高集成度自动化γ能谱仪

Highly integrated automated γ spectrometer

摘要:

针对核反应堆安全壳内γ射线在线监测需求，本文设计了一款高集成度、低功耗、高分辨、长续航、可自动测量的γ能谱仪. 谱仪选用了高分辨率LaBr3(Ce)闪烁体探测器，并且设计了有源锥形分压电路为探测器供电，从而提高谱仪的能量响应动态范围. 同时设计了低噪声电荷灵敏前置放大器电路对探测器输出信号进行放大，并匹配设计二阶有源低通滤波电路，将前端信号成形为准高斯脉冲信号. 采用STM32L4系列微处理器设计了高集成度的多道脉冲幅度分析电路，完成脉冲信号的模数转换和在线数据处理，获得γ能谱. 另外，本文还基于CC228P-09Y小型高压电源模块设计了低噪声高压电源电路为LaBr3(Ce)探测器提供高压；利用STM32L4处理器设计了锂电池供电的电源管理电路，使得谱仪可以实现自动开启工作模式或进入待机模式，从而实现长续航时间自动γ能谱测量功能. 对谱仪进行性能测试得到：谱仪能量分辨率为3.0%（@662 keV），且能量响应积分非线性为9.5%，能够长期稳定工作，具有低功耗长续航时间等特点.

Abstract:

With respect to the need for online γ-ray monitoring in the containment of nuclear reactors, a γ spectrometer with high integration, low power consumption, high energy resolution, long endurance and automatic measurement is designed in this paper. A LaBr3(Ce) scintillator detector with high energy resolution is used in the spectrometer. And an active cone-shaped voltage divider circuit is designed to supply power to the detector and to improve the dynamic range of energy response of the spectrometer. Additionally, a low noise charge-sensitive preamplifier circuit is designed to amplify output signal of detector, and a second-order active low-pass filter circuit is designed to shape the front-end signal into a quasi-Gaussian pulse signal. A high integrated multi-channel pulse amplitude analysis circuit is designed by using STM32L4 series microprocessor to complete the analog-to-digital conversion and on-line data processing of the pulse signal and obtain γ energy Spectrum. In addition, we also designed a low-noise high-voltage power supply circuit based on the CC228P-09Y small high-voltage power supply module to provide high voltage for the LaBr3(Ce) detector. The power management circuit powered by lithium battery is designed by using STM32L4 series processor, thus the spectrometer can enter the working mode or standby mode automatically, realizing the automatic γ spectrum measurement function of long endurance time. In the end, a detailed performance test of the spectrometer is carried out: the energy resolution of the spectrometer is 3.0% (@ 662 keV), and the energy response integral nonlinearity is 9.5%. It can work stably for a long time and has the characteristics of low power consumption and long endurance time.