中文摘要：

针对不同淬灭水平混合90Sr/90Y液闪谱，利用Origin软件建立了基于非对称双S函数的简易拟合方法。由于常用外标准淬灭指数受外标准谱的统计涨落影响（测定高活度样品时可能会产生显著误差），因此根据90Y样品液闪谱特征自定义了不受样品活度影响的淬灭指数。利用该淬灭指数和不同淬灭水平90Y样品的液闪谱，将90Y液闪谱位置和形状参数与自定义淬灭指数进行关联，并在此基础上完成了不同淬灭水平混合90Sr/90Y液闪谱的解析，解析结果与实验结果符合良好。该法有望用于同时测定不同淬灭水平样品中几种放射性核素的活度。

英文摘要：

On the basis of the asymmetric double sigmoid function, a simple method was developed to fit the LSC （liquid scintillation counting） spectra of mixed 90Sr/90Y samples under different quench levels using the software Origin. Because the external standard quench index is usually affected by the statistical fluctuations significantly for a sample with high radioactivity, a quench index is defined, which is based on the characteristics of 90y spectrum and will not change with the sample radioactivity. The defined quench index has been correlated with the parameters which reflect the position and shape of the 90y spectra. Based on the correlation, the LSC spectra for mixed 90Sr/90y samples under different quench levels have been fitted, showing good agreement with the results from experiment. This method is promising to be applied to simultaneously determine the radioactivities of several radionuclides under different quench levels by LSC.