Por Lorenzo Cazón (LIP / FCUL).
Abstract: Ultra High-Energy Cosmic Rays (UHECR) are the most energetic particles which we can directly measure. They carry information about the most violent regions in the cosmos, and also pose an excellent opportunity to explore particle physics several orders of magnitude above the energies attained by the LHC. In this seminar, I will introduce the physics of UHECR and the open questions about their origin and composition and also those questions related to the propagation through the interstellar space:their interaction with the CMB and magnetic fields. I will also present the largest cosmic ray facility ever (3000 km2) the Pierre Auger Observatory, and its most important physics results.