431. 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: 5404; Downloads: 236
 Full text (718,30 KB) |
432. 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: 5344; Downloads: 238
Full text (388,00 KB) |
433. Search for energy dependent patterns in the arrival direction of cosmic rays at the Pierre Auger ObservatoryTobias Winchen, 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: 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.
Keywords: ultra-high energy cosmic rays
galactic and extragalactic magnetic fields
magnetic deflection patterns
Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 5411; Downloads: 228
Full text (1019,52 KB) |
434. Indications of anisotropy at large angular scales in the arrival directions of cosmic rays detected at the Pierre Auger ObservatoryImen Al Samarai, 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 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.
Keywords: high-energy cosmic rays
large-scale distribution
anisotropy studies
Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 5250; Downloads: 238
Full text (862,90 KB) |
435. Arrival directions of the highest-energy cosmic rays detected with the Pierre Auger ObservatoryJulien Aublin, 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 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.
Keywords: ultra-high energy cosmic rays
anisotropy studies
active galactic nuclei
Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 5286; Downloads: 231
Full text (1,32 MB) |
436. The flux of ultra-high energy cosmic rays after ten years of operation of the Pierre Auger ObservatoryInés Valiño, 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 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.
Keywords: ultra-high energy cosmic rays
energy spectrum
Pierre Auger Observatory
Published in RUNG: 02.03.2016; Views: 5788; Downloads: 226
Full text (755,08 KB) |
437. Prototype muon detectors for the AMIGA component of the Pierre Auger ObservatoryA. Aab, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, original scientific article Keywords: detektor mionov, detektor Čerenkova, AMIGA, P. Auger Observatory
Published in RUNG: 29.02.2016; Views: 5423; Downloads: 0
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438. Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showersA. Aab, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2015, original scientific article Keywords: kozmični žarki ekstremnih energij, AERA, GPS, metoda svetilnik
Published in RUNG: 15.02.2016; Views: 5577; Downloads: 0
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439. Študij atmosferskih procesov v Vipavski dolini na podlagi razširjanja aerosolovMaruška Mole, Longlong Wang, Asta Gregorič, Klemen Bergant, Luka Drinovec, Griša Močnik, Samo Stanič, Janja Vaupotič, Marko Vučković, 2016, published scientific conference contribution Abstract: Vipavska dolina je geomorfološko dokaj zaprta, kar po eni strani omogoča pojav močne burje, po drugi strani pa ob stabilnih meteoroloških razmererah ugodne pogoje za kopičenje aerosolov znotraj prizemne mejne plasti. Poznavanje dinamike višinske porazdelitve aerosolov s sočasno uporabo prizemnih meritev omogoča raziskave lokalnih emisij aerosolov, transporta aerosolov na daljše razdalje ter značilnih atmosferskih struktur, ki se pojavijo v različnih vremenskih pogojih. Pri meritvah smo uporabili metode daljinskega zaznavanja z lidarjem, ki omogočajo opazovanje časovnega in prostorskega spreminjanja koncentracij aerosolov, ter točkovne meritve, ki omogočajo njihovo prepoznavanje in določanje njihovih lastnosti. Ugotovili smo, da je mogoče lidarske meritve uporabiti za študij vrste atmosferskih procesov in struktur v zelo različnih vremenskih pogojih. Opazili smo manjše konvekcijske strukture znotraj prizemne mejne plasti in gravitacijske valove nad njo. Meritve vsebnosti in lastnosti aerosolov pri tleh kažejo, da se lahko ob stabilnih atmosferskih pogojih v primerih povečanja lokalnih emisij njihove koncentracije hitro povečajo. Dinamiko in strukturo razširjanja aerosolov znotraj Vipavske doline bomo v prihodnje podrobneje raziskali s sočasnim prostorskim pregledovanjem z metodami daljinskega zaznavanja.
Keywords: aerosoli, atmosferski procesi, daljinsko zaznavanje, Vipavska dolina
Published in RUNG: 25.01.2016; Views: 6787; Downloads: 9
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