Mass composition of cosmic rays with energies from [1017.2]eV to [1020]eV using surface and fluorescence detectors of the Pierre Auger Observatory

Abstract

Ultra-high-energy cosmic rays (UHECRs) are highly energetic particles with []EeV energies, exceeding the capabilities of man-made colliders. They hold information on extreme astrophysical processes that create them and the medium they traverse on their way towards Earth. However, their mass composition at such energies is still unclear, because data interpretation depends on our choice of high energy hadronic interaction models. With its hybrid detection method, the Pierre Auger Observatory has the possibility to detect extensive air showers with an array of surface water-Cherenkov stations (SD) and fluorescence telescopes (FD). We present recent mass composition results from the Pierre Auger Collaboration using observational parameters from SD and FD measurements. Using the full dataset of the Pierre Auger Observatory, implications on composition can be made for energies above [1017.2]eV.