用于波长色散X射线荧光光谱仪的闪烁计数器及信号处理系统的研制

Development of a scintillator counter and signal processing system for wavelength dispersive X-ray fluorescence spectrometer

闪烁计数器(SC)是波长色散X射线荧光光谱仪(WDXRF)常用的探测器。相较于传统的闪烁计数器,通过反复试验,采用100μm的Be片作为屏蔽材料与闪烁体一体化封装,采用石英玻璃作为NaI晶体的封装材料,改善了NaI晶体的封装工艺,实现了NaI晶体的良好密封,提高了探测器的探测效率;通过电子器件定制选型,实现了对闪烁计数器输出的微弱信号的有效提取及放大,提高了探测器的能量分辨率;采用数字可调信号放大技术,实现了阳极脉冲信号放大倍数的连续可调,提高了探测器的探测范围。将上述闪烁计数器用于顺序式波长色散X射线荧光光谱仪,依照国家计量检定规程JJG 810-1993对整机进行了精密度、稳定性、探测器分辨率的测定实验。其结果为:纯铜块样品的CuKα计数值的精密度指标为0.078%,铬镍不锈钢圆块样品的NiKα计数值的稳定性指标为0.238%,探测器能量分辨率指标为39.73%,均达到该检定规程中A级指标要求。

The scintillation counter(SC)is a commonly used detector for the wavelength dispersive X-ray fluorescence spectrometer(WDXRF).Compared with the traditional scintillation counters,by trial and error,100μm Be sheet was used as the shielding material to integrate with the scintillator.Meanwhile,the quartz glass was selected as the packaging material of NaI crystal.It improved the packaging technology of NaI crystals,realizing the good sealing of NaI crystals and enhancing the detection efficiency of the detector.Through the customized selection of electronic components,the weak signal output from the scintillation counter was effectively extracted and amplified,which improved the energy resolution of the detector.The digital adjustable signal amplification technology was used to achieve the continuously adjustable amplification of the anode pulse signal,and the detection range of the detector was increased.The obtained scintillation counter was used for a sequential wavelength dispersive X-ray fluorescence spectrometer.The precision,stability and detector resolution experiments were performed on the whole machine according to the national metrological verification regulations JJG 810-1993.The results showed that:the precision index of the count value of CuKαwas 0.078% for the pure copper billet sample;the stability index of the count value of NiKαwas 0.238% for the chromium nickel stainless steel sample;the energy resolution index of detector was 39.73%.All these indexes could meet the A-level requirements in this verification regulation.