Bulletin of the American Physical Society
APS April Meeting 2014
Volume 59, Number 5
Saturday–Tuesday, April 5–8, 2014; Savannah, Georgia
Session R8: Gamma-ray and Neutrino Observations |
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Sponsoring Units: DAP Chair: Keith Bechtol, University of Chicago Room: 202 |
Monday, April 7, 2014 10:45AM - 10:57AM |
R8.00001: IceCube Results for Diffuse Muon Neutrinos Christopher Weaver Recent results from the IceCube Neutrino Observatory provide evidence for high energy astrophysical neutrinos in an analysis using events whose interactions occurred within the detector volume. In this talk I will show the results of a complimentary analysis using neutrino-induced muon events which enter the detector from outside, with a focus on the region of energies around 100 TeV where the hypothetical best-fit astrophysical flux corresponding to the contained event data begins to dominate over the conventional atmospheric muon neutrino flux. [Preview Abstract] |
Monday, April 7, 2014 10:57AM - 11:09AM |
R8.00002: Search for diffuse extraterrestrial contained neutrino-induced cascades using IceCube 79- and 86-string configurations Mariola Lesiak-Bzdak, Joanna Kiryluk IceCube, a cubic kilometer detector at the South Pole, is the largest neutrino telescope currently taking data. Utilizing the transparent ice of Antarctica as a detection medium, IceCube digital optical sensors observe Cherenkov radiation from secondary particles produced in neutrino interactions inside or near the detector. Charged current $\nu_{\mu}$ interactions create muon tracks, while charged current $\nu_{e}$ interactions, and neutral current interactions of all flavors initiate electromagnetic and hadronic showers (cascades). The goal of this study is to search for extraterrestrial neutrino-induced cascades, contained within the detector volume, with energies in the tens of TeV to a few PeV neutrino energy range and characterize the diffuse neutrino flux measured in IceCube. The analysis uses 662 days of livetime of the data taken from May 2010 to May 2012 with 79- and 86- string IceCube configurations. The analysis method and results of the likelihood fits to the cascade energy spectra from the fully unblinded datasets will be presented. [Preview Abstract] |
Monday, April 7, 2014 11:09AM - 11:21AM |
R8.00003: Searches for Point Sources of Astrophysical Neutrinos with the IceCube Neutrino Telescope Jacob Feintzeig IceCube, a cubic kilometer cherenkov detector at the South Pole, has recently found evidence for a diffuse flux of astrophysical neutrinos in the TeV - PeV energy range. These neutrinos are likely produced in high-energy cosmic ray interactions near their acceleration sites. To elucidate the sources of these cosmic rays, we search for point-like emission of astrophysical neutrinos. Results from searches using four years of throughgoing muon data, including data from the first year of the completed detector, will be shown. We will also describe point source analyses using contained-vertex events. These analyses more effectively reduce the atmospheric muon background, lowering the energy threshold in the southern hemisphere to below $\sim$ 100 TeV. [Preview Abstract] |
Monday, April 7, 2014 11:21AM - 11:33AM |
R8.00004: Measurement of the cosmic ray energy spectrum with IceCube Bakhtiyar Ruzybayev We report on the measurement of the all-particle cosmic ray energy spectrum with IceCube. The presented spectrum is in the energy range from 1.58 PeV to 2.5 EeV using the 3 years of data from the IceTop air shower array, compared to the previously reported data from a single year. IceTop is the surface component of the IceCube Neutrino Observatory at the South Pole. The measured energy spectrum exhibits clear deviations from a single power law above the knee around 4 PeV and below 1 EeV. [Preview Abstract] |
Monday, April 7, 2014 11:33AM - 11:45AM |
R8.00005: Muon-induced spallation backgrounds for MeV astrophysical neutrino signals in Super-Kamiokande Weishi Li, John Beacom When muons travel through matter, their energy losses lead to nuclear breakup (``spallation'') processes. The subsequent decays of unstable daughter nuclei produced by cosmic-ray muons are important backgrounds for low-energy astrophysical neutrino experiments. Even though Super-Kamiokande has strong cuts to reduce these spallation-induced backgrounds, the remaining rate is much larger than the signal rates for energies 8 - 18 MeV. We show how muons induce showers in water, produce secondary particles, and how these secondaries produce isotopes. We outline how to implement more effective background rejection techniques using this information. This could lead to new physics results, as both solar and Diffuse Supernova Neutrino Background studies are background-limited, and reducing backgrounds by even a factor of a few could quickly lead to new discoveries. [Preview Abstract] |
