Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session R11: Telescope ArrayFocus
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Sponsoring Units: DAP Chair: Gordon Thomson, University of Utah Room: 250C |
Monday, April 18, 2016 10:45AM - 10:57AM |
R11.00001: Observation of Ultra High Energy Cosmic Rays by the Telescope Array Observatory John Matthews The Telescope Array cosmic ray observatory inhabits about 700 sq km of central Utah desert \textasciitilde 3 hours south of Salt Lake City and is a hybrid cosmic ray detector consisting of fluorescence telescopes observing the sky above an array of scintillator detectors which sample the charged particle density from cosmic ray induced extensive air showers. It is used to study the energy spectrum, chemical composition and anisotropy of cosmic rays. Recently we have extended the energy reach lower so that we observe over more than four decades of energy. We are also in the process of extending the Telescope Array aperture by a factor of 4 to better understand a ``hot spot'' in the northern sky which could turn out be the first observed source of ultra high energy cosmic rays. The experiment and its measurements will be introduced. [Preview Abstract] |
Monday, April 18, 2016 10:57AM - 11:09AM |
R11.00002: Study of High-Energy Particles Correlated with Lightning at Utah's Telescope Array Cosmic Ray Observatory John Belz It is known that x-ray and gamma radiation is emitted by lightning. This phenomenon has been observed by both ground-based and spaced-based detectors. Recently, cosmic ray physicists studying data collected by the 700 square-kilometer Telescope Array Surface Detector (TASD) have observed energetic elementary particles in coincidence with lightning strikes. A subset of these events contain reconstructable ``showers'' which point back to the particles' origin in the Earth's atmosphere. This implies that the energetic radiation may for the first time be traced to its source within the lightning strike. The Lightning Mapping Array (LMA) pioneered at Langmuir Laboratories is the ideal instrument to couple with the TASD in order to perform these studies. These LMA's consist of roughly ten VHF detectors spread over hundreds of square kilometers, and detect impulsive radiation from lightning. The sources of these impulses may be reconstructed and used to create a 3-dimensional GPS-timed reconstruction of a lightning strike. The merger of TA and LMA is also the ideal instrument to search for evidence of a more speculative - but more profound - connection between particle astrophysics and climate: The seeding of lightning strikes by cosmic ray air showers. [Preview Abstract] |
Monday, April 18, 2016 11:09AM - 11:21AM |
R11.00003: A measurement of Vertical Aerosol Optical Depth at the Telescope Array experiment Jihee Kim We will present a technique for measuring the Vertical Aerosol Optical Depth (VAOD), a critical parameter for correcting atmospheric attenuation. This technique uses a vertical laser beam fired from the Central Laser Facility, located equidistance from the Telescope Array fluorescence telescope stations. Using laser beam events seen by the stations, we analyze the amount of light lost from aerosols hourly each night. From those measurements, we estimate the nightly VAOD. We find that the event-by-event uncertainty in the VAOD is $\pm$ 0.007, which is $\pm$ 3$\%$ in energy at distance 21 km. Furthermore, by looking at the same laser events seen by different stations, we can measure the $<$VAOD$>$ to $\pm$ 0.003, which is $\pm$ 1.5$\%$ in energy at distance 21 km. [Preview Abstract] |
Monday, April 18, 2016 11:21AM - 11:33AM |
R11.00004: Anisotropy of Ultra-High Energy Cosmic Rays Using Minimal Assumption Energy-Position Correlation with Telescope Array Data Jon Paul Lundquist Presented is the result of an Ultra-High Energy Cosmic Ray (UHECR) anisotropy search using both incident particle energy and apparent originating position in the sky - 7 years of Telescope Array (TA) surface detector (SD) data are used. Deflection from sources of charged cosmic ray particles, by unknown intervening magnetic fields, complicate anisotropic density searches but are expected to create correlations between energy and position. A general method for examining these correlations should include as few assumptions as possible and be robust against background noise events. Outlined is an energy-position correlation anisotropy search with no assumptions made regarding source distribution, event composition or magnetic field configurations. This is done using an unbinned energy-opening angle rank correlation. [Preview Abstract] |
Monday, April 18, 2016 11:33AM - 11:45AM |
R11.00005: Searches for Anisotropy of Cosmic Rays with the Telescope Array Robert Cady With over seven years of data from the TA surface detector array, we will present the results of various searches for anisotropies in the arrival direction of cosmic rays, including an update of the hotspot above 57 EeV. [Preview Abstract] |
Monday, April 18, 2016 11:45AM - 11:57AM |
R11.00006: Search of EeV Protons of Galactic Origin. Dmitri Ivanov Cosmic rays in 1 to 3 EeV range have been shown to have a light, most likely protonic, mass composition. To establish their origin, one can search for anisotropy in their arrival directions: extragalactic protons should be isotropic, but those originating within the Galaxy should be concentrated along the galactic plane, and there should be a shortage of events near the galactic anticenter. Guided by the latest models of the galactic magnetic field, which indicate these effects, we search for the anisotropy in the data collected by the surface detector of the Telescope Array experiment. [Preview Abstract] |
Monday, April 18, 2016 11:57AM - 12:33PM |
R11.00007: Recent results from the Telescope Array Experiment Invited Speaker: Rasha Abbasi The Telescope Array (TA) is the largest ultrahigh energy cosmic rays detector in the northern hemisphere. TA is a hybrid detector comprised of three air fluorescence stations and a large surface array consisting of 507 scintillator counters. Each of the three fluorescence stations, located at the periphery of the ground array, views 108 degrees in azimuth and up to 30 degrees in elevation. The surface detectors are arranged in a square grid of 1.2 km spacing, covering over 700 square kilometers. TA has collected more than seven years of data. In this talk, we will present some of the main results on the cosmic rays composition and energy spectrum obtained by TA and its low energy extension (TALE). Finally, we will present our results from the search for arrival direction anisotropy, including the observed large excess of events at the highest energies, seen in the region of the northern sky centered on Ursa Major. Based on the current results, the “hot spot” in particular, TA is pursuing the expansion of the surface array to four times its current size. [Preview Abstract] |
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