AEgIS Collaboration Meeting at CERN Reviews Breakthroughs and Sets Strategy for 2026
The AEgIS collaboration convened at CERN from 10–12 December for its annual collaboration meeting, bringing together researchers to review a year of major experimental progress and to define priorities for the 2026 physics programme. The meeting was jointly led by AEgIS spokesperson Dr. Ruggero Caravita and Dr. Benjamin Rienäcker, AEgIS Physics Coordinator.
A central focus of the meeting was the transition of AEgIS from proof-of-principle demonstrations to a mature, high-efficiency experimental phase. In particular, significant progress was reported on positronium laser cooling, which has been refined through the implementation of cryogenic pre-cooling of the positronium production target. This development represents a crucial step toward producing colder antihydrogen beams with well-controlled kinematics.
Dr. Rienäcker led discussions on how these technical advances translate into precision measurements, emphasising that positronium cooling will be a robust and integral component of the antihydrogen production chain. Its integration into the full AEgIS cycle will be essential for the experiment’s primary objective: a direct measurement of the gravitational acceleration of antimatter.
A major contribution from the University of Liverpool’s QUASAR Group was presented by Bharat Rawat and Sruthy Chandran, focusing on advanced numerical modelling of antiproton transport. Their work concentrates on optimising the delicate transfer of antiprotons from the 5 T catching region to the 1 T experimental region, a precision manoeuvre that is critical for the formation of a well-defined antihydrogen beam. The long-term goal is the development of a full digital twin of the AEgIS experiment, enabling predictive, start-to-end optimisation and a reduction of systematic uncertainties.
Beyond antihydrogen, the collaboration discussed several complementary physics and infrastructure programmes. These include BOREALIS, which aims to inject ions into AEgIS for co-trapping with antiprotons to enable efficient antiproton cooling; FANTASIA, focused on the backward extraction of antiprotons for external trapping in a Paul trap, allowing dedicated studies in low magnetic field environments; and the development of a new anion source from Toruń, envisioned as a future successor to BOREALIS. Novel studies of trapped non-neutral plasmas within AEgIS were also reported.
A key highlight of the meeting was the commissioning of the complete moiré deflectometer system, MEDUSA, which represents a major milestone for the experiment. MEDUSA combines rotatable and alignable moiré gratings with a suite of state-of-the-art detectors: OPHANIM, developed by the TU Munich team, providing sub-micrometre single-antiproton annihilation position resolution; SARA, from Politecnico di Milano, delivering precise timing information; and J-PET, from the Jagiellonian University, enabling reconstruction of the annihilation position along the beam axis. The system can be fully calibrated using white-light techniques. Commissioning with antiprotons has demonstrated the capability of MEDUSA to resolve gravitational effects, marking a decisive step toward the core AEgIS gravity measurement.
Professor Carsten P. Welsch, who leads the Liverpool contribution, highlighted the strength of the collaboration, noting that the close integration of laser physics, beam dynamics, detector development, and simulation has positioned AEgIS as one of the most versatile antimatter experiments worldwide.
With these advances, AEgIS enters 2026 with a mature experimental infrastructure and a clear strategy for precision tests of fundamental physics using antimatter.