A position-sensitive detector for electrons

A chevron electron multiplier array, followed by a resistive strip collector, has been combined with position-sensitive detector circuitry to provide a detector for particles or photons with position resolution of 0.3 mm in one dimension along a 2 cm strip; the instrument has been applied to a high resolution electron spectrometer. Position resolution appears to be limited only by the capillary spacing of the particular array being used.     

A position-sensitive wire-strip thermal- and cold-neutron detector with a boron converter

A position-sensitive wire-strip detector for thermal and cold neutrons is developed. The neutron converter is a 5-μm layer of ¹⁰B. Secondary α-particles are captured in a 1-mm gap of 73%Ar + 25% CO₂ + 2% SF₆ gas mixture at atmospheric pressure. The gas gain is ensured by an array of 20-μm wires of gold-coated tungsten.     

A variable angle photoelectron spectrometer using a position-sensitive detector

A variable angle photoelectron spectrometer utilizing a position-sensitive multidetector is described. Photoelectron spectra of N₂ obtained using a synchrotron radiation source are presented. The data are acquired using a new technique in which the photoelectron yield is obtained as a function of both wavelength and photoelectron energy, and this gives detailed information on autoionization processes.     

2维位置灵敏中子探测器读出

介绍了基于厚型气体电子倍增探测器(THGEM)的位置灵敏热中子探测器中,采用专用集成电路的阵列电荷灵敏前置放大和可编程器件的读出电子学设计。专用集成电路采用VA64TA2,64通道输入电荷灵敏放大成型,触发输出。控制电路使用了现场可编程器件。两者结合,显著减少了读出电路在探测器内所占据的空间。介绍了VA64TA2裸片的封装,给出了电路的原理和时序,进行了线性和电子学噪声试验,结果表明电路具有16 fC的线性动态范围,电子学噪声仅为75个电子电荷。     

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.     

Study of a position-sensitive scintillator neutron detector

The investigation of a novel thermal neutron detector is developed to fulfill the requirements of the high intensity power diffractometer (HIPD) at the Chinese Spallation Neutron Source (CSNS). It consists of two layers of ⁶LiF/ZnS(Ag) scintillators, two layers of crossed WLSF arrays, several multi-anode photo multiplier tubes (MA-PMT), and the matching readout electronics. The neutron detection efficiency of the scintilltors, the light transportation ability of the WLSF, and the spatial linearity of the readout electronics are measured and discussed in this paper. It shows that the sandwich structure and the compact readout electronics could fulfill the needs of the HIPD. A prototype with a 10 cm×10 cm sensitive area has been constructed to further study the characteristics of the neutron scintillator detector.     

极紫外位置灵敏阳极光子计数成像探测器研究

研制出了应用于月基极紫外成像仪的二维极紫外位置灵敏阳极光子计数成像探测器原形样机,该探测器主要由工作在脉冲计数模式下的微通道板堆、楔条形位置灵敏阳极及相关的模拟和数据处理电路组成。设计和制备了周期为1 mm,直径为30 mm的三电极楔条形位置灵敏阳极,研制了最高计数率为200 kHz的前端模拟和数字电路。测量了探测器的暗计数率、脉冲高度分布及空间分辨率等工作特性。测量结果表明,该探测器的空间分辨率为028 mm,满足月基极紫外成像仪对空间分辨率的要求。     

Improving linearity of position-sensitive detector using support vector machines

An intelligent method for improving position linearity of position-sensitive detector (PSD), based on support vector machines (SVMs), is developed. The SVM is established based on the structural risk minimization principle rather than minimizing the empirical error commonly implemented in neural networks.SVM can achieve higher generalization performance. Training SVM is equivalent to solving a linearly constrained quadratic programming problem, thus the solution of SVM is always unique and globally optimal.The improving position linearity procedure has been illustrated using a two-dimensional (2D) PSD. It is pointed out that the position linearity of the measuring system with a proper SVM correction is improved by two orders of magnitude in the measurement range.     

二维位置灵敏探测器输出图像畸变的修正

高分辨(e,2e)谱仪采用二维位置灵敏探测器同时对能量和角度进行多道测量.二维位置灵敏探测器由级联使用的微通道板和电阻阳极板组成,由于电阻阳极板的边缘效应和制造工艺的缺陷,测量得到的位置图像与实际图像总会有一定的形变,存在一定的非线性.本文针对高分辨(e,2e)谱仪二维位置灵敏探测器输出图像的“桶形”畸变及位置非线性,采用一种简易的冷刻法(用脉冲信号来模拟真实电子束团),检验了二维位置灵敏探测器的Gear型电阻阳极板的线性好坏,并用分割成小三角形的方法找出测量得到的畸变图像与原始真实图像的映射关系,再用此关系对其它测量得到的畸变图像进行修正,并对修正的结果进行了评估.通过修正,由“桶形”畸变所造成的图像扭曲得到明显改善.修正后的x方向非线性由修正前的2.1%变为0.59%.这种检验和修正方法对其它领域类似探测器输出图像的修正也有一定的指导意义.     

