Science Friday Searching for dark matter, deep in the Earth
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May 4, 2026 
Dr. Priscilla Cushman, an experimental particle physicist leading the SuperCDMS SNOLAB effort, discusses installing ultra-cold germanium and silicon detectors deep in a nickel mine. She talks about why going 6,800 feet underground reduces background noise. Listens to how millikelvin temperatures and pulse shapes help spot rare nuclear interactions. Covers timelines for commissioning and the search for multiple dark matter possibilities.
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Daily Life As A Deep Underground Researcher
- Priscilla Cushman described traveling about a kilometer underground in miner coveralls with a 20-pound self-rescuer to reach the lab two kilometers below the surface.
- She emphasized the practical realities of working deep underground rather than a stereotypical lab coat image, illustrating daily access challenges.
Why The Lab Is Deep Underground
- Deep placement shields detectors from cosmic rays while letting weakly interacting dark matter pass through the Earth to the lab.
- Cushman explained detectors would see the same dark matter flux day or night because particles traverse Earth unimpeded.
Dark Matter Feels Like A Wind
- From our frame dark matter appears as a fast-moving wind because the Earth and solar system move through a halo of dark matter.
- Only about one in a trillion dark matter particles passes close enough to a nucleus to cause a detectable interaction.