Study of 2D interpolating readout for a micro-pattern gaseous detector

The two-dimensional interpolating readout, a new readout concept based on resistive anode structure, was studied for the micro-pattern gaseous detector. Within its high spatial resolution, the interpolating resistive readout structure leads to an enormous reduction of electronic channels compared with pure pixel devices, and also makes the detector more reliable and robust, which is attributed to its resistive anode relieving discharge. A GEM （gaseous electron multiplier） detector with 2D interpolating resistive readout structure was set up and the performance of the detector was studied with ^55Fe 5.9 keV X-ray. The detector worked stably at the gain up to 3.5 × 104 without any discharge. An energy resolution of about 19%, and a spatial resolution of about 219 μm （FWHM） were reached, and good imaging performance was also obtained.

Application of a wedge strip anode in micro-pattern gaseous detectors

The wedge strip anode （WSA） has been widely used in 2-D positiomsensitive detectors. A circular WSA with an effective diameter of 52 mm is successfully coupled to a tripe gas electron multiplier （GEM） detector through a simple resistive layer. A spatial resolution of 440 μm （FWHM） is achieved for a 10 kVp X-ray using 1 atm Ar：CO2=70：30 gas. The simple electronics of only three channels makes it very useful in applications strongly requiring simple interface design, e.g. sealed tubes and high pressure detectors.

A Portable Wireless DAQ System for Gaseous Detectors

A real-time wireless analog/digital electronic system for the data acquisition of a proportional counter detector is presented. Gaseous detectors working principle is based on the ionization of a gas due to a particle. The ions are then accelerated towards two electrodes and the read out signal is amplified, shaped and discriminated. It is then sent to the DAQ （data acquisition） electronics. The power supply system can be either the common 220 V source or a battery, whose autonomy is about 72 h during data acquisition. The analog electronics are made up of a high voltage generator for the detector＇s electrodes, an amplifier system, a shaper and a discriminator. The digital environment is based on an Arduino Mega-2560 board. A wireless modular shield is plugged on the board, in order to access the Arduino board via the 802.11b/g wireless protocol. Four temperature sensors and two pressure sensors are placed in the surroundings of the detector and they are connected to the system in order to read out environmental conditions. The software application, if required by the user, periodically acquires the data produced by the detector, formats them together with the sensor readings into a frame and sends the frame via UDP to an external server. The server plots the data on a webpage. During the data acquisition, the microcontroller continuously monitors the battery status, in order to safely stop the system in case of low battery. The DAQ system is controlled via a web page hosted inside Arduino, which acts like a server. Such page allows to set the detector working parameters （high voltage, discriminator threshold）, to start the data acquisition, to test the system via a debug panel and to read temperature and pressure sensors. Experimental results are presented.

A large area ^(3)He tube array detector with vacuum operation capacity for the SANS instrument at the CSNS

The small-angle neutron scattering(SANS)instrument,one of the first three instruments of the China Spallation Neutron Source(CSNS),is designed to probe the microscopic and mesoscopic structures of materials in the scale range 1–100 nm.A large-area ^(3)He tube array detector has been constructed and operates at the CSNS SANS instrument since August 2018.It consists of 120 linear position-sensitive detector tubes,each 1 m in length and 8 mm in diameter,and filled with ^(3)He gas at 20 bar to obtain a high detection efficiency.The ^(3)He tubes were divided into ten modules,providing an overall area of 1000 mm×1020 mm with a high count rate capability.Because each tube is installed independently,the detector can be quickly repaired in situ by replacing damaged tubes.To reduce air scattering,the SANS detector must operate in a vacuum environment(0.1 mbar).An all-metal sealing technique was adopted to avoid high-voltage breakdown by ensuring a high-voltage connection and an electronic system working in an atmospheric environment.A position resolution of 7.8±0.1 mm(full width at maximum)is measured along the length of the tubes,with a high detection efficiency of 81±2% at 2A.Operating over the past four years,the detector appears to perform well and with a high stability,which supports the SANS instrument to finish approximately 200 user scientific programs.

Simulation and optimization of a double THGEM detector

A double thick GEM (THGEM) detector with thin THGEM foils and small holes was constructed. In order to optimize the operation parameters of the detector, a simulation study of the detector was carried out using ANSYS and Garfield program. Some important characteristics, including primary electron transparency, avalanche development and the secondary electron loss were calculated. Parameters, such as electric field and gas choice were optimized.

Status of the Streamer Mode in Gas Detectors

This work shows the results of a streamer discharge mode studies in various gas detectors developed up-to-date. The results are based on a new experimental data from high-speed thin-gap gas detector application developments as well as on basic knowledge of multi-wire devices operations.

