Due to the compositional variation of the sample, linear relationship between the element concentration and fluorescent intensity will not be well maintained in most X - ray fluorescence analysis. To overcome this, we use MCNP program to simulate fluorescent intensity of Fe (0 ~ 100% concentration range) within binary mixture of Cr and O which represent typical strong absorption and weak absorption conditions respectively. The theoretic calculation shows that the relationship can be described as a curve determined by parameter p and value of p can be obtained with given absorption coefficient of substrate elements and element under detection. MCNP simulation results are consistent with theoretic calculation. Our research reveals that MCNP program can calculate the Calibration Curve of X - ray fluorescence very well.%X射线荧光分析中,由于物质成分变化对检测结果的影响,在多数情况下元素浓度含量和荧光强度间不是线性对应关系.针对0～100%浓度的Fe和基体为Cr(强吸收体)和O(弱吸收体)的二元混合物样品,使用MCNP程序模拟强吸收和弱吸收时Fe的荧光强度和Fe的浓度的对应关系.理论表明该对应关系为由参数p确定的曲线,p值由基体元素和待测元素对射线的吸收系数确定.MCNP计算结果和理论公式一致,应用MCNP程序可以计算荧光分析基体效应的校正曲线.
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