~(238)Pu低能光子源衰变γ能谱识别

利用同轴P型高纯锗探测器,对X荧光分析的~(238)Pu低能光子源进行γ能谱分析,并对~(233)Pa、~(224)Ra、~(212)Pb、~(212)Bi及~(208)Tl的特征γ射线进行分析,确定上述核素的来源。其中,~(233)Pa是生产~(238)Pu的原料237 Np的衰变产物,~(224)Ra、~(212)Pb、~(212)Bi及~(208)Tl均为生产~(238)Pu的副产物~(236)Pu的衰变子核。能量为350、440、844、1 014、1 130、1 266、1 368、1 454keV的γ射线是α粒子轰击源封装材料引起原子核库伦激发或γ射线照射周边环境引起核激发产生。进行效率刻度后,使用γ能谱法计算各放射性核素的活度,并根据放射性平衡计算各放射性核素的质量。通过对~(238)Pu源γ能谱的分析,建立计算放射性同位素活度与质量的方法。

Identification of Gamma Spectrum Decayed by 238Pu as a Low Energy Photon Source

The gamma spectrum of 238 Pu low energy photon source which was used for X-ray fluorescence analysis was analyzed by using P-type coaxial HPGe detector .There were characteristic rays of 233 Pa ,224 Ra ,212 Pb ,212Bi and 208 Tl in the spectrum except the characteristic gamma rays of 238 Pu .233 Pa was the decay product of 237 Np ,which was the raw material used to produce 238Pu .224Ra ,212Pb ,212Bi and 208Tl were the daughter nuclei of 236 Pu ,which was by-product in the process of 238 Pu's production .Gamma rays of 350 ,440 ,844 ,1014 ,1130 ,1266 ,1368 ,1454 keV were caused by coulomb exci-tation that alpha particles bombarded encapsulation materials of the source ,or nuclear excitation that gamma rays irradiated surroundings .After the basis of efficiency calibra-tion ,the radioactive activity of each radioactive nuclide was calculated by gamma ray spectrometry .The quality of each radioactive nuclide was calculated derived from the principle of radioactive equilibrium .Through the analysis of 238 Pu's gamma ray spec-trum ,the method to calculate the radioisotope activity and the purity of radioactive sources was offered .