CERN took antimatter on a historic road trip

In a universe where nearly everything comprises matter, one anomaly stands out—antimatter. It is the mirror image of what makes up entire galaxies, planets, and life. Preserving it has long been challenging for scientists as it annihilates upon contact with ordinary matter. Recently, however, a team of researchers achieved a remarkable feat: taking antimatter on its first-ever road trip.

Researchers from the Baryon Antibaryon Symmetry Experiment (BASE) at CERN, the European Organization for Nuclear Research, successfully transported a cloud of  92 antiprotons across the laboratory’s campus in Geneva, Switzerland. It was made possible through a portable cryogenic Penning trap, which is a special container that keeps the antiproton extremely cold and protected from ordinary matter, so it would not vanish during the short journey.

Although the trip lasted less than half an hour, it marked the first step toward delivering antimatter to other European laboratories, such as Heinrich Heine University Düsseldorf (HHU), where antiproton properties are measured with far greater precision.

A particle from sci-fi

The universe that we know of shouldn’t exist. Physicists suggest that when the universe began from the Big Bang, equal amounts of matter and antimatter were created. In theory, these polar opposites should have annihilated each other instantly. As such, scientists have been boggled as to why everything—from galaxies to life—is made predominantly of matter.

Antimatter seems like something out of science fiction, but it somehow exists within nature. It was first discovered in 1932 by American physicist Carl D. Anderson, who identified the positron (anti-electron) naturally occurring in cosmic rays. It is nearly identical to ordinary matter, except the electric charge and magnetic moment are reversed.  

What makes antimatter difficult to study is its volatility and instability. Even the slightest  contact with a regular matter, whether a molecule in the air or walls of a container,  causes both to annihilate instantly in a burst of energy. That is why antimatter cannot simply exist freely within nature.

CERN: Antimatter factory

Although antimatter is extremely rare in the universe, scientists at CERN have learned to create it in minute amounts under controlled conditions. Globally, CERN’s antimatter factory remains the only facility where antiprotons are routinely produced, stored, and studied. 

At the heart of the facility are two successive decelerators: the Antiproton Decelerator (AD) and the Extra Low Energy Antiproton ring (ELENA), which slow antiprotons to extremely low energies. The lower their energy, the easier they are to trap and study. Afterwards, these antiparticles are confined using powerful magnetic fields, preventing contact with normal matter. 

Through CERN’s Antiproton Decelerator, scientists have even created antihydrogen—an atom composed of an antiproton orbited by a positron. Though it was sustained briefly, fractions of a second were long enough to advance the studies of antimatter.

However, producing lots of antimatter is incredibly expensive and inefficient. Estimates suggest that making one gram of antihydrogen can cost around 62.5 trillion US dollars. In reality, all antimatter created so far is only a few nanograms, far less than a single gram.

Moreover, CERN is stuck with another issue. According to Stefan Ulmer, Spokesperson of Base, the antimatter factory generates magnetic field fluctuation that limits the precision of measurements.

To overcome this limitation, researchers developed the BASE-STEP trap, which is an apparatus designed to transport antiprotons to an offline space and share it with other laboratories.

“Our aim with BASE-STEP is to be able to trap antiprotons and deliver them to our precision laboratories at a dedicated space at CERN, HHU, Leibnitz University Hannover and perhaps other laboratories that are capable of performing very-high-precision antiproton measurements, which unfortunately is not possible in the antimatter factory,” explains Christian Smorra, the Leader of BASE-STEP. 

Antimatter hits the road

Transporting antimatter is far from ordinary. Researchers are extra careful when containing antiprotons, as any contact with ordinary matter would result in annihilation. 

BASE-STEP is compact enough to be loaded onto a truck and pass through laboratory doors. It is engineered to withstand the disturbances and vibrations of transport.

Furthermore, the apparatus is equipped with a superconducting magnet, liquid helium cryogenic cooling, power reserves, and a vacuum chamber. Together, these components trap the antiparticles using magnetic and electric fields.  

Weighing around 1,000 kilograms, BASE-STEP is much more compact than conventional antimatter research systems, making it fit for truck transportation.

However, antimatter’s road trip presents additional challenges. As the superconducting magnet needs to be below 8.2 Kelvin for the whole trip, the truck needs to be loaded with a generator to power a cryocooler, which researchers are currently investigating.

“To reach our first destination – our dedicated precision laboratory at HHU in Germany –  would take us at least 8 hours. This means we’d have to keep the trap’s superconducting magnet at a temperature below 8.2 K for that long. So, in addition to the liquid helium, we’d need to have a generator to power a cryocooler on the truck. We are currently investigating this possibility,” emphasized Smorra.

Why antimatter matters 

Beyond laboratories, antimatter is currently applied in the real-world. One example is Positron Emission Tomography (PET) scan, where radioactive substances emit positrons that annihilate with electrons, producing detectable gamma rays. These signals are used by doctors to generate detailed images of organs and tissues.

Looking further ahead, antimatter can possibly be used for space exploration. Because matter-antimatter annihilation releases immense energy, scientists have envisioned it as the ultimate rocket fuel. Having a few grams of antimatter could, in theory, propel spacecraft to near-light speeds. For now, however, this remains as science fiction as producing even milligrams is beyond current technological capabilities.

At the same time, antimatter research remains a difficult path. Yet with continued advances in accelerator technology, magnetic traps, and detection methods, scientists might be able to generate large amounts of antiparticles.

“Transporting antimatter is a pioneering and ambitious project, and I congratulate the BASE collaboration on this impressive milestone. We are at the beginning of an exciting scientific journey that will allow us to further deepen our understanding of antimatter,” says CERN Director for Research and Computing, Gautier Hamel de Monchenault.

Antimatter’s first road trip may have been short, but it’s definitely a giant step for science. Each careful journey brings us closer to understanding this mysterious particle, and how it could one day help advance the world of medicine, research, and even space exploration.