The first flight of the Antarctic Impulsive Transient Antenna (ANITA) experiment recorded 16 radio signals that were emitted by cosmic-ray induced air showers. The dominant contribution to the radiation comes from the deflection of positrons and electrons in the geomagnetic field, which is beamed in the direction of motion of the air shower. For 14 of these events, this radiation is reflected from the ice and subsequently detected by the ANITA experiment at a flight altitude of ∼36 km. In this paper, we estimate the energy of the 14 individual events and find that the mean energy of the cosmic-ray sample is 2.9 × 1018 eV, which is significantly lower than the previous estimate. By simulating the ANITA flight, we calculate its exposure for ultra-high energy cosmic rays. We estimate for the first time the cosmic-ray flux derived only from radio observations and find agreement with measurements performed at other observatories. In addition, we find that the ANITA data set is consistent with Monte Carlo simulations for the total number of observed events and with the properties of those events.
|Original language||English (US)|
|Number of pages||12|
|State||Published - Apr 1 2016|
Bibliographical noteFunding Information:
We would like to thank Marianne Ludwig from Karlsruhe Institute of Technology for helpful discussions and in the early days of this work. We are grateful to NASA , the U.S. National Science Foundation , the U.S. Department of Energy , and the Columbia Scientific Balloon Facility for their generous support of these efforts. We would like to extend our thanks to the 2006–2007 on-ice LDB and McMurdo crews for their support. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. J.A.-M., W.R.C., D.G.-F., and E.Z. thank Ministerio de Economía (FPA2012-39489), Consolider-Ingenio 2010 CPAN Programme (CSD2007-00042), Xunta de Galicia (GRC2013-024), Feder Fundsand Marie Curie-IRSES/EPLANET (European Particle physics Latin American NETwork), and 7th Framework Program (PIRSES- 2009-GA-246806).
- Air shower
- Cosmic rays
- Radio detection