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91.
Observation of Variations in Cosmic Ray Shower Rates During Thunderstorms and Implications for Large-Scale Electric Field Changes
R. Abbasi, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci

Opis: This work presents the first observation by the Telescope Array Surface Detector (TASD) of the effect of thunderstorms on the development of the cosmic ray showers. Observations of variations in the cosmic ray showers, using the TASD, allows us to study the electric field inside thunderstorms on a large scale without dealing with all the limitation of narrow exposure in time and space using balloons and aircraft detectors. In this work, observations of variations in the cosmic ray shower intensity (ΔN/N) using the TASD, was studied and found to be on average at the (1−2)% level. These observations where found to be both negative and positive in polarity. They were found to be correlated with lightning but also with thunderstorms. The size of the footprint of these variations on the ground ranged from (4-24) km in diameter and lasted for 10s of minutes. Dependence of (ΔN/N) on the electric field inside thunderstorms, in this work, is derived from CORSIKA simulations.
Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, shower profile, lightning, atmospheric electric fields
Objavljeno v RUNG: 04.10.2023; Ogledov: 863; Prenosov: 5
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92.
Mass composition anisotropy with the Telescope Array Surface Detector data
Y. Zhezher, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci

Opis: Mass composition anisotropy is predicted by a number of theories describing sources of ultra-high-energy cosmic rays. Event-by-event determination of a type of a primary cosmic-ray particle is impossible due to large shower-to-shower fluctuations, and the mass composition usually is obtained by averaging over some composition-sensitive observable determined independently for each extensive air shower (EAS) over a large number of events. In the present study we propose to employ the observable ξ used in the TA mass composition analysis for the mass composition anisotropy analysis. The ξ variable is determined with the use of Boosted Decision Trees (BDT) technique trained with the Monte-Carlo sets, and the ξ value is assigned for each event, where ξ=1 corresponds to an event initiated by the primary iron nuclei and ξ=−1 corresponds to a proton event. Use of ξ distributions obtained for the Monte-Carlo sets allows us to separate proton and iron candidate events from a data set with some given accuracy and study its distributions over the observed part of the sky. Results for the TA SD 11-year data set mass composition anisotropy will be presented.
Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, composition, anisotropy, machine learning, boosted decision tree
Objavljeno v RUNG: 04.10.2023; Ogledov: 893; Prenosov: 5
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93.
The measurements of the cosmic ray energy spectrum and the depth of maximum shower development of Telescope Array Hybrid trigger events
H. Shin, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci

Opis: The Telescope Array experiment is an ultra-high energy cosmic ray observatory located in Millard County, Utah, USA. The observatory consists of 3 fluorescence detector (FD) stations and 507 surface detectors (SD) that cover an area of ~700 km^2. Hybrid trigger is an external trigger system for the SD arrays that prompts the SD to perform data acquisition when an FD detects a shower-like event. In comparison with the SD autonomous trigger, hybrid trigger allows the SD to collect the data of an air shower that has primary energy below 10^18.5 eV, where the efficiency of SD autonomous trigger decreases rapidly. We present the measurements of the cosmic ray energy spectrum and the depth of maximum shower development of hybrid trigger events observed from October 2010 to September 2014.
Ključne besede: Telescope Array, indirect detection, hybrid detection, ground array, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, composition
Objavljeno v RUNG: 04.10.2023; Ogledov: 938; Prenosov: 5
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94.
Cosmic-ray mass composition with the TA SD 12-year data
Y. Zhezher, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci

Opis: Telescope Array (TA) is the largest ultra-high-energy cosmic-ray (UHECR) observatory in the Northern Hemisphere. It is dedicated to detect extensive air showers (EAS) in hybrid mode, both by measuring the shower’s longitudinal profile with fluorescence telescopes and their particle footprint on the ground from the surface detector (SD) array. While fluorescence telescopes can measure the most composition-sensitive characteristic of EAS, the depth of the shower maximum (\xmax), they also have the drawback of small duty cycle. This work aims to study the UHECR composition based solely on the surface detector data. For this task, a set of composition-sensitive observables obtained from the SD data is used in a machine-learning method -- the Boosted Decision Trees. We will present the results of the UHECR mass composition based on the 12-year data from the TA SD using this technique, and we will discuss of the possible systematics imposed by the hadronic interaction models.
Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, composition, machine learning, boosted decision tree
Objavljeno v RUNG: 04.10.2023; Ogledov: 892; Prenosov: 7
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95.
The ultra-high-energy cosmic-ray sky above 32 EeV viewed from the Pierre Auger Observatory
J. Biteau, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci

