A measurement of the all-particle energy spectrum of cosmic rays from 10¹³ to 10¹⁵eV using HAWC

We report the total energy spectrum of cosmic rays in the energy interval from 10TeV to 1PeV, which lies in the energy region where both direct and indirect cosmic ray experiments overlap. The all-particle spectrum was obtained from an unfolding analysis of 5.3 years of data collected with the High Altitude Water Cherenkov (HAWC) observatory for zenith angles smaller than or equal to 35°. The study was carried out in the framework of the QGSJET-II-04 hadronic interaction model. The measured spectrum confirms the presence of a knee-like feature at tens of TeV. In our analysis, the position of this softening is found at 40.2±1.0(stat.)_−6.4^+6.2(sys.)TeV. The measured spectral indices before and after the break are γ₁=−2.53±0.01(stat.)_−0.05^+0.04(sys.) and γ₂=−2.71±0.01(stat.)_−0.04^+0.03(sys.), respectively.