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41.
Air Shower Detection by Bistatic Radar
J. P. Lundquist, M. Abou Bakr Othman, 2011, published scientific conference contribution

Abstract: Progress in the field of high‐energy cosmic rays is currently limited by the rarity of the most interesting rays striking the Earth. Indeed, the continuation of the field beyond the current generation of observatories may become financially and practically impossible if new ways are not found to achieve remote coverage over large portions of the Earth’s surface. We describe the development of an observatory based on such a new technique: the remote sensing via bistatic radar technology of cosmic ray induced extensive air showers. We build on pilot studies performed by MARIACHI which have demonstrated that air shower radar echoes are detectable, the opportunity afforded by the location of the Northern Hemisphere’s largest “conventional” cosmic ray observatory (The Telescope Array) in radio‐quiet western Utah, and the donation of analog television transmission equipment to this effort by a local television station.
Found in: ključnih besedah
Summary of found: ... UHECR, Remote sensing, Television broadcasting, Cosmic rays, General...
Keywords: UHECR, Remote sensing, Television broadcasting, Cosmic rays, General procedures and instrumentation, Radar telescopes
Published: 29.04.2020; Views: 1591; Downloads: 0
.pdf Fulltext (4,99 MB)

42.
The Cosmic Ray Energy Spectrum between 2 PeV and 2 EeV Observed with the TALE Detector in Monocular Mode
J. P. Lundquist, R.U. Abbasi, 2018, original scientific article

Abstract: We report on a measurement of the cosmic ray energy spectrum by the Telescope Array Low-Energy Extension (TALE) air fluorescence detector (FD). The TALE air FD is also sensitive to the Cherenkov light produced by shower particles. Low-energy cosmic rays, in the PeV energy range, are detectable by TALE as Cherenkov events. Using these events, we measure the energy spectrum from a low energy of ~2 PeV to an energy greater than 100 PeV. Above 100 PeV, TALE can detect cosmic rays using air fluorescence. This allows for the extension of the measurement to energies greater than a few EeV. In this paper, we describe the detector, explain the technique, and present results from a measurement of the spectrum using ~1000 hr of observation. The observed spectrum shows a clear steepening near 10^17.1 eV, along with an ankle-like structure at 10^16.2 eV. These features present important constraints on the origin of galactic cosmic rays and on propagation models. The feature at 10^17.1 eV may also mark the end of the galactic cosmic ray flux and the start of the transition to extragalactic sources.
Found in: ključnih besedah
Summary of found: ...astroparticle physics, cosmic rays, UHECR, energy spectrum...
Keywords: astroparticle physics, cosmic rays, UHECR, energy spectrum
Published: 30.04.2020; Views: 1646; Downloads: 0
.pdf Fulltext (4,40 MB)

43.
Study of muons from ultrahigh energy cosmic ray air showers measured with the Telescope Array experiment
J. P. Lundquist, R.U. Abbasi, 2018, original scientific article

Abstract: One of the uncertainties in the interpretation of ultrahigh energy cosmic ray data comes from the hadronic interaction models used for air shower Monte Carlo (MC) simulations. The number of muons observed at the ground from ultrahigh energy cosmic ray–induced air showers is expected to depend upon the hadronic interaction model. One may therefore test the hadronic interaction models by comparing the measured number of muons with the MC prediction. In this paper, we present the results of studies of muon densities in ultrahigh energy extensive air showers obtained by analyzing the signal of surface detector stations which should have high muon purity. The muon purity of a station will depend on both the inclination of the shower and the relative position of the station. In seven years’ data from the Telescope Array experiment, we find that the number of particles observed for signals with an expected muon purity of ∼65% at a lateral distance of 2000 m from the shower core is 1.72± 0.10(stat)±0.37(syst) times larger than the MC prediction value using the QGSJET II-03 model for proton-induced showers. A similar effect is also seen in comparisons with other hadronic models such as QGSJET II-04, which shows a 1.67±0.10±0.36 excess. We also studied the dependence of these excesses on lateral distances and found a slower decrease of the lateral distribution of muons in the data as compared to the MC, causing larger discrepancy at larger lateral distances.
Found in: ključnih besedah
Summary of found: ... UHECR, cosmic rays, muons, particle physics...
Keywords: UHECR, cosmic rays, muons, particle physics
Published: 30.04.2020; Views: 1501; Downloads: 0
.pdf Fulltext (2,16 MB)

44.
Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope Array
J. P. Lundquist, M. G. Aartsen, 2016, original scientific article

Abstract: This paper presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECR magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.
Found in: ključnih besedah
Summary of found: ...their cross-correlation with the ultrahigh-energy cosmic ray ( UHECR) samples as a function of angular separation....
Keywords: UHECR, cosmic rays, neutrinos, multi-messenger physics, anisotropy
Published: 30.04.2020; Views: 1542; Downloads: 0
.pdf Fulltext (2,49 MB)

45.
The energy spectrum of ultra-high-energy cosmic rays measured by the Telescope Array FADC fluorescence detectors in monocular mode
J. P. Lundquist, T. Abu-Zayyad, 2013, original scientific article

