A simulation study of the e~+/e~- sensitivity of a low resistive phosphate glass electrode in a RPC using GEANT MC

The resistivity of conventional glass is quite high and is unacceptable in a high rate environment. Low resistive glass-electrodes could be a solution for this problem. The present study reports the e+/e-simulation results of an RPC detector made from low resistive phosphate glass electrodes. The detailed geometrical configuration of the content materials which are the essential components of the glass of the RPC detector have been created with the GEANT4 simulation code. Two different types of particle sources, i.e. for e+/e-, have been located on the detectors surface to evaluate the performance of the phosphate glass RPC. Both of the particles have been simulated as a function of their respective energies in the range of 0.1 MeV – 1.0 GeV. The present simulation work has shown that the resistive electrode plays an important role for the particle production in the RPC configuration.     

大面积玻璃RPC模型与性能测试

介绍了可用于粒子探测的大面积玻璃高阻板探测器RPC(Resistive Plate Chamber).使用两块间隔2mm的普通浮法玻璃作为电极,其中充入流动的混合气体(氩气+异丁烷+F134A),工作高压约9600V;性能测试结果,其单室效率可达97%,时间分辨可达到1.8ns.     

Simulation study using GEANT4 Monte Carlo code for a Gd-coated resistive plate chamber as a thermal neutron detector

The Resistive Plate Chamber (RPC) has been developed in many application areas ever since its introduction, from high energy physics experiments to positron emission tomography. Such detectors can be coated with a Gd layer that enables them to detect thermal neutrons. Consequently these RPCs can be utilized for industrial and medical purposes. Here, we present the configuration of a resistive plate chamber which is utilized to detect thermal neutrons by employing GEANT4 Monte Carlo code. The response of the RPC was evaluated as a function of neutron energy in the GEANT4 Monte Carlo code. The simulation results are taken for incident neutron energy in the energy range from 25 meV to 100 meV. The detection efficiency was found to be between 10% and 20%, depending on the detector configuration, for incident thermal neutrons of 25 meV energy.     

GEANT4 simulation of gamma ray in a double-gap resistive plate chamber

For more than 20 years nuclear physicists have used the GEANT code to simulate particle-matter interaction. In most recent version, GEANT4 is a toolkit for simulating the passage of particles though matter, which contains a complete range of functionality including tracking, geometry, physics models, and hits. In this article, an attempt to use GEANT4 to model a double-gap resistive plate chamber （RPC） with its improved efficiency is presented. The efficiencies of the double-gap RPC have been evaluated as a function of gamma energy range 0.005-1000MeV. A comparison to available previous simulation package GEANT3 data is also performed.     

Measurement of avalanche size and position resolution of RPCs with different surface resistivities of the high voltage provider

The effects of surface resistivity of the high voltage provider on the space dispersion of the induced charge of a prototype Resistive Plate Chamber (RPC) have been studied experimentally and theoretically. The results of both experiment and theory agree and confirm that a two-Gaussian function can be used to fit the dispersion of the induced charge of the RPC. It is shown that the Gaussian function with the narrower width is mainly due to the expansion of the avalanche charge in the gas gap of the RPC, and the Gaussian function with the larger width is due to the charge dispersion when it passes through the resistive carbon film. This will be useful in the RPC design when one wants to make an RPC with high position resolution.     

大面积阻性板探测器的研制

介绍了使用自制的材料制作的大面积阻性板探测器模型的结构和利用宇宙射线测量的效率曲线、单计数率曲线、暗电流曲线、多重计数和信号幅度随高压的变化曲线.结果表明,该RPC效率接近98%,单计数率和暗电流都好于国外的同类探测器,完全可以满足通常实验的要求.     

Angular distribution of cosmic muons using INO–ICAL prototype detector at TIFR

The India-based Neutrino Observatory Collaboration is planning to set up a magnetized 50 kt iron calorimeter (ICAL) with resistive plate chambers (RPC) as active detectors to study neutrino oscillations and precisely measure its parameters.?A prototype detector stack is set up at TIFR (18°54??N, 72°48??E) to track cosmic ray muons.?Using the muon data, angular distribution of cosmic ray muons at the sea level is studied here.     

