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放射性氙同位素(~(131)Xe~m、~(133)Xe~m、~(133)Xe和~(135)Xe)具有化学惰性、裂变产额大、易释放的特点,是监测核试验尤其是地下核试验最关键的核素之一。~(131)Xe~m和~(133)Xe~m的γ射线发射概率小,X射线能量完全相同,致使HPGeγ能谱法测量~(131)Xe~m和~(133)Xe~m活度的探测灵敏度低。针对这一技术难题,本文研究建立了~(131)Xe~m和~(133)Xe~m活度测量的X/γ射线交互分析方法。利用贝叶斯方法推导了γ能谱中净峰面积概率分布,根据得到的~(131)Xe~m和~(133)Xe~m X射线和γ射线净峰面积分布构建了活度分布的似然函数,采用最大似然法得到了~(131)Xe~m和~(133)Xe~m活度。相对于仅用γ射线分析,提高了~(131)Xe~m和~(133)Xe~m的探测灵敏度。
Radioactive xenon isotopes (~ (131) Xe ~ m, ~ (133) Xe ~ m, ~ (133) Xe and ~ (135) Xe) are chemically inert and have large fission yield and are easy to release. In particular, one of the most critical nuclides for underground nuclear testing. The γ-ray emission probability of ~ (131) Xe ~ m and ~ (133) Xe ~ m is small and the X-ray energies are exactly the same, which leads to the measurement of ~ 131 Xe ~ m and ~ 133 Xe ~ m by HPGe γ spectroscopy Degree of detection sensitivity is low. In response to this technical problem, this paper studies the X / γ ray interaction analysis of ~ (131) Xe ~ m and ~ (133) Xe ~ m activity measurements. The Bayesian method was used to derive the net peak area probability distribution in γ spectra. Based on the obtained net peak area distributions of ~ (131) Xe ~ m and ~ (133) Xe ~ m X-rays and γ-rays, The likelihood function, ~ (131) Xe ~ m and ~ (133) Xe ~ m activity were obtained by the maximum likelihood method. The detection sensitivity of ~ (131) Xe ~ m and ~ (133) Xe ~ m was improved as compared with that of γ-ray only.