Study Of Analyzing Techniques For γ Spectra From Nuclear Material Based On Genie Algorithm

γspectrum analysis is one of the most important technologies to probe and analyze nuclear materials, and it is used wildly in nuclear safeguard field. The basic task ofγspectrum analysis is to do qualitative analysis and quantitative analysis of radioactive nuclides in nuclear material. Generally, qualitative analysis means to making sure the kinds of radioactive nuclides in nuclear material according to the positions of full energy peaks inγspectrum; quantitative analysis means to calculate the radio activities of nuclides in nuclear materials according to strength of ingredient in the spectrum (full energy peak area) on the basis of qualitative analysis.An integrateγspectrum includes full energy peaks, escape peaks, annihilation peaks, retro diffusion peaks, coincidence peaks, Compton diffusion spectrum and so on. Because of the complexity ofγspectrum ingredient, there are many serious overlaps and interruptions. That makes a lot of difficulties to calculate the full energy peak area in quantitative analysis. Usually, a routineγspectrum analysis software can not satisfy technical requirements with the development of nuclear ethnics and applications, especially on the complexγspectrum analysis of nuclear warhead materials. Routineγspectrum analysis software can not get the attainable precision.According to the linear additivity ofγspectrometer system, this thesis put forward a new method- theγspectrum analysis based on Genie Algorithm. This method improves the operating factor ofγspectrum based under least squares technique-idea and the object is wholeγspectrum. It optimizes the overall situation by using theγspectrum analysis based on Genie Algorithm. It pulls into corrected parameters ofγspectrum drift. So it achieves to correct the spectrum drift by software. At the same time, it can get more precise values by putting related coefficient of fitting spectrum and objective function into Genie Algorithm fitness function.Firstly, this thesis proves the feasibility of the method by analyzing the simulation spectra of Monte Carlo techniques. Many kinds of discrete and mixedγspectra of standard radioactive sources were simulated by Monte Carlo method. We analyzed the mixed spectra by using the discrete spectra as standards quantitatively, and achieved higher precision. It is proved that the method is feasible.Secondly, we studied the low limit of quantitative analysis and energy resolving capability of the method by analyzing the Monte Carlo simulation spectra. According to the research, we can see that this method has good capability of energy resolution, and the precision of analysis be not influenced by the effect of overlap peaks almost, especially, this method adoptedγspectrum analysis of many nuclides with weak peaks and coincidence peaks. It shows that this method have lower limit of quantitative analysis. Finally, this thesis proves the practicability of this method by analyzing the HPGeγspectra. We collected the spectra of standard radioactive sources- ¹³⁷Cs, ⁶⁰Co and ¹⁵²Eu in lab, and get the discreteγspectra and mixed spectra. Then we analyzed the mixed spectra quantitatively by using the discreteγspectra as standards. This method gives higher accurate results in realγspectra analysis, and the errors are under 2.5%, it shows that theγspectra analysis based on Genie Algorithm is effectual and feasible.