21. Analysis of TAx4 hybrid trigger and eventsS. Kim, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Telescope Array is the largest ultra-high energy cosmic ray hybrid detector in the Northern hemisphere. While the TAx4 Surface Detector (TAx4 SD) has a duty cycle of ~ 100%, it should be noted that the TAx4 Fluorescence Detector (TAx4 FD) observes the full longitudinal profile of the cosmic ray air showers and therefore is able to determine their energies more accurately than TAx4 SD. In addition, observing cosmic rays in hybrid mode (“hybrid events”) has several advantages. Events seen in hybrid mode by the TAx4 FD and SD are used to establish the energy scale of the TAx4 SD. Moreover, the FD longitudinal profile is used to determine the mass composition of the primary comic ray particles, when the event geometries are well constrained by FD and SD measurements simultaneously. Despite large differences in the TAx4 SD/FD stand-alone performances, both detector types complement each other in measuring important physical quantities. Since August 2019, direction, energy, and Xmax can be obtained from reconstructing hybrid events. In this poster, preliminary analysis of TAx4 hybrid trigger and TAx4 hybrid events will be presented with focus on energy and Xmax observations.
Ključne besede: Telescope Array, TAx4, indirect detection, hybrid detection, hybrid trigger, ground array, fluorescence detection, ultra-high energy, cosmic rays, energy, Xmax
Objavljeno v RUNG: 03.10.2023; Ogledov: 650; Prenosov: 6
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22. Telescope Array Combined Fit to Cosmic Ray Spectrum and CompositionD. Bergman, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: We present the result of fits of an astrophysical model of UHECR sources to the energy spectrum measured using the Telescope Array (TA) surface detectors and the composition data measured by TA fluorescence detectors in stereo mode. The astrophysical model consists of identical sources, uniformly distributed with a density which evolves with age, where groups of nuclei with varying fractions are accelerated producing a power law source with a rigidity-dependent cutoff. The model includes the propagation effects of photo-pion production, photo-nuclear disintegration and general energy loss from universal expansion. Comparison of model data with detector data in both the energy and the Xmax distributions is done via a forward-folding description of detector effects. A prediction of the cosmogenic neutrino flux at Earth resulting from the cosmic rays produced in the model with these fit values is also presented. The predicted flux is considerably higher than other similar fits to Auger data have previously predicted.
Ključne besede: Telescope Array, indirect detection, stereo detection, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, composition, combined fit, cosmogenic neutrinos, multimessenger
Objavljeno v RUNG: 02.10.2023; Ogledov: 743; Prenosov: 5
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23. Telescope Array 10-Year Monocular Spectrum MeasurementD. Bergman, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Telescope Array (TA) is the largest cosmic ray detector in the northern hemisphere. We present a measurement of the cosmic ray energy spectrum for energies above 10^17.5 eV using fluorescence telescopes in monocular mode. A novel weather classification scheme using machine learning was used to select data parts with good weather to ensure the quality of the fluorescence data. The data from the Black Rock Mesa (BR) and Long Ridge (LR) fluorescence telescope stations were analysed separately in monocular mode, with the calculated fluxes combined into a single spectrum. The 10-year monocular combined cosmic ray energy spectrum is in excellent agreement with previous measurements from the northern hemisphere. We present fits of the combined spectrum to a series of broken power law models. A thrice-broken power law is observed to be the best fit considering the Poisson deviance per degrees of freedom. The three breaks suggest an additional feature of the spectrum between the previously observed Ankle at 10^18.7 eV and the GZK suppression at 10^19.8 eV.