OML:an online multi-particle locating method for high-resolution single-event effects studies

Identifying sensitive areas in integrated circuits susceptible to single-event effects(SEE)is crucial for improving radiation hardness.This study presents an online multi-track location(OML)framework to enhance the high-resolution online trajectory detection for the Hi’Beam-SEE system,which aims to localize SEE-sensitive positions on the IC at the micrometer scale and in real time.We employed a reparameterization method to accelerate the inference speed,merging the branches of the backbone of the location in the deployment scenario.Additionally,we designed an irregular convolution kernel,an attention mechanism,and a fused loss function to improve the positioning accuracy.OML demonstrates exceptional realtime processing capabilities,achieving a positioning accuracy of 1.83μm in processing data generated by the Hi’Beam-SEE system at 163 frames per second per GPU.

Simulation study of the parallax ef f ect of gaseous detectors

A simulation study of the parallax effect of gaseous detectors using the Garfield program is reported. A method that mainly uses non-uniform cathode potentials to reduce the parallax error of planar type gas detectors is described. By applying it to MWPC and Micro-pattern gas detectors, the method reduces the parallax broadening with very good results. For a 13° incidence track, the width （FWHM） of the parallax broadening is reduced to less than 20% of the normal one after using the special cathode potentials.

Simulation study of the performance of new micropattern gaseous detectors

Background The micropattern gaseous detectors(MPGDs)are widely used in high-energy physics experiment,such as detector upgrade projects in LHC,due to its excellent performance on rate capability,spatial and time resolutions.Method In this paper,we studied the performances of GEM,FTM andμ-RWELL detectors on time and spatial resolutions using Monte Carlo simulation methods and compared their performances and characteristics at various working conditions.Result Result shows that time resolution of MPGDs improves with the increase of electric field intensity in drift region,while spatial resolution shows the reverse tendency.In addition,detectors operating with an electronegative gas mixture show better performances on both time and spatial resolution.Conclusion We studied the performance of triple-GEM,FTM andμ-RWELL detectors with Monte Carlo simulation.In this paper,ANSYS and GARFIELD are used to build full electric field model of the detector.The time resolution and spatial resolution are derived,which are very important for triggering performance and track reconstruction ability.These results will provide references on detector design and the technology chosen in LHC detector upgrade projects.

气相色谱技术在聚合级气态烯烃原料分析中的应用进展

介绍了聚合级气态烯烃原料中杂质的形成原因及其对聚烯烃催化剂活性的影响。根据气态烯烃原料中不同杂质的类型,阐述了气相色谱技术在烃类化合物分析、硫化物分析、氧化物分析、氯化物分析、氮化物分析、砷化氢和磷化氢分析、CO和CO2分析、水含量分析、进样系统及定量分析中的应用现状与可能的发展趋势。

环境扫描电子显微镜工作原理及实现

系统介绍了环境扫描电子显微镜(ESEM)的研制历程和采用的关键技术。从常规扫描电子显微镜(SEM)的基本工作原理出发,列出了SEM成像信号产生的方式及特点。针对SEM在实际应用中暴露出的缺陷,ESEM提出了解决问题的措施。多重狭缝的采用,使样品室内压强可以大幅提高;而气体二次电子探头(GSED)的发明,使作为成像信号的二次电子信号得到加强。

高温环境扫描电镜(KYKY1500)Ⅰ.成像原理及仪器特点

本文简要地叙述了ＫＹＫＹ１５００高温环境扫描电镜的一些基本概念：气体的电离效应，背底噪音，偏电压对信号电流的影响及图像形成的原理：并简单地介绍了本电镜的三个主要特殊系统（三级真空系统，环境信号探测系统及高温样品台）的结构与特点，此外，又给出了高温样品台中加热炉丝磁场对电子轨迹影响的计算结果。

环境扫描电子显微镜的成像特点

环境扫描电子显微镜(ESEM)中所指的环境并非真正意义上的大气环境(760 Torr),与传统扫描电子显微镜(SEM)样品室高真空度相比,ESEM样品室的真空度可以很低(约达20 Torr)。ESEM是在传统的SEM样品室中多一个GSED探头,因此,它在传统的SEM基础上增添了新的功能。其主要的特点是,可以观察含适量水分的样品和非导体材料样品,比如植物的叶片、动物中的昆虫、作物的籽粒、含结晶水的固体材料等。

甲醛快速测定仪测试性能研究

通过考察甲醛快速测定仪分析方法的线性范围、灵敏度、准确度、精密度及方法扩展不确定度等技术指标,研究环境因素如空气中干扰物、温度、湿度、风速等的影响,比较甲醛快速测定仪与国家标准方法在测试甲醛标准气体或室内空气测试结果的差异。结果证实甲醛快速测定仪分析方法的特性优异、测试结果受环境因素影响小与国家标准方法测试结果相关性好,适合测试室内空气中的甲醛气体。

