R&D toward SuperCDMS at SNOLAB

对星系、超星系团、遥远的超新星和宇宙微波背景辐射的观测告诉我们，宇宙中约85%的物质不是由已知粒子组成的。破译这种暗物质的本质对宇宙学、天体物理学和高能粒子物理学具有重要意义。一个主要的假设是，它是由相互作用很弱的大质量粒子组成的，这些粒子是在大爆炸后不久产生的。如果WIMP是暗物质，那么它们在我们银河系中的存在可能是通过位于地下深处的探测器中原子核的散射来检测到的。低温暗物质搜索(CDMS)合作开创了使用低温声子介导的探测器来探测WIMP在原子核上罕见的散射并将它们与背景区分开来的先河。CDMS目前在明尼苏达州的苏丹市运行，配备了10公斤的iZip探测器，这些探测器已经证明，对于数百公斤的目标，背景抑制系数足以进行零背景操作。为了充分利用这一能力，有必要建立一个新的更大、更清洁的实验装置，并将其放置在比南丹更深的位置，以消除宇宙成因的中子本底。这项新实验的基线设计(SuperCDMS SNOLAB)要求在加拿大萨德伯里的SNOLAB进行一个100公斤的锗实验，将iZip技术应用于直径100毫米、质量为1.4公斤的探测器。该奖项为该实验的研究和开发提供了支持。它侧重于关键的研发目标：拟议探测器的测试和表征，对冷硬件和电子设备(用于电离和声子读出的新型HEMT和SQUID)的设计和测试的贡献，以及锗晶体的采购和表征。更广泛的影响：SuperCDMS实验将产生超越暗物质搜索的广泛影响。这项技术的发展将进一步推动声子介导的探测器的发展，这种探测器已经在宇宙学、天文学和工业中得到了许多应用。该项目将有助于培训本科生和研究生以及博士后研究人员，使用测量技术的前沿技术。SuperCDMS的科学家将继续参与K-12，他们与教师的合作，以及他们对来自贫困背景的有前途的高中生的支持。

Observations of galaxies, superclusters, distant supernovae, and the cosmic microwave background radiation tell us that ~85% of the matter in the universe is not made of known particles. Deciphering the nature of this dark matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. A leading hypothesis is that it is comprised of Weakly Interacting Massive Particles, or WIMPs, that were produced moments after the Big Bang. If WIMPs are the dark matter, then their presence in our galaxy may be detectable via scattering from atomic nuclei in detectors located deep underground.The Cryogenic Dark Matter Search (CDMS) Collaboration has pioneered the use of low temperature phonon-mediated detectors to detect the rare scattering of WIMPs on nuclei and distinguish them from backgrounds. CDMS is currently operating at Soudan, Minnesota with 10 kg of iZIP detectors, which have already demonstrated a background rejection factor sufficient for zero background operation with several hundred kilogram targets. In order to fully use this capability, it is necessary to build a new larger and cleaner experimental set up and locate it at a much deeper site than Soudan to eliminate the cosmogenic neutron background. The baseline design of this new experiment (SuperCDMS SNOLAB) calls for a 100 kg germanium experiment located at SNOLAB, Sudbury, Canada adapting the iZIP technology to 100 mm diameter detectors of 1.4 kg mass each.This award provides support for Research and Development towards this experiment. It focuses on critical R&D goals: the testing and characterization of the proposed detectors, contribution to the design and testing of the cold hardware and electronics (novel HEMT and SQUID for ionization and phonon readout), and the procurement and characterization of the germanium crystals. Broader impacts: The SuperCDMS experiment will have a broad impact which extends beyond the dark matter search. The technical development will further advance phonon-mediated detectors, which have already found many applications in cosmology, astronomy and industry. The project will contribute to the training of undergraduate and graduate students and postdoctoral researchers, using techniques at the leading edge of measurement technologies. SuperCDMS scientists will continue their involvement in K-12, their collaboration with teachers and their support for promising high school students from underserved backgrounds.