Grant: Subatomic Physics Envelope - Project

The SuperCDMS collaboration searches for dark matter particles with cryogenic germanium and silicon detectors. This technology's low energy threshold will give it world-leading sensitivity to light dark matter particles (between ~0.1-10 GeV/c2). The next phase of SuperCDMS is currently being installed at SNOLAB and will begin operations in 2023. Detectors operated with high bias voltages can convert ionization signals to amplified phonon signals using the Luke-Neganov effect, thus obtaining extremely good energy resolution and low thresholds. SuperCDMS SNOLAB's construction costs are jointly funded by CFI, the US DOE, and the US NSF. Canadian SuperCDMS collaborators play critical roles in the collaboration, leading the project's data acquisition and trigger effort, serving as analysis coordinator and Chair of the Collaboration Council, playing a leading role in computing and detector calibration, and pioneering several recent analyses. The Canadian group also developed and operates CUTE, an underground cryogenic test facility at SNOLAB that is being used for testing prototype SuperCDMS detectors and which serves as a general-purpose facility for cryogenic detector R&D requiring a deep underground location. SuperCDMS has made great strides in the last few years despite delays caused by the COVID-19 pandemic. The CUTE facility has been put into full operation, while substantial parts of SuperCDMS have been installed underground at SNOLAB. The complete detector payload has been constructed and is undergoing testing at SLAC, and will then be tested at CUTE early in 2023. The data acquisition system, a Canadian responsibility, was installed at SNOLAB last year. The final pieces of the experiment will be delivered in summer 2023, with commissioning beginning immediately afterwards. Data-taking will continue for approximately five years. The collaboration has published new results from photoneutron calibrations of ionization yield and searches for dark photons and axion-like particles, and has demonstrated impressive performance of new prototype detectors with resolution capable of resolving individual electron/hole pairs. These provide exciting upgrade paths for future detectors. The Canadian effort on SuperCDMS has grown quickly since our last NSERC renewal, with several new NSERC-eligible PIs joining this application. This coincides with the winding down of the McDonald Institute, and results in a significantly increased need for funds. This grant renewal requests support for students, postdoctoral fellows, conference and shift travel, and supplies for operations at SNOLAB and CUTE over the next three years, during which SuperCDMS will finish construction, complete its commissioning, and take its first science data. NSERC funds will leverage contributions from US partners to support SuperCDMS science and maintain Canada's leadership role as the host country of this world-leading experiment.