Speaker
Description
The HAWC Gamma-Ray Observatory is an extensive air-shower detector array located at 4100 m a.s.l. on the slopes of Volcán Sierra Negra at 19°N in the state of Puebla, Mexico. While HAWC is designed to study the sky in gamma-rays between 500 GeV and 100 TeV, it is also sensitive to showers from primary cosmic rays in the TeV to to multi-PeV energy range. We report on the latest measurements of the energy spectrum, mass composition and arrival direction distribution of cosmic rays at energies from TeV’s to 1 PeV. The cosmic-ray energy spectrum measured by HAWC covers a range that includes the part of the energy region dominated by direct experiments up to just below the knee and shows a cut-off in the total spectrum at tens of TeV’s. We have also estimated the energy spectrum for H+He nuclei, including the observation of a softening at around 24 TeV. Unfolding studies in this energy region indicate that this is the result of individual cut-offs in the spectra of H and He, first observed by direct experiments. Our results also indicate the existence of a cut-off between 100 and 300 TeV in the heavy component of cosmic rays and a hardening in the spectra of the light cosmic ray nuclei at around 100 TeV.
