211. Evidence of Intermediate-Scale Energy Spectrum Anisotropy of Cosmic Rays E>10^19.2 eV with the Telescope Array Surface DetectorJon Paul Lundquist, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Evidence of an intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays of energies above 10^19.2 eV in the northern hemisphere, using 7 years of Telescope Array (TA) surface detector (SD) data. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at 139 R.A., 45 Dec., and has a deficit of events with energies 10^19.210^19.75 eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo
(MC) simulation to be 9x10^-5 (3.74 σ_global).
Ključne besede: UHECR, cosmic rays, energy spectrum, anisotropy
Objavljeno v RUNG: 29.04.2020; Ogledov: 2646; Prenosov: 82
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212. Evidence of Intermediate-Scale Energy Spectrum Anisotropy in the Northern Hemisphere from Telescope ArrayJon Paul Lundquist, 2018, objavljeni znanstveni prispevek na konferenci Opis: Evidence of an energy dependent intermediate-scale anisotropy has been found in the arrival directions of ultra-high energy cosmic rays in the northern hemisphere, using 7 years of TA surface detector data. The previously reported ``hot spot" excess E ≥ 10^19.75 EeV is found to correspond to a deficit, or ``cold spot," of events for 10^19.2≤ E < 10^19.75 EeV. This feature suggests energy dependent magnetic deflection of cosmic-rays. The global post-trial significance of the energy spectrum deviation is found to be 3.74σ.
Ključne besede: UHECR, cosmic rays, energy spectrum, anisotropy, magnetic deflection
Objavljeno v RUNG: 28.04.2020; Ogledov: 2765; Prenosov: 79
 Celotno besedilo (4,87 MB) |
213. Telescope Array Hot/Coldspot Study – Intermediate Scale AnisotropyJon Paul Lundquist, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Indications of energy dependent intermediate scale anisotropy has been found in the arrival directions of ultra high energy cosmic rays with energies above 20 EeV in the northern hemisphere, using 7 years of TA surface detector data. The previously reported “hotspot‘” excess for E>57 EeV is found to correspond to a deficit, or “coldspot ”, of events for energies 2057 EeV has a Li Ma statistical significance of 4.62σ, and the deficit for energies 20Ključne besede: cosmic rays, energy spectrum, anisotropy, magnetic deflection
Objavljeno v RUNG: 28.04.2020; Ogledov: 2765; Prenosov: 0
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214. Updated Results on the UHECR Hotspot Observed by the Telescope Array ExperimentK. Kawata, Jon Paul Lundquist, 2019, objavljeni znanstveni prispevek na konferenci Opis: The Telescope Array Experiment has observed an indication of intermediate-scale anisotropy in the UHECR arrival directions, called the Hotspot, with E>57 EeV around the Ursa Major using the first 5-year data during a period between May 2008 and May 2013 collected by the TA surface detector array. The chance probability of this hotspot in an isotropic cosmic-ray sky was calculated to be 3.4σ (post trial). In this paper, we will report on an update of this result using the 11-year data collected by the TA surface detectors with more than doubled exposure since the first publication.
Ključne besede: UHECR, cosmic rays, anisotropy
Objavljeno v RUNG: 28.04.2020; Ogledov: 2503; Prenosov: 80
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215. Track Reconstruction for ISS-CREAM Resulting in Improved Energy and Charge ResolutionsJon Paul Lundquist, 2019, objavljeni znanstveni prispevek na konferenci Opis: Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) has taken 1.5 years of direct measurements of high-energy cosmic ray (HECR) particles for energies from 10^12 to 10^15 eV. HECR particle identification is significantly improved by tracking particle-detector interactions from the calorimeter (CAL) back to the Silicon Charge Detector (SCD) for charge determination. A track finding algorithm resistant to such issues as particle multiplicity, backscatter, and electronic noise will be outlined. Also, shown is the energy resolution improvement, and the resulting all particle spectrum, provided by ensuring good particle tracks. This allows ISSCREAM to investigate how the energy distributions evolve, for protons all the way to iron nuclei, and will provide important information for models of galactic sources and HECR propagation.
Ključne besede: cosmic rays, high energy, detectors, track fitting
Objavljeno v RUNG: 28.04.2020; Ogledov: 2702; Prenosov: 84
Celotno besedilo (481,98 KB) |
216. Covering the celestial sphere at ultra-high energies: Full-sky cosmic-ray maps beyond the ankle and the flux suppressionJ. Biteau, Jon Paul Lundquist, 2019, objavljeni znanstveni prispevek na konferenci Opis: Despite deflections by Galactic and extragalactic magnetic fields, the distribution of ultra-high energy cosmic rays (UHECRs) over the celestial sphere remains a most promising observable for the identification of their sources. Thanks to a large number of detected events over the past years, a large-scale anisotropy at energies above 8 EeV has been identified, and there are also indications from the Telescope Array and Pierre Auger Collaborations of deviations from isotropy at intermediate angular scales (about 20 degrees) at the highest energies. In this contribution, we map the flux of UHECRs over the full sky at energies beyond each of two major features in the UHECR spectrum – the ankle and the flux suppression, and we derive limits for anisotropy on different angular scales in the two energy regimes. In particular, full-sky coverage enables constraints on low-order multipole moments without assumptions about the strength of higher-order multipoles. Following previous efforts from the two Collaborations, we build full-sky maps accounting for the relative exposure of the arrays and differences in the energy normalizations. The procedure relies on cross-calibrating the UHECR fluxes reconstructed in the declination band around the celestial equator covered by both observatories. We present full-sky maps at energies above ~10 EeV and ~50 EeV, using the largest datasets shared across UHECR collaborations to date. We report on anisotropy searches exploiting full-sky coverage and discuss possible constraints on the distribution of UHECR sources.
