Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session T8: Ultra-High Energy Cosmic Rays II |
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Sponsoring Units: DAP Chair: Frederic Sarazin, Colorado School of Mines Room: Governor's Square 10 |
Monday, April 15, 2013 3:30PM - 3:42PM |
T8.00001: Sensitivity of JEM-EUSO to Ensemble Fluctuations in the Ultra-High Energy Cosmic Ray Flux Thomas Paul, Markus Ahlers, Luis Anchordoqui, Andrew Taylor The energy spectrum of ultra-high energy cosmic rays (UHECR) exhibits a number of features which presumably reflect the mechanisms of cosmic acceleration, the distribution of acceleration sites, the elemental composition of the cosmic rays, and propagation effects. A coherent explanation of all UHECR measurements taken over some 50 years has so far proved to be elusive. For example, there is more than one hypothesis for the mechanism(s) responsible for the changes in spectral index observed above $10^{17}$ eV, including the very significant flux suppression at an energy near $4 \times 10^{19}$ eV. Future large exposure observatories such as the Extreme Universe Space Observatory on the Japanese Experiment Module (JEM-EUSO) will allow high statistics observation of the region around this flux suppression. One feature which may become evident in this region is the so-called ensemble fluctuation, which constitutes fluctuation in the energy spectrum beyond expectations from Poisson statistics. This as-yet unobserved feature results from the discreetness of UHECR source distribution together with propagation effects and elemental composition, and may help to enhance our understanding of the complex of UHECR features. Here we evaluate the sensitivity of JEM-EUSO to this feature. [Preview Abstract] |
Monday, April 15, 2013 3:42PM - 3:54PM |
T8.00002: Positioning of ground-based Global Light System stations around the World for the JEM-EUSO mission Zachary Norman The astrophysical origins of the Extreme Energy Cosmic Rays (EECRs - E $>10^{20}$ eV) remain a matter of debate. Data obtained on EECRs is sparse, due to the very low flux reaching the Earth. The Extreme Universe Space Observatory on board the Japanese Experiment Module (JEM-EUSO) on the International Space Station (ISS) will measure the properties of EECRs by recording the UV light produced by the air showers in Earth's atmosphere from space. At these extremely high energies, there is no way to calibrate the detector and test its operation with man-made accelerators. However, it is possible to induce the detector to see a similar amount of light by using an array of Global Light System (GLS) stations, which will use xenon flashers and lasers. The GLS locations need to be representative of the different climates around the World, because the development of the air showers depends upon the general properties of the atmosphere where it occurs. In this context, a program was developed to predict when a given GLS station is able to fire test shots within the field of view of the JEM-EUSO detector as the ISS flies over. This program takes into account the trajectory of the ISS, the relative positions of the Sun and the Moon, as well as the average cloud cover over the candidate sites. [Preview Abstract] |
Monday, April 15, 2013 3:54PM - 4:06PM |
T8.00003: Sensitivity of the orbiting JEM-EUSO mission to large-scale anisotropies Thomas Weiler, Luis Anchordoqui, Peter Denton Uniform sky coverage and very large apertures are advantages of future extreme-energy, space-based cosmic-ray observatories. In this talk we will quantify the advantage of an all-sky/4pi observatory such as JEM-EUSO over the one to two steradian coverage of a ground-based observatory such as Auger. We exploit the availability of spherical harmonics in the case of 4pi coverage. The resulting Y(lm) coefficients will likely become a standard analysis tool for near-future, space-based, cosmic-ray astronomy. We demonstrate the use of Y(lm)'s with extractions of simulated dipole and quadrupole anisotropies. (A dipole anisotropy is expected if a single source-region such as Cen A dominates the sky, while a quadrupole moment is expected if a 2D source region such as the Supergalactic Plane dominates the sky.) [Preview Abstract] |
Monday, April 15, 2013 4:06PM - 4:18PM |
T8.00004: Estimation of systematic errors in UHE CR energy reconstruction for ANITA-3 experiment Viatcheslav Bugaev, Brian Rauch, Robert Binns, Martin Israel, Konstantin Belov, Stephanie Wissel, Andres Romero-Wolf The third mission of the balloon-borne ANtarctic Impulsive Transient Antenna (ANITA-3) scheduled for December 2013 will be optimized for the measurement of impulsive radio signals from Ultra-High Energy Cosmic Rays (UHE CR), i.e. charged particles with energies above $10^{19}$ eV, in addition to the neutrinos ANITA was originally designed for. The event reconstruction algorithm for UHE CR relies on the detection of radio emissions in the frequency range 200-1200 MHz (RF) produced by the charged component of Extensive Air Showers initiated by these particles. The UHE CR energy reconstruction method for ANITA is subject to systematic uncertainties introduced by models used in Monte Carlo simulations of RF. The presented study is aimed at evaluating these systematic uncertainties by comparing outputs of two RF simulation codes, CoREAS and ZHAireS, for different event statistics and propagating the differences in the outputs through the energy reconstruction method. [Preview Abstract] |
Monday, April 15, 2013 4:18PM - 4:30PM |
