Study of a bulk-Micromegas with a resistive anode

The design and performance of a Micromegas with a resistive anode are presented in this paper. A thin resistive sheet with volume resistivity of 10¹² Ω·m cm is glued onto the readout electrode surface and its performance is investigated by using a ⁵⁵Fe X-ray radioactive source in the operation gas of argon and isobutene mixtures (Ar/Iso=95/5). The gas gain at different mesh high voltage, counting rate and working time are given. Energy spectra at different working voltages are measured and the results are discussed. We have oberved that a Micromegas with a resistive anode can be operated at higer gain than a standard Micromegas without sparks.     

Study of measuring methods on spatial resolution of a GEM imaging detector

In this paper, the limitations of the common method measuring intrinsic spatial resolution of the GEM imaging detector are presented. Through theoretical analysis and experimental verification, we have improved the common method to avoid these limitations. Using these improved methods, a more precise measurement of intrinsic spatial resolutions are obtained.     

RIBLL终端LASCAR闪烁体阵列探测器研制进展

介绍了RIBLL终端LASCAR闪烁体阵列探测器的工作原理和结构特点. 描述了为满足放射性核束实验的要求而对阵列所作的重要改进. 给出了LASCAR构型优化改造的工作设想和实施步骤. The principles and structure characteristics of LASCAR scintillator array detector at RIBLL terminal are described. Special emphases are laid upon the latest progress for the development of LASCAR array detector to meet the requirements of the RIB experiments. The working plan and steps for optimizing configuration of the LASCAR multi unit neutron scintillator array detector are also presented.     

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.     

基于一代像增强器的高分辨率X射线相机

为了实现在较低剂量下获得较高的分辨率,研制了一款价格低廉的X射线CCD相机。该相机使用硫氧化钆作为转换屏、经一代像增强器增强后的图像通过光锥耦合到CCD相机上;为了提高系统的光传输效率,提出了将像增强器输出直面板或倒像器直接更换成光锥,其小端直接同CCD相机耦合的方案;通过灰度分析计算对比度曲线,拟合得出系统的本征空间分辨率为13 Lp/mm;通过拍摄实际景物,可以清晰地看到其内部的细节,显示出比较好的图像质量。     

HIRFL-CSRm内靶实验终端CsI(Tl)电磁量能器性能模拟

基于GEANT4模拟了HIRFL CSRm内靶实验终端的CsI(Tl)电磁量能器系统,给出了CsI电磁量能器的最佳设计参数及可能达到的性能.结果表明,设计的CsI(Tl)电磁量能器系统能够满足所研究的物理要求. Based on the GEANT4, the performance of the electromagnetic calorimeter (EMC) of the internal-target detector at HIRFL-CSRm is simulated. The simulation results show that 1.5%—3% of the energy resolution σ_E/E and 2° of the polar angular resolution σ_θ can be obtained. The invariant mass of the π~0 decay can be reconstructed well. The performance can meet the requirement of studying the proposed physics at HIRFL-CSRm.     

一维丝室气体探测器衍射像差的修正方法研究

一维位置灵敏单丝气体探测器采用单根镀金钨丝和200根阴极感应条的探测结构, X射线在阳极丝上产生的信号被多个阴极条感应, 利用重心法得到X射线的原初电离点的位置信息, 位置分辨率达到160 μm(半高全宽). 在同步辐射衍射实验中, X射线通过样品后会形成不同大小的衍射环, 本实验中测量得到11.148°和14.201°的两组衍射角位置信息; 通过平行移动一维探测器在衍射环范围内多次扫描, 可以重建得到二维衍射环. 由于一维探测器的气体厚度和入射窗宽度会给测量结果带来像差, 分析发现像差的影响大于一维探测器的位置分辨. 基于相应的物理分析对测量到的衍射位置进行修正, 修正后的衍射位置相比修正前的衍射位置的相对像差最大改善达到7%, 该方法实现了无像差二维衍射环的重建.     

Beam test of a one-dimensional position sensitive chamber on synchrotron radiation

A one-dimensional single-wire chamber was developed to provide high position resolution for powder diffraction experiments with synchrotron radiation. A diffraction test using the sample of SiO₂ has been accomplished at 1W2B laboratory of Beijing Synchrotron Radiation Source. The data of the beam test were analyzed and some diffraction angles were obtained. The experimental results were in good agreement with standard data from ICDD powder diffraction file. The precision of diffraction angles was 1% to 4.7%. Most of the relative errors between measured values of diffraction angles and existing data were less than 1%. As for the detector, the best position resolution in the test was 138 μm (σ value) with an X-ray tube. Finally, discussions of the results were given. The major factor that affected the precision of measurement was deviation from the flat structure of the detector. The effect was analyzed and the conclusion was reached that it would be the optimal measurement scheme when the distance between the powder sample and detector was from 400 mm to 600 mm.     

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.     

散裂中子源高气压二维位置灵敏3He探测器的实验研究

为满足中国散裂中子源多功能反射谱仪中子探测器的基本物理要求:有效面积达到200 mm×200 mm、探测效率大于50%（2Å）、位置分辨好于2 mm等,中国科学院高能物理研究所研制了3He高气压二维多丝正比室位置灵敏中子探测器。该探测器采用二维多丝室结构,腔体内充3He/C₃H₈（6 atm/2.5 atm）的组合气体。本文首先利用Am/Be中子源完成对探测器全面积均匀性测试,均匀性指标达到了95.1%;探测器在中国散裂中子源的20号束流线站安装后,对其进行了在束测量,通过飞行时间选取波长2.8Å的慢中子,测量了探测器二维位置分辨和二维成像性能。在X方向（垂直于阳极丝的方向）的位置分辨为0.99 mm,Y方向（平行于阳极丝的方向）的位置分辨为1.36 mm,探测器具有很好的二维位置分辨和二维成像能力。测量结果表明探测器满足反射谱仪的研制要求。