Levenberg-Marquardt高斯拟合法在NaI(Tl)γ谱分析中的应用

The Application of the Levenberg-Marquardt Gaussian Fitting Method in NaI(Tl) γ Spectrum Analysis

为提高γ谱法测定核素活度的准确性,采用高斯函数对除本底后的峰区进行峰形拟合,并根据Levenberg-Marquardt法对拟合方程进行求解得出峰形参数。该方法是以预处理所得峰高、峰位和峰宽为初值,并自适应计算步长进行迭代直至迭代完毕。根据计算仿真结果分析,该方法能够将单能峰拟合到最佳状态,且能将重叠峰分离成多干单峰并拟合。实验表明,该方法可快速准确地计算特征峰峰面积,所得核素特征峰面积与HPGe谱仪所测峰面积相对误差小于8%。

In gamma spectroscopy analysis, in order to improve the accuracy of the radionuclide activity, the net count of the radionuclide characteristic peaks is particularly important. The paper adopted the Gaussian function fitting the peak shape of the peak area after subtracting the background of the peak area, and the paper gets the peak shape parameters by solving the fitting equation according to the Levenberg - Marquardt method, this method takes the pretreatment resultant peak height, peak position and peak width as the initial value, and adap- tive computes step size to iterate until the iteration is completed. Analyzing according to the computational sim- ulation results, this method can fit mono - energetic peak to the best state, and the overlapped peaks can be separated into multiple single peak then do fitting. Through the experiment, the relative error between the above method measured nuclides characteristic peak area and the HPGe spectrometer measured peak area is less than 8 %, the experimental results show that this method can rapidly and accurately calculate the characteristic peak area,