试验束测量中的气体阈式契仑科夫计数器

介绍了用于试验粒子束流中的电子选择的气体阈式契仑科夫计数器的研制,包括它的设计、加工安装和调试,并对其工作性能做了测量.采用CO₂作为辐射体,用XP2020Q光电倍增管记录契仑科夫光信号,测量给出对电子的选择效率约为(99.0±0.5)%.     

JLab Hall-A上小角度GDH实验中的粒子鉴别及其效率

在JLab的A大厅上的小角度GDH实验中, 因为散射截面及截面不对称度的测量需要干净的电子样本和足够的事例统计, 径迹在簇射量能器和气体阈契仑柯夫探测器理的信息被用来完成粒子鉴别的任务. 通过优化粒子在两种探测器里的信息筛选条件, 可以得到较高的电子接收效率和π的去除能力. 因为探测器的分辨能力与粒子的动量等运动学参量有关, 所以对于不同的数据的粒子鉴别条件分别进行了优化, 并得到了对应的电子接收效率和π的去除能力.     

宇宙线μ子的大气契仑柯夫光像

给出理想条件下聚光镜焦平面上单个μ子大气契仑柯夫光像的理论结果．简要地介绍在标定第二代大气契仑柯夫光成像望远镜中的应用．     

逆契仑柯夫聚焦激光电子加速器

本文提出逆契仑柯夫聚焦激光加速电子的基本原理。由粒子动力学分析表明,在满足契仑柯夫辐射条件下,可以对电子进行持续稳定的加速,而无需外加粒子聚焦系统。由于聚焦轴上激光电场就是加速电场,因此,它比已提出的逆契仑柯夫激光加速方案具有更高的加速场强。文中还指出这类加速机理的局限性。 关键词：     

2M阈式气体契仑科夫探测器

本文描述了为鉴别5—10GeV/c的π—K、K—P而研制的阈式气体契仑科夫探测器.速度分辨率达3.5×10^-5,对粒子的探测效率为99.99％,对阈能以下的粒子的排斥比为1.6×10^-5。     

1 MeV电子辐照对短波Hg1-xCdxTe光伏探测器的影响

 研究了1 MeV电子辐照对短波Hg_1-xCd_xTe光伏探测器的影响。通过测试电子辐照前后光伏探测器的响应光谱、信号、噪声、暗电流等性能参数，分析了电子辐照对Hg_xCdxTe光伏器件的影响机制。实验结果发现：电子辐照后器件响应光谱在短波处有变窄的趋势，但响应峰值波长和截止波长基本无变化；随着辐照剂量的增加，通过p-n结的暗电流有所增加，光伏器件的探测率有减小的趋势。     

50MeV/u 12C离子实验靶区出射中子角分布实验测量

本文用氟和碳阈探测器对50MeV/u ¹²C离子引起的重离子反应实验靶区E_n>11MeV和E_n>20MeV中子的角分布进行了实验测量,结果显示出明显的前冲分布,较高能量的中子具有更强的前冲趋势.     

光纤X射线探针和测量系统

利用Ｘ射线在探针中的康普顿散射以及电子在光纤中的契仑柯夫效应可以构成光纤Ｘ射线探针和测量系统，本文对此做了理论和实验研究，推导了光纤探针的灵敏度公式，给出了计算结果，并做了实验标定，讨论了光纤探针测量系统的构成，测量的动态范围和响应时间。     

252Cf自发裂变中高能γ射线的搜索

为了探寻超密核存在的可能性,用铅玻璃契仑柯夫全吸收谱仪在²⁵²Cf自发裂变中搜索高能γ射线。给出能量在50到240兆电子伏区域的γ射线出现几率的上限值为1.4×10^-6/裂变（置信水平95％）.     

