Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session B11: Cosmic Rays |
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Sponsoring Units: DAP Chair: Phil Kaaret, University of Iowa Room: Hyatt Regency Jacksonville Riverfront City Terrace 7 |
Saturday, April 14, 2007 10:45AM - 10:57AM |
B11.00001: Observation of the GZK Cutoff by the HiRes Experiment John Belz We report on a decade of observation of the Ultra-high Energy Cosmic Ray spectrum by the HiRes experiment. We report on the observation of the GZK cutoff near the expected energy of 60 EeV. Associated dip structure in the spectrum near an energy of 5 EeV will also be discussed, and is consistent with electron-positron pair production energy loss mechanism for proton. [Preview Abstract] |
Saturday, April 14, 2007 10:57AM - 11:09AM |
B11.00002: Acceleration of highest energy cosmic rays Maxim Lyutikov, Rachid Ouyed Relativistic outflows carrying large scale magnetic fields have large inductive potential and may accelerate protons to ultra high energies. We discuss a novel scheme of UHECR acceleration due to drifts in cylindrically collimated, sheared extragalactic jets. A particle advected by such a jet is in an unstable equilibrium if ${\bf B} \cdot \nabla \times {\bf v}< 0$, so that kinetic drift along velocity shear leads to fast, regular energy gain. Acceleration rate does reach absolute theoretical maximum of inverse gyro-frequency. In addition, highest rigidity particles are accelerated most efficiently, implying the dominance of light nuclei at highest energies. [Preview Abstract] |
Saturday, April 14, 2007 11:09AM - 11:21AM |
B11.00003: Can $^{59}$Ni Synthesized in OB Associations Decay to $^{59}$CO Before Being Accelerated to Cosmic-Ray Energies? R. Binns, M. Israel, A. Cummings, R. Leske, R. Mewaldt, E. Stone, G. De Nolfo, T. von Rosenvinge, M. Wiedenbeck Observations from the Cosmic Ray Isotope Spectrometer (CRIS) aboard NASA's Advanced Composition Explorer (ACE) have shown that all relevant galactic cosmic ray isotopic ratios measured are consistent with an OB-Association origin of galactic cosmic rays (GCRs). Additionally CRIS measurements of the isotopic abundances of $^{59}$Ni and $^{59}$Co have shown that the $^{59}$Ni has completely decayed into $^{59}$Co, indicating a delay of $>$10$^{5}$ years between nucleosynthesis and acceleration. However, it has been suggested that shocks generated from high-velocity Wolf-Rayet winds in the OB-Association environment must accelerate nuclei synthesized in nearby core-collapse SNe on a time scale short compared to the $^{59}$Ni lifetime of 7.6x10$^{4}$ years. This would imply that OB Associations could not be the source of most galactic cosmic rays. In this paper, we describe the OB-Association history and environment and show that the time scales for acceleration are such that $^{59}$Ni should be expected to decay naturally in that setting, strengthening the argument that OB associations are the likely source of a large fraction of galactic cosmic rays. [Preview Abstract] |
Saturday, April 14, 2007 11:21AM - 11:33AM |
B11.00004: Measurement of the Atmospheric Muon Charge Ratio at TeV Energies with MINOS Gavril Giurgiu A measurement of the atmospheric muon charge ratio with the MINOS far detector is presented. The 5.4 kilo-ton MINOS far detector is located at a depth of ~710 meters underground in the Soudan mine in Minnesota. It was designed to study neutrino oscillations with the Fermilab NuMI beam in conjunction with a near detector 1 km downstream of the NuMI target. The far detector has been taking charge-separated cosmic ray data since August 2003. We measure the atmospheric muon charge ratio for underground muon energies up to 250 GeV which corresponds to a surface energy range between 1 and 7 TeV. [Preview Abstract] |
Saturday, April 14, 2007 11:33AM - 11:45AM |
