Proton transport from the antimatter factory of CERN

Precision measurements using low-energy antiprotons, exclusively available at the antimatter factory (AMF) of CERN ¹ , offer stringent tests of charge–parity–time (CPT) invariance, which is a fundamental symmetry in the Standard Model of particle physics ² . These tests have been realized, for example, in antiprotonic helium ³ and antihydrogen ⁴ . In our cryogenic Penning-trap experiments ⁵ , we measure the magnetic moments ^6,7 and charge-to-mass ratios of protons and antiprotons and now provide the most precise test of CPT invariance in the baryon sector ⁸ . Our experiments are limited by magnetic field fluctuations imposed by the decelerators in the AMF; therefore, we are advancing the relocation of antiprotons to dedicated precision laboratories. Here we present the successful transport of a trapped proton cloud from the AMF using BASE-STEP ⁹ —a transportable, superconducting, autonomous and open Penning-trap system that can distribute antiprotons into other experiments. We transferred the trapped protons from our experimental area at the AMF onto a truck and transported them across the Meyrin site of CERN, demonstrating autonomous operation without external power for 4 h and loss-free proton relocation. We thereby confirm the feasibility of transferring particles into low-noise laboratories in the vicinity of the AMF and of using a power generator on the truck ¹⁰ to reach laboratories throughout Europe. This marks the potential start of a new era in precision antimatter research, enabling low-noise measurements of antiprotons, the charged antimatter ions H ¯ + ¹¹ and H ¯ 2 − (ref.  ¹² ), and other accelerator-produced ions, such as hydrogen-like lead or uranium ions ^13,14 .