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IceCube Project's First Season is Success
By Molly Exner
UW-RF News Bureau
MARCH 4, 2005--Working under harsh Antarctic conditions, an international
team of scientists, engineers and technicians has set in place the first
critical elements of a massive neutrino telescope at the South Pole, developed
by a team of academic institutions, including professors and students
from UW-River Falls.
In an announcement on Feb. 15, scientists and managers of the project
declared a successful first season of construction of what will become
the world’s largest scientific instrument. This year marks the first
year of work on the IceCube telescope, which is being built around a much
smaller neutrino telescope called AMANDA, Antarctic Muon and Neutrino
Detector Array.
The successful deployment in a 1.5 mile-deep hole drilled into the Antarctic
ice of a string of 60 optical detectors designed to sample phantom-like
high-energy particles from deep space represents a key first step in the
construction of the $272 million telescope.
Building the telescope requires drilling at least 70 half-mile deep holes
in the ice using a novel hot-water drill, and then lowering long strings
of volleyball-sized optical detectors--4,200 in all--into the holes where
they will be frozen in place. The first string of 60 detectors was lowered
into the ice in January and communication with the detectors was successful.
Establishing the project at the South Pole, setting surface equipment
in place and testing the powerful new drill meant the team had only a
two-week window to drill the first hole and deploy the first IceCube string.
Next year, with a full Austral summer season of about six weeks, the goal
will be to drill holes and deploy ten or more strings.
"It's all on track," according to Francis Halzen, a UW-Madison
phyiscs professor and principal investigator for the project. "This
was our first exam. We met our milestones for the season and we can move
on to the next Antarctic summer. "
UW-River Falls physics Professor Jim Madsen says he's excited to have
this phase completed. "This has been such a huge challenge because
it's new and nothing of this size has ever been done before."
UW-RF's Role
UW-RF has played an active role in helping the IceCube Project become
a working reality. The University has been responsible for creating 1,000-gallon
water-tanks installed with two light sensors, identical to those deployed
deep within the icecap, frozen in the tanks.
UW-RF physics students have been actively working on various aspects of
the project for the past year or more, including Luke Chambers, a senior
from Hugo, Minn.; Jonathan Eisch, a senior from Wisconsin Rapids, Wis.;
Allen Riley, a junior from Hudson, Wis.; Michael Tate, a junior from Muskego,
Wis.; and Jeremy Tilsen, a senior from Hudson, Wis.
Eisch traveled to the South Pole last year to help deploy prototype tanks
in preparation for this season's work, and he spent this past summer with
Tilsen on a research internship at the University of Delaware helping
construct the eight tanks recently installed at the South Pole.
Two out of eight tanks developed by UW-RF were installed this past summer
at the South Pole (November, December and January when flights are able
to get in and out of the pole). Two tanks are deployed on the surface
above each IceCube hole. Madsen says, "The nice thing is that all
of the eight tanks that UW-RF has worked on have been successful."
Wrapped around a framework above the tanks are "sunshades" to
keep direct sunlight from hitting the top of the water, since at the South
Pole the sun simply circles around the sky while staying essentially the
same distance above the horizon day after day, finally setting near March
21 and not rising again until Sept. 21.
The "sunshades" were designed by UW-RF physics Assistant Professor
Glenn Spiczak, along with Madsen and Tate. The shades were sewn by Carol's
Alterations, a tailoring shop located in River Falls, Wis., making the
River Falls connection more and more dominant in the exciting project,
Spiczak says.
Spiczak says the shades play an important part in making the rest of the
process possible. "The 'sunshades' allow the water to freeze more
rapidly, a surprising problem even at the South Pole. Because of the rather
large thermal heat capacity of water it takes roughly two months for the
entire tank to freeze."
According to Spiczak, roughly 160 of these tanks will be installed over
the next several years and spread out over a square-kilometer area above
the cubic-kilometer volume of instrumented ice below, completing the world's
largest neutrino telescope to study some of the most energetic phenomena
in the universe.
How It Works
When completed, the telescope will utilize a cubic kilometer of Antarctic
ice as a detector, and will be capable of capturing information-laden,
high-energy particles from some of the most distant and violent events
in the universe. It promises a new window to the heavens and may be astronomy’s
best bet to resolve the century-old quest to identify the sources of cosmic
rays.
The IceCube telescope will look for the telltale signatures of high-energy
cosmic neutrinos, ghostlike particles produced in violent cosmic events
-- colliding galaxies, distant black holes, quasars and other phenomena
occurring at the very margins of the universe. Cosmic rays, which are
composed of protons, are thought to be generated by these same events.
But protons are bent by the magnetic fields of interstellar space, preventing
scientists from following them back to their points of origin.
Cosmic neutrinos, on the other hand, have the unique ability to travel
cosmoogical distances without being absorbed or deflected by the stars,
galaxies, and interstellar magnetic fields that permeate space. Their
ability to skip through matter without missing a beat promises unedited
information about the early universe and the very violent objects that
populate deep space.
The optical modules that make up the detector act like light bulbs in
reverse. They are able to sense the fleeting flash of light created when
neutrinos passing through the Earth from the Northern Hemisphere occasionally
collide with other atoms. The subatomic wreck creates another particle
called a muon. The muon leaves a trail of blue light in its wake that
allows scientists to trace its direction, back to a point of origin, potentially
identifying the cosmic accelerators--black holes or crashing galaxies,
for example--that produce the high-energy neutrinos.
An International Collaborative Effort
The telescope project is an international effort involving more than 20
institutions. The project is funded by the U.S. National Science Foundation,
with significant contributions from Germany, Sweden, Belgium, Japan, New
Zealand, the Netherlands, and the Wisconsin Alumni Research Foundation.
The NSF is providing $242 million with $30 million from foreign partners.
In the U.S., the project involves scientists from UW-RF, UW-Madison, the
University of California at Berkeley, the Lawrence Berkeley National Laboratory,
the University of Maryland, Penn State University, the University of Delaware,
the University of Kansas, the University of Alabama, Clark Atlanta University,
Southern University and A&M College, and Princeton University’s
Institute for Advanced Study.
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Last updated:
Tuesday, 22-Jun-2010 16:21:20 CDT
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