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.     

束流实验中不同尺寸塑料闪烁体的时间特性

北京谱仪(BESⅢ)中的飞行时间探测器将采用长2.3m宽6cm的长条形塑料闪烁体. 利用北京高能物理研究所的实验束流对铝膜包装的不同厚度闪烁体的本征时间分辨进行了研究,给出了4cm, 5cm和6cm闪烁体的时间分辨, 而且用蒙特卡罗模拟做了比较, 结果表明5cm厚的闪烁体具有最佳性能.     

Equivalent detector models for the simulation of efficiency response of an HPGe detector with PENELOPE code

ABSTRACT

In this work, some ‘equivalent’ models for the simulation of efficiency response of a High-Purity Germanium (HPGe) detector, installed inside a ‘low background’ bunker in the Engineering Department of the University of Palermo, were developed. The main feature was to attribute the uncertainties of the model to only one of the parameters, the dead layer of the detector, keeping unchanged the other data provided by the manufacturer. With this technique, using the Monte Carlo PENELOPE code in the 2011 version, the efficiency response was evaluated and compared with the previous one performed with MCNP5 code.

The validation of equivalent models is performed by comparing the simulation results with that of experimental spectrometric measurements of calibrated point sources and characterized volumetric sources such as a Marinelli beaker and an air filter reduced to a ‘packet-sample’.

The use of equivalent models makes the evaluation of efficiency curves with a Monte Carlo code easier and faster, and requires only a few experimental values for validation.     

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.     

用于中国散裂中子源多功能反射谱仪的高气压多丝正比室探测器的研制

中国散裂中子源需要建设一台多功能反射谱仪中子探测器,满足在10年运行期间内,50%(@2A)以上的探测效率、好于2 mm的二维位置分辨、200 mm×200 mm的灵敏面积、3倍的n/γ分辨能力及良好的二维成像性能.基于此要求,探测器因此采用基于高气压~3He气体的多丝正比室,并以满足反射谱仪的探测效率、位置分辨、长期稳定工作和n/y分辨能力为目标进行探测器的设计.本文经过模拟和实验计算得出:以9 mm厚的铝合金入射窗、铝丝密封的高气压腔体和6 bar~3He+2.5 bar C_3H_8的工作气体的设计,可满足探测器对2 A中子10年运行期间内54%以上的探测效率要求;探测器对中子的位置分辨可达到1.4 mm左右;设计的气体净化系统,拥有2 L/min的气流速度可有效去除探测器内的负电性杂质气体,气体循环净化后可提高探测器约27%的气体增益,保证探测器长期稳定的运行;通过对~(252)Cf中子源的能谱测量和成像测量,得出探测器的n/γ分辨能力在5倍以上和均匀的成像结果.研制的探测器满足反射谱仪需求,并已在中国散裂中子源反射谱仪靶站就位联调.     

γ射线和PET用晶体单元相互作用特性的研究

γ射线与晶体单元的相互作用特性对于PET探测器的研制有着重要的参考意义. 通过实验测得了不同能量的γ射线在BGO, CsI, NaI 3种闪烁晶体中的探测效率、 能量分辨率等相互作用特性参数, 并与蒙特卡洛模拟结果进行了比较. 结果给出了最适合PET探测器的晶体单元. It’s important for development of PET detector that the interaction effect of γ rays and scintillator units are studied. The detection efficiencies and energy resolutions of γ rays for BGO, CsI and NaI crystal detector units are measured. Geant4 Monte Carlo simulations are compared with the experimental results. The results of the best detection units for PET detector are presented.     

高能伽玛相机探测量子效率的蒙特卡罗模拟

探测量子效率（DQE）可被用来精确描述图像噪声通过成像系统的传播特性。根据级联理论,简洁得出了零频噪声传播情况下成像系统的DQE 表达式。采用蒙特卡罗程序MCNP 计算了高能X射线的硬化能谱在六种常用闪烁晶体中的能量沉积分布以及高能伽玛相机的DQE,分析了闪烁晶体的材料和厚度对DQE的影响。模拟结果表明,高密度、高原子序数是影响DQE的主要因素,在同样厚度下,LuAP和LSO转换屏的探测量子效率最高。     

BESⅡ上光子探测效率的研究

利用J/ψ→ρπ衰变道,对BESⅡ上BSC对于光子的探测效率做了细致的研究.结果表明在从探测器光子能量阈值直到BES上可产生的最大光子能量范围内,用目前的Monte Carlo可以在1%—3%的精度下模拟光子的探测效率.并且对Monte Carlo在探测效率上与数据的差别进行了详细研究.同时用质心系能量s=3.770GeV处的e+e–→γe+e–数据检验了高能区MonteCarlo和数据的探测效率都达到100%,并且在1%精度下是一致的     

Method for developing HPGe detector model in Monte Carlo simulation codes

This paper describes a simulation model for a high-purity germanium (HPGe) detector by scanning the detector with a low-energy collimated source and calibrating the efficiency of the detector. The parameters of the initial simulation model, particularly the dead-layer thickness, were modified step by step according to the experimental results. The validity of codes, models, and methods was shown by implementing the model into the FLUKA and MCNPX codes and cross-checking against the experimental data.     

Monte Carlo simulation of GM probe and NaI detector efficiency for surface activity measurements

This paper deals with the direct measurement of total (fixed plus removable) surface activity in the presence of interfering radiation fields. Two methods based on Monte Carlo simulations are used: one for a Geiger–Muller (GM) ionisation probe and the other for sodium iodide (NaI) detector with lead collimators; equations for the most general case and the geometry models for Monte Carlo simulation of both (GM and NaI) detectors are employed. Finally, an example of application is discussed.     

