Indications of Proton-Dominated Cosmic-Ray Composition above 1.6 EeVAbbasi, R.U. (Avtor)
Lundquist, Jon Paul (Avtor)
Cosmic raysEnergy spectrumTelescope ArrayHybridUltra high energyWe report studies of ultrahigh-energy cosmic-ray composition via analysis of depth of air shower maximum (Xmax), for air shower events collected by the High-Resolution Fly’s Eye (HiRes) observatory. The HiRes data are consistent with a constant elongation rate d⟨Xmax⟩/d[log(E)] of 47.9 ± 6.0 (stat) ± 3.2 (syst) g/cm^2/decade for energies between 1.6 and 63 EeV, and are consistent with a predominantly protonic composition of cosmic rays when interpreted via the QGSJET01 and QGSJET-II high-energy hadronic interaction models. These measurements constrain models in which the galactic-to-extragalactic transition is the cause of the energy spectrum ankle at 4×10^18 eV.20102020-04-27 20:03:23Delo ni kategorizirano5159COBISS_ID: 12843779DOI: 10.1103/PhysRevLett.104.161101NUK URN: URN:SI:UNG:REP:CT0VGQVPsl