The main goal of the PUMA [1] (antiProton Unstable Matter Annihilation) experiment is to use antiprotons as a tool to investigate the matter density of short-lived nuclei. For this, antiprotons produced at the Antiproton Decelerator (AD) facility at CERN and decelerated by the Extra Low Energy Antiproton storage ring (ELENA) will be captured, cooled and transported to the ISODLE facility at CERN where the antiprotons will be mixed with short lived isotopes. During this process, an antiproton can be captured by the nucleus and will subsequently annihilate with a neutron or a proton at the surface of the nucleus itself. The pionic fingerprint of this annihilation will be measured using a time-projection-chamber. With this knowledge, the ratio of protons to neutrons on the outermost part of the nuclei distribution can be determined and phenomena like neutron or proton halos or neutron or proton skins can be investigated.
An overview of the PUMA experiment will be given, the current status will be discussed and some of the main physics goals will be highlighted.
[1] Aumann et al., Eur. Phys. J. A (2022) 58: 88