Building a Telescope at the South Pole – Drilling into Ice
December 15, 2008
It's 40 degrees F below zero with
the wind chill at the South Pole today. Yet, a research team from the University of Delaware is taking it all in stride.
The physicists, engineers and
technicians from the University of Delaware's Bartol Research Institute are part of an
international team working to build the world's largest neutrino telescope in
the Antarctic ice, far beneath the continent's snow-covered surface. Dubbed
"IceCube," the telescope will occupy a cubic kilometer of Antarctica when it is completed in 2011, opening super-sensitive new eyes into
the heavens.
"IceCube will provide
new information about some of the most violent and far-away astrophysical
events in the cosmos," says Thomas Gaisser, the Martin A. Pomerantz
Chaired Professor of Physics and Astronomy at the University of Delaware, and one of the project's lead scientists.
The University of Delaware is among 33 institutions worldwide that are contributing to the
National Science Foundation project, which is coordinated by the University of Wisconsin.
Besides taking a turn as "on-ice lead" for
this year's IceCube construction effort at the South Pole (or simply
"Pole," as the locals call it), Gaisser is managing the University of
Delaware's continued deployment of the telescope's surface array of detectors,
known as "IceTop."
A Huge Telescope in the Ice
Rather than a giant lens
aimed at the heavens, the IceCube telescope consists of kilometer-long strings
of 60 optical detectors frozen more than a mile deep in the Antarctic ice like
beads on a necklace. Atop each string of deep detectors sits a pair of
600-gallon IceTop tanks, each containing two optical detectors.
Ironically, it takes about seven
weeks for the water in the IceTop tanks to freeze perfectly, without bubbles or
cracks, which could obstruct the tiny flash that occurs when particles pass
through the ice.
Neutrinos are among the most
fundamental constituents of matter. Because they have no electrical charge and
interact only weakly, these particles can travel millions of miles through
space.
Neutrinos can pass right
through planets, and they can emerge from deep inside regions of intense
radiation, such as the accretion disk around a massive black hole.
The surface IceTop detectors
measure cascades of particles generated by high-energy cosmic rays showered
down from above, while the detectors deep in the ice monitor neutrinos passing
up through the planet from below.
When a flash of light is
detected, the information is relayed to the nearby IceCube Lab, where the path
of the particle can be reconstructed and scientists can trace where it came
from, perhaps an exploding star or a black hole.
For Gaisser, this great quest
to capture neutrinos is a cosmic journey in more ways than one.
"All of my career at Bartol Research Institute
at the University of Delaware has been to study high-energy particles from
space," Gaisser says. "This experiment we're building fulfills all of
my dreams. Besides, it's fun to work here," he notes.
Drilling in the Deep Freeze
A drill camp supports each
season of the IceCube project in the 24-hour daylight of the Antarctic summer.
Drilling is a 24/7 operation with three shifts of drillers.
In the subfreezing
temperatures and howling winds, fuel tanks supply generators that make
electricity, which is used to heat the water that pulses through the
high-pressure hoses that melt the mile-and-a-half-long deep holes into which
strings of optical detectors are submerged.
The IceTop team works six days a week from 8 a.m. to
6 p.m., retreating to the warmth of the new Amundsen-Scott South Pole Station,
to sleep, eat, and spend what little free time they have reading, watching
movies, exercising or chatting with fellow "Polies."
|