11. 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: ...cosmic-ray composition. The observed
correlation in the energy range around the “ankle”
lg(E/eV) = 18.5−19.0 differs...
Ključne besede: ultra-high energy cosmic rays, elemental composition, depth of shower maximum, secondary cosmic rays, Pierre Auger Observatory
Objavljeno: 02.03.2016; Ogledov: 3463; Prenosov: 202
 Polno besedilo (388,00 KB) |
12. 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 and photons, with energies above
1...
Ključne besede: ultra-high energy neutrinos, ultra-high energy photons, cosmic rays, elemental composition, Pierre Auger Observatory
Objavljeno: 03.03.2016; Ogledov: 3344; Prenosov: 191
Polno besedilo (398,21 KB) |
13. 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: ...
10[sup]19 eV (E[inf]CM ∼ 140 TeV center-of-mass energy for
proton primaries), are compared to the...
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, muons, mass composition, hadronic interactions
Objavljeno: 03.03.2016; Ogledov: 3305; Prenosov: 181
Polno besedilo (298,46 KB) |
14. 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: ...of both flux and composition of
ultra-high energy cosmic rays as measured by the Pierre...
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, energy spectrum, elemental composition, combined data fit
Objavljeno: 03.03.2016; Ogledov: 3124; Prenosov: 199
Polno besedilo (704,98 KB) |
15. 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: ...this suppression could not be identified.
Within the energy range covered by fluorescence detector
observations with...
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: 3004; Prenosov: 184
Polno besedilo (659,02 KB) |
16. The Energy Content of Extensive Air Showers in the Radio Frequency Range of 30-80 MHzMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Christian Glaser, 2015, objavljeni znanstveni prispevek na konferenci Opis: At the Auger Engineering Radio Array (AERA) of the Pierre Auger
Observatory, we have developed a new method to measure the
total amount of energy that is transferred from the primary
cosmic ray into radio emission. We find that this radiation
energy is an estimator of the cosmic ray energy. It scales
quadratically with the cosmic ray energy, as expected for
coherent emission. We measure 15.8 MeV of radiation energy for
a 1 EeV air shower arriving perpendicular to the geomagnetic
field at the Auger site, in the frequency band of the detector
from 30 to 80 MHz. These observations are compared to the data
of the surface detector of the Observatory, which provide
well-calibrated energies and arrival directions of the cosmic
rays. We find energy resolutions of the radio reconstruction
of 22% for the complete data set, and 17% for a high-quality
subset containing only events with at least five stations with
signal.
Najdeno v: ključnih besedah
Ključne besede: Pierre Auger Observatory, the Auger Engineering Radio Array (AERA), extensive air showers, radio reconstruction: energy resolution
Objavljeno: 03.03.2016; Ogledov: 3217; Prenosov: 173
Polno besedilo (574,66 KB) |
17. AugerNext: R&D studies at the Pierre Auger Observatory for a next generation ground-based ultra-high energy cosmic-ray experimentMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Andreas Haungs, 2015, objavljeni znanstveni prispevek na konferenci Opis: The findings so far of the Pierre Auger Observatory and those
of the Telescope Array define some requirements for a possible
next generation global cosmic ray observatory: it needs to be
considerably increased in size, it needs enhanced sensitivity
to composition, and it has to cover the full sky. At the Pierre
Auger Observatory, AugerNext aims to conduct some innovative
initial research studies on a design of a sophisticated hybrid
detector fulfilling these demands. Within a European supported
ASPERA/APPEC (Astroparticle Physics European Consortium)
project for the years 2011-2014, such R&D studies primarily
focused on the following areas: i) consolidation of the
detection of cosmic rays using MHz radio antennas; ii) proof-
of-principle of cosmic ray microwave detection; iii) test of
the large-scale application of new generation photo sensors;
iv) generalization of data communication techniques; and v)
development of new schemes for muon detection with surface
arrays. The AugerNext Consortium consists of 14 principal
investigators from 9 countries. This contribution summarizes
some achievements of the R&D studies within the AugerNext
project.
Najdeno v: ključnih besedah
Ključne besede: ultra-high energy cosmic-ray experiments, Pierre Auger Observatory, Telescope Array, AugerNext research and development study
Objavljeno: 03.03.2016; Ogledov: 3238; Prenosov: 164
Polno besedilo (594,23 KB) |
18. Search for a correlation between the UHECRs measured by the Pierre Auger Observatory and the Telescope Array and the neutrino candidate events from IceCubeMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Asen Christov, 2015, objavljeni znanstveni prispevek na konferenci Opis: We have conducted three searches for correlations between
ultra-high energy cosmic rays detected by the Telescope Array
and the Pierre Auger Observatory, and high-energy neutrino
candidate events from IceCube. Two cross-correlation analyses
with UHECRs are done: one with 39 cascades from the IceCube
‘high-energy starting events’ sample and the other with 16
high-energy ‘track events’. The angular separation between the
arrival directions of neutrinos and UHECRs is scanned over.
The same events are also used in a separate search using a
maximum likelihood approach, after the neutrino arrival
directions are stacked. To estimate the significance we assume
UHECR magnetic deflections to be inversely proportional to
their energy, with values 3◦, 6◦ and 9◦ at 100 EeV to allow for
the uncertainties on the magnetic field strength and UHECR
charge. A similar analysis is performed on stacked UHECR
arrival directions and the IceCube sample of through-going
muon track events which were optimized for neutrino point-
source searches.
Najdeno v: ključnih besedah
Povzetek najdenega: ...conducted three searches for correlations between
ultra-high energy cosmic rays detected by the Telescope Array...
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, Telescope Array, high-energy neutrinos, IceCube, correlation search
Objavljeno: 08.03.2016; Ogledov: 3487; Prenosov: 151
Polno besedilo (1,11 MB) |
19. 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: 3241; Prenosov: 199
Polno besedilo (329,86 KB) |
20. Large-Scale Distribution of Arrival Directions of Cosmic Rays Detected at the Pierre Auger Observatory and the Telescope Array above 10[sup]19 eVMarko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Olivier Deligny, 2015, objavljeni znanstveni prispevek na konferenci Opis: The large-scale distribution of arrival directions of
high-energy cosmic rays is a key observable in attempts to
understanding their origin. The dipole and quadrupole moments
are of special interest in revealing potential anisotropies.
An unambiguous measurement of these moments as well as
of the full set of spherical harmonic coefficients requires
full-sky coverage. This can be achieved by combining data from
observatories located in both the northern and southern
hemispheres. To this end, a joint analysis using data recorded
at the Pierre Auger Observatory and the Telescope Array above
10[sup]19 eV has been performed. Thanks to the full-sky
coverage, the measurement of the dipole moment reported in
this study does not rely on any assumption on the underlying
flux of cosmic rays. As well, the resolution on the quadrupole
and higher order moments is the best ever obtained. The
resulting multipolar expansion of the flux of cosmic rays
allows a series of anisotropy searches to be performed,
and in particular to report on the first angular power
spectrum of cosmic rays. This allows a comprehensive
description of the angular distribution of cosmic rays
above 10[sup]19 eV.
Najdeno v: ključnih besedah
Povzetek najdenega: ...The large-scale distribution of arrival directions of
high- energy cosmic rays is a key observable in...
Ključne besede: Pierre Auger Observatory, Telescope Array, high-energy cosmic rays, large-scale anisotropies, angular power spectrum
Objavljeno: 08.03.2016; Ogledov: 3120; Prenosov: 153
Polno besedilo (462,61 KB) |
