Article

Observation of Ultra-high-energy Cosmic Rays with the ANITA Balloon-borne Radio Interferometer

Physical Review Letters (Impact Factor: 7.73). 04/2010; 105(15). DOI: 10.1103/PhysRevLett.105.151101
Source: arXiv

ABSTRACT We report the observation of sixteen cosmic ray events of 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 the first ultra-wideband, far-field
measurements of the radio spectral density of geosynchrotron emission in the
range from 300-1000 MHz. The emission is 100% linearly polarized in the plane
perpendicular to the projected geomagnetic field. Fourteen of our observed
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.

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