Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session P7: Cosmic Rays and Solar Physics I |
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Sponsoring Units: DAP Chair: Stefan Westerhoff, Columbia University Room: Hyatt Regency Dallas Pegasus A |
Monday, April 24, 2006 10:45AM - 10:57AM |
P7.00001: Searching for high energy cosmic ray electrons using the Earth's magnetic field. S. Nutter, C. Bower, S. Coutu, M. DuVernois, A. Martell, D. Muller, J. Musser, M. Schubnell, G. Tarle, A. Yagi The Cosmic Ray Electron Synchrotron Telescope (CREST) instrument is a balloon payload designed to measure the flux of primary cosmic ray electrons at energies greater than 2 TeV. Because electrons at these energies lose energy rapidly during propagation through the interstellar medium, their detection would indicate the existence of sources which are within a few kiloparsecs. In order to obtain the needed large exposure time and aperture of the detector, we use an approach that depends on the detection of synchrotron photons emitted when the electrons travel through the earth's magnetic field. Such photons have energies in the x-ray and gamma-ray region, hence CREST incorporates an array of inorganic scintillators. Since the primary electrons do not need to pass through the detector, the effective detection area is much larger than the actual detector array size. To verify the technique and to determine background count rates, a prototype array of BGO and BaF2 crystals was flown on high altitude balloon from Ft. Sumner, N.M. in autumn 2005. The full detector system is currently under construction. It will consist of a 1600 crystal array, and will be carried on Long-Duration Balloons on circumpolar trajectory. [Preview Abstract] |
Monday, April 24, 2006 10:57AM - 11:09AM |
P7.00002: Measurement of the Relative Abundances of the Ultra-Heavy Galactic Cosmic-Rays ($30 \leq Z \leq 40$) 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 (UH) 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 four scintillation counters, two Cherenkov counters, and a scintillating fiber hodoscope. TIGER has accumulated data on two successful flights from McMurdo, Antarctica: the first launched in December of 2001 with a total flight duration of 31.8 days and the second in December of 2003 with a total flight duration of 18 days. The two flights of TIGER achieved sufficient statistics and charge resolution to resolve $\sim$140 particles with $Z>30$, and have provided the best measurements to date for $_{30}$Zn, $_{31}$Ga, $_{32}$Ge, and $_{34}$Se. We present the relative abundances of the UH-GCRs as measured by TIGER and as propagated to the top of the atmosphere. These abundances are compared with GCR source models. [Preview Abstract] |
Monday, April 24, 2006 11:09AM - 11:21AM |
P7.00003: Co/Ni Ratio in Galactic Cosmic Rays: Results from the TIGER-2001 Flight G.A. de Nolfo, L.M. Barbier, J.R. Cummings, J.W. Mitchell, R.E. Streitmatter, W.R. Binns, M.H. Israel, J.T. Link, B.F. Rauch, L.M. Scott, S. Geier, R.A. Mewaldt, S.M. Schindler, E.C. Stone, C.J. Waddington, M.E. Wiedenbeck The Trans-Iron Galactic Element Recorder (TIGER) has completed two successful Antarctic flights in December/January of 2001 and 2003. TIGER was designed to observe elements in galactic cosmic rays (GCR) ranging from 14 $\le $ Z $\le $ 40 over an extended energy range. Observations of the isotopes of Co and Ni at low energies, in particular, the observation of $^{59}$Ni and $^{59}$Co from the Cosmic Ray Isotope Spectrometer on Advanced Composition Explorer, indicate that a significant time delay ($>$7.6x10$^{4}$ yr) exists between nucleosynthesis and acceleration of GCRs. While TIGER is not able to resolve isotopes, observations of the elemental abundance of Co and Ni at energies higher than CRIS/ACE further constrain models for GCR acceleration and propagation. With a 2001 flight of nearly 32 days, TIGER collected sufficient statistics to study the Co/Ni elemental ratio over a wide range in energy from $\sim $0.8-5 GeV/nucleon. We present the Co/Ni ratio observed from TIGER's first successful Antarctic flight in 2001 and compare these results with previous observations and with the predictions from GCR propagation models. [Preview Abstract] |
Monday, April 24, 2006 11:21AM - 11:33AM |
