21. Mass composition of ultra-high energy cosmic rays at the Pierre Auger ObservatoryGašper 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. Keywords: astroparticle physics, ultra-high energy cosmic rays, extensive air showers, mass composition, Pierre Auger Observatory, machine learning, multivariate analysis Published in RUNG: 03.04.2019; Views: 4988; Downloads: 186 Full text (17,53 MB) |
22. Studies of the microwave emission of extensive air showers with GIGAS and MIDAS at the Pierre Auger ObservatoryRomain Gaïor, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Keywords: Pierre Auger Observatory, microwave emission of extensive air showers, GIGAS and MIDAS Published in RUNG: 16.02.2018; Views: 3226; Downloads: 167 Full text (5,97 MB) |
23. Recent Results of the Auger Engineering Radio Array (AERA)Ewa M. Holt, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Keywords: Auger Engineering Radio Array (AERA), Pierre Auger Observatory, extensive air showers Published in RUNG: 16.02.2018; Views: 3480; Downloads: 144 Full text (636,40 KB) |
24. The influence of weather effects on the reconstruction of extensive air showers at the Pierre Auger ObservatoryAlan Coleman, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Keywords: Pierre Auger Observatory, weather effects, reconstruction of extensive air showers Published in RUNG: 16.02.2018; Views: 3237; Downloads: 146 Full text (942,34 KB) |
25. Measurements of the depth of maximum muon production and of its fluctuations in extensive air showers above 1.5×10^19 eV at the Pierre Auger ObservatoryManuela Mallamaci, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Keywords: extensive air showers above, depth of maximum muon production, Pierre Auger Observatory Published in RUNG: 16.02.2018; Views: 3111; Downloads: 159 Full text (654,89 KB) |
26. Particle Physics with the Pierre Auger ObservatoryTanguy Pierog, Andrej Filipčič, Samo Stanič, Darko Veberič, Danilo Zavrtanik, Marko Zavrtanik, 2014, published scientific conference contribution Keywords: Pierre Auger Observatory, extensive air showers, hadronic interactions, proton-air inelastic cross-section Published in RUNG: 27.06.2017; Views: 4010; Downloads: 0 This document has many files! More... |
27. Particle physics at the Pierre Auger ObservatoryJan Ebr, Andrej Filipčič, Ahmed Saleh, Samo Stanič, Darko Veberič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2014, published scientific conference contribution Keywords: Pierre Auger Observatory, extensive air showers, hadronic interactions, proton-air cross section Published in RUNG: 20.06.2017; Views: 4562; Downloads: 206 Full text (1,02 MB) |
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29. Muon counting using silicon photomultipliers in the AMIGA detector of the Pierre Auger observatoryA. Aab, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, original scientific article Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays (UHECR), extensive air showers (EAS), EAS muon content, Auger Muons and Infill for the Ground Array (AMIGA), scintillation modules for muon counting, silicon photomultipliers (SiPM) Published in RUNG: 08.03.2017; Views: 4287; Downloads: 1 This document has many files! More... |
30. The Auger Engineering Radio Array and multi-hybrid cosmic ray detectionE. M. Holt, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Darko Veberič, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2016, published scientific conference contribution Keywords: cosmic rays (CR), extensive air showers, EAS radio emission, Pierre Auger Observatory, Auger Engineering Radio Array, multi-hybrid CR detection Published in RUNG: 09.11.2016; Views: 4424; Downloads: 266 Full text (1,98 MB) |