B11.00005: CREAM Experiment Charge and Energy Performance Taylor Childers The Cosmic Ray Energetics And Mass (CREAM) experiment was designed to measure the elemental cosmic-ray energy spectrum (p to Fe) up to 1000 TeV. CREAM flew twice from McMurdo, Antarctica in 2004/2005 and 2005/2006. The first CREAM flight utilized many detectors, including a Calorimeter, Transition Radiation Detector, Silicon Charge Detector, Cherenkov Detector, and Timing Charge Detector. This talk will cover the CREAM instrument performance in terms of charge identification and energy measurements. [Preview Abstract] |
Saturday, April 14, 2007 11:45AM - 11:57AM |
B11.00006: High Energy Cosmic Ray Measurements with CREAM Simon Swordy The Cosmic Ray Energetics and Mass (CREAM) balloon program is a series of instruments for long duration high altitude balloon flights directed at measurements of high energy cosmic ray nuclei. The first instrument, CREAM-I, combined a transition radiation detector with a calorimeter and flew for a record 42 days around Antarctica in 2004/2005. CREAM-II carried a calorimeter and cherenkov counter and flew for 28 days in 2005/2006. This paper will discuss the scientific and technical aspects of these flights and present some early results. The plans for future CREAM flights will also be discussed. [Preview Abstract] |
Saturday, April 14, 2007 11:57AM - 12:09PM |
B11.00007: The CREAM Experiment: Towards Primary-to-Secondary Ratios Theresa Brandt The Cosmic Ray Energitics And Mass (CREAM) experiment flew around Antarctica on two balloon flights, for a total of 70 days. This multi-technique experiment, which included a Timing Charge Detector (TCD), a Transition Radiation Detector (TRD), a Silicon Charge Detector (SCD), and a Calorimeter, measured charges from Protons through Iron in the energy range 10$^{12}$ -- 10$^{15}$ eV. The combination of large aperture TCD and TRD is well-suited for measuring primary-to-secondary ratios such as Boron to Carbon. Flight performance and preliminary results from the TCD/TRD combination will be presented. [Preview Abstract] |
Saturday, April 14, 2007 12:09PM - 12:21PM |
B11.00008: Measurement of the Relative Abundances of the Ultra-Heavy Galactic Cosmic Rays ($30 \le Z \le 40$) at the Top of the Atmosphere with TIGER B.F. Rauch, W.R. Binns, M.H. Israel, J.T. Link, L.M. Scott, L.M. Barbier, J.R. Cummings, G.A. de Nolfo, J.W. Mitchell, R.E. Streitmatter, S. Geier, R.A. Mewaldt, S.M. Schindler, E.C. Stone, C.J. Waddington Observations of Ultra-Heavy galactic cosmic rays (GCR) help to distinguish the possible origins of GCRs. The Trans-Iron Galactic Element Recorder (TIGER) is designed to measure the charge ($Z$) and energy of GCRs using a combination of scintillation counters, Cherenkov counters, and a scintillating fiber hodoscope. TIGER has accumulated data on two successful flights from McMurdo, Antarctica in December of 2001 and in December of 2003 with a total flight duration of $\sim$50 days. The combined TIGER dataset achieved sufficient statistics and charge resolution to resolve $\sim$140 particle with $Z>30$, and provides the measurements to date for $_{30}$Zn, $_{31}$Ga, $_{32}$Ge, and $_{34}$Se. We present the preliminary abundances of the Ultra-Heavy GCRs derived from the combined dataset propagated to the top of the atmosphere, and discuss the results in the context of previous measurements and different GCR source models. [Preview Abstract] |
Saturday, April 14, 2007 12:21PM - 12:33PM |
B11.00009: New methods to search for Cross-Correlations between UHECR data and BL Lac sources. Rasha Abbasi The arrival direction study of Ultra High Energy Cosmic Rays gives us potentially an insight on their origin. The High Resolution Fly's Eye (HiRes) is a stereo air fluorescence experiment that detects cosmic rays with energies greater than $\sim $10$^{18}$ eV. The angular resolution of HiRes is approximately 0.6$^{\circ}$. This small uncertainty is well suited for small-scale anisotropy studies. Here we present the correlation of the observed cosmic rays by HiRes with some astronomical sources, in particular with BL Lac sources, which are a subclass of active galaxies. [Preview Abstract] |
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