A A ntarctic M M uon A A nd N N eutrino D D etector A A rray

Most telescopes look up. This one looks down. Most capture some sort of light. This one seeks an invisible subatomic particle. Most telescopes are in remote locations, but this one goes to extremes: it is buried under more than a mile of ice at the South Pole. That’s the Eiffel Tower there, as a basis to compare… This is very big science.

AMANDA & IceCube are Neutrino Telescopes. They will be able to detect the arrival of neutrinos from the universe’s most energetic particle accelerator engines : Gamma-ray bursts, supernovae, active galactic nuclei, supermassive black holes. Neutrinos barely interact with ordinary matter ! This is great, because they arrive essentially unfiltered, with the same momentum they started with, long ago & far away. Other types of radiation like photons or charged particles, are more affected by the characteristics of the regions of space they pass through.But…. This is not great, because they are very difficult to catch ! So, you need a huge volume of ordinary matter filled with detectors to “see” a neutrino…. ICE !

AMANDA will look for neutrinos from distant energetic sources. On top of the South Pole ice, several types of detectors: IceTop, SPASE, VULCAN, will record the arrival of more “ordinary” particles from cosmic ray events in the Earth’s atmosphere. These instruments, while not able to give direct information about neutrinos, can provide a kind of filter on AMANDA data, so that only distant-source neutrino events are collected. The Antarctic Muon and Neutrino Detector Array (AMANDA) is the world's largest detector of the mysterious neutrino--and the first that can claim to be an astronomical instrument rather than a physics experiment.

So far the observatory, a $7-million collaboration among U.S., Belgian, Swedish and German universities, consists of 424 glass orbs, each the size of a basketball. Each orb contains a photomultiplier tube, which can “see” even a single photon and give out an electronic signal.

The Photomultiplier tubes watch for the eerie blue glow, called Cerenkov light, emitted when neutrinos interact with atomic nuclei in the ice or underlying rock. Cerenkov photons are emitted by atoms as faster-moving particles pass them by, in a process similar to the shockwave created by a supersonic airplane. Cerenkov light from extraterrestrial sources is too faint to be seen with the human eye. There are detectors which search for Cerenkov light in the air, also, but the ice is ideal because it’s so deep, dense, clear, and stable. The orbs point downward so that Earth will screen out extraneous particles.

To deploy the chain of orbs, workers first used pressurized hot water to melt a column of ice half a meter across and 2,400 meters deep. Drilling equipment now prepares each hole in about 48 hours.

It takes nearly 8 hours to deploy a 750 meter string of cables with optical orbs attached. As the video camera attached near the bottom of the chain descends, the quality of the ice changes, becoming very clear and reflective. The high optical clarity of the deep ice is crucial to the success of the project.

It turns out that ice is a friendly place for neutrino detectors. At depth it is crystal-clear, so the orbs can spot flashes of light hundreds of meters away. AMANDA exemplifies a new breed of telescope that has redefined what it means to "see."

Working with drilling equipment under the ultra-cold conditions presents unusual equipment and safety considerations. One worker put a key in her mouth for a moment while she was taking off her outer gloves in order to work a lock. The key froze to her lips...

AMANDA & its successor, ICE CUBED, are the largest single US project on the continent. Enormous amounts of material and personnel are airlifted in, and construction has already consumed 7 years.

The construction season is very short during the polar summer, and crews put in long work days. The perpetual daylight helps keep things moving.

The last chain of the season is cause for a photo opportunity. The team has lowered in the orbs, strung on a cable like beads on a necklace, and let them freeze in place. Ultimately, scientists want 5,000 orbs on 80 cables throughout a cubic kilometer of ice.

A frivolous touch : on the last chain of the season, one of Antarctica’s native pink flamingos is lowered to an icy tomb 600 m below the surface.

The reservoir of hot water for drilling can be be put to other uses, also. This is very welcome, as water for showers & bathing is strictly rationed.

At present, AMANDA is 17 strings of 60 modules, 16 meters apart. IceCube will add 63 more strings, for a cubic kilometer of detector. Total cost : approximately $ 140,000,000. The work will be spread out over 6 summer seasons starting in IceCube will operate in coincidence with a new generation of “telescopes” like LIGO and GLAST to examine energetic across bandwidths far beyond normal human experience…