%X We report the observation of 16 cosmic ray events with a mean energy of 1: 5 x 10(19) eV via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present measurements in the 300-900 MHz range, which are the first self-triggered, first ultrawide band, first far-field, and the highest energy sample of cosmic ray events collected with the radio technique. Their properties are inconsistent with current ground-based geosynchrotron models. The emission is 100% polarized in the plane perpendicular to the projected geomagnetic field. Fourteen events are seen to have a phase inversion due to reflection of the radio beam off the ice surface, and two additional events are seen directly from above the horizon. Based on a likelihood analysis, we estimate angular pointing precision of order 2 degrees for the event arrival directions.
%O © 2010 The American Physical Society
%K EXTENSIVE AIR SHOWERS, PULSES, EMISSION, SPECTRUM
%N 15
%J PHYS REV LETT
%I AMER PHYSICAL SOC
%L discovery408812
%D 2010
%T Observation of Ultrahigh-Energy Cosmic Rays with the ANITA Balloon-Borne Radio Interferometer
%A S Hoover
%A J Nam
%A PW Gorham
%A E Grashorn
%A P Allison
%A SW Barwick
%A JJ Beatty
%A K Belov
%A DZ Besson
%A WR Binns
%A C Chen
%A P Chen
%A JM Clem
%A A Connolly
%A PF Dowkontt
%A MA DuVernois
%A RC Field
%A D Goldstein
%A AG Vieregg
%A C Hast
%A MH Israel
%A A Javaid
%A J Kowalski
%A JG Learned
%A KM Liewer
%A JT Link
%A E Lusczek
%A S Matsuno
%A BC Mercurio
%A C Miki
%A P Miocinovic
%A CJ Naudet
%A J Ng
%A RJ Nichol
%A K Palladino
%A K Reil
%A A Romero-Wolf
%A M Rosen
%A L Ruckman
%A D Saltzberg
%A D Seckel
%A GS Varner
%A D Walz
%A F Wu
%V 105