Annihilation Vertex Reconstruction Algorithm with Single-Layer Timepix4 Detectors

Abstract: A study of antiproton-nucleus annihilations at rest on a variety of thin solid targets using slow extracted antiprotons is being prepared. To detect the charged annihilation products, the experiment will employ seven Timepix4 ASICs coupled to 500 um thick silicon sensors. These will be arranged in a cuboid geometry that covers the majority of the full solid angle around the target, enabling precise tracking of outgoing particles using only one layer of detectors. With these novel chips, the annihilation will be studied by measuring the total multiplicity, energy, and angular distribution of various prongs produced in a number of targets. A 3D reconstruction algorithm for determining the annihilation vertex from particle tracks in the single-plane detectors has been developed using Monte Carlo simulations. This allows for event-by-event reconstruction, making it possible to distinguish antiproton annihilations on the target from those occurring elsewhere. The measurements will also enable a study of possible final state interactions triggered by the primary annihilation mesons, their evolution with the nuclear mass and their branching ratios.