The Pierre Auger Observatory was built to give a major contribution to the understanding of ultra-high energy cosmic rays, their origin and nature, as well as to study particle interactions at such high energies. Today, nearly 500 physicists from more than 90 institutions in 16 countries are part of the Collaboration. The Observatory, located in Argentina, is taking data since 2004 and construction was completed in 2008. It is a hybrid detector combining a surface detector array (SD) with a set of fluorescence detector telescopes (FD) watching the atmosphere above it. The SD covers an effective area of 3000 km2 with water Cherenkov tanks. In 2008-2014, the Collaboration published 50 papers which had already more than 5800 citations, including 6 papers ranked among the most cited in Physics Review Letters, Astroparticle Physics journal and Nuclear Instruments and Methods The data taken by Auger have led to a number of breakthroughs in ultra-high energy cosmic ray physics. A suppression of the cosmic ray flux above 5.5x10^19 eV is firmly established, and there are indications for an anisotropic distribution of the arrival direction of the highest energy particles. The cosmic ray composition at very high energies has been addressed and is usually interpreted as an unexpected transition from proton to heavier elements above 3x10^18 eV. The results are however compatible both with the presence of different primary particle types and with a drastic change in hadronic interactions at very high energies. The proton-air cross-section at a center-of-mass energy of 57 TeV has been measured. Strong limits on photon and neutrino fluxes rule out most models for cosmic ray production from relic particle decay. Auger is presently the world’s largest cosmic ray detector and provided impressive results. Nevertheless, puzzles and open questions remain. The main objectives for the next years can be summarized as: 1) Elucidate the origin of the flux suppression and mass composition at the highest energies; 2) Search for a flux contribution of protons up to the highest energies, aiming to reach sensitivity to a contribution as small as 10%; 3) Study extensive air showers and hadronic multi-particle production, aiming at the exploration of fundamental particle physics at energies well beyond those accessible at terrestrial accelerators. The physics implications are profound and the Observatory will remain for many years a unique place to explore them. In order to fully answer these scientific questions, the Auger Collaboration aims at an upgrade of the Observatory. This is cost and schedule effective, and will provide key knowledge on cosmic rays, as well as important know-how for the planning of future experiments. Auger proposes, namely, an enhancement of the muon identification capabilities in the surface array. The LIP Auger group owns a deep know-how in air shower physics and has a clear and unique view on the possible developments for future detectors. The group is mainly focused on the full exploitation of the particle physics potential of the Observatory, namely in the efforts to understand hadronic interactions at high energies through a window that is largely complementary to the LHC. In fact, the group holds unique, world reference competences in specific domains. On the detector development side the group has: strong competences in simulation, in particular GEANT4, being ready to participate in its future developments; RPC development and production facilities at LIP-Coimbra, with a team that is a world reference on RPCs, and a strong know-how on their application to cosmic ray experiments; A fast electronics lab at LIP-Lisbon, devoted to the development of digital data acquisition systems and to the setting up of prototype cosmic ray detection setups. The LIP team is relatively large both in number of members and in competences. While the bulk of the team is in Lisbon, it relies on a close collaboration between the three LIP poles, with the involvement of the Coimbra RPC team and of the Minho analysis team. In conclusion, the LIP cosmic ray group has unique conditions to play a world leading role in R&D in cosmic rays physics analysis in Auger. The group is also an excellent platform for academic training and knowledge dissemination.

Photos

Site do Grupo no LIP

Contacts

Group Leader:  

Pedro Assis

pedjor@lip.pt