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1.
With AugerPrime to the phase II of the Pierre Auger Observatory
Daniele Martello, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: AugerPrime, the upgrade of the Pierre Auger Observatory, is nearing completion and the Observatory is now prepared to collect physics data after the commissioning of the new components. The Pierre Auger Observatory has demonstrated, based on the data collected thus far, the existence of the cutoff in the spectrum with high accuracy. However, the origin of this cutoff remains incompletely understood. The upgraded Observatory is designed to address the unresolved questions regarding the nature of the cosmic ray flux cutoff thanks to its capability to disentangle the muon and electromagnetic components of extensive air showers. Furthermore, the measurement of the muon component at ground level can verify the accuracy of hadronic interaction models currently used. This presentation will provide an overview of the status of the Observatory and the accurate commissioning done before the start of the physics run. Furthermore, we will present the initial data from Phase II data mainly dedicated to proving the continuity of operation of the Observatory from Phase I to Phase II.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, AugerPrime detector upgrade, Pierre Auger data
Objavljeno v RUNG: 24.01.2024; Ogledov: 267; Prenosov: 6
.pdf Celotno besedilo (4,23 MB)
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2.
Measurement of the mass composition of ultra-high-energy cosmic rays at the Pierre Auger Observatory
Eric Mayotte, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: After nearly 20 years of data-taking, the measurements made with the Pierre Auger Observatory represent the largest collection of ultra-high-energy cosmic ray (UHECR) data so far assembled from a single instrument. Exploring this data set led to a deeper understanding of the UHECR flux and many surprises. In particular, studies aiming to investigate and leverage the mass composition of UHECRs have played an important role in empowering discovery. This contribution will present an overview of the analyses of primary mass composition carried out during the first phase of the Observatory. The overview includes analyses derived from measurements made by the surface, fluorescence, and radio detectors covering energies ranging from 0.1 EeV up to 100 EeV. Special attention will be given to recent advances and results to provide a complete picture of UHECR mass composition at the Observatory as it moves to its next phase, AugerPrime. Additionally, specific updates will be given to studies focusing on mass trends from surface detector rise-times, �max dependent anisotropies, and UHECR beam characterization using the correlation between �max and signal amplitudes at the ground.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, AERA, water-Cherenkov detector
Objavljeno v RUNG: 23.01.2024; Ogledov: 207; Prenosov: 4
.pdf Celotno besedilo (1,03 MB)
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3.
Measuring the muon content of inclined air showers using AERA and the water-Cherenkov detector array of the Pierre Auger Observatory
Marvin Gottowik, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: In this proceeding, we present a proof of principle study for estimating the number of muons of inclined air showers proportional to their energy using hybrid radio and particle detection. We use the radiation energy of an air shower to estimate its electromagnetic energy and measure the muon number independently with the water-Cherenkov detector array (WCD) of the Pierre Auger Observatory. We select 32 high-quality events in almost six years of data with electromagnetic energies above 4 EeV to ensure full efficiency for the WCD reconstruction. The muon content in data is found to be compatible with the one for an iron primary as predicted by current-generation hadronic interaction models. This can be interpreted as a deficit of muons in simulations as a lighter mass composition is expected from �max measurements. Such a muon deficit was already observed in previous analyses of the Auger collaboration and is now confirmed for the first time with radio data. Currently, this analysis is limited by low statistics due to the small area of AERA of 17 km^2 and the high energy threshold. We will outline the advantages of using radio detection instead of the Auger Fluorescence Detector in future analyses allowing for high-statistic measurements of the muon content as a function of energy.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, AERA, water-Cherenkov detector
Objavljeno v RUNG: 23.01.2024; Ogledov: 185; Prenosov: 6
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4.
Status and expected performance of the AugerPrime radio detector
Jannis Pawlowsky, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The ongoing AugerPrime upgrade of the Pierre Auger Observatory will yield sensitivity and precision for measuring ultra-high energy (UHE) cosmic rays that are significantly improved over the baseline design. A key part is the installation of the Radio Detector (RD), consisting of loop antennas mounted on top of each of the 1660 water-Cherenkov detectors (WCD). These antennas, with polarizations both parallel and perpendicular to Earth’s magnetic field, are sensitive to inclined air showers and will also improve the sky coverage and exposure of the observatory. Of special interest is the great sensitivity to the electromagnetic component of air showers, yielding new information for the reconstruction of the primary mass, energy and arrival direction. Complementing traditional particle detectors like the WCD, the combination of both yields new opportunities to detect rare primary particles, e.g. UHE photons and neutrinos with a large identification probability. Here we present the status and future prospects of the RD.With mass production and deployment ongoing, we showair shower statistics and reconstructions of the already installed detector stations. We detail the layout and integration of the RD, demonstrating the potential of the observatory including radio measurements and RD triggering, especially to detect air showers with weak particle footprints. We show that the new trigger enables the measurement of events for which traditional particle detectors are less sensitive.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, radio detector, air shower
Objavljeno v RUNG: 23.01.2024; Ogledov: 244; Prenosov: 5
.pdf Celotno besedilo (7,29 MB)
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5.
