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Opis: The Pierre Auger Observatory, located near the town Malargüe in the province of Mendoza, Argentina, is the largest cosmic-ray detector in existence, covering an area of 3000 sq. km. The upgraded Observatory, in Phase II of operations, consists of a surface array of 1660 stations combining water Cherenkov, scintillator, and radio detectors. A subset of stations also includes underground muon detectors. Additionally, fluorescence detectors located at four sites overlook the array. The science goals for the enhanced Observatory include the measurement of the properties of ultra-high-energy cosmic rays with large statistics and high sensitivity to the primary composition. The Observatory is also sensitive to photons and neutrinos at the highest energies, allowing it to participate in multi-messenger studies. The Auger Offline Framework provides the tools to perform detailed simulations, using the Geant 4 toolkit, of all components of the Observatory and the analysis of both data and simulated events. It proved to have the flexibility needed to evolve during the lifetime of the Observatory, to accommodate new sub-detectors and, recently, changes to the station readout electronics. A new challenge is interfacing the framework with Machine Learning tools for both the development and execution of neural-network-based algorithms. Independent of the framework, CORSIKA 7 is used to simulate particles, fluorescence light, and radio signals produced by air showers. The production of simulations is coordinated centrally to provide standard libraries for analyses and to optimize the use of computing resources. We will describe the evolution and status of the Offline Framework and the tools used to coordinate the simulation efforts. We will also discuss the challenges of the massive simulation efforts and the resources consumed to provide the simulation libraries required by the Collaboration.
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, air-shower simulations, extensive air showers, detector simulations
Objavljeno v RUNG: 29.05.2025; Ogledov: 410; Prenosov: 6
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Opis: This work focuses on estimating the muon density at ground level using simulations and investigating its correlation with the muonic signal recorded by the Water Cherenkov Detectors (WCDs) of the Pierre Auger Observatory. The study is motivated by the need to validate the estimation of the muonic signal in the WCDs. The methodology involves the development of a parameterization for the surface muon density based on simulated muon data from the Underground Muon Detector (UMD) of AugerPrime—an upgrade to the Pierre Auger Observatory. Our results indicate a negligible bias and a resolution better than 40 at energies above 10[sup]17.5 eV. Furthermore, we find a strong positive correlation between the estimated muon density and the simulated muonic signals in the WCDs.
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, extensive air showers, AugerPrime upgrade, muonic air-shower component
Objavljeno v RUNG: 29.05.2025; Ogledov: 355; Prenosov: 7
Celotno besedilo (861,22 KB)
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Opis: To measure the properties of the highest-energy particles in the Universe with unprecedented precision, we have upgraded the Pierre Auger Observatory. A crucial component of this upgrade is the Radio Detector. Radio antennas have been added to all 1660 positions of the surface detector array, covering an area of 3000 sq. km. The antennas detect radio emission, emitted by extensive air showers in the frequency band from 30 to 80 MHz in two polarization directions - one parallel and one perpendicular to the Earth magnetic field. For inclined air showers with zenith angles above 60 degrees, the radio antennas provide a clean measurement of the electromagnetic shower component, while the water-Čerenkov detectors measure the muonic component. Large-scale deployment in the Argentinian Pampa Amarilla started around June 2023 and has been completed in 2024. The deployment is accompanied by extensive calibration efforts both, in the laboratory and in the field. The signal chain is characterized in the laboratory. Galactic radio emission is used as a reference signal and the antenna patterns are verified through in-situ calibrations with a reference antenna. Commissioning of the system is in full progress as well as the analysis of first measured air showers. We present first air showers measured with the largest radio detector for cosmic rays in the world.
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, extensive air showers, surface detectors, Water-Cherenkov detectors, Surface Scintillator detectors
Objavljeno v RUNG: 16.05.2025; Ogledov: 492; Prenosov: 9
Celotno besedilo (7,10 MB)
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Opis: Cosmic ray detectors like the 3000 sq. km surface array of the Pierre Auger Observatory are capable of observing high-energy photons in the range of 10[sup]18 to 10[sup]20 eV if the flux is sufficiently high. However, no clear candidates for ultra-high-energy photons have been identified yet, so simulations must be used to study typical trigger patterns and observables for discriminating photons from hadrons, e.g., with neural networks. Thinning algorithms are applied to keep the computation time and file sizes in a manageable range since the simulation of ultra-high-energy particle showers is computationally expensive. In CORSIKA, particles with energies below a certain fraction of the primary energy, the thinning level, are exposed to thinning. In the case of thinning, only one of the particles emerging from an interaction is tracked. By assigning a corresponding weight, this particle then represents a number of its siblings. However, the weights of particles that originate from electromagnetic interactions can be 100 times larger than for hadronic interactions. In contrast to hadronic showers, where a major part of the signal in a surface detector is produced by muons, photon showers are almost purely electromagnetic. Using simulations of photon-induced showers with two different thinning levels, the influence on different observables used for photon-hadron discrimination is investigated. Effects deriving from both statistical sampling and detector simulations are considered. Possible influences on station-level as well as event-level observables are probed. With this study, we are reassured that the optimal thinning parameters determined for hadron-induced showers are also sufficient for photon-induced showers.
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, extensive air showers, CORSIKA air-shower simulator
Objavljeno v RUNG: 16.05.2025; Ogledov: 427; Prenosov: 6
Celotno besedilo (3,18 MB)
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Opis: The origin of Ultra-High-Energy Cosmic Rays (UHECRs) is one of the biggest mysteries in modern astrophysics. Since UHECRs are deflected by Galactic and extragalactic magnetic fields, their arrival directions do not point to their sources. Previous analyses conducted on the arrival directions of high-energy events (E ≥ 32 EeV) recorded by the Surface Detector of the Pierre Auger Observatory have not shown significant anisotropies. The largest excess found in the first 19 years of data - at the 4.0 sigma level - is in the region around Centaurus A, and it is also the driving force of a correlation of UHECR arrival directions with a catalog of Starburst Galaxies, which is at the 3.8 sigma level. Since UHECRs are mostly nuclei, the lightest ones (least charged) are also the least deflected. While the mass of the events can be estimated better using the Fluorescence Detector of the Pierre Auger Observatory, the Surface Detector provides the necessary statistics needed for astrophysical studies. The introduction of novel mass-estimation techniques, such as machine learning models and an algorithm based on air-shower universality, will help identify high-rigidity events in the Surface Detector data of the Pierre Auger Observatory. With this work, we present how event-per-event mass estimators can help enhance the sensitivity in the search for anisotropies in the arrival directions of UHECRs at small and intermediate angular scales using simulations.
Ključne besede: ultra-high-energy cosmic rays (UHECRs), extensive air showers, Pierre Auger Observatory, UHECR propagation, UHECR arrival directions, UHECR mass composition, Centaurus A radio galaxy, starburst galaxies, air-shower universality
Objavljeno v RUNG: 30.04.2025; Ogledov: 613; Prenosov: 11
Celotno besedilo (2,03 MB)
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