Measurement of charged-particle production in √sNN=9.62 TeV proton-oxygen collisions as a probe of cosmic-ray air showers with the ATLAS detector

This Letter presents a measurement of prompt charged-particle production in proton-oxygen interactions at √sNN=9.62 TeV center-of-mass energy with the ATLAS detector, corresponding to 634 $μ$b⁻¹ of integrated luminosity. A total of 246 million selected events have at least one track with transverse momentum pT> 500 MeV and pseudorapidity $|η|<2.5$. The measured fiducial proton-oxygen cross section is σfid.pO=396 ± 6~(exp.) ± 9~(lumi.)~mb and the extrapolated inelastic proton-air cross section is σᵖ⁺ᵃⁱʳᵢnel. = 406 ± 6~(exp.) ± 9~(lumi.) ± 28~(th.)~mb. Measurements of charged-particle multiplicity, pT, and $η$ distributions are an order-of-magnitude more precise than differences between hadronic-interaction models. These results enable improved modeling of cosmic-ray air showers, which is important for astroparticle physics.