Study of neutron response for two hybrid RPC setups using the GEANT4 MC simulation approach

The present article describes a detailed neutron simulation study in the energy range 10~(-10) MeV to 1.0 GeV for two different RPC configurations.The simulation studies were taken by using the GEANT4 MC code.Aluminum was utilized on the GND and readout strips for the (a) Bakelite-based and (b) glass-based RPCs.For the former type of RPC setup the neutron sensitivity for the isotropic source was S_n=2.702×10~(-2) at E_n=1.0 GeV, while for the latter type of RPC, the neutron sensitivity for the same source was evaluated as S_n=4.049×10~(-2) at E_n=1.0 geV.These results were further compared with the previous RPC configuration in which copper was used for ground and pickup pads.Additionally A1 was employed at (GND+strips) of the phosphate glass RPC setup and compared with the copper-based phosphate glass RPC.Good agreement with sensitivity values was obtained with the current and previous simulation results.     

基于阻性阳极读出方法的气体电子倍增器二维成像性能

新型微结构气体探测器,如气体电子倍增器(gas electron multiplier,GEM)等,具有非常好的位置分辨率潜力(σ100μm),但是需要匹配大规模高密度的读出电子学,给探测器的建设、造价、功耗、空间利用等带来极大压力.阻性阳极读出方法可以在保持较高位置分辨率的前提下,大幅节省电子学.基于厚膜电阻工艺,一种新的阻性单元阵列结构被成功开发和应用于三级级联GEM探测器的读出阳极.该阻性阳极包括6×6个6 mm×6 mm的基本阻性单元,仅需匹配49路读出电子学.~(55)Fe放射源(5.9 keV)和X光机(8 keV)实验的结果显示探测器的位置分辨率(σ)可好于80μm,位置非线性好于1.5%.同时,探测器还获得了很好的实物成像效果.探测器的优良性能表明这种阻性阳极读出方法适用于大面积二维成像气体探测器的读出,并可用于其他探测器的读出.     

Preliminary results from India-based Neutrino Observatory detector R&;D programme

We are currently developing and studying the performance of glass RPC prototypes, under the INO detector R&D programme. While we were successful in building and characterising a large number of chambers using local glass, these have met with severe aging problems after a few months of continuous operation. We have then built a couple of RPCs using a Japanese glass. We report in this paper on our long term stability tests of these RPCs. We also present some of our recent results on tracking of cosmic ray muons in a stack of glass RPCs. India-based Neutrino Observatory Collaboration     

Cosmic ray test for a T0 detector

The endcap of time-of-flight (ETOF) detector in BES (Beijing Spectrometer) III is planned to be upgraded by using multi-gap resistive plate chambers (MRPCs) and the designed time resolution of the MRPCs is around 50 ps. Thus a time-zero (T0) detector needs to be built to offer a high quality reference time for the MRPCs beam test. So a T0 detector is built using plastic scintillator tiles (BC420) to couple with four fast phototubes (PMTs, Hamamatsu H6533). The timing properties of the detector is studied by using a cosmic ray test and factors related to the time resolution, such as plastic scintillator size, readout mode and angle effects, are discussed. T0 detector timing resolutions of ～41-62 ps are achieved, which means that the T0 detector can be used in the MRPC beam test.     

Background neutron in the endcap and barrel regions of resistive plate chamber for compact muon solenoid/large hadron collider using GEANT4

In this study the performance of double gap RPC has been tested by GEANT4 Monte Carlo simulation code. The detector response calculations taken as a function of the neutron energy in the range of 0.01 eV-1 GeV have been simulated through RPC set-up. In order to evaluate the response of detector in the LHC background environment, the neutron spectrum expected in the CMS muon endcap and barrel region were taken into account. A hit rate of about 165.5 Hz cm⁻², 34 Hz cm⁻², 33.6 Hz cm⁻², and 27.0 Hz cm⁻² due to an isotropic neutron source is calculated using GEANT4 standard electromagnetic package for a 20 × 20 cm² RPC in the ME1, ME2, ME3 and ME4, respectively. While for the same neutron source and using GEANT4 package a hit rate of about 0.42 Hz cm⁻², 0.7182 Hz cm⁻² was measured for the MB1 and MB4 stations respectively. Similar characteristics of hit rates have been observed for GEANT4 low electromagnetic package.      

Effect of the integrated time of the induced current signal on the position resolution of the RPC detector

A prototype RPC with position resolution less than 1 mm has been produced and studied. Based on this RPC detector, the effect of the width of the integrated FADC time window on the position resolution of a RPC has been studied experimentally and theoretically. The results of theoretical calculation and experimental measurement have shown good agreement.     

Effect of the integrated time of the induced current signal on the position resolution of the RPC detector

A prototype RPC with position resolution less than 1 mm has been produced and studied. Based on this RPC detector, the effect of the width of the integrated FADC time window on the position resolution of a RPC has been studied experimentally and theoretically. The results of theoretical calculation and experimental measurement have shown good agreement.     

