LHAASO WCDA前端读出电子学的研究

发布时间：2018-01-18 15:34

本文关键词：LHAASO WCDA前端读出电子学的研究　出处：《中国科学技术大学》2017年博士论文　论文类型：学位论文

【摘要】：大型高海拔空气簇射观测站(Large High Altitude Air Shower Observatory,缩写为LHAASO)是中国"国家发改委十二五规划"中计划建设的大型科学装置。LHAASO共包含五种探测器阵列,对能量在1011～1015eV的广延大气簇射(Extensive Air Shower,缩写为EAS)进行连续测量。水契伦科夫探测器阵列(Water Cherenkov Detector Array,缩写为 WCDA)是 LHAASO 中的一个重要的子探测器,由分布在三个水池内的3120个光电倍增管(photomultipliertube,缩写为PMT)组成。PMT接收广延大气簇射次级粒子在水中产生的契伦科夫光并输出电信号,前端电子学模块(Front-end Electronics,缩写为FEE)接收PMT输出信号并完成电荷和时间测量,测量结果用来重建原始入射粒子的种类和入射方向。WCDA读出电子学基于分布式构架设计,FEE就近PMT放置,进行时间和电荷测量并完成数字化,数据结果进一步通过光纤长距传输至后端DAQ(DataAcquisition)。本论文研究主要集中在模拟电子学的设计上,着重研究了大动态范围情况下PMT信号的时间和电荷测量技术,基于计算分析、仿真结合试验验证的方法提出了最优化的电荷测量电路结构,并确认了电路的关键设计参数;在时间测量方面,在已有的FPGA(Field Program Gate Array)TDC(Time-to-Digital Converter)工作基础上,进一步优化设计提升了其精度指标。此外,考虑到工程实施的需求,在FEE中还设计了自动标定电路,实现了电路参数的自动标定等功能。在上述研究基础上,进行了工程样机的实际制作和系统测试。电子学测试结果表明,该工程样机在单光电子(Single Photoelectron,S.P.E.)处电荷测量精度好于8%,在4000P.E.处电荷测量精度好于1%;整个动态范围内的时间测量精度好于300 psRMS,均好于工程应用需求。最后,将工程样机分别与两种PMT进行了联合测试,测试结果均符合物理预期。此外,本论文还进一步探索了一种基于基线恢复技术的改进型前沿定时电路,在保证测量精度等性能的同时大大减小了电路死时间,为类似大动态范围下高精度定时电路提供了设计参考。本论文工作还基于本实验自主研发的放大成形电路(Pre-Amplifier and Shaping Circuit,缩写为PASC)芯片完成了另一种FEE原型电路的设计。此技术的优点是可简化前端模拟电路的复杂度。研究中也对该电路进行了初步的电子学测试以及与PMT的联合测试。本论文结构安排如下:第一章介绍了 LHAASO WCDA实验,并给出了 FEE的设计指标需求;第二章调研了目前主流的电荷和时间测量方法,并结合典型的应用实例对相关技术方案进行了分类和总结,这也是FEE工程样机的设计参考;第三章主要介绍了 WCDA FEE设计中的电荷和时间测量方案和技术路线,包括电路的计算分析、电路仿真和参数优化;第四章详细介绍了 FEE工程样机的详细电路设计与实现,包括放大成形电路、ADC电路、时间甄别电路、自动标定电路以及相应的基于FPGA的数字处理逻辑等;第五章主要介绍了 FEE工程样机的电子学测试结果。测试结果表明,各项性能指标均满足工程需求;第六章使用两种PMT与FEE原型样机进行了联合测试。测试结果均符合物理预期;第七章为论文的总结和展望。
[Abstract]:Large high altitude air shower Observatory (Large High Altitude Air Shower Observatory, abbreviated as LHAASO) is China "12th Five-Year national development and Reform Commission Plan" plans to build large-scale scientific device.LHAASO contains a total of five kinds of detector array, the energy in the 1011 ~ 1015eV extensive air shower (Extensive Air Shower, abbreviated as EAS) are continuous measuring water Cherenkov detector array (Water Cherenkov Detector Array, abbreviated as WCDA) is one of the most important sub detectors in LHAASO, by doubling the distribution of 3120 in the three photoelectric pool tube (photomultipliertube, abbreviated as PMT) consisting of.PMT received extensive air shower of secondary particles produced in water Cherenkov light and the output signal, the front-end electronics module (Front-end Electronics, abbreviated as FEE) receiving the output signal of the PMT and complete charge and time measurement, the measurement results for heavy Type and direction of.WCDA built the original incident particle readout electronics distributed architecture design based on FEE PMT, the nearest place, time and charge measurement and digital data, results in long-distance transmission through optical fiber to the back-end DAQ (DataAcquisition). This paper studies mainly focus on the design of analog electronics, focuses on the dynamic range conditions of PMT signal time and charge measurement technology, based on the calculation and analysis, put forward the optimization of the structure of charge measurement circuit simulation with the experimental method, and confirmed the key design parameters of the circuit; in time measurement, the FPGA (Field Program Gate Array) TDC (Time-to-Digital Converter) on the basis of the work further, optimization design to enhance its accuracy. In addition, taking into account the implementation of the project needs, the FEE also designed the automatic calibration circuit realization Automatic calibration function of the circuit parameters. On the basis of the above study, the actual production and system engineering prototype test. Electronics test results show that the prototype in single photo electron (Single Photoelectron, S.P.E.) the charge measurement accuracy is better than 8%, at 4000P.E. in the charge measurement accuracy of better than 1%; time measurement the precision of the dynamic range is better than 300 psRMS, were better than the requirement of engineering application. Finally, the engineering prototype with two PMT conducted a joint test, test results comply with physical expectations. In addition, this paper also further explore an improved front timing circuit baseline restoration based on ensure the accuracy of measurement of the performance of the circuit greatly reduces the dead time, provide a reference for the similar large dynamic range and high precision timing circuit. The work of this paper is based on the amplification of independent research and development (Pre-Amplifier and Shaping Circuit shaping circuit, abbreviated as PASC) chip designed another FEE prototype circuit. The advantage of this technique is to simplify the complexity of front-end analog circuit. The circuit of the study also conducted a preliminary test and combined test electronics and PMT. This paper is organized as follows: first the chapter introduces the LHAASO WCDA experiment, and gives the design index requirement of FEE; the second chapter research the charge and time measurement method of the mainstream at present, and the relevant technical schemes are classified and summarized combined with typical examples of application, which is the FEE engineering design reference prototype; the third chapter mainly introduces the charge and time measurement scheme WCDA in FEE design and technology roadmap, including the analysis of circuit calculation, circuit simulation and parameter optimization; the fourth chapter introduces the design and implementation of a detailed circuit FEE engineering prototype Now, including amplification shaping circuit, ADC circuit, time discrimination circuit, automatic calibration circuit and corresponding FPGA digital processing logic and so on; the fifth chapter mainly introduces the test results of FEE electronics engineering prototype. The test results show that the performance indexes meet the requirements of engineering; the sixth chapter uses two PMT and FEE of the prototype the joint test. The test results are in line with physical expectations; the seventh chapter is the summary and outlook of the paper.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O572.1

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