Ključne besede: UHECR, cosmic rays, anisotropy, Telescope Array, Pierre Auger Observatory
Objavljeno v RUNG: 28.04.2020; Ogledov: 2617; Prenosov: 82
Celotno besedilo (4,92 MB) |
217. Supergalactic Structure of Multiplets with the Telescope Array Surface DetectorJon Paul Lundquist, P. Sokolsky, 2019, objavljeni znanstveni prispevek na konferenci Opis: Evidence of supergalactic structure of multiplets has been found for ultra-high energy cosmic rays (UHECR) with energies above 10^19 eV using 7 years of data from the Telescope Array (TA) surface detector. The tested hypothesis is that UHECR sources, and intervening magnetic fields, may be correlated with the supergalactic plane, as it is a fit to the average matter density within the GZK horizon. This structure is measured by the average behavior of the strength of intermediate-scale correlations between event energy and position (multiplets). These multiplets are measured in wedge-like shapes on the spherical surface of the fieldof-view to account for uniform and random magnetic fields. The evident structure found is consistent with toy-model simulations of a supergalactic magnetic sheet and the previously published Hot/Coldspot results of TA. The post-trial probability of this feature appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be ~4.5σ.
Ključne besede: UHECR, cosmic rays, energy spectrum, anisotropy, large-scale structure, magnetic deflection
Objavljeno v RUNG: 28.04.2020; Ogledov: 2834; Prenosov: 150
Celotno besedilo (1,38 MB) |
218. Improving Particle Identification with Resistant Track Finding for the ISS-CREAM CalorimeterJon Paul Lundquist, objavljeni povzetek znanstvenega prispevka na konferenci Opis: Moving from Antarctic balloons to the International Space Station the Cosmic Ray Energetics And Mass detector (ISS-CREAM) has begun taking the highest energy direct measurements of cosmic ray (CR) particles ever attempted. ISS-CREAM will investigate how the energy distributions evolve, for protons all the way to iron nuclei, and will provide important information for models of galactic sources and CR propagation. The CR particle identification can be significantly improved by tracking particle-detector interactions from the calorimeter (for energy measurement) back to the Silicon Charge Detector for atomic number determination. A track finding algorithm resistant to such issues as particle multiplicity, backscatter, and noise is outlined.
Ključne besede: cosmic rays, high energy, track finding
Objavljeno v RUNG: 28.04.2020; Ogledov: 2931; Prenosov: 0
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219. Supergalactic Structure of Energy-Angle CorrelationsJon Paul Lundquist, P. Sokolsky, 2020, objavljeni znanstveni prispevek na konferenci Opis: Evidence for the supergalactic structure of multiplets (energy-angle correlations) has previously been shown using ultra-high energy cosmic ray (UHECR) data from Telescope Array (TA) with energies above 10^19 eV. The supergalactic deflection hypothesis (that UHECR sources and intervening magnetic fields are correlated) is measured by the all-sky behavior of the strength of
intermediate-scale correlations. The multiplets are measured in spherical surface wedge bins of the field-of-view to account for uniform and random magnetic fields. The structure found is consistent with the previously published energy spectrum anisotropy results of TA and toy-model simulations of a supergalactic magnetic sheet. The 7 year data post-trial significance of this feature appearing by chance, on an isotropic sky, was found by Monte Carlo simulation to be ∼4σ. The analysis has now been applied to 10 years of data.
Ključne besede: Cosmic rays, UHECR, energy spectrum, magnetic deflection, large-scale structure, supergalactic, multiplets
Objavljeno v RUNG: 27.04.2020; Ogledov: 2717; Prenosov: 85
Celotno besedilo (1,66 MB) |
220. Indications of Proton-Dominated Cosmic-Ray Composition above 1.6 EeVR.U. Abbasi, Jon Paul Lundquist, 2010, izvirni znanstveni članek Opis: We report studies of ultrahigh-energy cosmic-ray composition via analysis of depth of air shower maximum (Xmax), for air shower events collected by the High-Resolution Fly’s Eye (HiRes) observatory. The HiRes data are consistent with a constant elongation rate d⟨Xmax⟩/d[log(E)] of 47.9 ± 6.0 (stat) ± 3.2 (syst) g/cm^2/decade for energies between 1.6 and 63 EeV, and are consistent with a predominantly protonic composition of cosmic rays when interpreted via the QGSJET01 and QGSJET-II high-energy hadronic interaction models. These measurements constrain models in which the galactic-to-extragalactic transition is the cause of the energy spectrum ankle at 4×10^18 eV.
Ključne besede: Cosmic rays, Energy spectrum, Telescope Array, Hybrid, Ultra high energy
Objavljeno v RUNG: 27.04.2020; Ogledov: 2748; Prenosov: 0
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