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111.
Studies of the mass composition of cosmic rays and proton-proton interaction cross-sections at ultra-high energies with the Pierre Auger Observatory
Olena Tkachenko, 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 work, we present an estimate of the cosmic-ray mass composition from the distributions of the depth of the shower maximum (�max) measured by the fluorescence detector of the Pierre Auger Observatory. We discuss the sensitivity of the mass composition measurements to the uncertainties in the properties of the hadronic interactions, particularly in the predictions of the particle interaction cross-sections. For this purpose, we adjust the fractions of cosmic-ray mass groups to fit the data with �max distributions from air shower simulations. We modify the proton-proton cross-sections at ultra-high energies, and the corresponding air shower simulations with rescaled nucleus-air cross-sections are obtained via Glauber theory. We compare the energydependent composition of ultra-high-energy cosmic rays obtained for the different extrapolations of the proton-proton cross-sections from low-energy accelerator data.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, extensive air shower, hadronic interactions, cross-section, Xmax
Objavljeno v RUNG: 23.01.2024; Ogledov: 276; Prenosov: 5
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112.
The second knee in the cosmic ray spectrum observed with the surface detector of the Pierre Auger Observatory
Gabriel Brichetto Orquera, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The determination of the energy spectrum features with low systematic uncertainty is crucial for interpreting the nature of cosmic rays. In this study, we conducted a measurement of the energy spectrum at the Pierre Auger Observatory using a surface detector with a calorimetric energy scale indirectly set by a fluorescence detector. The surface detector consists of an array of water-Cherenkov detectors that extends over 3000 km^2 with 1500m spacing. Additionally, two nested arrays of the same kind with 750m and 433m spacing were utilized to lower the energy threshold of the measurements. This contribution presents, for the first time, the spectrum measured with the 433m array, which reduces the energy threshold down to 63 PeV, nearly half the energy at which we previously published a steepening using the 750m array. Our measurements include a characterization of the spectral features of the flux steepening around 230 PeV, known as the second-knee. The study benefits from a nearly 100% duty cycle and geometrical exposure. Notably, this is the first simultaneous measurement of the second knee energy and spectral indexes before and after the break, using a surface detector with an energy scale predominantly independent of air shower simulations and assumptions regarding hadronic interaction models.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, hadronic interaction model, water-Cherenkov detectors
Objavljeno v RUNG: 23.01.2024; Ogledov: 258; Prenosov: 4
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113.
The performances of the upgraded surface detector stations of AugerPrime
Fabio Convenga, 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 of the Pierre Auger Observatory is an array of 1,600 stations using a water Cherenkov detector (WCD) for particle detection. The array is undergoing a major upgrade known as AugerPrime that involves adding scintillator surface detectors (SSDs) and radio antennas to the existing WCDs. Each WCD is also equipped with a smaller photomultiplier tube added to the original ones. As part of the upgrade, underground muon detectors are being installed in an area with a higher density of surface detector stations. AugerPrime required the development of new electronics to process the signals from all the new detectors and handle a higher sampling rate, a more precise GPS receiver, an extended dynamic range, higher processing capacity, and improved monitoring systems and memory. The deployment of the SSDs on top of each surface detector station is currently completed together with the deployment of the new electronics. This contribution will present the first data from the upgraded stations, emphasizing the performances of the SSDs and the new electronics.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, extensive air showers, scintillation surface detectors
Objavljeno v RUNG: 23.01.2024; Ogledov: 274; Prenosov: 5
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114.
Radio interferometry applied to air showers recorded by the Auger engineering radio array
H. Schoorlemmer, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: A new radio interferometric technique was recently developed that takes into account time lags caused by the three-dimensional dependency of the refractive index in the atmosphere. It enables us to track the extensive air shower while it propagates through the atmosphere. Using this technique, properties of the air shower can be estimated, like the depth of maximum and the axis of propagation. In order to apply this method, strict constraints on the time-synchronisation between radio antennas in an array must be satisfied. In this contribution, we show that the Auger Engineering Radio Array can meet these timing criteria by operating a time reference beacon. We will show how this enables us to reconstruct air shower properties using the radio interferometric technique.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, Auger engineering radio array, radio interferometry
Objavljeno v RUNG: 23.01.2024; Ogledov: 265; Prenosov: 4
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115.
Measurements of cloud base height and coverage using elastic multiangle lidar scans at the Pierre Auger Observatory
Juan Pallotta, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: Cloud features significantly affect the reconstruction of extensive air showers, and their characterization plays an important role in atmospheric monitoring. A multi-directional characterization of the cloud pattern is provided by a combination of several instruments of the atmospheric monitoring network at the Pierre Auger Observatory (Mendoza Province, Argentina). In this work, we present the results of an analysis of the cloud measurements using data taken from 2007 to 2022 by the elastic lidars positioned in the proximity of the fluorescence detector (FD) sites. These systems provide hourly measurements of cloud coverage and base height above FD. The ansatz of horizontal homogeneity of cloud structures is tested by comparing the hourly measurements of cloud base height and coverage done simultaneously at different lidar locations. These results allow a detailed description of cloud patterns observed above the array throughout the whole period. The variation of cloud parameters is shown and quantitative conclusions about cloud homogeneity across the array of the Pierre Auger Observatory are given.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, surface detectors, fluorescence detectors
Objavljeno v RUNG: 23.01.2024; Ogledov: 282; Prenosov: 6
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116.
