India joins hunt for dark matter

NEW DELHI—Ever since a pioneering underground laboratory in India closed 25 years ago, physicists here have lacked a subterranean lair, shielded from cosmic rays, where they could hunt for elusive particles from the cosmos. Now, their long wait is over: On 2 September, India will inaugurate Jaduguda Underground Science Laboratory 550 meters below the surface in an operating uranium mine.

The Jaduguda lab’s primary aim will be to join the hunt for dark matter, the mysterious stuff whose gravity holds galaxies together. “It is a good time for India to apply her best and brightest to this universal mystery,” says Nigel Lockyer, Director of Fermi National Accelerator Laboratory in Batavia, Illinois. Elsewhere the dark matter quest has driven physicists to build ever-deeper labs—Sudbury Neutrino Observatory in Canada, 2.1 kilometers below the surface, is now the deepest—with ever-more-elaborate measures to shield detectors from other particles.

Indian physicists had hoped to compete with the ambitious foreign labs. For 15 years, they have strived to break ground on the India-based Neutrino Observatory, a $230 million lab that would be hewn under a mountain in southern India. That project is in limbo, having failed twice to win environmental approval; backers are now searching for a new site. They see Jaduguda as a lifeline “to keep young experimental scientists engaged in cutting-edge research,” says Sekhar Basu, a nuclear engineer and chairman of the Atomic Energy Commission in Mumbai, India.

With a $32,000 investment, the Saha Institute of Nuclear Physics in Kolkata refurbished a 37-square-meter cavern used for storage at the Jaduguda uranium mining complex, 260 kilometers west of Kolkata. Background radiation from uranium should be minimal, as ore rich in the metal is located at least 300 meters away from the cavern; a more prolific background source may be radon gas seeping through the rock. Work is about to get underway to thoroughly characterize the background and log cosmic particles.

After preliminary measurements are completed, the physicists plan to install a low-temperature cesium iodide detector to search for dark matter. The odds of scooping deeper labs like Sudbury are small. But the new lab’s significance to Indian physics is huge, says Saha neutrino physicist Naba Mondal: “Jaduguda came as a savior.”