T8.00005: Searching for Cosmic Ray Radar Echos In TARA Data Isaac Myers The TARA (Telescope Array Radar) cosmic ray detector has been in operation for about a year and half. This bi-static CW radar detector was designed with the goal of detecting cosmic rays in coincidence with Telescope Array (TA). For the majority of its operation it has been in the TARA1.5 phase in which a 1.5 kW transmitter broadcasts from a single Yagi antenna across the TA surface detector array to our receiver station 50 km away. Our initial DAQ system has obtained millions of triggers utilizing a USRP2 PC controlled radio. During recent months, we have commissioned a 250 MHz sample rate detector with an intelligent self-triggering algorithm that can detect radar echo chirp signals below the noise. I will describe the stages of analysis used for comparing TARA radar triggers with TA data and present a synopsis of the analysis of the USRP2 data and preliminary results from the more advanced DAQ system. [Preview Abstract] |
Monday, April 15, 2013 4:30PM - 4:42PM |
T8.00006: Noise calibration and the development of remote receiver stations for TARA Samridha Kunwar The Telescope Array RAdar (TARA) detector is based on a remote sensing technique known as bi-static radar that aims to achieve remote coverage over large portions of the Earth's surface in search of cosmic ray induced radio echoes. In conjunction with North America's largest cosmic ray observatory (The Telescope Array) in radio quiet western Utah, the radar project's pilot receiver and transmitter stations have been functional for just over a year and a half, giving insight into the detect-ability of air shower radar echoes. Currently the receiver stations comprise an array of Log Periodic Dipole Antennas with an oscilloscope-based data acquisition system implemented for noise calibration including tracking galactic noise as the galactic plane migrates through the sky. Our experiences thus far have given impetus for upgrades, including the deployment of additional remote receiver stations. We discuss some of the results of this oscilloscope-based DAQ system and the development of these remote stations. [Preview Abstract] |
Monday, April 15, 2013 4:42PM - 4:54PM |
T8.00007: Bistatic radar detection of UHECRs at Telescope Array William Hanlon The Telescope Array radar (TARA) project will utilize a bistatic radar technique to detect radar echos from the ionization trails of ultra-high energy cosmic rays as they pass through the Earth's atmosphere. It is colocated with the Telescope Array, the largest cosmic ray observatory in the northern hemisphere, which will provide additional confirmation of the detection and properties of UHECRs via time coincidence. This method of observing cosmic rays has been unproven and is the largest and most ambitious attempt yet at UHECR detection utilizing an array of high gain yagi antennas broadcasting 8 MW of effective radiated power over the TA surface detector array. Recently TARA has been field testing a low power version of the experiment to gain expertise and study techniques to better utilize the radar method on a much larger scale. Soon TARA will begin high power operations and will be the first experiment to utilize this technique at such high power in conjunction with such a large cosmic ray detector. I will discuss the physics of UHECR detection via bistatic radar and the design and goals of the TARA project. I will also discuss recent tests of radar echo detection utilizing TA's electron light source which provides {\it in situ} small air showers used for TA calibration. [Preview Abstract] |
Monday, April 15, 2013 4:54PM - 5:06PM |
T8.00008: The Non-Imaging CHErenkov Array (NICHE): A TA/TALE extension to measure the flux and composition of Very-High Energy Cosmic Rays Douglas Bergman, John Krizmanic, Pierre Sokolsky Co-sited with TA/TALE, the Non-Imaging CHErenkov Array (NICHE) will measure the flux and nuclear composition of cosmic rays from below $10^{16}$ eV to over $10^{18}$ eV in its initial deployment. Furthermore, the low-energy reach can be lowered below the cosmic ray knee via counter redeployment or additional counters. NICHE uses easily deployable detectors to measure the amplitude and time-spread of the air-shower Cherenkov signal to achieve an event-by-event measurement of $X_{\rm max}$ and energy, each with excellent resolution. NICHE will have sufficient area and angular acceptance to have significant overlap with the TA/TALE detectors to allow for energy cross-calibration. Simulated NICHE performance has shown that the array has the ability to distinguish between several different composition models as well as measure the end of Galactic cosmic ray spectrum. In this talk, the NICHE design, array performance, and status will be discussed as well as NICHE's ability to measure the cosmic ray nuclear composition as a function of energy. [Preview Abstract] |
Monday, April 15, 2013 5:06PM - 5:18PM |
T8.00009: Simulating hadronic interactions with SIBYLL Felix Riehn, Ralph Engel, Thomas K. Gaisser, Todor Stanev Sibyll 2.1 is an event generator for hadron interactions at the highest energies that is commonly used to analyze and interpret data on extensive air showers. In order to have a reliable extrapolation of the hadronic interaction to a few hundred TeV it is necessary to accurately and consistently describe as much of the experimental data obtained at laboratory energy as possible. With the onset of experiments at the LHC the set of experimental data has increased significantly, thereby requiring an update of the event generators. The influence the newly measured total cross section, the particle production yields and the kinematic distributions have on the event generator will be presented as well as the effect these observables have on the simulation of extensive air showers. In particular the role of baryons and vector mesons in the development of extensive air showers are discussed. [Preview Abstract] |
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