Investigation of high resolution compact gamma camera module based on a continuous scintillation crystal using a novel charge division readout method

The objective of this study is to investigate a high performance and lower cost compact gammacamera module for a multi-head small animal SPECT system.A compact camera module was developed usinga thin Lutetium Oxyorthosilicate(LSO)scintillation crystal slice coupled to a Hamamatsu H8500 positionsensitive photomultiplier tube(PSPMT).A two-stage charge division readout board based on a novel subtractive resistive readout with a truncated center-of-gravity(TCOG)positioning method was developed for the camera.The performance of the camera was evaluated using a flood 99mTc source with a four-quadrant bar-mask phantom.The preliminary experimental results show that the image shrinkage problem associated with the conventional resistive readout can be effectively overcome by the novel subtractive resistive readout with an appropriate fraction subtraction factor.The response output area(ROA)of the camera shown in the flood image was improved up to 34%,and an intrinsic spatial resolution better than 2 mm of detector was achieved.In conclusion,the utilization of a continuous scintillation crystal and a flat-panel PSPMT equipped with a novel subtractive resistive readout is a feasible approach for developing a high performance and lower cost compact gamma camera.     

Design,development and performance study of six-gap glass MRPC detectors

The multigap resistive plate chambers (MRPCs) are gas ionization detectors with multiple gas sub-gaps made of resistive electrodes. The high voltage (HV) is applied on the outer surfaces of outermost resistive plates only, while the interior plates are left electrically floating. The presence of multiple narrow sub-gaps with high electric field results in faster signals on the outer electrodes, thus improving the detector’s time resolution. Due to their excellent performance and relatively low cost, the MRPC detector has found potential application in time-of-flight (TOF) systems. Here we present the design, fabrication, optimization of the operating parameters such as the HV, the gas mixture composition, and, performance of six-gap glass MRPC detectors of area 27 cm \(\times \) 27 cm, which are developed in order to find application as trigger detectors, in TOF measurement etc. The design has been optimized with unique spacers and blockers to ensure a proper gas flow through the narrow sub-gaps, which are 250 \(\upmu \)m wide. The gas mixture consisting of R134A, Isobutane and SF\(_{6}\), and the fraction of each constituting gases has been optimized after studying the MRPC performance for a set of different concentrations. The counting efficiency of the MRPC is about 95% at 17.9 kV. At the same operating voltage, the time resolution, after correcting for the walk effect, is found to be about 219 ps.     

高通量下GEM探测器高压供电模式研究

GEM探测器的供电一般采用电阻链分压供电模式和多路分立供电模式,在低通量X射线下测量时区别不大,但是在高通量X射线时,电阻链分压供电模式会带来饱和效应引起工作电压的变化,造成探测器工作不稳定。本研究在高通量X 射线照射下,研究了有效面积为100 mm100 mm三层级联GEM探测器的有效增益(稳定性) 与不同高压供电模式的关系。通过测量不同分压电阻值(1, 2, 5 到30 MΩ)的实验研究,发现随着X 射线通量的增加,在电阻链分压供电模式下,出现了GEM探测器感应电极的读出电流饱和趋势,分析了可能导致饱和效应出现的原因。结果表明,当入射X射线在探测器上的有效吸收剂量不断增加时,电阻链供电模式需要调整分压单元电阻值,或者采用多路分立供电模式,从而避免因饱和效应引起的GEM探测器有效增益的变化,实现探测器稳定的工作状态。There are two methods of the HV power supply for the GEM detector. One is a HV channel divided by the resistive chain and the other is the several separate HV channels. In the smaller dose rate of X-ray, all of the methods are similar. When the dose rate increases, the resistive chain-dividing mode has more obvious saturation effect and the working voltage of the GEM detector is unstable. In the paper, a GEM detector with an effective area of 100 mm100 mm has been studied in the high dose rate using X-tube. The unit values in the divider resistance chain are set to 1, 2, 5 and 30 MΩ respectively in the test. With the resistive chain-dividing mode, the readout current of the GEM detector’s anode tends to saturate when the dose rate of X-ray increases,and the reasons of the saturation effect are analyzed. The results indicate that the effective absorbed dose of X-ray by the triple GEMs detector reaches to the pecific value and the divider resistance needs to re-select, even the several separate HV channels mode should be considered. It will keep the constant of the working voltage of the GEM detector without the saturation effect and gain variation and the performance of GEM detector is stable.     

Thick GEM with a resistive coating

The results of testing a detector based on a thick gas electron multiplier (GEM) are presented. Impact of the TGEM dielectric charging on detector physical parameters is assessed based on simulation and experimental results. The further development of the detector—TGEM with resistive coating was constructed and tested. The test results are presented and compared to a standard thick GEM.