Investigation of the energy resolution with a RETGEM detector

A novel Micro-pattern gaseous detector （MPGD）, thick GEM with electrodes made of a resistive material （RETGEM） is presented. In this paper we mainly investigate the energy resolution of a RETGEM in Ar＋CO2 with different gas mixtures. The results indicate that an energy resolution 30% in single and double mode can be obtained. The existence of an optimum energy resolution is discussed.     

用于快中子探测的裂变电离室实验及模拟结果比较(英文)

本文报道了一种用于快中子测量的裂变电离室的实验及模拟结果对比,该电离室的裂变材料为238U,分别电镀在电离室的阳极和阴极。裂变电离室通常有三种工作模式:脉冲模式、均方电压模式和电流模式,从而在大动态范围内实现中子注量测量。我们利用252Cf中子源对工作在脉冲模式的裂变电离室效率进行了测量,同时为了评估均方电压模式和电流模式,测量了裂变电离室在不同气压下的脉冲幅度,并通过Geant4蒙特卡罗软件对裂变电离室的脉冲幅度进行了模拟。模拟可以解释实验结果,当工作气压是2.64×105 Pa时探测效率最高[（4.30±0.7）×10-7],且裂变碎片能谱清晰,表明裂变电离室可以工作在不同模式下。     

MICROMEGAS一维位置编码读出初步测试

介绍了微型网状结构的气体探测器一维位置编码读出的基本原理和实现方法。设计了一块灵敏面积为10 cm×10 cm的一维位置编码PCB读出电极。测试表明: 感应读出是可行的, 电荷按1∶2分配最为理想; 利用55Fe放射源X射线通过200 μm狭缝对准读出电极PCB板的正面中任意一条, 位置编码读出能很好地再现源所在狭缝的位置。针对其局限性, 提出了一维位置分组编码读出技术, 以解决相邻多条同时点火的情况。使用该读出技术, 使一维读出电子学路数节省量达到75%以上。The basic principles and implementation of one dimensional position encoding read out for MICROMEGAS have been introduced in this paper. A 10 cm×10 cm prototype of one dimensional position encoding read out electrode based on printed circuit board was designed. Preliminary test indicates that the induction read out is feasible and the ideal charge distribution is 1∶2. X rays emitted from 55Fe source were collimated to one of strips on the read out electrode through a slit of 200 μm, position decoding well reproduced the position of the 55Fe source. For its limitations, we have proposed a one dimensional grouped position encoding read out technique to address a neighboring strips simultaneously fired situation. The amount of read out electronics is very easy to approach a obduction of 75% with position encoding read out technology.     

Prototype studies on the forward MWDC tracking array of the external target experiment at HIRFL-CSR

A prototype of the forward tracking array consisting of three multiwire drift chambers (MWDC) for the external target experiment (CEE) at the Heavy Ion Research Facility at the Lanzhou -Cooling Storage Ring (HIRFL-CSR) has been assembled and tested using cosmic rays. The signals from the anode wires are amplified and fed to a Flash-ADC to deliver the drift time and charge integration. The performances of the array prototype are investigated under various high voltages. For the tracking performances, after the space-time relation (STR) calibration and the detector displacement correction, the standard deviation of 223 μm of the residue is obtained. The performances of the forward MWDCs tracking array meets the requirements of CEE in design.     

CEE-TPC中GEM读出探测器传输性能实验研究

气体电子倍增器(GEM)因其具有较好的位置分辨以及各项同性的二维结构等优点,近年来受到了广泛的关注,在HIRFL-CSR上正在建设的低温高密核物质测量谱仪(CEE)也计划使用GEM作为TPC的读出探测器。不同电场条件下GEM探测器的传输特性对探测器的有效增益及能量分辨有较大影响。文中研究了单层GEM探测器中漂移区电场及感应区电场对探测器传输特性的影响;随后研究了双层GEM探测器的电压分配及传输区电场对探测器电荷传输性能的影响。结果表明,在单层及多层GEM探测器中,漂移区电场、传输区电场及感应区电场主要通过改变电子透过率和GEM雪崩电场强度及分布影响探测器的电荷传输性能,进而影响探测器的有效增益及能量分辨。以上实验结果表明GEM探测器是CEE-TPC读出探测器的理想选择,同时测试结果也为TPC中多层级联GEM工作点的选择提供了参考依据。     

RETGEM探测器的初步测试

研制了一种新型的带有阻抗性电极的TGEM——RETGEM(Thick GEM with Resistive Electrodes)探测器, 阻抗性电极可以有效地保护探测器和前端电子学免于偶尔放电的损伤。 对RETGEM探测器进行了初步测试, 其中包括计数率、能量分辨、增益以及打火率。 结果表明, 探测器达到了设计的基本要求。 In this study we present preliminary results from a new detector: a thick gaseous electron multiplier(GEM) with resistive electrodes. The resistive electrodes protect the detector and the front end electronics from damage by occasional discharges. In different gas mixtures, we test Thick GEM with Resistive Electrodes(RETGEM) detector for the first time, including counting rate, energy resolution, effective gain, and discharge probability. The results can satisfy the basic demand of RETGEM detector design.     

Performance test of the low-pressure thin window multi-wire chamber

A flow gas low-pressure multi-wire proportional chamber(LPMWPC)with an active area of 180 mm×80 mm has been developed for the flying time test of the recoil nuclei on super heavy nuclear experiments.The LPMWPC detector can be operated in single as well as double step operational modes.In the case of double step operational mode with a high gas amplification factor,signals fromα-particles reside well above the electronic noise.The gas leakage rate and time resolution obtained from theα239Pu source are shown and discussed at the condition of 3 mbar Isobutane gas.It was shown that the time resolution was better than 2.9 ns at the best work condition,and the detecting efciency was larger than 98%at the low energyαparticles.So the LPMWPC is fit to measure the flying time in the super heavy nuclear fragments experiment.     

Test and simulation of a MICROMEGAS detector

We report on the recent test results of a MICROMEGAS detector in terms of position resolution, time resolution and efficiency. With a Ar + CO₂ (10%) gas mixture and a strip pitch of 200 μm an accuracy of 80 μm in sigma on the position has been measured. The time resolution is better than 20 ns and a cosmic ray detection efficiency of 94% was obtained. A Monte Carlo simulation indicates that transverse diffusion, gain fluctuation and electronic noise limit the position resolution.     

利用MICROMEGAS探测器测量第一汤逊系数

利用新型的MICROMEGAS探测器测量了6种不同比例的Ar+CO2 混合气体中第一汤逊系数α的两个实验参数A和B。实验结果分析表明, 电子在栅极的透过率在75%时, α的测量误差小于13%, 而探测器增益的涨落造成的α的测量误差小于8%。In this paper, the MICROMEGAS detector was employed to measure the experimental parameters A and B of the first Townsend coefficient α in 6 different ratio of Ar+CO2 gas mixtures. The results indicate that the error of α is less than 13% in the condition of electron transmission rate of the mesh up to 75% and is less than 8% due to gain fluctuation of the detector.     

Micromegas探测器计数曲线、增益以及能量分辨特性的研究

介绍了自行研制的Micromegas探测器的基本结构和工作原理. 在不同工作气体(Ar和CO₂)配比条件下,利用⁵⁵Fe放射源对该探测器的能量分辨、计数曲线和气体增益等特性进行了较为详尽的测试. 对相关结果进行了讨论. 关键词： Micromegas探测器 计数曲线 能量分辨率 增益