101. Anisotropy search in the Ultra High Energy Cosmic Ray Spectrum in the Northern Hemisphere using latest data obtained with Telescope Array surface detectorT. Nonaka, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Telescope Array (TA) experiment is located in the western desert of Utah, USA and observes ultra-high energy cosmic rays in the northern hemisphere. At the energies, the shape of the cosmic ray energy spectrum carries information of the source distribution. We present the search for differences in spectrum shape in different parts of the sky using latest data of TA surface detector (SD) data. From this study, we observe an apparent enhancement in the region of the northern sky that contain nearby objects, such as the super-galactic plane. Details of this analysis will be presented.
Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, energy spectrum, anisotropy
Objavljeno v RUNG: 02.10.2023; Ogledov: 556; Prenosov: 5
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102. Insight Into Lightning Initiation via Downward Terrestrial Gamma-ray Flash Observations at Telescope ArrayJ. Remington, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Due to the difficulty of direct measurement of the thunderstorm environment, in particular the electric field strengths, the initial stages of lightning breakdown remain mysterious. The 1994 discovery of Terrestrial Gamma-ray Flashes (TGFs) and their implications for megaVolt potentials within thunderclouds has proved to be a valuable source of information about the breakdown process.
The Telescope Array Surface Detector (TASD) --- a 700 km^2 scintillator array in Western Utah, U.S.A --- coupled with a lightning mapping array, fast sferic (field change) sensor and broadband interferometer, has provided unique insight into the properties of this energetic radiation and of lightning initiation in general. In particular, microsecond-scale timing comparisons have clearly established that downward TGFs occur during strong initial breakdown pulses (IBPs) of downward negative cloud-to-ground and intracloud flashes. In turn, the IBPs are produced by streamer-based fast negative breakdown.
Investigations into downward TGFs with the TASD have significantly evolved with recent upgrades to lightning instrumentation. A second state-of-the-art broadband interferometer allows high-resolution stereo observation of lightning development. A high-speed optical video camera, set to be deployed in Spring 2021, will allow simultaneous observation of the visual component of lightning responsible for TGF production. Finally, a suite of ground based static electric field mills will provide new information on the large-scale properties of the thunderstorms in which downward TGFs arise.
In this talk, we present the most recent TGF observations from the Telescope Array.
Ključne besede: Telescope Array, ground array, ultra-high energy, cosmic rays, photons, terrestrial gamma-ray flashes, gamma-rays, lightning
Objavljeno v RUNG: 02.10.2023; Ogledov: 577; Prenosov: 6
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103. Cosmic Ray Composition between 2 PeV and 2 EeV measured by the TALE Fluorescence DetectorT. AbuZayyad, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Telescope Array (TA) cosmic rays detector located in the State
of Utah in the United States is the largest ultra high energy cosmic rays
detector in the northern hemisphere. The Telescope Array Low Energy Extension
(TALE) fluorescence detector (FD) was added to TA in order to lower the
detector's energy threshold, and has succeeded in measuring the cosmic rays
energy spectrum down to PeV energies, by making use of the direct Cherenkov
light produced by air showers. In this contribution we present the results
of a measurement of the cosmic-ray composition using TALE FD data collected
over a period of ∼7 years. TALE FD data is used to measure the Xmax distributions of showers seen in the energy range of 10^15.3 - 10^18.3 eV. The data distributions are fit to Monte Carlo distributions of {H, He, N, Fe} cosmic-ray primaries for energies up to 10^18 eV. Mean Xmax values are measured for the full energy range. TALE observes a light composition at the "Knee", that gets gradually heavier as energy increases toward the "Second-Knee". An increase in the Xmax elongation rate is observed at energies just above 10^17.3 eV indicating a change in the cosmic rays composition from a heavier to a lighter mix of primaries.
