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.     

BFEL自发辐射和受激辐射的光学诊断

实验给出北京自由电子激光自发辐射与受激辐射实验的光学诊断结果，并简要介绍了ＢＦＥＬ红外谱仪系统的数据处理方式。利用光学诊断结果对电子束时间谱分析的新方法也进行了讨论，并对其可行性做了分析。     

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.     

Bulk工艺气体微网探测器的研究

In this paper, we present a study of a micromegas detector prototype built with bulk technology. Following a short discussion of the micromegas detector＇s structure and working mechanism, the bulk fabrication process is described, and some testing results of the prototype 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。     

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.     

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.     

TGA和Py-GC/MS研究不同氛围下烟草的热失重和热裂解行为

应用热重红外联用技术(TG-FTIR)和热裂解气相色谱-质谱联用技术(Py-GC/MS)对卷烟烟丝的热失重和热裂解行为及其裂解产物进行研究.采用热重分析法测定不同气氛下卷烟样品的热失重(TG)、微商热重(DTG)曲线,以及热裂解过程中H2O、CO2、CO、NH3和CH4等气体物质的释放量.结果表明,裂解气氛不同可以显著...     

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.