RUI: A Search For Dark Matter With Superheated Liquid Targets

科学界最经久不衰的谜团之一是对以下证据的解释：在所有比一颗恒星更大的尺度上，存在的引力物质远远超过这些系统中的原子所能解释的数量。这种物质被称为暗物质(DM)，本质上是看不见的，只有通过它的引力效应才能最终看到。这个项目的目标是检验Dm是一种奇异粒子的假设，它约占宇宙质量的85%。如果在这个探测器上观察到DM，该项目将能够表征它的基本性质，如它的质量和它与普通物质相互作用的强度。许多本科生和高中老师和学生都参与了IUSB的工作。他们在一所本科院校参加了各个方面的“大科学”。该小组通过为广泛的操作环境制造专门设计的换能器，帮助了更广泛的科学界。一项天体物理实验现在正在使用气泡室中的声粒子ID来研究与大型恒星相关的奇异反应。Muon电离冷却实验使用它们来了解射频腔中的电击穿。一个相互竞争的暗物质实验使用它们来消除沸腾的背景。中子宇称破坏自旋旋转实验将利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、调试和运行以及对结果数据的分析做出贡献。Pico使用过热的液体来寻找由于与暗物质碰撞而导致的原子核反冲留下的微小能量沉积。这些沉积会导致液体爆炸性地转化为气体。气泡室技术代表了该领域的一种独特方法，因为它固有地不受稀疏电离粒子(如电子)的影响，而稀疏电离粒子是其他DM探测器的严重背景。如果未来通过实验得出可靠的观测结论，这一点将尤为重要。该小组还证明，目标流体很容易改变，这对确定任何观察到的DM颗粒的性质将是重要的。IUSB小组已经设计和制造了探测器的所有声学换能器。该研究小组最近发现，人们甚至可以分辨出哪种核已经衰变。IUSB还参与了深部各种气泡室的调试和运行，以及费米拉试验束设施的能量阈值实验。将为吨级探测器制造安装在波纹管系统上方的穹顶内的传感器的新设计。该小组还将继续协助分析已经用COUPP-60和Pico-2L探测器收集的数据。

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.