GCOS
The Global Cosmic Ray Observatory
The Global Cosmic-ray Observatory (GCOS) is a planned large-scale facility designed to study ultra-high-energy cosmic particles, including cosmic rays, photons, and neutrinos. Its main objective is to precisely characterize the properties of the most energetic particles in the universe and to pinpoint their mysterious origins. Featuring an aperture that is twenty times larger than current observatories, GCOS aims to begin operations after 2030, coinciding with the gradual phase-out of existing detectors.
Infrastructure and User Services
To probe the fundamental nature and origin of ultrahigh-energy cosmic rays a major leap in the available exposure for detecting air showers is needed. We therefore target a detector design which would allow us to collect the equivalent exposure of the Pierre Auger Observatory of 20 equivalent years within just one year of data taking. This corresponds to an area of 60000 km2. To achieve a full sky coverage, the GCOS will require at least two observational sites strategically placed around the globe, ideally at intermediate geographical latitudes of +/-35 deg. This setup will ensure comprehensive monitoring of cosmic rays from all directions, providing a complete picture of the cosmic-ray sky. The workhorse of the observatory will be its particle detector (PD) consisting of an array of stations that sample the density of electromagnetic particles (electrons, positrons, photons) and muons on the ground. The energy and mass scale of this array will be set by a fluorescence detector (FD) and/or a radio detector (RD).
Examples/description of the type of research
Nature is providing particles at enormous energies, exceeding 10^20 eV -- orders of magnitude beyond the capabilities of human-made facilities like the Large Hadron Collider at CERN. At the highest energies the precise particle types are not yet known, they might be ionised atomic nuclei or even neutrinos or photons. Even for heavy nuclei (e.g. iron nuclei) their Lorentz factors exceed values of 10^9. The existence of such particles imposes immediate, yet to be answered questions: What are the physics processes involved to produce these particles? Are they decay or annihilation products of Dark Matter? If they are accelerated in violent astrophysical environments: How is nature being able to accelerate particles to such energies? What are the sources of the particles? Do we understand the physics of the sources? Is the origin of those particles connected to the recently observed mergers of compact objects -- the gravitational wave sources? The highly-relativistic particles also provide the unique possibility to study (particle) physics at it extremes: Is Lorentz invariance (still) valid under such conditions? How do these particles interact? Are their interactions described by the Standard Model of particle physics? When the energetic particles interact with the atmosphere of the Earth, hadronic interactions can be studied in the extreme kinematic forward region (with pseudorapidities >15).
GCOS, based on the scientific output of existing observatories, such as the Pierre Auger Observatory and the Telescope Array will provide answers to those questions. Main goal is to conduct particle astronomy at the highest energies.
How to access the infrastructure?
Scientists will work at the observatory sites for installation and maintenance with physical access. The scientific work will be derived from data, which will be available from a central data center with remote access.