CERN researchers are set to transport around 100 antiprotons by truck around the campus near Geneva, Switzerland, on Tuesday. This marks the first demonstration of a planned antimatter delivery service to labs across Europe. The experiment, known as STEP, aims to enable precision measurements away from the noisy antimatter factory.
The Symmetry Tests in Experiments with Portable antiprotons (STEP) is part of CERN's Baryon Antibaryon Symmetry Experiment (BASE). Project leader Christian Smorra described it as “groundbreaking for antimatter science,” noting that the concept of transporting antiprotons has existed since the facility's start but is now feasible for the first time. Antiprotons, the antimatter counterparts to protons known since the 1920s, were first confined at CERN in the 1980s. CERN's Antimatter Decelerator remains the world's only facility producing millions of them on demand for seven experiments probing matter-antimatter asymmetry, which could explain the universe's matter dominance. In 2018, Smorra's team identified magnetic field interference at the factory hindering precision tests. They developed a portable trap using a 30-litre liquid helium tank, battery power for the test, and a custom vacuum system to handle road vibrations. Earlier in 2024, the setup successfully transported regular protons around the campus. About a week ago, roughly 100 antiprotons were loaded into the 850-kilogram device. On Tuesday morning, a crane will load it onto a specially driven truck for a 4-kilometre loop back to the factory. Success could lead to deliveries to sites like Heinrich Heine University Düsseldorf, though CERN's Large Hadron Collider upgrade from July will delay this until late 2028. Smorra emphasized safety: “There’s nothing dangerous about the transport of antimatter, because the amount that we are transporting is so small. If you transport 1000 antiprotons and it gets lost, you won’t even notice it.”