Bulletin of the American Physical Society
APS April Meeting 2014
Volume 59, Number 5
Saturday–Tuesday, April 5–8, 2014; Savannah, Georgia
Session J8: Ultra-high Energy Cosmic Rays |
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Sponsoring Units: DAP Chair: Lawrence Wiencke, Colorado School of Mines Room: 202 |
Sunday, April 6, 2014 10:45AM - 10:57AM |
J8.00001: High Energy Neutrino Emission Induced by Ultrahigh Energy Nuclei in Cluster Accretion Shocks Ke Fang, Angela Olinto Accretion shocks in clusters of galaxies can potentially accelerate protons to above $10^{17}\,\rm eV$ and nuclei to ultrahigh energies. High energy neutrinos are produced when these cosmic rays interact with baryons of the massive cluster, or with CMB photons during their extragalactic propagation. In light of the recent IceCube discovery of TeV-PeV neutrinos, we calculate the neutrino emissions from accretion shocks, using a complete numerical propagation method and calibrated based on precision $\Lambda$CDM simulation. We pin down the uncertainty and degeneracy in source parameters by taking into account the cosmological evolution of cluster mass, density profiles, velocity dispersions, along with the gravitational gas accretion rates. We find that the neutrino spectrum is distinct from $E^{-2}$ after considering the cluster mass function which impact both maximum energy and luminosity of the accelerated cosmic rays. We compare the cumulative neutrino flux to sensitivities of the existing and future high energy neutrino observatories. We also discuss the implication of our results on the scenario of cluster accretion shocks being the sources of ultrahigh energy cosmic rays. [Preview Abstract] |
Sunday, April 6, 2014 10:57AM - 11:09AM |
J8.00002: Multiwavelength calibration of the Pierre Auger Observatory fluorescence detectors and its effect on reconstructed parameters Ben Gookin, Jeff Brack, Alexei Dorofeev, John Harton, Yevgeniy Petrov The fluorescence detector of the Pierre Auger Observatory is sensitive to primary particle composition of cosmic rays through the measurement of the depth of shower maximum, X$_{max}$. X$_{max}$ as a function of energy, or the elongation rate, depends on the primary particle composition, and any uncertainty in the X$_{max}$ measurement could lead to a bias in the interpretation of the elongation rate. One uncertainty may arise from how the detector efficiency is calibrated as a function of wavelength. The calibration of the Pierre Auger Observatory fluorescence detector is performed using a uniform 2.5m diameter light source that allows for an end-to-end measurement of all detector components. The multiwavelength calibration utilizes the 2.5m diameter light source where the output of a xenon flasher is fed into a monochromator and the monochromator selects single wavelengths across the nitrogen fluorescence spectrum to measure the efficiency of the detector. A recent change in fluorescence detector efficiency altered the energy scale of the Pierre Auger Observatory by 4\%. Presented here is the effect on X$_{max}$ due to the above change in efficiency and preliminary results from a more detailed multiwavelength calibration and its effects on energy reconstruction and X$_{max}$. [Preview Abstract] |
Sunday, April 6, 2014 11:09AM - 11:21AM |
J8.00003: Study of double-bump air showers contaminated by clouds and Cherenkov light Amir Shadkam Complex air shower development (``double-bumps") can be used to study hadronic physics at high energy but can also arise from other effects. Fits using two Gaussian functions of the age-parameter have been applied to the Pierre Auger Observatory data and have identified a large set of events with irregular shower profile shapes. Clouds can scatter the air shower fluorescence and Cherenkov light and affect the amount of detected light. Cloud maps extracted from GOES satellites data are used to identify the events contaminated with clouds. Also some examples of contamination with direct Cherenkov light are presented here. [Preview Abstract] |
Sunday, April 6, 2014 11:21AM - 11:33AM |
J8.00004: Fluoresence Detection of Cosmic Ray Air Showers Between $10^{16.5}$ eV and $10^{19}$ eV with the Telescope Array Low Energy Extension (TALE) Zachary Zundel, Jeremy Smith, Stan Thomas, Tareq AbuZayyad, Dmitri Ivanov, John Matthews, Charlie Jui The Telescope Array Experiment has been observing cosmic ray air showers at energies above $10^{18}$ eV since 2008. TA operates three Fluorescence Detector (FD) sites, with telescopes that observe 3-31 deg in elevation. The FD sites are located at the periphery of a surface array of 507 scintillation counters covering 700 $km^{2}$, with 1.2km spacing. The TA Collaboration has completed building a low-energy extension at its Middle drum FD site. Ten new telescopes currently observe between 33 and 51 degrees in elevation. A graded ground array of between 400 and 600m will be placed in front of the TALE FD. With these upgrades, the physics threshold of TA will be lowered to $10^{16.5}$ eV. The TA Low Energy Extension(TALE) will explore the energy regime corresponding to that of the LHC in center-of-mass frame. This is also the range where the transition from galactic to extra- galactic cosmic ray flux is suspected to occur. We will give a brief overview of the physics, and report on the progress of TALE toward measuring the cosmic ray spectrum between $10^{16.5}$ eV and $10^{19}$ eV. [Preview Abstract] |
