1. Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showersDanilo Zavrtanik, Marko Zavrtanik, Lili Yang, Serguei Vorobiov, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, Marta Trini, Ahmed Saleh, A. Aab, 2015, original scientific article Found in: osebi Keywords: kozmični žarki ekstremnih energij, AERA, GPS, metoda svetilnik Published: 15.02.2016; Views: 4449; Downloads: 0
Fulltext (5,82 MB) |
2. Prototype muon detectors for the AMIGA component of the Pierre Auger ObservatoryDanilo Zavrtanik, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Marko Zavrtanik, A. Aab, 2015, original scientific article Found in: osebi Keywords: detektor mionov, detektor Čerenkova, AMIGA, P. Auger Observatory Published: 29.02.2016; Views: 4406; Downloads: 0
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3. 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, original scientific article Abstract: 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. Found in: osebi Keywords: ultra-high energy cosmic rays (UHECR), UHECR mass composition, Pierre Auger Observatory, extensive air showers, Auger Surface Detector signals risetime, azimuthal symmetry Published: 15.04.2016; Views: 4478; Downloads: 0
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4. Study of heliospheric effects on galactic cosmic ray fluxes near Earth using low energy modes of the Pierre Auger ObservatoryAhmed Saleh, 2016, published scientific conference contribution abstract Abstract: Surface detector array (SD) of the Pierre Auger Observatory has the capability to observe variations in the flux of low energy secondary cosmic ray particles. Flux rates of low energy particles can be obtained either from particle count rates (scaler mode) or from charge distribution of the pulses (histogram mode), detected by individual water Cherenkov detectors (WCD). In scaler mode, SD is sensitive to particles that deposit energy between ∼15 MeV and ∼100 MeV in a WCD, while in histogram mode the deposited energy range can be extended up to ∼1 GeV. These two low energy detection modes are excellent tools for monitoring modulations of the galactic cosmic ray flux, related to solar activity, such as Forbush decreases (with typical duration of several hours to weeks) and Solar cycle (with a duration of several years), as they provide fluxes of cosmic rays with different energies at the same detector. In this contribution we present an analysis of the effects of space weather and space climate on low energy mode data collected by the Pierre Auger Observatory in the period between 2006 and 2013. In particular, we focus on the long term trend of the cosmic ray flux. In addition to the standard corrections for atmospheric effects such as pressure, the analysis takes into account also the corrections for the long term evolution of the response of the surface detectors. Results show good correlation of the corrected low energy mode Auger data with neutron flux measurements by the global neutron monitoring network (NMDB). Found in: osebi Keywords: Pierre Auger Observatory, Auger low-energy modes, Solar modulation Published: 13.06.2017; Views: 3440; Downloads: 234
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5. First results from the AugerPrime engineering arrayZizhao Zong, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Found in: osebi Keywords: AugerPrime, engineering array, Pierre Auger Observatory Published: 16.02.2018; Views: 2590; Downloads: 149
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6. The flux of ultra-high energy cosmic rays after ten years of operation 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, Inés Valiño, 2015, published scientific conference contribution Abstract: The flux of ultra-high energy cosmic rays has been measured
with unprecedented precision at the Pierre Auger Observatory.
We report an update of the all-sky flux of cosmic rays above 3 x 10 [sup] 17 eV obtained by combining four
independent data sets. These measurements are based on data
from the surface detector arrays (divided into two sets according to the shower zenith angle), from a nested, denser,
detector array, and hybrid events measured simultaneously with
both the fluorescence detector and the surface detector array.
The spectral features are presented in detail and the
systematic uncertainties are addressed. The huge amount of data
collected to date, with a total exposure exceeding
50,000 km2 sr yr, together with the wide range of sky observed
(in declination from -90[deg] to 45[deg]) also allow us to
measure the energy spectrum from different regions of the sky.
