SuperCDMS SNOLAB: Calibration, Commissioning, and Beyond

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Multiple astronomical observations have established that about 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. Deciphering the nature of this so-called 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 to help reject backgrounds due to cosmic rays. 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 constituent of the Universe and of physics beyond the Standard Model of particle physics. This award will support students and scientists working on the SuperCDMS SNOLAB experiment that aims to achieve world-leading sensitivity for dark matter searches in the 1-10 GeV/c2 mass range.The SuperCDMS SNOLAB experiment will have a broad impact which extends beyond the search for dark matter. The experimental and R&D efforts further advance phonon-mediated detectors and new active veto concepts, which can have applications in cosmology, astronomy and industry. This effort will contribute to the training of undergraduate and graduate students and postdoctoral researchers, continuing the group?s strong involvement in mentoring undergraduates from underrepresented groups by participating in the Summer Research Opportunities Program (SROP), which brings undergraduates from across the U.S. to do a summer of research at Northwestern. This award has the following objectives: (1) to measure a dark matter signal or place world-leading limits for the WIMP-nucleon cross section at masses below 10 GeV/c2 by analyzing the electron-recoiling dark matter candidates from the existing SuperCDMS Soudan data; (2) to performance test the first production SuperCDMS SNOLAB detectors at the CUTE test facility in SNOLAB; and (3) to play a central role in the pre-operations and commissioning of the SuperCDMS SNOLAB experiment. This award will focus on the calibration of the nuclear energy scale, which is a measurement which is essential to obtain science from SuperCDMS SNOLAB. The nuclear energy scale will be measured in a dedicated testing campaign using both high resolution ionization yield measurements using small R&D detectors at the Triangle Universities Nuclear Laboratory (TUNL) neutron beam facility, and full-size SuperCDMS SNOLAB detectors at the new NEXUS (Northwestern Experimental Underground Site) at Fermilab.