111. 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: 741; Prenosov: 4
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112. 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: 556; Prenosov: 4
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113. Effects of Galactic magnetic field on the UHECR anisotropy studiesR. Higuchi, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Telescope Array (TA) and Auger experiments reported anisotropies in the arrival direction of ultrahigh-energy cosmic rays (UHECRs). In particular, Auger Collaboration reported a correlation
between UHECR events and the flux model of assumed sources and suggested a contribution of
starburst galaxies (SBGs) to the anisotropy of UHECRs. However, in their study, the effect of
coherent deflections by the galactic magnetic field (GMF) is not taken into account. In this study, we investigated the effect of the GMF on the arrival directions of UHECRs using the cosmic ray propagation code CRPropa3. We used a backtracking technique which consists of propagating antiparticles to map the flux outside the galaxy to at the earth. We estimate the systematic effects caused by GMF in the reported likelihood analysis. We conduct likelihood analysis for mock UHECR datasets based on the flux pattern through the GMF model. We found systematic decrease of (f_ani, �) due to GMF. As prospects for the TAx4 experiment and joint analysis of Auger and TA collaborations, we develop the likelihood analysis method with the convolution of the rigidity spectrum.
Ključne besede: Telescope Array, TAx4, ultra-high energy, cosmic rays, anisotropy, galactic magnetic field, starburst galaxies
Objavljeno v RUNG: 29.09.2023; Ogledov: 636; Prenosov: 5
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114. Downward Terrestrial Gamma-ray Flashes at the Pierre Auger Observatory?R. Colalillo, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: At the Pierre Auger Observatory, designed primarily to study ultra-high-energy cosmic rays, phenomena related to atmospheric electricity are also observed. Particularly, events have been detected with the surface detector, characterized by long-lasting signals (tens of microseconds) and event footprints much larger (up to 200 km2) than those produced by the highest energy cosmic rays. Moreover, some of them appear to be accompanied by smaller events occurring in the same area within about 1 ms and probably produced by the same phenomenon. A previously reported correlation with the World Wide Lightning Location Network, as well as the observation of very low-altitude clouds, confirm that such events are related to thunderstorms. An ad-hoc reconstruction points to high-energy particles being produced very close to the ground, suggesting that they originate from electrons accelerated to relativistic energies in strong electric fields inside low clouds, as is the case for terrestrial gamma-ray flashes above thunderstorms.
A clear explanation of the observed phenomenon is hindered by two facts. One is that the rate of such events, detected serendipitously, is very small (less than 2 events/year) and decreases further after optimization of the surface detector trigger for low-energy shower-events. The second is that most events show a puzzling lack of signals in the central part of the footprint. We have studied in detail both effects and will present such studies here. We developed a strategy for a dedicated trigger to enhance the detection efficiency for these events associated with atmospheric-electricity events.
Ključne besede: Pierre Auger Observatory, surface detection, ultra-high energy, cosmic rays, photons, electrons, gamma-ray flashes, lightning
Objavljeno v RUNG: 29.09.2023; Ogledov: 637; Prenosov: 6
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115. 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: 600; Prenosov: 6
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116. Performance and simulation of the surface detector array of the TAx4 experimentK. Fujisue, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The TAx4 experiment is a project to observe highest energy cosmic rays by expanding the detectionarea of the Telescope Array (TA) experiment with newly constructed surface detectors (SDs) andfluorescence detectors (FDs). New SDs are arranged in a square grid with 2.08 km spacing atthe north east and south east of the TA SD array. We use CORSIKA simulations and implementthe calibration data of the new SDs to calculate the performance of the new SDs. We comparethe data with the simulation and validate the performance of the SDs. The comparison and theperformance will be shown in the presentation.
Ključne besede: Telescope Array, TAx4, indirect detection, ground array, surface detection, ultra-high energy, cosmic rays, CORSIKA
Objavljeno v RUNG: 29.09.2023; Ogledov: 563; Prenosov: 5
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117. Science with the Global Cosmic-ray Observatory (GCOS)Rafael Alves Batista, M. Ahlers, Pedro Assis, Markus Gottfried Battisti, J. A. Bellido, S. Bhatnagar, K. Bismark, Teresa Bister, Martina Boháčová, Serguei Vorobiov, 2023, objavljeni znanstveni prispevek na konferenci Opis: The Global Cosmic-ray Observatory (GCOS) is a proposed large-scale observatory for studying
ultra-high-energy cosmic particles, including ultra-high-energy cosmic rays (UHECRs), photons,
and neutrinos. Its primary goal is to characterise the properties of the highest-energy particles in
Nature with unprecedented accuracy, and to identify their elusive sources. With an aperture at least a ten-fold larger than existing observatories, this next-generation facility should start operating after 2030, when present-day detectors will gradually cease their activities. Here we briefly review the scientific case motivating GCOS. We present the status of the project, preliminary ideas for its design, and some estimates of its capabilities.
