Abstract Thermal Ionization Mass Spectrometry (TIMS) has been evaluated for the detection of the radioactive isotopes of Sr and Cs. The commercial instrument (i.e., a Thermo Scientific Triton) was investigated for the analysis of isotopic ratios of 89Sr/90Sr and 135Cs/137Cs in the presence of atomic isobars (89Y and 90Zr for 89,90Sr analysis and 135,137Ba for 135,137Cs analysis). The decontamination achievable instrumentally was examined by isotopic ratio measurements of 89Y/88Sr and 90Zr/88Sr for Sr and 135Ba/133Cs and 137Ba/133Cs for Cs. The decontamination found was at or above 2.0E+8 for 90Zr from 88Sr, while the Y demonstrated a temperature dependence as it sublimed from the filament but remained better than ≈ 5E+7. The decontamination of Ba from Cs did not show any temperature dependence and remained above 5E+6 and 8E+6 for 135Ba and 137Ba from 133Cs, respectively. Two standard fusion procedures one with sodium hydroxide (NaOH) plus sodium peroxide (Na2O2) flux, and the second used lithium tetraborate (Li2B4O7) plus lithium metaborate (LiBO2) flux were evaluated for preparation of sample matrices prior to performing chemical separations. Ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) and Sr-spec resin were used to isolate the Cs and Sr, respectively from a prepared background matrix (i.e., Montana Soil). A graded approach, increasing in stable background isotopes, was performed to monitor the chemical and instrumental response. The radioisotopes of Sr and Cs were produced by thermal neutron irradiation of a highly enriched uranium foil. Even though the irradiated sample was not a certified standard it does provide accurate expectation values via the published cumulative fission yield nuclear data in the Evaluated Nuclear Data Files (ENDF) [ 1 ]. The intra-element isotopic ratio results presented in this work for 89Sr/90Sr and 135Cs/137Cs agree with the published data at 1σ. Furthermore, the uncertainty of the isotopic ratio measurements with TIMS was a factor of 5–10 improved compared to these published values.

中文翻译：

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用热电离质谱法分析测定放射性锶和铯

摘要 热电离质谱 (TIMS) 已被评估用于检测 Sr 和 Cs 的放射性同位素。研究了商业仪器（即 Thermo Scientific Triton）在原子等压线存在下分析 89Sr/90Sr 和 135Cs/137Cs 的同位素比（89Y 和 90Zr 用于 89,90Sr 分析，135,137Ba 用于 135,137Cs 分析） . 通过对 Sr 的 89Y/88Sr 和 90Zr/88Sr 以及 Cs 的 135Ba/133Cs 和 137Ba/133Cs 的同位素比测量，可以用仪器检查可实现的净化。对于来自 88Sr 的 90Zr，发现的去污率等于或高于 2.0E+8，而 Y 在从灯丝升华时表现出温度依赖性，但仍优于 ≈ 5E+7。来自 Cs 的 Ba 的净化没有表现出任何温度依赖性，并且对于来自 133Cs 的 135Ba 和 137Ba 分别保持在 5E+6 和 8E+6 以上。在执行化学分离之前，评估了两种标准融合程序，一种是使用氢氧化钠 (NaOH) 加过氧化钠 (Na2O2) 助熔剂，另一种是使用四硼酸锂 (Li2B4O7) 加偏硼酸锂 (LiBO2) 助熔剂，以制备样品基质。使用钼磷酸铵-聚丙烯腈 (AMP-PAN) 和 Sr-spec 树脂分别从制备的背景基质（即蒙大拿州土壤）中分离 Cs 和 Sr。执行分级方法，增加稳定背景同位素，以监测化学和仪器响应。Sr 和 Cs 的放射性同位素是通过高浓缩铀箔的热中子辐射产生的。尽管辐照样品不是经过认证的标准，但它确实通过评估核数据文件 (ENDF) [1] 中公布的累积裂变产额核数据提供了准确的预期值。在这项工作中提出的 89Sr/90Sr 和 135Cs/137Cs 的元素内同位素比结果与 1σ 的公布数据一致。此外，与这些公布的值相比，TIMS 同位素比测量的不确定性提高了 5-10 倍。