Bulletin of the American Physical Society
Fall 2009 Meeting of the Four Corners Section of the APS
Volume 54, Number 14
Friday–Saturday, October 23–24, 2009; Golden, Colorado
Session C1: Astroparticle Symposium II: UHE Cosmic Rays: Spectrum and Composition |
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Chair: Fred Sarazin, Colorado School of Mines Room: Green Center 210N |
Friday, October 23, 2009 3:40PM - 3:52PM |
C1.00001: The HiRes Stereo Measurement of the UHECR Spectrum Douglas Bergman The High Resolution Fly's Eye (HiRes) Experiment has measured the ultra-high energy cosmic ray (UHECR) energy spectrum using a stereo technique combining the observations of its two sites to provide very accurate determination of extensive air shower geometry. The spectrum will be shown, along with previous measurements in monocular mode, fits to all the spectra to show the energy of the observed GZK suppression and a discussion of systematic errors. [Preview Abstract] |
Friday, October 23, 2009 3:52PM - 4:04PM |
C1.00002: Measurement of the Cosmic Ray Energy Spectrum with the Pierre Auger Observatory Lawrence Wiencke The Pierre Auger Observatory has measured the cosmic ray energy spectrum above 10^18 eV using several techniques. The spectrum can be described by a broken power-law of index 3.3 below the ankle which is measured at lg(Eankle/eV) = 18.6. Above the ankle the spectrum is described by a power-law / E-2.6 and a flux suppression with lg(E1/2/eV) = 19.6 This talk will summarize the methods and results. [Preview Abstract] |
Friday, October 23, 2009 4:04PM - 4:16PM |
C1.00003: Cosmic Ray Composition Studies with the High Resolution Fly's Eye John Belz The depth of shower maximum or $X_{max}$ of extensive airshowers is a sensitive probe of the chemical composition of ultra-high energy cosmic rays. Both the evolution of mean $X_{max}$ with energy and the width of the $X_{max}$ distribution can provide clues as to the species of the particles initiating the airshowers. Here, we report the results of composition studies using $X_{max}$ with data collected in stereoscopic mode by the High-Resolution Fly's Eye observatory. The HiRes data are best explained by a predominantly protonic composition above 1.6~EeV. [Preview Abstract] |
Friday, October 23, 2009 4:16PM - 4:28PM |
C1.00004: Measurement of the Average Depth of Shower Maximum and its Fluctuations with the Pierre Auger Observatory Megan Longo We present a measurement of the rate of change of the depth of shower maximum with energy using data from the Pierre Auger Observatory. We introduce an event selection that assures an unbiased and high quality data sample. The analysis of these results will lead to further understanding of the hadronic interaction models and the mass composition of cosmic rays at ultra high energies. [Preview Abstract] |
Friday, October 23, 2009 4:28PM - 4:40PM |
C1.00005: Programs that Think. Programs that Love. Programs that Identify the Composition of Ultra High Energy Cosmic Rays. Michael Gussert The use of evolutionary neural network techniques to identify the composition of ultra high energy cosmic rays is being explored. The air shower parameters measured by the Pierre Auger Observatory cannot easily identify the composition of the shower primary. However, Artificial Neural Networks (ANNs) can be evolved to learn the dependence of these parameters on the primary composition. Once completed, such a network would then be able to estimate the composition of the primary for a given air shower. A modified version of the Symbiotic, Adaptive, Neuro-Evolution (SANE) algorithm is being studied to allow neurons within the network to specialize in a specific aspect of the dependence. [Preview Abstract] |
Friday, October 23, 2009 4:40PM - 4:52PM |
C1.00006: Preliminary results from a new Auger fluorescence detector drum calibration light source Alexei Dorofeev, Jeffrey Brack, Robert Cope, Ben Gookin, John Harton, Jan Kempinger, Yevgeniy Petrov A new revision of electronics for Auger Observatory fluorescence detector drum calibration is in final completion stage now. The drum light source design is based on a new 365nm high power LED produced by Nichia. In this report we will present preliminary results on a spectrum of the drum light source and the influence of ambient temperature, pulse rate and pulse current amplitude on the drum spectrum. [Preview Abstract] |
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