THE SEARCH FOR DARK MATTER

A highly sensitive particle detector, located one mile underground in a cavern at the bottom of a former gold mine in the Black Hills of South Dakota, is an experiment searching for particles of dark matter.

http://www.bbc.co.uk/news/science-environment-26819792

The detector, called LUX, is inside a steel tank containing 70,000 gallons of pure water, free of any naturally occurring radioactivity that could interfere with the experiment. The detector contains 815 lb of liquid xenon. A dark matter particle interacting with the xenon would cause a tiny flash of light.

LUX failed to detect any of the dark matter particles, called weakly interacting massive particles (WIMPs) during a test run last year, but is now being re-run for a longer period of time.

Professor Rick Gaitskell of Brown University, one of the principal scientists leading the LUX search for dark matter, says 'The hypothesis we are working with at the moment is that a WIMP was the relic left-over from the Big Bang, and in fact dominates over the regular material you and I are made of'.

Dark matter may comprise about 85% of all the matter in the universe.

Other experiments are also searching for evidence of dark matter, including the Large Hadron Collider and space telescopes.