测量XAFS谱的全电子产额技术

在北京同步辐射实验室XAFS实验站上建立了利用全电子产额方法探测XAFS的实验方法。通过测量单色X－射线在样品表面激发出的电子产额随X－射线能量的变化，提取在吸收边附近的XAFS震荡。对不同厚度Cu薄膜的测量表明，在Cu的K吸收边附近可观察到信噪比很好的XAFS震荡。该探测器设计简单，可以直接在大气下工作。全电子产额XAFS方法的建立，有助于导电薄膜和材料的近表面结构研究。     

GMX型同轴高纯锗探测器用于X射线荧光分析之性能评述

本文以GMX型为例评述了同轴高纯锗探测器在X射线荧光分析中之应用情况,计算了锗的Kα逃逸所致之逃逸峰的强度。给出了能量分辨和逃逸峰的实验数据,并同Si(Li)探测器比较,提出了锗探测器的应用场合以及选择激发源的注意点。     

基于固体探测器SDD的XAFS数据获取系统

X射线吸收精细结构谱学(X-ray Absorption Fine Structure,XAFS)的发展,提出了对低浓度(痕量)元素研究的需求,高灵敏度的固体探测器纷纷被应用到XAFS技术中来。硅漂移探测器(Silicon Drift Detector,SDD)是一种高计数率、高能量分辨率、采用半导体制冷的小型荧光探测器,其商业产品渐趋成熟。北京同步辐射装置1W2B实验站装备了这种小型SDD,并开发了相应采谱软件供用户使用。经过对含Cu 100 mg·L~(-1)浓度的CuSO_4溶液的测试,结果证明这套新的采谱系统可以满足1W2B实验站XAFS实验荧光模式的需求。     

厚型气体电子倍增探测器(THGEM)在15～70 keV X射线测量中的应用

本文采用了自主研发的THGEM探测器,其具有双膜结构,64路直流读出电子学等特点。采用该THGEM探测器在K荧光装置上,开展了对15~70 ke V内多能量点X射线的探测实验工作;结果显示该THGEM探测器对宽能区、高注量(剂量当量)的X射线具有良好线性响应,并分析了影响探测效率的因素。     

p型超纯硅探测器

P型硅单晶通常用来制备具有几个毫米厚的Si(Li)探测器,如果象高纯锗一样,硅单晶的纯度足够高,它不需要进行锂漂移就可制成较厚的硅探测器。此种探测器在使用时需冷却,而在保存时可回暖到室温。我们应用浙江大学研制的超纯硅单晶,制成了灵敏面积为50mm~2、厚度为1.73mm的探测器Si(Hp)-82101,在77K下,测得对~(207)Bi1063.4keV跃迁的K内转换电子能量分辨率为1.72keV,这已超过目前用高阻硅和Si(Li)探测器测量所获得的最好分辨率水平1.9keV。     

金-硅面垒型探测器的制备

一、引言金-硅面垒型探测器具有下列的特点:能量分辨率高;脉冲上升时间短;耗尽层宽度可调节,因而能甄别不同的射线;脉冲高度与能量之间的线性响应好;对γ射线、中子本底不灵敏,适于在γ射线、中子本底较高的情况下测量带电粒子;工艺简单,成本较低等等。因此,自1949年麦凯(K.G.McKay)首先利用半导体探测器探测射线以来,它在核辐射探测领域中得到了很大的发展。关于金-硅面垒型探测器的制作工艺、探测原理、性能和应用已有报导。     

一种便携式能量色散X射线荧光分析仪的设计

研制了一种便携式能量色散X射线荧光分析仪(EDXRF)。激发源采用国产小口径Mo靶X线管,以变频技术设计了配套的高压电源和灯丝电源,探测器为电制冷半导体探测器。通过元素Cu、Zn、Ni、Pb的能谱测量,研究了该分析仪的检测性能和能量定标曲线,并且从理论上分析了其最佳元素分析范围。     

LaBr3（Ce）探测器在爆炸物检测中的应用

LaBr3(Ce)探测器具有高的能量分辨率和良好的能量线性响应等特点,在γ射线的测量中展示了优良的性能。本工作基于爆炸物检测的应用背景,介绍了LaBr3(Ce)探测器的特性、现状和研究进展,采用标准γ源对其性能进行了测试,并与BaF2、NaI(Tl)、LaCl3(Ce)等几种探测器进行了比较。结果表明,LaBr3(Ce)探测器在爆炸物检测方面具有良好的应用前景。     

基于EPICS的硬X微聚焦实验站数据采集系统

上海光源(SSRF)硬X射线微聚焦实验站在EPICS(Experimental Physics and Industrial Control System)软件环境下建立的控制和数据采集系统已成功用于微束X射线荧光分析、微束透射X射线吸收精细结构(XAFS)和微束荧光XAFS等实验.使用和测试结果表明:该系统用户界面简捷、控制及数据采集的功能完整、可靠性高、能极大提高实验效率.     

