论文标题
测量探测器级硅用Snolab在damic的散装放射性污染
Measurement of the bulk radioactive contamination of detector-grade silicon with DAMIC at SNOLAB
论文作者
论文摘要
我们介绍了Snolab实验中damic的高抗性硅CCD中的散装放射性核糖计师的测量。我们利用CCD的精美空间分辨率来区分$α$和$β$衰减，并以高效率地搜索各种放射性同位素序列的空间相关衰减。使用与空间相关的$β$衰减，我们在CCD中测量$^{32} $ SI的大量放射性污染，$ 140 \ pm 30 $ $ $ $ $ $ $ $ bq/kg，并在bumk $^{210} $ pb的$ <160〜μ $ bq/kg上放置上限。使用对空间相关的批量$α$衰减的类似分析，我们将$ <11 $ $ $ $ $ $ $ bq/kg（0.9 ppt）设置为$^{238} $ u，$ <7.3 $ $ $ $ $ $ $ bq/kg（1.8 ppt）$^{232} $ th。 DAMIC CCD能够识别和拒绝空间上的背景，尤其是从$^{32} $ si中识别和拒绝对下一代基于硅的暗物质实验的重大影响，其中$β$从$^{32} $ si衰减中可能是主要背景。这种能力证明了CCD技术的准备就绪，以达到KG规模的暗物质敏感性。
We present measurements of bulk radiocontaminants in the high-resistivity silicon CCDs from the DAMIC at SNOLAB experiment. We utilize the exquisite spatial resolution of CCDs to discriminate between $α$ and $β$ decays, and to search with high efficiency for the spatially-correlated decays of various radioisotope sequences. Using spatially-correlated $β$ decays, we measure a bulk radioactive contamination of $^{32}$Si in the CCDs of $140 \pm 30$ $μ$Bq/kg, and place an upper limit on bulk $^{210}$Pb of $< 160~μ$Bq/kg. Using similar analyses of spatially-correlated bulk $α$ decays, we set limits of $< 11$ $μ$Bq/kg (0.9 ppt) on $^{238}$U and of $< 7.3$ $μ$Bq/kg (1.8 ppt) on $^{232}$Th. The ability of DAMIC CCDs to identify and reject spatially-coincident backgrounds, particularly from $^{32}$Si, has significant implications for the next generation of silicon-based dark matter experiments, where $β$'s from $^{32}$Si decay will likely be a dominant background. This capability demonstrates the readiness of the CCD technology to achieve kg-scale dark matter sensitivity.
