San Diego

A gold mine in the Black Hills of South Dakota has been selected as the most likely US site for a proposed national underground physics laboratory.

Deep thoughts: the proposed US facility might rival Japan's Super-Kamiokande (above). Credit: ICRR/UNIV. TOKYO

The laboratory, which would cost between $70 million and $150 million to build, would be used for highly sensitive experiments in neutrino physics and for other physics experiments that must be conducted away from cosmic rays. Currently, US physicists must travel to the Super-Kamiokande facility at Tsukuba Science City, Japan, or Italy's Gran Sasso Laboratories near Rome to participate in such experiments.

As part of an exploratory effort supported jointly by the National Science Foundation and the Department of Energy, a committee of experts looked at five proposed sites before recommending the Homestake Mine — where the University of Pennsylvania has already conducted some experiments — as the most promising.

Scheduled to close as a working mine this autumn, the 125-year-old Homestake is economically attractive, as the necessary access tunnels are already in place. But it also presents certain logistical challenges, because of limitations on the size of equipment that can be transported down its 2,500-metre-deep shafts.

The South Dakota School of Mines and Technology at Rapid City was involved in proposing the Homestake site, both to boost science in the region and as a national resource. But any laboratory that evolves will encompass a broad range of researchers and institutions.

Proponents of the new facility would like to expedite planning so that deep-mine experts can remain on site when the mine closes. But the National Science Foundation and the Department of Energy may struggle to find money for the proposal. The project has yet to be reviewed by agency officials, and state and federal legislation would be needed for the government to assume liability for the mine from its current owners.

Although the panel favoured the South Dakota site, it also recommended environmental assessments of several alternatives in California and Nevada.