Improved design and construction of an ionization chamber for the CSNS beam loss monitor (BLM)

Based on the first ionization chamber (IC) prototype, the structure, working gas component and electrode material of the IC are improved. The test of the improved IC shows that the plateau length is about 2000 V, the plateau slope is less than 0.2%/100 V, the sensitivity is 19.6 pA/rad·h^-1, the up-limitation of the linearity can be up to 3.6×10⁵ rad/h, and the applied voltage can be operated to 3500 V. The test results show that the performance of the improved IC meets the requirements of the beam loss monitor.     

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.     

Experimental studies of THGEM in different Ar/CO_2 mixtures

In this paper, the performance of a type of domestic THGEM (THick Gaseous Electron Multiplier) working in Ar/CO₂ mixtures is reported in detail. This kind of single THGEM can provide a gain range from 100 to 1000, which is very suitable for application in neutron detection. In order to study its basic characteristics as a reference for the development of a THGEM based neutron detector, the counting rate plateau, the energy resolution and the gain of the THGEM have been measured in different Ar/CO₂ mixtures with a variety of electrical fields. For the Ar/CO₂(90%/10%) gas mixture, a wide counting rate plateau is achieved from 720 V to 770 V, with a plateau slope of 2.4%/100 V, and an excellent energy resolution of about 22% is obtained at the 5.9 keV full energy peak of the ⁵⁵Fe X-ray source.     

海平面宇宙射线重粒子的质量谱及通量的测量

本文介绍了一个由飞行时间测量系统构成的实验装置,描述了这个实验装置的各个组成部分和它的性能,并给出了海平面宇宙射线重粒子的质量谱及通量的测量结果。     

闪烁计数器阵列定位系统

该闪烁计数器阵列定位系统,即闪烁计数器描迹仪,不但可以确定带电粒子通过的位置,还可以用做触发计数器。在用做触发计数器时,它还具有选择落入该阵列的带电粒子数目的能力。该描迹仪为8×8闪烁计数器阵列,每条闪烁体（ST401型）为40×5×0.6cm³。配用GDB50光电倍增管。阵列面积为40×40cm²。我们自制了快电子学系统和数据读取系统,在与微处理机联试过程中,工作稳定可靠。造价低廉。     

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.     

用于GPPD谱仪的大面积闪烁体中子探测器性能测试

中国散裂中子源（Chinese Spallation Neutron Source,CSNS）的建成为中子散射技术的发展和应用奠定了基础。通用粉末衍射谱仪（general purpose powder diffractometer,GPPD）是CSNS一期建设的三条谱仪之一。研制了用于GPPD的大面积闪烁体探测器阵列,在CSNS的BL20中子束线上开展了探测器关键性能参数的实验测试。测试结果显示,对波长为1.4 Å和2.8 Å的中子,其探测效率分别为（38.5±1.7）%和（56.1±1.1）%,模拟与实验相结合,给出对2 Å的中子,其探测效率约为（46.1±2.0）%,有效面积内的探测效率不均匀度约为19.6%,经优化后可以降低到14.9%;探测器位置分辨可以达到4.0 mm×4.0 mm,最高计数率约79 kHz。探测器单元的整体性能指标能满足GPPD的物理需求。     

Installation and cosmic ray test of the high voltage system of the BESⅢ drift chamber

After examination of the designed high voltage power supply system of the BESⅢ drift chamber in the beam test of the full length prototype of drift chamber, a full system covering all the channels of high voltage was installed. The system's training and the high voltage value adjustment were carried out in the cosmic ray test of the BESⅢ drift chamber. The cosmic ray test for the full system and its final installation on the BESⅢ drift chamber were reported. The full system of high voltage power supply works stably and reliably.     

THGEM探测器X光斑寻迹和位置分辨实验研究

介绍了一种基于THGEM的X射线光斑寻迹探测器,用于X射线单光子计量技术研究和测量,探测器有效面积200 mm×200 mm,采用128路基于ASIC和FPGA的高速读出电子学,探测器分为中间高分辨区和外围低分辨区两部分,两部分共用一套读出电子学。实验在中国计量科学研究院利用X光机产生的束线,测试光斑位置、光斑精细分布以及探测器的位置分辨。实验结果表明,探测器实现了同时对光斑寻迹和光斑的精细测量,探测器中间高分辨区x方向的位置分辨率为0.63 mm（FWHM）,y方向位置分辨率为0.62mm（FWHM）,探测器各项性能指标均达到了预期目标。This paper introduces the detector of X-ray spot tracing based on the THGEM. It is used for X ray single photon measurement technology research and measurement with an effective area of 200 mm×200 mm. The circuit board has 128 array of high speed readout electronics based on ASIC and FPGA. And it is divided into two parts:the middle area of high sensitive and the peripheral area of low sensitive. The two parts share a set of readout electronics. The experiment tests the position and the fine structure of the beam line produced by X ray machine in National Institute of Metrology. The results of the experimental show that the detector realizes both the spot tracing and the fine structure of the spot. The position resolution is 0.63 mm in x direction and 0.62 mm in y direction in high sensitive of the detector, which achieve the desired goal of preliminary design.