CVD金刚石辐射探测器研制及性能测试

电学性质优异的金刚石膜是理想的辐射探测器材料,用自支撑金刚石膜研制了辐射探测器,进行了探测器的性能测试.探测器采用的是"叉指"状共面型电极结构,探测器的有效探测区面积为3mm×3mm,探测器的连接接口是L16电缆头.探测器暗电流与电压呈线性变化的关系,表明金属电极与金刚石基底之间是欧姆型电接触.当两电极之间的电场场强为30kV/cm时,探测器的暗电流仅约为0·1nA,探测器信号的上升时间为590ps,探测器的灵敏度约110mA/W,而且探测器有较好的剂量率线性特性.     

同步辐射探测器的应用与发展

探测器是同步辐射实验的重要环节。探测器水平必须不断提高才能适应同步辐射发展的需求，最大限度地发挥先进光源为人类研究提供的强大支持作用。文章介绍了当前同步辐射实验中普遍使用的各种探测器的原理和特点，并就一些新型探测器的发展情况进行了阐述。     

同步辐射探测器的应用与发展

探测器是同步辐射实验的重要环节。探测器水平必须不断提高才能适应同步辐射发展的需求,最大限度地发挥先进光源为人类研究提供的强大支持作用。文章介绍了当前同步辐射实验中普遍使用的各种探测器的原理和特点,并就一些新型探测器的发展情况进行了阐述。     

Investigation of GEM-Micromegas detector on X-ray beam of synchrotron radiation

To reduce the discharge of the standard bulk Micromegas and GEM detectors, a GEM-Micromegas detector was developed at the Institute of High Energy Physics. Taking into account the advantages of the two detectors, one GEM foil was set as a preamplifier on the mesh of Micromegas in the structure and the GEM preamplification decreased the working voltage of Micromegas to significantly reduce the effect of the discharge. At the same gain, the spark probability of the GEM-Micromegas detector can be reduced to a factor 0.01 compared to the standard Micromegas detector, and an even higher gain could be obtained. This paper describes the performance of the X-ray beam detector that was studied at 1W2B Laboratory of Beijing Synchrotron Radiation Facility. Finally, the result of the energy resolution under various X-ray energies was given in different working gases. This indicates that the GEM-Micromegas detector has an energy response capability in an energy range from 6 keV to 20 keV and it could work better than the standard bulk-Micromegas.     

Investigation of GEM-Micromegas detector on X-ray beam of synchrotron radiation

To reduce the discharge of the standard bulk Micromegas and GEM detectors, a GEM-Micromegas detector was developed at the Institute of High Energy Physics. Taking into account the advantages of the two detectors, one GEM foil was set as a preamplifier on the mesh of Micromegas in the structure and the CEM pream- plification decreased the working voltage of Micromegas to significantly reduce the effect of the discharge. At the same gain, the spark probability of the GEM-Micromegas detector can be reduced to a factor 0.01 compared to the standard Micromegas detector, and an even higher gain could be obtained. This paper describes the performance of the X-ray beam detector that was studied at 1W2B Laboratory of Beijing Synchrotron Radiation Facility. Finally, the result of the energy resolution under various X-ray energies was given in different working gases. This indicates that the GEM-Micromegas detector has an energy response capability in an energy range from 6 keV to 20 keV and it could work better than the standard bulk-Micromegas.     

丝阵Z箍缩可见光辐射区径向变化过程

 在“强光一号”上进行的Z箍缩实验中,利用1维可见光成像系统获取了丝阵内爆可见光辐射区径向变化过程图像。采用的负载包括单层钨丝阵、单层铝丝阵,驱动电流为1.3~1.5 MA,上升时间89~140 ns。实验结果表明:丝阵内爆产生轴向先驱等离子体柱,尺寸为0.3~0.5 mm;丝阵在内爆和内爆到芯及冷却飞散阶段,外围区域始终存在较弱的可见光辐射;获得的可见光条纹像提供了丝阵等离子体内爆可见光轨迹,内爆径向压缩比为2.84～7.84,丝阵内爆速度为4.60×10⁶～1.73×10⁷ cm/s。     

碲锌镉面元辐射探测器堆积载流子屏蔽效应

采用铑(Rh)靶45 kV X射线源进行了碲锌镉(CdZnTe)面元像素阵列探测器成像实验。实验结果表明：在探测距离1 mm,管电压45 kV条件下,管电流增大至20 μA时,辐照中心区域像素单元信号丢失,出现围绕辐照中心区域的边缘高事件计数环形探测图像。随着管电流的增大,无响应像素区域扩大,探测器总体事件计数明显降低。进一步根据泊松方程建立了CdZnTe晶体内部电势分布模型,仿真结果表明：单位面积光子通量为5×105 mm-2·s-1时,由于CdZnTe晶体较低的空穴迁移率,晶体内部存在堆积空穴载流子形成的高空间电荷密度分布区域。晶体内部电场产生扭曲,电子载流子无法迁移至对应阳极位置,导致辐照中心区域产生信号屏蔽效应。     

