BEXCO - Room D(109/110)
[NU142] Upward-Pointing Cosmic-Ray-like Events Observed with ANITA
- Andrew ROMERO-WOLF
- Andrew ROMERO-WOLF (Jet Propulsion Laboratory, California Institute of Technology)
ANITA is a NASA balloon-borne radio (200-1200 MHz) interferometer for detecting radio transients from ultra-high energy particle showers. The first flight of ANITA detected impulses due to extensive air showers identified by the correlation of the radio polarization vector with the geomagnetic field. Thirteen air shower events were detected as reflections off the ice, classified as downward-pointing events. In addition, four events have been identified as upward-pointing events. Three of them are above the geometric horizon but below the horizontal while one of them originates from the ground. The first set is consistent with stratospheric air showers, which have not been previously observed, while the latter remains a mystery. We present the characteristics of these upward-pointing events and the possible interpretation of the mystery event as a tau-lepton from a tau-neutrino interaction in the Earth.