considerations are also given. RDLs can be applied to focus radiation from both laboratory and synchrotron X‐ray sources, for X‐ray imaging of objects, and for obtaining high‐intensity beams. RDLs can also be applied in X‐ray astronomy.  相似文献   

12.
The possibility of splitting a thin (e.g. undulator) X‐ray beam based on diffraction–refraction effects is discussed. The beam is diffracted from a crystal whose diffracting surface has the shape of a roof with the ridge lying in the plane of diffraction. The crystal is cut asymmetrically. One half of the beam impinges on the left‐hand part of the roof and the other half impinges on the right‐hand side of the roof. Owing to refraction the left part of the beam is deviated to the left whereas the right part is deviated to the right. The device proposed consists of two channel‐cut crystals with roof‐like diffraction surfaces; the crystals are set in a dispersive position. The separation of the beams after splitting is calculated at a distance of 10 m from the crystals for various asymmetry and inclination angles. It is shown that such a splitting may be utilized for long beamlines. Advantages and disadvantages of this method are discussed.  相似文献   

13.
The ESRF synchrotron beamline ID22, dedicated to hard X‐ray microanalysis and consisting of the combination of X‐ray fluorescence, X‐ray absorption spectroscopy, diffraction and 2D/3D X‐ray imaging techniques, is one of the most versatile instruments in hard X‐ray microscopy science. This paper describes the present beamline characteristics, recent technical developments, as well as a few scientific examples from recent years of the beamline operation. The upgrade plans to adapt the beamline to the growing needs of the user community are briefly discussed.  相似文献   

14.
Here, soft X‐ray synchrotron radiation transmitted through microchannel plates is studied experimentally. Fine structures of reflection and XANES Si L‐edge spectra detected on the exit of silicon glass microcapillary structures under conditions of total X‐ray reflection are presented and analyzed. The phenomenon of the interaction of channeling radiation with unoccupied electronic states and propagation of X‐ray fluorescence excited in the microchannels is revealed. Investigations of the interaction of monochromatic radiation with the inner‐shell capillary surface and propagation of fluorescence radiation through hollow glass capillary waveguides contribute to the development of novel X‐ray focusing devices in the future.  相似文献   

15.
A microfocus X‐ray fluorescence spectroscopy beamline (BL‐16) at the Indian synchrotron radiation facility Indus‐2 has been constructed with an experimental emphasis on environmental, archaeological, biomedical and material science applications involving heavy metal speciation and their localization. The beamline offers a combination of different analytical probes, e.g. X‐ray fluorescence mapping, X‐ray microspectroscopy and total‐external‐reflection fluorescence characterization. The beamline is installed on a bending‐magnet source with a working X‐ray energy range of 4–20 keV, enabling it to excite K‐edges of all elements from S to Nb and L‐edges from Ag to U. The optics of the beamline comprises of a double‐crystal monochromator with Si(111) symmetric and asymmetric crystals and a pair of Kirkpatrick–Baez focusing mirrors. This paper describes the performance of the beamline and its capabilities with examples of measured results.  相似文献   

16.
The majority of the beamlines at the Brazilian Synchrotron Light Source Laboratory (LNLS) use radiation produced in the storage‐ring bending magnets and are therefore currently limited in the flux that can be used in the harder part of the X‐ray spectrum (above ~10 keV). A 4 T superconducting multipolar wiggler (SCW) was recently installed at LNLS in order to improve the photon flux above 10 keV and fulfill the demands set by the materials science community. A new multi‐purpose beamline was then installed at the LNLS using the SCW as a photon source. The XDS is a flexible beamline operating in the energy range between 5 and 30 keV, designed to perform experiments using absorption, diffraction and scattering techniques. Most of the work performed at the XDS beamline concentrates on X‐ray absorption spectroscopy at energies above 18 keV and high‐resolution diffraction experiments. More recently, new setups and photon‐hungry experiments such as total X‐ray scattering, X‐ray diffraction under high pressures, resonant X‐ray emission spectroscopy, among others, have started to become routine at XDS. Here, the XDS beamline characteristics, performance and a few new experimental possibilities are described.  相似文献   

17.
The coupling and propagation of electromagnetic waves through planar X‐ray waveguides (WG) with vacuum gap and Si claddings are analyzed in detail, starting from the source and ending at the detector. The general case of linearly tapered WGs (i.e. with the entrance aperture different from the exit one) is considered. Different kinds of sources, i.e. synchrotron radiation and laboratory desk‐top sources, have been considered, with the former providing a fully coherent incoming beam and the latter partially coherent beams. It is demonstrated that useful information about the parameters of the WG can be derived, comparing experimental results with computer simulation based on analytical solutions of the Helmholtz equation which take into account the amplitude and phase matching between the standing waves created in front of the WG, and the resonance modes propagating into the WG.  相似文献   

18.
Inelastic X‐ray scattering instruments in operation at third‐generation synchrotron radiation facilities are based on backreflections from perfect silicon crystals. This concept reaches back to the very beginnings of high‐energy‐resolution X‐ray spectroscopy and has several advantages but also some inherent drawbacks. In this paper an alternate path is investigated using a different concept, the `M4 instrument'. It consists of a combination of two in‐line high‐resolution monochromators, focusing mirrors and collimating mirrors. Design choices and performance estimates in comparison with existing conventional inelastic X‐ray scattering instruments are presented.  相似文献   

19.
Third‐generation synchrotron radiation sources pose difficult challenges for energy‐dispersive detectors for XAFS because of their count rate limitations. One solution to this problem is the bent crystal Laue analyzer (BCLA), which removes most of the undesired scatter and fluorescence before it reaches the detector, effectively eliminating detector saturation due to background. In this paper experimental measurements of BCLA performance in conjunction with a 13‐element germanium detector, and a quantitative analysis of the signal‐to‐noise improvement of BCLAs are presented. The performance of BCLAs are compared with filters and slits.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号