高计数率下的四路反堆积放大电路

介绍一种在高计数率情况下的反堆积放大器,它允许通过的平均计数为105/s.该放大器为了适应高计数率的要求,设计了基线调节功能和反堆积功能,给出了堆积标志,以便后继电路的处理.该电路在一个单宽NIM插件中有完全相同的四路电路工作,结构紧凑,体积小,工作性能稳定.     

大面积GEM中子探测器高计数率读出电子学系统研制

研制并测试了GEM中子探测器的512通道高计数读出电子学系统,以满足中国散裂中子源高效率、高分辨、高通量二维位置灵敏中子探测器的需求。系统以Kintex-7 FPGA作为系统控制和数据分析的核心,使用8块AS20Board前端芯片对灵敏面积为200 mm×200 mm的探测器的两个维度的信号进行读出,读出通道为256×256。读出数据经FPGA分析后通过千兆以太网传输至计算机显示。计算机可通过千兆以太网发送配置指令对前端采样电路和FPGA算法进行配置。系统与探测器组装后在中子束流实验中测得系统最高瞬时计数率为（1.2±0.1）×106 s^-1,系统运行稳定,受噪声干扰小。     

1220 Quantulus液闪谱仪测量3H计数效率的刻度

介绍了1220Quantulus液闪谱仪测量^3H计数效率的刻度方法。实际结果表明，用商用猝灭校正源来刻度仪器计数效率，首先应检验对实验被测样品的适用性，否则会使样品测量值有较大误差；对于一般的^3H常规监测，样品制备程序相同，猝灭情况变化不大，猝灭系数SQP（E）在711－732之间波动，因而可以用被测样品的空白材料无氚水作为猝灭剂来配制猝灭系列源，并用它制作的校正曲线来刻度仪器计数效率，或者简单地用与被测样品猝灭情况相近的源作为标准来确定计数效率。     

采用联反符合计数系统的康普顿抑制γ谱仪

本文介绍的用于低本底γ测量的小型康普顿抑制谱仪采用并联取样反符合计数系统，同时具有简单有效的物质屏蔽和数据自动采集和分析功能，在阱型反符合屏蔽条件下，谱仪对置于ＮａＩ（Ｔｌ）主探测器上方３．５ｃｍ处的＾１３７Ｃｓ薄膜源的探测灵敏度为７４．３７Ｐａ；在５０－２０００ＫｅＶ能区的积分本底为１５ｍｉｎ＾－１，与无反符合屏蔽时相比降低了６１．５％。     

核电厂堆外中子测量系统闪发高计数率问题研究

从故障现象、原因排查和解决措施三个方面,分析了我国核电厂近期发生的堆外中子测量系统闪发高计数率异常中所涉及的电缆接头问题和探头故障问题,提出了核电厂应关注堆外中子测量系统设备制造和安装的质量等建议,为解决和避免类似的堆外中子测量系统闪发高计数率问题提供借鉴。     

High Speed HPD for Photon Counting

We have succeeded in the development of a high-speed Hybrid Photodetector (HPD), by using a reduced electron lens and a newly developed avalanche diode (AD) with very low capacitance. The HPD shows fast time response of less than 500 ps in both rise and fall times, and good timing resolution of 26 ps (one sigma) for single photons at full illumination on a photocathode 8 mm in diameter. Limiting factors of the timing resolution were further investigated, and were found to be the transit time difference of electrons in vacuum along the photocathode and the jitter of the electronics. The timing resolution is 15 ps for illumination of less than 5 mm on the central part of the photocathode, which includes the jitter of 13 ps from the electronics. This resolution is the world's highest for HPDs, and matches the resolution of MCP-PMTs. Both a GaAsP photocathode having close to 50% quantum efficiency in the visible and a bialkali photocathode having 34% QE in the UV were fabricated in view of making this device available for various applications. In this paper, we report the results of our evaluation, including discussion about the limiting factors of the timing resolution for the new HPD.     

