- Thousands of feet below the Earth's surface, scientists
around the world are happily engaged in studying the birth of our universe
and its possible destruction.
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- To properly study neutrinos -- those perky, almost invisible
particles carrying messages from deep outer space -- to fully explore the
cosmic mystery glue known as dark matter, to verify whether some rogue
nation is furtively developing nuclear weapons and testing them deep underground,
and to develop computer chips that don't contain flaws caused by subatomic
particles, scientists need to work in deep burrows beneath the Earth's
surface. They need to be far away from the bombardment of cosmic rays and
seismic noise that interferes with delicate experiments.
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- But there are no active deep laboratories in the United
States, so American scientists have to use facilities in Canada, Japan,
Russia and Italy.
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- That may be about to change. The National Science Foundation,
an independent agency of the U.S. government, has indicated that it is
interested in funding the development of a deep underground lab in the
United States, to be built in 2008. The NSF is expected to issue a formal
call for site proposals for the lab next month.
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- "Deep underground offers a unique environment to
listen to the universe and study the Earth," said Michael Turner,
NSF director of mathematical and physical sciences. "Such research
could go a long way to solving the riddle of the stuff that holds all structures
in the universe together."
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- 2008 can't come quickly enough for the scientists. Those
with limited travel budgets that don't allow jaunts to labs in other countries
often depend on the kindness of local mine owners, many of whom have allowed
the scientists to share their space. While grateful, scientists say the
working conditions in mines are less than ideal.
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- "Doing science underground in the U.S. usually means
working just like miners do," said University of Washington physicist
Wick Haxton. "Scientists would like better access to deeper, cleaner
and quieter spaces -- away from blasting, for example. This would make
our experiments much easier and less stressful, and we would also save
time and money."
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- The only big problem now -- besides getting Congress
to approve the many millions the underground lab will cost -- is where
to put it.
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- Last year, the NSF had indicated interest in converting
the now-closed Homestake gold mine in South Dakota's Black Hills into a
deep lab. Physics experiments had been conducted within Homestake, the
nation's deepest mine, for decades before the mine's owner announced Homestake
would close several years ago.
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- Homestake has already proven its fitness for science;
it was deep within the Homestake mine that neutrinos from the sun were
first detected by physicist Raymond Davis Jr. in 1965.
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- But the 8,000-foot-deep mine is slowly flooding since
its owner, the Barrick Gold Corp., turned off the underground pumps last
summer to save the $300,000 per month it was costing to keep the abandoned
mine dry. The water is currently above the 7,400-foot level, according
to Haxton.
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- Homestake may still be able to be pumped dry if it's
selected as the site for the lab, but scientists have recently proposed
several other sites, including a working limestone mine in southwestern
Virginia, a molybdenum mine west of Denver, a site under San Jacinto Mountain
in Southern California and another beneath the Cascade Mountains in eastern
Washington.
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- After receiving half a dozen unsolicited proposals in
favor of other locations over the past year, the NSF recently announced
that it would begin evaluating the other sites.
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- Haxton, with his University of Washington colleague John
Wilkerson, had originally supported the plan to locate the laboratory in
Homestake, but now wants to see the lab placed 7,700 feet under the Cascades.
The Cascade site would allow people and equipment to be driven down into
the laboratory through two tunnels, each 3 miles long, without the need
for complicated equipment transfers using costly hoists, said Haxton.
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- "This is the kind of laboratory that Italy built
at Gran Sasso, that the Russians built at Baksan and that the Japanese
have at Kamioka. Most scientists prefer this kind of vertical access if
it can be found," Haxton said.
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- Access to Homestake would be via elevators from the surface
down to the 7,400-foot level.
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- Wherever it's located, the underground lab will feature
a neutrino detector. Despite some scientists' insistence that 100 trillion
neutrinos, which may be key to understanding the inner workings of the
universe, are whipping merrily through your body each and every second,
you can't detect them just by staring really hard into space.
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- Instead researchers have to set up neutrino traps and
infer their presence from the changes caused when neutrinos collide with
atoms. In the proposed Homestake mine model, the neutrino trap would consist
of 10 tanks, each containing 100,000 tons of super-pure water, with equipment
to detect the sparks of colliding subatomic particles. Each tank would
be at least 20 stories high and more than half the width of a football
field.
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- Neutrino detectors are just one of the many complex features
of the underground lab. Scientists whose site-and-structure proposals make
it past the NSF's initial screening process will get funding to develop
conceptual designs for specific sites, which will then be reviewed again.
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- The NSF has tentatively said construction will begin
in 2008, if one of the half-dozen proposals is found worthy by the NSF
and the National Science Board, and the projected $126 million minimum
cost of building and operating the lab is approved by Congress.
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