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31.
Telescope Array anisotropy summary
J. P. Lundquist, M. Fukushima, 2018, published scientific conference contribution

Abstract: The Telescope Array has accumulated the largest UHECR data set in the Northern hemisphere. We make use of these data to search for large- and small-scale anisotropy of UHECR arrival directions. At small angular scales, we report an update on searches for clustering of events and on correlations with various classes of putative sources. At large angular scales, we revisit, with the new data and with new tests, the localized excess of events known as the TA “hot spot”. We review some other studies of the arrival directions and corresponding implications for the nature of UHECR sources.
Found in: ključnih besedah
Summary of found: ...The Telescope Array has accumulated the largest UHECR data set in the Northern hemisphere. We...
Keywords: UHECR, cosmic rays, anisotropy
Published: 29.04.2020; Views: 1447; Downloads: 60
.pdf Fulltext (581,87 KB)

32.
A systematic uncertainty on the energy scale of the Telescope Array fluorescence detectors
J. P. Lundquist, T. Fujii, 2018, published scientific conference contribution

Abstract: The Telescope Array experiment (TA) is the largest cosmic-ray detector in the northern hemi-sphere and consists of a surface detector (SD) array, plus three fluorescence detector (FD) stations overlooking the SD. The large field-of-view of an FD allows for reconstruction of the air-shower development in the atmosphere by imaging ultra-violet fluorescence light from atmospheric nitrogen excited by UHECRs. In estimation of the primary energy it is necessary to add to the calorimetric energy observed by the FD a “missing energy”, meaning the fraction of the primary energy that is not deposited by charged particles in the air. We report on the measurement of the missing energy from observed data collected by the TA FD and TA SD, independently of Monte Carlo simulations, using a technique pioneered by the Pierre Auger Observatory. We also address the effect on the energy scale attributed to fluorescence yield parameters.
Found in: ključnih besedah
Summary of found: ... UHECR, cosmic rays, energy spectrum...
Keywords: UHECR, cosmic rays, energy spectrum
Published: 29.04.2020; Views: 1530; Downloads: 56
.pdf Fulltext (4,74 MB)

33.
Composition Measurements via Depth of Airshower Maximum at the Telescope Array
W. Hanlon, J. P. Lundquist, 2018, published scientific conference contribution

Abstract: Telescope Array (TA) was designed to answer important questions about the UHECR flux with energies above 10^17 eV such as spectrum, arrival direction, and mass composition. Because the UHECR flux is rapidly falling in this energy region, TA’s large exposure makes it one of the few experiments in the world that can adequately explore these issues. Composition is particularly difficult to measure because mass can not be measured directly due to the low flux. TA’s multiple methods of observing UHECR induced air showers will be explained, as well as how composition can be measured by these methods. Good agreement among the different measurement techniques is found leading to greater confidence in measuring UHECR mass composition and a way to test and understand TA systematic uncertainties.
Found in: ključnih besedah
Summary of found: ...designed to answer important questions about the UHECR flux with energies above 10^17 eV such as...
Keywords: UHECR, cosmic rays, composition
Published: 29.04.2020; Views: 1537; Downloads: 70
.pdf Fulltext (758,27 KB)

34.
Energy-position correlation anisotropy of ultra-high energy cosmic rays with Telescope Array Data
J. P. Lundquist, published scientific conference contribution abstract

Abstract: Indication of an 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 besedah
Summary of found: ... UHECR, energy spectrum, anisotropy, magnetic deflection...
Keywords: UHECR, energy spectrum, anisotropy, magnetic deflection
Published: 29.04.2020; Views: 1576; Downloads: 0
.pdf Fulltext (1,84 MB)

35.
The Nature and Origin of Ultra-high Energy Cosmic Ray Particles
J. P. Lundquist, P.L. Biermann, 2016, published scientific conference contribution (invited lecture)

Abstract: We outline two concepts to explain Ultra High Energy Cosmic Rays (UHECRs), one based on radio galaxies and their relativistic jets and terminal hot spots, and one based on relativistic Super-Novae (SNe) or Gamma Ray Bursts (GRBs) in starburst galaxies, one matching the arrival direction data in the South (the radio galaxy Cen A) and one in the North (the starburst galaxy M82). The most likely identification of the origin of observed Gravitational Wave (GW) events is stellar binary black hole (BH) mergers in starburst galaxies such as M82 with the highest rate of star formation, so the highest far-infrared (FIR) luminosity, at the edge of the universe visible in 10 - 300 Hz GWs; at low heavy element abundance Zch the formation of stellar BHs extends to a larger mass range. A radio galaxy such as Cen A sequence of events involves first the merger of two Super-Massive Black Holes (SMBHs), with the associated ejection of low frequency GWs, then the formation of a new relativistic jet aiming into a new direction: ubiquitous neutrino emission follows accompanied by compact TeV photon emission, detectable more easily if the direction is towards Earth. The ejection of UHECRs is last. Both these sites are the perfect high energy physics laboratory: We have observed particles up to ZeV, neutrinos up to PeV, photons up to TeV, 30 - 300 Hz GW events, and hope to detect soon of order µHz to mHz GW events. Energy turnover in single low frequency GW events may be of order ∼1063 erg. How can we further test these concepts? First of all by associating individual UHECR events, or directional groups of events, with chemical composition in both the Telescope Array (TA) Coll. and the Auger Coll. data. Second by identifying more TeV to PeV neutrinos with recent SMBH mergers. Third by detecting the order < mHz GW events of SMBH binaries, and identifying the galaxies host to the stellar BH mergers and their GW events in the range up to 300 Hz. Fourth by finally detecting the formation of the first generation of SMBHs and their mergers, surely a spectacular discovery.
Found in: ključnih besedah
Summary of found: ...to explain Ultra High Energy Cosmic Rays ( UHECRs), one based on radio galaxies and their...
Keywords: UHECR, cosmic rays, anisotropy
Published: 29.04.2020; Views: 1435; Downloads: 97
.pdf Fulltext (372,72 KB)

