31. 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: 667; Prenosov: 4
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32. 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: 815; Prenosov: 5
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33. Results from the Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experimentE.S. Seo, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment took high-energy cosmic ray data for 539 days after its successful installation on the ISS in August 2017. The ISS-CREAM instrument is configured with complementary particle detectors capable of measuring elemental spectra for Z = 1 - 26 nuclei in the energy range 10^12 – 10^15 eV; as well as electrons at multi-TeV energies. The goal is to understand cosmic ray origin, acceleration, and propagation by extending direct measurements of cosmic rays to energies that overlap the energy region of air showers measurements. The four layers of finely segmented Silicon Charge Detectors provide precise charge measurements. They have been designed to minimize hits of accompanying backscattered particles in the same segment as the incident cosmic ray particle to avoid charge misidentification. The sampling tungsten/scintillating-fiber calorimeter, which is identical to the calorimeter for prior CREAM balloon flights, provides energy measurements. In addition, scintillator-based Top and Bottom Counting Detectors distinguish electrons from nuclei. Our analysis indicates that the data extend well above 100 TeV. Recent results from the ongoing analysis are presented.
Ključne besede: ISS-CREAM, silicon charge detector, calorimeter, direct detection, cosmic rays, electrons, energy spectrum, composition
Objavljeno v RUNG: 26.09.2023; Ogledov: 856; Prenosov: 6
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34. Cosmic-ray Heavy Nuclei Spectra Using the ISS-CREAM InstrumentS.C. Kang, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) was designed to study high-energy cosmic rays up to PeV and recorded data from August 22nd, 2017 to February 12th, 2019 on the ISS. In this analysis, the Silicon Charge Detector (SCD), CALorimeter (CAL), and Top and Bottom Counting Detectors (TCD/BCD) are used. The SCD is composed of four layers and provides the measurement of cosmic-ray charges with a resolution of ∼0.2e. The CAL comprises 20 interleaved tungsten plates and scintillators, measures the incident cosmic-ray particles' energies, and provides a high energy trigger. The TCD/BCDs consist of photodiode arrays and plastic scintillators and provide a low-energy trigger. In this analysis, the SCD top layer is used for charge determination. Here, we present the heavy nuclei analysis using the ISS-CREAM instrument.
Ključne besede: ISS-CREAM, silicon charge detector, calorimeter, direct detection, heavy nuclei, cosmic rays, energy spectrum, composition
Objavljeno v RUNG: 26.09.2023; Ogledov: 777; Prenosov: 5
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35. Beam Test Results of the ISS-CREAM CalorimeterH.G. Zhang, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Cosmic Ray Energetics And Mass experiment for the International Space Station (ISS-CREAM) was installed on the ISS to measure high-energy cosmic-ray elemental spectra for the charge range Z=1 to 26. The ISS-CREAM instrument includes a tungsten scintillating-fiber calorimeter preceded by carbon targets for energy measurements. The carbon targets induces hadronic interactions, and showers of secondary particles develop in the calorimeter. The calorimeter was calibrated with electron beams at CERN. This beam test included position, energy, and angle scans of electron and pion beams together with a high-voltage scan for calibration and characterization. Additionally, an attenuation effect in the scintillating fibers was studied. In this paper, beam test results, including corrections for the attenuation effect, are presented.