High pressure,high resolution synchrotron x-ray powder diffraction with a position-sensitive detector

Abstract

We report results of high-pressure experiments with a new diamond-anvil cell in a monochromatic, high-resolution x-ray scattering geometry with alinear position-sensitive detector. The experiments make possible the study of factors controlling line widths of diffraction profiles at pressures in the 100 GPa range, and demonstrate the potential for the use of line profile analysis and Rietveld refinement techniques with high-pressure powder diffraction data. Combined data for various materials indicate that relative contributions to linewidths due to particle size, intrinsic material strength, pressure and state of stress in the sample can be resolved. With light rare-gas solids as pressure-transmitting media, measured FWHMs of the order 0.03? 2 θ corresponding to resolution Δd/d of 2.5 × 10^?3 for 2θ～10-15? are reported. Formation of a high pressure phase appears to involve growth of submicron domains, judging from substantially broadened diffraction peaks under quasihydrostatic conditions. Detailed analysis of complex, non-quenchable high-pressure phases will likely require annealing techniques such as thermal cycling at pressure.

Presented at the IUCr Workshop on ‘Synchrotron Radiation Instrumentation for High Pressure Crystallography’, Daresbury Laboratory 20-21 July 1991     

使用曲面微通道板和感应电荷位置灵敏阳极的软X射线-极紫外光子计数成像探测器研究

本项目对我国空间探测的极紫外(EUV)波段大视场相机所需求的球面光子计数成像探测器的关键技术进行了研究。首先,建立了光阴极材料次级电子产出模型,利用该模型计算了软X射线-EUV波段常用的光电阴极材料—碱卤化物的次级电子产出,分析了微通道板(MCP)的次级电子产出。建立了测量MCP量子探测效率的装置,并推导出MCP量子探测效率的计算公式,测量了MCP在软X射线-EUV波段的量子效率以及MCP量子效率随掠入射角的变化。其次,建立了球面实芯微通道板的制备装置,利用高温热成型方法制备出曲率半径为150 mm球面MCP,利用光刻技术制备出有效直径为48 mm的楔条形感应电荷位置灵敏阳极,在此基础上集成了一套使用球面MCP和感应电荷位置灵敏阳极的两维光子计数成像探测器。再次,研制出包括快速前端模拟电路与后续数字电路的成像读出电路,编制了能矫正图像畸变的图像实时采集和处理软件。最后,建立了MCP探测器空间分辨率、图像线性的检测装置,对研制出的探测器性能进行了检测,检测结果表明:探测器的各项技术指标完全满足要求。     

Method for recording of solar neutrinos with a lithium detector

A method for solar neutrino recording on a laboratory bench with a lithium detector is developed. The efficiency of extraction of beryllium from lithium as high as 96.4% is achieved, and it is shown that lithium extraction losses are less than 1%. The results of a full-scale experiment with a 10-t lithium detector consisting of 20 500-kg modules are presented. Technical solutions based on the experimental results open the way to designing a pilot facility intended for 500 kg of lithium.     

Induced charge signal of a glass RPC detector

A gas detector glass resistivity plate chamber (GRPC) is proposed for use in the hadron calorimeter (HCAL). The read-out system is based on a semi-digital system and, therefore, the charge information from GRPC is needed. To better understand the charge that comes out from the GRPC, we started from a cosmic ray test to get the charge distribution. We then studied the induced charge distribution on the collection pad. After successfully comparing it with the prototype beam test data at CERN (European Council for Nuclear Research), the process was finally implanted into the Geant4 based simulation for future study.     

Luminescence of doped lithium tetraborate single crystals and glass

Lithium tetraborate single crystal doped with Cu seems to be a promising new material for neutron detection. With the presence of Li and B, both having large cross section for neutron capture, efficient neutron detection is expected with high-energy deposits. In the present work, we chose 14 different dopants from Ia, Ib, IIIa, IVa and Va groups in the periodic table besides the rare earth Ce ion. The crystals were grown to a size of 20 mm in diameter and 70 mm in length by vertical Bridgman method. The grown crystals were characterized by optical transmittance and excitation–emission studies. Transmittance and emission characteristics of Ce-doped lithium borate glass are also reported.     

A novel disk-type X-ray area imaging detector using radiophotoluminescence in silver-activated phosphate glass

We report a novel two- and three-dimensional (2-D, 3-D) imaging detector based on the radiophotoluminescence (RPL) phenomenon in silver-activated phosphate glass (PG:Ag) and evaluate its dosimetric characteristics. A compact disk-type PG:Ag detector with a diameter of 80 mm was rotated at a rate of 400 rpm to read out the accumulated dose information and then remove the images for reuse. After X-ray exposure, three RPL dosimeter processes, i.e., preheating, reading, and erasing, were carried out with only a UV laser at 375 nm by adjusting the stepwise output levels. The 3-D images and dose distributions were rapidly reconstructed with a high spatial resolution of 1 μm and a sensitivity of 1 mGy.