碲锌镉面元辐射探测器堆积载流子屏蔽效应

 采用铑(Rh)靶45 kV X射线源进行了碲锌镉(CdZnTe)面元像素阵列探测器成像实验。实验结果表明：在探测距离1 mm,管电压45 kV条件下,管电流增大至20 μA时,辐照中心区域像素单元信号丢失,出现围绕辐照中心区域的边缘高事件计数环形探测图像。随着管电流的增大,无响应像素区域扩大,探测器总体事件计数明显降低。进一步根据泊松方程建立了CdZnTe晶体内部电势分布模型,仿真结果表明：单位面积光子通量为5×10⁵ mm^-2·s^-1时,由于CdZnTe晶体较低的空穴迁移率,晶体内部存在堆积空穴载流子形成的高空间电荷密度分布区域。晶体内部电场产生扭曲,电子载流子无法迁移至对应阳极位置,导致辐照中心区域产生信号屏蔽效应。     

Detection of accelerated particles from pulsed plasma discharge using solid state nuclear track detector

The ion beam of a Mather-type 23.25 J plasma focus device operated with air filling at 10 Torr was registered using CR-39 nuclear track detector. The irradiated samples were etched in NaOH solution at 70°C for 1 h. It is found here that plasm a beam contains multi-components of microbeams. The individual track density of microbeams is estimated and the total current density of the plasma stream is measured to be 1.2 mA/cm². A model for counting the track density of individual microbeams is proposed here. Faraday cup measurements showed the ion pulse with energy ranging from 5.8 keV to 3.3 keV.      

Plasma sprayed Al2O3/FeCrAl composite coatings for electromagnetic wave absorption application

Al₂O₃/FeCrAl composite coatings were fabricated by atmosphere plasma spraying technique. Microstructure and dielectric properties in the frequency range from 8.2 to 12.4 GHz were investigated. The microstructure of composite coatings shows a uniform dispersion of metal particles with litter pores and microcracks in the composite coatings. The relaxation polarization and interfacial polarization in the coatings would contribute to enhance ?′ with rising FeCrAl content, and the associated loss could be considered as a dominating factor enhancing ?″. By calculating the microwave-absorption as a single-layer absorber, for the composite coatings with 41 wt.% FeCrAl content, the reflection loss values exceeding −10 dB are achieved in the frequency range of 9.1-10.6 GHz when the coating thickness is 1.3 mm.     

Preparation of a silicon micro-strip nuclear radiation detector by a two-step annealing process

The annealing process for boron implantation is a crucial step during large size nuclear radiation detector fabrication. It can reduce the lattice defects and the projection straggling. A two-step annealing process for boron implantation was developed instead of a one-step annealing process, and the reverse body resistance of a silicon micro-strip detector was significantly increased, which means that the performance of the detector was improved.     

用于n,γ混合场的新型脉冲中子探测器研究

新型脉冲中子探测器采用特殊工艺将两个PIN半导体组合而成.利用脉冲γ辐射研究了探测器对γ的响应；利用脉冲中子源研究了探测器对DT中了的响应，并与闪烁探测器进行了比较 .结果表明：脉冲中子探测器对脉冲γ辐射基本不灵敏，对脉冲中子辐射的灵敏程度依赖于中子辐射体，是一种用于n，γ混合脉冲辐射场中子测量的新型探测器. 关键词： 硅半导体 差分补偿 脉冲中子探测器 n γ混合场     

Very low pressure plasma sprayed alumina and yttria-stabilized zirconia thin dense coatings using a modified transferred arc plasma torch

As a novel thermal spray process, very low pressure plasma spray (VLPPS) process has been significantly used to deposit thin, dense and homogenous ceramic coating materials for special application needs in recent years. In this study, in order to enhance low-energy plasma jet under very low pressure ambience, a home-made transferred arc nozzle was made and mounted on a low-power F100 plasma torch to fully melt or evaporate powder feedstock. As a result, thin and dense alumina (Al₂O₃) and yttria-stabilized zirconia (YSZ) ceramic coatings with an average thickness of 30-40 μm were successfully elaborated by the VLPPS process below 1 mbar. An optical emission spectroscopy (OES) was used to analyze the plasma jet properties. The microstructures of the coatings were observed by means of a scanning electron microscopy (SEM). It was found that the YSZ coatings displayed a bimodal microstructure which was composed of splats formed by melted particles and a little amount of vapor condensation from evaporated particles. However, vapor condensation could not be observed in the Al₂O₃ coatings, and only lamellar splats were found. The mechanical properties of both coatings were also evaluated.     

