Speaker
Description
The depth of the shower maximum, $X_\mathrm{max}$, as observed with the fluorescence telescopes, is one of the key most sensitive observables for probing the interaction characteristics and primary composition of ultra-high-energy cosmic rays. Nevertheless, the accurate measurement of the interaction cross-section poses a significant challenge due to the inherent limitations of standard analyses, such as the reliance on assumptions about a specific composition, which in turn is determined based on the assumed validity of particular hadronic interaction models. In this contribution, we present a simultaneous estimation of the proton-proton interaction cross-section and primary mass composition using the hybrid data of the Pierre Auger Observatory, thereby avoiding the drawbacks of separate measurements. The preliminary findings suggest that the proton-proton inelastic cross-section inferred at the ultrahigh energies agrees well with the model extrapolations of low-energy accelerator data and the previous measurements, while the determined cosmic-ray composition also confirms earlier estimates.
