Abstract
We report a measurement of the energy spectrum of cosmic rays for energies above based on 215,030 events recorded with zenith angles below 60°. A key feature of the work is that the estimates of the energies are independent of assumptions about the unknown hadronic physics or of the primary mass composition. The measurement is the most precise made hitherto with the accumulated exposure being so large that the measurements of the flux are dominated by systematic uncertainties except at energies above . The principal conclusions are
(1) The flattening of the spectrum near , the so-called “ankle,” is confirmed.
(2) The steepening of the spectrum at around is confirmed.
(3) A new feature has been identified in the spectrum: in the region above the ankle the spectral index of the particle flux () changes from to before changing sharply to above .
(4) No evidence for any dependence of the spectrum on declination has been found other than a mild excess from the Southern Hemisphere that is consistent with the anisotropy observed above .
9 More- Received 20 May 2020
- Accepted 30 July 2020
DOI:https://doi.org/10.1103/PhysRevD.102.062005
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
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