环境辐射监测数字伽玛谱仪设计

摘要

The design of digital gamma -ray spectrometer for environmental radiation monitoring has been pres-ented.It detects gamma ray by NaI(Tl) gamma-ray detector.FPGA plays very import role in logical control and digital low pass FIR filter .FPGA controls programmable gain amplifier ( PGA) to adjust the amplitude of nuclear pulse signal .After high speed ADC acquiring nuclear pulse signal , FPGA filters the digital signal by Hamming window FIR low-pass digital filter .And then DSP ( TMS320 C6713 ) is responsible for digital pulse trapezoidal Shaping , which can reduce pulse pile up and ballistic deficit , peak detecting , and obtaining spec-trum.After calibration, the spectrometer can not only get the total count , but also roughly discriminate nu-clides, which is meaningful to spot radiation monitoring in industrial areas .The design is very smart and scala-ble to meet spot radiation monitoring .%本文介绍了一种环境辐射监测数字伽玛谱仪设计方案。本设计采用NaI（ Tl）探测器对伽玛射线进行探测，由FPGA控制可编程增益放大器对核脉冲信号进行调节，以适合后续模数转换输入要求。由FPGA控制高速模数转换器AD9235对核脉冲信号进行模数转换，然后采用海明窗低通FIR数字滤波器对数字核脉冲信号进行滤波，滤除高频噪声。本设计采用TMS320 C6713对数字核脉冲信号进行梯形成形，改善弹道亏损和脉冲堆积，最后对其进行幅值判断形成能谱。谱仪经刻度后，不仅可以获得现场辐射计数总量还可以获取现场能谱对核素进行初步判别，这对于工业环境辐射监测非常有意义。本设计具有体积小、设计灵活、可扩展性好等特点，非常适合现场环境辐射监测。