title: Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA.
abstract: We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here, we report on characteristics of these three unusual CR events, which develop nearly horizontally, 20-30 km above the surface of Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ-lepton decay as the origin of this event, but such an interpretation would require significant suppression of the standard model τ-neutrino cross section.
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: P W
authors: PW
authors: Gorham
authors: Department of Physics, Graduate Institute of Astrophysics and Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan.
authors: J
authors: J
authors: Nam
authors: Jet Propulsion Laboratory, Pasadena, California 91109, USA.
authors: A
authors: A
authors: Romero-Wolf
authors: Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, USA.
authors: S
authors: S
authors: Hoover
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.|Center for Cosmology and Particle Astrophysics, Ohio State University, Columbus, Ohio 43210, USA.
authors: P
authors: P
authors: Allison
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
authors: O
authors: O
authors: Banerjee
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.|Center for Cosmology and Particle Astrophysics, Ohio State University, Columbus, Ohio 43210, USA.
authors: J J
authors: JJ
authors: Beatty
authors: Jet Propulsion Laboratory, Pasadena, California 91109, USA.
authors: K
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authors: Belov
authors: Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA.
authors: D Z
authors: DZ
authors: Besson
authors: Department of Physics, Washington University in St. Louis, St. Louis, Missouri 63130, USA.
authors: W R
authors: WR
authors: Binns
authors: Department of Physics, Washington University in St. Louis, St. Louis, Missouri 63130, USA.
authors: V
authors: V
authors: Bugaev
authors: Department of Physics, University of Delaware, Newark, Delaware 19716, USA.
authors: P
authors: P
authors: Cao
authors: Department of Physics, Graduate Institute of Astrophysics and Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan.
authors: C
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authors: Chen
authors: Department of Physics, Graduate Institute of Astrophysics and Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan.
authors: P
authors: P
authors: Chen
authors: Department of Physics, University of Delaware, Newark, Delaware 19716, USA.
authors: J M
authors: JM
authors: Clem
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.|Center for Cosmology and Particle Astrophysics, Ohio State University, Columbus, Ohio 43210, USA.
authors: A
authors: A
authors: Connolly
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
authors: B
authors: B
authors: Dailey
authors: Department of Physics, Enrico Fermi Institute, Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA.
authors: C
authors: C
authors: Deaconu
authors: Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
authors: L
authors: L
authors: Cremonesi
authors: Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, USA.
authors: P F
authors: PF
authors: Dowkontt
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: M A
authors: MA
authors: DuVernois
authors: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors: R C
authors: RC
authors: Field
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: B D
authors: BD
authors: Fox
authors: Department of Physics, University of California, Irvine, California 92697, USA.
authors: D
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authors: Goldstein
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
authors: J
authors: J
authors: Gordon
authors: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
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authors: Hast
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: C L
authors: CL
authors: Hebert
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: B
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authors: Hill
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
authors: K
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authors: Hughes
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
authors: R
authors: R
authors: Hupe
authors: Department of Physics, Washington University in St. Louis, St. Louis, Missouri 63130, USA.
authors: M H
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authors: Israel
authors: Department of Physics, University of Delaware, Newark, Delaware 19716, USA.
authors: A
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authors: Javaid
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: J
authors: J
authors: Kowalski
authors: Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, USA.
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authors: Lam
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
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authors: Learned
authors: Jet Propulsion Laboratory, Pasadena, California 91109, USA.
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authors: Liewer
authors: Department of Physics, Graduate Institute of Astrophysics and Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan.
authors: T C
authors: TC
authors: Liu
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: J T
authors: JT
authors: Link
authors: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors: E
authors: E
authors: Lusczek
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: S
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authors: Matsuno
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
authors: B C
authors: BC
authors: Mercurio
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: C
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authors: Miki
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
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authors: Miočinović
authors: Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
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authors: Mottram
authors: Department of Physics, University of Delaware, Newark, Delaware 19716, USA.
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authors: Jet Propulsion Laboratory, Pasadena, California 91109, USA.
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authors: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
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authors: Ng
authors: Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
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authors: Nichol
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
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authors: Palladino
authors: Department of Physics, Washington University in St. Louis, St. Louis, Missouri 63130, USA.
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authors: Rauch
authors: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
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authors: Reil
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
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authors: J
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authors: Russell
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: L
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authors: Ruckman
authors: Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, USA.
authors: D
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authors: Saltzberg
authors: Department of Physics, University of Delaware, Newark, Delaware 19716, USA.
authors: D
authors: D
authors: Seckel
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: H
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authors: Schoorlemmer
authors: Department of Physics, Ohio State University, Columbus, Ohio 43210, USA.
authors: S
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authors: Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA.
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authors: Stockham
authors: Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA.
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authors: Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom.
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authors: Strutt
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: K
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authors: Tatem
authors: Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
authors: G S
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authors: Varner
authors: Department of Physics, Enrico Fermi Institute, Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA.
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authors: Vieregg
authors: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
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authors: Physics Department, California Polytechnic State University, San Luis Obispo, California 93407, USA.
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authors: Wissel
authors: Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, USA.
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