PUMA (antiProton Unstable Matter Annihilation) is a CERN experiment to investigate the neutron-to-proton densities at the nuclear surface for the most exotic nuclei that can be produced today. It aims at evidencing and at characterizing neutron halos and skins in medium and heavy mass nuclei. PUMA explores a new way to study radioactive nuclei produced at very low kinetic energy: the interaction of antiprotons with unstable nuclei. This approach has never been developed anywhere thus far.
PUMA is based on a new apparatus: a transportable electromagnetic trap to store antiprotons and capture them on short-lived isotopes in order to trigger annihilations and measure the resulting radiations. The PUMA methodology involves two steps. (i) The storage of antiprotons will be performed at the new AD/ELENA facility of CERN in collaboration with the GBAR collaboration. (ii) The stored antiprotons will be transported to CERN/ISOLDE where the PUMA experiment will be conducted.
The project began in January 2018, the experiment was accepted in 2021 and the PUMA apparatus is installed at CERN since December 2024. The venture is just starting.
The device is to be built within an international collaboration. Most important parts are the superconducting solenoid, the trap, the ultra-high vacuum cryostat, the tracking detection system and the analysis tools and techniques.
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