提出了基于平移不变离散小波变换(Translation Invariant Discrete Wavelet Transform,TI—DWT)小波模极大值空间选择性滤波(Translation Invariant Discrete Wavelet Transform Wavelet Modulus Maxima Spatial Selectivity Filter,TI-DWT-MSSNF)的能谱平滑算法,并构建了光滑效果评价指标。分别使用α谱仪和γ谱仪获取了^239Pu、^241Am的α能谱和^137Cs的γ能谱,将5点3次多项式最小二乘法、传统的小波模极大值法和TI-DWT-MSSNF分别用于α和γ,谱平滑处理。结果表明:相比较5点3次多项式最小二乘法和传统的小波模极大值法,TI—DWT-MSSNF消除统计涨落更加彻底,特征信息保留更好,峰形畸变更小,是一种更优的方法。
Background: Nuclear decay, electronic noise, statistic fluctuations, etc., exist inherently. Therefore, the measured spectrum always has statistic fluctuation. Purpose: In order to reduce the statistical fluctuation and electronics noise in detector, translation invariant discrete wavelet transform (TI-DWT) wavelet modulus maxima spatial selectivity filter (TI-DWT-MSSNF) smoothing algorithm was put forward to preprocess data for the de-convolution of spectrum. Methods: The a-spectrum was acquired by using ORTEC-8 channel α spectrometer to measure the source numbered AMPU1103 (239pu and 241Am) under vacuum conditions of-0.03 MPa. The γ-spectrtun was obtained by using γ spectrometer and 137Cs source. Cubical smoothing algorithm with five-point approximation ("5-3"), the traditional method of wavelet modulus maxima (WTMM) and TI-DWT-MSSNF were applied to smooth α and γ spectra. Results: The study showed that TI-DWT-MSSNF method could eliminate statistical fluctuation more thoroughly, retain feature information better compared with "5-3" and WTMM. The D(r) values of TI-DWT-MSSNF were greater and Z2 values of TI-DWT-MSSNF were more close to 1 compared with those of "5-3" and WTMM. Conclusion: Comprehensive research indicates that it is feasible to reduce the statistical fluctuations of spectrum using TI-DWT-MSSNF. And TI-DWT-MSSNF outperforms both the "5-3" and WTMM.