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, objavljeni znanstveni prispevek na konferenci Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...us to determine
the purity of the cosmic-ray composition. The observed
correlation in the energy...
Ključne besede: ultra-high energy cosmic rays, elemental composition, depth of shower maximum, secondary cosmic rays, Pierre Auger Observatory
Objavljeno: 02.03.2016; Ogledov: 4505; Prenosov: 233
 Polno besedilo (388,00 KB) |
2. Update of the neutrino and photon limits from the Pierre Auger ObservatoryMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Carla Bleve, 2015, objavljeni znanstveni prispevek na konferenci Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...ultra-high energy neutrinos,
ultra-high energy photons,
cosmic rays, elemental composition,
Pierre Auger Observatory...
Ključne besede: ultra-high energy neutrinos, ultra-high energy photons, cosmic rays, elemental composition, Pierre Auger Observatory
Objavljeno: 03.03.2016; Ogledov: 4069; Prenosov: 223
Polno besedilo (398,21 KB) |
3. Measurement of the muon content in air showers at the Pierre Auger ObservatoryMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Laura Collica, 2015, objavljeni znanstveni prispevek na konferenci Opis: The muon content of extensive air showers is an
observable sensitive to the primary composition and to
the hadronic interaction properties. We present here
different methods which allow us to estimate the muon number
at the ground level and the muon production depth by
exploiting the measurement of the longitudinal, lateral and
temporal distribution of particles in air showers recorded at
the Pierre Auger Observatory. The results, obtained at about
10[sup]19 eV (E[inf]CM ∼ 140 TeV center-of-mass energy for
proton primaries), are compared to the predictions
of LHC-tuned hadronic interaction models with different primary
masses and suggest a deficit in the muon content at the
ground predicted by simulations. The Pierre Auger Observatory
uses water-Cherenkov detectors to measure particle
densities at the ground and therefore has a good
sensitivity to the muon content of air showers. Moreover, due
to its hybrid design, the combination of muon measurements with
other independent mass composition analyses such as Xmax
provides additional constraints on hadronic interaction models.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Pierre Auger Observatory,
ultra-high energy cosmic rays,
muons, mass composition,
hadronic interactions...
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, muons, mass composition, hadronic interactions
Objavljeno: 03.03.2016; Ogledov: 3937; Prenosov: 212
Polno besedilo (298,46 KB) |
4. Combined fit of spectrum and composition data as measured by the Pierre Auger ObservatoryMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Andrea Di Matteo, 2015, objavljeni znanstveni prispevek na konferenci Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...both flux and composition of
ultra-high energy cosmic rays as measured by the Pierre Auger...
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, energy spectrum, elemental composition, combined data fit
Objavljeno: 03.03.2016; Ogledov: 3752; Prenosov: 228
Polno besedilo (704,98 KB) |
5. 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, objavljeni znanstveni prispevek na konferenci Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...the primary mass of the highest energy
cosmic rays on a shower-by-shower basis. In addition... ...of the muonic shower component, extend the
composition sensitivity of the Auger Observatory into the...
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, elemental composition sensitivity, Auger upgrade (AugerPrime), muonic shower component, scintillator detectors
Objavljeno: 03.03.2016; Ogledov: 3645; Prenosov: 217
Polno besedilo (659,02 KB) |
6. Report of the Working Group on the Composition of Ultra-High Energy Cosmic RaysMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Michael Unger, 2015, objavljeni znanstveni prispevek na konferenci Opis: 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.
Najdeno v: ključnih besedah
Ključne besede: Pierre Auger Observatory, Telescope Array, Ultra-High Energy Cosmic Rays, elemental composition, extensive air showers, the atmospheric depth of the air shower maximum
Objavljeno: 08.03.2016; Ogledov: 3871; Prenosov: 232
Polno besedilo (329,86 KB) |
7. Azimuthal asymmetry in the risetime of the surface detector signals of the Pierre Auger ObservatoryMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, A. Aab, 2016, izvirni znanstveni članek Opis: The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable, (secθ)max, sensitive to the mass composition of cosmic rays above 3×1018 eV. By comparing measurements with predictions from shower simulations, we find for both of our adopted models of hadronic physics (QGSJETII-04 and EPOS-LHC) an indication that the mean cosmic-ray mass increases slowly with energy, as has been inferred from other studies. However, the mass estimates are dependent on the shower model and on the range of distance from the shower core selected. Thus the method has uncovered further deficiencies in our understanding of shower modeling that must be resolved before the mass composition can be inferred from (secθ)max.
Najdeno v: ključnih besedah
Povzetek najdenega: ...(secθ)max, sensitive to the mass composition of cosmic rays above 3×1018 eV. By comparing measurements with...
Ključne besede: ultra-high energy cosmic rays (UHECR), UHECR mass composition, Pierre Auger Observatory, extensive air showers, Auger Surface Detector signals risetime, azimuthal symmetry
Objavljeno: 15.04.2016; Ogledov: 4662; Prenosov: 0
Polno besedilo (698,19 KB) |
8. Measurement of the energy spectrum of cosmic rays with the Pierre Auger ObservatoryVitor de Souza, Andrej Filipčič, Ahmed Saleh, Samo Stanič, Darko Veberič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2016, objavljeni znanstveni prispevek na konferenci Najdeno v: ključnih besedah
Povzetek najdenega: ...Ultra-high energy cosmic rays (UHECR),
UHECR elemental composition,
Pierre Auger Observatory,
extensive air showers (EAS),
EAS longitudinal profiles,
d...
Ključne besede: Ultra-high energy cosmic rays (UHECR), UHECR elemental composition, Pierre Auger Observatory, extensive air showers (EAS), EAS longitudinal profiles, depth of shower maximum
Objavljeno: 09.11.2016; Ogledov: 3696; Prenosov: 0
Polno besedilo (2,50 MB) |
9. Measurement of the mass composition of ultra-high energy cosmic rays with the Pierre Auger ObservatoryMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Mariangela Settimo, 2016, objavljeni znanstveni prispevek na konferenci Najdeno v: ključnih besedah
Ključne besede: ultra-high energy cosmic rays (UHECR), Pierre Auger Observatory, UHECR mass composition
Objavljeno: 09.11.2016; Ogledov: 3872; Prenosov: 230
Polno besedilo (1,24 MB) |
10. Report of the Working Group on the Composition of Ultra High Energy Cosmic RaysMarko Zavrtanik, Danilo Zavrtanik, Serguei Vorobiov, Samo Stanič, Ahmed Saleh, Andrej Filipčič, R. Abbasi, 2016, objavljeni znanstveni prispevek na konferenci Najdeno v: ključnih besedah
Ključne besede: ultra-high energy cosmic rays (UHECR), UHECR mass composition, Pierre Auger Observatory, Telescope Array, cross-calibration studies
Objavljeno: 17.11.2016; Ogledov: 4375; Prenosov: 0
Polno besedilo (448,71 KB) |
