Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA

P. W. Gorham, J. Nam, A. Romero-Wolf, S. Hoover, P. Allison, O. Banerjee, J. J. Beatty, K. Belov, D. Z. Besson, W. R. Binns, V. Bugaev, P. Cao, C. Chen, P. Chen, J. M. Clem, A. Connolly, B. Dailey, C. Deaconu, L. Cremonesi, P. F. DowkonttM. A. Duvernois, R. C. Field, B. D. Fox, D. Goldstein, J. Gordon, C. Hast, C. L. Hebert, B. Hill, K. Hughes, R. Hupe, M. H. Israel, A. Javaid, J. Kowalski, J. Lam, J. G. Learned, K. M. Liewer, T. C. Liu, J. T. Link, E. Lusczek, S. Matsuno, B. C. Mercurio, C. Miki, P. Miočinović, M. Mottram, K. Mulrey, C. J. Naudet, J. Ng, R. J. Nichol, K. Palladino, B. F. Rauch, ANITA Collaboration

Research output: Contribution to journalArticlepeer-review

117 Scopus citations


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.

Original languageEnglish (US)
Article number071101
JournalPhysical review letters
Issue number7
StatePublished - Aug 8 2016

Bibliographical note

Funding Information:
We thank NASA for their generous support of ANITA, the Columbia Scientific Balloon Facility for their excellent field support, and the National Science Foundation for their Antarctic operations support. This work was also supported by the U.S. Department of Energy, High Energy Physics Division.

Publisher Copyright:
© 2016 American Physical Society.


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