A Sensitive method for Sr-90 analysis by accelerator mass spectrometry

加速器質量分析によるSr-90の高感度法

笹 公和*; 本多 真紀   ; 細谷 青児*; 高橋 努*; 高野 健太*; 落合 悠太*; 坂口 綾*; 栗田 沙緒里*; 佐藤 志彦   ; 末木 啓介*

Sasa, Kimikazu*; Honda, Maki; Hosoya, Seiji*; Takahashi, Tsutomu*; Takano, Kenta*; Ochiai, Yuta*; Sakaguchi, Aya*; Kurita, Saori*; Satou, Yukihiko; Sueki, Keisuke*

Strontium-90 (Sr) is one of the most important fission products due to the potential health risks of its uptake and retention in the human body. Conventional analysis techniques involve beta-counting, which requires ingrowth of Y over a period of two weeks or more. Accelerator mass spectrometry (AMS) has the potential to shorten the analysis time while offering a lower limit of detection than beta-counting. Here, Sr in samples was recovered as SrF to provide sufficient negative ions in the caesium-sputtering ion source. In the sample preparation step, 95-98% of Sr was recovered and 99-100% of Zr removed by ion-exchange separation. Sr recovery was 30% in the precipitation process, and this can be improved. The recovered Sr was mixed with PbF at an SrF:PbF weight ratio of 4:1. A maximum 500 nA beam current of Sr ions was obtained from SrF samples. A five-anode gas ionization detector was used to avoid isobaric interference from Zr. The Sr/Sr atomic ratio background of 6 10 (equivalent to 3 mBq Sr) was comparable with that achieved at other AMS facilities. Good linearity Sr/Sr atomic ratios was obtained from 1.75 10 to 3.38 10. Suitable techniques for sample preparation and measurement were thus achieved for Sr analysis by AMS.