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Title: Muons in air showers at the Pierre Auger Observatory: Mean number in highly inclined events

We present the first hybrid measurement of the average muon number in air showers at ultra-high energies, initiated by cosmic rays with zenith angles between 62° and 80° . Our measurement is based on 174 hybrid events recorded simultaneously with the Surface Detector array and the Fluorescence Detector of the Pierre Auger Observatory. The muon number for each shower is derived by scaling a simulated reference profile of the lateral muon density distribution at the ground until it fits the data. A 10 19 eV shower with a zenith angle of 67°, which arrives at the Surface Detector array at an altitude of 1450 m above sea level, contains on average (2.68 ± 0.04 ± 0.48 (sys.)) × 10 7 muons with energies larger than 0.3 GeV. Finally, the logarithmic gain d ln N µ/d ln E of muons with increasing energy between 4 × 10 18 eV and 5 × 10 19 eV is measured to be (1.029 ± 0.024 ± 0.030 (sys.)).
  1. Univ. of Siegen (Germany). et al.
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1550-7998; arXiv eprint number arXiv:1408.1421
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review. D, Particles, Fields, Gravitation and Cosmology
Additional Journal Information:
Journal Volume: 91; Journal Issue: 05; Journal ID: ISSN 1550-7998
American Physical Society (APS)
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
Pierre AugerCollaboration
Country of Publication:
United States