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61.
Observing the sky at extremely high energies with CTA: Status of the GCT project
Marko Zavrtanik, Danilo Zavrtanik, Gabrijela Zaharijas, Lili Yang, Serguei Vorobiov, Samo Stanič, Gašper Kukec Mezek, Christopher Eckner, Helene Sol, 2017, published scientific conference contribution

Found in: ključnih besedah
Keywords: very high energy, CTA, GCT
Published: 16.02.2018; Views: 1729; Downloads: 130
.pdf Fulltext (916,79 KB)

62.
63.
Probing Lorentz symmetry with the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, D. Boncioli, 2017, published scientific conference contribution

Found in: ključnih besedah
Summary of found: ...Pierre Auger Observatory, Lorentz invariance violation, ultra- high energy cosmic rays...
Keywords: Pierre Auger Observatory, Lorentz invariance violation, ultra-high energy cosmic rays
Published: 16.02.2018; Views: 1991; Downloads: 121
.pdf Fulltext (309,46 KB)

64.
Member of the evaluation committee in charge of awarding with the European mention the doctoral thesis of Dr. Ignacio Vegas Azcárate
Serguei Vorobiov, other performed works

Abstract: I cooperated with the Department of Applied Physics III, Faculty of Physics of the Universidad Complutense of Madrid, Spain, as a member of the evaluation committee in charge of awarding with the European mention the doctoral thesis of Dr. Ignacio Vegas Azcárate, entitled “Nanosecond range pulse generators for quality control and diagnosis of Cherenkov telescope cameras”.
Found in: ključnih besedah
Summary of found: ...very- high energy gamma-ray astronomy, imaging atmospheric Cherenkov telescopes (IACTs), ...
Keywords: very-high energy gamma-ray astronomy, imaging atmospheric Cherenkov telescopes (IACTs), IACT camera quality control and diagnostics, nanosecond range pulse generators
Published: 06.03.2018; Views: 2937; Downloads: 0
.pdf Fulltext (86,20 KB)

65.
Multi-Messenger Physics With the Pierre Auger Observatory
Karl-Heinz Kampert, Andrej Filipčič, Gašper Kukec Mezek, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, original scientific article

Found in: ključnih besedah
Summary of found: ...Pierre Auger Observatory, ultra- high energy cosmic rays, photons, neutrinos, protons, multi-messenger...
Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays, photons, neutrinos, protons, multi-messenger physics and astrophysics
Published: 06.05.2019; Views: 1943; Downloads: 81
.pdf Fulltext (2,46 MB)

66.
Mass composition of ultra-high energy cosmic rays at the Pierre Auger Observatory
Gašper Kukec Mezek, 2019, doctoral dissertation

Abstract: Cosmic rays with energies above 10^18 eV, usually referred to as ultra-high energy cosmic rays (UHECR), have been a mystery from the moment they have been discovered. Although we have now more information on their extragalactic origin, their direct sources still remain hidden due to deviations caused by galactic magnetic fields. Another mystery, apart from their production sites, is their nature. Their mass composition, still uncertain at these energies, would give us a better understanding on their production, acceleration, propagation and capacity to produce extensive air showers in the Earth's atmosphere. Mass composition studies of UHECR try to determine their nature from the difference in development of their extensive air showers. In this work, observational parameters from the hybrid detection system of the Pierre Auger Observatory are used in a multivariate analysis to obtain the mass composition of UHECR. The multivariate analysis (MVA) approach combines a number of mass composition sensitive variables and tries to improve the separation between different UHECR particle masses. Simulated distributions of different primary particles are fitted to measured observable distributions in order to determine individual elemental fractions of the composition. When including observables from the surface detector, we find a discrepancy in the estimated mass composition between a mixed simulation sample and the Pierre Auger data. Our analysis results from the Pierre Auger data are to a great degree independent on hadronic interaction models. Although they differ at higher primary masses, the different models are more consistent, when combining fractions of oxygen and iron. Compared to previously published results, the systematic uncertainty from hadronic interaction models is roughly four times smaller. Our analysis reports a predominantly heavy composition of UHECR, with more than a 50% fraction of oxygen and iron at low energies. The composition is then becoming heavier with increasing energy, with a fraction of oxygen and iron above 80% at the highest energies.
Found in: ključnih besedah
Keywords: astroparticle physics, ultra-high energy cosmic rays, extensive air showers, mass composition, Pierre Auger Observatory, machine learning, multivariate analysis
Published: 03.04.2019; Views: 2835; Downloads: 133
.pdf Fulltext (17,53 MB)

67.
Monte Carlo studies for the optimisation of the Cherenkov Telescope Array layout
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Samo Stanič, A. Acharyya, 2019, original scientific article

