Dark Matter team cautious about results

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A team of scientists engaged in the Cryogenic Dark Matter Search (CDMS) experiment have produced a set of results that could indicate the discovery of dark matter.

The experiment, conducted in an old mine half a mile underground in Minnesota, employs 30 detectors made of germanium and silicon designed to detect Weakly Interactive Massive Particles (WIMPs).

The detectors are cooled to close to absolute zero and particle interactines deposit energy as heat and as charges that move in an applied electric field. Data is collected in a computer system and this data is analyzed to determine whether the particle hitting the crystal is a WIMP, particles from radioactive decay, or from space.

So far the experiment, which started at the Soudan mine in 2003, has given no evidence for WIMPs but the scientists are confident that the background noise is now suppressed so well that even one WIMP a year could be detected.

A fresh data set garnered between 2007-2008 indicate two events of characteristics expected from WIMPs, but the scientists say there's still a possibility that the events are background noise.

"We estimate that there is about a one in four chance to have seen two background events, so we can make no claim to have discovered WIMPs."

The scientists will refine the experiment to include three times more detectors by next summer. "We...[are] patiently waiting for WIMPs to come along and provide the perfect billiard ball shots that will offer compelling evidence for the direct detection of dark matter in the laboratory."