The capabilities of multielectrode heterogeneous ionization chambers for X-ray thickness measurements

An X-ray setup featuring automatic correction of the radiation spectrum and flux is developed for measuring the thickness of articles.     

用Si光电二极管标定软X射线探测器

为了实现软X射线波段光源相对光谱分布的测量,引进了一种利用新型软X射线波段传递标准探测器—Si光电二极管对软X射线探测器进行标定.标定了软X射线波段光谱测量实验中常用的探测器—通道电子倍增器在放大电压为1.3kV时的量子效率,并对实验结果进行了分析,得出在8～30nm波段内探测器标定误差为5.7%～8.9%.     

A geophysical device for automation of multielectrode electrical prospecting

A self-contained unit used in the resistance method of the geophysical electrical prospecting in order to switch two supply and two receiving lines with 24 electrodes installed on the Earth’s surface is described. The possibility of connecting in series several devices and their soft-and hardware interfacing to the control personal computer allows the number of electrodes to be increased to several hundred. As a result, the performance and flexibility of the data acquisition system as a whole increase, allowing one to conduct investigations at a higher methodological level. The unit is a portable device with a built-in storage battery and a control panel. There are connectors for ensuring control from the computer and connecting other devices.     

X线阵探测器实时成像系统的设计

为了解决工业无损检测x线的数字化成像问题。本文介绍了一种基于TCP／IP通信协议的X射线无损检测扫描成像系统,阐述了探测器数据接收与成像的基本原理及技术实现,进行了系统硬件和软件的设计。试验结果表明,X-SCANX射线线阵列探测器可以实现16bit高速图像数据获取。空间分辨率可达0．4mm。并取得了比较满意的x射线图像效果。     

X射线脉冲星导航探测器的微通道板甄选

根据应用于X射线脉冲星导航系统的大面阵X射线探测器对微通道板(MCP)性能的要求,研究了甄选微通道板的方法。确定了甄选微通道板的4个关键参量,分别是增益的均匀性、阻抗匹配、暗计数率、增益系数。针对这4个参量设计了相应的测试实验,制定了甄选MCP的流程,并对采用该流程甄选出的MCP进行了幅值和计数率的测试。测试结果显示:采用单通道阳极接收信号时,每一个探测单元的幅值存在的相对误差各不相同,第i个探测单元输出的信号幅值的最大相对误差Δ1i和最小相对误差Δ2i的波动分别为7%~13.5%,3%~6.7%;而采用四通道共享阳极时输出信号的Δ1i为7.8%、Δ2i为3.1%;单通道阳极计数率之和(n=n1+n2+n3+n4)与四通道共享阳极计数率N的相对误差为4.38%,小于预估值10%。上述实验结果表明该甄选方法能够甄选出满足探测器要求的MCP。     

X射线掠入射聚焦型脉冲星探测器热控设计

为了保证X射线掠入射聚焦型脉冲星探测器在复杂的空间热环境中正常运行,对该探测器进行了热控设计。分析了仪器对热设计的特殊影响及相应热控措施,总结分析了仪器的在轨温度情况,并结合热设计模型获得非测温点的温度结果。在轨温度数据分析表明,除低温工况下的光学系统温度超出指标要求外,仪器关键部位的温度均在热控指标范围内,验证了仪器热控设计的正确性。低温工况下光学镜头热变形对探测器性能影响的分析表明,预测的结果与观测数据一致。     

Scanning transmission X-ray microscopy with a fast framing pixel detector

Scanning transmission X-ray microscopy (STXM) is a powerful imaging technique, in which a small X-ray probe is raster scanned across a specimen. Complete knowledge of the complex-valued transmission function of the specimen can be gained using detection schemes whose every-day use, however, is often hindered by the need of specialized configured detectors or by slow or noisy readout of area detectors. We report on sub-50 nm-resolution STXM studies in the hard X-ray regime using the PILATUS, a fully pixelated fast framing detector operated in single-photon counting mode. We demonstrate a range of imaging modes, including phase contrast and dark-field imaging.     

