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24. Socrealizam kao prvi "pravac" jugoslovenske književnosti: Slovenija, Srbija, Hrvatska : predavanje na Institutu za slavistiko, Fakulteta za poljsko in klasično filologijo, Univerza Adama Mickiewicza v Poznanju, Poljska, 12. 3. 2025Darko Ilin, 2025, predavanje na tuji univerzi Ključne besede: socrealizem, jugoslovanska književnost, ideologija, Sonja Sever, Roksanda Njeguš
Objavljeno v RUNG: 28.04.2025; Ogledov: 4; Prenosov: 0
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25. An extremely energetic cosmic ray observed by a surface detector arrayR. U. Abbasi, M. Allen, R. Arimura, J. W. Belz, Douglas R. Bergman, S. A. Blake, K. Shin, I. J. Buckland, B. G. Cheon, Jon Paul Lundquist, 2023, izvirni znanstveni članek Opis: Cosmic rays are energetic charged particles from extraterrestrial sources, with the highest-energy events thought to come from extragalactic sources. Their arrival is infrequent, so detection requires instruments with large collecting areas. In this work, we report the detection of an extremely energetic particle recorded by the surface detector array of the Telescope Array experiment. We calculate the particle’s energy as 244 +- 29 (stat.) +51,-76 (syst.)
exa–electron volts (~40 joules). Its arrival direction points back to a void in the large-scale structure of the Universe. Possible explanations include a large deflection by the foreground magnetic field, an unidentified source in the local extragalactic neighborhood, or an incomplete knowledge of particle physics.
Ključne besede: ultra-high-energy cosmic rays, telescope array, extremely energetic cosmic-ray event
Objavljeno v RUNG: 23.04.2025; Ogledov: 154; Prenosov: 0
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26. Mass composition of ultrahigh energy cosmic rays from distribution of their arrival directions with the Telescope ArrayR. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Y. Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, Jon Paul Lundquist, 2024, izvirni znanstveni članek Opis: We use a new method to estimate the injected mass composition of ultrahigh cosmic rays (UHECRs) at energies higher than 10 EeV. The method is based on comparison of the energy-dependent distribution of cosmic ray arrival directions as measured by the Telescope Array (TA) experiment with that calculated in a given putative model of UHECR under the assumption that sources trace the large-scale structure (LSS) of the Universe. As we report in the companion Letter, the TA data show large deflections with respect to the LSS which can be explained, assuming small extragalactic magnetic fields (EGMF), by an intermediate composition changing to a heavy one (iron) in the highest energy bin. Here we show that these results are robust to uncertainties in UHECR injection spectra, the energy scale of the experiment and galactic magnetic fields. The assumption of weak EGMF, however, strongly affects this interpretation at all but the highest energies E > 100 EeV, where the remarkable isotropy of the data implies a heavy injected composition even in the case of strong EGMF. This result also holds if UHECR sources are as rare as 2 × 10[sup]−5 Mpc[sup]−3, that is the conservative lower limit for the source number density.
Ključne besede: ultrahigh energy cosmic rays, large-scale structure, extragalactic magnetic fields, UHECR propagation, Telescope Array, UHECR mass composition, UHECR arrival directions
Objavljeno v RUNG: 23.04.2025; Ogledov: 126; Prenosov: 0
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27. Isotropy of Cosmic Rays beyond 10[sup]20 eV Favors Their Heavy Mass CompositionR. U. Abbasi, Jon Paul Lundquist, 2024, izvirni znanstveni članek Opis: We report an estimation of the injected mass composition of ultrahigh energy cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is inferred from an energy-dependent sky distribution of UHECR events observed by the Telescope Array surface detector by comparing it to the Large Scale Structure of the local Universe. In the case of negligible extragalactic magnetic fields (EGMFs), the results are consistent with a relatively heavy injected composition at E ∼ 10 EeV that becomes lighter up to E ∼ 100 EeV, while the composition at E > 100 EeV is very heavy. The latter is true even in the presence of highest experimentally allowed extragalactic magnetic fields, while the composition at lower energies can be light if a strong EGMF is present. The effect of the uncertainty in the galactic magnetic field on these results is subdominant.
