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| CERN scientists will soon get antiprotons ready for a road trip. (Mark Garlick/Getty Images) |
This marks the first time that loose particles have been transported like this, and it paves the way for a method of shipping antimatter from CERN to facilities that can study it with greater precision than ever before.
Antimatter doesn't travel well – after all, it tends to just annihilate any container you stick it in. But scientists at CERN have developed a specialized trap they call BASE-STEP, which could hold and transport this strange stuff.
In late October, the team demonstrated that BASE-STEP works as planned, by loading a cloud of 70 unbonded protons into the trap, loading that onto a truck, and driving it across CERN's main site. Thankfully, the fragile cargo survived the short trip.
"If you can do it with protons, it will also work with antiprotons," says CERN physicist Christian Smorra, the leader of BASE-STEP. "The only difference is that you need a much better vacuum chamber for the antiprotons."
Antimatter is kind of the 'evil twin' of regular matter – the main difference is that a particle and its antiparticle have the opposite charge. It sounds simple, but the ramifications are huge. If antimatter particles touch those of normal matter, even air, they annihilate each other in a burst of energy.
As a result, antimatter usually has a fleeting existence, meaning it's hard to make and even harder to study. CERN's Antiproton Decelerator (AD) is one of the few places on Earth that can consistently create antimatter, and it's then fed into a series of nearby experiments that examine it in different ways.
To store the stuff long enough to study it, antimatter needs to be suspended in an electromagnetic field to keep it from touching the sides. The BASE experiment does just this, and it can store antimatter particles for well over a year. However, there are only so many experiments that can be done on-site.
"The accelerator equipment in the AD hall generates magnetic field fluctuations that limit how far we can push our precision measurements," says CERN particle physicist Stefan Ulmer.
"If we want to get an even deeper understanding of the fundamental properties of antiprotons, we need to move out."
That's why CERN built BASE-STEP, a smaller, portable version that's 1.9 meters (6.2 feet) long, or just one-fifth the size of BASE. It's designed to protect antiparticles from the bumps and shakes you'd expect during a road trip, and to do so there's a lot of gear crammed into that small space.
BASE-STEP packs a vacuum chamber to hold the antiparticles, a superconducting magnet to create the electromagnetic fields needed to suspend them, a cryogenic system that uses liquid helium to cool that magnet, and batteries to run the whole thing.
For this first test run, the scientists didn't use antimatter particles but 70 loose protons, which are also sensitive to shock. These unbonded particles are just itching to form new bonds, so if they jostle around too much, they'll be pulled back into atomic nuclei. They're far less valuable to lose if they don't make it.
The run was successful, with the protons making their journey by truck across the compound. After a bit more tweaking, the team plans to transport its first load of antimatter next year. A separate experiment called PUMA is also aiming to do the same thing in 2025.
"Eventually we want to be able to transport antimatter to our dedicated precision laboratories at the Heinrich Heine University in Düsseldorf, which will allow us to study antimatter with at least 100-fold improved precision," says Smorra.
"In the longer term, we want to transport it to any laboratory in Europe. This means that we need to have a power generator on the truck. We are currently investigating this possibility."
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