141. 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: 5018; Downloads: 187 Full text (17,53 MB) |
142. Ultra-high energy neutrinos searches with the Pierre Auger ObservatoryMarta Trini, Danilo Zavrtanik, Danilo Zavrtanik, Serguei Vorobiov, Samo Stanič, Gašper Kukec-Mezek, Lukas Zehrer, 2019, published scientific conference contribution Abstract: In the EeV range, neutrinos are expected to be produced by ultra-high energy cosmic rays interactions with the Cosmic Microwave Background during propagation in the Universe. We report on the search for ultra-high energy neutrinos in data collected with the Surface Detector of the Pierre Auger Observatory. The searches are most efficient in the zenith angle range from 60 degrees to 95 degrees with tau neutrinos skimming in the Earth playing dominant role. The present non-detection of UHE neutrinos in the Pierre Auger Observatory excludes the most optimistic scenarios of neutrino production in terms of UHE cosmic rays chemical composition and cosmological evolution of the acceleration sites. We also report on the searches for neutrinos in coincidence with the recent Gravitational Wave events detected by LIGO/Virgo. Keywords: EeV neutrinos, Pierre Auger Observatory, limits Published in RUNG: 26.02.2019; Views: 3832; Downloads: 0 This document has many files! More... |
143. Testing the agreement between the Xmax distributions measured by the Pierre Auger and Telescope Array ObservatoriesV. De Souza, 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 Keywords: Xmax distributions, Pierre Auger Observatory, Telescope Array Published in RUNG: 19.02.2018; Views: 3827; Downloads: 179 Full text (266,09 KB) |
144. Report of the Telescope Array - Pierre Auger Observatory Working Group on Energy SpectrumDmitri Ivanov, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Darko Veberič, Serguei Vorobiov, Marta Trini, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, 2017, published scientific conference contribution Keywords: Telescope Array, Pierre Auger Observatory, Energy Spectrum Published in RUNG: 19.02.2018; Views: 3473; Downloads: 172 Full text (398,98 KB) |
145. Auger at the Telescope Array: toward a direct cross-calibration of surface-detector stationsS. Quinn, 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 Keywords: Telescope Array, Pierre Auger Observatory, direct cross-calibration Published in RUNG: 19.02.2018; Views: 3473; Downloads: 172 Full text (1,76 MB) |
146. Education and public outreach of the Pierre Auger ObservatoryCharles Timmermans, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Darko Veberič, 2017, published scientific conference contribution Keywords: education, public outreach, Pierre Auger Observatory Published in RUNG: 19.02.2018; Views: 3697; Downloads: 116 Full text (14,82 MB) |
147. The FRAM Telescope at the Pierre Auger ObservatoryJiri Blazek, 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 Keywords: F/Photometric Robotic Atmospheric Monitor (FRAM), Pierre Auger Observatory, atmospheric condition Published in RUNG: 19.02.2018; Views: 3465; Downloads: 328 Full text (2,46 MB) |
148. Improvements to aerosol attenuation measurements at the Pierre Auger ObservatoryMax Malacari, 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 Keywords: aerosol attenuation measurements, Pierre Auger Observatory, fluorescence detector Published in RUNG: 19.02.2018; Views: 4913; Downloads: 169 Full text (1,96 MB) |
149. New electronics for the surface detectors of the Pierre Auger ObservatoryT. Suomijärvi, 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 Keywords: surface detectors, Pierre Auger Observatory, electronics Published in RUNG: 19.02.2018; Views: 3426; Downloads: 162 Full text (334,57 KB) |
150. The Pierre Auger Observatory UpgradeDaniele Martello, 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 Keywords: Pierre Auger Observatory, AugerPrime, improved physics sensitivity Published in RUNG: 19.02.2018; Views: 3264; Downloads: 148 Full text (2,79 MB) |