Scientists hoping to detect darkmatter deep in a former South Dakota gold mine have taken the last major stepbefore flipping the switch on their delicate experiment and say they may beready to begin collecting data as early as February.
What's regarded as the world's most sensitive dark matterdetector was lowered earlier this month into a 70,000-gallon (264,971 liter)water tank nearly a mile (1.6 kilometers) beneath the earth's surface,shrouding it in enough insulation to hopefully isolate dark matter from thecosmic radiation that makes it impossible to detect above ground.
And if all goes as planned, the data that begins flowingcould answer age-old questions about the universe and its origins, scientistssaid Monday.
"We might well uncover something fantastic," saidHarry Nelson, a professor of physics at University of California, Santa Barbaraand a principal investigator on the Large Underground Xenon experiment."One thing about our field is that it's kind of brutal in that we knowit's expensive and we work hard to only do experiments that are reallyimportant."
This one hasn't been cheap, at about $10 million, but likethe discovery of the Higgs boson — dubbed the "God particle" by some— earlier this year in Switzerland, the detection of dark matter would be aseismic occurrence in the scientific community.
Scientists know dark matter exists by its gravitational pullbut, unlike regular matter and antimatter, it's so far been undetectable.Regular matter accounts for about 4 percent of the universe's mass, and darkmatter makes up about 25 percent. The rest is dark energy, which is also amystery.
The search in South Dakota began in 2003 after the HomestakeGold Mine in the Black Hills' Lead, South Dakota, shuttered for good.Scientists called dibs on the site, and in July, after years of fundraising andplanning, the LUX detector moved into the Sanford Underground ResearchFacility, 4,850 feet (1,478 meters) below the earth's surface. It took two daysto ease the phone booth-sized detector down the once-filthy shaft and walkwaysthat originally opened for mining in 1876 during the Black Hills Gold Rush.
There, the device was further insulated from cosmicradiation by being submerged in water that's run through reverse osmosisfilters to deionize and clean it.
"The construction phase is winding down, and now we'restarting the commissioning phase, meaning we start to operate the systemsunderground," said Jeremy Mock, a graduate student at the University ofCalifornia, Davis who has worked on the LUX experiment for five years.
Carefully submerging the delicate detector into its finalhome — a water-filled vat that's 20 feet (6 meters) tall and 25 feet (7.6meters) in diameter — took more than two months, Mock said.
Scientists are currently working to finish the plumbingneeded to keep the xenon as clean as possible. The xenon, in both liquid andgas form, will fill the detector and be continuously circulated through apurifier that works much like a dialysis machine, pulling the substance out toremove impurities before pushing it back into the detector.
Keeping the water and xenon pristine will help remove whatNelson called "fake sources" — or stuff that scientists have seenbefore, such as radiation, that could serve as false alarms in their efforts todetect dark matter.
Nelson likens the experiment to Sherlock Holmes' approach todiscovering the unknown by eliminating the known.
Once the data start to flow, it'll take a month or twobefore the detector is sensitive enough to claim the "most-sensitive"title, Nelson said.
After that, the scientists involved hope to start seeingwhat they covet most: something they've never seen before.