Development of a transparent single-grid-type micro-strip gas chamber based on LCD technology

The liquid crystal display (LCD) technology allows several simple circuits to be built using thin film transistors, thus making fabrication of compact, integrated, large-area, and low-cost micro-pattern gaseous detectors possible. In this work, a single-grid-type micro-strip gas chamber (S-MSGC) using transparent electrodes based on the LCD technology was fabricated and successfully operated in several gas mixtures. The detector was coupled with a multi-pixel photon counter to detect an optical signal through the transparent substrate in Ar/CF₄ gas. Both electrical and optical signals were measured and the light yield of the detector was acquired. Successful operation of the S-MSGC can be considered the very important first step for development of the next target of integrated devices.     

大面积阵列中子伽马甄别探测器的蒙特卡罗模拟研究

对特殊核材料的检测关乎国土安全,需要一个快速、安全可靠的辐射检测系统。采用Geant4蒙特卡罗模拟软件建立一套基于塑料闪烁体的大面积中子伽马探测系统。研究单根闪烁体晶体不同截面边长、多种层数结构以及不同natGd₂O₃包裹方式等探测器的关键参数,通过调整探测器的响应数目阈值评估探测器的n/γ甄别性能。结果表明,当采用截面边长为6 cm×6 cm的塑料闪烁体包裹25 μm厚的natGd₂O₃、探测器之间放置3 mm厚Pb板以及探测器响应数目阈值设置为3时,阵列探测器可以达到约23%的中子探测效率以及约802的n/γ甄别比。计算结果可对大面积阵列探测器的关键参数优化提供理论依据。     

使用活化探测器和成像盘技术相结合的方法测量混凝土屏蔽体内中子空间分布

描述了一种联合使用活化探测器和成像盘技术（IP）探测中子注量的方法。利用这种方法测量了高能中子束线装置KENS（KEKspallationneutronsourcefacility）中混凝土屏蔽体内中子的空间分布。高能中子注量衰减的实验结果与使用蒙特卡罗程序MARS14模拟计算的结果符合很好。结果表明，联合使用活化探测器和成像盘技术可以同时测量多个位置的中子注量，直观展现出混凝土屏蔽体内中子强度的分布情况。     

CsI(Na)闪烁薄膜对重带电粒子时间响应实验研究

为发展具有粒子甄别能力的空间带电粒子辐射场测量的闪烁探测技术,本文采用单光子计数方法测量了片状CsI(Na)晶体在质子、锂离子和氧离子激发下的衰减时间曲线,结合CsI(Na)对脉冲X射线瞬态响应的波形分析,结果表明,CsI(Na)晶体对质子、重带电粒子和电子展示出完全不同的衰减时间特征。基于CsI(Na)材料的闪烁探测器在电流型计数模式下可望实现对高能电子、质子和重离子的分辨,从而为其用于空间辐射场测量的信号波形甄别奠定基础。     

Dosimeter characteristics of neutron track detectors used on high-energy accelerators

Conclusions Experience gathered in recording neutrons with the aid of polymer track detectors on calibrated neutron sources and around the 70 GeV proton synchrotron has shown that detectors making use of fissile nuclides in combination with polyethylene terephthalate track detectors and spark counting of the tracks are suitable and promising for their large scale use as measuring means of dosimetric characteristics of the neutron fields in a high-energy accelerator. They can be used to build an albedo-track dosimeter in which²³⁵U is the albedo detector and²³⁷Np,²³⁸U, and²³²Th are used as the threshold detector. Also a nitrate cellulose film without a converter can be used as a threshold detector but there the measurement error is 2–3 times greater than in the detectors making use of fissile nuclides because the film sensitivity has a considerable (30%) spread even to monochromatic neutrons. In addition, a detector based on²⁰⁹Bi can be used for spectrometric measurements of high-energy neutron spectra.The results of the present work will be of interest for an experimental verification of methods used to calculate the dose-dependent sensitivity of fissile-nuclide detectors and to develop promising types of personnel dosimeters.Translated from Atomnaya Énergiya, Vol. 69, No. 3, pp. 167–171, September, 1990.     

