Trapped antiprotons in ultra-high vacuum Penning traps are a key ingredient for high-precision tests of CPT invariance by comparing the fundamental properties of protons and antiprotons. The BASE collaboration has pushed the sensitivity frontier of these tests using an advanced multi-Penning trap system located in the Antimatter Factory of CERN to determine the charge-to-mass ratio and magnetic moment of the antiproton and compare these values to those of the proton. The sensitivity of these measurements has reached 16 ppt and 1.6 ppb, respectively [1, 2] – a level from where magnetic field fluctuations from the facility operation pose a limit on the achievable precision.

To counteract this limitation, we have taken the strategic decision to develop transportable antiproton traps to continue measurements in a low-noise magnetic field environments, currently under development at Heinrich Heine University Düsseldorf. In parallel, methods for coherent spin-spectroscopy of a single trapped antiproton were developed in the BASE CERN experiment [3], a technological milestone towards antiproton magnetic moment measurements on the p.p.t.-level.

In this talk, I will present the first road transport of protons [4] and antiprotons in the transportable Penning trap system BASE-STEP, the major ingredient to realize operation of offline antiproton experiments. Further, I will discuss the methods developed at the BASE precision trap system at CERN, that demonstrate that higher precision can be achieved in offline laboratories. I will also summarize the BASE experimental program during the upcoming long shutdown 3 of CERN.

References:
[1] C. Smorra et al., Nature 550, 371–374 (2017).
[2] M. J. Borchert et al., Nature 601, 53–57 (2022).
[3] B. M. Latacz et al., Nature 644, 64–68 (2025).
[4] M. Leonhardt et al., Nature 641, 871–875 (2025).