Design and construction of a new detector to measure ultra-low radioactive-isotope contamination of argon
Design and construction of a new detector to measure ultra-low radioactive-isotope contamination of argon
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DOI：
10.1088/1748-0221/15/02/p02024
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发表时间：
2020-02-01
影响因子：
1.3
通讯作者：
Zuzel, G.
中科院分区：
文献类型：
--
作者：
Aalseth, C. E.;Abdelhakim, S.;Zuzel, G.
大型液态氩探测器是通过星系中大质量弱相互作用粒子（WIMP）在原子核上的散射来探测它们的最佳途径之一。液氩靶允许通过闪烁信号的脉冲形状辨别来精确辨别核反冲信号和电子反冲信号。然而，大气中的氩（AAr）有一种天然存在的放射性同位素Ar-39，它是宇宙起源的β发射体。对于大型探测器来说，大气中的Ar-39活动引起了堆积问题。使用从地下威尔斯井中提取的氩气，剥夺了Ar-39，是这些实验的物理潜力的关键。DarkSide-20 k暗物质搜索实验将运行一个双相时间投影室，其中含有50吨放射性纯地下氩（UAr），该实验表明Ar-39相对于AAr的消耗系数大于1400。在提取过程中评估UAr的Ar-39含量对于DarkSide-20 k的成功以及全球氩暗物质合作组织（GADMC）的未来实验至关重要。这将由DArT在ArDM实验中进行，这是一个由极放射性纯材料制成的小腔室，将放置在西班牙Canfranc地下实验室（LSC）的ArDM探测器的中心。ArDM LAr体积充当背景放射性的主动否决，主要是来自ArDM探测器材料和周围岩石的伽马射线。本文介绍了ArDM项目中的DArT，包括腔室设计和构造，并回顾了实现探测器预期性能所需的背景。
Large liquid argon detectors offer one of the best avenues for the detection of galactic weakly interacting massive particles (WIMPs) via their scattering on atomic nuclei. The liquid argon target allows exquisite discrimination between nuclear and electron recoil signals via pulse-shape discrimination of the scintillation signals. Atmospheric argon (AAr), however, has a naturally occurring radioactive isotope, Ar-39, a beta emitter of cosmogenic origin. For large detectors, the atmospheric Ar-39 activity poses pile-up concerns. The use of argon extracted from underground wells, deprived of Ar-39, is key to the physics potential of these experiments. The DarkSide-20k dark matter search experiment will operate a dual-phase time projection chamber with 50 tonnes of radio-pure underground argon (UAr), that was shown to be depleted of Ar-39 with respect to AAr by a factor larger than 1400. Assessing the Ar-39 content of the UAr during extraction is crucial for the success of DarkSide-20k, as well as for future experiments of the Global Argon Dark Matter Collaboration (GADMC). This will be carried out by the DArT in ArDM experiment, a small chamber made with extremely radio-pure materials that will be placed at the centre of the ArDM detector, in the Canfranc Underground Laboratory (LSC) in Spain. The ArDM LAr volume acts as an active veto for background radioactivity, mostly gamma-rays from the ArDM detector materials and the surrounding rock. This article describes the DArT in ArDM project, including the chamber design and construction, and reviews the background required to achieve the expected performance of the detector.