一种新型气体探测器的研制

加速器质谱(accelerator mass spectrometry,AMS)技术因探测对象不同,探测器也应根据需要进行选择。为建立低能量重离子加速器质谱测量技术,本文设计制作一台新型气体探测器并调试应用。该探测器采用厚度50 nm,膜面积8 mm×8 mm的氮化硅膜作为入射窗。采用5.48 MeV的241Am源的α粒子对探测器进行调试,调试后将该探测器安装于中国原子能科学研究院的300 kV小型AMS系统上进行129I粒子测量。经模拟计算以及对探测器的调试、应用,证明该探测器具有较高的能量分辨率,可以很好的实现不同粒子的鉴别,同时测量灵敏度可达到10^-13国际水平,满足低能量重离子的测量要求。     

Detection of prompt luminescence from an imaging plate with heavyparticle injection

We have been investigating the basic characteristics of an imaging plate JP) to develop a new type of ultra-heavy-particle detector. To acquire the information on the deposited energy, photostimulated luminescence (PSL) from the injection position is usually utilized, which occurs upon scanning the surface of the IP with a laser beam after the exposure of particles. However, in the use of PSL, there is the disadvantage that it fades with time. On the other hand, when heavy particles are injected to the IP, prompt luminescence (PL) also occurs from the injection position. We have succeeded in detecting the prompt luminescence from each heavy particle with the energy of several hundred MeV/n. Since the PL is useful for quick detection of the injection position, the PSL data can be read within a few seconds by scanning the determined position before any serious fading effect occurs     

Development of a time-of-flight spectrometer at the Ruder Boškovi? Institute in Zagreb

A new TOF telescope has been constructed for thin film and surface analysis. The timing system consists of two electrostatic mirror type detectors of Busch design. The detection efficiency of timing stations for very light ions was significantly improved using DLC (diamond like carbon) foils coated with LiF instead of the conventionally used carbon foils. Ion energy is measured by a 300 mm² ULTRA ion-implanted silicon detector. For the ERDA measurements with heavy and energetic ion beams, a time-of-flight (TOF) spectrometer is positioned at 37.5°. Spectrometer can be easily moved to 120° backward angle for time-of-flight RBS analysis with low energy beam of light ions. Positioning and fine adjustments of sample orientation are performed with a motorized sample stage. The same spectrometer can be also installed at the ion microprobe scattering chamber for 3D elemental imaging.     

应用于气体电子倍增器的电子学板研制

气体电子倍增器（GEM）电子学板（GEB）在大面积GEM探测器系统中起重要作用。为满足大面积GEM探测器系统中高速电子学信号的传输、实现电磁屏蔽及为前端电子学提供电源等需求,本文设计了8层结构的GEB,并对该GEB原型进行了电气性能、机械兼容性、信号传输和噪声测试。测试结果显示,本文所设计的GEB在320 Mb/s信号传输速度下的误码率小于10^-13,在保证信号高速性和完整性的基础上能成功传输前端电子学信号;通过采用叠层对称式设计克服了大面积GEB生产时弯曲程度高的困难,生产的GEB原型弯曲高度降低了2/3,平均弯曲高度为1 mm,增强了前端电子学在探测器系统中的运行稳定性。     

用成像板探测正电子

用成像板对常用正电子源＾３２Ｎａ进行了一系列感光实验。结果显示,激发辐射的光子强度值ｆ（ｐ）与成像板记记载的正电子流强ｆ（ｅ＾＋）成正比关系。在北京慢正电子束设备上进行了单慢正电子的感光实验,结果表明,成像板是慢正电子的一种优良的二维位置灵敏探测器。     

基于伴随粒子的快中子成像系统角分辨研究

不同于传统的快中子成像系统,采用伴随粒子成像技术无需机械准直即可消除大部分γ射线和散射中子的干扰,实现对厚重物体的高对比度成像。角分辨是影响系统成像质量的一项重要参数。通过理论分析,研究了入射离子的初始动量、靶点尺寸和探测器空间分辨等多个因素对系统角分辨的影响。利用基于GEANT4的模拟程序,计算了不同参数下被标记中子出射角分布的二维图像。分析及模拟结果表明,靶点直径和α探测器空间分辨率是影响角分辨的重要因素。为满足系统角分辨小于1°的设计目标,入射离子的初始动量变化范围应较小,靶点直径应小于1 mm,同时α探测器的空间分辨率应小于0.5 mm。     

核电站现场空气样品γ谱快速筛选测量

NaI（Tl）γ谱仪能量分辨率较差,不适合做精确的核素分析,特别是在样品中存在多种γ放射性核素时,各种核素的γ全能峰相互干扰,使确定样品中的核素种类以及定量分析核素的含量非常困难。但NaI（Tl）探测器的探测效率比较高,适合对大量样品进行快速筛选性测量。本文结合对某核现场气载放射性核素浓度进行普查的结果,介绍了使用NaI（Tl）γ谱仪对γ放射性样品进行快速筛选测量的方法。实际应用结果表明,快速筛选测量方法可以在测量时间较短的情况下,对含有一定量γ放射性核素的样品作出有效的筛选判断。     

