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 71 - 80 / 15145678910111213 71.The hybrid energy spectrum of Telescope Array’s Middle Drum Detector and surface arrayJ. P. Lundquist, R.U. Abbasi, 2015, original scientific articleAbstract: The Telescope Array experiment studies ultra high energy cosmic rays using a hybrid detector. Fluorescence telescopes measure the longitudinal development of the extensive air shower generated when a primary cosmic ray particle interacts with the atmosphere. Meanwhile, scintillator detectors measure the lateral distribution of secondary shower particles that hit the ground. The Middle Drum (MD) fluorescence telescope station consists of 14 telescopes from the High Resolution Fly’s Eye (HiRes) experiment, providing a direct link back to the HiRes measurements. Using the scintillator detector data in conjunction with the telescope data improves the geometrical reconstruction of the showers significantly, and hence, provides a more accurate reconstruction of the energy of the primary particle. The Middle Drum hybrid spectrum is presented and compared to that measured by the Middle Drum station in monocular mode. Further, the hybrid data establishes a link between the Middle Drum data and the surface array. A comparison between the Middle Drum hybrid energy spectrum and scintillator Surface Detector (SD) spectrum is also shown.Found in: ključnih besedahSummary of found: ...Telescope Array experiment studies ultra high energy cosmic rays using a hybrid detector. Fluorescence telescopes...Keywords: Cosmic rays, Energy spectrum, Telescope Array, Hybrid, Ultra high energyPublished: 27.04.2020; Views: 1619; Downloads: 0 Fulltext (3,12 MB) 72.Indications of Proton-Dominated Cosmic-Ray Composition above 1.6 EeVJ. P. Lundquist, R.U. Abbasi, 2010, original scientific articleAbstract: 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.Found in: ključnih besedahSummary of found: ...with a predominantly protonic composition of cosmic rays when interpreted via the QGSJET01 and QGSJET-II...Keywords: Cosmic rays, Energy spectrum, Telescope Array, Hybrid, Ultra high energyPublished: 27.04.2020; Views: 1648; Downloads: 0 Fulltext (314,89 KB) 73.Supergalactic Structure of Energy-Angle CorrelationsP. Sokolsky, J. P. Lundquist, 2020, published scientific conference contributionAbstract: 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.Found in: ključnih besedahSummary of found: ...has previously been shown using ultra-high energy cosmic ray (UHECR) data from Telescope Array (TA)... ...Cosmic rays, UHECR, energy spectrum, magnetic deflection, large-scale structure,...Keywords: Cosmic rays, UHECR, energy spectrum, magnetic deflection, large-scale structure, supergalactic, multipletsPublished: 27.04.2020; Views: 1596; Downloads: 60 Fulltext (1,66 MB) 74.Improving Particle Identification with Resistant Track Finding for the ISS-CREAM CalorimeterJ. P. Lundquist, published scientific conference contribution abstractAbstract: 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.Found in: ključnih besedahSummary of found: ...balloons to the International Space Station the Cosmic Ray Energetics And Mass detector (ISS-CREAM) has... ...cosmic rays, high energy, track finding...Keywords: cosmic rays, high energy, track findingPublished: 28.04.2020; Views: 1671; Downloads: 0 Fulltext (3,23 MB) 75.Supergalactic Structure of Multiplets with the Telescope Array Surface DetectorP. Sokolsky, J. P. Lundquist, 2019, published scientific conference contributionAbstract: 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.Found in: ključnih besedahSummary of found: ...multiplets has been found for ultra-high energy cosmic rays (UHECR) with energies above 10^19 eV...Keywords: UHECR, cosmic rays, energy spectrum, anisotropy, large-scale structure, magnetic deflectionPublished: 28.04.2020; Views: 1738; Downloads: 108 Fulltext (1,38 MB) 76.Evidence of Intermediate-Scale Energy Spectrum Anisotropy in the Northern Hemisphere from Telescope ArrayJ. P. Lundquist, 2018, published scientific conference contributionAbstract: 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.Found in: ključnih besedahSummary of found: ...in the arrival directions of ultra-high energy cosmic rays in the northern hemisphere, using 7...Keywords: UHECR, cosmic rays, energy spectrum, anisotropy, magnetic deflectionPublished: 28.04.2020; Views: 1639; Downloads: 56 Fulltext (4,87 MB) 77.Telescope Array Hot/Coldspot Study – Intermediate Scale AnisotropyJ. P. Lundquist, published scientific conference contribution abstractAbstract: 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 20Found in: ključnih besedahSummary of found: ...the arrival directions of ultra high energy cosmic rays with energies above 20 EeV in...Keywords: cosmic rays, energy spectrum, anisotropy, magnetic deflectionPublished: 28.04.2020; Views: 1583; Downloads: 0 Fulltext (2,25 MB) 78.Updated Results on the UHECR Hotspot Observed by the Telescope Array ExperimentJ. P. Lundquist, K. Kawata, 2019, published scientific conference contributionAbstract: 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.Found in: ključnih besedahSummary of found: ...probability of this hotspot in an isotropic cosmic-ray sky was calculated to be 3.4σ (post... ...UHECR, cosmic rays, anisotropy...Keywords: UHECR, cosmic rays, anisotropyPublished: 28.04.2020; Views: 1428; Downloads: 55 Fulltext (934,91 KB) 79.Track Reconstruction for ISS-CREAM Resulting in Improved Energy and Charge ResolutionsJ. P. Lundquist, 2019, published scientific conference contributionAbstract: 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.Found in: ključnih besedahSummary of found: ... Cosmic Ray Energetics And Mass for the International... ...cosmic rays, high energy, detectors, track fitting...Keywords: cosmic rays, high energy, detectors, track fittingPublished: 28.04.2020; Views: 1679; Downloads: 59 Fulltext (481,98 KB) 80.Covering the celestial sphere at ultra-high energies: Full-sky cosmic-ray maps beyond the ankle and the flux suppressionJ. P. Lundquist, J. Biteau, 2019, published scientific conference contributionAbstract: 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.Found in: ključnih besedahSummary of found: ...fields, the distribution of ultra-high energy cosmic rays (UHECRs) over the celestial sphere remains a...Keywords: UHECR, cosmic rays, anisotropy, Telescope Array, Pierre Auger ObservatoryPublished: 28.04.2020; Views: 1551; Downloads: 57 Fulltext (4,92 MB)
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