EPJ Web of Conferences (Jan 2017)

The influence of the atmospheric refractive index on radio Xmax measurements of air showers

  • Corstanje Arthur,
  • Buitink Stijn,
  • Bonardi Antonio,
  • Falcke Heino,
  • Hörandel Jörg R.,
  • Mitra Pragati,
  • Mulrey Katie,
  • Nelles Anna,
  • Rachen Jörg Paul,
  • Rossetto Laura,
  • Schellart Pim,
  • Scholten Olaf,
  • Thoudam Satyendra,
  • Trinh Gia,
  • ter Veen Sander,
  • Winchen Tobias

DOI
https://doi.org/10.1051/epjconf/201713501012
Journal volume & issue
Vol. 135
p. 01012

Abstract

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The refractive index of the atmosphere, which is n ≈ 1:0003 at sea level, varies with altitude and with local temperature, pressure and humidity. When performing radio measurements of air showers, natural variations in n will change the radio lateral intensity distribution, by changing the Cherenkov angle. Using CoREAS simulations, we have evaluated the systematic error on measurements of the shower maximum Xmax due to variations in n. It was found that a 10% increase in refractivity (n – 1) leads to an underestimation of Xmax between 8 and 22 g/cm2 for proton-induced showers at zenith angles from 15 to 45 degrees, respectively.