波段外激光辐照光导型InSb探测器的一种新现象

利用不同功率密度的10.6 μm(光子能量为0.12 eV)连续激光辐照了禁带宽度为0.228 eV的光导型锑化铟探测器, 得到了与以往报道不同的实验现象. 当10.6 μm波段外激光辐照光导型探测器时, 探测器吸收激光能量后温度升高. 在探测器的温升过程中, 存在一个转变温度T₀. 当探测器的温度T<T₀时, 载流子浓度基本不变, 迁移率随温度的升高呈T^-2.35趋势下降, 引起探测器的电导率减小, 电阻增大, 响应输出电压升高; 当T>T₀时, 热激发载流子浓度随温度的升高呈指数增长, 电阻急剧下降, 超过了载流子迁移率降低对电阻的影响, 响应输出急剧下降. 光电导探测器在较高功率密度波段外激光辐照下的响应特性是载流子的浓度和迁移率在温度影响下相互作用的结果. 这对进一步完善半导体内载流子输运模型提供了实验依据.     

Simulation of natural radioactivity backgrounds in the JUNO central detector

The Jiangmen Underground Neutrino Observatory(JUNO) is an experiment proposed to determine the neutrino mass hierarchy and probe the fundamental properties of neutrino oscillation.The JUNO central detector is a spherical liquid scintillator detector with 20 kton fiducial mass.It is required to achieve a 3%/E(MeV)~(1/2) energy resolution with very low radioactive background,which is a big challenge to the detector design.In order to ensure the detector performance can meet the physics requirements,reliable detector simulation is necessary to provide useful information for the detector design.A simulation study of natural radioactivity backgrounds in the JUNO central detector has been performed to guide the detector design and set requirements for the radio-purity of the detector materials.The accidental background induced by natural radioactivity in the JUNO central detector is 1.1/day.The result is satisfied for the experiment.     

Dynamics of a charge qubit coupled with a double-dot detector

We investigate theoretically the dynamics of a charge qubit (double quantum dot system) coupled electrostatically with the double-dot detector. The qubit charge oscillations and the detector current are calculated using the equation of motion method for appropriate correlation functions. In order to find the best detector performance (i.e. the detector current signal follows as well as possible the qubit charge oscillations) we consider different qubit-detector geometries. The optimal setup was found for the qubit lying parallel to the detector quantum dots for which we observed very good detector performance together with weak decoherence of the system. It is also shown that the asymptotic detector current (flowing in response to the limited in time qubit-detector interaction) fully reproduces the qubit dynamics.     

An estimation of EDXRF spectrometer properties,based on a two‐layer composite Si‐Ge detector

A mathematical model for the two‐layer composite Si‐Ge energy dispersive X‐ray detector is proposed, based on analyses of radiation and electron transport in the detector, and a mathematical model of an energy dispersive X‐ray fluorescent spectrometer with the detector is considered. The Monte Carlo method is applied to calculate probabilities of photon detection in different parts of the detector's response function. The composite detector with the time anti‐coincidence scheme is proposed; its first layer is Si detector, and the second layer is Ge detector. It is shown that this composite detector has some advantages, such as reduced Ge photo escape peaks intensities and efficiency of detection of high energy photons similar to efficiency of Ge detector. Applying the X‐ray detector for the energy dispersive X‐ray fluorescent spectrometer provides for a lower background level. Copyright © 2012 John Wiley & Sons, Ltd.     

Dosimetric properties of the newly developed KLT-300 (LiF:Mg,Cu,Na,Si) TL detector

The dosimetric properties of the newly developed KLT-300 (KAERI LiF:Mg,Cu,Na,Si TL detector) in KAERI (Korea Atomic Energy Research Institute) were investigated. The sensitivity of the TL detector was about 30 times higher than that of the TLD-100 by light integration. In the study of the dose linearity of the detector, the dose response was very linear up to 10 Gy and a sublinear response was observed at higher doses. The energy response of the detector was studied for photon energies from 20 to 662 keV. The results show that a maximum response of 1.004 at 53 keV and a minimum response of 0.825 at 20 keV were observed. The reproducibility study for the TL detector was also carried out. The coefficients of variation for each detector separately did not exceed 0.016, and for all the 10 detectors collectively it was 0.0054. IEC Standard requires that the coefficient of variation shall not exceed 0.075. So, the reproducibility of this new TL detector sufficiently satisfied the IEC requirements. A detection threshold of the detector was investigated and found to be 70 nGy by Harshaw 4500 TLD Reader.     

