微波脉宽对检波器性能影响的实验研究

 采用脉宽20~120 ns、步长10 ns的微波信号，对WB-CD01型、2087-6001-00型同轴检波器的灵敏度和检波波形进行了实验研究。实验结果表明：脉宽为20~120 ns时，在2.7 GHz频率下，WB-CD01型检波器灵敏度比连续波时的降低0.5~0.7 dB，而2087-6001-00型检波器灵敏度比连续波时的降低近1 dB。在4.1 GHz频率下，WB-CD01型检波器在微波脉宽为20 ns时，检波灵敏度略高于连续波时的近0.2 dB，其它给定脉宽下，检波灵敏度与连续波时的基本一致；2087-6001-00型检波器不同脉冲宽度条件下与连续波时的灵敏度基本一致。WB-CD01型检波器的检波波形前沿出现过脉冲，而2087-6001-00型检波器无此现象。     

相干场成像探测器噪声定量化占比模型

为解决激光相干场成像系统探测器噪声相对总噪声的定量化占比估计问题,分析探测器噪声是否为主要噪声源,提出一种探测器噪声占比权重定量化分析计算方法.基于光电子统计方法得到系统信噪比方程,并引入信噪比中间参数估计方程,建立了探测器噪声相对总噪声的占比权重定量化计算模型.结合理论分析与实验测量进行验证,结果表明:针对构建的相干场成像实验系统,探测器噪声占比权重达52%,进一步分析可知实验在大气相对宁静的夜晚进行,系统受背景光噪声和湍流噪声影响小,探测器噪声是主要噪声源.所提方法可有效估算探测器噪声占比权重,具有便捷、高效的特点,可用于实际相干场成像系统探测器噪声定量化评估测量分析.     

Spontaneous excitation of a detector in circular motion coupled to massless Rarita–Schwinger fields in vacuum

We study the spontaneous excitation of a detector (modeled by a two-level atom) in circular motion coupled nonlinearly to vacuum massless Rarita–Schwinger fields in the ultrarelativistic limit and demonstrate that the spontaneous excitation occurs for ground-state atoms in circular motion in vacuum but the excitation rate is not of a pure thermal form as that of the atoms in linear uniform acceleration. An interesting feature is that terms of odd powers in acceleration appear in the excitation rate whereas in the linear acceleration case there are only terms of even powers present. On the other hand, what makes the present case unique in comparison to the atom’s coupling to other fields that are previously studied is the appearance of the terms proportional to the seventh and ninth powers of acceleration in the mean rate of change of atomic energy which are absent in the scalar, electromagnetic and Dirac field cases.     

Design and implementation of the detector control system for the BESⅢ drift chamber cosmic ray test

After the construction of the BESⅢ drift chamber, a long period of cosmic rays test is necessary to verify its performance. This also provides a good opportunity to integrate the detector readout electronics and Detector Control System (DCS) into a unified working system. The goal of the DCS is to guarantee reliable physics data quality and the safe operation of the detector. It monitors and controls the HV, gas, VME crates and the nvironmental variables. The upper-level system is mainly developed from LabVIEW and the lower-level system mainly uses MCU and PLC technology. The system is designed to be highly flexible and scalable so that it can be applied to other detectors with little or no change. In the immediate future, it will be integrated into the entire BESⅢ Slow Control System.     

4H-SiC肖特基二极管γ射线探测器的模型与分析

 在研究反偏压4H-SiC肖特基二极管作为g射线探测器工作机理的基础上建立了数值模型,模拟了不同偏压和辐照剂量率下探测器的暗电流、工作电流和灵敏度。模拟结果表明:探测器的灵敏度随反向偏压的增加而上升;对于Au/SiC肖特基二极管,有源区掺杂数密度为2.2×10¹⁵ cm^-3时,0 V偏压下探测器的灵敏度为13.9×10^-9 C/Gy,100 V偏压下为24.5×10^-9 C/Gy。计算结果与实验数据符合得较好。     

高效毛细管电泳的光学检测

引用４９篇近几年来国内外的有关文献,介绍了除紫外可见检测法外的其它几种光学检测法在高效毛细管电泳中的应用和发展概况。     

基于FPGA 的超导动态电感探测器频梳读出信号产生

超导动态电感探测器(Kinetic Inductance Detectors, KIDs) 作为一种新型的超导探测器, 在天文学等领域得到了广泛应用, 具有高灵敏度、 高能量分辨率等优点, 并且可以通过频域复用直接扩展到大型阵列. 然而, 为了支持上千像素的探测,KIDs 阵列需要产生复杂的频梳信号, 占用较大的信号带宽. 因此, 数模转换器件(Digital-to Analog Converter, DAC) 的采样率对于 KIDs 阵列的读出电路实现至关重要. 基于JESD204B 传输协议的高速 DAC相较于传统低电压差分信号(Low-Voltage Differential Signaling, LVDS) 协议的转换器具有更高的采样率和传输速率, 可用于频梳信号波形的产生. 为此, 本文提出了一种基于现场可编程门阵列(Field Programmable Gate Array, FPGA) 的设计, 以 Xilinx 公司 Kintex-7 系列 FPGA 为主控芯片, 通过高速串行接口JESD204B 和高速 DAC 芯片AD9136 实现高速数据传输,DAC 采样率为2 GSPS, 能生成带宽为1 GHz 的基带信号. 实验结果表明, 该设计能够有效地生成复杂的频梳信号, 具有较高的信号质量和灵活性, 解决了传统 DAC 及直接数字频率合成(Direct Digital Synthesizer, DDS) 器件难以产生复杂多变波形的难题, 有助于拓展 KIDs 阵列的工程应用.