Scientists Just Drove 92 Particles of Antimatter Across CERN in a Truck

Subtitle: The BASE collaboration loaded a cryogenic Penning trap onto a truck, drove about eight kilometres around CERN’s Meyrin site, and brought every antiproton home — a world first published in Nature.

Antimatter usually stays where it is made. Touch ordinary matter and it vanishes in a flash of energy. Until March 24, 2026, every precision study of low-energy antiprotons had to happen inside CERN’s Antimatter Factory — the only place on Earth that can produce, store, and hand them to experiments.

That day, the BASE collaboration did something that sounds like science fiction and reads like logistics: they trapped 92 antiprotons in a portable cryogenic Penning trap called BASE-STEP, loaded the roughly one-tonne apparatus onto a truck, and drove it around the laboratory’s main site for about half an hour. Distance: roughly eight kilometres. Losses: zero.

On September 16, 2026, the team — led from Heinrich Heine University Düsseldorf (HHU) with CERN and partners across Europe and Japan — reported the result in Nature. Lead author Marcel Leonhardt, BASE-STEP principal investigator Christian Smorra, and BASE spokesperson Stefan Ulmer frame it as a dress rehearsal for a much bigger move: taking antimatter out of a noisy accelerator hall and into quiet precision labs where the matter–antimatter comparison can finally get sharper.

Why move antimatter at all?

According to the simplest reading of the Big Bang, the early universe should have made equal amounts of matter and antimatter. Those equal-but-opposite particles should have annihilated, leaving emptiness. Instead we live in a universe of matter. Physicists hunt for tiny differences between particles and their antiparticles that might explain the imbalance.

BASE has already pushed those comparisons extraordinarily far. Ulmer notes recent magnetic-moment measurements at 0.3 parts per billion for protons and 1.6 parts per billion for antiprotons — still no difference within reach. The bottleneck is no longer the trap’s cleverness. It is the neighbourhood.

“The machines and equipment in CERN’s ‘antimatter factory’… generate magnetic field fluctuations that limit how far we can push our precision measurements,” Ulmer said in CERN’s announcement. Those wiggles are minuscule — on the order of a billionth of a tesla, tens of thousands of times weaker than Earth’s field — yet they are fatal to the next decimal places. Smorra’s diagnosis is blunt: accuracy cannot improve further at the Antimatter Factory. Better conditions exist only outside.

The collaboration’s answer is BASE-STEP: a compact, open, transportable Penning trap designed to accept antiprotons, survive disconnection and road vibration, and later inject them into offline experiments. A prior proton run in October 2024 (published in Nature in 2025) proved the truck concept with ordinary matter. March 2026 was the antimatter leap.

What a Penning trap has to survive on the road

A Penning trap holds charged particles with a combination of static magnetic and electric fields inside an ultrahigh vacuum. BASE already holds records for keeping antiprotons confined for more than a year in its main apparatus. BASE-STEP had to be different: small enough to fit through ordinary lab doors and onto a truck, rugged enough for bumps, and cold enough to keep a superconducting magnet happy.

CERN describes the current package — superconducting magnet, liquid-helium cryogenics, power reserves, and vacuum chamber — as weighing about 1,000 kilograms, far more compact than the main BASE setup. During the Meyrin loop, continuous monitoring showed every antiproton still accounted for after unloading. The team then kept storing and manipulating the cloud for more than a month.

Vacuum quality was not a footnote. Collisions with residual gas destroy antiprotons. Leonhardt reports a vacuum better than 2.2 × 10⁻¹⁸ mbar throughout the storage period — a world first for an open trap that can inject and extract antiprotons, and substantially better than the collaboration’s own design target of 1 × 10⁻¹⁶ mbar. HHU’s timeline graphic notes that on day 27, a single antiproton annihilated during a deliberate extraction test — not during the road trip.

What this is — and what it is not

It is not a handheld antimatter battery, a warp-drive fuel demo, or proof that antimatter can be shipped like dry ice. Ninety-two particles is a microscopic sample by everyday standards. The March run stayed on CERN’s site. Transferring antiprotons into a destination experiment without losing them remains, in Smorra’s words via CERN, one of the hardest remaining steps. An eight-to-ten-hour haul to Düsseldorf will need more autonomy: a generator and cryocooler to keep the magnet below about 8.2 K for the full journey.

It is peer-reviewed evidence that trapped antiprotons can leave the Antimatter Factory by road without loss, keep an extreme vacuum, and remain experimentally usable for weeks afterward. Nature’s abstract puts the Meyrin route at 7.5 km; institutional briefings round it to about eight. Either way, the point is lossless relocation under real traffic conditions — the previously untested link in the offline-measurement plan.

CERN Research Director Gautier Hamel de Monchenault called the milestone pioneering. The collaboration’s next targets are injection into an offline experiment at CERN, then transport toward HHU’s new high-precision laboratory — with Leibniz University Hannover and other quiet sites also on the longer map. Smorra expects offline conditions to enable at least a 100-fold gain in proton–antiproton comparison precision. HHU notes the same March run may eventually open the door to moving still more exotic species, such as antideuterons or antihydrogen molecular ions.

The strange practicality of an impossible cargo

The shareable image is almost mundane: a truck, a crate-sized cryogenic machine, a mobile control panel showing that the cloud is still there. Barbara Latacz’s team photo — Khwaish Anjum, Smorra, Jonathan Morgner, Leonhardt standing with BASE-STEP ready to load — looks like any other instrument move. The physics underneath is anything but ordinary.

Antimatter annihilates on contact with matter. The universe should not prefer our side of the ledger. The only factory that makes usable low-energy antiprotons sits inside a magnetic thunderstorm of its own making. So the scientists built a quieter future the old-fashioned way: pack carefully, disconnect, drive, unload, count.

Ninety-two particles took a road trip. All of them came back.

That is how you begin to ask, with better instruments, why anything came back from the Big Bang at all.

Sources

Leonhardt, M., Morgner, J., Abbass, F., et al.; Ulmer, S.; Smorra, C. (corresponding). (2026). Road transport of trapped antiprotons. Nature. https://doi.org/10.1038/s41586-026-11019-z
CERN. (2026, March 24). BASE experiment at CERN succeeds in transporting antimatter. https://home.cern/base-experiment-cern-succeeds-transporting-antimatter/
Heinrich Heine University Düsseldorf / Claussen, A. (2026, September 16). Antiproton storage and transport records achieved. https://www.hhu.de/en/about-hhu/press-and-marketing/current-news/press-releases-hhu/news-detailansicht/antiproton-storage-and-transport-records-achieved
HHU / Ulmer group. (2026, September 16). World-first transport of antiprotons published in Nature. https://www.hhu.de/news/world-first-transport-of-antiprotons-published-in-nature
idw / HHU press distribution. (2026, September 16). Antiproton storage and transport records achieved. https://idw-online.de/en/news877506