Measurement of the Depth of Maximum of Extensive Air Showers above 1018 eV

THE PIERRE AUGER COLLABORATION.; S. J. SCIUTTO

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Año: 2010 vol. 104 p. 91101 - 91101

0031-9007

We describe the measurement of the depth of maximum, Xmax, of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 1018 eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of 106 +35 -21 g/cm2/decade below 10 18.24 +-0.05 eV, and (24 +- 3) g/cm2/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.below 10 18.24 +-0.05 eV, and (24 +- 3) g/cm2/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.Xmax, of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 1018 eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of 106 +35 -21 g/cm2/decade below 10 18.24 +-0.05 eV, and (24 +- 3) g/cm2/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.below 10 18.24 +-0.05 eV, and (24 +- 3) g/cm2/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.1018 eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of 106 +35 -21 g/cm2/decade below 10 18.24 +-0.05 eV, and (24 +- 3) g/cm2/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.below 10 18.24 +-0.05 eV, and (24 +- 3) g/cm2/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.26 g/cm2. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.