用于辐射复合与双电子复合实验的低能离子闪烁探测器

为了在CSRm的电子冷却器上进行辐射复合以及双电子复合实验, 需要探测能量小于4 MeV/u的离子, 因此设计了新的置于超高真空环境的CsI(Tl)闪烁探测器, 探测器采用的光电倍增管为R7525(Hamamatsu）。 介绍了新闪烁探测器的结构, 并对其进行了性能测试。 测试结果表明, 该探测器对高、 低能离子均有良好的响应, 探测器的信号十分明显。 探测器的最高计数率可以达到106 ions/s, 并且探测器附近的真空度可达10-10 Pa量级, 能够满足辐射复合与双电子复合实验以及储存环对真空的要求, 为今后在CSRm上进行复合实验打下了良好的基础。 A new CsI(Tl) scintillation detector readout with R7525 PMT(Hamamatsu）is designed to detect low energy (<4 MeV/u) ions in radiative recombination and dielectronic recombination experiments at the main cooler storage ring in Lanzhou. The structure of the scintillator detector is described in this paper. The detector is tested with α source and ion beams, respectively. The signals from background, 200 MeV/u C6+ and alpha radioactive source are recorded and analyzed. The results show that the detector has good response to high and low energy ions. The maximum counting rate of the detector can reach 106 ions/s and the vacuum level near the detector can reach 10-10 Pa, both are good for recombination experiments. The installation of the new detector to CSRm is of great help for future radiative recombination and dielectronic recombination experiments.     

基于热释电探测器的重频脉冲激光诊断

摘以热释电探测器的工作原理为基础,研究了热释电探测器对重频脉冲激光的瞬态响应特性,建立了热释电探测器对单脉冲激光辐照响应的工作模型,分析了影响探测器频率特性的主要因素。根据材料和结构参数模拟计算了实际应用中的响应模型。设计了信号检测电路并对其进行计算仿事。完成了探测器的频率响应、脉宽响应等实验测量,验证了热释电探测器用于高重频、窄脉冲激光能量测量的可行性。     

红外探测器光谱响应度测试技术研究

光谱响应度是探测器的重要技术参数之一，随着红外探测技术的发展，精确测量红外探测器的光谱响应度变得越来越重要。首先对红外探测器光谱响应度的测试技术进行分析，然后建立红外探测器相对光谱响应度测量装置，并用腔体热释电探测器在该装置上进行红外探测器光谱响应度校准实验。通过对红外探测器相对光谱响应度进行重复测量，给出测量结果的平均值，最后对影响测量结果的不确定度进行分析。由于该装置的测量范围是1～20μm，因此还可以实现InSb探测器和HgCdTe探测器相对光谱响应度的测量。不确定度分析结果表明，InGaAs探测器光谱响应度的测量精度较高。     

Versatile wideband balanced detector for quantum optical homodyne tomography

We present a comprehensive theory and an easy to follow method for the design and construction of a wideband homodyne detector for time-domain quantum measurements. We show how one can evaluate the performance of a detector in a specific time-domain experiment based on the electronic spectral characteristic of that detector. We then present and characterize a high-performance detector constructed using inexpensive, commercially available components such as low-noise high-speed operational amplifiers and high-bandwidth photodiodes. Our detector shows linear behavior up to a level of over 13 dB clearance between shot noise and electronic noise, in the range from DC to 100 MHz. The detector can be used for measuring quantum optical field quadratures both in the continuous-wave and pulsed regimes with standard commercial mode-locked lasers.