Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session C11: Cosmic Ray Measurements, Anisotropies and Propagation |
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Sponsoring Units: DAP Chair: Mikhail Medvedev, University of Kansas Room: Garden 2 |
Saturday, April 30, 2011 1:30PM - 1:42PM |
C11.00001: Proton and Helium Spectra from the Third CREAM Flight Young Soo Yoon The balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment measures the composition and energy spectra of high energy cosmic rays. CREAM utilizes a tungsten/scintillator calorimeter to determine energy and identifies particle charge with a silicon pixel detector. To date the CREAM payload has already flown six times over Antarctica. During the 2007-2008 Antarctic season, it flew for 29 days on its third flight, which accumulated more data at lower energies than the two previous flights. This was due to its improved electronics readout range and reduced pedestal noise level. Also, the third flight has about twice as many events in the energy range above $\sim $10 TeV as the first flight. The increased data reduced the statistical uncertainties of measured elemental energy spectra. The proton and helium fluxes from the CREAM-III flight will be presented. [Preview Abstract] |
Saturday, April 30, 2011 1:42PM - 1:54PM |
C11.00002: A Time Dependent Analysis of the Interference between the Solar and the Sidereal Anisotropies using the 59 String IceCube Detector Craig Price, Rasha Abbasi, Paolo Desiati IceCube is a kilometer scale neutrino observatory that collected 34 billion cosmic ray induced muon events from May 2009 to May 2010 in the 59-string configuration, or 324 days of lifetime. These events, which are background for neutrino searches, are sufficient to observe anisotropies in cosmic ray arrival direction with amplitude of about $10^{-4}$. We present evidence that the leakage of the large-scale sidereal anisotropy into the solar reference frame explains all distortions of the solar dipole (due to the Earth's revolution around the Sun) throughout the year. This suggests that in the energy range IceCube is sensitive to, there are exactly two cosmic ray anisotropies, the sidereal anisotropy and the solar dipole. [Preview Abstract] |
Saturday, April 30, 2011 1:54PM - 2:06PM |
C11.00003: Observation of a cosmic ray anisotropy in the southern sky with IceCube Marcos Santander IceCube is a kilometer-scale neutrino telescope currently in the final stages of its construction at the geographic South Pole. When complete, the detector will consist of 5160 Digital Optical Modules (DOMs) deployed at depths between 1.5 and 2.5 km over an instrumented volume of 1 km$^3$. Although the main scientific goal of IceCube is the detection of astrophysical neutrinos, it also detects tens of billions of muons per year, which are produced by the interaction of TeV cosmic rays with the Earth's atmosphere. Such a high level of statistics has allowed us to probe, for the very first time, the southern sky for anisotropies in the arrival direction of cosmic rays in this energy range. We report on the discovery of a cosmic ray anisotropy over a wide range of angular scales in the sky, which is consistent with anisotropies previously observed in the northern sky by other experiments. [Preview Abstract] |
Saturday, April 30, 2011 2:06PM - 2:18PM |
C11.00004: Anisotropy energy dependence of the cosmic ray arrival direction with IceCube Rasha Abbasi, Paolo Desiati In this work we present an update on the previously reported anisotropy in the arrival direction of cosmic rays using data from the IceCube detector. The data used in this analysis were collected from May 2009 to May 2010 with 59 deployed strings. We also report on the energy dependence of this anisotropy at median energies per cosmic ray particle of 20 TeV and 400 TeV. The results are supported by the observation of the solar diurnal anisotropy measurement expected from the revolution of the Earth around the Sun. It is also supported by the absence of the signal in the anti-sidereal time. Study of the anisotropy evolution in the energy region greater than 100 TeV can provide us an insight to the origin and propagation of cosmic rays. [Preview Abstract] |
Saturday, April 30, 2011 2:18PM - 2:30PM |
