国际计量技术联合会第十届光子探测器学术讨论会

国际计量技术联合会(IMEKO)第十届光子探测器学术讨论会于1982年9月20～22日在西柏林举行,来自20个国家的一百多位科学家参加了会议。 会上宣读了40篇论文,涉及到光子探测器的物理性能及其在各方面的应用。大致有:雪崩二极管在单光子计数方面的应用,GaAs、CdSe、Ge光子探测器性能的研究,硅在紫外区的量子产额,光电倍增管、硅光二极管、成象光子计数系统的直线性研究,集成电路中的光子探测器,硅光二极管的自校准技术,基于     

光子被光子散射证据首次找到

正据报道,欧洲核子中心(CERN)的ATLAS探测器中,发现了高能量下光子被光子散射的首个直接证据。这一过程极为罕见,两个光子相互作用并改变了方向,这证实了量子电动力学的最早预测之一。ATLAS探测器项目物理协调员丹·托沃里说:"这是里程碑式的成果,是光在高能量下自身相互作用的第一个直接     

焦平面红外探测器研究进展

红外探测器在当今社会具有不可替代的作用。本文简要介绍了红外探测器的发展,对目前几种常用光子型焦平面红外探测器进行了比较;介绍了焦平面红外探测器在军事领域的需求及应用,介绍了国内外焦平面红外探测器研究现状,对几种典型的探测器性能做了比较;讨论了焦平面红外探测器存在的问题,对其成像非均匀性做了简要分析,总结了焦平面红外探测器发展趋势。     

基于PET的探测器技术的研究与探讨

正电子发射断层扫描技术是目前应用于临床诊断的先进的医学断层成像,尤其是对于心脏病、肿瘤以及脑部疾病的诊断。文章对于PET的概念、工作原理以及其临床应用方面都做出了一定的介绍。PET系统的关键部位是其探测器,并且文章也对探测器接收到的γ光子进行数据处理,制出散点图观察γ光子的分布。根据散点图可知,γ光子的分布并不均匀。PET的成像存在着一定的误差,所以需要对数据进行校正,随着PET的发展,新型探测器技术也需要不断的研究与改善。     

单光子同步探测中的后脉冲特性分析

本文对单光子探测过程中后脉冲特性进行了理论分析,通过实验对后脉冲概率进行了统计测量,研究发现单光子探测器存在两个电子俘获能级,寿命分别为503 ns和33 ns.研究讨论了同步探测单光子对后脉冲的抑制.     

EUV波段光子计数成像探测器信息处理器的设计与实现

EUV波段光子计数成像探测器通过对30.4nm的He+共振散射分布进行成像,从而对地球等离子体层的分布进行研究。信息处理器是EUV波段光子计数成像探测器的核心部分,利用FPGA进行信息处理器的设计,从而完成对图像信号的放大、整形、保持、量化、采集和传输等重要功能控制,空间分辨率达到0.28mm。     

上海微系统所成功研制微纳光纤耦合超导纳米线单光子探测器仪表研发

<正>超导纳米线单光子探测器(SNSPD:Superconducting nanowire single-photon detector)作为一种高性能的单光子探测器,已广泛应用于量子信息、激光雷达、深空通信等领域,有力推动了相关领域的科技发展。SNSPD器件主要有两种光耦合方式,一种是垂直光耦合方式,光纤端面平行于SNSPD光敏面,光子垂直入射到纳米线上,采用光学腔体或反射镜     

CdTe探测器能量刻度与探测效率的模拟计算

在实现对单能平行光子源的绝对测量之前,需要对CdTe探测器进行刻度。利用已知点源对CdTe探测器进行能量刻度,得到刻度曲线和能量分辨率,利用工业CT对CdTe探测器进行精确扫描,得到CdTe探测器内部结构,并以此为基础,利用MCNP5蒙特卡罗模拟程序建立CdTe探测器物理模型;计算20～150keV能量段,能量间隔为1keV每个能量点的探测效率,得到CdTe探测器的效率曲线图。发现CdTe探测器在低能段探测效率较高,但Te元素在27keV和32keV处产生了逃逸峰,探测效率有所下降,之后探测效率曲线呈现先上升后下降的趋势。     

