Shedding Light on Dark Matter

Case Western Reserve researchers have designed a 20-ton liquid xenon WIMP detector to study dark matter.

Don’t let the name fool you—weakly interacting massive particles, or WIMPs for short—could be the very glue that holds galaxies together. While scientists believe these tiny particles provide the mass that keeps galaxies, including our own Milky Way, from flying apart, little else is known about these elusive bits of dark matter.


"We know it’s out there, we just don’t know what it is," says Tom Shutt, a Case Western Reserve physicist and a member of Case Western Reserve's Center for Education and Research in Cosmology and Astrophysics, part of the university's Institute for the Science of Origins.

Scientists believe WIMPs originated with the rest of the universe in the Big Bang. But the particles are hard to detect because they don’t give off radiation. And rather than interacting with regular matter, they pass through it unimpeded. In fact, researchers believe WIMPs could be streaming through us by the billion every second.

With a $3.2 million grant from the National Science Foundation, Shutt’s group, including fellow physicist Dan Akerib, has designed a 20-ton WIMP detector called LZD, which is designed to spot WIMPs colliding with xenon atoms. Such a collision, according to the team, would produce a minute flash of light that the detectors would locate, amplify and analyze.

Previous tests of a smaller detector have observed collisions between single neutrons and liquid xenon atoms. Researchers say LZD would be even more sensitive, by three orders of magnitude, giving the experiment acuity akin to seeing an ant in the span of the Milky Way.

Chasing down these needles in the sub-atomic haystack could help scientists answer big questions about the origins of the universe—and its inhabitants.

"This is very much connected to big philosophical questions: What are we made of? What did we come from?" Akerib says.

The study will be the world’s largest, most sensitive experiment on dark matter, and the bigger the detector, the more likely it will be to see WIMPs. "It’s like using a larger light collector in a telescope," says Akerib. "It increases your chances of seeing what you want to see."

Scientists expect the technology that gave rise to LZD could lead to another class of super-sensitive detectors for medicine and global security.