A Linear Amplifier Suitable for High Counting Rates

A linear amplifier suitable for high counting rates is described. The amplifier uses double-delay-line shaping to minimize base line shifts and to enable timing signals to be obtained from the zero crossover. Miniature delay lines are used and the amplifier is designed to work with lines as short as 100 nanoseconds. It has a maximum gain of 500 and a rise time of 18 nanoseconds. To minimize delay line reflections, the lines are terminated at both ends. A novel circuit is used to obtain the delay line shaping. The amplifier has good overload characteristics and is constructed very compactly. It plugs into a frame designed to accomodate a series of compatible circuits of modular design. The front panel space required is 3.6 by 7 inches. Circuitry and performance are described.     

HI－13串列加速器升级工程在线同位素分离器高质量分辨谱仪物理设计

HI－13串列加速器升级工程中的在线同位素分离器(ISOL)高质量分辨谱仪要求20000的质量分辨率。本工作采用大小铁双能量结构削弱能量色散，有效解决了束流能散过大导致的谱仪质量分辨率低的问题。结果表明：当束流高斯分布宽度为0.06mm和10mrad时，谱仪的质量分辨率达到了33400；若考虑加速段引入的0.002%能散，谱仪最终的质量分辨率为20000。     

闪烁室探测器计数率随温度变化补偿特性研究

由于环境温度变化会使ZnS(Ag)闪烁探测器的计数率出现明显的波动现象,使测量结果出现偏差,基于单片机和补偿电路,通过选取合适的探测器和光电倍增管作为实验材料,分别将光电倍增管的高压和阈值与温度相结合,通过最小二乘法对实验数据进行拟合分析计算,对探测器计数率进行温度补偿,从而最大限度改善探测器的温度特性,提高测量的准确性和稳定性。通过测试验证,探测器温度补偿效果良好。     

System Requirements for High-Resolution Gamma-Ray Spectrometry at High Counting Rates

The full potential of high-resolution gamma-ray spectrometers has been severely hampered by degradation in the quality of the pulse-height spectrum at high input data rates. Over the past year or two considerable effort has been expended in the examination of this problem. This paper will briefly review the nature of these instrumental difficulties, define realistic experimental requirements, and illustrate state-of-the-art solutions to these problems. A DC-coupled system which has been developed in our laboratory for high-rate applications will be described and performance presented.     

用于瞬发γ中子活化在线元素分析的高计数率γ谱仪

高纯锗探测器制技术及谱仪电子学的迅速发展，使瞬发γ中子活化分析所要求的高计数率γ谱仪已可以由适当地选择谱仪系统中的各个部件而实现，本文针对ＰＧＮＡＡ的应用，就高计数率γ谱仪对各训件指标的要求与选择依据及系统总体考虑进行介绍，并给出系统所能达到的总性能参数。     

质谱法测定西安脉冲反应堆~(99)Tc嬗变率

热堆是嬗变长寿命放射性裂变产物的有效途径之一。西安脉冲反应堆属于低中子通量热堆(满功率运行时热中子通量密度为4.5×10~(13)cm~(-2)·s~(-1)),利用该堆开展了6个裂变产物~(99)Tc靶的嬗变技术研究。经过6h满功率辐照,~(99)Tc辐照产物~(100)Ru在靶件中的含量接近10~(-6)水平,为测定~(99)Tc的嬗变率,采用高灵敏的质谱分析方法准确测量辐照产生的痕量~(100)Ru的量。为克服本底干扰和同质异位素的影响,采用单接收ICP—MS测量了未辐照前锝金属靶件中的杂质含量,采用~(99)Ru同位素稀释多接收电感耦合等离子体质谱技术测定了化学制样流程本底铷的含量,并对流程本底中Ru同位素比值进行了分析,最后采用同位素稀释质谱技术测量了6个辐照靶件~(100)Ru的含量。结果表明,嬗变率测量值的扩展不确定度好于1.5%。     

High Efficiency Photon Counting Detectors for the FAUST Spacelab Far Ultraviolet Astronomy Payload

We compare the performance of sealed tube microchannel-plate position sensitive detectors having transmission CsI photocathodes or opaque CsI photocathodes. These devices were developed for the FAUST Spacelab payload to accomplish imaging surveys in the band between 1300? and 1800?. We demonstrate that photocathode quantum efficiencies in excess of 40% at 1216? have been achieved with the transmission and the opaque CsI photocathodes. The effect of the photoelectron trajectory on the spatial resolution is assessed. Spatial resolution of <70?m FWHM has been obtained and is maintained up to event rates of 5×104 sec-1. Background rates of 0.55 events cm-2 sec-1 have been achieved and low distortion (<1%) imaging has been demonstrated.     

