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本工作利用~(140)Ce(n,2n)~(139m)Ce核反应,通过测量0.754MeV γ射线的强度测定了一些地质样品中铈的含量。所用仪器设备,样品制备方法请见前文。我们使用的照射时间、冷却时间和测量时间分别为120s、20s和120s。 由于地质样品中硅是普遍存在的,~(28)Si(n,p)~(28)Al反应所生成的核素~(28)Al会发射能量为1.78MeV的γ射线,它的双逃逸峰正好会干扰~(139m)Ce发射的能量为0.754MeV的γ射线的测量,因此,对于硅的干扰应加以校正。我们在实验中发现,100％的SiO_2生成的1.78MeV γ射线的双逃逸峰强度与1.73％的CeO_2生成的放射性强度相等,我们用此关系对SiO_2的干扰作了校正。另外,由于我们测定的几种样品中的钐、钕和
In this work, the cerium content of some geological samples was measured by measuring the intensity of 0.754 MeV γ-ray using ~ (140) Ce (n, 2n) ~ (139m) Ce nuclear reaction. Used equipment, sample preparation methods see above. We use the irradiation time, cooling time and measurement time were 120s, 20s and 120s. Due to the ubiquity of silicon in geological samples, the ~ (28) Al nuclei generated by ~ (28) Si (n, p) ~ (28) Al reaction emit γ-rays with energy of 1.78 MeV, The peak just interferes with the measurement of γ-rays with a energy of 0.754 MeV emitted by ~ (139m) Ce, so the interference with silicon should be corrected. We found in experiment that the double escape peak intensity of 1.78MeV γ-rays generated by 100% SiO_2 is equal to that of 1.73% CeO_2, and we use this relationship to correct the interference of SiO_2. In addition, due to the samarium, neodymium, and several of the samples we measured