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
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!
No comments:
Post a Comment