X-ray photon-counting detector based on a micro-channel plate for pulsar navigation

The pulse time of arrival （TOA） is a determining parameter for accurate timing and positioning in X-ray pulsar navigation. The pulse TOA can be calculated by comparing the measured arrival time with the predicted arrival time of the X-ray pulse for pulsar. In this study, in order to research the measurement of pulse arrival time, an experimental system is set up. The experimental system comprises a simulator of the X-ray pulsar, an X-ray detector, a time-measurement system, and a data-processing system. An X-ray detector base is proposed on the basis of the micro-channel plate （MCP）, which is sensitive to soft X-ray in the 1–10 keV band. The MCP-based detector, the structure and principle of the experimental system, and results of the pulse profile are described in detail. In addition, a discussion of the effects of different X-ray pulse periods and the quantum efficiency of the detector on pulse-profile signal-to-noise ratio （SNR） is presented. Experimental results reveal that the SNR of the measured pulse profile becomes enhanced as the quantum efficiency of the detector increases. The SNR of the pulse profile is higher when the period of the pulse is smaller at the same integral.

Development of an ultrafast detector and demonstration of its oscillographic application

A dilation X-ray detector(DIXD)based on time dilation and microchannel plate(MCP)gated technology has been reported.The DIXD passes a driving pulse along the transmission photocathode(PC)to obtain a dilated electron signal and finally achieves a high time resolution of 12 ps.Furthermore,the waveform of the PC driving pulse can be obtained using the DIXD,and a DIXD oscillographic function can be obtained.An experiment is presented to demonstrate the DIXD oscilloscope.The waveform of the PC driving pulse from points t_(1) to t_(12) is achieved by the DIXD.The waveform agrees well with that measured by a high-speed oscilloscope with a difference of less than 6%.The maximum theoretical bandwidth of the DIXD oscilloscope is theoretically studied.The bandwidth is limited by the potential difference between the PC and mesh.When the potential difference is 3.4 kV,the theoretical limiting bandwidth is 1000 GHz.The bandwidth increases with an increase in the potential difference.

Electrostatic-lenses position-sensitive TOF MCP detector for beam diagnostics and new scheme for mass measurements at HIAF

A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China.Characterized by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory reconstruction.Moreover,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis.Most importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.

Detection efficiency evaluation for a large area neutron sensitive microchannel plate detector

In this paper, the detection efficiency of a large area neutron sensitive microchannel plate detector has been evaluated. A ^6LiF/ZnS scintillator detector 65 mm in diameter and 0.32 mm in thickness, with product code,EJ426HD2, produced by Eljen Technology, was employed as the benchmark detector. The TOF spectra of these two detectors were simultaneously measured and the energy spectra were then deduced to calculate the detection efficiency curve of the ^nMCP detector. Tests show the detection efficiency@25.3 me V thermal neutrons is 34% for this ^nMCP detector.

Advances in nuclear detection and readout techniques

“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.

Performance optimization of the neutron-sensitive image intensifier used in neutron imaging

As a non-destructive testing technology,neutron imaging plays an important role in various fields,including material science,nuclear engineering,and fundamental science.An imaging detector with a neutron-sensitive image intensifier has been developed and demonstrated to achieve good spatial resolution and timing resolution.However,the influence of the working voltage on the performance of the neutron-sensitive imaging intensifier has not been studied.To optimize the performance of the neutron-sensitive image intensifier at different voltages,experiments have been performed at the China Spallation Neutron Source(CSNS)neutron beamline.The change in the light yield and imaging quality with different voltages has been acquired.It is shown that the image quality benefits from the high gain of the microchannel plate(MCP)and the high accelerating electric field between the MCP and the screen.Increasing the accelerating electric field is more effective than increasing the gain of MCPs for the improvement of the imaging quality.Increasing the total gain of the MCP stack can be realized more effectively by improving the gain of the standard MCP than that of the n MCP.These results offer a development direction for image intensifiers in the future.

Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensional Vernier anode are introduced in detail. A photon counting imaging system was built based on a Vernier anode. The image of very weak optical radiation can be reconstructed by image processing in a period of integration time. The resolution is superior to 100 μm according to the resolution test. The detector may realize the imaging of very weak particle flow of highenergy photons, electrons and ions, so it can be used for high-energy physics, deep space exploration, spectral measurement and bio-luminescence detection.