36.
Cosmic Ray Shower Profile Track Finding for Telescope Array Fluorescence Detectors
J. P. Lundquist, 2016, published scientific conference contribution

Abstract: A simple cosmic ray track finding pattern recognition analysis (PRA) method for fluorescence detectors (FD) has been developed which significantly improves Xmax resolution and its dependence on energy. Events which have a clear rise and fall in the FD view contain information on Xmax that can be reliably reconstructed. Shower maximum must be extrapolated for events with Xmax outside the field of view of the detector, which creates a systematic dependence on the fitting function. The PRA method is a model and detector independent approach to removing these events, by fitting shower profiles to a set of triangles and applying limits on the allowable geometry.
Found in: ključnih besedah
Summary of found: ... UHECR, cosmic rays, fluorescence detector, track finding, pattern...
Keywords: UHECR, cosmic rays, fluorescence detector, track finding, pattern recognition
Published: 29.04.2020; Views: 1721; Downloads: 82
.pdf Fulltext (1,59 MB)

37.
Study of UHECR Composition Using Telescope Array's Middle Drum Detector and Surface Array in Hybrid Mode
J. P. Lundquist, 2016, published scientific conference contribution

Abstract: The seven year Telescope Array (TA) Middle Drum hybrid composition measurement shows agreement between Ultra-High Energy Cosmic Ray (UHECR) data and a light composition obtained with QGSJetII-03 or QGSJet-01c models. The data are incompatible with a pure iron composition, for all models examined, for energies log10(E/eV)>18.4. This is consistent with previous TA results. This analysis is presented using an updated version of the pattern recognition analysis (PRA) technique developed by TA.
Found in: ključnih besedah
Keywords: UHECR, cosmic rays, hybrid detection, composition
Published: 29.04.2020; Views: 1510; Downloads: 59
.pdf Fulltext (150,19 KB)

38.
Report of the Working Group on the Composition of Ultra-High Energy Cosmic Rays
J. P. Lundquist, M. Unger, 2016, published scientific conference contribution

Abstract: The atmospheric depth, Xmax, at which the particle number of an air shower reaches its maximum is a good indicator for the mass of the primary particle. We present a comparison of the energy evolution of the mean of Xmax as measured by the Telescope Array and Pierre Auger Collaborations. After accounting for the different resolutions, acceptances and analysis strategies of the two experiments, the two results are found to be in good agreement within systematic uncertainties.
Found in: ključnih besedah
Summary of found: ... UHECR, cosmic rays, composition...
Keywords: UHECR, cosmic rays, composition
Published: 29.04.2020; Views: 1738; Downloads: 55
.pdf Fulltext (329,86 KB)

39.
TARA: Forward-scattered radar detection of UHECR at the telescope array
J. P. Lundquist, J. Belz, 2013, published scientific conference contribution

Abstract: Increased event statistics will be required to definitively answer the question of the origin(s) of Ultra-High Energy Cosmic Rays (UHECR). Using current technologies however, achieving the necessary statistics may be financially and practically impossible. We describe the status and plans of the TARA project, an effort to detect Ultra-High-Energy Cosmic Rays by their forward scattered or “bistatic” radar signature. Bistatic radar holds promise as a new remote sensing technique for UHECR, without the duty cycle limitations of nitrogen fluorescence detectors. Such a technique could prove key in advancing the study of UHECR beyond the constraints of the current generation of cosmic ray observatories. TARA consists of a low-VHF television transmitter illuminating the air above the Telescope Array (TA), and a set of radio receivers on the far side of TA approximately 50 km distant from the transmitter. We have collected radar data since April 2011 using a 2 kW transmitter at 54.1 MHz. Recently, we received permission to increase our broadcast power to 40 kW and our effective radiated power (ERP) to 6 MW. On the receiver end, we are employing software-defined radio receivers and developing real-time trigger algorithms based on the expected air shower radar echo. In addition to presenting an overview of the project status and future plans, we will present the most recent results of searches for coincidences between radar echoes and Telescope Array air shower events.
Found in: ključnih besedah
Keywords: UHECR, cosmic rays, radar detection
Published: 29.04.2020; Views: 1610; Downloads: 67
.pdf Fulltext (623,59 KB)

40.
Search for ultra-high-energy neutrinos with the Telescope Array surface detector
Mitsuhiro Abe, R. U. Abbasi, T. Abu-Zayyad, M. Allen, R. Azuma, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, Jon Paul Lundquist, 2020, original scientific article

Abstract: We present an upper limit on the flux of ultra-high-energy down-going neutrinos for E > 10^18 eV derived with the nine years of data collected by the Telescope Array surface detector (05-11-2008– 05-10-2017). The method is based on the multivariate analysis technique, so-called Boosted Decision Trees (BDT). Proton-neutrino classifier is built upon 16 observables related to both the properties of the shower front and the lateral distribution function.
Found in: ključnih besedah
Summary of found: ...neutrinos, pattern recognition, UHECR, cosmic rays...
Keywords: neutrinos, pattern recognition, UHECR, cosmic rays
Published: 29.04.2020; Views: 1679; Downloads: 57
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