P7.00004: The High Resolution Fly's Eye Detector and Measurement of the UHECR Spectrum William Hanlon The High Resolution Fly's Eye detector is an atmospheric fluorescence detector that has been searching for ultra high energy cosmic rays since 1997. It was designed to observe cosmic rays with energies above $3 \times 10^{18}$ eV in stereo. A brief description of the detector and techniques used to observe these elusive particles will be presented. Recent stereoscopic spectrum results will also discussed. [Preview Abstract] |
Monday, April 24, 2006 11:33AM - 11:45AM |
P7.00005: Search for Cross-Correlations of Ultra--High-Energy Cosmic Rays Chad Finley, Stefan Westerhoff The High Resolution Fly's Eye (HiRes) experiment is a stereo air fluorescence detector for the study of cosmic rays with energies above $5\times 10^{17}$\,eV. Arrival directions of cosmic rays observed in stereo can be resolved with a typical uncertainty on the order of $0.5^{\circ}$, making the experiment ideal for small-scale anisotropy studies. We will review recent claims of evidence for correlations between ultrahigh-energy cosmic rays and active galaxies of the BL Lac subclass, and we will describe tests of these claims with new data. [Preview Abstract] |
Monday, April 24, 2006 11:45AM - 11:57AM |
P7.00006: 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$^{o}$. 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] |
Monday, April 24, 2006 11:57AM - 12:09PM |
P7.00007: On Measuring the Ultra High Energy Cosmic Ray Spectrum above 3 $\times $ 10$^{18}$ eV by Pierre Auger Observatory Joong Lee We report the Ultra High Energy Cosmic Ray (UHECR) spectrum above 3 $\times $ 10$^{18}$ eV measured by Pierre Auger Observatory (PAO). PAO uses both the Fluorescence detector (FD) and the water cerenkov tank surface detectors (SD). PAO offers an exciting opportunity to compare the systematics of and cross-calibrate FD and SD for the first time. [Preview Abstract] |
Monday, April 24, 2006 12:09PM - 12:21PM |
P7.00008: Observation of the GZK Cutoff Douglas Bergman The GZK Cutoff is the predicted end of the cosmic ray spectrum at an energy of about $6\times10^{19}$ eV, and is due to interactions between the cosmic rays and the microwave background. The cutoff was predicted soon after the discovery of the Cosmic Microwave Background, and his been called the Holy Grail of Ultrahigh Energy Cosmic Ray physics. We use evidence from fits to the published HiRes Monocular differential spectra and from the $E_{1/2}$ criterion, the energy at which the measured integral spectrum is half the expected integral spectrum with no cutoff, to argue that HiRes has observed this cutoff. [Preview Abstract] |
Monday, April 24, 2006 12:21PM - 12:33PM |
P7.00009: MARIACHI - Detecting Ultra High Energy Cosmic Rays with radar. Helio Takai Ultra High Energy Cosmic Rays with energies in excess of 10$^{20}$eV (100 EeV) have been detected by several experiments. They present a conundrum whose solution may provide insight into the origins and evolution of the universe. There are no known sources within our galaxy or those close to us that could accelerate particles to these almost macroscopic energies, and yet the turn-on of pion production through the interactions of high energy charged particles with the 2.7K microwave background provides a strong limit for propagation from greater distances. The detection of UHECR to date has been accomplished either by detection of the particles from the extensive air showers by ground arrays or by means of detection of the light produced by the EAS in the atmosphere from Cerenkov radiation. MARIACHI (Mixed Apparatus for Radar Investigation of Cosmic-rays of High Ionization) is an innovative concept that will explore the detection of UHECR by bi-static radar using VHF transmitters. If successful, the MARIACHI technique will allow for detection of UHECR economically over much larger areas than currently possible, and might provide for detection of the associated ultra high energy neutrino flux. MARIACHI is also innovative in that ground array detectors that will initially confirm the radio signals are scintillator arrays to be built and operated by high school students and teachers. We will present the present status of the experiment. [Preview Abstract] |
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