薄窗型多阳极气体探测器研究进展

薄窗型气体探测器是最近发展并用于低能量加速器质谱探测技术。该探测器的入射窗采用氮化硅膜,薄而均匀,分辨率高,目前已在低能量粒子探测技术中得到初步应用,显示出广泛的应用前景。本文主要从薄窗型气体探测器基本原理、薄氮化硅膜与Mylar膜的对比、不同质子数Z的低能量粒子脉冲高度对比、薄窗型气体探测器与硅探测器的对比,以及应用等方面进行阐述。     

Development of X-ray dark-field imaging towards clinical application

Review of X-ray dark-field imaging under development is presented. Its goal is its application to clini-cal diagnosis of organs that have been invisible by the ordinary techniques. In order to clinically visualize tissues in detail one needs high contrast and high spatial resolution say～50μm. This X-ray optics comprises a Bragg asymmet-ric monochro-collimator and a Bragg case or a Laue case filter with capability of analyzing angle in a parallel posi-tion. Their diffraction index is 4,4,0 and the X-ray energy 35 keV (λ=0.0354 nm). The filter has 0.6 mm thickness in the Bragg case or 1.075 mm or 2.15 mm thickness in the Laue case. Under this condition only the refracted X-rays from object can transmit through the filter while the beam that may receive absorption and/or phase change will not.Soft tissues at human joints thus taken show high contrast images so that the DFI is promising for clinical diagnosis.Preliminary X-ray absorption images of another clinical candidates of ear bones are also shown.     

Coherent X-radiation of relativistic electrons in a single crystal under asymmetric reflection conditions

Coherent X-radiation of a relativistic electron crossing a single crystal plate with constant speed is considered in the two-wave approximation of the dynamic diffraction theory [Z. Pinsker, Dynamical Scattering of X-rays in Crystals, Springer, Berlin, 1984] in a Laue geometry. Analytical expressions describing the spectral-angular distribution of parametric X-radiation (PXR) and diffracted transition radiation (DTR) formed on a system of parallel atomic planes situated at an arbitrary angle δ to the surface of the crystal plate (asymmetric reflection) are derived. The dependences of the PXR and DTR spectral-angular density and their interference with angle δ are studied.     

The Borrmann effect in parametric X-radiation under asymmetric reflection conditions

Parametric X-radiation (PXR) of a relativistic electron traversing a single crystal plate is considered in Laue geometry. The expressions describing spectral-angular distributions of PXR formed on the atomic planes situated under arbitrary angle δ to surface of the plate (asymmetric reflection) obtained on basis of two-wave approximation of dynamic diffraction theory are used for definition of the conditions of the most pronounced manifestation of the Borrmann effect (optimal value of angle δ) are clarified. This effect leads to considerable increase of the intensity of the quasi-monochromatic tuning source of coherent X-radiation built on basis of PXR.     

A thin film approach to protein crystallography

A novel approach for the investigation of proteins or macromolecules is outlined in this conceptual study. The preparation of grapho-epitaxial layers on nanotemplated substrates is proposed as an alternative to the preparation of single crystals by vapour diffusion techniques. Crystal structure investigations of such layers may then be performed via grazing-incidence diffraction (GIXRD) in the Laue mode. Quantitative expressions for the position and intensities of XRD peaks in this geometry are presented that fully consider the effects of refraction and absorption. A simulation of the Laue-GIXRD pattern of single-crystalline layers of Concanavalin A is given. The main challenges of the approach are concluded to relate to the preparation of single-crystalline protein layers. However, if those obstacles could be overcome, a 10–100-fold faster sample throughput would become possible.     

Texture, residual strain, and plastic deformation around scratches in alloy 600 using synchrotron X-ray Laue micro-diffraction

Deformation around two scratches in Alloy 600 (A600) was studied nondestructively using synchrotron Laue differential aperture X-ray microscopy. The orientation of grains and elastic strain distribution around the scratches were measured. A complex residual deviatoric elastic strain state was found to exist around the scratches. Heavy plastic deformation was observed up to a distance of 20 μm from the scratches. In the region 20-30 μm from the scratches the diffraction spots were heavily streaked and split indicating misoriented dislocation cell structures.     

层叠式Si-PIN伽玛探测器

利用Monte-Carlo方法对新研制的层叠式Si-PIN伽玛探测器的伽玛灵敏度进行了理论计算。结果表明，层叠式Si-PIN伽玛探测器相对于单个的Si-PIN探测器具有更高的灵敏度，而且伽玛灵敏度与每层间的聚四氟乙烯片的厚度有关。实验测量的层叠式探测器和普通单个探测器对1.25MeV的伽玛灵敏度与理论计算值相当。     

延迟线阳极微通道板两维成像探测器

介绍了延迟线两维位置灵敏探测器的原理、结构,制作了有效面积直径达70mm的微通道板延迟线探测器,并利用辐射源对研制的探测器位置分辨、线性响应等性能进行了测试,得到的最好位置分辨为0．1mm。讨论了进一步优化探测器性能的方法。     

CdZnTe探测器在天文物理研究中的应用综述

文章主要对CdZnTe探测器在天文物理研究中的应用进行综述.介绍了CdZnTe晶体的主要性质和CdZnTe探测器的工作原理,归纳总结了CdZnTe探测器在天文物理研究中的应用情况,从四个方面对CdZnTe探测器在天文物理研究中的应用特点和发展趋势进行了讨论.     

基于峰值保持电路的GEM探测器前端读出ASIC设计

介绍了一种用于多层GEM探测器的低噪声前端读出ASIC芯片.针对GEM探测器输出信号特点,设计了电荷灵敏放大器、整形电路和峰值保持电路,并对其噪声、成形时间等设计指标参数进行了分析.     

First results from the Lund NMP particle detector system

The design and first results from a Double Sided Silicon Strip Detector (DSSSD) recently installed at the Lund Nuclear Microprobe facility (NMP) are presented. The detector has 64 sector strips and 32 ring strips, which in combination give more than 2000 detector cells, each with characteristics comparable with a standard surface barrier detector (SBD).The detector has been tested both with radioactive sources and with different ion beams and energies. The most striking features are the high rate virtually pile-up free operation and also the possibility of detailed measurement of angular distributions.