Ključne besede: ISS-CREAM, calorimeter, particle accelerator, CERN, electron beam, direct detection, cosmic rays, energy spectrum, composition
Objavljeno v RUNG: 26.09.2023; Ogledov: 770; Prenosov: 4
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36. Constraining the sources of ultra-high-energy cosmic rays across and above the ankle with the spectrum and composition data measured at the Pierre Auger ObservatoryA. Abdul Halim, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, izvirni znanstveni članek Opis: In this work we present the interpretation of the energy spectrum and mass composition data as measured by the Pierre Auger Collaboration above 6 × 10[sup]17 eV. We use an astrophysical model with two extragalactic source populations to model the hardening of the cosmic-ray flux at around 5 × 10[sup]18 eV (the so-called "ankle" feature) as a transition between these two components. We find our data to be well reproduced if sources above the ankle emit a mixed composition with a hard spectrum and a low rigidity cutoff. The component below the ankle is required to have a very soft spectrum and a mix of protons and intermediate-mass nuclei. The origin of this intermediate-mass component is not well constrained and it could originate from either Galactic or extragalactic sources. To the aim of evaluating our capability to constrain astrophysical models, we discuss the impact on the fit results of the main experimental systematic uncertainties and of the assumptions about quantities affecting the air shower development as well as the propagation and redshift distribution of injected ultra-high-energy cosmic rays (UHECRs).
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, extensive air showers, UHECR propagation, UHECR energy spectrum, UHECR mass composition
Objavljeno v RUNG: 18.08.2023; Ogledov: 838; Prenosov: 8
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37. Recent results from the Pierre Auger ObservatorySerguei Vorobiov, 2022, objavljeni povzetek znanstvenega prispevka na konferenci (vabljeno predavanje) Opis: Ultra-high-energy cosmic rays (UHECRs) are mostly protons and heavier nuclei arriving on Earth from space and producing particle cascades in the atmosphere, ”extensive air showers”. As of today, the most precise and high-statistics data set of the rare (≤ 1 particle per sq.km per year above 10[sup]19 eV) UHECR events is obtained by the Pierre Auger Observatory, a large area (~3000 sq.km) hybrid detector in Argentina. The Auger Observatory determines the arrival directions and energies of the primary UHECR particles and provides constraints for their masses.
In this talk, I will present and discuss the recent results, including the detailed measurements of the cosmic-ray energy spectrum features, the study of the anisotropies in the UHECR arrival directions at large and intermediate angular scales, the multi-messenger searches, and the inferred cosmic-ray mass composition. Finally, the progress of the current upgrade of the Observatory, "AugerPrime" which is aimed at improving the sensitivity to the mass composition of ultra-high-energy cosmic rays, will be presented.
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, UHECR mass composition, energy spectrum, anisotropies, AugerPrime upgrade
Objavljeno v RUNG: 23.12.2022; Ogledov: 1504; Prenosov: 7
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39. e/p separation study using the ISS-CREAM top and bottom counting detectorsS. C. Kang, Y. Amarea, D. Angelaszek, N. Anthony, G. H. Choi, M. Chung, M. Copley, L. Derome, L. Eraud, C. Falana, Jon Paul Lundquist, 2019, objavljeni znanstveni prispevek na konferenci Opis: Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) is an experiment for studying the origin, acceleration, and propagation mechanisms of high-energy cosmic rays. The ISS-CREAM instrument was launched on the 14th of August 2017 to the ISS aboard the SpaceX-12 Dragon spacecraft. The Top and Bottom Counting Detectors (TCD/BCD) are parts of the ISS-CREAM instrument and designed for studying electron and gamma-ray physics. The TCD/BCD each consist of an array of 20 × 20 photodiodes on a plastic scintillator. The TCD/BCD can separate electrons from protons by using the difference between the shapes of electromagnetic and hadronic showers in the high energy region. The Boosted Decision Tree (BDT) method, which is a deep learning method, is used in this separation study. We will present results of the electron/proton separation study and rejection power in various energy ranges.
Ključne besede: instrumentations, high energy cosmic rays, particle detectors, composition
Objavljeno v RUNG: 08.02.2021; Ogledov: 2372; Prenosov: 0
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40. Mass Composition of Cosmic Rays with Energies above 10[sup]17.2 eV from the Hybrid Data of the Pierre Auger ObservatoryAlexey Yushkov, Andrej Filipčič, Gašper Kukec Mezek, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, objavljeni znanstveni prispevek na konferenci Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays (UHECR), UHECR hybrid detection, UHECR mass composition
Objavljeno v RUNG: 21.12.2020; Ogledov: 2419; Prenosov: 69
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