21. Report of the Working Group on the Composition of Ultra-High Energy Cosmic RaysMichael Unger, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: The atmospheric depth, Xmax, at which the particle number of
an air shower reaches its maximum is a good indicator for the
mass of the primary particle. We present a comparison of the
energy evolution of the mean of Xmax as measured by the
Telescope Array and c Collaborations. After
accounting for the different resolutions, acceptances and
analysis strategies of the two experiments, the two results are
found to be in good agreement within systematic uncertainties.
Keywords: Pierre Auger Observatory, Telescope Array, Ultra-High Energy Cosmic Rays, elemental composition, extensive air showers, the atmospheric depth of the air shower maximum
Published in RUNG: 08.03.2016; Views: 5512; Downloads: 238
 Full text (329,86 KB) |
22. Upgrade of the Pierre Auger Observatory (AugerPrime)Ralph Engel, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: The data collected with the Pierre Auger Observatory have led
to a number of surprising discoveries. While a strong
suppression of the particle flux at the highest energies has
been established unambiguously, the dominant physics processes
related to this suppression could not be identified.
Within the energy range covered by fluorescence detector
observations with sufficient statistics, an unexpected change
of the depth of maximum distribution is found. Using LHC-tuned
interaction models these observations can be understood as a
correlated change of the fluxes of different mass groups.
On the other hand, they could also indicate a change of
hadronic interactions above the energy of the ankle.
Complementing the water Cherenkov detectors of the surface
array with scintillator detectors will, mainly through the
determination of the muonic shower component, extend the
composition sensitivity of the Auger Observatory into the flux
suppression region. The upgrade of the Auger Observatory will
allow us to estimate the primary mass of the highest energy
cosmic rays on a shower-by-shower basis. In addition to
measuring the mass composition the upgrade will open the
possibility to search for light primaries at the highest
energies, to perform composition-selected anisotropy studies,
and to search for new phenomena including unexpected changes
of hadronic interactions. After introducing the physics
motivation for upgrading the Auger Observatory the planned
detector upgrade is presented. In the second part
of the contribution the expected performance and improved
physics sensitivity of the upgraded Auger Observatory are
discussed.
Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays, elemental composition sensitivity, Auger upgrade (AugerPrime), muonic shower component, scintillator detectors
Published in RUNG: 03.03.2016; Views: 5304; Downloads: 226
Full text (659,02 KB) |
23. Measurement of the average electromagnetic longitudinal shower profile at the Pierre Auger ObservatoryFrancisco Diogo, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: In addition to the standard Xmax and energy, the longitudinal
profiles of extensive air showers contain some more interesting
information. For energies above 10[sup]17.8 eV, we present the
average profiles as a function of atmospheric depth measured
for the first time at the Pierre Auger Observatory. The profile
shapes for different energy ranges are all well reproduced by a
Gaisser-Hillas function within the range studied. A detailed
analysis of the systematic uncertainties is performed using
data and a full detector simulation, and the results are
compared with predictions of hadronic interaction models for different primaries.
Keywords: Pierre Auger Observatory, extensive air showers, longitudinal shower profile, Gaisser-Hillas finction
Published in RUNG: 03.03.2016; Views: 5112; Downloads: 191
Full text (684,20 KB) |
24. Measurements of Xmax above 10[sup]17 eV with the fluorescence detector of the Pierre Auger ObservatoryAlessio Porcelli, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: For the first time the Pierre Auger Collaboration
presents〈Xmax〉and σ(Xmax) measurements covering nearly three decades of energy. In this analysis we include
new Xmax data obtained with the High Elevation Auger
Telescopes (HEAT) enhancement. The HEAT telescopes cover
a field of view ranging from 30◦ to 60◦ of elevation and are
located next to one of the standard fluorescence detector sites
(Coihueco). The combination of the HEAT and Coihueco telescopes
covers a field of view from ∼2◦ up to ∼60◦ of elevation. Thus,
the combination can sample the longitudinal profile of nearby
lower energy showers, allowing us to extend the energy range
down to 10[sup]17 eV.
Keywords: extensive atmospheric showers, longitudinal shower profile, depth of the shower maximum, Pierre Auger Observatory
Published in RUNG: 03.03.2016; Views: 6188; Downloads: 239
Full text (718,30 KB) |
25. Composition at the “ankle” measured by the Pierre Auger Observatory: pure or mixed?Alexey Yushkov, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, published scientific conference contribution Abstract: We report for the first time on the measurement of the
correlation between the depth of shower maximum and the signal
in water-Cherenkov stations for events reconstructed by both
the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlated measurement is a unique feature
of a hybrid air-shower observatory and allows us to determine
the purity of the cosmic-ray composition. The observed
correlation in the energy range around the “ankle”
lg(E/eV) = 18.5−19.0 differs significantly from the expectations for pure beams, indicating that the primary composition in this range is mixed, unless the
hadronic interactions at these energies behave very
differently than in conventional, LHC-tuned event generators.
Keywords: ultra-high energy cosmic rays, elemental composition, depth of shower maximum, secondary cosmic rays, Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 6332; Downloads: 244
Full text (388,00 KB) |