We present the results of the search for a dependence of the
measured flux on the declination of the incoming directions. Found in: osebi Keywords: ultra-high energy cosmic rays
energy spectrum
Pierre Auger Observatory Published: 02.03.2016; Views: 4826; Downloads: 211
Fulltext (755,08 KB) |
7. Arrival directions of the highest-energy cosmic rays detected 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, Julien Aublin, 2015, published scientific conference contribution Abstract: We present the results of a search for small to intermediate
scale anisotropies in the distribution of arrival directions
of ultra-high energy cosmic rays recorded at the Pierre Auger
Observatory. The data set, gathered in ten years of operation,
includes arrival directions with zenith angles up to 80◦,
and is about three times larger than that used in earlier
studies. We update the test based on correlations with active
galactic nuclei (AGNs) from the Véron-Cetty and Véron catalog,
which does not yield a significant indication of anisotropy
with the present data set. We perform a blind search for
localized excess fluxes and for self-clustering of arrival
directions at angular scales up to 30◦ and for different
energy thresholds between 40 EeV and 80 EeV. We also examine
the correlation of arrival directions with relatively nearby galaxies in the 2MRS catalog, AGNs detected by Swift-BAT,
and a sample of radio galaxies with jets and with the
Centaurus A galaxy. None of the searches shows a statistically
significant evidence of anisotropy. The two largest
departures from isotropy that were found have a post-trial
probability ≈ 1.4%. One is for cosmic rays with energy above
58 EeV that arrive within 15◦ of the direction toward
Centaurus A. The other is for arrival directions within 18◦
of Swift-BAT AGNs closer than 130 Mpc and brighter than
10[sup]44 erg/s, with the same energy threshold. Found in: osebi Keywords: ultra-high energy cosmic rays
anisotropy studies
active galactic nuclei
Pierre Auger Observatory Published: 02.03.2016; Views: 4271; Downloads: 217
Fulltext (1,32 MB) |
8. Indications of anisotropy at large angular scales in the arrival directions of cosmic rays detected 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, Imen Al Samarai, 2015, published scientific conference contribution Abstract: The large-scale distribution of arrival directions of
high-energy cosmic rays carries major clues to understanding
their origin. The Pierre Auger Collaboration have implemented
different analyses to search for dipolar and quadrupolar
anisotropies in different energy ranges spanning four orders
of magnitude. A common phase ≈270◦ of the first harmonic
modulation in right-ascension was found in adjacent energy intervals below 1 EeV, and another common phase ≈100◦
above 4 EeV. A constancy of phase measurements in ordered
energy intervals originating from a genuine anisotropy is
expected to appear with a smaller number of events than those
needed to achieve significant amplitudes. This led us to
design a prescribed test aimed at establishing whether
this consistency in phases is real at 99% CL. The test required
a total independent exposure of 21,000 km2 sr yr. We report on
the status of this prescription. We also report the results of
the search for a dipole anisotropy for cosmic rays with
energies above 4 EeV using events with zenith angles between
60◦ and 80◦. Compared to previous analyses of events with
zenith angles smaller than 60◦, this extension increases
the size of the data set by 30%, and enlarges the fraction of
exposed sky from 71% to 85%. The largest departure from
isotropy is found in the energy range above 8 EeV, with an
amplitude for the first harmonic in right ascension
r1 = (4.4 ± 1.0) × 10[sup]−2, that has a chance probability
P(≥ r1) = 6.4×10[sup]−5, reinforcing the hint previously
reported with vertical events alone. Found in: osebi Keywords: high-energy cosmic rays
large-scale distribution
anisotropy studies
Pierre Auger Observatory Published: 02.03.2016; Views: 4173; Downloads: 223
Fulltext (862,90 KB) |
9. Search for energy dependent patterns in the arrival direction of cosmic rays 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, Tobias Winchen, 2015, published scientific conference contribution Abstract: Energy-dependent patterns in the arrival directions of cosmic
rays are expected from deflections in galactic and extragalactic magnetic fields. We report on searches for such
patterns in the data of the surface detector of the Pierre
Auger Observatory at energies above E = 5 EeV in regions
within approximately 15◦ around events with energy E > 60
EeV. No significant patterns are found with this analysis which
can be used to constrain parameters in propagation scenarios. Found in: osebi Keywords: ultra-high energy cosmic rays
galactic and extragalactic magnetic fields
magnetic deflection patterns
Pierre Auger Observatory Published: 02.03.2016; Views: 4141; Downloads: 215
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10. Measurements of Xmax above 10[sup]17 eV with the fluorescence detector 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, Alessio Porcelli, 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. Found in: osebi Keywords: extensive atmospheric showers, longitudinal shower profile, depth of the shower maximum, Pierre Auger Observatory Published: 03.03.2016; Views: 4398; Downloads: 221
Fulltext (718,30 KB) |