延迟线阳极光子计数成像探测器研究

基于微通道板的单光子探测器具有体积小、结构紧凑等优点,将其与位置灵敏阳极相结合能够准确记录光子到达的时间信息及位置信息。通过分析延迟线阳极探测器的原理,提出一种基于印刷电路板制备的新型二维交叉延迟线阳极。与传统的电荷直接收集方式不同,该阳极基于电荷感应技术,由高阻感应层代替阳极收集电子,消除了阳极电子再分配带来的噪声。搭建了一套基于交叉延迟线阳极的实验系统并对研制的位敏阳极探测器进行测试,测试结果表明探测器空间分辨率最优为107 um,暗计数为0.23 counts/(cm^(2)·s)。研制的新型交叉延迟线阳极为大面阵单光子成像探测应用奠定了基础。

针对铝板带涂油现状及漏涂问题的研究

涂油机由高压发生器、高压包、刀梁、接地增宽板、计量泵、流量计、在线油膜检测仪等元器件及设备组成。通过改变涂油机的电场,从而改变带电油离子在电场中的活动轨迹及活跃情况来优化涂油机的涂油效果,并通过在线油膜检测仪来实时检测涂油情况及涂油均匀性,最终以在线油膜检测仪检测的结果来反馈涂油机实际涂油效果是否达到控制要求。

YB65包装机防挤烟装置的设计

YB65条盒包装机生产过程中经常出现烟包挤皱、变形、推烟板损坏等现象,进而造成小盒烟包外形不方正等质量问题。经分析发现该现象是由于小盒烟包包装材料及温度设置和设备状况等多种因素共同作用而造成。如果烟包挤皱严重还会造成条烟推板或相关零部件损坏,影响生产。当出现较轻微的烟包挤皱、变形情况时,若工作机构不能有效检测到,从而使产品进入下一道工序,会影响产品质量。文中设计了一种防挤烟装置,YB65条盒包装机安装了该防挤烟装置后,能够检测并剔除小盒烟包挤皱变形的条烟,从而确保了产品质量,有效节约了维修时间和零配件费用。

基于OpenCV和LSD的车牌识别系统研究

传统车牌识别系统存在图像清晰度不够、识别时间长等问题,有时无法成功识别车牌。为解决这一问题,文章采用OpenCV开放源代码计算机视觉库和线段检测器(Line Segment Detector,LSD)设计了一套新型车牌识别系统。首先,对图像进行灰度化预处理,并使用LSD算法快速检测图像中的直线。其次,采用轮廓跟踪方法识别车牌轮廓,并使用基于垂直投影的分割方法来分割车牌字符。最后,采用基于模板匹配的方法识别车牌号码。经过验证,该系统在处理车牌图片模糊和光线较暗的情况下依然能够高效处理,并且能够保持较高的成功率。

X射线脉冲星导航探测器性能研究

为研究用于X射线脉冲星导航的探测系统性能,推导了在光子计数模式下探测系统的信噪比和最小可探测功率的关系表达式,并搭建测量信噪比和最小可探测功率的实验装置.测量了系统的最小可探测功率以及在不同光功率、不同累积时间和不同阈值电压条件下探测系统的信噪比.通过对X射线光子到达时间的测量,构造了X射线脉冲累积轮廓.实验表明:随着光功率和累积时间的增加,累积脉冲轮廓的信噪比提高,累积脉冲轮廓趋于光滑;当阈值电压为-150mV时,信噪比为26.3,累积脉冲轮廓最优;系统的最小可探测功率为3.5×10-16W.

楔条形阳极探测器的性能测试与分析

对研制出的楔条形阳极探测器进行了性能分析与实验测试,分析了引起成像畸变的三个重要因素:到达阳极的电子云半径大小、阳极的电容耦合效应和电子读出电路的性能.电子云半径的过大或过小会相应引起成像的"S"畸变或调制畸变,电容耦合效应和电路噪音也均会引起成像的畸变.此外,测试了探测器的暗计数率、线性度以及空间分辨率等性能,同时分析了微通道板在光照情况下的增益特性和暗计数的一般特性及其产生原因.测试结果表明探测器的成像畸变很小、线性关系较好,空间分辨率优于150μm,微通道板的暗计数率低于0.4count/s*cm2.

