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摘要：NaI(Tl)能谱仪探测效率高，装置成本低、使用方便，易于文护等多方面优势，在放射性监测中被广泛应用。但是因NaI(Tl) γ能谱仪能量分辨率低，在核素含量低、种类多、介质复杂，本底等众多因素干扰的测量环境下，会造成许多低能区能量相近的全能峰叠加在一起，影响γ能谱分析结果的不确定性。22642
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精确地计算出各个特征峰的峰位是γ能谱分析中的关键问题，根据峰位对应的能量可以定性识别被测样品中的核素种类。γ谱的寻峰方法有多种，如匹配滤波器方法、导数法、协方差法和函数拟合法等。其本质是对能谱数据进行高通滤波，只不过其滤波器系数的和为0。本文针对NaI(Tl)和LaBr3(Ce)探测器便携式器γ谱仪特点，主要讨论导数寻峰方法和对称零面积寻峰方法。
1、导数寻峰方法就是利用函数极大值的一、二、三阶导数的特点，进行寻峰。二阶导数寻峰法由于其较强的分辨重峰的能力、寻找弱峰的能力以及抑制假峰的能力，成为了最常用的寻峰方法。
2、对称零面积法是用面积为零的窗函数与实验数据进行卷积变换，并且要求窗函数为对称函数。
通过对实测γ能谱的分析可以看出：对于弱峰，数据光滑前，高斯乘积函数法和协方差法不能使用，若先光滑再找峰，又容易影响重叠峰的分辨；而导数法和对称零面积变换法，无论峰的统计质量如何，均可使用。从统计假峰及高基底的抑制能力及重峰的分辨能力来看，一、三阶导数法和对称零面积变换法是较好的。对于一、三阶导数法，可先用适当多数据点的一阶导数法找峰，选取适当的灵敏度常数，以抑制假峰；然后用少点的三阶导数法（或用一阶导数法重复三次）检查是否有漏峰和重峰。对称零面积变换法同理。从高基底的抑制能力和弱峰识别的准确度来看，对称零面积变换法最好。（在计算机自动找峰程序中，最好采用对称零面积变换法。）
毕业论文关键字: γ能谱；解谱；寻峰；算法；函数拟合
Gamma spectrum peak search algorithm design
Abstract：NaI (T1) γ spectrometer has many advantages, such as high efficiency of the detection, low cost device, easy to use and easy maintenance, It is has been widely used in the radiation monitor. But it also has the shortcoming, such as low resolution, especially in the low radionuclide content, many kinds of backgrounds interfere measurement conditions , many peaks in low energy areas cause overlaps, all of which lead to the uncertain results of γ spectral analysis.
Accurately calculate the characteristic peaks of each bit is γ spectrum analysis of the key issues, according to the peak corresponding to the energy can be qualitatively identify the radionuclide species in the sample. γ spectrum peak search a variety of methods, such as the matched filter method, derivative method, covariance method and function fitting and so on. Its essence is a high-pass filtering the data spectrum, but its filter coefficients and is 0. In this paper, NaI (Tl) and LaBr3 (Ce) portable device γ spectrometer detector characteristics, discusses derivative peak search methods and symmetrical zero-area peak search methods.
1 . Derivative peak search function maxima method is to use one, two, features the third derivative of conduct peak search. Second derivative peak search method due to its ability to distinguish doublets strong, looking weak peaks and the ability to suppress false peak, becoming the most common peak search methods.
2. Symmetrical zero-area method is to use a window function with the experimental data convolution transform an area of zero and requires a window function is symmetric functions.