Ključne besede: ultrahigh energy cosmic rays (UHECRs), Large Scale Structure, extragalactic magnetic fields, UHECR propagation, Telescope Array surface detector, UHECR mass composition, UHECR arrival directions
Objavljeno v RUNG: 23.04.2025; Ogledov: 131; Prenosov: 0
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28. Intermediate fluence downward terrestrial gamma ray flashes as observed by the Telescope Array Surface DetectorR. U. Abbasi, N. Kieu, P. R. Krehbiel, J. W. Belz, M. M. F. Saba, W. Rison, M. A. Stanley, D. Rodeheffer, D. Mazzucco, Jon Paul Lundquist, 2024, izvirni znanstveni članek Opis: On 11 September 2021, two small thunderstorms developed over the Telescope Array Surface Detector (TASD) that produced an unprecedented number of six downward terrestrial gamma ray flashes (TGFs) within one‐hour timeframe. The TGFs occurred during the initial stage of negative cloud‐to‐ground flashes whose return strokes had increasingly large peak currents up to 223 kA, 147 GeV energy deposit in up to 25 1.2 km‐spaced surface detectors, and intermittent bursts of gamma‐rays with total durations up to 717 s. The analyses are based on observations recorded by the TASD network, complemented by data from a 3D lightning mapping array, broadband VHF interferometer, fast electric field change sensor, high‐speed video camera, and the National Lightning Detection Network. The TGFs of the final two flashes had gamma fluences of and 8, logarithmically bridging the gap between previous TASD and satellite‐based detections. The observations further emphasize the similarity between upward and downward TGF varieties, suggesting a common mechanism for their production.
Ključne besede: Telescope Array Surface Detector, terrestrial gamma ray flashes, 3D lightning mapping array, broadband VHF interferometer, fast electric field change sensor, high‐speed video camera, National Lightning Detection Network, TGF fluence measurement
Objavljeno v RUNG: 23.04.2025; Ogledov: 155; Prenosov: 0
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29. First time-resolved leader spectra associated with a downward terrestrial gamma-ray flash detected at the Telescope Array Surface DetectorN. Kieu, R. U. Abbasi, M. M. F. Saba, J. W. Belz, P. R. Krehbiel, M. A. Stanley, F. J. Gordillo-Vazquez, M. Passas-Varo, T. Warner, Jon Paul Lundquist, 2024, izvirni znanstveni članek Opis: Optical emissions associated with Terrestrial Gamma ray Flashes (TGFs) have recently become important subjects in space‐based and ground‐based observations as they can help us understand how TGFs are produced during thunderstorms. In this paper, we present the first time‐resolved leader spectra of the optical component associated with a downward TGF. The TGF was observed by the Telescope Array Surface Detector (TASD) simultaneously with other lightning detectors, including a Lightning Mapping Array (LMA), an INTerFerometer (INTF), a Fast Antenna (FA), and a spectroscopic system. The spectroscopic system recorded leader spectra at 29,900 frames per second (33.44 s time resolution), covering a spectral range from 400 to 900 nm, with 2.1 nm per pixel. The recordings of the leader spectra began 11.7 ms before the kA return stroke and at a height of 2.37 km above the ground. These spectra reveal that optical emissions of singly ionized nitrogen and oxygen occur between 167 s before and 267 s after the TGF detection, while optical emissions of neutrals (H I, 656 nm; N I, 744 nm, and O I, 777 nm) occur right at the moment of the detection. The time‐dependent spectra reveal differences in the optical emissions of lightning leaders with and without downward TGFs.
Ključne besede: Telescope Array Surface Detector, terrestrial gamma‐ray flashes, time‐resolved tgf leader spectra
Objavljeno v RUNG: 22.04.2025; Ogledov: 156; Prenosov: 0
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30. Multimessenger studies with the Pierre Auger ObservatoryJon Paul Lundquist, Andrej Filipčič, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2025, objavljeni znanstveni prispevek na konferenci Opis: The Pierre Auger Observatory, the world’s largest ultra-high-energy (UHE) cosmic ray (CR) detector, plays a crucial role in multi-messenger astroparticle physics with its high sensitivity to UHE photons and neutrinos. Recent Auger Observatory studies have set stringent limits on the diffuse and point-like fluxes of these particles, enhancing constraints on dark-matter models and UHECR sources. Although no temporal coincidences of neutrinos or photons with LIGO/Virgo gravitational wave events have been observed, competitive limits on the energy radiated in these particles have been established, particularly from the GW170817 binary neutron star merger. Additionally, correlations between the arrival directions of UHECRs and high-energy neutrinos have been explored using data from the IceCube Neutrino Observatory, ANTARES, and the Auger Observatory, providing additional neutrino flux constraints. Efforts to correlate UHE neutron fluxes with gamma-ray sources within our galaxy continue, although no significant excesses have been found. These collaborative and multi-faceted efforts underscore the pivotal role of the Auger Observatory in advancing multi-messenger astrophysics and probing the most extreme environments of the Universe.
Ključne besede: high-energy particle physics, astrophysics, ultra-high energy cosmic rays, neutrinos, gravitional waves
Objavljeno v RUNG: 22.04.2025; Ogledov: 171; Prenosov: 0
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