A prototype of a device that could someday detect nukes through layers of steel just passed its first test.
A prototype of a device that could someday detect nukes through layers of steel just passed its first test. The detector, which uses technology that was developed for particle physics experiments at the Large Hadron Collider, can tell the difference among iron, lead and other heavy metals.
By detecting the signature of heavy elements that could be used to build nuclear weapons, the new machine could someday find nuclear contraband hidden in shielded vehicles.
“This is the first time that we actually built and operated successfully the equipment to actually do this in real life, rather than in a computer,” said high-energy physicist Marcus Hohlmann of the Florida Institute of Technology, a co-author of the study.
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.
The new prototype uses detectors called GEMs, or Gas Electron Multipliers, to trace muons’ trajectories before and after they hit a bit of heavy material. The detectors are thin plates filled with gas that were originally developed for particle physics experiments at places like CERN and Fermilab. When a muon plows through the detector, it rips electrons from the gas, leaving a distinctive trail readable by electronics on the detector’s surface.
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Photo: Marcus Hohlmann | Wired