Opis: The region of the toe in the cosmic-ray spectrum, located at about 45 EeV by the Pierre Auger Collaboration, is of primary interest in the search for the origin of ultra-high energy cosmic rays (UHECRs). The suppression of the flux with increasing energy can be explained by the interaction of UHECRs with intergalactic photons, resulting in a shrinking of the observable universe, and/or by cut-offs in acceleration potential at the astrophysical sources, yielding a high-rigidity sample of single (or few) UHECR species around the toe. The predominance of foreground sources combined with reduced deflections could thus offer a path towards localizing ultra-high energy accelerators, through the study of UHECR arrival directions. In this contribution, we present the results of blind and astrophysically-motivated searches for anisotropies with data collected above 32 EeV during the first phase of the Pierre Auger Observatory, i.e. prior to the AugerPrime upgrade, for an exposure of over 120,000 km^2 yr sr. We have conducted model-independent searches for overdensities at small and intermediate angular scales, correlation studies with several astrophysical structures, and cross-correlation analyses with catalogs of candidate extragalactic sources. These analyses provide the most important evidence to date for anisotropy in UHECR arrival directions around the toe as measured from a single observatory.
Ključne besede: Pierre Auger Observatory, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, anisotropy, overdensities, hotspot, source correlation, cross-correlation
Objavljeno v RUNG: 04.10.2023; Ogledov: 889; Prenosov: 6
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96.
UHECR arrival directions in the latest data from the original Auger and TA surface detectors and nearby galaxies
A. di Matteo, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci

Opis: The distribution of ultra-high-energy cosmic-ray arrival directions appears to be nearly isotropic except for a dipole moment of order 6×(E/10 EeV) per cent. Nonetheless, at the highest energies, as the number of possible candidate sources within the propagation horizon and the magnetic deflections both shrink, smaller-scale anisotropies might be expected to emerge. On the other hand, the flux suppression reduces the statistics available for searching for such anisotropies. In this work, we consider two different lists of candidate sources: a sample of nearby starburst galaxies and the 2MRS catalog tracing stellar mass within 250 Mpc. We combine surface-detector data collected at the Pierre Auger Observatory until 2020 and the Telescope Array until 2019, and use them to test models in which UHECRs comprise an isotropic background and a foreground originating from the candidate sources and randomly deflected by magnetic fields. The free parameters of these models are the energy threshold, the signal fraction, and the search angular scale. We find a correlation between the arrival directions of 11.8%+5.0%−3.1% of cosmic rays detected with E≥38 EeV by Auger or with E≳49 EeV by TA and the position of nearby starburst galaxies on a 15.5∘+5.3∘−3.2∘ angular scale, with a 4.2σ post-trial significance, as well as a weaker correlation with the overall galaxy distribution.
Ključne besede: Pierre Auger Observatory, Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, anisotropy, full-sky, starburst galaxies, source correlations, dipole
Objavljeno v RUNG: 04.10.2023; Ogledov: 957; Prenosov: 4
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97.
Adjustments to Model Predictions of Depth of Shower Maximum and Signals at Ground Level using Hybrid Events of the Pierre Auger Observatory
J. Vicha, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci

Opis: We present a new method to explore simple ad-hoc adjustments to the predictions of hadronic interaction models to improve their consistency with observed two-dimensional distributions of the depth of shower maximum, Xmax, and signal at ground level, as a function of zenith angle. The method relies on the assumption that the mass composition is the same at all zenith angles, while the atmospheric shower development and attenuation depend on composition in a correlated way. In the present work, for each of the three leading LHC-tuned hadronic interaction models, we allow a global shift ΔXmax of the predicted shower maximum, which is the same for every mass and energy, and a rescaling R_Had of the hadronic component at ground level which depends on the zenith angle. We apply the analysis to 2297 events reconstructed by both fluorescence and surface detectors at the Pierre Auger Observatory with energies 10^18.5−10^19.0 eV. Given the modeling assumptions made in this analysis, the best fit reaches its optimum value when shifting the Xmax predictions of hadronic interaction models to deeper values and increasing the hadronic signal at both extreme zenith angles. The resulting change in the composition towards heavier primaries alleviates the previously identified model deficit in the hadronic signal (commonly called the muon deficit), but does not remove it. Because of the size of the required corrections ΔXmax and R_Had and the large number of events in the sample, the statistical significance of the corrections is large, greater than 5σstat even for the combination of experimental systematic shifts within 1σsys that are the most favorable for the models.
Ključne besede: Pierre Auger Observatory, indirect detection, fluorescence detection, ground array, surface detection, ultra-high energy, cosmic rays, composition, Xmax, muon deficit, air-shower models
Objavljeno v RUNG: 04.10.2023; Ogledov: 963; Prenosov: 6
.pdf Celotno besedilo (1,14 MB)
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98.
STRENGTHENING ENERGY AND CLIMATE LITERACY WITH MICROLEARNING AND OPEN EDUCATIONAL RESOURCES
Mojca Drevenšek, 2023, magistrsko delo