Abstract: We present a measurement of the energy spectrum of ultra-high-energy cosmic rays performed by the Telescope Array experiment using monocular observations from its two new FADC-based fluorescence detectors. After a short description of the experiment, we describe the data analysis and event reconstruction procedures. Since the aperture of the experiment must be calculated by Monte Carlo simulation, we describe this calculation and the comparisons of simulated and real data used to verify the validity of the aperture calculation. Finally, we present the energy spectrum calculated from the merged monocular data sets of the two FADC-based detectors, and also the combination of this merged spectrum with an independent, previously published monocular spectrum measurement performed by Telescope Array’s third fluorescence detector [T. Abu-Zayyad et al., The energy spectrum of Telescope Array’s middle drum detector and the direct comparison to the high resolution fly’s eye experiment, Astroparticle Physics 39 (2012) 109-119, http://dx.doi.org/10.1016/j.astropartphys.2012.05.012, Available from: ]. This combined spectrum corroborates the recently published Telescope Array surface detector spectrum [T. Abu-Zayyad, et al., The cosmic-ray energy spectrum observed with the surface detector of the Telescope Array experiment, ApJ 768 (2013) L1, http://dx.doi.org/10.1088/2041-8205/768/1/L1, Available from: ] with independent systematic uncertainties.
Found in: ključnih besedah
Summary of found: ... UHECR, Energy spectrum, Fluorescence, Monocular...
Keywords: UHECR, Energy spectrum, Fluorescence, Monocular
Published: 19.05.2020; Views: 1504; Downloads: 0
.pdf Fulltext (926,83 KB)

46.
Evidence for a Supergalactic Structure of Magnetic Deflection Multiplets of Ultra-High Energy Cosmic Rays
J. P. Lundquist, R. Abbasi, 2020, original scientific article

Abstract: Evidence for a large-scale supergalactic cosmic ray multiplet (arrival directions correlated with energy) structure is reported for ultra-high energy cosmic ray (UHECR) energies above 10^19 eV using seven years of data from the Telescope Array (TA) surface detector and updated to 10 years. Previous energy-position correlation studies have made assumptions regarding magnetic field shapes and strength, and UHECR composition. Here the assumption tested is that, since the supergalactic plane is a fit to the average matter density of the local Large Scale Structure (LSS), UHECR sources and intervening extragalactic magnetic fields are correlated with this plane. This supergalactic deflection hypothesis is tested by the entire field-of-view (FOV) behavior of the strength of intermediate-scale energy-angle correlations. These multiplets are measured in spherical cap section bins (wedges) of the FOV to account for coherent and random magnetic fields. The structure found is consistent with supergalactic deflection, the previously published energy spectrum anisotropy results of TA (the hotspot and coldspot), and toy-model simulations of a supergalactic magnetic sheet. The seven year data post-trial significance of this supergalactic structure of multiplets appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be 4.19σ. The ten years of data post-trial significance is 4.09σ. Furthermore, the starburst galaxy M82 is shown to be a possible source of the TA Hotspot, and an estimate of the supergalactic magnetic field using UHECR measurements is presented.
Found in: ključnih besedah
Summary of found: ...is reported for ultra-high energy cosmic ray ( UHECR) energies above 10^19 eV using seven years...
Keywords: astroparticle physics, cosmic rays, UHECR, supergalactic plane, multiplets, magnetic deflection, large-scale structure of universe
Published: 19.05.2020; Views: 1567; Downloads: 0
.pdf Fulltext (4,40 MB)

47.
Anisotropies of the highest energy cosmic-ray events recorded by the Pierre Auger Observatory in 15 years of operation
Lukas Zehrer, Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Marta Trini, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, Lorenzo Caccianiga, 2019, published scientific conference contribution

Found in: ključnih besedah
Summary of found: ...ultra-high energy cosmic rays ( UHECR), UHECR anisotropies, Pierre Auger Observatory...
Keywords: ultra-high energy cosmic rays (UHECR), UHECR anisotropies, Pierre Auger Observatory
Published: 16.06.2020; Views: 1512; Downloads: 70
.pdf Fulltext (1,65 MB)

48.
Measurement of the cosmic ray flux near the second knee with the Pierre Auger Observatory
Lukas Zehrer, Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Marta Trini, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, Alan Coleman, 2019, published scientific conference contribution

Found in: ključnih besedah
Summary of found: ...ultra-high energy cosmic rays ( UHECR), UHECR energy spectrum, second knee, Pierre Auger...
Keywords: ultra-high energy cosmic rays (UHECR), UHECR energy spectrum, second knee, Pierre Auger Observatory
Published: 16.06.2020; Views: 1518; Downloads: 54
.pdf Fulltext (557,92 KB)

49.
Search for magnetically-induced signatures in the arrival directions of ultra-high-energy cosmic rays measured at the Pierre Auger Observatory
Lukas Zehrer, Marko Zavrtanik, Danilo Zavrtanik, Serguei Vorobiov, Marta Trini, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, A. Aab, 2020, original scientific article

Found in: ključnih besedah
Summary of found: ...ultra-high-energy cosmic rays ( UHECR), Pierre Auger Observatory, UHECR arrival directions, galactic...
Keywords: ultra-high-energy cosmic rays (UHECR), Pierre Auger Observatory, UHECR arrival directions, galactic magnetic field, UHECR event multiplets
Published: 19.06.2020; Views: 1480; Downloads: 0
.pdf Fulltext (1,93 MB)

50.
Reconstruction of Vertical Events Recorded by the Surface Detector of the Pierre Auger Observatory
Lukas Zehrer, Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Marta Trini, Samo Stanič, Gašper Kukec Mezek, Andrej Filipčič, Daniela Mockler, 2019, published scientific conference contribution

Found in: ključnih besedah
Summary of found: ...ultra-high energy cosmic rays ( UHECRs), Pierre Auger Observatory, Auger Surface Detector, vertical...
Keywords: ultra-high energy cosmic rays (UHECRs), Pierre Auger Observatory, Auger Surface Detector, vertical UHECR events, event reconstruction
Published: 24.07.2020; Views: 1502; Downloads: 54
.pdf Fulltext (321,91 KB)

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