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The University of Delaware is helping to build a huge IceCube at the South Pole, and it has nothing to do with cooling beverages.
IceCube is a gigantic scientific instrument--a telescope for detecting illusive particles called neutrinos that can travel millions of miles through space, passing right through planets.
A poet might refer to them as stardust or ghosts from outer space. But to astrophysicists, neutrinos are the high-energy messengers from the universe, formed during such cataclysmic cosmic events as exploding stars and colliding galaxies.
When the novel telescope is completed in the next several years, a cubic kilometre of ice at the bottom of the world will provide a new eye into the heavens and some of the most distant and violent events in the cosmos.
The telescope, its third year of construction recently concluded, is an international effort involving more than 20 institutions. The project is funded primarily by the National Science Foundation, with additional contributions from Belgium, Germany, Japan and Sweden, as well as the U.S. Department of Energy and the Wisconsin Alumni Research Foundation.
The lead institution for the IceCube project is the University of Wisconsin, which is working in collaboration with University of Delaware† and several other universities across the nation.

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†As the austral summer wanes, so does the highly successful 2006-07 work season at the IceCube Neutrino Observatory in Antarctica, which draws to a close Thursday, Feb. 15.

During a productive season, scientists and engineers successfully positioned 13 strings of optical sensors deep in the polar ice. Each string carries 60 of the digital optical modules (DOMs), which are designed to capture evidence of highly energetic and elusive subatomic particles called cosmic neutrinos. This year's efforts more than doubled the number of installed DOMs to a total of 1,320, roughly one-fourth of the 4,800 sensors that will ultimately make up the IceCube Neutrino Observatory when it is completed in 2011.

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Title: Icecube, the World's Largest Dark Matter Detector
Authors: Hagar Landsman (for the IceCube collaboration)

IceCube is a kilometre scale high-energy neutrino observatory, currently under construction at the South Pole. It is a photo-detector, using the deep Antarctic ice as detection medium for the Cherenkov photons induced by relativistic charged particles. These charged particles may be atmospheric muons or reaction products from neutrino interactions in the vicinity of the instrumented volume. The experiment searches for neutrinos originating in astrophysical sources, and can also detect neutrinos from WIMP interaction in the Sun or Earth. In the last two austral summers, 9 in-ice strings and 16 surface IceTop stations (out of up to 80 planned) were successfully deployed, and the detector has been taking data ever since. In this proceedings, IceCube design, present status, performance and dark matter detection sensitivities will be discussed.

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Neutrino astronomy
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Title: Neutrino astronomy with IceCube and AMANDA
Authors: Gary C. Hill, for the IceCube collaboration

Since the early 1990s, the South Pole has been the site of the construction of the world's first under-ice Cherenkov neutrino telescopes - AMANDA and IceCube. The AMANDA detector was completed in 2000, and its successor IceCube, a kilometre scale neutrino detector, began construction in 2005. Completion of IceCube is scheduled for 2011. This paper will give an overview of the history, construction, latest physics results and potential of these detectors.

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Title: IceCube: Performance, Status, and Future
Authors: Carsten Rott, for the IceCube Collaboration

High-energy neutrinos are uniquely suited to study a large variety of physics as they traverse the universe almost untouched, in contrast to conventional astronomical messengers like photons or cosmic rays which are limited by interactions with radiation and matter at high energies or deflected by ambient magnetic fields. Located at the South Pole, IceCube combined with its predecessor AMANDA comprise the world's largest neutrino telescope. IceCube currently consists of nine strings, each containing 60 digital optical modules, deployed at depths of 1.5 to 2.5km in the ice and an array of 16 surface air-shower stations. IceCube is expected to be completed in early 2011 at which time it will instrument a volume of one km≥ below the IceTop air-shower array covering an area of one km≤. The current IceCube detector performance is described and an outlook given into the large variety of physics that it can address, with an emphasis on the search for ultra-high-energy neutrinos which may shed light on the origins of the highest energy cosmic rays.

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AMANDA
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Title: Neutrino detectors in ice: results and perspectives
Authors: Adam Bouchta, for the IceCube Collaboration

The AMANDA neutrino detector has been in operation at the South Pole for several years. A number of searches for extraterrestrial sources of high energy neutrinos have been performed. A selection of results is presented in this paper. The much larger IceCube detector will extend the instrumented ice volume to a cubic kilometre and 9 out of 80 planned IceCube strings have been deployed to date.
Researchers present the status for both detectors.

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IceCube
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POLAR NEUTRINO OBSERVATORY TAKES A BIG STEP FORWARD

An international team of scientists and engineers has taken a major step toward completion of what will be the world's preeminent cosmic neutrino observatory, harnessing a sophisticated hot-water drill to build an observatory under the South Pole that eventually will encompass a cubic kilometre of ice.

Scientists leading a consortium building the massive neutrino telescope known as IceCube say that this year they have nearly doubled the size of the detector now under construction at the National Science Foundation's Amundsen-Scott South Pole Station.