基于Monte Carlo模拟的三种不同结构单电子动态存储器特性比较

关键词：     

利用MC模拟研究MRPC性能

利用Monte Carlo方法模拟了多气隙电阻板室(MRPC)的气体雪崩和信号收集过程,通过模拟与实验数据的比较分析,研究了MRPC粒子探测效率和信号幅度等性能,并讨论了一些外部条件的影响.     

井型高纯锗探测器体源样品无源效率刻度

采用蒙特卡罗程序MCNP建立物理模型,对井型高纯锗探测器的效率进行虚拟刻度。模拟计算在密度为0.4,1.2 gcm-3的6种不同成分环境样品中,探测器对射线的探测效率,当能量高于0.10 MeV时,体源样品的探测效率主要与样品密度、射线能量相关。以土壤、水和植物油样品为代表,结合所选取的函数模型,确定了密度范围0.1~1.6 gcm-3的固体源、密度1.0 gcm-3的水溶液和密度0.92 gcm-3的油溶液体源的效率函数及参数。实验采用标准源,对探测效率模拟结果进行了验证,探测效率的模拟值与实验值符合较好,二者误差均在3%以内。说明MCNP程序可以较为准确地模拟计算井型高纯锗探测器对射线的探测效率,验证了该无源效率刻度方法的准确性和可行性。     

血液中Na活化放射性测量的蒙特卡罗模拟

针对超临界事故中人体受到中子辐照后感生的24Na活度测量,采用MCNP软件建立蒙特卡罗模拟模型,分别模拟不同类型NaI探测器对24Na衰变的两条射线全能峰的探测效率和塑料闪烁体探测器对24Na衰变的射线总计数的探测器效率。模拟结果表明:井型NaI探测器与圆柱型相比,24Na衰变的1.38 MeV和2.76 MeV 射线全能峰探测效率分别提高了4.30倍和4.11倍;塑料闪烁体探测器对24Na衰变的射线的探测效率是NaI探测器对24Na 射线的探测效率的1.72倍;同时粗略计算了探测器计数与人体所受中子辐照剂量之间的关系。     

血液中Na活化放射性测量的蒙特卡罗模拟

针对超临界事故中人体受到中子辐照后感生的24Na活度测量,采用MCNP软件建立蒙特卡罗模拟模型,分别模拟不同类型NaI探测器对24Na衰变的两条射线全能峰的探测效率和塑料闪烁体探测器对24Na衰变的射线总计数的探测器效率。模拟结果表明：井型NaI探测器与圆柱型相比,24Na衰变的1.38 MeV和2.76 MeV 射线全能峰探测效率分别提高了4.30倍和4.11倍;塑料闪烁体探测器对24Na衰变的射线的探测效率是NaI探测器对24Na 射线的探测效率的1.72倍;同时粗略计算了探测器计数与人体所受中子辐照剂量之间的关系。     

14 MeV neutron detection characteristics using Intercast detector

Neutron detection with a stack of two detector foils of CR-39 (intercast) was studied. A comparison between the experimental results (exposure to 14.8 MeV neutrons) and the results of a computer simulation was performed. Emphasis was given to the detection of particles—products of the break-up reaction of the ¹²C nucleus—and to heavier recoil nuclei. The detectors were chemically etched and analysed with an automatic counting system. All detector surfaces were analysed, and the coincidence tracks produced by the same particles on detector surfaces in contact were determined. These tracks facilitate characterization of the type and energy of the recoil nuclei. Further separation was made on the basis of the distribution of size and darkness of the tracks.     

闪烁光纤时间特性的蒙特卡罗模拟

用蒙特卡罗模拟的方法，研究了影响闪烁光纤时间分辨的物理因素，包括光子在光纤中的发射，传输，吸收和最后在光电倍增管输出端形成电泳冲等过程，并和实验结果进行了比较。     

Design and simulations for the detector based on DSSSD

The present paper describes the design and simulation results of a position-sensitive charged particle detector based on the Double Sided Silicon Strip Detector （DSSSD）. Also, the characteristics of the DSSSD and its testing result were are discussed. With the application of the DSSSD, the position-sensitive charged particle detector can not only give particle flux and energy spectra information and identify different types of charged particles, but also measure the location and angle of incident particles. As the detector can make multi-parameter measurements of charged particles, it is widely used in space detection and exploration missions, such as charged particle detection related to earthquakes, space environment monitoring and solar activity inspection.     

Design and simulations for the detector based on DSSSD

The present paper describes the design and simulation results of a position-sensitive charged particle detector based on the Double Sided Silicon Strip Detector (DSSSD). Also, the characteristics of the DSSSD and its testing result were are discussed. With the application of the DSSSD, the position-sensitive charged particle detector can not only give particle flux and energy spectra information and identify different types of charged particles, but also measure the location and angle of incident particles. As the detector can make multi-parameter measurements of charged particles, it is widely used in space detection and exploration missions, such as charged particle detection related to earthquakes, space environment monitoring and solar activity inspection.     

Development of a sub-millimeter position-sensitive gas detector

Position-sensitive thin-gap gas detectors have been developed in the laboratory, based on the ATLAS Thin Gap Chamber. The signal collection structure has been redesigned while retaining other configurations to keep the good time performance of the detector. The position resolution was measured using cosmic muons for two versions of the detector and found to be 409 μm and 233 μm respectively. This paper presents the structure of these two detector prototypes, with the position resolution measurement method and results.