XENON10 Collaboration: Construction and Operation of a Liquid Xe Dark Matter Detector

XENON10 合作：液态 Xe 暗物质探测器的构建和操作

• 批准号: 0502690
• 负责人: Thomas Shutt
• 金额: --
• 依托单位: Case Western Reserve University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0502690&HistoricalAwards=false
• 关键词: XENON10; Collaboration; Construction; Operation; Liquid

The evidence is now overwhelming that ~ 25% of the mass-energy density of the universe is in the form of "dark matter". Discovering the nature of this dark matter is one of the most important questions in physics and cosmology. Perhaps the most compelling idea is that dark matter is composed of subatomic particles known as weakly interacting massive particles, or WIMPs, that were created in the big bang. They most likely have a mass roughly the same as an atom of gold, but are effectively incredibly small and difficult to detect. Such particles are a generic prediction of supersymmetry, the best-motivated theory for particle physics at higher energy scales than has been probed so far in accelerators. Probing for supersymmetry is one of the principle goals for the Large Hadron Collider at CERN. If WIMPs do exist, they must also be the dominant mass in our galaxy, and should be detectable from interactions in detectors on Earth. The rate of these interactions can be roughly predicted from the same physics that governs their production in the big bang, and is unfortunately small: somewhere between roughly 1 event/kg/month and 1 event/ton/year. Ambient backgrounds in particle detectors, both from radioactivity and cosmic rays, are much larger than this. Current searches have only just achieved sensitivity to the highest of these possible rates.The XENON collaboration has developed a new generation of dark matter detector based on liquid xenon. Like the current leading detectors, this technology has the ability to distinguish most radioactive backgrounds (gamma rays and betas), which cause an electron to recoil after the detector is struck, from WIMPs, which cause a nucleus to recoil. However it promises to more readily be scaled to the ton-scale needed to fully test the WIMP hypothesis than the current leading detectors, which have a mass of roughly 1 kg. The work funded here is participation in the XENON10, a ~10 kg prototype experiment which will be located in Gran Sasso, Italy. Our group is developing a system for removal of radioactive Kr which contaminates Xe, and is also developing a new method for removing other impurities that degrade the performance of the detector. Our group will also be involved in the design and construction of the detector, in particular wire grids used to measure ionization produced by WIMPs, and work on a CsI system for measuring scintillation. Finally, we will be involved in data taking operations and analysis.The nature of dark matter is one the most important questions in physics and cosmology, and is of great interest to the public at large. Our group will be actively engaged in public outreach, especially with local schools. Education and training of both undergraduate and graduate students is fundamental to this work, and students will have major roles in the proposed research. The technical aspects of experimental physics are a good foundation for a wide range of careers that benefit the public good. The specific techniques of very low background particle detection also have an important national security role in nuclear non-proliferation verification. Our group has been actively engaged in a joint effort between academic physicists and physicists in the defense non-proliferation community to develop advanced next-generation low radioactive background screening facilities. This work will indirectly benefit this effort.

现在有压倒性的证据表明，宇宙中大约25%的质能密度是以“暗物质”的形式存在的。 发现这种暗物质的性质是物理学和宇宙学中最重要的问题之一。 也许最令人信服的观点是，暗物质是由被称为弱相互作用大质量粒子（WIMP）的亚原子粒子组成的，这些粒子是在大爆炸中产生的。 它们很可能具有与金原子大致相同的质量，但实际上非常小，难以检测。 这样的粒子是超对称性的一般预测，超对称性是粒子物理学在更高能量尺度上的最佳动机理论，而不是迄今为止在加速器中探索的理论。 探测超对称性是欧洲核子研究中心大型强子对撞机的主要目标之一。如果WIMP确实存在，它们也必须是我们银河系中的主要质量，并且应该可以通过地球上的探测器的相互作用来检测。 这些相互作用的速率可以从大爆炸中控制它们产生的相同物理学中粗略预测，不幸的是很小：大约在1个事件/千克/月和1个事件/吨/年之间。 粒子探测器中来自放射性和宇宙射线的环境背景比这大得多。 目前的研究只是刚刚达到这些可能速率中最高的灵敏度。XENON合作开发了新一代基于液体氙的暗物质探测器。 与目前领先的探测器一样，这项技术能够区分大多数放射性背景（伽马射线和β射线），这些射线会在探测器被击中后导致电子反冲，而WIMP会导致原子核反冲。 然而，与目前质量约为1公斤的领先探测器相比，它更容易被缩放到完全测试WIMP假设所需的吨级。这里资助的工作是参与XENON 10，一个约10公斤的原型实验，将位于意大利的Gran Sasso。 我们的团队正在开发一种去除放射性氪的系统，这种氪会污染探测器，我们还在开发一种新的方法来去除其他会降低探测器性能的杂质。 我们的团队还将参与探测器的设计和建造，特别是用于测量WIMP产生的电离的线栅，并致力于测量闪烁的CsI系统。 暗物质的性质是物理学和宇宙学中最重要的问题之一，也是公众最感兴趣的问题之一。 我们的小组将积极参与公共宣传，特别是与当地学校。 本科生和研究生的教育和培训是这项工作的基础，学生将在拟议的研究中发挥重要作用。 实验物理学的技术方面是一个很好的基础，广泛的职业生涯，有利于公众利益。 极低本底粒子探测的具体技术在核不扩散核查中也具有重要的国家安全作用。 我们的小组一直积极参与学术物理学家和防扩散界物理学家之间的联合努力，以开发先进的下一代低放射性本底筛选设施。 这项工作将间接有助于这项工作。