Ključne besede: Telescope Array, TALE, low energy extension, indirect detection, fluorescence detection, cerenkov light, ultra-high energy, cosmic rays, composition
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104. Cosmic Ray Energy Spectrum measured by the TALE Fluorescence DetectorT. AbuZayyad, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Telescope Array (TA) cosmic rays detector located in the State
of Utah in the United States is the largest ultra high energy cosmic rays
detector in the northern hemisphere. The Telescope Array Low Energy Extension
(TALE) fluorescence detector (FD) was added to TA in order to lower the
detector's energy threshold, and has succeeded in measuring the cosmic rays
energy spectrum down to PeV energies, by making use of the direct Cherenkov
light produced by air showers. In this contribution we present the results
of a measurement of the cosmic-ray energy spectrum using TALE FD data
collected over a period of ∼7 years. The data set used for this
measurement is the same one used for the mass composition measurement that is
presented, as a separate contribution, at this conference. The energy
spectrum shows features consistent with the "knee" and the "second knee"; a
similar result to our previous energy spectrum publication. This time
using a different hadronic model, and different event selection criteria as
explained in the text of this proceeding.
Ključne besede: Telescope Array, TALE, low energy extension, indirect detection, fluorescence detection, cerenkov light, ultra-high energy, cosmic rays, energy spectrum
Objavljeno v RUNG: 02.10.2023; Ogledov: 518; Prenosov: 6
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105. Cosmic Ray Composition in the Second Knee Region as Measured by the TALE Hybrid DetectorR. Abbasi, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Telescope Array Low-energy Extension (TALE) experiment is a hybrid air shower detector for the observation of air showers induced by cosmic rays with energy above 10^16 eV. The TALE detector consists of a Fluorescence Detector (FD) station with 10 FD telescopes located at the TA Middle Drum FD Station (itself made up of 14 FD telescopes), and a Surface Detector (SD) array made up of 80 scintillation counters, including 40 with 400 m spacing and 40 with 600 m spacing. A triggering system for the TALE-SD using an external trigger from the TALE-FD, a so-called hybrid trigger, allows for a lower energy threshold. The TALE hybrid trigger system has been working since 2018. Here we present an estimate of the performance of hybrid detection using a Monte Carlo simulation, and a first measurement of the cosmic ray composition and spectrum using the TALE-Hybrid detector.
Ključne besede: Telescope Array, TALE, low energy extension, indirect detection, hybrid detection, ground array, fluorescence detection, cerenkov light, ultra-high energy, cosmic rays, energy spectrum, composition
Objavljeno v RUNG: 02.10.2023; Ogledov: 641; Prenosov: 5
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106. A search for ultra-high-energy photons at the Pierre Auger Observatory exploiting air-shower universalityP. Savina, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Pierre Auger Observatory is the most sensitive detector to primary photons with energies
above ∼ 0.2 EeV. It measures extensive air showers using a hybrid technique that combines a
fluorescence detector (FD) with a ground array of particle detectors (SD). The signatures of a photon-induced air shower are a larger atmospheric depth at the shower maximum (Xmax) and a
steeper lateral distribution function, along with a lower number of muons with respect to the bulk of hadron-induced background. Using observables measured by the FD and SD, three photon
searches in different energy bands are performed. In particular, between threshold energies of 1–10 EeV, a new analysis technique has been developed by combining the FD-based measurement of Xmax with the SD signal through a parameter related to its muon content, derived from the universality of the air showers. This technique has led to a better photon/hadron separation and, consequently, to a higher search sensitivity, resulting in a tighter upper limit than before. The outcome of this new analysis is presented here, along with previous results in the energy ranges below 1 EeV and above 10 EeV. From the data collected by the Pierre Auger Observatory in about 15 years of operation, the most stringent constraints on the fraction of photons in the cosmic flux are set over almost three decades in energy.
