IceCube neutrino observatory nears completion

Aug 31, 2010
Signals from the sensors are carried by cables to the IceCube counting house that houses a large cluster of computers to reconstruct in real time some 2,000 muon tracks every second. Credit: J. Haugen

In December 2010, IceCube -- the world's first kilometer-scale neutrino observatory, which is located beneath the Antarctic ice -- will finally be completed after two decades of planning. In an article in the AIP's Review of Scientific Instruments, Francis Halzen, the principal investigator of the IceCube project, and his colleague Spencer Klein of Lawrence Berkeley National Laboratory provide a comprehensive description of the observatory, its instrumentation, and its scientific mission -- including its most publicized goal: finding the sources of cosmic rays.

"Almost a century after their discovery, we do not know from where the most to hit the Earth originate and how they acquire their incredible energies," says Halzen, a professor of physics at the University of Wisconsin in Madison.

After light, , which are created in the decay of radioactive particles, are the most abundant particles in the universe. High-energy neutrinos are formed in the universe's most violent events, like exploding stars and gamma ray bursts. Because the neutrino has no charge, essentially no mass, and only interacts weakly with matter, trillions of neutrinos pass through our bodies each day, without effect. On extremely rare occasions, a neutrino will strike the nucleus of an atom, creating a particle, called a muon, and blue light that can be detected with optical sensors. The trick is spying those collisions—and, in particular, the collisions of high-energy neutrinos. IceCube does it by sheer virtue of its size.

IceCube scientists deploy a calibration light source, called the Standard Candle in one of the 2.5 km deep holes. Each of the 86 holes contains a string of 60 Digital Optical Modules (DOMs) that detect the blue light from neutrino events in the deep, clear ice. Credit: J. Haugen

At 1 kilometer on a side -- with 5,160 occupying a gigaton of ice -- the observatory is orders of magnitude bigger than other neutrino detectors; the Superkamiokande detector in the Japanese Alps, for example, is only 40 meters on a side.

" has been totally optimized for size in order to be sensitive to the very small neutrino fluxes that may reveal the sources of cosmic rays and the particle nature of dark matter," Halzen says.

Explore further: Microscopic "walkers" find their way across cell surfaces

More information: The article, "IceCube: An instrument for neutrino astronomy" by Francis Halzen and Spencer R. Klein appears in the journal Review of Scientific Instruments. See: rsi.aip.org/resource/1/rsinak/v81/i8/p081101_s1

Provided by American Institute of Physics

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User comments : 9

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AkiBola
1.4 / 5 (11) Aug 31, 2010
Awesome. I wonder if they can find Obama's birth certificate and college transcripts too?
feynmansum
3.8 / 5 (10) Aug 31, 2010
Perhaps a better question is, will the neutrinos prove as elusive as your high school diploma?
questioner
not rated yet Sep 01, 2010
i like how they say at no affect what if we cant detect the affects, as seeing we dont understand them so well? have any neutrinos been detected at that other place they mentioned?
MaxwellsDemon
5 / 5 (4) Sep 01, 2010
@questioner - The original Kamiokande detector not only worked at detecting neutrinos, it proved that the Sun is a source of them, and its successor the Superkamiokande detector gave us the first evidence of neutrino oscillation - which was the first empirical proof we had that the Standard model is flawed.

And its true that we could understand neutrinos and other particle interactions better, that's why scientists go to such extravagant lengths to stretch the boundaries of engineering even in the most hostile environments on the planet and in space.

A project of this epic scale will very likely answer one or two of its mission questions, and if we're lucky it'll raise some even more interesting questions in the process. Have a hot cocoa on me, boys!
AkiBola
1.5 / 5 (6) Sep 01, 2010
Perhaps a better question is, will the neutrinos prove as elusive as your high school diploma?


It's not my fault you are too incompetent to find it :)
feynmansum
3.3 / 5 (3) Sep 01, 2010
I wonder if they can find Obama's birth certificate and college transcripts too?


It's not my fault you are too incompetent to find it :)


Ah, an internal Socratic dialogue! Well done, I take back my jab about your diploma.

tkjtkj
not rated yet Sep 01, 2010
It's my understanding that this detector was constructed in the anarctic because there it can use the earth itself as a filter. Only neutrinos can penetrate the earth unscathed.
However, if they dont know from where the neutrions are coming, why did they assume that the best direction to look was in the sky of the northern hemishere?
Surely any place on earth would do , and no doubt for a lot less money .. Unless drilling in ice is a very cheap endeavor.
Ideas??
and do please email:
tkjtkj@gmail.com
ADDENDUM:
actually, perhaps i can second guess my previous question:
for constant viewing, yes, it'd have to be at one of the earth's poles , to avoid rotational effects. And the south pole is drillable, whereas the north one is not..
Could it be so simple?
astounded1
not rated yet Sep 05, 2010
Can anyone tell me why they don't just do this in the ocean? Would it not be cheaper to place the detectors on the bottom of the ocean rather than drill all those holes in the ice. And if the issue is a polar location, well the arctic is available....
yyz
5 / 5 (1) Sep 05, 2010
"Can anyone tell me why they don't just do this in the ocean?"

They already do!

Among those operating, three are located in the Mediterranean Sea:

ANTARES http://antares.in...dex.html

NESTOR http://www.nestor.noa.gr/

and NEMO. A detector with a cubic kilometer detector in the Med is also planned (KM3NeT http://www.km3net.org/home.php ). These observatories carry on the search for discrete neutrino sources and are complementary to IceCube.