Antimatter Gravitation Studies with Trapped Antihydrogen

by William Alan Bertsche (University of Manchester (GB))

Wednesday 15 May 2024, 13:30 → 14:30 Europe/London

Small Lecture Theatre (Poynting)

The apparent predominance of matter in the Universe is a lingering problem that has plagued physicists practically since the discovery of antimatter. The ALPHA Collaboration performs precision atomic physics measurements with trapped antihydrogen atoms to try to shed light on this problem with Baryon symmetry. It has recently published the first results from ALPHA-g, an apparatus dedicated to making direct measurements of the gravitational effect on the trajectory of antiparticles using neutral antimatter [1]. This first-of-a-kind direct test of the free-fall Weak Equivalence Principle definitively measures the effect of gravitational acceleration on antimatter. With a best-fit value of the effective gravitational acceleration of antihydrogen of (0.75 ± 0.13 (stat. + syst.) ± 0.16 (simulation)), it finds consequent motion of antimatter consistent with that expected of matter. We present a brief background of this effort in the context of experiments conducted to date at ALPHA and explain the underlying principle of the magnetic bias technique used to probe the gravitational behavior of the anti-atoms in our trap. We explain the experimental techniques used to realize the measurement and present the experimental results and analysis in detail. Finally, we outline the future direction of gravitation measurements performed with ALPHA-g.

 

 

[1] Anderson, E.K., et al. (ALPHA Collaboration) Observation of the effect of gravity on the motion of antimatter. Nature 621, 716–722 (2023). https://doi.org/10.1038/s41586-023-06527-1