Ključne besede: Pierre Auger Observatory, indirect detection, fluorescence detection, surface array, hybrid detection, ultra-high energy, cosmic rays, photons
Objavljeno v RUNG: 29.09.2023; Ogledov: 696; Prenosov: 5
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107. The UHECR dipole and quadrupole in the latest data from the original Auger and TA surface detectorsP. Tinyakov, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: The sources of ultra-high-energy cosmic rays are still unknown, but assuming standard physics, they are expected to lie within a few hundred megaparsecs from us. Indeed, over cosmological distances cosmic rays lose energy to interactions with background photons, at a rate depending on their mass number and energy and properties of photonuclear interactions and photon backgrounds. The universe is not homogeneous at such scales, hence the distribution of the arrival directions of cosmic rays is expected to reflect the inhomogeneities in the distribution of galaxies; the shorter the energy loss lengths, the stronger the expected anisotropies. Galactic and intergalactic magnetic fields can blur and distort the picture, but the magnitudes of the largest-scale anisotropies, namely the dipole and quadrupole moments, are the most robust to their effects. Measuring them with no bias regardless of any higher-order multipoles is not possible except with full-sky coverage. In this work, we achieve this in three energy ranges (approximately 8-16 EeV, 16-32 EeV, and 32-∞ EeV) by combining surface-detector data collected at the Pierre Auger Observatory until 2020 and at the Telescope Array (TA) until 2019, before the completion of the upgrades of the arrays with new scintillator detectors. We find that the full-sky coverage achieved by combining Auger and TA data reduces the uncertainties on the north-south components of the dipole and quadrupole in half compared to Auger-only results.
Ključne besede: Pierre Auger Observatory, Telescope Array, indirect detection, surface detection, ultra-high energy, cosmic rays, anisotropy, large scale, fully sky coverage, dipole, quadropole
Objavljeno v RUNG: 29.09.2023; Ogledov: 650; Prenosov: 4
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108. Event-by-event reconstruction of the shower maximum Xmax with the Surface Detector of the Pierre Auger Observatory using deep learningJ. Glombitza, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: The measurement of the mass composition of ultra-high energy cosmic rays constitutes a prime challenge in astroparticle physics. Most detailed information on the composition can be obtained from measurements of the depth of maximum of air showers, Xmax, with the use of fluorescence telescopes, which can be operated only during clear and moonless nights.
Using deep neural networks, it is now possible for the first time to perform an event-by-event reconstruction of Xmax with the Surface Detector (SD) of the Pierre Auger Observatory. Therefore, previously recorded data can be analyzed for information on Xmax, and thus, the cosmic-ray composition. Since the SD operates with a duty cycle of almost 100% and its event selection is less strict than for the Fluorescence Detector (FD), the gain in statistics with respect to the FD is almost a factor of 15 for energies above 10^19.5 eV.
In this contribution, we introduce the neural network particularly designed for the SD of the Pierre Auger Observatory. We evaluate its performance using three different hadronic interaction models, verify its functionality using Auger hybrid measurements, and find that the method can extract mass information on an event level.
Ključne besede: Pierre Auger Observatory, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, composition, neural network, machine learning
Objavljeno v RUNG: 29.09.2023; Ogledov: 649; Prenosov: 5
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109. Mass composition of Telescope Array's surface detectors events using deep learningI. Kharuk, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: We report on an improvement of deep learning techniques used for identifying primary particles of atmospheric air showers. The progress was achieved by using two neural networks. The first works as a classifier for individual events, while the second predicts fractions of elements in an ensemble of events based on the inference of the first network. For a fixed hadronic model, this approach yields an accuracy of 90% in identifying fractions of elements in an ensemble of events.
Ključne besede: Telescope Array, indirect detection, ground array, surface detection, ultra-high energy, cosmic rays, composition, deep learning, machine learning, neural networks
Objavljeno v RUNG: 29.09.2023; Ogledov: 721; Prenosov: 4
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110. Telescope Array anisotropy summaryI. Tkachev, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: In this talk, we summarise the results of recent anisotropy studies conducted by the Telescope Array (TA) collaboration. At largest scales we test the TA data for the presence of a dipole. On smaller scales, an update on the excess of events in the direction of Ursa Major previously found in the TA data will be presented. These flux variations may trace the distribution of UHECR sources. We will examine the data for correlations with large-scale structures in the nearby Universe, and as a result, hints for the chemical composition of primaries will be provided. We also discuss a related anisotropy of the UHECR spectrum.
Ključne besede: Telescope Array, indirect detection, ground array, surface detection, ultra-high energy, cosmic rays, composition, energy spectrum, anisotropy
Objavljeno v RUNG: 29.09.2023; Ogledov: 532; Prenosov: 4
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