Collaborative Research: The SuperCDMS SNOLAB Experiment

观测表明，宇宙中85%的物质不是由正常原子组成的，而是不会发射或吸收光线的、未被探测到的基本“暗物质”粒子。值得注意的是，出于其他原因提出的粒子物理理论预测，存在具有合适性质的弱相互作用大质量粒子(WIMP)，正是这种暗物质。如果WIMP是暗物质，那么当它们在地球上的探测器中散射时，它们可能是可以探测到的。WIMP暗物质的直接探测将解开粒子物理学和宇宙学中的一个基本谜团，为了解宇宙的初级物质组成和超越粒子物理标准模型的物理学提供了一个独特的窗口。在过去的三年里，SuperCDMS的合作在寻找低质量暗物质方面处于领先地位。CDMSlite的最新结果达到了电子反冲的能量阈值，低至56 eV。这些结果排除了暗物质-核子自旋独立截面的新参数空间，暗物质质量在1.6到5.5GeV/c2之间。该项目将专注于更好地了解信号探测器的反应，以推动超级CDMS变得更加灵敏。SuperCDMS SNOLAB实验将产生广泛的影响，超越了对暗物质的搜索。该实验的声子介导的探测器在宇宙学、天文学和工业中都有应用。这一努力将为培养本科生和研究生以及博士后研究人员提供机会。SuperCDMS将参与当地机构的教育和外联活动，并将协调SNOLAB和南达科他州桑福德地下研究设施(SURF)的外联活动，以扩大更广泛的影响，重点是中等教育。该奖项将支持参加SNOLAB主办的教师研讨会，为美国教育工作者修改和提供中学暗物质教育模块，并为SNOLAB和SURF维护与SuperCDMS相关的外展材料。现有的联盟将使接触萨德伯里第一民族社区成为可能。这项工作还将支持研究生教育和对代表性不足群体的推广。为了最大限度地提高超级CDMS SNOLAB的科学产出，需要详细了解探测器对潜在信号和背景的反应。在两个地下设施(费米拉实验室的Nexus和SNOLAB的CATE)的测量将表征和校准生产前的SuperCDMS SNOLAB探测器和第一个生产的SuperCDMS SNOLAB塔，并在大学测试设施的小型设备上进行辅助测量。由此产生的数据将有助于进行能级校准、背景水平的测量、了解探测器的详细声子和电子物理、开发改进的背景抑制技术、验证和调整探测器蒙特卡罗以及优化SuperCDMS SNOLAB的操作参数。这些数据还应该提供具有世界领先灵敏度的暗物质搜索。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Observations indicate that 85% of the matter in the Universe is not made of normal atoms but must be otherwise undetected elementary "dark matter" particles that do not emit or absorb light. Remarkably, particle physics theories proposed for other reasons predict the existence of Weakly Interacting Massive Particles (WIMPs) with just the right properties to be this dark matter. If WIMPs are the dark matter, they may be detectable when they scatter in Earth-based detectors. Direct detection of WIMP dark matter would solve a fundamental mystery in particle physics and cosmology, providing a unique window to learning about the primary matter constituents of the Universe and of physics beyond the Standard Model of particle physics. Over the past three years, the SuperCDMS collaboration has led the field in the search for low-mass dark matter. The most recent results from CDMSlite reached an energy threshold for electron recoils as low as 56 eV. These results excluded new parameter space for the dark matter-nucleon spin-independent cross section for dark matter masses between 1.6 and 5.5 GeV/c2. This project will focus on better understanding the response of the signal detectors in a push to make the SuperCDMS yet more sensitive.The SuperCDMS SNOLAB experiment will have a broad impact which extends beyond the search for dark matter. The experiment's phonon-mediated detectors have applications in cosmology, astronomy and industry. This effort will contribute opportunities for training of undergraduate and graduate students and postdoctoral researchers. SuperCDMS will engage in education and outreach at local institutions and will coordinate outreach at SNOLAB and the Sanford Underground Research Facility (SURF) in South Dakota to increase the broader impact with a focus on secondary education. This award will support participating in SNOLAB-hosted teacher workshops, modifying and providing middle school dark matter education modules to U.S. educators, and maintaining SuperCDMS-related outreach materials for SNOLAB in Canada and SURF. Existing alliances will enable out-reach to Sudbury First Nations communities. This effort will also support post-graduate education and outreach to underrepresented groups.In order to maximize the science output of SuperCDMS SNOLAB, detailed understanding of the response of detectors to potential signals and backgrounds is required. Measurements at two underground facilities (NEXUS at Fermilab and CUTE at SNOLAB) will characterize and calibrate pre-production SuperCDMS SNOLAB detectors and the first production SuperCDMS SNOLAB towers, with supporting measurements from small devices at university test facilities. Resulting data will allow energy scale calibration, measurements of background levels, understanding of the detailed phonon and electron physics of the detectors, development of improved background-rejection techniques, validation and tuning of Detector Monte Carlo, and optimization of SuperCDMS SNOLAB operational parameters. These data should also provide a dark matter search with world-leading sensitivity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.