Found in: ključnih besedah
Summary of found: ...very- high energy gamma-ray astronomy, Cherenkov Telescope Array, array...
Keywords: very-high energy gamma-ray astronomy, Cherenkov Telescope Array, array layout optimisation, Monte Carlo studies
Published: 18.04.2019; Views: 1783; Downloads: 0
.pdf Fulltext (3,46 MB)

68.
Mass composition of cosmic rays with energies from 10^17.2 eV to 10^20 eV using surface and fluorescence detectors of the Pierre Auger Observatory
Gašper Kukec Mezek, 2018, published scientific conference contribution

Abstract: Ultra-high-energy cosmic rays (UHECRs) are highly energetic particles with EeV energies, exceeding the capabilities of man-made colliders. They hold information on extreme astrophysical processes that create them and the medium they traverse on their way towards Earth. However, their mass composition at such energies is still unclear, because data interpretation depends on our choice of high energy hadronic interaction models. With its hybrid detection method, the Pierre Auger Observatory has the possibility to detect extensive air showers with an array of surface water-Cherenkov stations (SD) and fluorescence telescopes (FD). We present recent mass composition results from the Pierre Auger Collaboration using observational parameters from SD and FD measurements. Using the full dataset of the Pierre Auger Observatory, implications on composition can be made for energies above 10^17.2 eV.
Found in: ključnih besedah
Summary of found: ...Ultra- high-energy cosmic rays (UHECRs) are highly energetic particles...
Keywords: astroparticle physics, ultra-high energy cosmic rays, extensive air showers, mass composition, Pierre Auger Observatory, fluorescence telescopes, water-Cherenkov stations
Published: 24.05.2019; Views: 2059; Downloads: 80
.pdf Fulltext (573,00 KB)

69.
Study of Ultra-High Energy Cosmic Ray composition using Telescope Array’s Middle Drum detector and surface array in hybrid mode
Jon Paul Lundquist, R.U. Abbasi, 2015, original scientific article

Abstract: Previous measurements of the composition of Ultra-High Energy Cosmic Rays (UHECRs) made by the High Resolution Fly’s Eye (HiRes) and Pierre Auger Observatory (PAO) are seemingly contradictory, but utilize different detection methods, as HiRes was a stereo detector and PAO is a hybrid detector. The five year Telescope Array (TA) Middle Drum hybrid composition measurement is similar in some, but not all, respects in methodology to PAO, and good agreement is evident between data and a light, largely protonic, composition when comparing the measurements to predictions obtained with the QGSJetII-03 and QGSJet-01c models. These models are also in agreement with previous HiRes stereo measurements, confirming the equivalence of the stereo and hybrid methods. The data is incompatible with a pure iron composition, for all models examined, over the available range of energies. The elongation rate and mean values of are in good agreement with Pierre Auger Observatory data. This analysis is presented using two methods: data cuts using simple geometrical variables and a new pattern recognition technique.
Found in: ključnih besedah
Keywords: Ultra-High Energy Cosmic Rays, Cosmic ray composition, Atmospheric fluorescence, Extensive air shower array, Hybrid, Telescope Array
Published: 24.04.2020; Views: 1692; Downloads: 0
.pdf Fulltext (3,45 MB)

70.
Evidence for Declination Dependence of Ultrahigh Energy Cosmic Ray Spectrum in the Northern Hemisphere
J. P. Lundquist, R.U. Abbasi, 2018, other component parts

Abstract: The energy of the ultrahigh energy spectral cutoff was measured, integrating over the northern hemisphere sky, by the Telescope Array (TA) collaboration, to be 10^19.78±0.06 eV, in agreement with the High Resolution Fly's Eye (HiRes) experiment, whereas the Pierre Auger experiment, integrating over the southern hemisphere sky, measured the cutoff to be at 10^19.62±0.02 eV. An 11% energy scale difference between the TA and Auger does not account for this difference. However, in comparing the spectra of the Telescope Array and Pierre Auger experiments in the band of declination common to both experiments ( −15.7∘<δ<24.8∘ ) we have found agreement in the energy of the spectral cutoff. While the Auger result is essentially unchanged, the TA cutoff energy has changed to 10^19.59±0.06 eV. In this paper we argue that this is an astrophysical effect.
Found in: ključnih besedah
Summary of found: ...The energy of the ultra high energy spectral cutoff was measured, integrating over...
Keywords: Astrophysics, High Energy Astrophysical Phenomena, UHECR, Cosmic Rays, Anisotropy, Energy Spectrum
Published: 27.04.2020; Views: 1631; Downloads: 54
.pdf Fulltext (687,87 KB)

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