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Department of Physics


We report a measurement of the energy spectrum of cosmic rays above 2.5×1018  eV based on 215 030 events. New results are presented: at about 1.3×1019  eV, the spectral index changes from 2.51±0.03(stat)±0.05(syst) to 3.05±0.05(stat)±0.10(syst), evolving to 5.1±0.3(stat)±0.1(syst) beyond 5×1019  eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above 5×1018  eV is [5.66±0.03(stat)±1.40(syst)]×1053  erg Mpc−3.

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Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


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