Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 58, Number 12
Friday–Saturday, October 18–19, 2013; Denver, Colorado
Session M5: Cosmic Rays |
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Chair: Johanthan Ormes, University of Denver Room: 251 |
Saturday, October 19, 2013 2:15PM - 2:39PM |
M5.00001: Cosmic Rays Invited Speaker: John Matthews |
Saturday, October 19, 2013 2:39PM - 2:51PM |
M5.00002: Fluoresence Detection of of Cosmic Ray Air Showers Between $10^{16.5}$ eV and $10^{19}$ eV with the Telescope Array Low Energy Extension (TALE) Zachary Zundel, Jeremy Smith, Stan Thomas, Dmitri Ivanov, John N Matthews, Charlie Jui The Telescope Array Experiment has been observing cosmic ray air showers at energies above $10^{18}$ eV since 2008. TA operates three Fluorescence Detector (FD) sites, with telescopes that observe 3-31 deg in elevation. The FD sites are located at the periphery of a surface array of 507 scintillation counters covering 700 $km^{2}$, with 1.2km spacing. The TA Collaboration has completed building a low-energy extension at its Middle drum FD site. Ten new telescopes currently observe between 33 and 51 degrees in elevation. A graded ground array of between 400 and 600m will be placed in front of the TALE FD. We have already observed scattered light from the central laser (CLF) and coincident events with the Middle Drum FD. By 9/2013, all ten telescopes were instrumented with a central timing system. Additionally, the first 35 scintillator counters have been deployed by helicopter. With these upgrades, the physics threshold of TA will be lowered to $10^{16.5}$ eV. The TA Low Energy Extension(TALE) will explore the energy regime corresponding to that of the LHC in center-of-mass frame. This is also the range where the transition from galactic to extra- galactic cosmic ray flux is suspected to occur. We will give a brief overview of the physics, and report on the progress of TALE. [Preview Abstract] |
Saturday, October 19, 2013 2:51PM - 3:03PM |
M5.00003: Calibrating a large diameter light source and multi-wavelength calibration of the Pierre Auger Observatory fluorescence detectors Ben Gookin, Jeff Brack, Alexei Dorofeev, John Harton, Yevgeniy Petrov Calibration of the Pierre Auger Observatory fluorescence detectors is performed using a low intensity uniform 2.5m diameter light source which allows for an end-to-end measurement of all detector components that calibrates the combined effect of each component in a single measurement. There are two fluorescence detector calibrations that utilize the 2.5m diameter light source, absolute calibration at a single UV wavelength and a relative calibration at several UV wavelengths. Recent improvements in technique and equipment have increased calibration reliability and improved uncertainties. We discuss these improvements here, including digital control and monitoring of LED pulses, a technique using the $1/r^2$ attenuation of light in the calibration of this low intensity light source, and the use of a monochromator to pick out single wavelengths in a broad UV range to perform the relative calibration. Preliminary data on the relative calibration using the monochromator setup will be presented, along with the effect of this calibration on the reconstructed energy of simulated showers using the Pierre Auger Observatory fluorescence detector simulation. [Preview Abstract] |
Saturday, October 19, 2013 3:03PM - 3:15PM |
M5.00004: TALE Hybrid Simulation and Analysis Dmitri Ivanov The Telescope Array (TA) is the largest cosmic ray detector in the Northern hemisphere that observes cosmic rays of primary energies above 10$^{18}$ eV. The Telescope Array Low-energy Extension (TALE) is built to provide additional observational capability for primary energies between 3 x 10$^{16}$ eV and 10$^{18}$ eV. TALE is a hybrid detector which consists of ten additional fluorescence telescopes situated at the TA Middle Drum (TAMD) fluorescence detector site with 30 to 57 degree sky coverage in elevation, and an infill surface array of 105 plastic scintillation counters with variable 400 to 600-meter spacing. Together with the original TAMD detector, this yields a combined sky coverage of 112 degrees in azimuth and 3 to 57 degrees in elevation for the Middle Drum site. In this presentation, we describe the simulation and reconstruction techniques used for analyzing the TALE data. [Preview Abstract] |
Saturday, October 19, 2013 3:15PM - 3:27PM |
M5.00005: Observations of the Small Scale Cosmic Ray Anisotropy by HAWC Ahron Barber HAWC, the High Altitude Water Cherenkov Observatory, is being built on the slopes of Sierra Negra in the Pico de Orizaba Mexican National Park. This gamma-ray and cosmic-ray observatory is at 4100m A.S.L. and is a second generation water Cherenkov detector. Previously, the Milagro observatory (HAWC's predecessor) and the ARGO and Tibet observatories have detected anisotropy on angular scales of $\sim$10-20 degrees with amplitudes of $\sim10^{-4}$ in the arrival directions of cosmic rays. This small-scale anisotropy has no predicted origin. Cosmic rays in the TeV energy range have gyroradii less than 0.01 pc and their arrival directions should be isotropic, as there are no known sources within this distance. Recent theories suggest that the anisotropy could be due to galactic and/or heliospheric effects. HAWC-30, the first 10\% of HAWC, began operations on January 1st, 2013 and was able to detect the small-scale cosmic ray anisotropy regions. In addition, HAWC-95, which started operations in mid-June 2013, was able to detect the anisotropy after $\sim$1.5 months. [Preview Abstract] |
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