微结构气体探测器中紫外激光束的信号和指向精度实验研究

在气体探测器研究中,利用266 nm紫外激光的双光子电离物理机制使气体电离产生可测量的信号,是一种重要的标定方法.随着微结构气体探测器(MPGD)的不断发展,用紫外激光标定来实现较高精度位置分辨率成为了一种研究需求,对此有两个关键技术问题需要解决:实验研究激光可测信号大小以及激光指向精度.分析和模拟计算了紫外光电离信号大小和激光调光误差,基于微结构气体电子倍增器探测器与266 nm波长激光束,在工作气体Ar/CO_2(70/30)中,测量了不同光斑面积与输出信号的关系;设计和研制了紫外激光调光系统,实验测量了紫外光调光偏差.模拟结果与实验结果对比分析表明:紫外激光束作用于气体探测器,探测器增益在5000,前放增益为10 mV/fC时, 6 mm读出条宽输出信号幅度约400 mV;在探测器内传播距离为400 mm时,较短时间内(10—20 min)实验调光指向精度可以保证小于5′,引入z向偏差最大可以达到0.33 mm,对应z向漂移速度的测量相对误差为6.4×10-4.该研究为MPGD与紫外激光标定实验设计提供主要的设计参考.

光催化涂层净化气态有机物能力评价系统

目的验证设计改进的光催化涂层净化气态有机物能力评价系统,使所设计的光催化评价系统可以准确地表征光催化涂层对如文章中所述0.25μL/L体积浓度级别的微量苯气体的降解情况。方法首次采用PID光离子化检测器在线监测污染物降解效率,并进行了适当的材料及工艺上的改进。实验以两种TiO_2光触媒涂层样品为对象,以苯作为污染物,进行了一系列性能表征实验。结果评价系统性能良好,可以准确地反应出在5~20 W/m^2可见光辐照下,两种不同光触媒涂层样品的光催化效率分别为11.7%~57.3%以及13.4%~67.4%。在实验考察的体积浓度范围0.05~0.4μL/L内,污染物浓度的变化对降解效率影响不大,而随着污染气体流速从30 m L/min增加至90 m L/min,两种涂层对污染物的降解效率变差,分别从43.6%降低到25.9%以及从52.9%降低到29.9%。结论研究设计的光催化涂层评价系统精密准确稳定,其较高的检出限能够很好地满足光催化材料对痕量气态有机污染物降解情况表征的需要,可广泛用于光催化领域气-固两相反应的科学研究及产品评价。

A novel method of encoded multiplexing readout for micro-pattern gas detectors

The requirement of a large number of electronic channels poses a big challenge to the further applications of Micro-pattern Gas Detectors （MPGDs）. By using the redundancy that at least two neighboring strips record the signal of a particle, a novel method of encoded multiplexing readout for MPGDs is presented in this paper. The method offers a feasible and easily-extensible way of encoding and decoding, and can significantly reduce the number of readout channels. A verification test was carried out on a 5 cm×5 cm Thick Gas Electron Multiplier （THGEM） detector using a 8 keV Cu X-ray source with 100um slit, where 166 strips were read out by 21 encoded readout channels. The test results show good linearity in its position response, and the spatial resolution root-mean-square （RMS） of the test system is about 260um. This method has potential to build large area detectors and can be easily adapted to other detectors similar to MPGDs.

高计数率多气隙阻性板室温度效应测试

为了提高多气隙阻性板室(MRPC)探测器的定时精度,CBM实验采用了前放电子学直接插接在探测器上的设计方案.但是电子学在高计数率的实验条件下,自身发热会带来探测器工作气体环境温度的上升.针对低电阻玻璃的自身特性,本文对应用于CBM实验的高计数率MRPC2型探测器进行了温度实验,其结果可对未来CBM-TOF的运行提供参考.

环境扫描电镜工作原理及应用

介绍了环境扫描电镜(ESEM)的工作原理及其在各类材料中的应用。ESEM继承了扫描电镜(SEM)的全部优点,在聚合物材料、非导电晶体材料、压电晶体材料、含水生物样品等的研究中得到广泛应用,并显示出其具有制样简单、样品室环境可变、有独特的像衬度原理、可观察动态过程等独特优点;ESEM尤其可以消除普通SEM无法观察含水样品以及镀导电层会掩盖样品表面精细结构的缺点。但ESEM依然还存在气体环境会对电镜造成污染、无法避免电子束轰击对样品表面造成损伤等缺点。

栅型气体电子倍增器的研制

实践中发现,微结构气体探测器(MPGD)遇到三方面挑战:打火时放电电流的抑制与稳定运行、单元面积增大后的生产工艺以及孔型结构带来的探测位置重建偏差.为解决以上问题,本文提出了一种新型结构的MPGD——栅型气体电子倍增器(Groove).使用3种不同几何尺寸的栅型电极,在不同气体中对8.04 keV铜靶X射线的能谱进行测量,以检验探测器性能.与蒙特卡罗模拟计算结果对比表明,探测器信号主要来自雪崩产生的离子.能谱测量结果显示:栅极狭缝宽度0.2 mm、厚度0.8 mm的探测器增益和能量分辨率好于其他尺寸的探测器;在93%Ar+7%CO2中运行时,探测器增益与分辨率两项指标稍好于在95%Ar+5%CH4中.测量得到的探测器增益最高可达3×10^4左右,能量分辨率最高可达15.6%.