Searching for dark matter, deep in the Earth
Get the full intelligence
Search transcripts, export clips, track mentions, and explore all topics from “Searching for dark matter, deep in the Earth” inside PodZeus.
In this episode of Science Friday, host Flora Lichtman explores the search for dark matter with Dr. Priscilla Cushman, spokesperson for the Super CDMS experiment at the Soudan Underground Laboratory in Minnesota. While dark matter makes up about 85% of the universe’s matter, it remains elusive due to its weak interactions with normal matter. The experiment uses ultra-sensitive detectors made of germanium and silicon crystals, cooled to just 30 millikelvin—near absolute zero—to detect the faintest energy signals from dark matter particles passing through Earth. These particles, moving at high speeds relative to us, create microscopic nuclear recoils that generate unique pulse signatures in superconducting sensors. The team is currently in the commissioning phase, calibrating detectors and preparing for the first science run, expected to begin in summer 2026. Dr. Cushman emphasizes that dark matter may not be a single particle but a diverse 'cosmic junk drawer' of candidates—including axions, lighter particles, or even wave-like phenomena—challenging previous theories like supersymmetry. The quest is as much philosophical as scientific, driven by the profound mystery of a universe we can’t fully see but whose gravity we can feel.
Dark matter is everywhere, including in the room with us, but we only detect it through rare, faint interactions with nuclei in ultra-sensitive underground detectors.
Super CDMS uses cryogenic detectors cooled to 30 millikelvin to minimize thermal noise and enable detection of minuscule energy depositions from dark matter particles.
The experiment’s success depends on both extreme cold and a massive cryogenic infrastructure, including nested vacuum cans and superconducting sensors.
Dark matter may not be a single particle but a diverse set of candidates—possibly including axions, light particles, or even wave-like entities—making the search multidimensional.
The absence of WIMPs (weakly interacting massive particles) at the LHC suggests nature is more complex than early models predicted, opening new frontiers in physics.
The Cosmic Mystery of Dark Matter
“Dark matter makes up 85% of the stuff of the universe. We know a lot about it from gravity. But what we don’t know is how it interacts with standard model particles.”
The Super CDMS Experiment: Deep Underground
Dr. Priscilla Cushman describes the Super CDMS experiment located two kilometers beneath the Earth’s surface in the Soudan Mine. She explains why depth is critical—shielding detectors from cosmic rays—while dark matter particles pass through unimpeded.
How Dark Matter Interacts with Matter
“Imagine you're standing in the middle of a large stadium. The nucleus would be like putting a little grape down in the middle. And all the electrons are out at the edges of that stadium.”
The Cryogenic Challenge: Cooling to Near Absolute Zero
“It's actually not unusually cold for physics experiments. But the payload of 31 kilograms of detectors and hundreds of kilograms of supporting hardware at millikelvin temperatures is what makes it unique.”
Detecting the Invisible: The Pulse Signature
When a dark matter particle interacts with a nucleus, it creates a vibration that spreads through the crystal and is detected by thousands of transition-edge sensors. The shape, rise time, and width of the resulting microsecond-long pulse reveal the nature of the interaction.
“I think that's the most likely explanation, honestly. When we talk about how much there should be, we're always talking about a mass density. But what we don’t know is how it interacts with standard model particles.”
“Dark matter makes up 85% of the stuff of the universe. We know a lot about it from gravity. But what we don’t know is how it interacts with standard model particles.”
“It's sort of like a known unknown. We know there is this treasure trove of new discoveries to be made. And I just know that's where the next breakthrough will be.”
Host
Guest
Dr. Priscilla Cushman
person
Super CDMS
other
Science Friday
media
WIMPs
other
Soudan Underground Laboratory
other
axions
other
germanium
other
transition edge sensors
other
helium dilution refrigerator
other
LHC
other
Harnessing the superpowers of silk
Science Friday • 18m • 3/31/2026
How to poop better, according to a gastroenterologist
Science Friday • 28m • 4/1/2026
Should Pluto be a planet again?
Science Friday • 19m • 4/2/2026
Artemis II test flight heads toward the moon
Science Friday • 18m • 4/3/2026
Can algae help pull microplastics out of our water supply?
Science Friday • 13m • 4/6/2026
Get the full intelligence
Search transcripts, export clips, track mentions, and explore all topics from “Searching for dark matter, deep in the Earth” inside PodZeus.
Start discovering podcast insights today
Start with a 7-day trial and explore a growing catalog of popular podcasts. No credit card required.
No credit card required • 7-day trial • Cancel anytime