Sunday, January 11, 2015
ANITA flies again
The ANITA balloon-born neutrino detection experiment has just finished its third flight. It flew for 22 days, 9 hours, during which time it circled Antarctic about 1 1/3 times.
ANITA floats high in the atmosphere (usually more than 100,000 feet), while it's 32 horn antennas look for radio waves from neutrino interactions in the Antarctic ice. Because of its height, it can scan an enormous volume of ice, out to the horizon, up to 600 km away. However, because of the distance to the interactions, it has a pretty high energy threshold, above 10^19 eV (roughly 100 times higher than ARIANNA). In its previous two flights, it did not see any neutrino interactions, but it did set some of the best current limits on ultra-high energy cosmic neutrinos. They also observed pulses which they attribute to coming from cosmic-ray air showers.
For the third (and what was planned to be the last) flight, the collaboration made a number of improvements to increase the experiments sensitivity, including the addition of a large, lower-frequency antenna, which be stowed for take-off and then released in-flight to hang below the balloon.
This flight was shorter than the previous flights; the second (ANITA-II) flight lasted 31 days, while the first flight was 35 days. NASA has a nice web-page showing the ANITA flight track. So, although the detector may have been more sensitive, this flight is unlikely to dramatically improve the overall ANITA sensitivity.
Katie Mulrey has written a couple of nice blog posts about the ANITA pre-flight preparations. They are here and here
I'm eagerly looking forward to hearing more about how the flight went, and how the data looks.