【作者】 吴伟；

【导师】 鄢秋荣； 赵宝升；

【作者基本信息】 南昌大学 ， 电子信息（专业学位）， 2024， 硕士

【摘要】 “天格计划”(Gamma Ray Integrated Detectors,GRID)是由清华大学发起的一个空间科学项目,主要科学目标是利用立方星载荷探测伽马射线暴以及其它天体物理瞬变源。硅光电倍增管(Silicon photomultiplier,SiPM)因其具有探测效率高、体积小、工作电压低和对磁场不敏感等特性,成为高能光子的光检测优选技术,是作为立方星载荷探测器的优选方案。结合多个SiPM组成的阵列能够有效叠加输出信号的幅度值,但SiPM阵列输出的高速信号传输时灵活性不高且效率低下,而现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)具有高度灵活的硬件并行性、可编程性和可配置性等优点,能够有效解决上述问题。本文面向南京大学“天格计划”中第二颗立方星载荷探测器电子学系统进行研究,并通过对SiPM阵列探测器电子学系统硬件电路和FPGA逻辑进行设计,实现了一种SiPM阵列+高速ADC+FPGA的探测器电子学系统。主要工作内容和研究成果如下:(1)设计并完成了SiPM阵列及其偏置电压电路。在偏压控制方面,首先PC端通过串口发送指令来控制DAC芯片输出的电压值(其电压调节的精度达到9 mV),接着此电压值被高压电源芯片接收后给SiPM提供一个稳定并可调节的偏置电压;在SiPM阵列电路方面,采用4×4 SiPM的阳极叠加输出,16个阴极接偏置电压供电。同时,在黑暗密闭条件下,通过控制不同强度的光照对工作在29 V的SiPM阵列进行测试,测试得到了快速上升后缓慢衰减的脉冲信号,其幅值为318 mV,与理论上输出的波形结果一致,验证了SiPM阵列输出设计的可行性。(2)设计了SiPM探测器读出电路。包括电源电路、时钟电路、前端多级放大电路、单端转差分电路、数据采集电路、FPGA及其外设电路等。对SiPM探测器读出电路进行PCB设计与制板,再进行硬件测试,结果表明各个芯片均正常工作。(3)搭建了一套SiPM阵列探测器电子学系统,设计了一种基于FPGA的多通道能谱采集方案。本文通过产生一种到达时间和幅度均随机的仿核脉冲信号源,用来模拟高能光子信号输出。经ADC采集后,通过存储FIFO中的信号幅值进行比较,并在检测到峰值后求解能量。在此过程中,以能量为道址,得到了统计能谱。经分析,仿真与测试结果一致,验证了探测器电子学系统的可行性。更多还原

【Abstract】 Gamma Ray Integrated Detectors(GRID)is a space science project initiated by Tsinghua University,the main scientific goal of GRID is to detect gamma-ray bursts and other astrophysical transients using cubesat payload detector.Silicon photomultiplier(SiPM)has become the preferred technology for high energy photon detection due to its high detection efficiency,small size,low operating current and insensitive to magnetic field,and is the preferred scheme for cubesat payload detector.The array composed of multiple SiPM can effectively superposition the amplitude value of the output signal,but the high-speed signal transmission of the output of SiPM array is not flexible and inefficient,and Field Programmable Gate Array(FPGA)has the advantages of highly flexible hardware parallelism,programmability and configurability,which can effectively solve the above problems.In this paper,the electronics system of the second cubesat payload detector in Nanjing University GRID is studied,and by designing the hardware circuit and FPGA logic of the electronics system of SiPM array detector,a detector electronics system of SiPM array + high-speed ADC+ FPGA is realized.The main work contents and research achievements are as follows:(1)The SiPM array and its bias voltage circuit are designed and completed.In terms of bias control,first of all,the PC sends instructions through the serial port to control the output voltage value of the DAC chip(the accuracy of voltage regulation reaches 9 mV),and then the voltage value is received by the high-voltage power supply chip to provide a stable and adjustable bias voltage for the SiPM;In the SiPM array circuit,the anode stack output of 4×4 SiPM is used,and 16 cathodes are supplied with bias voltage.At the same time,the SiPM array working at 29 V was tested by controlling different intensifies of light under dark and closed conditions,and the pulse signal with a amplitude of 318 mV was obtained,which was consistent with the theoretical output waveform and verified the feasibility of the output design of SiPM array.(2)The readout circuit of SiPM detector is designed.It includes power supply circuit,clock circuit,front-end multistage amplifier circuit,single-end conversion differential circuit,data acquisition circuit,FPGA and its peripheral circuit,etc.PCB design and fabrication of SiPM detector readout circuit were carried out,and then hardware test was carried out.The results show that each chip works normally.(3)An electronic system of SiPM array detector is constructed,and a multi-channel energy spectrum acquisition scheme based on FPGA is designed.In this paper,a nucleoid pulse signal source with random arrival time and amplitude is generated to simulate the output of high energy photon signals.After being collected by the ADC,the signal amplitude in the FIFO is compared by storing it,and the energy is solved after the peak value is detected.In this process,the statistical energy spectrum is obtained with the energy as the address.The simulation results are consistent with the test results,and the feasibility of the detector electronics system is verified.更多还原