Depth of Maximum of Air-Shower Profiles at the Auger Observatory: Measurements at Energies above 10^17.8 eV

GARCIA, B (500 AUTHORS IN ALPHABETICAL ORDER)

PHYSICAL REVIEW D

AMER PHYSICAL SOC

Lugar: New York; Año: 2014 vol. 90 p. 1 - 25

1550-7998

We report a study of the distributions of the depth of maximum, Xmax, of extensive air-shower profileswith energies above 1017.8 eV as observed with the fluorescence telescopes of the Pierre AugerObservatory. The analysis method for selecting a data sample with minimal sampling bias is describedin detail as well as the experimental cross-checks and systematic uncertainties. Furthermore, we discuss thedetector acceptance and the resolution of the Xmax measurement and provide parametrizations thereof as afunction of energy. The energy dependence of the mean and standard deviation of the Xmax distributions arecompared to air-shower simulations for different nuclear primaries and interpreted in terms of the mean andvariance of the logarithmic mass distribution at the top of the atmosphere.