γ能谱级联符合相加效应校正技术研究进展

Research progress on correction techniques for coincidence summing effect inγ-ray spectrometry

使用γ谱仪近距离测量具有级联衰变关系的放射性核素时会不可避免地发生级联符合相加效应。级联符合相加效应会导致能谱中的全能峰计数变化,并产生干扰能谱分析的加和峰,从而影响γ能谱分析的准确性和效率,为此,国内外研究机构建立了多种方法和技术用于γ能谱级联符合相加效应的校正。本文在详细总结级联符合相加效应校正技术发展历程的基础上,对级联符合相加效应的产生机制、校正算法、校正软件、技术应用等进行了综述,并对不同校正算法和软件进行了比较。结合发展现状,对级联符合相加效应校正技术今后的研究方向提出了建议。

As a passive nondestructive nuclear technique,gamma ray spectrometry is used in many radioactivity laboratories.Gamma-ray spectrometry enables the identification of radionuclides in a sample from their emitted photon energy and calculation of their activities from the number of photons collected for each energy.However coincidence summing effects will influence the reliability of both radionuclide identification and calculation of activity.Coincidence summing effects appear when sources emitting coincident gamma rays are measured via gamma-ray spectrometry.Those effects that result in losses from the full energy peaks and enhancement of sum peaks influence the accuracy of the spectral analysis.To eliminate this influence,many correction methods have been established.Research on the coincidence summing effect(CSE)originated in the 1960s.Subsequently,many algorithm-based generation mechanisms of CSE have been built together with the development of corresponding correction software.Massive amounts of technological information on and achievements about coincidence summing correction have been reported by researchers from different countries,hence several intercomparisons of these methods,and self-consistency testing of cascaded additive effect correction algorithm were organized by the International Committee for Radionuclide Metrology(ICRM).Based on a detailed summary of the development history of correction methods,the CSE mechanisms,correction algorithms,correction software,and application of correction techniques were reviewed in this paper.Cobalt-60 was taken as an example to illustrate the influence of the summing-in and summing-out effects,with correction equations based on different measurement geometries and considering the impact of angular correlations.Meanwhile,the performance of different algorithms and software were compared and analyzed.Combined with the current research status,some suggestions are presented for future research for domestic researchers on the coincidence summing effect correction.First,the efficiency must be accurately established for the geometrical conditions of the measurement.Second,the number of cascades in the algorithm must be taken into account owing to its influence on the results.Third,correction software with a userfriendly interface and database of accurate decay schemes should be developed.