基于Geant4的高纯锗探测器模拟

该文利用蒙特卡罗程序包Geant4构建了高纯锗探测器的实际结构,模拟了γ射线在高纯锗探测器中与材料发生的相互作用。通过统计光子在高纯锗探测器中的能量沉积,累计得到4种能量射线的能谱,并通过拟合公式对能谱进行展宽,模拟实际能谱。将模拟得到的能谱结果与高纯锗探测器探测到的实际能谱进行对比,比较模拟能谱和实际能谱的全能峰、统计效率和半峰宽,验证了分辨刻度系数在实际模拟中的可行性,为进一步进行高纯锗探测器的模拟实验提供了技术支持。     

反光电子谱仪的研制

用经过改进的LEED装置和自制的9.8eV光子探测器研制成反光电子谱仪。测得了Si(111)7×7清洁表面的反光电子谱。     

An orthogonal peak detector for multiphase sinusoidal signals

A novel sinusoidal amplitude detector is proposed. This detector is based on the characteristic of orthogonal pairs. The salient point of this algorithm is that it can be applied in multiphase systems. The transient performance of this detector is very good, due to its fast response characteristic. The proposed detector is implemented and tested in three multiphase systems to verify its performance     

Analytic beam spread function for ocean optics applications

A discrete ordinates code is developed with which to compute the beam spread function (BSF) without invoking the small-angle scattering approximation or performing Monte Carlo calculations. The computed BSF is used to predict the response of a detector versus its distance to the origin of a highly collimated beam, its angle with respect to the beam, and the two local angles that specify the detector orientation. Numerical results have been obtained for water models that simulate a clear ocean, a coastal ocean, and a turbid harbor. Six orders of magnitude or more change in the detector response caused by scattered photons can be predicted for different detector locations while simultaneously obtaining small changes for different detector orientations. This capability is useful for assessment of the sensitivity of the detector response to the interpretation of time-independent underwater imaging systems or visibility models.     

Signal space detection in colored noise

An appropriate adaption of the decision boundaries of the well-known signal space detector (SSD) yields a detector that whitens the input noise in the detector forward path. This new detector, called a whitening signal space detector (WSSD), offers higher reliability without increasing the dimensionality of the signal space. A WSSD can be designed by applying a transformation into the ordinary SSD case. We use the new concept to design a WSSD based on three-dimensional 110 equalization and demonstrate its feasibility and performance. The detector can be implemented with a small increase of hardware and offers a significant improvement in terms of bit error rate, especially at low to moderate channel densities     

Miniature triaxial metastable ionization detector for gas chromatographic trace analysis of extraterrestrial volatiles

Gas chromatography has found highly successful application in NASA's flight programs. Gas chromatographs have been flown to both Mars and Venus where detailed compositional measurements were made. These instruments were quite small and relatively sensitive when compared to commercially available instruments; however, they do not appear adequate for future missions currently being planned. The earlier flight GC's had incorporated thermistor bead thermal conductivity cells as the detector. This detector requires very precise temperature control and only provides about 1 ppm sensitivity. Temperature stabilization causes the detector to be quite heavy, i.e., about 200 g. Greater sensitivity will be required for measurements of trace components in extraterrestrial environments. Review of other detector types revealed the metastable ionization detector as a likely candidate because of its superior thermal stability and high sensitivity. The metastable detector, first described by Lovelock as an argon ionization detector, has been studied and somewhat modified by others. The commercial design by Hartmann and Dimick was used for comparison purposes in our work. In the past, three features of the metastable detector are prominent: it has part-per-billion sensitivity, contamination must be carefully controlled, and anomalous response is common. Since it is an ionization detector, however, temperature instabilities do not cause the major perturbations experienced by the thermal conductivity detectors. This paper describes a miniature metastable ionization detector featuring an unconventional electrode configuration, whose performance characteristics parallel those of traditional design, while its weight is quite small. The prototype has been used in our laboratories routinely for 2 years, and the concept will be incorporated into a flight GC for use in the Space Shuttle.     

氩放电检测器气相色谱仪在高纯氩气检测中的应用

氩放电检测器(Argon Discharge Detector)是一种用氩气做载气的气相色谱仪专用检测器,因其具有独特的检测能力,在氩气检测领域应用较为广泛。采用AGC仪器公司生产的Nova CHROM2000搭载氩放电检测器(ADD)气相色谱仪,对该检测器的检测能力进行评测。     

Detector effects in photothermal deflection experiments

We report on the theoretical analysis of a detector type influence on the normal deflection signal in photothermal experiments. Two cases are examined. In the first, the quadrant photodiode was considered as the detector; in the second the signal from the position detector, which measures the central moment displacement of the probe beam, was analyzed. Both analyses were carried out within the framework of the complex ray theory. The normal photodeflection signal was found to depend on the type of detector used in the photothermal deflection experiments for some parameters of its setup.     

