Application of triple coincidence in prompt -ray analysis and neutron activation analysis

三重線同時計数法の即発線分析及び中性子放射化分析への適用

大島 真澄; 藤 暢輔   ; 村上 幸弘*; 初川 雄一; 金 政浩; 木村 敦   ; 中村 詔司  ; 小泉 光生 ; 古高 和禎  

Oshima, Masumi; Toh, Yosuke; Murakami, Yukihiro*; Hatsukawa, Yuichi; Kin, Tadahiro; Kimura, Atsushi; Nakamura, Shoji; Koizumi, Mitsuo; Furutaka, Kazuyoshi

当グループにおいては核データ測定の応用研究として、即発線分析及び中性子放射化分析による微量元素分析法の開発研究を実施している。これまでは2重線同時計数で得られる2次元マトリクス解析により、高感度分析を実証した。今回、新たに3重同時計数法を適用することによる定量限界の改善を試みた。現状のJRR-3に設置された多重即発線分析装置による測定・解析の結果、S/N比は改善するものの、統計ロスによる効果により、3次元法での定量限界は2次元法とほぼ同等になるという結論を得た。今後STELLA装置の高効率化,バックグラウンド除去により、高感度化を図る。

Prompt -ray analysis (PGA) is a versatile element quantification method with non-destructive, rapid, high-precision and multi-element determination. In actual application, however, the energy resolution of commercial Ge detectors is not sufficient and it is impossible to resolve all the -rays, since the number of -rays from the sample with multiple elements often exceeds one thousand. In a similar situation in Neutron Activation Analysis (NAA), we have applied a -ray coincidence method (multiple -ray detection method), and developed a new method of NAA coupled with Multiple -ray detection (NAAMG). Its high sensitivity is demonstrated in nuclide quantification. We apply the multiple -ray detection method to prompt -ray analysis (Multiple Prompt -ray Analysis, MPGA) by using a new -ray detector array at a cold neutron beam line in Japan Research Reactor, JRR-3, at Japan Atomic Energy Agency (JAEA). In MPGA analysis we have used so far the -ray double coincidence measurement. We firstly try to apply a triple coincidence measurement. The present detector system can afford the double and triple coincidence measurement as well as the singles measurement in PGA and NAA. In the presentation we compare the detection limits for those measurements. Based on the results we demonstrated that the triple coincidence is effective in some applications such as Ir concentration in rock samples. We also discuss results of applications to environmental samples.