14MeV中性子放射化分析法によるフッ素,酸素の非破壊同時定量

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タイトル別名
  • Simultaneous determination of fluorine and oxygen by nondestructive activation analysis with 14 MeV neutrons
  • 14MeV チュウセイシ ホウシャカ ブンセキホウ ニ ヨル フッソ , サンソ ノ ヒハカイ ドウジ テイリョウ ニジュウ ショウシャホウ ノ オウヨウ
  • Application of the double irradiation technique
  • 二重照射法の応用

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抄録

In the activation analysis of oxygen using, 16O (n, p) 16N reaction with 14 MeV neutrons the coexistence of fluorine in the sample seriously interferes with the oxygen analysis, owing to production of the same nuclides by 19F (n, α) 16N reaction. However, since there is a large difference between the threshold energies for the above-mentioned reactions (fluorine, 1.6 MeV; oxygen, 10.2 MeV), a double, irradiation technique provides a means to discriminate between 16N activities induced by both the reactions.<BR>As the result of application of the technique to 19F (n, α)16N-16O (n, p) 16N reaction system, the possibility of simultaneous determination of fluorine and oxygen was demonstrated. Analyses were made by means of 14 MeV neutrons produced by bombarding a tritium target with deuterons. In the double irradiation technique with 14 MeV neutrons, a neutron moderator is used in order to realize another irradiation position with different energy distribution. Fluorine and oxygen contents are evaluated by a mathematical treatment of the 16N specific activities of the analyzed samples and of the standard ones after the double irradiation with and without the neutron moderator. The use of a compound moderator in Fig. 6 which is composed of polyethylene and copper proved to be more effective to improve the analytical precision than a moderator that made of polyethylene only. The irradiation positions of samples and pneumatic transfer and detection systems in the double irradiation are shown in Fig. 1.<BR>As a preliminary experiment, synthetic samples prepared with sodium oxalate and sodium fluoride were analyzed, and the analytical results for the elements in those samples were in good agreement with the calculated values (Table II). Then, various samples such as other fluorides, slags and fluor spars were analyzed, and successful results were also obtained (Table III, IV).<BR>The analytical precision of the method depends especially on the mass ratio of fluorine to oxygen, mf /mo. The problem is discussed, based on the expected coefficient of variation as a function of the mf /mo ratio under various conditions (Fig. 8 and Table V). When the tolerable maximum coefficients of variation for the elements are 40, 20, 10 and 7.5% for the analytical levels of 50, 300, 700 and 1000mg, respectively, the application limits of the method are shown by curves 1 and 2 in Fig. 9.<BR>The method is useful in the determination of fluorine and/or oxygen above ca. 1% in materials which do not contain much boron impurities. Compared with the chemical analysis, it is rapid and nondestructive and one sample can be analyzed within 15 minutes in the case of 3 measurements. The double irradiation technique is very promising to avoide the mutual interference between fluorine and oxygen in neutron activation analysis.

収録刊行物

  • 分析化学

    分析化学 23 (1), 63-73, 1974

    公益社団法人 日本分析化学会

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