Turbulence as a source of excessive baseline noise during high-speed isocratic and gradient separations using absorption detection

The occurrence of turbulent flow conditions in the connection tubing or at the entrance of the detection flow cell has been identified as a potential source of excessive detector noise in the signal of the diode array UV-absorption detector flow cell of a commercial HPLC system used to perform high-speed separations on wide-bore columns (4.6 mm i.d.). This excessive noise was found to occur abruptly if the flow rate is increased beyond a certain critical value or during gradient runs, if the mobile phase viscosity falls below a certain critical value. Several detector cells of different dimensions were studied to investigate the dependency of the effect on the detector cell design and the system tubing. Evidence for the turbulent flow origin of this noise is that its onset always occurred at a given fixed value of the Reynolds number. This critical Reynolds number could also be used to predict the onset of detector noise during gradient elution runs. Second, evidence for the turbulent flow origin of the noise was that it could be reliably eliminated using a flow splitter after the column to reduce the flow rate below its critical value before entering the detector. The loss in separation efficiency and detection sensitivity accompanying this flow splitting solution was found to be so small that it does not weigh up against the huge advantage of the possibility to eliminate the excessive detector noise.     

Characteristics of highly sensitive terahertz wave detector based on lithium niobate

The characteristics of a highly sensitive terahertz wave detector based on lithium niobate have been investigated using a steady-state theory. The contributions of the low-frequency modes to the dielectric constant of lithium niobate are considered. The intrinsic factors of the LN detector limit its high frequency response to about 4?THz. Temperature dependence of the detector from room temperature to 250°C was also studied. The main factors associated with the temperature variations of the sensitivity of the detector are thermal expansion, the nonlinear coefficient and the refractive index of the crystal. The nonlinear coefficient dominates the temperature dependence of the sensitivity of the detector, while the impact of the refractive indices of the near-infrared lights on the temperature variation of the sensitivity of the detector is negligible. This study provides a useful guide and a theoretical basis for the further improvement of the detection systems.     

An ultrasonic obstacle detector based on phase beamforming principles

A prototype of an ultrasonic obstacle detector developed as a part of a navigation system for blind and visually impaired people is presented. The detector, which employs a single ultrasound source and an array of microphones, determines the distance to the obstacle by measuring time between sending the pulse and receiving the reflected signal. Using the phase beamforming technique, borrowed from hydroacoustics, to process the output signals of microphones, it determines also the direction from which the reflected signal is received, thereby locating the obstacle. The obstacle detector was subjected to a series of tests in order to verify its design and to assess its ability to detect a broad range of obstacles. Presented test results show that most obstacles can be detected and recognized, and that the tested obstacle detector provides complete coverage of the safety zone in front of the user.     

用于空间辐射环境探测的金刚石探测器研究综述

空间辐射环境探测可减轻或避免辐射环境对航天器和宇航员的危害,已成为近年来各航天大国研究空间环境的热点.对空间辐射环境进行探测的探测器较多,包括气体探测器、闪烁体探测器和半导体探测器,半导体探测器具有能量分辨率高、探测效率高等优点,已逐渐取代其他两种探测器.金刚石辐射探测器是半导体探测器的一种,具有探测精度高、耐候性好、无需制冷、寿命长以及抗辐射能力强等优点,特别适合长周期、强辐射的深空探测.同时,金刚石禁带宽度大,不响应可见光,可实现日盲观测,已被欧洲空间局(ESA)用于太阳紫外辐射探测.俄罗斯工业技术中心在多种粒子复合探测方面正在研制宇宙射线光谱仪,尽管探测能区集中在中高能,但该光谱仪可实现电子、质子和重粒子的复合探测.基于目前金刚石辐射探测器在单粒子辐射探测中的应用及空间复杂的多种粒子辐射环境,我国的空间辐射环境探测研究应通过设计基于多层金刚石膜的单粒子辐射探测器来提高探测器的能量分辨率,再构建探测器矩阵进行多种粒子复合探测,将人工神经网络算法引入数据处理过程,以拓展探测范围到低能区,实现全能量范围粒子的探测,从而为开展金刚石探测器在空间站、深空辐射环境探测等领域的应用探索奠定基础.