Bulletin of the American Physical Society
2011 Annual Meeting of the Four Corners Section of the APS
Volume 56, Number 11
Friday–Saturday, October 21–22, 2011; Tuscon, Arizona
Session M5: Astrophysical Detectors: Techniques and Measurements |
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Chair: Drew Milsom, University of Arizona Room: UA Student Union Presidio |
Saturday, October 22, 2011 11:10AM - 11:22AM |
M5.00001: A Water Cherenkov Detector prototype for the HAWC Gamma-Ray Observatory Megan Longo, Miguel Mostafa, Francisco Salesa Greus, David Warner A full-size Water Cherenkov Detector (WCD) prototype for the High Altitude Water Cherenkov (HAWC) gamma-ray Observatory was deployed, and is currently being operated at Colorado State University (CSU). The HAWC Observatory will consist of 300 WCDs at the very high altitude (4100m) site in Sierra Negra, Mexico. Each WCD will have 4 baffled upward-facing Photomultiplier Tubes (PMTs) anchored to the bottom of a self made multilayer hermetic plastic bag containing 200,000 liters of purified water, inside a 5m deep by 7.3m diameter steel container. The full size WCD at CSU is the only full size prototype outside of the HAWC site. It is equipped with seven HAWC PMTs and has scintillators both under and above the volume of water. It has been in operation since March 1, 2011. This prototype also has the same laser calibration system that the detectors deployed at the HAWC site will have. The CSU WCD serves as a testbed for the different subsystems before deployment at high altitude, and for optimizing the location of the PMTs, the design of the light collectors, deployment procedures, etc. Simulations of the light inside the detectors and the expected signals in the PMTs can also be benchmarked with this prototype. [Preview Abstract] |
Saturday, October 22, 2011 11:22AM - 11:34AM |
M5.00002: Cosmic Ray in the Northern Hemisphere: Results from the Telescope Array Experiment Charles Jui The Telescope Array (TA) is the largest ultrahigh energy (UHE) cosmic ray observatory in the northern hemisphere. TA is a hybrid experiment with a unique combination of fluorescence detectors and a stand-alone surface array of scintillation counters. We will present the spectrum measured by the surface array alone, along with those measured by the fluorescence detectors in monocular, hybrid, and in stereo mode. The composition results from stereo TA data will be discussed. Our report will also include results from the search for correlations between the pointing directions of cosmic rays, seen by the TA surface array, with AGN's. [Preview Abstract] |
Saturday, October 22, 2011 11:34AM - 11:46AM |
M5.00003: Comparison between Raman Backscatter and Elastic Side Scatter Methods for Measuring Aerosol Optical Depth Michael Coco, David Starbuck, Lawrence Wiencke Raman backscatter LIDAR is the standard method in atmospheric physics for measuring atmospheric aerosol optical depth profiles. In contrast, high energy cosmic ray observatories, including HiRes and Pierre Auger, measure this parameter using elastic side scattering. We present a comparison between the techniques using 200 hours of data collected at the Pierre Auger Colorado R\&D site. Data was acquired by two detectors that measure scattered light from a 355nm pulse laser fired vertically into the atmosphere. A Raman backscatter detector was located at the base of the laser. A simplified florescence detector was located 40km from the laser. Alternate LIDAR signal processing methods will also be discussed. [Preview Abstract] |
Saturday, October 22, 2011 11:46AM - 11:58AM |
M5.00004: Energy Spectrum of Ultra High Energy Cosmic Ray Showers Using Hybrid Analysis from Telescope Array Monica Allen, Tareq Abu-Zayyad, Benjamin 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 method for determining the spectrum will be described. The event selection and reconstruction process, along with the Monte Carlo simulation used for calculating the detector aperture and exposure will also be discussed. Detector resolutions and comparisons between Monte Carlo and data distributions of key variables that contribute to the aperture will be shown to validate the simulation. Finally, the resulting hybrid spectrum obtained from the Middle Drum fluorescence detector will be presented. [Preview Abstract] |
Saturday, October 22, 2011 11:58AM - 12:10PM |
M5.00005: Absolute and Multiwavelength calibration of the Pierre Auger Observatory fluorescence detectors Ben Gookin, Jeffrey Brack, Alexei Dorofeev, John Harton, Yevgeniy Petrov, Robert Cope The methods and results of the calibration of the Pierre Auger Observatory fluorescence detectors will be presented. Two methods are shown, an absolute calibration at a single UV wavelength and a relative calibration at several UV wavelengths. Both techniques use a uniform 2.5m diameter light source and are an end-to-end measurement of all the detector components. This technique calibrates the combined effect of each component in a single measurement. 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 multiwavelength calibration. [Preview Abstract] |
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