基于FPGA的全数字双通道符合多普勒展宽系统  

Full digital dual channel coincidence Doppler broadening system based on FPGA

作　　者：钱秋妃 王柱[1] 黄启俊[1] 邹风华 廖远 张梦新 Qian Qiufei;Wang Zhu;Huang Qijun;Zou Fenghua;Liao Yuan;Zhang Mengxin(School of Physics and Technology,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学物理科学与技术学院

出　　处：《电子技术应用》2020年第3期97-100,共4页Application of Electronic Technique

基　　金：国家重点研发计划(2017YFF0106506);国家自然科学基金项目(11575129)

摘　　要：针对核辐射能谱、正电子湮没符合多普勒展宽谱测量的需求,设计了一种基于FPGA的全数字双通道符合多普勒展宽系统。该系统以16 bit模数转换芯片AD9269-80为前端,将高纯锗探测器采集到的模拟信号转化为数字信号,该数字信号进入系统后端的FPGA芯片中进行数字处理。FPGA通过滑动平均窗口、乒乓操作、自定义IP核等实现对核脉冲信号的处理,包括波形降噪、梯形滤波、基线恢复、堆积识别、阈值判断、数据缓存等,从而得到核脉冲的幅度信息和时间信息。再由网口模块与上位机之间进行通信,采用UDP协议进行幅度、时间信息的传输,得到核信号的能谱。系统采用双通道对正电子符合多普勒展宽谱测量,得到二维符合图谱。Aiming at the requirement of nuclear radiation spectrum and positron annihilation coincidence Doppler broadening spectrum measurement, an all digital dual channel coincidence Doppler broadening system based on FPGA is designed.In this system,the analog signal collected by the high purity germanium detector is converted into digital signal by the front-end of 16 bit analog-to-digital conversion chip AD9269-80.The digital signal enters the FPGA chip at the back-end of the system for digital processing.FPGA realizes the processing of nuclear pulse signal through moving average window, ping-pong operation, custom IP core,etc., including waveform noise reduction, trapezoid filtering, baseline recovery, stack recognition, threshold judgment, data cache,etc., so as to obtain the amplitude information and time information of nuclear pulse.Then, the communication between the network port module and the upper computer is carried out, and the amplitude and time information are transmitted by UDP protocol to obtain the energy spectrum of the nuclear signal.The system uses two channels to measure the broadening spectrum of positron coincidence Doppler and obtains two-dimensional coincidence spectrum.

关 键 词：正电子湮没辐射多普勒展宽 FPGA 双通道 梯形滤波 

分 类 号：TN911.7[电子电信—通信与信息系统] TP274.2[电子电信—信息与通信工程]