Polar neutrino observatory takes a big step forwardMarch 22, 2006An 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 kilometer 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," says 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 optimize 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 kilometer 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. 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," says Halzen. "They perform like a Swiss watch. But the big story of this season is the performance of the drill." 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. Even so, "all the major challenges encountered by drilling a first hole last season have been solved," says 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, according to Jim Yeck, IceCube project director. "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," Yeck says. The newly installed modules are functioning and sending signals to the surface, Yeck says. IceCube scientists will continue to verify cable connections and surface electronics during the upcoming winter season at the South Pole. University of Wisconsin-Madison |
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| Related Neutrino Current Events and Neutrino News Articles Kraken becomes first academic machine to achieve petaflop The National Institute for Computational Sciences' (NICS's) Cray XT5 supercomputer-Kraken-has been upgraded to become the first academic system to surpass a thousand trillion calculations a second, or one petaflop, a landmark achievement that will greatly accelerate science and place Kraken among the top five computers in the world. Invading black holes explain cosmic flashes Black holes are invading stars, providing a radical explanation to bright flashes in the universe that are one of the biggest mysteries in astronomy today. To understand the universe, science calls on the ultrasmall Will the universe expand outward for all of eternity and end in a vast, dark, cold, sterile, diffuse nothingness? Or will the "Big Bang" - the gargantuan explosion that formed the universe 14 billion years ago - end in the "Big Crunch?" UD researchers focus on building telescope at South Pole It's 40 degrees F below zero (with the wind chill) at the South Pole today. Yet a research team from the University of Delaware is taking it all in stride. Einstein's relativity survives neutrino test Physicists working to disprove "Lorentz invariance" -- Einstein's prediction that matter and massless particles will behave the same no matter how they're turned or how fast they go -- won't get that satisfaction from muon neutrinos, at least for the time being, says a consortium of scientists. Supernova birth seen for first time Astronomers have seen the aftermath of spectacular stellar explosions known as supernovae before, but until now no one has witnessed a star dying in real time. Physicists: After 30 years of study, rare particle confirms prediction High-energy physicists devoted to recreating the conditions at the beginning of the universe have for the first time observed a new way to produce those basic particles of atoms, protons and neutrons. Researchers detect low-energy neutrinos, probe energy production in sun's center In collaboration with scientists from institutions in the United States and Europe, researchers from Virginia Tech have observed tell-tale signals of neutrinos emitted by thermonuclear fusion reactions that power the sun deep in its interior. Catching Some Rays An international team of researchers has detected low-energy solar neutrinos--subatomic particles produced in the core of the sun--and measured in real-time the rate the particles hit our planet. Princeton scientists confirm long-held theory about source of sunshine Scientists are a step closer to understanding sunshine. A monumental experiment buried deep beneath the mountains of Italy has provided Princeton physicists with a clearer understanding of the sun's heart -- and of a mysterious class of subatomic particles born there. More Neutrino Current Events and Neutrino News Articles |
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