RUI: A Search For Dark Matter With Superheated Liquid Targets

RUI：用过热液体目标寻找暗物质

• 批准号: 1506377
• 负责人: Ilan Levine
• 金额: $ 27.9万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506377&HistoricalAwards=false
• 关键词: RUI; Search; Dark; Matter; Superheated

One of the most enduring mysteries in science is the explanation for the evidence that, on all scales larger than a single star, far more gravitating material is seen to exist than can be accounted for by the atoms in these systems. This material, called Dark Matter (DM), is intrinsically invisible and has only conclusively been seen by its gravitational effects in aggregate. The objective of this project is to test the hypothesis that DM is an exotic particle, constituting about 85% of the mass of the Universe. If DM is observed in this detector, the project would be able to characterize basic properties such as its mass and the strength with which it interacts with ordinary matter.Many undergraduates have participated in the work at IUSB as have high school teachers and students. They have participated in all aspects of "big science" at an undergraduate institution. The group has aided the broader scientific community by fabricating specially designed transducers for a wide array of operating environments. An astrophysics experiment is now using acoustic particle ID in a bubble chamber to study exotic reactions relevant to large stars. The Muon Ionization Cooling Experiment uses them to understand electrical breakdown in RF cavities. A competing dark matter experiment uses them to eliminate boiling background. A neutron parity violation spin rotation experiment will use them to understand bubble migration in liquid helium.This award provides funds to enable the IUSB group to continue to contribute to the detector R&D, installation, commissioning and running of the PICO bubble chambers and analysis of the resulting data. PICO uses superheated liquids to search for the tiny energy depositions left by nuclei recoiling due to collisions with dark matter. These depositions cause the liquid to explosively transform into gas. The bubble chamber technique represents a unique approach in the field, since it is inherently immune to sparsely ionizing particles (such as electrons), which are serious backgrounds to other DM detectors. This will be especially important if robust observation claims are made by experiments in the future. It has also been demonstrated by the group that the target fluids are easily changed, which will be important in determining the properties of any observed DM particle. The IUSB group has designed and fabricated all of the acoustic transducers for the detectors. The group recently discovered that one can even distinguish what kind of nucleus has decayed. IUSB also participates in the commissioning and running of the various bubble chambers at the deep site and energy threshold experiments at the Fermilab test-beam facility. A new design for transducers mounted in the dome over the bellows system will be made for a ton-scale detector. The group will also continue to contribute to the analysis of data already collected with the COUPP-60 and PICO-2L detectors.

科学上最持久的谜团之一是对证据的解释，即在比单个星星更大的所有尺度上，存在的引力物质远远超过这些系统中原子所能解释的。这种物质被称为暗物质（DM），本质上是不可见的，只有通过其聚集的引力效应才能最终被看到。该项目的目的是检验DM是一种奇异粒子的假设，占宇宙质量的85%左右。如果在这个探测器中观测到DM，该项目将能够表征其基本性质，如其质量和与普通物质相互作用的强度。许多大学生和高中教师和学生都参加了IUSB的工作。他们在本科院校参与了“大科学”的各个方面。该小组通过为各种操作环境制造专门设计的传感器来帮助更广泛的科学界。一项天体物理学实验正在气泡室中使用声学粒子ID来研究与大型恒星相关的奇异反应。μ子电离冷却实验使用它们来理解射频腔中的电击穿。一个与之竞争的暗物质实验使用它们来消除沸腾的背景。一个中子宇称破坏自旋旋转实验将使用它们来了解液氦中的气泡迁移。该奖项提供资金，使IUSB小组能够继续为皮科气泡室的探测器研发，安装，调试和运行以及分析结果数据做出贡献。皮科使用过热的液体来寻找由于与暗物质碰撞而反冲的原子核留下的微小能量沉积。这些沉积物导致液体爆炸性地转化为气体。气泡室技术代表了该领域中的一种独特方法，因为它固有地不受稀疏电离粒子（例如电子）的影响，而这些粒子对其他DM探测器来说是严重的背景。如果将来通过实验提出强有力的观测声明，这将特别重要。该小组还证明，目标流体很容易改变，这对于确定任何观察到的DM颗粒的性质都很重要。IUSB小组设计并制造了探测器的所有声换能器。该小组最近发现，人们甚至可以区分出哪种原子核已经衰变。国际宇宙学联合会还参与了深层站点各种气泡室的调试和运行以及费米实验室试验束设施的能量阈值实验。将为吨级探测器设计一种新的传感器，安装在波纹管系统上方的圆顶中。该小组还将继续协助分析COUPP-60和皮科-2L探测器已经收集的数据。