Speaker
Description
The ALPHA collaboration at CERN operates two machines dedicated to testing fundamental symmetries using trapped antihydrogen atoms. The ALPHA-2 experiment was built in 2012 and is optimized to perform high-precision spectroscopy on antihydrogen [1]. The ALPHA-g apparatus, completed in 2021, is designed to measure its gravitational acceleration [2]. In both instances, the physics signal is derived from the three-dimensional position (plus time) of the antihydrogen annihilation, called the vertex. The ALPHA-2 trap is surrounded by a microstrip silicon detector, while ALPHA-g by a time projection chamber. Both position-sensitive detectors are used to reconstruct the trajectories of charged pions produced in the antiproton annihilation process. This talk explores the tracking methods, and the techniques employed in the ALPHA experiment to reconstruct the annihilation vertex.
[1] Baker, C. J., et al. "Precision spectroscopy of the hyperfine components of the 1S–2S transition in antihydrogen." Nature Physics (2025): 1-7.
[2] Anderson, E. K., et al. "Observation of the effect of gravity on the motion of antimatter." Nature 621.7980 (2023): 716-722.