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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 study the influence of the sample microparticles on the measurement results in the X-ray fluorescence (XRF) analysis, the X-ray fluorescence spectrometer was modeled by the Monte Carlo model MCNPX. The effect of the sample particle size on the X-ray fluorescence peak intensity, Which is better than the detection efficiency of the source peak, and the design of wavelength dispersive X-ray fluorescence spectrometry (WDXRF) was used to test the simulation results. The results show that the simulated value of MCNPX is consistent with the theoretical value for the relationship between the X-ray fluorescence intensity and particle size of the sample. The difference between the MCNPX simulation result and the WDXRF experimental result depends on the MCNPX model’s hypothesis of the sample state And the actual situation there is a certain difference; the use of sample crushing, grinding to small particles and tabletting approach, WDXRF measured results can be as much as possible to reduce the MCNPX theoretical simulation results of the differences; the particles in the sample to be tested When the particle size reaches a certain size, the total peak ratio, the detection efficiency of the source peak and the characteristic peak X-ray fluorescence count tend to be stable. The particle size within a certain size range, the influence of the particle size effect can not be ignored; except In addition, the effect of granularity can be neglected. Papers take full account of the particle size of the sample under test XRF analysis results, in order to reduce the particle size effect caused by the uncertainty of the analysis results provide a viable research ideas, the method can also be used for X-ray analysis of production Practice to provide some technical reference.