Here, muons are used to detect hidden material, such as metals that are denser and can typically be used to for nuclear equipment.
The device takes advantage of charged particles called muons, which are created in the atmosphere and zip through every square centimeter of material on Earth — human bodies and armored trucks alike — at a rate of one per minute.
“They sort of rain upon us like a light drizzle all the time,” Hohlmann said.
Despite their high energies, muons don’t interact very strongly with matter. “They can go through 6 to 8 feet of steel without being stopped,” Hohlmann said. “That’s nice for our application, because what we’re trying to do is look into things that are shielded.”
But though matter typically doesn’t stop muons in their tracks, heavy elements like uranium and metals like lead can deflect the charged particles. By tracking the muons’ paths, scientists can construct a 3-D image of whatever material got in their way.
So here's another example when someone asks you if research in high energy physics is a waste of time and money.
Edit: I found the link to the conference proceeding paper by the author mentioned in the Wired article. Not sure if it is open access, though.