ARL9900X射线荧光光谱仪SC探测器故障处理

赛默飞世尔ARL9900X射线荧光光谱仪日常分析时,会出现TFe元素无成分,其它元素成分正常的现象.本文解析了X射线荧光光谱仪的工作原理,运用角度扫描和能量描迹的方法进行故障分析,确定SC探测器故障,并进行更换处理,再结合SC探测器工作原理及结构,对故障产生原因进行了探讨,总结使用维护经验.     

Mythen detector for X-ray diffraction at the Beijing synchrotron radiation facility

Time-resolved X-ray powder diffraction may be used to elucidate the structure of polycrystalline matter, but a fast-response full-profile detector is often necessary. This article describes a Mythen detector incorporated in beamline 4B9A of the Beijing Synchrotron Radiation Facility. Basic parameters of this detector are reported, and flat-field correction, angular calibration, eccentric error, and other data treatment for this detector are discussed. X-ray diffraction measurement of lanthanum boride demonstrates that this detector provides high-quality, time-resolved X-ray powder diffraction measurements.     

Dark field X-ray microscopy: the effects of condenser/detector aperture

In order to visualize the functionality of a biological cell, it is often desirable to label specific proteins. In this work we concentrate on the optical theory of visualizing colloidal gold labels with soft X-ray microscopes, where scattering from small gold spheres used as labels dominates the image. Using numerical simulations of bright and dark field imaging, we compare different configurations of condenser and objective lenses in transmission X-ray microscopes, and configurations of detector and objective lens in scanning transmission X-ray microscopes. It is verified that the contrast of small, closely spaced features is strongly affected by changes in these configurations; the optimum situation is to have the condenser aperture (in TXM) or detector aperture (in STXM) equal to 3/2 that of the objective numerical aperture.     

X-ray microscopy of plant cells by using LiF crystal as a detector

A lithium fluoride (LiF) crystal has been utilized as a new soft X-ray detector to image different biological samples at a high spatial resolution. This new type of image detector for X-ray microscopy has many interesting properties: high resolution (nanometer scale), permanent storage of images, the ability to clear the image and reuse the LiF crystal, and high contrast with greater dynamic range. Cells of the unicellular green algae Chlamydomonas dysosmos and Chlorella sorokiniana, and pollen grains of Olea europea have been used as biological materials for imaging. The biological samples were imaged on LiF crystals by using the soft X-ray contact microscopy and contact micro-radiography techniques. The laser plasma soft X-ray source was generated using a Nd:YAG/Glass laser focused on a solid target. The X-ray energy range for image acquisition was in the water-window spectral range for single shot contact microscopy of very thin biological samples (single cells) and around 1 keV for multishots microradiography. The main aim of this article is to highlight the possibility of using a LiF crystal as a detector for the biological imaging using soft X-ray radiation and to demonstrate its ability to visualize the microstructure within living cells.     

A microcantilever-based pathogen detector

The ability to detect small amounts of materials, especially bacterial organisms, is important for medical diagnostics and national security issues. Engineered micromechanical systems provide one approach for constructing multifunctional, highly sensitive, real-time, immunospecific biological detectors. We present qualitative detection of specific Salmonella enterica strains using a functionalized silicon nitride microcantilever. Detection is achieved due to a change in the surface stress on the cantilever surface in situ upon binding of a small number of bacteria. Scanning electron micrographs indicate that less than 25 adsorbed bacteria are required for detection.     

A Dual-energy X-ray detector on the basis of ZnSe(Al) and LGSO(Ce) composite scintillators

The results of tests of an experimental prototype of a two-energy scintillation detector, which is based on a two-layer composite system of fine-crystalline ZnSe(Al) and LGSO(Ce) scintillators, are presented and its properties are determined. The X-rays spectra for each element of the detector were obtained. The analysis of these spectra allowed determination of the energy efficiency of the X-ray absorption for each element of the detector in an energy range of 30–70 keV. The dependences of proper signals from photodetectors under the action of X rays (the tube voltage varied from 40 to 90 kV) were restored. The corresponding X-ray spectra are presented as well. The dependences of scintillation signals from disperse ZnSe(Al) and LGSO(Ce) scintillators on the X-ray tube voltage are presented (the voltage varied from 40 to 70 keV). Due to the high registration efficiency of relatively low-energy X rays (up to 70 keV), this detector can be used not only in engineering introscopy (customs baggage control, mail, cargo-container, and vehicle checks, etc.), but also in various fields of medical radiology.     