Ključne besede: Telescope Array, indirect detection, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, composition, machine learning, weather classification
Objavljeno v RUNG: 02.10.2023; Ogledov: 675; Prenosov: 5
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24. Recent measurement of the Telescope Array energy spectrum and observation of the shoulder feature in the Northern HemisphereD. Ivanov, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Telescope Array (TA) is a hybrid cosmic ray detector deployed in 2007 in Millard County, Utah, USA, which consists of a surface detector of 507 plastic scintillation counters spanning a 700 km^2 area on the ground that is overlooked by three fluorescence detector stations. The High Resolution Fly's Eye (HiRes) experiment is a predecessor of TA, which consisted of two fluorescence detector stations operating from 1997 until 2006 from Dugway Proving Ground, Utah, USA, and which was the the first cosmic ray experiment with sufficient resolution and exposure to successfully observe the Greisen–Zatsepin–Kuzmin (GZK) suppression at 10^19.75 eV. In this work, we present an updated TA energy spectrum result and a joint fit of independent spectrum measurements by the TA surface detector, TA fluorescence detector, and HiRes fluorescence detector to a broken power law function, which exhibits the ankle, GZK suppression, and the new shoulder feature initially seen by the Pierre Auger Observatory in the Southern Hemisphere. HiRes and TA observe the shoulder feature in the Northern Hemisphere at 10^19.25 eV, with a statistical significance of 5.3 standard deviations.
Ključne besede: Telescope Array, High Resolution Fly's Eye, HiRes, indirect detection, hybrid detection, ground array, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, GZK
Objavljeno v RUNG: 02.10.2023; Ogledov: 543; Prenosov: 6
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25. Monocular Energy Spectrum using the TAx4 Fluorescence DetectorM. Potts, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Following the evidence for a hotspot in the arrival directions of the highest energy cosmic rays, the Telescope Array (TA) Experiment undertook the TAx4 upgrade to expand the area of our Surface Detectors (SD) by a factor of 4 and have added new Fluorescence Detector (FD) stations to view over the new SD arrays. Currently, TAx4 consists of 12 FDs and 257 SDs, of a planned 500, at a spacing of 2.08 km spread over two sites. TAx4 North (4 FDs), completed in 2018, views over the northern wing of the new SD, and TAx4 South (8 FDs), completed in 2019, views over the southern wing. Both FD sites are in routine observation, with data being taken remotely at the TAx4 South site. In this work, we will report on the performance of the TAx4 FD, showing data/MC comparisons. We will present a preliminary monocular energy spectrum for the TAx4 fluorescence detector and the progress of the hybrid analysis.
Ključne besede: Telescope Array, TAx4, indirect detection, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum
Objavljeno v RUNG: 02.10.2023; Ogledov: 552; Prenosov: 4
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26. 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
Objavljeno v RUNG: 02.10.2023; Ogledov: 736; Prenosov: 5
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27. 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: 590; Prenosov: 6
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28. 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: 717; Prenosov: 5
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29. 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: 770; Prenosov: 5
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30. Follow-up Search for UHE Photons from Gravitational Wave Sources with the Pierre Auger ObservatoryP. Ruehl, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: Multimessenger astronomy has become increasingly important during the past decade. Some astronomical objects have already been successfully observed in the light of multiple messenger signals, allowing for a much deeper understanding of their physical properties. The Pierre Auger Observatory has taken part in multimessenger astronomy with an exhaustive exploration of the ultra-high-energy sky. In this contribution, for the first time, a search for UHE photons from the sources of gravitational waves is presented. Interactions with the cosmic background radiation fields are expected to attenuate any possible flux of ultra-high-energy photons from distant sources and a non-negligible background of air shower events with hadronic origin makes an unambiguous identification of primary photons a challenging task. In the analysis presented here, a selection strategy is applied to both GW sources and air shower events aiming to provide maximum sensitivity to a possible photon signal. At the same time, a window is kept open for hypothetical new-physics processes, which might allow for much larger interaction lengths of photons in the extragalactic medium. Preliminary results on the UHE photon fluence from a selection of GW sources, including the binary neutron star merger GW170817 are presented.
Ključne besede: Pierre Auger Observatory, indirect detection, fluorescence detection, ultra-high energy, photons, cosmic rays, anisotropy, gravitational waves, multimessenger
Objavljeno v RUNG: 29.09.2023; Ogledov: 646; Prenosov: 6
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