Ključne besede: ultra-high-energy cosmic rays, UHE photons, UHE neutrinos, the Global Cosmic-ray Observatory project
Objavljeno v RUNG: 27.09.2023; Ogledov: 929; Prenosov: 5
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118. Outreach activities at the Pierre Auger ObservatoryK.S. Caballero-Mora, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Pierre Auger Observatory, sited in Malargüe, Argentina, is the largest observatory available for measuring ultra-high-energy cosmic rays (UHECR). The Auger Collaboration has measured and analysed an unprecedented number of UHECRs. Along with making important scientific discoveries, for example, the demonstration that cosmic rays above 8 EeV are of extragalactic origin and the observation of a new feature in the energy spectrum at around 13 EeV, outreach work has been carried out across the 18 participating countries and online. This program ranges from talks to a varied audience, to the creation of a local Visitor Center, which attracts 8000 visitors annually, to initiating masterclasses. Permanent and temporary exhibitions have been prepared both in reality and virtually. Science fairs for elementary- and high-school students have been organised, together with activities associated with interesting phenomena such as eclipses. In addition, we participate in international events such as the International Cosmic Day, Frontiers from H2020, and the International Day of Women and Girls in Science. Part of the Collaboration website is aimed at the general public. Here the most recent articles published are summarised. Thus the Collaboration informs people about work in our field, which may seem remote from everyday life. Furthermore, the Auger Observatory has been a seed for scientific and technological activities in and around Malargüe. Different outreach ventures that already have been implemented and others which are foreseen will be described.
Ključne besede: Pierre Auger Observatory, indirect detection, ultra-high energy, cosmic rays, outreach, open data
Objavljeno v RUNG: 26.09.2023; Ogledov: 614; Prenosov: 5
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119. Highlights from the Telescope Array experimentGrigory I. Rubtsov, R. U. Abbasi, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci (vabljeno predavanje) Opis: The Telescope Array (TA) is the largest cosmic ray observatory in the Northern Hemisphere. It is designed to measure the properties of cosmic rays over a wide range of energies. TA with it's low energy extension (TALE) observe cosmic-ray induced extensive air showers between 2 PeV and 100 EeV in hybrid mode using multiple instruments, including an array of scintillator detectors at the Earth's surface and telescopes to measure the fluorescence and Cerenkov light. The statistics at the highest energies is being enhanced with the ongoing construction of the TAx4 experiment which will quadruple the surface area of the detector. We review the present status of the experiments and most recent physics results on the cosmic ray anisotropy, chemical composition and energy spectrum. Notable highlights include a new feature in the energy spectrum at about 10^19.2 eV, and a new clustering of events in the direction of Perseus-Pisces supercluster above this energy. We also report on updated diffuse photon flux limits and new spectrum and composition results in the lower energy range from the TALE extension.
Ključne besede: Telescope Array, TALE, low energy extension, TAx4, indirect detection, hybrid detection, ground array, fluorescence detection, Cherenkov light, ultra-high energy, cosmic rays, energy spectrum, composition, anisotropy
Objavljeno v RUNG: 26.09.2023; Ogledov: 677; Prenosov: 5
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120. Performance study update of observations in divergent mode for the Cherenkov Telescope ArrayA. Donini, Saptashwa Bhattacharyya, Judit Pérez Romero, Samo Stanič, Veronika Vodeb, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Miha Živec, 2023, objavljeni znanstveni prispevek na konferenci Opis: Due to the limited field of view (FoV) of Cherenkov telescopes, the time needed to achieve target sensitivity for surveys of the extragalactic and Galactic sky is large. To optimize the time spent to perform such surveys, a so-called “divergent mode” of the Cherenkov Telescope Array Observatory (CTAO) was proposed as an alternative observation strategy to the traditional parallel pointing. In the divergent mode, each telescope points to a position in the sky that is slightly offset, in the outward direction, from the original center of the field of view. This bring the advantage of increasing the total instantaneous arrays’ FoV. From an enlarged field of view also benefits the search for very-high-energy transient sources, making it possible to cover large sky regions in follow-up observations, or to quickly cover the probability sky map in case of Gamma Ray Bursts (GRB), Gravitational Waves (GW), and other transient events. In this contribution, we present the proposed implementation of the divergent pointing mode and its first preliminary performance estimation for the southern CTAO array.
Ključne besede: Cherenkov Telescope Array, CTAO, divergent mode, very-high-energy transient sources
Objavljeno v RUNG: 26.09.2023; Ogledov: 638; Prenosov: 5
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