Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 57, Number 11
Friday–Saturday, October 26–27, 2012; Socorro, New Mexico
Session B2: Ultra High Energy Astrophysics |
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Chair: Steven Wasserbaech, Utah Valley University Room: Macey Center Galena |
Friday, October 26, 2012 10:40AM - 10:52AM |
B2.00001: The water Cherenkov detectors of the HAWC Observatory Megan Longo, Miguel Mostafa The High Altitude Water Cherenkov (HAWC) observatory is a very high-energy gamma-ray detector which is currently under construction at 4100 m in Sierra Negra, Mexico. The observatory will be composed of an array of 300 Water Cherenkov Detectors (WCDs). Each WCD consists of a 5 m tall by 7.3 m wide steel tank containing a hermetically sealed plastic bag, called a bladder, which is filled with 200,000 liters of purified water. The detectors are each equipped with four upward-facing photomultiplier tubes (PMTs), anchored to the bottom of the bladder. At Colorado State University (CSU) we have the only full-size prototype outside of the HAWC site. It serves as a testbed for installation and operation procedures for the HAWC observatory. The WCD at CSU has been fully operational since March 2011, and has several components not yet present at the HAWC site. In addition to the four HAWC position PMTs, our prototype has three additional PMTs, including one shrouded (dark) PMT. We also have five scintillator paddles, four buried underneath the HAWC position PMTs, and one freely moving paddle above the volume of water. These extra additions will allow us to work on muon reconstruction with a single WCD. We will describe the analysis being done with the data taken with the CSU prototype, its impact on the HAWC detector, and future plans for the prototype. [Preview Abstract] |
Friday, October 26, 2012 10:52AM - 11:04AM |
B2.00002: Calibration of PMTs for the HAWC Observatory using Afterpulsing Michael Gussert I present an alternative method to calibrate the PMTs of the High Altitude Water Cherenkov (HAWC) observatory using afterpulsing. Currently, the PMT calibration is done with a laser system. PMTs are exposed to laser pulses of varying intensities to determine the time over threshold (TOT) of the PMT responses, and then the number of photo-electrons (PEs). In the proposed alternative method, the number of afterpulses (AP) produced by a PMT is used to estimate the number of PEs at the photocathode. I will present preliminary results on the relationship between these two values, the extrapolation to higher AP values to produce a calibration curve of AP vs PE, and finally, the statistical occupancy of afterpulsing as a function of the TOT value to obtain the final calibration curve of PEs as a function of TOT. [Preview Abstract] |
Friday, October 26, 2012 11:04AM - 11:28AM |
B2.00003: The Telescope Array: Current status and future prospects Invited Speaker: Benjamin Stokes The Telescope Array is the largest cosmic ray observatory in the Northern Hemisphere. The principal components of the observatory were commissioned in May 2008 with the aim of discovering the composition and origins of the ultra-high energy cosmic rays which comprise the upper terminus of the astroparticle spectrum. Today, the Telescope Array collaboration serves as a pioneer in the analysis of observational cosmic ray data while continuing to accumulate observation time, expanding its observational capabilities, and serving as a testbed for novel cosmic ray detection techniques. [Preview Abstract] |
Friday, October 26, 2012 11:28AM - 11:40AM |
B2.00004: Physics and Fluorescence Detection of Cosmic Ray Air Showers with Energies Between 10$^{16.5}$ eV and 10$^{19}$ eV Zachary Zundel The Telescope Array (TA) Experiment has been observing cosmic ray air showers at energies above 10$^{18}$ eV since 2008. The TA detectors include fluorescence telescopes that look between 3and 33in elevation and a surface array consisting of 507 plastic scintillators layed out on a 1.2km square grid. The TA collaboration is currently installing fluorescence telescopes that look between 33and 59in elevation and starting the construction of a graded infill array of surface detectors spaced at 400m and 600m. 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 of TALE, and report on the progress of the new fluorescence telescopes. [Preview Abstract] |
Friday, October 26, 2012 11:40AM - 11:52AM |
B2.00005: Energy Spectrum and Composition of Ultra High Energy Cosmic Ray Showers Using Hybrid Analysis from Telescope Array Monica Allen, Tareq Abu-Zayyad, Benjamin T. Stokes The Telescope Array studies ultra high energy cosmic rays using a hybrid detector. Fluorescence telescopes measure the longitudinal development of the extensive air shower generated by a primary cosmic ray particle, while scintillator detectors measure the lateral distribution of secondary particles that hit the ground. The Middle Drum (MD) fluorescence telescope consists of 14 refurbished telescopes from the High Resolution Fly's Eye experiment (HiRes), providing a direct link back to the HiRes experiment and data. Using the scintillator detector data in conjunction with the MD 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 will be presented. In addition, a MD hybrid composition study was also performed, and results will be shown. [Preview Abstract] |
Friday, October 26, 2012 11:52AM - 12:04PM |
B2.00006: Testing the Sensitivity of the Pierre Auger Observatory in the Direction of AGN Levi Patterson, Eric Mayotte, Alexandra Woolman, Michael Bratton, Lawrence Wiencke We present a technique for measuring the absolute timing of the Pierre Auger Observatory. The technique uses laser shots from the Central Laser Facility that are aimed in the direction of ten astrophysical objects of interest. Using two years of this data we have accumulated sky maps of reconstructed laser direction in galactic coordinates. The data clusters around the direction of the target objects. From reconstructions of these laser shots we are also able to measure the absolute pointing direction and the angular resolution of the Pierre Auger Observatory using multi-eye FD hybrid data. This technique is planned for use with the JEM-EUSO project. This technique was developed by undergraduate physics majors at the Colorado School of Mines for their senior design projects. [Preview Abstract] |
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