SuperCDMS Reaches Near Absolute Zero in Dark Matter Search

Deep beneath the Earth’s surface, the Super Cryogenic Dark Matter Search (SuperCDMS) has achieved a significant milestone by reaching operating temperatures just a few thousandths of a degree above absolute zero. Located at SNOLAB, approximately 6,800 feet underground in a nickel mine near Sudbury, Ontario, this facility provides an environment shielded from cosmic rays and other background particles that could interfere with the detection of dark matter. This achievement marks the transition from years of construction to the commencement of scientific operations, allowing the detectors to activate and begin their search for dark matter particles.

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Dark matter constitutes about 85 percent of all matter in the universe, yet it has never been directly observed. Its existence is inferred from gravitational effects on galaxies, but its true nature remains elusive. The SuperCDMS experiment is designed to detect dark matter particles by capturing rare interactions with ordinary matter as they pass through Earth. Priscilla Cushman, a professor at the University of Minnesota and spokesperson for SuperCDMS, emphasized the importance of reaching base temperature, stating, “At these extremely low temperatures, our installed detectors can now scan a whole new region of parameter space where the lightest dark matter particles may be lurking.”

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The University of Minnesota team has developed a sophisticated shielding system to protect the detectors from trace radiation and neutrons generated by cosmic rays interacting with the cavern walls. This cylindrical enclosure, measuring four meters in height and diameter, is constructed with layers of ultra-pure lead to block gamma radiation and high-density polyethylene to reduce neutron activity. In addition to the installation and cooling of the experiment, the team has created advanced reconstruction algorithms and analysis methods to identify potential dark matter signals as data collection begins.

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With the base temperature achieved, the next phase involves detector commissioning, which will take several months to activate, calibrate, and fine-tune each detector channel. Beyond the search for dark matter, SuperCDMS will also facilitate the study of rare isotopes, explore previously unmeasured energy ranges, and potentially uncover new types of particle interactions. The project is a collaborative effort supported by the U.S. Department of Energy Office of Science, the U.S. National Science Foundation, the Canada Foundation for Innovation, and the Natural Sciences and Engineering Research Council of Canada. The University of Minnesota team includes various researchers and graduate students dedicated to advancing this critical area of physics.

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• “Getting to base temperature is a major milestone in a years-long campaign to build a low-background facility capable of housing our sensitive cryogenic solid state detectors,” — Priscilla Cushman, Professor, University of Minnesota

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• “At these extremely low temperatures, our installed detectors can now scan a whole new region of parameter space where the lightest dark matter particles may be lurking.” — Priscilla Cushman, Professor, University of Minnesota

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This milestone in the SuperCDMS project represents a crucial step in the ongoing quest to understand dark matter and its role in the universe.

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