NSF, through a joint program of its Office of Polar Programs and its Mathematical and Physical Sciences Directorate, is contributing more than $240 million to the international partnership that is building the detector, which will cost $272 million overall.
Although work can only take place from October through February-the fleeting and still frigid summer season at the Pole-the extent and pace of construction this year means that the observatory may soon begin scientific operations. IceCube is scheduled for completion in 2011.

"The news is good all around" - Francis Halzen, the University of Wisconsin-Madison physics professor leading the effort.

Halzen and others leading the effort report that IceCube- which depends on strings of light-sensing modules frozen deep in crystal clear Antarctic ice-has grown this austral summer by 480 basketball-sized optical modules. Deployed on long cables in 1.5-mile deep holes bored by a unique hot-water drill, the modules will be used to detect the fleeting but telltale signatures of high-energy cosmic neutrinos as they flit through the Earth.
Neutrinos are ghostly, high-energy subatomic particles created in galactic collisions, distant black holes, quasars and a zoo of the most violent events in the cosmos. They carry information that promises to peel back some of the mystery of the universe's most enigmatic events such as gamma ray bursts, dark matter and supernovas.
But cosmic neutrinos-billions of which pass unnoticed through the Earth and indeed through the human body every day-are, by their very nature, extremely difficult for astrophysicists to detect. What is required is a very large detector to optimise the chances that scientists can catch a neutrino in the act of crashing into a proton or another subatomic particle.
When IceCube is completed, a cubic kilometre of the ice beneath the Pole will have been seeded with more than 4,200 optical sensors to capture telltale traces of the neutrinos and follow their tracks back to their distant points of origin. In addition, another 300 or so sensors will be deployed in tanks on the surface of the polar ice.
Once the holes are drilled, cables with the spherical digital optical modules-which are composed of electronics for sensing light and circuit boards for gathering and processing data-are lowered into the ice, where they are frozen in place. The modules act like light bulbs in reverse, gathering light created when neutrinos collide with other particles. The modules then relay data to the surface where the information is processed and stored for analysis.
When fully operational, IceCube will sample neutrinos from the sky in the Northern Hemisphere. The detector will use the Earth as a filter to exclude other types of neutrinos, such as those from the sun, which could confuse the detector. Its primary scientific mission will be to identify the sources and distribution of the highest energy neutrinos created by violent cosmic events.

IMAGE
Expand (1.6mb, 1199 x 2100)
A specialised drill head used to melt snow at the surface of the South Pole is deployed as scientists prepare to drill a 1.5 mile deep hole in the Antarctic ice. Known as the firn drill, the device melts surface snow that has not yet been turned to clear ice in preparation for a novel hot-water drill used to make the deep holes in which long strings of light sensors are deployed. The international project, led by UW-Madison physics Professor Francis Halzen, made significant progress this austral summer, adding 480 basketball-sized optical modules used to track signs of cosmic neutrinos. When completed, the neutrino observatory will occupy a cubic kilometre of Antarctic ice, and will be the world's largest scientific instrument.
Image courtesy: courtesy Ice Cube Project


IceCube is being constructed around an older, prototype neutrino telescope known as AMANDA for Antarctic Muon and Neutrino Detector Array. IceCube construction began in January 2005 when scientists drilled the first hole for the detector and deployed the first optical modules for the observatory.

"The digital optical modules deployed last year have now functioned for one year without failures. They perform like a Swiss watch. But the big story of this season is the performance of the drill" - Francis Halzen.

After working out kinks in the performance of the drill last year and at the beginning of the 2005-06 drilling season, and adding an extra drilling tower, the IceCube team was able this year to bore a total of eight deep holes into the Antarctic ice and deploy eight 60-module strings of sensors this season. Combined with the existing AMANDA array, IceCube currently consists of nearly 1,300 optical modules.
Although the new technologies used to create the detector are completely environmentally safe, the engineering challenges of working in the Polar environment-where temperatures fluctuate, on average, from minus 35 Fahrenheit in November to minus 16 Fahrenheit in February-are daunting.

"All the major challenges encountered by drilling a first hole last season have been solved" - Francis Halzen.

The IceCube array now is composed of nine strings and 16 surface detector stations, in addition to the still operational AMANDA array, making a scientific program possible.

"We know that there is more work to be done, but let there be no doubt about what a remarkable accomplishment it is to safely install eight strings this season" - Jim Yeck, IceCube project director.

The newly installed modules are functioning and sending signals to the surface. IceCube scientists will continue to verify cable connections and surface electronics during the upcoming winter season at the South Pole.
IceCube is an international collaboration of scientists from more than 30 scientific organizations. It is supported primarily by NSF, with significant contributions from Germany, Sweden, Belgium, Japan, New Zealand, and the Netherlands. The project has also received significant support from the Wisconsin Alumni Research Foundation.

Scientists collaborating on IceCube include researchers from UW-Madison, the University of California at Berkeley, the University of California at Irvine, the Lawrence Berkeley National Laboratory, the University of Maryland, Penn State University, the University of Wisconsin-River Falls, the University of Delaware, the University of Kansas, Clark Atlanta University, Southern University, the University of Alaska, and the Institute for Advanced Study at Princeton University.

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-- Edited by Blobrana at 03:14, 2006-03-22

-- Edited by Blobrana at 10:17, 2007-05-24

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