Monday, April 7, 2014 11:45AM - 11:57AM |
R8.00006: The Cherenkov Telescope Array Valerie Connaughton The Cherenkov Telescope Array (CTA) is a large collaborative effort dedicated to the design and operation of the next-generation ground-based very high-energy gamma-ray observatory. CTA will improve by about one order of magnitude the sensitivity with respect to the current major arrays (VERITAS, H.E.S.S., and MAGIC) in the core energy range of 100 GeV to 10 TeV, and will extend the viability of the imaging atmospheric Cherenkov technique (IACT) down to tens of GeV and above 100 TeV. In order to achieve such improved performance at both a northern and southern CTA site, four 23m diameter Large Size Telescopes (LST) optimized for low energy gamma rays will be deployed close to the centre of the array. A larger number of Medium Size Telescopes (MST) will be optimized for the core IACT energy range. The southern site will include 25 12m single-mirror MSTs and a US contribution of up to 24 novel dual-mirror design Schwarzschild-Couder (SC) type MSTs with a primary mirror of 9.5m diameter, and will also include an array of Small Size Telescopes (SST) to observe the highest-energy gamma rays from galactic sources. The SSTs can be smaller and more widely separated because more energetic gamma rays produce a larger Cherenkov light pool with many photons. The SSTs achieve a large collection area by covering a wide (10 sq km) footprint on the ground. The CTA project is finishing its preparatory phase, and the pre-production phase will start this year. I will review the status and the expected performance of CTA as well as the main scientific goals for the observatory. [Preview Abstract] |
Monday, April 7, 2014 11:57AM - 12:09PM |
R8.00007: HAWC Observations of Galactic TeV Gamma-Ray Sources Hao Zhou The High Altitude Water Cherenkov experiment, HAWC, is a ground based TeV gamma-ray observatory being built in Sierra Negra, Mexico at an altitude of 4100 meters above sea level. When complete it will be an array consisting of 300 water Cherenkov detectors, each equipped with four photomultiplier tubes that detect the Cherenkov light produced by the secondary particles of extensive air showers. One third of the array has been operating and collecting data since summer 2013 and the full array is expected to come online in fall 2014. I will present HAWC observations of known galactic gamma-ray objects, with a focus on pulsar wind nebulae, especially the pulsar wind nebula of the Geminga pulsar, which is the first pulsar that was discovered via gamma-ray observations. [Preview Abstract] |
Monday, April 7, 2014 12:09PM - 12:21PM |
R8.00008: Excess of Diffuse Gamma-ray Emission from the Inner Galaxy: Bubbles, Jets, Dark Mater Meng Su I will first talk about recent progress on the study of Galactic diffuse gamma-ray emission, with the focus on the discovery of Fermi gamma-ray bubbles and multi-wavelength observations on this structure. I will further show evidence for collimated jet/cocoon structure in the inner Galaxy. Our numerical simulation demonstrates that the bubble structure could be evidence for past accretion events of the central supermassive black hole. I will then summarize the current state of dark matter search with Fermi Gamma-ray Space Telescope data, with the focus on gamma-ray line searching from the Galactic center, galaxy clusters, and dwarf galaxies. I will also discuss possible instrumental systematics of the Fermi-LAT instrument that might contaminate the~line~searching with a overview of the future prospective. Finally, we have recently proposed to change the survey strategy of Fermi to increase the exposure at Galactic center by more than a factor of 2 over 2014.~This survey strategy has been initiated since December 2013. [Preview Abstract] |
Monday, April 7, 2014 12:21PM - 12:33PM |
R8.00009: The Search for Annihilating Dark Matter with The High Altitude Water Cherenkov (HAWC) Observatory J. Patrick Harding The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to 100 GeV - 100 TeV gamma rays and cosmic rays. Located at an elevation of 4100 m on the Sierra Negra mountain in Mexico, HAWC observes extensive air showers from gamma and cosmic rays with an array of water tanks which produce Cherenkov light in the presence of air showers. With a wide field-of-view observing 2/3 of the sky each day and a sensitivity of ~1 Crab/day, HAWC has the ability to probe many sources for the signals of TeV-mass dark matter. I will show some results from the portion of the HAWC detector already built, HAWC-111, as well as the predicted sensitivity to dark matter for the full detector. [Preview Abstract] |
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