DUSEL R&D: Detection of impurities in cryogenic liquids with extreme sensitivity

杜塞尔R

• 批准号: 0810495
• 负责人: Carter Hall
• 金额: $ 31.42万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-15 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0810495&HistoricalAwards=false
• 关键词: DUSEL; R& Detection; impurities; cryogenic

Recent years have seen a proliferation of experiments based on the liquid noble gas detector technology. Noble gases are an attractive medium for particle detectors due to their low ionization potential, high scintillation efficiency, long electron lifetime and low cost. These detectors are currently employed to address a wide variety of fundamental physics questions, including neutrinoless double beta decay, neutrino oscillations, rare muon decays, dark matter searches and solar neutrinos. Many of these questions are central to the scientific mission of an underground lab and similar detectors have been proposed for the initial suite of experiments at DUSEL. Most liquid detectors to date are of relatively modest size, with target masses ranging from a few kilograms to a few hundred kilograms. However, next-generation experiments are poised to push the boundaries far beyond the current state of the art. For an experiment to succeed in this new regime, it will be necessary to purify the cryogenic liquids far beyond what current technologies have achieved. For existing TPC-style detectors, the concentration of electronegative impurities must be less than about 100 ppt oxygen equivalent to avoid attenuation of the charge signal as it drifts through the detector volume. Therefore, the next set of experiments will require impurity concentrations from one to ten ppt, or free electron lifetimes from tens to hundreds of milliseconds. This award will enable the group to develop a new method for detecting extremely low concentrations of impurities, with the potential to extend current sensitivities by several orders of magnitude. As part of the Broader Impacts of this work, this impurity detector would find wide application for many of the fundamental physics experiments which are likely to be hosted by DUSEL. In addition, this work will also have significantly broader impact by serving to further the education of graduate students.

近年来，基于液态惰性气体探测技术的实验激增。惰性气体具有电离势低、闪烁效率高、电子寿命长、成本低等优点，是粒子探测器的理想介质。这些探测器目前被用于解决各种各样的基础物理问题，包括中微子双β衰变、中微子振荡、罕见的μ子衰变、暗物质搜索和太阳中微子。这些问题中的许多都是地下实验室科学任务的核心，类似的探测器已经被提议用于DUSEL的初始实验套件。迄今为止，大多数液体探测器的体积相对较小，目标质量从几公斤到几百公斤不等。然而，下一代实验已经准备好超越目前的技术水平。为了在这种新体制下取得实验成功，有必要对低温液体进行远远超出当前技术所能达到的纯化。对于现有的tpc型探测器，电负性杂质的浓度必须小于约100 ppt氧当量，以避免电荷信号在探测器体积中漂移时的衰减。因此，下一组实验将需要杂质浓度从1到10ppt，或者自由电子寿命从几十到几百毫秒。该奖项将使该小组能够开发一种检测极低浓度杂质的新方法，并有可能将电流灵敏度提高几个数量级。作为这项工作更广泛影响的一部分，这种杂质探测器将广泛应用于许多可能由DUSEL主持的基础物理实验。此外，这项工作还将对研究生的进一步教育产生更广泛的影响。