DUSEL R&D: Depleted Argon from Underground Sources

杜塞尔R

• 批准号: 0811186
• 负责人: Cristiano Galbiati
• 金额: $ 166.68万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0811186&HistoricalAwards=false
• 关键词: DUSEL; R& Depleted; Argon; Underground

Evidence for the existence of dark matter is now compelling, but its nature remains a fundamental mystery. Particularly intriguing is the possibility that dark matter is made of Weakly Interacting Massive Particles. These may be detected by their collisions with nuclei, but the expected low rate of such collisions and low energy of the recoil nuclei require massive detectors with extremely low background rates. Liquid argon is an excellent target for scintillation and ionization detectors and has unique features that make it particularly attractive for the detection of dark matter. Possible limits to size and sensitivity of argon dark matter detectors come from Argon-39, a radioactive product of cosmic rays that pollutes atmospheric argon at the level of one Becquerel/kilogram. Argon depleted in Argon-39 would be highly desirable to improve the sensitivity of the current detectors and to permit construction of future multi-ton argon dark matter detectors. Centrifugation and differential thermal diffusion are established techniques for Argon-39/Argon-40 isotopic separation, but, with their cost and the global production capacity, these options are not practical. Natural gas wells are a promising source because Argon-39 production by cosmic rays is strongly suppressed underground. The PIs are conducting an investigation of the Argon-39/Argon-40 ratio in underground wells and have so far identified two sources of gas containing argon depleted in Argon-39. This award provides funding to deploy a small-scale system to collect and purify argon with a production rate of about 1 kilogram/day. In addition, this award will be used to develop a low-background 1-kilogram liquid argon detector with a sensitivity to Argon-39 that is 0.1% of the level in atmospheric argon. It will be used to monitor the production of the underground argon gas and to test 1-kilogram gas samples from other gas sources, should they become available. For Broader Impacts, this work will advance the education of graduate and undergraduate students. Depleted argon may also enable studies on neutrinos from reactors and from high-intensity stopped-pion neutrino sources, and the development of very sensitive neutron detectors.

暗物质存在的证据现已令人信服，但其本质仍然是一个基本谜团。特别有趣的是暗物质可能是由弱相互作用的大质量粒子组成的。这些可以通过它们与原子核的碰撞来检测到，但是预期的此类碰撞的低发生率和反冲核的低能量需要具有极低背景率的大型探测器。液氩是闪烁和电离探测器的绝佳目标，并且具有独特的功能，使其对于暗物质的探测特别有吸引力。氩暗物质探测器的尺寸和灵敏度可能受到 Argon-39 的限制，Argon-39 是一种宇宙射线的放射性产物，对大气中的氩的污染程度为 1 贝克勒尔/千克。 Argon-39 中的贫氩对于提高当前探测器的灵敏度并允许建造未来的数吨级氩暗物质探测器是非常理想的。离心和差热扩散是用于 Argon-39/Argon-40 同位素分离的成熟技术，但考虑到其成本和全球生产能力，这些选择并不实用。天然气井是一个很有前途的来源，因为宇宙射线产生的 Argon-39 在地下受到强烈抑制。 PI 正在对地下井中的 Argon-39/Argon-40 比率进行调查，迄今为止已确定了两个含有 Argon-39 中贫氩的气体来源。该奖项提供资金来部署一个小型系统来收集和纯化氩气，生产率约为每天 1 公斤。此外，该奖项还将用于开发低本底1公斤液氩探测器，其对Argon-39的灵敏度仅为大气中氩水平的0.1%。它将用于监测地下氩气的生产，并测试来自其他气源的 1 公斤气体样品（如果有）。为了产生更广泛的影响，这项工作将促进研究生和本科生的教育。贫氩还可以用于研究来自反应堆和高强度停电中微子源的中微子，以及开发非常灵敏的中子探测器。