Opis: This master’s thesis is motivated by the desire to actively engage Slovenian youth in co-creating our energy and climate future. The background is the growing interest in effective energy transition at the national, EU and global levels, and we specifically focus on the role of education in achieving this goal. The main problem we address is the need for improvement of energy- and climate-related non-formal youth education to increase their interest in the topic, and motivate their engagement in public discussions and the policy-making processes. To tackle this problem, we use the existing En-ROADS energy and climate interactive simulation tool and the accompanying online training series and complement it with new learning materials and learning activities, developed in our educational project. Our approach focuses on open education practices and the co-creation of open educational resources (OER), supported by microlearning via social media (Instagram). We develop a novel approach to address the problem by involving youth in a non-formal open educational process where they are invited to co-create the content and format of learning materials, decide on the technologies used, and affect the implementational process of the key learning activities. The main contributions of the thesis are the developed OERs, which can be adapted, reused or remixed by other stakeholders in the field of energy and climate education, and the recommendations for educators both in the field of energy and climate topics as well as in other fields, related to education for sustainable development. The main methodological finding of the thesis focuses on the importance of flexibility and adaptation of learning materials and activities according to the expressed interests and expectations of young learners. Their feedback needs to be carefully gathered and integrated into the implementation of the project.
Ključne besede: energy literacy, climate literacy, open education, OER (open educational resources), microlearning, online learning, systems thinking
Objavljeno v RUNG: 03.10.2023; Ogledov: 1646; Prenosov: 25
.pdf Celotno besedilo (3,38 MB)

99.
Combined fit of the energy spectrum and mass composition across the ankle with the data measured at the Pierre Auger Observatory
E. Guido, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci

Opis: The combined fit of the energy spectrum and mass composition data above 5 EeV suggested the presence of extragalactic sources ejecting ultra-high-energy cosmic rays with relatively low maximum energies, hard spectral indices and mixed chemical compositions, dominated by the contribution of intermediate mass groups. Here we present an extension of the fit to lower energies, to include the feature observed near 5 EeV in the all-particle energy spectrum, the so-called ankle. We show that it is possible to generate such a change of slope assuming that the flux below the ankle is provided by the superposition of different contributions. The simplest extension of this sort consists of introducing a supplemental extragalactic component at low energy, characterised by different physical parameters with respect to the one being dominant above the ankle: such a component may originate from a different population of sources or be provided by interactions occurring in the acceleration sites. In this framework we also explore the possibility of including the end of a Galactic contribution at low energies. The fit suggests that these scenarios provide a reasonable description of the measurements across the ankle, without significantly affecting the interpretation obtained for the above-ankle region. In order to evaluate our capability to constrain the source models, we finally discuss the impact of the main experimental systematic uncertainties and of the theoretical models choice on the fit results.
Ključne besede: Pierre Auger Observatory, indirect detection, fluorescence detection, hybrid detection, surface detection, ultra-high energy, cosmic rays, composition, energy spectrum, combined fit
Objavljeno v RUNG: 03.10.2023; Ogledov: 898; Prenosov: 4
.pdf Celotno besedilo (1,09 MB)
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100.
Indication of a mass-dependent anisotropy above 10^18.7 eV in the hybrid data of the Pierre Auger Observatory
E.W. Mayotte, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci

Opis: We test the hypothesis of an anisotropy laying along the galactic plane which depends on the mass of primary cosmic-rays. The sensitivity to primary mass is provided by the depth of shower maximum, Xmax, from hybrid events measured at the Pierre Auger Observatory. The 14 years of available data are split into on- and off-plane regions using the galactic latitude of each event to form two distributions in Xmax, which are compared using the Anderson-Darling 2-samples test. A scan over a subset of the data is used to select an optimal threshold energy of 10^18.7 eV and a galactic latitude splitting at |b|=30∘, which are then set as a prescription for the remaining data. With these thresholds, the distribution of Xmax from the on-plane region is found to have a 9.1±1.6+2.1−2.2 g/cm2 shallower mean and a 5.9±2.1+3.5−2.5 g/cm2 narrower width than that of the off-plane region. These differences are as such to indicate that the mean mass of primary particles arriving from the on-plane region is greater than that of those coming from the off-plane region. Monte-Carlo studies yield a 4.4σ post-penalization statistical significance for the independent data. Including the scanned data results in a 4.9+1.4−1.5σ post-penalization statistical significance, where the uncertainties are of systematic origin. Accounting for systematic uncertainties leads to an indication for anisotropy in mass composition above 10^18.7 eV at a confidence level of 3.3σ. The anisotropy is observed independently at each of the four fluorescence telescope sites. Interpretations of possible causes of the observed effect are discussed.
Ključne besede: Pierre Auger Observatory, indirect detection, fluorescence detection, ultra-high energy, cosmic rays, composition, anisotropy, Xmax, galactic plane
Objavljeno v RUNG: 03.10.2023; Ogledov: 953; Prenosov: 7
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