红外探测器三波段高通滤光片的研制

红外探测器在空间探测以及目标发现和跟踪技术中具有极为重要的应用,其性能的优劣直接关系到获取数据的准确性和可信性。为了提高红外信号的分析灵敏度,降低探测器的噪声,在（CVD）ZnS基底上,采用电子束及离子辅助沉积技术,研制了3 m～5 m高透、1.064 m～2.5 m波段截止的高通滤光膜。为了有效防止1.064 m波段处的激光对探测器造成的激光损伤,以保证探测器的正常工作,根据激光器的输出功率制备了对1.064 m激光波段具有1%,0.1%,0.01%数量级衰减能力的系列高通滤光膜,使红外探测器更具灵活性与智能化的特征。     

基于逆卷积神经网络的等离子体辐射分布断层重建方法

发展了一种基于逆卷积神经网络的图像级重建方法用于聚变等离子体辐射分布的断层反演.通过引入结构相似度(SSIM)作为损失函数,该方法在模拟数据实验中表现出了较好的重建效果.模拟实验结果表明,在弦积分信号噪声强度为10％、15％及20％时,该方法的重建结果依然具有良好的精确度和鲁棒性.     

Narrow-band model for nonequilibrium air plasma radiation

A band model is developed for the prediction of radiative transfer in air plasma applications under equilibrium and non-equilibrium conditions. For non-equilibrium applications, the medium is described by rotational–translational and vibrational temperatures but the populations of electronic states can be arbitrary. A specific formulation of the statistical narrow-band (SNB) model is developed for optically thick electronic systems of diatomic molecules when their populations are described by an electronic temperature. Model parameters, deduced from line by line calculations in the Voigt regime, are shown to be also convenient for arbitrary distribution of molecular electronic populations. This model is then complemented to include optically thin electronic systems and the continuum radiation through the simple box model, and line by line calculations for atomic lines. Several tests including equilibrium, non-equilibrium, uniform, and non-uniform conditions show the ability of this hybrid model to provide accurate and efficient solutions for radiative transfer problems in air plasmas.     

Study on the TU gas for the GEM-TPC detector

In this paper several different working gas mixtures for GEM-TPC were evaluated based on a Garfield simulation. Among them, Ar:CH4:CF4=90:7:3 (named herein TU gas) was selected for a detailed study because of its better performance. Some performances of drift velocity, transverse diffusion, spatial resolution and the effective number of electrons in various electric fields were obtained. The performance of a GEM-TPC prototype working in the TU gas was studied and compared with that in Ar:CH4=90:10 (P10 gas).     

Study on the TU gas for the GEM-TPC detector

In this paper several different working gas mixtures for GEM-TPC were evaluated based on a Garfield simulation. Among them, Ar：CH4：CF4=90：7：3 （named herein TU gas） was selected for a detailed study because of its better performance. Some performances of drift velocity, transverse diffusion, spatial resolution and the effective number of electrons in various electric fields were obtained. The performance of a GEM-TPC prototype working in the TU gas was studied and compared with that in Ar：CH4=90：10 （P10 gas）.     

CSNS多功能反射谱仪主探测器读出电子学系统研制

为满足中国散裂中子源（CSNS）多功能反射谱仪（MR）主探测器高气压³He多丝正比室探测器（MWPC）的需求,研制了专用的读出电子学系统。该系统主要由核心前放板和触发扇出板构成,其中以前放板为核心,采用了6块前放板实现探测器142路模拟信号的数字化,并通过判选机制甄别中子信息,将有效中子事例打包发送给后端,触发扇出板提供同一时刻到达的T0信号和触发信号,以确保数据的对齐。读出电子学系统分别在实验室和束流条件下,进行了相关指标测试,测试结果表明性能优于设计要求。目前MWPC探测器已经成功安装到MR谱仪现场,并且已经开始稳定运行。     

Silicon detector technology development in India for the participation in international experiments

A specific research and development program has been carried out by BARC in India to develop the technology for large area silicon strip detectors for application in nuclear and high energy physics experiments. These strip detectors will be used as pre-shower detector in the CMS experiment at LHC, CERN for π ⁰/λ rejection. The fabrication technology to produce silicon strip detectors with very good uniformity over a large area of ∼40 cm², low leakage currents of the order of 10 nA/cm² per strip and high breakdown voltage of >500 V has been developed by BARC. The production of detectors is already under way to deliver 1000 detector modules for the CMS and 90% production is completed. In this paper, research and development work carried out to develop the detector fabrication technology is briefly described. The performance of the silicon strip detectors produced in India is presented. The present status of the detector technology is discussed.