Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session R9: Cosmic Rays I |
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Sponsoring Units: DAP Chair: Pierre Sokolsky, University of Utah Room: Marriott Tampa Waterside Room 5 |
Monday, April 18, 2005 10:45AM - 10:57AM |
R9.00001: Measurement of the HiRes Stereo Composition Brian Connolly Extensive air showers are induced when ultra-high energy cosmic ray particles enter the Earth's atmosphere. The distribution of depths where the number of particles in the air showers reach a maximum (defined as $X_{max}$) can be used to measure the composition. We present a method of directly measuring the flux of various hypothesized compositions by comparing Monte Carlo calculations of $X_{max}$ with the distribution of $X_{max}$ for data. [Preview Abstract] |
Monday, April 18, 2005 10:57AM - 11:09AM |
R9.00002: A deconvolution technique, to measure proton cross-section at ultra-high energies using cosmic ray data. Konstantin Belov Extensive air showers are induced when ultra-high energy cosmic ray particles enter the earth atmosphere. The distribution of the depth of the air shower maxima can be used to measure the p-air inelastic cross-section. We propose a novel deconvolution measurement technique. We use Monte Carlo simulations to evaluate the technique, and the statistical and systematic errors. [Preview Abstract] |
Monday, April 18, 2005 11:09AM - 11:21AM |
R9.00003: Search for Correlated High Energy Cosmic Ray Events with CHICOS B. E. Carlson, E. Brobeck, C. J. Jillings, M. B. Larson, T. W. Lynn, R. D. McKeown, James E. Hill, B. J. Falkowski, R. Seki, J. Sepikas, G. B. Yodh We present the results of a search for time correlations in high energy cosmic ray data (primary $E > 10^{14}$~eV) collected by the California HIgh school Cosmic ray ObServatory (CHICOS) array. Data from 60 detector sites spread over an area of 400~km$^2$ were studied for evidence of isolated events separated by more than 1~km with coincidence times ranging from 1~$\mu$sec up to 1~second. The results are consistent with the absence of excess coincidences except for a $2.9 \sigma$ excess observed for coincidence times less than 10~$\mu$sec. We report upper limits for the coincidence probability as a function of coincidence time. [Preview Abstract] |
Monday, April 18, 2005 11:21AM - 11:33AM |
R9.00004: Lateral and Time Distributions of Extensive Air Showers for CHICOS C.J. Jillings, E.G. Brobeck, B.E Carlson, T.W. Lynn, R.D. McKeown, D. Wells, K.C. Chan, J. Hill, B. Falkowski, R. Seki, J. Sepikas We report results of a series of detailed Monte-Carlo calculations to determine the density and arrival-time distribution of charged particles in extensive air showers. We have parameterized both distributions as a function of distance from the shower axis, energy of the primary cosmic-ray proton, and incident zenith angle. Muons and electrons are parameterized separately. These parameterizations can be easily used in maximum-likelihood reconstruction of air showers. Calculations were performed for primary energies between $10^{18}$ and $10^{21}eV$ and zenith angles out to approximately $50^{\circ}$. The calculations are appropriate for the California High School Cosmic Ray Observatory: a 400 $\mbox{km}^{2}$ array of scintillation detectors in Los Angeles county. The average elevation of the array is approximately 250 meters above sea level. Currently 64 of 90 sites are operational. The array will be completed this year. We thank the NSF, the CURE program at the Jet Propulsion Laboratory, the SURF program at Caltech, and the Chinese University of Hong Kong. [Preview Abstract] |
Monday, April 18, 2005 11:33AM - 11:45AM |
R9.00005: Status and Physics Objectives of the Pierre Auger Observatory Matthias Leuthold The Pierre Auger Observatory is designed to explore the upper end of cosmic ray energy spectrum, particles with energies exceeding $10^{19}$~eV. The detector consists of two complementary components: an air shower array of 1600 water Cherenkov detectors, and a fluorescence detector consisting of 24 wide-angle Schmidt telescopes. The surface detectors are distributed across an area of 3000 km$^2$, sampling the air shower particles that reach the ground. The telescopes are positioned at four sites around the ground array and observe the fluorescence light emitted by the air shower as it develops in the atmosphere.The simultaneous observation with two independent sub-detectors allows for a reduction of the systematic uncertainties. In this talk the status of construction and the main physics goals of the Pierre Auger Observatory will be reviewed. [Preview Abstract] |
Monday, April 18, 2005 11:45AM - 11:57AM |
R9.00006: The Surface Detector Array of the Pierre Auger Observatory Aaron Chou The Pierre Auger cosmic ray observatory is being constructed in Malargue, Argentina with the goal of probing the origins and physics of the highest energy cosmic rays. The rapidly growing surface detector array of the observatory has been in continuous operation for more than one year, already accumulating a large physics data set . In this talk we discuss the calibration and operation of the water Cherenkov surface detectors, and the reconstruction and analysis of the cosmic ray shower data. [Preview Abstract] |
Monday, April 18, 2005 11:57AM - 12:09PM |
R9.00007: The Fluorescence Detector of the Pierre Auger Observatory Pablo Bauleo The Auger fluorescence detector is optimized to measure showers with energy above 10$^{19}$~eV over an area of 3000 km$^{2}$. The design calls for a system capable of detect a few tens of Watts of ultraviolet light produced more than 25 km away. To achieve that, large aperture mirrors and a extremely sensitive light detector system are required. This paper describes the telescope optics, light detection system, as well as calibration techniques and reconstruction algorithms. Examples of reconstructed events will be shown. [Preview Abstract] |
Monday, April 18, 2005 12:09PM - 12:21PM |
R9.00008: Hybrid Performance of the Pierre Auger Observatory Miguel Mostafa The Pierre Auger Observatory detects ultra-high energy cosmic rays combining two complementary air shower techniques. The designed observation in coincidence of particles at ground and the associated fluorescence light generated in the atmosphere is achieved with a large array of water Cherenkov detectors coupled with air fluorescence detector sites. The combination of fluorescence and ground array measurements provides reconstruction of the shower axis geometry with unprecedented accuracy, which in turn yields improvements in measurements of all other observables. Timing information from even a single surface detector can much improve the geometric reconstruction, thus lowering the energy threshold for hybrid events to well below the surface detector design threshold of 10~EeV. In these hybrid events, the simultaneous independent measurements of longitudinal and transverse shower observables via the two techniques give powerful crosschecks on the data analysis and better control over systematic uncertainties in the energy measurement. In this paper the hybrid reconstruction approach and its performance are described. [Preview Abstract] |
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R9.00009: Search for Point Sources of Ultra-High Energy Cosmic Rays Brian Connolly We present the results of a search for cosmic ray point sources at energies above $4.0\times 10^{19}$\,eV in the combined data sets recorded by the AGASA and HiRes stereo experiments. The analysis is based on a maximum likelihood ratio test using the probability density function for each event rather than requiring an a priori choice of a fixed angular bin size. No statistically significant clustering of events consistent with a point source is found. [Preview Abstract] |
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