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Simulation research on time resolution based on Cherenkov radiation

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Radiation Detection Technology and Methods 2021年第3期5卷 421-429页

作者： Xiaorou Han Long Wei Xianchao Huang Haohui Tang Yingjie Wang Wen He daowu li Zhiming Zhang Beijing Engineering Research Center of Radiographic Techniques and Equipment Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Jinan Laboratory of Applied Nuclear Science Jinan 250131China

Purpose A faster time performance can be achieved by focusing on prompt emitted photons,such as Cherenkov *** this study,the time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators were first simulated,and we evaluated the detector performance and discussed ways to improve the coincidence time resolution(CTR)results for the detector with the three ***,we compared detection efficiency of Cherenkov radiation in three *** In this work,we recorded the step-by-step information of Cherenkov photons and the electrons that produced them in the radiator,information of photons on the photon outputting surface,and the step-by-step information tracing of the par-ent charged particles(electrons)to evaluate the factors influencing the performance time of the detector based on ***,we usually use a photon amplitude timing in the experimental implements,and the arrival time of an event is defined as the arrival time of the first photon of the event *** The time fluctuations of Cherenkov photons transmission in the three Cherenkov radiators with a 5 mm length were simulated as 28.5 ps for PbF,40.1 ps for PbWO_(4),and 24.7 ps for Al_(2)O_(3).After considering other factors such as quantum efficiency(QE)of 30%and transit time spread(TTS)of 10 ps from the process of practical electronics,the CTR of a pair of single-pixel detectors were 56.6 ps for PbF_(2),78.8 ps for PbWO_(4),and 46.3 ps for Al_(2)O_(3) with a thickness of 5 *** detection efficiency of PbF_(2) is 32.25%,PbWO_(4) of 31.91%and Al_(2)O_(3) of 8.14%in the case of 5 mm *** The simulation results indicated that using the Cherenkov photons produced in PbF_(2),PbWO_(4),Al_(2)O_(3) for detec-tor timing can obtain good CTR *** this study,it demonstrates that it is possible to achieve a pretty good CTR with an improved QE and a reduced TTS of the photodetector.

关键词： Cherenkov radiation Coincidence time resolution PbF_(2) PbWO_(4) Al_(2)O_(3)

Image reconstruction for the coded aperture system in nuclear safety and security using a Monte Carlo-based system matrix

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Radiation Detection Technology and Methods 2023年第2期7卷 263-270页

作者： Yue Yu Xiaoli Sun Zhiming Zhang Shuangquan liu Xiuzuo liang daowu li Lei Shuai Tingting Hu Long Wei Beijing Engineering Research Center of Radiographic Techniques and Equipment Institute of High Energy PhysicsChinese Academy of SciencesBeijing100049China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing100049China Jinan Laboratory of Applied Nuclear Science Jinan250131China

Purpose Accurate localization of radioactive materials is critical to nuclear safety and nuclear security.A coded aperture imaging system provides a visualization ***,the correlation method has poor reconstruction performance for sources with low counts and for extended *** In this study,a Monte Carlo optimization-based MLEM algorithm(MC-MLEM)is *** system matrix was obtained by accurate Monte Carlo simulation,so the physical effects such as mask penetration that affect the imaging process were taken into account in the MLEM *** the simulation process,the normalization of the system matrix was realized by controlling the source at different position of the source plane to have the same activity and emission *** The experimental results showed that compared with the correlation method,the MC-MLEM algorithm could improve the signal-to-noise ratio and angular resolution and locate the source position quickly and accurately under low count ***,the MC-MLEM algorithm could reconstruct the shape of the extended source and the expected activity ratio of cold-hot sources with large activity *** The MC-MLEM algorithm improved the imaging results and enhanced the reconstruction performance.

