The novel properties of SF6 for directional dark matter experiments
The novel properties of SF6 for directional dark matter experiments
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SF6 用于定向暗物质实验的新特性
DOI：
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发表时间：
2016
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通讯作者：
E. Miller
中科院分区：
文献类型：
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作者：
N. Phan;R. Lafler;R. Lauer;E. Lee;D. Loomba;J. Matthews;E. Miller
SF6是一种惰性和电负性气体，在高压绝缘和许多其他工业应用中有着悠久的使用历史。尽管SF6被用作示踪成分以在跟踪室中引入稳定性，但其高度电负性限制了其在跟踪探测器中的使用。在这项工作中，我们提供了一系列的测量，以SF6为一次气体在一个低压时间投影室(TPC)，使用厚宝石作为雪崩和读出装置。给出了SF6中55Fe能谱的初步结果。迁移率和纵向扩散的测量证实了SF6的负离子漂移。然而，观测到的波形具有一种特殊而有趣的结构，表明存在多个漂移物种，并依赖于还原磁场(E/P)以及水蒸气污染程度。还介绍了在波形中发现明显的次峰，以及它的识别和在TPC中用于信任化事件。实验结果表明，SF6是定向暗物质探测的理想气体。特别是，高氟含量对于自旋相关的灵敏度是可取的，负离子漂移确保了大漂移距离上的低扩散，以及多种电荷载流子允许完全的探测器可信化。
SF6 is an inert and electronegative gas that has a long history of use in high voltage insulation and numerous other industrial applications. Although SF6 is used as a trace component to introduce stability in tracking chambers, its highly electronegative properties have limited its use in tracking detectors. In this work we present a series of measurements with SF6 as the primary gas in a low pressure Time Projection Chamber (TPC), with a thick GEM used as the avalanche and readout device. The first results of an 55Fe energy spectrum in SF6 are presented. Measurements of the mobility and longitudinal diffusion confirm the negative ion drift of SF6. However, the observed waveforms have a peculiar but interesting structure that indicates multiple drift species and a dependence on the reduced field (E/p), as well as on the level of water vapor contamination. The discovery of a distinct secondary peak in the waveform, together with its identification and use for fiducializing events in the TPC, are also presented. Our measurements demonstrate that SF6 is an ideal gas for directional dark matter detection. In particular, the high fluorine content is desirable for spin-dependent sensitivity, negative ion drift ensures low diffusion over large drift distances, and the multiple species of charge carriers allow for full detector fiducialization.