Depth of maximum of air-shower profiles above ▫$10^{17.8}$▫ eV measured with the fluorescence detector of the Pierre Auger Observatory and mass-composition implications
Thomas Fitoussi, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: After seventeen years of operation, the first phase of measurements at the PierreAuger Observatory finished and the process of upgrading it began. In this work, we present distributions of the depth of air-shower maximum, �max, using profiles measured with the fluorescence detector of the Pierre Auger Observatory. The analysis is based on the Phase I data collected from 01 December 2004 to 31 December 2021. The �max measurements take advantage of an improved evaluation of the vertical aerosol optical depth and reconstruction of the shower profiles. We present the energy dependence of the mean and standard deviation of the �max distributions above 10^(17.8) eV. Both �max moments are corrected for detector effects and interpreted in terms of the mean logarithmic mass and variance of the masses by comparing them to the predictions of post-LHC hadronic interaction models. We corroborate our earlier findings regarding the change of the elongation rate of the mean �max at 10^(18.3) eV with higher significance. We also confirm, with four more years of data compared to the last results presented in 2019, that around the ankle in the cosmic rays spectrum, the proton component gradually disappears and that intermediate mass nuclei dominate the composition at ultra-high energies.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, protons, surface detector
Objavljeno v RUNG: 23.01.2024; Ogledov: 206; Prenosov: 7
.pdf Celotno besedilo (1,16 MB)
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6.
Reconstruction of muon number of air showers with the surface detector of the Pierre Auger Observatory using neural networks
Steffen Traugott Hahn, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: To understand the physics of cosmic rays at the highest energies, it is mandatory to have an accurate knowledge of their mass composition. Since the mass of the primary particles cannot be measured directly, we have to rely on the analysis of mass-sensitive observables to gain insights into this composition. A promising observable for this purpose is the number of muons at the ground relative to that of an air shower induced by a proton primary of the same energy and inclination angle, commonly referred to as the relative muon number �μ. Due to the complexity of shower footprints, the extraction of �μ from measurements is a challenging task and intractable to solve using analytic approaches. We, therefore, reconstruct �μ by exploiting the spatial and temporal information of the signals induced by shower particles using neural networks. Using this data-driven approach permits us to tackle this task without the need of modeling the underlying physics and, simultaneously, gives us insights into the feasibility of such an approach. In this contribution, we summarize the progress of the deep-learning-based approach to estimate �μ using simulated surface detector data of the Pierre Auger Observatory. Instead of using single architecture, we present different network designs verifying that they reach similar results. Moreover, we demonstrate the potential for estimating �μ using the scintillator surface detector of the AugerPrime upgrade.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, AugerPrime, surface detector
Objavljeno v RUNG: 23.01.2024; Ogledov: 204; Prenosov: 5
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7.
Mass composition from 3 EeV to 100 EeV using the depth of the maximum of air-shower profiles estimated with deep learning using surface detector data of the Pierre Auger Observatory
Jonas Glombitza, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: We present a new analysis for estimating the depth of the maximum of air-shower profiles, �max, to investigate the evolution of the ultra-high-energy cosmic ray mass composition from 3 to 100 EeV. We use a recently developed deep-learning-based technique for the reconstruction of �max from the data of the surface detector of the Pierre Auger Observatory. To avoid systematic uncertainties arising from hadronic interaction models in the simulation of surface detector data, we calibrate the new reconstruction technique with observations of the fluorescence detector. Using the novel analysis, we have a 10-fold increase of statistics at � > 5 EeV with respect to fluorescence detector data. We are able, for the first time, to study the evolution of the mean and standard deviation of the �max distributions up to 100 EeV. We find an excellent agreement with fluorescence observations and confirm the increase of the mean logarithmic mass ⟨ln(�)⟩ and a decrease of the �max fluctuations with energy. The �max measurement at the highest — so far inaccessible — energies is consistent with a pure mass composition and a mean logarithmic mass of around ∼ 3 (estimated using the Sibyll 2.3d and the EPOS-LHC hadronic interaction models). Furthermore, with the increase in statistics, we find indications for a structure beyond a constant elongation rate in the evolution of �max.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, surface detector, flourescence detector
Objavljeno v RUNG: 22.01.2024; Ogledov: 225; Prenosov: 6
.pdf Celotno besedilo (992,98 KB)
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8.