关键词： Coded aperture System matrix Image reconstruction Low count imaging Extended sources

Design of a high-sampling-rate electronic module for array-detector positron annihilation lifetime measurements

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Radiation Detection Technology and Methods 2019年第3期3卷 127-135页

作者： Jiale Cai daowu li Yingjie Wang Zhiming Zhang Peilin Wang Haohui Tang Baoyi Wang Xingzhong Cao Fuyan liu Long Wei Beijing Engineering Research Center of Radiographic Techniques and Equipment Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China

Introduction In this study,a high-time-resolution electronic module with a high channel density and low power consumption was designed for the measurement of the multi-detector array positron annihilation *** electronic module consisted of 32 input channels,and each channel provided a high sampling rate up to 5.12 GSPS based on a Domino Ring Sampler 4(DRS4)*** to the high-speed flash analog-digital converter(FADC),DRS4 chip has a higher channel density with an affordable lower price and power *** The developed electronic module was also capable of real-time data analysis for directly extracting the time information of input signals at the data acquisition site,thereby significantly decreasing the data *** digital constant fraction discriminator(DCFD)algorithm was implemented in the field programmable gate array(FPGA)for performing the time *** The coincidence time resolution of the electronic module was measured,and the test results revealed a value of 26 ps.A prototypical 16-pixel detector module of the multi-detector system was evaluated using this electronic module,and the coincidence time resolution of the prototypical module was 411.84 *** The electronic module was confirmed to satisfy the severe requirements of the multi-array-detector positron annihilation lifetime measurement *** was also suitable for other high-time-resolution,high-channel-density,costeffective,and low-power-consumption applications.

关键词： Digital constant fraction discriminator FPGA DRS4 Positron lifetime

An efficient method and system for simultaneously measuring the performance of vast scintillating materials

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Nuclear Science and Techniques 2012年第3期23卷 144-149页

作者： CHEN Yan ZHANG Zhiming li daowu SHUAI Lei HUANG Xianchao TANG Haohui li Ting ZHUANG Kai WANG yingjie liU Yantao ZHANG Yiwen CHAI Pei liU Shuangquan ZHU Meiling WANG Baoyi WEI Long Laboratory of Nuclear Analysis Techniques Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Beijing Engineering Research Center of Radiographic Techniquesand Equipment Beijing 100049 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

A method and system for automatically and simultaneously measuring the light output of multiple scintillators,or each scintillating unit of an array,were *** a large area flat panel PSPMT H8500,the light output and energy resolution were obtained automatically by comparing with reference scintillators or array using an Energy Table,Look-up Table and energy spectrum *** aim of developing an efficient performance evaluation of scintillators was *** the method,a scintillator performance testing system was set up and six LYSO crystals and a 3×3 LYSO array were *** results showed that the light output and energy resolution were accurately measured *** deviation of repeat measurements for the same sample was not more than 2%,and the nonlinear deviation of the system was not more than 3%.The system is suitable for measuring the performance of crystals,especially where the mass measurement of crystals and arrays is required.

关键词：性能测试系统同时测量闪烁材料能量分辨率线性偏差光输出绩效评估重复测量

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Compact MPPC-based coded aperture imaging camera for dual-particle detection

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Radiation Detection Technology and Methods 2021年第1期5卷 61-70页

作者： Jing Guo Xiaoyu Pang Jiale Cai daowu li Xiaoming Wang Xuanhou Hu Yue Yu Shuangquan liu Xiuzuo liang Yiwen Zhang Lei Shuai Long Wei Beijing Engineering Research Center of Radiographic Techniques and Equipment Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Jinan Laboratory of Applied Nuclear Science Jinan 250131China