基于Vernier阳极微通道板光子计数探测器分割噪声

为消除微通道板光子计数探测器系统中电子噪声的干扰,研究了探测器分割噪声的来源,并提出利用COMSOL软件仿真计算分割噪声的方法.利用有限元方法对基于Vernier阳极探测器的成像过程进行三维建模,实现了一组5×5针孔阵列的模拟成像,计算出Vernier阳极分割噪声所产生的电子云质心位置的偏移量,验证了Vernier阳极探测器成像编码的正确性与仿真研究分割噪声的可行性.通过分析不同参量的阳极面板,利用数值拟合方法,得到电子云质心偏移量与阳极面板设计参量之间的关系.在固定面板参量的前提下,可以通过提高微通道板增益来有效降低分割噪声对质心位置偏移影响.

微通道板增益对光子计数探测器成像性能影响

微通道板作为二维位置灵敏阳极光子计数探测器中的电子倍增器件,其增益特性直接影响探测器的成像性能。搭建了系统测试平台,测量了微通道板的增益随电压变化曲线,并获得了3块微通道板叠加后的脉冲高度分布曲线。根据测试结果以及脉冲高度分布曲线的能量分辨率与探测器增益的均匀性之间的物理关系,选择合适电压值和增益对探测器的性能进行优化,探测器分辨率由3.56lp/mm提高到4.49lp/mm,获得了清晰图像,为探测器的研制提供了技术支持。

使用感应电荷位敏阳极的极紫外单光子计数成像系统

研制了用于月基极紫外成像相机的二维极紫外位敏阳极光子计数成像探测器原型样机,该探测器系统主要由工作在脉冲计数模式下的微通道板堆、楔条形感应位敏阳极及相关的模拟和数据处理电路组成。设计和制备了周期为1.5mm,有效直径为47 mm的三电极楔条形位敏阳极,研制了最高计数率为200 kHz的前端模拟和数字电路。测量了探测器的暗计数率、脉冲高度分布、增益、线性及空间分辨率等工作特性。测量结果表明,探测器的空间分辨率为7.13 lp/mm(即0.14 mm),满足月基极紫外相机对空间分辨率的要求。

多功能墙体探测仪的设计方法

针对墙体中水管、电线、金属物体的探测问题,设计了3种无源传感器,并设计了相关数据处理方法以确定被测物体的中心位置。利用PCB覆铜,制作了用于探测水管的电容极板以及用于探测电线的金属天线。建立了水管检测模型,得到输出信号随被测物体位置的变化规律。基于差分探头模型,提出了一种利用PCB线圈作为敏感单元的金属探测方法,通过数值计算,保证了差分线圈的平衡。最后,针对上述传感单元,设计了被测物体的中心检测算法。测试数据表明,各传感单元均具有较大的探测深度,中心检测误差均在合理范围之内。

极紫外波段微通道板光子计数探测器

研究了一种极紫外波段微通道板(MCP)光子计数探测器,用于探测地球等离子体层中极微弱的30.4 nm辐射。通过改变电压、温度等参数对比了该微通道板光子计数探测器的暗噪声和分辨率的变化。结果表明:微通道板探测器的暗噪声主要来源于残余气体离子反馈和热噪声,因此要降低探测器暗噪声,应对微通道进行彻底的预处理除气,并尽量避免探测器在高温状态下工作,常温下经过预处理的微通道板光子探测系统的暗计数率仅为0.34 count/(s.cm2)。系统的分辨率主要受电压和计数率的影响,受温度影响不明显。由于不同的微通道板有不同的耐压范围,过小或过大的电压或计数率都会造成系统分辨率的降低。

一维电阻阳极位置灵敏探测器的研制

叙述了一维电阻阳极位置灵敏探测器的原理、构成以及相应的电子学获取系统，测量了探测器的各种特性和参数。

用于超灵敏小型迴旋加速器质谱计的微通道板粒子探测器

我们制造并测试了为超灵敏小型通旋加速器质谱计研究设计的单粒子探测系统。探测器由Al_2O_3打拿极、微通道板电子倍增器和阳极三部分组成。入射离子沿80°角方向轰击打拿极,以0.8电子/keV的转换系数产生数目与离子能量成正比的次级电子,每个电子在不同的通道管内单独放大至饱和,阳极收集的电荷数与入射离子能量成正比。用选择甄别阈的方法可以有效地将离子计数与本底分开。从实测数据外推到40keV K或Ar离子时可知:相应于90％计数效率的本底率为10^(-3)/S。探测系统的能量分辨△E=6.5keV,可以用于测量极低能量的重离子谱。