Institute of Experimental and Applied Physics

Antiproton annihilation is a fundamental process that still lacks a precise description. When annihilation occurs within a nucleus, the initially produced pions can trigger various secondary cascade processes - known as Final State Interactions (FSI) - which redistribute energy and momentum among the nucleons. Despite previous extensive experimental and theoretical efforts, existing models remain only partially successful in reproducing all features of these interactions. Antiproton–nucleus reactions at rest are of particular importance for experiments at CERN's Antiproton Decelerator, which carry out atomic physics studies and high-precision tests of fundamental symmetries. In these experiments, antimatter is primarily identified through its annihilation.

In this talk, I will present results from measurements of antiproton–nucleus annihilation at rest, conducted within the ASACUSA experiment. The study employs 150 eV slow-extracted antiprotons, thin solid targets composed of carbon, molybdenum, and gold, and a Timepix3 quad detector. The experimental results are compared with simulations based on Geant4 and FLUKA, with detector response modeling performed using Allpix².

In addition, I will present a new systematic study conducted last year at the AEgIS experiment, aimed at a detailed investigation of charged fragment production in antiproton-induced reactions across different nuclei. A detection system consisting of six Timepix4 detectors arranged in a cube-like geometry was designed, constructed, and successfully operated under vacuum conditions. Preliminary results from the first attempts at three-dimensional annihilation vertex reconstruction with this approach will also be discussed.