Purpose Fast neutrons and gamma-ray imaging detection is an effective way to detect and identify radioactive material in the field of nuclear security.A compact coded aperture imaging(CAI)camera was designed to be sensitive to both gamma and neutron radiation based on plastic scintillators and multi-pixel photon counters(MPPC).Methods MPPCs coupling with the 13×13 pixelated plastic scintillators one-to-one were utilized to reduce the scale of the CAI system while maintaining good positional *** symmetric charge division(SCD)circuit was adopted to reduce the 169 signals output from the MPPC array to *** waveform was collected and processed with four Domino Ring Sampler 4(DRS4)chips and two 16-channel analog-to-digital converter(ADC)*** the pulse shapes of fast neutrons would be broadened after elastic scattering multiple times in the scintillators,the Anger-Logic method was applied to eliminate multiple elastic scattering events so that good pulse shape discrimination(PSD)performance can be *** The imaging and detection ability of the camerawas evaluated using the 241Am-Be(5.9×10^(5) n/s)neutron source and 137Cs(370 MBq)*** camera can be used to detect fast neutrons(0.5–10 MeV)and gammarays(0.2–2.5MeV).Furthermore,it can implement efficient neutron/gamma PSD capabilities in the mixed-field *** figure of merit(FOM)of the camera calculated at 400keVee energy cut is *** A compact MPPC-based CAI camera was designed to detect and discriminate fast neutrons and gamma *** good PSD performance was well suited to distinguish fast neutrons from gamma rays in a dual-particle *** portable design makes it promising for complex monitoring scenarios in nuclear security.

关键词： Coded aperture imaging Fast neutron imaging Gamma imaging n-γdiscrimination

Design of readout electronics based on peak-holding circuit and multiplexer for a fast neutron spectrometer

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Radiation Detection Technology and Methods 2018年第1期2卷 38-48页

作者： liyang Sun Kai Zhuang Xiaoming Wang Fanjian Zeng Heng An daowu li Yuxiong Xue Zhiming Zhang Wei Zhou Yingjie Wang Baotong Feng Peilin Wang Xiaohui li Jiale Cai Teng Tong Fanhui Meng Junguang Zhou Huan Huang Xuanhou Hu Xiubo Qin Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Beijing Engineering Research Center of Radiographic Techniques and Equipment Beijing 100049China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Lanzhou Institute of Physics Chinese Academy of Space TechnologyLanzhou 730000GansuChina

Background Fast neutron detection is meaningful in many research fields such as space environment monitoring.A scintillating fiber array model for fast neutron detection was proposed and developed in *** applications of the model require electronics in small *** To design a dedicated electronic system to readout and process the 384-channel signals from scintillating fiber array,and to use the designed system to fabricate a neutron detector for aerospace *** With the method of nuclear recoil,fast neutron is detected by tracking recoil proton of n–p scatter in scintillating plastic *** the peak-holding circuits and multiplexers,the system size and power consumption were *** The detector fabricated with the designed system,had 34 cm×34 cm×27 cm mechanical size,20.4 kg weight,and 30.05W power *** to traditional waveform sampling electronics,the designed electronics was highly integrated and had a small *** readout electronics also gave a better energy resolution of 39%in neutron detection,while the energy resolution was 43%in previous *** In this study,a highly integrated readout electronic system was designed and *** detector using the system gave good *** designed electronics had potential development in fast neutron detection and other high energy physics detection system.

关键词： Multiplexer Peak-holding circuit Readout electronics Fast neutron detection

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海南自贸港城市社区治理的困境及创新路径

海南热带海洋学院学报 2023年第6期30卷 118-127页

作者：吴方彦黎道武海南大学公共管理学院海口570228 海南省业主委员会协会海口570205

海南城市社区存在的治理困境主要有:小区业主与物业公司矛盾较为突出,成立业委会的小区比例较小,“候鸟小区”治理难度较大,老旧小区和“三无小区”更新缓慢,涉小区治理事项审批程序繁杂。城市社区治理困境的主要原因:治理主体错位;职... 详细信息

海南城市社区存在的治理困境主要有:小区业主与物业公司矛盾较为突出,成立业委会的小区比例较小,“候鸟小区”治理难度较大,老旧小区和“三无小区”更新缓慢,涉小区治理事项审批程序繁杂。城市社区治理困境的主要原因:治理主体错位;职能部门缺位;制度建设缺失;自治实践缺少;统筹力量缺漏。海南自贸港应当持续推进城市社区治理领域的制度集成创新,构建具有海南地域特色的党建引领下的社区治理共同体,为海南自贸港的高质量发展奠定坚实的社区治理基础。

