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World’s Largest Ice Cube and Particle
Detector
by Dr.
Robert Piccioni
Jan 18, 2011
On December 19th, 2010, construction was completed on the IceCube
Neutrino Observatory in Antarctica. A cube of Antarctic ice one
kilometer (ten football fields long) on each side has been instrumented
with over 5000 optical sensors to detect neutrinos coming from outer
space.
Neutrinos are the most elusive of all known subatomic particles. (When
we figure out what dark matter is, neutrinos may take second place.)
Fifty trillion neutrinos zip right through each of us every second, and
only one per week actually interacts with the atoms in our bodies. A
neutrino can easily pass straight through a trillion miles of lead,
with only a 10% chance of “hitting” any of the lead atoms.
Neutrinos come primarily from the Sun, but also from supernovae and
other spectacular cosmic events. Because they are almost unstoppable,
we hope to use them to look where light cannot penetrate. For example,
it takes thousands of years for photons (particles of light) to travel
from our Sun’s core to its surface, as they are continually absorbed
and re-emitted. But neutrinos blast straight through, reaching Earth in
just over eight minutes. By using neutrinos, we can monitor the Sun’s
energy production in real time and be forewarned of coming changes in
the amount of sunlight we will receive. Neutrinos will also give us an
inside view of how stars explode. Even though supernovae can be
billions of times brighter in visible light than our Sun, we believe as
much as 99% of all their explosive energy is in neutrinos. IceCube will
let us see all we’ve been missing.
Antarctic ice is well-suited to making a neutrino detector, providing
an enormous mass that is ultra transparent. If a neutrino does hit an
atom in the ice, there might be a small flash of light that the sensors
will detect from as much as 100 yards away. A high-energy neutrino may
produce a trail telling us where it came from and what its energy was.
Hopefully this will add a new dimension to our understanding of the
universe.
IceCube was
constructed by drilling 86 holes, each 1.5 miles deep, into the
Antarctic plateau at the South Pole, 800 miles south of McMurdo Station
near the coast. The University of Wisconsin-Madison leads this project
and developed a special 4.8 megawatt hot-water drill. Each completed
hole was equipped with a string of 64 sensors before being allowed to
refreeze. Construction began in 2006 and operated round the clock
during the short Antarctica summer, when the Sun shines 24 hours a day.
IceCube is an international collaboration, but the U.S. has provided
87% of the project’s $279 million cost.
IceCube is expected to observe 100 neutrino interactions per day, and
has already recorded one with over 100 trillion electron-volts of
energy, seven times the highest energy expected from the largest
man-made particle accelerator, the LHC near Geneva.
We look forward to IceCube discoveries that are really cool.
Enjoy
Exploring.
Best Regards,
Robert
Dr Robert Piccioni,
Author of "Everyone's
Guide to Atoms, Einstein, and the Universe"
and "Can Life Be Merely An Accident?"
www.guidetothecosmos.com
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