CERN’s antimatter factory, located in a high-magnetic field environment and a vacuum more extreme than interstellar space, houses some of the most delicate matter found on Earth. Nestled in a compact box roughly the size of a filing cabinet and a few hundred kilograms lighter than a Ford Focus, lie antiprotons that have been quietly resting for weeks. Rather than being aggressively tested like most particles produced in this facility, these antiprotons have a singular purpose: awaiting their moment of transport.

Shortly, more than a hundred of these precious antimatter particles will be transported in trucks along a four-kilometer ring road around the CERN campus. This marks the inaugural demonstration of a future antimatter delivery service designed to transport antimatter to laboratories across Europe.

During my visit to CERN’s campus near Geneva, Switzerland, project leader Christian Smolla guided me through the facility, showcasing the final preparations for the “Symmetry Test in Transportable Antiproton Experiments (STEP).” “This represents a groundbreaking achievement in antimatter science,” he remarked. “While the theoretical framework for transporting antiprotons existed since the facility’s inception, this is the first practical implementation.”

Since the 1920s, scientists have acknowledged the existence of antimatter, particles with counterparts that possess opposite charges. However, antiprotons, being the simplest form of antimatter, often annihilate upon contact with their more plentiful proton counterparts, complicating their production and storage. It wasn’t until the 1980s that CERN successfully conducted the first experiments to confine antiprotons, generated by proton bombardment of metal targets.

Today, CERN’s Antimatter Factory is the only location globally capable of producing millions of antiprotons on demand and retaining them for research purposes. Several experiments, including the Baryon Antibaryon Symmetry Experiment (BASE), take place here, with STEP also participating.

These experiments meticulously test antimatter’s fundamental properties, examining deviations from normal matter. Insights gleaned could provide answers to why our universe predominantly consists of matter, seemingly devoid of antimatter.

To achieve the necessary precision in measurements, it is essential to mitigate noise from radiation that might disrupt data collection. When antiprotons enter the detection zone, they approach nearly the speed of light, necessitating a robust magnetic field for deceleration, although complete blockage remains unattainable.

In 2018, Smolla’s team recognized the need for a quieter environment for antimatter, resulting in a strategic escape plan. “Observing variations in the magnetic field made it clear we had to continue precision measurements elsewhere,” Smolla stated.

Containing antimatter is a formidable challenge, requiring superconducting magnets cool enough to sustain near absolute zero temperatures while consuming massive electrical power. The STEP design leveraged just a 30-liter liquid helium tank for magnet cooling, allowing its electronics to function on a standard diesel generator. Future test runs aim to transition to battery power.

Additionally, magnets needed to withstand start-stop movements during operation, and a custom vacuum system was essential to ensure the antiprotons remain uncontaminated by normal matter during their loading and unloading processes.

In 2024, Smolla’s team is set to showcase the STEP experiment. A truck will transport the device across the CERN campus to observe protons, a significant milestone in antimatter transport.

In the days leading up to my visit, approximately 100 antiprotons were slowed and positioned within a sophisticated network of vacuum and electromagnetic fields.

Since then, they’ve patiently awaited the next steps within a complex arrangement of electrical wires and liquid helium lines. With a small oscilloscope screen, Smolla’s team monitors the antimatter’s vital signs. The natural frequencies at which antiprotons vibrate manifest as double humps, affectionately adorned with googly eyes.

On an early Tuesday morning, a crane carefully hoists the entire 850-kilogram trap onto a specialized truck. The truck’s operator is trained to manage CERN’s sensitive equipment, ensuring smooth acceleration and braking.

The truck will then navigate a four-kilometer loop around the CERN campus before returning to the antimatter factory. Should the experiment prove successful, Smolla’s ultimate goal is to extend this antimatter transport service beyond CERN’s confines, delivering antimatter capsules to various European laboratories. A facility currently under construction at Heinrich Heine University in Düsseldorf, Germany, aims to study antimatter in a near-field-free environment.

However, this ambitious goal entails several years of work. CERN is scheduled to suspend extensive operations in July to upgrade its Large Hadron Collider for higher power outputs, a task slated for completion in late 2028.

Once operational, the antimatter delivery service could mean trucks transporting antimatter alongside ordinary vehicles on highways throughout Switzerland and Germany. Though it sounds alarming—given antimatter’s tendency to annihilate upon contact with regular matter—Smolla assures that the risk remains minimal.

“Transporting antimatter is safe, as the quantities we handle are extremely small,” Smolla explains. “You could easily lose 1,000 antiprotons without any noticeable impact.”