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arXiv · 2204.06662

Cosmic ray spectrum of protons plus helium nuclei between 6 TeV and 158 TeV from HAWC data

HAWC Collaboration·A. Albert·R. Alfaro·C. Alvarez·J. R. Angeles Camacho·J. C. Arteaga-Velázquez·K. P. Arunbabu·D. Avila Rojas·H. A. Ayala Solares·E. Belmont-Moreno·C. Brisbois·K. S. Caballero-Mora·T. Capistrán·A. Carramiñana·S. Casanova·U. Cotti·J. Cotzomi·E. De la Fuente·R. Diaz Hernandez·M. A. DuVernois·M. Durocher·J. C. Díaz-Vélez·C. Espinoza·N. Fraija·J. A. García-González·F. Garfias·M. M. González·J. A. Goodman·J. P. Harding·B. Hona·D. Huang·F. Hueyotl-Zahuantitla·P. Hüntemeyer·A. Iriarte·V. Joshi·D. Kieda·G. J. Kunde·A. Lara·W. H. Lee·H. León Vargas·J. T. Linnemann·A. L. Longinotti·G. Luis-Raya·K. Malone·O. Martinez·J. Martínez-Castro·J. A. Matthews·P. Miranda-Romagnoli·J. A. Morales-Soto·E. Moreno·M. Mostafá·A. Nayerhoda·L. Nellen·M. Newbold·R. Noriega-Papaqui·N. Omodei·E. G. Pérez-Pérez·C. D. Rho·D. Rosa-González·H. Salazar·F. Salesa Greus·A. Sandoval·J. Serna-Franco·A. J. Smith·R. W. Springer·K. Tollefson·I. Torres·R. Torres-Escobedo·F. Ureña-Mena·L. Villaseñor·X. Wang·E. Willox·H. Zhou·C. de León·J. D. Álvarez·G. B. Yodh·A. Zepeda
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Abstract

A measurement with high statistics of the differential energy spectrum of light elements in cosmic rays, in particular, of primary H plus He nuclei, is reported. The spectrum is presented in the energy range from $6$ to $158$ TeV per nucleus. Data was collected with the High Altitude Water Cherenkov (HAWC) Observatory between June 2015 and June 2019. The analysis was based on a Bayesian unfolding procedure, which was applied on a subsample of vertical HAWC data that was enriched to $82\%$ of events induced by light nuclei. To achieve the mass separation, a cut on the lateral age of air shower data was set guided by predictions of CORSIKA/QGSJET-II-04 simulations. The measured spectrum is consistent with a broken power-law spectrum and shows a kneelike feature at around $E = 24.0^{+3.6}_{-3.1} $ TeV, with a spectral index $\gamma = -2.51 \pm 0.02$ before the break and with $\gamma = -2.83 \pm 0.02$ above it. The feature has a statistical significance of $4.1 \, \sigma$. Within systematic uncertainties, the significance of the spectral break is $0.8 \, \sigma$.

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HAWC Collaboration, A. Albert, R. Alfaro, C. Alvarez, J. R. Angeles Camacho, J. C. Arteaga-Velázquez, K. P. Arunbabu, D. Avila Rojas, H. A. Ayala Solares, E. Belmont-Moreno, C. Brisbois, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, J. Cotzomi, E. De la Fuente, R. Diaz Hernandez, M. A. DuVernois, M. Durocher, J. C. Díaz-Vélez, C. Espinoza, N. Fraija, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, J. P. Harding, B. Hona, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, V. Joshi, D. Kieda, G. J. Kunde, A. Lara, W. H. Lee, H. León Vargas, J. T. Linnemann, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Morales-Soto, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, R. Noriega-Papaqui, N. Omodei, E. G. Pérez-Pérez, C. D. Rho, D. Rosa-González, H. Salazar, F. Salesa Greus, A. Sandoval, J. Serna-Franco, A. J. Smith, R. W. Springer, K. Tollefson, I. Torres, R. Torres-Escobedo, F. Ureña-Mena, L. Villaseñor, X. Wang, E. Willox, H. Zhou, C. de León, J. D. Álvarez, G. B. Yodh, A. Zepeda. 2022-04-13. Cosmic ray spectrum of protons plus helium nuclei between 6 TeV and 158 TeV from HAWC data. https://doi.org/10.1103/physrevd.105.063021

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