便携式逆反射系数测试仪

根据相关国标设计了一种便携式逆反射系数测试仪,用于测量交通标志、机动车车身标识和高能见度警示服等材料的逆反射系数。分析、比较了逆反射系数测量原理,基于相对测量法研制了逆反射系数测试仪。该逆反射系数测试仪以白色发散光作为光源,可以在近距离下模拟逆反射标识的实际工作状况,完成逆反射系数的测量。介绍了逆反射系数测试仪中光学系统、光电转换电路和STM32F103C8T6单片机控制系统的设计方法,建立了基于最小行车安全距离的逆反射系数测试角度的选择模型,完成了逆反射系数测试仪不确定度的评估。最后,利用研制的便携式逆反射系数测试仪进行了实验测试。结果显示:在测试条件为(0.1~199.9)cd·lx-1·m-2时,其示值误差的最大值为4.40%;当测试条件大于199.9cd·lx-1·m-2时,示值误差的最大值为1.31%,符合GB 26377-2010对示值误差的要求。设计的逆反射系数测试仪具有小型化和智能化的优点,对现场检测交通安全标识、机动车车身标识等具有实际意义。     

A measuring square-law diode detector

A general approach, circuit diagrams, and test results of a square-law detector with improved metrological characteristics are presented. The detector is based on a “diode + current-to-voltage converter” scheme. The measured characteristics are as follows: the dynamic range is 40 dB, and quadraticity factor is 2.00 ± 0.05. The working frequency band of a particular detector is from 0.001 to 2 GHz. The proposed approach is suitable for detectors of most kinds (series, parallel, single- and two-cycle, etc.), operating in the radio frequency band.     

A silicon strip vertex detector for LEP

The Design of a silicon strip diode detector for use at LEP is described. It will use a custom-designed NMOS read-out chip, to reduce the size and cost of the associated electronics.     

A fast-neutron detector based on single-crystalline silicon

It is shown that the change of the specific electrical conductivity (SEC) of silicon single crystals in the process of their irradiation is directly proportional to the fast-neutron fluence. This is used as the basis of the principle of the neutron-flux detection. The coefficient of proportionality depends on the neutron spectrum, but does not depend on the initial SEC, which significantly simplifies detector calibration. A set of wafers with different SEC values has been manufactured using the technology silicon neutron-transmutation doping. The SEC has been measured by the four-probe method. A simple method for measuring the SEC without recourse to any special setup is proposed. The random measurement error of the fast-neutron fluence was ～10%, and the absolute one was ～37%.     

A phoswich detector for β-ray spectrometry

The spectrometric characteristics of a scintillation phoswich detector for β-ray spectrometry are described. The phoswich detector is composed of two detectors, one of which is an inorganic scintillator (calcium chlorborate) and the other is a scintillating plastic. The background of this phoswich detector is a factor of 9.3 lower than that of a single detector based on a plastic scintillator. At the same time, the dependence of its pulse heights on the β-particle energy is shown to be linear.     

基于LabVIEW的零件尺寸公差检测仪

本文设计了一种基于LabVIEW和单片机数据采集系统的机械零件尺寸公差检测仪。单片机系统采集到的传感器数据通过串口发送至PC机,LabVIEW程序接收数据并分析,将检测结果通过人机界面显示。从下位机和上位机两个部分阐述设计。测试证明,系统能实时精确地完成测量功能。     

A vertex detector to search for beauty

This paper describes a high resolution vertex detector designed to study heavy quarks and other rare phenomena at the FNAL Tevatron machine. Its performance is examined and discussed. This vertex detector will be used in the frame of experiment E-687, being set up at Fermilab.