Investigations of a novel energy estimator using deep learning for the surface detector of the Pierre Auger Observatory
Fiona Ellwanger, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: Exploring physics at energies beyond the reach of human-built accelerators by studying cosmic rays requires an accurate reconstruction of their energy. At the highest energies, cosmic rays are indirectly measured by observing a shower of secondary particles produced by their interaction in the atmosphere. At the Pierre Auger Observatory, the energy of the primary particle is either reconstructed from measurements of the emitted fluorescence light, produced when secondary particles travel through the atmosphere, or shower particles detected with the surface detector at the ground. The surface detector comprises a triangular grid of water-Cherenkov detectors that measure the shower footprint at the ground level. With deep learning, large simulation data sets can be used to train neural networks for reconstruction purposes. In this work, we present an application of a neural network to estimate the energy of the primary particle from the surface detector data by exploiting the time structure of the particle footprint. When evaluating the precision of the method on air shower simulations, we find the potential to significantly reduce the composition bias compared to methods based on fitting the lateral signal distribution. Furthermore, we investigate possible biases arising from systematic differences between simulations and data.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, surface detector, neural network
Objavljeno v RUNG: 22.01.2024; Ogledov: 205; Prenosov: 4
.pdf Celotno besedilo (1,78 MB)
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9.
Status and performance of the underground muon detector of the Pierre Auger Observatory
Joaquín De Jesús, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The Pierre Auger Observatory, located in Malargüe, Argentina, is the largest facility for the detection of ultra-high-energy cosmic rays and has been operating successfully for nearly 20 years. For its second phase of operation, the Observatory is undergoing a major upgrade, called AugerPrime, to increase its sensitivity to the primary mass. As part of the upgrade, the Underground Muon Detector is being deployed in the low-energy extension of the Surface Detector. It consists of an array of 30 m^2 plastic scintillator muon counters buried 2.3m underground in the vicinity of the water-Cherenkov detectors. This will allow a direct measurement of the muonic component of air showers in the energy range 1016.5 eV to 1019 eV, contributing significantly to the discrimination of the primary mass and to the testing of hadronic interaction models. In this contribution, the deployment status and performance of the Underground Muon Detector are presented.
Ključne besede: surface detector, Pierre Auger Observatory, AugerPrime, underground muon detector
Objavljeno v RUNG: 22.01.2024; Ogledov: 199; Prenosov: 5
.pdf Celotno besedilo (15,44 MB)
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10.
The time evolution of the surface detector of the Pierre Auger Observatory
Orazio Zapparrata, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The surface detector array of the Pierre Auger Observatory, consisting of 1660 water Cherenkov tanks, has been in operation for nearly 20 years. During this long period of data acquisition, ageing effects in the detector response have been observed. The temporal evolution of the signals recorded by the surface detector is mostly compensated by continuous calibration with atmospheric muons; however, effects persist in the signal rise time and in high-level data analysis using neural networks. We have implemented a detailed description of the time evolution of the detector response and of the uptimes of individual stations in GEANT4-based detector simulations. These new simulations reproduce the observed time dependencies in the data. Using air-shower simulations that take into account the evolution of individual stations, we show that the reconstructed energy is stable at the sub-percent level, and its resolution is affected by less than 5% in 15 years. For a few specific stations, the collected light produced by muons has decreased to the point where it is difficult to distinguish it from the electromagnetic background in the calibration histograms. The upgrade of the Observatory with scintillator detectors mitigates this problem: by requiring a coincidence between the water-Cherenkov and scintillator detectors, we can enhance the muon relative contribution to the calibration histogram. We present the impact and performance of this coincidence calibration method.
Ključne besede: surface detector, Pierre Auger Observatory, neural networks, air-shower simulations
Objavljeno v RUNG: 22.01.2024; Ogledov: 231; Prenosov: 4
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