ICE CUBE Completed

Yes, we actually built this device and we will soon beseeing information flow in from this. This is a wow that compares nicely with CERN in terms of big scienceresearch. 

There is sometimes no other way except to go out and spendthe big bucks.  Today those big bucksseem a little easier to eat than even a decade ago.

I guess that for our next trick we need to build one in Greenland and take a look in the other direction.  Perhaps next century!

Posted by Dan Satterfield
22 DECEMBER 2010

One of the deep holes at the SouthPole that make up Ice Cube. Amundsen-Scott Station is in the background. Dan'spic Jan. 2010

It’scalled ICE CUBE and it’s at the bottom of the World. Actually it’s IN thebottom of the World, and without doubt it’s the strangest telescope on Earth.

Ice Cube is HUGE. Thedetectors are frozen for centuries in the polar ice cap.

Ice Cubeis a neutrino observatory. It’s made up of hundreds of detectors embedded inthe ice 1 km beneath the South Pole. My name is on one of those detectors, andit something I am very proud of!

The NSFannounced this week that the final detectors have been installed and Ice Cubeis officially complete. I visited last January as they were well underway.

Neutrinosare the smallest thing you cannot imagine. They are the tiniest wisp of nothingwe humans can contemplate. They are so small that billions are passing throughyour eyeball right now.

Not toworry, they will likely hit nothing. Most neutrinos pass through the entireEarth and hit nothing. They could pass through a light year thick slab of Leadand still most would not hit anything!

Do youbegin to understand what I mean when I say small?

Hoses carrying super hotwater are used to melt the ice and make deep holes to hold the detectors.

Neutrinoshave no charge like electrons and protons, and they do not interact withmatter. The only time we can observe one is when one just happens to crash intothe nucleus of an atom.

When that happens in ice, aparticle called a muon is ejected at nearly the speed oflight. The speed of light is slower in ice than in a vacuum, and if a particleis going faster than the light speed in ice, it produces a flash of blue lightcalled Cherenkov radiation. (Yes, nothing can go faster than the speed of lightin a vacuum, but particles can go faster than the speed of light in ice!)

The DOM (Digital OpticalModule) I signed. It's now frozen in the ice and a part of Ice Cube.

Bytracking the direction of the flashes of Cherenkov light researchers cancalculate backwards where the neutrino came from. They can also measure theintensity.

So whereare you going to find a 1km thick cube of clear pristine ice with thefacilities to house scientists and do research? The answer is easy, AmundsenScott Station at the South Pole.

This is the hole that holdsthe detector I signed.

Usingvery hot water, produced from melted ice, the ice cube folks have drilled abunch of deep holes in the ice. Then they lowered a string with specialdetectors on them into the ice. The detectors freeze into the ice and candetect flashes of light when a neutrino hits an atom. There are 80 holes with astring of 60 detectors called DOMS in each hole.

That’saround 4800 detectors! When I was at the Pole, I got to sign one. That detectorwith my name on it is now in the ice and part of Ice Cube.

Oh thethings that make a science geek smile!
Why areneutrinos so important? To answer that properly requires an expert to write agood book. Fortunately someone did and the book is a really interesting read.

FrankClose of Oxfordwrote NEUTRINO. You might think a book about a particle would be boring. It’snot! Frank Close tells an intriguing story of how science finally spotted one!

Neutrinosare made in stars, and they were made in the big bang when the universe was afraction of a second old. They are kind of like an astronomical X-ray. Theyallow astronomers to see into stars and through the gas and dust of theuniverse.

Below isa video clip I shot that gives a feel of the place.

Neutrinosare the subject of intense research right now and Ice Cube may very well makesome amazing discoveries that begin to answer some of the most weightyquestions in science. Think about it. 96% of the universe is made up of darkmatter and dark energy.

The exact bottom of theplanet is about a 5 min. walk from Ice Cube. It was -22F by the way and I hadmy coat off just long enough to take that pic.

It’scalled dark because we cannot see it and have no idea what it is! Only 4% ofthe universe is visible to us. Neutrinos may very well help scientists tofigure out what dark energy and dark matter really are. It’s a really big dealand you will understand how big, if you read the book.
You willalso know more about neutrinos than 99.9% of the people on Earth!

You can find out more aboutIce Cube here.

IceCube Explained

IceCube,a telescope under construction at the South Pole, will search for neutrinosfrom the most violent astrophysical sources: events like exploding stars, gammaray bursts, and cataclysmic phenomena involving black holes and neutron stars.The IceCube telescope is a powerful tool to search for dark matter, and couldreveal the new physical processes associated with the enigmatic origin of thehighest energy particles in nature. IceCube will encompass a cubic kilometer ofice and uses a novel astronomical messenger called a neutrino to probe theuniverse.

Neutrinosare produced by the decay of radioactive elements and elementary particles suchas pions. Unlike other particles, neutrinos are antisocial, difficult to trapin a detector. It is the feeble interaction of neutrinos with matter that makesthem uniquely valuable as astronomical messengers. Unlike photons or chargedparticles, neutrinos can emerge from deep inside their sources and travelacross the universe without interference. They are not deflected byinterstellar magnetic fields and are not absorbed by intervening matter.However, this same trait makes cosmic neutrinos extremely difficult to detect;immense instruments are required to find them in sufficient numbers to tracetheir origin.

IceCube Event Model

Althoughtrillions of neutrinos stream through your body every second, none may leave atrace in your lifetime. We actually use large volumes of ice below the SouthPole to watch for the rare neutrino that crashes into an atom of ice. Thiscollision produces a particle—dubbed a "muon"—that emerges from thewreckage. In the ultra-transparent ice, the muon radiates blue light that isdetected by IceCube's optical sensors. The muon preserves the direction of theoriginal neutrino, thus pointing back to its cosmic source. It is by detectingthis light that scientists can reconstruct the muon's, and hence theneutrino's, path. The picture is radically complicated by the fact that mostmuons seen by IceCube have nothing to do with cosmic neutrinos. Unfortunately,for every muon from a cosmic neutrino, IceCube detects a million more muonsproduced by cosmic rays in the atmosphere above the detector. To filter themout, IceCube takes advantage of the fact that neutrinos interact so weakly withmatter. Because neutrinos are the only known particles that can pass throughthe earth unhindered, IceCube looks through the earth and to the northernskies, using the planet as a filter to select neutrinos.

Sincethe 1950s scientists have built a compelling scientific case for doingastronomy and particle physics using high-energy neutrinos. The challenge hasbeen one of technology to build the kilometer-sized observatory needed to do thescience. Theorists anticipate that an instrument of this size is required tostudy neutrinos from distant astrophysical sources. Antarctic polar ice hasturned out to be an ideal medium for detecting neutrinos. It is exceptionallypure, transparent and free of radioactivity. A mile below the surface, bluelight travels a hundred meters or more through the otherwise dark ice. Frozenin the ice, IceCube not only will be the largest and most durable particledetector, but a real bargain at just 25 cents per ton!

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