Monday, January 3, 2011

ICE CUBE Completed

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

There is sometimes no other way except to go out and spend the big bucks.  Today those big bucks seem 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 South Pole that make up Ice Cube. Amundsen-Scott Station is in the background. Dan's pic Jan. 2010

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

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

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

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

Neutrinos are the smallest thing you cannot imagine. They are the tiniest wisp of nothing we humans can contemplate. They are so small that billions are passing through your eyeball right now.

Not to worry, they will likely hit nothing. Most neutrinos pass through the entire Earth and hit nothing. They could pass through a light year thick slab of Lead and still most would not hit anything!

Do you begin to understand what I mean when I say small?

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

Neutrinos have no charge like electrons and protons, and they do not interact with matter. The only time we can observe one is when one just happens to crash into the nucleus of an atom.

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

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

By tracking the direction of the flashes of Cherenkov light researchers can calculate backwards where the neutrino came from. They can also measure the intensity.

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

This is the hole that holds the detector I signed.

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

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

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

Frank Close of Oxford wrote NEUTRINO. You might think a book about a particle would be boring. It’s not! Frank Close tells an intriguing story of how science finally spotted one!

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

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

Neutrinos are the subject of intense research right now and Ice Cube may very well make some amazing discoveries that begin to answer some of the most weighty questions in science. Think about it. 96% of the universe is made up of dark matter and dark energy.

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

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

You can find out more about Ice Cube here.

IceCube Explained

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

Neutrinos are produced by the decay of radioactive elements and elementary particles such as pions. Unlike other particles, neutrinos are antisocial, difficult to trap in a detector. It is the feeble interaction of neutrinos with matter that makes them uniquely valuable as astronomical messengers. Unlike photons or charged particles, neutrinos can emerge from deep inside their sources and travel across the universe without interference. They are not deflected by interstellar 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 trace their origin.

IceCube Event Model

Although trillions of neutrinos stream through your body every second, none may leave a trace in your lifetime. We actually use large volumes of ice below the South Pole to watch for the rare neutrino that crashes into an atom of ice. This collision produces a particle—dubbed a "muon"—that emerges from the wreckage. In the ultra-transparent ice, the muon radiates blue light that is detected by IceCube's optical sensors. The muon preserves the direction of the original neutrino, thus pointing back to its cosmic source. It is by detecting this light that scientists can reconstruct the muon's, and hence the neutrino's, path. The picture is radically complicated by the fact that most muons seen by IceCube have nothing to do with cosmic neutrinos. Unfortunately, for every muon from a cosmic neutrino, IceCube detects a million more muons produced by cosmic rays in the atmosphere above the detector. To filter them out, IceCube takes advantage of the fact that neutrinos interact so weakly with matter. Because neutrinos are the only known particles that can pass through the earth unhindered, IceCube looks through the earth and to the northern skies, using the planet as a filter to select neutrinos.

Since the 1950s scientists have built a compelling scientific case for doing astronomy and particle physics using high-energy neutrinos. The challenge has been one of technology to build the kilometer-sized observatory needed to do the science. Theorists anticipate that an instrument of this size is required to study neutrinos from distant astrophysical sources. Antarctic polar ice has turned out to be an ideal medium for detecting neutrinos. It is exceptionally pure, transparent and free of radioactivity. A mile below the surface, blue light travels a hundred meters or more through the otherwise dark ice. Frozen in the ice, IceCube not only will be the largest and most durable particle detector, but a real bargain at just 25 cents per ton!

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