41. Extension of the measurement of the proton-air cross section with the Pierre Auger ObservatoryRalf Ulrich, 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: With hybrid data of the Pierre Auger Observatory it is possible
to measure the cross section of proton-air collisions at
energies far beyond the reach of the LHC. Since the first
measurement by the Pierre Auger Collaboration the event
statistics has increased significantly. The proton-air
cross section is now estimated in the two energy intervals in
lg(E/eV) from 17.8 to 18 and from 18 to 18.5. These energies
are chosen so that they maximise the available event statistics
and at the same time lie in the region most compatible with a
significant primary proton fraction. Of these data, only the
20% of most proton-like events are considered for the
measurement. Furthermore, with a new generation of hadronic
interaction models which have been tuned to LHC data, the
model-dependent uncertainties of the measurement are re-visited.
Keywords: Pierre Auger Observatory, extensive air showers, proton-air cross section, hadronic interaction models
Published in RUNG: 03.03.2016; Views: 4529; Downloads: 196
 Full text (114,02 KB) |
42. Azimuthal asymmetry in the risetime of the Surface Detector signals of the Pierre Auger ObservatoryIgnacio Minaya, 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 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 sensitive to the mass
composition of cosmic rays above 3 × 10[sup]18 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 with energy, as has been inferred from other studies.
However the absolute values derived for the mass 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 modelling that must
be resolved before the mass composition can be inferred from
(sec θ)max.
Keywords: Pierre Auger Observatory, Surface Detector, risetime of detector signal, azimuthal asymmetry, extensive air showers
Published in RUNG: 03.03.2016; Views: 4718; Downloads: 196
Full text (243,04 KB) |
43. Search for Ultra-relativistic Magnetic Monopoles with the Pierre Auger ObservatoryToshihiro Fujii, 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: Ultra-relativistic magnetic monopoles, possibly a relic of
phase transitions in the early universe, would deposit an
amount of energy comparable to UHECRs in their passage
through the atmosphere, producing highly distinctive air
shower profiles. We have performed a search for
ultra-relativistic magnetic monopoles in the sample of air
showers with profiles measured by the fluorescence detector of
the Pierre Auger Observatory. No candidate was found to satisfy
our selection criteria and we establish upper limits on the
flux of ultra-relativistic magnetic monopoles - the first from
an UHECR detector - improving over previous results by up to an
order of magnitude.
Keywords: ultra-relativistic magnetic monopoles, extensive air showers, Pierre Auger Observatory
Published in RUNG: 03.03.2016; Views: 4629; Downloads: 195
Full text (188,24 KB) |
44. 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: 5341; Downloads: 236
Full text (718,30 KB) |
