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Physics Today

Sept 04

Henderson Mine a Promising Candidate for Underground Lab

Several sites are being considered for a National Underground Science and Engineering Laboratory (NUSEL), according to a news story in the February 2004 issue of Physics Today (page 32). Those locations, including the Homestake and Soudan mines and the Icicle Creek site, each have specific attributes that make them possible choices. The article quotes Kenneth Lande of the University of Pennsylvania as saying that "Homestake has a clear advantage [over other sites] financially, and in terms of timetable." Yet water pouring into Homestake will require extensive and expensive rehabilitation measures just to regain the status quo in a mine that is more than 100 years old. Missing from the site list, however, is one in Colorado that may prove to have the greatest potential of all the proposed locations.

Late in 2002, personnel from the Henderson molybdenum mine, located in central Colorado and owned by Phelps Dodge Corp, came to the Clear Creek County Planning Commission to ask if there was any interest in preserving certain of the mine's facilities for use after the forecasted date for mine closure. Much of the infrastructure, including office buildings, maintenance and machine shops, utilities, water supplies, and sewage treatment facilities were considered highly valuable for redevelopment.

The Henderson mine is located on a 30 000-acre private land parcel in the Arapaho National Forest; the land spans the Continental Divide 40 miles west of Denver, is accessible by Interstate 70 and US Highway 40, and is slightly over one hour from Denver International Airport. The mine consists of more than 150 miles of roughly 15-foot-diameter drifts. The main shaft is 28 feet in diameter with a vertical elevator capable of carrying up to a 50-ton load to the lowest level of the mine.

Mining operations at the Henderson are projected to cease around the year 2020. However, large areas are currently available underground some distance from the mining area, and many uses could coexist with current mine production. Crushed rock and ore are brought to the surface from the mining area by a nearly horizontal conveyor, through a 10-mile-long straight tunnel under the Continental Divide. Two 30-mW substations are fed from two independent 115-kv transmission lines and provide 100% redundant electrical power to the complex. Fiber-optic communications link the entire facility, above and below ground.

In October 2003, the Arapaho Project Inc, a private nonprofit corporation, fostered the formation of the Colorado Alliance for Underground Science and Engineering to further evaluate the Henderson mine's potential for high-energy physics. CAUSE members include the Arapaho Project, the Colorado School of Mines, the University of Colorado at Boulder, Colorado State University, and the Henderson mine. CAUSE is currently working in the physics community to increase awareness of Henderson and its potential for economical, high-energy physics research.

We believe that the scientific community, and particularly the particle and high-energy physics group participants, would benefit immensely from a close and unbiased evaluation of the Henderson site's potential as a national underground laboratory.

In December of 2003, CAUSE members visited with NSF officials regarding NUSEL and other high-energy physics projects. In April 2004, CAUSE founded the Henderson Underground Science and Engineering Project. HUSEP is in contact with NSF regarding the release of new NUSEL solicitations and will submit a proposal for.

Stephen C. Schultz
(scsfallriver@earthlink.net)
Jack B. Stauffer
Arapaho Project Inc
Golden, Colorado

By Michelle Delio

4/04

WIRED

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.

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.

But there are no active deep laboratories in the United States, so American scientists have to use facilities in Canada, Japan, Russia and Italy.

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.

"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."

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.

"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."

The only big problem now -- besides getting Congress to approve the many millions the underground lab will cost -- is where to put it.

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.

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.

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.

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.

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.

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.

"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.

Access to Homestake would be via elevators from the surface down to the 7,400-foot level.

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.

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.

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.

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.