为研究样品微颗粒在X射线荧光（XRF)分析中对测量结果的影响, 运用蒙特卡罗模型MCNPX对X射线荧光仪进行建模, 研究了样品颗粒粒径对X射线荧光特征峰强度、 峰总比和源峰探测效率的影响, 并设计波长色散X射线荧光光谱法（WDXRF)分析实验对模拟结果进行了检验。 结果表明: 对于样品微颗粒X射线荧光强度与粒径尺寸的关系, MCNPX模拟值与理论计算值保持一致; MCNPX模拟结果与WDXRF实验结果存在一定差异, 这取决于MCNPX模型对待测样品状态的假设与实际情况存在一定的差异性; 运用样品粉碎、 研磨至小颗粒并进行压片处理的办法, 可使WDXRF实测结果尽可能的减小与MCNPX理论模拟结果的差异性; 在待测样品的颗粒粒径达到一定尺寸时, 其峰总比、 源峰探测效率、 特征峰X射线荧光计数均趋于稳定值; 颗粒粒径在某一特定尺寸范围之内, 颗粒度效应的影响不容忽视; 除此之外, 颗粒度效应的影响基本可以忽略。 论文充分考虑了待测样品颗粒粒径对XRF分析结果的影响, 为减小因颗粒度效应引起分析结果的不确定性提供了一种可行的研究思路, 该方法也可为X射线分析的生产实践提供一定的技术参考。

In order to research the effectof X-ray fluorescence (XRF) analysis on the results in the sample’s micro particles, MCNPX models had been established for an X-ray fluorescence analyzer in this paper. It had studied the characteristics of the samples with different particle sizes, the fluorescence peak counts, the peak to total ratios and the peak to source ratios. A micro particle analysis experiment had been designed for its verification. The results showed that: as for the relationship between the fluorescence intensity and the particle sizes, the MCNPX calculations were consistent with the theoretical, but contrary with the experimental results; the reason is that some hypotheses about samples in the MCNPX models were contrary with the actual states; the samples were crushed by grinding to small particles and tableting process, the MCNPX calculations and experimental results can be conversion; when the particle sizes of the samples reached the certain sizes, the fluorescence peak counts, the peak to total ratios and the peak to source ratios were stable value; within a particular size range, the influence of the particle size effects cannot be ignored, otherwise this influence can be ignored. The research methods and conclusions in this paper can provide a technical reference guide for X-ray analysis in practices.