成像板对X射线的能量响应

作为X射线探测器,成像板的光激发光子信号对X射线的能量响应是非常重要的数据。利用同步辐射光源的单能X射线照射成像板,得到成像板对低能光子的能量响应曲线,并与MCNP程序计算结果进行对比分析,得到成像板响应函数的衰减模型。计算结果与实验结果一致,为进一步开展成像板在辐射测量领域的研究工作提供了参考。     

A RPC test station based on ROOT and VME

Due to its advantages in large-area application situations, the RD of the resistive plate chamber(RPC)has always been carried out. A performance test station for RPC RD has been designed and developed based on the VME bus and ROOT in Linux. This system can be customized expediently according to the requirements of different tests, which facilitates detector RD because of its automatic HV scan, especially for long-term test. With this system, we have implemented the RPC performance test,including the efficiency curve, counting rate, dark current and charge and timing resolution.     

基于平板型闪烁晶体成像探测器位置刻度系统

对于通过准直方式成像的γ相机，因其闪烁体、位置灵敏光电倍增管（PSPMT）光阴极均具有一定的厚度，以及通过重心法计算位置的方式等原因，造成了γ相机在不对所成图像进行修正的情况下，这些γ图像向中心压缩，即出现边沿压缩效应。为减少和修正边沿压缩效应，本文设计了一套刻度系统。该系统采用逐点扫描探测器表面的办法，获得平板型探测器有效区域内所扫点位置与探测器响应位置的原始信息，得到进入探测器的光子的真实位置与γ相机电路输出信息之间的关系映射，形成用于还原每个进入γ相机有效区域内γ光子的实际位置的查找表，从而有效解决了γ相机成像时无法避免的边沿压缩效应造成的图像畸变。该系统在刻度过程中无需人工干预，自动生成位置查找表，为γ相机小孔成像的图像还原或编码孔成像的图像重建提供了必要条件。     

研究微剂量学的Q型计数器

探讨了在纳米量级研究重离子微量剂量学的重要性，在此基础上建立了一套研究重离子微剂量学的实验装置。它包括探测器，可远距离遥控的高精度三维微动装置，足够大的靶室系统，可对工作气体的气压进行测量和调节的气压稳定系统以及进行电离分布研究的电子学系统。     

Determination of the detection limit of Ni at the Lund AMS facility by using characteristic projectile X-rays

Accelerator mass spectrometry (AMS) is an ultra-sensitive method for counting atoms, both radionuclides and stable nuclides. When using small tandem accelerators to measure heavy isotopes, interfering isobars are often troublesome. One way to reduce this interference is to combine AMS with the detection of characteristic X-rays of the projectile. After analysis in the AMS system it is possible to identify ions of different atomic number by their characteristic X-rays, by slowing down the ions in a suitable target. In this paper, the detection limit of ⁵⁹Ni at the Lund AMS facility is reported. A method for the chemical extraction of nickel from stainless steel, combined with a purification step to reduce the cobalt content in the sample by several orders of magnitude, is also described.     

一种基于~(103)Rh(n,n′)~(103)Rh~m反应的快中子注量监测方法

给出了一种基于~(103)Rh(n,n′)~(103)Rh~m反应监测快中子注量的方法。根据干扰核素半衰期不同的特点,选取合适的冷却和测量时间,降低了~(103)Rh(n,n′)~(103)Rh~m活化率测量中干扰核素的影响。根据152Eu标定实验结果,利用遗传算法优化探测器尺寸,建立探测器蒙特卡罗算法模型。利用模型校正~(99)Mo-~(99)Tcm放射源实验效率,解决了探测器效率标定和射线自吸收问题。开展了快中子注量监测,实验结果与铁、硫、镍等快中子监测箔一致性较好,测量不确定度约为13.1%。     

塑料闪烁光纤阵列探测器研制及验证

为解决污染土壤中90Sr的快速、直接测定难题,研制了塑料闪烁光纤阵列探测器,通过塑料闪烁光纤空间排布设计、多路信号分析逻辑设定,实现从β、γ及宇宙射线信号中甄别出90Sr 90Y衰变的β射线信号,完成了土壤中90Sr的直接测量。探测器本底计数率为198 s-1,90Sr探测效率为14%,最小可探测活度为018 Bq/g（5 min）,测量净计数率与参考土壤90Sr比活度呈线性关系,拟合优度为0999。测量了极低放污染土壤,通过添加定量的90Sr再次测量方式对结果进行验证,测量值与参考值符合较好。塑料闪烁光纤阵列探测器测量速度快、准确度高,可用于核设施退役、环境普查等大规模土壤样品90Sr快速、直接测定。