Deep-learning-based cosmic-ray mass reconstruction using the water-Cherenkov and scintillation detectors of AugerPrime
Niklas Langner, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: At the highest energies, cosmic rays can be detected only indirectly by the extensive air showers they create upon interaction with the Earth’s atmosphere. While high-statistics measurements of the energy and arrival directions of cosmic rays can be performed with large surface detector arrays like the Pierre Auger Observatory, the determination of the cosmic-ray mass on an event-by-event basis is challenging. Meaningful physical observables in this regard include the depth of maximum of air-shower profiles, which is related to the mean free path of the cosmic ray in the atmosphere and the shower development, as well as the number of muons that rises with the number of nucleons in a cosmic-ray particle. In this contribution, we present an approach to determine both of these observables from combined measurements of water-Cherenkov detectors and scintillation detectors, which are part of the AugerPrime upgrade of the Observatory. To characterize the time-dependent signals of the two detectors both separately as well as in correlation to each other, we apply deep learning techniques. Transformer networks employing the attention mechanism are especially well-suited for this task. We present the utilized network concepts and apply them to simulations to determine the precision of the event-by-event mass reconstruction that can be achieved by the combined measurements of the depth of shower maximum and the number of muons.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, muons, extensive air showers, surface detectors, AugerPrime, deep learning techiniques
Objavljeno v RUNG: 23.01.2024; Ogledov: 259; Prenosov: 7
.pdf Celotno besedilo (2,93 MB)
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117.
AugerPrime implementation in the DAQ systems of the Pierre Auger Observatory
Ricardo Sato, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The AugerPrime upgrade of the Pierre Auger Observatory converts the existing surface detector, consisting of an array of 1660 water-Cherenkov detectors (WCDs), into a multi-hybrid instrument. This upgrade required improved surface detector electronics and acquisition software to accommodate the new detection channels corresponding to the scintillator surface detectors, radio detector antennas, and the underground muon detectors as well as the additional, small area photomultiplier in theWCDs. In this work, we present an overview of the data acquisition software, both at the level of individual detector stations and the central data acquisition system. We highlight the modifications performed to handle the new multi-hybrid data of AugerPrime and cope with surface detector stations with different hardware configurations operating simultaneously in the array during the transition phase.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, DAQ, AugerPrime
Objavljeno v RUNG: 23.01.2024; Ogledov: 271; Prenosov: 6
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118.
Investigating multiple ELVES and halos above strong lightning with the fluorescence detectors of the Pierre Auger Observatory
Roberto Mussa, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: ELVES are being studied since 2013 with the twenty-four FD Telescopes of the Pierre Auger Observatory, in the province of Mendoza (Argentina), the world’s largest facility for the study of ultra-high energy cosmic rays. This study exploits a dedicated trigger and extended readout. Since December 2020, this trigger has been extended to the three High Elevation Auger Telescopes (HEAT), which observe the night sky at elevation angles between 30 and 60 degrees, allowing a study of ELVES from closer lightning. The high time resolution of the Auger telescopes allows us to upgrade reconstruction algorithms and to do detailed studies on multiple ELVES. The origin of multiple elves can be studied by analyzing the time difference and the amplitude ratio between flashes and comparing them with the properties of radio signals detected by the ENTLN lightning network since 2018. A fraction of multi-ELVES can also be interpreted as halos following ELVES. Halos are disc-shaped light transients emitted at 70-80 km altitudes, appearing at the center of the ELVES rings, due to the rearrangement of electric charges at the base of the ionosphere after a strong lightning event.
Ključne besede: ultra-high energy cosmic rays, Pierre Auger Observatory, surface detectors, fluorescence detectors
Objavljeno v RUNG: 23.01.2024; Ogledov: 270; Prenosov: 5
.pdf Celotno besedilo (9,35 MB)
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119.
Auger@TA : an Auger-like surface detector micro-array embedded within the Telescope Array Project
S. Mayotte, 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 (Auger) and the Telescope Array Project (TA) are the two largest ultra-highenergy cosmic ray (UHECR) observatories in the world. One obstacle in pursuing full-sky UHECR physics is the apparent discrepancy in flux measured by the two experiments. This could be due to astrophysical differences as Auger and TA observe the Southern and Northern skies, respectively. However, the scintillation detectors used by TA have very different sensitivity to the various components of extensive air showers than the water-Cherenkov detectors (WCD) used by Auger. The discrepancy could also be due to systematic effects arising from the differing detector designs and reconstruction methods. The primary goal of the Auger@TA working group is to cross-calibrate the approaches of the two observatories using in-situ methods. This is achieved by placing a self-triggering micro-array, which consists of eight Auger surface detector stations, with both WCDs and AugerPrime scintillators, within the TA array. Seven of the WCDs use a 1-PMT prototype configuration and form a hexagon with the Auger spacing of 1.5 km. The eighth station uses a standard 3-PMT Auger WCD, placed with a TA station at the center of the hexagon to form a triplet for high-statistics, low-uncertainty, cross-calibration of instrumentation. Deployment of the micro-array took place between September 2022 and August 2023, with data-taking foreseen by the Fall of 2023. Details on the instrumentation and deployment of the micro-array, as well as its expected performance, trigger efficiencies, and event rate will be presented. First data from individual stations will also be shown.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, Telescope Array, AugerPrime, scintillators, water-Cherenkov detectors
Objavljeno v RUNG: 23.01.2024; Ogledov: 276; Prenosov: 6
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120.
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: 290; Prenosov: 4
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