关键词：海南自贸港城市社区社区治理共同体治理创新

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基于透镜阵列多元聚焦的连续晶体三维位置灵敏探测器设计和仿真

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原子能科学技术 2024年第1期58卷 239-247页

作者：李婷庄凯李道武梁秀佐刘彦韬张译文孔令钦章志明帅磊魏龙中国科学院高能物理研究所北京市射线成像技术与装备工程技术研究中心北京100049 中国科学院大学核科学与技术学院北京100049 国家原子能机构核技术(核探测与核成像)研发中心北京100049 济南中科核技术研究院山东济南250131

连续晶体闪烁体探测器可以实现γ射线作用点的三维位置定位。本文提出一种新的探测器结构,引入透镜阵列实现作用点定位。探测器采集多元聚焦图像,从而改变对连续晶体闪烁光分布探测的需求。文中建立连续晶体、透镜阵列和光子计数器阵列... 详细信息

连续晶体闪烁体探测器可以实现γ射线作用点的三维位置定位。本文提出一种新的探测器结构,引入透镜阵列实现作用点定位。探测器采集多元聚焦图像,从而改变对连续晶体闪烁光分布探测的需求。文中建立连续晶体、透镜阵列和光子计数器阵列的模型进行模拟研究,建立多元聚焦的光路反演重建算法定位γ射线作用点的三维位置。通过重建结果分析评估基于透镜阵列的连续晶体探测器性能,这种结构具有较好的定位能力和位置分辨。对于尺寸为48 mm×48 mm×45 mm的硅酸钇镥(LYSO)闪烁晶体,实现了xy平面位置分辨优于1.54 mm,z方向位置分辨优于3.13 mm。基于连续晶体和透镜阵列结构的探测器还可对多作用点的情形进行重建,分析三组选定位置的重建结果,该结构对双作用点定位具有可行性。

关键词：连续晶体探测器透镜阵列作用点定位位置灵敏探测器

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符合多普勒展宽测量系统的性能研究

核技术 2008年第8期31卷 577-582页

作者：王丹妮王宝义张兰芝钟玉荣章志明李道武魏龙张天保中国科学院高能物理研究所核分析技术重点实验室北京100049 中国科学院研究生院北京100049 烟台大学光电信息学院山东264005

研制了一套具有外触发和内触发两种工作模式的高性能符合多普勒展宽测量系统（Coincident Doppler Broadening，CDB），其中外触发模式具有更好的时间分辨（FWHM〈7ns）和更高的峰谷比（〉10^6），适于强源高计数率测量（符合计数率〉20... 详细信息

研制了一套具有外触发和内触发两种工作模式的高性能符合多普勒展宽测量系统（Coincident Doppler Broadening，CDB），其中外触发模式具有更好的时间分辨（FWHM〈7ns）和更高的峰谷比（〉10^6），适于强源高计数率测量（符合计数率〉200／s）；数字化的内触发模式，由于不需要复杂的外围电路，造价便宜、稳定性好因而更为实用，但时间分辨率（94ns）和峰谷比（〉10^5）明显逊于外触发模式。通过软件算法进行滤堆积处理后，在低符合计数率（～100／s）测量时峰谷比也能达到外触发水平（10^6）。本文系统介绍了谱仪的基本性能，测试了高纯金属标样Cu、Ni、W和A1的多普勒展宽谱，同时通过飞行正电子湮没（Positron Annihilation in Flight）实验验证了相对论动能公式E^2tatal=p^2c^2＋m^2ec^4，结果表明谱仪在时间分辨和去本底（峰谷比优于10^6）方面都具有较高的性能；作为应用例，表征了偏离正常化学比NiA1合金正电子湮没位置的化学环境，结果表明，CDB系统对开空间缺陷周围的化学环境变化具有较高的灵敏性，在材料微结构研究领域具有广泛的应用前景。

关键词：正电子湮没符合多普勒展宽性能研究

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