The bottom of Europe's deepest mine, 1,100 metres beneath the North Yorkshire coast, is apparently a place for Wimps. Cosmologists believe these "weakly interacting massive particles" make up most matter in the universe but no one on Earth has yet detected one.

The Boulby Underground Laboratory has just been refurbished with a £3.1m government grant. The lab is buried deep in a working salt and potash mine so as to screen its equipment as well as possible from extraneous cosmic rays from space.

The problem is that although scientists believe that billions of Wimps pass through us every second, they hardly interact with ordinary matter and so are extremely difficult to detect. But they should occasionally knock into ordinary atoms - and the Boulby experiments are designed to detect these rare collisions.

Neil Spooner of Sheffield University, one of the researchers involved, compares detecting Wimps to playing billiards with an invisible cue ball: "You don't see the ball itself, but you see the recoil as it hits."

All visible matter in the universe makes up less than 10 per cent of its mass. Astronomers say the remaining 90 per cent must be invisible "dark matter" holding the universe together.

According to the most popular cosmological theories, the dark matter should be sub-atomic particles left over from the Big Bang that gave birth to the universe.

The £3.1m refurbishment has carved out a huge new salt cavern for the lab. Its sensitive detectors are isolated from mining operations with sophisticated barriers.

"If Wimps exist we should find them within three to five years," said Sean Paling of Sheffield University. If no Wimps appear, astronomers and cosmologists will have to rethink their theories of the universe.