Evaluation and mitigation of trace 210Pb contamination on copper surfaces
Evaluation and mitigation of trace 210Pb contamination on copper surfaces
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DOI：
10.1016/j.nima.2020.163870
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
R. Bunker;T. Aramaki;I. Arnquist;R. Calkins;J. Cooley;E. Hoppe;J. Orrell;K. Thommasson
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文献类型：
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作者：
R. Bunker;T. Aramaki;I. Arnquist;R. Calkins;J. Cooley;E. Hoppe;J. Orrell;K. Thommasson
许多低本底物理实验需要清洁的材料来构建和操作。高纯度铜由于其物理性质和可用性而得到广泛应用。在本文中，我们描述的方法来测定和减轻210铅污染的铜表面，如暴露于环境氡或来自散装杂质。我们评估了湿法蚀刻对商业样品的功效，并观察到来自铜块体的210 Po污染不容易进入溶液。在蚀刻期间，钋似乎捕获在铜-蚀刻剂边界处，使得其有效地集中在铜表面处。我们观察到210 Pb的不同行为;高灵敏度的α发射率随时间的变化测量表明，商业铜表面有史以来报告的210 Pb污染水平最低：0 ± 12 nBq/cm 2（1 σ）。此外，我们已经证明了使用定制的高纯度电镀技术减轻痕量210 Pb和210 Po表面背景的有效性。利用XIA UltraLo-1800 α光谱仪进行的测定对这些方法进行了评价。
Clean materials are required to construct and operate many low-background physics experiments. High-purity copper has found broad use because of its physical properties and availability. In this paper, we describe methods to assay and mitigate 210 Pb contamination on copper surfaces, such as from exposure to environmental radon or coming from bulk impurities. We evaluated the efficacy of wet etching on commercial samples and observed that 210 Po contamination from the copper bulk does not readily pass into solution. During the etch, the polonium appears to trap at the copper–etchant boundary, such that it is effectively concentrated at the copper surface. We observed a different behavior for 210 Pb; high-sensitivity measurements of the alpha emissivity versus time indicate the lowest level of 210 Pb contamination ever reported for a commercial copper surface: 0±12 nBq/cm 2 (1 σ). Additionally, we have demonstrated the effectiveness of mitigating trace 210 Pb and 210 Po surface backgrounds using custom, high-purity electroplating techniques. These approaches were evaluated utilizing assays performed with an XIA UltraLo-1800 alpha spectrometer.