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Photo: ANITA collaboration |
ANITA takes flight
A one-time visitor to SLAC, the Antarctic Impulsive Transient Antenna (ANITA), recently took to the frigid skies over Antarctica on a mission looking for evidence of cosmic-ray neutrinos.
On December 14, 2006, scientists tethered the 20-foot-tall probe to a high-altitude helium balloon and released it into the atmosphere. ANITA circled the south polar continent three and a half times at an altitude of more than 100,000 feet—three times as high as a passenger jet. The probe's array of antennae was tuned to scan for the radio signals that are produced when cosmic-ray neutrinos strike the Antarctic ice below. ANITA landed nearly 1100 miles from the original launch site on January 19, 2007, after 35 days aloft—the second longest duration for a scientific balloon flight in history.
Before traveling to Antarctica, ANITA first got its bearings during calibration tests at SLAC. In early June 2006, a team of collaborators tuned the antennas with a series of experiments conducted in End Station A using a 10-ton block of ice to simulate the Antarctic environment. Researchers then blasted the ice with pulses of electrons, producing a cascade of radiation called Cerenkov radiation, which included both radio waves and visible light.
Brad Plummer
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