The Antarctic Impulsive Transient Antenna (ANITA) experiment has been designed to study ultra-high-energy (UHE) cosmic neutrinos by detecting the radio pulses emitted by their interactions with the Antarctic ice sheet. This is to be accomplished using an array of radio antennas suspended from a helium balloon flying at a height of about 37,000 meters.
The neutrinos, with energies on the order of 1018 eV, produce radio pulses in the ice because of the Askaryan effect. It is believed that these high-energy cosmic neutrinos result from interaction of ultra-high-energy (1020 eV) cosmic rays with the photons of the cosmic microwave background radiation. It is thus hoped that the ANITA experiment can shed light on the origin of these cosmic rays.
ANITA-I launched from McMurdo, Antarctica in the summer of 2006-07. The array should travel around the continent with the circumpolar winds for approximately a month before being recovered by the CSBF. Each successive mission (if funded) would be at two year intervals. ANITA-II, a modified instrument with 40 antennas, launched from McMurdo Station in the summer of 2008-2009. ANITA-III, expected to improve sensitivity by a factor of 5-10, launched in December 2014. ANITA-IV launched in December 2016, with a lighter overall build, tunable notch filters and an improved trigger system.
ANITA is currently being funded by NASA.
The current ANITA collaboration team includes members from the University of Hawaii at Manoa, University of California, Los Angeles, The Ohio State University, The University of Delaware, The University of Kansas, Washington University, the NASA Jet Propulsion Laboratory, University College London, University of Chicago, National Taiwan University and the California Polytechnic State University.