Jia Wen-Bao, Zhang Yan, Hei Da-Qian, Ling Yong-Sheng, Shan Qing, Cheng Can
Guang Pu Xue Yu Guang Pu Fen Xi. 2014 Nov;34(11):3123-6.
In the present paper, a new combined detection method was proposed using prompt gamma neutron activation analysis (PGNAA) and characteristic X-ray fluorescence to improve the heavy metals measurement accuracy for in-situ environmental water rejects analysis by PGNAA technology. Especially, the characteristic X-ray fluorescence (XRF) of heavy metals is induced by prompt gamma-ray directly instead of the traditional excitation sources. Thus, a combined measurement facility with an 241 AmBe neutron source, a BGO detector and a NaI-Be detector was developed to analyze the pollutants in water. The two detectors were respectively used to record prompt gamma-ray and characteristic X-ray fluorescence of heavy metals. The prompt gamma-ray intensity (I(γ)) and characteristic X-ray fluorescence intensity (I(x)) was determined by MCNP calculations for different concentration (c(i)) of chromium (Cr), cadmium (Cd), mercury (Hg) and lead (Pb), respectively. The simulation results showed that there was a good linear relationship between I(γ), I(x) and (c(i)), respectively. The empirical formula of combined detection method was given based on the above calculations. It was found that the combined detection method was more sensitive for high atomic number heavy metals like Hg and Pb measurement than low atomic number like Cr and Cd by comparing and analyzing I(γ) and I(x). The limits of detection for Hg and Pb by the combined measurement instrument were 17.4 and 24.2 mg x kg(-1), respectively.
在本文中，提出了一种新的联合检测方法，即使用瞬发伽马中子活化分析（PGNAA）和特征X射线荧光来提高利用PGNAA技术进行原位环境水体废弃物分析时重金属测量的准确性。特别是，重金属的特征X射线荧光（XRF）由瞬发伽马射线直接激发，而非传统激发源。因此，开发了一种配备241AmBe中子源、BGO探测器和NaI-Be探测器的联合测量设备，用于分析水中的污染物。这两个探测器分别用于记录重金属的瞬发伽马射线和特征X射线荧光。通过MCNP计算分别确定了不同浓度（c(i)）的铬（Cr）、镉（Cd）、汞（Hg）和铅（Pb）的瞬发伽马射线强度（I(γ)）和特征X射线荧光强度（I(x)）。模拟结果表明，I(γ)、I(x)与c(i)之间分别存在良好的线性关系。基于上述计算给出了联合检测方法的经验公式。通过比较和分析I(γ)和I(x)发现，联合检测方法对于测量像Hg和Pb这样高原子序数的重金属比像Cr和Cd这样低原子序数的重金属更灵敏。联合测量仪器对Hg和Pb的检测限分别为17.4和24.2 mg x kg(-1)。
