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1.
Composition at the “ankle” measured by the Pierre Auger Observatory: pure or mixed?
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Alexey Yushkov, 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.
Found in: ključnih besedah
Summary of found: ...ultra-high energy cosmic rays, elemental composition, depth of shower maximum, secondary cosmic rays, Pierre Auger...
Keywords: ultra-high energy cosmic rays, elemental composition, depth of shower maximum, secondary cosmic rays, Pierre Auger Observatory
Published: 02.03.2016; Views: 1990; Downloads: 161
.pdf Fulltext (388,00 KB)

2.
Update of the neutrino and photon limits from the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Carla Bleve, 2015, published scientific conference contribution

Abstract: Ultra-high energy neutrinos and photons, with energies above 1 EeV and 10 EeV respectively, can be detected with the Surface Detector array (SD) of the Pierre Auger Observatory. Downward- going neutrinos of all flavours interacting in the atmosphere at zenith angles θ > 60◦, upward-going tau neutrinos (“Earth- skimming”), as well as photons in the zenith range 30◦ − 60◦ can be identified through the broad time-structure of the signals expected to be induced in the SD stations. An additional signature for photon-induced air showers is the steeper lateral distribution of secondary particles at ground with respect to the nucleonic showers. Stringent limits are set to the diffuse flux of ultra-high energy (UHE) neutrinos and photons, using data collected between 2004 and mid-2013, under the hypothesis of an E[sup]−2 spectrum for signal primaries.
Found in: ključnih besedah
Summary of found: ...ultra-high energy neutrinos, ultra-high energy photons, cosmic rays, elemental composition, Pierre Auger Observatory...
Keywords: ultra-high energy neutrinos, ultra-high energy photons, cosmic rays, elemental composition, Pierre Auger Observatory
Published: 03.03.2016; Views: 1824; Downloads: 152
.pdf Fulltext (398,21 KB)

3.
Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Andrea Di Matteo, 2015, published scientific conference contribution

Abstract: We present a combined fit of both flux and composition of ultra-high energy cosmic rays as measured by the Pierre Auger Observatory. The fit has been performed for energies above 5 × 10[sup]18 eV, i.e. the region of the all-particle spectrum above the so-called “ankle” feature. A simple astrophysical model consisting of identical sources has been adopted, where nuclei are injected with a rigidity dependent mechanism and the sources are uniformly distributed in a comoving volume. The fit results suggest a source model characterized by relatively low maximum injection energies and hard spectral indices. The impact of different sources of systematic uncertainties in the above result is discussed.
Found in: ključnih besedah
Summary of found: ...Pierre Auger Observatory, ultra-high energy cosmic rays, energy spectrum, elemental composition, combined data fit...
Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays, energy spectrum, elemental composition, combined data fit
Published: 03.03.2016; Views: 1849; Downloads: 158
.pdf Fulltext (704,98 KB)

4.
Upgrade of the Pierre Auger Observatory (AugerPrime)
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Ralph Engel, 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.
Found in: ključnih besedah
Summary of found: ...Pierre Auger Observatory, ultra-high energy cosmic rays, elemental composition sensitivity, Auger upgrade (AugerPrime), muonic shower component,...
Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays, elemental composition sensitivity, Auger upgrade (AugerPrime), muonic shower component, scintillator detectors
Published: 03.03.2016; Views: 1704; Downloads: 141
.pdf Fulltext (659,02 KB)

5.
Report of the Working Group on the Composition of Ultra-High Energy Cosmic Rays
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Michael Unger, 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.
Found in: ključnih besedah
Summary of found: ...Pierre Auger Observatory, Telescope Array, Ultra-High Energy Cosmic Rays, elemental composition, extensive air showers, the atmospheric depth of...
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: 08.03.2016; Views: 2016; Downloads: 161
.pdf Fulltext (329,86 KB)

6.
Measurement of the energy spectrum of cosmic rays with the Pierre Auger Observatory
Vitor de Souza, Andrej Filipčič, Ahmed Saleh, Samo Stanič, Darko Veberič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2016, published scientific conference contribution

Found in: ključnih besedah
Summary of found: ...Ultra-high energy cosmic rays (UHECR), UHECR elemental composition, Pierre Auger Observatory, extensive air showers (EAS), EAS long...
Keywords: Ultra-high energy cosmic rays (UHECR), UHECR elemental composition, Pierre Auger Observatory, extensive air showers (EAS), EAS longitudinal profiles, depth of shower maximum
Published: 09.11.2016; Views: 1870; Downloads: 0
.pdf Fulltext (2,50 MB)

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