C11.00005: Constraints on Cosmic-Ray Propagation Models from a Global Bayesian Analysis Igor Moskalenko, Roberto Trotta, Gudlaugur J\'ohannesson, Troy Porter, Roberto Ruiz de Austri, Andrew Strong Research in many areas of modern physics such as, e.g., indirect searches for dark matter and particle acceleration in SNRs rely on studies of cosmic rays (CRs) and associated diffuse emissions (radio to gamma rays). While very detailed numerical models of CR propagation exist, a quantitative statistical analysis of such models has been so far hampered by the large computational effort that those models require. We are presenting a working method for a full Bayesian parameter estimation for a numerical CR propagation model GALPROP, the most advanced of its kind to self-consistently predict CRs, gamma rays, synchrotron, and other observables. We demonstrate that a full Bayesian analysis is possible using nested sampling and Markov Chain Monte Carlo methods (implemented in the SuperBayeS code) despite the heavy computational demands. The best-fit values of parameters are in agreement with previous studies also based on GALPROP. [Preview Abstract] |
Saturday, April 30, 2011 2:30PM - 2:42PM |
C11.00006: Effects of the galactic magnetic field on observed properties of ultra-high energy cosmic rays Azadeh Keivani We present the results of propagating ultra high energy protons and iron nuclei through several models of the galactic magnetic field (GMF) using the CRT code. In this analysis, the particles have been injected from the locations of active galactic nuclei (AGN) in the VCV catalog. We analyze the correlations of the observed arrival directions with the AGN directions and study differences of the energy spectrum observed at earth from that injected at the AGN. [Preview Abstract] |
Saturday, April 30, 2011 2:42PM - 2:54PM |
C11.00007: The Ultra High Energy Cosmic Ray Spectrum as Measured in Monocular Mode John Matthews, Charles Jui, Doug Rodriguez One of the three fluorescence stations in the Telescope Array (TA) Experiment was constructed using refurbished telescopes from the High Resolution Fly's Eye (HiRes) Experiment. Specifically, the TA Middle Drum (MD) site is instrumented with detectors previously used at the HiRes-1 site. The inclusion of the MD site makes possible a direct comparison between the fluorescence energy scales and spectra between TA and HiRes. We will present the analysis and spectrum from this data. [Preview Abstract] |
Saturday, April 30, 2011 2:54PM - 3:06PM |
C11.00008: Measurement of the UHECR Flux by the Telescope Array Fluorescence Detectors Sean Stratton, Douglas Bergman The Telescope Array (TA), the first dedicated Northern Hemisphere ``hybrid'' ultrahigh energy cosmic ray (UHECR) detector, is online in Millard County, Utah. The three Fluorescence Detector sites (FD) located at Black Rock Mesa, Long Ridge, and Middle Drum have been taking data since November 2007. By measuring the characteristics of UHECR-induced extensive air showers using the FD, we can measure the energies, composition and arrival directions of the highest energy cosmic rays. We will show data from the experiment, comparisons with simulated data from our full Monte Carlo simulation program and our measurement of the UHECR energy spectrum. [Preview Abstract] |
Saturday, April 30, 2011 3:06PM - 3:18PM |
C11.00009: Energy Spectrum Measured with Telescope Array Surface Detector Dmitri Ivanov, Benjamin Stokes, Gordon Thomson The Telescope Array experiment (TA) is the largest cosmic ray experiment in the northern hemisphere. It consists of a surface detector (SD) of 507 scintillation counters and three fluorescence detector stations overlooking the SD. We are analyzing the data collected by TA SD using a new technique which consists of generating a Monte Carlo (MC) simulation with all characteristics of the real data, comparing the MC with the data to verify the validity of the MC, and calculation of the SD aperture from the MC information. We will present our analysis, based solely upon the data, our method of generating CORSIKA showers without the problems caused by thinning, comparisons of our MC with the real data, and the latest TA SD energy spectrum result. [Preview Abstract] |
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