Influence of Sample Thickness on Detection Efficiency of High Purity Germanium Gamma Spectrometer

<正>Seven soil samples with different packing thickness and the same batch were prepared and measured by high-purity germanium gamma spectrometer.The relationship between the thickness of soil sample and the detection efficiency was obtained under the premise of considering the influence of sample self-absorption for four different energy nuclides of~(210)Pb (46.5 keV),~(226) Ra(352 keV),~(232) Th (583 keV) and~(40)K (1 460.8 keV).     

Processing of Detector Signals at Very High Counting Rates for Precision Pulse-Height Analysis

Systems with naxiwum pulse flow capacity are discussed. It is shown that the upper limit of the permissible counting rates is set by pile up induced phenomriena, which are analyzed here. The best pulse stretching mode miinimizing pile up is peak value extraction. The basic statistical properties of such a device are investigated. These principles are applied to the design of an electronic system which comprises a fast amplifier, a high speed linear gate and a biased pulse stretcher. The noise properties of the anmplifier were studied using the autocorrelation function mreasured experimrentally. The system allows one to detect a particles with satisfactory pile up performances and negligible spectrum distortion in the presence of back-scattered protons up to 108 counts/sec. Applications to pulsed high energy accelerators are described.     

Test of a High Throughput Detector on the X-ray Crystal Spectrometer of the EAST

An attempt was made to improve the spatio-temporal resolution of the tangen- tial X-ray crystal spectrometer (XCS) on the Experimental Advanced Superconducting Tokamak (EAST) by evaluating experimentally the applicability of a novel X-ray photon detection tech- nology for measuring the satellite spectra of Ar XVII with a high counting rate. High-resolution experimental data on the profiles of ion temperature and plasma rotation velocity facilitate the studies of the mechanisms underlining important physical phenomena, such as plasma heating, L-H transition and momentum transport. Based on silicon diode array and single-photon counting technology, a relatively small area (83.8×33.5 mm 2 ) two-dimensional detector was successfully in- stalled and tested in the recent EAST campaign. X-ray photon counting rate higher than 20 MHz was observed for the first time, and high quality satellite spectra were recorded for ion temperature and plasma rotation measurement, indicating that the new technology is suitable for the next-step high-resolution XCS on EAST, and the deployment of a detector array with a much larger X-ray sensing area is planned for better plasma coverage.     

逐比特可变高码率通用接收机研究

在高码率通用接收机中,为解决码率逐比特可变的问题,提出了变采样的设计方案;同时,还针对通用解调中的几项关键技术开展研究,提出了适用于MPSK及16QAM调制模式的算法结构;最后,针对具体指标进行了软硬件测试,表明该设计方案满足系统要求。     

High Dose Rate Burnout in Silicon Epitaxial Transistors

This paper presents experimental results for ionizing radiation-induced burnout in n-p-n transistors. The results indicate a dose-rate and a collector bias threshold for transistor burnout. The collector voltage threshold was shown to be on the order of 2/3 BVCEO and the dose-rate threshold was shown to be on the order of 2 × 1010 rad(Si)/s. The triggering mechanism was postulated to be caused by high current injection which results in avalanche breakdown fields developing across the n-n+ substrate boundary.     

核计数实时修正器

本文介绍一种具有死时间计数损失实时修正能力的新型双插宽NIM插件——核计数实时修正器的电路原理、实验结果和主要技术指标。     

基于脉冲幅度谱的3He正比计数管中子散射谱仪探测系统关键参数测定方法

中子散射谱仪探测系统各部件性能参数需相互匹配,准确的参数测定方法利于改进谱仪探测系统的实际性能,提高物理实验数据质量（可信度等）。本文基于³He正比计数管中子散射谱仪探测系统,开发了脉冲幅度甄别器甄别阈、核辐射探测器工作电压以及气体核辐射探测器性能参数的脉冲幅度谱测定方法,这些方法较传统的积分曲线测定方法、坪曲线测定方法以及电压-电流曲线测定方法具有测量时间短、准确度高、应用范围广等优势。