Sunday, April 6, 2014 11:33AM - 11:45AM |
J8.00005: Telescope Array measurement of UHECR composition from stereoscopic fluorescence detection Thomas Stroman, Douglas Bergman, Tareq Abu Zayyad The chemical composition of ultra-high-energy cosmic rays (UHECRs) is an important constraint on models of UHECR production and propagation, and must be determined experimentally. A UHECR-induced extensive air shower's longitudinal development is dictated by the energy per nucleon of the primary particle. The observed distribution of atmospheric slant depths ($X_{\rm max}$) is therefore sensitive to the composition, facilitating measurement of the relative abundances of ``light'' (proton-like) and ``heavy'' (iron-like) primary UHECR particles. The Telescope Array (TA) experiment, the northern hemisphere's largest UHECR detector, includes three fluorescence detector (FD) stations that record the longitudinal development of the extensive air showers produced by UHECR arrivals. ``Stereo'' observation of individual showers by multiple FDs tightly constrains the trajectory reconstruction, allowing a precise measurement of $X_{\rm max}$ as well as energy. We will present the stereo TA data from six years of operation and progress toward a measurement of chemical composition. [Preview Abstract] |
Sunday, April 6, 2014 11:45AM - 11:57AM |
J8.00006: Anisotropy in Cosmic Ray Arrival Directions Observed by the Telescope Array Benjamin Stokes The Telescope Array cosmic ray observatory has now accumulated more than five years of data. For ultra-high energy cosmic rays, this has resulted in an event set several times larger than what was previously available for the Northern Hemisphere. Ongoing arrival direction anisotropy searches include correlation to astrophysical catalogs, harmonic analysis, and point sources. Current results will be presented. [Preview Abstract] |
Sunday, April 6, 2014 11:57AM - 12:09PM |
J8.00007: First Results from the Telescope Array RAdar (TARA) Detector Isaac Myers The TARA cosmic ray detector has been in operation for about a year and a half. This bi-static radar detector was designed with the goal of detecting cosmic rays in coincidence with Telescope Array (TA). A new high power (25 kW, 5 MW effective radiated power) transmitter and antenna array and 250 MHz fPGA-based DAQ have been operational since August 2013. The eight-Yagi antenna array broadcasts a 54.1 MHz tone across the TA surface detector array toward our receiver station 50 km away at the Long Ridge fluorescence detector. Receiving antennas feed an intelligent DAQ that self-adjusts to the fluctuating radio background and which employs a bank of matched filters that search in real-time for chirp radar echoes. Millions of triggers have been collected in this mode. A second mode is a forced trigger scheme that uses the trigger status of the fluorescence telescope. Of those triggers collected in FD-triggered mode, about 800 correspond with well-reconstructed TA events. I will describe recent advancements in calibrating key components in the transmitter and receiver RF chains and the analysis of FD-triggered data. [Preview Abstract] |
Sunday, April 6, 2014 12:09PM - 12:21PM |
J8.00008: ABSTRACT WITHDRAWN |
Sunday, April 6, 2014 12:21PM - 12:33PM |
J8.00009: The Global Light System for JEM-EUSO Lawrence Wiencke, Jim Adams, Mark Christl, Johannes Eser, Fred Sarazin The sources of the highest energy particles known to exist in the universe remain an open question. The falling energy spectrum and low flux of these extreme energy messengers pose a measurement challenge for current and next generation detectors. Particle test beams at 100 EeV do not exist. Calibrated light sources (UV pulsed lasers and Xe Flashers) directed into the sky provide a proven alternative. The optical signatures that these sources generate in air fluorescence detectors have similarities to the optical signatures of the very rare 100 EeV air showers. The Global Light System (GLS) is a network of 12 calibrated Xe flashers and 6 UV lasers that will be deployed around the globe to benchmark the JEM-EUSO space based instrument. An additional GLS unit will be flown occasionally by aircraft. Prototype GLS systems in preparation will be flown by helicopter under the EUSO-Balloon instrument scheduled for flight later this year and also used to test the EUSO-TA prototype. As part of the development of the GLS, we are also planning to support the TUS orbital ultra high energy cosmic ray detector that has been prepared for launch on board the Lomonosov satellite. [Preview Abstract] |
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