Dedman College of Humanities and Sciences Dedman College Research Faculty News Physics

Dark Matter is a huge mystery. This device is trying to detect it.

National Geographic

Originally Posted: October 8, 2018

Jodi Cooley, a physicist at Southern Methodist University and a principal investigator at the SuperCDMS dark matter detector was quoted in this article.

In an otherwise unassuming facility in northern Seattle, a supercooled tangle of tubes and wires is poised to remake the world. Coursing with liquid helium, the device’s interior hovers less than a tenth of a degree above absolute zero, the coldest possible temperature. Inside the frigid cavity, carefully shielded from noise, microwave radiation can resonate like sound waves in a bell, hunting for hints of particles whizzing through that, in all other contexts, would be invisible.

Meet the Axion Dark Matter eXperiment, or ADMX: the most sensitive scientific instrument of its kind ever built. If ADMX confirms the existence of its prey, a theoretical particle called the axion, it could finally explain the massive cosmic mystery of dark matter.

Scientists have been searching for this strange substance for decades, when observations of the universe revealed that all the visible matter we see is actually outnumbered six to one by mysterious, inert stuff we can only detect via its gravitational tug. Unlike normal matter, we don’t know what dark matter is made of yet. So like Ghostbusters tracking an irksome spectre, scientists are using the best theories about dark matter to build elaborate detectors, trying to catch the phantom by whatever glimmer it leaves behind.

ADMX has been more than 30 years in the making; it took that long for this kind of detector to reach the sensitivity that scientists think they need to nab the axion.

“The ingenuity and cleverness it takes to design and build these experiments is just fantastic to me, and that gets so little credit”, says Stanford University physicist Helen Quinn, whose theories laid the groundwork for the axion in the 1970s. “This is an incredible piece of experimental work”.


For decades, the leading candidates for dark matter were antisocial things called weakly interacting massive particles, or WIMPs for short. Not only did some theories predict these extra particles, but they also had just the right properties you’d expect dark matter to have—a coincidence called the “WIMP miracle”. What’s more, WIMPs could be plausibly tested with technology we already understood, such as particle colliders and neutrino detectors.

Despite WIMPs’ allure, searches for them have so far come up empty. The silence is unnerving, to the point that some researchers are calling for a new era in the search for dark matter.

“I don’t want to knock [WIMPs] at all: We need to continue to investigate that paradigm, because we haven’t exhausted it yet”, says Jodi Cooley, a physicist at Southern Methodist University and a principal investigator at the SuperCDMS dark matter detector. “But while we’re still investigating, we should be looking at new, fresh ideas”. READ MORE