Abstract COSINE-100 is a direct detection dark matter search experiment that uses a 106 kg array of eight NaI(Tl) crystals that are kept underground at the Yangyang Underground Laboratory to avoid cosmogenic activation of radioisotopes by cosmic rays. Even though the cosmogenic activity is declining with time, there are still significant background rates from the remnant nuclides. In this paper, we report measurements of cosmogenic isotope contaminations with less than one year half-lives that are based on extrapolations of the time dependent activities of their characteristic energy peaks to activity rates at the time the crystals were deployed underground. For longer-lived 109Cd ( T 1 / 2 = 1.27 y) and 22Na ( T 1 / 2 = 2.6 y), we investigate time correlations and coincidence events due to several emissions. The inferred sea-level production rates are compared with calculations based on the ACTIVIA and MENDL-2 model calculations and experimental data. The results from different approaches are in reasonable agreement with each other. For 3H, which has a long, 12.3 year half-life, we evaluated the activity levels and the exposure times that are in reasonable agreement with the time period estimated for each crystal’s exposure.

中文翻译：

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COSINE-100 NaI(Tl) 探测器中宇宙放射性核素的研究

摘要 COSINE-100 是一项直接探测暗物质搜索实验，它使用 106 kg 的 8 个 NaI(Tl) 晶体阵列，这些晶体被保存在阳阳地下实验室的地下，以避免宇宙射线对放射性同位素的宇宙成因激活。尽管宇宙活动随着时间的推移而下降，但仍然存在来自残余核素的显着背景率。在本文中，我们报告了半衰期不到一年的宇宙同位素污染的测量结果，这些测量结果是基于将晶体部署到地下时的特征能量峰值的时间相关活动与活动率的外推。对于寿命较长的 109Cd (T 1 / 2 = 1.27 y) 和 22Na (T 1 / 2 = 2.6 y)，我们研究了由于几种排放引起的时间相关性和巧合事件。将推断的海平面生产率与基于 ACTIVIA 和 MENDL-2 模型计算和实验数据的计算进行比较。不同方法的结果相互之间具有合理的一致性。对于半衰期长达 12.3 年的 3H，我们评估了活性水平和暴露时间，它们与每个晶体暴露的估计时间段合理一致。