Polar Telescope Sights First High-Energy Neutrinos

Writing in the March 22 edition of the British scientific journal Nature, an international collaboration of physicists and astronomers reports the first observation of high-energy neutrinos using the AMANDA Telescope, a large array of buried detectors designed to detect the fleeting signs of high-energy subatomic particles from the farthest reaches of space.

"We have proven the technique," says Francis Halzen, a University of Wisconsin-Madison professor of physics and the lead author of the Nature paper. "We have a unique probe with a sensitivity well beyond other experiments, and the neutrinos we've seen are of a higher energy than has been seen before."

Neutrinos are invisible, uncharged, nearly massless particles that can travel cosmological distances. Unlike the photons that make up visible light, or other kinds ofradiation, neutrinos can pass unhindered through stars, vast magnetic fields and entire galaxies without skipping a beat.

To be able to detect high-energy neutrinos and follow their trails back to their points of origin promises unparalleled insight into such extraordinary phenomena as colliding black holes, gamma-ray bursters, the violent cores of distant galaxies and the wreckage of exploded stars.

Of all high-energy particles, only neutrinos can directly convey astronomical information from the edge of the universe -- and from deep inside the most cataclysmic high-energy processes, notes Robert Morse, a UW-Madison professor of physics and the principal investigator for the AMANDA project.

Sunk more than one-and-a-half kilometers beneath the South Pole, the National Science Foundation-funded AMANDA Telescope is designed to look not up, but down, through the Earth to the sky in the Northern Hemisphere. Since neutrinos can and do skip through the Earth continuously, it is the logical direction to point the telescope in order to filter out other, confusing high-energy events. The Earth between the detector at the South Pole and the northern sky filters out everything but neutrinos.

The AMANDA telescope array consists of 677 optical modules, each the size of a bowling ball, arrayed on electrical cables set deep in the ice beneath the South Pole and arranged in a cylinder 500 meters in height and 120 meters in diameter.

The glass modules at the heart of AMANDA work like light bulbs in reverse, capturing the faint and fleeting streaks of light created when the occasional neutrino crashes head on into another part